Clinical applications of concepts of functional anatomy and speech science to complete denture prosthodontics

Clinical applications of concepts of functional anatomy and speech science to complete denture prosthodontics

THE PHENOMENON COMPLETE DENTURE CLINICAL APPLICATIONS AND SPEECH SCIENCE Part VIII. The I FUNCTION IN PROSTHODONTZCS OF CONCEPTS OF FUNCTIONAL A...

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THE PHENOMENON COMPLETE DENTURE

CLINICAL APPLICATIONS AND SPEECH SCIENCE Part

VIII.

The

I

FUNCTION IN PROSTHODONTZCS

OF CONCEPTS OF FUNCTIONAL ANATOMY TO COMPLETE DENTURE PROSTIIODONTICS

Phases

of Denture

Construction*

L. MARTONE, D.D.S.,M.Sc.**

ALEXANDER Norfolk,

Final

OF

Va.

DENTURE CONSTRUCTION, we cannot say that the recording phases end at a particular point and the esthetic phase begins. Teeth must be positioned before the final maxillomandibular relation records can be made, and certainly the vertical relationships which are established become of extreme importance esthetically in matters relating to the length of the face. Thus, each is a part of what might be called the interpretive phase in which the dentist, utilizing all of the information he has gained in previous procedures, finalizes his concept of dentures which will meet the functional and esthetic needs of the patient. This is the phase which challenges both his scientific knowledge and his artistic ingenuity. It is this creative effort which will be considered in this final article of the series. N COMPLETE

SELECTION

OF TEETH

Teeth must be selected before they can be positioned. That fact is the only precedence selection has over positioning. Many aids have been suggested to assist the dentist in tooth selection.l These are valuable but not infallible. Even when they have been employed, it must be recognized that the selection remains a provisional one until it has been proved functionally and esthetically satisfactory. This proof does not come until the teeth have been properly positioned and checked in the patient’s mouth during functional activities. Unless we have the courage to correct at that stage a faulty tooth selection, we are very likely to end up with outstanding dentures that do not fit in with the appearance of the patient. *Part I, J. PROS DEN. 11:1009-1018, 1961; Part II, J. PROS. DEN. 12:4-27, 1962; Part III, J. PROS. DEN. 12:206-219, 1962; Part IV, J. PROS. DEN. 12:409-419, 1962; Part V, J. PROS. DEN. 12:629-636, 1962; Part VI, J. PROS. DEN. 12:817-834, 1962; Part VII, J. PROS. DEN. 13:4-33, 1963. **Associate, Departments of Prosthodontics and Anatomy, Medical College of Virginia. 204

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OF FUNCTION

IN

COMPLETE

DENTURE

PROSTHODONTICS

20.5

Although certain esthetic factors may be considered with the face in a static state, final esthetic determinations should never be made with the face in repose. The vital movements associated with speech and facial expressions are actually esthetics in action.2 Dentures must serve in harmony with such functions. Therefore, the mouth in action must be the testing environment (Fig. 1). This functional testing of tooth selection does not preclude the necessary considerations which must be given to the shade, size, and form of teeth. It is rather a means of verification of these when the selected teeth have been positioned and observed as to their effectiveness as a harmonious counterpart of the facial and body entity. Denture patients who are first seen while they have their natural teeth which can serve as aids in selection of artificial teeth, or edentulous patients who have available records of their natural teeth or previous dentures which attempted to restore the size, shape, and color of the natural teeth, ordinarily pose less of a problem in the matter of tooth selection. However, old dentures can be an effective guide only when we evaluate them critically. Perpetuating previous errors, even when the patient requests that we do so, will not improve the quality of the den-

A.

B.

Fig.

1.-A,

Static

esthetics

in a functioning

mouth.

B, Esthetics

in action.

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MARTONE

March-April,

Den. 1963

ture service we are giving the patient. If the old dentures serve only to confuse but not to enlighten us, they should be ignored. For the edentulous patient who has no records whatsoever, we must make our esthetic determinations from the oral remnants in light of our understanding of natural structures. ANATOMIC

GUIDES

Size and Forwa of the Anterior Teeth.-The size of natural teeth is proportionally related to the size of the body, the face, and the dental arch. The general shape of the facial frame, its width, and its length are governing factors in determining the size and contours of the teeth to be selected. The width of the face is determined by measuring the distance between the zygomatic arches, The length of the face may be determined by measuring the distance from the superior furrow of the forehead to the lower border of the chin. A provisional average for the width and length of the maxillary central incisor may be arrived at by dividing the width and the length of the face by 16.l The cast of the patient’s mouth provides information as to the arch shape which will serve as a guide in selecting the form of the tooth. Because the cast reflects the shrinkage which has occurred, measurements should be made on the occlusion rim which compensates for this shrinkage. The occlusion rims should be scored at the corners of the mouth. The distance between these scorings is approximately one third of the distance between the zygomatic arches. With this information, the maxillary anterior teeth and the suggested complement of mandibular teeth are selected from the mold guide. Posterior Teeth.-Posterior teeth are also selected on a provisional basis since they may have to be changed in accordance with the development of the occlusal scheme. Thirty-three degree anatomic teeth are selected in a length which is determined by the length of the anterior teeth, the interarch space, and the size of the ridges. The mesiodistal width is determined by the distance from the mandibular cuspid to the anterior part of the retromolar pad. In general, the occlusal surfaces of artificial teeth should be smaller than those of the natural teeth. Shade.-Two basic principles may serve as initial guides in determining the color of the t,eeth. The tooth shade should be in harmony with, not in contrast to, the over-all complexion, e. g., the lighter the skin tone, the lighter the tooth. This blending of shades is frequently evident in biologic harmonies. The second.principle relates to the age of the patient. In general, the darker shades of teeth are more harmonious for older patients, and the lighter shades are more congruous for the young who have had less discoloration from staining and restorations, and less loss of translucency from natural wear. AN

APPROACH

TO ESTHETICS

Complete dentures are when the teeth and aIveoIar tonicity of musculature, and such loss is a drastic aging

: THE

TOTAL

HARMONY

OF THE

FACE

an attempt to offset the losses which have processes are gone and resultant losses of elasticity of skin have become apparent. The change for the lower part of the face. An

occurred function, effect of esthetic

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FUNCTION

IN

COMPLETE

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2.-A,

The

effects

207

B.

