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PubMed2003

The antisuicidal and mortality-reducing effect of lithium prophylaxis: consequences for guidelines in clinical psychiatry.

The suicide-related mortality among patients with affective disorders is approximately 30 times higher, and overall mortality 2 to 3 times higher, than suicide-related mortality in the general population. Lithium has demonstrated possibly specific antisuicidal effects apart from its prophylactic efficacy: it significantly reduces the high excess mortality of patients with affective disorders. To date, suicide-prevention effects have not been shown for antidepressant or anticonvulsant long-term treatment. Clozapine appears to reduce the suicide rate in schizophrenia patients. Against this background, guidelines and algorithms for selecting an appropriate prophylactic strategy for affective disorders should consider the presence of suicidality in patient history. Appropriate lithium prophylaxis prevents approximately 250 suicides yearly in Germany, although lithium salts are infrequently prescribed within the National Health Scheme (specifically, to 0.06% of the population). Rational treatment strategies most likely would demand that prescription rates be about 10 times higher.

Algorithms↗
PubMed2003

Lithium augmentation therapy in refractory depression: clinical evidence and neurobiological mechanisms.

OBJECTIVE: This systematic review examines the evidence and discusses the clinical relevance of lithium augmentation as a treatment strategy for refractory major depressive episodes. It also examines hypotheses on the mode of action of lithium augmentation, with a focus on serotonin (5-HT) and neuroendocrine systems, and proposes recommendations for future research. METHOD: We searched the Medline computer database and the Cochrane Library for relevant original studies published in English from January 1966 to February 2003. The key words were as follows: lithium, augmentation strategies, lithium augmentation, major depression, refractory depression, treatment-resistant depression, neuroendocrinology, and serotonin. RESULTS: Of 27 prospective clinical studies published since 1981, 10 were double-blind, placebo-controlled trials, 4 were randomized comparator trials, and 13 were open-label trials. Five of 9 acute-phase placebo-controlled trials demonstrated that lithium augmentation had substantial efficacy. In the acute-treatment trials, the average response rate in the lithium group was 45%, and in the placebo group, 18% (P < 0.001). One placebo-controlled trial showed the efficacy of lithium augmentation in the continuation-phase treatment. Summarizing the open and controlled data, approximately 50% of patients responded to lithium augmentation within 2 to 6 weeks. Animal studies offer robust evidence that lithium augmentation increases 5-HT neurotransmission, possibly by a synergistic action of lithium and the antidepressant on brain 5-HT pathways. CONCLUSIONS: Augmentation of antidepressants with lithium is the best-documented augmentation therapy in the treatment of refractory depression. Emerging data from animal studies suggest that the 5-HTergic system is involved in the augmentatory effect of lithium.

Animals↗
PubMed2003

The cortisol awakening response in bipolar illness: a pilot study.

OBJECTIVE: A growing body of data suggests that a significantly enhanced salivary cortisol response to waking may indicate an enduring tendency to abnormal cortisol regulation. Our objective was to apply the response test to a population already known to have long-term hypothalamo-pituitary-adrenocortical (HPA) axis dysregulation. We hypothesized that the free cortisol response to waking, believed to be genetically influenced, would be elevated in a significant percentage of cases, regardless of the afternoon Dexamethasone Suppression Test (DST) value. METHOD: Using the free cortisol response to waking and the short daytime profile, we tested 18 clinically stable, lithium-responsive subjects from our long-term naturalistic follow-up of monthly DSTs. These tests include salivary testing every 15 minutes during the first hour of waking, followed by samples taken at 3:00 PM and 8:00 PM. RESULTS: While clinically stable on lithium prophylaxis, patients with bipolar disorder (BD) showed a significantly enhanced salivary cortisol response to waking, compared with control subjects (P < 0.03). Cortisol levels 30 minutes after waking significantly exceeded those in the large normative data provided in the literature (P < 0.001). CONCLUSIONS: Our observations support the hypothesis that the free cortisol response to waking can reflect relatively enduring HPA dysregulation, even when lithium-responsive BD patients are clinically well and their DSTs are normal. Because the test is easy to administer, the free cortisol response to waking may hold promise as a marker in studies of high-risk families predisposed to, or at risk for, mood disorders.

Adult↗
PubMed2003

Lifetime prediction of all-ceramic bridges by computational methods.

