How Common Is Mandibular Tori and What Causes It?

Mandibular tori show up in roughly 5 to 40 percent of people worldwide, depending on the population studied and the method used to detect them. These bony bumps along the inner surface of the lower jaw are among the most common non-cancerous oral growths, yet most people who have them never realize it until a dentist points them out during a routine exam. The wide range in reported prevalence reflects real differences across ethnic groups, age brackets, and geographic regions, and the causes turn out to be a tangle of genetics, jaw mechanics, and possibly even diet.

What Mandibular Tori Actually Are

Mandibular tori are slow-growing, bony outgrowths that appear on the tongue side of the lower jaw. They belong to a family of oral bone growths that also includes torus palatinus (a bump on the roof of the mouth) and torus maxillaris (on the cheek side of the upper jaw).¹ They typically sit in the premolar region, roughly below the small teeth between the canines and molars, and most often appear on both sides of the jaw. A CT-based study found the average cortical thickness of these growths was about 7 mm, and all the tori examined were composed entirely of cortical (hard, outer-layer) bone.²

In terms of shape, mandibular tori can be single rounded nodules, multiple small bumps strung together like a chain, or broad flat ridges. The bilateral solitary form, a single bump on each side, tends to be the most common shape.³ They are covered by the same thin mucosa that lines the floor of the mouth, which is why they can feel hard and bony to the touch if you run your tongue along the inside of your lower jaw. Most are small enough that you would never notice them without looking, but in rare cases they grow large enough to crowd the tongue or interfere with speech.

How Common They Are Across Different Groups

Prevalence figures for mandibular tori vary enormously from study to study, and much of that variation is real rather than methodological noise. Populations in East Asia and the Arctic have historically shown higher rates. A study of modern Korean skeletal remains found mandibular tori in about 55 percent of individuals, which is at the high end of what has been reported globally.⁴ By contrast, a study of edentulous patients in Saudi Arabia found a prevalence of about 10 percent.³

A U.S.-based study examining women from multiple ethnic backgrounds found tori (both palatal and mandibular combined) in about 30 to 39 percent of participants, with no statistically significant difference between African American, Caucasian, Hispanic, and Asian groups.⁵ That finding is a useful corrective to the older assumption that tori are dramatically more common in some ethnic groups than others. The differences exist but are often more modest than textbooks once suggested, and detection method matters a lot: CT scans pick up small tori that a visual exam would miss entirely.

Most studies find no meaningful sex difference in mandibular tori prevalence, though some earlier work reported slightly higher rates in men. The Saudi study, for example, found that males and females had similar rates.³ Mandibular tori tend to become more noticeable through adulthood, with many appearing or growing during the 30s and 40s, then potentially stabilizing or even shrinking in later decades as overall bone density declines.

The Genetic Factor

Genetics plays a substantial role in who develops mandibular tori. A twin study found very high concordance among identical twins and moderate concordance among fraternal twins, yielding a heritability estimate of about 66 percent.⁶ In plain terms, roughly two-thirds of the variation in whether people develop these growths can be attributed to inherited factors. That is a strong genetic influence, but it also leaves a significant chunk of the picture unexplained by genes alone.

The prevailing view among researchers is that mandibular tori are a “threshold trait,” meaning a person needs both a genetic predisposition and some environmental trigger to push bone growth past the point where a torus becomes visible. This threshold model helps explain why prevalence varies so much between populations that share similar genetic backgrounds but differ in diet or jaw-loading habits.⁷ If you have a strong genetic predisposition, it may take only modest mechanical stress to trigger a torus. Without that predisposition, even heavy jaw stress might never produce one.

Mechanical Stress and Bruxism

The most widely discussed non-genetic cause is mechanical loading on the jaw, particularly bruxism (grinding or clenching the teeth). The logic is straightforward: bone responds to stress by remodeling, and the inner surface of the mandible where tori grow is a region that absorbs significant bite force. A systematic review of the evidence found that abnormal tooth wear, a proxy for chronic grinding, was associated with higher odds of having mandibular tori.⁸ However, self-reported teeth grinding and clenching showed contradictory results across studies, and the overall quality of evidence was rated low to very low.

The honest assessment is that the bruxism-tori connection is plausible and probably real to some degree, but it has been difficult to prove convincingly. One problem is that bruxism itself is hard to measure reliably, since most grinding happens during sleep and people underreport it. Another is that cross-sectional studies can show that two things occur together without proving one caused the other. Someone who grinds their teeth and has mandibular tori might have both because of the same underlying genetic tendency toward dense bone and strong jaw muscles, rather than one causing the other.

Diet and Environmental Influences

Some researchers have pointed to diet as a contributing factor, particularly consumption of saltwater fish. These fish are rich in polyunsaturated fatty acids and vitamin D, both of which play roles in calcium and phosphate regulation and therefore in bone development. Excessive consumption of calcium-rich products has also been implicated.⁹ This dietary hypothesis has been used to help explain why populations in coastal and Arctic regions, where fish consumption is traditionally very high, tend to have elevated tori prevalence.

