The influence of repeated abutment changes on peri-implant tissue stability: 3-year post-loading results from a multicentre randomised controlled trial.

PURPOSE: To evaluate the influence of at least three abutment disconnections in conventional loaded implants against placement of a definitive abutment in immediately non-occlusal loaded implants on hard and soft tissue changes. A secondary aim was to evaluate whether the presence of less than 2 mm of keratinised mucosa is associated with increased peri-implant marginal bone loss and soft tissue recessions. MATERIALS AND METHODS: Eighty patients requiring one single crown or one fixed partial prosthesis supported by a maximum of three implants were randomised, after implants were placed with more than 35 Ncm, according to a parallel group design to receive definitive abutments that were loaded immediately (definitive abutment or immediate loading group) or transmucosal abutments, which were delayed loaded after 3 months and removed at least three times: 1. At impression taking (3 months after implant placement); 2. When checking the zirconium core on titanium abutments at single crowns or the fitting the metal structure at prostheses supported by multiple implants; 3. At delivery of the definitive prostheses (repeated disconnection or conventional loading group). Patients were treated at four centres and each patient contributed to the study, with only one prosthesis followed for 3 years after initial loading. Outcome measures were: prosthesis failures, implant failures, complications, pink aesthetic score (PES), buccal recessions, patient satisfaction, peri-implant marginal bone level changes and height of the keratinised mucosa. RESULTS: Forty patients were randomly allocated to each group according to a parallel group design. Six patients from the definitive abutment group dropped out or died, and one left from the repeated disconnection group. One implant, from the repeated disconnection group, fractured (difference = 3%; CI 95%: -2%, 8%; P = 1). Four provisional crowns and one definitive single crown had to be remade because of poor fitting, and one definitive crown and one definitive prosthesis because of ceramic and implant fracture, respectively, in the repeated disconnection group vs one provisional prosthesis from the definitive abutment group due to frequent debondings (difference = 15%; CI 95%: 2%, 28%; P = 0.060). Five patients from the definitive abutment group and four patients from the repeated disconnection group were affected by complications (difference = 4%; CI 95%: -11%, 20%; P = 0.725). PES scores assessed at 3 years post-loading were 11.7 (standard deviation = 1.8) mm for the definitive abutment group and 11.3 (1.5) mm for the repeated abutment changes group (difference = 0.4; CI 95%: -0.4, 1.2; P = 0.315). However, there was a difference of 0.26 out of a maximum score of 2 in favour of the definitive abutment group for soft tissue contour only. Buccal recessions at 3 years post-loading amounted to -0.1 (0.8) mm for the definitive abutment group and -0.1 (1.2) mm for the repeated abutment changes group (it was actually a soft tissue gain; difference = 0.01 mm CI 95%: -0.48, 0.50; P = 0.965). All patients declared being very satisfied or satisfied with the function and aesthetics of the prostheses and said they would undergo the same procedure again, with the exception of one patient from the repeated disconnection group who was uncertain regarding function. Mean peri-implant marginal bone loss 3 years after loading was 0.07 (0.18) mm for the definitive abutment group and 0.50 (0.93) mm for the repeated abutment changes group (difference = 0.43 mm; CI 95%: 0.13, 0.74; P = 0.007). The height of keratinised mucosa at 3 years post-loading was 2.8 (1.3) mm for the definitive abutment group and 2.8 (1.6) mm for the repeated abutment changes group (difference = 0.03; CI 95%: -0.67, 0.73; P = .926). Up to 3 years after initial loading there were no statistically significant differences between the two procedures, with the exception of 0.4 mm more marginal bone loss at implants subjected to three abutment disconnections. There were no significantly increased marginal bone loss (difference = 0.1 mm, CI 95%: -0.3, 0.5, P = 0.590) or buccal recessions (difference = 0.1 mm, CI 95%: -0.4, 0.7, P = 0.674) at implants with less than 2 mm of keratinised mucosa at loading. CONCLUSIONS: Three-year post-loading data showed that repeated abutment disconnections significantly increased bone loss of 0.43 mm, but this difference may not be considered clinically relevant; therefore clinicians can use the procedure they find more convenient for each specific patient. Immediately non-occlusally loaded dental implants are a viable alternative to conventional loading and no increased bone loss or buccal recessions were noticed at implants with less than 2 mm of keratinised mucosa. Conflict of interest statement: This trial was partially funded by Dentsply Sirona Implants, the manufacturer of the implants and other products evaluated in this investigation. However, data belonged to the authors and by no means did the manufacturer interfere with the conduct of the trial or the publication of the results, with the exception of rejecting a proposal to change the protocol, after the trial was started, allowing the use of indexed abutments.

Do repeated changes of abutments have any influence on the stability of peri-implant tissues? One-year post-loading results from a multicentre randomised controlled trial.

