ProsthoMat Flashcards
Eugenol effect?
eugenol is extracted from?
obtundent effect / relief
from oil of cloves
more stable technique to soften the impression compound
dry heat - best for the material
water bath - more convenient, best for patient and dentist
elastic impression material with the least tear strength
Hydrocolloids
(reversible > irrev)
ability of material to change its form based on temperature
Hysteresis - only seen in reversible hydrocolloids (agar)
a. Liquefaction - gel to sol (boiling)
b. gelation - sol to gel
*imbibition - absorbs water
syneresis - releases water
components of reversible hydrocolloids? principal component
water (85%) - principal
agar (15%) (sometimes w/ borax)
effect of borax to dental materials
+gypsum = retarder
+agar = hardener
least dimensionally stable impression material, shortest setting time and least expensive
irreversible hydrocolloids (alginate)
components of irreversible hydrocolloids? principal component? major component?
sodium alginate/potassium alginate - reactor (major)
calcium sulfate - reactor
diatomaceous earth/silica - filler (50~% principal component)
sodium phosphate - retarder
ways to decrease setting time of alginate
increase water temp
mix rapidly
decrease water to powder ratio (thicker consistency)
1st elastomer (3 names)
polysulfide, mercaptan, thiokol
Composition of polysulfide
BASE - white
liquid poly sulfide polymer 80-85%
fillers - carbonate, silica, titanium dioxide, zinc sulfate, copper
ACCELERATOR - brown/gray
lead dioxide - 60-68% (an alternative will be hydroperoxide)
dibutyl phthalate - 30-35%
sulfur - 3%
others - 2%
lead dioxide causes stain and foul odor
characteristics of polysulfide
longest setting time (12 mins) foul odor in not usually tolerated
messy to work with (viscous and sticky)
stains and emits foul odor (lead dioxide)
greatest tear strength
hydrophobic
least dimensionally stable among the elastomers
condensation silicones / conventional silicones
Characteristics of condensation silicone
has a byproduct - ethyl alcohol –> can cause shrinkage
pleasant odor
hydrophobic
least dimensionally stable among the elastomers
composition of condensation silicone
BASE
polydimethyl siloxane
colloidal silica / metal oxide filler - 35 -75 %
ACCELERATOR
orthoethyl silicate - cross linking agent
stannous octoate - catalyst
composition of addition silicone (PVS)
BASE
poly (methyl hydrogen siloxane)
fillers
prepolymers
ACCELERATOR
divinyl polysiloxane
platinum salt - catalyst (chloroplatinic acid)
palladium - hydrogen absorber
retarders
fillers
characteristics of addition silicone
pleasant odor
excellent reproduction details
most dimensionally stable (up to 2 weeks)
hydrophobic
emits hydrogen gas
avoid latex gloves (contains sulfur) –> retards setting
plasticizer of polyether
glycoether or phthalate
cross linking agent of polyether? condensation silicone?
P - aromatic sulfonate ester
CS - orthoethyl silicate
characteristics of polyether
extremely stiff
very difficult to remove from mouth
hydrophilic
best compatibility with stone
very expensive
rank dimensional stability of elastomers
Addition silicone > polyether > polysulfide > condensation silicone
types of gypsum
type 1 - impression plaster
type 2 - dental plasters
type 3 - dental stone
type 4 - improved stone (die stone)
type 5 - high strength dental stone, high expansion
how is gypsum manufactured?
heating gypsum loses part of its water
calcium sulfate dihydrate –> calcium sulfate hemihydrate
calcination
differentiate the two hemihydrates
plaster - open kettle >100C - irregular particles, porous
stone - closed kettle or steamed under pressure > 100C - regular particles (prismatic), lesser porosity (denser)
How to create improved type of stones
gypsum is calcined by boiling it in 30% calcium chloride –> very dense , lesser pores
gypsum accelerators
gypsum, sodium sulfate, potassium sulfate, sodium chloride (2%)
gypsum retarders
HIGH CONC of sodium chlodride (>2%) and sodium sulphate, borax acetates, citrates, tartrates, blood
increases the setting expansion of the gypsum
adding NaCl and ground gypsum
allowing the gypsum product to set while it is in contact with water
hygroscopic expansion
placing gypsum investment mould in a furnace at a temp lower than 700C
thermal expansion
linear expansion of gypsum during setting due to outward thrust of the growing crystals
setting expansion
allows investment material to expand
casting ring liner
a channel where metal or plastic can flow towards a mold
sprue
*sprue former - wax, plastic or metal to possible create a sprue
attaching a sprue former into wax pattern and mounting it ina sprue base/ crucible former
Spruing
process of enveloping or covering an object in order to create a mold
investing
a ceramic material suitable for forming a mould into which a metal or alloy is cast. Components??
