Comparative Assessment of Contact Osteogenesis at the Titanium Implant-Bone Junction in Male Rabbits with Dissimilar Femoral Defects / Evaluación Comparativa de la Osteogénesis de Contacto en la Unión entre el Hueso y el Implante de Titanio en Conejos Macho con Defectos Femorales Diferentes

SUMMARY: Traumatized bone tissue has the capacity to repair itself so that it eventually regains its almost original form, even in the case of artificially inserted implants. The process that stays at the base of the regeneration is represented by osteogenesis or remote osteogenesis. The major difference between the two types of bone formation is the location of the cement line, which is located on the surface of the implant for contact osteogenesis and on the surface of the bone defect for remote osteogenesis. The aim of the present study was to assess the contact osteogenesis in the case of inserted titanium screws in holes with diameters of 1.8 mm and 1 mm respectively. The obtained results show, in the case of the groove with 1.8 mm that the newly proliferated bone represents 73.85 % of the total area, while in the case of the groove with 1 mm in diameter the value of the newly proliferated bone is 26.15 %. In conclusion, the insertion of titanium screws by self-tapping into the hole smaller than the core of the screw is accompanied by bone proliferation by contact osteogenesis much more modest than in the case of insertion into the hole larger than the core of the screw.

El tejido óseo traumatizado tiene la capacidad de reparar en forma espontánea, de modo que eventualmente recupera su forma casi original, incluso en el caso de implantes insertados artificialmente. El proceso que queda en la base de la regeneración está representado por la osteogénesis u osteogénesis a distancia. La principal diferencia entre los dos tipos de formación ósea es la ubicación de la línea de cemento, que se encuentra en la superficie del implante para la osteogénesis de contacto y en la superficie del defecto óseo para la osteogénesis remota. El objetivo del presente estudio fue evaluar la osteogénesis de contacto en el caso de tornillos de titanio insertados en forámenes con diámetros de 1,8 mm y 1 mm respectivamente. Los resultados obtenidos muestran, en el caso del surco de 1,8 mm que el hueso neoproliferado representa el 73,85 % del área total, mientras que en el caso del surco de 1 mm de diámetro el valor del hueso neoproliferado es del 26,15 %. En conclusión, la inserción de tornillos de titanio por autorroscantes en el foramen menor que el núcleo del tornillo se acompaña de una proliferación ósea por osteogénesis de contacto mucho más modesta que en el caso de la inserción en el foramen mayor que el núcleo del tornillo.

The utility of histopathologic examination in appreciation of mandibular osteoporotic status.

The study was performed on 14 female patients aged between 54 and 83 years, presented for insertion of mandibular implants and diagnosed with systemic osteoporosis on DXA. Radiological examination showed no striking maxillar bone rarefactions or changes in the mandibular cortex form that allows the diagnosis of osteoporosis at the jaw. To obtain informations on the health status of mandibular bone in these patients, we considered it appropriate to do histopathological investigations on fragments of bone harvested from implant insertion area. To this end, fragments of bone harvested when performing the new alveolus were fixed in Stieve mixture, decalcified with trichloroacetic acid and included in paraffin. Five-micrometer thick sections were stained with Goldner's Trichrome method and examined microscopically. Histopathology revealed changes of different intensity in the organic and vascular components of the mandibular bone, in all patients studied, with differences from case to case. Thus, confirming that patients with systemic osteoporosis diagnosed by DXA at the femoral neck and/or the vertebrae have histological changes in the mandibular bone, but the extent of damage is different. Providing detailed information about organic component and bone vascularization, crucial components in the early stages of osseointegration, histopathology is more useful for assessing mandibular osteoporotic status, compared with methods of investigation that aim only the mineral component, mineralization being the final stage of osseointegration. Highlighting mandibular osteoporotic early lesions by histopathological examination allows a patient-specific therapeutic approach and could be an accurate method of assessment for required osseointegration period, depending on the degree of impairment.