Submentovertex Radiographs Research Articles

Evaluation on the use of plate positioning guide (PPG) on the placement accuracy of post-hemimandibulectomy plate reconstruction

Improper placement of the reconstruction plate can lead to postoperative complications. Placing reconstruction plates that have arch for operation is made easier with the plate positioning guide (PPG) as a transfer method of reconstruction plate. This study aimed to assess the impact of PPG on the placement accuracy of reconstruction plate as determined by the symmetrical breadth of the mandibular arch and the consistent placement of reconstruction plate following hemimandibulectomy. According to the inclusion criteria, this was a retrospective cross-sectional study with 12 participants (n = 12) after hemimandibulectomy. Subjects were divided into PPG (n = 6) and Non-PPG (n = 6) groups. Measurement of the difference in the width of the mandibular arch and the height of the placement of the reconstruction plate between the reconstructed and non-resected sides in three positions (anterior, posterior, and angulus) was conducted using submentovertex radiographs and orthopantomogram (OPG) through the RadiAnt DICOM Viewer software. The placement accuracy of the reconstruction plates was analyzed using a one-sample t-test with p-value 0.05. The results showed that the placement accuracy of the reconstruction plate in the PPG group were accurate (p = 0.590), and the Non-PPG group was inaccurate (p = 0.000); with the independent sample test. There was a significant difference between the two groups (p = 0.000). Plate positioning guide provides better symmetry of the mandibular arch width post-hemimandibulectomy.

Is Ultrasonography Efficient for the Detection of the Zygomatic Arch, Nasal Bone and Cartilage Fractures?

Background: The high incidence of nasal and zygomatic arch fractures highlights the need for an accurate imaging modality for their detection. The superimposition of structures is a major problem in conventional radiography. Ultrasonography is a low-cost imaging modality with a wide range of applications, that does not employ ionizing radiation. This study aimed to assess the efficacy of ultrasonography for the detection of the zygomatic arch and nasal bone fractures. Materials and Methods: This study was conducted on 16 sheep heads. Artificial fractures were created in some parts of the zygomatic arch, dorsum and lateral wall of the nose, and nasal cartilage. All sheep heads underwent Cone-Beam Computed Tomography (CBCT) to ensure the presence of a fracture. Next, the lateral nasal and submentovertex radiographs were obtained, and ultrasonography was performed with a 12-15 MHz linear probe. Ultrasonography and radiography were repeated after 1 week to assess their reproducibility by calculating the kappa coefficient. Data were analyzed using Stata 11 software and Chi-square test. Results: The specificity and sensitivity of ultrasonography ranged from 87% to 100%, and 50% to 75%, respectively. The specificity and sensitivity of radiography ranged from 87% to 100%, and 62% to 87%, respectively. The differences between the two imaging modalities were not statistically significant (p>0.05). The kappa coefficient ranged from 46% to 100% for ultrasonography and 44% to 87% for radiography. Conclusion: Ultrasonography seemed useful for the detection of displaced bone and cartilage fractures. For non-displaced fractures, US is not recommended.

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

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

Does The Titanium Plate Fixation of Symphyseal Fracture Affect Mandibular Growth?

The effect of metallic fixation on growth is a major concern in children and is not yet clear. The aim of this study was to evaluate the effect of metallic fixation of mandibular symphyseal fracture on mandibular growth.Eighteen 90-day-old growing white New Zealand rabbits weighing 1.6 to 2.5 kg were included in this study and divided into 2 groups of 9 subjects. In the experimental group, animals underwent mandibular osteotomy, simulating a symphyseal fracture on the midline of mandibular symphysis. The bone segments were fixed with microplates and microscrews (1.6 mm).In the control group, the same surgical incision without performing symphyseal osteotomy was conducted, and 2 screws were inserted on each side of the symphyseal midline.Digital cephalometric and submentovertex radiographs were taken before the operation and at postoperative 6 months for each animal in 2 groups, and cephalometric measurements were performed. The distance between the centers of the head of 2 screws measured at the end of surgery in the control group was compared with measurements at 6 months after surgery. Obtained data were statistically analyzed.There is no statistically significant difference between the 2 groups for growth amount of both sides of the mandible. Difference of ANS-Id (the most anterior points of nasal bone, the most anterior point on the alveolar bone between the lower incisors) and Cd-Id (the uppermost and most distal point of the mandibular condyle, the most anterior point on the alveolar bone between the lower incisors) values of the 2 groups is not statistically significant (P > 0.05).The distance between the 2 screws at the first application significantly increased at the postoperative sixth month (P < 0.05). Metallic fixation of mandibular symphyseal fracture does not affect the vertical and sagittal mandibular growth in growing rabbits.

