Passive Ligation, Active Results by Dr. Todd Bovenizer

More Options
Dentaltown Magazine

These case studies illustrate treatments where passive self-ligating brackets made the best choice

by Dr. Todd Bovenizer

Life is all about choices. We have the opportunity to choose where we live, whom we become friends with, where we’ll go to school, what we’ll study—the list goes on and on. These choices have consequences, both positive and negative, for us and those around us. While it’s impossible to avoid the risks often associated with making a choice, our decisions are typically made with great intention, consideration and thought. We weigh the pros and cons and come to a solution that we think will deliver the best end result.

Business decisions—and, in our case, treatment choices—are no different. When reviewing a patient case, we deliberately assess the problem, vet solutions, discuss pros and cons with the patient and ultimately come to a decision that will give both parties (doctor and patient) a desired final smile and guided occlusal result.

In orthodontics, we know that there is by no means a one-size-fits-all option. Some patients may be better suited for clear aligners, and some will benefit from fixed appliances. In my hands, a passive self-ligating system with high-tech light-force archwires and minimally invasive treatment protocols has proven to deliver consistent results. One thing in common with just about all cases is the patient’s desire for aesthetics, convenience, a minimal number of appointments, comfort and speed of treatment. I have leveraged a variety of techniques and mechanics throughout my professional career, but the following cases and analysis support and portray passive self-ligating (PSL) bracket systems, which have consistently delivered beautiful finishes across a variety of cases.

Passive self-ligation
Self-ligating brackets have become widely used in the past decade. Such brackets have a proven track record for delivering exceptional patient results—with the utmost control and convenience—and, in my experience, in less time and with more comfort than traditional braces. Of note, the Damon System is a treatment system I’ve used for some time, because it offers a combination of PSL brackets, light-force archwire sequencing and minimally invasive treatment protocols. Damon Q2 is the newest addition to the system, and features twice the rotation control.

I have chosen the following two cases to demonstrate why PSL was chosen, and the added value it provided throughout the treatment process. These cases have very similar clinical considerations and may have the tendency to result in bimaxillary protrusion. I find these types of cases to be very challenging, and at the same time rewarding. I have found that with PSL, especially in the finishing stages of treatment with SS wires, nice posterior expansion can be utilized while uprighting the anterior segments. This is always challenging for me and in the past may have left me finishing these cases with bimaxillary protrusion. I feel these cases can prove to be very difficult and if careful attention is not given, potentially a less-ideal result could be obtained.


Office Highlights

Case 1

Diagnosis: Class II skeletal and dental with obtuse nasolabial angle and thin maxillary lip. End on Class II with severe maxillary crowding with blocked-out canines. Moderate mandibular crowding including a steep Curve of Spee and thin mandibular tissue on #24/25.

Treatment planning: For this case, I followed fundamentals for facial-driven treatment planning. With the facial considerations outlined above, a non-extraction treatment plan was desired, although the family was warned that extractions might be needed. Upon assessing the case further, it was determined that it had a strong tendency to develop into bimaxillary protrusion. As such, incredibly careful mechanics were prescribed and employed to avoid this. In treating to the maxillary incisor position, it’s imperative to visualize a proper profile before beginning treatment. Further, with proper differential torque selection, early light elastics, bite turbos and meticulous enamel reshaping, I’ve found that reasonable outcomes can be predicted. By developing the transverse early on in copper nickel titanium (CuNiTi) and later in stainless steel (SS) wires, uprighting of incisors can be visualized.

Torque selection and case setup: Low torque on U/L 2–2, standard torque on maxillary cuspids and high torque on mandibular cuspids (Fig. 1).

Appointments

  1. I bonded up this patient U/L 6–6. I chose to engage all teeth on 0.014 CuNiTi wires except for the maxillary 3s and the mandibular left 2s. I used very light open-coil springs for these teeth (imperative for 1/2 bracket activation to not use too much force). I chose to disarticulate the patient’s occlusion by placing bite turbos on the mandibular first molars. I started this patient on shorty Quail elastics from Ormco: 3/16 inch, 2oz.
  2. The second appointment was at 10?weeks (Fig. 2). I placed U/L 0.018 CuNiTi and engaged the lower left 2. I placed brand-new titanium coils on the maxillary cuspids. The patient was instructed to continue the shorty Class II Quails.
  3. At 18?weeks, I engaged the maxillary cuspids with 0.013 CuNiTi wire and again the patient was instructed to continue shorty Class II Quails.
  4. Six months into treatment, I placed maxillary and mandibular 0.018 CuNiTi wires and again placed her on shorty Class?II Quails. As you can see, during the first six months, my goal was to resolve all crowding with light, round CuNiTi wires, to disarticulate the bite and to get some of the Class II corrected.
  5. At eight months into treatment I placed rectangular wires for the first time to begin gaining a couple in the bracket slot. I placed maxillary and mandibular 14x25 CuNiTi wires and also moved her elastics to longer Class II Parrots from Ormco (Fig. 3). I had been really patient to this point, developing the transverse and using very light forces. Having said this, I noted protrusion of the incisors, which I anticipated. At this point into cases like this, the orthodontist must be in a read-and-react mode. One must create more overjet to correct remaining Class II and also tip the teeth lingually. The tissue on the mandibular anterior must also be at the forefront in our thought process while we’re working through this treatment.
  6. Most of the time, I follow up with 18x25 CuNiTi wire on the maxillary arch and a 16x25 CuNiTi wire on the mandibular arch. I rarely use any wire larger than this on the mandibular arch, which fascinates me because there is a tremendous amount of play in this wire, which further justifies passive self-ligation for me. I kept her on 2oz. Class II Parrots and scheduled her for progress pan and repositioning in eight weeks.
  7. The seventh appointment was at 12 months. As I mentioned in the 14x25CuNiti appointment, one must be ready to read and react. At this appointment I chose to place 20 degrees of lingual crown torque in each arch for a six- to eight-week time period. These wires cannot be unattended for longer appointments and my goal was to obtain some retraction of the incisors due to some more protrusion.
  8. At 14 months, I completed repositioning in the maxillary and mandibular arches and moved back down in wire size to 14x25 CuNiTi wires and again placed her on longer Class II Parrots for more Class II correction. I would like to note that we have not used more than a 2oz. elastic.
  9. At 16 months, I moved into stainless steel archwires, U19x25 SS and L16x25 SS (Fig. 4). I purposely expanded these wires to gain more transverse expansion in the posterior. I used power chain under the wire to help retract incisors after interproximal enamel reduction (IPR) was done on the maxillary incisors. I am really comfortable with the case progression at this point.
  10. At 18 months I reconfigured the SS wires on my archwire grid and expanded them. I also did some IPR on the mandibular arch. I used a sling power chain to aid in more uprighting of the incisors. I had her on ¼-inch 4oz. elastics at nighttime only.
  11. At 23 months a retie was done with reconfiguration of wires and a sling power chain (Fig. 5).
  12. 24 months (Fig. 6).
Dentaltown Magazine
Dentaltown Magazine

