Lesões cervicais não cariosas: métodos diagnósticos, caracterização morfológica e desempenho da interface restauradora

Abstract

Non-carious cervical lesions (NCCLs) remain a diagnostic, therapeutic, and prognostic challenge in clinical practice. This multimethodological study, comprising four chapters (I–IV), investigated NCCLs through an integrated approach by evaluating: (I) the diagnostic accuracy of Optical Coherence Tomography (OCT) combined with a contrast solution and the North Carolina Dentin Sclerosis Index (NCDSI) for identifying sclerotic dentin in NCCLs; (II) the effect of aluminum oxide air abrasion on superficial dentin sclerosis, dentin surface topography, and the adhesive performance of a universal adhesive system in NCCLs classified by OCT and the NCDSI; (III) the definition of critical cervical dentin (CCD), a novel anatomical region in NCCLs, investigation of its relationship with remaining dentin thickness (RDT), and evaluation of the diagnostic performance of predictors based on CCD involvement and lesion depth for detecting critical RDT (≤1.0 mm), a criterion for restorative intervention; and (IV) the analysis of dentin histomorphological characteristics and factors associated with the development and progression of NCCLs. In Chapter I, thirty natural NCCLs (90 regions of interest) were evaluated using OCT combined with a contrast solution and the NCDSI, with scanning electron microscopy serving as the reference standard. Diagnostic performance metrics were calculated with 95% confidence intervals. In Chapter II, forty-eight premolars with natural NCCLs were allocated according to dentin classification by OCT and the NCDSI into aluminum oxide air abrasion and control groups. Stereomicroscopy, OCT, micro-computed tomography, three-dimensional optical profilometry, microtensile bond strength testing, nanoleakage, and micro- Raman spectroscopy were performed. In Chapter III, 139 natural NCCLs were analyzed by micro-computed tomography to measure lesion depth, lesion height, depth-to-height ratio, remaining dentin thickness, and CCD location. Linear regression, risk ratios, and diagnostic performance analyses were used to evaluate restorative predictors based on clinical lesion depth and CCD involvement, including analyses stratified according to lesion morphology. In Chapter IV, histomorphological analyses investigated dentinal tubules, structural crystallite bands, and dentin characteristics associated with the development and severity of NCCLs. In Chapter I, the dichotomous OCT classification demonstrated high diagnostic accuracy for identifying sclerotic dentin (0.86; 95% CI: 0.77–0.92), with a sensitivity of 0.81 and specificity of 0.94. The four-level OCT index showed lower diagnostic performance, with an accuracy of 0.70 (95% CI: 0.51–0.85). The NCDSI exhibited poor diagnostic accuracy (AUC = 0.47; 95% CI: 0.27–0.67), low sensitivity and specificity, and no significant correlation with the reference standard (p = 0.65). In Chapter II, air abrasion did not significantly alter dentin classification by either diagnostic method (p > 0.05), but it produced superficial dentin removal, with a mean volumetric loss of 0.33 mm³, a mean thickness reduction of 34 μm, and a significant increase in surface roughness (p < 0.001). Adhesive performance was substrate- dependent, with improved bond strength in OCT-classified sclerotic dentin and reduced bond strength in non-sclerotic dentin. No significant differences in nanoleakage were observed among the groups (p > 0.05). In Chapter III, each 1- mm increase in lesion depth reduced RDT by 0.637 mm. The CCD concentrated the highest frequency of the lowest RDT values, critical RDT (≤1.0 mm), and maximum lesion depth. Involvement of the inner half of the CCD and a clinical probing depth ≥1.5 mm demonstrated good diagnostic performance for identifying critical RDT in lesions ≤2.5 mm in height; however, in taller lesions, diagnostic performance varied according to the tomographic profile. In Chapter IV, histomorphological analyses demonstrated that dentinal tubule-related alterations, structural crystallite bands, and dentin characteristics were associated with the progression, orientation, and severity of NCCLs, suggesting that histomorphological features and associated etiological factors directly influence the wear pattern of these lesions. In conclusion, OCT demonstrated high diagnostic accuracy for dentin classification in NCCLs, outperforming the NCDSI in identifying sclerotic dentin. Air abrasion produced superficial modifications capable of influencing adhesive performance according to the dentin substrate, without significant removal of the superficial sclerotic layer. The CCD concentrated the lowest RDT values, and the need for restorative treatment may be determined by a clinical probing depth ≥1.5 mm or by CCD involvement in lesions ≤2.5 mm in height; for taller lesions, tomographic evaluation is recommended. Furthermore, dentin histomorphological characteristics and associated etiological factors appear to directly influence the formation and progression of NCCLs.