Dental Cements - Professor Sherry Frey PDF

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Professor Sherry Frey ...

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Dental Cements Luting Agent - gluing, sticking, cementing, adhering - inlays, crowns and bridges, other restorations - oozes out in the presence of saliva - scale it off Pulp Protection - used as intermediate bases or liners when remaining dentin is to be less than 2mm thick - a base or liner is placed on the dentin between pulp and restorative materiel - direct pulp cap is direct contact or hit of the pulp - indirect pulp cap is super close but no hit to the pulp - sometimes when theres a direct hit, the client is sent to the endodontist for a root canal - a ZOE can be put in for $25 (dentin will form, seen on radiographs) Bases - solid and thicker (STRONG) - fill the holes to protect from thermal changes (provides insulation) - pulp doesn't like cold or hot, likes body temp - some bases support, some release fluoride, and some irritate pulp before it sets - such bases are used in conjunction with a liner Liners - protect the pulp from chemical irritants - calcium hydroxide (liner) may stimulate secondary dentin or release fluoride - liners are too thin (0.5mm) to provide thermal insulation and are too weak

1.Carious lesions present 2.Tooth is prepared 3.Temporary filling is placed 4.Temporary filling cut, leaving cement base 5.Base covered with permanent restoration 6.Liner is much thinner than a base

Temporary Restorations - temporary restorative materials are heavy putty - could be temp fillings placed in an emergency - seniors in nursing homes benefit the most from these - kids living up north also benefit from it (no care, accesses) - done with time constraints, pulpal pain, and other symptoms such as irreversible pulpits

- calcium hydroxide is a thin layer that is applied when the pulp is hit - is the only product that is good at talking to cells - the periphery (outer part) of the pulp is made of odontoblast cells

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tells them to do something, makes more dentin and lays down a hard hat (cap) of dentin ZOE, BNT, or IRM is used to fill the space on top of the calcium hydroxide (lets it heal, protects) a whole temporary is to the top, a base is just filled a portion ZOE is an obtudent sedative (calms the tooth down) IRM is stronger

Powders Used in Dental Cements - powders are ground and sieved to get the right particle size - size of particles determines film thickness of resulting mixed cements - too large of particles results in high thickness, open margins, and recurrent decay - reactivity is controlled by manufacturer and is matched to reactivity of liquid component Zinc Oxide - only insoluble, nontoxic, reactive oxide or hydroxide available to react with an acid - common additives are aluminium oxide (alumina), which is strong, inert, and forces resulting cement - oxides such as magnesium control setting rate - zinc oxide has some antibacterial effects, and is in diaper rash powder, sunscreen, and foot powders Powdered Glass - silicon oxide (chemical formula) is unreactive - if oxides of sodium, calcium, and potassium are added, glass with react with a strong acid - powder is white became its made of small, translucent, glass particles - formulation also contains fluoride (additive because it reduces melting temp and improves flow) - fluoride in glass powder gives cement the ability to release fluoride and inhibit recurring cavities Liquids Used in Dental Cements Eugenol - organic liquid that is a weak acid (major component oil of cloves, so it smells and tastes like cloves) - phenol derivative, antibacterial, obtundent to pulp (reduces irritation) - inhibits free radical polymerization, which limits eugenol containing cements - this inhibits set of composite restorative materials - other organic liquids can be added to eugenol to make cements (most notable is ethoxybenzoic acid) - does not mix with plastic, composites - NO WATER WITH ZOE MIX Phosphoric Acid - about 2/3 phosphoric acid and 1/3 water (acidic and irritating to issues in and out of the mouth) - water present affects reactivity of liquid by changing ionization of phosphoric acid - keep the cap on the bottle and don't use liquid until you're ready to mix cement - high and low humidity affect water content (also pH, reactivity, and resulting cement properties) - if its cloudy, its outdated and should be thrown out Polyacrylic Acid - lots of cements use an aqueous solutions of this that are 30-50% acid by weight (viscous) - polyacrylic acid can bond to calcium in tooth structure - be careful when dispensing, viscous liquid may not form independent drops (run together) - this results in variations and inaccurate amounts of liquid - don't dispense until ready to mix (water can evaporate and change reactivity and cement properties) - shouldn't be stored in the fridge (gel and become unusable) - carboxyl groups bond to calcium in teeth (stable bond in wet environment) - water hardening or water setting cements use anhydrous or freeze dried acid

- zinc oxide or glass powder mixed with anhydrous form - combined powder mixed with mostly H20 (acid dissolves in H20 and reacts with zinc oxide or glass) Components and Resulting Cements Components

A. Zinc Oxide Powder

B. Glass Powder

1. Eugenol

ZOE Cement

No Reaction

2. Phosphoric Acid

Zinc Phosphate Cement

Silicate Cement

3. Polyacrylic Acid

Polycarboxylate Cement

Glass Isomer Cement

Reference Guide for Liners, Bases, Cements Cement

Use

Mixing Technique

Mixing Time

Proper Mix

Setting Time (min)

