Exploring directional and fluctuating asymmetry in the human palate during growth.

OBJECTIVES: Palate morphology is constantly changing throughout an individual's lifespan, yet its asymmetry during growth is still little understood. In this research, we focus on the study of palate morphology by using 3D geometric morphometric approaches to observe changes at different stages of life, and to quantify the impact of directional and fluctuating asymmetry on different areas at different growth stages. MATERIALS AND METHODS: The sample consists of 183 individuals (1-72 years) from two identified human skeletal collections of 19th and early 20th Century Italian contexts. A 3D-template of 41 (semi)landmarks was applied on digital palate models to observe morphological variation during growth. RESULTS: Asymmetrical components of the morphological structure appears multidirectional on the entire palate surface in individuals <2 years old and become oriented (opposite bilateral direction) between 2 and 6 years of age. Specifically, directional asymmetry differentially impacts palate morphology at different stages of growth. Both the anterior and posterior palate are affected by mild alterations in the first year of life, while between 2 and 6 years asymmetry is segregated in the anterior area, and moderate asymmetry affects the entire palatal surface up to 12 years of age. Our results show that stability of the masticatory system seems to be reached around 13-35 years first by females and then males. From 36 years on both sexes show similar asymmetry on the anterior area. Regarding fluctuating asymmetry, inter-individual variability is mostly visible up to 12 years of age, after which only directional trends can be clearly observed at a group level. DISCUSSION: Morphological structure appears instable during the first year of life and acquires an opposite asymmetric bilateral direction between 2 and 6 years of age. This condition has been also documented in adults; when paired with vertical alteration, anterior/posterior asymmetry seems to characterize palate morphology, which is probably due to mechanical factors during the lifespan. Fluctuating asymmetry is predominant in the first period of life due to a plausible relationship with the strength of morphological instability of the masticatory system. Directional asymmetry, on the other hand, shows that the patterning of group-level morphological change might be explained as a functional response to differential inputs (physiological forces, nutritive and non-nutritive habits, para-masticatory activity as well as the development of speech) in different growth stages. This research has implications with respect to medical and evolutionary fields. In medicine, palate morphology should be considered when planning orthodontic and surgical procedures as it could affect the outcome. As far as an evolutionary perspective is concerned the dominance of directional asymmetries in the masticatory system could provide information on dietary and cultural habits as well as pathological conditions in our ancestors.

VFMSS findings in elderly dysphagic patients: our experience.

BACKGROUND: Dysphagia consists in alteration of the swallowing mechanism, due to different pathological conditions, which can occur at different levels. The exact prevalence of dysphagia is unclear, even if some AA suggest that 15% of the elderly population is affected. Aim of this study is to analyze the main VFMSS findings in elderly dysphagic patients. MATERIALS AND METHODS: The VFMSS of 59 elderly dysphagic patients (32 women, 27 men, ranging in age from 68 to 89 years, mean 81 years) who undergone speech therapy assessment and videofluoromanometric (VFM) investigation of the swallowing process at our institution from January 2011 and December 2012, were retrospectively reviewed. RESULTS: In the oral phase the preparation and the initial stage of swallowing should be explored by videofluoroscopy evaluating the ability to contain food in mouth and to form a bolus and whether there is an inadequate convergence of Passavant's ridge with preswallowing aspiration. In the pharyngeal phase is necessary to evaluate at videofluoroscopy if there is penetration and/or aspiration and the efficacy of laryngeal closure should be assessed too. CONCLUSION: The VFSS represents a fundamental examination in the management of the dysphagic patient; this investigation may be associated with manometry providing anatomical and functional informations.