ผลของทิศทางการฉายแสงที่มีต่อความแข็งแรงการยึดติดทนแรงเฉือนของแบร็กเกตจัดฟันโลหะและระดับการบ่มของวัสดุยึดติดเรซินที่บ่มตัวด้วยแสง / เสาวลักษณ์ ผดุงวรศาสตร์ = Effect of light curing direction on the shear bond strength and degree of cure of a light-cured orthodontic adhesive / Saowaluk Padungvorasart
Objective To study the effect of light curing direction on the shear bond strength and degree of cure of a light-cured orthodontic adhesive. Methods 72 extracted human premolar teeth, 12 teeth in each group, were bonded to stainless steel brackets with a light-cured adhesive, cured by light in 3 different direction; 1) mesial & distal direction 2) buccal direction and 3) occlusal direction. The samples were tested for the shear bond strength by a universal testing machine at 5 minutes and 24 hours after light activation. In the degree of cure study, a sample tooth was bonded to stainless steel brackets with a light-cured adhesive, by curing with 3 different light as mentioned in the shear bond strength study. The adhesive was tested for the degree of cure by Fourier transform infrared spectroscopy 5 samples repeatedly at 5 minutes and 24 hours after light activation. Results The shear bond strengths of all light direction testing groups were not significantly different in both 5 minute and 24 hours after bonding. The degree of cures of a light-cured adhesive, cured by mesial & distal light direction, were significantly higher than those cured by buccal light direction. However the degree of cures by occlusal light direction were not significantly different from those two groups. Conclusion Light curing direction has an effect on degree of cure of a light-cured orthodontic adhesive but it has no effect on the shear bond strength.