The psychedelic renaissance: the next trip for psychiatry?

The psychedelic research renaissance is gaining traction. Preliminary clinical studies of the hallucinogenic fungi, psilocybin, with psychological support, have indicated improvements in mood, anxiety and quality of life. A seminal, open-label study demonstrated marked reductions in depression symptoms in participants with treatment-resistant depression (TRD). The associated neurobiological processes involve alterations in brain connectivity, together with altered amygdala and default mode network activity. At the cellular level, psychedelics promote synaptogenesis and neural plasticity. Prompted by the promising preliminary studies, a randomized, double-blind trial has recently been launched across Europe and North America to investigate the efficacy of psilocybin in TRD. One of these centres is based in Ireland - CHO Area 7 and Tallaght University Hospital. The outcome of this trial will determine whether psilocybin with psychological support will successfully translate into the psychiatric clinic for the benefit of patients.

Emerging ceramic-based materials for dentistry

Our goal is to give an overview of a selection of emerging ceramics and issues for dental or biomedical applications, with emphasis on specific challenges associated with full-contour zirconia ceramics, and a brief synopsis on new machinable glass-ceramics and ceramic-based interpenetrating phase composites. Selected fabrication techniques relevant to dental or biomedical applications such as microwave sintering, spark plasma sintering, and additive manufacturing are also reviewed. Where appropriate, the authors have added their opinions and guidance.

Ceramic materials in dentistry: historical evolution and current practice

Dental ceramics are presented within a simplifying framework allowing for facile understanding of their development, composition and indications. Engineering assessments of clinical function are dealt with and literature is reviewed on the clinical behaviour of all-ceramic systems. Practical aspects are presented regarding the choice and use of dental ceramics to maximize aesthetics and durability, emphasizing what we know and how we know it.

Levitation, lift, and bidirectional motion of colloidal particles in an electrically driven nematic liquid crystal

We study electric-field-induced dynamics of colloids in a nematic cell, experimentally and by computer simulations. Solid particles in the nematic bulk create director distortions of dipolar type. Elastic repulsion from the walls keeps the particles in the middle of cell. The ac electric field reorients the dipoles and lifts them to top or bottom, depending on dipole orientation. Once near the walls, the colloids are carried along two antiparallel horizontal directions by nematic backflow. Computer simulations of the backflow agree with the experiment.

Electrorotation of colloidal particles in liquid crystals

We present the first observations of dc electric-field-induced rotational motion of finite particles in liquid crystals. We show that the electrorotation is essentially identical to the well-known Quincke rotation, which in liquid crystals triggers an additional translational motion at higher fields. In the smectic phase the translational motion is confined to the two-dimensional geometry of smectic layers, in contrast to the isotropic and nematic phases, where the particles can move in all three dimensions. We demonstrate that by a proper analysis of the electrorotation, one can determine the in-plane viscosity of smectic liquid crystals. This method needs only a small amount of material, does not require uniform alignment over large areas, and enables probing rheological properties locally.

Switchable broadband achromatic half-wave plate with nematic liquid crystals

We describe a broadband achromatic half-wave retarder for normally incident light of arbitrary polarization. The device consists of a stack of one nematic liquid-crystal cell with uniform alignment sandwiched between two twisted nematic layers that have identical twist angles (135 degrees) but different orientations of their surface alignment. As a specific application, for light with linear polarization at 45 degrees to the optic axis of the homogeneous cell the stack functions efficiently as an optical switch. The switch rotates the incident linear polarization by 90 degrees in the absence of an electric field. When sufficiently high voltage is applied to all three layers, the device produces a near-zero effect on the incident polarization. An achromatic response in the spectral range 400-700 nm is achieved for both activated and quiescent states.

Asymmetric transmissive behavior of liquid-crystal diffraction gratings

We have used computer simulations to predict that the beam-steering efficiency of a common liquid-crystal diffraction grating will depend on which side is presented to the incident beam. The finite-difference time-domain method and the Helmholtz-Kirchhoff diffraction integral were utilized to simulate the performance of an idealized configuration of the grating.

Restoration of p53 function in anaplastic Wilms' tumor

BACKGROUND/PURPOSE

Recent studies have reported a high incidence of p53 mutations in anaplastic Wilms' tumors (WT). Restoration of the normal p53 state by current gene therapy techniques is thus an attractive potential mode of therapy for this tumor, which is poorly responsive to standard therapy. The purpose of this study is to determine whether gene delivery of normal p53 is possible and to characterize the subsequent effect of restoring the wild-type p53 state.

METHODS

Anaplastic WT RM1 cells (mutant p53) were transduced with replication-deficient adenoviral vectors containing either the wild-type p53 gene (rAd-p53) or the gene encoding a green fluorescent protein (rAd-GFP). The transduction efficiency of adenovirus for RM1 cells was determined by flow cytometric analysis of rAd-GFP-transduced cells. The effect of p53 transduction on cell viability was evaluated using a colorimetric proliferation assay. Apoptosis was evaluated by labeling DNA breaks using a TUNEL assay (Apo-Direct kit).

