Kitabı oku: «Aligner Techniques in Orthodontics», sayfa 5
4.2 Effective Patient Communication
As in‐office communication is crucial and the best chance to interact with patients, we suggest having an Invisalign treatment coordinator in any office. Ideally, this would be a dental hygienist who:
Addresses the patient’s doubts about the treatment.
Explains the whole process (the patient journey).
Assists the patient from the moment they are given the treatment plan and quotation until they finish their treatment.
Fig. 4.3 A treatment coordinator is a key success driver for Invisalign.
5 Keys to Practice Growth
The ‘four Ps’ are the main growth drivers for Invisalign in our practices:
Progress: this technique is more advanced than any other in orthodontics – it is a 100% digital and customized technique.
Predictability: the chance of having selective anchorage during the treatment makes our movements more predictable.
Possibility of treating every malocclusion, even in mixed dentition.
Profitability: treat more patient with less chair time and fewer staff needed.
Fig. 5.1 If we plan our growth in advance, we will reach our goals.
5.1 How to Get the Best Results with Invisalign
We have come to the conclusion that the keys for success with Invisalign rely on:
Adequate patient selection (motivate the patient, show them in every appointment the results he or she is obtaining due to the use of the aligners)
Clear goals of treatment in every plane: transversal, sagittal and vertical.
Being very specific with the technician (in your instructions): communicate not only what you want to achieve but also how you want to obtain your treatment goals and the staging of movements needed for this particular malocclusion.
A thorough dynamic evaluation of the ClinCheck, considering staging, differential anchorage, looking for predictable movements while avoiding those outside the predictability range of the aligners shown as black dots on the tooth movement assessment tool (TMA).
6 Patient Selection
The Invisalign selection tool is a guide provided by Align Technology to help choose between the different treatment options that Invisalign provides, according to the patient malocclusion. This is a tool that might be used before sending the case in order to assess the predictability of the case (simple, green/moderate, blue/difficult, black) as well as the treatment option from the Align portfolio. During the learning curve, clinicians usually do this evaluation ‘automatically’, but we still think it is useful for beginners.
Based on Align’s ‘big data’ it is possible to predict accurately the outcomes from every tooth movement. This is really important in order to achieve excellent results, as the practitioner will need to understand how to make movements possible using auxiliary techniques (which relies on experience), alongside aligners or attachments (which is what this tool ‘analyses’).
Fig. 6.1 Invisalign evaluation tool.
7 Predictability of Movement
Movements are classified into three colours, according to their predictability:
Fig. 7.1 All treatment predictability can be checked with the Invisalign evaluation tool before sending the case.
7.1 Treatments to Gain Familiarity with the Technique
Class I < 6 mm spacing or crowding.
Deep bite < 4 mm
Open bite < 2,5 mm
Class II < 4 mm
Class III < 2 mm (distalization of lower molars by tipping the lower molars Crown to distal without moving the roots)
Midlines shift < 3 mm
8 Types of Treatments with Invisalign
Currently, although this may change in different parts of the world and in the future as a result of Align Technology commercial policies, the different options that Align provides according to the malocclusion of our patients are indicated in Fig. 8.1.
Fig. 8.1 Align Technology’s 2021 portfolio.
9 Pillars of the Invisalign Technique
The Invisalign system is not just a set of aligners, as other resources are needed to achieve success in each case. Based on this, we describe five pillars of the technique, which are:
Aligners
ClinCheck software
Attachments and features of SmartForce
Auxiliary techniques
Technicians
9.1 Aligners
Aligners are made from SmartTrack material, a patented plastic formula exclusively designed this purpose, while attachment templates are made with EX 15 and Vivera retainers with EX 40.
Characteristics of the SmartTrack technology:1
Creates a soft and constant force.
Is more elastic than other aligner materials, which results in a longer working period.
Better adjustment to the teeth than any other alternative.
Easier to use and provides an easier way of placing and removing the aligner.
Every aligner makes:
0.25 mm of lineal movement
2 degrees of angular movement to correct rotations
1 degree of torque movement (lingual–root torque or labial–root torque)
In cases where we want to slow down the amount of movement, this can be requested from the technician, which will change Align’s default parameters to 50% (half of the movements indicated above).
Aligners are created to be used 22 hours per day, with changes depending on the amount of movement every 7, 10 or 14 days.
9.2 ClinCheck Software
This application, created by Align Technology, was designed specifically for practitioners. ClinCheck provides a 3D virtual representation of a treatment plan derived from the orthodontic prescription.
Each practitioner is able to send information back and forth with Align as changes are made to the treatment plan, and then aligners are manufactured in accordance with the finalized plan and sent directly to the practitioner to begin the patient’s treatment.
9.3 Attachments and Features of SmartForce
These are attachments composite structures that are bonded to the patient’s teeth in order to help achieve the movements previously planned on the ClinCheck software. They can be ‘conventional’, with standardized shapes and sizes, or optimized, where a shape and size is determined by the software based on each patient and tooth. They are bonded throughout the treatment and will be removed at the end of it.
