Immunoglobulin most commmon in Periodontitis

#Which immunoglobulin is most common in patients with periodontal disease?

A. IgA

B. IgD

C. lgG

D. lgE

E. IgM 

The correct answer is C. IgG. 

The presence of IgG in gingival crevicular

fluid is a product of actively secreting plasma cells stimulated by chronic plaque/calculus accumulation. 

The next abundant type is IgA, There is a negligible amount of lgM.

lg A predominates in saliva to agglutinate

bacteria so they are more easily swallowed

and evacuated from the oral cavity.

Lingual holding arch

# A mandibular lingual holding arch with loops mesial to each molar band is used in children for:

A. Correction

B. Regaining space

C. Space maintenance only

D. Correction of distally tilted molars 

 

The correct answer is B. Regaining space.

Normal passive mandibular lingual holding arch is used for space maintenance in mandible. This is  a preventive procedure.

Lingual arch with U loops mesial to each molar band is a modification of mandibular lingual arch. The loops are opened periodically and this can bring about distalization of molars by 1 to 2 mm. This is an interceptive procedure.

Primary source of anaerobic bacteria in diseased periodontal tissue

 # Which of the following is the primary source of anaerobic bacteria in diseased periodontal tissue?

A. Supragingival plaque

B. Blood

C. Subgingival plaque

D. Calculus

The correct answer is C. Subgingival plaque. 

Subgingival plaque is most likely to contain the anaerobic bacteria that cause periodontal disease.

Remember that although calculus is a secondary etiologic factor, the primary etiologic factor of periodontal disease is dental plaque.

All Ceramic Restorations

 # Which of the following is the BEST way to avoid porcelain failure in all-ceramic restorations?

A. Rounded angles of the preparation

B. Minimal occlusal forces

C. Porcelain is 3.5mm thick

D. Porcelain is not more than 0.5mm thick 

The correct answer is A. Rounded angles of the preparation.

All ceramic restorations should include rounded angles in the tooth preparation in order to reduce stress concentration along these areas. Sharp angles within tooth preparations are areas where stress is concentrated, and may cause fracturing.

Porcelain thickness is also an important factor in its fracture toughness. All porcelain crowns should have a minimum thickness of 1mm circumferentially and about 1.5mm along the occlusal/ incisal to

achieve strength (Not including the framework of the restoration).

Proper case selection and occlusal load analysis is also an important factor in preventing failure of an all ceramic restoration.