This patient is a 10 year old female in the late stages of mixed dentition. She presents with upper and lower arch constriction and severe dental crowding. Skeletally, she is a class I with an ANB of 4.5 and WITS of +1.5. She has a normal profile with normal lip competence and the lower incisor to NB ratio to the chin button, NB to Pogonion, is a 2 to 1 ratio which is acceptable with the anticipated growth of pogonion. The mandibular plane angle is 31 degrees which indicates a normal or neutral growth pattern.
The pretreatment study casts show a class II dental occlusion, blocked out teeth upper and lower, as well as gingival recession on the lower left central incisor due to the labial position. Overjet and overbite are normal with the occlusal views showing moderate constriction in both arches.
The treatment plan for this patient is mandibular distalization utilizing the MDA appliance to eliminate the crowding in the lower arch and develop the lower arch to a normal arch form. Once the lower arch is established and developed to the .018 x .025 SS archwire, the upper arch will be distalized to achieve a class I dental relationship. Due to severe crowding in the lower anteriors and the labial position of the left central incisor, it was not possible to get sufficient space through anterior movement and lateral development, thus requiring molar distalization.
Our goal is to progress in the archwire sequence, up to the .018 x .025 SS on the upper and .020 SS on the lower, utilizing the available teeth in the arch forms to prevent round tripping of the teeth, The .018 x .025 SS on the upper arch will serve as sufficient anchorage for the class III elastics to the lower MDA. These are photographs at 12 weeks and we have progressed to the .018 SS upper and lower. Open coil spring is placed with slight activation at the lower left lateral site where a slight space has occurred as a result in lateral arch development.
The MDA appliance has been seated and activated on the lower arch. Due to the constriction and size of the lower arch, the omega on the MDA had to be removed on the left side on the first appliance and .010 x .045 open coil spring placed for activation on that side. Class III elastics are worn from the upper molars to the lower class III hooks of the MDA. The .018 x .025 SS archwire on the upper was used for anchorage but ideally, a transpalatal arch should be placed for anchorage, especially with the limited number of teeth we were able to engage into the archwire sequence on the upper.
The MDA appliance has been activated for nine weeks. There are breaks in the contacts of the lower posterior teeth and significant space distal to the second premolars on both sides. The lower arch has developed laterally through the archwire sequence by crown tipping and uprighting. There has been some forward movement of the upper arch due to the class III elastics and minimum anchorage. This is not a concern because the upper arch will need to be distalized once the lower arch is established.
Every three weeks the patient returns to the office for re-activation of the appliance. The molars will be distalized until we have created enough space in the posterior to accommodate the lower left lateral into the arch form. Once the space is created, we will begin retraction of the posterior teeth to gain space in the anterior.
On the lower arch, power thread is placed directly from the molar to the cuspid on the left and molar to the first bicuspid on the right. The MDA appliance remains seated in the lower arch to prevent the forward movement of the molars and allow distalization of the two lower quadrants. Power thread and power chain will be used to balance out the spacing for utilization. Note the crowding on the upper arch with the blocked out lateral directly lingual to the blocked out cuspid due to the mesial drift of the upper left side.
The lower MDA appliance was removed and the .0175 twisted archwire was seated on the lower arch. Passive ligation to the lower left lateral using a steel ligature wire was indicated to begin moving the lateral into the arch form. Chain elastic is placed on the lower posterior quadrants to consolidate any spacing that is still present.
After 6 weeks using the .0175 twisted archwire on the lower, the left lateral has moved into the archwire enough to get full bracket engagement with the .016 thermal activated nitanium archwire. A rotation wedge is placed on the distal of the lateral to improve the alignment and correct he mesial rotation. This rotation wedge will be left in place throughout treatment to aid in any possible relapse. A thin lip bumper is used to maintain the molar distalization and further develop the arch laterally. Due to the severity of the lingual position of the lower left lateral, it will be necessary to place individual root torque in the tooth once we are in a rectangular archwire.
The lower arch has been established to the .018 x .025 SS archwire. The rotation wedge is maintained on the lower left lateral throughout the archwire sequence to prevent relapse. The lip bumper is also maintained to aid in molar uprighting to the labial, provide anchorage to the lower molars for use of the class II elastics for the upper MDA as well as gaining further arch development. Upper first premolars were bracketed to provide additional support and anchorage for the MDA appliance. She has a full class II dental malocclusion on both sides requiring distalization of 8-10 mm per side.
This photographs were taken after six weeks of distalization, or two activation appointments. Looking at the cusp tips of the premolars, we have moved both sides distally approximately 4 mm and will continue to activate the appliance until the premolars are in the embrasure of a class I relationship and then over distalized up the incline approximately 2 mm. Note the spacing in the premolar area of the upper arch.
With the .018 SS in place on the upper arch, active open coil spring is placed to make room for the upper left lateral incisor. Chain elastic is place buccal and lingual on the left side for maximum retraction and space closure in the posterior. On the lower arch, we have dropped back to the .016 x .022 SS archwire and placing individual root torque into the lower left lateral incisor.
The lateral has moved labially into the arch form and can now be fully engaged into the flexible archwire for alignment. We will progress back through the archwire sequence to the .016 x .022 on the upper and begin placing individual root torque in the upper left lateral.
One of the final steps in the treatment summation sequence is the evaluation of bracket placement for fine tuning and finishing to address the tip or angulation of the teeth. Several brackets were repositioned and a flexible archwire was placed on the upper arch.
These photographs were taken the day bands and brackets were removed. The lower arch was established with distalization and arch development with the archwire sequence. Once the lower arch was established, the upper arch was distalized to establish a class I dental relationship. Both upper and lower arches have developed nicely with the aid of expansion appliances. Total Treatment time was 34 months. Treatment time was extended due to the distalization required to establish the lower arch. The patient declined placement of a fixed lower lingual retainer. Skeletally, the changes were minimal. There is an increase in B-point, reducing the ANB from 5 to 3 which is primarily due to the class II mechanics used for maxillary distalization and auto rotation of the mandible. Lower incisors have moved forward to 7 yielding the same 2 to 1 ratio that was present in the beginning.
These models offer an excellent visual of the amount of arch development achieved through bracket placement and archwire sequence alone, without the aid of any expansion appliances. The distalization process places the teeth in a broader part of the arch form and produces a tremendous amount of space through this arch development. Note the difference in the before and after lateral measurements.
These are the five year post treatment photographs and the dentition has remained relatively stable considering the patient did not wear the hawley retainer and declined placement of the lower lingual retainer. There has been some slight movement of the lower left lateral that was initially blocked out of the arch, but not as much as expected with no retention. I believe this was largely due to the amount of individual root torque placed in the tooth once it was positioned in the arch.