Mechanisms of vitamin A metabolism and deficiency in the mammalian and fly visual system.

Vitamin A deficiency can cause human pathologies that range from blindness to embryonic malformations. This diversity is due to the lack of two major vitamin A metabolites with very different functions: the chromophore 11-cis-retinal (vitamin A aldehyde) is a critical component of the visual pigment that mediates phototransduction, while the signaling molecule all-trans-retinoic acid regulates the development of various tissues and is required for the function of the immune system. Since animals cannot synthesize vitamin A de novo, they must obtain it either as preformed vitamin A from animal products or as carotenoid precursors from plant sources. Due to its essential role in the visual system, acute vitamin A deprivation impairs photoreceptor function and causes night blindness (poor vision under dim light conditions), while chronic deprivation results in retinal dystrophies and photoreceptor cell death. Chronic vitamin A deficiency is the leading cause of preventable childhood blindness according to the World Health Organization. Due to the requirement of vitamin A for retinoic acid signaling in development and in the immune system, vitamin A deficiency also causes increased mortality in children and pregnant women in developing countries. Drosophila melanogaster is an excellent model to study the effects of vitamin A deprivation on the eye because vitamin A is not essential for Drosophila development and chronic deficiency does not cause lethality. Moreover, genetic screens in Drosophila have identified evolutionarily conserved factors that mediate the production of vitamin A and its cellular uptake. Here, we review our current knowledge about the role of vitamin A in the visual system of mammals and Drosophila melanogaster. We compare the molecular mechanisms that mediate the uptake of dietary vitamin A precursors and the metabolism of vitamin A, as well as the consequences of vitamin A deficiency for the structure and function of the eye.

A comparative evaluation of the efficacy of erbium: yttrium-aluminum-garnet and diode lasers in smear layer removal and dentin permeability of root canal after biomechanical preparation - A scanning electron microscopy study.

INTRODUCTION: The chemomechanical preparation of root canal dentin with hand or rotary instruments creates debris and a smear layer. Root canal preparation (RCP) along with irrigants is not effective in cleaning apical portions, and hence, different laser activation systems were used for better cleaning in the apical third. Aim: The aim of this study is to compare the efficacy of erbium: yttrium-aluminum-garnet (Er:YAG) and diode laser irradiation in smear layer removal and dentin permeability after biomechanical preparation using scanning electron microscopic investigation. Material and Methods: Thirty sound single-rooted human teeth were distributed randomly and equally into three groups (n = 10 each) based upon the type of laser irradiation after RCP: Group I (control group) - RCP with ProTaper rotary system using the standard irrigating protocol; Group II - RCP with ProTaper rotary system using the standard irrigating protocol followed by diode laser irradiation; and Group III - RCP with ProTaper rotary system using the standard irrigating protocol followed by Er:YAG laser irradiation. After root sectioning, specimens were dehydrated, then gold plated and observed using a scanning electron microscopy. Then, the smear layer scores were recorded and performed using the statistical analysis. Results: Smear layer removal efficacy of Er:YAG laser was more at coronal, middle, and apical third when compared to Group I and Group II. Debris removal score of Group III (Er:YAG) was better than Group I (17% ethylenediaminetetraacetic acid) and Group II (diode). Conclusion: Er:YAG laser-activated RCP was comparatively efficient in cleaning the smear layer and dentinal tubules opening.

Clinical and Practical Implications of Storage Media used for Tooth Avulsion.

Replantation is being widely accepted as an effective treatment option for an avulsed tooth. However, the long-term fate of replanted teeth is unpredictable; it is dependent on various factors, such as the time interval between avulsion and replantation, extra-alveolar storage period (dry storage or storage media), the vitality status of pulp or periodontal tissues and the type and period of splinting. The appropriate use of storage media is an important clinical factor affecting the postoperative prognosis of avulsed teeth following replantation. Hank's balanced salt solution and pasteurized milk are considered to be the most appropriate and clinically recommended storage media for avulsed teeth. The present review discusses the various available storage media for avulsed teeth and their potential maintenance of the vitality of periodontal ligament cells. A brief overview of the effect of clinical factors, such as the storage time, pH, and the osmolar-ity of storage media on their efficacy is included. HOW TO CITE THIS ARTICLE: Khinda VIS, Kaur G, Brar GS, Kallar S, Khurana H. Clinical and Practical Implications of Storage Media used for Tooth Avulsion. Int J Clin Pediatr Dent 2017; 10(2): 158-165.

Management of pigmented gingiva in child patient: a new era to the pediatric dentistry.

Gingival health in the form of size, shape, consistency and appearance are essential components responsible for an attractive smile as well as may cause unpleasant appearance. Melanin pigmentation often occurs in the gingiva as a result of an abnormal deposition of melanin which can compromise the confidence level from the age of childhood. The present article describes and discusses the two cases of gingival melanin pigmentation in 12 and 13 years of female patient and their early surgical intervention with successful follow-up of 9 and 6 months. Patients were instructed to prevent sun exposure, intake of hot foods or beverages like cold drinks, tea, coffee and brushing immediately after surgery. How to cite this article: Bahadure RN, Singh P, Jain E, Khurana H, Badole G. Management of Pigmented Gingiva in Child Patient: A New Era to the Pediatric Dentistry. Int J Clin Pediatr Dent 2013;6(3):197-200.