Evaluation of the effectiveness of intermittent mechanical pressure with short loading duration: new type of intermittent force for orthodontic treatment.

Background: Since it is difficult to precisely control the magnitude of force in orthodontic practice, controlling the duration of force is expected to prevent tissue damage. The use of an actuator as an appliance for intermittent force application is a possible solution for controlling the duration. However, effectiveness of an actuator for controlling the duration is still not clear. Aim: To determine whether a short loading duration of intermittent force has the potential to maintain a sound condition of the capillaries and induce dilation of capillaries, which is a requisite phenomenon for orthodontic tooth movement. Materials and methods: Six-week-old male hamsters with a dorsal skinfold chamber attached to an intermittent loading device were used. In three experimental groups, application of intermittent pressure that involved repetition of loading and unloading was performed. The durations of loading/unloading were 1 second/9 seconds (group T10), 1 second/19 seconds (group T20), and 1 second/29 seconds (group T30). Vessels were examined using a fluorescence microscope and a stereomicroscope for 5 days. Results: Widths of capillaries in groups T10 and T20 increased significantly (P < 0.01). In contrast, widths of capillaries in group T30 showed no significant difference from those in the control group. Only group T10 showed bleeding, obvious destruction of vessels, and a significant increase in the rate of disappearance of vessels. Conclusion: In the epidermis, although conditions are limited, a short loading duration of intermittent force maintains a sound condition of the capillaries at the tissue level and induces dilation of capillaries.

Synthesis and evaluation of fluorescent resins with europium-ß-diketonate complex for orthodontic use.

No effective technique exists for removing adhesive remnants following bracket debonding. We propose that fluorescence imaging using europium ions (Eu3+) offers an effective solution for minimizing iatrogenic enamel damage. This study aimed to assess the impact of different mixing ratios of monomer mixtures on the photoluminescence and flexural properties of a newly developed fluorescent adhesive. Four monomer blends with varying urethane dimethacrylate (UDMA) to triethylene glycol dimethacrylate (TEGDMA) ratios were prepared and polymerized. The blends contained 0.1 wt% of tris(1,3-diphenyl-1,3-propanedionato)(1,10-phenanthroline) Eu(III), [Eu(DBM)3Phen], as the phosphor. Optical measurements and flexural tests were conducted for each resin specimen. The emission spectra exhibited narrow bands corresponding to the 4f-4f transitions of the Eu3+ ions. The photoluminescence properties remained unaffected by the mixing ratio, whereas the mechanical properties tended to improve with higher UDMA content. We conclude that the Eu(DBM)3Phen-containing resin shows promise as a fluorescent orthodontic adhesive that contributes to preserving enamel health.