Relationship of the incisive papilla to the maxillary central incisors Harold R. Ortman, D.D.S.,*
and Ding H. Tsao, D.D.S.**
State University of New York at Buffalo, School of Dentistry, School of Dentistry, Richmond, Va.
lh e incisive papilla has been used as an anatomic landmark to arrange maxillary anterior artificial teeth in complete denture prostheses. McGee’ stated that the average distance between the anterior point of the central incisors and the center of the incisive papilla is 7.7 mm. Lynn? emphasized the significance of anatomic landmarks in complete denture service. Schiffman” stated that in “. . .92.1% of 507 casts the line connecting the tips of the upper canines was within an area of 1 mm anterior and posterior to the center of the incisive papilla.” Krajicek’ suggested that the upper central incisors be set anterior to the incisive papilla to simulate the natural appearance. Watts stated, “The average distance from the middle of the incisive papilla to the middle of the labial surface of the upper central incisor is approximately 10 mm; it is seldom less than 8 mm.” Linear measurements between two objects in a three-dimensional relationship imposes special problems when the objects are not aligned on the same plane. The purpose of this article is to develop a method to overcome this difficulty and obtain improved statistical data. MATERIAL
AND
METHOD
The sophomore students of the restorative technique course at the State University of New York at Buffalo, School of Dentistry, made upper and lower alginate (irreversible hydrocolloid) impressions of each other. Die-stone casts were poured immediately. Casts were collected and numbered at random, and 38 maxillary casts were gathered for this study. A bronze frame was designed to orient each cast in
Buffalo, N. Y., and Medical College of Virginia,
a consistent position and facilitate subsequent The frame was a rectangular, boxmeasurings. shaped jig without a top and bottom (Fig. 1). Three small holes were drilled at selected sites on three sides of the frame. A straight stainless steel pin was inserted into each of these holes. The holes were located so that the plane formed by the tips of the three pins held in the holes was parallel to the plane formed by the top and bottom edges of the frame no matter how far the pins were inserted. Three screws were also attached to the frame for securing the stone cast in the desired position. The tips of the interdental papillae between maxillary central incisors and the maxillary first and second molars on the right side and the left side were chosen to serve as the reference points on the cast. By adjusting the amount of insertion of the three pins, each stone cast could be oriented in such a position inside the jig that the tips of the three pins were just in contact with their respective reference points on the stone casts. Once the cast was placed in the desired position the screws were gently tightened, and the cast was securely suspended inside the jig (Fig. 2). A thin mixture of plaster of Paris was placed on a flat fiberglass plate. With a jiggling movement, the jig (with a cast securely suspended inside) was placed directly on the top of the plaster mixture (Fig. 3). The top edges of the frame were tapped lightly to seat the bottom edges of the jig uniformly in contact with the glass plate. After the plaster had set, the jig was removed. The stone cast was then mounted on a plaster base with the plane formed by the reference points parallel to the bottom surface of the base. Each of the casts was mounted this way (Fig. 3).
MEASUREMENT *Professor and Chairman, Department of Removable Prosthodontics. **Assistant Professor, Department of Removable Prosthodontics.
492
NOVEMBER
1979
VOLUME
42
NUMBER
5
AND CORRECTION
The “horizontal” distances were measured with a profile projection measure composed of a set of lenses with a magnifying power of 10 (Fig. 4). Each cast
0022-3913/79/110492
+ 05$00.50/O 0 1979 The C. V. Moshy Co.
RELATIONSHIP
OF INCISIVE
PAPILLA
TO MAXILLARY
CENTRAL
was placed with its plaster base on the measuring table so that the right reference point on the cast coincided with the intersection point of the cross on the screen of the measurer, and the left reference point was on the horizontal arm of the cross while both scales were set at “0” readings. Anteriorposterior distances were read by moving the table anteriorly and posteriorly. Cross-arch distances were measured by moving the table from right to left (Fig. 4). Every reading was repeated five times and the average of the five readings was recorded. The “vertical” dimensions were obtained from a dial gauge supported by a brass rod machined to fit into the cross-arm of a Ney* surveyor. The height of the incisors was read by putting the measuring rod on the highest point of the incisal edge while the plaster base was lying flat on the survey table (Fig. 5). The highest point of the incisive papilla was always the most anterior point of its anterior border. Every reading was repeated five times and the average of the five readings was recorded. The heights of the three reference points were also recorded to serve as a double check to see whether the bottom surface of the plaster base was parallel to the reference plane. In other words, if the three reference points were not the same height, there would be inconsistency of the reference plane.
