Đang tải... (xem toàn văn)
Tóm tắt những đóng góp mới của luận án: Tên đề tài là “Nghiên cứu đặc điểm lâm sàng, x-quang và đánh giá hiệu quả điều trị hẹp chiều ngang xương hàm trên bằng hàm nong nhanh có kết hợp minivis” hoàn toàn phù hợp với chuyên ngành răng hàm mặt, thuộc mã chuyên ngành răng hàm mặt. Đề tài không trùng lặp với các luận án, luận văn và các công trình nghiên cứu khoa học đã công bố. Ý nghĩa khoa học thực tiễn của đề tài: - Hẹp chiều ngang XHT là một loại bệnh thường gặp, chiếm tỷ lệ không nhỏ, gây ảnh hưởng đến thẩm mỹ và đặc biệt là chức năng ăn nhai. - Các phương pháp điều trị hẹp chiều ngang XHT đã biết chỉ có tác dụng chủ yếu khi BN chưa đến tuổi trưởng thành nhờ vào khí cụ ốc nong xương. Như vậy, một số lượng lớn bệnh nhân sẽ không được tiếp nhận điều trị khi đến khám muộn. Vì vậy việc ra đời khí cụ ốc nong xương kết hợp với minivis là điều cần thiết để điều trị cho nhóm bệnh nhân ở tuổi trưởng thành. Vì vậy đề tài nghiên cứu về hiệu quả mở rộng xương hàm trên của khí cụ MARPE mang ý nghĩa khoa học, có tính thời sự và thực tiễn cao. - Nghiên cứu sử dụng phương pháp chẩn đoán hẹp chiều ngang xương hàm trên dựa theo tiêu chuẩn trên phim CBCT của Penn, khác với tiêu chuẩn dựa trên lâm sàng, nhiều khi chưa được chính xác. Những kết quả mới đạt được: - Kết quả nghiên cứu cho thấy khí cụ nong xương MSE có hiệu quả mở rộng xương hàm trên đối với trẻ ngừng tăng trưởng và người trưởng thành với minh chứng là có sự tách rõ rệt của khớp khẩu cái. Trong đó sự mở rộng của xương hàm trên chiếm tỷ lệ khá cao, sự nghiêng của răng và xương ổ răng chỉ chiếm một phần nhỏ. - Sự mở rộng của khớp khẩu cái là gần như đạt được sự song song ở cả phía trước và phía sau, phía trên và phía dưới, khác với một số nghiên cứu cho rằng sự mở khớp là theo hình kim tự tháp: mở nhiều ở phía dưới, ở phía trước và mở ít ở phía trên, phía sau. - Kết quả nghiên cứu cũng cho thấy hơn 94% bệnh nhât đạt kết quả điều trị tốt ở cả giai đoạn sau 6 tháng duy trì, cho thấy sự ổn định ban đầu của khí cụ MSE là có thể chấp nhận được.
MINISTRY OF EDUCATION AND TRAINING MINISTRY OF DEFENCE 108 INSTITUTE OF CLINICAL MEDICAL AND PHARMACEUTICAL SCIENCES - PHAM THI HONG THUY A STUDY ON MAXILLARY TRANSVERSE DEFICIENCY: CLINICAL CHARACTERISTICS, X-RAY AND TREATMENT EFFECTIVENESS EVALUATION USING MINIVIS ASSISTED RAPID PALATAL EXPANDER Speciality: Odonto stomatology Code: 9720501 ABSTRACT OF MEDICAL PHD THESIS Hanoi – 2022 THE THESIS WAS DONE IN: 108 INSTITUTE OF CLINICAL MEDICAL AND PHARMACEUTICAL SCIENCES Supervisor: Assoc Prof Ph.D TRINH THI THAI HA Ph.D PHAM THI THU HANG Reviewer 1: Reviewer 2: Reviewer 3: This thesis will be presented at Institute Council at: 108 Institute of Clinical Medical and Pharmaceutical Sciences Day Month Year The thesis can be found at: National Library of Vietnam Library of 108 Institute of Clinical Medical and Pharmaceutical Sciences Central Institute for Medical Science Infomation and Tecnology INTRODUCTION The transverse deficiency of maxilla is one of the most common diseases in orthodontics, which accounted for approximately 10% in all cases Over 180 years ago, several researchers presented the traditional maxillary expansion in order to re-establish the relevance between the transverse dimension of maxilla and mandible before reaching the growth peak Adult patients with transverse maxillary deficiency are prescribed with surgical treatment However, this solution causes high payment and long-term hospitalization Lee et al from Korea, Moon et al from America have recently investigated the palatal expansion appliance assisted minivis which can optimize pressure distribution on maxilla as well as minimize it on upper teeth and alveolar Thus, maxillary expansion still owns a percentage to succeed for adult patients Numerous researches in the world have assessed the results of using minivis assisted rapid palatal expansion in