Influence of Lifestyle Factors on Risk of Dental Caries among Children Living in Urban China.

The prevalence of dental caries has been decreasing among kindergarten children in Shanghai, China, over recent years, although it still remains at an unacceptably high level. The purpose of this study was to identify which factors were important in providing oral health guidance and achieving further improvement in the oral health status of kindergarten children in urban China. A survey was conducted on dental caries in 128 Japanese and 368 Chinese kindergarten children and a questionnaire given to their parents/guardians on each child's lifestyle and dietary habits from birth to the present. Correlations between responses to each questionnaire item and the status of dental caries were statistically analyzed. The dft index score (p=0.0016), prevalence of dental caries (p=0.0002), and percentages of children with decayed (untreated caries-affected) teeth (p<0.0001) were significantly higher in the Chinese than in the Japanese children. Many differences were observed in lifestyle factors between the two groups. The percentage of parents failing to control the child's snacking habits between meals was higher in China, and weaning was significantly delayed in China compared with in Japan. These lifestyle factors were considered to be associated closely with the high risk of dental caries in Chinese kindergarten children. These findings indicate that oral health guidance for kindergarten children in Shanghai, China, should focus on control of dietary habits, including control of inter-meal snacking, and breastfeeding practices. The results of this study may help improve the status of dental caries among Chinese children.

Characterization of a potential ABC-type bacteriocin exporter protein from Treponema denticola.

BACKGROUND: Treponema denticola is strongly associated with the development of periodontal disease. Both synergistic and antagonistic effects are observed among bacterial species in the process of biofilm formation. Bacteriocin-related genes have not yet been fully characterized in periodontopathic bacteria. The aim of this study was to detect and characterize bacteriocin-associated proteins in T. denticola. METHODS: The whole genome sequence of T. denticola ATCC 35405 was screened with a Streptococcus mutans bacteriocin immunity protein (ImmA/Bip) sequence. The prevalence of homologous genes in T. denticola strains was then investigated by Southern blotting. Expression of the genes was evaluated by qRT-PCR. RESULTS: In the genome sequence of T. denticola, an amino acid sequence coded by the open reading frame TDE_0719 showed 26 % identity with the S. mutans ImmA. Furthermore, two protein sequences encoded by TDE_0425 and TDE_2431 in T. denticola ATCC 35405 showed ~40 % identity with that coded by TDE_0719. Therefore, TDE_0425, TDE_0719, and TDE_2431 were designated as tepA1, A2, and A3, respectively. Open reading frames showing similarity to the HlyD family of secretion proteins were detected downstream of tepA1, A2, and A3. They were designated as tepB1, B2, and B3, respectively. A gene harboring a bacteriocin-like signal sequence was detected upstream of tepA1. The prevalence of tepA1 and A2 differed among Treponema species. Susceptibility to chloramphenicol and ofloxacin was slightly decreased in a tepA2 mutant while that to kanamycin was increased. Expression of tepA3-B3 was increased in the tepA2 mutant. CONCLUSION: These results indicate that T. denticola ATCC 35405 has three potential bacteriocin export proteins and that the presence of these genes differs among the Treponema strains. TepA3-B3 of the corresponding proteins may be involved in resistance to chloramphenicol.

Dentilisin involvement in coaggregation between Treponema denticola and Tannerella forsythia.

Periodontitis arises from a biofilm consisting of gram-negative anaerobic rods and spirochetes. Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia, termed the Red complex, have been co-isolated with high frequency from chronic periodontitis lesions, and these microorganisms are thought to be major pathogens of the disease. Coaggregation is an important strategy in the colonization of dental plaque biofilm by these bacteria. In the present study, we investigated the coaggregation of T. denticola strains with T. forsythia ATCC 43037 by use of visual grading or spectrophotometry. T. denticola ATCC 35405 coaggregated with T. forsythia, reaching a plateau at approximately 60 min. This coaggregation was inhibited by heat treatment of T. denticola ATCC 35405, but not of T. forsythia. Disaccharides such as sucrose, maltose, and lactose inhibited coaggregation by approximately 50%. The coaggregation reaction varied among T. denticola strains. There was somewhat less coaggregation between T. denticola ATCC 33520 and T. forsythia than between T. denticola ATCC 35405 and T. forsythia, although this difference was not statistically significant; T. denticola ATCC 33521 showed a trace level of coaggregation with T. forsythia. The magnitude of coaggregation among the three T. denticola strains was proportional to their dentilisin activities. Inactivation of dentilisin abolished coaggregation activity, but inactivation of the major outer sheath protein did not. In addition, phenylmethylsulfonyl fluoride did not affect coaggregation. These results indicate that dentilisin is involved indirectly in the coaggregation between T. denticola and T. forsythia, because its proteolytic activity is not required, possibly via ligand maturation.

