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PubMed1994

The effect of dowel lubrication on retention of resin-cemented dowels.

Threaded dowels were cemented into prepared canals of extracted human teeth by use of unfilled Bis-GMA resin cement. One half the dowels were lubricated before cementation, unscrewed partially, and reseated to original length after cement had set, to assure retrievability. There was no significant difference in mean tensile force required to dislodge the dowels cemented with or without prior lubrication. Lubrication of dowels makes them predictably and easily retrievable with no short-term effect on tensile strength of the cemented lubricated dowels. Long-term effects of the lubricant on the resin are unknown.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1993

Effect of acid etching on the flexural strength of a feldspathic porcelain and a castable glass ceramic.

This project studied the effect of altering surface topography by chemical etching on the strength of a feldspathic porcelain and castable glass ceramic. Fifty specimens of each ceramic material were subjected to five different etch times (in groups of 10). A silane coupling agent and composite resin cement were applied. Specimens were then subjected to a three-point flexural strength test. Representative specimens were examined under scanning electron microscope to elucidate more information on the effect and the depth of etch. There was no significant difference in the mean flexural strengths between the etched and nonetched groups and no significant difference between the different etching times for either material. Photomicrographs revealed dissimilar etch depths and selective dissolution of the phases. It appears that chemical etching can improve the retention of ceramic laminate veneers without significant loss of strength.

Acid Etching, Dental↗
PubMed2005

Use of an alternative pontic foundation technique for a fiber-reinforced composite fixed partial denture: a clinical report.

This article describes the treatment of a patient for whom a fiber-composite laminate dowel and core and polyethylene fiber were used as a conservative alternative to provide a dowel-and-core and fixed partial denture foundation. The treatment plan included removing the existing restoration on the maxillary right first molar, placing a fiber-reinforced resin dowel and core for retention and reinforcement of the maxillary first premolar, and fabricating a definitive restoration using polyethylene fiber to reinforce the fixed partial denture.

Acrylic Resins↗
PubMed2003

The retention of complete crowns prepared with three different tapers and luted with four different cements.

STATEMENT OF PROBLEM: The role of adhesive properties of cements on the retentive strength of crowns with different degrees of taper is not clear. PURPOSE: This study evaluated the retention of full crowns prepared with 3 different tapers and cemented with 2 conventional and 2 adhesive resin cements. MATERIAL AND METHODS: One hundred twenty sound human molar teeth were assigned randomly to 1 of 12 groups, (n=10). The groups represented the 4 cements: zinc phosphate (Fleck's), a conventional glass ionomer (Ketac-Cem); 2 adhesive resin cements (C&B Metabond and Panavia); and 3 tapers of 6-degrees, 12-degrees, and 24-degrees within each cement. Crowns were cast with a high noble alloy. The 6-degree taper was considered the control within each cement group. Retention was measured (MPa) by separating the metal crowns from the prepared teeth under tension on a universal testing machine. Analysis of variance was used to test the main effects on the retentive strength of full crowns, namely cements, tapers, and failure modes. The Fisher's multiple comparison test was used to evaluate the source of the differences. The chi(2) analyses were used to examine the relationships between failure types, cements, and tapers. All statistical tests were conducted at alpha=.05. RESULTS: There was a significant difference in the main effect cement (P<.0001) and taper (P=.0002). The mean retentive strength values of both Fleck's and Ketac-Cem were significantly lower than the mean retentive strength values of both C&B Metabond and Panavia (P<.0001). The retention of crowns prepared with 6-degree taper was not significant from the 12-degree taper (P=.0666). The difference in retention was significant between the 6-degree taper and the 24-degree taper (P<.0001) and between 12-degree taper and 24-degree taper (P=.0178). The types of failure were adhesive in the cement (65%), cohesive in the tooth (31%), and assembly failure (fracture of embedding resin) (4%). The type of failure was dependent on the degree of taper (P<.0001) and on the type of cement (P<.0042). CONCLUSION: Within the limitations of this study, the retentive values of the adhesive resins at 24-degree taper were 20% higher than the retentive values of the conventional cements at 6-degree taper. The use of resin luting agents yielded retention values that were double the values of zinc phosphate or conventional glass ionomer cement.

