Dental Practice Questions

In root canal treatment (RCT), the most crucial area to seal is the apical 1/3. This refers to the bottom third of the root canal, near the apex of the tooth. Properly sealing this area is essential to prevent any bacteria or debris from entering the canal and causing infection or further damage. Focusing on sealing the apical 1/3 ensures the success of the RCT by creating a barrier against potential complications.

Radiotherapy can indeed increase the risk of developing caries (tooth decay) by decreasing salivary secretion. Saliva plays a crucial role in maintaining oral health by neutralizing acids, remineralizing teeth, and washing away food particles. However, radiotherapy can damage the salivary glands, leading to reduced saliva production. This decrease in salivary flow can result in a dry mouth, which creates an environment conducive to the growth of harmful bacteria and the development of caries. Therefore, the statement is true.

The periodontal ligament has multiple functions. It is responsible for the formation and maintenance of the periodontal tissues, which support the teeth. This is known as the formative function. Additionally, the ligament provides mechanical support to the teeth, allowing for their movement during chewing and other activities. This is the mechanical function. Lastly, the periodontal ligament contains sensory nerve endings, which provide feedback to the brain about the position and pressure on the teeth. This is the sensory function. Therefore, all of the above functions are performed by the periodontal ligament.

Based on the symptoms described (pain, bad breath, bleeding gingival) and the context provided (began over the weekend while studying for final examination), the most likely condition the patient may have is Acute necrotizing ulcerative gingivitis. This condition, also known as "trench mouth," is characterized by painful, bleeding gums, bad breath, and the presence of ulcers or necrotic tissue in the mouth. It is often associated with stress and poor oral hygiene, which could be exacerbated by the patient's intense studying for exams.

Patients on treatment with steroids are placed on antibiotics after oral surgical procedures because steroids can suppress the immune system, making the patient more susceptible to infections. Antibiotics help prevent or treat any potential infections that may arise due to the weakened immune response. This is particularly important after oral surgical procedures, as the mouth is a common site for bacterial colonization and infections.

The statement "Pulp chamber is lower 1st molar is mesially located" is true. In the lower first molar, the pulp chamber is indeed mesially located. The pulp chamber is the central space within the tooth that contains the pulp, which consists of nerves, blood vessels, and connective tissue. In the lower first molar, this pulp chamber is situated towards the mesial (front) aspect of the tooth. This anatomical arrangement is characteristic of the lower first molar and helps in understanding its internal structure.

The correct answer is preextraction cord. Preextraction cord is used to displace the gingival tissue away from the tooth before extraction, allowing for accurate impressions and selection of artificial teeth. This helps in achieving a better fit and aesthetic outcome for the patient. Postextraction cord, on the other hand, is used after extraction to control bleeding and promote healing.

The dentin composition is primarily made up of inorganic materials, which accounts for about 60-65% of its weight. In terms of volume, the inorganic content makes up around 70% of the dentin. This indicates that the dentin is predominantly composed of mineralized substances such as hydroxyapatite crystals. The remaining composition includes water, which accounts for about 25% of the weight and 12% of the volume, as well as organic materials, which make up approximately 43% of the weight and 20% of the volume.

Cerebral palsy is a neurological disorder caused by damage to the brain during development. It affects movement and posture, leading to difficulties in controlling muscles. This aligns with the description of the handicapped patient with a lesion in the central nervous system having different types of movement and posture disorders. Seizures and learning disabilities are not specifically mentioned in the given information, making cerebral palsy the most appropriate answer.

A higher modulus of elasticity means that the material is stiffer and less flexible. In the context of a partial denture, a more rigid structure is desired to provide better support and stability. Therefore, selecting a base-metal partial denture alloy with a higher modulus of elasticity would be more suitable than a Type IV gold alloy, which would be more flexible.

