Cariology

Question 1

Define root caries and describe the pharmacological methods available to treat root caries (7 marks)

Answer 1

Root caries: carious lesion located on the root surface (cementum) of a tooth, close to or below the CEJ towards the apex of the tooth

Pharmacological agents:
Fluoride e.g. mouthwash, varnish and gel
Chlorhexidine e.g. mouthwash and varnish
Triclosan toothpaste
Chlorhexidine and thymol

Question 2

A patient is worried about mottling with fluoride use, how would you advice them? (5 marks)

Answer 2

Mottling occurs is caused by hypo-mineralisation of enamel due to excessive fluoride intake during enamel formation
 Mottling appears as white chalky patches on tooth, which can stain

Advice:
 Recommend use the recommended fluoride concentration toothpaste for age
 Brush twice daily with correct amount of fluoride toothpaste for age e.g. pea sized for adult
 White chalky areas on tooth/staining, can be removed by attition/abrasion
 Only use mouthwash if > 8 years old that is high risk

Question 3

Describe ONE method of topical fluoride and how you would apply this (6 marks)

Answer 3

 Apply a very small quantity (0.25 mL, especially in young children)
 Dry tooth with cotton wool roll/3 in 1 syringe, and apply to tooth surface
 Apply with microbrush to pits, fissures, approximal surface of white spot lesions
 Patient should avoid eating, drinking or brushing for 30 minutes
 Only eat soft foods for next 4 hours
• Ensure patient does not swallow varnish
• Keep record of how many times patient has had varnish this year, limit to 2 for patient without special needs (3-4)

Question 4

Describe ONE method the patient can use at home to increase topical fluoride (2 marks)

Answer 4

 In addition to fluoride toothpaste (135-1500 ppm) prescribing the use of fluoride rinses (> 8 years old)
 Fluoride rinse e.g. sodium fluoride mouthrinse - 0.05% NaF

Question 5

What advice would you give on using this method? (2 marks)

Answer 5

 Use at a different time to toothbrushing to maximise topical effect - rinsing after brushing will reduce antibacterial effects of fluoride toothpaste
 Use daily, rinse for 1 minute then spit out

Question 6

Describe some emergency advice you would give (2 marks)

Answer 6

Describe some emergency advice you would give (2 marks)
 Do not swallow, make sure to spit out mouthrinse following use
 Small amount swallowed not cause for concern
 If large amount swallowed seek medical help and also check label of mouthwash for any particular poisonious substances
 Milk, calcium gluconate (1%) and vomiting

Question 7

List five sources of fluoride ion available in the UK (5 marks)

Answer 7

• Tap water
• Salts or tablets
• Toothpaste
• Fluoride varnish
• Fluoride mouthwash/gels/solutions

Question 8

Briefly describe how fluoride is thought to prevent dental caries (5 marks)

Answer 8

• Replaces OH in HAP, forming FAP, which makes makes enamel more acid resistant - requires lower pH for demineralisation - ca10(po4)6(oh)2 –> ca10(po4)6(F)2

Pre-eruptive
 Reduces demineralisation by incorportation of F- into developing enamel, increasing size of apatite crystals, the larger crystals dissolve more slowly

Post-eruptive
 Encourages remineralisation by incorporation of F- into surface enamel, plaque fluid and altering plaque microbial composition
• F- stops bacterial glycolysis by decreases the hydrogen gradient across the membrane, stopping ATPase activity

Question 9

At what stage in an individuals life are systemic fluorides considered useful in a caries prevention programme? (2 marks)

Answer 9

 Medically compromised that cannot use topical fluoride at home
 Patients who are at high risk of caries who’s primary drinking water has low fluoride concentration (> 6 months)

Question 10

What is dental (enamel) fluorosis? (4 marks)

Answer 10

 Fluorosis (mottling) is caused by hypomineralisation of tooth enamel caused by excessive fluoride ingestion during enamel formation
 Appears as a range of visual changes in enamel, ranging from mild to severe
- Mild - white opaque areas over tooth (white chalky appearance)
- Moderate - more extensive mottling
- Severe - brown discolouration and pitting

Question 11

What is the aetiology of fluorosis? (4 marks)

Answer 11

 Excessive fluoride consumption
 Ingestion of fluoride toothpaste/using too much
 Swallowing fluoride mouthwash
 Genetic factors

Question 12

Explain THREE principles of caries prevention in children and the rationale behind them? (6 marks)