Analysis of Variance↗
PubMed2000

Effect of cement type on retention of a tapered post with a self-cutting double thread.

OBJECTIVES: The aim of this in vitro study was to examine the effect of varying the cement type on the retention of a prefabricated tapered titanium post with a self-cutting double thread (Perma-tex activ). METHODS: A total of 130 suitable roots from extracted human permanent teeth were selected. Post holes were prepared using the instruments supplied with the post system. One-hundred-twenty posts (medium size) were luted with one of four luting agents: a zinc-phosphate cement (Harvard), a glass-ionomer cement (Ketac Cem), a compomer luting agent (Dyract Cem), and a new capsulated composite luting system (Compolute). The cement groups were subdivided into three treatment groups with 10 posts each: group 1 (4-week water storage at 37 degrees C), group 2 (4-week water storage at 37 degrees C, 4000 cycles 5-55 degrees C), group 3 (4-week water storage at 37 degrees C, 4000 cycles 5-55 degrees C, 3 x 4 min mechanical stress: 40N vibrations). Another 10 posts inserted without cement and stored like group 1 served as a control. Retention was measured on a universal testing machine (Zwick Z050/TH3A) with a crosshead speed of 0.1cm/min. Data were analyzed using ANOVA with a Bonferroni or Tamhane adjustment for multiple comparisons (significance level alpha=0.05). RESULTS: In group 1, Dyract Cem was significantly more retentive than the other three cements and the control group (no cement). In group 2, Compolute demonstrated significantly higher retention than Harvard and Ketac Cem. In group 3, Compolute, Dyract Cem, and Ketac Cem obtained higher retentive values than Harvard without differing from one another. Within the cement groups, thermocycling (group 2) caused a significant decrease in retention compared to group 1 only for Dyract Cem. All cements except Compolute were different from group 1 after a combination of thermocycling and mechanical stress (group 3). CONCLUSIONS: The retention of the tapered post with a self-cutting double thread was significantly influenced by the cement type used.

Analysis of Variance↗
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↗
PubMedDate not supplied

Implant treatment in edentulous maxillae: a 5-year follow-up report on patients with different degrees of jaw resorption.

In a retrospective study, 150 patients with edentulous maxillae were selected for treatment with Brånemark implants. The patients were arranged into four different groups, based on jaw shape prior to implant placement. After second-stage surgery, they were provided with either fixed prostheses, removable overdentures followed by fixed prostheses after at least 1 year, or overdentures for the whole period. Patients were followed up for 5 years, with implant and prosthesis survival, annual visits, marginal bone loss, and complications recorded. Results of the study indicated that treatment outcome in edentulous maxillae might be predicted by careful presurgical evaluation of jaw shape. Five-year cumulative implant failure rates varied from 7.9% for patients considered to have enough bone to be provided with fixed prostheses immediately after second-stage surgery to 28.8% for those with severely resorbed jaws receiving an overdenture. The corresponding cumulative prosthesis failure rates were 3.0% and 18.9%, respectively. Patients provided with autogenous bone grafts compared favorably to the group presenting severely resorbed jaws and provided with overdentures, but showed a compromised result compared to the group with the least resorption. Failure of implant treatment correlated significantly with bone quality and ratio of 7-mm implants. All groups, except those treated with bone grafts, showed an average marginal bone level of 1.2 mm after 5 years, irrespective of type of prosthesis. The bone-grafted group showed a corresponding mean level of 2.3 mm after 5 years of function. Regarding clinical complications, a different pattern, mainly related to the type of prosthetic construction used, was observed between the groups. The number of visits clearly indicated that severely resorbed jaws provided with overdentures were the most demanding.

Adult↗
PubMed1994

Post removal using a thick-walled hollow tube post design.