maxillary transverse deficiency treatment However, in the context of Vietnam, little to no research exists regarding this matter Therefore, we conducted the study “A study on maxillary transverse deficiency: clinical characteristics, X-ray and treatment effectiveness evaluation, using minivis assisted rapid palatal expansion” with two objectives: Comment on clinical characteristics, X-ray in maxillary transverse deficiency patients Evaluate treatment effectiveness of maxillary transverse deficiency using minivis assisted rapid palatal expansion Chapter OVERVIEW Epidemiological characteristics of the Maxillary transverse deficiency (MTD) Maxillary transverse deficiency is a fairly common disease among orthodontic patients, accounting for about 9,4% of the population Clinical and radiographic characteristics of MTD 2.1 Clinical characteristics -The straight-face: Flattened mid-face, or long lower face, lips are not closed can be seen, depending on other reasons combined The ratio of mouth corridor when smiling (dark space): great The sideways-face: The upper lip can be seen moving back or protruding The characteristics of occlusion: the patient’s occlusion can be the class I, II or III, according to Angle Posterior cross-bite in a few teeth or all, on one or both sides, or cross-bite in both front and sides with crowding of teeth May be accompanied by the deep-bite or open bite Other features: misaligned teeth, impacted teeth The width of the Dental arch which is measured in plaster samples The horizontal dimension of the dental arch in patients with Maxillary transverse deficiency is usually smaller than normal, with the Shape of the dental arch being V-shape or narrow oblong shape The Radiographic Characteristics: According to Rickett, the width of Maxillary (J-J) and Mandibular in patients is compared to normal values Besides, Posterior-Anterior X-ray film (PA X-ray) also evaluates the correlation between the dental arch and the width of the face through the IZARD index: (Za-Za) = x (A6-A6) 1.3 Diagnosis of Maxillary transverse deficiency May be based on clinical and radiographs Characteristics In 2010, Ryan K Tamburrino, introduced the Penn CBCT diagnostic criteria Accordingly, the Maxillary bone’s width was determined as the distance between two points on the outer surface of the Cortical bone, the intersection between the Alveolar bone and the Zygomatic process of the Maxillary Mandibular bone’s width was determined as the distance between two points on the outer surface of the cortical bone, corresponding to the Cleft point of the mandibular first molar root The difference between the width of the Maxillary and Mandibular bone is mm 1.4 Treatment of Maxillary transverse deficiency 1.4.1 The treatment methods of Maxillary transverse deficiency 1.4.1.1 Rapid maxillary expander (RME) Effect of RME on vicinity structures: Maxillary skeletal: moving side to side, forward and down Maxillary Alveolar bone: tilting towards the cheek, there is a gap between the two incisors Maxillary posterior teeth: tilting towards the cheek Palatal mucosa and periodontal tissue: can be inflamed or ulcerated Mandibular skeletal: can be rotated downwards Mandibular teeth: slight increase in transverse size Effects on the airway system: there is an increase in airway width Smiles show more teeth Time of treatment: traditional rapid expansion should be treated before the Peak of Puberty Indication of RME: transverse dimension deficiency ≥ mm Screw activation: multiple procedures are given depending on the authors Instrument and band design: Hyrax rapid expander, Hass quick expander 1.4.1.2 Slow maxillary expander (SME) SME procedures produce less tissue resistance around the circummaxillary structures and, therefore, improve bone formation in the intermaxillary suture, which theoretically should eliminate or reduce the limitations of RME Some SPE tools: