Measurement of buccolingual inclination of posterior teeth and the curve of Wilson in patients with different sagittal skeletal patterns using cone-beam computed tomography / 口腔疾病防治

Objective@# To study the buccolingual inclination of posterior premolars and molars and the curve of Wilson in patients with different sagittal skeletal patterns, to explore the compensation mechanism of horizontal inclination of posterior teeth in patients with different sagittal skeletal patterns and to provide a reference for the control of posterior tooth inclination in the treatment of bone malocclusion.@*Methods@#This study was reviewed and approved by the Ethics Committee, and informed consent was obtained from the patients. Ninety CBCT scans of adults and ninety scans of adolescents before orthodontic treatment were evaluated in this cross-sectional study. There were 30 skeletal Class I, Class Ⅱ, and Class Ⅲ patients in the adult group and adolescent group. The inclination angles of posterior teeth and the curve of Wilson of first and second molars were measured, and data were analyzed between adolescents and adults with different sagittal skeletal patterns.@*Results @#Compared with skeletal Class Ⅰ adult patients, the upper posterior molar inclination of skeletal Class Ⅱ patients was significantly lower, and the lower posterior molar inclination was significantly higher. Compared with skeletal ClassⅠ adult patients, the upper posterior molar inclination of skeletal Class Ⅲ adult patients was higher, and the lower posterior molar inclination was significantly lower. The Wilson curve of the second molar in skeletal Class Ⅱ adult patients was significantly higher than that in the other groups. Compared with skeletal ClassⅠ adolescent patients, skeletal Class Ⅲ adolescent patients had a significantly higher upper posterior molar inclination; however, no difference was found between the inclination of the posterior teeth between skeletal Class Ⅰ, Class Ⅱ and Class Ⅲ adolescent patients. Comparing adolescent and adult samples, in skeletal Class Ⅱ patients, adults showed more lingual inclination than adolescents in the upper posterior teeth and less lingual inclination in the lower posterior teeth except for the mandibular first molar. Comparing adolescent and adult samples, in skeletal Class Ⅲ patients, adults showed more lingual inclination than adolescents in the lower posterior teeth except for the mandibular second molars and showed no difference in the upper posterior teeth.@*Conclusions@#The inclination of the posterior teeth and the curve of Wilson show significant differences between the three sagittal skeletal patterns. Compared with those of skeletal Class Ⅰ patients, the posterior teeth of skeletal Class Ⅱ patients show more lingual inclination in the upper arch and less lingual inclination in the lower arch. Meanwhile, posterior teeth of skeletal Class Ⅲ patients show more lingual inclination in the lower arch and maintain the inclination in the upper arch.

Cone-beam CT evaluation of temporomandibular joint in skeletal class Ⅱ female adolescents with different vertical patterns / 北京大学学报(医学版)

