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A method for determining anterior mandibular height using a radiographic paralleling measuring system
J Oral Maxillofac
Surg
44388-192.1986
A Method for Determining Anterior Mandibular Height Using a Radiographic Paralleling Measuring System GEORGE J. HADEED, DMD,* DONALD J. PIPKO, DMD, MSD,t AND THOMAS G. ZULLO, PhD* A parallel radiographic technique that allows calculation of mandibular height at the midline with a mean error of 0.3 mm is presented. This accuracy gives clinical confidence in the placement of endosseous implants.
angle technique, made radiographic measurements on cadavers with periapical films. Accuracy was greatest in the mandibular posterior area, followed by the maxillary anterior, mandibular anterior, and. finally, the maxillary posterior regions. The largest error was I .6 mm; fewer than 10% of the measurements had an error greater than 1.0 mm. Bjiirn and Holmberg6 analyzed bone height scores and found the intraoral technique more accurate than the orthopantomographic images. However, they cited the latter as a valuable tool for the investigation of alveolar bone loss. Other investigators have found similar results.7-9 Adriaens et al.‘O compared the long cone and orthopantomographic techniques and found greater accuracy with the long cone technique. They also studied intraexaminer reliability and interexaminer objectivity and in both cases found a high correlation coefficient and differences that were not statistically significant. Steen ” developed a device for repositioning the inferior border of the mandible for long-term follow-up evaluation of alveolar bone resorption. Chomenko* compared the Panorex, Orthopantomograph, and Panelipse and found enlargement of the image in the incisor region-25% for both the Panorex and Panelipse and 43% for the Orthopantomograph. However, he found that image distortion was greatest in the horizontal direction. For implant surgery, the optimal technique would allow measurement of the anterior alveolar ridge to within 1.0 mm of accuracy and would also permit assessment of alveolar width and alveolar inclination. It would also be advantageous to have a technique that is readily implementable in the offices of most practitioners using the usual radiographic
Most clinicians would agree that radiographs are necessary for the evaluation of patients who need implant surgery. In addition to the assessment of the type of implant that should be placed, measurements are necessary to guide in the selection of implant length. Many implants also require at least 5.5 mm of crestal alveolar bone width for successful placement.] A panoramic radiograph will allow observation of gross abnormalities and will permit assessment of alveolar bone height in the mandibular midline. However, it will not allow observation of mandibular width or mandibular inclination in the sagittal plane at the symphysis, and it produces magnification.* Fr6hlich,3 in his review of radiographic interpretation of the marginal periodontal anatomy, concluded that the greater the angle between the film and the long axis of the tooth, the greater would be the difference between the buccal and lingual alveolar crest areas on the film. He recommended the right angle or parallel radiographic technique. Lundqvist et a1.4 used acrylic splints to fix patients’ jaws so that radiography could be repeated several months later. They measured the position of the alveolar crest from the incisal edges of the teeth and found a standard deviation of 0.13 mm. Regan and Mitchell,’ using the bisection-of-the-
From the School of Dental Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania. * Assistant Professor, Department of Prosthodontics. t Clinical Professor, Department of Prosthodontics. f Professor and Director, Learning Resources. Address correspondence and reprint requests to Dr. Hadeed: Department of Prosthodontics, School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA 15261.
188
HADEEDETAL
189
190
equipment. technique.
ANTERIOR
The following report describes
such a
Materials and Methods A parallel film holder with measuring calipers was assembled for this study. In consisted of a holder for occlusal film at one end and a docking guide for the long cone of a periapical radiograph machine (Fig. 1). At the center of the device is a vertically sliding caliper and scale with two spherical balls at either end (Fig. 2). The film holder, docking device, and ball caliper are parallel to each other to ensure a right angle technique (Fig. 1). In clinical use, the inferior ball is positioned under the patient’s chin and the superior ball intraorally on the alveolar mucosa and tightened for stability (Fig. 3). The handle is then guided by the operator so that the patient holds it in the midsagittal plane (Fig. 4). Four human dry specimen mandibles were ob-
MANDIBULAR
HEIGHT DETERMINATION
tained for the purposes of this study. Two of the mandibles were sectioned at the midline to allow direct measurement at the area of the cut. Wax was used to simulate both intraoral and extraoral soft tissue (Fig. 5). Five radiographs were made of each mandible and half-mandible (Fig. 6). Each time a radiograph was made, the film holder was removed, the wax reshaped, and a notation made of the ball separation on the calipers (Fig. 7). This was done to introduce variation of placement and ball separation. Kodak ultraspeed occlusal film, size 4, was exposed at 0.4 seconds at 70 kVp and 15 mA, developed for 4 minutes, and fixed for 3.5 minutes at 72°F. After drying, the films were measured for the amount of ball separation. The amount of ball separation on the film (Fig. 8) was compared with the amount used to make the radiograph on the mandible. This magnification factor then became the basis by which the mandibular height, as measured on the radiographs, was reduced to calculate the mandibular height.
