Cons Flashcards
Cavity Classification I-V
Blacks classification of caries lesions
I - Posterior Occlusal II - Posterior including Approximal surface III - Anterior Approximal only IV - Anterior Incisal Edge V - Buccal cervical
Setting mechanism of resin composite
Free Radical Addition Polymerisation
Outline setting Reaction of Resin Composite
ACTIVATION
450 nm blue light causes photo-initiator camphorquinone to release free radicals
INITIATION
Free radical reaction with resin matrix monomers
PROPAGATION
Monomers -> cross-linked polymers in an ‘addition polymerisation’ reaction
TERMINATION
Reaction runs out of monomers
Composition of Resin Composite
** Resin Matrix -
Bis-GMA, UDMA (both viscous) and TEGDMA (added to improve flow)
NB: Bis-GMA -> environmental concern (oestrogen like activity) however materials safe once cured.
** Filler Particles -
Inert glass e.g. barium/strontium glass, quartz…
- Reduce polymerisation shrinkage upon curing .’. better seal
- Reduces water sorption
- Reduces thermal expansion
- Increases compressive/tensile strength
- Increases modulus of elasticity
- Increases abrasion resistance
⇒ Radiopacity so visible on radiographs
Shape: Spherical/Irregular
Size: Mixture of small & large particles to occupy more space .’. less resin remaining .’. less shrinkage in curing e.g. Nanohybrid/Nanofilled
** Silane Coupling agent -
(coats filler, allows resin matrix and filler to mix)
Organosilane ( = bifunctional molecule)
- Siloxane end bonds to hydroxyl groups on filler
- Methacrylate end polymerises with resin
** Coupling agent = Sensitive to water - silane filler bond breaks down with moisture!! .’. water absorbed into composites results in hydrolysis of the silane bond and eventual filler loss.
Types of Composite:
Types of Composite:
FLOWABLE Composites
- 50-70% filler content by weight (less than traditional hybrid composite resins → lower viscosity)
- Indications:
o Class V restorations (buccal cervical surface)
o Micro-preparations
o Extended fissure sealing
o Adhesive cementation of ceramic restorations
o Blocking out cavity undercuts
o Initial base layer in any classification - Disadvantages
o Lower filler volumes -> increased shrinkage and wear, decreased strength
PACKABLE Composites (Macrofilled Hybrids)
- E.g.: SDR, BULKFILL
- Firm, can be packed into a preparation
- Contain larger filler particles, or even fibres to improve packing qualities
- High viscosity -> more difficult to sculpt, voids more common
Advantages of Composite
• Appearance - Tooth coloured - Mimics translucency of enamel • Conservation of tooth structure • Adhesion to t.structure via a bonding system • Low thermal conductivity • Command set (LC) • Wear resistant • Withstands occlusal load
Disadvantages of Composite
• Technique sensitive
- Moisture control .’. need rubber dam
- Cannot be placed in wet environments, (subgingival/patients that do not tolerate moisture control)
- Many steps
- Has to be placed in 2mm increments for light penetration
• Polymerisation shrinkage
- Marginal leakage
- Generates lots of stress -> cusp movement
- 2° caries
- Post-operative sensitivity
- Staining
• Lower wear resistance than amalgam
- Not suitable for pts with heavy bruxism
Indications for composite
CLINICAL INDICATIONS • Class III (anterior interproximal), IV (anterior and incisal edge) and V (cervical) • Where aesthetics is important • Rebuilding fractured teeth • Where moisture control can be achieved • Patients with good oral hygiene • Low occlusal load
TYPICAL CLINICAL PROCEDURE OUTLINE FOR COMPOSITE
- Give LA
- Place moisture control
- Gain enamel access and clear ADJ
- Remove infected dentine
- Remove unsupported enamel and bevel margins (if an anterior tooth)
- Etch with 37% phosphoric acid for 15 seconds
- Rinse for 15 seconds
- Dry for 15 seconds (less if dentine to prevent collapse of collagen)
- Apply primer and bond
- Dry lightly with 3in1 to evaporate solvent
- Light cure for 20 seconds
- Place composite in 2mm increments
- Pack and shape
- Light cure for 20 seconds
- Finish
• No flash
