ผลของระยะเวลาก่อนการบ่มด้วยแสงต่อกำลังแรงยึดแบบเฉือน และความยาวของเรซินแทก ของวัสดุผนึกหลุมร่องฟันชนิดหนึ่งในฟันกรามน้ำนม / ดวงธิดา ชุติมานุตสกุล = Effect of the time-lapse before light curing on the shear bond strength and the tag length of a sealant in primary molars
To compare the effect of the time-lapse before light curing on the shear bond strength and the tag length of the commercial sealant, Concise TM in primary molars. To study the shear bond strength, sixty samples of buccal or lingual surfaces of primary molars were divided randomly into three groups of 20 samples each, corresponding to the time-lapse of 5, 10 and 30 seconds before light curing of the sealant buttons on the enamel surfaces. After curing, all samples were stored in distilled water for 24 hours before the shear bond strength was tested with a universal testing machine. The study of tag length was performed using 12 buccal surfaces of primary molars. They were divided into 2 groups of 6 samples each. Two different intervals of time-lapse before light curing were studied on the same sample. The first group were 5 and 10 seconds; the second group were 10 and 30 seconds. After curing, all samples were stored in distilled water for 24 hours. Then each sample was embedded in epoxy resin. Two different intervals of time-lapse before light curing were obtained from each sample by long axis sectioning. The samples were polished until the cutting surfaces were smooth then etched with a phosphoric acid solution. The samples were rinsed thoroughly with water, allowed to dry and coated with gold particles. They were then examined by a scanning electron microscope. The study of the shear bond strength shows that the longer the time-lapse before light curing is, the higher the shear bond strength is. The average shear bone strengths of 5-, 10- and 30-second groups are 10.76 +_2.42, 11.96 +_1.76 and 14.66 +_3.23 Mpa, respectively. The average shear bond strength of 30-second group is significantly highest among the other groups at P<0.05. The average shear bond strength of 5-second group is the lowest one but statistically insignificant compared with the 10-second group. The study of the tag length shows that the average tag length of 5-, 10- and 30-second intervals are 7.93 +_1.40, 9.08 +_2.15 and 8.68 +_1.59 Microm, respectively. The average tag length of 10-second interval is the longest and has statistically significant difference only when compared with that of 5-second interval at p<0.05. The average tag length of 5-second interval is the shortest one but statistically insignificant compared with that of 30-second interval. This study indicates that the time-lapse before light curing has more effect on the shear bond strength than that on the tag length of the commercial sealant, Concise TM in primary molars.