MDS PREP
Which of the following permanent maxillary molar teeth normally has four root canals?
1. First molar
2. Second molar
3. Third molar
4. None of theabove
Dental Anatomy
Answer: 1
permanent maxillary First molar teeth normally has four root canals
The primary canine is usually exfoliated between the ages of
1. 5 and 6 years
2. 10 and 11 years
3. l3 and l4years
4. 8 and 9years
Dental Anatomy
Answer: 2
The primary canine is usually exfoliated between the ages of 10 and 11 years
When calcospherites fail to fuse during calcification of dentin matrix then
1 Interglobular dentin is formed
2 Dead tracts are found in formed dentin
3 Irregular dentin results
4 None
Dental Anatomy Answer: 1
Interglobular Dentin:
Sometimes, mineralization of dentin begins in small globular areas that fail to coalesce into a homogenous mass. This results in zones of hypomineralization between the globules.
These zones are known as globular dentin or interglobular spaces. Thus, demonstrating defect of mineralization and not of matrix formation, the dentinal tubules pass uninterruptedly through interglobular dentin.
If a 4th root canal is present in a maxillary 1st molar, it will likely be located in which of the following roots?
1) Mesiolingual
2) Mesiobuccal
3) Distolingual
4) Distofacial
Dental Anatomy Answer: 2
Well over 50% of maxillary 1st molars have two canals in the mesiobuccal root. Some authors cite the number as high as 90%.
There are usually 3 roots and 4 canals in a maxillary 1st molar.
The fourth canal, the mesiolingual canal, is also referred to as: the accessory mesiobuccal canal, mesiocentric, mesiopalatal canal or MB2.
It is usually tough to find MB2 through clinical inspection and it is not obvious on a radiograph. A dentist should expect it is present before beginning a root canal on the first maxillary molar.
The cricothyroid artery is a branch of the
1. occipital artery
2. superior thyroid artery
3. facial artery
4. superficial temporal artery
Anatomy
Answer: 2
The cricothyroid artery is a branch of the superior thyroid artery
The largest resting membrane potential is observed in
1. skeletal muscle
2. smooth muscle
3. equal in both
4. -120 mv in resting smooth muscle
Anatomy
Answer: 1
The largest resting membrane potential is observed in skeletal muscle.
Resting membrane potential (RMP) is the electrical potential difference across
the membrane of a cell when it is not undergoing an action potential or a
similar excitation. It is crucial for the functioning of excitable cells, such
as neurons and muscle cells, as it is the basis for the transmission of
electrical signals. The RMP is primarily determined by the concentration
gradients of ions across the cell membrane and the permeability of the membrane
to those ions.
In skeletal muscle cells, the resting membrane potential is typically around -90
millivolts (mV). This relatively high negative value is due to the higher
concentration of potassium ions (K+) inside the cell compared to the outside,
and the lower concentration of sodium ions (Na+) inside the cell compared to the
outside. The cell membrane is more permeable to K+ than to Na+ at rest, which
allows K+ to leak out through potassium channels and sets up the resting
membrane potential.
Smooth muscle cells, on the other hand, have a resting membrane potential that
is generally less negative than that of skeletal muscle cells. The typical RMP
in smooth muscle cells ranges from -40 to -70 mV, which is closer to the
threshold for depolarization and makes these cells more responsive to stimuli
that could cause contraction. The difference in RMP between smooth and skeletal
muscle is due to variations in ion channel expression and the activity of ion
pumps, which control the ionic composition of the intracellular and
extracellular environments.
To summarize:
1. Skeletal muscle cells have a resting membrane potential of approximately -90
mV.
2. Smooth muscle cells have a resting membrane potential that is generally more
positive than skeletal muscle cells, typically ranging from -40 to -70 mV.
9 months of age, is the usual eruption time for
1. primary mandibular canines
2. primary maxillary canines
3. primary maxillary first molars
4. primary lower lateral incisors
Dental Anatomy
Answer: 4
9 months of age, is the usual eruption time for primary lower lateral incis
The beginning of active eruption of a human tooth occurs
1. before the root has begun to develop
2. coincidental with the beginning of root formation
3. before the root has begun to develop
4. after one half of the root is formed
Dental Anatomy
Answer: 4
The beginning of active eruption of a human tooth occurs after one half of the root is formed