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MINISTRY OF EDUCATION AND TRAINING MINISTRY OF DEFENCE 108 INSTITUTE OF CLINICAL MEDICAL AND PHARMACEUTICAL SCIENCES - TRAN THI KIM LIEN RESEARCH EFFECTIVE TREATMENT OF CLASS II MALOCCLUSION USING ANCHORAGE BY MINI-IMPLANT IN PATIENTS WITH EXTRACTION PREMOLARS Specialization: Odonto-Stomatology Code: 9720501 SUMMARY OF THESIS DOCTOR OF ODONTO-STOMATOLOGY Hanoi – 2023 THE THESIS WAS DONE IN: 108 INSTITUTE OF CLINICAL MEDICAL AND PHARMACEUTICAL SCIENCES Supervisor: Dr Pham Thi Thu Hang Dr Vo Thi Thuy Hong Reviewer: Assoc.Prof.Dr Nguyen Thi Thu Phuong Assoc.Prof.Dr Pham Thu Hien Assoc.Prof.Dr Pham Nhu Hai This thesis will be presented at Institute Council at: 108 Institute of Clinical Medical and Pharmaceutical Sciences 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 Class II malocclusion accounts for about 7.9%-42.9%[1] (average 20.9%) in the community, according to Nguyen Hung Hiep (2021)[2].The rate of class II malocclusion in Vietnam is 38.7%, this is one of the main reasons why patients come for orthodontic treatment and examination The cause of this type of malocclusion is underdevelopment of the lower jaw and/or the upper jaw, and/or the teeth Class II malocclusion can have a great impact on health and quality of life such as occlusal trauma, reduced chewing function, facilitated the onset of some oral diseases and affected facial aesthetics [3] The goal of orthodontic treatment for class II malocclusion is to achieve aesthetic three-dimensional facial harmony, a straight facial expression when viewed from the side, and functionally to achieve an oblique occlusion In which, depending on the cause and the growth stage of the patient, there are different treatment methods such as orthodontic treatment with appliances to eliminate bad habits, move away from the first molar, correct the growth of the teeth Development of the jawbone, compensatory treatment by extraction of premolars or orthopedic surgery For skeletal type II malocclusion, the facial projection will change only very little if the tooth is not extracted Therefore, in order to reduce the protrusion in patients with high facial protrusion, it is almost always indicated to extraction of premolars with requiring maximum anchorage [4],[ 5] MI is often used to create absolute anchorage in cases of class II malocclusion with indication for extraction of premolars The treatment plan for each class II malocclusion patient with indication for premolar extraction and anchorage with MI should be carefully explored and have different specific treatment strategies to achieve three-dimensional aesthetics and function In particular, the control of the vertical aspect of the face in orthodontic treatment should be carefully considered because increasing the height of the lower face is an unfavorable factor in hyperdivergent patients, the lower face is long, leading to the mandibular rotates downward, making the patient's face longer, greatly affecting the aesthetics and increasing the open bite In contrast, in cases with hypodivergent (hypodivergent patients) and short lower face, the treatment to reduce the height of the lower face makes the face shorter and bite deeper.[6-8] Amiri (2021)[9]reported the results of an anchorage study of Mini-implants better when controlling vertical tooth movement In Vietnam, although it has been widely indicated in recent years, there are not many reports on the application of Mini-implants in the treatment of class II malocclusions with indications for premolar extraction, but no research has any study on the effects of vertical resizing and face elements Therefore, we carried out the study " Research effective treatment of class II malocclusion using anchorage by Mini-implant on patients with extraction premolars" with the goal: Describe clinical characteristics, radiographic images of patients with class II malocclusion with indications for premolar extraction and anchorage by Mini-implant Evaluation of the effectiveness of treatment of class II malocclusion with anchorage by Mini-implant on patients with extraction of premolars with hyperdivergent, hypodivergent, normodivergent groups Chapter OVERVIEW 1.1 Class II malocclusion 1.1.1 Epidemiology 1.1.2 Class II malocclusion classification - According to analysis of cephalometric films: Occlusion class I skeletal (0° ANB < 3.6°), skeletal class II (angle ANB > 3.6°), skeletal class III (ANB angle < 0°).