[Scanning  electron microscopy was used to observe dentin morphology in primary and permanent teeth treated by erbium:  yttrium-aluminum-garnet laser].
OBJECTIVE
To observe the morphological change of cavities in teeth prepared using the erbium: yttrium-aluminum-garnet (Er:YAG) laser with different  parameters.


METHODS
Ten extracted cavity-free molars were divided into control group and experiment group. The control group included 2  permanent teeth and 2 primary teeth. The experiment group was divided into 3 groups according to the different laser parameters. Group 1 included 2  permanent teeth, while group 2 and group 3 included 2 primary teeth respectively. Cavities were prepared using traditional handpieces in the control group  or the Er: YAG laser with different parameters in the experiment group (group 1: Er:YAG laser 20 Hz/200 mJ,group 2: Er:YAG laser 10 Hz/300 mJ,group 3: Er:YAG laser 10 Hz/400 mJ) .The samples were made for Scanning Electron Microscopy(SEM) analysis.


RESULTS
The dentin surface of cavities using  Er:YAG laser showed no formation of smear layer and open dentinal tubules. Dentin melting was not detected after preparation of groups 1 and 2. There  were cracks and micro-fissures in the dentin surface of the primary teeth prepared using Er:YAG laser 10 Hz/400 mJ.


CONCLUSIONS
Appropriate Er:YAG  laser parameters(groups1 and 2) were effective and safe for ablation of hard tissue of primary and permanent teeth. The high power Er: YAG laser 10  Hz/400 mJ would damage the dentin surface when used in primary teeth.
Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology, Beijing 100081, China.
Sun
S
Zhang
Tao
T
Chen
Li-hong
LH
Ge
D002648:Child; D003737:Dental Cavity Preparation / Q000295:instrumentation / Q000379:methods*; D003804:Dentin / Q000648:ultrastructure*; D006801:Humans; D053844:Lasers, Solid-State; D008855:Microscopy, Electron, Scanning; D008963:Molar / Q000648:ultrastructure; D013499:Surface Properties / Q000528:radiation effects; D014094:Tooth, Deciduous / Q000648:ultrastructure