Sir, we would like to offer some comments in relation to the interpretation of our published research data,1 as part of a recent articlepublished in the BDJ.2With reference to our investigation reporting on the 5.5-year clinical performance of direct composite resin restorations for the full mouth rehabilitation for patients with severe tooth wear, Dr Hassall has stated that, 'Level 1 and Level 2 failures required repair or replacement, while Level 3 failures (small chips) were polished or accepted. Combined Level 1 and 2 failures were high at 32.5% and if Level 3 failures were included, failure rose to 67.6% after only five years'.

As part of our investigation, there were 676 anterior direct resin composite restorations prescribed for the treatment of tooth wear, observed for a mean period of 62.4 months. Failures were described as, either, a 'Level 1' failure that had a severe deficiency and required replacement of the restoration (to include the need for endodontic treatment or a dental extraction - a catastrophic failure), 'Level 2,' a type of failure which referred to the presence of localised deficiencies that were repaired, and 'Level 3' failure, denoting the presence of a small material chip, which would require refurbishment by polishing or needed no further intervention. As part of the data analysis, the following descriptions were applied; 'Level 1' - a catastrophic failure, 'Level 2-,' combined Level 1 and 2 failures and 'Level 3-,' all levels of failure observed. In total at the 5.5-year mark, there were 19 Level 1 failures (2.8%), 58 Level 2- failures (8.6%) and 72, Level 3- failures (10.7%). The combined Level 1 and Level 2 failures for the overall anterior restorations were in fact 8.6% (and not 32.5%) and 10.7% (opposed to the quoted 67.6%) for the overall sample, with an overall annual failure rate for all types of failures combined (Level 3-) of approximately 2.2%.

The author of the BDJ article has referred to an overall rate of failure that was approximately six times greater than the actual finding. This is somewhat misleading. Whilst significantly higher failure rates were observed where anterior veneer restorations required further visits for completion, based on our overall findings, we concluded that direct resin composite, with proper case planning,3 can offer an acceptable medium-term solution for treating severe generalised tooth wear. This included the prescription of posterior direct resin composite restorations, noting, higher-risk patients were not excluded in our full sample of 1,269 restorations. This contrasts with the author's interpretation of our data, and this is of material relevance. The use of direct resin composite applied in an additive, minimally invasive manner has many benefits for the restorative rehabilitation of tooth wear, to include some documented improvements to patients' oral health-related quality of life post-intervention.

We feel the author is incorrectly using our paper to support his point of view and would kindly request an appropriate erratum to the published paper.

Dominic C. Hassall responds: The paper considered1 presents data for all regions of the mouth including the anterior maxilla for one session and two session direct composite veneers on maxillary anterior teeth for advanced tooth wear.

My paper2 selected the two session anterior maxillary data as this is the most aesthetically demanding area and it clearly highlights the limitations of traditional composite techniques.

For two session maxillary veneer placement combined level 1, 2 and 3 failure is indeed very high at 67.7% over a relatively short study period. Even if the more minor level 3 failures are excluded the failure rate is still high at 32.5%. Although less failure is associated with one session maxillary veneer placement combined failure was also very high at 46.1% and still high at 26.9% if level 3 failures are excluded.

Other areas of the mouth also displayed high failure, for example combined level 1, 2 and 3 failure in the mandibular molar area is 42.8% or 22.5% if level 3 failures are excluded.

Level 3 failures are actually of clinical significance as these small chips further deteriorate and there are time implications if polishing is required or the roughness, sharpness or staining requires attention.

Over many years of using traditional composite techniques I like many other clinicians have experienced these high failure/repair/refurbishment/polishing levels which are disappointing and frustrating for both patients and clinicians. Unlike the study where the treatment was provided free of charge, in many countries the majority of tooth wear is treated privately where the significant time involved has financial implications for patients.

This is why over the last decade fresh approaches such as the Bioclear composite approach and monolithic high strength ceramics have gained worldwide popularity due to their longevity and low maintenance.

It is worth noting that it took up to 15 hours to complete the rehabilitations which is a signficant time investment and polishing due to extrinsic staining or surface roughness was not even registered as failure but again has significant clinical time implications.

The use of your data is fully justified to support why a more contemporary composite approach has been adopted by many clinicians worldwide, which in the experience of many of us has dramatically reduced the signifcant failure and ongoing high maintenace rates presented in your study.