1 Volume 24 2025 e255145 Original Research Braz J Oral Sci. 2025;24:e255145http://dx.doi.org/10.20396/bjos.v24i00.8675145 1 Department of Health Sciences and Pediatric Dentistry, Community Dentistry Division, Faculdade de Odontologia de Piracicaba, Universidade Estadual de Campinas (UNICAMP), Piracicaba, Brazil. 2 Araras Dental School, Hermínio Ometto Foundation (FHO), Araras, SP, Brazil. Corresponding author: Diego Patrik Alves Carneiro Limeira Avenue, 901 - Areiao, Piracicaba, SP - Brazil. 13414-903 +55 19 98214-2834 e-mail: diegopatrikmoa@gmail.com Editor: Dr. Altair A. Del Bel Cury Received: December 04, 2023 Accepted: March 17, 2024 Association of malocclusions in the smile zone and periodontal disease Diego Patrik Alves Carneiro1* , Kaarlye Cantarelli Pires Andrade de Melo2 , Marcelo de Castro Meneghim1 , Silvia Amélia Scudeler Vedovello1 Aim: This epidemiological study evaluated the association of malocclusions in the smile zone and periodontal disease. Methods: A population-based cross-sectional study was conducted with 700 adolescents aged 15 to 19. The occlusal conditions assessed were overjet, overbite, mandibular crowding, and spacing. Periodontal Screening and Recording (PSR) determined the presence of periodontal disease. The variables were analyzed using a simple logistic regression model, estimating raw odds ratios. Variables with P<0.20 in simple analyses were tested in multiple regression models. Only the variables with P≤0.05 remained in the final adjusted model after adjusting for the other model variables. Estimating adjusted odds ratios with the respective 95% confidence intervals. Results: Periodontal disease was significantly associated with crowding in the anteroposterior region (OR= 1.97; 95% CI: 1.08-3.59), as well as with the presence of open bite (OR= 4.11; 95% CI: 1.57-10.76). Conclusions: Malocclusions in the smile’s esthetic zone are associated with periodontal disease. Mandibular crowding and anterior open bite increase the risk of periodontal disease. Keywords: Malocclusion. Periodontal diseases. Periodontal Index. https://orcid.org/0000-0001-7864-3055 https://orcid.org/0009-0002-6661-4673 https://orcid.org/0000-0003-2673-3627 https://orcid.org/0000-0002-7203-2867 2 Carneiro et al. Braz J Oral Sci. 2025;24:e255145 Introduction The development and progression of periodontal disease are associated with differ- ent risk factors. Understanding how such factors change plays an essential role in the treatment and management of individuals1. In this context, tooth misalignment is one of the main factors contributing to periodontal disease development2-5. The mechanism by which malocclusion can affect periodontal health is intuitive since the disarrangement of the correct positioning of the teeth has an unfavorable environ- ment for maintaining periodontal health. The malocclusion promotes the retention of food residues and the constant accumulation of bacterial plaque and, consequently, its mechanical removal is difficult1,5-7. The optimization of dentofacial aesthetics is one of the main reasons for seeking orthodontic treatment; thus, individuals expect to improve facial contour, appearance, and self-esteem since occlusal disorders located in anterior regions play an essential role in the impact of well-being. -social and emotional well-being of these individu- als8,9. Occlusal conditions such as mandibular crowding, increased overjet, and cross- bite seems to be associated with periodontal disease8,10. The results of studies that investigated this association were controversial. Conflicts of information can be justified by combining indices to evaluate periodontal disease and crowding without isolating the characteristics. Furthermore, we highlight the diffi- culty in differentiating crowding from misalignment, which can cause statistical vari- ability caused by a small sample size. Even with ideal oral hygiene control, when teeth are inadequately positioned, especially in the mandibular arch, this is associated with difficulty in removing bacterial plaque and, consequently, gingival inflammation and periodontal problems6,8,11,12. The present study aims to answer the following question: What is the relation- ship between occlusal conditions and adolescent periodontal disease? The study hypothesis is that the malocclusions in the smile region are associated with periodontal disease. Methods The study was approved by the Human Research Ethics Committee (#82365917.8.0000.5385). The consent of parents and/or guardians was obtained before data collection, and the assent of underage participants. A population-based cross-sectional study was carried out involving adolescents enrolled in public schools in a municipality in northeastern Brazil with an esti- mated population of 86,350 inhabitants and a human development index of 0.661. A representative sample of adolescents aged 15 to 19 enrolled in all pub- lic schools in the city was selected. Initially, a complex stratified sampling was conducted at two levels: schools by neighborhoods and students by school. The minimum sample size of 560 participants was calculated using the G*Power Pro- gram (G*Power: Statistical Power Analysis, Düsseldorf, Germany), considering a confidence interval (CI) of 95%, a test power of 80%, and an effect size of 1.5. 