PURPOSE: To evaluate the influence of at least three abutment changes in conventionally loaded implants against placement of a definitive abutment in immediately non-occlusal loaded implants on hard and soft tissue changes. MATERIALS AND METHODS: Eighty patients requiring one single crown or one fixed partial prosthesis supported by a maximum of three implants were randomised, after implants were placed with more than 35 Ncm, according to a parallel group design to receive definitive abutments which were loaded immediately (definitive abutment or immediate loading group) or transmucosal abutments. These were delayed loaded after 3 months and were removed at least three times: 1) at impression taking (3 months after implant placement); 2) when checking the zirconium core on titanium abutments at single crowns or the fitting the metal structure at prostheses supported by multiple implants; 3) at delivery of the definitive prostheses (repeated disconnection or conventional loading group). Patients were treated in four centres and each patient contributed to the study with only one prosthesis followed for 1 year after initial loading. Outcome measures were: prosthesis failures, implant failures, complications, pink esthetic score (PES), buccal recessions, patient satisfaction, peri-implant marginal bone level changes and height of the keratinised mucosa. RESULTS: Forty patients were randomly allocated to each group according to a parallel group design. Two patients dropped out from the definitive abutment group but no implant failed. Four provisional and one definitive single crowns had to be remade (due of misfitting) and one definitive crown (due to ceramic fracture) in the repeated disconnection group versus one provisional prosthesis of the immediate loading group due to frequent debondings (difference = 12%; CI95%: 0%, 25%; P = 0.109). Eight patients were affected by complications: four patients from each group (difference = 1%; CI95%: -13%, 14%; P = 1). PES scores assessed at 1 year post-loading were 11.4 (1.5) mm for the definitive abutment group and 11.0 (2.0) mm for the repeated abutment changes group (difference = 0.4; CI95%: -0.4, 1.2; P = 0.289). Buccal recessions at 1 year post-loading amounted to 0.07 (0.35) mm for the definitive abutment group and 0.12 (0.65) mm for the repeated abutment changes group (actually it was a soft tissue gain; difference = 0.05 CI 95%: -0.19, 0.29; P = 0.659). All patients declared to be very satisfied or satisfied with the function and aesthetics of the prostheses and would undergo the same procedure again. Mean peri-implant marginal bone loss at 1 year after loading was 0.06 (0.12) mm for the definitive abutment group and 0.23 (0.49) mm for the repeated abutment changes group (difference = -0.16; CI95%: -0.33,-0.00; P = 0.046). The height of the keratinised mucosa at 1 year post-loading was 2.8 (1.5) mm for the definitive abutment group and 2.8 (1.7) mm for the repeated abutment changes group (difference = -0.0; CI 95%: -0.8, 0.7); P = 0.966. Up to 1 year after initial loading, there were no statistically significant differences between the two procedures, with the exception of 0.16 mm more marginal bone loss at implants subjected to three abutment removals. CONCLUSIONS: One-year post-loading data showed that repeated abutment changes significantly increased bone loss of 0.16, but this difference cannot be considered clinically relevant, therefore clinicians can use the procedure they find more convenient for their specific patient. In addition, immediately non-occlusally loaded dental implants are a viable alternative to conventional loading. Conflict-of-interest statement: This trial was partially funded by Dentsply Sirona Implants, the manufacturer of the implants and other products evaluated in this investigation. However, data belonged to the authors and by no means did the manufacturer interfere with the conduct of the trial or the publication of the results with exception of rejecting the proposal of changing the protocol, after the trial was started, allowing the use of indexed abutments.

Do repeated changes of abutments have any influence on the stability of peri-implant tissues? Four-month post-loading preliminary results from a multicentre randomised controlled trial.

