Japanesetooth positions and their relation to panoramic radiography L. R. Manson-Hing, D.M.D., M.S.,” T. M. Lund, D.D.S., M.S.+” a,nd T. OhbaN,D.D.S., D.M.XC.,~** Birmingham, AZa., Chicago, IZZ., ancl Kitakyushu City, Japan Although recent studies at the University of Alabama measured tooth positions in Negroid and Caucasoid patients, not many Mongoloid patients were available for study. The present study concerns tooth positions in Japanese patients and thus supplies the missing information on the Mongoloid group.
T
he focal troughs of the Panorex, Panelipse, and Orthopantomograph dental panoramic x-ray machines have been established with a uniform method.ls z The positions of the teeth in the dental arches of 240 Negro and Caucasian patients in Alabama have been plotted and the data related to the focal troughs of the above-mentioned x-ray machines.3 The patients were selected on the basis of race, sex, age, number of teeth, and occlusion. Occlusal registrations were made in fast-set acrylic. Tooth centers were identified and, with the midline-incisal point as a reference point, various composite drawings of tooth positions of patients were made. The total composite of all teeth revealed the striking similarity of the arches. Superimposition on the focal troughs showed that the focal trough of the Panorex easily encompassed all tooth positions. The focal trough of the Orthopantomograph encompassed all tooth positions, although tooth centers lie on the edges of the trough. The focal trough of the GE-3000 with profile index 7.5 encompasses all tooth positions, although some positions fall quite near the borders of the trough. Tooth positions were measured because there appears to be, at this time, no such entity as a standard dental arch form. The study recently conducted by two of us3 measured tooth positions in Negroid and Caucasoid patients. A *Professor Birmingham. “*Associate T-1
and Chairman, Professor
“*‘Associate Professor, Kitakyushu City, Japan.
of
Department Radiology, Department
of Dental Northwestern of
Dental
Radiology,
University
of Alabama
in
University
Dental
School,
Chicago,
Radiology,
Kyushu
Dental
College
797
large group of patients of the Mongoloid group were not available in Alabama. This study was designed to obtain tooth positions in Japanese patients in order to provide information regarding the Mongoloid group. METHOD As in the previous study,3 occlusal registrations were made on patients selected on the basis of sex, age, number of teeth, and occlusion. There was a total of twelve cells, with twenty patients in each cell. No attempt at randomization was made. Three age groups were chosen : (I) LLto 10 years, (2) 11 to 18 years, and (3) 19 years and over. Groups arranged according to the number of teeth present were: (1) exclusive of third molars, no more than six missing teeth; (2) no two adja,cent teeth missing; and (3) the patients had second deciduous molars or first permanent molars or second permanent molars if these should have been present. The occlusion was normal in that no obviously malaligned teeth were present; the occlusion was functional in that the patients were able to bite edge to edge in the incisor region as they are expected t,o do when being radiographed with a panoramic machine. Occlusal registrations were made in fast-set acrylic. The following points were identified and marked : (1) the center of the incisal edge of central and lateral incisors, (2) the center of the incisal edge or the cusp tip of cuspids, (3) the center of the central sulcus of premolars, and (4) the center of the occlusal surface of molars. 9 perpendicular bisector of the line segment connecting the two originally plotted molar points was extended through t,hc incisor area. This line, the perpendicular bisector, was taken as representing the sagittal plane of the patient and the midline of the arch. The plotting was then transferred to graph paper by tracing, using a. viewbox. The midpoint of the line connecting the two original points was placed on the Y axis of the graph, and the perpendicular bisector of the line was superimposed on the Y axis. The Y axis then extended through the points representing the teeth in the incisor area. A graph was constructed for each of the 120 patients. With the midline-incisal point serving as reference point, composite graphs of the twenty patients in each cell were made. A composite graph of all 120 patients was made, and a composite of the maxilla closed on the mandible in an edge-to-edge position of the incisors was made for all 120 patients. The focal troughs of the machines were compared with the occlusal registrations in edge-to-edge position of the incisors. The edge-to-edge tooth relationship is used to place the patient in the proper position as recommended by machine manufacturers. RESULTS Fig. 1 shows the plots of tooth positions. The maxillary tooth positions are shown above, and the mandibular tooth positions below. The six composite plots of the tooth positions of the twenty patients in each of the six cells used in the study were compared. When the plots of the arches are viewed with the midline-incisal point in the same position, little variation is observed between sexes. When the different age groups were considered separately, the plots of male and female were almost identical. Age appeared only to lengthen the arch apprecia-
Volume 41 Number 6
Japanese tooth positions
799
M
8%~. 1. Relative tooth poaitione of female maxillary teeth are shown above the mandibular
and male subjects teeth.
in three
age groups.