Investment material
1. binder (gypsum bonded -for gold alloys and other low fusing, phosphate bonded, silica-bonded)
2. refractory material - resists melting of the investmetn
flushing out of wax pattern and creating a mould. Place in a burn-out furnace
Burn-out
process of forming an object in a mould
casting
type of sprue that can cause casting porosity? incomplete casting?
casting porosity - short sprue
incomplete casting - long sprue
zone of the flame used in casting dental alloys
reducing zone (torch flame)
Common natural waxes used to create dental waxes
paraffin wax, beeswax, carnauba wax
types of waxes and their uses
- pattern wax - inlay, onlay, crowns, rpd wax
- processing wax - boxing wax, sticky wax, utility wax
- corrective wax - bite wax
Malleability vs ductility
malleability - ability to be hammered into thin sheets
ductility - can be shaped without fracturing
noble metal that corrodes in the oral cavity
silver
it has the highest CTE/COTE among all dental materials
waxes
best way to prevent warpage of wax pattern
invest immediately; if unable, refrigerate –> then cool to room them before investing
Noble metals are used because they resist corrosion in the mouth. examples?
gold, platinum, palladium
others: rhodium, ruthenium, iridium, osmium, silver
most malleable, most ductile, best restorative material, and has the closest properties to tooth
Gold
most common anti-flux
soft graphite pencil
*to restrict flow of solder
ADA classificiation of dental alloys according to nobility
- high noble metal alloys / Precious metal (>40% gold, >60% noble metal)
- noble metal alloys (semi precious
(>25% noble metal) - predominantly base metal / Non-precious
(<25% noble metal)
Classification of dental alloys according to strength and percentage elongation
type 1 - soft : small inlays, class III, V
type 2 - medium : large inlays, onlays
type 3 - hard : crowns & bridges
type 4 - extra hard : denture framework
resistance to breaking under compression? under tension? under horizontal forces?
compressive strength
tensile strength
shear strength
Stress value just above the proportion limit which there is permanent deformation
(Dmf: most important, resistance to permanent deformation)
yield strength
*ultimate strength - maximum stress before fracturing
high modulus of elasticity means
material is rigid/stiff
important for wear characteristics and finishing
(UP: resistance to indentation)
hardness
change in length per 1 degree celsius change in temp
CTE
fusion temp for soldering
100 - 150 degree F
optimal space for solder
0.25mm
function of flux
improve flow of solder and dissolves oxides, prevent contamination
components of conventional dental porcelain
feldspar - principal component
quartz - refractory skeleton that provides strength and hardness durinng firing
Kaolin - binder
property that makes a material brittle
high compressive strength, low plastic deformation
three dimensions of color
Hue - color
chroma - saturation of hue
value - lightness / blackness / whiteness
value is the most important dimension in dental restorations
best light source
sunlight / natural light (10am to 2pm)
phenomenon in which 2 objects appear to be the same color in a specific light source and appears different in another light source
metamerism
oldest luting cement
Zinc phosphate / Zn oxyphosphate / crown and bridge cement (ADA 8)
application of Zinc phosphate (ADA 8)
luting of restorations
high strength base
temporary restoration
luting of orthodontic bands and brackets
characteristics of zinc phosphate cements (ADA 8)
mechanical retention (NO CHEMICAL BOND TO TOOTH)
very acidic when freshly mixed (pH 3.5)
rapid setting time
ADA spec of amalgam, inlay wax, gold
amalgam #1
inlay wax #4
gold #5
least irritating of all dental cements
zinc oxide eugenol (ADA 30)
