This study aimed to associate 2 indexes for evaluating malocclusion in the mixed dentition.
A population-based cross-sectional study was conducted involving 743 children aged 8-10 years, divided into early and late mixed dentition. The Dental Aesthetic Index (DAI) and criteria proposed by Grabowski were used to evaluate malocclusion. Associations between the DAI (outcome variable) and the other independent variables (gender, race, and mixed dentition stage) were analyzed using logistic regression models. Simple logistic regression models were constructed, estimating the crude odds ratios with the respective 95% confidence intervals (CIs). The variables with P < 0.20 in the simple analyses were tested in multiple logistic regression models, estimating adjusted odds ratios with the respective 95% CIs.
We found that 84.01% (185/220) of the diagnoses were coincidental between the Grabowski Index and DAI in patients without malocclusion. In contrast, 59.80% (439/734) of the patients were diagnosed by both indexes (Grabowski and DAI) with malocclusion. Children with malocclusion, diagnosed by the Grabowski Index, were 5.85 ( P = 0.0001 and 95% CI: 4.08-8.39) times more likely to show malocclusions when diagnosed by the DAI.
DAI and the criteria proposed by Grabowski were expressed differently in relation to malocclusion in the mixed dentition. This study suggests the importance of specific criteria for the evaluation of malocclusion at this stage of development.
We compared the Dental Aesthetic Index and Grabowski Index for children in mixed dentition.
Diagnoses coincided with 60% and 85% of children with and without malocclusion, respectively.
The indexes were expressed differently in relation to malocclusion in the mixed dentition.
Specific indexes that determine orthodontic treatment need are essential in epidemiologic studies of malocclusion because they compare different age groups and populations. Because of difficulties in defining, quantifying, and relating malocclusion with oral health problems, there is increased interest in using numeral scales to score malocclusions objectively.
The occlusal index should identify patients not needing treatment and those in need of orthodontic treatment to allocate limited resources and identify the most effective orthodontic appliances; besides, this should be easy to use. , The main occlusal indexes were specially developed for primary and permanent dentition.
Mixed dentition is characterized by a wide range of occlusal variations, and the assessment of orthodontic treatment need should also consider this developmental stage. However, there is a lack of epidemiologic studies on the mixed dentition. The majority of the studies on this age range used the Dental Aesthetic Index (DAI), , Index of Orthodontic Treatment Need, , , , or the evaluation of the malocclusion proposed by Grabowski. ,
The DAI is an established epidemiologic occlusal index that has previously been used in different populations to determine the prevalence and orthodontic treatment need. However, the DAI was developed for patients with permanent dentition, and conditions such as the median diastema may overestimate the prevalence of malocclusion in mixed dentition. , In contrast, Grabowski et al proposed a method for evaluating malocclusions in primary and early mixed dentitions but did not determine orthodontic treatment need scores. The aspects of sagittal, transverse, and vertical occlusal relationships are considered.
This study aimed to associate 2 occlusal indexes, DAI and Grabowski, in the mixed dentition, and answer the following question: how should malocclusion in mixed dentition be evaluated? We hypothesized that the DAI overestimates the orthodontic treatment need.
Material and methods
This study received approval from the Human Research Ethics Committee of Brazil (CAAE no. 80184717.1.0000.5385). Parents/caregivers signed a statement of informed consent authorizing the participation of their children.
A population-based cross-sectional study was conducted involving children aged 8-10 years enrolled in public schools. All public schools (n = 11) with children in the target age range were included in the study, and conglomerates performed a probabilistic sampling. The distribution of 8- and 10-year-old children in each region of Araras (São Paulo, Brazil) was determined from information provided by the Municipal Secretary of Education. The sample was stratified according to the administrative district, and in the first phase, schools were randomly selected. In the second phase, children were selected for the sample using a simple randomization procedure. Classrooms were randomly selected at the schools, and children were randomly selected from those classes. The minimum sample of 650 patients was calculated based on a 5% significance level, 95% confidence interval (CI), a test power of 80%, and an effect size of 1.5. The minimum sample size was estimated at 650 schoolchildren. The inclusion criteria were aged between 8 and 10 years and mixed dentition. Children who had previously undergone orthodontic treatment or who had completed permanent dentition or systemic diseases such as cerebral palsy or Down syndrome were excluded. The final sample was 734 patients aged 8-10 years.
