Electromyographic (EMG) recording of masticatory muscle activity was performed in 9 adult men with unilateral condylar fracture immediately after conservative treatment of the condylar fracture (T0) and 4 (T1) and 8 (T2) months after the trauma. From T0 to T2, maximal voluntary contraction of the anterior and posterior temporal muscles and of the masseter muscle opposite the fracture side (contralateral) increased significantly. Activity in the anterior temporal muscles also rose significantly during natural chewing, whereas the masseter muscles remained at the same level, but activity consistently tended to be strongest contralaterally to the condylar fracture. In addition, there was a tendency from T1 to T2 for natural chewing to take place predominantly on the contralateral side. The most obvious overall changes during the follow-up were shorter and stronger contractions in all muscles during chewing, on the side of the impaired joint. The increase of activity in the anterior temporal muscles during maximal bite and natural chewing, and the occurrence of stronger and shorter contractions during ipsilateral chewing, were interpreted as signs of improved function due to healing and relief of pain from the impaired joint. On the other hand, there was a specific rise of maximal activity only in the contralateral masseter, and during natural chewing, activity was constantly stronger in the same muscle in combination with the tendency of increasing predominance of contralateral strokes. These traits specifically related to the masseter muscles were considered an indication of a permanent functional distortion due to reflex suppression on the fracture side as an after-effect of the injury.

This paper describes the modulation of human deliberately unilateral mastication by trigeminal and extra-trigeminal standardized painful stimuli. Series with 15 s of gum-chewing before induction of pain, during pain and after pain were quantitatively assessed by jaw-closing muscle electromyography (EMG) and kinematics of the lower jaw. Four different painful stimuli were used: cold stimulation of the frontal region, cold stimulation of the dominant hand, capsaicin stimulation of the hard palate, and pressure pain stimulation of the temporomandibular joint (TMJ). Intensity and quality of perceived pain were rated on visual analogue scales (VAS) and McGill's Pain Questionnaires (MPQ). Analysis of the data showed that frontal cold stimulation was the least painful test and was associated with the few^est changes in masticatory function. Cold stimulation of the hand and palatal capsaicin stimulation caused significant increases in peak amplitudes of EMG bursts from all jaw-closing muscles and faster jaw movements w^hereas TMJ pressure pain produced significantly lower peak EMG amplitudes. The present results suggest that nociceptive input from different tissues and even extra-trigeminal regions may modulate trigeminal motor function in selective ways. Thus, clinical observations of changes in masticatory function may not always be due to pain in the orofacial region and therefore do not necessitate orofacial treatment.

The face and the mouth are often considered to be the windows to our general health. Screening and monitoring of young children for healthy growth and development of the jaws and teeth is becoming a standard practice in more and more countries with a national health system/strategy. Such screenings are based on certain formal and informal notions of what a healthy mouth is. Making the ageing population more aware of their mouth and teeth status, and how oral health is connected to a healthy life is being realized increasingly. This article provides a brief overview of what characteristics are used while screening and evaluating the growth and development of a healthy mouth. The article describes the structural aspects of the healthy bony skeleton, temporomandibular joints, masticatory muscles, lips, palate, dental arches, occlusion, teeth, gingiva, periodontal ligament, oral mucosa, tongue, saliva and microbiome. This is followed by discussing the functional aspects of a healthy mouth, and finally commenting on the relation between a healthy mouth and a healthy body.