Comparison of the skeletal stability after mandibular counter-clockwise rotation in three surgical procedures.

The treatment of mandibular deformities with an anterior open bite is challenging. In this study, skeletal stability after mandibular osteotomies was evaluated to determine the best treatment for mandibular prognathism with an anterior open bite in three procedures: intraoral vertical ramus osteotomy (IVRO), conventional sagittal split ramus osteotomy (conv-SSRO), and SSRO without bone fixation (nonfix-SSRO). Patients who underwent mandibular osteotomy to correct skeletal mandibular protrusion were included. Changes in skeletal and soft tissues were assessed using lateral cephalograms taken before (T1), 3 ± 2 days (T2), and 12 ± 3 months (T3) after surgery. Thirty-nine patients were included: nine in the IVRO group and 11 and 19 in the conv- and nonfix-SSRO groups, respectively. The mandibular plane angles (MPAs) of the T2-T1 were - 2.7 ± 2.0 (p = 0.0040), - 3.7 ± 1.7 (p < 0.0001), and - 2.3 ± 0.7 (p < 0.0001) in the IVRO, conv-SSRO, and nonfix-SSRO groups, respectively. The skeletal relapse of the MPAs was not related to the MPA at T2-T1, and it was approximately 1.3° in the conv-SSRO group. The skeletal relapse of the MAPs was significantly correlated with the MPA of T2-T1 in the IVRO (p = 0.0402) and non-fix-SSRO (p = 0.0173) groups. When the relapse of the MPAs was less than 1.3°, the MPA of T2-T1 was calculated as 2.5° in the nonfix-SSRO group. When the MPA of T2-T1 is less than 2.5°, non-fix SSRO may produce a reliable outcome, and when it is more than 2.5°, conv-SSRO may produce better outcomes.

Three-dimensional analysis of mandible ramus morphology and transverse stability after intraoral vertical ramus osteotomy.

OBJECTIVES: The purpose of this study was to investigate short- and long-term postoperative changes of both morphology and transverse stability in mandibular ramus after intraoral vertical ramus osteotomy (IVRO) in patients with jaw deformity using three-dimensional (3D) orthognathic surgery planning treatment software for measurement of distances and angles. STUDY DESIGN: This retrospective study included consecutive patients with skeletal Class III malocclusion who had undergone intraoral vertical ramus osteotomy and computed tomography images before (T0), immediately after (T1), and 1 year after (T2) surgery. Reference points, reference lines and evaluation items were designated on the reconstructed 3D surface models to measure distances, angles and volume. The average values at T0, T1, T2 and time-dependent changes in variables were obtained. RESULTS: After surgery, the condylar length, ramal height, mandibular body length and mandibular ramus volume were significantly decreased (P < 0.01), while clinically insignificant change was observed from T1 to T2. The angular length was increased immediately after surgery (P < 0.05), but it was decreased 1 year after surgery (P < 0.05). Lateral ramal inclination showed significant increase after surgery (P < 0.05) and maintained at T2. CONCLUSION: Changes in the morphology of the mandibular ramus caused by IVRO do not obviously bring negative effect on facial appearance. Furthermore, despite position and angle of mandibular ramus changed after IVRO, good transverse stability was observed postoperatively. Therefore, IVRO technique can be safely used without compromising esthetic results.

Sexual dimorphism and geographical variance: their impact on the reliability of the antilingula as a landmark in human mandibular surgery.

The intraoral vertical ramus osteotomy (IVRO) is an orthognathic procedure that is used to correct dentofacial abnormalities, and is performed by approaching the lateral aspect of the mandibular ramus. This approach, however, precludes visualisation of the inferior alveolar nerve (IAN) on the medial side, thereby placing it at risk of iatrogenic damage. The antilingula, a bony prominence on the lateral mandibular ramus, has been proposed as a landmark for prediction of the IAN's location during IVRO. The current study aimed to evaluate the variation in incidence and position of the antilingula, and therefore to determine its suitability as a surgical landmark during IVRO. The study included 480 dry hemimandibles from eight geographical populations from the Duckworth Collection in Cambridge. Skulls were sexed by visual analysis of dimorphic traits. Positional relations were determined through the digitisation of nine anatomical landmarks. The antilingula was identified in all specimens. No significant difference was identified in the positional relation between the antilingula and mandibular foramen between sexes, but multiple differences were identified in this relation between geographical populations. Our data showed that, irrespective of geographical variation, an osteotomy performed 8mm posterior to the antilingula would avoid the mandibular foramen in 98.8% of cases.

