- Email: [email protected]
Arrangement of artificial teeth in abnormal jaw relations: Maxillary protrusion and wider upper arch
Arrangement
of artificial
relations: Maxillary upper arch
teeth
protrusion
in abnormal and
iaw
wider
and K. Bhargava, B.D.S., MS.** B. K. Goyal, B.D.S., M.D.S.,* Government Dental College and Hospital, Ahmedabad, Gujarat, India
M
ost tooth setups are taught and done on casts with normal ridge relationships. There are times when the dentist is called upon to arrange teeth for abnormal ridge relationships. He then finds himself at a loss to cope. He fails to understand how he can change the normal guidelines (such as individual positions and inclinations of teeth, their rotational positions, horizontal and vertical overlap, and the like) to suit the demands of the new ridge relations. An effort is made in this article to offer guidance in the management of tooth arrangement in abnormal jaw relations. RIDGE RELATIONSHIPS Definition of normal ridge
relationship
The maxillary and mandibular ridges are considered to be in normal relation when, in centric relation, the upper ridge in the anterior region is slightly labial to the lower ridge (Fig. 1, A) and when, in the posterior region, the interalveolar crest line between two ridges forms an 80 degree angle to a horizontal plane, i.e., the crest of the lower ridge is slightly buccal to that of the upper ridge1 (Fig. 1, B). Definition
of abnormal
ridge
relationship
Any deviation in the anterior and/or posterior region from the normal ridge relationship is considered abnormal. In the anterior region. The ridge relationship is abnormal: (a) when the upper ridge is located much further anteriorly than the lower ridge, i.e., maxillary protrusion; and (b) when the upper ridge is located in the same line as or lingual to the lower ridge, i.e., mandibular protrusion or prognathism (Fig. 2, A). *Lecturer, Department of Prosthetics. **Senior Professor in charge of the Department
of Prosthetics. 107
108
Goyal
and Bhargava
.J. t’t o\thet. Dent. .Iuly, 1974
A Fig.
1. Normal
ridge
relation:
A, anterior
region:
B, Posterior
region.
In the posterior region. Abnormality is considered to exist: (a) when the crest of the lower ridge is placed lingual to that of the upper ridge, i.e., a wider upper arch; and (b) when the crest of the lower ridge is placed much further buccall! than normal in relation to that of the upper arch, i.e., a wider lower than upper arch (Fig. 2, B) . All of these variations may range from a slight to a marked degree. Though all four situations can exist independently of the others, or sometimes even unilaterally, usually a wider upper arch is associated with maxillary protrusion and a wider mandibular arch with mandibular protrusion. Therefore, for the sake of clarity, it is well to discuss the management of the abnormalities in the anterior and posterior regions together, in each of these two categories. Arrangement Arrangement
of teeth
in abnormal
ridge
relations
of anterior teeth in maxillary protrusion. 1. As the upper arch in these situations is further forward in the anterior region, the first problem is that of an excessive amount of overjet (horizontal overlap) which results in an abnormal upper and lower canine tooth relationship. No attempt should be made to reduce this horizontal overlap by moving the upper anterior teeth palatally or the lower anterior teeth labially. PROBLEM 2. In situations where there is a normal upper and lower canine relationship mesiodistally, the distal surface of the lower canine tooth is located at the tip of the cusp of the upper canine (Fig, 3, A). However, when the upper anterior teeth have been arranged, it may be that this relation will not be obtained when the lower anterior teeth are arranged. This discrepancy in canine relationship is the result of the upper arch being forward in relation to the lower arch so the lower anterior teeth have to be set further lingually in relation to the upper anterior teeth. This results in the lower canine tooth finishing anywhere from the tip to the distal surface of the upper canine tooth (Fig. 3, A). When the maxillary protrusion is excessive, the distal incline of the cusp of the lower canine will sometimes be posterior to the distal surface of the upper canine tooth (Fig. 3, C and D) . This canine relationship also influences the subsequent posterior arrangement of teeth. MANAGE~IENT. The management of such situations can be attempted in any of the following ways, depending upon the severity of the maxillary protrusion. ( 1) If the protrusion is not too extreme, the simplest way is to select the lower anterior teeth of a narrower mesiodistal width and try to achieve the normal canine relationship.’ PROBLEM
Artificial
b
a
teeth
in abnormal
G, maxillary
maxillary
ridge relations.
protrusion.
relations
109
c
A
Fig. 2. Abnormal
jaw
(I?)
