How to properly place a matrix band in a toeffelmire holder in a class 2 prep?
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Answers:
Fold the band to form a loop; notice that when the band is folded, one edge has a smaller circumference than the other; this design accomodates the difference in tooth circumferences at the contact and gingival levels.
Two main rules:
1. Open end of the retainer head is ALWAYS placed toward the gingiva.
2. Smaller circumference of the band is always placed toward the gingiva.
The occlusal edge of the matrix band must be placed in the retainer with the occlusal edge facing the retainer.
In the LRQ & ULQ, the screw side of retainer is faces the buccal surface of the tooth; in the URQ & LLQ, the flat side of the retainer faces the buccal surface of the tooth.
With the rules in mind, place the two ends of the band in the slot of the locking vise. Turn the small knob clockwise, lowering the screw into the vise and thus locking the matrix band within the retainer.
It takes some practice to know when it's right but if you place it in the band - look at the curvature and think of the tooth shape & where you will be placing it - the narrower side will be placed nearest the gingiva. Don't remember my Classes of Preps - sorry. another good tip would be to have your dentist/instructor show you the correct direction - it's easier when it's right in front of you...
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