revision Flashcards
Dental adhesives:
Components:
resin monomers initiator system solvent fillers inhibitors
Dental adhesives:
Classified by:
Types of adhesive systems:
Classified by:
- generation
- adhesion
- combination
Types of adhesive systems:
Etch-and-rinse
Self-etch
Dental adhesives:
resin monomers:
forms and categories:
- hydrophilic in nature
- main component in adhesive systems and resin based composites
liquid form when placed in adhesive mixture
hard form after photopolymerization
2 categories:
- > functional (hydrophilic)
- contain a functional group that enhances wetting/demineralization of dentin
- > cross linker
- resists hydrolytic degradation
- interlocking with this
- better mechanical properties
Dental adhesives:
solvent:
ex:
functions:
Needs appropriate storage and handling otherwise restorations will fail
-> close the DBA bottle cause the solvent evaporates fast
ex: ethanol, water, acetone
Functions:
- > eliminates water molecules prior to curing of resin adhesive, without collapse of collagen fibrils
- > facilitate penetration of hydrophilic, small molecule resin monomers into the collagen meshwork of demineralized dentin
- > dissolves and reduces viscosity of monomers which results in simplifying transportation of monomers into demineralized collagen fibrils
Dental adhesives:
Fillers:
Functions:
-not always in dental adhesives
Functions:
- in low amounts they are used to increase mechanical properties
- prevent over-thinning of adhesive layer
- reduce shrinkage stress (produced during curing)
- provide radio-opacity
Dental adhesives:
initiator types:
photo-initiator (ex: camphorquinone (cq))
chemical-initiator
Dental adhesives:
ADV:
DISADV:
ADV:
- more conservative tooth preps
- antibacterial properties -> may prevent recurrent caries
- can treat root sensitivity
- increased R to recurrent caries
- increased R to caries in sealed fissure systems of posteriors
- reliable micromechanical retention to etch enamel w/o macro-retention features
- reinforcement of residual tooth structure
- stronger retention and increased R of glass matrix ceramic restorations fracture
- stable chemical adhesion to hydroxyapatite
- retain wide range of restorative materials
- expanded across different dental disciplines, not only operative dentistry
DISADV:
- marginal bacterial leakage
- post-operative sensitivity
- pulp inflammation or pulp necrosis
- enamel cracks
- moisture contamination
- contact dermatitis
- open contacts in posterior resin restorations
Dental adhesives:
generations:
1st generation -> 2 steps -> 2 components -> enamel etch 2nd -> 2 -> 2 -> enamel etch 3rd -> 3 -> 2-3 -> dentin 4th -> 3 -> 3 -> total etch 5th -> 2 -> 2 -> total etch 6th -> 1 -> 2 -> self-adhesive 7th -> 1 -> 1 -> self-adhesive 8th -> 1 -> 1 -> self-adhesive
4th generation uses 3 step E+R (so we use a separate step for etch and then rinse it off before applying primer and adhesive)
5th generation 2 step E+R (primer and adhesive are combined together)
6th generation 2 step SE (etch and primer are combined together)
7th generation 1 step SE (all in one bottle)
Resin based restorative materials:
ADV:
DISADV:
ADV:
- aesthetic appearance (main ADV over AMG)
- more conservative prep
- non-toxic -> no Hg release
DISADV: higher chance of: -fracture and failure of large restorations -secondary caries -marginal deficiencies -wear -post-operative sensitivity
Composite resins components:
3 organic components: resin matrix, silane coupling agent, initiator
Inorganic component: filler
-contain also inhibitors and pigments
Why we need to light-polymerize the bonding agent before the application of dental adhesives?
1) To obtain proper mechanical properties of adhesive
2) To ensure production of a thin layer of adhesive prior to composite application
How does polymerization occur?
