A narrative review on the use of autologous platelet concentrates during alveolar bone augmentation: Horizontal (simultaneous/staged) & vertical (simultaneous/staged).

This review aimed to answer the general question of whether autologous platelet concentrates (APCs, an autologous blood-derivative) can improve the outcome of alveolar bone augmentation. Three clinical scenarios were assessed: horizontal/vertical bone augmentation in combination with implant placement (simultaneous approach), horizontal bone augmentation in a staged approach, and vertical bone augmentation in a staged approach. An electronic literature search strategy was conducted for each review from the outset to July 1st, 2023. The titles and abstracts (when available) of all identified studies were screened and imported into a database. If articles appeared to meet the inclusion criteria or their title and abstract had insufficient data, the full text was obtained to make the final decision. All studies that met the inclusion criteria underwent data extraction. Moreover, the references of the identified papers were screened for additional studies. After title and abstract screening and selection criteria application, 14 clinical studies were included for the qualitative analysis: seven for horizontal/vertical bone augmentation in a simultaneous approach, five for horizontal bone augmentation in a staged approach, and two for vertical bone augmentation in a staged approach. There is scarce literature regarding the added value of APCs in bone augmentation, and most studies had small sample sizes, a lack of standardized protocols, and different outcome variables, which makes comparisons between studies difficult. Out of the 14 studies, four were well-designed randomized clinical trials, where we could find better results for the APCs groups. Most studies, particularly comparative and well-designed studies, demonstrated beneficial and promising results of using APCs in alveolar bone augmentation. However, before high-level evidence-based conclusions can be drawn, more randomized clinical trials must compare the benefits of adding APCs to the gold-standard approach.

Comparison of vertical bone resorption following various types of autologous block bone grafts.

BACKGROUND: This study aims to measure and compare the differences in vertical bone resorption after vertical augmentation using different types of autologous block bone. METHODS: Data were collected from 38 patients who had undergone vertical ridge augmentation using an autologous block bone before implant insertion. The patients were divided into three groups based on the donor sites: ramus bone (RB), chin bone (CB), and iliac crestal bone (IB). RESULTS: The surgical outcome of the augmentation was evaluated at the follow-up periods up to 60 months. In 38 patients, the mean amount of vertical bone gain was 8.36 ± 1.51 mm in the IB group, followed by the RB group (4.17 ± 1.31 mm) and the CB group (3.44 ± 1.08 mm). There is a significant difference in vertical bone resorption between the groups (p < 0.001), and the RB group demonstrated significantly lower resorption than the CB and IB groups (p = 0.011 and p < 0.001, respectively). The most common postoperative complications included neurosensory disturbance in the CB graft and gait disturbance in the IB graft. Out of the 92 implants inserted after augmentation, four implants were lost during the study period, resulting in an implant success rate of 95.65%. CONCLUSIONS: The RB graft might be the most suitable option for vertical augmentation in terms of maintaining postoperative vertical height and reducing morbidity, although the initial gain was greater with the IB graft compared to other block bones.

Interim rehabilitation of an edentulous situation with an overdenture retained by short implants during a staged vertical and horizontal ridge augmentation: a dental technique.

Interim rehabilitation of edentulous patients is essential in implant prosthodontics. However, surgical augmentation may be required for patients with reduced bone density, which complicates the use of an interim prosthesis. This report describes the rehabilitation of an edentulous patient with an interim maxillary overdenture retained by short implants with individual attachments during the healing period of vertical and horizontal ridge augmentation. This technique increased the stability of the interim prosthesis even with shortened flanges to eliminate any pressure on the surgical site. This technique could also be used when immediate loading is not possible due to lack of primary stability of the implants placed for definitive fixed prostheses.

Short Implants versus Longer Implants with Sinus Floor Elevation: A Systemic Review and Meta-Analysis of Randomized Controlled Trials with a Post-Loading Follow-Up Duration of 5 Years.

This study compared the outcome of fixed prostheses supported by short implants (<8 mm) and longer implants (≥8 mm) with an elevated sinus floor after 5 years of follow-up. The literature searches were performed electronically and manually in PubMed, EMBASE, and Web of Science databases to identify relevant articles published from 1 January 2013 to 31 January 2020. We selected eligible studies using inclusion criteria and assessed their quality. From 1688 identified studies, five randomized controlled trials were included. Between the short implant group and the control group, the implant failure-related pooled risk ratio (RR) was 3.64 (p = 0.07). The RR for technical complications was 2.61 (p = 0.0002), favoring longer implants. Marginal peri-implant bone loss after 1 and 5 years of function showed statistically significant less bone loss at short implants (1 year: mean difference = 0.21 mm; p < 0.00001; 5 years: mean difference = 0.26 mm; p = 0.02). The implant failure and the biological failure of both groups were similar after 5 years of follow-up. Short implants could be an alternative to long implants with an elevated sinus floor for atrophic maxillae in aging populations. Studies with larger trials and longer periods of follow-up (10 years) remain essential.

