OPERATIVE DENTISTRY: Recent Episodes
Dr.Mayakha Mariam
AMALGAM COMPOSITION
Silver, tin, copper, mercury, zinc, palladium, indium
MERCURY
- Spherical cut – 40-45% – requires less mercury, small surfaces are easier to wet
- Lathe cut – 45%-50% - requires more mercury, more difficult to wet
SILVER ― 40-70% or 65% content
- Increases strength
- Increases expansion
TIN – 25-27%
- Opp to silver
- decreases strength
- decreses expansion
- increases setting time
GAMMA PHASES
Alloy containing mercury
Ag-Sn + Hg ⟶ AgHg + SnHg
Silver Tin + Mercury ⟶ Silver Mercury + Tin Mercury
४ γ1 γ2
(STRONGEST PHASE) (ABUNDANT PHASE) (WEAKEST PHASE)
γ2 - gamma 2 phase - SnHg - Tin Mercury
➢ Disadvantage - Brittle and Corrodes
➢ Advantage - Self Sealing
COPPER – 6%, 13%
Ag-Sn + Cu + Hg ⟶ AgHg + CuSn
४ γ1 eta η
To get eta phase - need 13% Copper ie. high copper amalgam
Q. The copper ratio that eliminates gamma phase 2 = 13 %.
ZINC – 1%
o In Factory, Silver and Tin, they may form oxide
o ∴ they add Zinc (used as oxide scavenger)
o Provides better clinical performance, less marginal breakdown.
o But, In restoration, zinc if contaminated by moisture, it will cause delayed expansionー seen 3-4 days post restoration ー due to release of hydrogen gas.
o Moisture contamination of Zn can be caused during
aー during trituration.
b ー during restoration.
PROPERTIES OF AMALGAM RESTORATION
Trituration
o The longer the trituration the smaller the setting expansion- shiny and wet appearance, strength will be maximal, and will have longer lasting luster after carving
o Inadequate trituration will have poor strength and rough surface, will cause corrosion more
o Trituration Time – 45-60 seconds
P/L ratio
o 1:1 by volume (EamesTechnique)
o 50% by weight
Working/Setting Time ー 3-4 minutes
Q. The maximum time elapsed before condensation of amalgam - 3 min
Condensing Force ー 3-4 lbs
Precarving Burnishing
a) to remove excess mercury
b) to condense and adapt to lateral walls*
Amalgam Cry / Silver Ringing Sound ー Setting Indication
Polishing ー After 24 hours* ー In the presence of water.
COMPLICATIONS IN AMALGAM
- MICROLEAKAGE ー sensitivity
● Prevention ー varnish prior to
● Most common problem.
● Causes
○ Not enough bulk restored
○ Lack of adequate condensation
○ Improper manipulation
○ Overcarving bonded
- ISTHMUS FRACTURE
● Major cause is shallow preparation / inadequate depth of cavity.*
● Other reasons ー too wide cavity preparation, sharp ‘axiopulpal line angle’. So bevel this axiopulpal line angle
● If asked specifically about primary tooth isthmus # - shallow preparation
● If asked specifically about permanent tooth isthmus fracture – sharp axiopulpal line angle .
Q. The most common immediate ttt. Reported for fractured teeth was 25%.
-
AMALGAM BLUEING (TOOTH)
● Seepage of amalgam contents upto DEJ causing blue discolouration.
● Management ー prior application of varnish. -
AMALGAM TATTOO (MUCOSA)
● Seepage of amalgam into the mucus membrane.
● Restoration, also retrograde amalgam restoration after apicoectomy.
● No treatment required.
Gingival discolouration
A. Bismuth in blood - Blue-black colour
B. Mercury in blood - black
C. Lead in blood – red / reddish blue.
- PAIN
● Within 48 hours
➔ Deep cavity ー patients come with sensitivity to hot and cold food.
➔ Pulp exposed.
➔ Class 2 cases ー pulpal horns exposure.
● Supra occlusion / High point / Defective Occlusion
➔ Within 1 week.
➔ TOP +ve
➔ Sensitivity to hot and cold food ーdue to detachment of CEJ from gums ー thus exposing
dentin ∴ Sensitivity.
● If only sensitivity
➔ Dentine cause and not high point
- Overhanging Restoration
➔ Symptoms ー irritation/ bleeding to interdental papilla.
➔ Happens due to improper or lack of matrix usage
➔ Instrument used to remove.- hoe
➔ It tears the gingiva leading to attachment loss
➔ It can stimulate inflammatory reaction directly
➔ It provides ideal location for plaque accumulation
- Galvanic shock
➔ Patient shows pain.