Clinical evaluations were made with the aid of a Community Periodontal Index probe recommended by the World Health Organization. Initially, the children were classified according to the mixed dentition stage. The mixed dentition was determined by having a reference dental age, as proposed by Van der Linden, and based exclusively on the teeth present in the buccal cavity. According to this referential, the mixed dentition presents 2 important periods of the exchange of deciduous teeth by permanent teeth: early (first transitional period) and late (second transitional period) mixed dentition. For the epidemiologic evaluation, early mixed dentition included only children with maxillary and mandibular permanent central and lateral incisors and completely erupted first molars, and the late-stage included children who presented with the other permanent teeth (maxillary and mandibular permanent canines, premolars, and second molars) in the process of eruption or completely erupted.
The clinical examination recorded aspects of occlusion by the DAI and Grabowski et al. The outcome variable of the study was the DAI. The independent variables were classified into demographic and clinical groups. The demographic variables were sex (female and male) and race (white and nonwhite). The clinical variables considered were the presence of malocclusion, as evaluated by the Grabowski Index, and the period of development of the mixed dentition (early mixed dentition and late mixed dentition). Early mixed dentition considered only children with all permanent incisors erupted.
The DAI mathematically relates to the subject’s perception of dental aesthetics with occlusal characteristics associated with malocclusion. It includes parameters of dentofacial anomalies related to the following clinical and aesthetic aspects: the number of visibly absent teeth, anterior crowding, anterior spacing, midline diastema, maxillary anterior misalignment, maxillary anterior horizontal overlap, mandibular anterior horizontal overlap, anterior open bite, anteroposterior molar relation, and posterior crossbite. The DAI Index score is analyzed using the sum of scores of each characteristic evaluated added to a constant value. This sum leads to a classification that identifies the orthodontic treatment need of patients as determined by the severity of the occlusal pathologies present: grade 1 indicates the absence of malocclusion and orthodontic treatment need (DAI ≤25), grade 2 indicates malocclusion is defined and elective orthodontic treatment is needed (DAI = 26 to 30), grade 3 indicates severe malocclusion and a desirable orthodontic treatment need (DAI = 31 and 35), and grade 4 indicates severe malocclusion and a mandatory orthodontic treatment need (DAI ≥36). For data analysis, the DAI was dichotomized into the absence (grade 1) and presence (grade 2, 3, and 4) of malocclusion.
The Grabowski Index evaluates occlusal characteristics from the sagittal relationship in the anterior and posterior regions, the transverse relationship in the posterior region, and the transverse relationship in the anterior region. The measurement (in millimeters) was performed with the teeth in centric occlusion, and the probe was positioned parallel to the occlusal plane. No distance between maxillary and mandibular incisors was defined as normal overjet (0 mm). Increased overjet was recorded when the distance was >2 mm, and the anterior crossbite was recorded when the distance was <0 mm. An anterior crossbite was recorded when the mandibular incisors were observed in front of the maxillary incisors. An anterior open bite was recorded in the absence of contact between the anterior teeth when the posterior teeth were in occlusion. A normal overbite was defined when the maxillary incisors overlapped the mandibular incisors by 2 mm. An overbite greater than 2 mm was designated a deep overbite. A posterior crossbite was recorded when maxillary primary molars were occluded in a lingual relationship to the mandibular primary molars in a centric occlusion. The children were diagnosed with malocclusion when exhibiting at least 1 of the aforementioned conditions. The data were dichotomized into the absence and presence of malocclusion.
The examinations were performed under artificial light in schools by a single trained and calibrated examiner (A.L.M.C.). Before the examiner started the experimental phase, a 16-hour training was performed, including 4 hours of theoretical classes and 12 hours of practical classes. Another 4 hours were dedicated to the calibration process to obtain an estimate of the diagnostic extension. The intraexaminer agreement was estimated by the intraclass correlation coefficient for the DAI and Grabowski Index components, with an acceptable limit value greater than 0.92.
Initially, descriptive analyzes of the data were performed. The associations between the malocclusion by DAI Index (outcome variable) and the other variables, gender (female/male), race (white/nonwhite), mixed dentition stage (early/late), and malocclusion according to Grabowski Index (absence/presence), were analyzed using logistic regression models. Odds ratios were estimated with the respective 95% CIs. The analyses were performed in the R Program (R Foundation for Statistical Computing, Vienna, Austria) with a 5% significance level.
The final sample was composed of 734 boys (51.77%) and girls (48.23%) aged 8 to 10 years (mean, 9.1 years), white (61.85%), and nonwhite (38.15%). Most of the children were in the late mixed dentition stage (63.08%). Malocclusion was present in 70.03% and 74.79% of children according to the Grabowski Index and DAI Index, respectively ( Table I ).
|Mixed dentition stage|
|Malocclusion Grabowski Index ∗|
|Malocclusion DAI †|