Purpose: The objectives of this study were to determine how changes in body and head position undergoing dental treatment affect mandibular position, and to develop a set of standards for patient posture.
Methods: Mandibular position was investigated in 8 subjects with normal occlusion and not suffering any stomatognathic dysfunction. This was done by measuring the location of the tapping point on the incisal point using a Gnathohexagraph (a 3-dimensional jaw movement measurement device with 6 degrees of freedom), with the subject’s head in 4 different positions while sitting, and the body and head in 16 different positions with the subject supine, and then comparing deviation from the reference position in each of these positions. Statistical analysis of data was performed using first, repeated measures of 1-way ANOVA (α=.05), second Bonferroni’s multiple comparison test was undertaken in seated positions. In supine positions, repeated measures of 2-way ANOVA was performed, and followed by Bonferroni’s multiple comparison test was performed.
Results: The incisal point deviated significantly in the anteroposterior direction due to changes in head and body position. With the subjects seated, the incisal point tended to move backwards when the subjects were asked to lean backwards from the reference position. The incisal point tended to move forward when the subjects were asked to lean forward. With the subjects in a supine position, the incisal point was inclined backwards. The degree of backwards inclination of the incisal point tended to decline as the head position was varied from 10 degrees backwards to 20 degrees forward, regardless of the degree of backwards inclination of the body.
Conclusion: Changes in body and head posture undergoing dental treatment affect incisal point deviation.

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Purpose: Our research aimed at shedding light on the effective frequency of professional oral care for those who require nursing care from oral health specialists.
Methods: Thirty-eight residents (average age, 80.0±9.4 years) of Niigata Prefecture who required nursing care agreed to participate in our study. They were divided into 3 groups; a control group (13 persons), provided with no professional oral health care: Group A (15 persons), provided with professional oral care once or twice per month: and Group B (10 persons), provided with professional oral care 4 times per month (once a week). Three dentists investigated the general health status and oral conditions such as dental formula, gingivitis index (GI), gingival bleeding index (GBI), degree of coating of on the tongue, and the type of pneumonia-causing pathogens on the pharyngeal mucosa. Professional oral care was provided by 14 dental hygienists for 3 months.
Results: Multiple comparison tests revealed that subjects in Group B showed a statistically significant improvement in GI and GBI compared to the controls. Although there was a trend showing some improvement associated with care frequency between pre- and post-intervention, no statistically significant difference was found eventually. Further, no significant difference was found before intervention with regard to the types of pneumonia-causing pathogens on the pharyngeal mucosa. Only Group B manifested a tendency of decreasing number pathogens when compared to the pre-intervention numbers, although it was not statistically significant.
Conclusion: Considering the limited time, cost, and manpower, a frequency of 4 times per month may be the most effective, but a higher frequency is recommended to prevent inflammations of the respiratory system.

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Purpose: This study evaluated the effects of water pressure on the mechanical properties and tensile bond strength of autopolymerized resins during polymerization at room temperature using a dental pressure pot with chair-side ease of handling.
Methods: Four different autopolymerized resins (Unifast II, Unifast III, Provinice, and Miky Plus) were used. Specimens were fabricated by the brush-on technique. In the pressure group, specimens were polymerized in a dental pressure pot under 0.2 MPa water pressure at room temperature. In the non-pressure group, specimens were polymerized on bench. The 2 groups were compared for dimensional accuracy, 3-point bending, and tensile bond strength. Data were statistically analyzed by two-way analysis of variance (ANOVA) with Tukey’s multiple comparison test at a significance level of α=0.05.
Results: Two-way ANOVA indicated that both resin and pressure had significant effects on the polymerization shrinkage rate (PSR). Interaction between resin and pressure was also significant. The PSR was lower in the pressure group than in the non-pressure group. The PSRs of Unifast II and Miky Plus were greatly improved by pressure polymerization. Significant differences in flexural strength were observed between the 2 groups. The flexural strength significantly increased under pressure. No significant differences in tensile bond strength were observed between the 2 groups.
Conclusion: The dimensional accuracy and flexural strength of autopolymerized resins were significantly improved by the application of water pressure during polymerization. No significant changes in tensile bond strength were observed following pressure application at room temperature.

