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PubMedDate not supplied

Degree of conversion and surface hardness of resin cement cured with different curing units.

OBJECTIVE: The aim of this study was to evaluate the degree of conversion and Vickers surface hardness of resin cement under a simulated ceramic restoration with 3 different curing units: a conventional halogen unit, a high-intensity halogen unit, and a light-emitting diode system. METHODS AND MATERIALS: A conventional halogen curing unit (Hilux 550) (40 s), a high-intensity halogen curing unit used in conventional and ramp mode (Optilux 501) (10 s and 20 s, respectively), and a light-emitting diode system (Elipar FreeLight) (20 s, 40 s) were used in this study. The dual-curing resin cement (Variolink II) was cured under a simulated ceramic restoration (diameter 5 mm, height 2 mm), and the degree of conversion and Vickers surface hardness were measured. For degree of conversion measurement, 10 specimens were prepared for each group. The absorbance peaks were recorded using the diffuse-reflection mode of Fourier transformation infrared spectroscopy. For Vickers surface hardness measurement, 10 specimens were prepared for each group. A load of 200 N was applied for 15 seconds, and 3 evaluations of each of the samples were performed. RESULTS: Degree of conversion achieved with Optilux 501 (20 s) was significantly higher than those of Hilux, Optilux 501 (10 s), Elipar FreeLight (20 s), and Elipar FreeLight (40 s). For Vickers surface hardness measurement, Optilux 501 (20 s) produced the highest surface hardness value. No significant differences were found among the Hilux, Optilux 501 (10 s), Elipar FreeLight (20 s), and Elipar FreeLight (40 s). CONCLUSION: The high-intensity halogen curing unit used in ramp mode (20 s) produced harder resin cement surfaces than did the conventional halogen curing unit, high-intensity halogen curing unit used in conventional mode (10 s) and light-emitting diode system (20 s, 40 s), when cured through a simulated ceramic restoration.

Dental Porcelain↗
PubMed2005

Issues in treatment-resistant depression.

Major depressive disorder is a debilitating disease that imposes significant social and economic burdens not only on patients but also on society. Although various treatment options are available, treatment-resistant depression is common. Determining the exact prevalence of treatment-resistant depression is difficult because definitions vary, as do definitions of antidepressant response. Operational definitions of antidepressant response, nonresponse, partial response, and remission will be discussed in this article. Pharmacotherapy options for patients with treatment-resistant depression include augmentation, combination, and switching therapies; however, data from controlled clinical trials supporting these therapies are limited. Electroconvulsive therapy and psychotherapy offer additional treatment strategies. New nonpharmacologic therapies are under investigation. Remission is the goal of treatment.

Anticonvulsants↗
PubMed2005

Comparison of the bond strength of stainless steel orthodontic brackets bonded to crown porcelains.

BACKGROUND: The bond strengths and mode of failure of stainless steel orthodontic brackets bonded to the newer all-ceramic crown systems has not been fully investigated. OBJECTIVES: To compare the shear-peel bond strengths and modes of failure of stainless steel Begg orthodontic brackets bonded to all-ceramic crown systems (Finesse, Empress II) and a conventional feldsphatic crown porcelain (Vita Omega 900). METHODS: Fifteen flat-surface discs of three crown porcelains (Finesse, Vita Omega 900, Empress II) were made and mounted in acrylic moulds. The discs were pumiced, etched with phosphoric acid, primed with silane, and a flat stainless steel Begg bracket bonded to each disc with a chemical cure composite resin (Unite Bond). The discs were stored for one week in water and debonded with a sheer-peel load in an Instron uniaxial testing system with a crosshead speed of 0.5 mm/min. The composite remnants on the ceramic surfaces were classified using the Adhesive Remnant Index (ARI). RESULTS: The bond strength of Finesse (15.03 +/- 1.90 MPa) was significantly greater (p < 0.001) than Vita Omega 900 11.51 +/- 2.35 MPa) and Empress II (11.12 +/- 1.78 MPa). There were no significant differences among the ARI scores. The mode of failure was a mixture of adhesive and cohesive failure. CONCLUSION: The results indicate that the bond strengths of stainless steel orthodontic brackets bonded to Finesse and Empress II porcelains are clinically acceptable.

