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DBT-BET practice questions

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Question 1Dental Anatomy and Morphology

Which permanent tooth typically has the smallest crown in the human dentition?

  1. Maxillary lateral incisor
  2. Mandibular lateral incisor
  3. Maxillary central incisor
  4. Mandibular central incisor Correct answer.

Explanation

The mandibular central incisor is generally regarded as the smallest tooth in the permanent dentition, with the narrowest mesiodistal crown dimension. Its labial and lingual surfaces are nearly flat and its incisal edge is straight. The mandibular lateral incisor is slightly larger and more asymmetrical.

Question 2Dental Anatomy and Morphology

How many cusps does a typical permanent maxillary first molar have?

  1. Five Correct answer.
  2. Three
  3. Six
  4. Four

Explanation

The maxillary first molar normally has five cusps: mesiobuccal, distobuccal, mesiolingual, distolingual, and the cusp of Carabelli on the mesiolingual surface. This five-cusp pattern distinguishes it from the maxillary second molar, which usually has four.

Question 3Dental Anatomy and Morphology

Which permanent tooth usually possesses the longest root in the human dentition?

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

Explanation

The maxillary canine has the longest root of any permanent tooth, often exceeding the crown length considerably. This long root provides firm anchorage in the maxilla. The mandibular canine root is also long but generally shorter.

Question 4Dental Anatomy and Morphology

The cusp of Carabelli is most characteristically found on which tooth?

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

Explanation

The cusp of Carabelli is an accessory cusp located on the mesiolingual surface of the maxillary first molar. It is a variable trait, more common in some populations. No other permanent tooth carries this named structure as typically.

Question 5Dental Anatomy and Morphology

Which tooth type is the only one in the permanent dentition that normally has no predecessor in the primary dentition?

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

Explanation

The permanent first molars erupt distal to the primary second molars and are not preceded by any primary tooth. All incisors, canines, and premolars replace primary teeth. This makes the first molar a key occlusal landmark.

Question 6Dental Anatomy and Morphology

A permanent maxillary lateral incisor with a small accessory cusp on its cingulum is best described as which anomaly?

  1. Dens invaginatus
  2. Microdontia
  3. Dens evaginatus
  4. Talon cusp Correct answer.

Explanation

A talon cusp is an accessory cusp-like projection arising from the cingulum or lingual surface of an anterior tooth, most often the maxillary lateral incisor. It is a developmental shape anomaly distinct from invagination or evagination of the root.

Question 7Dental Anatomy and Morphology

Which premolar most commonly has three cusps and a Y-shaped occlusal groove pattern?

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

Explanation

The mandibular second premolar frequently has three cusps (one buccal, two lingual) with a Y-shaped central groove pattern. The two-cusp form with a U-shaped groove also occurs. The maxillary premolars and mandibular first premolar do not show this three-cusp pattern.

Question 8Dental Anatomy and Morphology

Which primary tooth most closely resembles its permanent successor in crown form?

  1. Primary maxillary first molar
  2. Primary maxillary central incisor Correct answer.
  3. Primary mandibular first molar
  4. Primary mandibular second molar

Explanation

The primary incisors closely resemble their permanent successors in general crown form, differing mainly in size and proportions. The primary molars, by contrast, have a distinctive form unlike the premolars that replace them.

Question 9Dental Anatomy and Morphology

In a permanent mandibular first molar, how many roots and canals are typically present?

  1. One root with one canal
  2. Two roots with three canals Correct answer.
  3. Three roots with four canals
  4. Two roots with two canals

Explanation

The mandibular first molar typically has two roots (mesial and distal) but three canals: two in the mesial root and one in the distal root. The distal root occasionally has a second canal. This configuration is a common endodontic consideration.

Question 10Dental Anatomy and Morphology

Which surface feature is most characteristic of the lingual aspect of a permanent maxillary central incisor?

