Photosensitization of lithium di-silicate ceramic by Er, Cr: YSGG and fractional carbon dioxide laser bonded to orthodontic bracket

Abstract

Aim: To evaluate the shear bond strength (SBS) and modes of lithium disilicate ceramics (LDC) photosensitized by Er,Cr:YSGG (ECL) and fractional carbon dioxide (CO₂) laser bonded to metallic bracket compared to traditional conditioning methods.

Material and method: Fifty LDC discs were polished and randomly allocated into 5 groups (n = 10) each. Group 1 were photosensitized with ECL + Silane (S). Group 2 were irradiated using CO₂ laser + S. In group 3 LDC discs were treated with aluminium trioxide (Al₂O₃) air abrasion (AA). Moreover, samples in group 4 and 5 were conditioned with Hydrofluoric acid (HFA)+ S (Control) and Self-Etch Glass Ceramic Primer (SEGCP). Following conditioning regimen fifty maxillary central incisor brackets were pasted on LDC using adhesive material. SBS testing was performed by mounting the specimens on a universal testing machine. After debonding, sheared surface was examined under stereomicroscope to classify failure mode using adhesive remnant index (ARI). Mean and standard deviation (SD) were compared by analysis of variance (ANOVA) and Tukey multiple comparison test at a significance level of p = 0.05.

Results: Among the conditioning groups the highest SBS values were presented by HFA + S (21.08 ± 1.06). The lowest SBS values were displayed by AA Al₂O₃ (12.61 ± 0.45). SBS of samples conditioned with SEGCP showed significant difference amongst all experimental groups (16.76 ± 0.81).

Conclusion: LDC photosensitized with CO₂ and ECL has a potential to be recommended in clinical settings alternate to HFA + S when bonded to metallic bracket.

Keywords: Er,Cr:YSGG photosensitization; Fractional carbon dioxide laser; Hydrofluoric acid; Lithium disilicate ceramics; Shear bond strength.