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Nghiên cứu đặc điểm nhân trắc và sự tăng trưởng đầu mặt ở trẻ em người Kinh từ 7 đến 9 tuổi ttta

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Những kết luận mới của luận án: Đặc điểm nhân trắc đầu mặt ở trẻ 7 tuổi người Kinh Các kích thước khi đo trực tiếp ở nam lớn hơn nữ, các kích thước không khác biệt giữa ba loại khớp cắn. Dạng đầu chủ yếu là rất ngắn và ngắn (cvvđ: 513,33±12,53 mm; eu-eu: 138,90±5,20 mm; gl-op: 157,26±5,21 mm; po-n: 101,29±5,04 mm; po-pr: 112,83±8,74 mm). - Chiều rộng mặt, chiều rộng mũi, chiều rộng miệng, chiều rộng hàm dưới, chiều cao tầng mặt trên, giữa và dưới ở nam lớn hơn nữ, chiều rộng mũi loại I và II Angle lớn hơn loại III Angle, chiều cao tầng mặt giữa và dưới ở loại III lớn hơn loại I và II Angle (Zy-Zy: 120,97±4,76 mm; Al-Al: 30,92±2,56 mm; Ch-Ch: 38,06±2,80 mm; Go-Go: 90,06±4,76 mm; Tr-Gl: 52,14±3,86 mm; Gl-Sn: 54,71±4,14 mm; Sn-Me: 57,04±4,33 mm). - Các kích thước, chỉ số đo trên phim sọ nghiêng khác biệt không có ý nghĩa thống kê giữa nam và nữ trừ chiều dài nền sọ trước và sau ở nữ lớn hơn ở nam; hầu hết có sự khác biệt ý nghĩa thống kê giữa ba loại khớp cắn theo phân loại Angle trừ độ lệch nền sọ thì không có sự khác biệt (CC-N: 48,92±3,53 mm; Po-PtV: 37,11±2,35 mm; Ba-N/Xi-Pm: 60,55±5,09o; A/N-Pog: 1,37±3,03 mm; N-A/Fh: 90,39±3,06o; CC-Gn/Ba-N: 89,11±4,05o; N-Pog/Fh: 86,64±4,08o; Ls-E: 0,47±2,24mm; Li-E: 0,84±2,25mm; A1/B1: 122,65±12,08 o; R6HD/PtV: 11,35±3,23mm). Sự tăng trưởng đầu mặt từ 7-9 tuổi - Các kích thước khi đo trực tiếp và đo trên ảnh chuẩn hóa và phim sọ nghiêng tăng trưởng đều đặn theo tuổi từ 7-9 tuổi, nữ có xu hướng tăng trưởng sớm hơn nam, từ 8-9 tuổi có xu hướng tăng trưởng nhanh hơn từ 7-8 tuổi, mức gia tăng và tỷ lệ gia tăng giống nhau giữa hai giới trừ chiều rộng đầu và po-pr ở nữ lớn hơn ở nam. - Điểm giữa hố yên xương bướm (S): Di chuyển ra sau và lên trên, điểm khớp trán mũi (N): Di chuyển ra trước và lên trên theo trục Ba-N, điểm gai mũi trước (Ans): Di chuyển ra trước và xuống dưới, điểm cằm (Gn): Di chuyển xuống dưới và ra trước, điểm tâm cành đứng xương hàm dưới (Xi): Di chuyển ra sau và xuống dưới, điểm tâm cổ lồi cầu (Dc): Di chuyển ra sau và lên trên.

