There are rare cases of impacted permanent central incisors with dilaceration, a dental deformity characterized by pronounced angulation of the longitudinal tooth axis. This paper presents the orthodontic alignment of a permanent maxillary left central incisor in a 7.5-year-old boy, which appeared impacted radiologically and displayed root dilaceration. Following surgical exposure with the closed-eruption technique and appropriate orthodontic traction, the tooth was successfully aligned into the dental arch and the root was radiologically shown to be straightened and relatively well developed.
Clinical studies have established that NaF increases mineral content in bone, although the cellular mechanisms underlying its osteoinductive effects remain unclear. Because metabolic effects of fluoride have been linked to ion flux and alterations in membrane potential, we used patch-clamp recording techniques to examine the electrophysiological response of osteoblastic cells to NaF. In these experiments, we show that NaF increased the amplitude and P(open) of a 73 pS potassium-selective ion channel. The effect of NaF depended on extracellular Ca2+ and could be blocked by a combination of calcium-channel blocking agents, suggesting that potentiation of channel activity was dependent on external calcium. Because all patches were in the cell-attached configuration, the effect of NaF was presumable indirect. Although the underlying cellular mechanisms remain unclear, our findings suggest that activity of calcium and/or potassium-selective channels via second messenger cascades may mediate many of the early events involved in the response of bone cells to inorganic fluoride.
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