Indications for implant-supported rehabilitation of the posterior atrophic maxilla: A multidisciplinary consensus among experts in the field utilising the modified Delphi method.

PURPOSE: To establish consensus-driven guidelines that could support the clinical decision-making process for implant-supported rehabilitation of the posterior atrophic maxilla and ultimately improve long-term treatment outcomes and patient satisfaction. MATERIALS AND METHODS: A total of 33 participants were enrolled (18 active members of the Italian Academy of Osseointegration and 15 international experts). Based on the available evidence, the development group discussed and proposed an initial list of 20 statements, which were later evalu-ated by all participants. After the forms were completed, the responses were sent for blinded ana-lysis. In most cases, when a consensus was not reached, the statements were rephrased and sent to the participants for another round of evaluation. Three rounds were planned. RESULTS: After the first round of voting, participants came close to reaching a consensus on six statements, but no consensus was achieved for the other fourteen. Following this, nineteen statements were rephrased and sent to participants again for the second round of voting, after which a consensus was reached for six statements and almost reached for three statements, but no consensus was achieved for the other ten. All 13 statements upon which no consensus was reached were rephrased and included in the third round. After this round, a consensus was achieved for an additional nine statements and almost achieved for three statements, but no consensus was reached for the remaining statement. CONCLUSION: This Delphi consensus highlights the importance of accurate preoperative planning, taking into consideration the maxillomandibular relationship to meet the functional and aesthetic requirements of the final restoration. Emphasis is placed on the role played by the sinus bony walls and floor in providing essential elements for bone formation, and on evaluation of bucco-palatal sinus width for choosing between lateral and transcrestal sinus floor elevation. Tilted and trans-sinus implants are considered viable options, whereas caution is advised when placing pterygoid implants. Zygomatic implants are seen as a potential option in specific cases, such as for completely edentulous elderly or oncological patients, for whom conventional alternatives are unsuitable.

Dense Polytetrafluoroethylene Membrane versus Titanium Mesh in Vertical Ridge Augmentation: Clinical and Histological Results of a Split-mouth Prospective Study.

AIM AND OBJECTIVE: The aim of the present split-mouth prospective study was to evaluate clinically and histologically the bone regeneration obtained following preprosthetic vertical bone augmentation performed with titanium-reinforced dense polytetrafluoroethylene membrane (d-PM) compared to titanium mesh (TM). MATERIALS AND METHODS: Healthy adult patients presenting with bilateral partial edentulism in the posterior mandible requiring vertical ridge augmentation for implant placement purposes were consecutively included. One side of the mandible was randomly assigned to the use of d-PM, the other to TM. The graft consisted in a mixture of autogenous bone harvested nearby the surgical site and deproteinized bovine bone mineral particles in a 1:1 ratio. On each side during bone augmentation surgery, a 2-mm diameter mini-implant was inserted for clinical and histological analyses. After a healing period of 8 months, the second surgical phase was carried out to remove the nonresorbable barriers, to evaluate clinically the vertical bone gain, and to collect a bone biopsy that included the mini-implant. During the same surgical session, dental implants were inserted in a prosthetically guided position. RESULTS: A total of five patients were enrolled. Eight out of 10 sites healed uneventfully. In the remaining two sites, premature exposure of the TM was observed. Mean vertical bone gain of 4.2 and 1.5 mm was achieved in d-PM and TM groups, respectively (p = 0.06). A mean mineralized tissue of 48.28 and 35.54% was observed in d-PM and TM groups, respectively (p = 0.51). CONCLUSION: The vertical bone gain, although not significantly, was higher in the d-PM group. Similar histological outcomes were noticed if exposure did not occur. In case of wound dehiscence, major resorption was observed. CLINICAL SIGNIFICANCE: Both d-PM and TM can be used to augment atrophic localized ridges vertically. The outcome of bone regeneration seems to be impaired by exposure of the device. How to cite this article: Maiorana C, Fontana F, Rasia dal Polo M, et al. Dense Polytetrafluoroethylene Membrane versus Titanium Mesh in Vertical Ridge Augmentation: Clinical and Histological Results of a Split-mouth Prospective Study. J Contemp Dent Pract 2021;22(5):465-472.

