Immediate loading of orthodontic mini-implants: a histomorphometric evaluation of tissue reaction.
Although immediate loading of orthodontic mini-implants can be clinically successful, a lack of histological data exists. The present investigation was performed to evaluate, in an animal model, tissue reaction to immediate loading. Fifty orthodontic titanium mini-implants were inserted in four adult male monkeys at four time intervals. Forty-two devices were loaded with 50 cN super-elastic coil springs immediately after insertion while eight were left unloaded and served as the controls. After euthanasia, the following histomorphometric parameters were evaluated: bone volume (BV/TV), bone-to-implant contact (BIC), mineralizing surface (MS/BS), and erosion surface (ES/BS). Statistical analysis was performed by means of non-parametric tests. Four devices were removed because of loss of stability. A wide variation between animals was found for all parameters. BV/TV: slightly higher values were found in the unloaded sample. Although no particular trend was observed, at 3 months higher values were found in the lower jaw. BIC: a trend to a decrease between 1 week and 1 month followed by a significantly progressive increase was observed. Implants that showed some sections with as little as 3 per cent BIC successfully resisted loading. MS/BS: higher values were found in the lower jaw. MS/BS increased significantly between 1 week and 1 month, followed by a progressive decrease. ES/BS: there was a decrease between 1 week and 1 month, followed by a progressive re-increase. BV/TV did not show any particular trend while BIC was a time-dependent factor. MS/BS and ES/BS demonstrated opposite trends during the healing period. Immediate loading with light forces did not negatively affect the bone healing pattern.
Luzi
Cesare
C
Department of Orthodontics, School of Dentistry, University of Aarhus, Denmark. cesare.luzi@gmail.com
Verna
Carlalberta
C
Melsen
Birte
B
D000818:Animals; D015519:Bone Density / Q000502:physiology; D001862:Bone Resorption / Q000503:physiopathology; D001863:Bone Screws; D002113:Calcification, Physiologic / Q000502:physiology; D008252:Macaca fascicularis; D008297:Male; D008334:Mandible / Q000473:pathology*; D008437:Maxilla / Q000473:pathology*; D023421:Models, Animal; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D009969:Orthodontic Wires; D016348:Osseointegration / Q000502:physiology; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors