Accuracy of semi-occlusive CAD/CAM titanium mesh using the reverse guided bone regeneration digital protocol: A preliminary clinical study.

PURPOSE: The reverse guided bone regeneration protocol is a digital workflow that has been introduced to reduce the complexity of guided bone regeneration and promote prosthetically guided bone reconstruction with a view to achieving optimal implant placement and prosthetic finalisation. The aim of the present study was to investigate the accuracy of this digital protocol. MATERIALS AND METHODS: Sixteen patients with partial edentulism in the maxilla or mandible and with vertical or horizontal bone defects were treated using the reverse guided bone regeneration protocol to achieve fixed implant rehabilitations. For each patient, a digital wax-up of the future rehabilitation was created and implant planning was carried out, then the necessary bone reconstruction was simulated virtually and the CAD/CAM titanium mesh was designed and used to perform guided bone regeneration. The computed tomography datasets from before and after guided bone regeneration were converted into 3D models and aligned digitally. The actual position of the mesh was compared to the virtual position to assess the accuracy of the digital project. Surgical and healing complications were also recorded. A descriptive analysis was conducted and a one-sample t test and Wilcoxon test were utilised to assess the statistical significance of the accuracy. The level of significance was set at 0.05. RESULTS: A total of 16 patients with 16 treated sites were enrolled. Comparing the virtually planned mesh position with the actual position, an overall mean discrepancy between the two of 0.487 ± 0.218 mm was achieved. No statistically significant difference was observed when comparing this to a predefined minimum tolerance (P = 0.06). No surgical complications occurred, but two healing complications were recorded (12.5%). CONCLUSION: Within the limitations of the present study, the reverse guided bone regeneration digital protocol seems to be able to achieve good accuracy in reproducing the content of the virtual plan. Nevertheless, further clinical comparative studies are required to confirm these results.

Semi-occlusive CAD/CAM titanium mesh for guided bone regeneration: Preliminary clinical and histological results.

PURPOSE: Guided bone regeneration is a widely used technique for the treatment of atrophic arches. A broad range of devices have been employed to achieve bone regeneration. The present study aimed to investigate the clinical and histological findings for a new titanium CAD/CAM device for guided bone regeneration, namely semi-occlusive titanium mesh. MATERIALS AND METHODS: Nine partially edentulous patients with vertical and/or horizontal bone defects underwent a guided bone regeneration procedure to enable implant placement. The device used as a barrier was a semi-occlusive CAD/CAM titanium mesh with a laser sintered microperforated scaffold with a pore size of 0.3 mm, grafted with autogenous and xenogeneic bone in a ratio of 80:20. Eight months after guided bone regeneration, surgical and healing complications were evaluated and histological analyses of the regenerated bone were performed. RESULTS: A total of 9 patients with 11 treated sites were enrolled. Two healing complications were recorded: one late exposure of the device and one early infection (18.18%). At 8 months, well-structured new regenerated trabecular bone with marrow spaces was mostly present. The percentage of newly formed bone was 30.37% ± 4.64%, that of marrow spaces was 56.43% ± 4.62%, that of residual xenogeneic material was 12.16% ± 0.49% and that of residual autogenous bone chips was 1.02% ± 0.14%. CONCLUSION: Within the limitations of the present study, the results show that semi-occlusive titanium mesh could be used for vertical and horizontal ridge augmentation. Nevertheless, further follow-ups and clinical and histological studies are required.

What is the Incidence of Late Complications Associated With Lower Third Molar Coronectomy? 10-Year Follow-Up Results.

