Modification of twin block functional appliance
- 1. By : Dr . Eithar Sharif supervision Prof dr Maher FOUDA
- 4. The Twin-block (TB) appliance, originally developed by Clarke, is a widely used functional appliance for the management of Class II malocclusion. Its popularity is attributable to its high patient acceptability and its ability to produce rapid treatment changes.
- 6. Consists of separate upper & lower appliances. More comfortable & aesthetic. Pt able to eat & speak without restriction of tongue, lip & mandible movements. Pt able to cooperate to wear appliance to 24hrs.
- 8. Constructed to a protrusive bite. With appliances in mouth, pt not able to occlude in former distal position. Mandible forced to adopt protrusive bite.
- 10. Block ~ 5-6 mm thick between molars (mouth open beyond freeway space) so that pt cannot return to former distal occlusion.
- 12. To standardize the appliance activation vertically, the construction bite was taken with an Exactobite stick (Forestadent, Milton Keynes, United Kingdom), with the incisors in an edge to edge position and separated by 4 mm.
- 13. Construction bite registration for TB appliance taken in edge to edge position with Exactobite stick.
- 15. Baseplate : Upper – up to 6s. Lower – up to ½ cusps of 5s. Expansion screw : Necessary only when compensatory expansion needed to accommodate lower arch as the mandible translates forward.
- 16. Retention : Upper - Adams clasps at upper 6s, 4s. Lower - Adams clasps at lower 4s. Ball clasps at lower anterior teeth
- 17. Occlusal blocks : Upper - From 6s up to mesial of 5s. Lower - From mid cusp of lower 5s to mesial of lower 4s. Occlusal inclined plane– 70.
- 19. This Twin Block design does not have an expansion screw, but labial acrylic on both upper and lower appliances.
- 20. Upper and Lower Twin Block appliances featuring an expansion screw in the upper.
- 21. Upper and lower Crozat Twin Block appliances. The lower appliance is constructed with the crib assemblies on the bicuspid and wire mesh is attached at the end of fabrication to retain the acrylic pad.
- 22. Here we have upper and lower Helical design Twin Blocks. The wire mesh retention is added over the bands after fabrication of the upper Quad and lower Bi Helix.
- 24. 1 st stage –To correct anteroposterior relationship from skeletal Class II to Class I. 2nd stage – Settling of posterior teeth into occlusion from Class II molar relation ship to Class I. Upper bite blocks trimmed to allow eruption of lower posterior teeth. Lower bite blocks trimmed to level occlusal plane.
- 26. In deep bite cases, trim blocks In reduced or open bite cases, do not trim blocks.
- 28. Full time wear for first 6 months , Worn at all times including eating and sleeping. Removed only for brushing of teeth, Not to be worn during sporting activities. Night time wear for next 6-9 months. Finishing may be undertaken with fixed appliances.
- 30. Comfortable ––pt able to eat and speak . Aesthetic ––appliance not obvious . Mandible able to move freely. Compliance ––can be removable or temporarily cemented. Improved facial appearance. Normal speech.
- 31. Easy to manage clinically. Not easily breakable. Allows independent arch development. Improvement of vertical height. Allows for asymmetrical correction. Rapid & efficient correction of skeletal discrepancy & malocclusion.
- 32. Can be undertaken from childhood to early adulthood. May be integrated with fixed appliances. TB of TMJ dysfunction––splint allows displaced disc to be recaptured. TB of sleep apnoea––increases airway space.
- 35. MB appliance, showing maxillary incisor torquing spur with incisor capping.
- 36. Modifications incorporated into this appliance include a facility to incrementally advance the mandible, the use of bite blocks of reduced vertical dimension, and the incorporation of a maxillary incisor torquing spring
- 37. MB appliance. Progressive mandibular advancement achieved by addition of 2-mm Perspex spacers to front of maxillary blocks.
- 39. In this modified appliance the acrylic blocks are attached to bands placed on the maxillary first molars and the mandibular premolars. The blocks are attached by Wilson attachments on the lingual/palatal surface of the bands.
- 40. On the buccal side, a retaining wire (0.7 mm, stainless steel) is fitted into the maxillary molar band headgear tube, and a similar wire is fitted into a tube soldered onto the wings of the edgewise bracket on the mandibular band . The appliance cannot be removed by the patient, and the small gap between the blocks and the occlusal surface is filled with glass ionomer cement. Reactivation of the blocks was carried out when necessary by adding acrylic to the inclined surface of the maxillary block.
- 41. A, Buccal view of maxillary fixed TB component; B, palatal view of maxillary fixed TB component; C, buccal view of mandibular fixed TB appliance; D, lingual view of mandibular fixed TB appliance.
- 43. Clip on fixed functional appliance in place.