Aesthetic outcomes of non-functional immediately restored single post-extraction implants with and without connective tissue graft: A multicentre randomized controlled trial.

OBJECTIVES: To compare the 1-year aesthetic results of flapless single implants, placed in fresh extraction sockets with bone replacement and immediate provisional restoration with or without a connective tissue graft (CTG). MATERIAL AND METHODS: The present study proposes a partially blinded multicentre parallel randomized controlled trial, where computer-generated tables were used for central randomization to allocate treatments. A total of 59 of the 60 patients screened by eight private practices in Northern Italy fulfilled the inclusion criteria. Immediate implants were placed in a fresh extraction socket with a non-functional immediate provisional restoration with (Test group) or without (Control group) a CTG. The primary outcome variable was the implant Crown Aesthetic Index (ICAI) at the 1-year follow-up. RESULTS: ICAI for the 59 randomized patients (Test group = 31, Control group = 28) at the 1-year follow-up was 4.69 (95% CI = 3.16-6.22) for the Test group and 3.45 (95% CI = 1.83-5.08) for the Control group, without statistically significant difference between the two groups (p = .086). One implant failure was recorded in each group, resulting in an implant survival rate of 96.8% [95% CI = 83.3-99.9] for the Test group and 96.4% [95% CI = 81.7-99.9] for the Control group. Other secondary outcome variables and complication rates were comparable across the two groups. CONCLUSIONS: Within the limitations of the present clinical trial, the results suggested that the adjunct use of CTG is not mandatory to achieve successful aesthetic outcomes for a well-planned immediate implant placement with immediate non-functional provisional restoration in a fresh extraction socket.

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.

Osseointegrated implants in vertical ridge augmentation with a nonresorbable membrane: a retrospective study of 75 implants with 1 to 6 years of follow-up.

The aim of this study was to retrospectively evaluate 75 implants inserted in vertically augmented bone at the time of or prior to implant placement after 1 to 6 years of prosthetic loading. The study included 21 patients (29 surgical sites). The vertical procedure was performed combining a titanium-reinforced expanded polytetrafluoroethylene membrane with autograft (7 sites), allograft (5 sites), or auto-xenograft (17 sites). Healing was uneventful in 24 surgical sites. Three sites showed premature exposure, and two sites presented an abscess. Two implants were lost, for a cumulative survival rate of 93.6%. Mean bone remodeling at 1, 2, 3, 4, 5, and 6 years was 0.34, 0.72, 1.04, 0.84, 0.56, and 0.61 mm, respectively. The implant success rate was higher with a simultaneous approach (82.5%) compared with a staged approach (66.8%). Implants surrounded by keratinized mucosa revealed a higher success rate (82.1%) than those without it (58.4%).

Twelve-Year Retrospective Follow-Up of Machined Implants in the Posterior Maxilla: Radiographic and Peri-Implant Outcome.

