Accuracy of direct digital radiography for detecting occlusal caries in primary teeth compared with conventional radiography and visual inspection: an in vitro study

Objectives: The diagnosis of caries lesions is still a matter of concern in dentistry. The diagnosis of dental caries by digital radiography has a number of advantages over conventional radiography; however, this method has not been explored fully in the field of paediatric dentistry. This in vitro research evaluated the accuracy of direct digital radiography compared with visual inspection and conventional radiography in the diagnosis of occlusal caries lesions in primary molars. Methods: 50 molars were selected and evaluated under standardized conditions by 2 previously calibrated examiners according to 3 diagnostic methods (visual inspection, conventional radiography and direct digital radiography). Direct digital radiographs were obtained with the Dixi3 system (Planmeca, Helsinki, Finland) and the conventional radiographs with InSight film (Kodak Eastman Co., Rochester, NY). The images were scored and a reference standard was obtained histologically. The interexaminer reliability was calculated using Cohen`s kappa test and the specificity, sensitivity and accuracy of the methods were calculated. Results: Examiner reliability was good. For lesions limited to the enamel, visual inspection showed significantly higher sensitivity and accuracy than both radiographic methods, but no significant difference was found in specificity. For teeth with dentinal caries, no significant differences were found for any parameter when comparing visual and radiographic evaluation. Conclusions: Although less accurate than the visual method for detecting caries lesions confined to the enamel, the direct digital radiographic method is as effective as conventional radiographic examination and visual inspection of primary teeth with occlusal caries when the dentine is involved. Dentomaxillofacial Radiology (2010) 39, 362-367. doi: 10.1259/dmfr/22865872

Direct comparison of the bond strength results of the different test methods: A critical literature review

Objective. The goal of this paper is to undertake a literature search collecting all dentin bond strength data obtained for six adhesives with four tests ( shear, microshear, tensile and microtensile) and to critically analyze the results with respect to average bond strength, coefficient of variation, mode of failure and product ranking. Method. A PubMed search was carried out for the years between 1998 and 2009 identifying publications on bond strength measurements of resin composite to dentin using four tests: shear, tensile, microshear and microtensile. The six adhesive resins were selected covering three step systems ( OptiBond FL, Scotch Bond Multi-Purpose Plus), two-step (Prime & Bond NT, Single Bond, Clear. l SE Bond) and one step (Adper Prompt L Pop). Results. Pooling results from 147 references showed an ongoing high scatter in the bond strength data regardless which adhesive and which bond test was used. Coefficients of variation remained high (20-50%) even with the microbond test. The reported modes of failure for all tests still included high number of cohesive failures. The ranking seemed to be dependant on the test used. Significance. The scatter in dentin bond strength data remains regardless which test is used confirming Finite Element Analysis predicting non-uniform stress distributions due to a number of geometrical, loading, material properties and specimens preparation variables. This reopens the question whether, an interfacial fracture mechanics approach to analyze the dentin - adhesive bond is not more appropriate for obtaining better agreement among dentin bond related papers. (C) 2009 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

A direct composite resin stratification technique for restoration of the smile

Composite resins can be used to improve the esthetics of the smile at a low cost and with relatively high clinical performance, The aim of this article was to describe an approach to restore and enhance the esthetic appearance of the anterior dentition through vital tooth whitening and the direct layering of composite resin during predictable esthetic procedures, (Quintessence lot 2011;42205-211)

Direct and transdentinal antibacterial activity of chlorhexidine

Purpose: To evaluate the antibacterial effect of different chlorhexidine (CHX) concentrations against Streptococcus mutans using the agar-diffusion method with and without human dentin discs placed between the bacteria and the test substances. Methods: For the direct application (agar-well technique), a base layer containing 15 mL of BHI agar and 300 mu L. of S. mutans inoculum (10(9) cfu/mL) was prepared in Petri dishes. Six wells per dish were made at equidistant points and immediately filled with CHX gels (0.12%, 0.2%, 1% and 2%), 35% phosphoric acid and pure natrosol (n=6 wells/substance). Paper discs soaked in sterile distilled water served as control group (n=6). For the indirect application (transdentinal diffusion), 0.2 mm- and 0.5 mm-thick human dentin discs (36 discs/thickness) had the hydraulic conductance determined, which allowed the homogeneous allocation of them to the experimental and control groups. The discs were placed at equidistant points on the Petri dishes containing BHI with the S. mutans inoculum (six discs per dish; one per substance) with the pulpal side in contact with the bacteria. In the discs treated with CHX gels, dentin surface was etched with H(3)PO(4) and rinsed with distilled water before CHX gel application for 1 minute. After both direct and indirect application, the dishes were incubated for 24 hours and the bacterial growth inhibition zones formed around the wells and dentin discs were measured. Data were analyzed statistically by the non-parametric Kruskal-Wallis and Mann-Whitney tests at 5% significance level. Results: In the direct test, all CHX concentrations presented a dose-dependent antibacterial activity against S. mutans. In the indirect test, there were statistically significant differences (P< 0.05) among all groups and the largest microbial growth inhibition zones were observed when 2% CHX was applied on 0.2 mm-thick discs (P< 0.05). It was concluded that all evaluated CHX gels exhibited both direct and transdentinal antibacterial activity against S. mutans. This effect of CHX was strongly influenced by the CHX concentration as well as the dentin barrier thickness. (Am J Dent 2010;23:255-259).

