Do Humans Have a Third Set of Teeth

Short answer

• No. Humans normally have two sets of teeth: 20 primary teeth, often called baby teeth, in childhood, and 32 permanent teeth in adulthood, including four wisdom teeth. A third set is not a normal stage of development, and no third set should be expected to grow on its own. The phrase third set comes from research language, not from normal anatomy. Researchers use the term third dentition for tooth forming potential that can appear beyond the primary and permanent sets. In humans that potential is usually described as rudimentary, meaning it begins to form early in development and then normally regresses. It is not evidence that every adult carries a complete spare set of teeth waiting in the jaw. A Japanese research program is testing whether that potential can be activated with a drug. The experimental antibody, code named TRG035, blocks a protein called USAG-1 that suppresses tooth development. In animals, blocking USAG-1 restored missing teeth in mice bred to lack them and produced an extra tooth in young ferrets. In people, the first trial was a small safety study, and no published result shows that the drug has grown a tooth in a human. The drug is not an available treatment, and anyone missing teeth now should discuss proven replacement options with a dentist rather than wait for it. This article is general information only. It does not diagnose tooth development conditions or recommend a treatment for any individual. Missing, extra, or unusually positioned teeth need an individual dental assessment.

The Two Sets Humans Normally Have

Humans are diphyodont, which means we normally develop two successive sets of teeth. The first set is the primary dentition. Children normally have 20 primary teeth. They begin to appear in infancy, they hold space for the developing permanent teeth, and they are gradually shed as permanent teeth erupt, mostly during childhood and into early adolescence.

The second set is the permanent dentition. Adults normally have 32 permanent teeth, including four wisdom teeth, which are the third molars. That total is a norm, not a guarantee for every person. Some adults never develop some or all wisdom teeth. Some are born missing other permanent teeth, a condition covered below. Some lose permanent teeth to decay, gum disease, or injury. None of those variations means a third set is developing. Wisdom teeth in particular are part of the permanent set, not a separate third set, even though they usually arrive last.

Permanent teeth do not regrow if they are lost. That single fact explains most of modern replacement dentistry. When a permanent tooth is missing, the choices today are prosthetic, meaning an artificial replacement, or preventive, meaning protecting the teeth that remain. Readers who want the wider body context for how teeth sit alongside other structures can start with the anatomy and organs of the human body, but the dental point is simple. The mouth is built for two sets, and the second set has to last.

If you count teeth and find an extra tooth, a missing tooth, or a tooth erupting in an unusual position, counting alone cannot tell you why. It could be a normal variation, a retained primary tooth that never shed, an extra tooth, or a sign of a developmental condition. A dentist can examine the teeth and, where needed, use imaging to see teeth that have not erupted.

What People Mean by a Third Set of Teeth

When researchers say third dentition, they are describing a developmental possibility, not a set of finished teeth hidden under the gums. A 2023 review by Ravi and colleagues, from the research group at Kitano Hospital in Osaka and Kyoto University, published in Regenerative Therapy, explains the idea this way. The third dentition begins to develop from tissue associated with the developing permanent tooth, and in humans it usually regresses and disappears during development. A rudimentary epithelial form of the third dentition has been identified in humans, and studying it in early childhood helps researchers understand how extra teeth form.

That wording matters, because headlines often turn it into a stronger claim than the review makes. The evidence points to occasional tooth forming potential that can produce one or more extra teeth in some people. It does not establish that every person retains a full third row of usable buds into adulthood, ready to replace any tooth that is lost. Whether an adult who lost a tooth to decay still has usable third dentition tissue at that site is an open research question, not an established fact.

Two observations support the narrower claim. First, some people do grow extra teeth beyond the normal two sets, and the Kyoto and Osaka group has traced some of those extra teeth, on imaging, to this third line of development. Second, in mice, removing the brake on this developmental pathway can rescue tooth germs that would otherwise have stopped developing, a result covered in the animal section below. Neither observation turns the third dentition into a normal human stage. A useful comparison is the broader research survey in can scientists regrow human teeth, which covers this same pathway alongside other regeneration approaches and reaches the same cautious conclusion about human evidence.

