1. Periodontal Healing Distally to Second Mandibular Molar after Third Molar Coronectomy

2. Development of Implant Stability Quotient values of implants placed with simultaneous sinus floor elevation

3. Clinical performance of two-piece zirconia implants in the posterior mandible and maxilla

4. Treatment of peri-implantitis: clinical outcome of chloramine as an adjunctive to non-surgical therapy

5. Results- Before and After Treatment of Dentin Hypersensitivity with Cyanoacrylate and Laser

6. Zirconia dental implants: where are we now, and where are we heading

7. Clinical Trial Comparing Four Periodontitis Treatment Strategies: 5-Year Tooth Loss Results

8. Correction of Buccal Dehiscence During Immediate Implant Placement Using the Flapless Technique

9. Cortical lamina technique: approach for lateral ridge augmentation using guided bone regeneration

10. Chemotherapeutic decontamination of dental implants colonized by mature multispecies oral biofilm

11. Clinical relevance of dimensional bone and soft tissue alterations post-extraction in esthetic sites

12. Sinus floor elevation procedures to enable implant placement and integration

1

Topic: Periodontal defects of second molars due to third molars

Authors: Vignudelli E, Monaco G, Gatto M, Franco S, Marchetti C, Corinaldesi G

Title: Periodontal Healing Distally to Second Mandibular Molar after Third Molar Coronectomy

Source: J Oral Maxillofac Surg 75:21-27, 2017

Type: Prospective cohort study

Rating: Fair

Keywords: Second molar distal defects

Purpose: To look at the periodontal healing distal to the mandibular second molar after third molar coronectomy.

Methods: 30 patients (9 M, 21 F) with mean age of 28 ± years participated in the study. Clinical parameters were measured at three points distal to the second molar (PD, distance between the marginal crest (MC) and the bottom of the osseous defect (BOD), the distance between the CEJ and the BOD). The significance level was set at P = .05.

Results: At 9 months, a SS reduction in the PD and MC-BOD for all three points distal to the second molar (P = .001). In addition to this, the CEJ-BOD distance showed a SS reduction for all three points distal to the third molar as well. No permanent or temporary neurologic injury occurred to the IAN and no coronectomy failed. The postoperative infection and dry socket rates were similar to those reported in published studies.

Conclusions: After coronectomy of the 3^rd molar, the periodontium distal to the second molar was restored to health. Further studies should be performed to confirm this preliminary clinical result and to compare this method to complete extraction.

2
Topic: ISQ of implants placed with simultaneous sinus lift

Authors: Kuchler U, Chappuis V, Bornstein M, Siewczyk M, Gruber R, Maestre L, Buser D

Title: Development of Implant Stability Quotient values of implants placed with simultaneous sinus floor elevation – results of a prospective study with 109 patients.

Source: Clin. Oral Impl. Res. 28, 2017, 109-115.

Type: Prospective study

Rating: Good

Keywords: autogenous bone grafts, Implant Stability Quotient, dental implant, deproteinized bovine bone mineral, early implant loading, resonance frequency analysis, SLA active, sinus floor elevation

3
Topic: Zirconia implants

Title: Clinical performance of two-piece zirconia implants in the posterior mandible and maxilla: a prospective cohort study over 2 years

Author: Becker J, Gordon J et al

Source: Clinical Oral Implants Research 28, Issue 1 January 2017 Pages 29–35

Type: Prospective Cohort study

Rating: Good

Keywords: cohort, implant survival, zirconia implant

Purpose: To assess the clinical performance of two-piece zirconium implants over a period of up

to 2 years.

Material & methods: A total of 52 patients with single edentulous site in the posterior mandible or

maxilla received the same type of a two-piece zirconium implant system with customized heights

of the restorative transmucosal abutment component. Fibreglass abutments were cemented and restored with fixed all-ceramic single crowns using a conventional loading protocol. At 6, 12 and 24 months and after a gentle supramucosal cleaning, peri-implant sulcus fluid was collected at the deepest aspect of each target implant site by means of sterile paper points. The cumulative survival rate (primary outcome) was calculated. Covariates (gender, implant position, implant diameter/length, surgeon) were evaluated.