Answer 12

 Primary: stopping disease in the first place i.e. keeping teeth healthy before disease occurs
 Secondary: detecting disease and preventing further development of disease i.e. limiting the impact of disease at an early stage - radiographs, PRR, approximal/cervical caries confined to caries (OHI, fluoride & diet)
 Tertiary: treating disease, restoring function and preventing further development of disease - extractions, restorations and all of secondary

Question 13

Outline what methods can be used to prevent caries in children? (14 marks)

Answer 13

1. Diet analysis
    Carried out using diet sheet (chart) over 4 days (24 hrs if 4 not possible)
    Analyse diet with patient/carer
    Identify sugar frequency (aim < 4), intake (aim < 10% daily calories), acidic drinks/foods (educate on effects on tooth loss and recommend straw use)
    Offer alternatives e.g. sweetners as a substitute for sugar
    Advise against snacking and encourage healthy well-balanced diet
    Could recommend sugar free gum between meals
   - Use straw with fizzy drinks
   - Try not eat before bed, and wait 30 minutes before brushing
2. Oral hygiene instruction
    Brushing 2 x day (last thing at night and another time)
    Spit do not rinse
    Fluoride toothpaste (1350 -1500 ppm, may vary depending on caries risk)
    Systematic approach, 2 minutes per quadrant
    Modified bass technique
    If < 7 y/o supervise brushing
3. Fluoride
    Fluoride varnish 2 x a year 2.2% F (3-4 x high caries risk)
    Fluoride mouthrinse > 8 y/o (0.05 % NaF)
    Fluoride toothpaste (strength varies depending on caries risk and age)
4. Others: fissure sealing (usually 1st permanent molars), patient motivation, smoking cessation, alcohol,

Question 14

What are the advantages of local anaesthetic over a general anaesthetic? (5 marks) 


Answer 14

 Patient is still conscious
 Cheaper
 Safer with less risks, deaths and precautions for use
 Less experienced staff required e.g. anaesthetist
 Fewer complications

Question 15

Name 4 constituents of a local anaesthetic and describe the role of one of them (5 marks)

Answer 15

 LA agent - e.g. Lidocaine, prilocaine etc - exerts pharmacological action –> removal of pain sensation
 Vasoconstrictor e.g. adrenaline, felypressin - reduces systemic absorption, increases duration of action, allows higher doses of LA and bleeding
 Reducing agents - prevent oxidation of vasoconstrictor
 Saline solution - Ringer’s solution
 Preservatives

Question 16

Give 5 reasons why a local anaesthetic may fail (5 marks)

Answer 16

 Injecting into the wrong site (wrong nerve, IM, IV)
 Inflammation at the injection site, resulting in increased acidity, therefore increasing ionised fraction of LA reducing mechanism of action pharmacologically
 Injecting too little solution (too little volume)
 Not high enough concentration
 Infection at site
 Use of wrong LA technique for tooth (clinical scenario) e.g. infiltration for mandibular molars where cortical bone is thick therefore LA cannot penetrate into bone & diffuse into it
 Injecting an inappropriate solution

Question 17

What equipment and materials do you need to give a local anaesthetic to a patient? Explain the reason for each item (8 marks)

Answer 17

 Syringe - to administer LA (black not disposable, white disposable)
 Needle - to penetrate tissues and deposit LA into site of action
 LA cartridge - contains LA agent, vasoconstricters, reducing agent, saline solution, preservatives, which has the pharmacological effect
 Safety syringe/sheath - to cover needle and prevent needlestick injury during use
 Topical anaesthetic - e.g. 20% benzocaine to reduce anaesthetise soft tissues, reducing pain for patient when piercing tissues and psychological reasons for anxiety, pain

Question 18

What local anaesthetic would you give to:
an older patient who has well controlled hypertension (1 mark) 
an anxious patient who had an unsuccessful local anaesthetic the day before. (1 mark)

Answer 18

 Prilocaine with felypressin
 Articaine with felypressin

Question 19

What is diet analysis and how is it performed?

Answer 19

 Assessment of patient’s diet to identify potential dietary causes of tooth decay
 Focusing on sugar frequency, intake, acidic foods and habits such as snacking - may lead to poor oral hygiene
 Carried out using a diet sheet, where patient charts what they eat over 4 days (24 hrs if find it difficult) to include all meals, drinks and additional sugars

Question 20

What do you look for in a diet analysis?

Answer 20

 Sugar frequency and amount
 Acidic foods
 Tea/coffee and additional sugars added to these
 Snacking and general balance of diet e.g. good sources of carbohydrates, protein, fats etc
 Water consumption

Question 21

What would you modify in someone’s diet?

