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Results for “Post and Core Technique”

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PubMedDate not supplied

A structured analysis of in vitro failure loads and failure modes of fiber, metal, and ceramic post-and-core systems.

PURPOSE: This study sought to aggregate literature data on in vitro failure loads and failure modes of prefabricated fiber-reinforced composite (FRC) post systems and to compare them to those of prefabricated metal, custom-cast, and ceramic post systems. MATERIALS AND METHODS: The literature was searched using MEDLINE from 1984 to 2003 for dental articles in English. Keywords used were (post or core or buildup or dowel) and (teeth or tooth). Additional inclusion/exclusion steps were conducted, each step by two independent readers: (1) Abstracts describing post-and-core techniques to reconstruct endodontically treated teeth and their mechanical and physical characteristics were included (descriptive studies or reviews were excluded); (2) articles that included FRC post systems were selected; (3) in vitro studies, single-rooted human teeth, prefabricated FRC posts, and composite as the core material were the selection criteria; and (4) failure loads and modes were extracted from the selected papers, and failure modes were dichotomized (distinction was made between "favorable failures," defined as reparable failures, and "unfavorable failures,"defined as irreparable [root] fractures). RESULTS: The literature search revealed 1,984 abstracts. Included were 244, 42, and 12 articles in the first, second, and third selection steps, respectively. Custom-cast post systems showed higher failure loads than prefabricated FRC post systems, whereas ceramic showed lower failure loads. Significantly more favorable failures occurred with prefabricated FRC post systems than with prefabricated and custom-cast metal post systems. CONCLUSION: The variable "post system" had a significant effect on mean failure loads. FRC post systems more frequently showed favorable failure modes than did metal post systems.

Carbon↗
PubMed2000

Simplified technique for refabrication of cast posts and cores.

This article describes a simple procedure of recording contours of an existing cast post and core that needs to be reconstructed, using a polyvinyl siloxane material as a matrix for fabrication of a new cast post and core in a relatively short time with reduced cost. The procedure involves the use of an acrylic resin material under pressure, which minimizes void formation in the post-and-core pattern.

Dental Casting Technique↗
PubMedDate not supplied

Post and core fabrication for divergent canals with a cast post and core and a prefabricated dowel.

A post and core fabrication technique for multirooted teeth with divergent canals uses a combination cast post and core and prefabricated dowel. This method modifies and improves a previously reported method by using a nickel-silver technique post during casting to preserve the channel in the resin core pattern. Following casting, the nickel-silver post is dissolved with nitric acid. Minimal hand instrumentation with a post drill leaves a clean and accurate channel for cementation of an accessory prefabricated stainless steel or titanium post.

Dental Casting Technique↗
PubMedDate not supplied

Effect of surface conditioning techniques on the resistance of resin composite core materials on titanium posts.

OBJECTIVE: This study evaluated the resistance of various post and core materials against torsional forces on differently conditioned titanium posts. METHOD AND MATERIALS: One hundred fifty pure titanium posts (DIN 17850-Ti4/3.7065) were conditioned utilizing Silicoater Classical, Silicoater MD, Rocatec, Kevloc, and Siloc. Subsequently, three post and core materials (Adaptic, Coradent, Ti-Core) were applied to titanium posts that were previously coated with a light-cured opaquer (Dentacolor). Thirty sandblasted titanium posts were used as reference for each core material. Following thermocycling (5 degrees C to 55 degrees C, for 30 seconds or 5,000 cycles), maximum torsional forces were determined with an electronic torque movement key. RESULTS: Kruskal-Wallis, Mann-Whitney U-tests indicated significant differences between Adaptic, Coradent, Ti-Core (20.9 dNm, 18.84 dNm, and 18.62 dNm, respectively). There were no significant differences between Silicoater Classical (18.56 dNm), Silicoater MD (18.18 dNm), and Rocatec (16.95 dNm), while Siloc exhibited the highest results (20.44 dNm). Kevloc demonstrated significantly lower results (10.43 dNm) than those of other systems and the control group (14.49 dNm). CONCLUSION: Resistance of core materials against torsional forces on titanium posts increased with the use of chemical surface conditioning techniques, while the system using only acrylization did not improve the resistance in comparison to the unconditioned posts.

Acrylonitrile↗
PubMed2005

Trends in indirect dentistry: 2. post and core restorations.

Modern post preparation techniques reflect a change from what was once considered a prosthodontic procedure to one which marries endodontic principles with sound understanding of mechanical objectives. This article presents a rationale for techniques in materials selection and post-space preparation. A review of literature is presented and practical clinical guidelines are suggested when post placement is considered the treatment of choice.

Crowns↗
PubMed2000

Advances in restorative core materials.

