Dentinsko-gleni spoj (DGS)Neravan spoj ojaava vezu i poveava kontaktnu povrinu izmeu glei i dentina

Specifini proteini u DGS imaju ulogu cementa

Tomesova vlakna uzidana u glenu supstancu

Glena vretenaA-glena vretenaB-dentinski tubuli

Glena vretenaA-glena vretenaB-dentinski tubuliC-glene prizme Pruaju se od DGS-a prema povrini glei, ali ne prate pravac pruanja glenih prizmi

Glena vretena

Gleni strukovi (bunovi)Reflektuju delove glei sa veim sadrajem proteina, posebno tuftelina

Pruaju se od DGS-a i zahvataju 1/10 do 1/3 debljine glei

Imaju regularan, periodian raspored, to ukazuje na mogui znaaj u vezivanju glei za dentin

Imaju veu duinu i irinu od glenih vretena

Glena vretena i strukoviGlena vretenaGleno-dentinskispojGleni strukoviGleno-dentinskispoj

Gleni strukoviGlena vretena

Glene lamele i pukotineInkrementne linijeGlenavretenaGlenalamelaGlenistruk

Glene lameleNastaju kao posledica lokalnih poremeaja u maturaciji gleiSadre veu koliinu vode i organskih materijaOdlikuju se veim stepenom permeabilnosti od okolne glei

Glena vretena, strukovi i lamele

Gleni strukovi i lameleA-gleni strukoviB-glena lamela

Glene lamele i strukovidentindentingle

Permeabilnost gleiGle je relativno nepropusno tkivo, ali voda i minerali u odreenoj meri mogu difundovati kroz njega

Najpropustljiviji delovi glei su glene lamele i pukotine

Permeabilnost gleiMikrolamelePukotina u glei

Glena kutikulaMembrana koja pokriva gle u toku erupcije zuba

Primarna kutikula membrana debljine 50-150 nm koju lue ameloblasti; ona je slinog sastava kao bazalna lamina i vrsto prijanja za povrinu glei

Sekundarna kutikula (Nasmythova membrana) omota od redukovanog glenog epitela koji otpada odmah posle erupcije zuba

Salivarna pelikla organski depozit koji se stvara na povrini krunice nekoliko minuta posle uklanjanja pranjem zuba; predstavlja pogodnu podlogu za taloenje dentalnog plaka

Glena pelikla Salivarna pelikla organski depozit koji se stvara na povrini krunice nekoliko minuta posle pranja zuba

Debljina 0,5-1 m

Ima protektivnu ulogu u odnosu na gle, ali predstavlja pogodno tlo za razvoj dentalnog plakaGleGDSDentinPelikla

Odravanje gleiSupstance iz pljuvake su od esencijalnog znaaja za odravanje glei

U gle prodiru:digestivni enzimiantibakterijski enzimiantitelaminerali

KarijesDekalcifikacija glei deava se pod uticajem kiselina koje produkuju bakterije

Uzrasne promene gleiAtricijaeliminacija glei usled dejstva mastikatornih silaAbrazija uklanjanje glei pod uticajem mehanikih sila (etkice za zube, abrazivne paste, proteze ...)Erozijaabrazija u predelu vrata zubaDiskoloritetdeponovanje pigmentnih supstanci?istanjenje glei?Snien permeabilitet

Najpermeabilniji delovi glei su:a) glena vretenab) glene prizmec) Retziusove strijed) glene lamele

Kako se zovu hipomineralizovani delovi glei koji sadre Tomesove produetke?

Glena vretena

Enamel - transverse ground section In a transverse section of tooth, the stria of Retzius appear as concentric bands parallel to the dentino-enamel junction (DEJ). In addition to the "hypo-mineralized" dark stria of Retzius, there also exist hypo-mineralized areas perpendicular to the DEJ. These are enamel lamellae (that traverse the entire thickness of enamel) and enamel tufts (that traverse the inner third of enamel adjacent to the DEJ. Previous SlideBack to Chapter 2 IndexNext SlideLegend: A, Stria of Retzius; B, Enamel tuft; C, Enamel lamella; D, Dentino-enamel junction

Neonatal line The neonatal line is a dark stria of Retzius that occurs at the time of birth. It is due to the stress of birth. The neonatal line is usually the darkest and thickest stria of Retzius. The enamel at the cusp of the tooth generally exhibits a wavy pattern. This enamel is called gnarled enamel. This is NOT hypo-mineralized. The enamel rods are layed down in this pattern by ameloblasts to make the enamel strong in this region. Previous SlideBack to Chapter 2 IndexNext SlideLegend: A, Gnarled enamel; B, Neonatal line; C, Dentin; D, Dentino-enamel junction

Straight enamel rods - longitudinal labiolingual section The enamel rods project in the direction of the arrow. Can you see the stria of Retzius?

