Changes in Tongue Area, Pharyngeal Area, and Pharyngeal Airway Velocity after Correction of Mandibular Prognathism.

This study aimed to investigate the correlation between the amount of mandibular setback, and the related changes of the tongue area, pharyngeal area, and pharyngeal airflow velocity. Twenty-five patients treated for mandibular prognathism, and serial cephalograms were obtained (T1: preoperation, T2: more than one year postoperation). The postoperative area of the tongue, pharyngeal airway space, and pharyngeal airflow velocity were investigated. Statistical analysis was performed with the Student t-test and Pearson correlation. The amount of mandible setback was significant after surgery (12.8 mm; p < 0.001). The pharyngeal area was significantly reduced 115.5 mm2 (p = 0.046). There was a slight reduction of the tongue area (43.2 mm2; p = 0.305) and an increase of pharyngeal airflow velocity (0.3 m/s; p = 0.133). The Pearson correlation coefficient test showed no statistical significance among the amount of horizontal setback and vertical movement of the mandible, such as the reductions in the tongue area, the pharyngeal airway space, and the increase in pharyngeal airflow velocity. Larger amounts of mandibular setback caused a significant reduction of pharyngeal airway area, but without significant changes of the tongue area and pharyngeal airflow velocity.

Changes in Pharyngeal Airway Space and Craniocervical Angle after Anterior Bimaxillary Subapical Osteotomy.

PURPOSE: This study explored the effects of genioplasty (Gep) and anterior subapical osteotomy of the maxilla and mandible (ASOMx+ASOMd) on the pharyngeal airway dimensions of patients with bimaxillary protrusion (BiP). METHOD: Thirty-two patients were divided into 2 groups. Group 1 received ASOMx+ASOMd, and group 2 received ASOMx+ASOMd+Gep. The cephalograms of the patients were collected before surgery and 2 months after surgery. Changes in the landmarks, related cephalometric angles (gonial, SN-GoGn, Y-axis, and SN-C2C4 angles), and 2 pharyngeal airway dimensions (uvulo-pharyngeal airway [UOP] and tongue-pharyngeal airway [TOP]) were analyzed. RESULTS: Before surgery, the parameters (incisor superius, incisor inferius, menton, most superior and anterior point of the hyoid bone, tip of the uvula, inferoanterior point on the second cervical vertebra, and inferoanterior point on the fourth cervical vertebra) and measured angles (SNA, SNB, ANB, gonial, SN-GoGn, Y-axis, and C4C2-SN) of both groups showed no significant differences. Following ASOMx, the patients in groups 1 and 2 exhibited a setback by 7.0 and 6.6 mm, respectively. After ASOMd, groups 1 and 2 exhibited 4.9 and 5.3 mm setbacks, respectively. No significant difference in the amount of setback was observed between groups 1 and 2. The postoperative horizontal and vertical positions of Me in group 2 were significantly forward by 6.1 mm and upward by 1.5 mm, respectively. Regarding pharyngeal airway dimensions, TOP was decreased in group 1 (1.7 mm) and group 2 (1.3 mm). In the postoperative Pearson correlation coefficient test, the horizontal and vertical positions of Me showed no significant correlation with TOP in both groups. Therefore, Gep did not prevent the reduction of TOP in group 2. CONCLUSION: After bimaxillary anterior subapical osteotomy, the TOP of patients with BiP was decreased, and this situation was unavoidable, regardless of whether Gep was performed.

Importance in the Occurrence Distribution of Minimum Oropharyngeal Cross-Sectional Area in the Different Skeletal Patterns Using Cone-Beam Computed Tomography.

PURPOSE: Obstructive sleep apnea is a condition involving repetitive partial or complete collapse of the pharyngeal airway, especially in patient with mandibular hypoplasia. The present study investigated the differences between the volume of the oropharyngeal airway and the minimum axial area in three skeletal patterns through the use of cone-beam computed tomography (CBCT). MATERIALS AND METHODS: CBCT scans of 147 patients were collected to measure the upper oropharyngeal airway volume (UOV), lower oropharyngeal airway volume (LOV), upper oropharyngeal airway area (UOA), minimum upper oropharyngeal airway area (MUOA), lower oropharyngeal airway area (LOA), minimum lower oropharyngeal airway area (MLOA), anatomical structures (orbitale, Or; porion, Po; pogonion, Pog; hyoid, H; second cervical vertebra, C2; fourth cervical vertebra, C4), and relevant angles. Statistical analysis was performed using analysis of variance and Pearson's test. RESULTS: Compared with patients in Class II, those in Class III and Class I exhibited a significantly anterior position of H and Pog. The vertical positions of H and Pog revealed no significant difference between the three skeletal patterns. Patients in skeletal Class III exhibited significantly larger oropharyngeal area (UOA, MUOA, LOA, MLOA) and oropharyngeal airway (UOV and LOV) than those in skeletal Class II did. The horizontal position of Pog had a moderately significant correlation with UOA (r = 0.471) and MUOA (r = 0.455). CONCLUSION: Patients in skeletal Class II had significantly smaller oropharyngeal airway areas and volumes than those in Class III did. The minimum oropharyngeal cross-sectional area had a 67% probability of occurrence in the upper oropharyngeal airway among patients in Class I and Class II and a 50% probability of occurrence among patients in Class III.

