Cross-sectional study of correlation between mandibular incisor crowding and third molars in young Brazilians

Av. Limeira, 901 P.O. Box: 52, Department of Morphology, Anatomy area, State University of Campinas Unicamp, 13414 903, Piracicaba, SP, Brazil, .
Medicina oral, patologia oral y cirugia bucal (Impact Factor: 1.17). 02/2013; 18(3). DOI: 10.4317/medoral.18644
Source: PubMed


Objectives: The aim of this study was to evaluate transversally the clinical correlation between lower incisor crowding and mandible third molar.
Study Design: Three hundred healthy volunteers (134 male and 166 female), aged 20.4 (±2.4) years-old were submitted to a complete clinical examination and filled up a questionnaire about gender, age, total teeth number and presence or absence of superior and inferior third molar. After a recent panoramic radiography were evaluated. The multiple logistic regression showed that none of the studied factors influenced the mandibular incisor crowding.
Results: The proportion of both molars present or both absent was higher than the other conditions (Chi-square, p<.0001). The multiple logistic regression showed that any of the studied factors, influenced (p>.05) the mandibular incisor crowding. Despite the statistical significance, wear orthodontics appliances showed a little correlation (odds ratios < 1.0) in the mandibular incisor crowding.
Conclusion: Presence of maxillary and/or mandibular third molars has no relation with the lower incisor crowding.

Key words:Malocclusion, third molars, lower incisor crowding, mandible.

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    • "They concluded that there is no evidence to implicate third molars as etiologic factors in the late lower dental arch crowding [3]. In addition, Karasawa et al. [4] evaluated three hundred subjects with a mean age of 20.4 years on the presence or absence of wisdom teeth and mandibular incisor crowding. They also found no statistically significant association between the presence of upper and/or lower third molars and anterior mandibular teeth crowding. "
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    ABSTRACT: Aims: To evaluate the role of third molars in the development of crowding or relapse after orthodontic treatment in the anterior segment of the dental arch. Methods: PubMed search of the literature was performed selecting all the articles relevant to the topic and limiting the studies to controlled trials on humans and written in English language. Systematic review was conducted according to the PRISMA (preferred reporting items for systematic reviews and meta-analyses) statement. Results: A total of 12 clinical studies were included in the review. A high risk of bias was found in most of the articles, either because the relative items assessed were inadequate or because they were unclearly described. The third molars were not correlated with more severe anterior tooth crowding in most of the studies. However, four of them described a different outcome. Conclusion: Definitive conclusions on the role of the third molars in the development of anterior tooth crowding cannot be drawn. A high risk of bias was found in most of the trials, and the outcomes were not consistent. However, most of the studies do not support a cause-and-effect relationship; therefore, third molar extraction to prevent anterior tooth crowding or postorthodontic relapse is not justified.
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    ABSTRACT: The role of third molars as a cause of incisor crowding, especially in the lower arch, continues to be controversial. The aim of this work is to compare opinions of Italian oral surgeons and orthodontists on this topic. One hundred ninety-three Italian practitioners of the Society of Orthodontics (SIDO) and the Italian Society of Oral Surgery (SICOI) were asked to fill out an online questionnaire made up of six questions. Practitioners were asked to express their opinion on the relation between upper and lower third molar eruption and anterior crowding. One hundred sixty-six members of both societies completed the online research survey; response rate (RR) was 86%. There were no statistically significant differences between the two groups (P > 0.005). Both agree not to believe that third molars create a force responsible for anterior crowding in the upper (82.5% orthodontists, 83.8% surgeons) and in the lower arch (52.6% orthodontists, 63.8% surgeons). Both agree also not to consider the upper (89.7% orthodontists, 82.1% surgeons) and lower (58.8% orthodontists, 63.2% surgeons) third molar extraction useful to prevent crowding. Italian orthodontists and oral surgeons have the same opinion on the role of the third molar in causing anterior crowding. The majority of both groups of clinicians do not consider their preventive extraction useful in order to prevent anterior crowding.
    Progress in Orthodontics 11/2014; 15(1):60. DOI:10.1186/s40510-014-0060-y
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