Cytotoxicity of dental resin monomers in the presence of S9 mix enzymes

The purpose of the this study was to evaluate the cytotoxicity of dental resin monomers in the presence of a rat liver S9 mix containing cytochrome P 450 enzymes. JTC-12 cells derived from a monkey kidney were seeded on a 96-well multi-well-plate at 9 x 10(3) cells per well. After cultivation, the S9 mix was added to the wells as an S9 mix group (+S9), and PBS- was added to the other wells as a none-S9 mix group (-S9), then 7 different concentrations of various monomers were added to each well. All the specimens were cultured for another 24 hrs. The cell survival ratios (CSR) were calculated by using a neutral red cytotoxicity assay. CSR for 50 micrograms/mL of Bis-GMA/S9 mix was 92.6% while for none-S9 mix it was 6.6%. The values of CSR for UDMA, Bis-MPEPP, EGDMA, TEGDMA, DMAEM, 4-META and HEMA exhibited a reduction in cytotoxicity in the presence of the S9 mix. There were significant differences between +S9 and -S9 for respective monomers (p < 0.05). However, there were no significant differences between +S9 and -S9 for MMA (p < 0.05).     

Repair of periodontal angular bony defects evaluated by one- and two-dimensional radiographic analysis

The healing of eighteen angular periodontal bony defects was evaluated radiographically 1 year after treatment. The pretreatment and posttreatment radiographs were exposed and processed in such a way that identical images were obtained. There was no correlation between one- and two-dimensional expressions of healing in such defects, and relative area changes were consistently larger than relative linear changes of the same defects. The area gain of bone was strongly correlated to the following morphologic variables: length of bone surface, original defect area, and height of the defect.     

Esthetic replacement of a maxillary central incisor with an ITI 15-degree angled implant: a case report

Single-stage implants are frequently used, but their use in the anterior dentition has not been widely published. The purpose of this case report is to present the esthetic result of a single-stage implant to replace a maxillary central incisor, and to demonstrate the unconventional use of a 15-degree angled ITI implant. A 15-degree 12-mm hollow cylinder was placed with the angle reversed facially. The emergence profile of the adjacent roots was matched with the transmucosal portion, turning at the osseous crest. The implant was restored after 6 months with an ITI gold coping and transverse screw-retained crown. The gingival margin and the papillae were shaped by the transmucosal portion and the restoration. To date, the implant has been loaded for 24 months with an ideal soft tissue esthetic and radiographic appearance.     

Effect of presilanization filler decontamination on aesthetics and degradation resistance of resin composites

Filler-matrix coupling determines, to a large extent, the mechanical strength and clinical longevity of dental composites. The aim of this study was to examine how far a methodology to decontaminate filler prior to silanization may improve aesthetic performance in addition to physico-mechanical properties such as degradation resistance. It was reported that filler particles are surrounded and wrapped by a film that consists of multiple layers of silane molecules. X-ray photoelectron spectroscopy, however, revealed that silanization of filler particles largely depended upon siloxane bridge (Si-O-Si) formation between the silica surface and the silane molecule rather than on intermolecular bonding between adjacent silane molecules. In this study, we showed that filler decontamination resulted in a higher translucency, thereby providing a better aesthetic potential. In addition, experimental composites produced following presilanization decontamination of filler revealed a higher Vickers hardness value and a diametral tensile strength that was resistant to degradation by thermo-cycling.     

Effects of TGF-beta on hyaluronan anabolism in fibroblasts derived from the synovial membrane of the rabbit temporomandibular joint

Hyaluronan (HA) synthesis in the synovial membrane is affected by various chemical mediators. It is hypothesized that transforming growth factor-beta 1 (TGF-beta 1) would be a mediator to modulate HA synthesis in cultured synovial membrane fibroblasts of the temporomandibular joint (TMJ). Fibroblasts were extracted from the TMJ synovial membrane of four-week-old Japanese white rabbits. The amount of HA and expression levels of HA synthase (HAS) mRNAs induced by TGF-beta 1 treatment were analyzed by means of high-performance liquid chromatography and real-time polymerase chain-reaction, respectively. Both medium and large amounts of HA were enhanced by the stimulation of TGF-beta 1. HAS2 mRNA expression was enhanced 13-fold after six-hour stimulation with TGF-beta 1 (10 ng/mL), whereas HAS3 mRNA expression was not changed significantly. These results suggest that TGF-beta 1 enhances the expression of HAS2 mRNA in the TMJ synovial membrane fibroblasts and may contribute to the production of high-molecular-weight HA in the joint fluid.     