INCISORS
Fig. 1. The frame.
bronze
orientation
jig and surrounding
RESULTS Most incisive papillae examined were pear shaped, with their slender ends pointing at the anterior reference point between maxillary central incisors. Oval shapes were the next most frequent. One cast showed no trace of this anatomic structure (Table I). The mean distance between the most anterior point of the maxillary central incisors and the posterior border of the incisive papilla was 12.454 mm with a standard deviation of 3.867 mm. The average error due to the inconsistency of the method of mounting and measuring was less than 3%. Thirty casts were measured. Figs. 6 to 8 show the details of the landmarks used and the measurement statistics in millimeters. DISCUSSION Tips of interdental papillae were used as reference points based on an assumption that the plane formed by these points would be closely parallel to the plane formed by the corresponding portions of the edentu*J. M. Ney Co., Hartford,
THE JOURNAL
Conn.
OF PROSTHETIC
DENTISTRY
Fig. 2. A maxillary the jig.
stone cast securely suspended inside
lous alveolar ridge crest. This may not be true in a given clinical situation, but in most instances it is believed that some correlation of the planes exists in a sense of normal statistical distribution. All the measurements are straight linear distances in millimeters which are either parallel (“horizontal”) or perpendicular (“height”) to the reference plane maintained by the flat bottom surface of the plaster base. In other words, they are the measurements of the orthographic projections of the relationship between the maxillary centric incisors and the incisive papilla to the reference plane. The axial and rotations of the incisors are angulations ignored. The results of this study are accurate enough to
493
ORTMAN
AND TSAO
Fig. 3. Building up the plaster base. Left, The jig with the stone cast inside was placed on a thin mixture of plaster of Paris. Right, The frame was removed after the plaster of Paris had set. Notice that the stone cast was built into the plaster mount base.
Fig. 4. Measuring the “horizontal”
distances. Left, The profile projection measurer. Right, Reading at the most posterior point of the incisive papilla. have clinical application if the above assumption and its limitations are fully recognized. Because the standard deviation of this study is relatively greater than expected, the average dimensional relations should not be overemphasized in arranging anterior denture teeth for a given patient. Nevertheless, the statistical data may provide a good starting point for contour-wax occlusion rims. The data can also be used as a reliable guide for setting the maxillary
494
central incisors clinically and checking the position of the maxillary incisors for esthetic and phonetic requirements in the trial wax denture. When the teeth have been set by the laboratory technician according to the work authorization, the dentist can apply these measurements to judge the conformation and position of the artificial maxillary incisors. In this study the most anterior and posterior
NOVEMBER
1979
VOLUME
42
NUMBER
5
RELATIONSHIP
OF INCISIVE
PAPILLA
TO MAXILLARY
CENTRAL
INCISORS
Fig. 7. Average anatomic relation between the papilla and the maxillary central incisors. Sagittal al view. A, Anterior reference point. apa, Most point of the incisive papilla. app, Most posterior the incisive papilla.
Fig. 5. Measuring the “vertical” height measurer.
incisive sectionanterior point of
dimensions with a Ney
‘+
18.072 -+8.8#6
I
Fig. 8. Average anatomic relation between the incisive papilla and the maxillary central incisors, frontal view. A, Anterior reference point. R, Right reference. L, Left reference point. The plane formed by point A, R, L is the reference plane used in this study.
3.422
3”
points rather than the center point of the incisive papilla were used as anatomic boundaries in all “horizontal” measurements because they could be easily and exactly located. In some cases the papillae blended into surrounding soft tissue so well that no apparent demarcation could be traced. These casts were discarded.
SUMMARY Fig. 6. Average anatomic relation between the incisive papilla and the maxillary central incisors, occlusal view. A, Anterior reference point. R, Right reference point. L, Left reference point. A’, Intersection of RL and A, which is perpendicular to RL.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
The average distance between the most anterior point of the maxillary central incisors and the most posterior point of the incisive papilla was 12.454 mm with a standard deviation of 3.867 mm. This distance was measured when these two points were
495
ORTMAN
Table I. Classification
of the anatomic
shapes of
AND TSAO
the right side (R), and on the left side (L). The
iE0. OBSERVED
PERCENT
Pear
21
55.26
Oval
7
18.42
average error incurred due to inconsistency of the method employed was less than 3% or less than 0.372 mm for the position of the central incisor. It is believed that the application of this anatomic relation can provide a reliable point for arranging and checking the position of the anterior maxillary teeth for complete dentures.
