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[in Japanese]
1999 Volume 43 Issue 4 Pages
635
Published: August 10, 1999
Released on J-STAGE: August 10, 2010
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Katsuji Okuda
1999 Volume 43 Issue 4 Pages
636-639
Published: August 10, 1999
Released on J-STAGE: August 10, 2010
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There are over 300 species of bacteria forming populations of several hundred billion in the human oral cavity. Using saliva and gingival cervical fluid as their main nutrients, these bacteria create their ecological niches on tooth and denture surfaces, gingival crevices, saliva, dorsum linguae, and buccal and pharyngeal mucous, threatening oral and systemic health. It is known that primary lesions of these chronic bacterial infections secondarily cause nephritis, arthritis, and dermatitis. Further, it has been demonstrated that bacteria inhabiting the oral cavity can cause pneumonia and endocarditis and that the periodontal disease associated bacteria become causative agents for blood circulation problems and coronary heart disease. It was found that
Candida albicans and Staphylococcus species including methicillin-resistant
Staphylococcus aureus, were highly accumulated on denture surfaces.
Streptococcus pneumoniae and other opportunistic pathogens were also found in samples from elderly people requiring daily nursing care. In this article, the bases supporting the concept that oral health care, primarily mouth cleaning, including denture, is important not only to prevent oral infectious disease but also a healthy life for the elderly.
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Featuring Candida spp. and Helicobacter pylori
Tetsuo Ichikawa, Katsuhiko Hirota
1999 Volume 43 Issue 4 Pages
640-648
Published: August 10, 1999
Released on J-STAGE: August 10, 2010
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Many bacteria cover denture surfaces as denture plaque in the form of a biofilm, especially dentures of geriatric hospital inpatients. Dentures may act as a reservoir of microorganisms which cause opportunistic infection such as aspiration pneumonia. Oral health care, including denture plaque control could prevent such infection. Overviews of
Candida spp. and
Helicobacter pylori in denture plaque and the approach to denture plaque control for the prevention of systemic infection are presented in this report.
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Toshio Hosoi, Chieko Ishikawa
1999 Volume 43 Issue 4 Pages
649-658
Published: August 10, 1999
Released on J-STAGE: August 10, 2010
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The formation processes of denture plaque and denture calculus were observed by optical microscopy and transmission electron microscopy. The distribution of calcium was studied using electron probe X-ray micro analysis (EPMA). Materials were obtained from 3 volunteers who wore an acrylic resin plate for 6 hours, 3 days and 7 days, and 5 complete denture wearers who wore dentures for 5 to 10 years.
The denture pellicle was adhered to the denture surface in 6 hours, then the denture plaque was observed3 days later. The denture plaque showed thicker layers and the intermicrobial matrix was formed on the surface in 7 days. Amorphous electron dense deposits appeared in the intermicrobial substances, although no mineral crystals were observed. The lamellated substance (LS) appeared in the denture plaque of the denture patients. The initial mineral crystals of calcium phosphate appeared along the plasma membrane of microorganisms and the lamellated substance and changed into calcification and denture calculus. Consequently, mechanical cleaning and chemical washing were necessary to eliminate the denture plaque and denture calculus. Furthermore, LS of the organic matter below the denture calculus had to be removed by the chemical method.
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Takashi Nokubi, Kazunori Ikebe, Kazuhiro Mitta
1999 Volume 43 Issue 4 Pages
659-665
Published: August 10, 1999
Released on J-STAGE: August 10, 2010
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Removable dentures had great effects on general health and quality of life in the elderly. On the other hand, denture plaque has been reported to cause various diseases, not only stomatitis but also aspiration pneumonia.
The purpose of this study was to determine the actual status of denture plaque in the elderly and to point out the problem in the future.
The results were as follows:
1. About half of the independent elderly wore their dentures continuously night and day and cleaned their dentures by brush only.
2. Dependent elderly had a significantly larger amount of
C. albicans on the fitting surface of dentures than independent elderly. Among dependent elderly, denture wearers had significantly larger amount of
C. albicans on the palatal mucosa than non-denture wearers.
3. Most of the staff in a nursing home felt that their knowledge of oral and denture hygiene was insufficient and had trouble with denture cleaning.
From these results, it was concluded that it was necessary to show the actual status of denture hygiene, necessity of denture cleaning and the importance of oral care for the elderly not only to providers of elderly care but also all of the people.
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Noriyuki Morioka, Kazutoshi Furukawa, Tsukasa Shioyama
1999 Volume 43 Issue 4 Pages
666-673
Published: August 10, 1999
Released on J-STAGE: August 10, 2010
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A case report of a 33-year-old male having painful reciprocal clicking during open-close procedure diagnosed as an articular disc displacement with reduction of TMJs is presented. To keep the discs in better position in relation to the condyles, occlusal reconstruction by a prosthodontical procedure following splint therapy was conducted in the initial treatment. However, since splint therapy caused severe tooth inclination in the molar region, orthodontic treatment was done instead of prosthodontics.
