Predisposing conditions for condylar sag after intraoral vertical ramus osteotomy.

Intraoral vertical ramus osteotomy (IVRO) is used to treat mandibular prognathism and temporomandibular disorders. However, the improvement of temporomandibular disorders after IVRO is considered to be due to the anterior and downward movement of the mandibular condyle, which may lead to condylar sag, and in the worst case, condylar luxation. In this retrospective cohort study, we examined factors potentially associated with condylar sag. Univariate analysis indicated that condylar sag was significantly associated with the following factors: magnitude of setback (P = 0.001), less than 3 mm setback (P < 0.001), presence of temporomandibular joint (TMJ) symptoms (P = 0.002), Wilkes classification (P = 0.039), occlusal cant correction ≥ 2 mm (P = 0.018), and mandibular condyle deformation (P < 0.001). Setback magnitude (P = 0.032) and TMJ symptoms (P = 0.007) remained significant in the multivariate analysis. In the receiver operating characteristic curve, the setback magnitude cut-off value for condylar sag after IVRO was 3.25 mm. Thus, the incidence of condylar sag after IVRO is increased with a smaller setback magnitude (≤ 3.25 mm) and the presence of TMJ symptoms. These factors should be evaluated by surgeons during treatment planning for IVRO to estimate condylar sag, and it may be possible to predict the risk of condylar luxation.

Computational analysis of airflow dynamics for predicting collapsible sites in the upper airways: a preliminary study.

The present study aimed to detail the relationship between the flow and structure characteristics of the upper airways and airway collapsibility in obstructive sleep apnea. Using a computational approach, we performed simulations of the flow and structure of the upper airways in two patients having different facial morphologies: retruding and protruding jaws, respectively. First, transient flow simulation was performed using a prescribed volume flow rate to observe flow characteristics within upper airways with an unsteady effect. In the retruding jaw, the maximum magnitude of velocity and pressure drop with velocity shear and vortical motion was observed at the oropharyngeal level. In contrast, in the protruding jaw, the overall magnitude of velocity and pressure was relatively small. To identify the cause of the pressure drop in the retruding jaw, pressure gradient components induced by flow were examined. Of note, vortical motion was highly associated with pressure drop. Structure simulation was performed to observe the deformation and collapsibility of soft tissue around the upper airways using the surface pressure obtained from the flow simulation. At peak flow rate, the soft tissue of the retruding jaw was highly expanded, and a collapse was observed at the oropharyngeal and epiglottis levels. NEW & NOTEWORTHY Aerodynamic characteristics have been reported to correlate with airway occlusion. However, a detailed mechanism of the phenomenon within the upper airways and its impact on airway collapsibility remain poorly understood. This study provides in silico results for aerodynamic characteristics, such as vortical structure, pressure drop, and exact location of the obstruction using a computational approach. Large deformation of soft tissue was observed in the retruding jaw, suggesting that it is responsible for obstructive sleep apnea.

Maxillary Expansion and Mandibular Setback Surgery With and Without Mandibular Anterior Segment Osteotomy to Correct Mandibular Prognathism With Obstructive Sleep Apnea.

Mandibular prognathism is usually treated with mandibular setback surgery. However, this approach reduces the pharyngeal airway space, and can aggravate obstructive phenomena in patients with obstructive sleep apnea (OSA). While maxillary expansion is known to lead to an increase in the pharyngeal airway volume (PAS), its effect on the PAS in mandibular setback surgery has not yet been reported. The authors report a surgical approach with maxillary expansion in 2 patients with mandibular prognathism that was accompanied by OSA: maxillary midsagittal expansion with minimum maxillary advancement and minor mandibular setback without mandibular anterior segmental osteotomy (ASO) or major mandibular setback with mandibular ASO. Preoperative and postoperative computed tomography and polysomnography indicated that OSA was improved and pharyngeal airway space was increased or sustained, and the prognathic profile could be corrected to an acceptable facial esthetic profile. In summary, maxillary transversal expansion and mandibular setback with or without mandibular ASO can be successfully applied to treat mandibular prognathism with OSA.

Are distinct etiologies of upper airway obstruction in mouth-breathing children associated with different cephalometric patterns?