Acid Etching, Dental↗
PubMedDate not supplied

Curing efficiency of a photo- and dual-cured resin cement polymerized through 2 ceramics and a resin composite.

PURPOSE: The influence of the curing mode (dual vs light) and of the photopolymerization through ceramic or resin composite on the degree of remaining carbon bonds was investigated via infrared spectroscopic analysis for 1 resin cement (Calibra, Caulk/Dentsply). MATERIALS AND METHODS: The 0.5-mm cement layer was photopolymerized for 40 s through the 2-mm-thick ceramic Empress 2 (Ivoclar) and Vitadur Alpha (Vident) and the laboratory-processed resin composite Sinfony (3M/ESPE). RESULTS: The dual-cured system polymerized better than the light mode. Photopolymerization of the resin cement through the translucent materials reduced its curing efficiency in both curing modes. The resin composite induced a more negative effect than the 2 ceramics tested. CONCLUSION: The curing mode and photopolymerization of dual-cured resin cements through esthetic restorative materials affects the degree of remaining double carbon bonds.

Aluminum Silicates↗
PubMed2006

[Study on the expansion properties of homemade fast investment material for the IPS-Empress2 castable ceramic].

IPS-Empress2 is a successful all-ceramic restoration system. To lower its cost, and promote its application, a kind of homemade fast investment material has been developed. The aim of this study was to evaluate the expansion properties of this investment material. The setting expansion, thermal expansion and total expansion of the homemade fast investment material were tested. The same properties of the IPS special fast investment material were also tested as control. Then the SPSS statistics software was used to evaluate the differences between the homemade material and the special material. The results show that the setting expansion rate, thermal expansion rate and total expansion rate of the special investment material for IPS-Empress2 are 0.858%, 1.11% and 1.17% respectively, while the same parameters of the homemade investment material are 0.798%, 1.09% and 1.16% respectively. There is no statistically significant difference in these expansion properties between the two investment materials. In conclusion, the expansion properties of homemade fast investment material are comparable to those of the special fast investment material, so it can compensate for the cast contraction of IPS-Empress2 castable ceramic precisely.

Aluminum Silicates↗
PubMed2006

Survival rates of IPS empress 2 all-ceramic crowns and fixed partial dentures: results of a 5-year prospective clinical study.

OBJECTIVE: The aim of this prospective clinical study was to evaluate the survival rates of IPS Empress 2 (Ivoclar Vivadent) all-ceramic crowns and fixed partial dentures (FPDs) after an observation period of up to 5 years. METHOD AND MATERIALS: Forty-three patients (19 women and 24 men) were included in this study. The patients were treated with a total of 58 adhesive bonded IPS Empress 2 restorations. A total of 27 single crowns were placed on molars and premolars, and 31 three-unit FPDs were placed in the anterior and premolar regions. Clinical follow-up examinations took place at 6, 12, 24, 36, 48, and 60 months after insertion. Statistical analysis of the data was calculated using the Kaplan-Meier method. RESULTS: Results of the 50-month analysis (interquartile range, 33 to 61 months) showed that the survival rate was 100% for crowns and 70% for FPDs. Six failures that occurred exclusively in the three-unit FPDs were observed. Framework fractures were recorded in three FPD units where the connector dimensions did not meet the manufacturer specifications. Only one FPD exhibited an irreparable partial veneer fracture, and 2 FPDs showed evidence of biologic failures. The accuracy of fit and esthetic parameters were clinically satisfactory for crowns and FPDs. CONCLUSION: The results of this 5-year clinical evaluation suggest that IPS Empress 2 ceramic is an appropriate material for the fabrication of single crowns. Because of the reduced survival rates, strict conditions should be considered before the use of IPS Empress 2 material for the fabrication of three-unit FPDs.

