22 The more posteriorly the transducer is placed in the dental arch, the greater the bite force.63 It has been explained by the mechanical lever system of the jaw.4,21 In addition, selleck products greater bite force can be tolerated better in posterior teeth, because of the larger area and periodontal ligament around posterior teeth roots.63 Indeed, different positions of the transducer in dental arch may influence the different muscles that are involved in force production. If the transducer is placed anteriorly between the incisor teeth, with a resultant mandibular protrusion, the masseter muscle will produce most of the force together with the medial pterygoid muscle. If the bite force transducer is more posteriorly placed, then anterior fibres of the temporalis muscle will become more active and hence make a greater contribution to the effort.

63 Unilateral and bilateral measurements Another factor influencing the value of the bite force is the recording side involved: unilateral or bilateral application. Most of the studies have shown that bite force during bilateral clenching is larger than during unilateral clenching.6,15,16,38 Bakke et al15 have applied conventional force transducers in healthy subjects during both unilateral and bilateral clenching. Bilateral total bite force has been measured in healthy subjects and found to be 40% larger than unilateral clenching on just one force transducer. Shinogaya et al16 have compared bilateral and unilateral bite force measurements using different transducers. They have employed a pressure-sensitive foil (0.

1 mm thick) for bilateral clenching and a conventional force transducer (6�C7 mm thick) for unilateral clenching. They have concluded that bite force increased by about 100% and masseter activity increased by about 50% during bilateral clenching compared to unilateral clenching. Van Der Bilt et al6 have measured bite force and jaw muscle activity during bilateral and unilateral maximum clenching and found 30% larger bilaterally measured bite force using strain-gage transducer. Moreover, activities of both right and left masseter and anterior temporal muscles have been reported as 30% larger in bilateral measurement than unilateral measurement. They have pointed out that masseter muscles�� activity showed no significant differences in the unilateral clenching experiments; however, the activities of right and left temporal muscles differed significantly during unilateral clenching: loaded side showed significantly more muscle activity.

Theoretically, the jaw muscles should be able to generate a unilateral bite force equal to the force obtained during bilateral clenching. The force per side is larger when measured unilaterally, compared with half of the force measured bilaterally. The lower jaw muscle activity and bite force obtained during unilateral clenching as compared GSK-3 to bilateral clenching may be a result of inhibition by periodontal and joint receptors.