• Correct tooth morphology
• Correct occlusion - Polish
• Smooth surface
COMPOSITE IDEAL CAVITY PREPARATION CRITERIA
- No wider than necessary to access caries
- Infected dentine removed
- Affected dentine left
- No unsupported enamel
- Smear layer removed with etch ( bond strength to dentine)
- Bevelled margins if anterior tooth ( surface area for retention and improves transition from tooth to composite for aesthetics)
- Etched enamel and dentine
Bonding system for resin composite
ETCH
37% Phosphoric Acid
Increases SA for bonding -> space/pores for bonding agent to flow into
Enamel -> Calcium salts dissolve, exposes interprismatic and prism areas for interlocking tag formation with the bonding resin = Purely Mechanical Bonding (not true adhesion); bond strength ~20 MPa
Dentine
- > Removes smear layer (Created by any mechanical cutting of dentine, Impairs bond of composite to dentine, Only relatively loosely bound to dentine itself, Can harbour bacteria)
- > Exposing collagen fibres, dentinal tubules & decalcifies intertubular dentine
- >
- Allows penetration of bonding agent into dentine -> Hybrid Layer = infiltration of resin monomers into the collagen fibrillar matrix of demineralised dentine, followed by polymerisation
PRIMER
= solvent + HEMA (resin monomer), an amphiphilic molecule. Hydrophilic end binds to collagen, hydrophobic end binds to bond.
• Penetrates etched dentine tubules
• Applied in a thin layer, thinned with air
• May require light-curing
BOND
= solvent + unfilled resin (hydrophobic).
Binds to HEMA to form resin tags between hydroxyapatite crystals and a hybrid layer where both collagen and resin are found.
- Ultimate goal is achieving marginal integrity and sealing tubules to prevent ingress of bacteria
Why is it possible to use an incremental technique with composite?
OXYGEN INHIBITION LAYER
inhibits polymerisation of monomers .’. top layer sticky to touch - un-polymerised monomer
-> allows next layer of composite to adhere
removed by polishing
Factors in Caries Prevention
Diet control
Toothbrushing
Fluoride
Fissure Sealants
Mechanisms of Fluoride Action
- During tooth formation -> increased stability, increased prism size
- Inhibition of plaque bacteria - interferes with bacterial acid production by inhibition of enolase
- Inhibits demineralisation when in solution
- Enhances remineralisation by forming fluorapatite -> more resistant to subsequent demineralisation (critical pH 3.5 compared to 5.5 for apatite)
- Affects crown morphology making pits & fissures shallower
- Recommend 5:2 (Sugar exposure: F exposure)
Fluoride methods of delivery
Toothpaste- daily
Rinses - daily/weekly
Supplements
Varnishes e.g Duraphat - 2/4 x per year; professional application
Gels - 2/4 x per year; professional application
Water Fluoridation
Devices - slow release F devices
Methods of caries detection
- Visual Inspection - clean, dry tooth, good lighting
- Temporary elective tooth separation
- FOTI - Fibre Optic Transillumination
Used for detection of approximate caries
White light, 0.5mm diameter probe - Bitewing Radiograph
-> minimum radiation dose for maximum caries diagnosis
Caries detectable as radiolucency (darker) on image
Problems of caries diagnosis via radiography
- Overlapping contact points (1/2 enamel thickness = permissible)
- > under diagnosis of early enamel smooth surface caries
- Subjective - inter&intra-observer variability
- Cervical burn out can be mistaken for caries
= relative radiolucency around necks of teeth
Due to X-rays over-penetrating (or burning out) the thinner tooth edge - if CAN see edge of root -> cervical burnout
if Can’t -> possible caries - inner edge more diffuse and rounded in cervical burnout than caries
- Heavily restored dentition
- can’t see what’s happening under restoration
*Angulation of x-ray beam can project enamel lesion so appears to go into dentine
- Mach band effect
= visual illusion
mach band = perceived shadow between enamel and dentine due to different densities
Mask enamel and mach band will disappear - Corrosion products