OBJECTIVE@#To compare temporomandibular joint (TMJ) morphology and position among skeletal class Ⅱ female adolescents with different vertical patterns using cone-beam CT (CBCT).@*METHODS@#Diagnostic CBCT images of 80 female patients aged 11 to 14 years were assessed retrospectively. According to subspinale-nasion-supramental angle (ANB) and Frankfort horizontal plane-gonion-gnathion angle (FH-GoGn), the participants were categorized into four groups (20 subjects each), i.e. class Ⅰ normal angle (group 1, 0°≤ANB < 4°, 22°≤FH-GoGn≤32°), class Ⅱ low (group 2, ANB≥4°, FH-GoGn < 22°), normal (group 3, ANB≥4°, 22°≤FH-GoGn≤32°) and high angle (group 4, ANB≥4°, FH-GoGn > 32°). Cephalometrics, morphology and position of TMJ were measured in Dolphin software. Using paired-samples t test to analyze TMJ symmetry, One-way analysis of variance (One-way ANOVA) and Chi-square tests to detect differences among the groups. The correlations between cephalometrics and TMJ measurements were also analysed within the skeletal class Ⅱ patients.@*RESULTS@#(1) Analysing TMJ morphologic symmetry, some measurements differed statistically although the mean diffe-rences were negligibly relative to their values. No statistically significant difference was found among the groups though group 4 showed the highest probability of condylar position asymmetry (65%). (2) Comparing group 1 with group 3, statistical difference was found in condylar position (χ2=6.936, P < 0.05) instead of morphologic measurements. Anterior and concentric condylar position were more frequently observed in group 1, yet posterior position was more prevalent in group 3. (3) In groups 2, 3, and 4, statistically, group 2 had the deepest glenoid fossa depth (H2&4=10.517, P=0.002), biggest superior (LSD-t2&3=3.408, LSD-t2&4=5.369, P < 0.001) and lateral (LSD-t2&3=2.767, LSD-t2&4=3.350, P=0.001) joint spaces, whereas group 4 showed the shortest condylar long axis diameter (H2&4=13.374, P < 0.001), largest glenoid fossa vertical distance (LSD-t2&4=4.561, P < 0.001, LSD-t3&4=2.713, P=0.007), smallest medial (LSD-t2&4=-4.083, P < 0.001) and middle (LSD-t2&4=-4.201, P < 0.001) joint spaces. The posterior condylar position proportion gradually increased from groups 2 to 3 to 4. Correlation analysis revealed ANB correlated with anterior joint space positively (r=0.270, P=0.037) and condylar long axis angle negatively (r=-0.296, P=0.022). FH-GoGn correlated with superior (r=-0.488, P < 0.001), posterior (r= -0.272, P=0.035), mesial (r=-0.390, P=0.002), middle (r=-0.425, P=0.001), and lateral (r=-0.331, P=0.010) joint spaces, articular eminence inclination (r=-0.259, P=0.046), as well as condylar long axis diameter (r=-0.327, P=0.011) negatively, and glenoid fossa depth (r=0.370, P=0.004) positively.@*CONCLUSION@#TMJ characteristics of skeletal class Ⅱ sagittal pattern mainly reflected in condylar position rather than morphology. TMJs of different vertical patterns differed more in joint spaces, position of condyle and glenoid fossa than in morphologic measurements. Vertical position of glenoid fossa and proportion of posterior condyle increased gradually from hypodivergent to hyperdivergent. Highest glenoid fossa position, maximum ratio of posterior positioned condyle, smallest joint spaces, shallowest glenoid fossa depth, and narrowest condylar long axis diameter were found in skeletal class Ⅱ high angle group, which means that patients with this facial type have considerable joint instable factors, and we should especially pay attention when orthodontic treatment is carried out on them.

Analysis of crown-root morphology in canines based on cone-beam computed tomography / 口腔疾病防治

Objective@# To compare the morphology of the crown roots of upper and lower canines in patients with skeletal Class Ⅰ, Ⅱ, and Ⅲ malocclusions by CBCT and to provide guidance for the clinical treatment of orthodontics. @*Methods@#Randomly selected patients with permanent occlusal malocclusion who had undergone CBCT and X-ray skull lateral radiographs were Classified according to the ANB angle size: group Ⅰ, group Ⅱ, and group Ⅲ. Three-dimensional reconstruction was used to obtain the median sagittal section images of the right upper and lower canines. The crown root angle, crown root deflection distance, and lip tangent angle at the center of the clinical crown were used as indicators for measurement and analysis with the use of AutoCAD software.@*Results @#The difference in the crown-root skew distance between different sagittal face types, including upper canines (F=3.335, P=0.042), lower canines (F=3.745, P=0.029) crown root angles and upper canines (F=3.312, P=0.043), and lower canines (F=3.641, P= 0.032), was statistically significant (P < 0.05). The crown root angle of the maxillary canine in group Ⅰ was larger than that in group Ⅱ, and the deflection distance of the crown root was negative and the absolute value was lager in group Ⅰ than in group Ⅱ (P < 0.05). The deflection distance was positive and greater in group Ⅲ than in groups Ⅰ and Ⅱ (P < 0.05). There was no significant difference in the maxillary canine crown-labial tangent angle between the different sagittal facial misalignment groups (P > 0.05).@*Conclusion@#Differences in the morphology of canines were found among subjects with skeletal Class Ⅰ, Ⅱ, and Ⅲ malocclusions. The root of the upper canine in Class Ⅰ malocclusions was relatively closer to the labial side of the crown than that in Class Ⅱ malocclusions. The root of the lower canine in Class Ⅲ malocclusions was the closest to the lingual side of the crown among the three Classes.

