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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 7  |  Issue : 2  |  Page : 76-79

Visualization of enamel rods in hunter-schreger bands and enamel in incipient lesion under polarized and light microscopy


Department of Oral and Maxillofacial Pathology and Microbiology, D.Y. Patil University, School of Dentistry, Nerul, Navi Mumbai, Maharashtra, India

Date of Submission12-Dec-2019
Date of Decision08-Jan-2020
Date of Acceptance17-Mar-2020
Date of Web Publication09-Jun-2020

Correspondence Address:
Dr. Sandhya Tamgadge
Department of Oral and Maxillofacial Pathology and Microbiology, D.Y. Patil University, School of Dentistry, Sector 7, Nerul, Navi Mumbai - 400 706, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/sjos.SJOralSci_93_19

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  Abstract 


Background: An enamel rod is the basic unit of tooth enamel measuring 4 μm wide to 8 μm high and is tightly packed, highly organized mass of hydroxyapatite crystals, which are hexagonal in shape and provide rigidity to the rods and strengthen the enamel. In cross section, it is best compared to a keyhole with the top, or head, oriented toward the crown of the tooth and the bottom, or tail, oriented toward the root of the tooth. Enamel rods are found in rows along the tooth. The arrangement of crystals within each enamel rod is highly complex and gives rise to Hunter–Schreger Bands. This article presents enamel rods in Hunter–Schreger Bands under light microscopy and polarized microscopy which has rarely been reported with additional note on incipient lesion visualized under polarized microscopy.
Aim: 1. To visualize enamel rods in Hunter–Schreger Bands under light microscopy and polarized microscopy. 2. Visualization of Zones of enamel in incipient lesion under polarized microscopy.
Materials and Methods: Two ground sections were prepared. One normal (without lesion) and the other one was having incipient lesion (white spot). Normal tooth was visualized under light and polarized microscopy under x4,x10,x40,x100 under a light microscope, Leica research microscope (Leica application suite [LES]core version 3.8) of Leica research microscope (Model No. DM1000 LED, Leica Microsystems GmbH Ernst-Leitz-Stra e17–37 | 35,578 Wetzlar [Germany]) and tooth with incipient lesion was visualized under polarized microscopy.
Conclusion: Basic mechanism of Hunter Schreger bands can be studied at light microscopy. Zones of enamel in incipient lesion too, was clearly evident under polarized microscopy.

Keywords: Enamel rods, Hunter–Schreger bands, light microscopy, polarized microscopy


How to cite this article:
Tamgadge S, Pereira T, Tamgadge A. Visualization of enamel rods in hunter-schreger bands and enamel in incipient lesion under polarized and light microscopy. Saudi J Oral Sci 2020;7:76-9

How to cite this URL:
Tamgadge S, Pereira T, Tamgadge A. Visualization of enamel rods in hunter-schreger bands and enamel in incipient lesion under polarized and light microscopy. Saudi J Oral Sci [serial online] 2020 [cited 2020 Aug 8];7:76-9. Available from: http://www.saudijos.org/text.asp?2020/7/2/76/286219




  Introduction Top


Enamel is considered as the toughest tissue in the body and protects the crowns of the teeth to withstand heavy masticatory forces.[1],[2],[3]

Chemical composition of enamel comprised of inorganic and organic materials. Inorganic component of “prism” or “rod” shows specific interlocked arrangement of hydroxyapatite crystals which enhance the mechanical properties. In transverse section, each enamel rod composed of rounded head above and a tail below (look like keyholes or fish scales) forming a repetitive series of interlocking prisms. Rounded head of each prism (rod) lies between the narrow tail portions of two adjacent prisms. The tail portion is the organic component.[4],[5]

Each prism runs a wavy course from near the dentinoenamel junction (DEJ) to enamel surface and the paths undertaken by enamel prisms, including any decussations or bending, reflect the movements of the ameloblasts that form them during amelogenesis.[6]

