Prerestorative Orthodontics: Veneers
Orthodontics is one of the key drivers of success in cosmetic dentistry, as space is needed for prosthetic restorations and cosmetic dentists require orthodontic collaboration to minimize tooth preparation in these patients. Clear aligners have been a really powerful tool in these situations, as many adults would refuse cosmetic dentistry in the past because they had to wear fixed appliances, which, in many circumstances, were viewed as incompatible with their professional and personal life.
That said, some patients do allow full comprehensive aligner treatment whereas some will just require a previous orthodontic preparation for the cosmetic procedure (mostly veneers) for which we again focus on three planes of space: transverse, sagittal and vertical.
Transversally, it is known that the golden proportion for teeth requires very concrete spacing in order to get the most natural result, which might already be ideal from the beginning or may require orthodontic intervention.
The most common intervention is Bolton discrepancy, which affects upper lateral incisors. This is sometimes resolved by reducing the width of the lower incisors by performing interproximal reductions. Another alternative is leaving space distal to laterals and bond veneers to them. Whichever is used, every space is related to the upper central incisor, as long as it has a regular size, as both laterals and canines to have to adapt to this.
The only exception to this is abnormal size or shape of the upper central incisors, in which we can refer to the contralateral central incisor or set a proportion according to most frequent sizes and shapes both in a man or woman smile.
For this transverse spacing we might work in two different directions according the protocol for protruding anterior incisors. Whenever there is a chance to procline, the result will be acceptable unless it comes from a retroclination of anterior incisors, as regular torque makes it difficult to create space because incisors are impacted into the cortical bone.
For this reason, a hypercorrection of this space opening in needed, together with attachments on lateral incisors, which are, as mentioned before, affects the tooth more, together with a small crown size, thereby leading to misfitting. Otherwise, there is not usually enough space to place veneers/crowns (as we can be seen in Figs 25.2 and 25.14, and in the Cases described in this chapter).
That said, transverse spacing might also be created by transverse development in patients with a compressed arch also needing an overcorrection from expected spacing, mainly because plastic amongst selected teeth has to be ‘seen’, therefore usually hypercorrecting the space by about 1.25 times.
Sagittally, an overjet is needed and is achieved with anterior torque correction by protrusion, for which both buccal and palatal Power Ridges are convenient, and lowering IPR to retrude the lower incisors. That said, it is important to understand what is meant in Align Technology by ‘overjet’, which might differ from what clinicians consider, especially since the introduction of the overjet/overbite tool on ClinCheck PRO.
In this sense, Align technicians and software measure overjet as the distance between the buccal surface of the lower incisor and half the crown of the upper incisor, instead of its palatal surface, therefore not being exactly the same concept you might be using. For this, it is essential to add 0.5mm (considering 1 mm as upper incisor average thickness) to the desired overjet agreed with the cosmetic dentist.
With regard to this, whenever there is a large posterior expansion, as a result of the ‘pearl necklace effect’ we have seen previously, in order to avoid additional aligners sets, natural arch depth loss will to be considered again: for example an estimate of 1mm would add an additional 1 mm overjet to achieve the desired result. Take into account the CAD designers measure the overjet in a different way including the thickness of the upper incisor. In order to communicate effectively with the CAD designer order a final virtual space of 1.5 mm between the palatal surface of upper incisors and the labial surface of lower incisors.
Finally, from a vertical perspective, anterior teeth have to be considered both from gingival and incisal perspectives in order to decide which is the priority for final aesthetics in the patient. In this the clinical conversations with the patient have a special importance with regard to the use of composite or ceramic final restorations after orthodontic treatment.
Cosmetics dentists will usually manage ‘pink aesthetics’, levelling incisors and canines at the same height, and laterals slightly lower (around 0.5 mm). There are several variations around this topic according to gender, ethnicity or even practitioners’ preferences, which might change the treatment plan, as used to happen with brackets bonding closer or distal to the incisal edge.
With regard to incisal edges, it is also commonly accepted that, as happened with width, central incisors are the reference to define the height of both laterals and canines, using these as a gold standard for length (as seen in Fig. 25.16).
Incisal edges are usually 0.5 mm ‘higher’ for laterals than central incisors and canines, which again might vary considerably depending on tooth wear, especially for canines, or any other aesthetic preference of the practitioner and patient.
From a vertical perspective, overbite again has to be clearly stablished from the very beginning of the treatment with the cosmetic dentist. This, if deep bite protocols are followed from the beginning, should not be overcorrected as results are highly predictable but, in order to facilitate cosmetic dentist work, can be magnified by slightly overcorrecting the lower curve of Spee by 0.5–1 mm lower intrusion from 33 to 43, with an open bite tendency to leave enough space for restorations to be naturally bonded.