Tongue cancer incidence remains high, partly due to betel nut chewing, smoking and drinking habits (Cohen Goldemberg et al. 2018). At present, the treatment of tongue cancer is based on the patient's condition and individual conditions to develop a personalized plan, with the main treatment goals of tongue excision and simultaneous tongue reconstruction (Sinha et al., 2022). Resection of cancer lesion not only caused the destruction of the shape of the tongue, but also caused a series of oral function disorders such as swallowing and speech, which affected the normal life of patients in different degrees (Han et al. 2019). Over the years, researchers have focused on anatomical and functional repair methods to restore the form and function of tongue defects. With the advancement of multimodal therapy, the goal of tongue reconstruction has evolved from restoring shape to achieving both functional and morphological recovery, and various tissue flap repair techniques have been widely used in clinic, so it has become possible to reshape the original shape of patients' tongue (Leymarie et al. 2012).

The SGF is indicated for patients with oral defects of ≤4 cm2, where the sublingual gland blood supply is intact, and there is no invasion of the floor of the mouth. SGF is contraindicated in cases involving larger defects or those requiring free flap reconstruction. The sublingual gland flap (SGF) is an option for postoperative reconstruction of oral defects, but it remains underutilized by clinicians and is rarely reported in the literature. SGF can be used alone to repair postoperative oral defects, or it can be used in combination with other flaps as a way to repair deep oral tissue defects (Engel et al. 2010). The sublingual gland is the smallest of the three salivary glands and is located under the mucous membrane at the front of the floor of the mouth, above the mylohyoid muscle, deep in the sublingual crease wall, and on the lateral side of the mandible (Jose et al. 2020). SGF can migrate to almost any location in the mouth on the same side to cover soft tissue defects. Its blood supply comes from the submental and sublingual arteries and from the branches of the lingual and facial arteries, with accompanying veins (Jose et al. 2020). The abundant blood supply reduces the risk of flap necrosis. However, since the sublingual nerve and the submandibular gland duct are located near the gland, the preparation process of the sublingual gland flap requires very delicate surgical skills. Due to its small size, SGF is suitable only for repairing small to medium soft tissue defects (Wieczorkiewicz et al. 2024). Larger or complex defects require the use of free flaps or a combination of different flaps for repair and reconstruction (Eguchi et al. 2018).

This study aimed to assess the non-inferiority of SGF compared to primary suturing following T1-T2 tongue cancer resection, with a focus on functional outcomes.