Background: Inadvertent traumatic lesions of anterior teeth with avulsion are managed by delayed replantation. Poor root surface conditioning, root resorption and non-viable fibroblasts are factors responsible for failure. Purpose: To evaluate effects of Er:YAG laser application through encouraging adhesion and attachment of human periodontal ligament fibroblasts (PDLF) to intact root surfaces imitating delayed replantation cases. Methodology: Twenty four human healthy single-rooted premolars were collected. Four teeth were used for PDLF, whereas remained twenty teeth (provide 40 root slices) used for PDLF cell density & morphology. Each root was soaked in 5.25% NaOCl. Two groups (n=20 slices/each) were planned as follows: I; Control (untreated), II; Er:YAG laser irradiation (4mm distance, 40 mJ/pulse, under coolant). Following incubation, PDLF cell density and morphology were investigated by SEM. Statistical analysis was done comparing means and standard deviations. Results: The two groups showed a noticeable increase in cultured PDLF following incubation. Regarding cell density, attached PDLF were significantly lower in untreated controls (37.5±10.2) (p=0.000 <0.05) in negative empty &/or light cellular areas, compared to laser-irradiated group (67.0±8.7) that showed intermediate &/or heavy cellular areas. Regarding cell morphology, controls showed round &/or oval appearance with less lamellipodia, whereas Er:YAGlaser group showed flat morphology with evident long cytoplasmic processes.

Conclusions: Er:YAG laser showed a good biocompatibility of PDLF attachment on root surface slices imitating delayed replantation. Thus, Er:YAG laser can act as a promising conditioning tools for such roots & recommended to be applied in clinical situations.

Keywords: Er:YAG laser, root conditioning, human PDLF, delayed replantation

Prof. Belal MH, BDS, MSc (Egypt), PhD (Japan) is clinical professor, Periodontology, Oral Medicine & Oral Diagnosis, Faculty of Dentistry; Damanhour University; Egypt. His Ph.D. degree from Tanta University, Egypt; & Tokyo Medical & Dental University, Tokyo, Japan (2003~2005). He works as Editorial Board Member, Reviewer in International Journals; & reviewer for supreme council of Egyptian universities. Heworked as general supervisor for post graduate students, Faculty of Dentistry, Kafr-Elsheikh University, Egypt (2023); & head of Medical committee, Damanhour University, Egypt (2020-2023). He is member of Egyptian Dental Association. He published many research articles in several international & local Journals