FH Plane Research Articles

Evaluation of pharyngeal airway space amongst different skeletal patterns

The aim of the present study was to evaluate the dimensions of the pharyngeal airway space (PAS) in awake, upright children with different anteroposterior skeletal patterns using cone beam computed tomography (CBCT). The volume, area, minimum axial area and seven linear measurements of PAS were obtained from the CBCT images of 50 children (mean age 9.16 years). The patients were divided in two groups according to the ANB angle (group I 2°≤ANB≤5°; group II ANB>5°). Means and standard deviations of each variable were compared and correlated using independent t-test and Pearson's correlation test. There were statistically significant differences in the following parameters: angle formed by the intersection between NA and NB lines (p<0.001), angle formed by the intersection between SN and NB lines (p<0.05), Minimal pharyngeal airway space between the uvula and the posterior pharyngeal wall (p<0.05), airway volume (p<0.01), airway area (p<0.01) and minimum axial area (p<0.05). The anteroposterior cephalometric variable SNB had positive correlation with the variables PAS-UP (p<0.01), Minimal pharyngeal airway space between the uvula tip and the posterior pharyngeal wall (p<0.05), Pharyngeal airway space on mandibular line (p<0.05), Minimal pharyngeal airway space between the back of the tongue and the posterior pharyngeal wall (p<0.05), volume airway (p<0.05), airway area (p<0.05) and minimum axial area (p<0.05). The vertical cephalometric variables angle formed by the intersection between SN and GoGn lines (p<0.05) and angle formed by the intersection between FH and mandible plane (p<0.05) showed negative correlation with PAS-UT. These results showed that PAS was statistically larger in group I than group II, indicating that the dimensions of the PAS are affected by different anteroposterior skeletal patterns.

Comparison of Normal Permanent and Primary Dentition Sagittal Tooth-Crown Inclinations of Japanese Females

The purpose of this study was to clarify the characteristics of permanent and primary toothcrown inclinations. Landmark points from cephalograms and dental casts of two groups; 23 women (mean 20.3±3.3 years) and 11 girls (mean 5.2±0.1 years) were digitized, and the coordinates were integrated and transformed to a standardized plane. The 3-dimensional crown inclinations were projected on the sagittal plane, and the angles between the tooth vectors and the FH plane were calculated. An independent-group t-test was used to test for group differences of each tooth inclination, and correlation coefficients were generated for the inclination angles among the permanent and primary teeth. Most maxillary tooth-crown inclinations showed significant age-related differences, while only the second premolar and primary second molar differed significantly in the mandible. The maxillary molars were parallel to the corresponding mandibular molars and correlated with each other, but the primary molars were not. Significant correlations were found between inclinations of most permanent teeth, but not the primary teeth. Maxillary tooth-crown inclinations change during growth, but tooth-crown inclinations of the mandibular teeth do not.

Craniofacial growth changes and dental attrition in the primary dentition

Presence of pronounced incisal and occlusal wear in primary dentition is fairly common in children. Several factors are implied, however, the possible correlation of craniofacial growth to the occurrence of severe incisal tooth wear in children has not been described to date. Thus, this study was aimed to find any association between the craniofacial growth changes and the occurrence of severe incisal wear in children. Twenty-seven sets of series of dental casts and corresponding lateral cephalograms are selected from the archive of Pediatric Dentistry, Department of Tokyo Medical and Dental University Hospital. Samples were divided into two groups based on the extent of incisal wear observed on the primary maxillary anterior teeth: slight attrition (N = 13) and severe attrition (n = 14) groups. Lateral cephalograms at early deciduous dentition at T1 (3.5 ± 0.6 years old) and late deciduous dentition at T2 (6.2 ± 0.6 years old) were manually traced and 17 linear and 22 angular measurements were measured with analyzing software (WinCeph ver.9). Annual growth rate for each sample was calculated to determine any significant difference between samples from two groups. Significant horizontal growth of the mandible with both the reduction of anterior tooth height and increase of posterior tooth height were found in the severe attrition group. Reduction of upper incisor angle to FH plane and upper dental arch length were also related with the attrition of teeth. The incisal tooth wear of deciduous teeth was significantly associated with the craniofacial growth changes.

