Impact of altered gingival characteristics on smile esthetics: Laypersons’ perspectives by Q sort methodology

Introduction

Smile esthetics includes the white esthetics related to the teeth and the pink esthetics related to the mucosa. Many surveys have been conducted to evaluate laypersons’ perceptions to altered dental characteristics, but few have focused on the soft tissue factors. This study was designed to determine the perceptions of laypeople to variations in soft tissue esthetics during smile.

Methods

An ideal smile photograph was intentionally altered to produce variations in gingival inflammation, pigmentation, contour, position of free gingival margins (with and without recession), zeniths, and interdental papilla. Sixty-seven images thus produced were rated for attractiveness by 100 laypersons with the Q sort technique.

Results

Variations in interdental papilla (black triangles) were the most negatively ranked gingival factor by laypersons closely followed by color changes of the gingiva due to inflammation and pigmentation. Alteration of gingival contour and gingival zenith had the least impact on smile esthetics, and changes in the free gingival margin with and without recession were moderately perceived. Furthermore, laypersons considered unilateral or asymmetric alterations more unesthetic compared with bilateral or generalized alterations for factors such as free gingival margin without the recession, and color changes caused by inflammation and pigmentation.

Conclusions

Laypersons have considerable negative perception to asymmetric gingival alterations and to optical color changes caused due to black triangles, inflammation, and pigmentation of the gingiva. Whereas alteration in gingival contour and zenith have least impact on smile esthetics.

Highlights

  • Laypersons’ perceptions of smile esthetics were evaluated with Q sort methodology.

  • Color changes from black triangles or gingival inflammation or pigmentation were perceived.

  • Changes in gingival contour and zenith had the least impact on smile esthetics.

  • Changes in free gingival margin with or without recession were moderately perceived.

A beautiful smile is desirable. Patients from all walks of life tend to express their wishes for a perfect smile. Some visit the doctor precisely for this purpose. An enticing smile demands a balance between macro, mini, and micro esthetic factors that include white esthetics related to teeth and pink esthetics related to the gingiva. Although many studies have been published on perceptions of laypersons and dentists to altered dental esthetics, few have focused on the gingival component of mini and micro esthetics. Gingival factors such as shape and contour, position of free gingival margins and zeniths, color and pigmentation of the gingivae, position of the papilla, inflammation, scalloping, and recession make important contributions to soft tissue esthetics. A smile architect pays much attention to these minute details for designing a smile. Designing the teeth in the confines of the gingival architecture impacts smile esthetics to a considerable extent. An uneven free gingival margin height or inflamed gingivae at the anterior teeth can have a dramatic impact on esthetics. Although the position of the zenith or papillary position appears to be a small detail, it can greatly influence the axial inclination and emergence profile of the teeth, and even a small black triangle can spoil all efforts to create a beautiful smile.

To improve the gingival curtain, an interdisciplinary treatment is required spanning orthodontics, periodontics, prosthodontics, endodontics, and at times oral surgery. Procedures such as periodontal plastic surgeries, intrusions, extrusions, or LeFort surgery may be needed to optimize gingival esthetics.

The purpose of this study was to evaluate how a layperson perceives these altered gingival characteristics in both unilateral and bilateral situations. We also aimed to identify the gingival characteristics that are most negatively and positively marked. We attempted to identify characteristics of a perfect smile. The extent or degree to which the altered gingival characteristics are unnoticed by laypersons will help to determine the characteristics that are noticed and consequently matter.

Materials and methods

Institutional ethical clearance was obtained from Jamia Millia Islamia in New Delhi, India, before the study, and written informed consent was taken from all participants. The survey was conducted over 3 months.

