Smile design

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guidlenes in smile design

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Smile design : 

Smile design Presented by Dr. P. Baskar PG student Department of conservative dentistry and Endodontics TNGDC

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Guidelines in smile design Shade selection and multidisciplinary approach in smile design

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Guidelines in smile design

Introduction : 

Introduction Dentistry has always been aware of the importance of dental esthetics but recently the patients and many dentists have emphasized this branch of dentistry because of the high value, society gives to a person’s appearance.

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The development of new techniques and restorative materials to meet this new demand has allowed a greater number of treatment options capable of improving or restoring the natural appearance of teeth. These options are becoming more simple and conservative.

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The different factors influencing the smile can be divided into two categories: those which can be changed by the clinician and those which he/she cannot modify. The two main aims of aesthetic dentistry are   to create teeth with pleasing proportions and to create a dental arrangement that is in harmony with the patient’s gums, lips and face.

history : 

history Pierre Fauchard (1678-1761) of France, advocated esthetic practices with the use of gold shell crowns with enamel “veneers”. They also introduced a technique for the manufacture of mineral (as opposed to ivory or bone) incorruptible teeth for use in dentures.

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Transplantation of teeth between patients was practiced, with donors being paid for their trouble. The introduction of mineral teeth in 1817 was soon followed by the manufacture of porcelain teeth. Dentures were fabricated with a gingival component made of carved ivory or animal bone that was designed for adaptation to ivory or bone base. open-faced crown was invented around 1880, the interchangeable porcelain facing was developed in 1880’s, and the porcelain jacket crown came into vogue in the early 1900’s.The three-quarter crown was introduced in 1907.

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In the 1930s, chemically activated acrylic resins were developed. In the 1940s, acrylic-veneer facings came into widespread use. By the 1970s composite resins virtually replaced acrylic resins and silicate cements as “permanent” restorations. Acid etching radically changed cavity treatment by emphasizing conservation of tooth structure. It also allowed for the numerous veneering techniques introduced in the 1970s.Variations include direct resin veneers, commercially produced acrylic “shells”, and laboratory processed veneers of resin and porcelain.

COLOUR, FORM AND LINES : 

COLOUR, FORM AND LINES Colour is the predominant force, taking precedence over form, angles and lines. The difficulty in assessing the value (brightness component) for a shade prescription ,because the eyes are distracted by the colour (hue and chroma components) of the tooth. Form the three basic shapes of a circle, triangle and square. These geometric shapes were, and are associated with religious, mystical and esoteric connotations. The maxillary anterior teeth are a fusion of these basic shapes. Lines The direction of lines can also create optical illusions. Prominent vertical lines on the facial surface of an anterior tooth will infer a longer tooth, while distinct horizontal lines have the opposite effect (wide and short tooth length).

DIVINE PROPORTION : 

DIVINE PROPORTION Proposed by the Pythagoreans’ was the Golden Number, represented by the Greek symbol, ∆. The reciprocal of  is 0.618 and has been termed the Golden or Divine Proportion. Objects, animate or inanimate, whose features or details conform to this ratio, are perceived as having innate beauty

SYMMETRY : 

SYMMETRY defined as static or dynamic. Static symmetry is evidenced by repetition in inanimate objects such as crystals or contrived arrangements . Dynamic (radiating) symmetry refers to repeated proportions in animate, living or vital beings.

UNITY AND HARMONY : 

UNITY AND HARMONY unity in a composition is achieved by incorporating balancing forces as well as a dominant key element. It is important to realize that teeth are arranged with tectonic spacing. Tectonic refers to an arrangement that is both functional and aesthetic needs.

There are two types of visual forces requiring consideration. : 

There are two types of visual forces requiring consideration. cohesive forces, which provide unity and harmony, e.g. two parallel objects or an encircling frame (lips bordering the anterior teeth). The opposite are segregative forces, which convey tension and interest, e.g. objects that bisect each other in a perpendicular arrangement. Segregative forces are essential for avoiding monotony and adding curiosity and variety to a composition.