PURPOSE: To retrospectively evaluate the survival rate of machined implants in sinus-lifted posterior maxilla after 12 years, with special reference to radiographic outcome and peri-implantitis. MATERIALS AND METHODS: From 37 possible candidates, 29 patients with 59 implants were evaluated. Implants were placed in the posterior maxilla in combination with a sinus elevation procedure (27 patients) or 6 months after sinus elevation (2 patients). Marginal bone level changes were radiographically evaluated at baseline and 1, 7, and 12 years post-loading. Probing depth was measured; presence/absence of plaque and bleeding on probing were recorded. RESULTS: Four out of 59 implants failed in 4 out of 29 patients (cumulative survival rate = 93.2%). The mean bone loss was 0.78 mm (± 0.88) after 12 years. Changes in the mean bone level were statistically significant between baseline and all the other follow-up intervals (p < .001). Statistically significant differences could be demonstrated for the first- to 12th-year interval (p < .05) and for the seventh- to 12th-year interval (p < 0.001). No statistically significant differences could be demonstrated at the first- to seventh-year interval (p = .32). The mean overall probing depth was 2.9 ± 0.66 mm. Probing depth was moderately correlated with the marginal bone changes at 7 year and after 12 year follow up (p = .05). No signs of peri-implantitis were reported during the 12-year follow-up period. CONCLUSIONS: This follow-up demonstrates a very good prognosis when implants with machined surfaces are used. The frequencies of implant failures were very small. Within the limits of the results from this study, the risk of peri-implantitis in the posterior maxilla might be considered a minor problem when implants with machined surfaces are used.

Evaluation of a resorbable collagen matrix infused with rhPDGF-BB in peri-implant soft tissue augmentation: a preliminary report with 3.5 years of observation.

Soft tissue augmentation around dental implants in the esthetic region remains a challenging and unpredictable procedure. The ideal surgical technique would include of an off-the-shelf product to minimize morbidity after autogenous grafting procedures. The aim of this study was to use a resorbable collagen matrix (Mucograft) to serve as a scaffold to recombinant human platelet-derived growth factor BB (rhPDGF-BB) to increase peri-implant soft tissue volume in anterior maxillary sites. A total of six patients who had previously undergone a bone regeneration procedure were included in this study. The collagen matrix was applied during stage-two surgery (expanded polytetrafluoroethylene membrane removal and implant placement). Measurements were performed through customized stents by means of endodontic files, and at abutment connection, a soft tissue biopsy specimen was harvested for histologic examination. The healing period was uneventful in all six patients. Measurements were taken apically, centrally, and occlusally for each site. The mean gains in volume from baseline to the 4-month measurement at the apical, central, and occlusal aspects were 0.87 ± 2.13 mm, 2.14 ± 3.27 mm, and 0.35 ± 3.20 mm, respectively. The results showed a moderate increase in the soft tissue volume in esthetic peri-implant sites when applying a collagen matrix infused with rhPDGF-BB. However, the measuring techniques available need to be further improved to record exact changes in the soft tissue volume.

Clinical classification of complications in guided bone regeneration procedures by means of a nonresorbable membrane.

The goal of classifying complications in guided bone regeneration procedures with nonresorbable membranes is to provide the clinician with an instrument for easier identification of both the problem and treatment modality. A standardized terminology represents a key point for proper communication among clinicians and provides guidelines for managing these drawbacks.

Effects of a calcium phosphate coating on the osseointegration of endosseous implants in a rabbit model.

OBJECTIVES: The aim of the present study was to evaluate a Ca-P coated implant surface in a rabbit model. The Ca-P surface (test) was compared to the titanium porous oxide surface (control) in terms of bone-to-implant contact (BIC) and removal torque value. MATERIALS AND METHODS: Two hundred and sixteen dental implants were inserted in the tibia and in the femur of 36 rabbits. One hundred and eight were represented by Ca-P oxidized surface implant and other 108 were titanium porous oxide surface modified implants. Each rabbit received six implants. Animals were sacrificed after 2, 4 and 9 weeks of healing. Each group included 12 rabbits. The femoral implant and the proximal implant of the tibia of each animal were subjected to the histologic analysis and the distal implants of the tibia underwent removal torque test (RTQ). RESULTS: Histological analysis in terms of BIC and RTQ did not revealed any significant difference between the Ca-P oxidized surface and the oxidized surface at 2 and 4 weeks. At 9 weeks, the oxidized surface demonstrated better results in terms of RTQ in the tibia. CONCLUSION: In conclusion, findings from the present study suggested that the Ca-P coating had no beneficial effect in improving bonding strength at the bone-implant interface either at 2, 4 and 9 weeks.

