ORE Part 1 Dental Exam — Questions and Answers

Question 1: What is the 'intrapulpal injection' technique and when is it used in dentistry?

Only used in general anaesthesia settings
Direct injection of local anaesthetic into the exposed pulp chamber — used as a last resort supplement when all other techniques fail, effective but extremely painful to administer requiring counter-pressure (Correct answer)
Used for routine restorations
A standard first-line injection technique

Correct answer: Direct injection of local anaesthetic into the exposed pulp chamber — used as a last resort supplement when all other techniques fail, effective but extremely painful to administer requiring counter-pressure

Intrapulpal injection delivers LA directly into the root canal/pulp chamber using slow counter-pressure, providing profound anaesthesia even in inflamed pulp. It is painful to administer but immediately effective, used when all other supplemental techniques have failed.

Question 2: Which drug should be available in every UK dental practice for the management of anaphylaxis?

Salbutamol
Adrenaline (epinephrine) (Correct answer)
Hydrocortisone
Chlorphenamine

Correct answer: Adrenaline (epinephrine)

Adrenaline (epinephrine) 1:1000 for intramuscular injection is the most critical drug in anaphylaxis management and must be available in every dental practice as per Resuscitation Council (UK) guidelines. While hydrocortisone and chlorphenamine are adjunctive treatments, adrenaline is the life-saving first-line drug.

Question 3: What is the advantage of nystatin over fluconazole for treating oral candidiasis?

Nystatin has a broader antifungal spectrum
Nystatin is more potent than fluconazole
Nystatin is not absorbed systemically and acts topically, avoiding drug interactions (e.g., with warfarin, statins) while fluconazole is systemic and has significant interactions (Correct answer)
Fluconazole can only be used topically

Correct answer: Nystatin is not absorbed systemically and acts topically, avoiding drug interactions (e.g., with warfarin, statins) while fluconazole is systemic and has significant interactions

Nystatin (polyene antifungal) acts locally in the mouth without systemic absorption. Fluconazole (triazole) is systemic — it inhibits CYP enzymes and has clinically important interactions with warfarin, statins, and other drugs.

Question 4: Which radiographic technique is used to assess the alveolar crest bone level in periodontal disease?

Horizontal bitewing radiographs (Correct answer)
Dental panoramic tomograph only
Periapical radiographs alone
Lateral skull radiograph

Correct answer: Horizontal bitewing radiographs

Horizontal bitewing radiographs are the gold standard for assessing alveolar bone levels in the premolar and molar regions, clearly showing the interdental crest bone height relative to the cemento-enamel junction.

Question 5: What is the clinical indication for prescribing aciclovir in dentistry?

Fungal infections of the oral mucosa
All aphthous ulcers regardless of aetiology
Primary herpetic gingivostomatitis (HSV-1) — aciclovir 200 mg five times daily for 5 days, ideally started within 72 hours of onset, especially in immunocompromised patients (Correct answer)
Routine prevention of cold sores

Correct answer: Primary herpetic gingivostomatitis (HSV-1) — aciclovir 200 mg five times daily for 5 days, ideally started within 72 hours of onset, especially in immunocompromised patients

Aciclovir (guanosine analogue inhibiting viral DNA polymerase) is indicated for primary herpetic gingivostomatitis, particularly in immunocompromised patients or severe presentations. Early initiation within 72 hours maximises benefit.

Question 6: What is the annual occupational dose limit for whole body radiation exposure for a classified dental worker?

50 mSv in any single year with 100 mSv over 5 years
20 mSv per year (whole body effective dose limit under IRR17) (Correct answer)
1 mSv per year
100 mSv per year

Correct answer: 20 mSv per year (whole body effective dose limit under IRR17)

IRR17 sets the annual occupational whole-body effective dose limit at 20 mSv. Classified workers are those whose dose exceeds 6 mSv/year or 3/10 of the dose limit. In dental practice, doses are typically well below this limit.

Question 7: What is the mode of inheritance of dentinogenesis imperfecta?

Multifactorial with no single gene
Autosomal recessive
X-linked recessive
Autosomal dominant — caused by mutations in DSPP (dentin sialophosphoprotein) gene (Correct answer)

Correct answer: Autosomal dominant — caused by mutations in DSPP (dentin sialophosphoprotein) gene

Dentinogenesis imperfecta (DI types II and III) is inherited as autosomal dominant. It is caused by mutations in the DSPP gene. Affected teeth appear grey-blue/amber with bulbous crowns and obliterated pulp chambers.

Question 8: Which antibiotic can reduce the efficacy of the combined oral contraceptive pill?

Amoxicillin reliably reduces OCP efficacy
All antibiotics reduce OCP efficacy
Current evidence suggests ONLY enzyme-inducing antibiotics (e.g., rifampicin) reduce OCP efficacy — broad-spectrum antibiotics no longer considered to do so per FSRH 2019 guidance (Correct answer)
Only metronidazole reduces OCP efficacy

Correct answer: Current evidence suggests ONLY enzyme-inducing antibiotics (e.g., rifampicin) reduce OCP efficacy — broad-spectrum antibiotics no longer considered to do so per FSRH 2019 guidance

FSRH updated guidance (2019): non-enzyme-inducing antibiotics (amoxicillin, metronidazole, etc.) do not significantly reduce OCP efficacy. Only enzyme inducers (rifampicin, some anticonvulsants) require additional contraceptive precautions.

Question 9: What legislation governs radiation protection in the UK dental environment?

The Health and Safety at Work Act 1974 alone
Ionising Radiations Regulations 2017 (IRR17) and Ionising Radiation (Medical Exposure) Regulations 2017 (IR(ME)R 2017) (Correct answer)
The Medicines Act 1968
The NHS Act 2006

Correct answer: Ionising Radiations Regulations 2017 (IRR17) and Ionising Radiation (Medical Exposure) Regulations 2017 (IR(ME)R 2017)

UK dental radiation is governed by IRR17 (protecting workers and the public) and IR(ME)R 2017 (governing medical exposures of patients). Both must be complied with simultaneously in any dental radiographic practice.

Question 10: What is the role of tricyclic antidepressants (TCAs) in managing neuropathic orofacial pain?

TCAs (e.g., amitriptyline, nortriptyline) reduce central sensitisation and modulate descending pain inhibition — effective in low doses (10–75 mg) for neuropathic pain independently of antidepressant effect (Correct answer)
TCAs only work for pain in depressed patients
TCAs act by stimulating endogenous opioids only
TCAs are contraindicated in all orofacial pain management

Correct answer: TCAs (e.g., amitriptyline, nortriptyline) reduce central sensitisation and modulate descending pain inhibition — effective in low doses (10–75 mg) for neuropathic pain independently of antidepressant effect

Low-dose TCAs (amitriptyline 10–25 mg nightly) are first or second-line for neuropathic pain (PDAP, burning mouth, post-herpetic neuralgia). They modulate descending pain inhibitory pathways and reduce central sensitisation.

Question 11: Which suture material is most commonly used for intraoral wound closure following surgical extraction?

Stainless steel wire
Silk (non-resorbable)
Nylon (non-resorbable)
Polyglycolic acid (resorbable) (Correct answer)

Correct answer: Polyglycolic acid (resorbable)

Resorbable sutures such as polyglycolic acid (Vicryl) are most commonly used for intraoral closure as they do not require a separate removal appointment and are broken down by hydrolysis. Silk, while still used, harbours bacteria and is non-resorbable, requiring removal at review.

Question 12: Which drug interaction is relevant when prescribing metronidazole to a patient on warfarin?