As you can see, with predictable, simple and consistent mechanics, one can work through a challenging case with protrusion as an often side effect. I love seeing the upright maxillary incisors and detailed occlusion, and I love that with PSL I can do much of my Class II mechanics and it allows me to focus on finishing.


Office Highlights

Case 2

This case has similar characteristics to the first case, except that the maxillary canines are in the arch length, already presenting as bimaxillary protrusion. In the previous case, it would have been very difficult to produce results where the incisors finished upright without using careful mechanics.

Diagnosis: Skeletal and dental Class II with mandibular retrognathia and lip incompetence. Moderate maxillary and mandibular crowding. The patient has bimaxillary protrusion with severe overjet. I wanted to utilize posterior development in CuNiTi wires and future uprighting in SS wires. Both parents wanted to avoid extractions of teeth.
Torque selection: Maxillary and mandibular 2–2 low torque. Mandibular 3s standard. Maxillary left canine low torque and maxillary right cuspid standard torque.

Appointments

  1. 1. On bonding day I chose to engage all teeth on 0.014 CuNiTi wires, with the exception of the maxillary left lateral incisor. I did use bite turbos to disarticulate the bite and used interarch elastics with Class II shorty elastics with Quails from Ormco (Fig. 7).
  2. I engaged the maxillary left lateral on the 0.014 CuNiTi wire and continue Class?II elastics with quails.
  3. Four months later: As you can see, bimaxillary protrusion still exists with a mandibular Curve of Spee. However, a nice Class I is being produced. Orthodontists must be attentive to their mechanics to prevent even more protrusion. I then placed 0.018 CuNiTi on the maxillary and mandibular arches and I instructed the patient to continue to wear Class II Quails. We placed her on full time on the right and nighttime on the left (Fig. 8).
  4. At 11 months we completed our progress panorex and repositioning appointments. U18x25 CuNiTi and L17x25 NT with 20 degrees of lingual crown torque were in place for the last two months. I repositioned the maxillary right lateral incisors and mandibular lateral incisors. She wore a Delta elastic on the left and a Class II Parrot on the right.
  5. At 20 months with SS wires in place for six months. Working on expansion and retraction, and finishing elastics with Bear elastics. A sling chain was used to detorque the incisors (Fig. 9).
  6. 24 months (Fig. 10).

As you can see in both of these cases, careful mechanics were employed in the early stages with very light forces and elastics on CuNiTi wires. These mechanics were used to develop the transverse as much as possible while knowing that some protrusion would result from our decision and choice of non-extraction. Careful consideration should be taken during every appointment and resistance to the desire to increase archwires too quickly and provide overpowering forces. Once in SS wires, the patient was seen every four to six weeks with careful manipulation of the wire, not wire bending, and expansion based on the frontal view and seeing where the transverse could go. By utilizing careful choices and techniques and using the SS wires for six months or more, nice retraction was seen in the anterior segments. Optimal tissue management and great incisor inclination were seen as a result of these non-extraction treatment choices and subsequent mechanics.

Dentaltown Magazine
Author Bio
Author Dr. Todd Bovenizer is a board-certified orthodontist and the founder of Bovenizer & Baker Orthodontics. He is involved in many elite study clubs and serves on a product development team for new appliances. Bovenizer is the past president for the North Carolina Association of Orthodontists. He speaks nationally for Ormco.
 

Sponsors

Townie® Poll

Who initially places the brackets on prior to the final alignment?
  

Site Help

Sally Gross, Member Services
Phone: +1-480-445-9710
Email: sally@farranmedia.com

Follow Orthotown

Mobile App

WITH ORTHOTOWN . . . NO ORTHODONTIST WILL EVER HAVE TO PRACTICE SOLO AGAIN

WWW.ORTHOTOWN.COM - WHERE THE ORTHODONTIC COMMUNITY LIVES

9633 S. 48th Street Suite 200 • Phoenix, AZ 85044 · Phone: +1-480-598-0001 · Fax: +1-480-598-3450
©1999-2019 Orthotown, L.L.C., a division of Farran Media, L.L.C. · All Rights Reserved