An In Vitro Comparison of Shear Bond Strength for Heated Composite Resin With Three Conventional Luting Cements.

Background: This research set out to collate and contrast three popular luting agents-heated composite resin, resin-modified glass ionomer cement (RMGIC), and resin cement, and light-cure resin cement by measuring their shear bond strengths. Shear bond strength was measured between lithium disilicate discs (IPS E-max) and specimens luted with heated composite resin (Tetric N-Ceram, Ivoclar Vivadent), self-adhesive resin cement (3M ESPE Rely X U200), light-activated resin cement (Rely X Veneer cement), and resin-modified glass ionomer cement (Fuji Plus, GC America). A comparison was made between the shear bond strength of standard luting cement and heated composite resin on lithium disilicate discs. MATERIALS AND METHODS: Forty-eight lithium disilicate disc samples are collected and put on acrylic blocks for this investigation. To improve luting cement adhesion, the discs are etched with 5% hydrofluoric acid (HF) gel. For easier handling and lower viscosity during luting, the composite resin is heated to between 55 and 68°C on a digital wax melter. Shear bond strength tests were executed with the universal testing device after the following luting cement was applied in the center of the test specimen (lithium disilicate discs). Statistics software was used for the calculations and analysis. RESULTS: In accordance with the findings of the tests, shear bond strengths ranged from 2.2851 ± 0.5901 for nanohybrid composite resin to 7.3740 ± 0.6969 for self-adhesive resin cement and 4.4647 ± 0.9774 for light-activated resin cement. A statistically significant (p≤0.001) difference between the groups was found. Mean shear bond strength was significantly highest in the self-adhesive resin cement group, followed by the light-activated resin cement group, resin-modified GIC, and least with the nanohybrid composite resin group. CONCLUSION: Composite resins; in fixation of indirect restorations can have their viscosity reduced by preheating in a device, but they must be employed as soon as possible after removal. Standardizing the methods of heating composite resins for cementation is necessary to achieve desirable outcomes and direct the physician in their application. Although preheating composite resins for luting operations can be utilized to decrease the material's viscosity and enhance the restoration setting; it may not increase bond strength.

A Chemoproteomics Approach to Determine the Mechanism of Testicular Toxicity for the Bruton's Tyrosine Kinase Inhibitor CC-292.

During drug development, potential safety issues can occur at any time. Understanding the cause of a toxicity can help with deciding on how to advance the drug development program. Chemoproteomics provides a way to help understand the cause of a toxicity wherein the affected tissue is accessible and can be probed with a covalently binding compound that is analogous to the offending drug. In this case, N-(3-(5-fluoro-2-(4-(2-methoxyethoxy)phenylamino)pyrimidin-4-ylamino)phenyl)acrylamide (CC-292), a covalently binding Bruton's tyrosine kinase inhibitor, had produced testicular toxicity in rodents. Experiments were conducted using a CC-292 analog that could be chemically modified with biotin to probe rodent testes homogenates for potential binding sites that were subsequently recovered with avidin beads. These biotin-tagged proteins undergo trypsin digest on the avidin beads to yield peptides that are identified using mass spectrometry. Two proteins were identified from the testicular homogenates of both rats and mice, namely retinal dehydrogenase 1 (ALDH1A1) and retinal dehydrogenase 2 (ALDH1A2). Literature confirmed a link between inhibition of these enzymes and testicular toxicity. Subsequently, molecular modeling was used to demonstrate that CC-292 can be docked into both the nicotinamide adenine dinucleotide and retinal binding pockets of the analogous human ALDH1A2 enzyme. These data suggest that the off-target binding site for CC-292 on retinal dehydrogenase enzymes may provide a mechanistic explanation to the testicular toxicity observed in rodents and that there may be a potential concern for human male fertility. SIGNIFICANCE STATEMENT: Biotinylated covalently binding drug analogues are used to enrich bound proteins from tissue homogenates wherein toxicity was observed in rodents. Bound proteins were subsequently identified by mass spectroscopy. Competition of the analog binding with the parent inhibitor itself and three-dimensional molecular modeling were used to establish a likely link between the off-targets of CC-292, ALDH1A1, and ALDH1A2 with potential testicular toxicity.

Management of a malposed dental implant in the esthetic zone.

With the increased research in the field of dental implantology, there has been an extensive rise in the application of dental implants in various clinical situations. Complications arise with the frequent increase in the placement of dental implants; one of the common difficulties faced is placement of a malposed dental implant. Rehabilitation of prosthetically unfavorable implant is a serious challenge to a restorative dentist, a laboratory technician, and the patient. This is of great concern especially when it is in the maxillary smile zone. Prosthetic modifications, surgical corrections, or combination of both may be required in such situations. This case report describes a severely malposed dental implant in the maxillary left lateral incisor region in which an esthetically satisfactory result may not be feasible with prosthetic corrections alone. Hence, a surgical approach termed partial segmental osteotomy was initiated to reestablish the osseointegrated implant segment to a more favorable position before prosthetic phase.