Answer 21

 All of the above reduced
 Sugar attacks < 4 a day, with < 10% of daily caloric intake recommended in UK
 Offer alternatives to sugar e.g. sweetners etc
 General balanced diet

Question 22

How else would you prevent caries in a patient?

Answer 22

 Oral hygiene instruction - brushing advice, flossing etc
 Fluoride - varnish, toothpaste, mouthwashes
 Fissure sealants and patient motivation

Question 23

Why are older patients more likely to have caries?

Answer 23

 Xerostomia - due to reduced salivary gland function and potentially polypharmacy, use of several medications that cause dry mouth
 Medical factors e.g. systemic conditions
 Denture use, reduced dexterity and poor oral hygiene

Question 24

80 year old women presents with root caries. Describe 3 risk factors for this and why it increases the risk. (6)

Answer 24

 Saliva (xerostomia) - flushing action and buffer action deminished therefore –> caries
 Oral hygiene and reduce dexterity - poor oral hygiene increase in plaque, leads increase in amount of cariogenic organisms such as S.mutans –> caries
 Denture use –> if not cleaned properly may be a good environment to harbour bacteria and grow
 Dietary –> e.g. large intake of sugar provides substate for cariogenic bacteria e.g. S.mutans and lactobacillus –> convert to acid –> caries
 Root exposure due to gingival recession - dentine has higher critical pH than enamel, with demineralisation occuring at pH 6.5

Question 25

Define tertiary dentine and the two types of tertiary dentine (2 marks)

Answer 25

 Tertiary dentine is produced in response to an external stimuli e.g. attrition, caries, cavity preparation, microleakage around restorations or trauma, amongst others. It has a protective role  There are two types: Reactionary and reparative dentine.

Question 26

Describe the differences between the two types of tertiary dentine (4 marks)

Answer 26

 The grade of stimulus dictates whether reactionary or reparative dentine is formed  Mild injury (low-grade stimulus) e.g. shallow carious lesions or mild tooth wear (erosion) stimulates the depostion of reactionary dentine (reactionary detinogenesis) from pre-existing odontoblasts  Extensive injury (high-grade stimulus) e.g. advanced carious lesion with pulp exposure stimulates the deposition of reparative dentine (reparative detinogenesis) from newly differentiated odontoblast-like cells (OLCs) from progenitor cells in the cell rich layer of pulpal tissue, due to death of original odontoblasts as a result of the stimulus

Question 27

Describe the stepwise excavation technique (6 marks)

Answer 27

Describe the stepwise excavation technique (6 marks)  Stepwise excavation: Method of managing deep carious lesions to reduce risk of pulpal exposure/pathology by removing caries lesion in separate appointments with > 6 month intervals with the aim of dentine-pulp complex laying down reparative dentine to reduce risk to pulp  Process: Gain access, clear EDJ (periphery caries free), leave deeper caries over pulp, place Ca(OH)2 lining and fill with provisional zinc polycarboxylate restoration then re-access after 6-9 months (tertiary dentine - reparative has laid down), remove infected (but arrested) caries and place definitive restoration

Question 28

Why do diagnose caries (3 marks)

Answer 28

 Eradicate disease, prevent complications and maintain general well-being  Reversible in it's early stages  Prevent pain and suffering - if caries reaches pulp  Avoid infection - that follows caries exposure to pulp chamber, root canals and peri-radicular tissues

Question 29

2 patients, both siblings. When you do a plaque distribution chart on them you find a similar distribution of plaque with a score of 60% on both. However on radiographic examination, you find only one has caries. A study has shown the undeniable link between caries and plaque. What does this clinical scenario show you? (6 or 8 marks)

Answer 29

• Caries is multi-factorial disease • Requires: time, bacteria and host (immune responses and diet) • Plaque forms on a clean tooth surface immediately after tooth brushing, with an aquired pellicle forming within 2 hours. • Composed of bacterial and host salivary components • Bacteria within the plaque including: strep. mutans, lactobacilli produce dental caries due to a disruption in the homeostasis of the oral environment. • Each sibling may have been exposed to different environmental factors which causes bacteria in the plaque to become pathogenic and produce acid which leads to acid. • Radiography may not always detect caries

Question 30

What is considered as retention?

Answer 30

Property of cavity/restoration to resist displacement in the direction of insertion

Question 31

What is considered as resistance?

Answer 31

Property of cavity/restoration to prevents displacement in apical & oblique directions i.e. any other direction

Question 32

What types of additional retention exist?

