SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Post-and-core placement using prefabricated posts and composite resin is an everyday procedure in most general practices. Such posts are easily placed, strong, relatively inexpensive and predictable. The most popular techniques and materials have been described. It is anticipated that post-and-core use will continue to increase because of the current trend to retain natural teeth into the mature years of life.
STATEMENT OF PROBLEM: Although bonding to all-ceramic restorations is desirable, there is little information on the use of resin cements containing a phosphate monomer, and the importance of different surface treatments on their adhesion to high-strength core materials. PURPOSE: This study attempted to determine the shear bond strength values between Panavia 21 resin cement (Kuraray) and an alumina core material (In-Ceram) after 3 surface treatments and the application of a silane coupling agent. MATERIAL AND METHODS: Forty-five In-Ceram cylindrical rods were fabricated and assigned to 3 groups. Group I specimens were treated with a 9.5% hydrofluoric (HF) acid, group II with a 5% HF acid, and group III were sandblasted. All specimens were coated with a silane coupling agent (Cavex Clearfil Photobond and Activator) before cementation with Panavia 21 to sandblasted nickel-chromium rods. As a control, group IV consisted of 8 porcelain (Vitadur Alpha) rods treated with a 5% HF acid and silane. All specimens were subjected to a load of 1.2 kg during cementation, then stored under water for 36 hours. A jig mounted on a Hounsfield Universal Testing machine was used at a crosshead speed of 0.5 mm/min to test the shear bond strengths. RESULTS: The results were 14.65 +/- 4.64 MPa for group I, 18.03 +/- 6.13 MPa for group II, and 22.35 +/- 5.98 MPa for group III In-Ceram specimens; and 18.05 +/- 8.46 MPa for control (group IV). CONCLUSION: The use of Panavia 21 resin cement and a silane coupling agent can achieve a successful bond between either sandblasted or 5% HF acid-etched In-Ceram core material.
This article is a review of the current technique and materials used in the restoration of endodontically treated teeth with post and core materials and procedures. It is intended to aid clinicians in making selections which are appropriate to their individual practices through the evaluation of relevant literature about the restoration of endodontically treated teeth.
Making an accurate impression of root canals prepared for cast dowel and cores can be impeded by the number of teeth involved and the working time of the impression material. These factors aside, the technique described can be used to obtain a detailed full-arch impression that precisely captures remaining tooth structure and all canal spaces. The two-stage technique involves first fitting tapered plastic sprues and making individual canal impressions. A full-arch pickup impression is then made to capture the individual canals. This simple and easily correctable procedure ensures an accurate master cast on which dowels and cores can be indirectly made.
BACKGROUND: The clinical decision as to whether an endodontically treated (ET) tooth requires a post and a crown poses a challenge to dental practitioners. The author conducted a review of the principles for the use of post and core and the newer materials such as ceramic and fiber-reinforced posts. TYPES OF STUDIES REVIEWED: Using a MEDLINE search and resulting cross-references, the author selected original research articles and previous review articles on the topic of ET teeth, as well as that of post and core. RESULTS: The author reviewed the principles for the use of posts in terms of when it is necessary to use a post, different types of posts, various post materials and designs. He also reviewed the criteria and technique for post space preparation and post cementation. Finally, he discussed the principles of core buildup, as well as options for the final restorations. CLINICAL IMPLICATIONS: The author provides a review of the principles for the use of post and core, crowns and the different materials available today to help clinicians make a clinical decision based on sound evidence.
In the recent three years, 60 posterior teeth with large defects have been restored by the author with the post-core retained full crown. The methods used in restoration included spiral-shifted post, spiral pin, light-curing resin core and amalgam core. This technique has the advantage of manipulating simply and mastering easily. All of the cases were followed up for a period of 9-19 months. The results show that loosening and dislocation of the crown and secondary decay of the teeth have not been revealed. There was one case in which the crown had caused irritation to the gingiva. The success rate of restoration is 97%. The masticatory force after restoration ranges from 15.9-26.9 kg in average which is much more than 10-23 kg in most individuals. This force may satisfy the requirement of masticatory functions. For the preservation of residual roots or crown, this method of restoration is of value both theoretically and practically.
An in vitro nondestructive fatigue test was applied to adhesive posts and cores made on endodontically treated human teeth. Five post-and-core systems were evaluated: one zircon oxide post, two titanium posts (with resinous or ceramic coating), and two resin-fiber posts. Each test specimen was intermittently loaded and thermocycled. The scanning electron microscope observation of sample sections showed that only the interfaces between restorative materials and dentin exhibited substantial deficiencies. The Komet ER (Brasseler) exhibited the greatest percentages of continuity at the coronal (83.88%) or the radicular (78.12%) dentin levels, while the Zircon experimental post presented insufficient adaptation to the radicular (21.25% continuity) and to the coronal (53.25% continuity) dentin. Seven of eight samples in the Komet group showed root fractures. The carbon-fiber post (Composipost) behaved satisfactorily (67.38% radicular continuity), in spite of the use of an older bonding agent formulation.
