Restorative Flashcards
Amalgam composition
Mercury Tin Silver Copper Zinc
What does tin do in amalgam?
Critical to setting reaction
Controls dimensional change
What does copper do in amalgam?
Prevents corrosion
Reduces fracture
Eliminates Gamma 2
What does zinc do in amalgam
Scavenger for oxygen
What does mercury do in amalgam?
Wets alloy and initiates setting reaction
What is the gamma 1 phase of amalgam?
Silver and mercury
What is the gamma 2 phase of amalgam?
Tin and mercury
Responsible for early fracture and failure
3 Types of Amalgam
Spherical: amalgamates more readily, less mercury required
Lathe-cut
Admixed: better proximal contacts
Both spherical and admixed are marketed today
What is the amount of creep amalgam can have to be ADA certified?
Maximum 5% creep
Occurs under loading
Modern alloy should not have more than 1% creep
Does amalgam or composite have more dimensional change?
Composite (2%)
Amalgam has 0.2%
What is the only restorative material in which the marginal seal improves over time?
Amalgam
What is the eta phase of amalgam?
Copper and Tin
3 forms of mercury
Elemental: liquid at room temperature, used in amalgam
Organic: methyl mercury (most toxic) and ethyl mercury - formed in water/soil by bacteria, can build up in fish
Inorganic: enters air from mining or deposits, burning coal/waste
Main human exposures to mercury
Mercury vapor from dental amalgam
Methyl mercury from seafood
Inorganic mercury from food
Threshold for health hazards from air/mercury
5 g/m2 for adults
1 g/m2 for kids and pregnant women
This is well-below daily amalgam associated exposure
What is the primary risk to dental personnel for use of amalgam?
Inhalation
How to reduce plasma and urine mercury levels during dental restorations
Use rubber dam
Use high speed evacuation and water spray
Do not heat sterilize amalgam
More mercury removed when fillings are removed than when placed
New England Children’s Amalgam Trial
534 children between 6-10 years of age with no prior amalgam
Assignment to amalgam (vs composite) associated with higher mercury level
No association with IQ, urinary albumin, general memory index or visuomotor composite
Indications for Amalgam
Class II preparations that do not extend beyond the line angles
May be inappropriate for primary 1st molar in children 4 and younger
Amalgam Preparation Design
Pulp floor depth 0.5mm into dentin
Isthmus 1/3 of intercuspal width
Carved anatomy should be shallow
Convergent walls occlusally
Broader proximal box at cervical portion than occlusal
Gingival wall is flat, not beveled
Axial wall 0.5mm into dentin with 1mm wide gingival seat
Trituration of Amalgam
Under triturated (most serious error) appears dry and sandy, sets rapidly
Higher trituration speed gives less working time
Back-to-back restorations should be condensated simultaneously
Amalgam longevity vs composite
Up to 7 times more need for repairs of composite compared to amalgam
Need for additional restorative treatment 50% higher with composites versus amalgam historically
3 Phases in Composite
Resin (matrix)
Surface (interstitial or continuous) - binds to organic resin matrix to inorganic fillers
Dispersed (reinforcement, filler)
Composite oligomers
All composite have dimethacrylate oligomer such as Bis-GMA, Bis-EMA6 (larger), siolorane monomer
Larger oligomers (TEGDMA or Bis-6) have less shrinkage
Filler sizes of composite
Microfilled: 40nm
Nanofilled: 20-75nm
Hybrid: 40nm and small particle (200-300nm)
Flowable: 45-75% filler
Does more resin result in more or less shrinkage?
More
What does larger particle size do? What does smaller particle size do?
Larger = strength Smaller = polishability
Microfilled composites can achieve better polish more quickly; used for esthetic restorations
Indications for composite
Class I restorations
Class II restorations that don’t extend beyond line angle (except when exfoliating in 1-2 ears)
Class II restorations in permanent tooth extending 1/3-1/2 B/L intercuspal width of tooth
Indirect resins allow more complete polymerization of resin and reduced shrinkage
Contraindications for composite
Young children at high caries risk
Tooth cannot be isolated
What does beveling do in composite?
Removes the prismatic layer of enamel, which may not etch well
What is the increment of composite that can be placed at a time?
2-4mm
How do you achieve the best contact for back-to-back restorations?
Do one at a time
What is the typical polymerization shrinkage of most composites?