THE GESTALT PRINCIPLE : 

THE GESTALT PRINCIPLE Dr Max Wertheimer initiated the Gestalt theory of psychology in Germany around 1912, and put succinctly, its definition is “the whole is different from the sum of its parts These concepts allow the observer to achieve a better object-background(figure-ground) relationship by encapsulating the following four constituents: • Proximity • Similarity • Continuity • Closure.

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Proximity facilitates association, linking, grouping, learning, and therefore adds interest. A dental example is teeth arranged adjacent to each other, without diastemae, avoids detachment and aloofness.

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Similarity ensures objects have similar form, colour, position and line angles, e.g. teeth with similar shade, form and arch alignment. Continuity ensures progression, e.g. recurring or repeated ratios from the maxillary incisors to the canines. Closure assures cohesiveness, such as a frame or border, e.g. lips surrounding the teeth.

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Smile design theory can be broken down into at least four parts: facial esthetics, gingival esthetics, micro esthetics and macro esthetics

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Micro esthetics involves the elements that make teeth actually look like teeth. The anatomy of natural anterior teeth is specific for each tooth and that tooth’s location in the dental arch. Specific incisal translucency patterns, characterization, lobe development and incisal haloing all are components of the micro esthetics of each tooth. Dentists and technicians alike endeavor to replicate the micro esthetics of teeth in restorations.

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Macro esthetics The relationship between those teeth and the surrounding soft tissue and the patient’s facial characteristics creates a dynamic and three-dimensional canvas. The artistic work of the dentist and the technician can combine to create a natural and pleasing overall appearance—or not—depending on how well the relative shapes, sizes and arrangement of the individual teeth harmonize with the features of any given patient

MACROESTHETIC DESIGN ELEMENTS: FACIAL MIDLINe : 

MACROESTHETIC DESIGN ELEMENTS: FACIAL MIDLINe to locating the facial midline references two anatomical landmarks. The first is a point between the brows known as the nasion. The second is the base of the philtrum, also referred to as the cupid’s bow in the center of the upper lip. A line drawn between these landmarks not only locates the position of the facial midline but also determines the direction of the midline the midline between the maxillary central incisors should be coincidental with the facial midline. In cases in which this is not possible, the midline between the central incisors should be parallel to the facial midline. If the visual junction of maxillary central incisors is at an angle to the facial midline, it is referred to as a canted midline. Canting is a major design flaw in any natural or restored dentition

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Incisal embrasures. The pattern of silhouetting created by the edges and separations between the maxillary anterior teeth against the darker background of the mouth helps define a good-looking smile. These spaces between the edges of the teeth known as embrasure spaces The size and volume of the incisal embrasures between teeth increase as the dentition progresses away from the midline. the incisal embrasure space between the lateral incisor and the central incisor should be larger than the incisal embrasure between the central incisors. The embrasure between the canine and the lateral incisor should be larger than the embrasure between the lateral and central incisors.

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Connectors. The places in which the anterior teeth appear to touch have been referred to as the connector space. The contact points between the anterior teeth are generally smaller areas (about 2 x 2 millimeters) that can be marked by passing articulating ribbon between the teeth. The connector is a larger, broader area that can be defined as the zone in which two adjacent teeth appear to touch. An esthetic relationship exists between the anterior teeth that are referred to as the 50-40-30 rule. This rule defines the ideal connector zone between the maxillary central incisors as 50 percent of the length of the central incisors. The ideal connector zone between a maxillary lateral incisor and a central incisor would be 40 percent of the length of the central incisor. The optimum connector zone between a maxillary canine and a lateral incisor when seen in lateral view would approximate 30

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Axial inclinations: Each combination of tooth inclinations in a smile is unique. The long axis of, or direction of the anterior teeth in, an esthetic smile also follows a progression as the teeth move away from the midline.

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Shade progression. : Even the shade and color patterns of the maxillary teeth follow a progressive pattern based on the distance from the midline. The maxillary central incisors are the lightest and brightest teeth in the smile. The maxillary lateral incisors have a similar hue to that of the central incisors but are typically just slightly lower in color, or value. The canines have greater chroma saturation and also are lower in value than any of the other anterior teeth. First and second premolars appear lighter and brighter than the canines and have a value similar to that of the lateral incisors. Reproduction of shade progression in anterior restorative and cosmetic treatment re-creates a look that approximates natural esthetics even when patients seek the very lightest shades.