MINISTRY OF EDUCATION MINISTRY OF HEALTH AND TRAINING HANOI MEDICAL UNIVERSITY TRUONG DINH KHOI STUDY OF ANTHROPOMETRIC CHARACTERISTICS AND CRANIOFACIAL GROWTH IN KINH ETHNIC CHILDREN FROM TO YEARS OLD Major: Odonto-Stomatology Code: 9720501 SUMMARY OF DOCTORAL THESIS IN MEDICINE HANOI – 2022 THESIS COMPLETED AT HANOI MEDICAL UNIVERSITY Scientific instructor: Associate Professor Luong Ngoc Khue, PhD, MD Associate Professor Dao Thi Dung, PhD, MD Reviewer 1: Prof Lê Gia Vinh Reviewer 2: Assoc.Prof Le Thi Thu Ha Reviewer 3: PhD Nguyen Dinh Phuc Thesis will be defended to The Assessment Committee of Hanoi Medical University Time: Date: Thesis can be found at: National Library Hanoi Medical University Library A THESIS INTRODUCTION ABSTRACT The age from to years old is the first period of general growth of the whole body as well as of the dental arches and craniofacial structure, and the time when the incisors are fully developed and the jawbone develops for the teeth eruption of next stage During adolescence, the eruption of the first molars, the middle incisors and the growth in preparation stage for the next puberty 2, when the child is years old, it is necessary to take the child away the first orthodontic examination for early detection of maloclusion and maleruption At the age of 9, the lateral incisors, canines and premolars are ready for eruption, the time before the growth peak is of great importance in preventive orthodontic treatment and early intervention orthodontic treatment Therefore,The growth of the head from to years old plays an important role for the orthodontist to refer to in order to have appropriate treatment for each age group, and to predict the growth trend of the craniofacial structure In the world, there have been a number of head growth studies in children aged 7-9 years old, but mainly conducted on Caucasian people, so it is not completely suitable for Vietnamese people In Vietnam, there is no research on this issue Based on the growth assessment, clinicians can better understand the medical condition, predict the growth trend to decide on the treatment plan and can visualize the future face in three dimensions Therefore, we chose the topic "Studying of anthropometric characteristics and craniofacial growth in Kinh ethnic children from to years old" with the following two objectives: Determination of facial features and anthropometric indices in 7year-old Kinh ethnic children in Hanoi by direct measurement, on standardized images and on digital cephalometric radiographs Describe the craniofacial growth of the target group from to years old THE URGENCY OF THE SUBJECT Studying growth characteristics at the age from to years old has important significance in early diagnosis and orthodontic treatment in children In Vietnam, there is no research on growth at this age, especially the longitudinal research method that follows the research object for many years with a relatively large sample size The anthropometric characteristics of the head and the craniofacial growth provide craniofacial indexes that are the database for the orthodontists to refer to and predict the future facial morphology Besides, the indicators can also be used for other fields such as sculpture, painting, traffic safety or fashion and apparel The study is based on three methods of direct measurement, on standardized images and on cephalometric radiographs, which can analyze and compare both hard and soft tissues of the head and face PRACTICAL MEANING AND NEW CONTRIBUTION This is the first study that combines a cross-sectional descriptive study and a longitudinal study using all three measurement methods including direct measurement, standardized image measurement and lateral cephalometric measurement This is also a study with a large enough sample size to be representative of the Kinh people aged to years old in Vietnam Research on determining the characteristics and anthropometric indices of head and face in 7-year-old Kinh children in Hanoi by direct measurement, on standardized images and on digital cephalometric films, in order to give clinical practitioners of maxillofacial and plastic surgery and some other fields with a number of reference databases, used for analysis and comparison The study describes the craniofacial growth of the group from to years old Kinh people, builds a model of craniofacial growth to help orthodontists predict the morphology and growth trend, In this day and age, orthodontics is increasingly interested in, so this is a valuable resource for clinical practitioners THESIS STRUCTURE In addition to the Research Statement and Conclusion, the thesis