title: Effects of Nd:YAG laser radiation on removal of a root surface smear layer after root planing: a scanning electron microscopic study.
abstract: A scanning electron microscopy (SEM) study was conducted to evaluate the effects of Nd:YAG laser radiation on removal of a root surface smear layer after root planing in comparison with citric acid treatment. The experimental materials were 15 human teeth affected by severe periodontal disease, which were extracted because of a hopeless prognosis. The teeth had at least 5 mm of attachment loss on the proximal surface tested. After removing all visible calculus using an ultrasonic scaler, each proximal surface was vigorously scaled and root planed with a Gracey curet. Thirty specimens were cut from the root-planed proximal surfaces and assigned randomly to one of two groups: Group A (25 specimens) was divided into 5 subgroups and irradiated with a Nd:YAG laser, using non-contact delivery (3 mm beam diameter, distance from the tip to the specimen 5 cm), at a measured power of 20 W for 0.3, 0.5, 1.0, 2.0, or 3.0 seconds corresponding to energy densities of 84.93, 141.54, 283.09, 566.17, or 849.26 J/cm2; Group B (5 specimens) was not irradiated, but treated for 3 minutes with saturated citric acid (pH 1). The center of each specimen in Group A was used as the experimental area (Exp A) treated by laser irradiation and the peripheral area of the specimen served as a control (Cont A). In Group B, one half of the specimen was used as the experimental area (Exp B) treated by citric acid and the other half served as a control (Cont B). The specimens were then fixed and examined by SEM. The surface of the root-planed specimens (Cont A and B) was irregular, corresponding to the presence of a smear layer, and had an amorphous appearance. Both root surfaces of Exp A and B exhibited clear orifices of dentinal tubules and intertubular dentin without a smear layer. Although the root surface of Exp A showed clear orifices of dentinal tubules with a flat morphology, the root surface of Exp B showed widened funnel-shaped dentinal tubule orifices with a fibrillar, mat-like morphology. The present results indicate that Nd:YAG radiation effectively removes the smear layer, uncovers dentinal tubules, and exposes collagen fibers on the root surface without widening the orifices of dentinal tubules after root planing.
authors.affiliation: Department of Periodontology, Nihon University School of Dentistry, Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ito
authors.forename: J
authors.initials: J
authors.lastname: Nishikata
authors.forename: S
authors.initials: S
authors.lastname: Murai
mesh_terms: D000538:Aluminum Silicates; D002951:Citrates / Q000494:pharmacology; D019343:Citric Acid; D003094:Collagen / Q000187:drug effects / Q000528:radiation effects; D003739:Dental Cementum / Q000187:drug effects / Q000528:radiation effects / Q000648:ultrastructure; D003804:Dentin / Q000187:drug effects / Q000528:radiation effects / Q000648:ultrastructure; D006801:Humans; D053685:Laser Therapy; D008855:Microscopy, Electron, Scanning; D009354:Neodymium; D011829:Radiation Dosage; D016745:Root Planing; D016369:Smear Layer; D014092:Tooth Root / Q000187:drug effects / Q000528:radiation effects* / Q000648:ultrastructure; D015019:Yttrium
chemical_list: D000538:Aluminum Silicates; D002951:Citrates; D019343:Citric Acid; D009354:Neodymium; D015019:Yttrium; D003094:Collagen