191
HADEED ET AL.
FIGURE
8.
Measurement
After a total of 20 films, the calculations for mandibular height were made. The wax was then removed, and direct measurements on the mandibles were made with a Boley guage (Fig. 9). Results The measurements were recorded to the nearest 0.1 mm (Table 1). The calculated mandibular height (CMH) ranged from an error of - 1 mm below the actual mandibular height (AMH) to +0.6 mm above the AMH. The mean error with this method of radiographic interpretation was 0.3 mm. The average error expressed as a percentage of the AMH was 1.5%.
FIGURE 9.
Measurement
of actual mandibular height.
of radiograph.
Discussion A 2 x 2 analysis of variance indicates no significant difference between the actual and calculated values of mandibular height with half mandibles (nos. 1 and 4). This mean difference was 0.15 mm. However, there was a significant difference between actual and calculated values when full mandibles (nos. 2 and 3) were measured. This mean difference was 0.42 mm. Although this represents a statistical difference, in reality the 0.42-mm difference has no clinical significance. This is especially true in view of the magnification that occurs in a panoramic radiograph. The mean correlation coefficient was r = 0.97, which is statistically significant at the P < 0.01 level (correlation coefficients were r = 0.65 for half-mandibles and r = 0.99 for full mandibles). Therefore, there appears to be no significant difference between the accuracy of measurements on full mandibles and half-mandibles from a clinical standpoint. Although a magnification ratio could be calculated for this radiographic method, it would only increase the error of measurement if it is relied on for all cases. Although it may be time-consuming to calculate mandibular height mathematically, a calibrated slide rule or a log table could be devised by a manufacturer of radiographic instruments to arrive at the CMH instantly. However, this is not seen as a drawback for the precise measurement necessary for implant surgery. Because the technique is a midline calculation, measurements distal to this
192
ANTERIOR MANDIBULAR
Table I.
Direct Measurements of Mandibles*
Exposure
BSC
BSR
RMH
AMH
CMH
CMHAMH
1A 1B 1C ID IE 2A 2B 2c 2D 2E 3A 3B 3c 3D 3E 4A 4B 4c 4D 4E
30.2 29.9 26.4 24.5 28.7 30.4 30.1 30.7 29.3 29.7 26.9 26.7 26.9 25.0 25.7 28.6 28.2 28.2 27.9 28.1
39.0 37.0 34.4 31.9 37.3 38.9 39.1 39.7 37.6 38.4 34.2 33.9 34.5 32.7 33.2 36.6 35.7 35.7 35.7 36.0
32.2 31.6 32.3 32.5 31.9 34.2 34.5 34.4 34.4 34.4 27.6 27.7 28.3 28.2 28.4 31.3 31.3 31.1 30.9 31.1
24.9 24.9 24.9 24.9 24.9 26.6 26.6 26.6 26.6 26.6 22.7 22.7 22.7 22.7 22.7 24.1 24.1 24.1 24.1 24.1
24.9 25.5 24.7 25.0 24.5 26.7 26.5 26.6 26.8 26.6 21.7 21.8 22.1 21.6 21.9 24.5 24.7 24.6 24.1 24.3
0 +0.6 -0.2 +0.1 -0.4 +O.l -0.1 0 -to.2 0 -1.0 +0.9 -0.6 -0.1 -0.8 +0.4 +0.6 +0.5 0 +0.2
AE (9%) 0 2.4 0.8 0.4 1.6 0.4 0.4 0 0.8 0 4.4 4.4 2.6 0.4 3.5 1.7 2.5 2.1 0 0.8
BSC = ball separation on calipers; BSR = ball separation on radiographs; RMH = radiographic mandibular height; AMH = actual mandibular height: CMH = calculated mandibular height: CMH-AMH = difference between CMH and AMH; AE = absolute error. * To nearest 0. I ml.
