Giannobile, et al. Bone as a Tissue (CH 4). Clinical Periodontology and Implant Dentistry, Lindhe, J.; Lang, K. 5th Edition, 2008, Blackwell Munksgaard (Volume 1).
Lindhe, Berglundh, Lang. Osseointegration (CH 5). Clinical Periodontology and Implant Dentistry, Lindhe, J.; Lang, K. 5th Edition, 2008, Blackwell Munksgaard (Volume 1).
Boioli L et al: A meta-analytic, quatitative assessment of osseointegration establishment and evolotuin of submerged and non-submerged endosseous titanium oral implants. Clin Oral Implants Res. 12: 579-88, 2001 (Duplicate from Implant I)
Albrektsson T et al: The long term efficacy of currently used dental implants: A review and proposed criteria of success. Int J Oral Max Implants 1:11-26, 1986 (Duplicate from implant I)
Albrektsson, T et al: Biological aspects of implant dentistry: Osseointegration. Periodontology 2000 4:58-73, 1994
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
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
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
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.
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.
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]
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
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
Topic: Platform-Switched laser-microchannel implants assessment of osseointegration
Authors: Boioli L et al
Title: A meta-analytic, quantitative assessment of osseointegration establishment and evolution of submerged and non-submerged endosseous titanium oral implants
Source: Clin Oral Implants Res. 12: 579-88, 2001
Type:
Meta-analysis
Rating: Good
Keywords: dental implants, submerged, non-submerged, life table analysis, survival rates, review
Background: Two implant placement methods are used in oral implantology: submerged (S, two-stage surgical procedure) and non-submerged (NS, one-stage surgery). However, a quantitative assessment of their influence on implant osseointegration, summarising the whole present experience, is not directly possible, owing to the lack of normalisation of the published results
Purpose: to help improve the quantitative assessment of this
influence by defining normalisation criteria, which would allow the pooling of
the results of the studies meeting them and, hence, the statistical treatment of
the overall longitudinal results.
Methods:
A survey of the literature was performed on studies report on implants placed either with a submerged (S) or a non-sub- merged (NS) procedure. Only root-analogue, threaded implants, exclusively made of titanium, were considered.
Among the studies meeting all criteria, 65 concerned S implants and 18 NS implants. One study concerned both S and NS implants.
Survival life tables are established (up to 15 and 10 years respectively for S and NS implants placed in normal situations) for extended samples (13049 S and 5515 NS implants).
Early (before loading) failure rates and 95% confidence level ranges of cumulative implant survival rates (CSR) have been evaluated.
Results:
Both categories match current survival requirements, but with a quite different behavior over time.
NS implants, while osseointegrating better initially, are subject to causes of osseointegration loss, which persist over a longer period of time.
Implant design characteristics (including the type of surface) seem to be more relevant than the placement procedure for the implant's behavior.
Conclusion:
S and NS implants give acceptable results in terms of survival, and for both categories (but especially for S implants) the placement stage remains a discernible individual cause of failure
S implants have been studied more than NS implants, and present less dispersed results; NS implants are particularly affected by a reduced sample after 5–6 years of observation: the findings for this period still require confirmation;
NS implants seem to show a better osseointegration establishment, but, unlike S implants, an osseointegration loss process lasting for a longer period of time; subject to further confirmation, the type of placement procedure seems to be of lesser importance for the behavior of the implants, compared with implant design characteristics, including those related to their surface.
Topic: Implant Success
Authors: Albrektsson T, Zarb, Worthington, Eriksson
Tittle: The long term efficacy of currently used dental implants: A review and proposed criteria of success.
Source: Int J Oral Max Implants
Type: Discussion article
Rating: Fair
Keywords: success, osseointegration
Purpose: This paper is an attempt to evaluate currently used dental
implant systems and to propose criteria of success.
Discussion:
Observations:
Osseointegration: is a histological definition, and only partially a clinical and radiographic one. An implant can only be judged as osseointegrated in the context of a continuum of observation, since undermining interfacial changes may be gradual, and not evident at the radiographic resolution level at least in the short term.
Topic: microscopic evaluation of osseointegration
Authors: Albrektsson T, Johansson C, Sennerby L
Title: Biological aspects of implant dentistry: Osseointegration.