Longitudinal observation of developmental change in maxillary deciduous and permanent canines.

During the period of the growth and development of the dental arch, anterior-posterior and medial-lateral changes in the maxillary deciduous and permanent canines were longitudinally studied in children. A longitudinal series of dental casts were obtained from 50 children at 2-month intervals from the completion of deciduous dentition to the stable period of permanent dentition. Subjects were divided into two groups according to the arrangement of the permanent teeth: a normal dental arch group and a crowded dental arch group. The mesial and distal points of the deciduous and permanent canines and the most prominent points on the labial and lingual contours were observed longitudinally. The results indicated that the measurement points of the deciduous canines in the normal and crowded groups moved in the anterior and lateral direction. When the amount of movement in the normal group was compared to that in the crowded group, the normal group showed greater movement than the crowded group. The permanent canines in both groups moved in the anterior and medial directions. When the amount of movement in the normal group was compared to that in the crowded group, the normal group showed more anterior movement than the crowded group, and the crowded group showed more medial movement than the normal group. When the distal point of the permanent canine was compared with the point of the deciduous canine at the exfoliation period in the normal arch group, the permanent canine was in almost the same position or was in a more anterior position than the deciduous canine. In the crowded arch group, the permanent canine tended to drift posteriorly.

Functional expression of alpha 7 nicotinic acetylcholine receptors in human periodontal ligament fibroblasts and rat periodontal tissues.

Tobacco smoking is the main risk factor associated with chronic periodontitis, but the mechanisms that underlie this relationship are largely unknown. Recent reports proposed that nicotine plays an important role in tobacco-related morbidity by acting through the nicotinic acetylcholine receptors (nAChRs) expressed by non-neuronal cells. The aim of this study was to investigate whether alpha 7 nAChR was expressed in periodontal tissues and whether it functions by regulating IL-1 beta in the process of periodontitis. In vitro, human periodontal ligament (PDL) cells were cultured with 10(-12) M of nicotine and/or 10(-9) M of alpha-bungarotoxin (alpha-Btx), a alpha 7 nAChR antagonist. The expression of alpha 7 nAChR and IL-1 beta in PDL cells and the effects of nicotine/alpha-Btx administration on their expression were explored. In vivo, an experimental periodontitis rat model was established, and the effects of nicotine/alpha-Btx administration on expression of alpha 7 nAChR and development of periodontitis were evaluated. We found that alpha 7 nAChR was present in human PDL cells and rat periodontal tissues. The expressions of alpha 7 nAChR and IL-1 beta were significantly increased by nicotine administration, whereas alpha-Btx treatment partially suppressed these effects. This study was the first to demonstrate the functional expression of alpha 7 nAChR in human PDL cells and rat periodontal tissues. Our results may be pertinent to a better understanding of the relationships among smoking, nicotine, and periodontitis.

Nonlinear dynamical analysis of the effect by six stimuli on electroencephalogram.

The present study investigated the search by correlation dimension (D2) for the effect of six stimuli (sucrose, spearmint, gum-base chewing as a voluntary movement, and three combinations of these stimuli) on EEG findings. Twenty normal adult subjects received sucrose, spearmint oil, gum-base alone, and three combinations of these stimuli. EEG recordings were obtained while the subjects rested quietly with their eyes closed, as the following procedure: section I, 1 minute at rest; section II, first 5-minute recording (control record); session III, each stimulus affecting for 3 minutes; session IV, 1 minute at rest; session V, 5-minute recording (poststimulus record). The EEG activity was filtered with a 0.5 Hz high pass and a 30 Hz low pass filter. The final data (epoch) for analysis were selected from all data by our epoch inducing system, and D2 was calculated using a novel analytical program. D2 was found to increase after subjects inhaled spearmint. In contrast, D2 decreased after subject's chewed gum-base and after the combination stimuli with chewing. Furthermore, the D2 change observed after each stimulus was similar to the observed D2 changes in the theta band. These findings suggest that D2 expressed the change in EEG as a brain response after each stimulus. It was also demonstrated that the change of EEG complexity as a brain response to stimulation is related to theta rhythm that might be able to produce at the cortical limbic area. We confirmed that the change observed in the complexity in response to which the chewing stimulus relates in our present study is the model that best fits that theory of the change on complexity suggested by Stam CJ.