deposits of heavy metal ions e.g. tin, zinc leached in softened dentine-> radiopaque line under restoration with radiolucency immediately underneath
Reason for restoration failure
- Discolouration
- underlying from stained dentine
- superficial surface staining
- underlying from amalgam corrosion products
*Loss of marginal integrity –> plaque retention
Causes:
-long term creep/corrosion/ditching of amalgams
-marginal shrinkage of resin comp/bonding agent
-marginal dissolution of GICs
-marginal ledges/poor contour/overhangs/marginal chipping under occlusal loading
- Marginal discolouration
= indication of marginal integrity failure; not necessarily recurrent caries - Loss of bulk integrity
- restoration may be bulk fractures /partially/completely lost
- heavy occlusal loading: lack of occlusal analysis before restoring
- poor cavity design: weakened, thin section restorations esp. amalgams
- Poor bonding technique/contamination –> adhesive bond failure/lack of retention
- inadequate condensation technique –> intrinsic structural weakness e.g. voids, soggy bottoms
Factors contributing to appearance of teeth
Outline form Contour Symmetry Proportion Colour - translucency
Facial Symmetry
0.6:1 - relationship between proportions between central & lateral, lateral & canine
Amalgam Advantages
Cheap Longevity; average lifespan 12 years (2001 study) Less technique sensitive than composite Strong Hard wearing Kind to opposing teeth Ag -> antibacterial properties Corrosion products form an effective marginal seal against secondary caries Radiopaque
Amalgam Disadvantages
Non-adhesive
- Requires undercut, retention grooves
- No seal against marginal leakage until corrosion products form
Chemically cured
- No control over setting time; often sets too quickly to carve effectively
Weak in thin section
- Cavity must be made deep enough (>2mm)
Weak if unsupported from underneath
Thermal conductor (however dentine sufficient insulator to prevent being a problem)
Coefficient of thermal expansion
- Expands/contracts depending on temp
Corrosion and creep
Un-aesthetic
Environmental risks of Hg
Can cause lichenoid-type reaction to nearby mucosa
Amalgam Composition
Solid phase=
*Silver (65-70%)
*Tin (26-29%)
*Copper (Low 12%) – reacts with γ2 on setting converting it to γ1
*Zinc (2% max)
– Scavenger; more reactive so prevents oxidation of silver and tin during manufacture by any impurities e.g. oxygen (weakens material). Low % as in presence of moisture can lead to uncontrolled expansion of amalgam filling as it sets.
Liquid phase = Mercury
Amalgam Alloy particles
SPHERICAL (more workable, flows more easily)
or
LATHE CUT (move less freely, helpful when trying to build up teeth). - Modern amalgams contain some of both types – admixed.
AMALGAM SOLID PHASE PARTICLES
**Lathe-Cut Particles – ground up metal, irregular in shape
Does not flow readily
Good for build-up of large cavities
**Spherical Particles – forms by spraying molten metal into water, produces particles of variable sizes
Easily manipulated
Less mercury needed
Less γ_2 produced
**Admixed Particles – mixture of the two (most common)
Best of both
Amalgam Setting Reaction
Once mixed the mercury (Hg) dissolves the alloy powder -> silver (Ag) and tin (Sn) molecules are freed, able to react together or with the Hg forming grains as the material sets.
Ag + Sn -> Ag3Sn (γ)
Ag + Hg -> Ag2Hg3 (γ1)
Sn + Hg -> Sn7Hg (γ2) - undesirable phase; causes amalgam to be weaker and more prone to corrosion and creep
To avoid too much γ2 forming copper is included. Cu undergoes a reaction with any γ2 as follows:
Sn7Hg (γ2) + Ag-Cu -> Cu6Sn5 + Ag2Hg3 (γ1)
γ_2 = undesirable, causes strength, corrosion (results in a dull appearance) and creep (results in marginal failure and secondary caries)
Amalgam corrosion products
Although amalgam does not bond to dentine, the corrosion products formed around the edges of the restoration form an extremely effective seal. This combined with the inherent antibacterial properties of silver form a good barrier to microleakage and secondary caries.