Source: Periodontology 2000 4:58-73, 1994
Type: Discussion/Review
Rating: Good
Keywords: osseointegration
Purpose: To analyze current knowledge on osseointegration.
Discussion:
Radiographic evaluation:
Due to the surrounding bone tissue, an implant may seem to be in direct bone contact even though there is obvious soft tissue coat in reality. The maximal resolution level of radiography, under ideal conditions, is 0.1 mm, which is 10 times the size of a soft tissue cell.
Light microscopic investigations of bone-to-implant interface:
The use of modern cutting and grinding techniques has clearly demonstrated that direct bone-to-implant contact at the light microscopic resolution level is possible with many different metallic and ceramic materials. In loaded clinical cases there are indications that what is referred to as osseointegration depends on material used as one of several factors being important for implant take.
Ultrastructural investigation of experimental implants:
Ultrastructural analysis of the implant-bone interface is technically very difficult, since ultrathin sections are needed for transmission electron microscopy. Most ultrastructural investigations have been performed in animals using metal-coated polycarbonate implants, which permits sectioning, or metal plugs from which the tissue has been separated before sectioning.
Comments on published ultrastructural investigations:
The in vivo interface scenario seems to be completely different from that observed in vitro. In vitro the only cells in direct contact with the implant surface were red blood cells and macrophages, during the early healing phase, and later, multinuclear giant cells. The inner most interface was the last area to be mineralized, and this process seemed to be acellular. The amorphous layer, and in some instance the electron-dense layer, cold be distinguished before extracellular matrix became mineralized.
The commercially pure titanium bone interface in relation to other
interfaces:
The interface descriptions found in the literature point to a variability of the interface morphology both for bone-bonding (hydroxyapatite or bioglass) and non-bone-bonding materials (titanium), which is why this type of classification cold be criticized.
The ultrastructure of the bone-titanium interface:
There is one type of amorphous layer in the bone-to-metal interface, even if the width and the content (mineral, collagen, and proteoglycans) has been debated.
Evaluation of retrieved oral implants removed despite a remaining anchorage:
In general, a nonmineralized amorphous layer 200-400 nm wide was bordering the mineralized bone with an electron-dense lamina limitans-like line (50 nm thick). Areas with nonmineralized tissue containing collagen and sometimes osteocytes or vessels were present along the interface.
Conclusion: The only acceptable mode of defining osseointegration is based on clinical examination finding stable implants: a process in which clinically asymptomatic rigid fixation of alloplastic materials is achieved and maintained in bone during functional loading.
Topic: Anatomy bone adaptaion
Authors: Trisi, P., Rebaudi A
Title: Progressive bone adaptaion of titanium implants during and after orthodontic load in humans.
Source: Int J Periodontics Restorative Dent. 2002 Feb; 22(1):31-43
Type: Histology
Rating: Good
Keywords: orthodontics, implants
Purpose: To evaluate implant stability and peri-implant bone reaction by
histologic and clinical evaluation after therapeutic orthodontic loads.
Methods: 41 adult patients received titanium implants (Exacta) as an orthodontic anchorage device; 12 patients received a retromolar or palatal implant to obtain tooth movement. Seven implants were removed at the end of the orthodontic therapy, after 2, 4, 6, and 12 months of orthodontic load, and processed for histologic examination.
Results: It was possible to distalize maxillary and mandibular molars and a group of teeth (molars and premolars), and to obtain tipping, uprighting, intrusion, extrusion, and transfer of anchorage in other parts of the mouth. The results showed that orthodontic therapy is facilitated and quickened using implants. All implants remained stable in the bone up to 12 months of loading, and all were osseointegrated. Microfractures, microcracks, and microcalli were observed around implants that had been placed in both low- and high-density bone. The remodeling rate was still elevated after 18 months.
Conclusion: Loading implants after 2 months of healing was shown to be safe and is considered the standard for orthodontic implants.
Topic: Osseointegration
Title: Early bone formation adjacent to rough and turned endosseous implant surfaces. An experimental study in the dog
Author: Abrahamsson I, Berglundh, T, et al.
Source: Clinical Oral Implants Research, 15 (2004), pp. 381–392
Type: Histologic study, animal model
Rating: Good
Keywords: SLA, osseointegration, implant surface
Objective: To validate a proposed model (as proposed by Berglundh et al.
