Implants – Treatment Planning II

Advanced Surgery and Implant Literature Review

Evaluation of Bone and Soft Tissue
CBCT. Bone quantity and quality. Implant stability
Bone and Soft tissue interface. Keratinized tissue

Rapid Seach Terms:

References:

Diagnostic Imaging

  1. Al-Ekrish AA. Radiology of Implant Dentistry. Radiol Clin North Am. 2018 Jan;56(1):141-156.
  2. Jacobs R, et al. Cone beam computed tomography in implant dentistry: recommendations for clinical use. BMC Oral Health 2018 May 15;18(1):88
  3. Correa LR et al. Planning of dental implant size with digital panoramic radiographs, CBCT-generated panoramic images, and CBCT cross-sectional images. Clin Oral Implants Res. 2014 Jun;25(6)690-95.
  4. Shelley AM, Ferrero A, Brunton P, Goodwin M, Horner K. The impact of CBCT imaging when placing dental implants in the anterior edentulous mandible: a before-after study. Dentomaxillofac Radiology 2015;44(4)

Bone-implant interface (Placement and Initial Healing)

  1. Marão HF et al. Cortical and Trabecular Bone Healing Patterns and Quantification for Three Different Dental Implant Systems. Int J Oral Maxillofac Implants. 2017 May/June;32(3):585-92.
  2. Mathieu V, Vayron R, et al. Biomechanical determinants of the stability of dental implants: Influence of the bone-implant interface properties. J Biomech. 2014 Jan 3;47(1):3-13. doi: 10.1016/j.jbiomech.2013.09.021. Epub 2013 Oct 10.
  3. Trisi, P., Rebaudi A: Progressive bone adaptaion of titanium implants during and after orthodontic load in humans. Int J Periodontics Restorative Dent. 2002 Feb; 22(1):31-43
  4. Tretto PHW et al. Does the instrument used for the implants site preparation influence the bone-implant interface? A systematic review of clinical and animal studies. Int J Oral Maxillofac Surg. 2018 Apr 24 (epub ahead of print)
  5. Trisi P, Berardini M, Falco A, Podaliri Vulpiani M. Validation of value of actual micromotion as a direct measure of implant micromobility after healing (secondary implant stability). An in vivo histologic and biomechanical study. Clin Oral Implants Res. 2016 Jan 4.
  6. Salvi et al. Temporal sequence of hard and soft tissue healing around titanium dental implants. Periodontol 2000. 2015. June;68(1):135-52
  7. Abrahamsson I, Berglundh, T, et al. Early bone formation adjacent to rough and turned endosseous implant surfaces. An experimental study in the dog Clinical Oral Implants Research, 15 (2004), pp. 381–392
  8. Berglundh T, Abrahamsson I, et al. Bone healing at implants with a fluoride-modified surface: an experimental study in dogs. Clinical Oral Implants Research, 18 (2007), pp. 147–152

Bone-implant interface (Function or Failure)

  1. Greenstein G, Cavallaro J, Tarnow D. Assessing bone’s adaptive capacity around dental implants: a literature review. J Am Dent Assoc. 2013 Apr;144(4):362-8.
  2. Mangano C, Piattelli A, et al. Evaluation of peri-implant bone response in implants retrieved for fracture after more than 20 years of loading. A case series. J Oral Implantol. 2013 Aug 21. [Epub ahead of print]
  3. Huang HL et al. Initial stability and bone strain evaluation of the immediately loaded dental implant: an in vitro model study. Clin Oral Implants Res 2011 Jul;22(7):691-8.
  4. Barewal R et al: Resonance Frequence Measurment on Implant Stability in Vivo on Implants with a Sandblasted and Acid – Etched Surface. Int J Oral Maxillofac Implants 2003; 18:641-651
  5. Alsaadi, G et al: A Biomechanical assessment of the relation between the oral implant stability at insertion and subjective bone quality assessment . J Clin Periodontol 2007; 34:359-366

Soft tissue interface with Implants

Supracrestal Attachment Tissues

  1. Berglundh T, Lindhe J. Dimension of the periimplant mucosa. Biological width revisited. J Clin Periodontol 1996;23(10):971-973
  2. Wang Y, Zhang Y, Miron RJ. Health, Maintenance and Recovery of Soft Tissues around Implants. Clin Implants Dent Relat Res. 2016. June;18)3): 618-34.
  3. Abrahamsson, I et al: The mucosal attachment to titanium implants with different surface characteristics: An experimental study in dogs. J Clin Periodontol 2002; 29:448-55
  4. Judgar et al. Biologic width around one- and two-piece implants retrieved from human jaws. Biomed Res Int. 2014;2014:850120

Soft tissue healing around implants

  1. Sculean A, Gruber R, Bosshardt DD. Soft tissue wound healing around teeth and dental implants. J Clin Periodontol 2014 Apr; 41 Suppl 15:S6-22.
  2. Hammerle CH et al. Biology of soft tissue wound healing and regeneration—consensus report of Group 1 of the 10th European workshop on periodontology. J Clin Peridontol. 2014 Apr;41 Suppl 15:S1-5.

Keratinized &/Or Attached Tissue

  1. Block MS, Gardiner D, et al. Hydroxyapatite-coated cylindrical implants in the posterior mandible: 10-year observations. Int J Oral Maxillofac Implants. 1996 Sep-Oct;11(5):626-33. (classic)
  2. Adibrad M, Shahabuei M, Sahabi M Significance of the width of keratinized mucosa on the health status of the supporting tissue around implants supporting overdentures. J Oral Implantol. 2009;35(5):232-7.
  3. Lin GH, Chan HL, Wang HL. The significance of keratinized mucosa on implant health: a systematic review. J Periodontol 2013 Dec;84(12): 1755-67.
  4. Thoma DS et al. Effects of soft tissue augmentation procedures on peri-implant health or disease: A systematic review and meta-analysis. Clin Oral Implants Res. 2018 Mar;29 Suppl 15:32-49.

Tissue Thickness (Periodontal Biotype)/Crestal bone stablity

  1. Rungcharassaeng K, Kan JY, et al. Immediate implant placement and provisionalization with and without a connective tissue graft: an analysis of facial gingival tissue thickness. Int J Periodontics Restorative Dent. 2012 Dec;32(6):657-63.
  2. Linkevicius T, Puisys A, et al Crestal Bone Stability around Implants with Horizontally Matching Connection after Soft Tissue Thickening: A Prospective Clinical Trial. Clin Implant Dent Relat Res. 2015 Jun;17(3): 497-508.
  3. Akcali A, et al. What is the effect of soft tissue thickness on crestal bone loss around dental implants? A systematic review. Clin Oral Imp Res 2017;28:1046-1053
  4. Linkevicius et al. Influence of Vertical Soft Tissue Thickness on Crestal bone Changes around Implants with Platform Switching: A Comparative Clinical Study. Clin Implant Dent Relat Res. 2015 Dec;17(6):1228-36.
  5. Puisys A et al. The use of acellular dermal matrix membrane for vertical soft tissue augmentation during submerged implant placement: a case series. Clin Oral Implants Res. 2015 Apr;26(4):465-70.

Soft Tissue Stability and Restorative Considerations

  1. Rotundo R. et al. Long term outcomes of soft tissue augmentation around dental implants of soft and hard tissue stability: a systematic review. Clin Oral Implants Res. 2015 Sept;26 suppl 11:123-38.
  2. Delgado-Ruiz RA, Calvo-Guirado JL, et al. Connective Tissue Characteristics around Healing Abutments of Different Geometries: New Methodological Technique under Circularly Polarized Light. Clin Implant Dent Relat Res. 2015 Aug;17(4):667-80.
  3. Lops et al. Soft tissues stability of cad-cam and stock abutments in anterior regions: 2-year prospective multicentric cohort study. Clinic Oral Implants Res. 00, 2014, 1-7.
  4. Monaco C, et al. A fully digital approach to replicate peri-implant soft tissue contours and emergence profile in the esthetic zone. Clin Oral Implants Res. 00, 2015,1-4.

 

 Abstracts:

Diagnostic Imaging and Techniques.

Topic: imaging

Authors: Al-Ekrish, A.A.

Title: Radiology of Implant Dentistry

Source: Radiol Clin North Am. 2018;56(1):141-156

DOI: 10.1016/j.rcl.2017.08.010.

Type: Review

Keywords: Dental implants, Multidetector computed tomography, Algorithms, Image processing, Computer-assisted, Radiation dosage

Purpose: To present an overview of the goal of imaging at each stage of implant therapy and the usefulness of multidetector computed tomography (MDCT) in achieving those goals.

Discussion:

Goals of imaging in implant therapeutics:

  • Treatment planning/Pre-operative: evaluate presence/absence of disease at implant site, morphology of bone, evaluate critical anatomy and structures, quality of the bone, plan for optimal implant placement and size
  • Surgical phase: To verify and assist in optimal positioning and orientation.
  • Follow up/ Post-operative: to assess the implant/bone relationship and help with long term implant prognosis

CBCT implantology imaging protocols:

  • Standard dose protocols: Diagnostic reference levels (DRLs) for CT of the face and sinuses in medical imaging have been established as a volume CT Dose Index (CTDIvol) of 35 mGy.
  • Ultra-low-dose protocols: Although CBCT is considered a lower-dose alternative to MDCT, considerable reductions in radiation dose with MDCT have been shown to impart effective doses comparable to, or lower than, those of CBCT.

