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PubMed2004

Retention force of complete palate coverage and palate-less dentures in vitro.

The purpose of this study was to investigate the retention force of complete palate coverage and palate-less dentures made with three polymerization systems (DS system, SR-Ivocap system, microwave polymerization system) in vitro. The retention force between each denture and a polyurethane model by intervening artificial saliva was measured using a tensile tester. In addition, discrepancies between the denture base and the stone cast were measured at several points. The retention force of complete palate coverage and palate-less dentures made with the 3 polymerization systems shows that the DS system had a greater retention force than the SR-Ivocap system and the microwave system. Moreover, the retention force of palate-less dentures was greater than that of complete dentures only in the case of the DS system. The interaction of the polymerization system and the denture type also had a statistically significant effect on the retention force. Dentures made with the DS system had smaller discrepancies compared with dentures processed with the other systems. The retention force correlated very closely with discrepancies at the denture border and the residual ridge.

Acrylic Resins↗

PubMed2001

Bladder dysfunction after acute urinary retention in rats.

PURPOSE: We investigated bladder function in acute urinary retention and subsequent catheterization in rat bladders. MATERIALS AND METHODS: The penile urethra in rats was clamped with a small clip and cystostomy was performed to infuse 3 ml. of saline for inducing acute urinary retention. At 30 minutes after the induction of urinary retention the cystostomy was opened to empty the bladder. In functional studies contractile responses to carbachol were measured in group 1-before, group 2-at 3 ml. of urinary retention, group 3-at 3 ml. of urinary retention exposed for 30 minutes and group 4-30 minutes after catheterization. Moreover, in vivo real-time monitoring of blood flow and vesical pressure were measured in the bladders with a laser Doppler flowmeter and cystometrography, respectively. Malonaldehyde and 4-hydroxyalkenals were measured by colorimetric assay in these groups. RESULTS: In functional studies the mean maximum contractile response value plus or minus standard deviation of carbachol-to-bladder in groups 1 to 4 was 11.8 +/- 1.3, 11.9 +/- 1.7, 9.8 +/- 0.8 and 6.9 +/- 0.7 gm./mm.2, respectively. In real-time monitoring of blood flow and vesical pressure acute urinary retention significantly decreased blood flow and increased vesical pressure, and subsequent catheterization increased blood flow and decreased vesical pressure in the bladders. The concentrations of malonaldehyde and 4-hydroxyalkenals in the bladders in group 4 were significantly higher than in the other groups. CONCLUSIONS: Our data indicate that bladder dysfunction after catheterization is partially caused by free radicals, which have an important role in bladder dysfunction during acute urinary retention.

Acute Disease↗

PubMedDate not supplied

Retentiveness of dental cements used with metallic implant components.

There is limited dental literature evaluating the retentive capabilities of luting agents when used between metal components, such as cast metal restorations cemented onto machined metal implant abutments. This study compared the retentive strengths of 5 different classes of luting agents used to cement cast noble metal alloy crowns to 8-degree machined titanium cementable implant abutments from the Straumann ITI Implant System. Sixty prefabricated 5.5-mm solid titanium implant abutments and implants were used; 30 received the standard surface preparation and the other 30 received an anodized surface preparation. Anodized implant components were used to reflect current implant marketing. Sixty castings were fabricated and randomly paired with an abutment and implant. A total of 12 castings were cemented onto the implant-abutment assemblies for each of the 5 different luting agents (zinc phosphate, resin composite, glass ionomer, resin-reinforced glass ionomer, and zinc oxide-non-eugenol). After cementation, the assemblies were stored in a humidor at room temperature prior to thermocycling for 24 hours. Each casting was pulled from its respective abutment, and the force at which bond failure occurred was recorded as retentive strength. A statistically significant difference was found between the 5 cements at P < or = .001. Of the cements used, resin composite demonstrated the highest mean retentive strength. Zinc phosphate and resin-reinforced glass-ionomer cements were the next most retentive, while glass ionomer and zinc oxide-non-eugenol cements demonstrated minimal retention. In addition, retention was not altered by the use of an anodized abutment surface.

