An accurate evaluation of stress corrosion cracking (SCC) in 13Cr martensitic stainless steel (MSS) is still missing due to the lack of an in-situ insight into the process evolution and full characterization of the corrosion morphology. In this work, two main regimes involved in the SCC progression, including localized corrosion and cracking, were comparatively studied using in-situ acoustic emission (AE) monitoring and three-dimensional (3D) X-ray computed tomography (XCT) scanning. The stress corrosion tests were conducted with u-bent smooth specimens subjected to a single droplet of 1 μL 1% neutral NaCl solution. Localized corrosion and cracking evolution were controlled in tempered and quenched steel specimens, respectively. From XCT scanning, localized corrosion was featured by an irregular corrosion pit with deposited corrosion products containing cracks. The single dominant SCC crack was observed to initiate from corrosion pit and propagate with a 3D tortuous and discontinuous morphology. AE signals were detected in both cases. Correlated with in-situ observations and clustering analysis, source identification of AE signals was proposed. AE signals during localized corrosion were assessed to be mainly from cracking within the deposited corrosion products. Comparatively, hydrogen-bubble evolution, plastic deformation, and crack-branches coalescence were proposed as the AE sources of cracking evolution.

BACKGROUND: Superficial nail abnormalities include conditions which produce nail surface changes such as trachyonychia, pitting and ridging. Mostly, this is a neglected area due to the dearth of treatment options. Glycolic acid peeling has been reported to be effective in such cases.
OBJECTIVE: This study aims to assess the safety and efficacy of medium depth peels (70% glycolic acid versus phenol combination peel [8% phenol with 15% trichloroacetic acid]) in patients with superficial nail abnormalities.
METHODS: A right-left comparative study in patients with superficial nail abnormalities was done. On the right finger or toenails phenol combination peels and on the left side 70% glycolic acid was used in a predefined protocol over 12 weeks. The severity was assessed objectively by a new devised index (Nail Surface abnormality Index (NSI]). Patient\'s subjective perception of severity was assessed by Visual Analogue Scale (VAS), and that of the physician was assessed by Physician\'s Global Assessment (PGA) scores.
RESULTS: A total of 17 patients were enrolled, two dropped out and 15 patients were included in the final analysis (mean age 19.2 years, total 120 nails treated). The mean NSI score declined from 7.88 ± 0.45 to 4.02 ± 0.45 on the right side; and from 8.0 ± 0.45 to 4.32 ± 0.44 on left side, at the end of 12 weeks. The VAS declined from 6.57 ± 0.26 to 3.87 ± 0.33 on right side and from 6.32 ± 0.28 to 3.78 ± 0.32 on left side. According to PGA score, five patients showed good improvement, seven showed moderate improvement and three responded poorly.
CONCLUSIONS: Both the medium depth peels were found to be safe and equally efficacious modalities for treatment of superficial nail abnormalities.

BACKGROUND: Fluorosis is a condition resulting from excessive ingestion of fluoride during early childhood leading to the formation of defective enamel. The increased fluoride content is thought to result in a metabolic alteration of ameloblasts, which results in defective matrix, and improper calcification of teeth.
METHODS: A total of 6244 patients between the ages of 6yrs to 60yrs, who presented to our outpatient clinic from October 2009 to December 2010 were included in the study. The study subjects were grouped according to their age into the following groups- 6-14 yrs, 15-25 yrs, 26-40 yrs, and 40-60yrs. Only permanent dentition was taken into consideration in this study.
RESULTS: The overall prevalence of fluorosis in this study was 63.34% (3955 of 6244 patients). Men had a slightly higher prevalence of 64.27% compared to 62.28% among women.
CONCLUSIONS: Prevention of fluorosis would require efforts at raising awareness among the people about the harmful effects of their dietary choices on their teeth. They also need to be educated about adequate and proper oral hygiene, such as brushing their teeth at least two times daily. How to cite this article: Sunil T K L, Shetty S, Annapoorna B M, Pujari S C, Reddy P S, Nandlal B. A Pioneering Study of Dental Fluorosis in the Libyan Population. J Int Oral Health 2013; 5(3):67-72.

OBJECTIVE: To evaluate the surface alterations seen in four kinds of Nickel-Titanium (Ni-Ti) instruments using a scanning electron microscope (SEM) for five successive uses in preparing root canals of extracted human molars and also to determine whether the design of the instrument influenced the appearance of defects on the instrument surface.
METHODS: Four different types of instruments namely; ProFile, ProTaper Rotary, ProTaper Hand and K3 Endo were used in 300 mesio-buccal canals. The instruments were examined under the SEM, after every use, to assess the progress of changes on their surfaces for a maximum of five uses.
METHODS: Chi-square test.
RESULTS: The most prevalent defects observed were pitting, followed by metal strips. Signs of discontinuity, microfractures and disruption of cutting edge were also evident. Number of defects increased with successive uses.
CONCLUSIONS: ProTaper Hand showed significantly more microfractures and metal strips than other instruments from third use onwards. ProTaper Rotary and K3 Endo also showed significant changes.