Chemical Properties of Human Dentin Blocks and Vertical Augmentation by Ultrasonically Demineralized Dentin Matrix Blocks on Scratched Skull without Periosteum of Adult-Aged Rats.

Vertical augmentation is one of the most challenging techniques in bone engineering. Several parameters, such mechano-chemical characteristics, are important to optimize vertical bone regeneration using biomaterials. The aims of this study were to chemically characterize human dentin blocks (calcified demineralized dentin matrix: CDM, partially demineralized dentin matrix: PDDM and completely demineralized dentin matrix: CDDM) (2 × 2 × 1 mm3) chemically and evaluate the behavior of PDDM blocks on non-scratched or scratched skulls without periosteum of adult rats (10-12 months old, female) as a vertical augmentation model. The dissolved efficiency of CDM showed 32.3% after ultrasonic demineralization in 1.0 L of 2% HNO3 for 30 min. The 30 min-demineralized dentin was named PDDM. The SEM images of PDDM showed the opening of dentinal tubes, nano-microcracks and the smooth surface. In the collagenase digestion test, the weight-decreasing rates of CDM, PDDM and CDDM were 9.2%, 25.5% and 78.3% at 12 weeks, respectively. CDM inhibited the collagenase digestion, compared with PDDM and CDDM. In the PDDM onlay graft on an ultrasonically scratched skull, the bone marrow-space opening from original bone was found in the bony bridge formation between the human PDDM block and dense skull of adult senior rats at 4 and 8 weeks. On the other hand, in the cases of the marrow-space closing in both non-scratched skulls and scratched skulls, the bony bridge was not formed. The results indicated that the ultrasonic scratching into the compact parietal bone might contribute greatly to the marrow-space opening from skull and the supply of marrow cells, and then bony bridge formation could occur in the vertical augmentation model without a periosteum.

Vertical-guided bone regeneration with a titanium-reinforced d-PTFE membrane utilizing a novel split-thickness flap design: a prospective case series.

OBJECTIVES: To evaluate the feasibility of a newly proposed minimally invasive split-thickness flap design without vertical-releasing incisions for vertical bone regeneration performed in either a simultaneous or staged approach and to analyze the prevalence of adverse events during postoperative healing. MATERIALS AND METHODS: Following preparation of a split-thickness flap and bilaminar elevation of the mucosa and underlying periosteum, the alveolar bone was exposed over the defects, vertical GBR was performed by means of a titanium-reinforced high-density polytetrafluoroethylene membrane combined with particulated autogenous bone (AP) and bovine-derived xenograft (BDX) in 1:1 ratio. At 9 months after reconstructive surgery, vertical and horizontal hard tissue gain was evaluated based on clinical and radiographic examination. RESULTS: Twenty-four vertical alveolar ridge defects in 19 patients were treated with vertical GBR. In case of 6 surgical sites, implant placement was performed at the time of the GBR (simultaneous group); in the remaining 18 surgical, sites implant placement was performed 9 months after the ridge augmentation (staged group). After uneventful healing in 23 cases, hard tissue fill was detected in each site. Direct clinical measurements confirmed vertical and horizontal hard tissue gain averaging 3.2 ± 1.9 mm and 6.5 ± 0.5 mm respectively, in the simultaneous group and 4.5 ± 2.2 mm and 8.7 ± 2.3 mm respectively, in the staged group. Additional radiographic evaluation based on CBCT data sets in the staged group revealed mean vertical and horizontal hard tissue fill of 4.2 ± 2.0 mm and 8.5 ± 2.4 mm. Radiographic volume gain was 1.1 ± 0.4 cm3. CONCLUSION: Vertical GBR consisting of a split-thickness flap and using titanium-reinforced non-resorbable membrane in conjunction with a 1:1 mixture of AP+BDX may lead to a predictable vertical and horizontal hard tissue reconstruction. CLINICAL RELEVANCE: The used split-thickness flap design may represent a valuable approach to increase the success rate of vertical GBR, resulting in predicable hard tissue regeneration, and favorable wound healing with low rate of membrane exposure.

Vertical Ridge Augmentation of Fibula Flap in Mandibular Reconstruction: A Comparison between Vertical Distraction, Double-Barrel Flap and Iliac Crest Graft.

