ANTERIOR TOOTH SELECTION

The selection of teeth for complete dentures is best understood if the anterior teeth are

considered separately from the posterior teeth. The anterior teeth are primarily selected to satisfy

esthetic requirements, whereas the posterior teeth are primarily selected to satisfy masticatory

requirements.

Both the anterior and posterior teeth must function in harmony with and be anatomically and

physiologically compatible with the surrounding oral environment. Technically, the anterior

teeth are composed of the six maxillary and six mandibular teeth; however, there are occasions

when the maxillary premolars particularly the first, must be considered more for esthetics than

for masticatory function.

ESTHETICS

1. Pertaining to the study of beauty and the sense of beautiful. Descriptive of a specific creation

that results from such study; objectifies beauty and attractiveness, and elicits pleasure

2. The branch of philosophy dealing with beauty.

3. In dentistry, the theory and philosophy that deal with beauty and the beautiful, especially with

respect to the appearance of a dental restoration, as achieved through its form and/or color.

Those subjective and objective elements and principles underlying the beauty and attractiveness

of an object, design or principle.

Dental Esthetics the application of the principles of esthetics to the natural or artificial teeth and

restorations

Denture Esthetics the effect produced by a dental prosthesis that affects the beauty and

attractiveness of the person.

(GPT-7, J PROSTHET DENT, 81(1): 39-110; 1999)

Denture esthetics is defined as “the cosmetic effect produced by a dental prosthesis which affects

the desirable beauty, attractiveness, character, and dignity of the individual”. Proper placement

of teeth should be functional as well as esthetically pleasing.

It provides details so that an object becomes appealing to the onlooker and pleases them.

Beautiful face always provides a good background for smile. Pleasing smiles are related to the

visual attention of teeth. When a person smiles, if too much attention is attracted by the teeth it is

bad. Very white teeth on a dark skinned individual have this defect. If insufficient attention is

drawn by the teeth, then the person will appear edentulous. The optimum nature of attention is

very difficult to define but a dentist can train his eyes by looking at normal faces and derive his

own optimum perception.

Historical Evolution of Esthetics in Dentistry:

Historically, esthetics synonymous with denture esthetics.

1930's - Sears -Art Factors in full denture construction

1950's - Frush and Fisher -"dentogenic" denture -

1970's - Lombardi- Visual perception in dentures

Vig - Kinetics of Anterior Tooth Display

Pound - Vertical dimension

Levin - Golden proportion

1980's - Mavroskovfis and Ritchie - Face form for selection of maxillary centrals

Lorton - mandibular anteriors

Scandrett- width of maxillary anteriors

Tjan and Miller - Esthetic factors in a smile

Rieder - Provisionals and Esthetics in Fixed prosthodontics

1990's - Guichet - Function to esthetics

Rosenberg and Cutler - Periodontal considerations

Turbyfill - Esthetic Removable prosthetics

Today, esthetics includes not only complete dentures, a wide variety of fixed prosthodontics,

veneers, implants, as well as bleaching. 4,470 internet web sites "cosmetic dentistry”, 3,667

Medline articles on cosmetic dentistry.

The subject of esthetics should be examined from three points of view. These are the biological

—physiological, the biomechanical, and the psychological (or self-image) viewpoint.

BIOLOGICAL PHYSIOLOGICAL

It is necessary to have an understanding of facial musculature, normal facial appearance and the

physiological limits, or parameters, within which esthetic compromises are to be made.

A proper impression procedure is necessary to provide dentist with a final maxillary cast that has

accurate representation of the labial vestibule and all of the other remaining structures.

The dentist should also have a visual concept of the cause-and-effect relationship.

For example, as patients become older, there are natural lines of the face that tend to deepen and

to appear accentuated. Since the majority of edentulous patients are found within the older age

group, it is wise to remember that there is a loss of elasticity of the facial musculature. There is a

tendency to want to “plump out” the face with additional thickness of denture base material. This

is usually counterproductive unless the musculature is almost totally flaccid. Otherwise, the

musculature tends to act to loosen the denture, or the facial appearance becomes strained.

Another approach to removing facial wrinkles is to increase the vertical dimension. This ap-

proach is fraught with the greatest of dangers and must be used with caution. It is true that the

facial appearance will be better, but the ability to function, patient comfort, and the long-range

health of the residual alveolar ridges will frequently be adversely affected. It may also cause a

“clicking sound” during speech. The lower anteriors should be placed lower in order to maintain

an adequate interarch space. This will usually also necessitate a lowering of the occlusal plane

posteriorly. This will have the effect of placing the teeth closer to the mandibular ridge, which

should aid in lending stability to the mandibular denture. (It is necessary to keep in mind that if

one lowers the occlusal plane too much, it is possible to create a problem of biting the tongue.)

The maxillary teeth should be moved slightly more anteriorly at the incisal edges so that there

will be sufficient clearance in protrusive. (It may be necessary to bevel the incisal edges of the

mandibular anteriors in an incisolingual to labial—gingival direction, and to bevel the incisal

edges of the maxillary anteriors.) Tilting the incisal edges of the mandibular incisors lingually

should be avoided. According to Muyskems, “for every 1 mm the incisal edges of the

mandibular anterior teeth are posterior to their normal arrangement, the tongue is deprived of

approximately 100 cubic mm of space in which to function.

BIOMECHANICAL

There are certain mechanical limitations in the placement of anterior teeth that must be taken into

account. A primary question about placement that is always asked is “on the ridge?” or “how far

off the ridge?”

A general answer is that you should place the anterior teeth as closely in relation to the residual

ridge as were the original natural teeth.

In fact, Fish states, “In the upper jaw there is no exception to the rule of replacing the natural

teeth by setting the artificial ones in exactly the same relation to the body of the maxillae unless

the patient’s appearance will be improved by some slight modification.

However, Fish also says, “The proper position for the teeth is not necessarily on the ridge, inside

the ridge, or outside the ridge, but at a point where the tongue and cheek pressures balance.

Beresin and Schiesser state:

With the neutral zone concept, tooth position and flange contours are determined by the com-

pound occlusion rims that result from functional muscle action. The neutral zone developed by

each individual patient is usually not a narrow restricted area and therefore permits some latitude

for positioning of the anterior teeth to obtain adequate lip support for optimum facial appearance.

This is especially true with the upper neutral zone, since it is not nearly as critical for denture

stability as is the lower neutral zone.

PSYCHOLOGICAL

Esthetics concerns itself with more than just oral or facial appearance. The patient’s self-image is

also an important factor. A patient’s perception of his or her appearance may result in a broad

smile (if it is a positive self-evaluation) or a tight-lipped, small, controlled smile. In the latter

case, the patient’s own doubts and dissatisfaction about his or her appearance result in the patient

conveying these feelings to others. A patient with a poor self-image may appear dour, unsure,

hesitant, questioning, reticent, and introverted. A patient with a more positive feeling tends to

smile more broadly. The smile is important because it is really the frame that enhances the

picture, the picture being the dentures.

