Tooth sensitivity affects 7 in 10 adults — and a toothpaste ingredient may be the fix

Hydroxyapatite plugs exposed dentinal tubules to block pain signals

Bukwang Pharmaceutical's Sirinmed shows 92% improvement in clinical trials after four weeks

Low abrasion score of 7.8 minimizes enamel damage while promoting remineralization

A sharp, stinging sensation when cold air hits the teeth or a cold drink passes over them is one of the most common oral health complaints among adults, affecting roughly seven in 10. Known clinically as dentin hypersensitivity, the condition begins when the gums recede or the enamel on the tooth surface is damaged — typically through improper brushing technique, aging, or periodontal disease.

Once the protective outer layer wears away and the underlying dentin is exposed, microscopic channels called dentinal tubules open to the surface. Temperature changes or physical contact cause the fluid inside those tubules to shift rapidly, stimulating the pulp nerve and triggering sharp pain. According to the hydrodynamic theory widely accepted in dentistry, physically or chemically sealing the exposed tubule openings is the key to treating tooth sensitivity.

That is where hydroxyapatite (HAp) comes in. Hydroxyapatite is a biocompatible mineral whose chemical composition is identical to that of natural human teeth and bone. Microscopic hydroxyapatite crystals penetrate the exposed tubules, fill in micro-defects directly, and form a protective layer that blocks the pathway through which external stimuli reach the nerve.

Sirinmed F. [Provided by Bukwang Pharmaceutical]

In South Korea, Bukwang Pharmaceutical's Sirinmed — the country's leading sensitivity-specific toothpaste — is widely cited as a prime example of this mechanism in action. A domestic clinical trial conducted at the Department of Periodontology at Kyung Hee University's College of Dentistry found that patients using Sirinmed, which contains hydroxyapatite as its main active ingredient, reported improvement in sensitivity symptoms in 89 percent of cases after two weeks and 92.4 percent after four weeks.

Abrasion management is equally critical for sensitivity toothpastes. Prolonged use of a highly abrasive formula can wear down hard tooth tissue further, worsening symptoms. Under the British Standards Institution's abrasion scale, where 100 is the reference point, conventional toothpastes typically score between 80 and 100, while Sirinmed scores just 7.8 — minimizing enamel damage while coating the dentinal tubules.

Research from domestic and international academic institutions further supports hydroxyapatite's efficacy. A randomized controlled trial by periodontology researchers at Yonsei University and Seoul National University's dental hospitals found that a hydroxyapatite toothpaste produced pain reduction — measured on a visual analog scale — comparable to strontium chloride, a conventional desensitizing agent. A double-blind randomized controlled trial by an Italian research team, published in the journal Clinical Oral Investigations, also found that a 2 percent nano-hydroxyapatite formulation produced statistically significant pain relief against both cold-air and tactile stimuli compared with a control group at both the two-week and four-week marks.

Beyond pain relief, hydroxyapatite also supports remineralization — the process of restoring minerals to the tooth surface. Research at Kyungpook National University's College of Dentistry found that applying micro-hydroxyapatite to artificially demineralized enamel reinforced calcium and phosphate to a depth of 100 micrometers below the surface, restoring damaged enamel rods. A separate study at Yonsei University's College of Dentistry found that combining nano-hydroxyapatite with fluoride produced a synergistic remineralization effect, contributing to the suppression of tooth decay.

Experts stress that early management is essential, as untreated sensitivity can progress to nerve damage or chronic pain. Scrubbing the teeth vigorously from side to side can carve V-shaped grooves at the gumline — a condition called cervical abrasion — that accelerates tubule exposure. Dentists recommend using a soft-bristled, small-headed toothbrush and adopting a habit of applying a sensitivity-specific toothpaste such as Sirinmed directly to the affected area with a fingertip, massaging gently for about one minute before brushing.

silverpaper@heraldcorp.com