Longitudinal study on influence of prolonged non-nutritive sucking habits on dental caries in Japanese children from 1.5 to 3 years of age.

The purpose of the present study was to investigate the relationship between infant sucking habits and the prevalence of caries in Japanese preschool children.The study was designed as a prospective, longitudinal study starting with 592 children aged 18 months. Information on sucking habits and patterns of feeding was collected from parents in the form of a questionnaire. Children who continued breastor bottle-feeding at 18 months of age were eliminated prior to the evaluations. The children were divided into 3 groups according to their sucking habits at 18 months of age: Group 1: children with a finger-sucking habit (n=151); Group 2: children who used a pacifier (n=45) and Group 3: children with no oral habit (n=205). Clinical examinations were carried out by one of the authors.Mean dft and prevalence of caries were not statistically significant among the 3 groups at 18 months of age. However, only 10.6% of the children in Group 1 exhibited caries at 36 months of age, compared with 17.1% in Group 3 and 24.4% in Group 2. Group 1 children showed the smallest mean dft at 0.30 among the 3 groups at 36 months of age, and those in Group 2 showed 1.18; the difference was statistically significant (p<0.01).The results suggest that children with a finger-sucking habit are more likely to be free of caries by the age of 3. However, use of pacifier at 18 months of age is a potential risk factor for the development of dental caries in children.

Awareness of malalignment and malocclusion in children and their guardians.

We conducted a survey on the awareness of abnormalities of dentition and occlusion in 1,904 children (0-15 years old) and their guardians (parents, grandmothers, grandfathers and siblings) on their initial visit to the Department of Pediatric Dentistry, Chiba Hospital, Tokyo Dental College. The location and type of abnormality for which the children and their guardians most commonly sought treatment were crowding of the upper and lower anterior teeth and inverted occlusion. The most common initial triggers for concern were "guardians noticed abnormalities themselves". It seems logical that where malocclusions that children and guardians can easily notice for themselves are present, they are likely to make an early visit to a clinic in the hope of improving the abnormality. We suggest that further effect is made to educate guardians of children with abnormalities of dentition and occlusion on the importance of obtaining treatment.

Clinical survey on type of restoration in deciduous teeth.

This study was conducted in 533 children with 1,634 treated teeth who visited the Pediatric Dentistry Department at the Chiba Hospital of Tokyo Dental College between January and December, 2003. Restorations on deciduous tooth were categorized by age of patient and tooth type. The following observations were made: Children aged 4 (17.9%) visited the clinic most frequently and this group had the highest number of deciduous restorations (21.3%). Among the 1,634 deciduous teeth restored, metal inlays were provided in 29.4% of total teeth restored, composite resin restorations in 27.2%, stainless-steel crowns in 25.7%, composite resin full crowns in 7.7%, glass-ionomer cement restorations in 6.6%, and amalgam restorations in 3.4%. By age, composite resin was most frequently used in children aged 1 to 3. In children aged 5 to 9, metal inlay was most frequently used. Those aged 4 received mostly stainless-steel crowns. Composite resin restorations were used mostly in anterior deciduous teeth, and metal inlays mostly in deciduous molars. Previous research indicated an increasing trend towards composite resin restorations and composite resin full crowns. The present study also confirmed such a trend. While the use of metal inlays and stainless-steel crowns tended to increase until 1987, the present study indicated a trend to decrease.

CT image applications for pre-surgical assessment and surgical pre-planning in Pediatric Dentistry.