RESULTS

Cells treated with increasing concentrations of viral particles relative to tumor cells (multiplicity of infection-MOI) showed a dose-dependent increase in the number of cells transduced. Twenty-four hours after viral treatment, the percentage of cells transduced for MOIs of 10, 50, 100, and 500 was 29.5, 60.9, 74.6, and 92.4, respectively; at 48 hours the percentage of cells transduced increased to 70.8, 90.7, 93. 7, and 96.3, respectively. Viral treatment at an MOI of 50 reduced cell proliferation by 10% at 17 hours and 97% at 5 days; at an MOI of 100, the relative reduction in proliferation was 15% and 99.8%, respectively. When assayed, 30% of cells became apoptotic at an MOI of 50, and 48% at an MOI of 100.

CONCLUSIONS

Highly efficient delivery of the p53 tumor suppressor gene by adenoviral vector to anaplastic WT is possible. Subsequent restoration of the normal p53 state results in reduced viability and increased apoptosis. Gene replacement of p53 may represent a novel therapeutic agent for anaplastic Wilms' tumors.

A study to examine the accuracy of potassium measurements in clinical laboratories across Canada

OBJECTIVE

To assess the accuracy of potassium measurements in clinical laboratories across Canada.

DESIGN AND METHOD

The flame atomic emission spectrophotometry reference method for the determination of potassium was established at the Canadian Reference Laboratory by using National Institute of Science and Technology standard reference materials. The method was subsequently used to assign target values for potassium to Canadian Reference Laboratory's External Quality Assessment human-serum-based testing material. A total of 503 laboratories participated and 9,279 individual External Quality Assessment test results were included in the study. Bias was determined by using difference plots.

RESULTS

Clinically significant bias (>1.6%) was observed in 45.9% of the laboratories. Bias ranged from 0.34 mmol/L to -0.54 mmol/L. At low concentrations (<3.5 mmol/L) a positive bias was most frequently observed (14.7% of analytical systems). At high potassium concentrations (>5.1 mmol/L) a negative bias was most frequently observed (31.4% of analytical systems).

CONCLUSION

Inaccuracy in potassium results can contribute to test redundancy and mismanagement of patients, while prohibiting the merger of laboratory data from disparate testing sites for the purpose of trending and consolidation within a "universal health record." Inaccurate test results and the lack of standardization among laboratories adversely impact our ability to establish common reference intervals and critical limits. This inability has an adverse effect on medical decisions and patient care.

Load-bearing behavior of a simulated craniofacial structure fabricated from a hydroxyapatite cement and bioresorbable fiber-mesh

Calcium phosphate cements (CPC) have proven successful in the repair of small, non-stress bearing skeletal defects. These cements do not have sufficient tensile strength or fracture toughness to allow their use in stress-bearing applications. It was hypothesized that a bioresorbable fiber mesh would improve the load-bearing behavior of shell structures fabricated of CPC. This study used a biaxial flexure fixture to compare the work-to-fracture values of discs made of: (1) CPC; (2) CPC reinforced with a bioresorbable two-dimensionally oriented poly(glactin) fiber-mesh; and (3) poly(methyl methacrylate) (PMMA) that were immersed in a serum-like solution for 0-28 days. CPC-mesh and PMMA discs were indistinguishable at 0, 1 and 7 days, based on work-to-fracture data. CPC and CPC-mesh discs were indistinguishable at day 28, because of fiber hydrolysis. The knitted fiber-mesh was effective in improving load-bearing behavior of a calcium phosphate cement for potential structural repair of bone defects.

Fracture toughness (KIc) of a dental porcelain determined by fractographic analysis

OBJECTIVES

Fractographic analysis of indentation cracks is performed following flexure testing as part of the ASTM (1999) standard for fracture toughness, KIc, determination in advanced ceramics. This method depends on the conduciveness of the material towards fractographic interpretation. The purpose of this study was to evaluate the use of fractography in fracture toughness methods with a feldspathic dental porcelain, in which KIc was measured fractographically as well as numerically using two controlled-flaw beam bending techniques.

METHODS

The following methods for KIc determination were applied to a dental porcelain containing a leucite volume fraction of 15-20%: (1) surface crack in flexure (SCF) (dependent upon fractographic analysis); and (2) indentation strength (IS) at indentation loads of 9.8 and 19.6 N (applying both standard numeric calculations and fractographic analysis). The testing environments were (1) ambient air (IS and SCF) and (2) flowing dry nitrogen (SCF).

