Occlusion in joint prosthesis
It occurs during the three stages: pre-prosthetics, prosthetics and post-prosthetics.
Remember
It contributes to the stability of the elements constituting the dental apparatus (its respect preserves everything that remains after tooth loss).
It contributes to the patient’s comfort
It contributes to the stability of the prosthesis
Dental occlusion: study of the meshing of teeth when they are in contact, its respect is essential to avoid joint problems, SADAM…
- Occlusal schema : set of factors which characterize the different inter-arch relationships or relations within the framework of an occlusal concept, all occlusal schemas are governed by the static and dynamic cusp relationships.
- Optimal occlusion : occlusion which requires the least effort of adaptation, neuro-muscular-articular, to satisfy this requirement certain criteria must be respected.
Occlusion in joint prosthesis
Its characteristics:
Tripod dento-dental contact
Relationship centered corresponds exactly to the PIM
Perfect functional anterior guide
Dento-dental contact cusp-fossa “in PIM” (cusp-cusp contact is false)
Canine protection or group protection
Occlusal forces directed along the long axis of the tooth
….. ! must not cause dental displacement with the prosthetic restoration
Harmony of the stomatognathic system
Stable occlusal relationships of the RC ==) PIM or Laterality
Coincidence between RC and PIM
Immediate disocclusion of the posterior teeth on the non-working side for laterality and for the posterior part of the propulsion mvm
The DV must allow a resting position with a free space for physiological inclusion
Initial contact should be made through a multitude of contact points rather than a large contact surface
Absence of interference and absence of prematurity…
Different occlusal concepts in joint prosthetics
- Concept of canine function: it is indicated when the conditions concerning the canine are favorable (anatomical crown, no abrasion, good condition, absence of caries ==) favorable extrinsic and intrinsic values.
Indicated whenever the periodontal support of the canine is resistant
Characterized by:
contacts between the canines (working side) with disocclusion on all the other teeth
PIM cusp fossa reports with coincidence between ICM and RC
in propulsion anterior contact + posterior disocclusion
in deduction a canine function on the working side + disocclusion on the non-working side.
Occlusion in joint prosthesis
- Group function concept: indicated when
the incisal coverage is weak (end to end…
a weakened canine support
periodontal complex requires good distribution of occlusal forces
(to relieve the canine because it is weakened)
Characterized by:
Marginal cusp-crest ratio
PIM does not coincide with RC, but slightly earlier than it (0.3 – 1.3mm)
Tolerates movement without increasing DV
In propulsion, extended anterior contact + disocclusion on the posterior side
In laterality group function on the working side + no contact on the non-working side
- Balanced occlusion/mutually protected occlusion/organic occlusion:
The ant teeth protect the cuspid teeth during all movements, in PIM the post teeth protect the ant teeth; which are in very light exclusion 25 microns
(the ant teeth protect the post teeth during a movement, during another mvm it is the opposite)
It joins the concept of canine occlusion and is characterized by:
The ant teeth protect the cuspid teeth during all mandibular excursions (right, left or propulsion laterality)
(In propulsion for example there will be anterior contacts with posterior contacts which will absorb part of the occlusal loads to relieve, help the anterior teeth, we try not to have generalized contacts but rather with the most posterior teeth the 7 for example “a tripod contact on the arch not on the tooth” if not we make a generalized contact if we cannot
Determinants of occlusion
Anatomical determinants:
ATM
Anterior guide: palatal concavity of the upper IC group, by incisal overlap, incisal overjet, arch shape
Occlusal plane: contact surface between the 2 arches
Curve of spee: sagittal which must present a slight post concavity
Condylar trajectory:
Wilson’s curve: frontal passes through the vestibular and palatal cusps of the pm+m
Neuro-muscular determinants: muscles, nervous systems, etc.
Mand reference positions:
RC: mandibulo-cranial reference position, physiological, the highest and most anterior of the condylo-disco-temporal articular contacts, it favors the relationship of the condyles according to a hinge axis, this is when the condyles occupy the highest and most rearward position in the glenoid cavity, from this position the mandible can perform any movement.
PIM: dental reference position determines the situation of the mandible when the max and mand teeth establish a maximum of contact between them. This occlusion position in pim can preexist with condyles in RC, in this case we speak of occlusion in centered relation (8% of population)
CLOSING PATH:
OCCLUSAL ANATOMY:
Group IC: free edge + canine tip
Group pm+m; table or occlusal surface formed by the internal sides of the vest and ling/palatine cusps, there are also the marginal ridges as well as pits and dimples.
Occlusion in joint prosthesis
The physiology of occlusion
Angle classes
- cusps supports: upper palatine and lower vest. their role: it maintains the occlusion dv ==) if abrasion: dv will decrease
It is subdivided into 3 groups: 2 in the mandible and 1 group
The 1st mand group: the vest cusps of the pm+m inf, they are the most important to ensure the stability of the occlusion in PIM, the support points of the 1st group articulate mainly with the upper marginal ridges
2nd group: the free IC edges which come to rest on the palatal faces of the upper IC palatal faces, in class 1 angle the laterals and lower canines articulate with 2 upper teeth (ratio 1/2) on the other hand the lower centrals only rest on the upper centrals
3rd group: palatal cusps pm + m max
- Guiding cusps: they guide the mvm mand and help to free the cheeks and lips
Examination of occlusal contacts in retrusion: from the PIM position the mand can perform retraction mvm while maintaining the dento-dental contact “retrusion” this position of contact in centered relation is most often located the most rear of the PIM.
This sliding is extended to the extent that the occlusal surfaces of several teeth participate in the mvm especially
If the 1st contact in RC is located on a single tooth ==) prematurity
Look for CR in the absence of any muscle spasm, the patient must be heard, he is asked to open his mouth wide by placing his thumbs in front of the vestibular surfaces of the lower molars without exerting pressure, after 30 seconds he is asked to close it firmly while guiding the hand into the CR position
Examination of occlusal contacts in protrusion: presents the path that the jaw can take when the lower I slide on the palatal faces of the upper I from the PIM to the end to the end
The surface extending from the occlusion support points in PIM to the free edge constitutes the anterior guidance.
If a tooth comes into contact with only one tooth == obstacle which can cause deviations..
Interferences: during mvm
Prematurity: RC/static PIM
Ideal occupancy
Balanced/dysfunctional convenience occlusion compensated for jouffrion??!!!
Convenience occlusion unbalanced pathogenic / dysfunctional decompensated DE JOURKING!!
Clinical application
Pre-clinical: 2 possibilities
- Patient without
Prosthetic ..
Good oral hygiene Regular scaling at the dentist Dental implant placement Dental x-rays Teeth whitening A visit to the dentist The dentist uses local anesthesia to minimize pain