Dental Implant–Supported Prosthetic Rehabilitation With Custom Attachment in a Patient With Partial Maxillectomy Defect Because of Osteosarcoma: A Case Report

Osteosarcomas are primary malignant bone tumors in which mesenchymal cells produce osteocytes.¹  Osteosarcoma of the jaw is an unusual lesion that occurs in fewer than 4% of all patients with osteogenic sarcomas; its main clinical features are swelling, pain, and ulceration.^1–3  Radiologic findings may include radiolucency, radioopacity, or a poorly defined mixture of both.^2,3  Early diagnosis and adequate surgical resection are important to achieve high survival rates.³  Prosthetic rehabilitation procedures in postoncologic patients after bone reconstruction are similar to those in patients with severe atrophy of the upper or lower jaw after bone reconstruction.⁴  Treatment of patients with malignant neoplasia of the oral cavity requires collaboration by a team of specialists during diagnosis, treatment, and oral rehabilitation.⁵ 

The aims of prosthetic rehabilitation in maxillectomy patients are to separate the oral and nasal cavities to provide adequate articulation, to restore the contour of the midface, and to provide acceptable aesthetic results.⁶  The absence of retention and stability after obturator construction are major problems in patients undergoing maxillectomy.¹  The retention of an obturator depends on several factors, including direct and indirect retention by the remaining teeth, the size of the defect, undercutting of existing tissue around the cavity, and development of muscular control.⁶  The presence of teeth facilitates prosthetic rehabilitation; however, for many clinicians, prosthesis production remains difficult for patients who have large defects after maxillectomy.⁷  In the prosthetic rehabilitation of such patients, implants placed in the zygomatic bone can provide significant prosthesis support and retention.^8,9  This clinical case report describes prosthetic rehabilitation via placement of dental implants in the zygomatic bone in a patient who underwent partial maxillectomy caused by osteosarcoma.

A 26-year-old female patient presented to the Department of Prosthodontics, Erciyes University Faculty of Dentistry, because of retention and stabilization problems with her existing obturator. The patient had been diagnosed with osteosarcoma at the age of 15 years and had received 10 courses of chemotherapy after hemimaxillectomy. Subsequently, oral function was achieved with a dental tissue-supported obturator prosthesis. Teeth 6, 7, 8, 3, and 2 and all mandibular teeth were present in the mouth (Figure 1). Teeth 3 and 2, which had undergone endodontic treatment, were now painful. Clinical examination revealed no left hard or soft maxillary palate. Mandibular motion was within normal limits, and none of the mandibular teeth extended upward. Tongue function was normal, but the obturator fell from the patient's mouth when she spoke. The patient stated that the prosthesis was unstable, despite many adjustments and maintenance procedures. Implant placement in the patient's zygomatic bone was planned to provide retention, stability, and adequate support for a new obturator. The alveolar crest was completely absent in the left maxilla area; therefore, 2 dental implants were planned in the zygoma because a single implant would be exposed to excessive torsional force, and a large part of the implant would remain outside the bone.

Diagnostic impressions were taken of the patient's upper jaw, and cone beam computed tomography (CBCT) was performed (Newtom 5G) (Figure 2). The measurements and CBCT images were sent for planning and surgical stent production by surgical and prosthetic specialists using coDiagnosticX software (Dental Wings GMBH). Two 3.3- × 10-mm dental implants (Straumann AG) were planned for placement on the anterior side of the zygomatic bone, and a dental tissue–supported surgical stent was produced (Figures 3 and 4).

General anesthesia was induced, and nasotracheal intubation was applied. Infiltrative anesthesia was induced in the patient's zygoma and infraorbital region using 4 mL articaine (Sanofi Aventis). A mucosal incision was made, originating over the zygomatic bone and extending to the infraorbital edge. The anterior, medial, and lateral surfaces of the zygomatic bone were dissected along the incision line; dissection was carefully performed along the infraorbital margin to reveal the surgical site. The surgical stent was placed in the planned location, and its compliance was checked; it was then secured with drills and pins. In accordance with the recommendations of surgical and prosthetic specialists, implant holes were prepared by drilling, and two 3.3- × 10-mm implants (Straumann AG) were placed in the holes. The surgical stent was removed, and abutments and the longest available healing caps (6 mm) were placed on the implants. The mucosa was primarily sutured back with 3-0 Prolene sutures. Postoperative antibiotics, analgesics, and mouthwash were prescribed. Sutures were removed 1 week postoperatively.

One month after placement of the implants to the zygoma, the patient underwent retreatment of teeth 2 and 3. However, this treatment was unsuccessful, and extraction of the teeth was planned. Therefore, dental implants for teeth 3 and 5 were placed simultaneously. Buccal and palatal infiltrative anesthesia was induced with 4 mL articaine (Sanofi Aventis). Following extraction of teeth 2 and 3, osteotomies were prepared to receive 3.3- × 10-mm and 4.1- × 10-mm implants (Straumann AG) at the sites of teeth 3 and 5. The mucosa was closed with 3-0 Vicryl sutures. Postoperative antibiotics, analgesics, and mouthwash were prescribed. Sutures were removed 1 week postoperatively. The recovery period was uneventful (Figure 5).

After implant placement, although the longest available healing caps were used, they remained under the soft tissue. Pattern resin was placed around the open tray impression posts to prevent the soft tissue from sliding over the implants; the impression posts were extended and used as the base of healing during the osseointegration process (Figure 6). After a 3-month osseointegration period, obturator manufacturing was initiated. In the first session, digital measurement was attempted. However, this was unsuccessful owing to the standard size of the scan body and the presence of thick tissue over the implants in the zygoma. An open tray was prepared for the patient, and an appointment was made for functional impression.

