Study On The Correlation Between Different Types Of Ponticulus Posticus And Craniomaxillofacial Tissues

Background and objective:Ponticulus posticus is a bony variation of atlas.It consists of a fully or partially calcified bone structure over the groove for vertebral artery of atlas.The ponticulus means"small bone bridge"in Latin.Various terms have been used to describe ponticus posticus in the literature,including arcuate foramen,Kimmerle deformity,sagittal foramen,posterior atlas foramen,posterior articular vertebral artery canal,and vertebral canal.The variation can cause many neurological symptoms,including balance problems,blurred vision,migraines,tinnitus,dizziness,etc.The complete ponticulus posticus is 5 to 11 times more likely to cause neurological symptoms than the incomplete ponticulus posticus,and will give neurosurgeons the false impression of widening of posterior arch of atlas,which can lead to vertebral artery injury during surgical treatment of atlantoaxial instability.Ponticulus posticus can be detected by stomatologist and maxillofacial radiologists in X-ray lateral cephalometric radiograph,and can be more accurately diagnosed in conventional computed tomography(CT)or cone-beam computed tomography(CBCT).The evaluation of the lateral cephalometric radiograph is one of the important steps in developing an orthodontic treatment plan.Because the lateral radiograph has a low radiation dose,it is an ideal screening radiographic tool for detecting this abnormality.At present,in clinical orthodontic treatment,doctors are not only paying attention to tooth occlusion and Craniomaxillofacial growth and development,but also paying more and more attention to the shape of the cervical spine and head-neck posture.Because the cervical spine and the skull base have the same embryonic origin,the occurrence and development of the jaw bone is related to the skull base,so there is a certain connection between cervical vertebra deformity and skeletal malocclusion.Studies at home and abroad have shown that cervical spine morphology is correlated with a variety of skeletal malocclusions.According to reports by Liu Yi and Yang Xiaofeng,the more deep the malocclusion of the patient,the higher the incidence of cervical fusion,and the higher the incidence of more than 2 cervical vertebra abnormalities.A study by Sonnesen et.al.pointed out that 42.1%of patients in the open jaw group had cervical spine fusion,13.2%of patients had posterior arch defects,and cervical fusion usually occurred in C2 and C3.Compared with the control group,the incidence of cervical spine abnormalities in the open jaw group significantly increased.Precious studies have show that ponticulus posticus has correlations with tooth malocclusion,styloid process,cleft lip and cleft palate.Adisen and Misirlioglu systematically studied the relationship between cervical spine morphology and mandibular position,and tried to determine the prevalence of ponticulus posticus in different malocclusion groups.However,there was no statistically significant difference in the prevalence of ponticulus posticus between the malocclusion groups.Bayrakdar and other scholars evaluated the CBCT images of 181 patients with different sagittal skeletal features.Ponticulus posticus had the highest detection rate in patients with skeletal Ⅲ malocclusions(25,13.8%),followed by that of skeletalⅡ(22,12.2%).)and skeletal Ⅰ(19,10.5%).In addition,there is a statistically significant difference between the groups of patients with different sagittal skeletal features.The above studies show that the abnormal upper cervical spine morphology is related to the craniofacial morphology characteristics.At present,there is few studies on the correlation between ponticulus posticus and the craniofacial morphology.Therefore,the objective of this study is to analyze the correlation between different types of ponticulus posticus and craniomaxillofacial tissues.Methods:60 newly-diagnosed adult(aged 18 years or older)Chinese patients in the Department of Orthodontics,Jilin University Hospital of Stomatology from 2016 to2020,were selected and divided into no-ponticulus posticus group,partial-ponticulus posticus group and complete-ponticulus posticus group(20 cases in each group)based on the results of visual inspection of Ponticulus posticus(complete and partial morphology)by visual inspection according to the screening criteria on the patient’s lateral cephalometric radiograph.One-way ANOVA analysis was performed on skull measurement parameters of the three groups to analyze the correlation between different types of ponticulus posticus and Craniomaxillofacial measurement parameters.Results:Compared with patients in the no-ponticulus posticus group,there is statistically significant differences in SNA,ANB,lower facial high angle,and CoGoMe in patients in the partial-ponticulus posticus group(P<0.05),but there was no statistically significant difference in SNB,L1-MP,anterior height,posterior height,CoGo,mandibular length,MP-FH,MP-SN,and anterior facial height/posterior facial height in patients in the partial-ponticulus posticus group(P>0.05);there was statistically significant differences in SNB and L1-MP in patients in the complete-ponticulus posticus group(P<0.05),but there was no statistically significant difference in SNA,ANB,lower facial high angle,anterior facial height,posterior facial height,CoGo,mandibular length,MP-FH,MP-SN,mandibular angle,and anterior facial height/posterior facial height in patients in the complete-ponticulus posticus group(P>0.05);compared with patients in the partial-ponticulus posticus group,there was statistically significant differences in SNA,SNB,ANB,L1-MP,lower facial high angle,and CoGo in patients in the complete-ponticulus posticus group(P<0.05),but there was no statistically significant difference in anterior facial height,posterior facial height,mandibular length,MP-FH,MP-SN,mandibular angle,anterior facial height/posterior facial height in patients in the complete-ponticulus posticus group(P>0.05).Conclusion:1、Compared with patients without ponticulus posticus,patients with partial ponticulus posticus have maxillary protrusion,and there is a tendency of lower facial height and sharped mandibular angle.2、Compared with patients without ponticulus posticus,patients with complete ponticulus posticus have mandibular prognathism,and there is a tendency of retruded lower incisors.3、Compared with patients with partial ponticulus posticus,patients with complete onticulus posticus patients have mandibular retrusion and mandibular mrognathism,and there is a tendency of increased facial height and retruded lower incisors.4、Patients with complete ponticulus posticus have the characteristics of craniomaxillofacial tissue in skeletal Ⅲ patients.5、The types of ponticulus posticus have nothing to do with the vertical facial types.6、The existence and type of ponticulus posticus is correlated with craniomaxillofacial tissue,which provides a reference for orthodontists to increase accuracy in clinical diagnosis and design.