Influence of different transitional restorations on the fracture resistance of premolar teeth

Controversy exists over the most favorable material and type of restoration to be used to transitionally restore teeth destined to be crowned. This in vitro study uses fracture resistance testing to compare eight different tr ansitional restorations in maxillary premolars. Ninety sound maxillary prem olars were randomly selected and allocated to nine groups, each comprising 10 teeth. One group remained unrestored and was used as the control. Teeth in the remaining groups were prepared to a standard cavity form using: a co py milling process removing the palatal cusp. Restorations were placed usin g amalgam with dentin pins and cavity varnish; amalgam with an amalgam bond ing agent; resin composite with dentin pins and a dentin bonding agent; res in composite with a dentin bonding agent only; resin-modified glass ionomer with dentin pins; resin-modified glass ionomer cement alone and cermet wit h dentin pins and cermet alone. Each restored tooth was then subjected to a xial loading via a bar contacting the buccal and restored palatal cusps unt il failure of the restored tooth occurred. The mean load-to-fracture values were statistically compared and the modes of failure recorded. It was foun d that the choice of restorative material and type of restoration had littl e effect on the fracture resistance of the restored tooth with the exceptio n of those teeth restored with reinforced glass ionomer cement alone, which exhibited a significantly lower resistance to fracture than the other rest ored teeth. However, the choice of restorative material/technique did influ ence the mode of failure. Failure in teeth restored with resin-modified gla ss ionomer cement alone produced the least damage to the remaining tooth ti ssue when failure occurred. Consequently, this material may offer the most favorable range of properties for the transitional restoration of extensive ly broken-down maxillary premolar teeth destined to be crowned. Furthermore , the findings of this study fail to support the use of dentin pins in the placement of bonded build-up restorations.