Amalgam Indications
- Class I (posterior occlusal) and II (posterior occlusal and approximal)
- High occlusal load
- Where aesthetics unimportant
- Build-up of heavily broken down teeth prior to crowning
- Nayyar core – build-up of heavily broken down, endodontically treated teeth prior to crowning
Ideal Cavity Preparation considerations
• No wider than necessary to access caries
• Remove infected dentine
• Leave affected dentine
• Must be at least 2mm deep minimum
• Cavo-surface angle - 90° or greater
• Amalgam-margin angle - 70° or greater
• No unsupported enamel
• Approximal cavity should just clear contact point
• Flat margin floor (better packing, resistance to dislodgement)
• Retention (feature which opposes vertical displacement)
o Undercut
o Bonding (e.g. RMGIC)
• Resistance (feature which opposes horizontal displacement)
o Retention pit/groves in cavity floor
o Occlusal key; dove tails which extends the cavity into sound tooth along the natural pits and fissure in teeth
Amalgam Packing
- Place increment of amalgam into a cavity & pack firmly into place
- Small instrument first to push into crevices, grooves, corners, deepest parts of cavity preparation
- After, use larger instrument repeatedly
- Overfill cavity
- Vigorous packing brings mercury to the surface
Amalgam Carving
- Place increment of amalgam into a cavity & pack firmly into place
- Small instrument first to push into crevices, grooves, corners, deepest parts of cavity preparation
- After, use larger instrument repeatedly
- Overfill cavity
- Vigorous packing brings mercury to the surface
Amalgam Burnishing
• Smoothing the restoration margins using a burnishing instrument
Amalgam Polishing
Amalgam should be left at least 24 hours before polishing takes place.
Polishing has many advantages:
- Restoration has a smoother surface which is less plaque retentive
- Feels smoother to the patient
- There is a rearrangement of the structure of the surface of the metal that makes it less prone to corrosion.
However it is not always recommended as the resulting restoration is not going to last longer, may generate heat in the process and occlusal interferences are less easy to spot.
Amalgam Safety
The problem
• Amalgam is approximately 50% mercury
• Mercury vapour is highly toxic
Central nervous system
Kidneys
• Mercury vapour is ingested whenever amalgams are mixed, placed or removed
• Mercury vapour is released from filling during chewing and toothbrushing
• However most authorities think that the adverse effects of having amalgam restorations is negligible, there are some dentists that believe in “metal free” dentistry, though little strong evidence backs up this position
- When mercury enters the environment it can be converted by bacteria into methyl mercury (MeHg) in fresh and salt water
- Methyl mercury is highly poisonous
- It enters the food chain – commonly by fish
- It is concentrated in the food chain – bioaccumulation
- Several serious health incidents have occurred due to this
Safe handling of amalgam
Regulations in place to limit environmental pollution
• Wear masks, gloves, eye protection
• Traps in suction, spittoon and sinks
• Use high volume suction while carving
• Waste amalgam stored in special containers – or under fixative
• Dappens dishes and used capsules disposed of in separate waste
• Disposal carried out by specialists
• Mercury spills dealt with efficiently
Minimata Convention
United Nations convention looking at the safety of mercury containing products, there were a number of recommendations that have been adopted by our government
• Ban on Mercury containing products and “phase down” of amalgam by 2020
• Call for a cease to teaching amalgam by 2015
• Little agreement over protocols between schools
• “Like it or not, composite will become the most widely used type of material in the restoration of posterior teeth “
TYPICAL CLINICAL PROCEDURE OUTLINE
- Give LA
- Gain enamel access and clear ADJ
- Remove infected dentine
- Remove unsupported enamel, ensuring cavo-surface angle is >90 degrees
- Modify cavity to produce undercuts, keys and grooves
- Place matrix band and wedge if required
- Apply RMGIC liner (Fuji II) to dentine for moderate/large cavities
- Light cure for 20 seconds (unless bonded amalgam)
- Mix amalgam for 8 seconds
- Load amalgam carrier
- Place amalgam in cavity gradually, packing hard to bring excess mercury to the surface (remember to over-fill cavity, allows excess mercury to rise)
- Remove wedge and matrix band if placed
- Shape and carve
• Smooth surface
• Correct occlusion
• Correct tooth morphology - Burnish once set
Indications for placing a bonded amalgam
Before filling, assess the cavity. If it has any of the following problems, consider a bonded amalgam:
• Cuspal loss
• Good retention features not achievable due to destruction of tooth tissue
• Good resistance features not achievable due to destruction of tooth tissue
Unlike when a liner is placed for deep amalgam restorations, the RMGIC is not light cured prior to packing the amalgam on top.
