HNK1 and Sox10 are present during repair of mandibular bone defects.

Neural crest cells possess characteristics of stem cells including plasticity and ability to differentiate into various cell types. HNK1 and Sox10 are markers of neural crest cell progenitors that have been demonstrated in osteoblasts during osteogenesis of the maxilla and mandible. We investigated the presence of Sox10 and HNK1 during regeneration of mandibular bone defects. Defects were created in mandibles of rats. Samples of these defects were collected at 7, 14 and 28 days post-surgery; bone regeneration was observed during this period. Immunohistochemical analysis revealed expression of HNK1 and Sox10 in osteoblasts, osteocytes and osteogenic cells, whereas osteoclasts were unstained. HNK1 expression was increased in osteoblasts and osteocytes over time and SOX10 expression was found in osteoblasts and osteogenic cells at 7, 14 and 28 days post-surgery. HNK1 and Sox10 are present in osteoblasts, osteocytes and osteogenic cells during mandible bone regeneration.

Morphometric analysis of shank-to-flute ratio in rotary nickel-titanium files.

AIM: To evaluate the shank-to-flute ratio in rotary nickel-titanium (Ni-Ti) instruments. METHODOLOGY: The cutting portion of 15 size 30 Ni-Ti rotary instruments, ProFile.04, ProFile.06, Pow R.02, Pow R.04 and Quantec series 2000, were examined. The handles of the instruments were fixed to a bench and supported by a removable resin base. The cutting portion was then manually abraded with abrasive strips along one aspect of their length. All instruments were fixed in a stub that permitted the adaptation and inspection of six instruments at the same time. A scanning electron microscope (SEM; Phillips model XL 20; Eindhmoven, the Netherlands) at x60 magnification was used to collect cross-sectional measurements of the shank and the flutes at the first, third and fifth flutes from the tip. The software autocad 2000 was used to measure these areas. RESULTS: The shank percentage value was, on average, equal to or greater than the flute percentage value at the sites analyzed. A regular and proportional pattern of increase of shank and flute measurements, as well as the ratio between them, was preserved. There was no significant difference between instruments and between flute sites on the same instrument (P > 0.05). However, the Quantec instruments had a flute area twice the flute area of the other instruments. CONCLUSIONS: The instruments had a shank percentage measurement value equal to or greater than the flute percentage value; the cross-sectional shank-to-flute ratio was preserved. The instruments had similar shank areas, but the flute area of the Quantec instruments was twice their shank area; i.e. the design of the Quantec files provides longitudinal reinforcement by means of a gain in flute area.