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TEETH SELECTION

TEETH SELECTION. INTRODUCTION. The anterior teeth are primarily selected to satisfy esthetic requirements, whereas the posterior teeth are primarily selected to satisfy masticatory requirements.

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TEETH SELECTION

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  1. TEETHSELECTION

  2. INTRODUCTION The anterior teeth are primarily selected to satisfy esthetic requirements, whereas the posterior teeth are primarily selected to satisfy masticatory requirements. The selection of teeth and their arrangement to meet esthetic requirements demand artistic skill in addition to scientific knowledge. There are no rules of thumb for this procedure; however, there are anatomic landmarks and manufactured aids that can be used as guides.

  3. DENTOGENIC CONCEPT

  4. DENTOGENIC( Frush and Fisher,1955) is a coined word meant to convey in reference to prosthetic dentistry exactly the same meaning as the suffix -genic imports to photograph in the word “photogenic”. • In our word dentogenic we seek to describe only such a denture as is “eminently suitable” in that for the wearer, the denture adds to that person’s charm, character, dignity or beauty in a fully expressive smile. • Dentogenics then means the art, practice and techniques used to achieve that esthetic goal in dentistry.

  5. Esthesia means sensibility or sensation • Esthetic is the adjective form, meaning responsive to the beautiful art or nature. • When the dentogenics evolved the full meaning of esthetics was carried out into it’s three dimensions: first, the wearer of a dentogenic restoration must have an inner sensibility of well being; second, the viewer of a dentogenic restoration must percieve beauty or a fulfillment of the wearer’s personality in his smile; the third requisite would then follow without cavil, in that the dentist who created the dentogenic restoration would feel deeply rewarded.

  6. SPA FACTOR ( SEX, PERSONALITY AND AGE)

  7. INTERPRETATION OF SEX Expression of feminine characters • Roundness, smoothness and softness that is typical of women. The feeling of softness is typical of feminine form • Select a mold which expresses softer anatomic characteristics or one which is highly adaptable to being shaped and formed into a delicate type of tooth by certain recommended grinding procedures

  8. Expression of masculine characters • A schema of masculine form illustrates cuboidal, hard, muscular , vigorous appearance which is typical of men • Masculanity expresses aggressiveness boldness, hardness, strength, action and forcefulness • Harshness and angularity • But some men have a qualifying softness which will guide to compromise the typical hardness of a masculine tooth interpretation

  9. As an introductory rule the positioning of teeth has to depart from the compact wall of porcelain which is usual characteristics of the denture look. • Effort should be to introduce lively positions which are harmonious because they are inspired by the most pleasing natural tooth arrangement, but this should not be confused with unpurposeful irregular teeth

  10. The Central Incisor • The two positions of the central incisors, set in perfect symmetry, are the starting positions for conventional tooth setups. By bringing the incisal edge of one central incisor anteriorly, we create a position which is evident but harsh. However, if we move one of the central incisors from the starting position out at the cervical end, leaving the incisal edges together we have created a harmonious lively position. This is the least noticeable of the three positions which are to be described.

  11. The second and more vigorous position is to move one central incisor bodily anterior to the other. • The third position is a combined rotation of the two central incisors with the distal surface forward, with one incisor depressed at the cervical end and the other depressed incisaIly.

  12. The Lateral Incisors • The lateral incisor rotated to show its mesial surface whether slightly overlapping the central incisor or not, gives softness or youthful coquettishness to the smile. • By doing the reverse, that is, by rotating the lateral incisors mesially, the effect of the smile is hardened We would select the soft positions for the very feminine smile, and the hard positions for the vigorous. • It is important to note that Nature never repeats herself, and in the mouth, we avoid symmetry of tooth positions on both sides of the mouth

  13. The soft position (S) of the lateral incisor is produced by rotating it’s mesial surface outward and inward rotation produces hard position (H)

  14. The Cuspid Teeth The cuspids should never be set with the tip of the tooth out labially further than the cervical end, except in very rare instances where ,we have to harmonize the arrangement with a rough or primitive type of patient. • A prominent cuspid eminence gives to the cuspids greater importance and therefore gives to the smile a vigorous appearance more suitable to the masculine sex.

