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S. B. Mehta and B. J. Millar British Dental Journal 2008; 205: E23

Editor's summary

In clinical practice as well as in the arena of research studies one fact comes through as strikingly obvious: that nothing we are able to provide as clinicians matches up to that with which nature endows us. The confluence of materials, techniques and altered biological tissues often seems to conspire to confound our best efforts to restore damaged hard tissues.

Thus it is that as we make gradual progress in moving from metal posts as a foundation to restore endodontically treated teeth, we also need to take account of the cements that we use to secure the fibre resin equivalants. This study provides some valuable information on the comparison of the medium-term success of two luting agents, indicating that the choice of material can influence the prognostic outcome. What the study also highlights is the number of other factors that have to be considered not only in the meaningful study of the subject but also in contemplating the clinical situation. The causes of failure were associated with root fracture, decementation, fracture at the post-core interface, endodontic failure and marginal caries. In addition, significantly higher failure rates were observed to occur in partially dentate patients, in those with parafunctional habits and also amongst anterior teeth. A plethora of considerations around which to negotiate.

We would all like to be able to see into the future and predict which treatments work best for longest. Sadly we cannot and our next best tool in this respect has to be research and extrapolation. The authors have provided us with some valuable indicators to guide our daily decision making based on observation, careful analysis and best practice. Only with the benefit of hindsight will we know with greater surety which method stood the test of time and function, in the interim we can reassure our patients that we are doing the best we can on the evidence we have.

The full paper can be accessed from the BDJ website ( http://www.bdj.co.uk ), under 'Research' in the table of contents for Volume 205 issue 11.

Stephen Hancocks, Editor-in-Chief

Author questions and answers

1. Why did you undertake this research?

Fibre resin posts (FRPs) have been developed to provide more aesthetic, biocompatible, retrievable and conservative alternatives to their traditional metallic endodontic post counterparts. Additionally, it has been postulated that FRPs, on account of their mechanical properties, would overcome the well documented problem of root fracture frequently associated with the use of metal posts. To date, there have been relatively few clinical studies undertaken to assess the performance of FRPs and very little is known about the influence of the type of resin lute used to place FRPs within the post canal. The purpose of this audit was to gain further information relevant to everyday restorative dental practice. The audit was undertaken as part of the fulfilment of a post-graduate degree.

2. What would you like to do next in this area to follow on from this work?

Of what little data is available on the clinical outlook of endodontically treated teeth restored by means of fibre resin post systems, much is short- to medium-term in duration. The undertaking of a 10 year survival assessment would provide much sought after information on the long-term performance of such post systems. It would also be interesting to evaluate the effect on clinical survival with the use of fibre resin posts of differing chemical, mechanical and physical properties, as would be the impact of the influence of differing types of resin lute, in particular the new generation of 'smart cements' (7th generation bonding agents).

Comment

Use of tooth coloured fibre posts is increasing but their clinical performance has been less extensively studied than use of metal posts. This study will, therefore, prove of interest to readers of the British Dental Journal. The significance of the choice of the two post luting agents is that one (Panavia F.2.0) has potential to chemically bond to the post while the other (Calibra) may not. A limitation of the study, fully admitted by the authors, is that it is a retrospective audit. Thus the review periods varied for each material and between materials, the time of placement using the two luting materials was consecutive rather than concurrent and the status of the dentition was not standardised, which could have impacted on the outcomes, as could the lack of standardisation of the distribution of groups of teeth in which posts were placed and the differences in sample sizes of the two groups evaluated.

The great strengths of the study, however, are that all posts and subsequent procedures were undertaken using a standardised technique and following manufacturer's instructions, by the same operator in the same general (private) practice. Unfortunately, again due to the nature of the audit, the assessment of failure or otherwise of the procedures was made by the operator and not a trained independent observer.

Correctly, in view of the nature of this study, no statistical analyses were attempted. Instead, descriptive statistics are provided. The relatively high rate of fracture at the post/core interface identified in the study is of concern and is consistent with in vitro test results. The relatively low level of root fracture is consistent with in vivo studies and is a potential advantage over metal post systems.

While no firm conclusions can be drawn with regard to the choice of luting material, valuable areas for further studies are highlighted.