Refabrication of an implant-retained obturator using the denture duplication technique in a bilateral maxillectomy patient with a free fibula osteocutaneous flap.

PURPOSE: 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. METHODS: 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. CONCLUSIONS: 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.

Fabrication technique of obturator-type sports mouthguard for a patient who had undergone maxillectomy and its speech intelligibility assessment:A case report.

PURPOSE: Wearing a sports mouthguard is not only recommended in collision sports, such as American football, boxing, and rugby football, but also in low-contact sports, such as basketball, handball, and soccer. It is recommended to remove oral prosthetic devices while playing sports to avoid the risk of fracturing the device. However, players with maxillectomy must wear obturator-type prosthetic devices for speech, breathing, and deglutition even while playing sports. Therefore, there is a need for an oral appliance to prevent dental injury while playing sports without the risk of fracturing the device for players who have undergone maxillectomy.In this case, we fabricated and proposed overlay-type and obturator-type customized sports mouthguards for a patient who had undergone maxillectomy and assessments of satisfaction, speech intelligibility, nasopharyngeal closure function, and swallowing function while playing soccer. RESULTS: The patient was only satisfied with the obturator-type mouthguard, and the results of the speech intelligibility, nasopharyngeal closure function, and swallowing tests using the obturator-type mouthguard showed no differences compared to those associated with the previously used prosthetic device. CONCLUSIONS: This case may help highlight the importance of providing obturator-type mouthguards for players who have undergone maxillectomy to prevent dental injury and physical and mental discomfort.

Modal analysis of two different types of fixed implant-supported prostheses embedded in edentulous maxillae.

PURPOSE: Modal analysis has been used to monitor and quantify the vibration of each component of a prosthesis at its natural frequency. An understanding of the vibrational characteristics of a prosthesis can guide selection of the appropriate prosthesis configuration to prevent excessive stress. In this study, modal analysis of fixed implant-supported prostheses with 4 or 6 abutments in edentulous maxillae was performed. METHODS: Sixteen patients underwent maxillary dental implant treatment and received screw-fixed implant-supported prostheses (9 patients received 4-abutment prostheses and 7 patients received 6-abutment prostheses) in edentulous maxillae. An impact hammer was used for excitation of the prostheses, and vibration was detected on every crown of the prostheses. The modal parameters were determined in each subject. Furthermore, the modal shapes were compared at each natural frequency. RESULTS: The median natural frequencies of subjects with 4- and 6-abutment prostheses were 697 and 781Hz, respectively. The mean damping ratios did not differ significantly between 4- (8.2±1.7%) and 6-abutment (6.6±1.7%) prostheses (p=0.125). The mean maximum displacements of fixed prostheses were significantly lower for 6-abutment (10.3±3.3µm) than for 4- (20.3±9.1µm) prostheses (p=0.004). The median number of vectors in antiphase was significantly lower for 6- (4) than for 4-abutment prostheses (14) (p=0.001). CONCLUSIONS: The current study demonstrated less adverse vibration in the 6-abutment prostheses than in the 4-abutment prostheses, suggesting that modal analysis can contribute to novel future developments in the designs of dental implant prostheses.

Factors Associated with Sleep Quality in Maxillectomy Patients.

PURPOSE: To investigate factors affecting sleep quality in maxillectomy patients after prosthetic rehabilitation and to determine the association between defect status and sleep quality. MATERIALS AND METHODS: A total of 57 patients participated in this study. Sleep quality, general health, and oral health-related quality of life (OHRQoL) were evaluated. RESULTS: Of the total sample, 89% had poor sleep quality. Early morning awakening and daytime sleepiness were the most common complaints. CONCLUSION: Defect status and the extent of neck dissection could affect sleep quality in these patients. Improvement of OHRQoL in patients with dentomaxillary prostheses may help improve sleep.

Prosthodontic Treatment of a Patient with Gnathodiaphyseal Dysplasia: 30-Year Follow-up.