下顎枝矢状分割法が下顎頭の位置と顎関節症状に及ぼす影響について―３種類の術式の比較―

This study investigates the effects of sagittal split ramus osteotomy (SSRO) on condylar position and temporomandibular joint (TMJ) symptoms.The subjects were 51 patients (13 males and 38 females) in whom mandibular protrusions were corrected by SSRO; they were divided into three subtypes on the basis of the lateral bone cut location. The joints were examined clinically for pain, sound and maximum interincisal opening before surgery and at least six months after surgery. Submentovertex radiographs were taken before and immediately after surgery. The changes in condylar position were assessed by measuring the condylar angle, intercondylar axes angle and distance between the centers of the condyles.After SSRO, the condyles rotated inward (p < 0.01) on the axial plane, but the distances between their centers did not change significantly. TMJ signs and symptoms disappeared in four (31%) of the 12 symptomatic patients, worsened in one (8%) of the symptomatic patients and developed in three (8%) of the 39 asymptomatic patients six months after surgery. There were no significant differences in any of the parameters among the three subtypes of SSRO.

Effects of Titanium Plate Fixation on Mandibular Growth in a Rabbit Model

The purpose of this study was to evaluate the effect of metallic rigid fixation of mandibular corpus fracture on mandibular growth in growing rabbits. Thirteen 90-day-old white New Zealand rabbits weighing 2 to 2.6 kg were included in this study. Unilateral mandibular fractures were created in all of the animals and fixed with microplates and screws. Microplates that had been adapted for fixation of the left (experimental) side were also used as a template for the drilling procedure on the right (control) side of the mandible. The plate was then removed, and screws were inserted. Digital submentovertex radiographs of each animal were taken before the operation and 6 months after surgery. Cephalometric values were analyzed. The distance between the centers of the 2 screws on the right side of the mandible was measured with a caliper in all samples, and values were compared with measurements taken from the left (experimental) side of the mandible upon which the plates had been placed. The mean amount of mandibular growth was 4.38+/-2.43 mm on the right (control) side and 4.64+/-2.27 mm on the left (experimental) side. This difference was not statistically significant (P> .05). The distance between the 2 screws was 13.89+/-0.23 mm on the experimental side and 13.44+/-0.46 mm on the control side. This difference was statistically significant (P< .05). Metallic fixation of a mandibular body fracture did not cause mandibular asymmetry or restricted mandibular growth in growing rabbits in this relatively small sample.

Tridimensional Evaluation of Maxillary and Mandibular Movements in Orthognathic Surgery

For better evaluation of long-term results of orthognathic surgery, movements of osteotomized maxillary and mandibular segments should be documented both in x-, y-, and z-axes and in terms of kind of movement (either linear or rotational movements). Lateral cephalometric, anteroposterior cephalometric, and submentovertex radiographs of 14 patients, treated with combined orthodontic and surgical treatment for skeletal class III malocclusion, were reevaluated retrospectively to demonstrate the applicability and usefulness of defined parameters in four maxillary and five mandibular movements. There was no clinically significant relapse in the follow-up period of 6 months in any of the patients. Differences between preoperative and postoperative measurements to demonstrate the linear movement in the z-axis, rotational movements in the x-axis and y-axis of the maxilla, and the linear movement in the z-axis of the mandibula were found to be statistically significant. Differences between early postoperative and late postoperative measurements to demonstrate rotational movement in the y-axis of the maxilla and rotational movement in the y-axis of the mandibula were found to be statistically significant. In this article, the possible tridimensional movements and cephalometric measurements of osteotomized bony segments after LeFort I and sagittal split osteotomy surgery were defined for better evaluation and follow up of the postoperative results.

Submentovertex cephalometric norms in Turkish adults

The aims of this study were (1) to establish cephalometric norms from submentovertex (SMV) radiographs for young Anatolian Turkish adults and (2) to identify possible sex differences between men and women. SMV cephalograms were taken of 50 nongrowing Turkish adults (25 men, mean age, 23.06 +/- 2.30 years; 25 women, mean age, 22.10 +/- 2.04 years). All had normal occlusions and well-balanced faces. Five angular and 10 linear measurements were made on each radiograph. For each variable, arithmetic mean and standard deviation minimum and maximum values were calculated. Independent-sample t tests were performed for the sex comparisons. Cephalometric angular and linear norms for Turkish adults were determined by using the Lew-Tay SMV cephalometric analysis. SMV cephalometric standards for Turkish adults were also developed. Generally, our measurements were similar to the Lew-Tay SMV norms. Most Turkish SMV cephalometric measurements showed statistically significant sex differences. Comparison between Turkish men and women indicated larger measurements for men in all investigated linear measurements. SMV cephalometric norms are useful in the diagnosis of mandibular asymmetries and the treatment of dentofacial orthopedics in Turkish patients.