On the direct product of two weak uniquely completable partial latin squares

In this note we show by counter-example that the direct product of two weak uniquely completable partial latin squares is not necessarily a uniquely completable partial latin square. This counter-example rejects a conjecture by Gower (see [3]) on the direct product of two uniquely completable partial latin squares.

The role of illness, resources, appraisal, and coping strategies in adjustment to HIV/AIDS: The direct and buffering effects

This study examined the utility of a stress and coping model of adjustment to HIV/AIDS. A total of 114 HN-infected gay or bisexual men were interviewed and they completed self-administered scales. Predictors included illness variables (disease stage and number of symptoms), coping resources (optimism and social support), appraisal (threat, challenge, and controllability), and coping strategies (problem-and emotion-focused). Adjustment outcomes were depression, global distress, social adjustment, and subjective health status. Results from hierarchical regression analyses indicated that better adjustment was related to an asymptomatic illness stage, fewer HN-related symptoms, greater social support, challenge and controllability appraisals, problem-focused coping, and lower threat appraisals and reliance on emotion focused coping. There was limited support for the stress-buffering effects of optimism. Findings support the utility of a stress and coping model of adjustment to HIV/AIDS.

Specification, refinement and verification of concurrent systems - An integration of Object-Z and CSP

This paper presents a method of formally specifying, refining and verifying concurrent systems which uses the object-oriented state-based specification language Object-Z together with the process algebra CSP. Object-Z provides a convenient way of modelling complex data structures needed to define the component processes of such systems, and CSP enables the concise specification of process interactions. The basis of the integration is a semantics of Object-Z classes identical to that of CSP processes. This allows classes specified in Object-Z to he used directly within the CSP part of the specification. In addition to specification, we also discuss refinement and verification in this model. The common semantic basis enables a unified method of refinement to be used, based upon CSP refinement. To enable state-based techniques to be used fur the Object-Z components of a specification we develop state-based refinement relations which are sound and complete with respect to CSP refinement. In addition, a verification method for static and dynamic properties is presented. The method allows us to verify properties of the CSP system specification in terms of its component Object-Z classes by using the laws of the the CSP operators together with the logic for Object-Z.

Latin interchanges and direct products

In this paper we focus on the identification of latin interchanges in latin squares which are the direct product of latin squares of smaller orders. The results we obtain on latin interchanges will be used to identify critical sets in direct products. This work is an extension of research carried out by Stinson and van Rees in 1982.

The first non-turnover voltammetric response from a molybdenum enzyme: direct electroscopy of dimethylsulfoxide reductase from Rhodobacter capsulatus

The first direct voltammetric response from a molybdenum enzyme under non-turnover conditions is reported. Cyclic voltammetry of dimethylsulfoxide reductase from Rhodobacter capsulatus reveals a reversible Mo-VI/V response at + 161 mV followed by a reversible Mo-V/IV response at -102 mV versus NHE at pH 8. The higher potential couple exhibits a pH dependence consistent with protonation upon reduction to the Mo-V state and we have determined the pK(a) for this semi-reduced species to be 9.0. The lower potential couple is pH independent within the range 5 < pH < 10. The optical spectrum of the Mo chromophore has been investigated with spectroelectrochemistry. At high potential, in its resting state, the enzyme exhibits a spectrum characteristic of the Mo-VI form. This changes significantly following bulk electrolysis (-400 mV versus NHE) at an optically transparent, indium-doped tin oxide working electrode, where a single visible electronic maximum at 632 nm is observed, which is comparable with spectra reported previously for the dithionite-reduced enzyme. This two-electron process is chemically reversible by reoxidizing the enzyme at the electrode in the absence of mediators or promoters. The activity of the enzyme has been established by observation of a catalytic current in the presence of DMSO at pH 8, where a sigmoidal (steady state) voltammogram is seen. Electronic supplementary material to this paper (Fig. S 1) can be obtained by using the Springer Link server located at http://dx.doi.org/10.1007/s00775-002-0374-y.

A refinement calculus for logic programs

Existing refinement calculi provide frameworks for the stepwise development of imperative programs from specifications. This paper presents a refinement calculus for deriving logic programs. The calculus contains a wide-spectrum logic programming language, including executable constructs such as sequential conjunction, disjunction, and existential quantification, as well as specification constructs such as general predicates, assumptions and universal quantification. A declarative semantics is defined for this wide-spectrum language based on executions. Executions are partial functions from states to states, where a state is represented as a set of bindings. The semantics is used to define the meaning of programs and specifications, including parameters and recursion. To complete the calculus, a notion of correctness-preserving refinement over programs in the wide-spectrum language is defined and refinement laws for developing programs are introduced. The refinement calculus is illustrated using example derivations and prototype tool support is discussed.

Transducer for direct measurement of skin friction in hypervelocity impulse facilities

An acceleration compensated transducer was developed to enable the direct measurement of skin friction in hypervelocity impulse facilities. The gauge incorporated a measurement and acceleration element that employed direct shear of a piezoelectric ceramic. The design integrated techniques to maximize rise time and shear response while minimizing the affects of acceleration, pressure, heat transfer, and electrical interference. The arrangement resulted in a transducer natural frequency near 40 kHz. The transducer was calibrated for shear and acceleration in separate bench tests and was calibrated for pressure within an impulse facility. Uncertainty analyses identified only small experimental errors in the shear and acceleration calibration techniques. Although significant errors were revealed in the method of pressure calibration, total skin-friction measurement errors as low as +/-7-12% were established. The transducer was successfully utilized in a shock tunnel, and sample measurements are presented for flow conditions that simulate a flight Mach number near 8.