Randomized Two-year Clinical Evaluation of Oxalic Acid in Restorations of Noncarious Cervical Lesions.

PURPOSE: To evaluate the use of oxalic acid in restorations of noncarious cervical lesions. MATERIALS AND METHODS: Twenty volunteers of both sexes between 24 and 55 years old, with at least two lesions that were restored with the techniques to be evaluated, were selected. Ninety teeth were randomly divided into two groups: group 1, two-step etch-and-rinse adhesive technique (control) and group 2, pretreatment with oxalic acid followed by the application of a two-step etch-and-rinse adhesive system. The adhesive system used was XP Bond (Dentsply) and the restorative composite resin was Durafill (Heraeus Kulzer). A modified USPHS method was employed for the clinical evaluation, taking into account the following criteria: retention (R), marginal integrity (MI), marginal discoloration (MD), postoperative sensitivity (S), caries (C), and anatomic form (AF). Clinical assessments were conducted by two examiners at baseline and after 6 months, 1 and 2 years. RESULTS: After two years, the results of clinically satisfactory restorations (Alpha and Bravo) obtained for the control and experimental groups were: R (90.9%/93.33%), MI (100%/100%), MD (100%/100%), S (100%/100%), C (100%/100%), AF (100%/100%). CONCLUSION: Over a 2-year period, the use of oxalic acid as an agent of dentin pretreatment did not influence the clinical performance of restorations in noncarious cervical lesions.

Four-year randomized clinical trial of oxalic acid pretreatment in restorations of non-carious cervical lesions.

OBJECTIVE: The aim of this study was to evaluate the efficiency of oxalic acid (BisBlock) on restorations of non-carious cervical lesions. MATERIALS AND METHODS: One operator placed 90 restorations randomly divided into two groups in 20 patients under cotton rolls isolation: Control Group-two-step etch-and-rinse adhesive technique; and Experimental Group-two-step etch-and-rinse adhesive technique with oxalic acid pretreatment after acid-etched dentin. The restorative adhesive system used was XP Bond/Durafill. The restorations were directly assessed by two independent examiners, using the modified United States Public Health Service (USPHS) criteria at the baseline and 4 years. Data were statistically analyzed using the Fisher and McNemar tests (p < 0.05). RESULTS: Fifteen patients (75%) were available for recall after 4 years. The McNemar test detected significant differences within the Experimental Group between the baseline and 4-year evaluations for retention (p < 0.05). For the Control Group, there was no significant difference (p > 0.05) between the periods. The Fisher test showed no statistically significant difference between the groups for all other criteria (p > 0.05). CONCLUSION: After 4 years of service, the use of oxalic acid did not influence the clinical performance of restorations when it was used under composite resin restorations.

Surface treatments for repair of feldspathic, leucite - and lithium disilicate-reinforced glass ceramics using composite resin.

The aim of this study was to evaluate the efficacy of different surface conditioning methods on the microtensile bond strength of a restorative composite repair in three types of dental ceramics: lithium disilicate-reinforced, leucite-reinforced and feldspathic. Twelve blocks were sintered for each type of ceramic (n=3) and stored for 3 months in distilled water at 37 °C. The bonding surface of ceramics was abraded with 600-grit SiC paper. Surface treatments for each ceramic were: GC (control) - none; GDB - diamond bur #30 µm; GHF - hydrofluoric acid (10%); GT- tribochemical silica coating (45-µm size particles). Treatments were followed by cleaning with phosphoric acid 37% for 20 s + silane + adhesive. The composite resin was used as restorative material. After repair, samples were subjected to thermocycled ageing (10,000 cycles between 5 °C and 55 °C for 30 s). Thereafter, the samples were sectioned into 1.0 mm2 sticks and tested for microtensile bond strength with 0.5 mm/min crosshead speed. Data were compared by two-way ANOVA and Tukey's test (α=0.05). The superficial wear with diamond bur proved to be suitable for feldspathic porcelain and for leucite-reinforced glass ceramic while hydrofluoric acid-etching is indicated for repairs in lithium disilicate-reinforced ceramic; tribochemical silica coating is applicable to leucite-reinforced ceramic. Predominance of adhesive failures was observed (>85% in all groups). In conclusion, the success of surface treatments depends on the type of ceramic to be repaired.

