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Xbow® Blended Two Phase“The Other Way To Use Class II

Springs”

Duncan W. Higgins DDS MSD FRCD(C)

Conflict of Interest Declaration

I receive royalties from orthodontic labs that are licensed to fabricate the

appliance discussed in this presentation.

US Patent No. 6,168,430 B1

Canadian Patent No. 2,392,021

Xbow® (Crossbow) Class II Corrector

Two Phase Motto

Only place full edgewise appliances on Class I’s…

with adequate maxillary width.

Maxillary Expansion

• Cornerstone of Class II treatment

• Hyrax RME is the backbone of Xbow

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Triple “L” Arch® (Lower Labial Lingual)

Xbow (Crossbow)

• Cross or hybrid appliance

• Lower labial and lingual bow

6+6+12=Blended Two Phase

• 6 months Class II springs on Xbow

• 1 month compensatory maxillary expansion + 5 months retention = 6 months

• During expansion retention we test the Class II correction.

• Replace springs on one or both sides, if necessary

• 12 months phase two.

4 years post RME 2 years post Xbow

(no brackets)

RME

2 monthsInter first bicuspid width

determines archform

RME X 6

RME X 6=“Ideal” Maxillary Width and

Archform for Occlusion, Esthetics, Arch Length, and Palatal Tongue

Position

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Xbow + RME X 6

6 months

IPR

Bite Turbo/Class II

elasticsIndirect Precision

BondingXbow, Secondary

(Compensatory) Maxillary Expansion

Maxillary Incisor and Canine Alignment: RME X 6

Primary Maxillary Expansion

Airway, Nasal Breathing, Palatal Tongue Position

Class II Compensation: Building the Foundation on Maxillary Expansion

Why bother with an extra appliance?Incisor inclination

changes produced by

two compliance-free

Class II correction

protocols for the

treatment of mild to

moderate Class II

malocclusions.

Miller et al.Angle Orthod 2013

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Two Phase Xbow (XB) vs

Single Phase Forsus™ to the Arch Wire (FO)

Conclusions

• The Xbow protocol averaged 6 fewer months of overall treatment and 10 fewer months of fixed edgewise appliances compared to the Forsus protocol. (26.75 months FO group vs 16.68 months in the XB group)

• No differences in incisor inclination between treatment protocols were identified.

• Lower incisors proclined more the longer the treatment.

Xbow’s Target:

Class I first bicuspids bilaterally in phase onePancherz H. AM J ORTHOD. 1982;82:104-113

Lessons from Herbst:“Bite Catching Effect”

• Half cusp over-correction of the upper bicuspid and molar crowns by tipping…

• Followed by Rebound and Periodontal Recovery…

• = Class I Roots

• “Socked In” Steep Cusps = Stability

• Passive retraction of upper incisors by transeptalfiber tension

Lessons from Herbst:“Compensation Compromise”

• Sharing the correction between both arches…

• Instead of pure upper retraction

• Accepting some lower incisor proclination to preserve the upper lip.

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Does orthodontic proclination of lower incisors in children and adolescents cause gingival recession?

S Ruf, K Hansen, H Pancherz

“No interrelation was found between the amount of incisor proclinationand the development of gingival recession.”

“This phenomenon may have been due to the fact that an approximately 80% spontaneous reversal of the incisor proclination

after Herbst treatment occurs.”

July 1998 • Volume 114 • Number 1

Orthodontic therapy and gingival recession: a systematic review

Joss-Vassalli I, Grebenstein C, Topouzelis N, Sculean A, Katsaros C

The amount of recession found in studies with statistically significant differences between proclined

and non-proclined incisors is small and the clinical consequence questionable.

Orthod Craniofac Res 2010;13:127–141

Ceph Studies

• University of Alberta

• Carlos Flores-Mir

• crossboworthodontic.com

Lower Incisor Inclination during Class II Malocclusion Treatment

with the Xbow Appliance followed by Fixed Appliances

Fern Leavens (4th year dental student)

Summer Research Project (2015)

Under the supervision of Dr. Flores-Mir

Unpublished

• 172 consecutively treated patients

• T1-T2 = phase one Xbow, T2-T3 = phase two full edgewise

• The mean lower incisor inclination changed from T1 (99.1o) to T2(102.2o), with a mean difference of 3.1o. The change is statistically significant (p<0.001).

• The mean lower incisor inclination changed from T2 (102.2o) to T3(103.7o), with a mean difference of 1.5o. The change is statistically significant (p=0.01). This may not be clinically significant.

