Dental Research Today is a free monthly online journal that collates and summarizes the latest research about Dental, including details on implants, health, hygiene, cosmetic, dentistry.

Effect of mouth-motion fatigue and thermal cycling on the marginal accuracy of partial coverage restorations made of various dental materials.

Stappert CF, Chitmongkolsuk S, Silva NR, Att W, Strub JR

Department of Prosthodontics, Albert-Ludwigs-University, Faculty of Dentistry, Freiburg, Germany; Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, USA.

OBJECTIVES: To investigate the influence of mouth-motion fatigue on marginal-accuracy of partial-coverage-restorations-(PCRs) of various dental materials. METHODS: Eighty molars were prepared equally and divided into five groups (n=16). PCRs were fabricated of following dental materials: Group-GO=Gold-Pontor-MPF(double dagger), Group-TA=Targis*, Group-EX=IPS-e.max-Press*, Group-EM=IPS-Empress*, Group-PC=ProCAD*/Cerec 3(dagger) ((double dagger)Metalor/*Ivoclar-Vivadent/(dagger)Sirona-Dental-System). Gold-PCRs were cemented conventionally. Residual 64 PCRs were adhesively luted and subjected to masticatory loading (1.2million-cycles, 1.6Hz, 49N) and thermal cycling (5 degrees C/55 degrees C, 60s, dwell-time, 5500cycles). Discrepancies in marginal-accuracy were examined on epoxy replicas (200x magnification). Statistical analysis was performed by unpaired and paired t-tests (alpha=0.05). RESULTS: After cementing, marginal-accuracy (geometrical mean)[95% confidence limits] was recorded: GO-47[43-51]mum, TA-42[38-45]mum, EX-60[52-67]mum, EM-52[45-60]mum and PC-75[59-94]mum. No significant differences were found between groups GO, TA and EM. Values of Group-EX were significantly higher compared to Group-TA (p=0.04). Group-PC demonstrated significantly decreased marginal-accuracy towards groups GO (p=0.03) and TA (p=0.02). Except for Group-GO (p=0.01), no significant changes in marginal-accuracy were observed after mouth-motion fatigue and thermal cycling (GO-42[38-45]mum, TA-42[38-47]mum, EX-56[49-65]mum, EM-54[46-64]mum and PC-71[59-84]mum). However, Group-GO and Group-EM showed significant deviations in marginal-accuracy after aging (p=0.04). Marginal discrepancies of groups EX and EM were similar (p=1.0). Values of Group-PC were significantly higher when compared to groups GO (p=0.01) and TA (p=0.02). Buccal-lingual marginal discrepancies were significantly higher than mesial-distal in all groups and stages. SIGNIFICANCE: Cast-gold-PCRs demonstrated superior marginal-accuracy, followed by indirect ceromer PCRs. All-ceramic PCRs showed in vitro clinical acceptable marginal widths, even though CAD/CAM fabrication slightly compromised marginal-accuracy. Since preparation margins were not exposed to occlusal loading directly, increased marginal discrepancies due to marginal chipping during mouth-motion fatigue were not experienced.

Published 8 April 2008 in Dent Mater.
Full-text of this article is available online (may require subscription).

© 2004-2008 Dental Research Today. All Rights Reserved.