A. Fig.

PROSTHODONTICS

of structural

losses.

B, An

attempt

to

restore

these

losses.

restoration should attempt to bring the appearance of the lower part of the face into a harmonious relationship with the upper part (Fig. 2). If we lose sight of this objective, we are in danger of creating a composition based on false harmonies. In so doing, we merely substitute one glaring discord for another. Esthetic objectives should be based on the realization that the total harmony of the face is the harmonious relationship of each of its parts. Natural beauty, while involving basic symmetry, also involves asymmetry within this symmetry, and thus monotony is avoided by infinite variations. By employing this artifice of Nature, we can minimize the artificiality of the denture appearance. PROVISIONAL

POSITIONING

OF

TEETH

With the functionally contoured occlusion rims as guides, the 12 anterior teeth are set with their labial surfaces flush with those of the occlusion rims to provide support for the lips. The arrangement of the natural teeth is followed whenever a record of it is available. For preliminary verification records, the posterior teeth are set in centric occlusion. In this preliminary setup, I prefer to position the 12 anterior teeth rather than relegate the responsibility to a dental laboratory technician. There are several reasons for this : (1) I know the physiologic and esthetic requirements of the patient. (2) In setting the teeth, I may recognize a need to modify the provisional tooth selection. (3) On some occasions, the time I have spent in contouring occlusion rims to approximate the denture shape has been wasted because the contours

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Den. 1963

were not completely respected by the person setting the teeth. (4) I have found that several times my judgment was influenced by a preliminary tooth arrangement made by a dental laboratory technician. It is difficult to excuse errors which occur as a result of this. (5) A dental laboratory technician can do a better job in setting posterior teeth when he has the anterior tooth arrangement as a guide. VERIFICATION

PROCEDURES

With the trial denture bases in place, the patient is instructed to count from 1 to 10. This provides the first opportunity to observe critically the relationship of the teeth to the features of the patient. Frequently, our first observations are the best guides to determine whether the relationship is a harmonious one or whether the composition requires major or minor changes. A major error of judgment in the selection of teeth must be corrected at this time. One way to avoid postinsertion problems which result from the use of the wrong teeth is to prevent the problems from occurring. LIP

SUPPORT

In this first observation of the patient with the trial dentures in place, one of our immediate reactions will be to the amount of support which has been provided for the lips. Adequate lip support involves more than a concern for esthetics. Physiologically, the functions of speech, facial expression, eating, and breathing are all affected by it. The main objectives in establishing adequate lip support are to obtain and maintain the natural harmonies of the lips and cheeks during the complex interplay of the musculature in functional performances. In order to accomplish these objectives, the teeth must be placed in the positions which the natural teeth occupied. In doing this, the primary object of a functional, esthetic composition is attained, that is, the proper positioning of the teeth. The positioning and arrangement of the anterior teeth not only determine the support for the lips but also serve as an incisal guidance which is used as an anterior anatomic landmark in developing the occlusion. The framework of musculature chiefly responsible for the contours and movements of the lips is the orbicularis oris which is composed of the interlacing fibers of all of the muscles of the lips. Because of its complexity, Sicher3 has described the orbicularis oris as a muscle which “is only functionally but not anatomically a unit.” In order to apply the principle of muscular efficiency (i.e., for a muscle to function properly, the integrity of its functional length must be maintained), it becomes imperative that this functioning unit be held in the natural position it occupied during its development when it was supported by the natural teeth and supporting structures. Closely associated with the problems of support for the orbicularis oris muscle are those that relate to the modioli which also must be positioned properly if natural lip movements are to occur. In considering problems of lip support, more attention is generally accorded to the maxillary lip than to the mandibular lip. Pursing and sphincter actions of the lips and the symmetrical outlines of their muscle fibers may suggest that the

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OF FUNCTION

IN COMPLETE

DENTURE

PROSTHODONTICS

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two lips function in a similar fashion. The elevating action produced in the mandibular lip by the mentalis muscle is one evidence that this is not so. The mandibular lip, bounded laterally by the labiomarginal sulci, the rima oris above, and the mentolabial sulcus below, is usually smaller and more active than the maxillary lip.3 The relative sizes, shapes, and surface outlines of the two lips change during functional movements (Fig. 3 ) . Problems of support for the mandibular lip must include the action of the mentalis muscle which reduces the space available for the denture flange in the vestibule. In most mouths where a minimal amount of resorption has occurred, the mentolabial sulcus is slightly inferior to the reflective tissues of the labial vestibule. Because of this, overfilling of the labial vestibule with the denture flange

Fig. 3.-Natural lip contours. The maxillary lip is bounded laterally by the nasolabial sulci, above by the nose, below by the rima oris. The mandibular lip is bounded laterally by the labiomarginal sulci, above by the rima oris, and below by the mentolabial sulcus.

will not obliterate the mentolabial sulcus but rather will distort the upper region of the lip by plumping out an area where loss has not occurred (Fig. 4). The correct support is provided where structural loss exists by proper positioning of the labial surfaces of the mandibular anterior teeth. In instances where a marked resorption of the residual ridge has occurred, resulting in a lowering of the reflective tissues of the labial vestibule to a level with or below the mentdabial sulcus, the sulcus can be eradicated by overfilling the vestibular region with the denture flange. This is not advisable from the standpoint of esthetics or function. When the patient is observed in movements of speech or expression, the effects of the amount of lip support on the underlying musculature and the structures controlled by it become apparent (Fig. 5). Observations can best be made by the dentist standing in front of the patient and then at a 45 degree angle to the right of the patient. GUIDES

FOR DEVELOPING

ADEQUATE

LIP

SUPPORT

The following guides may be used in establishing adequate lip support: 1. The best aids will be found in the information revealed in study and photographs of the natural teeth.

casts

I. Pros. Den. March-April. 1963

210

B.

c.

