Abstract
Background/Objectives: Studies have examined the mechanisms of oral hypofunction by investigating the relationship between the number of remaining teeth, bite force, mastication ability, and lateral induction factors influencing chewing pathways. However, many previous studies have not consistently assessed the same individuals across all these factors, leaving key contributing factors unaddressed. This study aimed to develop a reliable oral hypofunction model using non-invasive mouthpieces. We hypothesized that it is possible to reproduce a model of oral hypofunction in healthy individuals using a mouthpiece by modifying occlusal contact areas and lateral induction factors.
Methods: A total of 10 healthy adults (five men and five women; mean age: 28.4 ± 1.5 years old) with normal occlusion and no stomatognathic abnormalities participated in this study. Experiments were conducted under four conditions: (1) no mouthpiece; (2) a mouthpiece with large occlusal contact areas and canine guidance; (3) a mouthpiece with large occlusal contact areas but no canine guidance; and (4) a mouthpiece with small occlusal contact areas and no canine guidance. The outcomes assessed were maximum bite force, occlusal contact area, mastication ability, and salivation.
Results: A strong positive correlation was identified between occlusal contact area and maximum bite force (p < 0.001). Furthermore, occlusal contact was positively correlated with mastication ability (p < 0.001). The glucose concentration of the filtered solution decreased significantly from Condition I (mean: 203.3 (SD = 42.7) mg/dl) to Condition IV (mean: 90.2 (SD = 14.2) mg/dl) (Figure 9). The presence of lateral induction factors, such as canine guidance, demonstrated a significant influence on these outcomes (p < 0.05).
Conclusions: The findings align with those of previous studies and validate the use of this mouthpiece model for simulating oral hypofunction. This model, adaptable for use in healthy individuals, supports larger-scale studies under controlled conditions to better elucidate the mechanisms underlying oral hypofunction.
Introduction
Mastication is a fundamental component of the stomatognathic system and is crucial in sustaining overall health and life [1]. Malocclusion negatively impacts masticatory function, and its relationship with factors such as the number of remaining teeth, bite force, and chewing ability, as well as occlusal guidance influencing mandibular trajectories, have been extensively studied. However, many of these studies have been limited to group comparisons between individuals with healthy oral function and those experiencing hypofunction, often neglecting intra-individual variability. Consequently, the potential interplay between additional factors, such as oral hygiene, dryness, bite force, and tongue-lip movement remains insufficiently understood . Furthermore, it is important to note that oral hypofunction does not only affect the mechanical aspects of mastication but also has far-reaching implications for systemic health, including nutritional deficiencies and an increased risk of frailty in the elderly population .
We hypothesized that it is possible to reproduce a model of oral hypofunction in healthy individuals using a mouthpiece by modifying individual factors. In this study, by only using a mouthpiece the conditions of the occlusal contact state can be changed and examined its impact on other conditions. While previous studies have manipulated occlusal factors, such as occlusal contact areas and canine guidance, using intraoral appliances, to our knowledge, no study has specifically compared different occlusal conditions while maintaining a given mouthpiece thickness. The novelty of our study lies in ensuring that factors other than occlusion remain consistent, allowing for precise evaluation of occlusal effects. This approach allows for an analysis of functional declines under controlled conditions, offering insights into the nuanced interplay of multiple factors that influence oral function.
