4/1: Dental Materials - Biocompatibility Flashcards
How is biocompatibility associated with the environment?
Works both ways - material may affect the environment and/or the environment may affect the material
The material must be of benefit to the patient and above all, the patient must be _____________________________
Safe from any adverse reactions
What level can biological reactions take place?
Either at a local level (injection site) OR far removed from the site of contact (systemically adverse Rx from acrylic monomer in a denture (denture stomatitis)
What are other ways that there can be a reaction?
Systemically may not always be readily apparent - dermatological, immune-mediated, neural reactions
What is the most common reaction to dental staff?
Hand/facial dermatitis or respiratory symptoms
What are possible interactions between restorative material and the biological environment?
- Post operative sensitivity
- Toxicity
- Corrosion
- Hypersensitivity/allergy
What is the toxicity of dental materials?
Nanomaterials (size of 1-00nm) growing concern about their biosecurity and crossing the blood brain barrier and going to the central nervous system
What can amalgam or its components cause?
Type IV (usually 24-48 hours after exposure) on the oral mucosa
Who do contact allergies to dental materials affect?
Primarily women
Average age 63 years
What are most common contact allergies to dental materials?
Metals, of which nickel and cobalt were most common allergens
What do denture resins show in dental material allergens?
Mucosal changes, contact stomatitis, and burning sensations of the mouth
Some patients can develop allergic or hypersensitive reactions to even very small quantities of metal such as:
Mercury
Nickel
Cobalt
What can mercury cause to the patient?
direct contact of oral mucosa with this material can cause oral chronic inflammatory lesions on the oral mucosa
What should you ask a patient to see if they are allergic to nickel?
Ask if they can wear costume jewelry
What is this?
Oral lichen planus
What is this?
Amalgam tattoo
What is one of the most common causes of allergic contact dermatitis and produces more allergic reactions than all other metals combined?
Nickel
What are several brands of orthodontic wires made of?
Nickel titanium alloy
What do non-precious metal crowns contain?
High levels of nickel - some as high as 55%
What is this?
Nickel allergy
What is oral allergy syndrome?
Some people with pollen allergies have allergic symptoms around and in the mouth and throat after eating raw fresh fruits, vegetables, nuts, or seeds which contain proteins cross reactive to the pollens
What is this?
Oral hypersensitivity rxn
What is this?
Titanium hypersensitivity
What is sargenti paste for root canals?
Paraformaldehyde
As a dentist, what must you know about materials?
- dental practitioners are responsible for the materials to which a patient will be exposed
- must have knowledge and understanding of the composition of the materials and how they can affect patients
- safest and most effective
- read and understand all inserts that come with materials
What can materials cause?
Irreversible damage causing destruction of CT, bone, nerves, chronic infection and pain
How can material travel?
Throughout the body-blood, lymph nodes, adrenal glands, kidney, brain
What does calcium hydroxide stimulate?
Tertiary dentin formation
Since a restoration may have an adverse effect on the pulp, a range of materials were developed to be applied. What are they?
Intermediate restorative materials (IRMs), applied to dentin prior to the placement of the final restoration
What are examples of intermediate restorative materials?
Cavity varnishes, bases and liners and are intended to remain in place permanently
**these materials shouldn’t be confused with temp restorative materials
What are roles of intermediate restorative materials?
Protective, palliative or therapeutic
What is the goal of intermediate restorative materials?
Protect the pulp from chemical, electrical (galvanic shock - dissimilar metals), thermal
What are examples of intermediate restorative materials?
ZOE - sedative like qualities on hypersensitive pulp and is good thermal insulator as well
What are qualities of intermediate restorative materials?
*Acts as a thermal insulator
*Excellent abrasion resistance
*Good sealing properties
*Low solubility
*May be used under cements and restorative materials that do not contain resin components
What are things to consider when working with intermediate restorative material?
- material should not discolor the tooth or restoration
- should harden quick enough to allow subsequent insertion of the restoration
- should withstand the condensation of the over laying restoration
- should be easily manipulated- what works for you
Where are liners and bases placed?
Between dentin (and sometimes pulp) and the restoration to provide pulpal protection or pulpal response
What do protective needs for a restoration vary depending on?
The extent and location of the preparation and the restorative material to be used
What are characteristics of liners and base selection?
Determined largely by the purpose it is expected to serve
Why are liners and bases not fully distinguishable?
Because they share similar objective/properties
What are bases?
thick mix of material which is placed in bulk
Used as a dentin replacement to minimize final restorative material
Wha are bases used for?
To block out undercuts
Where are liners applied?
As a thin coating over exposed dentin
What are liners used to promote?
Less than 0.5mm thick and is able to promote the health of the pulp by adhesion or antibacterial action
What is the primary role of liners?
To protect the pulp
What bond do liners form?
Strong bond to dentin, preventing fluid movement down the dentinal tubules
What kind of barrier do liners provide?
A bacterial barrier
What release do liners have?
sustained Fluoride
What is vitrebond?
Light Cure Resin-modified Glass Ionomer
Liner/base
What can vitrebond be used under?
composite, amalgam, metal and ceramic restorations
What is vitrebond not indicated for?
NOT INDICATED FOR DIRECT PULP CAPPING
What is the pH of calcium hydroxide?
Ca(OH)2- highly alkaline with a pH of 11-12.5
How long does bactericidal activity retain its anti-bacterial property for?
About 2 months
What do liners help with the formation of?
Tertiary dentin
What are liners used for?
Direct and indirect pulp capping
What is dycal?
Calcium hydroxide liner
How is dycal cured?
Self curing or light cured
What is a varnish?
Natural gum (copal), rosin, or synthetic resin dissolved in organic solvent
What properties do varnishes have?
Antimicrobial and antiviral properties
What do varnishes easily seep into?
Open dental tubules
What do varnishes prevent?
Transfer of heat and cold to the dentin and pulp
What do we use at the school instead of varnishes?
Vitrebond
When should varnishes not be used?
- Under composite restorations (interferes with the setting reaction)
- Under glass ionomers (interferes/prevents fluoride release)
What is copalite used as?
An insulating layer under gold and amalgam restorations
What should you do in a shallow tooth prep?
Place nothing, vitrebond, or varnish
What should you do for a moderate depth prep?
Liners may be placed for thermal protection and pulpal medication along with varnish
What should you do for a very deep prep?
Liner may be calcium hydroxide, then the base vitrebond (glass ionomer) or IRM
