Experimental noxious stimulation of the right masseter muscle does not affect bilateral masseter and temporalis muscle activity and force parameters during standardised isometric biting tasks.

Aim: To determine if the electromyographic (EMG) activity of the left and right masseter and anterior temporalis muscles is altered by experimental right masseter muscle noxious stimulation during goal-directed isometric biting tasks in asymptomatic humans.

Methods: Isometric biting tasks (slow and fast ramp biting tasks, 2-step biting task) were performed on an intraoral force transducer in 18 participants during the following blocks: baseline block, hypertonic saline infusion into the right masseter muscle (painful block) and isotonic saline infusion into the right masseter (control block). Bipolar surface electrodes recorded EMG activity from the bilateral masseter and anterior temporalis muscles.

Proteolytic roles of matrix metalloproteinase (MMP)-13 during progression of chronic periodontitis: initial evidence for MMP-13/MMP-9 activation cascade.

Aim: Matrix metalloproteinases (MMP)-13 can initiate bone resorption and activate proMMP-9 in vitro, and both these MMPs have been widely implicated in tissue destruction associated with chronic periodontitis. We studied whether MMP-13 activity and TIMP-1 levels in gingival crevicular fluid (GCF) associated with progression of chronic periodontitis assessed clinically and by measuring carboxy-terminal telopeptide of collagen I (ICTP) levels. We additionally addressed whether MMP-13 could potentiate gelatinase activation in diseased gingival tissue.