2020, Number 1
Evolution of anterior open bite treatment in patients in mixed dentition
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ABSTRACT
Introduction: Anterior open bite is considered a complex malocclusion, in which achieving and consolidating a vertical overbite represent a challenge for dentists and patients. It is predominantly associated with parafunctions such as digital sucking and atypical swallowing. Currently, there are various therapies available, including the use of the fixed palatal grid, which acts by preventing the habit, guiding the tongue, lips and masticatory musculature to orthofunction. Objective: To determine the amount of vertical overbite obtained in patients with anterior open bite, wearing a palatal grid. Material and methods: The study was observational, prospective, longitudinal and descriptive; in a group of patients aged five to 11 years, from the undergraduate area of the Faculty of Dentistry, UADY. The patients were diagnosed with anterior open bite, and treated over a period of 17 to 28 weeks with a palatal grid. Measurements were taken with an electronic vernier, in four sessions during treatment, with photographic evidence. The distance between two points was measured: the border between lower centrals and the border between upper incisors. The sample consisted of 47 patients, 23 males and 24 females. The database was created with Excel; the data was analysed with SPSS software using Student's t-test. Results: A critical value of -18.620 and a p-value of < 0.001 confirmed that evolution was significant. Conclusion: The orthodontic management should be complemented with psychological therapy and a phonoaudiologist for last-longer results and avoid relapses.INTRODUCTION
Skeletal malocclusions represent a complex health problem, as they involve anatomical disharmonies between the maxillae and the cranial base. All skeletal malocclusions include imbalances in the position of the dental organs, however, dental malocclusions exclude the bony component.1 The environmental influences acting during growth and development of the face, maxillae and dental organs consist primarily of pressures and forces that emerge from physiological activity of these components.1-3
During the development of the oral and masticatory functions of the stomatognathic system in infants, two swallowing patterns related to the type of feeding are observed, which in the long term may determine the position of the tongue during the swallowing act; the first is the infant swallowing pattern, which occurs from birth until the eruption of the primary dental organs.4 The second pattern correlates with later infant ages and is known as the adult swallowing pattern, which appears with the eruption of the first primary teeth at an average of 6-8 months of age. The tongue will gradually and steadily adopt a new position in the mouth, thus remaining contained in the oral cavity, and will persist for the rest of life.4-6 A third type of tongue position is observed during phonation, an act in which, in order to pronounce various locutions properly, the tongue must be placed behind the upper dental organs, but the infant who has atypical swallowing, interposes it between the upper and lower incisors.7 Anterior open bite is considered one of the most frequent malocclusions in paediatric populations. Depending on the location in the oral cavity where the anomaly manifests itself, the bite is classified as anterior open bite or simple open bite. The aetiology of open bite is multifactorial, involving environmental and genetic factors.8
MATERIAL AND METHODS
The anterior open bite was measured with an electronic vernier caliper. Two intraoral points were considered, the border between lower central teeth and the border between upper incisors, as well as the presence or absence of any parafunctional habit. Once the diagnosis was confirmed, at the start of treatment with the fixed palatal grid and the letter of informed consent was given, the first measurement was taken with a vernier calibrated in millimetres, which was taken as the first appointment. The second appointment was made between three and four weeks after the appliance was cemented (first appointment), and it was verified that the appliance was in good condition. Subsequent measurements were then taken until a minimum of four measurements per patient were obtained with intervals of three to four weeks between each of the four measurements. For statistical purposes, the initial measurement and the last recording were taken into account when the anterior open bite correction was achieved.
RESULTS
The sample consisted of 47 individuals, 51.1% (n = 24) female and 48.9% (n = 23) male. The age range was five to 11 years.
On average, 3.76 weeks elapsed with an average correction of 0.922 mm of vertical overbite, which means that on average 0.255 mm of open bite closure was achieved per week (Table 1).
In the interval from the 2nd to the 3rd measurement, the mean elapsed time was 5.89 weeks with 1.50 mm of vertical overbite, and on average 0.270 mm of closure was achieved per week. The highest degree of anterior open bite closure was recorded in this time interval (Table 2).
During the interval between the 3rd and 4th measurement, the mean elapsed time was 8.170 weeks, 0.908 mm closure and an average of 0.111 mm closure per week. The lowest average open bite closure rates were recorded in this period (Table 3).
