Distraction osteogenesis is widely used for the treatment of craniofacial deformities. In patients with cleft lip and palate, distraction osteogenesis can be employed to repair the alveolar cleft. In this report, we describe the management of three cases of unilateral cleft lip and palate by interdental distraction osteogenesis. Interdental distraction osteogenesis of the maxillary bone was performed to reduce the width of the alveolar cleft in these patients in conjunction with orthodontic treatment. Tooth-tooth type distraction devices were fabricated and delivered at the same time as osteotomy. Distraction was continued until the midline of the dentition coincided with the facial midline, and until the width of the alveolar cleft was reduced to the width of lateral incisor or had closed. One month after distraction was complete, orthodontic treatment with an edgewise appliance was initiated, and neighboring teeth were moved into the newly created bone. A favorable treatment outcome was achieved in all three cases.

View full abstract

Clinically, the incidence of postoperative nausea and vomiting (PONV) may be higher in mentally challenged patients than in normal healthy patients. The aim of this study was to investigate the risk factors for PONV after day care general anesthesia in mentally challenged patients undergoing dental treatment. We analyzed data on 231 day care general anesthesia cases involving mentally challenged patients undergoing dental treatment. Anesthetic records for the past 5 years were investigated retrospectively. Ten items (age, body weight, sex, duration of general anesthesia, use of propofol, use of sevoflurane, use of nitrous oxide, use of neostigmine, treatment accompanied with bleeding, and transfusion volume) were selected as risk factors for PONV. Postoperative nausea and vomiting was evaluated using the postoperative check sheet and linear discriminant analysis was performed to distinguish PONV incidence using the 10 items as independent variables. The reliability of the linear discriminant function was evaluated using a misjudgment rate and information criteria (AIC). Postoperative nausea and vomiting was observed in 13 cases out of 231 cases. The discriminant function with the smallest AIC (-25.0718) consisted of two independent variables: y=-0.077x₁-0.001x₂+0.0716(x₁=use of propofol, x₂=age). The misjudgment rate was 31.6%. This result suggests that PONV decreases when propofol is used and that the incidence of PONV decreases with age. To investigate other risk factors, an additional analysis was performed using 83 out of the 231 cases in which sevoflurane was used as an anesthetic agent. The results of the subgroup analysis suggest that the incidence of PONV decreases in male patients and higher weight patients, although the patient's body weight may be related to age, as the study cohort included many children. It is suggested that the major risks for PONV in mentally challenged patients after day care general anesthesia are no use of propofol, lower age, female sex and lower weight.

View full abstract

The purpose of the present study was to determine the relationship between cross-sectional design and fracture load using a static load bearing test in yttria-stabilized tetragonal zirconia polycrystal ceramic frameworks on a molar fixed partial denture. The test framework was designed as a 3-unit bridge with two abutment teeth at the second premolar and second molar of the mandible. The cross-sectional area of the connector was 9.0, 7.0, or 5.0mm². In terms of shape, the cross-section was either circular or oval, with a height/width ratio of 1:1, 3:4, or 2:3. For each of the 9 combinations of cross-sectional area and shape, 5 frameworks were prepared (45 in total). Frameworks were cemented to a metallic test model with adhesive resin cement. After fracture load was measured, the percentage of fracture sites was determined and the fracture surfaces observed. In terms of cross-sectional area, there was a statistically significant difference in fracture load between 9.0, 7.0, and 5.0mm². No significant difference in fracture load was observed between any two shapes of connector (p>0.05). The fracture load of all frameworks with a cross-sectional area of 9.0 or 7.0mm² was over 880 N, which was recognized as parafunctional occlusal force. Fracture occurred at the distal connector in 82.2% of all frameworks on average. Fracture load decreased as cross-sectional area of the connector became smaller. The cross-sectional shape used in the present study was less influential on fracture load. It appears to be clinical possible to apply a connector with a cross-sectional area of 7.0mm². Fracture often occurred at the distal connector between the pontic and the abutment, corresponding to the second molar.