GIC Advantages
ADVANTAGES
• Chemically bonds to tooth
- no bonding agent needed
- conservative; minimal cavity prep as no undercuts/bevelling required
- adhesion to dentine & enamel = complete chemical bond .’. no gap minimising 2o caries
• Fluoride release and recharging (GIC) with topical fluoride exposure – high caries risk pts
• Streptococcus mutans growth inhibited by GIC restorations – greatest effect as material sets (long term appears negligible)
+ F release
+ Plaque does not thrive on it
+ Inhibits bacteria due to F release
+ Promotes dentine bridge formation in pulp-capping due to low pH
+ Chemically set, fewer placement steps than RMGIC and composite
+ Quick and easy to place, good for children and those who do not tolerate dental procedures
+ Can be placed in damp environments
+ Bonds to tooth, minimal cavity preparation required
GIC Disadvantages
• Technique sensitive
• Moisture sensitivity – don’t want ions to be lost into saliva as needed for cross-linking & setting – needs to be kept dry for 7 days after placement so protect with varnish so moisture control can be achieved -> significantly improves strength of GIC
• Cannot be placed in stress bearing areas
• Low tensile and facture toughness -> shorter mean survival time ( Amalgam = 11 yrs, GIC – 6 yrs)
• Poor wear resistance – precludes use in posterior restorations
• Only average aesthetics (GIC changes as material sets)
- Colour changes overtime
- Can’t polish; poorer surface finish, don’t shine like composite
- Limited range of colour shades
- Sensitive to water during placement (contaminates materials, causes hardness and shrinkage)
- Sensitive to water after placement (causes ion loss = strength)
- Weak, cannot be placed in load-bearing locations
- Poorer survival rates vs. amalgam and composite
- Poor wear resistance
- Fewer shades available than composite
- Poorer aesthetics (due to fewer shades and poor translucency)
- Low tensile strength
What is GIC
= Glass polyalkenoate cement = Hydrophilic - Water based, plastic cement - Subgingival restorations - Temporary restorations - Stepwise excavation - Traditional: Chemfill, Fuji Triage, Fuji IX, condition & varnish - Zinc reinforced GIC (Zn replaces Ca) Chemfill rock, no conditioner/ varnish required
Glass Polyalkenoates:
• Formed by an acid-base reaction between a fluoride containing glass and a poly acid (usually poly acrylic acid)
• Adhesive
• Cariostatic
• Chemically bonds to tooth – no bonding agent needed
• Releases fluoride
RM-GIC
Resin modified glass polyalkenoate
= Hydrophilic
- HEMA (resin component), water mixture base
- Non-load bearing restorations
- Bonded amalgams
- Fuji II, condition, LC, no varnish required
GIC Composition:
**Fluoro-alumino-phospho-silicate glass (powder) with strontium (radiopacity)
Typical ionomer glass formulations:
SiO2, Al2O3, AlF3, CaF2, NaF, AlPO4, NA3AlF6 – structured ionically as a tetrahedron complex with a centrally located Al ion and closely localised alkaline earth cations (Na, P, Ca, Sr) to maintain electro-neutrality.
SiO2 – affects transparency
Al2O3 – affects opacity, setting time, can compressive strength of set cement
CaF2 – fluoride ions: fusion temp, strength, enhance translucency, therapeutic effect (disease healing)
**Polyacid e.g. polyacrylic acid (liquid)
GIC Setting Reaction
POLYACID + BASE → POLYSALT + WATER
Polyacid + water → COO- + H+
- DISSOLUTION: H2O causes H+ ions to be liberated from COOH groups, leaving COO- groups. H+ attacks glass particles → ions released; CaF2 and AlF3 to exit glass, leaving an ion-depleted layer.