This case history report describes the long-term prosthodontic treatment of a patient with gnathodiaphyseal dysplasia (GDD). The patient was initially diagnosed with osteomyelitis in the maxilla in 1986, followed by osteonecrosis spread throughout the mandible. GDD was genetically diagnosed in 2006. Despite the severe alveolar bone resorption, prosthodontic treatment improved the patient's satisfaction and ability to perform essential functions. Regular prosthesis adjustments and periodic follow-up should continue to avoid future complications.

Clinical survey over the past 35 years at the clinic for maxillofacial prosthetics Tokyo Medical and Dental University.

PURPOSE: The purpose of this survey was to examine the overview of maxillofacial prosthetic treatment at our department, in order to ascertain the actual status of patients and discuss future needs. METHODS: Subjects were all patients who visited Clinic for Maxillofacial Prosthetics, Dental Hospital, Tokyo Medical and Dental University (TMDU) in the period from January 1, 1980 to December 31, 2014. Using medical records of the Clinic for Maxillofacial Prosthetics, Dental Hospital, TMDU, patients' data including sex, address, referring institution, and primary condition were analyzed throughout the period. RESULTS: The number of patients over 35 years was 6219, with a man-to-woman ratio of 6:4. The number of patients in their 60s, 70s, and 80s showed an increasing trend. Patients with tumors accounted for about 50 % of cases in 1980-1984 and increased to 80 % in 2010-2014. CONCLUSIONS: The survey showed an increasing number of elderly patients and patients with tumors. This suggests that more awareness and education about maxillofacial prosthetics are needed.

Preschool and School Phases of Postmaxillectomy Prosthetic Rehabilitation in a Child: A Clinical Report.

This report describes the postmaxillectomy prosthetic rehabilitation of a child with maxillary chondrosarcoma over an 8-year period. Specifically, it (1) describes the planning and rehabilitation procedures carried out during the period from before the operation to the time when the patient started elementary school and (2) reports the results of evaluations of the patient's oral and psychosocial function conducted during the school phase. The prosthetic treatment plan was separated into two phases (the preschool and school phases) and was started prior to surgery, when an immediate surgical obturator was designed by the surgeons. After the operation, it was considered important to provide the patient and her mother with training regarding how the defect should be cleaned, trismus prevention, and how the prosthesis should be fitted. In addition, esthetic improvements and the ability to speak clearly were also targeted during treatment planning. After surgery, obturators were fabricated in a conventional manner and fitted at the ages of 2, 4, 6, 8, and 10 years. The patient's oral function during the use of the obturators was evaluated objectively. Marked improvements in oral function were seen during both treatment phases. The patient's ability to perform psychosocial functions at school also improved during the use of the obturators.

Sleep quality in long-term survivors of head and neck cancer: preliminary findings.

PURPOSE: This preliminary study evaluated sleep quality in long-term head and neck cancer survivors, using demographic data and clinical features of the cancers as assessment criteria. In addition, a possible correlation was examined between scores on self-rated questionnaires of sleep quality and assessments of quality of life and oral health status. METHODS: Subjects were 77 head and neck cancer survivors. Sleep quality was evaluated using the Pittsburgh Sleep Quality Index and the Epworth Sleepiness Scale. Oral and general health status was assessed using The Oral Health Impact Profile (OHIP-14) and the Short-Form Health Survey (SF-36), respectively, and correlated with clinical parameters. Spearman's correlation coefficients were calculated to examine relationships between variables. Logistic regression analysis was performed to identify independent variables associated with poor sleep quality. RESULTS: Eighty-three percent of patients had poor sleep quality (global scores ≥5) and 40% had a global Pittsburgh Sleep Quality Index score ≥8, indicating significantly poor sleep quality. Nocturnal enuresis, daytime sleepiness, and early morning awakening were the most common complaints. Extensive neck dissection, a lower SF-36 mental component score, and a higher OHIP-14 psychological disability score were independently associated with poor sleep quality. OHIP-14 global score was linked independently with daytime sleepiness. CONCLUSION: This is the first study to demonstrate a high prevalence of poor sleep quality in long-term head and neck cancer survivors. Extensive neck dissection, poor mental health, and psychological disability may contribute to poor sleep quality. Maintaining good oral health-related quality of life could promote better sleep in these patients.