- 46. Dr. Gerber has modified his Twin Block design to improve stability and neuromuscular treatment. He has also extended the acrylic and eliminated all sharp edges to create a tighter fitting appliance.
- 47. The appliances can be modified as the case requires and designs may be used in any combination. For example, upper and lower expansion screws may be used for lateral development, an upper sagittal type appliance may be used with a basic lower appliance, and a face bow, or reverse headgear, may be incorporated in the case design.
- 48. For non-compliant patients, Dr. Gerber prescribes his "Banded Block" shown above.
- 50. Torquing springs were used to prevent unwanted retroclination of the upper labial segment. High-pull headgear directed at the center of resistance of the maxilla was used in an attempt to control the vertical position of the maxilla.
- 52. This modification was introduced to reduce the incidence of midline fracture in the lower block, which was found to be the most common removable appliance breakage.
- 54. A. Bite-jumping screw. B. Advancement screws incorporated in maxillary twin blocks.
- 55. Gradual twin block advancement with bite jumping screws in Class II treatment.
- 56. The bite jumping screw was developed to simplify progressive bite advancement with the twin-block appliance. These screws are incorporated longitudinally in the upper bite blocks, with the screw heads at 70° angles to the lower bite Blocks. (The system allows a gradual, 6mm anteroposterior correction in either Class II or Class III cases).
- 57. Gradual advancement of the bite, produces a more orthopedic effect and better patient compliance by reducing tension in the craniomandibular musculature. Also gradual bite advancement would improve patient comfort at rest and during speech, and that it would be more likely to maintain the correct position of the appliance during sleep.
- 58. 9-year-old female patient with severe overbite and Class II malocclusion before treatment.
- 59. Placement of twin block appliance with bite jumping screws.
- 60. Immediate improvement in soft-tissue profile.
- 61. Bite jumping screws built into anterior acrylic plate of maxillary Class III bite blocks.
- 62. Conventional twin blocks are especially difficult to reactivate in Class III cases. Bite jumping screws built into the anterior acrylic plate of the maxillary Class III bite blocks allow easy gradual advancement.
- 64. The only design difference was the incorporation of advancement screws and housings into the maxillary appliance blocks. Further chair side bite advancements were produced by the bilateral addition of 2-mm thick acetal spacers to the maxillary block advancement screws at 6 weekly intervals.
- 65. Standard Twin block appliance. Incremental advancement Twin- block appliance.
- 66. 12-year-old female patient before treatment.
- 67. A. Twin block with initial bite advancement of 3mm. B. After seven months of treatment, with further bite advancements made by adding spacers of 3mm, 3mm, and 2mm bilaterally.
- 68. After seven months of twin-block therapy.
- 70. Expansion and labial segment alignment appliance
- 71. Amodified TB appliance can used to treatment of class II division 2 malocclusions . This avoids the need for an initial period of upper labial segment alignment, which would increase the overall length of treatment. Sagittal correction of the retroclined upper labial segment.
- 72. Both appliances are modifications of the clarck TB. They have a dams clasps on maxillary and mandibular first molars and first premolars, and ball ended clasps on the lower labial segment. The inclined planes are constructed at 70 degrees to the occlusal plane. Advancement, if required is carried out by the addition of small acrylic tablets to the upper block.
- 73. Appliance design with an anterior screw. The additional modifications are detailed as follows: 1. Addition of one anterior screw with torquing spurs both upper central incisors.
- 74. Appliance design with a double cantilever spring. 2. Adouble cantilever spring behind the upper labial segment, followed by bonding of the upper labial segment with pre adjusted Edge Wise fixed appliances.
- 75. Case report : Start records
- 77. Post twin block
- 78. Pre adjusted Edgewise appliances
- 80. Upper Class III twin block Lower Class III twin block
- 81. A modified version of the Clark Class III Twin Block was constructed from heat cured acrylic resin with inclined planes at 70 degrees directing occlusal force downwards and backwards. A midline palatal screw was incorporated for expansion of the upper arch where this was required.
- 82. A lower labial bow and Adams clasps or ball ended clasps on upper and lower first molars and premolars (0.7 mm diameter stainless steel wire) retained the appliance. If premolars were not present then Adams clasps were placed on deciduous molars or C clasps on deciduous canines. Deciduous canines were not routinely removed before treatment.
- 83. before treatment with Class III twin blocks.
- 84. with Class III Twin Blocks in situ.
- 85. After treatment with Class III Twin Blocks.
- 86. Class III Twin Blocks can be used successfully for early treatment of Class IIImalocclusions. The appliance is easily fabricated and well tolerated. Treatment changes shown in this case series were proclination of the upper and retroclination of the lower incisors. There is some decrease in SNB with an increase in anterior vertical dimension.