Double-barrel flap, vertical distraction and iliac crest graft are used to reconstruct the vertical height of the fibula. Twenty-four patients with fibula flap were reconstructed comparing these techniques (eight patients in each group) in terms of height of bone, bone resorption, implant success rate and the effects of radiotherapy. The increase in vertical bone with vertical distraction, double-barrel flap and iliac crest was 12.5 ± 0.78 mm, 18.5 ± 0.5 mm, and 17.75 ± 0.6 mm, (p < 0.001). The perimplant bone resorption was 2.31 ± 0.12 mm, 1.23 ± 0.09 mm and 1.43 ± 0.042 mm (p < 0.001), respectively. There were significant differences in vertical bone reconstruction and bone resorption between double-barrel flap and vertical distraction and between iliac crest and vertical distraction (p < 0.001). The study did not show significant differences in implant failure (p = 0.346). Radiotherapy did not affect vertical bone reconstruction (p = 0.125) or bone resorption (p = 0.237) but it showed higher implant failure in radiated patients (p = 0.015). The double-barrel flap and iliac crest graft showed better stability in the height of bone and less bone resorption and higher implant success rates compared with vertical distraction. Radiation therapy did not affect the vertical bone reconstruction but resulted in a higher implant failure.

Short implants versus longer implants in vertically augmented atrophic mandibles: A systematic review of randomised controlled trials with a 5-year post-loading follow-up.

PURPOSE: To compare the clinical outcome of fixed prostheses supported by 4- to 8-mm-long implants with prostheses supported by longer implants placed in vertically augmented atrophic mandibles after a follow-up of 5 years in function. MATERIALS AND METHODS: The Cochrane Central Register of Controlled Trials (CENTRAL) and MEDLINE were searched up to 1st September 2018 for randomised controlled trials (RCTs) with a follow-up of at least 5 years in function comparing fixed prostheses supported by 4- to 8-mm-long implants with prostheses supported by longer implants placed in vertically augmented atrophic mandibles. Outcome measures were prosthesis failure, implant failures, augmentation procedure failures, complications, and peri-implant marginal bone level changes. Screening of eligible studies, assessment of the risk of bias and data extraction were conducted in duplicate and independently by two review authors. The statistical unit of the analysis was the prosthesis. Results were expressed as random-effects models using mean differences for continuous outcomes and risk ratios (RR) for dichotomous outcomes with 95% confidence intervals (CIs). RESULTS: Four eligible RCTs that included originally 135 patients were included. Two RCTs had a parallel-group design and two a split-mouth design. Short implants were 5.0 to 6.6 mm long and were compared with longer implants placed in posterior mandibles augmented with interpositional blocks of bone substitutes. All trials were judged at unclear risk of bias. Twelve (14%) bone augmentation procedures failed to achieve the planned bone height to allow placement of implants with the planned length. Five years after loading, 28 patients (21%) had dropped out from the four RCTs. There were no differences for patients having prosthesis (RR = 1.46; 95% CI: 0.52 to 4.09; P = 0.47; I2 = 0%) or implant (RR = 1.00; 95% CI: 0.31 to 3.21; P = 1.00; I2 = 0%) failures between the two interventions, but there were more patients experiencing complications (RR = 4.72; 95% CI: 2.43 to 9.17; P < 0.00001; I2 = 0%) and peri-implant marginal bone loss (mean difference = 0.60 mm; 95% CI: 0.36 to 0.83; P < 0.00001; I2 = 45%) at longer implants in augmented bone. CONCLUSIONS: Five years after loading, prosthetic and implant failures were similar between the two interventions, but complications and peri-implant marginal bone loss were higher and more severe at longer implants placed in vertically augmented mandibles. Larger trials and longer follow-ups up to 10 years after loading are needed to confirm or reject the present preliminary findings. However in the meantime short implants could be the preferable option.

Posterior atrophic jaws rehabilitated with prostheses supported by 5 × 5 mm implants with a nanostructured calcium-incorporated titanium surface or by longer implants in augmented bone. Five-year results from a randomised controlled trial.