  1. A pronounced distal accessory cusp
  2. A well-developed cingulum with marginal ridges Correct answer.
  3. A prominent, deeply forked lingual groove
  4. A completely flat lingual surface with no ridges

Explanation

The maxillary central incisor has a well-developed cingulum and distinct mesial and distal marginal ridges on its lingual surface, forming a shallow lingual fossa. This anatomy is more pronounced than in the mandibular incisors.

Question 11Dental Anatomy and Morphology

A clinician notes that a permanent maxillary first premolar has two roots. What is the most common canal configuration in this tooth?

  1. Two canals, one in each root Correct answer.
  2. One canal in each of three roots
  3. Three canals in two roots
  4. One canal in a single root

Explanation

The maxillary first premolar most often has two roots (buccal and lingual) with one canal in each, giving two canals. A single-rooted variant with two canals also occurs. Three canals are uncommon.

Question 12Dental Anatomy and Morphology

Which statement correctly describes the curvature of the mesial root of a permanent mandibular first molar?

  1. It typically curves buccally along its entire length.
  2. It typically curves mesially in its apical third.
  3. It typically curves distally in its apical third. Correct answer.
  4. It is typically straight with no curvature.

Explanation

The mesial root of the mandibular first molar commonly shows a distal curvature in its apical portion, which is relevant during canal negotiation. This curvature must be respected to avoid ledging or transportation.

Question 13Dental Anatomy and Morphology

Which permanent tooth has a crown whose mesial incisal angle is sharper and whose distal incisal angle is more rounded?

  1. Mandibular central incisor
  2. Mandibular lateral incisor
  3. Maxillary canine
  4. Maxillary central incisor Correct answer.

Explanation

The maxillary central incisor shows a relatively sharp mesioincisal angle and a more rounded distoincisal angle, a classic asymmetry used for orientation. This contrast is less pronounced in the mandibular incisors.

Question 14Dental Anatomy and Morphology

The oblique ridge is a prominent feature of which permanent tooth?

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

Explanation

The oblique ridge runs from the mesiolingual cusp to the distobuccal cusp on the occlusal surface of the maxillary first molar. It is a defining anatomical landmark of that tooth. Mandibular molars do not possess an oblique ridge.

Question 15Dental Anatomy and Morphology

Which primary molar most closely resembles the permanent maxillary first molar in crown form?

  1. Primary mandibular first molar
  2. Primary maxillary first molar
  3. Primary maxillary second molar Correct answer.
  4. Primary mandibular second molar

Explanation

The primary maxillary second molar resembles the permanent maxillary first molar in overall form, which is why it is sometimes called the 'first molar of the primary dentition.' The primary first molars have no permanent analogue.

Question 16Dental Anatomy and Morphology

In the FDI two-digit system, which tooth is designated as 36?

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

Explanation

In the FDI system, the first digit indicates the quadrant and the second the tooth position. Quadrant 3 is the mandibular left, and tooth 6 is the first molar, so 36 is the mandibular left first molar.

Question 17Dental Anatomy and Morphology

Which feature distinguishes the permanent maxillary canine from the permanent mandibular canine?

  1. The mandibular canine is wider mesiodistally.
  2. The maxillary canine lacks a cusp tip.
  3. The mandibular canine has a more prominent cingulum.
  4. The maxillary canine has a more prominent cingulum and lingual ridge. Correct answer.

Explanation

The maxillary canine typically has a more prominent cingulum, lingual ridge, and marginal ridges than the mandibular canine. The mandibular canine is narrower mesiodistally and has a less pronounced lingual anatomy.

Question 18Dental Anatomy and Morphology

Which of the following best explains why the primary molars show less occlusal wear resistance relative to their enamel thickness?

  1. Primary molars lack dentin beneath the enamel.
  2. Primary molars have thicker enamel than permanent molars.
  3. Primary molars have thinner enamel with more constant thickness over the cusps. Correct answer.
  4. Primary molars have no pulp chamber.

Explanation

Primary teeth have thinner enamel and dentin than permanent teeth, and the enamel is more uniformly thin over the cusps rather than thickening as in permanent molars. This contributes to faster wear and caries progression. It also influences cavity preparation design in pediatric dentistry.

