ESTHETICS IN COMPLETE DENTURE

Diagnosis and treatment planning

Impression making

Maxilomandibular relationship

Teeth Selection

Arrangement of teeth

Orientation of occlusal plane

Occlusal rims

Setup characterization

Denture base

Artistic reflections

Patient’s acceptance of arrangement of teeth

1

Introduction:

Over the past century, the dentists have written about and debated the various elements of complete denture esthetics. During the past 50 years, however significant improvement have been made in the quality of denture teeth and materials, which allow for dentures to be far more esthetic than ever before.

A denture usually perceived as esthetic when the teeth and bases are in harmony with facial musculature. A denture usually is noted to be unrealistic when a disharmony exists. The lack of harmony could be anything from incorrect size and shape of the teeth to an improper orientation of occlusal plane.

Thorough patient evaluation is essential if good denture esthetic to be achieved. The patients personality, cosmetic index, and various physical factors all impact on the esthetics. All pre-extraction records are invaluable, old casts, photographs, or immediate dentures can be extremely helpful both for tooth selection and arrangement. Particular attention should be directed to tooth angulations and special characteristics such as rotations, crowding or diastema.

Principles of visual perception and their practibility to Denture prosthetics

Lomardi defines the science of visual perception as a psychologic response

The principles of visual perceptions are organised into 2 broad categories:

- Composition

- Proportion

Composition: Defined as relationship that exist between the objects (teeth) that are made visible when illuminated by sufficient light when individual smiles or laugh by contrast in colour line and texture. Any dental composition can be esthetic or unesthetic depending how these elements are combined. The natural teeth to be pleasing are arranged in repetition of their shape (outline form) line (axial inclination and

2

position) and colour. This provides unity to the composition. However, the unity is not static. There is no bilateral symmetry. The size of maxillary right and left central incisor are rarely identical. This gives dental composition a subtle variety. There is another factor called dominance unity with subtle variety and dominance of one factor (shape, line or contour) over arrangement will result in pleasing natural composition. One feature that will be dominant in all human dentition is central incisor.

Proportion: The pleasing repeated proportion between the teeth that progress from central incisors to the posterior teeth is critical in achieving proper esthetic harmony. The proportion is based on elements of repeated ratio and illusion.

Repeated ratio: An example of golden proportion comes under repeated ratio only when a line is divided methemetically into segments that exhibit ratio of 0.618:1 does the golden portion exist. Also the ratio of smaller to the greater is same as proportion of greater to whole. Applying this principle to dentition; the anterior teeth are most pleasing when their width’s are related to one another in golden proportion.

Illusion: The teeth between CI and most visible posterior tooth appear to be proportionally reduced in size progressing posteriorly. This is principle of gradation of size and thus illusion aids in achieving pleasing dental composition. Feature of illusion is also aided by amount of light striking the teeth (illumination). When viewed intraorally CI appear lighter because of arch position and amount of light it receives. Buccal corridor has light reducing potential area of oral cavity.

Esthetics in complete denture is developed during various steps of denture fabrication.

These are:

1. Diagnosis and treatment planning:

A careful evaluation of mental attitude of the patient pay rewarding dividends because there are always preconceived hopes and undertaking. A determination of these desires before starting the treatment is mandatory for these may be vast differences between what the patient hopes to receive and what can be expected. Patients vary in

3

their emotional responses regarding esthetics from an obvious attitude of indifference to the demanding state where entire life seem to center around the appearance of oral cavity. The mental harmony between patient and dentist must exist or failure is inevitable.

2. Impression making:

This visit is also called the appearance phase visit.

The length and thickness of all denture border are important in establishing pleasing facial contours.

Natural appearance of lips in relation to base of nose is of prime importance. Improperly formed labial denture borders which produce tension and extreme fullness of lips are detrimental to facial expression.