- MIGRATION of ions
- GELATION: Ca2+ and Al3+ bond to COO- groups, forming cross-links between polyalkenoic acid chains in an acid-base reaction. F- free to move out of material into external environment. Ca2+ in hydroxyapatite crystals also bond to COO- groups.
- POST-SET HARDENING: Takes a few minutes as further cross-links form
- MATURATION: Precipitation of Al3+ salts continues for 24hrs. Setting process continues at a very slow pace for up to 1 year; properties increase over time. Continued formation of polysalts; hydration of the polysalts, expanded gel structure.
GIC: Fluoride release
Fluoride released into polysalt matrix from the glass by the acid attack, but plays no role in setting reaction .’. can be released without upsetting the structure of the cement.
Ions lie free within the matrix and can be released from the restoration into the surrounding tooth structure. Contributes to the biocompatibility of the material and it’s capacity to inhibit recurrent caries.
Fluoride release:
• Rapid initial process -> early burst of fluoride release
• Second slower much more sustained process responsible for long-term release of fluoride
• Can recharge by topical fluoride exposure – will take in and re-release
NB: main reason for replacement of GIC restoration is secondary caries – contradiction?
Water and GIC restorations
Water plays an integral role. Slowly hydrates the mature cross-linked matrix -> o Increased strength o Improved translucency o Increased resistance to desiccation
However moisture sensitive
Excess water -> Contamination -> Increased opacity (loose translucency)
-> Decreased strength/hardness
Loss of water -> Desiccation -> Increased cracking (.’. protect with a varnish after it sets)
GIC Bonding to tooth structure:
Ca2+ binds to COO- groups on polyalkenoate chains
Bonding to collagen theorised but no so well proven
Biocompatibility of GIC
- Plaque doesn’t thrive on glass-ionomer surface
- Streptococcus mutans growth inhibited by GIC restorations – due to fluoride present, greatest effect as material sets but long term appears negligible
- Soft-tissue and pulpal response to GIC favourable
Applications for GIC
- Cementation of rigid restorations
- Restorations of primary teeth – v.good outcomes in paediatric dentistry
- Class III and V carious lesions
- Crown margin repair
- Temporary dressing – carious cavity, fractured tooth, RCT
- Base under amalgam and composite
- Cavities extending below the ADJ
- Temporary fillings
- RCT inter-appointment dressings (contrasting colour, ChemFil Rock Contrast White or Fuji Triage)
- High caries risk patients
- Paediatrics
- Luting cement for crowns (Fuji +)
- Fissure sealants
- Covering pulp caps
- Low occlusal load
- Where aesthetics is unimportant
What is RMGIC
• GIC + small quantity of resin components (4.5-6%)
• Less water – replaced by a water/HEMA mixture
- HEMA = hydroxyethyl methacrylate
NB: severely irritating to the eye, is a known contact allergen. Small % of population known to have allergic response to acrylate resins. Reduce risk of allergic response by minimising exposure to material especially exposure to uncured resin .’. use of protective gloves and a no-touch technique is recommended.