W-Arch, Quadhelix Tool 1.4.1.3 Surgically assisted rapid palatal expansion (SARPE) Enlarge the maxillary bone when the width lacking is more than mm Several surgical procedures have been proposed to assist with palatal dissection, or Combine the median joint separation surgery and Le Fort I osteotomy for the treatment of Maxillary transverse deficiency in an adult patient 1.4.1.4 minivis assisted rapid palatal expander (MARPE) Moon et al developed the maxillary expander with minivis (MSE) attached to rapid expansion screws on either side of the midline, parallel to the midline of the palatal joint The placement of the minivis in the MSE design is more posterior, level with the maxillary first molar 1.4.2 Evaluation of the results of MTD Treatment Comparing MARPE with RPE: MARPE expands bones more, more parallel Comparing MARPE with SARPE: MARPE expands bones equally, more parallel, less affected periodontal tissue Recent studies by Choi S.H., Clement E.A., Li Q.T., Lim H.M., Ngan P.N., Park J.J., Shin H.H., Na Li show that the success rate of this method is quite high, 80,65% - 100% Chapter MATERIALS AND METHODS 2.1 Subject Patients with maxillary transverse deficiency indicated for minivis assisted palatal expansion at Odonto-Stomatology Department of Haiphong University of Medicine Hospital 2.1.1 Inclusion criteria: - Patients diagnosed with maxillary transverse deficiency according to University of Pennsylvania CBCT analysis with cervical vertebrae maturation (assessed on lateral cephalometric radiographs) from stage onwards (Baccetti and al.) and are subjected to miniscrews assisted rapid palatal expansion - CBCTs that are clear with no imposition of soft tissue structures and skeletal structures on one another -The upper first molar is intact - Patients voluntarily participate in research, cooperate during the treatment process 2.1.2 Exclusion criteria - Patients with craniofacial congenital abnormalities - Patients with exostosis, palatal deformity 2.2 Time and location of study 2.2.1 Location of study All the patients were examined, diagnosed, and receive treatment at the Department of Odonto-Stomatology of HaiPhong Medical University Hospital 2.2.2 Time of study The study lasted from December 2018 to May 2022 2.3 Research method 2.3.1 Research design: This is an uncontrolled clinical intervention study Evaluating the effectiveness according to the before – after model 2.3.2 Sample size The sample size formula: This is the formula for a single-sample study, a one-sample 𝛼 +𝑍1−𝛽 1− 𝑍 test 𝑛= 𝐸𝑆 With a difference of 𝐸𝑆 = In which: - n is the minimum sample size needed - μ1 and σ are the mean and standard deviation according to the study of Cantarella Daniele μ1 =4.75 σ=2.59 - μ2 is the desired palatal suture extension value achieved for this study to be clinically significantl μ2 = 3.5 - Z1-α/2 is the value from the standard distribution, calculated based on the probability of error of type With α=0.05, Z1-α/2 =1.96 - Z1-β is the value from the normal distribution, calculated based on the statistical power With β=80%, Z1-β=0.842 After putting the data into the formula, n=34 In fact, in the study, 36 patients recieved treatment * Sample selection method: Patients who met the selection criteria were selected until the number of study subject was sufficient 2.4 Study procedure 2.4.1 Data collection method * Interview: Patients information is taken, including name, age, gender * Clincal examination - Facial examination: Define face shape (long, short, medium), The face is balanced or deviated from the midline, Smile: narrow, medium, wide - Intra-oral examination: Occlusion examination: in the maximal intercuspation position Diagnosis of occlusion according to Angle classification: Type I, II, III Examination to confirm cross bite: anterior crossbite, posterior crossbite (one side or two sides) Check for supernumerary