The masticatory function of patients with skeletal anterior open bite (OPEN) is reported to be impaired compared with that of patients with normal occlusion (NORM). In this study, we compared brain blood flow (BBF) in patients with OPEN and NORM and investigated the factors related to BBF during mastication in patients with OPEN. The study included 17 individuals with NORM and 33 patients with OPEN. The following data were collected: number of occlusal contacts, jaw movement variables during mastication, and BBF measured with functional near-infrared spectroscopy during chewing. The number of occlusal contacts, maximum closing and opening speeds, closing angle, and vertical amplitude were smaller in the OPEN than in the NORM group. Interestingly, BBF increased less in the OPEN group. Correlation analysis revealed that several parameters, including number of occlusal contacts and closing angle, were correlated with changes in BBF during mastication. These results suggest that not only occlusion but also jaw movement variables and factors related to masticatory muscles contribute to the chewing-related increase in BBF. In conclusion, BBF increases less during mastication in patients with OPEN than in those with NORM. In addition, the higher increase in BBF is correlated with jaw movement. Together, we discovered that OPEN exhibits significant adverse effects not only on masticatory function but also on brain function.

Background/Objectives: Jaw deformities affect not only facial aesthetics but also various oral functions. While previous studies have demonstrated that mandibular prognathism (MP) alters masticatory-induced brain blood flow (BBF), the temporal characteristics of these hemodynamic changes have remained unclear. In this cross-sectional observational study, we investigated the following two specific objectives: (1) whether food hardness affects not only the magnitude but also the temporal patterns of BBF changes during mastication and (2) how malocclusion is associated with these temporal hemodynamic responses. Methods: Twenty-six participants with normal occlusion (NORM) and twenty patients with MP participated in this study. BBF was measured using functional near-infrared spectroscopy, while participants chewed soft paraffin or hard gummy candy. Maximum oxygenated hemoglobin (oxy-Hb) values and time-to-peak BBF were analyzed. Results: While food hardness did not significantly affect maximum oxy-Hb within groups, the MP group showed significantly lower responses during hard gummy candy mastication compared to the NORM group. The occlusal contact area exhibited significant positive correlation with maximum oxy-Hb values, while the ANB angle, an indicator of intermaxillary skeletal relationship, showed no significant correlation with BBF parameters. The hard gummy candy/paraffin ratio of maximum oxy-Hb was significantly higher in the NORM group compared to the MP group. Time-to-peak BBF was approximately twice as long for hard gummy candy compared to paraffin in both groups, with no significant differences between groups. Conclusions: These findings reveal that while MP attenuates the magnitude of masticatory-induced BBF, particularly during hard food mastication, the temporal adaptation to increased food hardness is preserved. This dissociation between magnitude and timing effects suggests that intact basic neurovascular coupling mechanisms would be maintained even in the condition of altered masticatory function in a MP subject, which is providing new insights for rehabilitation strategies in orthognathic surgery cases.

Background/Objectives: While skeletal facial asymmetry is commonly assessed using posteroanterior (PA) cephalometric radiographs, the association between skeletal measurements and volumetric soft tissue asymmetry remains unclear. This study aimed to identify which skeletal parameters are most strongly correlated with soft tissue asymmetry measured using three-dimensional (3D) imaging. Methods: Thirty-three Japanese patients (8 males and 25 females; mean age: 26.85 ± 12.13 years) undergoing orthodontic–orthognathic treatment were included. Three-dimensional facial surface data were acquired using the VECTRA^® H1 imaging system. Soft tissue asymmetry was quantified by calculating the volumetric difference between the original and mirrored 3D facial images, divided into three regions: whole face, midface, and lower face. PA cephalometric radiographs were traced, and 28 skeletal variables were measured. Pearson correlation coefficients were calculated between skeletal variables and asymmetry volumes and squared to obtain R² values. Results: The strongest correlation with whole facial soft tissue asymmetry was found for menton deviation from the midline (R² = 0.630). Similar trends were observed for the lower face. In contrast, only one skeletal variable showed a moderate correlation with midfacial asymmetry (maximum R² = 0.186), and skeletal parameters related to maxillary occlusal cant did not show significant associations. Conclusions: Volumetric soft tissue asymmetry is strongly associated with mandibular skeletal deviation, particularly menton displacement, whereas midfacial skeletal morphology may have a limited impact. Further studies including more patients with pronounced midfacial soft tissue asymmetry are warranted.

Despite established links between masticatory dysfunction and cognitive impairment, cognitive function in dentofacial deformity patients remains unexplored. This study represents the first comprehensive cognitive assessment in mandibular prognathism (MP) patients.Brain blood flow (BBF) during chewing was measured using functional near-infrared spectroscopy in MP patients versus normal occlusion controls (NORM, n = 17). Cognitive function using eye-tracking technology (Mirudake) in MP patients (n = 44) was compared to healthy controls (HC, n = 59), with assessing six cognitive domains.MP patients demonstrated significantly reduced chewing-induced BBF in bilateral inferior frontal gyrus compared to NORM. Global cognitive performance showed no significant difference between MP and HC groups (p = 0.48). However, positive correlations existed between BBF and cognitive performance domains including global performance and memory. ROC analysis using pooled bilateral BBF data (n = 88) revealed modest diagnostic potential for cognitive assessment (AUC = 0.657, 95% CI: 0.431–0.865). The optimal threshold yielded 62.5% sensitivity, 73.8% specificity, and 72.7% overall accuracy for detecting cognitive impairment.This first systematic cognitive evaluation of MP patients revealed no significant global cognitive impairment despite confirmed reductions in masticatory-induced brain activation. The observed BBF-cognition correlations suggest BBF could serve as a novel biomarker for cognitive function assessment, warranting further investigation through longitudinal studies examining orthognathic surgery's potential cognitive effects.