Technical failure rates of double crown-retained removable partial dentures

Area of Science:

• Prosthodontics
• Dental Materials Science
• Clinical Dentistry

Background:

• Removable partial dentures (RPD) are crucial for restoring oral function and aesthetics.
• Retainer systems, specifically double crowns (conical and parallel-sided), significantly influence RPD longevity and performance.
• Understanding the technical failure rates of different double crown systems is essential for improving prosthetic treatment outcomes.

Purpose of the Study:

• To evaluate and compare the technical failure rates of conical versus parallel-sided telescopic double crown retainer systems for RPDs.
• To identify the types and frequencies of technical failures associated with each retainer system.

Main Methods:

• A retrospective analysis of 117 RPDs fabricated by dental school dentists.
• RPDs were categorized based on retainer system: 74 with parallel-sided crowns and 43 with conical crowns.
• Technical failures were documented and analyzed through medical report follow-ups from January 1992 to December 1998.

Main Results:

• Technical failures occurred in 48.8% of conical crown-retained RPDs and 34.2% of parallel-sided crown-retained RPDs.
• Loss of cementation was the most common failure for both systems.
• Loss of facings was exclusively observed in conical crown systems; denture base issues (fractured teeth, framework) were common across both.

Conclusions:

• Both double crown retainer systems exhibit distinct technical failure patterns.
• Parallel-sided double crowns demonstrate a lower technical failure rate compared to conical crowns.
• While failures are not insignificant, they are generally treatable, highlighting the need for careful material selection and maintenance.