Age dependence of the maturation of the midpalatal suture in the stability of orthodontic anchoring screws.

INTRODUCTION: Orthodontic anchoring screws (OASs) have been placed around midpalatal sutures in patients of various ages. Our previous study found that OAS placement more than 1.5 mm from midpalatal suture was more successful than placement directly at the suture. This study aimed to investigate the relationship between age and midpalatal suture maturation, considering factors affecting the failure of OASs using cone-beam computed tomography. METHODS: In total, 150 patients who underwent cone-beam computed tomography were selected. The total depth and sutured depth of the midpalatal suture corresponding area to anterior (interpremolar zone) and posterior region (mesial and distal borders of the first molar) were measured, and the ratio of sutured depth to total depth (sutured ratio) was calculated. RESULTS: The mean sutured ratios at interpremolar zone and mesial and distal borders of the first molar according to age were 40%, 60%, and 63% in the younger group (≤17 years), 46%, 76%, and 76% in the middle group (18-25 years), and 47%, 74%, and 76% in the older group (≥26 years), respectively. The sutured ratio of the anterior region was significantly lower than that of the posterior region (P <0.01). Each mean sutured ratio of the middle and older group was significantly higher than that of the younger group on both sides (P <0.01). According to the cervical vertebral maturation, the mean sutured ratio of cervical vertebral stages 5-6 was significantly higher than cervical vertebral stages 1-3 on the distal side (P <0.05). CONCLUSIONS: Incomplete closure of the midpalatal suture was observed frequently, even in the older group. This might be caused by insufficient calcification of the midpalatal suture, including in elder patients. To prevent OAS placement to the unsutured area, the midpalatal suture should be avoided regardless of age.

Low-intensity pulsed ultrasound enhances the rate of lateral tooth movement and compensatory bone formation in rats.

INTRODUCTION: Because mechanical stimulation of the periodontal ligament by low-intensity pulsed ultrasound (LIPUS) has been shown to increase the speed of bone remodeling, this study aimed to examine the effects of LIPUS stimulation on the rate of tooth movement and bone remodeling during lateral tooth movement. METHODS: Twelve-week-old Wistar rats were divided into 2 groups. The LIPUS group received experimental tooth movement with LIPUS stimulation, and the tooth movement (TM) group were provided experimental tooth movement without LIPUS. For each group, the upper right first molars were moved buccally with fixed appliances. LIPUS exposure was placed in the region corresponding to the right maxillary first molar. Three days after tooth movement, tartrate-resistant acid phosphatase was examined. Fourteen days after tooth movement, the intermolar width, bone mineral content, and bone volume fraction were analyzed by micro-computed tomography, and newly formed bone was measured histomorphometrically. RESULTS: The number of TRAP-positive cells in the compressed region was higher in the LIPUS group. The intermolar width was significantly higher in the LIPUS group than in the TM group. The alveolar bone around the maxillary first molar showed no differences in bone mineral content and bone volume fraction between the LIPUS and TM groups. The LIPUS group exhibited a more significant amount of newly formed alveolar bone than the TM group. CONCLUSIONS: The present study provides evidence of the beneficial effects of LIPUS on the lateral tooth movement.

Essential roles of G9a in cell proliferation and differentiation during tooth development.

