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Diagnostic considerations for Class II treatment with TADs
Shingo Kuroda, DDS, PhD / Tokushima, Japan
Establishment of proper anchorage must be one of the most important keys to achieve
successful results in treating Class II patients. In this decade, emergence of temporary
anchorage devices (TADs) has completely changed the treatment strategy, providing sufficient
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anchorage without patient compliance.
In this lecture, I would like to introduce effective usage
of TADs in Class II treatment and discuss the diagnostic considerations.
Usage of TADs in Class II patients can be classified into two categories. One is the
alternative use of traditional anchorage devices for extraction cases. By utilizing TADs, patients
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could get better results without uncomfortable extraoral appliances. Furthermore, we can
choose the extraction site according to the condition of the tooth, not to the strength of the
anchorage unit.
Another one, use of TADs makes it possible to distalize the maxillary dentition simply, and
expands application of non-extraction treatment. Even with the interradicular screws, the
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maxillary molars could be distalized by 3 mm on average. Interestingly, the mandibular plane
angle was not increased during the distalization. Moreover, our recent study demonstrated newly
bone formation on the maxillary sinus induced by mechanical stress, suggests the maxillary
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distal tooth movement might be a safe procedure in the view of bone physiology. On the other
hand, not all the Class II patients could be treated without extraction. It might be closely related
with the discrepancies between the tooth materials and jaw bones, especially in the mandible.
Not only the sagittal but also the vertical discrepancies could be improved with TADs.
Patients with severe gummy smile have been treated with an orthognathic surgery because
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absolute incisor intrusion was considered difficult. Meanwhile, the recent development of TADs
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makes it considerably possible to intrude the incisors without any undesirable counteractions.
The most evolutionary change in Class II treatment with TADs must be the treatment of anterior
openbite.
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Absolute molar intrusions and the succeeding mandibular counter-clockwise
rotation are quite effective to increase reduced overbite. As a result, the patients could be treated
without surgery even though they have a negative overbite of less than -5 mm.
Conclusively, TADs enhance the quality of Class II treatment with simple mechanics.
References
1.
Kuroda S et al. Root proximity is a major factor for screw failure in orthodontic anchorage.
Am J Orthod Dentofacial Orthop. 2007;131(4 Suppl):S68-73.
2.
Kuroda S et al. Clinical use of miniscrew implants as orthodontic anchorage: success rates
and postoperative discomfort. Am J Orthod Dentofacial Orthop. 2007;131(1):9-15.
3.
Kuroda S et al. Class II malocclusion treated with miniscrew anchorage: comparison with
traditional
orthodontic
mechanics
outcomes.
Am
J
Orthod
Dentofacial
Orthop.
2009;135(3):302-9.
4.
Yamada K, Kuroda S et al. Distal movement of maxillary molars using miniscrew anchorage
in the buccal interradicular region. Angle Orthod. 2009;79(1):78-84.
5.
Kuroda S et al. Mechanical stress induces bone formation in the maxillary sinus in a
short-term mouse model. Clin Oral Investig. 2013;17:131-7.
6.
Kuroda S et al. Severe Class II malocclusion with facial asymmetry treated with intraoral
vertico-sagittal ramus osteotomy and LeFort I osteotomy. Am J Orthod Dentofacial Orthop.
2009;135(6):809-19.
7.
Ishihara Y, Kuroda S et al. Deep overbite correction with intrusion of the mandibular incisors
using miniscrew anchorage. Am J Orthod Dentofacial Orthop, 2013, in press.
8.
Kuroda S et al. Treatment of severe anterior open bite with skeletal anchorage in adults:
comparison with orthognathic surgery outcomes. Am J Orthod Dentofacial Orthop.
2007;132(5):599-605.
9.
Kuroda S et al. Anterior open bite with temporomandibular disorder treated with titanium
screw anchorage: evaluation of morphological and functional improvement. Am J Orthod
Dentofacial Orthop. 2007;131(4):550-60.
10. Kuroda S et al. Severe anterior open-bite case treated using titanium screw anchorage.
Angle Orthod. 2004 ;74(4):558-67.