Efficiency, three-dimensional planning and prediction of the orthodontic treatment with the Invisalign® System: case report

The increasing technology improvement applied to softwares for the diagnosis, treatment and prediction in Orthodontics and Facial Orthopedics, has made possible the creation of virtual threedimensional casts of the dental arches by the digital scanning of a patient’s orthodontic impressions. These precise virtual models can be manipulated with a software, creating successive (sequential) dental movements of an initial stage of the malocclusion (the patient’s clinical situation) in order to achieve a desirable final tooth positioning and a normal occlusion. Physical casts of each tooth movement stage can be created by the stereolitographic process, allowing the production of a series of fine, transparent and adjusted appliances (aligners). These successive aligners must be used full time, so that they can reproduce the dental movements programmed in each stage of the virtual planning. The malocclusions, involving light to mild crowding and spacing, as well as more complex cases, have successfully been treated by the Invisalign System. Based on the diagnosis and determined therapeutic goals, this is an efficient system (material and method) and an alternative for the orthodontic treatment of patients during the full permanent dentition phase. This clinical case report aims at showing the efficiency and accuracy of this system concerning its virtual treatment planning and prediction in comparison to the clinical outcomes (real treatment). Key-words: Orthodontic Treatment. Invisalign System. Three-dimensional Image (3D). * Specialists in Orthodontics-Facial Orthopedics, Professors of the Orthodontic-Facial Orthopedics Dept., School of Dentistry, Institute of Health Sciences, University Paulista – UNIP / São Paulo BRAZIL Artigo publicado na Revista Clínica de Ortodontia Dental Press, v.2 n. 2 abril/maio de 2003. Tradução: Rosemary Piancó Gulla Revisão: Dra. Rosely Suguino Revisão final e técnica: Rolf M. Faltin Efficiency, three-dimensional planning and prediction of the orthodontic treatment with the Invisalign® System: case report 62 • R Clín Ortodon Dental Press, Maringá, v. 2, n. 2, p. 61-71 abr./maio 2003 Rolf M. Faltin, Márcia A. A. de Almeida, Carlos A. Kessner, Kurt Faltin Júnior R Clín Ortodon Dental Press, Maringá, v. 2, n. 2, p. 61-71 abr./maio 2003 • 63 INTRODUCTION The dental movement concept through sequential stages individually planned by a “set-up” in casts, and the use of elastomeric appliances have initially been suggested by Kesling and later on by Ponitz, and others, such as McNamara, Kramer, Juenker, Sheridan, Ledoux, McMinn, Rinchuse and Rinchuse, and Lindauer and Schoff. The limitation of these methods described until then was the small magnitude of the changes achieved, associated to the technical difficulties, among them, to manually subdivide in stages a movement desired in several small movements (unique or progressive “setup”). In 1998 in the USA, the Align Technology developed the Invisalign system for the orthodontic movement. This treatment method was the first one to be exclusively based on a three-dimensional digital technology (3D). A series of algorithm stages is produced to move the teeth into 0.15 to 0.25mm successive precise movements, using computer programs that manipulate the 3D (virtual) images of the individual malocclusions. For each stages stereolitographic casts are produced, over which 0.7mm thick transparent appliances (aligners) are created, fully adapted to the dental crowns. These aligners, properly numerated according to the treatment stages, must be sequentially used by the patient for an average of two weeks (14 days) each. These transparent and removable aligners juxtaposition to the dental crowns determines a singular esthetic condition with a favorable buccal hygiene concerning the malocclusions correction. A first clinical study with the Invisalign system, performed by Boyd, Miller and Vlaskalic in the Pacific University, San Francisco, California (USA), reported the success of the treatment outcomes in malocclusions involving light to mild crowding and spacing from 3 to 6mm. In a recent study, Boyd and Vlaskalic showed and discussed the clinical findings and limitations of the Invisalign system concerning the treatment of complex malocclusions, as cases with deep-bites, premolar teeth and lower incisor extraction, molar distalization, dental extrusions, open-bites, and patients showing periodontal problems. These authors discussed the esthetic advantages, comfort, hygiene and removable condition of the appliances, as well as the clinical limitations of this method, described as: the selection of cases (diagnosis), financial cost, experience with computerized planning, difficulty in obtaining wide movements, mainly extrusion and rotation, and also the cases involving impacted teeth or during the mixed dentition. The association of attachments as those bonded with composite to the enamel surface, partial cuttings in the aligners, bonding of buttons to the tooth or to the aligners, and the application of intraand inter-maxillary elastics were suggested as efficient auxilliary elements for controlling the undesirable effects and reducing the system limitations. Aim This clinical case report aims at comparing the virtual treatment determined by the orthodontist’s prescription and the three-dimensional images obtained by the Inivisalign System ClinCheck1.7 software, to the real treatment, i.e., to the clinical outcomes. The purpose was also to evaluate the clinical implications of the system for both patient and professional, as well as to discuss the efficiency, advantages and limitations of the Invisalign system as an alternative method concerning the orthodontic treatment. The Clinical Case Presentation Diagnosis The diagnosis performed based on the anamnesis, clinical and radiographic examination, evaluation of the panoramic radiograph, lateral and frontal cephalometries, and model analysis, determined the following clinical values for the patient’s