Morphological studies of the submandibular glands in the spontaneous type 2 diabetes mellitus (DM) model rats (Goto-Kakizaki: GK) are currently lacking. We investigated the morphological differences in the submandibular gland of two kinds of rats : spontaneous type 2 DM male rats and normal Wistar male rats (control). A total of 18 rats were used in the study : 9 GK rats in the DM group (fasting blood glucose level, 240.9 ± 58.0 mg/dL ; HbA1c level, 5.8 ± 0.3%) and 9 Wistar rats in the control group (fasting blood glucose level, 108.4 ± 39.7 mg/dL ; HbA1c level, 5.1 ± 0.3%). We investigated the cross-sectional area of the serous cells (n = 3, light microscopic specimens), the acinus diameter (n = 3, surface morphology specimens), and the diameter of the capillaries around the acinus (n = 3, microvasucular corrosion cast specimens). The surface morphology and microvasucular corrosion cast specimens were investigated using a scanning electron microscope. Image and statistical analysis revealed that the cross-sectional area of the serous cell, the acinus diameter, and the capillary diameter around the acinus were significantly smaller in DM rats than in normal rats. We think that hyperglycemia caused these observed atrophic changes in the serous cells, the acinus, and the diabetic microangiopathy of capillaries around the acinus in the GK rats.
This study was performed to clarify the effect on retentive force of negative pressure generated between the improved inner zirconia crown and outer electroformed crown during vertical dislodgement. Inner crowns with 2° taper and a combination taper (0° taper for the cervical 1.5 mm and 2° taper above that) were made of zirconia, and five outer crowns were made by electroforming on the inner crowns. We measured the retentive force and the negative pressure generated between the inner and outer crowns with 20%, 40% and 60% glycerin solution substituted for saliva. There was no difference in peak retentive force between the 2° taper crowns and the combination taper crowns. The retentive force generating distance with the combination taper was significantly greater than with the 2° taper, and increased with the glycerin concentration of the solution in the combination taper type. The negative pressure generated between the double crowns using a zirconia inner crown with a combination taper increased with the glycerin concentration of the solution. The above findings suggest that the negative pressure generated between zirconia inner crowns and electroformed outer crowns increases the retentive force generating distance as the saliva viscosity increases.
The bite impression technique has been developed and applied in the fabrication of crowns. However, few reports have demonstrated its accuracy in reproducing the occlusal contacts of implant superstructures. We investigated the bite impression technique for its reproducibility of occlusal contacts on working casts for implants. Eight patients were selected who each had a single-tooth implant to replace a missing posterior tooth. A custom device was created to measure occlusal contacts and their relationship with the opposing teeth and the implant body. Image analysis was used to compare intraoral measurements from working casts made from a bite impression with those from the open tray impression technique. Good reliability was determined for the measuring device and measurements in this study. We found that the occlusal contact points and areas on the custom measuring device were significantly better for the working casts made from bite impressions than for those from open tray impressions (p<0.001). Furthermore, significant differences were observed in the occlusal contact areas and contact points on both teeth adjacent to the implant (p≦0.001), with the bite impression working casts significantly more reproducible than the open tray impression casts. Our data suggest that the bite impression technique accurately reproduces occlusal contacts for implants.
We evaluated new bone formation on the nano-modified surfaces of titanium plates implanted in the rat femur by comparing the ratio of bone-to-implant contact (%BIC). To create the nanostructure, titanium discs were incubated in a 10 M NaOH solution at 30℃ for 24 h, and then washed and dried. Plates of titanium with nanostructures (the experimental group) and unprocessed titanium 1 mm thick and 4 mm in diameter (control group) were implanted into the femurs of the rats. After 14, 21 and 28 weeks, the %BIC for the control and experimental groups was 0.2% and 3.6% at 2 weeks, 18.2% and 24.7% at 3 weeks, 37.5% and 53.0% at 4 weeks respectively. These data suggest that modifying the nanostructure of the titanium surface, which is one of the main materials used in implants, allows induction of bone formation.
