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At least 1,315 records · Page 73Linked to original sources
PubMed1991

Factors influencing postoperative urinary retention in patients undergoing elective inguinal herniorrhaphy.

We retrospectively studied 295 men who had undergone herniorrhaphy under spinal or general endotracheal anesthesia to determine the incidence of postoperative urinary retention and to assess factors influencing it. The type and location of hernia had no effect on retention. In contrast, the use of general anesthesia, patient age above 53 years, and perioperative administration of more than 1,200 mL of fluid were significantly associated with an increase in retention. Our results suggest that urinary retention after herniorrhaphy may be prevented by limiting the amount of fluid given perioperatively and by using a spinal anesthetic, especially in older patients.

Adolescent↗
PubMed1976

Stimulation of rat medial or sulcal prefrontal cortex during passive avoidance learning selectively influences retention performance.

Low-level unilateral electrical stimulation was delivered during passive avoidance learning through a bipolar electrode to the prefrontal cortex of the adult albino rat. No brain stimulation was applied during a retention test measured 24 h later. Ventromedial prefrontal cortex stimulation produced retention impairment over and above that observed with chronic electrode implantation. Sulcal cortex stimulation, in contrast, actually attenuated the retention deficit produced by chronic implantation in the sulcal cortex. Stimulation of an afferent common to both prefrontal regions, the dorsomedial thalamus, resulted in retention disruption, but stimulation of another common afferent, the locus coeruleus, did not. Acquisition of the inhibitory response was not affected by stimulation of any of the above brain regions. The present results demonstrate, again, that the functional role in memory of particular brain regions can be dissected by low-level electrical stimulation. The functional separation of rat sulcal and medial cortices revealed by the effects of stimulation suggests that these prefrontal subfields subserve different functions in the information storage process.

Animals↗
PubMed1985

Delayed onset of the amnestic effect of posttraining beta-endorphin: effects of propranolol administered prior to retention testing.

Mice were trained in a 1-trial inhibitory avoidance task (0.7 mA FS) and tested for retention at 1, 3, or 6 h following training. Posttraining beta-endorphin (0.1 micrograms/mouse i.p.) administration impaired retention at 6 h, but not 1 or 3 h after training. Propranolol (0.3 mg/mouse i.p.), but not naloxone (0.1 mg/mouse i.p.) administered prior to retention testing at 1 or 3 h accelerated the onset of amnesia in mice given posttraining beta-endorphin. Neither propranolol nor naloxone affected retention when given alone. These findings suggest that the delayed onset of the amnesia produced by posttraining beta-endorphin is due to the activation of a beta-adrenergic system.

Amnesia↗
PubMed1993

Dose-response differences in the ability of ramipril to improve retention in diabetic mice.

Ramipril blocks the conversion of angiotensin I to II. The literature indicates that diabetes is often associated with mild impairment of learning and memory. The study reports the effects of ramipril on memory retention in diabetic and non-diabetic mice. Mice were made diabetic by an injection of streptozocin. After overt signs of diabetes were present, diabetic or vehicle-treated mice were partially trained on a footshock active avoidance task. Immediately after training, ramipril (0.5-1.5 mg/kg s.c.) was administered and retention was tested by continuing training one week later until mice avoided footshock on five out of six trails. The results indicate that ramipril enhanced retention of both diabetic and control mice but it required about 5 times as much ramipril in diabetic as control mice to achieve the same effect on retention. Increased sensitivity to angiotensin II may play a role in cognitive impairment in diabetes.

Angiotensin I↗
PubMed1996

Nitric oxide modulates retention of immobility in the forced swimming test in rats.

Although originally developed as a possible screen for antidepressants, the Porsolt forced swimming test has more recently been extensively used as a model for studying the involvement of the endocrine system in the acquisition and retention of behavioural responses. In previous studies we have shown that while adrenalectomised rats acquire the immobile response normally, they are unable to retain it on retest next day. In the present study we show that retention of the immobile response in the Porsolt swim test is impaired in intact rats given the nitric oxide (NO) inhibitor L-N-arginine methyl ester (L-NAME), in a dose- and time-dependent manner. At a dose of 50 mg/kg levels of immobility are similar to those in adrenalectomised animals, an effect reversed by the simultaneous administration of L-arginine (50 mg/kg). L-Arginine also reverses the behavioural effect of adrenalectomy, and L-NAME blocks the ability of dexamethasone or the kappa-selective opioid ketocyclazocine to reverse the effect of adrenalectomy on retention of the immobile response. We conclude that the kappa-opioid and glucocorticoid mediated pathways previously shown to independently facilitate retention are mediated by nitric oxide.

Animals↗
PubMed1983

The effects of distributed training on retention of operant conditioning in human infants.

