Dentosphere : World of Dentistry

 # Final determination of the dental arch form depends on: A. Angle’s classification B. Growth pattern C. Facial type D. Balance between extraoral and intraoral muscle forces The correct answer is D. Balance between extraoral and intraoral muscle forces. Although negative pressure is created within the mouth during sucking, there is no reason to believe that this is responsible for the constriction of the maxillary arch that usually accompanies sucking habits. Instead, arch form is affected by an alteration in the balance between cheek and tongue pressures. If the thumb is placed between the teeth, the tongue must be lowered, which decreases pressure by the tongue against the lingual of upper posterior teeth. At the same time, cheek pressure against these teeth is increased as the buccinator muscle contracts during sucking. Cheek pressures are greatest at the corners of the mouth, and this probably explains why the maxillary arch tends to become V -shaped with more constriction acr...

 # Which is not a method of gaining space? A. Proximal stripping B. Intrusion C. Uprighting of molars D. Derotation of posterior teeth The correct answer is B. Intrusion.  Space can be gained by: A.  Non Extraction   Proximal stripping   Arch expansion   Molar teeth distalization   Uprighting of tilted teeth   Derotation of posterior teeth   Proclination of anterior teeth B. Extraction   Balancing extractions   Compensating extractions   Phased extractions   Enforced extractions   Wilkinson extractions   Therapeutic extractions C. Surgical   Orthognathic surgery   Distraction osteogenesis CLICK HERE FOR MORE MCQs

 # How much root formation is complete when tooth erupts into the oral cavity? A. 100% B. 75% C. 60% D. 50%   The correct answer is B. 75%. The eruption of a permanent tooth can be delayed if its primary predecessor is retained too long. When this happens, the obvious treatment is to remove the primary tooth. As a general guideline, a permanent tooth should erupt when approximately three-fourths of its root is completed. If root formation of the permanent successor has reached this point while a primary tooth still has considerable root remaining, the primary tooth should be extracted. Reference: Contemporary Orthodontics, Fourth Edition, Proffit, Page 249 CLICK HERE FOR MORE MCQs

 # Which of the following cephalometric values should decrease for an individual between the ages of 8 and 18 years? A. FMA B. ANB C. GoGn-SN D. All of the above The correct answer is D. All of the above.  With the possible exception of those who have an openbite malocclusion, patients who have a Frankfort mandibular angle (FMA) within the normal range can generally be expected to show a reduction in this angle with continued growth. If, during orthodontic treatment, the FMA increases, then it may be expected to return to its former relationship, or less, if the patient continues to grow. If no further growth takes place, then the return to the original FMA will likely not occur. If, however, further growth occurs and the maxillary and mandibular teeth are retained in a position of minimal overbite, then the subsequent increase in posterior facial height and a leveling of the FMA may occur without an accompanying increase or relapse in the deep overbite. The magnitude of the A...

 # Gingival involvement is an unusual finding in one of the following conditions? A. Recurrent aphthae B. Pemphigoid C. Primary herpes D. Pyogenic granulomas The correct answer is A. Recurrent aphthae.  The first episodes of RAS most frequently begin during the second decade of life. The lesions are confined to the oral mucosa and begin with prodromal burning or the sensation of a small bump in the mucosa from 2 to 48 hours before an ulcer appears. During this initial period, a localized area of erythema develops. Within hours, a small white papule forms, ulcerates, and gradually enlarges over the next 48–72 hours. The individual lesions are round, symmetric, and shallow (similar to viral ulcers), but no tissue tags are present from ruptured vesicles, which helps distinguish RAS from diseases that start as vesicles, such as pemphigus, and pemphigoid. Multiple lesions are often present, but the number, size, and frequency vary considerably. The buccal and labial mucosae are mos...

 High blood pressure or Hypertension is blood pressure higher than normal. Blood pressure is expressed in A/B form where A is systolic pressure and B is diastolic pressure. High blood pressure is blood pressure above 140/90 mm Hg. Uncontrolled hypertension can lead to heart and kidney disease, stroke and blindness. But researches have shown that high blood pressure can be prevented by following the Dietary Approaches to stop Hypertension (DASH) eating plan. Dietary Approaches to Stop Hypertension (DASH) diet originated in the 1990s. Many researches were conducted in 1992 by National Institute of Health to find the effectiveness of DASH eating plan. The research concluded that dietary interventions alone can lower systolic blood pressure by 6-11 mm Hg. The DASH diet offer an alternative to drug therapy in hypertensives and may prevent hypertension in normotensives. In a study done in 2014,the DASH diet was found to result in significant decreases in systolic BP ( − 5·2 mmHg, 95 % CI...

 # X ray beam is filtered to: A. Soften the beam B. Restrict beam size C. Remove long wavelength  X rays D. Remove short wavelength x rays The correct answer is C. Remove long wavelength X rays. Although an x-ray beam consists of a continuous spectrum of x-ray photon energies, only photons with sufficient energy to penetrate through anatomic structures and reach the image receptor (digital or film) are useful for diagnostic radiology. Low-energy photons that cannot reach the receptor contribute to patient risk but do not offer any benefit. Consequently, it is desirable to remove these low-energy photons from the beam. This removal can be accomplished in part by placing a metallic disk (filter) in the beam path. A filter preferentially removes low-energy photons from the beam, while allowing high-energy photons that are able to contribute to making an image to pass through. Energy of x-rays depends directly on its frequency (E~f) and inversely related to wavelength (E~1/λ). Ele...