• Maxillofacial Plastic and Reconstructive Surgery
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• v.42
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• pp.37.1-37.13
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• 2020

Background: The human mandible is variable in shape, size and position and any deviation from normal can affect the facial appearance and dental occlusion. Objectives: The objectives of this study were to determine whether the Sassouni cephalometric analysis could help predict two-dimensional mandibular shape in humans using cephalometric planes and landmarks. Materials and methods: A retrospective computerised analysis of 100 lateral cephalometric radiographs taken at Kingston Hospital Orthodontic Department was carried out. Results: Results showed that the Euclidean straight-line mean difference between the estimated position of gonion and traced position of gonion was 7.89 mm and the Euclidean straight-line mean difference between the estimated position of pogonion and the traced position of pogonion was 11.15 mm. The length of the anterior cranial base as measured by sella-nasion was positively correlated with the length of the mandibular body gonion-menton, r = 0.381 and regression analysis showed the length of the anterior cranial base sella-nasion could be predictive of the length of the mandibular body gonion-menton by the equation 22.65 + 0.5426x, where x = length of the anterior cranial base (SN). There was a significant association with convex shaped palates and oblique shaped mandibles, p = 0.0004. Conclusions: The method described in this study can be used to help estimate the position of cephalometric points gonion and pogonion and thereby sagittal mandibular length. This method is more accurate in skeletal class I cases and therefore has potential applications in craniofacial anthropology and the 'missing mandible' problem in forensic and archaeological reconstruction.

• The korean journal of orthodontics
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• v.52 no.6
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• pp.399-411
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• 2022

Objective: The objective of this randomized clinical trial was to study the skeletal and dental effects of low-level laser therapy (LLLT) along with a miniscrew-assisted expander (Hyrax) after six months of retention. Methods: After sequence generation, concealed allocation, and implementation, 24 female patients were randomly divided (1:1) into two-groups: bone-borne rapid palatal expansion (BBE) without LLLT (n = 12) and BBE with LLLT (n = 12). Eligibility criteria included female patients aged 10-13 years old with bilateral posterior crossbites. Intraoral and extraoral photographs, cone-beam computed tomography images, and digital study models were obtained before expansion and six months after retention. The 7 mm Hyrax appliance was anchored to four palatal mini-screws, which were activated twice daily for 15 days, then locked and kept in place as a retainer. LLLT was performed in the laser group during expansion and retention, according to the guidelines provided. Results: The records of 24 patients were analyzed. According to the post-retention measurements, both groups showed a significant increase in nasal and maxillary widths and total facial height. In the laser group, the Sella-Nasion-Point A and Point A-Nasion-Point B angles and the interpremolar apical distance were significantly increased. Conclusions: Within the limitations of this study, the results suggest that the parameters and protocol of LLLT do not clinically affect the efficiency of BBE in prepubertal and pubertal patients.

• The korean journal of orthodontics
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• v.40 no.6
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• pp.421-431
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• 2010

Objective: This study aimed to verify the intra-individual reproducibility of the natural head position (NHP) in adult Korean patients in the centric relation (CR) position and to prove the inter-individual variability of the Frankfurt horizontal (FH) plane and sella-nasion (SN) line compared to the true horizontal line (THL). In addition, the study aimed to investigate the correlations between linear measurements from A-point and B-point to the nasion true vertical line (NTVL) and angular measurements from A-point and B-point to the SN line. Methods: Two lateral cephalograms were taken of 116 subjects (23 males, 93 females) with CR wax bites in a NHP at a one-week interval. Results: Method errors of three variables and intraclass correlation coefficients of six parameters proved the intra-individual reproducibility of NHP (p < 0.001). The angle of the FH to the THL was not significantly different from $0^{\circ}$ (p > 0.05), but it was clinically variable (SD $3.89^{\circ}$) on the inter-individual level. Conversely, the angle of the SN line to the THL was significantly different from $7^{\circ}$ (p < 0.05). Very low correlation was found between the linear measurements and angular measurements of A-point and B-point (p < 0.01). Conclusions: The NTVL could be a useful reference line for assessing the antero-posterior position of the maxilla and mandible of Korean adult patients in NHP and CR.

