Limited evidence for main reason for failure of partially excavated and restored teeth.

DATA SOURCES: Medline, PubMed, EMBASE and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched between Jan 1967 and Dec 2012. No grey literature searches were carried out.

STUDY SELECTION: Randomised and non-randomised, controlled and uncontrolled, pro- and retrospective clinical studies (in English or German) that investigated one- or two-step incomplete dentinal caries removal (where caries was >1/2 dentine thickness) were eligible. Studies had to have teeth that were clinically and/or radiologically vital, primary or permanent teeth requiring a restoration but with no pulp exposure.The main outcomes were; clinical or radiological failure based on reported re-treatment. Failures were classified where possible into pulpal (pain, clinical or radiographic signs of pathology) and non-pulpal (tooth or restoration fracture, restoration loss or breach in integrity, secondary or progressing residual caries or non-pulpal failures).

DATA EXTRACTION AND SYNTHESIS: Two authors independently reviewed the title and abstract of the articles (without blinding to authors or journals) and both extracted data, with discrepancies resolved through discussion or consultation with a third reviewer. Risk of bias was carried out using Cochrane collaboration guidelines and studies were assessed using GRADE criteria.Failure was calculated per year and annual failure rates weighted according to the number of teeth. Weighted annual failure rates were then used as the effect estimate for frequency and type of failure. Subgroup analyses were carried out, for factors influencing failure, in studies that compared teeth within one or more of the following groups: primary or permanent teeth; pulpal symptoms prior to treatment; single or multi-surface cavities; one- or two-step incomplete excavation; lining material; and restorative material.

RESULTS: Twenty-nine articles reporting 19 trials (12 randomised controlled trials, two controlled trials, five case series & retrospective studies), with a median follow up of 24 months (IQR; 12 to 48), were included. In 11 studies pulpal complications were the main reason for failure and only two studies found more non-pulpal than pulpal failures. Median annual failure rate was 3.8 (IQR; 1.4 to 4.4)From the sub-group analyses, there was significantly lower risk of failure for teeth with one- compared to those with two-step excavation (OR=0.21, 95%CI [0.08 to 0.55]) and for those with single compared with multi-surface lesions (OR=0.33, 95%CI [0.16 to 0.67]. Risk of bias scores varied widely and the quality of the studies was very low.

CONCLUSIONS: Following incomplete removal of deep caries, pulpal failure (pain, clinical or radiographic signs of pathology) was the most common failure type. One-step incomplete excavation for deep caries lesions reduced the risk of failure compared to two-step removal and multi-surface lesions had a higher risk of failure than single surface lesions.