Fig.

4.

A.

B.

Fig.

5.

Fig. 4.-A, A profile view of the lips naturally supported. B, A profile view showing excessive support. Note that the mentolabial sulcus is not eradicated by this plumping effect, but that the entire mandibular lip is distorted. C, A frontal view showing excessive support of the lip. Note the evidences of strain and tenseness around the mouth region. Fig. 5.-A, Lip support for a patient 60 years of age. Note the natural contours of the lips and the support of the modiolus which is provided by the positioning of the teeth. B, Natural lip support is evidenced in a ZO-year-old patient with a complete natural dentition. The mandibular lip during smiling serves as a template for the in&al edges of the maxillary teeth. Note the comparatively short maxillary lip characteristic of youth.

V”‘ume

Number

I3

2

PHEKOMENOK

OF FUNCTIOS

IN

COMPLETE

Fig.

6.

Fig.

7.

DENTURE

PROSTAODCi’iTICS

211

Fig. B.-The correlation of the arch form of the foundational support with that of the teeth. The general ovoid-tapering outlines conform with the facial contour. A, The maxillary CaSt and the mandibular cast with the metal base. B, The maxillary and mandibular dentures. Fig. 7.-A sagittal section through the midline of the maxillary cast illustrating: (1) The relationship of the maxillary central incisor to the midline with the incisive papila as a guide; (2) the distance between the labial surface of the maxillary central incisor and the center of the incisive papilla, and (3) the long axis of the imaginary root of the maxillary central incisor projected in relation to a badly resorbed ridge.

2. The same dimensions and contours of the functional occlusion rims should be maintained by the anterior teeth to preserve static and dynamic facial length. 3. The arch form of the teeth should follow the arch form of the residual ridge (Fig 6). 4. The labial surfaces of the teeth should be 8 to 10 mm. in front of the incisive papilla and should be out as far or in front of the labial flange (Fig. 7). 5. The midline of the teeth is usually in the same sagittal plane as the incisive papilla and the midline of the face (Fig. 7).

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MARTONE

Fig. 8.-A, The patient saying “six.” In sibilant sounds the interocclusal space is reduced. If the teeth contact while he is saying “six,” the vertical dimension of occlusion should be reduced to increase the interocclusal distance. B, The patient saying “judge.” In saying this word, the mandible moves forward, bringing the mandibular incisors into a near end-to-end contact with the maxillary incisors.

Fig. 9.-The patient saying “five.” The distortion teeth were too long which is verified by the imbedding lip as the sound is made.

of the f to a 2) sound of the maxillary teeth

indicated that the in the mandibular

6. The distance from the necks of the anterior teeth to the residual ridge is governed by the amount of resorption of the ridge (Fig. 7). 7. The incisal edges of the maxillary and mandibular teeth should approach each other, but not contact, during the pronunciation of words containing the sibilants S, z, zCt, ch, and j (Fig. 8). 8. The length of the maxillary anterior teeth .and the amount which shows below the lip should be checked by having the patient say words beginning with f and o. If the f sounds like V, the teeth are too long (Fig. 9). 9. If th, as in these and those, sounds like d, the teeth are positioned too far palatally (Fig. 10). 10. The teeth should be positioned until there is no space between teeth and lips during normal lip movements in performing these phonetic functions (Fig. 11).

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PHONETIC

PHENOMENON

OF FUNCTION

IN COMPLETE

DENTURE

2 13

PROSTIIODONTlCS

EVALUATIONS

Phonetic determinations have a dual significance in the verification of prosthodontic records. They provide both auditory and visual aids which may be used by the dentist in his evaluations. His judgments are, therefore, based on his abilities to analyze the sound of sounds and the sight of sounds and to interpret one in relation to the other. During the tryin stage, two limitations must be recognized in all phonetic evaluations : (1) the trial bases have not been refined to the proportions of the finished denture, and (2) no period of adaptability has been available. Speech performances

Fig. 10.--A, the patient saying “these.” B, The the correct positions for these linguodental sounds.

patient

Fig. Il.-The teeth and lips in harmonious relationship that there is no space between the teeth and the lips and lips has been restored @xing function.

saying

that

during the

“those.”

phonetic anatomic

The

teeth

function. integrity

are

in

Note of the

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Den. 1963

at this stage, then, will be those which are unrehearsed insofar as they are produced in a new environment which lacks ultimate refinements. Consequently, visual observations are quite likely to be more significant than auditory evaluations. The patient is instructed to count rapidly from 45 to 70. In saying these sounds, the edges of the maxillary teeth should lightly contact the mandibular lip. When the repeated sibilant sounds are made (60 to 69), specific observations should be made to see if the maxillary and mandibular teeth contact each other. If such contacts occur, they indicate insufficient interocclusal clearance and a need to decrease vertical length of the trial dentures. Additional speech sounds may be utilized for phonetic testings. The ability of the dentist to evaluate phonetic performances is increased by his studies of the speech of patients with natural, normal dentitions (Fig. 12). Unfortunately, the specialist in complete denture prosthodontics has limited opportunities for such observations of the patients he regularly treats. SURFACE

ANATOMY

INDICATIONS

OF THE

AMOUNT

OF LIP

SUPPORT

External evidences which assist in critically evaluating the amount of lip support provided by the denture bases and the teeth may be studied with the face in repose. The corners and the vermilion borders of the lips, the philtrum, the mentolabial, nasolabial, and labiomarginal sulci are surface markings which must be considered. However, the length of time that structural support has been missing and the subsequent loss of tissue tone from atrophy must also be recognized in evaluating efforts to provide lip support. Indications of insufficient support include : a perpetuation of the general appearance of collapse around the mouth region; a reduction of the size of the vermilion borders of the lips ; a drooping of the corners of the mouth ; a deepening of the sulci ; and an obliteration of the philtrum. Indications of too much support include: tensed, stretched appearance of the lips which can result in tension lines around the mouth ; distortion of the philtrum ; obliterations of the sulci ; and an eradication of the natural contours of the lower part of the face that serve to correlate that portion with the upper part of the face. This correlation is the constant toward which our esthetic efforts must be directed. VERIFICATION