Metronidazole inhibits CYP2C9 increasing warfarin levels and INR — bleeding risk increases significantly; warfarin dose reduction and INR monitoring required (Correct answer)
Metronidazole reduces warfarin efficacy
Only relevant if metronidazole is given for more than 10 days
No interaction — safe combination

Correct answer: Metronidazole inhibits CYP2C9 increasing warfarin levels and INR — bleeding risk increases significantly; warfarin dose reduction and INR monitoring required

Metronidazole significantly inhibits CYP2C9 (the enzyme primarily responsible for S-warfarin metabolism), raising warfarin plasma levels and INR substantially. This combination requires enhanced INR monitoring and likely warfarin dose reduction.

Question 13: What is the role of benzocaine topical anaesthetic in dental practice?

Used for systemic analgesia
A type of vasoconstrictor added to LA cartridges
Provides dental pulp anaesthesia without injection
Used as a topical surface anaesthetic applied to mucosa before injection to reduce needle discomfort — works by superficial mucosal penetration only (Correct answer)

Correct answer: Used as a topical surface anaesthetic applied to mucosa before injection to reduce needle discomfort — works by superficial mucosal penetration only

Benzocaine (and lidocaine) gels/sprays are applied topically to dry oral mucosa before injection to anaesthetise the superficial nerve endings, reducing the discomfort of needle insertion.

Question 14: A patient is prescribed tetracycline for an oral infection. What dental concern must be discussed?

Only causes staining in adults
Tetracyclines cause permanent yellow-brown staining of developing teeth — contraindicated in pregnancy, breastfeeding, and children under 12 (Correct answer)
No dental concerns — tetracyclines are safe at all ages
Staining only occurs with prolonged use over 5 years

Correct answer: Tetracyclines cause permanent yellow-brown staining of developing teeth — contraindicated in pregnancy, breastfeeding, and children under 12

Tetracyclines chelate calcium in developing dental hard tissues, causing intrinsic yellow-brown staining and occasionally hypoplasia. They are absolutely contraindicated under 12 years, in pregnancy, and during breastfeeding.

Question 15: What is the 'dead man's handle' (deadman switch) concept in dental radiography?

A term for the exposure timer in intraoral radiography
The X-ray exposure switch must be actively held by the operator — releasing it automatically stops exposure, preventing accidental prolonged radiation release (Correct answer)
A safety device on the dental chair
A mechanism that powers down X-ray equipment when the dentist leaves the room

Correct answer: The X-ray exposure switch must be actively held by the operator — releasing it automatically stops exposure, preventing accidental prolonged radiation release

The deadman switch (non-latching exposure switch) ensures the operator must actively maintain pressure throughout exposure. Releasing the switch immediately terminates exposure, preventing accidental prolonged irradiation.

Question 16: The paralleling technique for periapical radiography requires a minimum focus-to-film distance of:

10 cm
40 cm
30 cm (Correct answer)
20 cm

Correct answer: 30 cm

The paralleling (long cone) technique requires a minimum focus-to-receptor distance of 30 cm (using a long cone/spacer) to produce near-parallel X-rays that minimise geometric distortion and magnification. Some systems use 40 cm for even better image geometry. The bisecting angle technique uses a shorter distance of 20 cm.

Question 17: What is a 'radicular cyst' (periapical cyst) and what stimulates its formation?

An inflammatory odontogenic cyst arising from the rests of Malassez, stimulated by inflammatory mediators from a non-vital infected tooth (Correct answer)
A cyst arising from salivary gland tissue
A traumatic cyst following tooth extraction
A developmental cyst around an unerupted tooth

Correct answer: An inflammatory odontogenic cyst arising from the rests of Malassez, stimulated by inflammatory mediators from a non-vital infected tooth

The radicular (periapical) cyst is the most common odontogenic cyst overall. It develops from epithelial rests of Malassez in the PDL, stimulated to proliferate by inflammatory mediators from pulp infection/necrosis.

Question 18: What is 'reactive oxygen species' involvement in periodontal disease?

Excessive ROS production by neutrophils during bacterial challenge damages host tissues (collagen, lipids, DNA), contributing to periodontal tissue destruction (Correct answer)
ROS are produced by periodontal bacteria to destroy host defences
ROS are beneficial antioxidants produced by the host
ROS only cause systemic disease, not periodontal destruction

Correct answer: Excessive ROS production by neutrophils during bacterial challenge damages host tissues (collagen, lipids, DNA), contributing to periodontal tissue destruction

In periodontal disease, sustained neutrophil activation produces excessive ROS beyond what is needed for bacterial killing. This oxidative stress damages host collagen, lipids, and DNA, contributing to bone and soft tissue destruction.

Question 19: What is the angle formed between the occlusal plane and the condylar guidance path called?

The Monson angle
The Frankfort angle
The Fischer angle (or Bennett angle — actually these differ; the angle between condylar path and occlusal plane is the Balkwill angle) (Correct answer)
The Bennett angle

Correct answer: The Fischer angle (or Bennett angle — actually these differ; the angle between condylar path and occlusal plane is the Balkwill angle)

The Balkwill angle (approximately 26°) is formed between the occlusal plane and the path of the condyle. The Bennett angle is the angle formed by the working side condyle moving laterally.

Question 20: Addison's disease is characterised by insufficiency of which endocrine gland?

Thyroid gland
Adrenal cortex (Correct answer)
Pituitary gland
Parathyroid gland

Correct answer: Adrenal cortex

Addison's disease (primary adrenal insufficiency) results from destruction of the adrenal cortex, leading to deficiency of cortisol and aldosterone. Dental relevance includes risk of adrenal crisis during stress and characteristic oral hyperpigmentation. Steroid supplementation may be needed before invasive dental procedures.

Question 21: What is centric relation (CR) in prosthodontic terms?

The relationship determined by muscle activity alone
The position of maximum tooth contact
The rest position of the mandible
The maxillomandibular relationship when the condyles are in their most superior and anterior position in the glenoid fossae, regardless of tooth contact (Correct answer)

Correct answer: The maxillomandibular relationship when the condyles are in their most superior and anterior position in the glenoid fossae, regardless of tooth contact

Centric relation (updated definition) is the position when the mandibular condyles are in their most superoanterior position against the posterior slope of the articular eminence, providing a reproducible reference for prosthodontic construction.

Question 22: Which property of commercially pure titanium (grade 4) makes it most suitable as a dental implant material?

Extremely low density reducing implant weight
Elastic modulus identical to cortical bone (17–20 GPa)
High thermal conductivity similar to dentine
Exceptional biocompatibility enabling osseointegration (Correct answer)

Correct answer: Exceptional biocompatibility enabling osseointegration

Titanium's native TiO2 surface oxide layer confers exceptional biocompatibility, enabling osseointegration — direct structural and functional contact between living bone and the implant surface without a fibrous tissue layer.

Question 23: A patient on warfarin with an INR of 3.2 presents for extraction of a single-rooted tooth. According to SDCEP guidance, what is the recommended approach?

Stop warfarin 3 days before extraction
Proceed with extraction using local haemostatic measures (Correct answer)
Convert to heparin bridging therapy
Postpone until INR is below 2.0

Correct answer: Proceed with extraction using local haemostatic measures

SDCEP guidance recommends that patients with a stable INR of 4.0 or below can have up to 3 simple extractions in general practice with local haemostatic measures (oxidised cellulose, sutures, tranexamic acid mouthwash). Warfarin should NOT be stopped as the thromboembolic risk outweighs the bleeding risk.

Question 24: What is the role of intraosseous anaesthesia (e.g., Stabident) in managing difficult-to-anaesthetise mandibular teeth?

Provides anaesthesia for the entire mandible from a single injection
Delivers anaesthetic directly into the medullary bone adjacent to the tooth, bypassing limitations of conventional blocks — effective supplement for irreversible pulpitis of lower molars where IDB is insufficient (Correct answer)
Replaces inferior dental block for all mandibular procedures
Used only for maxillary teeth

Correct answer: Delivers anaesthetic directly into the medullary bone adjacent to the tooth, bypassing limitations of conventional blocks — effective supplement for irreversible pulpitis of lower molars where IDB is insufficient

Intraosseous injection delivers LA directly into the cancellous bone adjacent to the tooth root apex, achieving local anaesthesia even when conventional IDB fails (common in irreversible pulpitis due to lowered inflammatory pH reducing LA efficacy).