Oral cancer treatment may have significant adverse effects on the patient's activities of daily living (ADL) and quality of life (QOL). In recent years attention has been focused on the use of food for chemoprevention. (-)-Epigallocatechin-3-gallate (EGCG), which accounts for about half of green tea catechins, is not only a strong antioxidant, but has also been reported to possess anti-tumor and carcinogenesis-inhibiting actions. As the oral mucosa comes into direct contact with green tea, its carcinogenesis-inhibiting action may be effective against oral cancer. We investigated the carcinogenesis-inhibiting activity of EGCG in the carcinogenic process in rats with tongue cancer induced by 4-nitroquinoline 1-oxide (4NQO). Sprague-Dawley (SD) rats were given water containing either a 50-ppm aqueous solution of 4NQO to induce tongue cancer or the 4NQ0 solution together with a 500-ppm aqueous solution of EGCG. A control group was given only distilled water. Macroscopic observations and histopathologic comparisons were made of the back of the tongue at 8, 12, 16, 20 and 24 weeks after the start of administration. The association between activated nuclear factor κB (NF-κB) p65 and IκB kinase α (IKKα) expression and tumor growth in the carcinogenic process was investigated by immunohistochemical staining and immunoblotting. The administration of EGCG not only significantly suppressed the occurrence of epithelial dysplasia and squamous cell carcinoma in rats with 4NQO-induced tongue cancer, but also inhibited the expression of activated (NF-κB) p65 and IKKα (p<0.05). It also decreased the proportion of Ki-67-positive cells, and inhibited cell proliferative activity (p<0.05). Western blotting was performed for these proteins, and the same results were also obtained for their expression via immunostaining. These results suggest that the carcinogenesis-inhibiting action of EGCG is probably due to the inhibition of activated NF-κB p65, and that long-term administration of EGCG may decrease IKKα expression, increasing its activity in suppressing the promotion of carcinogenesis and suppressing multi-step carcinogenesis.
Although numerous studies using surface electromyography (EMG) have been conducted, few have examined the relationship between respiratory state and respiratory muscle activity. The location of the respiratory muscles deep in the neck makes their EMG signal-to-noise ratio poor and quantitative measurement difficult. To resolve this problem, we monitored an accessory inspiratory muscle in the neck with the Bagnoli-2 EMG system that effectively eliminates noise. From the data obtained we analyzed the relationship between respiratory state and inspiratory muscle activity by focusing on spike count per minute. Participants were four men and one woman, none of whom had impaired respiratory function. We recorded EMG data for 1 min using four electrodes placed on the sternocleidomastoid muscle. Measurements were made for the following sequence of respiratory states : (1) rest, (2) deep breathing, (3) tachypnea, and (4) rest again. For each respiratory state, we computed the spike count per minute by adding the spike counts obtained in 0.1s increments. EMG of the activity most frequently observed in a preliminary experiment during maximum voluntary contraction (MVC) was observed and normalized according to the maximum value observed in tachypnea. For analysis, we compared the normalized values of the examined respiratory states. Relative to 100% for tachypnea, the average MVC ratio was 48.9 ± 9.98% for rest, 66.7 ± 12.9% for deep breathing, and 61.5 ± 18.1% for rest again. In all participants, the MVC ratio for tachypnea was significantly different from the MVC ratios for the other respiratory states. No significant differences in MVC ratio were found between rest, deep breathing, and rest again. By determining the spike count per minute, we quantitatively evaluated the relationship between respiratory state and inspiratory muscle activity. This method enabled us to compare the MVC ratios for rest, deep breathing, tachypnea, and rest again uncompromised by noise, and the results showed an activity pattern suggesting that the sternocleidomastoid muscle is an inspiratory muscle.
Cyclic mechanical load is thought to play a major role in temporomandibular disorder (TMD). We developed the cyclic loading bioreactor, in which matrix metalloproteases (MMPs) and a disintegrin, and metalloproteinase with thrombospondin motifs (ADAMTSs) are induced by mechanical stimulation to three-dimensional (3D) cultured tissue. The purpose of this study was to examine the effects of NSAIDs on the gene expressions of ADAMTSs, MMPs, and the protein expression of PGE2. Human synovial cells were seeded onto a collagen scaffold to construct 3D cultured tissue. Celecoxib or indomethacin were added to the culture media before cyclic compressive load. Cyclic compression was then applied to 3D tissues. After 6 hours, the media were assayed for PGE2 by HTRF®. The mRNA expression of the 3D tissue was quantitatively determined by real time RT-PCR. We found that mechanical stress to the human synovial cells in 3D culture induced PGE2 production and up-regulated ADAMTS-4 and MMP-1, -3 gene expression. Celecoxib and indomethacin suppressed PGE2. Celecoxib down-regulated mechanically induced ADAMTS-4 gene expression at a lower concentration than indomethacin. These results indicate that celecoxib and indomethacin may have an inhibitory effect on cartilage destruction caused by mechanical stimulus. In addition, celecoxib may contribute to inhibition of cartilage destruction at a lower concentration than indomethacin.