Golden proportion: It is a mathematical relationship between 0.618, 1, and 1.618 such that the

ratio of the smaller to the larger is equivalent to the ratio of the larger to the whole.

Everything that is pleasing to the human eye is in golden proportion.

A proportion between the teeth and smile spaces between the corner of mouth and the dental arch

form a “backdrop” for the anterior segment, and is in golden proportion to the width of the smile.

ANTERIOR TOOTH SELECTION

There are many methods of choosing anterior teeth for the edentulous patient. Anterior tooth

selection is a tentative step, which can be verified only by the dentist utilizing the trial base, and

confirmed by the patient and family or friends.

It is appropriate at the first visit to make tentative decisions as to shape, shade, position, and

mold of teeth to be used. If the patient had a previous set of dentures, the easiest and most

sensible approach is to converse with the patient. Observe what changes you would like to

achieve, and then ask the patient leading questions.

While the patient is answering your questions, observe the following areas to see if they can be

improved upon:

1. Do the corners of the mouth turn down; is the philtrum lacking; does it appear as if the patient

has no teeth?

2. Are the teeth too big or too small for the face, too obvious, too straight across; is there a

concave incisal line?

3. Does the patient “hiss” or “click” in speaking; do the teeth appear to touch during speech?

Patients should be asked and guided, at the initial and subsequent visits, to express frankly their

opinions of their old dentures and their perceptions of their own appearance.

Shade

Color is the sensation resulting from stimulation of the retina of the eye by light waves of certain

lengths.

Shade is the degree of darkness of a color with reference to its mixture with black. According to

Clark the shade itself has got three dimensions

Hue- the basic color of the spectrum.

Value- the brightness or reflectance

Chroma- the intensity of the hue.

When a tooth is viewed for the purpose of determining its color, two principal colors—yellow

and gray—are evident. The yellow is more prominent in the gingival third, and the gray is more

prominent in the incisal third.

Hue of the tooth is actually the quality that the dentist attempts to duplicate. One other slight

modification appears in teeth with thin incisal edges. The yellow disappears, and the edge

appears blue-gray. This is the only place that blue appears in the tooth.

From anterior to posterior, the value shifts to darker side

Females have comparatively lighter shade

Shade is first suggested by the dentist but mainly selected by the patient who will definitely opt

for a lighter shade

Contrasting shade should not be selected because it will make the teeth more conspicuous

As age advances, the value shifts towards darker side

Shade guide-Vita 3 D master provides an appropriate distribution of shades according to the

age. Groups 1and 2 for youngsters, 3 for middle aged and 4 and 5 for older individuals

Old dentures and natural teeth can act as a guide in the selection of shade

The position of the patient and the source of light are very important in color selection. The

patient should be in an upright position. The dentist should be in a position so that the teeth are

viewed in a plane perpendicular to the dentist’s plane of vision. The teeth should be observed

from different angles to make certain that the shadows do not influence the color. The patient’s

mouth should not be opened too wide but should remain a dark cavity as in ordinary conditions.

White light is considered suitable.

Eyes fatigue to color perception very rapidly, and for this reason they should not be focused on a

tooth more than a few seconds. If the proper shade (lightness or darkness) is hard to establish, the

tooth and the shade guide should be viewed from a distance of 6 or 8 feet.

Krajicek states, “It is not so important what shade is selected but that a variety of shades of teeth

be selected to be used within a single six-tooth composition”. From a practical standpoint, if the

patient desires extremely light teeth and states that nothing else is acceptable, then it is prudent to

ask that another family member or friend be invited to be present when the final decision is

made. If the patient is adamant in the desire for teeth, which in your opinion are much too light

or dark, there are but two solutions: either acquiesce to the patient’s desires, or do not treat the

patient.

It is helpful to give the patient two or three choices in choosing a shade. After ascertaining the

patient’s preference—for example, old teeth were too light or dark, or “too artificial looking”—

give the patient an opportunity to express an opinion about two or three shades that you have

selected.

The use of a single tooth from a shade guide is not very reliable when selecting the shade;

however, if the teeth are allowed to remain in the guide holder held to one side of the nose of the

patient, the tooth that is in harmony will be recognized.

A study by Hallarman showed that there is apparently little correlation between either natural

hair or eye color and tooth color. There is also little correlation between skin color of the

forehead or cheek and the patient’s own anterior teeth. So, these entities can also be used in the

selection of the shade.

Size of anterior teeth:

To select the size of the anteriors; patient’s pre extraction records can be used as such as:

Patient’s diagnostic casts with natural or restored teeth.

Most recent photographs prior to the extractions. Facial photographs are more helpful for the

dentist in determining the placement of anterior teeth, arch form and lip support. Measurements

can be made from the radiographs of the teeth. Six anatomic entities are used as guides to select

anterior teeth for size.

1. Size of the face: Anthropometrics measurements of 555 skulls revealed that greatest

bizygomatic width divided by 16 gives the approximate width of the upper central incisor. So the

average width of the maxillary central incisor is estimated to be one sixteenth of the width of the

face measured between zygoma.

Length is the measure of one sixteenth of the distance from the hairline to the lower edge of the

bone of the chin with the face at rest.

Again if the bizygomatic width is divided by 3.3 it will approximately give the width of the six

anterior teeth arranged on the curve of the properly contoured occlusal rim.

Bizygomatic width can be measured with the face bow.

The ratio of the cranial circumference to the width of the upper anteriors has been shown to be

10:1.

The general guide that is according to the tooth selection chart, the overall width of the upper

anterior teeth if it is less than 48mm then the teeth are relatively small, if it is more than 52mm

then the teeth are relatively large.

2. Incisal papilla and the canine eminences or the buccal frenum: If the canine eminences are

discernible, a line can be placed on the cast at the distal termination of the eminence.

If the eminences are not discernible, the attachments of the buccal frenum can be used. A line

placed slightly anterior to the frenum attachment will be distal to the eminence. Measure the dis-

tance from the distal of one canine eminence to the distal of the other with a flexible ruler. The

ruler should follow the contour of the ridge, and as it reaches the midline, it should be placed on

the anterior border of the incisal papilla because the maxillary central incisors are situated

labially to the papilla. The combined width of the six maxillary anterior teeth is determined in

millimeters.

Another method to locate the distal of the canine eminences is to use the maxillary occlusion

rim. After the occlusion rim has been properly contoured and the vertical length of the anterior

section has been established, the rim is placed to position in the mouth. The patient is requested

to relax with the lips touching. A pointed instrument used as a marker is passed to the occlusion

rim at each corner of the lips, and a mark is recorded. The marker is passed on a line parallel to

the pupils of the eyes. The distance between the marks following the contour of the arch

measured in millimeters is the combined width of the six maxillary anterior teeth.

3. Maxillomandibular relations: Any disproportion in size between the maxillary and the

mandibular arches influences the length, the width, and the position of the teeth. The sizes and

the positions of the teeth will have to vary from the accepted normal if the teeth in one arch are

to complement the teeth in the other arch.