Question 19Dental Anatomy and Morphology

Which morphological feature is shared by the permanent maxillary second premolar and the maxillary first premolar?

  1. Both lack a lingual cusp.
  2. Both typically have two cusps with a mesiodistal central groove. Correct answer.
  3. Both have three cusps.
  4. Both typically have two roots.

Explanation

Both maxillary premolars typically have two cusps (buccal and lingual) with a central groove running mesiodistally. The maxillary second premolar, however, is usually single-rooted, whereas the first premolar often has two roots.

Question 20Dental Anatomy and Morphology

Which permanent tooth most frequently shows a distolingual groove that can predispose to periodontal involvement?

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

Explanation

The maxillary lateral incisor often exhibits a distolingual groove extending from the cingulum onto the root, which can harbor plaque and contribute to localized periodontal problems. This groove is a recognized anatomical feature of that tooth.

Question 21Dental Anatomy and Morphology

Which statement about the pulp chamber of a young permanent molar is most accurate?

  1. It is absent until root completion.
  2. It is large with pulp horns extending toward the cusps. Correct answer.
  3. It is confined to the mesial root.
  4. It is small and located entirely in the root.

Explanation

In young permanent molars, the pulp chamber is relatively large and pulp horns project toward the cusps, reflecting incomplete secondary dentin deposition. With age, the chamber recedes and the horns flatten. This anatomy affects cavity preparation and endodontic access.

Question 22Dental Anatomy and Morphology

Which tooth typically shows the greatest mesiodistal crown dimension among the permanent teeth?

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

Explanation

The maxillary first molar generally has the greatest mesiodistal crown width of all permanent teeth, contributing to its role as the keystone of the arch. Its broad occlusal table accommodates five cusps.

Question 23Dental Anatomy and Morphology

Which primary tooth is most likely to be mistaken for a permanent premolar because of its molar-like form?

  1. Primary maxillary first molar
  2. Primary mandibular second molar Correct answer.
  3. Primary mandibular canine
  4. Primary maxillary central incisor

Explanation

The primary mandibular second molar has a molariform crown resembling the permanent mandibular first molar, but its position and size can lead to confusion during mixed-dentition assessment. Careful attention to the primary dentition pattern avoids misidentification.

Question 24Dental Anatomy and Morphology

What is the significance of the mamelons on a newly erupted permanent incisor?

  1. They are rounded incisal ridges formed by three labial lobes. Correct answer.
  2. They indicate a developmental defect requiring treatment.
  3. They are carious lesions at the incisal edge.
  4. They are remnants of the primary tooth root.

Explanation

Mamelons are rounded protuberances on the incisal edge of newly erupted incisors, formed by the three labial developmental lobes. They typically wear away with normal function. Their presence can help confirm recent eruption.

Question 25Dental Anatomy and Morphology

Which of the following correctly pairs a permanent tooth with its typical number of cusps?

  1. Mandibular first molar - four cusps
  2. Maxillary second molar - three cusps
  3. Maxillary first premolar - two cusps Correct answer.
  4. Mandibular second premolar - two cusps only

Explanation

The maxillary first premolar typically has two cusps, a larger buccal and a smaller lingual. The other pairings misstate the usual cusp counts for those teeth.

Question 26Dental Anatomy and Morphology

Which permanent tooth normally has a crown in which the mesial marginal ridge is longer and more prominent than the distal marginal ridge on the lingual surface?

  1. Permanent maxillary second premolar
  2. Permanent mandibular first premolar Correct answer.
  3. Permanent maxillary first premolar
  4. Permanent mandibular second premolar

Explanation

On the permanent mandibular first premolar the lingual cusp is small and tipped mesially, and the mesial marginal ridge is longer and more prominent than the distal one. This asymmetry reflects the mesially inclined lingual cusp and helps distinguish it from the mandibular second premolar, whose lingual cusp is larger and more symmetric.

