• ovate pontic is a round-end design currently in use where esthetics is a primary concern.
• It is set into a concavity of the ridge
• the concavity can be created by placement of a provisional fixed partial denture with the pontic extendint one-quarter way into the socket immeditely after extraction of the tooth or it can be crated sugically at some later time.
• it gives an apearance that it is growing from the ridge. 

non: plaster, imp cmpd (guttapercha, dental imp cmpds, waxes), zinc oxide eugenol

elastic:  hydrocollloids (rev: agar, irrev: alginate), non aqueous isomers (silicones, polyester, polisulfides)

1. situation
2. area
3. place
4. working phase
5. type of imp material
6. number of imp materials' viscosity
7. techniques

anatomical: records tissue shape without distortion

functional: impression of supporting structures in their functional form

• total
• partial

• upper (lower), maxillary (mandibular) impression:  an impression of maxillary jaw and related tissues and dental structures.
• antagonist

• 1-step
• 2-step

types of impression according to type of imp mat:

alginate

silicone

polyesters

• Hydrophobic: esp. in v. early stage
• thixotropic
• adapts precisely to the surface (low surf tention)
• reproduces precise details
• dimentionally stable

• monophase
• putty wash

• single/ mono phase
• 2-step, putty wash
• 1-step, putty wash, double mix or sandwich impression

single/ mono phase imp technique:

(when is it recommended, and list the steps)

• recommended for complete dentures, antagonists, partial fixed dentures (inlay, onlay, crn, bridge)

1. try tray in the mouth
2. apply tray adhesive to surf of tray
3. isolate abutment th, and place gingival displacement cord in the sulcus
4. imp mat. mixing in separate pads, and taking it to the tray
5. remove displacement cord and gently dry the prep with compressed air
6. set the tray, must remain immobile while polymerizing
7. cleaning
8. evaluation
9. disinfection: glutaldehyde 2% (silicone, polisulfide), chlorine cmpd 0.1- 6% (hydrocolloide, silicone, polisulfide)

2-step, putty-wash technique:

(recommendation and properties)

• removable partial dentures, and fixed partial dentures (inlay, only, crn, bridge)

• wash and tray material are of different viscotisities: wash is light bodied (type 3; ISO 4823), and tray is mostly putty (type 0; ISO 4823), But Heavy body can be used also. 

1. try tray
2. apply adhesive to tray
3. isolate abutment th and place displacement cord
4. mix heavy body imp mat, and put it into the tray
5. set the tray: must remain immobile etc.
6. clean
7. evaluate
8. remove undercut areas
9. remove displacement cord, and gently dry prep with compressed air
10. on separate pads, light body imp mat mixing, and taking into impression
11. set the tray
12. clean
13. evaluate
14. disinfection

wash material: light body (type 3)

tray material: heavy body (type 1), medium or putty

heavy and light bodies are place onto the tray together and impressiong is made once.  Therefore, there's a chance of th penetrating the light body completley and entering heavy body material.  maybe produce inaccurate impression.

displacement of gingival tissues:

(def. and steps)

= deflection of marginal gingiva away from tooth

mechanical/ chemical/ electrosurgical

1. isolate prep'd th with cotton rolls
2. cut a length of cord sufficient to encircle the th.
3. dip the cord in astringent solution
4. loop cord around th and gently push it into the sulcus. 

15.5% Fe2(SO4)3

20% AlCl3

1. solid cast with individual (removable) die
2. pindex
3. di-lok
4. DVA model system
5. Zeiser

• impression scanners
• intraoral scanners (digital impressions)
• model-cast scanners

diode laser is used to trough around the tooth in preparation for taking optical impression.