solubility of set cement is highest among the cements
zinc oxide eugenol (ADA 30)
components of MODIFIED ZOE
zinc oxide
eugenol
ethoxy benzoic acid (EBA)
Classification of ZOE (ADA 30)
type 1 - temporary cement
type 2 - permanent cement
type 3 - temporary filling and thermal insulation (IRM)
type 4 - cavity liners
characteristics of zinc oxide eugenol cements (ADA 30)
do not adhere well to enamel and dentin
low strength
highest solubility of set cement
biocompatible (obtundent effect)
excellent thermal insulator
bacteriostatic
inhibits polymerization of resin
seals dentinal tubules and inhibit resin setting
cavity varnish
liquid of zinc polycarboxylate (ADA 61)
polyacrylic acid or copolymer of acrylic acid
application of zinc polycarboxylate (ADA 61)
primarily as a luting cement
base and liners
1st cement discovered that chemically bonds to tooth structure
zinc polycarboxylate (ADA 61)
characteristics of zinc polycarboxylate (ADA 61)
adheres to tooth structure
mild pulpal response
acidic (3 - 4)
faster setting than zinc phosphate
components of silicate cements (ADA 9)
powder -silica
liq - phosphoric acid
application of silicate cements (ADA 9)
esthetic resto of anterior teeth
intermediate resto in px with HIGH CARIES rate
1st tooth colored cement and 1st fluoride releasing cement
silicate cements (ADA 9)
has the lowest CTE among any restorative material
silicate cements (ADA 9)
most acidic cement when freshly mixed
silicate cements (ADA 9)
most soluble cement within the first 24 - 48 hrs
silicate cements (ADA 9)
powder composition of GIC / aluminosilicate cement
silica - principal comp
alumina
alumina fluoride
calcium fluoride
sodium fluoride
aluminum phosphate
liquid composition of GIC / aluminosilicate cement
polyacrylic acid - principal comp
itaconic acid
maleic acid
tricarballylic acid
tartaric acid
water
least soluble cement
GIC
*technique sensitive
*sensitive to air and water
GIC classifications
type 1 - luting
2 - resto
3 - liners and base
4 - fissure sealants
5 - orthodontic cement
6 - core build up
7 - fluoride release
8 - ART
9 - pediatric purpose
Classes of articulators
1 - simple hinge - vertical motion
2 - standard mean value - horizontal and vertical but not oriented to TMJ
3 - semi-adjustable - stimulates condylar pathways (protrusion, lateral excursion)
4 - fully adjustable - 3 dimensional dynamic registration
arcon vs non-arcon artic
articulating condyle
-upper member: mech fossa
-lower member: mech condyle
non-arcon
-upper member: mech condyle
-lower member: mech fossa
Mx ang gumagalaw
Facebow records what?
Patients maxilla/hinge axis relationship.
Mx arch to an anatomic reference
Arbitrary vs kinematic
AVE Condylar angle
30
Used to approximate the condylar inclination
Protrusive record
-produces christensens phenomenon
Used to determine the bennett angle
Lateral excursion record
Ave of 15 degrees formed by the condyle on the balancing side
Used as reference to establish occlusal plane
Interpupillary line
Camper’s line (ala to tragus, foxplane)
Differentiate the compensating curves
Curve of spee - anteroposterior curve - md canine to buccal cusp of posterior teeth (steeper condylar inclination, steeper spee)
Curve of wilson - mediolateral curve
Monson curve - ideal curve for occlusion. Combination. Post teeth and incisal of anteriors are aligned within an 8 inches sphere with glabella as center
Space in between mx and md when the mandible is at rest
Freeway space = VDR - VDO
2-4mm average
Aka interocclusal distance
Maxillomandibular relationship in which the condyle articulates with the thinnest avascular portion of disk with the complex in the most superior and anterior position against artitular eminence
Centric relation -purely rotational movement, no bearing ang tooth or VD
-old der: most superior posterior position of condyle, ligament-related?
