The Effect Of Different Polishing Methods On The Roughness Of Enamel Surface After Ultrasonic Scaling

Objective: This paper aimed at studying the effect of different polishingmethods on the roughness of human enamel surface after ultrasonic scaling bythe experiment in vitro, and identifying the influence factor of the polishingeffect. Therefore, we could select the safe and effectual polishing methods onclinical application.Method:80human premolars were collected in StomatologicalDepartment Hebei Medical University Second Affiliated Hospital due toorthodontic treatment demands. These teeth which were complete,flat,smooth, with no deposition of pigment and plaque, were filtered andextracted. Tetracycline teeth, dental fluorosis teeth, enamel hypoplasia teeth,caries teeth were excluded. After eliminating and clearing the periodontalligament and other attachments, the teeth were reserved in4℃physiologicalsaline.Each coronal enamel of the buccal side of the tooth was polished by600#,1000#,1500#,2000#water sandpapers andW14-03#,W10-04#,W7-05#,W5-06#metallographical sandpapers,makingthem ideal for the formation of mirror. Then the teeth were rinsed by distilledwater.80specimens were randomly divided into eight groups,each with10teeth:Group1: no ultrasonic scaling（blank control group）;Group2: ultrasonic scaling;Group3: polished by diping rubber cup in prophylaxis paste afterultrasonic scaling;Group4: polished by diping rubber cup in toothpaste after ultrasonicscaling; ultrasonic scaling rubber cup after dip in polishing; Group5: polished by diping prophy brush in prophylaxis paste afterultrasonic scaling;Group6: polished by diping prophy brush in toothpaste after ultrasonicscaling;Group7: sandblasting polishing after ultrasonic scaling;Group8: polished by silicone OneGloss IC after ultrasonic scaling.The method of ultrasonic scaling: the ultrasonic scaler was set tointermediate output power and water velocity. Under the pressure of0.4~0.5N (testing with YP6001industrial electronic balance), the supragingivalworking end ran across the enamel surface horizontally and parallelly to theenamel surface. The time of ultrasonic scaling remained20second.The method of polishing:1The prophylaxis paste was diffused throughwater and was brushed onto the surface of teeth by the rubber cup or byprophy brush installed on the low-speed dental handpiece (the speed of15000r/min). The rubber cup or prophy brush was perpendicular to the surface ofenamel. The pressure of polishing was about0.3N. The time of polishingremained20s.2The process was the same as1. But applied toothpaste insteaded ofthe prophylaxis paste.3The sandblasting machine’s hydraulic pressure and air pressure were setto intermediate. The sandblast nozzle was perpendicular to the surface ofenamel. The distance between sandblast nozzle and enamel was about3~5mm. The pressure of polishing was about0.3N. The amount of sand eachtooth was0.4~0.5g. The time of polishing remained20s.4The silicone OneGloss IC was used insteaded of the rubber cup orprophy brush, and prophylaxis paste or toothpaste was not applied. Thesilicone OneGloss IC was parallel to the surface of enamel.The pressure ofpolishing was about0.3N. The time of polishing remained20s.The same personnel accomplished the whole process in strict accordancewith the instructions of the instruments and materials. The same ultrasonic scaler, the same low-speed dental handpiece and the same sandblastingmachine was used in the experiment.The surface roughness (Ra value) of the buccal sides of all specimenswas measured by measuring instrument of the surface roughness. Thesampling length was0.25mm, the evaluating length was1.5mm, the rate ofadvance was0.1mm/s. Five points were taken randomly in the processed areaof each specimen, and roughness was tested. All of the results were averaged.The surface roughness (Ra) of eight groups was inputed into the SPSS13.0statistical software. Kruskal-Wallis H test was used to analyze overalldifferences. According to analysis of variance of the rank transformation,SNK-q test was used for a binary comparison. As a=0.05, if P value is <0.05, there is a difference statistically.Results: Kruskal-Wallis H test was used to analyze overalldifferences.According to a=0.05, H=73.363, P <0.05, there was statisticalsignificance,and it was thought that the surface roughness of eight groupswere not totally same.According to analysis of variance of the rank transformation, SNK-q testwas used for a binary comparison among eight groups. It indicated that therewas no significant difference statistically in the surface roughness betweengroup3and group4(P>0.05). The surface roughness of the rest of eightgroups was different from each other (P <0.05).Conclusion:1The surface roughness of enamel increased remarkably after ultrasonicscaling. Also, the polishing could decrease the surface roughness of theenamel significantly.2When polishing methods and polishing materials were different,polishing effect varied.1) In the group of the rubber cup, the toothpaste had slightly betterpolishing effect than the prophylaxis paste, but there was no significantdifference statistically.2) The polishing effect of prophy brush+prophylaxis paste was worst among the groups.Whereas, the polishing effect of silicone OneGloss IC wasbest.