• The korean journal of orthodontics
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• v.35 no.6 s.113
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• pp.409-419
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• 2005

Studies for diagnostic analysis using three-dimensional (3D) CT images are recently in progress and needs for 3D craniofacial analysis are increasing in the fields of orthodontics. It is especially essential to analyze the facial soft tissue after orthodontic treatment and orthognathic surgery. In this study 3D CT images of adults with normal occlusion were taken to analyze the facial soft tissue. Norms were obtained from CT images of adults with normal occlusion (12 males, 11 females) using a computer program named V works 4.0 program. 3D coordinate planes were established using soft tissue Nasion as the reference point and a total of 20 reproducible landmarks of facial soft tissue were obtained using the multiple reconstructive sectional images (axial, sagittal and coronal images) of the V works 4.0 program: soft tissue Nasion, Pronasale, Subnasale, Upper lip center, Lower lip center, soft tissue B, soft tissue Pogonion, soft tissue Menton, Endocanthion (Rt/Lt), Alare lateralis (Rt/Lt), Cheilion (Rt/Lt), soft tissue Gonion (Rt/Lt), Tragus (Rt/Lt), and Zygomatic point (Rt/Lt). According to the established landmarks and measuring method, the 3D CT images of adults with normal occlusion were measured and the normal positional measurements and their Net (${\delta}=\sqrt{{X^2}+{Y^2}+{Z^2}}$) values were obtained using V surgery program, In the linear measurement between landmarks, there was a significant difference between males and females except Na' -Sn and En(Rt)-En(Lt). The normal ranges of Na'-Zy, Na'-Ch and Na'-Go' (facial depth) were obtained, which was difficult to measure by two-dimensional (2D) cephalometric analysis and facial photographs. These data may be used as references for 3D diagnosis and treatment planning for patients with malocclusion and dentofacial deformity.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.3
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• pp.412-420
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• 2001

In the growing children with normal occlusion and class III malocclusion who need the early treatment to be helped to diagnose and to set up treatment plan by calculating the mean values of the lateral cephalometric measurements, cephalometric measurements by McNamara alalysis were achieved and compared on both the 84 elementary school children with normal occlusion and 83 class III malocclusion children at the age of 7 to 9 in Kwangju city and the results were as follows: 1. On the boys group, between normal occlusion and class III malocclusion, Effective maxillary length, Maxillomandibular differential, Facial axis, Nasion perpendicualr to pogonion, Point A perp to Mx 1, and A-Pog line to Mn 1 showed significant differences(p<0.05). 2. On the girls group, between normal occlusion and class III malocclusion significant differences were shown in Effective Maxillary length, Maxillomandibular differential, Mandibular plan angle, Nasion perpendicualr to Point A, Point A perp to Mx 1, A-Pog line to Mn 1(p<0.01). 3. There were no significant differences between normal occlusion and class III malocclusion of boys group but significant differences between them of girls group in Effective mandibular length(P<0.01). On the boys and girls group, Effective maxilla length of class III malocclusion was shorter than that of normal occlusion. 4. There were no significant differences between normal occlusion and class III malocclusion both in boys and girls at Anterior lower facial height. 5. There were significant differences between boys and girls both in class III malocclusion and normal occlusion at Anterior lower facial height and Mandibular plane angle(p<0.01).

