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ePaper created 2016-09-22, 10:58:51 | version 1.38.0
science & practice 25th EAO Annual Scientific Meeting 14 Introduction Faced by a missing lateral incisor, practitioners often consider a wide range of issues and are also faced by numerous treatment options: – in a young patient, faced with a uni- lateral or bilateral agenesis, he has to choose between an orthodontic treatment that either opens up the spaces or closes them. This deci- sion, when taken early in the over- all treatment, will affect both the patient and their caregiver for a long time (Fig. 1); – in an adult patient, this is a conse- quence of bone, physiological, trau- matic or infectious resorption, which will result in a decision whether or not to recommend a bone reconstruction or a gingival augmentation. In every situation, the results will be judged by the patient and those around him. Since the lateral maxil- lary incisor is an integral part of the smile, aesthetic expectations are generally very high and, if the results do not meet the expectations, dis- appointment can be powerfully felt. When describing the different treatment stages, a number of pitfalls and difficulties will be highlighted and advice and clinical protocols will be given, in order to ensure that the results of this implant/prosthetic treatment are predictable and as aes- thetically attractive as possible. This first article is concerned with these issues as regards the preprosthetic stages; the second will consider the most important aspects of the pros- thetic stages as well as aesthetic out- comes and their evolution over the long term. Anamnesis Once the usual contraindications for oral and implant surgery have been eliminated, particular attention should be given to the patient’s an- swers concerning their smoking hab- its. Indeed, meta-analysis give an ac- curate picture of the consequences of smoking, with increases of: – peri-implantitis1,2 and bone loss2 ; – failure rates.3 The conclusions of Snider et al.4 can provide recommendations for the practitioner faced with a patient who is a smoker: – the best is to ask the patient to stop smoking...; – if this approach is not acted on, then the patient must be warned of the increased risk of failure and of postoperative complications. This last issue is important, as smoking can be considered a lost op- portunity as far as implant treatment is concerned. Clinical examination The smile line When replacing a tooth in an aes- thetic region, understanding the loca- tion of the smile line is one of the de- termining issues during the clinical examination. There are two factors to consider: the exposure of papillae and visibility of the collar of the lat- eral incisor, and there is one signifi- cant problem: any aesthetic deficit experienced by the patient tends to make them change their smile line, which can happen more or less as a conscious process and this can be a source of significant errors. Analysis of gingival composition is also a de- termining issue in positioning the col- lar of the lateral incisors in a location that is aesthetically optimal. The gull-wing profile, where the collar of the lateral incisors is slightly more coronal than that of the front teeth or the canine teeth, is considered to be more attractive according to Chiche5 (Fig. 2). Dental aesthetics As regards dental aesthetics, the proportions of the proposed implant supported tooth can reflect two differ- ent scenarios: – there is a unilateral missing tooth and the controlateral incisor has normal and aesthetically pleasing proportions. The objective will be to create a lateral incisor implant that is a mirror image; – with the same situation but where the controlateral incisor is small; this is a situation that occurs fre- quently in unilateral agenesis where the incisor that is present is riziform or, if there is agenesis of both lateral incisors, the clinical ex- amination should gather the infor- mation required to decide on the di- mensions and coronal axes of the proposed lateral incisors. An analy- sis of the occlusion and the dimen- sions of the central incisors are the clinical parameters that make it possible to establish the character- istics of the planned prosthetic teeth. The anatomy of the lateral incisor has been the subject of various pub- lications, including, notably, by Papathanassiou6 who defined aver- age dimensions and a typical form (Fig. 3a) and also presented numer- ous morphological variants affecting these dimensions and also other char- acteristics such as the crown/root ratio and the coronal and root axes (Fig. 3b). These morphological crite- ria, which can now be found using 3-D imaging, have had a significant influence on the location of implants in all spatial planes in order to achieve the goal of harmony of form and dimension. Other publications, such as those by Levin7 and Preston8 , make it possible to estimate the width of absent lateral incisors on the basis of the central incisors (Fig. 4). Implant location A clinically significant deficit sig- nals the need for reconstruction of hard tissue but, conversely, a site without a tooth with no loss of vol- ume should be subjected to a three-di- mensional X-ray, as thick soft tissue can hide a lack of hard tissue (Fig. 5). A thin tissue biotype or a lack of at- tached gingiva can be a sign that gin- gival augmentation surgery will be required, particularly if a bone graft needs to be performed. Occlusion For orthodontic treatments, the anterior guidance should be analyzed carefully. It can be tempting to in- crease the perimeter of the maxillary arcade in order to obtain, at the least, implant corridors that are sufficiently wide at the level of 12 or 22. However, an overjet will make it very likely Lateral maxillary incisor implant–Key issues for aesthetic success Drs Philippe Russe & Patrick Limbour, France Fig. 1 Fig. 2 Fig. 1: Agenesis of 22, opening of orthodontic space. Fig. 2: Line of intermediate smile. The smile uncovers the papillae and reaches the collar of the incisors (12 and 22 are supported by implants). O V M 10 mm 10 mm 25 mm 25 mm Fig. 3a Fig. 3b Fig. 3a: Average forms, types and dimensions of the lateral incisor according to Papathanassiou.6 Overall height: 21mm, coronal height: 9 mm, radical height: 12mm, mesiodistal cervical diameter: 5mm, mesio-distal coronal diameter: 6.5mm, vestibular-lingual cervical diameter: 5mm, vestibular-lingual coronal diameter: 6.5mm. Fig. 3b: Proximal view photographs showing ten anatomical variants of lateral maxillary incisors described by the author.6 Fig. 4 Fig. 5 Fig. 4: According to Levin, following the golden ratio, the width of the lateral incisor y = 0.62 x and, for Preston, it is 0.66 x (images from Papathanassiou).6 Fig. 5: Evidence of bone deficit at 22 (case shown in Fig. 1).6 Fig. 6: Simulation of location of 3mm6 implant in cross section (case shown in Fig. 1).6 Fig. 7: Evidence of radicular convergence. Fig. 8: Orthodontic layout of implant corridor. Fig. 6 Fig. 7 Fig. 8