(A) Posterior
6
Anterior region:
region: n, normal;
Q, normal; 6, wider
b, mandibular protrusion; mandibular arch; C, wider
arch.
(2) If esthetics permit, a little crowding of the lower anterior teeth by overlapping may solve the problem well.’ (3) Another solution which is effective at times is leave slight spaces between the upper anterior teeth to attain normal canine relations: However, such a procedure is esthetically limited. (4) In situations where the discrepancy is not too great, grinding of the distal surface of lower canine is sufficient to restore the normal canine relationship. This procedure can, however, be extended to all of the lower anterior teeth by grinding their mesial and distal surfaces to narrow their total mesiodistal width. But, this grinding should be done very judiciously so as not to mar the esthetics or the anatomic forms of the teeth. (5) In situations where the discrepancy is excessive and cannot be managed by the manipulation and modification of the lower anterior teeth, the lower anterior teeth must be left as they are, and the lower first premolars must be eliminated from the dental arch.” If the distal incline of the lower canine is entirely posterior to the distal surface of the upper canine tooth, the situation is ideally suited for such a procedure, and a satisfactory posterior setup can be developed (Fig. 4). If, however, the entire distal incline of the cusp of the lower canine tooth is not free for articulation with the mesial incline of the buccal cusp of the upper first premolar (Fig. 3, C) , it is well to move the lower canine slightly to achieve the proper relation with the upper premolar. The slight space thus created in the lower anterior arch is taken up by the other anterior teeth without affecting the esthetics. Sometimes slight grinding of the mesial surface of the upper first premolar will bring it into the correct relation with the lower canine. It is sometimes recommended that one of the four lower incisors be eliminated.” The validity of such a procedure is obviously open to question from the esthetic point of view, especially when a better alternative is to eliminate one of the least important teeth, such as the lower first premolar from the lower arch. Once the anterior teeth are satisfactorily arranged, the posterior teeth are arranged. If the posterior ridge relation is normal, a normal arrangement of teeth is used after the lower first premolars have been removed from the dental arch. In these situations, if the palatal cusp of the upper first premolar interferes with the lower canine, it is ground off to remove this interference. The other posterior teeth do not pose much of a problem in arrangement. Arrangement of posterior teeth when the upper arch is wider.
110
Goyal
Fig. 3. Upper
and
Fig. 4. Mesiodistal premolar Fig. The
Delit. July, 1974
.J. Plosthet.
and Bhargava
lower
canine
A, Normal;
relationship:
relationship
of upper
and
lower
relationship shows where
of upper and lower the wax is added.
B, C, and
posterior
D, in maxillary
protrusion.
after
lower
teeth
removing
first
tooth.
5. Buccolingual shaded portion
posterior
teeth
in a wider
upper
arch.