Teeth develop through interactions between epithelial and mesenchymal tissues mediated by a signaling network comprised of growth factors and transcription factors. However, little is known about how epigenetic modifiers affect signaling pathways and thereby regulate tooth formation. We previously reported that the histone 3 lysine 9 (H3K9) methyltransferase (MTase) G9a is specifically enriched in the tooth mesenchyme during mouse development. In this study, we investigated the functions of G9a in tooth development using G9a conditional knockout (KO) mice. We used Sox9-Cre mice to delete G9a in the tooth mesenchyme because Sox9 is highly expressed in the mesenchyme derived from the cranial neural crest. Immunohistochemical analyses revealed that G9a expression was significantly decreased in the mesenchyme of Sox9-Cre;G9afl/fl (G9a cKO) mice compared with that in Sox9-Cre;G9a fl/+(control) mice. Protein levels of the G9a substrate H3K9me2 were also decreased in the tooth mesenchyme. G9a cKO mice showed smaller tooth germ after embryonic day (E) 16.5 and E17.5, but not at E15.5. The developing cusp tips, which were visible in control mice, were absent in G9a cKO mice at E17.5. At 3 weeks after birth, small first molars with smaller cusps and unseparated roots were formed. Organ culture of tooth germs derived from E15.5 cKO mouse embryos showed impaired tooth development, suggesting that tooth development per se is affected independently of skull development. BrdU labeling experiments revealed that the proliferation rates were decreased in the mesenchyme in G9a cKO mice at E17.5. In addition, the proliferation rates in the tooth inner enamel epithelium were also decreased. In situ hybridization revealed altered localization of genes associated with tooth development. In cKO mice, intensively localized expression of mRNAs encoding bone morphogenic protein (Bmp2 and Bmp4) was observed in the tooth mesenchyme at E17.5, similar to the expression patterns observed in control mice at E15.5. Localization of Shh and related signaling components, including Gli1, Ptch1, and Ptch2, in the tooth mesenchyme of cKO mice was generally similar to that at earlier stages in control mice. In addition, expression of Fgf3 and Fgf10 in the mesenchyme was decreased in G9a cKO mice at P0. Expression levels of Fgf9 and p21, both of which were expressed in the secondary enamel-knot, were also decreased. Thus, the expression of genes associated with tooth development was delayed in cKO mice. Our results suggest that H3K9MTase G9a regulates cell proliferation and timing of differentiation and that G9a expression in the tooth mesenchyme is required for proper tooth development.

Lip Morphology in Patients With Facial Asymmetry Can Be Corrected by 2-Jaw Surgery.

PURPOSE: Surgical orthodontic patients with facial asymmetry frequently show asymmetry of the lips, and this is often a major complaint of patients. This study investigated whether lip asymmetry associated with the maxilla and mandible was improved when 2-jaw surgery was performed in surgical orthodontic treatment. MATERIALS AND METHODS: Inclusion criteria for this retrospective cohort study were 1) an anteroposterior maxillary relation defined as skeletal Class I; 2) menton (Me) tranverse deviation greater than 5.0 mm; 3) maxillary cant greater than 3.0°; and 4) 2-jaw surgery. Primary predictor variables in this study were skeletal morphologic measurements (Me deviation, maxillary cant, and maxillary distance ratio) before and after treatment. Outcome variables were lip morphology measurements (labial commissure distance, lip angle, and lip area). Additional variables included age and gender. Vertical distances, angles, and area of the upper and lower lips were measured and compared before and after treatment. Hard tissues were measured using posteroanterior cephalograms. Paired t test and correlation coefficients were calculated. RESULTS: Fourteen patients (4 men [28.5%] and 10 women [71.5%]; mean age, 29 yr) were included. Meaningful changes were observed in distance and angle measurements of the lips from before to after treatment. In area measurement, ratios of the area on the deviated side to that on the contralateral side for the upper and lower lips changed markedly and were close to 1.0 compared with before treatment. A relevant correlation was found between change in Me deviation and change in ratio of the height of the labial commissure. CONCLUSION: In cases of facial asymmetry caused by deviation of the maxilla and mandible, lip asymmetry can be adequately corrected by leveling the canted occlusal plane and positioning the Me toward the midline with 2-jaw surgery.

Possible alternative treatment for mandibular asymmetry by local unilateral IGF-1 injection into the mandibular condylar cavity: Experimental study in mice.

INTRODUCTION: The purpose of this study was to investigate whether a local unilateral IGF-1 injection into the mandibular condylar cavity can induce unilateral endochondral mandibular growth without any systemic adverse effects. METHODS: Seventy-five 3-week-old male Jcl:ICR mice were used in this study. The mice were divided into 2 groups: control group (n = 22) and IGF-1 group (n = 53). In the IGF-1 group, human IGF-1 was injected into the right mandibular condylar cavity, and phosphate-buffered saline solution was injected into the left cavity, 3 times per week for 10 weeks. RESULTS: There was no significant difference in body weight, serum human IGF-1 concentration, and soft tissue thickness of the cheeks including the masseter muscles between the 2 groups. Unilateral IGF-1 injection induced a lateral shift of the mandible to the contralateral side, and microcomputed tomogtraphy analysis showed that unilateral IGF-1 injection induced endochondral growth in the condyle. Col2, Ihh, and Runx2 were extensively upregulated by the local unilateral IGF-1 injection in real-time reverse transcription polymerase chain reaction analysis. Proliferation marker KI67, IGF-1 signaling molecule AKT1, and chondrogenic differentiation marker Col2 were strongly expressed in the IGF-1 injected condyle by immunohistochemistry. Vital labeling showed that the distance between the labels was increased in the IGF-1 injection group compared with that of the control group. CONCLUSIONS: The results verified in this study indicated that local unilateral IGF-1 injection into the mandibular condylar cavity successfully induced unilateral endochondral mandibular growth in mice without any systemic adverse effects. Thus, local unilateral IGF-1 injection into the mandibular condylar cavity could be a useful alternative for mandibular asymmetry therapy during the growth period. However, additional experimental and clinical studies will be necessary to prove the real effect of this new therapy.

