Dental implants were used for reconstruction of oromaxillofacial defects and they were widely used in dental and medical fields. The implant materials are various , including titanium and ceramics such as zirconium. The property of implant materials have biocompatibility and mechanical strength. Titanium has direct bone anchorage without any other tissues between implant's interface. many researcher's had studied for raising the osseointegration success rate through various method. It was reported over 95% success ratio. many researcher's study the enhancing the speed of bone remodelling and osseointegration. Low Level Laser Therapy is one of the method to accelerlate the speed of bone remodelling and osseointegration. Thus it raise initial stability. The purpose of this study was to evaluate the effect of diode laser irradiation for ossoeintegration in implant interface and between the implants threads. 24 New Zealand white rabbits which were about 3Kg, used for experiment. 2 implant's were implanted every rabbit's tibia. 2 weeks, 4 weeks, 8 weeks after implantation, tissue sample were removed from sacrificed rabbit's tibia. 8 rabbit's were sacrificed every 2, 4, 8 weeks and undecalcified sample were got from tissue sample. The undecalcified samples were investigated by optical microscope. 2 weeks, 4 weeks, 8 weeks experimental groups which were irradiated low level laser therapy showed rapid bone remodelling than control groups. it showed many difference especially in initial stage. Low level laser irradiation increase the volume of new bone formation in implant interface . It was suggested that there were many influence in bone remodelling in early stage, because these were many differences between experimental and control groups. Low level laser irradiation were helpful for immediate loading implant

Currently, Low-level laser therapy (LLLT) is widely used in medicine and dentistry. It has been suggested that LLLT may be beneficial in management of many different medical conditions, including pain, wound healing and nerve injury. Stimulation with LLLT can enhance bone repair as reported in experimental studies on bone defects and fracture healing also. As far as hard tissue is concerned, the biostimulating effect of laser has been demonstrated more rapid healing of tibial bone fracture in mice. This study was performed to compare new bone formation between with LLLT and without LLLT. Two cylinder implants(5mm diameter, 5mm length) were implanted on rabbit's tibia. LLLT was done to one implant with 632mm diode laser. And than Rabbit's were sacrificed after 2nd, 4th, 6th, 8th weeks after implantation. Bone with implant were removed and fixed with 10% formaline. Undecalfied sample were prepared after spurr low resin embedding. Sample were grind and polished to 100㎛. The results were as follows. The amount of trabeclue of experimental group were superior to that of control group from 2 weeks to 8 weeks. There were no difference in arrangement of trabecule between two groups. Bone implant contact were significantly increased at 4th weeks in experimental group. The number of ostecytes in trabecule were different at 4th weeks experimental group. Osteone were appeared dominantly at 6th weeks experimental group, while at 8th weeks experimental group were superior than control group. LLLT group showed increased amount of trabecule, bone implant contact, number of osteocytes & osteone. It suggested that LLLT might be increase the bone formation rate and accelerate the bone formation time.

Hydroxyapatite(HA) has been widely used as bone substitutes to rehabilitate bone loss area by new bone formation. But there were some problem of bone formation around HAs due to a little space between HAs embedded in bone loss area. The purpose of this study was to observe morphologically new bone formation around HAs mixed with PLGA block (5.5㎜ in diameter, 4 mm in depth) in Newzealand white rabbit tibia. Before 1 week of sacrification, Alizarin red was injected intraperitoneally into rabbit. At 3 day, 1, 2, 4, 10, 18, 32 weeks, bones with HA as control group(CG)and HA mixed with PLGA block as experimental group (EG)were fixed with 10 % neutral formalin, dehydrated, and embedded with Spurr low viscosity resin. After the specimens were cut by 500 ㎛ with slow diamond wheel saw, these were coated with carbon and examined by REM, LSM and qualifative analysis of calcium and phosphorous deposition were done with EPMA. The obtained results were as follows. 1. Both group showed scattered HA around compact bone under REM and little AZ labelled bone under LSM at 3 days. 2. Both group showed active AZ labelled bone, while EG showed higher Ca(calcium) and P(phosphate) deposition than that of CG at 1 wk. 3. There was decreased AZ labelled bone of both group under LSM. REM of EG showed HA associated with new bone from compact bone, while EPMA features showed similar to Ca and P deposition at 1 wk and EG showed higher than that of CG. 4. REM features of both group showed resorbed HA associated with new bone. There was decreased AZ labelled bone of both group under LSM. EPMA features showed higher Ca and P deposition at 4 wks than that of 2 wks. 5. New bone of both group was well demarcated from compact bone under REM at 10 wks. LSM features showed various AZ labelled bone, but weak AZ labelled than that of CG. 6. LSM features of 14 wks showed discontinuous AZ labelled on osteon formation. EPMA of both group showed increased Ca deposition, while there was higher Ca deposition of EG and similar P deposition to CG. 7. REM featureless of 18 wks in EG showed similar gray color to compact bone. LSM features showed osteon formation with little concentric lamellars. EPMA of both group showed increased Ca deposition, while there was higher Ca and P deposition of EG. 8. New bone was ill demarcated from compact bone and increased otseon formation of REM features at 32 wks. There was little AZ labelled bone. EPMA features showed higher Ca and P deposition of EG than that of compact bone. From the aboving results, there was early active AZ labelled bone of both group within 1-2 weeks and since 18 weeks new bone with active osteon formation was poorly demarcated from compact bone. Calcium deposition of EG was early increased than that of CG deposition since 4 weeks after experiments. It was suggested that EG showed active and rapid new bone formation and similar bone mineralization of compact bone