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PubMed1975

Physical Factors in Denture Retention.

AAThis investigation was carried out to analyze the physical factors of saliva affecting denture retention. A model of examining denture retention is given by two parallel disks separated by a liquid layer. Metal, polyisobutylene (PIB) and poly (methyl methacrylate)(PMMA) were used instead of a denture and mucous membrane; and glycerol, olive oil and castor oil instead of saliva. The experiments were performed with three disk conditions: (1) Both upper and lower disks of metal, (2) both upper and lower disks of PMMA, (3) upper disk with PIB lining and lower of PMMA soley. A strain gauge was used in the experimental apparatus in order to obtain a measurement of high accuracy. In the experiments, the retentive forces developed in layers of 50 mu tickness were measured and compared with the values calculated from theoretical equations. The results are summarized as follows: (1)Retentive force must be resolved into static adhesive and separating forces, (2) surface tension of liquid may not highly influence the retention, and (3) viscosity of liquid plays an important role when two disks are separated.

Adhesiveness↗
PubMed2000

Efficacy of PSA in the detection of carcinoma of the prostate in patients presenting with acute urinary retention.

OBJECTIVES: A temporary elevation in serum-prostate specific antigen (PSA) levels has been reported in association with acute urinary retention. In spite of this, it is not uncommon for clinicians to assay PSA at the time a patient presents with acute urinary retention. We sought to evaluate whether this practice can be justified. PATIENTS AND METHOD: Fifty-four patients, aged between 55 and 89 years, who presented to a single institution with acute urinary retention were studied. A PSA assay was performed on admission and a record made of the prostatic size as assessed by digital rectal examination. All patients underwent a trial without catheter, those that failed to void underwent prostatic surgery whilst all others were followed up as outpatients. RESULTS: Five patients were found to have prostatic carcinoma, three following transurethral resection of the prostate (TURP) and two following needle biopsy, performed because of persistent elevation of the PSA. A significant elevation in the PSA was associated with acute urinary retention, with only 15 (28%) patients having a PSA of 4.0 ng/ml or less. This elevation reduced the sensitivity of PSA in detecting carcinoma of the prostate; even with a cut-off of 20 ng/ml, the positive predictive value of the test was only 21%. CONCLUSIONS: A PSA assay should not be performed at the time of presentation with acute urinary retention as it may lead to unnecessary investigations and anxiety for the patient. For those in whom a PSA assay is desirable a delay of 2 weeks should be allowed prior to sampling, as the half-life of PSA is known to be 2-3 days.

Aged↗
PubMedDate not supplied

Retention of a posterior resin-bonded fixed partial denture with a modified design: an in vitro study.

PURPOSE: The aim of this study was to test in vitro the resistance of a modified resin-bonded fixed partial denture (RBFPD) to detachment using a laboratory setup simulating load fatigue of mastication forces. The effect of varying the cement type was also investigated. MATERIALS AND METHODS: Extracted teeth were used to prepare specimens each consisting of a premolar and a molar with a space equivalent to a molar in between. Five test groups were prepared (n = 7). Specimens in group 1 were prepared to receive conventional RBFPDs with proximal grooves, occlusal rests, and lingual wings. Specimens in groups 2 and 3 were prepared to receive modified RBFPDs with retentive-slot restorations. Specimens in group 4 were prepared to receive RBFPDs with retentive-slot restorations only, whereas specimens in group 5 were prepared similarly to the ones in groups 2 and 3 but with inlay preparations instead of the retentive slots. Castings were made and their fit surfaces microetched. In groups 1, 2, 4, and 5 castings were cemented with Cement-It, whereas castings of group 3 were cemented with Panavia 21. Slot cavities of groups 2, 3, and 4 were restored with a resin composite. Specimens were subjected to compressive load cycling for 230,000 cycles at 4 Hz under water. Castings were then separated from the abutments under tensile loading. RESULTS: Mean separation forces were: group 1 = 361 N, group 2 = 525 N, group 3 = 562 N, group 4 = 449 N, and group 5 = 417 N. Groups 2 and 3 had significantly higher mean separation forces than groups 1 and 5. Separation of castings in groups 2 and 3 was associated with a higher frequency of cohesive fracture of the abutments than in group 1. Adhesive failure was uncommon among specimens of groups 2, 3, and 4. CONCLUSION: The modified RBFPDs of groups 2 and 3 had better potential for retention. Increased resistance to dislodgment of the modified RBFPDs was not directly related to the surface area of the castings, nor was it related to the type of resin cement, but rather to mechanical interlocking of the castings with the retentive-slot resin composite restorations.