In 2013, Align Technology developed the Smartforce Features in order to create the optimal forces to move the teeth in a predictable way. They can be placed.
On teeth, as optimized attachments
On the aligner, as pressure points or power ridges
Full information of these will be delivered in later sections of this book.
9.4 Auxiliary Techniques
As stated previously, clear aligner therapy needs other forms of auxiliary techniques, such as elastics, buttons, Powerchains, Temporary Anchorage Devices (TADs) and others, just as we do with fixed appliances in order to make treatments more predictable and more efficient.
We will explain some of these auxiliary technique in the troubleshooting and auxiliary techniques section but it must always kept in mind that a great result with aligners needs a great practitioner using the five pillars: it is not just a matter of plastic and elastic, but an orthodontic treatment based on mechanics, forces and a detailed treatment plan that has to include every tool in our ‘ortho’ arsenal.
9.5 Technician (CAD Designer)
ClinCheck software allows practitioners to plan occlusion and tooth position but other changes, such as staging and teeth extraction still need collaboration from an Invisalign CAD designer. This makes these individuals really important to the treatment outcome and requires practitioners to adapt to the ‘technician language’ in order to achieve the best result from the aligner technique.
Note
1 1 Bräscher AK, Zuran D, Feldmann RE Jr, Benrath J . Patient survey on Invisalign® treatment comparen the SmartTrack® material to the previous aligner material. J Orofac Orthop. 2016; 77(6):432–438. Epub October 24, 2016.
10 Conventional Attachments
Conventional attachments are passive attachments that increase the engagement of the aligner onto the tooth. They act as a handle for the aligners to move teeth. They can be placed via written request to the technician or by using the drag and drop feature on the 3‐D controls.
There are three types of conventional attachments:
Ellipsoid attachments: Used for retention or anchorage when the tooth surface area is limited, for example for peg‐shape lateral incisors or the lingual surface of a lingually inclined mandibular second molar.Fig. 10.1 Ellipsoid attachments.
Rectangular attachments: These are passive attachments that can be vertical or horizontal. By default, they are placed in the middle of the tooth crown, but can be moved to any desired position to facilitate the mechanics that have been planned for the case.Horizontal: can be used for root control, especially for labial root torque on the molars. These can also be used in short crowns in order to increase the retention of the aligners, which is part of the standard Align’s protocols for patients that are still growing in interventions such as mandibular advancement or first protocols (similar to this, but optimized). In unilateral crossbites, horizontal rectangular attachments are used in the side without the crossbite in order to provide anchorage to correct the unilateral posterior crossbite on the contralateral side. This will be explained in Chapter 17, but they help to control the root torque so as to create an ‘en masse’ movement of not just the crown but of the whole tooth body.Fig. 10.2 Horizontal attachments have great clinical effects on transverse plane. Ellipsoid attachments.Vertical: these are used for root control when the software cannot place optimized root control attachments, such as mandibular incisors in cases involving the extraction of one lower incisor.Fig. 10.3 Conventional attachments are selected whenever there are no optimized ones available.
Bevelled attachments: both horizontal and rectangular vertical attachments can be bevelledHorizontal attachments can be bevelled to the occlusal (HBO) or to gingival (HBG) to help with intrusion or extrusion movements:For extrusive tooth movements on posterior molars, a horizontal attachment bevelled to gingival can be usedFor intrusion, use the horizontal attachment bevelled on the occlusal on the teeth adjacent to the one that has to be intrudedFig. 10.4 Extrusion attachments are placed on teeth adjacent to the ones to be intruded, so as to create a counter‐movement that will lead to a force couple. This is a great example of how biomechanics are applied on aligners.Vertical attachments can be bevelled to mesial (VBM) or to distal (VBD): for rotation movements when the software has not placed optimised rotation attachments, for example when correcting first molar rotation. The bevelled surface is the active one, as the bevel provides a flat surface for the aligner to push against to achieve the desired tooth movement.Fig. 10.5 Vertical attachments bevelled to mesial (left) and distal (right).
Conventional and optimized attachments might have similar functions:Double root control attachment: AT conventional rectangular verticalOptimized rotation attachment: AT conventional rectangular vertical bevelled to mesial VBM or distal VBDOptimized extrusion attachment: AT conventional horizontal bevelled to gingival HBGFig. 10.6 Conventional attachments might be placed to achieve similar movements to the optimized ones.
10.1 Features of SmartForce
10.1.1 Optimized Attachments
These area attachments with different characteristics from the conventional ones. They are:
Designed to provide optimal force to achieve a more predictable movement
Tailor‐made for each tooth’s width, long axis and contour
Positioned precisely to deliver the forces while simultaneously eliminating interferences
All these characteristics are defined by the ClinCheck software and do not permit changes by the practitioner, a feature that may change in the future.
Fig. 10.7 Research and development investment has led to a very powerful biomechanical system.
