A Modern Approach to Phase 1 Orthodontic Treatment by Dr. David R. Boschken

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A Modern Approach to Phase 1 Orthodontic Treatment   

A case report on simultaneous clear palatal expansion and aligner therapy

by Dr. David R. Boschken

Diagnosis:
  • Early mixed dentition with Class II division 2 malocclusion (Figs. 1–3)
  • Mesially rotated upper first molars
  • Moderate maxillary and mandibular arch constriction
  • Mild maxillary and moderate mandibular crowding (3 mm in the upper, 5 mm in the lower)
  • Overbite: 60% (moderate deep bite)
  • Overjet: 1.5 mm
  • Lower midline slightly to the right of the upper
  • No periodontal issues noted
  • Mild plaque noted on the upper anterior teeth
Treatment goals for Phase 1 orthodontic treatment:
  • Palatal expansion of the maxilla to increase the upper transverse dimension skeletally
  • Aligned upper and lower anterior teeth
  • De-rotated permanent upper first molars
  • Coordinated arches, a leveled occlusal plane, ideal overbite and overjet, and centered midlines
  • Create equal space around the upper and lower primary canines to help the permanent canines avoid interference from the adjacent teeth during eruption
Phase 1 treatment plan:
  • Widen the maxillary arch by 6 mm using clear, removable palatal expanders (Invisalign Palatal Expanders) at 0.25 mm of expansion per active appliance (Figs. 4a–b)
  • Start clear aligner treatment (Invisalign First) in the lower arch at the same time as the upper expansion for arch coordination
  • Re-scan the patient’s teeth and bite after the upper expansion has been stabilized for three months to add clear aligners to the upper arch. Re-scan again as needed for additional aligners to complete Phase 1 treatment
  • Maintain the treatment results with removable retainers and re-evaluate for Phase 2 treatment after the permanent canines and premolars have erupted
A Modern Approach to Phase 1 Orthodontic Treatment
Fig. 1: Initial smile photo.
A Modern Approach to Phase 1 Orthodontic Treatment
Fig. 2: Initial panoramic radiograph.
A Modern Approach to Phase 1 Orthodontic Treatment
Fig. 3a: Initial cephalometric radiograph.
A Modern Approach to Phase 1 Orthodontic Treatment
Fig. 3b: Initial cephalometric radiograph.
Palatal expander sequence and results
Maxillary skeletal expansion was achieved using 24 expanders (the goal was approximately 6 mm increase in width). The intermolar width between the initial scan and the post-expansion scan increased by 5.3 mm as measured from central fossa to central fossa of the upper 6’s, using a point-to-point measurement software tool (OrthoCAD). The midline diastema post-expansion was 3 mm wide. At this point, the lower arch was in aligner #6 of 23 (Fig. 5). Spontaneous anterior alignment was noted during the three-month stabilization period, as is often observed when more space for the teeth becomes available after maxillary skeletal expansion1 (Fig. 6). The total time for the palatal expansion phase was 4.2 months.

After upper expansion plus three months of expansion stabilization (and 23 initial lower aligners to coordinate the arches during expansion), new scans were taken to include the upper arch in aligner treatment. A series of 27 additional U/L aligners was worn, with the aligners changed every five days. A new scan was then taken for detailing (Fig. 7).

A second round of upper aligners (third round in the lower arch) was used to improve the root tip of the upper central incisors and adjust the leeway spaces (16 U/L aligners). Vertical attachments were used on the upper central incisors for tip control (Fig. 8).

The total Phase 1 treatment time from initial appliance delivery to retention was 10.2 months (Figs. 9–11). Clear removable retainers are being worn at night until they no longer fit because of permanent tooth eruption. We will evaluate the patient for Phase 2 treatment after the permanent bicuspids and canines have erupted.
A Modern Approach to Phase 1 Orthodontic Treatment
Fig. 4a: Early in expansion treatment.
A Modern Approach to Phase 1 Orthodontic Treatment
Fig. 4b: After expansion stabilization.
A Modern Approach to Phase 1 Orthodontic Treatment
Fig. 5: Post-expansion scan.
A Modern Approach to Phase 1 Orthodontic Treatment
Fig. 6: Scan results after 3 months of upper expansion stabilization and 23 lower aligners.
A Modern Approach to Phase 1 Orthodontic Treatment
Fig. 7: Scan results after 27 U/L aligners.
A Modern Approach to Phase 1 Orthodontic Treatment
Fig. 8: Scan of final Phase 1 treatment results after 16 additional U/L aligners (total treatment time: 10.2 months). The attachments in the scan were virtually removed by the lab technician before the patient’s clear retainers were made.
Discussion
The digital orthodontic tools and technologies we have implemented in our practice make our patient onboarding and treatment processes flow seamlessly from beginning to end. The goal with our young patients is to reassure them (and their parents) that any orthodontic treatment they receive from us will be delivered with utmost comfort, convenience, and care in mind.

