Dr. Ed Lin describes treating a case with Class II, division II, subdivision right with right posterior crossbite and maxillary cant

 

Technology, technology, technology! We are truly living in a technological age. No matter where we look, we see the impacts of technology in every facet of our daily lives from WiFi, to iPhones®, iPods®, iPads®, BlackBerries®, 3D HD TVs, Blu-Ray® players, digital cameras, digital camcorders, laptops—the list goes on and on. The same can be said about our esteemed profession of orthodontics. If someone had told us late-‘90s orthodontic residency program graduates that we would be practicing orthodontics in the 3-D world, not only diagnosing and treatment planning, but also actively treating our patients with 3-D CAD/CAM software applications in combination with robotics, we would have thought they were crazy! How far we have come in only 11 years. This article discusses a clinical case utilizing four advanced technologies that have without a doubt made a major impact on the way many of us practice clinical orthodontics every day: SureSmile® (Orametrix), cone-beam computed tomography (CBCT; i-CAT®, Imaging Sciences International), Dolphin® 3D (Patterson Dental Supply), and temporary anchorage devices (TADs).

Patient information

The patient presented at her new patient examination on 4/29/08 as a healthy 23-year, 4-month-old adult woman. She stated that her chief goal was to have a nicer smile for her wedding in August 2009. The patient is a dental assistant, and she has a much higher orthodontic IQ than our average orthodontic patient. She asked if I could remove her braces for the wedding, and then put them back on again after her honeymoon, which I readily agreed to do.

Diagnosis and etiology

Intraoral examination revealed a Class II, division II, subdivision right molar and canine relationship (Figure 1). She had an open-bite tendency with an overbite (OB) of 5%, and her overjet (OJ) was 1 mm. There was an increased upper and lower curve of Spee, and minor lower incisal wear due to her OB and OJ relationship. Her UR2 and UL2 were both narrow and asymmetrical in clinical crown width. Arch-length deficiencies were 2 mm in her maxillary arch and 3 mm in her mandibular arch. Both maxillary and mandibular arch forms were asymmetrical and tapered. There was a right posterior crossbite present due to her asymmetrical and tapered maxillary and mandibular arches. Periodontal evaluation revealed normal and healthy gingival tissue with no recession present.

Frontal facial evaluation revealed a symmetrical and balanced facial pattern for her upper and middle facial third heights. There was a slightly asymmetrical lower facial third height with her right gonial angle slightly lower than her left gonial angle. Profile facial evaluation revealed a straight profile with a slightly prominent chin. Her nasio-labial angle was 120 degrees, and both upper and lower lips were normal and competent at repose. A frontal smile evaluation revealed acceptable upper and lower smile lines with buccal corridors present. A 2-mm maxillary cant down to her right was also present (Figure 2).

 

Cephalometric analysis revealed a Class I skeletal relationship with ANB = 3. It also revealed a dolichocephalic facial pattern with a high MPA = 38. Her upper and lower incisors were both retroclined with U1-SN = 91 degrees and IMPA = 86 degrees (Figure 3).
Panoramic evaluation revealed that all third molars had been extracted (Figure 4). Alveolar bone height in both maxillary and mandibular arches looked healthy and within normal limits. There were no other significant findings present.

Treatment summary

The patient was given two options for treatment. The first, and ideal, option consisted of treatment with full, fixed orthodontic appliances in combination with two-jaw orthognathic surgery for correction of her maxillary cant, asymmetrical Class II, and her right posterior crossbite. The second option consisted of treatment with full fixed orthodontic appliances in combination with two upper TADs for correction of her maxillary cant and right posterior crossbite. The patient was told that with the second option for treatment, there could be some compromises to her occlusion due to the fact that I would be trying to correct her skeletal problems without orthognathic surgery.



The patient stated that she was not interested in the surgical option and chose to be treated with the second treatment option. With her knowledge of orthodontic therapy, she also requested to be treated with SureSmile® and ceramic fixed appliances to meet her desire for an esthetic orthodontic appliance in the shortest treatment time possible. Because she was getting married in a year, plans were made to remove her upper fixed appliances prior to her wedding and to place them on again after the honeymoon. An estimated treatment time of 24-30 months was given due to the complexity of her case.

In July 2008, 0.018 In-Ovation® C and In-Ovation®R (Dentsply GAC) fixed appliances were placed for U7-7 and L7-7 in combination with 0.018 Clarity™ fixed appliances (3M Unitek) for her L5s and L4s using an indirect bonding technique. Bioforce® Sentalloy® 0.016 x 0.016 wires (Dentsply GAC) were placed in both maxillary and mandibular arches. The upper arch wire was not placed into her U7s to prevent super-eruption of her U7s and bite opening. Posterior bite turbos were placed on her LL7 and LR7 utilizing Twinky Star (Voco) for control of her open-bite tendency. On the same day of her full-bonding appointment, utilizing the i-CAT® scan taken at her initial records appointment in combination with Dolphin® 3D, it was determined to place two upper TADs between her UR6/UR5 and UR4/UR3. Closed elastomeric chains (American Orthodontics) were placed utilizing direct anchorage from the posterior TAD to her UR6 and the anterior TAD to her UR4. Two goals would be accomplished by placing the elastomeric chains in this configuration: (1) torquing the buccal posterior segments out labially would address the right posterior crossbite correction; and (2) intrusion of her upper right posterior dentition would address her maxillary cant correction. Six weeks later, the patient was seen for her regular appointment, and the closed elastomeric chains were moved from the two TADs to the UR6 and UR3.