• In addition to the acid-base reaction, the Polyacid contains polymerisable functional groups - LC
RMGIC advantages
- Tooth coloured
- Command set
- Improved aesthetics
- Medium fluoride release
- “Recharges” (but lower fluoride release than GIC)
- Shorter setting/Command set (LC); longer working time
o Modification of the Polyacid with side chains that can polymerise by light-curing mechanisms - Decreased moisture sensitivity
- Improved tensile strength
- Better wear characteristics
- Easier to use
- Higher bond strength than composite
- Can finish immediately
- Resistant to desiccation; resin = hydrophobic, prevents water entering & ion loss .’. don’t need varnish
\+ Plaque does not thrive on it \+ Inhibits bacteria due to low pH \+ Stronger than GIC \+ Command set, operator in control of setting \+ No varnish required on surface \+ Resistant to ion loss \+ Better wear resistance than GIC \+ Fewer placement steps than composite \+ Bonds to tooth, minimal cavity preparation required \+ Better aesthetics than GIC
RMGIC disadvantages
- Resin prevents RMGIC acting like GIC – as soon as light cure material “freezes”; no/less ion movement, no/less fluoride release
- Polymerisation reaction → marginal shrinkage
- F not released after light-curing
- Cannot be placed in load-bearing locations
- Does not come in as many shades and composite
- Unaesthetic compared to composite
RMGIC Indications:
- Cervical and root caries i.e. cavities extending below CEJ
o High caries risk – F release
o Poor moisture control (GCF) – conventional GIC can’t set there - Base
- Abfraction lesions
• Cavities extending below the ADJ (Fuji II LC)
• Root caries
• Lining deep cavities (Fuji liner)
• Bonded amalgams (Fuji liner)
• Covering pulp caps (Fuji liner)
• Fissure sealant
• Low occlusal load (Fuji II LC)
• Where aesthetics is important but composite cannot be used
• Paediatrics
• Cementing crowns (Fuji PLUS)
Dentine conditioner GIC/RMGIC
Polyacrylic acid (10%)
Removes smear layer. 10 secs, wash, gently dry (doubles bond strength)
GIC - TYPICAL CLINICAL PROCEDURE OUTLINE
- Give LA
- Gain enamel access and clear ADJ
- Remove infected dentine
- Remove unsupported enamel
- Place plastic matric band/strip and wedge if required (GIC sticks to metal)
- Remove smear layer using dentine conditioner (10% polyacrylic acid) for 10 seconds
- Wash for 10 seconds
- Dry cavity if possible
- Mix GIC for 15 seconds
- Place GIC
- Shape GIC
• Smooth surface
• Correct occlusion
• Correct tooth morphology - Keep area as dry as possible while it sets
- Place two layers of cured OptiBond on the surface (to prevent ion loss in wet environments)
RM-GIC - TYPICAL CLINICAL PROCEDURE OUTLINE
- Give LA
- Gain enamel access and clear ADJ
- Remove infected dentine
- Remove unsupported enamel
- Place plastic matric band/strip and wedge if required (RMGIC sticks to metal)
- Remove smear layer using dentine conditioner (10% polyacrylic acid) for 10 seconds
- Wash for 10 seconds
- Dry cavity if possible
- Mix RMGIC for 15 seconds
- Place GIC
- Shape GIC
- Light-cure for 40 seconds
- Finish
• No flash
• Correct tooth morphology
• Correct occlusion - Polish
• Smooth surface - Light-cure for 20 seconds
4 zones beneath a root apex in irreversible pulpitis
- Infected
- Contaminated
- Irritated
- Stimulated
SOCRATES
Site Onset Character Radiation Alleviating factors Time Exacerbating factors Severity
Indication for Fissure Sealants
Pits & fissures
= 12.5% of tooth surfaces
= 66% of all carious lesions
Definition: A fissure sealant is a material that is placed in the pits and fissure of teeth in order to prevent the development of dental caries
Highly effective at preventing dental caries – - Caries reduction 60%.
- Retention rate of 52% up to 4 years.
