Evaluation of enamel surface after interproximal reduction using different methods, with and without polishing: an in vitro study

To evaluate the changes in enamel surface roughness and elemental concentrations following interproximal reduction (IPR), with and without polishing, in comparison with enamel without stripping. Selected premolars were randomly divided into a control group and four experimental groups; Group A (control): enamel without stripping, Group B: IPR with diamond bur, Group C: IPR with diamond disc, Group D: IPR with manual strip, Group E: IPR with mechanical oscillating strip. Each experimental group was divided into two subgroups where one subgroup was also polished with fine Sof-Lex discs. A total of 108 enamel samples (12 samples/subgroup and 12 samples for the control group) were used. Enamel was evaluated with atomic force microscope, energy-dispersive x-ray spectroscopy, and scanning electron microscope. The IPR produced higher average roughness (nm) in all groups compared with the enamel without stripping which measured 79.5 ± 17.4 nm. The only significant difference among the experimental groups was the higher roughness in the disc group compared to the oscillating strip group, p = 0.035. Polishing produced smoother enamel surfaces in all groups.The Ca/P weight (%) was 1.68 ± 0.45% when the enamel was not stripped and the ratio ranged from 2.03 ± 0.69% to 2.58 ± 0.47% in the IPR/IPR+polishing groups. Scanning electron microscope confirmed an increase in surface roughness following IPR with subsequent improvement after polishing. The IPR increased enamel surface roughness and affected the elements weight (%) and atomic (%). Polishing improved the surface quality. The IPR with oscillating strip followed by polishing with Sof-Lex strip produced the most favorable results.