RESULTS

No significant differences were found between numeric and fractographic KIc values for the IS technique at both indentation loads (9.8 and 19.6 N) in ambient air, although KIc values were sensitive to indentation load. Due to the presence of residual stresses, stable crack extension was observed fractographically in all IS specimens, as evidenced by differences between initial (ainitial) and critical (acritical) crack dimensions. For the SCF method, there was a significant difference in toughness between specimens tested in air versus dry nitrogen, however no fractographic evidence for chemically assisted slow crack growth (SCG) was observed.

SIGNIFICANCE

The SCF method as described by the ASTM standard was applicable to the feldspathic porcelain and produced very comparable results with the numeric toughness calculations of the IS procedure. However, fractographic analysis of the surface crack was somewhat difficult for this glassy ceramic compared with polycrystalline ceramics. Knowledge about stable crack extension or slow crack growth and its fractographic appearance is essential when estimating the toughness from examination of flaw dimensions on fractured surfaces since large calculation errors may occur if these effects are not taken into account.

Clinically relevant approach to failure testing of all-ceramic restorations

STATEMENT OF PROBLEM

One common test of single-unit restorations involves applying loads to clinically realistic specimens through spherical indenters, or equivalently, loading curved incisal edges against flat compression platens. As knowledge has become available regarding clinical failure mechanisms and the behavior of in vitro tests, it is possible to constructively question the clinical validity of such failure testing and to move toward developing more relevant test methods.

PURPOSE

This article reviewed characteristics of the traditional load-to-failure test, contrasted these with characteristics of clinical failure for all-ceramic restorations, and sought to explain the discrepancies. Literature regarding intraoral conditions was reviewed to develop an understanding of how laboratory testing could be revised. Variables considered to be important in simulating clinical conditions were described, along with their recent laboratory evaluation.

CONCLUSIONS

Traditional fracture tests of single unit all-ceramic prostheses are inappropriate, because they do not create failure mechanisms seen in retrieved clinical specimens. Validated tests are needed to elucidate the role(s) that cement systems, bonding, occlusion, and even metal copings play in the success of fixed prostheses and to make meaningful comparisons possible among novel ceramic and metal substructures. Research over the past 6 years has shown that crack systems mimicking clinical failure can be produced in all-ceramic restorations under appropriate conditions.

Indentation damage and mechanical properties of human enamel and dentin

Understanding the mechanical properties of human teeth is important to clinical tooth preparation and to the development of "tooth-like" restorative materials. Previous studies have focused on the macroscopic fracture behavior of enamel and dentin. In the present study, we performed indentation studies to understand the microfracture and deformation and the microcrack-microstructure interactions of teeth. It was hypothesized that crack propagation would be influenced by enamel rods and the dentino-enamel junction (DEJ), and the mechanical properties would be influenced by enamel rod orientation and tooth-to-tooth variation. Twenty-eight human third molars were used for the measurement of hardness, fracture toughness, elastic modulus, and energy absorbed during indentation. We examined the effect of enamel rod orientation by propagating cracks in the occlusal surface, and in the axial section in directions parallel and perpendicular to the occlusal surface. The results showed that the cracks in the enamel axial section were significantly longer in the direction perpendicular to the occlusal surface than parallel. The cracks propagating toward the DEJ were always arrested and unable to penetrate dentin. The fracture toughness of enamel was not single-valued but varied by a factor of three as a function of enamel rod orientation. The elastic modulus of enamel showed a significant difference between the occlusal surface and the axial section. It is concluded that the cracks strongly interact with the DEJ and the enamel rods, and that the mechanical properties of teeth are functions of microstructural orientations; hence, single values of properties (e.g., a single toughness value or a single modulus value) should not be used without information on microstructural orientation.

Enamel subsurface damage due to tooth preparation with diamonds

In clinical tooth preparation with diamond burs, sharp diamond particles indent and scratch the enamel, causing material removal. Such operations may produce subsurface damage in enamel. However, little information is available on the mechanisms and the extent of subsurface damage in enamel produced during clinical tooth preparation. The aim of this study, therefore, was to investigate the mechanisms of subsurface damage produced in enamel during tooth preparation by means of diamond burs, and to examine the dependence of such damage on enamel rod orientation, diamond particle size, and removal rate. Subsurface damage was evaluated by a bonded-interface technique. Tooth preparation was carried out on two enamel rod orientations, with four clinical diamond burs (coarse, medium, fine, and superfine) used in a dental handpiece. The results of this study showed that subsurface damage in enamel took the form of median-type cracks and distributed microcracks, extending preferentially along the boundaries between the enamel rods. Microcracks within individual enamel rods were also observed. The median-type cracks were significantly longer in the direction parallel to the enamel rods than perpendicular to the rods. Preparation with the coarse diamond bur produced cracks as deep as 84 +/- 30 microns in enamel. Finishing with fine diamond burs was effective in crack removal. The crack lengths in enamel were not significantly different when the removal rate was varied. Based on these results, it is concluded that subsurface damage in enamel induced by tooth preparation takes the form of median-type cracks as well as inter- and intra-rod microcracks, and that the lengths of these cracks are sensitive to diamond particle size and enamel rod orientation, but insensitive to removal rate.

