What causes a metallic taste associated with dental fillings and how is it treated?

Metallic Taste from Dental Fillings: Causes and Treatment

Metallic taste from dental fillings is most commonly caused by metal hypersensitivity or corrosion of amalgam fillings, and treatment should focus on identifying the specific cause and replacing problematic fillings with alternative materials when necessary.

Causes of Metallic Taste from Dental Fillings

Mercury Release from Amalgam Fillings

• Dental amalgam fillings (containing approximately 50% metallic mercury) continuously release mercury vapor that can be inhaled and absorbed into body tissues 1
• Studies show that 54.3% of adults with amalgam fillings may be exposed to mercury vapor exceeding California EPA safety limits 2
• Chewing gum significantly increases mercury release from amalgam fillings, with gum chewers showing nearly twice the urinary mercury content (1.36 μg Hg/24h) compared to non-chewers (0.70 μg Hg/24h) 3

Metal Hypersensitivity

• Metal hypersensitivity can develop at any age and has a significantly higher incidence in females 4
• Approximately 10-15% of the population may exhibit an allergy to one or more metals commonly used in dental implants 4
• In a clinical study, 78.9% of patients with oral lichenoid lesions adjacent to amalgam fillings were sensitized to inorganic mercury 5

Galvanic Corrosion

• Contact between different metal restorations (amalgam and other metals) can theoretically increase electrochemically caused amalgam corrosion 3
• However, clinical studies have not demonstrated significant increases in urinary mercury levels from dental contacts between different metal types 3

Symptoms Associated with Dental Fillings

• Metallic taste is reported by 54% of patients with illness attributed to dental fillings 6
• Other common oral symptoms include tender or aching teeth (60%), sore mouth (43%), and dry mouth (43%) 6
• Systemic symptoms reported by patients with concerns about dental fillings include diffuse pain (78%), general weakness (75%), extreme fatigue (68%), and dizziness (68%) 6

Diagnosis and Evaluation

• Patch testing can identify metal allergies, with positive results to inorganic mercury, gold, and palladium being most common 5
• Late readings (10-17 days after application) are important, as 33.3% of positive mercury patch tests were observed only at days 10 or 17 5
• Blood and urine mercury levels can be measured, though patients with symptoms attributed to amalgam fillings often have normal levels (median 10 nmol/L in whole blood and urine) 6

Treatment Approaches

For Metal Hypersensitivity

• Removal of amalgam fillings resulted in healing or significant improvement in 86.7% of mercury-sensitized patients with oral lichenoid lesions 5
• Patients with allergic contact stomatitis caused by gold or palladium showed complete healing after removal of these restorations 5
• For patients with documented hypersensitivity to metals, alternative materials should be considered 4

For Tooth Sensitivity

• Fluoride varnish is recommended as the most effective first-line treatment for tooth sensitivity 7, 8
• Desensitizing toothpastes containing potassium nitrate are effective for mild sensitivity 7, 8
• Professional application of fluoride varnish is recommended for moderate to severe sensitivity 7, 8

For Symptomatic Relief

• NSAIDs (such as ibuprofen) are recommended for acute dental pain, with acetaminophen as an alternative when NSAIDs are contraindicated 7, 8
• Avoiding triggers such as crunchy, spicy, acidic, or hot food/drinks can help reduce sensitivity 7
• Reducing gum chewing can decrease mercury release from amalgam fillings 3

When to Seek Dental Care

• Immediate referral is necessary for severe pain or significant oral symptoms 7, 8
• Referral within a few days is recommended for moderate sensitivity that doesn't respond to over-the-counter treatments 8
• Patients with suspected metal allergies should be evaluated with appropriate patch testing 5

Important Considerations

• The relationship between amalgam fillings and systemic symptoms remains controversial, with some studies suggesting multiple explanations for patient complaints beyond mercury release 6
• Psychological factors may play a role in some patients with multiple symptoms attributed to dental fillings 6
• Proper dental hygiene and regular dental check-ups are essential for all patients with dental restorations 4