Despite the limitation of a small sample size, these results suggest that the gum-chewing task in elderly edentulous patients resulted in differential neural activity in the frontal pole within the prefrontal cortex between the 2 prosthodontic therapies-mandibular CD and IOD.

BackgroundUsing senescence-accelerated mouse prone 8 (SAMP8), we examined whether reduced mastication from a young age affects hippocampal-dependent cognitive function. We anesthetized male SAMP8 mice at 8 weeks of age and extracted all maxillary molar teeth of half the animals. The other animals were treated similarly, except that molar teeth were not extracted. At 12 and 24 weeks of age, their general behavior and their ability to recognize novel objects were tested using the open-field test (OFT) and the object-recognition test (ORT), respectively.ResultsThe body weight of molarless mice was reduced significantly compared to that of molar-intact mice after the extraction and did not recover to the weight of age-matched molar-intact mice throughout the experimental period. At 12 weeks of age, molarless mice showed significantly greater locomotor activity in the OFT than molar-intact mice. However, the ability of molarless mice to discriminate a novel object in the ORT was impaired compared to that of molar-intact mice. The ability of both molarless and molar-intact SAMP8 mice to recognize objects was impaired at 24 weeks of age. These results suggest that molarless SAMP8 mice develop a deficit of cognitive function earlier than molar-intact SAMP8 mice. Interestingly, both at 12 and 24 weeks of age, molarless mice showed a lateralized preference of object location in the encoding session of the ORT, in which two identical objects were presented. Their lateralized preference of object location was positively correlated with the rightward turning-direction preference, which reached statistical significance at 24 weeks of age.ConclusionsLoss of masticatory function in early life causes malnutrition and chronic stress and impairs the ability to recognize novel objects. Hyperactivation and lateralized rotational behavior are commonly observed with dysfunction of the dopaminergic system, therefore, reduced masticatory function may deplete the mesolimbic and mesocorticolimbic dopaminergic systems to impair the cognitive functions of selective attention and recognition memory in the prefrontal cortex and the hippocampus.

In recent years, computer-aided design (CAD) and computeraided manufacturing (CAM) have been widely integrated into clinical dentistry, particularly in the field of prosthetics. Unlike conventional methods, the new workflows of these CAD/CAM systems enable the fabrication of high-performance restorations [1,2]. Duret et al., in 1988, first reported the use of CAD/CAM technology for prosthesis fabrication [3]. Since the 1980s, many researchers have focused on the practical applications of these systems [4][5][6][7]. The advantages of CAD/CAM systems include increased productivity, lower costs, easier data management, and shorter treatment durations, which are beneficial for both dental surgeons and patients [8][9][10]. This technology has already been applied to fixed prosthetic appliances, such as inlays, crowns, and implant prosthetic components [11][12][13][14]. However, removable prostheses consist of several metallic (clasps, frameworks) and non-metallic (denture bases and artificial teeth) components, which render the application of the CAD/CAM system difficult. Therefore, the fabrication of removable prostheses using CAD/CAM has been delayed [15]. Currently, CAD/CAM complete dentures are fabricated by two companies (AvaDent; Global Dental Science, Scottsdale, AZ and DENTCA; Dentca Inc., Los Angeles, CA), and these dentures are available for use in edentulous patients [16][17][18][19][20][21][22][23]. Both companies allow definitive dentures to be fabricated in a few visits, and the dental materials, techniques, and fabrication processes have been established and standardized. The fabrication process for DENTCA dentures involves 3D printing technology (3DP) [24]. CAD/CAM dentures have been shown to achieve greater patient satisfaction than conventional complete dentures [19][20][21][22]. However,

No abstract

AimAs our society ages, the number of people living with dementia also steadily increases. Some work has focused on masticatory behaviour as a form of daily health care that could help prevent cognitive impairment and dementia. However, it is not yet clear how masticatory behaviour influences various cognitive functions. Therefore, the purpose of this study was to examine the effect of masticatory behaviour on the decline of generalized attention, an important cognitive function.MethodsParticipants were 35 healthy, dentulous individuals without stomatognathic abnormalities (24 men, 11 women; mean age: 56.8 ± 4.8 years). All participants completed three interventions: mastication, foot‐stepping, and none (control). Pre‐ and post‐intervention measures of generalized attention were measured by using neuropsychological tests to examine general attention; the results were then compared. Simultaneously, during the generalized attention task, the functional activity of the prefrontal cortex was observed on functional near‐infrared spectroscopy.ResultsResponse time of generalized attention improved in both the masticatory and foot‐stepping interventions. There was a transient increase in oxyhaemoglobin activity in the right and left prefrontal cortices in the masticatory intervention.ConclusionsMasticatory behaviour may be involved in a partial improvement of generalized attention and may induce prefrontal cortex activity in middle‐aged and older adults.