TOOTH CONS Flashcards
What are the principles of cavity design?
Access form - simples direct route to caries
Outline form - dictated by anatomy and peripheral caries
Resistance form - preventing fracture of the tooth and restoration
Retention form - preventing displacement of restoration in all possible directions
Convenience form - adeqaute shape and size of cavity for instruments and materials
Removing remaining carious dentine
Completing cavosurface angle
Cavity debridement
What are the indications for placing a fissure seal
Non-carious posterior teeth with deep retentive fissures
Early permenent dentition at high risk of caries (within 2-4 years of eruption)
Posterior teeth with minimal evidence of staining or a non-cavitated lesion
A young patient attends your surgery with recently erupted lower 6’s, this patient is a high caries risk, which of the following is the optimal tx?
A. Do nothing, reinforce OH
B. GIC restoration
C. Flowable composite resin fissure seal
D. GIC fissure seal
D - the patient is a high caries risk; FS is indicated
The newly erupted tooth will create limitations in the FS due to moisture control issues and because of this GIC is the recomendation over a resin-based material
Define each of the black’s classifications
Class I - occlusal surfaces, occlusal 2/3 of buccal or lingual surfaces on posterior teeth, palatal surfaces of upper anterior teeth
Class II - proximal surfaces of posterior teeth
Class III - proximal surfaces on anterior teeth
Class IV - proximal surfaces on anterior teeth, involving and incisal corner
Class V - gingival 1/3 of buccal and lingual surfaces of anterior and posterior teeth
What are 6 benefits of using rubber dam
Medicolegal - preventing ingestion/inhalation of materials and/or instruments
Patient safety - prevention of aspiration of fluids/instruments, protection of soft tissues
Aseptic - preventing salivary contamination
Access - visual field is improved
Patient comfort
Reduced aerosols - less cross-contamination
Which clamp would you use on a 26
A. 00
B. 9
C. 7A
D. 2A
C - This is a molar clamp
other molar clamps –> 8A, 14A, 26N, 27N & 56
A & B are anterior clamps
D is a premolar clamp
Why does the progression of a carious lesion reaching dentine result in unsupported enamel?
Caries begins in the enamel and travels down towards the DEJ, once at the DEJ the carious lesion spreads laterally –> the undermining of DEJ and lateral spread then results in cavitation as the enamel becomes weakened/unsupported
- taken from a DMD1 quiz
What is the difference between a simple, compound and complex cavity prep?
Simple - involves 1 surface
Compound - involves 2-3 surfaces
Complex - involves 4+ surfaces
Define cavosurface angle
The angle between a prepared wall and the external tooth surface
What are the cavity dimensions of a conventional class III cavity for CR?
Height - 3-3.5mm height (labial wall)
- 0.5-1mm into proximal region
Width - half-way across palatal ridge
Depth - atleast 1/2 way across the proximal surface
In which cavity design for CR would you add a labial bevel, a chamfer and a gingival bevel?
Class IV
Which of the following is most true about amalgam?
A. A high copper amalgam has a gamma 2 and eta-phase
B. A low copper amalgam contains = 15% Cu
C. A high copper amalgam is more succeptible to erosion
D. The gamma 1 phase of both high and low copper amalgams is Ag2Hg3 (silver mercury)
D
A - high copper amalgam does not have a gamma 2 phase
B. low copper amalgam contains = 5% Cu
C. low copper amalgam is more succeptible to corrosion because of the gamma 2 phase (tin/mercury)
What does ‘creep’ refer to in amalgam restorations
creep is the plastic deformation of the material under a constant low-level load
High-copper amalgam has less creep
How does amalgam self-seal?
microleakage –> causes corrosion –> corrosive product accumulation att the surface/interface of restoration and cavity –> reduced microleakage
Which of the following is most correct regarding pulpal protection
A. Moderate cavities where 1-1.5mm of dentine remains do not require a GI liner/base
B. MTA and Biodentine are examples of calcium silicate cements which can be used as pulpal protection
C. Deep cavities where <0.5mm dentine remains require a Ca-hydroxide liner only
D. Ca-hydroxide OR calcium silicate cement can be used as a base in deep cavities
B
A - these cavities DO require a liner/base
C - these cavities require a liner (pulpal protection such as Ca-hydroxide) and a base
D. these are materials for pulpal protection and are used as liners, not as a base
You triturate (mix) your amalgam and once you open the capsule and dispense it into a dappen dish it looks dull, grainy and crumbly. Did you;
A. over-triturate
B. mix correctly
C. under-triturate
C. under-triturate
If its mixed properly it will appear shiny and plastic
If its over-triturated it will have a high shine, be hot and sticky
What is the difference between ‘finishing’ and ‘polishing’ an amalgam restoration?
