Glucocorticoids are used for treatment of a variety of diseases, although they are also known to have an effect on skeletal growth and induce osteoporosis. The aim of this study was to investigate whether exposure to prednisolone had an effect on craniofacial bone growth and the internal bone structure in young rats. Twenty 5-week-old growing male rats were divided into two equal groups. Prednisolone at 30 mg/kg/day (prednisolone group) or no drug (control group) was administered orally on alternate days for 6 weeks. Thereafter, growth of the total skull, neurocranium, maxilla, and mandible was determined on lateral cephalograms, while cortical bone density and strength strain index (SSI) of the femur diaphysis and mandible were determined using peripheral quantitative computed tomography (pQCT). In addition, the femur length was measured. In the prednisolone group, total body weight, femur length, mandibular corpus length and height, and coronoid process height were reduced. No effects of prednisolone administration on cortical bone density of the femur and mandible were detected, however, the SSI values, cortical bone cross-sectional area, and mineral content of the femur and mandible, and cortical thickness and periosteal circumference of the femur in the prednisolone group were significantly lower when compared with the control group. The findings indicate that glucocorticoid administration decreases longitudinal and mandibular bone growth, quality, and strength in growing rats, whereas it has no significant effect on cortical bone density.
The purpose of this study was to evaluate the effects of bovine lactoferrin on acid fermentation and enamel demineralization using Streptococcus mutans in a culture system and an artificial mouth model system. The antibacterial activity of bovine lactoferrin (bLF) against S.mutans was analyzed by a radial diffusion assay. In the culture system, the effect of bLF on the synthesis and adherence of water insoluble glucan (WIG) and the adherence of S.mutans to a glass surface was examined by a batch culture. In the artificial mouth model system, cell suspension of S.mutans, heart infusion broth supplemented with sucrose, and PBS or lactoferrin solution were supplied separately and constantly for 21 hours. The following parameters were determined for evaluation: the amount of artificial biofilm, the changes in pH underneath the biofilm; and the changes in enamel microhardness measured by a Vicker’s hardness tester. The antibacterial activity of bLF against S.mutans was observed. The amounts of bacterial cells in the total adherent fractions were inhibited by bLF in a dose dependent manner. The amounts of WIG in a firm-adherent fraction were significantly inhibited by 0.1-1.0% bLF. The changes in microhardness on enamel slabs in the bLF group (2.4±0.8) showed significantly less hardness reduction than those in the control group (22.3±2.5) (P < 0.001). The artificial biofilm accumulation was not reduced by bLF. The results of this study suggest that bLF might have inhibitory effects against acid fermentation and demineralization of enamel by S.mutans.
INTRODUCTION: Methicillin-resistant Staphylococcus aureus (MRSA) is a major pathogen causing nosocomial infections. To control nosocomial infection in a dental hospital, periodical surveillance of MRSA from the oral cavity is very important. Furthermore, this surveillance might reveal any alteration of the incidence of MRSA among healthy children in a particular area, because many children having no systemic disease except for dental problems come to dental offices. METHODS: Totally 741 children were participated in the present study; 307 in 1987-88, 103 in 1992-93, 129 in 1997-98 and 202 in 2002-2003. S.aureus was isolated from the tongues of children without systemic diseases. All isolates were investigated for coagulase types and susceptibilities to five antibiotics. RESULTS: S.aureus was isolated from 33-44% of children during the examination period. The incidence of MRSA was maximal in 1992-93, and then constant at around 3%. MRSA that have type II or III coagulase were relatively dominant. CONCLUSION: Although outbreaks of MRSA in Japan was decreased in the early 90’s, more than 3% of children without particular risks are considered positive for MRSA.
Apatite is considered to be effective for bone regeneration when it contains calcium carbonate and β-TCP. In the present study, we made 3 different apatite preparations, hydroxyapatite, hydroxyapatite containing calcium carbonate, and hydroxyapatite containing β-TCP, using spark plasma sintering and compared their abilities for osteoinduction. For elucidation of bone regeneration, evaluations are generally made after euthanasia of experimental animals. However, the present R_mCT® procedure allowed such evaluations while the animals were alive. Our results showed that sintered HAP containing β-TCP was more effective for guided bone regeneration than the other test materials.
