A comparison of maxillary posterior changes following facemask therapy: Skeletal anchorage versus tooth-borne anchorage.

OBJECTIVE: To compare changes in the maxillary posterior structure as seen in cone-beam computed tomography (CBCT) images resulting from facemask therapy using skeletal (miniplate/FM) anchorage versus tooth-borne anchorage (RME/FM). MATERIALS AND METHODS: A retrospective study was conducted on 20 patients divided into the miniplate/FM group (nine patients aged 9.5 ± 1.4 years) and the RME/FM group (11 patients aged 9.2 ± 1.4 years). CBCT images before and after facemask therapy were evaluated to assess changes in the maxillary posterior structure. RESULTS: The miniplate/FM group had greater advancement of the maxilla and midface compared to the RME/FM group (p < .05). Specifically, there was about three times more advancement of the pterygomaxillary suture in the miniplate/FM group than in the RME/FM group (p < .05). Moreover, the advancement of the pterygomaxillary suture was about half the advancement of A point in the miniplate/FM group, while only about 25% in the RME/FM group. Finally, the miniplate/FM group showed an increase in the transverse dimension of the posterior and superior parts of the maxilla (p < .05). CONCLUSION: There was greater forward movement of the pterygomaxillary suture with facemask therapy using the skeletal anchorage compared to tooth-borne anchorage, leading to a more significant advancement of the maxilla and midface.

Crown-root angulations of the maxillary anterior teeth according to malocclusions: A cone-beam computed tomography study in Korean population.

Objective: To compare crown-root angulations of the permanent maxillary anterior teeth in skeletal Class I, Class II, and Class III Korean malocclusion patients using cone-bean computed tomography (CBCT) images. Methods: Sixty CBCT images were collected from orthodontic patients archive based on skeletal Class I (0˚< A point-nasion-B point angle [ANB] < 4˚), Class II (ANB ≥ 4˚), and Class III (ANB ≤ 0˚) to have 20 samples in each group. Mesiodistal crown-root angulation (MDCRA) and labiolingual crown-root angulation (LLCRA) were evaluated after orientation of images. Crown-root angulations were compared among Class I, Class II, and Class III groups and among the maxillary anterior teeth in each group. Results: LLCRAs of the maxillary central incisor and the lateral incisor were significantly lower in Class III group than those in Class I group. However, those of the canine showed no significant differences among groups. MDCRAs of the maxillary anterior teeth did not significantly differ among groups either. Conclusions: Our results suggest that skeletal Class III malocclusion might affect LLCRA of the maxillary incisors, especially the central incisor.

Camouflage treatment by backward rotation of the mandible for a severe skeletal Class III malocclusion with aplastic anemia: A case report.

Orthognathic surgery is the primary treatment option for severe skeletal discrepancy. However, orthodontic camouflage should be considered as an alternative treatment option, considering the risks of surgery. A 19.5-year-old man presented with a severe prognathic mandible with a Class III molar relationship and an anterior crossbite. Orthognathic surgery could be considered because of his severe skeletal discrepancy and mandibular prognathism. However, the anesthetist for orthognathic surgery did not recommend surgery under general anesthesia because of risk factors associated with the patient's aplastic anemia, including bleeding and infections. Thus, a camouflage treatment to promote backward rotation of the mandible via orthodontic extrusion of the posterior teeth was planned. An anterior bite plate, intermaxillary elastics, and fixed orthodontic appliances were used to extrude the posterior teeth and to align the dentition. After 17 months of nonsurgical orthodontic treatment, normal occlusion was achieved, and the facial profile was dramatically improved. This case report describes the dentoskeletal and soft-tissue effects of mandibular rotation and its long-term stability.

Comparison of facemask therapy effects using skeletal and tooth-borne anchorage.

