Objective. During orthodontic therapy, accuracy in bonding procedures makes it easier to correct tooth alignment by decreasing the need for midcourse corrections by changing bracket positions. Indirect bonding allows the transfer of the appliance components from model casts to patient’s teeth potentially meaning shorter appointments for bracket bonding and rebonding and best comfort during chairside practice. At the same time, there has been a steady increase in requests for invisible lingual orthodontic treatment. Clinical Considerations. Accordingly, the aim of the present report is to illustrate the workflow to realize a complete digital indirect bonding for lingual brackets (2D, Forestadent). The procedure starts with intraoral digital scans, digital 3D model, and virtual bracket positioning, ending with the realization of a CAD-CAM prototyped transfer tray. A 3D intraoral scanner (True Definition, 3M) is used to create digital scans and digital models. A virtual bracket positioning is performed using software (NemoCast, Dentaurum), and a prototyped transfer tray is created by a CAD-CAM device. 2D lingual brackets were positioned inside the tray, so the appliance was bonded to the dental surface using light curing adhesive resin. Conclusions. During orthodontic treatment, CAD/CAM technology could help clinicians. Computer-constructed transfer trays can reduce clinician error and improve the everyday workflow in the office.
1. Introduction
In straight-wire orthodontic devices, ideal bracket placement can correct tooth position in the three planes of space during treatment [1]. Accuracy in bracket placement allows an efficient orthodontic treatment [2, 3].
According to Carlson and Johnson [4], there are four elements necessary for ideal bracket placement: (1) bracket base adaptation to dental surface, (2) evaluation of the rotational bracket position in relation to the occlusal plane, (3) determination of vertical position of each bracket, and (4) determination of slot angulation according to the position of the roots.
Several studies claim that indirect bonding can be more accurate than direct bonding on labial appliances with a reduction in bracket position errors in each of the three orientations examined [5–7]. Accuracy in bracket placement can also reduce the need for repositioning and can then shorten treatment time [8, 9]. These studies were related to labial and not lingual appliances and results, however, are preliminary and inconclusive about precision of positioning and total treatment time. Therefore, the reduction of chairside time can be considered the main real advantage of indirect bracket placement.
Because of its outstanding aesthetic preconditions and its growing practicability, lingual orthodontics accounts for an ever-increasing percentage of orthodontic treatments and even more studies evaluated various aspects of this technique [10–14]. Although the lingual orthodontic treatment provides several aesthetic advantages, its use has been limited due to the increased chair time and more difficult mechanical control [15]. Placement of lingual orthodontic appliance can be made easier however with new technologies such as intraoral scanning, virtual positioning of brackets, and computer-aided transfer tray manufacturing [16, 17].
Advances in CAD/CAM technology are providing new possibilities in orthodontics: the application of CAD/CAM for establishing a virtual set-up or creating transfer trays/jig [16, 17] has improved the indirect bonding workflow.
The aim of this manuscript is to illustrate the workflow to realize a complete digital indirect bonding, after an intraoral scanning and construction of a prototyped transfer tray has been created for indirect bonding.
2. Case Report2.1. Diagnosis and Aetiology
A male patient, aged 19 years old, was referred to a private orthodontic practice. He was diagnosed with a bilateral Class I canine relationship and left Class I molar relationship in the permanent dentition with a crossbite of tooth 12 (Figures 1–3). Patient chief complaint was to resolve the anterior crossbite with an invisible orthodontic appliance.
Front view of initial occlusion.
Occlusal view of initial occlusion.
3D intraoral scan view of initial occlusion.
2.2. Treatment Objectives
A lingual orthodontic appliance has been projected using a CAD/CAM digital workflow. The objective of the treatment was the resolution of anterior crossbite and retention of the case over time [18].
2.3. Treatment Alternatives
As the patient wanted to avoid conventional vestibular orthodontic treatment, a lingual orthodontic appliance was chosen. Other alternatives to conventional visible metallic attachments would have been orthodontic treatment with ceramic brackets or aligners that are both effective to obtain tooth movement [19, 20]. The patient, however, wanted to avoid ceramic brackets because of the possibility of adverse staining midtreatment and refused aligners so as to avoid treatment with removable appliances.
