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HK Dental ORE practice questions

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Question 1Part I Written Test

A 45-year-old patient attends for a restoration. On examination the dentist suspects a bleeding disorder. Which history feature is MOST important to establish before any invasive dental procedure?

  1. Daily use of a chlorhexidine mouthrinse
  2. A family history of hypertension
  3. Previous episodes of prolonged bleeding after extraction or surgery Correct answer.
  4. Occasional use of ibuprofen for headache

Explanation

A documented personal history of prolonged bleeding after previous surgery or extraction is the single most predictive screening question for an underlying bleeding tendency. It directly reflects the patient's haemostatic competence under surgical challenge, which is precisely the situation the planned procedure will reproduce.

Question 2Part I Written Test

Which local anaesthetic agent is contraindicated in a patient with a documented true allergy to ester-type anaesthetics?

  1. Articaine
  2. Benzocaine Correct answer.
  3. Lidocaine
  4. Mepivacaine

Explanation

Benzocaine is an ester-linked local anaesthetic and shares the para-aminobenzoic acid metabolite that mediates ester hypersensitivity. Amide agents such as lidocaine, articaine and mepivacaine are structurally unrelated and are generally safe in ester-allergic patients.

Question 3Part I Written Test

A patient on long-term warfarin attends for a single simple extraction. The INR is 2.8. What is the MOST appropriate management?

  1. Proceed with the extraction with local haemostatic measures Correct answer.
  2. Refer for hospital admission and intravenous vitamin K
  3. Double the warfarin dose on the morning of surgery
  4. Stop warfarin five days preoperatively without substitution

Explanation

An INR of 2.8 lies within the therapeutic range in which simple extractions can usually be performed safely in primary care, provided local measures such as suturing, haemostatic packing and tranexamic acid mouthwash are used. Warfarin should not be stopped for routine minor surgery because the thrombotic risk outweighs the bleeding risk.

Question 4Part I Written Test

Which radiographic feature is characteristic of a periapical cyst rather than a periapical granuloma?

  1. Generalised widening of the periodontal ligament space only
  2. Ill-defined border with a mixed radiolucent-radiopaque pattern
  3. Diffuse sclerosis of the surrounding alveolar bone
  4. Well-defined corticated border with a uniform radiolucency Correct answer.

Explanation

A periapical cyst typically shows a well-circumscribed, uniformly radiolucent lesion with a corticated margin, reflecting slow expansile growth lined by epithelium. A granuloma usually has a less well defined border and is smaller, though radiography alone cannot reliably distinguish the two.

Question 5Part I Written Test

According to the Basic Periodontal Examination, a code 4 indicates which finding?

  1. Bleeding on probing only
  2. Furcation involvement with pocketing less than 3.5 mm
  3. Pocket depth of 3.5 to 5.5 mm
  4. Pocket depth of 6 mm or more Correct answer.

Explanation

In the BPE scoring system, code 4 denotes a probing depth of 6 mm or greater in at least one sextant, which mandates full periodontal assessment and treatment. Code 3 covers depths of 3.5 to 5.5 mm.

Question 6Part I Written Test

A patient reports a sudden onset of severe, sharp, lancinating pain in the lower jaw lasting seconds, triggered by touching the lip. Which diagnosis is MOST likely?

  1. Temporomandibular joint arthralgia
  2. Trigeminal neuralgia Correct answer.
  3. Atypical odontalgia
  4. Pulpitis of the lower molar

Explanation

Brief, electric-shock-like pain triggered by light tactile stimuli in a trigeminal distribution is the classic presentation of trigeminal neuralgia. The absence of a dental cause and the very short duration of each paroxysm distinguish it from odontogenic pain.

Question 7Part I Written Test

Which organism is most strongly associated with the initiation of dental caries?

  1. Treponema denticola
  2. Candida albicans
  3. Streptococcus mutans Correct answer.
  4. Porphyromonas gingivalis

Explanation

Streptococcus mutans is a key cariogenic organism because it adheres to enamel, ferments dietary sugars and produces acid that demineralises tooth structure. The other listed organisms are principally associated with periodontal disease or fungal infection.

Question 8Part I Written Test

What is the principal mechanism by which topical fluoride reduces caries progression?

