A comparative study of epithelialization of subcutaneous fascial flaps and muscle-only flaps in the oral cavity. A rabbit model

Vascularized fascial flap for reconstruction of combined oral mucosa-mandibular defects: The multi-modal biological assessment

OBJECTIVE

The reconstruction of composite defects in the oral and maxillofacial region using vascularized fascial flaps, such as the fibular, iliac, and temporal fascial flaps, has gained increasing attention among surgeons. However, there remains uncertainty regarding the suitability of fascial flaps as transplants, as well as their healing processes and outcomes, due to their non-mucosal nature. This study aims to comprehensively assess the biological aspects of vascularized fascial flaps at clinical, histological, and genetic levels, with the goal of providing essential biological references for their clinical application.

STUDY DESIGN

This study enrolled three patients who underwent reconstruction of combined oral mucosa-mandibular defects using fibular vascularized fascial flaps between 2020 and 2023. Data regarding changes in the appearance of the fascial flaps, bulk-RNA sequencing, and histological slices of initial fascia, initial gingiva, and transformed fascia were collected and analyzed.

RESULTS

Within three months, the fascial flaps exhibited rapid epithelial coverage and displayed distinct characteristics resembling mucosa. High-throughput RNA sequencing analyses and histological slices revealed that the transformed fascia exhibited tissue structures similar to mucosa and demonstrated unique advantages in promoting blood vessel formation and reducing scarring through the high-level expression of relevant genes.

CONCLUSION

These findings emphasize the potential and feasibility of utilizing vascularized fascial flaps for oral mucosa reconstruction, establishing their unique advantage as transplant materials, and providing significant biological information and references for their selection and clinical application.

Two-Layer Palatal Reconstruction Reduces Postoperative Intraoral Complications in Head and Neck Surgery

BACKGROUND

Although microvascular free flaps are commonly performed and have high success rates, postoperative oronasal fistulas or infections do occur. The authors hypothesized that a two-layer closure is effective for prevention of intraoral complications.

METHODS

Patients who underwent palatal reconstruction with a microvascular free flap were evaluated retrospectively. The cases were divided into two groups (palatal reconstruction with or without a two-layer closure). A two-layer closure involves unilateral reconstruction with a free flap, then reconstruction of the nasal lining with a local flap or folding free flap. The postoperative complication rates between these two groups were compared.

RESULTS

One hundred fifty-five cases were evaluated. A two-layer closure was performed in 65 cases (41.9 percent). The incidence of infections, dehiscence of the recipient site, and oronasal fistula were significantly higher in the single-layer closure group than in the two-layer closure group [10.0 percent versus 0 percent (p = 0.011); 15.6 percent versus 4.6 percent (p = 0.036); and 17.8 percent versus 4.6 percent (p = 0.013), respectively].

CONCLUSIONS

A two-layer closure in palatal reconstruction was shown to reduce the rate of infection, intraoral wound dehiscence, and oronasal fistula in the current study. A two-layer closure provides greater support and stability and reduces the risk of failure in reconstruction of the palate with a microvascular free flap.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Oropharyngeal reconstruction with a pedicled submandibular gland flap

Locoregional flaps are widely used for reconstruction of small and medium defects in the oral cavity. The submandibular gland flap is a pedicled flap, which derives its blood supply from the facial artery, based on the submandibular gland. We describe the use of the flap in 20 patients who required oropharyngeal reconstruction with a pedicled submandibular gland flap after resection of a tumour between July 2012 and October 2014. Patients with squamous cell carcinoma were excluded. All flaps were pedicled on the facial vessels (inferiorly in 17 patients and superiorly in 3). The indications were: reconstruction of intraoral mucosal defects (n=13), filling the parapharyngeal dead space (n=6), and obliteration of the mastoid (n=1). All the flaps atrophied, but with no clinical effect. One patient developed partial loss of the flap, and one early leakage. There were no cases of xerostomia, and no signs of recurrence during the postoperative follow-up period of 3-26 months. The flap is useful, as it is simple and reliable for reconstruction of small to medium oropharyngeal defects in carefully selected cases, and gives good cosmetic and functional results.

