• Asian Spine Journal
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• v.12 no.6
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• pp.1123-1126
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• 2018

Study Design: Observational study. Purpose: To assess the correlational accuracy between the traditional anatomic landmarks of the neck and their corresponding vertebral levels in Southern Chinese patients. Overview of Literature: Recent studies have demonstrated discrepancies between traditional anatomic landmarks of the neck and their corresponding cervical vertebra. Methods: The center of the body of the hyoid bone, the upper limit of the lamina of the thyroid cartilage, and the lower limit of the cricoid cartilage were selected as representative surface landmarks for this investigation. The corresponding vertebral levels in 78 patients were assessed using computed tomography. Results: In both male and female patients, almost none of the anatomical landmarks demonstrated greater than 50% correlation with any vertebral level. The most commonly corresponding vertebra of the hyoid bone, the lamina of the thyroid cartilage, and the cricoid cartilage were the C4 (47.5%), C5 (35.9%), and C7 (42.3%), respectively, which were all different from the classic descriptions in textbooks. The vertebral levels corresponding with the thyroid and cricoid cartilage were significantly different between genders. Conclusions: The surface landmarks of the neck were not accurate enough to be used as the sole determinant of vertebral levels or incision sites. Intra-operative fluoroscopy is necessary to accurately locate each of the cervical vertebral levels.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.4
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• pp.262-269
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• 2010

Introduction: Accurate diagnosis and treatment planning are very important for orthognathic surgery. A small error in diagnosis can cause postoperative functional and esthetic problems. Pre-existing 2-dimensional (D) chephalogram analysis has a high likelihood of error due to its intrinsic and extrinsic problems. A cephalogram can also be inaccurate due to the limited anatomic points, superimposition of the image, and the considerable time and effort required. Recently, an improvement in technology and popularization of computed tomography (CT) provides patients with 3-D computer based cephalometric analysis, which complements traditional analysis in many ways. However, the results are affected by the experience and the subject of the investigator. Materials and Methods: The effects of the sources human error in 2-D cephalogram analysis and 3-D computerized tomography cephalometric analysis were compared using Simplant CMF program. From 2008 Jan to 2009 June, patients who had undergone CT, cephalo AP, lat were investigated. Results: 1. In the 3 D and 2 D images, 10 out of 93 variables (10.4%) and 11 out 44 variables (25%), respectively, showed a significant difference. 2. Landmarks that showed a significant difference in the 2 D image were the points frequently superimposed anatomically. 3. Go Po Orb landmarks, which showed a significant difference in the 3 D images, were found to be the artificial points for analysis in the 2 D image, and in the current definition, these points cannot be used for reproducibility in the 3 D image. Conclusion: Generally, 3-D CT images provide more precise identification of the traditional cephalometric landmark. Greater variability of certain landmarks in the mediolateral direction is probably related to the inadequate definition of the landmarks in the third dimension.

• Imaging Science in Dentistry
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• v.45 no.4
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• pp.227-232
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• 2015

Purpose: The purpose of this study was to evaluate the influence of methods of establishing the midsagittal reference plane (MRP) on the locations of midfacial landmarks in the three-dimensional computed tomography (CT) analysis of facial asymmetry. Materials and Methods: A total of 24 patients (12 male and 12 female; mean age, 22.5 years; age range, 18.2-29.7 years) with facial asymmetry were included in this study. The MRP was established using two different methods on each patient's CT image. The x-coordinates of four midfacial landmarks (the menton, nasion, upper incisor, and lower incisor) were obtained by measuring the distance and direction of the landmarks from the MRP, and the two methods were compared statistically. The direction of deviation and the severity of asymmetry found using each method were also compared. Results: The x-coordinates of the four anatomic landmarks all showed a statistically significant difference between the two methods of establishing the MRP. For the nasion and lower incisor, six patients (25.0%) showed a change in the direction of deviation. The severity of asymmetry also changed in 16 patients (66.7%). Conclusion: The results of this study suggest that the locations of midfacial landmarks change significantly according to the method used to establish the MRP.

