Poliklinik für Zahnärztliche Prothetik

Direktor: Prof. Dr. Gerhard Handel


Material substitutes for human incisors in in-vitro fracture tests.

Rosentritt M.*, Behr M., Nowak A., Handel G.

(Department of Prosthetic Dentistry, University of Regensburg, Germany)

Introduction: To improve the validity of in-vitro fracture tests, identical dimensions of the tested specimens may be required. Therefore moldable metals or resins are used to substitute human teeth. The aim of this study was to examine the influence of various teeth substitutes on the fracture resistance of post and core restored incisors.

Materials and Methods: Incisors with identical dimensions were formed of CrCo, two veneering composites (Adoro, Ivoclar-Vicadent; Belleglass, Kerr), PMMA (Palapress), resin teeth (Frascao) or epoxy resin and embedded under 135°. A polyether layer covering the roots simulated the periodontium. Identical FRC-posts (Postec, Ivoclar-Vivadent), composite cores (Tetric Ceram) and crowns (CoCr or ceramic Empress2) were provided and adhesively fixed (Variolink2). Human incisors were used as a control group. For evaluating the influence of the crown material CrCo, human incisors and Adoro were crowned with ceramic (Empress2). 8 specimens of each group were stressed in an artificial mouth with thermal cycling and mechanical loading (TCML 6000x5°C/55°C, each 2min, 1.2*106 x 50N). After TCML the fracture resistance (v=1mm/min, 135°, Zwick 1446, G) and type of fracture were determined. Statistical analysis was performed using one-way-ANOVA (p=0.05).

Results: Specimens with ceramic crowns showed fracture values [N] of 434.5± 166.1 (human incisor), 167.6± 23.4 (Adoro) and 418.1±120.0 (CrCo).

X std [N]

Frasco

PMMA

Adoro

Belleglass

Epoxy

CoCr

CoCr crown

93.3107.9

0.00.0 (failure)

129.147.1

172.059.8

91.072.1

375.6146.8

Conclusion: Only restorations on CoCr-roots showed a fracture resistance comparable to crowns on human incisors, but different fracture pattern. Roots made of PMMA, resin, composite or epoxy are not usable to substitute human incisors in fracture tests.


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