Four Post-and-Core Combinations as Abutments Stefan Ellner, LDSa for Fixed Single Crowns: Tom Bergendal, LDS, PhDb A Prospective up to 10-Year Study Bo Bergman, LDS, PhDc Purpose: In the present prospective study, four different post-and-core systems were evaluated over a period of up to 10 years. Materials and Methods: Fifty endodontically treated teeth in 31 patients were randomized to one of four groups for post-and-core placement: Group 1 received conventional tapered cast posts and cores (n = 14); group 2 received ParaPost system prefabricated gold posts with cast cores (n = 13); group 3 received ParaPost system cast posts and cores (n = 13); and group 4 received Radix-Anchor posts (n = 10). Clinical and radiologic evaluations were made. Results: One post and core in group 2 was functioning well 58 months after placement when the patient died. No posts and cores in groups 1 or 2 had been lost or had any complications, one in group 3 had been lost because of a root fracture after 108 months, and two in group 4 had been lost after 54 and 88 months, respectively, because of loss of retention. The final treatment result for 46 of the 49 remaining posts (30 patients) was successful. The overall failure rate was 6%. There were no statistically significant differences between the four groups. Conclusion: If recommended procedures are strictly followed, posts and cores can serve as abutments for fixed single crowns with satisfactory long-term results. Int J Prosthodont 2003;16:249–254. number of prefabricated and individually de- light-curing resins, and one used cast-metal posts Asigned posts have been developed and, in gen- and cores. Of 154 restorations, 11% failed. The au- eral, marketed with no presentation of any evidence thors found no statistically significant differences be- of their superiority or inferiority in relation to other tween the three techniques and concluded that ex- systems. To evaluate the different posts, numerous in tended periods of clinical investigation are needed to vitro studies have been performed.1 However, in determine which systems will have the best clinical vitro studies often produce conflicting results and results in the long term. thus are of little help in deciding which post-and-core The present prospective clinical study was de- system would be best in a given clinical situation. signed to evaluate the clinical outcome of four dif- In contrast with the numerous in vitro studies, ferent post-and-core combinations in a longitudinal comparatively few clinical studies have been pub- perspective. The hypothesis was that the four com- lished. Most are retrospective,2–17 but to the best of binations are comparable, provided that a 2-mm fer- the authors’ knowledge, only one prospective study rule is prepared on the tooth. has been published.18 That 3-year study compared three techniques; two used prefabricated screw posts Materials and Methods or ParaPost stainless steel posts (Whaledent) with Fifty endodontically treated teeth in 31 patients (14 aSenior Consultant and Head, Clinic for Prosthodontics, Specialist women and 17 men aged 16 to 75 years, mean age Dental Care Center, Kalmar County, Sweden. 48 years) met the inclusion criteria. All patients gave bHead, Department of Prosthetic Dentistry, Institute for Post- their written informed consent to participate in the graduate Dental Education, Jönköping, Sweden. study. The patients were randomized to a certain cProfessor Emeritus and Former Chair, Department of Prosthetic Dentistry, Medical-Odontological Faculty, Umeå University, Sweden. type of post-and-core combination by lot. Initial prosthodontic treatment was performed between Reprint requests: Dr Stefan Ellner, PO Box 299, SE-391 23 Kalmar, September 1989 and September 1993. Sweden. Fax: + 46 480 84977. e-mail: [email protected] Volume 16, Number 3, 2003 249 The International Journal of Prosthodontics Posts and Cores as Single-Crown Abutments Ellner et al 7 Group 4 6 Group 3 5 Group 2 4 Group 1 3 2 1 No. of posts and cores 0 15 14 13 12 11 21 22 23 24 25 45 44 43 33 34 35 Tooth No. Fig 1 Distribution of posts and cores according to group (see Materials and Methods) and tooth (Fédération Dentaire Internationale tooth-numbering system). Study Criteria Endodontic Treatment Clinical inclusion criteria were: If the root filling of the tooth to undergo post-and-core buildup had a radiologically detectable poor seal, was • One or more single-rooted teeth in need of a sin- less than 3 mm from the radiologic apex, or had an api- gle crown and not intended for use in the support cal radiolucency near the tooth, the tooth was en- of a removable partial denture (Fig 1). dodontically retreated. All root canals had been filled • No marked signs of bruxism, expressed as heavy with gutta percha. The gutta percha was removed with attrition. A limited number of wear facets on the a Gates reamer (Hager & Meisinger). The