| ObjectiveTo expand the lateral width of adult maxilla by non-surgical methods.In the first part,the three-dimensional reconstruction of CBCT(Cone Beam Computer Tomography)and the software of miniscrew guide plate are used to assist in the design of the bow expander.Three patients were taken as objects to complete the design process of the whole bow expander and the first-stage bow expansion therapy.In the second part,orthodontics combined with orthognathic surgery was applied to treat an adult case with lateral maxillary arch disorder(skeletal Class Ⅱ malocclusion).This study aims to select appropriate treatment methods based on the patient situation via analyzing the characteristics of two different adult dental arch expansion methods and improve the clinical effect of orthodontic treatment.Materials and methodsPart Ⅰ: Miniscrew assisted maxillary expansion guided by digital guide plateThree cases were selected from the author’s graduate study period,which met the maxillary expansion adaptation.They were used to assist rapid maxillary expansion with Miniscrew guided by digital guide plate.Case 1Patient Li,female,24 years old,complained of " irregular teeth" for treatment.The clinical manifestations are as follows: 1.Transverse: narrow upper and lower dental arch,bony upper and lower dental arch and dental irregularity;2.Sagittal direction: Angle Class Ⅱ,skeletal Class Ⅱ malocclusion,anterior teeth Ⅲ° deep overjet;3.Vertical: high angle,deep overbite with Ⅱ °;4.Others: crowded upper and lower dentition I.The treatment plan is as follows: in the first stage of treatment,miniscrew was used to assist rapid maxillary expansion and coordinate the width between upper and lower maxillary;In the second phase,fixed appliances were applied to remove the maxillary first premolars on both sides to align the upper and lower dentitions,to retract the upper incisors,to coordinate the molar relationship,to relieve the crowding of the maxillary dentition,to establish normal overbite and overjet,and to improve the profile and labial insufficiency.Case 2Patient Zhou,female,44,complained of " earth bag day" for treatment.The clinical manifestations are as follows: 1.Transverse: full dentition crossbite,lingual inclination of mandibular molars,skeletal disharmony of upper and lower dental arches,and stenosis of upper dental arch;2.Sagittal direction: Angle Class Ⅲ,skeletal Class Ⅲ malocclusion,I°crowding of maxillary dentition,reverse overjet of 1.5mm;3.Vertical direction: high angle,reverse overbite I°;4.Others: left deviation of mandibular midline is 2 mm.The treatment scheme is as follows: in the first stage of treatment,Miniscrew was used to assist rapid maxillary expansion to coordinate the width between upper and lower maxillary,and complete dentition crossbite is relieved;The second stage of treatment was fixed correction.Case 3Patient Lin,female,25 years old,complained of " buck teeth" for treatment.The clinical manifestations are as follows: 1.Transverse: narrow upper and lower dental arch,bony upper and lower dental arch and dental irregularity;Sagittal direction: Angle Class Ⅱ,skeletal Class Ⅱ malocclusion,anterior teeth with deep overjet Ⅲ°;3.Vertical direction: high angle;4.Others: maxillary dentition is I°crowded,mandibular dentition is Ⅲ° degree crowded,maxillary midline is 2mm to the left,mandibular midline is 1.5mm to the right.The treatment scheme is as follows: in the first stage of treatment,the maxillary dental arch is expanded by miniscrew to coordinate the width between upper and lower maxillary;The second stage of treatment is to align the upper and lower dentition as much as possible through orthodontic masking treatment,adduce the maxillary anterior teeth,and improve the profile.Before operation,all three patients need to take full dentition CBCT with complete maxillary structure and scan the plaster model before expansion.CBCT data and digital model are imported into implant guide software for registration(registration accuracy is 0.1mm),and appropriate implant site,implant depth and implant direction are selected with the aid of digital software.According to the measurement data of bone thickness and mucous membrane thickness in the implantation area,4 suitable miniscrews(2 * 10 mm)were selected.Finally,the resin guide plate is printed in 3D and then cast into the base of the bow expander.After welding the spiral bow expander,the personalized guide plate is made to guide the minscrew to assist MARPE.After the bow expander is properly tried on,the miniscrew is implanted at the appropriate time and the bow expander is installed,and the bow is expanded at a speed of 0.5mm/ day twice a day.The course of bow expansion is determined according to the degree of lateral disharmony,and the palatal base is maintained after the treatment.After the expansion of the arch,the patient’s full dentition CT and model including the maxilla were collected,and the facial and intraoral photos were taken.The models of patients before and after bow expansion were compared,and the therapeutic effect was evaluated with CBCT.Part Ⅱ: Orthodontic treatment combined by orthognathic surgery