Prognosis of Deantigenated Equine Bone Used for Bone Augmentation: A Multicenter Retrospective Study on Early and Late Postsurgical Complications in 81 Consecutive Patients.

PURPOSE: To evaluate the clinical outcome of deantigenated equine bone (DEB) grafts in a series of patients treated with DEB at six months postaugmentation. MATERIALS AND METHODS: One hundred DEB grafts were inserted in 81 patients between January 2004 and December 2006. Thirty-two DEBs were blocks and 68 were granules (52 sinus lift and 16 guided bone regeneration [GBR] procedures performed). A total of 147 implants were inserted. A Pearson chi-square test was used to detect any statistically significant correlation between the studied variables and early and/or late failures. RESULTS: There were 6 early and 26 late graft failures and another 16 failures after prosthesis placement. The overall failure rate was 25% in the GBR procedures, 31.9% in sinus lift, and 54.3% with blocks, for a total complication rate of 39.5%. A statistically significant relation was detected with respect to graft type and early complications (p = .005), with a worse outcome for DEB blocks compared to granules. After provisional prosthesis restoration, 23 implants were lost, and another 41 failed after definitive prosthesis delivery, for an overall failure rate of 43.5%. The follow-up period was 3 years after surgery. CONCLUSIONS: DEB grafting material had a very high rate of complications. Blocks had more than 50% failures, mainly in the immediate postoperative period. Other procedures such as GBR and sinus lift also showed more than 25% infections and resorption, and late failures (i.e., after-implant placement) were also common. Our results show that DEB is less than ideal for crestal bone reconstruction.

Statements and Recommendations for Guided Bone Regeneration: Consensus Report of the Guided Bone Regeneration Symposium Held in Bologna, October 15 to 16, 2016.

INTRODUCTION: In the past 10 years, long-term studies have demonstrated that guided bone regeneration (GBR) is a successful and reliable technique for vertical and horizontal ridge augmentation, but strict and rigorous protocols must be adopted. MATERIAL AND METHODS: Because no reports have yet been published with statements and clinical recommendations for GBR, a closed meeting of all authors was organized to discuss this matter during a GBR symposium held in Bologna (Italy) in October 2016. The authors focused on the findings of systematic and narrative reviews, prepared before the meeting, covering aspects of the clinical management of GBR techniques. Successively, a discussion based on the scientific evidence and on the experts' opinions led to the formulation of statements, clinical recommendations, and implications for future research. RESULTS: To avoid complications and to optimize outcomes, the following factors should be considered by clinicians: patient selection; analysis of defect type; blood supply; antibiotic treatment; flap passivation; delayed implant placement; combination of autogenous bone and xenograft or allograft; rigorous fixation of membranes; removal after 6 to 9 months; analysis of complications; soft-tissue management; and high care in scarred sites and in esthetic areas. CONCLUSIONS: The present consensus report reviewed the scientific evidence and provided specific guidelines and recommendations for clinical practice and the different approaches to GBR techniques to ensure surgical success and predictable outcomes.

On the role of keratinised mucosa at dental implants: a 5-year prospective single-cohort study.

