Maxillary Transverse/Anterio-Posterior Expansion: MAX TAP

The Xbow System is based on treating to an ideal maxillary arch form

and width. Combining anterior alignment with

Rapid Maxillary Expansion is more effective than

archwire expansion by itself.

Class II

Class III

All images are the property of Dr. Duncan W. Higgins

and cannot be copied or reproduced without the consent of Dr. Higgins.


Xbow Max TAP appliance with 12 mm RME, 100 gram shorty open coil nickel titanium springs to open space for canines,

occlusal rests for second molars. Mini tubes are welded to the first bicuspid bands in such a way as to

control the movement of the canine and incisor occlusal plane.

After 6 months Max TAP


1. 2X6 RME 2. Xbow 2 months

14 months full braces

Upper lip preservation with a convex profile and obtuse naso-labial angle



Max TAP Xbow with mesial hookup and upper incisor segment

Xbow Max TAP appliance with mesial hookup and archwire segmented distal to canines before Class II spring attachment

Xbow Max TAP after Class II springs removed after over-correction of Class II, shows spring side effect of buccal segment

occlusal plane tipping down in front. If archwire was not segmented the anterior teeth would have been extruded

and tipped lingually into a crossbite, increasing the risk of incisor root resorption.




Max TAP Cases treated by Dr. Higgins


After upper incisor alignment, day of Xbow insertion

After 3 months of Xbow followed by compensatory maxillary expansion, now will retain expansion and test Class II correction

for 5 months before removing appliances.

Ready for phase 2 braces

8 months braces



This high angle patient presented with a half cusp Class II bicuspid relationship and a bicuspid openbite on the right side.


.The Xbow RME was cemented as well as an upper 2X6 due to the lingually blocked lateral incisors.

Once the anteriors were aligned the Triple "L" Arch and springs were placed.

The springs were on for 3 months before compensatory maxillary expansion was started.

The expansion was retained for 5 months before the appliance was removed and an upper Essix retainer was delivered.

10 months braces


This next patient is an example of upper anterior crowding where the molars are Class I but the bicuspids are

a half cusp Class II and the upper canines are blocked out and a full cusp Class II.

This required an upper 2X6 appliance to align the anteriors before the placement of the Triple "L" Arch and springs.


After upper alignment and Xbow correction to Class I bicuspid. Leave springs on to over-correct.

Day of spring removal after over-correction. Springs were on for 4 months.

RME and 2X6 with upper second molar mini tubes on bicuspid bands___.016X.025 SS anterior segment

(Use active retraction of upper incisors with a continuous archwire as little as possible to avoid root resorption.)

Day of appliance removal and placement of upper Essix retainer, bicuspid Class I, ready for indirect bonding of full braces.

7 months braces



Upper 2X6, 4 months Xbow, ready for maxillary expansion

11 months after spring removal, full braces have not been used


Class III malocclusion

Max TAP is used with Class III malocclusions when maxillary expansion and/or upper incisor proclination is indicated.

A reverse pull headgear (protraction face mask) can be added by attaching elastics to the first bicuspid hooks

or the long ends of the archwire distal to the bicuspid tubes.



End of phase one

1. RME to open space for upper lateral incisors.

2. Upper 2X4 and bonded posterior bite blocks to rotate mandible down and back and then procline upper inciosrs.

This is standard treatment for a Class III to avoid jaw surgery. Note improvement in upper lip fullness.

Class II compensation compared to Class III compensation

In Dr. Casko's untreated ideal occlusion study where the ANB angle was -3 degrees, the lower incisor was compensated back

to 83 degrees while the upper incisor was compensated out to 120 degrees. In order to prevent Class III surgery orthodontists

will procline upper incisors out to 120 degrees without a second thought, which is 18 degrees past the norm.

The same orthodontists may criticize a lower incisor proclined to 106 degrees in a Class II patient, which is only 10 degrees past the norm.

Same patient as above, flipped lower to upper. Why should a Class II be treated differently than a Class III?



proclining upper incisors to avoid Cl III surgery







maxillary expansion only to open space for the upper lateral incisors, mandible rotated down and back, correcting the anterior crossbite.


maxillary expansion and protraction headgear for 4 months followed by 2 months settling

9 months braces



6 months maxillary expansion and protraction facemask, photos taken one month after appliance removal,

note mandibular asymmetry, Class II right, Class III left

RME and protraction facemask