Three-dimensional analysis of pharyngeal airway form in children with anteroposterior facial patterns

To test the null hypothesis that the form and size of the pharyngeal airways in preadolescents do not differ among various skeletal patterns. Sixty healthy children (mean age, 11.79 ± 1.11 years) were divided into three groups by anteroposterior jaw relationships. Using cone-beam computed tomography, the inclination and the volume of the pharyngeal airway were measured and compared with craniocervical angles and cephalometric variables. Children with Class II malocclusion have a larger angle between the FH plane and midplane of the oropharyngeal airway (ang-OA) compared with children with Class I and III malocclusion (P < .01). Ang-OA was significantly correlated with craniocervical angle (ang-cc) and anteroposterior variables, mainly ANB angle, Pog-N perpendicular (P < .01). Airway volume had a positive correlation with facial depth (P < .01). Children with Class II malocclusion have more backward orientation and smaller volume of the pharyngeal airway than do children with Class I and III malocclusion. Inclination of the oropharyngeal airway might be a key factor in determining the form of the entire pharyngeal airway and is related to head posture.

How to revise and utilise the cephalogram for craniofacial dysostosis—Modification of the porion and the McNamara line

McNamara line analysis is often utilised in orthognathic surgery and is particularly useful in that it can easily express the extent of maxillo-mandibular deformity quantitatively. However, in craniofacial dysostosis (CFD), the location of the porion (PR) is sometimes displaced inferiorly. The McNamara line depends on the Frankfurt horizontal plane (FH plane), and hence, its deviation is often extremely distorted in CFD. The objective of this study was to enable more correct reflection of deformities of CFD patients on lateral cephalogram analysis. The lateral cephalograms of 152 Asian individuals were involved. angle basion(BA).orbitale(Or).PR, angle BA. nasion(NA).PR, and the distance from BA to PR on the BA-NA plane were measured and each standard range was established. Using these ranges, modified PR (mPR) is supposed to lie within a fairly small area. Second, we utilised mPR in the practice of McNamara line analysis in CFD patients. In both cases in the present study, it was confirmed that modified McNamara line analysis can express the deformities more precisely than conventinal analysis, as far as the maxillo-mandibular relationship is concerned. However, particularly in Case 2, both the cranio-maxillary and cranio-mandibular relationships were not entirely consistent with the lateral profile appearance even on modified McNamara line analysis.

Evaluation of 2 Different Reference Planes Used for the Study of Asymmetric Facial Malformations

The purpose of this study was to evaluate if Frankfort plane (FH) and plane passing through the lateral semicircular canals (LS) can be used as reference planes in three-dimensional analysis.Ten patients with facial asymmetry underwent a three-dimensional computed tomography. Computed tomographic images were processed by means of a commercial software and a personal computer to obtain a three-dimensional virtual craniofacial model. The average Frankfort plane and the plane passing through the LS were identified. The distance from the above-mentioned planes to the first upper molar and upper canine cusp was measured.It was not possible to detect an FH plane in any of the patients. Right FH, left FH, average FH, and LS plane were traced. The discrepancies among reference planes were significant in cases with severe asymmetry. A minimal discrepancy was noticed in patients with light asymmetry.In patients with severe asymmetry, the LS plane results in steady, reproducible, detectable, and closer to the patient's anatomy, representing a valid reference plane for three-dimensional computed tomography analysis.

