Dynamic palatography was used to identify contact patterns of tongue-to-palate and tongue-to-teeth movements in a complete denture wearer during production of the following sentence : [sakura-no-hana-ga-sakima∫ita].
The palatography sensor was of the thin-film type with 96-electrode arrays and covered the subject's existing maxillary complete denture. Real-time recordings of the speech sound wave and the tongue-to-sensor touch signals were obtained simultaneously. The speech sound wave, spectrum, and palatogram were then simultaneously displayed on a Computerized Speech Lab (Kay, model 4300 B).
Comparison of the contact patterns of the subject with the standardized patterns from 18 dentulous adults revealed that the patterns for [s], [∫], and [t] sounds were similar, whereas pattern for [k], as produced in [ki] of the test sentence, differed markedly.

View full abstract

Nine commercial composites were evaluated for filler content, filler morphology, fracture toughness test, and bending test to understand the relation between the filler type and mechanical properties. Filler content differs in the products with the range of 53-86 wt%. According to the morphology of filler observed by backscattered electron images and filler content, composites tested were divided into 3 categories such as high, medium, and low loaded type. Fracture toughness of high, medium, and low loaded type was 1.8-2.0 MPa·m^1/2, 1.2-1.4 MPa·m^1/2, and 0.9-1.1 MPa·m^1/2 in order. Bending strength of high, medium, and low loaded type was 150-180 MPa, 130-140 MPa and 80-90 MPa in order. Young's modulus of high, medium, and low loaded type was 15-18 GPa, 9-12 GPa, and4. 5-5.5 GPa in order. These results indicated mechanical properties of composites differed in filler categories. Mechanical properties of composites were influenced by the filler content, which was depended on the filler type categorized. There was high correlation between the filler content and mechanical properties of composites. Therefore, classification of composite by filler type proposed in this study was available for estimating mechanical properties of composites.

View full abstract

5-HT (0.01-10μM) contracted isolated hilar bronchus from guinea pig treated with tetrodotoxin in a concentration-dependent manner. 5-HT ₂-agonists, such as 5-methoxytryptamine (5-MeOT) and α-methyl-5-HT (α-Me-5-HT), also caused a similar contraction to 5-HT. Other types of 5-HT agonists, such as 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT, 5-HT₁ agonist) of 2-methyl-5-HT (2-Me-5-HT, 5-HT₃ agonist) cause no obvious contraction in the preparation. The concentration-response curve of 5-HT was inhibited by the 5-HT₂ antagonists, ketanserin, ritanserin, LY53857 and 1-(3-chlorophenyl) piperazine (mCPP) in a concentration-dependent manner, while the maximum response of 5-HT was reduced by them. These results suggest that 5-HT-induced contraction may be mediated through an action on 5-HT₂-like receptors, and that the receptors mediating the responses of 5-HT in hilar bronchus are different from those in other tissues in their pharmacological profile.

View full abstract

This study was carried out to determine statistical information concerning the crowns and the fixed partial dentures (total number, type and rate of crowns, number of vital or non-vital abutment teeth, etc.) which were placed in the outpatients in the Department of Fixed Prosthodontics at Showa University Dental Hospital from April 1996 to March 1997.
The following results were obtained :
(1) The total number of crowns and fixed partial dentures produced were 1,072; among them, crowns totaled 889 (82.9%) and the fixed partial dentures, 183 (17.1%).
(2) Most of the crowns were full cast crowns (495, 55.7%); the second most commonly produced was resin faced cast crowns (185, 20.8%), the third was porcelain fused to metal crowns (145, 16.3%). For the first time in the statistics of fixed prosthetic restorations, the number of resin faced cast crowns was more than the porcelain fused to metal crowns.
(3) Resin faced cast crowns and porcelain fused to metal crowns were most commonly used for the anterior teeth; full cast crowns and porcelain fused to metal crowns, for the premolar teeth; full cast crowns, for the molar teeth.
(4) Fixed partial dentures located in the posterior region were about 60%; those in the anterior and the antero-posterior regions were about 20% each.
(5) With regard to the relationship between the missing teeth and the abutment teeth of the fixed partial denture, three-unit fixed partial dentures (one missing tooth with two abutment teeth) were most frequently treated in all regions.
(6) The crowns covered by the insurance dental service were 77.5%; the fixed partial dentures were 69.9%.
(7) Concerning the abutment teeth of the crowns, non-vital teeth were 87.3%, implant abutments were 3.0%; non-vital teeth of the fixed partial dentures were 72.0%; although implant abutments were used last year for the first time to make fixed partial dentures, this year they were not used.