Results: No primary stability could be achieved in eight of 60 patients. Accordingly, a total of

52 patients received the final prosthetic reconstructions. A total of two target implants in two patients were lost after a functioning time of 8 months. The cumulative survival rate was 95.8%, and the mean survival time amounted to 32.9 months. Even though both patients were male and both implants revealed a diameter of 5.0 mm, a length of 11 mm and were located in the lower jaw, the log-rank test failed to reveal a significant association between implant survival and gender, implant diameter, implant length or implant position. Similarly, implant survival was also not influenced by the need of an augmentation procedure. However, a significant association was noted for the study variable surgeon. The Kaplan–Meier estimates of mechanical/technical and biological complications amounted to 2.1% and 37.5%, respectively. According to this article’s definition, 18 patients were diagnosed for initial peri-implantitis between 12 and 24 months. The frequency of aMMP-8 levels <8 ng/ml (no inflammation), 8–20 ng/ml (mild inflammation) and >20 ng/ml (severe inflammation) was 37.5% (18 sites), 31.3% (15 sites) and 29.2% (14 sites) at 6 months, respectively. Over the entire observation period, mechanical complications were only observed in 1 patient. At 23 months, a fracture affected the fibreglass abutment of the respective target implant. This was also associated with a technical complication (i.e. fracture) of the cemented crown. The Kaplan–Meier estimates of mechanical and technical complications amounted to 2.1%. The fiberglass fragment could be removed and a new prosthetic restoration cemented, which was successful during the further follow-up. All implant sites revealed a marked increase of the vestibular mucosal level and gain of keratinized tissue at 24 months.

Conclusion: Within the limitations of this study, it was concluded that this two-piece zirconium implant and fiber glass abutment system can be successfully used in the clinical indication investigated.

4
Topic: Peri-Implantitis treatment

Title: Treatment of peri-implantitis: clinical outcome of chloramine as an adjunctive to non-surgical therapy, a randomized clinical trial

Author: Roos-Jansaker AM, Almhojd U et al

Source: Clinical Oral Implants Research 28, Issue 1 January 2017 Pages 43-48

Type: Randomized clinical trial

Rating: Good

Key words: chloramine, non-surgical therapy, peri-implantitis, surface decontamination

Background: A new adjunctive option has recently been launched to the market, Perisolv (RLS Global AB, Gothenburg, Sweden). The active components of Perisolv constitutes of chloramines formed after the chlorine transfer of sodium hypochlorite to the amine functions of the amino acids added. The three amino acids in Perisolv (leucine, lysine and glutamic acid) having three different electrostatic states (acidic, alkaline and hydrophobic) comprise all possible states of the proteins side chains. Upon mixing in alkaline pH, the chlorine of the NaOCl is transferred to each amino acid which lowers the reactivity of the strong parent oxidant and thereby rendered to a less reactive form to healthy tissue. The chloramines formed will oxidize the necrotic tissue which can be found both in the necrotic zone in the mucosal lesion facing the implant surface and the biofilm. During treatment, both mechanical and chemical reactions will act in concert to disrupt the biofilm and remove the granulation tissue. Owing to the selective attack of the solution solely on disrupted proteins, the chemo-mechanical method affects neither sound dentine nor healthy root cement. The high pH will affect calculus and have a softening effect, which will make the cleaning process easier to perform.

Purpose: To evaluate the adjunctive clinical effects of a chloramine to non-surgical treatment of peri-implantitis.

Material and methods: Eighteen individuals diagnosed with peri-implantitis (clinical signs of inflammation and progressive bone loss) on at least two implants were included. Clinical variables; Pl, PD, CAL and BOP, were recorded at baseline and at 3-month follow-up. Primary clinical efficacy variable was the change in the number of sites with BOP. The implants were randomized into two different treatment groups: test and control. Both implants received supra- and submucosal debridement by ultrasonic instrumentation supplemented with hand instruments. The implants assigned to the test group first received local applications of a chloramine gel (Perisolv; RLS Global AB, Gothenburg, Sweden) followed by mechanical instrumentation. The oral hygiene was checked at 6 weeks.

Results: After 3 months, implants of both groups showed statistically significant reduction in the number of BOP-positive sites compared with baseline. The reduction of BOP-positive sites in the test group changed from 0.97 to 0.38 and in the control group from 0.97 to 0.31. Between-group comparisons revealed no statistically significant differences at baseline and after 3 months, for BOP or any of the other variables.

Conclusion: In the present randomized clinical trial of peri-implantitis therapy; non-surgical echanical debridement with adjunctive use of a chloramine is equally effective in the reduction

of mucosal inflammation as conventional non-surgical mechanical debridement up to 3 months.

5
Topic: Dentin Hypersensitivity

Author: Lima TC, Vieira-Barbosa N, de Så Azevedo C, de Matos FR, et al.

Title: Oral Health-Related Quality of Life Before and After Treatment of Dentin Hypersensitivity with Cyanoacrylate and Laser

Source: J Perio, February 2017, Vol. 88, No. 2, 166-172 doi: 10.1902/jop.2016.160216

Type: Longitudinal Study

Rating: Good

Keywords: Controlled clinical trials; cyanoacrylates; dentin desensitizing agents; dentin sensitivity; lasers; quality of life

Background: Dentin hypersensitivity (DH) occurs when dentin is exposed and has a prevalence of 5-85% in adult populations. Recently cyanoacrylate and laser treatment has been used in the treatment of DH. Laser treatment is effective because it increases cellular metabolic activity of Odontoblasts, with consequent production of tertiary dentin and closure of dentinal tubules. Cyanoacrylates are effective by occluding dentinal tubules.

