Dental and bony changes following subtotal glossectomy for cancer: A clinical report.

The impact of tongue size and forces on surrounding tissues have been described, but clinical reports on the influence on dentoalveolar structures after glossectomy for cancer are lacking. This report describes the dental and bony changes after subtotal glossectomy for squamous cell carcinoma by comparing 3-dimensional models generated from computed tomography scans at various time points during the clinical course. Surface comparison showed lingual tipping of the teeth and areas of bone surface remodeling on the alveolar bone, basilar bone, coronoid process, and condyles. Early denture planning or splinting teeth before glossectomy could be encouraged in some patients, and clinical studies are recommended.

Maxillectomy patients' speech and performance of contemporary speaker-independent automatic speech recognition platforms in Japanese.

BACKGROUND: Automatic speech recognition (ASR) can potentially help older adults and people with disabilities reduce their dependence on others and increase their participation in society. However, maxillectomy patients with reduced speech intelligibility may encounter some problems using such technologies. OBJECTIVES: To investigate the accuracy of three commonly used ASR platforms when used by Japanese maxillectomy patients with and without their obturator placed. METHODS: Speech samples were obtained from 29 maxillectomy patients with and without their obturator and 17 healthy volunteers. The samples were input into three speaker-independent speech recognition platforms and the transcribed text was compared with the original text to calculate the syllable error rate (SER). All participants also completed a conventional speech intelligibility test to grade their speech using Taguchi's method. A comprehensive articulation assessment of patients without their obturator was also performed. RESULTS: Significant differences in SER were observed between healthy and maxillectomy groups. Maxillectomy patients with an obturator showed a significant negative correlation between speech intelligibility scores and SER. However, for those without an obturator, no significant correlations were observed. Furthermore, for maxillectomy patients without an obturator, significant differences were found between syllables grouped by vowels. Syllables containing /i/, /u/ and /e/ exhibited higher error rates compared to those containing /a/ and /o/. Additionally, significant differences were observed when syllables were grouped by consonant place of articulation and manner of articulation. CONCLUSION: The three platforms performed well for healthy volunteers and maxillectomy patients with their obturator, but the SER for maxillectomy patients without their obturator was high, rendering the platforms unusable. System improvement is needed to increase accuracy for maxillectomy patients.

CAD-CAM for removable partial denture fabrication after marginal mandibulectomy based on a well-adjusted pre-existing denture.

This clinical report summarizes a workflow that introduces two approaches for fabricating a metal framework removable partial denture for a marginal mandibulectomy patient. First, the pre-existing denture was adjusted according to the piezographic technique to determine the optimal configuration for adhering to the available denture space. Second, computer-aided design-computer-aided manufacturing (CAD-CAM) technology was used to fabricate a new removable partial denture by digitally scanning the oral condition and the well-adjusted denture and then using the obtained data to design and fabricate the new denture. These two approaches can help to reduce chair time not only for maxillofacial prosthetic treatment but also for other denture cases.

Advancing maxillofacial prosthodontics by using pre-trained convolutional neural networks: Image-based classification of the maxilla.

PURPOSE: The study aimed to compare the performance of four pre-trained convolutional neural networks in recognizing seven distinct prosthodontic scenarios involving the maxilla, as a preliminary step in developing an artificial intelligence (AI)-powered prosthesis design system. MATERIALS AND METHODS: Seven distinct classes, including cleft palate, dentulous maxillectomy, edentulous maxillectomy, reconstructed maxillectomy, completely dentulous, partially edentulous, and completely edentulous, were considered for recognition. Utilizing transfer learning and fine-tuned hyperparameters, four AI models (VGG16, Inception-ResNet-V2, DenseNet-201, and Xception) were employed. The dataset, consisting of 3541 preprocessed intraoral occlusal images, was divided into training, validation, and test sets. Model performance metrics encompassed accuracy, precision, recall, F1 score, area under the receiver operating characteristic curve (AUC), and confusion matrix. RESULTS: VGG16, Inception-ResNet-V2, DenseNet-201, and Xception demonstrated comparable performance, with maximum test accuracies of 0.92, 0.90, 0.94, and 0.95, respectively. Xception and DenseNet-201 slightly outperformed the other models, particularly compared with InceptionResNet-V2. Precision, recall, and F1 scores exceeded 90% for most classes in Xception and DenseNet-201 and the average AUC values for all models ranged between 0.98 and 1.00. CONCLUSIONS: While DenseNet-201 and Xception demonstrated superior performance, all models consistently achieved diagnostic accuracy exceeding 90%, highlighting their potential in dental image analysis. This AI application could help work assignments based on difficulty levels and enable the development of an automated diagnosis system at patient admission. It also facilitates prosthesis designing by integrating necessary prosthesis morphology, oral function, and treatment difficulty. Furthermore, it tackles dataset size challenges in model optimization, providing valuable insights for future research.

