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PubMed2002

Retention strengths of five luting cements on prefabricated dowels after root canal obturation with a zinc oxide/eugenol sealer: 1. Dowel space preparation/cementation at one week after obturation.

PURPOSE: This investigation examined the effect of 5 different cements on the retention strength of prefabricated endodontic dowels placed into root canals previously obturated with gutta percha and a zinc oxide/eugenol (ZOE) sealer. MATERIALS AND METHODS: Ninety-six single-rooted teeth were decoronated, filed, cleaned, sequentially shaped, and divided into 6 groups of 16 specimens each. Five of the groups were then obturated with gutta percha and a ZOE sealer. One group was not obturated and served as the control group. Dowel space preparation and dowel cementation for all groups were completed 1 week later. Ten-mm deep dowel spaces were prepared using size 6 Gates Glidden drills. Size 5 Paraposts were then cemented with 5 different cements: Panavia 21 for group 1 (unobturated controls) and group 2; Ketac-Cem glass ionomer for group 3; Fleck's zinc phosphate for group 4; Parapost (composite) Cement for group 5; and C&B Metabond 4-META for group 6. After 48 hours, the dowels were removed using a universal testing machine in tensile mode at 1 mm min(-1). RESULTS: The following results were found (all values in kg): group 1 (controls; Panavia 21) mean = 61.81, 95% CI = +/-8.65; group 2 (Panavia 21), mean=43.15, 95% CI = +/-7.81; group 3 (Ketac-Cem), mean =34.45, 95% CI = +/-4.93; group 4 (zinc phosphate), mean = 25.07, 95% CI = +/-5.03; group 5 (Parapost Cement), mean = 24.99, 95% CI = +/-5.35. None of the group 6 (C&B Metabond) specimens developed measurable bond strengths, so this group was excluded from parametric statistical analyses. An analysis of variance (ANOVA) showed a significant effect of group; pairwise multiple comparison procedures (Tukey test) showed that group 1 (controls) had significantly greater retention than all other groups (p <0.001); group 2 (Panavia 21) had significantly greater retention than groups 4 (zinc phosphate) and 5 (Parapost cement) (p <0.001). None of the other pairwise comparisons were statistically different. CONCLUSION: Paraposts cemented with Panavia 21 in unobturated root canals exhibited significantly higher retention than Paraposts luted with Panavia 21 and 4 different cements into dowel spaces prepared 1 week after obturation with gutta percha/ZOE sealer (p <0.001). Among the obturated groups, Panavia 21 cement (group 2) demonstrated significantly greater retention of Paraposts than zinc phosphate (group 4) and Parapost composite (group 5) cements (p <0.001). Ketac-Cem glass ionomer cement (group 3) had intermediate retention values that were not statistically different than those of groups 2, 4, and 5 (p >0.05). The 4-META cement, C&B Metabond, failed to polymerize.

Analysis of Variance↗
PubMed1996

Factors influencing retention of a CeraOne gold cylinder.

Missing single teeth may be replaced using an endosseous dental implant. The CeraOne system uses a gold alloy cylinder that is cemented to a titanium abutment. This study evaluated the effect of three variables on cement failure loads required to unseat a gold alloy cylinder from its abutment. Two chimney heights (commercially available 3.7 mm and custom fabricated 5.0mm), three luting agents (zinc phosphate, Tempbond NE, and Tempbond), and two luting volumes (0.01 mL and 0.02 mL) were tested. A mechanical testing instrument was used to exert a uniaxial tensile force on the gold cylinders 2 hours after cementation. An analysis of variance and Tukey post hoc test demonstrated that both the choice of luting agent and chimney height affected cement failure loads (P <0.0001). An interactive effect between luting agent and chimney height was observed, with the combination of zinc phosphate and a 5.0 mm abutment-gold alloy cylinder complex resulting in significantly greater retention (P<0.0001). The use of 0.01 mL or 0.02 mL of luting agent resulted in comparable retention values. The results indicate that both chimney height and choice of luting agent may affect retention of a CeraOne gold alloy cylinder. The use of 0.01 mL of luting agent is recommended to minimize expression of excess cement at the restoration-abutment interface.

Analysis of Variance↗
PubMed1992

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

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

Analysis of Variance↗
PubMed2006

Effect of eugenol-based endodontic cement on the adhesion of intraradicular posts.

