Resistance of bonded premolars to four artificial ageing models post enamel conditioning with a novel calcium-phosphate paste.

Ai Ibrahim,Vp Thompson,S Deb,Nr Al-Hasani

doi:10.4317/jced.56764

Ai Ibrahim, Vp Thompson + Show 2 more

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https://doi.org/10.4317/jced.56764

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Abstract

BackgroundThis in vitro study compares a novel calcium-phosphate etchant paste to conventional 37% phosphoric acid gel for bonding metal and ceramic brackets by evaluating the shear bond strength, remnant adhesive and enamel damage following water storage, acid challenge and fatigue loading. Material and MethodsMetal and ceramic brackets were bonded to 240 extracted human premolars using two enamel conditioning protocols: conventional 37% phosphoric acid (PA) gel (control), and an acidic calcium-phosphate (CaP) paste. The CaP paste was prepared from β-tricalcium phosphate and monocalcium phosphate monohydrate powders mixed with 37% phosphoric acid solution, and the resulting phase was confirmed using FTIR. The bonded premolars were exposed to four artificial ageing models to examine the shear bond strength (SBS), adhesive remnant index (ARI score), with stereomicroscopic evaluation of enamel damage. ResultsMetal and ceramic control subgroups yielded significantly higher (p < 0.05) SBS (17.1-31.8 MPa) than the CaP subgroups (11.4-23.8 MPa) post all artificial ageing protocols, coupled with higher ARI scores and evidence of enamel damage. In contrast, the CaP subgroups survived all artificial ageing tests by maintaining adequate SBS for clinical performance, with the advantages of leaving unblemished enamel surface and bracket failures at the enamel-adhesive interface. ConclusionsEnamel conditioning with acidic CaP pastes attained adequate bond strengths with no or minimal adhesive residue and enamel damage, suggesting a suitable alternative to the conventional PA gel for orthodontic bonding. Key words:Enamel etching, calcium phosphate, bracket bond strength, adhesive residue, enamel damage.

Highlights

Conventional orthodontic bracket bonding techniques involve enamel pre-treatment with 37% phosphoric acid (PA) gel to ensure secure attachment of the bracket to the enamel surface
Alternative enamel conditioning methods such as laser etching and the use of self-etch primers resulted in bracket bond strengths suitable for clinical performance; could not eliminate enamel damage and the amount of remnant adhesive left on tooth surface [2,4]
Etchant pastes made of calcium-phosphate (CaP) powders mixed with 37% phosphoric acid were developed for the first time to simultaneously etch and re-mineralize the enamel surface before bracket bonding [5]

Summary

Introduction

Conventional orthodontic bracket bonding techniques involve enamel pre-treatment with 37% PA gel to ensure secure attachment of the bracket to the enamel surface. Etchant pastes made of calcium-phosphate (CaP) powders mixed with 37% phosphoric acid were developed for the first time to simultaneously etch and re-mineralize the enamel surface before bracket bonding [5] This approach facilitated the preferable bracket debonding failure at the enamel-adhesive interface, with no or minimal adhesive remnants after debonding, saving chair-side time and cost at the post debonding clean-up stage. The artificial ageing models involve separate exposure to prolonged acidic challenge, water storage, and 5000 fatigue cyclic loading This in vitro study compares a novel calcium-phosphate etchant paste to conventional 37% phosphoric acid gel for bonding metal and ceramic brackets by evaluating the shear bond strength, remnant adhesive and enamel damage following water storage, acid challenge and fatigue loading. Conclusions: Enamel conditioning with acidic CaP pastes attained adequate bond strengths with no or minimal adhesive residue and enamel damage, suggesting a suitable alternative to the conventional PA gel for orthodontic bonding

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