This article reviews the current situation of CBCT in terms of the indications, the exposure dose to the patient and its reduction, and quality assurance in the use of CBCT. Plenty of articles related to these topics including several guidelines based on the scientific evidence have been published and these cover essentials for consideration in these tasks. Such evidences are helpful for clinicians when considering the application of CBCT, and suggest that clinicians should keep abreast of recent advances in CBCT technology.
Since joining Showa University, I have been studying the regulatory mechanisms related to differentiation and functions of hard-tissue-constituting cells. Here I present two topics that have recently received out attention. The first is monocarboxylate transporter-1, a molecule involved in cellular energy metabolism, which controls the expression of phagocyte-type NADPH oxidase and cell death in chondrocytes. The other is lysine gingipain, a protease produced by Porphyromonas gingivalis that promotes osteoclast differentiation.
Streptococcus mutans uses two-component signal transduction systems (TCSs) to monitor and respond to the fluctuating pH levels to survive the human oral cavity. The TCSs modulate the expression of genes encoding products crucial to cell survival. CiaRH is one of TCSs that is thought to be responsible for the acid tolerance of this pathogen; however, the target molecules modulated by the CiaRH have been still unclear. In this study, we identified that a lipoprotein OpcC contributes to the acid tolerance of S. mutans. The opcC-deficient mutant showed higher acid sensitivity than the wild-type 109c. In addition, deletion of the gene encoding prolipoprotein diacylglyceryl transferase (Lgt) eliminated OpcC on the cell surface of S. mutans. These results suggest that OpcC is an acid-tolerance related lipoprotein that is lipid anchored in the cell membrane by Lgt. Relationship between opcC and CiaRH was assessed by transcriptional analysis of S. mutans in the acidic or neutral conditions. The opcC expression was increased in the wild type and ciaR mutant in the acidic environment. However, the opcC expression was not increased in the ciaH mutant by the acidic stress. These results suggest that acidic stress sensing by CiaH is essential for the increased expression of opcC. Collectively, S. mutans OpcC is an acid tolerance-related lipoprotein whose gene-expression is enhanced via CiaH by sensing the acidic stress. In this study, we clarify the partial mechanism mediating S. mutans survival in acidic environments by showing the link between CiaRH and OpcC.
To clarify 1) how the signal fading effect occurs and 2) the diagnostic quality of the signal fading image in caries diagnosis. The Digora Optime (Soredex, Helsinki, Finland) system was used. Aluminum step wedges of 1 to 10 mm thickness and 1-mm-thick lead were used. Exposed photo-stimulated phosphor imaging plates (PSP-IPs) were scanned at six different intervals: immediately, 3, 6, 24, 72, and 144 h. Two kinds of scanning modes were used: with and without auto enhancement correction (AEC). The gray value difference between the immediate and delayed scanning images in the same objective area was calculated as the signal fading effect value (FEV). Thirty extracted upper premolar teeth (carious: 42 surfaces) were used. Immediate, 3, 24, and 72 h delayed scan images were created. Four observers assessed them. The Friedman test was used for statistical analysis and statistical significance was p<0. 05. Analysis of the without AEC image revealed that the signal fading had the same gray value change. This change was not related to the initial gray value. In the processing of AEC, the middle part of the gray value tended to be more enhanced. Significant differences in gray value changes were observed after 3 h, but no statistically significant difference was seen in the caries diagnosis. The area under the receiver operating characteristic (ROC) curve (Az) from immediate, 3, 24, and 72 h delayed images was 0. 61±0. 17, 0. 56±0. 04, 0. 67±0. 04, and 0. 58±0. 06.
