HCl secretion and gastric motility

# Which of the following hormone's action results in HCl secretion and gastric motility?
A. GIP
B. Secretin
C. Gastrin
D. Cholecystokinin

The correct answer is C. Gastrin. 

Gastrin is stimulated by amíno acids and

peptides in lumen, distension. It stimulates

HCl secretion and gastric motility.

Other hormones of gastrointestinal system:

Cholecystokinin: Stimulated by fatty acids,

and amino acids in duodenum. Increases

pancreatic digestive enzyme secretion and

increases bile secretion from the

gallbladder.

Secretin: Stimulated by a low pH in the

duodenum. Increases bicarbonate release

from the pancreases and decreases gastric

motility and gastric acid secretion.

GIP: Stimulated by fat and glucose in the

duodenum. Increases insulin release and

decreases gastric motility and gastric acid secretion.

Viruses capable of causing cell transformation

# Which of the following viruses is NOT capable of causing cell transformation?
A. Retrovirus
B. Herpes virus
C. Hepatitis B virus
D. Human papilloma virus
E. Picorna virus

The correct answer is E. Picorna virus.

Picornavirus is an extremely small, ether-
resistant RNA virus which is not capable of
cell transformation. This virus can cause
several different disease conditions.

Diseases caused by Picornavirus include:
- Poliomyelitis
- Herpangina
- Aseptic meningitis
- Encephalomyocarditis
- Foot-and-mouth disease

Prognosis of a tooth

# Which of the following is the MOST critical factor determining the prognosis of a periodontally involved tooth?
A. Mobility of the tooth
B. Probing depth
C. Amount of attachment loss
D. Presence of furcation involvement

The correct answer is C. Amount of attachment loss.

The amount attachment loss determines
the prognosis of periodontally
Compromised teeth.

Teeth with severe attachment loss and
vertical mobility present a hopeless
prognosis and must be extracted to avoid
infection that may compromise other teeth.
The higher the quantity of attachment, the
better the prognosis.

Elevators are instruments designed to:

# Elevators are instruments that are designed to:
A. Engage the tooth coronal to the cementoenamel junction
B. Retract the crestal gingiva before forceps are used
C. Reflect a full thickness flap before forceps are used
D. Engage the tooth apical to the cementoenamel junction

Elevators are instruments used to elevate
the tooth out of its socket.

Elevators are designed to engage the root
portion of the tooth below the
cementoenamel junction.

Elevators are inserted into the periodontal
ligament space, create more room for tooth
movement, and help elevate the tooth out of its socket.

Most undesirable property of sodium hypochlorite

# Which of the following is the most UNDESIRABLE property of sodium hypochlorite?
A. Tendency to bleach tooth structure
B. Reaction with chelating agents
C. Smell
D. Corrosiveness to endodontic files
E. Toxicity to vital tissue

The correct answer is E. Toxicity to vital tissue.

Sodium hypochlorite in undiluted or
excessive amounts is toxic to vital tissues
and can cause periapical tissue damage
and pain.
Sodium hypochlorite is a good disinfectant
that is used in dentistry as an endodontic
canal irrigant at a diluted concentrations.
Sodium hypochlorite is used often used to
disinfect gutta percha points prior to
placement and obturation of the canal.

First step in cavity preparation

# Which of the following describes the 1st step in cavity preparation according to G.V. Black?
A Retention form
B. Outline form
C. Resistance form
D. Convenience form

The correct answer is B. Outline form.

The 1st step in cavity preparation according
to G V Black is to establish the outline form.
The initial extension or the outline form of
the tooth preparation should be visualized
preoperatively by estimating the extent of
the defect, the preparation form requirements of the amalgam, and the need
for the adequate access to place amalgam
into the tooth.

G.V Blacks various steps of cavity preparation are:
- Establish outline form
- Obtain retention form
- Obtain resistance form
- Obtain convenience form

Least distance between tooth and implant:

# The implant should be positioned at least ____ away from natural tooth:
a) 0.5 mm
b) 1.0 mm
c) 1.5 mm
d) 2.0 mm

The correct answer is C. 1.5 mm.

When the implant is closer than 1.5 mm to an adjacent root of a tooth, the wedge-shaped vertical defect may become a horizontal defect, creating bone loss on the adjacent tooth root. 

Initial vertical bone loss around an implant during the first year of loading varies and ranges from 0.5 to more than 3 mm. this effect is utmost importance because the interseptal bone height in part determines the incidence of presence or absence of interdental papillae between the teeth or implants. As a result, an implant should be at least 1.5 mm from adjacent teeth whenever possible.

Natural tooth roots are often close than 1.5 mm to each other. Therefore the ideal mesiodistal implant size is usually less than the natural root dimension. Most often, the ideal implant diameters used to replace the average size anterior tooth correspond to a 4.2 mm implant for a central incisor and canine, and a 3 to 3.5 mm implant for a lateral incisor.

The two conditions that determine the ideal anterior tooth implant size in the mesiodistal dimension are:

• The ideal diameter most often corresponds to the width of the missing natural tooth, 2 mm below the CEJ.

• In addition, the implant diameter plus 1.5mm on each side should be equal to or less than the mesiodistal dimension between the two natural roots at the level of the crest of the residual ridge.

When implants are placed adjacent to each other, a minimum distance of 3 mm is suggested, especially when crestal bone is expected around the implants, to accommodate for eventual crestal bone loss and maintain interseptal bone levels.

The four conditions that determine the ideal implant size in the posterior maxilla are:

1. The implant dimension should correspond to the natural tooth (2 mm below the CEJ).

2. The implant should be at least 1.5 mm from the adjacent teeth.

3. The implant should be at least 3 mm from an adjacent implant.

4. The implant should be at least 4 mm in diameter.

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