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Kenji Fueki, Kazuyoshi Baba, Satoshi Akishige, Tadasu Haketa, Worawan ...
1999 Volume 43 Issue 4 Pages
674-680
Published: August 10, 1999
Released on J-STAGE: August 10, 2010
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A force based bruxism detection device, which utilizes a pair of strain gauge sensors embedded in an acrylic appliance was developed. The purpose of this study was to test this newly-developed device for bruxism detection. First, the strain gauge signals and masseter EMG were recorded simultaneously in 6 healthy volunteers who performed all of the behaviors which might occur during bruxism. Analysis involved a comparison of the duration of the bruxism detected by each method. The correlation coefficients between the duration of bruxism events detected by 2 methods were sustained clenching (r=0.97, p<0.001, n=60), rhythmic clenching (r=0.95, p<0.001, n= 60), grinding (r= 0.81, p<0.001, n=57), and tapping (r=0.75, p<0.001, n=58). Then, overnight polysomnography with a subject who was aware of bruxism was performed in order to test if the strain gauge could detect actual bruxism during sleep. The correlation coefficients between the detected duration by 2 methods resulted in 0.77 (p<0.001). This study showed that the bruxism duration detected by this device is reasonably accurate when compared with the traditional EMG method.
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Part 2: Effect of Changing Occlusal Bite Positions on the Correlation between the Medial Pterygoid Muscle and the Other Closing Muscle Activity
Yoshihiro Okabe, Minoru Ai, Tomohiko Yaka, Akira Nishiyama, Masayuki S ...
1999 Volume 43 Issue 4 Pages
681-688
Published: August 10, 1999
Released on J-STAGE: August 10, 2010
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This study was conducted to investigate the muscle activity of the medial pterygoid, the superficial masseter and the anterior temporal muscles when two bite forces (49 N and 147 N) were exerted on different teeth. The subjects were instructed to perform isometric muscle contractions on either the right or left first premolar or second molar. Simultaneously, the EMG activity of the muscles was registered using subcutaneous needle electrodes.
The results were as follows:
1. The change of the bite-point location affected the EMG activity of all the muscles. Although the occlusal bite force was altered from 49 N to 147 N, various patterns in each muscle activity at each bite location were almost consistent.
2. The largest activity was observed in the medial pterygoid and masseter muscles on the contralateral first premolar, while that of the temporal muscles was on the ipsilateral first premolar. Clenching on one first premolar compared with the other first premolar resulted in a significant increase in the activity of the working-side temporal muscle.
3. The bite-point location being changed from right second molar to various other teeth, at a 49 N bite force the right medial pterygoid muscle had a significant correlation between the right or left masseter and right temporal muscles. At a 147 N bite force the medial pterygoid muscle significantly correlated to ipsilateral masseter muscle.
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Satoshi Akishige, Masaru Yatabe, Kazuyoshi Baba, Tomohiko Yaka, Takesh ...
1999 Volume 43 Issue 4 Pages
689-697
Published: August 10, 1999
Released on J-STAGE: August 10, 2010
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To investigate the factors affecting the non-chewing side contact, the relationship among simulated non-chewing side tooth contact, jaw displacement, and masticatory muscle activity was evaluated.
Seven healthy male subjects volunteered for this study. They were asked to clench on a central bearing device, and vertical displacements of lower bilateral second molars were measured by linear variable transformers. Simultaneously, EMG activity was measured from masseter and anterior temporal muscles. Thesubjects were also asked to clench with film strips in place on unilateral premolars in order to simulate the occlusal phase of the chewing cycle. Occlusal registrations on the contralateral sides were recorded, and then the occlusal contact area was calculated for each side.
Comparison of bilateral tooth contact area and second molar displacements showed that the contact area tended to be larger on the side where larger molar displacement was found. The side difference of the contact area was significantly correlated to that of second molar displacement (Pearson's r =0.85 p= 0.01), however, not to EMG activity.
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Soichiro Okamoto, Hidenori Suzuki, Manabu Kanyama, Hikaru Arakawa, Wat ...
