High Mandibular Plane Angle Research Articles

Relationships between the root-crown ratio and the loss of occlusal contact and high mandibular plane angle in patients with open bite

To determine the root-crown (R/C) ratio and dental root length of teeth in patients with open bite and seek any relationships with occlusal contact (OC) and the mandibular plane (Mp) angle. Thirty-one patients with open bite with negative overbite of at least four anterior teeth and 31 control patients with clinically normal overjet and overbite were enrolled. R/C ratios, dental root length, OC, and Mp angle were measured using panoramic radiographs, dental casts, and cephalograms, respectively. Mean differences between the groups, and variations between the R/C ratio or root length and Mp angle in patients with open bite were statistically analyzed. R/C and OC ratios from the incisors to premolars were significantly lower for patients with open bite than for controls, and some teeth had short dental roots. Relationships between low R/C ratio or root length and high Mp angle were significant in patients with open bite. Patients with open bite, especially those with a high Mp angle, have an unfavorable R/C ratio and short dental roots in some teeth, which may be related to the loss of OC.

Do skeletal cephalometric characteristics correlate with condylar volume, surface and shape? A 3D analysis

ObjectiveThe purpose of this study was to determine the condylar volume in subjects with different mandibular divergence and skeletal class using cone-beam computed tomography (CBCT) and analysis software.Materials and methodsFor 94 patients (46 females and 48 males; mean age 24.3 ± 6.5 years), resultant rendering reconstructions of the left and right temporal mandibular joints (TMJs) were obtained.Subjects were then classified on the base of ANB angle the GoGn-SN angle in three classes (I, II, III) . The data of the different classes were compared.ResultsNo significant difference was observed in the whole sample between the right and the left sides in condylar volume.The analysis of mean volume among low, normal and high mandibular plane angles revealed a significantly higher volume and surface in low angle subjects (p < 0.01) compared to the other groups.Class III subjects also tended to show a higher condylar volume and surface than class I and class II subjects, although the difference was not significant.ConclusionsHigher condylar volume was a common characteristic of low angle subjects compared to normal and high mandibular plane angle subjects. Skeletal class also appears to be associated to condylar volume and surface.

Class II high angle case for which titanium screws were added after mandibular posterior rotation

In skeletal Class II patients with a high mandibular plane angle, it is well known that posterior rotation of the mandible often occurs during treatment using a preadjusted edgewise appliance. In this case, posterior rotation of the mandible with increased overjet occurred after the buccal inclination of the mandibular 2nd molars. This case report describes a Class II high angle case for which titanium screws were added as an absolute anchorage to improve the posterior rotation of the mandible. To correct the posterior rotation of the mandible, mandibular molars were intruded and the mandibular arch was mesially moved using titanium screws. The treatment results show that titanium screws were useful for improving the posterior rotation of the mandible during treatment using a preadjusted edgewise appliance.

Over-bite and Vertical Changes following First Premolar Extraction in High Angle Cases

Orthodontists generally agree that nonextraction treatment is associated with downward and backward rotation of the mandible and an increase in the lower anterior face height (LAFH). They also agree that extraction line of treatment is associated with upward and forward rotation of the mandible and decrease in the LAFH. The intent of this cephalometric investigation was to examine the wedge hypothesis, that the vertical dimension collapses after first bicuspid extraction. The present study was undertaken to evaluate the cephalometric overbite and vertical changes following first premolar extraction in high angle cases. Forty-five adult patients having high mandibular plane angle, i.e. Gogn--SN more than or equal to 32° having class I molar and canine relation were included. Pre and post-treatment lateral cephalograms were measured and compared to analyze the cephalometric changes. There was no decrease in the overbite and vertical changes following first premolar extraction in high angle cases. The facial complex does increase in size with growth, but mandibular plane while moving inferiorly, remain essentially parallel to its pretreatment position due to residual growth and treatment mechanics. The study concluded that, There was no decrease in the vertical facial dimension, overbite and mandibular plane angle. However, it should be interpreted with caution, given the small sample size.

