occlusion

when the jaws are closed and stationary and the teeth are in contact, what is this termed as?

static occlusion

what is dynamic occlusion?

it refers to to occlusal contacts made when the the jaw is moving. during chewing, there is no tooth contact between the teeth on the chewing side of the mouth

what is occlusion?

it means “closing up.” the contact relationship of the upper and lower during various activities of the mandible (mastication, swallowing and speech) in functional and nonfunctional positions

what is centric occlusion?

the relation of the upper and lower teeth when they are at maximum intercuspation, such as during swallowing or in the terminal position of the masticatory stroke. it is a tooth to tooth relation

what does occlusion refer to?

it is not only referring to the contact between the teeth, but also to all the factors concerend with

what are the components of human dental occlusion?

1. the teeth and their investing tissue

2. the jaws

3. the temporomandibular joint

4. muscles of mastication

what teeth serve as the key of occlusion?

the maxillary and mandibular first molars

why do permanent first molars serve as the key of occlusion?

they are the first permanent teeth to develop and erupt in the oral cavity, they occupy a central anteroposterior position in the jaw, their positions are guided by the presence of the deciduous molars preceding them, and their eruption is not disrupted as they have no predecessors.

why is the maxillary first permanent molar more accurate than the mandibular first permanent molar?

it is attached to a bone fixed to the base of the skull

where does the maxillary 1st permanent molar occlude?

the mesiobuccal cusp of the upper 1st molar occludes in the mesiobuccal groove of the lower 1st molar, and is known as the key of occlusion

what are the 3 classes of Angle’s classification?

• class I, which is normal and standard

• class II, which is malocclusion. it is retrognathic

  • retruded profile (chin is recessed)

  • deficient chin length

• class III, which is another malocclusion. it is prognathic

  • protruded profile (chin is excessively protruded)

  • excessive chin length

how is class I molar relationship of angle’s classification described as?

the mesiobuccal cusp of the upper 1st permanent molar occludes in the mesiobuccal groove of the lower 1st permanent molar, known as the standard relationship, key of occlusion

how is class II molar relationship of angle’s classification described as?

malocclusion with a retrognathic profile. the mesiobuccal cusp of the upper 1st permanent molar occludes anterior to the mesiobuccal groove of the lower 1st permanent molar, leading to a recessed chin

how is class III molar relationship of angle’s classification described as?

malocclusion with a prognathic profile. the mesiobuccal cusp of the upper 1st permanent molar occludes posteriorly to the mesiobuccal groove of the lower 1st permanent molar, leading to a protruded chin

what is centric relation?

the position of the mandible in which the condyles are resting in the uppermost, unstrained position in the glenoid fossae and related anteriorly to the distal slope of the articular eminence. It is a bone-to-bone relationship.

what are the types of cusps?

1. centric cusps

2. non-centric cusps

what are centric cusps?

the buccal cusps of the mandibular posterior teeth and the lingual cusps of the maxillary posterior teeth are centric or supporting cusps. these cusps play a major role in mastication and maintaining dimensions between the maxilla and the mandible

what are non-centric cusps?

buccal cusps of the maxillary posterior teeth and the lingual cusps of the mandibular posterior teeth. they are also known as the shearing or guiding cusps. they are responsible for the shearing of food, which minimizes food impingement (food impaction)

what is the curve of spree?

it refers to the anteroposterior curvature of the occlusal surfaces, beginning at the tip of the mandibular cuspids and following the cusp tips of the bicuspids and molars, continuing as an arc through the condyles. If extended, this curve would form a circle with a diameter of about 4 inches.

what is the curve of wilson?

the mediolateral curve formed by the buccal and lingual cusp tips of the mandibular posterior teeth on each side of the arch.

what is an overjet?

horizontal relation of the upper teeth to the lower teeth in centric occlusion. it increases the duration of the occlusal contact in protrusive and lateral movements in incision and mastication

what is an overbite?

the vertical relation of the upper teeth to the lower teeth in centric occlusion. it increases the efficiency of the anterior teeth in biting

what is the importance of overbites and overjets when they are minor?

they prevent soft tissue biting, as well as guiding the mandible through various lateral movements

what are intercuspal relations like for the incisal ridges of mandibular anterior teeth?

they make contact with the lingual surfaces of the maxillary anterior teeth

what are intercuspal relations like for the maxillary posterior teeth?

• the buccal cusps of the maxillary teeth overlap the buccal cusps of the mandibular posterior teeth.

• the lingual cusps of the maxillary teeth occlude in the fossae and central grooves of their mandibular counterparts.

what are intercuspal relations like for the mandibular posterior teeth?

• the buccal cusps occlude in the central grooves and fossae of the opposing maxillary teeth.

• the lingual cusps are positioned lingual to the upper lingual cusps.

how many subdivisions does class II of angle’s classification contain?

1. division 1 and its subdivision

2. division 2 and its subdivision

how many subdivisions does class III of angle’s classification contain?

1. class III

2. pseudo class III

3. subdivision

4. skeletal class III