PURPOSE: The retention of a post into the root is critical for the successful restoration of an endodontically treated tooth. A total of 80 Access Posts (Nos. 0, 1, 2, and 3) comprising eight groups were cemented in root canals with two different luting agents, Flexi-Flow cem with titanium and zinc phosphate cement. MATERIALS AND METHODS: Removal of these Access Posts was then performed with the corresponding retreatment drills. RESULTS: None of the samples for the No. 0 Access Posts were removed by extraction with the retreatment drills. None of the samples for the No. 1 Access Posts cemented with zinc phosphate were removed by extraction with the retreatment drills. All these posts were removed by hand with a hemostat, after breakage of the cement seal. 60% (group 3) and 40% (group 7) of the samples for the No. 2 Access Posts were removed by extraction with the corresponding retreatment drills. 80% (group 4) and 70% (group 8) of samples for the No. 3 Access Posts were removed by extraction with the corresponding retreatment drills. On an average removal of each Access Post Nos. 0 and 1 took between 1 and 2 minutes. On an average removal of each Access Post (Nos. 2 and 3) took between 2 and 3 minutes. CONCLUSION: No root fractures were observed for any sample with either technique. This was confirmed by visual and radiographic analysis.

Composite Resins↗
PubMed1997

Bond strengths of resin-to-metal bonding systems.

STATEMENT OF PROBLEM: Resinous materials for the veneers of fixed prostheses commonly require mechanical retention on metal substructures because there is no chemical adhesion. However, mechanical retention does not restrict creation of a marginal gap at the resin-metal interface, which can cause discoloration or detachment of resinous material. The development of a chemical resin-to-metal bonding could resolve this problem and also reduce the need for mechanical retention (pearls, wires) on metal frameworks. PURPOSE: This study evaluated six current methods with the use of various storage conditions to predict clinical efficacy. MATERIAL AND METHODS: Six resin-to-metal bonding systems were tested: Silicoater, Silicoater MD, Rocatec, OVS, Sebond, and Spectra-Link. All specimens were examined in bending tests after 24 hours of dry storage (category A), after 24 hours of water storage and thermocycling (category B), and after 2 months of water storage and thermocycling (category C). Tensional tests were completed for all bonding systems after dry storage, and microscopic examination (optical and SEM) was performed for all specimens. RESULTS AND CONCLUSIONS: This study indicated that certain systems can provide stable bonding of resin to metal substructures despite prolonged wet storage and intensive thermocycling. These systems can also be used clinically without retentive configurations on metal frameworks, resulting in better esthetics. Some bonding systems revealed progressive weakening of bond strengths, so research is needed to verify their clinical efficacy.

Dental Alloys↗
PubMed2001

The influence of ultrasound on the retention of cast posts cemented with different agents.

AIM: The aim of this study was to evaluate the influence of ultrasound during the removal of posts cemented with either zinc phosphate cement, glass ionomer cement or resin cement. METHODOLOGY: Eighty-four single-rooted teeth were prepared and after cementation of cast posts, they were randomly divided into six groups of 14. Group 1, 2 and 3 did not receive ultrasonic vibration, whilst groups 4, 5 and 6 received ultrasonic vibration for 10 min. The force necessary for post removal was determined using a universal testing machine. Results were statistically analysed using ANOVA and Tukey tests (5%). RESULTS: The application of ultrasonic vibration reduced the retention provided by zinc phosphate and glass ionomer cements by 39% and 33%, respectively. CONCLUSIONS: A statistically significant reduction in the force necessary to remove posts cemented with zinc phosphate and glass ionomer cements occurred following application of ultrasound. The application of ultrasonic vibration did not influence the retention of cast posts cemented with resin cement.

Analysis of Variance↗
PubMed2006

Clinical performance of resin-bonded composite strip crowns in primary incisors: a retrospective study.

