A previous study showed that transcutaneous immunization with the 40-kDa outer membrane protein of Porphyromonas gingivalis (40k-OMP) elicits humoral immunity that protects from abscess induction by P. gingivalis. In this study, we assessed the potential of 40k-OMP as a transcutaneous vaccine against oral P. gingivalis infection. Transcutaneous immunization of mice with 40k-OMP alone or 40k-OMP plus cholera toxin (CT) elicited 40k-OMP-specific IgG and IgA antibody (Ab) responses in serum and IgG Abs in saliva. These Ab responses were maintained for at least 1 year after immunization, except for serum IgA Abs induced by 40k-OMP alone. Importantly, IgG Abs generated by transcutaneous immunization with 40k-OMP alone, or with 40k-OMP plus CT, inhibited hemagglutinating activity of P. gingivalis. Furthermore, mice transcutaneously immunized with 40k-OMP plus CT, but not 40k-OMP alone, showed significant reduction of alveolar bone loss caused by oral infection with P. gingivalis even 1 year after immunization. These results suggest that 40k-OMP is an effective transcutaneous vaccine against P. gingivalis infection and may be an important tool for the prevention of chronic periodontitis.

View full abstract

It is clinically important to check whether sufficient supporting bone mass is maintained in subjects with a low calcium diet. In this study, alveolar and femoral bone mass were measured after tooth movement in calcium-sufficient and -deficient rats, and the correlation between mechanical stress and bone mass was examined using the serum level and histological observation. Seventy rats were divided into 2 groups: normal (NDG) and low calcium diet (LCG) groups. After feeding for 28 days, the distance of tooth movement and the alveolar and femoral bone mass were observed on days 1, 3, 5 and 7 after fitting the appliance. Tooth movement distance was large in LCG. Alveolar bone mass in NDG and LCG showed a different tendency than tooth movement; the former was increased and the latter was decreased. Body weight decreased from the start of the experiment until day 3 in both groups, and increased gradually thereafter. Femoral bone mass in NDG slightly decreased and then recovered at day 7, but such a result was not observed in LCG. These results suggest that the tooth was able to move when an orthodontic force was applied in rats, even in cases of low alveolar bone mass, although various physical influences were present.

View full abstract

Oral submucous fibrosis (OSF) is a common premalignant condition of the mouth with areca nut chewing habit in the Asian subcontinent. It is characterized by restricted mouth opening, tongue protrusion and cheek flexibility. Though there are many histological studies of OSF reporting fibrosis and hyalinization in the sub-epithelium, there is a paucity of information related to the association of fibrosis and mouth opening (MO) and muscle changes in this condition. The present study was undertaken to study the association between mouth opening and fibrosis; and to study the degree of alterations involving muscle fibers as the disease progresses. However, the statistical analysis showed that there is no correlation between stage of mouth opening and grading of fibrosis as suggested by the insignificant ‘p’ value.

View full abstract

The purpose of this study was to compare gene expression profiles of peri-implantitis and periodontitis to elucidate potential differences at the molecular level. With the help of microarray analysis, genome-wide gene expression of inflamed peri-implant granulation tissue, inflamed and healthy periodontal tissues (n=48 patients) were compared and the data were validated by real-time reverse transcription polymerase chain reaction. After highlighting different gene classes, we focused on the extracellular matrix-receptor interaction pathway and gene expression of extracellular matrix molecules, their receptors and matrix degrading enzymes. Only genes of non-fibril-forming collagens (types IV, VI, VII, and Q) were increased in peri-implantitis compared to periodontitis, whereas the expressions of two fibril-forming collagens (types III and K) were decreased in peri-implantitis, which suggested that peri-implant tissue re-models faster than periodontal tissue in vivo. Furthermore, cathepsin D and cathepsin S seem to participate in the destruction of peri-implant connective tissue. Despite their clinical similarities, the present investigation demonstrated that peri-implantitis and periodontitis are two different disease entities at least at the messanger ribonucleic acid level. The data provide insight for future studies aimed at dissecting the pathogenesis of peri-implant inflammation.

View full abstract

This review shows the biochemical aspect of enamel formation focused on porcine amelogenesis.
Volumetric changes in the chemical components of secretory stage enamel intimate that enamel crystals thicken as amelogenin, the major protein component, decreases. Solubility behaviors and hydrophobicity analyses of amelogenin derivatives suggest the hypothesis that cylindrical amelogenin forms micelles. This model explains how amelogenin constructs a large structure, which forms a matrix, and continuously yields space as the crystals thicken. In porcine secretory enamel, mineral volume increases with depth, gaining space for thickening the existing crystallites by shrinking amelogenin micelles through the removal of C-terminal and 13-kDa peptides from the prototype 25-kDa amelogenin, the most abundant porcine amelogenin gene product, by the action of enamelysin (MMP-20) and enamel matrix serine proteinase (EMSP1), respectively.
During the secretory stage, the crystallites thicken in the deeper secretory enamel, although calcium ions are supplied by ameloblasts. Another morphological feature of the crystallites is that they are all nearly the same size within the same developmental stage. There are several enamel proteins and their cleavage products have calcium binding activity and binding affinity for crystallites. The 25-kDa amelogenin and 89-kDa enamelin, both neutral insoluble, are involved in slow crystallite growth by trapping calcium ions secreted by ameloblasts, and may control by inhibiting newly nucleated crystals between existing crystallites. The calcium binding proteins derived from the C-terminal side of sheathlin (ameloblastin/amelin) and 32-kDa enamelin, belonging to the neutral soluble fraction, act as a calcium carrier to transport calcium ions to deeper secretory stage enamel. Sheath protein derived from the N-terminal side of sheathlin is the main protein constituent of the enamel sheath.
Enamelin may be involved in initial crystal formation as it is immuno-histochemically shown to be localized on or around the initial nucleated crystals in a presecretory stage matrix. This is confirmed by no crystal formation in the enamel of enamelin knock-out mice. This conflicts with the inhibition of new nucleation between the existing crystallites in advanced secretory stage enamel. Enamelin may have multi-functions which are involved in the induction of nucleation in a particular phase of the molecule and inhibition in other phases, or change its function with the products produced during each degradation step.

View full abstract