Effect of Post-Casting Cooling Rate on Clasp Complications in Co–Cr–Mo Removable Partial Dentures: 5-Year Retrospective Data

This retrospective study aimed to evaluate the five-year clinical performance of removable partial dentures (RPDs) made of chromium–cobalt–molybdenum alloy, comparing two different post-casting cooling methods: slow furnace cooling (LRF) and room temperature air cooling (RATA). The investigation aimed to determine whether LRF treatment could reduce the incidence of technical complications, such as fractures and clasp deformations, particularly on RPD with thin clasps for aesthetic reasons. Methods: In total, 22 RPDs were examined, 11 of which were treated with LRF (test group) and 11 with RATA (control group). The prostheses in the LRF group had clasps intentionally reduced by 2/3 tenths of a millimeter compared to those in the RATA group. All the prostheses were made and evaluated by the same operator, who analyzed the presence of changes, fractures, or clasp widening after five years. Statistical analysis was performed using Fisher’s exact test with a significance level of p < 0.05. Results: Clinical data showed a lower complication rate in the LRF group compared to the RATA group in all parameters evaluated: prosthesis modification (9.1% vs. 18.2%), clasp fractures (9.1% vs. 36.4%), and enlarged clasps (54.4% vs. 72.7%). However, the statistical comparison between the two groups did not show significant differences, p-value > 0.05 for all parameters. Conclusions: Despite the lack of statistical significance, likely due to the limited size of the cambium and the confounding variable of clasp thickness, clinical trends indicate a potential superiority of the LRF method in the parameters examined, such as modification prosthesis, fractured clasp, and enlarged clasp. The reduction in complication rates in the LRF group suggests that the superior mechanical properties conferred by this treatment may compensate for the potential structural weakening caused by clasp thickness. Future studies with a larger sample size and a prospective design will be needed to validate these