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Objective:To compare the difference between virtual surgical planning(VSP)position and postoperative real position of maxilla and condyle,and to explore the degree of intraoperative realization of VSP after orthognathic surgery.Methods:In this study,36 patients with mandibular protrusion de-formity from January 2022 to December 2022 were included.All the patients had been done bilateral sagittal split ramus osteotomy(SSRO)combined with Le Fort Ⅰ osteotomy under guidance of VSP.The VSP data(T0)and 1-week postoperative CT(T1)were collected,the 3D model of postoperative CT was established and segmented into upper and lower jaws in CCMF Plan software.At the same time,accor-ding to the morphology of palatal folds,the virtual design was registered with the postoperative model,and the unclear maxillary dentition in the postoperative model was replaced.Then the postoperative model was matched with VSP model by registration of upper skull anatomy that was not affected by the opera-tion.The three-dimensional reference plane and coordinate system were established.Selecting anatomical landmarks and their connections of condyle and maxilla for the measurement,we compared the coordinate changes of marker points in three directions,and the angle changes between the line connecting the marker points and the reference plane to analyze the positional deviation and the angle deviation of the postoperative condyle and maxilla compared to VSP.Results:The postoperative real position of the maxilla deviates from the VSP by nearly 1 mm in the horizontal and vertical directions,and the anteropos-terior deviation was about 1.5 mm.In addition,most patients had a certain degree of counterclockwise rotation of the maxilla after surgery.Most of the bilateral condyle moved forward,outward and downward(the average distance deviation was 0.15 mm,1.54 mm,2.19 mm,respectively),and rotated forward,outward and upward(the average degree deviation was 4.32°,1.02°,0.86°,respectively)compared with the VSP.Conclusion:VSP can be mostly achieved by assistance of 3D printed occlusal plates,but there are certain deviations in the postoperative real position of maxilla and condyle compared with VSP,which may be related to the rotation axis of the mandible in the VSP.It is necessary to use patient personalized condylar rotation axis for VSP,and apply condylar positioning device to further improve surgical accuracy.
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Objective:To compare the effects of treatment with Hybrid-Hyrax-Facemask(FM)versus miniscrews in the anterior pal-ate combined with Hybrid-Hyrax-Facemask(MSI/FM)for patients with early Class Ⅲ malocclusion and maxillary deficiency.Methods:18 patients aged with early Class Ⅲ malocclusion and maxillary deficiency were randomly divided into 2 groups(n=9)and treated with FM and MSI/FM respectively.Alternating rapid maxillary expansion and constriction(Alt-RAMEC)protocol combined with a maxillary protraction force of 3.92 N was applied on each side of all patients from elastics connected to the facemask in a down-ward and forward direction of 30° to the occlusal plane.Iortho cephalometric software was used to analyze the data of lateral cephalo-grams of the patients before(T0)and after(T1)treatment.Results:Improvement was verified in the facial profile and occlusion of all patients.In MSI/FM group the average treatment time was shorter.There were significant differences(P＜0.05)between T0 and T1 in the following measurements in FM group:SNA,ANB,Co-A,Co-Gn,Wits,S-Go,Na-Me,MP,U1-SN,UADH,LADH,Overjet,UL-EP increased,U1-L1 decreased.There were significant differences(P＜0.05)between T0 and T1 in the following measurements in the MSI/FM group:SNA,ANB,Co-A,Wits,Na-Me,MP,Y-axis,U1-SN,Overjet,UL-EP increased,SNB,Co-Gn-Co-A,S-Go/N-Me,U1-L1,L1-MP decreased.Conclusion:Both FM and MSI/FM combined with Alt-RAMEC protocol and a maxillary protraction force are effective in the treatment for Class Ⅲ patients with maxillary deficiency.MSI/FM may produce more significant bone effect and re-duce dental compensation,promote more forward growth of midface and more improvement in the growth direction of mandible and re-duce compensatory lip inclination of anterior teeth in shorter treatment time.
