The primary aim of the present study was to compare efficiency in detecting suspected caries requiring observation (CO) and decayed teeth (DT) between dental explorers and Community Periodontal Index (CPI)-probes in school dental examinations and evaluate the effect of their respective use on Decayed, Missing, Filled Teeth (DMFT) Index scores. A total of 126 elementary and high school students were examined. All the clinical findings were obtained by a pair of trained dentists examining each student at routine annual school dental examinations. A dental explorer or CPI-probe and dental mirror were used for the examination. One dentist used the dental explorer, while the other used the CPI-probe. The choice of which instrument to use by the first dentist to examine the student was made at random. A comparison of the explorers and CPI-probes revealed that the numbers of patients and permanent teeth classified as CO were greater with the former in 6th-grade elementary and high school students (p<0.05). The Kappa value for CO and DT was 0.560 for 6th-grade elementary school and 0.846 for high school students. All DMFT scores were higher with the explorers than with the CPI-probes in the 6th-grade elementary school students. No significant difference was observed between the explorers and CPI-probes in any of the DMFT scores in any group, however. The present results indicate that as long as the low rate of caries in Japanese school children is maintained, the epidemiological data on this disease should not show any significant change if a CPI-probe is used instead of an explorer in school dental examinations.
Recently, new methods have been applied to increase velocity of tooth movement. A standard mean of tooth movement velocity remains to be established, however. Moreover, to our knowledge, no studies have investigated the effect of factors affecting this velocity. The aim of the present study was to investigate the effect of facial pattern on the mean velocity of canine retraction in selected cases of orthodontic treatment carried out at this hospital. A total of 112 patients with Angle Class I crowding treated with extraction of the bilateral maxillary and mandibular first premolars and a conventional edgewise bracket were selected at random. The canine retraction period was defined as that between the end of leveling and the beginning of anterior retraction, and was obtained from medical records. Calipers were used to measure how far the canine cusps moved between pre- and post-surgically on superimposed cephalometric tracings. The velocity of canine retraction was significantly slower in the maxilla of male patients with a brachyofacial pattern (p<0.01). Canine retraction is the longest stage of orthodontic treatment. Here, movement was slowest in the maxilla of male patients with a brachyofacial pattern. This indicates that treatment may take longer than average in male patients with a brachyofacial pattern, and that this should be explained prior to commencing such work.
As of fiscal year 2006, it became compulsory for all newly licensed dentists in Japan to undergo a year of practical training at one of the designated training facilities found throughout the country as part of their postgraduate programs. The goal of this training is for the trainees to acquire diagnostic and therapeutic skills. While officially trainees, they are nonetheless regarded as members of staff. Clinical training emphasizes improving both technical skills and theoretical knowledge. However, taking on such trainees is sometimes considered unprofitable, as work productivity is claimed to be low. The purpose of this study was to compare work outcomes and income generated between trainees and part-time dentists working at the Tokyo Dental College Suidobashi Hospital. The part-time dentists comprised clinical instructors and dentists responsible for outpatients. Postgraduate dental trainees also generally conduct dental treatment for outpatients. Therefore, part-time dentists were considered the most suitable for a control group. No significant difference was observed in the total number of patients seen by either group by the final term of clinical training. Furthermore, no significant difference was observed in insurance-based dental treatment unit income (insured care unit income) per patient between the two groups from the mid-term period of training onwards. These results suggest that, although the trainees were less efficient in terms of time taken to provide a diagnosis and treatment, their performance was almost equal when viewed from the viewpoint of insured care provided. Taken together, this suggests that time-related care efficiency must be increased and specific training policies and strategies developed to improve the work productivity of dental trainees.