CQ absorbs light and causes activation of amine co-initiators that produce free radicals
Hydrolytic degradation of hybrid layer components includes:
adhesives, collagen
Main goal of adhesive material is to achieve:
Tight and durable adaptation of restorative material to tooth structure
Enamel:
- densely mineralized
- brittle but hard
- not resilient
- dried
- the ideal substrate to form a tight adhesive joint
- micromechanical bonding (seals the restorative margins against leakage)
- more inorganic than dentin
- hydroxyapatite crystals: LARGER, more regular and arranged parallelly in enamel rods (92%)
Dentin:
- less brittle
- resilient
- similar at the nanostructural level to the bone (bone-like nanocomposite built of carbonated hydroxyapatite mineral particles, protein and water)
- COMPLEX BIOCOMPOSITE STRUCTURE
- humid (more water) and more organic than enamel (less inorganic than enamel)
- hydroxyapatite crystals: smaller and arranged in crisscross pattern in organic matrix
- no micromechanical interlocking (unlike enamel)
- dentin aging/carious lesion/aggressive stimuli cause physiological changes (ex: increase mineralization, dentin thickness and reduce permeability)
- reduction of permeability with age has a direct effect on dentin bond strengths, as dentin permeability affects the adhesion process
ETCH AND RINSE ADHESIVES:
ADV:
DISADV:
ADV:
- long track record (3-step ER)
- high immediate bond strength to enamel and dentin
- excellent bonding to enamel
- minor contamination with saliva doesn’t always decrease bond strength
- excellent results of clinical studies for 3 step ER
- ability to bond composite, porcelain, fiber posts, amalgam and etched or sandblasted metals
DISADV:
- acetone based adhesives need more applications than those recommended by manufacturers
- over-etching decreases bond strength
- more technique sensitive (than SE)
- 2 step ER undergoes degradation faster than 3 step ER
- bond strengths can VARY depending ON MOISTURE DEGREE
- more incidences of post-operative sensitivity with posterior composite restorations
- insufficient solvent air-drying recommended by manufacturers
SELF-ETCH ADHESIVES:
ADV:
DISADV:
ADV:
- long track record (2 step SE)
- EASY to apply (no etch or rinse)
- can be used with selective enamel etching
- contain hydrophobic bonding resin which PREVENTS DEGRADATION of resin-dentin interface
- less technique sensitive
DISADV:
- acidic primer not as acidic as phosphoric acid
- 1 step SE need more applications than those recommended by manufacturers
- 1 step SE can cause enamel leakage
- residual water may become entrapped if not properly evaporated which results in nanoleakage
- 1 step SE (HEMA-free) may compromise DURABILITY of enamel bonding
Bonding agents:
Components:
Etch -> to remove minerals, inorganic components (ex: hydroxyapatite in both enamel and dentin, leaving in dentin collagen fibers)
Primer -> contains solvent and monomer and attaches adhesive to tooth
Adhesive
components of resins:
Fillers:
Silane coupling agent:
Initiator:
Fillers:
enhance the strength and modulus of organic resin matrix
Silane coupling agent:
enhances tensile strength and bond strength of resin composite
Initiator:
polymerizes and crosslinks the composite into a hard form
->polymerization rxn can be triggered by light, chemicals or both
widely used monomer to construct composites:
Bis-GMA
Macrofilled self-cured composites DISADV:
- not used for posteriors bc of low wear R properties
- hand mixing
Composite modifications:
(a) curing modification
(b) filler modification
(c) resin modification
- macro
- micro
- hybrid
- universal
Microfilled composites – ADV:
higher polish ability and better color stability
Hybrid composites
ADV:
DISADV:
= combination of macro- and microfilled composites
ADV:
-improved wear R
-favorable mechanical and optical properties
DISADV:
esthetic
Universal composites:
ADV:
uses:
ADV:
- improved wear R
- improved mechanical properties
- maintain good polishability
- esthetic properties of microfilled composites
-used for both anteriors and posteriors
Classes of composites depending on consistency:
a) flowable
b) packable
flowable composites
ADV:
DISADV:
uses:
ADV:
-better adaptation in deep or undercut areas of cavity
DISADV:
-lower mechanical properties
uses: cavity lining small restorations load free areas (class V) restoration repairs
Failures due to improper light curing:
- time of light polymerization
- amount of energy delivered
- > improper position of light tip
- > thickness of resin
- > movement of light tip amid curing
- > separation of light tip from resin
- > shade and type of resin
- > state of light curing unit
Consequences of polymerization shrinkage stress:
- > is critical as a result of its impact on cavosurface edges
- > marginal gap
- > incremental filling techniques have been recommended due to this polymerization shrinkage
- post-operative sensitivity
- marginal staining
- recurrent caries
- eventual loss of restoration
Reducing the volume of composite that is polymerized at each stage of the restorative procedure:
- minimizes shrinkage
- maximizes the conversion conversion of monomers to polymer
Pre-warming of composites:
- increases composite flow
- marginal adaptation
- monomer conversion
- decreases system viscosity
- enhances radical mobility
- additional polymerization
- higher conversion
Factors influencing secondary caries:
1) caries risk factors
- saliva
- diet
- fluorides
2) restorative material
- placement technique
- surface properties and plaque accumulation
- bonding to tooth
- biodegradation
- antibacterial and buffering effect
3) restoration
- gaps and overhangs
- location
- size
- class
Posterior composite restoration – class ii success depends on which factors?
