Abfraction is caused by

 # A patient had a non carious lesion on the lower premolar and was diagnosed as abfraction. Abfraction is caused by:

A. Excess intake of aerated drinks

B. Excessive forces during brushing

C. Flexure of the tooth from occlusal trauma

D. Leaching of 30% hydrogen peroxide during walking bleach

The correct answer is C. Flexure of the tooth from occlusal trauma.

The loss of tooth structure in the cervical areas (abrasion) is commonly seen as a rounded notch in the gingival portion of the facial aspects of teeth. In contrast to cervical lesions that develop from abrasion processes, idiopathic erosion lesions (“abfractions”) are cervical, wedge-shaped defects (angular as opposed to rounded) similar to the defects customarily associated with abrasion but in which one of the possible causative factors may include excessive flexure of the tooth as a result of heavy, eccentric occlusal forces.  

Ref: Sturdevant’s Art and Science of Operative Dentistry, 7th Edition, Page no 106

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Over contouring of class II restoration:

 # Over contouring of class II restoration:

A. Leads to healing of periodontal tissues

B. Reduces the plaque in the subgingival area

C. Reduces food impaction by tight contacts

D. Leads to inflammation of the marginal gingiva

The correct answer is D. Leads to inflammation of the marginal gingiva.

Normal tooth contours must be recreated in the performance of operative dental procedures. Improper location and degree of facial or lingual convexities may result in iatrogenic injury in which the proper facial contour is disregarded in the design of the cervical area of a mandibular molar restoration. Overcontouring is the worst offender, usually resulting in increased plaque retention that leads to a chronic inflammatory state of the gingiva.

Ref: Sturdevant’s Art and Science of Operative Dentistry, 7th Edition, Page no 12

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Retention form in class II cavity for amalgam

 # Retention form in class II cavity for amalgam is achieved from:

A. Reduction of cusps

B. Convergence of proximal and occlusal walls occlusally

C. Flat gingival seat

Parallel proximal and occlusal walls

The correct answer is B. Convergence of proximal and occlusal walls occlusally.

The design of preparation primary retention form is directly related to the retention needs of the anticipated restorative material. Amalgam restoration of a Class I or II preparation is retained by developing external tooth walls that converge occlusally. In this way, when the amalgam is placed in the preparation and hardens, it cannot be dislodged. However, excessive occlusal convergence of the external walls will result in unsupported enamel rods at the cavosurface margin and must be avoided.

Ref: Sturdevant’s Art and Science of Operative Dentistry, 7th Edition, Page no 128

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Initiator/accelerator systems needed for a light activated composite

 # Which of the following initiator/accelerator systems is needed for a light activated composite?

A. Peroxide amine

B. Diketone amine

C. Organic acid –peroxide

D. Organic acid- metal ion

The correct answer is B. Diketone Amine.

The light-cure process is activated when a diketone photosensitizer such as camphorquinone (CQ) absorbs a quantum of blue light and forms an excited-state complex (exciplex) with an electron donor such as an amine (e.g., dimethylaminoethyl methacrylate [DMAEMA]).

Ref: Phillip’s science of Dental Materials, 12th Edition, Page no. 289

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Most difficult teeth to anesthetize with irreversible pulpitis

 # What are the most difficult teeth to anesthetize with irreversible pulpitis?

a. maxillary molars

b. mandibular molars

c. maxillary anterior teeth

d. maxillary premolars

The correct answer is B. Mandibular molars.

With irreversible pulpitis, the teeth most difficult to anesthetize are the mandibular molars, followed by (in order) the mandibular and maxillary premolars, maxillary molars, mandibular anterior teeth, and maxillary anterior teeth.

Ref: Endodontics Principles and Practice, Torabinejad, Fifth Edition, Page e26

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Which of the following is classified as a procedural accident?

 # Which of the following is classified as a procedural accident?

a. Extensive caries preventing adequate rubber dam isolation

b. Inability to obtain reliable pulp testing results

c. A separated instrument

d. Swelling after nonsurgical root canal treatment

The correct answer is C. A separated instrument.

Procedural accidents are one reason for referral and are a direct result of treatment rather than preoperative conditions, diagnostic testing, or postoperative symptoms. A separated instrument is one of the most difficult accidents to correct.

Ref: Endodontics Principles and Practice, Torabinejad, Fifth Edition, Page e17

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Akhanda Smile Dental Clinic, Buddhachowk, Bharatpur Chitwan

 Name of Dental Clinic: Akhanda Smile Dental Clinic

Address: Buddhachowk, Bharatpur Chitwan (nearby BPKMCH)

Year of Establishment: 2018

Name of the chief Dental Surgeon: Dr. Laxman Poudel (21377), Dr. Shishir Poudel(20942)

CONTACT NUMBER: 9862448924

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