TOOTH REVEAL : 

TOOTH REVEAL "Tooth reveal" is a term for the amount of tooth structure or gingiva that shows in various views and lip positions. Even the most beautiful anterior tooth or teeth will have little esthetic value for the patient if the amount of reveal is unflattering to the face.

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"M" position.: By having the patient say the letter "M" repetitively and then allow his or her lips to part gently, the clinician can assess minimum tooth reveal. While younger patients may show between 2 and 4 mm of maxillary incisal edge in this position, the maxillary incisal edge reveal shrinks and even disappears as people age. In some elderly patients, the mandibular incisal edges begin to show. Carefully locating the "M" position reveal and creating the restoration accordingly can have the fluid effect of making a smile age-specific, being either younger or older in appearance

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"E" position. : When patients say the letter "E" in an uninhibited and exaggerated way, the clinician can ascertain the maximum extension of the lips.. During photographic analysis of the smile, everything that shows can be considered to be in the esthetic zone. Restorative, surgical and periodontal treatment within the esthetic zone should take into consideration both the cosmetic and the health consequences of the result

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Inter-commissure line and lower lip framing. : When a patient’s mouth is in broad smile position, the clinician can draw an imaginary line through the corners of the mouth. This line is known as the inter-commissure line, or ICL. The amount of maxillary tooth reveal below the ICL interacts with the viewer’s perception of the patient’s age. In a youthful smile, approximately 75 percent to 100 percent of the maxillary teeth would show below this line. The position of the incisal edges of the anterior teeth as they relate to the lower lip also may have esthetic consequences. When the visual space created between upper and lower lips in full smile is considered, the maxillary anterior teeth should fill 75 percent to 100 percent of that space to create a youthful look.

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Vestibular space. : In a broad smile, the amount of reveal of the maxillary posterior teeth also can become an esthetic consideration. In patients who have narrow arch form and wide lip extension, tooth reveal behind the canines can be in shadow or disappear completely. This condition has been called deficient vestibular reveal, or DVR.DVR may have negative esthetic consequences in certain patients.

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Smile line. : The plane of the incisal edges of the maxillary anterior teeth also can be related to the two fundamental criteria of midline and reveal. Traditional orientation of the smile line calls for it to be parallel with a line drawn between the pupils of the eyes. When the incisal edges of the maxillary central incisors appear to be below the tips of the canines, the smile line has a convex appearance that can approximate and harmonize with the line of the lower lip. A so-called “reverse smile line” result when the tips of the canines or premolars are longer than those of the central incisors

Various proportion in smile design : 

Various proportion in smile design FACIAL PROPORTIONS DENTAL PROPORTIONS GOLDEN PROPORTIONS GOLDEN PERCENTAGE

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FACIAL PROPORTIONS: Plastic surgeons have long used the idea of proportions to define desirable facial relationships. The rule of thirds divides the face vertically into three approximately equal segments: the superior border of the face is the trichion (ideal hairline), the junction between the upper and middle thirds is the nasion, the junction of the middle and lower third is subnasale, and the inferior border is the menton. If the lower third of the face subsequently is subdivided into thirds, the ideal position of the incisal plane is at the junction of the upper and middle thirds

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DENTAL PROPORTIONS: It has been stated throughout dental literature that the height of the central incisor should be 1/16 the height of the face from ideal hairline to the chin and that the width of the ideal central incisor should be 1/16 the interzygomatic width. Another common rule of smile design is that the widths of the anterior six teeth as viewed from the frontal should be in golden proportion to the intercommissural width.

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GOLDEN PROPORTION : Levin used the golden proportion to relate the successive widths of the anterior teeth as viewed from the frontal. Levin stated that “the width of the central incisor should be in golden proportion to the width of the lateral incisor and that the width of the lateral incisor to the width of the canine should also be in golden proportion as should the width of the canine to the first premolar.