[17] Vertically the face evaluated by the GoGnSN angle is the angle between the SN skull base and the mandibular plane (Go-Gn) according to Steiner Class II malocclusion divides into three groups: hyperdivergent(Hyperdivergent with GoGnSN >37°); normal jaw angle (Normodivergent with 28°≤GoGnSN≤ 37°) and closure jaw angle (Hypodivergent with GoGnSN9m, patients with four small molars with an overbite of 7.1-9mm accounted for a low rate of 15.4 %, the majority of patients with indication to extract small molars have overbite 3.6°, growth stage Cs4 or more, convex face type, pointed lip angle Patients with hypodivergent have a GoGnSN < 28º, patients with normodivergent have 28º≤ GoGnSN ≤37º, patients with hyperdivergent have GoGnSN >37º The patient was treated with orthodontic treatment with brackets and indicated premolars extracted and anchored by MI The patient did not have facial malformations, jaw bone deformities The patient has a complete medical record and cephalometric films before treatment (time T1) and after treatment (time T2), plaster samples before and after treatment Parents/guardians of patients under 18 years of age and patients over 18 years of age agreed to participate in the study 2.1.2 Exclusion criteria History of Titanium Allergy History of maxillofacial trauma Patient is indicated for orthopedic surgery 2.2 Research Methods Objective 1: Cross-sectional descriptive study with clinical intervention, no control Objective 2: Clinical intervention study, controlled between three groups The study sample was collected by convenience sampling and retrospective combined prospective 2.2.1 Study sample size 2.2.2 How to perform Recovery team: Look up research information from medical records and archives Contact patients to check, evaluate results and make a list of patients, measure, analyze and evaluate through facial images, jaw samples and Panorama films, Cephalometric films before and after treatment Research group: Selecting patients, with patients in the process of treatment, clinical examination, monitoring, measurement, analysis through facial images before treatment, jaw samples and Cephalometric films as research medical records For patients starting to visit and treat, clinical examination, paraclinical examination and medical records are made Make a list of patients, perform treatment and follow-up Evaluation, measurement, analysis through facial images, jaw samples and Panorama film, Cephalometric film before and after treatment 2.2.2.1 Preparation patients 2.2.2.2 Detailed clinical examination 2.2.2.3 X-ray film analysis 2.2.2.4 Treatment Tools and equipment: set of examination trays forks, probes, mirrors Set of 3M-USA brackets, Nitium wire 0.12; 0.14; 0.16; 0.18 of 3M, SS arch wire of 3M-USA 016x022/25,017x025,019x25 Mini-implant Jeil- Korea size 16x8, 16x10 Closed springs about Morelli- Brazil, 3M-American chain, Dentos- Korea hook Reverse Niti Wire – Ortho Technology USA *Pre-orthodontic treatment Stable treatment of tooth decay, pulpitis Take tartar, clean teeth, treat periodontal if any Orthodontic treatment The patients in the study were fitted with brackets, the size of the bracket groove was 0.022"x0.028" Stage of straightening and straightening teeth: Align teeth and correct vertical asymmetry by flattening the arch This stage uses elastic NiTi or CuNiTi archwires with sizes 012, 013, 014, 016, 016x022/25, 017x025, 019x025 respectively depending on the degree of crowded teeth Replace wires 4-8 weeks apart until teeth are aligned Adjust the Spee curve by attaching stitches or the second molar tube from the beginning, using Reverse NiTi wire If the lower incisors are protruding or deepbite due to the upper incisors, use MI inserted in the position between the two upper middle incisors or between the 2-3 lower teeth Intervention stage: After straightening and flattening the teeth at wire stage 019x025 SS, insert the MI at the