A Mahdee1, J Eastham2, J M Whitworth3, J I Gillespie4. 1. Centre for Oral Health Research, UK; Institute of Cellular Medicine, UK; School of Dental Sciences Newcastle University, UK; University of Baghdad College of Dentistry, Iraq. Electronic address: a.f.mahdee@ncl.ac.uk. 2. School of Dental Sciences Newcastle University, UK. Electronic address: j.e.eastham@ncl.ac.uk. 3. Centre for Oral Health Research, UK; School of Dental Sciences Newcastle University, UK. Electronic address: john.whitworth@ncl.ac.uk. 4. Urology and Urological Rehabilitation Antwerp University, Belgium. Electronic address: james.Gillespie@uantwerpen.be.
Abstract
OBJECTIVE: To re-examine the morphology and potential functions of odontoblasts in intact rat incisors and after cavity preparation into dentine. DESIGN: Intact incisors were fixed, decalcified, snap frozen and sectioned (10μm), before staining with rhodamine phalloidin or antibodies for cyto-skeletal proteins: vimentin and actin, ion transporter: NaK-ATPase, and dendritic cell marker: OX6. Samples with cavity were processed similarly and stained for actin and vimentin before comparing the lengths of odontoblast processes (OP) at baseline, 3h and 24h (n=5 for each group). RESULTS: Actin was expressed through the full length of OP, while vimentin immunoreactivity was not uniform, with 4 distinct regions. OP showed morphological complexity with fine branches emanating within different regions of dentine. Novel actin-positive tree-like OP were identified within predentine which reduced in intensity and length toward the incisal portion of the tooth. Specimens with cavities showed time-dependant pulpal retraction of OP. CONCLUSIONS: Differences in structural antibody expression suggest functional variations in OP within different regions of dentine. The role of actin positive OP in predentine is not known, but could be related to dentine deposition, cellular stability or sensing mechanisms. Cavity preparation into dentine was followed by programmed retraction of OP which could be controlled either mechanically by the spatial limitation of the OP within dentinal tubules or structurally by the presence of vimentin, in addition to actin, in the mid-dentine.
OBJECTIVE: To re-examine the morphology and potential functions of odontoblasts in intact rat incisors and after cavity preparation into dentine. DESIGN: Intact incisors were fixed, decalcified, snap frozen and sectioned (10μm), before staining with rhodamine phalloidin or antibodies for cyto-skeletal proteins: vimentin and actin, ion transporter: NaK-ATPase, and dendritic cell marker: OX6. Samples with cavity were processed similarly and stained for actin and vimentin before comparing the lengths of odontoblast processes (OP) at baseline, 3h and 24h (n=5 for each group). RESULTS: Actin was expressed through the full length of OP, while vimentin immunoreactivity was not uniform, with 4 distinct regions. OP showed morphological complexity with fine branches emanating within different regions of dentine. Novel actin-positive tree-like OP were identified within predentine which reduced in intensity and length toward the incisal portion of the tooth. Specimens with cavities showed time-dependant pulpal retraction of OP. CONCLUSIONS: Differences in structural antibody expression suggest functional variations in OP within different regions of dentine. The role of actin positive OP in predentine is not known, but could be related to dentine deposition, cellular stability or sensing mechanisms. Cavity preparation into dentine was followed by programmed retraction of OP which could be controlled either mechanically by the spatial limitation of the OP within dentinal tubules or structurally by the presence of vimentin, in addition to actin, in the mid-dentine.