![ A net force of 40g (base level
force of an aligner after 48
hours) intended to move the
tooth lingually would require a
moment of 320 to 400g/mm
(moment-to-force [M/F] ratio 8
to 10) for bodily movement or
greater than 400g/mm (force-
to-moment [F/M] ratio less than
10) for lingual root movement.
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CLEAR ALIGNERS Basic And Types Of Attachment
- 2. CONTENTS Introduction History Scanning and digitization Records, diagnosis and treatment planning for clear aligner treatment Clincheck—an overview Movement of tooth in aligner treatment Staging of tooth movement in clincheck Attachment design in the invisalign system Power ridges and pressure areas in the invisalign system Root control ,rotation correction, extrusion In the invisalign system Deep bite, ectopically positioned teeth , crossbites Auxiliaries and the invisalign system Invisalign teen Others 2
- 3. The very need for orthodontic treatment by a majority of adult patients is derived with a desire for enhancement of dental alignment and facial aesthetics. Although buccal fixed metallic appliances are efficient treatment systems, the reluctance of their use is mainly due to metal look, poor aesthetics and fear of pain. Clear plastic aligners offer an excellent alternative to unaesthetic orthodontic treatment with labial fixed appliances. INTRODUCTION 3
- 4. The concept on which treatment with clear aligners is based has been around since the 1940s. In 1945, H. D. Kesling suggested that a series of tooth positioners be used to produce the types of movements that are needed for orthodontic treatment. HISTORY 4
- 5. Nahoum described a method to change tooth contours using thermoformed plastic. In 1971, Pontiz introduced a thermoformed plastic appliance called the “invisible retainer” made on a master model that repositioned teeth with base-plate wax. 5
- 6. Sheridan and colleagues later developed a technique involving interproximal tooth reduction and progressive alignment using clear Essix appliances, and those techniques were further developed by Hilliard and Sheridan with a series of special thermoforming pliers designed to enhance specific movements. 6
- 7. In 1998, Align Technology, Inc. introduced Invisalign to the orthodontic market. It used computerized 3D technology to visualize and move the teeth in a virtual model. 7
- 8. Clear aligners can be categorized into four basic categories. First category are commonly known as positioners or guide. This category includes the original Allesee Orthodontic Appliances (AOA) positioner described by Kesling. Product Name Orthodontics Positioner Nite-Guide; Occlus-o- Guide;Preformed positioner Myobrace i-3, i-2, Myobrace 8
- 9. The second category consists of those thermoformed appliances, sometimes known as Essix Retainers and removable appliances referred to as spring aligners. The Essix appliance can be fabricated in the orthodontist’s office or sent to a commercial laboratory, and it uses the techniques of Sheridan and Hilliard Aligners Currently Available: Activation Aligners and Appliances MTM Clear Aligner Straight ‘N’ Clear Cosmetic Correctors Inman Aligner Clear Aligner 9
- 10. The third category consist of aligners that are fabricated from models that have had teeth cut out and manually moved to the correct position. If done in a series of models, an aligner can be fabricated from each model. These appliances can be used for minor movement of upper and lower anterior teeth and usually consist of three to five aligners. Aligners Currently Available: Teeth Manually Reset Clear Image Aligners Red White Blue Simpli Originator Clear Aligner System Dual Laminate 10
- 11. The last category, aligners fabricated from digitally manipulated models, is the largest growing area in aligner treatment. Using digital technology to control tooth movement, intricate and precise tooth movements can be staged for each sequential aligner. 11
- 12. Invisalign treatment has a terminology that differs from traditional fixed appliances. A midcourse correction involves a temporary pause in treatment while a new scan is taken or impressions are made; treatment is then continued once new aligners are fabricated. 12
- 13. Another term unique to aligner treatment is refinement. Refinement is similar to midcourse correction in that it generally involves pausing treatment and taking new impressions and ordering a new series of aligners. The only difference is that refinement takes place near the end of treatment when one or more teeth are apparently not positioned exactly as desired. The final term unique to aligner treatment is attachment. Attachments are small composite additions to the tooth surface that enhance areas of undercut either for retention or to facilitate specific movements. 13
- 14. An instant virtual model from an intraoral scanner, in combination with multiple software platforms, now allows the orthodontist to manipulate teeth with or without the assistance of a technician. That, along with a three-dimensional printer, allows the orthodontist to make aligners easily in his or her office once the cost of the three components (scanner, software, and three dimensional printer) becomes more affordable. SCANNING AND DIGITIZATION 14
- 15. Every current scanner has a hand-held wand containing a camera that is connected to a computer for data collection and manipulation. The wand may project either laser or white light onto the tooth surface where it is reflected back to the camera, after which hundreds of thousands of measurements per inch are performed to recreate the three-dimensional representation of the teeth. The technology engineered into the wand, which captures the surface data, determines the measurement speed, resolution, and accuracy of the scanner. 15
