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PubMed2006

[Influence of different convergence angles on the retention of cast metal post and core].

Fifty-four simulated tooth roots made of polymethacrylate (PMMA) were divided into six groups according to the root canal convergence angles of 0 degrees, 3.93 degrees, 5.71 degrees, 7.48 degrees, 11.31 degrees, 14.71 degrees. Cast post and cores were manufactured and cemented with Zinc phosphate cement (ZP). The retention capacities of the posts were tested. The bonding strength of ZP at different convergence angles were tested with some casted wafers, and linear regression was made. So the effect of interlocking and the proportion could be calculated. With these results, we made some curvilinear regressions. The results showed that the retention of cast post declined and the bonding strength of ZP fell with the increase of convergence angles. There were significant differences in the bonding strength and retention among groups, P<0.05. The experiment indicates that the dentists should reduce the convergence angles of posts as much as possible to obtain greater retention.

Cementation↗
PubMedDate not supplied

Comparison of the retentive characteristics of cobalt-chromium and commercially pure titanium clasps using a novel method.

This study aimed to compare the retentive forces of cast cobalt-chromium (Co-Cr) and commercially pure titanium (cpTi) clasps. A clasp assembly comprising a pair of symmetrical clasps was made to fit the opposite halves of a hardened stainless-steel sphere. This twin clasp was designed to counterbalance the tipping forces when the clasp assembly was drawn from the sphere. A total of 120 clasp assemblies were fabricated in cast Co-Cr and cpTi and placed at undercut depths of 0.25 mm, 0.50 mm, and 0.75 mm (n = 20 for each). For Co-Cr clasps, the retentive forces at these undercuts depths were 2.34 +/- 0.23 N, 4.65 +/- 0.35 N, and 7.56 +/- 0.50 N, respectively. The corresponding retentive forces for cpTi clasps were 1.24 +/- 0.13 N, 2.34 +/- 0.23 N, and 3.70 +/- 0.27 N. The retentive force of cpTi clasps was approximately half that of Co-Cr clasps for the same undercut depth.

Chromium Alloys↗
PubMed1991

[Postoperative urinary retention].

Postoperative retention of urine (PU) is a common complication which may occur after any surgical intervention. It may affect both sexes in all age groups and result in considerable morbidity. The frequency depends upon the type of operation and its duration but statements in the literature vary greatly on account of inaccurate and varying definitions and uncertain diagnostic criteria. Intervention in the true pelvis results in the highest frequencies of postoperative urinary retention. The method of anesthesia is of lesser significance. Spinal anesthesia and epidural morphine constitute, however, a particular risk for the development of postoperative retention of urine. The pathological physiology is complex and includes: 1) disturbance of the balance between the sympathetic/parasympathetic influence on bladder and urethral function, 2) drugs which inhibit the miction reflex, 3) anaesthesia and sedation which cloud the awareness of bladder filling, 4) rapid filling of the bladder with subsequent overdistension, 5) lesion of the nerve fibres to the lower urinary tract, 6) mechanical obstruction and 7) difficult positions and/or situations for miction. Preoperative information about difficulty in emptying the bladder constitutes a predisposing factor and may require preoperative elucidation and treatment. Postoperative retention of urine may be countered by informative and practical measures and restriction of fluid intake. In selected cases, prophylactic treatment with alpha-blockers and prostaglandin may reduce the frequency. Therapeutically, oral parasympathomimetica do not appear to be effective while alpha-blockers may be employed. In cases where catheter treatment is employed and which is anticipated to be required for more than 48 hours, suprapubic drainage is recommended as this results in fewer cases of urinary infection than transurethral indwelling catheters.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1991

Postoperative urinary retention associated with total hip and total knee arthroplasties.

Urinary retention following total hip and knee arthroplasty is a common problem frequently necessitating either prolonged urethral catheter drainage or intermittent catheterization. The direct relationship of urinary tract instrumentations, procedures, and infections to deep sepsis in total hip replacements is well documented. Pharmacologic therapy to stimulate voiding or augment bladder emptying is thus theoretically preferable to the use of catheterization. Prasozin hydrochloride, an alpha blocker, relaxes the smooth musculature of the posterior urethra and prostrate and has been used to treat urinary obstruction secondary to benign prostatic hypertrophy. A prospective study in 60 male patients showed a statistically significant decrease in postoperative urinary retention with the perioperative administration of prazosin (p less than 0.01). A higher incidence of urinary tract infection was seen in patients who developed urinary retention (3% versus 20%) (p less than 0.01). Uroflowmetry parameters were not predictive of the patient at risk for retention and were unaltered with the administration of prazosin. Prazosin can be an effective adjunct in the prophylaxis of postoperative urinary tract infections and may decrease the potential risk for total joint sepsis.

