The use of 3D medical model data reconstructed from CT/MRI images is not realistic in doctors’ personal computers because the file size is too large. 3D model data in XVL format, which is very lightweight and highly precise, can be easily used on Web browsers and mobile devices. The data can not only be displayed, but also processed, such as adding 3D annotations and animations. It is also possible to embed the data into MS PowerPoint slides and MS Excel files. We propose new applications of 3D medical model data by using XVL.

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Autografts for defects after surgical resection improve aesthetic outcome and oral function and are expected to become a commonly used therapy for well-indicated patients. Therapy following surgery with vascularized bone grafts improves the rehabilitation of eating and articulatory function. Computed tomography （CT） is helpful for jaw defect reconstruction: CT data are used to construct three-dimensional （3D） models for surgical simulations, for preparing bending plates, and for predicting the bending position of grafting bone when using the fibula for mandibular reconstruction. The distance can be measured by three-dimensional simulation and the postoperative shape and position of the reconstructed bone can be estimated. Three-dimensional （3D） models and 3D simulations are also expected to help surgeons and prosthodontists share information as they work together to optimize the reconstruction therapy. This paper introduces a digital 3D simulation technique and discusses possible future applications of this technology.

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The analogue processes of facial prosthesis production were sorted into chronological order, and the processes to which current digital technology can be applied were determined. The digital process was compared with the conventional method. The potential of applying digital technology to enable a certain level of facial prosthesis to be produced anywhere and by anyone in as short a period of time as possible was discussed in this paper.

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The conventional facial impression can be uncomfortable for patients and the weight of the impression material can cause inaccuracy in fabricating the facial prosthesis. Furthermore, professional training or skill is required to reconstruct the missing facial curvature in detail. The material properties of silicone require refabrication of the facial prosthesis more often compared to intraoral prosthesis. Therefore, facial prostheses should be simple to fabricate, both for clinicians as well as patients.
On the other hand, 3D modeling techniques have been applied to restorative dentistry and implant prostheses. Our group has developed a novel system of fabricating facial prostheses using 3D modeling technology. Digital facial impressions enable the facial mold to be fabricated more easily. Designing of the facial prosthesis can be simplified by using CAD software. Fabricating the negative mold of the facial prosthesis is achieved by a rapid prototyping system.
Clinical application of this system encourages the patient to regain their social life and also improves their quality of life. We outline our method as well as other applications such as a system for simulating facial prosthetic treatment.

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A symposium entitled “Digital Technology in Maxillofacial Prosthetics” was held at the 29th Academic Conference of the Japanese Academy of Maxillofacial Prosthetics on June 15, 2012 in Nagoya City. The symposium is summarized by the coordinator in this paper as follows:
1. ‌Maxillofacial prosthetic treatments of good quality with reduced pain and intervention can be provided by using digital technologies.
2. Digital technologies are effective for a team approach and communicating with patients.
3. The application of digital technologies for technical education and communication is desirable.
4. Cooperation with technical experts is necessary for technological innovation.

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Eating may be difficult for individuals with maxillofacial prostheses because of bone defects and decrease of retention.
The purpose of this study was to assess qualitative nutritional changes in maxillofacial prosthesis wearers after nutritional counseling by dieticians.
Ten post-maxillectomy patients with maxillofacial prosthesis were selected for the study. Three-day food diaries with photographs were evaluated before and after two sessions of nutritional counseling. Daily nutritional adequacy was assessed using the following parameters: total energy, protein, fat, carbohydrate, dietary fiber, minerals, and vitamin C. Prosthodontic assessments were made based on masticatory performance, maximum occlusal force, and baseline mastication score. Each subject had an initial nutritional assessment followed by an individual nutritional counseling session with a dietician, based on that assessment. A second nutritional assessment was performed 1 week after the counseling session. All data were analyzed with SPSS 19.0 statistical software.
Total energy and carbohydrate intake were adequate, while protein and vitamin C intake were more than 20％ above requirements for most subjects at the initial assessment. Four individuals had excessive fat intake.
After nutritional counseling, total energy and fat intake declined significantly.
We concluded that nutritional counseling by a dietician qualitatively changed the nutritional status of maxillofacial prosthesis wearers.

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Purpose: The deflection of the record base for edentulous patients with unilateral maxillary defect was analyzed using a three-dimensional finite element method.
Method: The model consisted of a lining mucosa and a maxillary record base. The thickness of the mucosa was 3.0 mm in the residual ridge for the normal model, and then the mucosa in the anterior region was increased to 5.0 mm for the model with flabby gum. A simulated load of 5 N vertical to the occlusal plane was applied.
Results: Under the load on the inner slope of the residual ridge at the anteroposterior center of the residual arch without flabby gum, the base showed relatively even depression. However, under the same load for the condition with flabby gum, the base showed displacement in the anterior direction and intrusive displacement of the anterior portion. On the other hand, under the loading to the anteroposterior mid part of the posterior ridge for the case of flabby gum, the base showed little displacement.
Conclusion: The force on the inner slope of the residual ridge may lessen the displacement of the record base for edentulous patients with unilateral maxillary defect and more posteriorly for patients with flabby gum.

