Bonfante Gerson, Kaizer Osvaldo Bazzan, Pegoraro Luiz Fernando, do Valle Accácio Lins
Department of Prosthodontics, Bauru Dental School, University of São Paulo.
J Appl Oral Sci. 2006 Aug;14(4):247-52. doi: 10.1590/s1678-77572006000400007.
This study investigated the compressive fracture strength and failure pattern in premolars submitted to endodontic treatment and internal bleaching with 37% carbamide peroxide for 21 days, with application of different restorative procedures.
Six groups were employed (n = 10): 1) non-bleached teeth and pulp chamber sealed with IRM; 2) bleached teeth and pulp chamber sealed with IRM; 3) bleached teeth and pulp chamber filled with light cured composite resin; 4) bleached teeth, root canals prepared at 10mm, filling of the root canal and pulp chamber with IRM; 5) bleached teeth, root canals prepared at 10mm, luting of prefabricated metallic post with zinc phosphate and pulp chamber sealed with composite resin; 6) bleached teeth, root canals prepared at 10mm, luting of glass fiber post with resin cement and pulp chamber sealed with composite resin. After 24-hour storage in distilled water, the specimens were submitted to compressive fracture strength testing in a universal testing machine.
The following values were found: Group 1 - 56.23kgf; Group 2 - 48.96kgf; Group 3 - 53.99kgf; Group 4 - 45.72kgf; Group 5 - 54.22kgf; Group 6 - 60.12kgf. The analysis of variance did not reveal statistically significant difference between groups (p<0.05), suggesting that internal bleaching with 37% carbamide peroxide did not weaken the dental tissues. The largest number of unfavorable fractures was observed for Groups 2 (50%), 4 (40%), and 5 (30%). Group 6 exhibited the most favorable failure pattern.
The results suggest that internal bleaching with 37% carbamide peroxide did not significantly weaken the teeth. Among the bleached teeth, those with temporary IRM restorations or metallic posts demonstrated the most unfavorable fracture pattern, whereas the most favorable fracture pattern occurred in teeth restored with composite resin and glass fiber posts.
本研究调查了经根管治疗并用37%过氧化脲进行21天内漂白处理后，采用不同修复程序的前磨牙的抗压骨折强度和失效模式。
采用六组（n = 10）：1）未漂白牙齿，牙髓腔用IRM封闭；2）漂白牙齿，牙髓腔用IRM封闭；3）漂白牙齿，牙髓腔用光固化复合树脂填充；4）漂白牙齿，根管预备至10mm，根管和牙髓腔用IRM填充；5）漂白牙齿，根管预备至10mm，用磷酸锌水门汀粘结预制金属桩，牙髓腔用复合树脂封闭；6）漂白牙齿，根管预备至10mm，用树脂水门汀粘结玻璃纤维桩，牙髓腔用复合树脂封闭。在蒸馏水中储存24小时后，将标本在万能试验机上进行抗压骨折强度测试。
得到以下数值：第1组 - 56.23千克力；第2组 - 48.96千克力；第3组 - 53.99千克力；第4组 - 45.72千克力；第5组 - 54.22千克力；第6组 - 60.12千克力。方差分析未显示组间有统计学显著差异（p<0.05），表明用37%过氧化脲进行内漂白不会削弱牙体组织。第2组（50%）、第4组（40%）和第5组（30%）观察到的不利骨折数量最多。第6组表现出最有利的失效模式。
结果表明，用37%过氧化脲进行内漂白不会显著削弱牙齿。在漂白牙齿中，采用临时IRM修复或金属桩的牙齿表现出最不利的骨折模式，而采用复合树脂和玻璃纤维桩修复的牙齿出现最有利的骨折模式。
