Table of Contents

Continuing Education
Kois Center Case of Month
Research Update
Literature Review

Compendium

March 2011, Volume 32, Issue 2
Published by AEGIS Communications

Piezocision-Assisted Invisalign® Treatment

Ellf I. Keser, DDS, PhD; Serge Dibart, DMD

Abstract

Over the past decade the percentage of adult patients seeking orthodontic treatment has been steadily increasing.1 These adult orthodontic patients have expectations and concerns about their treatment that are different from the concerns children and adolescents may have. Sometimes the conventional mechanics that are used on children and adolescents such as head gears or metal brackets are not readily acceptable to adults. As a result, orthodontists have searched for an esthetic means of tooth correction that can especially address the needs of the older, self-conscious, or busy population.

New wire and bracket systems have helped the esthetic demands to some extent; however, some patients still are not comfortable wearing clear brackets. Lingual orthodontics, with the placement of brackets on the lingual side of the teeth, offers an alternative to the more conventional buccal placement of fixed orthodontic appliances. The lingual technique offers similar therapeutic outcomes2-4 and is more successful in meeting the patient’s esthetic demands since the appliance is invisible. Lingual bracket placement entails a substantial change in the morphology of the lingual tooth surface and of the second articulation zone, thus appearing problematic in terms of articulation and comfort.5-10 In 1998, Align Technology, Inc (www.aligntech.com) introduced Invisalign®, a series of removable polyurethane aligners, as an esthetic alternative to fixed labial braces. The Invisalign® system uses CAD/CAM stereolithographic technology to forecast treatment and fabricate many custom-made aligners from a single impression.11 Each aligner is programmed to move a tooth or a small group of teeth 0.25 mm to 0.33 mm every 14 days.12 This unique method of tooth movement has encouraged more adults to seek orthodontic therapy. In the past decade, Invisalign® has been used to treat more than 300,000 people worldwide,13,14 most of them above 19 years of age.15

Another factor important to adult patients is the length of treatment time. In recent decades major attempts have been made to shorten the length of treatment. These techniques include rapid distraction of the canines16 and corticotomy-facilitated orthodontics.17-20 In the late 1990s the Wilcko brothers added the alveolar augmentation to the corticotomies and developed the Accelerated Osteogenic Orthodontics (AOO) procedure and claimed that the orthodontic treatment time could be reduced by 75% in the majority of orthodontic cases.21 In 2007, Vercelotti and Podesta introduced the use of piezosurgery, instead of burs, in conjunction with the conventional flap elevations to create an environment conducive to rapid tooth movement.22 In 2009 one these authors (Dibart) described a new minimally invasive procedure that he called Piezocision®.23,24 This technique combines micro-incisions limited to the buccal gingiva that allow for the use of a piezoelectric knife (eg, Piezotome, Satelec/Acteon Group, www.acteongroup-products.com) to decorticate the alveolar bone and initiate the regional acceleratory phenomenon (RAP).23,24 The procedure allows for rapid tooth movement while correcting hard- and soft-tissue deficiencies when needed.23

This case report illustrates how piezocision combined with Invisalign® can be used in selected instances to satisfy the needs of esthetic- and time-conscious adult patients.

Case Report

A 28-year-old female dentist came for an orthodontic consultation. Her chief complaint was her rotated anterior teeth (Figure 1 , Figure 2 and Figure 3). She wanted a better alignment and asked for a treatment solution that would not require extensive length of treatment or brackets. She exhibited a Class I canine and molar relationship with her lower midline shifted to the right. Her maxillary central incisors were rotated and she had minimal crowding in the mandible. Conventional orthodontics with upper and lower fixed esthetic appliances were presented to her as a treatment option, but she declined. Being a dentist working in a multispecialty practice, she was familiar with both Invisalign® and piezocision and asked the authors to use these two techniques to correct the malalignment of her teeth and her midline shift.

Her Invisalign® ClinCheck® analysis revealed that she needed eight aligners in the maxilla and 16 aligners in the mandible to achieve the desired result. Some interproximal reduction (IPR) was needed to correct her lower midline shift. After careful evaluation and discussion of the ClinCheck results with the patient, the treatment plan was accepted and aligners were ordered and received in a few weeks. The piezocision surgery was performed 1 week after placement of the first set of aligners. Local anesthesia was given, and vertical interproximal incisions were made, below the interdental papilla, on the buccal aspect of the maxilla using a blade. These incisions were kept minimal, just to give access to the piezo surgical knife (Figure 4), which was then used to create the cortical alveolar incision through the gingival opening and to a depth of approximately 3 mm. The patient was sent home with a prescription for a non-steroidal anti-inflammatory drug (NSAID) and was advised to rinse twice a day with chlorhexidine. Because of the rapid and temporary demineralization that occurs after piezocision as a result of the RAP effect, the patient was asked to change her aligners every 7 days instead of 14 days. Her maxillary teeth were aligned in 8 weeks with 8 aligners. Her mandibular teeth were aligned, and her lower midline was corrected in 16 weeks with 16 aligners (Figure 5, Figure 6 and Figure 7). At the completion of the Invisalign® treatment the patient and authors were not completely satisfied with the lower incisors’ angulation and decided to use esthetic brackets to finish treatment. Her lower arch was bonded and lower incisors were up righted in 2 weeks (Figure 8 and Figure 9). Upper and lower fixed lingual retainers were used for retention at the completion of her treatment (18th week) (Figure 10, Figure 11 and Figure 12). The patient was very satisfied with the final result and the speed of her orthodontic treatment.