Associations between sleep-disordered breathing symptoms and facial and dental morphometry, assessed with screening examinations

Chronic snoring is considered abnormal in a pediatric population. This disorder is often attributed to enlarged tonsils and adenoids, but multiple anatomic obstructions should also be considered. Facial and dental morphometry associations with various sleep-disordered breathing symptoms were investigated at an orthodontic clinic. Parents or guardians were asked to complete a 4-part questionnaire on behalf of their children (n = 604; <18 years of age), including medical and dental history, bruxism and temporomandibular disorder habits, sleep and daytime behavior, and sleep duration and quality. All subjects underwent a clinical screening assessment by the same orthodontist to identify standard dental, skeletal, functional, and esthetic factors. In contrast to sleep-disordered breathing or sleep apnea in adults, which is predominantly associated with obesity, sleep-disordered breathing symptoms in this pediatric cohort were primarily associated with adenotonsillar hypertrophy, morphologic features related to a long and narrow face (dolichofacial, high mandibular plane angle, narrow palate, and severe crowding in the maxilla and the mandible), allergies, frequent colds, and habitual mouth breathing. Because of the recognized impact of pediatric snoring on children's health, the determination of these good predictors can help in preventing and managing sleep-disordered breathing. If a health professional notices signs and symptoms of sleep-disordered breathing, the young patient should be referred to a sleep medicine specialist in conjunction with an orthodontist if there are dentoskeletal abnormalities.

Orthognathic treatment and temporomandibular disorders – part 1

MEDLINE, bibliographies, and reference lists of identified publications and reviews, were utilised, along with personal communications with experts and specialists. Randomised controlled trials (RCT), cohort studies and case-control studies were included if participants (of age 14 years or over) received orthognathic treatment. Studies were excluded if participants had either craniofacial syndromes or cleft lip or palate; a history of facial fractures from trauma; were undergoing orthognathic surgery purely to correct TMD; or orthognathic treatment and concomitant joint disc surgery; or, finally, if they were animal studies. Data extraction was conducted independently by two reviewers, and any discrepancies discussed until agreement was reached. A quality-assessment scale was constructed specifically for this study with sections for selection, performance, measurement and outcome, and attrition. A narrative synthesis is presented as meta-analysis was not either feasible or appropriate. A total of 53 articles (41 cohorts, 8 case-control and 3 RCT) were analysed for the review. Almost half (20) did not explicitly state whether the study was retrospective or prospective, it could be determined for the majority with 21 being retrospective, 28 prospective and, in the case, four articles not being sufficiently clear. There was great variability between studies in their assessment of any association between TMD and orthognathic treatment. This variability included how TMD was classified, the signs and symptoms recorded, and the time intervals reported. Perhaps most important was the great variation in the malocclusions in the studies. Although some studies included participants with a specific skeletal discrepancy, others included various skeletal deformities, so that comparisons were not always possible and, when carried out, could be a source of heterogeneity. Most studies that did report a reduction in TMD signs and symptoms after orthognathic treatment reported this association in skeletal Class II patients. A decrease was reported in some studies in the prevalence of signs and symptoms of more than 50% of people postsurgery, compared with the presurgery state, whereas fewer subjects with skeletal Class III or a high mandibular plane angle seemed to benefit from surgery. Thus, the participants' skeletal deformity could have had a direct impact on TMD, especially after surgery. The diversity of diagnostic criteria and classification methods used in the included studies makes interstudy comparisons difficult. Well-designed studies are needed that have standardised diagnostic criteria and classification methods for TMD.

Postoperative Functional Remodeling of Preoperative Idiopathic Condylar Resorption: A Case Report

d Idiopathic condylar resorption (ICR) is a condition in which the condylar head of the mandible resorbs partially or completely, leading to alterations of facial morphology and occlusion of the jaw. The possible etiologies of ICR include overloading of the condyle, poor bone quality, and reduction of vascular supply to the condyle, but the etiology and pathogenesis of his condition remain poorly understood. ICR is observed after orthognathic surgery in patients with mandibular hypoplasia and a high mandibular plane angle. When ICR occurs, it induces everal changes that can be seen on a cephalogram. In any cases the resorption occurs on the superoanteior surface of the condylar head. As a result, the hortened ramus height leads to decreased posterior acial height, clockwise mandibular rotation with an ncreased mandibular plane angle, and a decreased ella-nasion-B point angle. Usually, condyles in patients with ICR after orthognathic surgery show progressive resorption with a flattened and malformed condylar shape. We report a case that showed functional remodeling of the condyle in preoperative ICR, where the patient had normal temporomandibular joint (TMJ) function with anatomic reshaping of the condyle after orthognathic surgery.

