Objective: The hypothesis of this study was that the fracture load of incisor teeth restored using short, threaded, parallel-sided posts (TMP) is, under special conditions, not inferior to that of teeth restored using long TMPs or fibre-reinforced posts (FRP).
Methodology: Seventy-two maxillary incisors and 72 mandibular incisors were collected. Sixty-four in each group were root filled; in half of these FRPs were cemented, and in the other half TMPs were used. Half of the FRPs were pretreated; the others were not pretreated. In the TMP-group, half of the teeth received a long post (10 mm), the other half a short post (3 mm). Crowns were fabricated and cemented with Ketac-cem or Panavia. Eight maxillary incisors and eight mandibular incisors with intact natural crowns were used as control groups. All specimens were loaded until fracture.
Results: Fracture loads were higher for pretreated FRPs than for untreated FRPs. If the FRPs were not pretreated, fracture loads for maxillary incisors after use of short metal posts were significantly higher (248 N compared with 133 N, P = 0.027). Fracture loads for teeth restored using long TMPs were not higher than for teeth restored using short TMPs (277 N compared with 266 N). Fracture loads for mandibular incisors restored using long (10 mm) pretreated FRP were higher than for mandibular incisors restored using short (3 mm) metal posts (436 N compared with 285 N). Cementation of the crowns using an adhesive resin cement did not increase the fracture load for mandibular incisors, whereas for maxillary incisors, this cementation technique tended to increase fracture loads in teeth restored with FRP, although this increase was not significant at the P < 0.05 level (P = 0.06). In both groups, fracture loads were higher for mandibular incisors.
Conclusions: Short, threaded, parallel-sided metal posts might be an alternative to fibre- reinforced posts for maxillary incisors, for teeth with short roots or when FRP cannot be pretreated.