Radiographic stents: Radiographic stents can be worn by the patient during CT scanning; they are made of low-radiodensity materials and contain high radiodensity markers that indicate the proposed implant position. The radiopaque markers in the stent should demonstrate the position and tilt of the proposed implants and the vertical distance between the proposed occlusal edge of the teeth and crest of bone.

Viewing and analysis of CT images: The diagnostic quality of CT images is influenced by certain factors, of which the effect on implant site imaging must be considered for appropriate imaging, reformatting, and image interpretation.

  • Contrast resolution: Contrast resolution of an image is its ability to demonstrate subtle differences in radiodensity. Contrast resolution decreases with reduced radiation doses.
  • Spatial resolution: High spatial resolution leads to the production of sharply delineated interfaces between gray shades in a CT image. To produce MDCT images, with adequately small voxel size, the images should be acquired with the thinnest slice thickness, largest matrix size possible, and the smallest display field of view (DFOV), which includes the entire region of interest.
  • Artifacts: An artifact is a systematic discrepancy between the CT numbers in the reconstructed image and the true attenuation coefficients of the object. High-density materials, such as amalgam restorations, dental implants, reconstruction plates and screws, and cast metals of prosthodontic appliances, may cause beam-hardening and/or streak artifacts, which may limit visualization of the anatomy adjacent to such materials

Ridge Measurement Considerations:

  1. Assess amount of available bone including; morphology, position, angulation, anatomy
  2. Placement of virtual implants (preferred over linear measurements)
  3. Recommended safety margins are 1mm for implant planning, but with a surgical guide a 2mm safety margin is recommended
  4. Radiographic measures of bone density are not useful in predicting impant stability

Conclusion: Multidetector computed tomography is useful in treatment planning, but has limited use during implant surgery and follow-up of cases. Implant simulations are preferable to linear measurements of implant sites.

Topic: Cone beam computed tomographry

Author: Jacobs R, et al

Title: Cone beam computed tomography in implant dentistry: recommendations for clinical use

Source: BMC Oral Health 2018 May 15;18(1):88

DOI: 10.1186/s12903-018-0523-5

Type: Review

Keywords: Cone beam computed tomography; dental implants; presurgical planning; guidelines; radiation dose; virtual patient

Purpose: To review the literature regarding the use of CBCT in implants dentistry.

Methods:

  • Electronic search of MEDLINE was performed for various topics regarding the use of CBCT in implant dentistry.

Discussion:

Why to use CBCT in Implant dentistry?

  • Overall advantage of using CBCT in implant dentistry is related to its ability to acquire detailed volumetric image date of the maxillofacial region for diagnostic and presurgical planning purposes.
  • Used for diagnostic indications, yet also for presurgical planning and transfer to implant surgery and rehabilitiation.

What is the radiation dose level of dental CBCT?

  • Extremely low dose of radiation exposure results in poor quality image

Evolving from the ALARA principle toward ALADAIP (As Low as Diagnostically Aceptable being Indication-oriented and Patient-specific)

CBCT radiation dose level should preferably be an equivalent to 2 to maximally 10 panoramic radiographs (20-100uSv)

Much variation between different models

Which parameters influence image quality in CBCT?

  • Small voxel size could be diagnostically useful for cases in which small structures such as root canals and periodontal tissues need to be depicted.
  • A shortcoming of CBCT is the lack of diagnostically distinct soft tissue contrast.
  • Hounsfield units do no apply to CBCT images, yielding it impossible to compare grey values among or within patients over time.
  • The reliability of CBCT-based jaw bone density assessment has been found unreliable overtime with significant variations.
  • CBCT images are generally hampered by varying degrees of artifacts expression

When to use CBCT in implant dentistry: existing guidelines?

  • Most recently European Association for Osseointegration stressed the need for adequate and specialist training in relation to the use of CBCT in dental practice, even if simply referring the patient for CBCT

How to apply CBCT guidelines for the individual patient?

How to optimize scanning during presurgical use of CBCT?

  • CBCT imaging should always be carried out while maintaining the correct balance between cost and radiation dose on one hand and required clinical information on the other hand.
  • Protocols should be patient-specific and indication oriented.
  • Presence of restorations, implants, posts and endodontic obturations may significantly hamper the image quality and thus the segmentation procedure during model making for presurgical planning and transfer
  • For surgical guide fabrication, scanning at 200microns resolution may be sufficient.
  • Scanning templates should not be fabricated from a high-density material and/or not be too thick

How to use dental CBCT beyond radiodiagnositics?

  • The available intraoral 3D scanners may offer excellent accuracy
  • By image fusion with basic CBCT data, a digital cast with an accurate surface would thus enable further treatment using integrated 3D dataset for patient-specific CAD/CAM procedures.
  • New integrated 3D facial scanning has become available for various CBCT units. The latter implies a concomitant 3D laser acquisition of facial soft tissues during CBCT scanning. This may allow for a fully integrated planning with the 3D facial tissue scan registered onto the bony skull image, which may contribute to enhancing planning efficiency and prediction of the treatment outcome.

What are the requirements for creating a virtual patient?

  • Virtual patient is a digital record that is used to plan the ideal implant position with respect to aesthetic, prosthetic and surgical requirements. It integrates information (datasets) obtained from facial scanning technology, digital intra-oral impressions and CBCT imaging in one virtual coordinate system
  • For 3D digital smile design, several facial scans in neutral head position, maximum smile and using cheek retractors need to be obtained and merged together and the labial surfaces of the anterior teeth should be clearly depicted to allow registration with the digital dental model scans. In order to integrate facial scanning with CBCT, the forehead region needs to be clearly visible in both scans
  • In partially edentulous cases, the surgical guide is fitted onto the teeth (tooth-supported). The imaging requirements of CBCT in these cases include high fidelity depiction of the dental arches including both teeth and alveolar process. However, CBCT limited spatial and contrast resolution impede accurate 3D reconstruction of the teeth to allow for the fabrication of a surgical guide. Therefore, CBCT 3D models are integrated with digital teeth models obtained using digital intraoral impressions at a spatial resolution of around 50 μm
  • In complete edentulism, typically a radiographic template containing the ideal prosthetic setup would be CBCT scanned together with the patient and the resulting surgical guide would be either bone or gingiva supported. The scan data should also be able to provide good visibility for the radiopaque fiducial markers in the radiographic template and preferably, the outer contour of the gingiva should also be made visible to facilitate accurate implant planning. Perhaps the most promising development in recent years is the mini-implants supported surgical guide placement in completely edentulous patients. Using this approach, the guide is screw retained on mini-implants thereby eliminating the inaccuracies incurred from bony and gingival support. In addition, the mini-implants can be used to fabricate a radiographic template, which can also be employed for creating a virtual teeth try-in. However, studies on this approach are still lacking.

What are the requirements for 3D model making?

  • Poor image resolution may result in insufficient image quality, which is the main cause of 3D model inaccuracy
  • Medium and small FOV allow to obtain more accurate models compared to those acquired with a large FOV; however, small FOVs show more pronounced artifacts and wider grey level variability compared to larger FOV scans

What should we know about metal artifacts in CBCT?

  • Based on the increased material density as compared to titanium, zirconium dioxide implants might thus generate stronger artifacts as compared to other materials.
  • A recent study conducted by Kuusisto et al. demonstrated that composite materials give less artifacts, finding the cut-off point of artifacts at 20% radio-opaque filling material in composite implants
  • Another approach to reduce metal artifact is to implement specific metal artifact reduction (MAR) algorithms, which allow improving image quality, which can be classified into 3 groups:
    • Interpolation-based methods
    • Iterative reconstructive approaches
    • Adaptive Filtering algorithms
  • Limited evidence that MAR algorithms provide additional benefit at this time.

When to use CBCT post-surgically?

Topic: Diagnostic Imaging

Authors: Correa LR et al

Title: Planning of dental implant size with digital panoramic radiographs, CBCT-generated panoramic images, and CBCT cross-sectional images

Source: Clin Oral Implants Res. 2014 Jun;25(6)690-95

Type: clinical

Keywords: cone beam computed tomography; digital panoramic; implant planning; implant size

Background: Panoramic images provide an overview of the jaws and are usually considered adequate in the initial evaluation of the implant site. However, panoramic images do not display the bucco-lingual aspect of the alveolar bone. Knowledge of anatomic features like the location of the mandibular canal, the maxillary sinuses and the nasal cavity, as well as of the angulation and bone volume of the alveolar crest is a prerequisite for appropriate implant treatment planning. The bucco-lingual aspect of the alveolar bone can only be obtained with conventional cross-sectional tomography, computed tomography (CT), or cone beam computed tomography (CBCT).