AIM: The purpose of this study was to assess retrospectively the longevity of resin-bonded composite strip crowns placed in primary maxillary incisors. DESIGN: Records for 200 out of 387 children, aged 22-48 months, treated in a private paediatric dental practice and who presented for follow-up after at least 24 months were included in the study. The parameters recorded at baseline and/or at follow-up were: habits, the number and location of the decayed surfaces, colour, texture, and chipping of the restoration. Radiographic evaluation of the restorations, the quality of the margins, and the presence of pulpal and/or periapical pathoses were recorded. RESULTS: More than 80% of the restorations were judged to be successful at the final follow-up examination. Only the number of carious surfaces of the tooth at baseline influenced the treatment outcome. The failure rate was higher in central incisors with four affected surfaces (P = 0.005), and in lateral incisors with four carious surfaces (P = 0.0003), than in those presenting one or two carious surfaces in both central and lateral incisors (P = 0.002). CONCLUSION: The high success rate of resin-bonded composite strip crowns with a 2-year follow-up seen in this study suggests that this treatment modality is an aesthetic and satisfactory means of restoring carious primary incisors in young children. The retention rate is lower in teeth with decay in three or more surfaces, particularly in children with a high caries risk.

Child, Preschool↗
PubMedDate not supplied

The effect of resin composite pins on the retention of class IV restorations.

Standardized Class IV cavity preparations were made in 48 human incisors. They were then divided into three groups of 16 teeth each. Group 1 was prepared with no internal retentive features. Groups 2 and 3 included an internal pin channel prepared with a #330 and a #329 bur, respectively. All specimens were restored with a micro-hybrid resin-based composite restorative material and a fifth generation dentin bonding system. Specimens were loaded to failure in an Instron Universal Testing Machine perpendicular to the long axis of the teeth. There was no evidence to suggest a difference in force required to dislodge the restoration among the three groups tested (p=0.185). Resin composite pins do not increase the retention of Class IV resin composite restorations.

Acid Etching, Dental↗
PubMed1997

Mechanical properties of endodontic posts.

Twenty-two commercially available endodontic posts were examined with regard to stiffness, elastic limit and resistance to fracture. Differences in mechanical properties were explained by differences in width, shape and surface structure. In the selection of an endodontic post, its stability rather than its retention should be of primary clinical concern. Accordingly, the authors advocate the use of endodontic posts that have a cylindrical coronal portion and a conical apical portion.

Dental Alloys↗
PubMed1997

The effects of die-spacing on post-cementation crown elevation and retention.

This paper reviews the relevant dental literature concerning the effect of die-spacing on crown elevation and pre- and post-cementation crown retention. Techniques of providing die-spacing and measurement of the thickness of die-spacer are discussed. A review of the role of the provision of a cement space in reducing post-cementation crown elevation is presented. Factors which may affect crown retention prior to and following cementation are also reviewed. The influence of variables in techniques and experimental design on the results of the studies reviewed is discussed.

Cementation↗
PubMed1996

The art of crown preparation: a review of principles.

The following paper consists of a literature review related specifically to the biomechanical principles that determine the design and preparation of teeth: Retention and Resistance form. Magnitude of forces, geometry of tooth preparation, taper, stress concentration, the influence of luting agents and the clinical implication of these factors upon retention and resistance are presented and discussed from the point of view of several authors from the early 1900s until the present.

Biomechanical Phenomena↗
PubMed2006

Outcome of prosthetic joint infections treated with debridement and retention of components.