- patient selection/characteristics
- > high caries risk pts have 2x more failure rate than low caries risk pts
- > take in consideration the caries status of pt and adjust recommendations for restorative materials accordingly
- tooth prep
- > composite prep is more conservative
- > as the no of restored surfaces increases, the risk of restoration failure increases
- > tooth position influences the clinical performance and longevity of restoration (P lower failures than M)
- matrix use
- > reproduces good proximal contact, which minimizes food impaction and maintains healthy periodontal tissues
- > poorly done: open margin -> penetration of liquids
-composite composition-dentin bonding
C-factor:
= cavity - configuration factor
- ratio of bonded SA to non-bonded SA (needs to decrease)
- the higher it is the less chance for relaxation of polymerization shrinkage
- decreases bond strength
- we want it low
Why do premolars show less failures than molars?
bc the masticatory forces and stresses placed on Molar restorations are higher than those placed in Premolars
The position of tooth influences the clinical performance and longevity of restoration
Correct Matrix use/type:
- you create a good proximal contact which helps:
- minimize food impaction
- maintain healthy perio tissues
- avoid open margin (oral fluids go through)
- avoid marginal leakage -> most common reason for composite restoration failure
Improper isolation causes:
- decreased bond strength
- decreased physical and mechanical properties of composite restoration
self etch
Vs
etch and rinse
difference in etching:
self etch:
selective etching on enamel only for 15’’
bioactive restorative materials:
=
= elicit a response from living tissues/organisms/cells
- > ex: induce formation of hydroxyapatite
- macrofilled composites
- exhibit capacity to release bioactive agents
Inlay prep steps:
- 1,5 mm depth
- 2,5 mm depth
- Stop 1 mm from the nearest occlusal contacts
- Dovetail in the facial groove to enhance R+R
- Flat pulpal floor; perpendicular to path of insertion
- Proximal box: 1-2 mm supragingival
- Enamel hatchet to break undermined tooth structure
- Extend the box B and L where it will break contact with adjacent tooth
- Widen the isthmus where it joins the proximal box
- Proximal flare: cut equally B and L wall of the box and the outer surface of the tooth (gingiva: narrow, occlusal end: wider)
- Gingival beveling of 30-45 degrees to provide strength and marginal fit (flame bur for bevel)
- Occlusal beveling of 10-20 degrees at the junction of occlusal 1/3 and pulpal 2/3 of isthmus wall
Onlay prep steps:
- Functional cusp: 1,5 mm
- Non-functional cusp: 1 mm
- Facio-occlusal line angle: 0,5 mm
- Functional cusp beveling of 1.5 mm
- Occlusal shoulder finish line: 1 mm
- Lingual occlusal chamfer/shoulder finish line
- Isthmus: 1 mm shallower than inlay
- Proximal box should break contact with the adjacent tooth mesially
- Gingival floor: 1 mm
- Facial walls: diverge occlusally, Axial walls: converge occlusally
- Once proximal boxes are finished, flares are added
- Gingival bevel 0,5-0,7 mm
- Facial occlusal bevel 0,5 mm
- Lingual occlusal bevel of 0,5 mm on the occlusal shoulder
cariogram:
green: chance to avoid new cavities dark blue: diet red: bacteria light blue: susceptibility yellow: circumstances
PHTEN:
P: purpose H: health T: treatment E: evaluation N: next
radiographic examination - notes:
- type of x-ray
- quality of x-ray
- bone levels
- findings
- justification
main reason for bonded partial ceramic crown failure:
fracture
when does the susceptibility of ceramic inlay fractures increases?