The
bly in the posterior area and widen the arch very slightly in the premolar area. The positions of the anterior teeth remained constant. A composite of the tooth positions of all 120 patients in the study is shown in Fig. 2 along with a composite of tooth positions of the maxilla closed on the tooth positions of the mandible, edge to edge in the anterior. The composites
Oral Burg. Jane, 19Tfi
Fig. 2. Composites of maxillary and mandibular tooth positions and a composite of maxillary and mandibular teeth closed upon each other with the anterior teeth edge to edge.
show that the area encompassed by the superimposition of maxillary and mandibular tooth positions does not differ appreciably from the area covered by the maxillary tooth positions alone or by the mandibular tooth positions alone. The area encompassed by the tooth positions of the Negroid plus Caueasoid group previously reported was traced, and a similar tracing was made of data on Japanese patients superimposed upon each other (Fig. 3). The new tooth positions fitted into the area of the earlier study but did not extend posteriorly as far as the earlier study. DISCUSSlOt
Occlusal registrations of patients showed no significant difference in tooth positions between the sexes. Only age had an effect; as the arches lengthened posteriorly, anterior tooth positions showed little variation. The information found in Jananese tooth positions was very similar to that seen in the Negroid and Caucasoid groups previously studied. Japanese tooth positions covered an area that fitted inside the area covered by the Negroid and Caucasoid groups. This is not surprising since the Japanese group is comprised of a more homogeneous set of individuals. The Negroid plus Caucasoid tooth positions definitely extended farther posteriorly; this is probably a reflection of the basic brachycephalic shape of Mongoloid heads. The data on Japanese patients were collected in the same manner as those
Volume Number
Japanese tooth positions
41 6
Caucasold
Pig. 3. Superimposition covered by tooth positions
+ Negro,d
.a.....
801
Japanese
of the aera covered by Japanese tooth of Negroid and Caucasoid subjects.
positions
upon the area
on the Negroid and Caucasoid patients. The marking of the occlusal registrations and plotting of tooth positions were done by the same person in both studies. This design permits comparisons to be made between the two sets of data. In addition, the relationship of Japanese tooth positions to the focal troughs of the Panorex, Panelipse, and Orthopantomograph can be reliably estimated. The relationships of Japanese tooth positions to the focal troughs of the Panorex, Panelipse, and Orthopantomograph are similar to the relationships established in a previous study3 for the Negroid and Caucasoid groups. This is to be expected, since the Japanese tooth positions fell within the ranges of the Caucasoid plus Negroid groups. However, the shortened anteroposterior dimension of the tooth positions of Mongoloid persons can affect the starting anteroposterior x-ray beam angle of panoramic x-ray machines. The Panorex machine developed in Japan has less of an anteroposterior x-ray beam direction when scanning the temporomandibular joint than does the Orthopantomograph which was developed in Finland. Developed with basically dolicocephalic people, the Orthopantomograph has the greater anteroposterior x-ray beam angle when scanning the temporomandibular joint and avoiding superimposition of the vertebral column at the same time. The Panelipse, developed in the United States for a less homogeneous group of people, exhibits an anteroposterior beam direction at the temporomandibular joint area that is between the Panorex and the Orthopantomograph. CONCLUSIONS 1. Tooth positions did not vary between ages and sexes in Japanese. 2. As the arches lengthened posteriorly, anterior tooth positions showed little variation. 3. Japanese tooth positions lie within the range shown for Caucasoid and Negroid persons. 4. Japanese tooth positions have a shorter anteroposterior dimension than their Caucasoid and Negroid counterparts. 5. The relationships of Japanese positions to the Panorex, Panelipse, and
Oral Burg. June, 1976
Orthopantomograph persons.
are similar
to those found
for Negroid
and C’aucasoid
REFERENCES
1. Lund, T. M., and Mason-Hing, L. R.: A Study of the Focal Troughs of Three Panoramic Dental X-ray Machines. Part I. The Area of Sharpness, ORAL SURG. 39: 318-328, 1975. 2. Lund, T. M., and Manson-Hing, L. R.: A Study of the Focal Troughs of Three Panoramic Dental X-ray Machines. Part II. Image Dimensions, ORAL SURG. 39: 647-653, 1975. Between Tooth Positions and Focal 3. Lund, T. M., and Manson-Hing, L. R.: Relations Troughs of Panoramic Machines, ORAL SURG. 40: 285-293, 1975. Reprint
requests
to:
Dr. L. R. Manson-Hing School of Den&try University of Alabama in Birmingham 1919 Seventh Ave., South Birmingham, Ala. 35294
NOTICE Readers may have noted that in recent issues of ORAL SURQERY, ORAL MFDICINE AND ORAL some sections have been omitted or have contained fewer pages than normal. This was the result of the unfortunate loss in the mail of a shipment of manuscripts between the Editor and the Publisher. The missing articles have now been replaced and all of them will be published in forthcoming issues.
