Caries and periodontitis are major oral diseases, both widespread and serious. Caries is thought to be caused by multifactorial, lifestyle-related factors as well as the genetic background of the patient. However, little is known about relevant genetic factors. Since the quality and quantity of enamel plays a direct role in the susceptibility to caries, we set out our quest for genetic factors from the two proteins crucial to the formation of dental enamel: amelogenin and enamelin. We isolated genomic DNAs from lingual mucosal cells derived from healthy and caries subjects, and examined the frequency of single nucleotide polymorphisms (SNPs) by the polymerase chain reactionrestriction fragment length polymorphism (PCR-RFLP) method. We focused on the SNPs of the amelogenin gene (AMELX) at positions ‫782ם‬ and ‫225ם‬ (in both cases, a C to T substitution), and on position ‫2542ם‬ position of the enamelin gene (ENAM; here, too, a C to T substitution). The subjects were all of Japanese extraction, of which 67 individuals served as healthy controls and 80 patients with severe caries served as test subjects. The occurrence of the substitutions at AMELX(‫,)782ם‬ ‫)225ם(‬ and ENAM(‫)2542ם‬ were 12.2, 0.0 and 11.9% in the control group, and 2.5, 0.0 and 5.0% in the caries group, respectively. The P-values for the statistical frequency of SNPs for AMELX(‫)782ם‬ and ENAM(‫)2542ם‬ were 0.142 and 0.143, respectively. Our data suggest that there was no significant association between the SNPs of those genes and caries susceptibility in the Japanese pediatric population.reported that levels of ␣-defensin 1-3 (an antimicrobial peptides from saliva) were significantly higher in children with no caries than in those with caries, in contrast to cathelicidin LL37 and ␤-defensin 3 3) . Thus, dental caries is a multifactorial disease. Amelogenins are extracellular matrix proteins which make up 90% of the enamel organic matrix. They are expressed specifically in the developing tooth bud and cleaved in a regulated process during enamel maturation 4,5) . Amelogenin proteins have been implicated in the control of enamel crystal growth, but their precise role has not yet been defined 6) . Amelogenin proteins also inhibit apatite

Histatins are salivary proteins found and expressed in human salivary glands. They play a role in the non-immune system of antimicrobial defense, for instance, against Candida albicans. The transcriptional regulatory sequences of the histatin gene, HIS1, have remained obscure for a long time. Here, we cloned the putative promoter from human genomic DNA and tested it in a luciferase reporter system. This promoter is much more active in salivary gland cells than in other cell types. Analysis of deletion mutants revealed that the region encompassing -2254 to -1748 is a strong positive transcriptional element, and its functional core sequence (termed HTN27 box) works in correct and reverse orientations in synergy with downstream sequences, the region spanning -680 to +28 and a proximal promoter. The plus single-stranded HTN27 box is specifically bound by a 100 kDa protein that is present in HSG cells, but not in HeLa cells. These findings indicate that the regulation of the histatin gene expression may be intricate, and it seems to have a cell-type preference in the salivary gland cells.

Caries is a major oral disease whose onset and advance in a broad age group is lifestyle-related, but the genetic background of individuals is also a very important factor. Nevertheless, the relationship between caries frequency and genetic background remains unclear, especially for genetic polymorphisms of salivary proteins. The salivary mucin MG2 plays a role in facilitating the clearance of bacteria, interacts with Streptococcus mutans, which may be a caries pathogen, and can function as an antimicrobial agent. Here, we evaluated the statistical relationship of genetic polymorphisms of tandem repeats in the gene encoding MG2 (MUC7) with the frequency of pediatric severe caries in the Japanese population. Genomic DNA from lingual mucosal cells of 70 healthy and 92 caries patients was purified, and the frequency of genetic polymorphisms in MUC7 was evaluated by PCR. The results indicated that alleles of 6 (the most common allele) and 5 tandem repeats were observed in control and caries groups. Differences in the frequencies of polymorphisms were analyzed by Fisher's exact test. P-values for the frequencies of polymorphisms in MUC7 were as follows: 5-5 versus 5-6 repeats, 0.743; 5-5 versus both 5-6 and 6-6 repeats, 1.00; 5-6 versus 6-6 repeats, 0.254; 5-6 versus both 5-5 and 6-6 repeats, 0.266; 6-6 versus 5-5 repeats, 1.00; 6-6 versus both 5-5 and 5-6 repeats, 0.341. Our data suggest no significant association between genetic polymorphisms in the MUC7 gene and caries susceptibility in the Japanese pediatric population. and salivary buffering capacity, may affect caries onset 4). In addition, some salivary proteins (a genetic host factor) that have antibacterial properties and mineralization effects may affect the caries process 5). Thus, various factors are involved in caries onset and development. Mucins (MG), which play multiple roles in the oral cavity, are salivary glycoproteins. Two distinct mucins, MG1 and MG2, are respectively synthesized from the MUC5B and MUC7 genes. These glycoproteins have been identified and characterized as preferentially expressed and secreted by submandibular, sublingual, and minor salivary glands 6-8). MG2, with a molecular weight of 150-180 kDa, is a

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.gens in dental plaque is necessary for estimating the risk of periodontal disease development in children.There have been various methods used for the detection of putative pathogens, including direct microscopy, enzyme tests, enzymelinked immunosorbent assays, DNA fingerprinting and southern blots 1,5,6) . Recently, several putative periodontal pathogens have been detected in a number of studies using polymerase chain reaction (PCR) 1,2,4,[7][8][9][10] . PCR is a powerful tool which can be utilized to address many of research topics. This assay using DNA primers is quick, relatively simple, and able to detect low numbers of bacterial species. 16S ribosomal DNA (rDNA), a small bacterial subunit, can be effectively used for the PCR primers, because it