1999 Volume 43 Issue 4 Pages
698-705
Published: August 10, 1999
Released on J-STAGE: August 10, 2010
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The growing recognition that the quality of life (QOL) is an important outcome of dental care has created a need for a range of instruments to measure oral-health-related QOL. However, validated missing tooth specific questionnaires are not currently available to assess the impact of a missing tooth and rehabilitation modalities on oral health related QOL. Therefore, a self-administered, missing tooth specific questionnaire (51 items) was made on the basis of a well-designed QOL questionnaire (Oral Health Impact Profile). Then QOL investigation of 56 patients with this newly-developed questionnaire was conducted to evaluate the validity and reliability of this questionnaire. As a result, test-retest reliability levels of these items (2 weeks apart) were acceptably high (40/44 items by Spearman correlation: 0.42-0.82). The established validity of the questionnaire was also estimated by factorial analysis and seven subscales were identified: 1) physical function, 2) psychological state, 3) mastication and oral pain, 4) pronunciation, 5) swallowing, 6) oral cleaning, 7) aesthetics. Finally, in addition to high internal consistency of the subscales, number of missing tooth was closely related to the total oral condition related scores of this questionnaire. Based on these findings, it can be said that this questionnaire is a reliable and valid measure of the QOL for people with a missing tooth.
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Fujio Tsuchida, Toshio Hosoi, Kaoru Kobayashi
1999 Volume 43 Issue 4 Pages
706-710
Published: August 10, 1999
Released on J-STAGE: August 10, 2010
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A rotational panoramic radiography was used for quantitative analysis of mandibular bone resorption, and measurement of mandibular corpus height by new device of the mandibular positioner was made possible. The purpose of this study was to make a comparison between the mandibular corpus height and occlusal rim height.
Twenty edentulous patients whose maxillomandibular relations had been recorded were selected as subjects. Eight metal tubes were vertically placed in the occlusal rim of each subject at the crest of the mandibular corpus, and the occlusal rim height where the metal tubes were located was directly measured by a digital readout caliper.
A rotational panoramic radiograph was taken, the magnification rate of metal tubes was estimated by calculating, and the relationships between mandibular corpus height and occlusal rim height were investigated. The low residual ridge group tended to show high occlusal rim height, whereas the high residual ridge group showed the opposite tendency.
These results suggested that the occlusal rim height was influenced by the mandibular corpus height. The measurement of mandibular corpus height by rotational panoramic radiography might be useful to determine the occlusal plane of an edentulous patient.
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Xiao Rong Wang, Shinsuke Koyanagi, Yutaka Takahashi, Tetsuya Habu
1999 Volume 43 Issue 4 Pages
711-718
Published: August 10, 1999
Released on J-STAGE: August 10, 2010
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The dimensional changes of denture base of mandibular complete dentures following polymerization were measured by using a three-dimensional measurement system. The mandibular complete dentures processed by injection type microwave-cured resin, conventional type microwave-cured resin and heat-cured resin were compared. Within the conditions imposed in the study, the results were as follows:
1. The mandibular complete denture processed by three methods showed minor dimensional changes after deflasking at a distance between alveolar ridge of second molars and incisal alveolar ridge compared with that distance between right and left alveolar ridges of the second molars.
2. The mandibular complete denture processed by three methods showed minor dimensional changes after deflasking at a distance of second molars and second premolars between right and left alveolar ridges compared with that distance between right and left buccal flanges and lingual flanges.
3. The mandibular complete denture processed by heat-cured resin showed minor dimensional changes compared with that processed by injection type microwave-cured resin and conventional type microwave-cured resin after defrasking.
4. The denture processed by injection type microwave-cured resin and conventional type microwavecured resin and heat-cured resin showed a gradual dimensional change.
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Yasuko Takayama, Yoshiyuki Kawai, Norio Takishin, Toshio Hosoi, Yukihi ...
1999 Volume 43 Issue 4 Pages
719-731
Published: August 10, 1999
Released on J-STAGE: August 10, 2010
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The present study was conducted to evaluate discoloration and accretion on the polished surface of dental cast metal in the oral cavity. The metal surface was observed and evaluated using an electron probe X-ray micro analyzer. Prosthetic appliances that have 12 Wt% Au-Ag-Pd alloy were also treated and observed in the same manner.
The results were as follows:
Analysis of the constituent materials of the denture
1. According to gross assessment of discoloration and accretion done on each sample, a wide variance was observed between individual patients.
2. The least surface roughness following polishing was observed in Au-Pt alloy and the largest in titanium prior to treatment. However, the titanium sample showed the least surface roughness after two months of treatment.
3. According to the results of qualitative analysis, elements such as 0, C, P and Ca were detected after two months of treatment.
4. A larger amount of accretion was found on 12 Wt% Au-Ag-Pd alloy than other metal materials.
Analysis of prosthetic appliances
Elements such as C and S were detected on the appliance without discoloration and these elements as well as 0, P and Ca were detected on the discolored appliance.
