Study Of Two Kinds Of Adhesive For Bonding Of Shear Bond Strength Between All-ceramic And Dental Fluorosis

Objective:The aim of this study was to evaluate the bonding efficacy of CAD/CAM all-ceramic material with normal and moderate fluorosis dentin with two universal adhesives.It provides a theoretical basis for clinical selection of adhesives suitable for the inlay repair of dental fluorosis.The study also evaluated the clinical effect of the application of CAD/CAM all-ceramic restorative system for fluoresced dentine.Methods:1.In Experiment 1,40 normal and 40 moderate dental fluorosis(under the Dean classification)were removed due to periodontal disease or resistance dentition.Superficial dentine was exposed and grounded with silicon carbide paper under water.Teeth were embedded in seli-curing resin block.It is documented whether enamel was completely removed by stereomicroscope.The sample was divided into the normal teeth groups(N1,N2,N3,N4)and the fluorosis dentine groups(F1,F2,F3,F4).80 CAD/CAM Celtra Duo slices(sectional area:4×4mm~2,thickness:4mm)were randomly divided into 8 groups,with10 slices in each group.The slices were grounded with silicon carbide paper under water.Group N1 and F1 were bonded to Celtra Duo slices with RelyX Ultimate Cliker universal adhesive in the acid-etch mode.Group N2 and F2 were bonded to Celtra Duo slices with RelyX Ultimate Cliker universal adhesive in the self-etch mode.Group N3 and F3 were bonded to Celtra Duo slices with Bisco Duo-LINK SE Kit universal adhesive in the acid-etch mode.Group N4 and F4 were bonded to Celtra Duo slices with Bisco Duo-LINK SE Kit universal adhesive in the self-etch mode.All specimens were stored in water at 37?for 24h before undergoing 500 thermal cycles(5?to 55?).Slices were trimmed for shear strength and stressed in tension at a crosshead speed of 0.5mm/min.The fracture interfaces were evaluated by the SEM.2.In Experiment 2,30 normal teeth and 30 dental fluorosis cases with dental pulp diseases and prosthodontic treatment were randomly selected from August 2016-January 2018 in Guiyang Hospital of Stomatological.The cases with defect were treated using CAD/CAM system for Endo-overlays restoration,and Bisco Duo-LINK SE Kit universal adhesives in acid-etch modes.During postoperative visits in March,June,and December,evaluation of the treatment effect was conducted according to standards aligned with the United States Public Health Service.Results:1.On normal and moderate fluorosis teeth with the same type of bonding method for the same type of universal bonding system,the adhesive strength of dentin of moderate fluorosis teeth was lower than that of the normal teeth(statistically significant at P<0.05).The same universal bonding system was applied on normal teeth and moderate fluorosis teeth,and the values between the acid-etch with self-etch were statistically different(significant at P<0.05).The bonding strength of two universal bonding systems had no significant difference(P>0.05).2.For the groups of normal teeth,the fracture mode of cohesive failure was observed in two universal bonding systems.For the groups of moderate dental fluorosis,the fracture mode of cohesive failure was observed in RelyX Ultimate Cliker bonding system used in acid-etch and self-etch modes,whereas the fracture mode of adhesive failure was observed in Bisco Duo-LINK SE Kit universal adhesives used in self-etch mode.3.The normal teeth group and the dental fluorosis group for Endo-overlays were observed for one year according to the USPHS.The results showed Prosthesis abrasion,edge coloring,secondary caries,and grade A was above 100%in normal teeth group and dental fluorosis group.On prosthesis fracture,the grade A was above 89.66%in normal teeth group and above 88.46%in dental fluorosis group.Abscission of prosthesis,the grade A was above96.55%in normal teeth group and at 92.31%in dental fluorosis group.In terms of marginal adaptation,the grade A was above 93.10%in normal teeth group and at 96.15%in dental fluorosis group.The normal teeth group and the dental fluorosis group had no significant difference(P>0.05).Conclusion:1.In the dentine adhesion of normal and moderate fluorosis teeth,the total acid etching adhesion of two common adhesion systems can achieve good bonding strength than self etching.2.The adhesive strength of dentin of moderate dental fluorosis was lower than that of the normal teeth.3.Satisfactory clinical results can be achieved in the restoration of Endo-overlays of fluorosis teeth according to standards aligned with the United States Public Health Service.