Introduction
In this study, we aimed to assess the effect of the duration of fixed orthodontic treatment on gingival enlargement (GE) in adolescents and young adults.
Methods
The sample consisted of 260 subjects (ages, 10-30 years) divided into 4 groups: patients with no fixed orthodontic appliances (G0) and patients undergoing orthodontic treatment for 1 year (G1), 2 years (G2), or 3 years (G3). Participants completed a structured questionnaire on sociodemographic characteristics and oral hygiene habits. Clinical examinations were conducted by a calibrated examiner and included the plaque index, the gingival index, and the Seymour index. Poisson regression models were used to assess the association between group and GE.
Results
We observed increasing means of plaque, gingivitis, and GE in G0, G1, and G2. No significant differences were observed between G2 and G3. Adjusted Poisson regression analysis showed that patients undergoing orthodontic treatment had a 20 to 28-fold increased risk for GE than did those without orthodontic appliances (G1, rate ratio [RR] = 20.2, 95% CI = 9.0-45.3; G2, RR = 27.0, 95% CI = 12.1-60.3; G3 = 28.1; 95% CI = 12.6-62.5).
Conclusions
The duration of orthodontic treatment significantly influenced the occurrence of GE. Oral hygiene instructions and motivational activities should target adolescents and young adults undergoing orthodontic treatment.
Highlights
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Duration of fixed orthodontic treatment affected anterior tooth gingival enlargement.
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Longer treatment was related to more plaque, gingivitis, and gingival enlargement.
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Motivational activities should target adolescent and young adult patients.
The effect of fixed orthodontic appliances on periodontal parameters has been shown previously. In general, favorable conditions for plaque stagnation as well as difficulty in performing usual oral hygiene measures have been associated with poorer periodontal health among orthodontic patients. Nevertheless, some studies have suggested that gingival changes during the use of fixed orthodontic appliances do not cause permanent aggression to periodontal support tissues.
Gingival enlargement (GE) is excessive growth of the gums where the inflammatory tissue may be in a limited region, or it may be generalized. The mechanism by which it occurs during orthodontic treatment is not fully understood, wherein artificially deep periodontal pockets are established. Few studies have assessed the occurrence of GE during orthodontic treatment. In 2014, Eid et al and Zanatta et al found a positive association between the use of fixed orthodontic appliances and gingivitis and GE. However, neither study had a control group (without brackets), and they combined in the same category orthodontic patients undergoing treatment for 12 months or more and for 18 months or more. Thus, the effect of longer periods of orthodontic treatment was not studied.
A previous study showed that anterior GE promotes a negative impact on oral health-related quality of life of orthodontic patients, thus emphasizing the need for further investigations on this issue. Therefore, in this study, we aimed to assess the effect of the duration of fixed orthodontic treatment on GE in adolescents and young adults.
Material and methods
In this cross-sectional study, we selected participants who sought or were undergoing fixed orthodontic treatment in an orthodontic graduate program in Santa Maria, Rio Grande do Sul, Brazil. The study protocol was approved by the ethics committee of the Federal University of Santa Maria (number 0109/2013). Patients or their legal guardians were informed about the study objectives and authorized their participation by signing a written informed consent form.
The required number of subjects was estimated based on an expected difference among groups of 20%. Considering a power of 80% and a confidence interval of 95%, 65 persons per group were required. The sample was stratified into 4 groups according to the duration of fixed orthodontic treatment: G0 (control), including candidates for corrective orthodontic treatment, examined previously for fixed appliances; G1, composed of patients undergoing fixed orthodontic treatment for 1 year (10-14 months); G2, composed of patients undergoing fixed orthodontic treatment for 2 years (22-26 months); and G3, composed of patients undergoing fixed orthodontic treatment for 3 years (34-38 months).