Volumes faciaux et typologie verticale : étude comparative tridimensionnelle

The purpose of this study was to compare the volume of facial cavities in untreated young subjects with long- and short-faces. Two groups of thirty subjects each, one with low (GoGn-SN < or = 28 degrees), and the other with high (GoGn-SN > or = 36 degrees) mandibular plane angles, ages between 18 to 30 years, were selected. For each subject, volumes of orbital, sinusal and buccal cavities were measured from CT scans with the AMIRA software. The statistical studies were performed using Kolmogorov-Smirnov, followed by Student "t" test (p < 0.05). Results suggest that there is no statistically significant difference between the volume of facial cavities in long- and short-face subjects. Only the ratio of nasal cavity volume to the total volume is significantly smaller in the short-face group. A compensatory phenomenon might exist between the three directions of growth to equilibrate an excess or deficit of the vertical dimension, thus maintaining constant the volume of facial cavities.

Skeletal Stability and Complications of Bilateral Sagittal Split Osteotomies and Mandibular Distraction Osteogenesis: An Evidence-Based Review

To provide an evidence-based review comparing the skeletal stability and complications of bilateral sagittal split osteotomies (BSSOs) and mandibular distraction osteogenesis (MDO) in the treatment of mandibular hypoplasia. A Medline search from January 1957 to December 2007 was performed wherein articles were retrieved on the basis of a set of inclusion and exclusion criteria. Data on mean skeletal stability and complications for the 2 techniques were retrieved from these articles. Based on the articles about stability, patients undergoing BSSO or MDO with an advancement or lengthening between 6 and 10 mm showed a similar mean skeletal relapse of 15.0% and 17.1%, respectively, within postoperative months 6 to 12. Greater skeletal relapse was reported for BSSO patients with high mandibular plane angles compared with normal mandibular plane angle patients (29.6% vs 11.3%). Based on the articles about complications, patients who underwent MDO showed a lower incidence of persistent inferior alveolar nerve disturbance (2.9%) and condylar resorption (1.4%) compared with BSSO patients, in whom the incidence of these conditions was 27.8% and 6.1%, respectively. Both BSSO and MDO showed similar relapse rates for mandibular advancements between 6 and 10 mm. Both techniques may also share similar risk factors for skeletal relapse. BSSO has a higher incidence of persistent neurosensory disturbances and condylar resorption than MDO. Randomized controlled trials of these 2 techniques are still lacking.

Class II Division 1 malocclusion with a high mandibular plane angle corrected with 2-phase treatment

A 10-year-old girl with maxillary protrusion and crowding of the maxillary and mandibular anterior teeth was treated in 2 phases. In the first phase of treatment, maxillary anterior growth was restrained and mandibular anterior growth promoted for skeletal improvement. In the second phase, at age 13, 4 first premolars were extracted, and an edgewise appliance was used for alveolar improvement. Because the patient had a high mandibular plane angle with a large Frankfort-mandibular plane angle, special care was taken from the beginning to prevent mandibular clockwise rotation. The Frankfort-mandibular plane angle decreased 3.1 degrees at posttreatment. In addition to the skeletal changes, we obtained a favorable lateral profile. This was achieved by the alveolar changes from the lingual movement of the maxillary and mandibular anterior teeth, and the anterior growth of the nasal apex region. The occlusion was stable at the 38-month postretention follow-up.