Long-term retention of operant footkicking acquired in the mobile conjugate reinforcement paradigm was assessed as a function of the distribution of training time. In the first study, 3-month-old infants were trained for either one 18-min session or for two 9-min or three 6-min sessions separated by 24-hr intervals. All infants exhibited retention during a test administered immediately after training, but only those trained in a single session continued to perform the conditioned response during cued-recall tests 7 or 14 days later. Infants trained in three sessions showed no evidence of remembering the contingency even after a week. A warm-up decrement, seen in the day-to-day performance of infants in the distributed conditions, was eliminated in the second study by the interpolation of a nonreinforcement period at the outset of daily sessions. This procedure also enhanced long-term retention such that infants trained in three 6-min sessions now remembered the contingency for 14 days and did not differ from infants who had received a single 18-min session. Whether distributed training facilitates or impairs long-term retention appears to depend on the opportunity for infants to acquire a sufficient number (or kind) of effective retrieval cues during original learning.

Conditioning, Operant↗
PubMed1975

Guiding planes in clasp reciprocation and retention.

Answers to two questions were sought: Is there a proper length for a guide plane and does the relationship of the guide plane to the undercut enhance retention? The cylindrical sleeve makes it possible to measure suprabulge contours in relationship to undercuts, thus establishing the "action distance" of the retentive arm. The reciprocating distance traveled by the reciprocal part of the clasp must be equal to the action distance: action distance = reciprocation distance = length of guide plane. Three sets of ivorine teeth were used with cast clasps with a connector and with a single clasp to test this concept of intrinsic retention--"intrinsic retention" being a guide plane opposed by an undercut at 180 degrees.

Dental Abutments↗
PubMed1978

The role of saliva in retention of maxillary complete dentures.

In this study maxillary denture retention was influenced by the salivary volume between the denture base and the mucous membrane. An optimum intervening salivary volume, at which the greatest retention was developed, was also observed. It was observed from determination of electric resistance of palatal mucous membrane that inward and outward flow of intervening saliva was greater in the denture with poor retention than in the one with good retention. Moreover, when the salivary volume between the denture base and mucous membrane was optimum the salivary flow under the denture was minimum.

Adult↗
PubMed1980

The retentive and stress-distributing properties of a threaded endodontic dowel.

When the Radix Anchor apex was allowed to engage the bottom of the prepared channel, very high apical stresses were generated within the supporting structure. When the coronal flanges engaged the occlusal portion of the model, high lateral stresses occurred in the coronal portion of the channel. These stress concentrations can be avoided by installing the dowel so that only the retentive threads engage dentin. This may be accomplished by "backing off" one half turn when slight resistance to dowel threading is encountered. The Radix endodontic dowel system was more retentive than cemented dowels and less retentive than another dowel which threads into the dentin of the channel wall. The Radix Anchor was more retentive when both diameter and length of imbedment were increased simultaneously.

Crowns↗
PubMed1989

Role of the surface and volume of palatal relief chambers in retention of maxillary complete dentures.

Maxillary complete dentures were made with thickened denture bases for 10 patients. The retentive force was measured with a dynamometer. Acrylic resin was then removed with a bur from the mucosal side of the denture base, thus progressively enlarging the palatal chamber. Each enlargement was followed by measurement of the surface and volume of the chambers and the retention force of the dentures. The mean force of the denture retention diminished progressively from 57 N to 13.5 N as the chambers enlarged. An analysis of the results showed that the retention of maxillary complete dentures does not depend on the surface of the palatal chambers but is inversely proportionate to their volume.

Acrylic Resins↗
PubMed1990

Changes in retention of various telescope crown assemblies over long-term use.

An investigation was done on the effect of crown height, angle (one-half taper) and number of removals on the retention of telescope crowns. Assemblies of inner and outer crowns were constructed on master dies. Crown heights of 4 mm, 5 mm, and 6 mm were used. Cone angles of 0, 2, 4, and 6 degrees were used for each of the three heights. The inner crowns were fixed to the dies with an adhesive agent. the outer crowns were set over them and placed in a clamp. Separation forces were tested with an Instron machine (Instron Corp., Canton, Mass.). They were measured initially and after numerous 100 insertion/separation cycles up to 1000 cycles and numerous 500 insertion/separation cycles up to 10,000 cycles. The results demonstrated that the cone angle of the inner crown was more important than its height for maximum retention. Retention is rapidly lost after the cone angle exceeds 2 degrees. It was also shown that an accessory device is necessary to maintain retention capabilities after long-term use.

Analysis of Variance↗
PubMed1991

Effects of lubrication on the retention of tapered and parallel cast post and cores.

The effects of lubrication on the retention of parallel-sided and tapered cast post and cores cemented with zinc phosphate-cement (ZnPO4) and glass ionomer cements were investigated. Seventy-two maxillary canine teeth of similar size were selected for direct, parallel-sided post and core castings. The canines were sectioned at the cementoenamel junction and mounted in resin blocks. A post space was prepared to 1.5 mm (d) x 10 mm (I) with a handpiece mounted in a surveyor. The teeth were divided into four groups: ZnPO4 without lubricant, ZnPO4 with lubricant rinsed with water, ZnPO4 with lubricant removed by solvent, and ZnPO4 with solvent alone. The same four groups were made by using glass ionomer cement. Retention was tested with a 4200 series Instron machine by pulling the castings out of the teeth. There were no significant differences in retention among the eight groups of parallel posts at alpha = 0.05. The testing procedure was repeated by using an 11 mm post with 6 degrees of taper. With tapered posts, a statistically significant reduction in retention was found in the lubricated samples when compared to the nonlubricated samples.

