Nutritional Intervention for Older Adults With Complete Dentures

Measurement of food fractionation capacity. Participants will chew a standardized food (peanuts) for 20 cycles; the particles will be dried and processed through a sieving system (sieves from 4.0 mm to 870 μm) to determine the percentage of fractionation.

Diet quality will be assessed using the Chilean Healthy Eating Index (Índice de Dieta Mediterránea for Chile, IDM-Chile), which allows the evaluation of adherence to healthy dietary patterns in the study population.

A qualitative assessment using a Grounded Theory framework conducted through semi-structured individual interviews to explore older adults' perceptions regarding their experiences with tooth loss, rehabilitation with complete removable dental prostheses, and their natural functional and social adaptation strategies in daily life. Interviews (30-60 minutes) will be audio-recorded, transcribed verbatim, and analyzed concurrently using ATLAS.ti software through progressive coding (open, axial, and selective) to develop a substantive explanatory model.

The total number of chewing cycles recorded during the mastication of a standardized food (peanuts), quantified using a 3D electromagnetic articulograph (AG501).

Assessment of chewing cycles focusing on the area, measured in square millimeters (mm²) using a 3D electromagnetic articulograph (AG501).

Assessment of the masticatory frequency during mastication, measured as the number of cycles per second (cycles/s) using a 3D electromagnetic articulograph (AG501).

Assessment of chewing focusing on the movement velocity, measured in millimeters per second (mm/s) using a 3D electromagnetic articulograph (AG501).

Measurement of maximum voluntary contraction in Newtons (N) using a digital gnathodynamometer placed between the first prosthetic molars.

Evaluation of the thickness of the masseter and anterior temporalis muscles, measured in millimeters (mm) using a portable ultrasound device with a linear transducer.

Laboratory analysis of saliva samples to quantify cortisol concentration, a biomarker of physiological stress, samples will be analyzed using a Synergy HT Multimodal Reader (Biotek, USA). The outcome will be determined via enzyme-linked immunosorbent assay (ELISA) and expressed in nanograms per milliliter (ng/mL).

Laboratory analysis of saliva samples to quantify Insulin-like Growth Factor 1 (IGF-1) concentration, a biomarker related to muscle health and growth, samples will be analyzed using a Synergy HT Multimodal Reader (Biotek, USA). The outcome will be determined via immunoassay and expressed in picograms per milliliter (pg/mL).

Laboratory analysis of saliva samples to quantify Creatine Kinase (CK) enzymatic activity, a biomarker of muscle tissue stress and health, samples will be analyzed using a Synergy HT Multimodal Reader (Biotek, USA). The outcome will be determined via spectrophotometry and expressed in Units per liter (U/L).

Laboratory analysis of saliva samples to quantify general oxidative stress by measuring reactive oxygen species (ROS) content. Saliva samples will be incubated with the CH2DCFDA fluorescent probe (30 uM) for 1 hour at 37°C in the dark. Fluorescence emission will be recorded at 530 nm using a Synergy HT multimodal reader (Biotek, USA), with H2O2 (100 uM) used as a positive control. The outcome will be reported as fluorescence intensity measured in Relative Fluorescence Units (RFU), where higher RFU values indicate a higher level of general oxidative stress.

Laboratory analysis of saliva samples to quantify total antioxidant capacity using the Oxygen Radical Absorbance Capacity (ORAC) method. The assay monitors the decay of fluorescein fluorescence (excitation/emission at 495/530 nm) over 120 minutes induced by AAPH free radicals, which is counteracted by the antioxidants in the sample. Readings will be captured every 2 minutes using a Synergy HT Multimodal Reader (Biotek, USA) and interpolated against a Trolox calibration curve. The outcome will be reported in millimoles of Trolox equivalents per milliliter of saliva (mmol TE/mL), where higher ORAC values indicate a greater total antioxidant capacity.

Evaluation of the impact of oral health on the patient's quality of life using the OHIP-7Sp questionnaire, validated for the elderly Chilean population. Total scores range from 0 to 28, where higher scores indicate poorer oral health-related quality of life.

Evaluation of global cognitive status and its subdomains (orientation, attention, memory, language, and visuospatial skills) using the Chilean version of the Addenbrooke's Cognitive Examination (ACE). The outcome is measured using the instrument's total score, which ranges from 0 to 100 points, where higher scores indicate better global cognitive efficiency.

Evaluation of executive functions, including selective attention, cognitive flexibility, inhibition, and information processing speed, administered digitally via the "EncephalApp-Stroop Test" application on a tablet. The outcome is measured as the total completion time in seconds, where shorter execution times indicate better executive performance and cognitive control.

Assessment of cerebral hemodynamics at rest focusing on the mean flow velocity of the anterior and middle cerebral arteries to evaluate neurovascular coupling. Measurements will be recorded in centimeters per second (cm/s) through Transcranial Doppler ultrasonography using a PMD-100 system (Spencer Technologies, Redmond, USA) with a 2 MHz transducer at a depth of 5 cm. The assessment will be conducted by a specialized neurologist at the neurology service of the Dr. Hernán Henríquez Aravena Hospital (Temuco, Chile).

Assessment of cerebral hemodynamics at rest focusing on the pulsatility of the anterior and middle cerebral arteries to evaluate neurovascular coupling and cerebrovascular resistance. The outcome will be calculated as a dimensionless ratio value through Transcranial Doppler ultrasonography using a PMD-100 system (Spencer Technologies, Redmond, USA) with a 2 MHz transducer at a depth of 5 cm. The assessment will be conducted by a specialized neurologist at the neurology service of the Dr. Hernán Henríquez Aravena Hospital (Temuco, Chile).

Anthropometric evaluation of nutritional status. Participants weight (measured in kilograms) and height (measured in meters) will be aggregated to calculate and report the Body Mass Index (BMI), expressed in kilograms per square meter (kg/m²).

Anthropometric assessment of abdominal fat distribution. Measurement of the participant's waist circumference, recorded in centimeters (cm) using a standardized non-elastic flexible tape measure.

Evaluation of tissue body composition, specifically assessing the total body fat percentage (%), determined via bioelectrical impedance analysis (BIA).

Evaluation of muscular health and body composition, specifically assessing the skeletal muscle mass percentage (%), determined via bioelectrical impedance analysis (BIA).