Factors Related to Masticatory Rhythm in Patients with Oral Tumors.

Background: Older adults who have undergone surgery for oral tumors are at increased risk of impaired masticatory rhythm. This study investigated the correlations between masticatory rhythm, objective masticatory performance, and subjective masticatory performance as well as factors related to masticatory rhythm. Methods: The participants were 44 adults (24 men, 20 women; age range 42~90 years old) who had undergone maxillectomy, mandibulectomy, or glossectomy and were rehabilitated with a maxillofacial prosthesis. The number of functional contact teeth pairs was confirmed by intraoral examination. Chewing rate, cycle duration, coefficient of variation (CV) for cycle duration (reflecting the stability of masticatory rhythm), and mixing ability were measured simultaneously using a mastication movement rhythm tracking device during gum chewing. Maximum occlusal force was measured using the dental prescale system. Patients' perception of chewing ability was rated using a questionnaire. Results: The Spearman's rank correlation test revealed that mixing ability, patient-rated masticatory scores, cycle duration, CV for cycle duration, and maximum occlusal force showed significant correlations with chewing rate. Multiple linear regression analysis identified mixing ability and the CV for cycle duration as significant predictors of masticatory rhythm. Conclusions: Factors associated with a faster chewing rate were higher mixing ability and masticatory scores, greater maximum occlusal force, shorter cycle duration, and smaller CV for cycle duration. Stable masticatory rhythm and mixing ability are significant predictors of chewing rate. Poor masticatory performance and unstable masticatory rhythm can result in slower chewing and thus a higher risk of inadequate dietary intake.

Predicting maximum occlusal force and tongue pressure using decision tree analysis in patients diagnosed with head and neck tumors.

STATEMENT OF PROBLEM: Preserving and restoring oral functions, especially mastication and swallowing, is important to the quality of life of patients being treated for head and neck tumors. Studies that help predict maximum occlusal force and tongue pressure during prosthetic treatment, necessary for providing comprehensive, appropriate treatment and encouraging patient adherence and confidence are lacking. PURPOSE: The purpose of this clinical study was to develop a decision tree model for predicting maximum occlusal force and tongue pressure in patients diagnosed with head and neck tumors that could help both experienced and less experienced prosthodontists and oral surgeons optimize the treatment plan and support patient compliance and their quality of life. MATERIAL AND METHODS: A total of 80 patients who had been treated for head and neck tumors were enrolled in the study. Their maximum occlusal force was measured using a pressure-sensitive film and tongue pressure using a tongue pressure measurement device. Data, including basic characteristics, were transferred to a comma separated values file, which was then imported into a statistical software package to produce a decision tree. The classification and regression tree method was used to construct a predictive model. RESULTS: The number of occlusal contacts associated with not wearing a prosthesis, flap reconstruction, radiotherapy, chemotherapy, the number of teeth present, age, tumor stage, and tumor type were found to be associated with maximum occlusal force, with a prediction accuracy of 96.3%, area under the receiver operating characteristic curve of 0.99, sensitivity of 97%, and specificity of 94%. The number of occlusal contacts associated with wearing and not wearing a prosthesis, tumor stage, age, radiotherapy, and surgery type were found to be associated with tongue pressure, with a prediction accuracy of 96.3%, area under the receiver operating characteristic curve of 0.97, sensitivity of 97%, and specificity of 93%. CONCLUSIONS: The decision tree model can be an effective tool for the prediction of maximum occlusal force and tongue pressure in patients diagnosed with head and neck tumors, helping both experienced and less experienced prosthodontists and oral surgeons to provide early, appropriate, and necessary treatment before starting prosthetic treatment and helping patients with treatment compliance and communication with medical staff.

