Multi-Layer Technique (MLT) with Porcine Collagenated Cortical Bone Lamina for Bone Regeneration Procedures and Immediate Post-Extraction Implantation in the Esthetic Area: A Retrospective Case Series with a Mean Follow-Up of 5 Years.

BACKGROUND: Augmentation of the edentulous atrophic anterior region is a challenging situation. The purpose of this article was to evaluate the effectiveness of a collagenated cortical bone lamina of porcine origin for horizontal ridge augmentation in patients with inadequate alveolar ridge width undergoing immediate post-extraction implantation in the anterior sites, and to report on implant survival rates/complications. MATERIALS AND METHODS: The cases were extracted electronically from a large database according to these specific inclusion criteria: patients with inadequate alveolar ridge width in the anterior maxilla or mandible, who underwent immediate post-extraction implant placement and simultaneous alveolar bone reconstruction using xenogeneic cortical bone lamina. An additional layer of palatal connective tissue graft was inserted between lamina and the vestibular mucosa, for improving soft tissue healing. A collagenated bone substitute was additionally placed in the gap between the lamina and implant surface in all patients. The main outcomes were implant survival and complications. RESULTS: Forty-nine patients with 65 implants were included. Patients' mean age at the time of implant surgery was 60.0 ± 13.6 years. The mean follow-up was 60.5 ± 26.6 months after implant placement. The implant survival was 100%. Four postoperative complications occurred in four patients. No specific factor was found to be associated with complication occurrence. CONCLUSION: The use of collagenated cortical bone lamina can be considered as a successful option for alveolar reconstruction in immediate post-extraction implant insertion procedures in anterior regions with inadequate alveolar ridge width.

Biologic and Technical Complications of Implant-Supported Immediately Loaded Fixed Full-Arch Prostheses: An Evaluation of Up to 6 Years.

PURPOSE: Treatment by means of implant-supported immediately loaded fixed full-arch prostheses is known to be related to biologic and technical complications. The aim of this retrospective study was to investigate the prevalence and moment of occurrence of biologic and technical complications happening in immediately loaded fixed full-arch prostheses. MATERIALS AND METHODS: This study investigated patients who received treatment with immediately loaded fixed full-arch prostheses using four to six implants from 2007 to 2013. The investigation included biologic and technical complications. Complications were depicted regarding their prevalence and their first time of occurrence. Statistical analysis was performed regarding the differences of the mean complication values between the mandible and the maxilla and between technical and biologic complications. RESULTS: The investigation included 482 immediately loaded fixed full-arch prostheses (380 patients, mean observation period: 23.5 months). In 193 arches (40%), either technical (30.9%), biologic (6.5%), or both (3.1%) types of complications occurred. Technical complications occurred significantly more often than biologic complications (P < .000). The most frequent technical complication was "fracture of veneering material" (24.7%, arch level). The most frequent biologic complication was "marginal bone loss ≥ 2 mm" (16.3%, implant level). The median first advents of technical complications were after 23/26 months (implant-/prosthesis-related) and after 3 months for biologic complications, respectively. There was no significant difference of the mean complication rates between the maxilla and the mandible (P = .409). In 99.0% of the arches with complications, the restorations could be obtained. CONCLUSION: Within this treatment concept, biologic and technical complications may occur over time. However, the vast majority of complications (99.0%) do not affect the overall prosthesis survival. Technical complications are assumed to occur significantly more often than biologic complications. It is suggested that not only stress and material fatigue but also function is a matter concerning this treatment option and, thus, may be a factor related to complication rates.

Soft tissue augmentation applying a collagenated porcine dermal matrix during second stage surgery: A prospective multicenter case series.

