Novel Herbal Therapeutic YH23537 Improves Clinical Parameters in Ligature-Induced Periodontal Disease Model in Beagle Dogs

Currently, available medicine does not satisfy the clinical unmet needs of periodontal disease. Therefore, novel drugs with improved efficacy profiles are needed. We previously demonstrated that YH14642, water extracts of Notoginseng Radix and Rehmanniae Radix Preparata, improved probing depths in double-blind phase II clinical trial. However, it still has hurdles for commercialization due to the low efficiency of active compound extraction. To resolve this issue, we developed YH23537 through process optimization to extract active compounds efficiently while still achieving the chemical profile of YH14642. In this study, we investigated the therapeutic effects of YH23537 compared with YH14642 using a canine model of ligature-induced periodontitis. Human gingival fibroblast (hGF) cells were treated with various concentrations of YH23537 or YH14642 with lipopolysaccharide (LPS) for 24 hr. IL-6 and IL-8 levels in the conditioned media were determined using Luminex. Sixteen 3-year-old male beagle dogs had their teeth scaled and polished using a piezo-type ultrasonic scaler under general anesthesia and brushed once daily for the following 2 weeks. Two weeks after the scaling procedure, the left upper second premolar (PM2), third premolar (PM3), and fourth premolar (PM4) as well as the left lower PM3, PM4, and first molar (M1) were ligated with silk-wire twisted ligatures. The dogs were fed with soft moistened food to induce periodontitis for 8 weeks, and the ligatures were then removed. YH23537 and YH14642 were administered for 4 weeks, and clinical periodontal parameters such as plaque index (PI), gingival index (GI), probing depth (PD), clinical attachment level (CAL), and bleeding on probing (BoP) were determined before and 1, 2, 3, and 4 weeks after treatment. YH23537 inhibited IL-6 and IL-8 secretion in a dose-dependent manner in hGF cells stimulated with LPS. The IC₅₀ values for YH23537 were 43 and 54 μg/ml for IL-6 and IL-8, respectively, while the values for YH14642 were 104 and 117 μg/ml, respectively. In the animal study, clinical parameters including GI, PD, CAL, and BoP were significantly increased after 8 weeks of ligature-induced periodontitis. The YH23537 300 and YH23537 900 mg groups had significant improvements in CAL from 1 to 4 weeks after treatment in comparison to the placebo group. GR values in the YH23537 900 mg group were decreased throughout the treatment period. GI values were also reduced significantly after 4-week treatment with 300 and 900 mg of YH23537. YH23537 at 300 mg doses showed comparable efficacy for CAL and GR with 1,000 mg of YH14642. YH23537 showed therapeutic efficacy against periodontitis in dogs, mediated by anti-inflammatory effects. These findings indicate that YH23537 has the potential for further development as a new drug for patients suffering from periodontal disease.

Corrosion by galvanic coupling between carbon fiber posts and different alloys

OBJECTIVES

The corrosion of metal type (NiCr, copper, etc.) posts in post and core restorations has been a well known fact over the last few years. A new generation of carbon fiber posts is now playing an extensive role in dental prosthetics, but these posts may, in some cases come in contact with alloys used for restoration purposes. The objective of this paper is to study the electrochemical behaviour of these posts in an artificial SAGF medium (Artificial Saliva Gal Fovet) for comparison with that observed for different alloys (gold, NiCr and amalgams) in the same medium, and to assess the coupling that might occur between these posts and alloys.

METHODS

Posts of different diameters (1-2.1 mm) were molded in resin, thus forming 10 x 3 mm pads that were mounted on a rotating electrode. Pads of identical dimensions were also made for each alloy. Voltammograms (current-tension curves) were plotted for every material in the SAGF medium at 25 degrees C with normal aeration and low aeration (bubbling purified argon) using a potentiometer with three electrodes to determine the position of the zero current potentials. Evans graphs were then plotted once the anode part of the alloy curves and the cathode part of the post curves had been processed with computer software. The potentials and the maximum coupling current densities were estimated.

RESULTS

Posts may be involved in galvanic coupling in the presence of oxygen. Galvanic activity in an aerated solution is highly probable upon contact with amalgams, but may also occur if the material in contact is NiCr alloy. Coupling between precious alloys and posts is improbable and can only induce very low currents in the presence of oxygen.

SIGNIFICANCE

This study devoted to coupling of carbon fiber posts and metals in the mouth, attracts attention to the fact that a corrosion reaction can be set-up in the infiltration conditions relevant to the prosthetic restoration.

In vitro fluoride release from restorative materials in water versus artificial saliva medium (SAGF)

OBJECTIVES

An extensive number of investigations have focused in recent years on the process of fluoride release by glass-ionomer cements. In order to compare the fluoride release of two recent resin-modified glass-ionomer cements (RMGICs) and one compomer, we investigated the initial and subsequent fluoride release in distilled water and in a mineral medium with composition similar to saliva (SAGF), as well as the renewal effect of the media on the release.

METHOD

A preliminary thermodynamic study defined conditions under which the measurements by fluoride-selective electrode potentiometry were not affected by the presence of Ca2+ ions in SAGF. Disk-shaped samples (5 mm x 3 mm) for each material were placed in 5 ml of distilled water (n = 12) or 5 ml of SAGF (n = 12) and fluoride released was measured after 1, 2 and 7 days. For the investigation of medium renewal effect, RMGIC sample were dipped into distilled water for 5 days. Subsequently 12 samples of each material were placed for 7 days into water or SAGF, with or without daily renewal of the medium before fluoride-release measurements. The elements present on the surface of the RMGICs were analyzed by scanning electron microscopy.

RESULTS

RMGICs released significantly more fluoride in water than in artificial saliva. The presence of CaF2 at the interface accounts for this phenomenon. The thickness of the CaF2 layer depends on the speed of its initial formation and renewal of the testing medium. A pattern of CaF2 formation was proposed.