(Ahovuo-Saloranta et al. 2008)
FS on risk assessment basis of pt selection
- children with impairments e.g. motor difficulty; can’t brush teeth effectively
- bleeding dosorder - treatment of caries could be detrimental/cause adverse effects
- caries present in primary dentition
Clinical steps to FS
- Effectively clean pits and fissures
- Isolation of tooth = vital
- > rubber dam, if not need assistant to monitor pt to ensure don’t wet tooth with tongue
- Etch tooth, wash & dry
- Apply sealant (Bis-GMA resins/GIC)
- LC -> polymerisation
- Evaluate
- no inter proximal application of sealant, no ledges, flush to tooth surface
- Follow up
- examination + radioraphs
5-10% fail/year
PRR
Preventative resin restoration
small occlusal cavity
use oppose at base of cavity
then fissure seal surface and surrounding fissures
Adv: Conservation of tooth surface Aesthetics Improved seal Halts caries progression
Clinical steps:
- LA
- Isolation
- Preparation
- Composite restoration
- Sealant application
Diagnosis of stained fissure
Look at borders around discolouration
opaque -> carious
nothing -> staining
Dentinal Caries layers
- Open Carious cavity
- Infected Dentine
Most coronal layer
Exposed to oral environment through open carious cavity; saliva & bacteria access
No discernible structure due to proteolytic bacteria (using type 1 collagen as substrate) - Gross disruption of organic fibrillar matrix so not recognisable as possessing dentinal tubules, peritubular or intertubular dentine
Heavily infiltrated with bacterial colonies
As descend deeper through the infected layer the colonies become fewer and recognised structure of dentine becomes more visible at the microscopic level and less disrupted - Affected Dentine
Closer to the pulp in position
There is a recognisable dentine structure - Fibrillar structure present
Affected by the incipient acid wave of demineralisation which precedes bacterial invasion as it proceeds down the dentinal tubules towards the pulp
Acid demineralisation → dentine slightly demineralised as the HAP crystals are being dissolved
Softer than normal dentine due to wave of acid demineralisation
Very few bacteria – possible to see isolated bacteria in superficial zones but not heavily infiltrated - Normal Dentine
Not infected with bacteria
Has dentinal tubules – there will be evidence of sclerosis as the odontoblasts lay down reactionary/secondary dentine inside the tubules to provide a more impenetrable barrier to invading bacteria
As caries gets deeper to pulp layer becomes thinner so risk of direct pulpal exposure becomes much greater
Likely that are many micro-pulpal exposures long before get a frank visible exposure in this layer - Pulp chamber
Possible causes of dentinal tubule exposure include:
Possible causes of dentinal tubule exposure include:
1 - Gingival Recession
2 - Caries
3 - Trauma
4 – Toothwear; Erosion, Abrasion, Attrition
Inflammation of the pulp may be due to:
- Caries
- Trauma
- Abrasion, Erosion, Attrition
- Restorative Procedures
STEPWISE Excavation Technique
– must have reversible pulpitis, can’t have irreversible pulpitis!
Achieve adequate local anaesthesia
Use rubber dam isolation
Open occlusal enamel surface and follow caries outline at ADJ
Ensure that dentine at the ADJ is caries free (dentine sooth, hard and unstained) and there is no unsupported enamel
Infected dentine then remains on pulpal floor and/or axio-pulpal walls
Carefully excavate soft and wet infected carious dentine, leave affected (organised, uninfected)
Cover affected dentine with CaOH containing cement, place RMGIC liner/base cement and restore cavity with appropriate long-term restorative material
INDIRECT pulp capping technique
• Stepwise excavation
• CaOH
Affected dentine covered with layer of CaOH releasing cement liner e.g. Dycal – the CaOH makes area alkaline -> bactericidal and promotes remineralisation of affected dentine and laying down of reparative dentine
• RMGIC
Floor of cavity covered with RMGIC base cement, cavity filled up to leave 2-3mm of space for final restoration to be placed
Adhesive -> minimises micro-leakage
Releases F during setting rxn-> encourages remineralisation of AD
• Definitive restoration
DIRECT pulp capping technique
= how to deal with an iatrogenic pulp exposure
Gently wash exposure and gently dry with a cotton wool pledget
Haemorrhage should stop within 30-60 secs
Exposure covered with setting CaOH cement (e.g. Dycal)
Seal over with an RMGIC cement base
Restore with a definitive restoration with a good coronal seal
Most successful when:
Exposure
CaOH
- Setting e.g. Dycal, MTA, Biodentine
- Non-setting e.g. Hypocal, Calsept
Properties of calcium hydroxide
• Very high pH (pH 11-11.6)
• Creates alkaline environment i.e. bactericidal (highly toxic to bacteria)
• Dissolves dentine substrate releasing tissue growth factors
• Stimulates odontoblasts to lay down new reparative dentine in dentinal tubules
• Stimulates stem cells in the pulp tissue to create new odontoblast-like cells to create dentine bridges across pulpal exposures