2003) and to evaluate the rate and degree of osseointegration at turned (T) and
sand blasted and acid etched (SLA) implant surfaces during early phases of
healing.
Methods: Twenty Labrador dogs received totally 160 experimental devices (solid screw implant with either a SLA or a T surface configuration) as to evaluate healing between 2h and 12 weeks. Histometric and morphometric analyses were performed.
Results: The sections provided an overview of the various phases of tissue formation, while the decalcified, thin sections enabled a more detailed study of events involved in bone tissue modeling and remodeling for both SLA and T surfaces. The initially empty wound chamber became occupied with a coagulum and a granulation tissue that was replaced by a provisional matrix. The process of bone formation started already during the first week. The newly formed bone present at the lateral border of the cut bony bed appeared to be continuous with the parent bone, but on the SLA surface woven bone was also found at a distance from the parent bone. Parallel-fibered and/or lamellar bone as well as bone marrow replaced this primary bone after 4 weeks. In the SLA chambers, more bone-to-device contact, more initial woven bone and earlier lamellar bone formation was found than in the T chambers.
Conclusions: Osseointegration represents a dynamic process both during its establishment and its maintenance. While healing showed similar characteristics with resorptive and appositional events for both SLA and T surfaces, the rate and degree of osseointegration were superior for the SLA compared with the T chambers.
Topic: Osseointegration
Authors: Berglundh T, Abrahamsson I, et al.
Title: Bone healing at implants with a fluoride-modified surface: an experimental study in dogs.
Source: Clinical Oral Implants Research, 18 (2007), pp. 147–152
Type: Animal study
Rating: Good
Keywords: dental implants, histology, osseointegration, titanium
Purpose: Study early stages of osseointegration to implants with
a fluoride-modified surface.
Methods: Six mongrel dogs, about 1-year old, were used. All mandibular premolars and the first mandibular molars were extracted. Three months later, mucoperiosteal flaps were elevated in one side of the mandible and six sites were identified for implant placement. The control implants (MicroThread) had a TiOblast surface, while the test implants (OsseoSpeed) had a fluoride-modified TiOblast surface. Both types of implants had a similar geometry, a diameter of 3.5 mm and were 8 mm long. Following installation, cover screws were placed and the flaps were adjusted and sutured to cover all implants. Four weeks after the first implant surgery, the installation procedure was repeated in the opposite side of the mandible. Two weeks later, biopsies were obtained and prepared for histological analysis. The void that occurred between the cut bone wall of the recipient site and the macro-threads of the implant immediately following implant installation was used to study early bone formation.
Results: The amount of new bone that formed in the voids within the first 2 weeks of healing was larger at fluoride-modified implants (test) than at TiOblast (control) implants. It was further observed that the amount of bone-to-implant contact that had been established after 2 weeks in the macro-threaded portion of the implant was significantly larger at the test implants than at the controls.
Conclusions: It is suggested that the fluoride-modified implant surface promotes osseointegration in the early phase of healing following implant installation.
Topic: biomechanical determinants of implant stability
Authors: Mathieu V, Vayron R, et al.
Title: Biomechanical determinants of the stability of dental implants: Influence of the bone-implant interface properties.
Source: J Biomech. 2014 Jan 3;47(1):3-13. doi: 10.1016/j.jbiomech.2013.09.021.
Type: review
Rating: good
Keywords: Biomechanical properties; Bone; Implant; Osseointegration; Stability
Background: Dental implants are widely used however, risks of failure are still experienced and remain difficult to anticipate. The stability of biomaterials inserted in bone tissue depends on multiscale phenomena of biomechanical (bone-implant interlocking) and of biological (mechanotransduction) natures.
Purpose: to provide an overview of the biomechanical behavior of the bone-dental implant interface as a function of its environment by considering in silico (via computer simulation), ex vivo and in vivo studies including animal models as well as clinical studies.
Discussion:
Description of the bone-implant interface: the interface has a complex nature due to (i) its roughness, (ii) the fact that bone is in partial contact with the implant, (iii) adhesion phenomena between bone and the implant and (iv) the time-evolving nature of the interface properties.
Geometrical description; bone-implant distance and micromotions: When primary stability is not sufficient, micro-movements may appear preventing good healing conditions and leading to the formation of fibrous tissue and to surgical failure. Some studies show that micromotion should not exceed 150 µm, however the precise threshold is not yet known.