Relación entre el patrón esqueletal y la posición cráneo-cervical / Relationship between the skeletal pattern and the cranial-cervical position

Introducción: Los problemas posturales se inician, en la mayoría de los casos, en la infancia, por lo tanto en período de crecimiento una actitud postural alterada compromete el equilibrio cefálico y la posición de la mandíbula pudiendo originar malocluciones. Objetivo: Analizar si existe relación entre el ángulo cráneo-cervical y el patrón esqueletal en una población infantil. Material y métodos: Se evaluaron 70 pacientes con telerradiografía de cráneo de perfil con exámenes cefalométrico de Ricketts con patrón esqueletal de clase I, II y III (Campo II relación cráneo-mandibular, factor 7 convexidad) y el cefalograma de Rocabado, utilizando el ángulo cráneo-vertebral. Resultado: Tanto el sexo como el patrón esqueletal son significativos, su interacción no lo es. A su vez, la edad no resulta significativa. Conclusión: En el presente estudio se encontró que existe relación significativa entre el ángulo cráneo-cervical y el patrón esqueletal (AU)

Introduction: Postural problems begin in most cases, in childhood, therefore during growth an altered postural attitude compromises the cephalic balance and jaw position causing posible malocclucion. Objective: It is to present the correlation between the skull and cervical angle skeletal pattern in a child population. Material and methods: 70 patients were evaluated with teleradiography cephalometric profile tests Ricketts skeletal pattern with class I, II and III (Field II craniomandibular relationship, Factor 7 convexity) and cephalogram Rocabado, using the craniovertebral angle. Result: Both sex and skeletal pattern are significant and their interaction is not. In turn, age is not significant. Conclusion: In the present study it was found that there is a statistically significant relationship between the cranial-cervical angle, and the skeletal pattern (AU)

Evaluation of Upper Airway Depth with Different Anteroposterior Skeletal Patterns in Children / 대한소아치과학회지

The respiratory function is relevant to the craniofacial growth and orthodontic diagnosis. The size of the pharyngeal airway was measured in lateral cephalometric view in children visited Kyung Hee University Hospital from January 2015 to August 2017. A total of 74 healthy children (36 boys and 38 girls) aged 7 - 11 years (mean, 8.5 years) with a normodivergent facial pattern were divided into three groups according to anteroposterior jaw relation measuring A point-Nasion-B point (ANB) angle. Lateral cephalometric data were used to measure the airway dimensions. The dimensions of the middle airway were significantly lower, reducing the upper airway space, in large ANB angle group than in other children, suggesting that children with large ANB angle have narrower airway space than others.

Pharyngeal Airway Dimensions in Skeletal Class II Young Adolescents : Cephalometric Study / 대한소아치과학회지

This study aimed to evaluate the nasopharyngeal and oropharyngeal dimensions of the patients with skeletal class II division 1 or division 2 patterns during the pre-peak, peak, and post-peak growth periods for comparison with a skeletal class I control group (79 for pre-peak, 40 for peak, 40 for post-peak). Total 159 lateral cephalograms (70 for skeletal class I, 51 for skeletal class II, division 1, and 38 for skeletal class II, division 2) were selected.The growth of anteroposterior dimension of the pharyngeal airway were statistically significant among growth periods. The dimension for the nasopharyngeal and oropharyngeal airway space was the smallest in the division 1 skeletal class II group followed by class II division 2 and skeletal class I.