Evaluation of pharyngeal airway volume for different dentofacial skeletal patterns using cone-beam computed tomography.

BACKGROUND/PURPOSE: Understanding of the three-dimensional airway space in three skeletal patterns is important in orthodontic treatment. This study investigated differences between the volume of pharyngeal airway sections and the smallest cross-sectional area in three skeletal patterns by using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: The 90 patients were collected to measure total pharyngeal airway volume (TP), velopharyngeal airway volume (VP), glossopharyngeal airway volume (GP), oropharyngeal airway volume (OP), hypopharyngeal airway volume (HP), and the smallest cross-sectional areas (SCA) of the upper respiratory tract as well as other relevant anatomical structures. The mean values differences between classes were analyzed using ANOVA. Pearson's test was used to compare classes in terms of the correlations between different factors. RESULTS: Patients in skeletal classes I and III exhibited significantly higher SCA values (322.6 mm2and 344.5 mm2 respectively) than those in skeletal class II (240.8 mm2). Subjects from skeletal classes I and III exhibited significantly higher values of VP, HP, and OP than those in skeletal class II. Skeletal classes I and III exhibited significantly higher TP values (31190.1 mm3 and 30696.2 mm3, respectively) than those in skeletal class II (22386.0 mm3). Non-significant relationships were discovered between pharyngeal airway and skeletal pattern. Conversely, significant relationships were found between TP and gender, ANB, SNB, hyoid and pogonion positions. CONCLUSION: The skeletal class II has smaller airway volume than those in skeletal class I and III. The pharyngeal airway volumes could serve as a guide in differentiating the different skeletal classes in clinical settings.

Relationship between hyoid bone and pharyngeal airway in different skeletal patterns.

BACKGROUND/PURPOSE: The hyoid bone and its attached muscles play an important role in the maintenance of the pharyngeal airway space. The aim of the present study was to investigate the correlations between hyoid bone and pharyngeal airway spaces among three skeletal patterns. MATERIALS AND METHODS: Cephalograms of 90 male and 90 female were divided into skeletal patterns: Class I, Class II, and Class III. The following pharyngeal airway spaces were measured: SP, soft palate related pharyngeal airway; BP, B point related pharyngeal airway; C2P, second cervical vertebra related pharyngeal airway; and LP, laryngopharyngeal airway. The paired t-test, one-way analysis of variance, and Pearson correlation analysis were used in the statistical analyses. RESULTS: SP was significantly longer in Class III (12.4 mm) than in Class I (10.7 mm) and Class II (9.5 mm), and BP was significantly greater in Class III (16.3 mm) than in Class II (12.4 mm). The hyoid bone had a significantly anterior location in Class III compared to Class II, whereas vertical positions of the hyoid bone showed no significant differences among the three skeletal patterns. Among female with a Class III skeletal pattern, the horizontal position of the hyoid bone had a positive moderate, significant correlation with the C2P, whereas among male, this was not observed. CONCLUSION: The location of the maxilla (SNA) was not significantly correlated with the pharyngeal airway space. However, the more protruding the mandible (SNB) is, the more anterior the hyoid bone and the longer the pharyngeal airway will be.

Nasomaxillary and mandibular bone growth in primary school girls aged 7 to 12 years.