Mechanical description: stresses and the interface; When functional loading exerted via the implant exceeds “a certain stress”, the implant is regarded as being “overloaded”, leading to possible complications such as peri-implant bone resorption. However, stresses below that are beneficial for the implant outcome and stimulate bone remodeling phenomena. The determination of the value of that threshold remains unclear.
Dynamic description: bone remodeling and osseointegration; implant osseointegration was discovered by Branemark. Diagram bellow shows the multi-scale and multi-time nature of the different phenomena occurring during osseointegration; Factors related to implant properties (dashed lines), to the surgeon (dotted line) and the ones relating to bone properties (solid lines).
Implant stability: a space-time multiscale issue
Measurement of the multiscale bone properties around the interface:
Histology: the gold standard measurement.
Small angle X-ray scattering (SXAS): is used to assess thickness, orientation, and shape/arrangement of the mineral crystals in bone tissue. Gives information about bone mineralization but no information about mechanical properties
Nanoindentation: investigates biomechanical properties in the microscopic scale. Has shown that Young’s modulus and hardness values are lower in the vicinity of the implant than in mature bone.
Scanning Acoustic Microscopy (SAM): qualitative assessment of the biomechanical microstructural properties of bone-implant interface
Micro Brillouin scattering: uses the photo acoustic interaction between a laser beam and a sample to measure bone speed of sound
Homogenization approaches of bone tissue around the interface: homogenization techniques have been developed to climb the hierarchy of scales in newly formed bone tissue, from the nanoscale up to the macroscopic level.
Multiscale biomechanical modeling of the bone-implant interface: Various approaches have been developed to model the mechanical behavior of the bone–implant interface such as; Finite element methods (FEM), Frictional coulomb law, non-linear anisotropic FEM, …
Implant stability assessment
X-ray and MRI based techniques: Limited resolution of clinical X-ray based techniques due to metal artifacts related to the presence of the implant metallic components. MRI has also been proposed but is also of limited interest due to magnetic fields disturbance. Maximum resolution level of radiography is 0.1mm which is ten times the size of a soft tissue cell. X-ray or MRI based techniques are not commonly used in order to assess the biomechanical properties of bone to implant interface
Invasive biomechanical methods: Tensional test, Push out/Pull out test, Removal torque analysis
Non-invasive biomechanical methods:
Empirical approaches; Hitting the implant with an instrument and listen to the noise made by the system. Insertion torque during the surgical procedure.
Impact based approaches: PerioTest device (Schulte et al. 1980) was originally used for evaluation of tooth mobility. Measurement leads to PerioTest value (PTV), -8 to 50. PTV correlates to mobility and level of marginal bone.
Resonance frequency analysis: Measurement of the first resonance frequency of the bone–implant system. Uses an L-shaped transducer or a “Smartpeg”, which is a piece screwed in the implant abutment. Measurement gives an index called Implant Stability Quotient (ISQ 0-100), system is commercialized under the name Osstell. A correlation was shown between initial ISQ value and; (i) cutting torque, (ii) bone measurements assessed empirically by the surgeon during implant placement, (iii) Cortical bone thickness, (iv) Anatomical region of implantation. Limitations:
Only captures the first resonance frequency, which is of limited value from a structural mechanics point of view (“oversimplification”)
Sensitivity of ISQ value to the implant stability depends on the implant type
Relationship between ISQ values and BIC remains unclear
Fixation and orientation of the transducer (or smartpeg) influence significantly the ISQ values
ISQ values are related to the bone properties at the scale of the organ, but properties at the scale of 50-200μm are critical for osseointegration
Quantitative ultrasounds methods: Used to assess bone mineral status, enamel thickness. Several studies show the potentiality of QUS to investigate bone quality around implants, further work is necessary.
Topic: Bone adaptive capacity
Author: Greenstein G, Cavallaro J, Tarnow D.
Title: Assessing bone’s adaptive capacity around dental implants: a literature review.
Source: J Am Dent Assoc. 2013 Apr;144(4):362-8
Type: Review
Reviewer: Phillip Crum
Rating: Good
Keywords: Bone; dental implants; osseointegration; resorption
Purpose:
To review concepts pertaining to bond adaptation that may account for high
survival rates of prostheses that are subjected to increased stresses.
