Saturday, February 12, 2011

mandibular major connector (RPD)


Mandibular Major Connector




Relief on the fitting surface :

1 ) Tooth-tissue borne more relief than tooth borne
2 ) Vertical sloping of adjacent alveolar ridge : less relief
3 ) Horizontal sloping of adjacent alveolar ridge : more relief
4 ) Fulcrum line posterior to major connector : less relief
5 ) Fulcrum line anterior to major connector : more relief
6 ) Increased relief  when :
A ) Increased mobility of the abutment teeth
B ) Displaceable of residual ridge
C ) Poor bone quality
D ) Increased labial inclination of lower anterior teeth

Types of Mandibular Major Connector :

 1 ) Lingual Bar
2 ) Lingual Plate
3 ) Double Lingual Bar (Kennedy)
4 ) Labial Bar

Lingual Bar :

1 ) Functional depth of lingual sulcus : >= 8mm
2 ) 3mm from gingival margin
3 ) Half pear shaped cross section :
-superior-inferior  : 4-5 mm
-anterior-posterior : 2 mm
4 ) 3mm + (4-5mm) + 1mm

Lingual Plate :

1 ) Functional depth of sulcus : < 5 mm
2 ) Future loss of natural teeth anticipated
3 ) Lingual tori present
4 ) Posterior teeth have been loss and additional indirect retention is desired.

Double Lingual Bar (kennedy) :

1 ) Indicated primarily when contact with remaining mandibular anterior teeth is indicated, but open embrasures exist, and not indicated when crowding exist.
2 ) Tendency to trap food debris
3 ) Often irritate tongue

Labial Bar : 

1 ) When mandibular teeth severely inclined lingually
2 ) When large lingual tori present and cannot be removed
3 ) 3mm below gingival margin
4 ) Less rigidity because of longer extension

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