• Journal of The Korean Radiological Technologist Association
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• v.25 no.1
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• pp.138-139
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• 1999

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.1
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• pp.41-51
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• 2005

Statement of problem. Anatomic landmarks have been used in the orientation of occlusal plane and the determination of vertical dimension for edentulous patients. Such as labial vestibules of anterior region and hamular notches, retromolar pads of posterior region are very useful anatomic landmarks for fabrication of occlusion rim because they are to be identified on master casts. Therefore, if average distances between landmarks of maxillae and mandible in dentate subjects are measured and applied, not only occlusal plane but also vertical dimension can be established initially. Purpose. The purpose of this study is to measure vertical distances between anatomic landmarks and to present a guide to the orientation of occlusal plane and the determination of vertical dimension of edentulous patients. Material and method. Upper and lower border-molded casts were made in 93 Korean dentulous subjects, mean age 25 years. Incisal edges of central incisors, bottoms of labial vestibules, hamular notches and the half level of retromolar pads were marked on casts. Measurements of vertical distances from incisal edge of central incisor to the bottom of labial vestibule, between upper and lower bottoms of labial vestibules, from hamular notch to retromolar pad and from hamular notch to the occlusal plane established by the incisal edge of maxillary central incisor and mesiopalatal cusps of both maxillary first molars were made on each cast. Results and conclusion. 1. The mean distance from the incisal edge of central incisor to the bottom of labial vestibule was 20.8mm(SD 1.7) on upper casts and 17.3mm(SD 1.4) on lower casts. 2. The mean distance between both bottoms of labial vestibules of upper and lower casts was 35.0mm(SD 2.7). 3 The mean distance from hamular notch to the half level of retromolar pad was 5.0mm(SD 1.3). 4. The mean distance from hamular notch to occlusal plane was 7.9mm(SD 1.5). 5. Distances from incisal edge of central incisor to labial vestibule on lower casts(P<0.01) and from hamular notch to retromolar pad(P<0.0001) were greater in male than in female.

• Journal of Dental Rehabilitation and Applied Science
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• v.21 no.2
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• pp.105-111
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• 2005

It is essential to establish the suitable position for artificial maxillary anterior teeth, because of not only esthetics, phonetics, mastication, but also optimal position of artificial posterior teeth for the construction of functional and esthetic prostheses. Anatomic landmarks have been used in the arrangement of artificial teeth. Such as incisive papilla and palatal rugae are useful landmarks for positioning occlusal rim and upper anterior artificial teeth because they are relatively stable and to be identified on master cast. Therefore, if average distance between maxillary anterior teeth and landmarks in dentate subjects are measured and applied, appropriate position of occlusal rim can be initially established. In this study, to present a guide to the position of the occlusal rim for upper anterior teeth of edentulous patients, horizontal distance between anatomic landmarks were measured. Maxillary casts were made in 72 Korean dentate subjects. Horizontal distance between central incisor and incisive papilla, between incisive papilla and intercanine line, and between primary palatine rugae and gingival margin of canine were measured on each cast. The results of this study were as follows ; 1. The mean distance from the incisal edge of central incisor to the posterior border of incisive papilla was 12.1 mm (Male 12.2 mm, Female 11.9 mm). 2. The mean distance between posterior border of incisive papilla and intercanine line was 3.5 mm (Male 3.4 mm, Female 3.6 mm / Left 3.6 mm, Right 3.4 mm). 3. The mean distance from the palatal gingival margin of canine to the lateral border of primary palatine rugae was 2.4 mm (Male 2.4 mm, Female 2.4 mm / Left 2.4 mm, Right 2.3 mm). 4. On all measured items, there were no significant differencies in measured values between male and female, and between left and right sides. (P>0.05).