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Objective@#To analyze the condylar and inclination of the occlusal plane features in skeletal Class Ⅲ malocclusion patients with mandibular asymmetry by using cone beam computed tomography(CBCT).@* Methods@#Forty eligible patients with Angle Class Ⅲ malocclusion were enrolled. All individuals were classified based on the distance from Me point to median sagittal plane. The left and right angles between OP and FH plane, the position and morphology of the condyle were measured in both groups.Then the data collected were statistically analyzed. @* Results@#Compared to the opposite side, there was a statistically significant difference(P<0.05) in angle between OP and FH plane, the anterior joint space, superior joint space, lateral joint space and condylar mediolateral diameter, with a higher proportion of joint posteriority in deviated side. Mandibular deviations were positively correlated with both the anterior joint space of the deviated side and the angle between OP and FH plane of the opposite side(P<0.01). There was no statistical difference between the left and right side of angles between OP and FH plane, the position and morphology of the condyle in skeletal Class Ⅲ patients without mandibular deviation(P>0.05); the joint was predominantly in anterior and middle position. @*Conclusion@#There is asymmetry on the left and right sides of the inclination ofocclusal plane, the position and morphology of the condyle of skeletal Class Ⅲ malocclusion patients with mandibular asymmetry. Compared with the opposite side, the deviated side has smaller angle between OP and FH plane and smaller condylar mediolateral diameter, and the condyle shows generally more posterior, inferior and inward movement in glenoid fossa. The inclination of the occlusal plane and the position of condyle are significantly and positively correlated with the distance from Me point to median sagittal plane.
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Objective:To evaluate and compare the outcomes of maxillary protraction treatment assisted by temporary anchorage devices (TADs) and removable biteplate in cleft lip and palate patients using cephalometric analysis.Methods:Fifty-four cleft lip and palate patients were divided into 3 groups based on different maxillary protraction treatments: bitepalate removable appliance group (group A), maxillary protraction treatment assisted by TADs group (group B) and control group (group C). Lateral cephalograms were taken at the start and the end of maxillary protraction. Skeletal, dental and soft tissue changes were measured using Dolphin software and compared between groups.Results:The average protraction time of groups A and B were (8.51±1.33) and (9.20±1.45) months ( P=0.146), respectively. A point moved forward by 4.08 mm in group A and 4.83 mm in group B were noted, without significant differences between the two groups. Compared to group C, ANB and wits was highly improved after protraction in groups A and B. U6-VRmx increased by 0.46 mm and U1-pp increased by 0.63 mm in group B, both of which were significantly smaller than those of group A (both P<0.05), suggesting that maxillary protraction treatment assisted by TADs could reduce molar advancement and upper incisor protrusion. Conclusions:Both maxillary protraction treatment assisted by TADs and removable biteplate could significantly improve skeletal class Ⅲ malocclusion in unilateral cleft and palate patients. Maxillary protraction treatment assisted by TADs could reduce molar advancement and upper incisor protrusion.
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Objective @#To study the effect of anterior traction on the temporomandibular joint in adolescent patients with skeletal Class Ⅲ malocclusion.@*Methods@#Twenty-nine patients with early permanent dentition with skeletal class Ⅲ malocclusions were measured by cephalometry and a coordinate system before and after maxillary protraction. The correlation between dentofacial structures and the temporomandibular joint was analyzed. @*Results @# After maxillary protraction, cephalometric measurements showed that the dentofacial structure changed significantly; ANB increased by 3.97° ± 2.32° (P<0.001); U1-SN increased by 4.97° ± 5.51° (P<0.001); L1-MP decreased by 1.26° ± 1.41° (P = 0.008); and MP-SN increased by 1.02° ± 3.90° (P = 0.003). The coordinate system measurement showed that the S-Fpx was decreased by 0.16 ± 1.52 mm (P = 0.041), the S-Ciy distance was significantly decreased by 0.09 ± 2.03 mm (P = 0.028), and there was no significant change in the temporomandibular joint spaces (A, P, and C) (P>0.05). Correlation analysis showed a moderate negative correlation between the posterior margin of the temporomandibular joint fossa and U1-SN (r = -0.427, P = 0.042). There was a moderate positive correlation between the leading edge of the condyle and ANB (r = 0.425, P = 0.043); there was no correlation between the joint space and dentofacial changes. @* Conclusion@#After treatment with maxillary protraction for adolescent skeletal class Ⅲ malocclusion, maxillary protraction had some effect on changes in the temporomandibular joint fossa and condyle and had no effect on the joint space.