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Purpose: In this study, we investigated the effects of addition of high-molecular-weight sodium alginate to alginate impression materials with the aim of developing a new high-viscosity impression material.
Methods: Four experimental alginate impression materials were prepared based on a conventional material (control material) by varying the percentage of addition of high-molecular-weight sodium alginate in the range of 50% to 100%. The viscosity after mixing, setting time, recovery from deformation, strain in compression, compressive strength, and compatibility with dental stones was determined in accordance with the ISO 1563 and ANSI/ADA Specification no. 18. Results were analyzed using ANOVA and linear regression.
Results: All the experimental materials exhibited significantly higher viscosity than the control material (P<0.05). A significant and positive relationship was observed between the addition rate and the viscosity (P<0.05). In the specification tests, all the experimental materials were found to be within specification limits, and not significantly different from the corresponding values of the control material.
Conclusion: The addition of high-molecular-weight sodium alginate to an alginate impression material can be effective for increasing the viscosity of the material without deterioration of the properties of the material.

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Purpose: The aim of this questionnaire study was to survey Japanese dentists’ perceptions of risks for overeruption of unopposed molars and dentists’ attitudes to prosthetic intervention.
Methods: A clinical situation with a 42-year-old male patient who just had lost the left mandibular molars was presented. A series of questions was provided regarding what would most probably occur with the unopposed maxillary molars within a 10-year period, what treatment to propose, and indications for the proposed treatment. The questionnaire was sent to the council members of the Japanese prosthodontic society, doctors of Matsumoto Dental University, members of the Nagano and Niigata prefecture dental societies via letter, facsimile or E-mail.
Results: 887 of 1320 (67%) dentists returned completed questionnaires. The great majority believed that overeruption of the unopposed molars would occur within a 10-year period (94%). 87% of respondents wanted to perform prosthetic treatment. In contrast, a “wait-and-see” alternative was chosen by only 12%. The most commonly suggested indications for the treatments were the risk for overeruption (96%) followed by impaired masticatory function (77%) and development of TMD (73%).
Conclusion: To date, the majority of Japanese dentists seem to believe that overeruption of molars would occur after extraction of antagonists, and that prosthetic interventions are necessary to prevent possible clinical problems.

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Purpose: The purpose of this study was to compare mandibular movements in the mixing ability test with those in the masticatory performance test.
Methods: Twenty-six dentate subjects (mean age 25.3 years) performed a mixing ability test using a two-colored paraffin wax cube and a masticatory performance test using 3 g peanuts. Mandibular movements during the chewing of each test item were recorded using an opto-electronic system. Twelve parameters of mandibular movements on a mandibular incisal point were measured for each masticatory cycle. The mean from 2^nd to 5^th cycle in each parameter was employed for paired t-test.
Results: 7 of 12 parameters showed significant mean differences between the mixing ability test and the masticatory performance test. Vertical amplitude, anteroposterior amplitude, maximum closing velocity and opening angle for the mixing ability test were significantly greater than for the masticatory performance test (P<0.05). Opening duration and cycle duration for the mixing ability test were significantly longer than for the masticatory performance test (P<0.05). Envelope angle for the mixing ability test was significantly less than for the masticatory performance test (P<0.001).
Conclusion: The results of this study suggest mandibular movements in the mixing ability test are partially different from those in masticatory performance test.

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Purpose: The aim of this study was to survey the undergraduate removable partial denture (RPD) clinical program and RPD’s fabricated by students in 2006, and to identify the problems to be solved in the future.
Methods: Sixty-nine students in their final semester at Tokyo Medical and Dental University (TMDU) recorded the following preoperative data: age, gender, chief complaint, and Kennedy and Eichner classifications. The students were requested to present their treated cases and were subjected to an oral examination by the professor to determine the treatment plan and prosthetic design of denture. Additionally, the students surveyed the chewing function score and visual analogue scale (VAS) regarding esthetics and stability of RPD, and the material used for RPD frameworks was summarized.
Results: The patients included 35 men and 34 women, and their chief complaints were mostly dissatisfaction with their current dentures. More than 80% of cases were classified as Kennedy I or II, and about one-fourth were classified as Eichner B4 or C1, in which the occlusal supports could not easily be reconstructed. Chewing function score significantly improved compared to preoperative state (P<0.05) and postoperative VAS was clinically acceptable. 89% of frameworks, were cast with Co-Cr alloy in one piece and a palatal strap or bar and a lingual bar were applied in 77% of treated RPDs.
Conclusion: It is thought that our educational methods for delivery of RPDs are adequate. Since it is suggested by an objective assessment of them that they are unsatisfactory, we should deal with that problem without delay.

