Influence of Er:YAG laser surface treatment and primer application methods on microtensile bond strength self-etching systems.
OBJECTIVE
The aim of this in vitro study was to evaluate how surface preparation and primer application technique can influence the microtensile bond strength of self-etching system.


BACKGROUND
One of the possible applications of dental lasers includes increasing the quality of bond strength.


METHODS
12 extracted, sound human molars were ground flat to expose occlusal dentin and were then divided into six groups (G1-G6)(n = 30-36) according to surface preparation and primer application (active or passive): G1-diamond bur (DB) + active primer (AP); G2-DB + passive primer (PP); G3-Er:YAG laser (EL) + AP; G4-EL + PP; G5-#600-grit paper disc (PD) + AP; G6-PD + PP. After adhesive procedure, 5-mm high composite buildups were created with Z 250. After storage in water at 37 degrees C for 24 h, teeth were vertically sectioned into serial 1- mm2 sticks. Samples were tested for tension in an Instron machine at 0.5 mm/min. Nine additional molars were prepared to morphological analysis. Regular grit diamond bur, Er:YAG laser, or #600-grit SiC paper was used for SEM observations of dentin surfaces of each group before and after treatment with self-etching primers. Microtensile data were submitted to statistical analysis.


RESULTS
G1-43.85 +/- 9.60 MPa; G2-24.28 +/- 8.90 MPa; G3-24.11 +/- 4.05 MPa; G4-23.30 +/- 4.21 MPa; G5-55.64 +/- 8.50 MPa; G6-56.45 +/- 12.05 MPa.


CONCLUSIONS
(1) Er:YAG laser and diamond burs are able to create distinct smear layers; however the resistance of dentin/adhesive interface is similar. In this way, we can use both instruments clinically without diminishing bond strength; (2) the #600-grit sandpaper disc least affects resistance and is highly recommended for in vitro studies to achieve standard preparation of dentinal surface; (3) active primer application is the method most recommended, despite the type of dentin preparation instrument used.
Manhães
Lussaraazevedo
L
Campos School of Dentistry, Operative Dentistry Department, Rio de Janeiro, Brazil.
Oliveira
Denise Cerqueira
DC
Marques
Márcia Martins
MM
Matos
Adriana Bona
AB
D045662:Dental Etching; D006801:Humans; D007834:Lasers; D008855:Microscopy, Electron, Scanning