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PubMed2000

Effect of root canal sealers and irrigation agents on retention of preformed posts luted with a resin cement.

This study examined the effect of three sealers and four irrigants on retention of Dentatus preformed posts luted with Panavia 21 resin cement. Gutta-percha with one of the following sealers--EWT, AH26, Nogenol, or no sealer (control)--was used to fill the root canals of 160 autoclaved incisor and premolar tooth roots. After 72 hr 8 mm post spaces were created with Dentatus Probos Pathfinders and Dentatus reamers. After irrigating the post spaces with saline, 5.25% NaOCl, 50% citric acid followed by NaOCl, or 40% H3PO4, followed by NaOCl, Panavia 21 TC cement was introduced into the canal on the Dentatus #4 stainless steel post's threads. An up-and-down and counterclockwise motion and then a forward twist seated the posts without engaging dentin. Mesiodistal and faciolingual radiographs visualized the chambers. After 72 hr posts were removed axially with an Instron at 5 mm/min. Surprisingly, using Nogenol sealer reduced post retention whereas EWT and AH26 increased retention compared with no sealer. Post retention improved after acid etchants, especially for AH26.

Acid Etching, Dental↗
PubMed2001

Post retention: the effect of sequence of post-space preparation, cementation time, and different sealers.

Many endodontic sealers contain constituents that have been shown to inhibit the polymerization of resin cements. This may be important when prefabricated posts are cemented at the same appointment as root canal obturation. This study evaluated the effects of cementing posts with a resin cement immediately or at a delayed time period after obturation using Roth's 801 Elite Grade or AH26 sealer cements. The contribution of mechanical post-space preparation was also assessed as a critical variable. One hundred twenty extracted canines were randomly divided into eight experimental groups. The variables evaluated were the order of post preparation (either before or after obturation), the type of sealer used, and the time of post cementation. All teeth received a stainless steel #6 Parapost XP cemented with a resin cement, Panavia 21. Each experimental group underwent tensile testing for retention using an Instron universal testing machine. For both sealers posts cemented in teeth in which the canal was obturated before post-space preparation and thus had sealer-contaminated dentin removed by the space preparation procedure had significantly higher retentive values than those obturated after post-space preparation in which contaminated dentin might remain. Sealer used and time of cementation had no specific effect on retention. Achieving a clean, "freshened" dentinal surface during mechanical post-space preparation seems to be a critical variable for post retention when a resin cement is used.

Analysis of Variance↗
PubMed2001

Efficacy of sacral nerve stimulation for urinary retention: results 18 months after implantation.

PURPOSE: We investigate the efficacy of sacral neurostimulation in patients with idiopathic urinary retention in a prospective, randomized multicenter trial. MATERIALS AND METHODS: A total of 177 patients with urinary retention refractory to standard therapy were enrolled in the study. Greater than 50% improvement in baseline voiding symptoms during a 3 to 7-day percutaneous test stimulation qualified a patient for surgical implantation of an InterStim parallel system. Of the patients who qualified for implantation 37 were randomly assigned to a treatment and 31 to a control group. Patients in the treatment group underwent early surgical implantation of the sacral nerve stimulation system, while implantation was delayed in the control group for 6 months. Followup evaluations, including voiding diary analysis and temporary deactivation of the stimulator at 6 months, were conducted at 1, 3, 6, 12 and 18 months after implantation in the treatment group, and after 3 and 6 months in the control group. RESULTS: Compared to the control group, patients implanted with the InterStim system had statistically and clinically significant reductions in the catheter volume per catheterization (p <0.0001). Of the patients treated with implants 69% eliminated catheterization at 6 months and an additional 14% had a 50% or greater reduction in catheter volume per catheterization. Therefore, successful results were achieved in 83% of the implant group with retention compared to 9% of the control group at 6 months. Temporary inactivation of sacral nerve stimulation therapy resulted in a significant increase in residual volumes (p <0.0001) but effectiveness of sacral nerve stimulation was sustained through 18 months after implant. CONCLUSIONS: Results of this prospective, randomized clinical study demonstrate that sacral nerve stimulation is effective for restoring voiding in patients with retention who are refractory to other forms of treatment.