Stability After Bilateral Sagittal Split Osteotomy Advancement Surgery With Rigid Internal Fixation: A Systematic Review

The purpose of this systematic review was to evaluate horizontal relapse and its causes in bilateral sagittal split advancement osteotomy (BSSO) with rigid internal fixation of different types. A search of the literature was performed in the databases PubMed, Ovid, Cochrane Library, and Google Scholar Beta. From 488 articles identified, 24 articles were finally included. Six studies were prospective, and 18 were retrospective. The range of postoperative study records was 6 months to 12.7 years. The short-term relapse for bicortical screws was between 1.5% and 32.7%, for miniplates between 1.5% and 18.0%, and for bioresorbable bicortical screws between 10.4% and 17.4%, at point B. The long-term relapse for bicortical screws was between 2.0% and 50.3%, and for miniplates between 1.5% and 8.9%, at point B. BSSO for mandibular advancement is a good treatment option for skeletal Class II, but seems less stable than BSSO setback in the short and long terms. Bicortical screws of titanium, stainless steel, or bioresorbable material show little difference regarding skeletal stability compared with miniplates in the short term. A greater number of studies with larger skeletal long-term relapse rates were evident in patients treated with bicortical screws instead of miniplates. The etiology of relapse is multifactorial, involving the proper seating of the condyles, the amount of advancement, the soft tissue and muscles, the mandibular plane angle, the remaining growth and remodeling, the skill of the surgeon, and preoperative age. Patients with a low mandibular plane angle have increased vertical relapse, whereas patients with a high mandibular plane angle have more horizontal relapse. Advancements in the range of 6 to 7 mm or more predispose to horizontal relapse. To obtain reliable scientific evidence, further short-term and long-term research into BSSO advancement with rigid internal fixation should exclude additional surgery, ie, genioplasty or maxillary surgery, and include a prospective study or randomized clinical trial design with correlation statistics.

Comparison of treatment outcomes between skeletal anchorage and extraoral anchorage in adults with maxillary dentoalveolar protrusion

The goal of this retrospective cephalometric study was to compare orthodontic outcomes in patients with maxillary dentoalveolar protrusion malocclusion treated with extraoral headgear or mini-implants for maximum anchorage. Forty-seven subjects with Angle Class II malocclusion or Class I bimaxillary dentoalveolar protrusion were treated by retracting the maxillary dentoalveolar process by using the extraction space of the bilateral maxillary first premolars. Two anchorage systems were used. Group 1 (n = 22) received traditional anchorage preparation with a transpalatal arch and headgear; group 2 (n = 25) received mini-implants (miniplates, miniscrews, or microscrews) for bony anchorage. Pretreatment and posttreatment lateral cephalograms were superimposed to compare the following parameters between groups: (1) amount of maxillary central incisor retraction, (2) reduction in maxillary central incisor angulation, (3) anchorage loss of the maxillary first molar, (4) movements of the maxillary central incisor and first molar in the vertical direction, and (5) changes in skeletal measurements representing the anteroposterior and vertical jaw relationships. The skeletal anchorage group had greater anterior tooth retraction (8.17 vs 6.73 mm) and less maxillary molar mesialization (0.88 vs 2.07 mm) than did the headgear group, with a shorter treatment duration (29.81 vs 32.29 months). Translational movement of the incisors was more common than tipping movement, and intrusion of the maxillary dentition was greater, in patients receiving miniplates than in those receiving screw-type bony anchorage, resulting in counterclockwise rotation of the mandible and a statistically significant decrease in the mandibular plane angle. Cephalometric analysis of skeletal measurements in patients with low to average mandibular plane angles showed no significant difference between groups, although greater maxillary incisor retraction and less mesial movement of the first molar were noted in the mini-implant group. In patients with a high mandibular plane angle, those receiving skeletal anchorage had genuine intrusion of the maxillary first molar and reduction in the mandibular plane angle, whereas those receiving headgear anchorage had extrusion of the maxillary first molar and an increase of mandibular plane angle. In contrast to the posterior movement in the headgear group, anterior movement of Point A was noted in the mini-implant group. In both the anteroposterior and vertical directions, skeletal anchorage achieved better control than did the traditional headgear appliance during the treatment of maxillary dentoalveolar protrusion. Greater retraction of the maxillary incisor, less anchorage loss of the maxillary first molar, and the possibility of counterclockwise mandibular rotation all facilitated the correction of the Class II malocclusion.

