Compliance of dental laboratory technicians with dentists’ instructions for fabrication of a PFM crown

Abstract

Objectives

The aim of this study was to evaluate the compliance of dental technicians from different dental laboratories with dentists’ written prescriptions during fabrication of porcelain-fused-to-metal (PFM) crowns.

Materials & methods

Final impressions for a prepared Ivorine tooth no. 21 were sent to 16 dental laboratories (8 government and 8 commercial) for fabrication of a PFM crown. A detailed, standard work authorization form accompanied each case, including a request to fabricate a uniform-thickness metal framework, with incisal translucency, hypocalcification-like stain, porcelain facial shoulder and metal palatal chamfer margins with palatal occlusion in porcelain. All crowns were then collected, and data were recorded and analyzed statistically with Fisher’s Exact and Pearson’s Chi-square tests by means of SPSS and WinPepi software.

Results

No statistically significant differences were found between laboratory groups in following the instructions for metal substructure thickness (P > 0.6), facial and palatal margins (P = 1.0) or the dimensions of the hypocalcification-like stain (P = 0.28). However, commercial labs were significantly better than government labs in the location criteria for hypocalcification and incisal translucency (P = 0.04). When the total numbers of successfully followed criteria were compared, commercial labs were found to be significantly better than government labs in following the written instructions (P = 0.002).

Conclusion

Although a standard work authorization form was used, commercial labs performed better than government labs, especially in esthetic characterizations such as hypocalcification-like staining and incisal translucency.