• The mean lower incisor inclination changed from T1 (99.1o) to T3(103.7o), with a mean difference of 4.6o. The change is statistically significant (p<0.001).

Prediction Equations for Final Lower Incisor Inclination

• L1IncDiffT3T1 = - 2.2 + 1.3(OB)

• L1IncDiffT3T

1 = 82(SGo- NMe) - 0.67(SNB)

- 0.25(Ar-Go) + 112

• L1T3 = 50(SGo- NMe) – 0.92 (SNB)

– 0.37(PP-MP) + 0.36(SNA) – 0.26(Ar-Go) + 133

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Simple Linear Regression Model of Change in Lower Incisor Inclination

Based on Initial Overbite

• Prediction equation is L1IncDiffT3T1 = -2.2 + 1.3(OB). Or for every extra mm of OB (greater than ideal overbite of 2mm) there is an increase in lower incisor inclination of 1.3o

Conclusion

• Potential indicators of increased final lower incisor inclination include a deeper initial overbite, vertical growth tendency, a shorter mandibular ramus, a protruded maxilla, or a retruded mandible.

Immediate Skeletal and Dentoalveolar Effects of the

Crown- or Banded Type HerbstAppliance on Class II division 1

MalocclusionA Systematic Review

Barnett et al.Angle Orthod 2008

34

Measurement

de Almeida

2005

Pancherz

1982

SDJ

Pancherz

1982

AJO

Current

Xbow Study

(EMMs)

Md Angulations

NSL/ML (MP-SN) (degrees)0.4 0.2 1.0

L1 Angulation

IMPA (degrees)4 3.8

L1-NB (degrees)5.4

L1 Sagittal

L1-NB (mm)1.0

OLperp – L1 minus OLperp - Pg

(mm)1.8 1.2

L6 Sagittal

OLperp – L6 minus OLperp - Pg

(mm)1.0 0.6

The Nullish Hypothesis

The results are similar for all inter-arch Class II appliances. The differences are probably not

clinically significant.

Ceph Studies

• Flores-Mir C, Barnett G, Higgins DW, Heo G, Major PW. Short-term skeletal and dental effects the Xbow appliance as measured on lateral cephalograms. Am J Ortho DentofacialOrthop. 2009; 136: 822-32. doi:10.1016/j.ajodo.2008.01.021.

• http://www.ajodo.org/article/S0889-5406(09)00874-9/abstract

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Ceph Studies (2)

• Flores-Mir C, Young A, Greiss A, Woynoroski M, Peng J. Lower Incisor inclination changes during Xbow treatment according to vertical facial type. Angle Orthod. 2010; 80: 1075-80. doi: 10.2319/033110-180.1.

• http://www.angle.org/doi/pdf/10.2319/033110-180.1

Ceph Studies (3)

• Aziz T, Nassar U, Flores-Mir C. Prediction of lower incisor proclination during Xbowtreatment based on initial cephalometric variables. Angle Othod 2012; 82: 472-9. doi: 10.2319/072311-465.1.

• http://www.angle.org/doi/pdf/10.2319/072311-465.1

Ceph Studies (4)

• Flores-Mir C, McGrath L, Heo G, Major PW. Efficiency of Molar Distalization with the XBowAppliance Related to Second Molar Eruption Stage. Eur J Orthod 2013; 35: 745-751. doi: 10.10

• http://ejo.oxfordjournals.org/content/35/6/745

Ceph Studies (5)

• Tieu L, Normando D, Toogood R, Flores-Mir C. External Apical Root Resorption generated by Forsus simultaneously with brackets vs. Xbow followed by brackets to correct Class II malocclusions. J World Fed Orthod 2015; 4: 120-3. doi: 10.1016/j.ejwf.2015.07.001.93/ejo/cjs090.

• http://www.jwfo.org/article/S2212-4438(15)00029-6/abstract

Ceph Studies (6)

• Ehsani S, Normando D, Nebbe M, LagravereM, Flores-Mir C. Comparison of dental and skeletal changes in mild to moderate Class II malocclusions treated by either a Twin-Block or a Xbow appliance followed by full fixed orthodontic treatment. Angle Orthod 2015, Nov;85(6):997-1002. doi: 10.2319/092814-696.1

• http://www.angle.org/doi/pdf/10.2319/092814-696.1

Ceph Studies (7)

• Miller R, Tieu L, Flores-Mir C. Incisor inclination changes produced by two compliance-free Class II correction protocols for the treatment of mild to moderate Class II malocclusions. Angle Orthod. 2013; 83: 431-6. doi: 10.2319/062712-528.1.

• http://www.angle.org/doi/pdf/10.2319/062712-528.1