Cements

Cement has many definitions but can be considered as a binder -A substance which sets and hardens independently, and can bind other materials together

-Number of direct restorative materials are placed in dentine that are in close proximity to the pulp • Immediate restorative materials (cavity varnishes/liners/bases) • Luting- fitting crowns • Temporary restorations • Endodontics

Temporary restorative material

• Barrier between filling material and dentine • Provides a thermal, chemical and electrical barrier • Protects the pulp from bacterial invasion • Pulp may be damaged and may die • Effects of bacteria and their metabolic products • Due to effects of microleakage post restoration • Thermal insulation • Chemical barrier: prevents diffusion of irritable chemicals, for example monomer leakage • Electrical barrier: protection from galvanic pain

2 paste cements: -One paste contains 50% calcium hydroxide, 10% zinc oxide and 40% ethyl toulene sulphonamide • Other paste contains 40% butylene glycol disalicylate, titanium dioxide and calcium sulphate • Setting reaction is one of chelation between the ZnO and butylene glycol disalicylate (initial hardening) • Freshly mixed cement has a high pH (12) and is thought to enhance the formation of secondary (tertiary??) dentine

• Very brittle • No mechanical integrity • Dissolve easily • Compressive strength is low • Mainly used as a sub-liner/pulp cap under zinc phosphate • Calcium hydroxide: for direct pulp capping when a pulp exposure is suspected

• MTA has been suggested for use as a pulp capping material • MTA mixed with water hydrates to form calcium silicate hydrate and calcium hydroxide • Needs moisture to set • Made up of fine hydrophilic particles that set in the presence of water, forming a solid cement -Composed of tricalcium silicate, dicalcium silicate, tricalcium aluminate, tetracalcium aluminoferrite, calcium sulphate dihydrate and bismuth oxide (radioopacifier)

• Grey and white - Only difference is the presence of iron in grey MTA

Root-end filling material Subsequently been used for pulp capping, pulpotomy, apexogenesis, apical barrier formation in teeth with root apices, repair of root performations -Seals off the pathways of communication between the RC system and surrounding tissue, significantly reducing bacterial migration

• Calcium-silicate based cement • Can be used in pulp capping, root perforations and dentine replacement Powder: • Tricalcium silicate • Dicalcium silicate • Calcium carbonate • Oxide filler • Iron oxide shade • Zirconium oxide Liquid: • Calcium chloride as an accelerator • Water soluble polymer that serves as a water reducing agent

• Setting time must shorter than tradiitonal MTAs (9-12mins) • Increase in particle size, addition of calcium chloride to the liquid component results in a shorter setting time • Has the ability to release calcium when in solution and is a source of hydroxyapatite in contact with synthetic tissue fluids • Biodentine is designed to treat damaged dentine both for restorative and endodontic indications • Can be veneered with composite

-Used when cementing a crown • Easy of manipulation • Low film thickness (high thicknesses result in increased chance of cohesive failure) • Long working time with rapid setting at mouth temperature • Low solubility in oral fluids • Adhesion to tooth structure and restorative material • Adequate tensile and compressive stregnth • Biocompatible • Anticarogenic properties

• Zinc phosphate • Zinc oxide eugenol • Zinc polycarboxylate • Resins • GICs

pH is around 2 of a freshly mixed cement • Rises to 5.9 with 24 hoyrs and is nearly neutral after 48 hours • Setting rxn is exothermic and this limits the mixing time • Mixing time is 5 mins, setting time is 15 mins Variables • High powder:liquid ratio accelerates the rxn • Moisture accelerates the rxn • Low temperature retards the rnx thus mixing can be done on a cool slab but not below the dew point • Rapid addition of powder accelerates the rxn • Limited value as a lining cement • No therapeutic effect on pulp • Type II used as a luting cement but may cause post insertion sensiticity

Composition on slides • Formation of zinc polyacrylate • Physical properties are comparable to zinc phosphate and the setting exotherm is lower and initial pH is higher • Adhesive to the tooth structure

• Temporary use only • pH is relatively neutral • Natural bacterucude • Mild pulp irritant • Eugenol can act as a free radical sink and should not be used with composites as it inhibits polymerisation • Can also cause discolouration of the composite

-Lower solubility and higher strength than conventional ZoE

• Good retention • Fast setting • Easy to clean up • Low sensitivity • Ease to remove

• Remove the pulp and all its remnants • Canal and pulp chamber are cleaned and sealed • Sealed to prevent infection to adjacent bone • Permanent restoration intended to obturate pulp space of the tooth

• Ability to seal completely • Retain seal over extended periods (indefinite) • Bactericidal • Good compatibility with bone/tooth interface • Appropriate mechanical strength

Rigid root fillings • Metallic • Polymeric Plastic root filling • Zn-O-eugenol • Epoxy resins • GIC • Calcium hydroxide

• Semi-plastic, structural isomer of natural rubber • Trans-poly (1,4 isoprene) • Properties diffuer from natural rubber (cis isomer) • Harder, lacks resilience and cannot be stretched reversibly -Polymeric cones of gutta percha with other constituents such as ZnO, barium sulphate, plasticisers and pigments

+: • Semi plastic nature allows reshaping and remoulding • Biocompatible at the root tip • Radioopaque • Can be removed and replaced if required • : • Lack of rigidity makes the placement difficult • Root canal preparation is critical • Must be confined to prevent excess material being expressed beyond the apex • Ages rapidly, becomes brittle

• Via orthograde approach (ie from the crown of the tooth) • Retrograde approach (directly into the apex via a surgical approach) • Well tolerated by tissues • Build up of amalgam in the oral mucosa results in so called amalgam tattoos +: • Inexpensive • Radiopaque • Long shelf life • Plastic on insertion with a quick setting time • : • Difficult to condense into the root canal • Tends to be expressed beyond the apex of the tooth • Usually shows considerable leakage