Aged↗
PubMed1990

[Retention of adhesive bridges].

Since the development of adhesive bridges in the early seventies, the retention and therefore the durability of these bridges has been tremendously improved. To ensure an adequate retention over a number of years different factors have to be considered. Conditioning of the non-precious metal by silanisation, careful acid etching of the enamel and the use of the appropriate composite resin (Panavia Ex) are of prime importance. Furthermore, the meticulous preparation with enough interproximal embrace, occlusal rets, interocclusal clearance of 0.4 mm and cingulum stops is equally important. Care should be taken not to remove all the enamel in the cervical region in preparing a mini chamfer. Including more teeth in the design does not necessarily lead to an improved retention. Teeth with a different mobility should not be included in the same bridge. Besides the material and technical aspects, the whole clinical procedure needs much attention. Only an exact impression, a precise model and a reliable casting technique will provide a metal frame with an optimal marginal adaptation and a close fit. The retention does not depend on one single factor but on the precision of all the necessary clinical steps and on a well-defined selection of the material. In this way a five-year survival rate of close to 90% can be obtained.

Acid Etching, Dental↗
PubMedDate not supplied

[Experimental study of removable partial denture retention].

This article describes a series of laboratory experiences about the retentive action of different designs of free end removable partial dentures. It reaffirm the classic concept of the better efficiency of the gingival -occlusal arm clasp than the gingival-occlusal ones, the efficiency and benefits of the rough clasp and the important retention of the posterior action clasp. We find also that the classic concepts of direct and indirect retention can be reformulated, in attention than the odem retainers, such as derived from DPI conception, develops an integral concept of retention and a rational system of fixing derived of the retainer design and the abutment preparation.

Bicuspid↗
PubMed1978

[Critical considerations on the retention of individually cut attachments based on follow-up studies].

10 prostheses with individually cut attachments and 50 prosthetic appliances with parallel walled telescopic crowns were tested for their retention after a wear of between 2 and 7 1/2 years. Of the attachments only 3 cases showed good retention; in 4 it was minimal and no rentention was seen in 3 cases. Good retention was maintained in 10 telescoping prostheses, 24 had minimal and 16 no retention. Severe grades of loosening was only seen in telescoping supporting teeth where the anchor had good friction.

Adult↗
PubMedDate not supplied

The effect of tooth preparation on the retention of stainless steel crowns.

Preparations maintaining the greatest amount of buccal and lingual tooth structure were the most retentive. Cement significantly increased the retention capacity of all preparations. Mechanical retention did not contribute significantly to the separation-resistance of the stainless steel crown. Factors other than retention may be of greater importance to the clinical success of stainless steel crowns.

Cementation↗
PubMedDate not supplied

Neonatal chlordecone exposure impairs early learning and retention of active avoidance in the rat.

The effect of neonatal exposure of rats to chlordecone on the acquisition and retention of active avoidance was investigated. Pups were trained and tested on one-way (preweaning) and/or two-way (post-weaning) active avoidance tasks. Offspring of Fischer-344 rats were administered 1 mg/pup of chlordecone (SC) dissolved in DMSO on postnatal day 4. Body weights were slightly, but significantly, depressed for chlordecone-exposed males (10-11%) and females (7-8%) during preweaning development. Post-weaning body weights were also slightly depressed by the chlordecone treatment (8% for the males, 7% for the females). For pups trained (day 18) on one-way (small to large compartment) active avoidance (OWA), chlordecone treatment increased the number of trials needed to attain the acquisition criterion; the effect was most pronounced in the males. A 72-hr retention test revealed a sex-dependent effect of chlordecone on response latency during the initial test trials. Acquisition of two-way avoidance (TWA) (days 28-30) was superior in female pups relative to males; chlordecone treatment significantly reduced this sex difference in pups which had prior or no prior OWA training. Perhaps most importantly, however, following prior OWA training, vehicle control pups demonstrated a directional bias to make an avoidance response from a small to a large compartment, whereas chlordecone-treated pups executed their avoidance responses in both directions at comparable rates. Similar evidence indicative of a selective retention deficit also characterized TWA performance when a "reversal" procedure was used. A final retention (extinction) session indicated that the chlordecone-treated pups made fewer responses than vehicle-treated controls during the test trials.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1978

Retention improvement by topical application of uridine monophosphate into different brain areas.