consists of chapters: Chapter 1: An overview of research issues, 33 pages; Chapter 2: Research Object and Methods, 27 pages; Chapter 3: Research results, 38 pages; Chapter 4: Discussion, 43 pages Thesis also has 77 tables, diagram, 29 chart, 52 images, 136 references (including 28 in Vietnamese, 108 in English) B THESIS CONTENT Chapter THEORETICAL OVERVIEW 1.1 Some characteristics and craniofacial anthropometric indexes The growth of skull bones depends on two phenomena: - Surface bone accretion: There is bone accretion on the outside, increasing the volume of the skull, however, due to the increase in the volume of the brain inside, there is a phenomenon of bone resorption on the inside These two phenomena give the brain a three-dimensional increase in volume, but without a significant increase in skull mass - Osteogenesis at the joints: The phenomenon of bone formation from the connective tissue at the joints causes the bones to grow in lines perpendicular to the joints Joint lines are present in three dimensions in space, so cranial bone formation grows in all directions The growth of the base of the skull is dependent on: Bone replacement due to lobar growth of brain, growth at the cartilaginous lines and cortical repair The maxillary bone is formed from the membranous bone, there is no replacement of cartilage, so the maxillary bone grows by two processes: The phenomenon of accretion at the junction between the maxillary bone and the skull base of the skull, the accretion and dissolution of the surface of the maxillary bone 24,25,26 At birth, the mandible is short, the condyle is minimally developed, with only fibrous cartilage and connective tissue surrounding the mandible The growth of the mandibular bone is based on the growth of membranes and cartilage, chondrocytes develop in specialized areas including: convex, parietal and jaw angle Growth is based on cartilage growth and bone accretion - resorption on the bone surface 22,27 Soft tissue grows rapidly in thickness from birth to years of age, grows steadily during puberty and ends in growth in adulthood 1.2 Mechanism of growth in the craniofacial region The growth of craniofacial bones follows three mechanisms: growth at the joints, growth of cartilage and growth due to bone accretion/resorption The cranium grows at the joint lines formed from the narrowed fontanel area, the basal bone grows at the joints between the occipital, ethmoid, sphenoid bones, and the maxillary nasopharyngeal complex at the mid-maxillary joint lines, frontal bone, temporal bone and cheekbones Growth occurs in areas of chondrocytes containing chondrocytes, areas of cartilage that are not nourished by blood vessels by diffusion through the initial thin layers The process of bone accretion/resorption growth is based on two principles: the Vprinciple and the surface principle 22 1.3 Growth assessment methods Method of consecutive comparing values of research characteristics measured on living bodies, on craniofacial radiographs and standardized images: Based on measured data of length, distance and angle, it is possible to evaluate growth, this comparison method is widely used because of its high quantification, ease of comparison between subjects, assessment of the difference in individual or on the same sample as well as between samples at same time or different times Consecutive superposition method: The superimposed method aims to determine the position and growth direction of the research characteristics Cephalometric radiographs and photos of each object are superimposed at different times according to planes, lines, and reference points 1.4 Methods to study craniofacial growth The method of using anthropometric instruments to directly measure the indicators on the face, the classic Martin anthropometric instrument kit includes: length ruler, distance measure, angle ruler, measuring tape for determining circumference Standard facial landmarks according to Farkas et al (1992) The use of standardized images supports the method of measuring on remote film quickly, safely, at low cost and convenient to store and exchange information; identify landmarks that are not visible on the film taken from a distance such as the wings of the nose, corners of the eyes, the edges of two lips; simple operation, saving time and manpower when measuring, can be analyzed by digitizing software on computer 65,66 The normalization of images in Claman's (1990) 68 study makes the normalized image more valuable and reliable in the study Ricketts' research emphasizes children's growth and direction of growth Ricketts analysis allows us to understand the