1-5.7%
Newer composites are lower
Advantages of bulk fill composite
Increased depth of cure (4-5mm)
Decreased time to cure (20s)
Less technique sensitive
Disadvantages of bulk fill composite
Greater translucency, poorer esthetics
Extra equipment
Shrinkage/post op sensitivity
Etching
Overcomes smear layer, obstruction of dentin tubules
Liquid and gel produce similar results
No significant difference of resin bond strength etching for 20 or 60 seconds
Bonding Agent
Solutions of resin monomers with hydrophilic and hydrophobic groups
Rely on phosphate-calcium bond for retention
Hybrid Layer
Mechanical bond created when the smear layer is removed, monomers infiltrate into demineralized dentin, polymerize and interlock with dentin matrix
How does composite bond to dentin?
Micromechanical retention
Little evidence supports chemical bond
Glass Ionomer Physical Properties
Chemical bonding to enamel and dentin Thermal expansion similar to tooth Less shrinkage than resin Uptake and release of fluoride Hydrophilic
What is the only dental material that has potential for true adhesion to tooth structure?
GI
3 Categories of GI
Luting
Restorative
Base/Liner
Composition of GI
Base: calcium or strontium alumino-fluoro-silicate glass powder
Acid: polyacrylic acid
How does GI bind to dentin?
Hydrogen bonds at tooth surface
Free hydrophilic carboxyl groups form the bond
How does GI release fluoride?
Hardening reaction involves neutralization of acid by powdered glass base
Fluoride is released by reaction from calcium and aluminum ions binding to polyacrylic acid
Requires presence of water
How does GI result in tooth sensitivity?
If not sufficient water is present, GI takes water from dentin tubules
Is GI recommended for class II restorations in primary molars?
No
Conventional GI is not recommended
RMGI
Conventional glass ionomer formulation with addition of resin monomers of acrylic acid and methacrylate like HEMA
Triple Hardening of RMGI
Initial curing of light-sensitive resin
Chemical resin cure
GI acid/base neutralization matures over time
Sandwich Technique
GI or RMGI is used to replace dentin, composite is overlaid as a bonded enamel replacement
Ionomer bonds adhesively to tooth, bonding agent bonds mechanically between ionomer and enamel
Advantages of Sandwich Technique
Decreased marginal leakage
Reduced sensitivity
Reduced shrinkage
Improves esthetics of GI/RMGI only
Indications for RMGI
May be considered for class I and II restorations in primary teeth Class V permanent teeth
Insufficient evidence for long-term restorations in permanent teeth
RMGI compared to composite
RMGI has less wear resistance
RMGI has lower fracture strength
RMGI placed without occlusal dovetail is more likely to show adhesive failure
Compomer
Polyacid modified resin composite
72% strontium fluorosilicate glass and resin matrix to allow for release of fluoride
Does NOT recharge with fluoride like GIC
Not hydrophobic
No bond to tooth structure (must be used with adhesive)
Compomers for restorative material?
Not enough data to compare compomers to other restorative materials
Resins have better mechanical properties than compomers
Should you acid etch with compomer?
Not according to manufacturer instructions, but studies found better bond strength with enamel acid etch
Bioactive material compositions
56% filler
21% bioactive glass filler
Bioactive ionic resin matrix
Rubberized resin
Properties of bioactive materials
Some chemical bond to teeth No Bis-GMA or BPA derivatives Releases calcium phosphate and fluoride Reportedly greater deflection to break than composite or RMGI Light cure 20s, chemical cure 2 min
Technique for bioactive materials
Etch 10s Use bonding agent in non-retentive prep Dispense into preparation Use up to 4mm Allow to be in contact for 20-30s Light cure
Does ACTIVA, composite, or RMGI have greater microleakage?
ACTIVA has greater microleakage than composite or RMGI
What type of steel is used in SSCs?
