High volume individual fibre post versus low volume fibre post: the fracture load of the restored tooth.
OBJECTIVE
The purpose of this study was to evaluate the fracture loads of post-and-core systems with two different individually formed fibre post designs and polymerization conditions.


METHODS
Totally seventy-two (n=8/group) bovine teeth were cut and made up the root length of 15.0mm. They were divided into 3 main groups (Group A, B, C). A: one glass fibre post was light-cured before cementation, B: fibres were bundled to fill the entire root canal opening and light-cured before cementation, C: one unpolymerized glass fibre post was inserted into cement-filled root canal and light-cured with luting cement (ParaCem). Moreover specimens of each group were divided into 3 subgroups according to the post length: subgroup 1: 10mm; subgroup 2: 7.5mm; subgroup 3: 5.0mm. After cementation, the core was built up, and then made the composite resin crown (Filtek Z250). Fabricated specimen was loaded from 45° of palatal side at a crosshead speed of 1.0mm/min. The first load drop and maximum fracture loads were statistically analyzed by ANOVA and Tukey's test.


RESULTS
Maximum fracture load of Group B (433 N) and C (418 N) are significantly higher than Group A (284 N) (p<0.01). Short post (5mm) provided higher fracture loads in all main groups, especially in Group C.


CONCLUSIONS
Using short and thick fibre post system (the same diameter as the root canal) showed higher strength than one fibre post only. In addition, by curing the cement and the fibre material simultaneously, the strength of the restored tooth was increased.
Department of Crown and Bridge, School of Life Dentistry at Tokyo, The Nippon Dental University, 1-9-20 Fujimi, Chiyoda-ku, Tokyo 102-8159, Japan.
Minori
M
Hatta
Akikazu
A
Shinya
Pekka K
PK
Vallittu
Akiyoshi
A
Shinya
Lippo V J
LV
Lassila
D000818:Animals; D001696:Biomechanical Phenomena; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002417:Cattle; D002484:Cementation / Q000379:methods; D003188:Composite Resins / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D017267:Dental Prosthesis Design; D003786:Dental Pulp Cavity / Q000473:pathology; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis / Q000295:instrumentation; D005898:Glass / Q000737:chemistry*; D008689:Methacrylates / Q000737:chemistry; D058105:Polymerization; D019904:Polymethyl Methacrylate / Q000737:chemistry; D011176:Post and Core Technique / Q000295:instrumentation*; D019279:Resin Cements / Q000737:chemistry; D018915:Root Canal Preparation / Q000379:methods; D013314:Stress, Mechanical; D013499:Surface Properties; D014070:Tooth / Q000503:physiopathology*
D003188:Composite Resins; D003764:Dental Materials; C444701:Filtek Z250; D008689:Methacrylates; D019279:Resin Cements; C496140:everStick; C009753:fiberglass; D017438:Bisphenol A-Glycidyl Methacrylate; D019904:Polymethyl Methacrylate