Antti Waltimo

Maximal bite force and its association with signs and symptoms of craniomandibular disorders in young Finnish non-patients

Maximal bite force values and subjective symptoms and clinical signs of craniomandibular disorders (CMD) were recorded for a non-patient sample of 129 young adults, 56 men and 73 women. The signs and symptoms of CMD were classified on the basis of Helkimos clinical dysfunction index. The two genders reported equally frequently subjective symptoms of CMD, but women had significantly more severe clinical signs of CMD than did men. Mean maximal bite force values for men were 909 N (SD, 177) in the molar region and 382 N (SD, 133) in the incisal region and thus significantly higher than corresponding figures for women, 777 N (SD, 168) in the molar, 325 N (SD, 116) in the incisal region, suggesting that separate evaluation of the genders would be advisable in future studies involving bite force assessments. Neither subjective symptoms nor clinical signs of CMD correlated significantly with maximal bite force values. The bite force values measured were in line with theoretical calculations.

Does clicking in adolescence lead to painful temporomandibular joint locking

BACKGROUND It has been assumed that clicking of the temporomandibular joint (TMJ) may predispose to closed locking. Although jaw clicking is a common complaint, locking of the TMJ is rare. METHODS To assess whether clicking is a reliable predictor of locking, we examined longitudinally over 9 years the variation of reported and recorded TMJ clicking in 128 young Finnish adults. Subjects were interviewed and examined at the ages of 14, 15, 18, and 23 years. FINDINGS Reported and recorded TMJ clicking both increased significantly with age, varying from 11% to 31% and from 11% to 34%, respectively, However, clicking showed no predictable pattern, and only a few subjects consistently reported clicking (2%) or had it recorded (2%). None developed locking. INTERPRETATION Because none of the young adults developed locking of the TMJ, we suggest treatment for clicking should be conservative.

Differential Effects of Noxious Conditioning Stimulation of the Cheek by Capsaicin on Human Sensory and Inhibitory Masseter Reflex Responses Evoked by Tooth Pulp Stimulation

In this study, we investigated whether selective activation of nociceptive primary afferent fibers by capsaicin would induce modulations on tooth-pulp-evoked sensory or inhibitory masseter reflex responses in healthy human subjects. The contribution of central N-methyl-D-aspartate (NMDA) receptor mechanisms in capsaicin-induced effects on sensory or reflex responses was evaluated by dextromethorphan, an NMDA-receptor antagonist. The inhibitory masseter reflex was evoked by electrical stimulation (constant current, single pulses) of the upper incisor while the subject was biting at 10% of his maximal force. The sensation of the tooth pulp stimulation was evaluated by visual analogue scale (VAS). The magnitude, duration, and the latency of the reflex were determined by bite force measurements. The inhibitory masseter reflex could be induced by non-painful tooth pulp stimulation, and the inhibition was enhanced as a function of increasing stimulus intensity. Capsaicin (1%) applied topically to the skin of the cheek produced a spontaneous burning pain sensation. During capsaicin treatment, the VAS ratings for the sensation induced by tooth pulp stimulation were significantly reduced, whereas no significant changes were found in the tooth-pulp-induced masseter reflex responses. Double-blind treatment with dextromethorphan at a dose of 100 mg (= the highest dose without side-effects) had no effect on sensory or reflex responses. These data indicate that noxious stimulation of the facial skin by capsaicin induces differential effects on tooth-pulp-evoked sensory and inhibitory masseter reflex responses: Sensory responses are strongly attenuated, while masseter reflex responses are not significantly changed. Dextromethorphan at a clinically applicable dose does not influence tooth-pulp-evoked sensory or reflex responses or their modulation by capsaicin. Furthermore, the lack of modulation of the masseter reflex response by capsaicin differs from the capsaicin-induced enhancement of a nocifensive limb flexion reflex described earlier.

Tooth wear in maxillary anterior teeth from 14 to 23 years of age

Using a planimetric method, the size of horizontal wear facets on maxillary anterior teeth was studied longitudinally in the permanent dentition of 35 subjects at ages 14, 18, and 23 years. The study subjects had not previously undergone any orthodontic treatment and had Class I occlusion. We studied the association between the amount of wear and reported parafunctions and maximal bite force. Total wear areas in age groups 14, 18, and 23 years were 29.5 mm2 (SD 11.4), 39.1 mm2 (SD 12.7), and 45.0 mm2 (SD 13.0), respectively. The total wear area increased significantly both from 14 to 18 years of age and from 18 to 23 years of age (p<0.0001). Between 18 and 23 years of age, the maxillary canines showed strongest wear, although the central incisors had largest wear facets. It can be concluded that wear of permanent anterior teeth is a continuous phenomenon in adolescence and young adulthood.

Altered control of submaximal bite force during bruxism in humans

Abstract The control of bite force during varying submaximal loads was examined in patients suffering from bruxism compared to healthy humans not showing these symptoms. The subjects raised a bar (preload) with their incisor teeth and held it between their upper and lower incisors using the minimal bite force required to keep the bar in a horizontal position. Further loading was added during the preload phase. A sham load was also used. Depending on the session, the teeth were loaded by the experimenter or the subject and in one session the subject did not see the load (no visual feedback). The bite force was measured continuously using a calibrated force transducer. In all the subjects, the bite force increased with increasing load. Following the addition of the load, the level of the tonic bite force was reached rapidly with no marked overshoot. The patients with bruxism used significantly higher bite forces to hold the submaximal loads compared to the control subjects. In the control subjects, the holding forces for each submaximal load were identical in the men and the women and were independent of subject maximal bite force. Sham loading evoked no marked responses in biting force. Whether the subject or the experimenter added the load or whether the subject had visual feedback or not were not significant factors in determining the level of bite force. The results indicated that the patients with bruxism used excessively large biting forces for each given submaximal load. This study showed no evidence that the inappropriate control of bite force by patients with bruxism was due to an abnormality in the higher cortical circuits that regulates the function of trigeminal motoneurons in the brainstem. This was shown by a lack of abnormality in coordination of voluntary hand movement with biting force, a lack of abnormal anticipation response to a sham load and a lack of any effect of visual feedback. The results were in line with the hypothesis that afferent input from oral (periodontal or masticatory muscle) tissues does not provide an appropriate control of motor command in bruxism.