The American Academy of Oral and Maxillofacial Radiology (AAOMR) recommends that the evaluation of a potential implant site should include cross-sectional imaging, orthogonal to the site of interest (Tyndall & Brooks 2000)

Purpose: to compare the implant size planned with digital panoramic radiographs, cone beam computed tomography (CBCT) generated panoramic views, or CBCT cross-sectional images in four implant systems.

Methods: 71 patients (103 single implants) in the maxillary premolar and/ or mandibular molar sites were examined with digital panoramic radiology (D-PAN) and CBCT. A metal ball 5mm in diameter was placed in the edentulous area for the D-PAN. CBCT data sets were reformatted to a 10-mm thick CBCT panoramic view (CBCT- PAN) and 1-mm cross-sectional (CBCT-cross). Three observers (one periodontist, one radiologist, and one prosthodontist) placed four reference points in the site of the planned implant site. Differences in width and length of the planned implant were analyzed. Implant size selected in the CBCT-cross images was then compared to the selected in the other 2 modalities (D-PAN and CBCT-pan) for each implant system.

Results: The average measurements of the planned implant among observers was narrower when using CBCT-cross compared to both CBCT-pan and D-pan. On average, the periodontist planned wider implants in D-PAN, radiologist recorded shorter implants than the other two, and the prosthodontist recorded narrower implants than the other two except in CBCT-cross view. For pre-molar sites, width differed significantly between D-PAN and CBCT-pan. The planned implant length was also significantly shorter in CBCT-cross than in D-PAN, but not at pre-molar sites. Very little change in implant step sizes was observed whether CBCT-cross was used compared to D-PAN or CBCT-pan.

Conclusion: Selected implant size differs when planned on panoramic or cross-sectional CT images. In most cases, implant size measured in cross-section images was narrower and shorter than implant size measured in panoramic image or CBCT-based panoramic view. Preoperative selection of implant size is influenced by the type of radiographic method used for treatment planning and the implant system to be used. Implant size should not be determined only on images displaying the mesial-distal plane since in most cases, implant size measured on cross-section images was both narrower and shorter than implant size measured on a panoramic image or CBCT-panoramic view. I found the variations between different specialties as well as the different modalities very intriguing. We know conventional panoral films have significant distortion. Some studies show images may be magnified by up to 20 % and this is why they attempted to control for this with the 5 mm metal ball. Before we had CBCT’s when planning cases in partially edentulous cases you could compare the the dimensions of a natural tooth shown on a PA and on a Pan and that would give you the magnification factor. Therefore I was always in the habit of having PA films for all of my implant sites. Do not forget, properly oriented PA films will give you excellent length and MD width measures to compare with your CBCT proposed dimensions. It is another useful tool that you have.

Topic: Imaging

Author: Shelley AM, Ferrero A, Brunton P, Goodwin M, Horner K.

Title: The impact of CBCT imaging when placing dental implants in the anterior edentulous mandible: a before-after study.

Source: Dentomaxillofac Radiology 2015;44(4)

DOI: 10.1259/dmfr.20140316

Type: Clinical

Purpose: To evaluate the use of CBCT imaging in the placement of implants in the anterior mandible using a before and after study design.

Materials and methods:

  • 4 edentulous mandible specimen were created and a simulation was created in which they were placed in a suitably shaped water bath hat mimics the attenuation of X-rays that occurs in clinical imaging. That a material was developed that reproduced the look, radio-opacity and feel of bone when drilling. A phantom head was used into which the models could be placed to simulate implant surgery. The models were made of barium sulphate, sodium bicarbonate, and water added to polyurethane casting resin. Reference cases from four edentulous patients were used to create 4 different cases for each practitioner.
  • 8 practicing dentists were recruited. Each was pretend with the 4 different cases.
  • For each mandible specimen, a panoramic and a trans-symphyseal radiographs were taken. This was deemed the before portion of the experiment.
  • A CBCT was acquired and this data set along with the 2 previous radiographs was the after portion of the simulation.
  • Participants were asked to assess case difficulty, select implants and then drill osteotomies in preparation for implants in the lower canine region for an overdenture.

Results:

  • Perforations in the before group was 22 and in the after group 6. Although there was no significant difference.
  • Implant selection
    • There was no difference in the selection of implant length or design in the before and after group
    • For width changes when alkalized as a whole there was no difference in the selection of implant width. But when analyzing challenging cases only there was a significant difference with narrower implants being selected more often.
  • Case Difficulty
    • There was no significant difference in case difficulty assignation in the before and after groups as a whole
    • When considering challenging cases only there was a significant increase in the level of difficulty selected.

Conclusion: When placing dental implants in the edentulous anterior mandible, the results suggest that the availability of CBCT has no overall impact on the incidence of perforations of the lingual surface of bone. There is weak evidence that CBCT may be helpful in the more challenging cases for some dentists. Perforation of the lingual cortical plate in the anterior mandible can be a rather benign even, but recall from our last seminar, that it may also result in a significant bleeding event. To reiterate my comment from last time try to develop your palpation techniques. It will help you avoid perforations.

Soft tissue interface with Implants

Supracrestal Attachment Tissues

Topic: Biological width

Author: Berglundh et al.

Title: Dimension of the periimplant mucosa. Biological width revisited

Source: J. Clin Periodontol 1996

DOI: ISSN 0303-6979

Type: Animal study

Keywords: periimplant mucosa; attachment; histometry; biological width

Purpose: To determine the dimension of the mucosal-implant attachment at sites with insufficient width of the ridge mucosa.

Methods and materials:

  • 5 beagle dogs (1 year old)
  • Extractions of all mandibular premolars
  • After 3 months implants were placed (Branemark System)
  • 3 implants on each side.
  • After 3 months (healing period) abutment connections were placed
  • On control side muco-periostal flaps were elevated.
  • On test side the soft tissue was dissected to obtain a thin ridge mucosa
  • After 6 months, the dogs were sacrificed

Results

  • Control side;
    • Periimplant soft tissue was on average 3.65mm
    • Length of the junctional epithelium was 2.1 mm
    • Height of the suprabony connective tissue was 1.8mm
  • Test side;
    • 4 of 5 jaws Periimplant soft tissue was on average 2.4mm
    • 1 jaw was 3.3 mm similar to control side
    • Length of the junctional epithelium was 2.0 mm
    • Height of the suprabony connective tissue was 1.3mm
    • Wound healing consistently included bone resorption and an angular bone defect.

Conclusions- Minimum width of the periimplant mucosa is required, and that bone resorption may take place to allow a proper soft tissue attachment to form.

  • It is suggested that once the implant is exposed to the oral environment and in function, a mucosal attachment of a certain minimum dimension is required to protect osseointegration. Need more soft tissue around implant. At least 1mm. Widely quoted aticle. If you do not have sufficient tissue dimension, bone will remodel.

Topic: Supracrestal Attachment Tissues

Author: Wang Y, Zhang Y, Miron RJ.

Title: Health, Maintenance and Recovery of Soft Tissues around Implants.

Source: Clin Implants Dent Relat Res. 2016. June;18)3): 618-34.

Type: Review

Keywords: osseointegration, peri-implant soft tissue, peri-implantitis, peri-mucositis

Goal: To review the process of soft tissue healing around osseointegrated implants and discuss the maintenance requirements as well as the possible short-comings of peri-implant soft tissue integration.

Methods: Literature search on the process involved in osseointegration, soft tissue healing and currently available treatment modalities was performed and a brief description of each process was provided.

Results: The peri-implant interface has been shown to be less effective than natural teeth in resisting bacterial invasion because gingival fiber alignment and reduced vascular supply make it more vulnerable to subsequent peri-implant disease and future bone loss around implants. Common procedures were summarized which have been shown to be effective in preventing peri-implantitis disease progression as well as clinical techniques utilized to regenerate soft tissues with bone loss in advanced cases of peri-implantitis.

One of the issues often overlooked during implant placement is the fact that implant insertion creates a wound in both hard and soft tissue Immediately after dental implant insertion, the implant-mucosa interface also forms a blood clot that is infiltrated by incoming neutrophils. If bacterial invasion is not present, the initial mucosa begins forming a periimplant seal by the fourth day post implantation. Healing takes 8 weeks to complete the perimucosal seal whereby leucocytes are typically confined to the coronal portion of the implant, and collagen-producing fibroblasts are typically found in the apical portion of the peri-implant interface.

Histologically: the peri-implant mucosa is composed of a well-keratinized oral epithelium, sulcular epithelium, and a thin barrier epithelium facing the abutment equivalent to the junctional epithelium around teeth, termed the peri-implant junctional epithelium. The height of the peri-implant junctional epithelium is approximately 2 mm, and the connective tissue underlying this junctional epithelium is around 1.0 to 1.5 mm. Thus, the mean biological width (including the sulcus depth) may often exceed 3 mm.

Probing around implants: deeper PD and higher percentage of positive BOP has been documented around implants in comparison to natural teeth. In addition, PD is more sensitive and reliant on probing pressure.