Irregular
4
10.52
REFERENCES
Rectangular
3
7.89
Triangular
I
2.63
Inverted Pear
I
2.63
incisive
papilla
ANATOMICAL
SHAPES
1. McGee, G. F.: Tooth placement and base contour in denture construction. J PROSTHET DENT 10~651, 1960 2. Lynn, B. D.: The significance of anatomic landmarks in complete denture service. J PROSTHET DENT 14456, 1964. 3. Schiffman, P.: Relation of maxillary canines to the incisive papilla. J PROSTHET DENT 14:469, 1964. 4. Krajicek, D.: Simulation of natural appearance. J PROSTHET DENT 12:30,
5.
No Papilla TOTAL
I
2.63
38
100
1962.
Watt, M. D.: Designing Complete Dentures. Philadelphia, 1976, W. B. Saunders Co.
Reprint requeststo: DR. HAROLDR. ORPMAN STATE UNIVERSITY OF NEW YORK AT BUFFALO SCHOOL OF DENTISTRY
projected on a plane which was parallel to the reference plane formed by the tips of three interdental papillae; i.e., the papilla between two central incisors (A), between the first and second molars on
BUFFALO, N. Y. 14214
Journal adopts new policy for illustrations
in color
The Editorial Council and publisher of THE JOURNAL OF PROSTHETIC DENTISTRYhave agreed to publish articles that contain color illustrations at a reduced cost to authors. Authors will pay only $225 per color page, or part thereof, and can present from one to eight illustrations on each page. Two high-quality 35 mm color transparencies (an original and duplicate) must be submitted for each illustration, and manuscript length cannot exceed 10 to 12 double-spaced typewritten pages. The Editor and his reviewers have final authority to determine if color illustrations afford the most effective presentation. Articles containing color will appear in selected issues beginning in 1980. Authors are requested to include a statement when they submit their manuscript agreeing to pay $225 for each page of color. Billing will come from the publisher after the author has approved color proofs and the article is scheduled for publication. Manuscripts and illustrations will be accepted immediately for evaluation.
496
NOVEMBER
1979
VOLUME
42
NUMBER
5
and Ding H. Tsao, D.D.S.**
State University of New York at Buffalo, School of Dentistry, School of Dentistry, Richmond, Va.
lh e incisive papilla has been used as an anatomic landmark to arrange maxillary anterior artificial teeth in complete denture prostheses. McGee’ stated that the average distance between the anterior point of the central incisors and the center of the incisive papilla is 7.7 mm. Lynn? emphasized the significance of anatomic landmarks in complete denture service. Schiffman” stated that in “. . .92.1% of 507 casts the line connecting the tips of the upper canines was within an area of 1 mm anterior and posterior to the center of the incisive papilla.” Krajicek’ suggested that the upper central incisors be set anterior to the incisive papilla to simulate the natural appearance. Watts stated, “The average distance from the middle of the incisive papilla to the middle of the labial surface of the upper central incisor is approximately 10 mm; it is seldom less than 8 mm.” Linear measurements between two objects in a three-dimensional relationship imposes special problems when the objects are not aligned on the same plane. The purpose of this article is to develop a method to overcome this difficulty and obtain improved statistical data. MATERIAL
AND
METHOD
The sophomore students of the restorative technique course at the State University of New York at Buffalo, School of Dentistry, made upper and lower alginate (irreversible hydrocolloid) impressions of each other. Die-stone casts were poured immediately. Casts were collected and numbered at random, and 38 maxillary casts were gathered for this study. A bronze frame was designed to orient each cast in
Buffalo, N. Y., and Medical College of Virginia,
a consistent position and facilitate subsequent The frame was a rectangular, boxmeasurings. shaped jig without a top and bottom (Fig. 1). Three small holes were drilled at selected sites on three sides of the frame. A straight stainless steel pin was inserted into each of these holes. The holes were located so that the plane formed by the tips of the three pins held in the holes was parallel to the plane formed by the top and bottom edges of the frame no matter how far the pins were inserted. Three screws were also attached to the frame for securing the stone cast in the desired position. The tips of the interdental papillae between maxillary central incisors and the maxillary first and second molars on the right side and the left side were chosen to serve as the reference points on the cast. By adjusting the amount of insertion of the three pins, each stone cast could be oriented in such a position inside the jig that the tips of the three pins were just in contact with their respective reference points on the stone casts. Once the cast was placed in the desired position the screws were gently tightened, and the cast was securely suspended inside the jig (Fig. 2). A thin mixture of plaster of Paris was placed on a flat fiberglass plate. With a jiggling movement, the jig (with a cast securely suspended inside) was placed directly on the top of the plaster mixture (Fig. 3). The top edges of the frame were tapped lightly to seat the bottom edges of the jig uniformly in contact with the glass plate. After the plaster had set, the jig was removed. The stone cast was then mounted on a plaster base with the plane formed by the reference points parallel to the bottom surface of the base. Each of the casts was mounted this way (Fig. 3).