BACKGROUND: The achievement and preservation of an adequate amount of soft tissue around implants is a critical factor for the prognosis of the treatment. PURPOSE: To evaluate the effectiveness of a porcine dermal matrix applied during second stage implant surgery for horizontal soft tissue augmentation and preservation of dimensional stability. MATERIALS AND METHODS: Twenty patients (mean age 50.2 ± 11.9 [SD] years) candidate to implant therapy and requiring soft tissue augmentation were recruited in four centers. Augmentation was performed in 24 cases. A porcine dermal matrix was placed into a buccal split-thickness pouch during uncovering surgery. Silicone impressions were taken before surgery (T0), 2 weeks later at suture removal (T2), 6 months (T3), and 24 months (T4) post augmentation. Dimensional changes of soft tissue were evaluated using superimposition of digitalized study casts. RESULTS: Nineteen patients (23 implants) could be evaluated at 6 months and 13 patients (17 implants) at 24 months. After 6-month follow-up, there was a significant dimensional gain respect to baseline, averaging 0.83 ± 0.64 mm (P < .01). This did not change significantly at 24 months (0.77 ± 0.65 mm, P = .19). The gain was >0.5 mm in 65.2% and 64.7% of the cases, respectively. Soft tissue shrinkage averaged 34.2% ± 77.0% from T2 to T3 (P < .01) and did not change thereafter (P = .39). Shrinkage was more consistent in the posterior mandible than in the maxilla, but not significantly (P = .23 at 6-month and .36 at 24-month). No adverse events occurred. CONCLUSION: Within the limitations of this prospective case series, the use of a porcine dermal matrix may provide consistent soft tissue augmentation that maintains up to 24-month follow-up, although graft shrinkage may occur in the first 6 months, depending on the location of surgery.

"Teflon tape technique": synergy between isolation and lucidity.

The aim of this article is to introduce and illustrate the "Teflon tape technique," which provides good lucidity in combination with excellent isolation of the working field. It is intended to serve as a supplement to the gold standard rubber dam for the adhesive working dental practitioner. Primarily, the Teflon tape technique (Teflon is a registered trademark, and not affiliated with Teflon tape) is particularly suitable for the adhesive cementation of restorations with very thin margins. It allows free access to subgingival areas with variable gingival retraction. Furthermore, this principle can also be applied to other indications, such as Class V restorations or deep core buildups. The technique described is therefore flexible and easy to use. This combination allows a fast integration of the Teflon tape technique into the daily workflow of the dental practitioner.

Biomechanical aspects: Summary and consensus statements of group 4. The 5th EAO Consensus Conference 2018.

OBJECTIVES: The aim of the present publication was to report on the EAO Workshop group-4 discussions and consensus statements on the five reviews previously prepared. These reviews provided the scientific evidence on the effect of crown-to-implant ratio, on reconstructions with cantilevers in fully and partially edentulous patients, on biological and technical complications of tilted in comparison with straight implants, and on the effects of osseointegrated implants functioning in a residual dentition. MATERIAL AND METHODS: The group discussed, evaluated, corrected where deemed appropriate, and made recommendations to the authors regarding the following five reviews submitted: (a) Is there an effect of crown-to-implant ratio on implant treatment outcomes?; (b) Implant-supported cantilevered fixed dental rehabilitations in fully edentulous patients; (c) and in partially edentulous patients; (d) Biological and technical complications of tilted implants in comparison with straight implants supporting fixed dental prostheses; (e) What are the adverse effects of osseointegrated implants functioning among natural teeth of a residual dentition? Based on the five manuscripts and the discussion among the group as well as the plenum members, the major findings were summarized, consensus statements were formulated, clinical recommendations were proposed, and areas of future research were identified. RESULTS: Crown-to-implant ratios ranging from 0.9 to 2.2 did not influence the occurrence of biological or technical complications also in single-tooth restorations. Reconstructions with cantilevers for the rehabilitation of fully and partially edentulous jaws showed high implant and reconstruction survival rates. In contrast, the rate of complications-in particular associated with veneering material-was high during the observation period of 5-10 years. The data reported were primarily derived from studies with high risk of bias. The data for single-implant reconstructions were small. There was no evidence that distally tilted implants were associated with higher failure rates and increased amounts of marginal bone loss. The data supporting these findings, however, were at high risk of bias and frequently incompletely reported. Frequent positional changes occurred between the natural teeth and the implant-supported restorations. These changes were more pronounced in younger individuals, and even though they were reduced with age, they still occurred in adult patients. Even though these changes were frequent, potential implications for the patient are unclear. CONCLUSIONS: The use of single-tooth restorations with crown-to-implant ratio in between 0.9 and 2.2 may be considered a viable treatment option. Multiunit reconstructions with cantilevers are a viable treatment option in fully and partially edentulous patients. Clinicians and patients should be aware, however, that complications are frequent and primarily related to resin material used for veneering. There is some evidence that tilting an implant does affect stability of the implant and the surrounding bone. Treatment options to tilted implants should carefully be considered, as the effect on soft tissues and on prosthesis behavior is poorly reported for tilted implants. Positional changes in the dentition in relation to implant-supported restorations occur frequently. The patient should be informed about the possible need for a treatment related to these changes in the long term.

