A comparative study on the correlation between Korean foods and the fractures of PFG and all ceramic crowns for posterior applications / 대한치과보철학회지

ABSTRACT

STATEMENT OF PROBLEM: Recently, there have been increased esthetic needs for posterior dental restorations. The failure of posterior dental ceramic restoration are possible not only by the characters of the component materials but also by the type of food. PURPOSE: The research aim was to compare the in vitro fracture resistance of simulated first molar crowns fabricated using 4 dental ceramic systems, full-porcelain-occlusal-surfaced PFG, half-porcelain-occlusal-surfaced PFG, Empress 2, Ice Zirkon and selected Korean foods. MATERIAL AND METHODS: Eighty axisymmetric crowns of each system were fabricated to fit a preparation with 1.5- to 2.0-mm occlusal reduction. The center of the occlusal surface on each of 15 specimens per ceramic system was axially loaded to fracture in a Instron 4465, and the maximum load (N) was recorded. Afterwards, selected Korean foods specimens (boiled crab, boiled chicken with bone, boiled beef rib, dried squid, dried anchovy, round candy, walnut shell) were prepared. 15 specimens per each food were placed under the Instron and the maximum fracture loads for them were recorded. The 95% confidence intervals of the characteristic failure load were compared between dental eramic systems and Korean foods. Afterwards, on the basis of previous results, 14Hz cyclic load was applied on the 4 systems of dental ceramic restorations in MTS. The reults were analyzed by analysis of variance and Post Hoc tests. RESULTS: 95% confidence intervals for mean of fracture load 1. full porcelain occlusal surfaced PFG Crown 2599.3 to 2809.1 N 2. half porcelain occlusal surfaced PFG Crown 3689.4 to 3819.8 N 3. Ice Zirkon Crown 1501.2 to 1867.9 N 4. Empress 2 Crown 803.2 to 1188.5 N 5. boiled crab 294.1 to 367.9 N 6. boiled chicken with bone 357.1 to 408.6 N 7. boiled beef rib 4077.7 to 4356.0 N 8. dried squid 147.5 to 190.5 N 9. dried anchovy 35.6 to 46.5 N 10. round candy 1900.5 to 2615.8 N 11. walnut shell 85.7 to 373.1 N under cyclic load (14Hz) in MTS, fracture load and masticatory cycles are 1. full porcelain occlusal surfaced PFG Crown fractured at 95% confidence intervals of 4796.8 - 9321.2 cycles under 2224.8 N (round candy)load, no fracture under smaller loads. 2. half porcelain occlusal surfaced PFG Crown fractured at 95% confidence intervals of 881705.1 - 1143565.7 cycles under 2224.8 N (round candy). no fracture under smaller loads. 3. Ice Zirkon Crown fractured at 95% confidence intervlas of 979993.0 - 1145773.4 cycles under 382.9 N (boiled chicken with bone). no fracture under smaller loads. 4. Empress 2 Crown fractured at 95% confidence intervals of 564.1 - 954.7 cycles under 382.9 N (boiled chicken with bone). no fracture under smaller loads. CONCLUSION: There was a significant difference in fracture resistance between experimental groups. Under single load, Korean foods than can cause fracture to the dental ceramic restorations are boiled beef rib and round candy. Even if there is no fracture under single load, cyclic dynamic load can fracture dental posterior ceramic crowns. Experimental data with 14 Hz dynamic cyclic load are obtained as follows. 1. PFG crown (full porcelain occlusion) was failed after mean 0.03 years under fracture load for round candy (2224.8 N). 2. PFG crown(half porcelain occlusion) was failed after mean 4.1 years under fracture load for round candy (2224.8 N). 3. Ice Zirkon crown was failed after mean 4.3 years under fracture load for boiled chicken with bone (382.9 N). 4. Empress 2 crown was failed after mean 0.003 years under fracture load for boiled chicken with bone (382.9 N).