The effect of head rotation on cephalometric radiographs

The aim of this study was to identify the potential projection errors of lateral, postero-anterior (PA) and submentovertex (SMV) cephalometric radiographs due to head rotation in the vertical z-axis. For this investigation, a complete human dry skull of an adult was used. The skull was rotated from 0 to +/-14 degrees at 2 degree intervals. A vertical axis, the z-axis, was used as the rotational axis to expose 15 lateral and 15 PA cephalometric radiographs. The skull was tilted on each side, again at 2 degree intervals, to expose the 15 SMV films. A series of linear and angular measurements was carried out on all cephalograms. The results revealed that horizontal linear and angular measurements between the horizontal planes on lateral cephalograms were subject to changes from 16.1 to 44.7 per cent with a 14 degree rotation of the head position. For PA cephalograms, again horizontal linear measurements, particularly mandibular length, were subject to a projection error of up to 34.9 per cent with head rotation. On the other hand, projection errors were within the 3-4 per cent limit for SMV radiography. The findings indicate that: (1) linear measurements and the measurement of angles between the horizontal planes are likely to be affected by head rotation in lateral cephalograms, (2) angular measurements demonstrate smaller variations with changing rotation of the head in PA cephalograms, (3) SMV radiographs are less vulnerable to head rotation. Vertical linear measurements of lateral cephalograms and angular measurements of PA radiographs are more reliable in minimizing the projection errors associated with head rotation.

Bone gap healing in the dog using recombinant human bone morphogenetic protein-2

Purpose: This study investigated bone gap healing in a zygomatic arch defect using recombinant human bone morphogenetic protein-2 (rhBMP-2; Genetics Institute, Andover, MA) in an absorbable collagen sponge (ACS) carrier. Methods: Zygomatic arch osteotomies were completed 15 mm apart and the arch was mobilized in 6 adult female mongrel dogs. The segment was then repositioned laterally 8 to 10 mm and secured with a titanium reconstruction plate. Bone gaps in either the right or left arches received rhBMP-2, with the contralateral side being left empty in 4 animals and the defects received buffer/ACS without rhBMP-2 in 2 animals as controls. Submentovertex radiographs were taken immediately postoperatively and every 4 weeks until killing at 12 weeks. Results: Clinical evaluation indicated no significant differences in the degree of inflammation between the groups. However, the rhBMP-2 sites were found to be firm on palpation, in contrast to a soft tissue defect palpated in the control sites. Radiographic examination showed significant bone formation in all rhBMP-2 grafted sites as early as 4 weeks. The radiopacity of the bone continued to increase over the time of this study. Five of six control sites did not show bone formation through the course of this study. In addition to lack of bone formation, 5 of 6 control sites showed collapse of the repositioned arch. All arches in the rhBMP-2 sites remained in their lateral position and formed bone in the gaps. In 2 animals, bone formation moderately exceeded the confines of the gap, and in 2 animals excessive bone formation occurred. Conclusions: This study confirms that rhBMP-2 has the potential to be used to stimulate bone gap healing in the craniofacial complex. © 2000 American Association of Oral and Maxillofacial Surgeons

Mandibular asymmetry and condylar position in children with unilateral posterior crossbite

The purpose of this retrospective study was to determine if condylar position in children with functional unilateral crossbites was different from that found in children with Class I noncrossbite malocclusions and if there was a change in condylar position after correction of the crossbite by palatal expansion. Mandibular asymmetry in children with functional unilateral posterior crossbite was also compared to that of a Class I noncrossbite group. Thirty-one children aged 6 to 14 years (mean, 9.3 years; standard deviation, 2.2) with functional unilateral crossbites were compared to 31 children aged 9.5 to 14.1 years (mean, 11.9 years; standard deviation, 1.3) exhibiting Angle Class I noncrossbite malocclusions. Pretreatment submentovertex radiographs were used to study mandibular skeletal, dental, and positional asymmetries with reference to cranial floor and mandibular coordinate systems. In addition, the anterior, superior, and posterior joint spaces were measured to determine differences between the groups with the use of pretreatment and posttreatment horizontally corrected tomograms of the temporomandibular joints. Finally, the distances of the mesiobuccal cusp of the upper first molar relative to the buccal groove of the lower first molar were measured in both groups before treatment. Univariate analyses revealed that the mandibles of children in the functional unilateral posterior crossbite group exhibited asymmetry in both anteroposterior and transverse dimensions when compared with the Class I noncrossbite group ( P < .05). These asymmetries were the result of a functional deviation of the mandible that was present in all subjects in the crossbite group. This deviation was manifested occlusally by a Class II subdivision on the crossbite side as indicated from the study model analysis ( P < .05). Examination of condylar position as evidenced by horizontally corrected tomograms demonstrated a large standard deviation, resulting in an inability to detect any significant differences within or between groups at both T1 and T2 ( P > .05). This study raised the question of the appropriateness of measuring joint spaces for routine diagnostic purposes. (Am J Orthod Dentofacial Orthop 1999;115:569-75)