Question 25: What is 'central sensitisation' and how does it contribute to chronic orofacial pain?

A peripheral nerve phenomenon only
A process that resolves automatically after acute pain resolves
Sensitisation caused only by opioid medications
Increased responsiveness of the central pain-processing neurons (in the trigeminal nucleus and higher centres) following prolonged nociceptive input — leads to amplified pain processing and expansion of pain areas (Correct answer)

Correct answer: Increased responsiveness of the central pain-processing neurons (in the trigeminal nucleus and higher centres) following prolonged nociceptive input — leads to amplified pain processing and expansion of pain areas

Central sensitisation (CS) develops when sustained nociceptive input causes 'wind-up' in the trigeminal nucleus and supraspinal centres, increasing synaptic efficacy. CS contributes to chronic orofacial pain by amplifying and expanding pain beyond the original site.

Question 26: What is the dental formula for the permanent human dentition?

I 1/1, C 1/1, P 2/2, M 3/3 = 30 teeth
I 2/2, C 1/1, P 2/2, M 2/2 = 28 teeth
I 2/2, C 1/1, P 2/2, M 3/3 = 32 teeth total (Correct answer)
I 2/2, C 2/2, P 2/2, M 3/3 = 36 teeth

Correct answer: I 2/2, C 1/1, P 2/2, M 3/3 = 32 teeth total

The permanent human dental formula is: 2 incisors, 1 canine, 2 premolars, 3 molars per quadrant, totalling 32 teeth (including third molars/wisdom teeth).

Question 27: A patient with uncontrolled hyperthyroidism is at risk of which dental emergency?

Hypoglycaemic episode
Adrenal crisis
Thyroid crisis (thyroid storm) (Correct answer)
Myxoedema coma

Correct answer: Thyroid crisis (thyroid storm)

Thyroid crisis (thyroid storm) is a life-threatening exacerbation of hyperthyroidism that can be precipitated by stress, infection, or surgery. Signs include extreme tachycardia, hyperthermia, agitation, and cardiovascular collapse. Dental treatment should be deferred until the patient's thyroid function is controlled.

Question 28: In the primary dentition, which tooth does NOT have a permanent successor?

Primary second molar (replaced by a permanent premolar) (Correct answer)
All primary teeth have permanent successors
Primary first molar
Primary canine

Correct answer: Primary second molar (replaced by a permanent premolar)

All primary teeth are replaced by permanent successors: primary incisors and canines by permanent incisors and canines; primary molars are replaced by premolars (not permanent molars).

Question 29: A patient with a known cardiac murmur is scheduled for dental extraction. According to current NICE guidelines, what is the recommended antibiotic prophylaxis regimen?

No routine antibiotic prophylaxis is recommended (Correct answer)
Azithromycin 500mg orally one hour before
Clindamycin 600mg orally one hour before
Amoxicillin 3g orally one hour before

Correct answer: No routine antibiotic prophylaxis is recommended

NICE Clinical Guideline CG64 (updated) states that antibiotic prophylaxis against infective endocarditis is NOT routinely recommended for dental procedures in the UK, regardless of the cardiac condition. This differs from American Heart Association guidelines and is a key point for the ORE examination.

Question 30: What is the significance of 'dark zones' in enamel caries histology?

Dark zones contain small pores filled with organic material and represent an area of remineralisation activity at the advancing front of early caries (Correct answer)
Dark zones are normal developmental features
Dark zones represent bacterial invasion of enamel
Dark zones are the most demineralised, active destruction areas

Correct answer: Dark zones contain small pores filled with organic material and represent an area of remineralisation activity at the advancing front of early caries

In the histology of early enamel caries, the dark zone (beneath the translucent zone at the lesion front) shows small pores with remineralisation activity — it is a zone of repair. This underpins the concept of treating early lesions by remineralisation.

Question 31: A 12-year-old child falls and avulses a permanent upper central incisor. The tooth has been dry for 45 minutes. What is the recommended reimplantation protocol?

Soak in sodium fluoride solution, remove necrotic PDL, then reimplant and accept need for later root canal treatment (Correct answer)
Do not reimplant as the prognosis is poor
Soak in Hank's balanced salt solution for 30 minutes then reimplant
Reimplant immediately without any preparation

Correct answer: Soak in sodium fluoride solution, remove necrotic PDL, then reimplant and accept need for later root canal treatment

When extra-alveolar dry time exceeds 60 minutes (or the PDL is clearly non-viable), the International Association of Dental Traumatology guidelines recommend removing the necrotic PDL, treating the root surface with fluoride, and reimplanting. Root canal treatment will be needed as revascularisation will not occur, but reimplantation preserves alveolar bone for later definitive treatment.

Question 32: A patient taking a selective serotonin reuptake inhibitor (SSRI) attends for dental treatment. Which drug interaction is most relevant in dentistry?

Increased risk of cardiac arrhythmia
Increased bleeding risk due to impaired platelet function (Correct answer)
Hypertensive crisis with adrenaline-containing LA
Reduced efficacy of local anaesthetic

Correct answer: Increased bleeding risk due to impaired platelet function

SSRIs inhibit serotonin reuptake into platelets, impairing platelet aggregation and increasing bleeding risk, particularly when combined with other antiplatelet agents or NSAIDs. Dentists should be aware of prolonged bleeding times and exercise caution during surgical procedures.

Question 33: A 45-year-old patient presents with a deep carious lesion on the mandibular first molar approaching the pulp. The tooth is vital with no spontaneous pain. What is the most appropriate treatment?

Direct composite restoration without pulp protection
Immediate root canal treatment
Extraction and implant placement
Indirect pulp capping with calcium hydroxide and restoration (Correct answer)

Correct answer: Indirect pulp capping with calcium hydroxide and restoration

Indirect pulp capping with calcium hydroxide is the treatment of choice for deep carious lesions in vital teeth without signs of irreversible pulpitis. This preserves pulp vitality by placing a biocompatible liner over the remaining thin dentine layer, promoting reparative dentine formation.

Question 34: What radiographic changes are seen in chronic periodontitis on horizontal bitewing radiographs?

Increased bone density around affected teeth
No radiographic changes — diagnosis is clinical only
Horizontal or vertical alveolar bone loss with the bone crest more than 2 mm apical to the CEJ, loss of lamina dura and calculus deposits (Correct answer)
Apical radiolucency only

Correct answer: Horizontal or vertical alveolar bone loss with the bone crest more than 2 mm apical to the CEJ, loss of lamina dura and calculus deposits

Bitewing radiographs in periodontitis show: horizontal bone loss (bone crest >2 mm below CEJ), angular/vertical defects in severe cases, loss of lamina dura continuity, calculus deposits, and furcation radiolucencies in severe posterior cases.

Question 35: What is the most common benign salivary gland tumour?

Adenoid cystic carcinoma
Mucoepidermoid carcinoma
Pleomorphic adenoma (Correct answer)
Warthin's tumour

Correct answer: Pleomorphic adenoma

Pleomorphic adenoma accounts for approximately 60–70% of all salivary gland tumours and is the most common benign tumour. It most frequently occurs in the parotid gland and presents as a slow-growing, painless, firm swelling. Treatment is surgical excision with adequate margin.

Question 36: At the molecular level, polymerisation shrinkage in composite resins occurs because:

Heat generated during curing causes thermal contraction of the polymer
Inorganic filler particles contract under high-intensity light exposure
Water sorption into the matrix displaces residual monomer causing collapse
Van der Waals intermolecular distances are replaced by shorter covalent bond lengths as monomers link (Correct answer)

Correct answer: Van der Waals intermolecular distances are replaced by shorter covalent bond lengths as monomers link

As free monomers (separated by Van der Waals gaps of ~3.5 Å) polymerise into a chain, covalent C-C bonds (~1.54 Å) replace the larger intermolecular distances, causing 1–5% volumetric shrinkage.

