Clinical Assisting- Chapter 45

introduction:

• dental cements are a classification of dental materials that are routinely used in the placement of indirect restorations

indirect restorations: examples

• crowns, bridges

classifications of cements:

• type 1

• type 2

• types 3

classifications of cements: type 1

• luting agents

• include- permanent & temporary cements

classifications of cements: type 2

• restorative materials

• ex. glass ionomers

classifications of cements: type 3

• liners or bases placed w cavity prep

luting: meaning

• cementing

type 1 dental cements: act as

• adhesives to hold together the casting and the tooth structure

luting agents: designed to be

• either permanent or temporary

permanent cements:

• used in long-term cementation of restorations

• ex. inlays/onlays, bridges, veneers, & ortho fixed appliances

temporary cements:

• used if a restoration would have to be removed as a results of sensitivity or other symptoms

• also- temporary cementation of provisional coverage

temporary cements: should last

• 2 weeks

• also called provisional

variables: affecting cements

• mixing time

• humidity

• powder-to-liquid ratio

• temperature

variables affecting cements: mixing time

• follow manufacturers directions

• measure- powder & liquid according to use

• separate powder & liquid to make space for mixing

• divide powder into increments

• when size varied- smaller increments are incorporated 1st

• powder into liquid and mix thoroughly

variables affecting cements: humidity

• premature exposure to warm temp or humidity can result in a loss of water from the liquid or addition of moisture to the powder

• (shorter shelf life)

variables affecting cements: powder to liquid ratio

• incorporating too much or too little powder will alter the consistency

variables affecting cements: temperature

• some cements undergo an exothermic reaction

types of cements:

• glass ionomer

• composite resin

• zinc oxide eugenol

• polycarboxylate

• zinc phosphate

remember:

• composite resin cement- is not the same as composite

types of class ionomer:

• type 1

• type 2

• type 3

types of class ionomer: type 1

• for cementation of metal restorations and direct-bonded ortho brackets

types of class ionomer: type 2

• designed for restoring areas of erosion near gingiva

types of class ionomer: type 3

• used as liners & dentin-bonding agents

• ex. vitrabond

vitrabond:

• light cured

• click or

glass ionomer:

• most offices use

• releases fluoride

• use with anything

glass ionomer: benefits

• slow release of fluoride from powder- helps inhibit recurrent decay

• causes less trauma or shock to the pulp than do many other types of cements

• low solubility in the mouth

• adheres to slightly moist tooth surface

• very thin film thickness, excellent for seating ease

ZOE:

• irritates gums

• “dental smell”

glass ionomer: supply

• type 1- powder/liquid

• type 1- premeasured capsules

glass ionomer supply: powder/liquid

• mixed manually on a paper pad or cool, dry glass slab (increases working time)

glass ionomer supply: premeasured capsules

• triturated & expressed through a dispenser

composite resin: uses

• cementation of ceramic or resin inlays & onlays

• cementation of ceramic veneers

• cementation of ortho bands

• direct bonding of ortho brackets

composite resin: supply

• powder & liquid mix

• syringe-type applicator

• light-cure/dual cure system

composite resin supply: syringe type applicator

• base & catalyst

composite resin supply: light-cure/dual-cure system

• recommended portions of either application are dispensed onto paper pad and mixed rapidly w the use of a spatula

ZOE: chemical makeup

• liquid- eugenol, H2O, acetic acid, zinc acetate, calcium chloride

• powder- zinc oxide, magnesium oxide, silica

ZOE: types

• type 1- temporary cement

• type 2- permanent cement

ZOE: temporary cement (type 1)

• lacks strength and long-term durability and is used for temporary cementation of provisional coverage (IRM)

ZOE: permanent cement (type 2)

• has reinforcing agents added for the permanent cementation of cast restorations or appliances

ZOE: cannot

• be used under composites or glass ionomers as it will alter the setting time of these materials

ZOE: type 1 (picture)

• even lengths

ZOE: supply

• type 1- paste

• type 2- liquid/powder

ZOE supply: type 1 paste

• supplied as a 2 paste system as temporary cement

• pastes dispensed in equal lengths on a paper pad and mixed

ZOE supply: type 2 liquid/powder

• mixed on an oil-resistant paper pad

• mixing time of 30-60 secs

• setting time in the mouth of 3-5 minutes

ZOE liquid/powder: mixing time

• 30-60 seconds

ZOE liquid/powder: setting time

• in the mouth- 3-5 minutes

polycarboxylate: use

• permanent cement for cast restorations, stainless steel crowns, and ortho bands

• as nonirritating base under both composite & amalgam restoration

• intermediate restoration

polycarboxylate: supply

• powder/liquid

polycarboxylate supply: powder/liquid

• liquid may be measured w the use of either a plastic squeeze bottle or a calibrated syringe-type liquid dispenser

• liquid has a limited shelf life bc it thickens as its water evaporates

• mixing is carried out on a nonabsorbent paper pad

polycarboxylate: has a

• short shelf life

• don’t use in office much bc of that

zinc phosphate: types

• type 1- permanent cement (fine grain)

• type 2- base (medium grain)

zinc phosphate types: permanent cement (fine grain)

• used for permanent cementation of cast restorations

• provides- very thin layer necessary for accurate seating of castings

• ex- crowns, inlays, onlays, bridges

zinc phosphate types: base (medium grain)

• type is recommended for use as an insulating base for deep cavity prep

zinc phosphate: is very

• irritating to the tooth surface

• not commonly used

zinc phosphate: supply

• type 1- powder/liquid

zinc phosphate supply: powder/liquid

• powder is divided into increments of varying sizes

• powder added into liquid in small increments

• cement must be- spatulated slowly over a wide area of a cool, dry, thick glass slab to dissipate the heat

why we don’t use zinc phosphate:

• should sting up an inch

• perfect drop- bottle should be vertical

• use side of spatula

cement removal:

• operators preparedness & knowledge

• procedures requires

  • explorer, mouth mirror, spoon evacuator

• use fulcrum

• dental floss in and around the embrasure area

our duty:

• remove cement

most likely not going to see in offices:

zinc phosphate