Comparison of landmark position between conventional cephalometric radiography and CT scans projected to midsagittal plane

Objective: The purpose of this study is to compare landmark position between cephalometric radiography and midsagittal plane projected images from 3 dimensional (3D) CT. Methods: Cephalometric radiographs and CT scans were taken from 20 patients for treatment of mandibular prognathism. After selection of landmarks, CT images were projected to the midsagittal plane and magnified to 110% according to the magnifying power of radiographs. These 2 images were superimposed with frontal and occipital bone. Common coordinate system was established on the base of FH plane. The coordinate value of each landmark was compared by paired t test and mean and standard deviation of difference was calculated. Results: The difference was from −0.14 ± 0.65 to −2.12 ± 2.89 mm in X axis, from 0.34 ± 0.78 to −2.36 ± 2.55 mm (6.79 ± 3.04 mm) in Y axis. There was no significant difference only 9 in X axis, and 7 in Y axis out of 20 landmarks. This might be caused by error from the difference of head positioning, by masking the subtle end structures, identification error from the superimposition and error from the different definition. Conclusions: This study revealed innate shortcomings of radiography. For the development of 3D ceph

Ａｐｅｒｔ症候群に対する骨延長術後における延長方向および延長量の検討

We conducted maxillary distraction utilizing internal distraction devices in three patients with Apert syndrome. For these cases, we examined maxillary bone displacement, the relapse of bone distraction length and inclination changes. For this study, we chose three female patients between nine years two months and fifteen years eight months of age at the time of operation. After receiving a Le Fort III osteotomy, each patient received maxillary advancement utilizing internal distraction devices. The device was activated 1.0mm per day. After the lengthening devices were removed, the maxilla was reconstructed using poly L-lactic acid (PLLA) plates. Corresponding to pre-operation, post-operation, 1-year and 2-year post-operative periods, lateral cephalogram tracings were made. By standardizing the superimposition lateral cephalogram for the cranial base, each measurement point reflected it on the FH plane. Based on these observations, we studied the displacement in the horizontal and vertical directions of the maxilla which were indicated by point A, and we examined the inclination changes of the palatal plane based on the FH plane. As a result, the distraction lengths at point A were from 10.0mm to 14.8mm. In the two younger age groups, large differences between setting and real quantities of bone distraction lengths have not been found. Yet for the other case, actual distraction length was less than the setting length. As for the bone distraction length relapse, an average rate of 4.0% was recognized in the horizontal direction, but was not found in the vertical direction. To explain such a small relapse rate, the following reasons were discussed: longer than three months of retention period had been taken for the studies; mini-plate fixation had been applied as well as retention with the maxillary protractor; and anterior and downward growth of maxilla had taken place. The changes of the palatal plane angle had rotated counter-clockwise from 1.5° to 3.0° in the pre- and post-operative stages, and had rotated clockwise from 0.5° to 3.0° in the immediately-post and 1-year post-operative period. For the 1-year and 2-year post-operative period, a clockwise rotation rate from 1.0° to 1.5° was recognized. The palatal plane had rotated counter-clockwise after the operation, but we succeeded in achieving a relapse rate almost the same as the preoperative length.

下顎位を改善し顔貌を回復した総義歯１症例

This is a clinical case report of esthetic and masticatory impairment due to a mandibular protrusion during occlusion. The patient was a complete edentulous subject who complained about esthetic and matiscatory disturbance. First of all, treatment dentures were done, in order to improve the mandible position and recover the facial aspect. Objective evaluations were carried out to compare the improvements achieved after the insertion of the new dentures. The treatment dentures were used to improve patient's mandible position as well as vertical dimension. Once the facial appearance was recovered as a result of an appropriate mandible position, a reduction of the angle formed between the FH plane and the A-B plane from 87 to 83 was recognized after the insertion of the new dentures through the analysis of lateral cephalograms. It indicates that the mandible's position changed to backward position resulting in an improvement of the facial aspect. In the present clinical case report, not only subjective evaluation for appropriate mandible position and vertical dimension, but also including objective evaluation methods allowed us to evaluate and compare objectively the patient's pre and post operative condition.