Xenogenic collagen matrix or autologous connective tissue graft as adjunct to coronally advanced flaps for coverage of multiple adjacent gingival recession: Randomized trial assessing non-inferiority in root coverage and superiority in oral health-related quality of life.

AIM: To evaluate the non-inferiority of the adjunct of a xenogeneic collagen matrix (CMX) or connective tissue graft (CTG) to coronally advanced flaps (CAF) for coverage of multiple adjacent recessions and compare superiority in patient-reported outcomes (PROM). MATERIAL AND METHODS: One hundred and eighty-seven subjects (92 CMX) with 485 recessions in 14 centres were randomized and followed up for 6 months. Patients filled daily diaries for 15 days to monitor patient-reported experience. The primary outcome was changed in position of the gingival margin. Multilevel analysis used centre, subject and tooth as levels and baseline parameters as covariates. RESULTS: Average baseline recession was 2.5 ± 1.0 mm. The surgery was 15.7 min shorter (95%CI from 11.9 to 19.6, p < .0001) and perceived lighter (11.9 VAS units, 95%CI from 4.6 to 19.1, p = .0014) in CMX subjects. Time to recovery was 1.8 days shorter in CMX. Six-month root coverage was 1.7 ± 1.1 mm for CMX and 2.1 ± 1.0 mm for CTG (difference of 0.44 mm, 95%CI from 0.25 to 0.63 mm). The upper limit of the confidence interval was over the non-inferiority margin of 0.25 mm. Odds of complete root coverage were significantly higher for CTG (OR = 4.0, 95% CI 1.8-8.8). CONCLUSION: Replacing CTG with CMX shortens time to recovery and decreases morbidity, but the tested generation of devices is probably inferior to autologous CTG in terms of root coverage. Significant variability in PROMs was observed among centres.

Implant-Supported Immediately Loaded Fixed Full-Arch Dentures: Evaluation of Implant Survival Rates in a Case Cohort of up to 7 Years.

BACKGROUND: The treatment of severely atrophied and edentulous jaws by means of fixed implant supported solutions is a challenging procedure. PURPOSE: The immediate loading of four to six axial and tilted implants offers the possibility to overcome elaborate hard tissue augmentation procedures but lacks implant and patient related data on implant survival rates. MATERIALS AND METHODS: This retrospective 7-years clinical trial investigated the implant survival rates of 2,081 implants (380 patients, 482 jaws) using an immediate loading protocol with either 4, 5, or 6 implants per restoration. Survival rates were calculated concerning implantation related factors (jaws/number of supporting implants/angulations/diameters/lengths) and patient related factors (medical status/smoking). RESULTS: Overall survival of 2,081 implants was 97.0% on implant level. Survival rates of implantation related factors did not yield significant differences. Significant differences were yield between healthy patients and patients with osteoporosis (p = .002) and the medical status group "other" (p = .032), respectively. Smokers yielded a significantly higher survival than nonsmokers (p = .002). CONCLUSIONS: It is assumed that four implants per jaw serve as a sufficient implant number for full arch restorations in both, the mandible and the maxilla. Osteoporosis under the medication with bisphosphonates seems to be a risk factor for implant survival. The authors suggest that the effect of smoking on ISRs remains controversial within this treatment concept.

