| Abstract|| |
Background: Functional posterior crossbites are a common finding in children with deciduous teeth and must be treated as soon as they are diagnosed in order to avoid unwanted changes in normal growth and development patterns.
Objective: This study objective was to evaluate the changes caused by Planas' direct tracks treatment on the arch dimensions of patients with functional posterior crossbite in first dentition.
Materials and Methods: The sample consisted of 20 children, 4 to 6 years old, divided into two groups, paired up according to age and gender. Group test was composed of 10 patients with functional posterior crossbite treated with PDT. Group control consisted of 10 children with normal occlusion. The evaluation criteria were intercanine and intermolar distances and Carrea's analysis (arch perimeter). All data were collected by a pre-calibrated examiner on study casts obtained at baseline and after 4 months of treatment. The statistical analysis of the data was achieved using GraphPad InStat software, version 3.05 for Windows, with the level of significance set at 0.05. For the comparison between intercanine and intermolar distances, the Tukey-Kramer Multiple Comparisons test was used. When Carrea's analysis was considered, the Mann-Whitney test was used.
Results: At the beginning of the study, all the evaluated criteria showed lower mean values in patients with posterior crossbites, and significant differences between test and control groups were noticed (P<0.05). After the end of follow-up period, these differences could not be verified (P>0.05).
Conclusions: Within the limits of the present study, it is possible to conclude that the treatment with Planas' direct tracks was able to give back the normal dimensions of deciduous arch in patients with unilateral functional posterior crossbites, thus making it possible a better growth pattern.
Keywords: Crossbite, Planas′ direct tracks, malocclusion
|How to cite this article:|
Chibinski AR, Czlusniak GD. Evaluation of treatment for functional posterior crossbite of the deciduous dentition using Planas' direct tracks. Indian J Dent Res 2011;22:654-8
Malocclusion is considered by the World Health Organization as the third most important public health dental problem.  According to Silva Filho et al,  about 73.26% of children at deciduous dentition phase have some type of malocclusion. The authors evaluated the occlusion of 2016 children, between 3 and 6 years old, and observed that half of the children with malocclusion (35.24%) showed some type of crossbite (unilateral or bilateral, anterior, posterior or total).
|How to cite this URL:|
Chibinski AR, Czlusniak GD. Evaluation of treatment for functional posterior crossbite of the deciduous dentition using Planas' direct tracks. Indian J Dent Res [serial online] 2011 [cited 2014 Apr 19];22:654-8. Available from: http://www.ijdr.in/text.asp?2011/22/5/654/93451
The normal intermaxillary relationship is characterized by the involvement of the lower occlusal faces by the upper ones, so that the mandibular lateral movement is restrained and absorbed by the maxilla, which, in turn, requires this excitation in order to develop. 
If there is a crossbite, this process is modified, and situations such as maxillary atrophy, mandibular postural disturbance during sleep or premature occlusal interferences are created. As a consequence, centric occlusion becomes an uncomfortable position for the child, who gets used to laterally deviating the mandible after closing, in order to find a more comfortable position.  Thus, the child elects the deviated position as his/hers habitual occlusion, causing a significant difference between the positions of centric relationship and habitual maximum intercuspation. This is the most prominent characteristic of functional posterior crossbites.
The deviated condyle on the affected side will interfere on the balance between form and function of the temporo-mandibular joint. The crossed side becomes the side of minimum vertical dimension, in other words, the region of maximum intercuspation and preferred mastication side, albeit an unconscious option from the part of the child. The resulting asymmetric growth alters the normal development of the face. ,,
Based on the above, it is fundamental to regain the normal growth and development patterns of the face as early as possible, in order to avoid significant alterations of the skeletal base. This is the objective of functional crossbites treatment with Planas' direct tracks. ,
The technique seeks a change of mandibular posture by associating tracks made of composite resin with selective grinding of premature dental contacts, trying to de-program muscular and nervous centers already adapted to the deviation, followed by readjustment to the appropriate position. , This technique is indicated by several researchers, such as Bertele,  Brandão,  Gribel,  Limme,  Neto; Puppin-Rontani; Garcia  and Simões. ,
The treatment of functional posterior crossbite with PDT shows several characteristics that make it an attractive option in Dentistry. One of the main advantages is the fact that the patient's collaboration is not needed, since it is based on "adhesive restorations" and selective grinding, which remain active 24 hours per day, 7 days a week. This technical peculiarity guarantees the conservation of the correct intermaxillary relationship during the activation of facial growth functions, such as mastication, which is fundamental for treatment, because it is during this phase that a large part of development takes place.  The low cost of the technique should also be pointed out, and since it does not require special equipment or materials, it raises the possibility of its use in Public Health. 
