Comparison of the marginal adaptation of direct and indirect composite inlay restorations with optical coherence tomography

OBJECTIVE: The purpose of the study was to use the photonic imaging modality of optical coherence tomography (OCT) to compare the marginal adaptation of composite inlays fabricated by direct and indirect techniques. MATERIAL AND METHODS: Class II cavities were prepared on 34 extracted human molar teeth. The cavities were randomly divided into two groups according to the inlay fabrication technique. The first group was directly restored on cavities with a composite (Esthet X HD, Dentsply, Germany) after isolating. The second group was indirectly restored with the same composite material. Marginal adaptations were scanned before cementation with an invisible infrared light beam of OCT (Thorlabs), allowing measurement in 200 µm intervals. Restorations were cemented with a self-adhesive cement resin (SmartCem2, Dentsply), and then marginal adaptations were again measured with OCT. Mean values were statistically compared by using independent-samples t-test and paired samples t-test (p<0.05), before and after cementation. RESULTS: Direct inlays presented statistically smaller marginal discrepancy values than indirect inlays, before (p=0.00001442) and after (p=0.00001466) cementation. Marginal discrepancy values were increased for all restorations after cementation (p=0.00008839, p=0.000000952 for direct and indirect inlays, respectively). The mean marginal discrepancy value of the direct group increased from 56.88±20.04 µm to 91.88±31.7 µm, whereas the indirect group increased from 107.54±35.63 µm to 170.29±54.83 µm. Different techniques are available to detect marginal adaptation of restorations, but the OCT system can give quantitative information about resin cement thickness and its interaction between tooth and restoration in a nondestructive manner. CONCLUSIONS: Direct inlays presented smaller marginal discrepancy than indirect inlays. The marginal discrepancy values were increased for all restorations that refer to cement thickness after cementation

HIV-1 Neutralization Profile and Plant-Based Recombinant Expression of Actinohivin, an Env Glycan-Specific Lectin Devoid of T-Cell Mitogenic Activity

The development of a topical microbicide blocking the sexual transmission of HIV-1 is urgently needed to control the global HIV/AIDS pandemic. The actinomycete-derived lectin actinohivin (AH) is highly specific to a cluster of high-mannose-type glycans uniquely found on the viral envelope (Env). Here, we evaluated AH's candidacy toward a microbicide in terms of in vitro anti-HIV-1 activity, potential side effects, and recombinant producibility. Two validated assay systems based on human peripheral blood mononuclear cell (hPBMC) infection with primary isolates and TZM-bl cell infection with Env-pseudotyped viruses were employed to characterize AH's anti-HIV-1 activity. In hPMBCs, AH exhibited nanomolar neutralizing activity against primary viruses with diverse cellular tropisms, but did not cause mitogenicity or cytotoxicity that are often associated with other anti-HIV lectins. In the TZM-bl-based assay, AH showed broad anti-HIV-1 activity against clinically-relevant, mucosally transmitting strains of clades B and C. By contrast, clade A viruses showed strong resistance to AH. Correlation analysis suggested that HIV-1′s AH susceptibility is significantly linked to the N-glycans at the Env C2 and V4 regions. For recombinant (r)AH expression, we evaluated a tobacco mosaic virus-based system in Nicotiana benthamiana plants as a means to facilitate molecular engineering and cost-effective mass production. Biochemical analysis and an Env-mediated syncytium formation assay demonstrated high-level expression of functional rAH within six days. Taken together, our study revealed AH's cross-clade anti-HIV-1 activity, apparent lack of side effects common to lectins, and robust producibility using plant biotechnology. These findings justify further efforts to develop rAH toward a candidate HIV-1 microbicide

