This article reviews the findings of 5 original papers in the areas of jaw function published in the Journal of the Japan Prosthodontic Society (J Japan Prosthodontic Soc; Nippon Hotetsu Shika Gakkai Zasshi in Medline/PubMed; issued in Volume 52, 2008). A variety of subjects in relation to body movement associated with mandibular movement, parameters for mandibular movement analysis, system evaluation for a new jaw tracking device and obstructive sleep apnea were examined in the listed articles.

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Purpose: The aim of this study was to compare the bonding strength, flexural strength, elastic modulus, water absorption and the expansion after water storage of new self-adhesive resin cements to commercially available dental cements.
Methods: Two types (hand-mix and auto-mix) of new self-adhesive resin cements (SAC-H and SAC-A, Kuraray Medical), one conventional resin cement (Panavia F2.0), three self-adhesive resin cements (Relyx Unicem, Maxcem and G-Cem), and two resin-modified glass-ionomer cements (Fuji Luting S and Vitremer) were used. Shear bond strengths, flexural strengths and elastic moduli (ISO 4049), water absorption (ISO 4049), and the expansion rate after water storage were investigated.
Results: Both SAC-H and SAC-A provided adhesion to enamel and dentin, and had the same bond strength to gold alloy and zirconia as conventional resin cements. SAC-H and SAC-A had greater flexural strengths (86.4–93.5 MPa) than commercial self-adhesive resin cements or glass-ionomer cements. The elastic moduli of self-adhesive and glass-ionomer cements were 5.2–7.4 GPa and 2.3–3.4 GPa, respectively. The water absorption of SAC-H and SAC-A (26.3–27.7 μg/mm³) were significantly lower than commercial self-adhesive resin cements. SAC-H and SAC-A showed significantly lower expansion rates (0.17–0.26%) than commercial self-adhesive cements and glass-ionomer cements after 4 weeks water storage.
Conclusions: It is suggested that the new self-adhesive resin cements exhibited a favorable bonding capability and mechanical properties.

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Purpose: This study aimed to examine the relationship between symptoms of dry mouth and the moisture levels in patients with maxillofacial prostheses.
Methods: Dry mouth of 30 patients with maxillofacial prostheses was examined by direct measurement of oral moisture and subjective symptoms of dry mouth were surveyed using Kakinoki's questionnaire. Oral moisture was measured five times at each of the lingual mucosa and the right and left buccal mucosa using Moisture Checker Mucus® and the mean value was calculated. Using a value of 29% as a reference, patients were classified as normal when the moisture value was 29%, or more, or with dry mouth if the value was when less than 29%.
Results: The moisture levels of the patients with subjective symptoms of dry mouth were significantly lower than those of the patients without symptoms of dry mouth at each of the lingual and buccal mucosa. The moisture level of the lingual mucosa was significantly lower than that of buccal mucosa in the group reporting subjective symptoms of dry mouth, but not in those without symptoms.
Conclusion: These results suggest that the symptom of dry mouth is corresponding to the moisture level and the moisture level of the lingual mucosa is associated with symptoms of dryness in patients with maxillofacial prosthesis.

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Purpose: The interface phenomena between anodized-hydrothermally treated commercially pure titanium (SA-treated c.p.Ti) endosseous implants and biological tissue are important in osseous wound healing. Therefore purpose of this study was to characterize the morphological, structural and chemical features of SA-treated c.p.Ti surfaces after immersion in Hanks’ balanced salt solution (HBSS).
Methods: Anodic oxide (AO) c.p.Ti and SA-treated c.p.Ti disks were immersed for 14 and 28 days in HBSS (37 °C, pH 7.4). These samples were analyzed by X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, electron probe microanalyzer, and ion chromatography.
Results: X-ray photoelectron spectroscopy and X-ray diffraction patterns were similar in each sample before and after HBSS immersion. Scanning electron microscopy performed after 28 days immersion in HBSS revealed deposits completely covering SA-treated c.p.Ti. However, deposits were not observed on AO c.p.Ti after 14 or 28 days immersion. Electron probe microanalyzer results revealed an even distribution of calcium and phosphorus on SA-treated c.p.Ti after 28 days immersion, however there was no change in AO c.p.Ti disks during all immersion periods. Ion chromatography showed increased levels of calcium and phosphorus on SA-treated c.p.Ti disks compared to AO c.p.Ti disks, after 28 days immersion.
Conclusions: The results indicate that the deposits formed on SA-treated c.p.Ti surfaces contained calcium phosphate. These deposits may be formed as a consequence of the topography and physicochemical properties of SA-treated c.p.Ti surfaces and may play a key role in osteoconduction during osseous wound healing.