  1. Promotion of remineralisation and inhibition of demineralisation at the tooth surface Correct answer.
  2. Direct bactericidal killing of all plaque flora
  3. Systemic incorporation into developing enamel only
  4. Neutralisation of gastric acid

Explanation

Topical fluoride acts mainly through the formation of fluorapatite and calcium fluoride reservoirs, enhancing remineralisation and reducing demineralisation when acid challenges occur. Its antibacterial effect is modest and secondary, and it does not sterilise plaque.

Question 9Part I Written Test

A 12-year-old presents with a permanent maxillary central incisor that has been avulsed and stored dry for 90 minutes. What is the MOST appropriate immediate action?

  1. Place the tooth in milk and delay replantation by 24 hours
  2. Replant the tooth without any cleaning or handling precautions
  3. Discard the tooth and plan an implant
  4. Replant the tooth after soaking in saline and splint it Correct answer.

Explanation

Even with a prolonged extraoral dry time, replantation remains the preferred option because it preserves alveolar bone and offers some chance of periodontal healing. Gentle handling, brief saline soak and a flexible splint are appropriate, and the patient should be reviewed for possible root resorption.

Question 10Part I Written Test

Which tooth is most frequently impacted in the permanent dentition?

  1. Maxillary central incisor
  2. Maxillary canine
  3. Mandibular second premolar
  4. Mandibular third molar Correct answer.

Explanation

Mandibular third molars are the most commonly impacted teeth, largely because of insufficient space in the retromolar region. Maxillary canines are the second most common but occur far less frequently.

Question 11Part I Written Test

Which clinical sign best distinguishes a malignant oral ulcer from a traumatic one?

  1. A history of recent trauma from a sharp tooth
  2. Induration with rolled everted margins and no response to removing irritants Correct answer.
  3. Presence of a yellowish fibrinous centre
  4. A well-defined ulcer that heals within two weeks of removing the cause

Explanation

Malignant ulcers characteristically have indurated, rolled and everted margins and fail to heal after removal of any obvious irritant. Traumatic ulcers typically have a clear cause and resolve within about two weeks once the cause is eliminated.

Question 12Part I Written Test

Which of the following is a recognised oral manifestation of Crohn's disease?

  1. Generalised gingival enlargement from birth
  2. Cobblestone mucosal appearance with linear ulceration Correct answer.
  3. Diffuse melanin pigmentation of the gingiva
  4. Periapical cemento-osseous dysplasia

Explanation

Crohn's disease may produce oral changes including a cobblestone appearance of the mucosa, linear ulcers and mucosal tags, reflecting granulomatous inflammation. These findings can precede intestinal symptoms and are useful diagnostic clues.

Question 13Part I Written Test

A patient with poorly controlled type 1 diabetes attends for periodontal treatment. Which statement best describes the relationship between diabetes and periodontitis?

  1. Periodontitis worsens glycaemic control and treatment may improve it Correct answer.
  2. Diabetes protects against periodontal destruction
  3. Periodontitis has no effect on glycaemic control
  4. Periodontal treatment is contraindicated in all diabetic patients

Explanation

The relationship between diabetes and periodontitis is bidirectional: hyperglycaemia increases susceptibility to periodontal destruction, while chronic periodontal inflammation contributes to insulin resistance. Periodontal therapy has been associated with modest improvements in glycaemic control.

Question 14Part I Written Test

Which of the following is the most appropriate first-line management for a patient with recurrent aphthous stomatitis?

  1. Topical corticosteroid preparations and identification of trigger factors Correct answer.
  2. Prophylactic antibiotics
  3. Radical surgical excision of the affected mucosa
  4. Long-term systemic corticosteroids

Explanation

Recurrent aphthous stomatitis is usually managed with topical corticosteroids to reduce pain and duration, alongside attention to possible triggering factors such as trauma, stress or nutritional deficiency. Systemic therapy is reserved for severe refractory cases.

Question 15Part I Written Test

Which is the most reliable method for confirming the diagnosis of oral lichen planus?

  1. Salivary pH measurement
  2. Clinical appearance alone
  3. Serum IgE levels
  4. Incisional biopsy with histopathological and immunofluorescence assessment Correct answer.

