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[Relation between atlas position, prognathism and prognathous jaw anomalies].

The position of the 1st cervical vertebra is investigated in relation to special anomalies of the craniofacial morphology. Two extremely different types like prognathism and progenia are chosen to demonstrate an interdependence. The latter is probably caused by a different head posture which in itself is influenced by the maxillo-facial anomalies. With the aid of the literature the findings can be explained on a functional basis.

Adolescent↗
PubMed1980

[The effect of prognathism surgery on the temporomandibular joint. (A clinical and radiological evaluation of temporomandibular joint changes after various methods of surgery for prognathism)].

On the basis of clinical and roentgenologic examinations of progenia patients which were planned according to our occlusal concept and monitored postoperatively, we established that the condylar displacement in the roentgenogram offers an exact parameter for the extent of operative displacement of the condyles. Nevertheless, a direct conclusion concerning the clinical symptoms or freedom of complaints cannot be established on the basis of this roentgenographic analysis. The roentgenogram also showed considerable condylar alterations in patients with temporomandibular joint symptoms; greater displacement of the condyles was frequently demonstrable with temporomandibular joint complaints.

Humans↗
PubMed1999

Temporomandibular joint symptoms and disc displacement in patients with mandibular prognathism.

Our objective was to find out the incidence of signs and symptoms of temporomandibular joint (TMJ) and disc displacement in patients with mandibular prognathism. Fifty-one patients were examined clinically and by axial computed tomography(CT). The incidence of TMJ signs and symptoms was 6/25(24%) in patients with simple mandibular prognathism and 12/26(46%) in patients with mandibular prognathism and asymmetry. No discs were displaced in patients with simple mandibular prognathism, but 15(58%) of the patients with mandibular prognathism and asymmetry had displaced discs. There was no association between signs and symptoms of TMJ and disc displacement. Patients with mild protrusion and severe asymmetry of the mandible had a high incidence of disc displacement, which interestingly was on the deviated side in 14 of the 15 patients affected. We conclude that skeletal morphology may have a role in the development of TMJ disorders but the mechanism is obscure.

Adolescent↗
PubMed2004

Computer-assisted morphological analysis of dental casts with maxillary prognathism and reversed occlusion.

The morphologic characteristics of the dentition with maxillary prognathism and reversed occlusion were examined by a computer-assisted dental cast analysing system. Dental casts with normal occlusion, maxillary prognathism and reversed occlusion were selected and measured by a 3D shape measuring system. The dental arches and anteroposterior occlusal curves were approximated numerically by the polynomial expression with a fourth order and second order coefficients, respectively. The coefficients were analysed statistically. Maxillary dental arches with mandibular prognathism showed a more acuminate shape (V-shape) with a significant larger second order coefficient, while arches with reversed occlusion showed more angulate shapes (U-shape) with significantly smaller second order coefficients compared with arches with normal occlusions. However, a notable difference in the shape of the mandibular dental arches was not observed. The mandibular dental arches with maxillary prognathism were positioned backward relative to maxillary dental arches, while the arches with reversed occlusion were positioned forward. The anteroposterior occlusal curves with maxillary prognathism showed larger curvatures in maxilla and mandible, while the curves with reversed occlusion showed smaller curvatures in mandible comparing with the curves with normal occlusion. These results suggest that the present method could offer a useful and objective examination technique for the diagnosis of malocclusion.

Adolescent↗
PubMed1999

Stability after sagittal split ramus osteotomy without post-operative maxillomandibular fixation in the treatment of prognathic patients with asymmetric mandibles.

