Comparison Between Structural and Compositional Changes of Human Root Surface on Exposure to Different Wavelengths of...

Background Diode lasers are increasingly used as adjuncts in periodontal therapy because of their potential for root surface decontamination and biofilm reduction. However, their effects on the structural and compositional integrity of the root surface depend on the irradiation parameters used. Aim To evaluate and compare the structural and compositional changes in the roots of extracted human single-rooted permanent teeth after diode laser irradiation at 660 nm and 810 nm for 30 and 45 seconds. Materials and methods This in vitro study included 52 extracted human single-rooted permanent teeth, which were divided into four groups (n=13 each): Group 1, 660 nm for 30 seconds; Group 2, 660 nm for 45 seconds; Group 3, 810 nm for 30 seconds; and Group 4, 810 nm for 45 seconds. After laser application, surface roughness was assessed using Ra, Rq, and Rz parameters. Morphological changes were evaluated by scanning electron microscopy (SEM), and elemental composition was analyzed using energy-dispersive X-ray analysis (EDAX). Intergroup comparison of surface roughness was performed using Welch analysis of variance (ANOVA) followed by pairwise post hoc testing. Results Surface roughness increased progressively from Group 1 to Group 4. Mean Ra values ranged from 0.0031±0.0002 µm in Group 1 to 0.0123±0.0014 µm in Group 4. Similar trends were seen for Rq and Rz. Intergroup differences were statistically significant for Ra, Rq, and Rz (p<0.001 for all). Pairwise analysis showed no significant difference between Groups 1 and 2, whereas all other comparisons were significant. EDAX analysis showed increasing carbon and oxygen and decreasing phosphorus and calcium from Group 1 to Group 4. SEM findings also showed progressively greater surface alteration with increasing wavelength and exposure duration. Conclusion Diode laser irradiation produced wavelength- and time-dependent structural and compositional changes on the root surface. The greatest alterations were observed with 810 nm irradiation for 45 seconds, indicating that laser parameters should be selected cautiously to minimize excessive root surface damage.