PATHOLOGY
T
he focal troughs of the Panorex, Panelipse, and Orthopantomograph dental panoramic x-ray machines have been established with a uniform method.ls z The positions of the teeth in the dental arches of 240 Negro and Caucasian patients in Alabama have been plotted and the data related to the focal troughs of the above-mentioned x-ray machines.3 The patients were selected on the basis of race, sex, age, number of teeth, and occlusion. Occlusal registrations were made in fast-set acrylic. Tooth centers were identified and, with the midline-incisal point as a reference point, various composite drawings of tooth positions of patients were made. The total composite of all teeth revealed the striking similarity of the arches. Superimposition on the focal troughs showed that the focal trough of the Panorex easily encompassed all tooth positions. The focal trough of the Orthopantomograph encompassed all tooth positions, although tooth centers lie on the edges of the trough. The focal trough of the GE-3000 with profile index 7.5 encompasses all tooth positions, although some positions fall quite near the borders of the trough. Tooth positions were measured because there appears to be, at this time, no such entity as a standard dental arch form. The study recently conducted by two of us3 measured tooth positions in Negroid and Caucasoid patients. A *Professor Birmingham. “*Associate T-1
and Chairman, Professor
“*‘Associate Professor, Kitakyushu City, Japan.
of
Department Radiology, Department
of Dental Northwestern of
Dental
Radiology,
University
of Alabama
in
University
Dental
School,
Chicago,
Radiology,
Kyushu
Dental
College
797
large group of patients of the Mongoloid group were not available in Alabama. This study was designed to obtain tooth positions in Japanese patients in order to provide information regarding the Mongoloid group. METHOD As in the previous study,3 occlusal registrations were made on patients selected on the basis of sex, age, number of teeth, and occlusion. There was a total of twelve cells, with twenty patients in each cell. No attempt at randomization was made. Three age groups were chosen : (I) LLto 10 years, (2) 11 to 18 years, and (3) 19 years and over. Groups arranged according to the number of teeth present were: (1) exclusive of third molars, no more than six missing teeth; (2) no two adja,cent teeth missing; and (3) the patients had second deciduous molars or first permanent molars or second permanent molars if these should have been present. The occlusion was normal in that no obviously malaligned teeth were present; the occlusion was functional in that the patients were able to bite edge to edge in the incisor region as they are expected t,o do when being radiographed with a panoramic machine. Occlusal registrations were made in fast-set acrylic. The following points were identified and marked : (1) the center of the incisal edge of central and lateral incisors, (2) the center of the incisal edge or the cusp tip of cuspids, (3) the center of the central sulcus of premolars, and (4) the center of the occlusal surface of molars. 9 perpendicular bisector of the line segment connecting the two originally plotted molar points was extended through t,hc incisor area. This line, the perpendicular bisector, was taken as representing the sagittal plane of the patient and the midline of the arch. The plotting was then transferred to graph paper by tracing, using a. viewbox. The midpoint of the line connecting the two original points was placed on the Y axis of the graph, and the perpendicular bisector of the line was superimposed on the Y axis. The Y axis then extended through the points representing the teeth in the incisor area. A graph was constructed for each of the 120 patients. With the midline-incisal point serving as reference point, composite graphs of the twenty patients in each cell were made. A composite graph of all 120 patients was made, and a composite of the maxilla closed on the mandible in an edge-to-edge position of the incisors was made for all 120 patients. The focal troughs of the machines were compared with the occlusal registrations in edge-to-edge position of the incisors. The edge-to-edge tooth relationship is used to place the patient in the proper position as recommended by machine manufacturers. RESULTS Fig. 1 shows the plots of tooth positions. The maxillary tooth positions are shown above, and the mandibular tooth positions below. The six composite plots of the tooth positions of the twenty patients in each of the six cells used in the study were compared. When the plots of the arches are viewed with the midline-incisal point in the same position, little variation is observed between sexes. When the different age groups were considered separately, the plots of male and female were almost identical. Age appeared only to lengthen the arch apprecia-
Volume 41 Number 6
Japanese tooth positions
799
M
8%~. 1. Relative tooth poaitione of female maxillary teeth are shown above the mandibular
and male subjects teeth.
in three
age groups.
