NEET-PG 2012 — Dental
9 Previous Year Questions with Answers & Explanations
Stability of alveoli is maintained by:
What is the forensic method of identification that utilizes lip prints?
Brutonian lines on gums are seen in poisoning with which of the following substances?
What percentage of oral cancer cases is attributed to tobacco use?
What is the first permanent tooth to erupt?
Which of the following conditions is NOT associated with delayed dentition?
Epulis arises from -
Kennedy phenomenon is seen in:
The primary indication for enucleation in pediatric patients is:
NEET-PG 2012 - Dental NEET-PG Practice Questions and MCQs
Question 1: Stability of alveoli is maintained by:
- A. Negative intrapleural pressure
- B. Residual air in alveoli
- C. Compliance of the lungs
- D. Reduced surface tension by surfactant (Correct Answer)
Explanation: ***Reduced surface tension by surfactant*** - **Surfactant** (a mixture of lipoproteins) reduces the **surface tension** at the air-liquid interface within the alveoli, preventing their collapse at the end of expiration. - This reduction in surface tension helps to maintain the **stability** and patency of the smaller alveoli, preventing them from emptying into larger ones. *Compliance of the lungs* - **Compliance** refers to the distensibility of the lungs and chest wall, indicating how easily they can be stretched. - While pulmonary compliance is important for easy breathing, it does not directly maintain the stability of individual alveoli in preventing their collapse. *Negative intrapleural pressure* - **Negative intrapleural pressure** helps to keep the lungs expanded by creating a vacuum between the visceral and parietal pleura, pulling the lungs outwards. - This pressure prevents the lung as a whole from collapsing but does not directly prevent the collapse of individual alveoli due to surface tension. *Residual air in alveoli* - **Residual volume** is the amount of air remaining in the lungs after a maximal exhalation. - While residual air prevents the complete collapse of the lungs, it is surface tension reduction by surfactant that specifically maintains the stability of individual alveoli against collapse forces.
Question 2: What is the forensic method of identification that utilizes lip prints?
- A. Trichology
- B. Dactylography
- C. Poroscopy
- D. Cheiloscopy (Correct Answer)
Explanation: ***Cheiloscopy*** - **Cheiloscopy** is the scientific study of lip prints for human identification, based on the unique patterns of furrows on the human lips. - These patterns are considered individual and permanent, making them useful in forensic investigations. *Dactylography* - **Dactylography** is the study of fingerprints, which involves analyzing the unique patterns of ridges and furrows on the fingertips for identification. - It is one of the most widely used and reliable methods for personal identification in forensic science, but does not involve lip prints, *Poroscopy* - **Poroscopy** is a forensic technique that involves the examination of the pores on the ridges of fingerprints. - It is used to individualize fingerprints when there is insufficient ridge detail, but it focuses on pores, not lip prints. *Trichology* - **Trichology** is the scientific study of hair and scalp. - In forensics, it involves analyzing hair samples to determine characteristics such as origin, race, and presence of toxins, but not lip prints.
Question 3: Brutonian lines on gums are seen in poisoning with which of the following substances?
- A. Lead (Correct Answer)
- B. Mercury
- C. Zinc
- D. Arsenic
Explanation: ***Lead*** - **Brutonian lines**, also known as **Burton's lines**, are a classic sign of chronic lead poisoning, appearing as a blue or blue-black line along the gum margin. - This discoloration is caused by the reaction of circulating lead with sulfur ions released by oral bacteria, forming lead sulfide deposits in the gingival tissue. *Mercury* - Mercury poisoning can cause **gingivitis**, **stomatitis**, and excessive salivation, but typically not the distinct Burton's lines. - A characteristic feature of chronic mercury poisoning is often **erected tremor** and **erethism** (changes in mood and irritability). *Arsenic* - Chronic arsenic poisoning can lead to **hyperkeratosis** and **hyperpigmentation** of the skin (rain drop pigmentation), as well as **peripheral neuropathy**. - It does not typically cause the specific gingival discoloration seen in lead poisoning. *Zinc* - Zinc intoxication is relatively rare and often results from excessive ingestion of zinc-containing supplements or industrial exposure. - Symptoms usually include **nausea, vomiting, diarrhea**, and sometimes **copper deficiency**, but not gum line discoloration.