Question 27Dental Anatomy and Morphology

A permanent mandibular lateral incisor is compared with a permanent mandibular central incisor. Which feature best distinguishes the lateral incisor?

  1. The cingulum is absent on the lingual surface
  2. The incisal edge slopes cervically toward the distal and the crown is wider mesiodistally Correct answer.
  3. The root is shorter and more rounded in cross-section
  4. The crown is narrower mesiodistally and nearly symmetric about the long axis

Explanation

The mandibular lateral incisor is wider mesiodistally than the central and its incisal edge slopes cervically toward the distal because the distal contact is more cervical. The central incisor is the more symmetric tooth with a nearly horizontal incisal edge.

Question 28Dental Anatomy and Morphology

A permanent maxillary first molar has a root that is described as the largest and most divergent of the three roots. Which root is this?

  1. The distolingual root
  2. The palatal root Correct answer.
  3. The mesiobuccal root
  4. The distobuccal root

Explanation

The palatal root of the maxillary first molar is the largest and most divergent root, and it is typically curved buccally in its apical third. The two buccal roots are smaller, with the mesiobuccal root being broader and often showing two canals.

Question 29Dental Anatomy and Morphology

A clinician examines a permanent maxillary canine and notes a prominent ridge running from the cingulum to the incisal edge on the lingual surface. What is this ridge called?

  1. The cusp ridge
  2. The mesial marginal ridge
  3. The cervical ridge
  4. The lingual ridge Correct answer.

Explanation

The lingual ridge of the maxillary canine extends from the cingulum to the incisal edge and separates the mesial and distal lingual fossae. It is a characteristic feature that gives the canine its bulky lingual contour.

Question 30Dental Anatomy and Morphology

A permanent maxillary second molar is compared with a permanent maxillary first molar. Which morphological difference is most characteristic of the second molar?

  1. The crown is larger and has a more prominent distolingual cusp
  2. The oblique ridge is consistently absent
  3. The mesiobuccal root consistently contains three canals
  4. The distolingual cusp is reduced or absent and the roots are more often fused Correct answer.

Explanation

The maxillary second molar tends to be smaller than the first, with a reduced or absent distolingual cusp (giving a more rhomboid or heart-shaped outline) and roots that are closer together or fused. These features help distinguish it from the larger, more cusped first molar.

Question 31Dental Materials Science

Which property of dental amalgam is primarily responsible for its long-term clinical success as a posterior restorative material?

  1. Low modulus of elasticity
  2. High tensile strength
  3. High compressive strength Correct answer.
  4. High thermal diffusivity

Explanation

Set amalgam is strong in compression, which matches the predominantly compressive occlusal loading it receives, and this strength is retained over many years. Its tensile and flexural strengths are comparatively modest, so it is not used where bending loads dominate.

Question 32Dental Materials Science

During setting, dental gypsum products undergo which dimensional change?

  1. Alternating expansion and contraction
  2. No change
  3. Contraction
  4. Expansion Correct answer.

Explanation

The conversion of calcium sulfate hemihydrate to dihydrate involves crystal growth that produces a net setting expansion. This expansion is small but clinically relevant because it can affect the fit of casts.

Question 33Dental Materials Science

Which monomer is the principal liquid component of conventional unfilled acrylic denture base resin?

  1. Methyl methacrylate Correct answer.
  2. Ethyl methacrylate
  3. Bis-GMA
  4. Urethane dimethacrylate

Explanation

Conventional heat-cured denture base material is a poly(methyl methacrylate) system formed from methyl methacrylate monomer polymerized around prepolymerized PMMA powder. Bis-GMA and urethane dimethacrylate belong to composite resin chemistry.

Question 34Dental Materials Science

What is the main function of the filler particles in a dental composite resin?

  1. Increase water sorption
  2. Increase thermal expansion
  3. Increase the amount of free monomer
  4. Increase strength and reduce polymerization shrinkage Correct answer.

Explanation

Inorganic filler raises strength, stiffness, and wear resistance while reducing the resin fraction that shrinks on polymerization. It also lowers thermal expansion and water sorption rather than raising them.

