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12 Attachments Bonding and Interproximal Reduction
12.1 Bonding Attachments Protocol

The following Align Technology recommendations are suggested for a bonding attachments protocol, as summarized below and in Fig. 12.1.

Fig. 12.1 Have materials and equipment ready before any appointment.

 Check the adjustment of the attachment template

 Isolate with Nola dry field cheek retractor and prepare teeth: apply etching for 30 s, wash the surface carefully and then dry until the surface of the teeth become completely white.

 Use the bond on the surface of the teeth and cure it following manufacturer’s instructions.

 Apply the composite roughly in the attachment template. Clinician must use one of the composites recommended by Align Technology to prevent erosion of the attachment or debonding. SmartForces are only guaranteed with certain composites, as attachments might change their shape or surface easily if made with different brands from those tested (refer to the Invisalign Doctor Site to check suggested composite brands).

 Place the template in the mouth and apply pressure while curing the attachments.

 Remove template and remove excess composite with a bur.

 Test first aligner fit. The active bevel of the attachment must be in contact with the aligner.

Repeat the same process in the other arch.

Show the patient how to insert and remove the first aligner.

Fig. 12.2 (a) Place composite on template and (b) ensure there is no composite excess. (c) Bonding is best performed by two operators and (d) start from distal to mesial to avoid unexpected light‐curing.

Following Align Technology’s instructions on composites is strongly advised, as they have been previously tested, and results optimised, which cannot be ensured when using other brands.¹

12.2 Interproximal Reduction Procedure

Interproximal reduction (IPR) is the term usually applied to the Invisalign technique for stripping. This is a clinical procedure characterized by the interproximal enamel reduction of the teeth.

When applied to orthodontics, the space created is used for tooth alignment in cases of crowding² and the camouflage of class II/III malocclusions with an overjet excess/lack,³ as well as improving dental aesthetics by teeth recontouring.⁴

It is important to develop a good technique as enamel irregularities/scratches, resulting from an inadequate technique could increase the susceptibility of these teeth to the accumulation of plaque. That said, it should be stressed that both clinical teams from Craig and Sheridan⁵ and Sheridan and Ledoux⁶ concluded that posterior teeth whose interproximal enamel were stripped were not more susceptible to decay or periodontal disease, so it can be considered a safe and convenient procedure.

Fig. 12.3 A metal interproximal reduction strip is the most common type used.

Any IPR should be performed upon the practitioner’s criteria, usually using any of the most common techniques:

 Manual diamond stripParticularly effective for <0.2 mm IPR, mostly on anterior teethStart with the thinnest stripPatient’s gums should be protected with any retraction technique

 Slow speed diamond diskFirst break tight contacts using diamond stripsTo isolate, use interproximal wedges to loosen contactsPatient’s soft tissues can be protected using a dental mirror

 High speed burSuggested for 0.5 mm IPRTo isolate, use interproximal wedges to loosen contactsBe careful around cervical regions to avoid ledgesUse water spray to reduce clogging and overheating

Fig. 12.4 A high‐speed bur interproximal reduction (IPR) is suggested for 0. 5mm IPR, using both interproximal bur (a) and (b) edge rounding one.

 Oscillating techniqueSingle/double sided disks used in conjunction with oscillating hand pieces for enamel reductionStart with the thinnest diskUse water spray

Suggested IPR Protocol

Anterior IPR:

 <0.4 mm: oscillating technique

 >0.4 mm: diamond disk + oscillating technique

Posterior IPR:

 <0.4 mm: oscillating technique

 >0.4 mm: diamond bur + oscillating technique

Fig. 12.5 Interproximal reduction and attachments removal bur set is ideal for an Invisalign practice.

Suggested IPR Procedure

 Check space between teeth to decide if IPR is required

 Check that the clinical situation is equal to the ClinCheck

 If the space is less than 0.4 mm, protect soft tissue with wet jet. Use 0.15 mm metal strip (both sides) to break the contact point. After breaking the contact point with this strip, use the oscillating technique from thinner to thickest until the desired measurement is achieved.