Question 4: What percentage of oral cancer cases is attributed to tobacco use?
- A. 60% of cases
- B. 10% of cases
- C. 40% of cases
- D. 70% of cases (Correct Answer)
Explanation: ***90%*** - Nicotine is a significant contributor to **oral cancer**, with studies indicating it is responsible for about **90%** of cases [1]. - Its carcinogenic effects are amplified when combined with other risk factors such as **tobacco** and **alcohol** use [1]. *40%* - This percentage underestimates nicotine's role in oral cancer development, which is much higher. - Key studies suggest that the impact of nicotine alone is much greater than **40%**, highlighting its pivotal role in carcinogenesis. *60%* - This estimate also falls short, as the consensus in oncology is that nicotine significantly contributes even beyond **60%**. - Oral cancer risk is further elevated when nicotine is consumed in conjunction with other **carcinogens** [1], rather than just being limited to a single contribution. *10%* - This figure drastically underrepresents nicotine's involvement, as it is a major causative agent in oral cancer. - The **10%** suggestion implies minimal risk, contradicting clinical evidence that strongly supports a far greater role for nicotine. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 738-739.
Question 5: What is the first permanent tooth to erupt?
- A. First premolar
- B. Second premolar
- C. First molar (Correct Answer)
- D. Second molar
Explanation: ***First molar*** - The **first molars** are typically the first permanent teeth to erupt, usually around **6 years of age**. - They erupt distal to the primary second molars and are not preceded by primary teeth, making them crucial for establishing the **occlusion**. *First premolar* - **First premolars** typically erupt later, between **10 and 11 years of age**, replacing the primary first molars. - Their eruption is part of the **exchange of primary teeth** for permanent successors. *Second premolar* - The **second premolars** erupt even later, usually between **11 and 12 years of age**, replacing the primary second molars. - They are also involved in the **replacement of primary teeth**, not the initial permanent eruption. *Second molar* - **Second molars** erupt much later than the first molars, typically between **11 and 13 years of age**, distal to the first molars. - They are part of the **later stages of permanent dentition development**.
Question 6: Which of the following conditions is NOT associated with delayed dentition?
- A. Down syndrome
- B. Cystic fibrosis (Correct Answer)
- C. Congenital hypothyroidism
- D. Rickets
Explanation: ***Cystic fibrosis*** - **Cystic fibrosis** primarily affects exocrine glands, leading to issues in the respiratory and digestive systems, and does not directly impact tooth development or eruption timing. - While patients with cystic fibrosis may have other oral health concerns due to medications or nutritional deficiencies, **delayed dentition** is not a characteristic feature of the condition itself. *Down syndrome* - Children with **Down syndrome** often experience generalized developmental delays, including delayed eruption of both primary and permanent teeth. - Other common oral manifestations in Down syndrome include **microdontia**, **taurodontism**, and a higher incidence of **periodontal disease**. *Congenital hypothyroidism* - **Congenital hypothyroidism** is associated with significant developmental delays, including skeletal maturation and delayed tooth eruption. - The reduced metabolic rate due to thyroid hormone deficiency impacts bone and tooth development. *Rickets* - **Rickets**, caused by a deficiency in vitamin D, calcium, or phosphate, leads to inadequate mineralization of bone and cartilage, which can affect tooth development and eruption. - Oral manifestations of rickets include **delayed tooth eruption**, enamel hypoplasia, and a higher susceptibility to dental caries.
