Aligners

A Complete Oveview on Aligners in Orthodontics.

1. A ligner s Presented By: Dr. Anil Kumar Godara 1

2. C o n t ents Introduction Advantages H istory of clear aligner treatment Fabrication of clear aligner what is Clin check software ? Smart Force features and Attachments 2

3. Biomechanics Clear Collection instruments for clear aligner treatments A Clinical Case Treated with Clear Aligners Accelerated Extraction Treatment with Invisalign Periodontal considerations Conclusion References 3

4. I n t r o d u c t i o n Aligners are an alternative to traditional braces and are designed to help guide teeth into their proper position. Similar to braces, aligners use a gradual force to control tooth movement, but without metal wires or brackets. The aligners are made of a strong plastic material and are fabricated to fit each person's mouth. If a series of aligners are made, each aligner moves the teeth a little bit more into place until the desired movement is completed . Aligners are worn for at least 20 hours a day to reach the desired maximum effectiveness . 4

5. Each aligner is worn for two to three weeks before changing to the next one. The length of treatment with aligners depends upon the severity of each case. Typically, aligner treatment can be as short as three weeks or as long as six months. Still , a much shorter treatment than traditional braces . Each aligner is designed to move the teeth a maximum of about 0.25 to 0.3 mm over a 2-week period, and is worn in a specific sequence. The Invisalign appliance is currently recommended for adults and for adolescents with fully erupted permanent teeth who meet an acceptable standard of compliance. 5

6. Excellent compliance is mandatory since the appliance has to be worn a minimum of 20 to 22 hours a day and each aligner should be worn 400 hours to be effective . Scheau et al proposed the first thermoforming machine to synthesize orthodontic appliances in 1966. Currently 2 types of thermoforming machines ,The Ministar and Biostar ( scheau Dental) 6

7. Advantages A ligners are removable so it is easier to brush and floss after meals. A ligners are easier to keep clean. A ligners are comfortable and less likely to irritate gums and cheeks. A ligners can prevent tooth wear from grinding. 7

8. H istory of clear aligner treatment Clear aligner treatment falls into ESSIX RETAINER INVISALIGN 8

9. The first category consists of thermoformed appliances sometimes known as ESSIX RETAINERS . This are fabricated by making adjustments to the tooth positions on plaster or stone models and fabricating one or more aligners to correct a minor malocclusion. The second category is Invisalign is a proprietary orthodontic technique that uses a series of computer generated custom plastic aligners to gradually guide the teeth into proper alignment. It is both a brand name and a technique and is used synonymously . Invisalign is the computer aided design and manufacturing (CAD – CAM) Precision aligner product. The company and the technique was the brainchild of two graduate business student at Stanford university – 1997,Kelsey Wirth and Zia Chishti . 9

10. Fabrication of clear Aligners Clear aligners are virtually invisible, made from thermoplastic material developed in such a fashion to achieve desired results. They are custom- made trays, worn in a sequential manner to successfully achieve treatment outcome. 10 There are a few steps to fabricate Clinical steps Impressions Images X- rays. Laboratory steps Scans 3D models Aligners Quality check

11. PVS impressions (Polyvinyl siloxane ) with a light body for the margin as aligners are custom -made – as aligner snuggly fits the tooth surface to apply active forces for tooth movement. Other substitutes for impressions are intraoral scans. Dental impressions are scanned in order to create a digital 3D representation of the teeth Technicians move the teeth to the desired location with the program Treat, which creates the stages between the current and desired teeth positions . Anywhere from six to forty-eight aligners may be needed. Each aligner moves teeth .25 to .33 millimeters. IMPRESSIONS 11

12. IMAGES It is very important to help to plan and understand the treatment plan. It is important to record both extra-oral and intraoral images of the patient. The orthodontic treatment is a comprehensive treatment plan not only skeletal and dental but also, soft tissue. Your lips, nose, chin and other facial structures contribute while planning treatment. 12

13. X -RAYS An important tool to help determine the number of teeth, there roots positioning and more. 13

14. CLEAR ALIGNERS LABORATORY PROCEDURE I t is simple yet very precise and planned step. The impressions/ scans are prepared to achieve a replica of your teeth. Once the scans are ready. The three – dimensional models are prepared. Virtual set up is prepared to show the planned treatment result in the end. This gives an edge to  clear aligner  therapy compared to traditional orthodontic treatment. The models are checked, and your trays are prepared. 14

15. A computer graphic representation of the projected teeth movements, created in the software program ClinCheck , is provided to the doctor for approval or modification before aligners are manufactured .   The aligners are modeled using CAD-CAM (computer-aided-design and computer-aided-manufacturing) software and manufactured using a  rapid prototyping  technique called  stereolithography . The molds for the aligners are built in layers using a photo-sensitive liquid resin that cures into a hard plastic when exposed to a laser .   The aligners are made from an elastic  thermoplastic  material that applies pressure to the teeth to move into the aligner's position . 15

