Evaluation of resistance form for prepared teeth

Area of Science:

• Dental Materials Science
• Prosthodontics
• Biomechanical Engineering

Background:

• Dental restorations, particularly those involving castings, require adequate resistance form to ensure longevity and prevent dislodgement.
• The presence and placement of retentive features, such as grooves, can significantly influence the mechanical stability of dental preparations.

Purpose of the Study:

• To evaluate the resistance form of dental preparations intended for castings.
• To assess the impact of preparation design, specifically the inclusion of grooves, on resistance to dislodgement.

Main Methods:

• Resistance form was assessed on dental preparations for which castings were fabricated in a large dental laboratory.
• Evaluation involved applying finger pressure to uncemented castings on dies to test dislodgement in buccal, lingual, mesial, and distal directions.
• Preparations were categorized by tooth group: incisors, canines, premolars, and molars.

Main Results:

• Resistance form was observed in 96% of incisor preparations, 92% of canine preparations, 81% of premolar preparations, and only 46% of molar preparations.
• Out of 294 preparations, only nine featured grooves.
• Grooves, whether mesial/distal or buccal/lingual, enhanced resistance against dislodgement in opposing directions.

Conclusions:

• Molars exhibit a notably lower resistance form compared to other tooth groups, indicating a potential vulnerability in casting preparations for these teeth.
• The strategic placement of grooves is crucial for improving the resistance form of dental preparations, thereby enhancing retention and stability.
• Further research into optimizing preparation designs for molars may be warranted to improve clinical outcomes.