Experimental Study Of RhPTH1-34 On The Prevention And Treatment Of Osteoradionecrosis Of The Jaw In SD Rats

Objectives: To investigate the effect of rhPTH1-34 on the prevention and treatment of osteoradionecrosis of the jaw in SD rats,and to provide evidence for the clinical use of rhPTH1-34 in the prevention and treatment of ORNJ.Method: Sixteen 6-week-old male SD rats were randomly divided into four groups(n=4).Group Ⅰ:Tooth extraction group;Group Ⅱ:Radiotherapy and tooth extraction group;Group Ⅲ:Prophylaxis group;Group Ⅳ:Treatment group.Group Ⅲ was intraperitoneally injected with rhPTH1-34 at 30μg/kg/ day for 21 days.The right mandible of rats in groups Ⅱ,Ⅲ,Ⅳ were irradiated with 4Me V electron line for 5 days,each time with 7Gy.After the irradiated,the right mandibular third molar of the rats in the 4 groups was extracted through the oral approach.Three weeks after the extraction with radiation therapy,Group Ⅳ was given 30μg/kg/ day rhPTH1-34 intraperitoneal injection for 21 days.Body weight and clinical symptoms of the rats were recorded regularly.6 weeks after tooth extraction,Micro-CT was taken of the right mandible of the rats and bone microdata were analyzed.HE and Masson staining were performed to observe the bone changes in the mandible.Results: The experimental animals showed mild listlessness,weight loss,and mild appetite loss in the first few days after radiotherapy.At 42 days after tooth extraction,the weight difference among the four groups was statistically significant(P<0.05).The tooth extraction wounds in groups Ⅲ and Ⅳ had different degrees of healing.Bone microscopic data analysis of groups Ⅲ and Ⅳ showed higher BMD,BV,BV/TV and BS/TV values than those of group Ⅱ,and the difference was statistically significant(P<0.05).HE and Masson staining showed that compared with group Ⅰ,a large number of inflammatory cells infiltrated in the tooth extraction wound,tissue fibrosis increased and tissue liquefaction necrosis was observed in group Ⅱ.The bone structure of group Ⅲ was basically normal with a small amount of vasodilation and mild fibrosis.In group Ⅳ,a small number of inflammatory cells were infiltrated and bone trabecular density decreased.Conclusions: Teriparatide has a certain preventive and therapeutic effect on osteoradionecrosis of the jaw in rats,which can provide a new idea for the clinical treatment of osteoradionecrosis of the jaw.