This study aimed to demonstrate the effect of uridine monophosphate (UMP) on the consolidation of a brightness-discrimination reaction after topical application of this RNA precursor into the hippocampus, the neocortex or the mesencephalic reticular formation (MRF). Thirty minutes before the rats started their training in a Y-chamber, UMP was injected into each animal through cannula implanted into the particular brain area. When injected into hippocampus or MRF UMP exerted no influence on acquisition, but after epidural UMP injection an impairment of acquisition was observed. After intrahippocampal or epidural UMP application the retention test carried out 48 hour after training showed a significant improvement in retention performance, whereas UMP injection into MRF showed no influence on retention. Consequently, the retention-improving effect of UMP is probably not induced by activation of ascending neuronal systems.

Administration, Topical↗
PubMed1983

Exposure to the unconditioned stimulus alone: effects on retention and acquisition of conditioned suppression.

Three experiments demonstrated that repeated exposure to an electric-shock unconditioned stimulus (US) resulted in a decrement in retention of conditioned suppression evoked by a previously established excitatory conditioned stimulus (CS) and retarded subsequent acquisition of conditioned suppression to a novel CS paired with shock. Experiment 1 showed that 10 sessions of exposure to shock alone were required to produce a decrement in retention of conditioned suppression, whereas retardation in the acquisition of conditioned suppression was obtained following either 5 or 10 sessions of exposure to shock alone. Experiment 2 demonstrated that the magnitude of both the decrement in retention of conditioned suppression and the retardation in the acquisition of conditioned suppression produced by exposure to shock alone was directly related to the intensity of those shocks. Experiment 3 demonstrated that the decrement in retention of conditioned suppression produced by 10 sessions of exposure to shock alone was inversely related to the interval between the last exposure to shock and the test of the target CS. These findings are discussed in terms of associative and nonassociative accounts of the effects of US-alone procedures.

Animals↗
PubMed1995

Acute urinary retention in men: a comparison of voiding and nonvoiding patients after prostatectomy.

Multiple parameters were examined preoperatively to determine if any could predict successful voiding after prostatectomy in male patients who present in acute urinary retention due to benign prostatic hypertrophy. A total of 50 men 50 to 85 years old (mean age 69.5 years) who presented with this clinical picture was investigated with multichannel urodynamic studies, and completed the American Urological Association (AUA) symptom score for benign prostatic hypertrophy preoperatively and postoperatively. All patients underwent prostatectomy. Mean retention volume was 1,172 cc (range 500 to 2,100). Mean preoperative and postoperative AUA symptom scores were 15.5 and 5.0, respectively. At 3 months postoperatively 45 patients (90%) were able to void without catheterization. At 16.6 months 5 patients still required clean intermittent catheterization to empty the bladder. Postoperatively, there was a statistically significant improvement in AUA symptom score, opening voiding pressure and peak flow rate. The AUA symptom score was not predictive of either impending acute retention or normal voiding after prostatectomy. In our patients no preoperative parameters were statistically different between those voiding and those on clean intermittent catheterization. However, poor sensation, large retention volumes, lack of instability and no voluntary detrusor contractions were more common in the nonvoiding men.

Acute Disease↗
PubMed1994

[Acute urine retention: a rare mode of revelation of cervico-dorsal syringomyelia caused by cyproheptadine].

BACKGROUND: Syringomyelia is rare in children aged less than 10 years, and bladder dysfunction is an unlikely first manifestation. This report describes a case of repeated episodes of acute urinary retention in a young girl revealing syringomyelia and Arnold-Chiari malformation. CASE REPORT: A 2.5 year-old girl was admitted because she was suffering from acute urinary retention. Her poor appetite had been treated with cyproheptadine, a histamine type I blocking drug. Clinical investigation revealed no local cause for this bladder dysfunction except moderate spasticity of the legs. Cystography showed no vesicoureteral reflux. Because the episodes of urinary retention recurred each day, magnetic resonance imaging (MRI) was performed; this showed the typical features of syringomyelia extending from C5 to T11 plus Arnold-Chiari malformation. The cyproheptadine was discontinued and the urinary retention disappeared. CONCLUSION: Cyproheptadine may have revealed latent neurogenic bladder in this case, although urodynamic studies, performed 3 months later, detected no bladder dysfunction.

