Heavy Metal Toxicity

Question 1

Biocompatibility

Answer 1

the ability of a material to perform with an appropriate host response in a specific application

Question 2

Properties of a biomaterial (biocompatible material)

Answer 2

• does not elicit adverse effects when implanted into the body
• does not interact negatively with or irritate oral or dental tissue
• should not contain diffusible substances that can cause systemic toxic responses
• should not provoke an inflammatory response
• should not contain potentially sensitizing agents
• should have no carcinogenic potential

Question 3

Irritation

Answer 3

Local redness, bulla, or ulcers right after contact with an irritant
- No antigen-antibody response

Question 4

Allergy

Answer 4

Small amount of an allergen (from a material) causes antibody production

Question 5

Toxicity

Answer 5

Causes cell necrosis

Question 6

Carcinogenicity

Answer 6

Low-level sub-toxic concentrations

Long periods of incubation may occur before symptoms are recognized

Question 7

Heavy metals

Answer 7

Specific gravity higher than 4.0

Question 8

Examples of metals with dental implications

Answer 8

Be, Ni, Co, Cr, Pd, Au, Cu, Pt, Hg

Question 9

Bioelements

Answer 9

Elements that can exist in healthy normal functioning tissue

Question 10

What are the effects when bioelements are in shortage and subseq effects when they are recovered?

Answer 10

• When in shortage, a disorder occurs
• When added the disorder is recovered
• Disorder is accompanied by additional biochemical changes

-When recovered, the biochemical changes recover

Question 11

Abundance ratio is aka

- define

Answer 11

Concentration factor
- a ratio of concentration of an element between two phases
ie how much of these different elements are actually present in an organism

Question 12

What do u understand by indispensability of heavy metals?

Answer 12

• Essential elements must be present in adequate concentrations for growth
• Essential and non-essential elements have upper limits, above which growth is inhibited

Question 13

Significance of essential elements

Answer 13

Electrochemical function	
  - Free energy for ion transfer
Catalytic function
  - w/metalloenzymes such as Fe, Cu, Zn, Mo
Structure
  - Ca and P form hydroxyapatite
Metalloprotein
  - E.g. Hemoprotein

Question 14

Mechanisms of metal absorption into our bodies

Answer 14

- 3 primary routes:
        Digestive system
        Skin
        Respiratory tract
- Transfer mechanisms
        Passive transport
               Concentration dependent
        Active transport
               “Required level” dependent ie active transp. brings in a req’d amt that’s needed for approp f(x)

Question 15

Excretion pathways

Answer 15

Feces
       unabsorbed
Urine
Skin
       sweat, hair, nails
Digestive system
        Liver-gallbladder-bile-digestive system
        Pancreas-pancreatic juice-digestive syst.

Question 16

Degree of toxic severity by route

Answer 16

I.V > Inhalation > subQ > Oral

Question 17

True or False: Organic cpds pass memmbranes and barriers easier than inorganics.

Answer 17

True

Question 18

How would you get Hg in vapor form?

Answer 18

High speed handpiece - aerosol vaporizes it coz of heat being generated btwn the bur and restoration

Question 19

Statement 1: Bioelements or essential elements exhibit a homeostasis where body concentrations are maintained by daily intake
Statement 2: Toxic elements tend to be maintained within the body for long periods of time and Homeostasis is not maintained. Which of these statements is true/false?

Answer 19

Both statements are true.

NB: To get rid of the foll from the body
Pb = 250days
Inorg Hg = 70 days
Org Hg = 120 days

Question 20

Treatment of intoxication

Answer 20

By chelation: Promotion of excretion by masking the heavy metal or converting it to a non-poisonous state inside the body

By symptomatic therapy in accordance with the clinical situation

Question 21

The most common chelator used… why?

Answer 21

British Anti-Lewisite (BAL)

- it has a broad application: chelates multiple elements without impacting iron (goal is not to get pple anemic from it)

Question 22

Corrosion

Answer 22

Oxidation-reduction responsible for release of cations from metallic dental materials

Question 23

Metal ion release from alloys is not generally proportional to nominal alloy composition AND The release of metal ions cannot be predicted from the nobility or the overall composition of a casting alloy.
Which of the 2 statements is true/false?

Answer 23

Both statements are true

Question 24

The ADA and ISO will no longer provide specification certifications for which materials? And why?

Answer 24

Berryllium-containing alloys
-Inhalation of beryllium (Be) has been associated with 2 pulmonary syndromes; an acute chemical pneumonitis and a granulomatous lung disease known as chronic beryllium disease (CBD), or berylliosis.