The dietary connection remains circumstantial, though. It is hard to separate the effect of eating fish from the genetic makeup of the populations that traditionally eat a lot of fish. Still, the fact that modern Koreans show a much higher tori prevalence than their historical counterparts from the same region (roughly 55 percent versus 13 percent) despite relatively stable dietary patterns suggests that something beyond simple food intake is at work.⁴ Changes in overall nutrition, longevity, and perhaps the stresses of modern life on jaw muscles may all contribute.

Do Tori Signal Stronger Bones Elsewhere?

One of the more intriguing findings about mandibular tori is their association with bone mineral density at sites far from the jaw. A study of community-dwelling elderly men and women found that people with mandibular tori had significantly higher bone mineral density at the lumbar spine, femoral neck, and hip compared to those without tori.¹⁰ The association was particularly clear in women who were not on hormone replacement therapy. The researchers suggested that having tori early in life could be a marker of higher bone density later and potentially a lower risk of developing osteoporosis.

A separate study of elderly women reinforced this pattern, finding that those with mandibular tori had significantly higher femoral bone density than those without.¹¹ The implication is that some shared biological mechanism, likely involving how the body regulates bone formation and resorption, drives both torus development and overall skeletal robustness. This does not mean that mandibular tori are protective in themselves; rather, they may be a visible sign of the kind of bone metabolism that happens to produce denser bones throughout the skeleton.

Mandibular tori have also been associated with tooth retention. A CT-based study found that in all age groups over 30, patients with mandibular tori had a lower rate of tooth loss and maintained more functional biting contacts than patients without them.¹² Whether the tori themselves help preserve teeth or whether the same robust bone that produces tori also better anchors teeth is an open question, but either way, having mandibular tori is not a bad sign for your dental future.

When Mandibular Tori Cause Problems

Most mandibular tori are completely harmless and never need treatment. They grow slowly, they are not cancerous, and they rarely cause pain. But they can become a practical problem in a few specific situations.

The most common clinical headache is denture fitting. The thin mucosa covering mandibular tori does not cushion well against the pressure of a denture base, and large tori can physically prevent an impression tray or denture from seating properly.¹³ For patients who need complete lower dentures, tori can turn what is already a difficult prosthetic challenge into a genuinely frustrating one. Workarounds include special impression techniques, soft linings inside the denture base, and careful management of patient expectations about comfort.¹⁴

In rare cases, tori grow large enough to interfere with tongue movement and speech. A case report documented a patient whose massive palatal and mandibular tori restricted the tongue’s ability to move upward and backward, distorting articulation. Surgical removal restored normal tongue movement and improved pronunciation.¹⁵ These extreme cases are uncommon, but they illustrate that there is a size threshold beyond which tori stop being harmless curiosities.

Tori can also be annoying for more mundane reasons. The thin tissue covering them is prone to ulceration from hard or sharp foods like chips and crusty bread. People with prominent tori sometimes notice that food gets trapped behind them. And the growths can occasionally alarm someone who discovers an unfamiliar hard lump in their mouth and fears the worst, though any dentist can identify a torus on sight.

Surgical Removal and Bone Grafting

When tori do need to come out, the surgery is generally straightforward. It is done under local anesthesia, involves reflecting the gum tissue, chiseling or drilling the bony growth from the mandible, and closing the tissue back over the smoothed surface. Recovery typically takes a couple of weeks, with some swelling and discomfort around the floor of the mouth. Most people return to normal eating within a few days.

One genuinely useful twist is that removed tori can serve as a free source of bone graft material. Because tori are dense cortical bone with a mineral composition dominated by hydroxyapatite, the same primary mineral in all human bone, they are excellent autogenous graft material.¹⁶ Surgeons have used torus bone chips to fill periodontal defects, augment the jawbone before dental implant placement, and even build up the floor of the maxillary sinus for implant support.¹⁷

Autogenous bone, meaning bone harvested from the patient’s own body, is considered the gold standard for grafting because it carries living cells and growth factors that synthetic or cadaver-derived materials lack. The typical donor sites for jaw-area grafts, such as the chin or the back of the jaw near the wisdom teeth, require creating a surgical wound in healthy tissue. If tori are already present and already need removal (or are simply surplus bone the patient does not need), harvesting them avoids that extra surgical site entirely.¹⁸ Studies have shown good bone fill and pocket reduction when torus bone chips are used to treat periodontal bone defects, with results maintained at 6- and 12-month follow-ups.¹⁹ Combining the bone chips with platelet-rich plasma gel showed even better clinical outcomes for periodontal therapy.²⁰

One thing to be aware of is that tori can recur after removal. If the underlying mechanical or genetic drive for bone growth is still present, the torus may slowly re-form over months or years. A case report documented early recurrence following surgical resection, which underscores that removing the growth does not address whatever caused it in the first place.⁹

Having Both Palatal and Mandibular Tori

Some people develop bony growths on both the roof of the mouth and the inner jaw. An older large-scale dental study found that about 3 percent of patients had both torus palatinus and torus mandibularis simultaneously.²¹ A Norwegian population study noted that while the overall correlation between having both types was not statistically significant, each type of torus appeared more than twice as often in someone who already had the other type.²² That pattern is consistent with a shared underlying predisposition to bony overgrowth in the oral cavity, even if the two conditions are not tightly linked on a one-to-one basis. If your dentist has pointed out a bump on the roof of your mouth, it is worth checking the inner jaw as well, and vice versa.

