Surface electromyography (EMG) has been widely used in clinical dentistry, although interpretation of the raw data is difficult owing to its low reproducibility. Linear EMG envelopes, also known as EMG profiles, which are normalized with respect to raw EMG amplitudes and stride, have been developed to analyze the time course of gait stride. Normalized EMG contraction patterns can be used for comparing individuals or recording sessions on the same individual made at different times.
We made EMG profiles during unilateral gum chewing for the masticatory muscles of five asymptomatic volunteers. EMG signals were recorded from the anterior temporal (Ta), masseter (M) and anterior belly of the digastric (Da) muscles on the subject's preferred chewing side. The mandibular kinesiograph was used for tracking incisal point movement during chewing. EMGs and kinesiometric data were simultaneously recorded for 90 seconds. Ensemble averages of EMG profiles were made from 10 stable strokes after 60 seconds of initiation of chewing. Phasic characteristics of the EMG profiles were evaluated by product-moment correlation and intraclass correlation coefficients. Although the EMG profiles for Ta and M were very similar, those for Da were different from the elevator muscles.

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Bone morphogenetic protein (BMP) has the capability of 1) inducing bone formation in non-bone tissue such as muscle, 2) promoting proliferation and differentiation of human dental pulpal cells, and 3) inducing early formation of both osteodentin and regular tubular dentin. In addition, when BMP is implanted in periodontal defects, it stimulates regeneration of periodontal tissues. In the present study, we sought to explore the mechanisms by which BMP induces these effects, using immunohistochemical methods to investigate periodontal fibroblast-like cells in vitro. Cellular production of fibronectin, endogenous BMP and alkaline phosphatase were measured using image analysis of immunohistochemical reactivity. Periodontal fibroblast-like cells incubated with exogenous BMP showed decreased alkaline phosphatase activity, unchanged fibronectin production, but increased expression of endogenous BMP compared with control specimens incubated without BMP. These data suggest that regenerative as well as inductive effects of BMP on undifferentiated periodontal mesenchymal cells may be mediated through its ability to modulate cellular expression of these substances.

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Various amplitude normalization procedures for surface electromyographic (EMG) signals have been utilized to reduce the inter- and intrasubject variability of data collected on gait analysis. We examined two normalization methods (normalization to mean of ensemble average: NME, and normalization to peak of ensemble average: NPE) for intersubject variability and reproducibility surface EMG profiles for the masticatory muscles during unilateral gum chewing. The EMG profiles for the anterior temporal (Ta), posterior temporal (Tp), masseter (M) and anterior belly of the digastric (Da) muscles on the chewing side from five normal subjects were made at three different sessions. Coefficients of variation and intraclass correlation coefficients were used to assess variability and reproducibility. Each normalization procedure the intersubject variability of unnormalized EMG profiles for Ta, Tp and M. The NME procedure provided lower intersubject variability for Da. The reproducibility of unnormalized profiles for Ta, Tp and M was significantly improved by both procedures (p<0.05). NME on Da was more effective in its reproducibility (p<0.05). We found that the phasic characteristics of muscular activity influenced the outcome of amplitude normalization.

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Bone morphogenetic protein (BMP) refers to a group of bone-inducing growth factors used to enhance experimental osseous repair. Previous studies have indicated that BMP promotes the proliferation and differentiation of fibroblasts from human dental pulp both in vitro and in vivo. Furthermore, when BMP is used as a pulp capping agent, it has ability to induce the formation of both osteodentin and tubular dentin. In this study, we sought to explore whether or not BMP, complexed to ceramic dentin (BMP/CD), would constitute a more effective pulp capping agent than BMP alone.
Experimental pulp exposures were created in dogs, and BMP/CD was placed on the surface of the exposed dental pulp. The inductive effect of such stimulation on reparative dentin formation was observed morphologically. Results showed that two weeks after exposure, some osteodentinal matrix was formed in the space surrounding the implanted BMP/CD particles while the remainder of the space was occupied by proliferating fibroblasts. At 4 weeks postoperatively, the dentinal bridge was complete. When ceramic dentin without BMP was used, there was minimal bone-like matrix formed even at 4 weeks postoperatively. These results suggest that the BMP/CD complex is effective as a stimulant of reparative dentin formation and shows potential as a therapeutically useful pulp-capping agent in a clinical setting.

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