Degradation of single bottle type self-etching primer effectuated by the primer's storage period

PURPOSE: To examine the hydrolytic stability of the functional methacrylate monomer utilized in single bottle type self-etching primers, by using the 13C nuclear magnetic resonance (NMR) technique in order to understand why the bond strength of resin to the dentin decreased, when the primer's storage duration was prolonged. METHODS: After deuterium oxide was added to the Mega Bond Primer (MB), or Unifil Bond Primer (UB), the MB or UB solutions were then stored at 37 degrees C for 0, 3, and 10 weeks, respectively. At the end of the storage periods, 13C NMR observations of the MB or UB solution were performed at 25 degrees C by using an EX-270 spectrometer. RESULTS: The acidic and/or hydrophilic methacrylate monomer utilized in single bottle type self-etching primers became altered during the primer's storage period. Alteration of the functional monomer was possible since the acidic monomer, utilized in the self-etching primer, could supply sufficient amounts of hydronium ions, which were the result of the dissociation of the acidic group in the acidic monomer. The degradation of the primer, caused by the alteration of the functional monomer, would result in the degradation of the etching and/or priming efficacy on the tooth. The bond strength, as a result, would become decreased as the storage period was prolonged.     

Changes in protein secretion by rat submandibular salivary glands after enlargement caused by repeated amputation of the lower incisor teeth.

The lower incisors of male rats were repeatedly amputated at 3- or 4-day intervals for about 1 month. Four days after the last amputation, submandibular saliva was collected from the anaesthetized rats by intra-oral cannulation, using methoxamine (6 mg/kg), an α-adrenomimetic drug, as an acute secretory stimulus. The rats showed enlarged submandibular and sublingual glands and the protein concentration was significantly less in submandibular saliva than in controls. The types of protein secreted by the rat submandibular gland in response to methoxamine normally differ from those secreted in response to isoprenaline. In the enlarged glands, methoxamine stimulation caused the secretion of proteins similar, by polyacrylamide gel electrophoresis, to those normally secreted in response to isoprenaline, suggesting that repeated lower incisor amputation had caused the glands to lose their normal responsiveness to α-adrenergic agonists. An abnormal protein was also secreted, identical electrophoretically and immunologically with one secreted by the enlarged submandibular glands of rats exposed to chronic isoprenaline administration.     

Coverage of gingival recession defects using guided tissue regeneration with and without adjunctive enamel matrix derivative in a dog model

The aim of this study was to clarify the adjunctive effect of enamel matrix derivative (EMD) on expanded polytetrafluoroethylene membrane guided tissue regeneration (GTR)-based root coverage by creating gingival recessions in beagle dogs. Recessions were treated with GTR + EMD, GTR alone, or neither GTR nor EMD (control). The control group was characterized by long junctional epithelium and little bone formation. The GTR + EMD group showed a statistically significant increase (P < .01) in new bone and cementum formation compared with the GTR group. The results of the present investigation suggest that the adjunctive use of EMD with GTR promotes formation of new bone and cementum without root resorption in recession-type defects in dogs.     

Effect of reacted acidic monomer with calcium on bonding performance

We determined the number of reacted and unreacted 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) molecules with calcium during the demineralization process of hydroxyapatite or dentin by 10-MDP-based one-step (Clearfil Tri-S Bond, TS) or two-step self-etch adhesive (Clearfil SE Bond Primer, SE). We then examined the effects of the number of reacted and/or unreacted 10-MDP molecules on the initial bond strength and bond durability of the resultant adhesive layer. The null hypotheses were that (1) the etching efficacy of tooth apatite by 10-MDP used in TS was the same as that in SE, and (2) the unreacted 10-MDP polymer included within the adhesive layer does not affect bond durability. Addition of hydroxyapatite or dentin to the TS and SE resulted in decreases in the NMR peak intensities for 10-MDP. The peak intensity for 10-MDP showed a greater reduction in SE than in TS, consistent with the observation that SE provided significantly higher initial mean bond strengths than TS. Further, the unreacted 10-MDP polymer within the adhesive layer did not decrease the mean bond strength, despite the application of 20,000x thermo-cycling.     

The trans-chromosomic mouse-derived human monoclonal antibody promotes phagocytosis of Porphyromonas gingivalis by neutrophils

BACKGROUND: As a safe immunotherapeutic approach, human monoclonal antibody (hMAb) may be effective in clearing periodontopathic bacteria. The trans-chromosomic (TC) technology has recently been applied to construction of the TC mouse, which enables us to incorporate entire human chromosome fragments containing immunoglobulin (Ig) gene cluster. The aim of this study is to establish TC mouse-derived hMAb, and to test the in vitro opsonophagocytic activity. METHODS: Human Ig-producing TC mouse was immunized by recombinant 40-kDa outer membrane protein (r40-kDa OMP) of Porphyromonas gingivalis 381, and the spleen cells were fused with the mouse myeloma cell line. The specificity of antir40- kDa OMP hMAb was evaluated with the enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance assays. Flow cytometric analyses were performed to assess the opsonophagocytic activity. RESULTS: We successfully constructed 99 IgG isotype clones (IgG1: 84; IgG2: 11; IgG4: four clones), which were specifically reactive with r40-kDa OMP. The anti-r40-kDa OMP IgG1 hMAbs promoted phagocytosis of P. gingivalis by neutrophils. Futhermore, an increased opsonophagocytic activitity of anti-r40-kDa OMP IgG1 hMAbs was observed not only in P. gingivalis 381, but also in the W50, W83, and Su63 strains. CONCLUSION: Our results document the TC mouse-derived hMAb to promote neutrophil phagocytosis of P. gingivalis, suggesting an immunotherapeutic option for clearance of P. gingivalis.     

Metastasis of adenoid cystic carcinoma of the mandible to the Gasserian ganglion.

A case of adenoid cystic carcinoma of the mandible in a 47-year-old woman metastasized to the Gasserian ganglion probably through the perineural space of the inferior alveolar nerve. The patient was treated by irradiation after excision of the tumor from the ganglion. She is currently an outpatient in the oral and maxillofacial surgery department; two years and seven months after the first examination, there is no sign of recurrence or metastasis of adenoid cystic carcinoma.