region usually result in a greater alveolar height. This is because of the inferior border concavity often seen at the midline of the mandible. Summary
The technique
presented
allows calculation
of
HEIGHT DETERMINATION
mandibular height at the midline with a mean error of 0.3 mm. It requires no special radiographic devices except a right angle-measuring caliper. References I. Ledermann P: Vollprothetische Versorgung des Zahnlosen Problemunterkiefers mit Hilfe von 4 titanplasmaceschichteten. PDL-Schraubenimplantaten SSO 89: 1137. 1979 2. Chomenko A: Comparing normal pantomographic jaw anatomy. Quintessence Int 11:61, 1980 3. Frohlich E: Comparison between anatomical and radiographic interpretation of marginal paradontal disease. Paradont 12:89. 1958 4. Lundqvist C, Levin Hans-Ebbe, Johanson G: Objective periodontal recording methods. II. Photographic and roetgenographic recording of the position of the gingival and alveolar crest in relation to the teeth. D Abs 1:647, 1956 5. Regan E, Mitchell F: Roentgenographic and dissection measurements of alveolar crest height. J Am Dent Assoc 66:356, 1963 6. Bjorn H, Holmberg K: Radiographic determination of periodontal bone destruction in epidemiological research. Odont Rev (Malmo) 17:232. 1966 7. Diedrich P, Mutschelknauss R, Niebuhr G: Vergleichende Untersuchugen von Panoramorongenaufnahmen (StatusX) und intraoralen Rontgenaufnahmen. Dtsch Zahnarztl 31:450, 1976 8. Diedrich P. Erpenstein H. Die Bewertung verschiedener Rontgentechniken zur Diagnostik der Parodontopathien unter besonderer Berucksichtigung der Status X-Halbseitentechnik. Dtsch Zahnarztl 33:61. 1978 9. Mutschelknauss R, von der Ohe M: Vergleichende Untersuchungen von Panoramarontgenaufnahmen (Panorex) und enoralen Rontgenaufnahmen. Dtsch Zahnarztl 33:68. 1978 10. Adriaens PA, DeBoever J, Vande Velde F: Comparison of intra-oral long-cone paralleling radiographic surveys and orthopantomographs with special reference to the bone height. J Oral Rehabil 9:355, 1982 I I. Steen WHA: A positioning device for the edentulous mandible in extraoral radiography. J Prosth Dent 48:257, 1982.
Surg
44388-192.1986
A Method for Determining Anterior Mandibular Height Using a Radiographic Paralleling Measuring System GEORGE J. HADEED, DMD,* DONALD J. PIPKO, DMD, MSD,t AND THOMAS G. ZULLO, PhD* A parallel radiographic technique that allows calculation of mandibular height at the midline with a mean error of 0.3 mm is presented. This accuracy gives clinical confidence in the placement of endosseous implants.
angle technique, made radiographic measurements on cadavers with periapical films. Accuracy was greatest in the mandibular posterior area, followed by the maxillary anterior, mandibular anterior, and. finally, the maxillary posterior regions. The largest error was I .6 mm; fewer than 10% of the measurements had an error greater than 1.0 mm. Bjiirn and Holmberg6 analyzed bone height scores and found the intraoral technique more accurate than the orthopantomographic images. However, they cited the latter as a valuable tool for the investigation of alveolar bone loss. Other investigators have found similar results.7-9 Adriaens et al.‘O compared the long cone and orthopantomographic techniques and found greater accuracy with the long cone technique. They also studied intraexaminer reliability and interexaminer objectivity and in both cases found a high correlation coefficient and differences that were not statistically significant. Steen ” developed a device for repositioning the inferior border of the mandible for long-term follow-up evaluation of alveolar bone resorption. Chomenko* compared the Panorex, Orthopantomograph, and Panelipse and found enlargement of the image in the incisor region-25% for both the Panorex and Panelipse and 43% for the Orthopantomograph. However, he found that image distortion was greatest in the horizontal direction. For implant surgery, the optimal technique would allow measurement of the anterior alveolar ridge to within 1.0 mm of accuracy and would also permit assessment of alveolar width and alveolar inclination. It would also be advantageous to have a technique that is readily implementable in the offices of most practitioners using the usual radiographic
Most clinicians would agree that radiographs are necessary for the evaluation of patients who need implant surgery. In addition to the assessment of the type of implant that should be placed, measurements are necessary to guide in the selection of implant length. Many implants also require at least 5.5 mm of crestal alveolar bone width for successful placement.] A panoramic radiograph will allow observation of gross abnormalities and will permit assessment of alveolar bone height in the mandibular midline. However, it will not allow observation of mandibular width or mandibular inclination in the sagittal plane at the symphysis, and it produces magnification.* Fr6hlich,3 in his review of radiographic interpretation of the marginal periodontal anatomy, concluded that the greater the angle between the film and the long axis of the tooth, the greater would be the difference between the buccal and lingual alveolar crest areas on the film. He recommended the right angle or parallel radiographic technique. Lundqvist et a1.4 used acrylic splints to fix patients’ jaws so that radiography could be repeated several months later. They measured the position of the alveolar crest from the incisal edges of the teeth and found a standard deviation of 0.13 mm. Regan and Mitchell,’ using the bisection-of-the-
From the School of Dental Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania. * Assistant Professor, Department of Prosthodontics. t Clinical Professor, Department of Prosthodontics. f Professor and Director, Learning Resources. Address correspondence and reprint requests to Dr. Hadeed: Department of Prosthodontics, School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA 15261.