Mandibular condyle dimensions in Peruvian patients with class II and class III skeletal patterns

OBJECTIVE: to compare condylar dimensions of young adults with class II and class III skeletal patterns using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: 124 CBCTs from 18-30 year-old patients, divided into 2 groups according to skeletal patterns (Class II and Class III) were evaluated. skeletal patterns were classified by measuring the ANB angle of each patient. the anteroposterior diameter (A and P) of the right and left mandibular condyle was assessed from a sagittal view by a line drawn from point A (anterior) to P (posterior). the coronal plane allowed the evaluation of the medio-lateral diameter by drawing a line from point M (medium) to L (lateral); all distances were measured in mm. RESULTS: In class II the A-P diameter was 9.06±1.33 and 8.86±1.56 for the right and left condyles respectively, in class III these values were 8.71±1.2 and 8.84±1.42. in class II the M-L diameter was 17.94±2.68 and 17.67±2.44 for the right and left condyles respectively, in class III these values were 19.16±2.75 and 19.16±2.54. CONCLUSION: class III M-L dimensions showed higher values than class II, whereas these differences were minimal in A-P.

CBCT measurement and analysis of morphological characteristic of oropharyngeal airway with different sagittal skeletal pattern in high angle adults / 口腔疾病防治

Objective@# To investigate the relationship between the morphology of the oropharyngeal airway and the maxillofacial skeletal morphology by comparing the three-dimensional morphology of the oropharyngeal airway in different sagittal features of the high angle adult. @*Methods@#60 high angle adults aged 18 to 36 years were divided into 3 groups based on their ANB angles, there were 20 adults in each group, the number of males were equal to females. The In vivo Dental 5.1 software for reconstructing the CBCT image of each one was used, the middle sagittal plane and axial plane in coronal, sagittal and axis view was adjusted, then the distances, volumes and minimum cross-sectional areas were measured. The differences among 3 groups and between different gender were compared.@*Results @#There was statistical difference in W-ETP among 3 groups (P< 0.05). There were statistical difference in H-GP、H-Total、W-PNSP、W-ETP、V-GP、V-Total (P< 0.05) between males and females, and these measurements of males were bigger than of females.@*Conclusion @#The difference of the size and shape of the oropharyngeal airway of high angle adults among different sagittal skeletal patterns was mainly reflected in the lowest width of glossopharyngeal airway, the oropharyngeal airway of males was bigger and longer than females.

The effects of activator treatment on the hard and soft tissue profile of different skeletal patterns / 实用口腔医学杂志

Objective:To evaluate skeletal,dentoalveolar and soft tissue profile changes by activator therapy in patients with different skeletal patterns of Class Ⅱ1 malocclusions.Methods:22 subjects(10 girls,12 boys,mean age 11.5 ±0.67 years) in the mixed or early permanent dentition,were included and divided into low angle(n =15) and average angle(n =7) groups on the basis of skeletal pattern.All patients were treated with a traditional activator.The skeletal,dentoalveolar and soft tissue profile changes were compared on lateral cephalograms before and after treatment.Statistical analysis was performed with t-test of SPSS 13.0 at a level of significance of P ＜ 0.05.Results:Activator treatment in these growing patients resulted in a correction of the skeletal Class Ⅱ relationship (decrease of ANB,Wits and NA-Pg),an advancement of the mandibular structures(increase of Co-Pg and L1-APg),and changes of the teeth(increase of L6-MP).The changes of Wits,NA-Pg and L1-APg value of low and average angle groups were 1.34° ± 1.82 ° and 3.50 ° ± 1.77°,(3.06 ± 2.00) mm and (5.80 ± 3.17) mm,(-1.16-± 1.74) mm and (-2.83 ± 1.48) mm respectively(P ＜0.05).No statistical significance was found in the soft tissue profile changes whether intra-class or inter-group comparison.Conclusion:The activator appliance is effective in treating growing patients with mandibular deficiency,and mandibular reconstruction,in patients with average angle it is more effective than in those with low angle.

