NDAEB Exam Prep . 292 Questions and Correct Answers, With Complete Solution 2024. Actual Exam Questions Included.

NDAEB Exam Prep . 292 Questions and Correct Answers, With Complete Solution 2024. Actual Exam Questions Included. What two basic methods are used to acquire a digital x-ray image? Direct imaging(sensor) & indirect imaging(PSP) Advantages of Digital Radiography Immediate viewing of images, less radiation, no chemicals, ability to enhance images, communication with other dentists, no more lost films, remote consultation capability Disadvantages of Digital Radiography Cost, converting previous records to digital, learning the computer software, thickness and rigidity of sensors, infection control What is intraoral film composed of? Film Base - Clear Cellulose Acetate Thin Adhesive Layer Silver Halide Crystals - absorb radiation A protective layer to protect the emulsion surface. What is a latent image? The image on the film that is not yet visible because it has not been processed. What does 'film speed' refer to? The amount of radiation that is required to produce a radiograph of standard density. True or false: The larger the silver halide crystals, the faster the film speed? True What is the fastest film speed currently available? F-Speed. (It reduces patient exposure to radiation by 20-60% compared to E or D speed film) What are the 3 types of x-ray film used in dental radiography? Intraoral film, extraoral film, and duplicating film. When does a "Herringbone" pattern occur on dental film? When it is placed in the mouth backwards. What are the 5 basic sizes that intraoral film comes in? Child Size: 0 Narrow Anterior: 1 Adult Size: 2 Preformed bitewing: 3 (infrequently used) Occlusal: 4 What are two common extraoral radiographs taken? Panoramic and Cephalometric. What is an intensifying screen? A device that intensifies or increases the effect of radiation and thus decreases the amount of exposure time needed. It is coated with phosphor which gives off light when struck by x-radiation. What are the 5 steps in processing film? 1. Developing (reduce the silver halide crystals into black metallic silver) 2. Rinsing (remove developer from film) 3. Fixing. (use an acidic solution to remove unexposed silver halide crystals) 4. Washing (wash the film) 5. Drying What are the two techniques that can be used for exposing intraloral images? Bisecting & Paralleling 5 Basic Rules of the Paralleling Technique 1. Placement: it must cover correct teeth to be examined 2. Position: it must be parallel to the long axis of the tooth. 3. Vertical Angulation: Central ray must be directed perpendicular to the receptor & tooth. 4. Horizontal Angulation: Central ray must be directed through the contact areas. 5. Central Ray: it must be centered on the receptor. Why is it important to have an 'exposure sequence' for receptor placement? To ensure an area is not omitted or exposed twice. What occurs if the horizontal angulation is incorrect? Overlapping of teeth. What two errors can occur if the vertical angulation is incorrect? Foreshortened or elongated images. What qualities must an endodontic x-ray have? Tooth centered on the image At least 5mm of bone visible beyond apex of the tooth The image is as anatomically accurate as possible Two methods of mounting radiographs are: 1. Labial mounting method: radiographs placed in the mount with the raised dots facing up (as if the viewer is looking directly at the pt) 2. radiographs placed in the mount with the raised dots facing down (as if the viewer is inside the patients mouth looking out) Two types of panoramic machines are in use today: Film-based imaging & direct digital imaging. The main difference is the image receptor, digital units use a sensory array rather than film. What is Cone Beam Computed Tomography? Use of a cone-shaped x-ray beam to acquire three-dimensional information. What is a film grid? (used for extraoral imaging) It is used to reduce the amount of scatter radiation that reaches an extraoral film during exposure. What is a Lateral Cephalometric Projection used for? Used to evaluate facial growth and development, trauma, disease, and developmental abnormalities. It shows the bones of the face and skull as well as the soft tissue profile. What is a Posteroanterior Projection used for? Used to evaluate facial growth and development, trauma, disease, and development abnormalities. It shows the frontal and ethmoid sinuses, the orbits, and the nasal cavities. What happens if a patient does not remove jewellery or metallic/radiodense objects from their head/neck? Ghost images If a lead apron is incorrectly placed on a pt during a panoramic radiograph, what occurs? "Lead Apron Artifact" a radiopaque cone-shaped artifact results. What happens if a patient's chin is positioned too high during a pan? It will create a "reverse smile line" What happens if a patient's chin is positioned too low during a pan? It will create an "exaggerated smile line" What are three types of stress and strain? Tensile stress: pulls and stretches a material Ex. tug-of-war Compressive stress: pushes a material together. ex. chewing Shear stress: the breakdown of material as the result of something sliding over two areas. ex. cutting with scissors. What is amalgam alloy powder composed of? Silver - gives it its strength. Tin - gives it workability and strength. Copper - gives it strength and resistance to corrosion. Zinc - to suppress oxidation. What is the composition of a composite resin? 