Research library
What the evidence actually says.
Plain-language summaries — never overstated, always distinguishing what was found from what it means for you.
Is there really a link between gum disease and heart disease?
A large body of observational evidence shows a consistent association between periodontal disease and cardiovascular disease, with proposed mechanisms involving chronic inflammation. A 2024 American Heart Association scientific statement described robust evidence that periodontal disease independently increases atherosclerotic disease risk when major cardiac risk factors are controlled for. Most evidence is observational, though — meaning a strong association, not proof of direct causation.
Do asymptomatic wisdom teeth actually need to come out?
The review found only low- to very-low-certainty evidence either supporting or refuting routine preventive removal of symptom-free, disease-free wisdom teeth. One included study suggested a possible small increased long-term risk of gum disease on the neighboring tooth when a wisdom tooth is retained, but that finding was rated very low certainty. The reviewers explicitly could not conclude that removal is clearly better than watchful monitoring for these specific cases.
Which lasts longer: composite (tooth-colored) or amalgam fillings?
Pooled data generally shows amalgam fillings lasting somewhat longer than composite in back teeth — one systematic review reported median survival exceeding 16 years for amalgam versus about 11 years for composite, with composite showing a meaningfully higher failure rate driven mainly by decay at the filling's edges. Amalgam failures, when they happen, are more often due to fracture. Other data suggests the longevity gap has narrowed as composite materials have improved.
Is mercury in amalgam fillings actually a health risk?
Major regulatory reviews, including the FDA's most recent update, report insufficient evidence linking mercury exposure from amalgam fillings to adverse health effects in the general population — including pregnant women and young children — at the low levels typically released (estimated around 0.4-4.4 micrograms per day, well below international exposure limits). A 2014 Cochrane review similarly found insufficient evidence to support or refute adverse effects from amalgam compared with composite. At the same time, amalgam does continuously release small amounts of mercury vapor, which is why some researchers and holistic/biological dentistry practitioners take a precautionary approach favoring mercury-free alternatives, particularly for sensitive populations.
Do electric toothbrushes actually clean better than manual ones?
Powered toothbrushes, particularly those with a rotating-oscillating brush head, showed a statistically significant reduction in plaque and gingivitis compared with manual brushing, both short-term (1-3 months) and long-term (3+ months) — commonly cited around 11-21% greater plaque reduction depending on the specific comparison and timeframe.
How successful are root canals, according to the evidence?
Pooled success rates commonly fall between 82% and 93% at around 10 years, with some reviews reporting tooth survival as high as 97% at 10 years when the tooth was properly restored with a crown afterward. Longer-term data (30+ years) shows success gradually declining but remaining substantial, often cited around 68-81%. Teeth restored with a full-coverage crown after treatment showed meaningfully better long-term survival than teeth left without one.
What does long-term dental implant survival actually look like?
Implant survival commonly exceeds 90% at 10 years across pooled studies, with one 20-year meta-analysis reporting roughly 88% survival at that longer horizon. Survival is generally comparable to — not clearly superior to — well-maintained natural teeth with periodontal or endodontic treatment over similarly long follow-up; one review found long-term tooth-loss and implant-loss rates were broadly similar depending on the specific study.
Does deep cleaning actually help, and does it affect blood sugar too?
SRP is well-established as effective for reducing gum inflammation, pocket depth, and bleeding, regardless of whether it's done full-mouth or quadrant-by-quadrant — both approaches show meaningful improvement. In people with type 2 diabetes, several trials found SRP led to a measurable, short-term reduction in HbA1c (a blood sugar marker) at 3-4 months, though evidence for whether that holds beyond 4 months is inconsistent, and at least one larger trial found no benefit.