Effect Of Enamel Remineralization By Using Different Retainer Types After Fixed Application

Objectives: In this study, to observe the difference of enamelremineralization effect between using traditional Hawley retainer andvacuum-formed retainer after fixed application. At the same time, the effect ofremineralization by using different measures was investigated.Methods:1ParticipantsThere were30participants who had finished fixed application between2010and2011accepted remineralization application in the primary of retainerstage,10males and20females,15.4±3.5years,233teeth totally. Compared tofirst visiting photos, patients who had enamel demineralization before fixedapplication and carious cavitives in demineralization areas, orthodontictreatment history, predilection to cavity, enamel hypoplasia, dental fluorosis,tetracycline pigmentation or oral habit disturbances were excluded.2GroupsParticipants were treated as follows: numbered the patients by their visitingsubsequence, and assigned to two groups by using a random number table.Group A: used traditional Hawley retainer,15patients,15.0±4.3years,117teeth totally; Group B: used vacuum-formed retainer,15patients,15.0±2.3years,116teeth totally.Then the retainer groups were separated into three different remineralizainggroups in randomly:Group1: the control group, coated the teeth surface with0.9%sodiumchloride solution;Group2: applied fluoride protector（0.10%F—IvoclarVivadent, Switzerland）directly;Group3: acid etched （Gluma Etch35Gel, HeraeusKulzer, Germany） the demineralization area at first, then spread the fluoride protector on the wholetooth surface.Thus, separated the patients into the different treatment groups as follows:A₁: used traditional Hawley retainer and coated teeth surface by0.9%sodium chloride solution,15.3±2.2years,37teeth totally;A₂: used traditional Hawley retainer and applied fluoride protector（0.10%F-IvoclarVivadent, Switzerland） directly,15.8±4.5years,38teeth totally;A₃: used traditional Hawley retainer and acid etched （Gluma Etch35Gel,HeraeusKulzer, Germany） the demineralization area at first, then spread thefluoride protector（0.10%F-IvoclarVivadent, Switzerland） on the whole toothsurface,13.8±1.6years,42teeth totally;B₁: used vacuum-formed retainer and coated teeth surface by0.9%sodiumchloride solution,15.2±3.4years,40teeth totally;B₂: used vacuum-formed retainer and applied fluoride protector（0.10%F-IvoclarVivadent, Switzerland） directly,13.3±2.5years,35teeth totally;B₃: used vacuum-formed retainer and acid etched （Gluma Etch35Gel,HeraeusKulzer, Germany） the demineralization area at first, then spread thefluoride protector（0.10%F-IvoclarVivadent, Switzerland） on the whole toothsurface,15.5±3.3years,41teeth totally.3Remineralization treatmentAfter debonded the brackets, removed the leaved agents, polished teethsurface, rinsed teeth surface by distilled water15seconds, put cotton rolls toabsorb saliva, cleaned the enamel surface by alcoholic rolls, dried bycompressed air15seconds. Each participant had been taking threephotographs to record the demineralization of maxillary central incisor,maxillary lateral incisors, mandibular central incisor, mandibular lateralincisors and mandibular canine teeth. Then treated the patients as follows: A₁and B₁, coated the teeth surface with0.9%sodium chloride solution; A₂andB₂, applied fluoride protector（0.10%F-IvoclarVivadent, Switzerland） directly;A₃and B₃, applied fluoride protector（0.10%F-IvoclarVivadent, Switzerland）after acid etched （Gluma Etch35Gel, HeraeusKulzer, Germany）. Dried out the teeth surface to form a thin and clear layer by using open-air for1minute.Medical order: Don’t eat, drink, toothbrush or gargle within45minutes;Don’t toothbrush that day; Worn retainers from next day. Applied Colgattoothpaste（0.11%F-） and toothbrush to every participants. Given oral hygieneto the participants, used the rolling stroke method to brush teeth,2times a day,3-5minutes each time. Returned visiting every four weeks and repeated theabove operations at each time.4Data processingBefore configuration measurement tested the experimenter’ reliability,Kappa>0.75.The photos of first visiting and subsequent visiting were imported intocomputer. Then used ZWCAD2010software to measure the labial surfaceareas of index teeth and the areas of white spot lesions.Demineralization rate was defined as the white spot lesions divided by thearea of labial surface area of index teeth.The first visiting demineralization rate was defined as T0demineralizationrate. The three monthes’ demineralization rate was defined as T3deminerali-zation rate.Remineralization effect was the change of demineralization rate. It wasdefined as T0demineralization rate minus T3demineralization rate.5Statistical analyzedThe statistical analyses of all the data were performed by SPSS softwaredivision17.0. The test standard was α=0.05.Results:1Comparison of T0demineralization rate of Group A and Group B1.1The T0demineralization rate was0.18199±0.17755in Group A and0.18857±0.14474in Group B. There was no significant difference betweenGroup A and Group B （p=0.885, p＞0.05）.1.2To compare the T0demineralization rate within Group AThe T0demineralization rate was0.18017±0.13197in Group A₁,0.19049±0.24422in Group A₂,0.17674±0.18911in Group A₃. p=0.325, p＞0.05. There was no significant difference within Group A in baseline.1.3To compare the T0demineralization rate within Group BThe T0demineralization rate was0.22718±0.17744in Group B₁,0.16741±0.13267in Group B₂,0.20067±0.14708in Group B₃. p=0.30, p＞0.05. Therewas no significant difference within Group B in baseline.1.4Comparison of the T0demineralization rate between Group A and GroupBTo compare the baseline between A₁and B₁（p=0.101, p＞0.05）, A₂and B₂（p=0.178, p＞0.05）, A₃and B₃（p=0.854, p＞0.05）. There was no significantdifference in baseline.2Comparison of the remineralization effect2.1Group A2.1.1The remineralization effect was0.13430±0.06342in Group A₁，0.17621±0.10930in Group A₂,0.17471±0.08310in Group A₃.2.1.2To compare the remineralization effect between A₁and A₂（p=0.040, p＜0.05）, A₂and A₃（p=0.042, p＜0.05）, A₁and A₃（p=0.939, p＞0.05）. Theremineralization effect of A₂and A₃were more significant than that of A₁, andthere was no significant difference between A₂and A₃.2.2Group B2.2.1The remineralization effect was0.07470±0.04417in Group B₁,0.10741±0.06489in Group B₂,0.10650±0.06079in Group B₃.2.2.2To compare the remineralization effect between B₁and B₂（p=0.039, p＜0.05）, B₂and B₃（p=0.946, p＞0.05）, B₁and B₃（p=0.038, p＜0.05）. Theremineralization effect of B₂and B₃were more significant than that of B₁, andthere was no significant difference between B₂and B₃.2.3Comparison of the remineralization effect between Group A and Group BTo compare the remineralization effect between A₁and B₁（p=0.000, p＜0.05）,A₂and B₂（p=0.002, p＜0.05）, A₃and B₃（p=0.000, p＜0.05）. Group A wasmore prone to remineralization than Group B.Conclusions: Using traditional Hawley retainer was more prone toremineralization. It could be a good choice to those patients who got enamel demineralization in the fixed application. Besides keeping a good oral hygieneafter debonding, topical fluoride protector application would has asignificantly remineralization effect.