16. 3-D MODELS 3D models are prepared using 3d printing which is built in layers using a light-sensitive liquified resin which solidifies when exposed to the laser. The models are prepared then the thermoplastic trays are compressed to achieve the desired shape, snuggly fitting the model. These trays are called aligners which move teeth to the desired position. 16

17. Gingival Contouring 17

18. Clin Check The software used by the orthodontist in the office is called clin check. It allows the orthodontist to view the treatment in all the aspects as well as superimpose one stage of treatment over another to visualize individual tooth movements so as to gauge the probability of accomplishing the desired movement that will be biologically feasible. 18

19. Attachments The New Attachment Protocol allows for attachments to be passive or active. Passive attachments are for aligner retention and anchorage for intrusion . Active attachments are used for rotations of rounded teeth, extrusion and root correction. Currently , Align Technology has three types of attachments for commercial use: the ellipsoid, rectangular and the beveled attachment. 19

20. Ellipsoid attachments are often placed horizontally and are the default for anterior tooth extrusions. They are 1mm in thickness and placed between the cervical and middle third of the tooth. 20

21. Vertical rectangular attachments as seen in are the default for rotations of canines and premolars. In addition, these attachments are used for root control on teeth adjacent to extraction spaces. For premolar extraction cases, the default is placement of two rectangular attachments distal to the space and one mesial to the extraction space. Typically these attachments are 1mm thick, 2mm wide and either 3, 4 or 5 mm long. 21

22. The vertical rectangular attachments are very retentive, so care should be taken when placing multiple attachments in one quadrant. The aligner can become too retentive for patient convenience. An interesting option is the beveled attachment for rotations. Sometimes the rectangular attachments don’t fit perfectly and during rotation can put unintended forces on the tooth, resulting in side effects. Beveling the attachment can ease the fit and make the attachment “active,” causing rotation. 22

23. SmartForce Features are: Engineered to deliver the force systems necessary to achieve more predictable tooth movements. Customised to each tooth using advanced virtual modeling, including such features as the width, long axis, and contour of the entire tooth. Positioned more precisely to deliver the necessary forces while eliminating interferences and automatically placed in accordance to the desired movement. Smart Force features and Attachments. 23

24. Biomechanics The use of aligners is far more complicated than most people believe . It takes a knowledgeable clinician with considerable experience to use the appliance to its maximum. In order to determine just what that maximum height be with invisalign in its current rendition of aligner materials , we must examine the biomechanics of tooth movement with invisalign. 24

25. Aligner Bio-Mechanics! By: Dr. Willy Dayan Willy Dayan’s Golden Rules of Invisalign Bio-Mechanics 1) Think Like Plastic and Feel Like a Tooth: Invisalign is a removable appliances and thus cannot glue to teeth in order to “pull” them; the aligner can only “push” on surfaces of the teeth or surfaces of attachments. When a force is placed upon at tooth, it will move according to biomechanical principles that exist, no matter what the computer screen shows. 2) The Clincheck Video is not T eeth Moving: Stop watching the Clincheck movements as “moving teeth”! Think of the images as representing the anatomy of the “changing inner aligner surfaces”, and then analyze the resulting forces the aligner will exert upon the teeth. 25

26. Controlling Torque A net force of 40 gm (base level force of an aligner after 48hrs) intended to move the teeth lingually would require the moment of 320 to 400g-mm (M/F ratio- 8/10) for bodily movement or greater than 400g - mm for lingual root movement. Improper attachment design or placement allows the delivery of only 280g-mm moment in conjuction with 40g force resulting in un controlled lingual crown tipping . It must be kept in mind that the aligner provides the same level of force on both sides of the teeth, even though the forces may be in opposite direction . 26

27. This means that in the absence of spaces to close, Just as with fixed appliances, There must be some outside force system such as interarch elastics to provide a net distalizing force on the maxillary anterior teeth to produce lingual root movement. There is an inherent problem with rectangular attachments, because it is difficult for the patient to insert and remove the aligners. If the attachment and the aligner are not completely coupled then the result is an unwanted force system and unpredictable tooth movement. 27

28. 28

29. In order to facilitate greater ease of insertion and removal as well as eliminate the all or none situation the beveled attachment was developed by rotating a portion of the rectangular attachment virtually into tooth surface. 29

30. The beveled attachment can be utilized in multiple orientations simply by having the technician rotate the attachment in a different manner. There are theories that rotating the bevel in a specific directions will enhance specific movements. An alternative to the attachments that help facilitate torque control is the power ridges. These are engineered corrugations placed at specific locations to enhance the undercut near the gingival margin of teeth undergoing torqueing movements. 30

