Systematic review of minimally-invasive reconstructive options for oral cavity defects| ACTA Otorhinolaryngologica Italica

Abstract

The oral cavity is a primary site for malignant neoplasms of the head and neck region. Surgery, with or without adjuvant therapy, offers the highest probability of cure by focusing on radical tumour removal and organ function restoration. Reconstructive options are represented by local and free flaps, while small defects can be managed without reconstruction. For medium-sized defects without bone involvement, local flaps can be a good alternative to free flaps in selected patients. The purposes of this article are to analyse the main minimally-invasive reconstructive techniques in oral cancer surgery through a systematic review of the literature and develop a reconstructive algorithm based on the site and size of the defect. We defined minimally-invasive reconstruction as any reconstructive option not involving flap dissection from the neck or other distant areas from the oral cavity. Options considered include: local myo-mucosal or mucosal flaps (based on the facial or buccal arteries, and palatal flap), Bichat’s fat pad flap, and nasolabial flap. Use of biological or synthetic materials is also described. In selected patients with small to moderate-sized defects, the possibility of reconstruction with local flaps can be a viable option.

Introduction

The oral cavity is a primary site for malignant neoplasms in the head and neck region, with the majority being squamous cell carcinoma. Surgery, with or without adjuvant (chemo)radiotherapy, offers the highest probability of cure ^1,2. Surgical goals include radical tumour removal and restoration of organ function. Key functional aspects encompass speech, tongue mobility, swallowing, oral competence, and separation of the oral cavity from the nose and neck ³.

Reconstructive options are represented by local, loco-regional, and free flaps. Small defects can be managed without reconstruction ⁴. In these cases, the use of synthetic materials promote healing and aid postoperative pain control. For medium-sized defects without bone involvement, local flaps are good reconstructive alternatives to microvascular free flaps. For locally advanced tumours, free flaps are the most viable option ⁵, while loco-regional flaps (such as the pectoralis major or temporalis flap) are used in selected cases, for example, in patients not eligible for reconstruction with a microvascular flap or salvage reconstruction. The purpose of this article is to analyse the main minimally-invasive reconstructive techniques in oral cancer surgery through a systematic review of the literature and develop an algorithm based on the defect’s site and size.

Methods

This systematic review was designed using the PICO search strategy for qualitative questions and written in accordance with the PRISMA statement. We defined minimally-invasive reconstruction as any reconstructive option not involving flap dissection from the neck or other distant areas from the oral cavity. We included the following options: local myo-mucosal or mucosal flaps (flaps based on the facial or buccal arteries, and palatal flaps), Bichat’s fat pad flap, local skin flaps (nasolabial flap), and reconstructive options using biological or synthetic materials.

The literature search was conducted on October 1, 2023, in the PubMed database using the following search strings (“famm flap”[All Fields]) OR (“facial artery musculo-mucosal flap”[All Fields] OR “facial artery musculo-mucosal”[All Fields] OR “facial artery musculo-mucosal famm flap”[All Fields] OR “facial artery musculo-mucosal flap”[All Fields] OR “facial artery musculo-mucosal”[All Fields] OR “facial artery myo-mucosal flap”[All Fields] OR “facial artery myo-mucosal island flap”[All Fields] OR “facial artery myo-mucosal island”[All Fields] OR “facial artery musculo-mucosal flaps”[All Fields] OR “facial artery musculo-mucosal famm”[All Fields] OR “facial artery myo-mucosal”[All Fields]) AND ((((“cancer”[All Fields])) OR (neoplasm) OR (carcinoma)))); ((((((((((“buccinator flap”[All Fields] OR “buccinator flap procedure”[All Fields] OR “buccinator muscle”[All Fields] OR “buccinator musculo-mucosal flap”[All Fields] OR “buccinator musculo-mucosal”[All Fields] OR “buccinator musculo-mucosal flaps”[All Fields] OR “buccinator musculo-mucosal flap”[All Fields] OR “buccinator musculo-mucosal”[All Fields] OR “buccinator myo-mucosal”[All Fields] OR “buccinator myo-mucosal flap”[All Fields] OR “buccinator musculo-mucosal island”[All Fields] OR “Bozola flap”[All Fields])))))))))) AND ((((“cancer”[All Fields])) OR (neoplasm) OR (carcinoma)))); ((((“palatal muco-periosteal flap”[All Fields] OR “palatal muco-periosteal flaps”[All Fields])) OR (“palatal flap”[All Fields])))) AND ((((“cancer”[All Fields])) OR (neoplasm) OR (carcinoma)))); “nasolabial flap”[All Fields] OR “nasolabial flap reconstruction”[All Fields] OR “nasolabial flaps”[All Fields] AND ((((“cancer”[All Fields])) OR (neoplasm) OR (carcinoma)))) AND (Oral Cavity);(((((“Bichat”[All Fields]) OR (“buccal fat pad”[All Fields])) OR (“Bichat fat pad”[All Fields])))) AND ((((“cancer”[All Fields])) OR (neoplasm) OR (carcinoma)))) AND (Oral Cavity))))).