The present study evaluated, in vitro, the influence of an eugenol-based endodontic sealer (EndoFill) on the adhesion of intra-radicular posts cemented with a resin-based cement (Enforce) ou a zinc phosphate cement. Twenty-four single-rooted maxillary canines were divided into 2 groups (n=12) and obturated with either gutta-percha points plus EndoFill or gutta-percha points alone (no cement). In each group, half of intracanal posts (n=6) were cemented with Enforce resin-based cement and half with zinc phosphate cement. Specimens were submitted to pull-out test in an Instron machine and tensile force was applied at a crosshead speed of 0.5 mm/min until post dislodgement. The maximum forces required for post removal was recorded (N) and means were submitted to statistical analysis by Kruskal-Wallis test (p<0.01). Posts cemented with zinc phosphate cement were significantly more retentive (353.4 N) than those cemented with Enforce (134.9 N) (p<0.01). Regarding the influence of the eugenol-based cement (EndoFill) on post retention, there was statistically significant difference (p<0.01) only between the groups cemented with Enforce, i.e., in the canals filled with EndoFill + guta-percha there was lower bond strength than in the canals filled with gutta-percha points alone (101.5 and 168.2 N, respectively). In conclusion, the zinc-phosphate-based cement showed greater post retention than the resin-based cement. The findings of this study suggest that the eugenol-containing sealer interfered with the adhesive properties of the resin-based cement.

Dental Cements↗
PubMed2001

Assessment of clinical preparations for single gold and ceramometal crowns.

OBJECTIVE: Single-crown preparations at a dental teaching hospital were compared with guidelines advocated in the dental literature. METHOD AND MATERIALS: Sixty-three single complete gold crown and 151 single ceramometal crown preparations were evaluated. Impression silhouettes were measured for occlusal and axial wall tooth reductions, shoulder widths, internal shoulder angles, and axial wall convergence angles. Marginal designs, the presence of retention grooves and undercuts, and the types of cores present were also recorded. RESULTS: Cuspal reduction was generally inadequate for the ceramometal crowns, and central fossa reduction was insufficient for both complete gold crowns and ceramometal crowns. The facial shoulder widths were also generally underprepared for the ceramometal crowns. Axial wall convergence angles for both complete gold crowns and ceramometal crowns were generally much greater than recommended. Large faciolingual convergence angles for anterior ceramometal crowns were associated with the absence of cingulum walls. Few preparations had retention grooves or undercut areas. CONCLUSION: Although strict guidelines for tooth preparations for complete crowns are available and well known to dentists, the preparations in this study did not always conform to these recommendations.

Analysis of Variance↗
PubMed2006

Composite resin root coping with a keeper for magnetic attachment for replacing the missing coronal portion of a removable partial denture abutment.

Numerous methods for replacing missing removable partial denture abutments have been introduced, however, most of them are time consuming and require several visits to complete the procedure. Since magnetic attachments can provide support and bracing as well as retention for overdenture abutments, the remaining tooth root structure can be used to support the coping with the keeper. Through the use of composite resin and adhesive material, improved retention of the keeper to the root may be achieved, along with improved esthetics. This article describes a method for replacing the missing abutment of a removable partial denture with a magnetic attachment, and a composite resin coping with a keeper.

Composite Resins↗
PubMed2001

Aesthetic and adhesive cementation for contemporary porcelain crowns.

The evolution of aesthetic restorative materials has led to the development of new preparation designs and cementation protocols. While conventional cements were able to provide mechanical and macromechanical retention for restorations with limited aesthetic expectations, resin cements with micromechanical retention have been formulated as aesthetic alternatives. The objective of the present article is to establish the differences between conventional and adhesive crown cementation techniques, as well as to provide guidelines for reducing postoperative sensitivity and improving aesthetic and functional results.

Cementation↗
PubMedDate not supplied

Rigidity and retention of ceramic root canal posts.

Ceramic root-canal posts offer potential advantages over other types with respect to aesthetics and biocompatibility. Any post must be sufficiently rigid and retentive to withstand functional forces. Ceraposts (1.2 mm coronal diameter, ceramic, tapering, smooth posts) and Paraposts (1.25 mm, stainless-steel, parallel, serrated posts) were tested for rigidity by means of a three-point bending test. To test retention in roots, ceramic posts were cemented using one of three protocols: (1) glass-ionomer cement, (2) silane coupling agent and resin cement, or (3) sandblasted post surface, silane coupling agent, and resin cement. Stainless-steel posts were cemented with resin. The tensile force required to dislodge the posts, following four weeks of storage in water, was recorded. Data were compared using Student's t-test and Mann-Whitney U analysis. Ceraposts were significantly more rigid than Paraposts (p < 0.001). Paraposts cemented with resin were significantly more strongly retained than Ceraposts following any cementation protocol (p < 0.001). Retention of the ceramic posts was significantly greater with a silane coupling agent and resin cement than with glass-ionomer cement (p < 0.001). Sandblasting the ceramic posts produced variable results and needs further investigation before it could be recommended.

Acid Etching, Dental↗
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↗
PubMed1997

Effect of different surface textures on retentive strength of tapered posts.

