An anonymous questionnaire-based survey was used to determine the current state of and issues involved in undergraduate education in oral implantology at Tokyo Dental College. The participants comprised 139 students who had received lectures on and practical training in oral implantology in 2013. The results indicate that the overall level of student comprehension was high for both lectures and practical training content; the level of difficulty was appropriate for practical training, but the amount of practice time given requires reconsideration. Over 80% of the students gave positive responses in their overall evaluation of lectures and practical training, and the number of students who had an interest in oral implantology after finishing the course and who wanted to be involved in oral implantology as dentists increased. These results indicate that this undergraduate education program is effective in improving understanding of oral implantology. Improvement is required, however, in lecture methodology and practical training content. It is also suggested that the curriculum should be evaluated by students regularly and that the courses be subject to updating as required.
The goal of this study was to compare the apical cleaning capabilities of single files from 3 different rotary systems in the presence or absence of prior cervical preparation based on a histological analysis. A total of 84 human single-rooted mandibular permanent incisors were divided into 6 groups (14 canals each). Cleaning and shaping was performed under the following protocols: Group I, F2 ProTaper at working length; Group II, SX ProTaper and F2 ProTaper; Group III, size 25, .06 taper Mtwo at working length; Group IV, SX ProTaper and size 25, .06 taper Mtwo; Group V, size 25, .06 taper BR3 BioRace at working length; and Group VI, SX ProTaper and size 25, .06 taper BR3 BioRace. After cleaning and shaping, the root canals were evaluated by histological analysis. The percentage of remaining debris was evaluated using a cross-hatched grid superimposed over each image. Data were assessed using the Shapiro-Wilk and ANOVA tests. Statistically significant differences were observed between groups (p =0.0001) with respect to amount of remaining debris; use of SX in conjunction with F2 ProTaper yielded a significantly lower mean percentage of debris. It was concluded that cleaning ability improves when root canal preparation with F2 ProTaper is complemented by prior cervical enlargement.
Streptococcus mutans grows with starch-derived maltose in the presence of saliva. Maltose transported into the cells is mediated by the MalQ protein (4-alpha-glucanotransferase) to produce glucose and maltooligosaccharides. Glucose can be phosphorylated to glucose 6-phosphate, which can enter the glycolysis pathway. The MalQ enzyme is essential in the catabolism of maltose when it is the sole carbon source, suggesting the presence of a downstream glucokinase of the MalQ enzyme reaction. However, a glucokinase gene-inactivated mutant (glk mutant) grew with maltose as the sole carbon source, with no residual glucokinase activity. This left a phosphoenolpyruvate-dependent phosphotransferase system (PTS) as the only candidate pathway for the phosphorylation of glucose in its transport as a substrate. Our hypothesis was that intracellular glucose derived from maltose mediated by the MalQ protein was released into the extracellular environment, and that such glucose was transported back into the cells by a PTS. The mannose PTS encoded by the manL, manM, and manN genes transports glucose into cells as a high affinity system with concomitant phosphorylation. The purpose of this study was to investigate extracellular glucose by using an enzyme-linked photometrical method, monitoring absorbance changes at 340 nm in supernatant of S. mutans cells. A significant amount of glucose was detected in the extracellular fluid of a glk, manLM double mutant. These results suggest that the glk and manLMN genes participate in maltose catabolism in this organism. The significance of multiple metabolic pathways for important energy sources, including maltose, in the oral environment is discussed.
Cytokeratins (CK) are abundant in keratinized cells, particularly CK14 and CK19, which are expressed in stratified squamous epithelial cells. In this study, expression of CK14 and 19 was examined in human epithelial and dysplastic tissues. Surgical specimens from patients with clinically diagnosed oral leukoplakia or early cancer were stained with hematoxylin and eosin and classified into normal, low grade dysplasia (LGD), high grade dysplasia (HGD), or squamous cell carcinoma (SCC). The sections were examined by immunostaining and reverse transcription-polymerase chain reaction (RT-PCR) for CK14 and CK19. Expression and the results of RT-PCR for CK14 showed a decrease in the order of LGD, HGD, and SCC, whereas those of CK19 showed an increase in that order. These results suggest that decreased expression of CK14 and increased expression of CK19 serve as indicators of potential for malignant transformation.
We report bone augmentation for alveolar bone loss at the bottom of the nasal cavity in conjunction with simultaneous implant placement in the same operative field in the esthetic zone. The patient was a 33-year-old man who was referred to us requesting implant treatment after undergoing tooth extraction (#12) due to root fracture. An examination was performed using cone beam computed tomography (CT) and simulation software. The results indicated insufficient volume of labial bone for the requested procedure, especially at the planned site of the implant neck. Therefore, bone augmentation was performed at the apical site of the implant socket (alveolar bone at the bottom of the nasal cavity). Because the surgical line of the harvest site formed a trapezoidal shape, the procedure was named the “Trapezial Design Technique”. Assessment of complications (Barone & Covane classification), success (Albrektsson classification), and observation of labial bone using cone beam CT were performed postoperatively. No com-plications were observed at 27 months after prosthetic treatment. The implant and the tissue surrounding it were in a stable condition. This indicates that this procedure is effective in placing an implant with simultaneous bone augmentation in the esthetic zone.
The infratemporal fossa is bordered superiorly by the infratemporal surface of the greater wing of the sphenoid bone and part of the temporal bone; medially by the lateral plate of the pterygoid process of the sphenoid bone; and anteriorly by the posterior surface of the maxilla. As it is completely surrounded by bone, it is frequently difficult to determine whether an abscess is present by direct visual observation or palpation alone. We report an extremely rare case of an infratemporal fossa abscess arising from chronic maxillary osteomyelitis developing after extraction of a maxillary molar. Despite drainage during initial oral anti-inflammatory treatment, pus continued to drain from the wound over a long period of time. This drainage ended when the eroded bone of the maxillary tuberosity on the affected side was curetted in a secondary procedure. The harvested bone tissue exhibited histological findings of chronic osteomyelitis. This suggests that the route of infection involved acute transformation of maxillary osteomyelitis by odontogenic infection advancing posteriorly and superiorly.
Odontoblasts play an important role in the transduction of the sensory signals underlying dentinal pain. Transmembrane voltage-independent Ca2+ influx in odontoblasts has been well described. Voltage-dependent Ca2+ influx has also been reported, but its biophysical properties remain unclear. The aim of the present study was to investigate the desensitizing effect of voltage-dependent Ca2+ influx in rat odontoblasts by measuring depolarization-induced intracellular free Ca2+ concentrations ([Ca2+ ]i ). Odontoblasts on dental pulp slices from newborn rats were acutely isolated and [Ca2+ ]i measured by using fura-2 fluorescence. Repeated application of extracellular high-K+ solution (50 mM), which induces membrane depolarization-elicited repeated and transient increases in [Ca2+ ]i in the presence of extracellular Ca2+. Increases in depolarization-induced [Ca2+ ]i showed no significant desensitizing effect (p >0.05; Friedman test). These results suggest that odontoblasts express a voltage-dependent Ca2+ influx pathway with no desensitizing properties.