There has been limited use of ceramic materials for all-ceramic posterior bridges. Major reasons are the low strength, the strength scatter, and the time-dependent strength decrease of ceramics due to slow crack growth. The objective of this study was to predict the long-term failure probability and loading capability of all-ceramic bridges (Empress 1, Empress 2, In-Ceram Alumina, and ZrO(2)) by computational techniques. The lifetimes of different bridge model designs were predicted by means of the NASA post-processor CARES. Bridges made of zirconia showed a very high mechanical long-term reliability. Empress I and InCeram Alumina seem to be insufficient as posterior bridge materials based on this prediction. The lifetime of the all-ceramic bridges can be significantly increased by improving the design in the connector area. We conclude that computational techniques can help to judge a ceramic material and a specific ceramic bridge design with respect to mechanical reliability before clinical use.

Aluminum Oxide↗
PubMed2003

Effect of surface roughness on flexural strength of veneer ceramics.

The strength of ceramic restorations depends on the occlusal surface roughness of the veneering porcelain, which is influenced by the final preparation. The hypothesis of the study was that roughnesses below a critical microscopic defect size--based only on fracture mechanics considerations--also affect flexural strength. The bending failure stress was evaluated on standard specimens of 4 veneer ceramics with 4 different surfaces of defined roughnesses, respectively. A linear correlation was found between roughness and failure stress. A "roughness-free" failure stress value was predicted for each tested material. This theoretical value can represent the "true" strength of the respective ceramic material. We conclude from our results that the final preparation of a ceramic restoration is critical to the strength of the material, and that ceramic veneering materials can be compared more objectively with respect to their strength by means of roughness-free strength values.

Air Abrasion, Dental↗
PubMed2006

Fracture surface analysis of clinically failed fixed partial dentures.

Ceramic systems have limited long-term fracture resistance, especially when they are used in posterior areas or for fixed partial dentures. The objective of this study was to determine the site of crack initiation and the causes of fracture of clinically failed ceramic fixed partial dentures. Six Empress 2 lithia-disilicate (Li(2)O x 2SiO(2))-based veneered bridges and 7 experimental lithia-disilicate-based non-veneered ceramic bridges were retrieved and analyzed. Fractography and fracture mechanics methods were used to estimate the stresses at failure in 6 bridges (50%) whose fracture initiated from the occlusal surface of the connectors. Fracture of 1 non-veneered bridge (8%) initiated within the gingival surface of the connector. Three veneered bridges fractured within the veneer layers. Failure stresses of the all-core fixed partial dentures ranged from 107 to 161 MPa. Failure stresses of the veneered fixed partial dentures ranged from 19 to 68 MPa. We conclude that fracture initiation sites are controlled primarily by contact damage.

Compressive Strength↗
PubMed2006

Apparent interfacial fracture toughness of resin/ceramic systems.

We suggest that the apparent interfacial fracture toughness (K(A)) may be estimated by fracture mechanics and fractography. This study tested the hypothesis that the K(A) of the adhesion zone of resin/ceramic systems is affected by the ceramic microstructure. Lithia disilicate-based (Empress2-E2) and leucite-based (Empress-E1) ceramics were surface-treated with hydrofluoric acid (HF) and/or silane (S), followed by an adhesive resin. Microtensile test specimens (n = 30; area of 1 +/- 0.01 mm(2)) were indented (9.8 N) at the interface and loaded to failure in tension. We used tensile strength (sigma) and the critical crack size (c) to calculate K(A) (K(A) = Ysigmac(1/2)) (Y = 1.65). ANOVA and Weibull analyses were used for statistical analyses. Mean K(A) (MPa.m(1/2)) values were: (E1HF) 0.26 +/- 0.06; (E1S) 0.23 +/- 0.06; (E1HFS) 0.30 +/- 0.06; (E2HF) 0.31 +/- 0.06; (E2S) 0.13 +/- 0.05; and (E2HFS) 0.41 +/- 0.07. All fractures originated from indentation sites. Estimation of interfacial toughness was feasible by fracture mechanics and fractography. The K(A) for the systems tested was affected by the ceramic microstructure and surface treatment.

Acid Etching, Dental↗
PubMed2003

Spectrophotometric analysis of all-ceramic materials and their interaction with luting agents and different backgrounds.