Explore the source record for details and available documents.
Six readily available plastic materials were evaluated for use as a log for locating the ends of die dowel pins. Seven criteria were divided into two main categories of adherence qualities of the material and useability. Cost was the third category evaluated and compared. Color and availability were also considered. Forty-two sophomore dental students accomplished 84 evaluations. Plasticine and Weatherstrip Caulking Cord were found to meet all criteria best.
Heat treatment during the burnout procedure may cause corrosion of the stainless steel post. This study was undertaken to determine whether alteration of the corrosion resistance of stainless steel posts occurs as a result of various simulated burnout procedures. Stainless steel posts were divided into five groups of five posts: group 1, control; 2, gypsum-bonded investment, bench cooled; 3, gypsum-bonded investment, quenched; 4, phosphate-bonded investment, bench cooled; and 5, phosphate-bonded investment, quenched. The posts were placed in individual containers of Ringer's solution and observed at 30, 180, and 600 days. Scanning electron microscopy, energy dispersive x-ray spectroscopy, optical emission spectroscopy, and optical microscopy were used to evaluate the posts qualitatively and quantitatively. Investment and heat treatment altered the metallic structure of stainless steel posts. Prefabricated posts submitted to simulated burnout procedures had a noticeable reduction in corrosion resistance. Direct casting to stainless steel posts is contraindicated.
This study compared the putty/wash one-step and two-step techniques for making addition silicone impressions. For each technique 15 impressions were made of a stainless steel base to which three tapered posts were attached. Stone models were made of all impressions. The results indicated that the interabutment distances increased slightly compared with the stainless steel model for both techniques, but the differences between techniques were not considered to be clinically important. The intraabutment measurements for the abutment without undercut increased, whereas abutments with undercuts decreased. These variations from the stainless steel model were also clinically insignificant.
Explore the source record for details and available documents.
The aim of this in vitro study was to evaluate the yield strengths of glass fibre-reinforced composite (FRC) posts and zirconia dioxide ceramic (ZDC) posts. Tapered glass FRC posts (DentinPost) and ZDC posts (Cerapost) of three sizes in diameter (ISO 50, 90, 110) were used for bending tests. Conventional prefabricated titanium posts of the same sizes served as control groups. The 0.2% yield strengths (R(0.2)) were tested on a universal testing machine. As zirconia posts fractured before they were yielded 0.2%, the fracture strength instead of the yield strength was recorded for these posts. One-way and two-way anova and Bonferroni-Dunn's multiple comparison tests were performed for the statistical analysis. The mean 0.2% yield strengths of the posts were 27 +/- 1 N for glass fibre-reinforced posts and 58 +/- 4 N for zirconia posts of ISO 50 (control group: 54 +/- 3 N). For ISO 90 yield strengths of 52 +/- 4 N for glass fibre-reinforced posts, 117 +/- 20 N for zirconia posts and 117 +/- 11 N for the control group were obtained. For ISO 110 mean yield strengths amounted to 73 +/- 5 N for glass fibre-reinforced posts, 166 +/- 23 N for zirconia posts and 141 +/- 12 N for the control group. Significantly higher yield strength was recorded for the zirconia and the titanium posts compared with the glass fibre-reinforced posts for the tested ISO sizes.
The purpose of this study is to investigate how differences in post shape, storage time and condition after removal affect impression accuracy with respect to dimension and shape. The following results were obtained for various elastic impression materials which were tested using a metal model with five different post shapes. 1. Alginate, polysulfide (regular type) and agar-agar showed substantial deformation due to undercut in post shape. Polysulfide (injection type) and polyether showed slight deformation due to undercut. Silicone (both condensation and addition types) showed very little deformation regardless of post shape. 2. As for elapse of time after removal, dimensions of all impressions decreased in varying degrees depending on type of materials. 3. When impressions were placed horizontally, increased deformation was observed as time elapsed with both the polysulfide and the alginate. Increased deformation was not observed with elapse of time for other impression materials. While the above results show that accurate impressions with little deformation at time of and after removal are obtainable depending on the types of materials, nothing currently available fully satisfies the demand for the type of impression materials that would slightly decrease in dimensions with no deformation for best results. This finding indicates the need to develop new impression materials to better satisfy the demand.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.