Purpose: The aim of this longitudinal study is to verify changes in the oral health-related quality of life of patients 180 days after treatment of dentin hypersensitivity (DH) with laser and cyanoacrylate.

Methods: This controlled randomized double-masked trial was conducted as a split-mouth design. Teeth of different quadrants received different desensitizers. A total of 62 patients who suffered from DH were assessed. 218 teeth were treated with cyanoacrylate and 216 teeth were treated with laser. Patients wore sleep masks and efforts were taken so patients did not know which quadrants received which treatment. Cyanoacrylates were painted on tooth surfaces using a microbrush three times at 48-hour intervals. The infrared gallium-aluminum-arsenide laser diode (Easy Laser) was used in three sessions, at intervals of 48 hours (795nm wavelength and 120-mW power. Energy density deposited was 30.96 J/cm^2 for 8 secs at 3 points around the cervical region of the tooth. DH was assessed before and after interventions, by evaporative and thermal stimuli. At end of the study, patients were asked if they considered post-treatment DH condition “better,” “the same,” or “worse” than initial DH.

Results: There was a SS difference between treatments only in the time interval of 24 hours after treatment. At this time, cyanoacrylate showed better performance in reducing DH for both stimuli. At all other evaluation time intervals there was NSSD found between the two interventions. In regards to self-evaluation, 50 participants (80.6%) considered their DH was “better,” 10 patients (16.1%) described it as being “the same,” and 2 patients (3.2%) reported it as being “worse.”

Discussion: There is a lack of literature about improvement of oral health-related QOL by means of DH treatment. There was an improvement in the oral health-related QOL of patients with DH treated with cyanoacrylate and lasers. The interventions had similar results at the end of 180 days, but cyanoacrylate proved more effective at 24 hours.

Topic: Zirconia dental implants

Author: Cionca N, Hashim D, Mombelli A

Title: Zirconia dental implants: where are we now, and where are we heading?

Source: Periodontol 2000. 2017 Feb;73(1):241-258. doj: 10.1111/prd.12180

Type: Review

Rating: Good

Keywords: Zirconia dental implants; osseointegration; microbiology

Purpose: To review the development and use of zirconia implants, and to discuss future uses.

Discussion:

Evolution of the Material

• First generation of ceramic implants was made of aluminum oxide.

• Currently, tetragonal zirconia polycrystals, particularly 3 mol% yttrium oxide-stabilized zirconia, is the ceramic of choice for dental implants.

One-piece vs. two-piece implants

• Majority of zirconia implants are one-piece implants. These may not always meet the prosthodontic requirements, and angled abutments to correct misalignment are unavailable. Cementation is the only option for connective prosthodontic elements to one-piece implants. Single-piece implants are immediately exposed to forces from the tongue or as a result of mastication.

• Only a few two-piece implants are available. Prefabricated zirconia abutments were cemented on implants. The challenge with this design is the quality and the strength of the connection between the abutment and the implant.

• Animal study in dogs found a higher fracture rate for one-piece zirconia implants than fro two-piece implants.

• A clinical study showed marked tendency of one-piece implants with a narrow diameter to fracture, epically at the neck.

Osseointegration

• Most studies reported NSSD in bone-to-implant contact and removal torque value between zirconia and titanium implants

• Several animal studies showed improved performance of roughened zirconia implants.

Soft-tissue Integration

• Comparison of the mucosal seal around zirconia and titanium implants with machined necks in 5 adult pics found that collagen fibers in the CT had a similar orientation (parallel and parallel-oblique) on both surfaces

• Smaller proportion of leukocytes was detected in the barrier epithelium around zirconia abutments compared with titanium abutments.

• A SS higher content of collagen and a shorter length of the sulcular epithelium were observed around zirconia implants (0.76mm, compared with 1.4mm at titanium implants). The biological width was 2.3mm for titanium implants and 2.85mm for zirconia implants. Zirconia implants could result in a somewhat more mature soft-tissue integration.

Microbiology

• It has been postulated that bacterial biofilm accumulates less easily on zirconia than on titanium.

• In vitro showed that S. mutans adhered more to zirconia, S. sanguis adhered more to titanium surfaces. No differences were observed for Actinomyces and P. gingivalis.

• Another study examined the emergency of P. gingivalis, T. Forsythia and S. aureus around implants, and at 6 months they found no difference between zirconia and titanium implants.

Inflammatory Reactions

• Inflammatory infiltrate around titanium specimens was more prominent than around zirconia implants

• So far, the limited clinical experience with zirconia implants indicates that peri-implantitis seems to be less of a problem with these types of implants than with titanium implants.

