Lesão cariosa proximal de esmalte: análise de desmineralização e cavitação em áreas inacessíveis ao exame visual direto em molares decíduos

Abstract

The establishment of the proximal contact area creates areas inaccessible to direct visual examination, rendering the most favorable conditions for the accumulation of cariogenic biofilm and initiation of the proximal natural enamel caries lesion (PNEC) localized cervically to the contact area. It is believed that the onset of cavitation on the proximal surface also occurs cervically to the proximal contact area, but scientific evidence is lacking. Considering the importance of the site for the onset of cavitation in PNEC for secondary preventive interventions, this study aimed at analyzing inaccessible areas to direct visual examination on proximal surfaces (contact area, IIB; and cervically to the contact area, IIIB) of deciduous molars with regard to the distribution of enamel demineralization, quantification of demineralized enamel volume, and distribution of cavitation in PNEC. Methodology: This is an in vitro, transversal, and observational study. Proximal surfaces of exfoliated deciduous molars (n = 37) presenting active contact area (no biofilm contact area facet but surrounded by biofilm) and PNEC on the inaccessible areas. Biofilm and PNEC (sound or carious with ICDAS scores 1-3) on the anatomical areas of the proximal surfaces were detected under stereomicroscopy by a single examiner calibrated with regard to the scoring systems of both biofilm (Kappa of 0.899) and caries (Kappa of 0.799) in relation to cervicoocclusal divisions of the proximal surface (Area I, occlusal to IIB; Area II, including IIB; and Area III, cervical to IIB). Then, all faces were analyzed by computerized 3D microtomography (microCT) for the detection of PNEC, quantification of demineralized enamel volume, and detection of cavities (depth > 90 µm) in PNEC in relation to the selected anatomical areas (IIB, IIIB, and the occlusal and cervical halves of IIB). Results: Regarding the cervico-occlusal divisions, Area I presented: (i) a lower amount of biofilm than the other areas (area II: p < 0.00001; Wilcoxon; Hedge G 0.756; power = 99,01%; area III p < 0.00001; Wilcoxon; Hedge G 0.890; power < 99,99%), while the other areas did not differ significantly; and (ii) no PNEC, and the other areas presented much higher frequencies of PNEC (area II: p < 0.00001; Z Test ; Cohen H 0.756, power < 99,99%; area III p < 0.00001; Z Test, Cohen H 1,794; power < 99,99%), but the later areas did differ much (I e III p=0,1790; Z Test, Cohen H 0,3123; power = 26,88%). Compared to IIB, area IIIB presented: (i) a higher frequency of demineralized enamel with a medium effect size (p <0.01, Z test, Cohen H of 0.649, 95% CI of 1.104 to 0.193 and power of 80%); (ii) higher demineralized enamel volume, with a large effect size (p = 0.002, Wilcoxon, Hedge G of 0.816, 95% CI 0.543 to 1.087, and 87% power). There was no cavitated PNEC on the IIIB area, and all cavitatied PNEC were located on the IIIB area, with a large effect size of the difference of proportions of cavitated PNEC (p <0.0001, Z test Cohen's H of 1.459, 95% CI of 1.003 to 1.915 and power> 99.9%). When comparing the occlusal and cervical halves of the IIB area, the enamel layer of the cervical half showed a much larger demineralized enamel volume (p = 0.0003, Wilcoxon, Hedge G of 1.219, 95% CI of 0.709 to 1.730 and power of 95 %) and a very high proportion (90%) of cavities (p <0.001, Z test, Cohen's H of 1,251, 95% CI of 0.787 to 1.714, power = 99.73%). Conclusion: Although the area IIIB presented the highest frequency of PNEC and largest demineralized enamel volume in the enamel layer, cavitated PNEC were found only in the IIB area, more specifically in the cervical half of the later.