Effect of diode laser power settings on calcium loss in acid-eroded dentin: an in-vitro analysis

This in-vitro investigation aimed to evaluate how varying power settings of a low-intensity diode laser (λ = 808 nm) influence calcium loss from dentin surfaces subjected to dental erosion (DE) produced by standardized 1% hydrochloric acid. Fifty dentin specimens (4 × 4 × 2 mm³) were sectioned from the roots of fifty sound, non-carious premolars using a precision cutting machine. Each specimen was embedded in self-curing acrylic blocks to aid handling and subsequently flattened with water-cooled silicon carbide abrasive papers. Samples were randomly allocated into five groups (n = 10) according to diode laser output and exposure duration: Group 1-1 W/30 s; Group 2-1 W/60 s; Group 3-500 mW/30 s; Group 4-500 mW/60 s; Group 5-control (no laser). Following irradiation, all specimens were challenged with 10 μl of 1.0 M HCl for 5 min, rinsed with deionized water, dried with absorbent paper, and analyzed for calcium release using atomic absorption spectrometry. Data were processed in SPSS version 26.0. One-way ANOVA was employed to determine statistical significance (CI = 95%, p < 0.05), and intergroup comparisons were performed with the Kamskove test. Laser irradiation significantly reduced calcium dissolution compared to the control (45.199 ± 1.058 mg/L). Measured calcium levels were 20.222 ± 0.641 mg/L (1 W/30 s), 12.517 ± 0.606 mg/L (1 W/60 s), 34.372 ± 1.361 mg/L (500 mW/30 s), and 25.377 ± 1.268 mg/L (500 mW/60 s), with p = 0.000. The respective reductions relative to control were 55.3%, 72.3%, 23.9%, and 43.8%. Application of an 808-nm diode laser demonstrated a protective effect against acid-induced calcium loss in dentin. The 1 W power for 60 s provided the greatest resistance to erosion, followed by 1 W for 30 s, then 500 mW treatments.