In instances of protruded mandibles, the mandibular anterior teeth are frequently larger than

normal. If the mandibles are retruded, the mandibular anterior teeth are frequently smaller. In

protrusion, the face is usually longer, and longer faces frequently require longer teeth. Accurately

articulated casts with the jaws in centric relation are necessary for the satisfactory determination

of maxillomandibular relations, since patients can shift the mandible and compensate for some of

the malrelations.

4. The contour of the residual ridges:

The artificial teeth should be placed to follow the contour of the residual ridges that existed

when the natural teeth were present. The loss of contour as result of resorption, accident, or

surgery makes this a difficult task. Knowledge of the direction of resorption of the two arches

will allow a fairly accurate visualization of the original contour. Resorption of the maxillae in the

anterior segment of the arch is in a vertical and palatal direction.

Posteriorly, the resorption is in a vertical and medial direction.

The resorption of the mandible in the anterior segment of the arch is in a vertical and lingual

direction; posteriorly, the resorption is in a vertical and slightly lingual direction, however, as

resorption occurs, because of the morphology, the maxillary arch appears smaller and the

mandibular arch larger.

A square arch with the eminences present will be ovoid or tapering in their absence.

5. The vertical distance between the ridges:

The length of the teeth is determined by the available space between the existing ridges. When

the space is available, it is more esthetically acceptable to use a tooth long enough to eliminate

the display of the denture base. Teeth are more attractive in appearance than denture base

materials, even those denture bases fabricated to simulate the oral mucosa; Denture bases that

simulate the oral mucosa are referred to as characterized, personalized or natural appearing.

Teeth that are not in harmony in length and breadth are not natural appearing, but there will be

times when the characterized denture bases will be more acceptable than disharmony in length

and breadth.

6. The lips:

When the lips are relaxed and apart, the labial surfaces of the maxillary anterior teeth support

the upper lip. Frequently, the incisal edge extends inferior to or slightly below the lip margin.

This extension will vary in relation to the fullness of the lip.

When the teeth are in occlusion and the lips are together, the labial incisal third of the maxillary

anterior teeth supports the superior border of the lower lip. This support can be demonstrated by

pressing against the lower lip when the teeth are in occlusion. In speech the incisal edges of the

maxillary anterior teeth contact the lower lip at the junction of the moist and dry surfaces of the

vermilion border. This is best demonstrated when the letter F, as in ‘‘fifty-five’’ is pronounced.

The properly contoured maxillary occlusion rim will include this position as the incisal edge

position and will aid in determining the length of the teeth.

Form of anterior teeth:

Three factors are used as guides in the selection of anterior teeth for form.

1. The form and contour of the face:

Artificial teeth will not present a pleasing appearance if they draw attention away from the

surrounding environment. The form of a tooth should conform to the contour of the face as con-

sidered from the labial, mesial, distal, and incisal aspects. The general outline of the tooth should

conform to the general outline of the face when viewed from the frontal aspect. A tooth viewed

from the mesial or distal should conform to the contour of the profile.

House and loop classified according to the form. Their classification was based not only on the

facial outline form of a tooth but also on the mesio-distal and gingivoincisal contours as well.

They proposed three pure forms i.e. square, tapering, ovoid and combinations. House held that

good esthetics could be achieved only if the face, arches and tooth shapes all were in harmony

2. Sex: Curved facial features are associated with feminity, and square features are associated

with masculinity. Since there is harmony between tooth form and environment it follows that the

teeth of females are more ovoid or tapering then square. However, some males have female fea-

tures and some females have male features, and the form of the teeth will vary as these features

vary.

3. Age: As the features change with the aging processes, so does the form of the teeth. The lips

lose their curves and Cupid’s bow, and the teeth wear at the incisal edges and interproximal

surfaces. The labial surfaces seem flatter, and the outline form appears squarer. As the body of

the female loses its curves, the teeth lose their curves. The teeth of the male become squarer in

form to complement added weight and square ness of body.

Materials used:

Today one may readily obtain either porcelain or the plastic anteriors. The choice depends on the

personal preference.

Porcelain teeth are easily set if there is sufficient intermaxillary space.

Porcelain teeth:

Advantages:

Because the investment material does not stick to them dentures made with the porcelain teeth

are easier to deflask and polished.

They are color stable over the long periods.

Disadvantages:

Their mechanical retention prevents the close adaptation to the ridge.

Extremely difficult to stain and can rarely if ever be made to duplicate exactly the form and the

color of specific natural tooth, as one would wish making an immediate denture.

Acrylic teeth:

Advantages:

Versatile. They do not depend on the mechanical retention. Chemical bonding occurs.

They are easily altered, stained and are prepared to accept metal or other restorative materials

whenever desirable.

Ideal for the immediate denture.

From the esthetic point of view the acrylic teeth have the greater potential than the porcelain

teeth.

Disadvantages:

Tend to loose their identities during processing.

Difficult to polish after deflasking.

Anteroposterior positioning of anterior teeth is extremely important in esthetics and phonetics

because of the support that teeth give to lips, cheeks, and other issues of the oral cavity. Since it

is necessary to maintain proper support of these tissues for natural esthetes, it is important to

place artificial teeth in essentially he same position as natural teeth. This consideration must not

be overlooked when using a resorbed residual maxillary ridge as the primary control for tooth

position.

Extreme changes in shape and/or size make a resorbed ridge a questionable landmark to use as a

positive control for tooth position. Setting artificial teeth directly over the center of (resorbed)

residual ridges has been quite common; however, this practice makes the development of natural

esthetics practically impossible or, at best, extremely difficult because the natural teeth seldom

occupy the so-called over-the-ridge position.

No dental restoration, particularly a complete denture, can be truly esthetic or functional if it fails

to position teeth in their proper natural place in the mouth. Properly positioned teeth give support

to the lips, cheeks, and other tissues of the oral cavity that is vital to a natural appearance.

After the removal of teeth, the loss of bone structure is usually greater on the buccolabial aspect

of the maxillary ridge than on the palatal aspect. As a result, the center of the residual ridge is

more palatal and therefore somewhat smaller and different in shape than it was prior to removal

of the teeth.

If artificial teeth are to have the best and/or most natural esthetic and functional qualities, it is

essential to place them in a position as close as possible to that occupied by the natural teeth,

providing these were acceptable esthetically and functionally.

One of the most common errors in tooth positioning, setting the teeth over the ridge without

consideration of the original positioning of the natural teeth, is superimposed over the original

position of the natural central incisor. The loss of vertical dimension and lip support, as well as

the inevitable resultant loss in esthetics, is readily apparent. For natural esthetics and phonetics,

the artificial teeth should be of the same length and in the same position anteroposteriorly as the

original natural teeth. An artificial tooth set on the ridge may deviate considerably from its true

natural position. This "on-the-ridge" position of the teeth cannot afford the lip the proper support.