- 16. Four types of imaging technologies are currently used Triangulation Parallel confocal imaging Accordion fringe interferometr y Three- dimensional in-motion video 16
- 17. CEREC (Chairside Economical Restoration of Esthetic Ceramics or CEramic REConstruction) was the first in-office intraoral scanner introduced to dentistry in the early 1980s.CEREC works using triangulation. This technique measures the angles and distances from known points (laser source and sensor) with projected laser light. The CEREC system determines the angle of reflection and the distance from the laser source to the object’s surface as light reflects off the object. TRIANGULATION 17
- 18. Parallel confocal imaging projects laser light through a pinhole to the target. The sensor is placed at the imaging plane where it is in focus (confocal). A small opening in front of the sensor blocks any light from above or below. Only the focused light reflecting off the target tissue will reach the sensor for processing. This type of system creates thousands of tomographic slices and stitches them together to form the three-dimensional picture. PARALLEL CONFOCAL IMAGING 18
- 19. Two sources of light are used with accordion fringe interferometry (AFI) to project three patterns of light, called “fringe patterns,” onto the teeth and tissue. Based on the shape of the object, the fringe pattern distorts and takes on a new pattern. Surface data points of the fringe curvature are recorded by a high-definition video camera that is offset from the projector by approximately 30 degrees. ACCORDION FRINGE INTERFEROMETRY 19
- 20. Three-dimensional, in-motion video uses three tiny high-definition video cameras at the lens to capture three precise views of the target. A sensor behind the cameras converts the light energy into electrical signals, which allows the distances between two data points to be calculated simultaneously from two perspectives to create the three- dimensional data. The data points are captured in a video sequence and modeled in real time. THREE-DIMENSIONAL IN-MOTION VIDEO 20
- 21. The second part of the process is integrating the software that provides the ability for the technician or orthodontist to manipulate teeth in preparation for manufacturing aligners. If the aligners are manufactured by a vendor, then the orthodontist simply orders them once the setup is complete, and the rest is taken care of by the vendor of his or her choice. 21
- 22. If the orthodontist should decide that he or she wants to manufacture his or her own aligners, then a three-dimensional printer is required to produce the models on which the aligners will be formed. 22
- 23. Three-dimensional printers Stereolithography Fused deposit modeling (FDM) Digital light processing (DLP) Poly-Jet photopolymerization (PPP) printers 23
- 24. 24
- 25. Four-dimensional printing involves using three-dimensional printing and special geometric properties along with material characteristics to print objects that can change their configuration based on outside influences, such as motion or pressure. 25
- 26. Orthodontic records routinely include study casts, intraoral and extraoral photographs, and panoramic and lateral cephalometric radiographs. Additional diagnostic records may include a three-dimensional (3D) cone beam computed tomography (CBCT) scan, periapical radiographs, posteroanterior cephalometric radiographs and any other diagnostic records as deemed necessary to the case. RECORDS, DIAGNOSIS AND TREATMENT PLANNING FOR CLEAR ALIGNER TREATMENT 26
- 27. Clear aligner therapy provides a specifically controlled force system that primarily affects the maxillary and mandibular dentition in all three planes of space. Growing patients wearing aligners have the potential to have a small effect on the maxilla and the mandible, whereas in adults, the effect will be negligible. 27
- 28. 28
- 29. First, the determination should be made that clear aligner treatment is the appropriate force system, based on the treatment goals derived from the prioritized treatment objectives. More to the point, clear aligners are tooth-moving appliances that have very minimal impact on skeletal structures. Therefore clear aligners would not be the appropriate force system for transverse skeletal problems or for severe sagittal problems attributable to poorly aligned skeletal structures. 29
- 30. Clear aligners are well suited and appropriate when the treatment goals can be achieved by tooth movement in all three planes of space. Examples are numerous and include all sagittal Angle molar classifications, with mild to moderate corrections in the transverse and vertical planes. 30
- 31. The virtual setup for Invisalign-branded clear aligner treatment is viewed by the orthodontist in a software program called ClinCheck. The goal of the virtual setup, when modified and completed by the orthodontist, is to make the individual tooth movements shown in the ClinCheck depict the actual individual tooth movements required to correct the malocclusion. CLINCHECK—AN OVERVIEW 31
- 32. The technician’s responsibility is to provide a virtual set-up that Follows the instructions on the prescription form and Delivers tooth movements that fall within the predetermined defaults of Invisalign’s Treat software. 32
- 33. The technician uses a very robust proprietary software called Treat, and the orthodontist’s interface with that program is a scaled-down version called ClinCheck. Once the orthodontist has completed the virtual setup, the true power of the Treat program is exhibited by the application of SmartForce enhancements. 33