  15. General, we will adopt for the cuspid conjointly the three following positions: (1) out at the cervical end, as seen from the front (2) rotated to show the mesial face (3) almost vertical as seen from the side

  16. THE THIRD DIMENSION-DEPTH GRINDING • The "denture look" is due mostly to the flat appearance of the artificial upper anterior teeth, their lack of depth, or of "body." The depth grinding is done on the mesial surface of the central incisor only. Central incisors are the widest, almost always the longest, and therefore, the most noticeable of the six anterior teeth. It is necessary to develop the desired effect in the depth grinding by consideration of these main factors:

  17. a flat thin narrow tooth is delicate looking and fits delicate women ( little depth grinding) • a thick bony big sized tooth heavily carved on it’s labial surface is vigorous and to be used exclusively for men ( severe depth grinding) • For the average patient the depth grinding will be an average between delicate and vigorous • Depth grinding reduces the width of the central incisor according to the severity of grinding to be accomplished.

  18. INTERPRETATION OF PERSONALITY FACTOR There are three divisions of personality spectrum : • Delicate meaning fragile, frail, the opposite of robust (5%) • Medium pleasing meaning normal, moderately robust, healthy and of intelligent appearance (80%) • Vigorous meaning opposite of delicate; hard and aggressive in appearance, the extreme male animal, muscular type almost primitive and ugly(15%)

  19. An approach to the problem of selecting a mold category, is analysis of the patient according to his position in the spectrum. • This is the first step to the consideration of the mold category and not the exact mold selection per se. • When we incorporate the personality factor in esthetics we do so keeping in mind the influence of the sex and age factors as we proceed.

  20. INTERPRETATION OF AGE • Symbols of youth in the natural teeth are lightness of shade, the unblemished form of the newly erupted teeth, earliest appearance of the mameIon is present at the incisal edge of the central and lateral incisors. The cuspid presents a pointed tip which is very sharp in appearance. • The mamelon is soon abraded away, and the tooth assumes the youthful adult form evidenced by the enamel incisal edge of variable depth and of bluish hue.

  21. Later the sharp tip of the cuspid wears down to a more mature form. As we advance along the chronologic life line of the individual, normal wear, plus trauma, and, in some instances, malocclusion, and disease make inroads upon the original purity of tooth form. The tooth ages with the individual, and, very often, the mouth condition gets far ahead of the chronologic life line. • In the artificial tooth, then, we may reflect the appropriate age effects by such means as grinding the incisal edges and removing the incisal enamel at such an inclination and to such depth as to convey reality to composition.

  22. The sharp tip of the cuspid suggests youth, and, as age increases, it should be judiciously shaped, not abruptly horizontally flattened, but artistically ground so as to imply abrasion against opposing teeth. • In advanced age; the bicuspids should be "softened" on the tips of the cusps to avoid the appearance of recently erupted teeth. In the natural teeth, we have seen the effects of erosion high on the gingival third and the necks of teeth. Sometimes it is very advanced, at other times it is of a lesser degree. This erosion imparted to the artificial tooth, by careful grinding and polishing very effectively, conveys the illusion of vigor and advanced age

  23. E SHOWS UNNATURAL ABRASION

  24. PRINCIPLES OF COLOR

  25. HUE • Hue is the name of the color. • ROY G. BIV is the acronym for the hues of the spectrum. • In a younger patient hue tends to be similar throughout the mouth. With aging, variations in hue often occur because of intrinsic and extrinsic staining from the restorative materials, food, beverages, smoking and other influences.

  26. CHROMA / SATURATION • Chroma is the saturation or intensity of the hue and therefore chroma can only be present with the hue • For example, to increase the chroma of a porcelain restoration more of that hue is added. • Chroma is the quality of hue that is most amenable to decrease by bleaching. Almost all hues are amenable to chroma reduction in vital and non-vital bleaching. • In general chroma of teeth increases with age.