when the cavity angle is increased by 5 -> 10 -> 20 degrees
a large internal cement space can cause:
- a higher polymerization shrinkage of luting cement
- less optimal support to ceramic restoration
non retentive Vs retentive preparation design for partial ceramic crowns:
a non retentive design increases the internal adaptation and marginal fit
- > the easier the restoration to be positioned on prepared tooth surface
- > the easier the cement will flow during seating and cementation
- > the more precise the occlusion
Conventional cements:
indications:
Vs
Adhesive cements:
types:
properties:
indications:
Conventional cements:
– Retentive conventional castings such as pfm and bridges or metal inlays/onlays
– Retentive tooth colored restorations that is indicated to be conventionally cemented (e.g. Zirconium oxide)
– METAL prefabricated or cast posts
Adhesive cements: types: 1. self etching resin cements 2. resin cements: -10-MDP -higher strength -types: dual, dual, light cure -bonding agent is required
– More technique sensitive – More difficult to use – More difficult to clean up – More expensive – More time consuming
– All ceramic restorations that require adhesive bonding (e.g. feldspathic porcelain veneers, inlays/onlays)
– Non retentive conventional castings (e.g. PFM crowns)
– Resin bonded bridges
– Non retentive natural tooth colored restorations (e.g. Zirconium oxide or lithium disilicate crowns)
– Posts of any type
conventional cements and their properties:
Zinc phosphate cement: • Very long successful track record • Low film thickness • Easy cleanup of excess cement • Good working time
Zinc polycarboxylate cement:
• Considered more biocompatible
• Not very strong
• More difficult to use than Zinc Phosphate
• Thicker consistency during mixing
• Low working time
• More difficult to clean up than zinc phosphate
Glass ionomer cement: • Biocompatible • Chemical bonding to dentin • Fluoride release • Stronger than zinc phosphate and zinc polycarboxylate • Should be protected from water for at least 10 min
Resin modified glass ionomer cement:
• May be less soluble and stronger than GIC
• Can be light cured
Self-Etch Approach
- No etching and no rinsing
- Smear layer is not removed
- More superficial interaction with dentin
- Etching of enamel is not adequate
Porcelain/Composite:
Metal:
microetching, HF-, Silane primer, Resin cement
microetching, metal primer, resin cement
caries categories:
sound surface:
- no visible caries
- icdas 0
initial stage caries:
- white spot lesion or brown discoloration
- icdas 1 and 2
moderate stage caries:
- brown spot lesion
- localized enamel breakdown w/o dentin exposure
- > icdas iii
- underlying dentin shadow
- > icdas iv
extensive stage caries:
- distinct cavity in opaque or discolored enamel with visible dentin
- icdas v and vi
- a WHO probe can confirm cavity extending into dentin
radiographic scoring system - ICDAS:
R0 R1 R2 R3 R4 R5 R6
R0 - no radiolucency
initial:
R1 - radiolucency in outer 1/2 of enamel
R2 - radiolucency in inner 1/2 of enamel
R3 - radiolucency in outer 1/3 of dentin
moderate:
R4 - radiolucency in middle 1/3 of dentin
extensive: -clinically cavitated -dentin is soft or leathery on gentle probing R5 - radiolucency in inner 1/3 of dentin R6 - radiolucency in pulp
signs:
active:
initial/moderate:
severe:
Vs
inactive:
initial/moderate:
severe:
active:
initial/moderate:
-enamel is whitish/yellowish, opaque, rough and matted on probing
-lesion covered by thick plaque prior to cleaning
severe:
-dentin is soft/leathery on gentle probing
inactive (arrested): initial/moderate: -enamel is whitish/brownish, shiny and smooth on probe severe: -dentin the same
-> you need to air-dry the tooth to check the lesion
ICDAS codes:
0 1 2 3 4 5 6
0
- sound tooth
- no tx
1
- first visual change in enamel
- F, OHI, debridement, icon, sealants
2
- distinct visual change in enamel
- F, OHI, debridement, icon, sealants
3
- localized enamel breakdown
- PRR and F, OHI, debridement, icon
- depends on caries risk assessment
4
- dentin shadow
- conservative tooth prep
5
- distinct cavity less than half of the tooth, with visible dentin
- restoration with filling
6
- extensive distinct cavity more than half of the tooth with visible dentin
- restoration with filling or crown
- > caries risk assessment
- > x-rays
single tooth isolation:
multiple tooth isolation:
isolation for class v restorations - subgingival lesion:
general rule:
single tooth isolation: class i class v sealants RCT
multiple tooth isolation:
class ii
multiple restoration and quadrant
bonding indirect restorations
isolation for class v restorations - subgingival lesion: retraction cord
general rule:
1 posterior and 2 anteriors
part of the old restorative material can be left in the tooth if:
- recurrent caries
- asymptomatic tooth
- base and liner periphery are intact
enamel beveling is required when:
- aesthetics
- increase SA
- better bonding
class iii access if always lingual unless:
- facial caries extension
- teeth are not straight and access is not possible
- too much removal of sound tooth structure will be needed
- old restoration extends facially
class ii - most difficult task to achieve:
tight proximal contact
selective caries removal:
small to moderate:
-removal until firm dentin (affected dentin)
moderate to large:
- removal until soft dentin (infected dentin)
- soft caries left over the pulp to avoid pulp exposure
pulp protection - bases and liners:
ex:
functions:
ex: MTA, Ca(OH)2, Biodentine
functions:
- protective physical and thermal barrier to the pulp
- allow healing and repair
- reduction of configuration factor (C-factor)
- reduction of shrinkage stress
indirect pulp capping:
tx for remaining dentin thickness:
2 mm
1-2 mm
0.5 mm
2 mm
-no tx, proceed with composite only
1-2 mm
-GIC or RMGIC
- 5 mm
- Ca(OH)2 and then GIC or RMGIC
direct pulp capping:
- wash cavity with sterile saline
- control the hemorrhage
- once bleeding stops
- place MTA/Ca(OH)2
- then place GIC/RMGIC
- proceed with restoration
->if bleeding doesn’t stop: RCT
post-operative instructions after amg restoration:
- wait until anesthesia wears off
- pt may experience post-operative sensitivity to hot or cold for a few days
- pt should not chew on the side of the new restoration for at least 12hrs
- pt should not chew anything for at least 2hrs
best to worst dentin bonding agents:
- 2 step SE
- > etch enamel only, primer bottle, dry, bond bottle, dry, lc - 3 step E+R
- > etch, primer a and b mix, dry, bond, lc - 1 step SE
- 2 step E+R
- > clinics
ideal properties of bonding agent:
- low technique sensitivity
- strong enamel acid etching w/ H3PO4
- mild dentin self-etching, for self-etching bonding agents
- to have final hydrophobic layer
- not to be acidic after light curing to avoid hydrophilicity
- to be dual cure
- to contain the powerful monomer 10-MDP
2 step self-etch steps:
-etch ONLY enamel for 30’’
-rinse for 10’’
-dry (not totally)
-PRIMER BOTTLE: primer added to the entire cavity with a microbrush - as well as dentin
-dry (gently and not totally)
BOND BOTTLE: bond added to the entire cavity with a microbrush
-dry (not totally)
-light cure for 20’’
-restoration
3 step etch and rinse steps:
- etch enamel for 30’’ and dentin for 15’’ w/ H3PO4
- rinse
- dry (not totally)
- mix primers A and B and apply them
- dry
- bond applied on enamel and dentin
- light cure for 20’’
- restoration
2 step etch and rinse steps:
- etch enamel for 30’’ and dentin for 15’’ w/ H3PO4
- rinse
- dry (not totally)
- apply bond in 2 layers
- dry
- light cure for 20’’
- restoration
sealant placement steps:
- isolation with rubber dam
- clean occlusal surface
- wash and dry surface
- etch w/ H3PO4 for 30’’
- rinse for 10’’
- dry
- optional for bonding
- flowable composite
- explorer
- light cure for 40’’
- check occlusion with articulating paper
-> for PRR use bonding agent, dry (leave moist) and then LC for 20’’
enameloplasty for aesthetics:
- always w/o anesthesia
- at the 1st sign of pain you stop to avoid sensitivity and need restoration later
air abrasion:
indications:
indications:
- stain removal
- debriding pits and fissures before sealing
- micromechanical roughening of surfaces to be bonded
- repair to more aggressive procedures like tooth prep
- > to excavate caries
- > pain free
- > no drill
- > no contact preparation method
gold onlay rules:
- no undercuts
- sharp angles to be avoided to prevent stress and crack propagation through the restoration
- accessibility of subgingival margins
- absence of contact b/w cavity and adjacent teeth
- adequate interocclusal space in centric and during lateral movements
- tooth prep to remain in enamel where possible