position between the first molar and second premolar or between the first and second molars at an average of 8-10mm compared to the bowstring Hypodivergent (hypodivergent) group used 12mm hook, medium jaw angle (normodivergent) group used 8mm hook, hyperdivergent group used 2mm hook, MI size: 1.6x8mm or 1.6x10mm inserted in the middle of the first molar and second premolar or between the first and second molars 1.4x8mm inserted between the upper middle incisors or the second and lower three incisors, in case of an open bite, it is necessary to depress the first and second molars of the upper jaw more, adding MI on the inner surface between the two molars above The pulling force on the MI is 250grams, instant loading immediately after plugging in Patients were re-examined every 4-6 weeks according to the treatment regimen Monitor MI during treatment for pain, discomfort, inflammation around MI, loosed MI End of treatment: remove brackets, clean teeth, take impressions, take pictures, take Cephalometric films after treatment Measure and record indicators after treatment 2.2.2.5 Evaluation of treatment results Clinical features Paraclinical features On the Panorama film, count the number of teeth on the arch, the general endodontic and periodontal problems of the teeth on the jaw Evaluation of treatment effectiveness and vertical control is based on the following components: Occlusion: The study used the PAR index to evaluate the results of treatment of malocclusion PAR(degree of change)= PAR before treatment - PAR after treatment Evaluation of changes in bones, teeth, and software on cephalometric cephalometric radiographs after treatment and comparison with pre-treatment index 11 Dental arch shape distribution related to sex Square arch shape is not present in male patient but there are 20 oval dental arches and 10 triangular dental arches out of total 30 dental arches of male patient The female patient has square, 77 oval and 23 triangular dental arches out of a total of 108 female dental arches 3.1.2.3 Occlusion characteristics according to PAR index Features of occlusion before treatment: Table 3.3 Occlusion characteristics according to PAR index Group PAR before treatment Crowedness of the upper anterior teeth The crowedness of the lower anterior teeth Overjet Overbite Midline The right occlusion posterior teeth area The left occlusion posterior teeth area Total PAR GHĐ Group x s (n=12) GHM Group (n=27) Total GHTB Group (n=30) 8, 33 4,14 9, 96 2, 74 6, 53 2, 66 (n=69) 8,19 3,33 7,17 2, 59 7, 67 3, 28 5, 33 3, 06 6,57 3,22 2, 08 1, 44 1, 33 1, 07 0, 75 0,87 2, 25 1, 1, 44 1,16 1, 1, 24 1,11 0, 89 2,89 1, 65 1, 57 1, 33 1, 02 0, 97 0,89 0, 1, 24 1,61 1,17 0,99 1,91 2, 25 1, 2, 1, 82 0, 77 1,1 1,78 1,74 38,17 10, 34 38, 93 8, 59 28, 11,12 34,45 10,95 1,29 1,11 0,88 1,72 3.2 Characteristics on Cephalometric film before treatment 3.2.1 Characteristics of bone indexes: Table 3.5 Bone indices on Cephalometric film Group Index SNA (°) SNB (°) GHD Group Group GHM GHTB group (n=12) (n=27) (n=30) 87.83±4.31 81.96±4.08 80.06±14.59 85.82±2.75 75.94±2.82 79.13±2.42 Total (n=69) P 83,91 9,89 0.00 (M) 78,37 3,62 0.00 12 ANB (°) NBa-PtGn(°) GoGn-SN(°) Md-FH(°) PP-Md(°) A-y axis(mm) B-y axis(mm) Pog-y axis (mm) AN Perp(mm) Pog- N Perp(mm) ANS-Me(mm) Wits 5.79±1.32 89.8±3.39 25.17±2.65 18.37±3.13 20.21±3.22 66.67±8.51 61.37±9.67 62.17±9.66 5.37±2.07 -0.08±5.2 61.17±7.75 2.42±2.24 6.87±1.92 81.4±3.36 40.22±2.24 29.02±3.47 31.26±3.11 60.37±5.78 49.8±6.3 48.19±6.2 4.2±2.48 -4.74±5.4 65.33±6.91 2.65±1.69 6.7±1.61 84.15±2.8 33.92±2.14 24.42±3.72 26.12±3.36 63.22±4.44 54.52±4.42 53.58±4.3 5.45±3.12 -2.28±4.25 62.92±5.93 1.33±2.74 6,61 1,71 84,05 4,27 34,86 5,78 25,17 5,13 27,1 5,09 62,7 6,16 53,86 7,44 52,97 7,86 4,95 2,75 -2,86 5,11 63,56 6,74 2,04 2,34 0.18 0.00 0.00(M) 0.00 0.00 0.024 0.000 0.000 0.249(M) 0.02 0.252 0.331 3.2.2 Features of dental indicators: Table 3.6 Dental indices on Cephalometric film Group Index U1-SN(°) U1-ANSPNS(°) L1-Md(°) U1-L1(°) Is- y axis (mm) Ii – y axis(mm) Ms- y axis (mm) Mi- y axis (mm) GHTB group (n=30) 109.35±8.53 118.17±10.17 113.68±7.53 118.93±6.62 124.71±6.13 122.17±7.44 97.07±6.59 102.71±4.15 102.67±5.53 