| Objectives:The effect of the angle of the curing light source on the marginal sealing of the light cured resin composites during the process of teeth filling was studie in this research,in order to improve the bonding effect by improving the light curing plan,that is,to reduce the occurrence of micro-leakage and secondary caries,increase the success rate of composite resin filling,and reduce the rate of shedding.Methods:105 human permanent third molars were collected in the Affiliated Stomatological Hospital of Kunming Medical University.the roots of teeth were cut off,and the crown of them were split from mesial side to distal side,departing into buccal piece and lingual/palatal piece.Class I cavity with a depth of 2mm,with a length and with a width of 3.0 mm was prepared on each pieces of the crown.Totally 210 samples were prepared and placed in 1%chloramine solution for storage at 4℃.210 samples were randomly divided into 10 groups,namely Group S00:AdperTM Single Bond 2+were irradiated at 0°Angle(The curing light source irradiates the composite resin and the adhesive at the same angle);Group S30:AdperTM Single Bond 2+were irradiated at 30° Angle;Group S45:AdperTM Single Bond 2+were irradiated at 45° Angle;Group S60:AdperTM Single Bond 2+were irradiated at 60° Angle;Group S90:AdperTM Single Bond 2+were irradiated at 90° Angle;Group E00:AdperTM Easy one+were irradiated at 0° Angle;Group E30:AdperTM Easy onerwere irradiated at 30°Angle;Group E45:AdperTM Easy one+were irradiated at 45° Angle;Group E60:AdperTM Easy one+were irradiated at 600 Angle;Group E90:AdperTM Easy one+were irradiated at 90° Angle.Each sample in different group is filled according to the manufacturer’s instructions and was cured with LED curing light at different projected angle.All samples was cured from the crown to the root,so the crown was near-projection point,and the root was the far-projection point.temperature cycle was conducted according to ISO standard TS 11405:2015(E),and the combination of filling material and tooth tissue,and the thickness of adhesive interface were observed with scanning electron microscope;1%methylene blue staining and stereomicroscope were used to detect the degree of microleakage quantitatively.Kruskal-wallis H test and Man-Whitney rank sum test were used for statistical analysis of penetration grade,and Statistical significance was set at α=0.05.Results:There different degrees of micro-leakage at near-projection pointand far-projection points in each group.There was no significant difference between S90 group and S60 group(P>0.05),but there was significant difference between S00 group,S30 group and S45 group(P<0.05).There was no statistical significance between S60 group and S45 group(P>0.05),but there was statistical significance between S00 group and S30 group(P<0.05).There was statistical significance between S45 group and S00 group(P<0.05).There was no significant difference between S30 group and S00 and S45 groups(P>0.05).Comparison of the degree of microleakage in the side far from the irradiation point:there was statistically significant difference between the S90 group and the S30 group(P<0.05),while there was no statistically significant difference between the other groups(P>0.05).Among the five self-etching groups,the degree of microleakage at the near exposure point was as follows:there was statistical significance between the E90 group and the adult E00,E30,E45 and E60 groups(P<0.05).There was no significant difference between E60 group and E45 group(P>0.05),but there was significant difference between E00 and E30 groups(P<0.05).The difference between E45 group and E00 group was statistically significant(P<0.05).There was no significant difference between E30 group and E00 and E45 groups(P>0.05).Comparison of the degree of microleakage in the side far from the projection point:there was statistical significance between the E90 group and the E00 and E45 groups(P<0.05).There was no statistical significance in other groups(P>0.05).There was no significant difference between the two bonding systems at the same projection Angle(P>0.05).Conclusions:Both the total-etch adhesive system and the self-etch adhesive system have good edge tightness to the dentin.The micro-leakage between the dentin and the filling material is affected by the change of the light projection Angle of the curing light source.The micro-leakage of the two systems at the near-projection point is larger than the far-projection point.When the light Angle was 0°,the micro-leakage between the dentin and the filling material at the near-projection point is the largest.As the angle increases,the micro-leakage gradually decreases.When the light Angle was 90°,the micro-leakage between the dentin and the filling material at the near-projection point is the smallest.When the projection angle of the far-projection point is 90°,the micro-leakage is the smallest.SEM showed that the adhesion of the dentin interface may be related to the size of the micro-leakage. |
PDF Full Text Request