[in Japanese]

View full abstract

The ultimate goal of periodontal treatment is the regeneration of periodontal tissues which have been lost due to periodontal disease. Recently, enamel matrix derivatives (EMD) have been introduced as an agent with the potential to enhance the regenerative process. However, there is limited knowledge of the biological mechanisms underlying the activity of EMD.
The purpose of the present study was to evaluate the EMD effects on regulation of alternative splicing of fibronectin (FN) mRNA in two regions (EDA, EDB) using human gingival fibroblasts (GFs)
GFs were grown to confluence and treated with EMD (0, 5, 25, 50, or 100μg/ml) for 24 h prior to mRNA or protein assessments. Semi-quantitative RT-PCR with ³²P-end labeled sense primers was used to determine the effects of EMD on total and splice variant mRNA levels. 32P-labeled products were excised from polyacrylamide gels following electrophoresis, and radioactivity measured using scintillation spectroscopy.
Immunocytochemistry with fluorescent labeling was used to evaluate the expression of FN and EDA⁺at the protein level under confocal laser scanning microscopy.
Our results showed that EMD treatment significantly increased the relativelevels of EDA⁺FmRNA over baseline levels (without EMD) in a dose-dependent manner (0, 5, 25, 50, 100μg/ml; p<0.01, ANOVA).
In contrast, the relative levels of EDB+mRNA and total FN mRNA level were unchanged with EMD treatment.
On the protein level, immunolocalization of FN and EDA⁺did not show any significant changes following EMD treatment relative to baseline levels.
In conclusion, EMD specifically increased EDA⁺mRNA levels in a concentration-dependent manner, with no apparent effects on the protein level.
These results suggest that EMD has functional activities similar to those previously reported for TGF-. A in the regulation of FN splicing. J. Jpn. Soc. Periodontol., 43: 107-117, 2001. Key words : enamel matrix derivative, fibronectin, splicing

View full abstract

We studied tooth displacement with vertical loading in early experimental periodontitis using the following analyses: (1) changes in periodontal parameters, (2) changes in tooth displacement, and (3) correlation between clinical parameters and tooth displacement. The mandibular left third premolar was the experimental tooth. Experimental periodontitis was induced with nylon floss ligature placed into the gingival sulcus. Six beagle dogs with good oral and general health were used. Vertical loading was initiated by placing a balance weight of 10 g to 100 g, maintained for 10 seconds. Tooth displacement with vertical loading was measured at baseline, 1, 3, and 6 days after induced experimental periodontitis. Periodontal parameters, such as probing pocket depth (PPD), probing attachment level (PAL), gingival crevicular fluid volume (Periotron®) and tooth mobility (Periotest®) were measured simultaneously. Results were as follows: (1) Although PPD, PAL, and Periotron® increased significantly on day 1, little changes was seen until day 3 and all clinical parameters significantly increased on day 6. (2) The distance of phase 1, defined as rapid elastic tooth intrusion, increased significantly on day 1, was maintained until day 3, and significantly increased again on day 6. (3) The distance of phase 1 was more correlated with PPD than other clinical parameters. These results suggested that tooth displacement synchronized with clinical changes. Measurement by a laser displacement transducer detected the delicated changes in tooth displacement in early experimental periodontitis. J. Jpn. Soc. Periodontol., 43 : 118-127, 2001.

View full abstract

The purpose of this study was to evaluate the use of cross-linked alginate gel forperiodontal tissue regeneration. Class II furcation was experimentally created in the mandibular premolars of beagle dogs. Periodontal regenerative treatments were then performed with and without topical application of crosslinked alginate gel. A histological evaluation of the effect on new tissue formation, was then performed by comparing periodontal fissure regeneration with and without topical application ofcross-linked alginate gel 2, 4, and 8 weeks after from the flap operations. The following results were obtained:
1. After two weeks, the underdeveloped tissue had enabled the epithelium to intrude into the furcation in the animals that did not receive a topical application of cross-linked alginategel. In the animals that received the application of cross-linked alginate gel, however, the furcation was fully regenerated by new tissue, preventing the epithelium from entering.
2. Throughout the experiment, almost twice as much regenerated cementum was observed in the animals that received the topical application of cross-linked alginate gel compared to those that did not. This difference was statistically significant (p <0. 01). Furthermore, the amount of new regenerated cementum in the second post-operative week was about twice that occurring in the fourth post-operative week. The formation of new cementum in the fourth and eighth post-operative weeks was not significantly different.
3. Regarding the regenerating of new bone, not much of an effect was noticed in either the control or the experimental animals after the second post-operative weeks, but results were observed thereafter. New bone was regenerated in both the cross-linked alginate gel on the regeneration of new bone was statistically significant (p <0. 01).
Consequently, the use of cross-linked alginate gel for the regeneration of periodontal tissue was judged to be beneficial. J. Jpn. Soc. Periodontol., 43: 128-140, 2001.

