| 1260 Fracture Strengths of Molars Depending on Defect Size and Restoration | ||
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P. SCHMAGE, M. KOBA, I. NERGIZ, and U. PLATZER, University of Hamburg, Dental School, Germany Objectives: Crown-fractures of posterior teeth are well known problems in Operative Dentistry and depend on the cavity size and the restoration material. The restoration of the destructed tooth structure is expected to offer the same functioning and strength compared to the previously sound tooth. This study aimed to investigate the effects of cavities and restoration materials on the fracture strengths and fracture modalities of molars. Methods: 350 extracted molars (n=50) were prepared with mod-cavities (MOD) or with mod- and root canal access-cavities (MOD+A) of defined dimensions. The fillings were performed using one glass ionomer cement (GIC)(Ketac Molar, ESPE, Seefeld, Germany) and two composites (DU and RE)(Durafill, Heraeus-Kulzer, Dormagen, Germany; Rebilda, Voco, Cuxhaven, Germany). The following seven groups were formed: MOD and MOD+A both without fillings and with GIC, MOD+A with DU and RE respectively; sound molars were used for control. The fracture strengths of the teeth were measured using a tensile force test (Instron 1026, Mass., USA). The results were analyzed statistically using the ANOVA-test and the Scheffé-correction. Results: Sound molars had the highest fracture strengths (2694Nħ910N). Significant differences were found between MOD without filling (1220Nħ295N) and with GIC (2525Nħ829N) as well as between MOD+A without filling (581Nħ146N) and with filling. No significant differences occured between the used restoration materials in MOD+A (GIC 1600Nħ421N, DU 1398Nħ448N, RE 1360Nħ503N). Relevant factors to differentiate the investigated teeth were upper or lower molars, first, second or third molars and the occlusal surface area. In most cases one of the cuspids was fractured, the use of composites for core built-up could avoid vertical fractures. Conclusions: The strengths of the molars decreased significantly with the cavity size and could not be totally reinforced with a filling, but the stabilization was not effected significantly by the restoration material. | ||
| Seq #123 - Properties of Polymers and Tooth Structure 3:45 PM-5:00 PM, Thursday, 7 March 2002 San Diego Convention Center Exhibit Hall C | ||
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