Coverage of Multiple Mandibular Gingival Recessions Using Tunnel Technique with Connective Tissue Graft: A Prospective Case Series.

The aim of this clinical case series was to evaluate the clinical performance of the modified tunnel technique for treatment of multiple gingival recessions in the anterior mandible. A total of 20 patients with 63 Miller Class I and II defects were treated via a modified tunnel technique with subepithelial connective tissue graft. At baseline and 6 months postoperative, recession depth, probing pocket depth, width of keratinized tissue, and gingival tissue thickness were assessed. At 6 months, the results revealed a mean recession coverage of 93.87%. Complete recession coverage was achieved in 74.60%. The mean reduction of recession depth was 2.79 ± 0.12 mm. The modified tunnel technique showed successful mean root coverage in the delicate anterior mandible and was able to increase the amount of keratinized tissue.

Zygomatic implant placement in conjunction with sinus bone grafting: the "extended sinus elevation technique." a case-cohort study.

PURPOSE: The zygomatic implant is mainly indicated for the rehabilitation of extremely atrophied maxillae when bone augmentation should be avoided. One drawback of zygomatic implants, which typically pass through the sinus, is initial or late bone resorption around the implant neck, which can result in oroantral communications followed by possible infection of the sinus. To decrease the risk of sinus infection, a modified technique was developed to preserve the integrity of the sinus membrane and to regenerate bone around zygomatic implants using an extended sinus grafting approach. MATERIALS AND METHODS: Patients with extremely atrophied maxillae were provided with one to four zygomatic implants in conjunction with sinus grafting, plus conventional auxiliary implants, for immediate support of a provisional full-arch maxillary prosthesis. Definitive prostheses were delivered at 6 months after implant placement. All patients underwent clinical and radiographic examinations at 6 months. RESULTS: Twenty-two zygomatic and 23 conventional auxiliary implants were placed in 10 patients. The overall 6-month implant survival rate was 90.9% for zygomatic implants and 100% for auxiliary implants placed in the anterior area. Only two minor technical complications were seen, and clinical indicators (including probing pocket depth, keratinized tissue, and plaque and bleeding indices) were good in all patients. A substantial gain of radiographic bone around the zygomatic implants was observed. CONCLUSION: The proposed technique led to successful prosthetic function for all patients. With the described technique, exposed implant threads within the maxillary antrum are eliminated and the potential for biologic complications is minimized.

The bone lamina technique: a novel approach for lateral ridge augmentation--a case series.

The goal of this case series is to present a novel treatment approach for lateral ridge augmentation. Four systemically healthy patients (aged 48 to 59 years) with inadequate dental alveolar ridge widths were selected for inclusion. All ridge defects were augmented using a xenogeneic cortical bone shield in combination with particulated bone substitutes and a thin collagen barrier. At baseline and after 6 months, digital cone beam computed tomography scans were performed. Biopsy specimens were harvested at reentry surgery and processed for histologic analysis. The results revealed a sufficient amount of bone structure for implant placement without additional augmentation procedures. The histologic analysis demonstrated that new bone formation had taken place and the bone shield had resorbed entirely. This case series indicates that the bone lamina technique has the biologic and mechanical properties to successfully achieve hard tissue augmentation of deficient ridges.

Dimensional alterations of extraction sites after different alveolar ridge preservation techniques - a volumetric study.