Applicability of the CIELAB and CIEDE2000 Formulae for Detection of Colour Changes in Colour-Changeable Chewing Gum for Evaluating Masticatory Function.

INTRODUCTION: Mastication is one of the essential stomatognathic functions and is impaired when mandibulectomy is performed for removal of head and neck lesions. AIM: The purpose of this study was to investigate the correlation between perceived chewing ability {Masticatory Score (MS)} and objective mixing ability (∆E) in patients who had undergone marginal mandibulectomy. MATERIALS AND METHODS: Twenty normal dentate subjects as control group and twenty mandibulectomy patients who had undergone marginal mandibulectomy and wearing a dentomaxillary prosthesis were enrolled. Perceived chewing ability MS and objective ∆E were evaluated using a food intake questionnaire and the colour-changeable chewing gum, respectively. They were instructed to chew the gum continuously for 100 strokes on their usual side. The chewed gum was measured using the CIELAB colour space defined by a colourimeter and L, a* and b* were obtained. The change in colour of the gum after chewing was calculated using CIELAB (∆Eab) and the CIEDE2000 (∆E00) formula. The relationships of a*, ∆Eab, and ∆E00 with MS score were analyzed using the Spearman's rank correlation coefficient. RESULTS: A correlation was found between perceived chewing ability (MS) and objective mixing ability (index of the masticatory function {∆E}) in marginal mandibulectomy patients. (∆E00 = 0.481, a* = 0.587, ∆Eab = 0.668). CONCLUSION: Within the limitations of this study, it can be concluded that the CIEDE2000 formula for calculation of colour difference can be used to evaluate masticatory function in patients who have undergone marginal mandibulectomy.

Masticatory function and oral health-related quality of life in patients after partial maxillectomies with closed or open defects.

STATEMENT OF PROBLEM: The healing pattern after surgical resection of tumors of the oral cavity involving the maxilla may vary from one patient to another. The result may be open communication between the oral and nasal cavities (open defect) or complete oronasal separation after healing of the defect area (closed defect). PURPOSE: The purpose of this clinical study was to compare masticatory function and oral health-related quality of life (OHRQoL) between patients with closed and open defects who had undergone a partial maxillectomy and were wearing dentomaxillary prostheses. MATERIAL AND METHODS: Thirty-eight participants who had undergone a partial maxillectomy and who were wearing dentomaxillary prostheses were enrolled between September 2014 and April 2016. Participants were assigned to 2 groups according to the type of defect after healing: 19 participants had a closed defect, and 19 participants had an open defect. Masticatory function was evaluated objectively and subjectively. The objective measurement was food-mixing ability, which was assessed using color-changeable chewing gum. The subjective measurement was perceived mastication ability, rated as a masticatory score based on the patient's responses to a 35-item food intake questionnaire. OHRQoL was assessed using the Geriatric Oral Health Assessment Index (GOHAI). The GOHAI questionnaire consists of 12 items reflecting 3 hypothesized domains of the impact of oral disease: physical function, psychosocial function, and pain or discomfort. Differences in the scores obtained by the 3 measurements were compared between the 2 groups, using the Wilcoxon rank-sum test (α=.05). RESULTS: No significant differences were seen between the 2 groups in objective mixing ability, subjective masticatory score, or GOHAI (P>.05). Regarding the GOHAI physical function domain, only the swallowing item was significantly lower (P=.025) in participants with an open defect than in participants with a closed defect. Regarding the GOHAI psychological function domain, the item related to patients' psychological worries or concerns about their teeth, gingival tissue, or dentures was significantly lower (P=.045) in patients with an open defect than in those with a closed defect. Other items related to physical function, psychological function, and pain or discomfort were not significantly different (P>.05) between the 2 groups. CONCLUSIONS: The closed or open defect in patients who had undergone a partial maxillectomy may not influence patients' masticatory function and overall OHRQoL if they have adequate prosthetic rehabilitation. However, special consideration should be given to patients with an open defect with regard to swallowing function and psychological concerns in order to improve their OHRQoL.