Question 35Dental Materials Science

Which impression material is an aqueous hydrocolloid that must be kept moist after removal from the mouth?

  1. Polysulfide
  2. Polyether
  3. Addition silicone
  4. Reversible hydrocolloid (agar) Correct answer.

Explanation

Agar is a reversible hydrocolloid whose water content makes it susceptible to syneresis and imbibition, so it must be stored in a humid environment. The elastomers listed are hydrophobic or only mildly hydrophilic and do not require wet storage.

Question 36Dental Materials Science

What is the principal role of eugenol in zinc oxide-eugenol cement?

  1. It acts as an inert filler
  2. It reacts with zinc oxide to form a chelate matrix Correct answer.
  3. It accelerates setting by absorbing water
  4. It provides fluoride release

Explanation

Eugenol chelates with zinc ions from the zinc oxide powder to form a zinc eugenolate matrix that sets the cement. Its additional analgesic effect on pulp is a separate clinical property, not the setting mechanism.

Question 37Dental Materials Science

Which type of dental wax is used to form the pattern for a metal casting?

  1. Bite registration wax
  2. Boxing wax
  3. Inlay casting wax Correct answer.
  4. Sticky wax

Explanation

Inlay casting wax is formulated to be carved and to burn out cleanly, leaving minimal residue in the mold. Bite registration, boxing, and sticky waxes serve other laboratory purposes.

Question 38Dental Materials Science

What does the term 'noble' indicate about a dental casting alloy?

  1. It is used only for porcelain-fused-to-metal restorations
  2. It contains a high proportion of gold and platinum-group metals Correct answer.
  3. It has a high yield strength
  4. It is free of base metals by definition

Explanation

Noble status refers to the content of gold and the platinum-group elements, which resist corrosion and oxidation. High strength and freedom from base metals are not defining criteria.

Question 39Dental Materials Science

A clinician polymerizes a light-cured composite in increments that are too thick. Which outcome is most directly expected?

  1. Increased filler content at the base
  2. Reduced depth of cure with higher residual monomer at the base Correct answer.
  3. Reduced polymerization shrinkage at the surface
  4. Improved color stability

Explanation

Light intensity attenuates with depth, so thick increments leave the deepest resin undercured, with more unreacted monomer and weaker mechanical properties. Incremental placement of limited thickness is used to avoid this.

Question 40Dental Materials Science

A cast post-and-core is to be cemented into a prepared root canal. Which luting agent characteristic is most important for retention in this situation?

  1. High solubility in oral fluids
  2. High compressive strength and low film thickness Correct answer.
  3. Long working time with no setting reaction
  4. High thermal expansion

Explanation

A luting agent must flow into a thin film to seat the restoration while withstanding functional loads, so adequate strength combined with low film thickness is essential. High solubility would cause gradual loss of the cement and failure.

Question 41Dental Materials Science

Why is a separating medium applied to the mold before packing denture base resin?

  1. To accelerate polymerization of the resin
  2. To increase the translucency of the denture base
  3. To sterilize the mold surface
  4. To prevent the acrylic from bonding to the gypsum mold Correct answer.

Explanation

The monomer can penetrate and bond to the investing stone, so an alginate or similar separating medium creates a barrier that allows clean separation of the processed denture. It has no role in curing speed, optics, or sterilization.

Question 42Dental Materials Science

An addition silicone impression is poured after a delay of several days without proper storage. What is the most likely consequence?

  1. Increased tear strength of the set material
  2. Improved dimensional accuracy
  3. Spontaneous conversion to a polyether
  4. Distortion from continued polymerization and stress relaxation Correct answer.

Explanation

Addition silicones continue to polymerize and release hydrogen gas, and stored impressions can undergo stress relaxation and distortion if pouring is delayed. Prompt pouring, or storage according to the manufacturer's instructions, minimizes this.

Question 43Dental Materials Science

Which mechanism best explains the anticariogenic effect of fluoride released from a glass ionomer restoration?

