Full-coverage bite guards increase clenching activity for some patients by providing an ideal clenching NTI-tss Plus is made from Keller's Clear 450 is now ChairsideSplint.com, new home of the NTI-tss ® NTI-tss Plus | Snoring & Sleep Apnea . The NTI-tss Plus is an FDA approved dental The NTI is a small thermoplastic night guard that fits comfortably on Keller is an industry leader in providing bite guard solutions, including the NTI-tss Plus, approved for the treatment of obstructive sleep apnea and snoring.