periapical remaining teeth were accepted. conditions were classified according to Petersson et al19: • At least 2 mm of remaining vertical marginal tooth substance available for ferrule preparation. • Normal = Apical periodontal ligament space not more than double the width of the other parts of Some of the teeth had a screw post retaining an the root; appearance of the surrounding osseous amalgam crown; none of these posts had been structure is normal. placed more than 5 years before the tooth was in- • Bone destruction = Periapical radiolucency ob- cluded in the study, and the screw post was re- served; bone destruction ≤ 5 mm and > 5 mm moved. were registered separately. At the initial examination, the following general • Periapical conditions not evaluable = Poor radi- clinical and radiologic factors were evaluated: ographic quality; periapical structures impossible to evaluate. • Clinical and radiologic caries for all teeth. • Sagittal, transverse, and vertical maxilloman- Post-and-Core Designs dibular relationships. • Occlusion, including intercuspal contact on teeth • Group 1 = Conventional tapered posts and cores with posts and cores (stable/unstable). Any oc- cast in a type III gold alloy according to Zarb et clusal interference was noted and adjusted. al20 (n = 14) •Occlusion in lateral excursions (balanced/unbal- •Group 2 = ParaPost system with prefabricated anced). Canine-protected articulation was regis- posts in nonoxidizing gold alloy and cast cores in tered separately. a type III gold alloy (n = 13) • Plaque at four surfaces: mesial, buccal, distal, • Group 3 = ParaPost system with cast posts and and lingual, after use of a dye solution (yes/no). cores in a type III gold alloy after the use of pre- • Pocket depth at six surfaces: mesiobuccal, buccal, fabricated burnout posts (n = 13) distobuccal, distolingual, lingual, and mesiolin- • Group 4 = Radix-Anchor (Maillefer) threaded ti- gual. tanium posts with cores in chemically cured resin • Bleeding on probing of pocket depths (yes/no). composite (n = 10) •Gingival retractions, gingival swelling, cracks, and so on, around the experimental tooth. The type III gold alloys used were JS C-guld (JS Sjöding) • Periapical conditions. Intraoral radiographs were and Protor (Cendres & Métaux). Concise (3M) and made using the long-cone parallel technique. Adaptic (Dentsply) were the resin composites used. The International Journal of Prosthodontics 250 Volume 16, Number 3, 2003 Ellner et al Posts and Cores as Single-Crown Abutments 20 18 16 14 12 10 8 No. of posts 6 4 2 0 678910111213 Post length (mm) Fig 2 Number of posts according to post length as measured on the working cast; light gray bars = lost posts and cores. The first 40 teeth were randomly assigned to one of 4, the reamers provided by the manufacturers were the above groups. Radix-Anchor was excluded from used. The transition between the post and the core in the randomization of the last 10 teeth, since there were all systems was conical, and the shape of the holes for indications that the system was not suitable for use in the posts was oval to prevent rotation, except in the all situations. During preparation of the core buildup Radix-Anchor system. Care was taken to prepare the on incisors with a large angulation between the crown outer surfaces of the root parallel at least 2 mm to cre- and the root, a large portion of the core-retention part ate a ferrule effect. The finishing line was accomplished of the Radix-Anchor post had to be removed. This cre- as a shallow chamfer preparation. A polyvinyl siloxane ated a problem, as the teeth in the study had been ran- material, President (Coltène/Whaledent), was used for domized, which made it mandatory to treat the se- impression taking. Before cementation of the post and lected tooth with the randomized post-and-core core, the inner surface of the root canal was gently combination. To preserve the random design of the coarsened with a medium-grit diamond on a low-speed study as much as possible, group 4 was excluded contra-angle handpiece to create surface roughness. from the randomization process and teeth were only The root canal was thoroughly cleaned with 3% hy- assigned to groups 1, 2, or 3 (Fig 1). drogen peroxide, Tubulucid (an ethylenediaminete- traacetic acid [EDTA]–containing cleaner; Dental Clinical Preparation Therapeutics), and 96% alcohol using a rotating brush. All posts and cores were cemented with zinc-phosphate Five experienced dentists performed the initial cement (Dentsply/DeTrey). The crowns—metal ce- prosthodontic treatment. Two clinicians placed one ramic or type III gold alloy with acrylic resin facing— post and core each, one placed four posts and cores, were placed using the same luting cement. and another placed five. The remaining 39 posts and The patients were re-examined regularly until 1999. cores were inserted by one of the authors.