OBJECTIVES: To investigate long-term outcomes of dentoskeletal changes induced by facemask therapy using skeletal anchorage in Class III patients and compare them to those of conventional tooth-borne anchorage. MATERIALS AND METHODS: This retrospective study included 20 patients who received facemask (FM) therapy with miniplates as anchorage for maxillary protraction (Miniplate/FM group, 10.6 ± 1.1 years old [mean ± SD]) and 23 patients who were treated with facemask with rapid maxillary expander (RME/FM group, 10.0 ± 1.5 years old [mean ± SD]). Dentoskeletal changes were evaluated using lateral cephalograms at pretreatment (T1), after facemask therapy (T2), and at the post-pubertal stage (T3). Cephalometric changes were compared between groups and clinical success rates at T3 were evaluated. RESULTS: SNA and A to N perpendicular to FH increased significantly more in the Miniplate/FM group than in the RME/FM group when comparing short-term effects of facemask therapy (T1-T2). ANB, Wits appraisal, Angle of convexity, mandibular plane angle, and overjet decreased significantly more in the RME/FM group than in the Miniplate/FM group after facemask therapy (T2-T3). A more favorable intermaxillary relationship was observed in the Miniplate/FM group than in the RME/FM group in long-term observations (T1-T3). Clinical success rate at T3 was 95% in the Miniplate/FM group and 85% in the RME/FM group. CONCLUSIONS: Facemask therapy with skeletal anchorage showed a greater advancement of the maxilla and more favorable stability for correction of Class III malocclusion in the long-term than conventional facemask therapy with tooth-borne anchorage.

Facemask therapy with skeletal anchorage: A possible alternative to orthognathic surgery.

Treatment of skeletal Class III malocclusion in young patients is very challenging. Facemask therapy has been proven to be effective in early correction of Class III malocclusion. With the aid of skeletal anchorage, the orthopaedic effects are expected to be greater than the effects with conventional facemask with tooth-borne anchorage. However, only a few studies have reported on the long-term stability of facemask therapy combined with skeletal anchorage. This report examines two patients with skeletal Class III malocclusion who were treated with facemask and skeletal anchorage followed by orthodontic treatment using fixed orthodontic appliances. The long-term effects of facemask therapy with skeletal anchorage are discussed and compared with the conventional facemask therapy.

Application of the foramina of the trigeminal nerve as landmarks for analysis of craniofacial morphology.

OBJECTIVE: The objective of this study was to develop new parameters based on the foramina of the trigeminal nerve and to compare them with the conventional cephalometric parameters in different facial skeletal types. METHODS: Cone-beam computed tomography (CBCT) scans and cephalograms from 147 adult patients (57 males and 90 females; mean age, 26.1 years) were categorized as Class I (1° < ANB < 3°), Class II (ANB > 5°), and Class III (ANB < -1°). Seven foramina in the craniofacial area-foramen rotundum (Rot), foramen ovale (Ov), infraorbital foramen, greater palatine foramen, incisive foramen (IF), mandibular foramen (MDF), and mental foramen (MTF)-were identified in the CBCT images. Various linear, angular, and ratio parameters were compared between the groups by using the foramina, and the relationship between the new parameters and the conventional cephalometric parameters was assessed. RESULTS: The distances between the foramina in the cranial base did not differ among the three groups. However, the Rot-IF length was shorter in female Class III patients, while the Ov-MTF length, MDF-MTF length, and Ov-MDF length were shorter in Class II patients than in Class III patients of both sexes. The MDF-MTF/FH plane angle was larger in Class II patients than in Class III patients of both sexes. Most parameters showed moderate to high correlations, but the Ov-MDF-MTF angle showed a relatively low correlation with the gonial angle. CONCLUSIONS: The foramina of the trigeminal nerve can be used to supplement assessments based on the conventional skeletal landmarks on CBCT images.

Botulinum Toxin Injection to Treat Masticatory Movement Disorder Corrected Mandibular Asymmetry in a Growing Patient.

An 8-year-old girl with masticatory movement disorder received botulinum toxin-A (BTX-A) injection and orthodontic treatment. She showed facial asymmetry with right masseter muscle hyperplasia. After BTX-A injection combined with orthodontic treatment, the transverse discrepancy between right and left maxillary dentition completely corrected. Cone-beam computed tomography images revealed that the height of the left mandibular ramus had increased by 2.3 mm, considerably more than on the right side, the discrepancy in mandibular ramus height between the left and the right decreased dramatically. In a short period, BTX-A injection combined with orthodontic treatment corrected a mandibular movement disorder with asymmetric mandibular growth in a growing patient.

Botulinum toxin-A injection into the anterior belly of the digastric muscle for the prevention of post-operative open bite in class II malocclusions: a case report and literature review.