- 34. SmartForce features are patented engineered solutions designed to create precise biomechanical forces on selected teeth or groups of teeth. Research and development of the SmartForce features, combined with the proprietary plastic, are unique to Invisalign. 34
- 35. ClinCheck Pro, with its ability to control tooth and arch movement, is a paradigm shift in the way orthodontists now achieve the desired virtual setup. With the introduction of ClinCheck Pro (v3.1) and subsequent updates in ClinCheck Pro (v4.1), the value of tooth movement measured to within hundredths of a millimeter are displayed on the bottom of the screen . Orthodontists can now couple the proposed tooth movements in their treatment plans to the virtual setup and verify that all tooth movements are accurate in all three planes of space. 35
- 36. 36
- 37. MOVEMENT OF TOOTH IN ALIGNER TREATMENT 37
- 38. When an archwire is engaged onto a lingually erupted tooth, the elasticity in the archwire causes the archwire to return to its original arch form. As the archwire returns to its original shape, it pulls on the lingually erupted tooth to move it into the arch In contrast, clear aligners move teeth by exerting a push force. The aligner deforms over the teeth, and the elasticity in the aligner material pushes the teeth into position. 38
- 39. Clear aligners engage teeth by having aligner material wrapped around teeth. The more aligner material wrapped around a tooth, the better the engagement. For effective tooth movement to take place, even in simple situations, aligners must be worn 22 hours a day, essentially the same as for fixed appliances. In teeth with long clinical crowns and larger surface area, there is better engagement and therefore better expression of tooth movement. 39
- 40. An important aspect of controlling tooth movement with aligners is staging. Staging is the sequence in which and the speed at which teeth are moved with aligners. STAGING OF TOOTH MOVEMENT IN CLINCHECK 40
- 41. As in the collision table, the numbers across the top represent different teeth, and the vertical axis represents an aligner number. The vertical black bars in the diagram indicate the timing and rate of tooth movement. Each aligner number then represents one stage. 41
- 42. An alternative to segmented staging that more closely mimics fixed appliance treatment is simultaneous staging. This standard simultaneous staging pattern is also referred to as X staging pattern. The basis for simultaneous movement is that all of the teeth within each arch are moved together from the initial stage through the final stage. 42
- 43. Distalization of the maxillary dentition, starting with the molars, followed by the bicuspids, and ending with the retraction of the anterior teeth, is a type of staging known as V staging pattern and typically applies only to the upper arch. The opposite of V staging pattern, in which the anterior teeth move anteriorly, followed by posterior teeth moving anteriorly, is known as A staging pattern. 43
- 44. This pattern could be used in either arch to open previously closed extraction spaces or to attempt to mesialize an entire arch in a segmental fashion. M staging pattern is solely used for bicuspid extraction treatment. In this staging pattern, movement starts by first closing the extraction spaces, followed by the alignment of anterior teeth, and finishing with molar movement. 44
- 45. This three-dimensional simulation attempts to mimic maximum anchorage of the molars by showing no movement as the remainder of the arch changes. 45
- 46. Attachments can be used for the retention of the aligner, as well as to enhance or facilitate specific tooth movements. Optimized attachments allow the proprietary aligner material (SmartTrack) to produce the required force, which creates the moment required to move the tooth as shown in the ClinCheck. ATTACHMENT DESIGN IN THE INVISALIGN SYSTEM 46
- 47. Some optimized attachments will have excess space opposite the active surface to allow the tooth to move unimpeded in the correct direction. Although, clinically, this may give the appearance that the attachment is not fully seated in the aligner, this excess space is intentional by design. Manually placed or physician-prescribed attachments, are those which are placed by the orthodontist when modifying a virtual treatment plan. 47
- 48. The first of the manually placed attachments was the ellipsoid attachment. The beveled attachment was developed by rotating a portion of the rectangular attachment virtually into the tooth surface. The orthodontist can now make one rectangular attachment be any type of rectangular attachment he or she prefers —horizontal or vertical, bevel incisal or gingival. 48
- 49. 49 Rectangular attachments Beveled attachment Vertical rectangular attachments- Vertical rectangular attachments are useful for root control. If there is significant root tip to correct root inclinations on the mandibular incisors, then a vertical rectangular attachment should be placed. Horizontal rectangular attachments-Horizontal rectangular attachments may also be used for root control, particularly in the buccolingual dimension to effect buccal root torque on molars. They may also be used where a short clinical crown or occlusal interference does not allow placement of a vertical rectangular attachment Both the vertical and horizontal attachments may also be beveled. The bevel provides a flat surface for the aligner to push against to effect the desired tooth movement. For extrusive tooth movements on posterior molars, a horizontal attachment that is beveled on the gingival will be effective. For intrusion, use a horizontal attachment beveled on the occlusal.
