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Tung Nguyen, Lucia Cevidanes, Marie A. Cornelis, Gavin Heymann, Leonardo K. de Paula, and Hugo De Clerck

American Journal of Orthodontics and Dentofacial Orthopedics December 2011 Vol 140 Issue 6

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Unwanted side effects: o maxillary incisor proclination o clockwise rotation of the mandible

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New treatment methods with skeletal anchorage in the maxillary buttress have been developed to minimize dentoalveolar compensations.

5 Osseointegrated implants as an adjunct to facemask therapy: a case report. Angle Orthod 2000; 70:253-62.

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Osseointegrated implants as an adjunct to facemask therapy: a case report. Angle Orthod 2000; 70:253-62.

De Clerck et al suggested the use of Class III elastics between miniplate skeletal anchorage in both jaws (bone anchored maxillary protraction).

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OBJECTIVETo evaluate in 3 dimensions the growth and treatment effects of the bone anchored maxillary protraction protocol on the maxillary dentition, the midface, and the adjacent soft tissues of consecutively treated patients.

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MATERIALS AND METHODS 25 consecutively treated patients (13 girls, 12 boys) with dentoskeletal Class III malocclusion.

T1 - Initial observation11.9 +- 1.8 years

T2 - End of treatment13.1 +- 1.7 years

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T1 Class III malocclusion in the mixed or permanent dentition Wits appraisal of -1 mm or less. Anterior crossbite or incisor end-to-end relationship. Class III molar relationship. Prepubertal stage of skeletal maturity according to the cervical vertebral maturation method (CS1-CS3).

o T1 to T2 interval - 1.2 +- 1.0 years

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Each patient had miniplates placed on the left and right infrazygomatic crests of the maxillary buttress and between the mandibular left and right lateral incisors and canine.

Small mucoperiosteal aps were elevated, and the modied miniplates were secured to the bone.

The extensions of the plates perforated the attached gingiva near the mucogingival junction. 11

Three weeks after surgery, the miniplates were loaded. Class III elastics applied an initial force of 100 g on each side, increased to 150 g after 1 month of traction and to 250 g after 3 months. In 14 patients, after 2 to 3 months of intermaxillary traction, a removable bite plate was inserted in the maxillary arch to eliminate occlusal interference.

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Cone-beam computed tomography (CBCT) scans were taken at T1 and T2 by using an iCat machine. Virtual 3D surface models were constructed from the CBCT images. The T1 and T2 images were registered by using the anterior cranial fossa as a reference, specifically the endocranial surfaces of the cribiform plate region of the ethmoid bone and the frontal bone. o These regions were chosen because of their early completion of growth.

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The isoline tool was used to quantitatively measure the greatest displacements between points in the 3D surface models for: o o o o o the maxillary incisors, the maxilla, the right and left zygomas, the upper lip, the soft-tissue nose.

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For the maxillary incisor, the maximum surface distance was measured at the incisors most labial surface. The maxillary region was dened as the anterior surface of the maxilla between the canines. The right and left zygomas were dened as the surfaces adjacent and superior to the bone anchors. The soft-tissue nose region was dened as the tip of the nose. The upper lip was dened as the area below the nose between the lip commissures. Positive values indicated anterior displacement, and negative values posterior displacement.

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RESULTS

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Three-dimensional skeletal color maps of superimpositions of T2 over T1 registered at the anterior cranial base with a scale of -5 to +5 mm

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Lateral views of the skeletal semitransparency superimpositions

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Frontal views of 3D soft-tissue color maps of superimpositions

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Lateral views of the soft-tissue semitransparency superimpositions

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DISCUSSION Two dimensional studies of maxillary protraction have limitations, since the landmarks evaluated are often midline structures or 2D projections of 3D structures. Furthermore, bilateral structures cannot be evaluated individually and are susceptible to measurement errors if the patients head is slightly rotated during lm capture.

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Three-dimensional color maps and semitransparency superimpositions showed no signicant proclination of the maxillary incisors with bone anchored maxillary protraction.

There was a statistically signicant correlation between the magnitude of displacement of the left and right zygomas, the maxilla, and the maxillary incisors, suggesting that the midface was displaced anteriorly as a unit.

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The 3D color maps show that bone-anchored maxillary protraction patients had uniform anterior displacements of the maxilla and the zygoma. 2D cephalometric study showed minimal counterclockwise rotation of the maxilla with bone-anchored maxillary protraction treatment.

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Another nding was the opening of the circummaxillary sutures that was evident in a number of subjects. The high potential of adaptation in the transverse palatine, zygomaticotemporal, and zygomaticofrontal sutures might explain why the maxilla, the zygomas, and the maxillary incisors moved forward as one unit.

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Three-dimensional analysis of maxillary protraction with intermaxillary elastics to miniplates Heymann et al (AJODO 2010)

6 patients with Class III occlusion and maxillary deficiency. CBCT scans taken before and after treatment.

All 6 patients showed improvements in the skeletal relationship, primarily through maxillary advancement with little effect on the dentoalveolar units or change in mandibular position.

Three-dimensional analysis of maxillary protraction with intermaxillary elastics to miniplates Am J Orthod Dentofacial Orthop 2010;137:274-84

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Comparison of two protocols for maxillary protraction: bone anchors versus face mask with rapid maxillary expansion Baccetti et al (AO 2010) Objective To test the hypothesis that there is no difference in the active treatment effects for maxillary advancement induced by boneanchored maxillary protraction (BAMP) and the active treatment effects for face mask in association with rapid maxillary expansion (RME/FM). Materials and Methods BAMP 21 subjects RME/FM 34 subjects T1 and T2Comparison of two protocols for maxillary protraction: bone anchors versus face mask with rapid maxillary expansion Angle Orthod. 2010;80:799806 26

Results and Conclusion

The BAMP protocol produced significantly larger maxillary advancement than the RME/FM therapy (with a difference of 2 mm to 3 mm). Additional favorable outcomes of BAMP treatment were the lack of clockwise rotation of the mandible as well as a lack of retroclination of the lower incisors. Bone-anchored maxillary protraction produced 2.3 to 3 mm more of maxillary protraction compared with facemask or rapid maxillary expansion treatment.

Comparison of two protocols for maxillary protraction: bone anchors versus face mask with rapid maxillary expansion Angle Orthod. 2010;80:799806

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CONCLUSION The 3D evaluation of the therapeutic effects of the bone-anchored maxillary protraction protocol in Class III growing patients showed signicant maxillary and zygomatic protraction with hardly any skeletal rotational changes or dental compensation of the maxillary incisors. The soft-tissue changes were also signicant and comparable, although evident only at the level of the upper lip.

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CRITICAL APPRAISAL Placing of the mini plates can cause trauma to the patient. Not cost effective. Comparisons have been done with 2D studies. Follow up after the treatment and retention period to evaluate the stability of the treatment.

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