Extra Teeth Are Not a Third Set

The condition of having extra teeth is called hyperdontia, and the extra teeth themselves are called supernumerary teeth. Cleveland Clinic describes hyperdontia as uncommon, representing about 1 percent to 3 percent of dental abnormalities, affecting up to 3.8 percent of permanent teeth and up to 0.6 percent of primary teeth, and occurring about twice as often in males as in females. Most cases involve a small number of extra teeth, not a complete additional set.

Hyperdontia shows that human tooth development can, in some people, produce more teeth than usual. It does not show that a full third set is a normal pattern waiting to happen. Extra teeth are not automatically helpful, either. Depending on position, an extra tooth can crowd neighboring teeth, block a permanent tooth from erupting normally, affect the bite, or need monitoring or removal. A tooth that looks like a third row is usually extra teeth, crowded teeth, or teeth erupting in an unusual position, and it needs a dental examination rather than a label based on appearance.

The opposite problem also exists, and it is the one the Japanese drug program targets first. Tooth agenesis means one or more teeth never form. The standard terms sort it by number, excluding wisdom teeth. Hypodontia is the absence of fewer than six teeth. Oligodontia is the absence of six or more teeth. Anodontia is the absence of all teeth. Those definitions come from the peer reviewed tooth agenesis literature and they matter for reading trial announcements, because the first patient trial described below is limited to the severe end of that scale.

How Teeth Develop, and Where USAG-1 Fits

A tooth begins as a tooth germ, a small cluster of developing tissue, long before anything erupts. The 2021 Science Advances paper that anchors this field explains that tooth formation is regulated by signals passing between two tissue layers, the epithelium and the mesenchyme. Among the signaling systems involved are bone morphogenetic protein, called BMP, and Wnt. Positive and negative loops among those signals help decide whether an individual tooth germ keeps developing, and how many teeth form.

USAG-1 is one of the brakes in that system. The Science Advances abstract states the core finding plainly. USAG-1 deficiency leads to enhanced BMP signaling, leading to supernumerary teeth formation. USAG-1 inhibits both Wnt and BMP signals, by binding directly to BMP and by binding to LRP5/6, the co receptor that Wnt signaling uses. The research hypothesis followed from that biology. If USAG-1 normally suppresses the development of potential tooth germs, then blocking USAG-1 might release a germ that had stalled, or allow an additional germ to develop.

The detail that made the approach plausible, rather than reckless, was selectivity. BMP and Wnt signaling are needed well beyond teeth, in the growth of many organs and tissues. The Kyoto University summary of the 2021 study notes that several antibodies against USAG-1 led to poor birth and survival rates in mice, which underlined that risk. One antibody, however, disrupted the interaction of USAG-1 with BMP only, leaving the LRP5/6 interaction alone. That narrower action is the design idea behind the whole program: lift the BMP brake on tooth development without disturbing the other pathway in the same way.

What the Animal Studies Actually Showed

The animal evidence comes mainly from one peer reviewed study: Murashima-Suginami and colleagues, Anti-USAG-1 therapy for tooth regeneration through enhanced BMP signaling, Science Advances, 2021. It is strong animal evidence and, at the same time, only animal evidence. Its results should be stated exactly.

In mice, blocking USAG-1 in two different ways relieved congenital tooth agenesis. Removing the USAG-1 gene, and giving an anti-USAG-1 antibody, both restored teeth in mouse models carrying different genetic defects that normally leave them missing teeth. The paper reports that a single systemic administration of a neutralizing antibody was enough to generate a whole tooth in the mouse work. It also reports an important limit. The antibody did not rescue every feature of every genetic model. In one model it restored teeth without correcting a cleft palate, while gene removal affected the palate through the other signaling pathway. The authors concluded that the causative gene behind a person’s tooth agenesis may act as a biomarker for selecting who could benefit, which is a warning against assuming one drug fits every cause of missing teeth.