The three-dimensional evaluation of positional change in mandibular condyle after intraoral vertical ramus osteotomy.

OBJECTIVES: The purpose of this study was to compare the changes of the condylar axis, the anteroposterior condylar position relative to the glenoid fossa, after intraoral vertical ramus osteotomy (IVRO). STUDY DESIGN: 21 patients diagnosed as skeletal class III malocclusion underwent IVRO and were followed according to the authors' postoperative management regimen. The three-dimensional positions of the condyles were evaluated by cone-beam computerized tomography (CBCT) at pre-op, post-op, and at follow-up. CBCT images were referenced to assess the condylar axis change and the anteroposterior condylar position in the glenoid fossa. A repeated-measures analysis of variance (P<0.05) also was performed. RESULTS: After surgery, both the axial condylar angles and the anteroposterior condylar position were significantly different (P<0.05). The coronal condylar axis rotated outwardly. The anteroposterior condylar position in the glenoid fossa had moved from the concentric to the anterior position. But the condyle changes between post-op and follow-up (P>0.05) were insignificant. CONCLUSIONS: With postoperative intermaxillary elastic traction, the condyles changed their positions physiologically for newly established jaw movement after IVRO.

The correlation between surgical reference points: antilingula, lingula, and mandibular foramen.

The purpose of the present study was to investigate and determine the anatomical relationship between the antilingula, lingula, and mandibular foramen using cone-beam computed tomography (CBCT). METHODS: CBCT images of 90 participants (180 mandibular ramus) were collected. The locations of and distances between the antilingula, lingual, and mandibular foramen according to side (right and left) and skeletal patterns were measured and then evaluated by statistical analysis. RESULTS: Only 27 participants (15%) had bilateral distinct antilingula, lingula, and mandibular foramen. The antilingula was located anteriorly (4.28 mm and 3.59 mm) and above (1.99 mm and 8.52 mm) the lingula and mandibular foramen. The lingula was behind (0.69 mm) and above (6.53 mm) the mandibular foramen. Skeletal Class III was anterior and inferior to Class II and Class I in the antilingula, lingula, and mandibular foramen. Considering the correlations of landmarks, we found that the lingula was strongly correlated with the mandibular foramen on the X axis (r = 0.757) and Y-axis (r = 0.878). CONCLUSION: The antilingula is located anteriorly and above the lingula and mandibular foramen. The lingula is behind and above the mandibular foramen. The osteotomy line of orthognathic surgery can only be safely designed through actual measurement of the locations of the antilingula, lingula, and mandibular foramen.

The presence probability of mandibular lingla and antilingula.

PURPOSE: The lingula and antilingula are crucial surgical landmarks for mandibular setback surgery. The purpose of study was to investigate the correlation of presence probability between lingual and antilingula. MATERIALS AND METHODS: A total of 180 cone-beam computed tomography sides were collected from 90 patients. The probability of absence of the lingula and antilingula was recorded with respect to the gender, mandible (unilateral and bilateral), and skeletal patterns (Class I, II, III); in addition, the correlations between these variables were analysed. RESULTS: Of the 180 sides, 9 sides showed the absence of the lingula (5%) and 34 sides showed the absence of the antilingula (18.9%). Pearson's test revealed that the presence of the lingula and antilingula differed nonsignificantly with respect to gender and skeletal patterns, respectively. The bilateral presence of the lingula was observed in 16 sides (91.1%), and that of the antilingula was observed in 122 sides (67.8%). Pearson's test verified a significant correlation between the presence of the left and right lingula (P<0.05). By contrast, gender and skeletal patterns were nonsignificantly correlated with the presence of the lingula and antilingula. The presence of the lingula was also nonsignificantly correlated with that of the antilingula. CONCLUSION: Gender and skeletal patterns were nonsignificantly correlated with the presence of the lingula and antilingula, respectively. The presence of the lingula was also nonsignificantly correlated with that of the antilingula. Consequently, lingula and antilingula cannot serve as the absolute standards for mandibular setback surgery.

