Objective: To assess the scientific evidence of the influence of some variables on smile attractiveness: orthodontic treatment, midline position, axial midline angulation, buccal corridor, and smile arc. Materials and Methods: Literature was searched through PubMed, Web of Science, Embase, and All EBM Reviews. The inclusion criteria consisted of studies written in English; published in the past three decades; concerning the influence of orthodontic treatment, midline position, axial midline angulation, buccal corridor, and smile arc on smile esthetics; and judged by a minimum of 10 raters. Quality features evaluated were adequate description of samples, absence of confounding factors, and description of methods used to evaluate the smiles and statistical analyses. Results: Initially, 203 articles were retrieved. Of these, 20 abstracts met the initial inclusion criteria and were selected. Thirteen articles were classified as high quality, seven as average, and none as low quality. Conclusion: Four-premolar extraction or nonextraction treatment protocols seem to have no predictable effect on overall smile esthetics, meaning that if well indicated, extraction in orthodontics does not necessarily have a deleterious effect on facial esthetics. The selected articles recommend that a small dental midline deviation of 2.2 mm can be considered acceptable by both orthodontists and laypeople, whereas an axial midline angulation of 10u (2 mm measured from the midline papilla and the incisal edges of the incisors) is already very apparent, and considering studies dealing with real smiles, buccal corridor sizes and smile arc alone do not seem to affect smile attractiveness. (Angle Orthod. 2011;81:153-161.)

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The aim of this study was to compare smile attractiveness between one, three, and four premolar extraction protocols in patients with Class II division 1 subdivision malocclusions and to analyse the aesthetic influence of buccal and posterior corridor widths on smile attractiveness. The sample consisted of posed smile photographs obtained from 66 subjects, divided into three groups according to the treatment-extraction protocol. Group 1 was treated with one maxillary premolar extraction included 23 subjects, group 2 was treated with four premolar extractions included 23 subjects, and 20 patients in group 3 were treated with three premolar extractions. Buccal and posterior corridor widths of each photograph were measured in proportion to the smile width. To rate the posed smile photographs, panels of 70 orthodontists and 46 laypeople used a 10-point scale. There were no significant differences in smile attractiveness scores between the three groups and between orthodontists and laypeople. Also buccal and posterior corridor widths did not differ between the groups and they did not influence the aesthetic scores. It was concluded that smile attractiveness is similar in treatment protocols of one, three, and four premolar extractions and that widths of buccal and posterior corridors do not influence smile attractiveness in these groups.

Anterior spaces may interfere with smile attractiveness and compromise dentofacial harmony. They are among the most frequent reasons why patients seek orthodontic treatment. However, midline diastema is commonly cited as a malocclusion with high relapse incidence by orthodontists.ObjectivesThis study aimed to evaluate the stability of maxillary interincisor diastemas closure and the association of their relapse and interincisor width, overjet, overbite and root parallelism.Material and MethodsSample comprised 30 patients with at least a pretreatment midline diastema of 0.5 mm or greater after eruption of the maxillary permanent canines. Dental casts and panoramic radiographs were taken at pretreatment, posttreatment and postretention.ResultsBefore treatment, midline diastema width was 1.52 mm (SD=0.88) and right and left lateral diastema widths were 0.55 mm (SD=0.56) and 0.57 mm (SD=0.53), respectively. According to repeated measures analysis of variance, only midline diastema demonstrated significant relapse. In the overall sample the average relapse of midline diastema was 0.49 mm (SD=0.66), whilst the unstable patients showed a mean space reopening of 0.78 mm (SD=0.66). Diastema closure in the area between central and lateral incisors showed great stability. Multivariate correlation tests showed that only initial diastema width (β=0.60) and relapse of overjet (β=0.39) presented association with relapse of midline diastema.ConclusionsMidline diastema relapse was statistically significant and occurred in 60% of the sample, while lateral diastemas closure remained stable after treatment. Only initial diastema width and overjet relapse showed association with relapse of midline diastema. There was no association between relapse of interincisor diastema and root parallelism.

Objectives: To assess the changes in the maxillary buccal alveolar bone during alignment without extractions. Secondarily, to evaluate the changes in arch dimensions and buccolingual inclinations of teeth and to identify risk factors for bone loss. Materials and Methods: Twenty-two adolescents with crowded permanent dentitions were treated without extractions with Damon 3MX brackets. Cone beam computed tomographic scans were taken before treatment (T0) and after alignment (T1). Bone thickness (BT) and height from the cementoenamel junction to the alveolar crest (BH) were evaluated at the maxillary central incisors, second premolars, and buccal roots of first molars. Changes in all variables from T0 to T1 were assessed. Correlations between bone changes and initial bone thickness, initial arch widths, initial crowding, amount of expansion, amount of tipping, and amount of molar rotation were calculated. Results: BT decreased and BH increased significantly for the incisors and mesiobuccal root of the first molars. Arch dimensions generally increased together with tipping. Bone loss was correlated with crowding and amount of expansion in the premolar region. Initially thinner BT was correlated with greater apical migration of bone for the incisors. Conclusions: Nonextraction alignment with self-ligating brackets led to arch expansion associated with tipping of teeth. Expansion related to alignment resulted in horizontal and vertical bone loss at the incisors and mesiobuccal root of the first molars. Thinner BTs and more severe crowding before treatment increased the risk for buccal bone loss. (Angle Orthod. 2018;88:748-756.)

Late pubertal patients with Class II division 1 malocclusion treated with fixed functional appliances associated with fixed appliances present similar soft tissue results as two-maxillary premolar extraction treatments.