Unique functions of hydroxyapatite with mutans streptococci adherence.
OBJECTIVE
Hydroxyapatite (HA) is used as a construction material for artificial supplementation of enamel tooth surfaces to improve oral hygiene. This study examined in vitro HA interactions with mutans streptococci (MS) and bacterial adherence to small (nanosize) crystal form of HA beads having a protean hexagonal structure. The adsorption and physical effects of HA employed in vivo is also described.


METHODS
[3H-thymidine]-labeled streptococci were incubated with HA noncoated or coated with salivary components or salivary agglutinin peptide (SRCRP2), a receptor for streptococcal surface proteins. Bacterial adhesion activities on HA were measured by uptake of [3H-thymidine]. Application of HA paste in an individual tray was tried on the tooth surface, and its effects on the colony ratio of MS/total streptococci (TS) in saliva were analyzed by culture technique.


RESULTS
The adhesion assay showed that the binding of streptococci to HA was inhibited by coating with salivary components, whereas coating with SRCRP2 had nearly no influence on binding with or without Ca+. Further, treatment with HA decreased the adherence of Streptococci mutans to roughened enamel surfaces by one-third. In vivo application of a HA dentifrice to individual teeth demonstrated that the colony number ratio of MS/TS slowly decreased.


CONCLUSIONS
MS adhesion to HA was restricted by both salivary components, except for SRCRP2, and the physical effects of HA; in addition, the material itself has a unique effect for removing MS from the oral cavity.
Arakawa
Tadayoshi
T
Central Research and Development, Sangi, Tokyo, Japan.
Fujimaru
Takeshi
T
Ishizak
Tsutomu
T
Takeuchi
Hiroaki
H
Kageyama
Masato
M
Ikemi
Takuji
T
Hanada
Nobuhiro
N
Watanabe
Haruo
H
Senpuku
Hidenobu
H
D018829:Adhesins, Bacterial / Q000737:chemistry / Q000378:metabolism*; D000328:Adult; D000595:Amino Acid Sequence; D000704:Analysis of Variance; D001422:Bacterial Adhesion; D003743:Dental Enamel / Q000382:microbiology; D003802:Dentifrices / Q000737:chemistry / Q000494:pharmacology*; D017886:Durapatite / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D053758:Nanoparticles; D011485:Protein Binding; D012463:Saliva / Q000382:microbiology; D012471:Salivary Proteins and Peptides / Q000378:metabolism*; D013295:Streptococcus mutans / Q000187:drug effects* / Q000502:physiology*; D013499:Surface Properties
D018829:Adhesins, Bacterial; D003802:Dentifrices; D012471:Salivary Proteins and Peptides; C068465:salivary agglutinin receptor, Streptocococcus; D017886:Durapatite