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Biocompatibility of Dental Materials Cheat Sheet by

Definitions and Tests

Defi­nit­ion:

Ability of a material to elicit an approp­riate biological response in a given applic­ation in the body.
Placement of a material creates an interface that is not normally present.
Interface = Not static, includes dynamic intera­ctions
Activity of interface depends on: location of material, duration in body, properties of material and health of host.

Key concepts of Biocom­pat­ibi­lty:

Biomat­erials are not biolog­ically inhert:
There are no inhert materials. Intera­ctions depend on the material, the host and forces­/co­ndi­tions placed on the material. Material affects the host and host affects the material.
Dynamic Process:
Body may change due to aging/­dis­ease. Material may change due to corros­ion­/fa­tigue. Changes may alter conditions where initially an approp­ria­te/­desired biological response took place. Biological response to a material is an ongoing process.

Property of a Material and Its Enviro­nme­nt:

Intera­ction

Orga­nis­ations That Test Dental Materi­als:

> Food and Drug Admini­str­ation (FDA)
> American National Standards Institute
> American Dental Associ­ation (ADA)
> Intern­ational Organi­zation for Standa­rdation
 

Meas­uring Biocom­pat­ibility of Materi­als:

Location:
Important to it's overall biological response. Determines if material will be covered by soft or minera­lized tissue, will it be external to oral epithelium or if it will commun­icate through epithelium and will the material be directly exposed to bone, tissues , blood and saliva or will there be a barrier (such as enamel or dentin).
Duration:
More stringent tests for longer duration.
Stress:
Stresses placed on material (physical, chemical, thermal or occlusal or reaction to salivary proteins) may react unfavo­urably.

In-vitro Testing:

Performed outside an organism
First screening test done in test tubes, cell culture dish, flask.
Material is placed in direct­/in­direct contact with some biological organism.
Advant­ages:
> Fast
> Inexpe­nsive
> Easily standa­rdised
> larger scale screening conditions can be tightly controlled to provide the highest quality of scientific rigor.
Disadv­ant­ages:
> Potential lack of relevance to the in vivo use of material.
> Lacks the complex co-ord­ination of systems (immune system, inflam­matory system, circul­atory system)

Animal Testing:

Place a material into contact with an intact organism
Distinct differ­ence, exposure without regard to the material’s final use
Advantage:Ability to allow an intact biological system to respond to a material.
Disadv­ant­ages:
> interfere with the many complex biological systems
> expensive
> difficult to control
> ethical consid­era­tions
> questi­onable
 

Usag­e/I­nvitro Testing:

Material is placed in an enviro­nment, clinically relevant to the use of the material in clinical practice
Humans ( clinical trial ) and Animals closely resembling humans
Advantage: Gold standard
Disadv­antage:
> Expensive
> Approval
> Legal liabil­ities
> Time consuming

Adverse Affects from Dental Materi­als:

1. Toxicity:
normally the first screening test.
2. Inflam­mation:
second fundam­ental type of biological response resulting either from allergy/ toxicity, first infilt­ration of neutro­phils, then monocytes and other lympho­cytes.
3. Allergic Reaction:
the most common to lay people. Type I- refers to an immediate atopic /anaph­ylatic reaction when an antigen reacts with mast cell/b­aso­phils. Type II- is a cytotoxic hypers­ens­itivity reaction. Type III-immun­e-c­omplex hypers­ens­itivity reaction. Type IV -delayed or cell-m­ediated hypers­ens­iti­vity. Type V - stimul­ati­ng-­ant­ibody reaction. Type VI- anti- body dependent, cell mediated cytoxicity reaction.
4. Mutage­nicity:
results when the components of a material alter the base-pair sequences of DNA in cells.

Local and Systemic Effects:

Local: Pulp of the tooth, period­ontium, root apex, soft tissues ( buccal mucosa­/to­ngue)
Systemic: Ingestion, absorption in the gut, , inhaled vapor, release a the tooth apex, absorption through the o/mucosa. As well as, Systemic biological response depends on; duration and concen­tration of the exposure, excretion rate of the substance, site of exposure.
 

Prin­ciples of Adverse Effects:

Degrad­ation process: The biological response to the corrosion products depends on the amount, compos­ition, and form of these products as well as their location in the tissues.
Surface charac­ter­istics: research has shown that for all dental materials , the surface is very different compared to the interior.
Examples:
Latex:(3 catego­ries: irritant, allergic & type1 hypers­ens­itivity reaction) In dentistry; rubber dam, gloves, bite blocks etc. Reactions to latex ; localized rashes, swelling to a more serious wheezing and anaphy­laxis. Dermatitis of the hands (most common).
Mercur­y&­Ama­lgam: No data to show that mercury released from dental amalgam is harmful.
Estrog­eni­city: Ability of a chemical to act as the hormone estrogen in the body The placement of composites has been questi­oned. Xenoes­trogen bisphenol A ( BPA) synthetic starting point for all Bis-GMA composites fear is that the release of these substances might alter normal cellular develo­pment or mainte­nance if the BPA has estrogenic effects.
NIckel: Common component of many dental alloys including those used for crowns, fixed partial dentures, removable partial dentures and some orthod­ontic applia­nces. Endodontic files Reactions are often subtle, resemble period­ontal inflam­mation Occurs primarily outside the mouth
Beryllium:
if inhaled cause chronic inflam­matory condition- beryll­iosis, the lung is engorged with lympho­cytes and macrop­hages. T cells in suscep­tible indivi­duals prolif­erate locally in the lung tissue ,in delayed hypers­ens­itivity reaction too the beryllium metal. Occurs in indivi­duals with a hypers­ens­itivity to beryllium and may occur from inhalation of beryllium dusts, salts, fumes as those encoun­tered when casting beryll­ium­-co­nta­ining alloys.

Adverse Effects of Restor­ative Materi­al:

 

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