An In Vitro Comparative Assessment Of The Effectiveness Of Occlusal Convergence Reduction, Modification Of The Occlusal Surface, And Added Auxiliary Features On Full Veneer Metal Crown Resistance Placed On A Molar Tooth Having Inadequate Resistance Form

Abstract

Introduction: Owing to the inadequate resistance forms, fixed partial dentures and single crowns get dislodged. Hence, it is vital to assess tooth preparation features that can help in the prevention of these failures due to inadequate resistance form.

Aim: The present study was conducted to assess the effectiveness of occlusal convergence reduction, modification of the occlusal surface, and added auxiliary features on full veneer metal crown resistance placed on a molar tooth having inadequate resistance form.

Materials and Methods: In the present study, a tooth preparation in the ivorine molar of the mandibular arch was done with inadequate resistance form features including total occlusal convergence (TOC) of 20 and an axial wall height of 2.5mm. This was followed by the addition of seven auxiliary features one after the other including reduced TOC by 8° in cervical aspect, occlusal inclined planes, mesiodistal boxes, buccolingual grooves, buccolingual and mesiodistal grooves, mesiodistal grooves, and mesiodistal grooves added to 8° reduced TOC in the cervical aspect. For each group, 10 dies were prepared with their respective crowns. On the INSTRON testing, resistance testing of all the samples was done.

machine.

Results: Statistically significant greatest resistance was seen by modifying the over tapered die preparation by decreasing the TOC to 8° in the cervical 1.5mm of the axial wall with the subsequent addition of mesiodistal groove to the decreased cervical TOC leading to the highest resistance to the dislodgement.

Conclusion: The present study concludes that for a crown preparation that is over tapered, decreasing the total occlusal convergence in the cervical area to 8° and further adding the proximal groves results in maximum resistance form in the preparation.