In determining the forward position of the maxillary central incisor, a useful guide is the

relationship in natural dentitions between the upper central and the incisive papilla, after

outlining the papilla in pencil and bisecting it, the procedure is to measure the distance from the

center of the papilla to the labial surface of the tooth. The average distances for the three basic

arch forms, square, ovoid, and tapering, differ they are 5,6, 7 mm respectively. Although these

distances may vary, the averages serve as reasonable guides and starting points when finding out

how far forward to set a central incisor.

Relationship of arch form to tooth arrangement

Nature tends to harmonize not only the form of the maxillary central incisors with the form of

the face; but also with the form of the arch and arrangement of the teeth. Persons with

predominantly square faces often have mainly square arrangements of teeth. In general, these

same principles of harmony apply to the square tapering, tapering, and ovoid types.

Although loss of teeth and consequent resorption of the labial and buccal alveolar processes can

change the original form of the maxillary arch, nature leaves a guide to tooth arrangement in the

form of the mandibular arch. Even though resorption can and does occur, usually the direction is

downward, primarily toward the body of the mandible, and often the lower arch tends to preserve

its outline form. Frequently, the mandibular ridge is a fairly reliable guide to tooth arrangement

for the edentulous patient.

Tooth arrangement in square arch

Usually the arrangement is to set the two central incisors to almost a straight line across the front

of the square arch. Then the lateral incisors are placed with a nearly full labial aspect so that they

show little rotation in at the distal aspect. This positioning of the central and lateral incisors gives

width to the positioning of the canines and prominence to these teeth. The four incisors tend to

have little rotation, and the radius of the square arch tends to be wider than that of the tapering

arch.

The larger radius of this arch allows sufficient room for placing the incisors without crowding or

lapping. Overall, in the typal square arrangement the visual effect is fairly straight from canine to

canine. In addition, teeth arranged in a typal square-arch configuration tend to be more or less

straight up and down, rather than sloping. The full or nearly full labial surface presented by the

six anterior teeth gives a broad effect that is in harmony with the broad square face.

Tooth arrangement in tapering arch

In the tapering arch, the central incisors are often farther forward of the canines than in other

types of arches. A characteristic of the tapering arrangement is the rotation of the central incisors

on their long axes inward at the distal aspect. This rotation more or less sets the two teeth at an

angle, thereby creating a pointed effect to the arrangement. In the tapering arch, considerable

rotating and lapping of teeth are often evident because this arch has less space than any other

type, and crowding is inevitable. Crowding and rotation of the teeth reduce the amount of labial

surface visible anteriorly. The typal tapering arrangement does not look as wide as other set ups.

Usually this narrowing is in harmony with the narrowing effect visible in the lower third of the

tapering face.

Other typical characteristics of arrangements of this type are the raising of the lateral incisors

from the occlusal plane and the depressing of them at the gingival plane. In addition, the necks of

the canines at the gingival area are usually quite prominent and the incisal tips of the canines are

often at the same height or slightly above the incisal edges of the lateral incisors. In a typal

tapering arrangement, the teeth exhibit some slope; for example, one may project the incisal

edges of the central and lateral incisors forward and bring out the cervical area of the canines,

leaving their incisal tips in harmony with the central and lateral incisors.

Tooth arrangement in square tapering arch

The square tapering arrangement combines characteristics of the square and the tapering forms,

but modifies both. It has characteristic square placement of the central incisors, such as little or

no rotation, with the typical tapering effect or rotation of the lateral incisors and canines.

However, the square tapering arrangement does not exhibit the illusion of fullness or width like

the square arrangement; the canines often show more distal rotation than in a square

arrangement.

Tooth arrangement in ovoid arch

The ovoid arrangement has a definite curvature. The central incisors in the ovoid anterior arch

usually set well forward of the canines. They are usually in a position between that of the square

arch and that of the tapering arch. In the ovoid arrangement, there is seldom rotation. As a result,

a typical alignment shows fullness of the labial surface from canine to canine. This alignment

and the setting to the curved arch give a broad, rounding effect that harmonizes with a round

ovoid face.

Considerations Affecting Placement and Positioning Of Anterior Teeth

In placing and positioning the maxillary anterior teeth, the objective is to provide a balance

between maximum esthetics and proper phonetics. As seen previously, anterior teeth set directly

over the ridges are not in the position formerly occupied by the natural teeth. Therefore these

anterior teeth fail to provide support for the musculature of the lower third of the face, and they

interfere with proper phonetics. Without the proper support, these facial muscles tend to sag into

unnatural positions. In positioning the maxillary anteriors, their relationship to the occlusal and

sagittal planes is important.

Occlusal plane

Generally the central incisor, when set at approximately the same angle as the natural tooth, is at

an inclination slightly offset from the vertical edge, and the incisal edge touches the occlusal

plane. The lateral incisor often has a slightly more accentuated slope than that of the central

incisor. The incisal edge of the lateral incisor may be raised slightly, approximately 0.5 mm from

the occlusal plane. The canine usually sets more prominently and to a line at right angles to the

occlusal plane, with the incisal edge set on that plane.

Sagittal plane

The sagittal plane divides the body vertically into halves. In the dental arch, this plane

approximates the median line. The desirable angulation to the sagittal plane or median line can

be correlated to the form of both the arch and the tooth. Generally, the square arch form and

tooth, as well as the ovoid arch form and tooth, can be set to approximately the same angulations.

The tapering forms desirably should be set to a slightly greater angulation.

It is essential to realize that any technique for the preliminary arrangement of teeth, both

anteriors and posteriors, is based on average, or so-called normal, conditions. Many times

practical considerations dictate modifications of these methods to cope most effectively with the

multitude of individual differences in the oral and facial anatomy. However, basic principles that

apply to average situations will serve as a workable foundation on which to base necessary

modifications. After placement of the six maxillary anterior teeth in position with due regard to

the requirements of vertical dimension, vertical overlap, and horizontal overlap, the remaining

considerations that affect their arrangement in the arch are essentially esthetic.

Factors of Softness and Vigor

Some conditions directly affect the individual arrangement and esthetic appearance of a natural

dentition. Softness in tooth arrangement depends on the selection of harmonious forms of teeth

as a prerequisite and the use of smaller lateral and central incisors wherever indicated. With

respect to tooth arrangement and selection, softness can also mean a reduction of the labial

surface in terms of its visual appearance.

A rounded mesiodistal curvature of the tooth in combination with an ovoid outline of the tooth

appears softer than a flat mesiodistal tooth with more angularity in its outline. A rounded form or

a curved form is much softer to the eye than a straight line or a Hat plane.

On the other hand, a characteristic of the bold, vigorous face is the dominant .size and alignment

of the teeth. The relatively larger size of the lateral incisor and canines and their straight bold

arrangement are important considerations in achieving the effect o strength. However, vigor,

boldness, and strength are not necessarily solely or primarily masculine characteristics because

many female patients also have strong bold faces.

Softening, or the alternate, vigor, depends on the size and shape of teeth in relationship to the

face, as well as the positioning of the teeth in the arch. Tilt more labial surface of the teeth that is

visible, particularly in the lateral incisors, the stronger the tooth arrangement appears.

