FEI-SEM-investigation of the in situ formed pellicle

Introduction: The aim of the study was to examine the contribution of secretory immunoglobulin A (sIgA), mucine 1, carbonic anhydrase 1 & 2 and lysozyme in the in situ formed pellicle to make progress in decoding the complex mechanisms concerning intraoral bacterial adherence and biofilm formation using high resolution scanning electron microscope (FEI-SEM). Material and methods: Two healthy subjects were chosen for in situ pellicle formation experiments. Enamel specimens were mounted buccally and palatally in the region of the upper first molars onto the acrylic splints using a vinyl polysiloxane impression material. Time of intraoral exposure was 30 or 120 min, respectively. The detection of sIgA, mucine 1, carbonic anhydrase 1 & 2 and lysozyme took place by gold-immunolabeling. Specimens were then fixed and dehydrated in an ascending ethanol series and submitted to critical point drying. Before FEI-SEM investigation enamel slabs were mounted on stubs and coated with evaporated carbon. The micrographs were taken in an FEI-SEM at a standard magnification of 80,000-fold and SEI and BEI detectors. Results: The results of the FEI-SEM investigation indicate that the analysed proteins were randomly distributed onto the pellicle surface without any preferential localization. They might be considered as potential receptors for bacterial adherence as well as structural components that are even involved in the early stages of pellicle formation. Conclusion: The high resolution immunohistochemical approach allowed us to define three-dimensional features of the oral pellicle and to reveal the distribution of specific components that may function as receptor for bacterial adherence.