Histopathology of Enamel Caries GN PDF

Histopathology of Enamel and Den4ne Caries Oral and Dental Science Josh Hudson GDC Learning Outcomes: 1.1.2 Describe oral diseases and their relevance to preven5on, diagnosis and treatment 1.1.4 Explain the ae5ology and pathogenesis of oral disease 1.1.6 Describe relevant and appropriate dental,...

Histopathology of Enamel and Den4ne Caries Oral and Dental Science Josh Hudson GDC Learning Outcomes: 1.1.2 Describe oral diseases and their relevance to preven5on, diagnosis and treatment 1.1.4 Explain the ae5ology and pathogenesis of oral disease 1.1.6 Describe relevant and appropriate dental, oral, craniofacial and general anatomy and explain their applica5on to pa5ent management Pre-reading ‘Ae5ology of Dental Caries’ Suscep4ble tooth surface Caries Lecture Time Plaque Bacteria Fermentable Carbohydrate Pre-reading ‘Histology of enamel and den5ne’ Lectures Histopathology of Enamel Caries Learning Objec4ves: By the end of the session you will be able to; Describe the clinical appearance of enamel caries Describe the histology of enamel caries Be able to iden5fy and name the 4 zones of destruc5on in enamel caries Be able to describe the clinical appearance of enamel caries in rela5on to its histopathology Recap on Caries Ae4ology As PH lowers, the tooth surface (hydroxyapa5te) will demineralise and break down into its component ions. If the PH does not neutralise, this demineralisa5on over 5me will lead to caries. How do we know this is happening clinically? ICDAS Score The interna5onal ICDAS was A clinical scoring ICDAS allows Developed due to caries detec5on developed for use system used to detec5on of the inconsistencies in and assessment in clinical diagnose caries caries process at caries diagnosis system research, clinical every stage and prac5ce and for characterisa5on epidemiological of the carious purposes ac5vity of the lesion ICDAS Score Sound tooth No evidence of caries when tooth surface is wet No evidence when tooth surface is dry Tooth clinically sound Score 0  Evidence of caries only when tooth is dry Initial stage of caries ICDAS Score Ini5al Stage Caries No evidence when tooth surface is wet ARer air drying Srst visual signs seen White spot and/or brown carious discoloura5on Code 1  Evidence of caries visible when tooth is wet and dry Still initial stages of caries ICDAS Score Ini5al Stage Caries Dis5nct visual changes in enamel Visible when wet and dry Code 2  Moderate stages of carious process Breakdown in enamel surface - not just visual change Visaible when tooth is wet or dry - more obvious when dry If you dry area well you’ll see loss of enamel integrity ICDAS Score Moderate Stage Caries Localised enamel breakdown without visible den5ne exposure Visible when wet and dry Prolonged drying reveals loss of enamel integrity Code 3 How does this apply to the histological appearance? Enamel Caries Microscopic Appearance SEM (scanning electron microscope) Enamel Caries Microscopic Appearance  Every carious process starts with the slight etching of the enamel surface  This occurs under the dental plaque  This occurs frequently and is reversible  The scan to the right shows healthy enamel adjacent to this ‘etched’ enamel Enamel Caries Microscopic Appearance  Under cariogenic circumstances the tooth will dissolve further resul5ng in microporosi5es in the enamel surface Dissolve further  These are typically located at prism boundaries (see earlier lectures) Enamel Caries Micro/macroscopic Appearance Different reflection of light due to different enamel surface  The Srst clinical signs are white spots  These appear white because a greater propor5on of incoming light is being sca[ered compared to the surrounding enamel  This is due to increased porosi5es as the mineral is lost.  The air (or electrolyte) in these porosi5es has a di\erent refrac5ve index to sound enamel This is why we need to dry the teeth - to visually see bettter  Enamel Caries Micro/macroscopic Appearance Porous areas  Where these porosi5es occur, white spot lesions can incorporate exogenous pigmenta5on. This can make the lesion appear brown.  