1. An organic resin matrix. 2. Inorganic fillers. 3. A coupling agent. 4. pigments. What is the resin matrix in a composite resin? A fluid-like material called dimethacrylate or BIS-GMA. What is the filler in a composite resin? Inorganic fillers in a composite resin include quartz, glass, silica particles, and colorants. They add strength and other characteristics needed in a restorative material. Composites are classified by particle size as: Megafill, macrofill, midifill, minifill, microfill, and nanofill. What is the coupling agent used for in a composite resin? It strengthens the resin by chemically bonding the filler to the resin matrix. What are pigments used for in a composite resin? So a composite material can match a tooth colour. What is Polymerization? The process by which resin material is changed from a pliable state into a hardened restoration. This occurs through auto-curing or light-curing. True of false: Glass ionomers release fluoride? True. What is IRM? A reinforced zinc-oxide eugenol (ZOE) composition. The eugenol has a sedative effect on the pulp. What do noble metals used for cast restorations consist of? Gold, palladium, and platinum. What are the four types of gold alloys? 1. Soft, type I : 83% noble metals and are used for casting inlays. 2. Medium, type II : 78% noble metals and can be used for almost all types of cast inlays and posterior bridge abutments 3. Hard, type III : 77% noble metals and are acceptable for inlays, full crowns, three-quarter crowns, and anterior or posterior bridge abutments 4. Extra hard, type IV : 75% noble metals and are also referred to as partial denture alloys; they are designed for crowns, bridges, and cast-removable partial dentures. What type of restoration is made in a dental laboratory? Indirect Restoration What are 4 types of pulpal stimuli? Physical: thermal changes from hot & cold as well as electrical energy created by other metals that come in contact with the tooth. Mechanical: vibrations from the handpiece, or or 'traumatic occlusion' (when a persons' bite does not occlude properly) Chemical: occurs as a result of acidic material such as saliva reaching tissues. Biologic: bacteria from saliva coming into contact with pulpal tissues or when not all carious structure was removed. Where is a dental liner placed? At the deepest portion of a preparation. What does a dental liner do? Protect pulpal tissue from irritation caused by physical, mechanical, chemical, and biologic elements. Calcium Hydroxide is frequently selected as a liner because of its unique characteristics: 1. Protects pulp from chemical irritation through its sealing abilities. 2. Stimulates production of reparative or secondary dentin. 3. Compatible with ALL types of resto material. What two ways are liners supplied as? A two-paste system or a light-cured material. Where is dental varnish placed? Within the entire preparation. What does a dental varnish do? 1. Seals dentinal tubules. 2. Reduces microleakage around a restoration. 3. Acts as a barrier to protect the tooth from highly acidic cements such as zinc phosphor. Is varnish placed before or after the dental liner? Always after the liner. True or false: Dental varnish interferes with the bonding and setting reaction of composite and glass ionomer restorations? True. Varnish is contraindicated with composite and glass ionomer restorative material. What is the other named used for a desensitizer? Primer. What does a desensitizer do? It seals the dentinal tubules thus preventing oral fluids from seeping between the tooth and the restoration. What 3 ways does base provide pulpal protection? Protective base: placed when necessary to protect pulp before the restoration is placed, postop sensitivity and damage to pulp may occur without it. Insulating base: placed in deep cavities to protect tooth from thermal shock. Sedative base: help soothe pulp that has been damaged by decay or has been irritated during the process of removing decay. 4 different types of base materials: Zinc oxide-eugenol (ZOE) - insulating/sedative base. Eugenol has a soothing effect on painful, irritated pulp. Cannot be used with composite restoration, glass ionomer, or other resin resto's. Zinc Phosphate - insulating base. very acidic, can be irritating to pulp. necessary to place cavity liner prior. Polycarboxylate - protective/insulating base. Nonirritating and can be placed under all types of restorations. Glass ionomer - excellent adhesion to enamel and to dentin. fluoride release. Where is a base placed in a cavity prep? Entire pulpal floor is covered with a thickness of 1-2mm. What is tooth etchant a critical component for a restoration? It helps restorative material create a better chemical bond with the tooth structure. What does dental etchant do? Removes the smear layer in preparation for a composite resin or sealant. What is the most common recommended time for dental etchants to be placed on a tooth? 15-20 seconds. What is the 'smear layer'?