Intracoronal retainer placed in the abutment tooth has the following disadvantage:

 # Intracoronal retainer placed in the abutment tooth has the following disadvantage:

A. It is unaesthetic

B. They cannot provide support and stability

C. Difficult laboratory procedures

D. Difficult to repair and replace

The correct answer is D. Difficult to repair and replace.

The advantages of internal or precision attachments are improved esthetics by elimination of a visible retentive component and vertical support. Its disadvantages are difficulty in repair and replacing, greater cost to the patient and inability to use in teeth having short clinical crowns and tissue supported distal extension denture bases. 

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A minor connector contacting the axial surface of an abutment should not be located on a:

 # A minor connector contacting the axial surface of an abutment should not be located on a:

A. Flat surface

B. Concavo-convex surface

C. Convex surface

D. Concave surface

The correct answer is C. Convex surface.

Minor connector contacting the axial surface of an abutment should not be located on a convex surface. Instead, it should be located in an embrasure. 

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The first step in surveying the cast for RPD is:

 # The first step in surveying the cast for RPD is: 

A. Establishment of guiding plane

B. Establishments of undercuts for retention

C. Establishment of tooth contour for esthetics

D. Establishment of interferences for major connector

The correct answer is A. Establishment of guiding plane.

The step by step procedures in surveying are:

- Guiding planes

- Retentive areas

- Interferences

- Esthetics

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A wrought wire clasp is considered most effective in Kennedy Class:

 # A wrought wire clasp is considered most effective in Kennedy Class: 

A. III cases for periodontally weakened abutment teeth

B. I cases for periodontally weakened abutment teeth

C. II cases for the non edentulous side

D. IV cases with periodontally weakened teeth

The correct answer is B. I cases for periodontally weakened abutment teeth.

The wrought wire clasp is generally considered to flex and be kinder to the abutment tooth periodontally although it engages the undercuts about two to three times greater than a cast clasp. 

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# Cotton wool appearance is seen in:

 # Cotton wool appearance is seen in:

A. Paget’s disease

B. Osteomyelitis

C. Fibrous dysplasia

D. Achondroplasia

The correct answer is A. Paget's disease.

The radiographic appearance of chronic diffuse sclerosing osteomyelitis is, as the name suggests,

that of a diffuse patchy, sclerosis of bone often described as ‘cotton-wool’ appearance. This radiopaque lesion may be extensive and is sometimes bilateral. In occasional cases, there is bilateral involvement of both the maxilla and the mandible in the same patient. Because of the diffuse nature of the disease, the border between the sclerosis and the normal bone is often indistinct. The pattern may actually mimic Paget’s disease of bone or cemento-osseous dysplasia.

Reference: Shafer's 

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Pathological calcification is seen in:

 # Pathological calcification is seen in:

A. Scleroderma

B. Lichen planus

C. Dystrophic epidermolysis bullosa

D. Lupus erythematosus

The correct answer is A. Scleroderma.

Pathologic calcification is a common process in a wide variety of disease states; it implies the abnormal deposition of calcium salts, together with smaller amounts of iron, magnesium, and other minerals. When the deposition occurs in dead or dying tissues, it is called dystrophic calcification; it occurs in the absence of derangements in calcium metabolism (i.e., with normal serum levels of calcium). In contrast, the deposition of calcium salts in normal tissues is known as metastatic calcification and is almost always secondary to some derangement in calcium metabolism (hypercalcemia). Of note, while hypercalcemia is not a prerequisite for dystrophic calcification, it can exacerbate it.

Systemic sclerosis can be classified into two groups on the basis of its clinical course:

• Diffuse scleroderma, characterized by initial widespread skin involvement, with rapid progression and early visceral involvement

• Limited scleroderma, with relatively mild skin involvement, often confined to the fingers and face. Involvement of the viscera occurs late, so the disease in these patients generally has a fairly benign course. This clinical presentation is also called the CREST syndrome because of its frequent features of calcinosis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia.

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# Non disjunction of chromosome occurs in which stage?

 # Non disjunction of chromosome occurs in which stage?

A. Prophase

B. Metaphase

C. Anaphase

D. Telophase

The correct answer is C. Anaphase.

Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during cell division (mitosis/meiosis). There are three forms of nondisjunction: failure of a pair of homologous chromosomes to separate in meiosis I, failure of sister chromatids to separate during meiosis II, and failure of sister chromatids to separate during mitosis.

Meiosis II

Ovulated eggs become arrested in metaphase II until fertilization triggers the second meiotic division. Similar to the segregation events of mitosis, the pairs of sister chromatids resulting from the separation of bivalents in meiosis I are further separated in anaphase of meiosis II. In oocytes, one sister chromatid is segregated into the second polar body, while the other stays inside the egg. During spermatogenesis, each meiotic division is symmetric such that each primary spermatocyte gives rise to 2 secondary spermatocytes after meiosis I, and eventually 4 spermatids after meiosis II. Meiosis II-nondisjunction may also result in aneuploidy syndromes, but only to a much smaller extent than do segregation failures in meiosis I. 

Mitosis

Division of somatic cells through mitosis is preceded by replication of the genetic material in S phase. As a result, each chromosome consists of two sister chromatids held together at the centromere. In the anaphase of mitosis, sister chromatids separate and migrate to opposite cell poles before the cell divides. Nondisjunction during mitosis leads to one daughter receiving both sister chromatids of the affected chromosome while the other gets none. This is known as a chromatin bridge or an anaphase bridge. Mitotic nondisjunction results in somatic mosaicism, since only daughter cells originating from the cell where the nondisjunction event has occurred will have an abnormal number of chromosomes. Nondisjunction during mitosis can contribute to the development of some forms of cancer, e.g., retinoblastoma. Chromosome nondisjunction in mitosis can be attributed to the inactivation of topoisomerase II, condensin, or separase. Meiotic nondisjunction has been well studied in Saccharomyces cerevisiae. This yeast undergoes mitosis similarly to other eukaryotes. Chromosome bridges occur when sister chromatids are held together post replication by DNA-DNA topological entanglement and the cohesion complex. During anaphase, cohesin is cleaved by separase. Topoisomerase II and condensin are responsible for removing catenations. 

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