Int Poster J Dent Oral Med 2011, Vol 13 No 3, Poster 544
The depth of cure of composite resin in connection of the applied dose of light
Dr. Britta Leubecher, Frank Bögershausen, Ostap Elert, Eugen Wellem, Prof. Dr. Michael Gente,
University of Marburg, Devision of Orofacial Prosthodontics and functional Education, Marburg, Germany
12.-13. November 2010
German Dental Conference 2010
Frankfurt am Main
What correlation exists between the dose of light and the depth of cure of composite resin?
Can the depth of cure be increased by enhancement of the dose of light?
Development of a theoretical model for the correlation between the applied amount of light and the depth of cure.
Material and Methods
The hardening depths were determined by means of ISO 4049 after radiation of various samples of composite resins of different manufacturers und shades with a LED polymerization light (Celalux, VOCO with lambda= 460 ± 20 nm) of 4,44 J/cm² (5 sec.), 9,10 J/cm² (10 sec.), 18,2 J/cm² (20 sec.) and 36,4 J/cm² (40 sec.).
The depth of cure d increases with rising dose of light D and decreases with ascending opacity of the composite resin. The increase of d is nonlinear and decreases with rising time of radiation (Fig. 1). A constant growth of depth of cure can be measured with a duplication of exposure time (Fig. 2).
The depth of cure can be described in close approximation (r> 0,9968) by the equation d = b× lnD + a
|Fig. 1: Depth of cure versus exposure time
||Fig. 2: Depth of cure as a function of dose of light
For the in the depth d applied and for hardening necessary dose of light Dmin applies according to Lambert-Beer-Law:
A: Depth of cure in mm, achieved with 10 J÷cm² dose of light
B: Increase of depth of cure in mm with duplication of the dose of light
- Several thin layers (layering technique) require a shorter exposure time than one thick layer (block technique).
- With voluminous restorations: additional hardening in depths (d> 1,5×A) is nearly impossible.
- It is proposed that the manufacturers of the composite resins publish the for their products applicable constants A and B and calibrate the scales of the light curing units in J÷cm ².
|Fig. 3: Constants A and B for the analyzed composite resins using the LED light curing unit Celalux (Fa. VOCO)
This Poster was submitted by Dr. Britta Leubecher.
Dr. Britta Leubecher
University of Marburg
Devision of Orofacial Prosthodontics and functional Education