Palatal marginal alveolar exostosis: a narrative review of a scarcely explored condition

Introduction

Exostoses are proliferative bone alterations of still-unknown etiology (1), characterized by the formation of multiple bony spurs or nodules that may occur in different regions of the body, with a predilection for long bones (2,3).

In the oral cavity, these formations correspond to benign bony outgrowths (4). They usually develop on the maxillary and/or mandibular cortical plates and are characterized by slow but progressive growth (1). Upon palpation, exostoses present as solid bony masses. Despite the elevation of the hard tissue, the overlying mucosa usually remains intact and exhibits a normal color (5). Although generally asymptomatic (6), these formations may cause speech and mastication disorders, mucosal trauma and ulceration due to denture use, prosthetic instability, difficulties during intubation, obstructive sleep apnea, cancer phobia, and adverse surgical sequelae in periodontal treatment (7-9).

Among the various exostoses, there is a specific type, located on the palatal surface of the posterior maxilla (2,4), the palatal marginal alveolar exostosis (PMAE). Although narrative reviews addressing oral exostoses as a broad group have been published previously (2,10), none have focused specifically on the PMAE. The scarcity of data regarding PMAE, together with the recent publication of a study demonstrating its high prevalence in a specific population (11), justifies the need to investigate this condition further and to detail its morphology, location, clinical implications, and therapeutic management. Therefore, this narrative review aims to synthesize the available information about these particular and frequently neglected exostoses. We present this article in accordance with the Narrative Review reporting checklist (available at https://fomm.amegroups.com/article/view/10.21037/fomm-25-27/rc).

Methods

A bibliographic search was carried out in the PubMed, Web of Science, and Google Scholar databases, including academic studies published in English or eligible for translation into English. The search strategy included the Medical Subject Headings (MeSH) terms “Exostosis”, “Hyperostosis”, “Anatomic Variation”, and “Maxilla”. Additional terms commonly used in studies, such as “bony exostosis”, “buccal exostoses”, and “oral mucosal alterations”, were also applied.

Duplicate articles, opinion papers, commentaries, and book reviews were excluded. No restrictions were applied regarding the year of publication. The included articles were published from 1972 up to the search date (12 September 2025) (Table 1).

Literature review and discussion

Definition and diagnostic challenges

PMAE, also referred to as palatal exostoses or palatal tubercles, are bony protuberances that develop on the palatal surface of the maxillary alveolar processes (8,12-14). In general, they are asymptomatic (6) and may go undetected in clinical examinations or routine radiographs (11,15,16), remaining a little-known condition among professionals.

The presence of PMAE has been associated with sex, age, and laterality, although available findings are heterogeneous. Regarding sex, some studies found higher prevalence in males (12,14), while others reported predominance in females (11). A higher occurrence was observed in adults aged 30–59 years, with progressive reduction thereafter (11,12), suggesting a possible age-related pattern, although this still lacks robust statistical validation. Laterality has also been discussed, with bilateral PMAEs being the most frequently reported presentation (11,12,15). Additionally, no relationship was found between the presence of palatine tori and PMAE among the patients (11). These findings highlight the need for studies with rigorous methodological designs and larger population samples, since existing studies remain limited in exploring these associations.

PMAEs are often underdiagnosed due to a combination of their location, small size and the thick gingival mucosa overlying the posterior maxilla (2,8,11). The thickness of this mucosa often equals or exceeds that of the underlying bone, with a proportion close to 1:1, which complicates clinical identification, especially for smaller formations (15,16).

This anatomical configuration reduces their detectability during clinical inspection, palpation, and conventional radiographic examinations. Consequently, although PMAEs appear highly prevalent in cone-beam computed tomography (CBCT) analyses and anatomical studies using dry skulls, they remain largely overlooked in routine dental practice (8,16). A CBCT analysis reported a prevalence of PMAE of 54.80%, with a predominance of small nodules (62.42%) located in the molar region (11). An evaluation conducted during periodontal surgical procedures indicated an even higher prevalence of 77.97% (8). In contrast, a study relying exclusively on clinical examination reported a considerably lower prevalence of 14.1% (16). Anatomical studies of dry human skulls observed PMAE prevalence of 30% (15), 40.53% (17), and 56% (12).

The convergence of findings from CBCT and anatomical studies using dry skulls supports the hypothesis that PMAE may be more prevalent than routinely recognized in dental practice (11,12). Thus, CBCT is an essential tool in the diagnosis of PMAE, as it enables three-dimensional evaluation of the maxilla, allowing precise identification of its morphology, location, and bone pattern (11,18). Furthermore, CBCT can be used to estimate bone density (19) and assess the growth pattern of these exostoses (18).

Etiology

The etiology of PMAEs remains unclear. Proposed mechanisms include reactive bone formation following periosteal trauma (20), particularly after free gingival graft or connective tissue graft procedures (21), and activation of osteoprogenitor cells and bone morphogenetic proteins, culminating in exostosis formation (20). However, these isolated triggers may be insufficient on their own, and genetic predisposition has also been suggested to play a role (13). Current evidence is limited, highlighting the need for studies that integrate clinical, radiographic, functional, and demographic variables to clarify the biological basis of PMAE development and progression.