Class II malocclusion treated by combining a lingual retractor and a palatal plate

In this article, we describe the treatment of a woman, aged 25 years 8 months, with a Class II malocclusion, severe anterior protrusion, and a high mandibular plane angle. The treatment plan consisted of extracting both maxillary first premolars and mandibular second premolars. En-masse retraction of the 6 maxillary anterior teeth was performed with a lingual approach combining a C-lingual retractor and a C-palatal plate (C-plate). However, the mandibular dentition was treated with conventional labial fixed appliances. After the maxillary anterior retraction, labial fixed appliances were placed on the maxillary dentition only during the finishing stage. Correct overbite and overjet, facial balance, and improved lip protrusion were obtained. The active treatment period was 17 months, and the results were stable for 13 months after debonding. This C-lingual retractor and C-plate combined retraction method can be effective for intrusive retraction of the anterior teeth.

Longitudinal Intermaxillary Relationships in Class III Malocclusions with Low and High Mandibular Plane Angles

To analyze the sagittal, vertical, and transverse relationships of the maxilla and mandible in Japanese girls with Class III malocclusions with different inclination of mandibular plane. This longitudinal study utilized serial posteroanterior and lateral cephalograms of 56 untreated subjects from the age of 8 years until the age of 14 years (low mandibular plane angle group: n = 20; average mandibular plane angle group: n = 15; high mandibular plane angle group: n = 21). Sagittal and vertical growth was analyzed on the basis of lateral cephalograms, and transverse growth was analyzed on the basis of posteroanterior cephalograms. There was no significant difference in intermaxillary sagittal relationships among the three groups from age 8 until 14. On the other hand, there were significant changes in the vertical and transverse intermaxillary relationships during this period. When comparing the three groups at the same age, there were significant differences in vertical and transverse intermaxillary relationships in some ages, whereas no significant difference was found in sagittal relationships in any ages. The inclination of mandibular plane might play a role in anticipating changes in vertical and transverse intermaxillary relationships from 8 until 14 years of age.

Effects of treatment with a combined maxillary protraction and chincap appliance in skeletal Class III patients with different vertical skeletal morphologies

Several cephalometric studies and case reports have described the effects of treatment with a maxillary protraction appliance (MPA) and chincap appliance. The purpose of this investigation was to identify differences in the response to treatment with a combined MPA and chincap in skeletal Class III patients with different vertical skeletal morphologies: short- (low mandibular plane angle) and long- (high mandibular plane angle) face types. The cephalograms used in this study were of 42 Japanese girls at the beginning of treatment (T0, mean age 10.1 years) and at removal of the appliance (T1, mean age 11.5 years). The subjects were divided into two groups (short and long face) according to the inclination of the mandibular plane at T0. Total anterior face height, upper and lower face height, occlusal plane, and gonial angle were significantly larger in the long-face group at T0. In both groups, significant increases in SNA, maxillary size (A'-Ptm'), and ANB were noted during treatment. Compared with the long-face group, the short-face group showed greater forward displacement and size increment of the maxillary body, while there were no significant differences in changes in mandibular size or position between the two groups. These results indicate that the vertical dimensions of the craniofacial skeleton are important factors in the orthopaedic effects of a MPA and chincap and the prognosis for skeletal Class III patients.