Surface-modified zirconia implants: tissue response in rabbits.

AIM: To evaluate the bone tissue response to zirconia implants with three different surface modifications in comparison with the oxidized titanium surface with the goal to optimize osseointegration in terms of strength and speed. MATERIALS AND METHODS: A total of 18 rabbits with 143 implants were used. One hundred and twenty-three were threaded zirconia ceramic implants with three different surface topographies and 20 modified titanium oxide implants were controls. Each rabbit received eight implants and sacrificed after 3 weeks. The removal torque test (RTQ) and histology were performed. RESULTS: Sixteen out of 18 rabbits completed the study with a total of 110 implants. No statistical significance was observed between the chemical modification implants compared with the topographically modified zirconia implant in terms of interfacial shear strength proven by the RTQ applied. No statistical significance was also observed in the bone-to-implant contact between the zirconia implants and the control oxidized implants. CONCLUSIONS: The findings suggest that additional specific chemical modifications of the topographically modified zirconia implants do not seem to enhance the bone-to-implant contact and appear not to increase the interfacial shear strength.

Vertical ridge augmentation using an equine block infused with recombinant human platelet-derived growth factor-BB: a histologic study in a canine model.

This preclinical study evaluated the efficacy of purified recombinant human platelet-derived growth factor (rhPDGF-BB), combined with a novel equine hydroxyapatite and collagen (eHAC) bone block, in providing vertical bone regeneration in critical-size defects simulating localized mandibular alveolar bone atrophy. In addition, the impact of barrier membrane placement in growth factor-mediated bone regeneration was also studied. Bilateral posterior mandibular defects simulating severe localized bony atrophy were created in 12 adult foxhounds following removal of all four mandibular premolars. Three months later, the defects were grafted as follows: group A: eHAC block alone; group B: eHAC block + collagen membrane; group C: eHAC block + rhPDGF-BB; group D: eHAC block + rhPDGF-BB + membrane. The animals were sacrificed after 5 months and the grafted areas were examined histologically, radiographically, and clinically. Groups A and B (controls) exhibited little to no vertical bone regeneration. Group C demonstrated significant vertical bone regeneration, with dense, well-vascularized bone, high bone-to-implant contact, and accelerated replacement of graft particles with newly formed bone. In group D, with the imposition of a barrier membrane, robust bone regeneration was less evident when compared to group C. As in the first study in this series, the importance of the periosteum as a source of osteoprogenitor cells in growth factor-mediated regenerative procedures is examined.

Clinical outcomes of vertical bone augmentation to enable dental implant placement: a systematic review.

BACKGROUND: This review addressed the focused question of what is the predictability of vertical ridge augmentation techniques for patients, who were diagnosed with insufficient alveolar bone volume for the placement of dental implants. MATERIAL AND METHODS: A systematic online review of three main databases was performed between 1966 and 1 November 2007. Four groups of vertical bone augmentation techniques have been identified and evaluated: (1) guided bone regeneration, (2) distraction osteogenesis, (3) onlay bone grafting, and (4) an array of different techniques. Data extraction was based on the following outcomes: (a) success and failure rate of the procedure (vertical bone gain/loss), (b) complication rate of the procedure, and (c) implant survival, success and failure rate. RESULTS: The initial search identified 189 papers from the electronic database. The review produced seven papers for GBR, 13 reporting distraction osteogenesis, five for onlay bone grafting and three describing different techniques. CONCLUSIONS: For the concept of vertical ridge augmentation to enable dental implant placement, there are clinical and histological data supporting its potential use. Given the confined number of investigators using these techniques and the low number of patient treatments reported in the literature, the generalizability of this approach is limited at this time.

Clinical and histologic evaluation of allogeneic bone matrix versus autogenous bone chips associated with titanium-reinforced e-PTFE membrane for vertical ridge augmentation: a prospective pilot study.

