Presentation on theme: "OF ARTIFICIAL TEETH FOR COMPLETELY"— Presentation transcript:
1OF ARTIFICIAL TEETH FOR COMPLETELY SELECTIONOF ARTIFICIAL TEETH FOR COMPLETELYEDENTULOUS PATIENTSProf.Dr. Ahlam El-SharkawyHead of prosthodontic departementPharos University in Alexandria
2IntroductionThe anterior teeth are primarily selected to satisfy the esthetic requirement , where as the posterior teeth are primarily selected to satisfy the functional requirements .The anterior teeth are composed of six maxillary and six mandibular teeth.
3OBJECTIVES FOR TOOTH SELECTION TO CONSTRUCT THE COMPLETE DENTURE THAT…………1. FUNCTION WELL EFFICIENTFOR MASTICATION.2. ALLOW PATIENT TO SPEAK NORMALLY.3. ESTHETICALLY PLEASING.4. PRESERVE TISSUE STRUCTURES OF THE GNATHODYNAMIC SYSTEM5. SHOULD MAINTAIN THE VERTICAL DIMENSION
10a. Bizygomatic distance The average width of the maxillary central incisor is estimated to be 1:16 of the bizygomatic widthBizygomatic width the distance between the cheek bones measured just in front of the ears.
11a. Bizygomatic distance The combined width of the six maxillary anteriors is about one third the bizygomatic width.
12b. The width of the noseAn estimation of the position of cusp tip 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.
14c. Corners of the mouthThe 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.
15Corners of the Mouth Mark corners at rest (#7 wax spatula) Position of distal of the canines
16LengthThe necks of the upper anterior teeth overlap the anterior ridge by 2-3 mm cervically, and the incisive edges of the centrals must show below the relaxed lip by 2-3 mm in a young person and less than half that amount in an elderly patient.
17Amount of tooth shown About 2 mm of teeth are shown when lip is relaxed.
18High Lip Line Highest point of upper lip when smiling Cervical necks lie at or above this lineIf shorter teeth are selected, esthetics compromised
19Guidelines for Setting Anterior Teeth High Lip LineCorner of MouthAngulation is as important as midline
20FORM OF THE ANTERIOR TEETH .The guides for selecting the form of anterior teeth :1- Shape of the face.2- Shape of the arch.
211-The shape of the face .According to Leon Williams classification the human face has been classified intoThree typesSquareTaperingOvoid
23The shape of the maxillary central incisor coincides with the inverted form of the face
24Selection of the form Shape of the face. It was claimed that the shape of the upper central incisor bears a definite relationship to the shape of the face.Thus if one of these teeth is enlarged and the incisal edge placed above the brows with the neck of the tooth on the chin, then the outline of the tooth would nearly coincide with that of the face.
25SQUAREFacial form- the width of the forehead, zygomatic arch and mandibular angle is equal.Profile- straight and flat ala areaIncisal form- mesial and distal lines are almost parallel till the length of 2/3rd from incisal edge.
27ovoidFacial form- width of zygomatic arch is wider than the distance of forehead.Profile- ovoid ala areaIncisal form- mesial and distal lines are curved.
28TaperingFacial form- the width becomes narrow from forehead towards the zygomatic arch and mandibular angle.Profile- curved or flatIncisal form- mesial and distal lines become narrow from incisal edge to cervical end.
30Patient’s sex and age: A cuboidal tooth form is required for the males A spheroidal form for the females.Teeth for males should have a less convexity than for females.The incisal edge of older patient is flat to resemble attrition of natural teeth.
31Dentogenic concept (SPA) Sex, personality, age are the factors which will determine the form of the anterior teeth
32PersonalityThe dentist should select and arrange teeth so that it improves the patient’s personality. The patient can be vigorous ore delicat.More squarish and large teeth are selected for vigorous people
33Feminine MUSCULINE Prominent teeth Smaller teeth Large sized teeth Square arch formSquare labial surfaceSquare incisal edges and cornersDarker shadeFlat smiling lineCanine – cervical area is more visible and prominentFeminineSmaller teethRound cornersCurved contours & arch formCurved labial surfaceRound incisal edges and cornersDelicate appearanceCurved smiling lineCanine – mesial 3rd only seen
34Age Younger people Older people Lighter shade More incisal translucencyMinimal wear of incisal edgeCurved smiling linePointed caninesOlder peopleDarker shadeLess incisal translucencyincreased wear of incisal edgesFlat smiling lineLoss of tips of canine
35Check Shade Against the Patients Face Check shade of existing dentureAsk if patient wants same shade or changeAllow patient to view shade against lip with mirrorObtain patient approval
36Patients 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.