A frontal close-up smile of a 22-year-old student in the dental college was selected for the study (control image, Supplement 1 ). The student’s smile was selected because it was considered highly attractive according to the objective principles of the ideal smile described in the literature. The student had no history of orthodontic treatment or restorations of anterior teeth. The image was cropped in Photoshop (version CS2; Adobe Systems, San Jose, Calif) to show only the lips, nasal tip, and mentolabial fold to reduce distractions. The image was then condensed so that each millimeter measured on the digital and printed image was equivalent to each millimeter measured clinically on the patient, using the maxillary central incisor as the reference. This image of an ideal smile was intentionally altered to produce the desired smile with characteristic manipulations (described below). There were 65 modifications. Two copies of the original unaltered ideal smile (control) were added to the 65 photographs to check for reproducibility of the results. Thus, a total of 67 images were produced. Final images were digital files with 300-dpi resolutions. The 3.5 × 5-in images were professionally printed using specialized digital equipment and a photo album was assembled with all images in random order.

The ideal smile image was altered to produce the following modifications: (1) discrepancies in the position of free gingival margin without recession ( Fig 1 ), (2) variations in the positions of interdental papilla ( Fig 2 ), (3) discrepancies in the position of zenith ( Fig 3 ), (4) color changes due to varying degrees of inflammation of the gingiva ( Fig 4 ), (5) color changes due to varying degrees of pigmented gingiva ( Fig 5 ), (6) discrepancies in the position of the free gingival margin with recession ( Fig 6 ), and (7) varying contours of the gingiva ( Fig 7 ).

Fig 1
Discrepancies in the position of free gingival margin without recession: A, free gingival margin of canine reduced up to the level of the lateral incisor bilaterally; B, free gingival margin of canine below the level of the lateral incisor bilaterally; C, free gingival margin of canine above the level of the central incisor bilaterally; D, free gingival margin of canine reduced up to the level of the lateral incisor unilaterally; E, free gingival margin of canine below the level of the lateral incisor unilaterally; F, free gingival margin of canine above the level of the central incisor unilaterally; G, free gingival margin of canine, lateral and central incisors at the same level unilaterally; H, free gingival margin of canine, lateral and central incisors at the same level bilaterally; I, free gingival margin of central incisor above the level of the canine bilaterally; J, free gingival margin of central incisor above the level of the canine by 2 mm bilaterally; K, free gingival margin of central incisor above the level of the canine by 1 mm unilaterally; L, free gingival margin of central incisor above the level of the canine by 2 mm unilaterally; M, free gingival margin of the central incisor reduced up to the level of the lateral incisor unilaterally; N, free gingival margin of the central incisor reduced below the level of the lateral incisor unilaterally; O, free gingival margin of the central incisor reduced up to the level of the lateral incisor bilaterally; P, free gingival margin of the central incisor reduced below the level of the lateral incisor bilaterally; Q, free gingival margin of lateral incisor above the level of the canine or central incisor bilaterally; R, free gingival margin of lateral incisor above the level of the canine or central incisor unilaterally; S, free gingival margin of lateral incisor below the level of the canine by 2 mm bilaterally; T, free gingival margin of lateral incisor below the level of the canine by 2 mm unilaterally.

Fig 2
Variations in the position of the interdental papilla: A, 1-mm black triangle between the maxillary central incisors; B, 2-mm black triangle between the maxillary central incisors; C, 3-mm black triangle between the maxillary central incisors; D, 1-mm black triangle between the 6 maxillary anterior teeth; E, 2-mm black triangle between the 6 maxillary anterior teeth; F, 3-mm black triangle between the 6 maxillary anterior teeth.

Fig 3
Discrepancies in the position of zenith: A, bilateral canine zenith shifted mesially; B, bilateral central incisor zenith shifted mesially; C, bilateral lateral incisor zenith shifted distally; D, bilateral lateral incisor zenith shifted mesially; E, unilateral canine zenith shifted mesially; F, unilateral central incisor zenith shifted mesially; G, unilateral lateral incisor zenith shifted mesially; H, unilateral lateral incisor zenith shifted distally.

Fig 4
Color changes due to varying degrees of inflammation of gingiva: A, papillary gingivitis; B, marginal gingivitis; C, generalized gingivitis.