- sufficient thickness for technical construction
- smooth transition b/w tooth prep and restoration
- restoration margins not to be under occlusal load
- detailed sharp margins
ceramic onlay rules:
- no sharp edges or corners
- adequate sharp margins
- adequate uniform thickness of restoration
- simple cavity design w/ basic geometry
- avoid high tensile stress
- avoid stress peaks and sudden changes in cross-section
- minimize notch stresses
- make as large as possible contact surface with ceramic restoration
- enamel bordered restoration margins facilitate a stable and adhesive bond of ceramic restoration
gold onlay Vs ceramic onlay:
gold onlay: ADV: -biocompatible -rare allergies -soft material so kind to opposing teeth -long term longevity (more survival time than ceramic) -easy to work with -wide range of indications DISADV: -expensive -poor aesthetics
Ceramic onlay: ADV: -biocompatible -wear R -cheaper than gold -aesthetics DISADV: -more likely to have allergies than gold -less survival time than gold
Indications for onlays and inlays:
- post endo restoration -> RCTed teeth
- to correct occlusal plane of a tilted tooth
- broken down teeth with intact B and L cusps
- MOD restorations with wide isthmus
- teeth with risk of fracture
partial crowns Vs crowns:
partial crowns:
- better perio health
- preserves of tooth structure
- less endo complications
- better bonding
Biomechanical reasons that a heavily restored M1 can break:
- unsupported cusps
- insufficient or excessive beveling
- heavy occlusal forces
- bad prep design
Carious dentin zones:
soft (infected)
- cannot self repair
- easily excavated with hand and rotary instruments
- irreversibly denatured collagen
- severe bacterial contamination
leathery:
-transition from soft to firm
firm (affected)
- demineralization
- collagen intact
- R to hand excavation
hard
- includes: 3ry, sclerotic, normal dentin
- removed only with burs or sharp cutting instruments
Composite:
indications:
contraindications:
indications:
- class I, II, III, IV, V restorations
- core build ups
- sealants or PRR
- esthetic restorations
- temporary restorations
- veneers
contraindications:
- no moisture control
- high caries risk
- poor OH
- uncompliant patient
- heavy occlusal contacts restorations
Amalgam:
indications:
contraindications:
indications:
- patient with mental disabilities
- core build up
- posterior restorations
- no moisture control
- class II and V
- pin retained restorations
- heavy occlusal contacts restorations
- large amount of tooth structure missing
contraindications:
- anterior restorations
- class I, III, IV anterior
- small restorations
Proximal contacts – importance:
- prevent food impaction
- protect soft tissue from perio disease
- premature restoration failure
- prevent caries
- accessible to clean
High caries risk patient:
- too many carious lesions
- drinks many soft drinks/juices
- frequently eats sweets
- bad OH
- lost teeth due to caries
- inadequate salivary flow (xerostomia)
wingless clamps:
- provide more space for matrix bands and wedges
- bear a W before their number
safe removal of amalgam:
- The use of Rubber Dam isolation
- High volume air evacuation
- Use of special burs and equipment to minimize aerosols
ideal properties of bases and liners:
- friendly to the pulp
- radiopaque (visible on x-ray)
- easy to mix
- easy to clean
- rapid setting
- high tensile strength
- bonding to dentin
IRM:
- to check if the patient has any symptoms
- stays for 3m
- patient comes back, use the cold test and check if patient is symptomatic or not and then remove it
a) -patient is asymptomatic - remove half of it and then place amalgam
b) -patient is symptomatic
- remove all of it
- and then bond and use composite
flowable composites:
polymerization shrinkage risk so don’t fill the whole cavity with it
Common Causes of Teeth Sensitivity:
- Brushing too aggressively and with hard bristles
- Consuming too much highly acidic food and drink
- Poor OH (leading to gum disease and tooth decay)
- Gum recession (leaves your root surfaces exposed)
- Grinding teeth
Ideal Post Properties:
- Minimal preparation required for post space
- Not technique-sensitive
- Biocompatible
- Resistant to fracture
- Retrievable
- Similar mechanical properties to dentine
- Aesthetic
- Radiopaque
- Inexpensive
