A hard night guard is a custom - fitted oral appliance meticulously crafted to safeguard teeth against bruxism, the involuntary grinding and clenching of teeth that occurs during sleep. Constructed from robust materials such as rigid acrylic or thermoplastics like poly(methyl methacrylate) (PMMA), these guards typically measure 2 - 4 mm in thickness. This specific thickness is designed to absorb masticatory forces that can soar as high as 200 - 400 N, effectively preventing enamel erosion, tooth fractures, and reducing jaw muscle fatigue. In contrast to soft guards, hard night guards retain their shape even under continuous pressure, making them the preferred choice for individuals suffering from severe bruxism.
Dentists typically fabricate hard guards via impressions or 3D scans, with CAD/CAM milling ensuring precise adaptation to dental arches. Their smooth occlusal surfaces guide natural jaw alignment, reducing temporomandibular joint (TMJ) stress. Clinical studies show hard guards can decrease occlusal forces by 60 - 80%, outperforming soft guards in long - term durability. Maintenance involves daily brushing with mild soap and storing in a ventilated case to prevent bacterial growth.
Caution is advised: improper fitting may cause bite misalignment or gum irritation. Users should replace guards every 3 - 5 years as materials wear or dental structures change. While over - the - counter options exist, professional customization is recommended to balance protection and comfort, making hard night guards a cornerstone in bruxism management.