Histopathology of Enamel Caries 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 I The interna5onal caries detec5on ICDAS was developed for use A clinical scoring system used to ICDAS allows detec5on of the Developed due to 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 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 ICDAS Score Ini5al Stage Caries Dis5nct visual changes in enamel Visible when wet and dry Code 2 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  These are typically located at prism boundaries (see earlier lectures) Enamel Caries Micro/macroscopic Appearance  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 Enamel Caries Micro/macroscopic Appearance  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 Established Enamel Caries Histology Established enamel caries (s5ll within enamel, not extending into den5ne) has 4 dis5nct zones Established Enamel Caries Histology Loosing lots of In contact with saliva mineral content due to acid.  Smooth surface caries - highlight sizes Established Enamel Caries Histology of various lesion Pit/ fissure caries small opening but larger at the base. Less clinically than 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 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% 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  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% 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% Sugges5on of some remineralisa5on in this area Possibly due to lipid and protein presence that may hamper the mineral precipita5on  4. Translucent Zone 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%) 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!