06/04 Flashcards
Role of fluoride
- incorporates into tooth to form fluoroapetite, which is more caries resistant than hydroxyapetite
- inteferes with adhesion of bacteria
- promote remineralisation
- make enamel more resistant to acid
How to identify caries?
- clinical detection
- dry tooth
- good light
- sharp eyes
- fibreoptic transillumination
- caries detection dye
- radiographs
- sensibility and vitality test
7 caries risk assessment (SIGN 47)
- medical history
- social economical status
- salivary flow
- fluoride use
- diet
- clinical evidence
- plaque control
Biofilm development
- adhesion/ attachment - bacteria attach to the pellicle via fimbriae, this is initial reversible adhesion
- colonisation- primary colonisal provide new binding sites for adhesion by other oral bacteria, firm irreversible anchorage
- maturation- development of micro-colonises and eventually to a mature biofilm
- climax community
- dispersal- dispersal of microbes to
Fluoride toxicity
- fluorosis
- impaired growth of apatite crystals
- retain matrix proteins
- increase binding of proteases
How does calcium fluoride work?
- high fluoride content in the mouth, from calcium fluoride
- acts as fluoride reservoir
- works fluoride varnish is applied
Fluoride reservoir
- calcium fluoride
- fluoroapatite
Fluoride
- fluoride varnish
- fluoridated water
- fluoride toothpaste
- fluoride MW
- Toothmousse
What’s in Toothmousse?
CPPACP
- casein phosphopeptide amorphus calcium phosphate
- cannot give pt who is lactose intolerant
Roles of fluoride
- incorporation into enamel crystal to form fluroapetute
- resistant to streptococcus strains
- inteferes with adhesion force of bacteria, reducing ability to stick to surface of tooth
Does fluorosis happen in adults?
- only occurs during development of tooth
- resin infiltration
- ## direct restoration
Toothpaste fluoride toxic dose
- 5mg/kg
Management of fluoride toxicity
BDS 2 lecture
- drink milk
- monitor for a few hours
- IV calcium gluconate (15-64 admit to hospital)
Cavity design of amalgam
- undercuts
- convergent occlusally
- 90-120 degree cavosurface margin angle, buttjoint
- cavity depth 2mm
- isthmus 1-1.5mm, 1/3 width of tooth
Increase retention of amalgam
- undercut
- retentive groove
- dovetail
- reverse s curve
- dentine pin
- metal bonding agent
Cavity design of comp
- bevel joint
- no undercut
- no unsupportive enamel
- no excessive acute angle
- rounded internal point angle
- depth 1-1.5mm
- margin clear of occlusal contact
If caries left at ADJ and restore?
- enamel at ADJ is weak and may break down restorative margin
- unsupported enamel
- marginal integrity is compromised
- caries will spread laterally and towards pulp
Amalgam constituents
- mercury
- silver
- tin
- copper
- zinc - scavenger during production, oxidises and slag formed
Two types of amalgam
- traditional amalgam
- copper enriched amalgam (13-30%)
Gamma 2
GAMMA 2
- weak and poor corrosion resistance
- thin mercury
What is creep?
- when a material is repeatedly stressed for a long period at low stress levels (stress below elastic limit), it may flow, resulting in permanent deformation
- ditching margins
Benefits of Copper enriched
- higher early strength
- less creep
- higher corrosion resistance
- increased durability of margins
Indication of amalgam
- large cavity
- moisture control cannot be achieved
- bruxism patients
- if aesthetics is not a concern
- cheaper
Contraindication of amalgam
- allergy to metal
- contact allergy
- aesthetic
- breast feeding
- under 15 years old
- less conservative
Composite
- aesthetics
- bond to teeth
- can add on
- low thermal conductivity compared to amalgam
- high compressive strength
- biocompatible
- bonds to dentine
Contraindication of composite
- more expensive
- monomer leaching
- stain
- higher polymerisation shrinkage
- exothermic reaction cause pulpal irritation
- curing 2mm
Constituents of composite
- Filler particles, glass, ie: quartz/ silica (increase tensile strength, increase hardness, reduce polymerisation shrinkage)
- photoinitiator, camphorquinone
- Bis-GMA
- low weight dimethacrylates
- HEMA
- silane coupling agent
Etch and bond
- etch to roughen surface and remove smear layer from dentine
- create micropores for micromechanical retention
- prime and bond to create an adhesive layer for composite to bond to tooth surface
- bond has Bis-GMA and form hybrid layer with collagen network
What does primer do?
- penetrate in dentinal tubules
- hydrophilic and hydrophobic end
Dental cement uses
- luting agent
- cavity sealers
- protection of pulp
- ## cementing post and core
RMGI/ GI
- for non- load bearing area
too much etch and dry
- dentinal tubules collapse
Differences of RMGI and GI
- RMGI has resin
- RMGI has higher compressive strength
- better aesthetics
- better bond to tooth
self cure
- conventional GI
light cure
- RMGI, ie: RIVA
Disadvantages of RMGI
- monomer leakage
Fluoride varnish reduce dentine sensitivity
- block dentinal tubules
- fluoroapatite
- calcium fluoride
Colophony resin in fluoride varnish
- hardens in contact with saliva and allows longer retention of fluoride varnish on tooth surface
what to do after internal bleaching and shade match?
Reverse acidity with Ultracal before white GP
Medical contraindications to whitening
- G6PD deficiency
- Acatalasemia
- they cannot metabolize hydrogen peroxide