A lateral cephalometric study of perioral soft tissue of the sbjects with ClassⅡDivisionⅠand various verti-cal patterns / 实用口腔医学杂志

Objective:To study the perioral soft tissue characteristics of the subjects with ClassⅡDivisionⅠand various vertical pat-terns. Methods:Lateral cephalograms of 90 adults ( half men, half women) were divided into 3 groups based on GoGn-SN angle:low angle, normal angle and high angle(n=30). The perioral soft tissues were measured and compared for the determination of the vertical skeletal variables influencing soft tissue characteristics. Results: The subjects with low angle showed significantly smaller values than those with high angle for basic lower lip thickness and lower lip length(P<0. 05). Most measurements of soft tissue thickness were greater in men than in women in all groups, especially for basic upper lip thickness and upper lower lip thickness(P<0. 05). Conclu-sion:Orthodontists need to pay more attention to the differences of perioral soft tissue in the subjects with various vertical patters to ob-tain balance of the facial harmony in orthodontic treatment.

Evaluation of buccolingual inclination of posterior teeth in different facial patterns using computed tomography.

Background and Objective: Buccolingual inclination of teeth is an essential factor in establishing good occlusion. The objective of this study was to evaluate the buccolingual inclination of molar teeth in different vertical skeletal patterns by using computed tomography scans. Materials and Methods: Coronal section of the jaws obtained from computed tomograms were used to measure the buccolingual inclination of the long axis of the molars relative to their skeletal base. Forty male adult individuals with class I dental occlusion were selected. They were classified as short (Group 1), average (Group II), and long faced (Group III) as per their skeletal patterns measured by GoGn-SN, FH-MP, Y-axis and facial height index in cephalograms. Statistical Analysis: ANOVA and Tukey HSD tests were applied to calculate if there were any significant differences in the mean molar inclination between the groups. Pearson's coefficients of correlation were calculated between the facial parameters and tooth inclination. Results: The differences in the mean molar inclination between the short, average, and long faced groups is significant for mandibular 1 st and 2 nd molars and maxillary 2 nd molars. Conclusion: Variations in mean molar inclination values are observed between short, average, and long faced groups.

Comparisons of occlusal force according to occlusal relationship, skeletal pattern, age and gender in Koreans / 대한치과교정학회지

OBJECTIVE: The aim of this study was to evaluate the occlusal force and contact area and to find its associating factors in Koreans. METHODS: Occlusal force and contact area in maximum intercuspation were measured using the Dental Prescale(R) system in 651 subjects (15 with normal occlusion, 636 with various malocclusions divided into subgroups according to the skeletal pattern, Angle's molar relationship, age and gender). RESULTS: Occlusal force of the normal occlusion group (744.5 +/- 262.6 N) was significantly higher than those of the malocclusion group (439.0 +/- 229.9 N, p < 0.05). Occlusal force was similar regardless of differences in ANB angle or Angle's molar classification, however the increase in vertical dimension significantly reduced occlusal force (p < 0.05). CONCLUSIONS: Occlusal force was significantly lower in the malocclusion group compared to the normal occlusion group, and in females compared to males, but it was not affected by age, antero-posterior skeletal pattern or molar classification. Although a hyperdivergent facial pattern indicated lower occlusal force compared to a hypodivergent facial pattern, the differences in skeletal pattern were not the primary cause of its decrease, but a secondary result induced by the differences in occlusal contact area according to the facial pattern.

Alterações cefalométricas presentes em crianças e adolescentes com desordens da ATM nas diferentes classificações sagitais de má oclusão / Cephalometric changes present in children and adolescents with TMJ disorders with different classes of malocclusions