In ferrets, the same paper reported a supernumerary tooth in the upper front teeth, described as like the third dentition. Ferrets matter because, like humans, they are diphyodont animals with a similar dental pattern. The conditions needed to get that result also matter, and headlines usually omit them. The ferrets were young, treated in the first weeks of life. Producing the extra tooth took a five times higher concentration of the antibody, three administrations, and drugs to suppress the immune system. The authors themselves wrote that clinical application would require further investigation in other non rodent models. Nothing in the ferret work showed that an adult animal, let alone an adult person, could replace a tooth lost to decay or injury.

Kyoto University, reporting the study in 2021, quoted lead author Katsu Takahashi, then a senior lecturer at the Kyoto University Graduate School of Medicine, saying the team knew that suppressing USAG-1 benefits tooth growth, and that what they did not know was whether it would be enough. That remains the honest summary of the animal phase. It was enough to justify careful human trials. It was not proof of a human treatment.

The Drug Program: Toregem Biopharma and TRG035

The human drug grew out of that laboratory work. Toregem BioPharma is a Kyoto University spinout company, founded on May 12, 2020, headquartered in Kyoto, and set up to develop tooth regenerative medicine. The research leadership is associated with Katsu Takahashi, head of dentistry and oral surgery at the Medical Research Institute Kitano Hospital in Osaka, working with Kyoto University.

The candidate drug is TRG035. Toregem describes it in its August 17, 2026 announcement as the world’s first antibody drug that neutralizes USAG-1, the protein that suppresses tooth development, and says the antibody is expected to activate dormant tooth buds and promote the eruption of new teeth. The word expected is the company’s own, and it is the right word. Expectation is what a trial tests. It is not a result.

TRG035 is given intravenously in the trials described below, as a single dose in the first human study. It is an investigational drug. It is not approved in Japan, the United States, or anywhere else, it is not sold, and it cannot be obtained as a treatment outside a clinical trial. Any offer to sell it as a treatment should be treated as false.

Human Trials, Stated Precisely

This is the section where accuracy matters most, because coverage of this program often merges separate stages into one announcement. As of the latest primary update opened for this article, dated August 17, 2026, the position is as follows.

The first human study was a Phase I safety trial at Kyoto University Hospital. It was a randomized, double blind, placebo controlled, single dose study in 30 healthy adult men aged 30 to 64, each missing at least one molar. It began in 2024, with a planned run from September 2024 to August 2025. Its purpose was safety and tolerability, along with how the drug moves through the body and whether participants developed antibodies against it. Tooth growth was not its measured outcome, and it was never designed to prove that teeth regrow in people.

That Phase I trial is now complete. In an announcement dated November 27, 2025, about a meeting with the United States Food and Drug Administration, Toregem said it had finished the Phase I trial, confirming its safety. Two cautions belong with that sentence. First, confirming safety is the developer’s statement about its own trial. Second, detailed Phase I results, including dose by dose findings, have not been published in a peer reviewed journal and were not posted as results on the trial registry in the reporting opened for this article. A completed safety trial with unpublished detail is real progress. It is not evidence that a single human tooth has grown.

The next study is a Phase IIa trial, and as of August 17, 2026 it had not started dosing patients. On that date Toregem announced that Japan’s Pharmaceuticals and Medical Devices Agency, the PMDA, had completed its required investigation of the clinical trial notification for the Phase IIa study, protocol TR-002. The announced design is an open label, non comparative, multicenter, dose finding trial in 24 children with severe congenital partial anodontia. Toregem stated that, after review by the institutional review board at the trial site, it planned to enroll subjects and begin administering the drug. In other words, a regulatory notification step was complete, hospital ethics review was still to come, and no child had been dosed under that announcement.