In the time interval from the 1st to the 2nd measurement, 61.70% had an evolution between 0.4 to 0.95 mm, the minimum range of vertical overbite evolution. Between the 2nd and 3rd measurements, the greatest progress was recorded as 31.91% of the sample reported an evolution of between 1.85 to 2.75 mm. From the 3rd to the 4th appointment, it was observed that the majority, 61.70% of the participants, achieved an evolution of between 0.4 to 0.95 mm, this being the minimum range of evolution (Tables 1, 2 and 3).
To determine the degree of closure by sex, the female patients who achieved a greater progression of between 4.00 to 5.1 mm were plotted. As well as in the progression range of 2.90 to 4.00 mm, compared to the male sex (Figure 1).
The degree of advancement was determined according to age, where the age group with the highest degree of advancement was eight years old, followed by seven years old (Figure 2).
The degree of closure according to parafunctional habit determined that patients with digital suction and atypical swallowing had a better response to the appliance, since the highest degrees of closure (from 4.00 to 5.15 mm) corresponded to participants diagnosed with these parafunctions (Figure 3).
The data were analysed according to Student's t-test for two paired samples, where the null hypothesis (H0) states that both have equal means and the alternative hypothesis (Ha) states that the first sample (initial measurement) is smaller than the second (final measurement), taking into account the negative values recorded due to the negative vertical overbite. The results yielded a critical value of -18.620 and a p-value (significance) of < 0.001, which is sufficient evidence to reject the equality of means and consider the alternative hypothesis.
DISCUSSION
The aim of this research was to determine the evolution of anterior open bite closure in a group of patients in the mixed dentition. Research identified that digital sucking prevailed in 14%, atypical swallowing (or protractile tongue as reported by Gonzalez et al. in 2012) with 18.2%, oral breathing scored 10.8% and equally similar to the data found in our sample, 3.5% for lip sucking habit.8 In the literature it is discussed that the female population is mostly affected by anterior open bite; for example, Hernandez et al. has reported open bites in patients aged nine to 14 years, with a 65% frequency in this population.9,10 They also observed a decrease in the prevalence of this malocclusion with increasing age, a higher incidence in whites, a 70% incidence of lingual protrusion, followed by mouth breathing with 43.3% and finally digital sucking with 23.3%.11 The research carried out reported a higher incidence in the seven to nine year age groups, and a decrease in frequency was observed and documented in the 10 and 11 year age group, the maximum ages included in the sample.8
Villavicencio and Hernandez reported in a retrospective study, the effectiveness of the palatal grid to treat digital sucking in a sample of 75 patients aged 4 to 10 years. Eighty-four percent of the participants discontinued the habit within the first month after the device was installed. In our case, the efficacy of the fixed palatal grid could be observed from the 2nd measurement, since the restriction imposed on the parafunctional habit was favourable; from the 1st to the 2nd measurement, in an average of 3.76 weeks, a mean vertical overbite of 0.922 mm was obtained. The treatment time was 29 weeks in the longest case, with an advancement of 5.15 mm of bite closure, exceeding the overall average advancement of 3.35 mm with a duration of 17.83 weeks.
The scope of this research does not allow us to evaluate the long-term follow-up, both in terms of the results and of relapse or habits. We could only confirm that at the end of the estimated time with the grid, some patients continued treatment with removable Hawley plates for undetermined periods of time. This provided post-treatment orthodontic retention and a less invasive reminder of the harmfulness of the habit.11
CONCLUSION
Treatment of anterior open bite involves a multidisciplinary approach to ensure long-term success. However, accurate identification and correct management of the causal aetiology is crucial to achieve effective results. The fixed palatal grid decreased and eliminated the parafunctional habits that led to an anterior open bite in the 47 patients studied.
We recommend that information on malocclusions and parafunctional oral habits be more widely disseminated to parents and in schools, as a preventive and interceptive measure. With the aim of carrying out opportune treatment from an early age, where progress is faster and the required appliances are usually simpler, in comparison with adults, whose therapies are more elaborate for the correction of malocclusions.
Research on open bite is suggested in longitudinal projects of longer duration, to obtain references not only on the effectiveness, but also on the long-term stability of the use of the fixed palatal grid.
REFERENCES
AFFILIATIONS
1 Facultad de Odontología de la Universidad Autónoma de Yucatán. México.
CORRESPONDENCE
Laura Beatriz Pérez-Traconis. E-mail: laurap@correo.uady.mxReceived: Diciembre 2019. Accepted: Febrero 2020.