for adult skeletal malocclusion Ⅱ with transverse maxillary arch imbalanceCase 4Patient Wei,female,22 years old,complained of " bad occlusion and buck teeth affecting beauty" for treatment.The clinical manifestations are as follows: 1.Transverse: the transverse width of maxillary and mandibular arches is slightly irregular;2.Vertical direction: high angle,deep overjet I;3.Sagittal direction: Class Ⅱ of Angle,skeletal Ⅱ malocclusion,Deep Anterior Teeth overbite Ⅲ;4.Other: The lower dentition is crowded I,the maxillary midline is 0.5mm to the left,and the mandibular midline is 2mm to the right.The treatment plan is as follows: orthodontic orthognathic combined treatment,preoperative orthodontic decompensation treatment,conventional fixed appliance technology to expand the maxillary arch,level the upper and lower dentition,decompensation after the upper Le Fort I block osteotomy+BSSRO(bilateral sagittal split ramus ostetomi bilateral mandibular ramus sagittal osteotomy)+genioplasty,and orthodontic fine occlusal was performed after operation.ResultsPart Ⅰ: Miniscrew assisted maxillary expansion guided by digital guide plateCase 1Patient Li: after the first stage of treatment,the axial angle of maxillary bilateral first molars did not change from-17.9 °to-18.1 °,and the width of nasal base(between teeth 16 to 26)increased by 4.6mm from 27.5mm to 32.1mm;The axial angle of maxillary bilateral first premolars basically did not change from-23.3 °to-24.5 °.The average increase of palatal suture was 4.35 mm.The maxillary first molar basically maintained its original inclination,and the amount of bone expansion was larger than that of dental expansion.Case 2Patient Zhou: after the first stage of treatment,the axial angle of maxillary bilateral first molars increased by31.1 °from 4.9 °to 36.0 °,and the width of nasal base(between teeth 16 to 26)increased by 0.7mm from 19.6mm to 20.3mm;The axial angle of maxillary bilateral first premolars increased by 17.6 °from-13.5 °to 4.1 °.Medial palatal suture increased by 1mm on average.The buccal inclination of bilateral first molars is about 30 °,the increase of palatal suture and nasal base width is less,and the dental expansion is larger than the osseous expansion.Case 3Patient Lin: after the first stage of treatment,the axial angle of maxillary bilateral first molars increased by 18.5 from 20.0 to 38.5,and the width of nasal base(between teeth 16 to 26)increased by 1.4mm from 25 mm to 26.4mm;The axial angle of maxillary bilateral first premolars increased by 11.6 from-6.5 to 5.1.The median palatal suture increased by 0.8mm on average.The buccal inclination of bilateral first molars is about 30,the increase of palatal suture and nasal base width is less,and the dental expansion is larger than the osseous expansion.Part Ⅱ: Orthodontic treatment combined by orthognathic surgery for adult skeletal malocclusion Ⅱ with transverse maxillary arch imbalanceCase 4Patient Wei: bilateral canine width increased by 6.7mm;after treatment;The width of bilateral first bicuspid increased by 3.8mm;Bilateral first molars increased by 1.8mm;The width of maxillary arch base bone increased by 2.0 mm.Anterior overbite and overjet are normal,teeth are arranged orderly,good occlusal relationship is obtained,and soft tissue profile is improved.Conclusions1.The jawbone data measured in CBCT was transferred to the digital model to make the digital guide plate,and the personalized guide plate was made by 3D printing technology to guide the introduction of miniscrew,which not only facilitates the clinical treatment operation,but also improves the accuracy of minisrew implantation.Reduce the blindness of plaster model introduction.2.Miniscrew anchorage penetrates through the maxillary double-layer cortical bone can achieve a better effect of bony arch expansion.Separating the palatal suture to the greatest extent can improve the disharmony between the upper and lower maxillary base bones.At the same time,because the maxillary molars and base bones can maintain a certain buccal inclination,the vertical height increase is avoided.3.When the miniscrew cannot penetrate through the maxillary double-layer cortical bone,it is difficult to effectively expand the maxillary bone transverse width regardless of the number of miniscrews.In addition,the height of the contact point of the micro-implant abutment and the abutment from the palatal due to the impedance center may be one of the factors affecting the effect of bone reaming.However,a small amount of separation can also be achieved by palatal suture expansion with a palatal base,the extension of dental arch width was mainly achieved by the change of dental inclination,and the increase of vertical height was obvious.4.Conventional fixed orthodontic technology combined with arch wire can also expand dental arch well,which has little influence on the morphology of hard palate,but the dental effect is obvious.It is suitable for patients with small amount of irregular bone width or irregular dental width,as well as patients with long treatment period and less crowding. |
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