Acidic/Abrasive Challenges on Non-Carious Cervical Lesions: Formation, Progression, and Morphology

Objectives: While the impact of toothpaste abrasivity and toothbrushing abrasion on non-carious cervical lesions (NCCLs) is well-documented, the effect of acid challenges on their initiation, progression and morphology remains understudied. This in vitro investigation assessed how frequency of erosive challenges and duration of toothbrushing abrasion influenced NCCLs development. Additionally, we sought to compare the morphology and internal angles of lesions formed under the test protocols.
Methods: Experimental units were prepared using extracted human premolars and randomly assigned to four erosive-abrasive test protocols (n=16): A. No acid exposure (negative control), B. acid exposure every 2500, C. 5000 and D. 15000 brushing strokes (STK). All groups were brushed for a total of 55000 STK. Three-dimension digital images of the teeth were captured at baseline and after 15000, 35000 and 55000 STK, using an intraoral scanner (TRIOS4, 3Shape). A software (WearCompare, Leeds Digital Dentistry) was used to analyze volumetric tooth loss (mm³) by superimposition followed by subtraction analysis. Lesion angle was calculated (ImageJ, NIH) and morphology visually classified by a single examiner. Data were analyzed using ANOVA and Fisher’s Exact tests adopting two-sided 5% significance level.
Results: Overall, no difference in tooth loss was observed among the different frequencies of exposure (p>0.05). Tooth loss increased with STK, for each erosive-abrasive test protocols (p<0.001). Exposure to acid significantly increased tooth loss (p<0.001), regardless of brushing interval (p<0.001). Control had significantly sharper lesion angle (59°) than all acid-exposed groups (~145°) (p<0.001), and significantly different lesion shape with 94% wedge-shaped lesions versus 0%, respectively (p<0.001). Exposure to acid was associated to presence of more striated lesions.
Conclusions: Simulated NCCLs developed and progressed differently and more rapidly in the presence of acidic challenges, regardless of their frequency. Exposure to acid impacted the morphology of the lesion.