To investigate the influence of mouth-motion fatigue on marginal-accuracy of partial-coverage-restorations-(PCRs)
of various dental materials.
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 (200 x magnification). Statistical analysis was performed
by unpaired and paired t-tests (alpha=0.05).
After cementing, marginal-accuracy (geometrical mean)[95% confidence limits] was recorded:
GO-47[43-51]microm, TA-42[38-45]microm, EX-60[52-67]microm, EM-52[45-60]microm and
PC-75[59-94]microm. 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]microm,
TA-42[38-47]microm, EX-56[49-65]microm, EM-54[46-64]microm and PC-71[59-84]microm).
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.
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.