The Experiment Study Of Several Resin-removal Methods On Enamel Surface

Objective: The fixed appliance orthodontic treatment is a kind of efficient technology, More and more doctors and patients have been accepted it. Because of etching and oral environmental impact, especially banding bracket and remove the adhesive on the enamel surface can cause tooth damage. The fixed orthodontic treatment damage on enamel surface is inevitable. Therefore, how to remove the adhesive remnant safely and effectively focus on orthodontics professional research. Improper removal methods can easily result in the structure of the surface enamel loss and damage, its roughness increases can lead to plaque and enamel surface caries. If the adhesive remnant does not clean completely can lead to the tooth surface discoloration appearance. At present, the most common method to removal the adhesive remnant is grinding in clinical, but it is more difficult to control when they are operated, such as, if grinding too little it is easier to leave the adhesive remnant on the surface; and grinding too much, the enamel loss may be larger, and the surface leaves scratches, result in the roughness increasing and easy to lead to plaque,calculus and pigment deposition. Other methods such as: ultrasonic scaling, sandblasting, remove resin pliers and so on,they could reduce the damage to the enamel surface in theory, but each has its own advantages and disadvantages. Ultrasonic scaling can cause deep scratches on tooth surface if use improper, so they need polishing treatment. There still remains controversy about and whether it is necessary to polishing after sandblasting. Silicon particle is a kind of abrasive polishing materials, which includes polishing particles, and it's hardness between the resin and the enamel so don't easy to cause enamel injury, when used with the different pressure can have double effect, grinding, polishing once completed. However, some studies have shown that silicon particles can be prolonged grinding time significantly. Remove resin pliers injury the enamel surface less but difficult to completely remove the resin. The tooth surface will be caused a certain degree of enamel loss after a series of orthodontic treatment, Some studies show that enamel loss between the range of 1~52um. From the clinical point, enamel loss is not significant about the entire enamel thickness. so it was less affected than the surface roughness. Therefore, the roughness become the main evaluation index in this experiment. This study is aimed at the comparison of several methods to remove adhesive remnant, and evaluate their effectiveness, in order to provide reference for clinical treatment.Methods: By 15 times the magnifier, we choose 70 premolars selection of extracted due to orthodontic treatment (age 12~16 years old,on average 14 years). The teeth surface are perfect without cracks, caries and any chemical processing, such as hydrogen peroxide and so on, tetracycline pigmentation teeth and dental fluorosis are refused. All the teeth surface were cleaned according to conventional methods, numbered, and tested by profilometer on all the teeth buccal central. And bond brackets with conventional methods: rising teeth to make them clean, drying with no oil compressed air, then spreading 37% phosphoric acid evenly on the central area of tooth surface for 60 seconds, the area coated by phosphoric should be slightly larger than bracket base, then rising with air guns 30 seconds, drying with compressed air, then bonding brackets with JINGJIN composite resin according to distructions. 10 minutess after bonding all teeth are placed in saline solution, 37℃environment. A week later remove all the brackets with bracket removing pliers. All the teeth were randomly divided into 7 groups, each has 10 premolars. Group 1: tungsten carbide burs + polishing cups; Group 2: tungsten carbide burs + silicon particles; Group 3: tungsten carbide burs + sandblasting; Group 4: ultrasonic scaling + polishing cups; Group 5: ultrasonic scaling + silicon particles; Group 6: ultrasonic scaling + sandblasting; Group 7: silicon particles. After deal with, record the processing time in each group, test the tooth surface roughness again, observe tooth surface by 15 times magnifier and assess with the adhesive remnant index(ARI) score. Each group were randomly selected a sample and a perfect tooth(with standard experimental), with high-speed diamond bur cut the teeth of experimental zone to the size of 5mm×5mm, thickness 2~3 mm, washing with compressed air and water for 20s, cleaning 10 minutes by the ultrasonic cleaning device, drying 24 hours in constant temperature drying oven at 37℃. The samples will be used ion coating device sprayed gold,and the specimens configuration were examined microscopically with the scanning electron microscope.All the data is operated by SPSS16.0, P<0.05 is considered as statistically significant difference.Results: 1.The surface roughness has statistical significance. In the groups of use tungsten carbide burs: Group 1, Group 3 of roughness values increased and can not achieve orthodontic clinical. While in the groups of use ultrasonic scaling: Group 4, Group 5, Group 6 of roughness values decreased. The groups use of silica particles: Group 2, Group 5, Group 7 of roughness values also decreased.2.The time used in different groups has statistical significance. Group 1, Group 2 and Group 3 used the shortest time, while Group 7 used the longest.3. The ARI in different groups has statistical significance. Group 7 has statistically significant difference between Group 1, Group 3 and Group 6, while the other groups of the difference is not statistically significant.4.The SEM show that the treated tooth surface have different degrees of injury, while the silica particles after the treatment, surface scratches shallower, smaller tooth surface damage.Conclusion: 1.The tungsten carbide burs has the highest efficiency, but can cause more damage. However, silicon particles can protective tooth surface, reducing the roughness.2.Ultrasonic scaling with the polishing, silicon particles and the sand blasting can reduce the tooth surface roughness.3.The method of silicon particles damage the tooth smaller, the ARI smaller, but the efficient less.4.We can improve our work efficiency and reduce the damage if we use silicon particles polishing after tungsten carbide burs doing. This is a better method. However, it should avoid causing irreparable damage in the use of carbon-tungsten.