SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
An indirect technique to prepare a multirooted pulpless tooth to receive a crown is presented. The crown also may be made on the newly completed core and its die. The procedure promotes the use of a commercial dental laboratory. The system, which uses divergent roots, results in a cast core having maximum retention.
An indirect post and core technique in which the core is waxed and invested with the die has been described. The post and core are cast directly into the invested die, which has the advantage of an accurate casting of the post preparation obtained with less laboratory time and without the disadvantages of retrieving an intact wax pattern. This technique is particularly suited for long, narrow post preparations; short preparations where precise fit is necessary for retention; and multiple adjacent post preparations.
An in vitro study was performed evaluating three post and core techniques with and without full crown coverage on extracted mandibular molar teeth. The materials evaluated were amalgam, composite resin, and stainless steel posts, and a combination of cast-gold and stainless steel posts. The results indicate that the method of post and core technique may not be as significant as the placement of full coverage cast-gold crown restorations with sound design and placement of margins beyond the buildup restoration.
The technique described results in a well adapted cast post and core with good retention (Figs. 18 and 19). The chances of perforation of the root and trauma to the patient are reduced, and the expense of the procedure is minimal. This system is adaptable to single- or multirooted teeth and continually produces good results with minimal problems.
A practical direct technique for making post and core impressions with a T-pin and self-curing acrylic resin was described. Emphasis was placed on the function of the T-shaped plastic pin in fabricating the pattern. Clinical procedures for each step were described in detail. The unique characteristic of the T-pin of softening and becoming very sticky when exposed to direct contact with acrylic resin monomer allows soft acrylic resin to adhere to it, resulting in an accurate direct impression of the canal.
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.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
A laminated single impression technique for cast post and core has been described. Its advantages are the ease and versatility with prefabricated or customized post techniques (Fig. 14) and the one-step registration of single or multiple divergent canals. Its disadvantage is the necessity for additional laboratory procedures.
PURPOSE: This project compares an accelerated technique for the casting of post-and-core restorations with four traditional techniques. The accelerated technique uses two phosphate-bonded investments and the traditional techniques use a gypsum- and a phosphate-bonded investment. The study measures and compares the differences between the seating of the casting and the seating of the acrylic resin pattern. The effects of the techniques on the fit of castings with and without a ferrule are also compared. MATERIALS AND METHODS: Six groups of 10 castings were made from plastic patterns formed on a stainless steel test die. A different investment and/or burnout method was used for each group. Each group had two subgroups: ferruled and nonferruled. The fit of the plastic patterns was measured at two time intervals after forming, 2 weeks and 3 months. The patterns were invested immediately after the 3-month measurement, and the difference in fit of the castings was calculated. An ANOVA and Tuckey-Kramer test were done to determine the statistical validity. RESULTS: The seating of the patterns after 3 months of storage was consistently worse than the 2-week measurements of fit. The ferrule and nonferrule patterns were not statistically different in seating. Measurement of the castings showed that the ferruled castings seated significantly worse than the nonferrule castings. The difference in the seating of the castings as compared with the patterns was considered clinically unacceptable, showing a range of 0.301 mm to 0.528 mm. The nonferrule castings showed a significant difference in seating among groups. The difference ranged from -0.099 mm to 0.322 mm. CONCLUSIONS: The castings of the ferrule subgroups were considered clinically unacceptable and were not analyzed for significance. Among the nonferrule castings, the group using a gypsum investment and conventional technique for investing and burnout but no ring liner showed the best seating. The accelerated technique was intermediate in seating with a difference of 0.148 mm from the seating of the patterns. This group was significantly different from the two best groups but not from the remaining three groups.
Explore the source record for details and available documents.
Casting a core to a prefit post reduces the need for adjustments at cementation. This study compared two-piece post and core castings to one-piece castings of the same geometric configuration. The specimens were made with 0.070-inch Whaledent laboratory burnout posts invested in a phosphate investment and cast with Midas, Sturdicast, or Rexillium III alloys. Three groups (n = 10) with two-piece castings had the post cast followed by a second casting of a 1 mm thick core to the post head. Three groups (n = 5) were cast in one piece. The specimens were tested for tension at a head speed of 1 cm/min. One Midas alloy two-piece casting was dislodged at the post head-to-core interface whereas the other specimens failed within the post. There was no significant difference between the two techniques using a generalized linear model (p less than 0.05).
An accelerated technique for casting a direct-pattern post and core restoration is presented. The entire clinical and laboratory procedure may be completed within 1 hour. The necessity for two appointments for completion of the restoration as well as the necessity of making two provisional restorations may be eliminated.
Carbon fibre reinforced carbon (CFRC) in the form of a prefabricated post has recently been developed and is theoretically acceptable for consideration in an endodontic post-retained crown system. This study compared four different types of postcore system cemented into 40 extracted anterior human teeth. The test groups consisted of CFRC posts cemented with a composite resin luting agent, and used with either a cast gold alloy core (Group B) or a composite resin core (Group C). Two existing post-core techniques were used as controls for comparison with the CFRC groups. One control was a prefabricated wrought precious alloy post having a cast gold alloy core, and cemented with zinc phosphate cement (Group A). The other was a prefabricated stainless steel post with a composite resin core, and cemented with a composite resin luting agent (Group D). All specimens were restored with a gold alloy crown and tested to failure with an obliquely applied compressive load at 130 degrees in an Instron using a cross-head speed of 5 cm min-1. The results showed that post-retained crowns using a prefabricated CFRC post exhibited properties comparable with, and in some cases better than, those of existing prefabricated posts. The mode of failure of specimens restored with a CFRC post was more favourable to the remaining tooth tissue than was that of specimens restored with a metallic post.
A technique to make a post and core pattern that can be used to save an existing crown has been presented. The technique should become an additional tool in the treatment armamentarium.
A method of removal of a post cemented to crown with the recovery of the undamaged crown has been presented. The fabrication of a replacement post-core assembly and the reuse of the original crown is described.