The
bly in the posterior area and widen the arch very slightly in the premolar area. The positions of the anterior teeth remained constant. A composite of the tooth positions of all 120 patients in the study is shown in Fig. 2 along with a composite of tooth positions of the maxilla closed on the tooth positions of the mandible, edge to edge in the anterior. The composites
Oral Burg. Jane, 19Tfi
Fig. 2. Composites of maxillary and mandibular tooth positions and a composite of maxillary and mandibular teeth closed upon each other with the anterior teeth edge to edge.
show that the area encompassed by the superimposition of maxillary and mandibular tooth positions does not differ appreciably from the area covered by the maxillary tooth positions alone or by the mandibular tooth positions alone. The area encompassed by the tooth positions of the Negroid plus Caueasoid group previously reported was traced, and a similar tracing was made of data on Japanese patients superimposed upon each other (Fig. 3). The new tooth positions fitted into the area of the earlier study but did not extend posteriorly as far as the earlier study. DISCUSSlOt
Occlusal registrations of patients showed no significant difference in tooth positions between the sexes. Only age had an effect; as the arches lengthened posteriorly, anterior tooth positions showed little variation. The information found in Jananese tooth positions was very similar to that seen in the Negroid and Caucasoid groups previously studied. Japanese tooth positions covered an area that fitted inside the area covered by the Negroid and Caucasoid groups. This is not surprising since the Japanese group is comprised of a more homogeneous set of individuals. The Negroid plus Caucasoid tooth positions definitely extended farther posteriorly; this is probably a reflection of the basic brachycephalic shape of Mongoloid heads. The data on Japanese patients were collected in the same manner as those
Volume Number
Japanese tooth positions
41 6
Caucasold
Pig. 3. Superimposition covered by tooth positions
+ Negro,d
.a.....
801
Japanese
of the aera covered by Japanese tooth of Negroid and Caucasoid subjects.
positions
upon the area
on the Negroid and Caucasoid patients. The marking of the occlusal registrations and plotting of tooth positions were done by the same person in both studies. This design permits comparisons to be made between the two sets of data. In addition, the relationship of Japanese tooth positions to the focal troughs of the Panorex, Panelipse, and Orthopantomograph can be reliably estimated. The relationships of Japanese tooth positions to the focal troughs of the Panorex, Panelipse, and Orthopantomograph are similar to the relationships established in a previous study3 for the Negroid and Caucasoid groups. This is to be expected, since the Japanese tooth positions fell within the ranges of the Caucasoid plus Negroid groups. However, the shortened anteroposterior dimension of the tooth positions of Mongoloid persons can affect the starting anteroposterior x-ray beam angle of panoramic x-ray machines. The Panorex machine developed in Japan has less of an anteroposterior x-ray beam direction when scanning the temporomandibular joint than does the Orthopantomograph which was developed in Finland. Developed with basically dolicocephalic people, the Orthopantomograph has the greater anteroposterior x-ray beam angle when scanning the temporomandibular joint and avoiding superimposition of the vertebral column at the same time. The Panelipse, developed in the United States for a less homogeneous group of people, exhibits an anteroposterior beam direction at the temporomandibular joint area that is between the Panorex and the Orthopantomograph. CONCLUSIONS 1. Tooth positions did not vary between ages and sexes in Japanese. 2. As the arches lengthened posteriorly, anterior tooth positions showed little variation. 3. Japanese tooth positions lie within the range shown for Caucasoid and Negroid persons. 4. Japanese tooth positions have a shorter anteroposterior dimension than their Caucasoid and Negroid counterparts. 5. The relationships of Japanese positions to the Panorex, Panelipse, and
Oral Burg. June, 1976
Orthopantomograph persons.
are similar
to those found
for Negroid
and C’aucasoid
REFERENCES
1. Lund, T. M., and Mason-Hing, L. R.: A Study of the Focal Troughs of Three Panoramic Dental X-ray Machines. Part I. The Area of Sharpness, ORAL SURG. 39: 318-328, 1975. 2. Lund, T. M., and Manson-Hing, L. R.: A Study of the Focal Troughs of Three Panoramic Dental X-ray Machines. Part II. Image Dimensions, ORAL SURG. 39: 647-653, 1975. Between Tooth Positions and Focal 3. Lund, T. M., and Manson-Hing, L. R.: Relations Troughs of Panoramic Machines, ORAL SURG. 40: 285-293, 1975. Reprint
requests
to:
Dr. L. R. Manson-Hing School of Den&try University of Alabama in Birmingham 1919 Seventh Ave., South Birmingham, Ala. 35294
NOTICE Readers may have noted that in recent issues of ORAL SURQERY, ORAL MFDICINE AND ORAL some sections have been omitted or have contained fewer pages than normal. This was the result of the unfortunate loss in the mail of a shipment of manuscripts between the Editor and the Publisher. The missing articles have now been replaced and all of them will be published in forthcoming issues.
PATHOLOGY