teeth, missing teeth, and hidden teeth in positions on the arch * Analysis on dental cast: The patient's impression was sampled at three time points before treatment (T0), after stopping the expansion (T1) and after months of maintenance (T2): Determine the shape of the dental arch Determine the degree of crowding of the upper and lower dental arches Measure the width of the gap between the two incisors at the time of stopping the expansion Measure the width of the dental arch at the positions of canines, premolars and molars at T0, T1 and T2 * Analysis on cephalometric and CTCB film (T0, T1, T2) On Cephalometric Vertical rating parameters: Face axis angle, height of the lower face (ANS-Xi-PM), mandibular plane angle (MPA), palatal plane angle (PPA), Y axis angle, angle between the palatal plane and the mandibular plane Anterioposterior rating parameters: Depth of the maxillary bone (FH-NA), protrusion of the face (A-NPo), SNA angle (SN-NA), SNB angle (SN-NB), ANB angle (NA-NB) Parameters on CTCB films: Reference planes on CBCT: The maxillary Sagittal Plane (MSP): plane passing through the anterior nasal spine (ANS), posterior nasal spine (PNS) and Nasion (N) The axial palatal plane (APP) is perpendicular to the maxillary sagittal plane (MSP) and passes through the anterior nasal spine (ANS) and the posterior nasal spine (PNS) The V-coronal plane (VCP) is perpendicular to the maxillary sagittal plane (MSP) and to the axial palatal plane (APP) and passes through the most posterior point of the vomer (V point) Reference sections: The axial palatal section (APP), the lower nasal section (LNS), the upper nasal section (UNS), coronal and transverse 11 2.4 Error control methods Choosing patients fulfilling the requirements and achieving an agreement on the data collection methods With the measurement on radiographs, to reduce error, each index would be measured times, and each time would be at least week apart by the same person.The value taken is the avarage of measured values Clinical evaluation criteria are clearly defined 2.5 Statistics collection, entry and processing - The collected data will be entered, analyzed, and processed on the computer by medical statistics method according to the program SPSS 20.0 12 Chapter RESULTS 3.1.Clinical and radiographic characteristics of patients with transverse maxillary deficiency 3.1.1.Clinical characteristics - Number of patients: female: 24, male: 12, average age: 20,14 - Class III (Angle): accounted for a higher rate - Distribution of study subjects by crossbite group: bilateral posterior crossbite: 21 (58,33%), unilateral posterior crossbite: (13,89%), non-crossbite: 10 (27,78%) - Width of maxillary arch at canine position: 34,13±3,02 mm, first premolar: 41,30±2,94 mm, first molar: 52,26±3,02 mm Table 3.3 Frequency of some clinical characteristics n % Crowded tooth 16 45,71 Impacted canine 16,67 Narrow smile 33 91,67 Narrow maxillary arch:V shape 17 47,22 Comment: Among the clinical signs of patients with transverse maxillary deficiency, narrow smile accounted for the highest percentage, the second is crowded tooth and narrow arch 3.1.2.Radiographic characteristics - Cephalometric: Some indicators on cephalometric before treatment: there was not much deviation from the average results given 13 - CBCT: maxillary width is: 61.55 mm, 1.77 mm larger than mandibular with 3.2 Evaluate the effectiveness of treatment of transverse maxillary decifiency with minivis assisted rapid palatal expander 3.1.1 Cinical changes after treatment - Expansion level of screws: 8,67 mm, average treatment time: 32,52 days, distance between two incisors: 3,50 ± 2,16 mm - Width of the dental arch increased markedly at all positions, canine: 3,77 ± 2,91 mm, first molar: 4,27 ± 3,1 mm, molar: 5,79 ± 3,27 mm After months of retention (T2), the arch width at the above positions tended to decrease compared to the time T1, but