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MOH Oral and Dental Health Licensure Exam (Jordan) study materials
MOH Oral and Dental Health Licensure Exam (Jordan) study resources

MOH Oral and Dental Health Licensure Exam (Jordan) practice questions

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Question 1Oral Anatomy, Histology and Embryology

According to the FDI two-digit notation system, which number designates the permanent mandibular right first molar?

  1. 46 Correct answer.
  2. 47
  3. 45
  4. 36

Explanation

In the FDI system, the first digit identifies the quadrant and the second digit identifies the tooth position counted from the midline. The permanent mandibular right quadrant is quadrant 4, and the first molar is position 6, giving the number 46.

Question 2Oral Anatomy, Histology and Embryology

Which primary tooth is usually the first to erupt in the oral cavity?

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

Explanation

The primary mandibular central incisors are typically the first teeth to emerge, at approximately 6 to 10 months of age. Eruption generally follows a pattern in which mandibular teeth precede their maxillary counterparts.

Question 3Oral Anatomy, Histology and Embryology

Which salivary gland is the largest and produces primarily serous saliva?

  1. Parotid gland Correct answer.
  2. Minor salivary glands
  3. Submandibular gland
  4. Sublingual gland

Explanation

The parotid gland is the largest major salivary gland, and its secretion is predominantly serous. It contributes about 20% of resting saliva but a larger proportion of stimulated saliva.

Question 4Oral Anatomy, Histology and Embryology

During root formation, Hertwig's epithelial root sheath induces differentiation of cells that first deposit which hard tissue?

  1. Cementum
  2. Root dentin Correct answer.
  3. Enamel
  4. Alveolar bone

Explanation

Hertwig's epithelial root sheath induces dental papilla cells to differentiate into odontoblasts, which secrete root dentin. After the first layer of dentin forms, the root sheath breaks up and cementoblasts deposit cementum on the dentin surface.

Question 5Oral Anatomy, Histology and Embryology

Which principal fiber group of the periodontal ligament is most important for resisting intrusive forces on a tooth?

  1. Alveolar crest fibers
  2. Oblique fibers Correct answer.
  3. Horizontal fibers
  4. Apical fibers

Explanation

Oblique fibers run from the alveolar bone crest obliquely to the root and are the most numerous group. They convert intrusive forces into tension on the bone, making them the principal resistance to axial loading.

Question 6Oral Anatomy, Histology and Embryology

In the bell stage of tooth development, which cell layer differentiates directly into ameloblasts?

  1. Dental papilla
  2. Outer enamel epithelium
  3. Stellate reticulum
  4. Inner enamel epithelium Correct answer.

Explanation

The inner enamel epithelium is the layer adjacent to the dental papilla, and its cells differentiate into ameloblasts. These cells will secrete the enamel matrix after dentin begins to form at the dentinoenamel junction.

Question 7Oral Anatomy, Histology and Embryology

The articular disc of the temporomandibular joint is composed primarily of which tissue?

  1. Fibrocartilage Correct answer.
  2. Hyaline cartilage
  3. Elastic cartilage
  4. Compact bone

Explanation

The temporomandibular joint disc is made of dense fibrous connective tissue with fibrocartilage, which better withstands compression and shear than hyaline cartilage. Hyaline cartilage covers the articular surfaces of most other synovial joints but not the TMJ.

Question 8Oral Anatomy, Histology and Embryology

At the cementoenamel junction of adult teeth, which relationship is observed most frequently?

  1. Cementum and enamel meet edge-to-edge
  2. Enamel overlaps cementum
  3. Cementum overlaps enamel Correct answer.
  4. Dentin is exposed between cementum and enamel

Explanation

In approximately 60% of teeth, cementum overlaps the cervical enamel. Edge-to-edge meeting occurs in about 30%, and a gap exposing dentin is seen in about 10%, while enamel overlapping cementum is least common.

Question 9Oral Anatomy, Histology and Embryology

Hunter-Schreger bands in enamel are primarily caused by which structural feature?

  1. Incremental lines of Retzius
  2. Odontoblast processes crossing the dentinoenamel junction
  3. Alternating directions of enamel rods in adjacent layers Correct answer.
  4. Perikymata on the enamel surface

Explanation

Hunter-Schreger bands appear as alternating light and dark bands because groups of enamel rods change direction in adjacent layers, a phenomenon called decussation. They are distinct from incremental lines of Retzius and from surface perikymata.

