DISCUSSION
The interest of a multidisciplinary care is to limit the dental biological cost: the riziform tooth has a reduced dental support, the orthodontic treatment and the analysis of the situation beforehand make it possible to limit to the maximum the dental preparations, but also to limit the periodontal biological cost, since the orthodontic treatment can in certain cases avoid an useless periodontal surgery (35). We are however aware that the realization of an impression on a multi-attach appliance makes the reading of the plaster models difficult. Moreover, it is important to note that the notion of ”beautiful smile” remains a subjective notion depending on each individual. A study has shown that the appreciation of a smile varies according to the age of the evaluator. Older people are less fussy about black triangles than younger people, as is the uncovering of teeth by the lips when smiling (18). Some studies show an inter-sex difference on the judgment of a smile, women seem more critical than men (37) while other studies show that there are no inter-sex differences, especially concerning the appreciation of the mesio-distal diameter of the maxillary lateral incisors (38). In addition, overall, orthodontists seem more critical (39) towards a smile than a general practitioner. And people in the general population seem less critical than a general practitioner (24,40). However, in another study, the notion of “smile arc” seems to be evaluated identically between orthodontists, general practitioners and the general population (41). For this, from an esthetic point of view, it is important to focus more on the patient’s appreciation than on our own personal appreciation as a practitioner, and to take into account the differences in inter-individual appreciation (sex, age, origin, etc) and especially to clearly define the objectives of the protocol. The most conservative approach to correcting tooth shape is direct resin composite bonding because it can be achieved without removal of tooth structure. Recent esthetic composite resin materials have similar physical and mechanical properties to that of the natural tooth and possess an appearance like natural dentin and enamel. They offer an expanded range of shades and varying opacities designed specifically for layering technique whereas early brands of composite resins offered only “body” shades and appeared dull and dense. Treatment is usually completed in one appointment. In addition, direct resin composite bonding treatment is less expensive compared with ceramic veneers. In this case, we decided to set up a veneer on the left lateral because of its shape and the high inter-proximal space to fill, and to establish a direct resin composite on the right lateral because of the low inter-proximal space. If a veneer was set up, it would have led to unnecessary deterioration of the enamel.
Adhesive ceramic veneers constitute a minimally invasive therapeutic approach and are able to replace defective natural enamel with a more or less dandruff ceramic facet. This conservative technique, is very suitable to treat many clinical situations while preserving the vitality of the teeth. However the diagnosis and the indication have to be well defined, and the protocol has to be strictly followed.
DSD and mock up play a crucial role in our protocol. Not only do they facilitate the orthodontic finishing process (determination of the position of the tooth concerned, provision of a better bonding surface for the bracket), but they also guarantee an optimal final result and help with the preparation of the tooth (36). In our clinical situation, the M-D diameter of the laterals was within the norm compared to the MD diameters of the centrals, therefore the DSD provided little additional information. It is of particular interest in the case of severe dental dysmorphoses that result in excessively high MD diameters of the laterals, which inevitably lead to diastemas.
Furthermore, no study has dealt with the unsightly appearance of a diastema between a canine and maxillary first premolar in comparison with a diastema between a lateral incisor and maxillary canine. Despite the efforts made to limit diastema, in some situations diastema is unfortunately unavoidable, which can make the patient’s smile look unsightly (26). Several indices have been developed to determine the ideal mesio-distal diameters of the 6 maxillary anterior teeth, such as the Mavroskousfis index, which states that the sum of the mesio-distal diameters of the 6 maxillary anterior teeth is equal to the inter-alar distance + 7mm. The Lee index states that the mesio-distal diameter of the maxillary central incisor is equal to one quarter of the intercalar distance. In our clinical case, the inter-alar distance is 46mm and the sum of the maxillary inter-canal mesio-distal diameters is 44.6mm. If we applied the Mavroskousfis index, this would result in an overly palatal position of the maxillary sector and consequently a sub-nasal profile in retro-position. The Lee index was not applicable in our clinical case because the diameter of the central incisor was 8.2mm and the quarter of the inter-alar distance is 11.2mm. For these reasons, we therefore applied the rule of German et al. cited above.