OBJECTIVE: To test the null hypothesis that mouth-breathing (MB) children by distinct obstructive tissues present a similar cephalometric pattern. METHODS: The sample included 226 prepubescent children (113 MB and 113 nasal breathing (NB) controls). An ENT clinical examination, including flexible nasal endoscopy, orthodontic clinical and cephalometric examinations, was performed on the MB population. MB children were grouped into three categories, according to the obstructive tissues: 1) adenoid group (AG), 2) tonsillar group (TG), and 3) adenotonsillar group (ATG). The NB controls were matched by gender, age, sagittal dental relationship and skeletal maturation status. Lateral cephalometric radiography provided the cephalometric pattern comparisons between the MB and NB groups. RESULTS: MB cephalometric measurements were significantly different from those of NB children, exception in the SNB° (P=0.056). All comparisons between the three groups of MB children with the NB children showed a significant difference. Finally, even among the three groups of MB children, a significant difference was observed in the measurements of the SNB° (P<0.036), NSGn° (P<0.028) and PFH/TAFH ratio (posterior facial height/total anterior facial height) (P<0.012). CONCLUSIONS: The cephalometric pattern of MB and NB children was not similar. Cephalometric measurements of the MB group differed according to the etiology of upper airway obstruction. Children with isolated hypertrophy of the palatine tonsils presented with a mandible that was positioned more forward and upward compared to children obstructed only by the enlarged adenoid.

Influence of craniofacial and upper spine morphology on mandibular advancement device treatment outcome in patients with obstructive sleep apnoea: a pilot study.

BACKGROUND/OBJECTIVES: The aim of the study was to assess cephalometric predictive markers in terms of craniofacial morphology including posterior cranial fossa and upper spine morphology for mandibular advancement device (MAD) treatment outcome in patients with obstructive sleep apnoea (OSA). MATERIAL/METHODS: Twenty-seven OSA patients were treated with MAD for 4 weeks. Apnoea-hypopnoea index (AHI) was recorded before and after MAD treatment. The criteria of treatment success were 75 per cent reduction of AHI. Accordingly, two groups occurred: the success treatment group of 8 patients and the no success treatment group of 19 patients. Before MAD treatment lateral cephalograms were taken and analyses of the craniofacial morphology including the posterior cranial fossa and upper spine morphology were performed. Differences between the groups were analysed by Fisher's exact test, t-test, and multiple regression analysis. RESULTS: Upper spine morphological deviations occurred non-significantly in 25 per cent in the success treatment group and in 42.1 per cent in the no success treatment group. Body mass index (BMI; P < 0.05), maxillary prognathism (S-N-Ss; P < 0.01), mandibular prognathism (S-N-Pg; P < 0.05 and S-N-Sm; P < 0.01), and the distance between sella turcica and the deepest point in posterior cranial fossa (S-D; P < 0.05) was significantly smaller in the success treatment group. The maxillary prognathism (P < 0.05) was the most important factor for the MAD treatment outcome (R (2) = 0.47). LIMITATIONS: Relatively small sample size. CONCLUSIONS: The results indicate that BMI, posterior cranial fossa morphology, and retrognathia of the jaws are factors related to MAD treatment outcome. Furthermore, OSA patients with upper spine morphological deviations may respond poorer to MAD treatment.

Treatment effects of distal movement of lower arch with miniscrews in the retromolar area compared with miniscrews in the posterior area of the maxillary.

OBJECTIVE: The aim of this study was to compare the effects of group distal movement of lower teeth obtained with the aid of direct usage of miniscrews in the retromolar area and indirect usage of miniscrews in the posterior area of the maxillary. METHODS: Nineteen patients with mild-to-moderate class III malocclusion (4 males and 15 females) were divided into 2 groups. Ten patients (2 males and 8 females; mean age, 20.7 ± 2.5 years) in group 1 were treated by miniscrews in the retromolar area. Nine patients (2 males and 7 females; mean age, 21.5 ± 3.7 years) in group 2 were treated by miniscrews in the posterior area of the maxillary. Lateral cephalometric headfilms were taken at the beginning of treatment and after distal movement of mandibular dentition for the evaluation of the treatment changes. RESULTS: In group 1, the crown and root apex of lower first molars were moved distally by 3.4 mm and 1.2 mm with distal tipping of 8.7 degrees and intruded by 0.7 mm. In group 2, the crown and root apex of lower first molars were moved distally by 3.3 mm (P = 0.8976, P > 0.05) and 0.2 mm (P = 0.0124, P < 0.05) with distal tipping of 10.7 degrees (P = 0.0467, P < 0.05) and extruded by 0.2 mm (P = 0.0124, P < 0.05). Retraction of the mandibular arch lasted 6.31 ± 1.45 months for group 1 and 7.61 ± 1.46 months for group 2. CONCLUSIONS: Direct usage of miniscrews in the retromolar area took less time and more bodily movement to retract the lower arch without cooperation of the patients and was a better choice for the patients with potential temporomandibular joint disorders problems.