BACKGROUND/PURPOSE: Facial bone growth manifests in primary school-aged children, especially girls. This study investigated the changes in nasomaxillary and mandibular morphology of primary school girls. MATERIALS AND METHODS: Cephalograms of 60 primary school girls were divided into 3 groups (group I, aged 7-8 years; group II, aged 9-10 years; and group III, aged 11-12 years). The dimensions of the nasomaxilla (nasal bone length, nasal ridge length, nasal depth, palatal length, and maxillary height) and mandible (condylar length, condylar width, coronoid length, coronoid width, ramus length, body length, symphysis length, and entire mandibular length) were measured. One-way ANOVA and Pearson's correlation coefficient were used for statistical analysis. RESULTS: Nasal ridge length, nasal depth, and maxillary height were significantly greater in group III than in group I and group II. Condylar width and body length were significantly greater in group III than in group I and group II. Pearson's correlation revealed significant positive correlations between age and nasal ridge length, nasal depth, or maxillary height. There were also significant positive correlations between age and ramus length, body length, or entire length of the mandible. CONCLUSION: We found that nasal ridge length, nasal depth, maxillary height, condylar width and body length were significantly greater in group III than in group I or in group II. Moreover, there were significant correlations between age and the nasal ridge length, nasal depth, maxillary height, ramus length, body length, or entire length of the mandible.

Postoperative Skeletal Stability and Pharyngeal Airway: Counterclockwise versus Clockwise Rotation during Mandibular Setback Surgery.

PURPOSE: To compare the effects of counterclockwise rotation (CCR) and clockwise rotation (CR) of the mandible on the pharyngeal airway during mandibular setback surgery. Materials and Methods. Serial cephalograms of 40 patients with mandibular prognathism, including 20 who underwent CCR and 20 who underwent CR, were taken at the following time intervals: preoperatively (T1), immediately postoperatively (T2), >1 year after surgery (T3), final surgical changes (T31), postoperative stability (T32), and immediate surgical change (T21). Changes in menton (Me) and hyoid (H) positions, soft palate width, soft palate length, soft palate angle and craniovertebral angle (C2C4-SN), and pharyngeal airway spaces (nasal pharyngeal airway (NOP), uvula pharyngeal airway (UOP), tongue pharyngeal airway (TOP), and epiglottis pharyngeal airway (EOP)) were evaluated. RESULTS: The mean Me (T31) setback for CCR and CR was 12.56 and 13.06 mm, respectively, with 2.41 mm upward and 3.29 mm downward, respectively. The vertical Me position of CR exhibited significant downward movement compared with that of CCR. The mean H setback results for CCR and CR were 4.42 and 5.75 mm, respectively, with 1.47 mm downward and 2.97 mm downward, respectively. The C4C2-SN angles for CCR and CR increased by 2.68° and 3.65°, respectively, whereas their palatal angles increased by 2.35° and 5.25°, respectively. Pearson's correlation analysis (T31) revealed that for CCR, no pharyngeal airway spaces were significantly correlated with any measured variables. In CR, NOP was significantly correlated (r = 0.58) with the vertical Me position. Significant relapse (T32) was observed after CR in the horizontal (r = 0.58) with the vertical Me position. Significant relapse (T32) was observed after CR in the horizontal (r = 0.58) with the vertical Me position. Significant relapse (T32) was observed after CR in the horizontal (. CONCLUSION: Pharyngeal airway space narrowed postoperatively, and its patency was appropriately maintained through natural physiological regulation of the craniovertebral angle (C2C4-SN). Significant postoperative relapse was correlated with CR.

Recognizing the peak bone mass (age 30) as a cutoff point to achieve the success of orthodontic implants.

The aim of present study was to investigate the critical risk factor (age 30: peak bone mass) to evaluate the success of orthodontic implants. A total of 426 orthodontic implants were placed in 270 patients as orthodontic anchorages. Data were analyzed according to patient's characteristics, location of placement, implant categories, and orthodontic force. The young patients were the age ≤ 30 years and the older patients were the age > 30 years. Statistical analysis was performed and a p value < 0.05 was considered to indicate statistical significance. The Chi-square or Fisher exact test was used depending on sample sizes. The null hypothesis was no statistically significant correlation between age ≤ 30 years and age > 30 years. The overall success rate (with and without predrill) was 89.2%. The success rate of orthodontic implants was significantly larger in younger patients (89.9%) than in older patients (76.1%). Recognizing age-related factor in the success rates, older patient (> 30 years) were significant lower than young patients (≤ 30 years) in the gender (female and male), malocclusion (Class II), facial pattern (ortho and hyperdivergent), location (infrazygomatic crest), jaw (maxilla), side (right), material (titanium and stainless), length (9 mm and 10 mm), diameter (2 mm), load (< 3 weeks), and force (intrusion). Therefore, the null hypothesis was rejected. Age 30 is a cutoff point to achieve the success of orthodontic implants. The success rates of older patients (age > 30 years) were significant lower than young patients (age ≤ 30 years), especially in female.

Comparison of Pharyngeal Airway between Mandibular Setback Surgery Patients (Skeletal Class III) and Nonsurgery Patients (Skeletal Classes I and II).