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The width of the central incisor should be multiplied by the value defined as the golden proportion, which is 0.618,or approximately 62%.The resultant width of the lateral incisor should be multiplied by 62% to give the width of the canine as viewed from the frontal. The four front teeth, from central incisor to premolar are the most significant part of the smile and they are in the Golden Proportion to each other. This phenomenon has been combined in a grid which can be used to assist us in perfecting the aesthetics of the eight front teeth.

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GOLDEN PERCENTAGE Snow considered a bilateral analysis of apparent individual tooth width as a percentage of the total apparent width of the six anterior teeth. He proposed the golden percentage wherein the proportional width of each tooth should be: central 25%, lateral 15%, and canine 10% of the total distance across the anterior segment in order to achieve an esthetically pleasing smile

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RECURRING ESTHETIC DENTAL (RED) PROPORTION The RED proportion states that the proportion of the successive widths of the teeth as viewed from the frontal should remain constant as one move distally. Rather than being locked into using the 62% proportion, the dentist can use the proportion of his or her own choosing as long as the dentist is consistent while moving distally. Instead of having to accept the proportion already defined by the widths of the central and lateral incisors, the dentist can define his or her desired RED proportion. The use of RED proportion gives greater flexibility. Although an approximate 70% RED proportion is preferred, the RED proportion should be modified to fit the face, skeletal structure, and general body type of the patient

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USE OF DENTAL PHOTOGRAPHY Dental photography is essential in evaluating a smile. Photographs provide unlimited time as well as the ability to measure the dimensions and proportions of the teeth. An image taken parallel to the facial plane and at least 8 inches away from the teeth should be used to minimize distortion. If the camera is located too close, the teeth are distorted. A 35-mm camera with a 100mm macro-lens set at 1:2 magnification is preferred. A digital camera with similar optical capabilities also may be used. It is important to use a high-quality camera, which gives adequate depth of field, proper lighting, and minimal optical distortion

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RED SMILE DESIGN When working with the anterior six teeth, mathematical formulas for calculating the ideal size of the central incisors may be used. The equation used to determine the ideal width of a central incisor from a predetermined RED proportion is: {(FIVE width of the anterior 6 teeth) / 2(1+ RED + RED2)} = width of central incisor (The RED should be expressed as a decimal <1) Once the width of the central incisor has been established, the height can be determined by using the formula: (Width of central incisor / Width-to-height ratio) = height of central incisor (The width-to-height ratio should be expressed as a decimal <1) The anterior six teeth are the only teeth clinically in which the individual mesial and distal FIVE dimensions of the teeth can be altered significantly by making changes in the widths of the existing teeth. Because all evaluations are done using the facial image view, the FIVE widths of the premolars and molars are modified more easily

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FRONTAL VIEW REFERENCE LINES The interpupillary line is determined by a straight line that passes through the center of the eyes and represents, if parallel to the horizontal plane, the most suitable reference for carrying out correct facial analysis. SYMMETRY AND DIVERSITY In most subjects in whom asymmetry is found, the dimensional difference between the left and right sides of the face is less than 3%.This is therefore considered the limit beyond which a facial irregularity becomes evident to the eye of the observer.

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FACIAL PROPORTIONS A well- proportioned face can be divided vertically into three portions of equal size. The upper third of the face is the area between the hairline and the ophriac line, the middle third runs from the ophriac line to the interalar line and the lower third extends from the interalar line to the tip of the chin. The lower third of the face plays a significant role in determining the overall esthetic appearance. The distance from the bottom of the nose to the lower edge of the upper lip should be approximately half the length between the lower lip and the bottom of the chin.

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LATERAL VIEW PROFILE Appropriate clinical evaluation of the lateral view is a determining factor in successful completion of an esthetic examination of the patient.     NORMAL PROFILE The profile is evaluated by measuring the angle formed when three reference points on the face are joined together: glabella, subnasale and soft tissue pogonion. The lines that join these three elements normally form an angle of roughly 170 degrees. CONVEX PROFILE In a patient with a convex profile, the angle formed by joining the three reference points is substantially reduced, creating a marked posterior divergence.