Machine Learning Prediction of Tongue Pressure in Elderly Patients with Head and Neck Tumor: A Cross-Sectional Study.

Background: This investigation sought to cross validate the predictors of tongue pressure recovery in elderly patients' post-treatment for head and neck tumors, leveraging advanced machine learning techniques. Methods: By employing logistic regression, support vector regression, random forest, and extreme gradient boosting, the study analyzed an array of variables including patient demographics, surgery types, dental health status, and age, drawn from comprehensive medical records and direct tongue pressure assessments. Results: Among the models, logistic regression emerged as the most effective, demonstrating an accuracy of 0.630 [95% confidence interval (CI): 0.370-0.778], F1 score of 0.688 [95% confidence interval (CI): 0.435-0.853], precision of 0.611 [95% confidence interval (CI): 0.313-0.801], recall of 0.786 [95% confidence interval (CI): 0.413-0.938] and an area under the receiver operating characteristic curve of 0.626 [95% confidence interval (CI): 0.409-0.806]. This model distinctly highlighted the significance of glossectomy (p = 0.039), the presence of functional teeth (p = 0.043), and the patient's age (p = 0.044) as pivotal factors influencing tongue pressure, setting the threshold for statistical significance at p < 0.05. Conclusions: The analysis underscored the critical role of glossectomy, the presence of functional natural teeth, and age as determinants of tongue pressure in logistics regression, with the presence of natural teeth and the tumor site located in the tongue consistently emerging as the key predictors across all computational models employed in this study.

Frequently used extraoral maxillofacial prosthetic materials and their longevity - A comprehensive review.

The longevity of an extraoral prosthesis depends on its physical and mechanical properties and user maintenance. Faced with multiple outcome measures, researchers find it difficult to determine the most appropriate extraoral prosthetic material. This comprehensive review evaluates the most used extraoral prosthesis materials and qualitatively assesses their longevity and function. The study aims to identify and interpret the results of current updates on the factors that affect longevity and functionality. This comprehensive review summarizes and evaluates differences in the properties of commonly used extraoral maxillofacial prosthetic materials. The review was planned to focus on all factors related to the longevity and function of the extraoral maxillofacial prosthetics. An electronic search covered English articles in PubMed, Scopus, Google Scholar, Web of Science, and grey literature. Manual searching was also performed. Six authors participated in the screening. Search engines extracted 1107 records, and 88 studies were included for qualitative and bias assessments. Silicones are the most frequently used extraoral maxillofacial prosthetic materials. Heat-cured silicones are more color-stable than those cured at room temperature. Additional ingredients and processing techniques affect prosthesis longevity.

Assessment of the color stability of two silicone elastomers for maxillofacial prostheses upon exposure to cold beverages.

PURPOSE: This study investigated the color stability of different commercially available silicone materials for facial prostheses upon exposure to everyday beverages. It was hypothesized that the beverages would not alter the color of the silicone under conditions simulating daily exposure. METHODS: Sixty specimens were fabricated using two materials - VST-50 and Silfy - and exposed to commercially available cold mineral water, tea, or coffee. Specimen color was evaluated on days 1 and 15. The color was measured with a spectrophotometer based on CIELab system and color differences were calculated as ΔE. Statistical analysis was performed using the Kruskal-Wallis test and Mann-Whitney U test. RESULTS: The mean ΔE values after 15 days of exposure to mineral water, cold green tea, and coffee were 1.016, 3.480, and 3.636 for VST-50 and 0.440, 0.798, and 1.425 for Silfy, respectively. Both materials showed significant differences in color, and VST-50 showed a greater color change than Silfy, especially for coffee. CONCLUSION: Pigmented silicone elastomers have low color stability, leading to an overall color change in silicone prostheses when exposed to pigmented beverages. Color changes in such prostheses can be mitigated by selecting materials with better color stability to extend their longevity.

