Histopathology of Dentine 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...

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 Suscep4ble tooth surface Caries ‘Ae5ology of Dental Caries’ Lecture Time Plaque Bacteria Fermentable Carbohydrate Pre-reading ‘Histology of enamel and den5ne’ Lectures Histopathology of Den4ne Caries Learning Objec4ves: By the end of the session you will be able to;  Describe the clinical appearance of den5ne caries  Describe the histology of den5ne caries  Be able to iden5fy and name the 4 zones of destruc5on in den5ne caries  Be able to iden5fy mechanisms that the den5ne uses to protect itself and the pulp from assault 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 Scores The interna5onal caries detec5on and assessment system ICDAS was developed for use in clinical research, clinical prac5ce and for epidemiological purposes A clinical scoring system used to diagnose caries ICDAS allows detec5on of the caries process at every stage and characterisa5on of the carious ac5vity of the lesion Developed due to inconsistencies in caries diagnosis S4ll however has an element of subjec4vity ICDAS Scores Moderate Stage Caries Dark shadow from den5ne with/without enamel Code 4 breakdown White or brown spot when wet Darkened area of intrinsic shadow (grey, blue, brown) ICDAS Scores Extensive Stage Caries A dis5nct cavity in opaque or discoloured enamel with visible den5ne Code 5 Visible evidence of demineralisa5on (white or brown walls) ICDAS Scores Extensive Stage Caries An extensive cavity Visually able to see extension Code 6 into den5ne Recap on the Structure of Den4ne The mineral component of den5ne is hydroxyapa5te Organic material is collagen This is a vital 4ssue as the den5nal tubules are permeated with the cell process of the odontoblasts It therefore is able to defend itself from assault (alongside the pulp) We refer to this as the den5nal-pulp complex as the 2 5ssues are in5mately related So how does den4ne caries progress through each stage to give these ICDAS scores? Macroscopic Den4ne Caries – ICDAS Code 4 Progression from enamel to den5ne demonstrates a change in the hardness of the substrate This causes a lateral spread of caries under the enamel This leads to grey shadowing This eventually leads to breakdown in the crown integrity  Macroscopic Den4ne Caries – ICDAS Code 4 This is similar to the erosion of a cliW with bacteria being represented by the water Macroscopic Den4ne Caries – ICDAS Code 5/6 As the enamel becomes further undermined it breaks away This leads to den5ne exposure (ICDAS 5) and eventually an extensive cavity (ICDAS 6) The more destruc5on, the more diYcult to restore Macroscopic Den4ne Caries – ICDAS Code 5/6 Bacterial destruc5on makes the den5ne soZer This can be iden5[ed with a sharp probe but do not try this on the cavity \oor (why not?) As the caries progresses, the surface becomes heavily infected den5ne which can be ‘peeled away’ with an excavator. This is usually browner in colour Below this is less infected den5ne which is harder How does this clinical appearance translate to histological appearance? Microscopic Den4ne Caries Note this now shows as a ‘mushroom’ shape (di[erent to enamel caries) This sample demonstrates the ‘undercuVng’ of enamel as caries progresses along the ADJ through soXer den4ne  Microscopic Den4ne Caries th The macroscopic appearance discussed matches to 4 key zones of the lesion. In addi4on, a 5 zone (ter4ary den4ne) is noted away from the lesion Microscopic Den4ne Caries As these areas cannot be observed clinically, these can also be de[ned as caries ‘aWected’ and ‘infected’ zones 1) Zone of destruc4on 5 43 2 1 2) Zone of penetra4on 3) Zone of demineralisa4on 6 4) Translucent den4ne 6) normal dentine  A[ected vs Infected Den4ne Affected dentine no bacteria present but still Infected dentine bacteria has penetrated and causing destruction. changing , because bacteria causes byproducts that defuses into underlying dentine. Zone of destruc5on Zone of penetra5on Infected dentine Zone of demineralisa5on Translucent zone Affected dentine  Zone 1 – Zone of Destruc4on The outermost, super[cial, irreparable, necro5c area of destruc5on clinically as dark brown, soZ and mushy 1) With rapid caries this may be soZ and yellow 2) With slowly progressing caries is harder and browner 3) Mineral content is dissociated due to bacterial acid 4) Collagen matrix denatured by proteoly5c enzymes 5) Bacterial load is very high 6) Den5nal tubule structure destroyed 7) This produces round areas of liquefac5on termed ‘liquefac5on foci’ within the tubules 8) Cracks then form at 90⁰ to the tubules and are termed transverse cleZs Zone 1 – Zone of Destruc4on This represents caries infected den5ne and needs to be removed which is easily done with an excavator 1. It cannot be repaired 2. Provides poor surface to bond 3. Inability to form a seal 4. Inadequate restora5on support Zone 3 – Zone of demineralisa0on  Acid produced in the higher zones spreads down the un-occluded den5nal tubules  This acid easily demineralises the den5ne  No bacteria are present in this area  This is the advancing front of the lesion  This may be very small (less than 1mm) Zone 3 – Zone of demineralisa0on  This may feel so@er than sound den5ne  This can be repaired by the den5ne pulp complex  May be paler brown in appearance  This is considered caries aCected den5ne  Does not need to be removed Firm demineralised den0ne that does not need to be removed Zone 4 – Translucent (Sclero0c) Zone This happens when acid ini5ally starts to penetrate  The live odontoblast processes start to lay down calciDca5on within the tubules making them hyper- mineralised  This leads to them becoming ‘plugged’ with mineral  This aims to slow acid and toxin penetra5on and protect the pulp Zone 4 – Translucent (Sclero0c) Zone  This may show radiographically as a whiter area below the caries  This is due to the hyper mineralisa5on  This area does not need to be removed Zone 5 – Ter0ary Den0ne Is not truly considered a zone as it is not within the lesion however it is a part of the process This is new den5ne that is laid down at the pulp-den5ne border away from PULP the lesion itself This is laid down to create more den5ne between the pulp and the lesion to give the pulp protec5on Zone 5 – Ter0ary Den0ne This is produced when the pulp becomes mildly inIamed by advancing acid It has an irregular tubular structure and comes in 2 diCerent types Reac0onary Den0ne 1) Deposited as a result of a mild irritant 2) Originates from surviving upregulated odontoblasts Repara0ve Den0ne 1) Deposited as a result of a strong irritant 2) Local cell death in the odontoblast layer 3) Odontoblast like cells form which produce a much more irregular den0ne structure Zone 5 – Ter0ary Den0ne  6 1. Zone of destruc5on 5 2. Zone of penetra5on 4 3. Zone of demineralisa5on 3 4. Translucent den5ne 2 1 5. Ter5ary den5ne 6. Normal den5ne Video for Review  This video summarises the process. Please view from 4:40 hTps://www.youtube.com/ watch?v=Y_o0ygwA6CI Thank You!