37The anterior teeth from the lightest to the darkest Upper central incisorThe upper lateralThe lower central and lateralThe upper and lower canines are the darker.
391-Size of posterior denture teeth a-Length:This is determined by the amount of denture space available between the upper and lower ridges.
40b-WidthFrom distal of canine to the tuberosity in the maxillary denture, and to the retromolar periphery of the lower denture.The teeth with a narrower buccolingual width than the natural teeth are selected.
41Posterior Tooth Selection Buccolingual size can affect the tongue spacesmaller teeth if tongue space is limited
42Posterior 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 lower posterior teeth should not extend posterior to the mesial border of the retromolar pad.
432-Form of the occlusal surface (Mould or shape) Cusp angle :the angle made by the slope of the cusp with the cusp plane
44Cusp Height : The perpendicular distance between the tip of the cusp and its base plane
46Cusped Teeth (Anatomic teeth) have cusp angle Indicated when there is a well defined ridge and normal jaw relations.
47Advantages 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
48Disadvantages 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
49Flat or Inverted Cusped Teeth Have zero cusp angle with grooves to aid mastication
50Non-Anatomic Teeth (0°, Rational, Monoline, etc.) Jaw size discrepancies (Class III)Severe ridge resorptionPoorer esthetics, due to lack of cuspal inclines
51Indications of flat plane teeth 1-In class II and III jaw relations.2- patients with temporomandibular joint disorders.3-In case of atrophic alveolar ridge.4-In the presence of hyper mobile gingival tissues (flabby ridge).
52Disadvantages of flat plane teeth a) Reduced masticatory efficiency.b) Poor appearance.c) Food may become packed into the depression of teeth.d) It is very difficult to obtain balance..
533-shade (color) The same shade as the canines should normally be used one or two shades darker.
54Tooth materialArtificial teeth for complete denture are either acrylic teeth or porcelain teeth
55Denture Tooth Material Porcelain teeth less common nowAcrylic easier to set and adjust
56Comparison between acrylic and porcelain teeth 1-Hardness and abrasion resistance:Porcelain teeth are harder and more resistant to wear.
572-Aestheticsthe appearance of porcelain teeth had a better reputation than the acrylic teeth.The porcelain teeth will not have stains, while acrylic teeth can be stained
583-Retenion to denture base The bonding of porcelain teeth to the denture base is purely mechanical. This by pins on anterior teeth and holes in posteriorsRetention of acrylic teeth to denture base is chemical.
594-Thermal expansionThe coefficient of thermal expansion of porcelain is much lower than acrylic resin which my results in cracking of acrylic base.The coefficient thermal expansion of acrylic teeth is the same as acrylic denture base.
605-AdjustmentPorcelain is more difficult to grind and difficult to polishAcrylic can be ground and easily polished.
627-Impact strengthThe impact strength of acrylic teeth is greater than that of porcelain.So acrylics may be used in cases of close anterior occlusion.
638-In service Acrylic teeth transmit less force to the mucosa. On contact with the opposing teeth, acrylic teeth are less noisy. While With Porcelain teeth, clicking occurs on contact with the opposing teeth.
64Acrylic 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
65Denture Tooth Material AcrylicNew acrylics wear betterImproved translucency with layersMore resilient - Less breakageChemically bonds to baseQuieterEasier to set/adjustGum sticksPorcelainLess wearMore translucentBrittle - fracture easilyDon’t bond to base (stain, fall out)Difficult to set, adjust
66Porcelain teeth- Wear is clinically insignificant over a long period of time - No significant loss vertical dimension - 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.
67Acrylic 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
68The following facts are true for nearly all natural teeth: The neck of the tooth has a more pronounced color than the incisive edge.The incisive edge if not worn, is more translucent than the body of the tooth and is usually of a bluish shade (composed entirely of enamel)The upper central incisors are lightest teeth in the mouth followed by the laterals and canines. Posterior teeth are usually uniform in color.Teeth darken slightly with age.
69Advantages 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 ). 3. Non anatomic teeth exerts less horizontal or torquing forces, so they are used with flat ridge cases. 4. Centric record only is needed.