Time-study research on maxillofacial prosthetic treatment.

Unreasonable medical fees can cause problems such as increased medical costs, greater medical disparities, decreased medical standards, and physician shortages. To prevent such problems, it is important to set appropriate medical fees, ensure their proper use, and improve the efficiency of medical care. The treatment of patients with maxillofacial defects is generally more expensive compared with general prosthodontic treatment because it involves more materials and requires more frequently follow-ups for longer period. However, the actual time required for maxillofacial prosthetic treatment is unclear. Therefore, in this study, we aimed to clarify the amount of time spent treating maxillofacial prosthetic patients. We analyzed clinical data from patients undergoing routine maxillofacial prosthetic treatment, irrespective of difficulty level, at 8 university hospitals and 2 dental clinics. We also collected data from maxillofacial prosthodontists on the treatment time required for various Japanese health insurance items, including the fabrication of maxillofacial prostheses. The results revealed that some aspects of maxillofacial prosthetic treatment may take longer to perform and are more costly to perform than previously thought, suggesting the need for some adjustments to the health insurance reimbursement system. Maintaining an appropriate balance between expenditures and fees will greatly benefit patients and physicians, ensuring positive health outcomes and a healthy society.

Evaluation of the color stability of three maxillofacial silicone materials after exposure to beverages: An in vitro study.

Purpose: Oral cancer often requires treatments like surgical intervention, involving surgical resection of lips and other facial parts. For those patients, prosthetic rehabilitation following surgery promotes social reintegration. This study explores the color stability of various commercially available silicone materials for facial prostheses when exposed to everyday beverages like coffee and tea. The hypothesis is that these beverages can induce color changes in silicones, simulating conditions of daily use. Material and methods: A total of 90 specimens were fabricated. There were 30 specimens deefor each of 3 nonpigmented silicone elastomers: Silfy, A-2186-F and VST-50 and were immersed in tea or coffee at drinking temperature and evaluated for color changes at time points of 0 h, 1 h, and 6 h. The color was measured with a colorimeter that used the CIE L*a*b* system and the color change ΔΕ was calculated to quantify the color change. Statistical analysis was performed by using the Kruskal-Wallis test, the Mann-Whitney U test, and the Wilcoxon signed-rank Test. The threshold for statistical significance was P < .05. Results: Color change was observed for each of the silicones exposed to the beverages (P < .05). The value of ΔE was significantly higher for A-2186-F compared with VST-50 and Silfy (P < .05 in all beverages at 6 h). The color of the elastomers progressively changed while immersed in the beverages over 6 h. The change in color was significantly greater for coffee compared with tea (P < .05). Conclusions: The color stability of nonpigmented silicone elastomers is inherently low, which contributes to the overall color change of silicone prostheses when they are exposed to beverages that contain pigments. The elastomer A-2186-F had greatest values of ΔE among the materials tested. Color changes of silicone prostheses can be lessened by selecting materials with consideration of color stability to improve their longevity and extend their period of use.

Digital design of open hollow obturator framework using existing dentures: A dental technique.

Computer-aided design and computer-aided manufacturing technology has been applied to the fabrication of maxillary obturator frameworks, both directly and indirectly. However, with earlier techniques, it was not possible to accurately determine the position of the framework conforming to the palate, an issue that has been resolved in current fabrication methods. Using the patient's existing denture, prosthodontists can determine where the framework should be positioned in the defect area. This allows the obturator bulb to be hollowed, thereby reducing weight and making adjustment easier. The most appropriate position for the finish line can be determined by accurately establishing the arrangement of the artificial teeth as well as the most appropriate polishing surface morphology. In maxillofacial prosthetics, restoring proper articulation and the swallowing function through rehabilitation is important, and determining the proper palatal morphology enables good tongue movement and facilitates the restoration of adequate function. The lighter weight contributes to protecting the remaining teeth and improves patient comfort.

