Debonding of ceramic brackets by a new scanning laser method.
BACKGROUND
The purpose of this in-vitro study was to develop a new method to debond ceramic brackets by scanning with an Er:YAG laser.


METHODS
Sixty bovine mandibular incisors were randomly divided into 2 groups of 30. Polycrystalline ceramic brackets were placed on their labial surfaces by using the orthodontic composite adhesive Transbond XT (3M Unitek, Monrovia, Calif) and light cured for a total of 40 seconds. The first group was the control group, with no laser application performed. The Er:YAG laser was used on each bracket in the study group at 4.2 W for 9 seconds with the scanning method. The force required for debonding the brackets was applied 45 seconds after laser exposure. Shear bond strengths were measured in megapascals with a universal testing machine, and adhesive remnant index scores were assigned to each specimen.


RESULTS
Statistically significant (P <0.001) lower shear bond strengths were found in the laser group (9.52 MPa) compared with the control group (20.75 MPa). Likewise, the adhesive remnant index scores were statistically different (P <0.001); the laser group had twice as many samples with adhesive, with the adhesive remnant index scores of 2 or 3.


CONCLUSIONS
The application of the Er:YAG laser with the scanning method is effective for debonding ceramic brackets by degrading the adhesive through thermal softening.
Oztoprak
Mehmet Oguz
MO
Department of Orthodontics, Faculty of Dentistry, Yeditepe University, Istanbul, Turkey.
Nalbantgil
Didem
D
Erdem
Ayşe Sine
AS
Tozlu
Murat
M
Arun
Tülin
T
D000818:Animals; D002417:Cattle; D003738:Dental Cements / Q000528:radiation effects*; D017005:Dental Debonding / Q000295:instrumentation* / Q000379:methods; D003743:Dental Enamel / Q000528:radiation effects*; D003776:Dental Porcelain; D053844:Lasers, Solid-State; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D011897:Random Allocation; D019279:Resin Cements / Q000528:radiation effects*; D033081:Shear Strength
D003738:Dental Cements; D019279:Resin Cements; C477790:Transbond XT; D003776:Dental Porcelain