Azer

Question 1

what is prosthodontics?

Answer 1

dental specialty that deals with restoring missing oral and paraoral structures

Question 2

mandibular movements in sagittal plane

Answer 2

rotation and translation

Question 3

where does rotation occur around?

Answer 3

terminal hinge axis or transverse horizontal axis (THA)- imaginary line connecting the centers of the two condyles

Question 4

what distance is rotational movement limited to?

Answer 4

20-25mm of incisal separation before the mandible start to translate

Question 5

mandibular movements in horizontal plane

Answer 5

whole mandible- straight protrusive

lateral movement of mandible

Question 6

what happens in lateral movement of the mandible?

Answer 6

non-working condyle travels forward and medial

working condyle exhibits slight lateral translation (bennett movement)- may be slightly forward or backward

Question 7

mandibular movements in frontal plane

Answer 7

straight protrusive movement- both condyles move downward as they slide along the eminences.
lateral movements- non-working condyle will move downward and medial
working condyle- rotate and move lateral and upward or lateral and downward

Question 8

range of mandibular movements

Answer 8

envelope of motion

Question 9

what is centric relation arc of closure?

Answer 9

when mandible is guided to centric relation, the arc traced by the point between 2 mandibular centralincisors

Question 10

when is mandible in centric relation?

Answer 10

at any point along the centric relation arc of closure

Question 11

what is the definition of centric relation?

Answer 11

maxillomandibular relationship in which the condyles articulate with the thinnest avascular portion of their respective discks, with the complex in the anterior-superior position against the shapes of the articular eminencies. this position is independent of tooth contact. restricted to a purely rotary movement about the transverse horizontal axis

Question 12

centric occlusion

Answer 12

if mandible is manipulated upward on the centric relation arc of closure until tooth contact occurs

Question 13

what happens to 90% of the population?

Answer 13

co contact occurs between only one or two maxillary and mandibular teeth.

Question 14

what are contacts points referred to as?

Answer 14

initial points of contact

contacting surfaces located on distal incline of the mandibular tooth and mesial inclines of maxillary teeth

Question 15

what happens if the mandible closes further past centric occlusion?

Answer 15

it must slide out of CR along a path dictated by the inclines of the contacting posterior teeth. mandible continues to close and slide forward or laterally until all the teeth intercuspate together as best as they can.
reaches maximal intercuspation (MI)

Question 16

what is centric slide? what is its significance?

Answer 16

slide btween CO and MI. if initial point of contact (CO) coincides with MI, restorative treatment is made relatively easy. if there is a slide- it is necessary to determine whether corrective occlusal therapy is needed before restoreative treatment is accomplished

Question 17

what is protrusive movement?

Answer 17

starting from MI position, the mandible can be protruded keeping tooth contact. mandible has to open as mandibular anterior teeth ride down along the lingual concavity of the maxillary anterior teeth until they reach an end to end position.
tracing on sagittal plane is dictated by the shape and position of the maxillary anterior teeth (vertical and horizontal overlap)
as the mandible continues to move forward and the anterior teeth clear, the contacting posterior teeth dictates its path. the mandible continues to close and slide forward until maximum protrusive superior position is reached. from thiss position, the mandible can undergo a wide opening movement to its max opened position. max opening may range up to 50-60mm measured between maxillary and mandibular incisors. the mandible can now close back with translation and rotation to its centric relation arc of closure.

Question 18

habitual arc of closure

Answer 18

patient is instructed to close patient close mouth from the maximum open position. line not reproducible because it is not a border position.

Question 19

are border movements of the mandible reproducible?

Answer 19

yes

Question 20

where is the physiologic rest position?

Answer 20

lies on habitual arc of closure. the position that the mandible assumes when all muscles are at a state of equal relaxation. characterized by the teeth being separated by the interocclusal rest distance or space

Question 21

how is the interocclusal rest distance or space determined?

Answer 21

using two arbitrary reference points on each side of the maxlliary and mandibular teeth or attached gingiva or the skin over the mandible and cranium. distance between these two reference points with the teeth in MI is the vertical dimension of occlusion (VDO). the distance between these two points with the mandible in physiologic rest position is the vertical dimension at rest (VDR)
interocclusal rest distance=VDR-VDO

Question 22

what is incisal guidance?

Answer 22

resultant protrusive path the lower incisors must follow due to anterior teeth contact. it is determined by the lingual concavities of the maxillary anterior teeth as well as vertical and horizontal overlap of maxillary and mandibular anterior teeth

Question 23

how is the term incisal guidance widely used?

Answer 23

not only to define the resultant protrusive path of the mandibular incisors but also the path they must follow during lateral jaw movements

Question 24

when is canine guidance used?

Answer 24

if relationship of the maxillary and mandibular canines determines the lateral jaw movement, the term canine guidance can be used but only in reference to the path during lateral movement

Question 25

how is incisal guidance measured?

Answer 25

in degrees from horizontal plane

Question 26

what does incisal guidance determine?

Answer 26

the amount the mandible must drop in the anterior region

Question 27

what is determined by the angle of articular eminence?

Answer 27

the amount the mandible must drop in the posterior region

Question 28

what are the posterior determinantsof mandibular movements?

Answer 28

inclination of articular eminence medial wall of glnoid fossa intercondylar distance

Question 29

what are the anterior determinants of mandibular movement?

