Orthodontics Treatment with Invisalign

Tarek El-Bialy, Donna Galante, Sam Daher

Faculty of Medicine and Dentistry 7-020D Katz Group Centre for Pharmacy and Health Research University of Alberta, Edmonton, Alberta T6G 2E, Canada

Abstract

Surgical orthodontic treatment is usually required in cases having severe skeletal mal-relationships and malocclusion that cannot be resolved solely by orthodontic treatment. In managing surgical orthodontic cases, pre-surgical orthodontic treatment usually aims at coordinating both dental arches, eliminating dental compensation due to the skeletal mal-relationship if present and to eliminate any dental interferences once dental arches are occluding together after the skeletal mal-relationship is corrected by surgical intervention. Post-surgical orthodontic treatment usually aims at finishing and detailing dental arch relationships and ensure that no interferences exist. Traditionally, pre-surgical and post-surgical orthodontic treatments are usually achieved by regular fixed orthodontic appliances and pre-surgical orthodontics usually require having the patients wearing heavy archwires in order to be used for inter-maxillary fixation after surgery. The introduction of clear aligners in surgical orthodontics was initially somehow not well-received by orthodontists and oral surgeons due to the fact that rigid archwires are needed before surgery and clear aligners may have limitations on what can be done in terms of preparing cases with skeletal mal-relationships for orthognathic surgeries. The present chapter will shed the light on surgical orthodontic cases that were treated solely by clear aligners before and after orthognathic surgeries as well as describe steps in management of such cases using clear aligners.

Keywords: Clear aligners, Decompensation, Diagnosis, Orthodontics, Post-surgical, Pre-surgical, Stability, Surgical orthodontics, Temporary anchorage devices, Treatment planning.


* Corresponding author Tarek El-Bialy: Faculty of Medicine and Dentistry 7-020D Katz Group Centre for Pharmacy and Health Research University of Alberta, Edmonton, Alberta T6G 2E, Canada; E-mail: telbialy@ualberta.ca.

Introduction

Surgical orthodontic correction of dentofacial deformities including jaw mal-relationship aims to improve facial aesthetic and function in these cases [1]. A successful outcome of orthognathic surgery depends on the planning and execut-

ion of orthodontic and surgical techniques [25]. Surgical orthodontic planning involves model surgery, traditional cephalometric prediction as well as photographic prediction or utilization of computerized cephalometric/photo-graphic predictions [6, 7]. Model surgical prediction suffers from potential errors including model mounting of jaw relationship by face bow/bite transfer. In complex cases, dental compensation and crowding may necessitate extraction of teeth. In class II skeletal cases when extraction is required for decompensation and relieving crowding is needed, the extraction pattern usually involves lower first premolars and upper second premolars. The reverse pattern is usually the case in severe skeletal class III. However, in many cases where dental compensation is not too severe, or when crowding is not moderate or severe, extraction may not be necessary for pre-surgical orthodontics phase. Many cases can be treated pre-surgically by arch development (expansion) and incisors torque as well as interproximal reduction.

Align technology uses a digital diagnostic set up, using Clincheck® software, that allows the clinician to plan and predict tooth alignment, dental arch relationships, as well as viewing dental occlusion from different aspects that are normally hard to see or evaluate using plaster models. In addition, it helps clinicians with planning the treatment as well as mitigating dental interferences before they occur.

Case 1

This is a 27 year-old female that was presented with a chief complaint that she had overbite and a small chin. Clinical examination and clinical records (Figs. 12.1 & 12.2) revealed the following findings:

  1. Convex profile with recessive chin and relatively large nose and increased nasolabial angle.
  2. Class II skeletal and dental relationships due to mandibular retrognathism
  3. ANB angle = 6.6°
  4. Overjet = 8 mm and overbite is 80%
  5. Increased curve of Spee
  6. Minimum crowding of the upper arch that was narrow (tapered) and no crowding in the lower dental arch.
  7. Wisdom teeth were missing and no major dental anomalies.

Fig. (12.1))
Initial clinical records of patient #1. Extraoral photos show patient had a convex profile due to recessive chin and relatively large nose. Class II division 1 malocclusion with increased curve of Spee.

Fig. (12.2))
Initial radiographs showing skeletal Class II relation.

Treatment Objectives

  1. Improve patient’s profile by advancing her mandible via bilateral sagittal split osteotomy (BSSO) and using temporary anchorage devices (TADs) for elastic wear.
  2. Improve the patient’s occlusion to full class I molars and canines
  3. Improve patient’s overjet and curve of Spee.
  4. Relieve crowding.

Fig. (12.3))
Pre-surgical records showing upper arch expansion and relieve of the patient’s upper crowding.

Treatment Progress

  1. Patient had pre-surgical orthodontics utilizing Invisalign that included 21 upper and 22 lower aligners.
  2. Curve of Spee was improved by intruding lower incisors and extruding lower premolars by using horizontal attachments on the lower premolars.
  3. Pre-surgical records (Fig. 12.3) show proper upper incisors alignment, upper arch was expanded to allow for mandibular forward positioning by BSSO.
  4. Immediate post-surgical records (Fig. 12.4 and 12.5) show improvement of the patient’s profile, chin prominence, class I molars and canines and inter-maxillary fixation was performed using mini-screws (four in each arch for inter-maxillary elastics) (Fig. 12.6).
  5. According to the recommendation by Dr. Daher, elastics protocol post-surgery was worn by the patient as follows:
    1. Elastics: Upper to Lower TAD’s:
    2. Size: 5/16” (8mm), 3 oz (100 grams), full-time
    3. 2-3 weeks in total
    4. Wear U & L aligners full-time
  6. Reasons for elastics are described by Proffit [8] as follows: “Light vertical elastics are needed initially, not so much for the tooth movement but to override proprioceptive impulses from the teeth that otherwise would cause the patient to seek a new position of maximum intercuspation” [8].
  7. The duration for 2-3 weeks post-surgery of elastics wear has been reported by Proffit [9] to allow for early function and early finishing of the case orthodontically.
  8. Post-surgical orthodontic treatment involves continuous level of the curve of Spee, utilizing buttons bonded to the lower premolars and molars that can be extruded using vertical elastics to the upper TADs (Figs. 12.712.9).
  9. Settling posterior occlusion can also be achieved by adding buccal buttons to the upper molars for vertical posterior elastics between buttons bonded to upper and lower posterior teeth (Fig. 12.10).

Fig. (12.4))
Patient’s photographs at 11th day post-surgery showing TADs in place for posterior teeth settling.

Fig. (12.5))
Post-surgical radiographs showing correction of the skeletal Class II relation.

Fig. (12.6))
Intraoral photographs and clincheck showing TADS and elastic pattern.

  1. Care should be taken not to overdo elastics wear in this pattern. It should be noted that applying vertical elastics from the buccal surface can rotate upper and lower molars’ crowns lingually as the lines of action of these forces are buccal to the center of resistances of upper and lower posterior teeth and this leads to a moment that tends to rotate the posterior teeth crowns lingually. This may be advantageous in cases where upper and lower molars are tipped buccally either by pre-surgical orthodontic expansion or due to pre-existing position of these teeth uprighted. Applying the vertical elastics in these cases can provide normal torque of the posterior teeth as described by Andrews when he explained the need for lingual crown torque in adult normal occlusion [10]. If however a case shows normal posterior teeth crown angulation (torque), vertical elastics may be applied both buccally and lingually in order to maintain teeth axial inclination.
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May 6, 2017 | Posted by in Orthodontics | Comments Off on Orthodontics Treatment with Invisalign
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