STATEMENT OF PROBLEM: Tapered posts allow for the preservation of tooth substance in the fragile apical area and are advantageous in clinical situations where they conform to the root and canal configuration of endodontically treated teeth. However, their lower retention compared with passive parallel-sided or active threaded posts is a disadvantage. PURPOSE: This study determined the retentive strength of tapered titanium posts with different surface textures and examined the effect of roughening dentinal walls of the prepared post space. MATERIAL AND METHODS: Posts with four surface configurations (smooth, with and without grooves, and sandblasted, with and without grooves) were examined when cemented in extracted anterior teeth. RESULTS: The smooth post showed the lowest retentive strength. Sandblasting the smooth post more than doubled its retentive strength. The retentive strength of both smooth and sandblasted posts could be further increased by the addition of circumferential grooves. Roughening the dentinal walls of the prepared post space increased the retentive strength of sandblasted posts with and without grooves even more. CONCLUSIONS: These findings indicated that, when a tapered post is used, roughening the dentin canal wall, as well as sandblasting and grooving the post, can provide statistically significant additional resistance to dislodgment.

Analysis of Variance↗
PubMed1998

Retention of parallel-sided titanium posts cemented with six luting agents: an in vitro study.

PURPOSE: This in vitro study compared the effectiveness of 6 luting systems on the retention of prefabricated titanium posts. MATERIAL AND METHODS: A total of 120 single-rooted teeth were sectioned at the cementoenamel junction and treated endodontically. Roots were mounted in copper cylinders, and prefabricated, parallel-sided titanium posts were cemented according to the manufacturer's instructions. Two resin-ionomer hybrid cements and 2 resin cements were tested with corresponding dentin bonding agents. A glass ionomer cement was also tested, and zinc-phosphate cement served as the control. Samples were tested in an Instron universal testing machine to catastrophic tensile failure. RESULTS: Advance cement with Prime and Bond systems was found to be statistically more retentive than all other groups tested (P < .05). Cement It with Bond It and Permalute with Permalute Primers A and B systems demonstrated significantly greater retention than Ketac Cem cement, Resinomer with One-Step system and zinc-phosphate cement (P < .05). There was no statistically significant difference among Ketac Cem cement, Resinomer with One-Step system, and zinc-phosphate cement.

Analysis of Variance↗
PubMedDate not supplied

Guidelines for using posts in the restoration of endodontically treated teeth.

A review of the literature was done to determine when posts are required for restoring endodontically treated teeth and to give guidance on preparation of post space, design of posts, and use of luting agents. Posts were deemed to be unnecessary when adequate coronal tooth structure was present to retain a core. It was found that tooth structure should not be removed to construct a stronger post. The thinnest post with adequate strength was recommended. For best retention, it was found that post surfaces should not be smooth. When resin reinforced glass ionomer cements were used, they were found to be potentially harmful to restored teeth. Remaining coronal tooth structure was found to have the highest correlation in regard to success of the final restoration of endodontically treated teeth.

Cementation↗
PubMed2004

Efficiency considerations for the purely tapered interference fit (TIF) abutments used in dental implants.

A tapered interference fit provides a mechanically reliable retention mechanism for the implant-abutment interface in a dental implant. Understanding the mechanical properties of the tapered interface with or without a screw at the bottom has been the subject of a considerable amount of studies involving experiments and finite element (FE) analysis. In this paper, approximate closed-form formulas are developed to analyze the mechanics of a tapered interference fit. In particular, the insertion force, the efficiency, defined as the ratio of the pull-out force to insertion force, and the critical insertion depth, which causes the onset of plastic deformation, are analyzed. It is shown that the insertion force is a function of the taper angle, the contact length, the inner and outer radii of the implant, the static and the kinetic coefficients of friction, and the elastic modulii of the implant/abutment materials. The efficiency of the tapered interference fit, which is defined as the ratio of the pull-out force to insertion force, is found to be greater than one, for taper angles that are less than 6 deg when the friction coefficient is 0.3. A safe range of insertion forces has been shown to exist. The lower end of this range depends on the maximum pull-out force that may occur due to occlusion in the multiple tooth restorations and the efficiency of the system; and the upper end of this range depends on the plastic deformation of the abutment and the implant due to interference fit. It has been shown that using a small taper angle and a long contact length widens the safe range of insertion forces.

Animals↗
PubMedDate not supplied

A 10-year longitudinal study of fixed prosthodontics: clinical characteristics and outcome of single-unit metal-ceramic crowns.