The Direction of Double-Jaw Surgery Relapse for Correction of Skeletal Class III Deformity: Bilateral Sagittal Split Versus Intraoral Vertical Ramus Setback Osteotomies.

OBJECTIVES: This prospective comparative clinical trial study aims to investigate the postoperative stability of the double-jaw surgical treatment of skeletal Class III deformity and to compare two different mandibular surgical approaches. The study goal is to locate the relapsing direction of both the maxilla and the distal segment after either bilateral sagittal split ramus osteotomy (BSSO), or intraoral vertical ramus osteotomy (IVRO). METHODS: Twenty-two (22) patients with skeletal Class III were included in this study. The patients were treated with double-jaw surgery by LeFort I osteotomy combined with either BSSO or IVRO. Lateral cephalograms taken before (T0), immediately after (T1), and 1 year after the surgery (T2) were studied and analyzed. RESULT: The mean mandibular setback and maxillary advancement in the BSSO group were 6.22 mm at B Point and 2.93 mm at A point with relapse percentages of 24.9 and 26.6%, respectively, while the mean mandibular setback and maxillary advancement in the IVRO group were 2.55 mm at B point and 5.89 mm at A point with relapse percentages of 22.1 and 23.5%, respectively. The magnitude of the setback significantly accounted for the relapse. CONCLUSION: One-year follow-up revealed that the maxilla would be displaced posteriorly and inferiorly in both groups. Regarding the direction of the mandibular relapse, the mandible in BSSO surgical group was displaced forward and upward, while in IVRO surgical group, the directions were completely different in which the mandible is displaced backward and downward.

Patient satisfaction and oral health-related quality of life 10-15 years after orthodontic-surgical treatment of mandibular prognathism.

This study investigated 36 patients at 10-15 years after they had undergone mandibular setback surgery by intraoral vertical ramus osteotomy (IVRO) and subsequent intermaxillary fixation for 6 weeks. The patients completed a 37-item structured questionnaire to evaluate patient satisfaction and possible long-term effects of the treatment. Visual analogue scales were used to measure self-perceived changes in seven items concerning oral function and appearance. Oral health-related quality of life was assessed using the Oral Impacts on Daily Performance (OIDP) index. The main reasons for seeking treatment were to improve chewing function and appearance. The treatment had resulted in significant improvements regarding chewing function, appearance, bullying, and self-confidence in social settings (all P<0.05). All patients were either very satisfied (61%) or reasonably satisfied (39%) with the treatment result. The mean OIDP frequency score was 8.49 on a scale from 8 to 40. Seventy-four percent of the patients reported no oral impacts on quality of life. In conclusion, 10-15 years after combined orthodontic and IVRO surgical treatment of mandibular prognathism, the patients were satisfied, and oral health-related quality of life was reported to be good.

The different effects of intraoral vertical ramus osteotomy (IVRO) and sagittal split ramus osteotomy (SSRO) on mandibular border movement.

OBJECTIVES: This study investigated the different effects of intraoral vertical ramus osteotomy (IVRO) and sagittal split ramus osteotomy (SSRO) on mandibular border movement. METHODS: The participants included 22 patients receiving IVRO and 22 patients receiving SSRO who were treated at Okayama University Hospital. Their mandibular border movement was evaluated in three dimensions with 6° of freedom using an optical recording system. RESULTS: A strong correlation between condylar and lower incisor movement was observed during maximum jaw protrusion and laterotrusion. Significant improvements in condylar and lower incisor movement were detected after orthognathic surgery during maximum jaw protrusion and laterotrusion in the IVRO group and during maximum jaw protrusion in the SSRO group. DISCUSSION: IVRO likely achieves greater improvement in jaw movement than SSRO. Therefore, the application of IVRO could be considered in the treatment of patients with jaw deformities featuring temporomandibular joint problems.