Adhesiveness↗

PubMedDate not supplied

Effect of seating force, margin design, and cement on marginal seal and retention of complete metal crowns.

PURPOSE: The purpose of this study was to determine the marginal discrepancy and retention of silver-palladium crowns cemented with zinc phosphate (Phosphacap) and glass-ionomer cement (Fuji Cap 1) using different seating forces on preparations with various margin designs. MATERIALS AND METHODS: Crown preparations with three finish lines--chamfer, shoulder, and shoulder with a 45-degree bevel--were sequentially prepared on a dentoform premolar. A metal die for each of the three finish lines was constructed. Complete metal crowns were fabricated for each metal die using a silver-palladium alloy. Three different seating forces--25, 100, and 300 N--were used to load the crowns until initial set of the cement. The marginal discrepancy was calculated by measuring the change in crown height before and after cementation using a digimatic indicator. Retention was determined by measuring the tensile strength using the Lloyd universal testing machine. RESULTS: The higher seating forces produced better crown seating but had no significant effect on crown retention. The shoulder and shoulder with bevel finish lines provided better crown retention than the chamfer. Glass-ionomer cement provided greater crown retention than zinc phosphate cement. No significant correlation between marginal seating and crown retention was revealed using a Pearson analysis. CONCLUSION: Marginal seal was not influenced by either margin design or type of luting cement, but was improved with higher seating force. Crown retention was affected by the margin finish line and the luting agent.

Analysis of Variance↗

PubMed2001

The influence of surface configuration on the retention of posts designed for use with a cast-on technique.

OBJECTIVES: The combination of an individually cast core and a prefabricated metal post is one of the many techniques to restore endodontically treated teeth. The surface characteristics of commercially available posts vary considerably and likely influence retention. In this study, the surface configuration of 11 castable prefabricated post systems and their retention at the post-cement interface were investigated. METHOD AND MATERIALS: Scanning electron microscopic photos were made to assess surfaces of the posts. Etchant residues or applied surface layers were also analyzed with an electron beam microprobe. For the retention measurements, 6 posts from each system were cemented in artificial root canals with a zinc phosphate cement. Retention was measured on a universal testing machine. RESULTS: Analysis of variance and the Ryan-Einot-Gabriel-Welsch F test revealed significant differences in retention between posts; these differences were related to the microstructure of the surfaces of the posts. In general, the coarser the surfaces, the better the retention. Gold plating of the etched surface for one manufacturer resulted in less retention compared to posts of the same type and size that were not plated. CONCLUSION: The surface configuration of a post could be an important factor when selecting a prefabricated post system.

Acid Etching, Dental↗

PubMed2002

[Postoperative urinary retention].

BACKGROUND: Retention of urine is a common postoperative problem. MATERIALS AND METHODS: We present two patients with postoperative urinary retention. Current opinions on monitoring and treatment are reviewed. RESULTS: One male postoperative patient was transferred from the postanaesthesia care unit after orthopaedic surgery under spinal anaesthesia. Shortly thereafter he collapsed. Hypotension and bradycardia were treated with intravenous ephedrine and atropine. Urinary retention was suspected and the bladder catheterised for 1,000 ml urine. A follow-up examination revealed no sequelae. A female patient was operated for haemorrhoids under epidural anaesthesia. The second postoperative day she was catheterised for 1,500 ml of urine. Two years later she had an ovarian cyst removed under general anaesthesia. Postoperative urinary retention developed with bladder overdistension (volume > 1,000 ml). A follow-up examination showed rest urine of 25 to 75 ml, and a chronic bladder dysfunction. The incidence of postoperative urinary retention varies depending upon type of surgery, gender, age, and preoperative history of urinary tract dysfunction. Method of anaesthesia or postoperative pain treatment is not correlated to incidence of urinary retention, but excessive intravenous volume load during the operation is. INTERPRETATION: Postoperative urinary retention should be monitored in all patients after surgery. All patients with history of difficulties with micturition need close supervision to avoid urinary bladder overdistention.