Morphologic relationship between the cranial base and the mandible in patients with facial asymmetry and mandibular prognathism.

INTRODUCTION: This study was conducted to measure the dimensional changes in the cranial base and the mandible in patients with facial asymmetry and mandibular prognathism, and to examine the morphologic relationship between asymmetries of the cranial base and the mandible. METHODS: The patients were 60 adults with mandibular prognathism, divided into a symmetry group (menton deviation, <2 mm; n = 30) and an asymmetry group (menton deviation, >4 mm; n = 30) according to the degree of menton deviation. Three-dimensional computed tomography scans were obtained with a spiral scanner. Landmarks were designated on the reconstructed 3-dimensional surface models. Linear, angular, and volumetric measurements of the cranial base and mandibular variables were made. RESULTS: In the asymmetry group, the hemi-base, anterior cranial base, and middle cranial base volumes were significantly larger (P <0.01), and crista galli to sphenoid, sphenoid to petrous ridge, anterior clinoid process to petrous ridge, and vomer to petrous ridge lengths were significantly longer (P <0.05) on the nondeviated side than on the deviated side. Menton deviation was significantly correlated with the difference in hemi-base volume, and ramal volume was significantly correlated with the difference in hemi-base and middle cranial base volumes between the nondeviated and deviated sides (P <0.05). CONCLUSIONS: In patients with facial asymmetry and mandibular prognathism, cranial base volume increased on the nondeviated side and was also correlated with mandibular asymmetry.

Submandibular-space abscess from loss of a bonded molar tube during orthognathic surgery.

The use of bonded orthodontic molar tubes is becoming more prevalent in orthodontics because they have some advantages over conventional bonding. However, a bonded apparatus can become detached, leading to complications. This article presents the case of a submandibular-space abscess associated with a molar tube that detached during orthognathic surgery and became embedded in the soft tissues. The site became infected, and antibiotics were prescribed. Eventually, the molar tube migrated and could be removed under local anesthesia.

Congenital macroglossia treated by 2-stage partial glossectomy.

Persistent macroglossia affects speech, swallowing, and the dentofacial skeleton. A range of tongue reduction methods have been proposed to preserve the mobility and sensation of the tongue. However, recent reports have shown that speech or esthetic problems still exists, even after a comprehensive glossectomy in early childhood. Because a large volume reduction of the anterior tongue in young growing children might result in a short tongue tip with functional difficulties, it is important to select the appropriate tongue reduction method considering the growth of the tongue.In the current report, a staged tongue reduction was planned to minimize the functional and esthetic problems after surgery. A 3-year-old girl visited our clinic because of congenital macroglossia, phonation problems, and prognathic appearance of the mandible. The tongue was first reduced by a central glossectomy. The speech intelligibility, tongue movement, and skeletal growth pattern were improved after the first surgery. The secondary peripheral tongue reduction was performed 6 years later to achieve an esthetically pleasing tongue appearance.This 2-stage partial glossectomy, central tongue reduction first followed later by a peripheral tongue reduction, ensures functional integrity of the tongue and can provide an esthetically pleasing result in growing children. The results demonstrated that this strategic combination of a staged tongue reduction can be a successful treatment option for macroglossia.

Class I malocclusion with severe bimaxillary protrusion: a successful result.

This case report describes the successful treatment of a 29-year-old young woman who had severe bimaxillary dento-alveolar protrusion, with the four premolars already extracted. Her face was convex, with a closed naso-labial angle, protruding and everted lower lip, associated with mentalis strain and a class I canine and molar relationships. After retraction of anterior teeth by using maximum anchorage mechanics through directional forces, facial changes were impressive, with a significant improvement of the dento-alveolar protrusion. Retraction of the incisors had corrected proquelia, reduced lips eversion and had improved the chin projection. As the lips were retracted, mentalis strain was reduced; this improved chin projection.

Temporomandibular disorders after orthognathic surgery in patients with mandibular prognathism with depression as a risk factor.