PURPOSE: The purpose of this study was to evaluate the role of keratinised mucosa on the long-term success of dental implants. MATERIALS AND METHODS: Thirty-two edentulous patients had one of their dental arches rehabilitated with a provisional screw-retained resin reinforced cross-arch fixed prosthesis supported by four immediately loaded implants. The two central straight implants were randomly allocated in two equal groups, according to a parallel-group design, to receive or not intermediate abutments (Multi-Unit Abutment, MUA). However, for the purpose of the present publication, the study was considered as a prospective single cohort study. To be immediately loaded, implants had to be inserted with a minimum torque of 30 Ncm, which was achieved by all implants. Provisional prostheses were delivered within 24 hours and were replaced, after 4 months, by definitive screw-retained metal-ceramic prostheses. Patients were followed up to 5 years after loading. Prostheses were removed every 8 months to facilitate professionally delivered maintenance. Outcome measures were prosthesis and implant failures, complications, peri-implant marginal bone level (MBL) changes, bleeding on probing (BoP) and keratinised mucosa height (KMH). The absence of vestibular or lingual keratinised mucosa was put in relation with peri-implant bone loss and BoP. RESULTS: Five-years after loading two patients dropped out and no implant or prosthetic failure occurred. Four patients were affected by prosthetic complications. At delivery of definitive prostheses, 32 (25%) implants had at least one vestibular or lingual site with no KMH and 96 (75%) implants had both sites with some KMH. Multi-level models did not show any statistically significant association between KMH at the time of delivery of the definitive prosthesis and changes in MBL and BoP at 5 years (estimate = 0.02; 95% CI: -0.02 to 0.05; P = 0.3393; and 1.02; 95% CI: 0.79 to 1.33; P = 0.8695, respectively). When KMH was analysed as dichotomous variable, implants with presence of KMH at delivery of definitive prosthesis at both vestibular and lingual aspects showed a trend of less BoP (estimate = -0.8; 95% CI: -1.69 to 0.08; P = 0.0741) but a statistically significant greater MBL loss compared to implants where KMH was only present at one site (estimate = 0.18; 95% CI: -0.1 to 0.3; P = 0.0041). CONCLUSIONS: The 5-year after loading outcome of immediately loaded screw-retained cross-arch prostheses supported by four implants is excellent in both the maxilla and mandible. Although the height of the keratinised mucosa did not seem to alter the clinical outcomes, its presence both at vestibular and lingual sites was associated with an increased marginal bone loss when compared to implants having at least one side without keratinised mucosa.

Do we need abutments at immediately loaded implants supporting cross-arch fixed prostheses? Results from a 5-year randomised controlled trial.

PURPOSE: To compare the clinical outcome (in particular of marginal peri-implant bone level changes) between immediately loaded straight implants which had definitive abutments placed at implant placement and never removed versus implants which had no intermediate abutments. MATERIALS AND METHODS: Thirty-two edentulous patients had one of their jaws rehabilitated with a provisional screw-retained resin reinforced cross-arch fixed prosthesis supported by four immediately loaded implants: two central straight implants and two either tilted or straight distal implants. The two central straight implants were randomly allocated in two equal groups to receive or not an intermediate abutment (Multi-Unit Abutment, MUA) according to a parallel group design. To be immediately loaded implants had to be inserted with a minimum torque of 30 Ncm, which was achieved by all implants. After 4 months, definitive screw-retained metal-ceramic prostheses were delivered and patients were followed-up to 5 years after loading. Prostheses were removed every 8 months to facilitate professionally delivered maintenance. Outcome measures were prosthesis and implant failures, complications, peri-implant marginal bone level changes and bleeding on probing (BoP). RESULTS: Five-years after loading one patient dropped out from each group. No implant or prosthetic failure occurred. Three patients of the abutment group versus one of the no-abutment group were affected by complications (risk difference = 0.125; 95% CI: -0.13 to 0.37; Fisher exact test, P = 0.600). At 5 years, both groups lost marginal bone in a statistically significant way (0.32 ± 0.40 mm for patients of the abutment group and 0.35 ± 0.29 mm for patients of the no-abutment group), with no difference in bone loss between groups at patient levels (difference = 0.03 mm; 95% CI: -0.23 to 0.29 mm; P = 0.809). At 5 years, BoP was significantly higher in the no-abutment group than in the abutment group (difference between medians = 25%; 95% CI: 12.5% to 25%; P < 0.001). By considering only the average of the two central study implants per patient with and without intermediate abutments, there were no differences in bone loss (difference: -0.05 mm; 95% CI: -0.41 to 0.31 mm; P = 0.763), while marginal bleeding was significantly higher in the no-abutment group (difference between medians = 25%; 95% CI: 0% to 50%; P = 0.004). CONCLUSIONS: The present results suggest that intermediate abutments may not be needed at immediately loaded cross-arch screw-retained prostheses, unless there is the necessity to correct implant angulation.

A prospective, randomized, controlled, multicenter evaluation of extraction socket preservation comparing two bovine xenografts: clinical and histologic outcomes.