Adult↗

PubMed2002

[The effect of acute urinary retention on serum prostate specific antigen concentration].

OBJECTIVES: To study the effect of acute urinary retention on the serum prostate-specific antigen (PSA) concentration. METHODS: Blood samples from 34 benign prostatic hyperplasia (BPH) patients with acute urinary retention were drawn immediately before suprapubic cystomy and 48 hours after relief of urinary retention. Serum PSA concentrations were measured with radioimmunoassay. RESULTS: The mean serum PSA levels of BPH patients with acute urinary retention was (24.6 +/- 16.1) micrograms/L (range from 2.6 micrograms/L to 45.8 micrograms/L). Forty-eight hours after relief of urinary retention, the mean serum PSA levels declined to (9.4 +/- 6.3) micrograms/L (range from 1.7 micrograms/L to 16.6 micrograms/L). The difference was significant (P < 0.01). CONCLUSIONS: Acute urinary retention could dramatically increase the serum PSA value of patients with BPH. After relief of the urinary retention, the patients had a great than 50% decreased of PSA values.

Acute Disease↗

PubMed2003

A comparison of the retention of tooth-colored posts.

OBJECTIVE: The aim of this in vitro study was to compare the retention of five different esthetic post systems of similar dimensions in extracted teeth using titanium posts as controls. METHOD AND MATERIALS: Sixty recently extracted single-rooted, caries-free teeth were sectioned horizontally and mounted in acrylic resin. The samples were randomly allocated into six groups of 10 for post preparation. Post space preparation was carried out according to the individual manufacturer's instructions. All posts were bonded using Panavia F. A 4-mm hollow, metal sleeve was luted over the free end of each post prior to mounting in a universal testing machine, and the forces required to dislodge the posts using a cross-head speed of 5 mm/min were recorded. RESULTS: It was found that the parallel-sided Lightposts were significantly more retentive than all of the other posts. Parapost Fibrewhite posts were more retentive than tapered Lightposts and Snowposts. There was no significant difference between the retention of stainless steel Paraposts and any of the other groups. CONCLUSIONS: Serrated parallel-sided stainless steel posts were no more retentive than either parallel-sided or tapered tooth-colored posts in this study. When all groups were considered, post dimension appeared to influence retention, with parallel-sided posts being more retentive than tapered posts.

Ceramics↗

PubMed2003

Effect of thermocycling on the retention of glass-fiber root canal posts.

OBJECTIVE: This study investigated the effects of thermocycling on the retention of glass-fiber and resin posts. METHOD AND MATERIALS: Forty premolar and canine tooth roots were embedded in acrylic blocks shaped to fit into a retention device. The roots were randomly assigned to two groups of 20 to receive either Lightposts or Luscent Anchors which were cemented into 9-mm-deep post spaces, with Panavia F resin cement. Each group was randomly divided into two equal subgroups: one for thermocycling, and the other to serve as a control. The thermocycled specimens were cycled 3,000 times between water baths at 5 degrees C and 55 degrees C, with a dwell time of 60 seconds in each. Control specimens were stored at 37 degrees C. The tensile force required to dislodge each post from its root was recorded and the data analyzed using Student's t tests. RESULTS: There were no significant differences in the forces required to cause post-retention failure between the control and thermocycled specimens. Lightposts were significantly more retentive than Luscent Anchors without thermocycling, but this distinction was not apparent in the thermocycled groups. CONCLUSION: Glass-fiber and resin posts cemented with resin cement offer acceptable levels of retention and are not susceptible to reduced retention from thermocycling. Thermocycling should be given less emphasis in tests for the retention of root canal posts cemented with resin cements.

Bicuspid↗

PubMed2000

[Prevention and release of epidural-morphine-induced urinary retention with phenoxybenzamine and neostigmine].

