A randomized controlled clinical trial of two materials for implant-supported provisional prostheses

16277 ORAL COMMUNICATION CLINICAL RESEARCH – PROSTHETICS

Background

In many occasions, the fabrication of implant-supported prostheses requires the use of long-term provisional prostheses to achieve optimal results. This treatment demands the use of polymeric materials with excellent mechanical and optical properties, as well as a clinically acceptable marginal fit. In this sense, computer-aided design computer-aided manufacturing (CAD CAM) polymers are the most suitable materials.

Aim/Hypothesis

To evaluate the clinical performance of posterior all-resin provisional implant-supported fixed partial dentures (FPDs) made of two different CAD CAM materials- polymethylmethacrylate (PMMA) and polyoxymethylene (POM).

Material and Methods

Twenty-one patients were randomly selected for the placement of implant-supported prostheses. The same patient received the PMMA as part of the control group and the POM as part of the experimental group, in random order and without knowing which material was placed in each moment. Restorations were evaluated at one week and 3 and 6 months after their placement, using the California Dental Association (CDA) quality evaluation index. Color stability was also evaluated with a spectrophotometer in a specific box under standard conditions. This evaluation considered the average result of three measurements, always conducted in the same piece, and with the spectrophotometer in a perpendicular position. The same operator did all measurements, without knowing the time of the study or the type of material. Several dental implants systems and implant-abutment connections were included in this study. Data were analyzed using nonparametric statistics, and statistical significance was set at 0.05.

Results

A total of 50 prostheses were placed, but one patient dropped out after the fracture of his PMMA prosthesis. Thus, 25 PMMA and 24 POM prostheses (n = 49) were evaluated. Among these, 28 were of 2 pieces, 17 of 3 pieces and 4 of 4 pieces, constituting a total of 123 pieces. Several prostheses fractured throughout the study in different moments, so, the number of prostheses at 3 and 6 months was lower than the initial number. All CDA parameters decreased over time in both groups, with no statistically significant differences. The only significant differences between the two materials were found in the color and surface parameters, with PMMA establishing more favorable scores at all moments (P < 0.05). Fractures at the implant connection level were observed in 10 prostheses. Internal conical connection implants had significantly more fractures (P < 0.05). The statistical analysis of chromatic stability showed ΔE*ab values of 7.18 for PMMA and 8.58 for POM, without significant differences.

Conclusion and clinical implications

Within a 6-month observation period, PMMA provisional implant-supported FPDs had better surface and color parameters than POMís. This study suggests that posterior implant-supported FPDs made entirely of polymers seems to be more susceptible to fracture when used with internal conical connection implants. However, the small sample size must be considered when drawing clinical recommendations, and more studies are required to support the successful long-term use of polymers.