A clinical evaluation of cobalt-chromium metal-ceramic fixed partial dentures fabricated by dmls and conventional cast methods

In recent years, metal-ceramic fixed partial dentures fabricated by direct metal laser sintering (DMLS) have been used as an alternative to metal-ceramic fixed partial denture fabricated by conventional casting procedures. Advantages of DMLS like high mechanical properties, low production times and expences over conventional casting methods have been reported in previous studies. However clinical studies for evaluating clinical performance of DMLS are limited. The aim of this clinial study was to evaluate and compare chippings type of failure in Co-Cr metal-ceramic restorations fabricated by DMLS or conventional cast methods. The test group consisted of 75 patients who applied to the prosthodontics department of Cukurova University in a need of fixed partial dentures without any sign of bruxial behaviors or symptoms. The patients were divided into two groups randomly. In the first group metal substructure of restorations were fabricated by laser sintering using Co-Cr alloy powder. In the second group substructures were fabricated by using lost-wax technique using Co-Cr alloy ingots. Patients recall and clinical examinations of the prostheses were done 6-9 months after the cementation. The chippings in metal-ceramic restorations were evaluated and classified. Student T, Mann Whitney U, Ki Square and Fisher tests were used in statistical analysis. (α=0.005) The success rate was found 96.9% and the survival rate was found 98.7% in terms of chipping among all patients. There were no statisticaly significant differences between DMLS group (3.8%) and cast group (2.6%) in terms of chipping. Also, no statisticaly significant differences in chipping was found between the DMLS (17.9) and casting (22.2%) patient groups. When comparing groups about opposing dentition there was statisticaly significant diffrence (p=0,001). There was no statisticaly significant differences between groups in terms of chipping grades. The chipping in male patients (5.8%) were significantly higher than female patients (1.4%). Within the limitations of the current study it was concluded that occurance of chipping in metal-ceramic fixed partial dentures fabricated by either DMLS or conventional casting methods showed statisticaly no significant differences.