• The korean journal of orthodontics
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• v.29 no.2 s.73
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• pp.251-265
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• 1999

Various types of horizontal reference planes are used for diagnosis, treatment planning and evaluation of treatment results. But these reference Planes lack accuracy and repro-ducibility, and are mainly for Caucasian. Unlike the adult patients who have completed growth, the horizontal reference planes for growing children may change continuously during growth. Therefore this must be considered in selecting the horizontal reference plane. The purpose of this study was to Investigate the angle formed by the Sella-Nasion(SN) plane and Frankfort-Horizontal(FH) plane and evaluate the angle formed by FH plane and other horizontal reference planes in relation to different skeletal maturity and malocclusion types. 540 subjects with no orthodontic treatment history were chosen, and hand -wrist X-rays and lateral cephalometric X-rays were taken. According to SMA(Skeletal Maturity Assessment) of hand-wrist X-rays, the subjects were classified into 3 skeletal maturity groups : SMI 1-4 for group A, SMI 5-7 for group B and SMI 8-11 for group C. A second classification was made according to cephalometric analysis of lateral cephalograms. The subjects were classified into 3 malocclusion groups : Skeletal Class I, II and III malocclusion group. 10 measurements were evaluated. The results were as follows. 1. The angle formed by the SN plane and FH plane showed no difference among skeletal maturity groups, malocclusion groups, and between .sexes. 2. The angles formed by the SN plane and FH plane were $8.27^{\circ}{\pm}2.31^{\circ}$ for males and $8.59^{\circ}{\pm}2.24^{\circ}$ for females. The average value for females and males was $8.42^{\circ}{\pm}2.28^{\circ}$. 3. The angle formed by the FH plane and palatal plane was almost constant showing no difference among skeletal maturity groups, malocclusion groups, and between sexes($1.09^{\circ}{\pm}3.21^{\circ}$).

• The korean journal of orthodontics
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• v.28 no.2 s.67
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• pp.219-229
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• 1998

The purpose of this study is to define the characteristics of the skeleton and soft tissues of severe adult class III malocclusion. The materials selected for this study were lateral cephalograms of 112 adult class III malocclusion patients with ANB difference below -2 degrees. and the mean age was 22.9 years old. The normal control sampler consisted of lateral cephalograms of 50 adults in normal occlusion and the mean age was 22.1 years old. The Horizontal reference line was FH line and the vertical reference line was nasion perpendicular to FH line. The skeletal and soft tissue characteristics of Class III malocclusion are as follows : 1. In the skeletal profile evaluated by vertical reference line (Nasion perpendicular to FH), the forehead and maxilla was similar to normal, but the mandible was protruded significantly. 2. The soft tissue profile is concave. The thickness of soft tissue covering forehead area and nose is within normal range. but the upper lip is thicker and the nasolabial angle is smaller than normal. The lower lip and inferior labial sulcus is thinner than normal. The degree of eversion of lower lip is lesser than normal. 3. The cranial base of class III malocclusion is shorter and saddle angle is smaller than normal. 4. The location of midface evaluated in relations to cranial base is within normal range but, the length of midface is shorter than normal when compared from the deep portion of the facial skeleton. 5. The location of maxilla in reference to cranial base is within normal range but the length of maxilla was shorter in class III malocclusion. 6. The mandible was protruded, ramus height and body length, gonial angle were greater than normal, and the chin angle was smaller. 7. Upper incisor was proclined, lower incisor was retroclined.

• The Journal of Korean Academy of Prosthodontics
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• v.53 no.4
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• pp.310-317
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• 2015

Purpose: The purpose of this study was to evaluate the validity of reference points for edentulous patient by examining the correlation of teeth and face, and intraoral anatomic landmarks. Materials and methods: We examined a facial outline, length, bizygomatic width, nasion - gnathion length, glabella - nasion distance in 270 men and 280 women satisfied with inclusion criteria from Seoul National School of Dentistry. The shape of maxillary central incisor, mesiodistal crown width and length of maxillary 6 incisors, distance from incisive papilla to labial surface of maxillary central incisor, and perpendicular distance from incisive papilla to intercanine line were measured in the stone model. We analyzed the ratio and relevant relation statistically. Results: The probability on having the same shape of face and the relative same shape maxillary incisor was 55.56% and 46.43% for men and women. The facial length proved to be a more valuable measurement in women in the tooth selection. The ratio of bizygomatic width to mesiodistal width of maxillary central incisor, and the ratio of bizygomatic width to width of maxillary 6 incisors were 16.8 : 1 and 3.0 : 1 and were positively correlated with each other. The distance of the canines from the maxillary incisal papilla was $1.33{\pm}1.28mm$. The distance between the center of the incisal papilla and the labial surface of their maxillary central incisor was $9.23{\pm}1.20mm$. Conclusion: It was showed that anatomical reference points in tooth selection and arrangement for edentulous patient are useful and have validity in our limited study.

