RESUMO
OBJECTIVE: The objective of this study was to determine the developments, morphometric features, and shapes of the maxillary and mandibular arches during the prenatal period in a large series of fetal material. METHODS: The study was carried out on 225 human fetuses aged between 8 and 40 weeks of gestation. General, extraoral, and intraoral parameters were taken from each fetus. The width and depth measurements and the shapes of the maxillary and mandibular arches were achieved using the casts obtained. The arches were categorized according to the shapes of the anterior and posterior regions of the arches. RESULTS: Palatal and mandibular indices did not change during the prenatal period. Maxillary arch measurements were greater than the mandibular measurements. Moreover, width measurements of both arches were greater than the depth measurements during fetal life. We found that the frequencies of triangular maxillary and mandibular arches were highest in the first and second trimesters; whereas, the square model became more frequent in the third trimester and at full term. Classification of the arches according to their posterior regions showed that the tips of the arches shifted medially toward the term. There were significant correlations between width and depth parameters of the arches and extraoral parameters. CONCLUSION: Data obtained in the study would be useful for clinicians by presenting an objective scale related to the prenatal period as well as being helpful in assessing the development of this region, identifying the anomalies and pathologies, and assisting treatment.