Discussion:
Bone Mechanotransduction
Mechanotransduction=the mechanism that permits bone to detect stimuli.
It is thought that bone cells sense and respond to their mechanical environment by changing their biological and biochemical actions.
It is strain, not stress, that precipitates alteration of the bone response
3 Possible stimuli for Osteocytes
1-Direct mechanical stimulation
2-Fluid flow induced by shear stress
3-Bone Microdamage
The prevailing concept suggests that under dynamic loading, bone matrix deformation produces an interstitial fluid flow. This flow creates shear stress that stimulates osteocytes. Osteocytes act as mechanosensors and convey signals to adjacent cells (osteoblasts) through the intercellular communication network.
Rules For Bone Adaptation to Mechanical Stimuli
According to Turner, the following 3 rules characterize the response of bone to stress
Bone adaptation is determined by dynamic, rather than static, loading, and it is the alteration of stress, not its consistency, that produces bone modifications
A short episode of mechanical loading is required to begin the adaptive response
Bone cells accommodate to customary mechanical loading, making them less responsive to routine loading signals.
From these, it can be deduced that abnormal stress and strains drive structural change.
Stresses and Strains on Bone
Magnitude of occlusal load, cycle number, direction and frequency all can affect the quantity of stress.
The relationship between stress and strain establishes the modulus of elasticity (stiffness) of a material.
According to Frost, a certain amount of stress is required to maintain bone homeostasis.
Microstrains from 0 to 50atrophy
50 to 1500normal bone modeling
1500 to 3000overload
>3000possible destruction
Bone Microdamage
Fatigue: bone has lost strength and stiffness due to repetitive loads.
Microcracks: a discontinuity in the calcium-rich matrix and reflects fissures and breaks in the hydroxyapatite.
Bone’s Proliferative response to stress around dental implants
If the load is above a certain threshold, bone loss or loss of osseointegration can occur.
If functional load is below a destructive threshold, it can be stimulatory and induce apposition of bone and increased osseous density.
There is much evidence that supports the concept that bone can respond to stress and modify itself to withstand increased mechanical forces.
Remodeling
Jee estimated that about 20 percent of the cortical and cancellous bone surfaces (endosteal and periosteal) are remodeling at any point in time.
The replacement rate of cortical bone is 7.7% per year
The replacement rate of cancellous bone is 17.7% per year
Garetto showed that within 1mm of implants, there was a layer of bone that remodeled rapidly. The turnover rate was three to nine times faster per year within the 1mm of the implants.
Bones such as the mandible that experience loading from varying directions exhibit more platelike trabecular architecture. An advantage of this structure is its ability to manage forces from different directions.
High load areas usually manifest dense platelike architecture, whereas low load areas usually demonstrate low-density rodlike structures.
Conclusion: There are 2 possible explanations for the success of prosthetic constructs. First, is that bone is stronger than expected and can tolerate increased stress. Second is that as long as the stress/strain level does not increased beyond a threshold that causes bone destruction, bone has the ability to remodel and model and increase its osseous density.
Topic: Fracture
Authors: Mangano C, Piattelli A, Mortellaro C, Mangano F, Perroti V, Iezzi G
Title: Evaluation of peri-implant bone response in implants retrieved for fracture after more than 20 years of loading. A case series
Source: J Oral Implantol. 2013 Aug 21
Type: Case series
Rating: Good
Keywords: Bone remodeling, human histology, implant surfaces, retrieved dental implants
Purpose: To present a histological case series of the peri-implant bone responses in implants retrieved for fracture after more than 20 years loading period.
Methods: 5 implants retrieved for bodily fracture in 5 patients were found to be analyzed. The surface of these implants was obtained by sandblasting, followed by acid-etching for 30 minutes. The implants were then washed with hydrogen peroxide and dried with high heat. None of the implants were immediately loaded. In 3 cases, implants supported partial fixed bridges, while in 2 cases there was a mandibular ovendenture supported by 2 implants. Four implants were located in the mandible, and 1 in the maxilla. All implants were retrieved with a 5-mm trephine bur. Histological analysis and histomorphometry of the percentages of bone-implant contact were carried out.
Results: Compact, mature bone in close contact with the implant surface was observed in all specimens, with no gaps or connective tissue at the interface. Primarily newly formed bone was observed in proximity of the implant surface. In the most coronal portion of one implant, connective tissue adhering to the implant surface was detected. Bone-to-implant contact percentage ranged from 37.2-76%.
