Prosthetic complications with mandibular bar-retained implant overdentures having distal attachments and metal frameworks: A 2- to 12-year retrospective analysis.

STATEMENT OF PROBLEM Long-term reports on 2-implant-retained overdentures having metal frameworks and bars containing distal attachments are scarce. PURPOSE The purpose of this retrospective study was to evaluate prosthetic complications with 2-implant-retained mandibular overdentures with metal frameworks having either screw- or cement-retained cantilevered bars with distal attachments. MATERIAL AND METHODS Seventy-three edentulous study participants who had been treated with mandibular overdentures with 2 implants were included. The parameters assessed were acrylic resin fractures (base fracture, fracture at midline), debonding of teeth, opposing prosthesis fracture, need for relining or rebasing, abutment and bar screw loosening and fracture, ball or bar attachment or clip wear, fracture or detachment, bar fracture, and implant loss. Statistical analysis was performed by using the Mann-Whitney U test as the data were not normally distributed. The categorical variables between the groups were analyzed by using the Fisher exact test (α=.05). RESULTS Twenty-seven prostheses had a cement-retained bar, and 46 bars were screw-retained. Of 73 overdentures, 68 were metal-reinforced. The mean observation time was 5.9 years with a range between 2 and 12 years. The most common complication was wear of the Rhein 83 polymer attachment followed by bar screw loosening. The cumulative survival rate for overdentures was 91.9% at 6.8 years. The service life of cement-retained prostheses was significantly longer (P.05). CONCLUSIONS Based on the participant population observed, the survival rates of 2-implant-retained mandibular overdentures and their implants in the medium term were high. Wear of the polymer attachment was commonly seen. Overdentures with cement-retained bars had bar or acrylic resin fractures. Mandibular 2-implant-retained overdentures with a screw-retained bar containing bilateral distal attachments had fewer prosthetic complications and high implant survival in the medium term

Marginal Adaptation of Provisional CAD/CAM Restorations Fabricated Using Various Simulated Digital Cement Space Settings

Purpose: The ideal digital cement space value for the fabrication of provisional computer-aided design/ computer-aided manufacturing (CAD/CAM) crowns with clinically acceptable marginal adaptation is not well known. The aim of this study was to evaluate the effect of different simulated cement space settings on the marginal tit of poly(methyl methacrylate) (PMMA) provisional CAD/CAM restorations. Materials and Methods: An extracted premolar tooth was prepared using ceramic crown preparation guidelines and represented both natural teeth and/or custom implant abutments. The prepared tooth abutment was scanned with a three-dimensional (3D) laboratory scanner (D900, 3Shape). CAD design software was used to subsequently design a premolar crown core with three different simulated cement space settings (20 to 40 mu m, 20 to 50 mu m, 20 to 60 mu m). PMMA blocks were used to mill the specimens (n = 9, N = 27). Using a stereo zoom microscope, a total of 36 images for each of the 3 groups (9 crowns per group, 4 sites per crown) were captured to measure the mean vertical marginal discrepancy for every group. One-way analysis of variance (ANOVA) was used to analyze the data, and the post hoc Tukey multiple comparison test was performed. Results: The marginal gap values of the PMMA cores fabricated using the three cement space settings were significantly different from each other (P < .001). The marginal gap was smaller with a 20- to 60-mu m setting compared with 20 to 50 mu m and 20 to 40 mu m, and the 20- to 50-mu m setting allowed for smaller marginal gaps compared with 20 to 40 mu m (P < .001). Conclusion: Within the limitations of this study, the marginal gaps of CAD/CAM-fabricated PMMA cores were smaller when the cement space was larger. The smallest marginal gaps were achieved when a 20- to 60-mu m cement space was used (P < .001)

Clinical Performance of Samfilcon A Contact Lenses in Intensive Digital Device Users: A Multicenter, Prospective Clinical Study

Introduction To evaluate patient satisfaction with samfilcon A contact lenses (CLs) in intensive digital device users with myopia and to compare patient satisfaction with samfilcon A lenses to prior experience with senofilcon A or lotrafilcon B CLs. Methods This was a comparative, prospective, national study conducted at 14 centers in Turkey. Subjects were adults aged 18 and 45 years with myopia (range -0.25 D to -6.00 D) who spend a minimum of 3 hours viewing digital devices (e.g., computer, smartphone). A subgroup of patients were habitual lens wearers (senofilcon A or lotrafilcon B lens wear for at least 6 months prior to enrollment). The primary assessment was patient satisfaction with samfilcon A lenses (0-100 Likert scale). Secondary assessments included patient satisfaction with samfilcon A lenses compared to patients' habitual lenses, investigator satisfaction with samfilcon A lenses and investigator-evaluated slit lamp examination findings. Results Samfilcon A lenses were given high overall ratings from both patients and investigators, with a low incidence of ocular symptoms. Overall, patients were highly satisfied with samfilcon A lenses for comfort, vision and overall performance, and stated that they would consider wearing these lenses in the future. Among habitual senofilcon A or lotrafilcon B lens wearers, samfilcon A lenses were rated significantly better than the habitual lenses in regard to comfort, vision and overall performance. Investigator assessments were also highly favorable, both at initial fit and after 4 weeks of follow-up, with no significant findings noted on slit lamp examination. Conclusion Samfilcon A lenses were rated highly by investigators in regard to fit, handling and slit lamp findings, and by novice and habitual lens wearers in regard to comfort, vision and overall performance. These results support the use of samfilcon A lenses among digital device users who seek day-long comfort and good visual acuity