We analyzed the distribution of 6 periodontal bacteria (Porphyromonas gingivalis, Prevotella nigrescens, Prevotella intermedia, Eikenella corrodens, Actinobacillus actinomycetemcomitans and Capnocytophaga sputigena) in dental plaque materials from 227 children (3-6 years old). The plaque materials were collected from all erupted teeth sites using a sterile toothbrush. Chromosomal DNA was extracted from each plaque sample, followed by a polymerase chain reaction with species-specific sets of primers. Standard strains of 6 bacteria were used as controls. Total detection rate of P.gingivalis, P.nigrescens, P.intermedia, E.corrodens, A.actinomycetemcomitans and C.sputigena were 5.3%, 47.1%, 8.4%, 83.7%, 83.3% and 81.1%, respectively. E.corrodens, C.sputigena and A.actinomycetemcomitans were very frequently detected at all ages. On the other hand, P.gingivalis and P.intermedia were detected less frequently. Detection rate of P.nigrescens, E.corrodens and C.sputigena increased with age. The average detection number for each age group increased with age (2.63, 2.98, 3.43 and 3.45 for age 3, 4, 5 and 6, respectively). The number of bacterial species in the plaque materials increased with age as well. Our results indicate that P.nigrescens, E.corrodens, A.actinomycetemcomitans and C.sputigena are established quite early in childhood, these bacteria increase with age in the oral cavity.
PURPOSE: In this study, we measured the vibration caused during dental treatment by an air turbine handpiece and a micro motor handpiece. We then analyzed the obtained data to develop a method for noise cancellation of such vibration during the treatment of tooth decay. We herein describe the audio characteristics of bone conduction sound made by teeth during dental treatment. We measure vibration sounds of an air turbine handpiece and a micro motor handpiece transmitted from teeth to the middle and/or inner ear and obtain its bone conduction characteristics for reducing uncomfortable dental treatment sounds using active noise control technique in the future. METHODS: First, we measure the frequency characteristics of both acoustic sounds and vibration sounds of two dental handpieces in a special treatment room. Second, we measure the frequency characteristics of bone conduction from teeth to the middle and/or inter ear by actuating a tooth with pure tones of several frequencies in an anechoic chamber. RESULTS: The basic rotational frequency of an air turbine head tip with no-load was about 5,500 Hz. A decline of the rotational frequency was confirmed at the turbine head when the bar came in contact with the tooth, and it was proven that the tooth received the effect of the vibration, when the head made contact with the tooth. The results showed that the micro motor handpiece speed varied from a low of 140 to 210 Hz to a medium speed of 280 Hz and a high speed of 700 to 770 Hz. These results were higher than manufacturer’s specifications of micro motor handpiece. The results of the bone conduction amplitude-frequency characteristics were the best audible amplitude-frequency was near 2,000 Hz in the upper and lower left central incisors.
A case of dense bone island (DBI) in the mandible is presented. A 10-year-1-month-old (10Y1M) girl came to our clinic for dental caries treatment. Radiographic examinations incidentally found an isolated round mass with uniform radiopacity in the region below the mandibular left canine and first premolar, which was diagnosed as a DBI. The patient also had an anterior crossbite and was referred to an orthodontic specialist. Although the orthodontist anticipated that the DBI might cause some problems with tooth movement, there were no specific complications encountered and treatment was completed. Thereafter, periodical examinations were carried out for approximately 8 years from the first visit and there were no adverse condition seen in the affected area. Further, orthopantomographic examinations were conducted approximately every 3 years to monitor the size and radiodensity of the lesion. The lesion expanded by approximately 10% up to the age of 15Y2M, after which it was reduced in size at the age of 18Y3M to become approximately 10% smaller as compared to that at the first visit. Further, radiopacity increased from the first visit to the age of 12Y9M, and then was decreased at the ages of 15Y2M and 18Y3M.