View full abstract

The purpose of this study is to evaluate the availability of a bioabsorbable collagen barrier-membrane for guided bone regeneration (GBR).
Subjects were 18 beagle dogs and materials were dome-shaped membranes. Prior to experiments, both first molars in the mandible were extracted. After 3 months of healing, mucoperiosteal flaps were reflected and experimental defects created in the alveolar bone. Theexperimental bone defect on one side was completely covered with the membrane (experimental group). On the contralateral side, the mucoperiosteal flap was repositioned without the membrane (controls).
After 6 and 12 weeks postoperation, bone formation was determined by computer-assisted digital subtraction image analysis and histologically.
The experimental group showd greater bone regeneration than controls under digital subtraction imaging. In controls, original bone crests were resorbed and bone formation at the bottom of the defect was slight. In the experimental group, slight resorption of original bone crests was observed and the defect was almost completely regenerated with new bone.
This snggests that hioahsorhahle collagen membrane is feasibly biocompatible and provides suitable space for bone regeneration. J. Jpn. Soc. Periodontol., 43: 141-154, 2001.

View full abstract

Sensory nociceptive neurons not only have afferent functions but also peptidergic efferent functions which help to regulate immune and inflammatory responses by releasing neuro-peptides. Diabetes mellitus (DM) is well known to have peripheral neuropathy and the risk factor for periodontitis. The purpose of this study was to investigate the nerve fiber distribution and regeneration by using gingivectomy model of the experimental diabetic rats (DM rath). Three, 7, 14 days after gingivectomy, tissue were observed for nerve growth factor receptor (NGFR) and calcitonin gene-related peptide (CGRP) immunoreactivity. DM rats showed the decreasing NGFR immuno-reactive fibers in junctional epithelium compare to control. Reinnervation was also delayed with wound healing delay. DM group showed week CGRP immunorreactivity compare to control group. In the control group, 7 days after surgery, a number of increasing NGFR positive sprouting nerves were shown to have regenerative periodontal connective tissue compare to other time. These results indicate that the dye-back had already occured in gingival tissue, and delaied the sprouting and regeneration of nerve fibers. This reason speculates to decline of NGF expression include the wound healing delay. J. Jpn. Soc. Periodontol., 43: 155-165, 2001.

View full abstract

A local drug delivery system for treatment of periodontal pockets by antibiotic is often used on patient with periodontitis. However, a well-known side effect of the long-term use of antibiotics is the increase in the number of resistant bacteria, such as MRSA, which is a serious medical problem.
Recently, natural pharmacological agents have been examined for their anti-microbial efficacy. For example, a polyphenol component in Japanese green tea and glycyrrhizin in a Glycyrrhizae Radix have been shown to inhibit HIV virus proliferation.
We already have been reported the clinical evaluation of some Chinese traditional drugs, such as Coptidis Rhizoma or Lonicerae Flos, and concluded that they have potential to be used as anti-inflammatory agents against periodontitis. In this present study, the traditional Chinese crude drugs from Folium Strobilanthis and Radix Strobilanthis were tested for their in vitro activity against periodontopathic bacteria.
Also, the latter drug was evaluated clinically for use in a mouth rinse.
The results suggest that Chinese traditional drugs Folium and Radix Strobilanthis inhibited the growth of periodontopathic bacteria and cariogenic bacteria in vitro. Furthermore, Radix Strobilanthis inhibited the proliferation of oral bacteria when used in a mouth rinse. J. Jpn. Soc. Periodontol., 43: 166-172, 2001.

View full abstract