PURPOSE: To evaluate whether 5 × 5 mm dental implants with a novel nanostructured calcium-incorporated titanium surface could be an alternative to implants at least 10-mm long placed in bone augmented with bone substitutes in posterior atrophic jaws. MATERIALS AND METHODS: Forty patients with atrophic posterior (premolar and molar areas) mandibles having 5- to 7-mm bone height above the mandibular canal, and 40 patients with atrophic maxillae having 4- to 6-mm bone height below the maxillary sinus, were randomised according to a parallel-group design to receive one to three 5-mm implants or one to three at least 10-mm long implants in augmented bone at two centres. All implants had a diameter of 5 mm. Mandibles were vertically augmented with interpositional bovine bone blocks covered with resorbable barriers. Implants were placed after 4 months. Maxillary sinuses were augmented with particulated porcine bone via a lateral window covered with resorbable barriers and implants were placed simultaneously. All implants were submerged and loaded after 4 months with provisional prostheses. Four months later, definitive screw-retained or provisionally cemented metal-ceramic or zirconia prostheses were delivered. Patients were followed to 5 years post-loading and the outcome measures were: prosthesis and implant failures, any complication and peri-implant marginal bone level changes. RESULTS: Sixteen patients dropped out before the 5-year evaluation (four short mandibles, three short maxillae, six augmented mandibles and three augmented maxillae). In mandibles, two grafted patients were not prosthetically rehabilitated because of multiple complications, and three implants failed in the same patient (one was a replacement implant) versus one patient who lost his short implant and crown 2 years after loading. In maxillae one short implant failed with its provisional crown 3 months post-loading. There were no statistically significant differences in prostheses (difference in proportion = -0.003; 95% CI: -0.14 to 0.13; P = 1.000) and implant failures (difference in proportion = -0.03; 95% CI: -0.17 to 0.09; P = 0.609) up to 5 years after loading. Significantly more complications occurred at mandibular grafted sites: 17 augmented patients were affected by complications versus nine patients treated with short implants in mandibles (difference in proportion = 0.39; 95% CI: 0.10 to 0.62; P = 0.013). In the maxilla seven sinus-elevated patients versus two patients treated with short implants were affected by complications, the difference not being statistically significant (difference in proportion = 0.25; 95% CI: -0.04 to 0.49; P = 0.128). Patients with mandibular short implants lost on average 1.22 mm of peri-implant bone at 5 years and patients with 10-mm or longer mandibular implants lost 1.70 mm. Patients with maxillary short implants lost on average 1.25 mm of peri-implant bone at 5 years and patients with 10-mm or longer maxillary implants lost 1.73 mm. Longer implants showed a greater bone loss up to 5 years after loading than short implants both in maxillae (mean difference: -0.48 mm; 95% CI: -0.89 to -0.07 mm; P = 0.024) and in mandibles (mean difference: -0.48 mm; 95% CI: -0.79 to -0.18 mm; P = 0.004). CONCLUSIONS: Five years after loading, 5 × 5 mm implants achieved similar results to longer implants placed in augmented bone. Short implants might be a preferable choice to bone augmentation especially in posterior mandibles since the treatment is faster, cheaper and associated with less morbidity; however, 10-year post-loading data are necessary before making reliable recommendations.

Five-year results from a randomised controlled trial comparing prostheses supported by 5-mm long implants or by longer implants in augmented bone in posterior atrophic edentulous jaws.

PURPOSE: To evaluate whether 5-mm short dental implants could be an alternative to augmentation with anorganic bovine bone and placement of at least 10-mm long implants in posterior atrophic jaws. MATERIALS AND METHODS: Fifteen patients with bilateral atrophic mandibles (5 to 7 mm bone height above the mandibular canal) and 15 patients with bilateral atrophic maxillae (4 to 6 mm bone height below the maxillary sinus), and bone thickness of at least 8 mm, were randomised according to a split-mouth design to receive one to three 5-mm short implants or at least 10-mm long implants in augmented bone. Mandibles were vertically augmented with interpositional bone blocks and maxillary sinuses with particulated bone via a lateral window. Implants were placed after 4 months, submerged and loaded, after another 4 months, with provisional prostheses. Four months later, definitive provisionally cemented prostheses were delivered. Outcome measures were: prosthesis and implant failures, any complication and peri-implant marginal bone level changes. RESULTS: In five augmented mandibles the planned 10-mm long implants could not be placed and shorter implants (7.0 and 8.5 mm) had to be used instead. Five years after loading, six patients, five treated in the mandible and one in the maxilla, dropped out. Three prostheses (one mandibular and two maxillary) failed in the short-implant group versus none in the long-implant group. In mandibles one long implant failed versus two short implants in one patient. In maxillae one long implant failed versus three short implants in two patients. There were no statistically significant differences in implant (n = 26; P = 1.00, difference = 3.85%, 95% CI: -12.95% to 20.64%) and prosthetic (n = 26; P = 0.250, difference = 11.54%, 95% CI: -0.74% to 23.82%) failures. Eleven patients had 16 complications at short implants (one patient accounted for six complications) and 12 patients had 14 complications at long implants. There were no statistically significant differences in complications (n = 28; P = 1.00, difference = -3.57%, 95% CI: -30.65% to 23.51%). Five years after loading, patients with mandibular implants lost on average 1.72 mm at short implants and 2.10 mm at long implants of peri-implant marginal bone. This difference was statistically significant (difference = 0.37 ± 0.43 mm; 95% CI: 0.07 to 0.68 mm; P = 0.022). In maxillae, patients lost on average 1.31 mm at short implants and 1.79 mm at long implants. This difference was statistically significant (difference = 0.48 ± 0.43 mm; 95% CI: 0.22 to 0.74 mm; P = 0.002). CONCLUSIONS: Five years after loading, 5-mm short implants achieved similar results to longer implants in augmented bone. The choice of short implants might be preferable to vertical bone augmentation, especially in mandibles, since the treatment is faster and cheaper.

