Silicon Nitride Coatings on Dental and Orthopedic Implants: A Systematic Review of Preclinical Studies

Background: Silicon nitride is an established bulk ceramic in spinal fusion, but a coating can delaminate, dissolve or wear through, and preclinical evidence on coatings has not been synthesized. Methods: Databases and trial registries were searched in October 2026. Eligible studies were in vitro, bench or animal studies of silicon nitride coatings on implant substrates. Risk of bias was assessed with tools for animal and laboratory studies; the synthesis was narrative. Results: Of 476 records screened, 44 publications from 19 research groups were included (18 films, seven doped or graded films, 19 composites). Counted descriptively, 21 of 27 cell studies and 12 of 13 bacterial studies favored a coating, but came from only nine and five groups and did not measure effect size. In one bench series of sputtered coatings on cobalt–chromium, wear in serum was similar to bulk silicon nitride for all but one coating; adhesion and dissolution remained concerns. Six animal studies, from two groups, reported more bone with a coating; the one comparison with hydroxyapatite favored hydroxyapatite. All had moderate risk of bias by a descriptive rule. Conclusions: The evidence is preclinical, short-term and clustered in few groups, and does not establish the long-term stability of coated implants.