Selection of artificial teeth

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Selection of Artificial Teeth for completely edentulous patients : 

Selection of Artificial Teeth for completely edentulous patients

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Definition: The selection of a tooth or teeth of a shape, size and color to harmonize with the individual characteristics of a patient. Classification of patients: 1. Patients with remaining natural teeth 2. Patients who have old denture 3. Patients without remaining natural teeth and without old denture

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Objectives: 1. Esthetics 2. Masticatory function 3. Correction of speech defects 4. Preservation of the remaining tissue and muscle tone - Primary selection of the teeth must be carried out at the first appointment.

Anterior teeth selection : 

Anterior teeth selection Guides for the anterior teeth selection: Pre-extraction guides Study cast Photographs Radiographs Previous partial dentures 2. Post extraction guides Extracted teeth Old dentures of the patient

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When pre and post extraction records are not available or not useful in selection of anterior teeth, then the following methods can be used: Selection of size (width and length) a. Size of the face and head b. Size of the maxillary arch c. Maxillomandibular relations i. In class I – Normal relationship, the teeth in one arch are compatible with the teeth in the other arch. ii. In class II – The mandible is retruded and the mandibular teeth are frequently smaller iii. In class III – The mandible is protruded and the mandibular teeth are frequently larger than normal

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Size of anterior teeth Size of the face Width of maxillary central incisor = 1/16 bizygomatic width of the face Width of the alae of the nose If the base of the nose is wide the central incisor should be wide, if the root of the nose is narrow the lateral incisor should be narrow.

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Cranial circumference Size of maxillary arch Not dependant in sever resorption Corners of the mouth The distance measured between the two commisures (angles of the mouth ) will represent the width of the upper six anteriors from the distal surface of the canine to the distal surface of the other canine. A mark is placed at occlusion rim at each corner of the lips when the patient is relaxed

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Incisal papilla & cuspid eminences Distance = width of six maxillary anterior teeth Line drawn from the distal termination of the eminence (or anterior to buccal frenum attachment) following the contour of the ridge , reaching the anterior border of incisal papilla, then terminate distal to canine eminence of opposite side

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Vertical distance between the ridges Length of the anterior teeth The lips Length of the anterior teeth High lip line (when the patient smiles) : cervical third of anterior teeth Low lip line (when the patient relaxed) : incisal third of anterior teeth

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Maxillomandibular relations Mandibular anterior teeth size & length Retruded mandible : the mandibular anterior teeth smaller Protruded mandible : the face is longer the mandibular anterior teeth longer Contour of residual ridges Direction of resorption (HW)?

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Form of anterior teeth The form & contour of the face Square, taper, or ovid Sex Curved features = female Square features = male Age Older age = outline more square

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Color or shade of anterior teeth Patients age – With age, darker, while lighter teeth are suitable for young patients. Patients complexion—light teeth for fair skin, blue eyes, dark teeth usually for dark skin and black eyes.

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The following facts are true for nearly all natural teeth: a. The neck of the tooth has a more pronounced color than the incisive edge. The incisive edge if not worn, is more transluscent that the body of the tooth and is usually of a bluish shade (composed entirely of enamel) c. The upper central incisors are lightest teeth in the mouth followed by the laterals and canines. Posterior teeth are usually uniform in color. d. Teeth darken slightly with age.

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Aid for selecting the shade Shade guides – The shade guide tooth should be moistened and selection made in the normal light. a. Outside the mouth along the side of the nose. b. Under the lip with the incisal edge exposed c. Under the lip with only the cervical end covered and the mouth open.

Posterior teeth Selection : 

Posterior teeth Selection Shade of posterior teeth Shade of posterior teeth should harmonize with the shade of anterior teeth (bicuspids)

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Size & number of posterior teeth Buccolingual width Buccolingual width of artificial teeth less than natural teeth to reduce the size of food table but don’t lose the support for cheeks, & not great enough to embarrass the tongue or encroach on a normal buccal corridor

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Anteroposterior dimensions Anteroposterior dimensions of posterior teeth are determined by the edentulous area between the distal of canine and the maxillary tuberosity in maxillary arch and between the distal of canine and the ascending area of the mandible in mandibular arch.

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Why? To place teeth on the ascending area of the mandible would direct the forces at an inclined plane, which are more dislodging than forces directed at right angles to the support

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Vertical height The height of the maxillary first premolar should be comparable with that of the maxillary canines to have the proper esthetic effect

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Occlusal form Cusp angles are measured from a horizontal axis when the tooth is set with its long axis perpendicular to the horizontal axis Based on occlusal form, posterior teeth classified as: Anatomic teeth Semianatomic teeth Non anatomic teeth Special forms of teeth

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Cusp form teeth ( anatomical teeth ): Were designed for the function of mastication. Their cusps were arranged so that during closing movements they would shear & crush food when the patient applied a reasonable biting force. Indications In well formed ridges where good support and retention can be expected. Where balanced occlusion is planned. Patient with good neuromuscular control.

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Advantages: Ease in developing bilateral balanced articulation between the maxillary & mandibular teeth during eccentric movements Excellent esthetic quality Chewing usefulness Disadvantages: Possible damage to the supporting tissues due to deflective contacts when vertical dimension is lost through resorption When bone loss occur lead to denture movement , discomfort, irritation of soft tissue,& more bone loss

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Monoplane teeth ( non anatomical teeth ) They were designed without cusps to allow for intercuspation anywhere along the occlusal plane anteroposteriorly. Indications They are indicated in flat ridge cases to minimize the lateral destabilizing forces. When balanced occlusion is not planned. In abnormal jaw relationships or when it is difficult to record centric relation as in patients with poor neuromuscular control. Patients with cross bite tooth relations. Patients with deleterious habits such as bruxism.

Advantages: Freedom in movement Used in class II & class III jaw relation ships Closure of jaws over a broad contact area Minimal horizontal pressure Easier maintenance Fabrication of dentures with simple techniques & articulators Disadvantages: Lack of esthetic quality Less chewing efficiency

Material composition of teeth : 

Material composition of teeth Acrylic resin teeth Less resistant to wear & staining Less likely to chip or fracture Chemical means of retention with the denture base Used in cases of small inter arch distance. Why? Ease of occlusal reshaping Used in cases where the opposing teeth (natural or have metalic restorations). Why? Porcelain teeth More resistant to wear & staining More likely to chip or fracture Mechanical means of retention with the denture base Not used in cases of small inter arch distance. Why? No occlusal reshaping Not used in cases where the opposing teeth (natural or have metalic restorations). Why?

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