Filtek Silorane composite: temperature changes during light-curing

Some time ago, my colleagues and I published a paper on temperature changes during curing of Filtek Silorane, Admira (ormocer) and Herculite XRV (microhybrid, control) composites. It was interesting to notice substantially higher temperature rise in Filtek Silorane compared to the other two materials. However, there was no difference in the temperature rise inside the pulp chamber, probably due to the insulating effect of the remaining dentine.

The abstract of this paper may be found on MEDLINE and I will be happy to email the full text to anyone interested in this subject. Feel free to contact me at vesna.miletic@gmail.com

J Esthet Restor Dent 2009;21(2):122-31.
Temperature changes in silorane-, ormocer-, and dimethacrylate-based composites and pulp chamber roof during light-curing.
Miletic V, Ivanovic V, Dzeletovic B, Lezaja M.

STATEMENT OF THE PROBLEM: Light-curing of resin-based composites (RBCs) is associated with temperature increase in the pulp chamber, which may have a detrimental effect on the vital pulp.
PURPOSE: The purpose of the study was to evaluate temperature changes of silorane-, ormocer-, and dimethacrylate-based RBCs at the bottom surface of the RBC and in the pulp chamber roof dentin (PCRD) during curing.  
MATERIALS AND METHODS: In part A, temperatures were measured for Filtek LS (3M ESPE, St. Paul, MN, USA), Admira (Voco GmbH, Cuxhaven, Germany), and Herculite XRV (Kerr Corp., Orange, CA, USA) with a high-power light-emitting diode (LED) unit by placing thermocouples in contact with the bottom surface of the material in standardized acrylic molds. In part B, temperature changes in PCRD were measured in extracted molars during light-curing of adhesives and RBCs in 2-mm-deep cavities with a remaining dentin thickness (RDT) of 1 mm.
RESULTS: Filtek LS showed a different temperature curve compared with Admira and Herculite XRV. Significantly higher temperatures were recorded for Filtek LS (p < 0.001) than for Admira and Herculite XRV in acrylic molds. Temperature rises recorded in PCRD for adhesives and RBCs were between 4.1 and 6.4 degrees C. No significant differences in PCRD temperatures were found between the three groups during adhesive curing and RBC curing (p > 0.05).  
CONCLUSIONS: Filtek LS showed a different heat-generation pattern from and significantly higher temperatures than Admira and Herculite XRV when the materials were tested in acrylic molds. Similar temperatures were recorded in the PCRD during curing of adhesives and RBCs.
CLINICAL SIGNIFICANCE: Although a substantial temperature rise in the bulk material occurred during light-curing of the three resin-based composites, a remaining dentin thickness of 1 mm caused a significant reduction in pulp chamber roof dentin temperatures. Temperatures measured in the pulp chamber roof dentin corresponding to the zone occupied by the postmitotic odontoblast layer were not statistically different for the three types of resin-based composites.

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Refractive Index of Methacrylate Monomers & Polymers

It is my pleasure to share this post originally published by Esstech, Inc. www.esstechinc.com
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TECHNICAL BULLETIN:  Refractive Index of Monomers and Their Respective Polymers

The refractive index (RI) of photopolymers is an essential property for many applications.  For optical and coating applications, the RI can be related to the resultant gloss or clarity upon cure.  Within the dental industry, the refractive index of the organic polymer matrix, must match that of the inorganic filler and substrate in order to avoid obvious “lines” where the product is applied.

Various factors affect refractive index values.  The presence of conjugated ring structures contributes to increasing RI.  In general, larger molecular weight monomers have a tendency to possess a higher RI in comparison to their lower molecular weight counterparts.  Similar to this trend, high molecular weight functional groups like methacrylates have higher RI than their acrylate counterparts. Higher atomic weight atoms also seem to be predisposed to having higher RI.

Recognizing the importance of refractive index to our customers, Esstech has assembled RI data for a portion of our existing monomer products as well as their corresponding homopolymers.

Maintaining its position as an industry innovator, Esstech has also created functional, high refractive index materials.  Contact us to learn more about these novel materials and how Esstech can make a material to match your application.

 (P) 800-245-3800 / (P) 610-521-3800 / techsupport@esstechinc.com / www.esstechinc.com

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