Landmark identification error in submentovertex cephalometrics: A computerized method for determining the condylar long axis

The purpose of this study was to examine the identification error of certain submentovertex landmarks and to compare three different methods of determining horizontal condylar angulation in submentovertex radiographs. To determine landmark identification error, a random sampling of 12 submentovertex radiographs from preorthodontic patients between the ages of 10 and 17 years was used to determine both intraexaminer and interexaminer reliability. The error associated with the identification of each of 11 landmarks varied between specific landmarks, between the same landmarks bilaterally, and between the vertical and horizontal components of the same landmark. In general, intraexaminer data showed less landmark identification error in both vertical and horizontal directions than did interexaminer data. The foramen spinosum landmarks demonstrated the lowest identification error in both horizontal and vertical directions (intraexaminer), whereas greater identification error was associated with the condylar lateral poles and posterior condylar points (both intraexaminer and interexaminer). A comparison of three different methods of condylar angulation determination was undertaken through the use of two tracings of each of 101 submentovertex radiographs. A computer-derived method representing the principal axis of minimum moment of inertia of the condyle was shown to be more reliable ( p < 0.05) with respect to describing condylar angulation than both a method that used a best-fit line through the anterior condylar border and an interpolar axis method.

A reliability comparison of submentovertex and zonographic methods of horizontal condylar angle estimation

Objective. The objectives of this retrospective clinical study were, first, to compare submentovertex radiography and zonographic temporomandibular joint orientation programs that use the Scanora imaging system with respect to the reproducibility with which the angulation of the horizontal condylar axis may be determined and, second, to assess the level of agreement between the 2 methods. Study design. Submentovertex radiographs and zonographic projections of 16 joints (8 patients) were evaluated. Two raters independently determined the horizontal angulation of each condyle 3 times using each method. Horizontal condylar angle measurements differing by no more than 5 degrees were considered to be in agreement. Statistical analyses were performed with a repeated-measures analysis of variance, sign tests, and Wilcoxon signed rank test. Results. No significant difference was found in the 3 measurements between the 2 raters ( P = .9122) or between the raters adjusted for method ( P = .5093). A significant difference was found between methods ( P = .0001). Intrarater agreement values were 81% and 88% for the submentovertex method and 75% for each rater for the zonographic method. Interrater agreement was 94% for each method. Intermethod agreement was 50% for one rater and 81% for the other. Conclusions. The submentovertex and zonographic methods of determining the horizontal condylar angulation demonstrated consistency and reliability both within and between the raters. However, the zonographic method did not agree with the submentovertex method. This finding does not imply that the zonographic method is not a clinically acceptable technique for the determination of the horizontal condylar angulation when subsequent tomographic projections are made on the same unit with the same head-positioning device.

軸方向頭部Ｘ線規格写真による下顎頭長軸角の計測方法に関する研究

The purpose of this study was to compare three different methods of measuring angular changes of the mandibular condyle in the horizontal plane. A cephalometer (Model C-166 R: Tokyo Emix Co. Ltd., Japan) along with an apparatus we developed were utilized to obtain submentovertex radiographs. The subjects were placed in a position where the central ray is perpendicular to the Camper plane.In fifteen subjects with normal occlusion, two submentovertex cephalograms were obtained from each individual at two different times with the teeth in centric occlusion. The following are the three different measuring methods:(A) “Best fit” method: The outlines of the condyles were traced and superimposed by the “Best fit” of the condyle. Then the angle between two inter-foramina spinosa lines was measured.(B) “Caliper” method: To determine a condylar long axis by using a sliding digital caliper.(C) “Perpendicular lines” method: The condylar long axis was determined by using tangent perpendicular lines from an inter-foramen spinosum line to the outline of the condyle. The tangents touch the outline of the condylar shape at the outermost point and the innermost point. A straight line that connects these two points is the condylar long axis.The condylar long axis was determined by methods (B) and (C). The angle between the condylar long axis and the inter foramina spinosa line (condylar angle) was measured. Then the difference in the condylar angle between the two films was computed.All films were traced, superimposed, and measured by the same examiner. The results were as follows:1) The error of measurement of condylar rotation by the “Best fit” method was 1.0°±0.9°by the “caliper” method was 2.5°±2.1°and by the “perpendicular lines method” was 1.9°±1.5°Statistically significant (p<0.01) differences were found when the “Best fit” method was compared with the other two methods.2) The condylar angle measured with the caliper was 15.7°±8.4°and with the perpendicular lines method was 10.1°±5.4°Statistically significant (p<0.01) differences were found between the two methods as determined by the t-test.In conclusion, (1) the “Best fit” method was more suitable for measuring condylar rotation than the other conventional methods.(2) The “caliper” method of measuring the condylar angle in the horizontal plane was more suitable than the method using perpendicular lines.

