The Impact of Preservation of Tooth Structure on the Outcome of Endodontic and Restorative Treatment

A systematic review helped in identifying a gap in literature, namely the evidence for the use of onlays as post endodontic restorations.

A prospective study was conducted a Guy’s Hospital, Kings College, London. A cohort of 143 patients participated in the clinical trial. Root canal treatment of teeth was performed followed by provision of a CAD CAM generated onlays or full crowns. 124 patients returned to have their restorations assessed.

An ex- vivo laboratory study was conducted to assess the wear of enamel and polymer infiltrated nano ceramics and compare this to the wear measured in vivo in the clinical trial.

The pooled relative risk of failure in the root canal treated teeth was 2.27 with 95% confidence interval from 1.77 to 2.91, indicating more frequent failures in root canal treated teeth compared to vital teeth.

The prospective data revealed no statistically significant difference between the clinical performance of onlays and crowns on ETT. The results assessed using FDI and modified USPHS criteria were similar. Statistically significant prognostic factors for endodontic treatment included presence of voids, length of root canal filling, presence, and size of periapical lesion. The favourable outcome using CBCT was 78.5% while it was 88.8% using PA radiography.

The novel nanohybrid ceramics displayed significantly more wear than enamel ex vivo. However in vivo the wear of enamel was not significantly different from that of Cerasmart, this is a very important property of this nanohybrid ceramic, particularly considering that many of the other commonly used ceramic materials such as zirconia and lithium disilicate display less wear than enamel and are known to cause significant wear of the opposing teeth.