Compatibility of ceramic-ceramic systems for fixed prosthodontics

This study evaluated dilatometric data for predicting ceramic-ceramic compatibility for porcelains fired on central incisor copings (n = 72) of high expansion colored IPS-Empress porcelain. Nine body porcelains (leucite 0 wt% to 51 wt%) were each fired onto eight copings. Cracks were detected at 10 x magnification using transilluminating light. Failure was defined as the presence of at least one crack and probability of failure (Pf) as the ratio of failed to total crowns. Thermal contraction coefficients (alpha) were determined using four bars of each porcelain following the protocol of ISO 9693. Absolute differences in thermal contraction, magnitude of delta alpha, between core and test porcelains were plotted against Pf and curve fit. Significant differences in alpha were found among the porcelains tested (ANOVA, 95% Tukey); the alpha values ranged from 7.92 to 17.83 x 10(-6)/degree C; Pf ranged from 0 to 1. Compatible porcelains (no cracks during any firing of all eight crowns) had magnitude of delta alpha values less than 1 x 10(-6)/degree C. Absolute values (magnitude of delta alpha) were surprisingly predictive of Pf given the very different cooling rates (dilatometry versus dental lab) and the relatively complex crown shape. Standard dilatometry may be useful for predicting the compatibility of ceramic-ceramic systems. Three porcelains, IPS-Empress dentin, Duceram, and Will-Ceram were successfully used for veneering IPS Empress cores.

Contact damage as a failure mode during in vitro testing

PURPOSE

The purpose of this study was to identify the failure mode(s) for all-ceramic crowns tested in vitro and to determine whether measured failure loads in this type of testing would be influenced by indenter radii (a classic Hertzian cone-crack variable) and specimen thickness.

MATERIALS & METHODS

Fracture surfaces and failure probability data from glass-ceramic cuspids (n = 50) tested in a previous in vitro study were examined to determine their mode of failure. To further evaluate the failure mode identified for the crowns, 100 ceramic platelets (50 glass-ceramic, 50 feldspathic porcelain) were loaded to failure beneath spherical indenters (radii, 0.75-94 mm).

RESULTS

Glass-ceramic cuspids failed from blunt contact damage at the point of loading (with Hertzian stress-state damage evident). Ceramic platelets exhibited failure from either the indentation surface (Hertzian cone-cracking present) or from the supported surface (ie, mimicking bending failure). Failure-loads increased with the indenter radius for both failure modes. Failure from blunt contact damage occurred at markedly higher loads than did failure from support-surface sites.

CONCLUSIONS

Blunt indentation damage was identified as being the failure source for the glass-ceramic cuspid crowns and a major failure mode for both feldspathic porcelain and glass-ceramic platelets loaded beneath spherical indenters. This failure mode is not similar to that reported for clinically failed glass-ceramic crowns. Influential testing variables were contact radius, ceramic thickness, and the surface finish of both the ceramic specimen and test platen.

Ceramics in dentistry: historical roots and current perspectives

This article presents a brief history of dental ceramics and offers perspectives on recent research aimed at the further development of ceramics for clinical use, at their evaluation and selection, and very importantly, their clinical performance. Innovative ceramic materials and ceramics processing strategies that were introduced to restorative dentistry since the early 1980s are discussed. Notable research is highlighted regarding (1) wear of ceramics and opposing enamel, (2) polishability of porcelains, (3) influence of firing history on the thermal expansion of porcelains for metal ceramics, (4) machining and CAD/CAM as fabrication methods for clinical restorations, (5) fit of ceramic restorations, (6) clinical failure mechanisms of all-ceramic prostheses, (7) chemical and thermal strengthening of dental ceramics, (8) intraoral porcelain repair, and (9) criteria for selection of the various ceramics available. It is found that strong scientific and collaborative foundations exist for the continued understanding and improvement of dental ceramic systems.

In-Ceram failure behavior and core-veneer interface quality as influenced by residual infiltration glass

PURPOSE

Crown and fixed partial denture fabrication using In-Ceram all-ceramic restorative material (Vita Zahnfabrik, Bad Säckingen, Germany) involves the veneering of a glass-infiltrated alumina core with porcelain. The manufacturer instructs that excess infiltration glass be removed from all core surfaces before++ porcelain application; however, meticulous removal may not be practical. This study evaluates the failure behavior of two different types of In-Ceram structures with or without thin layers of excess infiltration glass left on core surfaces.

