Luting Agents

Question 1

what effect does particle size have on viscosity

Answer 1

smaller particles means less viscous

Question 2

what effect does glass particle size have on translucency

Answer 2

larger particles are more translucent

Question 3

maximum film thickness for luting agents (max particle size)

Answer 3

25um
should be low so that it doesn’t interfere with seating of restoration

Question 4

ideal viscosity of luting agents

Answer 4

should be low to allow seating of restoration without interference

Question 5

describe the ideal marginal seal of a luting agent

Answer 5

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)

Question 6

what is the ideal conductivity of luting agents

Answer 6

ideally want a low thermal conductivity
think metal crowns - don’t want heat transfer towards pulp

Question 7

why might zinc phosphate, a dental cement, still be used nowadays

Answer 7

may be used to cement temporary restorations as it doesn’t stick to tooth and can be easily removed using an ultrasonic

Question 8

cons of dental cements
(zinc phosphate and zinc polycarboxylate cement)

Answer 8

low pH
exothermic setting reactions
no/ minimal bond to tooth
not cariostatic.

Question 9

what is the main difference between glass ionomers used for restorations and those used as luting agents

Answer 9

luting agent GIs have smaller particle sizes (<20um) to achieve a suitable film thickness

Question 10

how do GIs bond to tooth

Answer 10

exchange of calcium with enamel and dentine and hydrogen bonding with the collagen in dentine

Question 11

GI luting cements cannot bond to restorations, how is this overcome

Answer 11

by sandblasting the fitting surface of indirect restorations so mechanical adhesion can be achieved

Question 12

Do GI luting agents require any etch and bond

Answer 12

no

Question 13

why cant resin modified GIC’s be used under porcelain or to cement posts

Answer 13

presence of HEMA means it has the potential to swell in wet environments so risks cracking porcelain

Question 14

pros and cons to using resin modified GICs over conventional GICs for luting agents

Answer 14

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

Question 15

Name 2 drawbacks to composite luting agents

Answer 15

require a dentine bonding agent, unlike GICs
technique sensitive - area must be dry - not suitable for subgingival crown margins?

Question 16

advantages to composite luting agents compared with resin and conventional GICs

Answer 16

better physical properties
better aesthetics
lower solubility

Question 17

where is a dentine bonding agent required when using a composite luting agent to cement a indirect composite restoration

Answer 17

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)

Question 18

what two agents are required when bonding porcelain using composite luting cements

Answer 18

dentine bonding agent - to bond luting agent to tooth
silane coupling agent - to bond luting agent to porcelain indirect restoration

Question 19

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

Answer 19

etching is technique sensitive and precious metals cant be etched
etching works best on alloys containing berrylium which is a carcinogen

Question 20

why is a dual curing composite resin luting cement required for bonding indirect metal restorations rather than light cure

Answer 20

light wont be able to penetrate through the metal

Question 21

what luting agent could be used for cementing a MCC and what makes this good

Answer 21

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)

Question 22

what two agents are required when bonding metal indirect restorations with composite luting agents

Answer 22

dentine bonding agent - between tooth and luting agent
metal bonding agent - between luting agent and restoration

Question 23

what might be contained within temporary cements to weaken the structure of the set cement meaning easier removal

Answer 23

carnauba wax

petroleum jelly can also be added

Question 24

what are the two main types of temporary cement and what are the contraindications for one

Answer 24

either with or without eugenol
if forthcoming luting agent contains resin , eugenol free temporary cement should be used to prevent interference with setting

Question 25

self etching composite resin luting agents
- results in comparison to conventional composite agents
- price
- use of DBA

Answer 25

• poorer results compared to conventional composite resin luting agents
• expensive
• dentine bonding agent contained within the luting agent

Question 26

Dual cure composite luting cement
- brand example
- do i need DBA

Answer 26

Nexus universal
yes, DBA needed

Question 27

what is aquacem

Answer 27

GIC luting agent

Question 28

What is an example of a RMGIC for luting

Answer 28

RelyX luting