Complete intercuspation of opposing teeth independent of condylar position
Maximum intercuspal position
Occlusion of teeth when md is in CR
Centric occlusion
Position of the md at physiologic rest
Rest position - muscle guided position
Differentiate inflammatory papillary hyperplasia and inflammatory fibrous hyperplasia
Papillary - located at the palatal tissue, ill fitting denture kept at night, tx. Reconstruct denture/removal
Fibrous -epulis, ill fitting denture
Types of patient
- Philosophical - accepts dentist judgement and instruction
- Exacting - methodical and demanding
- Indifferent - doest care
- Hysterical - emotionally unfit to wear dentures
Direction of ridge resorption
Mx - superior and posterior or superior and inward (constrict)
Md - inferior and anterior or inferior and outward (widen)
What is the vibrating line
Imaginary line demarcating the movable and immovable tissues of soft palate
Posterior border of mx cd that puts pressure on the displaceable tissue near the junction of hard and soft palate
Posterior palatal seal (denture base)
Seen in the cast as post dam
When to reline immediate denture
6months and 12 months (some sources: 5 and 10)
Burning sensation in md ridge may be due to? On the palatal area?
Pressure on mental foramen - md ridge
Pressure on incisive foramen - palatal area
Clicking of denture teeth may be due to?
Excessive VDO, porcelain teeth, habit of patient
Causes of cheek biting
Not enough horizontal overlap of posterior teeth, insufficient VDO
What is kelly syndrome
Combination syndrome
- completely edentulous mx
- class I RPD
Results to mx anterior segment resorption
mandibular major connectors
Lingual bar - 3-4 away from gingival margin, 4mm thick
Lingual plate - kennedy blanket - less than 7 functional depth, high frenal attachment, extensive class I case
Kennedy bar/continuous bar/ double lingual bar
Labial bar - severe inclination
Swing lock - major connector on both lingual and labial can be also called as ‘labial bar’
Maxillary major connectors
Palatal strap - >=8mm thickness
APPC - most commonly used
Palatal plate - severe class I
U-shaped/ horse-shoe - least desirable, least rigid type
Location of minor connectors
Embrasure
Components and dimensions of direct retainer
- Retentive component - terminal/flexible 3rd - 0.5mm to 1mm; gingival 3rd
Semi-rigid - 1.5mm
Rigid - 2mm - Reciprocal component - junction of gingival 3rd and mid 3rd or above the survey line
- Rest
Occlusal - spoon shape/rounded triangular - 1/3 BL, 1/3 MD, 1.5 deep (molars)
Cingulum - MD: 3mm, LL: 2mm, depth 1.5mm
Incisal - MD: less than 2.5 mm, depth 1.5mm
Minimum encirclement of retentive clasp assembly
More than 180
Ante’s law
Surface area of the roots of abutment teeth should equal or exceed the surface area of the roots of the teeth to be replaced
Biologic width
2.04mm
JE : 0.97mm
CT: 1.07mm
Best? Minimum? Optimum crown root ratio?
Best: 1:2
Minimum: 1:1
Optimum: 2:3
Preserved surface for 7/8 crowns
Mesiobuccal
Mx premolars and 1st molars
Retraction cords
0.8% epinephrine causes vasoconstriction
Potassium aluminum sulfate
Aluminum chloride - if greater than 10% tissue destruction
40% zinc chloride - tissue necrosis
Ferric sulfate - good hemostatic agent, discolors tissue temporarily
Pontics
Ridge lap
Modified ridge lap
Sanitary (fish belly, ferrel)
Bullet/conical
Ovate
Process of Changing the rubber base product into final rubber like material
Curing or vulcanization
Mercaptan is a compound containing
Sulfide group
Process of growing or lengthening of polymer bec of lead peroxide in the presence of sulfur
Polymerization (liq to solid)
Optimum thickness of material between the teeth and side of tray
2-3mm
Reactor used to polymerize silicone
Organic tin / tin octoate
Reactor in alginates
Calcium sulfate
*alginate + calcium sulfate = calcium alginate
Oxidizing agents used in the polymerization of polysulfide impression material
Hydroperoxide
Lead peroxide
Zinc polycarboxylate cement reaction
Chelation reaction
