TEACHING HUNT CONTESTANT NO 17 ENAMEL Dr. GAGAN AGRAWAL

good evening everyone i am gagan agrawal from sharadpur dental college today the title of my presentation is something new something exciting any guesses so by looking at this picture what all you think the picture is showing something like brittleness translucent structure heart structure any guesses what is it so let's have a look once so this structure is about enamel every one of us know what is enamel enamel is nothing but a hard translucent tissue covering the anatomical crowns of the teeth of man and most of the mammals enamel is also called sustaintica or aminoblast amino from where abnormal is product developed from enamel is developed from gene that names is ctpi2 that controls to the normal production this is transcription factor which regulates skin and nervous system discovered by krisakuci a krisakuci he is from arghan state university so what enamel composed of it's a structure now that something is in direct supports that it consists of inorganic matter 96 percent organic matter one percent and water three percent among organic matter includes tyrosine rich and melatonins and non-aminogenic inorganic matter includes calcium phosphate hydroxyapatite crystals fluoride strontium magnesium and lead and apart from this it consists of three percent of water now what are the physical properties the physical properties of enamel includes extremely hard like mild steel so it can withstand mechanical forces as you all see in this picture uh this enamel is very extremely hard like mild steel why it can waste mechanical forces during mastication it's my uh mastic etc but maximum bulk around 2 to 25 mm at crystal region and knife edge thickness at neck region as you're seeing this saw in the speaker specific gravity of enamel is 2.8 permeability it acts as a semi permeable membrane for c-level urea eye etc color light yellow to grayish white depends upon translucency of enamel that is attributable to glass calcification and homogeneity now normal structure what are the normal structures what are the structures that is related to first enormous structure consists of enamel prisms enamel rods prism sheets also known as rod strength interprismatic substance that is also known as inter or cementing substances first enamel rods enamel rods are long slender structures with roughly five or six sides extending from the interior normal junction to the structure in very coarse and oblique direction the length of the rods are greater than the thickness of the enamel the diameter of the rods average 4 micrometer along the internal normal junction and becomes doubt at the surface becomes double at the surface of it the enamel rods normally have a clear crystalline appearance permitting light to pass through them they appear hexagonal round or oval and many resemble fish scales so in this you are looking at enamel rods these are baby in courses yeah obliquely direction publicly detected seconds ah oh in permanent teeth the direction of normal rods are similar to that of the decedent street at occlusion two third but at the cervical region the root directed root wise so the enamel length cervically as a knife h second is prism sheet prism sheet is the outermost portion of the rod and takes strains easily because it has more organic substance it is a substance which cements the rods together it is approximately 1 micron thick and believed to have proliferated from terminal bar apparatus as enamel globules are developed this is about inter prismatic substance some microscopic structure of enamel the rods in cross sections has a common pattern keyhole or paddle shaped pattern with head and tail in longitudinal section the heads or bodies in between the tails of adjacent rods will appear like rods are separated by interprismatic substance so when we use when we wave some microbic structure of enamel a keyhole or paddle shaped pattern is gift as you see in this figure the appetite crystals appear flat ribbon-like and arranged with their long axis paralleling the long axis of rods some crystals may diverge as much as 40 to 60 degree from the axial plane of the rods if someone asks you what are the appetite crystals what are what is the arrangement of a patented crystal sense of microbic structure so the pythagorean crystals arrangement is like flat ribbon like and with their long axis paralleling the long half of the rods some crystals may diverge as much as 40 degree to 65 degree from the axial plane of the rods like in this figure now structural characteristics what are the structural characteristics of enamel so transverse transitions hunter's trigger bands incremental lines of resist enamel lamella enamel tufts enamel spindles enamel cuticle and pellicle these all constitute its structural characteristics of enamel so first we will see one by one what is first is transverse striations lines across the rods with four microns internal which becomes more visible when in contact with acid it marks the daily depositional growth of the veinaman rods more prominent cross tractions occur in a regular period of about every four days for one week and are known as a stray of red zeals or incremental lines transfer stations are also known as incremental line of arrest yes see when you give microscopic structure these are the transverse striations also known as triophralzias or incremental line of right cs second is hunter sugar bands what are hunter sugar