| Objective Submandibular gland fossa undercuts are common in the molar area of mandible lingual side and pose the risk of perforating the lingual cortical bone during insertion of dental implants,which may lead to hemorrhage,infections of the space or obstruction of the upper airways,and so on.At present,there are few research articles on submandibular gland fossa,and there is no uniform measurement standard for the anatomical structure of submandibular gland.As a newly-presented radiological equipment,Cone beam CT(CBCT)was widely used in the whole process of dental implantation.To investigate the anatomic morphology of the submandibular gland fossa in the first molar region and the second molar region by cone beam computed tomography(CBCT)system in order to provide evidence for dental implantation in mandibular molar area.And help to reduce the risk and improve the success rate of surgery.Methods All of the CBCT images used in the study were extracted from the patients with missing mandibular molars,which treated in the oral medical center of Anhui Provincial Hospital between January 2014 and August 2017.A total of 206 patients,consisting of 83 males and 123 females,mean age(46.28±14.68)years;age range: 20 to 81 years,were selected.All the CBCT images were taken by one extensive experience radiologists and scanning voltage was 80 k V,current 5m A.In the 206 cases of CBCT images,a total of 150 the first molar missing cases and 84 the second molar missing cases were obtained.On the coronal image,we connected the most outstanding points in the top and bottom of the lingual undercut,measured the concavity distance at the level of the superior wall of mandibular canal as the submandibular gland depth,and measured the concavity angle at the level of the superior wall of mandibular canal as the submandibular gland angle.SPSS 20.0 software was used to analyze the difference of the proportion,the depth and angle of the submandibular gland fossa in different teeth.Classified data by gender,analyze the proportion,depth and angle of the submandibular gland fossa in different genders in the next step.Taking P<0.05 in the difference was statistically significant.Results 1 There were 88 cases(88/150;58.7%)had a lingual undercut at submandibular gland fossa,and the other 62 patients had a smooth or flat lingual surface in the first molar area.In the second molar area,there was a higher proportion of bone concavity(70/84;83.3%).2 The average depth of the submandibular gland fossa in the first molar was 1.54 + 0.61 mm,and the 95% confidence interval was 1.41~1.67 mm.The average depth in the second molar was 1.80 + 0.81 mm,and 95% confidence interval was 1.61~1.98 mm.3 When grouped by gender,the average depth of the submandibular gland fossa in the first molar was 1.45±0.55mm(M)and 1.64±0.66mm(F),1.97±0.88mm(M)and 1.66±0.72mm(F)in the second molar.4 The average angle of submandibular fossa in the first molar area was 14.70±4.73°,and the 95% confidence interval was 13.70~15.70°.When moving backward,the angle of the undercut increased gradually with the depth deepen.The average angle of submandibular fossa in the second molar of the mandibular second molar was 18.24±4.30°,and the 95% confidence interval was 17.22~19.43°.5 When grouped by gender,the average angle of the submandibular gland fossa was 1.45±0.55mm(M)and 1.64±0.66mm(F)in the first molar,1.97±0.88mm(M)and 1.66±0.72mm(F)in the second molar,respectively.Conclusions 1 The CBCT can measure the depth and the angle of the submandibular gland fossa.2 Submandibular gland fossa concavity is a common clinical finding in the molar area of mandible lingual side which must be avoided during the implantation.The anatomical structure of the submandibular gland fossa undercuts were vary in the different patients.The proportion of the submandibular gland fossa undercuts in the second molar area is higher than the first molar area.3 The depth and angle of the submandibular gland fossa undercuts were gradually increased with the backward walking of the dental arch,and there was no statistically significant difference between the genders. |
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