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Objective @# To investigate the changes in the sagittal diameter of the upper airway before and after the treatment of skeletal Class Ⅲ malocclusion in adults with microimplant anchorage and class Ⅲ intermaxillary elastics and to provide a reference for clinical treatment. @*Methods @#A total of 35 adult patients with skeletal Class Ⅲ malocclusion were selected to be treated with the straight-wire technique. Microimplant group, 15 cases (group A): patients with severe skeletal Class Ⅲ malocclusion (vertical high angle) were treated with the straight-wire technique combined with microimplant anchorage; class Ⅲ intermaxillary elastics group, 20 cases (group B): Patients with mild or moderate skeletal Class Ⅲ malocclusion (vertical low angle and average angle) were treated with the straight-wire technique combined with class Ⅲ intermaxillary elastics, and cephalometric radiographs obtained before and after treatment in the upper airway in the two groups were measured and analyzed.@*Results @#Changes in cranial and maxillofacial measurements after correction: in group A, (sella-nasion-supramental angle) the SNB angle decreased significantly (P < 0.05), and (subspinale-nasion-supramental angle) the ANB angle increased significantly (P < 0.05). In group B, the SNB angle decreased significantly (P < 0.05), while (subspinale-nasion-subspinale angle) the SNA angle、ANB angle and anterior skull base plane-mandibular plane angle (Sn-MP) angle increased significantly (P < 0.05). Changes in sagittal diameter of the upper airway measurements after corrections: In group A, the width of the glossopharyngeal segment of the upper airway (TB-TPPW) decreased significantly (P < 0.05). In group B, first segment width of the upper airway behind the hard palate (PNS-R) increased significantly (P < 0.05). After correction, the decreased SNB and increased ANB in group A was higher than that in group B, and the difference was statistically significant （P < 0.05）. The decreased of TB-TPPW in upper airway of group A was greater than that of group B, and the difference was statistically significant （P < 0.05）.@* Conclusions @#In the treatment of skeletal class Ⅲ malocclusion with microimplant anchorage, the sagittal diameter of the glossopharyngeal segment of the upper airway has a negative impact.
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OBJECTIVE@#This study aimed to investigate the therapeutic effects and advantages of skeletal class Ⅲ malocclusion treatment by transmission straight wire technique.@*METHODS@#Ninety-seven patients who received treatment for skeletal class Ⅲ malocclusion at the Department of Stomatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology from January 2012 to January 2017 were selected for this retrospective study. All these patients refused surgery. They were divided into two groups in accordance with the type of skeletal malocclusion: mild-to-moderate skeletal malocclusion group (-4°≤ANB <0°) and severe skeletal malocclusion group (-8°≤ANB<-4°). Each of the two groups was divided further into two small groups in accordance with the technique used: T group (transmission straight wire technique) and M group (MBT technique).@*RESULTS@#The crossbite of all 59 patients in the mild-to-moderate skeletal malocclusion group was successfully treated. The molars were classified as classⅠrelationship, and the facial profile improved. Significant differences were found in the values of U1/SN angle, L1/MP angle, and Lip-Diff between the T and M groups before and after the treatment (P<0.05). The extent of incisor root resorption was lighter in the T group than in the M group (P<0.05). In the severe skeletal malocclusion group, the crossbite of all 38 patients was cured or partially cured. Fourteen patients showed severe lower anterior teeth inclination (five in the T group and nine in the M group), and the profiles did not significantly improve. Significant differences were observed in the values of U1-NA value, U1/SN angle, L1-NB value, L1/MP angle, LLP, and Lip-Diff between the T and M groups before and after the treatment (P<0.05). The extent of incisor root resorption was lighter in the T group than in the M group (P<0.05).@*CONCLUSIONS@#Relative to the MBT technique, the transmission straight wire technique has great advantages in improving facial profile, reducing the compensatory inclination of the upper and lower anterior teeth, and reducing the risk of root resorption in the treatment of skeletal class Ⅲ malocclusion.