188
HADEEDETAL
189
190
equipment. technique.
ANTERIOR
The following report describes
such a
Materials and Methods A parallel film holder with measuring calipers was assembled for this study. In consisted of a holder for occlusal film at one end and a docking guide for the long cone of a periapical radiograph machine (Fig. 1). At the center of the device is a vertically sliding caliper and scale with two spherical balls at either end (Fig. 2). The film holder, docking device, and ball caliper are parallel to each other to ensure a right angle technique (Fig. 1). In clinical use, the inferior ball is positioned under the patient’s chin and the superior ball intraorally on the alveolar mucosa and tightened for stability (Fig. 3). The handle is then guided by the operator so that the patient holds it in the midsagittal plane (Fig. 4). Four human dry specimen mandibles were ob-
MANDIBULAR
HEIGHT DETERMINATION
tained for the purposes of this study. Two of the mandibles were sectioned at the midline to allow direct measurement at the area of the cut. Wax was used to simulate both intraoral and extraoral soft tissue (Fig. 5). Five radiographs were made of each mandible and half-mandible (Fig. 6). Each time a radiograph was made, the film holder was removed, the wax reshaped, and a notation made of the ball separation on the calipers (Fig. 7). This was done to introduce variation of placement and ball separation. Kodak ultraspeed occlusal film, size 4, was exposed at 0.4 seconds at 70 kVp and 15 mA, developed for 4 minutes, and fixed for 3.5 minutes at 72°F. After drying, the films were measured for the amount of ball separation. The amount of ball separation on the film (Fig. 8) was compared with the amount used to make the radiograph on the mandible. This magnification factor then became the basis by which the mandibular height, as measured on the radiographs, was reduced to calculate the mandibular height.
191
HADEED ET AL.
FIGURE
8.
Measurement
After a total of 20 films, the calculations for mandibular height were made. The wax was then removed, and direct measurements on the mandibles were made with a Boley guage (Fig. 9). Results The measurements were recorded to the nearest 0.1 mm (Table 1). The calculated mandibular height (CMH) ranged from an error of - 1 mm below the actual mandibular height (AMH) to +0.6 mm above the AMH. The mean error with this method of radiographic interpretation was 0.3 mm. The average error expressed as a percentage of the AMH was 1.5%.
FIGURE 9.
Measurement
of actual mandibular height.
of radiograph.
Discussion A 2 x 2 analysis of variance indicates no significant difference between the actual and calculated values of mandibular height with half mandibles (nos. 1 and 4). This mean difference was 0.15 mm. However, there was a significant difference between actual and calculated values when full mandibles (nos. 2 and 3) were measured. This mean difference was 0.42 mm. Although this represents a statistical difference, in reality the 0.42-mm difference has no clinical significance. This is especially true in view of the magnification that occurs in a panoramic radiograph. The mean correlation coefficient was r = 0.97, which is statistically significant at the P < 0.01 level (correlation coefficients were r = 0.65 for half-mandibles and r = 0.99 for full mandibles). Therefore, there appears to be no significant difference between the accuracy of measurements on full mandibles and half-mandibles from a clinical standpoint. Although a magnification ratio could be calculated for this radiographic method, it would only increase the error of measurement if it is relied on for all cases. Although it may be time-consuming to calculate mandibular height mathematically, a calibrated slide rule or a log table could be devised by a manufacturer of radiographic instruments to arrive at the CMH instantly. However, this is not seen as a drawback for the precise measurement necessary for implant surgery. Because the technique is a midline calculation, measurements distal to this
192
ANTERIOR MANDIBULAR
Table I.
