**4.1 Floor of mouth**

*Oral Diseases*

discussing pros and cons of reconstruction.

**2. Anatomic landmark**

**3. Defect characteristics**

infection, or a permanent scar.

**4. Specific subsites**

excluded.

defect that may affect a complex functional unit that could include the mucosa, muscle, bone, skin, or a combination of them, which additionally may develop a continuity solution that creates a communication between the oral cavity with the neck and its subsequent salivary fistula, infection, risk of a major vessel blood bleeding or carotid blowout, and death. The reconstruction might be done just with a primary closure and skin graft or may be left to heal by second intention with no closure; some cases will need a pediculate, local, or regional flap, and in complex and huge defects, a microvascular free flap might be needed. Currently there is a trend to perform a microvascular reconstruction for most of the defects, but even in a two-team approach, the microvascular reconstruction increases the cost and duration time of the surgery; furthermore some health centers lack surgeons with the necessary skills to perform a microvascular surgery. The purpose of this chapter is to review the state of art in oral cavity reconstruction after an oncological resection and especially provide a rational approach to reconstruct each defect in order to restore it as similar as normal tissue before resection,

The oral cavity begins at the lips and ends at the anterior surface of the faucial arch. It is lined by squamous epithelium with interspersed minor salivary glands. It contains the lips, buccal mucosa, mandibular and maxillary alveolar ridge, retromolar trigone, hard palate, floor of the mouth, and anterior oral tongue. Motor innervation of intrinsic musculature is supplied by the hypoglossal nerve and sensation is provided by trigeminal nerve V2 and V3 branches. The sensation of the anterior two-thirds of the tongue is provided by the lingual nerve (CN V3), and its taste comes via the chorda tympani (CN VII) [3]. For the purposes of this chapter, only the proper oral cavity is considered, so lip reconstruction is

Assessing the characteristics of the defect is the first step to decide which is the best option to reconstruct. The size and specific subsite of the primary resection including its function will determine the need for subsequent reconstruction. Small or medium defects may not disturb function, so minimal intervention to reconstruct is necessary; on the other hand, composite defects that include several units and structures like the muscle, mucosa, bone, or even skin can affect the function in many ways, so in order to restore it, a specific composite tissue is needed, which is also a technique to avoid scars, nonfunctional tissue, or retractions with its subsequent unit dysfunction. Previous treatment like chemotherapy and especially radiation will also entail special needs in terms of reconstruction since providing a new normal tissue is essential to prevent local complications like fistula, dehiscence,

With the aim to choose correctly from a range of different technics, although it is frequent to face a combination of subsites and structures after surgical resection,

each subsite must be considered independently to assist the decision.

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The subsite floor of mouth (FOM) is limited anteriorly by the inferior alveolar ridge, posteriorly by the ventral surface of the lingual tongue, and laterally by the anterior tonsil pillar. The FOM avoids the spillage of saliva to the neck and is also necessary to support the tongue in speech and deglutition as well as to maintain the humidity of the mouth due to the big amount of minor salivary glands and to the outlet of the submandibular gland duct. The resection may result in a small or big defect that could or could not include the mucosa, bone and skin. The main goal of reconstruction is to restore the anatomic limits of the sulcus to avoid communication with the neck with the corresponding spillage of saliva and food, and to avoid retraction or fixation of the tongue then maintaining the adequate tongue mobility to support articulation and speech as well as allowing the tongue to move freely to push the food bolus back.

### *4.1.1 Small defects*

A very small deformity could be let alone without closure and permit healing by second intention with a granulation tissue. A facial artery myomucosal flap (FAMM), which blood supply is provided by the facial artery, could similarly be used for a defect limited up to a width of 2 cm and permit the primary closure of the donor site [4]. A split-thickness skin graft (STSG) or a full-thickness skin graft (FTSG) could be used for a defect smaller than 3–4 cm that does not spare the suprahyoid musculature or expose the bone (**Figure 1a** and **b**). The graft is usually secured with a pad dressing, which is removed 6–7 days after surgery. Usually remucosalization can be expected, and complete healing is obtained in about 4 weeks. The restriction to the skin graft is related to the difficulty to maintained it insetted due to its exposition to swallowing movements.

The advantage to let the defect to granulate by itself is the shortest time of the procedure; however, it usually takes up to 3 weeks to obtain a complete healing, implying some minor disturbances for the patient including pain and difficulty to swallow. The disadvantage of the graft is the secondary scar of the donor site but is offsetted by the result in the zone of resection and a shortened time of recovery.

#### *4.1.2 Medium defects*

For FOM defects up to 6 cm which may include a limited bone exposure, a regional pediculate flap can be employed to reconstruct; the most used are the

**Figure 1.** *(a) FOM resection and (b) skin graft.*

submental (SMF) and the supraclavicular flap (SCF). Additionally, in that kind of defects, especially when postoperative radiotherapy is projected, a pediculate flap must be planned if possible.