The aim of this prospective, randomized, controlled, multicenter study was to evaluate and compare the histologic and histomorphometric aspects of extraction sockets grafted with two commercially available bovine bone xenografts: Endobon (test group) and Bio-Oss (control group). The study was designed to ensure that baseline variables between groups were as similar as possible to allow for a direct comparison of graft healing characteristics. Thirty-eight patients contributed 62 augmented extraction sites to the study. All sites were grafted with one type of bovine bone mineral and covered with a resorbable collagen membrane for 6 months of healing prior to implant placement surgery. The histologic outcomes between the two treatment groups are similar, with de novo bone (mean ± SD) for the test group at 28.5% ± 20% and for the control group, 31.4% ± 18%. Histologic specimens also include membrane remnants. All but two implants integrated successfully after 1 year of follow-up. This investigation provides support for the efficacy of bovine bone xenograft for socket preservation when subsequent implant placement is planned.

Histologic and biomechanical evaluation of the effects of implant insertion torque on peri-implant bone healing.

The aim of this study was to evaluate histologically and biomechanically the peri-implant bone healing around implants placed with high torque after a follow-up of 8 and 12 weeks. A total of 12 implants were placed in the lower edge of the mandible of 2 sheep. In each sheep, 3 implants were placed with a low torque (<25 N · cm, LT group) as a control, and 3 implants were placed with a high insertion torque (maximum torque, HT group). The sheep were killed after 8 and 12 weeks of healing, and the implants were examined for removal torque, resonance frequency analysis, and histologic analysis.The mean insertion torque in the LT group was 24 N · cm, whereas it was 105.6 N · cm in HT. All the implants osseointegrated and histologic analysis showed similar aspects of the peri-implant bone tissue for both groups and both healing times. Mean removal torque values for LT implants were 159.5 and 131.5 N · cm after 8 and 12 weeks, respectively, whereas those for the HT were 140 and 120 N · cm at 8 and 12 weeks, respectively. Implant stability quotient values were 26.6 and 76 for the LT group and 74 and 76 for the HT group at 8 and 12 weeks, respectively.It could be concluded that high implant insertion torque does not induce adverse reaction in cortical bone and does not lead to implant failure.

High versus low implant insertion torque: a histologic, histomorphometric, and biomechanical study in the sheep mandible.

PURPOSE: The purpose of this study was to analyze, in an animal model, the histologic and biomechanical phenomena at the bone-implant interface of implants inserted with high torque (HT) as compared to low torque (LT) during the first 6 weeks of healing. MATERIALS AND METHODS: Forty tapered-screw-form implants were placed in five hybrid sheep. The implant sites were placed in the mandible, using an extraoral approach; four were placed with HT (test: mean 110 Ncm) on one side and four were placed with LT (control: mean 10 Ncm) on the contralateral side. After 1, 2, 3, 4, and 6 weeks of healing, removal torque testing and resonance frequency analysis were performed and the animals were sacrificed for histologic examination. RESULTS: Implants from the HT group showed significantly higher bone apposition than implants from the LT group at all examined healing times. Similarly, removal torque was consistently higher for the HT as compared to the LT group. A significant loss of primary stability in the HT group was evident 7 days after placement. Implants from the LT group achieved a significant increase in stability after 4 weeks. Resonance frequency analysis was unable to detect these histologic and biomechanical modifications of the bone-implant complex. CONCLUSIONS: The results of the study showed that high implant insertion torque in dense cortical bone does not induce bone necrosis or implant failure, but it does increase the primary stability of implants, which is extremely important in immediate loading protocols.

Effectiveness of prophylactic antibiotics at placement of dental implants: a pragmatic multicentre placebo-controlled randomised clinical trial.

PURPOSE: To evaluate the efficacy of prophylactic antibiotics for dental implant placement. MATERIALS AND METHODS: Thirteen dentists working in private practices agreed to participate in this trial, each centre providing 50 patients. One hour prior to implant placement, patients were randomised to take orally 2 g amoxicillin or identical placebo tablets. Patients needing bone augmentation at implant placement were not included. Outcome measures were prosthesis and implant failures, adverse events and post-operative complications. Patients were seen 1 week, 2 weeks and 4 months post-operatively. RESULTS: Two centres did not deliver any data, two centres did not manage to include the agreed quota of patients and three patients had to be excluded. Two-hundred and fifty-two patients were evaluated in the antibiotic group and 254 in the placebo group, and none dropped out at 4 months. Four prostheses and seven implants (in five patients) failed in the antibiotics group versus 10 prostheses and 13 implants (in 12 patients) in the placebo group. Eleven complications were reported in the antibiotic group versus 13 (in 12 patients) in the placebo group. No side effects were reported. There were no statistically significant differences for prosthesis failures, implant losses and complications. Patients receiving immediate post-extractive implants had an increased failure risk compared with patients receiving delayed implants (9% versus 2%). CONCLUSIONS: No statistically significant differences were observed, although trends clearly favoured the antibiotic group. Immediate post-extractive implants were more likely to fail.