Systematic review of literature: functional outcomes of implant-prosthetic treatment in patients with surgical resection for oral cavity tumors.

The current systematic review was performed to assess the functional outcomes of implant-prosthetic treatment on patients who have had surgical resection of oral cavity tumors. The assessment of function, satisfaction, or quality of life (QoL) were the major outcomes that evaluated preoperative and/or before and after implant-prosthetic treatment. Only eight published studies fulfilled the inclusion criteria. Three publications evaluated chewing ability, masticatory performance, and neuromuscular function, and the other five publications used questionnaire as a method of assessment. These publications mainly reported on implant-prosthetic treatment in mandibulectomy patients. It was found that implant-retained prosthesis had a beneficial effect on masticatory performance and masseter muscle activity on the defect side, but not on the non-defect side. Swallowing threshold performance and jaw movement parameters showed no significant differences between non-implant-retained prosthesis and implant-retained prosthesis. Significant improvement in prosthesis and patients' satisfaction with implant-retained prosthesis compared to non-implant-retained prosthesis was observed. However, general improvement in patients' QoL was not observed after implant-prosthetic treatment. Patients with intraoral resection might benefit from implant-retained prosthesis with regard to masticatory function and satisfaction. However, future clinical trials with an adequate sample size are needed to identify the group of patients who are likely to benefit from the implant-prosthetic treatment modality.

Association Between Masticatory Function and Oral Health-Related Quality of Life in Partial Maxillectomy Patients.

PURPOSE: The aim of this study was to investigate associations between objectively and subjectively measured masticatory function and oral health-related quality of life (OHRQoL) in partial maxillectomy patients wearing dentomaxillary prostheses. MATERIALS AND METHODS: A sample of 32 consecutively treated patients who had undergone a partial maxillectomy were enrolled. Masticatory function was assessed using two objective measures and one subjective measure. The objective measures were masticatory performance (MP), which was estimated by measuring the glucose extracted from gummy jelly, and food mixing ability (a*), which was assessed using color-changeable chewing gum. The subjective measure was perceived chewing ability, rated as masticatory score (MS) based on the patient's responses to a food intake questionnaire. OHRQoL was assessed using the Geriatric Oral Health Assessment Index (GOHAI). Relationships between the masticatory function measures and OHRQoL were analyzed using Spearman rank correlation coefficient. RESULTS: The correlation coefficients (r) obtained were 0.57 (P = .001) for MS and GOHAI, 0.247 (P = .173) for MP and GOHAI, -0.173 (P = .343) for a* and GOHAI, 0.517 (P = .002) for MP and a*, 0.199 (P = .257) for MP and MS, and 0.019 (P = .919) for a* and MS. CONCLUSION: Subjective MS showed a significant positive correlation with GOHAI score, suggesting that perceived chewing ability could be an important factor in the estimation of OHRQoL in partial maxillectomy patients.

Rehabilitation of a Bilateral Maxillectomy Patient with a Free Fibula Osteocutaneous Flap and with an Implant-Retained Obturator: A Clinical Report.

A 47-year-old man underwent surgical resection and reconstruction with a fibula osteocutaneous flap. After the surgery, a surgical obturator was placed and adjusted. After flap healing, a conventional obturator was fabricated with polymethyl methacrylate resin and retained by the anatomical undercuts around the reconstructed fibula bone flap and the posterior part of the defect. As the defect shape changed with time, a second conventional obturator was fabricated and fitted. No further recurrence of myoepithelioma was observed for 2 years, and the patient was satisfied with the obturator during mastication and speech; however, despite having no major complaints, the patient found it difficult to chew on the right side, and the obturator was displaced slightly downward when the mouth was opened wide and shifted when chewing hard and sticky food. Thus, an implant-retained obturator was suggested to provide better retention and stability. Four dental implants were therefore placed into the fibula bone, although one did not osseointegrate because either primary stability was insufficient or overload was affected in the nonloaded implant environment and was replaced. After fitting custom abutments with a magnet, an implant-retained obturator was placed, and the patient was satisfied with the outcome. During 3 years of follow-up, no issues were noted with the implant bodies, abutments, obturator, or reconstructed site. The conventional obturator was displaced slightly downward when the patient opened his mouth wide, and it shifted when chewing hard and sticky food because there was limited fibula bone at the reconstruction site and more available posteriorly. For better retention and stability, the implant-retained obturator was fabricated with a custom abutment and magnetic retention. The patient was satisfied with the results, as improved implant retention increased the stability of the prosthesis. This clinical report describes the rehabilitation of a bilateral maxillectomy patient with a free fibula osteocutaneous flap and an implant-retained obturator. The patient's oral functions were improved when the prosthesis was stabilized by means of dental implants and custom abutments.

