Presentation on theme: "Short Learning Objectives"— Presentation transcript:
1SELECTION AND ARRANGEMENT OF ARTIFICIAL TEETH IN COMPLETELY EDENTULOUS PATIENTS
2Short Learning Objectives Anterior teeth selectionPosterior teeth selectionArrangement of Teeth
3INTRODUCTIONThe selection of artificial teeth for edentulous patients requires a knowledge and understanding of a number of physical and biologic factors that are directly related to each patient.Careful examination of the faces and teeth of people with natural teeth will develop a sense of dentofacial harmony that is the objective of tooth selection and esthetics.There must be harmony of color, form, size, and arrangement of teeth
4Anterior tooth selection The factors of shade selection are:-1. Age.2. Sex.3. Complexion.4. Patient -preference
5METHODS USING PRE-EXTRACTION GUIDES It includes-Diagnostic casts,Photographs,Radiographs,Extracted teeth
6Anterior tooth selection Factors to be considered for selection of anterior teeth:A. Shade (color)B. SizeC. Form
7METHODS USING ANTHROPOLOGICAL MEASUREMENTS- These methods measures certain anatomical dimensions and derive the size of teeth using certain formula-
8Circumference of the head Width of the upper CI=13bi-zygomatic widthTotal Width of the upper anterior =3.364Total Width of the lower anterior =---- Width of the upper anteriors
9METHODS USING ANATOMIC LANDMARKS Seven anatomic entities are used as guides to selection of anterior teeth for size:Size of the faceSize of the maxillary archIncisal papilla and the cuspid eminence or the Buccal FrenumMaxillomandibular relationsThe contour of the residual ridgesThe vertical distance between the ridgesThe lips
11THE VERTICAL DISTANCE BETWEEN THE RIDGES: The length of the teeth is determined by the available space between the existing ridges.THE LIPSWhen 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 lipIn 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.It is best demonstrated when the letter F, as in fifty five is pronounced
12FORM OF ANTERIOR TEETH:- The form and outline of the anterior teeth can be determined using the following factors:Shape of the patient’s face or facial formPatient’s profileDentogenic concept
13Typal form theory: Leon Williams (1917) According to this, the shape of the teeth should be inverse of the shape of the face. Teeth form can be-square,ovoid andtapering
14Dentogenic conceptDentogenics is the art, practice and technique of creating the illusion of natural teeth in artificial dentures and is based on the elementary factor influenced by sex, personality and age of the patient.It was first described by Frush and Fisher.
15Dentogenic concept:Sex:In female, the incisal angles are more rounded and the teeth have lesser angulation while in males, the incisal angles are rounded to a lesser degree.The incisal edge of the CI is parallel to the lips and the laterals are above the occlusal plane in males But in females it follows curve of the lower lip (CI & LI)The distal surface of CI are rotated posteriorly for females, LI overlapping CI.Reverse in males, providing masculine features.
17Dentogenic concept: Age: separated into young, middle or elderly. Due to decrese in muscle tone, sagging of the cheeks and the lower lips occur. To prevent cheek biting, horizontal overlap of the posterior teeth can be increase.Inter occlusal distance reduces with age. Hence, mandibular teeth are more visible than the maxillary teeth.In old patients the teeth tend to have square form due to attrition, round features disappears and line angle quite prominent in those patients.
18Dentogenic concept:Age:Old patient have gingival recession, & can be reproduced in the denturesThe color of the teeth also changes with age.Personality:It seems reasonable that a large vigorous type of persons have teeth of a size and form with prominent markings, different from those of a delicate appearing patient.
21MATERIALS OF TEETH:- There are two main types: 1. Porcelain, 2. AcrylicPorcelain teeth:- vacuum fired and air fired. The vacuum is better because they are harder and have luster. Generally porcelain teeth are preferred particularly for young person because they look more vital, very smooth and difficult to abrade.
22MATERIALS OF ANTERIOR TEETH:- Acrylic teeth:They are made from acrylic resin, indicated when there is insufficient inter-occlusal distance, and grinding becomes necessary, also in situation where there are opposing natural teeth, partial denture and gold bridge. They are inferior when they are compared with porcelain because they can not maintain luster for long time and abraded easily.
23MATERIALS OF ANTERIOR TEETH ACRYLIC TEETH : 1- Not brittle, but poor abrasion resistance. 2- Esthetic very good. 3- Chemical bonding with denture base. 4- Easily ground and polish. 5- Transmit fewer forces to the mucosa. 6- No clicking on contact. 7- Thermal expansion same as acrylic denture base. PORCELAIN TEETH : 1- Brittle, more resistance to abrasion 2- Excellent (does not stain). 3- Mechanical bonding by pins or undercuts holes. 4- Difficult to grind and polish. 5- More forces to the mucosa. 6- Clicking on contact. 7- Much lower than acrylic causes stresses in acrylic denture base.
24Posterior tooth selection Posterior teeth are selected for color, buccolingual width, mesiodistal length, vertical height (occluso-gingival length) and occlusal form. 1- Shade (color): - should be harmonized to the shade of anterior teeth, maxillary first premolars are sometimes used for esthetic more than function, so it's advisable to select premolar teeth with lighter color than the other posterior teeth, but not lighter than anterior teeth. Generally the shades of posterior teeth are slightly darker than anterior teeth.
252-Bucco-lingual width:- - should be slightly narrower than natural teeth to decrease occlusal surfaces which direct less stress during function to supporting tissue, and also enhance the development of the correct form of polished surfaces of the denture.3- Mesio-distal width:Narrower than natural ones.should be equal to the distance between canine line and anterior border of maxillary tuberosity for upper teeth. For lower teeth should be equal to distance between canine line and anterior border of retro molar pad area.