PURPOSE: To evaluate the influence of at least three abutment changes against the placement of a definitive abutment, which was no longer removed, on hard and soft tissue changes, and to compare the clinical outcomes of immediate non-occlusal loading versus conventional loading. MATERIALS AND METHODS: Eighty patients requiring one single crown or one fixed partial prosthesis supported by a maximum of three implants were randomised, after implants were placed with more than 35 Ncm, according to a parallel group design to receive definitive abutments which were loaded immediately (definitive abutment or immediate loading group) or transmucosal abutments which experienced delayed loading after 3 months and were removed at least three times: 1) during the making of the impression (3 months after implant placement); 2) when checking the zirconium core of titanium abutments at single crowns or the fitting of the metal structure at prostheses supported by multiple implants; 3) at delivery of the definitive prostheses (repeated disconnection or conventional loading group). Patients were treated in four centres and each patient contributed to the study with only one prosthesis followed for 4 months after initial loading. Outcome measures were: prosthesis/implant failures, any complication, peri-implant marginal bone level changes, and patient satisfaction. RESULTS: Forty patients were randomly allocated to each group according to a parallel group design. No patient dropped-out and no implants failed. However four provisional prostheses and one definitive prosthesis had to be remade because of misfitting (five single crowns) in the repeated disconnection group; and one provisional prosthesis had to be remade because of frequent debondings in the immediate loading group (difference=10%; 95% CI: -1%, 21%; P=0.109). Five complications (all debondings of the provisional prostheses) were reported in two patients of the immediate loading group, in comparison to three biological complications in three patients of the repeated disconnection group (difference=2%; 95% CI: -8%, 13%; P=1). All patients were very satisfied or satisfied with the function and aesthetics of the prostheses, and would undergo the same procedure again. Mean peri-implant marginal bone loss 4 months after loading was -0.08 (0.16) mm for the definitive abutment group and -0.09 (0.20) mm for the repeated abutment changes group (difference=0.01; 95% CI: -0.07, 0.09; P=0.97). There were no statistically significant differences for any of the outcome measures between the two procedures up to 4 months after initial loading. CONCLUSIONS: Preliminary short-term data (4-month post-loading) showed that repeated abutment changes do not alter bone levels significantly. Immediate non-occlusal loading of dental implants are a viable alternative to conventional loading. Therefore clinicians can use the procedure they find more convenient for their specific patient.

Simultaneous sinus augmentation with implant placement: histomorphometric comparison of two different grafting materials. A multicenter double-blind prospective randomized controlled clinical trial.

PURPOSE: Sinus elevation via the lateral approach for implant rehabilitation of atrophic posterior maxillae is considered a safe and predictable therapy. Several xenogeneic biomaterials of different biologic origin have been used as valid and predictable alternatives to autogenous bone. This multicenter randomized controlled double-blind prospective clinical trial aimed to compare histomorphometrically two xenogeneic grafting materials used for sinus elevation with simultaneous implant placement. MATERIALS AND METHODS: Seven private practices in Italy were involved. Patients presenting at least one site with a residual bone crest height between 2 and 4 mm were treated. Control sites were grafted with 100% deproteinated particulated bovine bone (DPBB), while test sites were grafted with prehydrated corticocancellous porcine bone (PCPB). Root-form implants were placed simultaneously. Insertion torque and clinical stability were assessed and recorded. At 6 months, a biopsy specimen was harvested from each site, and histomorphometric analyses were performed. RESULTS: Thirty-seven patients received 42 sinus elevations (24 test and 18 control). Eighty-two implants with adequate primary stability were placed. Fifty-five implants were placed in residual bone crests greater than 2 mm but less than 4 mm (average 2.7 mm) and achieved an average insertion torque of 22.8 ± 11.3 N/cm. Nineteen implants were placed in ridges greater than 3 mm but less than 5 mm, and eight were placed in ridges with more than 5 mm remaining. After 6 months, three implants had failed to integrate, leading to a survival rate of 96.34%. Forty-two specimens were analyzed histomorphometrically. No significant differences in total bone volume (PCPB 37.43%, DPBB 37.52%) or residual grafting material (PCPB 13.55%, DPBB 16.44%) were detected. CONCLUSIONS: In this study, PCPB compared well with DPBB as a grafting material for lateral sinus elevation.

A novel bone scraper for intraoral harvesting: a device for filling small bone defects.

AIM: To evaluate histologically the morphology and characteristics of bone chips harvested intraorally by Safescraper, a specially designed cortical bone collector. MATERIAL AND METHODS: Bone chips harvested near a bone defect or in other intraoral sites were grafted into a post-extractive socket or applied in procedures for maxillary sinus floor augmentation or guided bone regeneration. Core biopsies were performed at implant insertion. Undecalcified specimens embedded in PMMA were studied by histology, histochemistry and SEM. RESULTS: Intraoral harvesting by Safescraper provided a simple, clinically effective regenerative procedure with low morbidity for collecting cortical bone chips (0.9-1.7 mm in length, roughly 100 microm thick). Chips had an oblong or quadrangular shape and contained live osteocytes (mean viability: 45-72%). Bone chip grafting produced newly formed bone tissue suitable for implant insertion. Trabecular bone volume measured on biopsies decreased with time (from 45-55% to 23%). Grafted chips made up 50% or less of the calcified tissue in biopsies. Biopsies presented remodeling activities, new bone formation by apposition and live osteocytes (35% or higher). DISCUSSION AND CONCLUSIONS: In conclusion, Safescraper is capable of collecting adequate amounts of cortical bone chips from different intraoral sites. The procedure is effective for treating alveolar defects for endosseous implant insertion and provides good healing of small bone defects after grafting with bone chips. The study indicates that Safescraper is a very useful device for in-office bone harvesting procedures in routine peri-implant bone regeneration.