INTRODUÇÃO: o acometimento da ATM por alterações degenerativas e deslocamentos do disco articular demonstrou ser um fator de risco para a identificação de indivíduos com padrões hiperdivergentes de crescimento facial. OBJETIVOS: avaliar diferenças entre as médias encontradas para as variáveis cefalométricas em crianças com DTM articular e grupo controle, nas diferentes classificações sagitais de má oclusão (Classe I, II e III de Angle). MÉTODO: foram incluídos crianças e adolescentes com idade máxima de 17 anos, divididos em grupo experimental (n = 30) com diagnóstico de DTM articular, segundo o eixo I do RDC/TMD para crianças e adolescentes, igualmente divididos em 3 sub-grupos (n= 10) de acordo com a classificação da má oclusão presente e grupo controle (n = 30) sem DTM, pareados por gênero, índice de maturidade esquelética vertebral cervical e classificação da má oclusão. Foram traçadas telerradiografias laterais e as estruturas craniofaciais e suas relações foram divididas em: base do crânio, maxila, mandíbula, relações intermaxilares, relações esqueléticas verticais e relações dentárias. As diferenças encontradas entre as médias, para cada uma das variáveis, foram avaliadas pela aplicação do teste estatístico t de Student para amostra independentes. RESULTADOS: o grupo experimental Classe I apresentou S.N.Ar (p = 0,05) aumentado, o grupo experimental Classe II apresentou S.N.Ar (p = 0,006) e NperpA (p = 0,037) diminuídos e S.Ar.Go (p = 0,045) aumentado e o grupo experimental Classe III apresentou N.A.P (p = 0,045), 1.NB (p = 0,001) e 1-NB (p = 0,017) aumentados e 1.1 (p = 0,004) diminuído, todos em relação aos seus respectivos controles CONCLUSÃO: as diferenças foram mais significantes nos pacientes com má oclusão de Classe II e de Classe III.

INTRODUCTION: the involvement of TMJ through degenerative changes and displacements of the articular disc proved to be an important risk factor when identifying individuals with vertical facial growth patterns. PURPOSES: to evaluate differences between cephalometric variables in children with articular TMD and a control group, checking the variations in relation to the different patterns of malocclusion (Class I, II and III). METHOD: the study included children and adolescents of up to a maximum age of 17, who were divided up into an experimental group (n=30) diagnosed with articular TMD, diagnosed in accordance with the RDC/TMD axis I for children and adolescents, and a control group (n=30) without TMD, further paired by gender, stage of cervical vertebral skeletal maturity and class of malocclusion. Lateral cephalogram was carried out and both the craniofacial structures and their relations were separated into: the cranial base, maxillary, mandible, intermaxillary relations, vertical skeletal relations and dental relations. The differences found between the means, for each of the variables, were evaluated through the application of the Student t statistical test for independent samples. RESULTS: the Class I experimental group presented increased S.N.Ar (p=0.05). The Class II experimental group presented reduced S.N.Ar (p=0.006) and NperpA (p=0.037) and increased S.Ar.Go (p=0.045). The Class III experimental group presented increased N.A.P (p=0.045), 1.NB (p=0.001) and 1-NB (p=0.017) and reduced 1.1 (p=0.004). CONCLUSION: differences were more significant in those patients who presented Class II and III malocclusions.

Effects of activator treatment on different skeletal patterns in growing class II malocclusion patients / 대한치과교정학회지

OBJECTIVE: To establish proper diagnosis and treatment plan for skeletal Class II malocclusions, some important factors to consider are the patient's skeletal morphology, prognosis as well as the treatment effects. Therefore, the present study analyzed the effects of activator treatment on different skeletal patterns in growing Class II malocclusion patients. METHODS: A total of 116 patients (53 boys & 63 girls) in the experimental group were treated with the activator appliance. The experimental group was classified into either hyperdivergent or hypodivergent groups according to articular and gonial angles. RESULTS: Patients with hypodivergent growth patterns showed good effects of activator treatment. CONCLUSION: It seems conceivable that through classifying adolescent Class II malocclusion patients into different skeletal patterns, activator treatment effects may be predicted during the diagnosis and treatment planning stage.