PURPOSE: We investigated the pharyngeal airway dimensions and their correlations in patients who underwent mandibular setback surgery versus those who did not. MATERIALS AND METHODS: One hundred and sixty cephalometric radiographs (120 patients) were obtained from patients with three skeletal malocclusion classifications: Class I and Class II in the nonsurgery group and Class III in the surgery group (preoperative and postoperative cephalograms). The following dimensions were measured: nasopharyngeal airway (NOP), uvulopharyngeal airway (UOP), shortest distance from the posterior tongue to the pharyngeal wall (TOP), and distance from the epiglottis to the pharyngeal wall (EOP). Paired t test, one-way analysis of variance, and Pearson correlation coefficients were used for statistical analysis. RESULTS: Preoperatively, UOP and TOP of skeletal Class III patients (15.2 mm and 16.6 mm) were significantly larger than those of skeletal Class II (11.5 mm and 12 mm) and Class II (12.3 mm and 12.9 mm) patients, respectively. No differences were observed in EOP between the three skeletal patterns. The hyoid bone of Class III patients was significantly anterior to that of Class I/II patients. Furthermore, UOP had a moderate negative correlation with soft palate length. Postoperatively, no significant difference (UOP, TOP, EOP, soft palate width, and hyoid bone) was found between the skeletal classes. CONCLUSION: Preoperatively, UOP and TOP of skeletal Class III patients were significantly wider than those of skeletal Class I/II patients. Pre- and postoperatively, EOP did not exhibit significant differences among the three skeletal classifications. No differences were found in all postoperative pharyngeal airway dimensions between Class III patients and nonsurgery patients (Class I and Class II).

The Changes of Cheek Line (Lateral) and Face Line (Frontal) after Correction of Mandibular Prognathism.

OBJECTIVE: The purpose of the present study was to investigate the improvements of facial profile and postoperative stability by single mandibular setback surgery. MATERIALS AND METHODS: The study included twenty-seven patients who underwent mandibular prognathism correction by sagittal split ramus osteotomy (SSRO). Cephalometric radiograms (lateral and frontal) were collected and analyzed at three intervals: preoperatively (T1), immediately postoperatively (T2), and final follow-up postoperatively (T3). The lateral and frontal cephalometric parameters were measured. The immediate postoperative change (T21), postoperative stability (T32), and final surgical change (T31) were calculated and analyzed. The null hypothesis is that postoperative stability (T32) was not significantly correlated to amount of mandibular setback (T21). RESULTS: The immediate postoperative change (T21) of menton (Me) was significantly backward 8.7 mm. In the final postoperative change (T31), average chin points anterior movements were approximately 0.32 mm. Investigating frontal appearance, inter ramus posterior (InterRp) and intergonion (InterGo) widths were significantly increased with 1.8 and 2.2 mm, respectively. Bilateral ramus angles were not significantly increased, about 1°. The horizontal Me (T32) had significant correlation (p = 0.028) with amount of setback (T21). Therefore, null hypothesis is rejected. CONCLUSION: Postoperative relapse was significantly correlated to the amount of setback. The frontal transverse changes (InterRp and InterGo) were significantly increased.

Comparisons of Jaw Line and Face Line after Mandibular Setback: Intraoral Vertical Ramus versus Sagittal Split Ramus Osteotomies.

BACKGROUND: This study investigates the differences in the lateral profile and frontal appearance after sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO) procedures for the correction of mandibular prognathism. METHODS: Sixty patients (30 SSRO and 30 IVRO) underwent mandibular setback surgery. Serial cephalograms were obtained: (1) T1: approximately 1 month before surgery; (2) T2: at least 6 months after surgery for SSRO and at least 1 year after surgery for IVRO. The landmarks, linear distances, and related angles were measured. The t-test was applied to the intragroup and intergroup comparisons. The null hypothesis was that SSRO and IVRO made no difference in the facial appearance. RESULTS: In the IVRO group, the ramus and gonial widths significantly decreased by 3.9 mm and 5.8 mm, respectively. SSRO significantly reduced the gonial angle by 2.6°, and IVRO increased it significantly by 5.3°. The postoperative increases at frontal bone levels 0 and 1 after IVRO were significantly larger than those after SSRO, but, at level 3, the increases after SSRO were larger than those after IVRO. In the frontal muscular and facial planes, SSRO and IVRO presented no difference. The frontal jaw angle and face angle were significantly larger with IVRO than with SSRO. Therefore, the null hypothesis was rejected. CONCLUSIONS: The ramus width and gonial width were significantly decreased in IVRO compared to SSRO. IVRO increased angles in the lateral profile (gonial angle and mandibular plane angle) and frontal appearance (jaw angle and face angle) more than SSRO did.