Although synovial chondromatosis (SC) usually affects larger joints such as the knee, elbow, wrist and hip, it rarely occurs in the temporomandibular joint (TMJ). This paper summarizes our cases involving diagnosis and treatment of SC affecting the TMJ. We retrospectively reviewed the clinical data of cases of SC affecting the TMJ in our hospital from 1999 to 2013. Five males and 10 females were included in this group with an average age of 53 years. The duration of symptoms was from 2 weeks to 84 months. The right side was affected in 9 cases and the left in 5, and only one case was bilateral. All of the patients noted TMJ pain and 13 noted joint noise on the affected side. The range of maximum mouth opening was from 28 to 45 mm. Previous treatments included drug therapy (5 cases) and occlusal splint treatment for TMJ disorder (5 cases). Bone changes were noted on the articular surface in 8 cases by conventional radiography (CR) and in 10 cases by computed tomography (CT). Loose bodies were observed in 7 cases by CR and in 10 by CT. Loose bodies were observed with magnetic resonance imaging (MRI) in all cases, and characteristic dumbbell-shaped or small ring-like signals were seen in T2-weighted images. Among the 12 surgically treated subjects, open surgery through a pre-auricular approach was performed in 11 cases, 8 of which were done with arthroscopic assistance. The open surgery consisted of removal of loose bodies and partial synovectomy of the affected areas, both were done in 5 cases, while only the former was done in 7 cases. The final histopathological diagnoses were 9 cases of SC and 2 of synovial osteochondromatosis. The postoperative follow-up varied from 5 to 164 months. Although residual loose bodies in the joint space were found in 3 cases, there was no dysfunction of the TMJ and there were no signs of growth of the loose bodies.
We attempted to clarify the role of the temporomandibular joint (TMJ) sensory receptors on jaw movement. Eight young healthy volunteers participated in this study. All volunteers had a full complement of teeth, optimal occlusion and an absence of any symptoms of TMJ or masticatory muscle dysfunction. Functional jaw movements were monitored before and after saline was injected into the right superior temporomandibular joint cavity. On a different day, functional jaw movements were monitored before and after 2% lidocaine was injected into the right superior temporomandibular joint cavity for sensory deprivation. Recordings of jaw movement were made by monitoring movements of the lower incisors using a model K7 Mandibular Kinesiograph (MKG ; Myotronics Research, Seattle, WA, USA) during unilateral gum-chewing. Following anesthsia to the TMJ on one side, the jaw movements of the chewing path had a more variable pattern in the frontal plane, and the cycle time of each stroke after anesthsia was longer than normal. These findings suggest that sensory receptors in the TMJ contribute to functional jaw movements.
We investigated the possibility of using commercial detector tubes to perform simple environmental measurements. Hydrogen sulfide, hydrogen fluoride, ethylene oxide, isopropyl alcohol, xylene, toluene and formaldehyde detector tubes were used to measure two concentrations each of nitrous oxide (33% and 100%), sevoflurane (50 ppm and 5%), and isoflurane (50 ppm and 5%) inhalation anesthetics. The anesthetics were diluted with air in a fluorine-coated Tedlar bag until the target concentration was attained, and then measured using each detector tube with an electric pump. Sevoflurane and isoflurane at concentrations of 10, 20, 30 and 40 ppm were also subsequently prepared and measured. The formaldehyde detector tube changed color with both low and high concentrations of sevoflurane and isoflurane. However, the entire tube changed color even with the low concentrations, making it impossible to confirm the concentration. Therefore, the formaldehyde detector tube was subsequently used to measure sevoflurane and isoflurane at concentrations of 10, 20, 30 and 40 ppm. Readings for anesthetic concentrations of approximately 1 : 100 were displayed ; however, only approximate values could be obtained due to the indistinct border between the colored and non-colored sections.
The resonance frequency analyzers OsstellTM Mentor (OSM) and Osstell ISQ (OSI) were developed to evaluate the intraosseous stability of implants. We investigated the reliability of implant stability quotient (ISQ) values calculated from these devices. We then examined the effect of dental implant size on differences in ISQ values using the OSI. The results showed that OSM and OSI produced highly reliable ISQ values. In the maxilla, the major axis of the implant had a greater effect on ISQ values than did the diameter. On the other hand, in the mandible, the diameter had a greater effect. The implant size and the implantation site are both important when evaluating ISQ values.