Effect of enamel deproteinization on bonding orthodontic brackets: A systematic review and meta-analysis

Enamel deproteinization using 5.25% sodium hypochlorite (NaOCl) or papain before enamel etching has been proposed to increase shear bond strength (SBS) of orthodontic brackets. Yet, evidence about its efficacy remains unclear.

This systematic review assesses the effects of enamel deproteinization on SBS and the adhesive remnant index (ARI) of orthodontic brackets bonded using different adhesives.

Four databases, PubMed, Cochrane Database of Systematic Reviews, Scopus, and Web of Science™ Core Collection, and gray literature were searched with no limitations up to May 2024.

Randomized studies in vitro.

Study selection, data extraction, and risk of bias assessment were done independently in duplicates. Random-effects meta-analysis of mean differences (MDs) with their 95% confidence intervals (CIs) were conducted, followed by subgroup analysis, sensitivity analysis, and the Grades of Recommendations, Assessment, Development and Evaluation analysis of the evidence quality.

A total of 19 studies (including a total of 1399 extracted premolars) were included in this systematic review. These studies compared pretreatment with enamel deproteinization and bonding with bonding only without deproteinization. Low quality of evidence indicated that enamel deproteinization using 5.25% NaOCl did not have a statistical significance change on SBS (MD = -1.17, 95% CI: -2.35 to 0.02, P = 0.05) and ARI (MD = -0.27, 95% CI: -0.55 to 0.01, P = 0.06). On the other hand, enamel deproteinization using papain significantly increased the SBS (MD = -2.78, 95% CI: -4.49 to - 1.07, P = 0.001) and did not significantly increase the ARI (MD = -0.29, 95% CI: -0.58 to 0.01, P = 0.06). The main limitations of the existing evidence pertained to risk of bias, inconsistency, and imprecision of included studies.

Enamel deproteinization using 5.25% NaOCl showed no significant effects on SBS and ARI, while papain was associated with significantly higher SBS only with no significant effects on the ARI of orthodontic brackets bonded using resin composites or resin-modified glass ionomers.