[Changes in retention strength of luting cements by repeated loading]

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Prosthodontics

Background:

• Dental crown retention is crucial for restoration longevity.
• Luting cements play a vital role in securing crowns to abutment teeth.
• Understanding cement behavior under functional loads is essential for clinical success.

Purpose of the Study:

• To evaluate the retention of dental crowns cemented with three luting agents under simulated occlusal loading.
• To compare the performance of glass ionomer, polycarboxylate, and zinc phosphate cements.
• To investigate the influence of water storage and repeated loading on cement retention strength.

Main Methods:

• Prepared Ni-Cr alloy crowns and abutment tooth models with sandblasted surfaces.
• Applied compressive loads (2.5-10.0 kg) 7,200 times daily for 1, 3, or 7 days.
• Assessed crown retention after cementation and simulated intraoral conditions.

Main Results:

• Polycarboxylate and zinc phosphate cements demonstrated significantly higher crown retention than glass ionomer cements.
• Glass ionomer cement retention increased with 7-day water storage but decreased with repeated loading.
• Polycarboxylate and zinc phosphate cements showed decreased retention after 3 days of water storage, yet maintained or improved retention with 7 days of repeated loading.

Conclusions:

• Polycarboxylate and zinc phosphate cements provide more durable crown retention under functional stress than glass ionomer cements.
• The choice of luting cement impacts restoration stability, especially in the presence of moisture and mechanical forces.
• Clinical recommendations should consider cement type for long-term crown success.