A New Approach to Maxillary Protrusion with an Unstable Mandibular Position Accompanied with Unidentified Complaints: Case Report.

This case report describes the importance of combining morphological and functional examination with psychological examination in the establishment ofstable mandibular position in the treatment of maxillary protrusion with unstable mandibular position accompanied by unidentified complaints, which ensures safe orthodontic treatment.

Defining the location of the dental midline is critical for oral esthetics in camouflage orthodontic treatment of facial asymmetry.

When considering camouflage orthodontic treatment of a malocclusion associated with significant facial asymmetry, it is important to define the location of the dental midline. The patient, a 19-year-old Japanese woman, had an anterior open bite and a dental midline discrepancy associated with facial asymmetry. A nonsurgical treatment plan was considered. The main treatment objective was to correct the anterior open bite and the dental midlines in both arches. The dental midline discrepancy was eliminated, and proper overjet and overbite were achieved. Although the facial asymmetry remained, oral esthetics dramatically improved and a favorable occlusion was obtained. The results suggest that appropriately defining the location of the dental midline is critical for successful camouflage treatment of facial asymmetry.

Coordinated expression of H3K9 histone methyltransferases during tooth development in mice.

Tissue-specific gene expression is subjected to epigenetic and genetic regulation. Posttranslational modifications of histone tails alter the accessibility of nuclear proteins to DNA, thus affecting the activity of the regulatory complex of nuclear proteins. Methylation at histone 3 lysine 9 (H3K9) is a crucial modification that affects gene expression and cell differentiation. H3K9 is known to have 0-3 methylation states, and these four methylated states are determined by the expression of sets of histone methyltransferases. During development, teeth are formed through mutual interactions between the mesenchyme and epithelium via a process that is subjected to the epigenetic regulation. In this study, we examined the expression of all H3K9 methyltransferases (H3K9MTases) during mouse tooth development. We found that four H3K9MTases-G9a, Glp, Prdm2, and Suv39h1-were highly expressed in the tooth germ, with expression peaks at around embryonic days 16.5 and 17.5 in mice. Immunohistochemical and in situ hybridization analyses revealed that all four H3K9MTases were enriched in the mesenchyme more than in the epithelium. Substrates of H3K9MTases, H3K9me1, H3K9me2, and H3K9me3 were also enriched in the mesenchyme. Taken together, these data suggested that coordinated expression of four H3K9MTases in the dental mesenchyme might play important roles in tooth development.

Orthodontic Treatment of an Adult Class III Malocclusion with Severe Transverse Dental Compensation by Remaining of Buccal Crossbite.

UNLABELLED: This case report describes the importance of preventing more excessive transverse dental compensation during orthodontic treatment for a patient with severe transverse skeletal discrepancy. SUMMARY: The patient, a 33-years-old Japanese woman, had severe transverse skeletal discrepancy involving the maxilla and mandible. In addition, she had an extreme transverse dental compensation of the posterior teeth in mandibular arch (i.e. excessive lingual inclination of mandibular molars). AIM: Therefore, the main treatment objectives were to prevent more excessive transverse dental compensation by orthodontic treatment and improve the occlusal function. METHOD: We chose non-surgical orthodontic treatment. Because this patient did not think that the esthetic improvement with surgery would be worth the risk. RESULT: The orthodontic treatment resulted in sufficient elimination of the transverse dental compensation and movement of the teeth into their proper position where basal bone firmly support them. Anterior crossbite was corrected with remaining buccal crossbite, facial profile was improved and functional occlusion was obtained. At 2 years 2 months after the orthodontic treatment, the facial profile and occlusion remained favorable. CONCLUSION: This report would become an alternative to ideal treatment for a case with transverse skeletal discrepancy.

Cranial-base morphology in adults with skeletal Class III malocclusion.

INTRODUCTION: The objectives of this study were to clarify the characteristics of cranial-base morphology in adults with skeletal Class III malocclusion and investigate factors relating to the establishment of a skeletal Class III malocclusion. METHODS: Initial lateral cephalograms of women were examined. Subjects with an ANB angle of 0° to 4°, normal overjet and overbite, and a Class I molar relationship were classified as Class I (n = 86). Those with an ANB angle less than -1°, a Wits appraisal less than 2 mm, a negative overjet, and a Class III molar relationship were the Class III group (n = 86) in this study. Angular, linear, and coordinate measurements were made. Multivariate analysis of variance and the Student t test were used to analyze significant differences between the 2 groups. Discriminant analysis, logistic regression analysis, and decision analysis were used to identify which cranial-base and maxillomandibular variables influenced the establishment of a skeletal Class III malocclusion. RESULTS: The Class III group had smaller values for NSBa, SeSBa, FH-SSe, and FH-SBa. Sphenoidale and basion were more inferior and anterior than those of the Class I group. There was no difference in the anterior and posterior cranial-base lengths between the groups. Greater mandibular length was the first major characteristic in the Class III group, followed by smaller values for SeSBa and NSBa. CONCLUSIONS: Cranial-base morphology in adults with a skeletal Class III malocclusion is different from that in a skeletal Class I malocclusion. Smaller cranial-base angles, steeper posterior cranial bases, more inferiorly positioned sphenoidale, and more anteriorly positioned basion are major characteristics of skeletal Class III malocclusions. These characteristics play important roles in the establishment of a skeletal Class III malocclusion.

LRP1-deficient leptin receptor-positive cells in periodontal ligament tissue reduce alveolar bone mass by inhibiting bone formation.

OBJECTIVE: Leptin receptor-positive (LepR+) periodontal ligament (PDL) cells play a crucial role in osteogenesis during tooth socket healing and orthodontic tooth movement; however, the factors regulating osteoblast differentiation remain unclear. This study aimed to demonstrate the function of low-density lipoprotein receptor-related protein 1 (LRP1) in alveolar bone formation by examining conditional knockout (cKO) mice lacking LRP1 in LepR+ cells. DESIGN: Bone mass and formation were examined via bone morphometric analysis. Bone formation and resorption activities were determined via histochemical staining. Additionally, PDL cells collected from molars were induced to differentiate into osteoblasts with the addition of BMP2 and to mineralize with the addition of osteogenic medium. Osteoblast differentiation of PDL cells was examined by measuring the expression of osteoblast markers. RESULTS: Bone morphometry analysis revealed decreased mineral apposition rate and alveolar bone mass in cKO mice. Additionally, cKO mice showed a decreased number of osterix-positive cells in the PDL. cKO mice had a large number of osteoclasts around the alveolar bone near the root apex and mesial surface of the tooth. In the PDL cells from cKO mice, inhibition of mineralized matrix formation and decreased expression of alkaline phosphatase, osterix, bone sialoprotein, and osteocalcin were observed even when BMP2 was added to the medium. BMP2, BMP4, and osteoprotegerin expression also decreased, but RANKL expression increased dominantly. CONCLUSION: LRP1 in LepR+ cells promotes bone formation by stimulating osteoblast differentiation. Our findings can contribute to clinical research on bone diseases and help elucidate bone metabolism in the periodontal tissue.

Effects of chronic Akt/mTOR inhibition by rapamycin on mechanical overload-induced hypertrophy and myosin heavy chain transition in masseter muscle.