THE PROBLEM. In this situation, the lower crest of the ridge in the posterior region is lingual to the upper residual ridge. This relationship is not very common, but when present, it may give rise to considerable difficulty in the placement of upper and lower teeth in their correct occlusal relationship. In such instances, the upper arch is wider than the lower, and if the upper teeth are placed on the crest of the ridge, they will make inadequate occlusal contact with the correctly placed lower teeth. At the same time, if an attempt is made to occlude the lower teeth with the correctly placed upper teeth, the lower teeth will place too far buccally. This is much more detrimental as leading to an instability of the lower denture. the lower denture-bearing area is already very small. MANAGEMENT. The following methods of correction may be employed. (1) If the discrepancy is very slight, the upper teeth are moved slightly in a palatal direction to provide a working occlusal contact with the lower teeth.’ However, such a procedure has a very limited application as the upper posterior teeth cannot be moved inside (palatally) to any great extent without affecting phonetics and cheek support. (2) If the upper arch is much wider than the lower one, any of the following methods can be used successfully. (a) The lower posterior teeth are correctly placed on the crest of the ridge. The
Volume Numbrr
Artificial
32 1
teeth
in abnormal
jaw
relations
111
upper teeth are then set so that they occlude well with the lower teeth. Then the buccal contours are built on the upper teeth in wax which is later replaced by tooth-colored acrylic resin to fulfill esthetic requirements and to provide support for the cheek9 (Fig. 5, A). (b) Another method can be used alternatively for the same problem. The upper posterior teeth are arranged first to meet the requirements of esthetics. The lower teeth are kept on the crest of the ridge. This will result in an unfavorable occlusal relationship of the upper and lower posterior teeth. In order to establish a functional occlusal contact between the upper and lower posterior teeth, wax is added on the palatal aspect of the upper posterior teeth. This wax is later replaced by toothcolored acrylic resin. This gives a functionally effective occlusal contact as well as an esthetically acceptable buccal surface contour of the upper posterior teeth4 (Fig. 5, B). Nonanatomic posterior teeth are best for these procedures as they allow more latitude in their buccolingual placement. SUMMARY
The upper-lower ridge relationship is an individual problem for each complete denture patient. When it is normal, not much effort is needed to obtain a suitable arrangement of artificial teeth. However, when these relations are abnormal, one has to deviate from the usual procedures to achieve successful results. One aspect of the problem of abnormal ridge relations was discussed (i.e., maxillary protrusion and wider maxillary arch and its management during arrangement of artificial teeth). The two conditions are dealt with separately for the sake of clarity and better understanding of the problem. References 1. 2. 3. 4.
Nichols, I. G.: Prosthetic Dentistry, St. Louis, 1930, The C. Fenn, H. R. B., Liddelow, K. P., and Gimson, A. P.: ed. 2, London, 1961, Staples Press, p.259. Craddock, F. W.: Prosthetic Dentistry. A Clinical Outline, Kimpton, p. 186. Hardy, I. R., and Passamonti, G.: A Method of Arranging Jaw Relations, J. PROSTHET. DENT. 13: 606-610, 1963. GOVERNMENT NEW CIVIL AHMEDABAD GU JARAT,
DENTAL HOSPITAL
380016 INDIA
COLLEGE COMPOUND
V. Mosby Company, p. 337. Clinical Dental Prosthetics, ed.
3, London,
Artificial
Teeth
1956, for
Henry Class
II
of artificial
relations: Maxillary upper arch
teeth
protrusion
in abnormal and
iaw
wider
and K. Bhargava, B.D.S., MS.** B. K. Goyal, B.D.S., M.D.S.,* Government Dental College and Hospital, Ahmedabad, Gujarat, India
M
ost tooth setups are taught and done on casts with normal ridge relationships. There are times when the dentist is called upon to arrange teeth for abnormal ridge relationships. He then finds himself at a loss to cope. He fails to understand how he can change the normal guidelines (such as individual positions and inclinations of teeth, their rotational positions, horizontal and vertical overlap, and the like) to suit the demands of the new ridge relations. An effort is made in this article to offer guidance in the management of tooth arrangement in abnormal jaw relations. RIDGE RELATIONSHIPS Definition of normal ridge
relationship
The maxillary and mandibular ridges are considered to be in normal relation when, in centric relation, the upper ridge in the anterior region is slightly labial to the lower ridge (Fig. 1, A) and when, in the posterior region, the interalveolar crest line between two ridges forms an 80 degree angle to a horizontal plane, i.e., the crest of the lower ridge is slightly buccal to that of the upper ridge1 (Fig. 1, B). Definition
of abnormal
ridge
relationship
Any deviation in the anterior and/or posterior region from the normal ridge relationship is considered abnormal. In the anterior region. The ridge relationship is abnormal: (a) when the upper ridge is located much further anteriorly than the lower ridge, i.e., maxillary protrusion; and (b) when the upper ridge is located in the same line as or lingual to the lower ridge, i.e., mandibular protrusion or prognathism (Fig. 2, A). *Lecturer, Department of Prosthetics. **Senior Professor in charge of the Department
of Prosthetics. 107
108
Goyal
and Bhargava
.J. t’t o\thet. Dent. .Iuly, 1974
A Fig.
1. Normal
ridge
relation:
A, anterior
region:
B, Posterior
region.
