Mandibular Sagittal Position Research Articles

New Method to Assess Sagittal Jaw Position: TWM and TWG Angles: A Cephalometric Study

Aim The aim of the study was to develop new cephalometric angles TWM (T-Tuberculum sella, W-wing point, M-maxillary point) and TWG (T-Tuberculum sella, W-wing point, G point-center of mandibular symphysis) and to assess and evaluate the newly developed angles in determining the maxillary and mandibular sagittal position, respectively. Materials and Methods Ninety pretreatment lateral cephalograms from the records of Department of Orthodontics and Dentofacial Orthopaedics were traced and divided equally into three groups as class I, class II, and class III based on cephalometric values of ANB angle and WITS appraisal. Further for each radiograph, angles such as SNA, TWM, SNB, and TWG were measured and recorded. The TWM angle (Maxilla) was formed using the points T-Tuberculum sella, W-wing point, M-maxillary point, and the TWG angle (mandible) was formed using the points T-Tuberculum sella, W-wing point, G point-center of mandibular symphysis. Results The mean values of TWM and TWG angles for the class I group were 120.1°± 3.6° and 101.4 ± 3.7°, respectively. The one-way analysis of variance (ANOVA) was used followed by Tukey post hoc testing to determine whether there was a statistically significant difference between the mean values of the three groups. A p value ≤ .05 was considered to be statistically significant. Pearson correlation test revealed a strong correlation between SNA and TWM angles and similarly between SNB and TWG angles. Conclusion The two new angles, TWM for maxilla and TWG for mandible established, can be used as an alternative for assessing the sagittal position of the jaw bases and will give a clearer picture, as stable and reproducible landmarks are used.

Treatment of Class II Malocclusion in the Growing Patient: Early or Late?

The aim of this paper is to evaluate several factors that can improve the efficacy of Class II treatment in the growing patient with mandibular skeletal retrusion. Previous research has shown that functional appliances are most effective in altering short-and long-term mandibular growth and mandibular sagittal position if active treatment includes the pubertal growth spurt. If functional jaw orthopedic treatment is initiated in the prepubertal growth period, the positive occlusal changes are primarily dentoalveolar in nature. The staging of the maturation level of the cervical vertebrae (CVM method) has proven effective in differentiating the stages of maturation.The second factor, typically not considered routinely during the decision-making process, is the responsiveness of a specific patient to the prescribed treatment. Not all patients respond to the same treatment in the same manner. One way of predicting individual patient responsiveness is to evaluate mandibular morphology at puberty. Good responders to functional jaw orthopedics for Class II malocclusion with mandibular retrusion are characterized by a small mandibular angle (Co-Go-Me). Poor responders have larger mandibular angles.The third issue that is addressed is the question of whether an early phase of treatment is necessary in a Class II patient with mandibular skeletal retrusion. The most frequently seen deficiency in the early mixed dentition is narrowness of the maxilla. A measurement of transpalatal width between the closest points between the maxillary first permanent molars of 35-39 mm usually indicates that there is enough arch perimeter to accommodate teeth of normal size. If transpalatal width is constricted, an acrylic splint expander or a banded expander can be used to widen the maxilla. A removable lower Schwarz expander also can be used to gain a modest amount of lower arch perimeter while uprighting the lower posterior teeth. Rapid maxillary expansion in the early mixed dentition can help in improving Class II malocclusion as a side-effect, both skeletally and dentally.

