Characterization of the perinatal mandible growth pattern: preliminary results.

PURPOSE: The fetal development of the mandible is nowadays quite understood, and it is already known that craniofacial growth reaches its highest rate during the first 5 years of postnatal life. However, there are very few data focusing on the perinatal period. Thus, the present article is addressing this concern by studying the mandible morphology and its evolution around the birth with a morphometric method. METHODS: Thirty-one mandibles modelled in three dimensions from post-mortem CT-scans were analyzed. This sample was divided into two subgroups composed of, respectively, 15 fetuses (aged from 36 gestational weeks), and 16 infants (aged to 12 postnatal weeks). 17 distances, 3 angles, and 8 thicknesses were measured via the prior set of 14 landmarks, illustrating the whole mandible morphology. RESULTS: Although this methodology may depend on the image reconstruction quality, its reliability was demonstrated with low variability in the results. It highlighted two distinct growth patterns around birth: fetuses mandibles do not significantly evolve during the perinatal period, whereas, from the second postnatal weeks, most of the measurements increased in a homogeneous tendency and in correlation with age. CONCLUSIONS: The protocol developed in this study highlighted the morphologic evolution of the mandible around birth, identifying a different growth pattern from 2 postnatal weeks, probably because of the progressive activation of masticatory muscles and tongue. However, considering the small sample size, these results should be thorough, so identification and management of anatomic abnormalities could eventually be achieved.

Characterization of the very young child's palatal vault growth pattern: how do its size and shape evolve?

AIM: This study aimed to characterise the palatal vault evolution during the first years of life, both in terms of shape and size. MATERIALS: The study sample was composed of 168 healthy children aged less than 4 years. Twenty-one measurements of distances and 6 angles were taken from 7 fixed landmarks set on the palatal vaults 3D surfaces reconstructed from CT-scans. To analyse only the shape evolution, the "sizefree" log-shape ratio of those measurements were computed and the global shape of the palatal vault and their transversal curve were plotted. Statistical analyses were performed to highlight the shape and size differences separately. CONCLUSION: The shape and size evolution of the palatal vault during the first years of life was not only correlated with deciduous dentition development. We assumed that the progressive orofacial muscles activation and tongue movements in the oral cavity may also explain these results as they induced strains on the palatal vault, warping it in various ways.

Preliminary results on the impact of simultaneous palatal expansion and mandibular advancement on the respiratory status recorded during sleep in OSAS children.

INTRODUCTION: The study aimed to evaluate the evolution of the respiratory status during sleep of OSAS children treated with a custom-made device combining maxillary expansion and mandibular advancement. MATERIAL AND METHODS: Sleep studies were performed before and after the treatment for 103 children presenting an initial OSAS and Class II malocclusion. Sleep questionnaires were also addressed to parents several years after the end of the treatment to evaluate its long-term effects. RESULTS: After nine months of treatment, the sleep breathing quality significantly improved: the Apnea/Hypopnea Index systematically decreased ≤5. According to the sleep questionnaires results, 84% of the patients did not show any loud or troubled breathing several years after the end of the treatment. DISCUSSION: Simultaneous maxillary expansion and mandibular advancement induced an increase of the oral space in the three spatial dimensions, helping in the significant improvement of the OSAS symptoms, with long-terms effects on the sleep breathing quality.