Fig. 7.24 Triangle formed from the lower part of Fastlight's tetragon.
Viewing the dental complex in this manner provides excellent information on incisor torque, and demonstrates that different normals need to be used, depending on the underlying skeletal pattern (Fig. 7.25).
Anterior torque compensation is typically necessary in high-angle Class I cases, and in cases with Class II or Class III skeletal bases, unless it is planned to use surgery to correct the skeletal pattern as part of treatment.
Part of the skill in Class II treatment planning lies in balancing the wish (o avoid surgery against the unfavorable effect on facial profile which can result from incisor torque compensation. How much compensation of torque can be accepted before it has to become a surgical case?
Incisor torque is controlled by the action of the rectangular .019/.025 wire in the 022/.028 bracket slots. The MBT™ bracket system has been designed to reduce the amount of wire bending needed. Despite this advance in bracket design, where necessary the orthodontist needs to accept the possible need to introduce bends into the steel rectangular wire, to add or reduce incisor torque, according to the requirements of individual cases (Case DO, p. 210).
Fig. 7.25 Viewing the dental complex as tetragons divided into two triangles provides excellent information on incisor torque. Different normals or goals will be required, depending on skeletal pattern. The maxillary and mandibular triangles show typical anterior torque in various clinical situations. These will be referred to later (p. 179) in the discussion on lower incisor torque. It is important to note that these torque recommendations are for the long axes of the incisor teeth, as measured cephalometrically. This is in contrast to the torque values for the bracket designs, quoted elsewhere in this book (p. 33), which are relative to the labial surfaces of the clinical crowns.
Class I high angle
Figs 7.26 and 7.27 Upper incisors may be intruded, relative to lip line, if the patient is prepared to wear a 'J' hook type of headgear. Careful contouring of the metal 'J' hooks is required so that they follow the contour of the cheeks.
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