Restricted upper airway dimensions in patients with dentofacial deformity from juvenile idiopathic arthritis

BackgroundThis retrospective, cross-sectional study aimed to assess the pharyngeal airway dimensions of patients with juvenile idiopathic arthritis (JIA) and moderate/severe JIA-related dentofacial deformity (mandibular retrognathia/micrognathia), and compare the results with JIA patients with a normal mandibular appearance and a group of non-JIA patients.MethodsSeventy-eight patients were retrospectively included in a 1:1:1 manner as specified below. All patients had previously been treated at the Section of Orthodontics, Aarhus University, Denmark. All had a pretreatment cone beam computed tomography (CBCT). Group 1 (JIA+); 26 JIA patients with severe arthritis-related dentofacial deformity and mandibular retrognathia/micrognathia. Group 2 (JIA-); 26 JIA patients with normal mandibular morphology/position. Group 3 (Controls); 26 non-JIA subjects. Dentofacial morphology and upper airway dimensions, excluding the nasal cavity, were assessed in a validated three-dimensional (3D) fashion. Assessment of dentofacial deformity comprised six morphometric measures. Assessment of airway dimensions comprised nine measures.ResultsFive morphometric measures of dentofacial deformity were significantly deviating in the JIA+ group compared with the JIA- and control groups: Posterior mandibular height, anterior facial height, mandibular inclination, mandibular occlusal inclination, and mandibular sagittal position. Five of the airway measurements showed significant inter-group differences: JIA+ had a significantly smaller nasopharyngeal airway dimension (ad2-PNS), a smaller velopharyngeal volume, a smaller minimal cross-sectional area and a smaller minimal hydraulic diameter than JIA- and controls. No significant differences in upper airway dimensions were seen between JIA- and controls.ConclusionJIA patients with severe arthritis-related dentofacial deformity and mandibular micrognathia had significantly restricted upper airway dimensions compared with JIA patients without dentofacial deformity and controls. The restrictions of upper airway dimension seen in the JIA+ group herein were previously associated with sleep-disordered breathing in the non-JIA background population. Further studies are needed to elucidate the role of dentofacial deformity and restricted airways in the development of sleep-disordered breathing in JIA.

Rapid Maxillary Expansion in Pediatric Patients with Sleep-Disordered Breathing: Cephalometric Variations in Upper Airway’s Dimension

Rapid maxillary expansion (RME) is considered an effective treatment in the management of sleep-disordered breathing (SDB) and malocclusions in pediatric patients, not only because it is able to correct the transverse maxillary deficiency, but it also widens the floor of the nasal cavities, leading to a drastic and immediate reduction in air resistance and facilitating a normal nasal breathing pattern. The aim of this study was to evaluate cephalometric changes in the upper airway’s dimensions and facial morphology in pediatric SDB patients treated with RME, comparing data with a no-SDB group treated with RME for malocclusion. In this retrospective study, pre-treatment and post-treatment cephalometric variables were measured on lateral skull radiographs from 20 SDB pediatric patients (nine males and 11 females) aged 6 to 9 years (mean age 7.61 ± 0.6), treated with a rapid maxillary expander, and 20 control patients without SDB (nine males and 11 females) aged 6 to 11 years (mean age 8.4 ± 0.5). In both groups, there were statistically significant changes in the variables indicating the airway’s dimensions and mandibular sagittal position in relation to the cranial base, with a skeletal class II correction in SDB children. Rapid maxillary expansion is associated with an increase in upper-airway dimensions in SDB children, as well as in control healthy subjects, with a possible correction of class II relationship.

Comparing Clinical and Radiological Manifestations of Adolescent Idiopathic Condylar Resorption and Juvenile Idiopathic Arthritis in the Temporomandibular Joint