2.4. Treatment Progress
Written informed consent was obtained by the patient to proceed with orthodontic diagnosis and treatment. The procedure for the virtual indirect bonding started with the polishing of all dental surfaces with pumice powder; then, intraoral scan (Figure 3) was performed by a 3D intraoral scanner (True Definition, 3M, US). NemoCast software (Dentaurum, Germany) acquired the 3D models and recognized the shape of each tooth and the gum. The software realized a virtual set-up, and then, the orthodontist placed the virtual brackets on 3D virtual models according to the lingual prescription (Figure 4). The bracket placement tool ensured the precise bracket positioning according to the virtual set-up using the virtual bracket’s position on the screen. Once all brackets were positioned on the 3D models, the software allowed designing a virtual transfer tray for indirect bonding (Figure 5). A prototype of the digital transfer tray was manufactured using a rapid-prototyping machine (Figure 6). exocad software (exocad GmbH, Germany) was used to create bilateral posterior overlays to act as customized bite raisers (Figures 7 and 8).
Case planning with virtual brackets.
Virtual transfer tray.
Prototype of digital transfer tray.
Virtual customized bite raisings.
Customized bite raisings.
The patient wore protective glasses to prevent eye damage [21], and the tooth surfaces were first etched with 37% orthophosphoric acid gel (3M, US) for 30 seconds (Figure 9) followed by washing and drying. A primer (Transbond XT, 3M, US) was applied in a thin film on the etched tooth surface (Figure 10). 2D lingual brackets (Forestadent, Germany) were positioned inside the prototyped transfer tray, and an adhesive resin (Transbond XT, 3M, US) was applied over the bracket bases [22]. The brackets were then positioned in the maxilla on the upper teeth (Figure 11), using the prototyped transfer jig, and were light cured for 60 seconds each by an LED lamp (Elipar DeepCure, 3M, US). Subsequently, the transfer tray was removed by forcing a probe in the fracture line (Figures 12 and 13) and separating the jig in two halves. The fracture line was created by the CAD software in order to be useful for an easy transfer tray removal.
Etching procedure.
Adhesive application.
Device placement.
Transfer tray removal.
Wire placement.
On the lower jaw, prototyped overlay were set using an adhesive technique (Figure 14). Orthodontic treatment progress included 0.012 inch, 0.014 inch, and 0.016 inch nickel titanium archwires, followed by 0.16 stainless steel wire. The patient was checked each month, and wires were changed after 2 months each. Finally, brackets were removed, and teeth were polished (Figures 15 and 16). An upper splint and an upper Essix removable appliance were placed in order to guarantee posttreatment stabilization [23, 24].
Setting of prototyped overlays.
Front view of final occlusion.
Occlusal view of final occlusion.
3. Discussion
The virtual indirect bonding has been performed with lingual brackets with the treatment plan involving the upper teeth alone by resolution of the lateral incisor crossbite. The case has been planned with a digitalized workflow with CAD/CAM digital impression taking presenting similar efficiency as traditional impression methods in orthodontics and being more comfortable for patients [25, 26]. The position of brackets on the patient teeth (Figure 13) corresponded to the position of the same brackets on the digital 3D models (Figure 4). This can be obtained as CAD/CAM technology shows a variety of possibilities in orthodontics from study design [25] to the construction of customized splints [15] and trays for vestibular appliances [27] or for maxillofacial surgery scopes [28]. To our knowledge in the literature, there are no studies that evaluated CAD/CAM preparation of transfer trays for standard lingual appliances realized by an independent dental technical laboratory. In fact, the CAD/CAM transfer tray technique is performed only directly from the manufacturer for the use of customized lingual brackets [29], which present higher realization costs than standard lingual appliances using this technique [30].
Accurate surface imaging is required to digitally manufacture orthodontic appliances with 3D intraoral scanners reproducing precisely the image of the lingual dental surfaces [31]. Lingual surfaces vary more widely than labial surfaces [32]: for example, the bicuspid has a very slim and irregular lingual surface making bracket placement difficult. An advantage of the CAD design method is improved bonding of the lingual bracket base [33], which is important for adhesion performance [34]. The software can realize customized bracket bases which are useful in the case of bicuspids with very small lingual surfaces. Finally, the highest resolution of commercially available stereolithographic printers is about 0.3 mm, which is sufficient for providing both the bracket retention inside the prototyped transfer tray and the retention feature on the base of a stereolithographic prototype [35].
The computerized tool provides accuracy in bracket placement and significant reduction in chairside time. While software can provide precise reproducibility, orthodontists can incorporate alterations from the ideal placement to provide overcorrection of rotated teeth or accentuated tip to resist root motion in space closure [15]. Virtual indirect bonding can also be exported to other 3D CAD software, e.g., to realize customized occlusal bite raisers. Using the virtual articulation software, premature contacts on the brackets can also be eliminated.