Patients aged 10 to 30 years were considered eligible for this study. To be included in G1, G2, and G3, participants should be using fixed orthodontic appliances for a specific period of time, as previously described. Fixed corrective orthodontic treatment was carried out with conventional metal brackets, straight wire technique, orthodontic arches fixed with simple elastic bandages, and without metal ligatures, elastic chains, or proximal enamel stripping. Orthodontic rings (bands) were adapted to the molars with glass ionomer cement. Initially, orthodontic movement of alignment and leveling were performed to correct the horizontal and vertical discrepancies with subsequent space closure, when necessary, and finishing that included compensatory folds in the arches, such as torque, intrusion, and extrusion. Patients in need of traction of impacted teeth and wide repositioning of teeth lingually or buccally (>2 mm) were not included in the sample. To be included in group 0, subjects should not be using or have previously used fixed orthodontic appliances. Patients suffering from congenital abnormality, systemic illness, cysts, or crevices, or with special needs or using systemic medication for the treatment of chronic diseases that might interfere with gingival overgrowth were excluded from the sample. Patients who required chemoprophylaxis before clinical examination were also excluded.
Initially, the subjects answered a structured questionnaire on sociodemographic characteristics and oral hygiene habits. Clinical examinations were performed in a dental unit, using a dental mirror, a periodontal probe type Williams (Golgran, São Caetano do Sul, Brazil), and a World Health Organization probe.
Clinical examination included assessment of the plaque index of Löe and Silness, evaluation of the gingival index of Löe, professional prophylaxis with sodium bicarbonate spray (Jet Laxis Uno; Schuster, Santa Maria, Brazil), tooth drying with air-water syringe, relative isolation with cotton rolls, assessment of the excess composite resin at the cervical side of the brackets, where 0 was considered absent and 1 present, adapted from the study of Zanatta et al, and assessment of the Seymour index to record the occurrence of GE in the anterior segment by visual inspection. Buccal and lingual papillae of the 6 anterior teeth, maxillary and mandibular, were examined. Gingival thickening and gingival encroachment onto adjacent crowns were graded. The sum of both scores (thickening and encroachment) resulted in an enlargement score for each gingival unit. The maximum score with this method was 5, and the sum of all papillae provided 1 score per patient (range, 0-100). These indexes are described in Table I .
| Plaque index | |
| 0 | Surface without plaque |
| 1 | Plaque at the gingival margin and the tooth, visible only after probe use |
| 2 | Moderate accumulation of plaque at the gingival margin and the tooth, visible to the naked eye |
| 3 | Abundant accumulation of plaque at the gingival margin and the tooth |
| Gingival index | |
| 0 | Normal gums |
| 1 | Mild inflammation, with a slight change in color and slight swelling but no bleeding on probing |
| 2 | Moderate inflammation with redness, swelling, and bleeding on probing |
| 3 | Severe inflammation with redness and severe edema, tending to ulceration and spontaneous bleeding |
| Seymour index | |
| Gingival thickening | |
| 0 | Normal |
| 1 | Thickening ≤2 mm |
| 2 | Thickening >2 mm |
| Gingival encroachment | |
| 0 | Normal |
| 1 | Papilla involving 1/3 of adjacent tooth crown half |
| 2 | Papilla involving 2/3 of adjacent tooth crown half |
| 3 | Papilla involving >2/3 of adjacent tooth crown half |
One examiner (A.S.P.) performed the clinical examinations. Training sessions were performed to ensure examiner reliability in regard to the indexes. Repeated examinations were performed in 16 subjects (6%), and a kappa value of 0.95 was obtained for the Seymour index. Since plaque accumulation and gingival bleeding are variable conditions, examiner calibration was not assessed for these indexes.
Statistical analysis
The main outcome of this study was anterior GE. The prevalence of anterior GE was defined as the proportion of subjects with a Seymour index value of 30 or greater based on the cutoff proposed by the index for the definition of clinically relevant GE. Additionally, the Seymour index was also treated as a counting variable and referred to in the manuscript as the extent of GE.
The subjects were classified into 3 categories for age: less than 15 years, 15 to 20 years, and older than 20 years. Mother’s education was classified as primary school, high school, or university. Family income was classified in 3 or fewer and greater than 3 Brazilian minimum wages (1 Brazilian minimum wage corresponded to about $295 US during the period of data collection). Toothbrushing frequency was dichotomized into 2 times or fewer per day and 3 times or more per day. The use of dental floss was classified as no use, not daily use, and daily use. The excess composite resin on all assessed surfaces was summed, and an overall score per patient was obtained, ranging from 0 to 12. The plaque index and the gingival index were calculated as the mean score of all assessed sites.