Finishing - removing macroscopic irregularities
Polishing - removing microscopic irregularities
Discuss the setting reaction of GIC’s
MIXING: acid-base reaction –> acid attacks the glass network resulting in aluminium, calcium and fluoride
20-40 seconds
INITIAL SET: decomposition and gelation –> cations form salt bridges (calcium-polyacrylate) which forms a silica hydrogel
3-6 minutes
MATURATION: aluminium-polyacrylate linkage
24hrs+
Match the type of GIC with its function
A. Luting/Bonding cement: crown cementation and root canal sealing
B. FS, liner/base
C. Restorative
Type I, Type II, Type III
Type I - Luting/Bonding
Type II - Restorative
Type III - FS, liner/base
Give the specific name to the following instruments;
A. probe with 1mm incremental markings
B. probe with incremental markings of 3, 2, 3, 3 (no ball tip)
C. explorer probe
D. cylindrical double sided instuments used to condense amalgam
E. triangular/cone shaped double ended instument used to place/push composite resin into tight proximal boxes
A. CP-15 B. CP-11 C. #6 Explorer D. #153 amalgam packer E. Westco Mortenson packer
Describe phase 1 and 2 of resin bonding to the tooth surface (ie. what is happening at the tooth surface in etching and bonding)?
Phase 1 –> creation of microporosity in enamel and dentine by removing superficial hydroxyapatite
Phase 2 –> resin infiltration and in situ polymerisation within the created microporosities (hybridisation)
What is the primary mechanism of adhesion?
Micromechanical interlocking in the hybrid layer
Which is the correct protocol for bonding
A. phosphoric acid treatment of enamel margins only, wash/dry, application of prime&bond, air thin, light cure
B. phosphoric acid treatment of enamel margins only, wash/dry, application of self-etch prime&bond, air thin, light cure
C. phosphoric acid treatment of enamel and dentine, wash/dry, application of self-etch prime&bond, air thin, light cure
B
A - treating the enamel margins only is a self-etch technique, the dentine still requires an etchant and for this you would need to use a self-etching primer
C - this is a total etch techique of enamel and dentine, you would not need to use a self-etch primer here
What are the main components of dental composites
Organic matrix - BisGMA, UDMA, TEGDMA
Inorganic filler - modified silica glass particles
Silane (coupling agent)
Describe the curing reaction of CR
Initiation –> initiator becomes excited/activated by the light energy –> interaction and activation of monomers
Propogation –> activated monomers bind to other monomers forming polymer chains
Termination –> growing chains bind to other polymer chains –> complete polymerisation
Which of the following has the best aesthetic properties?
A. Macrofill CR
B. Amalgam
C. GIC
D. Microfill CR
D
Which of the following is most correct
A. degree of conversion is the percentage of C=C double bonds converted to C-C single bonds in polymerisation, this should always reach 100%
B. Universal composites shrink around 10%
C. Shrinkage stress is the tension at the composite-tooth interface
D. The greater the C factor the less stress development
C
A. this is mostly correct but it never reaches 100%
B. universal composites normally shrink 2-4%
D. the greater the C-factor the greater the stress
Which of the following is incorrect about CR
A. Elastic modulus is the stiffness of a material and this correlates with inorganic filler content
B. In an abfraction lesion a material with a low elastic modulus is ideal
C. The more filler content in CR the more translucent
D. The more filler content the better the mechanical properties
C - the more filler content the more opaque the material
What is the wavelength range of dental curing lights?
400-500nm
At what thickness can CR be cured adequately
At what thickness can bulk-fill CR be cured adequately
2mm
4-5mm
You have a large cavity (>4mm) and you are planning to use a bulk-fill composite, what process will achieve the best outcome
A. Using a fibre reinforced bulk fill for the entire cavity
B. Using a flowable bulk-fill for the entire cavity
C. Using a sculptable bulk fill in two increments, the lower layer <4mm
D. Using a sculptable bulk fill in two increments the lower layer being 4mm and the upper layer being <4mm
C. - this is ideal as the lower layer is harder to reach with the light so a thinner increment will have increased potential for complete cure at that depth
A. fibre-reinforced has excellent mechanical properties but the glass fibres cannot be polished so this would require a capping layer
B. Flowable bulk fill MUST be covered with a sculptable bulk fill
D. as above, a 4mm layer at the base increases the risk of inadequate curing
Differentiate between a liner and a base
Liner - a fluid paste-type material used on pulpal/axial walls in 0.5-1mm increments to create a protective barrier between the dentine and restorative material
Base - as above except >1mm increment beneath a final restoration
What are 5 objectives of a liner/base
pulpal protection remineralise caries-affected dentine provide adequate cavity geometry for AR block undercuts chemical bond to dentine --> reduce microleakage restore lost dentine --> base stress relief during CR shrinkage resistance during AR condensation
You need to etch the dentine with phosphoric acid prior to placing a therapeutic agent
True/False
False
In an open sandwich technique it is ideal to place the GIC below the contact point
True/False
True - GIC is prone to proximal defect if its in contact with the adjacent tooth
Select the most correct answer regarding liners/bases
A. GIC liner is recomended below all ARs
B. eugenol-based materials can be used as a liner/base under resin based materials
C. flowable composites are superior to GIC as a liner
D. You only need a therapuetic agent if you expose the pulp
A
B - eugenol-based materials adversely affect resin polymeristation
C. no evidence to show flowable is better than other liners
D. You want a therapeutic agent in any deep cavities where you may be near the pulp - a pulp exposure will require a directy pulp cap with calcium-silicate cements (MTA/Biodentine)
What is the common name for zinc-oxide sulphate cement
Cavit
What level of reduction would you need to do in order to cusp cap
2mm
Select the most correct answer regarding complex composite restorations
A. Composite is the material of choice in a complex restoration
B. A cusp is defined as weak when the occlusal outline extends more than 2/3 from primary groove to cusp tip
C. Complex CR restorations are long-term solutions
D. Flowable and sculptable bulk-fill are recomended for cusp replacement/protection
B
A. Indirect restorations are more ideal and amalgam is the material of choice in direct, but CR is often selected due to aesthetics, efficiency and conservative properties
C. complex CR’s are a medium-term solution
D. Highly-filled (>/=74%) universal CRs in 2mm increments are the composite resins that are recomended
Explain why the endodontically treated tooth is weaker?