PURPOSE: Coronectomy is an operation to manage impacted third molars (M3s) considered at high risk for mandibular nerve injury but long-term outcomes are still lacking. The purpose of this study was to estimate the risk of late complications occurring within 10 years following lower M3 coronectomy. METHODS: The investigators designed a prospective cohort study and enrolled a sample of 94 patients treated with coronectomy of third mandibular molars at the Unit of Oral and Maxillofacial Surgery of the University of Bologna, from 2009 to 2012. This follow-up study included all of the patients from the original study who completed 10 years of follow-up. The primary outcome variables is postoperative late complication occurring between 5 and 10 years after coronectomy coded as present or absent. Late complications were defined as root exposure, nerve injury, pulpitis, periapical infection, and reoperation. The secondary outcome variable was probing pocket depth. Covariates examined were age, smoking and type of M3 impaction. Descriptive statistical analyses were performed. RESULTS: The inception cohort was composed of 94 subjects who had 116 coronectomies (k) completed. The study cohort was composed of subjects with 10 years of follow-up and included 48 subjects (k = 60) with a mean age of 28.99 ± 8.9 years. Between years 5 and 10 of follow-up, 2 subjects (4%) have complications; all root exposures diagnosed at years 8 or 9 after surgery. In another case root removal was required for orthodontics reason. No case of nerve injury to the inferior alveolar nerve occurred, and no periapical infection was observed around the residual roots. The mean 10-year probing pocket depth was 3.31 ± 0.92 mm (1,66-5,66 mm). There were too few complications to identify risk factors for late complications. CONCLUSIONS: Within all the limitations of this study, the results of this prospective study imply that coronectomy is a useful surgical technique for the treatment of M3s at high neurological risk, to avoid nerve injury to the inferior alveolar nerve. In addition, after coronectomy, retained roots did not develop late infection or periapical infection in the long term. However, in a few cases, removal of retained roots was required at 10 years, due to root migration in the oral cavity. The risk for late complications is uncommon, but persistent.

Vertical and horizontal ridge augmentation using customized CAD/CAM titanium mesh with versus without resorbable membranes. A randomized clinical trial.

OBJECTIVES: The aim was to evaluate the role of resorbable membranes applied over customized titanium meshes related to soft tissue healing and bone regeneration after vertical/horizontal bone augmentation. MATERIALS AND METHODS: Thirty patients with partial edentulism of the maxilla/mandible, with vertical/horizontal reabsorption of the alveolar bone, and needing implant-supported restorations, were randomly divided into two groups: Group A was treated using only custom-made meshes (Mesh-) and Group B using custom-made meshes with cross-linked collagen membranes (Mesh+). Data collection included surgical/technical and healing complications, "pseudo-periosteum" thickness, bone density, planned bone volume (PBV), regenerated bone volume (RBV), regeneration rate (RR), vertical bone gain (VBG), and implant survival in regenerated areas. Statistical analysis was performed between the two study groups using a significance level of α = .05. RESULTS: Regarding the healing complications, the noninferiority analysis proved to be inconclusive, despite the better results of group Mesh+ (13%) compared to group Mesh- (33%): estimated value -1.13 CI-95% from -0.44 to 0.17. Superiority approach confirmed the absence of significant differences (p = .39). RBV was 803.27 mm3 and 843.13 mm3 , respectively, and higher RR was observed in group Mesh+ (82.3%) compared to Mesh- (74.3%), although this value did not reach a statistical significance (p = .44). All 30 patients completed the study, receiving 71 implants; 68 out of them were clinically stable and in function. CONCLUSION: The results showed that customized meshes alone do not appear to be inferior to customized meshes covered by cross-linked collagen membranes in terms of healing complication rates and regeneration rates, although superior results were observed in group Mesh+compared to group Mesh- for all variables.

A microcomputed tomography analysis of bone tissue after vertical ridge augmentation with non-resorbable membranes versus resorbable membranes and titanium mesh in humans.

PURPOSE: Guided bone regeneration is a frequently used surgical procedure for hard tissue reconstruction when horizontal and or/vertical augmentation are needed. The treatment concept is based on the application of occlusive membranes like non-resorbable membranes or titanium mesh plus resorbable membranes. However, there are no studies comparing the microcomputed tomography results for bone obtained using these two procedures, and this was the purpose of the present study. MATERIALS AND METHODS: A total of 40 patients with vertical posterior bone mandibular atrophy were randomly assigned to group A (guided bone regeneration with titanium-reinforced polytetrafluoroethylene membrane and simultaneous implant placement) or group B (guided bone regeneration with titanium mesh and collagen membrane and simultaneous implant placement). Tissue biopsy specimens were obtained from augmented sites after 9 months for microcomputed tomography analysis of volume of interest. Bone volume (BV/TV), biomaterial volume (MatV/TV), soft tissue volume (StV/TV), trabecular thickness (TbTh), trabecular number (TbN) and trabecular separation (TbSp) were measured. The correlation between regenerated bone and native bone was also evaluated. STATA software (StataCorp, College Station, TX, USA) was utilised for statistical analysis (significance α = 0.05). RESULTS: In group A, the values of BV/TV, MatV/TV and StV/TV in regenerated bone were 28.8%, 8.9% and 62.4%, respectively. In group B, the values of BV/TV, MatV/TV and StV/TV were 30.0%, 11.0% and 59.0%, respectively. No statistical differences were found between the two groups for any of the variables (P < 0.05). In both groups, considerable differences were noted between regenerated and native bone (P > 0.05), with a slight correlation between the microcomputed tomography parameters that suggests that native bone influences the quality of regenerated bone. CONCLUSIONS: Based on microcomputed tomography analysis, both surgical approaches facilitated the obtention of approximately 30% of newly formed bone with the same microarchitecture. Native bone influences the quality and microarchitecture of the obtained bone, irrespective of the technique used.

