| Objective: This study used SEM,stereo microscope and micro tensile bond strength test to determine the effect of different self-etching adhesive processing methods on fluorosis enamel bonding strength,such as different acid etching adhesive system,curing light,self etching adhesive processing time.Helping clinicians to choose proper treatment methods according to the condition of dental fluorosis and obtaining better repair effect.Methods: This project was divided into the following three experiments.Experiment one: the effect of different curing light on enamel bond strength.Collecting 120 intact and without caries orthodontic first premolar in the high fluoride area,stored in 0.5% Benza.According to the score of dental fluorosis TFI,collected teeth were divided into 4 groups(normal occlusion group TFI=0,mild dental fluorosis group TFI=1-3,moderate dental fluorosis group TFI=4-6,severe dental fluorosis group TFI=7-9),each group had 30 teeth.Then according to the type of adhesive,each group was randomly divided into 3 subgroups(OptiBond All-In-One group,Adhese group,Adper Single bond plus group),which had 10 teeth.Selecting from the range of teeth of buccal and lingual amelocemental junction above 0.5mm to below 2mm cusp as the experimental site,die stone premium was used to fasten tooth roots,then using high-speed diamond bur mill 1mm to obtain a flat surface.According to the situation of each group,different binders were used for acid etching and bonding,filled composite resin Z350 4mm,and each layer of 2mm was solidified by 40 s.The specimens were placed into distilled water at 24 h.The slow grinders of diamond saw blade was used to cut the teeth resin filling surface in the case of vertical warter flow,to obtain several 1mm~*1mm~*8mm experimental specimens.Selecting 2 morphological rules from specimens without crack as test materials,it was fixed on the dental fixture special,through the electronic universal testing machine to measure the maximum micro tensile bond strength,the loading speed was 1mm/min.After measured,observing the fracture mode on the stereo light microscope with magnification of ~*45 times.Experiment two: the effect of different curing light on enamel bond strengthCollecting intact orthodontic first premolar,which was 30 moderate dental fluorosis,and stored in 0.5% Benza.According to the type of light curing lamp(Bluephase? 20 i,Elipar Freelight 2,ALC-50),the collected teeth were divided into 3 groups,each group 10 teeth.Selecting from the range of teeth of buccal and lingual amelocemental junction above 0.5mm to below 2mm cusp as the experimental site,then using high-speed diamond bur mill 1mm to obtain a flat surface.35% phosphoric acid 1min,washing drying,coating total etching adhesive Adper Single bond plus.According to the requirement of the group,to choose the appropriate light curing lamp,light curing 10 s.Then filled composite resin Z350 4mm,and each layer of 2mm was solidified by 40 s.The specimens were placed into distilled water at 24 h.The slow grinders of diamond saw blade was used to cut the teeth resin filling surface in the case of vertical warter flow,to obtain several 1mm~*1mm~*8mm experimental specimens.Selecting 2 morphological rules from specimens without crack as test materials,it was fixed on the dental fixture special,through the electronic universal testing machine to measure the maximum micro tensile bond strength,the loading speed was 1mm/min.After measured,observing the fracture mode on the stereo light microscope with magnification of ~*45 times.Experiment three: The effect of self-etching adhesive processing time on fluorotic enamel bonding.Collecting 240 intact and without caries orthodontic first premolar in the high fluoride area,stored in 0.5% Benza.According to the score of dental fluorosis TFI,collected teeth were divided into 4 groups(normal occlusion group TFI=0,mild dental fluorosis group TFI=1-3,moderate dental fluorosis group TFI=4-6,severe dental fluorosis group TFI=7-9),each group had 30 teeth.Then each group according to the bonding processing time was divided into 6 sub groups(15s,30 s,60s,90 s,120s,150s),which had 10 teeth.Selecting from the range of teeth of buccal and lingual amelocemental junction above 0.5mm to below 2mm cusp as the experimental site,then using high-speed diamond bur mill 1mm to obtain a flat surface.According to the conditions of each subgroup,the self-etching adhesive OptiBond All-In-One was coated on fluorosis enamel,standing 15 s,30s,60 s,15s,90 s,150s,10 s,120s,light curing 10 s.Then filled composite resin Z350 4mm,and each layer of 2mm was solidified by 40 s.The specimens were placed into distilled water at 24 h.The slow grinders of diamond saw blade was used to cut the teeth resin filling surface in the case of vertical warter flow,to obtain several 1mm~*1mm~*8mm experimental specimens.Selecting 3 morphological rules from specimens without crack as test materials.Of which 1 specimens was removed the impurities by ultrasonic oscillation 60 s,putted in 100% ethanol for 2 hours to surface dry,sputter,and morphology of the enamel adhesive interface was observed by scanning electron microscopy.Selecting 2 morphological rules from specimens without crack as test materials,it was fixed on the dental fixture special,through the electronic universal testing machine to measure the maximum micro tensile bond strength,the loading speed was 1mm/min.After measured,observing the fracture mode on the stereo light microscope with magnification of ~*45 times.Result:Experiment one: in the normal tooth group,the adhesive strength of the 3 kinds of binders were good.(P>0.05).The most common type of fracture is mixed failure,and OptiBond All-In-One is the largest group of mixed damage;Mild and moderate dental fluorosis group,Adper Single bond plus and OptiBond All-In-One can obtain the strong bond strength better than Adhese(P<0.05).The most common fracture mode was the bonding surface damage,moderate dental fluorosis group Adhese was the most damage group bonding surface;Severe dental fluorosis group,total etch bonding system was better than self etching adhesive system,followed by Adper Single bond plus>OptiBond All-In-One > Adhese(P<0.05).The most common failure mode was the failure of the bonding surface,and the Adhese group was the most popular group;Experiment two: three group received the micro tensile bond strength of dental fluorosis were significant difference,Bluephase? 20 i >FreeLight > ALC-50(P<0.05).the most common failure mode was the failure of the bonding surface,and ALC-50 was the most popular group.Experiment three: the morphological characteristics of the specimens interface were changed with different time of acid etching;Normal enamel bonding strength was higher than that of fluorosis enamel(P<0.05),30 s and 15 s can obtain better bonding effect;Mild and moderate dental fluorosis were the best adhesive effect in 120s(P<0.05);Severe dental fluorosis in the 90 s group got the maximum adhesion(P<0.05);The most common fracture mode was the bonding surface damage,15 s group was the most popular group.Conclusion:For the flourosis dental enamel,different treatment methods had great influence on the enamle bond strength.Clinicians can choose appropriate methods according to the severity of dental fluorosis,such as acid etching adhesive system,different curing light,self etching adhesive processing time,to obtain a better bonding strength and reduce the failure rate. |
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