Adult↗
PubMed2006

Fracture strength of teeth restored with all-ceramic posts and cores.

OBJECTIVE: The purpose of this in vitro investigation was to evaluate the fracture strength of endodontically treated teeth restored with different all-ceramic posts and cores. METHOD AND MATERIALS: Seventy-two endodontically treated human maxillary central incisors were divided into 3 groups with 24 teeth each and restored with 1 of the following methods: prefabricated zirconia ceramic posts and resin composite buildups; zirconia ceramic posts and copy-milled alumina ceramic cores (2-piece technique), or copy-milled all-ceramic posts and cores made from a zirconia-reinforced glass-infiltrated alumina ceramic (1-piece technique). Each group was divided into 3 subgroups of 8 samples each, consisting of teeth that did not receive crown restorations and were stored for 60 days, teeth restored with all-ceramic crowns and stored for 60 days, and teeth restored with all-ceramic crowns and subjected to 1.2 million loading cycles with 30 N in a chewing simulator. RESULTS: The mean fracture strengths ranged from 205 to 522 N. Prefabricated zirconia posts and resin composite buildups showed a statistically significantly lower fracture strength after chewing simulation than teeth restored with prefabricated zirconia posts and alumina ceramic cores. CONCLUSION: All-ceramic posts and cores made with the 2-piece technique showed promising fracture strengths under the tested conditions.

Acrylic Resins↗
PubMed2006

An in vitro investigation into the surface roughness of 2 glazed, unglazed, and refinished ceramic materials.

OBJECTIVE: It is common practice for clinicians to adjust the porcelain surfaces of dental prostheses. The change in surface roughness after different surface finishing techniques has attracted the attention of prosthodontists. The present study was undertaken to investigate the average surface roughness of 2 dental ceramics: IPS Empress 2 (layering glass-ceramic, Ivoclar Vivadent) and In-Ceram/Vitadur Alpha (Vita), either glazed, unglazed, or refinished using different techniques. METHOD AND MATERIALS: Disks of 6-mm diameter and 2-mm thickness were prepared from IPS Empress 2 and In-Ceram Alumina/Vitadur Alpha ceramics. Specimens were finished for 1 minute to the various stages provided in the sequence of instruments in the Shofu porcelain veneer kit. The average roughness measurements were taken from each specimen with a surface roughness tester. RESULTS: Significant differences in surface roughness were observed between the ceramics and among the finishing techniques used for both IPS Empress 2 and In-Ceram/Vitadur Alpha. It was found that unglazed IPS Empress 2 is rougher than unglazed In-Ceram/Vitadur Alpha. CONCLUSION: Regardless of the type of ceramic or pretreatment, any adjusted ceramic restoration should be reglazed or subjected to a finishing sequence that is followed through to a final stage of polishing with diamond paste.

Aluminum Oxide↗
PubMedDate not supplied

[New therapeutic options in Alzheimer's disease].

INTRODUCTION: At present, cholinesterase inhibitors constitute the basis for therapy of Alzheimer's disease (AD); these drugs were rationally introduced given the loss of central cholinergic neurotransmission, even though there are many other systems affected in AD, including glutamatergic pathway. DEVELOPMENT: In addition to the loss of central cholinergic neurotransmission, biochemical evidence suggests glutamatergic dysfunction in AD and thus, therapeutic strategies directed at the glutamatergic system may be useful. These drugs include milacemide, cicloserine and ampakines (positive modulation) and memantine (negative modulation). Lithium seems to be a promising agent in AD, although the mechanism of action is poorly understood. Finally anti-inflammatory agents may be another therapeutic approach to AD. CONCLUSION: In addition to drugs acting on the cholinergic system, a large number of drugs with different mechanism could be used for the treatment and prevention of AD.

Acetamides↗
PubMed2006

Evaluation of bond strength of metal brackets by a resin to ceramic surfaces.