BACKGROUND: Class II malocclusion patients with hyperdivergent facial types are characterized by short mandibular body lengths and anterior open bite. Accordingly, the treatment for hyperdivergent skeletal class II malocclusion is a lengthening of the mandibular body length and a counterclockwise rotation of the mandible. To prevent post-operative relapse, botulinum toxin-A (BTX-A) injection can be a retention modality. CASE PRESENTATION: A class II open-bite patient received BTX-A injection to the anterior belly of her digastric muscle for the prevention of post-operative relapse. The relapse was evaluated via a clinical examination and a lateral cephalometric radiograph after the completion of post-surgical orthodontic treatment. The patient showed stable occlusion without any signs of relapse at 15 months post-operatively. CONCLUSION: In this case presentation, a single injection into the anterior belly of the digastric muscle was sufficient for the prevention of post-operative open bite.

Time and pattern of the fusion of the spheno-occipital synchondrosis in patients with skeletal Class I and Class III malocclusion.

OBJECTIVES: To investigate the time and pattern of fusion of the spheno-occipital synchondrosis in patients with skeletal Class I and Class III malocclusion using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: A total of 262 CBCT images were collected: 140 skeletal Class I (0° < ANB < 4°; 71 males, 69 females) and 122 skeletal Class III (ANB ≤ 0°; 61 males and 61 females). The fusion stages were identified using CBCT images of a six-stage system defined by the appearance of osseous cores and ossifying vestige in the synchondrosis. The age distributions of each stage and the pattern of fusion were evaluated. RESULTS: The stages of fusion progressed with increasing age (P < .05, r = .824), and the age distributions in the female groups were generally 1 to 3 years younger than those in the male groups. However, no significant differences were observed between the skeletal Class I and Class III groups regarding the time of ossification of the synchondrosis. The osseous cores appeared most frequently in the supero-center part, followed by the mid-center part of the synchondrosis. CONCLUSIONS: The time and pattern of fusion of the spheno-occipital synchondrosis are not apparently different between patients with Class I malocclusion and those with Class III malocclusion. The osseous cores appear frequently in the supero-center and mid-center of the synchondrosis with various patterns before the end of the pubertal growth spurt period.

Application of Enamel Matrix Derivative and Intrusive Orthodontic Movement in the Treatment of Vertical Bony Defects: A Case Report.

This case report presents treatment of a severe localized horizontal bone loss combined with infrabony defects adjacent to pathologically migrated teeth by orthodontic intrusion following a graft of enamel matrix derivative (EMD) without root surface conditioning. The patient was diagnosed with Angle Class II malocclusion, anterior spacing, and pathologically migrated incisors. Graft of EMD mixed with bone materials was applied for periodontal regeneration before orthodontic treatment, and periapical radiographs were taken every 3 months for radiographic evaluation. After closure of anterior spaces by orthodontic treatment, infrabony defects improved dramatically, with a favorable alveolar bone level and periodontal pocket depth.

Pierre Robin sequence with severe scoliosis in an adult: A case report of clinical and radiological features.

Pierre Robin sequence (PRS) is characterized by the triad of micrognathia, glossoptosis, and airway obstruction. PRS does not have a single pathogenesis, but rather is associated with multiple syndromes. This report presents the case of a 35-year-old woman with PRS and scoliosis. Among the syndromes related to PRS, cerebro-costo-mandibular syndrome (CCMS), which is characterized by posterior rib gap defects and vertebral anomalies, was suspected in this patient. However, no posterior rib gap defect was detected on radiological examinations. Although over 80 cases of CCMS have been reported to date, few cases of PRS with scoliosis alone have been reported. Therefore, this report demonstrated the clinical, radiological, and cephalometric characteristics of an adult patient with PRS and scoliosis, but without rib anomalies.

Aberrant growth of the anterior cranial base relevant to severe midface hypoplasia of Apert syndrome.