signs and symptoms: male patient, leukodermas, 15-year-11month-old at the beginning of treatment, having all permanent teeth fully irrupted and in occlusion, except the third lower molars that were not present and the upper ones that were in formation. The patient showed Efficiency, three-dimensional planning and prediction of the orthodontic treatment with the Invisalign® System: case report 62 • R Clín Ortodon Dental Press, Maringá, v. 2, n. 2, p. 61-71 abr./maio 2003 Rolf M. Faltin, Márcia A. A. de Almeida, Carlos A. Kessner, Kurt Faltin Júnior R Clín Ortodon Dental Press, Maringá, v. 2, n. 2, p. 61-71 abr./maio 2003 • 63 a harmonic and mild retroverted face (dolychofacial) and a lightly convex profile. The patient had a skeletal Class I (orthognatic), Class I dental relation in the molar region and Class II canines relation (1/4cusp) with light anterior constriction of both arches. Upper anterior dental protrusion, overbite (+4.5mm), overjet (+4mm), mild anterior maxillary spacing and unleveling, premolars and canines were mesial rotated (markedly tooth 1.3), light lower anterior crowding, extrusion of right upper central incisor (tooth 1.1) and lower anterior teeth, and a slight mandibular midline deviation (1mm to the right). The functional pattern was balanced without therapeutic needs. (Fig. 1 A-H). Orthodontic therapeutic aims The main treatment goals were: a mild anterior expansion of the upper and lower dental arches, alignment and leveling of the mandibular and maxillary teeth, including the retraction of the upper anterior teeth and selective intrusion of tooth 1.1 and lower anterior teeth with axial correction (derotation) of the premolars and canines, ending in a Class I occlusal relation of the canines, with improvement of the overjet and overbite. Therapeutic materials and methods selection After making the orthodontic aims clear to both the patient and parents, the alternatives of materials and methods compatible to the treatment goals were discussed. In this clinical case, the treatment efficient possibilities were: buccal fixed orthodontics, lingual fixed orthodontics or Invisalign system. Accordingly, considering the system advantages, the compatibility with the treatment aims and the patient’s (postadolescent) refusal to use fixed appliances, the treatment was decided to be carried out with the Invisalign system. Orthodontic planning and treatment conduction with the Invisalign system Following the protocols to send the clinical case to Align Technology (Santa Clara, California, USA) the impressions and bite registration were made in PVS (polyvinylsiloxane) that together with our orthodontic planning prescription, photographic and radiographic documentation determined the “virtual treatment” performance by the scanning and manipulations with the ClinCheck 1.7 (3D) three-dimensional software. After processing (transferring) the treatment planning to the three-dimensional images of both dental arches, we received the “virtual treatment” according to our prescribed planning. This software and images were accessed and saved via internet. It is up to the orthodontist, together or not with the patient, to accept or still modify the threedimensional planning initially prescribed according to individual professional criteria and responsibility. In this phase, the final result of the virtual treatment is determined as well as the quantity of stages (aligners) necessary for the orthodontic corrections and, consequently, the estimated total treatment time (Fig. 2 A, B; 3 A, B; 4 A, B). We should consider that, the bigger the amount of teeth and extension of movement to be performed are, the bigger the quantity of successive aligners and the estimated total treatment time will be. In this clinical case, 13 upper stages (aligners) and 14 lower stages were established for this planned orthodontic correction. We opted also for the placement of vertical attachments in all canines, upper first premolars and lower premolars to obtain a better control of rotation, inclination and intrusion/extrusion by additional retention and mechanical adaptation determined by these elements. We requested an overcorrection of 2 stages for the teeth 1.3 and 4.2, due to their more unfavorable initial positioning. Therefore, we could predict an estimated total active treatment time of about 7 months with the aligners (14 aligners for 2 weeks each). This prediction is applied since the placement of the first aligner with the patient’s total compliance (full-time use of the aligners, removal only during the meals) and assiduous returns to the orthodontist when all stages through the aligners adaptation are carefully checked and then changed sequentially. Efficiency, three-dimensional planning and prediction of the orthodontic treatment with the Invisalign® System: case report 64 • R Clín Ortodon Dental Press, Maringá, v. 2, n. 2, p. 61-71 abr./maio 2003 Rolf M. Faltin, Márcia A. A. de Almeida, Carlos A. Kessner, Kurt Faltin Júnior R Clín Ortodon Dental Press, Maringá, v. 2, n. 2, p. 61-71 abr./maio 2003 • 65 After accepting the virtual planning and treatment, the phase of manufacturing the determined aligners (stages) sequence began. At the end of this process, we received (via express mail) this aligners sequence properly numbered and packed, as well as the templates for the attachments manufacturing predicted for this clinical case. The orthodontic treatment performance and outcomes with the Invisalign system The treatment began with bonding the attachment to the enamel of the predicted teeth with light-cured composite (Transbond LR, 3M), after conventional prophylaxis and etching of the involved surface. The templates determined, in negative (depressions), the attachFIGURE 1 The patient’s initial findings. (A) Initial panoramic radiograph. (B) Initial lateral ceph. (C) Initial frontal facial photograph. (D) Initial frontal facial photograph with smile. (E) Initial facial photograph of the patient’s profile. (F) Initial intra-oral photograph right side. (G) Initial intra-oral photograph frontal. (H) Initial intra-oral photograph left side. A B