Fiber Orientation: collagen fibers are oriented in a parallel manner to the implant surface, making them much weaker and more prone to periodontal breakdown and subsequent bacterial invasion

Microbiota and Inflammatory response around implants: Staphylococcus aureus is common in deep peri-implant pockets closely linked to suppuration and bleeding on probing. Human and animals show that there is very little difference in host response between natural and implant-supported teeth in the initial phase. However, in disease, progression occurs more rapidly with subsequent bone loss in the peri-implant lesions than in natural teeth.

Vascular Supply: lack of an abundant blood supply has been suggested as one of the key reasons for the extensive progression of inflammation and lack of healing in soft tissues surrounding implants

Maintaining the health of peri-implant soft tissue:

  1. PATIENT SELF-MANAGEMENT: includes mechanical methods and chemical approaches. Mechanical includes tooth brushing and interdental cleaning. Chemical approaches include Triclosan toothpaste, Fluoride-containing mouthwashes, Essential Oil mouthwash, and CHX.
  2. PROFESSIONAL MANAGEMENT: including mechanical debridement every 6-12 months, application of phosphoric acid etching gel, and CHX.

Recovering the health of peri-implant soft tissue:

Mechanical Debridement: every 12 weeks using curettes and ultrasonic devices with polyether-etherketone-coated tips until implant inflammatory response resolves. Adjunctive Antibiotics: Minocycline microspheres are used because of their sustained release of antibacterial ingredients up to 12 months.(Wrong). In addition, combination of amoxicillin and metronidazole showed significant inhibition on the growth of adherent Streptococcus sanguinis and Porphyromonas gingivalis

Resolution of peri-implantitis:

Non-surgical: The mechanical decontamination methods for peri-implantitis include mainly curettes, air-abrasive devices, ultrasonic devices, and lasers.

Surgical Approaches: surgical techniques and reconstructive procedure are more effective but limited to moderate to severe peri-implantitis. These approaches include Apically positioned flap and Access flap surgeries.

Conclusion: Due to the difference between peri-implant interface and natural teeth, clinicians and patients should pay more attention in the maintenance and recovery of soft tissues around implants.

Topic: Supracrestal Attachment Tissue

Author: Abrahamsson, I. et al.

Title: The mucosal attachment to titanium implants with different surface characteristics: an experimental study in dogs.

Source: J Clin Periodontol 2002; 29: 448–455.

Purpose: The purpose of this study was to study the composition of the soft tissue barrier that formed to implants prepared with well‐defined smooth or rough surfaces.

Methods:

Five beagle dogs were used. Four implants made of c.p. titanium were placed in the right edentulous mandibular premolar region. After 3 months, two different types of abutments were connected: one experimental (OA) with a dual, thermal acid‐etched surface (‘Osseotite®’), and one regular (RA) abutment with a ‘turned’ surface. At the end of a 6‐month period during which proper plaque control had been maintained, biopsies including the implant and the surrounding soft and hard tissues were obtained, decalcified and processed for light and electron microscopy. A confocal He–Ne laser profilometer was used to study the surface topography of the abutments.

Results: The attachment between the peri‐implant mucosa and titanium abutments with either a turned (RA; ‘smooth’) or acid‐etched (OA; ‘rough’) surface was similar from both a quantitative and a qualitative aspect. The attachment comprised a barrier epithelium and a zone of connective tissue attachment of similar dimension at RA and OA. It was further observed that the ‘inner’ zone of the connective tissue attachment at both types of abutment was composed of about 30–33% fibroblasts and 63–66% collagen.

Discussion: The findings of the present experiment revealed that the attachments between the peri‐implant mucosa and titanium abutments with either a turned (RA; ‘smooth’) or acid‐etched (OA; ‘rough’) surface were similar. Thus, examinations of biopsies harvested after about 6 months of healing disclosed that the lengths of the barrier epithelium and the zone of connective attachment were similar at RA and OA. It was further observed that the ‘inner’ zone (zone A) of the connective tissue attachment at both types of abutment was composed of about 30–33% fibroblasts and 63–66% collagen.

At both types of abutments (OA and RA) the marginal 60% of the attachment was occupied by a thin epithelium while a fibroblast‐rich connective tissue was present in the ‘apical’ 40% of the junction.

The inner zone of the connective tissue attachment at RA and OA sites in the present study contained about 35–40% fibroblasts.

In conclusion, the findings from the present animal experiment have clearly demonstrated that the soft tissue attachment that formed to implants made of c.p. titanium was not influenced by the roughness of the titanium surface.

Topic: Biologic Width around implants

Author: Judgar R, et al

Title: Biological Width around One- and Two-Piece Implants Retrieved from Human Jaws

Source: Biomed Res Int. 2014;2014:850120

DOI: http://dx.doi.org/10.1155/2014/850120

Type: Clinical Study

Keywords: Implants biologic width, Junctional epithelium, connective tissue

Purpose: To evaluate the biological with around one and two piece implants retrieved from human jaws.

Methods: Eight partially edentulous healthy human subjects with a mean age of 56 years were included in the study. Patients presenting mandibular bone height lower than 11mm, smoking habit, pregnancy, nursing or systemic conditions were excluded.

Sixteen screw-shaped implants with sandblasted acid-etched surface, 3.3mm diameter and 8mm length were used, and divided into 2 groups (one and two piece implants). All patients received an implant of each group and retrieved with a trephine bur after a healing period of 4 months. Two slides were obtained from each implant and the measurements were as:

-Sulcus Depth (SD): Distance between mucosal margin and most coronal point of junctional epithelium

-Junctional epithelium (JE): Distance between the most coronal point of JE and most apical point of JE

-Connective Tissue Attachment (CTA): Distance between most apical point of JE and the first bone-to-implant contact

Biologic width (BW) was the sum of SD + JE + CTA. Bone to implant contact was also evaluated.

Results: All 16 implants presented no mobility or clinical signs of infection after healing period. Bone density was almost D2, the retrieved implants showed healthy peri-implant bone and osteocytes were present in their lacunae.

-Sulcular epithelium was 0.33 ± 0.07 and 0.36 ± 0.12 (one and two pieces respectively)

-Junctional Epithelium was 1.03 ± 0.06 and 1.05 ± 0.04 (one and two pieces respectively)

-Connective tissue was 1.24 ± 0.23 and 1.87 ± 0.20 (one and two pieces respectively)

An increase of the biologic widths dimension was observed with mean values of 2.55 ± 0.16 and 3.26 ± 0.15 one and two pieces respectively. This difference was influenced by the CTA. SD and JE presented no statistical significant difference.

Discussion/Conclusion:

Around implants, BW determines the minimum dimensions to ensure adequate JE and CT to obtain an optimal seal and to provide protection from mechanical and external biological agents. An external agent invading the BW would induce a response from the epithelium that migrates beyond this agent trying to isolate it. The resulting bone resorption produces a reestablishment of the BW.

The BW was reported to be dependent on the presence/absence of a microgap and its location in relation to the bone crest.

Therefore, within the limits of this histologic report, it could be suggested that the two-piece implant leads to a thicker biological width.

Soft tissue healing around implants

Topic: Soft tissue healing around implants

Author: Sculean et al.

Title: soft tissue wound healing around teeth and dental implants

Source: Journal of clinical periodontology

DOI: 10.1111/jcpe.12206

Type: Narrative review

Keywords: alveolar mucosa, dental implants, gingiva, non-surgical periodontal therapy, periodontal surgery, soft tissue grafting, wound healing

Purpose: the aim of this review was to provide an overview on the mist important biologic events during healing of soft tissue wounds in the oral cavity as related to teeth and dental implants.

Discussion:

Cell biology of soft tissue healing:

  • Brief summary of the classical stages of wound repair: The hemostatic phase: is initiated by tissue injury including defects after periodontal surgery. The inflammatory phase parallels the hemostatic phase. The phase of new tissue formation is initiated by the formation of the “granulation tissue.”The long term remodeling phase that ends up with scar tissue starts with the resolution phase.

Scar tissue formation, also termed Fibrosis, is the main pathological factor of a variety of pathologies linked with inflammation. In periodontal wound healing, sub-epithelial connective tissue grafts can end up with dense tissue, which is considered to provide long-term stability of the area. Therefore, it is reasonable to suggest that a dense and stable soft tissue can bear clinical advantage.

Compare oral with “classical” skin wound healing: The majority of studies indicate that oral mucosa likely heals faster and with less scar tissue than do skin wounds, that may be due to the presence of saliva with its well-recognized biological activities.

Healing of soft tissue wounds at natural teeth. Role of connective tissue and sulcular environment in determining epithelial differentiation. The available Data indicates that the granulation tissue originating from the periodontal ligament or from connective tissue originally covered by keratinized epithelium has the potential to induce keratinization.

Soft tissue healing following non-surgical periodontal therapy. It’s characterized by epithelial proliferation, which appears to be completed after a period of 7-14 days after treatment.

Soft tissue healing following periodontal surgery procedures.