BACKGROUND: A 9-year-old male showed severe defects in midface structures, which resulted in maxillary hypoplasia, ocular hypertelorism, relative mandibular prognathism, and syndactyly. He had been diagnosed as having Apert syndrome and received a surgery of frontal calvaria distraction osteotomy to treat the steep forehead at 6 months old, and a surgery of digital separation to treat severe syndactyly of both hands at 6 years old. Nevertheless, he still showed a turribrachycephalic cranial profile with proptosis, a horizontal groove above supraorbital ridge, and a short nose with bulbous tip. METHODS: Fundamental aberrant growth may be associated with the cranial base structure in radiological observation. RESULTS: The Apert syndrome patient had a shorter and thinner nasal septum in panthomogram, PA view, and Waters' view; shorter zygomatico-maxillary width (83.5 mm) in Waters' view; shorter length between the sella and nasion (63.7 mm) on cephalogram; and bigger zygomatic axis angle of the cranial base (118.2°) in basal cranial view than a normal 9-year-old male (94.8 mm, 72.5 mm, 98.1°, respectively). On the other hand, the Apert syndrome patient showed interdigitating calcification of coronal suture similar to that of a normal 30-year-old male in a skull PA view. CONCLUSION: Taken together, the Apert syndrome patient, 9 years old, showed retarded growth of the anterior cranial base affecting severe midface hypoplasia, which resulted in a hypoplastic nasal septum axis, retruded zygomatic axes, and retarded growth of the maxilla and palate even after frontal calvaria distraction osteotomy 8 years ago. Therefore, it was suggested that the severe midface hypoplasia and dysostotic facial profile of the present Apert syndrome case are closely relevant to the aberrant growth of the anterior cranial base supporting the whole oro-facial and forebrain development.

Clinical application of an intraoral scanner for serial evaluation of orthodontic tooth movement: A preliminary study.

The aim of this study was to test the clinical application of an intraoral scanner for serial evaluation of orthodontic tooth movement. The maxillary dentitions of eight patients with fixed orthodontic appliances were scanned using an intraoral scanner at the beginning of treatment (T0), and at 1 month (T1), 2 months (T2), 3 months (T3), and 4 months (T4) after T0. The serial digital models were superimposed on the palatal surface as a reference area, and the linear and angular changes of the central incisors, canines, and first molars were evaluated. The intraclass correlation coefficient and method errors showed that this method was clinically acceptable. Various types of orthodontic tooth movements, including minute movements, could be observed every month. The intraoral scanner and digital superimposition technique enabled the serial evaluation of orthodontic tooth movement without taking serial impressions and/or acquiring radiographs.

Quantitative comparison of incisal tooth wear in patients receiving one-phase or two-phase treatment for skeletal Class III malocclusion with anterior crossbite.

OBJECTIVES: The present study aimed to compare the amount of incisal tooth wear in the maxillary central incisors of patients with skeletal Class III malocclusion and anterior crossbite receiving one-phase or two-phase treatment. The hypothesis was that tooth wear would differ according to treatment modalities. MATERIALS AND METHODS: Maxillary dental casts obtained before (T1) and after (T2) orthodontic treatment were divided into three groups. Group I consisted of casts from 21 patients (7 males, 14 females; mean age 9.8 years) who received two-phase treatment (maxillary protraction followed by fixed appliance therapy). Group II comprised casts from 37 patients who underwent orthodontic camouflage treatment for crossbite, subdivided according to age. Group IIa consisted of casts from 15 adolescents (8 males, 7 females; mean age 13.5 years), and group IIb consisted of casts from 22 adults (13 males, 9 females; mean age 24.5 years). Maxillary dental casts obtained at T1 and T2 were scanned. For each pair of digital images, T2 was superimposed on T1 using the best-fit method. Tooth wear was quantified and compared among groups. RESULTS: Significantly less tooth wear was observed in group I compared to groups IIa and IIb, but no difference was found between groups IIa and IIb. Spearman correlation analysis revealed no significant correlation between tooth wear and age, treatment duration, or craniofacial morphology. CONCLUSIONS: Despite the long duration of early treatment, it caused less wear of the maxillary central incisors than did orthodontic camouflage treatment.

Effect of drug-loaded TiO2 nanotube arrays on osseointegration in an orthodontic miniscrew: an in-vivo pilot study.

Osseointegration was evaluated for the surface of miniscrews with TiO2 nanotube arrays containing drugs in this in-vivo study. The diameter and length of the TiO2 nanotube arrays were about 70 nm and 5 µm, respectively. Recombinant human bone morphogenetic protein-2 (rhBMP-2) or ibuprofen was loaded in the TiO2 nanotube arrays with 12 miniscrews. The 12 drug-loaded miniscrews, 6 miniscrews with no drug-loaded TiO2 nanotube arrays and 6 conventional miniscrews, were placed on the tibias of New Zealand white rabbits. Histological osseointegration was assessed 8 weeks after implantation by measuring the bone-to-implant contact (BIC) ratio. Ibuprofen-loaded miniscrews showed a significantly higher BIC of 71.6% over conventional miniscrews of 44.3% on average. The mean BIC ratios of rhBMP-2-loaded miniscrews and no drug-loaded miniscrews was 24.6% and 60.1%, respectively. Our results suggest that TiO2 nanotube arrays on the surface of miniscrews could be used as carriers of drugs, and loading ibuprofen in TiO2 nanotube arrays may improve osseointegration of miniscrews. However, the effect of rhBMP-2 loaded in TiO2 nanotube arrays on osseointegration of miniscrews was questionable in this pilot study.