Question 10Oral Anatomy, Histology and Embryology

Which permanent tooth is usually the first to erupt in the mandibular arch?

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

Explanation

The permanent mandibular first molar typically erupts at about 6 years of age, often before any primary tooth is shed. It is therefore often considered the first permanent tooth to erupt, with the mandibular central incisor following at around 6 to 7 years.

Question 11Oral Anatomy, Histology and Embryology

In the developing tooth germ, which mineralized tissue is deposited first at any given site, before the other hard tissues of the tooth appear?

  1. Dentin Correct answer.
  2. Enamel
  3. Cementum
  4. Alveolar bone

Explanation

Dentin is the first mineralized tissue formed in the tooth germ. Odontoblasts differentiate and secrete predentin along the future dentinoenamel junction, and once a layer of dentin is present the ameloblasts begin to deposit enamel against it. This is why dentin always slightly precedes enamel at each site of crown formation, and why cementum and alveolar bone, which belong to the root and supporting apparatus, appear much later.

Question 12Oral Anatomy, Histology and Embryology

Which papillae on the dorsum of the tongue are heavily keratinized, give the tongue its rough surface texture, and contain no taste buds?

  1. Fungiform papillae
  2. Filiform papillae Correct answer.
  3. Foliate papillae
  4. Circumvallate papillae

Explanation

Filiform papillae are the most numerous papillae on the tongue dorsum; they are conical, keratinized and mechanically oriented, contributing to the abrasive surface used in food manipulation. They carry no taste buds, which is why they are classified as mechanical rather than gustatory papillae. Fungiform, circumvallate and foliate papillae all contain taste buds and are associated with taste function.

Question 13Oral Anatomy, Histology and Embryology

A patient is asked to thrust the chin forward. Which muscle is the principal producer of this mandibular protrusion when it contracts bilaterally?

  1. Medial pterygoid
  2. Lateral pterygoid Correct answer.
  3. Masseter
  4. Temporalis

Explanation

The lateral pterygoid has an almost horizontal pull that draws the condyle and articular disc forward, so bilateral contraction protrudes the mandible and also depresses it when the mouth opens. The other masticatory muscles are predominantly elevators, with the temporalis additionally retruding the mandible.

Question 14Oral Anatomy, Histology and Embryology

Which permanent tooth most commonly has three cusps, one buccal and two lingual, with an occlusal outline that is often U- or H-shaped?

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

Explanation

The mandibular second premolar is the premolar that most often carries three cusps, one buccal and two lingual, with a Y-shaped or U-shaped occlusal pattern in its common three-cusp form. The mandibular first premolar has two cusps with a small lingual cusp, and maxillary premolars typically show two cusps.

Question 15Oral Anatomy, Histology and Embryology

In a histological section of mature dental pulp, which zone lies immediately beneath the odontoblast layer and is characterized by few cells but a rich capillary and nerve plexus?

  1. Cell-rich zone
  2. Central core of the pulp
  3. Odontoblastic layer
  4. Cell-free zone of Weil Correct answer.

Explanation

The cell-free zone of Weil is the narrow, pale band just deep to the odontoblast layer. It is poor in cells but contains the plexus of Raschkow, the network of nerves and capillaries that supplies the odontoblast region. The cell-rich zone lies deeper to it and contains numerous fibroblasts and undifferentiated mesenchymal cells.

Question 16Oral Anatomy, Histology and Embryology

The mucous membrane covering the root (base) of the tongue develops mainly from which pharyngeal arches?

  1. Third and fourth arches Correct answer.
  2. First and second arches
  3. Second and third arches
  4. Fourth and sixth arches

Explanation

The anterior two-thirds of the tongue arises from the first arch through the tuberculum impar and lateral lingual swellings, while the root or base of the tongue develops from the third and fourth arches in the region of the copula. This dual origin explains the different sensory innervation of the two parts, with the boundary marked by the sulcus terminalis.

Question 17Oral Pathology and Oral Medicine

Which of the following is the most common odontogenic cyst of the jaws?