Future Developments

• Different approaches are being studied to improve the physical and chemical properties of the material.

• Need to improve manufacturing protocols to try and eliminate irregularities.

• The addition of 20 weight percent alumina was conceived to limit the effects of aging.

• Two-piece zirconia implants are trending towards becoming screw retained.

Bottom Line: Currently the evidence is still limited an incomplete. Patients are aware of the availability of zirconia implants on the market and we need to be ready to respond to their demands.

7
Topic: Treatment strategies

Authors: Preus HR, Gjermo P, Baelum V

Title: A Randomized Double-Masked Clinical Trial Comparing Four Periodontitis Treatment Strategies: 5-Year Tooth Loss Results

Source: Journal of Periodontology, February 2017, Vol. 88, No. 2 , Pages 144-152

(doi: 10.1902/jop.2016.160332)

Type: Double-masked clinical trial

Rating: Good

Keywords: Anti-bacterial agents, dental scaling, metronidazole, periodontal debridement, tooth extraction, tooth loss

Purpose: To conduct a 5-year randomized clinical trial to determine the effectiveness of 4 treatment modalities for periodontal treatment with tooth loss being the primary endpoint.

Methods: 184 patients (92 males, 92 females, 35-75 years old) with severe chronic periodontal disease were used in this study. After phase I treatment and improvement in oral hygiene to a high standard, patients were selected for the trial if at least 5 sites had residual pockets ≥5 mm. No allergies to medications used were reported in these patients. Participants were then assigned to 1 of 4 groups:

• Full mouth disinfection+ metronidazole (FDIS+MET)

• Full mouth disinfection+ placebo (FDIS)

• Scaling and root planing+ metronidazole (SRP+MET)

• Scaling and root planing+ placebo (SRP)

Clinical follow-up exams were done at 3 months, and 1, 3, and 5 years after treatment. Parameters recorded were plaque, BOP, PD, and CAL. Patients received maintenance at 3, 6, and 12 months after treatment, and every 6 months after that with the periodontist. Regular dentists were seen at 1.5, 2.5, 3.5, and 4.5 years. Extraction necessity and relevant x-rays were all sent to the principle investigator prior to extractions.

Results: 161 patients completed the study. Second molars were most likely missing at baseline. , followed by first molars and maxillary premolars. No significant differences were found among the groups regarding number of teeth retained at 1, 3, and 5 year follow up. Overall, 45% of participants completing the 5 year follow up did not experience tooth loss during the trial. Participants in the SRP+MET group had significantly more teeth extracted in the 5 year period than the FDIS group. Extractions 1 year after treatment were more likely to be related to endodontic problems or fractures/cracks extending into the root and were distributed across the dentition.

Discussion: There was an increased trend for more tooth extractions noted in the SRP+MET group relative to the FDIS or SRP groups. It was found that this group had the fewest teeth present initially, highest number of smokers, and highest average age among groups, which could explain the higher incidence of extractions. A larger sample size would be needed to determine if this was an unwanted side-effect of metronidazole treatment. Overall, none of the 4 treatment modalities showed a significantly greater efficacy at retaining teeth over a 5 year period.

8
Topic: Buccal dihiscence

Authors: Assaf JH, Assaf DC, Antoniazzi RP, Osório LB, França FMG

Title: Correction of Buccal Dehiscence During Immediate Implant Placement Using the Flapless Technique: A Tomographic Evaluation

Source: Journal of Periodontology, February 2017, Vol. 88, No. 2 , Pages 173-180

(doi: 10.1902/jop.2016.160276)

Type: Case series

Rating: Good

Keywords: Bone regeneration, guided tissue regeneration, immediate dental implant loading

Purpose: To evaluate a new technique for treating dehiscence buccal bone sites (Class II) with immediate implant and collagen-enriched bovine derived xenograft blocks without surgical flap or membrane.

Methods: 14 patients requiring immediate implant surgery in the anterior and premolar region were included in this study. Reasons for extraction were root fractures (10) or poor endodontic prognosis (4). Buccal bony defects were present that did not extend to the mesial or distal aspects of the tooth. The defect had to show a minimum depth of 5 mm (established through CT) and extend to the apical third of the root, but not beyond. A thick gingival biotype was required. Implants were placed, with pre-and post-operative antibiotics (2 days) prescribed along with chlorhexidine rinse (2 weeks). The contralateral tooth was used as a standard to compare the defect, and later augmented defect.