The reference lists of the articles identified were reviewed and cross-referenced to identify any additional relevant articles.

The inclusion criteria for the studies were as follows:

1. original articles published after January 1, 2000;
2. articles including patients reconstructed with one of the following techniques: local mucosal or myo-mucosal flaps, local skin flaps, and Bichat’s flap;
3. articles written in English, Italian, or German;
4. articles comprising at least 5 patients who met the inclusion criteria;
5. patients aged 16 years or older undergoing oncologic surgery of the oral cavity;
6. presence of adequate data on defect location, reconstruction, and outcomes.

The exclusion criteria used were as follows:

1. articles written in a language other than Italian, English, or German;
2. case reports or case series with fewer than 5 patients, meta-analyses, or systematic literature reviews;
3. articles on anatomical dissections;
4. patients with oral cavity defects due to non-oncologic surgery (traumatic, benign pathology, infectious diseases);
5. lack of sufficient data.

In the initial phase of the study, abstracts were selected for inclusion by two different authors (LG and VD). Full texts of the selected abstracts were then reviewed in detail. Only publications that clearly described the purpose and objectives, inclusion and exclusion criteria, with clear statistical data, reporting information on the surgical defect, success rates, and postoperative complications, were included. Eligibility for inclusion of the full-text articles was independently assessed by the same two above mentioned authors and, in case of uncertainty, discussed and decided by consensus.

For each reconstructive option, we collected key characteristics, various surgical flap preparation techniques, defect dimensions and locations, and any specific indications or contraindications.

Results

With the selected search criteria, 280 articles were found in the PubMed database. Six abstracts were added from the bibliography of the articles included, for a total of 286 articles examined. Seven articles were discarded because written in a language other than English, Italian, or German. The remaining 279 abstracts were reviewed by 2 different authors. After excluding case reports, case series with fewer than 5 patients, and patients operated on for non-malignant conditions, 67 articles published from January 1, 2000 until the search date were included for full-text review. Of these, 25 articles were discarded for the above-mentioned exclusion criteria. In the end, a total of 42 studies were included in our systematic review, as depicted in the PRISMA flow diagram (Fig. 1).

A total of 1322 patients were included. We categorised the articles into multiple groups based on the described local flap: facial artery-based flaps (facial artery myo-mucosal and Zhao flaps), buccinator flap (Bozola), palatal flap, nasolabial flap, and Bichat’s fat pad flap. Additionally, we considered reconstructive options with synthetic materials and non-reconstruction (Tab. I).

Myo-mucosal flaps pedicled on the facial artery

Regarding myo-mucosal flaps based on the facial artery, 15 articles with a total of 353 patients were included (Tab. II). Various techniques for harvesting buccinator flap were described: facial artery myo-mucosal (FAMM) flap, reverse flow FAMM flap with superior pedicle, facial artery myo-mucosal island flap (FAMMIF) or Zhao flap. The majority of patients presented with a defect in the oral floor, followed by the tongue, and, in some cases, reconstruction involved both the hard and soft palate. Defect sizes were specified in 5 articles (ranging from an average of 3.7x2.1 cm to 5.4x3.1 cm). In 6 articles, the defect size was described but precise measurements were not reported (but all defects were defined as small to medium-sized). Use of bite blocks in the early postoperative days was described in 2 articles. One study documented 4 cases of patients with double FAMM flaps.