  1. Radicular cyst Correct answer.
  2. Glandular odontogenic cyst
  3. Dentigerous cyst
  4. Odontogenic keratocyst

Explanation

The radicular (periapical) cyst is the most common odontogenic cyst. It develops from epithelial rests of Malassez within a periapical granuloma after pulp necrosis, producing a well-defined radiolucency at the apex of a non-vital tooth.

Question 18Oral Pathology and Oral Medicine

Which intraoral site is most frequently affected by oral squamous cell carcinoma?

  1. Lateral tongue Correct answer.
  2. Retromolar pad
  3. Hard palate
  4. Buccal mucosa

Explanation

Oral squamous cell carcinoma most often arises on the lateral border of the tongue, with the floor of the mouth following closely. These dependent sites pool saliva carrying tobacco and alcohol carcinogens and are lined by thin, non-keratinized mucosa that provides little barrier.

Question 19Oral Pathology and Oral Medicine

A patient reports recurrent crops of grouped vesicles at the vermilion border that crust and heal within one week, typically after sun exposure. Which virus is responsible?

  1. Varicella-zoster virus
  2. Coxsackievirus A16
  3. Herpes simplex virus 1 Correct answer.
  4. Human papillomavirus type 16

Explanation

Recurrent herpes labialis results from reactivation of herpes simplex virus 1, which lies latent in the trigeminal ganglion. Sunlight, stress, fever and local trauma trigger vesicles at the vermilion border that rupture, crust and re-epithelialise in about seven to ten days.

Question 20Oral Pathology and Oral Medicine

A 24-year-old woman reports three episodes of painful oral ulcers in the past year. Examination shows a single 6 mm shallow ulcer with a yellow centre and erythematous halo on the buccal mucosa; earlier lesions healed within ten days without scarring. She is otherwise well. What is the most likely diagnosis?

  1. Mucous membrane pemphigoid
  2. Primary herpetic gingivostomatitis
  3. Major aphthous stomatitis
  4. Minor aphthous stomatitis Correct answer.

Explanation

Minor recurrent aphthous stomatitis produces small (under 10 mm), shallow, rounded ulcers on non-keratinized mucosa that heal within two weeks without scarring, in a patient whose general health is unaffected. The history of discrete recurrent crops fits this diagnosis exactly.

Question 21Oral Pathology and Oral Medicine

A 66-year-old woman with metastatic breast cancer has received intravenous zoledronic acid for two years. A 1 cm area of exposed necrotic bone has persisted in the posterior mandible for eleven weeks after a molar extraction. She has never received radiotherapy to the head and neck. What is the most likely diagnosis?

  1. Chronic suppurative osteomyelitis
  2. Osteoradionecrosis of the mandible
  3. Medication-related osteonecrosis of the jaw Correct answer.
  4. Periapical abscess with a draining sinus

Explanation

Exposed bone persisting for more than eight weeks in the maxillofacial region of a patient exposed to an antiresorptive agent, with no history of head and neck radiotherapy, defines medication-related osteonecrosis of the jaw. Intravenous zoledronic acid given for malignancy carries the highest risk.

Question 22Oral Pathology and Oral Medicine

Which oral mucosal lesion carries the greatest risk of malignant transformation?

  1. Erythroplakia Correct answer.
  2. Linea alba
  3. Frictional keratosis
  4. Nicotinic stomatitis

Explanation

Erythroplakia is a red patch that cannot be attributed to any other disease, and biopsy shows severe dysplasia, carcinoma in situ or invasive carcinoma in the majority of cases. Its risk of malignant transformation is higher than that of leukoplakia and far higher than reactive white lesions.

Question 23Oral Pathology and Oral Medicine

A 55-year-old woman reports persistent dry eyes and dry mouth, and both parotid glands are diffusely enlarged. The Schirmer test is abnormal and labial gland biopsy shows focal lymphocytic sialadenitis. Which serological finding is most characteristic of this disorder?

  1. Anti-smooth muscle antibodies
  2. Anti-Ro/SSA antibodies Correct answer.
  3. Anti-mitochondrial antibodies
  4. Anti-double-stranded DNA antibodies

Explanation

Keratoconjunctivitis sicca, xerostomia and focal lymphocytic sialadenitis together indicate Sjögren syndrome. Anti-Ro/SSA and anti-La/SSB antibodies are the characteristic markers, with anti-Ro/SSA present in roughly half to three-quarters of patients.

