This study aims to evaluate whether or not there is a higher prevalence of skeletal abnormalities in subjects with maxillary canine impaction (MCI). This retrospective study was performed on 67 subjects with maxillary canine impaction (test group) and on 67 patients without dental displacement (control group). Sella turcica bridging (SB), ponticulus posticus (PP), atlas posterior arch deficiency (APAD) and the morphology of sella turcica and pterygopalatine fissure were evaluated on lateral cephalometric radiographs. Statistical analysis was performed using chi-square, Mann–Whitney test and multivariate logistic models; the level of significance was p < 0.05. Results showed that in the test and control groups 87% and 62.7% of patients had SB, respectively. PP was observed in 60% of patients in the test group and in 16.4% of patients in the control group. APAD was observed in 9% of test group and in 4.5% of the control group. Skeletal anomalies were significantly increased (p < 0.05) in subjects with MCI. A significant difference between the groups was observed in regards to the shape of the pterygopalatine fissure, found to be less wide and longer in the test group. SB, PP and APAD were higher in subjects with MCI; furthermore, an elongated pterygopalatine fissure was significantly associated with MCI.

Masticatory dysfunction is a risk factor for Alzheimer 's disease (AD), likely due to the trigeminal influences on the Locus Coeruleus (LC), a structure implicated in neurodegenerative processes and whose activity level is reflected by pupil size. Chewing activity acutely stimulates cognitive performance by increasing LC activation during task, as reflected by an increased pupil dilatation (mydriasis). The presence of a trigeminal sensorimotor imbalance is associated to an asymmetry in LC activity (reflected by an asymmetry in pupil size) and is detrimental for performance. These observations prompt for developing testing procedure, in normal elders and in patients affected by AD, aimed to: 1) study the presence of trigeminal asymmetries and to assess the possible contribution of occlusal correction in improving the subject's condition and in preventing/delaying the AD development; 2) verify the stimulating effect of chewing on cognitive performance and task-related mydriasis as an estimate of the LC excitability for determining the subject condition and its susceptibility to undergo AD development. Procedures appropriate for achieving these goals are proposed.