Nano-composite versus conventional light-cure composite: A comparative assessment of orthodontic bracket bond failure rates

Objective: To compare the bond failure rates of orthodontic brackets bonded with nano-composite and conventional light-cure composite using a fourth-generation curing unit. Method: The randomised double-blind clinical trial was conducted at the Department of Orthodontics, Foundation University College of Dentistry and Hospital, Islamabad, Pakistan, from January to December 2022, and comprised patients aged >12 years requiring fixed orthodontic treatment. They were randomly assigned to two groups. Group A comprised patients bonded with a conventional composite, while Group B comprised patients bonded with a nano-composite. Orthodontic brackets were bonded and followed for a period of six months. Bond failures were evaluated at three and six months. Data was analysed using SPSS 26. Results: Of the 50 patients with mean age 22.9±5.0 years (range: 12-35 years), 31(62%) were female and 19(38%) were male. There were 25(50%) patients in each group. A total of 1,000 orthodontic brackets were evaluated; 500(50%) in each group. A total of 18(1.8%) bracket failures were observed; 11(2.2%) in Group A, and 7(1.4%) in Group B (p=0.61). The highest failure rate was observed in second premolars 12(6%), while central incisors exhibited the lowest rate 2(1%). Early failure peaks were noted in Group A during the second (p=0.04) and fourth (p=0.02) months. No significant intergroup or intragroup differences were detected at either of the two follow-ups (p>0.05). Conclusion: Both the composites demonstrated clinically acceptable bond failure rates (<5%). Although the nano-composite showed a numerically lower failure rate, the difference was not statistically significant. Trial registration: ClinicalTrials.gov Identifier: NCT05644860. Key Words: Composite resin, Nano-composite, Orthodontic brackets, Hybrid composite.