ALL CERAMIC RESTORATIONS

1

• ALL CERAMIC RESTORATIONS

dr shabeel p n
2
Complete ceramic crown

• Should have relatively even thickness
  circumferentially
• About 1 to 1.5mm thickness needed to create
  esthetically pleasing restoration

3

• Advantage
• Superior esthetic
• Excellent translucency
• Good tissue response
• Conservative reduction of facial surface
• Appearance of restoration influenced by color of
  luting agent

• Disadvantage
• Reduced strength of restoration
• Significant tooth reduction
• Difficulty in obtaining well fitting margin
• Not effective as retainer for fixed prosthesis
• Wear observed on functional surface of natural
  tooth

4

• Indication
• Areas with high esthetic requirement
• Tooth should be relatively intact with sufficient
  coronal structure to support the restoration
  particularly incisal area
• Centric contact must be in an area where
  porcelain is supported by tooth structure

• contraindication
• When more concervative restoration can be used
• If occlusal load is unfavourable

Contra
5
Preparation

• Armamentarium
• Narrow round tipped tapered diamond
• Football shaped diamond
• Finishing stones and carbide
• Mirrors and periodontal probe
• Explorer chisels hatchets
• handpiece

6
(No Transcript)
7
Facial reduction

• Placing depth orientation groove
• One depth groove in middle of facial wall and one
  each in the mesiofacial and distofacial
  trancitional line angle
• Depth is 0.8mm to allow finishing
• Cervical component parallel to path of placement
  and incisal component parallel to original
  contour of the tooth
• Reduction is performed on half at a time

8
(No Transcript)
9
Lingual reduction

• Football shaped diamond
• Selected path of placement has been transferred
  from cervical wall of facial preparation
• Place depth groove in middle of cingulum wall
• Margin should follow free gingival crest
• Should not extent too far subgingivally

10
Chamfer preparation and finishing

• 1mm wide smooth continuous and free of any
  irregularity
• A 90 degee cavosurface angle is optimal
• Objective is to direct stress parallel to path of
  placement
• A sloping shoulder result unfavourable loading of
  porcelain
• Round any remaining sharp line angle to prevent
  wedging action

11
(No Transcript)
12
Strengthening mechanism of dental ceramic

• Fabrication defect
• Created during processing
• Consist of voids porosity microcrack
• Surface crack
• Induced by machining
• Flaw effectively determines the fracture
  resistance of restoration

13

• Crystalline reinforcement
• Introduction of high proportion of crystalline
  phase
• A crystalline phase with greater thermal
  expansion coefficient produce tangential
  compressive stress near crystal matrix interphase
• Such tangential stress tends to divert the crack
  around particle

14

• Chemical strengthening
• Relies on the exchange of small alkali ions for
  larger ion bellow the strain point of ceramic
• This techniqe is diffusion driven and its kinetic
  are limited by time temperature and ionic radius
  of exchanging ions

15

• Stress induced transformation
• Zirconia is monoclinic at room temperature and
  tetragonal at 1170 degree
• Stress triggers transformation from tetragonal to
  monoclinic zirconia
• This leads to strengthening as a result of
  increase in grain volume in the vicinity of the
  crack up

16

• Glazing
• Addition of surface glaze
• The principle is formation of low expansion
  surface layer at a high temperature
• Self glazing consist of an additional firing in
  air after original firing without application of
  a low expansion glaze

17

• Prevention of stress corrosion
• Baked on metal foil may reduce fracture incidence
  by reducing moisture exposure to internal surface
  of ceramic
• Coating are used also used to reduce stress
  corrosion of glass ceramic

18
(No Transcript)
19
Selection of all ceramic system

• Fracture resistance
• Promising result if the restoration are confined
  to lower stress anterior teeth
• Esthetic
• A knowledge of available ceramic system is needed
• Marginal adaptation of system is important
• Translucency of adjacent teeth and discoloration
  must considered

20

• A more opaque high strength core ceramic system
  like inceram or procera are not good choice for
  highly translucent teeth
• Abrasiveness
• Potential for abration of opposing tooth
  particularly in patient with parafunctional habit
• Low abration material should be concidered

21
All ceramic partial fixed prosthesis

• Inceram alumina for anterior fdp
• Lithium disilicate heatpressed ceramic empress 2
  cad cam procera system are also suitable for
  anterior fdp

22
All ceramic foundation restoration

• All ceramic is used as foundation restoration
  for endodontically treated teeth to overcome
  esthetic problem associated with metal post and
  core system

23
Resin bonded ceramic

• Performance of all ceramic restoration has been
  enhanced by use of resin bonding

24

• Half moon fracture of crown is common form of
  failure it occure in
• Teeth with edge to edge occlusion
• When opposing tooth occlude cervical fifth of
  lingual surface
• Teeth with short crown
• Teeth with overshortened preparation