Fibroma is the most common benign tumor in the oral cavity. It is a slow-growing, painless, and non-cancerous tumor that typically arises from the connective tissue. Fibromas are usually firm, smooth, and can have a similar color to the surrounding oral tissues. They commonly occur on the gums, tongue, or inside the cheeks. Fibromas are often caused by chronic irritation or trauma, such as biting the cheek or using tobacco products. While fibromas are generally harmless, they may require removal if they cause discomfort or interfere with oral functions.

When injecting local anesthesia, it blocks the transmission of nerve impulses in the area where it is administered. This is achieved by temporarily inhibiting the function of nerve fibers, specifically the ones responsible for transmitting pain signals. As a result, the nerve impulse, which is an electrical signal that travels along the nerve fibers, is halted or stopped. Therefore, the statement that the nerve impulse stops when injecting local anesthesia is true.

Cavity varnish should be applied in at least two layers. Applying varnish in multiple layers ensures better coverage and protection for the tooth surface. The first layer acts as a base, sealing the tooth and providing a smooth surface for the subsequent layers. The second layer adds an extra protective barrier, enhancing the longevity of the varnish. Applying varnish in two layers also allows for better adherence to the tooth structure, reducing the risk of premature wear or detachment.

The best pontic is hygienic because hygiene is an important factor in dental care. A hygienic pontic would be easy to clean and maintain, reducing the risk of plaque buildup and bacterial growth. This would help prevent infections and promote oral health. A hygienic pontic would also be beneficial for the overall well-being of the patient, as it would contribute to a clean and healthy oral environment.

The correct answer is hybrid + rough filler. Hybrid composite is a type of composite material that combines the properties of microfilled and macrofilled composites. It has both small particles for a smooth finish and larger particles for strength and durability. The rough filler in the hybrid composite provides better mechanical properties and wear resistance, making it suitable for use in posterior teeth which experience higher chewing forces.

Erosion is the correct answer because it refers to the chemicomechanical loss of tooth tissue. This process occurs when acids, such as those found in certain foods and drinks, wear away the enamel on the teeth. Erosion can also be caused by stomach acid from conditions like acid reflux or bulimia. It is different from abrasion, which is the mechanical wearing away of tooth tissue, attrition, which is the natural wearing down of teeth from normal use, and decalcification, which is the loss of minerals from the tooth enamel.

P 14

Dentin bonding materials are used in dentistry to bond restorative materials to the natural tooth structure. These materials typically require conditioning time, which is the amount of time the material needs to be in contact with the tooth surface to ensure proper bonding. The correct answer of 15 seconds suggests that most dentin bonding materials only require a short conditioning time of 15 seconds. This indicates that these materials are efficient and can quickly bond to the tooth surface, saving time during dental procedures.

The correct answer is oblique because periodontal ligament fibers in the middle third of the root are arranged in an oblique manner. This arrangement helps to provide support and stability to the tooth by connecting it to the surrounding bone. The oblique orientation of the fibers allows for some flexibility and shock absorption during chewing and biting forces, preventing excessive stress on the tooth.

The correct answer is that enamel rods forming the margins would still be full length and supported on dentin. This is because even though the facial and lingual walls slightly converge occlusally, the enamel rods would still be intact and supported by the underlying dentin. This ensures that the enamel margins remain strong and stable, preventing any weakness or vulnerability in the restoration.

The description of the patient's symptoms, including painful mouth, palpable submandibular lymph nodes, fever, inflammation of the gingiva and alveolar mucosa, white debris on the gingival margins, ulceration within rings of intense inflammation, intact interdental papillae, heavy and viscous salivary flow, and absence of lesions on the extremities, is consistent with acute herpetic gingivostomatitis.

Splinting of several teeth together as abutments for a fixed prosthesis is done to distribute occlusal load. This means that by splinting multiple teeth together, the force of biting and chewing is spread across a larger area, reducing the stress on individual teeth. This can help prevent excessive force on any one tooth, which can lead to damage or failure of the prosthesis. By distributing the occlusal load, the splinting also helps to improve the longevity and stability of the prosthesis.