MATERIALS AND METHODS

Two groups of porcelain-veneered incisor crowns were fabricated having either (1) excess infiltration glass removed from the aluminous core (n = 10) or (2) a thin layer (0.1 to 0.3 mm) of excess glass remaining on the core (n = 10). Each crown was loaded on its incisal edge against a flat compression platen at 0.5 mm/min. Two groups of core disks (thickness, 1 mm; radius, 7.5 mm) underwent similar surface treatments; i.e., group A as recommended (n = 15) and group B having excess glass (n = 15). Disks were veneered with porcelain, polished to 1.5 mm, and loaded in biaxial flexure at 0.5 mm/min. All fracture surfaces were analyzed using light microscopy and a select sample were examined using scanning electron microscopy. A simple two-dimensional finite-element model was used to evaluate the stress state at the core-veneer interface of bend samples.

RESULTS

Failure loads were significantly higher for crowns having excess glass (Student's t test, P < .004). Weibull moduli were indistinguishable (m = 6.2) between crown groups, consistent with the microscopic impression that they shared a common failure mode. Microscopic evaluation of cross-sectioned crowns showed core-veneer interfaces with less porosity in the presence of excess infiltration glass. Failure loads for the disk groups were indistinguishable (Student's t test, P > .8). Scanning electron microscopic analysis of disk samples revealed that failures originated either at core-veneer interfaces or at lower disk surfaces, consistent with the finite-element analysis.

CONCLUSION

Excess infiltration glass on the core surface will not degrade the strength of In-Ceram structures. Central incisor crowns (as tested) were strengthened by excess infiltration glass, but disk samples (stressed differently) were not. Finite-element results suggest that disk failure originates from three possible sources.

Failure of all-ceramic fixed partial dentures in vitro and in vivo: analysis and modeling

Hertzian cone cracks visible at the loading site of 20 all-ceramic fixed partial dentures (FPDs), tested in vitro, led to the hypotheses that failure was due to the propagation of localized contact damage crack systems (Hertzian stress state) and that such damage was an unlikely clinical failure mode. Fractographic analysis of the 20 laboratory-failed and nine clinically-failed all-ceramic FPDs allowed for definitive testing of these hypotheses and a comparison between in vitro and in vivo failure behavior. In all cases, failure occurred in the FPD connectors (none from contact damage), with approximately 70 to 78% originating from the interface between the core and veneer ceramics. The coincidence between failure origins provides strong evidence that the in vitro test modeled aspects of structural behavior having clinical importance. The fractographic observations, coupled with the in vitro failure load data, furnished very specific boundary conditions which were applied to constrain mathematical models of FPD connector failure. Finite element analysis (FEA) of the laboratory FPDs found that maximum principal tensile stresses would occur at locations consistent with the fractographic observations only if: (1) there were appropriate elastic moduli differences between the ceramics; and (2) a small amount of abutment rotation was allowed. Weibull failure probability (Pf) calculations, incorporating FEA stress profiles, very closely replicated the laboratory failure distribution only when: (1) the veneer ceramic was much weaker than the core ceramic; and (2) the Weibull modulus of the core-veneer interface was much lower than that for the free veneer surface (i.e., the interface is of lower quality with regard to defects).(ABSTRACT TRUNCATED AT 250 WORDS)

Perspectives on strength

Strength values are often relied upon as indicators of structural performance for brittle dental materials. Strength, however, is more of a "conditional" than an inherent material property, and strength data alone cannot be directly extrapolated to predict structural performance. Strength data are meaningful when placed into context via knowledge of material microstructure, processing history, testing methodology, testing environment and failure mechanism(s). Structure failure is determined by additional failure probability variables (in concert with strength) that describe stress distributions, flaw size distributions, and that can account for either single or multiple failure modes. Lifetime predictions require additional information about the time dependence of slow crack growth. Basic fracture mechanics principles and Weibull failure modeling will be reviewed for the perspective they provide in understanding strength and the data obtained using various laboratory tests. Examples will be given to demonstrate how failed specimens can provide crucial information to either validate or question the failure mechanisms invoked during laboratory testing. The role of interfacial stresses is discussed as applied to dental structures of current interest. Overall, it is emphasized that an understanding of actual clinical failure modes is absolutely necessary before results of in vitro strength testing can be considered to have clinical validity.

In vitro fracture behavior of ceramic and metal-ceramic restorations

PURPOSE

Failed crowns and failure load data were studied to gain insights into the fracture behavior of prostheses under incisal-directed, load-to-failure testing.

MATERIALS AND METHODS

Incisor crowns (n = 68) were fabricated: two all-ceramic groups (feldspathic veneer on high-strength core), differing in core design, and two metal-ceramic groups, differing in metal oxidation time (30 seconds v 3 minutes). Crowns were loaded to failure on their incisal edge. Gross visual, microscopic, and elemental microprobe analyses of failed crowns were coupled with Weibull analysis of the failure load data.

