The electromyographic (EMG) characteristics of masseter, temporalis and sternocleidomastoid (SCM) muscles during maximum voluntary teeth clench were assessed in 27 male and 35 female healthy young adults. Subjects were divided into two groups: (i) 'complete' Angle Class I (bilateral, symmetric canine and molar Class I relationships), and (ii) 'partial' Angle Class I (one to three canine/molar Class I relationships, the remaining relationships were Class II or Class III). On average, standardized muscular symmetry ranged 80.7-87.9%. During maximum voluntary teeth clench, average co-contraction of SCM muscle was 13.7-23.5% of its maximum contraction. On average, all torque coefficients (potential lateral displacing component) were >90%, while all antero-posterior coefficients (relative activities of masseter and temporalis muscles) were >85%. The average integrated areas of the masseter and temporalis EMG potentials over time ranged 87.4-106.8 muV/muV s%. Standardized contractile muscular activities did not differ between 'complete' and 'partial' Angle Class I, and between sexes (two-way analysis of variance). A trend toward a larger intragroup variability in EMG indices was observed in the subjects with 'partial' Angle Class I than in those with 'complete' Angle Class I (significant difference for the temporalis muscle symmetry, P = 0.013, analysis of variance). In conclusion, the presence of a complete or partial Angle occlusal Class I did not seem to influence the standardized contractile activities of masseter, temporalis and SCM muscles during a maximum voluntary clench. Subjects with a 'complete' Angle Class I were somewhat a more homogenous group than subjects with 'partial' Angle Class I.

Individuals with type 2 diabetes mellitus (T2DM) have an increased risk of bone fragility fractures compared to nondiabetic subjects. This increased fracture risk may occur despite normal or even increased values of bone mineral density (BMD), and poor bone quality is suggested to contribute to skeletal fragility in this population. These concepts explain why the only evaluation of BMD could not be considered an adequate tool for evaluating the risk of fracture in the individual T2DM patient. Unfortunately, nowadays, the bone quality could not be reliably evaluated in the routine clinical practice. On the other hand, getting further insight on the pathogenesis of T2DM-related bone fragility could consent to ameliorate both the detection of the patients at risk for fracture and their appropriate treatment. The pathophysiological mechanisms underlying the increased risk of fragility fractures in a T2DM population are complex. Indeed, in T2DM, bone health is negatively affected by several factors, such as inflammatory cytokines, muscle-derived hormones, incretins, hydrogen sulfide (H2S) production and cortisol secretion, peripheral activation, and sensitivity. All these factors may alter bone formation and resorption, collagen formation, and bone marrow adiposity, ultimately leading to reduced bone strength. Additional factors such as hypoglycemia and the consequent increased propensity for falls and the direct effects on bone and mineral metabolism of certain antidiabetic medications may contribute to the increased fracture risk in this population. The purpose of this review is to summarize the literature evidence that faces the pathophysiological mechanisms underlying bone fragility in T2DM patients.

Purposc]. To define reference values for head-cervical range of motion (ROM) in healthy young adults, to assess the effect of sex, and to quantify the separate contribution of other body districts.Methods. Thirty women and 30 men performed maximal head and cervical spine flexion-extension, lateral bending, and axial rotation. Movements were detected using a digital optoelectronic instrument. Maximum headxervical spine and thoracic motions were separated.result.^. Flexion and extension were performed mainly in the sagittal plane. The movement was larger in women (1 36") than in men (130"). During flexion, both sexes moved the head-neck and the thorax in the same direction. During extension, men moved only the headxervical spine, while women moved the two analyzed districts in the opposite dircctions. Lateral bending was nearly symmetric, associated with head-cervical rotation and extension, and larger in women (91") than in men (77"). Adjunctive thoracic motion was limited in the sagittal and frontal planes, but larger in the horizontal plane (opposite motions of about 20'). Head-neck rotation was symmetric, and associated with concomitant movements in both the sagittal and frontal planes. It was larger in women (162") than in men (155O), and performed with limited adjunctive thoracic motions.Conclusirtr~s. The present values can be used as a first group of normative data for head-cervical ROM in young men and women.

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