Surface Treatments for Repair of Feldspathic, Leucite - and Lithium Disilicate-Reinforced Glass Ceramics Using Composite Resin

The aim of this study was to evaluate the efficacy of different surface conditioning methods on the microtensile bond strength of a restorative composite repair in three types of dental ceramics: lithium disilicate-reinforced, leucite-reinforced and feldspathic. Twelve blocks were sintered for each type of ceramic (n=3) and stored for 3 months in distilled water at 37 °C. The bonding surface of ceramics was abraded with 600-grit SiC paper. Surface treatments for each ceramic were: GC (control) - none; GDB - diamond bur #30 µm; GHF - hydrofluoric acid (10%); GT- tribochemical silica coating (45-μm size particles). Treatments were followed by cleaning with phosphoric acid 37% for 20 s + silane + adhesive. The composite resin was used as restorative material. After repair, samples were subjected to thermocycled ageing (10,000 cycles between 5 °C and 55 °C for 30 s). Thereafter, the samples were sectioned into 1.0 mm2 sticks and tested for microtensile bond strength with 0.5 mm/min crosshead speed. Data were compared by two-way ANOVA and Tukey's test (α=0.05). The superficial wear with diamond bur proved to be suitable for feldspathic porcelain and for leucite-reinforced glass ceramic while hydrofluoric acid-etching is indicated for repairs in lithium disilicate-reinforced ceramic; tribochemical silica coating is applicable to leucite-reinforced ceramic. Predominance of adhesive failures was observed (>85% in all groups). In conclusion, the success of surface treatments depends on the type of ceramic to be repaired.

O objetivo deste estudo foi avaliar a eficácia de diferentes condicionamentos de superfície na resistência de união de reparos de compósitos restauradores em três tipos de cerâmicas odontológicas: reforçada por dissilicato de lítio, reforçada por leucita e feldspática. Foram confeccionados 12 blocos para cada tipo de cerâmica (n=3) e armazenados por 3 meses em água destilada a 37 oC. A superfície de união das cerâmicas foi regularizada com lixa de granulação 600 por 15 s e lavadas em ultrassom por 10 min. Os tratamentos de superfície para cada cerâmica foram: GC (controle) - nenhum; GPD - ponta diamantada com 30 µm de granulação; GAF - ácido hidrofluorídrico a 10%; GJ - jateamento com partículas de óxido de alumínio revestido por sílica (45 µm - tamanho das partículas). Após, foi realizada a limpeza da superfície com ácido fosfórico a 7% por 20 s, seguido de silano e adesivo. Como material restaurador foi utilizada resina composta. Após o reparo, as amostras foram submetidas a ciclagem térmica (10,000 ciclos entre 5 °C e 55 °C, por 30 s). Na sequência, as amostras foram seccionadas em palitos de aproximadamente 1,0 mm2 e levadas ao teste de tração em uma máquina de ensaios universal à velocidade de 0,5 mm/min. Os dados obtidos foram comparados estatisticamente por ANOVA de dois fatores e teste de Tukey (α=0,05). Sugere-se que o desgaste da superfície com ponta diamantada é mais indicado para a cerâmica feldspática e cerâmica reforçada por leucita, enquanto o condicionamento com ácido fluorídrico é indicado para reparos em cerâmica reforçada por dissilicato de lítio. O jateamento com partículas de óxido de alumínio revestido por sílica mostrou-se aplicável à cerâmica reforçada por leucita. Predominancia de fraturas adesivas acima de 85% foi observada para todos os grupos. Este estudo demonstrou que o sucesso dos tratamentos de superfície depende do tipo de cerâmica a que são aplicados.