Fibula osteo-adipofascial flap for mandibular and maxillary reconstruction

BACKGROUND

The fibula free flap is a reliable method for reconstructing composite head and neck defects. However, its skin paddle has drawbacks, including its thickness, hair-bearing surface, desquamation, difficulty insetting it into maxillary defects, and the potential need for skin-grafting the donor site. The fibula osteo-adipofascial flap (FOAFF) is a modification of the fibula flap that overcomes these problems.

METHODS

A retrospective study of 6 consecutive patients who underwent FOAFF reconstruction was evaluated for outcomes and complications.

RESULTS

The mean follow-up was 22.6 months. All flaps survived, with complete oral mucosalization by 7 weeks. Four patients had dental implants placed at the time of reconstruction. Two patients received radiation therapy. Aside from loss of the labial sulcus in anterior maxillary reconstructions, complications were negligible.

CONCLUSION

The FOAFF is useful for reconstructing defects requiring bone, soft tissue, and mucosal replacement without the disadvantages of the traditional fibula skin paddle.

Evaluation of soft tissue coverage over porous polymethylmethacrylate space maintainers within nonhealing alveolar bone defects

Current treatment of traumatic craniofacial injuries often involves early free tissue transfer, even if the recipient site is contaminated or lacks soft tissue coverage. There are no current tissue engineering strategies to definitively regenerate tissues in such an environment at an early time point. For a tissue engineering approach to be employed in the treatment of such injuries, a two-stage approach could potentially be used. The present study describes methods for fabrication, characterization, and processing of porous polymethylmethacrylate (PMMA) space maintainers for temporary retention of space in bony craniofacial defects. Carboxymethylcellulose hydrogels were used as a porogen. Implants with controlled porosity and pore interconnectivity were fabricated by varying the ratio of hydrogel:polymer and the amount of carboxymethylcellulose within the hydrogel. The in vivo tissue response to the implants was observed by implanting solid, low-porosity, and high-porosity implants (n = 6) within a nonhealing rabbit mandibular defect that included an oral mucosal defect to allow open communication between the oral cavity and the mandibular defect. Oral mucosal wound healing was observed after 12 weeks and was complete in 3/6 defects filled with solid PMMA implants and 5/6 defects filled with either a low- or high-porosity PMMA implant. The tissue response around and within the pores of the two formulations of porous implants tested in vivo was characterized, with the low-porosity implants surrounded by a minimal but well-formed fibrous capsule in contrast to the high-porosity implants, which were surrounded and invaded by almost exclusively inflammatory tissue. On the basis of these results, PMMA implants with limited porosity hold promise for temporary implantation and space maintenance within clean/contaminated bone defects.

Surface characteristics of biomaterials used for space maintenance in a mandibular defect: a pilot animal study

PURPOSE

The purpose of the present study was to evaluate the effect of implant porosity on wound healing between solid and porous implants placed within a bony mandibular defect with intraoral exposure.

MATERIALS AND METHODS

Solid poly(methyl methacrylate) (PMMA) implants similar to those used currently in clinical space maintenance applications in maxillofacial surgery were compared with poly(propylene fumarate) implants that contained a porous outer surface surrounding a solid core. A 10-mm diameter nonhealing bicortical defect with open communication into the oral cavity was created in the molar mandibular region of 12 adult male New Zealand white rabbits. Of the 12 rabbits, 6 received the hybrid poly(propylene fumarate) implants and 6 received the solid PMMA implants. At 12 weeks, the rabbit mandibles were harvested and sent for histologic staining and sectioning.

RESULTS

Gross inspection and histologic examination showed all 6 poly(propylene fumarate) implants to be intact within the defect site at the termination of the study period, with 3 of the 6 specimens exhibiting a continuous circumferential soft tissue margin. In contrast, 5 of the 6 PMMA-implanted specimens were exposed intraorally with an incomplete cuff of soft tissue around the implant. One of the PMMA-implanted specimens exhibited complete extrusion and subsequent loss of the implant. Fisher's exact test was used to compare the occurrence of oral cavity wound healing between the 2 groups (P = .09).