OBJECTIVES: The aim of this randomized controlled clinical study was to assess soft tissue contour changes after different alveolar ridge preservation procedures. MATERIAL AND METHODS: Following tooth extraction, 30 patients were randomly assigned to the following treatments (Tx) - Tx 1: xenogenic bone substitute (pre-hydrated collagenated cortico-cancellous porcine bone) and free gingival graft; Tx 2: free gingival graft alone; Tx 3: xenogenic bone substitute; Tx 4: no further treatment (control). Impressions were obtained before tooth extraction (baseline) and 4 months after surgery. Cast models were optically scanned, digitally superimposed and horizontal measurements of the contour alterations between time points were performed using digital imaging analysis. RESULTS: All groups displayed contour shrinkage at the buccal aspect ranging from a mean horizontal reduction of -0.8 ± 0.5 mm (Tx 1) to -2.3 ± 1.1 mm (control). Statistically significant differences were found between Tx 1 and Tx 4 as well as Tx 2 and Tx 4. A significant positive influence of the free gingival graft on the maintenance of the ridge width was recorded (p < 0.001). CONCLUSION: In this study, alveolar ridge preservation techniques were not able to entirely compensate for alveolar ridge reduction. Covering the orifice of the extraction socket with a free gingival tissue graft seems to have the potential to limit but not avoid the post-operative external contour shrinkage based on optical scans.

The Healing of Free Gingival Autografts for Socket-seal Surgery: a Case Report.

Tooth extraction will be followed by marked alterations to the tissue volume, in particular in the anterior zone, which may jeopardize the esthetic outcome of any dental treatment involving tooth extraction. If, however, ridge collapse can eb prevented or minimized after tooth extraction, more predictable outcomes with superior esthetics can be accomplished along with fewer surgical procedures. Therefore, it was proposed that stabilizing the soft tissue architecture with a free gingival graft could minimize the soft tissue shrinkage. The following case report describes some surgical modifications and refinements in order to enhance the predictability of the socket-seal surgery.

Immediate loading of fixed provisional prostheses using four implants for the rehabilitation of the edentulous arch: a prospective clinical study.

PURPOSE: The purpose of this prospective clinical trial was to evaluate over a 5-year period the treatment outcomes for immediately loaded full-arch fixed prostheses supported by two axially inclined and two tilted implants used to rehabilitate edentulous arches. This report presents preliminary 1-year results. MATERIALS AND METHODS: Thirty-seven patients were recruited for treatment with either mandibular or maxillary full-arch fixed prostheses supported by four implants. Within 24 hours, the implants were immediately loaded with screw-retained full-arch acrylic resin provisional restorations. Definitive reconstructions were delivered 6 months later. Complete full-arch prostheses were supported by metal frameworks combined with high-density acrylic resin. Follow-up visits were scheduled for 6 and 12 months after initial prosthetic loading and then annually for up to 5 years. Digital radiographs were obtained immediately, 6 months after surgery, and at each annual follow-up visit. Marginal peri-implant bone levels were assessed using digital image analysis. RESULTS: The 1-year implant survival rates were 96.0% for axially positioned implants and 94.6% for tilted implants. The survival rates were 96.6% for maxillary implants and 98.7% for mandibular implants. The prosthetic survival rate was 100%. No significant differences were found in the results for tilted versus axially positioned implants. One year after loading, the mean marginal bone loss was 0.82 ± 0.31 mm around the axially oriented implants and 0.76 ± 0.49 mm around the tilted implants (P ⋜ .05). CONCLUSIONS: Preliminary data from this clinical trial show high implant survival rates for immediately loaded full-arch prostheses supported by four implants. Immediate loading of tilted implants may be considered a viable treatment option for the rehabilitation of edentulous patients.

Hard tissue alterations after socket preservation with additional buccal overbuilding: a study in the beagle dog.