316 Stainless Steel
Orthopedic surgery type
Composition of SSCs
65-73% iron
17-19% chromium
Some nickel
Indications for SSCs
After pulp therapy Multisurface caries in high risk Proximal box extending beyond line angle Fractured teeth Teeth with extensive wear As abutment for space maintainer Multisurface lesions when restoration needed more than 2 years or if patient is younger than 6
Contraindications for SSCs
Patients undergoing MRI of head and neck
Patients with nickel allergy
Teeth exfoliating in 6-12 months
Indications for permanent tooth SSC
Interim restoration
When finances do not allow lab-fabricated crown
Teeth with developmental defects
Permanent tooth requiring full coverage but partially erupted
Technique for permanent tooth SSC
1.5-2mm occlusal reduction
Restore original morphology with buildup before cementation
BW radiograph to verify fit
Comparison of SSCs versus amalgam and composite
SSCs have highest success rates
Amalgam failure 2-7x SSC
Cost per patient is lower when teeth restored with SSCs due to fewer replaced restorations
Reasons for failure of SSCs
Crown loss
Perforation
Gingival health and SSCs
Crowns with poorly adapted margins show gingivitis
Extension of crown not associated with gingival health
Poor OH associated with unhealthy gingiva around SSCs
Primary tooth SSC technique
Occlusal reduction 1.5mm Proximal reduction without ledges (feather edge) Round line angles Minimal buccal and lingual reduction Crown seats 0.5-1mm subgingival
Cementing SSC
Bonded resin cement has greater tensile strength and retention with least microleakage - may have isolation problems
GI or RMGI is acceptable
Do NOT use polycarboxylate cement
Purpose of base/liner
Reduce marginal microleakage
Prevent sensitivity
Calcium hydroxide formulation
Catalyst paste: Ca(OH)2, zinc oxide, zinc serate in ethylene toluene sulfonamide
Base paste: calcium tungstate, calcium phosphate and zinc oxide in glycol salicylate
Calcium Hydroxide Properties
Alkaline pH prevents bacterial invasion
Hydrolysis and microleakage
Should use less soluble high-strength base over calcium. hydroxide
Zinc Oxide Eugenol formulation
Powder: zinc oxide, rosin and zinc acetate
Liquid: eugenol
ZOE properties
Sedative effect for pulp
Low compressive effect
Eugenol is inhibitor for polymerizing resins
Hall Technique Success
Up to 98% successful
More successful than intracoronal restorations
No different than traditional SSC
Alternative Restorative Technique
Means of restoring and preventing cares in populations with little access to traditional dental care
Developing countries
Interim Therapeutic Restoration
May be used to restore, arrest or prevent progression of caries where traditional restoration is not possible or desirable
Fluoride releasing materials, no anesthetic, minimal tooth structure removal
Not great for interproximal restorations
Failure from ART/IRT?
Inadequate cavity preparation
Loss of mechanical retention
Esthetic posterior SSCs
Major problem is chipping and loss of preveneered facings
More reduction than SSC, cannot be crimped/adapted as much
Moisture/heme control is less of an issue compared to zirconia
Why are class III restorations difficult in primary teeth?
Small clinical crowns
Large pulp chambers
Thin enamel
May need labial or lingual dovetail
Indications for full coverage for primary incisors
Multiple carious surfaces Incisal edge involvement Extensive cervical decay Pulp therapy Hypoplastic Poor moisture or hemorrhage control Large single-surface lesions Discolored incisors that are esthetically unpleasing
Are zirconia or SSC more resistant to fractures?
SSC
However all crowns exceed maximum bite force of children 6-8 years
Main reasons for zirconia failure?
Loss of crown
Infection
Is gingival health better around SSC or zirconia?
