Bone mineral density and biomechanics test after distraction osteogenesis using TiNi-shape memory alloy distractor / 中国组织工程研究

ABSTRACT

BACKGROUND:TiNi shape memory alloy(TiNi-SMA)distractor can be buried completely,there is no time delay and it is different from other distractors previously used.Therefore,it is necessary to reevaluate the osteogenetic time and quality.OBJECTIVE:To investigate the quality of the alveolar ridge augmented by TiNi-SMA distractor by bone mineral density (BMD)and biodynamics tests of new-formed bone.DESIGN:Randomized controlled observation.SETTING:Department of Stomatology of General Hospital of Chinese PLA.MATERIALSTwelve healthy adult male mongrel canines(ranged from 21 to 26 kg)were provided and bred by Medical Experimental Animal Center of General Hospital of Chinese PLA.All the animals were accorded with the requirements of the quarantine and animal ethnics.Self-made distractors were used in the study.XR-36 Dual Energy X-Ray Absorptiometry (Norland,USA)and 858 Mini Bionix Ⅱ Biomaterial Testing Machine(MTS,USA)were used in the study.METHODS:The experiments were performed at the Medical Experimental Animal Center of General Hospital of Chinese PLA from July 2000 to May 2004.The animals were grouped into group Ⅰ(3 months group)and group Ⅱ(6 months group)randomlv with 6 animals in each group.The left mandible was used as experimental side and the right was used as COntrol side.The canines were kilied after anaesthesia at 3 or 6 months later in both groups.After the mandible samples were cut,the BMD of three points in the distraction gap,above the distraction gap and below the distraction gap were measured by dual energy X-ray.Compressive biomechanics test was performed in the middle of the distraction area of the experimental side and the corresponding area of the control side to detect compressive stress and the modulus of elasticity.MAIN OUTCOME MEASURES:①BMD of the distraction area of the experimental side and the control side in the group Ⅰand group Ⅱ.②Compressive strength and modulus of elasticity of the mandibles of the experimental side and the control side.RESULTS:All of the 12 experimental canines were included in the final analysis,no drop-out.BMD determinationBMD was lower in above the distraction gap of the mandibles of the experimental side than in the control side in the group Ⅰ (t=-2.898,P＜0.05).There was no significant difference in BMD between both sides in the group Ⅱ(P＞0.05).Compressive biomechanics testCompressive stress and the modulus of elasticity of the mandibles on the experimental side were lower than on the control side in the group Ⅰ(t=-3.274,-3.534,P＜0.05).All indexes increased by some degree in the group Ⅱ compared to the group Ⅰ (P＞0.05).CONCLUSION:The new bone is strong enough for later repair such as implantation after distraction osteogenesis using TiNi-SMA distractor.