Myo-mucosal flap based on the buccal artery

With regard to buccinator muscle flap, 5 articles were included, covering a total of 138 patients. The majority of patients presented defects in the tongue, oral cavity, palate, and buccal mucosa. Defect sizes were specified in only 2 of 5 articles, and ranged from 2 to 5 cm (Tab. III).

Palatal flap

Regarding the palatal flap, 6 articles were selected, involving a total of 175 patients. Most had a defect in the hard palate, while one study described its use for retromolar trigone and another for reconstruction of complex defects of the oral cavity. The defect sizes were specified in only one study (Tab. IV).

Fibroadipose Bichat’s flap

Regarding Bichat’s flap, 8 articles were included, involving a total of 156 patients. Most patients had a defect in the hard palate or buccal mucosa, while some patients had defects in other oral cavity sites such as the retromolar trigone. The defect sizes were specified in 6 of 8 articles, ranging from 3x1.5 cm to 5.5x4 cm (Tab. V).

Local skin flap: the nasolabial flap

Regarding local skin flaps, the only flap that met the inclusion criteria was the nasolabial flap. Eight articles related to such a surgical technique were included in the review, involving a total of 500 patients. Most patients had a defect in the tongue and oral pelvis, followed by the upper and lower gingiva, lip, buccal mucosa, vestibule, palate, and retromolar trigone. The defect sizes were specified in only 4 of 8 articles (Tab. VI).

Discussion

The reconstruction of defects resulting from oral cavity oncologic surgery is often imperative, not only for aesthetic reasons but primarily for functional purposes. The primary goal of reconstruction is to ensure the separation of the oral cavity from other anatomical spaces, avoiding salivary fistula and infection ⁴. Secondly, it aims to restore the function of the affected subsite, ensuring an acceptable quality of life. The optimal method for oral cavity reconstruction depends on various factors such as site, type, and amount of tissue to be replaced. The gold standard in reconstructing complex oral cavity defects is currently achieved through microvascular free flaps. However, this may not always be the best option due to donor site morbidity, need to explore the neck for vessels receiving the anastomosis, and, especially, the prolonged operative times, which may not be tolerable for patients with compromised systemic conditions and significant comorbidities. Additionally, it requires considerable expertise and often a double surgical team. In selected cases of patients with medium- or small-sized mucosal defects that do not require extensive reconstruction, where there is no need for resection connecting the oral cavity and the neck, or for patients who cannot tolerate prolonged anaesthesia, a viable reconstructive option is provided by local flaps ⁵. We will discuss the results obtained from the literature review, highlighting the advantages and disadvantages of each of these flaps.

Myo-mucosal flap pedicled on the facial artery

The initial account of a FAMM flap for head and neck reconstruction was reported by Pribaz and colleagues ⁶. Zhao et al. subsequently introduced a variation of this flap design, known as the FAMMIF ⁷. In the literature, there is much confusion regarding the nomenclature of these two flaps, and often the abbreviations are used ambiguously. The FAMM flap is an axial flap centred around the facial artery, featuring an oblique orientation that extends from the retromolar trigone to the ipsilateral gingiva-labial sulcus at the level of the alar margin. It can be pedicled either in a downward direction (with anterograde arterial flow) or upward (with reverse arterial flow or RFAMM), depending on the specific reconstructive requirements (Fig. 2) ⁷.

RFAMM can be employed to close defects in the anterior hard palate, maxillary alveolus, nasal septum, and upper lip. In contrast, when the FAMM flap is pedicled in a downward direction, it is particularly suitable to close defects in the posterior hard palate, soft palate, lower lip, mandibular alveolar region, and vestibule ⁸.