Outer shape changes of human masseter with contraction by ultrasound morphometry

The multipennate masseter has a complex internal architecture, which suggests the contraction is not uniform within the muscle. The heterogeneous contraction may cause inequable changes of the muscle's outer shape. This study aimed to elucidate the outer shape changes of the whole masseter with clenching by multipoint measurement of serial ultrasound images. Serial coronal images (perpendicular to the FH plane, 3 mm interval) of the right masseter of five healthy men were obtained with a real-time ultrasonograph equipped with a 13 MHz linear-array transducer. To define the relationship between the transducer and cranium, we used a 3D mechanical stage with a face-bow. Registrations were made during muscle relaxation and maximal clenching. The distance between the lateral and medial outlines of the muscle was measured at intervals of 1mm from the origin to insertion in each image as the thickness at the corresponding measured point. The thickness of the relaxed and contracted muscle (R and C) and its difference (Delta) varied among the measured points. Muscle thickness at most measured sites increased with clenching, whereas it decreased at several sites, mainly near the origin and insertion. There were positive correlations in every subject both between R and C, and between C and Delta. On the other hand, the correlation between R and Delta were negative or weak. Changes of thickness with clenching showed great disparity within the masseter, which may result from the complexity of the contraction properties due to the multipennate structure and functional heterogeneity.

上下顎移動術による中顔面軟組織の三次元表面形状変化―非接触型レーザー三次元形状計測装置を用いて

In severe skeletal mandibular prognathism with soft tissue distortion, maxillary advancement, combined with mandibular set-back operation, is frequently performed to improve facial esthetics. However, few studies have been reported on the three-dimensional soft tissue changes following two-jaw surgery in Japanese subjects. Therefore, we used a threedimensional non-contact laser scanner (VIVID700®MINOLTA) to assess presurgical and postsurgical soft tissue changes, focused on the midface. Subjects constituted five female prognathtic patients without facial asymmetry, who had received sagittal split ramus and Le Fort I osteotomies at Niigata University Dental Hospital. All cases received their preoperative and postoperative orthodontic treatment by the standard edgewise system. To standardize the scanning procedure, the VIVID700 was fixed by a special metal frame, ear rods were used to stabilize the head, and the FH plane was kept horizontal. The scanner allowed a single scan in 0.6 seconds. Presurgical and postsurgical images were taken and processed; 16 horizontal and 17 sagittal lines were constructed and were used to produce an average face for each stage. Average form showed little change in the upper region of the cheek, while the lower region of the cheek became full. In the nose area, the nose tip moved anterior and coronal, and the nasal breadth tended to widen. The upper lip moved anterior, on average.In conclusion, although the main aim of maxillary advancement is to improve midfacial fullness, the concomitant nasal changes should be considered, and its effect on treatment outcome be ascertained.

The postglenoid tubercle: prevalence and growth

To quantify the prevalence and growth of the postglenoid tubercle in a skull sample and in children. a) ninety skulls ranging in age from between 2 years and adulthood, b) sixtyfour corrected lateral tomograms of left and right temporomandibular joints of 32 boys and girls. Their age range was between 9 and 11 years. Impressions of the temporal fossae of the skull material were taken with a silicone type impression material, using a face-bow for leveling the base of the impression parallel to the FH plane. Each impression was divided into two halves along a paramedian plane from the tip of the postglenoid tubercle through the middle of the articular eminence and the surface was photocopied to a 200% scale. Height was measured with an electronic caliper. The presence or absence of a postglenoid tubercle was established on the corrected tomograms. Seventy-nine percent of the skulls had a postglenoid tubercle. It steadily enlarged and reached almost its final dimension by the age of 13 years. On corrected tomograms, 66% of the children showed a postglenoid tubercle. a) the postglenoid tubercle exists in a high percentage of human temporomandibular joints b) growth is almost completed by the age of 13, and c) there exists a right-left symmetry.

Assessment of the relationships among posture, maxillomandibular denture complex, and soft-tissue profile of aesthetic adult Korean women.

