G T Rocca1, R Daher2, C M Saratti2, R Sedlacek3, T Suchy4, A J Feilzer5, I Krejci2. 1. Division of Cariology and Endodontology, School of Dentistry, University of Geneva, Geneva, Switzerland. Electronic address: giovanni.rocca@unige.ch. 2. Division of Cariology and Endodontology, School of Dentistry, University of Geneva, Geneva, Switzerland. 3. Laboratory of Biomechanics, Department of Mechanics, Biomechanics and Mechatronics, Faculty of Mechanical Engineering, Czech Technical University of Prague, Prague, Czech Republic. 4. Department of Composites and Carbon Materials, Institute of Rock Structure and Mechanics, Academy of Sciences of the Czech Republic, Prague, Czech Republic. 5. Department of Dental Materials Science, ACTA, Amsterdam, The Netherlands.
Abstract
OBJECTIVES: To explore fatigue limits of ceramic endocrowns for premolars. METHODS: Forty-eight devitalized premolars were cut at the CEJ. They were restored with standardized CAD-CAM lithium disilicate reinforced ceramic restorations (IPS e.max CAD, Ivoclar-Vivadent) and divided into four Groups (n=12): overlays (Group A, no endo-core, negative control), endocrowns with an endo-core of 2mm (Group B), 4mm (GroupC) and crowns with post and core (Group D, positive control). All specimens were first submitted to thermo-mechanical cyclic loading (TCML)(1.7Hz, 49N, 600000 cycles, 1500 thermo-cycles). Margins were analysed before and after the loading. Survived specimens were then submitted to cyclic isometric stepwise loading (5Hz, 200N to 1200N) until completion of 105000 cycles or failure. In case of fracture, fragments were analysed using SEM and failure mode was determined. Results of stepwise loading were statistically analysed by Kaplan-Meier life survival analysis and log rank test (p=0.05). RESULTS: All the specimens survived the TCML test except four specimens of Group A (early restorations' debonding). No difference in percentages of closed margins was found between endocrowns (Groups B, C) and crowns (Group D). After the stepwise test, differences in survival within the groups were not statistically significant. Most of restorations experienced non-reparable fracture. CONCLUSIONS: Endocrowns with both 2-mm and 4-mm long endo-cores displayed outcomes after fatigue equivalent to classical crowns. Results of this study discourage the use of flat overlays with only adhesive retention. CLINICAL SIGNIFICANCE: When restoring extremely destroyed devitalized premolars, adhesive strategies should be coupled to a macro-mechanical retention in the root.
OBJECTIVES: To explore fatigue limits of ceramic endocrowns for premolars. METHODS: Forty-eight devitalized premolars were cut at the CEJ. They were restored with standardized CAD-CAM lithium disilicate reinforced ceramic restorations (IPS e.max CAD, Ivoclar-Vivadent) and divided into four Groups (n=12): overlays (Group A, no endo-core, negative control), endocrowns with an endo-core of 2mm (Group B), 4mm (GroupC) and crowns with post and core (Group D, positive control). All specimens were first submitted to thermo-mechanical cyclic loading (TCML)(1.7Hz, 49N, 600000 cycles, 1500 thermo-cycles). Margins were analysed before and after the loading. Survived specimens were then submitted to cyclic isometric stepwise loading (5Hz, 200N to 1200N) until completion of 105000 cycles or failure. In case of fracture, fragments were analysed using SEM and failure mode was determined. Results of stepwise loading were statistically analysed by Kaplan-Meier life survival analysis and log rank test (p=0.05). RESULTS: All the specimens survived the TCML test except four specimens of Group A (early restorations' debonding). No difference in percentages of closed margins was found between endocrowns (Groups B, C) and crowns (Group D). After the stepwise test, differences in survival within the groups were not statistically significant. Most of restorations experienced non-reparable fracture. CONCLUSIONS: Endocrowns with both 2-mm and 4-mm long endo-cores displayed outcomes after fatigue equivalent to classical crowns. Results of this study discourage the use of flat overlays with only adhesive retention. CLINICAL SIGNIFICANCE: When restoring extremely destroyed devitalized premolars, adhesive strategies should be coupled to a macro-mechanical retention in the root.
Authors: Mario Dioguardi; Mario Alovisi; Giuseppe Troiano; Carlo Vito Alberto Caponio; Andrea Baldi; Giovanni Tommaso Rocca; Allegra Comba; Lorenzo Lo Muzio; Nicola Scotti Journal: Clin Oral Investig Date: 2021-10-10 Impact factor: 3.573
Authors: Luigi Giovanni Bernardo Sichi; Fernanda Zapater Pierre; Laura Viviana Calvache Arcila; Guilherme Schmitt de Andrade; João Paulo Mendes Tribst; Pietro Ausiello; Alessandro Espedito di Lauro; Alexandre Luiz Souto Borges Journal: Molecules Date: 2021-10-10 Impact factor: 4.411