OBJECTIVES: The aim of this study was to histometrically assess alterations of the ridge following socket preservation alone and socket preservation with additional buccal overbuilding. MATERIAL AND METHODS: In five beagle dogs four extraction sites were randomly subjected to one of the following treatments: Tx 1: The socket was filled with BioOss Collagen and covered with a free gingival graft from the palate. Tx 2: The buccal bone plate was augmented using the GBR-technique, the socket was filled with BioOss Collagen and covered with a free gingival graft. Tx 3: The buccal bone plate was forced into a buccal direction using a manual bone spreader. The socket was filled with BioOss Collagen and covered with a free gingival graft from the palate. Tx 4: The socket was filled with BioOss Collagen and a combined free gingival/connective tissue graft was used to cover the socket and for buccal tissue augmentation. For each experimental site, two histological sections were subjected to histometric analysis and evaluated for (i) vertical bone dimensions and (ii) horizontal bone dimensions. RESULTS: All treatment groups showed horizontal and vertical bone loss. The mean vertical bone loss of the buccal bone plate was significantly lower in Tx 4 than in the other groups, while no statistical significant differences could be detected among the groups in the horizontal dimension. CONCLUSION: Overbuilding the buccal aspect in combination with socket preservation does not seem to be a suitable technique to compensate for the alterations after tooth extraction.

The double split flap: a surgical approach for regenerative treatment of interproximal defects.

AIMS AND BACKGROUND: Primary wound closure has been advocated to be indispensable for a successful outcome of guided tissue regeneration-procedures. Yet narrow inter-proximal spaces often lack sufficient tissue quantity in order to facilitate a tension free re-adaptation of periodontal flaps. In order to maintain an uneventful healing process, the concept of layer-wise wound closure is applied to periodontal surgery. MATERIAL AND METHOD: This article describes the introduction of a modified flap design, the double split flap. RESULTS AND CONCLUSION: By preparation of a second, internal flap and a wound in a layer-wise fashion, it is assumed that primary healing will be more predictable to achieve.

The friction free osteotome technique: introduction of a modified approach.

The current literature suggests that the bone-condensing approach while performing internal sinus floor elevation may not be beneficial for the future implant site. Furthermore, even with refined procedures, a predictable and controlled infraction of the sinus floor prior to graft placement still seems to be technique sensitive. In this context, the present article presents a modified technique along with the use of parallel osteotomes devoid of any contact to the lateral osteotomy wall. Therefore, compression of the adjacent bone will be avoided and the tactility of the site for the surgeon will be preserved as the osteotome is solely in contact with the subsinus cortex.

Microsurgical access flap in conjunction with enamel matrix derivative for the treatment of intra-bony defects: a controlled clinical trial.

OBJECTIVES: The aims of this controlled study were to clinically and radiographically evaluate the effect of a microsurgical approach for the treatment of intra-bony defects with and without an enamel matrix derivative (EMD). Parts of this study population were already published by Wachtel and colleagues in 2003. MATERIAL AND METHODS: Seventy intra-bony defects were randomly assigned to a microsurgical access flap with application of EMD (test group) and on the contra-lateral side to a microsurgical access flap alone (control group). Clinical and radiographic parameters were assessed at baseline and after 6 and 12 months. RESULTS: Both test and control treatments resulted in a statistically significant mean clinical attachment level (CAL) gain, probing pocket depth (PPD) reduction and radiographic bone fill. The test group yielded statistically significantly more CAL gain, PPD reduction and radiographic bone fill than the control group. Gingival recession increase after 12 months averaged 0.5 and 0.7 mm for the test and control groups, and did not reach statistical significance. Two weeks after surgery, primary wound closure was maintained in 91% of the test sites and 97% of the control sites. CONCLUSION: The combination of a microsurgical access flap with EMD seems to be superior to open flap debridement in terms of PPD reduction, CAL gain and radiographic bone fill. In the test as well as the control group, primary wound closure was successfully achieved.

Hard tissue alterations after socket preservation: an experimental study in the beagle dog.