Vertical ridge augmentation (VRA) with Ti-reinforced d-PTFE membranes or Ti meshes and collagen membranes: 1-year results of a randomized clinical trial.

OBJECTIVES: The aim of this study was to evaluate hard and soft tissues around implants placed in posterior mandible 1 year after vertical ridge augmentation (VRA). MATERIALS AND METHODS: 40 patients with vertical defects were enrolled and treated according to the study protocol. Patients were randomly divided into two study groups: reinforced PTFE membranes (group A) and titanium meshes plus collagen membranes (group B). All patients received simultaneous implants which were evaluated after prosthetic restoration at baseline and after 1 year, using the following parameters: peri-implant bone levels (PBLs), interproximal bone peaks (IBPs), pocket probing depth (PPD), bleeding on probing (BoP), plaque index (mPI), gingival index (mGI), keratinized tissue thickness/width (tKT and wKT), and fornix depth (FD). Statistical analysis was performed to investigate any statistically significant differences and/or correlations (p = .05). RESULTS: 30 patients were completely followed up according to the study protocol. After 1 year, implants showed a change in PBL from 0.12 to 0.76 mm, with marginal bone loss of 0.67 and 0.61 mm for group A and group B, respectively, without significant differences (p > .9337). The estimated difference between treatments for the change from baseline in PBL was -0.05 (95% CI -0.27 to 0.16). Statistical analysis revealed strong correlations between PBL and IBP (p < .0001). However, no significant differences were observed for PPD, mPI, mGI, tKT, wKT, and FD (p > .05). CONCLUSION: The results indicate that GBR treatment with titanium meshes plus collagen membranes (Group B) compared to reinforced PTFE membranes does not appear to be inferior or superior in terms of PBL change. In both groups, hard and soft tissues were stable after 1 year of follow-up, with a peri-implant bone loss less than 1.0 mm in the first year (study registered at ClinicalTrials.gov NCT04332679).

Clinical and volumetric outcomes after vertical ridge augmentation using computer-aided-design/computer-aided manufacturing (CAD/CAM) customized titanium meshes: a pilot study.

BACKGROUND: One of the most recent innovations in bone augmentation surgery is represented by computer-aided-design/computer-aided-manufacturing (CAD/CAM) customized titanium meshes, which can be used to restore vertical bone defects before implant-prosthetic rehabilitations. The aim of this study was to evaluate the effectiveness/reliability of this technique in a consecutive series of cases. METHODS: Ten patients in need of bone augmentation before implant therapy were treated using CAD/CAM customized titanium meshes. A digital workflow was adopted to design virtual meshes on 3D bone models. Then, Direct Metal Laser Sintering (DMLS) technology was used to produce the titanium meshes, and vertical ridge augmentation was performed according to an established surgical protocol. Surgical complications, healing complications, vertical bone gain (VBG), planned bone volume (PBV), lacking bone volume (LBV), regenerated bone volume (RBV), average regeneration rate (RR) and implant success rate were evaluated. RESULTS: All augmented sites were successfully restored with definitive implant-supported fixed partial dentures. Measurements showed an average VBG of 4.5 ± 1.8 mm at surgical re-entry. Surgical and healing complications occurred in 30% and 10% of cases, respectively. Mean values of PBV, LBV, and RBV were 984, 92, and 892 mm3, respectively. The average RR achieved was 89%. All 26 implants were successfully in function after 1 year of follow-up. CONCLUSIONS: The results of this study suggest that the bone augmentation by means of DMLS custom-made titanium meshes can be considered a reliable and effective technique in restoring vertical bone defects.