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Humans , Cephalometry , Malocclusion , Malocclusion, Angle Class II , Malocclusion, Angle Class III , Maxilla , Retrospective StudiesABSTRACT
OBJECTIVE@#To assess the efficacy of bone anchorage and maxillary facemask protraction devices in treating skeletal class Ⅲ malocclusion in adolescents.@*METHODS@#Articles relating to the use of bone anchorage and maxillary facemask protraction devices for treating skeletal class Ⅲ malocclusion in adolescents were searched from the databases of Cochrane Library, PubMed, EmBase, CNKI, and Wanfang database. Several inclusion and exclusion criteria were developed for the article screening. The clinical data were extracted, and the quality of the selected articles was evaluated. A Meta-analysis of SNA, SNB, ANB, ANS-Me, Wits, and U1-PP change was performed by using RevMan 5.3.@*RESULTS@#Seven studies (264 patients) were included in the Meta-analysis. Among these studies, three were randomized controlled trials, and four were non-randomized controlled trials. Compared with the maxillary facemask protraction device group, the bone ancho-rage device group had higher SNA changes and lower ANS-Me, Wits, and U1-PP changes (P<0.05). No significant differences were observed in the SNB and ANB changes between these two groups.@*CONCLUSIONS@#Compared with the maxillary facemask protraction device, the bone anchorage device can increase the extent of protraction of the maxilla and has better controls for the labial inclination of the maxillary anterior teeth in treating skeletal class Ⅲ malocclusion among adolescents. However, additional high-quality randomized controlled trials must be performed to verify the results.
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Adolescent , Humans , Cephalometry , Extraoral Traction Appliances , Malocclusion, Angle Class III , Maxilla , Palatal Expansion TechniqueABSTRACT
@#For patients with dento-maxillofacial deformities who receive orthodontic-orthognathic combined treatment, the conventional treatment approach is preoperative orthodontic-orthognathic surgery-postoperative orthodontics. However, with the development of techniques used in orthodontic and orthognathic treatment, the surgery-first approach (SFA), namely, orthodontic surgery-postoperative orthodontics, has been widely used currently and displays several advantages, such as improving the treatment efficiency and providing patients with more satisfaction. This review provides a brief discussion and review of SFA concerning its development, indications, advantages and disadvantages, outcomes and stability, and the application and research progress of SFA in orthodontic-orthognathic combined treatment for patients with maxillofacial deformity. The literature review results showed that compared with the conventional treatment approach, SFA has relatively strict indications, which usually include patients with skeletal class Ⅱ/Ⅲ malocclusion, skeletal open bite, and bimaxillary protrusion or patients with facial asymmetry but who require little preoperative orthodontic treatment or removal of the compensation of the dental arch, specifically as follows: ①well-aligned to mildly crowded anterior teeth, ②flat to mild curve of Spee, ③normal to mildly proclined/retroclined incisor inclination, ④acceptable arch coordination, ⑤extensive occlusal contact between the upper and lower dentition requiring at least 3 occlusal contacts. Any occlusion that may affect the outcome of surgery or final result of the overall treatment, as well as any disease that may jeopardize the healing process after surgery, is regarded as a contraindication. Furthermore, SFA has potential disadvantages, such as a possible higher incidence of complications, including unstable occlusion and malunion of bones, which still require further research to be confirmed. Most researchers believe that no significant difference occurs between the outcome and stability of the two approaches. However, currently, we still need a sufficient sample size of prospective studies to provide accurate evidence.
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OBJECTIVE@#To investigate the effect of pre-surgical orthodontic treatment on temporomandibular joint (TMJ) in patients with skeletal class Ⅲ malocclusion treated with orthodontic-orthognathic surgical treatment.@*METHODS@#Twenty-four patients with skeletal class Ⅲ malocclusion who underwent orthodontic-orthognathic surgical treatment were included in the study. Before and after the completion of orthodontic treatment, the symptoms of TMJ were examined and recorded, and the short- and the long-axis diameter of the condylar (d), condylar height (h), joint space (L) at different angles, bilateral condylar spacing (R), and the condylar angles were measured, with scanning performed by using cone-beam computed tomography (CBCT). Then, the changes of TMJ symptoms and bone structure at different periods were analyzed.@*RESULTS@#No significant changes were observed in the joint symptoms before and after the pre-surgical orthodontic treatment. No significant changes were found in the measurements of the bone structure of TMJ in the dimensional direction (P>0.05).@*CONCLUSIONS@#In the orthodontic-orthognathic surgical treatment procedure, the pre-surgical orthodontic process does not have a significant effect on TMJ.
