An In Vitro Study to Compare and Evaluate the Preparation Details of Three Different Tooth Preparation Techniques for Metal Ceramic Crown

Abstract

Introduction: Tooth preparation for metal ceramic crowns must allow for an adequate thickness of metal and porcelain to overcome the limitations of each material as well as preserve the integrity of the pulp.
Excessive reduction can cause sensitivity and pulpal exposure which may necessitate a root canal treatment. In anterior teeth, a minimal incisal reduction of 2 mm is recommended to prevent an excessively long crown or a blunt incisal table. Hence, a successful porcelain fused to metal restoration is mainly dependent on an adequate tooth preparation. Under preparation may result in inappropriate labial and palatal contours, leading to poor esthetics. Over preparation can compromise tooth vitality.
The use of indices or suitable depth gauge burs are the two recognized methods of accurate tooth preparation; however, no study to date has investigates the effect of these two guides vis a vis free hand preparation.
Methodology:
Forty five maxillary left central incisor typodont teeth used in the study were allocated to 3 equal groups as Group A (n=15) : Teeth prepared with free hand approach, Group B(n=15): Teeth prepared using silicon putty index as guide, Group C(n=15) : Teeth prepared with the use of depth gauge burs. Silicon putty replica index made were used for evaluation. The index was sectioned axially along the midline of the prepared tooth and an optical microscope was used for evaluation of the dimensions.
Result:
This study found that under preparation of the labial aspect of teeth occurred when a freehand approach was adopted for the preparation of teeth to receive metal ceramic crowns ,Labial and incisal reduction was found to be accurate and consistent when teeth were prepared with the aid of depth gauge burs and silicone indices .
Conclusion: Whenever the clinical situation permits considerable importance should be given to the use of putty index and depth gauge burs.