Fit accuracy assessment of removable partial denture frameworks produced by direct metal laser sintering - a clinical trial.

OBJECTIVES

The purpose of this cross-over clinical study was to compare the number of framework repetitions, percentage of framework components adjusted, clinical acceptability, and fit accuracy of removable partial denture frameworks produced by the direct metal laser sintering technique (DMLS) and conventional technique.

MATERIALS AND METHODS

For each dental arch (n = 26), two cobalt-chromium frameworks were produced through two protocols: direct metal laser sintering (experimental group) and conventional lost-wax casting technique (control group). The number of framework repetitions, the percentage of components that had to be adjusted, and the clinical acceptability were registered. The fit accuracy of functional components was assessed by a qualitative method using endodontic files to identify maladjustments and compared to a quantitative method based on silicone specimens digitized by micro-computed tomography. The normality was checked (Shapiro-Wilk test), and data were analyzed with McNemar, Wilcoxon and paired-t tests (α = 0.05).

RESULTS

No statistically significant differences were found between conventional and digital frameworks for most of the variables tested (p > 0.05) except the fewer laboratory repetitions (p = 0.046), higher percentage of components adjusted (p = 0.011), and better reciprocal arms fit (p = 0.044) in the frameworks produced by DMLS protocol. No statistically significant (p = 0.174) difference was found between the fit accuracy qualitative and quantitative assessment methods.

CONCLUSIONS

The DMLS and conventional protocols were similar. Despite the DMLS protocol exhibiting a higher percentage of components adjusted, it presented better reciprocal arms fit accuracy with no framework repetition.

CLINICAL RELEVANCE

Metal frameworks can be produced using DMLS eliminating casting problems.