OF MAXILLOMANDIBULAR

RELATION

RECORDS

In previous procedures maxillomandibular relations were recorded provi: sionally. These provisional records now serve as a means for obtaining more accurate records after the teeth have been positioned. Vertical Relations.-During the recording phases, records of the vertical dimension of rest position and the vertical dimension of occlusion were established provisionally, utilizing information obtained from diagnostic casts, natural teeth, old dentures, from observations of functional performances of swallowing and speaking, and from studies of facial landmarks. The same methods which were used to determine the vertical relations originally are employed to verify the records. The face is observed in repose and in function. The amount of support is evaluated in relation to evidences of collapse or of stretched, strained areas. Lip contours and the approximation of the lips in phonetic performances are checked.

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PHENOMENON

OF FUNCTION

IN

COMPLETE

DENTURE

PROSTHODONTICS

2 1.5

Clinical observations are made of the amount of tongue space which has been provided. These observations are made with the mouth half opened and the tongue in a resting position. If the tongue has been crowded, there is likely to be a space

Fig. 12-A series of illustrations of a patient with natural teeth saying “Mississippi.” A, The m sound which approximates physiologic rest position. B, the beginning of the first s sound. C, The Analization of the first s sound. D, The finalization of the second s sound with the mandible moving forward slightly, positioning itself in order that the lips may come together for the pent-up pressures to produce the plosive p. E, The plosive p sound. F, The final vowel i sound.

216

MARTONE

between the teeth and the cheeks in the posterior region, or the teeth and the lips in the anterior region, or both. The tongue will appear crowded, humped, and retruded, and there will be apparent difficulty in swallowing. If the vertical dimension of occlusion is decreased, there will be inadequate tongue space. This condition will cause frequent “strained” swallowing and a frequent return to the vertical dimension of rest position. If strained swallowing movements are noted, clinical verification of the interocclusal distance may be made by having the patient say “sixty-six.” More than likely there will be evidence of too much interocclusal distance. If the teeth are placed on the ridge for leverage purposes, the shape of the palate will change. This change will result in a narrower vault and make it difficult for the tongue to reach the palate. To compensate for this and to restore the same palatal shape, the palatal thickness must be increased, thus lessening the space available for the tongue. It should be noted that the quality of phonetic performance decreases proportionately with the increase of the thickness of the palate. Centric Relation.--Centric relation has been defined4 as “the most posterior relation of the mandible to the maxillae at the established vertical dimension.” It is a position frequently assumed to bring the teeth together in functions of eating and swallowing. It is a bone-to-bone relation which serves as an accurate starting position from which may be developed any desired occlusal scheme. Because it is the only maxillomandibular relation which may accurately be repeated, it serves as a reference relation for other maxillomandibular relations which must be determined within a clinically acceptable range that is governed by the dentist’s ability to obtain and interpret these records. Regardless of the method used to make the centric relation record, the accuracy of the record must be verified because dentures will inevitably fail unless the occlusal scheme is in harmony with this relation.5 Clinically, the accuracy of centric relation is tested by placing the trial dentures in the mouth and having the patient move the mandible into centric relation until the posterior teeth contact. Observations are made to see if the posterior teeth slide on each other after the very first contact is made. If a slide of porcelain on porcelain is detected, the centric relation record is not correct, and a new interocclusal record must be made in order to remount the lower cast. The method of obtaining centric relation records, which will be described, has the advantage of being comparatively simple to perform and to verify. Its simplicity, however, does not rule out the necessity for applying clinical discipline in the use of the materials which are to be employed. The Recording of Centric Relation.-In order to record unstrained maxillomandibular relations, I use a modified plaster* as an interocclusal medium because the material does not offer resistance to closure, and it retains its rigid form for relating the casts to each other on the articulator and verifying this relationship. During the making of the provisional maxillomandibular registrations, the patient has been rehearsed in the desired closure until we have both learned to recognize the centric position. The patient is comfortably seated in an upright position in the dental chair. The trial dentures are placed in the mouth, and plaster, which *Plastogum,

Harry

J. Bosworth

Company.

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OF

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IN

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has the consistency of heavy cream, is placed with a cement spatula over the occlusal surfaces of the posterior teeth. If desired, the setting time may be reduced b) decreasing the water content and increasing the rapidity and duration of the me.chanical spatulation of the plaster. The recording bases are stabilized in the mouth with the thumb and fore-finger of the left hand which is held in an inverted position. The patient is in,struced to “pull the lower jaw back and close gently.” (The word “bite” is never used in instructions to the patient for this record.) At the same time the righ;: index fingernail is placed on top of the mandibular anterior teeth to help hold the base down and to indicate to me the direction in which the jaw is moving, which should be to its unstrained, retruded horizontal position of centric relation at the established vertical dimension. The finger should not be used as a guide to direcl: the jaw in this movement, for this will result in a strained and forced maxilloM mandibular relationship because of the natural tendency of the neuromusculature to resist such pressure. The closure is stopped just before the teeth make contact with each other (just short of the position of vertical dimension of occlusion). Care must be taken to make sure the relationship of the anterior teeth remains the same, otherwise the remounting record cannot be used. After the plaster has set, it is removed and examined to see that there has been no contact of the cusps. The slightest cusp contact of teeth through the plaster has a tendency to elicit within the patient an inhibitory neuromuscular response which will result in a compensatory mandibular movement toward an eccentric posi-tion. Any evidence of cusp contact indicates an inaccurate record and a need to repeat the procedure. The trial bases are placed on the mounted casts. The incisal guide pin on the articulator is lowered approximately to the thickness of the interocclusal record. The maxillary denture is closed into the indentations of the plaster interocclusal record which has been related to the mandibular denture. If the teeth do not coincide with the indentations in the recording plaster, the record is incorrect. The procedures are repeated until the records made in the patient’s mouth are identical with those on the articulator. If this cannot be accomplished, the mandibular cast is remounted by means of another interocclusal record, and the procedure is repeated until the records are interchangeable. In order to maintain the established vertical dimension of occlusion and allow the anterior teeth to return to their original overlap, all of the interfering posterior teeth are removed and reset intc centric occlusion. When the teeth fit into the indentations perfectly in all directions, the mounting is accepted as being in centric relation. Protrusive Relation Record.-The protrusive relation record is governed by the paths of the condyles in the patient and the position of the anterior teeth. The posterior factor of the record is the condylar path, which becomes an unalterable horizontal inclination of the condylar guidance on the articulator. The anterior factor is the incisal guidance provided by the anterior teeth which have been positioned to meet functional esthetic requirements. The horizontal overlap of the incisor teeth determines the distance the mandible is protruded when the protrusive record is made.