Analysis of Variance↗
PubMed1992

Seating and retention of complete crowns with a new adhesive resin cement.

The retentive property of cast gold complete crowns cemented with an adhesive resin cement (Panavia Ex) was compared with retention of crowns cemented with zinc phosphate cement (Flecks) and the conventional resin cement (Comspan). The effect of these agents on seating of crowns also was evaluated. Panavia cement exhibited the highest retentive strength, with values almost twice those obtained with zinc phosphate cement. However, the difference in mean retention values of crowns cemented with Comspan cement or with zinc phosphate cement was not statistically significant. Both resin cements used in this study provided better seating of crowns than did zinc phosphate cement.

Adhesives↗
PubMed1992

Effect of fluoride varnish on the retentive strength of provisional crowns luted with various temporary cements.

The retention of temporary crowns was studied with the use of a fluoride varnish (Duraphat) combined with various temporary cements. The mixture of Duraphat varnish and cement improved retention, with the exception of Opotow cement. Applying Duraphat varnish to the tooth surface before cementation enhanced the retentive strength of Tempbond, weakened the retention of Freegenol, but had no effect on Opotow cement. A "transfer effect" was observed, inasmuch as the Duraphat varnish encouraged adherence of the cement to the tooth structure rather than to the temporary crown.

Analysis of Variance↗
PubMed1992

Comparison of the retentive properties of a sleeve cast crown/core system with crowns cemented to conventional cast cores.

The retention of the crown to the core substructure is of great importance for a successful restoration. The aim of this study was to compare the retentive values of the Flexi-Cast post and its sleeve crown/core complex with that of a crown cemented to a conventional cast post. Forty single-rooted teeth divided equally into four groups were used. Flexi-Cast crown and cores were cemented to Flexi-Cast posts in groups 1 through 3. Group 4, the control group, comprised crowns cemented to conventional cast cores. Groups 1 through 4 had retentive values of 126.2, 135.5, 185.0, and 79.3 lb, respectively. Statistically, the increase in retention for all sizes of the Flexi-Cast crown and cores when compared with the control cast post and crown was found to be significant (p less than or equal to 0.0001).

Cementation↗
PubMed1992

Retentive properties of misaligned post attachment sleeves.

This study determined the retention of different sizes of attachment sleeves when cemented in various alignments with the corresponding post heads. This experiment was divided into six groups of eight samples, except for group 6, which had 10 samples. The retention was measured in pounds using a universal testing machine. In all samples, the malalignment of the sleeve to its corresponding post head did not cause loss of retention compared with the control. In groups 1 and 3, and 0.26 mm offset was introduced and this resulted in increased retention for sleeves to the No. 2 and No. 3 cast post heads. These values for the 0.26 mm offset were statistically significant compared with the control. This cast post system offers the dentist a greater safety factor.

Analysis of Variance↗
PubMed1992

Effects of temporary cementation on permanent cement retention to composite resin cores.

This in vitro study compared the effects on retention of base metal cylindrical retainers placed on composite resin cores when pretreated with eugenol and noneugenol temporary cements. Sixty composite cores and base metal cylindrical retainers were tested. The cores were pretreated with eugenol and noneugenol temporary cements before eventual cementation with resin and zinc phosphate cements. Cemented core retention was measured by application of a compressive force to the cores in an Instron machine. Differences were found between the two permanent cements. Pretreatment with eugenol cement reduced retainer retention with resin cements, but had no effect with zinc phosphate cement. Pretreatment with noneugenol cement did not reduce retainer retention.

Cementation↗
PubMed1993

Comparison of the retentive properties of two hollow-tube post systems to those of a solid post design.

The retention of a post in a root is critical for the successful restoration of an endodontically treated tooth. This study compared the retention of two hollow-tube post designs (Access post and World post) cemented with zinc phosphate cement or a titanium-reinforced composite resin cement (Flexi-Flow cement with titanium) with that of the control Para-Post system, a solid post design cemented with zinc phosphate cement. The experiment was divided into 11 groups of 10 samples. Retentive values were measured with a universal testing machine and the data were recorded in pounds. A one-way analysis of variance was computed and included Duncan's multiple comparisons test, Tukey's Student range test, and Dunnett's test. Duncan's multiple comparison test and Tukey's test were inconclusive. Only Dunnett's test revealed a significant difference between group 5, Access post, grooved dentin with Flexi-Flow cement with titanium (mean of 89.7 lb), and the control, group 11, Para-Post dowel cemented with zinc phosphate cement (mean of 61.3 lb). All other groups exhibited similar results with retentive values that ranged from 62 to 76 lb.

Acid Etching, Dental↗