Forces acting through FPD on Abutment tooth

# The forces acting through a fixed partial denture on the
abutment tooth should be directed:
a) As far as possible at right angles to the long axis of the teeth
b) Parallel to the long axis of the teeth
c) By decreasing the mesio-distal dimension
d) None of the above

The correct answer is B. Parallel to the long axis of the teeth/

Ideally, the forces acting on the abutment tooth should be parallel to long axis of the tooth and should be within the confines of the root. By this, the stress is directed vertically which is well tolerated by the periodontium. Narrowing the buccolingual width of occlusal surfaces of the constructed crowns help to achieve these desirable forces.

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Ultrasonic instruments contraindications

# Ultrasonic instruments are indicated for each of the following types of patients EXCEPT one. Which is the EXCEPTION?
A. Active infectious disease
B. Deep periodontal pockets
C. Controlled diabetic
D. Edematous tissue
E.Mildly uncontrolled diabetic

Ultrasonic instruments should NOT be used
for patients with active infectious disease
because the aerosol created by the instruments serves to spread the infection
around the operatory.

Diabetes and deep periodontal pockets are
indications that ultrasonic instrumentation.

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Full thickness Flaps

# Each of the following is associated with
full-thickness flaps EXCEPT one. Which is the EXCEPTION?
A. Periosteum stays on the bone
B. Apical repositioning
C. Osseous recontouring
D. Dissection of the tissue with a blunt instrument

The correct answer is A. Periosteum stays on the bone. 

A full thickness flap includes stripping all of

the soft tissue (epithelium, connective

tissue, periostuem) from the bone.

Following placement of the incisions, the

flap is dissected using blunt instruments

like a # 9 molt to separate the soft tissue

from the bone.

Full thickness flaps are used when

recontouring the osseus structures below

or when the gingiva are repositioned

apically.

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Sharpening Dental Hand Instruments

# When sharpening instruments, the ______ of the blade should be placed at an angle ________ to the sharpening stone.
A. Bevel, 90
B. Bevel, 45
C. Working end, 45
D. Working end, 90°

The correct answer is B. Bevel, 45

When sharpening an instrument, the bevel
of the blade is placed at an angle of 45° to
the sharpening stone. This ensures
maximum efficiency of the blade to sharpen the instrument.

Instrument sharpening is an important
aspect of operative dentistry. Dull
instrument are not recommended for
carrying out procedures in the oral cavity.

Dull instruments are prone to produce more heat, are less efficient and can damage tooth structure. It is recommended to  discard those instruments which cannot be sharpened.

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Four handed Dentistry

# When utilizing four-handed dentistry, the assistant should be positioned...
A. Higher than the dentist to facilitate visibility
B. Different positions depending on where the dentist is working
C. Lower than the dentist for ergonomic posturing
D. At the same height because they are a team

The correct answer is A. Higher than the dentist to facilitate visibility.

In four handed dentistry, the assistant
should sit close to the back of patient's
chair higher than the dentist to facilitate
visibility.

This position is suitable for better view of
the site, instruments and materials from the
mobile cart or instrument tray. It also allows you access to these materials without leaning or overextending your arms.

Assistant stools should be placed in a
position so that their eye level is 4 to 6
inches higher than the dentist's.

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Dental Anomaly Affecting Only posterior Teeth

# Each of the following dental anomalies is likely to affect anterior teeth EXCEPT one. Which is the EXCEPTION?
A. Concrescence
B. False microdontia
C. False macrodontia
D. Gemination
E. Dens-in-dente

The correct answer is A. Concresence.

Concrescence characteristics:
Involves the union of two or more teeth
through CEMENTUM ONLY.

Most common in the permanent molars.

It is different from fusion, because it
occurs following eruption and never
involves enamel and dentin.

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Life cycle of an Ameloblast - Amelogenesis

# In the life cycle of an ameloblast, there are cells that contain Tomes' processes. The cells described are in which of following stages?
A. Morphogenic
B. Maturative
C. Organizing
D. Secretory
E. Protective

The correct answer is D. Secretory.

Tomes' process are projections or
extensions of ameloblasts formed as the
ameloblast moves away from the
developing enamel matrix.

The ameloblasts secrete secretory granules
needed for the production enamel matrix
during this phase.

Ameloblasts are actively contributing to the
enamel matrix formation by combining the
secretory granules with the glycoprotein to
lay down enamel during the secretory
phase.

Presence of Tomes' processes is a
histological indicator of the secretory
phase.

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