Posterior atrophic jaws rehabilitated with prostheses supported by 6-mm-long 4-mm-wide implants or by longer implants in augmented bone. Five-year post-loading results from a within-person randomised controlled trial.

PURPOSE: To evaluate whether 6-mm-long by 4-mm-wide dental implants could be an alternative to implants at least 10-mm long placed in bone augmented with bone substitutes in posterior atrophic jaws. MATERIALS AND METHODS: A total of 20 patients with bilateral atrophic mandibles and 20 patients with bilateral atrophic maxillae, having 5 to 7 mm of bone height below the maxillary sinus or 6 to 8 mm above the mandibular canal, had their sides of the jaws randomly allocated according to a split-mouth design. They were allocated to receive one to three 6-mm-long and 4-mm-wide implants, or implants at least 10-mm long in augmented bone by two different surgeons in different centres. Mandibles were vertically augmented with interpositional equine bone blocks and resorbable barriers, and implants were placed 3 months later. Maxillary sinuses were augmented with particulated porcine bone via a lateral window and implants were placed simultaneously. All implants were submerged and loaded, after 4 months, with provisional prostheses. Four months later, definitive prostheses were delivered. Outcome measures were prosthesis and implant failures, any complication and radiographic peri-implant marginal bone level changes. The follow-up was 5 years after loading for all patients. RESULTS: Eight patients (five treated in mandibles and three in maxillae) dropped out before the 5-year post-loading follow-up. Four short implants (two maxillary and two mandibular) affected by peri-implantitis failed together with their prostheses versus three mandibular prostheses which could not be placed on implants at least 10-mm long due to graft failures; one was associated with the loss of three implants because of infection. There were no statistically significant differences in implant (P = 1.0) and prosthesis failures (P = 1.0). In total, 19 complications occurred in 14 patients at augmented sites versus five complications in four patients with 6-mm-long implants (P = 0.118). More complications occurred at grafted sites both in mandibles (P = 0.727), and maxillae (P = 0.063), although the differences were not statistically significant. In mandibles, patients with 6-mm-long implants lost an average of 1.34 ± 0.35 mm of peri-implant bone at 5 years versus 2.11 ± 0.59 mm in patients with implants at least 10-mm long. The difference was statistically significant (mean difference = 0.77 ± 0.70 mm; 95% CI: 0.32 to 1.21 mm; P = 0.003). In maxillae, patients with 6-mm-long implants lost an average of 1.52 ± 0.47 mm of peri-implant bone at 5 years versus 1.85 ± 0.51 mm in patients with implants at least 10-mm long. The difference was statistically significant (mean difference = 0.33 ± 0.36 mm; 95% CI: 0.14 to 0.53 mm; P = 0.002). CONCLUSIONS: Results at 5 years after loading indicate that 6-mm-long implants with a conventional diameter of 4 mm achieved similar results to longer implants placed in augmented bone. Short implants might be a preferable choice to bone augmentation, especially in posterior mandibles since the treatment was faster, cheaper and associated with less morbidity. However, 10-year post-loading data are necessary before making reliable recommendations.

Vertical Ridge Gain with Various Bone Augmentation Techniques: A Systematic Review and Meta-Analysis.

PURPOSE: The aim of this systematic review was to determine the most effective alveolar augmentation technique for vertical bone gain. MATERIALS AND METHODS: A systematic search to select clinical trials and retrospective studies done on patients with reduced vertical bone height was conducted. The intervention of interest was autogenous block graft done compared to procedures such as distraction osteogenesis (DO), particulate grafting, block plus particulate grafting with titanium mesh, and tent pole technique in systematically healthy adult patients age 18 and older. The following electronic databases were explored: PubMed, CINAHL, and Dental and Oral Science. A supplementary manual search of published full-text articles from January 2005 to December 2017 was done using Google Scholar. Grey literature was also sought using greylit.org. The review protocol was registered at the Prospero registry (CRD # 42017072432). The risk of bias of the included studies was assessed using EPOC criteria. Meta-analysis was performed using Review Manager for studies with quantitative data on mean values of vertical bone gain and bone resorption achieved with various bone augmentation techniques. Random effect model was used. Heterogeneity among studies was evaluated using the I2 statistic. RESULTS: A total of 2322 articles were found. After excluding the irrelevant papers, only 8 papers were finally selected for the detailed evaluation. Of these 8, 5 were clinical trials, and 3 were retrospective studies. Four studies were on DO, 2 on particulate grafting, 1 on autogenous block grafting plus particulate grafting, and 1 on tent pole grafting. The control group in all studies were autogenous block graft. Meta-analysis revealed no significant difference between DO and autogenous block grafting for vertical bone gain (mean difference 0.82 [-1.28, 2.91]). Similarly, no significant difference was observed in the 2 techniques for bone resorption (mean difference 0.38 [-0.23, 0.99]). CONCLUSIONS: DO was not superior to autogenous block grafting for vertical bone augmentation. Both techniques were associated with a number of complications. There was no difference in the bone resorption observed in the 2 techniques. No conclusive results can be drawn on other techniques on account of limited data.

