Oral health in adolescents: periodontal inflammatory biomarkers during orthodontic clear aligner therapy

Abstract

Objectives: This prospective study aimed to evaluate periodontal inflammation in adolescents undergoing orthodontic treatment with clear aligners (Invisalign® Teen, Align Technology, San Jose, CA, USA). Key objectives included assessing the presence of 11 periodontitis-associated marker bacteria, active matrix metalloproteinase-8 concentrations in sulcular fluid, and the influence of IL-1 polymorphism genotypes on periodontal health.

Materials and methods: Fifty adolescent patients (13.3 ± 1.8 years) with mixed and permanent dentition participated. Gingival crevicular fluid samples were analyzed at multiple time points: before, during, and one year after aligner treatment. Periodontal health was assessed using the Gingivitis Index and the Modified Quigley-Hein Index. Genotypic analysis of IL-1 polymorphism was also performed. Statistical analyses included mixed linear models and generalized linear models to explore correlations.

Results: All combinations of IL-1 polymorphism genotypes were found in the sample. No significant increase in periodontal inflammation or aMMP-8 concentrations was observed over the treatment period. Marker bacteria from the red and orange-associated complexes remained at low levels, while significant changes occurred in the orange and green complexes, particularly Capnocytophaga spp. (p = 0.0042) and Fusobacterium spp. (p = 0.0365). GI correlated significantly with aMMP-8 levels (p = 0.0017), but no genotype effect on GI was observed. MQH showed associations with pathogens from the orange and green complexes, including Capnocytophaga spp. and Fusobacterium spp.

Conclusions: Clear aligner treatment in adolescents, including those with an unfavorable genotype, does not increase periodontal inflammation when accompanied by good oral hygiene.

Clinical relevance: Regular periodontal monitoring and hygiene reinforcement is important during orthodontic treatment, especially in adolescent patients.

Keywords: Aligner therapy; IL-1 polymorphism; Inflammatory biomarker; Matrix metalloproteinase-8; Orthodontics.

Fig. 1

a. An example of clear aligner use in the treatment of crowding. b. An example of the scalloped trimline design

Fig. 2

Example of periodontal pathogen examination with paper points in the mesial approximal space

Fig. 3

Example of sampling to determine the concentration of aMMP-8 with paper strips in the distal proximal space

Fig. 4

Boxplot distribution of gingival index as a function of upper jaw/lower jaw and visit

Fig. 5

Boxplot Distribution of MQH as a function of upper jaw/lower jaw and visit

Fig. 6

Frequency distribution of periodontitis marker bacteria complexes: (a + b) Frequency distribution of Fusobacterium spp. over time as an example of strong changes in the orange complex (a: maxilla, b: mandible); (c + d) Frequency distribution of Capnocytophaga spp. over time as an example of strong changes in the green complex (c: maxilla, d: mandible). The concentration of Fs and Cs is given as 0, ( +), + , + + , + + + representing no detection of the marker bacterium, low concentration, increased, strongly increased and very strongly in-creased levels respectively

Fig. 6

Frequency distribution of periodontitis marker bacteria complexes: (a + b) Frequency distribution of Fusobacterium spp. over time as an example of strong changes in the orange complex (a: maxilla, b: mandible); (c + d) Frequency distribution of Capnocytophaga spp. over time as an example of strong changes in the green complex (c: maxilla, d: mandible). The concentration of Fs and Cs is given as 0, ( +), + , + + , + + + representing no detection of the marker bacterium, low concentration, increased, strongly increased and very strongly in-creased levels respectively

Fig. 7

Boxplot of aMMP-8 concentrations [ng/ml] divided by genotype and by visits 1 to 8. The additional marker within the "box" represents the arithmetic mean. Values below ≤ 8 ng/ml (normal) indicate a very low risk of gingivitis), between 8 and 20 ng/ml (borderline) indicate low-grade local inflammation and ≥ 20 ng/ml (elevated) indicate acute inflammation [37]