In the posterior region. Abnormality is considered to exist: (a) when the crest of the lower ridge is placed lingual to that of the upper ridge, i.e., a wider upper arch; and (b) when the crest of the lower ridge is placed much further buccall! than normal in relation to that of the upper arch, i.e., a wider lower than upper arch (Fig. 2, B) . All of these variations may range from a slight to a marked degree. Though all four situations can exist independently of the others, or sometimes even unilaterally, usually a wider upper arch is associated with maxillary protrusion and a wider mandibular arch with mandibular protrusion. Therefore, for the sake of clarity, it is well to discuss the management of the abnormalities in the anterior and posterior regions together, in each of these two categories. Arrangement Arrangement
of teeth
in abnormal
ridge
relations
of anterior teeth in maxillary protrusion. 1. As the upper arch in these situations is further forward in the anterior region, the first problem is that of an excessive amount of overjet (horizontal overlap) which results in an abnormal upper and lower canine tooth relationship. No attempt should be made to reduce this horizontal overlap by moving the upper anterior teeth palatally or the lower anterior teeth labially. PROBLEM 2. In situations where there is a normal upper and lower canine relationship mesiodistally, the distal surface of the lower canine tooth is located at the tip of the cusp of the upper canine (Fig, 3, A). However, when the upper anterior teeth have been arranged, it may be that this relation will not be obtained when the lower anterior teeth are arranged. This discrepancy in canine relationship is the result of the upper arch being forward in relation to the lower arch so the lower anterior teeth have to be set further lingually in relation to the upper anterior teeth. This results in the lower canine tooth finishing anywhere from the tip to the distal surface of the upper canine tooth (Fig. 3, A). When the maxillary protrusion is excessive, the distal incline of the cusp of the lower canine will sometimes be posterior to the distal surface of the upper canine tooth (Fig. 3, C and D) . This canine relationship also influences the subsequent posterior arrangement of teeth. MANAGE~IENT. The management of such situations can be attempted in any of the following ways, depending upon the severity of the maxillary protrusion. ( 1) If the protrusion is not too extreme, the simplest way is to select the lower anterior teeth of a narrower mesiodistal width and try to achieve the normal canine relationship.’ PROBLEM
Artificial
b
a
teeth
in abnormal
G, maxillary
maxillary
ridge relations.
protrusion.
relations
109
c
A
Fig. 2. Abnormal
jaw
(I?)
(A) Posterior
6
Anterior region:
region: n, normal;
Q, normal; 6, wider
b, mandibular protrusion; mandibular arch; C, wider
arch.
(2) If esthetics permit, a little crowding of the lower anterior teeth by overlapping may solve the problem well.’ (3) Another solution which is effective at times is leave slight spaces between the upper anterior teeth to attain normal canine relations: However, such a procedure is esthetically limited. (4) In situations where the discrepancy is not too great, grinding of the distal surface of lower canine is sufficient to restore the normal canine relationship. This procedure can, however, be extended to all of the lower anterior teeth by grinding their mesial and distal surfaces to narrow their total mesiodistal width. But, this grinding should be done very judiciously so as not to mar the esthetics or the anatomic forms of the teeth. (5) In situations where the discrepancy is excessive and cannot be managed by the manipulation and modification of the lower anterior teeth, the lower anterior teeth must be left as they are, and the lower first premolars must be eliminated from the dental arch.” If the distal incline of the lower canine is entirely posterior to the distal surface of the upper canine tooth, the situation is ideally suited for such a procedure, and a satisfactory posterior setup can be developed (Fig. 4). If, however, the entire distal incline of the cusp of the lower canine tooth is not free for articulation with the mesial incline of the buccal cusp of the upper first premolar (Fig. 3, C) , it is well to move the lower canine slightly to achieve the proper relation with the upper premolar. The slight space thus created in the lower anterior arch is taken up by the other anterior teeth without affecting the esthetics. Sometimes slight grinding of the mesial surface of the upper first premolar will bring it into the correct relation with the lower canine. It is sometimes recommended that one of the four lower incisors be eliminated.” The validity of such a procedure is obviously open to question from the esthetic point of view, especially when a better alternative is to eliminate one of the least important teeth, such as the lower first premolar from the lower arch. Once the anterior teeth are satisfactorily arranged, the posterior teeth are arranged. If the posterior ridge relation is normal, a normal arrangement of teeth is used after the lower first premolars have been removed from the dental arch. In these situations, if the palatal cusp of the upper first premolar interferes with the lower canine, it is ground off to remove this interference. The other posterior teeth do not pose much of a problem in arrangement. Arrangement of posterior teeth when the upper arch is wider.
