Periodontal evaluation of crown-root fractured teeth following modified crown lengthening surgery.

Objectives To evaluate long-term outcomes of modified crown lengthening procedures for crown-root fractured teeth, and to analyse factors that affect the periodontal health of the treated teeth.Methods The present study retrospectively analysed data from 22 patients (13 males and 9 females) who had presented with crown-root fractured teeth and received modified crown lengthening procedures combined with crown restoration for ≥13 months. In total, 26 crown-root fractured teeth were treated and examined for plaque index, probing depth, bleeding index, bleeding on probing, mobility and the crown margin location. The contralateral tooth and ipsilateral teeth mesial and distal to the treated tooth were used as controls. Data were assessed descriptively or analysed statistically with Mann-Whitney-U test at α=0.05.Results Recorded periodontal indices revealed stable periodontal status in 25 of 26 treated teeth with the mean values for aesthetic and functional VAS scores at 9.5. A negative correlation was observed between the subgingival crown margin location and the bleeding index.Conclusions The modified crown lengthening procedure is a feasible and minimally invasive therapeutic option for management of crown-root fractured cases.

Titanates deliver metal ions to human monocytes.

Amorphous peroxotitantes (APT) are insoluble titanium-based particles that bind a variety of metal compounds with high affinity; these particles could be sequestered locally in a solid phase to deliver metal-based drugs. Previous studies have confirmed the 'biodelivery' of metals from metal-APT complexes to fibroblasts, but not monocytes. Our goal in the current study was to use monocytic cytokine secretion to assess delivery of gold or platinum-based compounds from APT to human THP1 monocytes. Cytokine secretion was not triggered by APT alone or metal-APT complexes. In monocytes activated by lipopolysaccharide (LPS), APT alone enhanced or suppressed IL1beta or IL6 secretion, yet TNFalpha secretion was unaffected. Complexes of APT and Au(III) or cis-platin altered LPS-activated IL6 or IL1beta secretion most, TNFalpha least. Our results suggest that the APT deliver metals to monocytes.

The effects of repeated heat-pressing on properties of pressable glass-ceramics.

The aim of this study was to evaluate the properties of four heat-pressed glass-ceramic materials after repeated heat-pressing. Two commercially available heat-pressed glass-ceramic systems [Optimal pressable glass-ceramics (OPC and 3G) and Empress pressable glass-ceramics (Empress and Empress2)] were selected. Disc samples (14 mm x 1.4 mm) of each tested material were heat-pressed and used as controls. Sprue and button parts of the pressed groups were retrieved and used for repeated heat-pressing to construct specimens of re-pressed group. All the heat-pressed casting procedures were performed according to the manufacturers' instructions. A biaxial flexural strength (BFS) test (ISO 6872) was performed to determine the strength of pressed and re-pressed glass-ceramic disc specimens (n = 10) at a crosshead speed of 0.5 mm min(-1). Ions eluted from etching procedure were collected and examined using inductively coupled plasma mass spectrometer. Surface characteristics were examined with electron probe microanalysis, X-ray diffraction and secondary electron imaging (SEI). The data were analysed statistically (ANOVA + Tukey's HSD post hoc test, P < 0.05). The BFS values obtained ranged from 123.5 +/- 18.5 to 365.9 +/- 35.5 MPa. The re-pressed Empress2 group had a statistically significant higher BFS mean than the pressed control group (P < 0.05). The SEI micrographs of the lithium disilicate-reinforced glass-ceramic material (Empress2) showed a densely packed, interlocking microstructure and an increase in size with preferred orientation of the lithium disilicate crystals after repeated heat-pressing. Repeated heat-pressing treatment produced a statistically significant increase in the flexural strength of Empress2 glass-ceramic material.

Effect of pre-processing surface treatments of acrylic teeth on bonding to the denture base.