these values are still much larger than the values at the initial time (T0) 3.1.2 Radiographic changes after treatment Table 3.18 palatal suture, alveolar, dental changes posttreatment (coronal section across the first molar) Parameter (mm) Inter-molar Width n Mean ± SD Min Max T0 36 40,53 ± 3,36 33,1 47,8 T1 36 46,47 ± 3,78 39,2 55,5 36 46,39 ± 3,60 39,7 55,1 36 4,04 ± 1,20 2,5 7,4 0.00 36 4,07 ± 1,20 2,5 7,4 0.00 T0 36 61,55 ± 3,19 57,1 68,1 T1 36 66,60 ± 3,09 61,3 75,5 T2 36 66,75 ± 3,13 61,5 76,0 T0 36 30,96 ± 2,33 26,8 36,0 T2 Midpalatal suture split (palatal site) Midpalatal suture split (nasal site) Maxillary Width Palatal p 0,00 0,00 0,00 14 Maxillary T1 36 35,56 ± 2,35 31,6 40,7 Width T2 36 35,69 ± 2,41 31,7 41,2 Comment: At T1: Total expansion achieved from MSE treatment was 5,94 mm, defined as the change in the intermolar width The amount of skeletal expansion that accounted for total expansion was 67,34 %, due to midpalatal suture split (4,0 ± 1,22 mm) This meant the remaining 32,66 % that contributed to total expansion was from dentoalveolar expansion At T2: these values changed slightly Table 3.28 Changes in nasal cavity n=36 Nasal base width Nasal cavity width Mean ± SD Max Min T0 29,63 ± 3,10 38 23 T1 33,62 ± 3,21 39,5 26,8 T2 32,92 ± 3,43 39.6 25.5 T0 26.88 ± 1,85 31,6 23,5 T1 28,90 ± 1,80 34 25,5 T2 28,69 ± 1,91 33,9 25,1 p 0,000 0,000 Comment: nasal base width increased by 3,99 mm after expansion and decreased by 0,7 mm after months of retention Nasal cavity width increased by 2,02 mm after expasion and decreased by 0,21 mm after months 3.1.1.1 Dental and alveolar bone changes Table 3.29 Alveolar bone bending angle n=36 Right Left Mean ± SD Max Min T0 107,22 ± 8,22 130,4 87,9 T1 111,29 ± 7,40 128,2 99,9 T2 111,05 ± 7,33 127,6 100 T0 108,36 ± 7,09 125,5 95 p 0,000 15 T1 112,78 ± 6,80 128,0 99,9 T2 113,53 ± 7,16 127,5 99,5 0,000 Comment: Right alveolar bone bending angle increased 4,07o after expansion and decreased by 0,24o after months Left alveolar bone bending angle increased also by 4,42o, and after months, this value increased slighly by 0,75o Table 3.30 Dental tipping angle (first molar) n=36 Right Left Mean ± SD Max Min T0 95,44 ± 4,34 101,4 86,7 T1 102,62 ± 6,41 113,7 91,5 T2 100,12 ± 6,68 111,5 89,1 T0 95,31 ± 6,91 109,7 80,2 T1 103,82 ± 7,96 119,3 86,9 T2 98,69 ± 8,01 113,7 81,5 p 0,000 0,000 Comment: Dental tipping angle at first upper molar in right site increased by 7,18o at T1, and decreased by 2,5o at T2 Dental tipping angle at first upper molar in left site increased by 8,51o at T1, and decreased by 5,13o at T2 - Alveolar bone thickness changes at first maxillaty molar: Buccal bone thickness at first maxillaty molar decreased after treatment and slightly increased again after retention time Palatal bone thickness at first maxillaty molar showed a rise after treatment and and retention time - Changes in pterygopalatine sutures (axial view): The average width of openings between pterygoid plates was 1,24 and 1,15 mm for the right and left suture, respectively 16 3.1.2 Cephalometric changes Table 3.39 Cephalometric changes after expansion time and retention time T0 T1 T2 p Vertical Anteroposterior Mean SD Mean SD Mean SD Face axis 88,86 2,75 88,88 3,27 88,85 3,27 0,00 LFH 44,43 2,91 44,54 3,65 44,73 3,38 0,00 MPA 23,05 5,25 22,79 5,99 23,27 5,88 0,00 PPA 0,15 3,43 0,65 2,11 0,68 1,93 0.05 Góc Y 66,04 2,97 65,93 3,21 66,28 2,99 0,00 PP-MP 22,48 5,87 22,24 6,22 22,19 5,88 0,00 FH-NA 88,22 3,27 88,20 2,94 88,42 2,89 0,00 A-NPo 1,57 3,14 1,83 3,45 2,10 3,12 0,00 SNA 84,15 3,88 84,61 3,90 83,86 3,28 0,00 SNB 82,44 4,32 82,50 3,83 82,56 4,26 0,00 ANB 1,62 2,73 2,04 2,83 1,88 2,68 0,00 Comment: The vertical and anteroposterior parameters at three time T0, T1, T2 had a difference, however, this amount of diference was small 3.1.3 Treament results - Between 36 studied patients, patients had moderate