110
Goyal
Fig. 3. Upper
and
Fig. 4. Mesiodistal premolar Fig. The
Delit. July, 1974
.J. Plosthet.
and Bhargava
lower
canine
A, Normal;
relationship:
relationship
of upper
and
lower
relationship shows where
of upper and lower the wax is added.
B, C, and
posterior
D, in maxillary
protrusion.
after
lower
teeth
removing
first
tooth.
5. Buccolingual shaded portion
posterior
teeth
in a wider
upper
arch.
THE PROBLEM. In this situation, the lower crest of the ridge in the posterior region is lingual to the upper residual ridge. This relationship is not very common, but when present, it may give rise to considerable difficulty in the placement of upper and lower teeth in their correct occlusal relationship. In such instances, the upper arch is wider than the lower, and if the upper teeth are placed on the crest of the ridge, they will make inadequate occlusal contact with the correctly placed lower teeth. At the same time, if an attempt is made to occlude the lower teeth with the correctly placed upper teeth, the lower teeth will place too far buccally. This is much more detrimental as leading to an instability of the lower denture. the lower denture-bearing area is already very small. MANAGEMENT. The following methods of correction may be employed. (1) If the discrepancy is very slight, the upper teeth are moved slightly in a palatal direction to provide a working occlusal contact with the lower teeth.’ However, such a procedure has a very limited application as the upper posterior teeth cannot be moved inside (palatally) to any great extent without affecting phonetics and cheek support. (2) If the upper arch is much wider than the lower one, any of the following methods can be used successfully. (a) The lower posterior teeth are correctly placed on the crest of the ridge. The
Volume Numbrr
Artificial
32 1
teeth
in abnormal
jaw
relations
111
upper teeth are then set so that they occlude well with the lower teeth. Then the buccal contours are built on the upper teeth in wax which is later replaced by tooth-colored acrylic resin to fulfill esthetic requirements and to provide support for the cheek9 (Fig. 5, A). (b) Another method can be used alternatively for the same problem. The upper posterior teeth are arranged first to meet the requirements of esthetics. The lower teeth are kept on the crest of the ridge. This will result in an unfavorable occlusal relationship of the upper and lower posterior teeth. In order to establish a functional occlusal contact between the upper and lower posterior teeth, wax is added on the palatal aspect of the upper posterior teeth. This wax is later replaced by toothcolored acrylic resin. This gives a functionally effective occlusal contact as well as an esthetically acceptable buccal surface contour of the upper posterior teeth4 (Fig. 5, B). Nonanatomic posterior teeth are best for these procedures as they allow more latitude in their buccolingual placement. SUMMARY
The upper-lower ridge relationship is an individual problem for each complete denture patient. When it is normal, not much effort is needed to obtain a suitable arrangement of artificial teeth. However, when these relations are abnormal, one has to deviate from the usual procedures to achieve successful results. One aspect of the problem of abnormal ridge relations was discussed (i.e., maxillary protrusion and wider maxillary arch and its management during arrangement of artificial teeth). The two conditions are dealt with separately for the sake of clarity and better understanding of the problem. References 1. 2. 3. 4.
Nichols, I. G.: Prosthetic Dentistry, St. Louis, 1930, The C. Fenn, H. R. B., Liddelow, K. P., and Gimson, A. P.: ed. 2, London, 1961, Staples Press, p.259. Craddock, F. W.: Prosthetic Dentistry. A Clinical Outline, Kimpton, p. 186. Hardy, I. R., and Passamonti, G.: A Method of Arranging Jaw Relations, J. PROSTHET. DENT. 13: 606-610, 1963. GOVERNMENT NEW CIVIL AHMEDABAD GU JARAT,
DENTAL HOSPITAL
380016 INDIA
COLLEGE COMPOUND
V. Mosby Company, p. 337. Clinical Dental Prosthetics, ed.
3, London,
Artificial
Teeth
1956, for
Henry Class
II