الفهرس 
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Abstract
To evaluate the shear bond strength of metal and ceramic brackets bonded to different CAD/CAM ceramic materials etched with hydrofluoric acid vs. phosphoric acid. Materials and methods : One hundred and twenty CAD/CAM ceramic blocks in 12 groups were fabricated from 3 different CAD/CAM ceramic materials; VITABLOCS Mark II (VM), VITAENAMIC (VE) and IPS e.max CAD (EM). Each ceramic material group was divided into two etching groups; one treated with 9.5% hydrofluoric acid (HFA) and the other treated with 37% phosphoric acid (PA). Sixty metal and ceramic orthodontic brackets of upper right central incisor were bonded to the HFA treated blocks. Another 60 metal and ceramic brackets were bonded to the PA treated blocks. They were bonded using Transbond XT light cure adhesive. All bonded specimens were thermocycled prior to shear bond strength (SBS) testing. Then the mode of bond failure was recorded with the aid of stereomicroscope. Data were collected and analyzed using One-way ANOVA, Kruskal-Wallis H, Chi-Square, t, Mann-Whitney U test, Pairwise comparisons and three-way ANOVA. Results : There was no statistically significant difference in SBS values between the three CAD/CAM ceramic materials. The HFA treated specimens presented a statistically significant higher SBS values than the PA treated specimens. Also, the SBS values of ceramic brackets were significantly higher than those of metal brackets. The adhesive remnant index (ARI) scores were 4 for most of the groups; meaning that almost no adhesive remained on the porcelain surface. There was a statistically significant difference in the proportions of ARI scores between the study groups.Conclusion : There was no main influence of CAD/CAM ceramic material type on SBS values. However, there was a statistically significant main effect of both the etching method and the bracket type on SBS values.