A Rare Case Of Severe Periodontitis Complicated With Multiple External Root Resorption And Its Etiological Analysis

BackgroundMultiple external root resorption(Multiple external root resorption,MERR)is a rare disease characterized by rapid resorption of three or more teeth,which further leads to tooth loss.Severe periodontitis,especially rapidly progressive periodontitis,is also an important cause of alveolar bone resorption and tooth loss.The etiology of MERR is various.The suspected risk factors include severe periodontitis,occlusal trauma,and systemic immune disorders,etc.MERR is not excluded as a multi-factor disease.However,due to the limited reported cases,it is still difficult to clarify the etiology of MERR,and the treatment and intervention methods still need to be improved.At present,reports of severe periodontitis combined with MERR are more rare.ObjectiveThis study intends to report a rare case of severe periodontitis combined with MERR.Through complete clinical examination,diagnostic treatment,histological and genetic analysis,and animal experiments,it is expected to identify the risk factors associated with periodontitis and MERR,and to provide reference for the treatment of this rare disease.Material and MethodsIn the first part,a 43-year-old male patient with the chief complaint of "gingiva swelling and pain accompanied by tooth loosening for 4 years and aggravated for 2years",and the preliminary diagnosis was "multiple periodontal abscess of lower anterior teeth,severe chronic periodontitis and MERR of teeth 33-43".The patient was subjected to periodontal systemic therapy and close monitoring of MERR,followed up for three years,and screened out the risk factors that may be associated with periodontitis and MERR.The second part was histological and genetic experiments.MERR teeth were collected and the histological characteristics of MERR were analyzed by pathological sections.Venous blood of patients was collected,and 11 related gene polymorphism sites,including IL-1A、IL-1B、IL-1RN、IL-6、P2RX7、P2RX7-2、TNFRSF11B(OPG)、SPP1、SPP1-2、IRAK1、Taq I and a hereditary disease gene IFIH1,were detected by gene polymorphism sites,so as to screen the susceptible genotype of MERR.In the third part,the relationship between hyperuricemia(hyperuricemia,Hu)and periodontitis was explored with Hu as the starting point.A compound animal model of Hu and periodontitis was established by randomly dividing 14 KM mice into Hu group and control group.Bone volume fraction and bone mineral density were analyzed.Serum uric acid concentration was detected and the effect of Hu on the destruction of alveolar bone was analyzed.ResultsIn the first part,through standard periodontal system treatment and close monitoring of MERR,the periodontitis was well controlled,and the development of MERR showed the characteristics of reverse change with the effectiveness of periodontal treatment.Combined with clinical examination and diagnostic analysis,the possible risk factor associated with MERR was identified as periodontitis.In addition,since MERR affects the disease by multiple factors,systemic factors and genetic susceptibility are not excluded in this case.In the second part,gross morphology confirmed MERR of teeth 33-43.The periodontitis of teeth 33 and 41-43 developed to the apical apex were irregularly absorbed and blackened,while the periodontitis of teeth 31 and 32 did not develop to the apical apex were absorbed but clean.A large amount of inflammatory cell infiltration and a small amount of osteoclast destruction formed the absorption were identified through histopathological analysis.The absorption of teeth 31 and 32 were more regular than those of teeth 33,41-43.Through the analysis of gene polymorphism,it was found that there were three susceptible genotypes of IL-1B、IL-1RN and IL-6 in this case,whose gene sites were rs1143634,rs419598 and rs1800796,respectively.Compared this case with genetic disorders SingletonMerten syndrome using Online Mendelian Inheritance in Man,there were some similar symptoms,such as vascular anomalies(aortic insufficiency),abnormal bones(osteoporosis),a mild facial deformity of high hairline,early onset of severe periodontitis and root absorption,but there was no mutation in gene IFIH1,then eliminate the hereditary disease.Based on this part of the evidence,the main risk factors for MERR were severe periodontitis and genetic susceptibility,among which the risk of promoting MERR from genetic susceptibility may be mediated by periodontitis.In the third part,the establishment of the compound animal model of Hu and periodontitis was verified by analyzing the bone volume fraction and bone mineral density of the jaws and detecting the serum uric acid concentration.There was no significant difference in alveolar bone resorption between Hu group and control group,and there was no direct correlation between uric acid level and alveolar bone resorption.ConclusionIn this study,we reported a rare case of severe periodontitis combined with MERR,and conducted a comprehensive examination,systematic treatment and longterm follow-up.Disease progression,treatment response,histological and genetic analysis all support periodontitis as the most direct risk factor for MERR,and the patient’s genetic susceptibility to MERR may be mediated by periodontitis.Other risk factors for MERR include occlusal trauma and systemic metabolic disorders.The susceptibility factors associated with periodontitis may include systemic metabolic disorders,occlusal trauma and plaque accumulation,etc.Zoological studies do not support the idea that hyperuricemia is a predisposing factor for periodontitis.