RESULTS

Failure loads were higher for the normal oxidation time (TN) than for the extended oxidation time (TE) metal-ceramic crowns (P < .02), but both groups had indistinguishable Weibull moduli indicating the possibility of a common failure origin. Fracture behavior and Weibull results both implicated the oxide layer as being the origin of failure. The ratio of fracture loads (TE/TN) corresponded well with calculated oxide-volume ratios. Failure loads were lower for the all-ceramic than for the metal-ceramic crowns (P < .001). Fifty percent of the all-ceramic crowns failed by delamination of veneering glass alone, leaving a thin layer of residual glass on the core surface. Scanning electron microscope views showed that delamination occurred 10 to 50 microns away from the core-veneer interface. Electron microprobe elemental analysis of the core-veneer interface showed that residual core infiltration glass was not present on the core surface and that chemical alterations in the veneering glass were apparently limited to less than a 2- to 3-microns thick layer.

CONCLUSIONS

Failure for both restorative systems involved interfacial stresses with crack propagation occurring at or near the core-veneer interface. The weaker interface in the metal-ceramic system probably resulted from an increase in surface oxide volume, irrespective of any change in its adherence or physical properties. For the ceramic crowns, delamination crack fronts appeared to propagate through chemically unaltered veneering porcelain. Both the Weibull moduli and characteristic strengths were indistinguishable between either of the two ceramic core designs or between groups failing from delamination with or without core cracking/failure. This is consistent with delamination being the primary fracture process during failure. Clinical implications should not be drawn from results of this study because no correlation is known to have ever been established between clinical behavior and incisal load-to-failure results.

Overview and patient recruitment in the Adult Day Health Care Evaluation Study

Although Adult Day Health Care (ADHC) is increasingly prominent in the continuum of long-term care services, the results from previous studies of the effects of ADHC are mixed. The objectives of the ADHC Evaluation Study were to determine the effect of ADHC on health status, utilization, and cost of care. The first phase was a randomized controlled trial evaluating ADHC provided directly by the VA. Patients at four medical centers (n = 826) were randomly assigned to receive either ADHC or customary care, and outcomes were compared for the two groups. The second phase was a prospective cohort study evaluating ADHC provided under contract to community agencies in which patients at four additional medical centers (n = 163) were assigned to contract ADHC programs. Outcomes were compared with those of similar patients in the randomized trial. Patients and care givers were assessed at intake and 6 and 12 months after intake. To be admitted to the study, patients must have met one of the following criteria: residence in a nursing home; dependence in ambulation, dressing, or toileting; bowel incontinence; or significant cognitive impairment. Patients at intake demonstrated major impairment in function and high levels of prior use of health care services.

The Adult Day Health Care Evaluation Study--impact on VA programs

The research study in Adult Day Health Care (ADHC) has had a fourfold impact on the Veterans Administration: 1) It defined the health care focus of ADHC and shaped consequent program design; 2) It forged a partnership between research and clinical staff in ADHC programmatic development; 3) It enhanced the perception of research in program development in long-term care; and 4) It provided VA with direction for program redesign to render ADHC more cost-effective. With careful planning, the program is expected to grow in the future as a part of VA's continuum of long-term care programs.

Summary and discussion of methods and results of the Adult Day Health Care Evaluation Study

This article summarizes the study results and presents an evaluative summary of the implementation of study methods designed to provide guidance in the degree of confidence with which the results may be accepted and generalized to other situations. Patients who were offered VA-ADHC services in the first phase of this study had significantly higher VA health care costs on average than patients assigned to customary care, with no apparent incremental health benefit to themselves or their care givers. One can have a high level of confidence in these results. The ADHC clinical services were implemented as planned, the randomized controlled trial was implemented successfully, and such threats to validity as insufficient numbers of patients and differential attrition were not present. Certain subgroups of patients assigned to VA-ADHC had VA costs of care that were not significantly higher than those assigned to customary care, although these results must be interpreted with caution. The findings of the second phase of the study evaluating contract ADHC provide no support for choosing to provide either contract ADHC or VA-ADHC over the other. The nonrandomized design and smaller sample size suggest that inferences from the contract ADHC evaluation should be drawn with more caution than those from the VA-ADHC evaluation.

Implications of the Adult Day Health Care Evaluation Study for program revision and research

With no additional effort to revise adult day health care (ADHC) services or the types of patients who receive them, it would appear that adding an ADHC program to a VA Medical Center would not achieve the desired objectives. The authors discuss here the advantages, disadvantages, and feasibility of 2 options for program revision. The first is to target ADHC to those types of patients who may be most likely to benefit. A targeting scheme should use the most objective criteria possible and may need to be implemented as part of a case-managed package of community-based services. The second option for program revision is to reduce the costs of ADHC services. A cost model developed as a part of the study demonstrated the effect of possible revisions, including increasing enrollment, reducing staffing costs, decreasing length of stay in ADHC, and increasing substitution of ADHC for other services. These changes differ in the level of administrative support and clinician behavior change needed for their implementation. This report then concludes with a discussion of the implications of the results for implementation of VA-ADHC versus contract ADHC, and a discussion of possible directions for future research.

