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THE USE OF PROPEL TO INCREASE INCREASING THE RATE OF ALIGNER PROGRESSION THE RATE OF ALIGNER PROGRESSION T Dr. Thomas S. Shipley discusses increasing the bone remodeling rate for more rapid aligner progression he use of clear aligners has gained broad accep- ing intermittent orthodontic forces on the dentition, which tance as an alternative way to orthodontically move could actually slow the overall progress of the movement. the dentition. As the orthodontic community becomes Increasing the rate of bone remodeling is the key more familiar with this modality of treatment, questions to being able to change aligners at a more rapid pace, arise as to best clinical practices to achieve optimal re- therefore, decreasing overall treatment time. sults. One area of interest is how often to change align- A female patient presented at age 21 with a mild ers. The Invisalign® System suggests the optimal time Class II, Division 2 malocclusion. Moderate upper and to change from one aligner to the next, with good patient lower dental crowding existed with a 60% deep bite compliance, is 2 weeks. The aligner system and the and negatively inclined upper incisors. The patient’s amount of movement prescribed in each aligner determine chief concern was the rotation of the upper left lateral how frequently the patient is required to change aligners in incisor. The CBCT showed good root parallelism and the sequence. Changing aligners at a faster rate than the normal development of the dentition (Figures 1-7). velocity of tooth movement would be one cause of aligners not “tracking” over time. This rate of aligner change is a limiting factor in the overall case completion time. In more difficult cases, the number of aligners prescribed may reach as many as 40 to 60 aligners, with even more in the most difficult cases. To the patient, who can quickly do the math, and to the clinician, who Figure 1 knows “refinement” or “auxiliary treatment” has not even been accounted for yet, the future of the orthodontic treatment becomes daunting. In these cases, or with any case, where increased velocity of tooth movement is desired, a way to change aligners at a more rapid pace becomes attractive. Figure 2 Figure 3 Figure 4 Figure 5 The rate of tooth movement is dependent on the rate of the physiologic process of bone remodeling.1,2 If this rate of bone remodeling is increased, then the rate at which aligners should be changed increases also. Failing to change the aligners fast enough to coincide with the velocity of tooth movement would be equivalent to plac1 Orthodontic Practice US medical device that creates Micro-Osteoperforations (MOPs). These MOPs stimulate a cytokine response in the patient’s alveolar bone during orthodontic treatment Figure 6 (Figures 10- 11).3 MOPs Figure 7 reduce overall orthodontic treatment time by harnessing the body’s own biology to increase the rate of tooth movement and release challenging movements. 4 This in- Figure 8 office technique can be Figure 9 performed chairside in The treatment plan was developed to use clear minutes during a patient’s regularly scheduled office aligners in conjunction with Class II elastics to resolve visit and can be used in conjunction with any type of the dental crowding, slightly procline the upper and fixed or removable orthodontic appliance. Micro-Os- lower incisors, correct the deep bite, and improve the teoperforations with Propel can be used to advance Class II dental relationship. Once the treatment plan was finalized, the resultant prescription for aligners was 43 upper and lower aligners. The aligners consisted of 43 active maxillary aligners, and 23 active lower aligners, followed by 20 lower passive aligners (Figures 8-9). Cuts were made in the upper aligners near the maxillary canines to create hooks for Class II elastics and cutouts in the lower aligners in the buccogingival area of the lower second molars to allow for Class II button hooks to be bonded Figure 10 (Figure 14). No interproximal reduction was prescribed. The patient desired to finish treatment faster than 86 weeks! The clinician was concerned that this treatment did not allow much time for refinements and detailing which may be needed. Both agreed that Propel would be an appropriate way to speed the orthodontic treatment. Propel is a technique performed with the patented Figure 11 FDA Registered Class 1 510(k)-exempt disposable 2 Orthodontic Practice US the treatment of any malocclusions, including, but not limited to, crowding, space closures, molar uprighting, rotations, intrusions, and extrusions. Aligners 1 and 2 were delivered at the initial appointment. The patient was Figure 12 Figure 13 Figure 14 Figure 15 told to wear each aligner for 2 weeks and return in 4 weeks for placement of attachments. At the 4-week return appointment, aligner 3 was delivered, attachments were placed, and Class II elastics com- menced. No Propel was used for the first 6 weeks of treatment. A regular tray progression of 2 weeks per was little discomfort of the procedure other than mild tray was used. There are several advantages to start- pressure between the teeth in a few areas. A post-Pro- ing at this pace. The patient has ample time to adapt pel CBCT was taken, which shows the location of the to wearing the trays and to learn how to be compliant. maxillary left MOPs (see image). The patient rinsed Treatment progressed at a slower pace, not to again with chlorhexidine gluconate after the procedure overburden the patient with learning to wear the trays, and was asked to wear the aligners at a progression of having attachments placed, beginning elastic wear, 3 days each. and Propel all at the same time. In addition, the clini- With such a rapid pace of aligner progression, cian is given an opportunity to gauge patient compli- close monitoring by the clinician is needed to ensure ance before beginning Propel. The enhanced cytokine patient compliance and good aligner “tracking.” If the response with the MOPs would be of little benefit with- rate of aligner progression exceeds actual tooth move- out good patient compliance. ment, it will be apparent due to poor aligner fit. Aligner progression may be slowed, if needed, based on how Six weeks into treatment, Propel was initiated. The the patient presents on follow-up visits. use of local infiltration anesthesia (2% Lidocaine with The patient was seen 2 weeks later and was 1:100,000 epinephrine) was employed. “Profound” topical anesthesia may instead be used. The patient now beginning aligner 9. As shown in the photos, rinsed twice with chlorhexidine gluconate and expec- the aligners were fitting the dentition perfectly (good torated. MOPs were placed inter-radicularly using the “tracking”). This indicated that the progression at Propel device as follows: 3 days per aligner was appropriate for this patient (Figures 16-18). In addition, the soft tissue had com- Three MOPs mesial and distal of the maxillary lateral incisors, and two MOPs mesial and distal of the pletely healed with no signs of trauma at 2 weeks lower incisors (Figures 12-13). She stated that there (Figures 19-20). 