Dentists weigh in on hydroxyapatite as fluoride alternative

Dr. Jin-Ho Phark, an associate professor of clinical dentistry at the University of Southern California, reports a steady increase in patients inquiring about toothpaste formulations that exclude fluoride. He attributes the surge in interest to social media influencers heavily promoting a calcium phosphate mineral known as hydroxyapatite.

Fluoride toothpaste became the industry standard in the late 1950s when Procter & Gamble Co. introduced Crest nationally. For decades, the mineral served as the primary active ingredient in oral care products to protect tooth enamel from bacteria. Today, health officials and dentists generally agree that low levels of fluoride are safe and effective for cavity prevention.

Skepticism toward fluoride has grown, fueled in part by comments from Health Secretary Robert F. Kennedy Jr. He has linked water fluoridation to conditions ranging from arthritis and bone fractures to neurodevelopmental disorders and thyroid disease. While Bennett Amaechi, a professor of dentistry at the University of Texas at San Antonio, notes that no concrete evidence links standard fluoride levels to lower IQs in children, the controversy has created market space for hydroxyapatite alternatives.

Hydroxyapatite shares a chemical structure with tooth enamel, which is composed primarily of calcium and phosphate. Proponents argue the mineral can help remineralize teeth and reduce sensitivity. Many commercial products use nano-hydroxyapatite, featuring particles small enough to theoretically penetrate pores in the enamel, although clinical data on this specific mechanism is still limited.

Amaechi, who studies the mineral, states that early research indicates hydroxyapatite is as effective as fluoride in preventing caries. He co-authored a 2021 study in Scientific Reports that monitored 177 children for nearly a year. The researchers found similar outcomes in tooth decay between groups using hydroxyapatite and those using fluoride. That study received funding from Dr. Wolff Group, a German manufacturer of two hydroxyapatite brands.

A subsequent study published in 2023 in Frontiers in Public Health tracked 171 adults for 18 months. The participants, who were mostly healthy young adults with few oral health issues, showed comparable decay rates in both groups. The study was also funded by Dr. Wolff Group. A separate 2019 study in the Journal of Investigative and Clinical Dentistry included 133 individuals at higher risk for caries and found similar performance between the two toothpaste types after five months.

Dr. Livia Tenuta, an associate professor at the University of Michigan School of Dentistry, cautions that most existing studies rely on participants with low risk for tooth decay. She recommends waiting for more long-term research, particularly on populations prone to cavities, before declaring the mineral a definitive replacement for fluoride.

The American Dental Association acknowledged the rising use of hydroxyapatite products in an email. Dr. Ada Cooper, the association's Consumer Advisor, noted that while some evidence supports the mineral's ability to contribute to remineralization, its clinical effectiveness remains limited and ambiguous. The ADA continues to recommend brushing twice daily for two minutes with fluoride toothpaste.

Hydroxyapatite toothpastes typically cost more than fluoride options, with some products priced over a dollar more per ounce. Amaechi advises patients open to both choices to stick with fluoride due to its extensive history of long-term research. Tenuta agrees, citing the volume of evidence behind the traditional ingredient.