One month later, the patient began the SureSmile® process. Her upper and lower arch wires were removed, and the In-Ovation® C and In-Ovation® R bracket doors were closed. Upper and lower incisal recontouring was performed to give balance and symmetry to her incisal edges (Figure 5). An i-CAT®-SureSmile® scan (8-cm height at 0.2 voxel setting for 20 seconds) was then taken with a wax bite with the condyle seated in the glenoid fossa and leaving the patient’s bite open ~3 mm (Figure 5). Bioforce® Sentalloy® 0.018 x 0.018 wires were then placed in both maxillary and mandibular arches, and ligature ties were placed from the two TADs to her UR6 and UR3. The patient was instructed to wear elastics in a zig-zag configuration on her right side (5/8”, 3.5 oz for LR6-UR5-LR5-UR4-LR4) and vertical elastics on her left side (3/16”, 3.5 oz for UR3-LR4-LR3). By leaving the patient’s bite open, SureSmile® is able to utilize the CBCT DICOM data to create the clinical crown anatomy as well as the root anatomy for the patient’s SureSmile® virtual models. The clinician is then able to correct the patient’s malocclusion using SureSmile® 3D software applications. A tooth size discrepancy was diagnosed using SureSmile’s software as well, and spaces were positioned on the distal of her UR2, and UL2. The patient’s SureSmile® plan was completed, and her SureSmile® wires were ordered to be bent utilizing SureSmile’s proprietary software and robots (Figure 6).

Six weeks later, 0.0176 x 0.0252 SureSmile® CuNiTi wires were inserted in both maxillary and mandibular arches. The patient was instructed to wear 5/16”, 3.5-oz Class II elastics from her LR6-UR3-LR4 and 3/16”, 3.5-oz vertical elastics from UL3-UL4-LL3 to be worn full-time (Figure 7). Two months later, the patient returned, and photos were taken (Figure 8). All elastics were discontinued at this appointment. Her dentist had requested that spaces be placed on the mesial and distal of her UR2, UL2, and coil springs were placed to accomplish this.

Eight weeks later, photos were taken again to track treatment progress, and the spaces for her UR2, UL2 were checked so that each tooth would be equal to 7.5 mm (Figure 9). Six weeks later, the patient returned to have her fixed appliances debonded, and she was moved into retention with an Essix ACE® retainer with full-time wear and an L3-3 fixed lingual splint (Figure 10). Both of her upper TADs were removed at this appointment as well. Four months later, the patient returned for final records after completion of composite veneers for UR2, UL2, and retention wear of her Essix ACE® retainer was reduced to bedtime only (Figures 11-13).

Total treatment time for this patient was 9 months and 1 day. The total number of appointments from the initial bonding appointment to her debond appointment was nine, including one emergency appointment to replace a bracket. Her treatment was actually completed 4 months before her wedding.

Summary and conclusions

Two alternative treatment options for this patient could have been: (1) full orthodontic treatment with or without SureSmile® in combination with orthognathic surgery; and (2) full orthodontic treatment without SureSmile® in combination with TADs.
I chose to utilize the i-CAT®, Dolphin 3D, TADs, and SureSmile® technologies within my treatment plan because I personally believe that these four technologies greatly improve my capability to diagnose and treatment plan (i-CAT® and Dolphin® 3D), as well as deliver active therapeutic care (TADs, i-CAT®, and SureSmile®).



The advantages of 3-D imaging with CBCT are numerous.1 Studies have shown that radiation exposure is significantly lower for CBCT when compared to medical CT imaging.2 3-D imaging also provides clinicians with the ability to enhance the precision and effectiveness of their diagnoses and treatment planning.3-7 Obtaining an i-CAT® scan at the initial records appointment for this patient enabled precise determination of the most favorable positions for TAD placement for correction of her maxillary cant without placing the patient at risk for root perforation or delaying placement of the TADs for at least a couple of months while creating space between the roots. This is clearly illustrated by the red arrows from the 3-D right lateral view of her maxilla and maxillary dentition (Figure 14) and where the TADs were actually placed (Figure 15). As a result, correction of her maxillary cant was accomplished in just 2 months and 8 days after initiation of her orthodontic treatment.