OBJECTIVE: To study the effects of preoperative phenoxybenzamine (o.p) on preventing epidural-morphine-induced urinary retention and effects of neostigmine on releasing it. METHODS: 80 patients who received epidural morphine to release postoperative pain were divided into 4 groups randomly and received preoperative phenoxybenzamine (group P, n = 20), neostigmine (i. m) when urinary retention happened (group N, n = 20), both drugs (group U, n = 20), and without drugs (Control, n = 20), respectively. The incidences of urinary retention and release were observed. RESULTS: No significant decrease (P > 0.05) happened after operation in the incidence of epidural-morphine-induced urinary retention both in the group P and in the group N. Neostigmine(i. m) could significantly release (P < 0.001) the epidural-morphine-induced urinary retention when phenoxybenzamine was administrated preoperatively. CONCLUSION: Preoperative phenoxybenzamine can not prevent epidural-morphine-induced urinary retention. Neostigmine can release the urinary retention only when preoperative phenoxybenzamine is used.

Adolescent↗

PubMed2003

[Circulating test and analysis of clasp retention].

OBJECTIVE: To show the trend of the retention change during the circulation of the clasp dislodging and inserting, and to discuss the proper depth of the undercut for a specific clasp. It is also a basic study for the best designing of RPD. METHODS: The Chatillon force measuring instrument was used to record the variation of the retention of Co-Cr alloy casting Akers clasp when they were dislodging from undercuts of different depths (0.25 mm, 0.50 mm, 0.75 mm) on bicuspid and molar. RESULTS: The data was analysed of Correlation and Regression by SPSS 10.0 statistic software. The variations of the retention in the circulation are obvious from the different teeth and different undercut depths. It shows an attenuation trend in circulation (P < 0.01). After 400 times dislodging, in bicuspid group, the retention of the clasp used in 0.50 mm undercut became less than the one used in 0.25 mm undercut. While the retention of the clasp used in 0.75 mm decreases most obviously, it values 0.7670 kg. In molar group, the attenuations of the retention at different depths of undercut are similar, the retentions of the clasp still rank as, from great to less, 0.75 mm, 0.50 mm and 0.25 mm, in the depth of undercut. CONCLUSION: the proper depth of the undercut for bicuspid is 0.25 mm, and 0.50 mm for molar.

Dental Clasps↗

PubMed2006

Effect of air-particle abrasion on the retention and texture of the maxillary complete denture.

PURPOSE: To examine the effect of air abrasive particles on the retention of maxillary complete dentures. METHODS: Twenty edentulous subjects, aged 48-72 years with a mean age of 62.2 years were selected. Subjects had questionable satisfaction regarding the retention of their existing maxillary complete dentures, and satisfactory denture bearing tissue with no visible undercuts. Existing dentures were tested for retention before and after air abrasion. Then, new maxillary complete dentures were constructed for them, and tested before and after partial air abrasion. Ten of the subjects continued with a new set of dentures, to test the effect of air abrasion of the entire fitting surface. A specially designed strain gauge force transducer and a strain indicator unit were used to measure forces that required dislodging the denture from its foundation. Retention force was measured before and after the fitting surface of the dentures was uniformly air-particle abraded with 50 microm aluminum oxide abrasive particles under 4 Kg/cm2 of pressure with a quick circling motion at 10-15 mm distance for 30 seconds. RESULTS: The results showed significant improvement in the mean retention forces of the new and the existing well-fitting maxillary complete dentures at all time intervals after air-particle abrasion of part and entire fitting surfaces, while the mean retention forces for the poorly fitting dentures showed only non-significant, slightly increased retention at all time intervals after the fitting surface was air-particle abraded.

Aged↗

PubMed1991

Effects of intra-core mechanical interlocks and cement type on full crown retention.