Facial profile and frontal changes after bimaxillary surgery in patients with mandibular prognathism.

BACKGROUND/PURPOSE: Patients are always concerned about their postoperative appearance before surgery for facial deformity correction. The present study investigated the facial profile and frontal changes following two-jaw surgery. METHODS: Forty patients who underwent two-jaw surgery were divided by the amount of mandibular setback (group I: ≤8 mm and group II: >8 mm). Cephalometric radiograms (lateral and frontal) were collected and analyzed at three intervals: preoperatively (T1), immediately postoperatively (T2), and final follow-up (T3). The following points were identified: cheek points (C1-C5), pronasale (Prn, tip of the nose), anterior nasal spine (ANS), subnasal (Sn), point A, labrale superius (Ls), incision superius (Is), labrale inferius (Li), incision inferius (Ii), point B, labiomental sulcus (Si), pogonion (Pog), soft tissue pogonion (PogS), ramus point (RP), and gonion (Go). The immediate postoperative changes (T21), final postoperative changes (T32), and final stability (T31) were calculated and analyzed. RESULTS: In T31, the cheek line showed significant advancements of 2.3 mm (group I) and 1.6 mm (group II). The soft:hard tissue ratios were significantly correlated: Prn:ANS (0.37:1), Prn:A (0.39:1), Sn:A (0.85:1), C3:A (0.82:1), Ls:Is (0.92:1), Li:Ii (0.91:1), Si:B (0.88:1), and PogS:Pog (group I, 0.78:1 and group II, 0.93:1). The intercondylion and intergonial widths of group II (T31) significantly increased 1.8 and 4 mm, respectively. Regarding the postoperative skeletal stability (T32), group I showed significant correlations between amounts of mandibular setback, but group II did not. CONCLUSION: In the facial profile, the cheek line showed significant advancement postoperatively. The frontal mandibular transverse dimensions were significantly increased.

The Effect of Pterygomasseteric Sling's Area in the Postoperative Stability after Mandibular Setback Surgery.

PURPOSE: The purpose of the present study was to investigate the correlation between the postoperative stability and area of pterygomasseteric sling (PMS). MATERIALS AND METHODS: Forty patients of mandibular prognathism were treated by isolated mandibular setback. Serial lateral cephalograms were collected (preoperatively [T1], immediately after surgery [T2], and more than 1 year postoperatively [T3]). The postoperative stability (T32) was divided into 3 groups (total, forward, and backward movements). The areas of PMS, immediate surgical changes (T21), postoperative stability (T32), and final surgical change (T31) were analyzed by Student's t-test, Pearson's correlation coefficient, and multiple linear regression analysis. RESULTS: The amount of mean setback (T21) was 12.6 mm in total group, 13.8 mm in forward group, and 10.8 mm in backward group. In the total group, postoperative stability (T32) was 0.6 mm forward and reduction area of PMS (T31) was 291 mm2 (17.2%). The reduction area of PMS (T31) was 298.2 mm2 (18%) and 263.1 (15.3%) mm2 in the forward group (3 mm) and backward group (2.4 mm), respectively. However, reduction area of PMS (T31) showed weak correlation with postoperative stability (T32) in all groups. CONCLUSION: Total and forward groups presented significant correlations between postoperative stability (T32) and amount of setback (T21).

Palatal bone thickness and associated factors in adult miniscrew placements: A cone-beam computed tomography study.

Palatal bone thickness measurements obtained by cone-beam computed tomography (CBCT) in 30 men and 28 women were evaluated for associated factors. Palatal bone thickness was measured at 20 locations unilateral to the midpalatal suture and posterior to the incisive foramen. Tongue position, presence of posterior crossbite, and palatal morphology were recorded. Lateral cephalograms acquired from CBCT data were used to calculate Frankfort-mandibular plane angles (FMA). At almost all sites, bone thickness was greater in males than in females, but the difference was statistically significant at only seven sites. Bone thickness showed no associations with tongue position, palatal morphology, or presence of posterior crossbite. In women, FMA significantly correlated with bone thickness at 12 locations. In conclusion, palatal bone thickness is unassociated with tongue position, posterior crossbite, or palatal morphology. In hyperdivergent women, however, available bone may be smaller than normal in the middle and posterior palatal areas; in such cases, a shorter than normal miniscrew may be needed to avoid penetrating the nasal cavity.