Shark Teeth and Human Dental Biology
What shark research can—and cannot—tell us about human teeth, tooth replacement, and preventive dental care.
Shark teeth are interesting models for studying biology, but they are not a guide to treating human teeth. Research into tooth development does not mean people can replace lost adult teeth naturally or skip ordinary preventive care.
Can shark research explain how human teeth developed?
It can help researchers ask questions, but comparisons need care. A 2021 study led by the University of Bristol and the Naturalis Biodiversity Center examined 415-million-year-old fossils of acanthodians, early relatives of sharks. It found that the teeth of living sharks do not represent the ancestral dentition of all jawed vertebrates. Complex arrangements of teeth have been gained and lost many times through evolutionary history, so tooth replacement in living sharks is not the most direct model for human dental problems.
Does this mean tooth regeneration is a treatment option?
No. The evolutionary study does not establish a treatment for patients. If you have a missing or damaged tooth, decisions should start with an examination and the options appropriate for your mouth. Our guide to dental implants explains one replacement option, and a crown may be considered for some damaged teeth.
What is the practical lesson for your teeth?
Focus on protecting the teeth you have. Use fluoride toothpaste appropriate for your needs, clean between your teeth, and arrange regular dental examinations. Biology research can improve understanding without changing what an individual patient needs today.
At our San Marco office in Jacksonville, an examination connects your symptoms, medical history and dental findings to a treatment plan. Contact CJ Henley, DMD if you have a tooth concern.
Sources
Rücklin M, King B, Cunningham JA, Johanson Z, Marone F, Donoghue PCJ. Acanthodian dental development and the origin of gnathostome dentitions. Nat Ecol Evol. 2021;5(7):919-926. doi:10.1038/s41559-021-01458-4. Retrieved via PubMed.
University of Bristol. New study sheds light on the deep evolutionary origins of the human smile. May 6, 2021. Retrieved October 6, 2026.
About the author. CJ Henley, DMD, is a general dentist in Jacksonville whose practice focuses on cosmetic and restorative dentistry, dental implants and dental care around head and neck cancer. Meet Dr. Henley.
CJ Henley, DMD, PA · 3675 Hendricks Avenue, Jacksonville, FL 32207 · 904-398-1549
Updated October 2026.
Do Unused Dental Benefits Expire at the End of the Year?
When it comes to dental benefit plans, millions of people each year are ringing in the New Year leaving money on the table. According to the National Association of Dental Plans, only 2.8% of people with PPO dental plan participants reached or exceeded their plans annual maximum. Many people also have Flexible Spending Accounts, which help pay for dental and medical care with pre-tax dollars.
For most dental plans, yes. Your annual maximum resets when the plan year ends, often December 31, and unused benefits usually do not roll over. Money in a health flexible spending account (FSA) is also lost at the end of the plan year unless your employer offers a carryover of up to $680 for 2026 plan years or a grace period of up to two and a half months. Check your own plan's dates, and let your dental needs, not the calendar, decide what treatment you have.
When does my dental plan year end?
Many dental plans run on the calendar year, but some follow a different 12-month cycle tied to your employer's benefits year. Your plan document, your benefits office or the member services number on your insurance card can tell you:
when your plan year ends
how much of your annual maximum you have used
whether any treatment has a waiting period or frequency limit
How can I make the most of my dental plan?
Keep up with checkups and cleanings. Many plans cover routine exams and cleanings at a higher level than other treatment. Check your plan for the exact coverage.
Plan in the summer or early fall. If a checkup shows that you need treatment, ask about timing then. Appointments fill quickly in November and December.
Let the clinical need set the schedule. Some treatment can safely be staged across two plan years, and some should not wait. I will tell you which is which. A benefit deadline is never a good reason to start treatment you do not need.
How do FSAs work for dental care?
A health FSA is an account you set up through your employer. You choose an amount during open enrollment, and it is taken from your paychecks before taxes. For plan years beginning in 2026, the IRS limit is $3,400 per employee.
FSA money can generally be used for dental care that treats or prevents disease, such as exams, cleanings, fillings, crowns, dentures and orthodontic care needed for dental health. Purely cosmetic procedures, such as teeth whitening, generally do not qualify. Your FSA administrator has the final list of eligible expenses.
What happens to unused FSA money?
Generally, you must use FSA money within the plan year. Your employer may offer one of two options, but not both, and is not required to offer either:
A carryover. You can carry unused money into the next plan year. For 2026 plan years, the maximum carryover is $680.
A grace period. You get up to two and a half extra months after the plan year ends to use the money.
Anything left after the deadline is forfeited. Your employer or FSA administrator can tell you which option, if any, your plan offers.
Does our office work with my dental insurance?
We are an out-of-network practice. We can help you understand how to use your benefits. You are responsible for amounts your plan does not pay. To learn how out-of-network benefits are usually calculated, read what patients should know about out-of-network dental insurance. If you are planning around retirement or a change in coverage, see retirement and dental insurance.
Planning care before the year ends
If you have not had a checkup this year, or you have treatment you have been putting off, now is a good time to ask about scheduling. New patients start with a comprehensive dental exam. You can reach our Jacksonville office through our contact page or at 904-398-1549.
Sources
Internal Revenue Service. Rev. Proc. 2025-32 (health FSA limit $3,400 and maximum carryover $680 for plan years beginning in 2026). Retrieved October 6, 2026.
Internal Revenue Service. IRS releases tax inflation adjustments for tax year 2026 (IR-2025-103, October 9, 2025). Retrieved October 6, 2026.
HealthCare.gov. Using a Flexible Spending Account (FSA) (grace period of up to 2½ months, or a carryover, but not both). Retrieved October 6, 2026.
Internal Revenue Service. Publication 502, Medical and Dental Expenses (teeth whitening not includible).
About the author. CJ Henley, DMD, is a general dentist in Jacksonville whose practice focuses on cosmetic and restorative dentistry, dental implants and dental care around head and neck cancer. Meet Dr. Henley.
CJ Henley, DMD, PA · 3675 Hendricks Avenue, Jacksonville, FL 32207 · 904-398-1549
Updated October 2026.