PURPOSE: The purpose of this study was to report on the clinical characteristics and outcome of 688 single-unit metal-ceramic crowns placed in a specialist prosthodontic practice between January 1984 and December 1992. MATERIALS AND METHODS: Clinical and laboratory techniques were standardized and patients were recalled by the author between June and December of 1993. The outcome of all crowns was allocated to one of 6 fields in this assessment period. RESULTS: Clinical review examination by the author covered 87% of the crowns. Of these, 52% had been in service for 5 to 10 years and 48% for less than 5 years but more than 1 year; 67% of the crowns were placed on vital teeth and 94% were given a "good prognosis" rating at examination. The repair and failure rates of crowns in the 5 to 10 years in clinical service group were both 3%. Crowns on nonvital teeth in the same grouping had a significantly greater failure rate (5%) than crowns on vital teeth (1%), and anterior teeth had a significantly greater retreatment rate than posterior teeth. Retreatment for all 25 crowns occurred within 66 months after cementation. Tooth fracture accounted for 56% of retreatments, while caries and loss of retention accounted for only 24% of retreatments; 2% of initially vital teeth were endodontically treated during the survey period. CONCLUSION: Single-unit metal-ceramic crowns have a high expectancy of exceeding 10 years of clinical service when the described clinical and laboratory protocol is applied.

Adult↗
PubMedDate not supplied

Comparison of the retention of 5 core materials supported by a dental post.

PURPOSE: This study evaluated the retention of dental post heads (No. 2 Flexi-Post) embedded in 5 core materials (1 automix resin composite, 2 hand-mixed resin composites, and 2 glass ionomers). MATERIALS AND METHODS: Samples were prepared by embedding post heads in 4.5-mm-thick disks of core material. RESULTS: The resin composite materials provided significantly more retention than the glass-ionomer-based materials. The post head retention of the automix resin composite was comparable to that of the hand-mixed resin composites. CONCLUSION: Unlike the resin composite samples, all the glass-ionomer samples fractured during testing. This is an unacceptable condition for a clinically successful restoration.

Analysis of Variance↗
PubMedDate not supplied

Retention, marginal leakage, and cement solubility of provisional crowns cemented with temporary cement containing stannous fluoride.

PURPOSE: This in vitro study investigated the (1) retention and microleakage of provisional crowns cemented with temporary cements to which stannous fluoride (SnF2) was added, and (2) solubility of these cements. MATERIALS AND METHODS: Provisional crowns were constructed of acrylic resin with shoulder preparations for 12 molars. The crowns were luted with Tempbond, Tempbond NE, and Freegenol temporary cements, and also with SnF2 added to these cements. Specimens were thermocycled 100 times, stored for 6 days, and immersed in 0.5% basic fuschin. Seven days after cementation, crown removal (retention) tests were conducted. Marginal leakage was assessed using a five-level scale to score dye penetration. Solubility in water of the cements with and without SnF2 was assessed using cement disks. RESULTS: Freegenol was more retentive than the other cements. The incorporation of SnF2 significantly increased the retention capacity of Freegenol and Tempbond NE but had no effect on Tempbond. Tempbond showed significantly higher dye penetration than Freegenol. The addition of SnF2 did not alter the dye penetration of the cements. There were no significant differences in the solubility of the cements. However, the incorporation of SnF2 increased the solubility of Freegenol and Tempbond NE (P < .001) and Tempbond (P < .01). CONCLUSION: The addition of SnF2 increased the retention of temporary crowns cemented with Tempbond NE and Freegenol but did not affect the retention of those cemented with Tempbond. The marginal leakage of crowns cemented with the tested temporary cements with and without the incorporation of SnF2 was similar. However, the addition of SnF2 increased the solubility of the cements.

Acrylic Resins↗
PubMed2003

Factors determining post selection: a literature review.

Most endodontically treated teeth require a post-and-core build-up for restoring the teeth to optimum health and function. Selection of an appropriate post-and-core system from the wide variety of those available may be a clinical dilemma. Therefore, the purpose of this article is to review the literature to identify the various factors that influence the selection of the post-and-core assembly. English-language peer-reviewed articles between 1961 and 2002 were identified using MEDLINE, as well as a hand search. The following key words were used: post, design, retention, fracture resistance, survivability, and esthetics. Selection of a post and core system should satisfy many interrelated biologic, mechanical, and esthetic factors to optimally restore the endodontically treated tooth to adequate form and function. This review may serve as a guide to aid the clinician in the selection of a post-and-core system.

Dental Prosthesis Design↗
PubMedDate not supplied

Post and core retention with different cements.

In this study, bond strengths of four cement systems--Comspan resin composite luting cement with and without Gluma dentin bond, Fleck's zinc phosphate cement, and Ketac-Cem glass ionomer--used in cementing cast post-cores were investigated. Gluma appears to enhance the bond at the post/tooth interface, resulting in decreased variability and increased strength.

Analysis of Variance↗