bands under sugar bands are alternating light and dark bands originating from the entire normal junction towards the surface these are originating from dej towards the surface these are caused by different directions of rods or crease crossing of rods so that in longitudinal section some rods are cut transversely diazone or dark zone and some are cut longitudinally parazone or light zone so the rods which are cut longitudinally are known as parazon or light zone and the rods which are cut transversely they are known as diazona dark zone like in this figure c how hundred sugar brands are developed or hunter sugar brands is seen in microscopic structure incremental line of regions brand these are the brownish lines that mark the growth periods of enamel beginning and ending layers of enamel it represents every primary calcification in the analysis pericarmita and united line or brain it represents every primary calcification in the enamel focus on this statement pericarmata or it is all neonatal line or ring stray of red cs see in this figure what are peri kamatas periga might have nothing but indication lines of pickering transfer wave like grooves that are thought to be the external manifestations of strife itself perigamet are nothing but the external manifestations of star of redzirs see in this figure the both lines of rexius and pericum hat is depicted see now in first figure healthy tooth with intact pericarmata now in second figure partial loss of origami is there what is neonatal line neonatal line is something like ring so neonatal line are defined as accentuated lines of resist differentiating the parent prenatally developed enamel from postnatal enamel nutella and nylon is that line which differentiate prenatally developed enamel from post natal enamel present in all decedent and first permanent molar this is very important neonatal line is present in all deciduous state and in permanently it is present only in first permanent mula this is believed to be the result of abrupt change in the environment and nutrition of the newborn infant this is in this figure prenatal line neonatal line and postnatal line so what is neonatal line you see as you see in this figure it differentiates prenatal enamel from the post metal enhancer what are enamel lamella in our lamellar nothing but leaf-like structure defects extending from the surface of the normal towards the interior so enamel lamellar nothing but a surface structure extending from enamel towards the interior enamel there are three types of enamel lamella type a type b and type c so type a is true lamellar it is hypocalcified prisms an inter prismatic substance it is limited to enamel only what is type a hypercalcified prisms and inter prismatic substance now coming to type b what are enamel lamellae type b enamel cracks pre-eruptive can reach dentine filled with epithelial cell or connective tissue so type b somewhat risk to the dentin it is somewhat rich to dentine and type c these are enamel cracks post adaptive can rich dainty filled with organics or content of saliva so in short type a is limited to enamel type b somewhat goes to the optin tin and type c totally goes into dentine enamel terms enamel taps are narrow ribbon-like structure composed of bundles of poorly calcified rods and inter-rod cementing substance originating from dentinal junction the term tuft is used because the structure is resembles the blades of grass attached to the parent stream so when you look is microscopic structure you see normal dogs it is look like grass like structure as you see in this figure what are enamel spindles club shapes extensions or projections of the internal tubules into the enamel it is an aromatoplasty process which extends between the cells of inner gentle epithelium before the formation of enamel this is one of the factor that causes the hypersensitivity of intuitive normal junction so enamel spindles are one of the factor that causes hypersensitivity of the internal normal junction siege this is enamel sprinkles now enamel cuticle and pelican what is an amal cuticle nasmus membrane is a delicate membrane that covers the crown of newly erupted tooth but is probably soon removed by mastication nasmith emblem is nothing but is much so much delicate membrane that covers the crown of newly erupted tooth but is probably soon removed by mastication pelican are precipitations of the salivary proteins covering the erupted enamel and may be colonized later by bacteria and food debris see in this figure in animal cuticle see play constraints uh now second is second layer you see helical appear as a homogeneous layer between plaque and tooth enamel when plaque on steroids attacks your teeth they don't attach to the enamel instead they attach to the protein particle layer when plaque and strains attack the vein plaque and still supply your teeth they do not touch the enamel they touch to the protein like pelican layer scalloped into the normal junction the dentine surface on the crown has shallow depressions or pits where the normal caps are fitted resulting to the irregular or scalloped appearance of the junction of enamel and dentine this provides a form attachment of enamel to the grinding surface so what is the purpose of the interior normal junction the internal normal junctions purpose is it provides form attachment of enamel to the dentin surface see scalloped pattern the ej internal junction now we talk about enamel structures