Adult↗
PubMedDate not supplied

Sacral neuromodulation for urinary retention caused by sexual abuse.

OBJECTIVE: This case report describes the use of sacral neuromodulation to treat urinary retention after sexual abuse. METHODS: Sacral neuromodulation was added to therapeutic regimen of a 38-year-old woman in whom chronic, complete urinary retention developed after psychological and sexual abuse during childhood. RESULTS: The combination of psychotherapy and neuromodulation restored the patient's ability to void, whereas psychotherapy alone had not. CONCLUSIONS: Although a multifactorial etiology of retention cannot be ruled out in this patient, neuromodulation might effectively treat urinary retention in cases of a conversion disorder after sexual abuse.

Adult↗
PubMed1995

The effect of cementing agent and technique on the retention of a CeraOne gold cylinder: a pilot study.

Endosseous dental implants are routinely used for the replacement of missing teeth. The CeraOne system uses a gold cylinder that is luted to a metal abutment. This study evaluated two luting agents and two luting techniques on the retention of a CeraOne gold cylinder to a CeraOne titanium abutment. A mechanical testing instrument was used to provide an uniaxial tensile force on the gold cylinder, which was cemented with zinc phosphate or Tempbond NE. The access opening to the gold abutment screw was filled or unfilled. Filling the access opening resulted in significantly higher retentive values (P < 0.01) compared to leaving the access opening unfilled. The gold cylinder was significantly more retentive when cemented with zinc phosphate as compared with Tempbond NE (P < 0.01). A Tukey post hoc test demonstrated that all means were significantly different at the P = 0.01 level. The results suggest that the choice of luting agent and luting technique may affect retention of a CeraOne gold cylinder.

Analysis of Variance↗
PubMed2005

Bilateral extravesical ureteral reimplantation in toilet trained children: Is 1-day hospitalization without urinary retention possible?

PURPOSE: Bilateral extravesical ureteral reimplantation has been associated with urinary retention. We developed a critical pathway and modification of surgical technique to determine whether the bilateral extravesical procedure could be performed in toilet trained children with patients discharged home after a 1-day hospitalization and without urinary retention. MATERIALS AND METHODS: A total of 50 consecutive toilet trained children were evaluated after undergoing bilateral extravesical ureteral reimplantation using a modified technique that limits ureteral dissection, ureteral mobilization and detrusor dissection to as distally as possible so that a 5:1 ratio of tunnel length to ureteral diameter can be accomplished. No surgical dissection occurs in proximity to the obliterated umbilical artery, nor is the artery ligated. Patients follow a strict postoperative critical pathway, and parents receive extensive preoperative and postoperative education. A child is required to fulfill 5 strict criteria to be discharged from the hospital. RESULTS: Patient age ranged from 1.9 to 12.8 years (mean 4.9), with 37 girls and 13 boys participating. All patients were discharged home on postoperative day 1. All patients were able to void postoperatively without any instances of urinary retention. None of the children had acute urinary tract infections or required rehospitalization. All patients had radiographic resolution of the vesicoureteral reflux on postoperative voiding cystourethrogram. CONCLUSIONS: To our knowledge this is the first study to demonstrate that bilateral extravesical ureteroneocystostomy can be performed in selected patients without postoperative urinary retention and with uniform hospital discharge in 1 day. The critical pathway and limited dissection extravesical approach are essential for this success.

Child↗
PubMedDate not supplied

Impaired memory retention and decreased long-term potentiation in integrin-associated protein-deficient mice.

