Tooth Structure Lab Flashcards
Give two reasons why a fissure could increase a tooth’s susceptibility to caries
The fissure is difficult to clean, and becomes a plaque trap.
There is reduced thickness of enamel at the base of the fissure, so a carious lesion can spread rapidly into dentine.
The scalloping found on the enamel-dentine junction (EDJ) is more pronounced in the incisal and cuspal regions, compared with the side of the crown.
Is there any advantage of this arrangement?
Yes
The scalloped junction may provide a better mechanical union between enamel and dentine. There is increased surface of contact. Also, the interlocking shape may provide more resistance to lateral, shearing forces.
This is gnarled enamel.
Is there any functional significance of this type of enamel found in cusps?
Yes
The spatial arrangement of prisms may provide some resilience so that the enamel ‘gives’ very slightly during application of occlusal loads.
What are enamel spindles?
They are thought to be formed by odontoblast processes that extend for a short distance into the internal enamel epithelium layer of the enamel organ
What are enamel tufts?
They represent regions of incompletely mineralised enamel matrix. They extend a short distance from the ADJ.
What are enamel lamellae?
They represent regions of incompletely mineralised enamel matrix. They extend through the full thickness of enamel.
What side of the crystallites is more susceptible to etching?
Side
What can too much etch cause?
Very smooth surface therefore less bonding
What type of dentine is present if the tooth is not fully formed?
Primary only
Speed of primary vs secondary dentine?
Primary = fast
Secondary = slow
What materials can be used for a direct pulp cap?
MTA
Calcium hydroxide
What is primary dentine?
Refers to dentine laid down while the tooth is forming. It is completed when the root apex is fully formed.
What is secondary dentine?
Refers to dentine laid down during the life of the tooth, after the tooth is fully formed.
What is tertiary dentine?
Refers to dentine laid down in response to wear of the overlying enamel and dentine.
These appear dark when viewed under transmitted light. The tubules are empty, and are sealed at the pulpal end by the deposition of tertiary dentine. They are:
Dead tracts