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Humans , Cone-Beam Computed Tomography , Malocclusion, Angle Class II , Malocclusion, Angle Class III , Mandibular Condyle , Temporomandibular JointABSTRACT
Objective To develop a Class Ⅲ twin-block magnetic orthopedic appliance (TMOA-Ⅲ) and to investigate the treatment effects of this appliance on skeletal Class Ⅲ malocclusion of mixed dentition and early permanent dentition.Methods The sample consisted of 76 Chinese children (42 males and 34 females,mean age 9.1 years) with Class Ⅲ malocclusion caused by maxillary retrognathism,and the subjects were divided into a treatment group and a control group.The treatment group,38 subjects (21 males and 17 females),were instructed to wear TMOA-Ⅲ for 5-8 months (mean 7.5 months) and the control group,38 subjects (21 males and 17 females),did not wear any appliance.Cephalometric radiographs were taken and measurement data were used for analysis.Results Compared with the control group,patients of the treatment group showed a favorable increase of maxilla length and anterior movement (PNS-A,P＜0.001;SNA,A-NPg,P＜0.05),and skeletal Class Ⅲ facial profiles improved (UL-EL,NsPgs-HL,Facial convexity,P ＜ 0.001;LL-EL P ＜ 0.005).Conclusions The results indicate that TMOA-Ⅲ is effective for the treatment of Class Ⅲ malocclusion caused by maxillary retrognathism in mixed dentition and early permanent dentition,which provides another choice for the treatment besides the face mask.
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<p><b>OBJECTIVE</b>To evaluate vertical stability after various orthognathic surgical treatment plans for skeletal class Ⅲ malocclusion with anterior openbite.</p><p><b>METHODS</b>A retrospective multicenter cohort study was conducted to investigate vertical stability after various orthognathic surgical treatment plans for skeletal class Ⅲ malocclusion with anterior openbite. From 2010-2016, 122 patients from two domestic stomatological hospitals were included in our study. Patients were divided into four groups according to their treatment plans, namely, bilateral sagittal split ramus osteotomy (BSSRO), intraoral vertical ramus osteotomy (IVRO), BSSRO+Le Fort Ⅰ, and IVRO+Le Fort Ⅰ. All patients followed a standardized examination procedure at 6 and 24 months post-treatment. The observation indexes include overbite, mandibular plane angle, and intermaxillary angle.</p><p><b>RESULTS</b>1) The significantly reduced ratio of the overbite in the BSSRO+Le Fort Ⅰ and IVRO+Le Fort Ⅰ groups were less than the BSSRO and IVRO groups at 6 and 24 months post-treatment. 2) The significantly increased ratio of the mandibular plane in BSSRO+Le Fort Ⅰ and IVRO+Le Fort Ⅰ groups were less than BSSRO and IVRO groups at 6 and 24 months post-treatment. 3) The significantly increased ratio of the intermaxillary angles in BSSRO+Le Fort Ⅰ and IVRO+Le Fort Ⅰ groups were less than the BSSRO and IVRO groups at 6 months post-treatment, while there was no statistical difference at 24 months post-treatment.</p><p><b>CONCLUSIONS</b>Bimaxillary surgery (BSSRO+Le Fort Ⅰ and IVRO+Le Fort Ⅰ) is more effective than mandibular surgery to control vertical relapse.</p>
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Objective:To evaluate the profile esthetics of children with skeletal class Ⅲ malocclusion treated with micro-implant.Methods:20 patients (12 boys and 8girls) aged 11-13 years were treated by micro-implant and maxillary protraction for 8 to 10 months.The profile esthetic indexes were measured on pre-and post-treatment cephalometric radiography.Results:The esthetic of the patients were remarkably improved after treatment.The factors that influence the esthetic index of children were the anteroposterior relationship of the maxilla,the mandible and the thickness of soft tissue.The results were stable 1 year after treatment.Conclusion:Maxillary protraction by micro-implant can improve the profile esthetic of children with Class Ⅲ malocclusion,correct over-bite and over-jet.
