Dennis was employed at the Hercules Research Center for 26 years as a scientific glass technologist working with chemists and engineers to create complex glass systems. He has been the Instructional Chair of Scientific Glass Technology at Salem Community College for the last 9 years. Dennis has taught at the Corning Museum Studio and UrbanGlass. He was Chair of Education and Section Director of the American Scientific Glassblowers Society for 7 years. Dennis has greatly enjoyed teaching scientific glass technology, art and glass chemistry at Salem Com Col for over 30 years, assisting energetic people learn the art of glassblowing and has been a great influence on the recent growth of flameworking. Dennis was honored to participate in "Apparatus: The Art of Scientific Glass" The exhibit opened in November 2018 at UrbanGlass. The exhibit was curated by Glenn Adamson and Dennis Briening and installed by Dennis.