|
Questions
|
Answer
|
|
The muscular
skeleton of the lip is formed by the |
Orbicularis oris
|
|
In the lips, the
skin and oral mucosa are sharply demarcated by the |
Vermillion border
|
|
In the upper lip the
vermillion border, slightly protrudes along the midline to form the |
Tubercle
|
|
The tubercle of the
upper lip is |
Protruded. In lower
lip the corresponding area is depressed |
|
Labiomarginal sulci
delineate the |
Cheeks and lower
lip. A feature that occurs with aging |
|
The groove that
separates the lower lip from the chin is |
Labiomental groove
|
|
The tooth that lie
close to the labial commisure are the |
Maxillary canine and
mandibular first premolar |
|
Modified anterior
oral seal is seen in |
Mouth breathers as
normal lip seal is not observed owing to incompetant lips |
|
A tight or over
reactive lip musculature often causes the |
Retroclined incisor
|
|
What is vestibular
fornix |
The extension of alveolar mucosa in to the lip
and cheek forming a trough. Aka vestibular sulcus mucosa |
|
Mineralized tissues
of teeth |
Enamel; dentin;
cementum. Enamel is ectodermal in origin and rest is ectomesenchymal in origin |
|
Bulk of the teeth is
formed by the |
Dentin
|
|
Compare surface and
subsurface enamel |
Surface enamel is
harder, denser and less porous that subsurface enamel. Hardness and density also decrease from surface. The same is also for occulsal/incsial to cervical margin |
|
How is color of
enamel determined |
It is a birefringent
crystalline material. The crystals reflect light in varying direction. Young enamel appears white owing to complete internal reflection of light with no wavelength internally absorbed. This causes low translucency and white color. With loss of crystals in old age, preferential reflection of yellow color of dentin occurs. |
|
What features
renders enamel fracture resistant |
Enamel has a low
tensile strength and is brittle but has high modulus of elasticity, wavy dentinoenamel junction, that provides good mechanical interlocking and facilitates desipation of forces. Toegther with support of dentin, enamel minimizes the possibility of fracture |
|
Cross section of
enamel crystallites |
Are hexagonal in
shape |
|
Molecular
arrangement of unit cell of enamel crystalline |
A hydroxyl group
surrounded by a uniformly spaced calcium ions, which in turn are surrounded by three similarly spaced phosphate ions. |
|
Replacement of ions
in enamel occurs at |
Carbonate ion in
phosphate or hydroxyl ions; magnesium – calicium ion; fluroide – hydroxyl ion |
|
Enamel proteins are
|
Amelogenins and
non-amelogenins. |
|
Trace of lipid
content in enamel is seen in |
Cross striations,
lines of retzius, hunter-schreger bands, prism sheath and prism core |
Prof. Rooban Thavarajah
Oral and Maxillofacial Pathologist
List