Lecture 11: Cements Flashcards
what do dental cements do?
create a connective layer to adhere to the two surfaces
what are the classifications of dental cements?
- type I: luting agents, permanent and temporary
- type II: restorative materials (fillings)
- type III: liners (pulp capping) or bases (protection) placed within cavity
when are permanent cements used?
long term cementation of inlays, crowns, bridges, laminate veneers, orthodontic fixed appliances
what are temporary cements used for?
provisional coverage to protect the tooth until the permanent restoration is ready to be cemented
what are resin-based cements?
low viscosity versions of restorative composites
what is a one paste system and a two paste system for resin-based cements? and how are they cured?
- one base: methylacrylate monomers, initator
- two base:
*base paste; methylacrylate monomers, initiator
*catalyst paste: methylacrylate monomers, initiator, activator - curing: light (less common) or chemical reactions
what are temporary resin cements used for ?
- eliminate the problem of potential contamination of teeth by eugenol and other oil based cements when bonding agents and resin cements
temporary resin cements have _______, meaning they are easy to remove
low bond strength
the commercial example of a resin based cement, 3M - ESPE RelyX Veneer cement, has what composition?
resin: BISGMA and TEGDMA
fillers: zirconia/silica and fumed silica
bases are generally _____ than cements and provide ______ for the pulp
stronger, thermal protection
low strength bases function as what?
barrier to irritating chemicals
also called liners
glass ionomer cements (GIC) are what type?
water based
what can glass ionomer cements be used for?
- as restorative: class III and V, intermediate restorations
- as luting: luting cements, adhesives for orthodontics
- as base: pit and fissure sealants, core build up materials
what is the composition of glass ionomer cements and what is the reaction?
- liquid: polymeric-water soluble acid
- powder: glasses
- water
- reaction: formation of a cross linked gel matrix that surrounds the partially reacted powder particles
what happens during the setting reaction of glass ionomer cements?
- acids starts to dissolve the glass (powder) releasing calcium, aluminum, sodium and fluorine ions
- polyacrylic acid chains are then cross linked by Ca2+
- fluorine ions are dispersed in the matrix
what does the addition of tartaric acid do to GICs?
decreases viscosity, increases work time and shortens setting time
what is the glass (powder) composition?
silica, calcium, alumina and fluoride
what do fillers control in the glass (powder) composition?
- the release of ions
- the setting characteristics
- solubility
- release of fluoride
glass ionomers chemically can bond to tooth structure by ?
chelation of the carboxyl groups of the polycarboxylate acids
glass ionomer cements have relatively _____ mechanical response and the retention of them is primarily _____ but some _____ occurs
low, micromechanical, chemical bonding
GIC are considered superior to many types of cements because ?
they are adherent and translucent
what do GICs release for an anti-carcinogenic effect?
fluoride which inhibits demineralization
resin modified glass ionomer cements are what????
water based
what are resin modified glass ionomer cements used for?
water soluble methacrylate-based monomer that used to replace part of the liquid component of conventional GIC
what is the composition and reaction of RMGIs?
-powder: fluoroaluminosilicate glass and a microencapsulated catalyst system
- liquid: polycarboxylic acid modified with methacrylate, HEMA, tartaric acid
curing: acid-base glass ionomer reaction using chemicals, lights or both
zinc oxide eugenol is ?
oil based
what are some characteristics of zinc oxide eugenol?
- sedative effects on the pulp
- cementation on prepared teeth with dental tubules
- commonly used for luting and intermediate restorations
- short term cementation
- weak and easily cleaned from casting
what is the composition and reaction of type I zinc oxide cement?
powder: oxide, rosin and zinc acetate (accelerator)
liquid: eugenol
reaction: catalyzed by water, forms an amorphous chelate of zinc eugenolate
what is the composition of type II zinc oxide cement (polymer reinforced)?
- powder: zinc oxide and acrylic resin
- liquid: eugenol
what is the composition of type II zinc oxide cement (EBA reinforced)?
- powder: zinc oxide and alumina
- liquid: eugenol
**forms a stronger crystalline matrix
what are the cements used at KSoD?
-adhesive resin cement
- RMGI
- ZOE
- Resin-based
- luting