UCLA abutment substand: a colloquial term used to describe a dental crown that is attached directly to the implant body by means of a screw without an intervening abutment
ultimate strength : the greatest stress that may be induced in a material at the point of rupture—called also ultimate tensile strength
ul·tra·vi·o·let: radiant energy of wavelengths shorter than extreme violet and lying beyond the ordinarily visible spectrum. Usually assigned to wavelengths shorter than 380 nm
1un·der·cut 1: the portion of the surface of an object that is below the height of contour in relationship to the path of placement 2: the contour of a cross-sectional portion of a residual ridge or dental arch that prevents the insertion of a dental prosthesis 3: any irregularity in the wall of a prepared tooth that prevents the withdrawal or seating of a wax pattern or casting
2un·der·cut : to create areas that provide mechanical retention for materials placement
uniform color space : color space in which equal distances are intended to represent threshold or above threshold perceived color differences of equal size
u·ni·lat·er·al : relating to one side; one-sided
unilateral partial denture: see UNILATERAL REMOVABLE DENTAL PROSTHESIS
unilateral removable dental prosthesis : a removable dental prosthesis which restores lost or missing teeth on one side of the arch only
unilateral subperiosteal implant : an eposteal dental implant that provides abutments for support of a removable or fixed dental prosthesis in a partially edentulous arch
unstrained jaw relation : 1: the relation of the mandible to the skull when a state of balanced tonus exists among all the muscles involved 2: any jaw relation that is attained without undue or unnatural force and that causes no undue distortion of the tissues of the temporomandibular joints (GPT-4)
upper impression slang: see MAXILLARY IMPRESSION
up·right : the movement of a tooth into an erect or normal position