To avoid excessive excavation of carious dentin, we developed a caries-detecting agent composed of polypropylene glycol to stain caries-affected dentin. The purpose of this study was to evaluate the new agent by examining the characteristics of the dentin surface after removal of carious dentin. Eight extracted human teeth with dentin caries were used. The teeth were longitudinally sectioned through the center of the caries and micro Vickers hardness (MVH) was measured from the pulpal wall to the caries cavity every 200 μm. Carious dentin was then removed using a steel bur following Caries Check (Nishika, Yamaguchi, Japan) staining. After removal of the stained dentin, the MVH of the dentin was determined by observing the indentation on the dentin; the DIAGNOdent value (D-value) was measured using DIAGNOdent (Kavo, Biberach, Germany). Then a new caries-staining agent (Discover RED, Phoenix Dental, Inc., Fenton, MI, USA) was applied in the cavity, the stained dentin was removed, and the MVH and D-value were measured. Finally, such procedures were repeated using Caries Detector (Kuraray, Tokyo, Japan). After the final measurements, the microstructure of the dentin cavity wall was observed by scanning electron microscopy. The differences in the MVH and D-value between using Caries Detector and Discover RED were not significant. However, the differences in the MVH and D-value between the Caries Check and the other two methods were significant. Caries Check may be the most useful modality for the more precise excavation of carious dentin and preservation of sclerotic dentin.
With super aged society in Japan, the death rate from choking due to blockage of the oropharynx has increased; it is now greater than that from traffic accidents and it is believed that this rate will continue to increase. The shape and function of the oropharyngeal crossing with the respiratory tract are most influential in ensuring that food is carried from the oral cavity to the pharynx and the esophagus. We sought to clarify the changes in the shape and features of the oropharyngeal airway from teenagers to those in their 70 s. A total of 57 patients were grouped by age (teenagers, 20s, 30s, 40s, 50s, 60s and 70s), and all underwent cone beam computed tomography (CBCT) to measure the oropharynx volume, height, cross-sectional area, and length of the superior and inferior extremities. Kruskal-Wallis analysis indicated that the volume and height of the oropharynx did no significant difference among age groups, but there was a different tendency when cross-sectional areas of the superior and inferior extremities were compared between younger and older patients. Further, the shape of the inferior extremity was also different features between younger and older patients. In humans, the oropharyngeal airway plays an important role in carrying food through the esophagus and facilitating phonation. Ideally, it is important for this airway to maintain a constant volume and height. Recently, there has been an increase in the incidence of oropharyngeal airway blockage accidents among the elderly. Declines in feeding and swallowing functions and changes in the form of the oropharynx are major factors in these accidents.
Many aspects of the coordination of lip and mandibular movements in the process of eating have not yet been clarified. This time, aiming to objectively evaluate lip and mandibular movements when chewing, the movements of the corners of the mouth and the mandible during mastication were measured three-dimensionally and analyzed. The subjects were 20 healthy women with individual normal occlusion. The test food was a commercially-available biscuit with a weight of 1 g. With six measuring points set for the lips and pogonion, the movements at those measuring points were captured with two CCD cameras during mastication, and the resulting images were analyzed with a three-dimensional motion analysis system. The analysis result showed that X- and Z-axis movements occurred on the working-side corner of the mouth, with Z-axis movements preceding X-axis movements, while on the balancing-side corner of the mouth, X- and Z-axis movements occurred simultaneously. Data on the amount, time taken, and speed of movements measured at each anatomical landmark showed that the working-side corner of the mouth moved a greater distance at a faster pace and, therefore, in less time than that of the balancing-side corner of the mouth. This is conceivably due to the aforementioned differences in X- and Z-axis movements of the working-side and balancing-side corners of the mouth. Further comparisons and studies with expansion of the subjects to include children will be necessary.
We examined the effects of fructooligosaccharide (FOS) consumption on gastrectomy-evoked osteopenia in rats. Forty-two 35-day-old male Sprague Dawley rats were equally divided into two groups and a sham operation group or a total gastrectomy group was performed. Four weeks after each surgery, 14 rats were killed in each group (BaseSH and BaseGX groups). Thereafter, the remaining rats were equally divided into two sub-groups; with or without 7.5% FOS (1.35 g/day)-feeding (SH, SH+FOS, GX and GX+FOS groups) for six weeks. Backscattered electron images of the tibial cross-sections were taken to calculate the cortical bone area (CBA). The CBA in BaseGX rats was markedly decreased. Thereafter, FOS-feeding significantly counteracted this reduction, but not to the level seen in SH rats. These results suggest that FOS consumption partially restored osteopenia in cortical bone following the gastrectomy.