Anterior maxillary sandwich osteotomy technique with simultaneous implant placement: A novel approach for management of vertical deficiency.

BACKGROUND: The introduction of sandwich osteotomy technique with simultaneous implant placement allowed various procedures to be carried out with a level of great precision and accuracy thus saving time for the patient and clinician. PURPOSE: The aim of the current study is to evaluate the efficacy of this new technique regarding increasing the anterior maxillary alveolar height with simultaneous implant placement. MATERIALS AND METHODS: Nine patients suffering from multiple missing anterior maxillary teeth were selected with vertical dimension not less than 10 mm. anterior maxillary sandwich osteotomy technique was carried out for all patients using xenograft bone particulate with simultaneous implant placement at single stage surgery. RESULTS: For two patients, four implants showed significant marginal bone loss with maximum marginal bone loss up to 2.8 mm. However, the immediate postoperative follow up went uneventful for all nine patients included in the present study. None of them showed any complication regarding postoperative wound dehiscence, infection, or segment mobility. Four months postoperative upon the prosthetic phase, all the 18 placed implant were clinically osseointegtated. CONCLUSION: All 18 implants were successfully integrated in the present study. The prosthetic phase started after 4 months for all cases and there was no need for harvesting of autogenous bone from the patient. But further studies are required to evaluate the viability of such approach in single implant placement cases.

Vertical ridge augmentation using guided bone regeneration procedure and dental pulp derived mesenchymal stem cells with simultaneous dental implant placement: A histologic study in a sheep model.

OBJECTIVES: To determine the effects of bone graft and dental pulp derived mesenchymal stem cells (DPMSCs) implantation with simultaneous dental implant placement on osteointegration, newly formed bone and vertical bone height histologically and histomorphometrically in a sheep model. MATERIAL AND METHODS: A total of 48 implants were divided into three groups. In Group I (n = 16), no material was placed around the implants. In Group II (n = 16), particulate deproteinized bovine bone graft (DBBG) was placed around the implant and in Group III (n = 16), 2 × 106 DPMSCs were placed around the implant with DBBG. All implants were covered with a 20 × 30 mm collagen membrane and the edges of the membrane were fixed with mini screws. The animals were sacrificed 3 and 6 weeks after surgery. Histologic and histomorphometric assessments were performed. RESULTS: The area of newly formed bone in Groups I, II, and III were calculated as percentage 2.15 ± 0.22, 11.88 ± 0.77, and 14.50 ± 0.67 respectively after 3 weeks and 3.33 ± 0.37, 18.45 ± 0.33, and 29 ± 1.07 after 6 weeks, respectively (P < 0.05). Three weeks after dental implant placement, the vertical bone length was 0.17 ± 0.02 mm in Group I, 0.89 ± 0.068 mm in Group II and 0.96 ± 0.05 mm in Group III. After 6 weeks, these values were 0.28 ± 0.03 mm, 1.34 ± 0.08 mm, and 1.49 ± 0.08 mm, respectively. There was no significant difference between Groups II and III at 3 and 6 weeks in terms of vertical bone length. CONCLUSION: Bone graft and DPMSCs application with dental implant have beneficial effects on newly formed bone and vertical bone height in this experimental sheep model.

Short implants versus longer implants in vertically augmented posterior mandibles: result at 8 years after loading from a randomised controlled trial.