The genial tubercle: A prospective novel landmark for the diagnosis of mandibular asymmetry.

INTRODUCTION: Identifying menton (Me) on posteroanterior cephalograms and three-dimensional (3D) cone-beam computed tomography (CBCT) images is difficult, because the midpoint of the symphyseal area is not identifiable after the mandibular symphysis fuses at an early age. The aim of this study was to evaluate the reliability of the identification of the genial tubercle (GT) in patients with mandibular asymmetry and to compare it with that of the traditional landmark, Me. METHODS: The samples comprised 20 CBCT images of adults with mandibular asymmetry. Two examiners performed the identifications and measurements. Me and GT were marked, and the anteroposterior, vertical, and transverse distances to the three reference planes were measured on 3D-reconstructed CBCT images. The intra- and inter-examiner reliability of landmark identification of Me and GT were assessed using the intraclass correlation coefficient (ICC) and Bland-Altman plots. RESULTS: The Me and GT landmarks showed excellent reliability (ICC ≥ 0.993) three-dimensionally. In the transverse evaluation, the ICC values of the GT (range, 0.997-0.999) tended to be slightly higher than those of Me (range, 0.993-0.996). In the Bland-Altman plots for the two separate assessments, Me showed a maximum error of 1.76 mm in the transverse direction, whereas the GT showed a maximum error of 0.96 mm in the 95% limit. CONCLUSIONS: Our results suggest that both Me and GT are clinically reliable and equally useful landmarks for the evaluation of mandibular asymmetry on CBCT images.

Orthodontic tunnel miniscrews with and without TiO2 nanotube arrays as a drug-delivery system: In vivo study.

Orthodontic tunnel miniscrews with and without TiO2 nanotube arrays were fabricated to improve the induction of new bone formation and osseointegration. To inject the drug of recombinant human bone morphogenetic protein, tunnels in a conventional machined miniscrew were machined by a computer-numerical-control lathe. TiO2 nanotube arrays to load the drug were also formed on the surface of the tunnel miniscrew by anodic oxidation. To obtain clean TiO2 nanotube arrays, two-step anodic oxidation was conducted. The diameters of TiO2 nanotube window and TiO2 nanotube were ∼70 nm and ∼110 nm, respectively. Three groups, i.e., a conventional machined miniscrew, a tunnel miniscrew without TiO2 nanotube arrays, and a tunnel miniscrew with TiO2 nanotube arrays, were prepared and inserted in the legs of five New Zealand White rabbits. In a histomorphometric analysis, the bone implant contact ratios of the tunnel miniscrews with the TiO2 nanotube arrays and without the TiO2 nanotube arrays were 5.84% and 5.88%, respectively. These values were higher than the value of 4.30% for the conventional machined miniscrew. The bone surface ratios in the tunnel miniscrew with and without the TiO2 nanotube were also higher than those of the conventional machined miniscrew. The measured values of the tunnel miniscrew with and without the nanotube and the conventional miniscrew were 76.75%, 73.41%, and 44.82%, respectively, although the differences were statistically insignificant. New bone at three weeks and six weeks after the operations were found in the tunnel miniscrews in fluorescent images. Both the tunnel miniscrews with and without the TiO2 nanotube arrays demonstrated greater bone formation compared to the conventional miniscrews. However, TiO2 nanotube arrays was not likely to provide additional benefit to the tunnel miniscrew. An in vivo study suggested that the tunnel fabricated in the miniscrew can be efficient drug-delivery systems to improve osseointegration.

Identification of a stable reference area for superimposing mandibular digital models.