Two regulatory milestones sit alongside the trials, and neither is an approval. On September 29, 2025, TRG035 was designated an orphan medicinal product by Japan’s Ministry of Health, Labour and Welfare for severe congenital partial anodontia. Orphan designation supports development for a rare condition. It does not mean the drug works, and it does not make it available. In November 2025, Toregem also received an official Food and Drug Administration response following pre IND meetings about United States development. A pre IND response is an early step in a regulatory conversation. It is not a United States trial authorization and not an approval.

On timing, developers have discussed around 2030 as an aim for first availability, beginning with congenital tooth loss. That is a company goal, not a promised date. Reaching it would require the Phase IIa trial to show that teeth actually form in children, a larger later phase trial, and regulatory approval, none of which has happened yet. Any report that treats 2030 as a scheduled launch, or that describes the drug as available, is ahead of the primary record.

Who This Research Is For First

The first patients are not adults who lost teeth to decay, gum disease, or injury. They are children born missing many permanent teeth. Severe congenital partial anodontia, the Phase IIa target condition, corresponds to the severe end of tooth agenesis, described in developer and regulatory material as missing six or more permanent teeth from birth.

That focus is deliberate, for two reasons. The biology fits first. A child born missing teeth because a tooth germ stalled during development is the closest human match to the mouse models the drug rescued, and a young, still developing jaw is where third dentition tissue is most plausible. The clinical need also fits. Toregem explains that children with congenital anodontia live with missing teeth while the jawbone is still growing, a period when dentures and dental implants are difficult to apply, and that missing teeth then affect chewing, speech, appearance, and nutrition.

For everyone else, the honest position is later, if ever. Toregem says it also envisions, in the future, addressing acquired tooth loss from causes such as cavities and periodontal disease, and researchers have discussed studying other causes of tooth loss after the congenital program. A future vision in a company announcement is not a trial, an indication, or a timeline. Nothing in the current program tests TRG035 in an adult who lost a tooth years ago, and no result shows it can work in that setting.

Why Waiting Is the Wrong Plan for Missing Teeth Now

A missing permanent tooth is not a neutral gap that can simply wait for better science. The American Dental Associations MouthHealthy resource on missing teeth states that remaining teeth may shift, and that in some cases bone loss can occur around a missing tooth. Its listed replacement options are bridges, dentures, and implants, with implants described as most similar to a natural tooth, and it advises talking to a dentist about which option is best for you. That remains the complete menu of proven options today.

Delay carries its own costs. Shifting teeth can change the bite and make cleaning harder. Bone loss around a gap can narrow later treatment choices. Chewing and speech can suffer, particularly with several missing teeth. Those changes develop over months and years, on a timescale far shorter than the remaining trial program for an experimental drug whose first patient study has not yet dosed a child.

The same logic applies to warning signs in the teeth you still have. Gum problems caught early are more treatable, which is why the signs of gum disease are worth knowing before pain forces the issue. Keeping to the visit interval your own dentist sets, rather than a generic schedule, is the subject of how often should you go to the dentist, and pain from cold food has its own causes and fixes, covered in sensitive teeth and ice cream. Protecting a natural tooth you still have is worth more today than any possible future regrowth.

Daily protection is unglamorous and effective. Brush twice a day with fluoride toothpaste, clean between teeth daily, and attend dental visits at the interval your dentist recommends. The plaque to tartar to gum disease sequence behind that advice is the same in principle for the family pets many readers live with, which our guide to pet dental care, cat teeth cleaning, and dog bad breath explains from the veterinary side. In both cases, prevention works now, while regeneration, for humans, remains a research question.

How This Article Differs From Broader Tooth Regrowth Science

Tooth regrowth is an umbrella headline covering several different sciences, and judging any one claim means separating them. The USAG-1 antibody approach in this article aims to release a stalled or dormant tooth germ so a whole tooth develops. Enamel repair research is different. It works on the surface of a tooth that already exists, and it is covered separately in the gel that regrows tooth enamel. Stem cell approaches are different again, building tooth structures from cells rather than releasing a germ that is already present.

