Marginal adaptation of four flowable composites was evaluated by measuring wall-to-wall contraction gap in a cylindrical dentin cavity. Four combinations of conventional and flowable resin composites were employed. The cylindrical dentin cavities prepared in extracted human molars were restored with one of these composites after pretreatment according to the manufacturers' instructions. For the positive control, the cavity was conditioned with EDTA, primed with 35% glyceryl mono-methacrylate (GM), and Clearfil Photo Bond was applied prior to the composite filling. Ten specimens for each material, 160 in total, were examined. In the positive control groups, marginal adaptation was completed with the exception of the Unifil-S specimen. With the commercial bonding systems, gaps were observed in two some specimens out of 10. Four flowable resin composites exhibited comparable marginal adaptation compared to the conventional high-viscous composite though complete marginal integrity could not be obtained when the cavity was pretreated with the commercial dentin bonding systems. It was concluded that the flowable resin composite would be clinically useful in combination with a highly effective experimental dentin bonding system composed of EDTA, GM and Clearfil Photo Bond.

View full abstract

Some properties of experimental binders, which were mixed by different NH₄H₂PO₄/MgO ratio (Mg70-P30, Mg60-P40, Mg50-P50, Mg40-P60, Mg30-P70) for dental phosphate-bounded investment were evaluatd. The increases of MgO made compressive strength higher both before and after firing. All binders expanded when setting, then the decrease of MgO was effective to expand. Furthermore, all binders must be contracted with heating, but they were slightly converted to expansion over 700°C. There were found same components among binders tested on the XRD chart. However, these sensitivities were definitely different. According to SEM images on the set surfaces, large crystalline-like compounds were observed from Mg30-P70 and Mg40-P60, but fiber-like compounds were observed from Mg70-P30 and Mg60-P40. These results suggested that the increase of MgO was helpful for strength and reactive acceleration, but undesirable for sufficient reaction at set because of small setting expansion.

View full abstract

Osteoprotegerin (OPG) is an osteoblast-derived secreted member of the TNF receptor superfamily that inhibits osteoclastogenesis. We examined the effects of OPG administration on the distribution, ultrastructure and vacuolar-type H⁺-ATPase expression of osteoclasts and resulting trabecular bone loss in the femurs of ovariectomized (OVX) mice. Two-month-old female ddY mice were allocated to the following groups : (1) untreated sham-operated controls, (2) untreated OVX, and (3) OPG-administered OVX mice. Postoperatively, OPG (0.3 mg/kg/day) was intraperitoneally administered daily to OVX mice for 7 days. The results revealed that trabecular bone area/unit medullary area in untreated OVX mice was significantly lower than that of sham-operated control mice. OPG administration to OVX mice significantly increased trabecular bone area, which was similar to that of sham-operated control mice. The number of TRAP-positive osteoclasts along the trabecular bone surfaces in OPG administered OVX mice was not significantly decreased, but OPG administration caused disappearance of ruffled borders and decreased of H⁺-ATPase expression in osteoclasts. Our results suggest that low-dose OPG administration significantly reduces trabecular bone loss in OVX mice via impairment of the structure and bone resorbing activity of osteoclasts.

View full abstract

Bisphenol A is one of a endocrine disruptor substances. It was considered that it has an estrogenic reactivity and effects on the generation, immunity and nerve systems. Light-cured restorative dental material was made from bisphenol A. It was already reported that a small amount of bisphenol A eluted from light-cured restorative dental materials. In this study, we developed sensitive chemiluminescent enzyme immunoassay (CL-EIA) which is not requirement of complicated pretreatment. Three kinds of bis-GMA-based resins, two kinds of UDMA-based resins and a kind of Bis-MEPP-based sealant were evaluated. The materials were irradiated with a visible light source and incubated into phosphate buffered saline (PBS) for 24h. The supernatant was determined by the CL-EIA. The concentration of BPA-like immunoliactivity substances in eluted from the six materials after 24h were determined by the CL-EIA, and the results were as follows : 1415.3 pg, 809.5 pg and 1728.1 pg/mg resin for Bis-GMA-based resin, 15.6 pg and 108.2 pg/mg resin for UDMA-based resin and 1488.3 pg/mg resin for Bis-MEPP-based resin, respectively.

View full abstract

From the retrospective consideration of diagnosis and treatment procedures in intractable cases in Cleft Lip and Palate patient, which required long treatment period, the cause of lengthening were discussed.
1. Difficulty of maxillary expansion.
2. Effects on bone grafting at cleft site by expansion.
3. Clinical effectiveness of Maxillary Protractor Appliance (MPA) and Chin cap therapy.
4. Difficulty of orthodontic movement on pre-maxilla in Bi-lateral Cleft Lip and Palate patient.
5. Unpredictable results of orthognathic surgery and its orthodontic countermeasures.
To improve these problems, re-evaluation of our present surgical methods and procedure of orthodontic expansion were recommended. Importation of new analyzing technique and requirements in treatment system were also reported.

View full abstract

An extraction of the upper central incisor of young patients is extremely rare because missing central incisors creates an esthetic and functional problem with specific orthodontic and prosthetic considerations. This article describes a case requiring a combination of orthodontic and prosthodontic treatment in a young patient with Class II Division 1 malocclusion and previously traumatized upper central insisors. In this case, the upper central incisors with root resorption and the lower second premolars were extracted, and then fixed appliances were placed in upper and lower arches to align the teeth in order to close the spaces and to reduce the overjet. Orthodontic mesialization of both lateral incisors toward the midline was followed by prosthodontic modification with the porcelain laminate veneer (PLV) method. The PLVs were placed on both lateral incisors to simulate the appearance of both central incisors to compensate for the limitations of orthodontic treatment and to harmonize the tooth size. Four years of follow-up revealed that treatment had successfully restored esthetics as well as function.

View full abstract