Direct Measurements of Mandibles*
Exposure
BSC
BSR
RMH
AMH
CMH
CMHAMH
1A 1B 1C ID IE 2A 2B 2c 2D 2E 3A 3B 3c 3D 3E 4A 4B 4c 4D 4E
30.2 29.9 26.4 24.5 28.7 30.4 30.1 30.7 29.3 29.7 26.9 26.7 26.9 25.0 25.7 28.6 28.2 28.2 27.9 28.1
39.0 37.0 34.4 31.9 37.3 38.9 39.1 39.7 37.6 38.4 34.2 33.9 34.5 32.7 33.2 36.6 35.7 35.7 35.7 36.0
32.2 31.6 32.3 32.5 31.9 34.2 34.5 34.4 34.4 34.4 27.6 27.7 28.3 28.2 28.4 31.3 31.3 31.1 30.9 31.1
24.9 24.9 24.9 24.9 24.9 26.6 26.6 26.6 26.6 26.6 22.7 22.7 22.7 22.7 22.7 24.1 24.1 24.1 24.1 24.1
24.9 25.5 24.7 25.0 24.5 26.7 26.5 26.6 26.8 26.6 21.7 21.8 22.1 21.6 21.9 24.5 24.7 24.6 24.1 24.3
0 +0.6 -0.2 +0.1 -0.4 +O.l -0.1 0 -to.2 0 -1.0 +0.9 -0.6 -0.1 -0.8 +0.4 +0.6 +0.5 0 +0.2
AE (9%) 0 2.4 0.8 0.4 1.6 0.4 0.4 0 0.8 0 4.4 4.4 2.6 0.4 3.5 1.7 2.5 2.1 0 0.8
BSC = ball separation on calipers; BSR = ball separation on radiographs; RMH = radiographic mandibular height; AMH = actual mandibular height: CMH = calculated mandibular height: CMH-AMH = difference between CMH and AMH; AE = absolute error. * To nearest 0. I ml.
region usually result in a greater alveolar height. This is because of the inferior border concavity often seen at the midline of the mandible. Summary
The technique
presented
allows calculation
of
HEIGHT DETERMINATION
mandibular height at the midline with a mean error of 0.3 mm. It requires no special radiographic devices except a right angle-measuring caliper. References I. Ledermann P: Vollprothetische Versorgung des Zahnlosen Problemunterkiefers mit Hilfe von 4 titanplasmaceschichteten. PDL-Schraubenimplantaten SSO 89: 1137. 1979 2. Chomenko A: Comparing normal pantomographic jaw anatomy. Quintessence Int 11:61, 1980 3. Frohlich E: Comparison between anatomical and radiographic interpretation of marginal paradontal disease. Paradont 12:89. 1958 4. Lundqvist C, Levin Hans-Ebbe, Johanson G: Objective periodontal recording methods. II. Photographic and roetgenographic recording of the position of the gingival and alveolar crest in relation to the teeth. D Abs 1:647, 1956 5. Regan E, Mitchell F: Roentgenographic and dissection measurements of alveolar crest height. J Am Dent Assoc 66:356, 1963 6. Bjorn H, Holmberg K: Radiographic determination of periodontal bone destruction in epidemiological research. Odont Rev (Malmo) 17:232. 1966 7. Diedrich P, Mutschelknauss R, Niebuhr G: Vergleichende Untersuchugen von Panoramorongenaufnahmen (StatusX) und intraoralen Rontgenaufnahmen. Dtsch Zahnarztl 31:450, 1976 8. Diedrich P. Erpenstein H. Die Bewertung verschiedener Rontgentechniken zur Diagnostik der Parodontopathien unter besonderer Berucksichtigung der Status X-Halbseitentechnik. Dtsch Zahnarztl 33:61. 1978 9. Mutschelknauss R, von der Ohe M: Vergleichende Untersuchungen von Panoramarontgenaufnahmen (Panorex) und enoralen Rontgenaufnahmen. Dtsch Zahnarztl 33:68. 1978 10. Adriaens PA, DeBoever J, Vande Velde F: Comparison of intra-oral long-cone paralleling radiographic surveys and orthopantomographs with special reference to the bone height. J Oral Rehabil 9:355, 1982 I I. Steen WHA: A positioning device for the edentulous mandible in extraoral radiography. J Prosth Dent 48:257, 1982.