Optimization of paeonol-loaded microparticle formulation by response surface methodology.

In this study, a central composite rotatable design based on response surface methodology (RSM) was employed to design and formulate an appropriate paeonol microparticle formulation. Five levels of a three-factor, rotatable, central composite design were used to evaluate the critical formulation variables. The optimum conditions for preparing paeonol-loaded microparticles were predicted to be: polyvinyl alcohol (PVA) content (2.84%), the ratio of drug to polymer (6.88) and the stirring rate (1007.59 rpm). The optimized responses for production yield and loading efficiency were found to be 68.86% and 55.90%, respectively, and the particle size were 23.27 ± 0.76 µm and the sorting coefficient (σ) was 0.732. Furthermore, in vitro release study suggested that microparticle could be a suitable delivery system in treating skin disease for its sustained release of drug. In conclusion, RSM can be successfully used to optimize the effect of formulation variables.

Characteristics of temporomandibular joint vibrations in anterior disk displacement with reduction in adults.

The objective to the present study was to compare temporomandibular joint (TMJ) vibration in anterior disk displacement with reduction (ADDWR) in adults and to explore the diagnostic value of frequency spectrography of TMJ vibrations. Twenty-one patients with ADDWR formed the case group and were further divided into three subgroups according to the degree of disk displacement, and 26 symptomless adults formed the control group. The joint vibration was recorded during rhythmic maximal open-close jaw movement using JVA/JT, BioPAK (Bioresearch, Inc., Brown Deer, WI)). The sensitivity and specificity of the total integral for diagnosis of ADDWR was calculated. All TMJ vibration parameters, including total integral, integral>300Hz, integral<300Hz, >300/<300 ratio, peak amplitude, peak and median frequencies of the case group were significantly higher than that of the control group. Along with the degree of disk displacement, the amplitude and frequency of TMJ vibrations increased, and the total integral significantly increased. The total integral demonstrated high sensitivity and specificity for diagnosis of ADDWR (85.7% and 84.6%, respectively). TMJ vibration was significantly higher in adults with ADDWR than that in the symptomless control group. Different pathological stages of disk displacement have different TMJ vibrations.

[The characteristics of masticatory muscle activity in bruxers].

OBJECTIVE: To evaluate the effects of bruxism on masticatory muscle electromyographic (EMG) activity. METHODS: Twenty-four bruxers and sixteen asymptomatic control subjects were included through questionnaire and clinical examination. EMG activity was recorded by placing surface electrodes on bilateral anterior temporalis (TA), masseters (MM), anterior digastrics (DA) and sternocleidomastoid (SCM) muscles. EMG activities at rest, during maximal voluntary clenching in intercuspal position and swallowing were recorded by means of Bio PAK system. RESULTS: EMG activities of TA and MM at rest were significantly higher in bruxism group than in control group (P<0.05). When subjects clenched their teeth in intercuspal position, the activities of TA and MM were much lower in bruxism group than in control one (P<0.05). EMG activity during swallowing was no significant difference between the two groups. The asymmetry index of bilateral TA and MM in bruxism group was a little higher than the control group, but there was no significant difference between the two groups (P>0.05). CONCLUSION: Masticatory muscle dysfunction of bruxers is mainly represented as higher potential in postural position and lower potential during maximal voluntary clenching in intercuspal position of anterior temporalis and masseters.