Ordinary retirement: commonalities and continuity

Case studies of twenty-five recent retirees from a Midwest plant are the basis for a profile of ordinary retirement. The commonalities of preparation, satisfaction, activity patterns, and relationships are found to far outweigh differences. Exceptions are the widowed, divorced, and those with health disabilities.

Adult day health care evaluation study: methodology and implementation. Adult Day Health Care Evaluation Development Group

The Adult Day Health Care Evaluation Study was developed in response to a congressional mandate to study the medical efficacy and cost effectiveness of the Adult Day Health Care (ADHC) effort in the Department of Veterans Affairs (VA). Four sites providing ADHC in VA facilities are participating in an ongoing randomized controlled trial. Three years of developmental work prior to the study addressed methodological issues that were problematic in previous studies. This developmental work resulted in the methodological approaches described here: (1) a patient recruitment process that actively recruits and screens all potential candidates using empirically developed admission criteria based on predictors of nursing home placement in VA; (2) the selection and development of measures of medical efficacy that assess a wide range of patient and caregiver outcomes with sufficient sensitivity to detect small but clinically important changes; and (3) methods for detailed, accurate, and efficient measurement of utilization and costs of health care within and outside VA. These approaches may be helpful to other researchers and may advance the methodological sophistication of long-term care program evaluation.

A model for reducing the cost of care in VA medical centers that offer adult day health care

One approach to providing cost-effective adult day health care (ADHC) services is to guide both the inputs to ADHC services and the provision of other services so that substitution for institutional services can realistically take place. This approach has been used in a randomized clinical trial to evaluate the medical efficacy and cost of ADHC in the Department of Veterans Affairs (DVA). This article describes the strategies that were used to improve the cost effectiveness of ADHC during the evaluation. Cost and use estimates were developed based on the best data available from the DVA and previous research on the cost for patients' use of ADHC, nursing home, hospital, and ambulatory care. A cost workshop was attended by the ADHC managers to develop plans for controlling costs. Plans were identified that increase the likelihood that ADHC can be shown to be less costly than customary care.

Fracture surface analysis of dental ceramics: clinically failed restorations

Fractography was used to study all-ceramic restorations that had failed clinically. Some basic tenets of fracture mechanics and fractography are reviewed and related to the examination of clinically failed all-ceramic restorations. Dicor and Cerestore restorations that had failed either at trial placement or 17 to 36 months postcementation were evaluated. Failed Dicor restorations were studied to determine the origin of failure and calculate the intraoral stress at failure. Descriptive information regarding crack origin and crack path were obtained from failed restorations constructed of first-generation Cerestore. A majority of the crowns apparently failed from the internal surface, indicating this as the highest tensile surface and/or the location of the largest flaws. Flaws were identified as being related to fabrication or inherent in the ceramic microstructure.

Fracture-surface analysis of dental ceramics

This study demonstrated that quantitative fractography can be used to study failed aluminous and glass-ceramic central porcelains. Fracture surfaces of DICOR and Vitadur-N core porcelain modulous-of-rupture bars were studied to identify fracture mirror features useful in (1) locating the source of fracture and (2) calculating the stress at fracture in clinically failed restorations. The morphology of fracture surfaces results from events related to the initiation and propagation of the crack front during failure. Modulus-of-rupture testing was performed in four-point bending. Fracture surfaces were studied by scanning electron microscopy. The mean fracture stress for the Vitadur-N porcelain was 94.7 +/- 12.4 MPa (13,730 psi); for DICOR the fracture stress was 55.4 +/- 10.6 MPa (8,030 psi). The standard quantitative fractography relationship between in mirror radius and ln fracture stress was followed for both materials. This quantitative fractography relationship was used to calculate the in vivo stress at failure in a clinically fractured DICOR molar crown. Five clinically failed DICOR crowns were seen to fail from the internal surface.

Influence of surface preparation on the strength and surface microstructure of a cast dental ceramic

The effect of three surface preparations on the flexural strength of a cast glass-ceramic (Dicor) was studied. The microstructure of the external and fracture surfaces was evaluated using electron microscopy. It was found that there was no difference in strength for the "as-cast/cerammed," acid-etched, or glazed shading porcelain specimens. A significant increase in strength (twofold) was observed when the "ceram layer" was mechanically removed from the surface of the ceramic. Scanning electron microscopy revealed that the "ceram layer" was 25 to 100 microns thick and consisted of crystal "whiskers" oriented perpendicular to the external surfaces. It was observed in both the laboratory and the clinically failed specimens that a zone of strength-limiting porosity was associated with this "ceram layer." Potential origins of the crystal "whiskers" and the porosity were discussed.