• wax-up printer
• laser sinterin
• CAD-CAM

• Rapid Prototyping or Rapid Manufacturing.
• aka. additive or layered manufacuring.
• enables undercuts, internal voids, or complex structures
• can reduce or eliminate assembly

1. produce accurate copy
2. prevent shrinkage
3. must be free of bubbles
4. proper surface
5. high detailed morphology
6. give possibility to accss from every direction

study model

separate die

removable die

• can remove the prep'd tooth from the model
• has accurate margin definition around the tooth
• inaccurate after several use
• gingiva is not visible at the margin
• several pin systems

1. history taking, clinical exmination
2. diagnostic casts, and related procedures
3. treatment planning
4. mouth prep'n
5. laboratory procedures
6. cementation
7. postoperative care

• plastic mat
• cast metal
• metal-ceramic
• resin veenered
• fiber-reinforced
• all-ceramic
• fixed partial dentures
• implant supported prosthesis
• removable partial dentures
• complete dentures

• crown-root ratio
• root configuration
• periodontal ligament area

removable partial denture

tooth supported fixed partial denture

implant supported fixed partial denture

1. age
2. number and place of abutments
3. periodontitis
4. in the highest degree of bone absence
5. supraclusion of opposing tooth
6. general aspects (radiation therapy, terminal illness)

1. # of abutments (abutment pontic ratio)
2. connection between the retainer and abutments
3. the faciolingual movement of the tooth
4. materials

• biological: prevent damage during prep'n (adj th, soft tissue, pulp).  causes of injury can be by temperature, chemical or bacterial action.  Conserve tooth structure
• mechanical: Resistance and retention (magnitude and direction of dislodging forces, geomety of the th prep'n physical properties of luting agent)  Deformation (alloy selection, adequate th reduction, margin design)
• Esthetic:  Metal ceramic rest'n (facial, incisal, proximal reductin, labial margin placement), Partial-coverage restoration (proximal and facial margin) 

biol:  pulp protection, periodontal health, occlusal compatibility, and tooth position

prevention of enamel fracture

mech: resist functional load and removal forces, and maintain interabutment alignment

esthetic: easily contourable, color compatible, translucency, and color stability

external surface form:  custum or preformed

tissue surface form:  indirect, direct, and indirect-direct procedure

material: PMMA, UDMA, Bis-GMA

advant: stability of chemical structure, biocompatibility, high resistance to wear and distorsion

disadv:  brittle

denture th.

porcelain enamels used with metals

all-ceramic crowns etc

1. sintering (condensation and sintering)
2. castable ceramics
3. pressed-glass ceramics
4. milled ceramic/ CAD-CAM

• cement or luting agent is a viscous material placed between the tooth surf and a fixed prosthesis that hardens through chemical reactions to firmly attach the prosthesis to tooth structure (ex. zinc phosphate, polycarboxylate, glass ionomer)
• traditionally, crown is held in place by luting cement that fills minor irregularities along the crn and dentine surfaces.

• prep'n trauma
• microbial exposure
• dessication
• chemical exposure
• thermal exposure

• lowest on the occ'll surf
• high at the pulp horns
• highest at axial surf's
• there are about 3-4 million dentine tubuli/ cm2 on the surf of a prepared molar th
• "smear layer" : mineral deposits, macromolecules precipitations. 

• diameter= 0.2- 1.0 micrometer
• functional diameter= ~0.2 micrometer
• transport mech: convection, diffusion
• changes of pressure of pulp tissue-> barroreceptor stimulation-> pain

temporary removable dentures:  traditionally made RPD and full dentures, immediate dentures

provisional fixed dentures:  custom made and prefabricated FPD's

• a missing proximal contact allows tooth migration:  PR needs to ensure positional stability
• PR protects tooth structure

• excessive overcontouring of PR may jeopardize the periodontal health:  pressure ischemia and poor access for plaque removal promote gingivitis
• should have a good marginal fit, proper contour, and a smooth surface finish

polymethyl-metacrylate (PMMA)

polyethyl-metacrylate (PEM)

polyvinylethyl-metacrylate (PVM)

Bis-acryl composite

VLC urethane- dimetacrylate (UDMA)

stainless steel

NiCr steel

polycarbonate

cellulose acetate

aluminum