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Objective:To evaluate the clinical effect of distalizing mandibular dentition with micro-implant in patients with skeletal classⅢmalocclusion.Methods: In the study, 20 patients with skeletal class Ⅲmalocclusion were selected.They are consist of 8 males and 12 female with an age range from 16 to 38 years old and an average age of (21.5±5.6) years.They were treated with straight wire technique and the implant were inserted into the mandibular external oblique line to distlize the lower dentition to a class Ⅰmolar relationships.Cephalometrics films were taken before and after treatment.The changes of hard tissue and soft tissue were analyzed by evaluating 26 measurement measurements.Results: ClassⅠmolar relationships were achieved, and the profile were improved after treatment.ANB increased by(0.80±1.02)°,Wits increased by (1.67±1.74) mm,after treatment(P<0.05).The lower dentition were significantly retracted after treatment with L1-NB distance decreased by(2.64±1.50) mm, P<0.05;the mesial buccal cusp and mesial root of the lower first molars were retracted by (3.26±1.95) mm and (0.79±1.27) mm respectively (P<0.05);the mesial buccal cusp of the lower second molars were retracted by (3.06±1.80) mm (P<0.05).After treatment, mandibular teeth got up-righted distally.From incisors to molar, L1/MP, L5/MP, L6/MP, L7/MP angle decreased by(6.37±8.53)°, (10.59±8.50)°, (11.48±7.22)°, (15.72±7.16)°on average respectively (P<0.05), all of those changes had the statically significant effects.Soft tissue change after treatment, the distance from lower lip to esthetic plane were decreased by (1.70±1.59) mm on average (P<0.05).Conclusion: Distalizing mandibular dentition with micro-implant can get an satisfying result in patients with skeletal class Ⅲmalocclusion, the lower teeth were retracted by controlled tipping movement.
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An adolescent patient,in the peak of growth and development,with severe skeletal Class Ⅲ malocclusion and maxillary impacted canines was treated by removable and fixed appliances in the upper and lower dental arches.After treatment,the crossbite was relieved,the facial contour was improved,the integrity of the denture was kept and the Class Ⅰ molar relationship was achieved.
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Objective:To evaluate volumetric changes in the upper airway after orthodontic-bimaxillary surgery for the treatment of skeletal class Ⅲ malocclusion.Methods:Literatures about volumetric changes in the upper airway after orthodontic-bimaxillary surgery for the treatment of skeletal class Ⅲ malocclusion were searched from the database:Cochrane library,Embase,PubMed,Web of Science,Wangfang,China Science and Technology Journal Database (VIP),Chinese Biomedical Medicine Database (CBM) and China National Knowledge Infrastructure(CNKI).All the literatures were evaluated by Newcastle-Ottawa Scale(NOS) and analyzed by RevMan 5.3.Results:9 studies with 204 cases about volumetric changes in the upper airway after orthodontic-bimaxillary surgery for the treatment of skeletal Ⅲ malocclusion were included.Meta-analysis showed that after treatment there was no statistical difference about the nasopharyngeal volume change and the total volume change(P＞0.05);there was statistically significant difference about oropharyngeal volume change (P＜0.05).Conclusion:It might be better to consider orthodontic-bimaxillary surgery for skeletal class Ⅲ malocclusion with certain risk factors about OSAHS,but there was still a risk of airway narrow after orthodontic-bimaxillary surgery for skeletal class Ⅲ malocclusion.
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Objective:To evaluate the effects of maxillary protraction with or without rapid maxillary expansion in the treatment of Class Ⅲ malocclusion by Meta-Analysis.Methods:The randomized controlled trail,quasi-randomized controlled trail and the clinical controlled trail about the treatment of Class Ⅲ malocclusion by protraction with or without expansion were searched in the database of Cochrane Library,Embase,PubMed,Medline,CBM,Wan Fang,CNKI,VIP.2 authors qualified and extracted the data independently.Then the Meta-analysis was performed by using the RevMan 5.3 software.Results:7 studies with 228 cases were included,114 cases were treated by maxillary protraction with expansion and the other 114 cases by maxillary protraction without expansion.The Meta-analysis showed that:there was no significant difference in SNA,SNB,ANB and SN-PP except ANS-Me,U1-NA,SN-MP.A favorable improvement of the sagittal relationship between maxillary and mandibular was observed by using protraction whether with expansion or not.The expansion did not shorten the course of treatment,but it lowered the inclination of upper incisors,resulting in more clockwise rotation of mandibular plane and increase of the facial vertical dimension.Conclusion:Maxillary protraction with rapid maxillary expansion can be used in the treatment of class Ⅲ malocclusion with incisor labioclination.