Skeletal and dental stability after intraoral vertical ramus osteotomy: a long-term follow-up.

The purpose of this study was to elucidate the long-term skeletal and dental stability after combined orthodontic and orthognathic surgical treatment of mandibular prognathism with the intraoral vertical ramus osteotomy (IVRO) as the surgical technique followed by 6 weeks of intermaxillary fixation (IMF). Thirty-six patients were included in the study. Mean age at surgery was 21.6 years. Lateral cephalograms and study casts obtained before the start of treatment (T0), and 8 weeks (T1), 1 year (T2), and 12.5 years (T3) after the operation were evaluated. Mean mandibular setback measured at point B was 8.3mm. Between T1 and T2, a mean anterior relapse of 12% of the setback was observed. Between T2 and T3, the anterior relapse persisted, but decreased to 7% of the setback measured at point B. Despite dental adjustments in both jaws, a statistically significant reduction in overjet was observed during both observation periods. However, the change of the mandible in an anterior direction was small and of minor clinical importance for most of the patients. In conclusion these results indicate that combined orthodontic and orthognathic surgical treatment of mandibular prognathism with the IVRO as the surgical procedure followed by 6 weeks of IMF provides predictable and good long-term clinical results.

Long-term changes in mandibular and facial widths after mandibular setback surgery using intraoral vertical ramus osteotomy.

This study was performed to evaluate the long-term changes in mandibular width, lower facial width, and ramus angulation after intraoral vertical ramus osteotomy (IVRO) and to identify the factors influencing these changes. This retrospective study included 53 consecutive patients with mandibular prognathism who underwent IVRO with (n=33) or without (n=20) Le Fort I osteotomy. Postero-anterior cephalograms and frontal facial photographs obtained before, 1 month after, and at least 24 months after IVRO were used for measurements. A linear mixed model and paired t-tests were used to analyze temporal changes and the associated influencing factors. The mandibular width increased immediately after surgery (P<0.05), but decreased continuously thereafter. The ramus angulation showed negligible change within the first month (P>0.05) and decreased thereafter up to approximately 36 months. The amounts of mandibular setback and posterior impaction and the length of time postoperative influenced these changes. The lower facial width changed, although inconsistently, within 3mm over time (P>0.05). In conclusion, the mandibular width increased after IVRO but seemed to normalize within approximately 3 years. The lower facial width did not reflect underlying skeletal changes. Therefore, long-term transverse changes after IVRO can be considered clinically irrelevant.

Variation of plate fixation for mandibular advancement with intraoral vertical ramus osteotomy using endoscopically assisted intraoral rigid or semi-rigid internal fixation: Case series study: Postoperative condylar seating control for mandibular advancement.

The purpose of the present study was to evaluate the safety and efficacy associated with mandibular advancement by intraoral vertical ramus osteotomy (IVRO) with endoscopically assisted intraoral rigid or semi-rigid internal fixation. The study sample included all patients who had undergone an mandibular advancement by IVRO procedure with endoscopically assisted intraoral plate fixation from September 2008 to May 2012. An mandibular advancement by IVRO with endoscopically assisted intraoral rigid or semi-rigid internal fixation was used for mandibular advancement. The patients were analyzed prospectively, with more than 2 years of follow-up, and were evaluated in terms of functional results, postoperative complications, and skeletal stability. A total of 14 patients (bilateral, 7 patients with class II; unilateral, 7 patients with asymmetry) were included in the present study. The average degree of mandibular advancement was 5.5 ± 1.9 mm (range, 3-9 mm). Both the occlusal relationship and facial appearance in all patients were significantly improved by the surgical-orthodontic treatment, with no major harmful clinical symptoms. In addition, one-screw semi-rigid fixation could control postoperative passive condylar seating. This study showed that mandibular advancement by IVRO with endoscopically assisted, intraoral semi-rigid internal fixation offers a promising treatment alternative for patients with skeletal class II malocclusion or facial asymmetry.