View full abstract

Recently, Er:YAG laser has been used in dental clinic to ablate dental hard tissues in anticipation of replacing the high speed dental drill. This study was designed to investigate the microstructural changes of dental hard tissues and pulpal response with Er:YAG laser irradiation delivered via the oxide-germanium fiber.
To investigate microstructural changes, Er:YAG laser irradiation was performed at the distance of 1 mm to human enamel and dentin with or without water irrigation at 200 mJ/pulse, 20 pps, 3 W for 10 s. The microstructural changes of the areas ablated by the laser were investigated by stereomicroscopy, SEM, SEM-EDX, and scanning laser microscopy. To investigate pulpal reaction, Er:YAG laser irradiation was performed with water irrigation to anterior and premolar teeth of a monkey at the same condition. Specimens were evaluated by light microscopy in the sections stained with hematoxylin-eosin.
In stereomicroscopic and SEM observation, no carbonization, melted surface, crack, or smear layer was observed when irradiated with water irrigation, but in the specimens irradiated without water irrigation, there were thermal morphological changes. In SEM-EDX analysis, weight percentages of Ca or P at the irradiated areas were increased remarkably, but Ca/P mol ratio was not changed. In the scanning laser microscopic observation, the deep ablation with both the clear bounds and smooth dentin or enamel surface was formed by Er:YAG laser irradiation with water irrigation. Regarding pulpal reaction, there was no clear difference between the ablation by Er:YAG laser irradiation with water irrigation and the cavity preparation by high speed air turbine with water.
These results suggest that Er:YAG laser irradiation with water irrigation can remove dental hard tissues with similar damage to that by high speed air turbine.

View full abstract

Bonding of the impression material and abutment tray is important to carry out the acrylic resin abutment tray impression technique more accurately using silicone rubber impression materials. Conventionally, there are adhesive problems for addition-type silicone rubber impression materials : bond strength, film thickness and difficulty of drying. In this study, ten different addition-type silicone rubber impression materials (four hydrophobic and six hydrophilic types) were used. The adhesives of the impression materials were evaluated to determine their tensile bond strengths with the self-curing resins (materials of the abutment tray). In addition, the bonding primer for silicone denture relining materials that have been developed recently was examined for the possibility of the application to the adhesives for the acrylic resin abutment tray impression technique using addition-type silicone rubber impression materials.
The results were as follows :
1) Some manufacturers recommended adhesives that did not have sufficient bond strength clinically.
2) This primer was thin, fast drying and easy to use.
3) This primer showed greater bond strength in comparison with the manufacturer's recommended adhesives except for EXAFINE and EXAFLEX and had sufficient bond strength clinically.
Therefore, it was suggested that this excellent operational primer is effective as an adhesive for the acrylic resin abutment tray impression technique using addition-type silicone rubber impression materials, although this material requires attention to the affinity with impression materials.

View full abstract

The purpose of this study was to investigate the relationship between treatment results and evaluation and influencing the attainment of individual normal occlusion.
This time, we report the factors related to the results of skeletal class 2 after extraction or non-extraction treatment, which were excellent or poor.
The subjects were 120 patients with upper protrusion visiting Showa University Dental Hospital, Department of Orthodontics. We measured the initial and finishing stages by lateral cephalometric points.
The results were as follows :
1. The factors considered for results in extraction cases were growth direction of the mandible (gonial angle), improvement of ANB, changing pattern for setting overjet and overbite, occlusal plane angle and palatal plane angle.
2. The factors considered for results in extraction cases were growth direction of the mandible (gonial angle, mandibular plane angle), improvement of ANB, changing pattern for setting overjet and overbite and occlusal plane angle

View full abstract

For the purpose to study the relationship between the stress to the bone and the arrangement of the bone lamellae and matrix fibers of the compact bone, we examined the arrangement of matrix fibers of tibiae dissected from male cadavers for anatomy with a high-resolution scanning electron microscope.
On the medial and lateral surface of Corpus tibiae, matrix fiber bundles of collagen fibrils ran in parallel along the axis of the bone. The interosseus membrane entered into the matrix fiber bundles about 500 μm in width at the lateral border of Corpus tibiae. On the lateral and medial surface of the proximal end of Corpus tibiae, matrix fiber bundles mingled each other, and the tendons of M. tibialis anterior and M. sartorius entered into bone matrix. On the posterior surface of the proximal end of Corpus tibiae, matrix fiber bundles mingled. On the posterior surface of the central and lower part, matrix fiber bundles ran in parallel along the long axis of the bone. The matrix fiber bundles of the internal surface of Corpus tibia ran along the long axis of the bone.
At the external basic lamellae, the lamellae about 5 μm and 3 μm in thickness arranged alternately. At the Haversian lamellae, the lamellae about 4 μm and 2 μm in thickness arranged alternately. The former lamellae were composed of fiber bundles running along the long axis of the bone, and the latter lamellae were composed of fiber bundles running concentrically.