Denture border may require variations in length and fullness from one side to other to produce an acceptable nose and lip contour because of teeth of symmetry between right and left sides of face. Hence denture border should be determined by recording functional position of vestibular sulcus when final importance is made. This is preferable to carving the border from processed acrylic resin base.

Labial surface of maxillary occlusal rim is contoured to the fullness required to support upper lip naturally in comfort and function.

Thus form should be adjusted with consideration for the orbicularis oris muscle and its attachments. The muscles of facial expression are unable to functional normally without adequate lip support since their length from origin to insertion is shortened due to inward sagging of orbicularis oris.

Wax occ. rims should also allow for esthetic buccal corridor (bilaterally).

3. Maxillomandibular relationship:

Proper orientation of occlusal plane is very important step to develop esthetically pleasing dentures. Anteriorly it is determined by esthetic and phonetic requirements and posteriorly it should be parallel to camper line or ala-tragus line.

4

The midline of the denture should be in harmony with the midline of the face and this is established during this stage.

Recording of proper vertical dimension is another important step:

An excessive vertical dimension is associated with undesirable strained and artificial effects while an insufficient vertical dimension creates unattractive changes characteristic of the aging process. In later situation the chin comes too close to note, compresses the upper lip at centre and allows the corner of mouth to drop. However, the final vertical dimension represents a series of compromises between the mechanical and esthetic requirements.

Correct registration of new relation is very important from stand point of esthetics. Patients sometimes complain that since a denture is inserted the face has become asymmetrical. The common cause is faulty registration of jaw relationship or occlusal error.

4. Tooth selection:

Tooth selection involves choice of shade, size and shape of the artificial teeth.

Tooth shade:

Historically, shade selection was based on the patients hair, eye color, complexion, and age. Boucher made the point, however that hair colour changes throughout life and actually can be changed abruptly by artificial coloring. He further pointed out that the colour of the iris of eye involves such a small area that its influence on tooth shade is negligible. He recommended that teeth be harmonious with skin colour. Several authors have noted that teeth darken naturally with age and, therefore, recommended that darker shades be selected for older individuals. Besides matching the shade to the patient’s complexion and age, Krajickek emphasized the necessary consideration of the patients desires. No matter how harmoniously the dentist matches the shade to a patient’s age and complexion, the patient will never accept the result if it does not meet his or her expectations.

In the mid 1950, Frush and Fisher introduced the “dentogenic” concept for establishing the esthetics of a patients complete dentures.

5

Their theory was based on a patients sex, personality and age. They also tended to use darker shades in men or patients with bold and vigorous personalities. Conversely they used lighter shades in women and patients with delicate personality.

Clark established the fact that natural teeth are not monochromatic but rather consist of three distinct shades:

1. Cervical

2. Incisal

3. Transitional (In the middle 3rd)

Clark also explained that shade itself possesses three dimensions.

1. Hue - The basic colour of the spectrum

2. Brilliance (valve) - The brightness or reflectance; and

3. Saturation (Chroma) - the intensity of the hue

In order to simulate natural teeth, denture teeth manufacturers fabricate modern artificial teeth with intrinsic blends of shades and translucencies.

In general there is more chroma in the cervical area and more translucency in incisal area of the anterior teeth. In addition, there is a transition of the shade from the central incisors to the canines. The canine are less translucent, more opaque, and have more chroma than the central incisors.

Make it easy for you and your patient to view their faces in good light. Your patient should be able to stand before a north facing window, and you should have adequate colour corrected lighting. Give your patient a hand mirror about 6 inches (or 15 cm) in diameter.

Allow your patient to select the colour of teeth they prefer.

The careful selection of tooth shade can some times be used either to emphasize or to mask tooth irregularities for instance, in cases of mandibular prognathism when the teeth are edge to edge. The selection of dark lower anterior teeth may help to mask the abnormality of jaw

6

position. Similarly in patients with Angles Class II, Division I, jaw relationship the selection of darker maxillary incisor or lighter mandibular incisors can appear to reduce the overjet to some extent.