Evaluation of Crestal Bone Loss Around Straight and Tilted Implants in Patients Rehabilitated by Immediate-Loaded Full-Arch All-on-4 or All-on-6: A Prospective Study.

The aim of this prospective study was to compare implant success rate and crestal bone loss around tilted and straight implants supporting immediate-loading full-arch rehabilitations. Twenty consecutive patients with edentulous jaws treated between June 2013 and July 2015 who satisfied all inclusion and exclusion criteria were included in the study. All patients were rehabilitated through a full-arch restoration supported by 4 or 6 immediately loaded implants. Clinical and radiographic examinations were scheduled every 12 months to evaluate implant success rates and crestal bone levels. Significant differences in crestal bone levels and success rates between straight and tilted implants were investigated by means of independent statistical analysis; differences were regarded as significant if P < .05. Seventy straight and 50 tilted implants were placed to rehabilitate 14 mandibles and 12 maxillae in 20 patients. After a follow-up of 12 to 36 months, survival rate was 97.1% for straight implants and 96.0% for tilted implants; while success rates were 94.3% and 94.0%, respectively. Success and survival rates were not significantly different (P > .05). Change in crestal bone level was 0.5 ± 0.4 mm for straight implants and 0.6 ± 0.4 mm for tilted implants (P > .05). Straight and tilted implants seemed to have similar behavior after immediate loading rehabilitations. After functional loading, straight and tilted implants did not differ significantly in clinical outcome.

Histological and histomorphometric analysis of bone tissue after guided bone regeneration with non-resorbable membranes vs resorbable membranes and titanium mesh.

BACKGROUND: Guided bone regeneration (GBR) allows to achieve vertical ridge augmentation whether with nonresorbable membranes or resorbable membranes with Ti-mesh, but till now no studies are published comparing histological and histomorphometrical outcomes of these two procedures. MATERIALS AND METHODS: Forty partially edentulous patients required vertical bone regeneration to place implants in the posterior mandible: 20 patients were randomly assigned to group A (Ti-PTFE); while 20 patients to group B (Collagen plus Ti-mesh). For both groups, graft material was a 50:50 mixture of autogenous bone and bone allograft. After 9 months, tissue biopsies were taken from augmented sites (regenerated bone ROI-1; native bone ROI-2) and undergone to histological and histomorphometric analysis. Percentages of bone tissue (B.Ar), biomaterial (Mat. Ar), and soft tissue (St.Ar) were measured; measurements of perimeters were calculated too. ROI-1 values were also compared to ROI-2 in both groups. RESULTS: Twenty-five samples were collected and analyzed consecutively: 13 in group A and 12 in group B. The mean B.Ar, Mat.Ar, and St.Ar were 39.7%, 8.6%, and 52.1% in group A; similar results were obtained in group B, with mean values of 42.1%, 9.6%, and 48.3%, respectively. No significant statistically differences were observed. Differences were observed between ROI-1 and ROI-2 in both group. Finally, bone structure index of ROI-1 and ROI-2 showed statistical differences. CONCLUSIONS: The preliminary results of this study suggest that GBR using nonresorbable membranes and Ti-mesh with resorbable membranes in combination with autogenous bone and bone allograft provide similar histological and histomorphometric results.

A Proposal of Pseudo-periosteum Classification After GBR by Means of Titanium-Reinforced d-PTFE Membranes or Titanium Meshes Plus Cross-Linked Collagen Membranes.

After guided bone regeneration (GBR) with different devices, a layer of connective tissue called pseudo-periosteum can be observed above the newly formed bone. The aim of this study is to evaluate the clinical and histologic features and to suggest a classification of this connective tissue after GBR with nonresorbable membranes or titanium (Ti)-mesh plus resorbable membranes. Forty patients with partial edentulism in the posterior mandible were randomized into two groups: 20 patients were treated by means of Ti-reinforced dense polytetrafluoroethylene (d-PTFE) membrane (group A), while the other 20 patients were treated with Ti-mesh and a cross-linked collagen membrane (group B). After 9 months and during re-opening surgery, bone density and pseudo-periosteum type were recorded. Pseudo-periosteum was classified into Type 1 (no tissue or tissue < 1 mm); Type 2 (regular tissue between 1 and 2 mm); and Type 3 (irregular tissue or tissue > 2 mm). Histologic analyses were performed to identify the features of pseudo-periosteum. Out of 40 patients, 36 (n = 19 in Group A; n = 17 in Group B) with 99 implants were analyzed after GBR and according to the study protocol. The vertical bone gain was 4.2 ± 1.0 mm in Group A and 4.1 ± 1.0 mm in Group B. Group A had a higher bone density and greater amounts of type 1 periosteum than Group B (P = .01 for both). The preliminary results of this study show that both d-PTFE membranes and Ti-mesh plus collagen membranes are two valid options for bone augmentation in the mandible. However, nonresorbable membranes achieve higher bone density and a thinner pseudo-periosteum layer above the newly formed bone.

