Influence of firing times and temperature on color stability of low-fusing porcelains for high-functional gold alloys

The purpose of this study was to investigate the effect of firing conditions on color stability. Three commercially available porcelains for high functional gold alloys, Carrara (CA), Deguceram Gold (DE) and Duceragold (DU) were used. In this study color stability was investigated under fire treatment of 1st, 3rd, 5th times and firing temperatures of 0, 20, and 40 degrees C higher than the manufactures standard temperature (CA: 845 degrees C, DE: 780 degrees C, DU: 780 degrees C). L* was degreased in CA 5 times, DE 3 times, DU by repeated firing. No difference was observed among L* of firing temperatures DE and DU, but L* was degreased in CA with firing temperatures of 40 degrees C higher. a* was degreased in CA, DU, DE with repeated firing, a* was degreased 5 times at firing temperatures of higher. b* was degreased in DU, but b* was increased in CA and DE with 5 firings. b* was increased with 5 findings at firing temperatures of 40 degrees C higher.     

Effect of oxygen inhibition of self-etching adhesives on enamel-dentin polymer bond

PURPOSE: To determine effects of light curing of self-etching adhesives under ambient air or nitrogen on inhibition depths, enamel and dentin bond strengths, and marginal adaptation in dentin cavities. MATERIALS AND METHODS: The adhesives investigated were: AQ Bond (AQB, Sun Medical; Kyoto, Japan), iBond (IBO, Heraeus Kulzer; Hanau, Germany), One-Up Bond F II (OUB, Tokuyama; Tokyo, Japan), and Prompt L-Pop (PLP, 3M/ESPE; Seefeld, Germany). Inhibition layer thickness (ILT) was microscopically measured on 3 disk-shaped specimens each. Shear bond strengths (SBS) on enamel and dentin (n = 8) were determined after 10 min and 24 h water storage of bonded composite specimens (Venus, Heraeus Kulzer). The marginal adaptation of bonded Venus restorations in cylindrical dentin cavities was microscopically evaluated after 10 min of specimen storage (n = 8) in water. The data were statistically analyzed using parametric and nonparametric ANOVA and post-hoc tests at p < 0.05. RESULTS: Adhesive curing under air revealed significant ILT (microm) differences: IBO (4) < AQB (8) < PLP (12) < OUB (23). Upon curing in nitrogen atmosphere, no inhibition occurred with AQB, IBO, and PLP, and < 3 microm for OUB. SBSs on enamel after 10 min or 24 h did not differ according to curing atmospheres (p > 0.05). On dentin, SBSs were higher after curing under N2 (p < 0.05). Irrespective of the curing atmosphere, marginal adaptation was good for AQB and IBO and poor for PLP; OUB revealed significantly smaller gaps under N2 than under air curing. CONCLUSION: Oxygen inhibition of the four self-etching adhesives investigated had no or only moderate effects on bonding efficacy to enamel and dentin.     

Interleukin-6 receptor gene polymorphisms and periodontitis in a non-smoking Japanese population

AIM: The indispensable role of interleukin-6 receptor (IL-6R) in regulating IL-6 responses has been clearly established. We have previously reported that IL6R polymorphisms strongly influenced the serum levels of soluble IL-6R. In this study, we investigated the association between these genetic variations and periodontitis. MATERIAL AND METHODS: Among the seven novel IL6R single-nucleotide polymorphisms (SNPs) reported, we genotyped two important sites: the +48892 A/C in exon 9 and the -183 G/A in the promoter region. The SNP in exon 9 results in Asp-->Ala substitution in the proteolytic cleavage site of IL-6Ralpha. In total, 212 periodontitis cases and 210 healthy controls were genotyped using polymerase chain reaction, restriction fragment length polymorphisms and direct sequencing methods. RESULTS: Analysis of the genotype distribution of the +48892 A/C SNP in periodontitis patients and in controls revealed a suggestive association with aggressive (p = 0.04) and chronic periodontitis (p = 0.04). In addition, the carriage rate for the A allele was significantly higher in chronic periodontitis patients [p = 0.02, odds ratio (OR) = 2.25]. No association was found in the -183 G/A SNP. The two markers were in linkage disequilibrium (LD) (|D'| = 0.53). CONCLUSION: The IL6R+48892 A/C polymorphism could act as a risk factor for periodontitis; however, further association and biological studies are needed.     

A radiographical classification of Stafne's bone cavity

So-called Stafne's bone cavity of the mandible were detected by panoramic radiography in 24 patients seen at the Second Department of Oral and Maxillofacial Surgery, Meikai University Hospital, and five associated hospitals. Unilateral and asymptomatic, all lesions were situated near the angle of the mandible, except for the one case that involved the anterior portion of the mandible. The mean age of the patients was 53 years with a range of 31 to 78 years, and included 22 men and 2 women. In this report, radiographic interpretation of the lesion was done, and a radiographic classification was made as follows:

1. (Indentation type): The inferior border of the mandible is involved.
2. (Medium type): The lesion is situated above the inferior border of the mandible but below the mandibular canal.
3. (Deviation type): Deviation of the mandibular canal is suspected.
4. (Anterior type): The radiolucency is located in the anterior portion of the mandible.

     

Adhesion of N-methacryloyl-omega-amino acid primers to collagen analyzed by 13C NMR

Previously, we reported that the strength of the interaction between N-methacryloyl-omega-amino acid (NMomegaA) primers and dentinal collagen exhibited a strong correlation with the bond strength of the resin to etched dentin. To determine the pertinent functional groups of the amino acid residues in the dentinal collagen, to which the amide and/or the carboxylic acid groups of the NMomegaAs are adsorbed, we used 13C NMR techniques--primarily through the observation of spin-lattice relaxation times, Ti--to investigate the adsorption characteristics resulting from the interaction of NMomegaAs with a model oligopeptide for collagen, (PPG)5. The addition of NMomegaAs to a collagenous solution resulted in a decrease in the T1 values of the carbonyl carbons attributed to the carboxylic acid of the C-terminal Gly and to the third amide of the N-terminal Pro residues in the (PPG)5 molecule, thus reflecting the formation of hydrogen-bonded interactions.     

Dentin bonding agents: correlation of early bond strength with margin gaps

Tensile and shear bond strengths between restorative resin and flat human dentin surfaces were determined 15 min after polymerization of various resin systems in combination with 5 dentin bonding agents. The maximum marginal contraction gaps around cylindrical dentin cavities were measured for the same material combinations. A correlation was established for the linear relationship between the logarithm of the contraction gaps and the shear bond strength (r=−0.88). However, the rather wide 95% interval of prediction indicates that strength values do not adequately delineate the effectiveness of dentin bonding agents when used in cylindrical cavities. Early determination of bond strengths and gap widths is considered suitable to estimate the clinical efficacy of dentin bonding agents.