Based on the above, the objective of this study was to evaluate the changes caused by Planas' direct tracks treatment on the arch dimensions of patients with functional posterior crossbite in first dentition.
| Materials and Methods|| |
The present study received approval from the Ethic Committee of the Ponta Grossa State University. All the parents/caregivers were invited to an initial meeting with the clinical researcher and they were informed of the nature of the study. After that, they signed a consent form, according to the Helsinki Declaration (version 2002) and the Dentistry Ethical Code (CONEP/MS, Brazil).
The study was carried out at a full-time public school. The sample inclusion criteria were: complete deciduous dentition, age between 4 to 6 years old and the presence of unilateral functional crossbite. The exclusion criteria were the presence of endodontic problems, premature lost of deciduous teeth, and presence of deleterious habits (pacifier our finger sucking).
A total of 90 children were examined. After this, 20 patients were selected. Parents or guardians of the 20 children signed a consent form. These patients received basic dental treatment before the beginning of this research, consisting of hygiene instructions, fluoride application, and dental restorations, if needed.
Test group consisted of 10 children with functional unilateral posterior crossbite. For the differential diagnosis between functional and true posterior crossbite, all the children had their mandible manipulated during the clinical exam, taking it to the centric relationship and to the position of maximum intercuspation. The midline discrepancy between centric relationship and centric occlusion reveals the existence of mandibular deviation. In the case of a functional crossbite, if the mandible is taken to its centric relationship, the midline will coincide. This indicates that the deviation is due, probably, to occlusal interferences during functional movements. On the other hand, in true crossbite, which is characterized by unilateral underdevelopment, among other signs, there is no significant change in mandibular posture in the position of centric relationship and maximum intercuspation. This diagnostic protocol is proposed by several authors. ,,
For the control group, 10 children, with normal occlusion and matching age and gender, were selected. Normal occlusion was considered as the absence of openbites or crossbites and Class I relationship between deciduous canines and second molars.
Study casts were obtained in both groups at the baseline and after 4 months. The casts were analyzed by a pre-calibrated examiner (Kappa index = 0.89) using the following criteria: intercanine and intermolar distances and Carrea's analysis of upper arches.
Intercanine and intermolar distances were measured with a needlepoint drawing compass and a millimeter ruler. The drawing compass was placed on the cusp tips of homologous canines (intercanine distance) and on the occlusal-palatal fissure of the homologous second deciduous molars (intermolar distance). After registering the distance, the compass was superimposed on a ruler to obtain the real distance in millimeters.
For Carrea's analysis, the researchers prepared four acrylic plates with a triangle circumscribed by circumferences of different diameters (29, 30, 32 e 34 mm).
Tracks were built on canines and molars, in order to offer a physical support barrier capable of avoid the return to the patient's normal occlusion (crossbite). For this purpose, it was used light cured composite resin (Z100 - 3M), in an adhesive direct technique.
It was ensured that the tracks had a wide final configuration in order to block the mandible return to the deviated position, and were thick enough to avoid fracture when in use.
As the premature contact of canines contributed to mandibular deviation, selective grinding was done with high-speed, refrigerated, diamond burs # 3053 (wheel-shaped), and # 3118 (flame-shaped) (KG Sorensen). A layer of fluoridated varnish was applied on the teeth that received compensatory grinding, with the objective of preventing sensibility.
The tracks were kept in function for four months, with monthly clinical follow-ups. At the end of this period, the balance in the development of the stomatognathic system was determined, and the tracks were removed. This step was carried out with diamond burs # 1192F and/or 3118F and scalpel (# 12 blade), followed by surface polishing with Soflex (3M) discs and e Enhance finishing points (Dentsply).
At this moment, new casts were obtained from patients in test and control groups, in order to verify the changes on the evaluated criteria.