The FAMMIF is a variant of the FAMM flap, firstly described by Zhao in 1999. Employing this approach allows for the elevation of nearly the entire cheek mucosa as an independent island flap. While the angiosome of the buccal artery is removed, it is consistently incorporated into the flap to enhance peripheral vascularisation ⁹. This flap is a valuable choice to reconstruct defects in the palate, pharynx, tongue, and floor of the mouth. It consists of mucosal, submucosal, and buccinator muscle tissues. The FAMMIF is particularly suitable to address small to moderate defects in the oral cavity and oropharynx, while larger or composite defects still primarily rely on revascularised free flaps as the gold standard reconstructive option ¹⁰. More specifically, the FAMMIF is recommended for small to moderate defects (following the resection of T1-T2 tumours). In general, the FAMMIF is well-suited for addressing defects ranging from 4 to 10 cm in size, especially when there is the need for reconstructing with thin, flexible mucosal tissue closely matching the texture of the tissue removed ¹⁰.

It is worth considering a significant adaptation of the FAMMIF flap: the tunneled facial artery myo-mucosal island flap (t-FAMMIF). It is harvested on the inner side of the cheek, traverses a neck tunnel, and then enters the pharynx or oral cavity through a second tunnel. It offers an extensive range of rotation, making it possible to reconstruct nearly every region within the oral cavity and oropharynx, including those on the opposite side ⁹.

The FAMM flap offers numerous advantages. To begin with, it is a thin and flexible flap that adheres to the “replace like with like” principle. It involves a relatively brief dissection phase. The donor site morbidity is minimal, and it does not result in any external scar. Furthermore, prior radiation therapy in the area of the flap is not a contraindication for its use, since it maintains its integrity even after radiation ¹¹.

Nevertheless, it also presents certain drawbacks. In dentate patients, the FAMM flap necessitates tooth extraction or use of a bite block during the healing process and a second surgical procedure for pedicle section ^9,10. Regarding the t-FAMMIF, thoroughly dissecting the facial vessels and establishing tunnels between the mandible and cheek, as well as between the neck and the oral cavity, enable the flap to be repositioned independently from the dentition, eliminating the necessity for additional procedures to divide the pedicle ¹⁰. Additionally, while the FAMM has a broad range of rotation and a favourable length-to-base ratio (5:1), these factors can still pose limitations for more extensive and anterior tongue reconstructions, as well as for defects on the contralateral side ¹¹.

Neither FAMM nor FAMMIF are recommended when there is widespread dysplasia in the oral cavity. However, as reported by Ferrari et al., if it is performed carefully and adjuvant radiotherapy is administered as usual when indicated, neck dissection with preservation of the facial artery and vein does not alter the rate of regional recurrences, confirming the oncologic safety of these flaps in oral cavity reconstruction ¹². Both flaps address surgical defects within a short timeframe. There is no need for specific microvascular training or preoperative vascular evaluation. Moreover, morbidity is generally low, with flap dehiscence being the most commonly observed postoperative complication ¹⁰.

Myo-mucosal flap based on the buccal artery

The buccinator myo-mucosal flap is an axially vascularised flap that can be based on the facial or buccal arteries. It comprises the buccal mucosa and buccinator muscle, a thin muscle that forms the scaffolding of the cheek. It originates from the external surface of the alveolar processes of the mandible and maxillary bone last three molars. Posteriorly, it originates from the pterygomandibular raphe and attaches anteriorly to the orbicularis oris muscle. Laterally, it contacts the ramus of the mandible, masseter, medial pterygoid muscle, Bichat’s bulla, and the buccopharyngeal fascia. Medially, it is covered by the cheek submucosa and mucosa ³⁰.