31. The ridge function in two ways . The first is to stiffen the gingival third of the aligner to make it more resilient . The other is 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 attachment need not be placed or removed and they are more esthetically acceptable to the patient. 31

32. Root parallelism Another aspect of biomechanics especially pertinent to extraction treatment is to control tipping in order to achieve root parallelism. An idea dating back to the late 1800s was to place an attachment on the gingival aspect of a bracket extending toward the center of resistance in an attempt to decrease the amount of tipping when teeth are moved mesiodistally. These gingival extensions are often described as power arms, they are added to the force system with invisalign in an attempt to alter the force- moment system. 32

33. It accomplishes two things, first it moves the application of force closer to the center of resistance, second it creates a secondary moment due to presence against the distal of the aligner. Unfortunately, often canines remain upright during retraction into premolar spaces, while the molars especially maxillary molars tend to tip mesially. This is frequently referred to as dumping. It also occurs when the molars are simply being used as anchorage for anterior retraction. This is probably caused by the undesirable crown to root ratio combined with the large root surface area over which the forces are distributed. 33

34. Work is currently being done with various attachment designs, to demonstrate the ability to predictably avoid molar dumping by placing attachments on the upper first or second molar as shown in the fig 34

35. Rotations Correcting rotations with aligner can be problematic. There are primary reasons for this. F irst is that aligners produce tooth movement by the plastic being slightly distorted and then elastically rebounding back to the predetermined shape and carrying the tooth with it . Even with the properly designed attachment ,another problem with rotations is that the tooth root is not a cylinder, and because of dilacerations and root surface variations, there is no way the computer software can adequately estimate the true rotational long axis. 35

36. For this reason we need to use auxiliaries either before ,during or after aligner treatment in order to accomplish the rotational correction. 36

37. Extrusions Extrusion can also present problems with the aligners. The reasons for this is similar to that of rotations . One method being used to overcome this problem with some promising results is to use the gingivally beveled attachment to provide a longer surface that can be elastically deformed and provide an extrusive force on the tooth. 37

38. 38

39. Other auxiliaries can be used to facilitate specific movements. Class II and class III elastics are frequently needed just as they are with fixed appliances . One can either attach the elastics directly to the aligner or attach elastics to buttons bonded to the teeth. 39

40. Keep in mind that if the elastics are directly attached to the aligner, then attachments are generally required to prevent displacement of the aligner. Toe nail clippers can be used to cut slits in the aligners for elastic placement. They have the advantage of producing a slit that is both contoured to the papillary embrasure form and that has a blunt apex to the slit does not tend to propagate and split the aligne r. 40

41. Mini screws can also be used effectively with the aligners in the same manners as they can with fixed appliances, either planned initially as part of the treatment or to help with movements that are not progressing as desired. highly placed canine 41

42. Another vertical movement that is easily enhanced with mini screws is the intrusion of molars that have supra erupted into an edentulous space. 42

43. Clear Collection instruments for clear aligner treatments The Tear Drop pliers is an instrument created for the purpose of adding a notch or hook at the gingival margin of clear aligners . A standardized notch is easily cut in a single step, creating a teardrop-shaped “reservoir” to hold the elastic on the tray , thereby making it easier for the patients to seat their aligner and connect their elastics. 43

44. Hu-Friedy’s Clear Collection of instruments designed to enhance clear aligner treatment 44

45. Teardrop-shaped hooks retain elastics when aligners are seated, making the addition of “rubber bands” easier for patients to manipulate. Notches are made at an angle to resist forces applied by the elastics 45

46. The Hole Punch The Hole Punch is used to cut a half-moon shaped hole at the gingival margin of aligners. These half-circle cuts permit the addition of bonded buttons, bonded orthodontic tubes or brackets with associated hooks, or are simply used to relieve impingement of plastic on soft tissue. 46

47. 47

48. The Hole Punch pliers can be used to relieve plastic impingement of gingival tissues anywhere along the aligners (e.g., incisive papilla irritation 48

49. Bootstrap mechanics If certain teeth are not “tracking” or are lagging behind (i.e., not fitting into the tray; Aligner Chewie are employed (Chewies™ Aligner Tray Seaters, Dentsply Raintree Essix, York, Pennsylvania). Patients are asked to hold the Chewie between the teeth in question and squeeze 10-15 seconds, release, and repeat for 5 minutes, 2-3 times per day. Aligner “lag” or lost tracking is most often characterized as an “air gap” between the incisal or occlusal of teeth and the plastic, indicating teeth are not following the prescribed tooth movement 49

50. Aligner Chewies are held tightly been specific “lagging” teeth for 10-15 seconds. This process is repeated for 5 minutes, 2-3 times daily, especially when changing to a new pair of aligner trays 50

