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Medication-related osteonecrosis of the jaw (MRONJ) can be triggered by several antiresorptive and antiangiogenic medications, including bisphosphonates (BRONJ), denosumab (DRONJ), and other agents used to treat osteoporosis and metastatic bone cancer. Prosthodontists and surgeons continue to face new challenges because of this condition. Despite the current evidence showing that extensive surgical intervention and laser surgery have the highest healing rates, surgical reconstruction is not always possible for large jaw defects requiring prosthetic reconstruction. Moreover, surgical treatment may not be an option in some patients because of other medical conditions. In these patients, MRONJ may develop into a chronic disease with limited resolution and they may seek prosthetic rehabilitation for aesthetic and functional reasons. Therefore, prosthetic intervention may be necessary for some patients with MRONJ even in the absence of a surgical defect. Denture trauma has been reported to be a risk factor for MRONJ, and few reports have discussed the prosthodontic considerations needed for patients with this condition. The aim of this review is to highlight the prosthodontic considerations that would decrease the risk of triggering MRONJ in susceptible patients.

A lingual augmentation prosthesis (LAP) is an appliance attached to the mandible to increase swallowing by extending the denture base area. It has been proven that the swallowing function improves with the insertion of an LAP assisting the palatal augmentation prosthesis (PAP). We delivered both the PAP and LAP to a patient with subtotal glossectomy who experienced saliva drooling and masticatory dysfunction. As the dead space between the reconstructed tongue and dentures decreased in both the vertical and anterior directions, his maximum tongue pressure increased, and the status of salivation and food residue improved. LAP assisted not only for saliva drooling control but also mastication.

To compare the feasibility and accuracy of using intraoral scanners to digitize a maxillary defect model simulating various trismus conditions.Four intraoral scanners were used to digitize a maxillary defect model simulating four different degrees of trismus (mouth opening = 10, 20, 30, and 40 mm), and the scanned areas were compared. The scans were also superimposed on each other for precision analysis and on reference data for trueness analysis using 3D evaluation software. Two-way ANOVA was used to compare area, precision, and trueness among scanners and among conditions.The surface area for which 3D data were obtained by the intraoral scanners ranged from 2,672 to 6,613 mmAlthough trueness and precision differed between intraoral scanners, digitization of the maxillectomy model simulating various trismus conditions appears to be feasible from the perspective of accuracy with all of the scanners used. The smaller scanned surface area in the severe trismus condition was due to lack of data on the defect site in that condition.

Facial prostheses are often fabricated for cosmetic and psychological reasons for patients with facial defects after tumor resection. Each case is unique, and fabricating a facial prosthesis that is tailored to the individual patient requires use of specific materials and a degree of flexibility. This article describes a facial prosthesis that was made using an Adams clasp and acrylic resin for an elderly patient with metal exposure after mandibulectomy.

The purpose of this study was to evaluate the impact of the rescanning of mesh holes of different diameters on the accuracy of an intraoral scanner (IOS) used to digitize an ear model.An ear model was digitized using an intraoral scanner (Medit i500) to obtain a reference mesh. A baseline experimental scan was created by editing a duplicate of the reference mesh using the cut-out tool of the IOS software. Three equal groups were created based on the diameter of the cut-out areas: 2 mm (G1), 5 mm (G2), and 8 mm (G3) (n = 15). The cut-out areas were rescanned and a total of 45 digital files were exported. The discrepancy between the reference and the experimental digital scans was measured using the root mean square calculation (RMS). The data were analyzed by a Kruskal-Wallis test followed by a post hoc Dunn's test with Bonferroni correction.The trueness values ranged from 19.53 to 27.13 µm. There were significant differences in the RMS error values among the groups tested (p0.001) and post hoc multiple comparisons showed significant differences between the G1 and G2 groups (p = 0.04), G1 and G3 groups (p0.001), and G2 and G3 groups (p = 0.004). Overall, the precision values ranged from 4.93 to 7.73 µm and significant differences in the RMS values were only found between the G1 and G2 groups (p = 0.014).Mesh hole rescanning affected the scanning accuracy (trueness and precision) of the IOS tested. The larger the diameter of the mesh holes, the less the trueness of the IOS tested. The precision values seemed to be less affected compared with the trueness by the cut-out and rescanning procedures.