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Nasalance evaluation is often used for cleft lip and palate patients. Proper evaluation of nasalance is also necessary in maxillectomy patients, but there are some problems such as difficulty with speaking test sentences, or that the arch of the metal sound baffle does not fit the defect side. The purpose of this study was to evaluate maxillectomy patients’ speech by nasometric evaluation using monosyllable consonants as test stimuli. Seventeen patients participated in the test in which a silicon rubber impression material was used to fill the gap between the concaved face line and the arch of the metal sound baffle. The results showed significant differences in nasalance between the two conditions; that is, with and without an obturator. The results indicate the possibility of nasometric evaluation in maxillectomy patients using monosyllables as test stimuli.

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Case
The case was a 58-year-old male patient who suffered from dysphagia, organic articulation disorders, trismus, and severe nasality after surgery for hard palate cancer （rpT4bN2cM0）.
Methods
Rehabilitation for dysphagia and organic articulation disorders was achieved by a speech therapist （ST） according to the physician’s prescription. Three appliances ― （i） an interim denture, （ii） an obturator, and （iii） a nasal speaking valve （NSV） ― were fabricated during the rehabilitation period.
Functional assessments were performed ― the speech intelligibility test, the Japanese 100-monosyllable intelligibility test, a nasometer test, a repetitive saliva-swallowing test, a modified water-swallowing test ― and a questionnaire for the three appliances was administered.
Results and Discussion
With the interim denture prosthesis, the speech intelligibility score was 2 and the monosyllable intelligibility score was 32.4％. Although swallowing, nasality, and speech improved with this appliance, nasal reflux remained, and the appliance could be worn only for a limited time.
With the obturator prosthesis, the speech intelligibility score was 2 and the monosyllable intelligibility score was 39％. Swallowing, nasality, and difficulty in speech were improved. With this appliance, nasal reflux was not observed.
With the NSV, the speech intelligibility score was 2.8 and the monosyllable intelligibility score was 33.4. Although nasality and speech improved without discomfort, the patient did not use the NSV when eating. The NSV could be worn for longer periods for daily activities because of its convenience in handling. The three appliances were preferably used in different situations, i.e., the interim denture during eating at home, the obturator during eating and talking outdoors, particularly in noisy surroundings, and the NSV during speech. From this case, it is suggested that the concept of selecting rehabilitation appliances according to their purpose during daily life may be useful for improving the patient’s quality of life.

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Prosthetic treatment for a patient with a maxillary defect involves many factors such as the location and size of the defect, number of remaining teeth and length of tissue undercut. Therefore, specific considerations of the prosthetic design and fabrication process are required for each case. This case report describes the fabrication of a sectional obturator prosthesis for a bilateral maxillary defect utilizing magnetic attachments. A 71-year-old male who had undergone bilateral maxillectomy and mandibulectomy due to florid cement-osseous dysplasia was referred to our maxillofacial prosthetic clinic. Tissue undercuts on the palatal side of the defect were planned to ensure stability of the prosthesis. Magnetic attachments were used on the right side, where a hollow-shaped obturator was divided into two segments in order to engage the undercut in function and to remove it from the mouth independently. The left-side obturator was also fabricated in a hollow shape but was united to the palatal base of the prosthesis. Assessments of masticatory function after installation of the prosthesis revealed favorable results and the patient was satisfied. Therefore, this dento-maxillary prosthesis with bilateral obturators was successful even though relatively complicated laboratory steps were required.

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Myasthenia gravis is an autoimmune disease and may cause fatigue of the skeletal muscles and loss of muscle strength. The weakness of lingual, facial, or pharyngeal muscles may cause dysphagia. In the present case, we applied a palatal lift prosthesis with palatal augmentation to a 43-year-old female myasthenia gravis patient who had dysphagia with velopharyngeal incompetence and tongue atrophia. As a result, the dysarthria with nasality and dysphagia with residue at the hypo-pharynx were improved. In general, a palatal lift prosthesis is effective for dysarthria with velopharyngeal incompetence, while it does not improve the swallowing dysfunction. In this case, the augmented form of the polished surface of the prosthesis compensated for weak intraoral pressure. This report suggested the effectiveness and limitations of a palatal lift prosthesis with palatal augmentation for neuromuscular diseases.

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