Cibelle Cristina Oliveira dos Santos, Renata Travassos da Rosa Moreira Bastos, Silvio Augusto Bellini‑Pereira, Daniela Garib and David Normando
What did the authors aim to do in this study?
The primary objective of this study was to evaluate the physiological behaviour of the mandibular incisor crowding in the transition from mixed to permanent dentition.
How did the authors evaluate?
This systematic review was carried out by taking into consideration five electronic databases which were a part of the search strategy. They included the PubMed, Scopus, Web of Science, LILACS & LIVIVO. The Gray literature search included Proquest & Google Scholar. Apart from this, even a hand search was conducted in the reference lists of the included articles in case of any missing relevant studies related to the research topic. No particular language restriction was applied and also the coverage dates were also not limited.
Among the five included studies, four presented moderate and one low risk of bias. Some concerns related to the risk of bias were due to no control for confounding factors by studies that adjusted only the variable sex as a confounding factor in determining the results. Also, one study measured mandibular incisor crowding using photographed dental models, which introduces a risk of bias in the measurement of exposure.
What did the authors find?
The authors in total identified around 2,663 studies & among the 2,663 studies identifed, five were selected for qualitative analysis, of which one has a low risk of bias, and four, a moderate risk. A total of 243 patients were evaluated. Evidence with a high level of certainty was generated indicating a tendency for improvement in mandibular incisor crowding from mixed to permanent dentition, with mandibular incisor crowding decreasing from 0.17 to 4.62 mm on average. The mandibular incisor crowding reduction seems to be associated with the amount of initial crowding and spontaneous dental arch dimensional changes that occur in the mixed dentition and culminate in the increase in arch perimeter, leeway space, incisor protrusion and transverse growth of the maxillary and mandibular arch.
What did the authors conclude?
• From five cohort studies, evidence was generated with a moderate level of certainty that mandibular incisor crowding reduces in the transition from mixed to permanent dentition by up to 4.62 mm, even in children with good occlusion. Also, the greater the mandibular incisor crowding in the mixed dentition, the greater the self-correction in the permanent dentition.
• In addition to the initial magnitude, other factors are associated with self-correction of childhood crowding, including leeway space, increased permanent incisor protrusion, and increased maxillary arch width.
• In orthodontic planning, the clinician can base their decision on the possibility of spontaneous alignment of mandibular incisor in childhood in children with crowding magnitudes up to 4 mm.
• It should be highlighted that the studies included in this review presented considerable variability. Thus, further prospective studies with greater methodological rigor may produce more accurate results.
What do we think about it?
Although there are various types of malocclusions present, the most obvious & the most evident is the presence of crowding. This commonly causes a concern for the patient both esthetically & functionally, Hence a huge factor that inspires parents to bring in their child to the dental clinic for a checkup, worried about their irregularly placed teeth. In order to treat such cases in young patients, it is essential for the clinician to know to what extent this anomaly is self-corrected & when an intervention is required. This systematic review gives a clear evidence with scientific basis for planning longitudinal follow ups in patients with mild to borderline moderate mandibular incisor crowding in the mixed dentition avoiding overtreatment. Although there were very good inputs put forth by the review, it also showcased limitations such as the lack of primary studies & the lack of methodological rigor within some of the studies that were selected. Apart from this, most studies could not clearly emphasize which factors influenced the self-correction of the crowding as the dentition transitioned from mixed to permanent. Inspite of all these shortcomings, this review truly helps the clinician understand the extent of self correction in lower incisor crowding in a growing patient and how to plan the treatment accordingly.
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