In 2002 Versluis et al published an 11 page paper titled Residual Shrinkage Stress Distributions in Molars After Composite Restoration. Within their carefully worded analysis, they emphasized “Calculation of shrinkage stresses in a tooth-restoration complex is not trivial.”
18 years later, a presenter at Seattle Study Club trivialized polymerization shrinkage stress to promote the so-called “Bioclear Method” using 3M Filtek One bulk fill composite and anatomic mylar matrices (Bioclear Matrix). He cited no scientific evidence to back up his claims.
Rather, he used a series of FEA diagrams to artfully mislead the audience, making statements like “the bulk of the restoration is going into compression... that dark blue is compression.” He completely disregards the “spattering” in areas of higher stress where you’re likely to see debonding of composite over dentin.
The YouTube video has since been removed.
It’s unlikely there’s a respected scientist or researcher in adhesive dentistry that agrees with this presenter and his elementary ideas that “...polymerization shrinkage stresses in these modern preps is a good thing,” even if you “change to a negative c-factor, less than one,” which is conceptually and mathematically impossible.
In fact, researcher Alireza Sadr, DDS, PhD, who is Associate Director at Biomimetics Biomaterials Biophotonics & Technology (B4T) laboratory at University of Washington School of Dentistry, has published with colleagues a variety of interesting articles using state of the art Optical Coherence Tomography (OCT) to visualize polymerization shrinkage stress in real-time, and the conclusions are shocking.
It is clear, through a variety of well-documented research, that polymerization shrinkage stress in adhesive dentistry is and never will be a good thing. Polymerization shrinkage causes gap formation at the dentin interface which can lead to post-operative sensitivity, leakage, and recurrent decay over time.
The free flow of ideas and opinions in society is crucial to growth and progress, and this is especially true in the dental profession. A responsible clinician should vet and critique all information from researchers, lecturers, and “Key Opinion Leaders” alike to best discover what is best for patients.
Though the internet has made this process increasingly difficult in recent years, self-promotion and willful ignorance can be easily identified and scrutinized, and it is our duty to do exactly that.
To learn more about science-driven Biomimetic Restorative Dentistry, visit www.practicalbrd.com.