Surgical procedure: Intrasulcular incisions were made around the tooth and teeth were extracted atraumatically. Sockets were degranulated and inspected for fenestrations/dehiscences. Periosteum, gingival, and mucosal tissues were detached 3 mm apically to margins around the bony defect with a #1 tunneling instrument through the opening of the socket. Implants were placed palatally, resulting in a gap between the implant shoulder and residual buccal bone wall. This gap was filled with the collagen-enriched bovine-derived xenograft blocks at the level of the intact buccal bone crest adjacent to the defect or at the implant shoulder level. Implants were buried and patients were re-evaluated at 10-15 days and monthly for 6 months thereafter. No flaps or membranes were used in any cases. CT images were taken before surgery and at 6-12 months to evaluate changes in the defect.

Results: No significant differences were noted at 6 and 12 months between contralateral teeth and augmented sites regarding buccal bone wall height, though both were significantly higher than the presurgical defects. Statistically significant differences were observed between treated sites and the contralateral tooth, both in the BL width of the ridge and in buccal wall thickness. Thickness of the buccal wall in the augmented group ranged from 0.9-3.81 while the contralateral tooth showed measurements of 0.25-1.60 mm. BL width ranged from 6.05 to 9.65 mm in the augmented group and 7.43- 10.34 in the contralateral tooth.

Discussion: The greater thickness in the buccal wall of treated teeth is likely due to the size discrepancy between the implant and the extracted tooth (implant diameter was narrower than the tooth). Flapless surgery during immediate implant placement paired with xenograft to repair buccal bone defects led to increased bone in all cases, including around implant shoulders. In certain cases, this could be a valuable approach when placing implants in the anterior area.

9
Topic: allograft cortical shell bone graft

Authors: Deepika-Penmetsa SL, Thomas R, Baron TK, Shah R, Mehta DS.

Title: Cortical lamina technique: A therapeutic approach for lateral ridge augmentation using guided bone regeneration.

Source: J Clin Exp Dent. 2017 Jan 1;9(1):e21-e26. doi: 10.4317/jced.53008. eCollection 2017.

Type: clinical

Rating: good

Keywords: Dental implant, cortical lamina technique, guided bone regeneration, horizontal ridge defect, ridge augmentation.

Purpose: To evaluate the efficacy of a novel technique, the bone lamina technique, in horizontal ridge augmentation, using a combination of allogenic cortical shell, particulate xenograft and resorbable collagen membrane.

Methods: Localized horizontal ridge defects, in ten patients, 6 male, 4 female, age 18-45, generally healthy with bucco-palatal ridge width < 4 mm were included. After prophylaxis, CBCT was taken and stereo-lithographic models were obtained. Augmentin 625 mg and Ketorolac 10 mg was given pre surgery. Mid-crestal incision, FTF beyond MGJ. Localized ridge augmentation was performed using bone lamina technique with mineralized allogenic shell of 1 mm thickness trimmed to the appropriate size using stereo-lithographic models and fixed to the recipient site with stainless steel micro-screws of 1 mm diameter. The space between the shell & host bone was filled with particulate xenograft (Cerabone, Botiss, Germany), followed by placement of collagen membrane and primary closure of the site. Ab continued and Chlx prescribed. Clinical parameters including ridge width before & after flap reflection & radiographic (CBCT) ridge width measurements were recorded pre-operatively, and six months after the augmentation procedure. Results obtained were analyzed statistically.

Results: healing uneventful except one pt where membrane got exposed, was managed by betadine irrigation and ab therapy, healed satisfactory. At 6 month, a mean gain in ridge width of 3.15 ± 0.63 mm (p<0.005) (2 ± 0.7 mm at baseline and 5.15 ± 0.98 mm after 6 month).

Conclusion: It was demonstrated in this study that bone lamina technique can be effective means of horizontal ridge augmentation and the use of mineralized allograft in combination with xenograft and collagen membrane leads to good amount of bone regeneration for subsequent implant placement. Authors believed that this method is comparable with the gold standard of autogenous block grafts.

Critique: long-term follow up?

10
Topic: disinfection of implants

Authors: Dostie S, Alkadi LT, Owen G, Bi J, Shen Y, Haapasalo M, Larjava HS.

Title: Chemotherapeutic decontamination of dental implants colonized by mature multispecies oral biofilm.

Source: J Clin Periodontol. 2017 Jan 24. doi: 10.1111/jcpe.12699. [Epub ahead of print] DOI: 10.1111/jcpe.12699

Type: in vitro

Rating: good

Keywords: Chlorhexidine, phosphoric acid, tetracycline, implant, decontamination, biofilm

Purpose: No studies have tested disinfectants on mature multispecies oral biofilms on titanium substrata. The aim of this study was to investigate the efficacy of commonly used antimicrobial agents in decontamination of multispecies mature oral biofilm on SLA titanium implants.