Indirect bonding is currently used with 3D customized lingual brackets, and it is not used with the 2D lingual appliance, as the brackets can be placed directly. Moreover, 2D lingual brackets are a low cost option for mild cases where only the 1st- and 2nd-order corrections are required as there is no prescription in the bracket for torque correction (no 3rd-order modifications are possible). However, the present report evaluated indirect bonding for the 2D lingual system in order to reduce chair time of the bracket positioning appointment. Moreover, during direct bonding procedure on the lingual side of the tooth, often the clinician does not have a clear vision of the bonding area. Therefore, the advantage of a CAD/CAM indirect bonding is the possibility to zoom on details and provide a better position of the lingual bracket on the lingual surface. The implementation of a simplified lingual technique with CAD/CAM technology could offer orthodontic clinicians new interesting and feasible possibilities.
4. Conclusions
After an intraoral scan, a digital indirect bonding technique has been shown to be possible using the standard lingual brackets which is both repeatable and effective.
Disclosure
The authors point out that a preliminary report showing the part of the photographs of this manuscript has been presented in a session poster of the 49th International SIDO (Società Italiana di Ortodonzia) Congress, Florence, 2018, 11-13 October.
Conflicts of Interest
The authors declare that they have no conflict of interest.
ShpackN.GeronS.FlorisI.DavidovitchM.BroshT.VardimonA. D.Bracket placement in lingual vs labial systems and direct vs indirect bonding200777350951710.2319/0003-3219(2007)077[0509:BPILVL]2.0.CO;22-s2.0-34248212693HodgeT. M.DhopatkarA. A.RockW. P.SparyD. J.The Burton approach to indirect bonding200128426727010.1093/ortho/28.4.2672-s2.0-0035654183KotariA.Indirect bonding technique200674389393CarlsonS. K.JohnsonE.Bracket positioning and resets: five steps to align crowns and roots consistently20011191768010.1067/mod.2001.1112202-s2.0-0035220077HodgeT. M.DhopatkarA. A.RockW. P.SparyD. J.A randomized clinical trial comparing the accuracy of direct versus indirect bracket placement200431213213710.1179/1465312042250204272-s2.0-3042784116NicholsD. A.GardnerG.CarballeyraA. D.Reproducibility of bracket positioning in the indirect bonding technique2013144577077610.1016/j.ajodo.2013.04.0232-s2.0-84887108639KalangeJ. T.Indirect bonding: a comprehensive review of the advantages20045430130715633375MeniniA.CozzaniM.SfondriniM. F.ScribanteA.CozzaniP.GandiniP.A 15-month evaluation of bond failures of orthodontic brackets bonded with direct versus indirect bonding technique: a clinical trial20141517010.1186/s40510-014-0070-92-s2.0-84964695207KooB. C.ChungC. H.VanarsdallR. L.Comparison of the accuracy of bracket placement between direct and indirect bonding techniques1999116334635110.1016/S0889-5406(99)70248-92-s2.0-0033190794ÖzsoyÖ. P.PamukçuH.Lingual treatment of an adult patient with a simplified extraction protocol2018312626610.5152/TurkJOrthod.2018.1706130112516ScribanteA.SfondriniM. F.FraticelliD.MalfattoM.GandiniP.Adhesive systems for CAD-CAM customised lingual orthodontic brackets: which one is better?201718318819210.23804/ejpd.2017.18.03.042-s2.0-8503658528529254341BinhuwaishelL.Al-JewairT.Lingual fixed orthodontic appliances may be associated with more adverse effects than buccal appliances201818434935110.1016/j.jebdp.2018.10.0072-s2.0-85057544484ScribanteA.SfondriniM. F.CollesanoV.TovtG.BernardinelliL.GandiniP.Dental hygiene and orthodontics: effect of ultrasonic instrumentation on bonding efficacy of different lingual orthodontic brackets201720176371465110.1155/2017/37146512-s2.0-8502865628728904955SfondriniM. F.DebiaggiM.ZaraF.BrerraR.ComelliM.BianchiM.PolloneS. R.ScribanteA.Influence of lingual bracket position on microbial and periodontal parameters in vivo201220335736110.1590/S1678-775720120003000112-s2.0-84864689008KwonS. Y.KimY.AhnH. W.KimK. B.ChungK. R.Kim (Sunny)S. H.Computer-aided designing and manufacturing of lingual fixed orthodontic appliance using 2D/3D registration software and rapid prototyping20142014816416410.1155/2014/1641642-s2.0-8490179711624899895MayhewM. J.Computer-aided bracket placement for indirect bonding200539653CiuffoloF.EpifaniaE.DurantiG.de LucaV.RavigliaD.RezzaS.FestaF.Rapid prototyping: a new method of preparing trays for indirect bonding20061291757710.1016/j.ajodo.2005.10.0052-s2.0-31544480667TanakaO. M.FornazariI. A.ParraA. X. G.CastilhosB. B.FrancoA.Complete maxillary crossbite correction with a rapid palatal expansion in mixed dentition followed by a corrective orthodontic treatment20162016610.1155/2016/83063972-s2.0-84973345107830639727239351SfondriniM. F.GandiniP.CastroflorioT.GarinoF.MergatiL.D’AncaK.TrovatiF.ScribanteA.Buccolingual inclination control of upper central incisors of aligners: a comparison with conventional and self-ligating brackets201820187934182110.1155/2018/93418212-s2.0-8505880346930627583ShaikJ. A.GuramG.A comparative evaluation of canine retraction using ceramic bracket and ceramic bracket with metal slot with conventional preadjusted edgewise appliance bracket systems: a clinical study20188429630310.4103/jispcd.JISPCD_301_172-s2.0-8505054835230123760HillE. E.Eye safety practices in U.S. dental school restorative clinics, 2006200670121294129717170319ScribanteA.Contreras-BulnesR.MontasserM. A.VallittuP. K.Orthodontics: bracket materials, adhesives systems, and their bond strength201620163132981410.1155/2016/13298142-s2.0-8499420709727818996ScribanteA.SfondriniM. F.BrogginiS.D'AlloccoM.GandiniP.Efficacy of esthetic retainers: clinical comparison between multistranded wires and direct-bond glass fiber-reinforced composite splints20112011554835610.1155/2011/5483562-s2.0-8485516359022114597DemirA.BabacanH.NalcacıR.TopcuogluT.Comparison of retention characteristics of Essix and Hawley retainers201242525526210.4041/kjod.2012.42.5.2552-s2.0-84869026987SfondriniM. F.GandiniP.MalfattoM.Di CoratoF.TrovatiF.ScribanteA.Computerized casts for orthodontic purpose using powder-free intraoral scanners: accuracy, execution time, and patient feedback201820188410323210.1155/2018/41032322-s2.0-8504674156929850512BurhardtL.LivasC.KerdijkW.van der MeerW. J.RenY.Treatment comfort, time perception, and preference for conventional and digital impression techniques: a comparative study in young patients2016150226126710.1016/j.ajodo.2015.12.0272-s2.0-84994817312DewhurstR.Assessment of computer customized brackets and positioning jigs2012231535822533029KimH. M.BaekS. H.KimT. Y.ChoiJ. Y.Evaluation of three-dimensional position change of the condylar head after orthognathic surgery using computer-aided design/computer-aided manufacturing–made condyle positioning jig20142562002200710.1097/scs.0b013e3182a246f12-s2.0-85027918224JacobsC.KatzorkeM.WiechmannD.WehrbeinH.Schwestka-PollyR.Single tooth torque correction in the lower frontal area by a completely customized lingual appliance20171311810.1186/s13005-017-0152-22-s2.0-8503087005629017523TyneliusG. E.Orthodontic retention. Studies of retention capacity, cost-effectiveness and long-term stability201423623696526685634ZarauzC.ValverdeA.Martinez-RusF.HassanB.PradiesG.Clinical evaluation comparing the fit of all-ceramic crowns obtained from silicone and digital intraoral impressions201620479980610.1007/s00784-015-1590-52-s2.0-84941361665HiroT.TakemotoK.Resin core indirect bonding system-improvement of lingual orthodontic treatment1998578391TamizharasiK. S.KumarD. S.Evolution of orthodontic brackets201012535ScribanteA.SfondriniM. F.FraticelliD.DainaP.TamagnoneA.GandiniP.The influence of no-primer adhesives and anchor pylons bracket bases on shear bond strength of orthodontic brackets20132013631502310.1155/2013/3150232-s2.0-8488315995923984339SagerB.RosenD. W.ShillingM.KurfessT. R.Experimental studies in stereolithographic resolutionProceedings of the Solid Freeform Fabrication Symposium2003Austin, Tex, USA7081