Analysis of Variance↗
PubMed2001

Combined effect of context change and retention interval on interference in causality judgments.

Four experiments studied the effects of context change and retention interval on retroactive interference in human causal learning. Experiment 1 found evidence of retroactive interference. Experiment 2 found that either a 48-hr retention interval or a change in the context after the interference treatment decreased retroactive interference. An interaction between context change and retention interval effects was also found, eclipsing the context change effect after the 48-hr retention interval. Experiments 3 and 4 found additivity between context change and retention interval effects when participants were remained of the difference between physical contexts before the test, independently of whether the context change involved a return to the original acquisition context. These results add to the evidence suggesting that spontaneous forgetting is caused by a change in either the physical or the temporal contexts where information is acquired.

Adolescent↗
PubMed2001

Dynamic retentive force of a mandibular unilateral removable partial denture framework with a back-action clasp.

PURPOSE: The purpose of this study was to investigate the dynamic retentive force of a mandibular unilateral distal-extension partial denture framework with a back-action clasp that was designed in a buccally tilted cast on a dental surveyor. The retention mechanism of this framework was analyzed in comparison with other typical unilateral and bilateral frameworks for the mandibular Kennedy class II case. MATERIALS AND METHODS: Experimental gold alloy frameworks of three designs were repositioned to the master cast, and lifted upward to the vertical direction to the occlusal plane. The load required to dislodge each framework was recorded. The retentive force of each framework was determined by the maximum load in a dislodgment cycle. The bending strength of a plain clasp pattern of the same length as the clasp arm used in each framework was also measured by cantilever beam test. RESULTS: The mean retentive force of the unilateral framework with a back-action clasp of relatively low bending strength was significantly higher (P < 0.01) than that of the unilateral framework with two Akers clasps of relatively high bending strength, and 70 to 80% of the bilateral framework with two Akers clasps on the edentulous side and a double Akers clasp on the contralateral side. The unilateral framework with a back-action clasp showed the greatest early load resistance in the dislodgment cycle among the three designs. CONCLUSION: The reasonable retention mechanism was demonstrated by the unilateral framework with a back-action clasp.

Dental Abutments↗
PubMed2003

Managing older patients with urinary retention in the Continence Clinic.

OBJECTIVE: To evaluate the effectiveness of the Continence Clinic for managing retention of urine in older patients. DESIGN: Retrospective study. SETTING: Continence Clinic, Fung Yiu King Hospital, Hong Kong. SUBJECTS AND METHODS: Case notes of 58 patients seen at the Fung Yiu King Hospital Continence Clinic from October 1997 to September 2001 were reviewed. The patients had retention of urine with post-void residual volume of more than 200 mL, retention of urine requiring catheterization, or had catheters for unknown reasons. RESULTS: Urodynamic study performed for 22 (38%) patients showed that 12 had detrusor underactivity, six had detrusor hyperactivity with impaired contraction, and four had bladder outlet obstruction. Among the patients who were initially catheterized, the success rate for gradually stopping reliance on urinary catheterization was 84%. The success rate was higher among those who did not undergo urodynamic study than among those who had the study done (95% versus 67%; P=0.03). Reduction in post-void residual volume was observed at the last clinic visits (P<0.0001). Moreover, significant decreases in post-void residual volume were found both for patients who did and did not have urodynamic study. CONCLUSION: Most of the older patients with urinary retention with or without indwelling catheters were treated successfully in the Continence Clinic by appropriate medical therapy. Urodynamic study can be performed for selected patients when managing urinary retention.

Aged↗
PubMed2001

[Bonding and mechanical interlocking of three kinds of luting cements in retention of complete metal crowns].