Methods: SLA titanium disks (5 mm diameter, 1 mm thickness, Straumann) covered with bovine dermal type I collagen. Disks were inoculated with dental plaque from 3 healthy volunteers and cultured anaerobically for 21 days. The disks were rinsed (using a Monojet syringe like the clinical setting) with 5 different solutions used routinely in during surgical treatment of peri-implantitis); 0.9% NaCl, exposed for 2 minutes to tetracycline paste, 1% Chlorhexidine gel (CHX), 35% phosphoric acid gel (Etch) or a novel chemical formula (0.3% cetrimide, 0.1% CHX and 0.5% EDTA) and then rinsed again with 0.9% NaCl. To control the mechanical effect of rinsing, 3 samples per experiment were rinsed with NaCl in the same manner without being subjected to any chemical agent. After 3 weeks, bacteria were quantified from scanning electron micrographs of the implant surfaces. Living/dead bacteria were quantified with confocal laser scanning microscopy (CLSM).

Results & Conclusion: Rinsing the surfaces with 0.9% NaCl removed the majority of the biofilm. However, bacteria persisted in all specimens and none of the disinfectants was superior to the double saline rinse group. Analysis showed that CHX and Etch groups had a statistically significant reduction of viable bacteria, although small. Overall the results show that many disinfection agents used in the clinic are ineffective in biofilm removal and leave live bacteria on the surface.

11
Topic: Extractions

Authors: Chappuis V, Araújo MG, Buser D

Tittle: Clinical relevance of dimensional bone and soft tissue alterations post-extraction in esthetic sites.

Source: Periodontol 2000. 2017 Feb;73(1):73-83. doi: 10.1111/prd.12167.

Type: Discussion article

Rating: Good

Keywords: Extraction, tissue alteration, bone loss

Purpose: to summarize the degree of tissue alterations in single tooth extraction sites of the anterior maxilla and to identify associated modu- lating factors in order to assist the clinician in the selection of the most appropriate treatment protocols to facilitate pleasing esthetic treatment outcomes.

Discussion:

Degree of dimensional tissue alterations following tooth extraction

Bone alterations following tooth extraction

• Experimental studies: Changes are initiated by the resorption of the bundle bone that has a thickness of 0.2–0.4 mm and is a tooth- dependent structure. These changes have been correlated with the disruption of the blood supply from the periodontal ligament, which subsequently leads to significant osteoclastic activity.

• As the bundle bone is gradually resorbed leads to a vertical bone loss of about 2.2 mm in mandibular premolar sites on the facial aspects. In contrast, minimal bone resorption has been observed on the lingual aspect.

• Socket grafting has shown to modify these modeling. Immediate implant insertion into a fresh extraction site failed to prevent the remodeling that occurred in the walls of the socket.

• Post-extraction dimensional alterations appear to be related to several additional factors, including surgical trauma due to flap elevation, lack of functional stimulus on the remaining bone walls and a lack of periodontal ligament and genetic information.

• Clinical studies: In humans, dimensional alterations have been reported to cause a ridge width reduction of up to 50% during the first year following tooth loss in premolar and molar sites, where two-thirds of the total changes take place within the first 3 months post- extraction.

• The dimensional bone and soft tissue alterations following tooth extraction in the anterior maxilla have a significant impact on the esthetic outcome.

• Research has shown that significant bone modeling activities occur during the first 2 weeks of healing.

• Bone modeling in single extraction sites is mainly localized to the central aspect of the facial bone wall, whereas proximal aspects are well maintained by the periodontal ligaments of the adjacent teeth.

• The extent of flapless postextraction bone modeling depends on the facial bone wall thickness. Whereas thin bone wall phenotypes (< 1 mm) often show a progressive bone resorption pattern with extensive vertical loss of the former socket wall, thick bone wall phenotypes (> 1 mm) show only limited resorption rates.

• Regarding dimensional soft tissue alterations, the facial soft tissue thickness does not necessarily correlate with the underlying bone wall dimensions. For thin bone wall phenotypes, extraction leads to spontaneous soft tissue thickening, while no significant changes are seen for thick bone wall phenotypes. Finally, soft tissue thickening in thin bone wall phenotypes may mask the true extent of the underlying defect, which may mislead the clinician during the clinical examination.

• Neither ridge preservation techniques nor immediate implant placement prevents physiological bone modeling activity after tooth extraction. Therefore, tooth extraction should be performed with the understanding that ridge reduction will follow, and further clinical steps should be considered to compensate for such changes when considering replacement of the extracted tooth with an implant-supported restoration.

• Clinical recommendations: Early implant placement, where a healing period of 4– 16 weeks is used prior to implant insertion, and has been recommended as the treatment of choice in sites exhibiting a progressive bone resorption pattern, such as the thin bone wall phenotypes. An immediate implant placement protocol can be recommended in thick bone wall phenotypes and thick gingival biotypes, where the post-extraction bone modeling is expected to be minimal. However, if such ideal conditions are not present, other implant timing protocols are recommended in order to provide predictable esthetic treatment outcomes.

