The Orthodontic And Orthognathic Treatment For A Patient Diagnosed With Osteogenesis Imperfecta With Class Ⅲ Malocclusion:a Case Report

Osteogenesis Imperfecta(OI)is a group of genetic bone diseases with phenotypic heterogeneity caused by single gene mutations.Its main pathogenic genes,COL1A1 and COL1A2,lead to the occurrence of the diseases through their changing the quantity and structure of type Ⅰ collagen.OI is characterized by low bone mass,increase of bone fragility,repeated fractures,and bone deformities,meanwhile it also involves the systemic connective tissue system,associated with blue sclera,hearing loss and Dentinogenesis Imperfect(DGI).Of the manifestations,DGI is the most common oral feature.According to the Shields classification,the type of DGI with OI is DGI-Ⅰ.The affected teeth usually show color change,presented with gray-white or yellow-brown,and manifest to be not abrasion resistant due to the change of dentin structure.Heavier abrasion of the tooth crown and low vertical occlusal distance can be seen in a patient oral cavity.The incidence of Class Ⅲ malocclusion in OI patients is higher than that in the population without OI.The maxillary retraction and mandibular protrusion make depression on the middle part of a patient face,anterior crossbite or even posterior crossbite in the oral cavity,severe damage of masticatory function.These oral symptoms bring a disadvantage effect on the growth,development and psychological health of the patients,and prompt OI patients and their parents to come to an orthodontic department and to seek treatment.Therefore,to raise orthodontists’ awareness on OI benefits to make clear diagnosis and to realize accurate treatment.This paper reports a case of osteogenesis imperfecta with Class Ⅲ malocclusion.According to the findings of clinical and radiographic examinations,the patient was initially diagnosed with DGI.The results of molecular genetic examination showed that the mutation gene of the patient was COL1A2,the mutant site was exon31c.1801G>A,and the mutant type was p.Gly601Ser.Finally,the patient was diagnosed with OI with Class Ⅲ malocclusion.Combining multiple disciplines,we formulated a systematic protocol of treatment for the patient,designed the orthodontic and orthognathic treatment plan,and chose a clear aligner to complete the orthodontic therapy.The lateral cephalometric radiographs were measured and compared before and after treatment.Results showed that the angle SNA,SNB and ANB were returned to normal.The results of the treatment indicate that the patients’ facial shape and masticatory function are improved obviously,the quality of life of the patient is enhanced,and meanwhile,prove that the clear aligner can be used in orthodontic and orthognathic treatment,and provide a new selection of orthodontic appliances for OI patients.In addition,this paper explores the methodology for treating oral disease of OI patients through discussing the mechanism of molecular genetics and the oral clinical manifestations of OI,which provides experience and reference for the diagnosis and systemic treatment of OI oral diseases.