An integration protocol for aligning intraoral scans to facial scans using the nasal geometry reference in a fully dentate patient.

Advanced digital technologies have rapidly been integrated into prosthodontics to improve the digital workflow for prosthetic rehabilitation. The integration of 3D datasets acquired from various imaging sources such as intraoral scanners and facial optical scanners allows the creation of virtual patients to perform presurgical simulation and prosthetic rehabilitation. The presented technique introduced a straightforward protocol for aligning intraoral scans (Trios 4, 3Shape) to optical face scans (Face Hunter, Zirkonzahn) using a global best-fit algorithm of 3D evaluation software (GOM Inspect). Nasal geometry data were used as the matching reference to produce virtual dental patients. This integration protocol ensured that the intraoral scanner (Trios 4, 3Shape) was used not only to scan dental arches but also used effectively to scan the nose. These scans along with professional facial scans can be successfully aligned to produce virtual dental patients. As only a single fully dentate patient case with an alignment deviation of 243.6 µm was used, further research to evaluate the accuracy of this protocol is needed.

Case report of a patient with mandibulectomy followed up for 11 years.

Mandibular deviation and rotation following mandibulectomy can significantly impact oral function and quality of life. The postoperative course of a 57-year-old patient who underwent mandibulectomy for oral cancer and findings over 11 years of follow-up observation to monitor changes in the mandibular position are described here. Based on the observations, it is important to raise awareness regarding the necessity of continued monitoring of mandible position and regular adjustments of prostheses for patients who have undergone mandibulectomy.

Creating and analyzing digital scans of a mandibulectomy cast with simulated trismus.

STATEMENT OF PROBLEM: Trismus associated with maxillofacial defects resulting from tumor resection or radiotherapy can make dental treatment uncomfortable for patients. Using an intraoral scanner instead of making a conventional impression could help to make prosthetic rehabilitation more comfortable. However, limited information is available regarding the feasibility and accuracy of intraoral scanners for scanning mandibular defects. PURPOSE: The purpose of this in vitro study was to evaluate the feasibility and accuracy of using an intraoral scanner to digitize a cast of a mandibular defect under various simulated trismus conditions. MATERIAL AND METHODS: An intraoral scanner was used to scan the mandibular cast under different simulated degrees of trismus (mouth opening 10, 20, and 30 mm) and nontrismus (mouth opening 40 mm). The surface areas captured were compared. The datasets were loaded into a 3-dimensional (3D) evaluation software program and then superimposed for precision analysis and on reference data for trueness analysis. One-way analysis of variance was used to compare surface area captured, precision, and trueness of the measurement under the different mouth opening conditions (α=.05). RESULTS: The surface area for which 3D data were obtained by the intraoral scanner ranged from 3199.1 to 6161.6 mm2. The area differed significantly under all mouth opening conditions (P=.001), with a smaller scanned surface area captured in severe trismus (10 mm). Precision ranged from 0.032 to 0.056 mm, and trueness from 0.037 to 0.076 mm. No significant differences were seen in precision (P=.312), but significant differences were seen in trueness (P=.016) under all trismus conditions. CONCLUSIONS: Using an intraoral scanner appears feasible for digitizing mandibular defect casts with simulated mild and moderate trismus. The accuracy of the obtained data was clinically acceptable.

Applications and performance of artificial intelligence models in removable prosthodontics: A literature review.