Explanation

Although the clinical pattern of bilateral white striae is suggestive, a biopsy with histopathology and direct immunofluorescence is needed to exclude mimics such as lichenoid reactions and dysplasia. Immunofluorescence helps distinguish lichen planus from other vesiculobullous diseases.

Question 16Part I Written Test

A patient requires a restoration in a tooth with a deep carious lesion. Which pulp diagnosis is consistent with a reversible pulpitis?

  1. Sharp pain provoked by cold that resolves quickly after the stimulus is removed Correct answer.
  2. Spontaneous, unprovoked throbbing pain that wakes the patient at night
  3. Pain on biting with a sinus tract present
  4. No response to thermal testing with a periapical radiolucency

Explanation

Reversible pulpitis produces provoked pain that subsides promptly once the stimulus is removed, indicating the pulp remains vital and capable of recovery. Spontaneous or persistent pain suggests irreversible pulpitis.

Question 17Part I Written Test

Which file sequence best describes the concept of crown-down preparation in root canal treatment?

  1. Preparing the apical third before the coronal third
  2. Using only hand files without irrigation
  3. Starting with the smallest file at the apex and enlarging sequentially
  4. Starting with larger files at the coronal aspect and progressing to smaller files apically Correct answer.

Explanation

Crown-down preparation begins with larger instruments in the coronal portion of the canal and progressively uses smaller instruments towards the apex. This approach improves access, reduces extrusion of contaminated debris and allows earlier irrigation of the canal.

Question 18Part I Written Test

Which of the following is a principal advantage of a resin-bonded bridge over a conventional fixed bridge for replacing a single anterior tooth?

  1. It eliminates the need for any tooth preparation
  2. It requires minimal reduction of the abutment teeth Correct answer.
  3. It is suitable when there is severe abutment mobility
  4. It has a higher long-term success rate than implants

Explanation

Resin-bonded bridges rely on minimal or no preparation of the abutment teeth, preserving sound enamel and remaining conservative. Their success depends on adequate enamel bonding and stable abutments, and they are not indicated where abutment mobility is severe.

Question 19Part I Written Test

What is the main purpose of a night guard in a patient with sleep bruxism?

  1. To permanently alter the occlusion
  2. To protect teeth and restorations from excessive forces Correct answer.
  3. To eliminate the need for stress management
  4. To cure the underlying neurological cause

Explanation

An occlusal splint protects the dentition and restorations from the wear and fracture associated with nocturnal bruxism. It does not address the central neurological drive behind bruxism and is not a definitive cure.

Question 20Part I Written Test

Which of the following best describes the mechanism of action of chlorhexidine as an adjunct in periodontal therapy?

  1. It acts as a systemic antibiotic against periodontal pathogens
  2. It inhibits cyclo-oxygenase and reduces inflammation directly
  3. It chelates calcium and prevents plaque mineralisation only
  4. It disrupts bacterial cell membranes and has substantivity on oral surfaces Correct answer.

Explanation

Chlorhexidine is a cationic bisbiguanide that disrupts bacterial cytoplasmic membranes and binds to oral surfaces, giving prolonged substantivity. This residual binding explains its persistent antiplaque effect compared with other mouthrinses.

Question 21Part I Written Test

A patient presents with a unilateral swelling of the floor of the mouth that is soft and fluctuant. Which structure is most at risk if the swelling is a ranula?

  1. The facial artery
  2. The hypoglossal nerve
  3. The lingual nerve
  4. The submandibular duct Correct answer.

Explanation

A ranula arises from the sublingual gland and can compress or obstruct the submandibular duct, causing salivary obstruction. This is why ranulae may present with swelling of the submandibular region as well as the floor of the mouth.

Question 22Part I Written Test

Which of the following is the most appropriate management for a patient with a suspected odontogenic infection causing submandibular space swelling and difficulty swallowing?

  1. Extraction under local anaesthesia in primary care without further assessment
  2. Urgent referral for airway assessment and drainage Correct answer.
  3. Oral antibiotics and review in one week
  4. Reassurance and analgesia only

Explanation

Swelling involving the submandibular space with difficulty swallowing raises concern about airway compromise and spread of infection, requiring urgent hospital assessment and drainage. Delay in managing such fascial space infections can be life-threatening.

Question 23Part I Written Test

Which of the following is a recognised radiographic feature of fibrous dysplasia of the jaws?

