Fig. 1

Type 1 marginal mandibulectomy. Type 1a: anterior marginal mandibulectomy. The dashed lines depict the proposed bone resection in the anterior portion of the mandible, sparing the inferior border. The left image shows the occlusal view and the right image shows the lateral view of the mandible. Type 1b: marginal mandibulectomy on the lateral aspect (without removal of the coronoid process). The left image provides an axial cross-sectional view, depicting the lesion location and the extent of resection, while the right image shows a lateral view of the mandible with the planned marginal resection. Type 1c: marginal mandibulectomy on the lateral aspect (with the removal of the coronoid process). The left image is an axial cross-sectional view showing the lesion and the planned resection area, while the right image presents a lateral view of the mandible, highlighting the resection of the alveolar ridge and the coronoid process

Fig. 2

Marginal mandibulectomy (oblique, vertical, reverse)

MMs are traditionally classified based on the location or plane of resection. Accordingly, it can be Anterior MM or Posterior MM based on the location anterior or posterior to the canine, respectively. However, we observe inconsistencies among authors in describing the precise locations of the MMs. Similarly, as per the plane of resection, MMs can be horizontal, vertical, or oblique (Shaha). Considering the commonly performed marginal mandibulectomies, we propose a uniform classification for describing different types of mandibulectomies. It is as follows:

Type I: Horizontal marginal mandibulectomy.

Here, the mandibular rim is resected horizontally posterior to the molar to the coronoid process, and the coronoid process may or may not be removed. However, the continuity of the mandible is maintained, and a minimum height of 1 cm is kept at the residual mandible for its strength. This type of mandibulectomy is performed for small primary lesion located in the posterior locations like retromolar trigone. Can be further subdivided into three groups.

Type Ia: Anterior marginal mandibulectomy (any segment anterior to the first molar)

Type Ib: Coronoid sparing posterior marginal mandibulectomy (posterior to the 2nd premolar)

Type Ic: Posterior marginal mandibulectomy with coronoidectomy

Type II: Oblique marginal mandibulectomy.

Type III: Vertical marginal mandibulcetomy on lingual side.

This type involves a vertical resection of the lingual plate of the mandible, focusing on the internal aspect of the mandible. Performed for same indications above but when suspecting a deeper tumour. However, not routinely performed as it is technically challenging and can negatively affect the strength of the residual mandible.

Type IV: Reverse marginal mandibulectomy.

Indications for Marginal Mandibulectomy

Based on the above classification, we shall review the role of marginal mandibulectomy for surgical management of oral cancers in different subsites.

Cancers of the Retromolar Trigone (RMT)

The retromolar trigone is a small, triangular area in the oral cavity located just behind the last molar on the lower jaw. The anterior edge (posterior edge) of the last molar forms its anterior border, while the anterior edge of the ascending ramus of the mandible forms its posterior border. This anatomical region plays a significant role in oral oncology due to its proximity to critical structures such as the mandible, muscles of mastication, and neurovascular bundles. The RMT is challenging to visualize and palpate, especially in patients with limited mouth opening, necessitating the use of radiological evaluations like Contrast-enhanced CT scans. When bony invasion is present, a combined modality treatment is typically recommended, involving surgery (segmental mandibulectomy) followed by postoperative adjuvant radiotherapy (PORT) or concurrent chemo-radiotherapy (POCRT). However, there is some debate regarding the management of smaller lesions in the RMT that do not have bone invasion in scans. Both primary radiotherapy (RT) and primary surgery have shown similar outcomes when bone invasion is absent.

In cases where surgery is the primary treatment choice, some surgeons advocate a more conservative approach, like a posterior marginal mandibulectomy (Type Ib/Ic MM), while others recommend a segmental mandibulectomy. Studies have shown, however, that a Type I MM provides an equivalent treatment outcome to a segmental mandibulectomy while preserving the mandible’s functional integrity (Pathak). Pathak et al. analysed the records of 130 consecutive retromolar trigone cancer patients who underwent marginal or segmental mandibulectomy at a tertiary care centre [5]. Although patients undergoing marginal mandibulectomy had a higher recurrence rate than segmental mandibulectomy (19% vs. 6%), the difference was not statistically significant. Moreover, a subsequent segmental mandibulectomy could salvage 67% of recurrences after a marginal mandibulectomy. This study concluded that segmental mandibular resection should be reserved for more invasive tumours. Additionally, a Brazilian study examined the recurrence and survival rates of patients with retromolar and advanced tonsil tumours with no invasion of the mandible treated between 1994 and 2001 [6]. There was no significant difference between marginal and segmental mandibulectomy regarding recurrence rates or overall survival (55% versus 45%). However, this cross-sectional study consisted of just 20 and 22 patients each in each arm, resulting in a small sample size. We also reported (Nair et al.) a series of 98 cases, where 56 patients underwent Type Ia, and 42 underwent Type I b/c marginal mandibulectomy, respectively. We observed no significant change in the local recurrence rate between anterior marginal or posterior marginal mandibulectomy [7].

Lower Gingivobuccal Sulcus Tumours

In 1988, McGregor et al. emphasised the occlusal surface, especially in non-irradiated mandibles as the root of entry for tumour from the floor of the mouth [8]. Later studies by Brown et al. [9] found no preferential entry of tumours through the periodontal membrane but noticed direct entry of the tumour at the point of abutment for both dentate and edentulous mandibles. Considering these points, larger and deeper tumours require segmental resection, whereas for smaller tumours, there is a need to consider the direct point of entry, which can be the closest border of the tumour with the mandible. Multiple studies have shown the oncological safety of marginal mandibulectomy especially when there is no cortical bone erosion or marrow involvement. For alveolar disease without bone erosion, a Type I marginal mandibulectomy with wide local excision should be sufficient.

Floor of Mouth and Tongue Cancers

Patterns of invasion and spread play an important role in the way the cancer spreads and the anatomical structure it will involve according to subsite. In the floor of mouth mucosa, the important anatomical barriers are the mandible laterally, mylohyoid muscle inferiorly, and the least path of resistance is the tongue medially. Thus, usually, FOM tumours abut the mandible rather than involving it directly. Often segmental mandibulectomy is performed to achieve clear margins. However, an oblique marginal mandibulectomy (Type II) or a vertical marginal mandibulectomy (Type III) can clear the disease that extends to the lingual aspect of the lower jaw, without compromising the stability or its continuity.