PURPOSE: In this narrative review, we present the current applications and performances of artificial intelligence (AI) models in different phases of the removable prosthodontic workflow and related research topics. STUDY SELECTION: A literature search was conducted using PubMed, Scopus, Web of Science, and Google Scholar databases between January 2010 and January 2023. Search terms related to AI were combined with terms related to removable prosthodontics. Articles reporting the structure and performance of the developed AI model were selected for this literature review. RESULTS: A total of 15 articles were relevant to the application of AI in removable prosthodontics, including maxillofacial prosthetics. These applications included the design of removable partial dentures, classification of partially edentulous arches, functional evaluation and outcome prediction in complete denture treatment, early prosthetic management of patients with cleft lip and palate, coloration of maxillofacial prostheses, and prediction of the material properties of denture teeth. Various AI models with reliable prediction accuracy have been developed using supervised learning. CONCLUSIONS: The current applications of AI in removable prosthodontics exhibit significant potential for improving the prosthodontic workflow, with high accuracy levels reported in most of the reviewed studies. However, the focus has been predominantly on the diagnostic phase, with few studies addressing treatment planning and implementation. Because the number of AI-related studies in removable prosthodontics is limited, more models targeting different prosthodontic disciplines are required.

Combined digital-conventional workflow to fabricate a definitive obturator from an interim obturator for a patient with an anterior maxillectomy defect.

An existing interim obturator can be reproduced as the definitive one using digital technology, with benefits for a patient with a maxillectomy. By digitally scanning the oral condition and the existing interim obturator, a definitive obturator, including a computer-aided designed and computer-aided manufactured metal framework, was fabricated and delivered to a patient with an anterior maxillectomy defect by following a combined digital and conventional workflow. This technique can hasten the adaptation of the patient to the new obturator and ensure a more comfortable and safer clinical procedure.

Use of digital technology in prosthesis fabrication for an elderly patient with a maxillectomy and severe trismus: A clinical report.

This clinical report describes a novel approach based on digital technology to fabricate a maxillofacial prosthesis for a 90-year-old woman with severe trismus who had undergone maxillectomy on the right side. The approach was safe, rapid, and less burdensome on this elderly patient, and the storage and communication of intraoral and maxillofacial prosthesis data without temporal and spatial constraints was helpful. A combination of digital and analog technology provided a maxillofacial prosthesis that improved the quality of life of this elderly patient with head and neck cancer and severe trismus.

Detailed speech evaluation including formant 3 analysis and voice visualization in maxillofacial rehabilitation: A clinical report.

Objective speech evaluation such as analysis of formants 1 and 2 and nasality measurement have been used in maxillofacial rehabilitation for outcome assessment. However, in some patients, those evaluations are insufficient to assess a specific or unique problem. This report describes the use of a new speech evaluation including formant 3 analysis and voice visualization in a patient with a maxillofacial defect. The patient was a 67-year-old man who had a maxillary defect that opened to the maxillary sinus and who had an unnatural voice even when wearing an obturator. Nasality was low and the frequency of formants 1 and 2 were normal even without the obturator. However, a low frequency of formant 3 and a shifted center of voice were observed. These results indicated that the unnatural voice was related to increased resonant volume in the pharynx rather than hypernasality. This patient demonstrates that advanced speech analysis can be useful for detecting the cause of speech disorder and planning maxillofacial rehabilitation.

Prevalence of Possible Dementia in Patients with Maxillofacial Defects and Difficulty of Inserting Obturator in Maxillectomy Patients: Toward Better Provision of Supportive Care.

As society ages, it is important to understand the prevalence of dementia and the difficulties of inserting prostheses in patients with maxillofacial defects in order to clarify issues in supportive care. We screened 183 patients for dementia using the revised Hasegawa's dementia scale (HDS-R) at the Clinic for Maxillofacial prosthetics, Tokyo Medical and Dental University, and investigated age and sex differences in HDS-R score. We asked 47 of the 183 participants about the difficulty of inserting a maxillofacial obturator prosthesis and collected subjective comments, information about the prosthesis, and data from five assessments. Multiple regression analysis was used to reveal factors associated with insertion difficulty. Overall, 8.7% of the participants were judged to have possible dementia. Men were more likely than women to have possible dementia, and the risk increased with age. Of the 47 participants, 26 reported difficulty inserting their prosthesis, 12 of whom attributed it to their oral defect. Fourteen patients advised following doctor's instructions to practice insertion in order to become accustomed to it. A lower HDS-R score had a significant impact on insertion difficulty. Cognitive function and difficulty inserting maxillary obturator prostheses should be considered in the provision of continuous supportive care to patients with maxillary defects.