Fig 5
Color changes due to varying degrees of pigmented gingiva: A, patchy pigmentation; B, pigmentation in bands; C, generalized pigmentation.

Fig 6
Discrepancies in the position of free gingival margin with recession: A, 1-mm recession in canine unilaterally; B, 2-mm recession in canine unilaterally; C, 3-mm recession in canine unilaterally; D, 1-mm recession in canine bilaterally; E, 2-mm recession in canine bilaterally; F, 3-mm recession in canine bilaterally; G, 1-mm recession in central incisor bilaterally; H, 2-mm recession in central incisor bilaterally; I, 3-mm recession in central incisor bilaterally; J, 1-mm recession in central incisor unilaterally; K, 2-mm recession in central incisor unilaterally; L, 3-mm recession in central incisor unilaterally; M, 1-mm generalized recession; N, 2-mm generalized recession; O, 3-mm generalized recession; P, 1-mm recession in lateral incisor bilaterally; Q, 2-mm recession in lateral incisor unilaterally; R, 3-mm recession in lateral incisor bilaterally; S, 1-mm recession in lateral incisor unilaterally; T, 2-mm recession in lateral incisor unilaterally; U, 3-mm recession in lateral incisor unilaterally.

Fig 7
Varying contours of gingiva: A, accentuated gingival contour bilaterally; B, denuded gingival contour bilaterally; C, accentuated gingival contour unilaterally; D, denuded gingival contour unilaterally.

Each esthetic characteristic was altered with progressive variations of the original smile photograph both unilaterally and bilaterally. The alterations are described in Supplement 2 .

The evaluators consisted of 100 laypersons (45 men, 55 women). A sample size of 100 was used in this study because it is rare to administer a Q sort with more than 100 participants. The participants’ viewpoints can be shown effectively with a smaller participant group of 40 to 60 subjects.

The participants were required to have at least intermediate-level qualification and a complete or an incomplete college degree. They were randomly selected from the students enrolled in various courses at Jamia Millia Islamia. Their ages were between 18 and 40 years. Basic information such as ethnicity, education, and socioeconomic status was gathered. Any previous professional dental affiliation disqualified a respondent from participation.

Each rater was given brief information about the study without disclosing the characteristics that were altered. The raters were asked to evaluate the attractiveness of the images using the forced distribution Q sort methodology. A 13-point scale was used with ranking values ranging from −6 to +6. A table containing 13 columns was drawn showing ratings from −6 to +6, with −6 as the most unattractive image, and +6 as the most attractive image ( Fig 8 ). The 67 photographs was presented to the evaluators who were instructed to arrange them in the 13 columns according to their personal esthetic preference. From the 67 photos, they were instructed to select the 2 most attractive and the 2 least attractive photographs and place them in the +6 and −6 columns, respectively. From the remaining 63 photographs, they were to select the 3 most attractive and the 3 least attractive photographs and place them in +5 and −5 columns, respectively. Continuing with this process, the evaluators were asked to select the 4 most attractive photographs, followed by the 3 most attractive and so on. The same process was used for the least attractive pictures. In the end, the evaluator was left with 11 photographs that were placed in the category 0, or the neither attractive nor unattractive category. The maximum number of images that could be assigned to each ranking position was also mentioned for ease of understanding. This is the forced Q sort methodology whereby the evaluators are forced to put a defined number of photographs in each column. Once the Q sort was accomplished, they were again given some time to check that all photographs were rated and arranged according to their esthetic preference. They were then instructed to leave the Q sort intact so that the scores could be recorded. On average, each evaluator took 15 to 20 minutes to complete the survey.

Fig 8
Example of the Q sort configuration.