Gnarled enamel Enamel rods are general not straight throughout their length. In the cuspal region, the rods are very wavy. This is referred to as gnarled enamel. In this section, you can see the end of an odontoblastic process penetrating the enamel just past the DEJ. This structure is called an enamel spindle.Previous SlideBack to Chapter 2 IndexNext SlideLegend: A, Gnarled enamel; B, Enamel spindle

Cross-striations Each enamel rod demonstates closely positioned striations along its length known as cross-striations or incremental lines. These are thought to be formed by the daily rhythm of the ameloblast laying down more and less mineralized enamel. The striations are approximately 5 m apart. This distance represents one day of enamel deposition. In this micrograph rods project in the direction of the arrow. Can you see the striations on each rod? They are oriented perpendicular to the length of the rod. Note: Not the large dark bands projecting diagonally; these are stria of Retzius.Previous SlideBack to Chapter 2 IndexNext Slide

Enamel cut In enamel cut in perfect cross-section the shape of the enamel rod exhibits a "keyhole"-shaped pattern. However, in a normal cross-section of enamel, as seen here, most rods are cut obliquely. This is because they do not travel in a straight line. The micrograph on the left is produced by differential interference microscopy while the micrograph on the right is from transmitted light microscopy.

Enamel rods sectioned longitudinally In this electron micrograph enamel rods are cut longitudinally (in parallel with their long axis). The ligher band represents the inner part of the rod or rod core, while the darker part represents the outer covering or rod sheath. This difference in appearance is caused by the packing density of the rod hydroxyapatite crystals. In the core the crystals are packed in parallel with one another and tightly together (very mineralized), whereas in the rod sheath, the crystals are lossly packed and are oriented at variable angles to one another with organic material interspersed (less mineralized). In this particular section, the cores are narrow and the sheaths wide, signifying that this area is taken from a dark cross-striation or stria of Retzius. Note that the rod sheaths are shared by two adjacent rods.

Enamel rods sectioned in cross-sectionIn this electron micrograph enamel rods are cut perpendicular to their long axis. The ligher areas are the rod cores in which hydroxyapatite crystals are tightly packed in alignment with each other. The darker areas surrounding the rod cores are the rod sheaths in which the crystals are loosely packed at various angles. There are two main parts to a rod: the rod head and rod tail. The head has the central core (light area), and is sometimes referred to as the "rod". The tail is made of the rod sheath (less mineralized enamel). During development, one ameloblast (in position 1 in the inset diagram) makes the rod core for the rod at position 1, while three other ameloblasts (in positions 2, 3 and 4) produce the rod tail of rod 1. The tail is located between 2 and 3 and above 4. Previous SlideBack to Chapter 2 Index

Box diagram of human enamel This diagram represents a 25 X 25 X 25 m of enamel. It demonstrates the arrangements of hydroxyapatite crystals in the enamel rods in three planes of section. One rod is highlighted in blue to demonstrate the typical human rod shape. In the rod core, hydroxyapatite crystals are aligned with the long axis of the rod. In the tail the crystals are aligned diagonally or perpendicularly to the long axis of the rod. Previous SlideBack to Chapter

Alternating rod directionality Hunter Schreger bands are alternating light and dark bands seen in a section of enamel when cut longitudinally and illuminated in a special way. The bands are produced by the orientation of groups of rods. If the light passes through rods cut in cross-section, the band appears light. If the light passes through rods cut in longitudinally, the band appears dark. Previous SlideBack to Chapter 2 Index

Hunter-Schreger bands Hunter Schreger bands are seen here with special illumination in longitudinal ground sections of enamel as light and dark bands. The red arrows indicate three light bands.Previous SlideBack to Chapter 2

Enamel tufts Enamel tufts are less mineralized areas of enamel in the inner third of enamel adjacent to the DEJ. They resemble tufts of grass. They are wavy due to the waviness of the adjacent rods. Structures rich in organic matter (i.e. less mineralized) that project to the surface of the enamel are enamel lamellae. Previous SlideBack to Chapter 2 Index

Enamel tufts - two planes of focus Enamel tufts consist of several unconnected "leaves" of hypo-calcified enamel. They display a wavy twisted appearance. Enamel spindles are the processes of odontoblasts projecting into the enamel.Previous SlideBack to Chapter 2 Index

Enamel tufts aligned in rows Enamel tufts are aligned in rows. They may represent planes of tension during development. Previous SlideBack to Chapter 2 IndexNext Slide

Enamel lamellae In this ground cross-section of tooth, you can see enamel lamellae and enamel tufts You can also see the neonatal line. What do all three of these structures have in common?Previous SlideBack to Chapter 2 Index

Decalcified tooth In a decalcified section of tooth, only the organic material is left behind. In this micrograph you can see an enamel lamella and enamel tufts. Previous SlideBack to Chapter 2 Index

Odontoblast process Odontoblast processes usually end at the DEJ. However, sometimes the ends of the process become embedded in the enamel as it forms. These very small, usually straight structures that you can see adjacent to the DEJ are enamel spindles. They are only about one tenth the length of an enamel tuft. Previous SlideBack to Chapter 2 IndexNext SlideLegend: A, Enamel spindle; B, Odontoblast processes in

Enamel spindles In this high magnification of the DEJ you can clearly see the bifurcation of the ends of some of the odontoblast processes as well as enamel spindles. Previous SlideBack to Chapter 2 IndexLegend: A, Enamel spindle; B, Odontoblast process; C, Enamel rod

dentin