  • Gingivectomy: Immediately after surgery, a haemorrhage is present. At 2 days, a thick clot covered the entire wound and a slight epithelial migration at the apical margin of the wound was observed. At 4 days, the blood clot still covered the major part of the wound surfaces, but the epithelial proliferation was clearly visible from the oral epithelium and epithelial attachment cells. At 1 week, the wound surface was usually completely epithelized and the sulcus reformed but keratinization and the reformation of rete pegs was only detected at 16 days. Wound maturation was still detectable until 38 days, when no differences between the treated areas and the pristine sites were detected.
  • Flap surgery: the tensile strength of the tooth-soft tissue interface still appears vulnerable to mechanical trauma at 7-day post-surgery. At approximately 14 days post-surgery, a structural integrity of a maturing wound between a denuded root surface and a mucogingival flap, which can sufficiently withstand mechanical trauma, is achieved. These observations, in turn point to the critical role of passive flap adaptation and of suturing to allow undisturbed wound maturation.
  • Healing following denudation techniques: The healing following full thickness and split thickness flaps used in mucogingival surgery to increase the width of attached gingiva has been evaluated. The success or failure to extend the width of keratinized tissue by surgical means is unpredictable and depends on the origin of the granulation tissue. It may thus be suggested that the use of transplants is a more predictable method for increasing the width of keratinized tissue.
  • Healing following soft tissue grafting.Free gingival grafts or free connective tissue grafts have been introduced in periodontal therapy to increase the width of the attached gingiva and to prevent or treat gingival recessions. The histological evaluation revealed that the healing of free gingival grafts can be divided into three phases:
  1. Initial phase (0–3 days) characterized by a thin layer of fibrin separating the periosteum from the graft and degeneration of epithelium and desquamation of the outer layers.
  2. Revascularization phase (4–11 days) characterized by minimal resorption of the alveolar crest, proliferation of fibroblasts into the area between the graft and periosteum. At 5 days all the graft epithelium was degenerated and desquamated. At the same time, a thin layer of new epithelial cells proliferated over the graft from the adjacent tissues. At day 11, a dense fibrous union was observed between the graft and the periosteum. Granulation tissue was gradually replaced by fibroblastic proliferation and at day 11 the graft was completely covered by an epithelial layer, which was continuous with the marginal epithelium. Vascularization was evident, and capillary ingrowth was observed at the base of the graft.
  3. Tissue maturation phase (11– 42 days). At 14 days of healing, the connective fibers within the graft were comparable in staining quality and appearance to the fibers in the control specimens. The thickness of the epithelium had developed more fully at 14 days, but no keratinization was present. Keratinization was only detectable at 28 days. At 14 days, the number of vessels throughout the connective tissue of the graft was decreased but in the same time the connective tissue density increased. The pattern of vascularization did not show major changes after day 14.

One important aspect, which needs to be considered when using connective tissue grafts or free gingival grafts, is the shrinkage, which occurs during healing.

Soft tissue healing around implants

  • During the process of wound healing, the features of the peri-implant mucosa are established.
  • Many biomaterial and surgical factors may have an influence on the outcome of soft tissue quantity.
  • The material used for the abutment had a major impact on the location of the soft connective tissue.
  • Compared to teeth, there were less vascular structures in the supracrestal soft connective tissue near the implant than around teeth.
  • The majority of collagen fibers were oriented parallel or parallel-oblique to the implant surfaces.
  • The surface roughness and different materials did not appear to influence fiber orientation.
  • The attachment of the soft connective tissue to the transmucosal portion of an implant is regarded as being weaker than soft connective tissue attachment to the surface of a tooth root.
  • Wound healing and morphogenesis of the peri-implant mucosa after flap surgery in healed ridges: Soft tissue barrier adjacent to titanium implants developed completely within 8 weeks, the dimensions of the soft tissue seal around implants are stable for at least 12 or 15 months .
  • Wound healing and morphogenesis of the peri-implant mucosa after immediate implant placement into fresh extraction sockets: Was observed a fast apical down-growth of the peri-implant junctional epithelium within the first week of healing and a final biological width of approximately 5 mm with a peri-implant junctional epithelium measuring 3.0 to 3.5 mm at 8 weeks.
  • Flap versus flapless healing of the peri- implant mucosa: The diameter of the soft tissue punch should be slightly smaller than the implant to obtain better peri-implant mucosa adaptation and subsequent healing.
  • Flapless implant insertion resulted in less inflammation and early re-epithelialization.
  • Wound healing after probing around implants healing of the epithelial attachment adjacent to dental implants was complete 5 days after clinical probing.

Conclusion:

  • Wound healing in skin and oral wounds follows a similar pattern.
  • The granulation tissue originating from the periodontal ligament or from connective tissue originally covered by keratinized epithelium has the potential to induce keratinization.
  • Epithelial healing following non-surgical and surgical periodontal therapy appears to be completed after a period of 7–14 days.

Author: Hammerle CH et al.

Title: Biology of soft tissue wound healing and regeneration – Consensus Report of Group 1 of the 10th European Workshop on Periodontology

Source: J Clin Periodontol. 2014 Apr;41 Suppl 15:S1-5.

Aims: To review the current knowledge regarding the biological processes of soft tissue wound healing at teeth, implants and on the edentulous ridge. Furthermore, to review soft tissue wound healing at these sites, when using barrier membranes, growth and differentiation factors and soft tissue substitutes.

The scope of Workshop Group 1, focused on two key areas:

  • soft tissue wound healing around teeth and dental implants
  • soft tissue wound healing at teeth, dental implants and the edentulous ridge with barrier membranes, growth and differentiation factors and soft tissue substitutes.

Summary of review for the first part:

  • Oral mucosal and skin wound healing follows a similar pattern of the four phases haemostasis, inflammation, proliferation and maturation/matrix remodeling.
  • Infection control is important for the transition of the inflammatory to the proliferative phase.
  • The connective tissue determines the characteristics of the overlaying oral epithelium.
  • Epithelial healing around teeth following non-surgical and surgical periodontal therapy is completed after 7–14 days.
  • The formation of the biological width and maturation of the barrier function around transmucosal implants requires 6–8 weeks of healing
  • The peri-implant junctional epithelium may reach a greater final length under certain conditions such as implants placed into fresh extraction sockets versus conventional implant procedures in healed sites.

Summary of review for the second part:

The level of evidence available for this review was mostly limited to well-designed pre-clinical studies and to clinical case series or case reports. Regarding recessions at teeth and soft tissue deficiencies at dental implants, the following therapeutic approaches were evaluated: barrier membranes, growth and differentiation factors and soft tissue substitutes. The coronally advanced flap (CAF) with and with-out a CTG was used as a control.

Barrier membranes: The clinical differences between CAF with/without membranes were small in pre-clinical studies providing histology.

Growth and differentiation factors: The factors reported in the review are;

  • Encompassed Enamel Matrix Derivative (EMD)
  • Platelet-Derived Growth Factor (PDGF)
  • Platelet Rich Plasma (PRP)

Histological data from humans have failed to confirm new attachment formation with EMD. In one histological study in humans PDGF (CAF + PDGF) exhibited new attachment formation in contrast to the control group (CAF + CTG). No human histological data is available for PRP.

Soft tissue substitutes: The following materials have been histologically evaluated:

  • Acellular dermal matrix graft (ADMG)
  • Collagen matrices (CM)
  • Human fibroblast-derived dermal substitute (HF-DDS)
  • Human skin equivalents [bilayered cell therapy (BCT)]

ADMG or CM have shown histological similar results to the standard of care, there are no histological data available for HF-DDS and BCT.

Augmentation of insufficient soft tissue volume: modified xenogenic collagen matrix (mCM) has been evaluated and compared with the CTG. The histological analysis demonstrated similar integration into the surrounding tissues.

  • The peri-implant junctional epithelium may reach a greater final length under certain conditions such as implants placed into fresh extraction sockets versus conventional implant procedures in healed sites.

Keratinized &/Or Attached Tissue

Topic: Dental implant survival in posterior mandible.

Author: Block, MS., et al.

Title: Hydroxyapatite-Coated Cylindrical Implants in the Posterior Mandible: 10-Year Observations

Source: INT J ORAL MAXILLOFAC IMPLANTS 1996;11:626–633

DOI: 10.1016/S0278-2391(98)90616-4

Type: prospective cohort.

Keywords: hydroxyapatite, implant, posterior mandible, survival.

Purpose: To determine the survival rate on posterior mandible of hydroxyapatite- coated cilindrical implants to analized all the factors related with implants success.

Methods:All patients who had HA-coated cylindrical implants placed into the posterior mandible from July 1985, to July 1995. 234 implants were followed for more than 5 years and 70 implants for more than 8 years. The patients and their implants were followed up yearly.

Information recorded included survival of implants, radiographically determined crestal bone levels, type of restoration, and length of implants specific to tooth location (sites of the mandibular first and second premolars and first and second molars). 5 periapical radiograph were taken annually. Four surgeons placed the implants, and 15 restorative dentists provided prosthodontic treatment. The Lifetest program in the SAS statistical software (SAS Institute, Cary, NC) was used to calculate cumulative rates and standard errors for the implants.

Results: Thirty-six restorations were nonrigidly connected to natural teeth with various attachments, 38 restorations were rigidly connected to teeth, and 131 were free-standing prostheses. Twenty-one implants were not restored because of insufficient financial resources (n = 15), malposition (n = 3), paresthesia (n = 1), or bone loss found at the time of surgical exposure (n = 2).

