The posterior tooth that gives a better support is:

# The posterior tooth that gives a better support is:
a) With convergent roots
b) Divergent roots
c) Conical roots
d) Curved roots

The correct answer is B. Divergent roots.

- Roots with greater labiolingual width than mesiodistal width are preferable to roots that are round in cross section.

• Long, irregularly shaped and divergent roots offer great support.

• Short, conical and blunted roots offer poor support.

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Functional cusp Bevel

# The functional cusps are bevelled in the preparation of posterior cast crowns:
a) To reduce the stress at the line angles
b) To prevent the fracture of the tooth structure
c) For the structural durability of the restoration
d) To help in the retention

Bevelling of the functional cusp (lingual inclines of maxillary lingual cusps and the buccal inclines of mandibular buccal cusps) is an integral part in obtaining the structural durability of the restoration.

- Lack of functional cusp bevel can cause:

• A thin area or perforation on the casting.

• Overcontouring and poor occlusion of the restoration.

• Loss of tooth structure and retention.

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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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