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The masticatory muscles differ in their fiber type composition. It can therefore be expected that their electromyographic (EMG) power spectra will differ during the performance of different bite force tasks. In the present study, surface EMG activity was picked up from the masseter and from the anterior and posterior temporalis muscles of nine adult subjects. At a bite force level as low as 25 N, the mean power frequency (MPF) values of the posterior temporalis were significantly lower than those of the masseter and anterior temporalis. The MPF values of the masseter muscles decreased with an increase of bite force magnitude, whereas the MPF values of the anterior and posterior temporalis did not change significantly. The MPF values were significantly influenced by the direction of bite force. The observed changes of MPF are possibly related to the recruitment of different fiber types, and support the concept that the masticatory muscles behave heterogeneously.

The aim of this report is to illustrate the case of a patient whose myofascial pain syndrome was misdiagnosed as odontogenic pain, and who was treated using irreversible dental procedures. Even if dental pain commonly has an odontogenic etiology, it is also possible that pain arising from different orofacial sites such as jaw muscles, maxillary sinus, or nervous structures can be referred to the teeth. When the etiology of a dental pain condition cannot be clearly identified, it is necessary to consider all possible causes of dental pain, which may also be nonodontogenic. The need for comprehensive examination and careful diagnosis before irreversible dental treatment is emphasized.

Recent evidence suggests that evaluation of muscle tenderness in temporomandibular disorders (TMDs) patients might be improved by the use of pressure algometry; nevertheless, the evaluation of the diagnostic value of this tool has received little attention. The aim of this study was to assess the diagnostic value of pressure algometry in myofascial pain of the jaw muscles, by calculation of sensitivity (Se), specificity (Sp) and positive predictive values (PPV). Pressure pain thresholds (PPTs) of masseter and anterior temporalis muscles were assessed in 40 female myogenous TMD patients and 40 age-matched female controls. PPTs were significantly lower (P

The aim of this study was to evaluate the short-term effects of orthodontic pain on the pressure pain threshold (PPT) of the masseter and anterior temporalis muscles, and on their electromyographic (EMG) activity during clenching and chewing. Orthodontic pain was induced in 14 healthy subjects (mean age 26.6, SEM 1.1) by placing orthodontic separators. The subjects were randomly assigned to an experimental and to a control session in a double-blind crossover study. PPT was significantly reduced (Student's t-test; P < 0.001) after experimental sessions for both the masseter and the anterior temporalis muscles, whereas no significant differences were found during control sessions (P > 0.05). EMG activity during clenching and chewing was significantly reduced (0.001 less than or equal to P < 0.05) after experimental sessions for both masseter and anterior temporalis muscles, whereas no significant differences were found during control sessions (P > 0.05). The decrease of PPT found in this study can be related to the occurrence of muscle pain and headache reported by patients during orthodontic or other dental treatment. The decrease of EMG activity of the jaw muscles associated with orthodontic pain is consistent with the pain adaptation model and should be considered as a potential factor for loss of occlusal anchorage during orthodontic treatment.

The anatomical basis of dentistry, 3rd edn (2010) Author: Bernard Liebgott. Publisher: Mosby, Elsevier, Kidlington, Oxford, UK Price: £58.00 ISBN: 978-0-323-06807-9 This glossy book of 510 pages covers the complete anatomy of the human body in 11 well-presented chapters. Four of them are dedicated to the anatomy of the head and neck, while the remaining chapters cover a wide range of …

Orofacial pain is one the main reasons for patients to seek treatment. Pain in the face and mouth has a significant psychological meaning since a good interplay of orofacial structures is essential for correct jaw function, communication and body image. Unfortunately, diagnosis and treatment of orofacial pain is not an easy task. This textbook represents a good start for those interested in orofacial pain conditions. It is an extended revision of Dr Welden Bell's classic text, reporting the latest findings related to pain supported by an updated text including …

The masticatory muscles differ in their fibre type composition. It can therefore be expected that their electromyographic (EMG) power spectra will differ during the performance of different bite force tasks. In the present study surface EMG activity was picked up from the masseter, and anterior and posterior temporalis muscles of nine adult subjects. Direction and magnitude of bite force were recorded using a three-component force transducer. Bite forces were exerted in five different directions: vertical, forward, backward, to the right and to the left of the subject. Non-vertical forces were kept at an angle of 15° from the vertical. Force levels of 25, 50, 100 and 200 N were exerted in each of the investigated directions. Data collected were analysed by means of a regression model for repeated measurements. It appeared that the mean power frequency (MPF) values of the posterior temporalis were significantly lower (P 0·05). The MPF values were significantly influenced by the direction of bite force (P

The aim of the present study was to compare the efficacy of physiotherapy and counselling for the treatment of myofascial pain of the jaw muscles. Sixty-three consecutive myogenous TMD patients, diagnosed according to the RDC-TMD criteria, were assigned to two treatment groups with a balanced-block randomization. The first group received only counselling with general information about self-care of jaw musculature. The second group received the same general information supplemented by self-massage, application of moist heating pads and stretching exercises of the masticatory muscles. Treatment success was decided on treatment contrast (TC), based on relative changes of sufficiently large anamnestic and clinical scores (van der Glas and van Grootel, 2000). Additional measurements included pressure pain threshold (PPT) of the masseter, anterior temporalis and Achilles' tendon, pain during gum chewing and spontaneous muscle pain scores rated on visual analogue scales (VAS). Data were collected at baseline and 3 months after start of treatment. Mann–Whitney's test and Fisher's exact test were used for statistical analysis. Sixteen patients dropped out from the study: eight from the counselling and eight from the physiotherapy group. The success rate was 13 of 23 (57%) patients for counselling and 18 of 24 (75%) for the physiotherapy group (P > 0·05). There was no significant difference between groups in all the other variables. Over a short-term period, physiotherapy, as used in this protocol, does not appear superior to counselling for the treatment of TMD myofascial pain.

It is generally recognized that psychological factors play an important role in chronic orofacial pain patients. This study analysed psychological profiles of chronic pain patients affected with temporomandibular disorders (TMD), by means of the Minnesota Multiphasic Personality Inventory (MMPI) test. Fifty consecutive TMD patients were examined and were then divided into two subgroups: 1. myofascial pain and 2. temporomandibular joint articular disorders. Sixty-two percent of the whole sample presented pathological MMPI scores. Both subgroups presented similar profiles with alteration of the neurotic triad (hypochondriasis, depression, hysteria), and pathological values of hypochondriasis and hysteria ("V" configuration). Since the personality profile did not differ between the two subgroups investigated, it was not dependent on the dysfunctional origin of the pathology (myalgia or primary TMJ pathology). Chronic TMD patients presented personality characteristics similar to those of other chronic pain patients according to the MMPI.

A case report of a Class I malocclusion with a severe skeletal open bite, excessive overjet, a high mandibular plane angle, and a forward maxillary rotation is presented. Treatment has eliminated the causative factors (i.e., mouth breathing, enamel hypoplasia of the first molars, and abnormal tongue posture and function). A normal growth pattern has been restored, ensuring a good and stable orthodontic result.