An Ex-vivo Shear and tensile bond strengths of orthodontic molar tubes bonded using different techniques

Background: Molar bonding procedures need continuous improvement to be widely accepted clinically and eventually
replace molar bands.
Material and Methods: The purpose of this study was to determine the effects of enamel micro-abrasion and silane
coating of the base of molar tubes on shear and tensile bond strengths of orthodontic molar tubes. A total of 200
third molars were randomly allocated into five groups of 40 teeth as follows: group 1: molar tubes bonded to etched
teeth (37% phosphoric acid gel; control group); group 2: molar tubes bonded to etched teeth (37% phosphoric acid)
with the addition of silane to the base of molar tubes; group 3: molar tubes bonded to teeth pre-treated with 18%
hydrochloric acid and pumice (micro-abrasion); group 4: molar tubes bonded to teeth pre-treated with microabrasion
with the addition of silane to the base of molar tubes; group 5: molar tubes bonded to teeth pre-treated with
microabrasion before conventional acid etching combined with the addition of silane to the base of molar tubes.
The bond strength testing was performed using a computer control electromechanical universal testing machine.
Results: The highest mean shear and tensile bond strengths were recorded in group 5 (13.81±2.54MPa and
13.97±2.29 MPa, respectively). Micro-abrasion alone (group 3) and the combination of enamel micro-abrasion and
the addition of silane (group 4) produced bond strength values comparable to the control.
Conclusions: Enamel surface pre-treatment (micro abrasion) before conventional acid etching combined with the
addition of silane to the base of the molar tube produced the highest bond strengths among all tested groups.