This study compared the retention of full cast crowns over cores of amalgam or a Bis-GMA composite resin when cemented with a Bis-GMA composite resin cement or a zinc phosphate cement. The surfaces of two groups of Bis-GMA composite cores were mechanically altered with a groove or dimples to provide physical retention; two other groups were either etched with 1.23% acidulated phosphate fluoride (APF) or exposed to a zinc oxide-eugenol interim luting agent before crown cementation. Control groups of unaltered composite or amalgam core served as comparison standards. The zinc phosphate cement provided significantly greater retention with the amalgam core than with any of the composite cores. The APF-treated composite cores had the least retention of any of the zinc phosphate cementations. Cementation failure over the composite cores was at the core surface. Crown retention over the control and dimpled-surface composite core with the resin cement was twice that with zinc phosphate, and significantly greater than retention of castings cemented with the resin cement over amalgam cores. Retention over amalgam cores was significantly greater with zinc phosphate cement than with the composite resin cement.

Bisphenol A-Glycidyl Methacrylate↗

PubMed1991

[Postoperative urinary retention].

In 359 patients 371 operations were performed under general or regional anesthesia, and these were followed up with regard to anesthesiological technique, postoperative course and voiding of the bladder. Patients under 15 years of age, with severe incontinence or with a bladder catheter were excluded from the study. The surgical specialties were general surgery, orthopaedics, gynecology, ENT and ophthalmology. If any patient had not urinated by 6-10 h postoperatively and was found to have a full bladder on palpation, urinary retention was diagnosed. There were 75 patients (20%) who had urinary retention, significantly fewer women than men (p less than 0.025), and men under 35 years old had significantly less retention than older men (p less than 0.0025). The anesthesiological technique is an important factor in postoperative urinary retention: spinal anesthesia with tetracaine and adrenaline caused significantly more retention than spinal anesthesia with lidocaine 5% (p less than 0.005), and more than epidural or general anesthesia (p less than 0.005). No significant difference concerning urinary retention was found regarding surgical specialty, emergency operations, morphine or adrenaline added to tetracaine for spinal anesthesia, amount of local anesthetics used for epidural anesthesia or between spinal anesthesia with lidocaine 5% and epidural anesthesia with mepivacaine. Once urinary retention is diagnosed, conservative (privacy, relaxation exercises, getting up) or medical treatment (propyphenazone + hexahydroadiphenine (Spasmocibalgin), carbamoyl choline chloride) should be given. Catheterization should be performed only as a last resort.

Adolescent↗

PubMed1985

Acquisition and retention of active avoidance behavior in previsual rats.

The ability of previsual rats to acquire and retain an active avoidance response at intervals ranging from 0 min to 48 hr was examined in five experiments. Experiments 1 and 2 demonstrated that improvement in avoidance responding over trials was a training effect. Experiments 3 and 4 demonstrated that there was no evidence of retention of the avoidance response over retention intervals ranging from 15 min to 48 hr. Testing at intervals of 0-30 min in Experiment 5 indicated that 10-day-old rats could retain the response over intervals ranging from 0-15 min, but not over a 30-min interval. However, even at the very short intervals (5-15 min), there was evidence of a retention deficit. In general, the results suggest that previsual rats have sufficient memory capabilities to acquire an active avoidance response and to retain it over a 15-min interval. However, without intervention, e.g., reactivation, a retention deficit appears almost immediately, and retention loss seems complete within 30 min. This procedure and phenomenon may prove useful in allowing an immediate assessment of variables believed to alleviate retention loss and in eliminating the influence of many extraneous variables that could alter the retention performance of developing animals.

Aging↗

PubMed1978

Deficit in postoperative learning and retention of complex tasks by septal rats.

Pre- and postoperative acquisition and retention of locomotor tasks of different complexity were investigated in septal rats. Experiment I involved acquisition and retention of a task using a four-unit-quadruple-choice apparatus. Severe impairment in both postoperative acquisition and postoperative retention was observed from all parameters of learning: trials, errors, repetitive errors and vicarious responses. However, there were significant savings in postoperative retention, scores compared to postoperative acquisition by septal rats. Experiment II examined acquisition and retention of a less complex task by using a two-unit-quadruple-choice apparatus. Impairment of postoperative acquisition in septal rats was reflected only in the number of trials to learning criterion and vicarious responses, while the number of errors and repetitive errors were not distinguished between normal and septal animals. Retention deficits in the septal rats were reflected in all learning parameters, although there were savings in postoperative retention compared to postoperative acquisition scores attained by septal rats. It is suggested that lesions of the septal area in rats may change the integration of intero- and exteroceptive cues, providing a source of interference if the task can be solved by the use of more than one strategy.