Early loading of implants in vertically augmented bone with non-resorbable membranes and deproteinised anorganic bovine bone. An uncontrolled prospective cohort study.

CONFLICT OF INTEREST: All materials used in this study were purchased by the author and it is therefore free of any commercial or institutional interest. PURPOSE: To evaluate the success rate 1 year after loading of early loaded implants placed in vertically augmented bone using deproteinised bovine bone (Bio-Oss) and a titanium-reinforced membrane (Gore-Tex). MATERIALS AND METHODS: Twenty patients provided 25 sites that were treated with vertical guided tissue regeneration (GBR) using Bio-Oss and expanded polytetrafluoroethylene titanium-reinforced membranes. After 1 year of healing, the membranes were removed and 64 implants were placed (baseline) and loaded 30 days later. Standardised periapical radiographs were obtained at baseline and 1 year thereafter. One independent assessor clinically evaluated the amount of tissue regenerated and peri-implant bone level based on the radiographs. Outcome measures were prosthesis success, implant success, complications, amount of vertically regenerated bone, peri-implant marginal bone levels and histology. RESULTS: No patient dropped out. A total of 23 out of 25 sites healed uneventfully. Two sites showed early membrane exposure. In these sites, the surgery was repeated with success 2 months later. Clinical evaluation showed a mean vertical bone defect of 5.6 mm (SD 1.7). Mean vertical bone gain after GBR was 5.2 mm (SD 1.5). The histology of five samples retrieved from four patients showed a total percentage of xenograft and new bone of 52.6%, with dispersed graft particles surrounded by layers of bone. All implants were stable after 1 year of function, yielding a survival rate of 100%. Statistically significant peri-implant bone loss (0.95 mm; SD 0.21; 95% confidence interval 0.85 to 1.05; P < 0.001) was observed radiographically from baseline to the 1-year follow-up. CONCLUSIONS: This prospective cohort study shows that by using deproteinised bovine bone and a non-resorbable titanium-reinforced membrane, vertical bone gain can be obtained and implants can be loaded after 30 days. The vertical regenerated tissue exhibited good stability over 1 year of implant function.

Efficacy of prophylactic antibiotics for dental implants: a multicentre placebo-controlled randomised clinical trial.

PURPOSE: To evaluate the efficacy of prophylactic antibiotics for dental implant placement. MATERIALS AND METHODS: Twelve Italian private practices agreed to participate in this trial, each centre providing 30 patients. One hour prior to implant placement, patients were randomised, for consumption orally of 2 g amoxicillin or identical placebo tablets. Patients needing bone augmentation procedures were not included. Outcome measures were prosthesis and implant failures, adverse events and post-operative biological complications. Patients were seen 1 week, 2 weeks and 4 months post-operatively. RESULTS: One centre did not deliver any data and 14 patients had to be excluded from the trial for various reasons. One hundred and fifty-eight patients were evaluated in each group and none dropped out at 4 months. Two prostheses and two implants failed in the antibiotics group, compared with four prostheses and nine implants in the placebo group. There were no statistically significant differences for prosthesis failures, implant losses, complications and side effects. CONCLUSIONS: No statistically significant differences were observed. However, four times more patients in the placebo group experienced implant failures than in the antibiotic group, and this requires further investigation.

Histomorphometric evaluation of six dental implant surfaces after early loading in augmented human sinuses.