morphology of the craniofacial and determine the type of face, the relationship between the craniofacial components Study on the ability to predict growth on cephalometric radiographs 1.5 Some studies in the world and Vietnam 1.5.1 Some studies in the world: There are a number of studies on the growth of the head and face area based on measurements on the living body, measured on standardized images and on craniofacial radiographs, from which to find out the increasing level, growth trends and factors affecting growth at different ages, including a study from to years old Research by Farkas L G (1992) 7, (2005) 8, K Albertsson (2002) 9, Cleidy.A (2011) 10, Bishara S.E (1995) 11, Thilander B (2005) 12, (2009) 13 1.5.2 Some studies in Vietnam: There have been a number of studies on craniofacial growth measured directly on living bodies, indirectly measured on standardized images and measured on craniofacial films, research by Ngo Thi Quynh Lan (2000) 14, Le Duc Lanh (2007) 15, Dong Khac Tham (2009) 16, Vo Truong Nhu Ngoc (2010) 17, Le Vo Yen Nhi (2011) 18, Truong Hoang Le Thuy (2012) 19, Le Nguyen Lam (2014) 20 Thus, based on scientific reports of domestic and international authors, there have been a number of studies on anthropometric characteristics and head growth, however, they are limited to a direct measurement method, measured on digital normalized images or on craniofacial radiographs; growth studies from to years old are still few, sample size is small, most of the studies are on Caucasian race, so the application of research results to Vietnamese people is not completely appropriate More studies help clinical practitioners, orthodontists have a basis for more accurate diagnosis and treatment planning Chapter SUBJECTS AND RESEARCH METHODS 2.1 Location and research time 2.1.1 Research location: Hanoi city 2.1.2 Research period: From April 2017 to October 2020 2.2 Research subjects The study subjects at the beginning of the study were 7-year-old children (born from January 2012 to July 2012) at Lien Ninh Primary School, Lien Ninh Commune, Thanh Tri district, Hanoi city two years in a row a Selection criteria: Subjects were Kinh ethnic people with Kinh ethnic parents and grandparents, normal health, at the beginning of the study, the average age was years ± months according to the date of birth in the entry records of research subjects There is a mixed set of teeth with the first molars are fully grown, touching on both bimaxillary, and have the same occlusal relationship of the first molars on both sides There are four fully grown two-molar incisors on the jaw No orthodontic treatment before and during the study period There were no congenital malformations of cleft palate or jaw deformity No disease affecting the development of the body and head - face area There was no serious infection or trauma to the maxillofacial region Children and their relatives (parents or guardians) agree to participate b Exclusion criteria: Study subjects had dissimilar first molars on both sides Having undergone orthodontic treatment or congenital malformations cleft palate, jaw bone deformity Having bad habits affecting facial growth such as lip-sucking, thumb-sucking, mouth-breathing, tongue thrusting Children lose baby teeth early or suffer from infectious diseases, serious trauma to the maxillofacial region Children and their relatives (parents or guardians) did not consent to participate in the study 2.3 Research design: The study was designed according to the descriptive cross-sectional and longitudinal research methods 2.4 Select a research sample 2.4.1 Sample size The sample size was determined according to the sample size calculation formula of the descriptive study to determine the mean 125: In which: n: Minimum sample size studied (for each sex), Z1 / : Reliability coefficient, with a confidence level of 95%, the confidence coefficient is 1,96; SD: Standard deviation of research index, X : Mean value of research index ε: Relative difference between sample parameter and population, choose ε = 0,015 Based on the research of Truong Hoang Le Thuy, taking the average value of face width at years old 19: X ±SD: 120,3±5,2 (mm), the minimum sample size for each sex was calculated as n = 31,90 Thus, each gender has at least 32 research subjects In fact, we conducted a study on 206 subjects (104 men, 102 women) 2.4.2 How to choose the sample We conduct a convenience sample study purposefully to meet the research sampling criteria 125 2.4.3 Sample selection process Flowchart of the research process 2.5 Steps for conducting research Step 1: Select Lien Ninh Primary School, Lien Ninh