Florin Eggmann1, Fabio Schiavone2, Julia Amato3, Annika Vahle4, Roland Weiger3, Nicola U Zitzmann2. 1. Department of Periodontology, Endodontology, and Cariology, University Center for Dental Medicine UZB, University of Basel, Mattenstrasse 40, CH-4058, Basel, Switzerland. florin.eggmann@unibas.ch. 2. Department of Reconstructive Dentistry, University Center for Dental Medicine UZB, University of Basel, Basel, Switzerland. 3. Department of Periodontology, Endodontology, and Cariology, University Center for Dental Medicine UZB, University of Basel, Mattenstrasse 40, CH-4058, Basel, Switzerland. 4. VITA Zahnfabrik H. Rauter GmbH & Co. KG, Bad Säckingen, Germany.
Abstract
OBJECTIVES: This laboratory study aimed to assess the effects of ultrasonic instrumentation, simulating 10 years of supportive periodontal therapy (SPT), on single-unit crowns. MATERIALS AND METHODS: Standardized crowns were fabricated from porcelain-fused-to-metal (PFM) (n = 12), zirconia (ZrO2) (n = 12), lithium disilicate (LDS) (n = 12), feldspar ceramic (FSFC) (n = 6), and polymer-infiltrated ceramic network material (PICN) (n = 6). The crowns, luted on PICN abutments with resin-based luting material (RBLM), and if applicable glass ionomer cement (GILC), underwent thermal cycling and trimonthly ultrasonic instrumentation. After 1 and 10 years of simulated SPT, restoration quality assessments were performed, comprising profilometric surface roughness measurements, marginal integrity evaluations, and scores for luting material remnants and visible cracks. The statistical analysis included multiple logistic regressions with nested designs (α = 0.05). RESULTS: During simulated SPT, bulk fractures (n = 2) and a de-cementation failure (n = 1) of LDS and ZrO2 crowns were observed. No significant change in roughness was detected after 10 years (p = 0.078). Over time, marginal defects increased (p = 0.010), with PFM crowns showing the highest rate of chippings at sites with a narrow shoulder. Fewer marginal defects were detectable on crowns luted with RBLM compared with GILC (p = 0.005). Luting material remnants decreased during SPT (p < 0.001). Ultrasonic instrumentation caused cracks in most crown materials, in particular at sites with a narrow shoulder and in PFM crowns. CONCLUSIONS: Repeated ultrasonic instrumentation may damage single-unit crowns. PFM crowns with a narrow, all-ceramic margin are especially prone to defects. CLINICAL RELEVANCE: Frequent ultrasonic instrumentation of restoration margins of fixed dental prostheses, PFM crowns in particular, ought to be avoided.
OBJECTIVES: This laboratory study aimed to assess the effects of ultrasonic instrumentation, simulating 10 years of supportive periodontal therapy (SPT), on single-unit crowns. MATERIALS AND METHODS: Standardized crowns were fabricated from porcelain-fused-to-metal (PFM) (n = 12), zirconia (ZrO2) (n = 12), lithium disilicate (LDS) (n = 12), feldspar ceramic (FSFC) (n = 6), and polymer-infiltrated ceramic network material (PICN) (n = 6). The crowns, luted on PICN abutments with resin-based luting material (RBLM), and if applicable glass ionomer cement (GILC), underwent thermal cycling and trimonthly ultrasonic instrumentation. After 1 and 10 years of simulated SPT, restoration quality assessments were performed, comprising profilometric surface roughness measurements, marginal integrity evaluations, and scores for luting material remnants and visible cracks. The statistical analysis included multiple logistic regressions with nested designs (α = 0.05). RESULTS: During simulated SPT, bulk fractures (n = 2) and a de-cementation failure (n = 1) of LDS and ZrO2 crowns were observed. No significant change in roughness was detected after 10 years (p = 0.078). Over time, marginal defects increased (p = 0.010), with PFM crowns showing the highest rate of chippings at sites with a narrow shoulder. Fewer marginal defects were detectable on crowns luted with RBLM compared with GILC (p = 0.005). Luting material remnants decreased during SPT (p < 0.001). Ultrasonic instrumentation caused cracks in most crown materials, in particular at sites with a narrow shoulder and in PFM crowns. CONCLUSIONS: Repeated ultrasonic instrumentation may damage single-unit crowns. PFM crowns with a narrow, all-ceramic margin are especially prone to defects. CLINICAL RELEVANCE: Frequent ultrasonic instrumentation of restoration margins of fixed dental prostheses, PFM crowns in particular, ought to be avoided.
Authors: Giovanni E Salvi; Daniel C Mischler; Kurt Schmidlin; Giedre Matuliene; Bjarni E Pjetursson; Urs Brägger; Niklaus P Lang Journal: J Clin Periodontol Date: 2014-05-26 Impact factor: 8.728