The purpose of this study was to investigate which were the most important factors in determining the location of the main occluding area by comparing its site on the dental arch between patients treated with implant-supported prostheses and those with a shortened dental arch (SDA). Twenty-five patients with Eichner B1 occlusion were enrolled in the study. The molar region in each quadrant was always edentulous. Fifteen patients were treated with implant prostheses, while the remaining 10 patients had SDA. Each patient was instructed to clench a piece of temporary stopping in the occluding area that was preferably used during mastication. The main occluding area was determined by locating the tooth on which the temporary stopping rested during clenching. The main occluding area was located ipsilaterally to the edentulous side in the molar region more often in the implant patients than in the SDA patients. The results of the present study suggest that the most important factor in determining the main occluding area is the presence of bilateral rigid molar occlusal support.
Calcium deposited within a root canal due to exogenous stimuli may hamper root canal treatment. In endodontic treatment, an operating microscope allows the conditions within the root canal to be directly viewed and evaluated. This report describes a case in which an operating microscope was used to facilitate the excision of a calcified structure from within a root canal at an early stage in the treatment of an infection. An 18-year-old man was referred to our clinic due to suspected chronic suppurative apical periodontitis of the right maxillary central incisor. Periapical radiography confirmed the presence of a radioopaque structure inside the root canal that was likely to pose an obstacle to endodontic treatment. After opening the pulp chamber, an operating microscope was used to directly confirm the presence of the calcified structure in the root canal, which was removed using an ultrasonic tip. The infected root canal was treated using calcium hydroxide. Two months later, closure of the apical foramen as a result of calcification of the apical foramen was confirmed and the root canal filled. Using an operating microscope to directly view a structure posing an obstacle to root canal treatment made it possible to perform an excision while avoiding risks such as canal perforation.
Supernumerary teeth in the molar area are classified as paramolars or distomolars based on location. They occur frequently in the maxilla, but only rarely in the mandible. These teeth are frequently fused with adjacent teeth. When this occurs, the pulp cavities may also be connected. This makes diagnosis and planning of endodontic treatment extremely difficult. Here we report a case of a mandibular second molar fused with a paramolar, necessitating dental pulp treatment. Intraoral and panoramic radiographs were obtained for an evaluation and diagnosis. Although the images revealed a supernumerary tooth-like structure between the posterior area of the mandibular second molar and mandibular third molar, it was difficult to confirm the morphology of the tooth root apical area. Subsequent cone-beam computed tomography (CBCT) revealed that the supernumerary tooth-like structure was concrescent with the root apical area of the mandibular second molar. Based on these findings, the diagnosis was a fused mandibular second molar and paramolar with a concrescent supernumerary tooth. A 3-dimensional (3-D) printer was used to produce models based on the CBCT data to aid in treatment planning and explanation of the proposed procedures to the patient. These models allowed the complicated morphology involved to be clearly viewed, which facilitated a more precise diagnosis and better treatment planning than would otherwise have been possible. These technologies were useful in obtaining informed consent from the patient, promoting 3-D morphological understanding, and facilitating simulation of endodontic treatment.
Streptococcus mutans utilizes maltooligosaccharides, including maltose derived from human dietary starch. We recently reported that the glucose-phosphotransferase system (Glc-PTS) was also involved in the metabolism of glucose derived from intracellular maltooligosaccharides in S. mutans. The activity of the Glc-PTS was mediated by the mannose-(manLMN) and cellobiose-PTSs (celABRCD) in this organism. The purpose of this study was to identify which kind of glucose transporter was involved in this process. A celD, manLM, and glk triple mutant, cm6vU1, was constructed and its growth in maltose or glucose broth measured. When cm6vU1 cells were inoculated into a fresh glucose broth following prolonged incubation with glucose, their growth rate was greater than that in the initial inoculum. This suggested that an additional Glc-PTS was induced in these cells. To investigate this possibility, permeabilized S. mutans cells were constructed and Glc-PTS activity examined by photometrical assay method. Activity in the cells was higher in the secondary inocula than in the initial inocula. These results suggest that S. mutans possesses an additional as yet uncharacterized PTS transporter for glucose in addition to the mannose- and cellobiose-PTSs.