Comparative impact of manual and electric toothbrushing on acid-eroded enamel

To evaluate and compare the enamel wear resulting from manual and electric toothbrushing following acid erosion, using natural human enamel specimens. The study aimed to quantify both surface tissue loss and subsurface prism alterations.

Twenty-four caries-free extracted human molars were decoronated and sectioned to expose natural buccal enamel surfaces. Samples were divided into two groups (manual vs electric) and subjected to four cycles of citric acid erosion (pH 2.7) followed by controlled brushing (30 strokes per cycle, total 120) using a non-fluoridated toothpaste slurry. Brushing force was standardised to 290-295g. Step height changes were measured via non-contact laser profilometry, and enamel prism alterations were assessed using scanning electron microscopy (SEM). Statistical analysis was performed using Shapiro-Wilk test (normality), two-way ANOVA, and Bonferroni's post hoc test (α = 0.05).

Electric toothbrushes caused significantly greater enamel wear compared to manual brushes across all erosion-abrasion intervals (p < 0.0001). Mean step height increased from 1.38(0.42) µm to 3.65(0.39) µm for manual brushing and from 1.71(0.22) µm to 5.13(0.28) µm for electric brushing. SEM revealed deeper subsurface prism deformation (30-50 µm) in manual samples, whereas electric samples exhibited shallower changes (10-15 µm) with a ∼10 µm interface gap.

Electric toothbrushes resulted in significantly more surface enamel loss on acid-eroded natural teeth compared to manual toothbrushes. The nature of subsurface changes differed by brushing mode, with implications for the mechanical impact of brush types on compromised enamel.

Brushing technique and toothbrush type influence the extent of enamel wear on eroded surfaces. These findings underscore the importance of tailored oral hygiene advice, particularly for individuals with dietary acid exposure or early signs of erosion.