title: In vivo evaluation of immediately loaded stainless steel and titanium orthodontic screws in a growing bone.
abstract: The present work intends to evaluate the use of immediate loaded orthodontic screws in a growing model, and to study the specific bone response. Thirty-two screws (half of stainless steel and half of titanium) were inserted in the alveolar bone of 8 growing pigs. The devices were immediately loaded with a 100 g orthodontic force. Two loading periods were assessed: 4 and 12 weeks. Both systems of screws were clinically assessed. Histological observations and histomorphometric analysis evaluated the percent of "bone-to-implant contact" and static and dynamic bone parameters in the vicinity of the devices (test zone) and in a bone area located 1.5 cm posterior to the devices (control zone). Both systems exhibit similar responses for the survival rate; 87.5% and 81.3% for stainless steel and titanium respectively (p = 0.64; 4-week period), and 62.5% and 50.0% for stainless steel and titanium respectively (p = 0.09; 12-week period). No significant differences between the devices were found regarding the percent of "bone-to-implant contact" (p = 0.1) or the static and dynamic bone parameters. However, the 5% threshold of "bone-to-implant contact" was obtained after 4 weeks with the stainless steel devices, leading to increased survival rate values. Bone in the vicinity of the miniscrew implants showed evidence of a significant increase in bone trabecular thickness when compared to bone in the control zone (p = 0.05). In our study, it is likely that increased trabecular thickness is a way for low density bone to respond to the stress induced by loading.
authors.affiliation: Laboratoire des Multimatériaux et Interfaces (UMR CNRS 5615), Faculté d'Odontologie de Lyon, Université de Lyon, Lyon, France ; Hospices Civils de Lyon, Lyon, France.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Gritsch
authors.forename: Norbert
authors.initials: N
authors.lastname: Laroche
authors.forename: Jeanne-Marie
authors.initials: JM
authors.lastname: Bonnet
authors.forename: Patrick
authors.initials: P
authors.lastname: Exbrayat
authors.forename: Laurent
authors.initials: L
authors.lastname: Morgon
authors.forename: Muriel
authors.initials: M
authors.lastname: Rabilloud
authors.forename: Brigitte
authors.initials: B
authors.lastname: Grosgogeat
mesh_terms: D000818:Animals; D001863:Bone Screws; D013193:Stainless Steel / Q000737:chemistry*; D013552:Swine; D014025:Titanium / Q000737:chemistry*
chemical_list: D013193:Stainless Steel; D014025:Titanium