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Purpose: This study prospectively evaluated the clinical performance of CAD/CAM-generated In-Ceram alumina core crowns.
Methods: The GN-I system was used to fabricate the 101 In-Ceram crowns with aluminum copings placed in 39 patients. Using a modified quality assessment system developed by the California Dental Association (CDA), the crowns were evaluated at baseline and at all follow-up examinations.
Results: The mean service time of the crowns was 28.7 months. Six crowns fractured or were removed; a maxillary first molar crown and a mandibular second premolar crown fractured after 17 months and 22 months, respectively. Others were removed due to esthetic complications, endodontic therapy, root fracture, and so on. A small chip was detected in a mandibular canine crown after functioning for 6 months. After 39 months, the cumulative survival rate of the crowns was 93.9%. According to the modified CDA criteria, most crowns were rated as “satisfactory” during the observation period.
Conclusion: Despite the 2 fractures, In-Ceram Alumina crowns with copings fabricated using CAD/CAM (GN-I system) showed excellent results during the observation period.

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Purpose: Since a Piezoelectric Pulse Transducer (PPT) detects finger peripheral pulse-waves, the PPT has already been used to simply record the laryngeal upward-downward movements. However, a relation between the sensor output and movements of the pharynx, larynx, and esophagus was not clear. This study was aimed to elucidate a relation between the PPT waveforms and food bolus passage during the pharyngeal phase of swallow.
Methods: The laryngeal movements by the PPT, surface electromyography of the geniohyoideus muscle, and videofluorography were simultaneously recorded. To synchronize VF, the PPT waveforms, and EMG, we touched the neck surface lightly using a small metal ball both before and after swallowing, thereby putting marks on the VF and the waves of the PPT. Then, features in the waveform of the PPT were analyzed with a personal computer.
Results: The swallowed food bolus was stopped for a moment on the epiglottic vallecula, as observed by VF. This stop was also observed in the PPT waveform as a return to the baseline. The epiglottis returned to the original position at the end of swallowing, as can be observed by VF and by a small peak in the PPT waveform. The food bolus passage was divided into two periods on the PPT waveform: TA (transit period from the base of the tongue to the epiglottic vallecula), and TB (transit period from the epiglottic vallecula to the esophagus).
Conclusion: The PPT waveforms could detect bolus passage from the base of the tongue through the epiglottic vallecula to the esophagus.

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Patients: A 55-year-old woman with complaints of esthetic disturbance and masticatory dysfunction visited Osaka Dental University Hospital. The remaining upper teeth showed severe degradation of the coronal dentine because of caries. Additionally, the vertical stop in the molar region was lost. In the initial treatment, an overdenture was placed for urgent improvement of the chief complaint. We diagnosed the patient as having esthetic disturbance and masticatory dysfunction due to many decayed and missing teeth. Subsequently, we performed oral surgical, endodontic, and periodontal treatments of the remaining teeth based on the diagnosis. According to the patient’s request, fixed prostheses, i.e., crowns and fixed partial dentures, were selected as the final prostheses.
 On the other hand, since caries progression is possible during a long-lasting treatment, the patient’s oral environment has been monitored using a saliva test to estimate caries activity. We selected the following 4 factors as the oral environmental factors: the stimulated salivary flow rate, buffering capacity, and salivary microbial counts of mutans streptococci and lactobacilli. The first examination revealed a high-risk oral environment. However, lactobacilli counts decreased immediately after the cementing of fixed prostheses and were low-risk at recall. Other factors remained at low-risk-levels throughout the treatment period.
Discussion: To improve esthetic disturbance and masticatory dysfunction, prosthetic treatment was performed, and the progressive degradation of tooth structures due to caries was prevented. The oral environment was examined by the saliva test during therapy. After the treatment, the lactobacilli counts decreased. This is thought to be the result of removing caries and poorly fitting restorations.
Conclusion: By means of the saliva test, we confirmed the improvement in the oral environment following proper prosthetic treatment.

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