PURPOSE: To compare clinically and histologically an allogeneic bone matrix to autogenous bone chips in the vertical ridge augmentation technique using titanium-reinforced e-PTFE membranes. MATERIALS AND METHODS: The study protocol was designed to include patients with bilateral posterior mandibular partial edentulism. Patients were treated with a split-mouth design approach: each side was randomly assigned to the test group (titanium-reinforced e-PTFE membrane and allogeneic bone matrix) or to the control group (titanium-reinforced e-PTFE membrane and autogenous bone chips). Different clinical parameters including the amount of vertically regenerated bone (DSB) and biologic complications were recorded. Histomorphometric analysis and the bone-implant contact percentage were performed. RESULTS: Five female patients were enrolled in the study. Ten edentulous sites were vertically augmented and 25 implants were inserted (13 test group, 12 control group) with a staged approach. In the test group no membrane was exposed. The mean bone regeneration was 4.70 mm (SD 0.48 mm). All 13 implants appeared clinically stable. In the control group, 1 membrane was exposed after 2 months. The mean crestal bone regeneration was 4.10 mm (SD 0.88 mm). All 12 implants were stable at the abutment connection. Nine biopsy specimens from the regenerated areas were evaluated. Vertical bone regeneration was evident in both groups since all the samples demonstrated trabecular bone with different degrees of maturation and mineralization in the regenerated area. CONCLUSION: Within the limits of this study based on 5 patients, it appears that the behavior of the allogeneic bone matrix is similar to that of autogenous bone chips when used for vertical ridge augmentation by means of guided bone regeneration techniques. Both grafts demonstrated analogous histologic characteristics. Nevertheless, long-term clinical studies are needed to confirm these preliminary results.

Biocompatibility and manageability of a new fixable bone graft for the treatment of localized bone defects: preliminary study in a dog model.

The present investigation was performed to compare the biocompatibility, safety, and manageability of a newly developed bone block and a deproteinized bovine bone block (Bio-Oss) for the treatment of localized bone defects in a dog model. Two male beagle dogs were used for this study. The mandibular premolars were extracted and two saddle-type defects were created bilaterally in the edentulous area. The defects were filled according to a randomized design with Bio-Oss bone block or with an equine hydroxyapatite plus collagen bone block (eHAC). Most control and test sites developed dehiscences during healing. After 4 weeks, the animals were euthanized and each hemimandible was prepared for histologic examination. No significant difference in terms of local tolerance was observed between test and control sites, and test and control sites showed similar histologic findings. However, a significant difference was noticed between the Bio-Oss block and the new bone block in terms of manageability.

Vertical ridge augmentation by expanded-polytetrafluoroethylene membrane and a combination of intraoral autogenous bone graft and deproteinized anorganic bovine bone (Bio Oss).

OBJECTIVE: To evaluate, from a histological and histomorphometrical perspective, the efficacy of a 1 : 1 mixture of deproteinized bovine bone mineral (DBBM) and autogenous bone graft associated with an expanded-polytetrafluoroethylene (e-PTFE) membrane for vertical ridge augmentation in the human. MATERIAL AND METHODS: Seven patients with 10 surgical sites requiring vertical ridge augmentation of partially edentulous lower jaws were included in the study. The vertical augmentation procedure was performed combining a titanium-reinforced e-PTFE Gore-Tex membrane with a composite graft consisting of a 1 : 1 ratio of DBBM (Bio-Oss) and autogenous bone. Twenty-seven Branemark implants have been inserted. Eleven biopsies from the regenerated area were analyzed histologically and histomorphometrically. RESULTS: The healing period was uneventful in nine surgical sites. In one site the membrane showed an exposure after 3 months. At the abutment connection, all implants appeared stable and submerged by a hard regenerated tissue clinically similar to bone. The histological analysis showed new bone formation and ongoing remodelling of the autogenous bone and the DBBM particles. CONCLUSIONS: The findings from the present clinical and histological study support the use of a 1 : 1 combination of DBBM and autogenous bone chips for vertical ridge augmentation by means of guided bone regeneration techniques. The regenerated bone may lead to proper osseointegration of a dental implant inserted at the time of the regenerative procedure or after a healing period of at least 6 months. DBBM undergoes very slow resorption and substitution with new bone. Furthermore, long-term clinical studies are needed to confirm the positive effect of DBBM in enhancing the lasting stability of the vertically augmented bone.