51. Bootstrap mechanics to forcibly erupt a “lagging ” tooth using orthodontic elastics . The Hole Punch is employed to clear aligner plastic to permit the addition of bonded buttons. The Tear Drop is used to cut notches in mesial and distal embrasures 51

52. The Vertical pliers are used to accent rotational tooth movement. 52

53. ` The shallow indentations are produced without heating the pliers, producing “contact points” to assist with rotational couples , including situations with composite “attachments ”, enhancing molar distalization , or root paralleling and applying to the contact points immediately adjacent to composite attachments that increase sharps of the contact between plastic and composite attachment to avoid lose of tracking. . 53

54. In addition, the Horizontal is used to reduce “lag” by accenting extrusive or intrusive movement by applying contact points immediately adjacent to composite . 54

55. A Clinical Case Treated with Clear Aligners Clinical Case A 26-year-old female presented with a Class I malocclusion and an orthognathic profile. She was in the permanent dentition with retroclined maxillary central incisors, moderate overbite, spacing distal to the maxillary canines and mild crowding in the mandibular arch . Her primary concern was the alignment of her maxillary incisors and she refused to have fixed appliances. The treatment objectives using Invisalign were to align her front teeth, close space in the maxillary arch and alleviate crowding in the mandibular arch 55

56. 56

57. Invisalign treatment involved 24 upper and 10 lower aligners. Attachments were placed on several teeth to achieve a more predictable tooth movement using aligners. The patient wanted to reduce treatment time as much as possible and was instructed to change the aligners every 10 days instead of 14 days. After 8 months of initial treatment, a Case Refinement with 7 more aligners was needed to finish the maxillary arch. Once treatment was completed, a bonded lingual fixed retainer was placed on the maxillary incisors to prevent relapse 57

58. 58

59. The aligners have demonstrated excellent results in anterior alignment and good improvement in occlusion, transverse relationships and overbite correction. It is also possible to notice a reasonable improvement in midline position and overjet . Invisalign can be quite effective in correcting deep bites and mild crossbites by facilitating anterior intrusion while disocluding the posterior teeth. Patients with bruxism are good candidates for this treatment, as the aligners prevent occlusal wear and reduce pain in facial muscles and joints. Patients with extensive restorations and/or prostheses can benefit as well, as bonding orthodontic accessories can be more difficult . 59

60. Pre - treatment Post - treatment 60

61. Accelerated Extraction Treatment with Invisalign This 26-year-old female expressed a desire to correct her maxillary anterior crowding and improve the esthetic appearance of her smile. The patient’s facial profile was straight, but both lips were slightly recessive with regard to the E-line. Intraoral examination showed a Class II molar relationship with a 3mm overjet , a 1mm overbite, and coincident midlines. The arch length discrepancy was 13mm in the maxilla and 10mm in the mandible. They noted infra labioversion of both upper canines . 61

62. 62

63. 63

64. 64

65. 65

66. 66

67. 67

68. 68

69. 69

70. 70

71. Aligners are not only esthetically pleasing to adult patients but , because they are easily removed, extremely safe. In the future , aligners are likely be used in even more complex cases involving rotations, deep overbites, open bites, and unusual extractions. Further clinical investigations are needed into the effects of accelerated tooth movement in such cases. 71

72. Periodontal considerations There is a body of evidence growing that orthodontic treatment with aligners has less detrimental periodontal impact than that of fixed appliances. Miethke and Vogt and Miethke and Brauner compared the periodontal health of the patients who underwent the treatment with aligners to that of patients who underwent treatment with both labial and lingual fixed appliances They found that periodontal health could actually improve during the course of the treatment in cases treated with aligners . 72

73. Conclusion Not all malocclusions are amenable to treatment solely with the invisalign system. Treatment of many malocclusions with proper tip ,torque, arch form and aesthetic crown inclination is possible to achieve with aligners . Treatment using clear aligners is becoming increasingly common in orthodontics. A better understanding of how tooth movement is achieved may lead to treatments that are more efficient . All in all I nvisalign is a great alternative to braces ,owing to its comfort level and ease of use. Though its not very cost effective, we hope in the future newer technology and materials will make it more affordable. More research in the field of complex tooth movement is still needed, but apart from that, Invisalign has the potential to replace conventional orthodontic appliances. 73

74. References 1) orthodontics current principles and techniques – Graber, Varnsdall,Vig 2) Invisalign – Emperor’s New cloth – Indian journal of dental sciences june 2011 ;2;3 3) I nvisalign instruction manual – mcgill university 4) Aligner bio-mechanics - orthodontic clinical education corp. 5 ) Invisalign ClinCheck 3.0 User Guide 74

75. 6 ) Invisalign Orthodontic Treatment - Richard Bouchez 7) Clear Collection instruments for clear aligner treatments - Orthodontic Practice US Volume 6 Numbers 3 & 4 8) Smart Force features and Attachments – Invisalign. 75

76. Thank you 76