- 50. A net force of 40g (base level force of an aligner after 48 hours) intended to move the tooth lingually would require a moment of 320 to 400g/mm (moment-to-force [M/F] ratio 8 to 10) for bodily movement or greater than 400g/mm (force- to-moment [F/M] ratio less than 10) for lingual root movement. 50
- 51. Improper attachment design or placement allows the delivery of only 280g/mm moment in conjunction with 40g force, resulting in controlled lingual crown tipping. Although the forces may be in opposite directions, the aligner provides the same level of force on both sides of the teeth. 51
- 52. An alternative to attachments that help facilitate torque control is the SmartForce feature known as a power ridge Power ridges are engineered corrugations placed at specific locations to enhance the undercut near the labial gingival margin of teeth undergoing torquing movements. POWER RIDGES AND PRESSURE AREAS IN THE INVISALIGN SYSTEM 52
- 53. The power ridges function in two ways: To stiffen the gingival third of the aligner to make it more resilient To provide additional force as close to the gingival margin as possible to increase the effective moment arm of the aligner. The obvious advantage to power ridges is that attachments need not be placed or removed, and they are more aesthetically acceptable to the patient. 53
- 54. Another aspect of biomechanics, especially pertinent to extraction treatment, is to control tipping to achieve root parallelism. When a force is applied in an attempt to move a canine distally, the tooth will rotate around the center of resistance. A sufficient moment is required to oppose the tipping movement. ROOT CONTROL IN THE INVISALIGN SYSTEM 54
- 55. In clear aligner therapy, this issue may be overcome by requesting root control attachments on teeth adjacent to the extraction site. Unfortunately, canines often remain upright during retraction into premolar spaces, whereas the clinical crowns of molars, especially maxillary molars, tend to tip mesially, which is frequently referred to as “dumping”. 55
- 56. G6, the latest release of SmartForce features, has antitipping attachments and pressure areas built into the molars to limit dumping of the clinical crowns in extraction cases. TADS can also be used as anchorage to avoid placing forces on teeth that could cause unnecessary tipping. 56
- 57. Before the addition of SmartForce attachments, many of which are specifically designed to correct rotated teeth, using auxiliaries before, during, or after aligner treatment was needed to accomplish the rotational correction. Optimized attachments are now available for all bicuspids and cuspids. The default for the bicuspids and cuspids is rotation correction greater than 5 degrees in either direction. ROTATION CORRECTION IN THE INVISALIGN SYSTEM 57
- 58. Align Technology subsequently released an engineered solution to assist extrusion of maxillary and mandibular incisors and cuspids. The default that causes the attachment to be added to the virtual plan is extrusion of more than 0.50 mm down the long axis of the tooth. An additional SmartForce feature improves the tracking of anterior teeth extrusion when all four upper incisors are individually extruding more than 0.50 mm. EXTRUSION CORRECTION IN THE INVISALIGN SYSTEM 58
- 59. This pressure area produces a higher force on the optimized attachment to keep the teeth fully engaged in the aligner. Even with extrusion of anterior teeth, an advantage of using aligners for treatment is the posterior intrusive affect that the aligners will have on the posterior teeth which also facilitates closure of the anterior openbite. 59
- 60. In particularly challenging situations, a button bonded to the tooth, together with an elastic, will assist with the extrusion and it can be a very useful technique to finish treatment when only minor extrusion of a single tooth is required. 60
- 61. Deepbites are generally treated by anterior intrusion which can be difficult with aligners. Invisalign uses attachments on the premolars for anchorage while an active intrusive force is placed on the incisors as well as bite ramps built into the lingual of the aligner of the upper anterior teeth that act as a bite plane. DEEPBITE 61
- 62. Another difficult type of tooth movement to achieve with this appliance initially was in the movement of severely, ectopically positioned teeth. The use of more flexible materials and extension of material further gingivally was necessary to complete this type of treatment. ECTOPICALLY POSITIONED TEETH 62