The four sites (first premolar, n = 58; second premolar, n = 127; first molar, n = 176; second molar, n = 82. Cumulative survivals were 0.858 ± 0.056 for the first premolar implants, 0.833 ± 0.041 for the second premolar implants, 0.785 ± 0.041 for the first molar implants, and 0.718 ± 0.064 for the second molar implants.

Fifteen patients each had one implant removed. Ten patients each had two implants removed, one had three removed, and three each had four implants removed. One patient had six implants removed, all of which had been placed into bone grafts.

  • Short implants had the lowest successful rate.
  • No differences were found in survival of the implants in partially or totally edentulous posterior mandible.
  • Implants placed in bone graft to restores tumor ablation had a lower success rate than implant place to restore edentulous area.

Discussion:

The survival rates reported in the present study are different than the survival rates reported by other studies. Consequently, more research should be done in order to have more information about it and determine the level of successful in treatment with implants. This study is one of the first that mentioned the lack of KG as a potential reason for implant failure. 56/234 were remove, or 24%

Topic: Effect of keratinized mucosa on implants

Author: Adibrad, M., Shahabuei, M., & Sahabi, M.

Title: Significance of the width of keratinized mucosa on the health status of the supporting tissue around implants supporting overdentures.

Source: Journal of Oral Implantology, 35(5), 232-237.

DOI: https://doi.org/10.1563/AAID-JOI-D-09-00035.1

Type: Clinical study

Keywords: Dental implants, overdentures, keratinized mucosa, peri-implant.

Purpose: Evaluate the correlation between the keratinized mucosal width and health status of the supporting tissue around implants supporting overdentures

Methods:

  • Inclusion criteria: edentulous patients with maxillary or mandibular implant retained overdenture using a bar or single spherical attachments. Patients participated regularly in a maintenance care program after completion of implant prosthodontic treatment and their records and radiographs confirmed that the implants had been clinically successful for the entire time before the measurements took place.
  • Exclusion criteria: Pregnancy, systemic diseases influencing bone and soft tissue, medical conditions requiring prophylactic antibiotics and patient used a systemic antibiotic within the past 6 weeks before the study.
  • Patients were classified into: current smokers, former smokers and never smoked.
  • Clinical examination was performed by an independent and experienced clinician recording the following data:
  1. Number and anatomic location of the implant.
  2. Plaque index.
  3. Gingival index.
  4. Bleeding on probing.
  5. Probing pocket depth.
  6. Mucosal recession.
  7. Periodontal attachment level
  8. Radiographic bone level
  9. Width of keratinized mucosa.

Results: The study included 27 edentulous patients with average age of 63 and 66 restored dental implants. Twenty-four implants were in the maxilla and 42 were in the mandible. Twenty-two patients reported never smoking, 2 were former smokers and 3 were current smokers. Implant length ranged from 8 to 14 mm, and diameters ranged from 3.3 to 4.1 mm.

Discussion: The study demonstrated a significant influence of the width of keratinized mucosa on peri-implant tissue health. The reduced amount of keratinized mucosa around implants supporting overdenture was associated with higher levels of mucosal recession, plaque accumulation, gingival inflammation and bleeding on probing. Very classic article citing the need for AKG around implants

Topic: Keratinized Mucosa

Author: Lin, G., Chan, H., Wang, H.

Title: The Significance of Keratinized Mucosa on Implant Health: A Systematic Review

Source: J Periodontol December 2013, Volume 84, Number 12

DOI: 10.1902/jop.2013.120688

Type: Systematic Review

Keywords: Dental implantation; dental implants; gingiva; gingival recession; peri-implantitis; review

Purpose: The purpose of this systematic review and meta-analysis is to investigate whether or not a minimal width of KM around dental implants has a beneficial effect on the health of peri-implant tissues.

Methods: An electronic search of five databases (from 1965 to October 2012) and a hand search in implant-related journals from January 2000 to October 2012 for relevant articles were performed.

Human cross-sectional or longitudinal studies with data on the relationship between the KM width around dental implants and the variety of periimplant parameters, with a follow-up period of at least 6 months after implant placement, were included. Two reviewers assessed all the included articles independently to evaluate the risk of bias. Eleven studies, seven cross-sectional and four longitudinal, were included. Of these articles, three studies recorded the primary and secondary outcomes on both buccal and lingual sides. Smokers were included in 6 studies.

Results: Each clinical parameter was included in meta-analyses where was calculated by means of weighted mean difference (WMD) and confidence interval (CI). The results showed statistically significant differences in plaque index and modified plaque index, modified gingival index, mucosal recession and attachment loss, all showing better results on implants with wide KM. No statistically significant difference was revealed regarding to the comparison of bleeding on probing, modified bleeding index, GI, probing depth, and radiographic bone loss. However, most comparisons presented considerable heterogeneity between studies; only AL showed low heterogeneity.

Discussion: Limitations of the present review include limited number of selected studies (n = 11), existence of heterogeneity and publication bias, and only English-written articles searched. In addition the results of clinical parameters were strongly related to the degree of patients’ oral hygiene and supportive cares, but this information was not provided in most studies.

Conclusion: However, what can be concluded from this research is that the presence of at least 1 to 2mm wide KM might be beneficial in decreasing plaque accumulation, tissue inflammation, MR, and AL. Based on the available evidence, a lack of adequate KM around endosseous dental implants is associated with more plaque accumulation, tissue inflammation, mucosal recession and attachment loss. Future interventional studies are needed to confirm the above results.

Topic: soft tissue augmentation

Authors: Thoma, D.S., Naenni, N., Figuero, E., Hammerle, C.H.F., Schwarz, F. Jung, R.E., Sanz-Sanchez, I.

Title: Effects of soft tissue augmentation procedures on peri-implant health or disease: A systematic review and meta-analysis

Source: Clin Oral Implants Res 2018; 29, suppl 15: 32-49

DOI: 10.1111/clr.13114

Type: Review

Keywords: dental implant, complication, soft tissue augmentation, peri-implant mucositis, peri-implantitis

Purpose: To perform a systematic review to evaluate the effect of soft tissue augmentation to either increase width of keratinized tissue or improve thickness at dental implant sites.

Methods: An electronic search was performed on Pubmed for controlled clinical studies from 1966 to 2016.

Inclusion criteria:

  • human trials with a minimum amount of 10 patients
  • controlled clinical study
  • follow- up of at least 3 months
  • reported outcome measures following the surgical intervention for gain of keratinized tissue or gain of mucosal thickness

Two groups of meta- analyses were performed based on the type of intervention

  • First group consisted of increasing the width of keratinized tissue
  • Second group consisted of increasing the mucosal thickness

Results: 10 articles met the inclusion criteria, 4 articles for gain of keratinized tissue and 6 for gain of mucosal thickness.

Keratinized tissue augmentation (3 techniques: FGG, collagen matrix, and APF)

  • Meta- analyses on study endpoint BOP values revealed no statistically significant difference between groups with and without soft tissue grafting.
  • A significant difference in favor of the soft tissue grafting group was noticed when comparing change of GI values over time between treatment with an autogenous graft versus maintenance.
  • Comparing final PD values for group APF (apically positioned flap) versus APF plus autogenous tissue resulted in significantly lower values favoring group APF plus autogenous tissue.
  • Statistically significant differences were noted for final marginal bone levels in favor of APF plus autogenous grafts versus all control treatment.

Mucosal thickness (all used sub-epithelial connective tissue)

  • Meta- analysis did not demonstrate any significant influence of grafting procedures on BOP values compared to control groups, neither for changes over time nor for endpoint values.
  • Meta- analysis did not reveal any significant differences regarding PD between grafted (autogenous graft) and control groups (no grafting).
  • Groups without soft tissue grafting lost significantly more marginal bone over time than groups with grafting (marginal significance).
  • No statistically significant differences for change of Pl (Plaque Index) values between grafted and non-grafted groups.

Conclusion: Soft tissue grafts can be recommended to improve implant health. For gain of keratinized tissue, the use of an apically positioned flap in conjunction with autogenous grafts resulted in a greater improvement of bleeding indices and higher marginal bone levels. For gain of mucosal thickness, the use of autogenous grafts resulted in significantly less marginal bone loss over time.

Tissue Thickness (Periodontal Biotype)/Crestal bone stablity

Topic: Tissue thickness

Author: Rungcharassaeng K, Kan JY, et al

Title: Immediate implant placement and provisionalization with and without a connective tissue graft: an analysis of facial gingival tissue thickness

Source: Int J Periodontics Restorative Dent. 2012 Dec;32(6):657-63.

DOI: N/A

Type: Clinical study

Keywords: Tissue thickness, connective tissue graft, implant placement

Purpose: To investigate the change in facial gingival tissue thickness (FGTT) after immediate implant placement with provisionalization (IIPP) with and without a sub-epithelial connective tissue graft (SCTG).