Commune, Thanh Tri District, Hanoi, select research subjects by date of birth in the school's admission records, survey the ethnicity of parents and grandparents, a total of 489 children of Kinh ethnicity, age years ± months (according to date/month/year of birth) Every 12 months, we measure and re-collect the research data, for consecutive years Step 2: Subjects were taken to direct measurement, on standardized straight and inclined images, and cephalometric films at the Institute of OdontoStomatology Training, building A7, No 01 Ton That Tung, Hanoi, affiliated to the Hanoi Medical University), from April 18 to April 25, conducted three times in two consecutive years 2.6 Data Collection Tools 2.7 Processing and analyzing data The collected data was entered into the computer, then processed by Epiinfo 6.0 program, SPSS 23.0 statistical software and statistical algorithm 2.8 Errors and how to control errors 2.9 Ethical issues in research The study was approved by the Council of Ethics in Biomedical Research at Hanoi Medical University Chapter RESEARCH RESULT 3.1 General characteristics of the research subjects: Our study sample included 206 children, who started the study at the age of years and were followed up to years of age, including 104 boys and 102 girls Male accounted for 50,49% and female accounted for 49,51% (Type I Angle: 36 male, 37 female; Type II Angle: 35 male, 33 female; Type III Angle: 33 male, 32 female) 3.2 Craniofacial anthropometric indices in 7-year-old Kinh children 3.2.1 Characteristics by direct anthropometric measurement method Table 3.1 Head-to-face anthropometric size in 7-year-old Kinh children between three occlusal groups by direct measurement (mm) (n=206) Dimensions Classification of occlusion according to Angle P Class I Class II Class III General Male 516,28±14,06 515,20±12,29 516,24±12,19 515,90±12,78 PI-II; PI-III; PII-III >0,05** Female 510,76±10,51 510,52±11,04 510,81±13,99 510,70±11,75 PI-II; PI-III; PII-III >0,05** cvvđ P1 0,0110 0,0037 0,0099 0,0027 General 513,48±12,61 512,93±11,85 513,57±13,29 513,33±12,53 PI-II; PI-III; PII-III >0,05** Male 140,75±5,30 139,60±5,15 140,15±5,12 140,17±5,16 PI-II; PI-III; PII-III >0,05** 137,78±4,92 137,00±5,17 138,03±4,78 137,61±4,93 PI-II; PI-III; PII-III >0,05** eu-eu Female P1 0,0156 0,0417 0,0195 0,0003 General 139,25±5,29 138,34±5,28 139,11±5,03 138,90±5,20 PI-II; PI-III; PII-III >0,05** Male 158,53±6,32 158,11±4,48 158,52±5,12 158,38±5,32 PI-II; PI-III; PII-III >0,05** 156,62±4,81 155,88±5,04 155,75±4,81 156,11±4,85 PI-II; PI-III; PII-III >0,05** gl-op Female P1 0,0206 0,0372 0,0284 0,0016 General 157,56±5,65 157,03±4,86 157,15±5,12 157,26±5,21 PI-II; PI-III; PII-III >0,05** Male 102,33±4,76 102,29±5,01 102,39±5,20 102,34±4,94 PI-II; PI-III; PII-III >0,05** 100,11±4,67 100,45±5,20 100,13±5,12 100,23±4,94 PI-II; PI-III; PII-III >0,05** po-n Female P1 0,0577 0,1440 0,0813 0,0725 General 101,21±4,82 101,40±5,15 101,28±5,25 101,29±5,04 PI-II; PI-III; PII-III >0,05** Male 112,14±5,22 122,83±5,97 106,88±5,38 114,07±8,60 PI-II; PI-III; PII-III < 0,017* 109,73±5,06 120,85±6,22 104,13±5,14 111,57±8,74 PI-II; PI-III; PII-III < 0,017* po-pr Female P1 0,0590 0,1848 0,0589 0,0699 General 110,92±5,24 121,87±6,13 105,52±5,40 112,83±8,74 PI-II; PI-III; PII-III < 0,017* P1 (Sample T-test), P (*: One way ANOVA with Bonferoni test, **: Kruskal Wallis test with Mann- Whitney test) Head circumference (cvvđ), head width (eu-eu), head length (gl-op) statistically significant differences between the sexes in each type of occlusion according to Angle classification (p) 0,05, there is no change with age in type I Angle The R6HD to PtV distance and the lower mandibular body length were not statistically significant between the sexes when compared in the same age group and occlusal type according to Angle's classification Table 3.12: Increment level and rate of increase in facial axial angle by measurement on cephalometric radiographs from 7-9 years of age (n=206) 14 Ages Class II Male Increment level (mm) Female P1 General Male Incresing rate (%) Female P1 General Class III Male Increment level (mm) Female P1 General Male Incresing rate (%) Female P1 General 7-8 -0,48±0,34 -0,52±0,36 0,8204** -0,50±0,35 -0,56±0,37 -0,61±0,42 0,8300** -0,53±0,39 0,41±0,29 0,45±0,35 0,7879** 0,22±0,52 0,44±0,33 0,49±0,36 0,7980** 0,47±0,34 8-9 -0,52±0,36 -0,62±0,39 0,3542** -0,57±0,37 -0,61±0,41 -0,73±0,47 0,3354** -0,67±0,44 0,53±0,37 0,57±0,44 0,6529** 0,29±1,06 0,57±0,36 0,62±0,44 0,9268** 0,60±0,40 p 7-9 -1,00±0,48 -1,14±0,56 0,3638** -1,07±0,52 -1,17±0,54 -1,36±0,61 0,3671** -1,21±0,57 0,94±0,45 1,02±0,54 0,6319** 0,50±1,16 