August, 2011

A Modified Delta Clasp for Class III Twin block (Clinical Tips)

Corresponding Author

^aRadha Katiyar (1^st Author)

BDS, MDS

Senior  Resident, Faculty  of  Dental  Sciences,  CSM Medical University,  Department of  Orthodontics and  Dentofacial  Orthopedics,  Lucknow,  Uttar Pradesh,  India.

Co-Authors

^bAlka Singh (2^nd Author)

BDS, MDS

Assistant  Professor, Faculty  of  Dental  Sciences,  CSM Medical University,  Department of  Orthodontics and  Dentofacial  Orthopedics,  Lucknow,  Uttar Pradesh,  India.

^cPradeep Tandon (3^rd Author)

BDS, MDS

Professor & Head,  Faculty  of  Dental Sciences, CSM Medical University, Department of Orthodontics and Dentofacial  Orthopedics,  Lucknow,  Uttar Pradesh,  India.

ACKNOWLEDGEMENT: We are thankful to Dr. Kajal Singh for their valuable cooperation.

Address for Correspondence

Dr. Radha Katiyar

Senior  Resident

Department of Orthodontics and Dentofacial Orthopedics

Faculty  of  Dental  Sciences, CSM Medical University

Lucknow(UP)-226003   India.

e mail : dr_rkatiyar@yahoo.co.in

Reverse twin blocks are designed to encourage maxillary development by the action of the reverse occlusal inclined planes cut at a 70 degree angle to drive the upper teeth forward by the force of occlusion. At the same time, it restricts the forward mandibular development.

With a reverse twin block, a reverse pull face mask applies an additional component of orthodontic force to advance the maxilla by elastic traction.

The Delta clasp was designed by the Clark to improve the retention of Twin blocks.^1-2 In this article we describe a modification of the delta clasp that eliminates the need to give any extra wire component for protraction of the maxillae with reverse pull face mask.

The patient shown here had an anterior crossbite with a developing Class III skeletal base relationship. The centre of resistance of the maxillary dental segment presents in between first and second premolars root. Thus, a modified form of delta clasp was designed that engages both the first and second premolars. During wire bending for the delta clasp, an L loop in middle of the bridge region of the clasp is given. The height of this L loop is adjusted to approach the center of resistance of the maxillary segment i.e. in between the roots of both premolars. This wire extension in the form of an L loop is used for maxillary protraction by reverse pull headgear with the help of extra oral elastics.

Fig1: Modified delta clasp

Fig2: Modified delta clasp adapted on both premolars

Fig 3: Modified delta clasp in maxillary plate of twin block

Fig 4: Protraction of maxillary segment with modified delta clasp

Advantages: there is no need for an extra wire component, good retention of the twin block with the delta clasp, can approach the center of resistance by adjusting the height of L loop and there is no tissue impingement.

References:

1:Clark WJ. Twin-block functional therapy. London: Mosby- Wolfe, 1995

2: Clark WJ. The twin block traction technique; European journal of orthodontics, 1982: 4, 129-138.