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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.

Xbow® (Crossbow) Class II CorrectorUS Patent No. 6,168,430 B1

Canadian Patent No. 2,392,021

Maxillary Expansion

• Cornerstone of Class II treatment

• Hyrax RME is the backbone of Xbow

Triple “L” Arch® (Lower Labial Lingual)

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Xbow (Crossbow)

• Cross or hybrid appliance

• Lower labial and lingual bow

Two Phase Motto

Only place full edgewise appliances on Class I’s…

with adequate maxillary width.

IPR

Bite Turbo/Class II

elasticsIndirect Precision

BondingXbow, Secondary

(Compensatory) Maxillary Expansion

Maxillary Incisor and Canine Alignment: RME X 6

Primary Maxillary Expansion

Nasal Breathing, Palatal Tongue Posture

Xbow Two Phase Treatment

Eruption Based Treatment Sequencing U7-12-13 yr

L7-11-13 yr

L4-10-12 yr

U3-11-12 yrU4-10-11 yr

Foundation = Nasal Breathing and Adequate Maxillary Width

Xbow’s Target:

Class I first bicuspid bilaterally in phase one

Pancherz H. AM J ORTHOD. 1982;82:104-113

???

• Does it make a clinically significant difference which inter-arch Class II appliance I use?

• Why not use an appliance with more asymmetric control?

• Do I really need stainless steel crowns?

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6+6+12=Blended Two Phase

• 4-6 months Class II springs on Xbow

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

• During expansion retention we test the Class II correction.

• Replace springs on one or both sides, if necessary

• R and R: Rebound and Periodontal Recovery

• Allow the Class II spring side effects to settle.

• 12 months phase two.

2 months exp/align

RME X 6

Xbow + RME X 6

6 months

???

• Why bother with an extra appliance when I can do everything with a full edgewise appliance?

• Does two phase treatment really shorten the time in a full edgewise appliance?

• How does Xbow two phase treatment compare to Forsus™ to the arch wire single phase treatment?

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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

Conclusions

• The Xbow two phase protocol averaged 6 fewer months of overall treatment and 10 fewer months of fixed edgewise appliances compared to the Forsus to the archwire single phase protocol. (26.75 months for the Forsusto the archwire group vs 16.68 months for the Xbow group)

Conclusions (2)

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

• Lower incisors proclined more the longer the treatment.

???

• How can single phase treatment take longer than two phase?

• Is there a better time to deal with the side effects of the Class II springs such as openbite?

RME X 6/Xbow

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Isolate the anterior teeth from the side effects of the Class II springs. Avoid anterior canting when a spring is used on one side only.

Allow settling of the side effects before phase two.

Studies

• University of Alberta

• Carlos Flores-Mir

• The following web page has links to the studies.

• http://www.crossboworthodontic.com/xbow.htm#research

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.

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.

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.

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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

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.

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

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.

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).

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Prediction Equation for 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 the ideal overbite of 2mm) there is an increase in lower incisor inclination of 1.3o

???

• Is there any rationale for proclining lower incisors 4.6 degrees?

• Can the periodontium tolerate it?

Dental and Skeletal Variation Within the Range of Normal

JOHN S. CASKO, WALTER B. SHEPHERD

The Angle Orthodontist: 1984, Vol. 54, No. 1, pp. 5–17.

Untreated Class II and Class III Skeletal Samplewith Ideal Occlusion

(Naturally Compensated)

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

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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

44

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 analysis of the effect of treatment with functional appliances vs an untreated control group showed that skeletal changes were statistically significant, but unlikely to be clinically significant. (Am J Orthod Dentofacial Orthop 2011;139:24-36)

My Nullish Hypothesis

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

clinically significant.