Acute Disease↗
PubMed1994

Etiology of acute urinary retention following benign anorectal surgery.

The etiology of acute urinary retention following benign anorectal surgery is unknown. We performed bedside urodynamic evaluation on nine patients who developed acute urinary retention after benign anorectal surgery. A bladder contraction was demonstrated in all patients, which suggests that the retention is due to bladder outlet obstruction and not bladder acontractility. These findings have important implications for preventing and treating acute urinary retention following anorectal surgery for benign disease.

Acute Disease↗
PubMed1993

Protein kinase C activation facilitates memory retention in rats.

We have previously found that intra-hippocampal injection of H7, a protein kinase inhibitor, impairs memory retention in rats in a one-way passive avoidance learning task. It also decreases the optical density of several hippocampal protein bands on SDS-polyacrylamide gel electrophoresis (SDS-PAGE). The present study examined whether protein kinase C (PKC) and phosphorylation of its substrate protein are involved in the memory process. The same behavioral paradigm was used. The infusion volume was 0.8 microliter each side throughout all experiments. We have microinjected phorbol ester (TPA), a specific PKC activator, into the dentate gyrus (DG) of hippocampus immediately after training. Animals were subject to the retention test 24 hr after training. Results revealed that TPA enhanced retention performance and protein phosphorylation in rats in a dose-response fashion with doses at 0.8 and 2.0 ng reaching a significant behavioral effect. The high dose of TPA also increased phosphorylation of four protein bands in the cytoplasma with molecular weight (MW) around 48 kDa, 60 kDa, 78 kDa and 116 kDa, respectively; and seven protein bands in the membrane with MW around 38 kDa, 43 kDa, 48 kDa, 80 kDa, 88 kDa, 130 kDa and 210 kDa, respectively. In different animals, we have microinjected staurosporine, a specific PKC inhibitor, into the DG of hippocampus. Results indicated that at the low dose (0.5 ng), staurosporine was without a significant effect. At the middle and high doses (2.0 and 8.0 ng), it markedly impaired retention performance.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaloids↗
PubMed1993

[The evaluation of the efficacy of auxiliary retention in the preparation of partial crowns].

An extracted maxillary human premolar was prepared for 3/4 artificial crown. Ten models of the tooth were made and different combinations of auxiliary retentive components were prepared on each model: proximal and lingual grooves, pins and boxes. For each model an artificial crown was cast cemented to it, mechanically tested for retention and graphed. Pins proved more retentive than grooves, being the latter more retentive when placed asymmetrically more than in symmetrical positioning.

Bicuspid↗
PubMed1997

Comparison of screw retention of nine abutment systems: a pilot study.

Fracturing or loosening of abutment and retaining screws is a frequent occurrence. This study was designed to evaluate the retaining ability of nine abutment systems. Abutment and retaining screws were secured to the appropriate implant using a digital torque gauge, with the abutment screws placed at 30 N-cm and the retaining screws at 10 N-cm. Removal torque was recorded three times for each sample 10 minutes after initial placement, 20 minutes after retightening, and 24 hours after retightening. There was no statistical difference in removal torque relative to time or repeated tightening. Of the nine abutment systems, three were statistically less retentive as compared with the most retentive system. The retaining screws were less retentive as compared with the abutment screws. For maximum retention the elimination of retaining screws from the restorative design and using 30 N-cm of torque for the abutment screws is suggested.

Analysis of Variance↗
PubMed1997

Prevention of urinary retention after general surgery: a controlled trial of carbachol/diazepam versus alfusozine.

BACKGROUND: Postoperative urinary retention is a common complication after surgical procedures. It can cause bladder dilatation, infection, and even sepsis. Carbachol/diazepam and alfusozine have been reported to lower the incidence of postoperative urinary retention, but no study showed the benefits of these drugs in a randomized, placebo-controlled trial. STUDY DESIGN: We used a double blind, placebo-controlled trial in which 249 patients with postoperative urinary retention were randomly assigned to receive carbachol/diazepam (n = 72), alfusozine (n = 82), or placebo (n = 95). The primary endpoint was miction within 2 hours after taking the medication. RESULTS: There was no significant difference in miction frequency after taking the medication among the three groups (p = 0.31). The miction rate was 60% for patients in the alfusozine group, 61% in the carbachol/diazepam group, and 51% in the placebo group. CONCLUSIONS: Alfusozine and carbachol/diazepam had no apparent benefit on the incidence of postoperative urinary retention.

Adrenergic alpha-Antagonists↗