264- The occluso-gingival height - Controlled by the available inter-arch distance. The length of the maxillary first premolar should be comparable to that of maxillary canine to have the proper esthetic effect. The height of posterior teeth usually divided into long, short, medium. Long posterior teeth are generally more esthetic in appearance than are shorter teeth.
275- Occlusal form:Selecting the tooth to be used is based on the concept of occlusion to be developed, the philosophy of occlusion to be fulfilled, and the accomplishment approached. It is given in the table below.
28COMPARISION OF DENTURE TOOTH MOLDS AND OCCLUSAL CONCEPTS TOOTH MOLD ADVANTAGEDISADVANTAGE20 or 30-degree cusp teethCentric jaw record, face bow, protrusive records to semi-adjustable.Set upper anterior and posterior teeth, then lowers to cross-arch contact or “balanced-occlusion”Reported slightly more efficient in chewing testsPosteriors appears more naturalMost time and complexity of recordsLimitations of anterior tooth positionsRestriction of posterior tooth positions to that allowed by Cuspal anatomyMonoplane 0-degreeCentric jaw record onlySimple articulatorSet 12 anterior teeth with Overjet but no overbiteSet lower teeth in flat plane to middle of retromolar padSet upper to match; no attempt on contact on excursionsSimplest of all recordingsSimplest articulatorsQuick arrangement of teethWide range of posterior tooth positions possibleNo lateral stresses on mucosa with parafunctionEasier for patients with uncoordinated closuresFlat premolars may appears less estheticReported as less aestheticsAnterior esthetics need more Overjet and no overbiteSELECTION
29COMPARISION OF DENTURE TOOTH MOLDS AND OCCLUSAL CONCEPTS TOOTH MOLD ADVANTAGEDISADVANTAGEFlat teeth with compensating curve or second molar rampCentric jaw recordSemi-adjustable articulatorAnterior teeth with Overjet and slight overbitePosterior set to contact on at least 1 point on non-working or balancing sideSimple to set up; allows for more esthetic overlap of anterior teethThe posterior point contact maintain denture base stability on excursion or parafunctionSlightly more laboratory set upPremolars appear flat if visibleCombination or “lingualized” occlusionMonoplane lower posterior teeth set to retromolar padAnatomic upper posterior teeth set with only lingual, not buccal cusp touchingUpper premolars appear naturalSome range of posterior tooth position allowedReported slightly better chewing than monoplaneSome grinding needed to create upper cusp tip/lower fossa contactsSELECTION
32Arrangement Of Anterior Teeth It is important that the artificial anterior teeth are placed in the same antero-posterior position and at the same length as natural teeth to provide adequate esthetics and phonetics.
33RESIDUAL ALVEOLAR RIDGE In patient with long edentulous period, much bone could have been lost from the residual alveolar ridge. In this situation, artificial teeth should not be placed against the ridgeAs a general rule: the longer the natural teeth have been out the farther the artificial teeth should be from the ridgeThe teeth should be placed closer to the residual ridge when there is less shrinkage and farther from ridge when there has been more resorption
35RELATIONSHIP TO INCISIVE PAPILLA Incisive papilla is a guide to anterior tooth position because it has a constant relationship to the natural CI.A line marking the centre of the incisive papilla on the cast is extended forward onto the labial surface of the cast and CI are set on either side of this line. However in few cases, where facial mid line doesn’t coincide with papilla, better to take facial midline as guide.Incisive papilla is also a guide to the antero-posterior position of the teeth. Labial surfaces of the CI are usually 8-10 mm in front of the papilla
36Incisive papillaeMidline of upper dentureDr Abhilash
40Horizontal overlap (over jet) and Vertical overlap (over bite):
41Arrangement Of The posterior Teeth Standardized parameters1. Curve of Wilson' as transversal compensating curve.2. Curve of Spee' as sagittal compensating curve.3.Optimum intercuspation of the antagonists.
43Common errors in arrangement of teeth. Lack of rotation of anterior teeth to give a narrower effect.Setting mandibular anterior teeth too forward in order to meet maxillary teeth.Failure to make the canine the turning point of the arch.Setting mandibular 1st premolar to the buccal side of the canines.Setting the mandibular posterior teeth too far to the lingual side in the 2nd molar region which cause tongue interference and mandibular denture displacementFailure to establish the occlusal plane at the proper level and inclination.Establishing the occlusal plane by an arbitrary line on the face.
44Take Home Message…..Teeth selection should be in harmony in color, shape and size with the patient’s face, sex and age for a successful fabrication of complete denture prosthesis.Teeth should be positioned in harmony with intraoral and circumoral muscle activity and adjusted so that they occlude and articulate evenly.Several different prosthetic tooth molds have been produced, and each has some purported advantages. In the absence of a clear advantage, tooth molds, selected should be esthetically pleasing and have a simple procedure to set up.
45MCQs Dentogenic concept was given by- Boucher Frush and fisher Rudd Winkler
462. Distance of labial surfaces of the central incisors from incisive papilla is- 5-7mm6-8mm8-10mm10-12mm
473. Total width of upper anterior as compared to bizygomatic width is- 1/31/5
484. Antero-posterior compensating curve is provided by- Curve of WilsonCurve of MonsonCurve of speeCurve of Berry
495. Total Width of lower anterior as compared to upper anterior is 2/34/55/6