in normal characteristic physical properties of enamel and all and all but varies from enamel develop now we will see enamel development enamel organ originating from the stratified epithelium of the stomodium consists of four distinct layer stromodium is the mouth oral cavity beginning of the beginning oral cavity stomach it consumes four distinct layer when it develops it consists of four distinct layers that are outer enamel epithelium stila reticulum stratum intermediate and inner normal epithelium authoring epithelium outer bottle cells of a normal organ which becomes irregularly producing loops where capillaries are found serve as a protective barrier for enamel organ during enamel formation cells develop vesicles and villi and a large number of mitochondria indicating that active participation of cells in the transmission of nutrition outer enamel epithelium helps in the participation in transmission of nutrition to the cells still at reticulum still at reticular nothing these are star shape cells in many layers forming a network within the normal organ it supports the production of enamel matrix it is resistant and inelastic therefore it act as buffer against physical forces that might distort the confirmation of the developing ddj it becomes reduced in size thus it shortens the path of nutrition that comes from the outside as enamel gets his nutrition from after enamel epithelium but now this chili particular rod does what it reduces in size and then shortens the path of nutrition that comes from the outside stratum intermediate in the next layer more inner compressed compressed layer of flat tube bottle cells also supports the production of cinnamon matrix the cells show mitotic division even after the cells of the inner enamel epithelium cease to divide inner enamel epithelium innermost alcohol of the cell having an organ it will differentiate into ameloblast to that form in another matrix the inner enamel epithelium is that layer which will differentiate into amino glass what are ameloblasts amino blaster enamel forming cells that form enamel matrix cervical loop when the crown has been formed the cells of this portion give rise to heart fix the epithelial root sheet cervical loop is nothing but suffering the crown has formed the cells of this portion of i also call that the position of normal matrix it is a process of development of enamel consisting of two phases so amelogenesis is consistent constitute of two phases one is formative phase and other is mineralization and maturation phase formative phase is also known as matte organic matrix formation and mineralization and maturation phases and second phase formative phase where there is a formation of enamel matrix formation of the entire normal high membrane the ameloblast deposits a thin matrix extracellularly on the surface of the dentine uniting with the membrane for performativa to become the dengue normal junction so this is formative phase formation of tom's process now in the top formative phase there is a formation of tom's versus how the protoplasmic projections of ameloblast into the matrix are the terms processes that appear as rows of projections extending intracellularly responsible for the way the normal matrix is laid down isolation of terms process from the cell body of enamel of amiloblast by condensation of cytoplasmic substance closely associated with secant cell membrane called terminal bar also known as distal terminal bar in of the distal enough terms process with matrix material from the meloblast formation of the fully formed segments of rods are the pre-enamel rods see in this figure tom's process raw sheet inter or normal enamel rods now second is mineralization and maturative phase the first stage of an intermediate partial immunization occurs in the matrix segment and anti-prismatic substance as they are laid down the first mineral is actually in the form of crystalline apatite so enamel is nothing but first mineral is actually in the pathetic in the form of apatite crystal the second stage of maturation starts the height of the crown and progresses cervically second stage starts from height of the ground to progress and it progresses cervically seems to begin at a dentinal end of the rod it begins before the matrix has reached its full thickness in normal penetration in our maturation is occurs from cut step or inside the lid and progress cervically the maturation of the crystal begins adjusting diode internally and progresses to the outer surface at first parallel to internal normal junction and later to the outer surface of enamel maturation occurs by growth of the primary crystals till they fuse together the fibrils between the crystals will become thinner after eruption the maturation continues by deposition of ions from saliva to reach 96 of its weight in organic substance now what other what is life cycle of amiloblast this is the most important question of all examiners yeah because i am also an examiner i am also a student so i know this comes as i like you in my the edius question paper in first year currently i am in third year but this is most important and is always oxygen exam all the ways life cycle of homeoblast life cycle of amyloplasts includes six stages what are six stages morphogenic stage organizing stage formative stage maturative stage protective stretch and desmolitic stage the short form is morph mpd mof mpd of mpd yeah first morphogenic stage before the ameloblasts