Therapeutic Dentistry Exam Questions - Carious Cavities by Black

Therapeutic Dentistry Exam Questions: Carious cavities by black Questions 31-40

31. Classification of carious cavities by Black?

32. Stages of cavity preparation for I and V classes? 1. 2. 3. 4. 5.

Anaesthetizing Disclosure: open and enlargement of carious cavity, use round burs  Nectroctomy  Nectroctomy –  total  total or partial Formation of carious cavity for placement of filling Smooth out the edges of the enamel

33. Basic principles of preparation and formation of cavities? 1. Establishing outline form a. Extend the preparation of cavity to sound enamel  b. Extend the preparation for prevention –  prevention  –  remove  remove some healthy tissue to prevent propagation of caries c. Provide adequate access –  access  –  hence  hence cavity must be large enough so that all the carious tooth structure is removed d. Provide resistant form –  form –  the  the restorative material and remaining supportive tooth structure must be able to withstand occlusal forces 2. Provide retention form: to prevent restorative material from falling out e.g. retentive grooves for amalgam and acid itching for enamel 3. Remove caries and treat the pulp: a. Use slow hand piece  b. Use dentinal liners or cements to protect the dental pulp from bacterial penetration, sensitivity to heat and stimulate the production of secondary dentine 4. Finish the preparation walls 5. Clean the preparation 6. Final evaluation of the preparation 34. Features of V class cavity preparation?  For class V preparation, it should be an oval shape, walls and the bottom should at right angle, and bottom is convex because of pulp proximity at cervical area thus preventing pulp exposure

35. Features of I class cavity preparation? Cavity preparation should be with straight walls at right angle to the bottom, shape of the cavity should be cylindrical, square, rhombic, x like 36. Stages of cavity preparation of these classes? Common stages of dental hard tissues preparation 1. Anaesthetizing 2. Disclosure (opening and enlargement) - use round burs of same size as the cavity 3.  Necrotomy –   Necrotomy –  Removal  Removal of pathological tissue using an excavator 4. Formation of carious cavity for filling –  filling  –  use  use fissure and inverted cone burs 5. Finishing and polishing the edge of enamel Elements of carious cavity include: bottom, floor, walls, edges and corners

A cavity preparation may have a: 1. Main Cavity: is Cavity: is prepared in place of pathological process 2. Additional cavities: are cavities: are prepared on healthy tissue for retention of restorative materials General rules for preparation of cavities 1. Surface of floor to wall at right angles 2. Form a cavity box  – except for class v- use an oval shape 3. Floor of cavity should be flat or resemble occlusal surface

37. Basic principles of preparation and formation of cavities II, III, IV classes by Black? Class 2:  if there is no neighboring tooth and the cavity is below the equator it is formed on the proximal surface. If the access is complicated, a cavity is extended to the occlusal surface and an additional cavity is formed there, the additional cavity occupies 1/3 to ¼ length of the occlusal surface. Class 3:  the prepared cavity should have the shape of a triangle, it may be extended to the lingual surface where an additional cavity is formed there. Class 4:  an additional cavity is formed either in the area of incisal edge or on the palatal/lingual surface within the limits of dentin

39. Complications during the preparation of cavities II, III, IV classes by Black?

40. The definition of "contact point"? Restorations involving interproximal surfaces i.e. class 2 or class 4. The restoration of contact point will prevent the development of further periodontal diseases. Instruments used: matrix band is placed to help retain the restorative material during placement, to give shape to the  proximal surface surface of the the restoration restoration and to allow close close adaptation adaptation of the restorative restorative material to the cavity. cavity. Common Common types types of restorative material include: 1. Siqveland: straight straight band and a holder. Both the band and the holder are removed from the tooth directly sometimes results in removal of the part of newly packed amalgam 2. Tofflemine: in this system the holder is removed before the bend, this may prevent removal of the restoration with the bend 3. Circumferential matrix: no holder, the band is tightened by spring mechanism

4. Ivory: metal band replaces only one proximal wall and th erefore can’t be used for the cavities involving both  proximal walls walls The next step is to place a wedge at the cervical region of the band normally from buccal aspect  –  functions  functions of the wedge: Help retain band space Shapes the band at cervical margin of tooth Prevents excess material at the cervical area of the cavity forming a ledge It separates the teeth slightly so that when the matrix band is removed there is no space between the adjacent teeth and a tight contact is f ormed    

38. Features of additional cavity formation during the preparation of II class by Black?