Characterization of mineral-binding 40-kDa glycoprotein extracted from young adult rabbit alveolar bone.

A forty-kilodalton (40-kDa) protein was extracted from alveolar bone of young adult rabbit with 0.5 M EDTA after extraction with 4 M GuHCl, and purified by gel-filtration, anion-exchange and hydroxyapatite columns using a high-pressure liquid chromatography system under denaturing conditions. The purified 40-kDa protein was not susceptible to bacterial collagenase and thrombin, but was cleaved by cyanogen bromide. The protein was stained blue with Stains-all. Among various lectins, concanavalin A and lentil lectin agglutinin bound to this protein, but peanut agglutinin, Ricinus communis agglutinin, phytohemagglutinin-E and wheatgerm lectin agglutinin did not. Lectin binding assays showed that the protein is a glycoprotein containing large amounts of mannose and/or glucose residues, but is not a fragment of proteoglycan. The amino acid composition of the protein shows a characteristically high content of acidic amino acids. Therefore, the mineral-binding 40-kDa glycoprotein is considered to be osteonectin/secreted protein acidic and rich in cysteine (SPARC), in terms of similarities to bovine and porcine osteonectins with regard to molecular weight and contents of glycoses and amino acids.     

Prevalence of Porphyromonas gingivalis in relation to periodontal status assessed by real‐time PCR

Many studies have examined the presence of Porphyromonas gingivalis in periodontal pockets. However, monitoring the number of bacterial cells is difficult. In this study, we performed quantitative analyses of P. gingivalis to clarify the relationship between the numbers of this organism and periodontal status. Using the TaqMan real‐time PCR system, we found a significant positive correlation (P < 0.0001) between the number of P. gingivalis and pocket depth. The slope of the regression line indicated that for every 1‐mm increase in pocket depth, the number of P. gingivalis increased 10‐ fold. There was also a significant reduction (P < 0.01) in the numbers of P. gingivalis before and after treatment. These results suggest that the absolute and relative numbers of P. gingivalis are closely associated with periodontal status, and that quantitative analysis of this organism is important for the evaluation of periodontal therapy.     

Clinical and histological evaluation of immediate-loaded posterior implants in nonhuman primates

PURPOSE: To evaluate a square-thread design implant and compare the bone-implant contact percentage between immediate-loaded and nonloaded implants (controls) in nonhuman primates. MATERIALS: Five nonhuman primates each received 3 implants, with a total of 5 control implants and 10 immediate-loaded implants in posterior regions of the mouth. Ninety days after surgery (and function was appropriate), block sections of the implants were removed and sectioned in 200-mum thick pieces. The block sections were stained with modified Masson for evaluation of the bone-implant contact percentage. RESULTS: One of the immediate-loaded implants failed. The bone-implant contact percentage of control implants ranged from 50.34% to 64.13% and averaged 56.3%. The bone-implant contact percentage of immediate-loaded implants ranged from 43.23% to 75.72%, with an average of 62.4%. Two implants had lower bone-implant contact percentage than the others, and when these are not included in the evaluation, the bone-implant contact percentage average increased to 67.6%. CONCLUSIONS: Immediate-loaded implants in the nonhuman primates often have a higher bone-implant contact percentage at 90 days than unloaded implants. The bone remodeling is different for loaded implant-bone interfaces than for unloaded conditions. However, 1 immediate-loaded implant failed, and 2 implants had lower bone-implant contact percentage than controls. Therefore, although there are benefits of immediate loading, there appear to also be some risks.