Question 24Oral Pathology and Oral Medicine

A 30-year-old man has a well-defined unilocular radiolucency surrounding the crown of an impacted mandibular third molar and attached at the cementoenamel junction. The involved tooth is vital. What is the most likely diagnosis?

  1. Dentigerous cyst Correct answer.
  2. Odontogenic keratocyst
  3. Radicular cyst
  4. Ameloblastoma

Explanation

A pericoronal radiolucency that attaches at the cementoenamel junction of an impacted tooth is the classic radiographic appearance of a dentigerous cyst, which forms by fluid accumulation between the reduced enamel epithelium and the crown. The tooth remains vital because the lesion is of developmental origin.

Question 25Oral Pathology and Oral Medicine

A 45-year-old woman has painful erosions of the gingiva and buccal mucosa with a positive Nikolsky sign. Histopathology shows suprabasal acantholysis, and direct immunofluorescence of perilesional mucosa shows intercellular deposits of IgG within the epithelium. Which diagnosis is most consistent?

  1. Linear IgA disease
  2. Mucous membrane pemphigoid
  3. Pemphigus vulgaris Correct answer.
  4. Oral lichen planus

Explanation

Suprabasal acantholysis combined with intercellular, chicken-wire deposits of IgG on direct immunofluorescence is the hallmark of pemphigus vulgaris. The autoantibodies target desmoglein 1 and 3, causing intraepithelial splitting and a positive Nikolsky sign.

Question 26Oral Pathology and Oral Medicine

A 16-year-old boy has multiple radiolucent jaw lesions consistent with odontogenic keratocysts, bifid ribs, calcification of the falx cerebri and palmar pits. Which gene is most strongly associated with this syndrome?

  1. PTCH1 gene Correct answer.
  2. APC gene
  3. MEN1 gene
  4. NF1 gene

Explanation

Multiple odontogenic keratocysts, bifid ribs, falx cerebri calcification and palmar or plantar pits define nevoid basal cell carcinoma (Gorlin-Goltz) syndrome. It is an autosomal dominant disorder caused by loss-of-function mutations in the PTCH1 tumour suppressor gene on chromosome 9q22.

Question 27Oral Pathology and Oral Medicine

A 22-year-old man is worried about multiple small, asymptomatic yellow-white spots on the buccal mucosa and upper lip. The spots are bilateral, soft, and cannot be wiped off. What is the most likely diagnosis?

  1. Koplik spots
  2. Fordyce granules Correct answer.
  3. Leukoedema
  4. Pseudomembranous candidiasis

Explanation

Fordyce granules are ectopic sebaceous glands that appear as asymptomatic yellow-white papules on the buccal mucosa, lips, and retromolar pad. They are a normal developmental variant and require no treatment. The key clinical point is that they are fixed, bilateral, and not associated with systemic illness.

Question 28Oral Pathology and Oral Medicine

A 19-year-old man with epilepsy has generalized firm gingival enlargement, worse in the anterior region, and poor plaque control. Which medication is the most likely cause?

  1. Metformin
  2. Phenytoin Correct answer.
  3. Atorvastatin
  4. Amoxicillin

Explanation

Phenytoin is a classic cause of drug-induced fibrous gingival overgrowth, and the enlargement is typically more severe when plaque control is poor. Calcium channel blockers and ciclosporin can produce a similar picture. The diagnosis is clinical, and management includes plaque control and liaison with the prescribing physician.

Question 29Oral Pathology and Oral Medicine

A 30-year-old woman reports a burning sensation on her tongue. Examination shows irregular red, depapillated patches with white borders on the dorsal tongue; the patches have changed location over several days. What is the most likely diagnosis?

  1. Oral hairy leukoplakia
  2. Pseudomembranous candidiasis
  3. Median rhomboid glossitis
  4. Geographic tongue Correct answer.

Explanation

Geographic tongue, or erythema migrans, is characterized by migrating depapillated red patches with white margins on the dorsal tongue. The diagnosis is clinical, and many patients are asymptomatic or report burning with spicy foods. The changing location is a key distinguishing feature.

Question 30Oral Pathology and Oral Medicine

A 50-year-old woman has bilateral white lacy striae on the buccal mucosa with areas of erosion. Incisional biopsy shows a dense band-like lymphocytic infiltrate at the epithelial-connective tissue interface. Which diagnosis is most consistent with these findings?