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CONCAVE PROFILE In patients with a concave profile, the angle formed by joining the three reference points is greater than 180 degrees, creating an anterior divergence. E-LINE One useful element in determining the profile type is an evaluation of the position of the lips with reference to an ideal line that joins the tip of the nose to the tip of the chin. According to Ricketts, in a normal profile, the upper lip is about 4 mm posterior to the E-line, while the lower lip is about 2 mm posterior.

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The lips Shape Labial philtrum Lip movements

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TOOTH EXPOSURE AT REST When the teeth are at maximum intercuspation, the lips touch lightly and the incisal third of the maxillary incisors is covered by the wet surface of the lower lip.   When the mandible is in the rest position, the teeth do not come into contact, the lips are slightly apart, and a portion of the incisal third of the maxillary incisors is visible, this varies from 1-5mm,depending on the height of the lips and the patient’s age and sex Vig and Brundo reported that on average, the maxillary incisors are exposed more in women when at rest than in men (3.4 versus 1.91mm) and that young patients show them much more than middle-aged patients(3.37mm versus 1.26mm)

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INCISAL EDGE Identification of the position of the incisal edge, in both the apico-coronal (incisal curve) and anteroposterior (incisal profile) directions, represents a fundamental aspect of the esthetic diagnosis

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FLAT OR REVERSE INCISAL CURVE Sometimes abrasion of the incisal edges can lead to a flat or even a reverse incisal curvature, producing unpleasant effects from an esthetic point of view. HORIZONTAL SYMMETRY A flat incisal plane, with uniform tooth length and the reduction or disappearance of the interincisal angles, gives the smile horizontal symmetry. This causes the loss of the so-called cohesive force in the dentofacial composition, creating an unattractive esthetic effect and an inevitable sense of “aged” smile.

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INCISAL PROFILE The incisal profile is the position of the incisal edge in the anteroposterior direction and is contained within the inner border of the lower lip. This allows adequate closure of the lips, so they can come together without any interference from an incorrectly positioned incisor. SMILE LINE The first step in this analysis is to evaluate the exposure of the anterior teeth during smiling. On the basis of the amount of dental and gingival display in the anterosuperior area, Tjan and coworkers identified three types of smile lines: low, average, high.

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The various factors that can cause this excessive visibility of the soft tissue are A short upper lip Labial hyper motility Altered passive tooth eruption Anterior dento alveolar extrusion Excessive vertical development of the upper maxilla

phonesis : 

phonesis a function that is closely affected by the relationship between the teeth, the lips, and the tongue, and it can be significantly compromised by the presence of inadequate restorations. Pronunciation of the sounds of m, e, f/v, and s can be a valuable aid in identifying some of the functional and esthetic parameters to be followed when creating the treatment plan.

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THE ‘M’ SOUND When the patient is in the rest position, a space between the arches exist, ranging on average from 2 to 4 m, that is never completely occupied by the teeth (i.e., the free space) LENGTH In addition to helping establish the postural interocclusal position, the m sound can also provide useful information about incisal length. In the interval between one pronunciation and the next, the clinician can evaluate the portion of the central incisor that is visible in the rest position, which will help to determine the modifications that need to be made to the incisal length. The possibility of shortening or lengthening the incisal third of the anterior teeth must be assessed on the basis of the amount of tooth exposure, the sex and the age of the patient, their requests, and the overall evaluation of the clinical considerations.