OBJECTIVE: To evaluate the effects of bonding and mechanical interlocking of three kinds of luting cements in the retention of complete metal crowns. METHODS: Zinc phosphate cement (ZP), glass ionomer cement (GI) and polycarboxylate cement (PC) are in common use for clinical treatment. In this study, these cements were selected to bond the complete crowns to molars in vitro. The retention capacities of the complete crowns were tested and compared. And apart from mechanical interlocking, the effect of bonding was tested. On this basis the interlocking capacity of the cement was calculated. RESULTS: 1. The retention capacities of complete metal crowns from the highest to least were: GI > ZP > PC. 2. The proportions of mechanical interlocking of ZP, GI and PC in the retention of complete metal crowns were 62.6%, 48.3% and 20.1% and the ratios of bonding of ZP, GI and PC were 37.4%, 51.7% and 79.9%, respectively. CONCLUSION: The effects varied with different cements in the retention of complete metal crowns because of the discrepancy in bonding and mechanical interlocking properties. Mechanical interlocking plays a prominent role when ZP or GI is used, and the role of bonding is apparent in PC.

Adhesives↗
PubMed2003

Acute urinary retention after use of assisted reproductive technology. A report of 2 cases.

BACKGROUND: Urinary retention in women is an unusual occurrence. Various conditions can cause it, including surgery, childbirth, pelvic masses, procidentia, vulva hematoma, incarceration of a gravid uterus, urologic disease, neurogenic disease and psychiatric disorders. CASES: Two infertile women underwent assisted reproductive technology (ART) and luteal-phase support during which acute urinary retention occurred. The patients were evaluated by means of physical examination, urodynamic study and determination of serum progesterone levels. Bladder distention was found during luteal-phase support. Urodynamic studies revealed detrusor areflexia. Serial serum progesterone levels were > 100 ng/mL. CONCLUSION: Cases of acute urine retention during luteal-phase support are rarely reported. Urine retention should be considered in the differential diagnosis when abdominal pain occurs after patients undergo ART. Transient elevation of the progesterone level may be the cause of the acute urine retention.

Acute Disease↗
PubMedDate not supplied

Retention and failure morphology of prefabricated posts.

PURPOSE: This study evaluated the effect of cement, post material, surface treatment, and shape (1) on the retention of posts luted in the root canals of extracted human teeth and (2) on the failure morphology. MATERIALS AND METHODS: Posts of titanium alloy (ParaPost XH), glass fiber (ParaPost Fiber White), and zirconia (Cerapost) received one of several surface treatments-sandblasting, CoJet treatment, application of Metalprimer II, or sandblasting followed by silane application-and were then luted in the prepared root canal of human incisors and canines (n = 10). Following water storage at 37 degrees C for 7 days, retention was determined by extraction of the posts. Failure morphology of extracted posts was analyzed and quantified stereomicroscopically. RESULTS: Type of luting cement, post material, and shape of post influenced the retention and failure morphology of the posts. Because of limited adherence of the cement to the root canal, surface treatments did not always have a positive effect on retention. CONCLUSION: Choice of luting cement was critical for all three types of posts. Parallel posts showed superior retention to tapered posts.

Analysis of Variance↗
PubMed2006

[Survey of treatment-seeking complete denture wearers concerning tooth loss, retention behavior and treatment expectations].

The aim of the current study was to gather information about time and etiology of tooth loss, and to analyze the reasons for treatment needs with a questionnaire used among edentulous patients. 60 patients (age 44-98 years) who requested dental treatment were included. More than half of the patients were edentulous before the age of 60, in almost all cases the maxilla was affected first. This difference was more pronounced in women, who experienced tooth loss in the maxilla 17 years prior to the mandible. At the time of edentulism women were about ten years younger than men. According to patients'report, periodontal disease was the most common reason for tooth loss. In the mandible, prosthesis retention was influenced by alveolar ridge resorption, while in the maxilla there was no relation between the amount of resorption and perceived retention. This indicates that maxillary prostheses retention is influenced by other factors besides the alveolar ridge morphology. So, permanent intake of drugs potentially causing xerostomia was related to poorer assessment of prostheses retention in the upper jaw. The results of the questionnaire "Patient satisfaction related to prosthetic restoration" before treatment indicated that the general satisfaction with the existing complete denture in the mandible was influenced by functional problems and the impairment of patients'self-confidence (R-squared = 0.754). The main reason for requesting treatment was the poor retention of the lower denture. More than half of the participants stated that they refrained from eating certain foods due to a reduced chewing ability.

