Influence of Er:YAG Laser Dentin Conditioning with End-Firing Versus Side-Firing Tips on Human Dental Pulp–Derived Cell Viability

Introduction: Dentin surface conditioning plays a key role in regenerative endodontics by influencing stem cell viability. Although ethylenediaminetetraacetic acid (EDTA) effectively removes the smear layer, residual chelating agents may compromise cytocompatibility. Er:YAG (erbium-doped yttrium aluminum garnet) laser conditioning offers an alternative approach with minimal chemical residue, and laser tip geometry may further influence biological outcomes. This study evaluated the cytocompatibility of Er:YAG laser dentin conditioning using End firing sapphire and side-firing tips by assessing human dental pulp – derived cell viability. Methods: Thirty-six single-rooted human teeth were decoronated and instrumented to ProTaper F4. Specimens were randomly allocated to four groups ( n = 9): untreated control, Er:YAG laser with sapphire tip, Er:YAG laser with side-firing tip, and 17% EDTA. Following dentin conditioning, roots were longitudinally split to expose the canal wall, and human dental pulp–derived cells (1 × 10 4 cells/specimen) were seeded onto the treated surfaces. Cell viability, as an indirect indicator of cytocompatibility, was assessed using the MTT assay at Days 1, 4, and 7. Data were analyzed using one-way analysis of variance with Bonferroni post hoc tests (α = 0.05). Results: At all time points, the side-firing Er:YAG group demonstrated the highest cell viability, followed by the End firing sapphire-tip laser group. EDTA-conditioned dentin showed significantly lower viability, while the control group maintained baseline viability. Differences between groups became more pronounced over time. Conclusions: Er:YAG laser dentin conditioning enhanced human dental pulp–derived cell viability compared with EDTA, with the side-firing tip yielding the most favorable results. Side-firing Er:YAG tips may therefore provide a more cytocompatible dentin surface for regenerative endodontic applications.