Relationship between maximum bite force and facial skeletal pattern / 대한치과교정학회지

The purpose of this study was to measure maximum bite force and to investigate its relationship with anteroposterior, vertical, and transverse facial skeletal measurements. From among the dental students at the College of Dentistry, forty subjects (26 male and 14 female) were selected. With two sets of strain gauge, maximum bite force at the right and left first molars and anterior teeth was measured in the morning and afternoon. After taking lateral and posteroanterior cephalograms, fifty and nineteen variables were evaluated, respectively. Paired t-tests and an independent t-test were done and correlation coefficients were obtained. 1. The maximum bite force at the first molars was 68.0+/-13.9 kg in males and 55.6+/-10.5 kg in females (p0.05). 3. Significant difference was observed between the strong bite force group and the weak bite force group in some cephalometric and other measurements (p<0.05). N-S-Ar, S-Ar-Go, FH-H1, MPA and MMO showed a significant difference in posterior maximum bite force (P). N-S-Ar and FH-H1 also showed a significant difference in anterior maximum bite force (A). 4. Several cephalometric variables showed some correlation with maximum bite force (p<0.05). N-S-Ar, S-Ar-Go, UGA, FH-H6, FH-H1, body weight and MMO were significantly correlated with posterior maximum bite force (P). Go-Me, P-1 and IMPA were significantly correlated with anterior maximum bite force (A).

Airway size in malocclusions with hyperdivergent skeletal pattern / 대한치과교정학회지

The pharynx have significant locations and functions because it forms a part of the unit in which respiration and deglutition are carried out. Because of the closed relationship between the pharynx and the dentofacial and craniofacial structure, many studies are carried out on this subjects. The purpose of this study were to compare the airway size including pharynx, soft palate, tongue and hyoid bone between normal and hyperdivergent skeletal pattern and to evaluate the change of those size in different age. The sample of this study were consisted of 51 subjects in normal group, 52 subjects in hyperdivergent group. Each was divided into two subgroups by age ; child group(9-12yr old) and adult group(18yr old over). The lateral cephalometric radiographs were taken and the distance, angle and ratio of the facial skeleton, pharynx, soft palate, tongue and hyoid bone were measured and evaluated statistically. The result obtained were summarized as follows : 1. SN-Mn angle, FMA, and Pal-Mn angle were significantly larger in child group than adult group, but the lower anterior facial height(LAFH) and facial height ratio(FHR) were significantly smaller in child group than adult group. Occlu-Mn angle was significantly steep in hyperdivergent group than normal, but not significantly different between child group and adult group. 2. Hyperdivergent group and child group had the stronger correlation between SN-Mn angle, FMA, Pal-Mn angle, LAFH and FHR and airway size than normal group and adult group. Hyperdivergent child group had significant negative correlation between SN-Mn angle, FMA, Pal-Mn angle and sagittal skeletal dimension of nasopharynx and sagittal depth of nasopharyngeal lumen. Significant positive correlation were seen between LAFH and vertical measurement of airway. 3. There was no difference of the linear measurement of airway size between hyperdivergent group and normal group. 4. Adult group had smaller posterior pharyngeal wall, larger nasopharyngeal depth longer nasopharyngeal height and longer pharyngeal length than child group. 5. The sagittal measurement of hyoid bone had no difference between child group and adult group. But adult group had larger vertical measurement of hyoid bone than child group.

Classification of the skeletal variation in the normal occlusion / 대한치과교정학회지

The purposes of this study were to classify the anteroposterior and vertical skeletal pattern of normal occlusion samples into specific types with factor and hierarchical cluster analysis, and to evaluate the range and limit of skeletal relationships that permit the establishment of normal occlusion via natural dentoalveolar compensation. Lateral cephalograms of 294 normal occlusion samples were measured, as selected from 15,836 persons through a community dental health survey who cooperated in record taking. Using a factor analysis, two factors representing anteroposterior and vertical skeletal relationships were extracted from 18 skeletal measurements. Then cluster analysis classified the skeletal patterns into nine types. The means and the standard deviations of 8 anteroposterior skeletal measurements and 10 vertical skeletal measurements were determined and comparisons of these measurements among the types were performed. The results obtained in this study showed that the range of normal occlusion included very diverse anteroposterior and vertical skeletal relationships.

