Fracture resistance and failure pattern of teeth submitted to internal bleaching with 37% carbamide peroxide, with application of different restorative procedures

Abstract

Objective.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.Material and methods.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.Results.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.Conclusions.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.

Fracture Resistance of Endodontically-treated Teeth: Effect of Combination Bleaching and an Antioxidant

“…9 In the current study, a potential chemical, Day White ACP (Discus Dental), with 9.5% hydrogen peroxide, was used for the at-home technique. As a result, contrary to a similar study, 19 in the current study, the coronal weakening of root-filled teeth occurred and the results obtained for Group II showed decreases in fracture resistance when compared with the negative control group (p<0.001).…”

“…This finding is consistent with the results of similar studies. 19,32 Furthermore, bleaching significantly decreased fracture resistance in Group II when compared to Group I (p<0.001), which concurs with the results of a study carried out by Pobbe and others; 2 however, the results of the current study are not consistent with results obtained by Chng and others. 33 This discrepancy might be attributed to the application of different bleaching techniques and different bleaching regimens in the above-mentioned studies.…”

“…Bonfante and others reported that the fracture resistance of endodonticallytreated teeth is not affected by bleaching with 37% carbamide peroxide after 21 days. 19 On the other hand, in a recent study, Pobbe and others showed that the fracture resistance of endodontically-treated teeth decreases after two sessions of bleaching with 38% hydrogen peroxide activated by a LED-laser system. 2 The compromise of bond strength due to bleaching procedures has been attributed to the residual free radicals of oxygen released from the whitening agent.…”

Influence of the Number of Bleaching Sessions on Fracture Resistance and Dentin Microhardness of Endodontically Treated Teeth

“…After endodontically treated dental bleaching, 37% carbamide peroxide does not affect the crown fracture resistance. 8 On the contrary, this resistance is affected negatively by hydrogen peroxide. 9 Dental bleaching substances effects are based an oxireduction reaction, and this process depends on the local pH, presence of metal particles, temperature, and light activation.…”

Effect of different restorative procedures on the fracture resistance of teeth submitted to internal bleaching

“…2,4 The use of composite resins with intraradicular posts has been recommended by some authors for restoring endodontically treated teeth submitted to dental bleaching, 11,12 mainly owing to their ability to increase the fracture resistance of these teeth, whereas other authors claim that intraradicular posts should be recommended only when there is loss of more than half of the dental crown, for the purpose of connecting the prosthetic crown to the remaining root structure, or when intense occlusal forces are at play. 13,14 Few studies have investigated different restorative procedures to minimize the damage caused by the loss of dental tissue resulting from endodontic treatment, on one hand, and by the changes in dental structure resulting from dental bleaching, on the other.…”