112.3±10.41 111.71±6.49 110.8±9.11 64.94±6.85 74.42±8.9 68.92±6 60.83±6.83 68.75±10.43 64±5.4 37.88±5.11 46.74±8.41 40.87±4.71 37.96±5.64 44.71±8.83 40.45±5.29 GHD Group Group GHM (n=12) (n=27) Total (n=69) 112,77 8,88 121,34 7,15 100,49 6,32 111,54 9,17 68,32 7,58 63,59 7,46 40,72 6,36 40,22 6,5 P 0.011 0.044 0.01 0.83 0.01 0.007 0.000 0.009 3.2.3 Characteristics of soft tissue indicators: Table 3.7 Soft tissue index on Cephalometric film Group Index Angle of nose and lips(°) Ls-E(mm) Li-E(mm) Ls- y axis (mm) Li- y axis (mm) Pog'- y axis (mm) Total GHD Group Group GHM GHTB group 90.00±11.35 91.48±12.57 89.62±15.31 90,41 13,49 0.871 2.08±1.82 3.25±3 83.29±10.25 81.00±11.16 73.42±10.65 1.77±1.74 4.35±2.11 75.13±7.04 71.8±7.12 61.04±6.69 2.43±1.98 4.4±1.73 78.17±5.89 75.1±5.57 65.47±4.74 2,11 1,86 4,18 2,15 77,87 7,67 74,83 7,95 65,12 7,99 (n=69) P 0.411 0.259 0.018 0.010 0.000 13 3.3 Indications for tooth extraction 3.3.1 Indications for tooth extraction in patients with closed, open and moderate jaw angles: Table 3.8 Indications for tooth extraction in three groups of patients Indications for tooth extraction GHĐ GHM GHTB Total Group Group group (n=69) (n=12) (n=27) (n=30) Extraction 4th teeth upper jaw first Extraction 4th teeth two jaws 17 15 39 Extraction upper 4th teeth and ten 5th teeth lower Other 6 13 12 27 30 69 Total 3.3.2 Indications for tooth extraction according to the degree of overbite: In the study group, the number of patients with overbite under 5mm accounted for the largest number with 39/69 = 56.5% of the total number of patients The number of patients with overbite greater than 9mm accounted for the least number with 6/69 = 8.6% of the total number of patients Indication for extraction of upper 4th teeth is chosen mainly for patients with overbite greater than 5mm (with 6/7 = 85.7% of patients having upper 4th teeth extraction with overbite greater than 5mm) Patients with overbite under 5mm were assigned to extract 4th teeth, accounting for 28/69 = 40.6% of the total number of patients in all three groups There were 39 cases indicated extraction of two upper 4th teeth with overbite less than 5mm in total 69 patients studied, accounting for 14 56.5% Including cases (1 case of missing teeth of 12 and 22, cases with hidden canine tooth but the family and patient did not want to pull the underground tooth and chose to extract it, cases lost a first molar prematurely broken and the root due to tooth decay) There were 11 cases of extraction of two upper 4th teeth with overbite from 7.1-9mm out of a total of 69 patients studied, accounting for 16% Indications for extraction of upper 4th teeth and lower 5th teeth are distributed quite similar among the groups of patients with overbite at different levels 3.4 Treatment results 3.4.1 The change of PAR index in the group of patients with hypodivergent: Table 3.10 PAR index before and after treatment of closed jaw group (GHĐ) Group Before Occlusion treatment characteristics Crowedness of the 8.33±4.14 upper anterior teeth The crowedness of the 7.17±2.59 lower anterior teeth Overjet 2.08±1.44 Overbite 1.33±1.07 Midline 0.75±0.87 The right occlusion 2.25±1.6 posterior teeth area The left occlusion 2.25±1.6 posterior teeth area Total PAR 38.17±10.34 GHĐ Group After Efficiency treatment Index 1.08±1 -7.25±4 0.000 0.83±0.83 -6.33±2.19 0.000 0.00±0.00 0.00±0.00 0.00±0.00 0.17±0.58 -2.08±1.44 -1.33±1.07 -0.75±0.87 -2.08±1.73 0.000(W) 0.000(W) 0.000(W) 0.000(W) 0.00±0.00 -2.25±1.6 0.000(W) 2.25±1.87 -35.5±10.24 0.000 P 3.4.2 The change of tooth index on Cephalometric film of the group of patients with hypodivergent: The mean angle of U1-SN, U1-ANSPNS decreased after treatment (-6.94±8.5°; -8.44±8.38°), the incisor axis tilted more 15 tongue, statistically significant with p0.05 has no statistical significance The average ANS-Me distance increased after treatment (before treatment 61.17±7.75 mm, the result after treatment was 63.21± 7.18 mm), statistically significant with p0.05) The average angle of the nose and lips increased (12.62°±9.27°), decreased the convexity of the face when looking at the side, statistically significant p
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