CONCLUSIONS

Although statistically significant differences between the 2 groups were not seen, our results have indicated that advantages might exist to using porous implants for space maintenance. Additional study is needed to evaluate these findings.

The superficial inferior epigastric artery fascia flap in the rabbit

In reconstructive surgery, fascial flaps provide thin, pliable tissue for mucosal closure or serve as a highly vascularized support for skin grafts. Their angiogenic potential is used for experimental neovascularization of avascular tissue grafts. However, most fascial flaps in animal surgery have random pattern design with short reach. As a pilot study for a femur revascularization project in rabbits, a new axial fascial flap is described based on the superficial inferior epigastric (SIE) vessels. They were used in this species previously only as ligated bundles or in fasciocutaneous flaps. The topographical anatomy of the SIE-vessels, lower abdominal fascia, and panniculus carnosus are outlined. The angiogenic capabilities are demonstrated microangiographically by abundant vessel formation in a femur allograft. Used in a pedicled fashion, this flap is an alternative to femoral and saphenous vessels for prefabrication or revascularization procedures in the lower abdomen, genital area, and thigh. Distant recipient sites seem possible with microsurgical transfer.

Epithelialization Process of Free Fascial Flaps Used in Reconstruction of Oral Cavity Mucosa Defects in Dogs

Bare free fascial flaps are increasingly used for restoration of soft-tissue defects of the oral cavity because they provide thin, foldable tissues with high epithelialization capacity to preserve local anatomy as well as chewing, phonation, and deglutition. However, there are unanswered questions regarding the epithelialization process and other histopathologic changes occurring after transfer of these flaps into the oral cavity. To investigate these changes thoroughly, an experimental study was conducted in the dog model. Bare dorsal thoracic fascia was used as the free flap model. Ten adult dogs were used in this experiment. Oral mucosa defects measuring 6 x 5 cm were created. Free dorsal thoracic fascia flaps were harvested. The vascular pedicle of the fascia flap was anastomosed with the superior thyroidal artery and external jugular vein. Then, the flaps were transferred into the mucosa defects. The dogs were divided into groups, each composed of two animals. At 7, 14, 21, 30, and 60 days postoperatively, general anesthesia was administered to the groups 1, 2, 3, 4, and 5, respectively. First, clinical assessment was performed; then specimens were obtained. Initially, the flaps were gradually infiltrated by acute inflammatory cells coming from the circulation and then replaced by granulation tissue. Epithelial cells deriving from wound margins migrated onto the granulating flaps with eventual coverage of highly organized epithelium after 4 weeks, and the fascia flap could not be differentiated from the native mucosa. The flaps were replaced by normally maturated fibrous tissue containing regular collagen fibers, instead of atypical scar tissue. Wound contraction was calculated as 18 percent at postoperative day 60. It was detected that bare free fascia flaps used in the repair of mucosa defects act as a scaffold and complete epithelialization from surrounding margins. They can be accepted as the main surgical option for the reconstruction of oral cavity mucosa defects.

Do intraoral radial forearm free flaps re-mucosalise and is candida infection relevant?

Eleven patients, with a mean age of 57 years, who had undergone radial forearm flap reconstruction following the excision of intraoral carcinoma, underwent flap biopsy at a mean of 45 months postoperatively. Seven of the patients had received postoperative radiotherapy. In eight patients the clinical appearance of the flap was similar in colour to that of adjacent normal oral mucosa; the remaining flaps retained the appearance of normal volar forearm skin. Histological examination of the flaps showed varying degrees of telangiectasia and mild chronic inflammation. In only two patients was superficial infection by candida hyphae identified. Intraoral free flaps, although clinically resembling oral mucosa, retain histological features of skin, at least within the period under study. The erythematous clinical appearance was not correlated with the presence of chronic fungal infection, but reflected the presence of vascular repair tissue, telangiectasia and mild residual chronic inflammation.