Sublingual Space vs Submandibular Space

# Sublingual space is divided from submandibular space by:
a) Fibres of mylohyoid
b) Submandibular gland
c) Body of mandible
d) Geniohyoid

The correct answer is A. Fibres of Mylohyoid.

The mylohyoid muscle, which forms the floor of the oral cavity, is the key to the diagnosis and surgical management of the infections of the sublingual and submandibular spaces. The submandibular space is separated from the overlying sublingual space by the fibers of the mylohyoid muscle.

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Cavernous Sinus Thrombosis

# Cavernous sinus thrombosis following infection of anterior maxillary teeth most often from spread of infection along:
a) Facial artery
b) Angular artery
c) Ophthalmic vein
d) Pterygoid plexus

The correct answer is C. Ophthalmic vein.

Cavernous thrombosis (CST) is the infectious thrombosis of the cavernous sinus, which is a dural venous space present in the middle cranial fossa on either side of the sella turcica.

• It is a paired sinus, anterior and posterior. Infections to cavernous sinus may spread by two

pathways.

• The anterior route composed of ophthalmic veins and their anastomosis with the facial vein;

the angular vein; the infraorbital vein; and the inferior palpebral vein; readily allows the invasion of the cavernous sinus. Spread of infection by this pathway presents the classic picture of a fulminating cavernous .sin us thrombosis and CST through this route is more common than posterior route.

• The pterygoid venous plexus, which constitutes the posterior route, provide a connection between cavernous sinus and the retromandibular vein.

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Types of Maxillary Major Connectors

TYPE	IMPORTANT FEATURES
Single palatal bar	• Palatal connector component of less than 8mm in width is referred to as a bar • It is the least logical of all palatal connectors • To maintain rigidity it has to be made bulky • Derives least support from the palate .
Palatal strap	• It has suitable rigidity without excessive bulk • Its width should be increased as the edentulous span increases in length . • It is best suited for short span, tooth supported edentulous areas .
Anteroposterior Palatal Bar (double palatal bar)	• In comparison to the amount of soft tissue coverage, it is by far the most rigid palatal major connector • It is indicated in the presence of a torus that is not to be removed . • Anterior bar is narrower than the width of palatal strap. • Posterior bar is half oval; its width is equal to single palatal bar but less. bulky . • Derives least support from the bony palate • Not indicated in high narrow palatal vault and if the remaining teeth are periodontally weak
Anteroposterior Palatal Strap (Closed horse shoe)	• It is indicated in almost any maxillary partial denture design . • Structurally it is the rigid palatal major connector . • The anterior border should be located posteriorly in the valleys between the rugae crests . • Posterior border located at junction of hard and soft palates . • It is the best designed palatal major connector.
U shaped or Horse Shoe shaped	• Least desirable palatal major connector . • Poorest designed palatal major connector because it lacks rigidity • This is indicated only in cases of inoperable tori extending to the posterior limit of t he hard palate . • It lacks rigidity • This design leads to increased flexibility and movement at the open ends . • The wider the coverage, the more it resemble a complete palate (palatal plate)
Complete Palate (Palatal plate)	• It is the major connector that provides greatest retention . • Due to accuracy and stability of the cast metal, posterior palatal seal is not necessary. • The posterior border extends to the junction of the soft and hard palate . • It is indicated when anterior or posterior teeth are to be replaced bilaterally .

Stress breaker in Partial Dentures

# Disadvantage of using a stress breaker in partial dentures is:
a) The partial denture becomes cumbersome
b) Ridge resorption occurs
c) Its is not economical
d) No disadvantages present

The correct answer is B. Ridge resorption occurs.

Stress breaker or equalizer is a device that allows some movement between the denture base and the direct retainer. This type of design protects the vulnerable abutment teeth and concentrates more stresses on the residual ridge.

Its disadvantages are:

• Increased residual ridge resorption

• Difficulty to fabricate and repair

• Less tolerated by the patient

• The need for frequent relining

• High cost

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Guiding planes in RPD

# Guiding plane in RPD should be located at:
a) In between edentulous space
b) Abutment surface adjacent to an edentulous area
c) Edentulous areas
d) Abutment area

The correct answer is: B. Abutment surface adjacent to an edentulous area. 

Guiding planes are surfaces on proximal or lingual surfaces of teeth that are parallel to each other and, more importantly, to the parts of insertions and removal of a removable partial denture. These planes may be created on enamel surfaces or on the surfaces of dental restorations.

The function of guiding planes are as follows:

• To provide one path of placement and removal of restoration.

• To ensure the intended actions of reciprocal, stabilizing and retentive components.

• To eliminate gross food traps between abutment teeth and components of the denture.

As a rule, proximal guiding plane surfaces should be about one half the width of the distance between the tips of adjacent buccal and lingual cusps or about one third of the buccal lingual width of the tooth. They should extend vertically about 2/3rds of the length of enamel crown portion of the tooth from the marginal ridge cervically.

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Dental Surveyor

# Dental surveyor is used to:
a) Measure resiliency of tissues
b) Indicate relative parallelism between two teeth
c) To determine primary stress bearing area
d) To determine the depth of undercut

The correct answer is D. To determine the depth of undercut.

 - Surveyor is used to determine the relative parallelism of two or more surfaces of teeth or other parts of dental cast. It is used to:
• Survey the diagnostic and master cast
• Contour wax patterns and crowns
• Measure specific depth of undercut
• Blocking out the master cast
• Place internal rests etc.

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Advantage of resin teeth over porcelain teeth

# The advantage of resin teeth over porcelain teeth is:
a) Greater wear resistance
b) Increased hardness
c) Better dimensional stability
d) Greater impact resistance

The correct answer is D. Greater Impact resistance.

Resin teeth display greater impact resistance and ductility and are less likely to chip or fracture when compared to porcelain.

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