The effect of Chlorohexidine, Er:YAG Laser and Diode Laser 980 nm as Dental Cavity Disinfectants on Dentine Morphology and Microleakage of Composite Restoration: An In Vitro Study

Introduction Residual microorganisms may remain even after thorough mechanical cavity preparation, leading to secondary caries. Additionally, the smear layer generated during this process can impair the adhesion between composite resin and dentine and limit the penetration of disinfectants into dentinal tubules. This study aimed to compare the effects of 2% chlorhexidine (CHX), 980 nm diode laser, and Er:YAG laser as cavity disinfectants on dentine morphology, mineral content, and microleakage of composite restorations. Materials and Methods Forty extracted sound human primary molars were randomly assigned to four groups (n = 10): Group I (negative control, no disinfection), Group II (2% CHX application), Group III (980 nm diode laser, 1 W, continuous wave), and Group IV (Er:YAG laser, 1.2 W). Dentine morphology and restoration microleakage were examined via Scanning Electron Microscopy: (SEM), while mineral content was evaluated using Energy-Dispersive X-ray Spectroscopy (EDX). Results SEM analysis showed that CHX (Group II) left smear layer residues with narrowed tubules, while the diode laser (Group III) partially removed the smear layer. Er:YAG laser (Group IV) resulted in complete smear layer removal, wider tubules. EDX revealed significantly higher mineral content in Group IV compared to Groups II and group III (p < 0.001), with no significant difference between Groups II and III. Microleakage was highest in the control group and lowest in the Er:YAG group (p < 0.001). Conclusion The Er:YAG laser showed superior outcomes in improving dentine morphology, increasing mineral content, and minimizing microleakage, making it the most effective disinfectant tested.