Question 37: A patient collapses in the dental chair and is unresponsive with no pulse. What is the correct compression-to-ventilation ratio for adult CPR?

15:2
30:2 (Correct answer)
15:1
30:1

Correct answer: 30:2

The Resuscitation Council (UK) guidelines recommend a compression-to-ventilation ratio of 30:2 for adult basic life support. Compressions should be performed at a rate of 100–120 per minute, at a depth of 5–6 cm, with minimal interruptions. An AED should be applied as soon as available.

Question 38: What is the significance of a raised serum alkaline phosphatase in dental/maxillofacial practice?

No significance in dental practice
May indicate Paget's disease of bone (elevated osteoblastic activity) affecting the jaws — causing bony expansion, altered tooth eruption, and extraction complications (Correct answer)
Always indicates liver disease
Always indicates hyperparathyroidism

Correct answer: May indicate Paget's disease of bone (elevated osteoblastic activity) affecting the jaws — causing bony expansion, altered tooth eruption, and extraction complications

Elevated alkaline phosphatase in the context of bony jaw expansion, cotton-wool radiographic appearance, and altered teeth suggests Paget's disease of bone. Affected bone has increased vascularity, making extractions high-risk for haemorrhage.

Question 39: The fluoride release profile of conventional glass ionomer cement (GIC) is best described as:

Progressively increasing fluoride release as the cement fully matures
No fluoride release until the cement is mechanically stressed or cracked
Initial high burst release followed by sustained lower-level long-term release (Correct answer)
Constant steady-state release throughout its entire lifespan

Correct answer: Initial high burst release followed by sustained lower-level long-term release

GIC shows an initial high burst of fluoride release in the first 24–48 hours, followed by sustained lower-level release; it also acts as a fluoride reservoir that can be recharged by topical fluoride application.

Question 40: A patient is prescribed metronidazole 400 mg TDS for a periodontal condition. What is the recommended duration?

14 days for all dental infections
28 days
Until symptoms resolve without a defined end date
7 days (or up to 7 days maximum for acute infections) (Correct answer)

Correct answer: 7 days (or up to 7 days maximum for acute infections)

Metronidazole for acute dental/periodontal infections is prescribed for 7 days (400 mg TDS in adults). Shorter courses (3–5 days) may be used for specific indications. Prolonged courses are not recommended due to resistance risk.

Question 41: What is the primary mineral component of dental enamel?

Tricalcium phosphate
Calcium carbonate
Fluorapatite
Hydroxyapatite (Correct answer)

Correct answer: Hydroxyapatite

Dental enamel is composed of approximately 96% inorganic material by weight, primarily in the form of hydroxyapatite crystals (Ca10(PO4)6(OH)2). These crystals are organised into enamel rods, making enamel the hardest biological tissue in the human body.

Question 42: Which radiographic technique is most appropriate for detecting proximal caries in posterior teeth?

Lateral cephalogram
Dental panoramic tomograph
Periapical radiograph with paralleling technique
Horizontal bitewing radiograph (Correct answer)

Correct answer: Horizontal bitewing radiograph

Horizontal bitewing radiographs are the gold standard for detecting proximal (interproximal) caries in posterior teeth. They show the crowns of upper and lower teeth and the crestal bone level with minimal geometric distortion, making early enamel lesions visible that cannot be detected clinically.

Question 43: What is the 'working side' in lateral excursion of the mandible?

The side where the condyle makes a Bennett movement
The side towards which the mandible moves during lateral jaw movement (Correct answer)
The side where the condyle moves straight
The non-chewing side

Correct answer: The side towards which the mandible moves during lateral jaw movement

The working side (chewing side) is the side towards which the mandible moves in lateral excursion. The working-side condyle pivots and rotates; the balancing-side condyle makes a translatory Bennett movement.

Question 44: What is the clinical significance of 'Ramsay Hunt syndrome' in dental practice?

A salivary gland condition causing xerostomia
Varicella-zoster virus reactivation in the geniculate ganglion causing unilateral facial palsy, ear pain, and vesicles in the ear canal and soft palate — requiring antiviral treatment and dental/neurological awareness (Correct answer)
A TMJ condition causing pain
Trigeminal neuralgia secondary to herpes

Correct answer: Varicella-zoster virus reactivation in the geniculate ganglion causing unilateral facial palsy, ear pain, and vesicles in the ear canal and soft palate — requiring antiviral treatment and dental/neurological awareness

Ramsay Hunt syndrome (herpes zoster oticus) involves VZV reactivation in CN VII (geniculate ganglion), causing lower motor neuron facial palsy, severe ear pain (otalgia), and vesicles in the EAC and soft palate. Urgent antiviral therapy is needed.

Question 45: What is the correct dose of intramuscular adrenaline for an adult experiencing anaphylaxis in a dental surgery?

1ml of 1:10,000 (0.1mg)
0.5ml of 1:1000 (0.5mg) (Correct answer)
0.1ml of 1:1000 (0.1mg)
1ml of 1:1000 (1mg)

Correct answer: 0.5ml of 1:1000 (0.5mg)

The Resuscitation Council (UK) guidelines recommend 0.5ml of 1:1000 adrenaline (500 micrograms) given intramuscularly into the anterolateral thigh for adult anaphylaxis. This can be repeated every 5 minutes if there is no improvement. Intravenous adrenaline should only be given by experienced specialists.

Question 46: What is the rationale for prescribing dexamethasone before lower third molar surgery?

Prophylactic corticosteroid reduces post-operative trismus, swelling, and pain by suppressing inflammatory mediators before surgical trauma occurs (Correct answer)
To treat infection preoperatively
To reduce anaesthetic requirements
To prevent dry socket

Correct answer: Prophylactic corticosteroid reduces post-operative trismus, swelling, and pain by suppressing inflammatory mediators before surgical trauma occurs

Pre-operative dexamethasone (4–8 mg IM or IV) reduces post-surgical trismus, facial swelling, and pain by pre-emptively suppressing the inflammatory cascade. It is used in third molar surgery and other oral surgical procedures.

Question 47: Which investigation is most appropriate for assessing the relationship between an impacted lower third molar and the inferior alveolar canal?

Upper standard occlusal radiograph
Periapical radiograph
Cone beam computed tomography (CBCT) (Correct answer)
Lateral cephalogram

Correct answer: Cone beam computed tomography (CBCT)

CBCT provides three-dimensional imaging that accurately demonstrates the spatial relationship between the impacted tooth roots and the inferior alveolar canal. NICE guidelines recommend CBCT when conventional radiographs show signs of a close relationship, such as darkening of roots or interruption of the canal outline.

Question 48: During elevation of a lower third molar root, the root tip is displaced lingually. What is the immediate best course of action?

Raise a lingual flap and retrieve under direct vision
Leave it and inform the patient
Attempt retrieval with a Mitchell's trimmer through the socket
Take a radiograph, note the location, and refer to a specialist oral surgeon (Correct answer)

Correct answer: Take a radiograph, note the location, and refer to a specialist oral surgeon

A displaced root fragment in the lingual tissues should not be pursued through the socket or by raising a lingual flap in a general practice setting, as this risks lingual nerve damage and displacement into deeper tissue spaces. The correct approach is to document the event radiographically and refer to a specialist.

Question 49: How many cusps does a maxillary first molar typically have?

6 cusps
5 cusps always
3 cusps
4 cusps (with a 5th Cusp of Carabelli occasionally) (Correct answer)

Correct answer: 4 cusps (with a 5th Cusp of Carabelli occasionally)

The maxillary first molar has 4 main cusps: mesiobuccal, distobuccal, mesiopalatal (largest), and distopalatal. The Cusp of Carabelli is an accessory cusp on the mesiopalatal cusp, present in about 60% of individuals.

