Effect of Chemical Pretreatment of Teeth on Fissure Sealant Microleakage

OBJECTIVES: This study investigated a method of improving the effectiveness of the sealing procedure using strong bases (NaOH or tetra-butyl ammonium hydroxide, TBAH) as a chemical pretreatment for removing organic debris from the fissure system prior to resin-based sealant application. Pretreatment was hypothesized to improve effectiveness.

METHODS: Molar teeth free of decay were selected following gamma irradiation. NaOH (1.0 Normal) was applied to one group (n=10) for 60 sec, rinsed, dried, etched and sealant applied (Ultraseal XT Plus). Another group (n=10) was treated with 5.5% TBAH for 60 Sec rinsed, dried, etched, and sealed. A third group (n=18) served as controls receiving sealant without any pretreatment. One half of each group was subjected to either 5000 thermal cycles(5-55șC) or 50000 mouth-motion occlusal 50N load cycles. All teeth were immersed in a caries indicator dye (Sable Seek) for 24 hours to allow dye penetration, rinsed, sectioned and examined with light microscopy. Microleakage, fissure type, and unfilled area at the base of the fissure were measured and compared with ANOVA. Microleakage was measured as the length of dye penetration as a percentage of the total length of the sealant-tooth interface.

RESULTS: Samples pre-treated with either base showed an average of 43%±22 microleakage as opposed to an average of 39%±28 microleakage for samples having had no pre-treatment. Microleakage averages were all statistically equivalent regardless of fissure type, unfilled area at the base of the fissure, or pretreatment used before sealing. In all groups thermocycling resulted in significantly less (p<0.05) microleakage on average (27%±21) when compared to load cycling (48%±16).

CONCLUSIONS: Pretreatment of the fissure system with strong base (NaOH or TBAH) before etching does not add to the effectiveness of the resin sealant. When testing tooth sealant microleakage, mechanical cycling appears to be an effective method of simulating time in function.