The objective of this study was to assess the relationships among the posture, the maxillomandibular denture complex, and the soft-tissue profile of aesthetic adult Korean women. From an initial group of 346 women, the authors examined 28 beautiful adult Korean women who had normal vertical and sagittal skeletal relationships and normal occlusion. There were no differences in the inclinations of the incisors to the occlusal planes in the maxilla and the mandible in the data for Korean women vs. Arnett's data for white women. However, the overbite and overjet in Korean women were slightly smaller than in white women. AB to maxillary occlusal plane angle (MxOP) represented the anteroposterior denture base discrepancy to the occlusal plane. Angulation of the maxillary occlusal plane to the Frankfurt (FH) plane and the true vertical line at submasale (TVL) (Sn) was a little steeper in Korean women than in white women. The FH plane was almost parallel to the true horizontal line in Korean women who had normal vertical and sagittal skeletal relationships and normal occlusion. With regard to soft-tissue variables, the upper lip length (Sn-Stms), interlabial gap, upper incisor exposure, nasolabial angle, lip and nose tip projection value, and TVL (Sn)-to-upper lip line (UL) angle showed interracial differences. The results of this study can assist in the diagnosis and treatment planning of orthognathic surgery.

Dangerous angles and depths for middle ear and middle cranial fossa injury during arthroscopy of the temporomandibular joint

Purpose: Several reports have suggested a risk of injury to the middle cranial fossa and middle ear during arthroscopic procedures in the superior joint space of the temporomandibular joint (TMJ). However, there has been no anatomic study of directions and distances of the TMJ from the posterior portal in relation to the risk of mandibular fossa injury. In this study, the angles and depths at which the risk is greatest for injury to the deepest point of the mandibular fossa (DP) and to the middle ear during arthroscopy were analyzed. Materials and Methods: Three-dimensional measurements of 96 mandibular fossae in 48 dry skulls were made. Results: It was found that the distance from the lateral rim of the fossa to DP and Hugier's canal was 9.50 ± 2.07 mm and 17.04 ± 3.09 mm, respectively. The most dangerous angle for DP injury in the Frankfort horizontal plane (FH plane) was an inclination of the instrument base of −8° dorsad and 17 and 19° caudad in the frontal plane. The most dangerous angle for Hugier's canal injury was a tilting of the instrument base of 15° ventrad in the FH plane and −2° craniad in the frontal plane. However, these values showed a wide range. Conclusion: It was concluded that great care must be exercised in manipulation of instruments near the DP and Hugier's canal to avoid injury to the middle ear or penetration into the middle cranial fossa.

頚椎の配列形態と顎顔面形態の関連性について

The purpose of this study was to investigate the correlation between cervical vertebra alignment and factors of occlusion, dentofacial morphology, and head posture. The authors analyzed the relationship of cervical inclination and curve and dentofacial morphology using cephalometric photography. Subjects consisted of one hundred normal young adults without TMJ symptoms (an average age of 26 years old).The following results were obtained:1. The inclination of the dens showed a positive correlation to FH plane, palatal plane, occlusal plane and mandibular plane. In the case of forward flexion of dens, each inclination was high. But for backward flexion, each inclination was low.2. The curve from the second cervical vertebra to the fourth cervical vertebra showed a positive correlation to the inclination of the dens. In case of forward flexion of dens, the curve was small. But for backward flexion, the curve was large. And it did not correlate to each plane. It was shown that inclination of the dens correlated with dentofacial morphology and the curve of vertebra.