In this study we focused on dental anomalies peculiar to children and investigated how 3D-surgical planning and simulation could be applied to each case. This study included 3 patients (2 female and 1 male, 8 to 12 years). The CT imaging was performed via a SOMATOM Plus4. From the resulting data, an image of the tooth and bone was rendered using image analysis software Amira 3.1 which was then used to reconstruct three-dimensional images. The reconstructed 3D images were imported to 3D modeling software, which provided the basis for the surgical simulations. From these results, we were able to gain important insights that helped shape the planning of the surgical operation. Furthermore we consider that these findings would be useful for the patient when taking them through the process of obtaining informed consent.

Dental care for physically or mentally challenged at public dental clinics.

Recently, local administration bureaus have established a number of dental clinics and centers for the physically or mentally challenged (PMC) in collaboration with local dental associations. The aim of this study was to investigate dental treatment and general supportive care for the PMC in dental clinics in Tokyo. A dental clinic for the PMC located in northwestern Tokyo in a district with a population of about 680,000 was selected for the study. The variables studied based on dental records included total number of patients, type of disability, medical history, systemic condition, age, treatment regimen and type of general supportive care. The largest group of new patients was under 9 years of age. The highest total number of patients visiting the clinic belonged to the 60-69-year-olds group and the 70-79-year-olds group. We also investigated type of disability in patients treated under intravenous sedation at time of dental treatment. The most common condition was dementia resulting from Alzheimer's disease (42.74%), autism, cerebral palsy or mental retardation, in descending order. The percentage of patients referred from other medical institutions was 17.4%, including those from private dental clinics and Dental University Hospitals. Type of disability in patients transferred from other medical institutions included developmental disorders (28.2%), senile defects (26.9%), chronic and psychiatric diseases (44.9%). The number of patients who located and visited the clinic by themselves greatly exceeded the number transferred by request. This suggests that a permanent system should be put in place offering public specialized dental clinics where the PMC many obtain treatment.

The relation between tooth shape ratio and incisor arrangement in Japanese children.

To investigate whether the relationship between tooth shape ratio and incisor arrangement proposed by Peck et al. in 1972 was applicable to Japanese children, we compared two groups, one with normal permanent dentition and another with crowded permanent dentition, using chronologically constructed plaster dentition models. Tooth shape ratio was obtained by dividing the incisor mesio-distal width by the labio-lingual width and then multiplying the result by 100. The results revealed a significant difference in the coronal mesio-distal diameter of the incisors between the two groups, but the other items showed no significant differences, suggesting no clear relationship between tooth shape ratio and incisor arrangement. That was, our results suggest that there is no clear relationship between tooth shape ratio of the mandibular incisors and arrangement of the permanent incisors in Japanese children.

Two cases with supernumerary teeth in lower incisor region.

Abnormalities in number of teeth are occasionally noted in clinical cases. Many theories have been proposed as regards the causes of the occurrence of supernumerary teeth, including atavism theory, mechanical tooth germ separation theory, tissue induction theory, and dental laminar morphological disturbance theory. However, none of these theories alone offers a sufficient explanation for this phenomenon. The incidence of supernumerary permanent teeth is approximately 1-3%. These are the maxillary anterior teeth, the maxillary molars, and the maxillo-mandibular premolars in terms of descending order of site of occurrence. On the other hand, incidence in the mandibular anterior tooth area, of which there have been few detailed reports, is about 0.01%, a markedly low value. In this paper, we report two rare cases of supernumerary teeth in the mandibular incisor area. We discuss their etiology and orthodontic treatment, and detail a differential diagnosis between the normal and supernumerary teeth. We found that it was difficult to establish a clear etiology and differentiation between the normal and supernumerary teeth.

Longitudinal study of prolonged breast- or bottle-feeding on dental caries in Japanese children.

The aim of this investigation was to study the effects of prolonged breast- or bottle-feeding on dental caries in Japanese infants. This longitudinal study was conducted by means of a questionnaire and clinical examination of 592 children at 18 months, 2 years and 3 years of age. The children were divided into three groups: 1) children still being breast-fed at 18 months of age (n=42); 2) children still being bottle-fed at 18 months of age (n=45); and 3) children weaned off of breast- or bottle-feeding and with no nonnutritive-sucking habits at 18 months of age (n=205). Results showed that breast-feeding at 18 months of age produced many significant differences to the control children, including a higher prevalence of caries and higher number of dft. However, no significant differences were observed between bottle-fed and control children. In conclusion, our results suggest that prolonged breast-feeding at an early age before primary dentition has fully erupted is a risk factor for dental caries. Therefore, breast-fed children need to be monitored more closely, and aggressive methods of preventive care need to be instituted. It is also important to identify factors related to dental caries among breastfed children as soon as possible, and develop effective preventive programs.