This study investigated the bone-to-implant contact (BIC) and osteoconductive capacity (OC) of 6 different implant surfaces after early loading in humans. Two implants with different surfaces were placed side-by-side in the grafted (n= 5) and nongrafted (n = 1) sinuses of 3 volunteers. Single-tooth restorations were delivered 60 days later. After 6 months of full occlusal loading, implants were retrieved in block sections for histomorphometric analysis. One implant (acid etched) placed in grafted bone failed when loaded. There were no other complications. In grafted bone, the microtextured surface achieved the highest BIC value (94.08%), followed by the oxidized (77.32%), hydroxyapatite (HA) (74.51%), sandblasted and acid-etched (51.85%), and titanium plasma-sprayed (TPS) (41.48%) surfaces. In native bone, the acid-etched surface achieved a higher BIC value (69.03%) than the HA surface (59.03%). The highest OC value in grafted bone was exhibited by the microtextured surface (34.31%), followed by the HA (28.62%), sandblasted and acid-etched (25.08%), oxidized (17.55%), and TPS (-20.47%) surfaces. The HA surface exhibited a higher OC value (30.39%) in native bone compared with the acid-etched surface (24.0%). As a whole, highest BIC and OC values were exhibited by the microtextured surface, and lowest values were exhibited by the TPS surface. All other surfaces demonstrated excellent BIC (>50%) but varied in OC (range = 17.55%-28.62%). These findings are tempered by the limited scope and sample size of the study and should be considered preliminary. More research is needed to determine the impact of implant surface texture on BIC and OC.

Bone mineral density and bone histomorphometry are statistically related.

PURPOSE: The aim of this study was to evaluate how closely analysis of bone quality performed using the bone mineral density (BMD) values obtained by quantitative computerized tomography (QCT) reflected the histologic bone density. MATERIALS AND METHODS: Eighteen patients requiring implant therapy underwent CT scanning. Their data were processed using Image Master software, and the BMD was calculated by measuring the Hounsfield units and relating those values to a phantom (Calibration Phantom, Quantitative Technologies). Each patient wore a radiographic-surgical template in which titanium cylinders were placed as a drilling guide for preparation of the implant site. The mouth regions where the titanium guides were placed (on the CT images and in the patient's mouth) corresponded to the implant sites where the BMD was measured and where tissue specimens for histomorphometric analysis retrieved. Forty specimens measuring 6 mm in length and 2 mm in diameter were obtained. Histomorphometric analysis was performed by digitizing the images, which were subsequently analyzed using the image analysis software IAS 2000. The bone volume (BV) was calculated as a percentage by dividing the area occupied by the mineralized bone over the entire microscopic field. RESULTS: The results of the statistical analysis showed a Pearson correlation coefficient of 0.691 between the BV and BMD values, with a P value < 0.01, which was considered significant. DISCUSSION AND CONCLUSION: The results of this study support the use of QCT to assess the bone quality before implant placement to improve the planning of implant treatment.

Bone-to-implant apposition with machined and MTX microtextured implant surfaces in human sinus grafts.

The goal of this study was to histologically document the effect of two different implant surfaces on the percentage of bone-to-implant apposition achieved with implants placed in human sinus grafts. The influences of implant site and post-grafting delay time were also examined. Nine healthy volunteers were scheduled to undergo posterior maxillary sinus floor augmentation in preparation for delayed implant placement. In addition to the conventional dental implants selected for each case, titanium alloy experimental implants, 2.5 mm in diameter and 8 mm in length, were custom manufactured. Each microimplant was prepared longitudinally with two different surface topographies: machined on one side and MTX microtextured on the other side. A notch prepared across the superior aspect of the implants facilitated placement and provided a reference line between the two surfaces. Patients were divided into two groups that received the experimental microimplants at the time of conventional implant placement: Group A (six patients) received the experimental microimplants in the regenerated lateral wall of the sinus graft 11 months after graft placement, and group B (three patients) received them in the alveolar crest 6 months after graft placement. After 6 months of submerged healing, all experimental and conventional implants appeared to be clinically osseointegrated. Histologic analysis revealed that the mean bone-to-implant apposition was significantly greater with MTX (72.31% +/- 17.76%) compared to machined surfaces (38.01% +/- 19.32%), regardless of bone quality. The healing time between graft and implant placement and implant location did not statistically impact the percentage of bone-to-implant apposition.