The Causes of Marginal Discrepancy of Fixed Dental Prostheses: A Cross-Sectional Study

Abstract

Periodontal destruction observed in restored teeth is strongly caused by marginal discrepancy of the restoration, which is closely
influenced by the tooth preparation, the technique of retraction and impression.
Materials and Methods
A hundred practitioners were selected to constitute the study’s sample. A self-administered questionnaire survey was carried out.
The questionnaire was filled in the practitioner's office, completed in the absence of the investigator. However, it has been completed
for some clarifications by an interview. A digital form made through the Google Forms application provided free by the
Google search engine. The questionnaire included two sections: The identification of the practitioner: this is general information
about the practitioner. The conduct of prosthetic treatment. The causes of marginal discrepancy: This section concerns the major
factors responsible for a good marginal fit. The collected data was introduced and processed by the microcomputer using the
statistical software XLSTAT 2015 for Windows. A simple statistical analysis made it possible to calculate the percentage of the
different variables, from their frequency.
Results
There is a significant correlation between marginal discrepancy and the respect of the finish line geometry (p=0.001). The technique
of retraction which provided the best marginal fit was the use of expasyl paste (p=0.18). There was a significant association
between marginal discrepancy and the material of impression, marginal adaptation is found in 76% for impressions made by
alginate, 45% for impressions made by silicone, and 100% for impressions made by polysulphides (p=0.01).
Conclusion
Within limitations of this study, it can be concluded that the respect of guidelines of preparation especially the finish line and the
good choice of the retraction technique and the material of impression are the major keys to have a good marginal fit.