  1. Pemphigus vulgaris
  2. Oral candidiasis
  3. Oral leukoplakia
  4. Oral lichen planus Correct answer.

Explanation

Oral lichen planus classically presents with bilateral reticular white striae and a band-like lymphocytic infiltrate at the epithelial-connective tissue interface. Erosive forms can cause significant pain and require treatment, and long-standing lesions should be monitored. The bilateral distribution and histologic interface change support this diagnosis.

Question 31Oral Pathology and Oral Medicine

A 40-year-old man has an asymptomatic blue-black macule on the mandibular alveolar mucosa next to a molar with a large amalgam restoration. The lesion has been stable for several years. What is the most likely diagnosis?

  1. Kaposi sarcoma
  2. Amalgam tattoo Correct answer.
  3. Hemangioma
  4. Oral melanoma

Explanation

Amalgam tattoo results from traumatic implantation of amalgam particles into the oral mucosa and presents as a stable blue-black or gray macule adjacent to restored teeth. It is usually asymptomatic and does not change over time. Any changing or irregular pigmented lesion should still be biopsied to exclude melanoma.

Question 32Oral Pathology and Oral Medicine

A 35-year-old man reports burning mouth and progressive difficulty opening his mouth. Examination shows blanched, leathery buccal mucosa with vertical fibrous bands. He chews areca nut daily. What is the most likely diagnosis?

  1. Oral lichen planus
  2. Oral submucous fibrosis Correct answer.
  3. Scleroderma
  4. Temporomandibular joint ankylosis

Explanation

Oral submucous fibrosis results from areca nut exposure and causes progressive juxta-epithelial fibrosis, mucosal blanching, vertical fibrous bands, and restricted mouth opening. It is a potentially malignant disorder and requires habit cessation and surveillance. The combination of areca nut use, blanching, and trismus is characteristic.

Question 33Oral Pathology and Oral Medicine

A 14-year-old boy has a well-defined mixed radiolucent-radiopaque lesion in the anterior maxilla. It contains several small tooth-like structures and is preventing eruption of a canine. What is the most likely diagnosis?

  1. Cementoblastoma
  2. Compound odontoma Correct answer.
  3. Ameloblastoma
  4. Odontogenic keratocyst

Explanation

A compound odontoma contains multiple small tooth-like denticles and commonly occurs in the anterior maxilla, where it can block eruption. It is a benign odontogenic hamartoma and is treated by surgical removal. The presence of recognizable tooth-like structures within the lesion is the key radiographic clue.

Question 34Oral Pathology and Oral Medicine

A 55-year-old man has a painless, firm, sessile pink nodule on the buccal mucosa at the line of occlusion. Excisional biopsy shows dense collagenous connective tissue covered by stratified squamous epithelium. What is the most likely diagnosis?

  1. Irritation fibroma Correct answer.
  2. Lipoma
  3. Pyogenic granuloma
  4. Mucocele

Explanation

Irritation fibroma is a reactive fibrous hyperplasia caused by chronic mechanical trauma and commonly occurs at the occlusal line. Histologically it consists of dense collagenous connective tissue covered by stratified squamous epithelium. Simple excision is curative once the source of trauma is removed.

Question 35Oral Pathology and Oral Medicine

A 25-year-old woman has a slowly enlarging mandibular swelling. A radiograph shows a multilocular radiolucency with fine, wispy trabeculae described as a tennis-racket pattern. Which is the most likely diagnosis?

  1. Ameloblastoma
  2. Odontogenic myxoma Correct answer.
  3. Odontogenic keratocyst
  4. Central giant cell granuloma

Explanation

Odontogenic myxoma often produces fine straight or wispy septa described as a tennis-racket or stepladder pattern. It is a locally infiltrative benign tumor, so complete removal with adequate margins is important. The radiographic pattern and slow expansion support this diagnosis.

Question 36Oral Pathology and Oral Medicine

A 38-year-old man has asymptomatic corrugated white plaques on the lateral border of the tongue that cannot be wiped off. He is HIV-positive with a low CD4 count. What is the most likely diagnosis?

  1. Frictional keratosis
  2. Pseudomembranous candidiasis
  3. Squamous cell carcinoma
  4. Oral hairy leukoplakia Correct answer.