OBJECTIVE: To examine the prevalence of temporomandibular disorders (TMD) after orthodontic-surgical treatment in patients with mandibular prognathism and analyze psychosocial variables related to TMD. MATERIALS AND METHODS: The case-control study comprised 40 patients with mandibular prognathism who underwent combined orthodontic-surgical treatment (orthognathic surgery group). Forty-two patients with untreated mandibular prognathism served as a control group. Research diagnostic criteria for temporomandibular disorders was used in order to assess the clinical diagnosis of TMD (Axis I) and to estimate depression, somatization and patient's disability related to chronic pain (Axis II). RESULTS: The overall prevalence of TMD was not significantly different between the groups. Myofascial pain was significantly higher, while arthralgia, arthritis and arthrosis was significantly lower in the orthognathic group compared with the controls (90.5% vs 50.0%, 0.0% vs 27.8%, respectively) (p < 0.05). Females in orthognathic surgery group showed higher prevalence of TMD (p < 0.05) and myofascial pain (p < 0.01) and increased level of chronic pain (p < 0.05) in comparison with post-operative males. No significant difference in chronic pain, somatization and depression scores was found between investigated groups. With respect to presence of TMD within the groups depression was higher in untreated subjects with dysfunction (p < 0.05). CONCLUSION: Prevalence of TMD immediately after completion of orthodontic-surgical treatment for mandibular prognathism is similar to frequency of dysfunction in untreated subjects, is significantly higher in females and is most commonly myogenic. Furthermore, females show an increased level of chronic pain post-operatively. Somatization and depression levels do not differ between patients with corrected prognathism and untreated prognathic patients.

Dynamic changes in morphometric analysis in patients following Class III bimaxillary surgery.

BACKGROUND: Prognathism of the mandible is a skeletal Class III abnormality, caused either by excessive forward growth of the mandible or maxillary underdevelopment. OBJECTIVES: The aim of the study was to assess dynamic changes in morphometric analysis on subjects presenting with Class III malocclusions before orthodontic treatment, before bimaxillary surgery and after surgery. MATERIAL AND METHODS: The sample consisted of 30 non-growing patients, at the age of 18 to 30, treated with mandibular set-back sagittal split osteotomy and maxillary Le Fort I advancement. Cephalometric analysis by Segner and Hasund was performed. Lateral cephalograms were taken at the beginning of orthodontic treatment (T0), immediately before surgery (T1) and at least 3-6 months after surgery (T2). RESULTS: The results showed that there was normalization of the cephalometric variables after surgery. In the sagittal plane the following skeletal changes were observed: preoperative anterior mandibular growth confirmed by SNB increased angle was significantly reduced after surgery; preoperative decreased SNA angle largely increased after surgery. Statistically significant GntgoAr mandible angle decreased after surgery in relation to the beginning state. Also, the H angle was increased as a result of orthodontic-surgical treatment which influenced positively on face esthetics. CONCLUSIONS: The results of our study indicate that there was a significant improvement in the correlation between soft and hard tissue change in the facial profiles of the Class III bimaxillary surgery patients, which was improved by the H angle. The face's photographs and cephalometric analysis indicate, after the operation there is a decrease of total face length, but the lower part still remains longer than a middle part of the face.

Alveolar bone loss around lower incisors during surgical orthodontic treatment in mandibular prognathism.

OBJECTIVES: To evaluate the alveolar bone loss around lower incisors incurred during surgical orthodontic treatment in individuals with mandibular prognathism. MATERIALS AND METHODS: The samples consisted of 25 patients (13 men, 12 women; mean ages: 26.3 ± 2.7 years) treated with jaw surgery and orthodontic treatment. Lateral and frontal cephalograms and cone-beam computed tomography (CBCT) images of the patients were obtained before treatment (T0) and after presurgical orthodontic treatment (T1) and after debonding (T2). After measurement of variables, repeated-measures analysis of variance with Bonferroni's multiple comparison test and Pearson and Spearman correlation analysis were performed. RESULTS: The lower central and lateral incisors showed that the vertical alveolar bone level and the alveolar bone thickness of the labial and lingual plates were reduced after presurgical orthodontic treatment but were not deteriorated during postsurgical orthodontic treatment. CONCLUSION: Excessive forward movement of lower incisors during presurgical orthodontic treatment could cause alveolar bone loss around the lower incisors; thus, special care should be considered in individuals with mandibular prognathism.

Posterior crossbite and temporomandibular disorders (TMDs): need for orthodontic treatment?