A scissors bite is one of the more unusual malocclusions in primary dentition. The purpose of this report is to describe the unilateral scissors bite in primary dentition and the treatment outcome following the use of constriction appliances. A 5-year, 5-month-old boy developed a scissors bite in the left molar region due to the extended width of the maxillary dental arch. Two types of appliances were used to reduce the width of the maxillary dental arch; one was a removable type modified from a conventional expansion plate, and the other was a fixed type modified from a quad-helix appliance. The left maxillary primary molars were able to bite normally after the treatment using both appliances. As a result, the left first molars also could be guided to a normal occlusion and prevented from becoming a scissors bite. We suggest that improvement of the scissors bite in the primary dentition stage can prevent subsequent malocclusions in permanent dentition.
A case of supernumerary primary and permanent canines is presented. A 9Y4M-old boy was referred to our clinic for consultation regarding a maxillary supernumerary primary canine. An oral examination showed 2 primary canines with a similar morphology between the maxillary left lateral incisor and first primary molar. The primary canine in the opposite quadrant had the appearance of a fused-tooth, with composite resin restoration seen in the border. Orthopantomography revealed that permanent successors were present for each primary tooth in the maxillary left region, whereas only a single permanent canine was developing in the opposite quadrant. The 2 primary canines in the maxillary left region were extracted at 9Y4M. The mesially located permanent canine emerged into the oral cavity at 10Y1M and was extracted at 10Y9M. At 12Y2M, the other permanent canine located in the distal position had nearly reached the occlusal plane and the maxillary right permanent canine had arrived at the occlusal plane. Dental age was evaluated by assessing the tooth formation stages in 4 orthopantomographs taken between 8Y5M and 12Y2M, and found to be nearly the same as chronological age. However, the dental ages of the maxillary left permanent canine that had erupted earlier than the one located distally and of the left permanent canine were approximately 1 year behind chronological age. In addition, the dental age of the left permanent canine located distally was 2.5 years behind until the patient reached the age of 10Y9M, after which tooth development was accelerated following extraction of the mesially located permanent tooth.
The Nagano Prefecture health promotion program “Health Grade Up Nagano 21” contains specific goals for dental health. These goals were evaluated in 2004, the middle the health promotion project period. Concerning the program’s main goals, the proportion of 3-year-old children without caries of deciduous teeth improved from 63.6% (baseline) to 71.4% in 2004. DMFT index at 12 years old fell from 2.3 (baseline) to 1.6 in 2004. Thus, the main targets generally improved, although certain areas require further improvement. For infants, we strongly advocate that parents refrain from giving sugary foods between meals. For school-aged children, it is necessary to provide personal guidance about how to clean the teeth and oral cavity and to stress the importance of the fluoride application program. For adults, we need to further encourage periodic dental health check-ups, and it is also necessary to cooperate with industrial health programs on this matter. It is important for us to develop a plan to improve these areas.
In pediatric dentistry, it is important to continue periodical examinations after the initial treatment as the child continues to grow and develop, and a recall system used for patient follow-up is crucial for effective treatment by pediatric dentists. We developed our own recall system and have used it for more than 25 years. In this study, we evaluated clinical parameters for dental caries and periodontal disease in selected patients, and analyzed the correlation between them and the number of consecutive years each patient participated in recall examinations. The subjects were 9-, 12-, and 15-year-old children who came to our clinic for a periodical examination in the summer of 2005, in whom we analyzed several indices of dental caries and focused on their relationship to number of years of follow-up. There were no significant differences between the number of consecutive years and plaque index among the 3 age groups, though a negative correlation tendency was found in the 15-year-old group. Similar results were found between number of years and the rate of DFT. However, there was a significantly negative correlation between the number of consecutive years of follow-up and DFT scores for first permanent molars in our patients. Our recall system for follow-up examinations, which include brushing practice, diet consultation, and caries preventive treatment (application of fluoride and fissure sealant), was shown to be effective for maintaining the oral health of our pediatric dental patients.