  1. A ground-glass appearance with blending into surrounding bone Correct answer.
  2. A multilocular soap-bubble radiolucency
  3. A well-defined radiolucency with a corticated border
  4. A sunburst periosteal reaction

Explanation

Fibrous dysplasia typically produces a ground-glass or orange-peel appearance in which the lesional margins blend with surrounding bone. This reflects the replacement of normal bone by fibro-osseous tissue.

Question 24Part I Written Test

Which of the following best explains why a patient with a history of infective endocarditis may require antibiotic prophylaxis before dental extraction?

  1. To prevent periodontal disease progression
  2. To reduce the risk of local alveolar osteitis
  3. To sterilise the oral cavity permanently
  4. To prevent bacteraemia from causing infection of the cardiac lesion Correct answer.

Explanation

Antibiotic prophylaxis aims to reduce the transient bacteraemia associated with invasive dental procedures, which can seed a susceptible cardiac lesion and cause endocarditis. It is targeted at high-risk patients rather than used routinely for all patients.

Question 25Part I Written Test

A 30-year-old patient reports a history of recurrent swelling of the parotid gland that occurs with meals and subsides afterwards. Which diagnosis is MOST likely?

  1. Salivary duct obstruction such as a sialolith Correct answer.
  2. Parotid malignancy
  3. Sjögren syndrome
  4. Acute suppurative parotitis

Explanation

Mealtime-related swelling that subsides afterwards is characteristic of an obstructive cause such as a salivary stone, which causes saliva to accumulate against the obstruction. The cyclical pattern distinguishes it from neoplastic or inflammatory disease.

Question 26Part I Written Test

In the FDI two-digit system, which tooth is represented by the number 36?

  1. Mandibular left second premolar
  2. Maxillary left first molar
  3. Mandibular right first molar
  4. Mandibular left first molar Correct answer.

Explanation

The FDI system uses two digits: the first digit denotes the quadrant (1-4 for permanent maxillary right, maxillary left, mandibular left, mandibular right) and the second digit denotes the tooth position from the midline (1-8). For 36, the first digit 3 indicates the mandibular left quadrant and the second digit 6 indicates the first molar. Therefore, 36 is the mandibular left first molar.

Question 27Part I Written Test

Which permanent tooth typically has the most variable number of cusps, ranging from three to five?

  1. Maxillary central incisor
  2. Mandibular second molar Correct answer.
  3. Mandibular first premolar
  4. Maxillary first molar

Explanation

The mandibular second molar is known for its variable occlusal morphology, commonly having four cusps but frequently displaying three (Y-shaped groove pattern) or five cusps. This variability is greater than that seen in other posterior teeth. The maxillary first molar typically has four cusps plus the cusp of Carabelli, while premolars and incisors have more consistent cusp numbers.

Question 28Part I Written Test

Which cranial nerve provides general sensory innervation to the anterior two-thirds of the tongue?

  1. Lingual nerve (branch of mandibular division of trigeminal, CN V3) Correct answer.
  2. Facial nerve (CN VII)
  3. Hypoglossal nerve (CN XII)
  4. Glossopharyngeal nerve (CN IX)

Explanation

General sensation (touch, temperature, pain) from the anterior two-thirds of the tongue is carried by the lingual nerve, a branch of the mandibular division of the trigeminal nerve (CN V3). Taste to this region is provided by the chorda tympani branch of the facial nerve (CN VII). The glossopharyngeal nerve supplies general and taste sensation to the posterior third.

Question 29Part I Written Test

During administration of an inferior alveolar nerve block, which anatomical structure is most at risk of inadvertent needle injury if the needle is inserted too posteriorly?

  1. Submandibular duct
  2. Parotid gland Correct answer.
  3. Facial artery
  4. Lingual nerve

Explanation

The parotid gland is located posterior to the mandibular ramus. If the needle is inserted too far posteriorly during an inferior alveolar nerve block, it can enter the parotid gland and potentially deposit solution there, leading to facial nerve palsy. The lingual nerve is at risk if the needle is placed too medially, and the facial artery is not typically in the path of this injection.

Question 30Part I Written Test

Which local anaesthetic agent is contraindicated in a patient with a known allergy to esters and has the lowest risk of allergic reaction?