Question 50: A diabetic patient becomes sweaty, confused, and tremulous during a dental appointment. What is the most appropriate immediate management?

Administer intramuscular adrenaline
Administer sublingual GTN
Place patient supine and wait
Give oral glucose gel or a sugary drink if conscious (Correct answer)

Correct answer: Give oral glucose gel or a sugary drink if conscious

These are signs of hypoglycaemia. If the patient is conscious and can swallow, the immediate treatment is oral glucose (glucose gel, tablets, or a sugary drink such as orange juice). If unconscious, intramuscular glucagon 1mg should be administered. This is a core medical emergency scenario for the GDC.

Question 51: What is 'preventive analgesia' and why is it used in oral surgery?

Topical anaesthesia as the only analgesic strategy
A technique to prevent opioid prescribing entirely
Administering analgesics before painful stimuli occur (pre-operative) to reduce central sensitisation and post-operative pain intensity — e.g., ibuprofen + paracetamol 1 hour before third molar surgery (Correct answer)
Analgesics given only after the patient reports pain

Correct answer: Administering analgesics before painful stimuli occur (pre-operative) to reduce central sensitisation and post-operative pain intensity — e.g., ibuprofen + paracetamol 1 hour before third molar surgery

Pre-emptive/preventive analgesia (e.g., oral ibuprofen and paracetamol before surgery) reduces central sensitisation and wind-up in the trigeminal pathways. Evidence supports reduced post-operative pain intensity with pre-operative analgesic administration.

Question 52: What is the mechanism of action of non-steroidal anti-inflammatory drugs (NSAIDs) in dentistry?

Block opioid receptors
Reduce bacterial infection
Stimulate endogenous endorphin release
Inhibit cyclo-oxygenase (COX) enzymes, reducing prostaglandin synthesis, decreasing pain, inflammation, and fever (Correct answer)

Correct answer: Inhibit cyclo-oxygenase (COX) enzymes, reducing prostaglandin synthesis, decreasing pain, inflammation, and fever

NSAIDs (ibuprofen, diclofenac) inhibit COX-1 and COX-2, reducing prostaglandin synthesis at sites of inflammation. This reduces sensitisation of peripheral nociceptors, providing analgesic and anti-inflammatory effects.

Question 53: What is the recommended minimum distance the operator should stand from the X-ray tube head during exposure?

0.5 metres is sufficient
At least 1.5–2 metres away, outside the primary beam, ideally behind a lead screen or wall (Correct answer)
No minimum distance if wearing a lead apron
Distance only matters for panoramic equipment

Correct answer: At least 1.5–2 metres away, outside the primary beam, ideally behind a lead screen or wall

Operators should stand at least 1.5–2 metres from the tube head, outside the primary beam (not at 90° to it), and ideally behind a structural barrier during dental X-ray exposures.

Question 54: What is the formula for the primary dentition and how many primary teeth are there?

I 2/2, C 1/1, M 2/2 = 20 teeth total (Correct answer)
I 2/2, C 1/1, P 1/1, M 2/2 = 24 teeth
I 1/1, C 1/1, M 2/2 = 16 teeth
I 2/2, C 1/1, M 3/3 = 24 teeth

Correct answer: I 2/2, C 1/1, M 2/2 = 20 teeth total

The primary dentition has 20 teeth: 2 central incisors, 2 lateral incisors, 2 canines, 2 first molars, and 2 second molars per arch (10 upper, 10 lower). There are no premolars in the primary dentition.

Question 55: What is the specific indication for using IV paracetamol (Perfalgan) in dental/oral surgical settings?

For routine dental procedures in conscious patients
As a loading dose before oral paracetamol is started at home
When oral route is unavailable or rapid onset analgesia is needed peri- or post-operatively under general anaesthesia — achieves therapeutic levels in 15 minutes (Correct answer)
Only for patients allergic to ibuprofen

Correct answer: When oral route is unavailable or rapid onset analgesia is needed peri- or post-operatively under general anaesthesia — achieves therapeutic levels in 15 minutes

IV paracetamol (Perfalgan) is used in hospital oral surgical settings when patients cannot take oral medication (post-GA) or rapid onset is needed. IV route achieves peak concentrations faster than oral, providing prompt perioperative analgesia.

Question 56: What is 'denture stomatitis' and what is its most common cause?

A viral infection specific to denture wearers
An allergic reaction to denture acrylic
Erythematous mucositis under a denture, most commonly caused by Candida albicans overgrowth facilitated by continuous denture wear and poor denture hygiene (Correct answer)
A bacterial infection under dentures

Correct answer: Erythematous mucositis under a denture, most commonly caused by Candida albicans overgrowth facilitated by continuous denture wear and poor denture hygiene

Denture stomatitis (Newton type I–III) is erythema under an upper denture, predominantly caused by Candida albicans overgrowth. Risk factors include continuous wear, poor denture hygiene, and dry mouth.

Question 57: A patient taking metronidazole for a dental infection should be warned about interaction with which substance?

Caffeine
Dairy products
Grapefruit juice
Alcohol (Correct answer)

Correct answer: Alcohol

Metronidazole inhibits aldehyde dehydrogenase, causing a disulfiram-like reaction when alcohol is consumed. Patients experience nausea, vomiting, flushing, and tachycardia. Patients should be advised to avoid alcohol during treatment and for 48 hours after completing the course.

Question 58: What is the histological difference between an epithelial lined and non-epithelial-lined jaw cyst?

Non-epithelial cysts cannot occur in the jaws
Odontogenic cysts (e.g., radicular, dentigerous) are lined by epithelium derived from tooth-forming tissues; traumatic (simple bone) cysts have no epithelial lining (Correct answer)
All jaw cysts are epithelial-lined by definition
The difference is only relevant for malignant transformation risk

Correct answer: Odontogenic cysts (e.g., radicular, dentigerous) are lined by epithelium derived from tooth-forming tissues; traumatic (simple bone) cysts have no epithelial lining

True jaw cysts (radicular, dentigerous, OKC) are lined by epithelium. The simple (traumatic) bone cyst is a pseudocyst — an empty cavity within bone with no epithelial lining, probably representing an intraosseous haematoma.

Question 59: What is 'pericoronitis' and which tooth is most commonly affected?

Gingival inflammation around all erupting teeth
Inflammation around the apex of any tooth
Inflammation of the soft tissue operculum overlying an incompletely erupted tooth — most commonly the mandibular third molar (wisdom tooth) (Correct answer)
An abscess within the dental pulp

Correct answer: Inflammation of the soft tissue operculum overlying an incompletely erupted tooth — most commonly the mandibular third molar (wisdom tooth)

Pericoronitis is acute or chronic inflammation of the pericoronal flap (operculum) covering an incompletely erupted tooth. It is most commonly associated with the lower third molar, often complicated by bacterial colonisation under the flap.

Question 60: What is the oral manifestation of Stevens-Johnson syndrome relevant to dentistry?

Minor aphthous-type ulcers only
Candidal infection
Gingival fibromatosis
Severe mucositis with haemorrhagic crusting of lips, widespread oral ulceration, and target lesions on skin — potentially triggered by drugs (e.g., carbamazepine, allopurinol) or infections (Correct answer)

Correct answer: Severe mucositis with haemorrhagic crusting of lips, widespread oral ulceration, and target lesions on skin — potentially triggered by drugs (e.g., carbamazepine, allopurinol) or infections

Stevens-Johnson syndrome (severe form of erythema multiforme) presents with extensive haemorrhagic lip crusting, painful widespread oral ulceration, and skin/ocular involvement. Drug triggers include AEDs, antibiotics, and allopurinol.

Question 61: What is 'freeway space' (interocclusal distance)?

