Introduction: This study evaluated the prepared surface areas of oval-shaped canals in distal roots of mandibular molars using four different instrumentation techniques. Methods: Teeth were prescanned and reconstructed using micro-computed tomography (MCT) scans at low resolution (68 mm). Forty-eight molars with ribbonshaped/oval distal root canals were selected and randomly assigned to four groups. Distal canals (n = 12 each) were prepared by circumferential filing using Hedströ m files to apical size #40 (group H/CF); with ProTaper nickel-titanium rotaries to finishing file 4 (F4) considering the distal canal as 1 canal (group PT/1); ProTaper to F4 considering buccal and oral aspects of the distal canal as 2 individual canals (group PT/2); ProTaper to F4 in a circumferential filing motion (PT/CF). Before and after shaping, teeth were evaluated using MCT at 34-mm resolution. The percentage of prepared surface was assessed for the full canal length and the apical 4 mm. Statistical analysis was performed using analysis of variance and Bonferroni/Dunn multiple comparisons. Results: Preoperatively, canal anatomy was statistically similar among the groups (p = 0.56). Mean (± standard deviation) untreated areas ranged from 59.6% (±14.9, group PT/2) to 79.9% (±10.3, PT/1) for the total canal length and 65.2% to 74.7% for the apical canal portion, respectively. Canals in group PT/1 had greater untreated surface areas (p < 0.01) than groups PT/2 and PT/CF. Among all groups, amounts of treated surface areas were statistically similar in the apical 4 mm. Conclusions: Preparations of ovalshaped root canals in mandibular molars left a variable portion of surface area unprepared regardless of the instrumentation technique used. However, considering oval canals as two separate entities during preparation appeared to be beneficial in increasing overall prepared surface. (J Endod 2010;36:703-707)

At 10 years, ZC and MC posterior FDPs resulted in similar outcomes for the majority of the outcome measures (p > 0.05).

Aim To evaluate the clinical and radiological outcomes of one‐piece zirconia implants restored with single crowns (SCs) or fixed dental prostheses (FDPs) over an observation period of 5 years in function. Materials and methods In a prospective cohort investigation with two investigational centers, one‐piece zirconia implants were placed in anterior and posterior sites. After a healing period of at least 2 months in the mandible and 4 months in the maxilla with immediate provisional reconstructions, the final all‐ceramic SCs or three‐unit FDPs were cemented. Patients were followed for 5 years. Clinical parameters and radiological measurements of the implants and the neighboring teeth were assessed. For the statistical analysis, linear mixed models were applied. Results A total of 71 implants were placed in 60 patients. Sixty‐three implants in 53 patients could be evaluated at the 5‐year follow‐up. Six patients with a total of seven implants were counted as dropouts. One implant did not achieve adequate osseointegration and had to be removed 5 weeks after implantation. The 5‐year survival rate was calculated as 98.4% (95% CI 91.6, 99.9). The mean overall marginal bone loss from implant placement to the 5‐year follow‐up was 0.7 ± 0.6 mm. After an initial mean marginal loss before loading the implants (0.7 mm), no further statistically significant change in marginal bone level (p = .458) could be observed. Conclusion The investigated one‐piece zirconia implant showed a high survival rate, very stable marginal bone, and mucosal margin levels after 5 years in function. Therefore, it can be considered safe and reliable for the reconstruction of implant‐supported SCs or FDPs over a mid‐term period.

The aim of this study was to test whether posterior zirconia-ceramic (ZC) and metalceramic (MC) fixed dental prostheses (FDPs) exhibit similar survival and technical/biologic complication rates. Materials and Methods: A total of 58 patients in need of 76 posterior FDPs were randomly assigned to receive 40 ZC and 36 MC FDPs. The restorations were examined at baseline (cementation) and yearly for 5 years. Technical and biologic outcomes were compared. The independent treatment groups were compared with nonparametric Mann-Whitney test for metric variables and with Fisher exact test for categoric data. Results: A total of 52 patients with 40 ZC and 29 MC FDPs were examined at 5 years. No FDP failed during the 5 years; 2 ZC FDPs failed at 65.4 and 73.3 months. Debonding occurred at 3 ZC FDPs. Technical outcomes (modified US Public Health Service criteria) and general periodontal parameters did not show significant differences between ZC and MC FDPs. Conclusion: ZC FDPs exhibited similar outcomes to MC FDPs based on 5-year survival estimates. The majority of technical and biologic outcome measures were not significantly different.

Interventions aimed for alveolar ridge preservation have shown efficacy in terms of allowing the placement of dental implants and for reducing the need of further augmentation procedures at implant placement. Both therapeutic options, the placement of implants after sinus elevation and grafting or short dental implants, were valid alternatives in the treatment of the posterior maxilla with deficient bone availability, although short implants resulted in fewer complications. Similarly, the placement of implants in vertically augmented bone rendered comparable outcomes with those of short implants in the treatment of the posterior mandible, but short implants resulted in fewer complications.