Statistical analysis

The descriptive statistics were presented in terms of frequency (counts) and percentages in different categories for the qualitative variables and for the quantitative variables. For the quantitative variables they were presented as range (minimum and maximum) and as means and standard deviations, or medians and standard errors of the mean. The statistical significance of the quantitative variables having paired observations was carried out by paired t tests or nonparametric Wil-coxon signed rank sum tests, if the data did not have a normal distribution. The goodness of fit of the two control photographs(C and C+) was determined by chi-square tests and McNemar-Bowker tests. The level of significance was taken as 0.05 (5%). The data were analyzed by using statistical software (version 16.0, Statistical Package for the Social Sciences; SPSS, Chicago, Ill).

Results

Table I refers to the rating of the 7 variables and the control group, or the intergroup comparison. The ideal photograph (control group) was rated the highest for attractiveness, whereas the variation in the position of interdental papilla (black triangles) was the most negatively rated. The factors were rated in decreasing order of attractiveness as follows: control images, discrepancies in the position of zenith, varying contours of gingiva (scalloping), discrepancies in the position of free gingival margin without recession, discrepancies in the position of free gingival margin with recession, color changes due to varying degrees of inflammation of gingiva, color changes due to varying degrees of pigmented gingiva, and variations in the positions of interdental papilla (black triangles).

Table I
Intergroup comparisons
Factor Name Mean SD Ranking according to mean
8 Control group 3.9350 1.73882 1
3 Discrepancies in the position of zenith 1.8750 1.32728 2
7 Varying contours of gingivae (scalloping) 1.8125 1.34389 3
1 Discrepancies in the position of free gingival margin without recession 0.4397 1.39504 4
6 Discrepancies in the position of free gingival margin with recession −1.1729 1.19827 5
4 Varying degrees of inflammation of gingiva −1.4433 2.53064 6
5 Varying degrees of pigmented gingivae −2.5367 1.87122 7
2 Variations in the positions of interdental papilla (black triangles) −2.6000 1.78014 8

Rater reliability was judged by randomly repeating the control photograph twice so that it was rated twice by each layperson.

Table II describes the most unattractive and most attractive variations in a group or the intragroup rating. Factor 1 was alterations in the level of free gingival margin without recession. The variation shown in Figure 1 , N —free gingival margin of the central incisor reduced below the level of the lateral incisor unilaterally—was rated as the most unattractive, and the photograph with the free gingival margin of the canine, and lateral and central incisors at same level bilaterally was scored as the most attractive in this group ( Fig 1 , H ). The second factor was variations in the position of interdental papilla (black triangles). In this group, the variation with the 3-mm black triangle between the maxillary central incisors, lateral incisors, and canines ( Fig 2 , F ) was the most unattractive, and Figure 2 , B , with a 2-mm black triangle between the maxillary central incisors was rated as the most attractive. The third factor was the discrepancy in the position of the zenith. In this group, Figure 3 , G , the photo with the lateral zenith shifted mesially unilaterally was scored as the most unattractive, and the photograph with the lateral zenith shifted distally bilaterally was rated as the most attractive ( Fig 3 , C ). The fourth factor was varying degrees of inflammation of the gingiva. Papillary gingivitis ( Fig 4 , A ) was rated as the most unattractive, whereas generalized gingivitis ( Fig 4 , C ) was rated as the most positive. The fifth factor was varying degrees of pigmented gingiva. In Figure 5 , A , pigmentation in patches, was rated as the most unattractive, whereas Figure 5 , C , generalized pigmentation, was rated as the most attractive. The sixth factor was discrepancies in the position of the free gingival margin with the recession. The 3-mm generalized recession ( Fig 6 , O ) was rated as the most unattractive, and the 1-mm recession in the canines bilaterally ( Fig 6 , D ) was rated as the most attractive. The seventh factor was gingival contour and bilateral accentuated gingival contours ( Fig 7 , A ) that were ranked as the most unattractive and the bilateral denuded contour ( Fig 7 , B ) that was ranked as the most attractive. The last factor was the control group, and both control photographs were rated similarly.

Dec 10, 2018 | Posted by in Orthodontics | Comments Off on Impact of altered gingival characteristics on smile esthetics: Laypersons’ perspectives by Q sort methodology
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