The space between maxillary and mandibular teeth when the mandible is in the rest position, typically 2–4 mm (Correct answer)
The distance between the condyle and glenoid fossa
The space created by a missing tooth
The gap between adjacent teeth

Correct answer: The space between maxillary and mandibular teeth when the mandible is in the rest position, typically 2–4 mm

Freeway space (interocclusal clearance) is the vertical distance between the upper and lower teeth when the mandible is in rest position. It equals the difference between rest vertical dimension and occlusal vertical dimension.

Question 62: Which cranial nerve is responsible for the motor supply to the muscles of mastication?

Trigeminal nerve (V) — mandibular division (Correct answer)
Facial nerve (VII)
Hypoglossal nerve (XII)
Glossopharyngeal nerve (IX)

Correct answer: Trigeminal nerve (V) — mandibular division

The mandibular division (V3) of the trigeminal nerve provides motor innervation to the muscles of mastication (masseter, temporalis, medial and lateral pterygoids) as well as mylohyoid, anterior belly of digastric, tensor veli palatini, and tensor tympani.

Question 63: Which of the following is an absolute contraindication to dental extraction without specialist referral?

Patients receiving intravenous bisphosphonate therapy for bone metastases (Correct answer)
Well-controlled type 2 diabetes
Patients on low-dose aspirin
History of mild penicillin allergy

Correct answer: Patients receiving intravenous bisphosphonate therapy for bone metastases

Patients on intravenous bisphosphonates (e.g., zoledronic acid for bone metastases) have a significantly elevated risk of MRONJ compared to oral bisphosphonate users. These patients should be referred to a specialist oral surgery unit for extraction with appropriate planning and follow-up.

Question 64: What is the pharmacological management of post-herpetic neuralgia (PHN) affecting the trigeminal nerve?

Amitriptyline (TCA), gabapentin/pregabalin (calcium channel modulators), lidocaine patches, or capsaicin cream — NICE-recommended neuropathic pain treatments (Correct answer)
Penicillin antibiotic therapy
NSAIDs as first-line
Surgical decompression as first-line

Correct answer: Amitriptyline (TCA), gabapentin/pregabalin (calcium channel modulators), lidocaine patches, or capsaicin cream — NICE-recommended neuropathic pain treatments

PHN (persisting pain after herpes zoster/shingles) affecting the trigeminal distribution is managed with NICE-recommended neuropathic pain agents: amitriptyline, gabapentin or pregabalin, topical lidocaine, or capsaicin 8% patch.

Question 65: A patient presents with multiple oral ulcers, genital ulcers and ocular inflammation. Which condition should be suspected?

Pemphigus vulgaris
Crohn's disease
Systemic lupus erythematosus
Behçet's disease (Correct answer)

Correct answer: Behçet's disease

The triad of recurrent oral ulcers, genital ulcers and uveitis (ocular inflammation) is the classic presentation of Behçet's disease. It is a systemic vasculitis more common in populations along the ancient Silk Road and requires multidisciplinary management.

Question 66: What is 'acute pulpitis' pain and how does it differ from 'irreversible pulpitis'?

Reversible pulpitis: short, sharp pain triggered by stimuli (cold) that resolves quickly; Irreversible: spontaneous, lingering, severe pain not fully resolving after stimulus removal — indicates pulp cannot recover (Correct answer)
Irreversible pulpitis always has visible clinical swelling
Reversible pulpitis is always associated with visible caries
There is no clinical distinction between the two

Correct answer: Reversible pulpitis: short, sharp pain triggered by stimuli (cold) that resolves quickly; Irreversible: spontaneous, lingering, severe pain not fully resolving after stimulus removal — indicates pulp cannot recover

Reversible pulpitis: brief, stimulus-induced pain resolving within seconds — pulp can recover. Irreversible pulpitis: spontaneous pain and/or lingering pain after stimulus removal (>30 seconds) — irreversible inflammation requiring pulp extirpation or extraction.

Question 67: What is the significance of 'lamina dura' in periapical radiographs?

A normal finding only in children
The border of a cystic lesion
A calcified ligament visible only on bitewing radiographs
A white line on the radiograph representing the dense cortical bone lining the tooth socket — loss of lamina dura indicates periapical pathology or periodontitis (Correct answer)

Correct answer: A white line on the radiograph representing the dense cortical bone lining the tooth socket — loss of lamina dura indicates periapical pathology or periodontitis

The lamina dura (radiographic white line) represents the dense cortical bone (alveolar bone proper) lining the tooth socket. Its loss in the periapical region indicates periapical pathology; loss in the crestal region suggests periodontitis.

Question 68: Which cells are responsible for dentine formation?

Osteoblasts
Ameloblasts
Cementoblasts
Odontoblasts (Correct answer)

Correct answer: Odontoblasts

Odontoblasts are the dentine-forming cells derived from neural crest cells. They line the pulp chamber and extend processes into dentinal tubules (Tomes' fibres), producing predentine which mineralises to become dentine.

Question 69: What is 'referred pain' in dentistry and give an example?

Pain perceived at a location distant from the actual source — e.g., mandibular molar pain referred to the ear, or maxillary sinus pain felt in upper posterior teeth (Correct answer)
Pain that involves two adjacent teeth simultaneously
Pain that is intermittent rather than continuous
Pain that travels along the nerve after injection

Correct answer: Pain perceived at a location distant from the actual source — e.g., mandibular molar pain referred to the ear, or maxillary sinus pain felt in upper posterior teeth

Referred pain in dentistry occurs because convergence of sensory inputs causes mislocalization. Classic examples: lower molar pain referred to the ear or temple; upper premolar/molar pain referred to/from the maxillary sinus.

Question 70: What is the 'gate control theory' of pain and how does it explain pain relief from transcutaneous electrical nerve stimulation (TENS)?

Large diameter A-beta fibres (non-painful sensory) can inhibit nociceptive transmission at the spinal cord 'gate' — TENS activates A-beta fibres, closing the gate and reducing pain signals to the brain (Correct answer)
The gate theory is now considered completely obsolete
TENS acts by releasing opioids only, not gate control
Gate control only applies to spinal cord injuries

Correct answer: Large diameter A-beta fibres (non-painful sensory) can inhibit nociceptive transmission at the spinal cord 'gate' — TENS activates A-beta fibres, closing the gate and reducing pain signals to the brain

Melzack and Wall's gate control theory proposes that non-painful sensory input via A-beta fibres can inhibit nociceptive transmission in the dorsal horn. TENS uses this mechanism by activating tactile A-beta fibres, reducing pain signal transmission.

Question 71: What is 'Hutchinson's triad' and what condition does it indicate?

Hutchinson's incisors (notched), interstitial keratitis, and nerve deafness — signs of congenital syphilis (Correct answer)
Signs of ectodermal dysplasia
Features of cretinism
A triad of TMJ symptoms

Correct answer: Hutchinson's incisors (notched), interstitial keratitis, and nerve deafness — signs of congenital syphilis

Hutchinson's triad is pathognomonic of congenital syphilis: Hutchinson's incisors (barrel-shaped, notched), interstitial keratitis (corneal inflammation), and 8th nerve deafness (hearing loss).

Question 72: What is the role of salivary immunoglobulin A (IgA) in oral defence?

Forms antibody-antigen complexes that trigger inflammation
Acts as an opsonin for phagocytosis
Neutralises bacterial endotoxins in the bloodstream
Provides mucosal immunity by binding antigens and preventing bacterial adherence to oral surfaces without invoking complement (Correct answer)

Correct answer: Provides mucosal immunity by binding antigens and preventing bacterial adherence to oral surfaces without invoking complement

Secretory IgA (sIgA) is the predominant antibody in saliva. It agglutinates bacteria and blocks their adhesion to mucosal surfaces, providing non-inflammatory first-line immune defence without complement activation.

Question 73: What is 'centric occlusion' (maximum intercuspation, MIP)?