Adult↗
PubMed2006

[The effects of remain of residual tooth on retention of post-core crown system].

This study was aimed to assess the effects of remain of residual tooth on the retention of postpost-core was made,casted and cemented. The post-core was tested at the speed of 10 mm/min on the Instron4302, and the retention force was recorded. Other samples were made and subjected to the test for cohesion of polymethylmethacrylate and metal. The result showed that retention significantly increased with the adding of the residual tooth. When the length of post was longer than 8 mm and 1 mm was added to tooth remain, the difference in retention between the two groups was statistically significant. It was noted that there existed relationships of retention to length of post and tooth remain, of cohesion to length of post and tooth remain, and of frictiion resistence to length of post and tooth remain; moreover, the relevant linear regression equations were obtained. So during the tooth preparation of post-core system, the tooth tissue should be reserved as much as possible.

Crowns↗
PubMedDate not supplied

Postpartum urinary retention.

BACKGROUND: Urinary retention is a common and frustrating complication in women during the immediate postpartum period. Physiologic changes in the bladder that occur during pregnancy predispose patients to develop symptomatic retention of urine during the first hours to days after delivery. METHODS: The incidence and characteristics of postpartum urinary retention were researched through a literature review and are illustrated by a case report. RESULTS AND CONCLUSIONS: Postpartum urinary retention has a reported incidence ranging from 1.7 to 17.9 percent. Factors associated with postpartum urinary retention include (1) first vaginal delivery, (2) epidural anesthesia, and (3) Cesarean section. Treatment begins with supportive measures to enhance the likelihood of micturition, such as ambulation, privacy, and a warm bath. If these measures are not successful, catheterization can be performed. If the bladder contains more than 700 mL of urine, prophylactic antibiotics may be warranted, because prolonged or repeated catheterization may be necessary.

Adult↗
PubMed1990

Retentive strength of six temporary dental cements.

The retentive strength of three zinc oxide-eugenol cements and three noneugenol-containing zinc oxide cements and the effect of the addition of petrolatum on retention were tested. The addition of petrolatum was found to affect retention of the cements significantly. Retention strengths varied from 1.6 kg to 40.0 kg. Of the Class 1, Type 2, systems tested, noneugenol cements had higher retentive values than did the eugenol-containing cements.

Analysis of Variance↗
PubMed1989

[Retention of Pt-Co magnet for dental prosthesis].

Though Pt-Co magnet is inferior to rare-earth magnet in magnetic properties, the magnet is much superior to the corrosional resistances in oral fluids. The purpose of this investigation was to determined the retentive characteristics of Pt-Co magnet. The break away force between the magnet and XM27 stainless steel keeper were measured. The retention of phi 4x 1.5 mm Pt-Co magnet was 49 g. This retention could be increased to 172 g by using stainless steel cup type yoke. These retention were rather small, but if 3 or more couples of attachments or larger Pt-Co magnet attachment were fixed in denture, the retention level approach that of clasp or mechanical precision attachments.

Cobalt↗
PubMed1985

Effects of D-galactosamine and D-glucosamine on retention performance of a brightness discrimination task in rats.

The glycoprotein and ganglioside precursors D-galactosamine and D-glucosamine were tested for effects on acquisition and retention of a brightness discrimination reaction in rats. Intraperitoneally (1.85 mmoles/kg) and intraventricularly (0.8 mumoles) applied D-galactosamine had no influence on acquisition, but improved the retention performance. Intraperitoneally (6.0 mmoles/kg) and intraventricularly (2.4 mumoles) applied D-glucosamine showed qualitatively identical results, i.e. improving effect on retention performance. The penetration abilities of [3H]D-glucosamine and [3H]N-acetyl-D-glucosamine to cross the blood-brain barrier were tested: D-glucosamine penetrated easily the blood-brain barrier (approximately 2:1 relation). However, after intravenous application of 200 mumoles 30 min before training both substances showed a positive effect on retention performance. The findings are discussed in the light that the retention-improving effects of the hexosamines under investigation are believed to be due to a direct, activating influence on glycoprotein and/or ganglioside syntheses in the brain.