Impact on the pharyngeal airway space of different orthognathic procedures for the prognathic mandible.

The study objective was to evaluate, through a meta-analysis, the impact on the pharyngeal airway space (PAS) of different orthognathic surgeries for the treatment of the prognathic mandible. An electronic search of three databases and hand searches were carried out up to December 2014. The inclusion criteria were clinical human studies, including randomized controlled trials (RCTs), controlled clinical trials (CCTs), and retrospective studies, with the aim of comparing bilateral sagittal split osteotomy (BSSO) to intraoral vertical ramus osteotomy (IVRO), or one-jaw to two-jaw surgery for the treatment of the prognathic mandible. The PAS changes (anterior-posterior dimensions and cross-sectional area) at the level of the nasopharynx, oropharynx, and hypopharynx were analyzed. A statistically significant difference was found between BSSO and IVRO groups and one-jaw surgery and two-jaw surgery with regard to PAS changes after the treatment of mandibular prognathism. The results of this meta-analysis indicate that BSSO presents less change in the PAS after mandibular setback surgery compared to IVRO. Furthermore, the results of this study suggest that bimaxillary surgery is superior to mandibular setback surgery alone for the correction of the prognathic mandible, particularly in patients with factors predisposing them to the development of breathing problems.

Two-year follow-up of changes in bite force and occlusal contact area after intraoral vertical ramus osteotomy with and without Le Fort I osteotomy.

This study was performed to examine the longitudinal changes in bite force and occlusal contact area after mandibular setback surgery via intraoral vertical ramus osteotomy (IVRO). Patients with mandibular prognathism who underwent IVRO (surgical group: 39 men and 39 women) were compared with subjects with class I skeletal and dental relationships (control group; 32 men and 35 women). The surgical group was divided into two subgroups: 1-jaw surgery (n = 30) and 2-jaw surgery (n = 48). Bite force and contact area were measured in maximum intercuspation with the Dental Prescale System before treatment, within 1 month before surgery, and at 1, 3, 6, 9, 12, and 24 months postsurgery. A linear mixed model was used to investigate the time-dependent changes and associated factors. Bite force and contact area decreased during presurgical orthodontic treatment, were minimal at 1 month postsurgery, and increased gradually thereafter. The 1-jaw and 2-jaw subgroups showed no significant differences in bite force. The time-dependent changes in bite force were significantly different according to the contact area (P < 0.05). The results of this study suggest that bite force and occlusal contact area gradually increase throughout the postsurgical evaluation period. Increasing the occlusal contact area may be essential for improving bite force after surgery.

Skeletal Relapse After Mandibular Setback in Bi Max Surgery: Intraoral Vertical Ramus versus Bilateral Sagittal Split Osteotomies.

OBJECTIVES: This study aimed to measure and compare the postoperative horizontal and vertical changes (relapse) that occur at B point and pogonion after intraoral vertical ramus osteotomy (IVRO) without fixation and bilateral sagittal split osteotomy (BSSO) with semi rigid internal fixation in bimax surgery. MATERIALS AND METHODS: Eleven patients with skeletal class III malocclusion mandibular prognathism and maxillary hypoplasia were chosen. Six cases underwent BSSO; and five IVRO. All patients underwent Lefort I osteotomy without genioplasty. RESULT: Postoperative changes (relapse) of B-point and pogonion in horizontal and vertical axes from 1 week post operatively (T0) to 1 year post operatively (T2) were assessed and the percentage of relapse of each point and each axis was compared. It was noted that the horizontal relapse in IVRO was 27.7 % at B point and 40.6 % at pogonion while, in BSSO group it was noted that the horizontal relapse was 28.1 % at B point and a greater number i.e., 40.9 % at pogonion. CONCLUSION: The percentage of horizontal relapse after IVRO without fixation is equal to that after BSSO with semi rigid internal fixation.

Remodelling pattern of the ramus on submentovertex cephalographs after intraoral vertical ramus osteotomy.