Coronectomy: A Surgical Option for Impacted Third Molars in Close Proximity to the Inferior Alveolar Nerve-A 5-Year Follow-Up Study.

PURPOSE: The extraction of third molars is the most common surgical procedure performed in the oral cavity. Coronectomy is a surgical protocol to reduce the risk of neurologic lesions to the inferior alveolar nerve (IAN). We evaluated early (up to 1 month) and late (from 2 to 60 months) postoperative complications. MATERIALS AND METHODS: This prospective cohort study enrolled patients treated at the Unit of Oral and Maxillofacial Surgery, University of Bologna. The predictor variable was the time after coronectomy with up to 5 years' follow-up. To assess the rate of postoperative complications, the outcome variables were neurologic injuries, postoperative pain, swelling, fever, alveolitis, pulpitis, and root exposure. The success rate, need for a second surgical procedure, probing pocket depth, and bleeding on probing also were investigated. Univariate and bivariate descriptive statistics, Kaplan-Meier analysis, and Cox hazards modeling were performed to evaluate the variables. RESULTS: We performed 116 coronectomies in 94 healthy patients (37 men and 57 women; mean age, 28.99 ± 8.9 years). At 5 years' follow-up, we re-evaluated 63 patients with 76 coronectomies. In total, 30 complications were verified. No cases of neurologic lesions to the IAN or lingual nerve were observed after surgery. In the first 3 years, the surgeons extracted migrated roots in 5 cases (6%) without any neurologic lesions to the IAN. No complications were observed from the third to fifth year. CONCLUSIONS: This prospective study on coronectomy of third molars in a close relationship with the mandibular canal found no cases of neurologic lesions, no cases of late infection of the retained roots at 5 years, and a low rate of immediate postoperative complications. Further investigations should include a follow-up study at 10 years and more research about the mechanism of pulp healing.

Stability of Periodontal Healing Distal to the Mandibular Second Molar After Third Molar Coronectomy: A 3-Year Follow-Up Study.

PURPOSE: The stability of the periodontal attachment distal to the mandibular second molar after coronectomy of the third molar is still unclear. This study addressed the question of whether periodontal measures are stable over time among patients undergoing coronectomy. MATERIALS AND METHODS: This prospective cohort study enrolled 30 patients treated at the Unit of Oral and Maxillofacial Surgery of the University of Bologna. The predictor variables were the probing pocket depth (PPD), distance between the marginal crest and the bottom of the osseous defect (BOD), and distance between the cementoenamel junction and the BOD. Three points on the distal surface of the second molar were recorded: distobuccal, distomedial, and distolingual sites. The distobuccal site was used as the statistical unit. The Wilcoxon test for paired data and Kendall τb were used to evaluate all variables. The significance level was set at P < .05. RESULTS: The 3-year follow-up was completed by 27 patients (7 male and 20 female patients; mean age, 28 ± 7 years) with 30 third molars. At 3 years, the PPD was 4 ± 1.25 mm; no significant changes in PPD were recorded for all sites from 9 months to 3 years. For the marginal crest-BOD distance and the cementoenamel junction-BOD distance, significant reductions were evident between preoperative values and those at 9 to 36 months (P = .001) and between values at 9 and 36 months (P = .02). CONCLUSIONS: A clinical healthy periodontium distal to the second molar was observed 36 months after coronectomy. However, further studies are necessary to confirm these preliminary clinical results.

Tapered, Double-Lead Threads Single Implants Placed in Fresh Extraction Sockets and Healed Sites of the Posterior Jaws: A Multicenter Randomized Controlled Trial with 1 to 3 Years of Follow-Up.

