World Oral Health Day 2018 Celebrated at College of Dental Surgery BPKIHS, Say Ahh : Think Mouth, Think Health

World Oral Health Day 2018 was celebrated by multiple events like poster and flex competition, Speech competition and Table Clinic Competition. College of Dental Surgery, BPKIHS in coordination with Nepal Dental Association, Sunsari, organized the program. Also, 4th year BDS students as a part of their social responsibility for public awareness acted out a play regarding health hazards of drinking, smoking and chewing areca nut. The winners of Poster competition were Shabnam Gurung and Pratima Rai of BDS 2014 batch and the winner of Table Clinic Presentation were Anumesh Dahal and Nitika Santhaliya.





WATCH THIS VIDEO OF THE PROGRAM




























Unit 1 - Blood - Physiology Past Questions - MBBS / BDS First Year - BPKIHS

PHYSIOLOGY - UNIT 1 BLOOD

2017
1.  Describe briefly the kinetics and life span of leucocytes. Compare and contrast the functions of neutrophils and eosinophils. 2+3=5
2.  Describe the sequence of reactions to mismatched blood transfusion. 5
3.  Explain the genesis of granulocytes and their regulation using flow chart. 5
4.  Explain the anticoagulant mechanisms of endothelium of blood vessel. 5
5.  Describe the role of platelets in hemostasis. 5


2016
1.  Enlist the functions of plasma proteins. Explain any one of them. 2.5+2.5=5
2.  What is cross matching in blood transfusion? Explain its significance. 3+2=5
3.  Define hemostasis and describe about any 3 anti-clotting mechanisms in the body 2+3=5
4.  Explain the different stages of erythropoiesis with a diagram. 5
5.  Differentiate between intrinsic and extrinsic pathways of blood coagulation. 5

2015
1.  What is Rh factor? Explain the consequence of Rh incompatibility in blood transfusion and pregnancy. 1+5=6
2.  Describe the role of endothelium blood vessels in anticlotting mechanism. 4
3.  Describe the cytoskeletal proteins of RBC. List 4 advantages of biconcavity of RBC. 3+2=5
4.  Draw a flow-chart showing stages of erythropoiesis. State the role of erythropoietin on it.  3+2=5
5.  Enlist five functions of plasma proteins. Explain any one of them. 3+2=5

2014
1.  State any four factors regulating erythropoiesis. Explain the most important factor among them. 2+3=5
2.  Enlist any five functions of plasma proteins. Describe any one of them. 2.5+2.5=5
3.  What is cross matching in blood transfusion? Explain its significance. 3+2=5
4.  Explain the intrinsic pathway of blood coagulation with the help of a flow diagram. 5
5.   Explain the role of thrombomodulin and plasminogen in anti-clotting mechanism 2.5+2.5=5


2013
1.  Explain the mechanism of clot dissolution. 5
2.  Mention any four mechanisms that normally prevent coagulation of blood inside the blood  vessels. Describe any one them. 2+3=5
3.  Describe the regulatory role of erythropoietin in red blood cells production. 4
4.  State Landsteiner’s law of blood grouping with examples. 3+2=5
5.  Mention any four functions of plasma proteins. Describe
any two of them. 2+2+2=6


2012
1.  Describe various stages of erythropoiesis with changes that occur during each successive stage. 4+2=6
2.  Briefly describe the fate of hemoglobin breakdown. 5
3.  Describe briefly the mechanism of platelet plug formation. 4
4.  Explain in brief the anti-fibrinolytic mechanisms. 5
5.  Briefly describe Rh incompatibility. 5

2011
1.  Define cytokines. Explain their role in hemopoiesis with flowchart. 1+4=5
2.  Explain the role of endothelium of blood vessels inn anti- clotting mechanism. 5
3.  How circulatory neutrophils invade the offending agents in an area of tissue damage & perform the bactericidal effect? 3+2=5
4.  Describe the consequences of mismatched blood transfusion. 5
5.  Explain the role of erythropoietin in the erythropoiesis. 5

2010
1.   List the major contents of platelets and briefly function. 5
2.  Describe the regulation of erythropoiesis. 5
3.  Describe the erythroblastosis fetalis. 5
4.  Describe the anti-clotting mechanisms. 5
5.  Describe the leucopoiesis. 5






Mechanism of Bonding agents and Bond Strength on Cementum Surfaces compared to Dentin and Enamel

The American Society for Testing and Materials (specification D 907) defines adhesion as “the state in which two surfaces are held together by interfacial forces which may consist of valence forces or interlocking forces or both.” (ref. 2)

In dentistry, bonding of resin-based materials to tooth structure is a result of four possible mechanisms, as follows: (ref. 3)

  • Mechanical
  • Adsorption
  • Diffusion
  • Combination of above three



For good adhesion, close contact must exist between the adhesive and the substrate (enamel or dentin). The surface tension of the adhesive must be lower than the surface energy of the substrate.