Tooth size:

Generally, the larger people have larger teeth. In addition men usually have larger teeth than women, particularly when comparing the maxillary lateral incisors. Sharry, Boucher and Pound all condemned the practice of selecting teeth based on the measurement of the master cast. All agreed that the size selection should be based on the facial measurements and proportions.

There are two popular methods in classic literature to select the appropriate size of the maxillary anterior teeth.

The first is to base the selection on the space available for placement of teeth. The length of maxillary wax rim first is established by phonetics (i.e. fricative [“F” and “V”] sounds) and adequate support for the soft tissues of the upper lip. The length of maxillary central incisor is measured from incisal edge of maxillary wax rim upto the high lip line (smile line of the upper lip). Vertical lines then are scribed on the wax rim directly down from the right and left alae of nose. The distance between these lines give a good approximation of the width of the six maxillary anterior teeth and places the canines near commissures.

The second preferred method of tooth size selection is based on the facial and tooth size proportion. Pound emphasized harmony in the proportion of the maxillary anterior teeth and the face. In his writing, he advocated the same 1:16 ratio described by House and Loop. In his research, house established a biometric ratio of 1:16 both for length of maxillary central incision compared with length of the face and also for the width of the maxillary central incisor compared with the bizygomatic width of face.

Levin observed that the width of maxillary anterior teeth when viewed in the frontal plane lie within the “Golden proportion” of 1.618 (i.e. the central incisor is 1.618 times wider than the lateral incisor, etc. is a frontal view. he suggested that a grid set up in this proportion be used as an aid in arranging the anterior teeth to achive maximum esthetics.

7

Frush and fisher varied incisor length from the ideal according to the dentogenic guidelines of age, sex and personality. The incisors tend to be longer in young individual and to get shorter progressively with age. In addition the incisors of men are proportionally shorter than those of women. This variation of course is meant to simulate attrition. Frush and Fisher like Pound, emphasized the importance of the incisal edges of the maxillary anterior teeth following the contour of the smile line of the lower lip. Whenever a dentist establishes the size of the maxillary incisors by esthetic and phonetics or by anatomic proportions, it is prudent for him or her to query the patient for pre-extraction records, such as dental casts, radiographs, or photographs to help establish the ideal tooth size for an individual patient.

Any disproportion in jaw size between the maxillary and mandibular arches influences the length, width and the position of teeth will have to vary from accepted normal if 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.

Tooth form:

Berry was the first to demonstrate the correlation between the outline form of maxillary central incisor and the inverted outline form of the face. Leon Williams applied the typal forms of facial art to the classification of the maxillary anterior teeth and thereby gave profession a much improved method for tooth shape selection. Williams classified facial forms as square, tapering, square tapering and ovoid.

Following an 18 year of study of extracted teeth House and Loop classified teeth according to form. Their classification was based not only on facial outline form of tooth but also on mesial distal and gingivo incisal contours as well. They proposed three pure typal forms i.e. square, tapering and ovoid along with six other combination forms i.e. square tapering, reverse tapering, ovoid square, ovoid tapering and square tapering ovoid, House held that good esthetic could be achieved only if the face, arches and tooth shapes all were in harmony. In addition he classified arch forms as square, tapering and ovoid. Frush and Fisher considered dentogenic factors when selecting tooth size and

8

shade. Each denture tooth was treated as an individual in terms of path position and form. Overaccentuated maxillary central incisors produce strength and boldness in the smile. This can be reinforced or softened by thoughtful position of maxillary lateral incisors. The position of maxillary canines is of paramount importance for achieving good esthetics. The shape of the maxillary canines further reinforces the statement made by maxillary incisors. Frush and Fisher also emphasized the importance of maxillary bicuspids in complete denture aesthetic because they are so visible during expressive smile.