 If the IPR is more than 0.4 mm, rotatory instruments are necessary:Use drill with a high‐speed bur for posterior teethContra‐angle with diamond disk for anterior teeth, while always protecting the soft tissue

 Measure with gauges. Do not use pressure to insert the gauge. After 3 minutes, check it again as the resilience of the periodontal tissue can tend to close this space again.

 Polish and verify: polish with a polishing strip, apply fluoride varnish to prevent sensibility and note down in the patient file the amount of IPR done.

In our clinical template we register:

 IPR, in what stage of treatment this has to be done and between which teeth

 When we have to begin using elastics

 If we need to use any extra auxiliary techniques and in what stages

 If any attachment appears or disappear during the treatment

 Note potential problem teeth (the chief complaint of the patient and the black movement of the ClinCheck)

 The number of aligner we are on, and the next appointment with us

Fig. 12.6 Interproximal reduction has to be carefully planned and performed.

Notes

1 1 Barreda GJ, Dzierewianko EA, Muñoz KA, Piccoli GI. Surface wear of resin composites used for Invisalign® attachments. Acta Odontol Latinoam. 2017;30(2):90–95.

2 2 Betteridge MA. The effects of interdental stripping on the labial segments. Br J Orthod. 1981;8:193–7.

3 3 Vanarsdall RL, Jr. Periodontal‐orthodontic relationships. In: Graber TM, Vanarsdall RL JR, eds. Orthodontics: Current Principles and Techniques. 2000: pp. 801–38.

4 4 Zachrisson BU. Zachrisson on excellence finishing. Part I. J Clin Orthod 1986;20:460–82.

5 5 Craig G, Sheridan JJ. Susceptibility to caries and periodontal disease after posterior air‐rotor stripping. J Clin Orthod. 1990;24:84–5.

6 6 Sheridan JJ, Ledoux PM. Air rotor stripping and proximal sealants: an SEM evaluation. J Clin Orthod. 1989;23:790–4.

13 Digital Workflow

With any orthodontic technique, as with clear aligners, records routinely include study casts, intraoral and extraoral photographs, and panoramic and lateral cephalometric radiographs.

Additional diagnostic records may include a 3D cone beam computed tomography (CBCT) scan, periapical radiographs and any other diagnostic records necessary to begin the case.

One of the main advantages with clear aligners is that the whole procedure can be performed digitally, tracking every single movement and it is possible to ‘time lapse’ it.

13.1 Records
13.1.1 Photographs
Extraoral

Extraoral pictures should be taken with the following parameters on your camera:

 Manual mode

 F5.6

 1/125

 ISO 100

 Flash ¼ (ring flash is strongly adviced)

Fig. 13.1 Frontal, smile and lateral photographs.

A plain white background is recommended to avoid distortion on the images.

Intraoral

Lateral pictures must be exactly at 90 degrees: if lateral photos with any other angulation are sent, it will not be possible to check if the technician has set the occlusion for the real patient situation. For this, note that ‘teeth’ will be set up by the system with the pictures, so a poor quality picture might lead to a ‘false’ initial occlusion and, if this was not identified from the very beginning, it would lead to a ‘false’ or inappropriate treatment plan.

Fig. 13.2 90 degrees pictures are mandatory both in right (a) and left (b) intraoral views.

It is important to send an overjet photograph. In the intraoral frontal view, it is also possible to check the upper and lower midlines.

Fig. 13.3 Intraoral frontal (a) and overjet (b) pictures will help create a good treatment plan.

Occlusal photographs must be sent with articulating paper marks to assist the technician in setting up the initial occlusion.

Fig. 13.4 Blue or red ink on both upper (a) and lower (b) occlusal pictures will help setting initial occlusion.

13.1.2 Impressions: PVS vs Scan
PVS Impressions

Flexitime or Aquasil Ultra are the materials recommended for PVS impressions. It is important also not to use latex gloves to mix the PVS material, as they might interfere with its properties, and to follow the manufacturers’ instructions in regards to the working time of the product.

