Analysis of Resistance Form of Molar Crown Preparations for Full-Coverage Porcelain Fused to Metal Crowns: A Prospective Study at The University of Ghana Dental School

Background: A good molar crown preparation with adequate resistance form for a porcelain fused to metal (PFM) crown should have a minimum height of 4mm, a maximum width of 10mm and a height-to-width ratio of at least 0.4. Aims and Objectives: To determine whether the molar crown preparations for full-coverage PFM crowns made by Resident dentists at the University of Ghana Dental School (UGDS) meet the recommended requirements for resistance form. Study design: This is a cross-sectional study to analyse the resistance form of molar crown preparation of patients scheduled for full-coverage PFM crown. Materials and Methods: This was a prospective study to analyse the height, width, and height-to-width ratio (some of the intrinsic factors of resistance form) of 77 molar crown preparations. The height, width, and height-to-width ratio of each molar die were determined using the Exocad software. A descriptive summary of the various heights, widths and height-to-width ratio were summarized as means and their standard deviations. Chi-square test was used to compare the acceptability levels of the variables with their respective recommended clinically acceptable values. Results: The mean height and mean width of all the molar dies were 3.3±0.8mm and 10.1±1.1mm respectively. The mean height-to-width ratio of all the molar dies was 0.3±0.1. Only 19.5% of the dies were able to achieve the recommended height, and 18.2% of the molar dies had a minimum height-to-width ratio of 0.4 which is required for molar crown preparation. Conclusion: The findings of this study did not meet most of the recommended clinically acceptable values of the resistance form of molar crown preparations. The authors recommend organising in-service training or continuous professional development for clinicians who lack the skills in crown preparation in order to perfect their skills to create acceptable prepared crowns with adequate resistance form and to conduct a longitudinal clinical study to assess the crown preparations and the longevity of their fabricated crowns.