ENAMEL
Acid-etching transforms the smooth enamel into an irregular surface and increases its surface free energy. When a fluid resin-based material is applied to the irregular etched surface, the resin penetrates into the surface, aided by capillary action. Monomers in the material polymerize, and the material becomes interlocked with the enamel surface. (ref 4,5) The formation of resin microtags within the enamel surface is the fundamental mechanism of resin-enamel adhesion. (ref. 6,7)
Scanning electron micrograph (SEM) of enamel etched with 35 % phosphoric acid for 15 seconds

DENTIN
Adhesive materials can interact with dentin in different ways—mechanically, chemically, or both. The importance of micromechanical bonding, similar to what occurs in enamel bonding, has become accepted. (ref. 8) Dentin adhesion relies primarily on the penetration of adhesive monomers into the network of collagen fibers left exposed by acid etching. (ref. 9,10) However, for adhesive materials that do not require etching, such as glass ionomer cements and some phosphate-based self-etch adhesives, chemical bonding between polycarboxylic or phosphate monomers and hydroxyapatite has been shown to be an important part of the bonding mechanism. (ref. 11)
Higher magnification view of dentin etched with 35 % phosphoric acid, col- collagen exposed by the acid, D- normal dentin,  T - dentinal tubule, S- residual silica particles used as acid gel thickener
CEMENTUM
Cementum is the first target for plaque bacteria attack in the process of root caries formation, and is still thought to be the most unpredictable area of an adhesive resin restoration. Cementum hybridization is related to structure, chemical composition and bonding efficacy of human cementum, which has a lower packing density than dentin. Cementum is a specialized and mineralized tissue (20–200 micrometers thick), pale yellow with dull surface. The principal inorganic component is hydroxyapatite while other forms of calcium are also present. It is considered to be rich in organic phase (about 50%) of collagen fibers and other matrix proteins. The ultrastructure of etched cementum surfaces was of a more spongy appearance with a large collagen fiber network compared with that of dentin, displaying longer and more deeply voluminous array of tufted fibrils. It is less hard and more permeable to a variety of materials compared with enamel and dentin.

Cementum in the cervical area is an acellular extrinsic fiber cementum. This substratum is a nonuniform, and relatively rough tissue. Human cementum can be represented as a woven fabric-like material that provides tissue porosity and permeability. One of the surface features that distinguish demineralized cementum from dentin is a lack of patent tubule orifices. With an absence of these openings, cementum is at a distinct disadvantage when it comes to enhanced bonding adhesion.
AFM (Atomic force microscopy) images of 50 micrometer * 50  micrometer area of 35% H3PO4 etched cementum




References:
1. Sturdevant's Art and Science of Operative Dentistry, 6th Edition
2. Packham DE: Adhesion. In Packham DE, editor: Handbook of adhesion, Essex, UK, 1992, Longman Scientific & Technical, pp 18–20.
3. Söderholm K-JM: Correlation of in vivo and in vitro performance of adhesive restorative materials: A report of the ASC MD156 Task Group on test methods for the adhesion of restorative materials. Dent Mater 7:74–83, 1991.
4. Asmussen E, Munksgaard EC: Bonding of restorative materials to dentine: Status of dentine adhesives and impact on cavity design and filling techniques. Int Dent J 38:97–104, 1988.
5. Buonocore MG, Matsui A, Gwinnett AJ, et al: Penetration of resin into enamel surfaces with reference to bonding. Arch Oral Biol 13:61–70, 1968.
6. Barkmeier WW, Shaffer SE, Gwinnett AJ, et al: Effects of 15 vs 60 second enamel acid conditioning on adhesion and morphology. Oper Dent 11:111–116, 1986.
7. Gwinnett AJ, Matsui A: A study of enamel adhesives: The physical relationship between enamel and adhesive. Arch Oral Biol 12:1615–1620, 1967.
8. Erickson RL: Surface interactions of dentin adhesive materials, Oper Dent 5(Suppl):81–94, 1992.
9. Van Meerbeek B, Ionkoshi S, Braem M, et al: Morphological aspects of the resin-dentin interdiffusion zone with different dentin adhesive systems. J Dent Res 71:1530–1540, 1992.
10. Tay FR, Gwinnett AJ, Wei SH, et al: Ultrastructure of the resin-dentin interface following reversible and irreversible rewetting. Am J Dent 10:77–82, 1997.
11. M. Toledano, E. Osorio, F.S. Aguilera, G. Gomes, J. Perdigão, R. Osorio, Bond strength and nanoroughness assessment on human pretreated cementum surfaces, Journal of Dentistry, Volume 38, Issue 8, 2010, Pages 678-685, ISSN 0300-5712, https://doi.org/10.1016/j.jdent.2010.05.011. (http://www.sciencedirect.com/science/article/pii/S030057121000120X) Keywords: Adhesion; Dental; Cementum; Phosphoric acid; Etching; Self-etching; Adhesives; Nanoroughness; Surface; AFM


MCQs on Radiographic Diagnosis - Oral Medicine and Radiology


# All of the following are radiolucent except:
A. Ameloblastoma
B. Cementoblastoma
C. Keratocyst
D. Central giant cell granuloma

# All of the following will appear like caries in an X ray EXCEPT:
A. Acrylic resin
B. Calcium hydroxide
C. ZOE
D. Composite