Utility of measuring anterior-posterior spread to determine distal cantilever length off a fixed implant-supported full-arch prosthesis: A review of the literature.

BACKGROUND Historically, anterior-posterior (AP) spread assessments were often used to determine the length that a distal cantilever could be extended off an implant-supported fixed full-arch prosthesis. TYPES OF STUDIES REVIEWED The authors searched the literature for articles that used AP spread to calculate cantilever size to be constructed off implants bearing a fixed implant-supported full-arch rehabilitation. RESULTS The data indicate that the relationship between AP spread and cantilever length is not linear and many influences (such as beam theory, cantilever size differences in the mandible versus maxilla, number and distribution of placed implants, prosthetic materials, and framework design) need to be considered when computing cantilever length with respect to fixed implant-supported prostheses. PRACTICAL IMPLICATIONS Recommendations using AP spread assessments to compute cantilever lengths have not been validated by means of prospective scientific evaluations. Therefore, AP spread evaluation is just one of many issues that need to be considered when determining distal cantilever length associated with a fixed full-arch implant-bearing prosthesis.