What Anthropologists Learn From Tori in Ancient Skeletons

Mandibular tori have been a topic of interest in anthropology for over a century because they leave clear marks on skeletal remains. Researchers studying past populations have used tori frequencies as one of many “non-metric traits,” physical features that vary between populations and can help gauge biological relationships between groups. The picture that has emerged from archeological work is consistent with the threshold model: tori frequencies vary significantly not only between populations (suggesting genetic influence) but also between different levels of dental wear within the same population (suggesting mechanical stress plays a role too).⁷

The geographic and temporal distribution of mandibular tori across fossil hominids, archaeological skeletons, and modern populations is strikingly uneven.²³ Arctic and sub-Arctic populations, both ancient and modern, tend to have some of the highest rates recorded. One long-standing explanation involves the heavy mechanical loading these populations put on their jaws, historically using teeth as tools for processing hides and other materials. But the genetic component is hard to separate from the lifestyle component, since these populations are also genetically distinct from equatorial groups. This dual entanglement of genes and environment is part of what makes tori frequencies less reliable as a pure marker of biological distance between populations than researchers once hoped.

Tori and Modern Dental Imaging

Mandibular tori are easily visible on panoramic dental X-rays as opaque (white) projections overlapping the roots of the premolar teeth. CT imaging provides more detail, revealing that the thickest part of a torus typically sits just below the alveolar ridge (the bony ridge that holds the teeth), particularly in the zone between the canine and the second premolar. Cortical thickness tapers off sharply as you move downward along the jaw.²⁴ This anatomical detail matters for surgical planning: knowing exactly where the bone is thickest helps a surgeon decide how much to remove and how to approach the cut, especially when the goal is to harvest graft material of a specific volume.

The increasing use of cone-beam CT in routine dental practice means more tori are being detected incidentally, including small ones that would never have been noticed on a standard exam or a two-dimensional X-ray. This may partly explain why some recent prevalence studies report higher numbers than older ones. The growths were always there; the imaging just got better at catching them. For patients, an incidental torus finding on a scan should not be a source of worry. Unless the growth is causing a specific functional problem, the standard recommendation is to leave it alone and simply monitor it over time.

1
PubMed. Asymmetric bone remodeling in mandibular and maxillary tori
2
PubMed. Prevalence and anatomic topography of mandibular tori: computed tomographic analysis
3
PubMed Central. Prevalence and pattern of torus palatinus and torus mandibularis among edentulous patients of Saudi Arabia
4
Anthropological Science. Torus mandibularis in skeletal remains from the Joseon Dynasty and modern Korea
5
PubMed. Occurrence of torus palatinus and mandibularis among women of different ethnic groups
6
PubMed. Oral bony outgrowths: prevalence and genetic factor influence. Study of twins
7
Dental Anthropology. Torus mandibularis in bioarcheological investigation
8
PubMed. Association between signs and symptoms of bruxism and presence of tori: a systematic review
9
International Journal of Surgery Case Reports. Early recurrence of mandibular torus following surgical resection: A case report
10
PubMed. Mandibular and palatal tori, bone mineral density, and salivary cortisol in community-dwelling elderly men and women
11
PubMed. Elderly women with oral exostoses had higher bone mineral density
12
PubMed Central. Computed Tomographic Analysis of Mandibular Tori and Their Relationship to Remaining Teeth
13
PubMed. Complete denture covering mandibular tori using three base materials: a case report
14
PubMed. The ‘anatomically difficult’ denture case
15
PubMed Central. Three-dimensional evaluation of a giant torus in the maxilla and mandible that affected pronunciation: a case report
16
The Open Dentistry Journal. Physicochemical Properties of Torus Mandibularis and Palatinus Indicate a Source of Autogenous Bone Graft
17
PubMed Central. Mandibular Torus Harvesting for Sinus Augmentation: Two-Year Follow-Up
18
PubMed Central. Surgical removal of mandibular tori and its use as an autogenous graft
19
PubMed Central. Mandibular Tori: A source of autogenous bone graft
20
PubMed. Torus mandibularis bone chips combined with platelet rich plasma gel for treatment of intrabony osseous defects: clinical and radiographic evaluation
21
Oral Surgery, Oral Medicine, Oral Pathology. The occurrence of torus palatinus and torus mandibularis in 2,478 dental patients
22
PubMed. Palatine and mandibular tori. A morphologic study in the current Norwegian population
23
Quaternary International. Frequency of mandibular tori in prehistoric and historic Japanese island populations
24
Oral Radiology. Imaging-based anatomical study of torus mandibularis: morphological features identified by computed tomography and their correlation with panoramic radiographic appearances