treatment results, 34 patients had good treatment results, both at the time of stopping the expansion and after months of maintenance 17 Chapter DISCUSSION 4.1 Clinical characteristics and X-ray According to the Angle’s classification, the outcomes indicated that class II and III account for a significant part (Table 3.1) The transverse deficiency of maxilla exists in all three classes, however, the patients with the symptoms of maxillary transversal associated with anteroposterior deficiency were recorded in most cases Bushra et al concluded that the percentage of class I, II, III were 40,8%, 26,5% and 32,6%, respectively Crossbite is one of those symptoms of the maxillary transverse deficiency; several researchers stated that there were 21 (58,3%) patients with two-sided crossbite and (11,1%) patients with onesided crossbite The width of the maxillary alveolar process is an important index to diagnose and supervise the maxillary transverse deficiency treatment Handelman et al indicated that the horizontal dimension of the patients with posterior two-sided crossbite in those of it is 3-4 mm narrower than the average person The index on lateral cephalometric radiographs before treatment About the characteristics on lateral cephalometric radiographs of the maxillary transverse deficiency patients, this research indicated that the majority of parameters for the vertical and 18 anteroposterior assessment on the bone were actually similar to the average value Numerous index on CBCT This study uses the standards published in 2010 in order to diagnose the transverse deficiency of maxilla (The standards of Penn CBCT analysis concluded by Ryan K Tamburrino), which are commonly used by America and European countries because of the accuration and repetition According to the correlation standards between the maxillary and mandibular transverse dimension: the transverse width of maxilla is mm wider than that of mandible, in reality, there was an average 1,7 mm difference in the patients with the transverse deficiency 4.2 Evaluate the effectiveness of minivis assisted rapid palatal expansion 4.2.1 Treatment duration and clinical changes The expansion process would take place in 32,52 days The final result of each patient depends greatly on the specificity of the procedure, the clinical design of the miniscrews for that particular case The present case utilized the minivis MSE II, with a diameter of 0,8mm, equally with spins of 0.13 mm each The average opening of diastema is about 8,67 mm However, this index does not scale with the opening of diastema between two central incisors and 19 neither does the opening of maxillary The width of diastema between two central incisors at the end of the procedure is recorded at 3,5 mm According to observation, the split between two maxillary central incisors appeared on the 11th day of the process The inward tilting of those crowns was caused by the elasticity of the muscle cluster through the maxilla 4.2.2 Changes of the dimension of dental arch after expansion and months retention Our study indicated that the width of the upper dental arch process noticeably increased after activated time After months, these changes slightly decreased Choi et al (2016) believed that the width remarkably raised; the cuspid, the first premolar and the first molar respectively increased by 2,86 mm, 6,09 mm, 8,32 mm However, the width of the dental arch of maxilla significantly reduced after retention: the cuspid only raised by 2,38 mm, the first premolar raised by 4,16 mm (decreased by 31,7%) and the first molar raised by 4,42 mm (decreased by 46,8%) compared to the starting point of the process 4.2.3 Variation of the CBCT radiographs after expansion and months The maxillary lateral movement: The study’s results stated that the palatal expansion accounted for 67,34%, while the first molar and its alveolar bending accounted