Physiology of the Maxillofacial Region

Clinical Significance of the Discipline

The physiology of the maxillofacial region serves as the foundation for all dental specialties. Without knowledge of the normal processes of mastication, swallowing, taste reception, and salivation, the clinician's work is reduced to a set of mechanical actions.

• Gnathology and Orthopedics rely on an understanding of the biomechanics of masticatory muscles and the kinematics of the temporomandibular joint (TMJ).
• Therapeutic Dentistry and Surgery are based on the physiology of salivary secretion (important for caries prevention and the diagnosis of sialadenitis), as well as the hydrodynamic theory of dentin pain. Without knowledge of odontoblast structure, it is impossible to adequately interpret patient complaints and select pain management.
• Orthodontics takes into account the mechanisms of articulation and swallowing, as changes in the shape of dental arches directly affect these functions.

Characteristics of the Oral Cavity in Infancy

In infants, the anatomy and physiology of the oral cavity are adapted for efficiently extracting breast milk. The cheeks with fat pads, gums, lips, and tongue with epithelial villi work as a single coordinated mechanism. Due to the small volume of the stomach and mouth, infants require frequent feedings in small portions.

Early latching triggers crucial physiological processes: the child develops normal microflora and immune defense, while the mother's lactation and uterine contraction are stimulated. In addition, proper areolar grasp during sucking provides the necessary mechanical load on the mandible, stimulating its growth. If an infant is bottle-fed with an improperly selected nipple, milk flows without effort, depriving the jaw of the stimulus for development.

The oral mucosa in infants performs a barrier function, but it is extremely thin. Poor hygiene of care items easily leads to candidal stomatitis (thrush) or aphthous lesions.

Factors Disrupting the Development of the Dentofacial System

The formation of a correct bite is influenced by numerous external and internal conditions at different stages of growth:

1. Early Age (2–3 years): bad habits (sucking fingers, pacifiers), a predominance of soft food in the diet, and a shortened lingual frenulum inhibit jaw development. Incorrect sleeping posture also deforms the bones: for example, a chin pressed against the chest leads to upper teeth being covered by the lower ones, while a hand placed under the cheek causes jaw asymmetry.
2. Preschool Age (3–6 years): disorders of swallowing and chewing are critical. Normally, during swallowing, the teeth are clenched, the lips are closed, and the tongue rests against the anterior part of the hard palate. If the tongue is thrust between the teeth, excessive tension of the tissues around the mouth occurs. Unilateral chewing at this age provokes TMJ pathologies.
3. School Age (7–13 years): posture disorders, macroglossia, caries complications, and even playing musical instruments begin to affect the bite (the violin can provoke a crossbite, and wind instruments an open bite).

Physiologic Bite and Pathologies of Facial Nerves

Physiologic Bite (occlusion) is characterized by the coincidence of the habitual and central positions of the mandible. At the same time, the articular head is located at the base of the articular tubercle slope, and the masticatory muscles work symmetrically on the right and left sides.

When diagnosing diseases of the maxillofacial region, it is important to distinguish nerve lesions:

• Trigeminal Neuralgia: manifests as strict attacks of pain (paroxysms). It often has to be differentiated from pulpitis, periodontitis, alveolitis, or sinusitis.
• Neuropathy: damage to the nerve trunk itself, in which the pain is constant and often accompanied by functional deficits.
• Facial Nerve Lesion: since the nerve is mixed, facial expression, sensation, and secretion may be impaired. Analgesics are not the primary therapy here and are used only as symptomatic agents when pain is present.

For accurate diagnosis, electromyography (assessment of the bioelectrical activity of muscles), odontometry (testing pulp vitality), and masticaciography (recording jaw movements during chewing) are used.

Class and exam questions

What else to study on this topic

• Biomechanics of Masticatory Muscles and Kinematics of the Temporomandibular Joint
• Hydrodynamic Theory of Dentin Pain and Pulp Innervation
• Differential Diagnosis of Trigeminal Neuralgia and Dental Diseases
• Instrumental Research Methods: Electromyography, Odontometry, and Masticaciography
• Impact of Posture and Bad Habits on the Development of Malocclusions

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.