Dentoalveolar Compensation according to Skeletal Patterns of Normal Occlusion / 대한치과교정학회지

In general, Orthodontists make problem lists and treatment plans based on norms of several cephalometric standards. But consideration of dentoalveolar compensation, which tends to maintain normal dental arch relationship in various skeletal jaw relationships, helps orthodontists make more individualized treatment objectives and plans. The purpose of this study was to classify skeletal pattern of normal occlusion samples by cluster analysis and to investigate the dentoalveolar compensation according to skeletal patterns. The subjects were consisted of 125 subjects who were normal occlusion samples at Seoul National University Dental Hospital, Department of Orthodontics. Lateral cephalograms in centric occlusion were traced and digitized. The skeletal patterns of normal occlusion samples were classified into three horizontal groups and three vertical groups by cluster analysis and ANOVA on the skeletal and dentoalveolar measurements among the groups were carried out. The results were as follows; 1. Anteroposterior and vertical skeletal relationships of normal occlusion samples were very variable. 2. As the mandibular position was anterior to the maxilla, the maxillary incisors inclined more labially, the mandibular incisors more lingually, and the occlusal plane was flattened due to the anteroposterior dentoalveolar compensation. 3. As the vertical skeletal pattern was prominent, the upper anterior dentoalveolar height was increased, the lower posterior dentoalveolar height was decreased and upper posterior teeth was uprighted to the palatal plane and lower incisors and lower posterior teeth to the mandibular plane. 4. Lower incisors were more strongly associated with the dentoalveolar compensation than upper incisors according to the anteroposterior and vertical skeletal relationship.

A study on correlations between tongue with skeletal pattern and intermaxillary space in Class II malocclusion adult patients / 대한치과교정학회지

This study was designed to evaluate the correlations between tongue with skeletal pattern and intermaxillary space in Class II malocclusin adult patients. Craniofacial skeletal pattern was analyzed on the lateral cephalometric radiograph and the subjects were divided two groups by facial ratio, the 30 subjects of hyperdivergent group and the 30 subjects of hypodivergent group. The size and posture of tongue and intermaxillary space were measured on the lateral cephalometric radiograph. These data were statistically analyzed to examine significant differences between both groups and compared the correlation between tongue with skeletal measurements and intermaxillary space in each group. The results of the study were as follows. : 1. In comparison of th tongue and intermaxillary space, the measurement of TS/IS showed significantly larger in hyperdivergent group and PIH and IS showed significantly larger in hypodivergent group. There were no statistically significant differences in the measurements of the height and posture of tongue. 2. In correlation between tongue with craniofacial skeletal measurements, the length and height of tongue showed the highest correlation with AFH(anterior facial height) in both groups(p<0.011). And that measurements showed high correlation with PFH(posterior facial height) in hypodivergent group. 3. In both groups, most measurements of tongue showed high correlation with intermaxillary space and the height and space of tongue showed high correlation with AIH and PIH(p<0.01).

A roentgenographic study on the extraction index in Korean adolescent / 대한치과교정학회지

To extract or not to extract permanent teeth for the correction of malocclusion has been a great debate in the history of orthodontics, and there is a variety of analytic methods and criteria to aid in the diagnosis. Extraction formulas that has been presented are many analytic methods that depend on arch length discrepancy, dental prominence, and skeletal pattern of the each patients. Of these analysis, the most important diagnostic factor is patient's skeletal pattern. Because the behavior of the dentition is closely dependent upon the skeletal pattern of each patient, dentition must be arranged within that person's skeletal frame. El(Extraction Index) is composed of CF, interincisal angle, and lip position, CF is made of ODI and APDI that differentiate vertical and horizontal component of the skeletal pattern. So, EI not only represents patient's skeletal pattern, but also takes facial appearance into consideration, This study was undertaken to investigate EI and related cephalometric variables on the cephalogram of Korean adolescents which consisted of 153 persons with normal occlusion, harmonious skeleton and pleasing face. The following conclusions were obtained. 1. The mean value of the ODI is 73.5degrees, APDI 82.5degrees, CF 156.3degrees 2. The mean value of the interincisal angle is 123.6 degrees. 3. The mean distance of upper lip to E-line is 0.0mm, lower lip to E-line is 1.4mm. 4. The mean value of the EI is 153.8degrees.