  27. VALUE / BRILLIANCE • Value is the relative whiteness or blackness of the color • A light tooth has a high value; a dark tooth has a low value • It is not the quantity of the color gray but the quality of brightness on a gray scale • That is does the shade of color ( hue+ chroma) seem light and bright or dark and dim • The use value does not involve adding gray but rather manipulating colors to increase or decrease the amounts of grayness

  28. VALUE IS THE MOST IMPORTANT FACTOR IN SHADE MATCHING. IF THE VALUE BLENDS, SMALL VARIATIONS IN HUE AND CHROMA WILL NOT BE NOTICEABLE.

  29. TRANSLUCENCY It is the property of the of an object that permits the passage of light through it but does not give any distinguishable image. Translucency of artificial teeth has the effect of mixing the various colors (hues) of the porcelain with the changing colors in the oral cavity

  30. HUE SENSITIVITY After 5 seconds of staring at a tooth or shade guide the eye accommodates and become biased. If one stares at any color for a longer than 5 seconds and then stares at a white surface or closes one’s eyes the image appears, but in a complimentary hue. This phenomenon is known as hue sensitivity and adversely affects the shade selection After 5 seconds, look away or stare briefly at a blue surface which will readapt the vision to orange-yellow portion of the spectrum ( most involved in color matching )

  31. ANTERIOR TOOTH SELECTION • Pre extraction guide • Size of anterior teeth • Form of anterior teeth • Color of teeth

  32. Pre Extraction Guides • Preextraction guides include photographs, diagnostic casts, radiographs, the teeth of close relatives, and extracted teeth. Size Of Anterior Teeth Seven anatomic entities are used as guides to select anterior teeth for size Size Of The Face. • The average width of the maxillary central incisor is estimated to be one sixteenth of the width of the face measured between the zygoma

  33. The combined width of the six maxillary anteriors is slightly less than the one third of the bi zygomatic breadth of the face, the face bow can be used as caliper to record the bi zygomatic width of the face Size Of Maxillary Arch • Make the measurements from the crest of incisal papilla to the hamular notches and from one hamular notch to the opposite notch. The combined length of the triangle in millimeters is used on the selector. The circular slide rule indicates the tooth sizes, anterior and posterior, for both arches.

  34. Incisal Papilla And The Canine Eminences Or The Buccal Frenum. • Measure the distance 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. The combined width of the six maxillary anterior teeth is determined in millimeters

  35. After the occlusal rim has been properly contoured and the vertical height has been established , the rim is placed to position in the mouth. The patient is requested to relax his lips touching. A pointed instrument is used as a marker is passed to the occlusal rim at each corner of the lips and a mark is recorded. The mark is passed on a line parallel to the pupil of the eyes. The distance between the marks following the contour of the arch measured in mm is the combined width of six maxillary anterior teeth

  36. Maxillomandibular Relations: Any disproportion in size between the maxillary and the mandibular arches influences the length, the width; and the position of the teeth. 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.

  37. The Contour Of The Residual Ridges The artificial teeth should be placed to follow the contour of the residual ridge. 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.

  38. 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. • 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. • 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.

  39. 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. Form Of Anterior Teeth Form refers primarily to the outline of anything, and shape is the quality of a thing that depends on the relative position of all points composing its outline (facets, developmental grooves, grooves from wear or abrasion, cuppings and convexities) • 3 factors are used as guide

  40. The Form And Contour Of The Face • The form of a tooth should conform to the contour of the face as considered from the labial, mesial, distal, and incisal aspects. • To determine the facial profile, observe the relative straightness or curvature of the profile. Check three points: the forehead, the base of the nose, and the point of the chin. If these three points are in line, the profile is straight. If the points of the forehead and of the chin are recessive, the profile is curved.

  41. Shapes of the artificial teeth chosen to be in harmony with the size of the patient’s face

  42. A tooth viewed from the mesial or distal should conform to the contour of the profile

  43. The indicator may be used in one of two ways to establish the facial outline

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