若年発症顎関節症の歯科学的研究 上顎臼歯部冠軸に関する検討

The subjects were 39 female patients with juvenile TMJ arthrosis (T group) and 30 healthy females (N group) who visited the Dept. of Oral Surgery in the Dental Clinics of Nagoya University Hospital, Dept. of Oral Surgery in the Dental Clinics of Fujita-Gakuen Health University Hospital and the Clinics of the Lion Foundation for Dental Health during a period of 3 years and one month from April 1983 to April 1986. The following evaluations were made: 1) U 5 to occlusal plane angle, 2) U 6 to occlusal plane angle, 3) U 7 to occlusal plane angle, 4) U 5 to U 6 angele, 5) U 7 to U 6 angle, 6) U 5 to FH plane angle, 7) U 6 to FH plane angle, 8) U 7 to FH plane angle, and 9) FH plane to occlusal plane angle. The following results were obtained: 1. U 7 to occlusal plane angle in the T group (82.0±6.5) was significantly smaller than that in the N group (85.7±8.2). 2. U 7 to FH plane angle in the T group (113.0±6.8) was significantly larger than that in the N group (108. 4±8.5). 3. Significant differences between the T group (15. 2±4.2) and the N group (15.0±4.0) were not seen in terms of the FH plane to occlusal plane angle. 4. In conclusion, a majority of the T group patients showed a centrifugal inclination of the upper second molar.

良好な咬合保持者の顎・顔面形態に関する研究

Usually, diagnosis and treatment plans are made on the basis of data obtained from subjects with normal occlusion in orthodontic treatment. Morphologically, there are three types of faces for subjects with normal occlusion : convex, straight, and concave. It is therefore necessary to adjust treatment goals in accordance with the facial type to maintain stable and consistant treatment results. However, taking measures by the facial type has not yet been sufficiently pursued. Therefore, relations between antero-posterior relationships of the upper and lower jaws and tooth position were studied with regard to subjects with good occlusion. Of 1, 047 male students whose gnathostatic models, oriented facial photograms, and roentogenocephalograms were completed and in custody of the Department of Orthodontics, Kyushu Dental College, 178 subjects who had Angle class I relationships and good occlusion, both overjet and overbite, over 0.5mm and under 4.5mm were selected for the study. With use of their lateral roentogenocephalograms, linear and angular measurements were taken on 35 items and examinations including multiple regression analysis were made. The results were as follows : 1. Convexity[mm]of the materials used for this study was -7.0 to 10.0mm (1.7±3.0mm), A-B was -18.3 to 3.5mm (-5.8±4.2mm) and ∠ANB was -5.1 to 8.6°(1.9±2.4°). Within these ranges, maintenance of fairly good overjet and overbite was considered possible even with antero-posterior skeletal discrepancy of the upper and lower jaws. 2. Correlation coefficients of convexity[mm]with A-B and with ∠ANB were -0.82 and 0.96, respectively, showing strong correlation. The greater the convexity[mm]was, the greater the antero-posterior difference of the upper and lower jaws was skeletally. With smaller convexity[mm], antero-posterior difference of the upper and lower jaws was smaller. 3. Correlation coefficients of convexity[mm]with ∠FH-1 and with ∠FH-1 were -0.43 and -0.72, respectively. With greater convexity[mm], the upper central incisor tended to show lingual tipping and the lower central incisor labial tipping. With smaller convexity[mm], the trend for both incisors was reversed. 4. In multiple regression analysis, the linear measurement items N-A, N-B, and A-B with FH plane as the base were expressed by a contribution of 0.96 and over derived by angular measurements of ∠SN-FH, ∠SNA, ∠SNB, and ∠ANB with SN plane as the base. Each of FH plane and SN plane has advantages as the plane for measuring. Therefore, in making evaluation of antero-posterior relationships of the upper and lower jaws, linear measurements with use of FH plane and angular measurements with use of SN plane should be taken into consideration.

