| ObjectiveIcon Infiltration resin is a new type of permeable material with good penetrating,mechanical,anti-carious and acid-resistant properties.With aesthetic effects,it's mainly used for the treatment of white-spot lesions(WSL),mild or moderate dental fluorosis(DF)and so on.However,the stability of the color,properties and structure of the resin in the human oral environment may be affected by various factors.Previous studies focused mainly on long-term color stability of resin,but there were little studies about the ultrastructure changes of the infiltrated resin under the influence of continuous mechanical factors.This study aims to analyze the abrasive influence of toothbrushing on the ultrastructure of the infiltration resin surface by simulated toothbrushing for different duration of time in vitro,thereby evaluating the long-term effects of infiltration resin.Methods50 orthodontic teeth were completely removed and collected from the Department of Maxillofacial Surgery,Dental Hospital of Tianjin Medical University.Dental operating microscopy(DOM)showed healthy and intact enamel structure.The smooth enamel surfaces of extracted teeth were prepared into pieces of 3 mm*3 mm size,then grinded and polished.Each sample was polished after being treated with Icon infiltration resin in accordance with the specification.2 samples were randomly selected as the control groups and the remaining 50 samples were randomly divided into 5 groups as the experimental groups,with 10 samples in each group.An in vitro study model was established by a vertical universal friction-wear testing machine and artificial saliva containing toothpaste,by which the samples were brushed for half a year,1 year,2 years,3 years,and 5 years respectively.8 samples of each group were used to examine the surfaces of the infiltration resin,and 2 were incised perpendicularly to enamel surface to expose cross sections.The SEM was used to observe the ultrastructure of surface and cross section,measure the percentage of the abrasion area of total area and quantificationally analyze the differences of abrasion of the infiltration resin among each group.Data was analyzed with Kruskal-Wallis H test and Mann-Whitney test,with the level of significance set at ?=0.05.ResultsThe abrasion areas of each grade and total abrasion areas were different among 5 experimental groups,and abrasion manifestations of resin in different stage were varied.SEM observations were as follows: the infiltration resin surface of control groups was relatively homogeneous and flat.Simulated toothbrushing for half a year had no significant effect on resin surface,except that the surface was slightly rough,accounting for about 2.5% of the total area.After 1 year,deep pit-like defects(6.0% of total area)were found.After 2 years,except for deep pit-like defects,intermittent fissures appeared,accounting for about 17.0%,suggesting that there are cracks between resin and enamel layer.After 3 years,a wider range of pit-like defects and fissures could be seen on the resin surface,reaching 17.1% of the total area.After 5 years,the surface was very rough and disordered,with disintegration and exfoliation of resin,taking up 19.9% of the total area.Compared with previous group,total abrasion area of the resin increased significantly after 1 year and 2 years of simulated brushing(P<0.05).After 3 years,only fissures increased(P < 0.05),while total area showed no significant difference(P > 0.05).After 5 years,the area of exfoliation increased(P < 0.05),while there was no significant difference in total abrasion area(P > 0.05).SEM observations of cross section showed that infiltration resin could infiltrate into enamel,and further confirmed that the infiltration resin layer covering the enamel surface gradually became thinner due to simulated toothbrushing.ConclusionsThis study presented that simulated toothbrushing could destroy the surface structure of infiltration resin,and the damage extent of the abrasion became more obvious as time increased.Enamel rod might be a weak area of the bonding between enamel and infiltration resin.However,after 5 years of simulated brushing,the area of damaged integrity accounted for 6.9% of the total area,the other resin still had a good combination with enamel surface,proving that the infiltration resin had a relatively stable clinical treatment effect during a long time.However,the condition of oral cavity is more complicated,follow-up annual is necessary after treatment.Infiltration resin could be selectively reapplied to the abrasion area after 3-5 years. |
PDF Full Text Request