- 63. Minor anterior or posterior crossbites with a bite depth up to about 10% are usually not difficult to treat with just the usual aligner treatment. Anterior or posterior crossbites with a bite depth greater than approximately 10% usually requires some other considerations to open the vertical to allow the tooth in crossbite to clear the opposing teeth such as anterior bite ramps that are available on the Invisalign aligners or placing cold-cure acrylic on the occlusal surface of the aligners while the crossbite is being jumped. CROSSBITES 63
- 64. In order to avoid occlusal trauma to the teeth as the crossbite is correcting, the aligners may need to be worn full-time including while eating until the crossbite is jumped. 64
- 65. Other auxiliaries can be used to facilitate specific movements. Class II and Class III elastics are frequently needed. One can directly attach the elastics either to the aligner or to the buttons bonded to the teeth. If the elastics are directly attached to the aligner, then attachments are generally required to prevent displacement of the aligner. AUXILIARIES AND THE INVISALIGN SYSTEM 65
- 66. Miniscrews can also be effectively used with aligners. The two most common uses of miniscrews with aligners are for vertical and sagittal movements. One such example is the extrusion of an upper canine. Another vertical movement that is easily enhanced with miniscrews is the intrusion of molars that have supererupted into an edentulous space. 66
- 67. A miniscrew in the lower arch and then running a rubber band from a clear button near the gingival on the upper canine to the miniscrew as the aligner guides the tooth into the correct position. 67
- 68. Another application of miniscrews with aligners is correcting an arch asymmetry by enhancing the distalization of one side. This correction can be accomplished by placing a miniscrew in the retromolar area, bonding buttons on the facial and lingual aspects of the upper first or second molar, and then connecting an elastic chain from the buttons to the miniscrew. 68
- 69. Originally, Invisalign was anticipated for use with adults for those individuals with a fully erupted permanent dentition. It soon became apparent, however, that being able to treat the late mixed dentition with aligners provided certain benefits as well. INVISALIGN TEEN 69
- 70. The shortcomings to overcome were anticipating tooth eruption of one or more permanent teeth, being able to monitor patient compliance to discuss the progress (or lack thereof) with parents, proper control of torque without the need for attachments when crowns were not yet fully exposed, and, finally, avoiding practice management issues over lost aligners. Eruption tabs are used to prevent supereruption of unerupted second molars. 70
- 71. Wear indicators are placed on the facial surfaces of the first molars . Two different types of chemical indicators are available that turn from dark blue to clear as the aligners are worn. These indicators are designed so that creative teenagers cannot realistically figure out a method to have both indicators change without actually wearing the aligners. 71
- 72. The clear smile system- Clear Smile corrector system is predominantly suitable for mild malocclusions. As a general rule, any non-extraction treatment case that could be treated with fixed appliance without inter-arch mechanics is likely to be suitable. ClearPath- ClearPath is a USFDA approved technology that fabricates series of clear wafer-thin transparent plastic removable aligners that gently guide the teeth from their present to the desired position. OTHERS 72
- 73. The system aims to address most dental malocclusions, ranging from crowding, spacing, cross-bites, open bites, deep bites, proclinations and rotations. ClearPath has made several advancements over classic aligner systems almost eliminating the use of attachments, buttons, engagers and elastics. 73
- 74. This system, however, is not indicated for any mixed dentition or skeletal cases and does not aim to correct complex malocclusions in the anterior– posteriors relationship. It is used in mild to moderate cases. ClearPath aligner does not cover gingiva at all and finishes just short at the gingival margin, enhancing the comfort of the aligner trays. 74
- 75. Orthodontics current principles and techniques- Graber vanarsdall Timothy T. Wheeler, Orthodontic clear aligner treatment, Seminars in Orthodontics 2016. Boyd RL, Vlaskalic V. Three-Dimensional Diagnosis and Orthodontic Treatment of Complex Maloccluslons With the Invlsalign Appliance. Semin Orthod. 2001;7:274-283. Clear aligner technique Wong BH. Invisalign A to Z. Am J Orthod Dentofacial Orthop 2002;121:540-1 Orthodontics: diagnosis and management of malocclusion and dentofacial deformities- OP Kharbanda Kesling HD. The philosophy of the tooth positioning appliance. Am J Orthod 1945;31:297-304. REFERNCES 75
- 76. THANK YOU 76
Editor's Notes
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