下顎前突症に対する顎矯正手術後の軟組繊側貌の予測に関する研究

In order to make predictions for softtissue profile of lower face after orthognathic surgery for mandibular prognathism, lateral radiographic cephalograms of 23 subjects of skeletal class III malocclusion who were given mandibular body ostectomy were used and the following study was made. 1. The subjects for this study consisted of 23 females with an average age of 18 years and 9 months. All subjects had skeletal Class III malocclusion and 11 of these had a complication of open bite. Twenty subjects were given step ostectomy of the mandibular body and the other three vertical ostectomy. Right lateral radiographic cephalometric films were taken as reference at five points in time : before, immediately after, 3 months after, 6 months after, and a year after operation. 2. For cephalometric measurement, coordinates with the straight line originating from S and parallel to FH plane as X axis and the line at right angle to it as Y axis were prepared and 13 landmarks of hardand softtissue were measured on a digitizer. 3. Changes with time in hard and soft tissue profile were plotted on the coordinates as changes of the landmarks and their average movements were examined and the following results were obtained. 1) Marked posterosuperior displacement of the mandible as a result of operation was seen as a change in the hard tissue profile. Until 3 months after operation, superoanterior displacement of the mandible along with occlusal reconstruction was observed. Thereafter, until 6 months after operation, a trend for relapse consiting mainly of anterior displacement continued. However, after 6 months, no significant changes were seen and changes were about stabilized. 2) During the period before and 3 months after operation, Ls and Sto were displaced posteroinferiorly and 6 points below Li posterosuperiorly reflecting the displacement of the hard tissue. During the period 3 to 6 months after operation, slighte displacement anteroinferiorly 6 points below Li was seen. However, after 6 months no significant changes were seen and the changes were about stabilized. 4. With a view to making predictions for soft tissue profile after orthognathic surgery for mandibular prognathism, multiple regression analysis was made of hard and soft tissue landmarks before and over 6 months after operation, five items of thickness of soft tissue before operation, and overjet and overbite before operation, as variables. For selection of independent variables, stepwise selection at F level 2.0 to enter or remove variables was chosen. As a result, the linear multiple regression equation as shown in Table 12 was obtained, and factors of change for each soft tissue landmark after operation were analyzed. Then, a multiple regression equation which shows a multiple correlation coefficient of over 0.95 with as little variables as possible and is statistically significant at 0.01 by F-test was determined as the predicting equation. Furthermore, in order to visually examine accuracy of the predicted soft tissue profile, a computer program which allows simultaneous graphic presentation of pre- and post-operative hard and soft tissue profiles obtained from the actual values and the predicted profiles was prepared. With use of this program, the predictinig equation was applied to the 23 cases used to derive the regression equations and to the 3 additional cases which were not included in the original material as an external check, and visual comparison with the postoperative profiles obtained from the actual values was made. This comparsion showed fair accuracy in all these samples and indicated its general applicability in clinical use.

外頬部に於ける顆頭の位置決定の X 線学的研究

The apparatus for the cranioplanigraphy used in this study was first checked for its rate of magnification as well as for its extent of precision to ensure best result, and based on these knowledges, measurements were undertaken to determine the exact position of the condyle head on the sagittal plane, as well as its relative position against the glenoid fossa and glenoid tubercule, taking FH plane and nasoauricular line a standard line and porion and the center of external auditory meatus as origin point. The study also included the slanting angle of condyle path on sagittal plane made against nasoauricular line. The results were summarized as follows. 1. The condyle head as measured in male jaws under the central occlusion was located 11.12 mm far from porion and 1.85 mm directly beneath FH plan and 3.15 mm far from the bottom of glenoid fossa with regard to the right jaw, while it was located 10.82 mm far from porion and 2.22 mm beneath FH plane and 3.18 mm far from the bottom of glenoid fossa with regard to the left jaw. Measured on nasoauricular line, the condyle was located 9.50 mm far from the center of external auditory meatus and 11.18 mm directly above nasoauricular line and further, 14.6 mm far from the center of external auditory meatus at the elevated angle of 50 degrees with nasoauricular line as base line. In the female head, the condyle head on the right jaw occupied the point 11.29 mm far from the porion along FH plane and 1.6 mm beneath the plane and 3.2 mm far from the bottom of glenoid fossa. In the left jaw, it occupied the point 11.27 mm far from porion along FH plane and 1.32 mm beneath the plane and 2.94 mm distant from the bottom of glenoid fossa. Further, it was situated 7.78 mm far from the center of external auditory meatus along nasoauricular line and 11.44 mm vertically above that line and 13.8 mm far from the center of external auditory meatus at the elevated angle of 56 degrees with nasoauricular line as base line. 2. The distance between glenoid fossa and the condyle head in the male was respectively 3.15 mm (right side) and 3.18mm (left side) and in the female 3.2mm (right side) and 2.94 mm (left side). 3. The distance between the bottom of glenoid fossa and the top of glenoid tubercle was 7.32 mm (right jaw) and 7.82 mm (left jaw) in the male subject and 7.17 mm (right) and 7.14 mm (left) in the female. 4. The slanting angle of the condyle path in sagittal plane against nasoauricular line was 33.64 in the male and 32.68 in the female. 5. It was concluded that the values designating the position of the condyle as obtained by taking the external auditory meatus center as point of origin and the nasoauricular line as base line proved useful in the clinic of prosthtic dentistry.