Histological evaluation, in rabbit tibiae, of osseointegration of mini-implants in sites prepared with Er:YAG laser versus sites prepared with traditional burs.

OBJECTIVE: The aim of this study was to evaluate the different bone reactions in rabbit tibiae after the insertion of mini-implants by using two different techniques of site preparation: the superpulsed Er:YAG laser (VPS system) versus the traditional technique with burs. METHODS: One mm wide and 2 mm long implant sites were made in the tibiae of 12 rabbits (8 for each tibia): the authors used an Er:YAG laser with a sapphire tip on a contra-angle hand piece with a 1.0 mm diameter in a VPS mode (with 200 mJ and 30 Hz) to make 4 bone sites and a calibrated traditional bur to drill the other 4 sites in each tibia. The authors inserted a threaded mini-implant, with a sandblasted and acid-etched surface, in the 2 laser implant sites and in the 2 drilled sites of each tibia. The other sites were used as controls. At 0, 7, 15, 30, 45, and 60 days from the surgery, 2 animals each were euthanized, and the retrieved specimens were evaluated. RESULTS: No implant was lost, and the osseointegration was comparable in all implant sites. Histologically, in the 7- and 15-day postoperative specimens, the laser sites showed some amorphous tissue caused by the carbonization of bone during the laser procedure. The sites without implants showed good regeneration of the bone: it was faster in the drill defects because in the laser ones there was some carbonized amorphous tissue. After 30 days postoperatively, the regeneration was the same in all sites. CONCLUSIONS: In comparison with the traditional drilling procedures, Er:YAG laser can be considered efficient in surgery of the bone without inducing irreversible damages, even if it is possible to observe the presence of some carbonized amorphous tissue in the early part of the healing process. This tissue is progressively resorbed in a way similar to a bone graft and doesn't impede the bone formation and osseointegration processes. Further clinical and histological studies are necessary to better define this amorphous tissue and an efficient and safe operative protocol in the surgery of bone with an Er:YAG laser.

Long-term evaluation of osseointegrated implants placed in sites augmented with sinus floor elevation associated with vertical ridge augmentation: a retrospective study of 38 consecutive implants with 1- to 7-year follow-up.

This clinical study retrospectively evaluated, after 1 to 7 years of prosthetic loading, 38 implants consecutively placed in 16 surgical sites, where severe atrophy of the posterior maxilla was treated by combining sinus elevation with the vertical ridge regenerative procedure. Two different surgical techniques were adopted. In seven patients (16 implants), implants were placed at the same stage as the regenerative procedures. In the other seven patients (22 implants), implant placement was performed at second-stage surgery, after 6 to 13 months of submerged membrane healing. Each implant was classified as a success, survival, or failure. The distance between the top of the implant shoulder and the first visible bone-implant contact was assessed radiographically for every implant at the mesial and distal sides. Two membranes became exposed during the healing process (12.5%). In the remaining 14 sites (87.5%), the membrane remained covered for a 6- to 13-month healing period. The survival rate of the implants was 92.1%, whereas the success rate was 76.3%. Three implants (7.9%) failed. A comparison of the implant shoulder-bone-implant contact distances between abutment connection and the last examination showed a mean crestal loss of 1.65 mm at the mesial side and 1.68 mm at the distal side. The bone regenerated vertically by means of sinus floor elevation and vertical ridge augmentation showed the same biologic behavior as native, nonregenerated bone; however, in a few cases, its remodeling pattern seemed to determine slightly higher bone crest resorption.