Reporting numeric values of complete crowns. Part 1: Clinical preparation parameters

Area of Science:

• Dental Materials Science
• Restorative Dentistry
• Clinical Measurement

Background:

• No objective system currently exists for measuring clinical tooth preparations.
• Evaluating the accuracy of clinical tooth preparations is crucial for restoration success.

Purpose of the Study:

• To objectively compare clinical tooth preparations for ceramic crowns against established literature values.
• To assess the conformity of general dentists' preparations using a novel measurement method.

Main Methods:

• Analyzed 236 stone dies for ceramic crown restorations using coordinate geometry.
• Measured total occlusal convergence angle, margin width, and abutment height via cross-sectioned images.
• Utilized objective measurement techniques for precise data acquisition.

Main Results:

• Average total occlusal convergence angles exceeded recommended values for all tooth types.
• Average margin widths were below the minimum recommended range (0.40-0.83 mm vs. 1-1.5 mm).
• Abutment height varied, with maxillary canines being tallest (5.25 mm) and mandibular molars shortest (1.87 mm).

Conclusions:

• Clinical complete crown preparations in general practice do not meet literature-based recommendations.
• Current literature recommendations lack clinical trial validation.
• The impact of observed preparation discrepancies on restoration longevity remains unpredictable.