Study On The Correlation Between Coating Method And Interface Sealing Of All-acid And Self-acid Sonding Systems

Objective:By comparing and analyzing the effect of different times of self-acid and all-acid adhesive on the sealing of tooth bonding interface,we expore the best coating method of adhesive,evaluate the effect of different bonding system on the sealing of tooth bonding interface edge,and provide experimental reference for rational use and correct selection of a-dhesive in clinic.Methods:Experiment 1:35 third molars extracted in nearly one month were collected（required to have normal shape,complete crown,no hidden crack,no root absorption and com-plete closure of apical foramen）,and the curette was used to remove the calculus and scalpel to clean the periodontal ligament,and stored in 4℃and saline.The cavity shape of 4 mm×3m m×2 mm was prepared in the buccal lingual enamel bone boundary crown square1.Randomly divided into 7 groups,5 in each group,10 holes and 10 samples,respectively,A0 group（blank control group）;B1 group（self-acid adhesive coating once）;B2 group（self-acid adhesive coa-ting twice）;B3 group（self-acid adhesive coating three times）;C1 group（all-acid adhesive co-ating once）;C2 group（full-acid adhesive coating twice）;C3 group（full-acid adhesive coating three times）.Each group handles the bonding interface according to the operation requirement-s.After the resin filling was finished,the apical foramen was sealed with self-coagulating res-in,and the nail polish was evenly applied1 mm place around the edge of the hole.All sample teeth were immersed in alcohol solution of 37℃,0.1%rhodamine B isothiocyanate for 24 h,a-nd washed with distilled water to remove the net dye^[1].Two pieces of the tooth were cut form the buccal and tongue direction in the experimental area parallel to the long axis of the tooth body with a diamond needle,and the specimen was polished with 600,800 and 1200 meshsandpaper until light transmission.The length and morphology of microleakage and nanoleak-age were measured by laser scanning confocal microscope.Experiment 2:According to the inclusion criteria of experiment 1,36 isolated third molars were selected to remove the enamel of the occlusal teeth and expose the dentin to form a unifo-rm adhesive surface.Randomly divided into 6 groups,each group of 6 teeth,respectively,D1group（self-acid adhesive coating 1 time）;D2 group（self-acid adhesive coating 2 times）;D3 g-roup（self-acid adhesive coating 3 times）;E1 group（full-acid adhesive coating 1 time）;E2 gr-oup（full-acid adhesive coating 2 times）;E3 group（full-acid adhesive coating 3 times）.The a-dhesive was mixed with rhodamine B and the adhesive interface was treated according to the operation requirements（the treatment mode was the same as experiment 1）.After the resin lay-er of 1 mm was molded,the apical foramen was sealed with self-coagulating resin.All the sa-mple teeth were immersed in 37℃saline 24h,the teeth were cut continuously from the bucca-l tongue direction in the experimental area parallel to the long axis of the tooth body by using a Emery Carpin to polish the specimen with 600,800,1200 mesh sandpaper until transparent.The penetration depth of resin monomer in dentin tubules and the morphology of mixed layer were measured by confocal laser scanning microscopy.The experimental data were analyzed by SPSS23.0 software:the values were expressed by（（?）±s）.The data were tested by normality test and homogeneity of variance test.One-way analysis of variance（One-way ANOVE）was used to compare the overall difference between the mean numbers of each group（P<0.05）.The LSD-t method was used for pairwise compari-son.The test levelα=0.05,and the difference was statistically significant by 0.05.Results:（1）The microleakage results showed that the microleakage values of B2 group（self-acid coating 2 times）and C2 group（total acid coating 2 times）were the lowest（P<0.05）,and the difference was not statistically significant（P all>0.05）.（2）The results of nanoleakage showed that the nanoleakage values of B2 group（self-acid coating 2 times）and C2 group（all-acid coating 2 times）were the lowest（P<0.05）,and the comparison of nanoleakage values of two adhesive systems with the same number of coating times,the self-acid bonding system w-as lower than that of the whole acid bonding system（P all<0.05）.（3）D1 group（self-acid coati-ng 1 time）and E1 group（total acid coating 1 time）had the lowest permeation values of resin monomer（P all<0.05）.There was no significant difference between the D2 group and the D3group,the E2 group and the E3 group（P>0.05）.The self-acid bonding system was lower than the all-acid bonding system（P all<0.05）.（4）The observation results of the morphology of the mixed layer under microscope showed that the mixed layer was thin and uneven when the two bonding systems were coated once,the resin was suddenly broken,the coating was more unif-orm whencoated twice,the resin process had no obvious fracture,and the mixed layer formed when coated 3 times is uneven.Conclusion:（1）When the all-acid and self-acid bonding systems were coated twice,the microleakage and nanoleakage were the lowest.When the coating times reached 3 times,the microleakage and nanoleakage value became larger,there was no obvious difference between the whole acid and self-acid bonding systems,and the nanoleakage of the whole acid bonding system was higher than that of the self-acid bonding system.（2）When the whole acid and self-acid bonding system was coated twice,the penetration length of the resin monomer was the la-rgest and the most uniform,and the quality of the mixed layer was the highest,and the resin monomer length of the all-acid bonding system was larger than that of the self-acid bonding system.