Regarding its vascularisation, the buccal, facial, and posterosuperior alveolar arteries constitute the main blood supply to the muscle. The buccal artery is a branch of the internal maxillary artery and vascularises the posterior half of the muscle. It runs antero-inferiorly under the lateral pterygoid muscle to reach the posterior half of the muscle, where it anastomoses with the posterior vestibular branch of the facial artery. The facial artery runs around the lower border of the mandible at the anterior margin of the masseter muscle. It supplies numerous branches to the buccinator muscle, the largest of which is the posterior buccal, which vascularises the posterior half of the muscle. The facial artery gives one to three inferior buccal branches to supply the lower half of the muscle, then continues in an anterosuperior direction to give off 3-5 small anterior buccal branches to the anterior half of the muscle. The posterosuperior alveolar artery, collateral of the internal maxillary artery, supplies two small branches to the muscle, which enter it posteriorly and superiorly, and the infraorbital artery gives off some small branches that enter it antero-superiorly. All these arteries form a complex vascular system on the lateral surface of the muscle and within its fibres ⁷.

Venous drainage occurs through the pterygoid plexus and the internal maxillary vein, which lies posterior, superior, and superficial to the buccinator muscle and drains into the buccal vein through the deep facial vein. Anteriorly, the deep facial vein drains into the external (or anterior) facial vein. Sensory innervation occurs through the long buccal nerve, a branch of the maxillary nerve, which runs with the buccal branch of the internal maxillary artery. The motor innervation of the buccinator muscle consists of the temporal and cervical divisions of the facial nerve, which form a plexus near the buccal fat pad. Stensen’s duct also has a critical anatomical relationship with the buccinator muscle, crossing it at the second upper molar.

The buccinator muscle flap can have an anterior, posterior, or superior base depending on the predominant vascularisation ³¹. The anatomical limits of the flap are the parotid duct superiorly, the oral commissure anteriorly, and the pterygomandibular raphe posteriorly. The lower limit depends on the amount of tissue required, but it is possible to raise a flap up to 7x5 cm ³².

This flap is flexible, versatile, and, unlike most free flaps, provides mucosal rather than exclusively cutaneous coverage. Furthermore, the donor site can be directly closed for defects smaller than 2.5 cm.

Posteriorly based buccinator flap (Bozola)

Bozola et al. ³⁰ first described an axial myo-mucosal flap based posteriorly on the buccal artery. Once the buccal artery has been identified by Doppler ultrasound, the buccal mucosa and the buccinator muscle are incised at the level of the buccopharyngeal fascia and the flap raised in an anteroposterior direction in the loose areolar plane between the buccinator muscle and the buccopharyngeal fascia. The buccopharyngeal fascia is preserved because it prevents herniation of the buccal fat pad and avoids injury to the facial nerve branches. The small branches of the facial artery are ligated, as are the anterior venous tributaries of the pterygoid plexus. The dissection proceeds posteriorly to the pterygomandibular raphe anteriorly, where the main neurovascular bundle enters the flap ³⁰.

A variant of the previously described flap is the posteriorly-based island pedicled buccinator flap, in which the mucosa is incised circumferentially and separated from the adjacent mucosa. However, the flap remains attached to the underlying pedicle, which feeds it via the buccal artery. This modification increases the mobility of the flap. This concept derives from subcutaneous island pedicled skin flaps ^33,34.

Buccinator-based myo-mucosal flaps are not suitable for coverage of oral defects larger than 7 cm. Stensen’s duct pierces the buccinator muscle slightly above its centre. Considering a safe distance of 0.5-1 cm from this orifice, only half of the muscle and overlying mucosa can be used for reconstruction. Relocating the Stensen’s duct adds more mucosa, but requires significantly more expertise. Primary donor site closure is possible in defects < 2.5 cm. More significant donor sites defects are managed by mobilising the buccal fat pad, which is progressively re-epithelialised. Other options are represented by skin graft or masseter muscle flap.

However, these flaps are remarkably elastic and malleable and can be stretched to accommodate complex-shaped defects. The arc of rotation of the posteriorly based flaps pedicled on the buccal artery allows reaching the velar, palatine, lateral pharyngeal, and retromolar trigone sites. The buccinator myo-mucosal flap, in its variants, has notable advantages compared to reconstruction with free flaps. It is ideal for surgical units with no experience in microvascular free flaps and fragile patients who cannot tolerate excessively long surgical times ^32,33.

Palatal flap

Benign or malignant tumours of the oral cavity, nasal fossa, or paranasal sinuses sometimes require resection of the hard palate to varying degrees. There are different classifications of maxillectomies, mainly based on the extent of resection according to a vertical, horizontal, or transverse orientation ³⁶.

