Efficiency of chewing load deficiency correction in clinical dental practice

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Chewing contributes to the normal functioning of the dental system, plaque removal from teeth, and saliva production. Poor chewing has negative effects, especially on the periodontium [1].

Additionally, eating soft foods does not remove food particles from teeth’s surface. Heat processing, softening, and crushing of food improves the taste of food and reduces time for chewing and eating. Concentrated food reduces eating and chewing time, time spent in the mouth, and stress on the dental system. This gradually contributes to lazy chewing and decreases the load on the entire dental system. Lazy chewing and concentrated food consumption significantly contribute to the decreased natural self-cleaning ability of the human mouth, which, along with sugar consumption, leads to tooth decay [1, 2].

Study of the functional morphology of a human skull revealed the main trend of its evolution: progressive size reduction of the chewing system, including the upper and lower jaws and teeth. For example, the chewing surface of human teeth has nearly halved over the past 100,000 years [1]. Additionally, changes in the way the third molars (wisdom teeth) form, develop, and erupt are obvious, visible, and well-known signs [1].

Jaw reduction has led to the fact that in the majority of the general population, even immature third molars are undetected; in many cases, they form inside the jaw and do not erupt [1]. When they do erupt, they are difficult to erupt or should be removed owing to lack of space [1]. Therefore, eventually, humans are predisposed to complete loss of the third molars, which is one of the main consequences of dental system reduction [1].

In addition to microbial factors, local hemodynamic and tissue perfusion abnormalities are believed to be crucial in the pathogenesis of periodontal and dental diseases [2]. They are pathogenetically triggered by functional changes in the periodontal vessels due to decreased masticatory load, which leads to tissue hypoxia [3].

Masticatory load is the main functional load applied to periodontal tissues, resulting in functional hyperemia. The response of the periodontal vasculature to masticatory load depends on the use of available functional reserves and status of blood flow regulation [2, 3].

Moreover, the mechanical factor of masticatory load increases the mineralization level of the hard tissues of the intact masticatory teeth and decayed teeth, which can be used to prevent dental decay when employing the optimal additional masticatory load [4].

A gnathotraining system guided by functional diagnostic techniques was developed to hinder hypodynamia of the masticatory apparatus to prevent destructive processes in its structures [5]. It includes electrical stimulation of the masseter muscles for physiological parameters mimicking a chewing effect and gnathodynamic training using chewing gum. Electrical stimulation is used in cases of significant chewing dysfunction.

A study by Park et al. showed that neuromuscular electrical stimulation synchronized with chewing exercises is more effective in increasing biting force and masseter muscle thickness [6]. Functional training improves chewing in patients with mandibular prognathism [7].

It was found that jaw exercises are an effective treatment and are recommended for patients with temporomandibular joint (TMJ) pain and jaw dysfunction [8, 9].

A systematic review revealed the beneficial effect of exercise in treating myogenic and arthrogenic TMJ dysfunction. Notably, active and passive oral exercises may be effective in reducing musculoskeletal pain and improving oromotor function [10].

Considering the fact that chewing gum does not compensate the deficit of masticatory load in modern society, so-called gnatotraining (use of chewing gum) by NK Loginova was developed in 2000 by authors from the Kazan State Medical University headed by Professor SS Ksembaev, which was joined in 2008 by the Department of Medical Engineering of the Kazan National Research Technological University headed by Associate Professor IN Musin [11]. The result of this joint work was a Russian Denta Fit dental trainer, which was then scaled up for industrial production [12].

The dental jaw trainer was developed using IR-21 silicone rubber and manufactured at the Department of Chemistry and Technology of Elastomer Processing of the Kazan National Research Technological University [13].

The potential of including dental and jaw training in a program of treatment and preventive measures has been demonstrated, which allows to improve dental status and in turn prevent dental decay and periodontal diseases and form an appropriate dental occlusion in children [13].

The use of the dental trainer increased the neuromuscular activity of the masseter muscles and improved regional blood flow (i.e., increased linear velocity of blood flow and decreased resistance coefficients). The stimulating effect of dental and jaw training on the rate of saliva secretion and its mineralizing potential and the functional resistance of tooth enamel have been demonstrated. Regular use of the dental trainer was shown to decrease the rate of decay progression [14].

