Effect of maxillary median diastema on the esthetics of a smile


With the increasing demand for facial esthetics, patients’ expectations regarding dental treatment have increased. The treatment of maxillary median diastemas (MMDs) stands out as one of the most noticeable esthetic alterations performed on patients. The objectives of the present article were to evaluate the effects of MMD and its restorations on the esthetics of a smile and to determine the differences in esthetic perceptions among 3 different groups of patients: orthodontists, prosthodontists, and laypeople.


Printed photographic images were randomly arranged in an album that contained the original photograph of the smile, 8 photographs with digitally created diastemas (0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 4.0 mm, and 5.0 mm), and 8 with simulated restorations of these spaces. Each evaluator assigned scores to the images using a 100-mm visual analogue scale.


Orthodontists, prosthodontists, and laypeople presented similar perceptions regarding the levels of attractiveness of the original smiles and those of smiles involving restorations of diastemas with widths of 0.5 mm and 1.0 mm. The ratings assigned to the smiles with diastemas differed significantly from those of the corresponding restored smile with the same magnitude of diastema.


The prosthetic space closure of diastemas is better than leaving the space untreated. Restorations of MMD up to 1 mm perform similar to orthodontic closure. Larger MMDs are ideally treated with orthodontics because the restorative treatment is more invasive, leading to incremental damage to the dental tissues.


  • Orthodontic closure of medial maxillary diastema is better than restorations.

  • Orthodontic and restorative closures are for diastemas of up to 1 mm.

  • The diastemas were inferior to the original and restored smiles in all groups.

The growing demand for facial esthetics has increased patients’ expectations regarding dental treatment, which has led to the development of increasingly effective therapeutic interventions. Among the most noticeable esthetic concerns, in this study, we highlight medial maxillary diastema (MMD) that affects approximately 5%-20% of the patients seeking orthodontic treatment, with an incidence ranging from 1.6% to 25% that is inversely proportional to patient age. MMD can be defined as a space greater than 0.5 mm between the proximal surface of the maxillary central incisors that constitutes an aspect of normality during childhood.

The persistence of diastema in the permanent dentition presents a multifactorial etiology, and the prevalence of chronic inflammatory periodontal diseases in adults and the elderly seems to be an especially important factor involved in the development of MMD. ,

Adult patients who have MMD are considered by the general population to be less intelligent, less beautiful, less sexually attractive, and to come from a lower social class. There is no evidence to support that these perceptions are facts, but many studies have concluded that MMD is an esthetically unpleasant condition. It is very important to understand the factors that improve or decrease the level of attractiveness of a smile in order to create attractive smiles. However, most reports are based on subjective opinions of the authors , and not on evidence derived through hypothesis tests. , , To date, few studies , , have been aimed at evaluating the effect that the application of these norms of beauty and their variations have on the attractiveness of a smile. Many factors can affect the establishment of esthetic beauty standards, such as income, age, and culture, and this implies that the ideals of beauty are constantly changing. An example of this is the perception of the midline diastema in France, where the teeth on either side of a space are called “dents du bonheur” or “lucky teeth.” ,

MMD is commonly treated by orthodontists and prosthodontists, and there are 2 alternatives for the closure of the space: orthodontic movement and restorations in maxillary incisors. It is interesting to note that there are many case reports on these treatment strategies strategies, , several studies on the etiologies , of these diastemas, and a limited number of reports on the esthetic effects of the problem , , , , ; however, we were not able to identify studies that compared the esthetics resulting from the 2 treatment alternatives: orthodontic closure and the restoration of the space.

Thus, the objectives of the present article were to evaluate the effects of the progressive increase in the width of the MMD and its respective restorations on the esthetics of a smile and to determine the differences in esthetic perceptions among 3 different groups of individuals: orthodontists, prosthodontists, and laypeople.

Material and methods

The present study was approved by the Research Ethics Committee of the Faculty of Health Sciences of the University of Brasília.

To carry out this work, we chose a female subject on the basis of the following selection criteria: (1) have an esthetically pleasing face, (2) be a young adult, and (3) have a smile with characteristics close to normality. The subject was selected from a database of 85 frontal photographs of young female adult patients smiling, and the picture that most fulfilled the inclusion criteria was chosen by agreement of the authors.

