| Objective:The canalis sinuosus(CS)is a bony canal extending from the infraorbital canal to the anterior part of the maxilla.The anatomic variation of CS in the anterior part of the maxilla is called the accessory canals(ACs).The aesthetic district of maxillary anterior teeth has always been one of the most challenging sites for implant reconstruction.In recent years,with the wide application of cone bundle CT(cone beam computed tomography,CBCT)and the development of a large number of implants in the aesthetic area,the nasopalatine canal(NPC)has received the greatest attention because of its relationship with upper anterior dental implants and its potential clinical significance.However,NPC is not the only anatomical structure carrying nerves and vessels in this area,and the presence of CS and its ACs is also an important consideration when planning implants in the maxillary anterior teeth.Accurate identification of CS and its ACs can reduce the possibility of neurovascular complications during anterior maxillary surgery and improve the prognosis.The purpose of this study was to evaluate the main morphological and morphometric features of CS and its ACs in Shanxi population,and to associate them with sex,age and adjacent anatomical structures,such as buccal bone wall,root of central incisor and NPC,so as to provide anatomical guidance for anterior maxillary implant surgery.Methods:The CBCT data of 336 patients treated in the Stomatology Department of the first Hospital of Shanxi Medical University from June 2021 to June 2022 were analyzed retrospectively.The morphometric characteristics of CS and its ACs were measured by NNT viewer software(sagittal plane:the distance between the end of ACs and buccal bone wall;the distance between ACs and buccal bone wall at root apex level;the distance between ACs end and central incisor root.The distance between ACs and the root apex of central incisor,the diameter of CS,the distance between CS and the root apex of central incisor,the angle between ACs and the long axis of central incisor;axial plane at the end of NPC:ACs diameter,the diameter of NPC,the distance between ACs and NPC,the distance between ACs and central incisor root).The subjects were divided into groups according to sex and age(group A:18-37 years old;group B:38-57 years old;group C:over 58 years old)and NPC type(cylindrical type,hourglass type,funnel type,banana type),the measured values were statistically analyzed.Results:1.CBCT measurement analysis showed that the incidence of ACs in Shanxi population was(46.73%),which was mostly distributed bilaterally and vertically.The palatal side of lateral incisor(51.42%)and central incisor(22.34%)was the main location of ACs distribution.2.The distance between CS and the root apex of central incisor was 10.13±3.19mm,which was linearly correlated with age(R~2=0.353,P<0.001).The distance between the axial plane of the end of NPC and the root of central incisor was 1.53±0.64mm,There were significant differences between the over 58 years group and the 18～37 years group and the38～57 years group(P<0.05).3.The diameter of CS was 1.21±0.35mm.The diameter of CS in cylindrical NPC was significantly larger than that in banana-type(P<0.01),hourglass-type(P<0.01)and funnel-type(P<0.01)NPC.There was significant difference between hourglass-type NPC patients and banana-type NPC patients in the distance between CS and the root apex of central incisor(P<0.05).4.The distance between the end of ACs and the buccal bone wall is 8.70(7.80,9.60)mm;the distance between ACs at the apical level and the buccal bone wall is 5.84±1.63mm;the distance between the end of ACs and the root of central incisor is 2.15(1.50,2.70)mm;the distance between ACs at the root apical level and the root apex of the central incisor is 3.66±1.07 mm;the included angle between ACs and the long axis of the central incisor is 17.67±7.76°;The axial plane of the end of NPC was 0.90(0.80,1.20)mm.The distance between ACs and NPC is 1.90(0.90,2.40)mm.There was no significant difference in all measured values between genders(P>0.05).Conclusion:1.The results of this study showed that there was a high incidence of ACs in the anterior part of maxilla in Shanxi population,and the distance between CS and the root apex of central incisor increased with age.2.The type of NPC has a significant effect on the diameter of CS and the distance between CS and the root apex of central incisor,and the evaluation of CS and NPC is helpful to prevent complications during implantation.3.The relationship between ACs and surrounding anatomical structures may be a potential clinical concern in maxillary anterior dental implant planning.Clinicians should assess the risk more carefully and take appropriate preventive measures before operation. |
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