The bone defect can result from various causes, such as tumors, trauma, and infection. Oral squamous cell carcinoma (SCC) of the lower gingiva requires mandibular resection. In general, when carcinoma of the lower gingiva occurs, marginal mandibulectomy or segmental mandibulectomy can be selected. When the mandible has been invaded, the mandible is resected segmentally and then reconstructed with a soft tissue flap or complex reconstruction using hard and soft tissue free flap. Conversely, when the mandible is not involved in the carcinoma in the clinical and preoperative radiologic examination, the mandible can be treated by marginal mandibulectomy and primary closure or free flap reconstruction. For reconstruction of the mandible, it is important not only to recover the facial appearance but also to rehabilitate the dentition to restore mastication and speech. Moreover, the patients desire a complete recovery of the bony defect and fixed prosthesis. Therefore, reconstruction of bone and soft tissue and dental implant placement is considered the best treatment for esthetic and functional recovery.

Sufficient bone volume and stability of the bone are important factors for dental implant placement. However, when dental implants are placed in a patient with a severely atrophic mandible or who has had a marginal mandibulectomy, insufficient bone height and soft tissue volume may be a challenge. Vascularized bone grafts, distraction osteogenesis, non-vascularized bone grafts, and guided-bone regeneration have been used for dental implant placement for oral rehabilitation.

The purpose of this case report is to present a case of vertical and horizontal bone augmentation using three-dimensional (3D)-printed biodegradable membrane and dental implants after marginal mandibulectomy.

We followed the Helsinki Declaration throughout this study. We obtained approval from the Chosun University Institutional Review Board (CUDHIRB2103004).

A 51-year-old female patient visited with a complaint of swelling on the right retromolar gingiva and food impaction (Fig. 1). An incisional biopsy under local anesthesia was done and it was diagnosed as SCC. Computed tomography (CT) and positron emission tomography (PET) were taken to evaluate metastasis. Right mandible and ipsilateral cervical lymph nodes in level I and II with intense fluorodeoxyglucose uptake were observed.

Fig. 1. Initial examinations. (A) Intraoral photography was shown erythematous lesion on right posterior mandible. (B) Panoramic radiography.

Subplatysmal dissection and selective neck dissection was done (level I, II, III). The extraction of right mandibular second premolar, wide excision, and marginal mandibulectomy to the retromolar area including right mandibular first and second molars were performed. The lingual nerve was preserved and primary closure was done with the floor of the mouth and buccal mucosa (Fig. 2). The tumor-free margins were identified through frozen biopsy. The patient was discharged 10 days postoperatively without any complications. Follow-up observations including enhanced neck CT taking were performed every 3 months after surgery, and no additional recurrence was observed (Fig. 3).

Fig. 2. Intraoperative photography. (A) Wide resection including involved teeth, gingiva, and mandible was performed. (B) Resected mandibular segment.

Fig. 3. (A, B) Postoperative examination 3 months after surgery.

The patient used partial flexible dentures because there was not enough bone to place the implants. However, the pain and discomfort in the alveolar ridge area were severe, so implant placement had to be considered.

First of all, bone grafting had to be preceded by implant placement because there was a severe bony defect in the operation site. To secure sufficient height and width of the bone, a membrane was needed to maintain the bone volume.

The customized membrane (BellaPore PSI Plus; T&R Biofab, Siheung, Korea) was designed using Geomagic freeform software (3D systems, Valencia, SC, USA). This membrane was produced with biocompatible polycaprolactone (PCL) and β-tricalcium phosphate (β-TCP). This PCL/β-TCP membrane was fabricated in a 3D structure to fit exactly the shape of the alveolar bone (Fig. 4).

Fig. 4. Customized three-dimensional design of patient-specific membrane.

In this case, particulated cancellous bone was harvested from the left anterior iliac crest and fixed with a customized PCL/β-TCP membrane (Fig. 5).

Fig. 5. Vertical and horizontal augmentation. (A) Crestal and vertical incision was done and bony defect was exposed. (B) Cancellous bone harvested from the left anterior iliac crest. (C) Polycaprolactone/β-tricalcium phosphate membrane was placed. (D) Primary closure was done.