Answer 32

• Undercuts • Grooves and slots • Pins • Enamel bevelling

Question 33

Where should a slot/groove be placed and at what depth?

Answer 33

0.5-1 mm depth in gingival/axial walls

Question 34

List THREE ways in which fluoride can be deposited in enamel mineral (6 marks)

Answer 34

Fluoride in blood: enamel deposition and calcification - Fluoride in tissue fluid: enamel maturation - Fluoride in saliva and GCF: eruption into oral environment

Question 35

What is an alternative technique to Stepwise excavation

Answer 35

Atraumatic restorative technique • Procedure: - Access caries - Remove all caries infected dentine (using excavator) - Leave deeper caries over pulp - Place provisional GIC restoration: Allows for remineralisation caries affected dentine - Place restorative material using sandwich restoration technique • Reasons for use: - No need for re-entry into cavity - Reduces number of appointments - Just as effective as step-wise

Question 36

What clinical features can indicate the failure of a restoration? (5 marks)

Answer 36

1. Secondary/recurrent caries 2. Loss of function − Loss of restoration − Loss of surrounding tissue 3. “Inevitable” progression to caries 4. Microleakage causing sensitivity or pain 5. Appearance unacceptable to patient e.g. discolouration

Question 37

List the symptoms of secondary/recurrent caries (3 marks)

Answer 37

• May be asymptomatic • Tooth discolouration (anterior) • If pulpal involvement may lead to symptoms of pulpitis e.g. pain and inflammation

Question 38

How can you detect the presence of recurrent caries? Take account of the different sites on the tooth where it may occur (4 marks)

Answer 38

• Same way you would detect any caries − Tactile − Visual − Diagnodent − Dyes − Electronic caries monitor − Radiographs (e.g. approximal using horizontal bitewings – may not always appear) − Loss of vitality on sensibility testing +/- peri-radicular change − Look for signs of micro-leakage • Location – interface between restoration and tooth surface, approximal or within the restoration itself

Question 39

Briefly describe TWO errors in planning and TWO errors in execution the dentist might make that could predispose to failure of a restoration (8 marks)

Answer 39

Errors in planing − Failure to promote prevention e.g. brushing − Failure to check occlusion before management of tooth − Inappropriate restoration for tooth or situation − Inappropriate material (including lining or base) • Errors in execution − Damage to dentine pulp complex: overcutting, excessive heat, excessive pressure − Leaving infected carious tissue − Unsatisfactory cavity design for restorative material − Failure to use matrix properly causing over/under contoured restorations

Question 40

List four factors that may result in failure of restoration

Answer 40

• Patient factors e.g. cariogenic factors unchanged (diet, plaque, xerostomia/saliva, poor OH), para-functional habits and unacceptable appearance • Operator factors e.g. errors in planning and execution (refer to question above) • Material factors e.g. corrosion, wear, discolouration and fracture • Chance e.g. trauma

Question 41

List auxiliary retentive modifications

Answer 41

• Made solely in dentine e.g. axial wall of cavity preparation, care to avoid pulp • Coves • Vertical grooves • Horizontal slots

Question 42

What instruments would you use to prepare a mesio-occulsal UR6 cavity?

Answer 42

• 330/diamond bur face handpiece to gain access • Rose head bur slow handpiece remove caries (or excavator) • BPE and straight probe (to remove excess material) • Burnisher (shape matrix probe and burnish amalgam) • Carver to create fissure pattern • Mirror

Question 43

What special features would you carry out for the cavity preparation for it to receive amalgam

Answer 43

• Undercuts • Grooves and slots • Flat surfaces • 90 degree cavo-surface angle • Rounded internal line angles • Can also use pins for additional retention • 2 mm depth

Question 44

Describe the steps in placing this material in the mouth and steps you would carry out?

Answer 44

Matrix band placement: blue for adult, green for children - Wedge placement to secure matrix band: ensure in correct direction, base of triangle placed against gingival margin - Burnish matrix band to re-establish contact point - Titrate amalgam in amalgamator - Take up amalgam in amalgam plugger, place in cavity - Condense amalgam using adequate pressure, to avoid voids - Use amalgam carver to reform morphology and marginal ridge - Use straight probe around matrix band to match anatomy of marginal ridge - remove matrix band and floss between tooth - Use cotton wool with water to remove excess amalgam - Polish 24 hours later - Check occlusion with GHM paper

Question 45

What is dental caries, aetiology of caries and what bacteria are involved, and which acids are produced?