PURPOSE: To evaluate whether 6.6-mm long implants could be a suitable alternative to longer implants placed in vertically augmented atrophic posterior mandibles. MATERIALS AND METHODS: Sixty partially edentulous patients having 7 to 8 mm of residual crestal height and at least 5.5-mm thickness measured on computed tomography scans above the mandibular canal were randomly allocated according to a parallel-group design either to receive one to three submerged 6.6-mm long implants or 9.6-mm or longer implants (30 patients per group) placed in vertically augmented bone. Bone was augmented with interpositional anorganic bovine bone blocks fixed with titanium plates and covered with resorbable barriers. Grafts were left to heal for 5 months before implant placement. Four months after implant placement, provisional acrylic prostheses were delivered, replaced, after 4 months, by definitive metal-ceramic prostheses. Outcome measures were: prosthesis and implant failures, complications, and radiographic peri-implant marginal bone level changes. Patients were followed up to 8 years after loading. RESULTS: Eight years after loading 12 patients dropped out, five from the short implant group and seven from the augmented group. The augmentation procedure failed in two patients and only 6.6-mm long implants could be inserted. There were no statistically significant differences for prosthesis and implant failures. Four prostheses failed in three patients of the short implant group versus three prostheses in three patients of the augmented group (Fisher exact test P = 1.000; difference in proportions = 0.01; 95% CI: -0.19 to 0.22). Five short implants failed in three patients versus three long implants in three patients (Fisher exact test P = 1.000; difference in proportions = 0.01; 95% CI: -0.19 to 0.22). There were statistically more complications in augmented patients (27 complications in 22 augmented patients versus 9 complications in 8 patients of the short implant group) (Fisher exact test P < 0.001; difference in proportions = 0.64; 95% CI: 0.38 to 0.79). Both groups gradually lost peri-implant bone in a statistically significant way. Eight years after loading, short implant group patients lost an average of 1.58 mm of peri-implant bone compared with 2.46 mm in the augmented group. Short implants experienced statistically significantly less bone loss (0.88 mm, 95% CI: 0.50 to 1.26 mm) than long implants. CONCLUSIONS: When residual bone height over the mandibular canal is between 7 and 8 mm, 6.6-mm short implants are an interesting alternative to vertical augmentation in posterior atrophic mandibles since the treatment is faster, cheaper and associated with less morbidity.

Individualized Titanium Mesh Combined With Platelet-Rich Fibrin and Deproteinized Bovine Bone: A New Approach for Challenging Augmentation.

Autologous bone transfer is regarded as the gold standard for ridge augmentation before dental implantation, especially in severe bony defects caused by tumor resection or atrophy. In addition to the advantages of autologous bone, transplantation has several disadvantages, such as secondary operation, increased morbidity and pain. The present study reports, for the first time, a combination of a xenogeneic bone substitute (BO) with platelet-rich fibrin (PRF), which is a fully autologous blood concentrate derived from the patient's own peripheral blood by centrifugation. Solid A-PRF+ and liquid i-PRF together with an individualized 3-D planned titanium mesh were used for reconstruction of a severe tumor-related bony defect within the mandible of a former head and neck cancer patient. The BO enriched with regenerative components from PRF allowed the reconstruction of the mandibular resective defect under the 3-D mesh without autologous bone transplantation. Complete rehabilitation and restoration of the patient's oral function were achieved. Histological analysis of extracted bone biopsies confirmed that the new bone within the augmented region originated from the residual bone. Within the limitations of the presented case, the applied concept appears to be a promising approach to increase the regenerative capacity of a bone substitute material, as well as decrease the demand for autologous bone transplantation, even in cases in which autologous bone is considered the golden standard. PRF can be considered a reliable source for increasing the biological capacities of bone substitute materials.

Proof-of-concept study of vertical augmentation using block-type allogenic bone grafts: A preclinical experimental study on rabbit calvaria.

This study aimed to quantify the healing following vertical augmentation of allogenic bone blocks with/without recombinant human bone morphogenetic protein-2 (rhBMP-2) on rabbit calvaria. Experiments were performed using allogenic bone blocks which were grafted bilaterally with or without rhBMP-2 on 20 rabbit calvaria, and these animals were divided to four groups according to the use of rhBMP-2 and healing periods (2 and 8 weeks; n = 10 in each group). Onlay-type bone blocks (8 mm in diameter and 5 mm high) were fixed with a self-tapping screw after removing the cortex in the control group, and the same protocol was applied with the addition of soaking the bone blocks with rhBMP-2 for 15 min in the test group. Radiographic and histologic analyses were performed after 2 or 8 weeks to evaluate the volumetric stability and bone regeneration within the grafted area. The radiographic analysis revealed that the height of the allogenic bone block decreased but its volume was maintained from 2 to 8 weeks in both the control and test groups. The histologic results demonstrated a statistically significant increase in new bone area in the test group, especially in the lower region adjacent to the preexisting calvarial floor. The amount of newly formed bone in all regions of the augmented bone blocks in both the control and test groups was greater at 8 weeks than at 2 weeks. In conclusion, the vertically grafted allogenic bone block maintained its volume with new bone formation, and this was accelerated by the addition of rhBMP-2. These findings indicate that allogenic bone block soaked with rhBMP-2 could be a useful candidate biomaterial for vertical augmentation. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2700-2707, 2018.

Short implants (6mm) vs. vertical bone augmentation and standard-length implants (≥9mm) in atrophic posterior mandibles: a 5-year retrospective study.