  1. Procaine
  2. Articaine
  3. Benzocaine
  4. Lidocaine Correct answer.

Explanation

Lidocaine is an amide-type local anaesthetic, and amides have a very low incidence of true allergic reactions compared with esters. Esters such as procaine and benzocaine are more likely to cause allergic reactions due to their metabolism to para-aminobenzoic acid (PABA). Articaine, although an amide, contains a thiophene ring and is not the first choice in ester-allergic patients due to potential cross-reactivity, though true allergy is rare.

Question 31Part I Written Test

Which of the following is the most common cause of failure of a direct composite restoration in a posterior tooth?

  1. Marginal staining
  2. Secondary caries Correct answer.
  3. Bulk fracture
  4. Post-operative sensitivity

Explanation

Secondary caries (recurrent caries) at the restoration margins is the most frequent reason for replacement of posterior composite restorations. Marginal staining and post-operative sensitivity are common but do not usually necessitate replacement. Bulk fracture occurs less frequently with modern composites and proper technique.

Question 32Part I Written Test

Which of the following best describes the term 'abfraction' in relation to non-carious cervical lesions?

  1. Abrasion from excessive toothbrushing
  2. Loss of tooth structure due to chemical dissolution
  3. Wedge-shaped defect caused by eccentric occlusal forces Correct answer.
  4. Cervical lesion caused by acid reflux

Explanation

Abfraction is a wedge-shaped cervical lesion believed to result from flexure and fatigue of enamel and dentine under eccentric occlusal loading. It is distinguished from erosion (chemical dissolution), abrasion (mechanical wear), and attrition (tooth-tooth wear). The characteristic shape and location support a biomechanical aetiology.

Question 33Part I Written Test

Which of the following is the primary advantage of using a rubber dam during endodontic treatment?

  1. Improved visibility of the operating field
  2. Isolation of the tooth from oral fluids and prevention of ingestion of instruments Correct answer.
  3. Reduction of aerosol contamination
  4. Better retention of the access cavity

Explanation

The main advantage of rubber dam isolation in endodontics is to provide a dry, clean field by isolating the tooth from saliva and oral fluids, and to prevent aspiration or ingestion of small instruments and irrigants. While it also improves visibility and reduces aerosol, these are secondary benefits. Retention of the access cavity is not affected.

Question 34Part I Written Test

A patient presents with a sinus tract (gumboil) associated with a previously root-treated tooth. The radiograph shows a periapical radiolucency and a missed canal. What is the most appropriate management?

  1. Non-surgical root canal retreatment Correct answer.
  2. Extraction and implant placement
  3. Antibiotic therapy alone
  4. Apicectomy without retreatment

Explanation

The presence of a sinus tract and periapical radiolucency with a missed canal indicates persistent infection. The first-line treatment is non-surgical root canal retreatment to address the missed canal and eliminate the infection. Apicectomy is considered only if retreatment is not feasible or has failed. Antibiotics alone are insufficient and not indicated for chronic apical periodontitis.

Question 35Part I Written Test

Which of the following is the most important prognostic factor for a successful replantation of an avulsed permanent tooth?

  1. Extra-oral dry time Correct answer.
  2. Patient's age
  3. Use of systemic antibiotics
  4. Type of splint used

Explanation

The extra-oral dry time is the most critical determinant of periodontal ligament cell viability and thus the prognosis for replantation. The shorter the dry time, the better the chance of success. Splint type, antibiotics, and age are secondary factors. Immediate replantation or storage in a suitable medium is essential.

Question 36Part I Written Test

A 10-year-old child sustains a luxation injury to a permanent maxillary central incisor. The tooth is mobile and displaced lingually. Which of the following is the most appropriate immediate management?

  1. Observation only
  2. Root canal treatment within 2 weeks
  3. Repositioning and flexible splinting Correct answer.
  4. Extraction of the tooth

Explanation

For a luxated permanent tooth with displacement, the immediate management is to reposition the tooth and apply a flexible splint to stabilise it. Root canal treatment is indicated only if the pulp becomes necrotic, which is assessed later. Extraction is not indicated for a viable luxated tooth. Observation alone would leave the tooth in a malposition.

Question 37Part I Written Test

Which of the following is the most common cause of peri-implantitis?