3 Orthodontic Practice US Figure 16 Figure 17 Figure 18 Figure 19 Figure 20 The patient was seen again 2 weeks later (4 of 14 weeks. No refinement or detailing was needed weeks post-Propel). At this time, she was just begin- for the lower arch. ning tray 14, and a CBCT was taken that shows the More aligners were delivered, and Class II elastics MOPs slightly smaller, but still present (Figure 21). were continued. The patient returned every 4 weeks Again, the “tracking” of the aligners was still excellent. forward until completion of treatment of the maxillary A 4-week interval was now chosen, continuing at 3 orthodontic treatment. The aligner progression con- days per aligner. tinued at 3 days per aligner. The patient continued to Four weeks later, the patient was wearing the change the lower passive aligners at the same pace. 23rd aligners. The aligners were still “tracking” per- At 23 weeks, treatment was completed on the up- fectly, and treatment was completed on the lower arch. per dentition after the use of 43 upper aligners. No Complete resolution of the lower dental crowding was refinement aligners were needed. Attachments were achieved as prescribed using 23 aligners over a period removed, and retainers with similar Class II elastic hooks and cutouts were fabricated. The bonded buccal hooks on the lower 2nd molars were left for 6 months, for the continued use of class II elastics for 12 hours per night as part of the retention protocol. Otherwise, the clear removable retainers were worn according to the clinician’s normal retention protocol. Evaluation of the final records shows adequate inclination of the upper and lower incisors to allow for Figure 21 Figure 22 Figure 23 Figure 24 4 Orthodontic Practice US better anterior guidance, which was achieved by upper and lower dental rotations. The post-treatment CBCT, anterior labial crown torque and lower incisor proclina- taken 6 months post-Propel, shows the MOPs almost tion aided by the use of Class II elastics. In addition, completely healed (Figure 25). the overbite was corrected to an appropriate 30%. The The final results show that Propel is a good ap- patient’s chief concern of the rotated upper left lateral proach to increasing the rate of clear aligner pro- incisor was completely corrected to her satisfaction, gression by increasing the rate of bone remodeling. along with complete resolution of the remaining upper Treatment time was reduced over 70% in this case as Figure 25 5 Orthodontic Practice US compared to a typical 2 week interval aligner case. The overall amount of appointments were reduced from 20+ to 8. More research is needed to gain a better understanding of the exact rate of tray progression that should be used. A clinician new to this treatment modality should consider starting at a slower progression than that shown with this case, such as 7 days per aligner. Close monitoring should be employed, and adjustments may be made to the rate of progression based on the clinical results for each patient. REFERENCES Treatment Progression 1. Henneman S, Von den Hoff JW, Maltha JC. Mechanobiology of tooth movement. Eur J Orthod. 2008;30(3):299-306. 2. Krishnan V, Davidovitch Z. On a path to unfolding the biological mechanisms of orthodontic tooth movement. J Dent Res. 2009;88(7):597-608. 3. Teixeira CC1, Khoo E, Tran J, Chartres I, Liu Y, Thant LM, Khabensky I, Gart LP, Cisneros G, Alikhani M. Cytokine expression and accelerated tooth movement. J Dent Res. 2010;89(10):11351141. 4. Khoo E, Tran J, Raptis M, Teixeira CC, Alikhani M, Abey M. Accelerated Orthodontic Treatment [research paper]. New York: New York University; 2011. 6 Orthodontic Practice US ABOUT THE AUTHOR Thomas Shipley, DMD, MS, received his Bachelor of Science degree in Business Management from Brigham Young University and went on to earn his doctorate from the University of Kentucky College of Dentistry. Dr. Shipley completed a master’s program in orthodontics at West Virginia University. He maintains a full-time private practice in Peoria, Arizona, and is an Adjunct Professor at Arizona School of Dentistry, Department of Orthodontics in Mesa, Arizona. Dr. Shipley maintains membership in numerous professional organizations, such as the American Dental Association, the Arizona Dental Association, the American Association of Orthodontics, the Pacific Coast Society, the Comprehensive Care Continuum Study Club; and he is the coordinator of the International Dental Ed Continuing Education Study Group for the Northwest Phoenix area. He is board certified by the American Board of Orthodontics. 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Approval does not imply acceptance by a state or provincial board of dentistry or AGD endorsement. 6/1/13 to 5/31/16 Provider #306446 Catapult Group,LLC LLCis is Academy of General Dentistry Approved PACE Program Provider Catapult Group, anan Academy of General Dentisry Approved PACE Program FAGD/MA Approval does not imply acceptance by anot state or acceptance provincial board of dentistry or AGD endorsement. Provider FAGD/MAGD Credit. Approval does imply by a state or 6/1/13 to 5/31/16 #306446 provincial board of Provider dentistry or AGD endorsement. 6/1/13 to 5/31/16 Provider #306446 Catapult Group designates this activity for 1 continuing education credit. Original Release Date: March 2014 Expiration Date: March 2017 Please visit www.catapultuniversity.com to take the CE quiz and obtain your certificate of completion. Sponsored by Propel R Intended Audience: Orthodontists, Dentists and all Dental Professionals Subject Code 370 7 Orthodontic Practice US