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Objective To establish a mathematical model to describe the skeletal class Ⅲ malocclusion of patient dental and basal bone arch form, for providing a data reference and basis for further study. Methods Thirty-five patients with skeletal classⅢmalocclusion were selected in this study for computed tomography CBCT. The data of 3-D image were analyzed, and dental arch marker (Fa) and base bone arch marker (Ba) were determined. The reference plane was determined by least square method. Software Matlab 7.0 was used to calculate two-dimensional coordinate system. Based on this, a mathematical model was established to describe the dental and basal bone arch form and then to validate the mathematical model. Results (1) The mathematical model can be used to describe the dental arch form of skeletal classⅢmalocclusion, maxillary:Y=46.12 [1-(2X/70.99)2]1.052;mandibular:Y=39.16 [1-(2X/64.51)2]1.038. (2) The mathematical model can be used to describe the basal bone arch form of skeletal classⅢmalocclusion, maxillary:Y=43.14 [1-(2X/75.09)2]1.061;mandibular:Y=39.03 [1-(2X/60.63)2]1.021. (3) Fa was located at Ba labial side in the maxilla, the distance was positive. Fa was located at Ba lingual side in the mandibular, and the distance was negative. (4) The fitting correlation coefficient of beta-function curve and each tooth on the dental and basal bone arch of skeletal class Ⅲ malocclusion were greater than 0.7 (P<0.05). Conclusion In this study, the mathematical model can be used to describe the dental and basal bone arch form of the skeletal classⅢmalocclusion, which can guide further research.
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<p><b>OBJECTIVE</b>This study aims to compare the changes of hyoid bone position before and after treatment of Angle class Ⅲ malocclusion using improved appliance FR Ⅲ.</p><p><b>METHODS</b>Forty patients with Angle class Ⅲ malocclusion were chosen and divided into two groups, namely, experimental and control. Each group had 20 patients. The young patients in the experi-mental group were treated using improved appliance FR Ⅲ, whereas those in the control group were treated using classic appliance FR Ⅲ. The hyoid bone position of the two groups were comparatively analyzed using an X-ray film before and after treatment.</p><p><b>RESULTS</b>Compared with the condition before treatment, the condition after treatment showed that the hyoid bone position of young patients with Angle class Ⅲ malocclusion treated using improved appliance FR Ⅲ, H-FH, H-S, H-Ptm, and Ar-H-Me exhibited an increased angle (P<0.01), whereas the hyoid bone position of those treated using H-MP and H-Gn showed a decreased angle (P<0.01). The hyoid bone position of young patients with Angle class Ⅲ malocclusion treated using classic appliance FR Ⅲ, H-FH, H-S, and H-Ptm had an increased angle (P<0.05). Moreover, the hyoid bone position of those treated using Ar-H-Me had an increased angle (P<0.01), and the hyoid bone position of those treated using H-MP and H-RGn had a decreased angle (P<0.05).</p><p><b>CONCLUSIONS</b>Compared with the hyoid bone position before treatment, the hyoid bone position after treatment of the young patients with Angle class Ⅲ malocclusion treated using improved appliance FR Ⅲ may move backward and downward, and the mandibular and hyoid bone position may move through clockwise rotation. The mandibular and hyoid bone position of young patients with Angle class Ⅲ malocclusion treated using classic appliance FR Ⅲ obtained a large angle by moving clockwise. The man-dibular bone moves backward and downward, thereby improving the hyoid bone in backward and upward directions. This condition makes a significant difference in treating the hyoid bone position of young patients with functional Angle class Ⅲ malocclusion. .</p>
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Humans , Hyoid Bone , Malocclusion, Angle Class III , MandibleABSTRACT
An adult patient with skeletal crossbite and mandibular deviation was treated by mandibular molar distalization using micro-im-plant and intermaxillary traction.After treatment,the facial contour of the patient was improved,the Class Ⅰ molar and cuspid relationship was achieved.