The stimulating effects of dental and jaw training on the functional status of the salivary glands and periodontal microvascular network were a relevant increase in the salivary flow rate, a decrease in the total white blood cell (WBC) count, and an increase in the live WBC count in oral fluid. During the rehabilitation period, dental and jaw training combined with toothbrushing improved personal oral hygiene in patients [15].

Mathematical modeling of the hydrodynamic effect confirmed the effectiveness of using a dental trainer to clean the vestibular, palatal, lingual, and buccal surfaces of teeth. Study of the effects of dental training on the composition and properties of the oral fluid revealed no abnormalities in the periodontium. This indicated that dental training does not activate the prooxidant system, which prevents an abnormal reaction resulting in degenerative lesions and periodontium destruction [16].

The need for myofunctional disorder treatment in combination with orthodontic treatment is well established. The authors noted that treating myofunctional disorders with appropriate loading during exercise may reduce treatment time for dentoalveolar anomalies [17].

The effectiveness of this approach has been confirmed in patients with mandibular fractures. Dentoalveolar training improved severity of muscular and articular TMJ disorders (using the short Hamburg test), bringing the parameters of the main group almost to the functional norm, compared to those of the control group, which remained at risk. Therefore, adding dental and jaw training to a rehabilitation program for mandibular fractures was found to reduce associated musculoskeletal disorders [18].

Dental and jaw training in children with permanent occlusion induces a stimulating effect on the salivary secretion rate, maintains the hydrogen index (pH) of the oral fluid at a neutral level, and, in combination with toothbrushing, provides optimal dental hygiene [13].

New challenges stimulate improvement of the dental trainer. For example, devices for treating myofunctional disorders of the dental system [19] and TMJ dysfunction [20] associated with adverse changes in masseter muscle function have been developed.

Studies confirmed the effectiveness and feasibility of using dental trainers to improve dental health as a new approach for the prevention and treatment of dental disease.

The effects of increased neuromuscular activity of the masseter muscles and regional vascular tone indirectly indicate that the dental system receives adequate mechanical load for the normal functioning of all its elements.

ADDITIONAL INFORMATION

Authors’ contribution. S.S.K., A.K.S. — conceptualization, formal analysis, writing — review and editing, supervision; I.N.M. — methodology, validation, investigation, writing — original draft; G.T.S., R.A.S. — writing — review and editing, supervision.
Funding source. The study had no sponsorship.
Competing interests. The authors declare that there is no conflict of interest in the presented article.

About the authors

Said S. Ksembaev

Kazan State Medical University

Email: ksesa@mail.ru
ORCID iD: 0000-0002-5712-9601
SPIN-code: 7775-0599

MD, Dr. Sci. (Med.), Prof., Head of Depart., Depart. of Maxillofacial Surgery and Surgical Dentistry

Russian Federation, Kazan

Albert K. Salakhov

Kazan State Medical University

Author for correspondence.
Email: albert-salahov@yandex.ru
ORCID iD: 0000-0002-0791-1363
SPIN-code: 2910-8480

MD, Cand. Sci. (Med.), Assoc. Prof., Depart. of Maxillofacial Surgery and Surgical Dentistry

Russian Federation, Kazan

Gulshat T. Saleeva

Kazan State Medical University

Email: gulshat.saleeva@kazangmu.ru
ORCID iD: 0000-0001-9751-0637
SPIN-code: 9140-1093

MD, Dr. Sci. (Med.), Prof., Head of Depart., Depart. of Prosthetic Dentistry

Russian Federation, Kazan

Ildar N. Musin

Kazan National Research Technological University

Email: ildarmusin@mail.ru
ORCID iD: 0000-0003-4516-4183
SPIN-code: 3662-7200

Cand. Sci. (Tech.), Assoc. Prof., Head of the Depart., Depart. of Medical Engineering

Russian Federation, Kazan

Rinat A. Saleev

Kazan State Medical University

Email: rinat.saleev@kazangmu.ru
ORCID iD: 0000-0003-3604-7321
SPIN-code: 6693-0241

MD, Dr. Sci. (Med.), Prof., Depart. of Prosthetic Dentistry

Russian Federation, Kazan

References

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