Torus palatinus

Torus palatinus is a benign, non-neoplastic bony exostosis arising along the midpalatal suture of the hard palate.[1][2] It represents a developmental anatomic variation rather than a true neoplasm, composed of hyperplastic cortical and trabecular bone.[1][3] The etiology is multifactorial, involving an interplay of genetic predisposition—thought to follow autosomal dominant inheritance with variable penetrance—and environmental or functional factors such as occlusal (masticatory) forces.[2][4] On imaging, torus palatinus appears as a well-defined, midline palatal radiopacity continuous with the palatal bone. Most cases are asymptomatic and discovered incidentally; surgical removal is reserved for functional or prosthetic indications.[5][6]

• Torus palatinus is the accepted term in current clinical and anatomical usage.[1][2]
• The abbreviation TP is widely used in the literature.
• Torus palatinus is classified among the oral tori and exostoses, a group that also includes torus mandibularis and buccal/palatal exostoses. It is distinguished from palatal exostoses, which arise from the alveolar process of the maxilla rather than the midpalatal suture.[2][7]
• The term "torus maxillaris" has been applied inconsistently in some literature to buccal or palatal alveolar exostoses and should not be confused with torus palatinus.[2]
• Despite the Latin root suggesting a tumor, torus palatinus is universally recognized as a non-neoplastic developmental anomaly.[6]

Torus palatinus is the most common oral exostosis.[2] Reported prevalence varies widely across populations, ranging from approximately 4% to over 60%, reflecting genuine ethnic variation and differences in study methodology.[1][7]

• Sex: Most studies report a female predominance, with females affected roughly twice as often as males. Autosomal dominant inheritance linked to the X chromosome has been proposed to explain this pattern.[1][2][7]
• Age: Growth typically begins around puberty and becomes clinically apparent in the third to fourth decade, with prevalence peaking in middle age (35–65 years). Tori may continue to enlarge slowly throughout adulthood.[5][7][8]
• Ethnicity: Higher prevalence has been reported in Asian, Inuit/Arctic, and Northern European populations; lower rates are generally observed in African-descent populations, though considerable overlap exists.[7]
• Co-occurrence: Torus palatinus and torus mandibularis may coexist in the same individual, supporting a shared genetic basis.[4][9]

Presentation

Torus palatinus presents as a painless, firm, sessile bony mass on the midline of the hard palate, covered by thin, poorly vascularized mucosa.[1][7] Most cases are discovered incidentally during routine oral examination or dental radiography.[1][10]

Morphology

Four morphological types are recognized based on surface contour:[1][8]

• Flat — broad, slightly elevated plateau; the most common form in many series
• Spindle — elongated fusiform ridge along the midpalatal suture
• Nodular — single or few rounded protuberances
• Lobular — multiple lobulated masses, often the largest variant

Size ranges from a few millimeters to several centimeters; most are smaller than 2 cm.[1][9] Tori are characteristically symmetrical about the midline and most commonly centered in the premolar region.[1][9]

Symptoms and complications

• Tori are typically asymptomatic.[1][5]
• Large tori may interfere with speech, swallowing, or mastication.[6]
• The thin overlying mucosa is susceptible to traumatic ulceration from hard foods or ill-fitting prostheses.[5][6]
• Prosthetic rehabilitation (particularly complete dentures) may be complicated by the presence of a prominent torus.[4][5]

Tempo

Growth is slow and continuous; spontaneous cessation of growth has been observed following tooth loss.[7] Rapid enlargement is not a feature of torus palatinus and should prompt further investigation.

Location and distribution

Torus palatinus arises from the midpalatal suture and is centered on the midline of the hard palate.[1][9] On panoramic radiography, it projects as a radiopaque mass superimposed over the maxillary apical region, most commonly at the level of the premolars.[1][9] Because the torus is a palatal structure, it is projected above the apices of the maxillary teeth on panoramic images, where it may be mistaken for a pathologic entity if the clinician is unfamiliar with this normal variant.[11] On maxillary occlusal radiographs, the torus is seen as a well-defined midline radiopacity overlying the palatal suture.

Periphery and shape

• The periphery is characteristically well-defined and smooth, with a corticated border that blends imperceptibly into the adjacent palatal bone.[6][12]
• Shape on cross-sectional imaging mirrors the clinical morphology: flat tori appear as a broad, low-profile convexity; spindle forms as an elongated midline ridge; nodular and lobular variants as rounded or multilobulated protuberances projecting inferiorly from the palatal vault.[6][9]
• No perilesional radiolucent rim or capsule is present; the lesion is in direct continuity with the palatal bone.

Internal architecture

• The internal structure is a mixture of dense cortical bone and variable amounts of trabecular (cancellous) bone, producing a uniformly radiopaque to mildly heterogeneous appearance.[1][3]
• Small tori tend to be predominantly cortical and therefore uniformly dense, while larger lobular tori may contain a more conspicuous trabecular component with a visible marrow space.[3]
• No internal calcifications, septations, or soft-tissue density components are present.

