Biocompatibility of materials for use in the body Flashcards
What is a biomaterial?
Biomaterials are biological materials either synthetic (ceramics, polymer, metal) or natural that are used as part of an implanted medical device to replace an organ or bodily function.
What are some examples of biomaterials used in dentistry?
- Amalgam
- Glass ionomers
- Gold
- Composites
- Ceramics
- Titanium
- Bone filling products
- Teeth bleaching products
What are 6 different applications of biomaterials?
- Medical implants: Dental implants, heart valves, artificial joints.
- Repair and healing of human tissues: Sutures, clips, staples.
- Cellular scaffolds for regenerating tissues- Biomaterials incorporating cells and bioactive molecules.
- Molecular probes and nanoparticleS: Used for imaging for cancer and to deliver therapies at the molecular level.
- Biosensors: To detect the presence of specific substances and to transmit that data.
- Drug-delivery systems: As carriers of drugs to a disease, target drug-coated vascular stents and implantable birth control and chemotherapy devices for cancer patients.
What are the 4 things dentists must be wary concerning the biocompatibility of materials?
- Safety to the patient
- Safety to the staff
- Regulatory Compliance issues
- Legal liability
Define biocompatibility.
The ability of a material to perform with an APPROPRIATE HOST response in a given SPECIFIC APPLICATION.
Materials used in dentistry come into direct contact with which tissues?
Hard tissues of the teeth
The soft tissue of the oral mucosa
The pulp & periapical tissues
What 6 qualities must materials used in dentistry have?
- Non-toxic (both to the patient and staff)
- Non-irritant (in the mouth and other tissues)
- Minimal inflammation (acute, not chronic)
- Tissue integration (implants)
- Physical and mechanical properties (for intended application)
- Not be mutagenic or carcinogenic
Biologically what occurs when a biomaterial is placed on the body?
- New interface on the body.
- The body’s normal homeostasis is disturbed and a TWO-WAY biological interaction takes place.
- The effect the body has on the implant material
-The effect the implant has on the body
Biocompatibility concerns Interaction between LIVING TISSUE and NON-LIVING.
What are 4 effects the body has on the implant material?
- Protein adsorption - Dependent on material properties.
- Environmental - Body fluid 0.9 saline, plus cells, proteins.
- Degradation - Enzymatic (on certain materials)
- Corrosion - May cause metal to corrode.
What are 5 effects the implant has on the body?
- Blood clot-equilibrium disturbed (registered as injury)
- Inflammatory response (should be short lived).
- Chronic inflammation (if prolonged).
- Evokes immune response (activation of macrophages, lymphocytes)
- Wound healing repair/regeneration
- What in vitro tests can be used to assess biocompatibility?
- Cytotoxic screening tests.
These provide an indication of cell death caused by either the material directly or their extracts.- Cell metabolism
Assesses cell number and growth rate. - Gene-up regulation
See if material causes genes to be up-regulated
l causes genes to be up-regulated
- Cell metabolism
Why is in vitro testing not always comparable to in vivo testing?
As in vitro testing is done in a lab, meaning its static. It is also done in a small volume.
What are the 4 factors influencing biocompatibility?
- Location of material
- Health of the host
- Physical, chemical and biological stresses placed on the material
- Duration of exposure
What is the progression of tests required to test biocompatibility?
- Unspecific Toxicity.In vitro and does not reflect the final material use.
- Specific Toxicity.
In vitro and in vivo and conditions are more relevant to final application (e.g. bone cells) - Clinical trials.
- Specific Toxicity.
how is the measurement of biocompatibility of regulated?
The International Organization for Standardization (ISO) is an international standard-setting body composed of representatives from various national standards organizations.
Look at slide 18
What are the 2 main components of biocompatibility?
- Biosafety (the general aspect)This concerns and deals with the exclusion of deleterious effects of a biomaterial on the organism itself.
- Biofunctionality (the specific aspect)
What is the difference between a direct and indirect in vitro test?
- Direct - Material contacts directly with the cells.
- Indirect - There is a barrier present between the material and the cells.
-What are primary cells?
A cell that has been extracted from a tissue.
What are 3 requirements for biocompatibility in vitro testing methods?
- Specificity - Appropriate cells for material being tested
- Sensitivity - Methods used should be sensitive and suitable for cell culture medium
- Quality controls - Both negative (non-toxic) and positive (toxic) and also, material and cell culture control
What is the procedure that allows materials to be tested on animals and then clinical trials?
- Apply to home office for licence to do animal studies
- If the material has been proven to be non toxic in vitro.
- Then apply for ethics and consent.
- Then you can do clinical trials.
What are the 2 main negative reactions to dental materials?
- Inflammation
- Allergic reaction
What are the 2 less common negative reactions to dental materials?
- Immunotoxicity
- Systemic and local toxicity.
why is RISK IS GREATER TO THE PRACTITIONER THAN THE PATIENT?
Time dependent exposure when material being manipulated or during setting
Inhalation of particulates during surgical procedures can activate immune cells (e.g dust from alginate impression materials, also some products containing lead and tin)
Effects can range from cumulative irritation to severe allergenic responses
Why is there concern over the biocompatibility of amalgam and how is this risk reduced?
- Concern over the mercury vapour released during use.
- Careful handling
What side effects have occured due to amalgam?
Lichenoid episodes.
slide 27
What can incomplete polymerisation lead to in resin based composite fillings?
- Degradation
- Leaching
- Imperfect bonding
- Polymerisation shrinkage
What side effects have occured due to resin-based composites?
- Increased plaque adhesion
- Lichenoid episodes.
- Cytotoxic substances like TEGMA and HEMA can be released from unset or partially cured composites, which can diffuse through the dentine and cause pulpal inflammation.
When can irritation to the pulp occur with glass ionomer cements?
Etching process during placement.
What filling material has the ‘best’ biocompatibility?
Glass ionomer cement.
When do we use gold foil and cast alloys?
Used for making crowns, bridges and dentures
When can gold foil and cast alloys cause potential pulp reactions?
if condensation occurs.
What is a side effect of ceramics?
Wear on opposing dentition and restorations.
Why are all these dental materials deemed to be acceptable for use?
They show biocompatibility with local tissues:
- When properly handled and carefully placed in the oral cavity.
- Adverse systemic reactions are RARE, self-limiting, and tend to be of an allergic nature.
- Local reactions have been documented in only a small percentage of individuals.