for 32,66% Same case was 20 recorded in other studies The maxilla was splitted on an unstable transverse plane The reason for asymmetrical movement outward of the palatal suture has not been proved Several researchers believed that it came from the asymmetry of the left and right maxilla Moreover, the existence of different forces, for instance chewing force from the one-sided crossbite cases, could lead to the one-sided lateral movement The changes of the pterygopalatine suture: The result showed the unfold between the internal and external pterygoid apophysis is found in 69,4% of patients based on the palatal plane The average opening is between 1,24 mm and 1,15 mm (to the right and left) Same results are pointed out by Cantarella, Ney, and Ozge Colak The rotation of the zygoma-maxilla suture: The result showed that the lower part of zygoma had more significant sideway movement than the upper part The statistics suggested that both bones moved outward and the center axis near the zygoma-frontal bone connection area The changes of the nasal cavity: The widening of maxilla might influence the nasal cavity The outcomes stated that the width of nasal cavity on the coronal plane and the axial plane through the lower nasal cavity increased its transverse dimension The other authors concluded similar results 21 The dental and alveolar bones changes: Although minivis is popularly used to strengthen anchor points, it would still put pressure directly on the bones However, the tooth would still be tilted, due to the tilting of the minivis inside the maxilla The tilting of those minivis is caused possibly by a little gap between minivis and designated screwing holes Influence on periodontal system: The high pressure of expansion might cause tension on the periodontal system of anchor teeth and buccal alveolar 4.2.3 Evaluate the vertical and anteroposterior changes on lateral cephalometric radiographs The index on lateral cephalometric radiographs before treatment, after expansion and months of retention were not significantly different This result was similar to those of several authors 4.2.4 Treatment results The outcomes of the maxillary expansion using MSE appliance on 36 patients: there were 34 patients with good treatment results (94,4%), patients with average treatment results (5,56%) Those outcomes still remained relevant in the following months after ceasing the expansion process 22 CONCLUSION Clinical and radiographic characteristics of patients with maxillary transverse deficiency 1.1 Clinical characteristics In 36 patients, the number of females is higher than that of males The mean age is 20,14 Type III occlusion has the highest percentage Some common clinical signs are: posterior tooth crossbite, narrow smile, teeth crowding, narrow arch shape, and impacted teeth The average width of the maxillary dental arch in the canine position is 34,13 mm, in the premolar position is 41,3 mm, and the first molar position is 52,26 mm 1.2 Radiographic characteristics Most of the parameters according to the cephalometric radiographs of the study group of patients doesn’t significantly differentiate when compared with the mean The average maxillary transverse dimension of the study group is 61,55 mm, which is 1,37 mm larger than the mandibular size The average expansion is 3,63 mm The average inclination of the maxillary alveolar bone is 104,94o-110,36o The average inclination of the maxillary first molar is about 95o Treatment effectiveness of maxillary transverse deficiency using minivis assisted rapid palatal expansion 2.1 Clinical changes Mean extension of the palatal joint at the time of extended stopping is 8.67 mm The average duration of treatment is 32.52 23 days The width of the gap between two incisors at the time of extended stopping is 3.50 mm The maxillary dental arch width increased markedly at the positions of canines, premolars