The Efficacy of Erbium-Ion, Diode, and CO2 Lasers in Debonding Attachments Used During Overlay Orthodontic Treatment and the Risk of Hard Tooth Tissue Damage Compared to Traditional Methods—An In Vitro Study

Objective: This in vitro study evaluated the effectiveness of three laser systems—diode, CO2, and Er:YAG—for debonding composite attachments used in aligner orthodontic therapy. Materials and Methods: Fifty extracted human premolars with composite attachments were divided into five groups (n = 10): control, RT (rotary tools), diode laser (980 nm, irradiance was 4811 W/cm2), CO2 laser (10.6 µm, irradiance 1531 W/cm2), and Er:YAG laser (2940 nm, irradiance 471.7 W/cm2). Shear bond strength (SBS) testing measured debonding forces. Enamel surface changes were evaluated using micro-CT, optical profilometry, and stereomicroscopy. The Adhesive Remnant Index (ARI) assessed residual bonding material. Results: Laser treatment increased enamel roughness (p < 0.05). Er:YAG laser caused the highest roughness (Sa = 2.03 µm) and up to 0.17 mm enamel loss but left minimal adhesive remnants and no fractures. Diode laser preserved surface smoothness with moderate bond weakening. CO2 laser had intermediate effects. RT showed the highest SBS but resulted in greater enamel alteration. SBS was significantly reduced in the laser groups, lowest for Er:YAG (81.7 ± 45.5 MPa vs. control 196.2 ± 75.3 MPa). ARI indicated better adhesive removal in the laser-treated groups, with Er:YAG showing the highest percentage of clean enamel surfaces (67% vs. 25%). Conclusions: Er:YAG demonstrated the best balance between effective debonding and enamel preservation. Diode and CO2 lasers also offer viable alternatives to rotary tools. Further clinical studies are recommended.