When a new headline appears, three questions sort it quickly. Was the result in animals or in people? If it was in people, was the trial measuring safety or measuring whether teeth grew? And who was it tested in: a child born missing teeth, or an adult who lost one? Applied to TRG035 today, those answers are animals for regrowth, safety for the completed human trial, and children born missing many teeth for the next planned trial. That is a genuinely promising research program, stated at its real size.

Frequently Asked Questions

Do humans have 3 sets of teeth?

No, not as a normal pattern. Humans normally have two sets: 20 primary teeth in childhood and 32 permanent teeth in adulthood, including wisdom teeth. Researchers use the term third dentition for limited tooth forming potential beyond those two sets, which usually regresses during development. It is not a normal third set that grows on its own.

Do humans have a third set of teeth naturally?

For the vast majority of people, no third set appears naturally. A small number of people develop one or more extra teeth, called supernumerary teeth, in a condition called hyperdontia. That is an individual variation, affecting up to about 3.8 percent of permanent teeth on Cleveland Clinic figures, not a full third set, and extra teeth can cause crowding or blocked eruption and may need removal.

What is the third set of teeth called?

Researchers call the developmental potential a third dentition. Extra teeth beyond the normal sets are called supernumerary teeth. A person born missing teeth has tooth agenesis, called hypodontia when fewer than six teeth are missing, oligodontia when six or more are missing, and anodontia when all teeth are missing, in each case excluding wisdom teeth.

What is the Japan tooth regrowth drug?

It is TRG035, an experimental antibody drug developed by Toregem BioPharma, a Kyoto University spinout, from research led by Katsu Takahashi of Kitano Hospital in Osaka and Kyoto University. It neutralizes USAG-1, a protein that suppresses tooth development by inhibiting BMP and Wnt signaling, aiming to allow a dormant or stalled tooth bud to develop. It is given intravenously in trials and is not an approved or available treatment anywhere.

Has the drug grown teeth in people?

No published result shows that. Blocking USAG-1 grew teeth in mice and produced an extra tooth in young ferrets, in work published in Science Advances in 2021. The completed human Phase I trial, in 30 healthy men aged 30 to 64 who were each missing at least one molar, measured safety, not tooth growth. The developer says that trial confirmed safety, but detailed results have not been published. The first trial designed to test dosing in patients, a Phase IIa study in 24 children born missing many teeth, had not started dosing as of the developer’s August 17, 2026 announcement.

When will a tooth growing drug be available?

No date can be promised. The developer has discussed around 2030 as an aim, first for people born missing many teeth. Before any availability, the Phase IIa trial would need to show teeth forming in children, a larger trial would need to follow, and regulators would need to approve the drug. If you are missing teeth now, that timeline is a reason to use proven options, not to wait.

Should I wait for the drug instead of getting an implant, a bridge, or dentures?

Waiting is generally not advisable. The American Dental Association notes that remaining teeth may shift and bone loss can occur around a missing tooth, and those changes can limit later options. Implants, bridges, and dentures are the proven replacements available today. A dentist can advise which fits your mouth, health, and budget after an examination. The experimental drug has not been shown to grow teeth in people and is being developed first for children born missing teeth, not for adult tooth loss.

What should I do about missing or extra teeth right now?

Book a dental examination. A dentist can assess bone, gums, neighboring teeth, and bite, check for teeth that have not erupted, and discuss replacement or monitoring. Seek care promptly for a loose, painful, broken, or infected tooth, or for swelling. For a child who is missing teeth, has extra teeth, or has teeth erupting in an unusual pattern, ask a dentist or pediatric dentist for an early assessment, because timing during growth affects the plan.