Effects on teeth and adjacent structures

• Torus palatinus characteristically does not displace, resorb, or otherwise affect the roots of adjacent teeth.[6]
• The periodontal ligament space and lamina dura of the maxillary teeth remain intact.
• The nasal floor and maxillary sinuses are unaffected.
• On panoramic radiographs, superimposition of the torus over the maxillary apices may obscure periapical pathology, necessitating supplemental periapical or cross-sectional imaging for complete evaluation.[11][13]

Extent and cortical involvement

• The torus is an exophytic outgrowth of the palatal cortex; it expands the palatal surface inferiorly without eroding or destroying cortical bone.[3][6]
• Cross-sectional imaging demonstrates continuity of the torus cortex with the palatal cortical plate, confirming its origin from the midpalatal suture region.
• Large tori may substantially reduce the oral cavity volume and narrow the space between the palatal vault and the tongue.

Variants

• Multilobulated torus: Multiple lobules may give a "cauliflower" appearance on cross-sectional imaging; this is a morphological variant, not a sign of aggressive behavior.
• Asymmetric torus: Occasional mild asymmetry is reported, though the vast majority are symmetrical about the midline.[4][9]
• Giant torus: Rarely, tori exceed 5 cm and may require surgical planning with guided techniques.[14]

CT findings

Medical CT or CBCT may be obtained when the clinical or panoramic appearance is atypical, when surgical excision is planned, or when the torus obscures evaluation of adjacent structures. Cross-sectional imaging demonstrates a well-defined, homogeneously dense bony mass arising from the midpalatal suture, in direct cortical continuity with the palatal bone, without soft-tissue component, periosteal reaction, or bone destruction.[6] Axial and coronal reformats allow precise measurement of torus dimensions and assessment of the relationship to the nasal cavity floor and nasopalatine canal, which is valuable for preoperative planning.[6][14]

MRI

MRI is not routinely indicated. When performed for other reasons, torus palatinus appears as a signal-void structure on all pulse sequences, consistent with dense cortical bone, and is readily distinguished from soft-tissue palatal masses such as salivary gland tumors.[15][16]

The midline palatal location, cortical continuity with the palatal bone, and absence of aggressive features make torus palatinus a straightforward diagnosis in most cases. The differential is relevant when the lesion is atypical in location, asymmetric, rapidly enlarging, or associated with mucosal ulceration or bone destruction.

The highest-risk diagnostic pitfall is misidentifying a palatal osteoma—particularly in the setting of multiple osteomas suggesting Gardner syndrome—as a benign torus. When a palatal bony mass is solitary but off-midline, asymmetric, or demonstrates progressive enlargement, further imaging and clinical correlation (including evaluation for supernumerary teeth, intestinal polyposis, and APC gene mutation) are warranted.[17][18][20]

Histological examination of torus palatinus is rarely performed because the diagnosis is clinical and radiographic. When excised, the specimen consists of mature lamellar (Haversian) bone with a cortical shell and variable amounts of internal trabecular bone.[1][3]

Microscopic features

• The cortex is composed of dense lamellar bone with well-organized Haversian systems.[3]
• Trabecular bone, when present, contains normal fatty or hematopoietic marrow.
• No atypia, increased mitotic activity, or cartilaginous component is present.

Asymmetric remodeling

A distinctive histomorphometric feature has been described: within the Haversian canals, osteoid deposition (osteoblastic activity) occurs preferentially on the side facing the free torus surface, while osteoclastic resorption (Howship's lacunae) predominates on the opposite side.[3] This asymmetric bone remodeling pattern may represent a histological feature that distinguishes tori from other exostoses.[3]

Radiologic-pathologic correlation

The uniformly dense radiographic appearance corresponds to the predominance of compact lamellar bone. Larger, lobular tori with a more heterogeneous radiographic pattern correlate with a greater proportion of internal trabecular bone and marrow spaces.[3]

Indications for intervention

Most tori require no treatment. Accepted indications for surgical removal include:[5][6]

• Interference with prosthetic rehabilitation (denture fabrication or fit)
• Recurrent traumatic ulceration of the overlying mucosa
• Impairment of speech or swallowing (large tori)
• Patient anxiety regarding the mass ("cancer phobia")
• Harvesting autogenous bone graft material for alveolar ridge augmentation or implant site preparation[21]

Surgical technique

• Excision is performed under local or general anesthesia via a midline palatal mucoperiosteal flap.[14][22]
• Bone removal is accomplished with rotary instruments (surgical bur), osteotomes, or piezoelectric devices; Er:YAG laser has been described as an alternative.[22]
• Surgical guides have been used for large or unusually shaped tori to reduce the risk of undercorrection and improve postoperative contour.[14]

Complications

• The thin, poorly vascularized palatal mucosa is prone to wound dehiscence and delayed healing.
• Hemorrhage, infection, and palatal numbness are uncommon but recognized risks.[14][22]

Bone graft potential

Torus palatinus bone has been successfully used as particulate or block autograft for alveolar ridge reconstruction.