Presentation on theme: "Classification of patients 1.Patients with remaining natural teeth 2.Patients who have old denture 3.Patients without remaining natural teeth and without."— Presentation transcript:
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
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.
Guides for the anterior teeth selection 1.Pre-extraction guides a.Study cast b.Photographs c.Radiographs d.Extracted teeth
2.Post extraction guides -Selection of size (width and length) a.Size of the face and head b.Size of the contour 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 mandibular teeth are frequently larger than normal
-Width of the anterior teeth a.Bizygomatic width – The average width of the maxillary central incisor is estimated to be 1-16 of the bizygomatic width that is, the distance between the cheek bones measured just in front of the ears. Some simple devices are available from tooth manufacturers for making this determination or caliper may be used to measure this distance. A face bow maybe used as caliper to make this determination. The combined width of the six maxillary anteriors is slightly less than one third the bizygomatic width.
b.The width of the nose – An estimation of the position of the apex of the upper natural canine can be found by extending parallel lines from the lateral surface of the ala of the nose onto the labial surface of the upper occlusion rim. c.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. d.Canine eminence e.Cranial circumference
f.Incisine papilla – It has been found that a transverse line bisecting the incisive papilla will pass through the middle of the upper canines. The necks of the upper anterior teeth overlap the anterior ridge by 1- 2 mm cervically, and the incisive edges of the centrals must show below the relaxed lip by 1-2 mm in a young person and less than half that amount in an elderly patient. 1.The vertical distance between the ridges – Is determined by the available space between the existing ridges. 2.The lips 3.Vertical overlap
4. The length width ration of the patients face. Length of face Width of face = Length of tooth Width of tooth
Selection of the form -Guides for selecting the form of anterior teeth. -Shape of the arch.
Tooth form in relation to arch form -Shape of the face Selection of shade -Color and shade of tooth N.B. The shade consist of: a.Hue i.e specific color b.Saturation i.e. amount of color per unit area. c.Translucency i.e ability of color to permit light to pas through it.
Patients age – With age, darker, while lighter teeth are suitable for young patients. Patients complexionlight teeth for fair skin, blue eyes, dark teeth usually for dark skin and black eyes.
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. b.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. -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.
The color should be matched with the skin of the cheeks. General consideration for selection of anterior teeth 1.Sex a.Females – All teeth are more curved, rounded line and point angles, the teeth more ovoid or tapeing than square. b.Male – The teeth are larger with sharp line and point angles, the teeth more square than ovoid or tapeing. 2.Age 3.Personality
Posterior teeth selection – Posterior teeth should have a small bucco-lingual width to keep forces on the supporting structure to a minimum. The mesiodistal measurements of the upper posterior teeth is taken from the distal surface of the canine to the prominence of the tuberosity. The total mesiodistal width of the four posterior teeth is often used as a mould number. The lower posterior teeth should not extend posterior to the mesial border of the retromolar pad.
It is advisable to select upper posterior teeth as long as possible so that the premolars will be esthically in harmony with the canine. Actually there are long, medium and short posterior teeth.
Anatomic teeth -Balanced occlusion -Young healthy patients -Good ridges Non anatomic form or monoplane teeth -Flat occlusal surfaces (without cusp) -Not function efficiently -Balanced occlusion -Less destructive force to the tissues -Old patients having poor ridges with poor neuromuscular control.
Advantages of anatomic teeth. 1.Esthetically acceptable 2.More efficient in cutting of food, thereby reducing forces that are directed to the supporting structures during masticatory movement. 3.They can be arranged in balances occlusion
Disadvantages of anatomic teeth. 1.It is mandatory to use an adjustable articulator. 2.Eccentric records must be done for articulator adjustments 3.Clinical remount is essential to adjust the occlusion after denture settling. 4.Balanced occlusion lost when settling occurs. 5.More horizontal forces during functions. 6.Frequent relining, Fast bone resorption
Advantages of non anatomic teeth 1.Comfortable 2.The allow greater range of movements which is necessary in patients with mal-related jaws (as those with Para functional jaw habits or wide mandibular movement) 3.Non anatomic teeth exerts less horizontal or torquing forces, so they are used with flat ridge cases. 4.Centric record only is needed 5.When the neuromuscular control are so uncoordinated, the jaw records are not repeatable
Disadvantages of non anatomic teeth. 1.They are of unnatural look 2.Less cutting efficiency 3.The flat teeth occlude in two dimensions only, but the mandible has 3 dimension movements.
Porcelain teeth -Wear is clinically insignificant over a long period of time -No significant loss vertical dimension -Allow for the total rebasing procedures -Maintain communicating efficiency -Difficult to grind and fit into a close inter-ridge space -Cause dangerous abrasion to opposing gold crown and natural teeth. -Have a sharp impact sound -Will not bond to the base material except with mechanical means. The anterior porcelain teeth have pins at the back, while the posteriors have holes.
Acrylic resin teeth. -Wear is clinically significant -Loss of occlusal vertical dimension due to wear. -Occlusal surface is altered by wear. -Do not chip, and have softer impact sounds -Easy to adjust and polish -Easy to grind into close inter ridge space -Will bond to base material by chemical union. -Minimal wear to opposing natural teeth and gold crowns. This is a definite indication for their use
Acrylic teeth are used in the following situations 1.Limited inter-arch distance 2.Maxillary single denture against natural dentition. 3.Maxillary single denture opposing partial denture 4.Opposing natural teeth with gold occlusal surfaces
Upper and lower posterior teeth can be -Both porcelain -Both acrylic -A combination of porcelain and acrylic resin teeth on opposing dentures can be used. It softens the impact sounds, reduces friction and eliminates chipping. -Upper posterior porcelain anatomic teeth with non anatomic lower resin teeth -Upper and lower posterior acrylic teeth with upper anterior porcelain teeth is contraindicated because the resin teeth will wear rapidly resulting in occlusal destruction of the underlying tissues.