In-vitro investigation on suitability of light-cured resins for interocclusal splints : part II: surface hardness.
OBJECTIVE
The aim of the present study was to determine the surface hardness of light- and auto-cured resins for the fabrication of occlusal splints employing Vickers hardness measurements.


METHODS
In this study we used three auto-polymerized resins (Palapress, Orthocryl, Steady-Resin M) and four light-polymerized resins (Acrylight, Primosplint, Triad Tran- Sheet Colorless and Triad TranSheet Pink). The Vickers hardness measurement was carried out by means of a universal Durimet indenter applying a test load of 50 g for 30 seconds. The light-cured resins were polymerized in a Tagris Power light oven for 10 and 15 minutes each. Three separate test series were carried out (the hardness of plates under optimal conditions and of occlusal splints was measured, and the curing of light-polymerizing materials in layers of varying depth was evaluated). Data underwent statistical analysis via ANOVA and the Scheffé test.


RESULTS
The microhardness determined in each case amounted to values between 10.4 HV 0.5 and 39.3 HV 0.5. The Vickers hardness determined for the plates that had been produced under optimal conditions demonstrated that their surface was significantly (p < 0.05) harder than that of cylinders and splints. The hardness values of the light-cured material Triad TranSheet Pink (39.3 HV 0.5) were significantly higher (p < 0.05) than those of all other resins. In all auto-polymerized resins, the surface hardness of the samples we examined (in the form of plates and splints) was significantly lower (p < 0.05) than that of the light-cured materials Triad TranSheet Pink and Colorless.


CONCLUSIONS
The results we have obtained so far concerning surface hardness indicate that, in the fabrication of occlusal splints, light-cured resins may represent an alternative to auto-polymerizing materials.
Danesh
Gholamreza
G
Department of Orthodontics and Dentofacial Orthopedics, University of Münster, Münster, Germany. siamak@uni-muenster.de
Lippold
Carsten
C
Ziebura
Thomas
T
Reinhardt
Klaus-Jürgen
KJ
Schäfer
Edgar
E
Ehmer
Ulrike
U
D000042:Absorption / Q000528:radiation effects; D000180:Acrylic Resins / Q000737:chemistry* / Q000528:radiation effects*; D003764:Dental Materials / Q000737:chemistry* / Q000528:radiation effects*; D004548:Elasticity / Q000528:radiation effects; D006244:Hardness / Q000528:radiation effects; D008027:Light; D008422:Materials Testing; D019563:Mechanics; D017090:Occlusal Splints; D010777:Photochemistry / Q000295:instrumentation / Q000379:methods; D013499:Surface Properties / Q000528:radiation effects; D013718:Tensile Strength / Q000528:radiation effects; D014867:Water / Q000737:chemistry*
D000180:Acrylic Resins; D003764:Dental Materials; D014867:Water