➔ Dissimilar metal.
➔ Amalgam vs Gold, ceramic
➔ RX Plan ー no RX required if no galvanic shock.
➔ Change restoration if pain is seen in the one
- Galvanic shock
➔ Patient shows pain.
➔ Dissimilar metal.
➔ Amalgam vs Gold, ceramic
➔ RX Plan ー no RX required if no galvanic shock.
➔ Change restoration if pain is seen in the one done recently or varnish over restoration.
- Delayed Expansion
➔ Caused due to insufficient trituration & condensation
➔ Also moisture contamination during either trituration / condensation – it’s the principle cause of amalgam failure.
➔ Careful of moisture contamination.
➔ Zn + H2O = release of hydrogen gas
➔ No particular time period.
➔ Cracks can be seen.
➔ RX ー change restoration.
- Mercury Toxicity
➔ Daily wear of amalgam seen : 1-3 μgs (microgram)
➔ Mercury threshold ー 50 μgs or 0.5 mg.
➔ Amalgam waste in special container with fixer solution or sulphide solution - even for extracted tooth containing amalgam.
RESTORATION FEATURES
Ideal amount of dentine between amalgam & pulp – 2mm
Amalgam average life span (when pt asks) ー15- 20 years or 2 decades
For amalgam Restoration of weakened cusp you should reduce cusp by 2mm on a flat base for more resistance.
Amalgam shows decreased microleakage with age
It is least technique sensitive of all the current cases
The base cement for amalgam should have – high modulus of elasticity
Scale to measure marginal detoriation / leakage / fracture in amalgam – Mahler scale
INITIAL TOOTH PREPARATION:
OUTLINE FORM
Definition – Extension to sound tooth structure at initial depth
1) Include all caries part
2) Place margins on sound tooth structure
3) Remove any caries undermined enamel
4) ideal cavity depth is 0.2-0.75 mm below DEJ / into dentin – floor should end in dentin.
5) Amalgam depth should be 1.5 – 2mm
PRIMARY RESISTANCE FORM
Definition – Prevention of tooth or restoration fracture from occlusal forces.
1) Cavosurface angle ー butt joint ー 90 degree - Must be supported by sound dentine - must be located in an area free of occlusal stress
2) Flat Pulpal Floor
3) Internsl line angles ー rounded off
CLASS II
- Gingival beveling ーuse GMTー to give roll resistance
- Unsupported enamel rods(directed towards gingiva) are cut
- Gives strong filling
PRIMARY TOOTH
- enamel rods are occlusally directed
- ∴ no need gingival bevel for class II in primary
PRIMARY RETENTION FORM
Definition – Prevention of dislodgement of the restoration.
Prepare wall configurations- shape, height & form
● Class I
- buccal and lingual wallsー converge occlusallyー or parallel
- mesial and distal walls has to be divergent because dentine will be removed otherwise as dentine is the major supporter / retentive component.
● Onlay ー entire cavity prep will be divergent
● Class II ー create dovetail.
● Q. If a caries at the Marginal ridge? How would you manage?
- Prepare a conservative cavity where wall closer to the marginal ridge is divergent in order to include the caries & Other side parallel.
- No need to make it as a class II preparation.
- Because we always follow preservation method.
Please go to Lecture 21.CONVENIENCE FORM.
SECONDARY RETENTION AND RESISTANCE FORM
May be performed after placing liners and bases.
- Amalgams pins
- Slots - No.35 inverted cone bur
- Boxes
- Coves
- Skirls
- Bevels- Reverse bevels in inlay prep
AMALGAM PINS
➢ For 2 degree retention and resistance form.
➢ Should be placed parallel to line angles.
➢ 2 mm into the dentine & 2mm in the amalgam
➢ Distance between 2 pins ー 3-5 mm
➢ Place minimum/less material and condense (if more - cracks may form)
➢ Pins need not be parallel to each other
➢ Use one pin per missing line angle, cusp or marginal ridge.
➢ Use large diameter pin whenever possible
➢ Use min no. of pins compatible with adequate retention
➢ Complication :- pulp exposure ⇒ DPC + place pin on same day.
➢ Stainless steel pins are used for increased retention & increased resistance.
➢ Types of pins :-
○ Cemented Pin
■ Poor retention
■ Least stress on dentine
○ Friction Lock Pin
■ Better retention
■ More stress on dentine
○ Self Threaded Pin
■ Most retention
■ Most stress on dentine.