Previously, we have demonstrated that integrin-associated protein (IAP) mRNA level is approximately fourfold higher in rats showing good retention performance (600 sec) than rats showing poor retention performance (< 80 sec) in an inhibitory avoidance learning paradigm. In the present study, we have used the gene-targeted IAP-deficient mice to further investigate the role of IAP involved in memory formation and hippocampal long-term potentiation (LTP) in vivo. Results revealed that there was a significant impairment in memory retention and a significant reduction in the magnitude of LTP in IAP-deficient mice when compared with the wild-type and heterozygote mice, whereas the wild-type and heterozygote animals did not show marked differences on these measures. Furthermore, the impairment in retention performance of IAP-deficient mice was not due to different sensitivities of these animals to the electric shock. When we examined locomotor activity and rotarod treadmill performance, no differences were observed among these three groups of animals either. Western blot analysis confirmed the lack of IAP protein in IAP-deficient mice, whereas IAP expression was similar in both the wild-type and heterozygote controls. These results together demonstrate that IAP plays an important role in the process of memory formation and synaptic plasticity in mice.

Animals↗
PubMed2005

Nurses' knowledge and skill retention following cardiopulmonary resuscitation training: a review of the literature.

AIM: This paper reports a literature review examining factors that enhance retention of knowledge and skills during and after resuscitation training, in order to identify educational strategies that will optimize survival for victims of cardiopulmonary arrest. BACKGROUND: Poor knowledge and skill retention following cardiopulmonary resuscitation training for nursing and medical staff has been documented over the past 20 years. Cardiopulmonary resuscitation training is mandatory for nursing staff and is important as nurses often discover the victims of in-hospital cardiac arrest. Many different methods of improving this retention have been devised and evaluated. However, the content and style of this training lack standardization. METHOD: A literature review was undertaken using the Cumulative Index to Nursing and Allied Health Literature, MEDLINE and British Nursing Index databases and the keywords 'cardiopulmonary resuscitation', 'basic life support', 'advanced life support' and 'training'. Papers published between 1992 and 2002 were obtained and their reference lists scrutinized to identify secondary references, of these the ones published within the same 10-year period were also included. Those published in the English language that identified strategies to enhance the acquisition or retention of Cardiopulmonary resuscitation skills and knowledge were included in the review. RESULTS: One hundred and five primary and 157 secondary references were identified. Of these, 24 met the criteria and were included in the final literature sample. Four studies were found pertaining to cardiac arrest simulation, three to peer tuition, four to video self-instruction, three to the use of different resuscitation guidelines, three to computer-based learning programmes, two to voice-activated manikins, two to automated external defibrillators, one to self-instruction, one to gaming and the one to the use of action cards. CONCLUSIONS: Resuscitation training should be based on in-hospital scenarios and current evidence-based guidelines, including recognition of sick patients, and should be taught using simulations of a variety of cardiac arrest scenarios. This will ensure that the training reflects the potential situations that nurses may face in practice. Nurses in clinical areas, who rarely see cardiac arrests, should receive automated external defibrillation training and have access to defibrillators to prevent delays in resuscitation. Staff should be formally assessed using a manikin with a feedback mechanism or an expert instructor to ensure that chest compressions and ventilations are adequate at the time of training. Remedial training must be provided as often as required. Resuscitation training equipment should be made available at ward/unit level to allow self-study and practice to prevent deterioration between updates. Video self-instruction has been shown to improve competence in resuscitation. An in-hospital scenario-based video should be devised and tested to assess the efficacy of this medium in resuscitation training for nurses.

Cardiopulmonary Resuscitation↗
PubMed1994

Some clinical investigations on retention forces of maxillary complete dentures with the use of denture fixatives.

The aim of this study was to evaluate objectively and clinically the relative improvement in retention forces of complete dentures with the use of three proprietary denture fixatives. Using the UCL Retentiometer, retention forces of ill-fitting maxillary complete dentures were measured with saliva alone as the interface medium and with the use of the three test denture fixatives in edentulous subjects over a period of 6 h. Results showed that forces with saliva alone were consistently and significantly lower when compared with the forces measured at any test period with the use of the test fixatives. A sixfold improvement in forces from the salivary baseline values was observed when these materials were used. However, the test fixatives showed substantial variations in retention forces depending on the physical formulation of the material. Whilst the powder variety was effective immediately after its application, retention forces with the liquid and paste materials did not peak until 3 h post-insertion. Measurements at 6 h post-insertion stage showed that the powder fixative was the least effective of the three materials. This was mainly attributed to the rapid washing of the active ingredients by saliva because of the absence of oily base present in the paste and liquid materials.

