| Dental plaque has been shown to be the primary etiological agent for periodontal disease. The cementum of roots exposed to plaque - infected periodontal pockets undergoes several changes that decrease biocompatibility. The reattachment of gingival tissues to previously diseased root surfaces is a major goal of periodontal therapy.The classic method of treating root surfaces to achieve biocompatibility has been scaling and root planing. However, such instrumentation often precludes the achievement of the desired biologically compatible root surface totally free of surface contaminants. The option of the adjunctive use of chemical root treatments such as root demineral-ization with citric acid appears to have had minimal impact on clinical outcomes.Recently, the Nd: YAG laser has been proposed as an instrument with great potential for facilitating root planing. Nd: YAG laser has been purported to eliminate surgical pain, coagulate blood, vaporize plaque, calculus, smear layer, detoxify endotoxin, desensitize root surface. Nd: YAG laser has also the ability of sterilization, could reduce the numbers of scaling strokes for calculus removal . However, Nd; YAG laser irradiation cause surface alterations including charring and carbonization of root surface, crater formation, melting and reso-lidification of cementum et al.The purpose of this study was to evaluate the effect of Nd: YAG laser irradiation on periodontally involved root surfaces in vitro when used in combination with manual or ultrasonic instrumentation, and provide morphological evidence for discussing the possibility of using Nd:YAG laser subsidiary treating periodontal diseases.Materials and MethodsThe experimental unit consisted of 24 freshly extracted human periodontally diseased single rooted teeth. The test area on each tooth was the proximal surface. A circular area 3mm in diameter located 2 to 3mm apical of the cemento - enamel junction ( CEJ) was outlined with a water - cooled high - speed bur.Twenty - four specimens were assigned randomly to four groups; (1) manual scaling and root planing (SRP) + irradiation, (2) irradiation + manual SRP, (3) ultrasonic scaling + irradiation, (4) irradiation + ultrasonic scaling. Group ( 1) and (2) were divided into 3 subgroups, irradiated with 3 different energy levels.Scaling and root planing with manual or ultrasonic instrument terminated up of disappearance of roughness. The Nd: YAG laser irradiation with 0. 3mm contact optical fiber in parallel alignment to the root surface, continuously moved back and forth to cover the entire area 3mm in diameter.All the specimens were prepared for SEM examination.ResultsUsing SEM, all specimens scaled by ultrasonic or manual instrumentation only, observed surface smear layer, consistent of residual calculus and irregular debris.Manual SRP + irradiation: Root surfaces in specimens which had been irradiated with different energy levels appeared similar texture , most demonstrated smoother surface topography, probably artificial cracks produced by laser, cementum charring and residual carbonized calculus were visible, crater was visible occasionally.Irradiation + manual SRP: In the specimens which had been irradiated with different energy levels exhibited similar root surface topography, most showed smoother, some region exhibited cementum charring, residual carbonized calculus, cementum peeling and dentine exposure. One specimen appeared cleanly evenly granular texture.Ultrasonic scaling + irradiation; Specimens exhibited smoother surface topography, small debris often was visible. Charring and cementum melting resulting from the laser was visible too.Irradiation + ultrasonic scaling: Specimens exhibited scale -like surface topography.DiscussionThe treatment of periodontal disease has three major aspects; elimination of inflammation, prevention of recurrent disease and regeneration of lost tissues. It is necessary to alter periodontally diseased root surfaces be rendered biologically compatible.Scaling and root p...
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