This cross-sectional study compared orofacial manifestations at the time of diagnosis in 2 temporomandibular joint (TMJ) conditions: adolescent idiopathic condylar resorption (ICR) and TMJ involvement from juvenile idiopathic arthritis (JIA). This retrospective study included 19 JIAs, 19 ICRs, and 19 control patients, all treated at the Section of Orthodontics, Aarhus University Craniofacial Clinic, Denmark. From patient files, we retrieved radiological data from cone-beam computed tomographies along with information on symptoms and orofacial function at the time of diagnosis. Validated methodologies were used to evaluate TMJ and dentofacial morphology. We found no statistically significant intergroup differences in severity of deformation of TMJ structures (TMJ deformity) between JIA and ICR patients. However, the ICR group showed significantly greater signs of dentofacial deformity on 4 outcome variables: mandibular inclination, posterior/anterior lower face height ratio, mandibular sagittal position, and mandibular occlusal plane inclination. Significant intergroup differences in clinical presentation were seen in 5 of 20 variables. Thus, the JIA group reported significantly more symptoms of TMJ pain, TMJ morning stiffness, and TMJ pain on palpation during the clinical examination, whereas the ICR group reported significantly more TMJ clicking during function and had a higher proportion of patients with anterior open bite. Cone-beam computed tomography examination showed a similar degree of TMJ deformity in ICR and JIA patients at the time of diagnosis. ICR patients presented with a significantly higher degree of dentofacial deformity than JIA patients and healthy controls, which relates to the timing of the diagnosis. Arthralgia, TMJ morning stiffness, and TMJ palpitation pain were more common in JIA patients, whereas TMJ clicking during function and anterior open bites were more common in ICR patients.

Does Gender Have an Effect on Craniofacial Measurements?

The aim of this cross-sectional study was to evaluate craniofacial structures in terms of different sagittal relations and gender in adolescent individuals. Pre-treatment dental models, lateral cephalometric, and hand-wrist radiographs of 223 adolescent subjects (102 male, 121 female) were evaluated. Subjects were divided into the Angle Class I, II, and III (skeletally) subgroups according to the ANB angle. Four angular and 33 linear measurements were used to evaluate the lateral cephalometric radiographs relative to the R1 and R2 coordinate system. The Kolmogorov-Smirnov test was performed to assess the normal distribution of the data. The independent samples t-test and Mann-Whitney U test were used for the comparison of male and female subjects in each group. The values were considered statistically significant at p<0.05. The vertical facial dimension was found to be significantly greater in Class I male subjects than in female subjects (SGo, p=0.023; ANS-M, p=0.036), and there was a protrusive maxilla (R2ANS, p=0.038; R2A, p=0.016), while the mandibular sagittal position and the mandibular dimension were similar. The maxilla was placed protrusively (R2ANS, p=0.001; R2A, p=0.002), while the mandible was found to be larger both in the position and dimension (CoGn, p=0.003; R2M, p=0.014) in Class II male subjects. Class III male and female subjects were found to have similar maxillary and mandibular vertical and sagittal location and dimensions. Class I and II subjects showed more gender variation than Class III subjects. The gender-related results of this study declare that treatment planning of malocclusions should be based on gender differences rather than general treatment procedures, which will be useful in achieving successful orthodontic treatment results.

Correlation of Cephalometric Analyses With Clinical Impression in Orthognathic Surgery Patients: Harvold and Steiner Analyses

A variety of linear (Harvold) and angular (Steiner) cephalometric analyses are used to identify the skeletal basis for a malocclusion; there is no universally accepted standard. The purpose of this study was to compare the concordance of Harvold and Steiner analyses with the clinicians' impression of maxillary and mandibular jaw position. We conducted a retrospective cohort study of patients who underwent orthognathic surgery at Massachusetts General Hospital from 2012 through 2016. Patients were included if they had symmetrical deformities not related to trauma, clefts, or syndromes; complete records; and a clinical diagnosis documented at initial consultation. The predictor variables were Harvold- and Steiner-derived diagnoses of jaw position (hypoplasia, neutral, or hyperplasia). The outcome variables were maxillary and mandibular clinical impressions (hypoplasia, neutral, or hyperplasia). The concordance, sensitivity, specificity, positive predictive value (PPV), and negative predictive value relative to clinical diagnoses were calculated. During the study period 388 patients had orthognathic surgery and 222(112 females, mean age 26.4±9.9 years) met the inclusion criteria. Harvold and Steiner analyses were 82% and 33% concordant with the maxillary clinical impression, respectively (P<.001), and 62% and 52% concordant with the mandibular clinical impression, respectively (P=.044). Steiner analysis had greater concordance in females (P<.001). For maxillary hypoplasia, the maxillary unit length had a sensitivity of 87%, specificity of 36%, and PPV of 92% and the sell-nasion-A (SNA) point had 28%, 84%, and 93%, respectively.For mandibular hypoplasia, the mandibular unit length had a sensitivity of 52%, specificity of 96%, and PPV of 94% and the sell-nasion-B (SNB) point had 52%, 98%, and 97%, respectively. For mandibular hyperplasia, the mandibular unit length had a sensitivity of 46%, specificity of 93%, and PPV of 40% and the SNB point had 73%, 73%, and 23%, respectively. Harvold analysis was significantly more consistent with the clinical impression of the maxillary and mandibular sagittal position than Steiner analysis. Both analyses were highly specific and had high PPVs to confirm the clinical impression. Clinicians should consider incorporating Harvold analysis during treatment planning for orthognathic surgery.