OBJECTIVES: The aim of the following experimental study was to assess bone changes in the horizontal and vertical dimension when using different socket preservation procedures. MATERIAL AND METHODS: In five beagle dogs the distal roots of the 3rd and 4th premolar were extracted without elevation of a mucoperiosteal flap and the following treatments were assigned: Tx 1: The extraction socket was filled with BioOss Collagen (Geistlich Biomaterials, Wolhusen, Switzerland) and interrupted sutures were applied.: Tx 2: The extraction socket was filled with BioOss Collagen (Geistlich Biomaterials, Wolhusen, Switzerland) and a free gingival graft was sutured to cover the socket.: Tx 3: The extraction socket was left with its blood clot and interrupted sututes were applied.: Four month after surgery the dogs were sacrificed and from each extraction site two histological sections were selected for histometric analysis. The following parameters were evaluated: (1) the vertical dimension was determined by placing a horizontal line on the lingual bone wall. Then, the distance from this line to the buccal bone wall was measured. (2) The horizontal dimension was assessed at three different areas measured from the top of the lingual crest: 1 mm (Value 1), 3 mm (Value 3) and 5 mm (Value 5). RESULTS: The mean vertical loss of the buccal bone plate for the Tx 1 group was 2.8+/-0.2 mm. The Tx 2 group showed vertical loss of 3.3+/-0.2 mm. The Tx 3 group demonstrated 3.2+/-0.2 mm of mean vertical loss. The horizontal dimension of the alveolar process was 4.4+/-0.3/6.1+/-0.2/7.2+/-0.1 mm at the three different levels for the Tx 1 group. The Tx 2 group depicted bone dimensions of 4.8+/-0.2/6.0+/-0.2/7.1+/-0.1 mm. The horizontal dimension of the Tx 3 group was 3.7+/-0.3/6.2+/-0.2/7.0+/-0.1 mm. When the results from the horizontal measurements were tested with the analysis of variance (ANOVA), a clear significance could be found in particular for Value 1 mm between the test groups Tx 1 and Tx 2 and the control group (Tx 3) (P<0.001). Furthermore the mean of treatment 1 (Tx 1) was slightly significantly lower than of treatment 2 (Tx 2) (P<0.05). CONCLUSION: The findings from the present study disclose that incorporation of BioOss Collagen into the extraction socket has only limited impact on the subsequent biologic process with particular respect to the buccal bone plate. The horizontal measurement of the alveolar ridge depicted that the loss of the buccal bone plate was replaced to a certain amount by newly generated bone guided by the BioOss Collagen scaffold. It seems that the mechanical stability provided by BioOss Collagen and furthermore by a free gingival graft could act as a placeholder preventing the soft tissue from collapsing.

Dimensional changes of the alveolar ridge contour after different socket preservation techniques.

OBJECTIVES: The aim of the following study was to assess contour changes after socket preservation techniques. MATERIAL AND METHODS: In five beagle dogs, the distal root of the third and fourth mandibular premolars was extracted. The following treatments (Tx) were randomly assigned for the extraction socket. Tx 1: BioOss Collagen. Tx 2: BioOss Collagen and a free soft tissue graft. Tx 3: No treatment. Tx 4: The internal buccal aspect was covered with an experimental collagen membrane, the extraction socket was filled with BioOss Collagen and the membrane folded on top of the graft. Impressions were obtained at baseline, 2 and 4 months after surgery. Bucco-lingual measurements were performed using digital imaging analysis. RESULTS: All groups displayed contour shrinkage at the buccal aspect. Only the differences between the two test groups (Tx 1, Tx 2) and the control group (Tx 3) were significant at the buccal aspect (p< or =0.001). No measurements of the Tx 4 group could be performed. CONCLUSION: Socket preservation techniques, used in the present experiment, were not able to entirely compensate for the alterations after tooth extraction. Yet, incorporation of BioOss Collagen seems to have the potential to limit but not avoid the post-operative contour shrinkage.