The statement is false because compomer and GI (glass ionomer) do not have the same fluoride content. Compomer is a type of dental material that is a combination of composite resin and glass ionomer, while GI is a dental material that contains fluoride. Therefore, the fluoride content in GI is higher than in compomer.

The correct answer is 20 sec. This is the recommended light curing time for a simple shallow class III composite. Curing time refers to the amount of time that the dental composite material needs to be exposed to the curing light in order to harden properly. In this case, a curing time of 20 seconds is sufficient to ensure that the composite material is fully cured and has achieved the desired strength and stability.

The correct answer is reducing overextended borders. When a mandibular partial denture with distal extension bases is lifted, it means that the denture is not fitting properly and is causing discomfort or instability. One possible cause for this issue is overextended borders, which means that the borders of the denture extend beyond the natural contours of the oral tissues. By reducing these overextended borders, the denture can be adjusted to fit more accurately and comfortably in the mouth, correcting the lifting issue. Narrowing the teeth, tightening the brace arms, or tightening the retention arms would not directly address the problem of overextended borders.

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The diagnosis of early necrotizing ulcerative gingivitis is best made on the basis of ulceration of the interdental papilla. This is because early necrotizing ulcerative gingivitis is characterized by the presence of painful ulcers in the interdental papilla, which are the triangular gum tissues between the teeth. Biopsy, exfoliative cytology, and bacteriologic examination can also be helpful in confirming the diagnosis, but the presence of ulceration in the interdental papilla is the most indicative sign of this condition. Ulceration in the alveolar mucosa may be present in more advanced stages of the disease.

Amalgam restoration has been proven to have the characteristics of decreased micro leakage with aging and being the least technique sensitive of all current direct restorations. This means that over time, the risk of leakage around the restoration decreases, and it is less likely to be affected by variations in technique during placement. Therefore, the correct answer is 1 & 2.

During the condensation step of the amalgam restorative procedure, the premeasured capsules are condensed and shaped to fill the prepared cavity. This involves applying pressure to the capsules, which can cause the mercury to vaporize. The other options, such as mulling, carving, trituration, and high-speed evacuation, do not involve the same level of pressure or manipulation of the capsules, making condensation the most likely step for mercury vaporization to occur.

Orthognathic ridge relationship (class II) refers to a specific type of jaw relationship where the upper jaw is positioned further forward than the lower jaw. This can present several challenges when constructing a complete denture prosthesis. One of these challenges is the requirement of a minimum interocclusal distance, which means that there needs to be a certain amount of space between the upper and lower teeth when the jaws are in a resting position. This is not a problem associated with class II ridge relationships, as they typically have a greater range of jaw movement in function. Therefore, the correct answer is that class II ridge relationships do not require a minimum interocclusal distance.

The correct answer is cementoblastoma. Cementoblastoma is a rare benign tumor that arises from the cementum, a calcified substance that covers the roots of teeth. It typically presents as a slow-growing swelling in the jaw, often in the angle of the mandible. On radiographs, it appears as a radio-opaque mass with a well-defined radiolucent border. Osteoma and osteosarcoma are both bone tumors, but they do not typically present with the same radiographic features as cementoblastoma.

In constructing complete dentures for a patient with a debilitating disease, all of the above principles should be considered. Maximum extension is important to ensure proper support and stability of the dentures. A narrow occlusal table helps in maintaining proper occlusion and preventing excessive forces on the dentures. A non-pressure impression technique is necessary to minimize discomfort and trauma to the patient's oral tissues. Therefore, all of these principles are crucial in providing the best possible denture treatment for a patient with a debilitating disease.

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The statement is incorrect. Cementum does not contain cells like bone. Cementum is a mineralized tissue that covers the root surface of teeth. It is not yellow in color in vital, extracted, or avulsed teeth. The color of cementum can vary depending on various factors, such as age and oral health, but it is not necessarily dark in non-vital teeth.