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The protrusive relation record is obtained after the esthetic requirements of positioning the anterior teeth have been met. The protrusive record is made in plaster. The plaster is applied to the occlusal surfaces of the mandibular posterior teeth and the incisal surfaces of the mandibular cuspids. It is not applied to the incisal surfaces of the mandibular central and lateral incisors so that observations can be made of the relationships of these teeth and the amount of indentations of the posterior and cuspid teeth into the plaster.interocclusal record. The patient is instructed to “bite” on the front teeth. This action brings the incisor teeth into an end-to-end position. This record is used to adjust the condylar guidances of the articulator. These guidances are set at inclinations which correspond to the condylar path inclinations of the patient. The inclinations of the condylar guidances are only equivalent to the condylar path inclinations, and will vary in degree with the location of the casts vertically within the articulator. ESTHETIC

REFINEMENTS

Even though the anterior teeth have been positioned to meet functional and general esthetic requirements, there are numerous possibilities of esthetic refinements which may be accomplished while the patient is still in the chair. Such refinements should in no way alter the basic positioning of the teeth which was made to meet functional requirements, nor should they change records which have been verified. The purpose of these refinements is to attempt to incorporate in the dentures some of the subtle variations employed by Nature. Here again, photographs or diagnostic casts of the patient’s natural teeth will furnish the best guides (Fig. 13). A slight rotation or tilt of a tooth, an overlapping of teeth, a diastema, an irregularity of arrangement, or a variation of colors of the teeth can contribute to the natural appearance of the dentures. Labial surfaces of the teeth that are parallel to the profile, incisal edges of maxillary teeth that follow the smiling line of the mandibular lip, incisal and proximal surfaces of teeth which have been ground to simulate natural wear, and teeth which simulate restorations that were in natural teeth are additional refinement possibilities. Observations should be made of the amount of tooth structure and the amount of denture base material that is exposed during various oral functions. Esthetic contouring and tinting of the denture bases is important when these will be visible during speech and facial expressions. 8-8 Studies of natural dentitions and tissues can improve our efforts in this ‘direction (Fig. 14). Esthetic refinements are based on the requirements of the individual patient. Successful interpretation of esthetic refinements is dependent upon the artistic concepts and skills of the dentist. EVALUATING

ESTHETICS

It is the dentist’s responsibility to develop and perfect an esthetic composition in accord with the possibilities and limitations of the individual patient. When, and o&y when, the dentist feels that he has accomplished this, the patient is asked to

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Fig. 13.-Two views of the same patient. No diagnostic casts were available for this patient. Her old dentures and a photograph showing her natural teeth were the only guides for esthetics. A, A portrait study, made of the patient at the age of 35, showing her natural teeth. Note the maxillary right lateral incisor has all of the characteristics of an artificial tooth. The patient said this replacement had not corresponded to her natural tooth. She described the tooth and asked that her new denture reflect that similarity. B, A photograph made during the patient’s first visit, showing the dentures which had been made 12 years previously. Note the general appearance of artificiality caused .by: (1) a poor selection of stock teeth; (2) the typical arrangement of the anterior incisors with the teeth set on the crest of the ridge; (3) the dominance of the m’axillary cuspids in relation to both position and length, and (4) the plane of occlusion which is too low.

Fig. structures.

14.-An

intraoral

view

of a patient

showing

the

natural

dentition

and

its supporting

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Den. 1963

observe and evaluate the results. The dentist is then in a position to use a positive approach in discussing with the patient what has been done and why it has been done. Patients are more likely to seek to direct the esthetic interpretation if they sense an uncertainty or indecision in the attitude of the dentist. It is desirable for both the patient and the dentist to think in terms of a functional, not a static, evaluation of esthetics. This is done by having the patient, after he has become accustomed to the feel of the dentures in his mouth, leave the dental chair, walk about the office, and then begin speaking. He-is asked to stand at a conversational distance in front of a three-way wall mirror and to count slowly from 45 to 70 and to carry on a normal conversation while the dentist and the patient observe the performance in the mirror. Then the patient is asked to turn and walk toward the dentist and to continue talking. The patient is thus conditioned to begin thinking of his total appearance with dentures rather than the appearance of the dentures as a separate entity. In attempting to develop this type of critical evaluation in the patient, I avoid the use of a small hand mirror which tends to encourage unnatural grimacing efforts on the part of the patient. Additional esthetic refinements which may be suggested by the patient are considered and incorporated when advisable. The esthetic results are important to both the patient and the dentist, and neither should be rushed into approving a composition until there is a real basis for such approval. POSITIONING