3 Carneiro et al. Braz J Oral Sci. 2025;24:e255145 The sample was increased by 20% to compensate for possible dropouts. Only adolescents with complete permanent dentition were included in the study. Ado- lescents who underwent previous or current orthodontic treatment and those with an apparent mental and/or physical disability that could influence the results of the oral examination were excluded from the study. The final sample comprised 700 adolescents. Malocclusion was assessed epidemiologically using a WHO probe using the Dental Aesthetics Index (DAI)9,12-16. The DAI is a numerical index designed to assess specific occlusal characteristics and includes parameters of dentofacial anomalies related to clinical and aesthetic aspects. The present study used the occlusion assessment parameters defined by the index: overjet, overbite, mandibular crowding, and spacing. For data analysis, the variables were divided into standard, increased, and decreased overjet (or anterior crossbite), mandibular crowding, and spacing13. Overjet was measured in millimeters, considering the distance between the buc- cal incisor of the most protruding upper incisor and the buccal surface of the cor- responding lower incisor. The values considered were ≥ 3 mm = normal overjet, ≤ 0 mm = decreased overjet and > 4 mm = increased overjet. Overbite was measured in millimeters, considering the distance between the incisal edges of the anterior teeth. The values considered were ≥ 3 mm = normal overbite, ≤ 0 mm = anterior open bite and > 4 mm = deep bite. Mandibular crowding included the four lower permanent incisors. Crowding was considered when the space between the right and left lower canines was insufficient to accommodate the four incisors in alignment and was clas- sified as no mandibular crowding and with mandibular crowding. Anterior spacing was considered when the space between the right and left canines was greater than necessary for the normal alignment of the incisors. Spacing in the anterior segment was classified as no spacing, spacing in at least one dental arch, and spacing on the maxillary and mandibular arches9,12-16. Periodontal Screening and Recording (PSR) determined the periodontal conditions using a WHO 621 probe (Golgran, São Caetano do Sul, SP)17. The following param- eters were considered: 0, periodontal health without visible bleeding; 1, periodontal health with bleeding after probing; 2, periodontal health with bleeding and presence of retentive factors; 3, presence of a shallow pocket of 4 to 5 mm; 4, presence of a deep pocket ≥ 6 mm17. For the present study, periodontal problems were dichotomized: 0 – 2, with no periodontal disease; 3 – 4, with periodontal disease. Calibration A single examiner, previously trained and calibrated, performed the oral examinations. The calibration consisted of a theoretical discussion followed by a practical calibra- tion. The training in question resulted in an intraclass correlation coefficient greater than 0.92, indicating satisfactory inter- and intra-examiner agreement. Statistical Analysis A contingency table was constructed between each independent variable and the study outcome (periodontal disease). Logistic regression models were adjusted 4 Carneiro et al. Braz J Oral Sci. 2025;24:e255145 between each independent variable and the outcome. Variables that showed P<0.20 in these individual analyses were studied in a multiple logistic regression model. Only the variables with P≤0.05 remained in the final adjusted model after adjusting for the other model variables. Based on the coefficients of the regression models, crude, and adjusted odds ratios with 95% confidence intervals were esti- mated. Model fit was assessed using the Akaike Information Criterion (AIC). All anal- yses were performed using the R program (R Foundation for Statistical Computing, Vienna, Austria), with a significance level of 5%. Results The final sample comprised 700 adolescents aged 15 to 19, 53.9% female (n= 377) and 46.1% male (n= 323). The descriptive data of the sample is shown in Table 1. Table 1. Descriptive data of the evaluated variables. Variable Category n (%) Global - 700 (100.0%) Age range ≤ 16 years 489 (69.9%) > 16 years 211 (30.1%) Sex Male 323 (46.1%) Female 377 (53.9%) Mandibular crowding Absence 493 (70.4%) Presence 207 (29.6%) Spacing Absence 572 (81.7%) Presence 128 (18.3%) Maxillary overjet Absence 697 (99,6%) Presence 3 (0.4%) Anterior open bite Absence 670 (95.7%) Presence 30 (4.3%) Anterior crossbite Absence 696 (99.4%) Presence 4 (0.6%) Table 2 presents the crude and adjusted analyses of the associations between mal- occlusion and periodontal disease. The results showed that periodontal disease was significantly associated with mandibular crowding (OR= 1.97; 95% CI: 1.08-3.59) and anterior open bite (OR= 4.11; 95% CI: 1.57-10.76). 5 Carneiro et al. Braz J Oral Sci. 2025;24:e255145 Table 2. Analyzes (crude and adjusted) of associations with the presence of periodontal disease. Variable Category Periodontal disease OR crude (CI95%) p-value OR adjusted (CI95%) p-valueAbsence *Presence n (%) n (%) Global - 650 (92.9%) 50 (7.1%) - - - - Age range ≤ 16 years 459 (93.9%) 30 (6.1%) 1 - - > 16 years 191 (90.5%) 20 (9.5%) 1.60 (0.89-2.89) 0.1177      Sex Male 297 (92.0%) 26 (8.0%) 1.29 (0.72-2.29) 0.3896 - - Female 353 (93.6%) 24 (6.4%) 1        Mandibular crowding Absence 464 (94.1%) 29 (5.9%) 1 1 Presence 186 (89.9%) 21 (10.1%)  1.81 (1.01-3.25) 0.0482   1.97 (1.08-3.59) 0.0260  Spacing Absence 531 (92.8%) 41 (7.2%) 1 - - Presence 119 (93.0%) 9 (7.0%)  0.98 (0.46-2.07) 0.9570      Overjet Absence 648 (93.0%) 49 (7.0%) 1 - - Presence 2 (66.7%) 1 (33.3%)  6.61 (0.59-74.21)  0.1257     Anterior open bite Absence 626 (93.4%) 44 (6.6%) 1 1 Presence 24 (80.0%) 6 (20.0%) 3.56 (1.38-9.16)  0.0085  4.11 (1.57-10.76)  0.0040  Anterior crossbite Absence 646 (92.8%) 50 (7.2%) - - - Presence 4 (100.0%) 0 (0.0%)         *Outcome. 