Development of a Normative Data Set for the Normal Adult Airway Using 772 Cone Beam CT Scans

sized that upper airway length would be longer in patients with OSA and strongly correlated with disease severity. Methods of Investigation: This was a case-control study utilizing a sample of cases defined as adult subjects with OSA, confirmed by polysomnography, and controls who were adult patients with skeletal Class II malocclusions (non-syndromic mandibular or bimaxillary retrognathia) without history or symptoms of OSA. The primary predictor variable was UAL, which was measured as the distance along the long axis of the airway from the hyoid bone to the palatal plane. Two observers, blinded to the disease status of the subjects, independently evaluated airway length to assess the reliability of the measurement method. The technique had a high degree of inter-examiner correlation (intra-class correlation coefficient 0.96, p 0.001). Other variables were demographic (age, sex and body mass index, BMI) and cephalometric (maxillary sagittal position, SNA; mandibular sagittal position, SNB; maxillomandibular relationship, ANB; maxillary length, Co-ANS; mandibular length, CoGn; posterior airway space, PAS; hyoid-mandibular perpendicular distance, HMP; soft-palate length, PNS-SP; maxillary vertical length, S-PNS) parameters. The respiratory disturbance index (RDI) was used to measure disease severity in cases. Methods of Analysis: Bivariate and multiple regression analyses were computed to evaluate the association between predictor and outcome variables adjusted as indicated for confounders or effect modifiers. Diagnostic test characteristics were computed for threshold airway lengths. A p-value 0.05 was statistically significant. Results: Over a five-year period, we identified 96 cases with OSA (76 males) and 56 controls (36 males). OSA subjects were older, predominately male, had higher BMIs, and longer and narrower airways (P 0.05). The OSA group had a mean RDI of 51.3 31.4 events/hr. After controlling for confounding variables, UALs 72 mm for males and 62 mm for females were significantly associated with presence of OSA. Using these thresholds as a diagnostic test for the presence of OSA, the sensitivity and specificity were 0.8. UAL was strongly correlated with RDI in males (r 0.72, p 0.01) and moderately correlated with RDI in females (r 0.52, p 0.01). Conclusion: Upper airway length can be reliably measured on lateral cephalograms and is correlated with the presence and severity of OSA in adult patients.