  1. Systemic diseases such as diabetes
  2. Bacterial biofilm accumulation Correct answer.
  3. Allergic reaction to titanium
  4. Excessive occlusal loading

Explanation

Peri-implantitis is an inflammatory disease of the tissues around dental implants, primarily caused by bacterial biofilm accumulation, similar to periodontitis. Occlusal overload and systemic factors may contribute but are not the primary cause. Allergy to titanium is extremely rare and not a common cause.

Question 38Part I Written Test

A patient with a history of infective endocarditis is scheduled for a dental extraction. According to current guidelines, which of the following is the most appropriate antibiotic prophylaxis regimen?

  1. Clindamycin 600 mg orally 1 hour before the procedure
  2. No prophylaxis is required
  3. Amoxicillin 500 mg orally 1 hour before the procedure
  4. Amoxicillin 2 g orally 1 hour before the procedure Correct answer.

Explanation

Current guidelines recommend a single 2 g dose of amoxicillin orally 1 hour before the procedure for patients with a history of infective endocarditis undergoing high-risk dental procedures. If allergic to penicillin, alternatives include cephalexin, azithromycin, or doxycycline. Clindamycin is no longer recommended due to adverse effects.

Question 39Part I Written Test

Which of the following is the first-line treatment for a patient with symptomatic trigeminal neuralgia?

  1. Carbamazepine Correct answer.
  2. Amitriptyline
  3. Gabapentin
  4. Ibuprofen

Explanation

Carbamazepine is the first-line medication for trigeminal neuralgia, providing significant pain relief in most patients. Other medications such as gabapentin or amitriptyline may be used as adjuncts or second-line. Ibuprofen is ineffective for neuropathic pain.

Question 40Part I Written Test

A patient presents with a painless, fluctuant swelling in the midline of the floor of the mouth that transilluminates. Which of the following is the most likely diagnosis?

  1. Thyroglossal duct cyst
  2. Ranula Correct answer.
  3. Submandibular sialolith
  4. Dermoid cyst

Explanation

A ranula is a mucocele arising from the sublingual gland, presenting as a painless, fluctuant, bluish swelling in the floor of the mouth that transilluminates. A dermoid cyst is usually midline but not fluctuant or transilluminant. A sialolith is hard and may cause pain. A thyroglossal duct cyst presents in the neck, not the floor of the mouth.

Question 41Part I Written Test

Which of the following is a characteristic feature of oral lichen planus?

  1. Pseudomembranous white plaques that wipe off
  2. Unilateral ulceration with indurated borders
  3. Multiple vesicles that rupture to form crusts
  4. White striae (Wickham's striae) on the buccal mucosa Correct answer.

Explanation

Oral lichen planus typically presents with white, lacy striae (Wickham's striae) on the buccal mucosa, often bilateral. Pseudomembranous plaques that wipe off are characteristic of candidiasis. Unilateral indurated ulceration suggests malignancy. Vesicles are seen in conditions such as pemphigus or herpes.

Question 42Part I Written Test

A patient with poorly controlled diabetes mellitus is at increased risk of which of the following oral complications?

  1. Decreased incidence of xerostomia
  2. Delayed wound healing and increased susceptibility to infection Correct answer.
  3. Reduced risk of periodontal disease
  4. Increased caries resistance

Explanation

Poorly controlled diabetes impairs wound healing and increases susceptibility to infection due to compromised immune function and microvascular changes. It also increases the risk and severity of periodontal disease and xerostomia. It does not increase caries resistance.

Question 43Part I Written Test

Which of the following is the most appropriate radiographic examination for a new adult patient with no specific complaints, according to the FGDP(UK) selection criteria?

  1. Periapical radiographs of all teeth
  2. No radiographs are indicated
  3. Panoramic radiograph
  4. Bitewing radiographs Correct answer.

Explanation

For a new adult patient with no specific complaints, bitewing radiographs are indicated to detect interproximal caries and bone loss. A panoramic radiograph is not routinely indicated unless there is a specific clinical indication. Periapical radiographs of all teeth are not justified without clinical findings.

Question 44Part I Written Test

Which of the following is a recognised radiographic feature of ameloblastoma?

