DM Sheet #13 By Reham Kilano

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DM Sheet #13 By Reham Kilano

Post by Sura on 27/12/2011, 10:27 pm

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Re: DM Sheet #13 By Reham Kilano

Post by Shadi Jarrar on 2/1/2012, 11:09 pm

Biological considerations in Dental materials:

People whom should be taken into considerations in the biological effects of DMs are the Dentist,patient,Nurse and the technician

Patient-wise:

Allergens :

-Euogenol

-colofonia which is a solid form of resin obtained from pines and some other plants

-polyether impression materials

-gold palladium restorative materials Inlays and onlays and in these patients we should obviously turn into another material which is usually the zirconia

-Methacrylates can cause thermal production

The last two materials mainly causes Contact dermatitis

-disinfectants

-anesthetics

-Nickel contetnts: Usually people with nickel allergy have palladium allergy as well.

Nickel allergies are most common among females and so dentists should take care and inform the technician to prepare the crown,for example, nickel free. Nickel free materials are usually Co/Cr

** Titanium mateerials are more biocompatible so they are an alternative in case of mickel allergies but a major drawback is their expensive cost

-Formaldehydes this is mainly used in REDOS of endodontic treatments as it makes the gutta percha more flexible thus easier to remove

-Mercury vapor

Now to confirm that someone is allergic to one of these materials we have what is called a Patch test which-in summery-is a test used to help identify which substances may be causing a reaction in a patient. It is intended to produce a local allergic reaction on a small area of your back where the diluted chemicals were planted. The chemicals included in the patch test kit are the offenders in approximately 85-90 percent of contact allergic eczema(Contact dermatitis) and include chemicals present in metals

Local toxic reactions: most of our DMs can cause this in one way or another and a common example of those is the Latex gloves which have corn powder in their contents

Systemic toxic reactions and our greatest fear is the carcinogens and these include :Formaldehyde, cadmium and beryllium ,these two are mainly found in metals so technicians are most liable to get them! Many Publications on their carcinogenic effects have been reported



Denture base polymers can have a water absorption ability and microorganisms can colonize it, another importants thing is the monomer concentrations, High monomer content cause irriation and Burning to the tissues that’s why its advisable to tell your patient to soak the denture in water which helps in extruding the monomers out of the denture ..High monomer levels cause denture stomatitis in all patients whether they were allergic to it or not..And so the highest limit of it is 2.2%

-Reline materials can also cause allergy in the same way as the monomers work



Jumping to Dental Amalgam :

-Amalgam is not used in Scandinavian countries and some of the European countries and Japan these countries have done many surveys one preterm delivery and abortion with how many amalgam fillings they have got!



Resin based fillings like composite:

-Generally they are biocompatible but some researchers have said that it could be irritant before curing

-Composite containing crystalline silica have been found to be carcinogenic

-Toxicity is measured by putting some kind of cells in a test tube and a fixed conc. Of the material to be tested and they measure the rate of growth of cells while they are with the material and this give a relative indication of toxicity

-cytotoxicity essay is a way of measuring toxicity by measuring an enzyme called succinate dehydrogenate,which measures the cytotoxic effect of a certain material

-remaining cell number is also a way of measuring cytotoxicity

Cements:

Mechanically zinc phosphate is stronger than polycarboxylate: when they measure the ability to break from a prepared tooth structure they see which is more resistant to pulling forces

-Zinc phosphate is not used on vital teeth due to its pulpal irritation as a result of its low PH( 2-4),while we can use polycarboxylate because it a weaker acid thus has a higher PH also, it has a longer type of chains which makes its passage into the dentinal tubules way less than that of zinc phosphate

-GI cements work in the same way as that of polycarboxylate



That’s all For Today

Goodluck J

Reham kilano

DM lec. For Dr. Ameen Khresiat
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Shadi Jarrar
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