PURPOSE: To evaluate the survival, success, and complication rates of tapered double-lead threads single implants, placed in fresh extraction sockets and healed sites of the posterior jaws. METHODS: The enrolled patients were randomly divided into 2 groups: in the test group (TG), all implants were inserted at the time of tooth extraction; in the control group (CG), all implants were placed 3 months after extraction. The implants were followed for a period of 1 to 3 years after loading. The main outcomes were implant survival, complications, and implant-crown success. RESULTS: Ninety-two patients had 97 installed implants (49 in the TG, 48 in the CG). Only two implants failed, in the TG; the survival rates were therefore 95.9% (47/49) and 100% (48/48) for TG and CG, respectively. In the surviving implants, no complications were reported, for an implant-crown success of 100%. CONCLUSIONS: Although a significant difference was found in the levels of primary stability between TG and CG, single implants placed in fresh extraction sockets and healed sites of the posterior jaws had similar survival and complication rates. Crestal bone levels and peri-implant bone resorption showed similar values. A longer follow-up period is however required, to confirm these positive outcomes.

Evaluation of complication rates and vertical bone gain after guided bone regeneration with non-resorbable membranes versus titanium meshes and resorbable membranes. A randomized clinical trial.

BACKGROUND: The partial edentulous posterior mandible is often a challenge area that requires a bone reconstructive surgery for implants placement. PURPOSE: This RCT was aimed to evaluate complications rate and vertical bone gain after Guided Bone Regeneration (GBR) with dense non-resorbable d-PTFE titanium-reinforced membranes (Group A) versus titanium meshes covered by cross-linked collagen membranes (Group B). MATERIAL AND METHODS: 40 partially edentulous patients with atrophic posterior mandible, were randomly divided into two study group: 20 patients were treated with one stage GBR by means of non-resorbable d-PTFE titanium-reinforced membranes (Group A); and 20 patients, by means of titanium mesh covered by cross-linked collagen membranes (Group B). All complications were recorded, distinguishing between "surgical" and "healing" and between "minor" or "major.". Primary implants stability and vertical bone gain were also evaluated. RESULTS: In the group A, surgical and healing complication rates were 5.0% and 15.0%, respectively. In the group B, surgical and healing complication rates were 15.8% and 21.1%, respectively. No significant differences between two study group were observed regarding complications rate implant stability and vertical bone gain. CONCLUSIONS: Both GBR approaches for the restoration of atrophic posterior mandible achieved similar results regarding complications, vertical bone gain and implant stability.

Minimally Invasive Approach Based on Pterygoid and Short Implants for Rehabilitation of an Extremely Atrophic Maxilla: Case Report.

INTRODUCTION: Extremely atrophic maxillae can be considered the most important indication for three-dimensional maxillary reconstruction. Different bone-augmentation techniques have been suggested to accomplish this. This article illustrates a minimally invasive approach to rehabilitation of the extremely atrophic maxilla. MATERIAL AND METHODS: A 63-year-old male patient was referred for restoration of his totally edentulous maxilla with a fixed full-arch implant-prosthetic rehabilitation. Four short implants in the premaxillary region and 2 longer implants in the pterygomaxillary regions were inserted with piezoelectric implant site preparation. DISCUSSION: At the 1-year follow-up appointment, no clinical or radiographic changes in the soft-tissue contours or crestal bone levels were observed. CONCLUSION: This surgical approach, based on the combination of short implants in the premaxillary regions and pterygoid implants in the pterygomaxillary regions, represents a way to shorten treatment timing, minimize the risk of surgical complications, and reduce patient discomfort and costs.

Periodontal Healing Distally to Second Mandibular Molar After Third Molar Coronectomy.