After eight months, three implants (OneQ; Dentis, Daegu, Korea) were placed on the mandibular second premolar (4.2×10 mm), the first molar (4.7×10 mm), and the second molar (5.2×8 mm) (Fig. 6). The primary stability was measured with Osstell Mentor™ (Osstell AB, Gothenburg, Sweden) and the implant stability quotient was 77/77, 66/85, and 66/84, respectively. After 5 months, secondary implant surgery was performed, the periotest^® values were –7.0, –6.2, and –5.5, respectively, indicating high stability. The implant prosthesis was installed and maintained without bone resorption during 25 months of follow-up (Fig. 7).

Fig. 6. Implants placement 8 months after augmentation. (A, B) Augmented bone was observed vertically and horizontally. (C, D) Three implants were placed.

Fig. 7. (A, B) The second surgery 5 months after implant placement was performed. (C, D) The implant prosthesis installed.

Reconstruction of head and neck defects following resection surgery represents a considerable challenge for oral and maxillofacial surgeons. Especially, composite bone and soft tissue defects need to be reconstructed with flaps that allow for restoring all the anatomical structures.

Consequently, a regenerative procedure for re-establishing the lost tissue and enabling prosthetic restoration, such as dental implants, is required. Vertical bone augmentation aims to restore the previous levels of bone height and is one of the most challenging surgical procedures in dentistry as it requires the formation and maintenance of extraskeletal bone. Several techniques for vertical bone augmentation [1], such as autologous block graft, distraction osteogenesis, and guided bone regeneration combined with particulate grafts, have shown varying levels of success and are generally considered to be technique sensitive and clinically unpredictable.

For the reconstruction of large defects of the jaw, various options have been considered. The use of numerous fixation pins in combination with collagen membrane and bone graft particles has been suggested previously [2]. Block bone grafts from various sources including autogenous, allogenic, and xenogenic have been utilized [3,4]. Various scaffold materials for bone tissue engineering have been studied as carriers for osteogenic stem cells or growth factors [5,6]. Non-resorbable barrier membranes made of expanded-polytetrafluoroethylene (e-PTFE), dense-PTFE, and titanium membrane have all been tried due to their superior structural stability and space maintenance [7,8]. However, all of these have disadvantages such as membrane exposure and wound dehiscence [9]. Therefore, it is necessary to develop a membrane having excellent biodegradability, biocompatibility, and tissue integration like the collagen membrane as well as good structural stability and resorption resistance.

A synthetic bioresorbable membrane using a combination of PCL and β-TCP has recently been introduced to overcome the disadvantages of existing membranes [10].

The PCL/β-TCP membrane showed increased mechanical stability and slower degradation compared to conventional collagen membranes with reliable bone regeneration [11]. Simultaneously, the PCL/β-TCP membrane degrades to allow infiltration of cell growth, which induces adequate blending and biocompatible degradation to prevent membrane exposure [12]. Since the PCL/β-TCP membrane is fabricated with 3D printing techniques, the membrane can be designed and printed as an individually customized membrane, which fits each bone defect [10]. Acquiring a perfect fit around a bone defect can result in reduced surgery time as well as the prevention of membrane exposure [13]. Thus, due to the complementary characteristic of PCL/β-TCP, the 3D printed PCL/β-TCP membrane can simultaneously show similar degradation and mechanical stability of non-resorbable membrane and no necessity for additional surgery like resorbable membranes [14].

In this case, vertical and horizontal augmentation using 3D printed PCL/β-TCP membrane was performed to restore horizontal and vertical bone defects after marginal mandibulectomy. The PCL/β-TCP membrane placed with the autogenous iliac bone did not show any complications and showed biocompatibility and stability maintaining the bone volume. The customized 3D-printed PCL/β-TCP membrane has the potential to be a predictable biomaterial that can be utilized to reconstruct bone defects of the jaw.

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2022R1I1A3063483).

The authors declare that they have no competing interests.