This retrospective study compared the 5-year clinical and radiographic outcomes of short implants (6 mm) (short group), and standard-length implants (≥9mm) placed after a vertical augmentation with autologous bone blocks (augmentation group), supporting partial fixed prostheses in the posterior mandible. Forty-five partially edentulous patients were enrolled in the study and evaluated after 5 years: 22 (51 implants) in the augmentation group and 23 (46 implants) in the short group. Eight surgical complications occurred in the augmentation group versus none in the short group (P=0.003). One short implant failed before loading and one standard-length implant failed after 4 years because of peri-implantitis (P=1.0). Eight biological and two prosthetic complications occurred in the augmentation group vs. three biological and three prosthetic complications in the short group (P=0.09 and P=1.0, respectively). A mean marginal bone loss of 1.61±1.12mm in the augmentation group and 0.68±0.68mm in the short group was found (P=0.002). Within the limitations of this study, both techniques resulted in successful clinical results after 5 years, but short implants exhibited less surgical complications and marginal bone loss than standard-length implants placed in augmented bone.

Surgical techniques used in the rehabilitation of partially edentulous patients with atrophic posterior mandibles: A systematic review and meta-analysis of randomized controlled clinical trials.

PURPOSE: Given the lack of general consensus in the literature regarding the best method to rehabilitate partially edentulous patients with extended atrophic edentulous sites in the posterior zone of the mandible, and with a residual ridge height less than 8 mm (with or without bone augmentation procedures), the aim of this systematic review was to analyze all the relevant randomized clinical trials (RCT), and, by means of a meta-analysis of the collected data, draw some conclusions regarding the best available treatments for the rehabilitation of posterior edentulism in partially dentate mandible. MATERIALS AND METHODS: An electronic search was conducted in the MEDLINE and Cochrane Oral Health Group databases for studies published between January 2000 and September 2015 with the use of relevant keywords and hand-searching. All identified publications were screened by the authors according to the Cochrane Data Collection Form for Intervention Reviews. Collected outcomes such as biological complications, vertical ridge changes, implant and prosthetic failure were studied by subgroups analyses. RESULTS: An initial search yielded 81 potential articles, of which 12 studies were chosen for inclusion. Short implants seemed to be effective in limiting incidence of the biological complications (RR: 2.822; 95% CI: 1.809-4.403; p < 0.0001) and degree of ridge height reduction (difference in means of 0.052 mm; 95% CI: 0.026-0.079 mm; p < 0.0001) when compared with long implants placed in augmented bone. Implants placed in augmented areas with the use of onlay block grafts seemed to behave worse than implants placed in the augmented sites regardless of the augmentation procedures. However, this difference did not reach statistical significance. CONCLUSION: Findings from subgroup analyses revealed that (1) short implants placed in the posterior atrophic areas of partially edentulous mandibles were associated with superior outcomes compared with long implants in augmented bone, such as lower rate of biological complications and of peri-implant bone loss; whereas (2), there was no evidence that onlay augmentation was inferior to any of the other augmentation techniques employed.

Clinical efficacy of grafting materials in alveolar ridge augmentation: A systematic review.

PURPOSE: To evaluate the efficacy of grafting materials in lateral and vertical ridge augmentations. MATERIALS AND METHODS: A systematic review of the literature on the clinical use of grafting materials of the years 1995 to April 2015 was conducted using electronic search of PubMed and Cochrane libraries and hand search of eight print journals. A total of 184 papers were included, comprising 6182 patients. Parameters evaluated were observation period [months], bone formation [histologic area%], defect fill [%], horizontal and vertical gain [mm], loss of augmented volume [mm], complication rate [%], and implant survival rate [%]. Results are expressed as weighted means ± SD. RESULTS: Results were obtained after a weighted mean observation period of 27.4 months (range 3-168 months). Bone formation in the augmented areas varied from 33.2 ± 14.9% for allogeneic grafts to 56.0 ± 25.6% for mixtures of autogenous and other grafting materials. Defect fill in dehiscence defects ranged from 51.0 ± 13.6% (synthetic) to 85.8 ± 13.4% (xenogeneic) for the different materials, with an overall weighted mean of 79.8 ± 18.7%. Weighted mean horizontal gain for all particulate grafting materials was 3.7 ± 1.2 mm, with variation between 2.2 ± 1.2 mm (synthetic) and 4.5 ± 1.0 mm (mixtures of autogenous bone with allogeneic/xenogeneic grafting material) without statistical significance. Weighted overall mean vertical gain was 3.7 ± 1.4 mm. Vertical gain was substantially higher when space-making barrier materials such as titanium meshes were used; however this was also associated with strong increase in complication rate. Block grafts achieved higher horizontal gain by approximately 1 mm. The use of block grafts achieved significantly increased vertical gain compared to particulate material only when autogenous block grafts from extraoral donor sites were used. CONCLUSION: Horizontal and vertical gain by 3.7 mm on average can be achieved using particulate materials. This can be increased by using titanium meshes. Substantial vertical gains beyond this dimension require the use of extraoral bone block grafts.