PURPOSE: The purpose of this retrospective study was to assess the stability of buccal and lingual alveolar bone surfaces for superimposing three-dimensional (3D) digital models of dental casts. MATERIALS AND METHODS: The pre- and posttreatment dental casts and lateral cephalometric radiographs were obtained from 10 adult patients who had undergone orthodontic treatment entailing the extraction of four premolars. Five of them had bilateral mandibular tori and the other 5 patients had no torus. Dental casts were scanned with a three-dimensional (3D) surface scanning system and 3D digital models were reconstructed using 3D reverse modeling software. The pre- and posttreatment digital models were superimposed on the following reference areas by the best-fit method: Area 1, bilateral lingual surfaces of the alveolar process of the posterior teeth; Area 2, the lingual alveolar surface of the anterior and posterior teeth; Area 3, bilateral surfaces of the posterior teeth's buccal and lingual alveolar surfaces; Area 4, bilateral mandibular tori. The horizontal and vertical movements of the mandibular central incisors and first molars were measured on cephalometric radiographs and on the 3D digital models. RESULTS: In the 5 patients without a mandibular torus, the median differences between cephalograms and 3D digital models ranged from 0.8-1.9 mm and the maximum differences from 1.5-10.0 mm. The median and maximum differences between cephalograms and 3D digital models superimposed on Area 2 were greater than those superimposed on Areas 1 and 3. In the patients with mandibular tori, the median differences between cephalograms and 3D digital models were under 1.0 mm, the maximum difference being 0.7 mm. CONCLUSION: The buccal and lingual alveolar surface near the dentition seems to be inappropriate as a reference area for superimposing 3D mandibular digital models of patients without a mandibular torus. Mandibular tori in adult patients are stable structures which can be used as reference areas for the superimposition of 3D mandibular digital models.

Effect of TiO2 nanotubes arrays on osseointegration of orthodontic miniscrew.

To increase the stability of orthodontic miniscrews, TiO2 nanotube arrays were fabricated on the surface of Ti miniscrews and the effect of those arrays on the osseointegration of miniscrews was evaluated. Highly ordered TiO2 nanotube arrays were grown on the surface of orthodontic miniscrews. Ethylene glycol based electrolyte was used in the anodic oxidation process. Two-step anodic oxidation was conducted to obtain clean and open windows in TiO2 nanotube arrays. The diameter and length of the TiO2 nanotube arrays were ~ 70 nm and ~ 5 µm, respectively. The miniscrews with TiO2 nanotube arrays were implanted in the legs of New Zealand white rabbits for 8 weeks. Histological osseointegration was assessed by bone-to-implant contact ratio, and three-dimensional bone volume ratio was measured by micro-computed tomography analysis. The miniscrews with TiO2 nanotube arrays had a greater mean bone-to-implant contact ratio of 52.8 % than the control, 29.3 %. Mean bone volume ratio (BV/TV) was also higher in the miniscrews with TiO2 nanotube arrays, at 81.2 % than those in the control via micro-CT analysis. Our findings support that TiO2 nanotube arrays on the surface of miniscrews enhance osseointegration and improve the stability of the miniscrew.

Changes in natural head position after orthognathic surgery in skeletal Class III patients.

INTRODUCTION: The purpose of this study was to evaluate the change in natural head position (NHP) after orthognathic surgery in skeletal Class III patients. METHODS: We used pretreatment (T1) and posttreatment (T2) cephalometric radiographs and T1 and T2 lateral facial photographs of 20 skeletal Class III patients (mean age, 21.6 years), with 20 skeletal Class I patients (mean age, 22.2 years) as the controls. The Class III patients had undergone mandibular setback surgery, and the patients in the control group had received conventional orthodontic treatment. All lateral facial photographs were recorded in NHP. The true vertical line (TVL) was transferred from the photograph to the cephalometric radiograph, and then the angle between the TVL and the Frankfort horizontal plane (TVL/FH) was measured. A t test and a paired t test were used to verify the differences between the 2 groups, and between the T1 and T2 measurements in each group. RESULTS: The mean TVL/FH at T1 was significantly greater in the Class III group than in the Class I group; this indicated that the Class III group showed head flexion. However, the mean TVL/FH of the Class III group decreased by -3.1° at T2; this indicated head extension, and it did not significantly differ from that of the Class I group. Nineteen of the 20 Class I patients showed minimal or no change in their TVL/FH (-1.5° to 1.5°) at T2. On the other hand, 6 of the 20 Class III patients showed more than a 4.5° decrease in their TVL/FH at T2. CONCLUSIONS: Most of the Class I patients showed minimal or no change in their NHP at T2, but some Class III patients had changes in their NHP that tended toward head extension after mandibular setback surgery. Thus, soft tissue analysis using the TVL in NHP may not be reliable for some skeletal Class III patients who undergo mandibular setback surgery.