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Purpose: This study aimed to measure the color change, surface roughness and flexural strength of heat-polymerized acrylic resin after its immersion in denture cleansers, simulating a 180-day use.
Methods: Thirty disk-shaped (15 mm × 4 mm) and 30 rectangular samples (65 mm × 10 mm × 3.3 mm) were prepared from heat-polymerized acrylic resin and immersed in Corega Tabs, Bony Plus, and distilled water. Color measurements (ΔE) were determined by a portable colorimeter. A surface analyzer was used to measure the roughness before and after immersion (ΔRa). The flexural strength (S) was measured using a 3-point bending test. The ΔE values were submitted to statistical analysis by the Kruskal–Wallis test, followed by Dunn's Multiple Comparisons test. The ΔRa and S values were submitted to statistical analysis by ANOVA, followed by a Student–Newman–Keuls test (α = .05).
Results: The color changes were significantly higher for the Corega Tabs than for the control group. The mean ΔE values quantified by the National Bureau of Standards (NBS) were classified as Trace (0.0–0.5). The Bony Plus group had significantly higher surface roughness than the other groups. Corega Tabs and Bony Plus groups presented lower flexural strength than the control group.
Conclusions: Although the color changes after the immersion in denture cleansers were clinically insignificant, the Corega Tabs group showed higher color differences. The Bony Plus group showed significantly increased surface roughness. Both effervescent tablets Corega Tabs and Bony Plus significantly diminished the flexural strength of the acrylic resin.

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Purpose: The purpose of this study was to evaluate the effect of differences in the retainer design on load on abutment teeth and displacement of the denture base in mandibular unilateral extension base partial removable dental prosthesis to determine the optimum design for a mechanically appropriate retainer.
Methods: Three models were used. Each incorporating a removable denture with different designs of retainer positioned. In design A, Akers clasps were positioned over the first and second premolars. In design B, embrasure clasp was positioned over the first and second premolars. In design C, rest and back-action clasps were positioned over the first and second premolars, respectively. Loading on the occlusal surface of the dentures was performed in the vertical, oblique lingual and buccal directions. Load on the abutment teeth and displacement of the denture base were determined by the three-dimensional finite element method analysis.
Results: Vertical and buccolingual load on the abutment teeth by lingual and buccal direction loading on the denture were smaller in designs B and C than in design A. However, the superioinferior and buccolingual displacement of the denture base by buccal direction loading on the denture were largest in design A. Superioinferior and buccolingual displacement of the denture base by the lingual direction loading on the denture were largest in design C.
Conclusions: Under the conditions set in this study, the stability of design A was greater than that of design B or C, but load on the abutment teeth was larger.

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Purpose: Oral sensorimotor function performs an important role in mastication. This study investigated the influence of wearing experimental palatal plates on masticatory efficiency and oral stereognostic ability (OSA), and the relationship between these two functions.
Methods: Fifteen young adults with healthy dentitions (mean age, 26.4 years) participated in this study. Masticatory efficiency was determined using a sieving method and OSA test was conducted by 12 shaped forms. These tests were performed in random order under three different conditions: control (without experimental plate), Plate-A (a horseshoe-shaped and 10 mm in width from the gingival cuff) and Plate-B (the entire palate was covered). The thickness of experimental plate was 1.5 mm. The statistical significance level was set at P < 0.05.
Results: Masticatory efficiency was significantly reduced with Plate-B, but not with Plate-A, compared with control. OSA scores were not significantly influenced by the presence of either plate. A significant positive correlation existed between masticatory efficiency and OSA score in control and with Plate-A, but not with Plate-B.
Conclusion: We suggest that wearing Plate-A had no influence on masticatory efficiency and did not disturb oral sensorimotor control of the masticatory mechanism, while wearing Plate-B reduced masticatory efficiency and might have an effect on the relationship between OSA and mastication in young dentate adults.

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Purpose: The purpose of this retrospective study was to investigate factors that affected the continuing use of RPDs and the patients’ satisfaction 5 years after delivery.
Methods: Sixty-seven patients treated with 90 RPDs delivered at the Tohoku University Hospital (Sendai, Japan) between 1996 and 2001 participated in this study. The patients were re-examined 5 years after delivery. Data were collected from clinical records and a questionnaire was used to evaluate the patients’ delivery use of the RPDs. The RPD treatment was divided into three categories labeled as ‘successful’, ‘remake’, and ‘failure’. Twelve factors that might affect the continuing use and 15 factors regarding satisfaction were evaluated. Stepwise logistic regression analysis was used to assess statistical significance.
Results: Fifty-five RPDs were regarded as successful, 21 were remake, and 14 failure. Statistically significant associations were found between the continuing use and the patient's age (P = 0.002), location of the edentulous area (P = 0.047), number of occluding pairs of teeth (P = 0.038), number of occlusal rests (P = 0.038), pain while using RPDs (P = 0.006), color of the artificial teeth (P = 0.021), and tooth shape and set-up (P = 0.022).
Conclusions: These findings suggest that the continuing use of RPDs is related to factors such as the patient's age, location of edentulous area, number of occluding pairs of teeth, and number of occlusal rests, satisfaction including pain while using RPDs, color of the artificial teeth, and tooth shape and set-up.

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Purpose: This study prospectively evaluated the clinical performance of posterior zirconium-oxide-based all-ceramic fixed partial dentures (FPDs).
Methods: Forty-two abutments of 21 Cercon FPDs were fitted in 20 patients at the Tsurumi University Dental Hospital from August 2005 to August 2006. The performance of these FPDs was evaluated using the California Dental Association (CDA) quality assessment system at baseline and at all follow-up examinations.
Results: All FPDs were examined after a mean observation period of 28.1 (±3.4) months. During the observation period, no fracturing of FPDs was seen. All of the FPDs examined were rated as satisfactory with regard to all factors at the follow-up examinations based on the CDA quality assessment criteria.
Conclusion: Within the limitations of this short-term clinical study, no core framework fractures were seen. According to the CDA criteria, 100% of the FPDs were rated as satisfactory during this observation period.

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