Explanation

Oral hairy leukoplakia is caused by Epstein-Barr virus and presents as corrugated white plaques on the lateral tongue in HIV infection and other immunosuppressed states. The lesions are fixed and cannot be wiped off. Diagnosis is usually clinical, and biopsy is reserved for atypical cases.

Question 37Restorative and Operative Dentistry

According to G.V. Black's classification, a carious lesion on the mesial surface of a maxillary central incisor that does not involve the incisal angle is classified as which cavity?

  1. Class III Correct answer.
  2. Class IV
  3. Class V
  4. Class II

Explanation

Class III cavities involve the proximal surfaces of anterior teeth without involvement of the incisal angle. Class II lesions are proximal cavities in posterior teeth, while Class IV includes the incisal angle. Class V is located in the gingival third of the facial or lingual surface.

Question 38Restorative and Operative Dentistry

Which phosphoric acid concentration is most commonly recommended for etching enamel before placement of an adhesive restoration?

  1. 37% Correct answer.
  2. 10%
  3. 50%
  4. 5%

Explanation

Enamel is typically etched with 30% to 40% phosphoric acid, with 37% being the standard concentration, usually applied for about 15 seconds. This produces a microporous surface that allows resin tags to form. Stronger concentrations can precipitate monocalcium phosphate and reduce the etch pattern.

Question 39Restorative and Operative Dentistry

Which isolation method is considered the standard for moisture control during placement of a posterior adhesive restoration?

  1. Gingival retraction cord
  2. Cotton rolls alone
  3. Saliva ejector alone
  4. Rubber dam isolation Correct answer.

Explanation

Rubber dam isolation provides a dry, clean field and protects the patient from swallowed or aspirated materials, so it is the standard for adhesive dentistry. Cotton rolls and saliva ejectors do not prevent moisture contamination from gingival fluid or the tongue. Retraction cord is used for impression-making, not for operative field isolation.

Question 40Restorative and Operative Dentistry

When a total-etch adhesive bonds to dentin, what structure is formed by resin infiltration into demineralized collagen?

  1. Hybrid layer Correct answer.
  2. Smear layer
  3. Decalcification zone
  4. Enamel tags

Explanation

After acid etching and rinsing, the adhesive resin penetrates the exposed collagen network and polymerizes, creating a hybrid layer of resin-infiltrated dentin. This layer is the main mechanism of micromechanical retention to dentin. Enamel tags form in etched enamel, not in dentin.

Question 41Restorative and Operative Dentistry

Why is selective etching of enamel with phosphoric acid recommended before applying a self-etch adhesive?

  1. It lowers the adhesive pH to enhance collagen infiltration.
  2. It improves enamel bonding without over-etching dentin. Correct answer.
  3. It eliminates the need for light curing.
  4. It completely removes the smear layer from dentin.

Explanation

Self-etch adhesives bond less durably to unetched enamel than to etched enamel, so selective phosphoric acid etching of enamel margins improves the enamel bond. Because the acid is confined to enamel, excessive dentin demineralization is avoided. The adhesive itself still modifies the smear layer and requires light curing.

Question 42Restorative and Operative Dentistry

A Class I composite restoration has a high configuration factor (C-factor). What is the main clinical consequence?

  1. Greater polymerization shrinkage stress at bonded walls Correct answer.
  2. Reduced depth of cure at the pulp
  3. Lower wear resistance
  4. Increased fluoride release

Explanation

C-factor is the ratio of bonded to unbonded surface area. A Class I cavity bonds on five walls, so shrinkage during polymerization cannot be relieved by flow from a free surface, producing high stress that may cause debonding, cuspal deflection, or marginal gaps. Incremental placement is used to reduce this stress.

Question 43Restorative and Operative Dentistry

Which matrix system is preferred for restoring a Class II composite with a proximal box that extends to the gingival margin?

  1. Clear plastic strip
  2. Tofflemire metal matrix band
  3. Sectional matrix with a separation ring Correct answer.
  4. Celluloid matrix without a ring

Explanation

A sectional matrix with a separation ring adapts closely to the gingival margin, separates the teeth to compensate for band thickness, and helps create a tight proximal contact and anatomic contour. A circumferential Tofflemire band tends to leave a flat proximal contour and a weak contact. Clear strips and unsupported celluloid matrices cannot reliably establish proximal form.