Optimized attachments provide SmartForces applied to the teeth. They provide the amount of force necessary to create the ideal movement of the tooth. In addition:
They are automatically placed by the software when it detects certain thresholds of tooth movement. They are designed to control the point of application of the force, the direction of the force and the amount of force applied. Every optimized attachment is customized to each individual tooth.
They have an active surface that contacts with the aligner. Its active surface varies in geometry based on the unique morphology of each tooth. The aligner is designed at a more acute angle than the active surface on the attachment in order to exert a force on the active surface to move the tooth in the desired direction. As a result of this, the size of the attachment on the tooth will differ from the size of the space in the aligner for attachment (reservoirs).
If an optimized attachment needs to be replaced midway through treatment, the clinician will need to use the attachment template to re‐bond the attachment, instead of using the last aligner.Fig. 10.8 Conventional dental composite is the material chosen for attachments.
In the past, the practitioner could not ask the technician to place an optimized attachment, but could ask for the movement so the software would place them. For example, if an optimized extrusion attachment on a certain tooth was required, we would ask for more than 0.5 mm of extrusion in that tooth and the software would place the attachment. However, it is now possible to ask for optimized attachments even if the movement is not supposed to happen (or it is under the threshold), which could prove helpful for certain situations (lower premolar anchorage to level lower Spee curve by incisor intrusion). It should be noted that:
They are individualized for the tooth and for the specific movement that particular tooth needs
Their position, shape or size cannot be changed
They cannot be placed lingually
They are not compatible with other lingual attachments or SmartForces
Currently available optimized attachments include:
Optimized rotation attachment (for rotation movements in canines and premolars)
Optimized extrusion attachment (for extrusion movements in incisors, canines and premolars)
Optimized root control attachment (for root control in incisors, canines and premolars)
Optimized attachment for upper lateral incisorsMultiplane attachment (for lateral incisors with rotation and vertical movement)Optimized support attachment (to support lateral incisors when there is an intrusion movement on adjacent canine or central incisors); deep bite correction.
Optimized attachments on molars:Multiplane attachment (for molars with rotation + vertical movement)Extrusion optimized attachments (for extrusion movements on molars)
Optimized support attachments: to provide support for predictable dental arch expansion in mixed dentition.
Optimized Rotation Attachment
These are placed for rotation of canines and premolars greater than 5 degrees:
Fig. 10.9 Placement on canines and premolars.
Placed when more than 5 degrees of rotation is needed.
The predictable rotation is between 30 and 45 degrees.
If one needs to be replaced for a conventional one, it will be a vertical rectangular attachment bevelled to mesial or distal.
Optimized Extrusion Attachment
Designed for extrusion of incisors, canines and premolars, these attachments are bonded in the middle of the crown:
They are placed when the extrusion is more than 0.5 mm and have a wedge shapeFig. 10.10 Placement on incisor.Fig. 10.11 Placement on premolar.
When they are placed on lower premolars, they are used as an anchorage for the anterior intrusion of the incisors and they have a different shape
They can also be activated to provide an extrusion force on the premolars during the anterior intrusion
When extrusion of the four upper incisors is greater than 0.5 mm the four teeth will act as a single unit
We will look at these attachments in more detail later, but note that they are mandatory when an anterior open bite is part of the patient’s malocclusion, otherwise the aligner will not be able to apply a clean extrusion vector.
Fig. 10.12 The right side shows how anterior extrusion attachments help to create a counterforce to posterior intrusion, achieving predictable movements.
Optimized Root Control Attachments
These are are designed for upper central upper incisors and lower canines, where they will control root movement, for tipping management and ‘en masse’ translation:
They have two active surfaces and are placed when there is a translation of the tooth centre of resistance greater than 0.75 mmFig. 10.13 The figure on the right shows how optimized root control attachments create a couple of forces to improve root tipping.
These are not available for lower incisors
They can be placed in two ways:In opposite orientations on both central incisors (like a mirror image): they are used to close a diastema (mesial root tipping of 11 and 21 to close the diastema)Parallel to each other on both central incisors (they are placed in the same directions in both central incisors). In this case they are used to move the upper midline in one direction
They are automatically placed by the software:When the centre of the root on upper and lower canines and premolars moves more than 0.5 mmWhen the centre of the root on upper central incisors moves more than 0.75 mmThey can also be placed in lateral incisors and premolars, but because of the short crown, instead of a ‘double attachment’ it is sometimes shown as a half‐moon and a pressure point applied on the aligner’s lingual surfaceFig. 10.14 Pressure points are usually associated with attachments whenever short clinical crowns are detected.
Optimized Attachments for Lateral Incisors
Multiplane Attachment
Placed when the lateral incisors need intrusion or extrusion while simultaneously requiring rotation, torque or tipping movements
They have an active surface on the attachment and a lingual pressure pointFig. 10.15 Combination of attachments and lingual pressure points help creating an excellent force system.