are fully differentiated and produced enamel they interact with adjacent resin caramel cells determining the shape of the dj and the crown during this stage the cells are short and columnar with large nuclei that almost fill the cell body in morphogenic stage nothing where the outer outer is outer outer portion is zero yeah organizing stage the ameloblast interacts with the cells of the dental papilla at the periphery which latter differentiates into odentoblast then cells become longer and nucleus freezones at the distal ends of the cells become almost as long as the proximal parts containing the nuclei after the first layer of dentin has been formed the presence of dentine seems to be necessary for the beginning of enamel matrix formation now informative state there are changes in organization and number of cytoplasmic organisms and inclusions are related to the initiation of the enamel matrix maturative stage enamel maturation occurs after most of the thickness of the normal matrix has been formed in the occlusal or incisal area amyloblasts display microvilli at their distal extremities and cytoplasmic vacuoles this structure indicates an absorptive function of this cells protective stage when the enamel has completely developed and has fully calcified the miloblast is to be arranged in a well-defined layer and can no longer be differentiate from the cells of the stratum intermedium and outer enamel epithelium this cell layer then forms stratified epithelial covering of enamel called reduced enamel epithelium that protects the enamel by separating it from connective tissue until the tooth erupts so reduced enamel epithelium protects the enamel by separating it from the connective tissue until the tooth heat ups reducing analysis is very important it is acts in bhava dysmolytic stage is the last stage the reduced normal epithelium that is formed in previous stage that is proliferative stage it seems to induce atrophy of the connective tissue separating it from the oral epithelium so that fusion of the two epithelia can occur it is probable that the epithelial cells elaborate enzymes that are able to destroy connective tissue fibers like desmosis now what are the clinical considerations now these are the normal of enamel yeah we will see what we are seeing now enamel characteristics enamel structures physical properties of enamel how the enamel develops the amino genesis life cycle of angular glass that includes six stages now we will see clinical conjugations but in what diseases enamel will suffer so first question is how does the knowledge of enamel affect cavity preparation while looking by looking at this figure the answer of that question is direct acid reaching enamel and bonding properties restorations and ceilings i'll be doing restorations on cylindrical or while doing gravity preparation it affects enamel effect the gravity depletion direct removal of unsupported enamel rods that is the normal pressure will be unsupported what makes enamel structure susceptible to carries crystals dissolved at low ph acid produced by karyogenic bacteria make enamel structure susceptible to carries enamel surface is porous and imperfect fits fissures and lamella how are carries and dental erosion similar or different same both involve chemical insult different k is due to bacterial action erosion due to environmental factors at what ph does enamel undergo dissolution what common dietary substance have a low ph answer is ph is range of 5 to 5.5 and what are what are the common dietary substances that have low ps the answer is soda props spots drinks citrus pickles etc the average american drinks more than 53 gallon of carbonated soft drinks each year more than any other beverage including milk beer coffee or water pop is a poor dietary choice for three reasons what accounts for the natural coloration of it what accounts for white spots enamel translucent and porous dnd shows through contrast with facial or hair color impaired translucence of enamel creates optical white spots what are some environmental factors that affect enamel formation how do this occurs nutrition systemic diseases systemic diseases like diabetes mellitus hypertension thyroidism high fever tetracycline trauma fluoride etc this occurs during tube development tip development includes four stages burst stage cap stage early bill switch and advanced barrel stage in advanced bill stage the development of enamel takes place how does fluoride affect enamel there are two mechanism protective function and by too much affects fluorosis protective function indicates inhibitor of crystal dissolution and remineralization with fluoroapatite crystals what are some mercury conditions affecting enamel the identity conditions that affecting enamel are amelogenesis imperfecta ectodermal dysplasias excitra ectodermal dysplasia is a disease of skin it is a disease of skin amelogenesis imperfect term is a condition where there is a disturbance in the formation and maturation of enamel matrix enamel hypoplasia result of the disturbance in matrix formation clinically the surface of enamel may develop its fishes or grooves or enamel may be very thin in animal hypo calcification results of disturb mineralization of enamel matrix clinically the enamel appears rocky white or opaque and soft in a half enamel hypercalcification enamel appear as chalky white or opaque and soft so thank you you don't have to brush all your teeth just the ones you want to