The mandibular position of maximum tooth contact regardless of condylar position (Correct answer)
The rest position of the mandible
The position during chewing when vertical pressure is maximum
The position of the mandible when the condyles are in centric relation

Correct answer: The mandibular position of maximum tooth contact regardless of condylar position

Centric occlusion (now termed Maximum Intercuspal Position — MIP) is the occlusal position where maximum tooth contact occurs. It may or may not coincide with centric relation (condyles in terminal hinge position).

Question 74: What is the primary setting reaction of addition silicone (PVS) impression material?

Polycondensation releasing ethanol as a volatile by-product
Platinum-catalysed hydrosilylation of Si-H groups across vinyl groups (Correct answer)
Acid-base neutralisation between base and catalyst pastes
Radical chain-growth polymerisation initiated by benzoyl peroxide

Correct answer: Platinum-catalysed hydrosilylation of Si-H groups across vinyl groups

Addition silicones set via a platinum-catalysed hydrosilylation reaction in which Si-H groups add across vinyl (Si-CH=CH2) groups with no by-product released, giving excellent accuracy and dimensional stability.

Question 75: What is the normal resting blood pressure range for a healthy adult according to NICE hypertension guidelines?

Below 130/85 mmHg
Below 120/80 mmHg
Below 140/90 mmHg (Correct answer)
Below 150/90 mmHg

Correct answer: Below 140/90 mmHg

NICE guidelines define hypertension as a clinic blood pressure persistently at or above 140/90 mmHg (with ambulatory or home monitoring confirmation at 135/85 mmHg). Below 140/90 is considered the normal range in clinical practice, though lower targets may apply for certain patient groups.

Question 76: Which fascial space infection carries the highest risk of airway compromise?

Infraorbital space
Buccal space
Ludwig's angina (bilateral submandibular space) (Correct answer)
Canine space

Correct answer: Ludwig's angina (bilateral submandibular space)

Ludwig's angina involves bilateral infection of the submandibular, sublingual, and submental spaces, causing rapid swelling of the floor of the mouth and tongue elevation. This can lead to fatal airway obstruction and is a surgical emergency requiring immediate hospital admission, IV antibiotics, and potentially surgical decompression or tracheostomy.

Question 77: The mesiolingual cusp of the maxillary first molar is sometimes called the 'cusp of':

Wilson
Nance (sometimes referred to as the dominant palatal cusp, related to Nance contact point) — though the Cusp of Carabelli is the additional cusp (Correct answer)
Spee
Carabelli — but this is the 5th accessory cusp; the mesiolingual is simply the largest cusp

Correct answer: Nance (sometimes referred to as the dominant palatal cusp, related to Nance contact point) — though the Cusp of Carabelli is the additional cusp

The mesiolingual cusp of the maxillary first molar is the largest cusp and is sometimes referred to in orthodontic literature as 'Nance's cusp'. The Cusp of Carabelli is a separate 5th accessory cusp on the mesiopalatal cusp.

Question 78: What is the 'angle of the mandible' and why is it clinically significant in dentistry?

The incisal angle of the lower incisors
The angulation of the mental foramen
The angle formed between the mandibular plane and the Frankfort horizontal
The gonial angle — at the junction of the posterior border of the ramus and the lower border of the body; relates to growth pattern and impacts orthognathic assessment (Correct answer)

Correct answer: The gonial angle — at the junction of the posterior border of the ramus and the lower border of the body; relates to growth pattern and impacts orthognathic assessment

The gonial angle (angle of mandible) is typically 100–130°. A high gonial angle indicates a vertical growth pattern; a low angle indicates horizontal growth. This impacts treatment planning in orthodontics and orthognathic surgery.

Question 79: What is the role of the 'referral criteria' in dental radiography?

Identifying which patients need dental implants
Evidence-based guidelines (e.g., FGDP Selection Criteria for Dental Radiography) that ensure X-rays are only taken when clinical benefit justifies the radiation risk — not as routine (Correct answer)
Selecting the exposure time for different patients
Determining the type of film to use

Correct answer: Evidence-based guidelines (e.g., FGDP Selection Criteria for Dental Radiography) that ensure X-rays are only taken when clinical benefit justifies the radiation risk — not as routine

Referral criteria (selection criteria) ensure radiographs are only prescribed when clinical information gained will positively influence patient management. Routine radiographs without clinical justification are unjustified exposures.

Question 80: Which coagulation pathway is assessed by the prothrombin time (PT) and INR?

Common pathway only
Extrinsic pathway (Correct answer)
Fibrinolytic pathway
Intrinsic pathway

Correct answer: Extrinsic pathway

The PT/INR assesses the extrinsic and common coagulation pathways (factors VII, X, V, II, and fibrinogen). It is the standard monitoring test for warfarin therapy. The APTT, by contrast, assesses the intrinsic pathway and is used to monitor heparin therapy.

Question 81: Which type of dentine is formed as a physiological response throughout life?

Mantle dentine
Tertiary (reparative) dentine
Primary dentine
Secondary dentine (Correct answer)

Correct answer: Secondary dentine

Secondary dentine is deposited slowly and continuously by odontoblasts throughout the life of a vital tooth, after root formation is complete. This gradually reduces the size of the pulp chamber. Tertiary dentine, by contrast, is formed as a pathological response to stimuli such as caries or attrition.

Question 82: How many roots does the maxillary first premolar typically have?

Two roots (buccal and palatal) — one of the few two-rooted premolars (Correct answer)
Three roots
One root only
One root with two canals always

Correct answer: Two roots (buccal and palatal) — one of the few two-rooted premolars

The maxillary first premolar typically has two roots (buccal and palatal), making it anatomically distinct from the maxillary second premolar which more commonly has one root. Root canals correspond to each root.

Question 83: What is the average root length of the maxillary central incisor?

8 mm
Approximately 13 mm (Correct answer)
5 mm
20 mm

Correct answer: Approximately 13 mm

The maxillary central incisor has a crown length of approximately 10–11 mm and a root length of approximately 13 mm, giving a total tooth length of approximately 23 mm on average.

Question 84: What is the significance of prescribing erythromycin with a patient taking warfarin?

Only relevant if erythromycin is given intravenously
Erythromycin inhibits CYP3A4 causing increased warfarin levels, raising INR and bleeding risk — requires INR monitoring and possible warfarin dose reduction (Correct answer)
Erythromycin reduces warfarin absorption only
No interaction — safe to prescribe together

Correct answer: Erythromycin inhibits CYP3A4 causing increased warfarin levels, raising INR and bleeding risk — requires INR monitoring and possible warfarin dose reduction

Erythromycin is a moderate CYP3A4 and CYP1A2 inhibitor, reducing warfarin metabolism and elevating INR. Clinically significant bleeding risk increase means enhanced INR monitoring is required when these drugs are co-prescribed.

Question 85: Which type of white blood cell is most increased in a bacterial infection?

Lymphocytes
Eosinophils
Basophils
Neutrophils (Correct answer)

Correct answer: Neutrophils

Neutrophils are the primary phagocytic cells of the innate immune system and are the first responders to bacterial infection. A raised neutrophil count (neutrophilia) on a full blood count is a hallmark of acute bacterial infection. Lymphocytosis, in contrast, is more associated with viral infections.

Question 86: What is the pathogenesis of periapical abscess formation?

An allergic reaction to pulp bacteria
Viral infection of the periapical tissues
Direct bacterial spread from the gingival pocket
Bacterial products from pulp necrosis spread beyond the apex, triggering acute inflammation with neutrophil accumulation and pus formation in the periapical tissues (Correct answer)

Correct answer: Bacterial products from pulp necrosis spread beyond the apex, triggering acute inflammation with neutrophil accumulation and pus formation in the periapical tissues

Pulp necrosis from caries/trauma allows bacteria to colonise the root canal. Bacteria and their products exit the apex, stimulating acute inflammatory infiltrate (mainly neutrophils), resulting in pus accumulation (abscess) in periapical bone or soft tissue.

