title: Primary stability, insertion torque, and bone density of conical implants with internal hexagon: is there a relationship?
abstract: Between implants and peri-implant bone, there should be a minimum gap, without micromotions over a threshold, which could cause resorption and fibrosis. The higher the implant insertion torque, the higher will be the initial stability. The aim was to evaluate in vitro the correlation between micromotions and insertion torque of implants in bone of different densities. The test was performed on bovine bone of hard, medium, and soft density: 150 implants were used, 10 for each torque (20, 35, 45, 70, and 100 N/cm). Samples were fixed on a loading device. On each sample, we applied a 25-N horizontal force. Insertion torque and micromotions are statistically correlated. In soft bone with an insertion force of 20 and 35 N/cm, the micromotion resulted significantly over the risk threshold, which was not found with an insertion force of 45 and 70 N/cm and in hard and medium bones with any insertion torque. The increase in insertion torque reduces the amount of micromotions between implant and bone. Therefore, the immediate loading may be considered a valid therapeutic choice, even in low-density bone, as long as at least 45 N/cm of insertion torque is reached.
authors.affiliation: Department of Stomatology and Oral Sciences, University "G. D'Annunzio" of Chieti, Chieti, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Trisi
authors.forename: Davide
authors.initials: D
authors.lastname: Berardi
authors.forename: Michele
authors.initials: M
authors.lastname: Paolantonio
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Spoto
authors.forename: Antonio
authors.initials: A
authors.lastname: D'Addona
authors.forename: Giorgio
authors.initials: G
authors.lastname: Perfetti
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D015519:Bone Density / Q000502:physiology*; D002417:Cattle; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention; D003799:Dental Stress Analysis / Q000295:instrumentation; D008422:Materials Testing; D013314:Stress, Mechanical; D019415:Torque
chemical_list: D015921:Dental Implants