An evaluation of mandibular asymmetry in adults with unilateral posterior crossbite

A retrospective study was conducted to determine whether mandibular symmetry in adults with untreated unilateral posterior crossbite was different from that found in adults with untreated Class I malocclusions. Thirty adults, 18 years or older, with a unilateral posterior crossbite were compared with 30 adults exhibiting Angle Class I malocclusions. Skeletal and dental symmetry were assessed with submentovertex (SMV) radiographs, whereas condylar position within the glenoid fossa was analyzed with horizontally corrected tomograms. Relative to a mandibular coordinate system, the mandibular first molar on the crossbite side was found to be more lateral and relatively distal in comparison to the contralateral side. Skeletally, the mandible showed no asymmetry. Relative to the cranial floor, the mandible was “rotated” so that the condyle on the crossbite side was positioned relatively posteriorly in comparison to the contralateral side. A relative posterior positioning of the glenoid fossa was inferred, since there was no demonstrable mandibular skeletal asymmetry or condylar displacement within the fossa as shown on corrected tomograms in the crossbite group as compared with the Class I group. The results question whether it is appropriate to correct unilateral posterior crossbites in adults by orthodontic tooth movement alone, given the skeletal remodeling in the temporomandibular joint, which may have already occurred. (A M J O RTHOD D ENTOFAC O RTHOP 1995;107:394-400.)

Mandibular skeletal and dental asymmetry in Class II subdivision malocclusions

Mandibular symmetry was compared between a group of 28 subjects exhibiting Class II subdivision malocclusions and 30 subjects with Class I malocclusions who served as the control group. With submentovertex radiographs, symmetry was assessed by measuring the relative difference in spatial position of mandibular landmarks in both anteroposterior and transverse dimensions as determined by coordinate systems representing the cranial floor, mandible, and mandibular dentition. Only those variables representing the anteroposterior difference between right and left mandibular molar positions showed a statistically significant difference between the groups. Whether the position of the mandibular molars was measured relative to the cranial floor or within the mandible itself, the mandibular first molar was located more posteriorly on the Class II side of the subdivision malocclusion within a mandible that exhibited no other unusual asymmetry. (A M J O RTHOD D ENTOFAC O RTHOP 1994;105:489-95.)

Axial temporomandibular joint morphology: A correlative study of radiographic and gross anatomic findings

In degenerative diseases of the temporomandibular joint the mandibular condyle demonstrates changes in contour, including flattening and enlargement, resulting in an increased diameter of the articular surface. The purpose of this study was to determine if such alterations in the shape of the mandibular condyle can be visualized in submentovertex (axial) radiographs and correlated with pathologic changes of the temporomandibular joint. Submentovertex radiographs of 18 human cadaver specimens were made. The radiographic condylar dimensions, morphologic condylar outline, and angle of the condylar axis with respect to the transmeatal line were determined. The specimens were dissected and disarticulated, and radiographic findings were compared to anatomic structure. Osseous abnormalities were found in 21 of the 36 joints studied (58%). Perforations of the disk were found in nine of 31 joints (29%) investigated. No statistically significant differences between the normal condyles and condyles displaying osseous abnormalities were found in any of the radiographic parameters studied.

The submento-vertex projection in radiography of the temporomandibular joint.

Submento-vertex radiographs of the temporomandibular joints are often used to measure the horizontal condyle angulation. The present investigation shows that the radiographically determined angulation varies in a regular way with the angulation of the X-ray beam. The highest precision of measurement was obtained by employing metal indicators in ear-plugs placed in the external auditory canals instead of using skeletal reference lines. Some slight inter-examiner variation of the results were observed. However, this variation was considered to be acceptable in clinical work.