Early cortical bone healing around loaded titanium implants: a histological study in the rabbit.
OBJECTIVE
To identify the role of immediate implant loading on the early phases of the bone healing responses.


METHODS
Implants were placed in rabbit tibial diaphyses and left to heal for 3, 7, 14, 28 or 42 days. Half of the animals received an immediate loading protocol of 2.2 N at 3 Hz for 1800 cycles and 5 days/week, whereas the others served as unloaded controls. Histological assessment was combined with histomorphometrical measurements.


RESULTS
At early time-points, an endosteal and periosteal new bone formation was found, while the cortex itself contained damaged osteocytes. At later time-points, new bone formation was also found at the cortical level itself. Differences between groups were found mainly in this new bone formation process, with larger reactions for the endosteal and periosteal bone in the loaded group after 28 and 42 days, respectively. At the end-point of the experiment, bone formation at the cortical level was reduced in the loaded group compared with the control group.


CONCLUSIONS
These results show that the immediate loading protocol caused no differences in the sequential events leading to osseointegration in cortical bone. However, the processes of new bone formation originating from the endosteum and the periosteum lasted longer compared with the unloaded controls.
Slaets
Elke
E
Department of Prosthetic Dentistry, BIOMAT Research Group, K.U., Leuven, Belgium.
Naert
Ignace
I
Carmeliet
Geert
G
Duyck
Joke
J
D000497:Alloys; D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry; D015519:Bone Density / Q000502:physiology; D016723:Bone Remodeling / Q000502:physiology; D001863:Bone Screws; D003722:Dental Alloys / Q000737:chemistry*; D015921:Dental Implants; D018483:Diaphyses / Q000473:pathology / Q000601:surgery; D023421:Models, Animal; D016348:Osseointegration / Q000502:physiology; D010006:Osteoblasts / Q000473:pathology; D010010:Osteoclasts / Q000473:pathology; D010011:Osteocytes / Q000473:pathology; D010012:Osteogenesis / Q000502:physiology; D010521:Periosteum / Q000473:pathology; D011817:Rabbits; D011897:Random Allocation; D013314:Stress, Mechanical; D013499:Surface Properties; D013977:Tibia / Q000473:pathology / Q000601:surgery*; D013997:Time Factors; D014025:Titanium / Q000737:chemistry*; D014945:Wound Healing / Q000502:physiology
D000497:Alloys; D001672:Biocompatible Materials; D003722:Dental Alloys; D015921:Dental Implants; C031462:titanium alloy (TiAl6V4); C009495:titanium dioxide; D014025:Titanium