Human tooth development is postulated that both models influence tooth development at different times. Other structures that may appear in a developing tooth in this stage are enamel knots, enamel cords, and enamel niche. Hard tissues, including enamel and dentin, develop during the next stage of tooth development. This stage is called the crown, or maturation stage, by some researchers. Important cellular changes occur at this time. In prior stages, all of the IEE cells were dividing to increase the overall size of the tooth bud, but rapid dividing, called mitosis, stops during the crown stage at the location where the cusps of
Smear layer Smear layer The smear layer is a layer of microcrystalline and organic particle debris that is found spread on root canal walls after root canal instrumentation. It was first described in 1975 and much research has been performed since then to evaluate its importance in assisting or preventing the penetration of bacteria into the dentinal tubules. More broadly, it is the organic layer found over all hard tooth surfaces. Early studies of dentinal walls after cavity preparation performed by Brännström and Johnson (1974) showed the presence of a thin layer of debris that was 2 to 5 micrometres thick. In