Zirconia
Advantages of zirconia
High strength
Abrasion resistant
Biocompatible
Color-stable
Disadvantages of zirconia
Greater tooth reduction
More technique sensitive
Higher cost
Can cause abrasion of opposing teeth
Prosthetic replacement of primary incisors
Space maintenance typically not required for incisors
Ideal to allow 6-8 weeks following tooth loss before appliance fabrication but can be done immediate
Bands or SSCs on primary molars are abutment for anterior pontic teeth
Diastema closure
Orthodontist can help have optimal arrangement of teeth for closure
Partial diastema closure may be a good option
Microabrasion
Esthetic treatment of hypoplasia
Hydrochloric acid 6.6% in slurry of silicon carbide microparticles
Follow with fluoride treatment
Full coverage restorations of permanent teeth
Reduction of all ceramic materials are less than metal-ceramic (1.5mm vs 2mm)
Posts and cores do not strengthen teeth (only indicated with inadequate structure)
Veneers require 0.3-1mm tooth structure removal
Vital Bleaching
Hydrogen peroxide, carbamide peroxide or sodium perborate
Home bleaching: carbamide peroxide
Office: hydrogen peroxide, rubber dam, light
Carbamide peroxide is 1/3 what hydrogen peroxide is
-ex: 10% carbamide peroxide is 3.3% hydrogen peroxide
Side effects of vital bleaching
Sensitivity
Tissue irritation
Marginal leakage of restorations
Nonvital bleaching - walking bleach technique
Walking bleach technique
- open RCT, ensure no pulp remains
- clean with alcohol
- create cervical seal below CE
- sodium perborate mixed with water
- change after 3-7 days
Side effects of nonvital bleaching
Increased marginal leakage of existing restoration
External root resorption
Ankylosis
Issues with dental implants in pediatrics
Impact of growth on position of impact
Effect of implant-supported prosthesis on growth and development
Implants in mandible
May be done in patients with ectodermal dysplasia
Mandible has less change, so implants can be done earlier
Posterior mandible implant placed too early may lead to lingual positioning of implant
Implants in maxilla
Can give rise to diastema
Prosthesis of midline can inhibit growth
Pubertal growth spurts
Boys: 11-17 years
Girls: 9-15 years
Important to consider growth for implant placement
Dental lasers
Device that generates intense beam of coherent monochromatic light by stimulated emission of photons from excited atoms or molecules
Differences primary teeth from permanent
Enamel is thinner Greater dentin thickness over occlusal fossa Pulp horns are higher Pronounced cervical ridges Enamel rods slope occlusally Marked cervical constriction Longer, more slender roots Roots flare out
Crowns of primary teeth
Shorter than permanent teeth Wider MD Narrower occlusal table Cervical constriction Broad, flat contacts Prominent MB bulge No developmental grooves/mamelons on incisors Thinner enamel Lighter in color Dentin tubules increase in diameter with depth toward pulp
Pulp in primary teeth
Larger than permannet teeth
Pulp horns closer to outer surface
Great variation in size and location
Mesial pulp horn is higher
Roots of primary teeth
Anterior roots are narrower MD than BL Molar roots are longer and more slender Roots more flared Roots branch directly from crown with no root trunk Larger apical formina Many accessory canals
Maxillary Central Primary Incisor Anatomy
MD crown width is greater than crown height
Square Tooth
Maxillary Lateral Primary Incisor Anatomy
Longer than maxillary central
Maxillary Primary Canine Anatomy
Wider, more symmetrical than mandibular canine
Cusp tip is offset to the distal
Maxillary 1st Primary Molar Anatomy
Greatest dimension is BL
4 cusps - 2 distal cusps are diminished
Maxillary 2nd Primary Molar Anatomy
Very similar to permanent counterpart
Can include cusp of Carabelli
Mandibular Central Primary Incisor Anatomy
Narrowest tooth MD
Straight incisal edge, very symmetrical
Mandibular Primary Lateral Incisor Anatomy
Wider and less symmetricalthan central
Rounded incisal edge
Mandibular Primary Canine Anatomy
Narrower than maxillary
Cusp is to mesial
Long distal slope
Mandibular Primary 1st Molar Anatomy
Wider MD than BL
2 mesial cusps are larger than distal cusps
Prominent “S-curve” of gingival tissues
Broad contact between mesial of of molar and canine
Mandibular Primary 2nd Molar Anatomy
Similar to permanent counterpart
Narrower BL and less pentagonal than permanent 1st molar
Objectives of Restorative Care
Restore damage caused by caries Preserve remaining tissue Prevent pain and infection Retain function Restore esthetics Facilitate good hygiene Maintain arch length
Sensitivity vs Specificity for caries diagnosis
Sensitivity: ability to determine caries when present
Specificity: ability to determine absence of caries when disease is not present
Visual, radiographic, laser fluorescence, fiber optic transillumination, electrical conductance, quantitative light-induced fluorescence have poor sensitivity and specificity
What is the best current method for caries detection?
Visual methods continue to be the standard for clinical assessment due to financial and practical reasons
Nonselective/Complete Caries Excavation
Carious dentin is completely removed at first visit
Stepwise caries excavation
Carious dentin is partly removed at 1st appointment with caries left over the pulp and temporary filling
Remaining carious dentin removed at 2nd appointment
Reduces pulp exposure compared to complete excavation
Partial/Incomplete Caries Excavation
Caries left over pulp with base and restoration placed in one visit
Reduces pulp exposures compared with complete excavation
More cost effective than stepwise excavation
OSHA requirements for materials
MSDS sheets need to be in a binder for any material that you have in your office
Epidemiology of pit-fissure caries
90% of caries in permanent teeth of children occurs in pits and fissures
2/3 occurs on occlusal surface alone
Primary teeth 44% occlusal caries
Is fluoride more or less effective on smooth surface compared to pits and fissures?