Choose the size of the tray carefully: in case of doubt, choose a bigger one and check that the third molars are included in the tray.

The impression has to be made in two stages: first the heavy material and second the light material.

Fig. 13.5 Polyvinyl siloxane (PVS) material placement.

Procedure:

 Mix the PVS material with vinyl gloves (do not use latex)

 Place a small amount of PVS material in the tray’s posterior zone

 Insert the tray and press slightly in the molar zone, use a smooth movement

Fig. 13.6 Inserting tray with polyvinyl siloxane (PVS) material into the patient’s mouth.

 Remove the tray immediately and exert pressure on the PVS material to open space for the light PVS silicon.

 Fill the tray with light silicon.

 Insert the tray into the mouth, it must be inserted from back to front in the upper arch and from front to back in the lower arch. Do it slowly to allow air to scape.

 Maintain the tray with no movement until the setting time is over.

A perfect impression is one in which the heavy PVS cannot or can only just be seen, and where we can visualize all the teeth, including the distal part of the second molars; 1–2 mm of gum should also be observed.

As a result of Align’s efforts and investment in research and development, digital detailing is now available to us, which is something that is not available with impressions for lingual appliances, for example, but nevertheless it is still essential to take a really good impression in order to achieve a great digital model.

Fig. 13.7 Upper (left) and lower (right) impressions.

Source: Images from Align Technology database.

Shipping boxes on the IDS Webstore, which will be delivered free of charge to the practice will need to be ordered to send PVS impressions. The impressions and patient prescription are placed in these boxes and sent to Invisalign, and instructions for this are provided the inside the boxes.

iTero Scan

The iTero Element 2 Intraoral Scanner is designed to fit in practice even better than before. Whether a general practitioner or orthodontist, the iTero Element is designed to deliver speed, reliability, intuitive operations and outstanding visualization capabilities that include:

 Next‐generation processor giving reduced scan processing and a faster start‐up time (can perform a full arch scan in as little as 60 seconds)

 Uninterrupted scanning: long‐lasting, rechargeable battery for easy mobility from surgery to surgery without plugging in or rebooting

 Stunning colour imaging: enhanced colour offers a more thorough look at the patient’s oral health

 High‐definition visuals: slim, 21.5‐inch monitor with 16:9 widescreen viewing format and improved resolution for highly detailed images

 Ergonomic wand placement: designed with a centre‐mounted wand cradle for easy ergonomics during scanning

 Smarter scanning: improved wand touchpad is as intuitive as gesturing on a smartphone: the touchpad can be used to switch between scanning segments or rotate the model on screen

Fig. 13.8 iTero scanner has several advantages, such as the Outcome Simulator

X‐rays

It is recommended that, as a minimum, both panoramic and lateral radiographs are submitted.

Fig. 13.9 Lateral and panoramic X‐rays.

13.2 Creating a New Patient Record

To create a new patient record, the facial and intraoral photographs and the X‐rays need to be uploaded. This, together with the patient data: name, surname, date of birth will create a unique profile on the Invisalign Practitioner Site.

Submitting a Prescription Form

 Create a patient

 Take patient's records

 Complete prescription form

 Package records: photos and iTero scan or PVS impression

Prescription Form

From this moment on, the process is entirely digital, as previously stated, this process can be 100% fully digital if a iTero scanner is used instead of PVS impressions.

After adding a new patient, select between the different treatments plans available according to the patient profile, choosing between:

 Adult (20 years or older)

 Teenager (13 to 19 years)

 Growing (6 to 12 years)

Next, select a product type:

 Aligners, for active treatment

 Retainers, for retention phase

 ‘Vivera retainers’ would only be selected at the end of the treatment, but at the start ‘Invisalign Clear Aligners’ will always be selected, which provides us with the following treatment options:

 Comprehensive, for a complex malocclusion

 ‘Lite’, for a simple treatment

 Express, for a relapse or really simple treatment

Finally, the prescription form needs to be filled in step by step depending on the malocclusion of the patient. How to fill in the prescription form is explained for every space plane at the beginning of each chapter.