MEASUREMENT *Professor and Chairman, Department of Removable Prosthodontics. **Assistant Professor, Department of Removable Prosthodontics.
492
NOVEMBER
1979
VOLUME
42
NUMBER
5
AND CORRECTION
The “horizontal” distances were measured with a profile projection measure composed of a set of lenses with a magnifying power of 10 (Fig. 4). Each cast
0022-3913/79/110492
+ 05$00.50/O 0 1979 The C. V. Moshy Co.
RELATIONSHIP
OF INCISIVE
PAPILLA
TO MAXILLARY
CENTRAL
was placed with its plaster base on the measuring table so that the right reference point on the cast coincided with the intersection point of the cross on the screen of the measurer, and the left reference point was on the horizontal arm of the cross while both scales were set at “0” readings. Anteriorposterior distances were read by moving the table anteriorly and posteriorly. Cross-arch distances were measured by moving the table from right to left (Fig. 4). Every reading was repeated five times and the average of the five readings was recorded. The “vertical” dimensions were obtained from a dial gauge supported by a brass rod machined to fit into the cross-arm of a Ney* surveyor. The height of the incisors was read by putting the measuring rod on the highest point of the incisal edge while the plaster base was lying flat on the survey table (Fig. 5). The highest point of the incisive papilla was always the most anterior point of its anterior border. Every reading was repeated five times and the average of the five readings was recorded. The heights of the three reference points were also recorded to serve as a double check to see whether the bottom surface of the plaster base was parallel to the reference plane. In other words, if the three reference points were not the same height, there would be inconsistency of the reference plane.
INCISORS
Fig. 1. The frame.
bronze
orientation
jig and surrounding
RESULTS Most incisive papillae examined were pear shaped, with their slender ends pointing at the anterior reference point between maxillary central incisors. Oval shapes were the next most frequent. One cast showed no trace of this anatomic structure (Table I). The mean distance between the most anterior point of the maxillary central incisors and the posterior border of the incisive papilla was 12.454 mm with a standard deviation of 3.867 mm. The average error due to the inconsistency of the method of mounting and measuring was less than 3%. Thirty casts were measured. Figs. 6 to 8 show the details of the landmarks used and the measurement statistics in millimeters. DISCUSSION Tips of interdental papillae were used as reference points based on an assumption that the plane formed by these points would be closely parallel to the plane formed by the corresponding portions of the edentu*J. M. Ney Co., Hartford,
THE JOURNAL
Conn.
OF PROSTHETIC
DENTISTRY
Fig. 2. A maxillary the jig.
stone cast securely suspended inside
lous alveolar ridge crest. This may not be true in a given clinical situation, but in most instances it is believed that some correlation of the planes exists in a sense of normal statistical distribution. All the measurements are straight linear distances in millimeters which are either parallel (“horizontal”) or perpendicular (“height”) to the reference plane maintained by the flat bottom surface of the plaster base. In other words, they are the measurements of the orthographic projections of the relationship between the maxillary centric incisors and the incisive papilla to the reference plane. The axial and rotations of the incisors are angulations ignored. The results of this study are accurate enough to
493
ORTMAN
AND TSAO
Fig. 3. Building up the plaster base. Left, The jig with the stone cast inside was placed on a thin mixture of plaster of Paris. Right, The frame was removed after the plaster of Paris had set. Notice that the stone cast was built into the plaster mount base.