Relationships between perceived chewing ability, objective masticatory function and oral health-related quality of life in mandibulectomy or glossectomy patients with a dento-maxillary prosthesis.

PURPOSE: This preliminary study examined whether the type of surgery performed for head and neck lesion was associated perceived chewing ability, objective masticatory function, and oral health-related quality of life (OHRQoL) in patients who required a dento-maxillary prosthesis postoperatively. METHODS: Thirty-eight patients with a dento-maxillary prosthesis were divided into three groups according to the type of surgery received: marginal mandibulectomy, segmental mandibulectomy with bony reconstruction, or glossectomy. Perceived chewing ability, objective mixing ability, and OHRQoL were evaluated using a food intake questionnaire, color-changeable chewing gum, and the Geriatric Oral Health Assessment Index (GOHAI), respectively. Differences in the scores obtained by the three measures were compared between the surgical groups using the Kruskal-Wallis test, and associations between the scores in each group were analyzed by Spearman's rank correlation analysis. RESULTS: Objective mixing ability was found to be significantly low only in patients who underwent glossectomy. No other measures differed significantly between the surgical groups. Perceived chewing ability and objective mixing ability were significantly associated in the marginal mandibulectomy and glossectomy groups but not in the segmental mandibulectomy group. Furthermore, GOHAI score was significantly associated with perceived chewing ability and objective mixing ability in the marginal mandibulectomy group. CONCLUSIONS: Within the limitations of this study, the present findings suggest that the type of surgery received might influence food mixing ability. Associations among food mixing ability, perceived chewing and OHRQoL are not accountable depending on the type of surgery received, indicating the presence of other contributing factors to be considered.

Differences of salivary cortisol levels between long-term and short-term wearers of dento-maxillary prosthesis due to head and neck cancer resection.

PURPOSE: The purpose of this study was to use cortisol awakening response (CAR) to investigate the differences in daily life stress experienced by individuals wearing either a long-term (LT) or a short-term (ST) dento-maxillary prosthesis following head and neck cancer (HNC) resection. Also we used the University of Washington Quality of Life (UW-QOL) version 4 questionnaire to evaluate the differences in quality of life (QOL) scores between ST and LT wearers of a dento-maxillary prosthesis. METHODS: Salivary samples were collected from 11 LT and 10 ST prosthesis wearers on two consecutive days at two time points, immediately after waking up (T0) and 30min later (T30), by passive drool collection. Cortisol levels were measured using a high sensitivity salivary cortisol enzyme immunoassay kit (Salimetrics, LLC, State College, PA, USA) and CAR (the differences between the cortisol levels at T0 and T30) was compared between LT and ST prosthesis wearers. In addition, both the groups completed the UW-QOL questionnaire and the scores were compared. RESULTS: A significant difference was observed in CAR between the two groups. CAR of the ST prosthesis wearers was significantly lower compared with that of the LT prosthesis wearers; moreover, the ST prosthesis wearers revealed significantly lower total UW-QOL scores and there were significant differences in appearance, activity, recreation, speech, and anxiety. CONCLUSION: Within the limitations of this study, the findings suggest that individuals wearing ST dento-maxillary prostheses following HNC resection experience some sort of daily life stress and complicated socio-demographic factors may influence their QOL.

Investigation of factor affecting health-related quality of life in head and neck cancer patients.

OBJECTIVES: 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. BACKGROUND: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Effects of a denture adhesive in edentulous patients after maxillectomy.