■ Yet most preferred
■ Eg : Minikin – 3mm interpin distance
■ Minim – 5mm 8interpin distance
FINISHING EXTERNAL WALLS
★ Gingival bevelling ー GMT
★ To make internal line angles , retentive grooves & preparation of cavity wallsー
ANGLE FORMER
★ Remove unsupported / undermined enamel* rods
○ On floor ー CHISEL (primarily for cutting enamel ok)
○ Proximal wall ー ENAMEL HATCHET
INLAYS
○ Retention factor ー cavity depth
○ Most important bevel ー gingival bevel only
○ Reverse bevel* ー 2 degree retention form
○ Indirect composite inlay will have efficient polymerisation than direct composite inlay
○ 65% Paraffin wax is used to cast inlay
○ Indirect composite inlay overcome direct one by insufficient polymerisation, good contact point, gingival seal
Read from Dental Decks:
✱Amalgam vs Inlay preparation from DD pg4
✱Amalgam vs Composite pg53
✱Reverse Bevel ー Inlays - retention form pg4 DD
Amalgam Shoeing – veneering of non-functional cusp by means of slight finishing bevel. Redection to be done is 1-1.5 mm
Capping – Complete coverage of functional cusp the cusp with amalgam. Reduction needed is 1.5-2mm
CONVENIENCE FORM (comes after primary retention form)
Definition – Alterations to improve access & visibility
Q. The width of cavity preparation = ⅓ inter-cuspal distance.
B. FINAL TOOTH PREPARATION REMOVING REMAINING CARIES + PULP PROTECTION
● If pinpoint caries seen – 1 Point ditching / excavation ⟶ Ca(OH)2 ⟶ base ⟶ Restoration. Check with radiograph
● How to determine Pulp Exposure?
➢ More than 2mm RDT⟶ no need of cavity liner CaOH
➢ If b/w 1-2 mm RDT⟶ RMGI base (may or may not use CaOH liner)
➢ Below 1 mm Or pulp exposure ⟶ Ca(OH)2 (capping) as cavity liner not base or varnish OK ! Then RMGI base.
INSTRUMENT FORMULA
○ 3 DIGIT
WIDTH OF BLADE ー LENGTH OF BLADE ー ANGLE OF THE BLADE
○ 4 No formula ー 2nd no. is added
○ Angle former, Gingival Marginal Trimmer
WIDTH OF BLADE ー ANGLE OF CUTTING EDGE ー LENGTH OF BLADE ー ANGLE OF THE BLADE
GRASPS
○ Modified pen grasps ー most commonly used clinically
○ Inverted pen grasp
○ Palm and thumb grasp ー least preferred clinically [70-110 degree] ー most used in sharpening Instrument
○ Modified palm and thumb grasp
SHARPENING INSTRUMENTS
○ Hand scaling instruments
○ Chisel and all
○ Palm and thumb grasp- Best grasp for sharpening instruments
○ If mounted instrument
■ Fine grains removed
■ Large amounts of material lost
○ If free hand sharpening
■ Large grains removed
■ Less amount
○ Angle ー 70 (Or 110 Degrees)
LINER
CaOH is used as liner when there is pulp exposure- like direct capping – or 0.5mm RDT
Liners should have final film thickness as 5microns.
VARNISH
○ Chemical insulation
○ Prevents microleakage
○ Prevents discolouration from amalgam
○ Most used in 1o tooth for amalgam
○ Contra-indicated in composite - inhibits polymerisation
○ Minimum no. of coats - 2
■ Walls of cavity
■ Floor of cavity
■ Over the amalgam for sensitivity microleakage
■ Over GIC for sensitivity also*
BASE
○ Mechanical and thermal insulation*
○ Replaces the lost dentin
○ Thickness = (0.75 mm) 1-2 mm
○ High modulus of elasticity
Order:-
(OLD CONCEPT)
LINER
VARNISH
BASE
AMALGAM
Now a days bases are more dentine n pulp friendly like GIC, so you don't need varnish below GIC. So answer the question acc to what base is used.