OF THE

POSTERIOR

TEETH

AND

PERFECTION

OF THE

OCCLUSAL

SCHEME

Thus far, the posterior teeth have been provisionally positioned in centric occlusion, and an occlusal level has been established as an aid in verifying maxillomandibular relation records. A verification of the height of the occlusal plane is made by checking it with the height of the incisal edges of the mandibular cuspids and the posterior third of the retromolar pads. The orientation of the occlusal plane should be modified slightly so that it is parallel to the foundation plane of the supporting ridge. The problem now is to place the teeth buccolingually in the position the position is where the tongue natural teeth occupied. This physiologic “neutral” and cheeks exert equal pressures on the lingual and buccal surfaces of the teeth. To accomplish this, and at the same time respect leverage, the mandibular teeth are positioned by using the following two guides. The buccal cusps of the mandibular first molars are placed directly over the crest of the ridge, and the lingual cusps of the posterior teeth should lie directly under a line extending from the mesial of the cuspids to the buccal side of the retromolar pads. The line should curve the same as the lower ridge. If the ridges incline upward toward the retromolar pads, smaller posterior teeth are used or one or more of them are omitted to avoid placing teeth on these inclines. This will prevent the mandibular denture from skidding forward when occlusal forces are applied. The maxillary teeth are set into balanced occlusion with the mandibular teeth.Qs10 Occasionally, longer posterior teeth are used or the maxillary first premolars are replaced with cuspids to avoid a marked contrast in size (length)

;;;,re;

‘2”

PHENOMENON

OF

FUNCTION

between the anterior and posterior in the maxillary buccal regions. THE

I’OLISHEL)

IN

COMPLETE

DENTURE

teeth and the exposure

PROSTHODONTICS

221

of tlellture 1)ase nlatcria.!

SURFACES

All three surfaces of the dentures, i.e., the impression, the occlusal, and the: polished surfaces, should fit the tissues or the parts of the opposing denture which they contact.ll The development of the impressions and the positioning of the teeth constitute two thirds of this requirement. The anatomic contouring and finishing of the polished surfaces make up the remaining one third. Areawise, the polished surfaces nearly equal the impression and occlusal surfaces of dentures for the average edentulous mouth. The areas of the polished surfaces usually become larger in proportion to the amount of resorption of the alveolar ridges. Unfortunately, the contouring oi these surfaces is frequently relegated to the dental laboratory technician. Contouring of the polished surfaces in accordance with the functional anatomy which will be contacting these surfaces will not only improve the dentures from the standpoints of esthetics, phonetics, and comfort, but will also add to the retention and stability of the dentures.8 A study of healthy dental arches of patients with natural teeth, and observations of the contours and surface markings of diagnostic casts aid in developing and incorporating natural contours in dentures (Fig. 15). When these polished surfaces are placed in the dentures, they become a series of inclined planes which, if properly used, add to the retention and stability of dentures, since these surfaces are contoured to fit the movable musculature of the cheeks, lips, and tongue when they are changing shape and gliding over these surfaces. l’he Mandibular Denture.-The mandibular denture is generally more difficult than the maxillary for the dentist to construct and for the patient to master. There are several reasons for this : (1) The mandibular denture is seated on a movable bone. (2) The available foundational area for the mandibular denture is about one third of that for the maxillary denture. (3) The perimeters of the borders of the mand~~~~lardenture are about twice as long as those of the maxillary denture. (4) The actlvlty of the tongue, cheeks, and lips has more direct influences upon the mandibular rather than the maxillary denture. By properly designing the inclined planes of the denture flanges, and by not placing the lingual surfaces of the teeth lingual to the flanges, the lips, cheeks, and tongue can serve to keep the denture in place rather than to dislodge it by resting on or gliding over the “shelves” of these inclined planes. The buccal surfaces of the buccal flanges should face outward and upward. The flanges in the buccal vestibules should extend out over the buccal shelves and under the buccinator muscles in the cheeks. The labial flanges are determined by the position of the mandibular incisors which must be in the same place the natural teeth occupied. The contours of these flanges and the teeth must give support to the lip during function. The labial surfaces of the flanges should not be anterior to the labial surfaces of the teeth.

222

MARTONE

Fig. 15.-Diagnostic casts of the mouth an opportunity for the study of natural oral

of the patient structures.

ivarck.A’~~:

shown

in Fig.

14. Such

casts

%=&

provide

Between the labial and buccal flanges, the flange in the buccal notch region should be narrow to allow for movements of elevating the corners of the mouth. The lingual surfaces of the lingual flange should face inward and upward so that the borders lie under the tongue. Thus the border seal can be maintained during function, and air cannot get under the denture. The Maxillary Denture.-The buccal surfaces should face outward and downward and should fill the buccal vestibules. The buccal flanges in the buccal notch regions should be sufficiently narrow to allow for the freedom of movements of the modioli and their muscle components. The labial surfaces should not be anterior to the labial surfaces of the teeth. The palatal surface should face inward and downward and simulate the natural anatomic contours. For better speech performance and adaptability, the thickness of the palate should be uniform and as thin as practical for the type of denture base material used. However, as the palate slopes toward the alveolar ridges, the thickness will vary according to the amount of resorption. COMPLETION

OF THE

DENTURES

After the dentures have been cured, and before they can be given to the patient, there are necessary finishing and perfecting procedures which must be

;;;;“;

