Enamel Deproteinization with Sodium Hypochlorite: Effects on Ceramic Bracket Bond Strength

Area of Science:

• Dental Materials Science
• Orthodontics
• Biomaterials Engineering

Background:

• Achieving durable bonds between ceramic orthodontic brackets and dental enamel is crucial for effective treatment.
• Sodium hypochlorite (NaOCl) is sometimes used in dental procedures, but its effect on bracket bonding efficiency is not fully understood.
• Evaluating different bonding agents and protocols is essential for optimizing clinical outcomes.

Purpose of the Study:

• To investigate the impact of varying sodium hypochlorite (NaOCl) concentrations on the shear bond strength (SBS) of ceramic brackets bonded to enamel.
• To compare the efficacy of three different bonding systems (primer + Transbond XT, Optibond S + Transbond XT, and Optibond S + Orthocem) under different NaOCl concentrations.
• To analyze the surface morphology of enamel and the bonding interface using scanning electron microscopy.

Main Methods:

• Ninety bovine incisors were bonded with ceramic brackets using three adhesive systems and three NaOCl concentrations (0%, 2.5%, 5.25%), creating nine experimental groups.
• Shear bond strength (SBS) was measured using a universal testing machine.
• Enamel and interface surface morphology were examined via scanning electron microscopy (SEM).
• Statistical analysis included Kruskal-Wallis, Dunn's tests, and generalized linear models.

Main Results:

• No significant difference in SBS was found between different NaOCl concentrations across all bonding protocols (p>0.05).
• The Optibond S + Orthocem (OS+OC) group consistently exhibited the lowest bond strength values.
• The Optibond S + Transbond XT with 5.25% NaOCl showed significantly higher bond strength than with 2.5% NaOCl (p<0.05).
• SEM analysis indicated alterations in enamel etching patterns with NaOCl application.

Conclusions:

• Pre-application of sodium hypochlorite (NaOCl) at tested concentrations does not enhance the bond strength of ceramic brackets to dental enamel.
• The Optibond S + Orthocem (OS+OC) bonding protocol is not recommended for use with fixed ceramic orthodontic appliances due to low bond strength.
• Clinical protocols should consider the adhesive system's inherent properties over NaOCl application for optimal ceramic bracket bonding.