顔面規格写真(側面), 頭部 X 線規格写真(側面), および顎態模型上の計測による数値の比較

Three laboratory methods are available for the diagnosis and assessment of dental and dentofacial changes that have occcurred due to physiological growth of asubject on one hand and to the effects of any orthodontic treatment given him on the other hand. These are the facial photogrammetry, cephalometric radiography and oriented plaster models of upper and lower jaws. Although each of these methods has its own merit in the study of dental and dentofacial changes, there has hardly been any attempt to correlate sets of data obtained by these methods and bring them into a more integrated system which would possibly furnish more convenient and reliable criteria in diagnosing the orthodontic patients. As an approach to get some informations about such correlation among the three methods, three sets of measurements were respectively made on a total of 149 subjects aged 6 to 20, consisting of 71 males and 78 females, all having nomal occlusion and being the residents of Kitakyushu. FH planes as obtained in the respective method were taken as principal reference in all measurement. The relative distances or depths of points on the FH plane that were obtained by projection from the selected landmarks in the soft and hard tissues of the face were compared and assessed among the three methods. For the purpose of gaining a general trend of age change in the soft and hard tissues of the face, a series of profilograms were constituted for 5 age stages groups covering 6 to 20 years of age for both sexes, utilizing the facial photogrammetry and cephalometric radiographic data. In making the pictures, FH plane was taken as X axis and a vertical line passing porion as origin was taken as Y axis. Followiug conclusions were drawn from the above studies. 1) Of the dental and dentofacial growth as revealed by the three methods, it was particularly noted that the increments measured by the facial photogrammtry proved least as compared to those measured by the remaining methods. This represented that the growth increment in the soft tissues was exceeded by that in the hard tissues. 2) For the determination of upper jaw positions of cephalometric radiography and plaster model on oriented photogrammetry, centrale and subnasale are so far adopted conveniently as reference points. For the determination of lower jaw position, there is sulcus mentolabialis available as reference point. Of these, centrale was found in the present study to be more accurate point of reference in determining the upper jaw position on facial photogrammetry, because the former could be placed more close to the forward limit of upper jaw than the latter. However, in determining the anteroposterior relation of both jaws on facial photogrammetry, subnasale was found to serve as more accurate point of reference in upper jaw, because the growth change of soft tissue thickness at the site of sulcus mentolabialis closely resembled that at the site of subnasale. 3) Comparison of data as obtained from measurement by both cephalometric rabiography and plaster model revealed that the forward inclination of central incisors was accompanied by the increment of distances between the basal bone and gum and between gum and tooth root apices in both upper and lower jaws of subjects except for those in the stage of deciduous dentition. 4) In subjects older than those having deciduous dentition, the increment by growth of upper jaw as measured by cephalometric radiography was approximately equal to the increment as measured by oriented plaster model.