title: Effectiveness of optical illusions  applied on a single composite resin veneer for the diastema closure  of maxillary central incisors.
abstract: OBJECTIVE
  To assess the esthetic effectiveness of four illusion techniques applied to a composite resin veneer for diastema closure between maxillary central incisors.
  
  
  METHODS
  An acrylic model with six natural maxillary anterior teeth was fabricated with a 2-mm diastema between the central incisors. Resin veneers were constructed on the left central incisor and the following cases were derived: V0: no veneer; V1: veneer without optical illusion features; V2: veneer with centralized interproximal ridges; V3: veneer with curved incisal edges; V4: veneer with gray pigment mesially/distally; V5: veneer with gray pigment on the developmental lobes. Digital printed photos of the models (13.2 x 17.8 cm, and 6.1 x 8 cm), with low, medium, and high smile lines and without a smile line (processed by Adobe Photoshop CS6) were shown to three groups of people (faculty members, senior undergraduate students, and patients; n = 25/group) for them to assess the overall size and width of the two central incisors. The results were analyzed by Pearson's and chi-square goodness of fit tests.
  
  
  RESULTS
  There was no significant influence in the estimation of the two central incisors as being the same size, according to the technique used (P = 0.869) and group of evaluators (P = 0.209). The estimated probability of assessing the tested incisor as wider was indicatively lower in V2 compared to V1 (adjusted odds ratio = 0.59; P = 0.088). The height of the smile line affected the evaluation of the veneers only in the large-sized photos.
  
  
  CONCLUSIONS
  No interference is the best esthetic decision concerning a 2-mm diastema closure when restoring only one central incisor with a laminate veneer. The next best option is to deliver a veneer with centralized interproximal ridges.
authors.forename: Thomai
authors.initials: T
authors.lastname: Katsarou
authors.forename: Maria
authors.initials: M
authors.lastname: Antoniadou
authors.forename: Efstratios
authors.initials: E
authors.lastname: Papazoglou
mesh_terms: D003188:Composite Resins; D003801:Dental Veneers; D003970:Diastema / Q000601:surgery*; D005260:Female; D006801:Humans; D007180:Incisor / Q000601:surgery*; D008297:Male; D008437:Maxilla / Q000601:surgery*; D009903:Optical Illusions
chemical_list: D003188:Composite Resins