• Soft tissue dimension post-extraction: Overall, more than 50% of these changes occur within 2 weeks of healing.

• Clinical recommendations regarding dimensional soft tissue alterations:

• Socket grafting : The Osteology Consensus Conference in 2012 concluded that the majority of studies and systematic reviews did not reveal significant differences between various biomaterials and treatment approaches.

• Immediate implant placement : It has been suggested that placement of implants into fresh extraction sockets with a bone-to-implant gap of 2 mm or less would prevent remodeling and hence maintain the original shape of the ridge. However, findings reported from a clinical study by Botticelli et al. failed to support this hypothesis. After 4 months of healing the outer surface of the buccal and lingual bone walls was markedly diminished, with a mean reduction of 56% in the buccal aspect and 30% in the lingual aspect. These findings were supported by an experimental study revealing a vertical bone loss of the facial bone wall of, on average 2.6 mm after a 12-week healing period. Recent systematic reviews demonstrated that predictable results are difficult to obtain and that these techniques show an increased risk of significant mucosal recession if this approach is not applied with strict inclusion criteria.

Clinical recommendations

• Preservation of an extraction socket is indicated if immediate or early implant placement is not feasible

• Patient-specific indications for ridge preservation techniques are (i) too young (age < 20 years) and (ii) treatment postponed for medical, financial or social reasons.

• Sites associated with extensive soft tissue defects may require soft tissue grafting in order to improve keratinization prior to implant placement.

• Maintenance of the root until the start of implant treatment is an easy and economical approach, but can only be recommended for roots without an acute or chronic inflammation, decay or a fracture.

• Soft tissue closure of the extraction socket combined with the use of biomaterials with a low substitution rate is advisable, as this seems to retain the tissue volume at the site.

• Immediate implant placement does not prevent bone resorption per se and should only be used in sites where post-extraction bone modeling is expected to be minimal, such as with a thick bone wall phenotype (> 1 mm) and thick gingival biotype, as recommended by the 2013 International Team for Implantology (ITI) consensus conference.

12
Topic: Sinus lift

Authors: Lundgren S, Cricchio G, Hallman M, Jungner M, Rasmusson L, Sennerby L

Tittle: Sinus floor elevation procedures to enable implant placement and integration: techniques, biological aspects and clinical outcomes.

Source: Periodontol 2000. 2017 Feb;73(1):103-120. doi: 10.1111/prd.12165.

Type: Discussion article

Rating: Good

Keywords: sinus lift

Discussion:

Treatment options for sinus floor elevation in the posterior maxilla

• Modern micro-rough surface implants in lengths of about 8-10 mm or longer and of different brands are similarly successful.

• The use of different sinus floor elevation techniques should be considered when < 8 mm of bone is available below the maxillary sinus.

Aspects of implant length and protrusion in the maxillary sinus

• The Academy of Osseointegration Consensus Conference on sinus grafts in 1996: ‘implants placed into a grafted area should not penetrate through the top of the graft, to avoid a nonbone covered tip of the implant in the sinus’.

• However, long-term f/u studies on lateral sinus floor elevation (SL) with autogenous bone grafts, evaluated using CBCT, found that the implant tips often protrude through the grafted area but are covered with a healthy sinus membrane.

• Similar results were found for graftless lateral sinus floor elevation and simultaneous implant placement, in which the apical part was covered with an asymptomatic and normally thick sinus membrane.

• In a retrospective cohort study with a mean follow up of 10 years, 70 patients had 83 implants placed with conventional treatment, which penetrated the sinus floor together with membrane perforation; however, there were no clinical or radiological signs of sinusitis in any of the patients

• To avoid perforation of membrane during the transcrestal SL, the membrane elevation height should not exceed 4 mm. Longer implants may pose a risk for accidental perforation and collapse of the membrane and thereby impair bone formation in the tented space.

• With the graftless lateral sinus floor elevation technique, studies have shown a correlation between bone formation and protruding implant length into the sinus. Therefore, it is recommended to place implants of at least 10 mm in length to ensure an effective tenting effect.

• As a rule of thumb, if transcrestal sinus floor elevation is used the intended elevated height should not exceed the height of the residual bone, while, with lateral sinus floor elevation, the elevated height should exceed the height of the residual bone.

Lateral sinus floor elevation

Sinus membrane elevation with grafting materials and immediate or delayed implant placement

• Indication: Lateral SL with grafting materials is a maxilla with inadequate bone height for implants stability (≤ 5 mm).

• Historically, implants have mainly been placed after initial healing of the graft material (two- stage procedure), although simultaneous implant placement (one-stage procedure) has also been successful. A prerequisite for a one-stage approach is, of course, that initial implant stability can be accomplished.