Positioning the two central incisors normally makes the front view of these teeth look normal in

size or in relation to each other. Positioning the two central incisors with the mesial edges

slightly more prominent and with the distal edges rotated inwardly makes them appear smaller.

From a straight front view, the teeth in the latter arrangement look smaller than those in the first

one. This illusion results from merely rotating the teeth to give them a somewhat smaller and

softer look. Rounding the distoincisal surface of each tooth slightly with a rubber wheel softens

this effect still more. It is essential to avoid rounding all teeth exactly alike to maintain a slight

degree of asymmetry in this arrangement,

In a third arrangement, placing the same two central incisors to make the teeth look larger creates

the illusion of boldness or strength. This effect is the result of merely rotating the mesial edges in

and the distal edges out to show more facial surface. Also, depressing the lateral incisors slightly

behind the central incisors accentuates the boldness and strength of the tooth arrangement more.

Grinding the teeth incisally, thereby leaving the distoincisal area prominent, and grinding toward

the mesioincisal area make tins illusion even stronger.

Influence of Asymmetry on Tooth Arrangement

Another point of interest in tooth arrangement is the relationship between facial asymmetry and

the associated asymmetry in tooth arrangement. Few faces have true symmetry in terms of a

precise left- and right-side balance. Many faces that appear to be symmetrical on initial

observation display a variety of subtle or minute differences on closer observation.

Similarly, subtle and minute differences exist in the arrangement of natural teeth. Conversely,

asymmetry may be apparent to a marked degree in many faces; the left and right sides may show

considerable variance. In instances when asymmetry in the face is pronounced, asymmetry may

also be seen in the tooth arrangement.

Asymmetry determines the relative vigor or softness of either side of the face. The size and

position of the anterior and posterior teeth in the arrangement produce the asymmetry. It is an

extremely subtle factor, and as minor a variation as the depression and/or rotation of either the

left or right canine at the gingival surface is sufficient to create this effect. At times also the

lateral incisors may differ slightly in size, such as a reduction in the size of a lateral incisor on

one side of the mouth to make it smaller than the corresponding one on the opposite side.

Perhaps even positioning one central incisor slightly anterior to the other may produce the same

effect.

Spacing of Anterior Teeth

When developing more characterization in a denture, spacing the teeth is another important

consideration, but one that requires caution. Although spacing of teeth may be one of the many

irregularities in nature, it is less noticeable in a natural dentition than generally believed.

Dentitions with a noticeable degree of spacing between the maxillary central incisors occur

rather in- frequently, and spacing between two or more teeth in the maxillary arch appears only

slightly more frequently.

Overall spacing usually results from drifting of the teeth. In addition, patients with an abnormally

large arch in which the size of the teeth is in proportion to the size of the face also show spacing

because the teeth are too small to fill the arch properly. Preoperative records, such as casts or

photographs, are excellent guides to natural spacing between central incisors or to overall

spacing, rather than arbitrary rules.

It is possible to introduce esthetic spacing into a denture. The inverted type of spacing may be

difficult for the patient to keep clean. A straight up-and-down vertical space between the two

central incisors can also be given. A conical type space; the space is larger at the incisal opening

than toward the gingival opening. To be classified as a true diastema, the space should be

completely open, and the adjacent teeth should make no contact. As noted previously,

preoperative records are a preferred guide to spacing.

Modification of an embrasure produces another type of relationship. Here the teeth are in

contact, in contrast to the diastema in which the abutting teeth make no contact. The amount of

space present after setting up the teeth to make normal contact in the incisal third area. Slight

grinding of the teeth and modification with a rubber wheel will enlarge the embrasures and move

the contact toward the middle third of the teeth.

Natural dentitions that have a pleasing appearance often may have slight spacing, diastema,

between the lateral incisors and canines. This effect may be incorporated judiciously in a denture

tooth arrangement to improve the appearance of the patient.

Crowding and Lapping

Crowding or lapping of the teeth in a natural dentition often is present in abnormally small

arches. The size of the teeth is often proportionate to the size of the face, but too large for the

amount of space in the arch. Crowding or lapping is the method that nature uses to deliver the

full complement of natural teeth in an arch that is too small to accommodate them.

Crowded and lapped conditions sometimes appear in various facial forms and typal tooth

arrangements, but most frequently in the tapering classification. The crowded, lapped, and

considerably rotated arrangement is typical of the narrow tapering arch, and often is present

when the vault is quite high.

Personalization of Setup by Selective Grinding

One of the most important considerations in producing a natural appearing denture is

personalization, which is possible to introduce by carefully performed, selective grinding

procedures.

It is possible to place lateral incisors in a variety of treatments. In the upper left, the extreme

lapping of a lateral over a central incisor ties the teeth together too closely and can make them

look like a solid band of color in the mouth. An incisal view of the same position of these teeth is

in the lower left. The lateral incisor is too far ahead of the central incisor to give a pleasing

esthetic effect. This position also can cause irritation to the lip and may exert a dislodging

pressure on the denture.

The upper right shows the results of a suggested method for improvement. The mesial aspect of

the lateral incisor and the distal aspect of the central incisor have slight embrasures ground on

them. The central and lateral incisors still maintain contact; however, the lateral incisor is not as

far forward, and the teeth make contact at a slightly different angle.

Slight grinding has softened even more the outline form of the lateral incisor on the distal aspect.

In the lower right, the suggested position of the central and lateral incisors, in addition to the

enlarged embrasure and slight change in outline form, creates the visual effect of a lapped lateral

incisor without actually lapping.

Maxillary Anterior Teeth

These suggestions for arranging anterior teeth pre- suppose the selection of artificial teeth that

are suitable to the patient in form, size, shade, or blend. The procedures used for arranging

anterior teeth differ. The usual method is to place each tooth individually. As each tooth is set, it

is customary to check the alignment of its incisal edge in relation to both the maxillary and

mandibular occlusion rims.

Following are five considerations in positioning or setting anterior teeth;

1. Anteroposterior positioning

2. Anterior slope

3. Mesiodistal inclination

4. Inferosuperior positioning to a horizontal plane (incisal length)

5. Rotation on long axis

Maxillary central incisor

The incisal edges of the central incisors rest on the occlusal plane.

In the frontal view the long axes of the central incisors nearly are perpendicular to the occlusal

plane.

In an occlusal view, the central incisors face forward.

Finally in a sagittal view the central incisors flare slightly in a labial direction

At rest position of the lip-slightly parted-incisal edge of the Central incisor should be

visible I or 2 mm

Mesial angle of the central incisor should be placed 8 mm to 14mm anterior to the center

of the incisive papilla.

While pronouncing F and V incisal edge should meet the dry wet junction of the

lower lip

Anterior plane made perpendicular to the nasion-tubercle or philtrum line.

Plane selection done only after ensuring adequate lip support. Incisal 2/3 of incisor

supports the lip

Lateral incisor

Is in golden proportion / the selected constant proportion to the central

In the frontal view the lateral incisors angle medially.