Conclusion: Implant effectiveness is largely dependent on biological stability and integration between bone and implant. Endosseous implants may function over a wide range of degrees of osseointegration.
Topic:
sandblasted and
acid-etched implant surfaces
Authors:
Barewal R et al.
Title: Resonance frequency
measurement of implant stability in vivo on implants with a sandblasted and
acid-etched surface.
Source: J Oral Maxillofac Implants 2003; 18:641-651
Type: Clinical Study
Rating: Good
Keywords: bone, clinical trials, dental implants, early healing, endosseous dental implantation,
implant stability, resonance frequency analysis
Purpose: to understand pattern of stability changes and early healing around single-stage roughened-surface implants during the first 2 ½ months in different bone types.
Methods: Twenty patients had 1 to 4 implants placed in the posterior maxilla or mandible. Bone type was classified into 1 of 4 groups according to the Lekholm and Zarb index (1985). RFA was used for direct measurement of implant stability on the day of implant placement and consecutively once per week for 6 weeks and at weeks 8 and 10.
Results:
Conclusion: The lowest values for interfacial stiffness between the bone and the implant were found at 3 weeks, particularly in type 4 bone. Healing responses of Types 2 and 3 bone were more similar to Type 1 than to Type 4 bone. The RF values at 6 weeks did not differ from those at 10 weeks in all bone types; this supports the idea of a 6-week healing period for ITI implants in Types 1, 2, and 3 bone. The lack of significant change in stability from 5 to 10 weeks for Types 1, 2, and 3 bone supports further testing of an even shorter healing protocol. With regards to Type 4 bone, the current 12- week healing period could be evaluated and potentially shortened.
Topic: implant stability per bone type
Authors: Alsaadi G, Quirynen M, Michiels K, Jacobs R, Steenberghe D
Title: A biomechanical assessment of the relation between the oral implant stability at insertion and subjective bone quality.
Source: Journal of Clinical Periodontology 2007; 34: 359-366.
Type: Clinical
Reviewer: Cynthia Goldin
Rating: Good
Keywords: biomechanics; bone quality; dental implants; insertion torque; oral implants; osseointegration; periotest; RFA
Purpose: To evaluate the validity of subjective bone quality assessment.
Methods: A total of 298 patients treated with implants. Bone quality assessment performed immediately after implant placement and using the Lekholm & Zarb index. Tactile sensation was assessed for cortical bone and trabecular bone during high speed drilling. A scale from 1 (very thick cortex/dense trabecular bone) – 3 / 4 (thin/ poorly mineralized trabecular bone). The bone quality was assessed during implant insertion by an electronic torque force measurement device, which measures the torque force while tapping or inserting the implant at slow speed. The rigidity of implant-bone continuum was assessed by resonance frequency analysis taken at implant insertion and before abutment insertion, through a peg attached to the fixture, and an ISQ value is presented. This runs from 1-100, the higher the ISQ the more stable the implant. Periotest also measured the rigidity. After connecting a temporary abutment 4 mm in length, this device measures the damping capacity of the implant bone continuum. A rod is placed perpendicular to the abutment at a distance of 2 mm and it is accelerated electromagnetically. When rod hits the implant, it is decelerated. The faster the deceleration, the greater implant stability. Values range from -8 (very stable) to +50 (extremely mobile).
Results: Subjective assessment was related to PTV, ISQ and placement torque in the crestal, the second and the apical third.
ISQ and PTV were also compared with the bone quality assessed according to the
Lekholm & Zarb index. A significant relationship was detected.
- Grade 1: 5.3, 73.3
- Grade 3 or 4: 1.6, 55
ISQ and PTV recorded at implant insertion were also compared with the bone quality assessed according to the surgeon’s tactile sensation. A significant relationship was detected between ISQ, PTV and cortical bone grades and between ISQ and trabecular bone grades
For surgeon’s tactile sensation, a good correlation was noted for the presence of a thick cortex: - 4.6, 70.3 or a thin one: - 0.3, 65.9. For dense trabecular bone, the values were - 2.8, 69.4 while for poor trabecular bone, the values were - 1.7, 66.4
Conclusion:
Subjective assessment of bone quality is related to PTV, ISQ and placement torque measurements at implant insertion.
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