Question 44Restorative and Operative Dentistry

A patient returns one week after placement of a Class II composite restoration with pain on biting; the radiograph shows no overhang or recurrent caries. Which cause should be evaluated first?

  1. Marginal leakage from an absent enamel bevel
  2. Pulpal necrosis
  3. Occlusal interference on the restoration Correct answer.
  4. Delayed hypersensitivity to the adhesive

Explanation

Pain elicited specifically by biting on a recently placed restoration most often indicates a premature occlusal contact, so the occlusion should be checked and adjusted first. Sharp biting pain is a mechanical symptom rather than a sign of pulpal necrosis. Marginal leakage and hypersensitivity usually cause thermal or spontaneous sensitivity rather than pain localized to biting.

Question 45Restorative and Operative Dentistry

Which statement best describes the clinical action of 38% silver diamine fluoride (SDF) on an active carious lesion?

  1. It arrests the lesion and darkens demineralized tissue. Correct answer.
  2. It is applied only to sound enamel to prevent caries.
  3. It has no caries-arresting effect on dentin lesions.
  4. It permanently eliminates the need for restorative treatment.

Explanation

Silver diamine fluoride arrests active caries through the combined effects of silver, which has antimicrobial action, and fluoride, which promotes remineralization. It characteristically stains demineralized carious tissue black, which is an aesthetic limitation. It does not replace restorative care when a cavity requires function or aesthetics to be restored.

Question 46Restorative and Operative Dentistry

During caries excavation in a permanent molar, which layer of carious dentin should be left at the cavity floor because it can remineralize after sealing?

  1. Infected dentin
  2. Affected dentin Correct answer.
  3. Smear layer
  4. Tertiary dentin

Explanation

Affected dentin is softened and demineralized but not yet invaded by bacteria, and it retains a collagen scaffold that can remineralize once sealed from the oral environment. Infected dentin is bacterially contaminated and must be removed. Leaving affected dentin conserves tooth structure and reduces the risk of pulp exposure.

Question 47Restorative and Operative Dentistry

During trituration of dental amalgam, what is the primary function of mercury?

  1. To increase the final compressive strength of the set restoration
  2. To dissolve the alloy particles and form a plastic mass that sets Correct answer.
  3. To reduce the thermal conductivity of the restoration
  4. To sterilize the alloy powder before condensation

Explanation

Mercury is a liquid metal that alloys with the silver-tin-copper powder, producing a pliable mass that can be condensed and then hardens. It does not sterilize the powder, and the final strength and thermal conductivity depend on the set phases and porosity rather than on mercury acting alone.

Question 48Restorative and Operative Dentistry

Which restorative material is selected primarily for its ability to release fluoride over time and inhibit secondary caries at the restoration margin?

  1. Flowable composite resin
  2. Conventional glass ionomer cement Correct answer.
  3. Microfilled composite resin
  4. Zinc phosphate cement

Explanation

Conventional glass ionomer cement releases fluoride and can take up fluoride again from topical sources, which helps inhibit secondary caries at margins. Composite resins and zinc phosphate cement do not provide this sustained fluoride release.

Question 49Restorative and Operative Dentistry

For a conventional light-cured composite resin, what is the maximum recommended increment thickness to ensure adequate polymerization at the cavity floor?

  1. 0.5 mm
  2. 2 mm Correct answer.
  3. 4 mm
  4. 1 mm

Explanation

Light intensity decreases as it passes through composite, so conventional composites are usually placed in increments of about 2 mm or less to ensure adequate conversion at the base. Thicker increments can leave uncured or undercured resin at the cavity floor.

Question 50Restorative and Operative Dentistry

After etching dentin with phosphoric acid in an etch-and-rinse adhesive system, why should the dentin surface remain visibly moist before applying the primer?

  1. Moisture prevents the collapse of the demineralized collagen network Correct answer.
  2. Moisture increases the thickness of the hybrid layer by dissolving the smear layer
  3. Moisture accelerates the polymerization of the adhesive monomer
  4. Moisture neutralizes the residual phosphoric acid on the dentin surface

Explanation

Etching removes hydroxyapatite and leaves a exposed collagen mesh; if the dentin dries, the collagen collapses and resin cannot infiltrate properly. Keeping the surface moist maintains the expanded collagen network so the primer can penetrate and form a sound hybrid layer.