Anat Gavish

Effect of Controlled Masticatory Exercise on Pain and Muscle Performance in Myofascial Pain Patients: A Pilot Study

Abstract The aim of this study was to test the hypothesis that strengthening masticatory muscles using a controlled chewing exercise protocol improves muscle function, as evaluated quantitatively by electromyogram, and reduces pain at rest and during function. The study included 20 patients diagnosed with myofascial pain according to the Research Diagnostic Criteria for Temporomandibular Disorders with low masseter volume increase during maximal clench. The exercise group (ten patients) was subjected to a controlled gum chewing exercise protocol for eight weeks: the control group (ten patients) received only support and encouragement. Patients were examined at the beginning and at the end of the experiment which included an electromyogram (EMG) to assess muscle performance, masticatory muscle tenderness to palpation, mouth opening range, subjective anamnestic indices to evaluate pain perception and pain relief, and chewing tests. The EMG showed that the masticatory muscle exercise did produce objective physiologic results. In the exercise group, a significant increase was found in the electric muscle activity of the masseters during maximal voluntary clench (p=0.007). The exercise group showed significant reduction in pain during rest, pain during the chewing test, and a disability score. At the end of the study, a difference between the two groups was shown in the Pain Relief Scale: significantly greater pain relief was found in the exercise group as compared to the control group (p=0.019). For all other clinical parameters, there was no difference between the two groups or interaction between time and treatment. The results of this study seem to be equivocal. Additional experiments on larger population groups with extended chewing protocols are necessary before a more substantial conclusion can be reached.

Age-associated changes of the mandibular foramen position in anteroposterior dimension and of the mandibular angle in dry human mandibles.

The effect of age on the anteroposterior (A‐P) position of the mandibular foramen (MF) and on the size of the gonial angle (GA) was evaluated in this study. From an Israeli Bedouin population, 121 dry mandibles with primary (36), mixed (26), and permanent dentitions (59) were analyzed. The A‐P position of the MF perpendicular to the posterior border of the ramus was measured with a digital caliper. A mandibulometer was used to evaluate the GA. The MF distance from the posterior border of the ramus increased significantly with age by 66% from primary (7.75 mm) to permanent (12.9 mm; P < 0.001). Similarly, the MF distance from the posterior border of the ramus relative to the total ramus width in A‐P dimension increased significantly (21.4%) with altered dentitions from primary (0.28) to late permanent dentition (0.34; P < 0.001). The GA decreased significantly with age from 140.17° ± 5.9° (primary dentition) to 123.61° ± 6.9° (late permanent dentition; P < 0.001). The anterior movement of the MF and the decreased size of the GA that occurred with changing dentition were related to growth process. The MF moves anteriorly, and the GA decreases with age. Anat Rec, 2011.

Splints and stress transmission to teeth: an in vitro experiment

OBJECTIVE To determine the influence of hard and soft splints with two thicknesses on the stress transmission to the tooth supporting the splint and the opposite tooth. METHODS Continuous vertical forces up to 500N were applied to two opposite first molar phantom teeth using a universal loading machine. Deformation was detected by strain gauges attached to the cervical area of the buccal and lingual aspects of the lower tooth. Strain, as a function of force, was collected and the slope, defined as the compliance (in microS/N) of the system, was calculated. RESULTS The highest compliance was found with hard splints. When splints were constructed on the upper molar, the highest compressive compliance was registered on the buccal side (2.8 microS/N) and tension compliance on the lingual side (-0.35 microS/N). When constructed on the lower tooth, the opposite was found. Soft splints resulted in compression on both the buccal and lingual sides when adjusted to the upper or lower tooth. A higher compliance was found on the buccal side (1.26 microS/N), while on the lingual side, the values varied (0.48-0.78 microS/N). CONCLUSIONS Soft splints are more efficient in protecting teeth against the damage of bending forces although there is an increase of compression forces. The tooth opposing a hard splint is exposed to a higher risk of bending forces.