Calcium Hydroxide

Cavity Liner

mix quick in small area of paper pad

10s

uniform color

2-3 min

Zinc Phosphate

Luting Agent

add divided increments in specified time using big slab area

1-1.5 min

mix stretches 1” between slab and spatula

5.5 min

Base

same as above

1-1.5 min

thick, putty like (no stick) consistency

5.5 min

Luting Agent

add powder to liquid in 1 portion

30-45s

use while glossy

7 min

paste/paste; mix equal amounts

20-30s

uniform color

5 min

Base

same as above

30-45s

use while glossy

7 min

ZOE

Base and Temp Restoration

add 1/2 scoop increments using small mixing area

1.5 min

thick, putty like (crumbly) consistency

2.5-3.5 min

Polycarboxylate

Luting Agent and Intermediate Base

add powder to liquid in 1 portion

30s

use while glossy

10 min

Temporary

Temp Luting Agent

equal lengths; mix all at once

30s

uniform color

5 min

Composite

Luting Agent

mix equal amount of pastes

30-45s

uniform color

5 min

Glass Ionomer

- do not mix powders and liquids of different cements or different products of the same type

1. Temporary Restorative Materiels - placed in an emergency when time prevents a more complex treatment - also used for pulpal pain (such as irreversible pulpits) 2. Temporary Materials as a Base - when temporary fillings are placed, part of the temporary filling is removed (ex. 3 months) - radiographs are taken of the are to see if dentin was formed by calcium hydroxide - remaining temporary materiel then becomes a base, which is then covered with a permanent restoration Caries Control - 2 used frequently used for caries control are ZOE and glass ionomer cement - light cured glass ionomer materials will bond to composite materials to a certain extent - light cure glass ionomers may be used for cares control Varnish - composed of resins dissolved in a solvent - like painting on clear nail polish (resin stays behind) - not thick enough to affect thermal sensitivity - NEVER TO BE USED WITH COMPOSITE MATERIALS - it interferes with adhesions and breaks it down - some dentists are substituting dentinal bonding agents for varnish Components Dictate Handling and Mixing - for ZOE and Zinc Phosphate - base or temporary mix is thicker than luting mix - higher powder/liquid ratio= more strength, viscosity, lower solubility, working time, and better cement - if a luting mix gets too thick, restoration may not seal tight, marginal gaps increase, greater caries risk - micro mechanical retention is reduced - glass ionomer and polycarboxlyate cements have powder liquid ratios determined by manufacture - follow the directions - mixed cement must be fluid enough to wet the tooth for micro mechanical and chemical adhesion - acid groups react with powder and are available to react with tooth structure - chemical adhesion is then reduced or even eliminated - paper pads are used to mix many cements - cements may weaken the pad - a thick glass slab is favoured to mix zinc phosphate cement - typically slab is cooled to improve resulting mix

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orange solvent and soap and water to clean up water accelerates ZOE setting reaction ZOE sets faster in the mouth ZOE is old but useful obtudent property makes it useful for sedative and temp fillings

Zinc Phosphate Cement - zinc phosphate cement powder (Flex, Hybond) mixed with phosphoric acid - dispensed on a chilled glass slab - powder divided into increments - use the entire surface of the glass slab (failure to do so results in a fail) - must “stretch” 1 inch above slab - strong, low solubility, low pH (acidic until sets), very irritating to pulp - never used as a base, liner, or putty

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sets to a hard brittle materiel, withstands forces when mixed, cement is proper consistency (only use for luting) setting reaction is very exothermic (heat accelerates setting rate) mix over large area on a chilled glass slab to dissipate heat for 10-15s nearly insoluble in water (quick clean up) good for luting inlays, crowns, bridges, ortho bands…

Glass Ionomer Cements - formed when glass powder mixed with aqueous solutions of polyacrylic acid - strongest and least soluble dental luting cement (with exception of composite cements) - adhesive, release fluoride, good biocompatibility, bond to tooth structure - bond to stainless steel and alloys for ceramometal crowns - popular because of physical and mechanical properties - first ones that came out set by acid based reactions - we now use resin modified or reinforced that set via acid base and addition polymerization - acid base is mixing powder and liquid, and polymerization is using injection molds - one of the most popular luting materials - come in acid base and resin reinforced products - Resin modified glass ionize cement is the material of choice for all metal ceramometal crowns - glass ionomer products are stronger and tougher - direct polymeric restorative materials set the same way as luting products, but they're thick and strong - acid base liner materials, but there are more light activated resin reinforced glass ionomer liners - glass ionomer restorative cam be used for restorative (IST) - mixed quickly, don't exceed working time (20-30s or less) - restorations should be seated in less than 2 mins - cam come in pre measured capsules, powder and liquid, and paste dispensers - capsules mixed in an amalgamator with a dispenser (popular but expensive) - paste dispensers come out as one homogenous colour - powder diseased with scoop, liquid as drops using a cement spatula (precise ratio) using paper pads - cement should appear glossy (dull is set) - clean up fast Polycarboxylate Cement - zinc oxide powder mixed with aqueous solution of polyacrylic acid - first adhesive material developed - polycarboxylate cement bonds to tooth surfaces with very little leakage - biocompatible, used as a luting cement, intermediate base, not very strong, moderate solubility - can release fluoride, but glass ionomer is stronger and better (ionomer is more popular) - powder and liquid mixed on paper pad with metal spatula - mixing time 20-30s, placed inside crown and seated while its still glossy - comes with a stick (plunger) to pack it...