To examine the effects of the Akt/mammalian target of rapamycin (mTOR) pathway on masseter muscle hypertrophy and myosin heavy chain (MHC) transition in response to mechanical overload, we analyzed the effects of bite-opening (BO) on the hypertrophy and MHC composition of masseter muscle of BO-rats treated or not treated with rapamycin (RAPA), a selective mTOR inhibitor. The masseter muscle weight in BO-rats was significantly greater than that in controls, and this increase was attenuated by RAPA treatment. Expression of slow-twitch MHC isoforms was significantly increased in BO-rats with/without RAPA treatment, compared with controls, but the magnitude of the increase was much smaller in RAPA-treated BO-rats. Phosphorylation of p44/42 MAPK (ERK1/2), which preserves fast-twitch MHC isoforms in skeletal muscle, was significantly decreased in BO-rats, but the decrease was abrogated by RAPA treatment. Calcineurin signaling is known to be important for masseter muscle hypertrophy and fast-to-slow MHC isoform transition, but expression of known calcineurin activity modulators was unaffected by RAPA treatment. Taken together, these results indicate that the Akt/mTOR pathway is involved in both development of masseter muscle hypertrophy and fast-to-slow MHC isoform transition in response to mechanical overload with inhibition of the ERK1/2 pathway and operates independently of the calcineurin pathway.

Reconstruction of a collapsed dental arch in a patient with severe periodontitis.

This case report describes the significance of orthodontic treatment in reconstruction of a collapsed dental arch and a malocclusion associated with severe periodontitis. A Japanese man (age, 40 years 7 months) had an anterior crossbite, a collapsed occlusion, and severe periodontitis. Orthodontic treatment included the following steps: (1) correction of the anterior crossbite, labial movement of the maxillary incisors, and intrusion and retraction of the mandibular incisors; (2) correction of the posterior crossbite on the left side, buccal movement of the maxillary left canine and first premolars, and intrusion and retraction of the mandibular first premolar into the space of the mandibular left canine; (3) correction of the crowding of the mandibular right buccal segment and alignment of the teeth after extraction of the mandibular right first molar with a periapical lesion; and (4) improvement of the occlusion, with reconstruction of an acceptable occlusion. When combined with restorative and prosthodontic treatment, a fairly good occlusion was obtained. Reevaluation of the treatment after 11 years showed that the occlusion and periodontal condition were maintained well without deepening of the pockets and further bone loss. Orthodontic treatment with a systematic approach helped to recover the occlusion and prevented the recurrence of periodontitis by acquiring a good oral environment and motivating the patient to maintain oral health.

Interdisciplinary treatment of an adult with complete bilateral cleft lip and palate.

Interdisciplinary treatment was used for an adult patient born with complete bilateral cleft lip and palate. He had a severe maxillary deficiency with a wide cleft involving the alveolar and maxillary bone and palate. Reconstruction of the arches and occlusion in patients who missed the optimal treatment time is a difficult task for orthodontists. The clinical examination showed severe hypogenesis of the maxillary bone with a total crossbite. The maxillary dental arch was extremely narrow, and the maxillary incisors showed extensive caries caused by improper oral hygiene. Fixed and removable expansion appliances were used to improve the lateral crossbite. Alveolar bone grafting and unilateral LeFort I maxillary osteotomy were performed on the right side for alignment of the maxillary arch. Mandibular setback with bilateral sagittal split ramus osteotomy was also performed to correct the anteroposterior skeletal discrepancy. After postsurgical orthodontic treatment, prosthetic treatment was carried out for final reconstruction of esthetics and orthognathic function. Interdisciplinary treatment was necessary for this patient to achieve a proper occlusion and better esthetics.

Mechanism of active eruption of molars in adolescent rats.

The mechanism of active eruption of molars was examined in 36 male adolescent Wistar rats. Histological, histochemical [tetracycline (TC) labelling and alkaline phosphatase (ALP) activity], and immunohistochemical [transforming growth factor (TGF)-ß1, -ß2, and -ß3] investigations were conducted of the rat molar areas. Real-time reverse transcription-polymerase chain reaction (RT-PCR) for mRNA of TGF-ß was performed on the periodontal ligament (PDL) dissected out by laser capture microdissection. TC labelling lines showed that a considerable amount of bone formation occurred in the alveolar crest region, apical region, and intraradicular septum, indicating that the maxillary molars had moved downward. However, the periodontal fibres revealed a regular arrangement (alveolar crest, horizontal and oblique fibres) during the experimental period. This suggests that new formation of alveolar crest fibres and rearrangement of the periodontal fibres occurred in the PDL. ALP activity was intense on the bone surface and in the PDL. TGF-ß1 was also detected in osteoblasts and fibroblasts but less so in cementoblasts. Real-time RT-PCR also demonstrated significant expression of mRNA of TGF-ß1 in the PDL, indicating that TGF-ß1 was involved in active eruption. These results suggest that active eruption occurs in adolescent rats and can be managed by TGF-ß1.

