Resistance to horizontal forces of dowel and amalgam‐core restorations: a comparative study

Abstract

Four designs of amalgam-core anchorage were compared in a laboratory study for the inability to withstand the horizontal component of occlusal force. Amalgam cores were constructed for extracted teeth with either composite resin-cemented Dentatus dowels, or with Para-post or Flexi-post dowels cemented with phosphate cement. All the posts were of comparable length and diameter. These anchorage designs were compared with each other and to a self-threading (TMS) pin-retained amalgam core, by application of horizontal force and recording forces causing failure. Flexi-post-retained amalgam cores failed at a mean force of 36.5 (+/- 8.5) kg while Dentatus-retained and Para-post-retained cores failed at 41.7 (+/- 8.0) kg and 46.6 (+/- 11.4) kg, respectively. TMS-retained cores resisted forces up to a mean force of 53.5 (+/- 4.5) kg. Patterns of failure varied widely among these groups. Composite resin-cemented Dentatus dowels were retained in the tooth in nine out of ten samples, while none of the ten Flexi-post dowels and only one of the ten Para-post dowels did so. Tooth fracture on failure occurred in seven out of ten Flexi-post-retained cores, while only three out of ten of the Para-post-retained cores and none of the Dentatus dowel-retained cores presented this unrepairable type of failure. Possible reasons for these differences are discussed.

Mechanical properties of endodontic posts

“…The major forces to which a post is exposed act, more-or-less, at right angles to the long axis of the post (Gordon & Metzger, 1987). That is, the major forces are of concern to stability rather than retention (Fig.…”

Mechanical properties of endodontic posts

“…It is our contention that retention has been given far too much importance in the design of prefabricated endodontic posts. The major forces to which a post is exposed act, more-or-less, at right angles to the long axis of the post (Gordon & Metzger, 1987). That is, the major forces are of concern to stability rather than Gordon 8-Metzger (1987).…”