• The korean journal of orthodontics
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• v.32 no.5 s.94
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• pp.313-325
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• 2002

Three-dimensional CT imaging is efficient in examining specific structures in the craniofacial area by reproducing actual measurements through minimization of errors from patient movement and image magnification. Due to the rapid development of digital image technology and the expansion of treatment range a need for developing three -dimensional analysis has become urgent. Therefore the purpose of this study was to evaluate the percentage of error and magnification of three-dimensional CT using a dried skull and Vworks $program^{TM}$ (Cybermed Inc., Seoul, Korea) and also to obtain landmarks that are easy to designate and reproduce in three-dimensional images using the Vmorph-proto $program^{TM}$ (Cybermed Inc., Seoul, Korea). The following conclusions were obtained, 1. In the comparison of actual measurements from the dried skull and the three-dimensional image obtained from the Vworks program, the mean error was 0.99mm and the magnification was 1.04%. 2. Clinically useful hard tissue landmarks from three-dimensional images were Supraorbitale, Lateral orbital margin, Infraorbitale, Nasion, ANS, A point, Zygomaticomaxilla, Upper incisor, Lower incisor, B point, pogonion, Menton, PNS, Condylar inner margin, Condylar outer margin, Porion, Condylion, Gonionl, Gonion2, Gonion3, Sigmoid notch and Basion. 3. Clinically useful soft tissue landmarks from three-dimensional images were Endocanthion, Exocanthion, Soft tissue Nasion, Pronasale, Alare lateralis, Upper nostril point, Lower nostril point, Subnasale, Upper lip point, Cheilion, Stomion, Lower lip center, Soft tissue B, Pogonion, Menton and Preaurale. The Vworks program can be considered a clinically efficient tool to produce and measure three-dimensional images. Most of the hard and soft tissue landmarks proposed above are anatomically important points which are also easily reproducible and designated. These landmarks can be beneficial in three-dimensional diagnosis and the prediction of changes before and after surgery.

• The korean journal of orthodontics
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• v.28 no.1 s.66
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• pp.75-83
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• 1998

This study was done to recognize the importance of errors in measurements of cephalometric radiograph and to find the anatomical structures those need special care to select as a reference points through the detection of the systematic errors and estimation of random errors. For this purose, 100 cephalometric radiographs were prepared by usual manner and 61 reference points, and 130 measurement variables were established. Measurement errors were detected and estimated by the comparison of the 25 randomly-selected samples for repeated measurements with the main sample. The following results were obtained : 1. In comparison of the repeated measurements, there were statistical significant differences in 24 variables which were 18.4% of 130 total variables. 2. The frequency of the difference in identification of the reference points between the repeated measurements was very high in the root apex of upper incisor(as), the most posterior wall of maxilla(tu), soft tissue nasion(n'), soft tissue frontal eminence(ft), and ad3 in airway. 3. After correction of reference points marking until the level of below 5% significance, the range of random errors were from 0.67 to 1.71 degree or mm. 4. The variable shown the largest random error was the interincisal angle(ILs-ILi). 5. Measurement errors were mainly caused by the lack of precision in anatomic definitions and obscure radiographic image. From the above results, the author could find the high possibility of errors in cephalometric measurements and from this point, we should include error analysis in all the studies concerning measurments. In is essential to have a concept of error analysis not only for the investigator but also for a reader of other articles.