The use of core build-up materials is likely to increase in coming years. The ease of use of direct materials, such as amalgam and composite-based core materials, will most certainly dominate product selection. The historic standard of the custom cast post-and-core technique is decreasing in the private practice of dentistry. Providing the foundation for a restoration that will endure the masticatory stresses that occur in the oral cavity for prolonged periods is a goal all conscientious dentists are pursuing. Only with a thorough understanding of the individual patient's oral conditions can an accurate assessment be made regarding material selection. Minimizing the risks associated with failure should include a knowledge of the material's properties, the forces that the core build-up must withstand, the occlusal scheme of the patient, and the final type of restoration or prosthesis to be fabricated. An extreme amount of professional judgement and past experience must be used in the absence of sound scientific validation. Unfortunately, little sound research, especially clinical research, exists to assist dentists in this area. New clinical studies in this area would be of tremendous benefit to the practicing dentists and would benefit the general public greatly.

Composite Resins↗
PubMed1977

Construction of a post and core to fit a completed restoration.

A simple technique to fabricate a post and core to fit a completed restoration is described. This technique saves the time and effort of remaking the restoration when endodontic treatment and reinforcement of the tooth are required after construction of the restoration.

Crowns↗
PubMed2002

Restoration of the endodontically treated tooth.

It has been the purpose of this article to provide a rationale for the restoration of endodontically treated teeth. Treatment recommendations have been made in the areas of post design, placement technique, cements, core materials, and definitive restorations, based on a review of the clinical and laboratory data.

Dental Prosthesis Retention↗
PubMed1998

Evaluation of the clinical performance and effectiveness of adhesively-bonded metal crowns on damaged canine teeth of working dogs over a two- to 52-month period.

In this clinical study, 41 metal full crown restorations of canine teeth were placed in 18 working dogs. Twenty-six canine teeth had severe attrition with no involvement of the pulp cavities; 15 fractured canine teeth were endodontically treated. With the exception of one tooth, at least one-third of the coronal part of each canine tooth was available for a supragingivally performed, minimal tooth crown preparation. A dental resin luting cement technique was used to bond the electrolytically etched crown (made from an alloy of cobalt-chrome-molybdenum) to the tooth. The metal crowns were slightly shorter and with a more rounded tip than the original tooth. Posts or post-and-core techniques were not used. Median follow-up period was 30 months (range 2 to 61 months), at which time 36 crowns were found to be intact and functional. Five crowns were lost; three as a result of subsequent injury and fracture of the tooth below the crown; one as a result of use of less than one-third of the coronal portion of the tooth for retention of the crown; and one as a result of an oblique fracture of the root.

Animals↗
PubMed1997

Long-term success rate of resin-bonded metal crowns on the canine teeth of working dogs.

In this clinical study, 19 full metal crown restorations of canine teeth were placed in seven working dogs. Thirteen canine teeth were severely abraded with no involvement of the pulp cavities; six fractured canine teeth were endodontically treated. At least 1/3 of the coronal part of the canine tooth was available for a supragingivally performed, minimal tooth crown preparation. An adhesive technique to bond the electrolytically etched crown (an alloy of cobalt-chrome-molybdenum) to the tooth was used. The metal crowns, slightly shorter and with a rounder tip than the original tooth, were bounded to the enamel and dentine by using a resin luting cement. Posts or post-and-core techniques were not used. Mean follow-up period was 32 months (range 24-52 months), at which stage 17 crowns were found to be intact and functional. Two crowns were lost as a result of trauma resulting in a fracture of the tooth below the crown.

Acrylic Resins↗
PubMed1998

Comparison of the fracture resistances of pulpless teeth restored with a cast post and core or carbon-fiber post with a composite core.

STATEMENT OF PROBLEM: The survival of pulpless teeth restored with a post and core system is a controversial issue. PURPOSE: This study compared the fracture resistance of 2 types of restorations: teeth restored with prefabricated carbon-fiber posts and composite cores to cast dowel-core restored teeth. MATERIAL AND METHODS: A total of 44 recently extracted sound premolars were randomly distributed into 2 equal groups: group I, restored with prefabricated carbon-fiber post and a composite core; and group II, with custom-cast type III gold alloy post and cores. The size and shape of the posts were identical in the 2 groups. All teeth were fully covered with a nonprecious cast crown. Fracture resistance was measured by applying a point force at 45 degrees to the long angle of the tooth. RESULTS: Mean fracture threshold was 103.7 +/- 53.1 kg for group I versus 202.7 +/- 125.0 kg for group II (differences significant with P = .003). In group II, however, fracture nearly always affected the tooth itself, whereas in group I, the post-core nearly always failed first. CONCLUSIONS: Significantly higher fracture thresholds were recorded for the cast post and core group. Teeth restored with cast posts typically showed fracture of the tooth, although at loads rarely occurring clinically.

Adolescent↗
PubMed1997

An experimental study of the removal of cemented dowel-retained cast cores by ultrasonic vibration.

A technique for the removal of cemented post-cores by means of ultrasonic vibration was studied clinically and histologically. The removal time was measured for 80 extracted human teeth, including 40 single-rooted teeth and 40 multiple rooted ones and then statistically analyzed. The periapical tissue reaction to the ultrasonic vibration was also examined histologically in dogs. The best result was achieved when lateral vibration was simultaneously given by 2 removal tips using 2 ultrasonic generators. There was little harmful influence on the periodontal tissue, excluding a transient reversible reaction.

Animals↗