Answer 45

• Loss of tooth substance by metabolically produced acids from bacteria in the mouth • Caries is a multifactorial disease influenced by factors such as saliva, host factors, time, bacteria, diet (sugar) amongst others Bacteria: • Strep mutans • Lactobacillus • Fusobacterium • Actinomyces • Prevotella Acids produced: • Lactic acid (main acid associated with caries) • Acetic acid

Question 46

Define: erosion, attrition, abrasion and abfraction

Answer 46

• Erosion: tooth wear caused by acid dissolution from intrinsic or extrinsic acids e.g. stomach acid in bulimia or dietary acids from juices etc, respectively - mainly on labial/palatal surfaces of anteriors and occlusal of lower molars • Attrition: mechanical wear to excessive tooth-to-tooth contact e.g. bruxism - seen on incisal and occlusal edges of teeth • Abrasion: physical wear of tooth substance caused by exogenous substances mainly affecting neck area buccally of anteriors • Abfraction: transmission of forces from cusp tip to thinner cervical enamel which causes enamel at this stressed area to fracture away

Question 47

What is considered under demineralisation? Carious lesions zones

Answer 47

• Dissolution of enamel surface (HAP) releasing Ca2+, Po42- and other ions, which can result in a frosted-white appearance of tooth • Zone of destruction - enamel cavitated and bacteria infect dentine • Zone of bacterial invasion - bacteria enter dentinal tubules, produce acid and dissolve HAP and collagen moving towards pulp • Zone of demineralisation - acid produced by bacteria moves down tubules, no bacteria in these regions • Translucent zones - tubular sclerosis - mineral deposition in tubules to prevent ingress of invading bacteria to protect dentine-pulp complex • Reactionary dentine - in response to the stimuli dentine deposition, low grade - slow and regular, high-grade - rapid and irregular, pulpal inflammation (pulpitis)

Question 48

What is dental plaque and how is if formed?

Answer 48

• Complex microbial community embedded in a matrix of salivary and bacterial origin (biofilm) found on the tooth surface Formation: 1. Acquired enamel pellicle - Deposited on clean tooth surface immediately, composed of proteins, glycoproteins, lipids derived from salivary, GCF and bacteria e.g. proline-rich proteins (host) and glucans/fructans (bacteria) - host and bacterial components act as receptors for bacterial adhesion 2. Pioneering species - adhere to acquired pellicle e.g. Streptococcus mitis, oralis 3. Pioneering species multiply to form a confluent layer - co-aggregations occur e.g. fusobacterium with oral streps and actinomyces 4. Accumulated bacterial growth - reduced oxygen tension, growth of anaerobic bacteria and increased diversity 5. Plaque maturity - mature dental plaque formed (climax community)

Question 49

What is a white spot lesion and how does it look?

Answer 49

• Early sign of caries, first sign visible to naked eye, usually visible with strong white light - caused by subsurface demineralisation of enamel • Milky appearance (opacity)

Question 50

What is remineralisation

Answer 50

Process in which Calcium ions (CA2+) hydrogen phosphate (PO42-) in saliva allows for these to be incorporated into (demineralised) Hydroxyapatite (HAp)

Question 51

Why is remineralisation of enamel possible and which lesions can be remineralised?

Answer 51

• White spot lesions - early sign of caries, visible to naked eye, usually with strong white light • Presence of Ca2+ and PO42- in saliva allows for these to be incorporated into (demineralised) HAP

Question 52

Types of carious lesions: primary, secondary, residual, active, arrested, white spot, brown spot and rampant

Answer 52

Primary caries = lesion on unrestored tooth surface Secondary (recurrent) caries = adjacent to fillings (due to microleakage) Residual caries = demineralised tissue left behind before a filling is placed Active caries = considered to be progressive Arrested caries = No longer progressing White spot lesion = first sign of caries visible to naked eye, usually visible with strong white light Brown spot lesion = usually an inactive white spot lesion discoloured by uptake of dye Rampant caries = multiple active carious lesions in same patient Hidden caries = usually in dentine and only detectable by radiographs

Question 53

What is the dentine reaction to caries?

Answer 53

• Tubular sclerosis - process of mineral deposition in dentinal tubules - Aim to block tubules in order to prevent ingress of bacteria to protect dentine-pulp complex • Reactionary dentine - tertiary dentine produced in response to external stimuli e.g. attrition, caries, cavity preparation etc, has a protective role, produced from pre-existing odontoblasts • Pulpitis - increase blood flow, oedema and migration of inflammatory cells (neutrophils, lymphocytes, plasma cells, macrophages

Question 54

What is most common site for caries?

Answer 54

• Most common at pits and fissures and inter-proximal