The goal of maxillofacial prosthetic treatment is to restore functional disorders in mastication, deglutition, speech and esthetics due to cleft lip palate, tumor, trauma and so on to the original condition. However, the functional and esthetic disorders of maxillofacial prosthetic patients differ due to the wide variety of original diseases and defect shapes, and their degrees are serious compared with those of general prosthodontic patients. In addition, when these disorders are left, they are not separate but have mutual effects on each other as after-effects, and cause mental and psychological suffering. To enjoy seeing, eating and talking together is the natural right of human beings, but it is not easy for maxillofacial prosthetic treatment to fulfill those goals of maxillofacial prosthetic patients. To optimize the results of maxillofacial prosthetic treatment and maintain the results stably for a long time, organic collaboration among related medical faculties and dentistry is essential for every stage of surgery, preoperative, operative and postoperative. Mutual recognition of fundamental items and exchange of information among related clinics are also necessary. I have been engaged in maxillofacial prosthetic treatment for thirty-nine years and describe the future prospects of maxillofacial prosthetics based on my clinical experience.
Tissue engineering research using stem cells such as iPS cells has been progressing and clinical trials of iPS cell-derived tissues for patients with Parkinsonism and retinal disease are now being conducted. In the field of dentistry too, research on regeneration using oral tissue-derived stem cells is underway all over the world. In particular, it was recently reported that mesenchymal stem cells（MSCs）, as well as their role in regenerative medicine, have the ability to heal damaged cells and tissues. Our previous study indicated that systemic administration of MSCs enhanced the healing of medication-related osteonecrosis of the jaw and the healing of soft tissue around dental implants. In addition to cells, tissue engineering requires scaffolds and bioactive factors. The present article introduces recently-released scaffolds such as carbonate apatite and octacalcium phosphate/collagen composite. The application of low-molecular compound for possible bone tissue engineering is also reported. Finally, we discuss the present state of tissue engineering in Japan.
Carbonate apatite（CO3Ap） is a main inorganic component of human bone and is resorbed and replaced with bone. We have succeeded in fabricating low crystalline CO3Ap without sintering by dissolution-precipitation reaction using calcium hydroxide as a precursor. CO3Ap showed excellent biocompatibility and faster bone formation compared to other bone substitutes（anorganic bovine bone and hydroxyapatite） in rabbit femur and dog mandible. A clinical study on the effectiveness and safety of CO3Ap granules in sinus floor augmentation was successfully concluded in 2016. CO3Ap granules were approved by the Japanese government in 2017, and launched in 2018. Furthermore, we have succeeded in developing porous CO3Ap granules and aim to use them as a scaffold for bone regenerative medicine.
Accurate evaluation of tongue dynamics and rehabilitation planning is necessary for dysphagia associated with tongue resection to improve the quality of life. Videofluoroscopic study（VF） is presently the standard procedure for dysphagia evaluation. However, it is difficult to evaluate the 3-dimensional tongue dynamics. In this study, we tried to evaluate tongue dynamics using 320-row area detector computed tomography（320-ADCT）. The subjects were two patients with tongue resection and free-flap reconstruction performed at the Oral Cancer Center of Tokyo Dental College. Evaluations were done 1 week before the operation and 1 month after the operation. On the affected side and the healthy side respectively, contact time between the tongue dorsum and palate and contact time between the tongue base and posterior pharyngeal wall were used as measurement items. As a result, regarding the measurement items, case 1 showed no difference between before and after the operation. However, case 2 showed a difference in the affected side and the healthy side before and after the operation. In conclusion, it was possible to visually and quantitatively observe the relationship between the tongue and palate, and posterior pharyngeal wall. It is suggested that 320-ADCT can be used for evaluating tongue dynamics after tongue resection.
A patient with right maxillary cancer underwent sub-total maxillectomy at the Department of Otolaryngology of our hospital in October 1985, and a dent-maxillary prosthesis for a defective jaw was fabricated at our department 5 months later. Thirty-one years later, a recurrent tumor appeared on his maxilla. He consulted our department about his unsuitable dent-maxillary prosthesis. He was severely dysarthric and was unable to ingest orally without the prosthesis. It was impossible to fabricate a new dent-maxillary prosthesis due to trismus and the presence of the recurrent tumor, so we created a splint with a small obturator（without prosthetic teeth） at first. After the splint supplied some functional recovery, artificial teeth were bonded onto this splint to fulfill his esthetic requirement. Finally, he was satisfied with the situation of his prosthesis. It is important to address the esthetic aspect of terminal-phase patients, as well as to enhance functional recovery.
A 34-year-old female patient with fibrous dysplasia of left maxilla underwent hemi-maxillectomy and reconstruction with abdominal rectus musculocutaneous free-flap. It was diagnosed that defatting of the bulky flap was needed in order to obtain space for the denture and to improve esthetics. Therefore, a surgical guide, which gave the ideal shape of the postoperative site in the maxilla, was prepared. The results of the defatting based on the surgical guide were investigated by intraoral volumetric measurement using a dental cast. The values of intraoral volume at pre-hemimaxillectomy, post-reconstruction and post-defatting with dent-maxillary prosthesis were 20.07, 15.86, and 17.24 cm3, respectively. For reconstruction with prosthesis, this procedure could be effective to maintain the intraoral space after reconstructive surgery.
A 72 year-old male underwent partial maxillectomy due to odontgenic clear cell carcinoma and suffered from difficulties in mastication, dysphagia, articulation disorders, and esthetic concerns. To restore oral functions and esthetics, a closed hollow bulb obturator was planned in the edentulous maxilla with the defect. The tissue undercut in the defect was used to engage for gaining retention and stability of the obturator prosthesis; lingualized occlusion was applied to gain optimal stability of the prosthesis. The obturator was fabricated and adjusted at regular intervals. The initial self-assessed masticatory ability of 10% increased to 50% at 1 year after delivery of the obturator prosthesis using a questionnaire designed by Sato. The oral functions and esthetics were improved by the closed hollow bulb obturator using the undercut in the defect.