In a sagittal view the lateral incisors flare slightly more than the centrals in a labial direction

Mesial angle rotated forward in females

Slightly depressed than the central in males

Contact point raised in stepladder fashion

Perceived contact area between centrals 50% of the length of the central.

Between central and lateral 40%.

Between lateral and canine 30%

Distal angle is more rounded

The position of canine teeth plays an important role in the esthetic appearance of natural

dentition. In a denture it plays an equally important role because it influences both the anterior

and posterior tooth arrangement.

Canines

Proper positioning of the upper canines is highly important: the rotation showing the mesiolabial

portion of the tooth, the vertical long axis, and the prominent gingival area with the incisal edge

"tucked in" to harmonize with adjacent incisal areas.

Considerations Affecting Arrangement of Mandibular Anterior Teeth

The long axes of the central incisors are perpendicular to the plane. The long axes of the lateral

incisors incline slightly distally at the neck. The long axes of the canines incline still more

distally at the neck. Such an even "picket-fence" arrangement will not create a natural esthetic

appearance, although it is possible to use it as a starting point of reference.

The horizontal plane used for aligning lower anterior teeth may be above the actual occlusal

plane, a distance usually described as the vertical overlap or overbite. Esthetic and phonetic

needs of a patient affect the amount or degree of vertical overlap of the teeth and, consequently,

the degree of incisal guide- table angulation. It is possible to arrange teeth in harmony with

various degrees of incisal guide-table angulation.

Some prefer to position both the maxillary and mandibular anterior teeth before setting the

posterior teeth. In such instances, the position of the anterior teeth, the amount of vertical and

horizontal overlap (overbite and overjet), and other factors, such as the condylar guidance, plane

of occlusion, and degree of compensating curve desired, may affect the choice of posterior teeth

for a harmonious occlusion.

Mandibular anterior teeth are an integral part of the esthetics and phonetics for complete

dentures. Crowding and/or irregularity in the position of the lower anterior teeth generally mirror

conditions that exist in the upper arch. However, lower anterior teeth are usually more crowded

and irregular than upper anterior teeth with a similar condition.

By careful rotation and inclination and, on occasion, slight proximal grinding and polishing, it is

possible to crowd and lap mandibular teeth, thereby creating a natural esthetic appearance. In

some instances, the lower teeth are much more conspicuous than the upper teeth; particular

attention to their arrangement is essential.

It is necessary to avoid setting the mandibular anterior teeth with their long axes projecting to

one common center. This type of arrangement develops a symmetrical, even, and unnatural

appearance. Rotation of the lower anterior teeth and lapping them produce more characterization

if no two long axes of the teeth are parallel to each other.

Overall Evaluation of Anterior Tooth Arrangement

Although there are many methods and guides for arranging artificial anterior teeth, the overall

visual effect of teeth in the month of the patient resulting from their shape, size, color, and

position determines their acceptance or rejection. The teeth also must fulfill the physiologic,

phonetic, and emotional requirements of the individual patient. This area of dentistry is truly as

much an art as a science. In any given situation, experience and judgment are the final

determinants as to whether a given arrangement of teeth is usable in completing the denture to

the satisfaction of those involved.

The Characterization of the Setup

According to Lombardi”

The central incisors make the best statement of the patient’s age

The lateral incisors connote the patient’s sex.

He also held that the canines reflect the patient’s vigor.

Frush and fisher” believed that dentogenics influence tooth arrangement as well as shade and

tooth selection.

To highlight the age accentuated diastemata and rotations.

To feminize the set up, they rotated the mesial surfaces of the maxillary lateral incisors outward

and blended the cuspids in with other teeth as they rounded the arch.

To masculinize the set up, they rotated the distal incisal corners of the maxillary lateral incisors

outward and gave the canines a more prominent appearance by setting them forward boldly.

They advised against using the diastema between the maxillary central incisors and always

respect the buccal corridors.

Probably the most popular characterization technique is to crowd and tilt the mandibular anterior

teeth; however to be esthetic this must be done in a convincing manner and not simply by a

random scrambling of the setup.

It must be remembered that the best guideline for the setup characterization is an old photograph

or cast of the patient’s natural teeth.

PHONETICS

Phonetics: the branch of linguistics dealing with the study of the sounds of speech, their

production, combination, and representation by written symbols. (American Heritage Dictionary)

Speech is essential to human life, but is often taken for granted. There are six components to

speech: respiration, phonation, resonation, articulation, audition, and neurologic integration.

(Beumer)

Mechanism of Speech

The speech mechanism consists of upper digestive tract and respiratory tract, modified to form

and control valves. The voice is principally produced in the larynx, whilst the tongue by

constantly changing its shape and position of contact with the lips, teeth, alveoli and hard and

soft palates, gives the sound form and influences its qualities. The oral cavity and the sinuses act

as resonant chambers, and the muscles of the abdomen and thorax control the volume, and rate of

flow, of the air stream passing into the speech mechanism.

Breathing - At the beginning of inhalation, nostrils dilate, air proceeds through the nares, and the

nasal cavity, the soft palate relaxes to provide a free passageway to the pharynx, the pharynx is

widely opened, and air goes through the rima glottidis (larynx) through the trachea, to the

bronchi in the lungs. In general, this process is reversed in exhalation. The outward flow of air,

results from coordinated contraction of the muscles of the abdomen, relaxation of the diaphragm,

and "collapse" of the rib cage. Speech has a direct relationship to this exhalation. The sound is

characterized by phonation or articulation (or both) and resonance.

The soft palate in conjunction with the pharynx controls the direction of the air stream after it

passes from the larynx. In all the vowel, and most consonant sounds, the air stream is confined

entirely to the oral cavity, but a few nasal sounds do occur, e.g. M, N, and NG, in which the air is

expelled mainly through the nose. The former are produced by raising the soft palate into close

contact with the pharynx, thus sealing off the nose and forcing the air to proceed through the

mouth.

With the nasal sounds the soft palate is pressed downwards and forwards and the dorsum of the

tongue humped up to meet it, thus sealing off the oral cavity and forcing the air stream to

proceed through the nose. The vowel sounds A, E, I, 0, U are formed by a continuous air flow,

the alteration in size of the mouth and the change in shape and size of the lip opening giving the

various sounds their characteristic form.

The consonant sounds are produced by the air stream being stopped in its passage through the

mouth by the formation of complete or partial seals or stops. These are produced by the tongue

pressing against the teeth or palate, or by the closing of the lips. The sudden breaking of the seal

brought about by the withdrawal of the tongue, or the opening of the lips, produces the sound. In

many sounds there is a build up of air pressure behind the stop which when the seal is released

produces an explosive effect. Examples of these are: the lip closure of the P and B sounds; the

tongue and anterior hard palate contact in T and D sounds.

In some cases the seal or stop is not complete, but the channel through which the air stream must

pass is made extremely narrow: an example of this is the production of an S, Z, or C soft sound,

in which the tongue separates itself from the anterior aspect of the hard palate by about 1 mm.,

forming a thin slit-like channel through which the air stream hisses.