As clinicians, we must understand that radiation exposure with CBCT for the patient is slightly higher than conventional 2-D dental radiography. Three i-CAT® scans were taken for this patient (initial records, 4/29/08; SureSmile®/i-CAT® scan, 9/16/08; and final records, 7/27/09). At the settings that were used, the radiation exposure was ~70 µSv per scan for the initial and final record scans, and ~100 µSv for the SureSmile®/i-CAT® scan.* The three combined scans resulted in radiation exposure to the patient of ~240 µSv over a period of 15 months. This is only slightly higher than a full-mouth digital series of x-rays or F-speed film (170 µSv), and significantly less than a medical CT (Ludlow et al2). Clinicians must always weigh the risks versus the benefits whenever recommending any type of radiographic imaging. It is this author’s personal opinion that the benefits the patient derived from 3-D imaging for diagnosis and treatment planning, combined with consequently being able to achieve the final results so rapidly, far outweigh the risk of the low level of radiation exposure over this 15-month period of treatment time. It should be noted that before each i-CAT® scan, the patient was provided with an informed consent form explaining both the risks and the benefits of CBCT, which is a standard protocol for any patient in our practice.



The advantages of using SureSmile® have been substantiated in two recent and separate studies, with SureSmile® cases grading better with American Board of Orthodontics (ABO) scores and completing treatment with an average of 25% reduced treatment times in comparison to conventional orthodontics.8,9 In this author’s opinion, the advantages of using SureSmile® in combination with i-CAT® to create the SureSmile® 3-D CAD/CAM models and to evaluate malocclusion and root positions are invaluable. Utilizing SureSmile’s software applications, it was possible to precisely determine in 3-D the dental and root alignment issues that were still present (Figures 5 and 16), and address them with a customized treatment plan that repositioned the patient’s dentition (both crowns and roots) to an ideal occlusion (Figure 17). These movements were measured very precisely, to within 1 degree and 0.1 mm of accuracy. The 3-D CAD/CAM models facilitated the evaluation of ideal root positioning and prevented root interferences and restriction of tooth movement while aligning the teeth (Figures 18 and 19). Several studies have shown that evaluation of root positions utilizing a 2-D panoramic radiograph is an inaccurate procedure.10 Using SureSmile® in combination with CBCT provided a significant advantage in this case. Following the SureSmile® treatment plan, a customized SureSmile®.017 × .025 wire CuNiTi was then fabricated.

Using these types of technologies for treatment planning and designing cases requires unique skill sets. Developing these skills helps clinicians achieve the types of results seen in this case. Although I have been using all of these technologies for at least 4 years, whenever I review cases, the resulting clinical effectiveness is amazing. These technologies enable us to offer alternative treatment options to orthognathic surgery to more patients without having to accept compromises in their occlusion. In this day and age of technology, we can only wonder and eagerly anticipate what new technologies will be available to orthodontists next.

Data provided by Imaging Sciences International

Bio

Ed Lin, DDS, is a full-time practicing orthodontist, and is one of three partners at Orthodontic Specialists of Green Bay (OSGB), a private group practice in Green Bay, WI. He also is one of two partners at Apple Creek Orthodontics (ACO) in Appleton, WI. Dr. Lin received both his dental and orthodontic degrees from Northwestern University Dental School (DDS, 1995 and MS, 1999). Both OSGB and ACO are completely digital practices and have been at the forefront of the orthodontic profession in implementing new technologies. Dr. Lin is an internationally recognized speaker and has lectured at several orthodontic residency programs across the United States. He is on both the Clinical and Faculty Advisory Boards of SureSmile®. He also serves on the Editorial Advisory Boards for both Orthodontic Practice US and OrthoTown.

References

References
1. Mah J, Hatcher DC (2003) Current status and future needs in craniofacial imaging. Orthod Craniofac Res 6(1):10-16.

2. Ludlow J, Ivanovic M (2008) Comparative dosimetry of dental CBCT devices and 64-slice CT for oral and maxillofacial radiology. Oral Surg Oral Med Oral Pathol Oral Radiol Endod July:107-110.  

3. Redmond R, Huang J, Bumann A, et al (2005) The cutting edge – three-dimensional radiographic analysis in orthodontics. J Clin Orthod 39:421-428.

4. Haney E, Gansky S, Lee  J, et al (2010) Comparative analysis of traditional radiographs and cone-beam computed tomography volumetric images in the diagnosis and treatment planning of maxillary impacted canines. Am  J Orthod 137:590-597.

5. Granlund C, Lith A, Molander B, et al (2011) Frequency of errors and pathology in panoramic images of young orthodontic patients. Eur J Orthod 2011; epub April 21, 2011 doi:1093/ejo/cjr013.

6. Cha J-Y, Mah J, Sinclair P (2007) Incidental findings in the maxillofacial area with 3-dimensional cone-beam imaging. Am J Orthod 132:7-14.

7. Ludlow J; Gubler M; Cevidanes L, et al (2009) Precision of cephalometric landmark identification: Cone-beam computed tomography vs conventional cephalometric views. Am J Orthod Dentofacial Orthop 136(3):312.

8. Saxe A; Louie L; Mah J (2009) Efficiency and effectiveness of SureSmile. World J Orthod 11:16-22.

9. Alford T; Roberts E; Hartsfiled J;et al (2011) Clinical outcomes for patients finished with SureSmile method compared with conventional fixed orthodontic therapy. Angle Orthod 81:383-388.

10. Leuzinger M, Dudic A, Giannopolou C, et al (2010) Root-contact evaluation by panoramic radiography and cone-beam computed tomography of super-high resolution. Am J Orthod 137:389-392.