Chair and operator positions in dentistry Definition CAVITY

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Chair and operator positions in dentistry

Chair and operator positions in dentistry

Definition: CAVITY: “a cavity refers to a defect in enamel or in both enamel

Definition: CAVITY: “a cavity refers to a defect in enamel or in both enamel and dentine, subsequent to the destruction caused by dental caries” Cavity preparation: “alteration of defective, diseased or injured tooth structure by dental surgical procedure and subsequently shaping the remaining enamel and dentine to receive a restorative material such that tooth is returned to its normal form, function, health and esthetics (where needed)”

Intracoronal cavity preparation: “cavity that is prepared in the interior of the tooth” Extracoronal

Intracoronal cavity preparation: “cavity that is prepared in the interior of the tooth” Extracoronal cavity preparation: “Cavity preparation that involves external surface of the tooth and has walls that results from removal of most or all of the enamel”

Simple cavity: one surface Compound cavity: two adjoining surface Complex cavity: more than two

Simple cavity: one surface Compound cavity: two adjoining surface Complex cavity: more than two adjoining surface

Various walls of the cavity Wall: any surface of the cavity is referred to

Various walls of the cavity Wall: any surface of the cavity is referred to as a wall Internal wall: surface of the prepared cavity that does not extend to the exterior of the tooth External wall: surface of the prepared cavity that extends on to the exterior of the tooth Enamel wall: portion of the cavity wall that is composed of enamel Dentin wall: portion of the cavity wall that is composed of dentin

Floor / seat of the cavity: “any cavity wall that is flat and perpendicular

Floor / seat of the cavity: “any cavity wall that is flat and perpendicular to the forces acting occluso-gingivally” Step: “auxillary extension of the main cavity on to an adjoining surface”

Different walls in the cavity preparation: • Facial wall: labial & buccal • Lingual/palatal

Different walls in the cavity preparation: • Facial wall: labial & buccal • Lingual/palatal wall • Incisal/occlusalwall • Mesial/distal wall • Axial wall: wall nearest to the pulp and parallel to the long axis of the tooth • Pulpal wall • Gingival wall

Various angles in a cavity preparation: Angle: junction of two or more surfaces of

Various angles in a cavity preparation: Angle: junction of two or more surfaces of a prepared cavity Line angle: the angle formed at the junction of two adjoining walls Point angle: the angle formed at the junction of three adjoining walls Axial line angle: line angle parallel to the long axis of the tooth Pulpal line angle: line angle horizontal to the long axis of the tooth Cavosurface angle: angle formed at the junction of cavity wall and unprepared tooth surface

Bevel: “any abrupt incline between the two surfaces of the prepared tooth or between

Bevel: “any abrupt incline between the two surfaces of the prepared tooth or between the cavity wall and the cavosurface margins in the prepared cavity”

Classification of cavity

Classification of cavity

According to G. V. Black Class – I: Pit and fissure cavities present on

According to G. V. Black Class – I: Pit and fissure cavities present on the occlusal surface of molars and premolars, occlusal 2/3 of the buccal and lingual surface of molars and lingual surface of the anteriors

Class – II: Cavities present on the proximal surfaces of the posterior teeth

Class – II: Cavities present on the proximal surfaces of the posterior teeth

Class – III: Cavities present on the proximal surface of the anterior teeth without

Class – III: Cavities present on the proximal surface of the anterior teeth without involving the incisal angle

Class – IV: Cavities present on the proximal surface of the anterior teeth involving

Class – IV: Cavities present on the proximal surface of the anterior teeth involving the incisal angle

Class – V: Cavities present on the cervical 1/3 of all the teeth

Class – V: Cavities present on the cervical 1/3 of all the teeth

Class – VI: Cavities present on the cuspal tips of posterior teeth or incisal

Class – VI: Cavities present on the cuspal tips of posterior teeth or incisal edge of the anterior teeth

Chair and operator positions in operative dentistry

Chair and operator positions in operative dentistry

 • Efficient patient and operator position is beneficial for the welfare of both

• Efficient patient and operator position is beneficial for the welfare of both persons • Patient who is in a comfortable position is more relaxed, has less muscular tension and more cooperative • With comfortable operator position, operator will experience less physical strain and fatigue and reduces the possibility of developing musculoskeletal disorders

 • Operator should avoid unnecessary slumping of the shoulder and curvature of the

• Operator should avoid unnecessary slumping of the shoulder and curvature of the spine • When the back and the chest are held in the upright position with the shoulders squared, proper breathing and circulation are promoted • Proper balancing and weight distribution on both the feet is essential when operating from a standing position

Chair and patient positions • Modern dental chairs are designed to provide total body

Chair and patient positions • Modern dental chairs are designed to provide total body support in any chair positions • Patient should have direct access to the chair. Chair height should be low, the back rest upright and the arm rest adjusted to allow the patient to get into the chair • After the patient is seated, arm rest is returned to the normal position • The head rest cushion is adjusted to support the head and elevate the chin slightly away from the chest

 • Most common patient position for the operative dentistry are supine or reclined

• Most common patient position for the operative dentistry are supine or reclined 45 degree

Operating positions • Described by the location of the operator or by the location

Operating positions • Described by the location of the operator or by the location of the operator’s arm in relation to the patient position • Right handed operator: right front – 7 o’ clock right – 9 o’ lock right rear – 11 o’ clock direct rear – 12 o’ clock

 • Left handed operator left front – 5 o’ clock left – 3

• Left handed operator left front – 5 o’ clock left – 3 o’ clock left rear – 1 o’ clock

 • Right front: - mandibular anterior teeth - mandibular posterior teeth on the

• Right front: - mandibular anterior teeth - mandibular posterior teeth on the right side - maxillary anterior teeth • Right : - facial surfaces of mandibular and maxillary posterior teeth and occlusal surface of the mandibular right posterior teeth

 • Right rear: - Lingual, incisal and occlusal surfaces of the maxillary teeth

• Right rear: - Lingual, incisal and occlusal surfaces of the maxillary teeth - Mandibular teeth on the left side - also called as UNIVERSAL POSITION • Direct rear: - lingual surface of the mandibular anterior teeth

General considerations • Maxillary arch - occlusal surface – perpendicular to the floor •

General considerations • Maxillary arch - occlusal surface – perpendicular to the floor • Mandibualr arch - occlusal surface – 45 degree to the floor • Left hand is used to retract the lip and cheek • Instrument exchange – over the chest of the patient

Operating stool • Thighs should be parallel to the floor • Lower part of

Operating stool • Thighs should be parallel to the floor • Lower part of the leg should be perpendicular to the floor • Feet should rest completely on the floor • Back rest of the operating stool is adjusted to the level in such a way that the operator should lean slightly towards the patient