The palatal flap is an axial flap receiving its vascular supply from the greater palatine artery which, emerging from the greater palatine foramen, runs anteriorly to join the nasopalatine vessels at the level of the incisive foramen (Fig. 3) ³⁷.

It provides adequate volume and length with a high success rate due to the robustness of palatal muco-periosteum. This promotes local healing with its own vascular supply and is indicated for the reconstruction of small defects, involving less than one-third of the hard palate with oro-antral fistula, as well as for the reconstruction of partial resections of the soft palate, tonsillar region and medial portion of the retromolar trigone ^38-40.

The advantages of the palatal flap are many, including proximity, local availability with minimal donor site morbidity, complete re-epithelisation in 4-6 weeks, little shrinkage, tensile strength with reliable blood supply, preservation of local sensitivity and good mobility. In irradiated patients healing will proceed at a slower pace, taking 6-8 weeks to complete. Limitations are mainly the small size and the limited possibility of axial rotation. The latter is facilitated the greater the length of the flap and if an amount of soft tissue is preserved around the pedicle to increase its torsional strength. Furthermore, by dissecting and skeletonising the greater palatine neurovascular pedicle at its emergence, an additional length of approximately 1 cm can be achieved ^41,42. Complications are rare and include haemorrhage and partial or complete necrosis of the flap.

For defects greater than one-third of the palate, the palatal flap can be combined with a buccal inversion flap, and then lifted and inverted to rebuild the mucosa of the nasal floor. The advantage of two-layer closure is the epithelial coverage on both sides of the communication. This is consequently associated to a reduction of flap contraction and risk of infection ³⁹.

In most cases the size of the palatal defects decreases during healing, thanks to its marginal re-epithelisation and temporary prosthetic obturator to close the oro-antral fistula. Therefore, choosing a two-stage closure allows tissue gain and, in selected cases, the possibility of closing even major defects with a palatal flap ^39,40.

A disadvantage of the local palatal flap is that it is not applicable in case of defects larger than 50% of the palatal surface. These should therefore be treated by means of obturators or loco-regional or revascularised flaps ^43-45.

Bichat’s flap

One of the most effective tools in the reconstruction of intraoral defects is the Bichat‘s fat pad or, as it is commonly known, the buccal fat pad (BFP). First described by Bichat in 1801 as ‘Bichat’s lobule’, the BFP lies in the masticatory space, separating the muscles from each other and acting as a cushion ^46,47. It is an anatomically distinct entity characterised by a biconvex, encapsulated shape. The BFP has a central body and four separate processes: buccal, pterygoid, pterygopalatine, and temporal ^48,49.

The popularity of BFP as a graft material for closure of intraoral defects, especially oro-antral and oro-nasal fistulas, is mainly due to its ease of access and considerable vascular supply ^47,53,54. It is therefore very important to preserve the thin capsule of the flap during harvesting, so as not to damage its delicate blood vessels and compromise its viability ⁵⁵.

Re-epithelisation of the BFP flap usually occurs within 4 weeks, with excellent functional and aesthetic results ^47,53,54. These attributes make it an ideal option for the reconstruction of specific defects, particularly those small to medium-sized, located in the maxilla, extending to the retromolar trigone and palate ⁵⁵. The size of the defect is crucial in deciding on the use of the BFP. For maxillary defects, the ideal size for such a reconstructive tool should be approximately 4 cm while, for buccal or retromolar defects, it can be up to 6 cm ^49-51.

In conclusion, the main advantages of BFP include its ease of harvest and high adaptability with very low morbidity and minimal failure rates. However, its main limitations are that its use is limited to small to medium defects without providing significant volume. Additionally, it is contraindicated in patients with malar hypoplasia ^47,56-59.

Nasolabial flap

The nasolabial flap is a widely used flap to reconstruct head defects. The most used approaches are the pedicled subcutaneous nasolabial flap with an upper or lower base, and the pedicled island nasolabial flap on the facial artery and vein (Fig. 4). For the reconstruction of intra-oral defects, a lower-based flap is generally preferred ⁷⁰.

