The Comparative Study On Primary Dentin Surface To The Resin Shear Strength Influence With Er:YAG Laser And High Speed Handpiece Treatment

Objective: A comparative study of Er:YAG laser and high speed handpiece effecton the shear strength of the composite resin dentin after treatment of primary teeth.Methods: Collecting124mandibular primary teeth that are in accordance with thestandard, burring in super hard plaster separately whose size is3cm×5cm. And randomlydividing into4groups: A, B, C, D, Each group has31teeth. Group A and group B withthe Er:YAG laser (Power is2W) exposure of primary teeth labial dentin, group C andgroup D with high speed handpiece exposure labial dentin of primary teeth. Selecting asample from each group randomly and observing by scanning electron microscope andcomparing, and then group A and group C were acid etched. The rest120samples will betested and statistically analysis shear strength after filling composite resin. Results: SEMshowed that primary teeth dentin surface uneven Er:YAG laser processing, theappearance is rough and has fish squamous, wavy, the surface is cleaning without smearlayer, dentin tubule is clear, peritubular dentin is the intertubular dentin protrudes out ofthe surface, a large number of opened dentinal tubules were "cuff" appearance. Toothsurface which is treated by high speed handpiece leaves stripes, section is relatively flat,smear layer surface covered with a layer of dense, and accompanied by obvious cracks,dentin structure is not clear, dentin sections occasionally appear opened dentinal tubules.The analysis of shear strength of group A is（11.45±3.79）Mpa, group B is（9.78±3.35）Mpa, group A and group B have not statistically difference (P>0.05), it is not consideredthat shear strength of group A and group B have difference. Group C is（8.97±4.03）Mpa,group D is（5.90±3.29）Mpa, group C and group D have statistical significant differences(P<0.05), it can be considered that the shear strength of group C and group D weredifferent. Group A and group C were statistically significant difference (P<0.05), it can be considered that the shear strength of group A and group C were different. group B andgroup D have statistical significant differences (P<0.05), it can be considered that theshear strength of group B and group D were different. Conclusion: Primary teeth dentinsurface use power of Er:YAG laser treatment of2W, whether it is combined with acidetching can increase the shear strength with composite resin. High speed handpiececombined with acid etching of primary teeth dentin can increase the shear strength ofcomposite resin.