After maxillofacial surgery, some patients have not only articulation disorder, but also voice disorder. It is important for prosthodontists to know what kind of speech disorder patients have so that they can plan and implement rehabilitation. This report describes the case of a 58-year-old man with a speech disorder that developed after mandibulectomy, maxillectomy, neck dissection, and reconstructive surgery because of tumor. Objective evaluation of voice and articulation clarified that the postoperative speech disorder was due to not hypernasality but hoarseness. Conventional postoperative prosthodontic rehabilitation was performed using a delayed surgical obturator and definitive obturator and his voice was objectively analyzed at each stage. The voice disorder improved over time and the results of the voice evaluation helped the prosthodontist to further plan and implement postoperative prosthodontic rehabilitation. (Int J Maxillofac Prosthetics 2021;4:43-46)

We aimed to introduce a simple method for refabrication of an implant-retained obturator using the denture duplication technique while retaining the custom abutments for a patient who underwent bilateral maxillectomy and reconstruction with a free fibula osteocutaneous flap. We have proposed this technique to facilitate the impression-making procedure for this extensive maxillary defect and to avoid lengthy and complicated laboratory procedures.A custom tray was developed by duplicating the fitting surface of an old obturator using silicone putty. The tray was used for a bite-pressure impression wherein both definitive impression and jaw relation were obtained simultaneously, reducing the time required for the placement of a new obturator.We used the denture duplication technique to refabricate an implant-retained obturator while retaining the custom abutments. Decreased chairside time, fewer visits, the use of easily available materials, and uncomplicated laboratory procedures make this technique more economical and acceptable for patients. Using this approach, the patient was able to use the old prosthesis until the delivery of the new prosthesis. The replacement obturator that was developed using this method maintained an acceptable level of oral function.

症例の概要：初診時54歳女性，悪性腫瘍に伴う左側上顎骨部分切除術施行．その後，2度の切除術を施行． 3回の切除術に際し，術前印象を採得し，切除術直後よりサージカルオブチュレータを装着し，早期機能回復を図った．術後経過安定後にはコバルトクロム上顎顎義歯を適用した．考察：サージカルオブチュレータを装着することで，手術直後から経口摂取，会話が可能となった．最終顎義歯には，金属床顎義歯を適用し，口腔内状態は良好に経過している．術前より補綴医が関わることは，頭頸部腫瘍患者の術後の機能回復およびQOLの向上に大きく寄与する．結論：左側上顎骨切除患者に対して金属床上顎顎義歯を適用し，機能的・審美的に長期的に良好な結果を得た．

Speech evaluation is essential to the rehabilitation of maxillectomy patients. A speech intelligibility test has been frequently used for the evaluation because of its simplicity. However, the test needs human listeners and this has been a shortcoming of the test. Thus, objective evaluation methods have been discussed. One of them is formant analysis for vowel evaluation and another is psychoacoustic analysis for consonants. In this research, to evaluate the speech in five maxillectomy patients, the F2-range was examined as formant analysis and the sharpness of /sa/ was examined as psychoacoustic analysis, in addition to the speech intelligibility test, during the fabrication process of a hollow-type obturator. The objective evaluation of patients' speech was effectively performed using those three methods. The F2-range was larger, the sharpness of /sa/ was higher and the speech intelligibility was higher when patients wore an obturator compared to when patients did not wear an obturator. The difference in speech when changing the types of obturator was not clear. The method and the findings are important for future research in this field, since speech is one of the important factors in maxillofacial rehabilitation.

Head and neck cancer (HNC) patients have profound illness of physical, social and psychological factors that affects quality of life (QOL). The purpose of this study is to investigate the factors affecting HRQL in patients with intra-oral prostheses.Some cross-sectional studies have been performed to investigate HRQL in patients with HNC, but these studies did not report in detail how factors affect the HRQL of maxillectomy and mandibulectomy and/or glossectomy patients.The University of Washington Quality of Life version 4 questionnaires (Japanese version) was administered to 50 maxillectomy and 50 mandibulectomy and/or glossectomy patients with intra-oral prostheses who were selected according to inclusion and exclusion criteria. Gathered data were statistically analyzed to investigate how a number of factors, namely, age, sex, pathologic diagnosis, neck dissection, resection size, radiotherapy and dental condition affect HRQL.In the maxillectomy patients, there were no significant differences between malignant and benign tumor in pathological diagnosis or between dentate and edentulous in dental condition. Age, sex, neck dissection and radiotherapy affected HRQL. In the mandibulectomy and/or glossectomy patients, there was no significant difference between dentate and edentulous in dental condition. Age, sex, glossectomy, neck dissection and radiotherapy affected HRQL.The factors affecting HRQL in the maxillectomy patients were different from those in the mandibulectomy and/or glossectomy patients. Though they wore stable prostheses; we were still able to show that resection size, radiotherapy and neck dissection affected HRQL.