Speech, therefore, is largely a matter of the control of the size and shape of the mouth, which is

chiefly governed by the position of the tongue and its contact with the teeth, alveoli and palate.

Fortunately for the prosthodontists, the tongue possesses remarkable qualities of adaptability,

and rapidly becomes accustomed to changes occurring in the mouth. After the extraction of teeth,

or the insertion of a denture, some difference may be noticed in the quality of the speech, but

improvement quickly follows as the tongue adjusts itself to the new conditions. In extreme cases,

such as the edentulous state or when poorly designed complete dentures are worn, the previous

tone and quality are not always re-established. The tongue's adaptability is illustrated by the

number of individuals wearing dentures, designed with little regard to their effect on phonation,

who exhibit no obviously apparent speech defects; the reason being that in the construction of

those dentures the general principles of setting up were followed, coupled with due regard to the

aesthetic requirements and the attainment of the correct vertical dimension. This has produced

the occlusal plane at a level corresponding to that of the natural dentition, the anterior teeth in

approximately the same position anteroposteriorly as the natural teeth, and the new dental arch

conforming to that of the previous arch, thereby allowing the correct tongue space. Thus the

artificial dentures replacing the lost tissues have conformed closely to the state which existed

naturally, the main difference being the increase in bulk - a factor for which the tongue must

compensate. However, some knowledge of phonetics in relation to dentures is necessary, in order

to correct the speech defects that may occur in denture wearers, and also to act as a guide for the

more accurate construction of complete dentures.

The Physiology of Speech (Martone)

The speech mechanism involves three principle valves:

Valve I: Glottis (True vocal folds of the larynx) the vibrating stream of air passes through the

rima glottidis when voice is desired, this acoustic output is called voice.

This differs from when a person whispers, where the valve mechanism may not be as involved.

The muscles that control the vocal folds are divided into intrinsic and extrinsic. The intrinsic

muscles are a complex set of muscles that adduct and abduct the folds, as well as regulate their

tension and length. The extrinsic muscles connect the larynx with the hyoid bone, sternum,

tongue and pharynx.

Valve II: Palatopharyngeal region (three parts)

Nasopharynx (functions in respiratory system)

Oropharynx (functions on respiratory and digestive systems)

Laryngopharynx (functions in digestive system)

This valve is located where the respiratory/digestive valves cross (pharyngeal isthmus) the valve

divides the pharynx into nasopharynx and oropharynx cavities.

The principal closure is affected by the soft palate into contact with the posterior wall of the

pharynx.

Palatopharyngeal mechanism physiology and anatomy: (Beumer) this region is extremely

important in both phonetics and swallowing (including gagging). At rest, the soft palate drapes

downward so that the oropharynx and the nasopharynx are open to allow for normal breathing.

When called to action (i.e. palatopharyngeal closure required), the middle third of the soft palate

arcs upward and backward to contact the posterior pharyngeal wall at or above the palatal plane.

The lateral pharyngeal wall moves medially and posteriorly to contact the margin of the soft

palate.

Complete closure is required for normal deglutition and the production of some speech sounds

(i.e. plosives) in other phonemes such as vowels and other consonants, the palatopharyngeal port

will be open in varying degrees.

Swallowing is a primary and consistent physiological function, whereas speech is a learned

function. It has been noted that the character of the palatopharyngeal closure during swallowing

differs from speech. In swallowing, the pharynx is more forcefully involved in closure involving

the superior, middle and inferior constrictors firing in overlapping sequence. Whereas, in speech

the superior muscle fibers of the superior constrictor only appear to be involved during closure.

Studies have shown that during swallowing the soft palate contacts the posterior pharyngeal wall

at a lower level than is seen during speech.

Valve III: Orifice of the Mouth (modified by many articulators, mostly by the tongue) The same

events that occur at the vocal folds, occur at the lips and teeth (specifically the mandibular to

maxillary lip, mandibular lip to maxillary teeth, and the tip of the tongue against the alveolar

ridge. There are different forms of pressure (1) pent up pressure (2) overriding pressure (3)

momentary release pressure (4) forming against the obstacle to the breath steam.

There are five basic ways to produce sounds:

Plosive (p,b,t,d,k,g) any sound where there is a complete closure

Fricative (f,v,s,z,th,sh,zh,h) any sound where there is partial closure

Nasal (m,n,ng) forcing air through the velopharyngeal port

Affricate (ch,j) combination of a plosive and a fricative

Glide (w,h,l,r,y) smooth graceful movement of the articulators from one position to another

Innervation of the muscles of speech:

V Trigeminal (soft palate)

VII Facial (periphery of mouth)

IX Glossopharyngeal (pharyngeal muscles)

X Vagus (laryngeal, soft palate, pharyngeal muscles)

XII Hypoglossal (tongue muscles)

The motor innervation is derived from three pathways:

Corticobulbar (conscious control, precise movements’ articulation of speech sounds)

Extrapyramidal (control depth of breath, vocal folds, lips/cheeks/tongue, pharyngeal walls)

Cerebellar (cortex to the speech muscles, automatic coordination)

The Factors in Denture Construction Affecting Phonation

The Vowel Sounds

These sounds are produced by a continuous air stream passing through the oral cavity which is in

the form of a single chamber for the A, 0, U sounds and a double chamber for the I and E sounds,

the division occurring through the dorsum of the tongue touching the soft palate in the post-dam

region. The tip of the tongue, in all the vowel sounds, lies on the floor of the mouth either in

contact with or close to the lingual surfaces of the lower anterior teeth and gums.' The

application of this in denture construction is that the lower anterior teeth should be set so that

they do not impede the tongue positioning for these sounds; that is, they should not be set lingual

to the alveolar ridge. Since the vowels E and I necessitate contact between the tongue and soft

palate, the upper denture base must be kept thin, and the posterior border should merge into the

soft tissue in order to avoid irritating the dorsum of the tongue, which might occur if this surface

of the denture was allowed to remain thick and square-ended.

The Consonant Sounds

For convenience, these sounds may be classified thus:

(a) Labials

Formed mainly by the lips (e.g. B, P, M).

(b) Labiodentals

Formed by the lips and teeth (e.g. F. V, Ph).

(c) Linguodentals

Formed by the tongue and teeth (e.g. Th).

(d) Linguopalatals

Formed by the tongue and palate.

(i) Tongue and anterior portion of the hard palate (e.g. D, T, C (soft), S, Z. R).

(ii) Tongue and portion of the hard palate posterior to that of (i) (e.g. J, CH, SH, L, R).

(iii) Tongue and soft palate (e.g. C (hard), K., G, NG).

(e) Nasal (e.g. M, N, NG - also belonging to the other groups).

Unless careful consideration is given to the following aspects of denture construction, speech

defects will occur varying from the almost indiscernible to the unpleasantly obvious.

1. Denture Thickness and Peripheral Outline

The prosthodontist’s aim is to produce dentures which are mechanically functional, aesthetically

pleasing and permit normal speech. The most satisfactory attainment of the first two

requirements may cause slight defects in the patient's speech but this should not be allowed to

happen and some compromise will often be required satisfactorily to balance these three aims.