‘2” PHENOMENON

OF FUNCTION

IN COMPLETE

DENTURE

PROSTHODONTICS

22.3

performed. The impatience of the patient to receive the dentures should not be allowed to interfere with the accomplishment of the completion requirements. Time spent at this phase of construction in order to perfect the denture bases and the occlusion will save time during the postinsertion period, and will contribute to the comfort and success of the dentures. The maxillary denture is not removed from the cast after the denture is cured until the denture has been related to the articulator and an occlusal index record has been made on a remounting jig. This index serves as a face-bow and data. record (Fig. 16), and may be made by the technician. The casts are cut into sections and carefully removed from the dentures. Dur-. ing the finishing and polishing of the dentures, care is taken to preserve the anatomic contours of the denture bases intact. The dentures are placed in the patient’s mouth, and cotton rolls are placed on the occlusal surfaces of the teeth and held in place by a biting force. This is done to prevent the existing malocclusion from affecting the neuromuscular system or the tissues supporting the dentures. Unless this precaution is taken, the interocclusal centric and protrusive relation records, which are to be made, may be inaccurate. The patient is not dismissed with the new dentures until the occlusion is perfected by remounting the dentures on the articulator by means of new interocclusal protrusive and centric relation plaster records. In order to attain the desired cuspal forms for the occlusal scheme, the occlusion is perfected by selective grinding. lo Occlusal disharmonies are analyzed while the dentures are securely mounted on the articulator upon which they were fabricated. This is done by interposing thin articulating paper between the teeth so that markings may be obtained by tapping and sliding the teeth together. The analysis is made for each of the horizontal positions, centric, right and left lateral, and protrusive occlusions. The corrections are made by a series of grinding procedures for each position analyzed. However, the established vertical dimension of occlusion must be maintained. Consideration is given the function of that part of the tooth in all other positions as well as the position which is being corrected.

A.

B.

Fig. l&-Two views of an occlusal index record. A, The occlusal index record which serves as a permanent face-bow record. B, The reverse side of the occlusal index record which provides a permanent record of important data.

224

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J. Pros. March-April,

Den. 1963

An assortment of small mounted stones is used to grind the offending portions of each tooth. In refining the occlusion in centric position, a locked occlusion is avoided by widening the central fossae of the posterior teeth. This is accomplished by placing the condylar balls in the slots in the condylar guidances of the articulator from 0.5 to 1.0 mm. posterior from the centric relation position.12 The central fossae of the posterior teeth are ground so that there is a slight freedom of intercuspation without involving the inclined planes of the cusps within a limited range of mandibular movements. The lateral occlusal refinements are accomplished by selective grinding of only one lateral occlusal direction at a time. The inclines of the teeth, not the cusps, are ground according to the BULL (Buccal of the Upper, Lingual of the Lower) formula. Then the other side is perfected in the same manner. The protrusive occlusion is perfected by eliminating the cuspal interferences which are apparent when the mandibular member of the articulator is moved forward. The lingual incisal edges of the maxillary anterior teeth and the labial incisal edges of the mandibular anterior teeth are ground until balancing contacts are made with the mesiolingual cusps of the maxillary second molars and the distalmarginal ridges of the mandibular second molars. Selective grinding to perfect occlusion actually becomes the basis for additional esthetic refinements which are made at this time, such as the grinding of the incisal edges of the anterior teeth to simulate the natural wear which would have been evident in the patient’s natural teeth. l3 Then the dentures are cleaned and polished in preparation for insertion in the patient’s mouth. EDUCATING

THE

PATIENT

TO COMPLETE

DENTURES

Effective education of the patient begins at the initial interview and continues throughout his treatment. l4 The patient normally evidences curiosity as various procedures are being performed. In answering such questions, the dentist can lay the foundation for educating the patient as to his responsibilities for the success of this mutual undertaking. During the treatment program, I attempt to keep the patient informed as to what I am doing, why I am doing it, and how it will affect the successful use of the dentures. This preconditioning of the patient eliminates the need for a mass of instructions at the time the new dentures are inserted in the mouth. During the time when the patient’s mouth was being brought into a healthy condition, the patient learned the value of rest for the tissues. Consequently, he knows why it is advisable to leave dentures out at night. In one of the initial appointments, he is introduced to the book New Teeth for Old,i5 and during the treatment, he is encouraged to discuss the material he has read. Throughout the construction phases, the patient knows that I have been observing and using his speech as a functional guide in making the dentures, and that I have been studying his facial expressions in relation to the dentures. He is thus conditioned to think of the dentures in relation to several functions rather than as only a part of the masticatory mechanism. Consequently, he knows that he faces problems in mastering the dentures in relation to all of these func-

V”‘u’ne Number

l3 2

PHENOMENON

OF

FUNCTIOX

IN

COMPLETE

DENTURE

I’ROSTHODONTICS

225

tions. If he says that he is planning to have a steak the day he receives his new dentures, he is told why it is inadvisable to return immediately to a complete menu as far as foods which are difficult to masticate are concerned. He has been told about parts of the denture that were designed so that his tongue could assist in holding the denture in place instead of dislodging it. When the dentures are inserted, he is asked to explore these areas with his tongue and then to begin adapting his tongue movements to take advantage of them. Patient education is adapted to fit the needs of the individual patient and his previous dental history. It is offered, whenever possible,at the time the patient asks a question. It is presented in a method that will stimulate him to recognize his responsibilities. Instructions at the time of insertion of the dentures are primarily for the purposes of re-emphasizing any points which have not been sufficiently clarified previously. The patient is reminded that adjustments will be required, and the appointments are arranged at the time the dentures are placed in his mouth. THE

POSTINSERTION

PHASE

The postinsertion period is one of the most critical phases is prosthodontic treatment. It is the time when the patient begins to assume his responsibilities for the successof the program, and the dentist begins to evaluate the results of his previous efforts. During this period, the dentist is called upon to use not only his technical skills, but all of the knowledge he has gained about the patient in the past in order to lead him into a successful denture-wearing experience. It is possible for successful dentures to be “denture failures” simply because the necessary adjustments are not made. Appointments for these adjustments should be routinely scheduled in the first few days following the insertion of the dentures. These appointments enable the dentist to (1) make the dentures comfortable for the patient, (2) make sure the patient is wearing the dentures, (3) observe the rate at which the patient is adapting to the dentures, and (4) analyze the sore areas and the patient’s complaints in relation to further adjustments which may be required.ler17 Prior to the construction of the dentures, efforts were made to get the mouth of the patient into a healthy condition. The dentist has a further responsibility and that is to Izee$ the mouth in a healthy condition. To do this, I place all my denture patients on a regular recall list in order to check periodically the occlusion of the dentures and the condition of the underlying tissues. I have seldom found a patient who has not benefited by being recalled 3 to 6 months after the dentures were inserted to have them remounted and the occlusion adjusted. This is a necessary part of a prosthodontic service because,in the first few days following the insertion of the dentures, there is no way to predict exactly what will occur when the dentures have been used under functional stressesof the muscular forces. The individual patient’s needs will determine the basis for future recall appointments. By maintaining occlusal harmony, frequent relining of the dentures may be

226

Fig. 17.-A prosthodontic interpretation is based upon the concepts suggested in this

J. Pros. March-April,

MARTONE

for the patient series.

shown

in Fig.