The smile of this subject, who signed a free and informed consent form, was photographed ( Fig 1 ) with an SLR camera (Rebel XSi EOS; Canon, Tokyo, Japan) using a 100 mm macro lens (Canon) and a ring flash (Macro Ring Lite MR-14EX; Canon). The matrix photograph was obtained with a ruler outside the field of interest and was subsequently used to calibrate the digital changes. The matrix picture was digitally modified using the Corel Photo-Paint software (version 12.0; Corel Corporation, Seattle, Wash). After performing the changes, the nose, chin, and ruler were cropped out of the areas to be assessed. Initially, diastemas were created between the maxillary central incisors with widths of 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 4.0 mm, and 5.0 mm ( Fig 2 ).

Fig 1
Matrix smile.

Fig 2
Digitally created progressive diastemas. The numbers indicate the widths of the diastemas in millimeters.

In the case of smiles with diastemas that were 0.5-2.5 mm wide, resin restorations were simulated on the mesial surfaces of the maxillary central incisors. In the case of diastemas with widths of 3.0 mm, 4.0 mm, and 5.0 mm, the treatment simulations were made in another way. The central incisors were mesialized by 0.8 mm, and the simulated restorations filled the mesial and distal surfaces of the central incisors and the mesial surface of the lateral incisors ( Fig 3 ). This process mimicked the reduction of diastema with aligners or fixed appliances. After decreasing the diastema, spaces were created between the central and lateral incisors, allowing their restorations. This approach has been demonstrated previously.

Fig 3
Restored progressive diastemas. The diastemas with widths of 0.5-2.5 mm with simulated resin restorations on the mesial side of the central incisors. In the case of the diastemas with widths of 3.0 mm, 4.0 mm, and 5.0 mm, the central incisors were digitally mesialized by 0.8 mm, and the simulated restorations filled the mesial and distal surfaces of the central incisors and the mesial surface of the lateral incisors.

Printed photographic images (photograph size 13 cm × 18 cm, 1200 dots per inch, paper 300 g/m 2 grammage) were arranged randomly in an album on the basis of a random number table. The album contained the original photograph, 8 photographs depicting the diastema, and 8 with these spaces restored. All other facial features apart from the smiles were removed from the photographs to minimize the effects of potential confounding factors. The order in which the photographs were arranged was inverted in half of the albums in order to assess any possible order effect.

The 17 photographs were evaluated by 3 groups (n = 45 each) composed of orthodontists, prosthodontists, and laypeople. A sample size of at least 45 subjects from each group was set to detect an effect size coefficient for the visual analogue scale score of 0.8, with an α set at 0.05 and a power of 0.8. The specialists were randomly selected from the records of the Regional Board of Dentistry of the Federal District, Brazil. The laypeople were recruited in a shopping center located in the city of Brasília, Distrito Federal, Brazil. The criteria for the selection of laypeople were: (1) aged >18 years, (2) have a recognizable status of a layperson, and (3) voluntarily agree to participate in the study. The demographic data (eg, income, age, and sex) of the 3 groups of evaluators were not collected.

Each evaluator received an album and a score sheet with 100 mm visual analogue scales that were similar to those used in previous studies. , Evaluators had 20 minutes to complete the assessment. The intersection of the line on the far left indicated a rating of “very unpleasant,” and that on the extreme right indicated a rating of “very pleasant.” The evaluators were instructed not to compare the smiles among the photographs in the album, and the questionnaires were completed in the presence of one of the authors.

Statistical analysis

The SAS software (version 8.1; SAS Institute Inc, Cary, NC) was used for the statistical analysis. After normality was checked, analysis of variance was used to confirm the hypothesis that there were no differences in the ratings assigned to the various digitally altered smiles among each group of raters, and where appropriate, Newman-Keuls multiple comparisons tests were implemented as a post-hoc analysis. The smiles scores were used to assess whether the groups differed between each other with 2 analyses of covariance; 1 for the smiles with diastemas and 1 for the restored diastemas. The magnitudes of the diastemas were used as covariates. The level of significance, adjusted by the Bonferroni correction, was set at 1%.

The error of the method was calculated using the following formula:

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Jan 9, 2021 | Posted by in Orthodontics | Comments Off on Effect of maxillary median diastema on the esthetics of a smile
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