OBJECTIVE: The purpose of this study was to evaluate the bond strength of three different ceramic brands with two different ceramic surfaces (glazed and deglazed), with and without silane application. METHODOLOGY: Using the three different ceramics (Empress 2, Finesse, and Ceramco II), two metallic brackets were bonded to each sample, one with the adhesive system and the other one with a silane application. The samples were thermocycled, and then the debonding tests were performed with the Instron Universal Testing Machine. All the results were statistically analyzed with a three-way analysis of variance (ANOVA) test. RESULTS: The three-way ANOVA (brand, ceramic surface, with/without silane) indicated significant differences among them (p < 0.05). ANOVA showed that the greatest bond strength value (megapascals, MPa) was for Empress 2 deglazed with the silane application (8.873 MPa), followed by Finesse glazed with the silane application (7.072 MPa). CONCLUSION: The ceramic surface has a direct effect on adhesion. Therefore, Empress 2 deglazed achieved the greatest value in bond strength. To achieve the ideal values of 6-10 MPa, applying silane to the ceramic surface before bonding the brackets is recommended, even though silane can damage the ceramic surface.

Dental Bonding↗
PubMedDate not supplied

[Preclinical toxicological study of the new enterosorbent noolit].

The safety of the new enterosorbent noolit has been evaluated within the framework of its preclinical characterization. Single introduction of noolit to rats and mice (females and males) in maximum doses for intragastric administration (5.0 - 20.0 g/kg) does not lead to the loss of experimental animals. Single administration of large doses (5 - 40 times the effective dose) can reduce the growth of the total body weight and lead to the development of nonlethal pathological changes of hemopoietic organs, which is manifested by a weak regenerative anemia (5% of cases); neutrophile, eosinophile, and basophile leukocytosis (3% of cases); and a decrease in the glucose level in blood serum. In chronic experiments on rabbits, the administration of noolit for 3 months in a dose of 0.5 and 2.0 g/kg (2 and 8 times that recommended for humans) did not reveal any toxic action on the functional and morphological state of the main systems and organs (blood, liver, kidneys, lungs, heart, gastrointestinal tract, sex organs, etc.).

Aluminum Oxide↗
PubMed2006

[Treatment of acute lithium intoxication with high-flux haemodialysis membranes].

Lithium carbonate is commonly prescribed for the treatment of bipolar (manic-depressive) disorders. However, because of its narrow therapeutic index an excessive elevation of serum lithium concentration, either during chronic maintenance therapy or after an acute overdose, can result in serious toxicity. In addition to supportive care, the established treatment of severe lithium toxicity is haemodialysis. Conventional haemodialysis can reduce serum lithium rapidly, but post-dialysis rebound elevations with recurrent toxicity have been documented in old publications. High-flux membranes should be capable of removing more lithium per hour of haemodialysis, but published values are not available. We report here three patients with acute lithium intoxication who were treated successfully with bicarbonate and high-flux haemodialysis membranes. Our patients presented with a severe degree of intoxication, based on the amount of drug ingested, the initial serum lithium level, the severity of neurologic symptoms and systemic manifestations. Two patients developed acute renal failure probably as a result of volume depletion since it was rapidly reversible by haemodialysis and infusion therapy. In addition, consecutive haemodialysis sessions and improvement of renal function allowed a rapid decrease in serum lithium levels without haemodynamic instability or rebound elevations in lithium concentration. The effectiveness of the procedure in these cases can be attributed to the use of bicarbonate dialysate and high-efficiency dialysers. This is the first report describing the effect of high-efficiency dialysers on lithium pharmacokinetic. Using this technique the elimination rate of lithium was found to be greater than previously reported with haemodialysis.

Acute Disease↗
PubMed2006

Using lithium.

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Humans↗
PubMed2006

Use of lithium in the treatment of thyrotoxicosis.