It has previously been proved that under reflected light L.S of enamel shows an alternating series of dark and light bands.[7] These features are called as Hunter–Schreger Bands (HSBs)[8],[9] which is an optical phenomenon related to the changes in the path of enamel prisms as they travel from the DEJ to the enamel surface. It has also been suggested that the appearance of HSBs is related to the synchronous decussation of enamel prisms in the horizontal plane and is probably caused by reflection of light by interprismatic material.[10]

Enamel is made up of three structures: rods or prisms. rod sheaths, covering each enamel rod, and interrod substance. Each rod (prism) is filled with millions of hydroxyapatite crystallites and is formed by four ameloblasts. Enamel rod is surrounded by organic material known as rod sheath.[4]

Various authors have studied HSBs in a different teeth.[11],[12],[13],[14]

These rods undergo demineralization when attacked by caries-producing bacteria and show various zones histopathologically.[15]

Very few empirical data are available on enamel rods in health and caries under light microscopy and polarized microscopy. Therefore, the purpose of the study was to visualize enamel rods under light microscopy and polarized microscopy using higher magnification in normal and incipient lesion.


  Methods Top


This short study, technical note, was conducted at Department of Oral and Maxillofacial Pathology, D. Y Patil University, School of Dentistry, Nerul, Navi Mumbai. 100-μm thick ground section was prepared [14] and was mounted on a glass slide using Dibutyl Phthalate Xylene (DPX).

Sample selection

Noncarious tooth was selected to visualize enamel rods, and tooth with incipient lesion was selected to visualize zones of caries in enamel under polarized microscopy. Single sample for each technique was selected.

Ethical clearance was not needed as patients' identity was not revealed in the study.

The normal tooth specimen was examined under reflected light, transmitted light, and polarized light. The slides were then observed under Leica Research microscope Model No. DM1000 LED with Leica Image analysis software (Version. 3.8.0 (Model No.DM1000 LED, Leica Microsystems GmbH Ernst-Leitz-Straίe17–37 | 35,578 Wetzlar [Germany])) under × 4, ×10 and × 40 and x100 objective lens. Incipient lesion was observed under polarized microscopy.

Observations

  1. Histology of normal enamel rods in HSBs when observed in reflected light, transmitted light and polarized light – it showed alternate L.S. and T.S. of enamel rods [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
  2. Histopathology of incipient caries lesion showed various zones in enamel from advancing front to surface of enamel [Figure 6].
Figure 1: Histology of enamel under light microscopy showing alternate T.S (white arrow) and L.S (yellow arrow) of enamel rods (transmitted light (X40))

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Figure 2: Histology of enamel under light microscopy showing alternate L.S. and T.S. of enamel rods (reflected light (X40))

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Figure 3: Histology of enamel under polarized microscopy showing alternate L.S. and T.S. of enamel rods in ground section

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Figure 4: Histology of enamel under polarized microscopy showing alternate bands in ground section (×40)

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Figure 5: Histology of enamel under polarized microscopy showing alternate L.S. and T.S. of enamel rods in ground section (×100)

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Figure 6: Histopathology of incipient lesion of enamel under polarized microscopy showing various zones (×40)

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  Results Top


  1. NORMAL TOOTH–Transmitted, reflected light and polarized microscope clearly revealed basic mechanism of Hunter Schreger bands.
  2. INCIPENT LESION-Ground section revealed various zones of incipient caries of enamel under polarized microscopy.



  Discussion Top


Enamel rods have been studied extensively, using light and electron microscope. Electron microscope has been considered best technique to study individual enamel rod in health and disease [4],[15] but is considered very expensive techniques and technically difficult too.[16] Therefore, this article, a technical note, emphasizes on visualization of enamel rods under various magnifications using light and polarized microscope. Thus, this note highlight basic structure of HSBs which is easy to perform at every setup as compared to scanning electron microscopy and transmission electron microscopy and other expensive techniques. When enamel rods examined under bright field and polarized microscopy, it showed keyhole pattern and HSBs, showing rods running in alternate direction.