View full abstract

The aim of the present study was to determine the reason isolated single Merkel cells do not respond to mechanical stimulation by fluorescent or histological techniques. Cells identified as Merkel cells by quinacrine fluorescence and measurement of intracellular calcium concentration were observed by transmission electron and scanning electron microscopy. Observations elucidated that the cylindrical cytoplasmic processes of single Merkel cells disappeared with time shortly after isolation. Transmission electron microscopy revealed the presence of numerous dense-cored granules, which may function as sensory receptors in the cytoplasm of the isolated single Merkel cell. Disappearance of the cylindrical cytoplasmic processes impeded reception of mechanical stimulation. The results suggest that an isolated single Merkel cell continues to function as a sensory receptor cell due to the presence of numerous dense-cored granules. Furthermore, the results show that an isolated single Merkel cell is not an appropriate specimen for investigation of mechanically-gated channels.

View full abstract

The objective of this study was to three-dimensionally observe the morphological characteristics of mesiobuccal root canals of Japanese maxillary first molars using microcomputed tomography (Micro-CT) and classify root canal variations. This study used 90 maxillary first molars. Three-dimensional reconstruction was performed using data obtained by Micro-CT, and cross-sections of the root canals were observed. Moreover, the root canal morphology was classified by the configuration and root canal diameter, and was evaluated for occurrence using the classification by Weine et al. (1969) as a reference. Overall, single root canals were observed in 44.4%, incomplete separation root canals in 22.3%, and completely separate root canals (upper and lower separation root canals) in 33.3%. Mesiobuccal root canals often had intricate configurations, and accessory root canals (lateral canals and apical ramifications) were observed in most of the mesiobuccal root canals (76.7%), irrespective of whether there were ramifications of the main root canals. While there were no marked differences in the incidence of root canal ramifications between this study and earlier reports, the incidence of accessory root canals was higher in this study. This result may be explained by the far more superior visualization ability of Micro-CT than conventional methods, which allowed the detection of microscopic apical ramifications previously difficult to observe.

View full abstract

Metals used in the oral cavity have been reported to cause various allergic diseases of the skin and mucosa. Skin manifestations due to dental restorations appear not only in the oral cavity, but also on the hands, feet or the whole body, as in the cases of pustulosis palmoplantaris and lichen planus. These phenomena implicate different pathogeneses from that of conventional skin sensitization and tolerance. Therefore, we compared skin and oral mucosa sensitization with nickel and oral tolerance for nickel in a mouse model. Female C57BL/6J mice were sensitized by injection of NiSO₄ into the skin or oral mucosa. Allergic reactions were evaluated by the mouse ear swelling test and splenocyte proliferation and cytokine profiles. Skin and oral mucosa sensitization succeeded in all mice. Ear swelling was significantly greater in the skin- than in the oral mucosa-sensitized mice at 48 hr after challenge. Ear swelling was also suppressed by single oral administration of NiSO₄ in both the skin- and oral mucosa-sensitized mice to the level of that in nonsensitized mice. Splenocytes from skin-sensitized mice proliferated similarly to those from oral mucosa-sensitized mice. Splenocytes from orally-tolerized mice also showed similar proliferation activity to those from skin and oral mucosa-sensitized mice. In the challenge phase, IL-2, IFN-γ, and IL-10 production was induced in splenocytes from both skin- and oral mucosa-sensitized mice. However, IL-4 was induced only in those from skin-sensitized mice. In addition, IL-4 in splenocytes from oral mucosa-sensitized mice was up-regulated to the level in those from skin-sensitized mice by oral tolerance. These results suggest that sensitization sites in mice influence not only the degree of excitation, but also Th-1 and Th-2 balance in the challenge phase and oral tolerance.

View full abstract

This study investigated the effects of diode (GaAlAs) laser irradiation at an effective energy density of 5 or 20 J/cm² on cell growth factor-induced differentiation and proliferation in pheochromocytoma cells (PC12 cells), and whether those effects were related to activation of the p38 pathway. Laser irradiation at 20 J/cm² significantly decreased the number of PC12 cells, while no difference was seen between the 5 J/cm² group and the control group (p<0.05). Western blotting revealed marked expression of neurofilament and β-tubulin, indicating greater neurite differentiation in the irradiation groups than in the control group at 48 hr. Irradiation also enhanced expression of phospho-p38. The decrease in number of cells after laser irradiation was accelerated by p38 inhibitor, while neurite differentiation was up-regulated by laser irradiation, even when the p38 pathway was blocked. This suggests that laser irradiation up-regulated neurite differentiation in PC12 cells involving p38 and another pathway.

View full abstract