Zirconium is one of the dental materials with the highest fracture resistance; however, bruxism patients apply uncontrolled and jarring forces, 5-10 times greater than normal chewing (approximately 400-800 kg), when clenching their jaws at night. If zirconium crowns are made using traditional porcelain overlay techniques, these excessive horizontal friction forces cause the porcelain layer on top of the zirconium to flake off and chip. If made of pure monolithic zirconium, the crown may not chip; however, this enormous load is then directly transferred to the natural teeth in the opposing jaw, causing them to wear down, the root of the abutment tooth under the crown to crack, or permanent damage to the temporomandibular joint (TMJ). To prevent this destructive cycle and protect the crowns, the use of a rigid acrylic night guard after treatment is absolutely essential for bruxism patients.
