page_title: Dental material
section_title: Type
hierarchical_section_title: Dental material / Lining materials / Type
caption_attribution_description: English: Calcium silicate liner as a pulp capping
context_page_description: Dental products are specially fabricated materials, designed for use in dentistry. There are many different types of dental products, and their characteristics vary according to their intended purpose.
context_section_description: Calcium Hydroxide
  Calcium Hydroxide has a relatively low compressive strength and a viscous consistency making them difficult to apply to cavities in thick sections, a common technique used to overcome this issue would be to apply a thin sub-lining of a calcium hydroxide lining and then building up with zinc phosphate prior to amalgam condensation.Generates a relatively high pH environment around area surrounding the cement due to calcium hydroxide leaking out thus making it bactericidal. It also has a unique effect of initiating calcification and stimulating the formation of secondary dentine due to an irritation effect of the pulp tissues by the cement. It is also radio-opaque and acts as a good thermal and electrical insulation. However, due to its low compressive strength it is unable to withstand amalgam packing thus a strong cement base material should be placed above it to counter this. Calcium silicate-based liners have become alternatives to calcium hydroxide and a preferred material among practitioners for its bioactive and sealing properties; the material triggers a biological response and results in formation of bonding with the tissue. Commonly used as pulp capping agents and lining materials for silicate and resin-based filling materials.
  It is usually supplied as 2 pastes, a glycol salicylate and another paste containing Zinc Oxide with Calcium Hydroxide. On mixing a chelate compounds are formed. Light activated versions are also available which contains polymersiation activators, hydroexyethyl methacrylate, dimethacrylate which when light activated will result in a light activated polymerization reaction of a modified methacrylate monomer.
  Polycarboxylate cement
  Polycarboxylate cement have decent compressive strength to resists amalgam condensation and are acidic but less acidic then phosphate cements due to it having a higher molecular weight and polyacrylic acid being a weaker acid than phosphoric acid.They also form a strong bond with dentine and enamel allowing it to form a coronal seal. In addition it is an electrical and thermal insulator while also releasing fluoride rendering it bacteriostatic, furthermore it being radio-opaque makes it an excellent lining material.
  Care has to be taken in handling such material as it has a strong bond with stainless steel instruments once it sets.
  Commonly used as luting agents or as cavity base materials, however they tend to be rubbery during its setting reaction and adhere to stainless steel instruments thus most operators would prefer not to use them in deep cavities.
  It is usually supplied as a power containing Zinc Oxide and a liquid containing aqueous Polyacrylic acid. The reaction consists of an acid base reaction with Zinc oxide reacting with the acid groups in polyacid to form a reaction product of unreacted zinc oxide cores bound by a salt matrix with polyacrylic acid chains cross linking with zinc ions.
  Glass ionomer
  It has the strongest compressive and tensile strength out of all the linings, thus it can withstand amalgam condensation in high stress bearing areas such as class II cavities. GI is used as a lining material as it is very compatible with most restorative materials, insulates thermally and electrically and adheres to enamel and dentine. Lining GI contains glass of smaller particle sizes in comparison to its adhesive restorative mix to allow formation of a thinner film. Some variations are also radiopaque which makes it good for X ray cavity detection. In addition, GI is bacteriostatic due to its fluoride release from un-reacted glass cores.
  GIs are usually used as a lining material for composite resins or as luting agents for orthodontic bands.
  The reaction is an acid-base reaction between silicate glass powder and polyacrylic acid.  They come in a powder and liquid which are mixed on a pad or in compules which are for single usage and light cured with a LED light curing unit. Setting takes place by a combination of both an acid based reaction and chemically activated polymerization, light cured versions contain a photo-initiator usually 
caption: Calcium-silicate liner used as a pulp capping material
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