LINER
BASE
VARNISH
AMALGAM
ZINC PHOSPHATE
a. Formed when Zn oxide reacts with phosphoric acid.
b. Micromechanical bond with tooth structure.
c. 1st 24 hours ー irritant to pulp ∵ pH 2
d. After that ー non irritant, pH - 5.9 (24 hours) pH - 7 (48 hours )
e. Mix in maximum increments.
f. Best agent to lute metal ceramic crowns*
g. Apply varnish before ZnPh
Q. Best Luting for ceramic restorations?
Resin luting cement (HEMA+4META+organophosphates)
ZINC POLYCARBOXYLATE/ POLYACRYLATE
Both Zn phosphate & polycarboxylate has ZnO particles
Formed when Zn oxide reacts with polyacrylic acid*
1st material to chemically bond to tooth structure
Bonding with enamel ↑,dentine ↓
Tin / Stannous fluoride is added
Tin increases
a. Working time
b. Strength }1st option
c. Not for fluoride releases (don’t tick such options for exam) OK !
ZINC OXIDE EUGENOL
a. Used as temporary, CO2 pH is neutral and its Eugenol content ー provides palliative effect.
b. Type IV ー used as liner.
c. Biocompatibility is highest -- sedative / soothing action to pulp ー type IV
d. Disadvantage ー causes burning sensation.
e. ZnOE Eba ー modified form ー no burning sensation.
f. Retarded of setting reaction ー glycerin.
g. Acceleration of setting reaction ー acetate water
Increase working time of all above materials :
○ Cool glass slab
○ Alter P/L ratio
○ Maximum increments for Zn phosphates
SILICATES
- Formed when glass particles reacts with phosphoric acid
- Micromechanical bonding
- Used in anteriors earlier.
- 1st tooth coloured material.
- Contains 15% fluoride*
- Can be used as permanent restoration
- Least biocompatible.
- Less chance of plaque growth.
- Contra-indicated in mouth breathing.
GLASS IONOMER CEMENT
a. Refractive index ー close to that of enamel.
b. Thermal expansion ＝tooth structures thermal expansion
c. Most pediatric restorative material ー most common.
d. Compared to composite has more polymerisation shrinkage
LIQUID ー polyacrylic acid ✱Polishing:- Aluminium oxide
i. Bond ー chemically
ii. Adhesive
iii. 10 second surface conditioning / etching
iv. Has macromolecules ∴ biocompatible
POWDER ー Al,Ca ,F ー SiO2 , Al2O3, CaFl
i. Fluoride release - anti-cariogenic property
ii. Fluoride helps in - ceramic flux (AlF,CaF all detaches)
iii. Maturation [complete setting of GIC]- 24 HOURS.
iv. After 24 hours GIC needs wetness for its stability
v. Dry oral cavity [xerostomia, mouth breathers, radiation]- contra-indicated.
Metal - modified GIC
Miracle mix
■ Silver alloy powder is mixed with gic.
■ ∴ abrasion resistance is increased.
■ Strength ー same or decreased.
Cermet
■ Silver alloy sintered with GIC
■ Strength is increased
Resin modified GIC
○ Resin added to gic
○ Setting reaction 2 types ー cold cure & light cure ∴ called dual cure
○ Never used for crown fixation - luting
○ Because it has a tendency to absorb water and this dislodges crown / fracture all-ceramic crowns.
○ Less fluoride* release than usual GIC
○ Used only for cementing post inside canal
○ Better aesthetics, bonding manipulation ease.
Compomer
○ Modification in liquid ie; polyacid modification
● Whereas; GIC ー polyacrylic
● Zn Phospate ー phosphoric
○ GIC modification , liquid polyacid modification
○ Least fluoride release*
○ Resin with fluoride releasing glass.
COMPOSITE
COMPOSITION
● Resin ー chemical name = methyl acrylate (Denture base resin → PMMA)
● Filler ー glass fillers
● Coupling agent ー silane / organosilane*
● Packable and flowable composite difference
○ Viscosityーresistance to flow
● TEGMA is added to increase flow, ie becomes flowable composite
○ Eg: pit and fissure sealants.
FEATURES
● Micromechanical bonding
● Resin tags - penetrate into tooth structure -7 to 25 mm (tag length)
● Ratio of bonded : unbonded Molecules /components→ C factor
● Class I,II,III,IV → hybrid composite
● Class V ー microfilled composite
¤ High polishability
¤ ∴ maximum cleaning efficiency
¤ Or else rough surface → stains, calculus, perio problems etc.
TYPES OF COMPOSITES
MACROFILLED COMPOSITE
a. Average particle size ー 10 μm
b. 1st generation restoration composites.
c. Paste - paste , chemical cure
d. Limited shade matching capabilities
e. Poor physical and mechanical properties
f. Poor esthetics.