More effective on smooth surfaces
Primary, Secondary, Tertiary Prevention
Primary: intervention before evidence of disease (sealants)
Secondary: intervention after disease has begun, before symptoms (sealants)
Tertiary: intervention after disease is established (temporary sealant, PRR)
ADA Noncavitated/Initial Lesion Definition
Initial caries lesion development before cavitation occurs
Change in color, glossiness or surface structure as a result of demineralization before macroscopic break in tooth structure
Up to D1 lesion
Sealants can be placed on these lesions
Sealant success
Up to 76% reduction of incidence of occlusal caries
Risk of developing carious lesions in teeth with fully or partially lost sealants is no greater than teeth that have not been sealed
Sealed restorations superior to unsealed
Indications for Sealants
Caries-susceptible permanent molars -history of caries in primary molars -susceptible anatomy -poor oral hygiene Teeth that can be isolated
Resin Based Sealant Composition
Monomer: urethane dimethacrylate or bisphenol A-glycidyl methacrylate
Bis-GMA is product of bisphenol A and glyceryl methacrylate
Mechanism of adhesion of resin sealants
Mechanical
Wavelength of light for curing sealants
450-470nm
Camphorquinone/diketone-amine system
Minimal light output is 350
How do chemically cured sealants set?
By means of tertiary amine (activator) that is mixed with benzoil peroxide, producing free radicals that initiate polymerization
Compomer Sealants
Hydrophobic
Requires bonding agent
Fluoride release is low
Less retention than resin sealant
GI/RMGI Sealants
Suggested when isolation is difficult
Mechanical and chemical retention
GI versus Resin Sealants
GI has 5x greater risk of loss
GI has 3x greater risk of loss compared to RMGI
No difference in caries development with GI or resin sealant, but resin based has better retention
Indications for Sealant
Pit and fissure caries are questionable or in enamel only
Caries-free pits and fissures with at risk morphology
Medical history of xerostomia
Patient is receiving routine preventive dental care
Contraindications for Sealant
Caries extends into dentin Proximal caries or restoration involving pit and fissures Inadequate isolation Minimal or no caries risk Pit and fissure morphology not at risk Sporadic dental care
Reason for sealant failure
Most common from salivary contamination
Sealing over caries?
Acid-etch eliminates 75% of viable bacteria
Following sealant placement, dentinal lesions have been shown to be arrested
Retention of sealants over sound and carious tooth surfaces are similar
ADA Guidelines - Sealant Panel Recommendations
- Sealants effective in preventing and arresting pit-and-fissure caries in primary and permanent molars
- Sealants can minimize progression of non-cavitated occlusal carious lesions (initial lesions)
- Use of hydrophilic bonding layer enhances long-term retention
- Self-etching bonding agents provide less retention than total etch
- Routine mechanical preparation of enamel before etch is not recommended
- When possible, 4-handed technique should be used
- Use of explorers is not necessary for detection of early lesions
Is there a difference in sealant retention with air polishing versus conventional cleaning methods?
No
Rubber dam versus vacuum system isolation for sealants?
No difference
Rubber dam better than cotton
Does topical fluoride interfere with bonding between sealant and enamel?
No
Should you use adhesive with sealant?
Yes
Probably should cure it
BPA and Dental Materials
Dental materials contribute to very low level BPA exposure for up to 3 hours
Amount does not exceed FDA safe exposure limit
Limit by gargling with water, pumice on cotton ball, rubber prophy cup
PRR and CAR
PRR: Preventive Resin Restoration
CAR: Conservative Adhesive Restorations (reflects that other bonded materials like GI may be used)
Both involve removal of caries with sealant of adjacent pits/fissures
Resin Infiltration (ICON)
Can improve appearance of WSL May reduce lesion progression No preparation required No margin of restoration Not radiopaque
Components of resin infiltration
Icon dry: ethanol
Icon etch: 15% hydrochloric acid
Icon infiltrate: methacrylate based resin matrix, ignitors, adhesives
Indications for Resin Infiltration
Noncavitated E1-D1 lesions
WSL
Posterior and anterior use
