Effect Of Low-power Laser Irradiation On Periodontal Regeneration: An Experimental Animal Study

[Object]: To investigate the effect of low-power laser irradiation on periodontal regeneration with the hope for finding the new methods to treat periodontitis, improving the efficiency of periodontal tissues regeneration and providing the basis for developing the range of low-power laser application on the therapy of periodontal disease. [Materials and Methods]: All premolars and the first molars of three Beagle dogs were used to create Class II furcation defects model by surgically removing alveolar bone and placing metal ligaments, and randomly assigned to one control group and three treatment groups. The control group was treated by flap operation only. The treatment groups were cured by flap operation plus the low-power He-Ne laser(632. 8nm, 6mw) irradiation with energy setting of 4J/cm2, 6J/cnr\ 8J/cnf respectively on the furcation defects area and exposing root surfaces . The three dogs were randomly divided into three times for observing. The periodontal tissues of 1 month, 2 month and 3 month after treatment were evaluated through oral examination, X-way inspection, light microscope (LM) (hematoxylin and eosin , Masson trichrome), and transmission electron microscope(TEM) respectively. The new formation bone tissue within furcation was detected by scanning electron microscope (SEM). The content of calcium (Ca) and phosphorus (P) in the bone was analyzed by electron probe. [Results] : 1. The Beagle dog Class II furcation diseases model were well created. Among three dogs, the moderate to serious inflammation in the periodontium was observed. Furcation defects index II and clinical attachment level (CAL) loss were found. X-way inspection showed that alveolar bone absorbed apparently especially in furcation area. 2. In both treatment groups and control group, the CAL comparison between prior and post therapy showed no significantly different statistically. Absorption of alveolar bone detected by X-way appeared no obvious changes also. 3. The5descriptive analysis indicated that the group with irradiation of 4J/cra2 He-Ne laser showed the repair of periodontal ligament, more osteoblasts emergence, cancellous bone formation compared with the control group and other laser groups. 4. Compared to the control, furcation alveolar bone elementary analysis for all laser groups displayed the ratio of P205 and CaO (percentage of WT) which was more close to the normal alveolar bone. [Conclusion] : 1. The irradiation of 4J/cnT He-iNe laser can stimulate collagen synthesis of periodontal fibroblast, repair of periodontal ligament, formation of cancellous bone. 2. The ratio of P205/CaO in laser groups is more close to criterion than in the control. 3. There were no apparent advantage for laser treatment group comparison to the control group in the view of the oral examination and X-way inspection using set energy in this study. 4. The effect of He-Ne laser on periodontal regeneration should be studied deeply.