One of the reasons for loss of tone and incorrect phonation is the decrease of air volume and loss

of tongue room in the oral cavity resulting from unduly thick denture bases. The periphery of the

denture must not be overextended so as to encroach upon the movable tissues, since the depth of

the sulci will vary with the movements of the tongue, lips and cheeks during the production of

speech sounds. Any interference with the freedom of these movements may result in indistinct

phonation, especially if the function of the lips is in any way hindered.

Most important is the thickness of the denture base covering the palate, for here no loss of

natural tissue has occurred, and the base reduces the amount of tongue space and the oral air

volume. The palate in this instance does not include that part forming the tooth-bearing area -

artificial alveolus.

The production of the palatolingual group of sounds involves contact between the tongue, and

either the palate, the alveolar process, or the teeth. With the consonants T and D, the tongue

makes firm contact with the anterior part of the hard palate, and is suddenly drawn downwards,

producing an explosive sound; any thickening of the denture base in this region may cause

incorrect formation of these sounds. When producing the S, C (soft), Z, R and L consonant

sounds, contact occurs between the tongue and the most anterior part of the hard palate,

including the lingual surfaces of the upper and lower incisors to a slight degree. In the case of the

S, C (soft), and Z sounds, a slit-like channel is formed between the tongue and palate through

which the air hisses. If the artificial rugae are over-pronounced, or the denture base too thick in

this area, the air channel will be obstructed and a noticeable lisp may occur as a result.

To produce the Ch and J sounds the tongue is pressed against a larger area of the hard palate, and

in addition makes contact with the upper alveolar process, bringing about the explosive effect by

rapidly breaking the seal thus formed. The Sh sound is similar in formation, but the air is allowed

to escape between the tongue and palate without any explosive effect, and if the palate is too

thick in the region of the rugae, it may impair the production of these consonants.

2. Vertical Dimension

The formation of the labials P, B and M require that the lips make contact to check the air

stream. With P and B, the lips part quite forcibly so that the resultant sound is produced with an

explosive effect, whereas in the M sound lip contact is passive. For this reason M can be used as

an aid in obtaining the correct vertical height since a strained appearance during lip contact, or

the inability to make contact, indicates that the bite blocks are occluding prematurely. With the C

(soft), S and Z sounds the teeth come very close together, and more especially so in the case of

Ch and J; if the vertical dimension is excessive, the dentures will actually make contact as these

consonants are formed, and the patient will most likely complain of’ “clicking teeth”.

3. The Occlusal Plane

The labiodentals, F, V and Ph, are produced by the air stream being stopped and explosively

released when the lower lip breaks contact with the incisal edges of the upper anterior teeth. If

the occlusal plane is set too high the correct positioning of the lower lip may be difficult, if on

the other hand the plane is too low, the lip will overlap the labial surfaces of the upper teeth to a

greater extent than is required for normal phonation and the sound might be affected.

4. The Anteroposterior Position of the Incisors

In setting the upper anterior teeth consideration of their labiopalatal position is necessary for the

correct formation of the labiodental F, V and Ph. If they are placed too far palatally the contact of

the lower lip with the mesial and labial surfaces may be difficult, as the lip will tend to pass

outside the teeth: the appearance usually prevents the operator from setting these teeth forward of

their natural position. If the anterior teeth are placed too far back some effect may be noticed on

the quality of the palatolinguals, S, C (soft), and Z, in which the tip of the tongue makes slight

contact with the upper and lower incisors: this will result in a lisp due to the tongue making

contact with the teeth prematurely. The tongue will more readily accommodate itself to

anteroposterior errors in the setting of the teeth than to vertical errors.

5. The Post-dam Area

Errors of construction in this region involve the vowels I and E and the palatolingual consonants

K, NG, G and C (hard). In the latter group the air blast is checked by the base of the tongue being

raised upwards and backwards to make contact with the soft palate. A denture which has a thick

base in the post-dam area, or that edge finished square instead of tapering, will probably irritate

the dorsum of the tongue, impeding speech and possibly producing a feeling of nausea. Indirectly

the post-dam seal influences phonation, for if it is inadequate the denture may become unseated

during the formation of those sounds having an explosive effect, requiring the sudden

repositioning of the tongue to control and stabilize the denture; this applies particularly to

singers. Incidentally, speech is usually of poor quality in those individuals whose upper denture

has become so loose that it is held in position mainly by means of tongue pressure against the

palate. Careful observation will show that the denture, in such cases, rises and falls with tongue

movements during speech. Before passing to the next factor it should be mentioned that the

consonants M, N, NO also belong to the nasal group in which the air stream is allowed to escape

into the nasal cavity through a slight channel formed by the incomplete approximation of the soft

palate and pharynx.

6. Width of Dental Arch

If the teeth are set to an arch which is too narrow the tongue will be cramped, thus affecting the

size and shape of the air channel; this results in faulty phonation of such consonants as T, D, S,

M, N, K, C and H, where the lateral margins of the tongue make contact with the palatal surfaces

of the upper posterior teeth. Every endeavor should be made, consistent with the general

mechanical principles, to place the lingual and palatal surfaces of the artificial teeth in the

position previously occupied by the natural dentition.

7. Relationship of the Upper Anterior to the Lower Anterior Teeth The chief concern is that of

the S sound which requires near contact of the upper and lower incisors so that the air stream is

allowed to escape through a slight opening between the teeth. In abnormal protrusive and

retrusive jaw relationships, some difficulty may be experienced in the formation of this sound,

and it will probably necessitate adjustment of the upper and lower anterior teeth

anteroposteriorly, so that approximation can be brought about successfully. The consonants Ch, J

and Z require a similar air channel in their formation.

Let /S/ be your guide (Pound)

The /S/ position: is the most forward and most closed position of the mandible (without tooth

contact) during the enunciation of the /S/ sound. There should be only 1 to 1.5 mm space

between the incisal edge of the lower central incisors and the coronal surface of the upper central

incisors. This position can be used as a three dimensional anterior stopping point.

Verti-centric: a record used in complete denture fabrication. It involves the simultaneous

recording of the vertical dimension of occlusion with the jaws in centric relation (GPT-6)

Posterior speaking space: the space that exists between the posterior and/or the edentulous ridges

when the mandible assumes its /S/ position while functioning at conversational speed. Of clinical

importance in extreme Class II situations.

SUMMARY

To summarize, it will be seen that speech requirements call for dentures having a correct vertical

dimension, an accurate periphery and an arch formation permitting natural tongue space, so that

adequate freedom for movement is ensured. The position of the anterior teeth should be such that

they follow that of the natural teeth, thus fixing the occlusal plane at the correct level and

preventing the placing of the artificial teeth inside or outside the natural arch, which would

require the tongue to adapt itself to new circumstances. Finally, denture bases should be

fashioned suitably thin, but consistent with the other factors of denture construction, so that

contact by the tongue takes place in as near a natural and normal manner as is possible.