Six-year analysis of posterior zirconia crowns with vertical margin preparations

Background The application of vertical margins for crown preparations is increasing in popularity but limited long-term clinical outcome data exist.Aim To audit clinical outcomes for 73 teeth after vertical preparation for knife-edge zirconia crowns on posterior teeth in general practice.Methods In total, 73 posterior teeth had knife-edge zirconia crowns placed after vertical finish line preparation. The outcomes for these teeth were analysed from a retrospective audit of clinical records.Results The mean follow-up time was 62 months (SD: 21 months; range: 12-93). Eight teeth experienced complications during the follow-up period, with two of these teeth ultimately being extracted (one due to tooth fracture and one due to caries at the crown margin). The remaining six teeth were still functioning. Three of these had crown replacements, one required re-root canal treatment and two teeth (in the same patient) had unstable periodontitis which worsened since placement of crowns. Only the patient with unstable periodontitis showed any change in alveolar bone height on radiographic follow-up; 68 teeth with radiographic follow-up available showed no changes in alveolar bone levels. The mean bleeding score for the crowned teeth was higher than the mean bleeding score for the control tooth, but this was not statistically significant.Conclusion This retrospective evaluation has shown favourable outcomes for 71 teeth after vertical preparation for knife-edge crowns. Longer follow-up is needed but the present results show that the technique is a viable procedure with potential advantages.