Similarly, when caries examined under polarized microscopy, it showed various zones in enamel as mentioned in literature.[16],[17]


  Conclusion Top


Histology of HSBs and carious enamel has been studied under light and polarized microscopy. New techniques should be developed in future to visualize thin sections of enamel under bright field in a better way.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Boyde A. Microstructure of Enamel. In: Chadwick D, Cardew G, editors. Dental Enamel (Ciba Foundation Symposium 205). Chichester: Wiley; 1997. p. 18-31.  Back to cited text no. 1
    
2.
Rensberger JM. Mechanical adaptation in enamel. In: Koenigswald WV, Sander PM, editors. Tooth Enamel Microstructure. Rotterdam: Balkema; 1997. p. 237-57.  Back to cited text no. 2
    
3.
Boyde A. The Structure and Development of Mammalian Enamel Ph.D. Thesis, University of London. London, UK; 1964.  Back to cited text no. 3
    
4.
Kumar GS. Orban's Oral Histology and Embryology. New Delhi: Elsevier; 2010. p. 52.  Back to cited text no. 4
    
5.
NANCI A, TEN CATE AR. In: Ten Cate's Oral Histology: Development, Structure, and Function. St. Louis, Mo: Mosby; 2003.  Back to cited text no. 5
    
6.
Osborn JW. Variations in structure and development ofenamel. In: Melchior AH, Zarb GA, editors. Oral Sciences Reviews 3: Dental Enamel. Copenhagen: Munksgaard; 1973. p. 3-83.  Back to cited text no. 6
    
7.
Hunter J. The Natural History of the Human Teeth: explaining Their Structure, Use, Formation, Growth, And disease Including a Practical Treatise on the Diseases of The teeth: Intended as a Supplement to the Natural History of these Parts. 2nd ed. J. Johnson, London: Facsimile Reproduction Published in 1980 by The Classics of Medicine Library; 1778.  Back to cited text no. 7
    
8.
Homma K. Historical studies on the striae of Hunter-Schreger. Dent Jpn (Tokyo) 1990;27:141-5.  Back to cited text no. 8
    
9.
Osborn JW. The nature of the Hunter-Schreger bands in enamel. Arch Oral Biol 1965;10:929-35.  Back to cited text no. 9
    
10.
Osborn JW. A 3-dimensional model to describe the relation between prism directions, parazones and diazones, and the Hunter-Schreger bands in human tooth enamel. Arch Oral Biol 1990;35:869-78.  Back to cited text no. 10
    
11.
Lynch CD, O'Sullivan VR, Dockery P, McGillycuddy CT, Sloan AJ. Hunter-Schreger band patterns in human tooth enamel. J Anat 2010;217:106-15.  Back to cited text no. 11
    
12.
Joshi PS, Bhosale SS. Study of enamel rod end patterns using acetate peel technique and automated biometrics for personal identification. Int J Dent Med Res 2014;1:47-50.  Back to cited text no. 12
    
13.
Manjunath K, Sivapathasundharam B. Analysis of enamel rod end pattern at different levels of enamel and its significance in ameloglyphics. J Forensic Res 2014;5:235.  Back to cited text no. 13
    
14.
Bancroft J, Gamble M. Histological Techniques, Theory and Practice. 5th ed. London: Churchill Livingstone; 2002.  Back to cited text no. 14
    
15.
Shafer WG, Hine MK, Levy BM. Dental Caries. In: Shafer's Textbook of oral pathology. 5th ed. Amsterdam: Elsevier; 2006.  Back to cited text no. 15
    
16.
Schüpbach P, Guggenheim B, Lutz F. Human root caries: histopathology of initial lesions in cementum and dentin. J Oral Pathol Med 1989;18:146-56.  Back to cited text no. 16
    
17.
Nishikawa T, Yoshida S, Tanaka A, Zoellner H, Walker DM. Histological Aspects of Human Enamel Fissure Caries studied by CLSM. MICROSCOPY AND ANALYSIS J Microscopy and Analysis (UK). 2003;93:23-5..  Back to cited text no. 17
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]



 

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