The chi-square test was used to compare G0, G1, G2, and G3 according to age, sex, mother’s education, toothbrushing frequency, and use of dental floss. The plaque index, gingival index, and Seymour index were compared among the groups with the Wald test. The relationship between the presence or absence of clinically relevant GE and groups was assessed using the Fischer exact test.
Poisson regression analysis with robust variance (unadjusted and adjusted models) was used to assess the association between group and extent of GE. Estimates were adjusted for sociodemographic characteristics, self-reported oral hygiene habits, and clinical variables (plaque index, gingival index, and excess composite resin). All variables were maintained in the adjusted model irrespective of their P values.
Data analysis was performed using software (version 11.1 for Windows; StataCorp, College Station, Tex). The significance level was set at 5%.
Results
A total of 260 subjects were included in the study (n = 65 per group). About 5% of the sample (n = 14) had incomplete permanent dentition, aged from 10 to 16 years. The number of absent teeth ranged from 1 to 5; they were most commonly second molars and maxillary canines.
Table II shows the sample distribution according to group, sociodemographic characteristics, and oral hygiene habits. There was no difference among groups in regard to sex, mother’s education, and toothbrushing. The proportion of patients undergoing orthodontic treatment for 3 years (G3) was reduced in the age category 15 years or less ( P = 0.03). The number of subjects receiving 3 or fewer Brazilian minimum wages and the use of dental floss decreased as the duration of orthodontic treatment increased ( P = 0.004 and P = 0.04, respectively).
| G0 | G1 | G2 | G3 | Total | P † | |
|---|---|---|---|---|---|---|
| Age (y) | 0.03 | |||||
| ≤15 | 17 | 21 | 20 | 7 | 65 | |
| 15-20 | 26 | 18 | 23 | 35 | 102 | |
| >20 | 22 | 26 | 22 | 23 | 93 | |
| Sex | 0.78 | |||||
| Male | 28 | 29 | 25 | 24 | 106 | |
| Female | 37 | 36 | 40 | 41 | 154 | |
| Mother’s education ∗ | 0.15 | |||||
| Primary school | 29 | 22 | 24 | 13 | 88 | |
| High school | 19 | 20 | 20 | 25 | 84 | |
| University | 17 | 22 | 21 | 27 | 87 | |
| Family income | 0.004 | |||||
| ≤3 BMW | 47 | 41 | 29 | 31 | 148 | |
| >3 BMW | 18 | 24 | 36 | 34 | 112 | |
| Toothbrushing | 0.37 | |||||
| ≤2 times/day | 20 | 19 | 27 | 19 | 85 | |
| ≥3 times/day | 45 | 46 | 38 | 46 | 175 | |
| Dental flossing ∗ | 0.04 | |||||
| No | 17 | 11 | 16 | 24 | 68 | |
| Not daily | 27 | 30 | 35 | 30 | 122 | |
| Daily | 21 | 24 | 13 | 11 | 69 | |
| Total | 65 | 65 | 65 | 65 | 260 |
Table III shows the plaque, gingival, and Seymour indexes according to the duration of orthodontic treatment. We observed increasing means from G0 to G1 and G2. No significant difference was observed between G2 and G3. The presence of clinically relevant GE was significantly associated with the duration of orthodontic treatment ( Table IV ).
| Plaque index | Gingival index | Seymour index | |
|---|---|---|---|
| G0 | 0.18 (0.14) a | 0.18 (0.14) a | 0.81 (2.66) a |
| G1 | 0.31 (0.18) b | 0.34 (0.22) b | 18.71 (12.83) b |
| G2 | 0.50 (0.28) c | 0.50 (0.27) c | 26.51 (12.51) c |
| G3 | 0.56 (0.25) c | 0.54 (0.26) c | 28.73 (11.17) c |
| Clinically relevant gingival enlargement | |||
|---|---|---|---|
| Absent | Present | P ∗ | |
| G0 | 65 | 0 | <0.001 |
| G1 | 49 | 16 | |
| G2 | 37 | 28 | |
| G3 | 36 | 29 | |
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