• Imaging Science in Dentistry
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• v.45 no.4
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• pp.213-220
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• 2015

Purpose: The aim this study was to compare the accuracy of orthodontists and dentomaxillofacial radiologists in identifying 17 commonly used cephalometric landmarks, and to determine the extent of variability associated with each of those landmarks. Materials and Methods: Twenty digital lateral cephalometric radiographs were evaluated by two groups of dental specialists, and 17 cephalometric landmarks were identified. The x and y coordinates of each landmark were recorded. The mean value for each landmark was considered the best estimate and used as the standard. Variation in measurements of the distance between landmarks and measurements of the angles associated with certain landmarks was also assessed by a subset of two observers, and intraobserver and interobserver agreement were evaluated. Results: Intraclass correlation coefficients were excellent for intraobserver agreement, but only good for interobserver agreement. The least reliable landmark for orthodontists was the gnathion (Gn) point (standard deviation [SD], 5.92 mm), while the orbitale (Or) was the least reliable landmark (SD, 4.41 mm) for dentomaxillofacial radiologists. Furthermore, the condylion (Co)-Gn plane was the least consistent (SD, 4.43 mm). Conclusion: We established that some landmarks were not as reproducible as others, both horizontally and vertically. The most consistently identified landmark in both groups was the lower incisor border, while the least reliable points were Co, Gn, Or, and the anterior nasal spine. Overall, a lower level of reproducibility in the identification of cephalometric landmarks was observed among orthodontists.

• Imaging Science in Dentistry
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• v.51 no.3
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• pp.299-306
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• 2021

Purpose: This study aimed to propose a fully automatic landmark identification model based on a deep learning algorithm using real clinical data and to verify its accuracy considering inter-examiner variability. Materials and Methods: In total, 950 lateral cephalometric images from Yonsei Dental Hospital were used. Two calibrated examiners manually identified the 13 most important landmarks to set as references. The proposed deep learning model has a 2-step structure-a region of interest machine and a detection machine-each consisting of 8 convolution layers, 5 pooling layers, and 2 fully connected layers. The distance errors of detection between 2 examiners were used as a clinically acceptable range for performance evaluation. Results: The 13 landmarks were automatically detected using the proposed model. Inter-examiner agreement for all landmarks indicated excellent reliability based on the 95% confidence interval. The average clinically acceptable range for all 13 landmarks was 1.24 mm. The mean radial error between the reference values assigned by 1 expert and the proposed model was 1.84 mm, exhibiting a successful detection rate of 36.1%. The A-point, the incisal tip of the maxillary and mandibular incisors, and ANS showed lower mean radial error than the calibrated expert variability. Conclusion: This experiment demonstrated that the proposed deep learning model can perform fully automatic identification of cephalometric landmarks and achieve better results than examiners for some landmarks. It is meaningful to consider between-examiner variability for clinical applicability when evaluating the performance of deep learning methods in cephalometric landmark identification.

• Archives of Plastic Surgery
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• v.47 no.5
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• pp.483-486
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• 2020

Midline clefts of the upper lip are rare, and it is therefore important that surgeons have access to a methodical approach for when these presentations are encountered. We adapted principles of the anatomic subunit approximation for unilateral cleft lip, to the repair of midline clefts. The overt use of anatomic landmarks to define the repair results in a design that inherently adjusts to varying degrees of clefts and can accommodate asymmetries. The "measure twice, cut once" style is an advantage to new surgeons and to surgeons who seldom encounter this presentation. We describe the details of surgical repair in the context of a patient with Pai syndrome and associated nasal hamartomas that resulted in nasolabial asymmetry. This is the first report of surgical outcome following treatment of Pai syndrome and includes early and 5-year follow-up. The system of repair that we describe is applicable to both symmetric and asymmetric midline clefts.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.28 no.3
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• pp.222-228
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• 2006

Various methods have been used in the past to indirectly analyze the craniofacial region. Among these, the lateral and posterior-anterior cephalometircs are used for the evaluation of the dentofacial deformities. However, cephalometircs create inaccuracies because of the inherent enlargement and distortion of the image. The interpretation of cephalometric films is also problematic: the number of anatomic landmarks that can be identified accurately is limited, and the overlap of structures on a radiograph making locating these landmarks difficult. To overcome these problems, computed tomography(CT) has been recommended as an useful modality in the diagnosis, surgical planning, and follow-up of craniofacial anomalies. There is no significant enlargement or distortion of the image, overlap of structure, or tracing error. And the number of anatomic landmarks is vast. The purpose of this study was to examine the orbit and midfacial region using Occlusal Maxillary CT, consisted of slices parallel to the occlusal plane. Based on these CT scan, we provide the data that could be applied to monitor an individual patient's skeletal pattern and the guide to the maxillary osteotomy.