and molars after jaw expansion After months of maintenance (T2), the dental arch width at the above positions tend to decrease slightly compared to the time of T1 2.2 The Changes on CBCT The expansion of the bone accounts for 67.34%, the remaining 32.66% is due to the tilt of the teeth and alveolar bone The extension of the palatal joint is parallel anterior and posterior, superior and inferior The shift of Maxillary bone to the sides is observed both in upper and lower face slices After months of maintaining, this movement is almost stable or only slightly changed Under the effect of the force of expansion, the palatal bone is bent, and the nasal cavity also expands in size After expansion, alveolar bone, right and left teeth are slightly tilted towards the cheek After months, these values have partially recovered The alveolar bone thickness on the buccal surface of the first molars on both sides decreased after expansion, and on the lingual surface of the first molars, there was a slight increase after the expansion and after months of maintenance The palatal-sphenoid suture shows signs of frontal and lateral displacement 2.3 The changes on cephalometric 24 The indexes of bone correlation assessment in the vertical and the anterior-posterior directions on the cephalometric radiographs at the time of T0, T1, T2 have differences, but the difference is not significant 2.4 The result of the treatment In 36 studied patients, 34 patients had good results, patients had average results RECOMMENDATION Topic: A study on maxillary transverse deficiency: clinical characteristics, X-ray and treatment effectiveness evaluation, using minivis assisted rapid palatal expansion determined that the appliance of palatal expansion achieved significant effectiveness in the fully grown as well as mature patients who acquired the maxillary transverse deficiency, nonetheless, we pointed out several recommendation: The palatal expansion appliance was long-term applied under the patients’ palate; they were instructed to activate on their own at home, thus, they were required to pay attention to oral healthcare as well as re-examination to supervise their activation and clean the appliance preventing the inflammation The research was performed with the attendance of 36 patients and in the duration of months after ceasing expansion, hence, we supposed that the next studies should extend sample size and increase management duration in order to more overall assess the results of MSE appliance as well as recurrence after removing it LIST OF PUBLISHED ARTICLE RELATING TO THESIS Pham Thi Hong Thuy, Vu Quang Hung, Vu Quang Hien (2021) Đặc điểm lâm sàng, xquang bệnh nhân hẹp chiều ngang xương hàm bệnh viện Đại học Y Hải Phòng năm 2020 Vietnam medical journal, 503, 6, 269-276 Pham Thi Hong Thuy, Trinh Thi Thai Ha, Pham Thi Thu Hang, Vu Quang Hung (2022) Description of changes in pterryopalatine suture on conebeam CT in patients after minivis supported maxillary expansion Vietnam medical journal, 514, 5(1), 36-40 Pham Thi Hong Thuy, Trinh Thi Thai Ha, Pham Thi Thu Hang, Vu Quang Hung (2022) Asessment of the vertical and anterioposterior changes on the cephalometric in patients after minivis supported maxillary expansion Vietnam medical journal, 514, 5(1), 119-123 ... mandibular plane angle (MPA), palatal plane angle (PPA), Y axis angle, angle between the palatal plane and the mandibular plane Anterioposterior rating parameters: Depth of the maxillary bone (FH-NA),... face (A-NPo), SNA angle (SN-NA), SNB angle (SN-NB), ANB angle (NA-NB) Parameters on CTCB films: Reference planes on CBCT: The maxillary Sagittal Plane (MSP): plane passing through the anterior... suture, respectively 16 3.1 .2 Cephalometric changes Table 3.3 9 Cephalometric changes after expansion time and retention time T0 T1 T2 p Vertical Anteroposterior Mean SD Mean SD Mean SD Face axis 88,86