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Part 2 Colorimetric Study of Low Fusing-porcelain
Yasuhito Takeuchi, Toshiyuki Abe, Takashi Yamauchi, Yutaka Ito
1999 Volume 43 Issue 4 Pages
732-738
Published: August 10, 1999
Released on J-STAGE: November 26, 2010
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The purpose of this study was to investigate the color tone of porcelain and stabilization of porcelain's color by fusing repetition using the restoration system. Three kinds of porcelain for ceramometal restorations, Carrara porcelain of Carrara system, Deguceram gold of the Golden Gate system and Unibond Vintage, were investigated.
A spectrophotometer was used to measure the color tone of the porcelain (Vita shade: A 3) and stabilization of porcelain's color by fusing repetition. The measured color was evaluated in terms of the CIELab system.
The results were as follows:
1. The lightness of Carrara porcelain of Carrara system and Deguceram gold of the Golden Gate system showed a higher value than that of Unibond Vintage repetition.
2. The color tone of Carrara porcelain of Carrara system and Unibond Vintage did not change by fusing.
3. The porcelain's color of Deguceram gold of the Golden Gate system changed at the 5 th fusion.
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The Effect of Abutment Teeth, Surface Roughness and Temporary Cementation Procedures
Satoru Kon
1999 Volume 43 Issue 4 Pages
739-749
Published: August 10, 1999
Released on J-STAGE: August 10, 2010
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Various abutment materials [Dentin, Au alloy (Au), Pd alloy (Pd), Cosmo] were studied to see how their differences in surface roughness (R, F), and conditions of temporary cementation (R-HYB, F-HYB) would affect shades of all ceramic crowns. A 1, A 2 and A 3 shades of IPS Empress
® were selected, the shade changes depending on abutment teeth condition were studied, and the color differences were determined. The conclusions were as follows:
1. In A 1 and A 2 specimens, surface roughness affected the color difference with Au and Pd. In the case of Dentin and Cosmo, temporary cementation affected the color difference. A 3 specimens did not seem to be affected by either factor.
2. As for the color difference from the comparative standard color, just “slight” or “noticeable” differences were observed with Dentin's all specimens and Pd's A 3 specimens. Color difference value in the vicinity of 2.0 was seen in Dentin's all specimens and Pd's A 3 specimens except F-HYB. Metal color specimen except Pd's A 3 specimen R and R-HYB showed “noticeable” evaluation conditions, and F and F-HYB showed “appreciable” evaluation condition.
3. As a result of the analysis with 3-way ANOVA to compare color differences involving various abutment materials, surface roughness and temporary cementation, it was found that highly significant relations were found in abutment materials, significant relations existed in surface roughness, and no relations were observed in temporary cementation.
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Kazuhiko Suzuki, Takayuki Terui, Shigemi Nagai, Tsukasa Shioyama, Kanj ...
1999 Volume 43 Issue 4 Pages
750-754
Published: August 10, 1999
Released on J-STAGE: August 10, 2010
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For the usage of IPS-Empress crowns, a shoulder preparation must be done. This study evaluated the compressive strength of IPS-Empress crown with different shoulder angles. Three types of abutment having 90, 105 and 120 degree shoulder angle were used, and two types of crowns with shapes of flat (Sample F) and tapered (Sample T) occlusal surface were tested. Crowns were fabricated according to the manufacture's instructions and cemented to metal abutment with zinc-phosphate luting cement. Compressive strength was tested using an Auto-Graph DDS-5000 with a constant strain rate of 0.05mm/min. The mean compressive strength for sample F was 165.1±11.9 kgf for shoulder angle 90 degrees, 166.8±9.9 kgf for 105 degrees and 173.0±4.3kgf for 120 degrees. Statistical analysis (ANOVA and Newman-Keuls test) revealed that there is no differentiation among the compressive strength of three types of shoulder angle in sample F. On the other hand, the strength was 125.6±16.0kgf for shoulder angle 90 degrees, 134.5±5.7kgf for 105 degrees and 158.3±12.2kgf for 120 degrees for sample T, and the crowns with 120-degree shoulder angle showed a significantly higher strength than the other angles. It was concluded that, in crowns with tapered occlusal surface simulating a more clinical occlusal stress, 120-degree shoulder angle has the advantage of prevention of compressive stress.
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Kazumasa Kato
1999 Volume 43 Issue 4 Pages
755-756
Published: August 10, 1999
Released on J-STAGE: August 10, 2010
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Akiko Nomura
1999 Volume 43 Issue 4 Pages
757-758
Published: August 10, 1999
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Masumi Sasaki
1999 Volume 43 Issue 4 Pages
759-760
Published: August 10, 1999
Released on J-STAGE: August 10, 2010
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Kazuhiro Kobayashi
1999 Volume 43 Issue 4 Pages
761-762
Published: August 10, 1999
Released on J-STAGE: August 10, 2010
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Kan Nagao
1999 Volume 43 Issue 4 Pages
763-764
Published: August 10, 1999
Released on J-STAGE: August 10, 2010
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