  1. Fluoride neutralizes all oral acids permanently
  2. Fluoride increases the compressive strength of enamel
  3. Fluoride kills all cariogenic bacteria on contact
  4. Fluoride promotes remineralization and inhibits demineralization of adjacent enamel Correct answer.

Explanation

Released fluoride participates in remineralization and forms fluorapatite, which is more acid resistant, thereby reducing demineralization at the restoration margin. It does not permanently neutralize acids or sterilize the oral cavity.

Question 44Dental Materials Science

A patient reports sharp pain when a metallic restoration contacts a silver spoon. Which property of the restoration is most relevant?

  1. Galvanic current generated between dissimilar metals Correct answer.
  2. Compressive strength
  3. Coefficient of thermal expansion
  4. Thermal conductivity of the metal

Explanation

Two dissimilar metals in an electrolyte, such as saliva, form a galvanic cell that produces a current and can cause sharp pain. The phenomenon requires a second metal and an electrolyte, not merely a single metallic restoration.

Question 45Dental Materials Science

Which factor most increases the setting expansion of a dental stone if uncontrolled?

  1. Longer mixing time with distilled water only
  2. Increased water-to-powder ratio
  3. Decreased water-to-powder ratio Correct answer.
  4. Use of a plastic mixing bowl

Explanation

A thicker mix, meaning less water relative to powder, produces more crystal interlocking and greater setting expansion. Manufacturers specify the water-to-powder ratio to control both expansion and strength.

Question 46Dental Materials Science

Which property of polyether impression material distinguishes it from addition silicone?

  1. Greater hydrophilicity and higher stiffness after setting Correct answer.
  2. Requires wet storage
  3. Lower dimensional stability
  4. Cannot be used in a stock tray

Explanation

Polyether is more hydrophilic than addition silicone, which helps in a wet field, but it is also stiffer and less dimensionally stable over long storage. Addition silicone is generally more stable and less rigid.

Question 47Dental Materials Science

Which statement about the polymerization shrinkage of a dental composite is most accurate?

  1. Shrinkage is unrelated to the monomer system
  2. Shrinkage is eliminated by adding more filler
  3. Shrinkage is proportional to the volume of resin matrix and can produce marginal stress Correct answer.
  4. Shrinkage occurs only in unfilled resins

Explanation

Shrinkage arises from the conversion of monomer to polymer, so reducing the resin fraction and using incremental placement limits it. The resulting stress at the bonded interface can cause marginal gaps or cuspal deflection.

Question 48Dental Materials Science

A zinc phosphate cement is mixed on a cool glass slab. What is the main purpose of cooling the slab?

  1. To increase the final compressive strength beyond specification
  2. To sterilize the mixing surface
  3. To prevent the powder from dissolving
  4. To prolong working time by slowing the exothermic setting reaction Correct answer.

Explanation

The setting reaction is exothermic, and a cool slab dissipates heat, extending working time so the cement can be mixed and seated properly. The slab is not a sterilizing device and does not change solubility.

Question 49Dental Materials Science

Which characteristic makes a resin-modified glass ionomer attractive for a Class V restoration in a patient with limited moisture control?

  1. It has no setting reaction until light-cured
  2. It sets partly by an acid-base reaction and tolerates moisture while releasing fluoride Correct answer.
  3. It contains no resin component
  4. It requires complete isolation and desiccation

Explanation

Resin-modified glass ionomer combines an acid-base reaction with light-activated resin polymerization, giving early resistance to moisture plus fluoride release and chemical bonding. It is therefore more forgiving than a purely resin composite in a wet field.

Question 50Dental Materials Science

Which property of titanium makes it suitable for dental implants?

  1. Formation of a stable passive oxide layer that promotes osseointegration Correct answer.
  2. High thermal conductivity
  3. High solubility in saliva
  4. Very low elastic modulus compared with bone

Explanation

Titanium spontaneously forms a thin, stable titanium dioxide layer that resists corrosion and supports bone apposition. Its modulus is closer to bone than some metals but not lower than bone, and it is not soluble in saliva.