MICROFILLED COMPOSITE
g. Average particle size ー 0.04μm
h. Light cured
i. Suboptimal #toughness ー not strong for occlusal bearing area
j. Excellent esthetics and polishability
k. Lower elastic modulus ー better in class V
l. Use primarily in anterior restoration.
HYBRID (MINIFILL) COMPOSITE
m. Average particle size ー 1 μm
n. Light-cured
o. Good properties.
p. Good esthetics but not as polishable as microfilled.
q. Universal use ー anterior and posterior restoration.
MICROHYBRID COMPOSITES
r. Average particle size ー 0.4 to 0.8 μm
s. Light cured
t. Retain good properties of hybrid (strength) with improved handling.
u. Polishability almost equal to microfills
v. Universal use ー anterior and posterior.
NANOFILLED / NANOHYBRID COMPOSITES
w. Filler - 20 nm nanomers 0.6 to 1.5 μm nanoclusters
x. Light cured
y. Excellent handling
z. High polishability
aa. Low shrinkage
bb. Universal use ー anterior and posterior.
FLOWABLE COMPOSITES
cc. High matrix/filler ratio content
dd. Higher polymerization shrinkage
PACKABLE COMPOSITES
ee. Increased viscosity
ff. No documented benefits
ACID ETCHING
● 37% phosphoric / orthophosphoric acid
● 10-15 second
● Also known as conditioning of dentin.
● While GIC by 10% polyacrylic Acid for 10 seconds.
● White frosted appearance
● Objective ー to increase the surface area and remove smear layer*
● Alterations in time
1. Primary tooth(inorganic content is less)ー 30 Secs
2. Fluorosed tooth ー30 seconds
3. Contaminated tooth, when doing re-etching ー etch for lesser time only ー 10 seconds
● What happens during improper / inadequate acid-etching -- bond of composite weakness ー in turn results in microleakage
● If over dried with air after etch ー causes nano leakage
● The time duration for complete remineralization of accidentally etched tooth- 24hrs
● Read generations for DHA, recent gen etc
Dentine bonding
● 10-15second
● 5th generation – 25 Megapascal
● The strength of bonding enamel 25 MP
● While bonding dentin 35 MP.
Composite Curing:-
● Maximum thickness is 2 mm
● Curing tip ー should almost touch ー or at least 1 mm distance*
● Blue colour ー 475 nm
● If laser ー argon laser
● Light ー complication ー can cause retinal damage
● Must give eye protective glasses for cataract patients, eye treated patients
Shade Selection
● Done before starting, before rubber dam
● Dental chair light should be off
● Cure with selected shade first
● If patient comes back after 2 days with complaint of :
○ Darker shade ー due to improper polishing, rough surface takes up stains
○ Lighter shade ー improper curing / polymerisation
Cavity Preparation :-
● No cavity outline, no particular shape
● Outline is determined by caries margin
● Anterior prep ー give beveling is must; retention
● Posterior prepー no beveling at cavo surface angle, 90 degree is okay – Because it can't take masticatory load – might fracture ∴ causes microleakage would happen
BASE UNDER COMPOSITE
Preferred
Ca(OH)2 or GIC or any modifications – RMGI – best
Zn Phosphate
Zn polycarboxylate
Contra indicated
● ZnOE
● Varnish
● Hydrogen peroxide [that's why wait 1 week after intra-coronal bleach (bleaching agents)
Q. Dentist provided bleaching which also known as (home bleaching) (night guard Vita Bleaching) contain : 5 - 22 % carbamide peroxide.
Q. After bleaching a tooth, we want to restore the tooth with composite resin, we don’t want to compromise the bonding, and we wait for: 1-2 Weeks.
FINISHING
Best finished surface is achieved by – 12 fluted bur
Finishing → 12 fluted carbide bur (because high abrasion resistance)
Bur with more number of flutes
Less cutting efficiency & more smooth surface
PIT AND FISSURE SEALANTS
● Deep pits and fissures
● Preventive treatment procedure - prophylactic
● To prevent food lodgement into pit and fissure
● No preparation required
● Composite ー micromechanical ー pit and fissure
● RATIONALE – Act as barrier between the sealed site & the oral environment ー micromechanical
● Etch+bond+flowable sealant + cure
● Use diagnodent ー laser fluorescence ー digital
● Preferred ー recently erupted molars
(ORDER)
¤ Permanent 1st molars(1st preference)
¤ Rest primary molars
¤ Then PREMOLARS
¤ Then ANTERIORS (LINGUAL PITS)
● Retention of sealant ー is the success determination criteria.