Use of an elastomeric material to improve the occlusal seat and marginal seal of cast restorations

A method to improve the fit of castings by the use of a light-bodied condensation silicone impression material was tested. Eighteen-full coverage castings were made on individual resin dies and divided into two groups. The experimental group was adjusted internally to a uniform precementation space by using the silicone impression material as a disclosing agent for binding of the castings on the axial or occlusal walls. Measurements of marginal fit were made with a light microscope using a filar eyepiece both externally and internally by sectioning after cementation with a zinc phosphate cement. Results demonstrated a significant improvement in marginal seal and occlusal seating in the experimental group compared with the control group. The condensation silicone material proved to be an appropriate research tool for nondestructive, three-dimensional evaluation of the postcementation space and offers a new method of evaluation of cement thickness because seating was found to be not significantly different from that with zinc phosphate cement.

Nondestructive, three-dimensional internal fit mapping of fixed prostheses

Crown fit may be three-dimensionally mapped by using a nondestructive optical technique. Reflected light transmission through thicknesses of a colored impression material was shown to follow the Beer-Lambert relationship over a range of approximately 10 to 300 microns, a useful range of interest for study of cement layer thickness. Control thicknesses of impression material were first formed between the measuring platens of a micrometer, and light transmission values (relative reflections) were measured through these control thicknesses of impression material held against air-abraded, noncast gold alloy. Relative reflection values were similarly measured from impression material formed inside cast gold crowns seated on their respective dies and these values were plotted against direct thickness measurements by using the Beer-Lambert relationship. It was established that the micrometer-produced control specimens yielded a valid standard curve for use with the cast gold crowns. Precementation space measurements determined photometrically were found to correlate significantly (r = 0.72, p less than 0.001) with zinc phosphate cement thickness measured on subsequently cemented and cross-sectioned crowns. A three-dimensional representation of the precementation space inside one crown was developed after mapping of 45 points in less than 5 minutes.

Social integration, leisure activity, and life satisfaction in older adults: activity theory revisited

The relative contributions of objective integration, subjective integration, and total leisure activity to the life satisfaction of older adults are examined. A random sample of 400 persons ages forty through eighty-nine residing in a demographically typical midwestern city were interviewed by phone. Results show that Objective Integration does not contribute incrementally to Life Satisfaction except among males under age sixty-five. Subjective Integration, on the other hand, contributes significantly to Life Satisfaction of males and females under and over age sixty-five. Even when demographic variables, Objective Integration, and Subjective Integration are taken into account statistically, Total Leisure Activity contributes significantly to Life Satisfaction in all groups examined.

Evaluation of biangular reflection photometry for quantitative study of etched alloy surface roughness

Biangular reflection photometry was correlated with quantitative stereology and direct pit-depth measurements for an electrolytically etched nickel-chromium-beryllium alloy. Effects of viewing angle, viewing aperture, and plane polarization of incident and viewing light were also studied. The results showed that architectural changes in the etched metal surface could be quantitatively described with the use of reflection photometry. An off-specular peak, located at an angle of reflection considerably different from the angle of incidence, was observed to have an intensity comparable with that of the specular reflection peak. Viewing aperture was found to affect one's ability to distinguish among degrees of surface roughness.

Effect of the Today contraceptive sponge on growth and toxic shock syndrome toxin-1 production by Staphylococcus aureus

Toxic-shock syndrome toxin-1 (TSST-1)-producing Staphylococcus aureus MN8 was grown in dialyzed beef heart infusion broth, or dialyzed beef heart infusion broth supplemented with 5% human blood or with 5% human semen, in the presence and absence of Today contraceptive sponges. Early growth of the organism was inhibited by the presence of the sponges in aerobic, static aerobic, and anaerobic cultures. In aerobic cultures that contained the sponge, minimal TSST-1 was detected by immunodiffusion assay, whereas in control cultures that did not contain the sponge, extensive toxin production was seen. In static and anaerobic cultures, the presence of the contraceptive sponge resulted in toxin levels less than or equal to the low levels seen in control cultures. These results suggest that Today contraceptive sponges may inhibit TSST-1 production by S aureus.

Resin-bonded prostheses: microleakage and luting agent thickness of etched and cast-meshwork retainers

The purpose of this study was to compare in vitro marginal leakage, metal surface features, and luting resin film thickness between electrolytically etched and cast mesh resin-bonded retainer designs. The rate of microleakage along an etched metal-composite interface appears to be considerably slower than along a cast mesh-composite interface. Significant differences in surface area between these two retention systems, especially at the margin, is thought to be primarily responsible. Whether such a microleakage difference will be meaningful in terms of clinical longevity remains a matter for further study. Luting resin thickness was found to be significantly less for etched retainers. This may be due to characteristics of framework adaptation to the teeth under the conditions of this investigation.