Effective application duration of sodium ascorbate antioxidant in reducing microleakage of bonded composite restoration in intracoronally-bleached teeth

OBJECTIVES: The aim of this study was to determine an appropriate application duration of sodium ascorbate (SA) antioxidant gel in reducing microleakage of bonded composite restoration in intracoronally-bleached teeth. MATERIALS AND METHODS: Eighty endodontically-treated human incisors were randomly divided into eight groups: control, no bleaching; IB and DB, immediate and delayed bonding after bleaching, respectively; S10m, S60m, S24h, S3d and S7d, bleaching + SA gel for 10 min, 60 min, 24 hr, 3 day and 7 day, respectively. For bleaching, a mixture of 30% hydrogen peroxide and sodium perborate was applied for 7 day. All access cavities were restored using One-Step adhesive (Bisco Inc.) and then Aelite LS Packable composite (Bisco Inc.). The bonded specimens were subjected to 500 thermal cycles, immersed in 1% methylene blue for 8 hr, and longitudinally sectioned. Microleakage was assessed with a 0 - 4 scoring system and analyzed using nonparametric statistical methods (alpha = 0.05). RESULTS: Group IB showed a significantly higher microleakge than the control group (p = 0.006) and group DB a statistically similar score to the control group (p > 0.999). Although groups S10m, S60m, and S24h exhibited significantly higher scores than group DB (p 0.999). CONCLUSIONS: Application of SA gel for 3 day after nonvital bleaching was effective in reducing microleakage of composite restoration in intracoronally-bleached teeth.

Invasive cervical resorption: treatment challenges

Invasive cervical resorption is a relatively uncommon form of external root resorption. It is characterized by invasion of cervical region of the root by fibrovascular tissue derived from the periodontal ligament. This case presents an invasive cervical resorption occurring in maxillary lateral incisor, following damage in cervical cementum from avulsion and intracoronal bleaching procedure. Flap reflection, debridement and restoration with glass ionomer cement were performed in an attempt to repair the defect. But after 2 mon, more resorption extended apically. Considering root stability and recurrence potential, we decided to extract the tooth. Invasive cervical resorption in advanced stages may present great challenges for clinicians. Therefore, prevention and early detection must be stressed when dealing with patients presenting history of potential predisposing factors.

Sealing ability of MTA used as cervical barrier in intracoronal bleaching

The aim of this study was to compare the sealing ability of white mineral trioxide aggregate (MTA) with that of other materials used as a cervical barrier during intracoronal bleaching. Thirty eight extracted teeth were endodontically treated and 3 mm of filling was removed to receive the barrier material: G1- Coltosol; G2 - Vidrion R; G3 - White MTA; G4-No barrier (negative control) and G5- Roots totally protected with three layers of cyanoacrylate (positive control). The 30% hydrogen peroxide associated with the sodium perborate was left in the pulp chamber for 24 h. The specimens were immersed in a test tube containing a solution of potassium chromate (yellow), which turns blue in the presence of hydrogen peroxide. Two calibrated evaluators scored according to color in the presence of the detecting solution (0 - unaltered color, 1 - light blue and 2 - dark blue). Data were analyzed by the Kruskall-Wallis test (p<0.05). The results showed no statistically significant differences between the experimental group G3 and positive control (G5). No statistically significant difference was observed between G1 and G3. However, a statistical difference was verified between G2 and G3. MTA presented higher sealing ability than Vidrion R and did not differ from the positive control. However, there was no difference between MTA and Coltosol.

