Purpose: To evaluate the electromyographic activities (EMG) of masseter muscles during speech as a method for evaluating muscle fatigue in myalgia patients.
Methods: The control group consisted of 6 subjects (3 males and 3 females, mean age 25.8 yrs), and the patient group consisted of 6 myalgia patients (6 females, mean age 29.5 yrs). The bilateral EMG of the masseter muscles were recorded using bipolar surface electrodes and a computer-based EMG analyzer (UAS-108, UNIQUE MEDICAL Co. Ltd.) during the following sessions: rest (30 seconds) / speech / rest (30 seconds) / maximum voluntary contraction (MVC, 5 seconds). Integrated electromyograms (IEMGs) and mean power frequency (MPF) were subjected to statistical comparisons between the two groups with t-test and Pearson’s product moment correlation coefficient.
Results: No significant difference was found in the IEMG during speech between the two groups, while the myalgia patient group showed significantly lower IEMG than the control group during maximum voluntary contraction (MVC) (P=.004). MPF during speech was significantly higher in myalgia patients (P=.040). The same tendency was observed in MPF during MVC, although the difference was not significant. In the control group, strong correlations were found between MPFs during MVC and speech (r=.929, P=.007), and between IEMGs during MVC and speech (r=.822, P=.045). In myalgia patients, no such correlations were observed.
Conclusion: The results from this study may suggest the possibility that MPF during speech can be a method for evaluating masticatory muscle fatigue.

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Purpose: The purpose of this study was to investigate denture plaque microflora of geriatric inpatients and maxillary defect patients from the standpoint of infection control in the elderly.
Methods: Denture plaque was collected from 80 elderly subjects who were categorized into 3 groups: group A, 21 healthy complete denture wearers; group B, 49 complete denture wearers residing at a geriatric hospital; and group C, 10 complete denture wearers with maxillary defects. The microflora was investigated by counting the total number of microorganisms, including streptococci, staphylococci, and Candida spp.
Results: The colony-forming unit (CFUs) count and incidence, particularly those of Candida spp., were significantly higher in group B (P<0.01). The CFUs of staphylococci were significantly higher in group C (P<0.01), and methicillin-resistant Staphylococcus aureus (MRSA) was observed in all Staphylococcus-positive patients. The CFUs of Candida spp. were significantly correlated to those of staphylococci (P<0.01).
Conclusion: A high CFU count of Candida spp. and staphylococci (including MRSA) are characteristic of the microflora in geriatric inpatients and maxillary defect patients, respectively. This study supports the hypothesis that dentures might serve as potential reservoirs of organisms causing systemic infections.

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Purpose: The purpose of this study was to investigate the relationship between the number of splinted teeth and the effect of splinting on the movement of canines as abutments for maxillary distal-extension removable partial dentures.
Methods: A three-dimensional finite element method was used for the analysis. Abutments with normal bone height and with bone height lowered by 3 mm were prepared. The numbers of splinted teeth were two, three and six units. A load of 50 N or 200 N was applied in the vertical, buccal-oblique and lingual-oblique directions at the node corresponding to the buccolingual center of the mesial marginal ridge of the left first molar. Different material properties of the mucosa and periodontal ligament were used depending on the amount of loading. The ligament was defined as an orthotropic material.
Results: The results showed that horizontal displacement of the canine in the “two-unit splint” model was approximately one-third to one-half of that in the single abutment model. There was little difference in the horizontal displacement between the two-unit splint and “three-unit splint” models. In the “six-unit splint” model, the displacement was reduced to approximately half of that of the two-unit splint model. In all of the splinted models, the vertical displacement was reduced to approximately half of that of the single abutment model.
Conclusion: In the cases of reduced periodontal support or large and/or laterally directed occlusal force, abutments should be splinted. In cases of a coincidence of these unfavorable conditions, splinting six anterior teeth was recommended.

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Purpose: The purpose of this study was to demonstrate how a clinician’s experience might affect the complete denture treatment.
Methods: A randomized controlled parallel clinical trial at two hospitals was conducted from April 2004 to July 2006. Written informed consent was obtained from the study subjects. Permuted-block randomization was performed with a block size of 4, indicating that not only was the clinician’s experience randomized) but also the denture base materials used (conventional acrylic resin and resilient liner). The chair time required for each step of complete denture treatment was compared between the junior clinician and senior clinician groups. The clinical protocol was carried out as follows: the preliminary impression, final impression, maxillomandibular registration, trial placement, denture delivery, and the number of visits for denture adjustments. Seventy-four subjects were assigned to this trial.
Results: Significant differences were observed between the junior clinician and senior clinician groups with regard to chair time required for final impressions and the number of visits required for denture adjustments. There were no differences in chair time required for the other treatment steps.
Conclusion: This randomized controlled clinical trial revealed that a clinician’s experience has an obvious influence on the chair time required for a final impression and the number of visits for denture adjustment.

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Purpose: The aim of this study was to elucidate the features of patients with persistent uncomfortable occlusion (PUO).
Methods: Clinical states of 39 patients with PUO that was not improved by dental treatment for six months or more were retrospectively examined.
Results: In all patients, the events involved in the onset of the uncomfortable sense were dental treatments. PUO improved in 17 patients after treatment in our clinic but did not change in 22 patients. The mean periods of PUO and the mean numbers of dental clinics visited before visiting our clinic were 40.8 months and 2.3, respectively, in the improved group and 55.5 months and 3.1, respectively, in the non-improved group. However, there was no significant difference between these data in the two groups. No significant relationship was found between treatment results and age, sex, events involved in the onset of the uncomfortable sense, expressions of chief complaints, occlusal contacts and diagnosis of psychiatric disorders. There was a significant relationship between medication with muscle relaxants and treatment results. The following patterns of occlusal states were included in PUO; obvious malocclusion, malocclusion detected by strict examination, malocclusion resulting from patients’ intolerance, malocclusion not associated with patients’ complaint and no observable abnormality of occlusion.
Conclusion: The results suggested that PUO includes several patterns of occlusal states and that not all cases of PUO are morbid and incurable. It is difficult to predict the prognosis of PUO only by data concerning clinical history of PUO and occlusal contacts at the initial examination.