Question 87: The dental papilla gives rise to which structure of the developed tooth?

Periodontal ligament
Cementum
Dentine and pulp (Correct answer)
Enamel

Correct answer: Dentine and pulp

The dental papilla is the ectomesenchymal condensation that forms the core of the developing tooth germ. It differentiates into odontoblasts (which form dentine) and the dental pulp. The dental follicle, in contrast, gives rise to cementum, periodontal ligament, and alveolar bone.

Question 88: A patient presents 3 days post-extraction with severe throbbing pain, a foul taste, and an empty socket with exposed bone. What is the diagnosis?

Residual root fracture
Normal post-extraction healing
Alveolar osteitis (dry socket) (Correct answer)
Osteomyelitis

Correct answer: Alveolar osteitis (dry socket)

Alveolar osteitis (dry socket) typically presents 2–5 days after extraction with severe pain, halitosis, and an empty socket where the blood clot has been lost or lysed. Risk factors include smoking, oral contraceptive use, and traumatic extraction. Management involves irrigation and placement of an obtundent dressing.

Question 89: Which ADA/ISO type of gypsum product has the highest compressive strength?

Type III — dental stone
Type IV — die stone (improved stone)
Type II — dental plaster
Type V — high-strength, high-expansion stone (Correct answer)

Correct answer: Type V — high-strength, high-expansion stone

Type V gypsum (high-strength, high-expansion die stone) has the highest compressive strength of all gypsum types, exceeding 35 MPa, making it suitable for precision die work.

Question 90: What is the oral surgical management of trigeminal neuralgia when pharmacological treatment fails?

Tooth extraction of all teeth in the affected distribution
Dental splint therapy
Microvascular decompression (MVD), Gamma Knife radiosurgery, percutaneous rhizotomy (glycerol/balloon/radiofrequency) — specialist neurosurgical referral required (Correct answer)
Coronectomy of lower third molars

Correct answer: Microvascular decompression (MVD), Gamma Knife radiosurgery, percutaneous rhizotomy (glycerol/balloon/radiofrequency) — specialist neurosurgical referral required

When carbamazepine/pharmacotherapy fails, surgical options for TN include: MVD (decompresses the trigeminal root from a vascular loop — most durable), Gamma Knife stereotactic radiosurgery (non-invasive), and percutaneous rhizotomy procedures. All require specialist neurosurgical referral.

Question 91: What is the 'tubercle of Zuckerkandl' (Carabelli cusp) and where is it found?

An accessory cusp on the mesiopalatal cusp of the maxillary first molar (Correct answer)
An accessory root on lower canines
A root anomaly on the lower premolar
A developmental pit on the upper central incisor

Correct answer: An accessory cusp on the mesiopalatal cusp of the maxillary first molar

The Cusp of Carabelli is a 5th (accessory) cusp found on the mesiopalatal surface of the maxillary first molar (occasionally second molar). It is more common in people of European descent.

Question 92: During surgical extraction of a lower third molar, the lingual nerve is most at risk at which anatomical location?

At the level of the sigmoid notch
At the mental foramen
At the lingual plate of the third molar region, just below the alveolar crest (Correct answer)
At the lingula of the mandible

Correct answer: At the lingual plate of the third molar region, just below the alveolar crest

The lingual nerve runs in close proximity to the lingual plate in the third molar region, often lying at or just below the level of the alveolar crest. Studies have shown it is directly on the bone surface in approximately 15% of cases, making it vulnerable during flap elevation and bone removal.

Question 93: What does the ALARP principle stand for in dental radiography?

As Low As Reasonably Practicable (Correct answer)
Assessed Levels Are Routinely Plotted
Always Limit All Radiation Procedures
As Long As Reasonably Practicable

Correct answer: As Low As Reasonably Practicable

ALARP stands for As Low As Reasonably Practicable. It is the UK regulatory principle requiring that radiation doses be kept as low as is reasonably practicable while still obtaining diagnostically adequate images. This includes using rectangular collimation, correct exposure settings, and digital sensors where possible.

Question 94: What is 'allodynia' and when does it occur in dental/orofacial pain?

Pain only occurring at night
Normal pain from a stimulus that always causes pain
Pain from a stimulus that does not normally cause pain (e.g., light touch, air, cold water causing pain in irreversible pulpitis) — indicates sensitisation of the pain pathway (Correct answer)
Pain radiating to distant sites

Correct answer: Pain from a stimulus that does not normally cause pain (e.g., light touch, air, cold water causing pain in irreversible pulpitis) — indicates sensitisation of the pain pathway

Allodynia is pain elicited by normally non-painful stimuli (e.g., touch, temperature, air). It indicates sensitisation of the pain pathway (peripheral or central). In irreversible pulpitis, allodynia explains pain from non-noxious stimuli like cool water.

Question 95: Which hepatitis virus is most commonly transmitted through needlestick injuries in the dental setting?

Hepatitis A
Hepatitis C
Hepatitis D
Hepatitis B (Correct answer)

Correct answer: Hepatitis B

Hepatitis B has the highest transmission rate via needlestick injury (approximately 30% from an infected source), compared to hepatitis C (approximately 3%) and HIV (approximately 0.3%). This is why hepatitis B vaccination is mandatory for all dental healthcare workers in the UK.

Question 96: Which of the following is the most appropriate initial management for a patient presenting with acute necrotising ulcerative gingivitis (ANUG)?

Metronidazole 400mg three times daily for 3 days and gentle debridement (Correct answer)
Referral for biopsy
Chlorhexidine mouthwash alone
Scaling and root planing under local anaesthetic

Correct answer: Metronidazole 400mg three times daily for 3 days and gentle debridement

ANUG is managed initially with metronidazole (the antimicrobial of choice targeting the anaerobic fusiform and spirochaete bacteria), gentle superficial debridement, and oral hygiene instruction. Aggressive scaling should be avoided in the acute phase due to pain and risk of bacteraemia.

Question 97: Which permanent tooth has the longest root in the human dentition?

Upper central incisor
Lower first molar
Upper first premolar
Upper canine (Correct answer)

Correct answer: Upper canine

The maxillary canine has the longest root of any tooth in the human dentition. Its long, robust root provides excellent anchorage, which is why canines are often the last teeth to be lost in the ageing dentition and serve as important abutments in prosthodontics.

Question 98: Which structure appears as a radiolucent band across the roots of maxillary teeth on a DPT (OPG)?

Nasal septum
Air shadow of the oropharynx (Correct answer)
Hard palate shadow
Maxillary sinus floor

Correct answer: Air shadow of the oropharynx

The oropharyngeal airway creates a characteristic radiolucent (dark) band that is superimposed across the roots of the anterior teeth on a DPT. This is a normal anatomical shadow and should not be confused with pathology. Asking the patient to place their tongue against the palate during exposure helps reduce this artefact.

Question 99: Which component in ZOE-based root canal sealers is primarily responsible for periapical tissue cytotoxicity?

Eugenol (Correct answer)
Zinc oxide powder
Titanium dioxide
Rosin

Correct answer: Eugenol

Eugenol is the cytotoxic component in ZOE-based sealers; it causes tissue irritation, inhibits pulp cell proliferation, and is toxic to periapical tissues when in direct contact.

Question 100: What is the most common complication following extraction of maxillary molars?

Inferior alveolar nerve damage
Oroantral communication (Correct answer)
Mandibular fracture
Ludwig's angina

Correct answer: Oroantral communication

Oroantral communication (OAC) is the most common complication of upper molar extractions due to the close relationship between the molar roots and the maxillary sinus floor. If the OAC is less than 2mm, it may close spontaneously; larger communications require surgical closure with a buccal advancement flap.

ORE Part 1 Dental Exam

The GDC Overseas Registration Exam Part 1 tests overseas-qualified dentists on clinically applied dental science, human disease, and clinical dentistry subjects required to practise in the UK.

100

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180 min

Time Limit

50%

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