O objetivo deste estudo foi comparar a capacidade de selamento do agregado trioxido mineral (MTA) branco com outros materiais usados como barreiras cervicais durante clareamento intra-coronario. Trinta e oito dentes extraidos foram endodonticamente tratados e 3 mm de obturacao foi removida para receber o material da barreira: G1- Coltosol; G2 - Vidrion R; G3 - MTA branco; G4-Nenhuma barreira (controle negativo) e G5- Raizes totalmente protegidas com tres camadas de cianocrilato (controle positivo). Peroxido de hidrogenio a 30% (PH) associado com perborato de sodio foi deixado na camara pulpar por 24 h. As amostras foram imersas em tubos de ensaio contendo uma solucao de cromato de potassio (amarela) que se torna azul na presenca de peroxido de hidrogenio. Dois avaliadores calibrados atribuiram escores de acordo com a cor obtida na solucao detectora (0 - cor inalterada, 1 - azul claro e 2 - azul escuro). Os dados foram analisados pelo teste de Kruskall-Wallis (p<0,05). Os resultados nao mostraram diferencas estatisticamente significantes entre o grupo experimental G3 e o controle positivo (G5). Nenhuma diferenca estatisticamente significante foi observada entre G1 e G3. Entretanto, diferenca estatistica foi verificada entre G2 e G3. MTA apresentou maior habilidade de selamento que o Vidrion R e nao diferiu do controle positivo. Entretanto, nao houve diferenca entre MTA e Cotosol.

In vitro evaluation of extraradicular diffusion of 6% hydrogen peroxide during intracoronal bleaching / Avaliação in vitro da difusão extra-radicular do peróxido de hidrogênio a 6% durante clareamento coronário interno

Purpose: To evaluate the extraradicular diffusion of creamy 6 % hydrogen peroxide (HP) associated or not with sodium perborate (SP) at the cervical region of endodontically treated teeth during intracoronal bleaching. Methods: Thirty-two endodontically treated maxillary canines and central incisors were used. The gutta-percha was removed 3 mm below the cement/enamel junction, and the external root surface was covered with cyanoacrylate except for the cervical region. The teeth were randomly allocated to 4 groups: G1: 6 % HP+SP (n=11); G2: 6 % HP (n=11); G3: distilled water (negative control, n=5) and G4: 30 % HP (positive control, n=5). The specimens were immersed in a solution of potassium chromate (yellow), which turns blue in presence of HP. Two calibrated examiners (Kendall coefficient = 0.936) attributed scores according to the solution color (0 - unaltered color, 1 - light blue, and 2 - dark blue). Data were analyzed by Kruskal-Wallis and Mann-Whitney tests (α<0.05). Results: Eighteen percent of the 6 % HP specimens with or without SP showed color alteration. Only G4 had score values statistically higher than the other groups (P=0.004). Conclusion: It can be concluded that 6 % HP cream did not have significant extraradicular diffusion during intracoronal bleaching but it was not 100 % safe.

Objetivo: Avaliar a difusão do peróxido de hidrogênio (PH) 6 % em creme, associado ou não ao perborato de sódio (PS) na região cervical de dentes endodonticamente tratados durante clareamento coronário interno. Metodologia: Foram utilizados 32 caninos e incisivos superiores tratados endodonticamente. Removeu-se 3mm de guta-percha abaixo da junção cemento/esmalte e a superfície radicular externa foi impermeabilizada com cianoacrilato, exceto a região cervical. Os dentes foram divididos aleatoriamente em: G1: PH 6 %+PS (n=11); G2: PH 6 % (n=11); G3: águadestilada (controle negativo, n=5) e G4: PH 30 % (controle positivo, n=5). Os espécimes foram imersos em solução de cromato de potássio (cor amarela), que se torna azul na presença do PH. Dois avaliadores calibrados (coeficiente de Kendall = 0,936) atribuíram escores de acordo com a cor da solução evidenciadora (0 - cor inalterada; 1 - azul claro e 2 - azul escuro). Os dados foram analisados pelos testes de Kruskal-Wallis e Mann-Whitney (α=0,05). Resultados: Em 18% dos casos houve difusão extra-radicular do PH 6%, estando este associado ou não ao perborato de sódio. Apenas o G4 apresentou valores estatisticamente maiores que os demais (P=0,004). Conclusão: Pode-se concluir que o PH 6 % em creme não apresentou difusão extra-radicular significativa durante o clareamento coronário interno, mas não foi 100 % seguro.