OBJECTIVES: To evaluate the efficacy and safety of lithium in the treatment of thyrotoxicosis, and to study the dose and serum levels at which therapeutic response occurs. DESIGN: Retrospective study. SETTING: Thyroid clinic of a regional hospital in Hong Kong. PATIENTS: Thirteen patients with thyrotoxicosis pending therapy with radioiodine or surgery, in whom thionamides were contra-indicated due to adverse reactions or failure of treatment. MAIN OUTCOME MEASURES: Free thyroxine levels, time to euthyroidism, and side-effects of lithium. RESULTS: A satisfactory response, defined as a fall by 40% or more in free thyroxine levels and clinical improvement, was achieved in eight patients within 1 to 2 weeks of lithium therapy. In four others, response occurred in 3 to 5 weeks. Response was slow and inadequate in one patient due to 'escape'. The median dosage of lithium was 750 mg daily, with a range of 500 to 1500 mg daily. The median serum lithium level was 0.63 mmol/L. Lithium toxicity was observed in one patient. CONCLUSIONS: A relatively low dose of lithium offers a safe and effective alternative means of controlling thyrotoxicosis in patients who cannot tolerate or do not respond to thionamides.

Adolescent↗
PubMed2006

Treatment of rapid-cycling bipolar disorder.

Rapid-cycling bipolar disorder is associated with poorer treatment response, poorer long-term prognosis, and probable higher suicide risk than bipolar disorder without rapid cycling. Patients with rapid cycling tend to experience more depressive than manic episodes, and the depressive episodes tend to be more refractory in nature compared with those in patients without rapid cycling. Results from studies of rapid cycling show that antidepressant use is most likely associated with the onset or worsening of rapid cycling. Controversy also exists as to whether rapid cycling is a transitory phenomenon in the course of bipolar illness or a more chronic condition better characterized as a subtype of the illness. Results from the first 500 patients with bipolar I or bipolar II disorder enrolled in the Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD) study found an association between rapid cycling and depression and younger age at illness onset. Treatment involves a 3-part pathway to manage rapid cycling that includes reducing or stopping any possible cycle-promoting agents, adding or optimizing mood stabilizers, and using experimental or putative treatments for persistent rapid cycling after more traditional treatments have failed. Effective treatments for some patients with rapid-cycling bipolar disorder currently include lithium, divalproex, lamotrigine, carbamazepine, atypical antipsychotics, and psychosocial therapy.

Age of Onset↗
PubMed2006

Lithium as an adjunct to radioiodine therapy in Graves' disease for prolonging the intrathyroidal effective half-life of radioiodine. Useful or not?

AIM: Evaluation of intrathyroidal kinetics of radioiodine with and without lithium as adjunct with respect to the increase in radiation dose delivered to the thyroid. PATIENTS, METHODS: 267 patients in three groups were included in the study. Group I with 227 patients served as control group, Group II with 21 patients and Group III with 19 patients were distinguished by an intrathyroidal half-life of radioiodine below 3.5 days in the diagnostic test. Patients in Group III received 885 mg lithium carbonate a day for 2 weeks as adjunct to radioiodine therapy. Both diagnostic and therapeutic radioiodine kinetics were followed up by at least 10 uptake measurements within a minimum of 48 h. Kinetics of radioiodine were defined mathematically as balance of the thyroidal iodine intake and excretion by a two-compartment model. RESULTS: Under therapy the maximum uptake of radioiodine was reduced by nearly 10% in all groups, in Group I, the effective half-life as well as the product of maximum uptake x effective half-life as an equivalent of radiation dose independent of thyroid volume was lowered in the same magnitude. In Group II, the energy-dose equivalent remained constant under therapy. With adjunct lithium in Group III, the effective half-life was prolonged significantly by factor 1.61 +/- 0.49 and the volume-independent energy-dose equivalent by factor 1.39 +/- 0.37. No severe side effects of lithium were observed. CONCLUSION: Using lithium as adjunct to radioiodine therapy increases the radiation dose delivered to the thyroid by 39% on average and nearly 30% of radioiodine activity can be saved in these patients. Lithium is recommended in patients with very short effective half-life in the diagnostic test in order to reduce the activity required and whole-body radiation dose.

Adolescent↗