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THE ‘E’ SOUND   INCISAL LENGTH Prolonged pronunciation of the vowel sound e is another aid in phonetic evaluation of the incisal length of the maxillary teeth. While pronouncing this sound a space can be seen between the upper and lower lips that are occupied only partially by the maxillary incisors. The size of this space varies from one patient to another, depending on age. YOUNG PATIENTS: When young patients pronounce the letter ‘e’, the space between the upper and lower lips is, as a rule, occupied almost entirely by the maxillary incisors. The incisal edge is therefore brought very close to the lower lip. If the maxillary teeth occupy less than 50% of this space, they can normally be lengthened to occupy as much as 80% of the space between the lips. ELDERLY PATIENTS: Because of the reduced tonicity of the perioral tissues in elderly patients, the space between the upper and lower lips is only partially occupied by the maxillary incisors. The incisal edge may therefore be short of the lower lip. This allows for lengthening of these teeth which, in any case, should not occupy more than 50% of the space, so as not to seem excessively long in patients who are no longer young

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THE F/V SOUNDS INCISAL LENGTH AND INCISAL PROFILE Correct pronunciation of the sounds f and v is produced by light contact between the maxillary central incisor and the vermilion border of the lower lip  Air compression that occurs when the hard surfaces of the maxillary incisal margins meet the soft surface of the lower lip during pronunciation of the letters f and v produces the appropriate sounds. Fluent pronunciation of these sounds means that the maxillary incisors are the correct length and that their incisal profile is positioned adequately.   The vermilion border therefore represents the buccal limit within which the incisal margins of the restorations are to be positioned. When the incisal margin just touches the lower lip, the incisal length can be considered suitable. If there is any separation between the teeth and the lip during pronunciation, the suitability of the length of the anterior teeth must be evaluated on the basis of the results of the other phonetic tests (i.e., m and e) and analysis of the other tooth and dentolabial parameters

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THE S SOUND Correct pronunciation of the s sound is determined by the uniform passage of a wide, flat band of air that is forced between the hard surfaces of the maxillary and mandibular anterior teeth.

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TOOTH TYPE The different tooth forms can be correlated invariably to sex or personality and specific age Certain aspects that can provide useful indications for defining the most appropriate tooth type are: Recreating correct tooth type lies in the natural teeth adjacent to those being restored or, in their absence, those in the opposing arch. Use of old photos or models of the patient is indispensable for determining the original form of the teeth. The gingival architecture and the periodontal biotype can provide indications as to the most suitable form and contour to the restoration.

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COLOUR When observing the natural dentition, a significant difference in colour can be seen between the teeth in both arches. The maxillary central incisors are the lightest teeth in the mouth and therefore dominate the tooth composition not only because of their size, but also because of their brightness. In most individuals, the lateral incisors appear to be the same hue as the central incisors but slightly less intense, and therefore they look much less bright. The canines, both maxillary and mandibular, often show a much more intense chroma, sometimes appearing much darker than the teeth adjacent to them. The premolars are of a similar color to the lateral incisors, therefore distinguishing themselves from the canines. The color of the tooth depends on the thickness of the enamel and the level of saturation of the dentin.

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In the cervical area, the reduced thickness of the enamel makes the color of the dentin more evident, producing greater chromatic saturation. Thicker enamel, on the other hand, produces a marked translucency in the incisal third, where phenomena of fluorescence and opalescence combine with those of total light reflection caused by the inclination of the incisal edge. When restoring anterior teeth, due consideration must be given to re-creating a natural color progression and the color obtained in this way will represent the new point of reference for the restorative therapy.

Other factors that influence in smile design : 

Other factors that influence in smile design Tooth position and arrangement Arch shape Tooth crowding

Functional aspects : 

Functional aspects Occlusal relationships Maximal intercuspal position Centric relation Centric occlusion Anteroir guidance Incisor guidance Canine guidance Overjet and overbite

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ESTHETICS AND FUNCTION In the past, esthetics and function were considered two separate aspects and optimization of esthetics often involved functional compromise.   Nowadays, the functional aspect must represent the starting point for achieving esthetics. The re-establishment of a natural appearance achieved by creating restorations that are not only increasingly difficult to distinguish from natural dentition but also allow the achievement of both correct function and an ideal esthetic appearance.

CONCLUSION : 

CONCLUSION It is well recognized that the smile has great influence on facial esthetics and one’s general appearance. This new emphasis on esthetics is changing the focus of dental practice from restoring carious teeth to treating healthy teeth to making them more esthetic.

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THANK YOU To be continued as……………………. SHADE SELECTION AND MULTIDISCIPLINARY APPROACH IN SMILE DESIGN