Denture Adhesives in Prosthodontics: An Overview.

The use of denture adhesives is common among denture wearers, and it is also prescribed by many dentists. Prescribing denture adhesives has been viewed by many prosthodontists as a means of compensating for any defects in the fabrication procedures. Denture adhesives add to the retention and thereby improve chewing ability, reduce any instability, provide comfort and eliminate the accumulation of food debris beneath the dentures. Consequently, they increase the patient's sense of security and satisfaction. However, obtaining the advice of the dental practitioner prior to the use of adhesives is a must.

Comparative evaluation of the efficiency of four ceramic finishing systems.

AIM: To compare the effect of four different finishing systems and diamond paste on ceramic roughness with the objectives of evaluating the roughness of ceramic surface of prepared specimens after abrasion, finishing and polishing. MATERIALS & METHODS: A total of 50 test specimens were fabricated in the form of discs of diameter 13mm and 0.6mm thickness. Test specimens were then randomly distributed into five groups of 10 and coded. All the test specimens were then abraded with 125µm diamond in unidirectional motion to create surface roughness that will simulate occlusal or incisal correction. The values were recorded and the specimens were then finished using the various finishing systems. multiple range tests by Duncan's procedure. One way Anova was used to calculate the p-value Results:After fini shing, the Ra,Rq,Rz and Rt values showed a tendency to decline to levels much inferior to the values obtained after the preparation of the specimens. Ra values of group III specimens were slightly higher and the increase was significant. The highest Rt value [5.29] obtained after polishing is below the lowest roughness values [7.42] obtained after finishing the specimens. CONCLUSIONS: Finishing and polishing procedures have a significant role in reducing the roughness of ceramics.Following abrasion with diamond point to simulate clinical adjustment the roughness values doubled when compared to the initial reading.Ra, Rq,Rz and Rt values suggest that Sof lex is the most efficient of all the systems tested followed by auto glazing.After the final diamond paste polishing, sof lex group specimens showed the best finish and auto glazed specimens showed a value almost as equal to the so flex group. How to cite this article: Aravind P, Razak PA, Francis PG, Issac JK, Shanoj RP, Sasikumar TP. Comparative Evaluation of the Efficiency of Four Ceramics Finishing Systems. J Int Oral Health 2013; 5(5):59-64.

Discovery of a potent and isoform-selective targeted covalent inhibitor of the lipid kinase PI3Kα.

PI3Kα has been identified as an oncogene in human tumors. By use of rational drug design, a targeted covalent inhibitor 3 (CNX-1351) was created that potently and specifically inhibits PI3Kα. We demonstrate, using mass spectrometry and X-ray crystallography, that the selective inhibitor covalently modifies PI3Kα on cysteine 862 (C862), an amino acid unique to the α isoform, and that PI3Kß, -γ, and -δ are not covalently modified. 3 is able to potently (EC(50) < 100 nM) and specifically inhibit signaling in PI3Kα-dependent cancer cell lines, and this leads to a potent antiproliferative effect (GI(50) < 100 nM). A covalent probe, 8 (CNX-1220), which selectively bonds to PI3Kα, was used to investigate the duration of occupancy of 3 with PI3Kα in vivo. This is the first report of a PI3Kα-selective inhibitor, and these data demonstrate the biological impact of selectively targeting PI3Kα.

Comparative evaluation of border molding, using two different techniques in maxillary edentulous arches - An in vivo study.

BACKGROUND: This study was undertaken to compare the retention between sectional border molding using low fusing greenstick compound and single step border molding using condensation silicone (putty) impression material in three stages- A. Immediately following border molding, B. After final impression and C. With the finished permanent denture base. MATERIALS & METHODS: In this study evaluation of retentive values of sectional border molding (Group I) (custom impression trays border molded with green stick compound ) and single step border molding (Group II) ( border molding with condensation silicone (putty) impression material ). In both techniques definitive wash impression were made with light body condensation silicone and permanent denture base with heat cure polymerization resin. RESULTS: Group II was significantly higher (mean=8011.43) than Group I (mean=5777.43) in test-A. The t-value (1.5883) infers that there was significant difference between Group I and Group II (p =0.15). Group I was significantly higher (mean=6718.57) than Group II (mean=5224.29) in test -B. The t-value (1.6909) infers that there was significant difference between Group I and Group II (p=0.17). Group II was higher (mean=4025.14) than Group I (mean=3835.07) in test -C. The t-value was 0.1239. But it was found to be statistically insignificant (p=0.005). CONCLUSION: Within the limitation of this clinical study border molding custom tray with low fusing green stick compound provided similar retention as compared to custom impression tray with condensation silicone in permanent denture base. How to cite this article: Yarapatineni R, Vilekar A, Kumar JP, Kumar GA, Aravind P, Kumar PA. Comparative evaluation of border molding, using two different techniques in maxillary edentulous arches - An in vivo study. J Int Oral Health 2013; 5(6):82-7 .