The aim of this work was to update the bibliography regarding the concept of 'temporomandibular disorder (TMD)' and 'posterior crossbite' and try to find out if there is any association between some special signs/symptoms of TMD and type of posterior crossbite. A literature search from 1970 to 2009, due to specified criterion, resulted in 14 publications that were found to be relevant for the present systematic review. An association between TMD and posterior crossbite (Yes-group) was reported as often as absence of such a relationship (No-group). The samples in the two groups showed similarities as well as differences with respect to number, gender, and age. Most articles reported only on 'presence' or 'absence' of crossbite and only few on type of crossbite opposite to a thorough account of clinical signs and symptoms of TMD. This review seems, however, to state that a functional posterior crossbite (mandibular guidance with midline deviation) is associated with headache, temporomandibular joint and muscular pain, and clicking. As evident from the discussion, such type needs orthodontic treatment to rehabilitate the asymmetric muscular activity between the crossbite and non-crossbite sides and the changed condyle/temporal relationship caused by mandibular deviation. Whether this treatment also will avoid future TMD problems can be answered only after clinical follow-up studies have been performed.

Maxillofacial characteristics affecting chin deviation between mandibular retrusion and prognathism patients.

OBJECTIVE: To examine and compare the maxillofacial characteristics affecting chin deviation three-dimensionally in facial asymmetry patients with mandibular retrusion and mandibular prognathism. MATERIALS AND METHODS: Maxillofacial computed tomography (CT) scan data were obtained from 48 orthognathic surgery patients (24 cases of mandibular retrusion and 24 cases of mandibular prognathism) with facial asymmetry. Although chin deviation was assessed on the basis of the ANS-to-menton line on frontal cephalograms, its contributing factors were evaluated on three-dimensional CT images. Maxillary height, ramus length, frontal ramal inclination, lateral ramal inclination, mandibular body length, and body height were defined on each side, and right-left differences were calculated and analyzed. RESULTS: In an assessment of chin deviation, subjects in this study showed predominantly left side deviation regardless of the group, and the degree of menton deviation did not reveal significant differences between groups. In a comparison of right-left differences in contributing factors, all values were noted to be greater in the retrusion group, except for body height, which showed no difference between chin-deviated and contralateral sides. In particular, ramus length presented a statistically significant difference between the two groups. CONCLUSION: Based on the same degree of chin deviation in mandibular prognathism and retrusion in this study, results of right-left differences in contributing factors indicate that chin deviations are expressed easily in mandibular prognathism, whereas they occur only with significant right-left differences in relevant maxillofacial structures in individuals with mandibular retrusion.

Dental patient with acromegaly: a case report.

Acromegaly is an acquired disorder related to excessive production of growth hormone after epiphyseal closure of bones. It is characterized by progressive somatic disfigurement (mainly involving the face and extremities) and systemic manifestations. The prevalence is estimated at 1:140,000-250,000. Although acromegaly rarely manifests in the orofacial regions, it must be considered in patients who develop malocclusion after adolescence. Here, we present a case of acromegaly with brief review of the literature.

Stress change on the temporomandibular joint in mandibular prognathism subjects with asymmetry after orthognathic surgery.

The purpose of this study was to evaluate changes in stress on the temporomandibular joint (TMJ) in 80 Japanese subjects (21 males and 59 females, mean age 23.7 years) with mandibular prognathism, with and without asymmetry after orthognathic surgery using the rigid bodies spring model (RBSM). The asymmetric group consisted of 40 subjects whose Mx-Md midline was more than 3 degrees. The remaining 40 subjects formed the symmetric group. The geometry of the stress analysis model was based on frontal cephalograms of the subjects. Menton (Me), the centre point of occlusal force on a line connecting the bilateral buccal cusps of the second molars, and the most lateral, superior, and medial points on the condyle were plotted on a computer display and stress on the condyle was calculated with the two-dimensional RBSM program, Fortran. The degree (force partition) of the resultant force, the direction (angulation), and the displacement (X, Y) of each condyle were calculated and the horizontal displacement (u), the vertical displacement (v), and rotation displacement (theta) of the mandibular body at Me were calculated pre- and post-operatively. The data was analysed using paired and unpaired t-tests. For the vertical (v) and rotational (theta) displacement, the post-operative value was smaller than the pre-operative value (v: P < 0.001, theta: P = 0.0063) in the asymmetric group. For angulation and the X-component, the post-operative value was smaller than that pre-operatively on the deviated (angulation: P = 0.0074, X-component: P = 0.0003) and non-deviated (angulation: P = 0.0024, X-component: P = 0.001) side in the asymmetric group. However, there was no significant difference between the pre- and post-operative value for any parameter in the symmetric group. These findings suggest that surgical correction of mandibular prognathism, with and without asymmetry, could induce an improvement in stress balance on the TMJ in the frontal aspect.