The aim of this study was to evaluate postoperative changes in proximal segments and condyles on the transverse plane after intraoral vertical ramus osteotomy. This is a retrospective study that included 200 subjects operated on, from 2003 to 2010, from whom we compared preoperative and postoperative (7 days, and 1, 3, 6, and 12 months) submentovertex radiographs. Postoperative positional changes in the condyles showed a mean (SD) of 15.05 (8.97)° lateral rotation, which slowly returned towards the original position. However, 4.53 (6.03)° lateral rotation remained on the postoperative radiographs at 1 year. There were no remarkable differences in intercondylar distance at any given time interval, which showed pure rotation of condyles without any bodily shift. The length of horizontal overlapping was also increased after operation, and was later decreased by 48% on postoperative radiographs at 1 year through the remodelling process. Condyles had rotated laterally without a lateral shifting movement only after intraoral vertical ramus osteotomy. Further studies to evaluate the physiological effects of rotational movement of the condyles after the operation in patients with symptoms in the temporomandibular joint are indicated.

Assessment of skeletal stability of intraoral vertical ramus osteotomy with one-day maxillary-mandibular fixation followed by early jaw exercise.

PURPOSE: Intraoral vertical ramus osteotomy (IVRO) is an effective surgical technique for cases of mandibular setback, is simpler and has a lower incidence of mental paraesthesia when compared to sagittal split ramus osteotomy (SSRO). However, IVRO has a disadvantage in the prolonged duration of postoperative maxillary-mandibular fixation (MMF) required due to the absence of rigid bone fixation. To avoid an extended MMF period, we developed a postoperative management protocol for our IVRO patients, using jaw exercises with elastic bands starting on the second day after surgery. METHODS: We evaluated the cephalometric skeletal and dental stabilities of 16 IVRO patients as they followed our protocol. RESULTS: The stabilities were confirmed and were similar to those of previous reports. CONCLUSION: One-day MMF and early initiation of jaw exercise after IVRO did not affect the jaw position stability. Moreover, our findings suggest that starting jaw exercise earlier after IVRO surgery is beneficial, as it allows patients to avoid a long period of rigid MMF so that they can resume their normal daily activities sooner.

The use of distraction osteogenesis to treat hemifacial microsomia: a case report

Distraction osteogenesis (DO) is a surgical method of bone formation that involves an osteotomy and sequential stretching of the healing callus by gradual movement and subsequent remodeling. DO is used to correct facial asymmetry, such as in patients with hemifacial microsomia, maxillary or mandibular retrusion, cleft lip and palate, alveolar defects, and craniofacial deficiency. It is accomplished with the aid of a distraction device, which is secured with screws placed directly into bone, for a predetermined length of time. Hemifacial microsomia is characterized by unilateral facial hypoplasia, often with unilateral shortening of the mandible and subsequent malocclusion. Patients with hemifacial microsomia and facial asymmetry have a vertically short maxilla, tilted occlusal plane, and short mandible. Early treatment is necessary to avoid subsequent impaired midfacial growth. The standard treatment of these malformations consists of the application of bone grafts, which can lead to unpredictable growth. The new bone-lengthening procedure represents a limited surgical intervention and opens up a new perspective for treatment, especially in younger children with severe deformities. This report describes a case of hemifacial microsomia (Type-II left-sided hemifacial microsomia). The patient, a 10-year-old child, visited our clinic for facial asymmetry correction. He had a hypoplastic mandible, displaced ear lobe, 10 mm canting on the right side, and malocclusion. We planned DO to lengthen the left mandible in conjunction with a Le Fort I osteotomy for decanting and then perform a right intraoral vertical ramus osteotomy (IVRO). Progressive distraction at a rate of 0.5 mm/12 hours was initiated 7 days postoperatively. The duration of DO was 17 days. The consolidation period was 3 months. Satisfactory results were obtained in our case, indicating that DO can be used successfully for functional, aesthetic reconstruction of the mandible. We report a case involving DO in conjunction with orthognathic surgery for correcting mandibular hypoplasia with a review of the literature.

A study on the prediction of orthognathic surgery using rapid prototyping model technology