The statistical analysis of the data was achieved using GraphPad InStat software, version 3.05 for Windows, with the level of significance set at 0.05. For the comparison between intercanine and intermolar distances, the Tukey-Kramer Multiple Comparisons test was used. When Carrea's analysis was considered, the Mann-Whitney test was used.
| Results|| |
At the beginning of this study, it was observed significant differences between test and control groups in all the evaluation criteria used [Figure 1],[Figure 2], and [Figure 3].
|Figure 1: Mean and standard deviation of upper intercanine distance in control and test groups at baseline and after 4 months of follow-up. Different letters denote significant differences (P<0.05 -Tukey Multiple Comparison Test)|
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|Figure 2: Mean and standard deviation of upper intermolar distance in control and test groups at baseline and after 4 months of follow-up. Different letters denote significant differences (P<0.05 -Tukey-Kramer Multiple Comparison Test)|
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|Figure 3: Mean and standard deviation of Carrea's analysis in control and test groups at baseline and after 4 months of follow-up. Different letters denote significant differences (P<0.05 -Mann-Whitney Test)|
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When intercanine distance was considered, differences were observed between control and test groups on the baseline (P<0.01) and in test group pre and post treatment (P<0.05). There were not significant differences between the groups after 4 months of follow-up (P>0.05) [Figure 1].
Intermolar distance showed statistical differences when comparing baseline and post-treatment means for test group (P<0.001). Control group showed no differences between baseline and 4 months follow-up (P>0.05). After 4 months, no differences were verified between control and test groups (P>0.05) [Figure 2].
Carrea's analysis did not show variations on values in control group at baseline and after 4 months. The differences were observed only on test group, when comparing baseline and 4 month's follow-up (P<0.02) [Figure 3].
At the end of the 4 months follow-up, all the mean values showed a little increase [Table 1] for the test group, a difference of 5.78% in intercanine distance and 2.03% in intermolar distance was observed; in control group, these percentages were 2.15% and 4.15%, respectively. Control group had no modifications when Carrea's analysis was considered; test group had an increase of 2.22%.
|Table 1: Mean values of control and test groups at baseline and 4 months after treatment|
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| Discussion|| |
This study demonstrated that the difference between the intercanine and intermolar distances of children with functional crossbite and normal occlusion was significantly reduced after the use of Planas' direct tracks. The probable explanation for this is the change induced by the tracks on the axial axis of canines and molars. Similar results, showing larger horizontal and vertical planes were observed by Neto, Puppin-Rontani, Garcia.  The authors analyzed the masticatory cycle after selective grinding on deciduous teeth and composite resin occlusal guidance for posterior crossbite correction.
A reduced arch perimeter, as verified at baseline evaluation on test group patients, could act like a barrier to normal growth patterns.  It was observed on test group at baseline evaluation, when Carrea's analysis was used. After track construction, differences between control and test groups were reduced to the point of not having statistical significance.
The literature confirms that the favorable clinical solution was possible only because the intervention occurred at a very early age, when treatment can take advantage of the favorable dynamics of the children's tissues to remodel and accommodate the stomatognathic system as a whole, and mainly because the initial diagnosis was correct. ,, This is a relatively short stage of occlusion development, on average lasting between the ages of 3 and 6 years. Although very young, by the end of this period the child already presents approximately 75% to 80% of the adult's sagittal dimensions. Modifications on skeletal, muscular, and nervous structures may become permanent in the subsequent phases, extending into the periods of mixed and permanent dentitions. 
In most cases, the level of success of this orthopedic treatment is related to the selective grinding of the premature occlusal contacts, evidenced when the mandible is taken to the position of centric relationship. It is fundamental that the lateral movements can be done freely, balanced on both sides, or with simultaneous contacts during work and in balance, with the objective of having the temporomandibular joint exert its physiological function. In general, these contacts occur on deciduous canines and vestibular cusps of the molars on the non-crossed side. , After the confirmation of the occlusal contacts with carbon paper, selective grinding should be carefully done with high-speed wheel-type diamond burs. Grinding of occlusal interferences is indicated by authors such as Planas, , Thilander et al,  Belanger,  Brandão  and Simões. ,
It should be noted, however, that in the majority of the clinical situations seen in daily practice, malocclusion involves several disorders that require interdisciplinary interventions in order to reach the ideal occlusion. Starting with dental care for babies, up to the establishment of an adult occlusal pattern at the end of adolescence, the development of the patient's stomatognathic system must be followed, so that preventive and/or interceptive therapies can be implemented at the right time. Thus, Planas direct tracks can be considered a stage of the treatment, preventing the establishment of changes of the skeletal base and creating more favorable conditions for future orthodontic or orthopedic treatments, if needed.
| Conclusion|| |
Within the limits of the present study, it is possible to conclude that the treatment with Planas' direct tracks was able to give back the normal dimensions of deciduous arch in patients with unilateral functional posterior crossbites, thus making it possible a better growth pattern.
| References|| |
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Ana Cláudia R Chibinski
Department of Dentistry, Ponta Grossa State University, School of Dentistry, Ponta Grossa, Paraná
[Figure 1], [Figure 3]
[Table 1], [Figure 2]