Immediate effects of repetitive wrist extension on grip strength in patients with distal radial fracture.

OBJECTIVE: To evaluate the immediate effect of repetitive wrist extension on grip strength in patients with distal radial fracture. DESIGN: Interventional study. SETTING: Patients who were admitted to a hospital department of occupational therapy. PARTICIPANTS: Consecutive patients with a unilateral distal radial fracture (N=28). INTERVENTION: Each patient was randomly allocated to either the experimental group (n=14) or the control group (n=14). The experimental group performed 30 repetitive wrist extensions with maximal isometric contraction of the extensors of their affected hands during a 6-minute intervention period, whereas the control group did not perform the exercise. MAIN OUTCOME MEASURES: Grip strength was measured just before and after the intervention period. Pain during grip strength measurements was also quantified using the visual analog scale. Wrist extension strength was measured 10 minutes after the grip strength measurement. RESULTS: Grip strength increased immediately after repetitive wrist extension in the experimental group, but it remained the same in the control group. Visual analog scale scores indicated that pain was relieved only in the experimental group. However, pain was unrelated to strength production. CONCLUSIONS: The intervention used in this study might be useful during physical examination to reveal the potential grip strength of patients. The intervention may also be an effective warm-up training procedure in preparation for conventional grip-strengthening exercises.

Influence of oxygen inhibition on the surface free energy and enamel bond strength of self-etch adhesives.

We compared the surface free energies and enamel bond strengths of single-step self-etch adhesives with and without an oxygen-inhibited layer. The adhesives were applied to the enamel surfaces of bovine incisors, light irradiated, and the oxygen-inhibited layer was either retained or removed with ethanol. The surface free energies and their components (γ(S)(LW), γ(S)(+), and γ(S)(-)) were determined by measuring the contact angles of three test liquids placed on the cured adhesives. The enamel bond strengths of specimens with and without the oxygen-inhibited layer were measured. For all surfaces, the value of the estimated surface tension component γ(S)(LW) was relatively constant. The value of the γ(S)(+) component increased slightly when the oxygen-inhibited layer was removed, whereas that of the γ(S)(-) component decreased significantly. The enamel bond strengths of the self-etch adhesives were significantly lower in the specimens without an oxygen-inhibited layer. The oxygen-inhibited layer therefore appeared to promote higher enamel bond strength.

Effects of root morphology on stress distribution at the root apex.

It is thought that the stress concentration at the root apex caused by orthodontic force induces root resorption. The purpose of this study was to investigate stress distribution at the root in cases of deviated root shapes using finite element models (FEMs). To clarify this, five three-dimensional FEMs divided by deviated root shape (normal, short, blunt, bent root apex, pipette shape) were constructed and, experimental orthodontic forces, applied in a vertical (intrusive) and horizontal (lingual) direction to the tooth axis. In the short-root model, significant stress was concentrated at the middle of the root. The blunt-shaped root model showed no significant stress concentration at the root. In the models with a bent or pipette-shaped root, significant stress was concentrated at the root apex. During orthodontic force application, stress concentration was observed in the root of the models with short, bent, and pipette-shaped roots, indicating that attention must be paid to root shape during orthodontic treatment.