  1. Cotton-wool radiopacity
  2. Soap-bubble multilocular radiolucency Correct answer.
  3. Ground-glass appearance
  4. Sun-ray spiculation

Explanation

Ameloblastoma often presents as a multilocular radiolucency with a soap-bubble appearance, typically in the posterior mandible. Ground-glass appearance is characteristic of fibrous dysplasia. Sun-ray spiculation suggests osteosarcoma. Cotton-wool radiopacity is seen in Paget's disease or cemento-osseous dysplasia.

Question 45Part I Written Test

Which of the following is the most appropriate treatment for a mandibular fracture in a child with mixed dentition?

  1. Immediate extraction of teeth in the fracture line
  2. Observation only
  3. Open reduction and internal fixation with plates and screws
  4. Closed reduction with maxillomandibular fixation using circummandibular wiring Correct answer.

Explanation

In children with mixed dentition, conservative management with closed reduction and immobilisation is preferred to avoid damage to developing teeth. Open reduction with plates and screws risks injury to tooth germs. Observation alone is insufficient for a displaced fracture. Extraction of teeth is not routinely indicated.

Question 46Part I Written Test

A patient is scheduled for surgical removal of an impacted mandibular third molar. Which of the following is the most important preoperative assessment to minimise the risk of inferior alveolar nerve injury?

  1. Measurement of mouth opening
  2. Assessment of the relationship of the tooth roots to the mandibular canal on CBCT Correct answer.
  3. Assessment of the patient's anxiety level
  4. Routine panoramic radiograph only

Explanation

Cone beam computed tomography (CBCT) provides three-dimensional imaging to assess the proximity of the tooth roots to the mandibular canal, helping to minimise the risk of inferior alveolar nerve injury. A panoramic radiograph alone may not show the relationship accurately. Mouth opening and anxiety are relevant but not for nerve injury risk.

Question 47Part I Written Test

Which of the following is the most common complication following surgical extraction of a mandibular third molar?

  1. Inferior alveolar nerve injury
  2. Alveolar osteitis (dry socket) Correct answer.
  3. Mandibular fracture
  4. Lingual nerve injury

Explanation

Alveolar osteitis, or dry socket, is the most common complication after surgical extraction of a mandibular third molar, characterised by severe pain and loss of the blood clot. Nerve injuries and mandibular fracture are less common but more serious. Proper postoperative instructions can reduce the risk of dry socket.

Question 48Part I Written Test

Which of the following is the most appropriate management for a patient with a displaced crown-root fracture of a permanent incisor with pulp involvement?

  1. Extraction and immediate implant placement
  2. No treatment
  3. Repositioning and splinting only
  4. Root canal treatment and restoration Correct answer.

Explanation

A crown-root fracture with pulp involvement requires endodontic treatment if the pulp is exposed and the tooth is restorable. The fractured segment may be removed, and the tooth restored. Extraction is indicated only if the tooth is unrestorable. Splinting alone does not address the pulp involvement.

Question 49Part I Written Test

Which of the following is the primary mechanism of action of sodium hypochlorite as an endodontic irrigant?

  1. Lubrication of the canal
  2. Antimicrobial and tissue-dissolving properties Correct answer.
  3. Chelation of calcium ions
  4. Removal of the smear layer

Explanation

Sodium hypochlorite is the most widely used endodontic irrigant due to its broad-spectrum antimicrobial activity and its ability to dissolve necrotic tissue and organic debris. Chelation of calcium ions is achieved by EDTA. Lubrication is provided by chelating agents or lubricants. Removal of the smear layer requires EDTA in combination with sodium hypochlorite.

Question 50Part I Written Test

Which of the following is the most appropriate treatment for a patient with a Class II division 1 malocclusion with an overjet of 10 mm and a normal skeletal pattern?

  1. Functional appliance therapy
  2. Fixed appliance therapy with premolar extractions Correct answer.
  3. Observation only
  4. Orthognathic surgery

Explanation

For a Class II division 1 malocclusion with a large overjet and a normal skeletal pattern, fixed appliance therapy with premolar extractions is often indicated to reduce the overjet and correct the malocclusion. Functional appliances are more suitable for growing patients with skeletal discrepancies. Orthognathic surgery is reserved for severe skeletal discrepancies. Observation would not address the functional and aesthetic concerns.