Dental Arch Widths and Mandibular-Maxillary Base Width in Class III Malocclusions with Low, Average and High MP-SN Angles

To analyze the development of the dental arches and skeletal mandibular-maxillary bases in untreated Class III malocclusions with low averages and high mandibular plane angles in subjects aged 10 to 14. The records of 50 untreated Japanese girls with Class III malocclusions at age 10 were selected from the files of patients pending orthodontic surgery. The patients included those with low (< or =27 degrees), average (27 degrees through 37 degrees) and high (>37 degrees) mandibular plane angles. The maxillary skeletal base width, biantegonial width, and maxillary and mandibular intermolar width were determined on posteroanterior cephalograms obtained at annual intervals when subjects were between 10 and 14 years of age. The difference between the maxillary and mandibular intermolar width was also calculated and reported. All skeletal and dental transverse widths in the high-angle group were significantly smaller than those in the low-angle group (P < .05) from ages 10 to 14. On the other hand, the maxillary to mandibular molar difference was the same for the three groups (P > .05) at each age. The deviations in molar differences did increase from age 10 to age 14 in all three groups. Mandibular plane angles might play a stronger role in the transverse skeletal growth of the maxilla and the mandible than the transverse dental growth of the maxilla and the mandible.

Category 5: Class II Division 1 malocclusion with a high mandibular plane angle

This case report was submitted to the American Board of Orthodontics as part of the board-certification process. The summary of treatment and records are reprinted here much as they were submitted to the board.

Transverse growth of the maxilla and mandible in untreated girls with low, average, and high MP-SN angles: A longitudinal study

The purpose of this study was to investigate maxillary and mandibular transverse growth in untreated female subjects with low, average, and high mandibular plane angles longitudinally from ages 6 to 18. Eighty-one untreated white girls with low (< or = 27 degrees , n = 16), average (> 27 degrees to < 37 degrees , n = 41), and high (> or = 37 degrees , n = 24) mandibular plane angles at age 6 were selected from the Bolton-Brush and Burlington Growth Studies. For each subject, longitudinal posteroanterior cephalograms at different ages (from ages 6 to 18) were traced, and the widths of maxilla and mandible were measured. All the measurements were converted by using a magnification factor of 8.5% (the subject-to-film distance was set at 13 cm). At age 6, the high-angle group had narrower maxillary and mandibular widths than the low-angle group, and this trend continued until age 18. From ages 6 to 14, maxillary width showed a steady and similar rate of increase for all 3 groups (0.90-0.95 mm per year), yet a plateau was reached at age 14 for all groups. Mandibular width increased at a steady rate (about 1.6 mm/year) for all 3 groups until age 14, and a plateau was reached for the high-angle group. For the low- and average-angle groups, mandibular growth continued from ages 14 to 18 but at a slower rate (0.85 mm and 0.39 mm per year, respectively). Vertical facial patterns (with low or high mandibular plane angles) might play a strong role in the transverse growth of the maxilla and the mandible.

Commentary to “The influence of the sagittal split osteotomy on the condylar cartilage structure and the subchondral vascularization of the temporomandibular joint: A preliminary study in goats”

Progressive condylar resorption (PCR) (or condylysis) is a mysterious malady that can occur spontaneously without intervention or can occur after orthodontic and/or surgical intervention to correct malocclusions. We know very little about this process. It has been demonstrated more commonly in patients who have high mandibular plane angles. What is unclear, however, is whether such individuals are simply more susceptible to this process or whether they already have been afflicted by the process and are prone to progression of the process. It is very possible that these individuals might have high mandibular plane angles because they have already had some condylar resorption early in life.

Cephalometric Evaluation for Saudi Population Using the Downs and Steiner Analysis

The purpose of this study is to formulate cephalometric norms of the Saudi population; and to evaluate whether significant cephalometric differences exist between Saudi and Caucasian patients. Lateral cephalometric radiographs of 60 selected Saudis (30 males and 30 females) with esthetically pleasing and harmonious faces, Angle I molar relationship, with all permanent teeth present and no history of orthodontic treatment or facial trauma, age range between 20 and 30 years were analyzed using the Downs and Steiner analysis. The means, standard deviations, and ranges of the measurements were compared with the norms established by Downs and Steiner. Statistically, several significant differences were noticeable in the results of the present study when the cephalometric mean values for the selected Saudi population were compared with the norms suggested for a white Caucasian population by Downs and Steiner. The results of the present study are significant and showed normal Saudis have a slightly protrusive maxillae, a tendency to Class II facial pattern, and a high mandibular plane angle. These results have clinical implications in the diagnosis and treatment of adult Saudis with dentofacial deformities.