13. This

interpretation

avoided. One of the greatest satisfactions in the practice of prosthodontics occurs when the dentist examines a patient who has been wearing dentures for a number of years and finds comparatively little loss of supporting structures and the tissues in a normal, healthy condition .ls The patient, however, must be educated as to the importance of preserving this foundational support. When he understands this, he is more likely to seek this service and realize the justification of a fee for it. SUMMARY

The final phases of denture construction are effectively accomplished insofar as they are developed in harmony with the functioning anatomy of which the dentures are to become a part. Maxillomandibular relations which were provisionally recorded must be verified and corrected after the teeth have been positioned. Speech plays an important role in this verification, in esthetic determinations, and in the critical evaluation of the completed dentures. The muscles responsible for facial expressions in the regions of the lips and checks must be properly supported by the dentures so that natural movements of facial expression can take place. Dentures constructed in accordance with principles of occlusal harmonies must be maintained in these same harmonies to retain the anatomic foundational support. CONCLUSIONS

In the study of the phenomenon of function in complete denture prosthodontics, concepts of the sciences of anatomy and speech have been clinically applied to the construction of complete dentures. The polyfunctional nature of the oral cavity places stringent requirements on oral prostheses in relation to the activities of facial expression, speaking, breathing, and eating. If complete dentures are to fulfill the functional and esthetic needs of the patient, they must be constructed on the basis of dynamic, not static concepts (Fig. 17). These concepts include : 1. A progressive diagnosis based on the evaluation of the total entity of the patient.

;$‘$

‘2” PHENOMENON

OF FUNCTION

IN

COMPLETE

DENTURE

227

PROSTHODONTICS

2. The preparation of the edentulous mouth to get it in a healthy condition prior to the construction of dentures. 3. Preliminary impression procedures, utilizing regional functional anatomy to produce accurate functional trays in which accurate final impressions can be developed. 4. The development of all three (the impression, occlusal, and polished) surfaces of the dentures in conformity with the tissues or opposing denture surfaces to provide increased retention and stability. 5. The provisional recording of maxillomandibular relations by using physiologic activities and by developing trial dentures that resemble the finished dentures which will be used in the verification of these records. h. The utilization of remaining oral structures, diagnostic casts, and photo-, graphs as guides in positioning the teeth where the natural teeth were, to determine the esthetic and phonetic considerations in relation to the vitality factor of the patient. 7. The use of natural concepts of symmetry and asymmetry in esthetic efforts designed to bring the lower part of the face in harmony with the upper part. 8. The continual maintenance of occlusal harmonies in an effort to preserve the oral foundation and prevent or minimize changes. 9. A realistic education of the patient as to his responsibilities in the use of his dentures and in the maintenance of their foundational support. 10. A recognition of the need for the education of the dental profession to accept its responsibilities in an effort to improve the quality of prosthodontic services for patients. REFERENCES 1. House, 2. 3. 4. 5. 6. 7.

M. M., and Loop, J. L.: Form and Color Harmony in the Dental Art, Monograph, Whittier, Calif., 1939, M. M. House. Martone, A. L. : Anatomy of Facial Expression and Its Prosthodontic Significance, J. PROS. DEN. 12:1020-1042, 1962. Sicher, H. : Oral Anatomy, St. Louis, 1952, The C. V. Mosby Company. Boucher, C. 0.: The Current Status of Prosthodontics, J. PROS. DEN. 10:411-425, 1960. Trapozzano, V. R.: Occlusion in Relation to Prosthodontics, D. Clin. N. America, pp. 313325, 1957. Hardy, I. R.: Problem-Solving in Denture Esthetics, D. Clin. N. America, pp. 305-320, 1960. Pound, E.: Applying Harmony in Selecting and Arranging Teeth, D. Clin. N. America, pp. 241-258, 1962. Pound,E.: Esthetic Denturesand Their Phonetic Values, J. PROS. DEN. 1:98-111, 1951.

8. 9. Boucher,C. 0.: Occlusionin Prosthodontics, J. PROS. DEN. 3:633-6X, lo.

Boucher,

C. 0.:

Dental

Prosthetic

Laboratory

MosbyCompany,pp.68-88. E. W. : Principles of Full Denture

11. 12.

Fish, Schuyler,

13.

Nagle,

14.

Perry,

Manual,

1953.

ed. 2, St. Louis,

1950,

The

C. V.

Construction, ed. 5, London, 1952, Staples Press. C. H.: An Evaluation of Incisal Guidance and Its Influence in Restorative Dentistry, J. PROS. DEN. 9:374-378, 1959. R. J.. and Sears, V. H.: Dental Prosthetics; Complete Dentures, St. Louis, 1958, The C. V. Mosby Company, p. 374. C.: Examination, Diagnosis, and Treatment Planning, J. PROS. DEN. 10:1004-1010,

1960.

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15. Sears, V. H.: New Teeth for Old, ed. 2, St. Louis, 1952, The C. V. Mosby Company. 16. Kingery, R. H.: The Postinsertion Phase of Denture Treatment, D. Clin. N. America, pp. 343-358, 1960. 17. Hickey, J. C., Boucher, C. O., and Woelfel, J. B.: Responsibility of the Dentist in Complete Dentures, J. PROS. DEN. 12:637-653, 1962. 18. DeVan, M. M.: An Analysis of Stress Counteraction on the Part of Alveolar Bone, With a View to Its Preservation, D. Cosmos 77:109, 1935. 909

NORFOLK

NORFOLK

MEDICAL

7, VA.

TOWER