Feminine tooth forms generally are ovoid or a combination type that includes the ovoid form. Conversely masculine tooth forms generally are square or a combination type that includes the square form. Frush and Fisher recommended beginning the denture set up with the basic typal tooth form required by patient. Depending upon his or her dentogenic factors, the dentist can feminize the patient’s appearance further by softening the lines of arrangement of set up.

5.Tooth arrangement:

There are four steps in arranging denture teeth.

1. The proper orientation of occlusal plane

2. The careful development of wax rims precisely in the space intended for the artificial teeth.

3. The placement of each tooth in its correct anatomic position (care should be taken to create as much symmetry as possible from one side of the arch to the other).

4. The characterization of the set up (This is achieved by crowding, rotation of teeth, placement of diastema, and variations in the angulation of the teeth to personalize the set up for an individual patient).

6.Orientation of occlusal plane:

In the sagittal view the occlusal plane is determined by the incisal edges of the maxillary central incisors and the approximate juncture of the upper and middle thirds of retromolar pad. The occlusal plane lies

9

parallel to Camper’s line in the sagittal plane and parallel to interpupillary line in the frontal plane.

The occlusal plane device desinged by Frank Fox is a most useful for determining these two relationships. The lengths of the maxillary central incisors are established best by esthetics and phonetics. The length is adjusted to where the wet or dry line of the lower lip makes light contact with the incisal edges of the maxillary incisors.

7.Occlusal rims

The wax rim should be developed with great care to fill the space once occupied by the patients natural teeth and should offer adequate support for the soft tissues of the face. They should allow for esthetic buccal concidors (bilaterally). Sometimes in abnormally resorbed ridge relations maxilllary teeth might be placed too far bucally where they obliterate the buccal spaces, resulting in harsh, ugly and toothy appearance. If the occlusal plane is oriented properly, the maxillary wax rim should follow the smile line of lower lip. Orientations lines should be scribed on the maxillary rim in the midline (facial midline; the high lip line, smile line and two vertical lines in the canine area directly down from the alae of the nose. Arch form, according to House and Loop should be harmonious with facial form and tooth form.

Heartwell and Rahn pointed out that mandibular teeth becomes more visible with age.

Veg and Brundo showed that men on average, displayed 1.23 mm of the mandibular incisors when the lower lip was at repose, where as women only displayed 0.49 mm. Cade showed in his research that there is significant exposure of mandibular teeth beyond age 40 and that in a patient over 40 the mandibular anterior teeth affect esthetics as much as maxillary anterior teeth. After the occlusal plane and maxillary rim have been established, the positions of incisal edges of the mandibular central incisors can be established very nicely with Pound closest speaking space technique. The mandibular anterior teeth are set so that their incisal edges are slightly lingual to the incisal edges of maxillary incisors. In case of retrognathic patient, the mandibular incisors are tipped forward as far as possible for better esthetics, where as in a prognathic patient they are tipped lingually to prevent or atleast to minimize an anterior crossbite.

10

8.Individual tooth placement:

The incisal edges of the central incisors and canine rest on the occlusal plane, where as lateral are about 1mm short of the plane. In a frontal view, the long axes of the central incisors nearly are perpendibular to the occlusal plane. The lateral incisors angle medially slightly. The canine usually angle more medially them the lateral incisors. The tips of canine should never be more labial than their necks. In an occlusal view, the central incisors face forward, where as the canine are rotated distally, displaying more of their mesial surfaces. The incisal edges of the canines parallel the alignment of the posterior ridges. Finally in the saggital view, the central incisors flare slightly in a labial direction, where as the lateral incisors flare slightly more in the same direction. The long axis of canines, however, nearly are perpendicular to occlusal plane in this view.

Placement of mandibular anterior teeth, in frontal view the long axes of central incisors are perpendicular to the occlusal plane. The lateral incisors are tipped medially slightly. The long axes of the mandibular canine tip more medially than the lateral incisors. In a saggital view the central incisors are tipped in a labial direction slightly. The long axis of the lateral incisors nearly are perpendicular to the occlusal plane in this view. The mandibular canine angle forward slightly.