BACKGROUND: Debridement and retention of the prosthesis represents an attractive surgical modality for treatment of prosthetic joint infection, but risk factors for treatment failure require clarification. METHODS: We conducted a retrospective cohort analysis of all patients with a prosthetic joint infection who were treated with debridement and retention of the prosthesis at the Mayo Clinic (Rochester, Minnesota) between 1995 and 1999. RESULTS: Debridement and retention of the prosthesis was the initial treatment modality for 99 episodes of prosthetic joint infection that occurred in 91 patients who presented to the Mayo Clinic during 1995-1999. A total of 32% and 23% of all episodes were due to Staphylococcus aureus and coagulase-negative staphylococci, respectively. The median duration of intravenous antimicrobial therapy was 28 days (range, 1-90 days). Oral antimicrobial suppression was used in 89% of the episodes, for a median duration of 541 days (range, 5-2673 days). Treatment failure occurred in 53 episodes during a median follow-up period of 700 days (range, 1-2779 days). The 2-year survival rate free of treatment failure was 60% (95% confidence interval [CI], 50%-71%). Variables associated with an increased risk of treatment failure in multivariable analysis included the presence of a sinus tract (hazard ratio, 2.84; 95% CI, 1.48-5.44; P = .002) and a duration of symptoms prior to debridement of > or = 8 days (hazard ratio, 1.77; 95% CI, 1.02-3.07; P = .04). CONCLUSIONS: Debridement and retention of the prosthesis is a common surgical modality at our institution to treat prosthetic joint infection. Risk factors independently associated with treatment failure include the presence of a sinus tract and duration of symptoms prior to debridement of > or = 8 days.

Adult↗
PubMed1993

The fixed mandibular implant: a 6-year review.

In a review of 102 consecutive cases of the fixed mandibular implant there were no failures; all appeared clinically to be osseointegrated and functioning well. There were an unexpected number of gingival infections and instances of inflammatory gingival hyperplasia, but these have been reversible and manageable. A change in sleeve nut design has improved gingival health. The Fixed Mandibular Implant (Hall Reconstructive Systems, Carpinteria, CA) offers immediate denture stability and function, and provides the opportunity for a fixed, fixed removable, or overdenture prosthetic reconstruction.

Adult↗
PubMed2026

Influence of endodontic access on the fracture resistance, retention and microleakage of full-coverage restorations in vitro: A systematic review and meta-analysis.

BACKGROUND: Endodontic access through retained full-coverage restorations (FCRs) is a preferred option for patients because of its high cost-effectiveness. However, the clinical performance of FCRs after repaired access cavity remains insufficiently characterized. This systematic review investigates the effects of endodontic access cavity preparation through retained FCRs on fracture resistance, retention, and microleakage based on in vitro studies. METHODS: A comprehensive search was performed in PubMed, Web of Science, and Scopus databases. Studies investigating the influence of endodontic access on the fracture resistance, retention, and microleakage of FCRs were included. Two independent reviewers conducted study selection, data extraction, and risk-of-bias assessment using the QUIN tool. Meta-analysis was employed to estimate fracture resistance and retention, with sensitivity analysis and subgroup evaluation also performed. Microleakage was summarized qualitatively. RESULTS: Twentythree studies were included: fracture resistance (n = 15), retention (n = 5), and microleakage (n = 3). Endodontic access significantly reduced fracture resistance for zirconia (p = 0.0002) and lithium disilicate (LD) restorations (p = 0.007), but not for resin-matrix ceramic (RMC) restorations (p = 0.25). Abutment tooth type contributed to heterogeneity within the LD and RMC subgroups. Retention was significantly reduced when access cavities were left unrepaired (p = 0.03), whereas appropriate repair protocols restored or enhanced retention relative to baseline. Accelerated aging increased microleakage in retained FCRs. Surface pretreatments and flowable resin liners tended to reduce microleakage, but findings were inconsistent. CONCLUSIONS: Endodontic access significantly reduces fracture resistance of zirconia and LD FCRs, whereas RMC restorations show no significant change. Appropriate repair protocols can restore or improve retention, potentially exceeding original values. Limited evidence suggests that effective sealing is achievable with appropriate materials. However, well-designed and in-vivo researches are needed to provide more detailed clinical guidance. CLINICAL SIGNIFICANCE: When performing endodontic access through retained FCRs, reduced fracture resistance must be carefully considered for zirconia and LD restorations, while RMC restorations may be exempt from this concern. Loss of retention with access can be restored after repair. Surface pretreatment and flowable resin liners help decrease microleakage.

Humans↗