introduction

Introduction to Operative Dentistry

Dr. karam Ahmed Msc. In operative dentistry 3rd grade 2017

Operative DentistryConservative Dentistry

It’s the art and science of diagnosis, treatment and prognosis of defects of teeth. Such treatment should result in: Goals Restoration of proper tooth form. Function. Esthetic. Maintain physiological integrity and harmonious relation with surrounding tissues.

History

Previously was a just a practice not based on scientific knowledge. Louis Pasteur (France) Role of MO in disease. G.V Black (USA, 19th) related the clinical practice to scientific bases.

Indications

Indications are numerous, but can be categorized into the following primary needs: Caries. Malformed teeth. Discolored teeth. Fractured teeth. Replacement or repair of previous restorations.

Considerations

Infection control. Examine oral and systemic health of pt not only the affected tooth. Oral manifestation of other diseases. Understanding of restorative material properties. Understanding of oral environment to which the restoration placed. Understanding of biological bases and function of the various tooth component and supporting structures. Knowledge of correct dental anatomy. Effects of operative procedures on the treatments of other disciplines. Treatment plane.

Instruments in Operative Dentistry

Hand Instruments
Rotary Instruments

nib (face) - blade

Hand Instruments
Instrument Design
Single ended - Double ended
Shank
Shank
Handle
blade
blade
Cutting and non cutting

Instrument shank angles

Straight
Mon-angle
Bin-angle (contra-angled)
Triple-angle (contra-angled)
1-2mm
Performance, anti rotation
Axis

Instrument Nomenclature

Function: e.g. condensers, carvers, cutting inst. ……. etc. Manner of use: hand condenser, mechanical condenser … Design of working end: spoon excavator, sickle scaler.
Angulations of the shank: mon-angle, bin-angle, triple…

Cutting Instruments Formula

Four number code
Three number code
Expressed as a percent of 360 degrees

Example for measuring the 2nd number (cutting edge angle)

A
A
Long axis
Cutting edge
Angle measured between direction of cutting edge and long axis in clockwise direction
In this example the angle between cutting edge and long axis is about 280 degree. So the percentage of cutting edge angle from 360 degree is
280
360
Edge angle
100
=
Cutting edge angle = 80.5

Cutting instruments bevel

One bevel = Right or left, Single ended safer but double ended reduce time for instruments exchange
One bevel
Blank
Bi-beveled

Cutting instruments applications

Ordinary Hatchet excavator: cutting edge with same plane as that of handle’s long axis, and bi-beveled. Primarily used on anterior teeth for preparing retentive areas and sharpen internal line angles for direct gold restorations.Hoe excavator: planing walls and forming line angles in class III and IV for direct gold restorations. Excavators

Angle former: sharpen internal line angles and preparing retentive features for gold restorations. Primary cutting edge at an angle other than 90 degree to the blade.
Spoon excavator: removal of caries, usually bin angled or triple angled to facilitate accessibility.

Straight chisel: not angulated with one side bevel and cutting edge perpendicular to long axis of handle. used for cutting enamel and no need for right and left since a 180 degree turn of the instrument allows for its use for both side of the cavity. Bin-angle and Wedelstaedt chisels: cutting edge perpendicular to long axis of handle. used for cutting enamel.
Chisels
2nd cutting edges


Enamel hatchet: similar design to ordinary hatchet in that the cutting edge in a plane parallel to long axis of the handle, but the blade is larger and beveled on only one side, so it has left and right side. Gingival marginal trimmer: designed to produce proper bevels at gingival margins. Similar to enamel hatchet but the blade is curved and the cutting edge is at angle other than 90 degree with the blade, so if the second number of the formula is 90-100 this is used for distal margins, and if its 85-75 this is used for mesial margins. 100 and 75 pairs used for beveling inlay/onlay cavities while 85 and 90 pairs used for amalgam cavities. This instrument also used for rounding or beveling the axiopulpal line angles.

Mostly not present

Gingival trimmer
Enamel hatchet


Other cutting instruments Cleoid-discoid: used for caving unset amalgam and burnishing inlay/onlay margins

Knives: finishing knives, amalgam knives, gold knives. All used for trimming the excess filling materials at cavity margins. Files: different size and shape also used for trimming the excess of filling material particularly at gingival margins.

Instruments Techniques (Grasping) Modified pen grasp: greatest touch delicacy is permitted with this grasp. A pad of thumb, index and middle fingers contacting the instrument. While tip of ring and/or little fingers is used for rest or support on the nearby teeth surface of the same arch for better controlling the action and the magnitude of force applied. Palm is usually facing away from the operator. Inverted pen grasp: same as modified pen grasp except that the hand is rotated so that palm is facing more toward operator. Usually used with lingual surfaces of anterior teeth.


Palm and thumb grasp: similar to that used for holding a knife while paring the skin from an apple. Rest is provided by supporting the thumb on nearby teeth. Used for preparing incisal retention in class III cavities. Modified palm and thumb grasp: only used when its feasible to rest the thumb on the tooth to be prepared or the adjacent tooth.

The End