● Age of pits & fissures sealant:
○ 3 – 4 y for 1st molars
○ 6 – 7 y for 1st permenant molar
○ 11 – 13 y for 2nd permenant molars & premolars.
Bonding nature of Cements
● Zn polycarboxylate ー chemical
● GIC ー chemical }acrylic liquid
● Composite ー micromechanical
● Pit and fissure ー micromechanical } phosphoric
● Zn phosphoric ー micromechanical
● InLay ー retention
● OnLay ー retention
Prophylactic Rx
● Occlusal only ー pit and fissure
● Others ー fluoride application (not enough for pits – no retention)
● Full mouth ー pit and fissure 1st followed by topical fluoride
GV BLACK CLASSIFICATION
CLASS I
○ Pit and fissure
○ Lingual pits in anteriors
○ Most commonly seen in mandibular 1st molars Because 1st erupting tooth ー highest time of exposure
CLASS 2 PROXIMAL OF PMS AND MOLARS
○ Commonly seen below the contact area
CLASS 3 Proximal of anterior tooth
○ Restorative preference ー composite
○ Exception in Distal aspect of canine ー amalgam
○ Reason ー mesial migration of posterior tooth
CLASS 4 PROXIMAL + INCISAL OF ANTERIOR
CLASS 5 CERVICAL ASPECT
CLASS 6 INCISAL EDGE + CUSP TIP
○ Amalgam shoeing / cusp capping
○ Thickness of amalgam in complex amalgam restoration in cusp tip area 2 - 3 mm.
○ The thickness of amalgam 1.5 – 2 mm.
CLASS V
Cavity prep:-
¤ Extension determined by Caries extension, follow gingival contour.
¤ Occlusal and gingival walls ー arc shaped - Both parallel to each other
¤ Occlusal arc will be longer than gingival arc
¤ Pulpal floor ー convex shape ( to preserve the center of the tooth which is having close proximity to the pulp)
¤ 2 line angles names :- Occlusoーaxial line angle & Gingivoーaxial line angle- retentive grooves [Not Rounded]
¤ Best restorative ー Direct filling Gold - due to its high biocompatibility
¤ Composite ー microfilled – able to get high polishability
¤ After GIC restoration, thin flush is removed by scaler or knife immediately or finishing stone later
Q. The Carat of gold foil used for direct filling restorations is 24.
ROOT CARIES
○ Actinomyces
○ No shape ー caries extension determines the margin of cavity preparation
○ Gingival recession will promote senile caries.
○ Best material ー GIC
○ Old ppl ー RMGIー aesthetic area
DENTAL ANATOMY
HUNTER SCHRUGER BANDS- white & dark lines in enamel appearing in longitudinal section- enamal rods change their direction.
ENAMEL SPINDLES- Extension of odontoblasts that cross DEJ, extend into the enamel
Specific gravity of enamel is – 2.8
Density of enamel crystal is the lowest at – Edge of enamel prisms
Dentine permeability –decreased by smear layer, increases towards the DEJ
Critical PH at which enamel start to demineralization is: 5.
The pH the enamel make complete remineralization: 5.5 or above.
Complete remineralization occur after 24 hours
ph of saliva 6.5
ZONES OF ENAMEL CARIES
SURFACE ZONE
BODY OF THE LESION
DARK ZONE
TRANSLUCENT ZONE
ZONES OF DENTINAL CARIES
NORMAL DENTIN
SUBTRANSPARENT DENTIN (AFFECTED)
TRANSPARENT DENTIN
TURBID DENTIN (INFECTED)
INFECTED / NECROTIC DENTIN
CARIES
Initiation of caries require 4 entities- Host, bacteria, time, crabohydrates
Proximal caries confined within enamel – no fillimg neede only prevention
Only enamel caries and not extending DEJ then :-No Rx required in surface caries. - Only preventive Rx - oral hygiene,wait and watch
- Because enamel can remineralize
Most important factor in increased caries rate in old ppl – Xerostomia
V-shaped cervical liesion – doesn’t require any preparation for gic filling
Incipient careies detected by – fibroptic light
The percentage of simple caries located in the outer wall of the dentin (proximal sides of the tooth) which left without cavitations is around - 60%.
Ultra-Sonic. Devices:magnet. : 25000-40000 RPM, but piezo speed is: 60000 – 80000 RPM.
CMCP contains phenol in concentration: Chlorophenol 35%, Camphor 65%.