Adhesives↗
PubMed1995

Cutting the cost of catheterization for acute retention--a hospital or domiciliary procedure?

OBJECTIVE: To report the views of General Practitioners (GPs) and patients on the most appropriate place and person to catheterize patients in acute urinary retention. PATIENTS AND METHODS: Two separate questionnaires were sent to 50 local GPs and 100 patients who had recently been referred with acute urinary retention. The questionnaires were designed to ascertain the most appropriate place and person to catheterize these patients. They also established the number of hospital admissions due to acute retention, the use of ambulances and the uptake of the district nurse services. RESULTS: Whilst 54% of GPs advocated domiciliary catheterization, only 20% of emergency catheterizations were carried out in the home. Nearly half the patients catheterized in the Accident and Emergency Department were admitted acutely and 41% of patients had travelled to hospital by ambulance. Patients were equally divided about where they would prefer to be catheterized, but 70% of patients stated that they were happy to be catheterized by a trained nurse; no GP opposed this concept. CONCLUSION: The cost/benefit analysis of these results strongly supports the case for establishing best-practice guidelines to promote an emergency domiciliary service led by GPs and trained district nurses and thus hasten the emergency care of acute retention and cut costs.

Acute Disease↗
PubMed2000

Reduction in renal haemodynamics by exaggerated vesicovascular reflex in rats with acute urinary retention.

1. We examined the possibility that a vesicovascular reflex is exaggerated by acute urinary retention, and that the increase in renal vascular resistance caused by this reflex may lead to renal dysfunction. We evaluated the vesicovascular responses to normal micturition (NM, transcystometric condition) and acute urinary retention (isovolumetric condition mimicking complete bladder-outlet obstruction (CBOO) and partial urethral ligation mimicking partial bladder-outlet obstruction (PBOO)) in anaesthetized female Wistar rats. 2. Acute urinary retention due to CBOO or PBOO provoked a prolonged or increased intravesical pressure, an enhancement in both bladder pelvic afferent and bladder pelvic efferent nervous activity, and an elevation in mean arterial blood pressure. 3. Single-unit analysis showed that these vesicovascular reflexes were triggered by activation of low-threshold and high-threshold bladder mechanoreceptors, but not by renal uretropelvic mechanoreceptors. 4. Bladder contraction in CBOO and PBOO conditions and graded increases in bladder volume significantly reduced renal blood flow and cortical microvascular blood flow. The acute urinary retention-induced renal vasoconstriction was mediated by the renal nerve. Renal denervation, but not bilateral ureteral resection, abolished the renal vasoconstriction associated with the vesicovascular reflexes. 5. These findings indicate that exaggerated activation of bladder afferents exerts a positive feedback effect to increase sympathetic outflow to the kidney further, thereby contributing to significant renal vasoconstriction via a renal nerve-dependent mechanism.

Afferent Pathways↗
PubMed1991

Effects of potentially phobic conditioned stimuli on retention, reconditioning, and extinction of the conditioned skin conductance response.

Discriminative classical conditioning of skin conductance responses (SCRs) was studied in 163 college students as a function of four variables: CS type (potentially phobic versus neutral conditioned stimuli), Sex of the subject, Interstimulus interval (ISI) during conditioning (.5 versus 8 s), and Retention interval between conditioning and retention assessment (1 versus 6 months). CS type did not affect acquisition, retention, or reconditioning of the differential conditioned responses. The effect of CS type was highly significant during extinction, with differential SCRs to CS+ and CS- being greater with potentially phobic conditioned stimuli. This was true for both sexes, both the .5-s and the 8-s ISI, and after a 1-month or a 6-month retention interval. Moreover, SCRs conditioned to phobic conditioned stimuli with the .5-s ISI persisted even after subjects' cognitive expectancy of the UCS, which was measured on a trial-by-trial basis, had completely extinguished. The results indicate that the effect of potentially phobic conditioned stimuli on the conditioned skin conductance response is unique to resistance to extinction-they affect not learning but unlearning of the autonomic response.