Animals↗

PubMedDate not supplied

Comparison of retention and release periods for implant overdenture attachments.

The aim of this study was to compare the retention and release periods of the Nobel Biocare bar and clip (NBC), Nobel Biocare ball (NB), Zest anchor (ZA), Zest magnet (ZM), and Sterngold ERA (SE) attachments on an implant-retained overdenture model. The attachments were tested using two permanently placed Brånemark implants on a test model that was attached to an Instron machine (cross-head speed 50.8 mm/minute). Each attachment had one part embedded in a denture-like housing, and the other part screwed into the implants. Dislodging tensile forces were applied to the housings in two directions simulating function: vertical and oblique. Eight tests were done in two directions with three samples of each attachment. The dislodging forces generated measurements of the peak load, break load, and displacement at peak load and break load. Release periods were calculated using displacements between the peak load and break load and the cross-head speed. Results showed the NBC to be significantly most retentive for the break load when subjected to vertical and oblique forces with mean values and standard deviations of 2104.5 +/- 506.7 g and 1958.1 +/- 165.4 g, respectively. Next most retentive was the SE, followed by the ZA and NB. The ZM was significantly least retentive (127.8 +/- 7.0 g and 143.5 +/- 19.7 g). For the release period, results showed the NBC to have significantly the fastest release period for vertical and oblique forces (1.86 x 10(-3) and 7.35 x 10(-4) minutes). The ZM significantly had the slowest release period for those forces (3.02 x 10(-2) and 2.35 x 10(-2) minutes). The data suggested that the NBC could be selected when a higher degree of retention and fast release period are desired. The next most retentive was the SE; ZM was the least retentive and had the slowest release period.

Dental Abutments↗

PubMedDate not supplied

The effect of recementation on crown retention.

PURPOSE: The object of this study was to evaluate retention of complete cast crowns cemented with different luting cements and to determine whether recemented castings are as retentive as when initially placed. MATERIALS AND METHODS: Thirty standardized Rexillium III complete crowns were made on extracted human molar teeth prepared with a modified milling machine using conventional laboratory techniques. The crowns were randomly assigned into three groups according to the luting cement used: zinc phosphate (Fleck's, Mizzy), adhesive resin (Panavia-EX, J. Morita), and glassionomer (Ketac-Cem, Aplicap, ESPE-Premier Sales). Retention was evaluated by measuring the tensile force required to dislodge the crowns from tooth preparations with an Instron testing machine after thermocycling (1,500 cycles between 5 degrees C and 55 degrees C with 1-minute dwell times). Subsequently, the tooth preparations were scraped clean and polished with flour of pumice (prophylaxis paste), and the fitting surfaces of the artificial crowns were ultrasonically cleaned and air abraded using 50-micron aluminum oxide powder prior to recementation. Results were subjected to two-way analysis of variance and Tukey's Studentized Range test. RESULTS: The analysis showed the highest mean retention for cast crowns cemented with Panavia-EX cement (314 N), but the difference was not statistically significantly different from crowns cemented with glass-ionomer cement (307 N). However, crowns cemented with zinc phosphate cement (233 N) had significantly lower values (P < 0.05). Restorations recemented with zinc phosphate had significantly lower retention (190 N) than their initial cementation (P < 0.05). CONCLUSIONS: Panavia-EX and glass-ionomer cements yielded the highest initial and recementation retentive strength, with values almost 32% higher than those obtained with zinc phosphate cement during the initial cementation and 59% higher than zinc phosphate for recementation. Zinc phosphate cement exhibited significantly lower retention for the initial and second trial of cementation.

Analysis of Variance↗