Methods: Patients were selected who needed a single anterior implant. The procedure included immediate placement and provisionalization with or without a connective tissue graft. Tissue thickness was measured immediately after extraction with a caliper 2 mm from the gingival margin. Implants were placed with GTR (allograft and xenograft). Subsequent measurements of FGTT was performed at the time of delivery of the final restoration.

Results: 24 patients were in the group that did not receive grafting. The most common reason for tooth failure was fracture. The mean change in FGTT was 0.32 mm at 8.6 months. 31 patients received SCTG at the time of implant placement. The most common reason for tooth failure was endodontic failure. The mean change in FGTT was1.43 mm at 10.2 months. The mean FGTT in the SCTG was significantly greater at follow-up than the non-grafted group.

Discussion: A significant increase in FGTT was observed in both groups. However, the mean FGTT in the CT group was significantly greater than that in the non-grafted group. Peri-implant gingival tissue thickness is stable and maintainable 6 months after IIPP. IIPP in conjunction with a connective tissue graft is more likely to result in sufficient peri-implant tissue thickness to conceal underlying restorative materials than when performed without a connective tissue graft.

Topic: soft-tissue thickness

Authors: Linkevicius T, Puisys A, et al

Title: Crestal Bone Stability around Implants with Horizontally Matching Connection after Soft Tissue Thickening: A Prospective Clinical Trial.

Source: Clin Implant Dent Relat Res. 2015 Jun;17(3): 497-508

Type: clinical

Keywords: allogenic membrane, biological width, crestal bone loss, thickening of mucosal tissues, thin mucosal tissues

Purpose: To evaluate how implants with horizontally matching connection and laser-modified surface maintain crestal bone stability after soft tissue thickening with allogenic membrane.

Methods: A 1-yr controlled clinical trial was designed for partially edentulous patients receiving implant therapy. Inclusion criteria: systemically healthy, >18yo, missing lower posterior teeth, minimum bone of 6mm width and 8mm height, no periodontal disease, 2mm KG, no bone augmentation before/during implant placement, >35N implant stability. 103 patients (31M/72F) received 1 dental implant. Gingival thickness was assessed when flaps were raised. Patient were assigned to groups based on gingival thickness:

  1. Thin tissues, 34pts
  2. Thin tissues thickened with allogenic membrane, 35pts
  3. Thick tissues 34 patients

Groups A and C implants were placed 1-stage, whereas group B implants were placed in a 2-stage approach. Group B received AlloDerm (Biohorizons) for soft tissue thickening. Standardized radiographs were taken after implant placement, 2 months after healing, after restoration, and after 1-yr follow-up.

Results:

Soft tissue:

  • In groups A and B, average thickness of tissues prior to treatment was 1.51mm
  • After treatment, group B average thickness increased to 3.83mm
  • Group C thickness averaged 2.98mm

Crestal Bone levels:

  • Group A had the most bone loss mesially and distally of each group (B<C<A).
  • Differences between Group A and B and A and C were significant.
  • Difference between B and C were not found to be significant for crestal bone loss.

Conclusion: The major finding of the study was that soft tissue thickening of thin tissues reduced crestal bone loss from 1.81mm to 0.44mm after 1-year. The implants in group A with thin tissue and no augmentation experienced the most bone loss. Implants placed in naturally thick tissue (Group C) had the least bone loss. This study suggests that soft tissue thickness may be the deciding factor in crestal bone loss around implants and not the connection interface. Platform switching may not be necessary. However, this study was designed to place implants in a slightly supracrestal position to move the micro-gap away from the bone. There is also the variation of 1-stage v. 2-stage implant placement that varies in this study.

Topic: Tissue Thickness

Authors: Akcali A, et al.

Title: What is the effect of soft tissue thickness on crestal bone loss around dental implants? A systematic review.

Source: Clin Oral Imp Res 2017;28:1046-1053

DOI: 10.1259/dmfr.20140316

Purpose: To assess whether soft tissue biotype at implant placement has an influence on crestal bone loss (CBL) at 1 year after implant loading.

Methods: Following electronic search in three databases (MEDLINE via OVID, EMBASE and The Cochrane Database) and hand search up to April 2015, two reviewers screened independently and in duplicate the references to identify randomized controlled trials, controlled clinical trials (CCTs) and prospective case series eligible for systematic review and meta-analysis. Cochrane Collaboration’s tool was used for assessing risk of bias.

Initial mucosal tissue biotype were divided into thin < 2mm and thick > 2mm. Patients received implants with late implantation, standard loading protocol and fixed restorations. No restrictions were placed as to flap technique, implant design, or surgical staging.

Results:

  • Studies included a minimum of 19 up to 103 patients
  • In all included trials the operators were specialists and 5 studies reported smokers
  • Patients were divided into thin, thick, and augmented sites.
  • All studies reported a success and survival rate of 100%
  • Regarding changes in vestibular soft tissue dimension, a mean loss in soft tissue height of 0.31 in the thin biotype group and 0.08 in the thick biotype group.
  • The four studies that compared thin vs. thick biotype showed significantly higher crestal bone loss in thin biotype.

Conclusion: At present, there is insufficient amount of evidence to answer the question on the differences in clinical outcome in terms of CBL between implants placed in sites with initial soft tissue thickness <2 mm and those with ≥2 mm.

Topic: Tissue Thickness

Authors: Linkevicius et al

Title: Influence of Vertical Soft Tissue Thickness on Crestal bone Changes around Implants with Platform Switching: A Comparative Clinical Study.

Source: Clin Implant Dent Relat Res. 2015 Dec;17(6):1228-36.

DOI: 10.1111/cid.12222

Type: comparative clinical study

Keywords: clinical study, crestal bone loss, implant design

Background: Platform switching is when an abutment is smaller in diameter than the implant platform. Platform switching can help prevent crestal bone loss, which is vital for the implant’s long-term success and stability. It can also increase the volume of soft tissue around the implant platform.

Materials/Methods:

  • 80 patients
  • Inclusion criteria: >18 years-old, systemically healthy, missing teeth in md molar area, >6mm bone width and 8mm bone height, healthy soft tissue, >4mm KT buccolingually, no bone augmentation before/after implant placement, primary implant stability of 35Ncm.
  • Thin tissue = < 2mm; 40 patients
  • Thick tissue = > 2mm; 40 patients
  • Bone-level 4.1mm implants with platform switched design placed >1.5mm from adjacent teeth, and >1mm buccal/lingual and between implants
  • all implants single screw restorations
  • x-rays taken after placement, 2 months healing, after restorative insertion, 1-year post-reconstruction
  • bone loss categorized by:
  1. No loss
  2. .1-.5mm
  3. .51-1mm
  4. 1.01-1.5mm
  5. >1.5mm

Results:

  • after 1-year function, survival rate 100%
  • thin tissue group had mean thickness of 1.53mm and thick tissue group had mean thickness of 2.98mm
  • after 2 months, thin tissue group had BL of .76mm and thick tissue group had BL of .17mm
  • after restoration, thin tissue group had BL of .97mm and thick tissue group had BL of .21mm
  • after 1-year, thin tissue group had BL of 1.18mm and thick tissue group had BL of .22mm

Conclusion: The best results were achieved for implants in sites with thick mucosal tissue, where only 0.22 mm of bone loss was reported. Initial soft tissue thickness is important for the formation of biological width around implants. vertical soft tissue thickness plays a major part in the etiology of early crestal bone loss. Use of implants with platform switching did not preserve crestal bone if, at the time of implant placement, mucosal tissues were thin. But, in thick tissue, the use of platform switching maintained bone with minimal remodeling. Theory is that platform switching will increase tissue thickness and therefore prevent crestal bone loss.

Topic: Soft Tissue Augmentation

Author: Puisys A. et al.

Title: The use of acellular dermal matrix membrane for vertical soft tissue augmentation during submerged implant placement: a case series.

Source: Clin Oral Implants Res. 2015 Apr;26(4):465-70.

DOI: 10.1111/cIr.12401

Type: Case series

Keywords: allogenic membrane, biologic width, crestal bone loss, thin mucosal tissues, tissue thickening

Purpose: To evaluate the performance of ADM derivative graft in vertical soft tissue augmentation during submerged implant placement, measure the increase of vertical soft tissue thickness after augmentation

Methods:

  • Patients accepted if they had thin (<2mm) mucosal tissues covering an edentulous ridge, missing teeth in lower posterior area, minimum of 6mm bone width and 8mm height with healthy soft tissue, minimum of 4mm KG.
  • Prior to surgery patients were given 1g Amoxicillin and continued taking 0.5g amoxicillin for 1 week
  • Incision was made with 15 at the center of the edentulous ridge leaving 2mm buccal and lingual, full thickness flap raised measuring all soft and hard tissues.
  • Biohorizons implants placed and cover screws placed.
  • ADM was used for vertical augmentation, extended to the neighboring teeth, buccally 10mm and lingually 5mm.
  • Coronal periosteal releasing incisions made, and flaps sutured with primary closure.
  • Patients were given CHX rinse, not to brush for 4 weeks and sutures removed 10 days after surgery.
  • 3 months after healing, new tissue was checked for mobility, second stage surgery where tissue thickness was measured, healing abutment placed, and flaps sutured.

