Aesthetics is the branch of philosophy concerned with questions of beauty [Anike.C et al, 2015]. The concept of a ‘perfect appearance” forecasted by the media can influence the way the modern beauty conscious society thinks. Aesthetics is also implemented in dentistry and dental aesthetics refers to the subspecialty of odontology which provides beauty and harmony to a person’s smile [Manipal.S et al, 2014]. It is concerned with the correction of the smile, changing the facial profile and correcting jaw relations.
Good dental appearances can be a requirement of prestigious professions among some professional groups [Afroz.S et al,2013]. Smile makeovers can also improve a person’s self-esteem [Davis.G et al, 1998]. Therefore, there is an increased demand from the public for aesthetic dental treatment [Morley J et al, 2001]. This essay evaluates the systems used to record and replicate oro-facial related tissues. It also critically analyses how the oral cavity and craniofacial configuration influences dental and facial aesthetics. Facial aestheticsFacial aesthetics is based on principles such as symmetry and facial proportions.
Facial symmetry measures the bodily asymmetry which can impact judgments of the aesthetic characteristics of a person’s physical attractiveness [Grammer.K, 1994]. [Mealey.L et al, 1999] assessed the role of facial symmetry in relation to recognition of facial attractiveness. The symmetry and attractiveness were compared between developmentally unidentical monozygotic co-twins. The more symmetric twin was continually chosen as more attractive, suggesting that facial symmetry influences facial aesthetics. However, [Springer.N et al, 2007] studied the evaluation of manipulated images to find if asymmetry impacts beauty perception.
They found that minor lateral orbital and facial asymmetry doesn’t affect attractiveness and faces with a completely symmetric bilateral pair of nevi in the same lateral got the worst ratings. It was concluded there can be exceptions to the rule that symmetry is a characteristic of attractive faces.Fig.1 [Pauphoto,2018] Line of symmetry applied to a patient. Facial proportions also influence facial aesthetic. It is believed that human faces are built based on the Golden Ratio which shows an ideal proportion of two aspects of an object, with one aspect 1 Ѕ times longer than the other, a ratio of around 1. 618. The golden proportion (GP) divides the face vertically into equal thirds by horizontal lines adjacent to hair line, the nasal base and Menton. (Fig .2) [Kaya.K et al,2018]. [Pancherz.H et al, 2010] tested the validity of this ratio by testing whether facial beauty can be measured by comparing attractive and unattractive faces of females and males with regard to the presence of the GP. Inconsistencies to the GP for all variables were found more in the unattractive sample, which supports the concept of GP. However, [Anand.S, 2015] examined the existence of GP among 100 patients (50 males; 50 females). The results showed that the horizontal mean ratios for females as well as males were significantly different from that of golden ratio. It was therefore concluded that the GP should not be the only method of measuring beauty.Fig.2. [Pauphoto,2018] A face detailing ” 3rds relating to each other. Stomion is 1/3rd of total depth of S to MHowever, craniofacial configuration can affect facial and dental aesthetics because facial aesthetics has been linked to sagittal occlusal relationships (classes I, II and III) [Reis.B et al, 2011]. A class II division 2 malocclusion can change facial and dental aesthetics due to irregularity in bite characterised by a specific ratio of teeth and jaw bases as well as an adequate appearance of the face. It can cause a protruding nose and chin, retruding lips, concave and shortened lower third of the face as well as a gummy smile. (Fig. 3). Soft-tissue profile would also present a concave lower third of the face with a protruding nose and tip of the chin and retruded lips (Fig 4) [Perovic.T, 2017]. Fig.3 [Perovic.T, 2017]. Fig.4 [Perovic.T, 2017].An article by [Bishra.S, 2006] concluded that the incremental growth patterns in Class II deviation 2 don’t differ in magnitude from normal growth patterns. However, [Perovic.T, 2017] compared the characteristics of a profile face harmony in individuals with class II division 2 with class I jaw relationships and found that the characteristics of a facial profile of individuals with class II division 2 differ to a normal occlusion in terms of the position and prominence of the chin, the position of the upper and lower lip in relation to the Steiner and size of the facial angle.Fig.5 [Basavaraddi.S, 2016]. Fig.6 [Basavaraddi.S, 2016].The above patient has irregularly placed maxillary and mandibular teeth, a convex profile, recessive chin, decreased lower anterior facial height and increased gingival display [Fig 5]. She also presents a deep traumatic bite, and lingual displaced lower right lateral incisor [Fig.6]. The crowding could be treated with orthogenetic surgery and if there is no unlocking after alignment, bilateral sagittal split osteotomy can be carried out for the advancement of the mandible. Afterwards, fixed functional appliance can be used to correct the overjet [Basavaraddi.S, 2016]. Tooth loss can also affect facial aesthetics because it causes the lips and cheeks to sag. Dentures can give a more youthful appearance. [Fig.7]. In a study by [Raschke.G et al,2016], photographs of edentulous patients were compared after insertion of a CRDP and found major differences between pre and post denture treatment regarding facial measurements e.g. mouth width index. In addition, when arranging anterior teeth for edentulous patients, the patient’s gender and age should be considered. A younger appearance is created by setting the anteriors slightly prominent of the laterals and follow the lower lip contour. For a more masculine appearance, one incisor should be positioned ahead of the other and the canines should be prominent [Ishii. K et al,1990].Fig. 7 [Dental rehabilitation centre, 2006]Dental aesthetics When creating aesthetic restorations, the components of the aesthetic checklist which will be discussed should be followed. All aspects of tooth form e.g. shape, size and angulation of the tooth should be replicated when making a restoration. The general form/ shape of a restoration should conform to that of the fellow tooth in the opposite quadrant. [Williams. L, 1914] suggested that the shape of the face can determine the form of a restoration, because the central incisor is the inverted frontal view of the face [Pedrosa. V et al, 2011] evaluated the frequency