OBJECTIVE: The objective of this study is to evaluate the usefulness of a denture adhesive in edentulous patients after maxillectomy. BACKGROUND: Maxillectomy patients suffer from functional impairments. Denture adhesives (DAs) are the solution in such patients. However, little is known about DAs in maxillectomy patients. MATERIALS AND METHODS: Eight edentulous patients who had undergone maxillectomy were included and divided into three groups. Group 1 (half ≤ remaining residual maxilla), Group 2 (quarter < remaining residual maxilla < half) and Group 3 (remaining residual maxilla ≤ quarter). They were evaluated by a speech intelligibility test and a mixing ability test, respectively. A cream-type DA called New Poligrip(®) (GlaxoSmithKline, Tokyo, Japan) was used. RESULTS: Applying the DA, speech intelligibility showed a higher score than the data without DA. CONCLUSION: The effects of using a DA depend on the amount of the remaining residual maxilla. Our study showed that if the remaining residual maxilla is less than a quarter (Group 3), it is difficult to have confidence in the effectiveness of the DA to improve masticatory function. On the other hand, the use a DA showed improved speech intelligibility test values in all groups.

New simple evaluation method of the monosyllable /sa/ using a psychoacoustic system in maxillectomy patients.

PURPOSE: An objective assessment of speech would benefit the prosthetic rehabilitation of maxillectomy patients. This study aimed to establish a simple, objective evaluation of monosyllable /sa/ utterances in maxillectomy patients by using a psychoacoustic system typically used in industry. MATERIALS AND METHODS: This study comprised two experiments. Experiment 1 involved analysis of the psychoacoustic parameters (loudness, sharpness and roughness) in monosyllable /sa/ utterances by 18 healthy subjects (9 males, 9 females). The utterances were recorded in a sound-treated room. The coefficient of variation (CV) for each parameter was compared to identify the most suitable parameter for objective evaluation of speech. Experiment 2 involved analysis of /sa/ utterances by 18 maxillectomy patients (9 males, 9 females) with and without prosthesis, and comparisons of the psychoacoustic data between the healthy subjects and maxillectomy patients without prosthesis, between the maxillectomy patients with and without prosthesis, and between the healthy subjects and maxillectomy patients with prosthesis. RESULTS: The CV for sharpness was the lowest among the three psychoacoustic parameters in both the healthy males and females. There were significant differences in the sharpness of /sa/ between the healthy subjects and the maxillectomy patients without prosthesis (but not with prosthesis), and between the maxillectomy patients with and without prosthesis. CONCLUSION: We found that the psychoacoustic parameters typically adopted in industrial research could also be applied to evaluate the psychoacoustics of the monosyllable /sa/ utterance, and distinguished the monosyllable /sa/ in maxillectomy patients with an obturator from that without an obturator using the system.

Investigation of predictors affecting food mixing ability in mandibulectomy and/or glossectomy patients.

PURPOSE: Several previous reports have described factors that affect masticatory function. However, there are no known predictors that affect the food mixing ability of the masticatory function, and it has been impossible to predict masticatory function in mandibulectomy and/or glossectomy patients. The purpose of the present study was to develop a numerical formula that could predict the food mixing ability of the masticatory function among mandibulectomy and/or glossectomy patients. The null hypothesis of the study was that five predictors, namely mandibulectomy, mandibular continuity, number of residual mandibular teeth, occlusal units and tongue movement score, were unable to account for the mixing ability index (MAI) in mandibulectomy and/or glossectomy patients. METHODS: The subjects were 20 patients who had undergone mandibulectomy and/or glossectomy. The above-described five predictors were assessed. Tongue movement was evaluated with a tongue movement test and the MAI was evaluated with a mixing ability test. Multiple regression analysis was used to examine whether the five predictors affected the MAI after prosthetic treatment. RESULTS: A regression equation was determined for the five predictors (R(2)=0.83; adjusted R(2)=0.77; p<0.001). CONCLUSION: The obtained regression equation could successfully account for the MAI in mandibulectomy and/or glossectomy patients.