The diameter of the bur, sharpness of the bur, bur/tooth contact time, type of coolant used, and amount of force applied to the bur all influence tooth temperature during a cutting procedure. The diameter of the bur affects the surface area of the tooth being cut, which can impact temperature. The sharpness of the bur determines how efficiently it cuts, which can affect the temperature generated. The bur/tooth contact time refers to how long the bur is in contact with the tooth, which can influence temperature. The type of coolant used helps to dissipate heat and can impact temperature. The amount of force applied to the bur can also affect the temperature generated during the cutting procedure.

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The answer "more than 12 blades" suggests that the facial nerve supply is extensive and complex. This could indicate that the facial nerve innervates a large number of muscles and structures in the face, requiring a greater number of blades for dissection or surgical procedures. It implies that the facial nerve has multiple branches and provides motor and sensory innervation to various regions of the face.

The correct answer is "rubber dam has been placed" because a rubber dam is a protective barrier that isolates the tooth being treated from saliva and other contaminants in the mouth. By placing the rubber dam before the final removal of carious tooth structure, the dentist ensures a clean and dry operating field, reducing the risk of contamination and infection. This step is particularly important when pulp exposure is anticipated to prevent bacteria from entering the pulp chamber and causing further damage or infection.

Flat bones do not grow by endochondral ossification. Endochondral ossification is the process by which long bones, such as the femur or humerus, grow and develop. It involves the replacement of cartilage with bone tissue. Flat bones, on the other hand, develop through a different process called intramembranous ossification. In this process, bone tissue forms directly within a membrane, without the involvement of cartilage. Therefore, the statement that flat bones grow by endochondral ossification is false.

The dental pulp is responsible for several functions in the tooth, including support, sensory perception, dentin repair, and circulation. However, it does not play a direct role in cementum repair. Cementum is a specialized tissue that covers the root of the tooth, and its repair is primarily carried out by cementoblasts, which are cells located in the periodontal ligament. Therefore, the dental pulp does not have a direct involvement in cementum repair.

A broken stress or non-rigid type fixed bridge is indicated when the retainers cannot be prepared to draw together without excessive tooth reduction. This means that the retainers cannot be designed in a way that allows them to come together without removing too much of the natural teeth. In such cases, a non-rigid type bridge is used to replace two or three missing teeth, ensuring that the retainers do not require excessive tooth reduction.

Drying the prepared tooth with alcohol and warm air before cementation of a crown can increase the possibilities of pulp damage. This is because alcohol and warm air can dehydrate the tooth structure, making it more brittle and susceptible to damage. Additionally, the drying process can remove any protective moisture or natural lubrication in the tooth, causing friction and potential damage during crown placement. Therefore, it is important to properly wipe the tooth dry to minimize the risk of pulp damage.

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Anachoresis refers to the attraction or fixation of microorganisms in areas of inflammation. This process occurs when microorganisms are drawn to inflamed tissues or organs, where they can proliferate and cause further infection or damage. It is a key mechanism in the spread and progression of infectious diseases.

The correct answer is "The probing was done too vigorously." This is because if the pt gingiva is described as pink, firm, and stippled, but the patient complains of bleeding gums and bleeds upon probing, it indicates that there is inflammation present in the superficial tissues. The disease may or may not be chronic in nature, but the statement about the probing being done too vigorously is not true as it does not explain the bleeding gums and inflammation.

The correct answer is "shape or form of the preparation of the surface of the tooth." This means that the outline form of a cavity preparation refers to the shape or form of the preparation on the surface of the tooth. It does not refer to the shape or form after carious dentin has been excavated or after the retention form has been completed.

GR 26

During pregnancy, hormonal changes can alter the body's response to local irritation, leading to gingivitis. This means that the tissue in the gums may react differently to the usual irritants, causing inflammation and overgrowth of tissue. It is not solely caused by an overgrowth of tissue unrelated to local irritation or an increase in local irritation by an alteration of the saliva, but rather a combination of these factors.