The skin of the nasolabial fold is supplied from below by multiple branches that arise from the alar branch of the superior labial artery, which in turn arises from the facial artery, and by branches that arrive from the angular artery, which also derives from the facial artery. Laterally, the skin is supplied by the infraorbital artery, a branch of the ophthalmic artery, and by a branch originating from the temporal artery: the transverse facial artery. Thanks to this extensive blood supply, it is possible to design a flap with an inferior or superior base that has as its pedicle the facial or the infraorbital and transverse facial arteries, respectively ⁷¹. The skin that can be harvested extends from the medial canthus of the eye to the lower edge of the jaw, and this area is generally hairless if we exclude the lower part of the cheek in men ⁷². To transpose the flap into the oral cavity, it is necessary to create an access through the buccinator muscle and pass the flap through it. The surgeon can, therefore, decide to transfer the flap in a single-step operation; in this case, it is preferable to de-epithelialise the base of the flap, thus allowing primary closure of the donor region, or to perform the reconstruction in two steps, initially suturing the flap at the intraoral level and, approximately three weeks later, sectioning the pedicle thus allowing complete closure of the donor site ⁷³.

A widespread variant of the nasolabial flap is represented by the island nasolabial flap, which involves the identification of the facial artery and vein and their skeletonisation up to their origin. In this way, the intrinsic problems of the nasolabial flap are overcome, i.e. the presence of a short pedicle that does not allow reaching defects distant from the donor site and the risk of damaging the pedicle in dentate patients. The pedicle in this flap is very long and allows the reconstruction of defects even contralateral to the harvesting site, reaching the recipient site via a tunnel through the oral floor ⁶².

The nasolabial flap represents a good alternative to reconstruct small and medium-sized intra-oral defects. Different data are reported in the literature: according to some authors, a single nasolabial flap can cover defects of approximately 3 cm, while others repaired defects of up to 5x5 cm ^66,74. However, in case of more extensive defects, performing a double nasolabial flap is also possible. The patient of choice for this flap is elderly, where the skin redundancy and laxity allow large flaps to be taken, still allowing a primary closure of the donor region. Moreover, in the edentulous patient the probability of injuring the pedicle is inferior ⁷². However, the presence of teeth is not an absolute contraindication, as the nasolabial flap can be used in all cases of reconstruction of the buccal mucosa ipsilateral to the harvesting site. In contrast, in cases of reconstruction of the oral floor or tongue, an island nasolabial flap can be used, as previously described ^69,73.

As emerges from this analysis, the nasolabial flap is burdened by few serious complications and, in selected cases, can be a valid reconstructive alternative for oral cavity defects.

Biological and synthetic materials and non-reconstruction

In some situations, using flaps to reconstruct the oral cavity may not be possible or may result in over-treatment for minor defects. In such circumstances, one can rely on various materials and strategies. When faced with bone defects in the oral cavity, bone replacement and reconstruction are essential to restore structure and function. Various bone filling and replacement materials are available, although they are not routinely used in surgical practice. Hydroxyapatite and tricalcium phosphate are similar to the mineral component of bone and are used to fill minor bone defects, but are gradually reabsorbed over time. In addition to these, synthetic materials based on ceramics or polymeric resins can be exploited to fill bone spaces and improve the stability of dental prostheses or implants. In case of mucosal or soft tissues defects, specific filling materials are crucial. Some options include the use of synthetic materials such as expanded polytetrafluoroethylene, which can be used to create a mechanical barrier and promote soft tissue regeneration. In the context of future regenerative medicine, laboratory cultivation of epithelial and connective cells will probably create new tissues to routinely reconstruct mucosal defects ⁷⁵.

Alternatively, other biological materials can also be used, such as bovine pericardium ⁷⁶ or other biological matrices of bovine collagen ⁷⁷, which can represent a simple and rapid solution for defects of limited thickness. Another type of material that can be used is a matrix of thrombin and fibrinogen which combines repair with the capacity for haemostasis ⁷⁸. This matrix can be helpful for small defects and associated with reconstruction by other methods (such as local flaps or primary closure).

