Microbiomes of colored dental biofilms in children with or without severe caries experience.

BACKGROUND: Biofilm coloration can compromise maturation and increase the risk of oral disease in adulthood, though children with colored biofilm do not always demonstrate a poor oral health status. AIM: The microbial compositions of colored and white biofilms in children were compared. DESIGN: Thirty-two dental biofilm samples from 16 children (age < 13 years) were analyzed using 16S rRNA pyrosequencing, then the subjects were divided into severe caries and healthy (caries-free) groups. Correlations between microbiomes and oral health status were also examined. RESULTS: Phylogenetic analysis revealed no distinctly different patterns between colored and white biofilms. In the severe caries group, genus Actinomyces, Cardiobacterium, Kingella, Lautropia, and Veillonella, and family Neisseriaceae were detected, though abundance was significantly different between colored and white biofilm specimens, in contrast to the healthy group. In addition, five colored biofilm samples from the severe caries group contained greater than 15% Actinomyces, which led us to consider that genus to be possibly associated with formation of colored biofilm in children. CONCLUSIONS: Our findings indicate that differences in bacterial composition between colored and white biofilms are higher in individuals with severe caries. Additional research may reveal the significance of colored dental biofilm in children.

Treatment of Child with Four Lost Maxillary Incisors due to Traffic Injury.

Tooth injury is frequently encountered in pediatric clinical practice. A clinician may be requested to not only respond at the time of injury, but also properly diagnose how such injury will affect the teeth and dentition. Here, we present a case of a child who lost 4 bilateral maxillary incisors due to a traffic accident, and in whom marked mesial inclination of the bilateral maxillary canines and bilateral maxillary first premolars would subsequently occur. Dental management was provided over an extended period. The boy, aged 9 years 11 months, visited our department with the chief complaint of premature loss of 4 bilateral maxillary incisors and eating disturbance associated with the loss of these teeth. Initially, a denture was fitted. The bilateral maxillary canines subsequently demonstrated marked mesial inclination, however, and erupted from an area equivalent to that of the bilateral central incisors. The bilateral maxillary first premolars also showed mesial inclination and rotation. Taking esthetics into consideration, a Nance holding arch with resin buttons that extended to the maxillary incisors and attached to artificial teeth was used. This appliance was also equipped with a retracting hook, and the bilateral maxillary canines were moved downward and distally. Presently, the removable partial denture is worn for the purposes of retention, esthetics, and mastication. Long-term oral management will be necessary. Therefore, final prosthetic treatment for the missing maxillary incisors is planned for when the patient reaches adulthood.

Identification, characterization, and expression of dentin matrix protein 1 gene in Xenopus laevis.

Dentin matrix protein 1 (DMP1) is an acidic extracellular matrix protein expressed mainly in bone and dentin, and is a member of the small integrin-binding ligand N-linked glycoprotein (SIBLING) family. The DMP1 gene, however, appears to evolve rapidly in comparison with other SIBLING genes, even though such functionally important molecules usually evolve more slowly than less important ones. The purpose of this study was to identify and characterize an ortholog of the DMP1 gene in an amphibian (Xenopus laevis; X. laevis) to clarify molecular evolutionary alterations in DMP1 associated with calcified tissues in tetrapods. Furthermore, we analyzed the mRNA expression of this gene to elucidate its functional change in bone and developing tooth germ in comparison with amniote DMP1s. The similarities of the deduced amino acid sequence of X. laevis DMP1 to that of the corresponding amniote proteins were low, although they did share several unique features specific to DMP1 and have similar properties. Expression of X. laevis DMP1 mRNA was predominant in osteocytes and odontoblasts, but only transiently observed in ameloblasts, as in amniotes. These results suggest that DMP1 has conserved several functions during tetrapod evolution. This indicates that continuity of biochemical properties has been more important in maintaining DMP1 functionality than that of the sequence of amino acid residues, which has undergone change over the course of molecular evolution.

Serotype distribution of Streptococcus mutans a pathogen of dental caries in cardiovascular specimens from Japanese patients.

The involvement of oral bacteria in the pathogenesis of cardiovascular disease has been studied, with Streptococcus mutans, a pathogen of dental caries, detected in cardiovascular lesions at a high frequency. However, no information is available regarding the properties of S. mutans detected in those lesions. Heart valve specimens were collected from 52 patients and atheromatous plaque specimens from 50 patients, all of whom underwent cardiovascular operations, and dental plaque specimens were taken from 41 of those subjects prior to surgery. Furthermore, saliva samples were taken from 73 sets of healthy mothers (n=73) and their healthy children (n=78). Bacterial DNA was extracted from all specimens, then analysed by PCR with S. mutans-specific and serotype-specific primer sets. The detection rates of S. mutans in the heart valve and atheromatous plaque specimens were 63 and 64 %, respectively. Non-c serotypes were identified with a significantly higher frequency in both cardiovascular and dental plaque samples from the subjects who underwent surgery as compared to serotype c, which was detected in 70-75 % of the samples from the healthy subjects. The serotype distribution in cardiovascular patients was significantly different from that in healthy subjects, suggesting that S. mutans serotype may be related to cardiovascular disease.