Discussion

Corticotomy-assisted orthodontics was developed to increase the rate of tooth movement and thus reduce treatment time.17-21 The original procedure, involving single-tooth osteotomies or corticotomies, was introduced by Kole in 1959.17 In 2001, the Wilckos developed and patented a new technique they called Accelerated Osteogenic Orthodontics (AOO), which combined bur-generated decortications and bone grafts. Although very efficient, this technique was met with some resistance from the dental community because of its invasive nature. The surgical technique used in the case described here, piezocision,23 demonstrates a similar clinical outcome when compared with the classic decortication approach but has the added advantages of being quick, minimally invasive, and less traumatic to the patient. It allows for soft-tissue grafting at the time of surgery to correct mucogingival defects if needed, as well as bone grafting in selected areas by using localized tunneling. The localized bone injury after piezocision triggers a whole cascade of localized events that are part of the RAP process, and include intensive osteoclastic as well osteogenic activities. This physiological response to injury, with its considerable amount of transient medullary bone demineralization, can be used by the therapist to move the teeth rapidly to the patient’s advantage. In the case described here there was no need for bone or soft-tissue grafting. The procedure was much simpler, as it required only piezocision of the alveolar interproximal bone without any hard- or soft-tissue grafting. No suturing was needed and the procedure was completed in 20 minutes.

The Invisalign® system is a series of clear removable appliances, similar to the clear plastic retainers that have been described by many authors.25,26 Although these plastic retainers have been modified to effect minor tooth movements, full orthodontic treatment had remained impractical because of the problem cited by Kesling in 1945: the prohibitive labor costs involved in making the set-ups.27 It was not until the advent of modern computerization that full treatment became realistic. In the Invisalign® system, if a case is suitable for treatment, the polyvinylsiloxane (PVS) impressions are scanned, a 3-dimensional model is created, and the computer performs virtual treatment using CAD/CAM technology (ClinCheck). The clinician accesses this treatment plan over the Internet and modifies it until it is acceptable. In essence, Invisalign® is like doing a set-up on a computer. Once that is done, Align Technology fabricates a series of clear plastic retainers, or “aligners,” that sequentially move the teeth at a rate of 0.25 mm to 0.33 mm every 14 days. The aligners should be worn at least 20 hours per day, but are taken out for meals and for brushing and flossing. The number of aligners needed for a particular case depends on the extent of tooth movement required. Case selection is an important step for successful Invisalign® treatment, because it has certain limitations.

In the present case, the degree of malocclusion was minor and could be resolved satisfactorily by combining Invisalign® with piezocision. The results after Invisalign® treatment at 16 weeks were quite acceptable to the patient, yet the orthodontist felt a more satisfying result could be achieved by uprighting the lower incisors. This would require using conventional orthodontics, which the patient wanted to avoid initially. The patient was told that this finishing phase of treatment, with brackets and wire, could be done quickly because, at this stage, she could still benefit from the lingering demineralization effects from the initial piezocision. As anticipated, the treatment was completed 2 weeks after placement of the esthetic brackets and wire.

The combination of a surgical technique aimed at accelerating orthodontic tooth movement and Invisalign® is not new. In 2001, Owen28 combined AOO with Invisalign® and treated his own malocclusion. He reported very satisfying results in correcting his Class I malocclusion in a short treatment time (8 weeks). This was, to the authors’ knowledge, the only report in the literature where an accelerated tooth movement procedure was combined with aligner treatment.

It should be noted that patient compliance is crucial in a piezocision treatment, especially combined with a removable appliance like Invisalign®. In the case presented, the patient was very cooperative and because the patient and authors were working in the same office the progress was easily monitored. There was no discomfort associated with the aligners or the piezocision. The patient mentioned that the aligners felt loose after 4 to 5 days of wear, therefore changing the aligners every 5 days instead of every week could be considered in future cases.

Conclusion

Piezocision is an innovative, minimally invasive technique designed to achieve rapid orthodontic tooth movement without the downside of extensive and traumatic conventional surgical approaches. This novel technique can be combined with different orthodontic treatment modalities to satisfy today’s adult patient population. This particular case report illustrates how piezocision can be combined with Invisalign® in selected cases to produce outcomes that are both timely and satisfactory.

Disclosure

Dr. Dibart has received grant support from Acteon Group.

References

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About the Authors

Elif I. Keser, DDS, PhD
Adjunct Assistant Professor
Department of Orthodontics
Boston University
Henry M. Goldman School of Dental Medicine
Boston, Massachusetts
Private Practice
Istanbul, Turkey

Serge Dibart, DMD
Professor and Program Director,
Department of Periodontology and Oral Biology
Boston University
Henry M. Goldman School of Dental Medicine
Boston, Massachusetts