Adult↗
PubMed1993

Clasp retention: the effects of five variables.

An attempt was made to determine the relative retention of each of the four most commonly used clasp assemblies. They are the rest, proximal plate, I bar (RPI); rest, proximal plate, facial circumferential arm (RPA); modified T; and Akers (facial and lingual circumferential arms). A mandibular bilateral distal extension base removable partial denture design was selected because it is most commonly used. A test model was made by removing all mandibular molars from a Columbia Dentoform and replacing the ivorine second bicuspids with natural teeth. These, in turn, were later replaced with gold crowns that were identical in contour to the natural teeth. Eight removable partial dentures were constructed using preformed plastic lingual bars, minor connectors, denture base retention loops, and clasps. Artificial teeth and the denture bases were processed to each framework as for a clinical patient. Each removable partial denture was placed in the Instron testing machine and pulled from the test model. The investigation examined the effectiveness of each of four types of clasps in resisting displacing forces, in both vertical (occlusal) and mesio-occlusal directions. Each clasp was tested using natural teeth and gold crowns, in dry and wet environments, both with and without indirect retainers. Results indicate that, (1) The RPA clasp was the most retentive of all on natural abutments, against both directions of pull, but only slightly so over the RPI clasp with a vertical pull. (2) The Akers clasp was most retentive against a mesio-occlusal pull on the gold abutments. (3) Natural tooth structure gives slightly more frictional resistance than a gold surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Crowns↗
PubMed1994

The effect of tooth preparation on retention and microleakage of cemented cast posts.

PURPOSE: Vibration from the high-speed handpiece may adversely affect the cement layer between a casting and a tooth, causing loss of retention or increased microleakage. This study assessed the effect of crown preparation on retention and microleakage of cemented cast post and cores. MATERIALS AND METHODS: Post and cores were fabricated for extracted teeth and cemented. Specimens were prepared for crown restorations, varying the preparation time and the rotary diamond instrument used. After thermocycling and immersion in a dye bath, tensile unseating force and linear dye penetration were measured. RESULTS: In general, retention decreased with increased severity of crown preparation; however, differences were not statistically significant (alpha = .05). Although the differing preparation conditions resulted in significant differences in microleakage, no consistent trends were evident. CONCLUSIONS: Crown preparation using high-speed rotary diamond abrasives of cast post and cores luted with zinc phosphate cement had no significant effect on their retention, but had varying effects on subsequent microleakage at the cement-tooth interface.

Analysis of Variance↗
PubMed1994

The relationship between preparation convergence and retention of extracoronal retainers.

PURPOSE: Although traditional ideal convergence (the sum of taper of the opposite sides) for crown preparation has been arbitrarily set at 4 degrees to 10 degrees, some believe absolute parallelism yields the highest retention. This study examined the relationship between the degree of convergence of a machined metal die and the retention of its casting. MATERIALS AND METHODS: The method used was that of cementing cast metal crowns onto full crown preparations on brass dies with varying convergence angles, and then recording the force required to remove the crowns from the dies in a vertical direction using a Tate-Emery Testing Machine and Load Indicator. RESULTS: It was found that retention (i.e., the force needed to remove the cemented castings from the die in their common long axis) increases from 0 degree convergence to peak between 6 degrees to 12 degrees convergence. It also seems that a critical film thickness does exist for optimum retention, and that film thicknesses smaller than the critical thickness may be responsible for the phenomenon that we have observed and directly related to the convergence angle itself. CONCLUSIONS: There seems to be experimental data supporting the use of traditionally taught convergence. Our study found that convergence angles between 6 degrees and 12 degrees seem to be optimum for tooth crown preparation when one plans to use zinc phosphate cement. Convergence angles of less than 6 degrees may not be desirable even if they can be clinically achieved. The results of our study indicate that a relationship exists between the convergence angle and the critical cement thickness that is necessary to realize the maximum strength properties of zinc phosphate cement.