Characteristics of breast-fed children with nursing caries.

The aim of this study was to investigate the characteristics and risk factors of prolonged breast-feeding in children. A total of 105 children aged 18 months were screened for ongoing breast-feeding at a public health center. Of these, 105 children were selected for a more comprehensive examination, involving investigation of dietary, tooth-brushing habits and oral hygiene. The children were examined again, and initial and manifest caries were recorded at 24 months of age. As a result, 20 (19.0%) of the 105 children had caries at 24 months of age. Logistic regression analysis revealed an association between caries and bedtime breast-feeding (p=0.003). Oral hygiene at 18 months of age was also correlated with caries (p=0.015). It was concluded that reducing the frequency of feeding, early establishment of good oral hygiene habits and also regular visits to the dentist are essential in preventing nursing caries in prolonged breast-fed children.

Clinical validity of the interactive and low-dose three-dimensional dento-alveolar imaging system, tuned-aperture computed tomography.

Based on technical studies and clinical examinations, the clinical value of a new three-dimensional dento-alveolar imaging system, Tuned-Aperture Computed Tomography (TACT), were examined for dental applications. TACT is a conventional and low-cost tomosynthesis method in which the benefit of digitization is fully utilized. The clinical information yield of TACT has been examined for the detection of dental caries, periodontal defects and radicular fractures, and also for the pre-surgical assessment of implant placement and impacted teeth. In this article, we introduce basic TACT technology, review the literature pertaining to in vitro and in vivo studies, and describe the outline of our study of TACT to determine its clinical value in the assessment of impacted maxillary teeth.

A follow-up study on three caries activity tests.

The purpose of this research was to study the efficacy of three CAT's (Dentocult SM, Dentocult LB and Dentobuff Strip) in revealing caries condition and predicting caries progress, and provide a reference for application by comparing the three tests. Oral condition and results of the three CAT's of 82 children aged 3 to 4 were recorded and followed up. The examination was checked again two years later. The caries incidence, dft and CSI data from the two examinations were analyzed statistically. The results were that each Dentocult SM degree showed significant variances in incidence rate, as did the dft and CSI results in the second examination. The dft and CSI of both examinations exhibited a high degree of statistical significance. The same may be said of the Dentocult LB findings for the two years. No noticeable variances in caries incidence rate, dft and CSI from the Dentobuff Strip test were observed in both years' study, nor was there any statistical significance drawn from the findings, except for those of the second exam. No gender differences were observed in the distribution by degree with the three CATs The conclusion is that Dentocult SM is the best of the three tests for the diagnosis of the presence of caries and prognosis of its progress, Dentocult LB is second best whereas the Dentobuff Strip shows no detection capability. The findings serve as an application reference.

Diagnostic value of tuned-aperture computed tomography versus conventional dentoalveolar imaging in assessment of impacted teeth.

OBJECTIVE: This clinical study compares the diagnostic value of interactive 3-dimensional tuned-aperture computed tomography (TACT) with conventional dentoalveolar radiographic examinations of impacted maxillary incisors. STUDY DESIGN: TACT was compared variously with conventional intraoral, occlusal, rotational panoramic, and lateral cephalographic examinations. Sixteen dentists independently evaluated the clarity of anatomic structures of impacted anterior maxillary teeth and surrounding tissues. Estimation of confidence in clinical assessment of the patient was made together with a determination of the diagnostic potential of the studied modalities for altering treatment plans. RESULTS: TACT was found to significantly improve depiction of the buccal/palatal position of the impacted tooth and its relationship with adjacent teeth (P < .0001) irrespective of the availability of lateral cephalograms. Subjective assessments for clinical decision making approximated a 10% increase in confidence ratings with TACT. The added diagnostic value with TACT varied from case to case. CONCLUSIONS: The interactive 3-dimensional TACT display was perceived to be more informative for assessing impacted teeth and their relation to surrounding tissues than conventional methods in some cases but not in others. TACT altered treatment-option selection in some instances.