| ObjectiveTo establish hypothyroidism (low bone metabolism) animal model to study the case of low bone metabolism , the feasibility and stability of immediate load micro-implant anchorage for the clinical application of theoretical guidance and experimental basis.MethodsVistar 20 female rats were randomly divided into two groups, n = 10, A group of hypothyroidism (low bone metabolism in group), B group (control group of normal bone metabolism in group). Hypothyroidism (low bone metabolism in group) to give 0.1% propylthiouracil; control group was given distilled water, 2 groups according to 10μL / g body weight per day orally. After 28 d collect angular vein plexus blood 3ml, detect serum T3, T4, TSH, serum osteocalcin (BGP), alkaline phosphatase (ALP), calcium (Ca), phosphorus (P), leaving 24 hour urine calcium / urine creatinine (Ca / Cr) test. Implant micro-implant and immediately loading 0. 98N After established animal model , respectively 16,17,26,27 day after afterburner tag animals ,then sacrificed 30 d after the afterburner. Acquisition rat mandible and bilateral tibia, mandible, and the right tibia bone for mineral density test and correlation analysis; the left tibia with implants made of bone tissue grinding; fluorescence microscope,laser scanning confocal microscope,light microscope with ultra-growing nail Hard tissue sections and calculate the bone mineral apposition rate, bone contact ratio. Results1.General: the symptoms of hypothyroidism group consistent with the clinical features of hypothyroidism. Throughout the experiment, 2 group rats with micro-implant anchorage kept good stability, micro implants without loosening off.2.Establish model: after 28days, the weight gain and heart rate of hypothyroidism was slower than the control group; blood T3, T4 levels were significantly lower than the control group, TSH levels were significantly increased compared with normal control group, the difference was statistically significance. (P <0.01). The serum alkaline phosphatase (ALP)and serum osteocalcin (BGP) of hypothyroidism was lower than the control group, the difference was statistically significant (P <0.05, P <0.01); urinary calcium / creatinine ( Ca / Cr):hypothyroidism group was higher than the control group, the difference was statistically significant (P <0.05); the serum calcium with reflect the bone mineralization of hypothyroid group than the control group; phosphorus contrast, a higher hypothyroidism group, but no significant difference between the two groups (P> 0.05). These results suggest that: hypothyroid rats in hypothyroidism, low bone turnover state. The animal model was successful.3.Bone mineral density: mandibular and tibial bone mineral density of hypothyroid group, were lower than the control group (P <0.01). Through correlation analysis of rat mandibular and tibial bone mineral density values shows that rat mandibular and tibial bone mineral density was highly positively correlated.4.Micro-Implant Distance Comparison: 2 group implant occurred displacemen during loading, hypothyroidism group displacement speed slowly was significantly less than the control group, the difference was statistically significant (P <0.05) .5.Bone mineral deposition comparison: the results of double labeling fluorescence microscopy, fluorescence can be seen mainly in trabecular bone surface and the implant - bone interface, the control group, a strong fluorescent labeling, marking with a wide pitch, hypothyroidism was weak mark , marked with a distance significantly narrower than the control group. The bone mineral deposition rate of hypothyroidism was slower than the control group, the difference was statistically significant (P <0.01). Laser confocal microscope (LSCM) verified the observation under the fluorescence microscope further.6.Osseointegration compared to the situation: the control group were observed around the implants can be seen that trabecular bone of cancellous bone area was concentrate and uneven thickness; The cortical bone around the implant in hypothyroidism group was slightly thinner, cancellous bone area of trabecular bone thinning and thinner, amputation partly. The micro-implant anchorage of hypothyroidism and the control group, immediately loading 0.98N month later, have shown good biocompatibility, micro-implant - bone interface showed varying degrees of Synostosis. The synostosis rate of hypothyroidism was lower than the normal group, the difference was statistically significant (P <0.01).Conclusion1. Rats with 0.1% propylthiouracil (PTU) at 10μL / g body weight per day orally, 28d later,low bone metabolism in rats can be establishmented.2.Low bone metabolism has influence to the stability of micro-implant, However, hypothyroidism with normal micro-implant group was no fall off, the remodeling of bone around implant was basically normal, implant - bone interface showed varying degrees of bone, indicating that the case of low bone metabolism in micro-implants for immediate loading was feasible.3.Micro-implant anchorage was not absolute, was a very good anchorage device to strengthening. |
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