Prostho 1 Finals Part 3 (Dental Ceramics, Pontic Design)

Covers Dental Ceramics and Pontic Design: Part 1: https://knowt.com/flashcards/e0dd88cc-d968-44a3-86ce-2e310e1191fa?fbclid=IwAR2zDIi5XjHTgCtKHWEf0Ka3MDEN-h8aQyc_9zWPdEnh_mQUGdqIB1alsXg Part 2: https://knowt.com/flashcards/470c89f8-0fcc-4443-ad14-a070a6d313a3?fbclid=IwAR3ZJAzNdhlkA-likFiF9JDjTeo--myvNTuhghpK5_eaXo0uBe8P2A6sEbA

Dental Ceramics

Finely ground ceramic particles pigmented to match natural tooth colors for dental restorations.

High Fusing Porcelain

Porcelain with a fusing temperature of 1288-1371°C (2350-2500°F), used for denture teeth but not tooth restoration.

Medium Fusing Porcelain

Porcelain with a fusing temperature of 1093-1260°C (2000-2300°F), used for ceramic restorations like porcelain jacket crowns.

Low Fusing Porcelain

Porcelain with a fusing temperature of 871-1066°C (1600-1950°F), used for PFMs and metal-ceramic crowns.

Vitrification

Porcelain solidifying with a liquid structure instead of a crystalline one.

Glass Formers

Elements like oxygen, silicon, boron, and phosphorus forming stable bonds in the glass matrix of dental porcelains.

Opaque Porcelain

Used to conceal metal coping in dental restorations.

Pontic Design

Artificial teeth in fixed partial dentures designed to restore function, appearance, and hygiene.

Biologic Pontic Design

Focuses on tissue cleanliness, abutment access, and ridge pressure prevention for successful pontic design.

Mechanical Pontic Design

Emphasizes rigidity, strong connectors, and metal-ceramic frameworks for pontic durability.

Esthetic Pontic Design

Aims for a natural tooth appearance, emergence profile, and adequate porcelain space in pontic restorations.

Residual Ridge Assessment

Evaluation of ridge shape, height, width, and frenum attachments for pontic placement and appearance.

Mucosal Contact Pontic

A pontic design with a concave fitting surface overlapping the residual ridge, challenging for cleaning.

Modified Ridge Lap Pontic

Combines hygienic and esthetic features by overlapping the facial ridge while remaining clear on the lingual side.

Conical Pontic

Egg-shaped pontic design with a single contact point at the center of the residual ridge, easy to clean but not suitable for all ridges.

Ovate Pontic

Esthetically appealing design with a convex tissue surface resembling a tooth emerging from the gingiva.

No Mucosal Contact Pontic

Sanitary design allowing easy cleaning and plaque control, with variations like modified sanitary pontic for improved stress distribution.

Types of layers of porcelain

• Opaque porcelain

• Body porcelain

• Incisal porcelain

Paradigm of Successful Pontic Design

Biologic

Mechanical

Esthetics

Feldspar

Part of Compositon of Dental Porcelains.

(85%)

Provides a glassy phase and serves as matrix for the quartz

Quartz

Part of Compositon of Dental Porcelains

(12-22%)

Strengthener

Kaolin

Part of Compositon of Dental Porcelains

(4%)

hydrated aluminum silicate (that acts as a binder to increase modability of unfired porcelain)

Oxides incorporated in silicon-oxygen matrix

1. Potassium

2. Sodium

3. Calcium

4. Aluminum

5. Boric oxide

Fluxes

Lowers the softening temp of glass by reducing the amount of cross linking between the oxygen and glass forming elements.

Types of layers of porcelain

1. Opaque porcelain

2. Body porcelain

3. Incisal porcelain

Special types of porcelain

Color Frits
Stain
Overglazed / applied glazes

Color frits

1. Added to the dental porcelain to obtain the various shades needed to simulate a natural tooth. 

2. These coloring pigments are produced by fusing metallic oxides together with fine glass and feldspar and then regrinding them to a powder

Stain

employed as surface colorants or used to replicate enamel checklines, hypocalcification areas or other tooth defects in the body of porcelain restoration

Overglazed or applied glazes

- ceramic powders that are painted on the surface of the porcelain restoration which is first at a maturing temperature lower than that of the restoration to produce a transparent glassy layer on the surface.

Classification of residual ridge deformities according to Siebert

1. Class 1 defect

2. Class 2 defect

3. Class 3 defect

Class I defect

faciolingual loss of tissue width with normal ridge height

Class II defect

loss of ridge height with normal ridge width

Class III defect

combination in loss of both dimension

Pretreatment Assessment

1. Pontic space

2. Residual Ridge Contour

Pontic space

The function of an FPD is to prevent tilting or drifting of the adjacent teeth into the edentulous space. 

1. If such movement has already occurred, creating an acceptable appearance without the benefit of orthodontic repositioning is difficult.

2. Modification of abutments with complete coverage retainers is the only solution.

Residual ridge contour

1. Edentulous ridge and topography should be evaluated for the following:

   1. Shape of the ridge - smooth, regular of attached gingiva which facilitates maintenance of plaque free environment

   2. Height and width of the ridge - allow placement of a pontic that appears to emerge from the ridge and mimics the appearance of neighboring teeth

Frenum attachments

FPD must be free of [BLANK] and adequate facial height to sustain the appearance of interdental papillae

Pontic design classification

1. Mucosal contact

   1. Ridge lap

   2. Modified ridge lap

   3. Ovate

   4. Conical

2. No mucosal contact

   1. Sanitary (hygienic)

   2. Modified sanitary (hygienic)

Sanitary or hygenic pontic

• The primary design features of the sanitary pontic allows easy cleaning because the tissue surface remains clear of the residual ridge

• This hygienic design permits easy plaque control by allowing gauze strips and other cleaning devices to passed under the shoe shine fashion.

• Its' disadvantage include entrapment of food particles which may lead to tongue habits that may annoy the patient

• Least tooth like design of all pontic

Modified sanitary pontic

• Its gingival portion is shaped like an archway between the retainers. 

  • This geometry permits increased connector size while decreasing the stress concentrated in the pontic and connector.

• It is less susceptible to tissue proliferation that can occur when a pontic is too close to the resıdual ridge