Water sorption of several bonding resins

Purposes: To determine, over the period of 1 month, (a) the degree of water sorption, and (b) the change in dimension, of four bonding resins and one low viscosity resin. Materials and Methods: Six specimens of bonding resin (Prisma Universal Bond 3, All-Bond 2, Bondwell LC, and LB Bond from the Clearfil Liner Bond II system) and a low viscosity resin (Protect Liner F) measuring 5 mm long, 5 mm wide and 3 mm thick were made. Each specimen was weighed immediately after curing and placed in distilled water at 37°C. Weights at 1, 2, 3, 7 days and 2, 3 and 4 weeks were obtained. Specimens were measured initially and at the above times. After 4 weeks, specimens were dried for 2 weeks and remeasured for size and weight. Then, the specimens were placed in a vacuum for approximately 4 hours and the weights and dimensions were remeasured. Values were converted to a mean percentage of the original dry weight and dimension and analyzed using one-way ANOVA and Fisher's PLSD test. Results: All materials absorbed most water in the first week. Prisma Universal Bond 3 stabilized within 2 days, LB Bond stabilized within the first week, whereas the remaining materials showed statistical increases in weight for 2-3 weeks (P < 0.05). After 4 weeks, LB Bond and All-Bond 2 resins demonstrated an approximate 8% weight increase, and the least increase was observed for Protect Liner F and Prisma Universal Bond 3 at about 3%. After desiccation, Protect Liner F and All-Bond 2 returned close to their original weight, and the remainder weighed less than initially. Dimensional changes were similar to changes in weight; LB Bond showed the greatest dimensional change over the 4 weeks (5%) and Protect Liner F the least change (1.5%).link_to_subscribed_fulltex

Meta-analysis of Bonding Effectiveness to Zirconia Ceramics

Dental zirconia can no longer be considered un-bondable to tooth tissue. In literature, an increasing number of papers indeed report on the bonding effectiveness of different luting techniques to zirconia. We aimed to disclose general trends in bonding to zirconia by systematically collecting zirconia bond-strength data. A search in PubMed and EMBASE revealed 1,371 bond-strength tests reported on in 144 papers. A macro-shear bond-strength protocol was most frequently used; it revealed significantly lower bond strengths and was less discriminative than the other test methods. Regarding luting technique, the combination of mechanical and chemical pre-treatment appeared particularly crucial to obtain durable bonding to zirconia ceramics. The cement choice was not revealed as a determining factor after aging conditions, as long as composite cement was used. Regarding test protocol, a tensile test appeared more discriminative, particularly when combined with 'water storage' aging.status: publishe

In vivo adhesive interface between resin and dentin.

V-shaped cervical cavities prepared in monkey teeth were restored with several dentin bonding systems, and the in vivo resin-dentin interfacial structures were observed under the scanning electron microscope using an argon-ion etching technique. The hybrid layer could be clearly observed; its depth was dependent on the conditioner/primer used and tended to be thinner at the deep part of the cavity. Resin tags were also clearly observed, and their structure at the inner part was noted to be rougher than that closer to the tubule orifices. When 37% phosphoric acid gel was used, the tags in the deeper parts of the cavity were much rougher. Hemispherical and spherical roughened structures were observed directly above the tubule orifices, which were thought to be a mixture of dentinal fluid and bonding resin that had flowed out from the tubules. The acidic primer containing maleic acid and HEMA could not remove the smear plugs, and undissolved smear particles were observed in the tubules.link_to_subscribed_fulltex

Opacity and color changes of tooth-colored restorative materials

Internal opacity and color changes of several esthetic direct restorative materials were determined using an accelerated test proposed by Asmussen (1981). Five chemically cured composites, seven light-cured composites, and three resin-modified glass-ionomer cements were placed in acrylic rings. After curing, they were left at 37°C for 1 week before baseline measurement, and then stored in 60°C distilled water up to 4 weeks. Color change was determined by a color analyzer, and contrast ratio representing opacity was calculated. All chemically cured composites tested discolored to dark yellow or dark brown after 4 weeks. Opacity decreased for two macrofilled composites. Light-cured composites discolored slightly, but their opacity change was negligible. All resin-modified glass-ionomer cements tested showed an abrupt decrease of opacity at the initial stage, accompanying darkening of the materials. Opacity decrease was found to be a factor of discoloration for some tooth-colored restorative materials, might be caused by a refractive index change of the matrix phase of the materials. ©Operative Dentistry, 1996.link_to_subscribed_fulltex