Objective characterization of dental occlusal and fissure morphologies: Method development and exploratory analysis.

OBJECTIVE: To develop clinically applicable methods to characterize occlusal topography and assess possible associations between morphology and caries incidence and development. DESIGN: In this retrospective clinical study, we evaluated caries presence and severity pre- and post-orthodontic treatment for first molars of 147 patients (384 teeth). These teeth were previously scanned using a clinical intraoral scanner, and the obtained digital elevation models were used to 1) analyze the 3D occlusal surface parameters (n = 384) and 2) quantitatively characterize the mandibular molars' (n = 166) fissure patterns using three novel methods. Pearson correlation coefficients were calculated to evaluate the associations among the measurements, and presence/severity of caries pre- and post-treatment were assessed using generalized linear mixed-effects models. RESULTS: Robust quantitative fissure characterizations were developed, and reliable occlusal surface parameters were obtained. In the studied population, none of the parametric measurements (Slope: p = 0.62 for presence, p = 0.96 for severity; Relief Index (RFI): p = 0.36, p = 0.84; Orientation Patch Count rotated (OPCr): p = 0.48, p = 0.13; Dirichlet Normal Energy (DNE): p = 0.91, p = 0.15) or the fissure morphological measurements (Mesial Angle: p = 0.43; Distal Angle: p = 0.86; Average Angle: p = 0.52; Area Difference: p = 0.83; Percent Fissure: p = 0.68) were found to be significantly associated with caries status or severity. CONCLUSION: Despite the lack of correlation in the limited studied sample, the tools developed to characterize occlusal surface topography and fissure morphology have the potential to be used in more comprehensive clinical evaluations.

Impact of dentifrice abrasivity and remineralization time on erosive tooth wear in vitro.

PURPOSE: To investigate the in vitro effects of simulated dentifrice slurry abrasivity (L-low, M-medium and H-high) and remineralization time (0, 30, 60 and 120 minutes) on erosive tooth wear. METHODS: Enamel and root dentin specimens were prepared from bovine incisors (n= 8) and submitted to a cycling protocol including erosion, remineralization at the test times, and brushing with each of the tested slurries, for 5 days. Dental surface loss (SL) was determined by optical profilometry. Data was analyzed using mixed-model ANOVA and Fisher's PLSD tests (alpha= 0.05). RESULTS: SL generally increased along with the increase in slurry abrasive level, with significance dependent upon the specific substrate and remineralization times. H showed the highest SL on both enamel and dentin; remineralization for 30 minutes reduced SL significantly (P< 0.05), but only for enamel. M showed intermediate SL values, with remineralization benefit clearly seen only after 120 minutes of remineralization (P< 0.05). L caused the least SL for both enamel and dentin, which was further reduced after remineralization for 120 and 30 minutes, respectively (both P< 0.05). Overall, root dentin had significantly higher SL than enamel. Less abrasive dentifrice slurries were able to reduce toothbrushing abrasion on both enamel and root dentin. This protection was enhanced by remineralization for all abrasive levels on enamel, but only for L on root dentin. CLINICAL SIGNIFICANCE: High-risk erosion patients should avoid highly abrasive toothpastes, as remineralization can only partially compensate for their deleterious effects on eroded dental surfaces. Lower abrasive toothpastes are recommended.