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Quasistatic Mechanical Testing for Computer-Aided Design and Manufacturing Occlusal Veneers Cemented to Milled Dentin Analog Material
Published on: December 20, 2024
All-ceramic partial coverage premolar restorations. Cavity preparation design, reliability and fracture resistance
Christian F J Stappert1, Petra C Guess, Thomas Gerds
1Department of Prosthodontics, School of Dentistry, Albert-Ludwigs-University, Hugstetter Str. 55, 79106 Freiburg, Germany. stappert@zmk2.ukl.uni-freiburg.de
Purpose:
To investigate the effects of different cavity preparation designs on the reliability and fracture resistance of partial coverage restorations (PCR) which were luted adhesively to natural premolars after exposure to a mastication simulator.
Methods:
80 caries-free, extracted human maxillary premolars were randomly divided into two control groups (A, B) and three test groups (C-E) consisting of 16 specimens each. Group A served as a control group with no preparation. The specimens of Groups B to E were prepared as follows: Group B: MOD inlay, Group C: PCR (palatal), Group D: PCR (palatal and buccal), Group E: complete veneer. Using pressed ceramic IPS e.max Press (VP 1989), 64 all-ceramic restorations were fabricated and luted adhesively. The 80 specimens were subjected to 1.2 million mastication (F= 49 N) and 5500 thermal cycles at 5 degrees C and 55 degrees C in a mastication simulator. Subsequently, all test specimens were loaded occlusally until fracture using a universal testing machine. The statistical analysis included the unpaired Wilcoxon rank sum test and box plots.
Results:
All the specimens withstood the masticatory simulation. The following mean fracture strength values (N) (minimum/maximum) were recorded: Group A: 1446 (417/2404), Group B: 1351 (657/2096), Group C: 837 (346/1472), Group D: 963 (481/1691), Group E: 1361 (900/2211). The fracture strength values of Groups A, B and E were statistically significantly higher (P < 0.05) than those of Groups C and D. Inlays and complete veneers made of IPS e.max Press reached fracture strength values corresponding to those of natural premolars.
