Debonding Characteristic and Survival Probability of Adhesive Flash-Free Ceramic Orthodontic Brackets Following pH Cycling

TL;DR

This study found that flash-free adhesive-precoated ceramic orthodontic brackets have higher bond strength and better survival rates compared to noncoated brackets under different pH conditions.

Contribution

The study introduces flash-free adhesive-precoated ceramic brackets as a novel solution with improved bond strength and survival probability in orthodontic applications.

Findings

Flash-free brackets showed significantly higher shear bond strength (SBS) in both artificial saliva and pH cycling conditions.

Flash-free brackets had higher survival probability (95%) compared to noncoated brackets in both storage medium groups.

Noncoated brackets had acceptable SBS results but lower survival probability compared to flash-free brackets.

Abstract

Objectives
 Orthodontic bracket bond failure is an obstacle in clinical orthodontics. This study investigated the influence of pH cycling on the shear bond strength (SBS), adhesive remnant index (ARI), and survival probability of adhesive-precoated flash-free ceramic brackets.

Materials and Methods
 Forty mandibular premolars were randomly divided into two groups (
n
 = 20): C: noncoated orthodontic brackets, and F: flash-free adhesive-precoated orthodontic brackets. Each group was subdivided into two subgroups according to storage medium solutions (
n
 = 10): in subgroup AS, specimens were immersed in artificial saliva for 24 hours, and in Subgroup ASL, specimens were recycled between a demineralizing solution and an artificial saliva for 42 days. Within each subgroup, specimens were subjected to SBS and ARI testing. SBS data were analyzed using one-way ANOVA (analysis of variance) and Tukey's post-hoc test. Weibull analysis was performed on the SBS data to determine the characteristic SBS and their survival probabilities.

Results
 Flash-free adhesive-precoated brackets had higher significant (
p
 < 0.001) SBS values in both the AS group (17.74 ± 1.74 MPa) and the ASL group (12.61 ± 1.40 MPa) compared with the noncoated bracket (10.67 ± 1.55 and 7.89 ± 1.39 MPa, respectively). The ARI scores for the noncoated brackets in the AS group were 70% occurrence for score 1, while 90% for score 1 in the ASL group. For the flash-free precoated brackets, ARI scores were 70% occurrence for score 2 in the AS group, while 80% for score 2 in the ASL group. Flash-free brackets had higher SBS in both AS and ASL groups (14.07 and 9.76 MPa, respectively), at 95% survival probability.

Conclusion
 Flash-free orthodontic brackets performed better in terms of significantly higher bond strength and higher ARI scores. Meanwhile, noncoated brackets revealed acceptable SBS results in both storage medium groups. Flash-free brackets showed higher survival than the noncoated brackets in both storage medium groups at 90% survival probability.

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