of agreement between shape of the face and maxillary central incisor (MCI) and found there is a link between the two. However [Ibrahimagic.L et al, 2001] aimed to find the correlation between the face shape and tooth form by measuring 3 horizontal distances on the faces of their samples. They found that this correlation was found in only 30% of the sample, therefore disapproving William’s theory. Dimensions of a restoration should also be identified. This can be done with the application of golden proportion (GP) which suggests that a ratio of 1 is given to the lateral incisor regarding mesio-distal width. The central incisors will then have a 1.616 ratio and the canines will have a 0.618 ratio when compared to the lateral incisors. [Fig.8] [Murthy.B et al,2008]. [Nikgoo.A et al, 2009] assessed the validity of the golden ratio between the widths of the maxillary anterior teeth in people with attractive/ unattractive smiles. Maxillary central to lateral incisor ratio showed the GP in 50.3% of the participants with an attractive smile compared to 38.1% in the other group therefore supporting GP as a tool to prodfuce correct dimensions for aesthetic restorations. However, in a study by [Parnia. F et al.2010], the visible widths and lengths of maxillary right and left incisors were compared with golden standard. Significant differences were found between the width ratios of the left and right lateral teeth to the central teeth width and the golden ration GP. After calculating the correct dimensions of the restoration, a diagnostic wax up can be done prior to the fabrication of a restoration according to the correct dimensions to see if the patient is happy with the temporaries, as they will mimic the final restorations. When the patient approves of the temporaries, the final restoration should be made according to it [Simone.H et al,2008].Fig. 8 [Rabbanus.J ,2017]Another component of the aesthetic checklist is the zenith of the gingival contour which is the most apical position of the cervical tooth margin where the gingiva is most curved. The ideal relationship of the gingival height of contour would be a straight line, level with the horizontal plane [Basavaraddi.S, 2016]. In a study by [Maradi.A et al,2017] GZP and GZL were taken and it was found that such reference points could be used during treatment planning and creating a natural smile. However, in a study by [Lakshmi.S et al,2015] dental and facial measurements were made on 80 subjects: Central incisor width/length ratio, gingival zenith displacements were measured. However, most participants were fully satisfied with the appearance of their teeth, suggesting the discrepancies in teeth does not sabotage dental aesthetics.Fig.9 [Hernndez. R et al, 2013]The patient in fig.9 presents irregular zenith points and short teeth. A crown lengthening surgery can create new gingival margin levels to establish harmonious dental dimension. A gingival margin level should be established in concordance with the desired crown length, decreasing gingival exposition. Provisional teeth should then be replaced with new provisional teeth to provide better adjustment at the gingival margin. Next, final provisional teeth can be provided [Hernndez. R et al, 2013].Smile symmetry is another component of the aesthetic checklist. The dental midline is the vertical contact interface between two maxillary centrals and should be parallel to the long axis of the face. In a symmetrical smile the midline is aligned with the centre of the face. [Beyer. W et al,1998]. [Magne.P et al,2018] aimed to define the importance of symmetry in the smile. Images of a woman were edited to reproduce symmetry. 128 people choose the most desirable image. The participants mostly preferred a symmetrical smile which suggests that symmetrical smiles are considered more pleasant. However, in a study by [Pinho.S et al,2006] smiles were altered to show asymmetry of the gingival margin of a central incisor and a dental midline shift. Laypersons, orthodontists, and prosthodontists evaluated the original and the altered images. Laypersons saw no alteration which suggests that to the general public smile asymmetry doesn’t influence dental aesthetics.Fig 10. [Machado.A, 2014].The right and left central incisor of the patient in fig 10 have different width-height (W/H) ratio therefore creating asymmetry. Treatment would comprise 0.5-mm interproximal wear on the mesial and distal surfaces of right central incisor, followed by orthodontic space closure. This would help achieve maximum symmetry between central incisors [Machado.A, 2014].Tooth axis is another component of the aesthetic checklist. Axial inclination compares the vertical alignment of maxillary teeth to central vertical midline. From the central to the canine, there should be a progressive increase in the mesial inclination of each subsequent anterior tooth. With the centrals, it should be least noticeable and be more pronounced with the laterals and slightly more with the canines [Bhuvaneswaran.M,2010].The lower lip line is yet another principle of smile design. It is the height of the upper lip relative to the maxillary central incisors. An ideal smile arc has the maxillary incisal edges slightly contouring the lower lip (Fig 12). The ideal configuration of smile arc is a convex, consonant arc. On the other hand, when the incisal contour of teeth in the aesthetic zone does not follow the contour of the lower lip, the smile arc is differently classified [Machado.A, 2014].Fig 11. Axial inclination. [Dental aesthetics, 2019] Fig.12 [Machado.A, 2014].In addition, the gingiva acts as the frame for the teeth; therefore, the health of the gingiva, balance of the gingival level and interdental closure should be considered when fabricating aesthetic restorations. Healthy gingiva should fill the gingival embrasure right up to the contact area [Chiche. J et al, 1993]. A literature review by [Demir.F et al,2017] states that even when the teeth are at a good state and alignment, unhealthy gums can produce an unaesthetic appearance, suggesting gingival health influences dental aesthetics. Interdental closure is another principle of smile design. An interproximal contact area (ICA) is the broad zone in which two adjacent teeth touch. [Fig 13]. The increasing ICA helps make teeth appear of longer teeth by wider and extend apically to eliminate black triangles. However, interproximal contact point [ICP) is the most incisal aspect if the ICA. [Fig 14]. The incisal embrasures should also show a natural, increase in size or depth from the central to the canine. As a result, the contact point moves apically as we proceed from central to canine [Fig 15].