Amino Sugars↗
PubMed1993

Postoperative retention of urine in general surgical patients.

OBJECTIVE: To find out the incidence of retention of urine after various general surgical operations, and to assess the effects of applying a bag filled with warm water (40-45 degrees C), and encouraging early mobilisation onreducing the necessity for catheterisation. DESIGN: Open study. SETTING: Cumhuriyet University Hospital, Sivas, Turkey. SUBJECTS: 577 consecutive patients who had no history of urinary problems and had not already been catheterised, and who underwent general surgical operations between April 1989 and December 1991. MAIN OUTCOME MEASURE: Ability to pass urine spontaneously. RESULTS: 64 of 272 men (24%) and 47 of 305 women (15%) developed retention of urine (p = 0.02), and 15 and 11, respectively, required catheterisation. Patients were most likely to develop retention after repair of incisional hernia (13/32, 38%), midline laparotomy (19/82, 23%), and subcostal incisions (30/142, 21%), but there were no significant differences among these. Significantly more patients whose operations had lasted 60 minutes or more, and who had opiate analgesia, required catheterisation (5/232 compared with 21/345, p = 0.04, and 11/120 compared with 15 out of 457, p = 0.01, respectively). 85 of the 111 patients who went into retention (77%) were able to pass urine spontaneously after application of a bag containing warm water to the suprapubic region, and walking about. The mean period of catheterisation was 12 hours (range 4-76), and all patients but one passed urine spontaneously when the catheter was removed. Only two of the 26 patients who were catheterised developed microbiologically confirmed urinary tract infections. CONCLUSION: Retention of urine is a common complication after general surgical operations, but the necessity for catheterisation can be kept to a minimum by simple and inexpensive measures.

Adolescent↗
PubMed1993

Cholinergic modulation of spatial working memory of mice in radial maze performance: retention curve analysis.

Cholinergic modulation of the spatial working memory of mice was investigated in an eight-arm radial maze. The mice were trained to achieve a stable baseline level of performance, and the retention of spatial working memory was then examined by means of imposition of retention intervals of 45, 90, 180, and 360 min between choices four and five. The animals were removed from the apparatus during these intervals. The effects of oxotremorine (0.025-0.1 mg/kg, ip), physostigmine (0.025-0.1 mg/kg, ip), and scopolamine (0.1-0.4 mg/kg, ip) on the number of the correct responses after the various time intervals (5-8 choices) were studied. Mice received drug injections 30 min prior to the first four arm-choices before delay intervals (1-4 choices). The number of correct responses after the intervals decreased with the increased length of the retention interval. Oxotremorine and physostigmine exhibited dose-dependent stimulating effects of resistance to decreases in the number of correct responses, but scopolamine potentiated the decline in a dose-dependent manner. Significant interactions between the effects of cholinergic drugs and the length of retention over time were also observed. These observations indicate a cholinergic modulation of spatial working memory in mice engaged in radial maze performance, as assessed by means of retention curve analysis.

Animals↗
PubMed1993

Effects of response strategy and retention interval on performance of Clark's nutcrackers in a radial maze analogue.

Two groups of Clark's nutcrackers (Nucifraga columbiana) were trained to use either a stay or shift response strategy in a radial maze analogue. Each trial had a preretention stage, a retention interval, and a postretention test. In Experiment 1, acquisition with a 5-min retention interval was studied. Response strategy did not affect the rate at which the task was learned. Performance following longer retention intervals was tested in Experiments 2-4. Changes in retention intervals were presented in trial blocks of increasing duration in Experiment 2 and were randomly presented between trials in Experiment 3. Experiment 4 extended the retention interval to 24 hr. No difference in performance was found between the 2 groups in any of these experiments. These results suggest a flexible relationship between spatial memory and response requirement in food-hoarding birds for at least 1 spatial memory task.

Animals↗