• Depending on the graft material, different healing times (e.g. 4–10 months) are required. The autogenous graft: 4–6 months. Calcium sulfate and beta-tricalcium phosphate are rapidly dissolved/resorbed. Bioglass: slowly resorbed. Bovine hydroxyapatite, synthetic hydroxyapatites are nonresorbable. If the material resorbs quickly, the volume of the graft will decrease; this needs to be taken into consideration. Placement of implants can be performed earlier in such materials compared with nonresorbable materials because of the slower bone reformation of the latter.

• Membranes to cover the lateral wall: increased bone formation and higher survival rates have been reported.

• The implant failure rate is usually higher during the first year of function.

• In a review, 5,128 implants placed after lateral SL, with follow-up times ranging from 10 to 102 months, were analyzed. Implant survival was 92% autogenous and composite grafts, 93.3% allogeneic/nonautogenous and autogenous/composite grafts, 81% for those placed in alloplast and alloplast/xenograft materials and 95.6% for those placed in xenograft materials alone.

• In a prospective study using composite grafts with either autogenous bone and deproteinized bovine bone mineral, or autogenous bone together with beta-tri- calcium phosphate, the 5-year survival rate was 98%.

• In sinus floor elevation, when autogenous bone is applied alone, the bone height gained can be reduced by as much as 50% by this remodeling. However, it also offers the possibility of a shorter healing time compared with the deproteinized bovine bone mineral graft. However, although deproteinized bovine bone mineral does not activate new-bone formation, as a result of the minimal substitution rate it provides better stability of the graft height.

• Biologic and histologic aspects: The primary purpose of a graft is to function as a scaffold for ingrowth of vessels and cells, starting production of a provisional fibrous connective tissue and subsequently starting the bone reformation. Theoretically, BMP’s, PRP or other bone-stimulating agents could be mixed with autogenous bone in order to act as a catalyser for bone formation, but this is still controversial in the literature.

Sinus membrane elevation and simultaneous implant placement without graft

• Indications: indicated when the amount of residual bone height is adequate for optimal stability.

• The graftless lateral sinus floor elevation technique utilizes simultaneous implant placement and tenting of the sinus membrane.

• Implant survival: Several authors have documented that the mere elevation of the maxillary sinus membrane at the time of implant insertion, with the creation of a void space in which blood-clot formation occurred, resulted in successful bone reformation and implant survival.

• Radiographic measurements: The amount of bone mineralization, as evaluated in periapical radiographs, seemed to increase with time. In general, new bone was more easily distinguished at time points of 1 year and later than at earlier time points

• Complications. Sinus membrane perforation is an intraoperative complication. However, although an intact membrane is desirable, perforation does not seem to prevent bone formation. Bone formation was observed in perforated sites,

• Early exposure of the cover screw is another complication. However, exposure of the cover screw does not seem to lead to increased risk for implant failure, although some marginal bone resorption can be expected.

• Histologic aspects: Boyne showed, spontaneous bone formation.

• Conclusions: The graft less lateral sinus floor elevation technique is a valid alternative tx.

Transcrestal sinus floor elevation Indications

• The transcrestal SL technique has some advantages over the lateral sinus floor elevation procedure, such as less trauma, shorter operation time and less postoperative morbidity.

• A postoperative radiograph should be taken as a baseline for future evaluation of bone healing around the implant.

• Clinical outcomes: Results from a review comprising 19 studies showed an implant survival rate of 95.8% after 5 years. There was a statistically significant difference between implants installed in bone in which the residual bone height was < 5 mm (92.7%) compared with > 5 mm (96.9%). The authors could see no significant difference when grafting material was added compared with lifting the membrane without additional grafting material.

• Comparing the osteotome technique with the lateral window approach, it was shown, in a review comprising 25 papers, that the transcrestal approach had a 97.2% survival rate of the implants followed up to 6 years compared with 93.7% for the lateral window approach.

• Conclusion: The transcrestal sinus floor elevation SL is a less invasive procedure than the lateral window is suitable when the residual height below the maxillary sinus is around 5–8 mm

Indications regarding the residual bone height

• It is proposed that a transcrestal sinus floor elevation approach is considered as the first choice for single tooth gaps in situations with sufficient width for implant placement and a minimal residual bone height of 5 mm.

• Lateral sinus floor elevation with simultaneous implant placement, with or without graft, is indicated when a minimal residual bone height of 3 mm is available and when one or several teeth are to be replaced.

• In situations with a residual bone height of < 3 mm, a lateral sinus floor elevation technique with grafting in a separate session, followed by implant placement after graft healing, should be the technique of choice.

• Concerning impact of implant length, 10 mm is recommended as the minimal length of implant in SL

• In the situation with a staged procedure the amount of residual bone is not of importance, as the appropriate degree of implant stability will be achieved from the new bone formed from the healed graft.