Results:

  • 40 pts total were included in the study, all allografts survived, 39 without any adverse healing.
  • After 3 months all grafts showed complete healing, materials had been covered in healthy tissue.
  • Augmented tissues were immobile, average thickness of 1.54mm prior to surgery and 3.75mm after surgery, which was SSD.
  • 100% survival rate of implants placed.

Discussion: ADM membrane can be used for vertical soft tissue augmentation simultaneously with implant placement. An average gain of 2.34mm can be expected depending on initial thickness.

Soft Tissue Stability and Restorative Considerations

Topic: Soft tissue augmentation

Authors: Rotundo R. et al

Title: Long term outcomes of soft tissue augmentation around dental implants of soft and hard tissue stability: a systematic review

Source: Clin Oral Implants Res. 2015 Sept;26 suppl 11:123-38.

DOI: 10.1111/clr.12629

Type: Systematic Review

Keywords: dental implant, review, soft tissue

Purpose: To examine soft tissue augmentation on soft and hard tissue around dental implants and their long-term stability

Methods: Patients who received dental implants with soft tissue augmentation procedures. The soft tissue augmentation procedures could have been performed: at the same surgical session of dental implant insertion, at the second surgical stage of abutment connection, and after the prosthetic implant-supported rehabilitation. Studies included were randomized control/ control only clinical studies, cohort and case series. Studies were excluded if multiple treated sites in a single patient without appropriate statistical analysis. Out comes that were analyzed were Peri-implant attached/keratinized tissue width changes; Peri-implant marginal soft tissue level changes; Peri-implant soft tissue thickness changes; Peri-implant marginal bone level changes.

Results: two case series studies of only 1 year were used to perform meta-analysis to analyze the peri-implant soft tissue recession reduction after implant coverage procedure. The studies found a mean coverage of 1.65mm. They found 10 articles however none of them were eligible for meta-analysis. There are not enough studies to properly assess in a meta-analysis the soft tissue augmentation overtime.

Conclusion: No long-term evidence whether augmented soft tissues can be maintained overtime and able to influence the peri-implant bone levels.

Topic: Soft Tissue Stability and Restorative Considerations

Author: Delgado-Ruiz RA, et al.

Title: Connective Tissue Characteristics around Healing Abutments of Different Geometries: New Methodological Technique under Circularly Polarized Light.

Source: Clin Implant Dent Relat Res. 2015 Aug;17(4):667-80.

Type: Animal Study

Keywords: connective tissue, dental implants, healing abutments, histology, polarized light

Purpose: To describe contact, thickness, density, and orientation of connective tissue fibers around healing abutments of different geometries by means of a new method using coordinates.

Methods: Bilateral extraction of lower premolars from 6 fox hounds.

  • 36 dental implants were placed after a 2-month healing period.
  • Two different types of abutment were placed.
  • Group A abutments were concave & Group B abutments were wider in diameter
  • Three months after implant placement, implants were extracted with soft tissue and hard tissue.
  • Samples were then analyzed histologically.

Results: No connections between the connective tissue and the healing abutment/implant observed.

  • A space of about 35 μm was observed, instead of a connection
  • The medial zone of Group B abutments exhibited a greater thickness of connective tissue.
  • Basal area showed thicker connective tissue 795 μm (A) and 810 μm (B)
  • Coronal third showed the lowest thickness, no SSD between groups
  • Fibers in Groups A and B showed different orientations.
  • Basal – mainly oblique fibers observed.
  • Medial – more perpendicular fibers, however, large number of fibers with different orientation observed.
  • Coronal – medial zone mainly oblique fibers, external zone mainly perpendicular.
  • Group A exhibited a greater percentage of parallel fibers. Group B exhibited a greater percentage of oblique fibers. Fiber density was higher in the basal and medial areas for both groups.

Discussion: Most research has only considered vertical measurements related to the contact between connective tissue and the abutment/implant surface.

  • The inner border of the ROI was delimited by the abutment/implant surface and the outer by the gingival epithelium, and the border of the basal zone by the crestal bone.
  • The thinnest part of the connective tissue corresponded to the coronal third in both groups.
  • Thickness was less in the medial area of Group A abutments and greater in the medial section of Group B abutments.
  • Convex area in Group A abutment resulted in thinning of connective tissue.
  • Wide Group B abutments resulted in thickening of connective tissue.
  • The greater the thickness of connective tissue, the greater resistance to the mechanical forces arising from mastication.
  • An abutment of a wide profile will favor thicker connective tissue and oblique and perpendicular fiber orientation.
  • Better performance when subjected to the mechanical forces generated by mastication.
  • Prevention of apical migration of junctional epithelium.
  • Data should be treated with caution because of several factors.
  • the small size of the sample, the thickness of the histological sections, the lack of attachment between connective tissue and abutment/implant surface, and the staining procedure.

Conclusion: It may be concluded that an abutment of larger coronal diameter than the implant platform favors oblique and perpendicular collagen fiber orientation and greater connective tissue thickness.

Topic: Soft tissue stability of cad-cam abutments

Author: Lops et al.

Title: Soft tissues stability of cad-cam and stock abutments in anterior regions: 2-year prospective multicentric cohort study

Source: Clin. Oral Impl. Res 2015

DOI: 10.1111/clr.12479

Type: Cohort study

Keywords: anterior regions, cad-cam abutments, soft tissues stability, stock abutments

Purpose: compare the buccal soft tissue stability of Cad-Cam zirconia and titanium abutments to those of stock zirconia and titanium abutments in anterior areas, over a period of 2 years.

Methods and materials:

  • Inclusion criteria;
    • Single edentulism in the anterior maxilla or mandible
    • Absence of local inflammation
    • Absence of oral mucosal disease
    • Adequate oral hygiene
    • Extraction at least 6 months before
    • Adequate bone volume at the implant site
  • Exclusion criteria;
    • Systemic diseases
    • Radiation therapy in the head and neck
    • Current treatment with steroids
    • Neurological or psychiatric handicap
    • Immuno-compromised
    • Clenching or bruxism
    • Smoking habit
    • Drug or alcohol abuse
    • Inadequate compliance.
  • 72 implants in two-stage surgical technique
  • No additional soft or hard tissue grafts were used.
  • During healing phase were placed removable prostheses or provisional fixed bridges
  • 2 different type of abutments were selected for the final restorations:
  • Stock and cad-cam abutments.
  • 4 groups divided by the fixture inclination and the thickness of the facial peri-implant soft tissues.
    • Group 1: 13 zirconia stock abutments.
    • Group 2: 23 titanium stock abutments.
    • Group 3: 20 zirconia cad-cam abutments. (Atlantis)
    • Group 4: 16 titanium cad-cam abutments. (Atlantis)
  • 4 months after implant placement final restorations were placed
  • Metal-ceramic
  • Zirconia-ceramic
  • Follow up with digital photograph of the buccal gingival margin at baseline, 1 and 2 years using 3 lines for measurements.

Results:

  • 100% implant survival rate
  • 1 failure (fracture Zirconia CAD-CAM abutment)
  • 2 abutment unscrewed
  • Mucosal thickness and amount of mucosal recession was not statistically significant.

Conclusion:

  • Best results were showed by cad-cam abutments, both in titanium and zirconia.
  • The buccal mucosal thickness did not seem to influence the mucosal stability after 2 years of follow-up

Topic: Soft Tissue Stability and Restorative Considerations

Author: Monaco C, Evangelisti E, Scotti R, Mignani G, Zucchelli G.

Title A fully digital approach to replicate peri-implant soft tissue contours and emergence profile in the esthetic zone.

Source: Clin Oral Implants Res. 00, 2015,1-4.

Type: Technique article

Keywords: dental implant; digital impression; emergence profile; intraoral scanner; peri-implant tissue; scanbody

Objective: This short communication reports on a novel digital technique designated – the “Fully Digital Technique (FDT)” – to take the impression of the peri-implant soft tissue and emergence profile with an intraoral scanner, digitally capturing both the three dimensional position of the implant platform and the coronal and gingival parts of the provisional retained restoration.

Materials And Methods: A first intraoral digital impression, which generated a standard triangulation language file (STL1), was taken using a standardized implant scanbody to detect the position of the implant. A second digital impression (STL2) with the provisional retained restoration in situ was performed in two steps: the first part of the scan captured all details of the vestibular and palatal sides of the provisional retained restoration and the adjacent teeth. The provisional retained restoration was then unscrewed, and the subgingival part of the restoration was scanned directly out of the mouth to determine its subgingival shape. STL1 and STL2 were imported into imaging software and superimposed using the “best fit” algorithm to achieve a new merged file (STL3) with the 3D implant position, the peri-implant mucosa, and emergence profile. The merged file was used to design the CAD/CAM customized abutment and to realize a stereolithographic model by 3D printing.

Results: The STL superimposition of digital impressions of the implant position and the provisional retained restoration constitute a novel technique to obtain a single STL file with the implant position and its peri-implant mucosal architecture.

Conclusions: FDT is a rapid digital approach for achieving all information of the peri-implant soft tissue and emergence profile directly from the provisional retained restoration.