PURPOSE: Coronectomy of mandibular third molars is a procedure that still raises a number of questions. The aim of the present study was to answer one unsolved question: the periodontal healing distal to the mandibular second molar after third molar coronectomy. MATERIALS AND METHODS: A prospective cohort study was performed of 30 patients treated at the Unit of Oral and Maxillofacial Surgery of the Department of Biomedical and Neuromotor Science of the University of Bologna. The predictor variables were the probing pocket depth (PPD), the distance between the marginal crest (MC) and the bottom of the osseous defect (BOD), and the distance between the cementum enamel junction (CEJ) and the BOD. These clinical indexes were recorded on 3 points of the distal surface of second molar: the distobuccal (DB), distomedial (DM), and distolingual (DL) sites. The other variables evaluated included root migration and postoperative complications. The Wilcoxon test for paired data and Kendall's tau-b correlation coefficient was used to evaluate all variables. The significance level was set at P = .05. RESULTS: The cohort was composed of 30 patients with 34 high-risk mandibular third molars (9 men and 21 women), with a mean age of 28 ± 7 years. At 9 months, a statistically significant reduction in the PPD of 2 ± 3, 1 ± 2, and 2 ± 2 mm and a statistically significant reduction in the MC-BOD distance of 4 ± 4, 4 ± 4, and 4 ± 5 mm for the DB, DM, and DL sites, respectively, was observed (P = .001). Also, the intraoperative CEJ-BOD distance showed a statistically significant reduction for the DB, DM, and DL sites. CONCLUSIONS: After coronectomy, restoration of a clinical healthy periodontium distal to the second molar was observed. However, further studies are necessary to confirm these preliminary clinical results and to compare periodontal healing between coronectomy and complete extraction.

Coronectomy of mandibular third molars: A clinical protocol to avoid inferior alveolar nerve injury.

Coronectomy is a surgical procedure for the treatment of mandibular third molars in close proximity to the mandibular canal. Unfortunately, often the surgical protocol is not described step by step and it is difficult for the clinician to assess the key factors that are important for the success of this procedure. The aim of this paper is to propose and describe a standardized surgical protocol to improve the success of the technique. The treatment approach, for the most common types of third molars impaction is analysed. Each step of the surgical procedure is described in details and a new type of crown section is proposed. The presented protocol is proposed in order to define a clinical practitioner's guide that could help the surgeon who approaches coronectomy for the first times.

Root Fragment Vitality After Coronectomy: Histological Evidence in a Case.

PURPOSE: Coronectomy is a well-documented surgical technique for the treatment of high-risk third molars, but the fate of retained roots remains controversial. This case report describes the histologic analysis of retained root fragments. PATIENT AND METHODS: A 44-year-old man treated with coronectomy of a left mandibular third molar requested the extraction of the retained roots. The patient was asymptomatic and the retained roots were extracted 18 months after coronectomy at the patient's request. RESULTS: The extracted roots were histologically evaluated and the results showed the presence of vital pulp tissue. CONCLUSION: Histologic analysis showed that retained roots remain vital after coronectomy.

What Are the Types and Frequencies of Complications Associated With Mandibular Third Molar Coronectomy? A Follow-Up Study.

PURPOSE: Coronectomy has been proposed for impacted third molars in close proximity to the inferior alveolar nerve (IAN) to avoid neurologic injury. Immediate (up to 1 month) and late (2 to 36 months) postoperative complications were investigated. MATERIALS AND METHODS: A prospective cohort study was performed on healthy patients treated in the dental clinic of the Department of Oral Surgery, University of Bologna. The predictor variables examined were experience of the surgeon (<10 vs ≥10 yr), length of surgery, type of mandibular third molar inclusion, and patient age. To assess the rate of postoperative complications, outcome variables were neurologic injuries, postoperative pain, swelling, fever, alveolitis, pulpitis, and root exposure. The success rate and need for a second surgery also were investigated. Univariate and bivariate descriptive statistics, Kaplan-Meier analysis, and Cox hazards modeling were performed to evaluate the variables. RESULTS: The study involved 94 healthy patients (mean age, 28.99 ± 8.9 yr; range, 17 to 56 yr; 37 men and 57 women) who had 116 third mandibular molars treated with coronectomy. During the 3-year follow-up period, 28 patients (29 coronectomy procedures) dropped out of the study. There was no case of neurologic injury to the inferior alveolar nerve (IAN) or to the lingual nerve (LN). In total, 30 complications were observed (25 within 1 month; 5 at 2 to 12 months). Surgeons with less than 10 years of training exposed patients to a greater risk of complications (hazard ratio = 2.069; 95% confidence interval, 1.004-4.263). An overall success rate of 74% at 6 months was estimated, and a second surgery was needed in 6% of cases. Of the retained roots analyzed, 80% showed postoperative root migration. CONCLUSIONS: In this study, coronectomy of mandibular third molars did not result in temporary or permanent injury to the IAN or LN. Coronectomy showed a low rate of postoperative complications. However, within the first year, a second surgery was needed in 6% of coronectomy procedures to remove migrated root fragments. Additional studies with larger patient samples are recommended to further investigate differences in postoperative complications in relation to patient age.