Occlusion 1 Flashcards
what is the SIMPLE definition of occlusion?
the contacting of occlusal and incising surfaces of opposing maxillary and mandibular teeth
what is the GPT 8th ed definition of occlusion?
the static relationship between the incising or masticating surfaces of the maxillary or mandibular teeth or tooth analogues
what is the REALISTIC definition of occlusion?
The dynamic morphological and physiologic relationships among all components of the masticatory system including the neuro-musculature, TMJs and teeth
what is the importance of occlusion?
- Essential to both general and dental health
- Mastication
- Ability to speak
- Enjoy food
- Aesthetics
what is the history of occlusion?
- Since the 1800’s occlusal concepts/theories have come and gone.
- Most occlusal concepts are based in part on theory, and all of these theories borrow in part from the past
what is maximum intercuspal position (MIP)?
The complete intercuspation of the opposing teeth independent of condylar position
what is centric occlusion?
The occlusion of opposing teeth when the mandible is in centric relation; this may or may not coincide with the maximal intercuspal position
what is centric relation?
a physiologic position of the condyle-disc
assemblies that occurs naturally when the masticatory musculature functions in a coordinated manner
how does centric relations relate to prosthodontics?
until the position and condition of the temporomandibular joints are precisely determined, an accurate maxillomandibular relationship cannot be verified
what is the current definition of centric relation in the CPT 9?
is a maxillomandibular relationship, independent of tooth contact, in which the condyles articulate in the anterior-superior position against the posterior slopes of the articular eminences
what is the most important thing to understand about centric relation?
it should be a posterior position that is unstrained and repeatable. We can help guide a patient but should never force the mandible in a posterior direction.
With loss and/or wear of teeth the mandible tends to take a protrusive posture.
what is overload and when may it happen?
When teeth interfere with centric relation and/or maximal intercuspation they may then be subject to overload
Occlusal trauma may result, with excessive wear, mobility, sensitivity or pain, and fractured cusps. Additionally, there will be an increase in nociceptor and proprioceptor signals that effect neuromusculature control, which may attempt to “reroute” mandibular closure
which arch is usually larger and what shape are arch forms generally ?
maxillary is slightly larger
arches may be square, ovoid and tapering
what roles do arch configuration, tooth size and shape play?
- esthetics
- phonetics
- mastication/deglutition
- para-functional bruxism
The ________ posterior teeth have a horizontal overlap on the buccal aspect, while the _______ posterior teeth have a horizontal overlap on the lingual aspect. Adequate horizontal overlap of each reduces the potential for _______ and _______
maxillary, mandibular, cheek, tongue biting
The occlusal plane is generally elevated _______ relative to the natural horizontal plane (when the patient is standing) by approximately 8 to 10 degree
antero-posteriorly
Typically, the maxillary incisal edges show from ______ mm at the resting lip length with the free gingival margin showing at a high smile
0 to 2
The incisors are generally aligned with the patient’s________, although variations are common due to tooth loss, tooth size-arch length discrepancies, mesial drift, tooth agenesis and tooth wear/altered eruption patterns
facial midline
what is the definition of plane of occlusion?
refers to an imaginary surface that theoretically touches the incisal edges of the incisors and the tips of the occluding surface es of the posterior teeth
what is the significance of plane of occlusion?
a flat occlusal plane will not allow simultaneous contact in more than one area of the dental arch. That is why the occlusal plane is usually curved.
what is the definition of Vertical Dimension of Occlusion (VDO or OVD)
The distance between two selected anatomic or marked points (usually one on the tip of the nose and the other on the chin) when in maximal intercuspal position
what is the definition of Rest Vertical Dimension (RVD)
The postural position of the mandible when an individual is resting comfortably in an upright position and the associated muscles are in a state of minimal contractual activity
what is interocclusal distance?
The distance between the occluding surfaces of the maxillary and mandibular teeth when the mandible is in a specified position
what is interocclusal rest difference?
the difference between the rest vertical dimension and the occlusal vertical dimension. (was called Freeway Space)
RVD – OVD = IRD
teeth do not usually conform to a ________
flat plane
what is the curve of spee?
when viewed from the lateral aspect the incisal and cusp edges follow a curve which curves upwards from anterior to posterior
what is Monson’s (Wilson’s) curve?
when viewed from the coronal plane there is a curve in the posterior region which is concave and the cusps of the right and left side teeth lie on this curve
what is the significance of the curve of spee?
- this anterior-posterior curve results in the alignment of each tooth for the maximum resistance to the functional loading.
- The long axis of each lower tooth is aligned nearly parallel to its individual arc of closure around the condylar axis.
- The relationship between the Curve of Spee and the condylar axis relates to the condylar path of protrusion.
- If the curve is one that passes through the condyle, the posterior teeth will be discluded by the normal condylar path on its steeper condylar eminence.
what is the significance of the curve of Wilson?
- The axial inclination of the posterior teeth is nearly parallel with the inward pull of the lateral pterygoid muscles.
- When the teeth are aligned with the principle direction of the muscle contraction, it produces the greatest resistance to masticatory forces
what is masticatory function?
the inward inclination of the lower occlusal table is designed for direct access of food from the lingual, with no blockage by lower cusp by the action of the tongue
Edward Angle postulated that the _______ were the key to occlusion
maxillary first molars
what are the three classifications of occlusion?
class I, class II (division 1 and division 2), class III
define what class I occlusion is
- Profile of skeletal class I is normal
- Where the mesiobuccal cusp of the maxillary first molar is aligned directly over the mesiobuccal groove on the mandibular first molar.
- Incisal edges of maxillary teeth are labial to the incisal edges of the mandibular teeth. Incisal margins of the mandibular incisors occlude with or directly lie below the
palatal surfaces of the maxillary incisors
define what class II occlusion is
- In the skeletal relationship, it seems that the mandible is small compared to the maxillae.
- Mandibular teeth are distal to their normal maxillary teeth. Occludes at least half a cusp more mesial to the mandibular first permanent molar.
- Abnormally large overlap of maxillary incisors over mandibular. Incisal margins of the mandibular incisors lie behind the cingulum plateau on the palatal surfaces of the maxillary incisors.
what is the difference between class II division I and division II?
division I MAXILLARY incisors have a labial inclination (proclined)
division II MAXILLARY incisors have lingual inclination (retroclined)
** look at slide 31 in occlusion I
define what class III occlusion is
- Large mandible compared to the maxillae
- Lower anterior incisors are in edge to edge or labial to upper anteriors. Incisal margins of the mandibular incisors lie in front of the cingulum plateau on the palatal surfaces of the maxillary incisors.
- Mandibular molars are mesial to the class I relationship. Maxillary first permanent molars occludes at least half a cusp more distal to the mandibular first permanent molars than the standard anatomical position.
look at slides 33-36 for references on class I, II and II
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