OBJECTIVE: To examine post-operative stability in prognathic patients with mandibular asymmetry who underwent sagittal split ramus osteotomy (SSRO) of the mandible and titanium screw fixation without post-operative maxillomandibular fixation (MMF). DESIGN: Skeletal and dental changes after surgery with and without post-operative MMF were compared between prognathic patients with symmetric and asymmetric mandibles. SETTING AND SAMPLE POPULATION: Second Department of Oral and Maxillofacial Surgery at Tokyo Medical and Dental University. Twenty prognathic patients were examined. EXPERIMENTAL VARIABLE: An appliance for repositioning the proximal segment was applied in all 20 patients. Ten patients with symmetric mandibles received post-operative MMF with stainless steel wires and intermaxillary rubber traction after the removal of MMF (Group I), while the other 10 patients with asymmetric mandibles underwent post-operative intermaxillary rubber traction only (Group II). OUTCOME MEASURE: Posteroanterior cephalograms were obtained pre-operatively; 2-3 days post-operatively; and 3, 6, and 12 months after surgery. Changes in the positions of the gonion points (Go) and upper and lower incisors (U-1 and L-1) were examined. RESULTS: In both groups, the Go tended to shift laterally as a consequence of the operation. Although the tendencies of the post-operative changes in the Go points of Groups II and I were different, statistical analyses revealed no significant differences between the two groups. At the last stage of the follow-up period, the absolute value of the change in L-1 tended to be larger in Group II than in Group I, but without any statistical significance. CONCLUSION: This study suggests that post-operative change in prognathic patients with asymmetric mandibles treated without post-operative MMF is comparable to that in patients with symmetric mandibles treated with post-operative MMF. Accordingly, post-operative MMF may be avoided, even in prognathic patients with asymmetric mandibles.

Adolescent↗
PubMed1977

Differential treatment planning for mandibular prognathism.

The treatment records of thirty-eight cases of mandibular prognathism treated by orthodontics means only (ORTHO) were evaluated. The pretreatment records of twenty cases of mandibular subapical esteotomy (SUB) and twenty cases of mandibular setback (SET) were evaluated for comparison and contrast with the pretreatment ORTHO records and with each other. Dental, skeletal, and soft-tissue parameters in the vertical and horizontal planes of space were recorded. Statistical analysis of means of parameters of the pretreatment records provided documentation of the discriminant variables in each of the following paired groups: ORTHO-SUB, ORTHO-SET, and SUB-SET. Analysis of the data as indicated above led to the following conclusions: 1. Three discriminant groups of mandibular prognathism of various degrees of severity were discernible when comparisons of treatment categories simulating clinical decisions were made. The ORTHO group was distinguished from the SUB group in the horizontal plane and, more strongly, in the vertical plane. The ORTHO group was distinguished from the SET group in the vertical plane and, more strongly, in the horizontal plane. The SUB group was distinguished from the SET group in the horizontal plane. 2. The physiologic developmental status of the patient should be carefully evaluated. 3. Anteroposterior dysplasias should be assessed relative to the cant of the mandibular plane. True denture base discrepancies can be noted relative to the occlusal plane. 4. Documentation of vertical dysplasias should include measurements of craniofacial divergence (SN-MP, FH-MP, and OP-MP). 5. In assessing the profile evaluation of the patient with mandibular prognathism, particular attention should be focused on facial contour angle (FCA), nasolabial angle (NLA), and relative lower lip protrusion (LLP). 6. Any numerical values obtained in the evaluation of the dental, skeletal, or soft-tissue characteristics of mandibular prognathism should be considered only as descriptive, diagnostic guides and not as components of a diagnostic formula.

Alveolar Process↗
PubMed1977

Tooth-size discrepancy in mandibular prognathism.

A Bolton analysis of seventy-eight cases of Angle Class III malocclusion, twenty-six cases of Angle Class I malocclusion, and twenty-six cases of Angle Class II malocclusion was recorded. Frequency of excess mandibular tooth structure, magnitude of the excess, over-all ratios, and anterior segment ratios were computed and analyzed. Two clinical cases were presented to show the advantage of tooth-size harmony in mandibular prognathism. Analysis of the data as presented above suggests the following conclusions: 1. The frequency of mandibular tooth-size excess (over-all ratio) in this sample was greater in cases of mandibular prognathism than in Angle Class I and Angle Class II cases. 2. In those cases with mandibular tooth-size excess, there was a suggestion that the magnitude of the excess was greater in cases of mandibular prognathism than in Angle Class I and Angle Class II cases. 3. A tooth-size discrepancy analysis should be included as one part of the diagnostic records for mandibular prognathism.