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Purpose: Little objective investigation has been published regarding factors influencing masticatory performance of post-maxillectomy patients with obturator prosthesis. This study aimed to assess the relationship between masticatory performance and sociological and post-surgical factors, and to develop a theoretical equation predicting masticatory performance using significant factors.
Methods: In 37 post-maxillectomy patients with obturator prosthesis, their age, gender, resection of hard and soft palate, number of posterior maxillary teeth, occlusal support, and mouth-opening distance on masticatory performance were investigated, and masticatory performance was measured using a gummy jelly. The influence of these items was evaluated quantitatively using multiple regression analysis (Quantification Method type I). The strength of influence of each explanatory factor on the masticatory performance, identified by the category weight and theoretical value of masticatory performance of each subject, was calculated by totaling the category weights and the constant. Pearson correlation coefficient was used to analyze the correlation between actual values and theoretical values of masticatory performance.
Results: The order of strength of influence on masticatory performance was identified by the category weights: extent of hard palate resection (1229.9) > occlusal support (1113.0) > mouth-opening distance (280.8) > age (209.0) > resection of soft palate (194.2) > number of posterior maxillary teeth (186.4). There was a high correlation (R²=0.863, P<0.01) between the theoretical values calculated by the predictive equation and the actual values.
Conclusion: Masticatory performance of post-maxillectomy patients could be predicted with high accuracy in patients with soft palate defect limited to the anterior part.

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Purpose: We conducted this study in order to define the methods of treatment that are beneficial for TMD patients by the comparison of the characteristics of TMD patients between prosthodontic clinic (PD-C) and special clinics for TMD (TMD-C).
Methods: Clinical records that had been preserved in a database of 253 new TMD patients treated in PD-C were compared with 404 new TMD patients treated in TMD-C. Items of sex, age, chief complaint, present observations, diagnostic categories, treatment methods and treatment outcome were investigated. The chi-square test was used for comparison of the items in two groups (StatMateIII for Windows).
Results: The TMD patients in both groups were characterized as being a high female-to-male ratio. Most symptoms were pain of TMJ and masticatory muscles as the chief complaint and present observations. According to the diagnostic categories, there were the most Type I conditions (masticatory muscle disorders) in PD-C and the most Type III conditions (disc disorders) in TMD-C. Treatment consisted of mostly splint therapy (81%) in PD-C, and patient education (67%) and physiotherapy (64%) in TMD-C. Thirty percent of the patients in PD-C and 42% of those in TMD-C were completely healed, thus showing that the treatment outcome of TMD-C was superior.
Conclusion: We reached the conclusions that the treatment outcome of TMD patients was superior, as we provided patient education such as prohibition of tooth contact and orofacial parafunctions, and physiotherapy such as jaw opening stretches. Clinicians who treat TMD patients should choose patient education and physiotherapy as their first approach.

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Purpose: The purpose of this study was to verify the usefulness of an oral appliance (OA) in patients with obstructive sleep apnea syndrome (OSAS), and to examine the relationship between the shift in mandibular position and fluctuations in the oropharyngeal space.
Methods: Fourteen patients (5 females and 9 males; mean age 51.1 years) diagnosed with OSAS were evaluated by pulse oximetry before and after insertion of the OA. Similarly, lateral cephalometric radiographs for each patient were obtained while sitting and awake in an upright position, in the intercuspal position, with the OA and at maximum opening.
Results: Using the OA, the oropharyngeal space increased significantly with the exception of the top of oropharynx. At maximum opening, the space significantly decreased in the lower part of the oropharynx, however the space in the upper part of the oropharynx was significantly increased. In the lower part of oropharynx using OA, there was a relationship between the anterior shift in mandibular position and the increase in oropharyngeal space. However, there was no significant relationship between the downward shift in mandibular position and the increase in oropharyngeal space. The oxygen desaturation index and cumulative percentage of time spent at saturations below 90 % during sleeping were significantly decreased in patients using OA.
Conclusion: These results confirm that the OA is useful as a cure for patients with OSAS and it suggests that the excessive increase in occlusal vertical dimension using the OA is of no value in expanding the oropharyngeal space.

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Patient: The patient was a 56-year-old male presenting with a missing maxillary right central incisor. Subsequently, an endosseous implant was fiited. After a 6 month healing period, a provisional abutment was fabricated to an optimal shape on the provisional titanium component. After confirming custom-guided tissue healing and appropriate emergence profile, the provisional abutment was scanned using the Procera^® scanner. The CAD/CAM custom titanium definitive abutment and the definitive porcelain fused to the metal crown were delivered as an esthetic implant restoration.
Discussion: Compared to conventional procedures, the following advantages can be seen: 1. There is no access hole in the provisional restorations. 2. Appropriate soft-tissue contours can be induced by modification of provisional restoration. 3. A definitive abutment with the identical contours can be reliably obtained using CAM. 4. An extra temporary plastic component is not necessary.
 The disadvantages are: 1. The provisional abutment using the temporary cylinder has to be made. 2. The Procera^® scanner has to be set up chair-side. 3. The patient has to wait during scanning.
Conclusion: A custom Procera^® abutment with an ideal emergence profile can be fabricated by scanning the provisional abutment with appropriate soft-tissue contours.

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