Morphology, classification and histology

Morphological descriptions of PMAEs vary, but small nodules are the most frequently reported presentation across CBCT and anatomical studies (11,15,17). Larato’s classic classification remains the most widely adopted and categorizes PMAEs into five morphological types: (I) small nodules: multiple small dimension bony nodules; (II) large nodule: a single circumscribed bony eminence; (III) sharp ridge: elongated linear projections extending mesiodistally; (IV) spine-like projections: single or multiple spiny prominences on the palatal bone; (V) combinations: nodules, ridges, and spines may coexist within the same structure (15) (Figure 1).

Figure 1 Schematic representation of the classification of palatal marginal alveolar exostoses according to Larato (14): (A) small nodules; (B) large nodule; (C) sharp ridge; (D) spine-like projections; (E) combinations of the previous types.

According to the PMAE’s anatomical distribution, they have been classified as exostoses located in the maxillary tuberosity, in the molar region, in the premolar region, or without a defined location (Figure 2). In patients with primary or mixed dentition, the premolar region corresponds to the area of deciduous molars. Exostoses without a defined location are those found in edentulous areas where precise determination of the corresponding dental region is not possible (4,22).

Figure 2 Schematic representation of the classification of palatal marginal alveolar exostoses according to their location.

Histologically, PMAEs exhibit mature hyperplastic bone composed of cortical and trabecular components (2,5). A recent research reported a mixed composition, with predominance of cortical bone but a significant amount of trabecular bone (11), in contrast with previous studies, which described minimal trabecular bone in exostoses (23,24). These findings have important implications for their regenerative potential. Trabecular bone is known for its osteogenic potential (25), suggesting that PMAEs might serve as viable autogenous donor sites for bone grafting. This hypothesis should be interpreted with caution until comparative clinical studies confirm volume availability, osteogenic properties, and regenerative performance relative to established PMAE as donor sites.

Clinical management

Most PMAEs are asymptomatic and do not require intervention. Conservative monitoring is recommended when no functional disturbances are present. Surgical removal is reserved for cases involving persistent pain or discomfort, chronic mucosal trauma, interference with prosthetic stability or adaptation, difficulties in periodontal surgical closure, or when the exostosis presents rapid growth or causes functional limitations (2,6).

Surgical management may be challenging due to the limited mobility of the palatal mucosa (12) and the anatomical location of the PMAE (11). Minimally invasive techniques are preferred to reduce the risk of periosteal damage and potential gingival hyperplasia (22) and to reduce the risk of injury to the greater palatine neurovascular bundle due to its anatomical proximity (2). When properly executed, surgery shows favorable outcomes and a low recurrence rate (23). Failure to remove PMAEs has been associated with delayed healing and difficulties in achieving ideal flap positioning in periodontal surgeries (8).

Despite these clinical insights, objective criteria defining when to observe and when to intervene remain absent from the literature. Studies addressing the longitudinal behavior of PMAEs are necessary for hampering efforts to establish evidence-based clinical guidelines.

Integrative considerations and future directions

The existing literature demonstrates considerable heterogeneity in diagnostic methods, morphological descriptions, and epidemiological findings, underscoring the need for methodologically robust studies. Standardized diagnostic criteria, incorporating clinical, imaging, and anatomical parameters, are essential to reduce variability across studies and prevent confusion with other types of exostoses.

Longitudinal investigations are also necessary to clarify the biological behavior and progression of PMAEs over time, as well as the influence of demographic, functional, genetic, and environmental factors.

From a clinical standpoint, structured guidelines are needed to define observation versus intervention thresholds and to establish surgical protocols tailored to PMAE morphology and location. Although their trabecular component suggests potential utility as an autogenous bone-graft donor site, this possibility remains speculative until validated by controlled comparative studies.

Overall, coordinated, protocol-driven research is crucial to advance both the biological understanding and possible clinical application of PMAEs.

Strengths and limitations

This narrative review contributes by consolidating and organizing the current knowledge on PMAEs, a condition that is academically underexplored and often overseen in clinical practice. It aims to expand the clinical discussion on their relevance and guide future research. Among the limitations of this study is its design; as a narrative review, it is less methodologically demanding than a systematic review, since it does not require a comprehensive literature search. This may introduce interpretation bias and compromise the reproducibility of findings (26). The available literature on PMAEs is scarce, heterogeneous, and largely composed of studies with small samples, distinct methodologies, and a lack of standardized diagnostic criteria (8,11,12,15-17), which hinders consistent conclusions about their prevalence, morphology, and clinical implications. Finally, the idiomatic restriction to publications may have introduced a language bias, limiting the inclusion of relevant studies in other languages.

Conclusions

PMAE is a frequent and benign anatomical variation that is often overseen by professionals, despite its potential to interfere with clinical procedures. Its identification requires the use of three-dimensional imaging examinations. The most common presentation consists of small, bilateral nodules in the molar region. There is a clear need for robust studies to further investigate its etiology, progression, and to confirm its potential as a donor site for bone grafting in oral surgeries.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the Narrative Review reporting checklist. Available at https://fomm.amegroups.com/article/view/10.21037/fomm-25-27/rc

Peer Review File: Available at https://fomm.amegroups.com/article/view/10.21037/fomm-25-27/prf

Funding: This study was supported by the Coordination for the Improvement of Higher Education Personnel (CAPES) (No. 88887.946978/2024-00 to L.d.S.L.).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://fomm.amegroups.com/article/view/10.21037/fomm-25-27/coif). L.E.R.V. serves as an unpaid editorial board member of Frontiers of Oral and Maxillofacial Medicine from October 2025 to September 2027. L.d.S.L. is a scholarship holder of the Coordination for the Improvement of Higher Education Personnel (CAPES) (No. 88887.946978/2024-00). The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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