Adverse reactions to dental materials Flashcards
What the clinician expects of their dental materials (5)
Ease-of-use.
Appropriate physical/mechanical properties.
Cost-effective biomaterials & devices
Efficacy.
Safety - for the patient & the dental team
What do we mean by ‘safe’?
“Biocompatible materials do not irritate the surrounding structures, do not provoke an inflammatory response, do not incite allergic reactions, and do not cause cancer”
Types of toxic and adverse reaction (3)
Toxicity.
-cytotoxicty / genotoxicity / mutagenicity/carcinogenicity / teratogenicity / neurotoxicity / metabolic toxicity
Allergic reactions.
-immediate (type I hypersensitivity).
-delayed (type IV hypersensitivity)
Irritant (non-allergic) reactions or intolerance?
Hazards found in dental materials (2)
130 common allergens present in dental materials. Kanerva L, et al. 1995 in “Practical Contact Dermatitis” ed. JD Guin, McGraw-Hill.
26% of 219 substances identified in dental materials had risk or safety phrases in their materials safety data sheets (MSDS).
Adverse reaction to biosynthetic hyaluronic acid gel (case report) (4)
3% of patients experience allergic reactions to implanted bovine collagen.
HYA is believed to be non-immunogenic.
Case study patient developed allergic-type reaction after third treatment.
Not known if this is reaction to a modified HYA or a contaminant.
Allergic and adverse reactions are mostly published in which form? (4)
Most published studies are in the form of case reports.
Case reports are at best based on patch testing for likely allergens, but often lack detailed investigation.
Some adverse reactions are a response to the physical form of a materials.
Local inflammation is a normal reaction to common degradable medical polymers and some biological materials (not an allergic reaction).
Synthetic biomaterials: failure via chronic inflammation (3)
Many medical devices have a finite life due to aseptic inflammation
Early artificial TMJ was disastrous (Vitek®) - similar mechanism.
Foreign body response to physical presence of particulate debris (irritant).
How common are real adverse reactions to biomaterials? (3)
Generally, allergy rates (e.g. hay fever) are increasing.
Innovation means that dental materials are increasing in range and complexity.
Exposure increases risk
Adverse reactions: the UK experience (3)
UK Adverse Reaction Reporting Project (ARRP) set up at the University of Sheffield in 1998. 786 reports processed 1998-2002.
Obtained information on adverse reactions to dental biomaterials via survey and web reporting.
Database modelled on Adverse Reaction Unit of the University of Bergen in Norway:
Bergen Unit still very active, despite evidence that dental materials are largely safe. Much of its research contradicts media “scare” stories on phantom risks
Risk reduction (4)
- European regulations: Pre-market testing & the CE mark
- Responsible manufacturing by industry, e.g. improved packaging
- Non-contact operative techniques
- Post-market surveillance
- via Competent Authority (MHRA) due to European regulations.
- via research projects (e.g. Adverse Reaction Units of Bergen University and Sheffield)
Pre-market testing (7)
Required by law for new biomaterials
Tests based on ISO 10993 guidelines
Exact tests determined by evaluation of risks associated with the material and its clinical application.
Tests include cytotoxicity, haemolysis, irritation, systemic toxicity, & genotoxicity
Manufacturers work with a Notified Body to satisfy a Competent Authority that a medical device (e.g. dental biomaterial) is safe and fit for purpose.
New devices are then awarded a CE mark for sale in Europe / EFTA
All developed nations operate a similar regulatory system (e.g. US FDA).
CE mark (3)
The award of a CE mark enables goods to be sold throughout the EEA.
It is the result of a risk management exercise including scientific, pre-clinical and sometimes clinical testing.
However, “no amount of experimental study can guarantee the absolute safety of any substance”
Packaging and non-contact operative technique (2)
Early packaging materials were associated with drips and spillage that could contact skin or gloves (that do not protect against many chemicals including resins)
Manufacturers have taken steps to protect the dental team from physical contact with their products with no-drip packaging and dispensers
Why monitor? The role of post-market surveillance (3)
It provides an “early warnings” of previously unsuspected adverse reactions.
It can be used to identify factors associated with particular adverse reactions.
It permits continued safety monitoring throughout the duration of a product’s use on the market
