Qualitative and quantitative evaluation of enamel surface roughness and remineralization after interproximal reduction: An in vivo study

Introduction: Interproximal reduction (IPR) damages the caries protective superficial layer of the enamel, making the enamel surface prone to caries because of the increase in surface roughness. Remineralizing solutions can help in preventing these undesirable side effects. Therefore, this study aimed to compare the effect of nanohydroxyapatite (nHAp) and sodium fluoride (NaF) application on enamel remineralization after IPR and to evaluate changes in surface roughness, composition, and microhardness of the treated enamel. Methods: A total of 25 patients with Angle's Class I malocclusion, requiring 4 premolar extractions, were selected and randomly divided into 5 groups (n 5 5). Group 1 served as the control. In group 2, the extraction of premolars was done immediately after IPR, and in group 3, the extraction of premolars was done 3 months after IPR. In group 4, the extraction of premolars was performed 3 months after IPR with weekly application of nHAp serum. In group 5, the extraction of premolars was performed 3 months after IPR, along with once-a-month application of NaF varnish. The proximal reduction of premolars in all the groups was done using Strauss IPR burs (Strauss Diamond Instruments, Palm Coast, Fla). The extracted teeth were sectioned, and the enamel surfaces were subjected to energy-dispersive x-ray spectroscopy to evaluate elemental composition. Vicker's microhardness test was used to evaluate enamel hardness and atomic force microscopy for enamel surface roughness. Descriptive statistics were calculated for the 5 groups using a 1-way analysis of variance, and Tukey's multiple post-hoc test was used for intergroup comparison. Results: Calcium-to-phosphorous ratio, enamel microhardness, and surface roughness were found to be closest to untouched enamel in patients treated with nHAp, followed by patients who were treated with NaF. A lower calcium-to-phosphorous ratio and weakened and roughest enamel surface was seen in teeth, which were extracted immediately after IPR. Conclusions: Among the remineralizing agents tested, nHAp serum can be recommended for better remineralization of enamel surfaces after IPR.