Because of the differing axes of the implants in the zygoma and those in the region of teeth 2–4, the first measurement using an open tray impression failed. When the longest open tray impression post was used, it covered only a very small portion of the mouth; this reduced the retention of impression material by the impression post. A custom open tray impression post was then planned, with a slot through which the closed tray post fit and could be screwed tightly. Two personal impression posts were modeled and poured (Figures 7 and 8). To prevent cement leakage, the closed tray impression post was blocked with polytetrafluoroethylene (PTFE), and the prepared casting impression post was attached to the closed tray impression post with cyanoacrylate adhesive (Figure 9). The impression was taken with the custom impression post on the first attempt (Figure 10). After the model was obtained (Figure 11), a cast bar and a custom ball attachment were planned to be added to the implants in the zygoma, and a bar holder was planned to be added to the left implants.

Screw-retained abutments were placed over the dental implants in the zygoma region. The bar was modeled by placing cast copings on the screw-retained abutments, and a ball attachment was placed on the bar. Abutments were placed on dental implants in the region of teeth 2–4; cast copings and bar attachments were prepared. After the holders had been cast, they were rehearsed in the mouth, and the construction of the obturator's metal substructure began (Figures 12 and 13). After the substructure had been rehearsed in the mouth, vertical and horizontal recordings were taken, and tooth color was selected with the patient; the substructure was sent to the laboratory for tooth placement. After the teeth had been arranged, the obturator was evaluated intraorally. Dentolabial interaction, lip support, and horizontal and vertical jaw interaction were confirmed. At the end of the session, the prosthesis was delivered to the patient, along with information regarding cleaning procedures (Figures 14 and 15). The final follow-up was performed 6 months after delivery of the prosthesis. The patient was satisfied with the new obturator, and there were no signs of implant failure. Intraoral tissues appeared healthy, and the esthetics were satisfactory.

This case report describes prosthetic rehabilitation in a patient who underwent hemimaxillectomy as a treatment for osteosarcoma. Dental implants are critical in the treatment of patients who exhibit malignancies in the head and neck region. Implant rehabilitation is designed to increase patients' quality of life by providing appropriate retention for removable prostheses and reducing their burden on soft tissues.^4,10,11 

In this patient, support was received from the unaffected part of the mouth with over-implant bar holders; on the other side, support was achieved using 2 over-implant personal holders placed on the patient's zygoma, thereby avoiding soft tissue overloading. Notably, the reported survival rate for dental implants supporting maxillofacial prostheses is approximately 96.1%.¹²  The custom attachment and implanted bar holder used in this patient provided sufficient retention on the vertical axis to the obturator. The bar holder on the patient's right side exhibited greater stability than did the custom attachment; this was not surprising, because the patient's left maxilla, premaxilla, and hard and soft palate had been completely resected. Therefore, although slight anteroposterior movement was observed on the holders, this was tolerable for the patient.

Surgical reconstruction using free tissue transfer in the palate may provide a stable permanent gap between the oral and nasal cavities.^13,14  However, this method disrupts the palatal contour and prevents the obturator entering the contours of the defect for prosthesis support and ratification.^13,15  Surgically reconstructed defects may not alter the outcome of treatment compared with conventional prosthetic rehabilitation of the defect.¹⁵  The use of zygomatic implants as distant anchors has been proposed for the rehabilitation of maxillary defects, but this option was not available for the present patient because she lacked the alveolar crest because of mobility related to implant exclusion from the bone; that is, most of the zygomatic implant was located in the oral cavity and would not have any crestal support, which might have complicated the construction of the prosthesis and caused excessive torsional force on the zygomatic implants.⁹  In addition, the placement of zygomatic implants is precarious because of their proximity to delicate anatomical structures such as the orbital process, and it requires surgical experience.¹⁶ 

Rehabilitation of maxillectomy patients is challenging for both the patient and the clinician.¹⁷  Many factors, such as the length and size of the defect, number and quality of remaining teeth, and quality of available bone, contribute to optimal treatment selection for such patients.¹⁸  Another problem for patients with maxillary defects is that the prosthesis has considerable weight because of the large amount of acrylic resin required to fill the defect; hollow-bulb obturators are used to overcome this problem.^17,19  However, patients become accustomed to this weight over time. Proper diet, chlorhexidine mouthwash use, and good prosthesis care affect the long-term success of the prosthesis. For maintenance of the obturator, follow-up visits are planned every 6 months. At the 6-month follow-up, the patient in this report was satisfied with the retention and stability of the prosthesis. The bar and surrounding tissue were checked, and the bar did not need to be removed and cleaned. She noted that movement in the anteroposterior direction was increased only when she pressed her anterior teeth with her finger. The patient's prosthesis was supported in the mouth, and she was satisfied with the stability of the prosthesis when treatment was completed.

Prosthetic rehabilitation in postoncologic patients after radical maxillary resections is difficult for both physicians and patients. The correct separation of oral and nasal cavities is important in such patients. The success of obturator placement after maxillectomy requires retention by the surrounding dental tissue or dental implants. When zygomatic implants cannot be used because of the anatomical conditions, dental implants placed on the zygomatic bone and attachments fastened to these implants can easily provide the retention and stability required by the obturator.

Abbreviations

PTFE:

polytetrafluoroethylene

The authors declare no conflicts of interest.