Luting Agents Flashcards
what effect does particle size have on viscosity
smaller particles means less viscous
what effect does glass particle size have on translucency
larger particles are more translucent
maximum film thickness for luting agents (max particle size)
25um
should be low so that it doesn’t interfere with seating of restoration
ideal viscosity of luting agents
should be low to allow seating of restoration without interference
describe the ideal marginal seal of a luting agent
luting agent would ideally chemically bond to both the tooth and the indirect restoration creating a permanent impermeable bond
(some new materials are approaching this)
what is the ideal conductivity of luting agents
ideally want a low thermal conductivity
think metal crowns - don’t want heat transfer towards pulp
why might zinc phosphate, a dental cement, still be used nowadays
may be used to cement temporary restorations as it doesn’t stick to tooth and can be easily removed using an ultrasonic
cons of dental cements
(zinc phosphate and zinc polycarboxylate cement)
low pH
exothermic setting reactions
no/ minimal bond to tooth
not cariostatic.
what is the main difference between glass ionomers used for restorations and those used as luting agents
luting agent GIs have smaller particle sizes (<20um) to achieve a suitable film thickness
how do GIs bond to tooth
exchange of calcium with enamel and dentine and hydrogen bonding with the collagen in dentine
GI luting cements cannot bond to restorations, how is this overcome
by sandblasting the fitting surface of indirect restorations so mechanical adhesion can be achieved
Do GI luting agents require any etch and bond
no
why cant resin modified GIC’s be used under porcelain or to cement posts
presence of HEMA means it has the potential to swell in wet environments so risks cracking porcelain
pros and cons to using resin modified GICs over conventional GICs for luting agents
pros to resin: shorter setting time, longer working time, less soluble, better bond to tooth
cons to resin: presence of HEMA which may expand in wet environments and also may be toxic to pulp if not fully polymerised
Name 2 drawbacks to composite luting agents
require a dentine bonding agent, unlike GICs
technique sensitive - area must be dry - not suitable for subgingival crown margins?
advantages to composite luting agents compared with resin and conventional GICs
better physical properties
better aesthetics
lower solubility
where is a dentine bonding agent required when using a composite luting agent to cement a indirect composite restoration
DBA required between the tooth and the luting agent
the luting agent will micromechanical bond to the indirect restoration (internal surface roughened for mechanical bond, C=C bonds remain for forming chemical bond)
what two agents are required when bonding porcelain using composite luting cements
dentine bonding agent - to bond luting agent to tooth
silane coupling agent - to bond luting agent to porcelain indirect restoration
why are fitting surfaces of metal indirect restorations sandblasted rather than etched to achieve a roughened surface that luting agents can bond to even though etching produces a better result
etching is technique sensitive and precious metals cant be etched
etching works best on alloys containing berrylium which is a carcinogen
why is a dual curing composite resin luting cement required for bonding indirect metal restorations rather than light cure
light wont be able to penetrate through the metal
what luting agent could be used for cementing a MCC and what makes this good
Panavia 21
anaerobic self cure and self adhesive resin cement
Contains MDP to bond to metal
(self cure i.e no light needed as light cant penetrate metal)
what two agents are required when bonding metal indirect restorations with composite luting agents
dentine bonding agent - between tooth and luting agent
metal bonding agent - between luting agent and restoration
what might be contained within temporary cements to weaken the structure of the set cement meaning easier removal
carnauba wax
petroleum jelly can also be added
what are the two main types of temporary cement and what are the contraindications for one
either with or without eugenol
if forthcoming luting agent contains resin , eugenol free temporary cement should be used to prevent interference with setting
self etching composite resin luting agents
- results in comparison to conventional composite agents
- price
- use of DBA
- poorer results compared to conventional composite resin luting agents
- expensive
- dentine bonding agent contained within the luting agent
Dual cure composite luting cement
- brand example
- do i need DBA
Nexus universal
yes, DBA needed
what is aquacem
GIC luting agent
What is an example of a RMGIC for luting
RelyX luting