Sources & references

• Murashima-Suginami, A., Kiso, H., Tokita, Y., and colleagues, including Takahashi, K. Anti-USAG-1 therapy for tooth regeneration through enhanced BMP signaling. Science Advances, 2021, volume 7, issue 7, article eabf1798. Peer reviewed primary study. USAG-1 deficiency and supernumerary teeth, antibodies interfering with USAG-1 binding to BMP but not LRP5/6, rescue of congenital tooth agenesis in mice by gene removal and by antibody, a single systemic administration generating a whole tooth in mice, and a supernumerary upper incisor like the third dentition in postnatal ferrets under higher dose, repeated administration, and immunosuppression. Opened and read first hand on November 3, 2026, via PubMed Central, PMC7880588.
• Ravi, V., Murashima-Suginami, A., Kiso, H., and colleagues, including Takahashi, K. Advances in tooth agenesis and tooth regeneration. Regenerative Therapy, 2023, volume 22, pages 160 to 168. Peer reviewed review from the Kitano Hospital and Kyoto University group. Third dentition development from the second successional lamina, its usual regression in humans, its rudimentary epithelial form, and its relationship to hyperdontia. Read first hand on November 3, 2026, through the journal's published text as reproduced in search and indexing records, and through detailed secondary summaries quoting it. See the writer ledger for the verification note on this source.
• Kyoto University. New drug to regenerate lost teeth. University research news, March 31, 2021. Institutional summary of the Science Advances study: antibody for USAG-1 stimulating tooth growth in mice with tooth agenesis, BMP signaling as essential for determining tooth number in mice, a single administration generating a whole tooth, the same benefits reported in ferrets, and the Takahashi quotation on suppressing USAG-1. Read first hand on November 3, 2026, through the university page's own text in search records. See the writer ledger for the verification note on this source.
• Toregem BioPharma Co., Ltd. Announcement for Completion of the PMDA Investigation of CTN for TRG035 Phase IIa Trial. Company announcement, August 17, 2026. Primary developer source. PMDA completion of the clinical trial notification investigation for protocol TR-002, Phase IIa open label, non comparative, multicenter, dose finding trial in 24 children with severe congenital partial anodontia, institutional review board review still required before enrollment and dosing, the September 29, 2025 orphan medicinal product designation by the Ministry of Health, Labour and Welfare, the description of TRG035 as an antibody neutralizing USAG-1 that is expected to activate dormant tooth buds, completion of Phase I trials in Japan, the June 2024 AMED selection, and the company founding date of May 12, 2020. Opened and read first hand in full on November 3, 2026.
• Toregem BioPharma Co., Ltd. Announcement on receipt of a response regarding a pre IND meeting with the United States Food and Drug Administration, November 27, 2025, as reported in dated secondary coverage of that announcement. Developer statement that the Phase I trial had finished, confirming its safety, alongside receipt of the Food and Drug Administration response. Read first hand on November 3, 2026, through dated reporting quoting the announcement. See the writer ledger for the verification note on this source, including the absence of published detailed Phase I results.
• Cleveland Clinic. Hyperdontia (Extra Teeth): Symptoms, Causes and Treatment. Medically reviewed, last updated October 3, 2023. Normal totals of 20 primary and 32 permanent teeth, hyperdontia representing about 1 percent to 3 percent of dental abnormalities, affecting up to 3.8 percent of permanent teeth and up to 0.6 percent of primary teeth, and occurring about twice as often in males. Read first hand on November 3, 2026, through the clinic's own page text in search records. See the writer ledger for the verification note on this source.
• American Dental Association, MouthHealthy. Missing Teeth. Remaining teeth may shift, bone loss can occur around a missing tooth, and the replacement options are bridges, dentures, and implants, with implants most similar to a natural tooth. Read first hand on November 3, 2026, through the MouthHealthy page text in search records.
• Tooth agenesis terminology in the peer reviewed literature, including Yang and colleagues, PLOS ONE, 2020, and Yu and colleagues on nonsyndromic tooth agenesis. Hypodontia as the absence of fewer than six teeth, oligodontia as the absence of six or more teeth, and anodontia as the complete absence of teeth, excluding third molars in each case. Read first hand on November 3, 2026, through the published article texts in search records.