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 Table of Contents  
CASE REPORT
Year : 2013  |  Volume : 4  |  Issue : 3  |  Page : 353-355  

Removable molar power arm


Unit of Orthodontics, Oral Health Sciences Centre, Post Graduate Institute of Medical Education and Research, Chandigarh, India

Date of Web Publication18-Sep-2013

Correspondence Address:
Ashok Kumar Utreja
Unit of Orthodontics, Oral Health Sciences Centre, Post Graduate Institute of Medical Education and Research, Sector 12, Chandigarh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0976-237X.118341

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   Abstract 

Attachment of force elements from the gingival hook of maxillary molar tubes during the retraction of the anterior teeth is very common in orthodontic practice. As the line of force passes below the center of resistance (CR) of molar, it results its mesial tipping and also anchorage loss. To overcome this problem, the line of force should pass along the CR of molar. This article highlights a method to overcome this problem by attaching a removable power arm to the headgear tube of molar tube during the retraction of the anterior teeth.

Keywords: Biomechanics, molar power arm, orthodontics


How to cite this article:
Verma RK, Jena AK, Singh SP, Utreja AK. Removable molar power arm. Contemp Clin Dent 2013;4:353-5

How to cite this URL:
Verma RK, Jena AK, Singh SP, Utreja AK. Removable molar power arm. Contemp Clin Dent [serial online] 2013 [cited 2019 Jul 19];4:353-5. Available from: http://www.contempclindent.org/text.asp?2013/4/3/353/118341


   Introduction Top


Upright position of the upper molars during retraction of anterior teeth in maximum anchorage cases is very critical in orthodontics. [1] In day to day clinical practice retraction force is usually applied from the power arm attached between maxillary lateral incisor and canine to the gingival hook of maxillary molar tube [2] [Figure 1]. As the force is applied below the center of resistance (CR) of maxillary molars, they tend to tip mesially during the space closure and uprighting of molars is often required during the finishing stage. [3] Also it leads to anchorage loss. Thus to overcome these problems, the force on molars should be applied at their CR, which is at the trifurcation areas. [4],[5] Recently, in a case report Vibhute designed molar stabilizing power arm made up of rectangular stainless steel wire to be engaged in the miniscrew implant head slot and in the auxillary molar tube for optimizing anterior en mass retraction. [6],[7] Here in this clinical tip, we have presented a method to prepare a removable power arm that can be attached to the headgear tube of molar tube during the retraction of anterior teeth.
Figure 1: Use of conventional retraction force from the power arm attached between maxillary lateral incisor and canine to the gingival hook of maxillary molar tube

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   Fabrication Steps Top


  • Take an approximately 3.5 cm of 21 gauge hard stainless steel wire.
  • Then make a "C" shaped hook at its one end and then give 90° bend approximately 6-8 mm below the neck of "C" shaped hook [Figure 2].
  • Then do the stress relieving heat treatment and now the power arm is ready for use.
Figure 2: The PGI removable power arm

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   Clinical Application Top


  • First insert the horizontal arm of the power arm in the round tube of the headgear tube from distal aspect [Figure 3]a and then keeping the vertical arm upright, place a 90° bend to horizontal arm at the mesial end of headgear tube [Figure 3]b so that the mesial and distal arms are parallel to each other and care should be taken that the height of the mesial vertical arm of the power arm is slightly above the gingival hook of the molar tube.
  • Then ligate the mesial vertical arm of the power arm with the gingival hook of the molar tube by ligature wire [Figure 3]c.
  • Now force can be applied from the power arm to the intermaxillary hook for the retraction of anterior teeth [Figure 3]d.
Figure 3

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   Advantages Top


  • Easy to fabricate and use in busy clinical practice
  • Height of power arm can be adjusted depending on the requirement in individual cases. For example distal movement of the molar crown (uprighting) can be done by keeping the height of power arm above the CR of molars during retraction of anterior teeth
  • No special armamentarium is required for its fabrication
  • Can be prepared and stocked.



   Limitation Top


Can cause irritation in the sulcus when either the sulcus depth is less or the height of power arm is very high.


   Conclusion Top


The fabrication and clinical use of this power arm in maxillary first molars during the retraction of anterior teeth is very promising in routine orthodontic practice.

 
   References Top

1.Ammar HH, Ngan P, Crout RJ, Mucino VH, Mukdadi OM. Three-dimensional modeling and finite element analysis in treatment planning for orthodontic tooth movement. Am J Orthod Dentofacial Orthop 2011;139:e59-71.  Back to cited text no. 1
[PUBMED]    
2.Dragiff DA. Technique clinic. Bending the round wire intermaxillary hook. J Clin Orthod 1975;9:578-9.  Back to cited text no. 2
[PUBMED]    
3.Kojima Y, Kawamura J, Fukui H. Finite element analysis of the effect of force directions on tooth movement in extraction space closure with miniscrew sliding mechanics. Am J Orthod Dentofacial Orthop 2012;142:501-8.  Back to cited text no. 3
[PUBMED]    
4.Dermaut LR, Kleutghen JP, De Clerck HJ. Experimental determination of the center of resistance of the upper first molar in a macerated, dry human skull submitted to horizontal headgear traction. Am J Orthod Dentofacial Orthop 1986;90:29-36.  Back to cited text no. 4
[PUBMED]    
5.Viecilli RF, Budiman A, Burstone CJ. Axes of resistance for tooth movement: Does the center of resistance exist in 3-dimensional space? Am J Orthod Dentofacial Orthop 2013;143:163-72.  Back to cited text no. 5
[PUBMED]    
6.Vibhute PJ. Optimizing anterior en masse retraction with miniscrew anchorage. Case Rep Dent 2011;2011:475638.  Back to cited text no. 6
[PUBMED]    
7.Vibhute PJ. Molar-stabilizing power arm and miniscrew anchorage for anterior retraction. J Clin Orthod 2010;44:679-85;688.  Back to cited text no. 7
[PUBMED]    


    Figures

  [Figure 1], [Figure 2], [Figure 3]



 

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  In this article
    Abstract
   Introduction
   Fabrication Steps
   Clinical Application
   Advantages
   Limitation
   Conclusion
    References
    Article Figures

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