Analysis of Variance↗
PubMed2002

Effect of dowel space preparation and composite cement thickness on retention of a prefabricated dowel.

PURPOSE: This investigation examined what effect cement thickness had on retention of prefabricated endodontic dowels luted with a composite resin cement (Panavia 21 OP; J Morita, Irvine, CA) into canals previously obturated with gutta percha and a eugenol-based sealer. MATERIALS AND METHODS: Sixty-four single-rooted teeth were decoronated, filed, cleaned, and sequentially shaped with sizes 2-5 Gates Glidden drills (Dentsply/Maillefer, Tulsa, OK) and 0.12 taper rotary instrumentation. Teeth were then divided into 4 groups of 16 specimens each. All specimens were obturated with gutta percha and a eugenol-based sealer. Dowel space preparation and dowel cementation were completed 1 week after obturation. Ten-millimeter-deep dowel spaces were prepared using dowel drills with 4 different diameters: size 5 Parapost drill (Group 1; Coltene/Whaledent, Mahwah, NJ); size 5.5 Parapost drill (Group 2; Coltene/Whaledent); size 6 Gates Glidden drill (Group 3; Dentsply/Maillefer); size 6 Parapost drill (Group 4; Coltene/Whaledent). Size 5 Paraposts were then cemented with Panavia 21 OP. After 48 hours of storage, specimens were mounted in polyvinyl chloride (PVC) pipe with acrylic, and the dowels were removed in tensile mode using a universal testing machine at 1 mm/min, with data recorded in kilograms. RESULTS: (all values in kilograms) Group 1 (Parapost 5) mean = 15.07, 95% confidence interval (CI) = +/-6.11; Group 2 (Parapost 5.5) mean = 25.60, 95% CI = +/-7.39; Group 3 (Gates-Glidden 6) mean = 43.15, 95% CI = +/-7.81; Group 4 (Parapost 6) mean = 37.75, 95% CI = +/-6.35. Analysis of variance and Bonferroni tests revealed that Group 3 had significantly greater mean retention strength values than Group 1 and Group 2 (p <.05), and that Group 4 had significantly greater mean retention strength values than Group 1 (p <.05). CONCLUSIONS: Paraposts cemented with Panavia 21 OP showed significantly greater retention in oversized dowel spaces compared with dowel spaces prepared with the manufacturers' matched dowel-drill set.

Analysis of Variance↗
PubMed1993

Crown retention and cyclic loading (in vitro).

Cast gold crowns were luted on extracted and prepared human teeth with zinc phosphate cement and subjected to a fatigue test by cyclic loading. The correlation between crown retention and three retention variables was determined by the fatigue test. The results show that the smallest convergence angle tested, 20 degrees, gave better retention than did angles of 40 degrees and 60 degrees, and that surface roughness, surface size, height, and base diameter of the preparations had no influence on crown retention within the parameter sizes tested.

Crowns↗
PubMed1977

Angiotensin injected into the neostriatum after learning disrupts retention performance.

Angiotensin II, injected into the dorsal neostriatum of rats 5 minutes after they had learned a passive avoidance task, disrupted the retention of the task 24 hours later. Identical neostriatal injections given 22 hours after learning (2 hours before retention) were without effect on retention performance. Ventral neostriatum or posterior thalamus were ineffective sites for injection of angiotensin. Injection of thyrotropin releasing hormone or lysine-8-vasopressin into the dorsal neostriatum was ineffective. These findings indicate a possible role for endogenous angiotensin in the neostriatum on retention performance and suggest potential involvement in mnemonic processes.

Angiotensin II↗