Influência do posicionamento sagital mandibular na estética facial

OBJETIVO: avaliar a influência do posicionamento sagital da mandíbula na determinação da atratividade facial. MÉTODOS: fotografias faciais de perfil foram tomadas de um homem negro e um branco, assim como de uma mulher negra e uma branca. Essas fotografias foram manipuladas no computador, utilizando o programa Adobe Photoshop CS2®, a fim de produzir, a partir de cada face original, um perfil reto, três simulando discrepâncias mandibulares por retrusão e três por protrusão. As 28 fotografias foram avaliadas por ortodontistas (n = 20), cirurgiões bucomaxilofaciais (n = 20), artistas plásticos (n = 20) e leigos (n = 20). A análise descritiva foi realizada a partir do cálculo da média e desvio-padrão em cada grupo. RESULTADOS: para as faces do homem negro, bem como para as faces femininas, o perfil reto foi o mais aceito. Para o homem branco, a face considerada mais agradável apresentava um perfil levemente côncavo, com a mandíbula mais proeminente. Nesse, analisando-se as simulações de discrepâncias esqueléticas, houve predileção pela protrusão mandibular, em detrimento da retrusão. Contudo, para as faces femininas, os perfis côncavos foram mais rejeitados do que os convexos. CONCLUSÃO: os resultados demonstraram concordância entre os grupos de avaliadores na escolha dos perfis mais atrativos. Para as faces masculinas, o perfil reto e a face levemente côncava apresentaram-se mais atrativos, já as faces femininas que foram consideradas mais atrativas possuíam o perfil reto.

Effect of a Syndromic Diagnosis on Mandibular Size and Sagittal Position in Robin Sequence

Despite its pathogenic heterogeneity, it is often assumed that the small mandible in a neonate with Robin sequence will not grow normally. The purpose of this study was to determine mandibular length and position in patients with nonsyndromic versus syndromic Robin sequence. Lateral cephalograms of 51 children with Robin sequence were analyzed. Group I consisted of nonsyndromic (NS) subjects and group II consisted of subjects with the 4 most common syndromic (S) diagnoses. Cephalometric measurements included sella-nasion-A point (SNA), sella-nasion-B point (SNB), sella-nasion-pogonion (SNPg), articulare-gonion-pogonion (ArGoPg), temporomandibular joint-pogonion (TmPg), articulare-gonion (ArGo), and gonion-pogonion (GoPg). Differences between groups and subgroups were compared using t test. There were 26 NS patients (mean age, 6.8 yrs) and 25 S patients (mean age, 8.7 yrs); mean age was statistically different between groups (P = .04); therefore, cephalometric measurements were compared with age-matched normal values. Syndromes included Stickler (n = 10), bilateral facial microsomia (n = 8), velocardiofacial (n = 4), and Treacher Collins (n = 3). SNA was statistically different from normal in both groups (NS, P = .017; S, P = .007); however, SNB was not different from normal for either group (NS, P = .175; S, P = .537). SNPg (0.007) was significantly greater than normal in NS (P = .007) but not in S (P = .702) patients. SNA, SNB, and SNPg were not significantly different between groups. In both groups, mandibular length was short (P = .00), especially in S patients (P = .049), mandibular body was small (NS, P = .00; S, P = .00), and the gonial angle more obtuse (NS, P = .006; S, P = .000) than normal. Ramus length was significantly shorter than normal only in S patients (P = .019). Mandibular length (TmPg) was smaller than normal in all S subgroups but with wide variability. There were statistically significant differences among S subgroups with respect to mandibular sagittal position (SNB, P = .00; SNPg, P = .00) and mandibular length (TmPg, P = .008). There were no differences in S subgroups with respect to age, SNA, ArGo, GoPg, and ArGoPg. Mandibular morphology and position are variable in Robin sequence, based on the presence and type of associated syndromic diagnosis.

Severe retrognathia as a risk factor for recent onset painful TMJ disorders among adult females