Answer 29

horizontal overlap of anterior teeth | vertical overlap of anterior teeth

Question 30

what are the other determinants of mandibular movement?

Answer 30

occlusal plane curve of spee neuromuscular response

Question 31

articulators

Answer 31

mechanical devices that can simulate mandibular movements

Question 32

small non-adjustable articulators

Answer 32

often lead to restorations with occlusal discrepancies as they cannot reproduce the full range of mandibular movements

Question 33

semi-adjustable articulators

Answer 33

about the same size as the anatomic structures that they represent. using a facebow transfer, articulated casts can be positioned with sufficient accuracy that will minimize the need for clinical adjustment during treatment

Question 34

fully adjustable articulators

Answer 34

instruments have a wide range of positions and can be set to follow the patient's border movements

Question 35

what is a pantograph?

Answer 35

device that is used in conjunction with fully adjustable articulators to adjust the condylar elements to follow the tracings obtained intraorally

Question 36

what are articulators that have the condyles connected to the lower member?

Answer 36

arcon articulator

Question 37

what are articulators with condyles connected to their upper members?

Answer 37

non-arcon articulator

Question 38

what is the choice of an articulator based on?

Answer 38

the understanding of the biomechanical principles of occlusion which will result in a more efficient use of time and effor and deliver quality clinical results

Question 39

what is the ear bow transfer?

Answer 39

the means you record from the patient the exact anatomical relation of the maxillary dental arch via imprints of teeth to the patients intercondylar axis. record is then used to mount maxillary cast on articulator and then mandibular cast is related to maxillary cast and mounted using centric relation record obtained from the patient

Question 40

what are the significances of the ear bow transfer?

Answer 40

relates the maxillary cast (occlusal surface) to the terminal hinge axis orients the maxillary cast (long axes of teeth) correctly in space using a third point of reference. important for extensive anterior restorations is aligned parallel to the interpupillary line (horizontal reference) permits mounting of the maxillary cast on a semi-adjustable articulator allows the mandibular cast to be correctly mounted using a centric relation (CR) record

Question 41

how to record mandible's path of vertical movement in terminal hinge position?

Answer 41

all proprioceptive impulses that direct mandibular movements have to be blocked out impulses are responsible for awareness of mandibular position in space and guide the mandible in its habitual movements. a natural reflex action of the mandible is to close into a lateral or a lateral protruded position when something is introduced in the mouth as as wax and the patient is instructed to bite. there fore the relationship of the mandible to the maxilla in the terminal hinge position should be obtained without tooth contact

Question 42

methods for recording centric relation

Answer 42

chin point guidance anterior deprogrammer bilateral (bimanual) manipulation

Question 43

requirements of centric relation record

Answer 43

along the arc of rotation of the mandible no teeth touching thin soft fast setting dimensionally stable easily verifiable in the mouth and on the mounted casts

Question 44

what are the uses of diagnostic casts?

Answer 44

diagnostic casts that are correctly mounted in CR on a semi-adjustable articulator using a face-bow transfer, provide valuable info for fixed prosthodontic work. they are generally used for diagnosis and treatment planning as well as construction of diagnostic wax-ups. in addition, diagnostic casts are used to fabricate custom trays and provisional restorations

Question 45

what is occlusal equilibration?

Answer 45

correction of stressful occlusal contacts through selective grinding. it involves the selective reshaping of tooth surfaces that interfere with normal harmonious jaw function

Question 46

is leaving malocclusion worse than poor equilibration?

Answer 46

no may produce new interferences that the patient must learn to cope wih proprioception of new interferences can create an occlusal awareness and can trigger extreme discomfort of the teeth, tmjs, and masticatory muscles.

Question 47

what is mutually protected occlusion?

Answer 47

in maximum intercuspal position, posterior teeth come into contact and act as stops to minimize horizontal load on anterior teeth anterior teeth guide excursive movements of the mandible so that no posterior teeth tooth contact occurs during lateral or protrusive excursions

Question 48

is posterior tooth contacts that disclude anterior teeth during lateral excursive movements harmful?

Answer 48

yes interferences can alter muscular patterns during lateral movements, as well as create primary occlusal trauma, fremitus, and increase the likelihood of tooth fracture and development of wear facets. may result in unfavorable loading of the TMJs.

Question 49

what are occlusal treatment goals?

Answer 49

to direct occlusal forces along the long axes of teeth (stable posterior contacts) in MI, all mandibular teeth should contact their maxillary opponents at the same time and with the same intensity i.e. centric occlusion (CO) should be coincident with MI to furnish a smooth protrusive path guided by anterior teeth without any interference from occlusal contacts between posterior teeth working side contacts, whether canine protected or group function, should not be prevented from contacting by non working side interferences

Question 50

what is incisal guidance?

Answer 50

immediate disclusion of posterior teeth takes place on mandibular protrusion

Question 51

what is canine guidance?

Answer 51

immediate disclusion of posterior teeth takes place as soon as the lateral movement begins

Question 52

what is group function?

Answer 52

the mandibular buccal working cusps travel downward, forward, and lateral in contact with the lingual inclines of the maxillary buccal cusps, simultaneously with the canine

Question 53

what are equilibration procedures?

Answer 53

reduction of all contacting tooth surfaces that interfere with terminal hinge axis closure (centric relation) selective reduction of tooth structure that interferes with lateral excursions elimination of all posterior tooth structure that interferes with protrusive excursions harmonization of anterior guidance