Influence of early mineral deposits of silicate- and aluminate-based cements on push-out bond strength to root dentine.

AIM: To evaluate mineral trioxide aggregate (MTA), Biodentine and several formulations of calcium aluminate cements (CACb) in terms of their ability to release calcium ions (Ca2+ ) and form apatite-like precipitates after short-term immersion in phosphate-buffered saline (PBS) and its influence on the bond strength to the root-end cavity. METHODOLOGY: Ten samples of MTA, Biodentine, CACb and calcium-enriched aluminate cement (CACb+) were placed in contact with PBS or deionized water for 14 days. The cement surfaces were analysed using SEM, EDS-X and FTIR. Eighty standardized root-end cavities filled with the cements (ten samples of each cement) were immersed in PBS or deionized water for 14 days, and the bond strengths were measured. Data from the push-out test were analysed using two-way ANOVA and Tukey's tests (α = 0.05). RESULTS: A gradual decrease was observed in Ca2+ concentrations and pH of all solutions. FTIR bands of different phases of hydroxyapatite were identified. Crystalline formation was observed on the surface of all cements after immersion in PBS. No significant difference was observed in the bond strength of the test materials (P > 0.05); however, all cements without contact with the solution revealed significantly lower bond strength values than those in contact with the solution (P < 0.05). CONCLUSION: MTA, Biodentine, CACb e CACb+ were associated with precipitation of crystals after being in contact with PBS for 14 days, indicated by different phases of hydroxyapatite crystalline formation, which also increased dislodgment resistance of the material from root-end cavities. The CACb+ had similar bond strengths and precipitation of crystals to existing materials.

Avaliação de cavidades apicais realizadas com pontas ultrassônicas lisas, diamantadas e combinação de ambas / Evaluation of apical cavity preparation with ultrasonic, stainless steel, diamond coated lips and both

OBJETIVO: O objetivo deste trabalho foi avaliar, por meio do microscópio clínico e eletrônico devarredura, as paredes de cavidades apicais, as irregularidades produzidas com as pontas ultrassônicas diamantadas,lisas e com a combinação de ambas. MATERIAL E MÉTODO: Dezoito dentes pré-molaresinferiores de humanos, com apenas um conduto, foram apicetomizados e, no ápice, foram realizadascavidades para obturação retrógrada divididas em três grupos: grupo 1: cavidades preparadas com pontaultrassônica lisa; grupo 2: cavidades preparadas com ponta ultrassônica diamantada e grupo 3: cavidadespreparadas, iniciando com a ponta diamantada e seguida pela lisa. As paredes das cavidades foramobservadas inicialmente sob microscópio clínico e, a seguir, os ápice foram seccionados, metalizados eanalisados no microscópio eletrônico de varredura, atribuindo-se-lhes os seguintes escores: 1 - adequada;2 - regulares e 3 - irregulares. RESULTADOS: A ponta diamantada produziu 3 cavidades adequadas, 2regulares e 1 irregular; a ponta lisa, 5 adequadas, 1 regular e nenhuma irregular. A associação de ambaspropiciou 2 cavidades adequadas, 3 regulares e 1 irregular. CONCLUSÃO: Não houve diferença estatísticana qualidade das cavidades preparadas com pontas lisas, diamantadas ou na associação das duas. Quanto àavaliação realizada com os microscópios clínico e o de varredura, não houve diferença estatística entre eles.

OBJECTIVE: To evaluate the quality of root-end preparations using ultrasonic stainless steel and diamond coated tips used individually or associated. The cavity walls were analyzed using a clinical microscope and by scanning electron microscopy (SEM). MATERIAL AND METHOD: Eighteen single rooted mandibular premolars weresubmitted to apicectomy and root-end cavities were performed using ultrasonic tips. The teeth were divided according to the ultrasonic tip used. Group 1 (n=6) stainless steel tips. Group 2 (n=6) diamond coated tips. Group 3 (n=6) the cavity was done initially with a diamond coated tip and finished using a non-coated tip. Three scores were assigned to evaluate the quality of the cavity walls: 1 adequate; 2 regular; 3 inadequate. RESULTS: Diamond coated tip preparation showed 3 adequate cavities, 2 regulars and 1 inadequate. The stainless steel tip preparation showed 5 adequate cavities and 1 regular. The association of the tips showed 2 adequate cavities, 3 regulars and 1 inadequate. CONCLUSION: There was no statistically difference in the quality preparation for the analyzed groups. There was no statistically difference in the evaluation using a clinical microscope or SEM.