The aim of this study was to examine the bond strength between acrylic teeth after various surface treatments and processing with either a heat- or microwave-polymerized denture base material. Specimens were prepared and tested according to the methods described in American National Standard/American Dental Association Specification No.15 (Synthetic Polymer Teeth) using a special assembly. Three brands of acrylic teeth were used with the following treatments: control (no treatment), grinding and grinding plus sandblasting. Treatment groups were further divided into two denture base processing subgroups: heat-polymerized and microwave-polymerized methods. Denture base processing to the acrylic teeth was performed according to the manufacturer's recommendations. Bond strength test was performed using a universal testing machine with five specimens and each specimen is composed of six anterior teeth per experimental group. Data were analysed using a three-way anova and the Scheffe'F-test post hoc pair wise comparison at the 95% significance level. The mean bond strength values ranged from 33.1 +/- 4.1 to 51.6 +/- 2.5 MPa. The bond strength values of sandblasted surfaces were significantly higher than those of the ground surface and the control (P < 0.05). Combined (acrylic tooth and denture base resin) cohesive failures were disclosed in all tested samples. Acrylic tooth surface pre-processed surface treatment with grinding plus sandblasting and processed with a heat-polymerized denture base provided the greatest bond strength between acrylic tooth and denture base.

Induction of male sterile cabbage using a tapetum-specific promoter from Brassica campestris L. ssp. pekinensis.

The anther (tapetum)-specific gene BcA9 was isolated from Chinese cabbage, Brassica campestris L. ssp. pekinensis cv. Jangwon, using the Arabidopsis tapetum-specific A9 gene as a probe. The DNA and amino acid sequences of the coding region of the BcA9 gene showed high homology with A9 genes from Arabidopsis and B. napus. However, the DNA sequences of the 5' noncoding (promoter) region were different, except for the sequence from -281 to -89. To test the specific activity of this promoter, a plant expression vector, pGR011, was constructed by fusing the BcA9 promoter and the cytotoxic diphtheria toxin A-chain (DTx-A) gene. Several transgenic plants from cabbage, B. oleracea ssp. capitata, were obtained by way of Agrobacterium-mediated transformation. Southern blot analysis indicated that the tapetum-specific BcA9 promoter and DTx-A gene were successfully integrated into the genome of the transgenic cabbage. Under the control of the BcA9 promoter, expression of the cytotoxic DTx-A gene in the tapetal cells of the transgenic plants resulted in male sterile cabbages. Microscopic examination revealed that pollen grains in anthers of the male sterile cabbages had not developed normally, but the vegetative growth and phenotype showed no difference compared to wild-type plants.

On the Complexation of Cd(II) Ions with Polyacrylic Acid

Complexation of Cd(II) ions with polyacrylic acid has been studied potentiometrically and by 113Cd NMR spectroscopy. A Donnan model proposed by Marinsky (Marinsky, J. A., in "Ion Exchange and Solvent Extraction" (J. A. Marinsky and Y. Marcus, Eds.), Vol. 11, p. 237. Dekker, New York, 1993; Miyajima, T., in "Ion Exchange and Solvent Extraction" (J. A. Marinsky and Y. Marcus, Eds.), Vol. 12, p. 275. Dekker, New York, 1995) has been applied in order to correct for the electrostatic effect on the equilibria inherent in the polyelectrolyte nature of the polyions. The potentiometric studies showed that the bidentate ligand complex, (CdA2)0, is the dominant species, but the formation of monodentate ligand complex, (CdA)+, cannot be neglected at low degree of dissociation of the polyacid. The stability constants of the (CdA)+ and (CdA2)0 complexes have been determined to be approximately 3.2 x 10 and 1.6 x 10(2), respectively. These values are in good agreement with the stability constants of 4.1 x 10 and 1.0 x 10(2) for Cd(acetate) and Cd(glutarate) complexes, where acetate and glutarate ions are the monomer analog ligands of polyacrylic acid. The 113Cd NMR chemical shift change upon dissociation of the polyacid also indicates that the dominant complex is (CdA2)0, but (CdA)+ becomes more appreciable with the decreasing degree of dissociation of the polyacid.