DA III Unit 2

Dental occlusion

The touching together or the maxillary and mandibular teeth during various jaw relationships

• The functional relationship of all the components of the masticatory system (bones, teeth, TMJ, lips/cheeks, muscles, etc.)

Centric relation

Most stable and most posterior position

• Position of the mandible relative to the maxillaa

• Determined by the maximum contraction of the jaw mucsles

• Bone to bone relationship guided by muscles and TMJ

• Not related to the interdigitation of teeth

• NOT CENTRAL OCCLUSAL

• NOT RELATED TO TEETH ONLY MUSCLES

Centric Occlusion

Most stable and most posterior position, also known as the habitual position of closure or maximum intercuspation

• Determined by teeth

• All teeth are in proper contact, may or may not coincide with centric relation

Proper contact (centric occlusion)

Buccal cusps of mand. teeth touch the marginal ridges and central fossae of max. molars. Lingual cusps of max. teeth touch marginal ridges and central fossae of mand. molars.

Open bite

Caused by tongue-thrusting

Protrusion

Caused by a lack of labial support

Retrusion

Caused by overactive lips

Overbite

VERTICAL overlap of the maxillary incisors

• Can be slight, moderate, or severe

Overjet

HORIZONTAL overlap of the maxillary incisors

• Measures in milimeters

• Teeth flare outward

Anterior guidance (protrusive guidance)

Forward and backward

• Lower incisors are riding up on the lingual surface of upper incisors and forward; this guidance allows for posterior teeth to disengage during protrusive excursion

• Important concept for people who have excessive wear on roots, erosion, gum recession, TMJ

Canine guidance (Lateral guidance)

Side to side

• The lower canine is riding up on the lingual surface of the upper canines, AKA canine protected occlusion

• Allows for posterior teeth to disengage during lateral excursion

• Important to know for people who have excessive wear on their teeth, erosion of the roots, gum recession, and TMJ

Lateral excursation

Right or left/side to side/ guided by canines

Protrusion excursation

Move forward and backward/guided by incisors

Rules of centric occlusion: The marks left by articulating paper are ___ in size, intensity and shape

Even

Rules of occlusion: Lateral excursive contacts; ___ marks (lines) should be seen

NO

Protrusive contacts; When the mandible protrudes and anterior teeth are edge to edge, ___ lines should be seen after biting down

NO

Occlusal plane

The plane formed by the occlusal surfaces of teeth

Curve of spee

The curved alignment of the occlusal plane allows for more occlusal space

• More prominent curve is better

Overbite

The VERTICAL overlap of the maxillary incisors

• Can be slight, moderate, or severe

Overjet

The HORIZONTAL overlap of maxillary incisors

• Measures in MILLIMETERS

• Teeth flare OUTWARDS

In centric occlusion, maxillary teeth are positioned ___ to the ____ surfaces of all mandibular teeth

Facially, facial

Buccal cusp tips of maxillary posterior and lingual cusps of mandibular are _______

Non working cusps (they don’t occlude against opposing tooth structure)

Lingual cusp tips of maxillary posterior teeth and buccal cusp tips of mandibular posterior teeth are _____

Functional (working) cusp

Consequence of premature contact (too high)

• Latrogenic disorders

• Excessive tooth wear

• Tooth pain or sensitivity

• Fracture of the restoration of the opposing tooth

• Widening of the PDL

• Interferences in the movement of the TMJ and muscles of mastication

Evaluation of occlusion

• Dry the tooth

• Use articulating paper

• Reduce marks

• Recheck centric occlusion and continue removing marks

• Check excursive contacts and remove

• Wipe the remaining marks off

Exceptions to the evaluation of occlusion

• Restoring with a sedative temporarily because you don’t want the patient applying more pressure

• When restoring the incisal edge

Obtundant properties

Soothing properties

• Eugenol/Zinc Oxide/IRM/ZOE

• For a hot (painful) tooth

Abfracture

Loss of tooth surface at the cervical areas caused by tensile and compression forces during tooth flexure (bending)

• It can be v-notch

Crossbite

Lower teeth are buccally/labially to upper teeth (posterior/anterior)

Class I occlusion

Neutro-occlusion: The mesiobuccal cusp of the maxillary first molar lies on the mesiobuccal groove of the mandibular first molar

• Straight profile

Class I occlusion

Disto-occlusion: The mandibular first molar is distal to the mesial buccal cusp of the maxillary first molar

• Convex profile

• Overbite

Class III occlusion

Mesio-occlusion: The mesiobuccal groove of the mandbular first molar is mesial to the mesiobuccal cusp of the maxillary first molar

• Underbite

• Concave profile

Operator’s position

• Thighs should be parallel to the floor with feet flat on the foor

• Patient should be positioned at HEART HEIGHT

• FOCAL LENGTH SHOULD BE 12-14 INCHES AWAY FROM PATIENT

Operator’s position

Right handed: 8-12 o clock

Left handed: 4-14 o clock

Modified pen grasp

Instrument is held near the junction of the handle and shank (first finger and thumb)

• The grasp should be firm, yet not rigid, to allow for maximal maneuverability of the instrument while minimizing hand fatigue

Fulcrum

Is a point of rest on which the fingers are stabilized and can pivot from and to activate the instrument and obtain the best position or adaptation (hard tissue)

Adaptation

The relationship between the working end of the instrument and the tooth surface

Incipient caries

Beginning of caries

• Most commonly seen on occlusal surfaces (pits/grooves), interproximal surfaces

• Can be reversed

Rampant caries

Rapidly spread caries

Recurrent caries

Caries that reoccur under previous restoration

Arrested caries

Non-active caries, static

Steps to reduce caries

• Reducing the number of bacteria through plaque removal and limiting the food supply

• Increasing the host resistance (by strengthening the tooth with fluorides)

Dental caries causative factors

• Geographic environment

• Systemic health

• Race and sex

• Heredity

• Tooth chemical and structural characteristics

• Saliva

Class I cavity

Cavities beginning in the pits and fissures that occur in:

• Occlusion of premolars and molars

• Occlusal two-thirds of the facial area of the mandibular molars

• Occlusal third of maxillary molars

• Lingual of incisors

Class II cavity

Affects the proximal surfaces of premolars and molars

• MO, DO, MOD

Class III cavity

Affects the proximal surfaces of incisors and canines (anterior teeth only)

• No incisal involvement

Class IV cavity

Involves the proximal surfaces of incisors and canines, but also extends to the incisal angle

Class V cavity

Occurs on the cervical third of the facial or lingual surfaces of any tooth

Class VI Cavity

Involves defects of abrasion on the incisal edges of anterior teeth and occlusal surfaces of posterior teeth

Wall

Vertical or horizontal surface within the preparation named for the surfaces toward which they face, or for a structure it approximates