Conditioning of enamel with Nd:YAG and CO2 dental laser systems and with phosphoric acid. An in-vitro comparison of the tensile bond strength and the morphology of the enamel surface.
MATERIAL AND METHOD 1: The first stage of a three-stage in-vitro investigation used 146 maxillary incisors to identify optimum setting parameters for two CO2 and Nd:YAG standard laser systems applied in enamel conditioning for bracket bonding.


RESULTS
31 of the 75 parameter combinations investigated for the Nd:YAG laser and nine of the 71 investigated for the CO2 laser proved appropriate for further investigation of tensile strength. MATERIAL AND METHOD 2: In a second stage, tensile bond strength for the selected laser settings was determined in comparison to the conventional acid-etch technique for a further 210 teeth as the control group.


RESULTS
The highest average tensile strength for the Nd:YAG laser was 4.1 MPa, with comparable values of 3.3 MPa for the CO2 Laser and 4.9 MPa for the acid-etch technique. MATERIAL AND METHOD 3: The third stage of the investigation involved comparative scanning electron microscopy of enamel surface morphology following laser application and acid-etching.


RESULTS
The CO2 laser was found to produce craters of various dimensions, while the Nd:YAG laser produced honeycomb structures regionally similar to enamel samples from the acid-etch technique.


CONCLUSIONS
The CO2 and Nd:YAG dental lasers tested produce enamel conditioning and tensile bond strength sufficient to meet the requirements of bracket bonding.
Fuhrmann
R
R
Department of Orthodontics, University of Aachen, Germany. robertfuhrmann@web.de
Gutknecht
N
N
Magunski
A
A
Lampert
F
F
Diedrich
P
P
D000134:Acid Etching, Dental; D001840:Dental Bonding; D003743:Dental Enamel / Q000033:anatomy & histology; D006801:Humans; D007834:Lasers; D008855:Microscopy, Electron, Scanning; D016910:Orthodontic Brackets; D010756:Phosphoric Acids; D013499:Surface Properties; D013718:Tensile Strength; D014016:Tissue Conditioning, Dental
D010756:Phosphoric Acids; C030242:phosphoric acid