Mandibular tori (MT) are common, slow-growing, benign bony growths that form on the inside (lingual) surface of the lower jaw (mandible). These protuberances are generally non-pathological, meaning they are not considered a disease state and are not cancerous. They consist of dense cortical bone covered by normal oral mucosa, usually appearing near the premolar and canine teeth. MT often develop gradually over time, though they can be present from birth, and typically do not cause significant issues.
Prevalence
Mandibular tori are relatively common, but their reported frequency varies widely across different studies and populations, with prevalence estimates generally ranging from 5% to over 40% of the adult population. A narrower, frequently cited range for the general population is between 7% and 10%. This variation depends heavily on the specific population studied, the diagnostic criteria used, and the ethnic background of the subjects.
The bony growths are most often bilateral, meaning they appear on both the left and right sides of the lower jaw, occurring in approximately 80% to 90% of cases. They usually begin to appear or become noticeable after puberty, with the average age of onset often cited in the fourth decade of life. The size of the tori can vary significantly, from a small nodule to a large, lobulated mass, but the majority remain relatively small.
Demographic data suggests a higher prevalence in males compared to females; for instance, one study reported a 38% prevalence in males versus 23% in females. Prevalence also differs based on ethnicity, with lower rates observed in Caucasian and Black populations compared to higher rates reported in certain Asian and Inuit populations.
Causes and Risk Factors
The formation of mandibular tori is multifactorial, stemming from a combination of genetic predisposition and local environmental factors. Genetics plays a significant role, as the condition is often heritable and believed to be passed down through families, possibly as an autosomal dominant trait. The presence of MT in identical twins further supports a strong underlying genetic component in their development.
Mechanical stress factors are the major stimuli that cause bone growth in susceptible individuals. The most significant is chronic occlusal stress, which is the excessive force placed upon the jawbone during chewing or clenching. Bruxism, the involuntary grinding or clenching of teeth, is a well-established risk factor because this constant mechanical loading stimulates bone remodeling and growth.
The tori almost always form in the area of the premolar and canine teeth, which are the regions of the mandible that bear the greatest mechanical stress from biting and chewing. Other factors that may contribute include nutritional elements, such as high calcium intake, and certain vitamin deficiencies. However, the primary mechanism is the body’s response to functional stress in a genetically predisposed individual.
Clinical Implications and Management
Mandibular tori are usually asymptomatic and require no intervention, as they are non-pathological and do not affect daily life. Most individuals are unaware of their presence until they are discovered incidentally during a routine dental examination. Their slow growth often stops spontaneously, and they rarely cause pain or discomfort.
The growths become clinically significant when they interfere with other oral functions or treatments, which is the main reason for considering removal. The most common indication for surgical removal is when the tori prevent the proper fitting, stability, or comfort of removable dental prostheses, such as dentures.
Other reasons for intervention include persistent trauma or ulceration of the thin tissue covering the bony lumps, often caused by sharp foods or accidental biting. In rare instances, very large tori can interfere with tongue movement, leading to speech difficulties or problems with oral hygiene.
When removal is indicated, the procedure involves surgical excision, which is typically a straightforward outpatient procedure performed under local anesthesia to reduce the size of the bony protuberance.