Adolescent↗
PubMed2004

Transitional joint effusion in the mandibular prognathic surgery patient: intraoral vertical ramus osteotomy versus sagittal split ramus osteotomy.

PURPOSE: The purpose of this study was to examine the cause of joint effusion (JE) appearing postoperatively in the temporomandibular joint (TMJ) of patients with mandibular prognathism on T2-weighted magnetic resonance (MR) images. PATIENTS AND METHODS: MR imaging was performed before and after surgery in 30 TMJs of 15 subjects with mandibular prognathism who underwent intraoral vertical ramus osteotomy (IVRO) and in 20 TMJs of 10 subjects with mandibular prognathism who underwent sagittal split ramus osteotomy (SSRO). The preoperative MR imaging was performed 1 month before surgery, and postoperative MR imaging was performed during maxillomandibular fixation. RESULTS: Preoperatively, none of SSRO and IVRO groups had JE. Postoperatively, 12 TMJs (40%) of the IVRO group and only 1 TMJ (5%) of the SSRO group had JE. As for the TMJs in the IVRO group, on MR imaging, the degree of downward movement of the condyle after surgery was larger in TMJs with JE (3.8 +/- 2.3 mm) than in TMJs without JE (1.8 +/- 1.6 mm). JE diminished within about 4 months after removal of the maxillomandibular fixation. CONCLUSION: JE appearing postoperatively in the TMJ of patients with mandibular prognathism might be relation to the degree of downward movement of the condyle.

Adolescent↗
PubMed1993

Growth of mandibular prognathism after pubertal growth peak.

This study deals with the growth changes of the Japanese face associated with mandibular prognathism during 3 years after the pubertal growth peak. The investigation was based on the serial lateral cephalometric roentgenograms of prognathic and normal males and females, respectively. Maturational stages of the pubertal growth were determined individually by the ossification events taken from hand-wrist radiographs. Results indicate that the morphologic characteristics of the mandibular prognathism, which are established before the pubertal growth peak, are strongly maintained during the period studied. However, mandibular prognathism seems to show a manner of growth change fairly similar to that of the normal after the pubertal growth peak.

Adolescent↗
PubMed1993

Morphologic and functional implications of the surgical-orthodontic management of mandibular prognathism: a comprehensive review.

The aim of this review is to present the various morphologic and functional implications of the surgical-orthodontic management of mandibular prognathism, thus providing a more complete determination of the efficacy of this modality of treatment. Major conclusions that can be drawn from the bibliography indicate that: (1) After treatment considerable improvement takes place on the soft tissue and dentoskeletal profile, occlusal tooth contacts, and temporomandibular joint function and and pain; (2) Surgical management of mandibular prognathism can be associated with decreased maximum interincisal opening; (3) Although immediately after surgery there is a tendency for the condyles to be distracted downward and anteriorly from their preoperative position, in long-term postsurgery the condyles, on the average, regain their initial position; (4) Compensatory alterations in the pharyngeal, suprahyoid, and infrahyoid muscular regions take place postoperatively; (5) Skeletal changes after mandibular setback to correct mandibular prognathism occur frequently, but their magnitude and patterns exhibit variation and are not necessarily detrimental; and (6) Fulfillment of expectations toward surgical-orthodontic management of mandibular prognathism was reported to be frequent.

Bite Force↗
PubMed2000

Three-dimensional morphology of the masseter muscle in patients with mandibular prognathism.