Altered dentine –> from irrigant and dressing tx
Reduced tooth structure –> significant removal in tx
Reduced proprioception –> sensation removed = higher loads applied without the patient awareness
Decreased moisture –> there is a small degree of dehydration 5-12% but this is not a key issue
Which of the following is correct regarding restorations of endodontically treated teeth?
A. anterior and premolar teeth should have a post if there is 30% or more tooth structure lost
B. A ferrule can be a mix of restoration and tooth structure
C. A ferrule increases the resistance form of an indirect restoration
D. GIC can be used as a core material
C
A - >50%
B - must be all tooth structure
D - core material should be amalgam or CR
Discuss the steps in restoring a tooth, from access –> finishing restoration
- Establish outline at optimal depth
- direct simplest access to caries, removing peripheral caries in enamel, the DEJ and 0.5mm of dentine
- freedom from contact
- outline beyond fissure system - Satisfy retention, resistance and convenience form
- Remove deeper caries
- from periphery to deepest region
- using large slow speed bur and tactile sensation - Complete the cavity
- adjustments to cavity margins, removing weakened enamel, debridement - Place a liner or therapeutic IF needed
- Matrix selection and placement
- Bonding procedure
- total etch (three step, two step)
- self-etch (two step, one step)
- selective etch (three step, two step) - Place restoration
- Finish restoration
Name 3 indications and 3 contraindications for a veneer?
Probs the only q they will have for simple composite veneer.
• Indications:
o Inadequate tooth colour that does not respond to any whitening method
o Unsatisfactory tooth shape and/or position
o Inadequate tooth size
o Diastemas
o Partial tooth crown fracture
o Gummy smile
• Contraindications: o Bruxism o Bad habits (e.g. nail biting) o Weak support Teeth with big fillings ETT without intraradiculat posts o Unrealistic expectations o Bad OH
What are the four exceptions to palatal access for a class III?
- Irregular alignment of teeth
- Caries positioned towards labially (tooth tissue preservation)
- Extensive caries involving labial surface
- Old restoration placed labially
- If you’re the too-big-for-her-boots OHT at ashleigh’s workplace
When to place a palatal bevel vs palatal chamfer?
Palatal bevel indicated when outside of occlusal contact area and palatal chamfer indicated when in occlusal contact area.
Which of the following is true?
A) Lathe cut amalgam alloy requires less force on condensation
B) Low copper amalgam < 12% copper
C) High copper amalgam increases gamma 1 phase
D) Spherical cut amalgam alloy requires less force on condensation
D)
What are the two types of resin-based fissure sealants and which one is recommended?
Filled: Filler particles only have a small impact on the outcome of the fissure sealant and reduces ability of the penetration into the fissure sealant. Filled fissure sealant generally require more occlusal adjustment.
Unfilled: Low viscosity allows better penetration into the fissure and lower microleakage rate. Occlusal adjustments generally not required.
Briefly explain how resin penetration occurs in the enamel and dentine in etch and rinse strategy.
A) Enamel
- Macro tags = Resin penetrates adjacent enamel prisms
- Micro tags = Resin penetrates individual HA crystals
B) Dentine
- Adhesive layer = Complete zone of demineralisation with only resin
- Hybrid layer = Complete demineralisation of inorganic material but collagen remains - penetration of resin around these collagen fibrils
- Resin tags = Penetration of resin into the dentine tubules
Distinguish CaOH and CaSilicate as therapeutic agents, which is indicated for direct and indirect pulp exposure?
CaOH = Indirect pulp capping
- Less expensive
- More soluble
- Stimulate tertiary dentine (dentine bridge) irregular, porous, cellular inclusions
- Inferior marginal adaption
CaSilicate = Direct pulp capping
- More expensive
- Less soluble
- Stimulate tertiary dentine (dentine bridge) homogeneous, tubular, less cellular inclusions
- Better marginal adaption
- May discolour tooth (bismouth oxide)
What are 4 objectives of a therapeutic agent
Pulpal protection (isolation)
Tertiary dentine formation
Remineralisation of caries affected dentine
Reduction of bacterial count