Set up characterization:

Lombardi felt that the central incisors make the best statement of the patients age whereas the lateral incisors connotes the patients sex. He held that canines reflect the patients vigor.

Frush and Fisher believed that dentogenics influence tooth arrangement as well as shade and tooth selection.

1.To highlight age they accentuated diastema (between lateral incisor and canine)and rotations.

2.In addition, Frush and Fisher varied the long axes of the teeth and flattened the smile line.

11

3.To feminize the set up, they rotated the mesial surfaces of maxillary lateral incisors outward and blended the cuspids in with the other teeth as they rounded the arch.

4. To masculinize a set up they rotated the distal incisal corners of the maxillary lateral incisors outward and gave the canine a more prominent appearance by setting them forward boldly.

9.Denture bases

Sir Wilfred Fish He went to great lengths to explain the relationship between the polished surface of the denture and complete harmony of the facial musculature and soft tissue.

Frush and Fisher, in keeping with their dentogenic theory, proposed convex, rounded, and shortened papilla in older patients. They also proposed the exposure of more of the cervical root portions of the denture teeth in order to simulate the gingival recession seen in older individuals. They stippled their dentures but were careful not to stipple the free gingiva. They recommended using finer stippling along with a lighter base shade in females and a darker base shade along with heavy stippling and a rougher base texture in males. They preferred to tint the interdental papilla and muscle attachment areas with a deeper shade of red. Conversely they used light shade to tint areas of hard tissue.

A number of classic writers of complete denture literature advocated anatomically, correct festooning, meticulous stippling, and custom staining of the denture base. They also suggested the use of preformed anatomic palatal and facial gingival forms.

Pound and Choudhary both suggested the use of diagram that maps out the area to be stained with each colour. This technique is based on the use of five shades of Kayon denture base stains.

H - Basic pink used over hard tissue as attached gingiva

F - Light red used for papilla and muscle attachment.

A - Medium red used sparingly

E - Purple used sparingly in heavily pigmented gingiva

12

B - Brown used for healthy pigmented gingiva

10.Artistic reflections:

1. Vary the slant of long axis

2. Place the teeth so that tips of lateral incisors show when the patient speaks seriously, the amount depends upon age and sex, less for old than for young people and more for woman than men.

3. Create symmetry in divergences of proximal surfaces of teeth from contact point.

4. Place one central and lateral incisor parallel to midline and rotate the other central and lateral incisor slightly in posterior direction.

5. Place one maxillary central incisor slightly in an anterior direction to other central incisor.

6. Place the neck of one max. central incisor in posterior direction and neck of other CI in anterior direction.

7. Create asymmetry for max. right and left cuspids. Rotate one in posterior direction than other. Place the neck of one in more lateral direction than the other.

8. Create a good smiling line by proper placing the max. posterior teeth mediolaterally in relation to cheek. When the teeth are placed to laterally the buccal corridor is eliminated, resulting in harsh, ugly and toothy appearance.

Similarity in shape and size of mandibular anterior teeth presents a problem in positioning for esthetics. The esthetic appearance can be enhanced by:

Grinding the incisal edges.

Rotating and overlapping the teeth to give an irregular appearance.

Creating asymmetry in divergence of proximal surfaces of teeth from contact points.

13

Creating a slight diastema between lateral and cuspid on one side.

Varying the direction of long axis.

11.Patient acceptance of arrangement of teeth:

Patient must be given the opportunity to observe and approve the final arrangement of teeth in try-in appointment. Patient should not be permitted to observe the trial denture in mouth until dentist is satisfied with the composition as it is created. If possible another adult member of family should be asked the patient during normal conversation. Immediate appearance with new dentures - On insertion of CD that restore the tip to its pre-extraction position, the stretch of labial musculature shortens the upper lip and patient shows more teeth than desirable. However, during the first few weeks after insertion the labial musculature accommodates to the presence of denture and lips adopt a more natural position.

14