Eight-week histological analysis on the effect of chitosan on surgically created one-wall intrabony defects in beagle dogs

OBJECTIVE: To evaluate the periodontal tissue regenerative effects of a chitosan/collagen sponge applied to preclinical one-wall intrabony defects surgically created in beagle dogs. MATERIAL AND METHODS: 4 x 4 mm one-wall intrabony defects were surgically created in the bilateral maxillary first and third, and the mandibular second and fourth premolars. The surgical control group received a flap operation only, while the buffer control group was treated afterwards with a phosphate-buffered saline/collagen sponge (CS) and the chitosan group was treated with a chitosan/cs. The subjects were killed 8 weeks after the operation, and a comparative histological examination was performed. RESULTS: The amount of junctional epithelium migration was 2.30+/-1.24 mm in the surgical control group, 1.49+/-1.25 mm in the buffer control group, and 0.26+/-0.59 mm in the chitosan group. A significant difference was exhibited only between the surgical control and the chitosan group (p<0.05). The amount of connective tissue adhesion was 0.68+/-0.60, 1.07+/-0.91, and 0.41+/-0.42 mm in the surgical control, buffer control, and the chitosan group, respectively. The amount of cementum regeneration was 1.42+/-0.49, 1.60+/-0.41, and 3.46+/-0.78 mm in the surgical control, buffer control, and the chitosan group, respectively. A significant difference was seen between the chitosan group and the rest (p<0.01). The amount of alveolar bone regeneration was 1.00+/-0.77, 1.52+/-0.37, and 2.43+/-0.44 mm in the surgical control, buffer control, and the chitosan group, respectively. A significant difference was observed between the chitosan group and the rest (p<0.05). CONCLUSION: The results demonstrate the beneficial effect of the chitosan/cs on the one-wall intrabony defects of beagle dogs. The inhibited apical migration of epithelium and the increase in the amount of new bone and new cementum suggest the potency of chitosan in inducing periodontal tissue regeneration.     

Torsional strength and toughness of nickel-titanium rotary files

Introduction

The aim of this investigation was to compare torsional strength, distortion angle, and toughness of various nickel-titanium (NiTi) rotary files.

Methods

Five NiTi rotary instruments with different cross-sectional geometries were selected: TF and RaCe with equilateral triangle, ProTaper with convex-triangle, ProFile with U-shape, and Mtwo with S-shape. The size 25/.06 taper of TF, RaCe, ProFile, and Mtwo and the ProTaper F1 files were tested, all with the same diameter at D5. A metal mounting block with a cubical hole was constructed in which 5 mm of the file tip was rigidly held in place by filling the mold with a resin composite. The files were subjected to clockwise rotation at 2 rpm in a torsion tester. The torque and angular distortion were monitored until the file failed. The data were compared statistically for the yield and ultimate strengths, plastic hardening period, and toughness.

Results

TF and RaCe had significantly lower yield strength than other systems. TF had a significantly lower ultimate strength than other files, whereas Mtwo showed the greatest. ProFile showed the highest distortion angle at break, followed by TF. ProFile also showed the highest toughness value, whereas TF and RaCe both showed a lower toughness value than the others (P < .05). Fractographic examination revealed typical pattern of torsional fracture for all brands, characterized by circular abrasion marks and skewed dimples near the center of rotation.

Conclusions

Under the limitations of the present study, the 5 tested NiTi rotary files showed a similar mechanical behavior under torsional load, with a period of plastic deformation before actual torsional breakage but with unequal strength and toughness value.     

Living with ‘Hwa-byung’: the psycho-social impact of elder mistreatment on the health and well-being of older people

Objectives: Elder abuse and neglect is an increasing concern that adversely affects the health and well-being of older people in most societies. The purpose of this paper is to describe the psycho-social impact of elder mistreatment on the health and well-being of older Korean people living in New Zealand.

Method: Data were collected from in-depth interviews. The lived experiences of elder abuse and neglect were studied with 10 older people who were, or who had been, mistreated in their family context. To analyse the data collected, a combined analysis approach was employed using traditional code-based techniques and a concept-mapping method.

Results: The findings of the study show that the effects of elder mistreatment were complex and multidimensional. The older persons who were mistreated in family settings experienced a range of emotional, psychological distress and physical symptoms. Many of them identified ‘Hwa-byung’ (literally anger disease) as a health issue associated with suppressed emotions of anger, demoralisation, heat sensation and other somatised symptoms.

Conclusion: Elder abuse and neglect is a traumatic life event that has considerable psycho-social impacts on older people experiencing the problem. It is important to recognise the power of multidimensional challenges caused by elder mistreatment in health and well-being.     

Circadian fluctuations in three types of sensory modules in healthy subjects

This study was designed to observe and compare the circadian fluctuations in tactile sense, joint reposition sense and two-point discrimination in healthy subjects. Twenty-one healthy adult subjects received perceptual ability tests through these three different sensory modules at approximately 9：00, 13：00 and 18：00 in a day. The distribution of ranking for perceptual ability was significantly different among the three different time points in each individual, with highest perceptual ability in the evening compared with noon and morning, in terms of tactile sense and two-point discrimination. These findings suggest that the perceptual ability of healthy subjects fluctuates according to the time points in a day.     

Three-dimensional reconstructed images using multidetector computed tomography in evaluation of the biliary tract

The recent development of multidetector computed tomography (MDCT) and the parallel escalation in the capabilities of the workstation allow the use of high-quality multiplanar and three-dimensional reconstruction images. As a noninvasive technique, MDCT dedicated to the biliary tract represents an alternative to magnetic resonance cholangiography. The usefulness of three-dimensional reconstructed images using MDCT in evaluating biliary tract abnormality is illustrated.     

Bmi1, stem cells, and senescence regulation

Stem cells generate the differentiated cell types within many organs throughout the lifespan of an organism and are thus ultimately responsible for the longevity of multicellular organisms. Therefore, senescence of stem cells must be prevented. Bmi1 is required for the maintenance of adult stem cells in some tissues partly because it represses genes that induce cellular senescence and cell death.