Oral Health Group

Mix and Match; Catch as Catch Can


June 10, 2010
by ken

With the profundity of restorative materials expanding the marketplace; it’s long overdue to look at how they impact on one another and moreover on natural teeth.  The following is from Podium by Ivoclar Vivadent………

Since the introduction of IPS e.max,
monolithic all-ceramic restorations have continued to gain momentum. Both
clinicians and laboratory technicians who have experienced fracture issues with
bi-layer all-ceramic systems are rapidly moving to a monolithic alternative. IPS
e.max Lithium Disilicate offers dentistry the most durable, highly esthetic
all-ceramic option available today. In addition to the monolithic IPS e.max
Lithium Disilicate, several manufacturers have begun to offer monolithic
zirconia as a high strength all-ceramic alternative to cast gold crowns where
limited reduction is provided. Most recently a study was performed at the
University of
Alabama
evaluating the wear
of various all-ceramic systems against natural enamel. The results of the study
demonstrate that additional testing of full-contour zirconia restorations on
opposing dentition should be conducted.
20100610_chart.jpg

Wear of Enamel Antagonist to Ceramic Surfaces

GHUMAN T, BECK P,
RAMP LC, CAKIR D, and BURGESS J, J Dent Res 89 (Spec Iss B):1394,
2010

Objectives: To measure
and compare wear of human occlusal enamel opposing three ceramic materials.
Methods: Enamel styli (n=10) were prepared from caries-free maxillary premolar
cusps. After wet polishing the enamel with a series of 400-, 600- &
1200-grit SiC paper, the enamel styli were mounted on the UAB wear testing
device. Flat rectangular ceramic blocks (n=10) (IPS e.max CAD/Ivoclar Vivadent,
LAVA core/3MESPE, LAVA veneering porcelain) were placed into brass holders using
self-cured acrylic and polished with a series of 400-, 600-, and 1200-grit SiC
paper. They were wet-finished (0.05ì alumina slurry/polishing cloth), cleaned
(ultrasonic bath/5min/ distilled water) and stored (24hrs/37°C). Wear test was
conducted at 32°C using a 50ì polymer-bead slurry (15g+9g physiologic saline)
against enamel styli (load=40N/1.2Hz/200,000cycles). Specimens were positioned
so that the flat surface was inclined 30°. After the enamel styli contacted the
ceramic specimen, a 2mm slide across the surface under a constant of 40N load
occurred. Impressions of ceramic and enamel styli were taken before and after
load cycling (Imprint light body/3MESPE) and poured with a low expansion die
stone (Silky rock, Whip Mix, type 4). Casts were scanned before and after
testing using a 3D non-contact profilometer (PROSCAN2000/Scantron/UK). Wear
volumes were measured by superimposing before and after images (ProForm
Software/Scantron/UK). Data analyzed with one-way ANOVA and Tukey/Kramer tests
(p=0.05).

Results: Wear volume:
Enamel had significantly greater wear against the LAVA core material
(p<0.0001) than all other comparisons. Other differences were not
significant.

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