View full abstract

We have focused on the order of eruption of permanent dentition in children with cleft lip and/or palate (cleft children). The eruption order of the permanent teeth is said to have recently changed from the first molar to the central incisor. Does this phenomena tend to apply to cleft children as well? We tried to examine the order and timing of the eruption of the permanent teeth, in terms with the type of cleft and the craniofacial morphology obtained by cephalometric analysis of 220 cleft children (105 male and 115 female) at the age of six. The cephalograms from 290 non-cleft children (143 male and 147 female) were used as the control. The subjects were further divided into I-type (the incisor erupted first) and M-type (the first molar erupted first) according to the type of cleft (UCLP, BCLP, ICP, UCLA, CL).
The results were as follows. Percentages of I-type children among the four groups were all over 50% and ranked in the order of cleft male > non-cleft male≅cleft female > non-cleft female. Percentages of I-type children with UCLP and BCLP were far over 70% for all types of cleft children. Linear measurements indicated that the length of anterior cranial base, anterior facial height and mandibular overall length of the M-type cleft male tended to be longer than those of the I-type cleft male. On the other hand, no definite difference in size was found between the two types of cleft female.
With these results, it might be concluded that the percentage of I-type in males exceeds that in females, and furthermore, the frequency of I-type with cleft children is dominant over that with non-cleft children.
The cephalometric findings also suggested that the morphology of maxillo-facial complex and mandible with I-type cleft male might be different from those with M-type cleft male.

View full abstract

The eruption order of permanent teeth has recently changed from the first molar to the central incisor in children with cleft lip and/or palate. Part 1 of the present study suggested that these changes might be associated with morphologic changes of maxillo-facial complex, especially for male children at the age of 6 years. The cleft lip and/orpalate children were divided into I-type (the incisor erupted first) and M-type (the first molar erupted first) groups. The percentages of various types of cleft lip and/or palate (UCLP, BCLP, ICP, UCLA, CL) among I-type male, M-type male, I-type female and M-type female were examined. In addition, morphological comparisons of maxillo-facial complex between I-type and M-type were evaluated by the use of lateral cephalograms which had been taken of the same children at the age of 6, 8 and 10 years, respectively. The following results were obtained.
1. The percentages of various types of cleft lip and/or palate for I-type male/female ranked in the order of UCLP>ICP>BCLP>UCLA>CL. On the other hand, the percentages for M-type male/female were ranked ICP>UCLP>UCLA>BCLP>CL.
2. The longitudinal male cephalometric comparison between I-type and M-type indicated that total facial height (N-Me) and mandibular length (Gn-Cd) obtained from M-type children were greater than those from I-type children, and the angular measurements of ANB and IMPA obtained from I-type children were greater than those from M-type children. These findings suggested that the cephalograms of M-type male had skeletal class III tendency. On the other hand, the longitudinal female cephalometric comparison between I-type and M-type children did not show any significant difference.
These results suggested that the cephalometric differences between M-type and I-type cleft male patients at the age of six were obvious, and similarly, those between M-type and I-type cleft male patients at the age of eight and ten became even more clear.

View full abstract

The Ultrastructural organization of elastic fibers in the human adult temporomandibular joint disk was studied by light and electron microscopies. The disks were selected from human adult cadavers ranging in age from 56 to 68 years. The elastic fibers of the disk having a diameter of about 1μm were found to consist of two different components by scanning electron microscopy of KOH-collagenase treated specimens and transmission electron microscopy of tannic acid-stained ultrathin sections : the components were a central, somewhat amorphous material composed of densely stained microgranular structures and microfibrils arranged parallel to the fiber long axis. The microfibrils frequently decreased and lacked. The elastic fibers arranged almost parallel to collagen fibril bundles and run anteroposteriorly and mediolaterally in the anterior band of the disk. The fiber arrangement was in an almost anteroposterior direction in the intermediate zone and irregularly interlaced in the central area of the posterior band. The elastic fibers demonstrating a linear, wavy or branching appearance were seen at the rear area of the posterior band, which consists of the fibril bundles directed toward the bilaminar zone. The organization of the elastic fibers in the disk may result in assistance of the fibril bundles resistant to tension, permission of a faint elongation in the anteroposterior sliding of the disk, and stress relaxation in functional pressure. Oxytalan fibers categorized with elaunin and elastic fibers in the elastic system fibers were found not to distribute noticeably in the disk area of the present study by light microscopy of preoxidized specimens and transmission electron microscopy.

View full abstract