LONG-TERM EVALUATION OF THE UPPER INTERDENTAL WIDTH CHANGES COMPARING TWO TECHNIQUES: RAPID PALATAL EXPANSION AND SLOW DENTOALVEOLAR EXPANSION, FOR THE POSTERIOR CROSSBITE CORRECTION / Avaliação longitudinal das alterações das distâncias interdentárias superiores após a correção da mordida cruzada posterior, comparando-se duas modalidades de tratamento: expansão rápida da maxila e expansão lenta (dentoalveolar) do arco superior, seguidas do aparelho Edgewise

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

The long-term stability of the expansion effects still remains a controversial issue in the Orthodontic literature. So far, few studies have approached this matter in a real scientific way. In the early permanent dentition, when most orthodontic cases are referred for treatment, the posterior crossbite correction has been differently addressed: rapid palatal expansion (RPE), if there is a maxillary constriction, or slow dentoalveolar expansion (SDE), when lingual tipping plays the major role. However, at such stage of the occlusal development, both alterations are usually combined, and that is why this work aimed to study the long-term stability of these two different expansion techniques (RPE and SDE) approximately 10 years postretention of the complementing edgewise mechanotherapy. Pretreatment (T1), posttreatment (T2) and postretention (T3) study casts of 30 patients were assessed in each of the 3 groups, including a control. In either test groups, male and female adolescents had been treated for their posterior crossbites, followed by extraction or non-extraction edgewise mechanics. All changes in the interdental widths (3-3, 4-4, 5-5 and 6-6), either at T2-T1 or T3-T2, were analyzed by the paired Student´s t-test. The two-way ANOVA and the TUKEY´s test (p<0,05) were applied to compare and identify differences among the groups. Clinical variables like gender, age, extractions, sagital interarch relationships, amount of expansion, time of treatment and treatment length were all correlated to the achieved long-term results. Excepting for the 3-3 width, all other widths increased after treatment in the test groups. The control group showed to be completely devoid of posttreatment changes, although the 3-3 width significantly decreased postretention, reminding the normal development. As the RPE group demonstrated a trend toward decreasing the stability from the posterior to the anterior region of the arch, a pattern opposite to the midpalatine suture scissor-like opening, there were reasons to believe that, despite of no serious clinical implications, skeletal changes over a complex system are not maintained for a lifetime. 20% of the RPE cases, and 30% of the SDE cases, clinically relapsed after the observation period, mainly at the 6-6 width. As no specific ethiologic factor was found for the RPE group, whereas the SDE amount of expansion was directly related to the amount of relapse, this technique was deemed to be more clinically efficient, in the long-term, for the correction of the posterior crossbite in the early permanent dentition.

ASSUNTO(S)

aparelhos ortodônticos mordida cruzada

ACESSO AO ARTIGO

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