An evaluation of the effect of blood and human serum on the surface microhardness and surface microstructure of mineral trioxide aggregate.

AIM: Short-term and long-term evaluation of the effect of whole human blood or serum contamination on the surface microhardness value and microstructure of white and grey mineral trioxide aggregate (MTA). METHODOLOGY: Three groups of 10 samples for each type of MTA were prepared. The first group was mixed with and exposed to fresh whole human blood. The second and third groups were mixed with distilled water and exposed to fresh whole human blood or human serum, respectively. The control group samples were mixed with and exposed to distilled water. During preparation, 1 g of MTA was triturated with 0.33 g of the selected liquid using an amalgamator and placed inside borosilicate cylindrical moulds. The samples were treated with ultrasonic energy. Vickers surface microhardness values were compared after 4 and 180 days. Scanning electron microscopy (SEM) analysis was performed after 4 days. RESULTS: White MTA had a greater microhardness value than grey MTA in all groups. There was a significant difference between the control and the experimental groups (P < 0.00001). There was no significant difference between the microhardness values obtained after 4 and 180 days, apart from grey MTA mixed with blood or exposed to serum (P < 0.00001). SEM analysis showed the contaminated samples were devoid of acicular crystals that were prominent in the control groups. CONCLUSION: Blood contamination had a detrimental effect on the surface microhardness of MTA in the short and long term. If blood or serum contamination is unavoidable under clinical conditions, it might be preferable to use white MTA.

Microleakage assessment of pit and fissure sealant with and without the use of pumice prophylaxis.

OBJECTIVES: This study evaluated the effect of pumice prophylaxis on the level of microleakage around and between the sealant and enamel. MATERIALS AND METHODS: A total of 32 freshly extracted sound upper first premolars, assigned as suitable for sealant application, were chosen and divided randomly into two groups: (1) a test group, without prophylaxis; and (2) a control group, with prophylaxis. Sealant was applied to all teeth using the same conventional technique, with prophylaxis being omitted in the test group. The sealed teeth were thermocycled (120 x 30 s, 5 and 55 degrees C cycles) and then immersed in 2% Basic Fuchsin solution for 72 h. Each tooth was sectioned and examined for dye penetration under a stereomicroscope (x 60 magnification). RESULTS: No dye penetration was seen in 19 (29.6%) of the teeth in the test group and 36 (56.2%) of the teeth in the control group. Dye had penetrated to the base of the fissure in 31 (48.4%) of the teeth in the test group and 23 (35.9%) of the teeth in the control group. Using a chi-square test for trend, the frequency of microleakage was significantly higher in the test group compared to the controls (P < 0.016). CONCLUSION: Prophylaxis has a role in improving sealant retention. Removing this step may cause an increase in microleakage.