Fig. 4. Measuring the “horizontal”
distances. Left, The profile projection measurer. Right, Reading at the most posterior point of the incisive papilla. have clinical application if the above assumption and its limitations are fully recognized. Because the standard deviation of this study is relatively greater than expected, the average dimensional relations should not be overemphasized in arranging anterior denture teeth for a given patient. Nevertheless, the statistical data may provide a good starting point for contour-wax occlusion rims. The data can also be used as a reliable guide for setting the maxillary
494
central incisors clinically and checking the position of the maxillary incisors for esthetic and phonetic requirements in the trial wax denture. When the teeth have been set by the laboratory technician according to the work authorization, the dentist can apply these measurements to judge the conformation and position of the artificial maxillary incisors. In this study the most anterior and posterior
NOVEMBER
1979
VOLUME
42
NUMBER
5
RELATIONSHIP
OF INCISIVE
PAPILLA
TO MAXILLARY
CENTRAL
INCISORS
Fig. 7. Average anatomic relation between the papilla and the maxillary central incisors. Sagittal al view. A, Anterior reference point. apa, Most point of the incisive papilla. app, Most posterior the incisive papilla.
Fig. 5. Measuring the “vertical” height measurer.
incisive sectionanterior point of
dimensions with a Ney
‘+
18.072 -+8.8#6
I
Fig. 8. Average anatomic relation between the incisive papilla and the maxillary central incisors, frontal view. A, Anterior reference point. R, Right reference. L, Left reference point. The plane formed by point A, R, L is the reference plane used in this study.
3.422
3”
points rather than the center point of the incisive papilla were used as anatomic boundaries in all “horizontal” measurements because they could be easily and exactly located. In some cases the papillae blended into surrounding soft tissue so well that no apparent demarcation could be traced. These casts were discarded.
SUMMARY Fig. 6. Average anatomic relation between the incisive papilla and the maxillary central incisors, occlusal view. A, Anterior reference point. R, Right reference point. L, Left reference point. A’, Intersection of RL and A, which is perpendicular to RL.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
The average distance between the most anterior point of the maxillary central incisors and the most posterior point of the incisive papilla was 12.454 mm with a standard deviation of 3.867 mm. This distance was measured when these two points were
495
ORTMAN
Table I. Classification
of the anatomic
shapes of
AND TSAO
the right side (R), and on the left side (L). The
iE0. OBSERVED
PERCENT
Pear
21
55.26
Oval
7
18.42
average error incurred due to inconsistency of the method employed was less than 3% or less than 0.372 mm for the position of the central incisor. It is believed that the application of this anatomic relation can provide a reliable point for arranging and checking the position of the anterior maxillary teeth for complete dentures.
Irregular
4
10.52
REFERENCES
Rectangular
3
7.89
Triangular
I
2.63
Inverted Pear
I
2.63
incisive
papilla
ANATOMICAL
SHAPES
1. McGee, G. F.: Tooth placement and base contour in denture construction. J PROSTHET DENT 10~651, 1960 2. Lynn, B. D.: The significance of anatomic landmarks in complete denture service. J PROSTHET DENT 14456, 1964. 3. Schiffman, P.: Relation of maxillary canines to the incisive papilla. J PROSTHET DENT 14:469, 1964. 4. Krajicek, D.: Simulation of natural appearance. J PROSTHET DENT 12:30,
5.
No Papilla TOTAL
I
2.63
38
100
1962.
Watt, M. D.: Designing Complete Dentures. Philadelphia, 1976, W. B. Saunders Co.
Reprint requeststo: DR. HAROLDR. ORPMAN STATE UNIVERSITY OF NEW YORK AT BUFFALO SCHOOL OF DENTISTRY
projected on a plane which was parallel to the reference plane formed by the tips of three interdental papillae; i.e., the papilla between two central incisors (A), between the first and second molars on
BUFFALO, N. Y. 14214
Journal adopts new policy for illustrations
in color
The Editorial Council and publisher of THE JOURNAL OF PROSTHETIC DENTISTRYhave agreed to publish articles that contain color illustrations at a reduced cost to authors. Authors will pay only $225 per color page, or part thereof, and can present from one to eight illustrations on each page. Two high-quality 35 mm color transparencies (an original and duplicate) must be submitted for each illustration, and manuscript length cannot exceed 10 to 12 double-spaced typewritten pages. The Editor and his reviewers have final authority to determine if color illustrations afford the most effective presentation. Articles containing color will appear in selected issues beginning in 1980. Authors are requested to include a statement when they submit their manuscript agreeing to pay $225 for each page of color. Billing will come from the publisher after the author has approved color proofs and the article is scheduled for publication. Manuscripts and illustrations will be accepted immediately for evaluation.
496
NOVEMBER
1979
VOLUME
42
NUMBER
5