The choice of materials is closely related to the size and location of the defect, the patient’s functional and cosmetic needs, as well as the availability of resources and surgical skills. Accurate evaluation of each case is essential to determine the most appropriate strategy. In general, non-reconstruction should be limited to cases in which the defects are small-sized, while the use of synthetic or biological materials to replace the patient’s normal oral mucosa may favour and accelerate the healing process with better functional outcomes.

Proposal for a reconstructive algorithm

Based on the data gathered in our systematic review, we formulated a reconstructive algorithm for minimally-invasive reconstructive options, taking into account the site and size of the defect. Specifically, local options are preferable when defects are not extensive and do not involve multiple tissue types ⁷⁹, such as bone segments or large muscular volumes (Fig. 5). Furthermore, mucosal defects to be reconstructed by local flaps should have small to medium dimensions, typically not exceeding 20 cm², although some authors have reported exceptional cases of larger defects successfully reconstructed with these techniques.

This reconstructive approach is ideally suited for patients who do not require neck dissection for oncological reasons, thereby avoiding the associated morbidity linked to neck dissection for isolating vessels needed for vascular anastomosis, as required for microvascular flaps, or creating tunnels for the passage of pedicle in the case of locoregional flaps (e.g., pectoralis major or temporal flaps). It also proves to be a crucial option for patients who are not suitable for lengthy surgeries, such as those necessary for microvascular flap reconstruction.

Careful consideration should be given to the option of non-reconstructing the defect and protecting it with biological materials or allowing healing through secondary intention. This choice is preferable in cases involving a small, predominantly mucosal defect, such as in the genial mucosa or tongue, affecting only the intrinsic musculature, where the risk of salivary fistula or worsening functional outcomes is not anticipated.

Using data extracted from the present analysis, we systematically categorised different flaps based on the type of defect they were employed for. Subsequently, we formulated a proposed decisional algorithm outlining the use of local flaps, structured around the specific defect site (Tab. VII, Fig. 6).

Conclusions

In selected patients with small to moderate-sized defects, the possibility of reconstruction with local flaps can be a viable option. This is particularly true for patients who are not suitable for microvascular surgery and for those in whom neck dissection is not necessary, and in cases where harvesting a flap from a donor site outside the head and neck region would increase morbidity not only at this level but also in the neck, either due to the passage of the pedicle or the preparation of vessels for microvascular anastomoses. Throughout the decision-making process, it is crucial to consider the choice of not reconstructing the defect, opting for healing by secondary intention, or using biological materials for coverage, especially when the defect is solely mucosal and does not entail risks of oro-cutaneous or oro-antral fistulas or predictable functional deficits.

Acknowledgements

The authors would like to thank Michele Barbara for the valuable invitation to participate in and contribute to this work.

Conflict of interest statement

The authors declare no conflict of interest.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Author contributions

LC, EF, SB, MA, VD, CA, GN, AN, FZ: conceived the study, collected the data and wrote the paper; RA: corrected the paper; LG: conceived the study and wrote and corrected the paper.

Ethical consideration

The research was conducted ethically, with all study procedures being performed in accordance with the requirements of the World Medical Association’s Declaration of Helsinki.

Figures and tables

Figure 1.PRISMA flow diagram of the review.

Figure 2.Myo-mucosal flap pedicled on the facial artery branches.ECA: external carotid artery; FA: facial artery; IMA: internal maxillary artery; SD: Stensen’s duct.

Figure 3.Palatal flap pedicled on the greater palatine artery.

Figure 4.The nasolabial flap pedicled on the facial artery and vein.

Figure 5.Decisional algorithm for use of minimally-invasive options in oral cavity reconstruction.

Figure 6.Decisional algorithm for use of minimally-invasive options in oral cavity reconstruction.FAMM: facial artery myo-mucosal; t-FAMMIF: tunneled facial artery myo-mucosal island flap; RFAMM: reverse flow FAMM; FAMMIF: facial artery myo-mucosal island flap.

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