In this study, two All-Ceramic (AC) materials--Empress 2 (EMP) (Ivoclar Vivadent AG, Schaan, Liechtenstein) and In-Ceram ALUMINA (ICA) (Vita Zahnfabrik, Bad Säckingen, Germany)--were analyzed, along with the effects of 3 luting agents-viz. Zinc Phosphate cement (ZNPO, PhospaCEM PL, Ivoclar Vivadent AG, Schaan, Liechtenstein), Glass Ionomer Cement (GIC, Ketac-Cem Radiopaque, ESPE Dental AG, Seefeld, Germany), and Compolute (COMP, ESPE Dental AG, Seefeld, Germany)--on the final color, using the CIELab system. Color differences (DeltaL, Deltaa, Deltab, and DeltaE) were calculated for samples with luting agents and for samples without luting agents with standard white and black backgrounds, with the use of a spectrophotometer, Luci 100 (Dr. Lange, Berlin, Germany). One-way ANOVA for DeltaL, Deltaa, Deltab, and DeltaE within both the AC systems, with and without luting agents, showed significant contributions of the background (p < 0.05). EMP was seen to be more translucent than ICA. Darker ceramics showed less color variation. Luting agents altered the final color of the restoration. ZNPO was least translucent, followed by GIC and COMP. Marginal increases in thicknesses of ICA samples (0.4 mm) do not show a statistically significant color difference. No method exists to predict the outcome of an AC restoration based on consideration of the luting agent and the background color.

Analysis of Variance↗
PubMed1994

A comparative study of the shear bond strengths of four different crystal growth solutions.

Previously, solutions based on polyacrylic acid have been found to initiate crystal growth on the enamel surface. Such crystals have been proposed as being suitable for the attachment of orthodontic brackets via a conventional composite interface, the advantages being improved clean-up characteristics and reduced damage to the enamel. In order to try and improve the reliability of the technique this base solution has been modified by the authors, by the addition of various ionic salts. The strength of the resultant bond was assessed for the base solution of 50 per cent polyacrylic acid and concentrated sulphuric, and for three more solutions modified by the addition of the sulphates of lithium, magnesium, and potassium, respectively. A standard acid/etch method of bracket attachment was also included for the purposes of comparison. The bond strength of each material was assessed by shear testing, performed on human extracted premolar teeth to a standard method. As might have been expected the acid/etch system proved to be the strongest method of bonding brackets. Amongst the crystal solutions, the addition of lithium sulphate provided the highest mean shear strength at 80 per cent of that for acid etch. Therefore, this latter solution provides the most potential for development in the future.

Acid Etching, Dental↗
PubMed1995

Crystal bonding--an adhesive system with a future?

The primary objective of this investigation was to evaluate the crystal bonding technique and to: (1) study the effect on crystal size, coverage, and morphology of altering the concentration of lithium sulphate in a crystal growth solution; (2) investigate the potential for reattachment of brackets, following the use of the crystal growth technique; (3) assess the deterioration of the crystal growth conditioning solution with time; (4) investigate the influence of polyacrylic acid enamel pretreatment on the bond strength subsequently achieved with the crystal growth technique; and (5) confirm that the use of crystal growth solutions to attach orthodontic brackets, results in minimal enamel surface change on debond when compared to the acid etch technique. The results of the study suggest that altering the lithium sulphate concentration of the crystal growth solution results in little alteration in the size, morphology, and coverage of crystal produced. The crystal growth technique allows reattachment of orthodontic brackets with no obvious deterioration in bond strength and the crystal growth solution shows little deterioration in performance after storage for 2 years. However, the hope that the use of the crystal growth technique might be a routine and valid alternative to the acid etch technique could not be confirmed.

Acid Etching, Dental↗
PubMed1997

Generalisability of results from randomised drug trials. A trial on antimanic treatment.

BACKGROUND: Exemplified by a randomised trial on antimanic treatment, this paper addresses the question of whether selection of patients for drug trials may limit the applicability of study results from the randomised patients to a wider population. METHOD: During two-year period, all consecutively admitted patients from a defined catchment area were screened for inclusion criteria concerning age, diagnosis and severity of illness. The subsequently excluded subgroups of patients were compared with the randomised patients by multivariate data analysis. RESULTS: One hundred and sixty-four patients met the inclusion criteria. However, after exclusion for various reasons, only 27 (17%) patients remained for randomisation. The randomised patients and the excluded patients differed substantially. CONCLUSIONS: The generalisability of trial results is limited. Reports of randomised drug trials should carefully describe the screening procedure for inclusion and, when possible, present relevant comparisons-between the randomised patients and the various subgroups of excluded patients.

Adolescent↗