This may suggest that a lesion has been present for a longer period of 5me however, does not guarantee this This is why early enamel caries can sometimes appear brown - picking up of staining causes this to occur Really white enamel caries - likely to be very recent as hasn’t had opportunity to pick up stain, potentially progressing faster than brown stained Brown area - likely been present longer period, generally slower process and happens over longer period of time Established Enamel Caries Histology Established enamel caries (s5ll within enamel, not extending into den5ne) has 4 dis5nct zones Outside of tooth Main body Edge of body of the lesion Extending into the tooth Established Enamel Caries Histology On surface of tooth, in contact with saliva Largest area of enamel lesion - loosing a lot of mineral Part of lesion at the dept of the enamel Not affected due to easy access to saliva and mineral content from acid from bacteria dissolving ions - easier for surface to remineralise hydroxyapatite When we prepare tooth - very little porosity so appears dark on image - dynamic demineralisation and remineralisation as carious process hasn’t fully established Once deeper zones have lost mineral - it is harder to remineralise due to lack of exposed minerals and progress faster  Established Enamel Caries Histology These present as a ‘wedge’ shaped lesion with the point of the wedge towards the den5ne in smooth surface caries and towards the enamel surface in pit and Sssure caries Smooth surface caries - buccal surface - wedge shaped = amount of tooth affected on surface of lesion is greater than amount affected tooth at the depth. (Worse on outside) Pit and fissure caries = small break in cavity as usually difficult to clean at base of pit - progresses faster in enamel surface to form inverted triage. Very little affected enamel at point of entry but becomes extensive into the tooth. What we see in the mouth of pit and fissure caries isn’t representative of the carious process. Established Enamel Caries Histology In order to iden5fy all histological zones, the samples need to be cleared using a clearing agent such as quinoline. This is used commonly as it has an iden5cal refrac5ve index to enamel The classical zones of enamel caries are then iden5Sed due to di\erences in the amount and size of porosi5es. They are iden5Sed using transmi[ed light microscopy Using di\erent clearing mediums of varying op5cal refrac5ve indices with transmi[ed light microscopy or polarised light microscopy, the size of the porosi5es and pore volume can be obtained  1. Surface Zone This is the outermost zone of the lesion Can also be referred to as the intact or pseudo-intact surface It has a rela5vely high mineral content Has a pore volume below 5% Pore volume low as able to remineralise using ions from surrounding plaque and saliva - not very porous The reason the pore volume is lower than deeper areas of the lesion is due to its ability to remineralise. This occurs as this area is in contact with mineral ions in saliva/plaque on its surface  Biggest part of lesion - what we see on radiographs 2. Body of the Lesion This is the zone below this surface zone and makes up the majority of the lesion. This is the area that is visible on conven5onal radiographs This demonstrates porosi5es of a large diameter Pore volume varies from 5-25% Very porous due to a lot of mineral loss Appears translucent with striae of Retzius well marked  3. Dark Zone This is a thin layer below the main body of the lesion Termed the ‘dark zone’ as has small porosi5es which the clearing medium cannot enter and hence appears dark under light microscopy The pore volume is 2-4%Not been much demineralisation at this point of lesion but some changes starting to occur - not very porous Sugges5on of some remineralisa5on in this area Possibly due to lipid and protein presence that may hamper the mineral precipita5on  4. Translucent Zone Deepest within enamel This is the layer at the advancing edge of the lesion This is the ini5al area of destruc5on as part of the carious process This has a pore volume of 1% (sound enamel 0.1%) Very little mineral loss at advancing edge of lesion - not very porous This is due to the early demineralisa5on Ini5al dissolu5on occurs along the gaps between rods Video for review  This video summarises the process. Please view from 4:40 h[ps://www.youtube.com/ watch?v=Y_o0ygwA6CI Thank You!