We begin the new patient process by taking completely digital records for diagnosis and treatment planning. Our intraoral scanner (iTero Lumina) automatically generates photorealistic 2D intraoral photos (right buccal, anterior, left buccal, upper occlusal, and lower occlusal). The scanning process is also more comfortable than traditional impressions, which is especially useful for patients with smaller mouths or sensitive gag reflexes. A copy of these records can be sent to our lab for appliance fabrication once the patient is ready to move forward with treatment, and no second office visit is required to start, even for patients who need palatal expansion as part of their Phase 1 treatment. The ability to quickly prepare the patient’s records for the lab is particularly important with younger patients, because the longer the delay in getting started after the records are taken, the higher the risk of poor initial appliance fit. A quick and comfortable records appointment also helps us build patient confidence right away and gives us more time to discuss effective solutions to address the patient’s concerns.

Appliance selection considerations
As a rule of thumb for correcting transverse discrepancies, if a young patient with a narrow maxilla needs more than 5 mm of expansion, we like to use clear, removable palatal expanders to widen the jaw skeletally. For less than 5 mm of expansion, we will typically use clear aligners for dentoalveolar expansion.

Like clear aligners, the palatal expanders are removable, so the patient’s teeth are easy to brush and floss. The expanders clip onto bonded composite attachments similar to attachments for clear aligners. The expander attachments are used for appliance retentiveness and to minimize buccal crown tipping.

As a general guideline, our target for palatal expansion is to achieve a minimum of 50 mm width between the upper first molars as measured from central fossa to central fossa. This width ensures ample leeway space for the unerupted canines and establishes a broad arch form. The patient in this case report was treated to a final molar width of 49 mm (for a total gain of 5.3 mm), which was 1 mm short of our goal of 50 mm, but adequate leeway space was achieved, so no additional expansion was prescribed.

Patients are instructed to wear their expanders 24 hours a day, including while eating. If eating is not possible with the device in place, they should reinsert it immediately after eating. We recommend switching out the expanders every day for the first eight devices; from device #9 onward, they are changed every two to three days. The goal of this protocol is to rapidly separate the palatal suture by 2 mm with the first eight devices and then slow down the cadence once the suture is opened, so that the patient has a little more time to ensure a good fit of each device before moving on to the next one. We have noticed a significant reduction in expander fit issues with this protocol, compared to when the expanders were being switched daily. More research is needed to quantify the effects of using this protocol, but allowing an extra one to two days per device after the first eight are worn seems to let each appliance settle around the teeth and attachments better.

No issues related to pain, speech, wear compliance, appliance maintenance, or brushing and flossing were reported by the patient. In general, the parents of our palatal expansion patients have been very pleased at how easy the process is and how little they are required to do. No longer do parents need to turn an expansion screw or help their kids brush around cemented bands. Many parents who had maxillary expansion themselves when they were younger also remember the discomfort they felt after elastic separators were placed—with this protocol, no elastic separators are needed. Having the expansion built into the appliances means parents have one less thing to worry about or to add to their to-do lists.

Appointment scheduling for Phase 1 patients
Overall, our office workflow for palatal expansion is much more efficient than our previous protocol with analog expansion devices.

For Phase 1 aligner patients, we no longer schedule follow-up visits using a fixed interval of every 10–12 weeks. Instead, we schedule in-office visits based on when their entire batch of aligners will be completed. Patients know that they will visit us after they finish their current aligner series, and that we will re-scan their teeth and bite at the next visit if additional appliances are needed. This arrangement works better for our patients’ busy schedules.

Since brushing and flossing is very convenient with clear aligners, appointments can be spaced farther apart without worrying about food and plaque getting trapped around their orthodontic appliances for prolonged periods. With no poking wires or loose brackets to fix, unscheduled emergency visits are also rare.

Instead of removing all existing attachments during the re-scan visit, we ask the lab to virtually remove from the patient’s intraoral scan any attachments that need to be changed, and only these attachments are removed at the next aligner delivery appointment. Any other attachments will remain on the patient’s teeth until their Phase 1 treatment is completed.

Like our aligner visits, progress visits for palatal expansion patients have also been quick. Our current scheduling protocol is to see patients back in the office when they are halfway through their expanders, and then again after the last expander, to determine if additional expansion is needed. 
A Modern Approach to Phase 1 Orthodontic Treatment
Fig. 9: Post-treatment scan after all the aligner attachments were removed.
A Modern Approach to Phase 1 Orthodontic Treatment
Fig. 10: Progress panoramic radiograph to assess the positions of the upper central incisor roots and the erupting permanent canines.
A Modern Approach to Phase 1 Orthodontic Treatment
Fig. 11: Smile photo at the completion of Phase 1 treatment.

References

1. Applied Sciences 2021;11(12):5748. https://doi.org/10.3390/app11125748

Author Bio
Dr. David R. Boschken Dr. David R. Boschken has been providing clear aligner treatment to patients in the San Francisco Bay Area since 2000 and has successfully treated more than 7,000 patients. Boschken is the longest-tenured Invisalign faculty member and lecturer, teaching clinicians worldwide for more than 26 years. After graduating from the University of California, Berkeley, with a double major in biochemistry and anthropology, he received his dental degree and training in orthodontics from the University of Pennsylvania’s School of Dental Medicine. Following his graduation, Boschken completed a hospital residency at Guy’s and St. Thomas’ Hospital in England. In addition to owning two private practices in Los Altos and San Jose, California, Boschken enjoys boating and skiing in Tahoe with his family during his free time.


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