Question 7: Epulis arises from -
- A. Enamel
- B. Root of teeth
- C. Gingiva (Correct Answer)
- D. Pulp
Explanation: ***Gingiva*** - **Epulis** refers to a localized, tumor-like enlargement of the **gingiva** (gum tissue). - These lesions are typically inflammatory or reactive in nature, arising from the connective tissue of the gum. *Enamel* - **Enamel** is the hard, outermost protective layer of the tooth crown, which is of ectodermal origin. - Lesions originating from enamel itself are rare and typically involve developmental defects or structural damage, not soft tissue growths like epulis. *Root of teeth* - The **root of the teeth** is embedded in the alveolar bone and covered by cementum, with the surrounding structures including the periodontal ligament and alveolar bone. - While infections or cysts can arise from the root, epulis specifically describes a growth of the overlying **gingival tissue**. *Pulp* - The **pulp** is the soft tissue inside the tooth containing nerves, blood vessels, and connective tissue. - Pathologies originating from the pulp are typically infectious (pulpitis), degenerative, or involve growth of odontogenic tissues (e.g., pulp polyps within the tooth chamber), not surface gingival lesions.
Question 8: Kennedy phenomenon is seen in:
- A. Burns
- B. Gunshot injury (Correct Answer)
- C. Contusion
- D. Road traffic accident
Explanation: ***Gunshot injury*** - The **Kennedy phenomenon** describes the pattern of injury observed when a **bullet passes through a body part**, leaving an **exit wound larger than the entrance wound**. - This occurs because the bullet creates a **temporary cavity** that collapses, and the tissue at the exit point is stretched beyond its elastic limit, resulting in a larger defect. *Burns* - Burns are injuries caused by heat, chemicals, electricity, or radiation, resulting in **tissue destruction** and often characterized by **blistering, charring, and loss of skin integrity**. - While burns can cause tissue damage, the mechanism of injury and the resulting wound characteristics are distinctly different from the **ballistic trauma** described by the Kennedy phenomenon. *Contusion* - A **contusion**, or bruise, is a type of injury caused by **blunt force trauma** that damages small blood vessels under the skin, leading to discoloration without breaking the skin surface. - This injury mechanism involves **crushing of tissues** and local hemorrhage, which is fundamentally different from the passage of a projectile through tissues. *Road traffic accident* - A road traffic accident can result in a wide range of injuries, including **blunt force trauma**, **lacerations**, **fractures**, and **internal organ damage**. - While significant tissue damage can occur, the specific pattern of an **entry and a larger exit wound** resulting from a penetrating projectile is not a defining characteristic of RTA injuries.
Question 9: The primary indication for enucleation in pediatric patients is:
- A. Panophthalmitis
- B. Acute congestive glaucoma
- C. Retinoblastoma (Correct Answer)
- D. None of the options
Explanation: ***Retinoblastoma*** - **Retinoblastoma** is a malignant tumor of the retina commonly seen in children, and **enucleation** (surgical removal of the eye) is frequently the primary treatment to prevent tumor spread and save the child's life. - The decision for enucleation is based on the tumor's size, location, and potential for dissemination, especially when other globe-sparing therapies are not feasible or fail. *Panophthalmitis* - **Panophthalmitis** is a severe infection involving all coats of the eye and orbital tissues, which can be managed with aggressive antibiotic therapy. - While enucleation might be a last resort in cases of uncontrolled infection and severe pain, it is not the primary indication, especially in pediatric patients where globe salvage is often attempted first. *Acute congestive glaucoma* - **Acute congestive glaucoma** involves a sudden, severe increase in intraocular pressure, causing pain and vision loss, but it is primarily managed with medical and surgical interventions to lower pressure. - Enucleation is not a standard treatment for acute glaucoma unless the eye is blind, painful, and unresponsive to all other treatments, and it is rarely the primary indication in children. *None of the options* - This option is incorrect because **retinoblastoma** is a well-established and common primary indication for enucleation in pediatric patients due to its life-threatening nature.