Lines in enamel Flashcards
What happens as the enamel matrix mineralises
Follows the pattern of matrix deposition, marked by lines in enamel
What are incremental lines in sections of mature enamel a result of
Rhythmic recurring deposition of enamel
What are the 2 types of incremental line
- Short period (cross-striations)
- Long period (enamel striae)
What does a circadian rhythm in enamel formation produce
- Regular, daily cross-striation
- Lines cross enamel prisms at right angles
Describe the striae of Retzius
- Superimposed on the daily incremental lines
- More prominent and less frequent incremental lines
What relation does the enamel striae run to the surface
Prominent lines running obliquely across the enamel prisms
How many cross striations are there running between adjacent striae in enamel
7-9 cross-striations
Why does the striae overlying the cusps and incisal edges not reach the surface
- due to the pattern that enamel is deposited
- surface is reached if there is tooth surface loss
Enamel striae on the sides of the crown
Enamel striae will reach the surface in a series of fine grooves running circumferentially around the crown (The perikymata grooves)
Describe the neonatal line
- Formed at birth and reflects metabolic changes at birth
- Prisms appear to change direction and thickness
- Accentuated incremental lines are also produces by systemic disturbances such as fevers
