Effect of Posterior Veneer Preparation Design on Failure Load and Mode Before and After Fatigue

Articles in Press

Document Type : Original Article

Authors

1 Master Degree Student, Department of Operative Dentistry, Faculty of Dentistry Alexandria University, Egypt.

2 biomaterials department alexandria university

3 Operative Dentistry, Conservative Dentistry Department, Faculty of Dentistry, Alexandria University.

4 Lecturer of Conservative Dentistry, Department Conservative Dentistry, Faculty of Dentistry Alexandria University.

Abstract

Introduction: Ceramic veneers play a vital role in dental aesthetics, providing accurate and efficient restoration of tooth shape, color, contour, and the function. The preparation design is a crucial determinant for the veneer success, as it significantly affects their resistance to failure and overall longevity, especially in minimally invasive for posterior teeth ceramic restorations.

Objectives: To evaluate the buccal cusp reduction and mesio-occluso-distal (MOD) box preparation designs effect on the fatigue survival and the failure load of minimally invasive posterior ceramic veneer restorations.

Materials and methods: Twenty human maxillary premolars were assigned into two groups each of ten. Control group with intact unprepared premolars. Study group: premolars were prepared with a depth of 0.7 mm for buccal preparation, buccal cusp reduction, and MOD box preparation. Restorations with Monolithic lithium disilicate were adhesively cemented then subjected to cyclic mechanical loading and thermocycling simultaneously. All specimens were exposed to “single load-to-failure”. The difference between failure load before and after fatigue was calculated, and stress at failure was calculated using fractography.

Results: The Fracture Resistance shows no notable difference between the two groups examined, both prior to and following fatigue testing. Nonetheless, the reduction in fracture resistance percentage was statistically significantly less in the MOD group compared to the control group. In the MOD group the main failure mode was type II, accounting for 60% of the specimens.

Conclusion: Preparation designs with minimally invasive non-retentive with MOD demonstrated satisfactory fatigue and fracture resistance, supporting the need for further clinical research.

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Alexandria Dental Journal

Articles in Press, Accepted Manuscript
Available Online from 06 October 2025

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