1: Reference category for independent variables. OR: Odds ratio. CI: Confidence interval. AIC (empty model)=362.25; AIC (final model)=355.92. Discussion The association between malocclusion and periodontal disease awakens interest in the literature. However, the need for standardization of evaluation methods is evi- dent, which compromises comparisons and influences results1,6,11,18. Thus, the pres- ent study answered the question: What is the relationship between occlusal condi- tions and adolescent periodontal disease? The study hypothesis was accepted. Our results showed that mandibular crowding and anterior open bite affect adolescent periodontal conditions. Periodontal disease presents different layers of clinical manifestations, from gingi- val inflammation to the most severe cases leading to tooth loss19-21, and age plays a crucial role in this context. Adolescents are commonly affected by milder forms of the disease, although the more severe periodontal disease is less common, and the inflammatory changes associated with periodontal disease occur during this period21,22. 6 Carneiro et al. Braz J Oral Sci. 2025;24:e255145 Several diagnostic methods have been used in epidemiological studies to assess periodontal disease, ranging from detecting retentive factors to identifying bone loss through radiographic examinations8. However, the different methods prevent comparison between studies8,21. To assess occlusal conditions in the context of a population-based study, we chose to adopt the DAI index criteria. Although we did not use all of its components, the evaluation criteria were clearly and precisely used. Therefore, in the present study, we sought not only to standardize the instruments used to assess these two variables but also to ensure that the assessment was carried out by a single, duly trained, and calibrated evaluator. In addition, it is essen- tial to highlight that one of the study’s strengths is that it used a homogeneous and representative sample of adolescents. Our findings showed that mandibular crowding was associated with periodontal dis- ease in adolescents. The results are in line with the literature, which highlights that periodontal problems, especially gingival bleeding, are associated with lower anterior teeth, suggesting that crowding and the presence of retentive factors may contribute to this association1,8,21,23. The anterior open bite was also associated with the presence of periodontal disease. A previous study observed that an anterior open bite favored the accumulation of bacterial plaque, gingival inflammation, and increased clinical probing depth24. The absence of anterior vertical contact, a condition that characterizes an open bite, makes it difficult to adequately clean the area, mainly if other associated conditions, such as inadequate dental positions, are commonly found24. Thus, despite the aes- thetic and functional impact, anterior open bite influences the health of periodontal tissues and deserves prominence. Mandibular crowding was the most prevalent condition in the studied population, followed by spacing and anterior open bite. However, only mandibular crowding and anterior open bite were associated with periodontal disease. Concerning the litera- ture, the subject of discussion is the relationship between the presence of maxillary overjet, anterior crossbite, and spacing with the presence of periodontal disease. A study conducted by Bernhardt et al.8 showed that these conditions are more strongly linked to severe periodontal problems, including gingival trauma, which can accentuate the occurrence of gingival recessions and, consequently, attachment loss. In addition, it is worth mentioning that the frequency of these conditions in our sample population was low. As a population-based epidemiological study, this study did not collect participant model records. This limitation restricted the capacity to categorize the sample into subgroups. Consequently, future studies are encouraged to establish cutoff points for dental crowding and conduct a more in-depth examination of this asso- ciation. Finally, our findings highlight the importance of the professional’s correct guidance regarding the influence of these malocclusions on the onset and/or pro- gression of periodontal disease. Periodontal-orthodontic treatment is frequently included in adult patients with periodontal disease due to impaired smile esthetics, functional problems, or adjunctive treatment before prosthetic rehabilitation. Our findings suggest that the adolescent patient should be evaluated with the same 7 Carneiro et al. Braz J Oral Sci. 2025;24:e255145 care since the orthodontic treatment provides occlusal balance and improves periodontal conditions. In conclusion, malocclusions in the smile’s esthetic zone are associated with peri- odontal disease. Mandibular crowding and anterior open bite increase the risk of periodontal disease. Periodontal–orthodontic treatment could be included in the fol- low-up of the adolescent patient. Conflict of Interest The authors have no conflict of interest to disclose. Data Availability Datasets related to this article will be available to the corresponding author upon request. 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