1,05±0,48 1,11±0,57 0,6180** 1,08±0,52 0,7933** 0,2877** 0,3134** 0,7807** 0,2877** 0,3075** 0,5981** 0,7084** 0,5134** 0,5735** 0,7364** 0,4988** P1, P (*: sample T-test, **: Mann – Whitney test) Increment level and rate of increase in biliary protrusion, the difference was not statistically significant between the sexes in each growth age interval, the growth from 8-9 years old was greater than that from 7-8 years old, but the difference has no statistical significance Table 3.13: Increment level in lower lip protrusion by cephalometric measurement from 7-9 years old (n=206) Class I Increment level (mm) Male Female P1 General Loại II Increment level (mm) Male Female P1 General Class II Increment level (mm) Male Female P1 General 7-8 -0,20±0,78 -0,23±0,86 0,5144* -0,22±0,82 0,23±0,15 0,26±0,20 0,6256* 0,24±0,17 -0,24±0,67 -0,27±0,73 0,5052* -0,25±0,70 Ages 8-9 -0,24±0,82 -0,26±0,87 0,4944** -0,25±0,85 0,24±0,10 0,28±0,23 0,4197** 0,26±0,18 -0,26±0,71 -0,30±0,79 0,3958** -0,28±0,75 p 7-9 -0,44±0,97 -0,49±1,03 0,4772** -0,47±0,99 0,47±0,17 0,54±0,28 0,3141** 0,50±0,23 -0,50±0,89 -0,57±0,95 0,2285** -0,53±0,92 0,3878** 0,4001** 0,3556** 0,9003** 0,8718** 0,7992** 0,7335** 0,6603** 0,5703** P1 (*: sample T-test, **: Mann – Whitney test) S-point moves up and back, the difference in the amplitude of movement between the sexes in the same type of occlusion and between the three groups of occlusal groups is not statistically significant N-point moves upward and forward, the difference in the amplitude of movement between the sexes in the same type of occlusion and between the three groups of occlusion is not 15 statistically significant Ans point moves downwards and forwards, the amplitude of movement in type II Angle is larger than that of type I and type III Angle is statistically significant, however, the difference between the sexes in the same occlusal group has no statistical significance (with 0>0,05) Table 3.14: Change of the growth coordinates of the S, N and Ans points from 7-9 years old (mm) (n=206) Dimensions S79x Male Female P1 General S79y Male Female P1 General N79x Male Female P1 General N79y Male Female P1 General Ans79x Male Female P1 General Ans79y Male Female P1 General Classification of occlusion according to Angle Class I Class II Class III General -1,22±0,64 -1,25±0,58 -1,25±0,60 -1,23±0,62 -1,29±0,66 -1,33±0,62 -1,33±0,63 -1,31±0,65 0,5401** 0,4074** 0,4074** 0,4907** -1,26±0,65 -1,27±0,60 -1,27±0,61 -1,27±0,63 1,26±0,50 1,27±0,48 1,27±0,47 1,23±0,48 1,35±0,53 1,37±0,51 1,37±0,50 1,35±0,50 0,4972** 0,3082** 0,3082** 0,6179** 1,30±0,52 1,29±0,50 1,29±0,48 1,29±0,49 1,49±0,77 1,55±0,74 1,55±0,79 1,45±0,76 1,67±0,85 1,71±0,77 1,71±0,82 1,61±0,83 0,4596** 0,6586** 0,6586** 0,3686** 1,58±0,81 1,53±0,75 1,53±0,80 1,53±0,78 1,26±0,69 1,34±0,64 1,34±0,65 1,22±0,68 1,52±0,66 1,60±0,68 1,60±0,64 1,43±0,67 0,1075* 0,1056* 0,1056* 0,1532* 1,39±0,68 1,33±0,66 1,33±0,64 1,33±0,67 1,27±0,75 1,21±0,83 1,43±0,68 1,79±0,64 1,33±0,77 1,27±0,78 1,49±0,75 1,87±0,72 0,2083** 0,1929** 0,1929** 0,2617** 1,30±0,77 1,24±0,72 1,46±0,72 1,83±0,72 -1,25±0,62 -1,22±0,67 -1,45±0,65 -1,87±0,60 -1,32±0,66 -1,25±0,63 -1,49±0,64 -1,91±0,62 0,2704** 0,1691** 0,3691** 0,1022** -1,29±0,64 -1,23±0,65 -1,47±0,64 -1,89±0,61 P PI-II; PI-III; PII-III >0,017 PI-II; PI-III; PII-III >0,017 PI-II; PI-III; PII-III >0,017 PI-II; PI-III; PII-III >0,017 PI-II; PI-III; PII-III >0,017 PI-II; PI-III; PII-III >0,017 PI-II; PI-III; PII-III >0,017 PI-II; PI-III; PII-III >0,017 PI-II; PI-III; PII-III >0,017 PI-II; PI-III; PII-III >0,017 PI-II; PI-III; PII-III >0,017 PI-II; PI-III; PII-III >0,017 PI-II; PII-III 0,017 PI-II; PII-III 0,017 PI-II; PII-III 0,017 PI-II; PII-III 0,017 PI-II; PII-III 0,017 PI-II; PII-III 0,017 P1 (*: Sample T-test, **: Mann- Whitney test); P (One way ANOVA kết hợp Bonferoni test) Point Gn moves down and forward, point Xi moves down and back, point Dc moves up and back The difference in movement amplitude between the sexes in each type of occlusion was not statistically significant When comparing between the three groups of occlusion, the Gn point has a larger forward displacement in Type III Angles than in Type I and II Angles, a larger amplitude of downward movement in Type II Angles than in Type I and III Angles; point Xi has a larger amplitude of downward and backward movement in type II angle than in type I and III Angle; Dc point has a larger margin of backward movement in type III Angle than in type I and II Angle, however, the amplitude of upward movement in type II is significantly larger than that of type I and III Angle (p

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