Histopathology of Dentine 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...

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  Dark shadow from dentine showing through enamel with or without enamel breakdown Once bacteria have got inside tooth and got into dentine - causes discolouration and discolouration that shines through the translucent enamel surface to show clinically as grey surface May be no obvious breaks in enamel surface - can see grey colour underneath pits and fissures which shows caries and discolouration happening underneath in dentine ICDAS Scores May be white or brown spot when wet 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)  Distinct cavity with visible dentine exposure (carious) More breakdown and can see exposed dentine Cavitation in enamel going through to underlying dentine ICDAS Scores White patches around edge of lesion where demineralisation is starting with brown patches due to necrotic tissue at centre of lesion 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 See clinically a huge amount of enamel loss that has broken away due to carious process of dentine underneath - leads to big hole of obvious dentine exposure 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 Enamel more resistant - speed of progression in enamel is slower than dentine Dentine dissolves more readily Difference in progression - extends quicker in dentine - extends laterally underneath enamel Expansion leads to grey shadowing Eventually will become so undermined it will lead to cavitation. 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 As the dentine underneath breaks down underneath enamel, eventually the enamel will be unsupported and will breakdown and become a cavity 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 Bacteria get into dentine and as they release acids they dissolve the dentine and makes it softer as it demineralises Bacterial destruc5on makes the den5ne soZer This can be iden5[ed with a sharp probe but do not try this on the cavity If not cavitation of enamel surface, any undermined enamel will be fragile and you will break away any \oor (why not?) undermined enamel which will lead to a cavity - will become more plaque retentive and more likely more lesion to extend quicker Use ball ended probe or non sharp probe As the caries progresses, the surface becomes heavily infected den5ne which can be ‘peeled away’ with an excavator. This is usually browner in Necrotic tissue colour Below this is less infected den5ne which is harder How does this clinical appearance translate to histological appearance?  Cavitation of enamel More extensive lesion in dentine as progress is faster in dentine Microscopic Den4ne Caries Inverted mushroom, small entrance in enamel and expands out into dentine Small cavity on tooth surface may translate into larger cavity within dentine 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 Outer surface 5 43 2 1 2) Zone of penetra4on 3) Zone of demineralisa4on 6 4) Translucent den4ne 6) Normal dentine A[ected vs Infected Den4ne Infected = bacteria penetrate into dentine and causing destruction Affected = does not have any bacteria within it but still changin from normal healthy dentine. Because bacteria produce byproducts (acids, toxins) diffuses into dentinal tubules and starts to damage underlying dentine. Zone of destruc5on Zone of penetra5on Soft mushy dentine = infected dentine Slightly harder discoloured dentine = affected dentine Zone of demineralisa5on Translucent zone  Zone 1 – Zone of Destruc4on Too damaged for it to repair 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 Lower mineral content 4) Collagen matrix denatured by proteoly5c enzymes Produced by bacteria 5) Bacterial load is very high Large number of bacteria in this area 6) Den5nal tubule structure destroyed Due to bacterial destruction 7) This produces round areas of liquefac5on Area where tubules have been destroyed termed ‘liquefac5on foci’ within the tubules 8) Cracks then form at 90⁰ to the tubules and are termed transverse cleZs Cause breaking away of parts of dentine Zone 1 – Zone of Destruc4on A lot of bacteria within This represents caries infected den5ne and needs to be removed which is easily done with an excavator 1. It cannot be repaired To demineralised 2. Provides poor surface to bond 3. Inability to form a sealDue to poor surface bone 4. Inadequate restora5on support More chance of fracture if on soft base Zone 2 – Zone of penetra4on/bacterial invasion Within this zone the den5nal tubule structure s5ll exists and liquefac5on has not occurred The tubules are however invaded by bacteria Invaded by These decalcify the den5ne with acid With They also dissolve proteins (proteolysis) This is also a layer of caries infected den5ne Infected Generally, most clinicians believe this needs to be removed and can be Believe done so with a rose head bur. When would you not remove this zone? If very little space between If not removed and sealed, if the restora5on fails the bacteria will pulp and lesion and may expose pulp Edges still need to be clear rapidly con5nue the process Remove with rose head and slow hand piece Zone 3 – Zone of demineralisa4on  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 Affected area Starting to see dentine destruction  This is the advancing front of the lesion The base of the lesion  This may be very small (less than 1mm) Zone 3 – Zone of demineralisa4on  This may feel soZer than sound den5ne  This can be repaired by the den5ne pulp complex  May be paler brown in appearance  This is considered caries aWected den5ne  Does not need to be removed As there is no bacteria present Firm demineralised den4ne that does not need to be removed Zone 4 – Translucent (Sclero4c) Zone This happens when acid ini5ally starts to penetrate  The live odontoblast processes start to lay down calci[ca5on within the tubules making them hyper- mineralised Increase calcification - prevent acid penetration  This leads to them becoming ‘plugged’ with mineral Try’s to reduce chance of damage and getting near the pulp  This aims to slow acid and toxin penetra5on and protect the pulp Zone 4 – Translucent (Sclero4c) 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 As shows protective function More dentine thickness here Zone 5 – Ter4ary Den4ne 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 – Ter4ary Den4ne This is produced when the pulp becomes mildly in\amed by advancing acid It has an irregular tubular structure and comes in 2 diWerent types Reac4onary Den4ne 1) Deposited as a result of a mild irritant Normal dentine like structure 2) Originates from surviving upregulated odontoblasts Repara4ve Den4ne 1) Deposited as a result of a strong irritant 2) Local cell death in the odontoblast layer Stem cells try to produce dentine in irregular form to protect pulp 3) Odontoblast like cells form which produce a much more irregular den4ne structure Zone 5 – Ter4ary Den4ne  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 hhps://www.youtube.com/ watch?v=Y_o0ygwA6CI Thank You!