OBJECTIVE: To compare the morphology of the masseter muscle in patients with mandibular prognathism with that of normal subjects. METHODS: Three-dimensional X-ray computed tomography (CT) was performed on 69 patients with mandibular prognathism and compared with 91 normal subjects. The angle of the muscle direction in relation to the Frankfurt horizontal plane and the area and the ratio of length of the short to long axes (s/l ratio) on the section perpendicular to the muscle direction were measured. RESULTS: The mean angle, area and s/l ratio in patients with mandibular prognathism was 76.6 degrees (s.d. 4.4 degrees), 318.3 mm2 (s.d. 77.2 mm2) and 0.312 (s.d. 0.049), respectively. Those of the normal subjects were 65.1 degrees (s.d. 4.4 degrees), 368.3 mm2 (s.d. 97.2 mm2) and 0.393 (s.d. 0.054), respectively. The angle was significantly larger, and the area and s/l ratio were significantly smaller than those of normal subjects (P < 0.001). CONCLUSION: The morphology of the masseter muscle in mandibular prognathism is significantly different from that of normal subjects. Our results may be helpful in evaluating the results of orthognathic surgery.

Adolescent↗
PubMed1996

Surgical refinement of the operative procedure for a minor degree of mandibular prognathism.

Although sagittal splitting ramus osteotomy is used widely for mandibular prognathism and even for that of a minor degree, a long duration of preoperative and postoperative orthodontic treatment is required. Conversely, mandibular segmental osteotomy has often been used to correct a minor degree of mandibular prognathism without specific orthodontic treatment. Here we describe a surgical refinement accomplishing mandibular segmental osteotomy, reduction genioplasty by double horizontal osteotomies, and decortication of the middle portion of the osteotomies for a minor degree of mandibular prognathism. The amount of setback is limited to 4 to 5 mm, no intermaxillary fixation is required, and no orthodontic treatment, in principle, is needed. This procedure can obtain a rapid aesthetic improvement. We used this procedure in 11 patients (7 females and 4 males) with a minor degree of mandibular prognathism. The amount of setback of the mandibular anterior portion was 4 to 5 mm, and satisfactory results were obtained in all patients.

Adolescent↗
PubMed1996

Tongue volume in human female adults with mandibular prognathism.

It has often been hypothesized that a large tongue leads to an enlargement of the mandible and therefore contributes to the development of mandibular prognathism. We examined (1) whether the tongue volume in human subjects with mandibular prognathism was larger than that in subjects with good occlusion and (2) whether the tongue volume and the pharyngeal capacity correlated with the morphological characteristics of dento-skeletal structures. Magnetic resonance images of the tongue and its surrounding structures were recorded for female adult volunteers with good occlusion (control group, n = 10) and patients with mandibular prognathism (test group, n = 16). Lateral cephalograms were obtained for the patients. No significant differences were determined for the tongue volume or the pharyngeal capacity between the two groups. The tongue volume did not correlate with the pharyngeal capacity (r = 0.280, p = 0.166). The tongue volume correlated with the facial angle (r = 0.548, p = 0.028), the Y-axis (r = 0.539, p = 0.031), and the angle nasion-A point-pogonion (r = 0.540, p = 0.031). These results suggest that the tongue volume is accounted for by the combined horizontal and vertical location of the chin and symphysis, but do not support the conventional clinical surmise that large tongue volume is inherent in patients with mandibular prognathism.

Adult↗
PubMed2003

Segregation analysis of mandibular prognathism in Libya.

The etiology of mandibular prognathism has been attributed to various genetic inheritance patterns and some environmental factors. The variation in inheritance patterns can be partly due to the use of different statistical approaches in the respective studies. The objective of this study was to investigate the role of genetic influences in the etiology of this trait. We performed segregation analysis on 37 families of patients currently being treated for mandibular prognathism. Mandibular prognathism was treated as a qualitative trait, with cephalometric radiographs, dental models, and photographs used to verify diagnosis. Segregation analysis of a prognathic mandible in the entire dataset supported a transmissible Mendelian major effect, with a dominant mode of inheritance determined to be the most parsimonious.

Adult↗