Influence of pre-drilling diameter on the stability of orthodontic anchoring screws in the mid-palatal area.

PURPOSE: The aim of this study was to investigate the stability of orthodontic anchor screws (OASs) in the mid-palatal area according to pre-drilling diameter. METHODS: The success rate of 161 OASs (83 patients, φ2.0 mm, 6.0 mm in length) placed in a corresponding area to the mesial and distal borders of the first molar (mesial zone and distal zone) was assessed according to placement location and pre-drilling diameter (1.2 and 1.5 mm). Placement torque values from 73 OASs with a pre-drilling diameter of 1.2 mm were compared between success and failure groups. RESULTS: The success rates of OASs pre-drilled with φ1.2 and 1.5 mm were 94.5% and 83.0%, respectively (P < 0.05); corresponding rates in the mesial zone were 100.0% and 77.3% (P < 0.005), and those in the distal zone were 89.2% and 88.6%, respectively. Placement torques of OASs predrilled with φ1.2 mm in the success and failure groups were 25.9 and 19.2 N·cm, respectively (P < 0.05). CONCLUSION: A smaller pre-drilling diameter was associated with a higher success rate of OASs in the mid-palatal area, especially in the mesial zone. When pre-drilling diameter of 1.2 mm was used for φ2.0 mm OAS, greater placement torque was indicative of greater OAS stability.

Plaque-removal effect of ultrafine bubble water: Oral application in patients undergoing orthodontic treatment.

During orthodontic treatment, plaque tends to form around fixed orthodontic appliances, which increases the risk of dental caries. It has been reported that ultarafine bubble with a diameter <1 µm water (UFBW) effectively removes organic matter. In addition, UFBW is harmless and stable for at least one month with refrigeration. The aim of this study was to examine the plaque-removal effect of ultrafine bubble water (UFBW) to establish a new method to prevent dental caries in patients during orthodontic treatment procedures. The in vitro study examined different concentrations of UFBW and compared the cleaning effect to that of existing mouthwashes. High-concentration UFBW (HUFBW) was most effective in cleaning. In the subsequent clinical study, HUFBW showed a significantly higher plaque-removal effect compared to distilled water (p<0.01). Thus, supplementary use of HUFBW could decrease the incidence of dental caries during orthodontic treatment.

HSPA1A is upregulated in periodontal ligament at early stage of tooth movement in rats.

Heat shock proteins (HSPs) are molecular chaperones that maintain intracellular protein homeostasis and ensure survival of cells. Continuous orthodontic force on the tooth is considered to be a type of physical stress loaded to the periodontal ligament (PDL). However, little is known about the role of HSPs during tooth movement. This study was performed to examine the expression of HSPs in the PDL during tooth movement using laser microdissection, microarray analysis, real-time RT-PCR and immunohistochemistry. Gene expression of HSPA1A in the pressure zone of the PDL was higher during 6 h of tooth movement than in the control group. Expression of HSPA1A decreased with time. HSPA1A was also detected in the pressure zone of the PDL at the protein level 24 h after the initial tissue change. These results strongly suggest that expression of HSPA1A in the PDL during early stages of tooth movement is a critical factor for tissue reaction.

Elimination of transverse dental compensation is critical for treatment of patients with severe facial asymmetry.

This case report describes the importance of eliminating transverse dental compensation during preoperative orthodontic treatment for a patient with severe facial asymmetry. The patient, a 17-year-old Japanese woman, had severe facial asymmetry involving the maxilla and the mandible, and extreme transverse dental compensation of the anterior and posterior teeth in both arches. Therefore, the main treatment objectives were elimination of the transverse dental compensation by orthodontic treatment and correction of the morphology of the maxilla and the mandible by orthognathic surgery. The preoperative orthodontic treatment resulted in sufficient elimination of the transverse dental compensation and movement of the teeth into their proper positions so that basal bone firmly supported them. LeFort I osteotomy and sagittal split ramus osteotomy were performed to correct the skeletal morphology. Facial asymmetry was dramatically improved, and a favorable occlusion was obtained. At 1 year 8 months after the surgical orthodontic treatment, the facial symmetry and occlusion remained favorable. The results suggest that sufficient elimination of transverse dental compensation in the maxillary and mandibular arches during preoperative orthodontic treatment is requisite for successful treatment of severe facial asymmetry.