To evaluate the importance of severe retrognathia as a risk factor for the development of recent onset painful TMJ disorders among adult females. Case-control study. This study was conducted in a large health maintenance organization between 1998 and 1999 [Kaiser Permanente Northwest (KPNW), Portland, OR, USA]. Adult females with recent onset painful TMJ disorders (n=29) and normal controls (n=104). Cases were recruited from the TMD clinic at Kaiser Permanente Northwest (KPNW). Controls were recruited from a dental clinic at KPNW. Case status was determined using a questionnaire; mandibular sagittal position was determined by measuring a research angle on facial photographs. The mean research angle for cases was compared to the mean for controls. Multivariable exact conditional logistic regression analysis was used to examine the demographic characteristics of cases and controls, and to determine the strength of association between recent onset painful TMJ disorders and severe retrognathia. The population attributable risk percentage (PAR%) and the attributable risk percentage (AR%) were calculated to further evaluate severe retrognathia as a risk factor. The mean research angle among cases (67.7 degrees; 95% CI=66.0-69.4) was smaller than among controls (71.6 degrees; 95% CI=70.7-72.5, P<0.001). The odds ratio for the association between case status and the presence or absence of severe retrognathia was elevated (OR=6.3; 95% CI=1.1-47.5, P=0.039). The PAR% and AR%, associated with severe retrognathia, were 13.3 and 84.1%, respectively. Severe retrognathia is strongly associated with recent onset painful TMJ disorders (OR=6.3). Only a small proportion of these disorders are attributable to severe retrognathia among the total population of adult females (PAR%=13.3%). However, a large proportion of these TMJ disorders are potentially attributable to severe retrognathia among adult females with severe retrognathia (AR%=84.1%).

Association between mandibular retrognathia and TMJ disorders in adult females.

This study assesses the association between temporomandibular joint (TMJ) disorders and mandibular retrognathia. We conducted a case-control study among women, aged 18-70 years, recruited from Kaiser Permanente Northwest Division (KPNW, Portland, OR) and Group Health Cooperative of Puget Sound (GHC, Seattle, WA). Cases (N= 160) were women seeking treatment for TMJ disorders at KPNW and GHC clinics. Controls (N=151) were women without TMJ disorders, selected from among adult female dental hygiene patients at KPNW or GHC enrollees. Case status was determined by questionnaire; mandibular sagittal position (orthognathic, mildly retrognathic, severely retrognathic, or prognathic) was measured using digitized facial photographs. Odds ratios (OR) and associated 95 percent confidence intervals (CI) estimated the magnitude of the association between TMJ disorders and mandibular sagittal position. Women with TMJ disorders were 4.0 times (95% CI=1.5, 10.8) more likely than controls to have severe retrognathia; no association with mild retrognathia or prognathia was seen. Results were similar when cases were restricted to those with recent onset of TMJ pain (OR=6.3; 95% CI=1.8, 21.8). We found a strong association between TMJ disorders and severe mandibular retrognathia in adult females. In some women this likely resulted from TMJ disorders influencing mandibular development over time. However, among a subset of women, our data support the reverse hypothesis--that severe mandibular retrognathia may influence the development of TMJ disorders. Despite this strong association, abnormal mandibular position contributed only a small portion to the overall rate at which women sought treatment for TMJ disorders.

Relationship of natural head position to craniofacial morphology

This investigation aimed at discussing the utility of natural head position–based cephalometric variables and to evaluate the relationship between natural head position and craniofacial morphology. Lateral facial photographs and cephalograms of 284 young adult males taken in a natural head position were analyzed. The average inclination of the intracranial reference planes, Frankfurt horizontal, and palatal plane, in relation to the true horizontal were nearly similar and smaller than 1°. Variables based on the true vertical to describe mandibular sagittal position like B-N(vert) and Pg-N(vert) had very high variances. To study the topographic error, flexors and extenders were identified on basis of four positional variables: NSL/VER; FH/VER; PP/VER; and PMvert/VER. Only 15 measurements were different, according to at least 2 of the 4 positional variables. The 3 that were different in all categories were: facial axis (NBa/PmGn), lower face height (ANS-Me), and the facial ratio (N-ANS/ANS-Me). The “extenders” had higher values for the facial axis and lower face height, and smaller for the face height ratio. Besides these 3 measurements, there was a tendency for the extenders to have increased anterior vertical height, distal sagittal relations, and smaller and retrognathic mandibles. Correlation coefficients between postural and morphologic variables tended to confirm these observations. (Am J Orthod Dentofacial Orthop 2000;117:406-17)