Wednesday, December 25, 2019

Class III jaw relation in edentulous PT.. Affect esthetic and arrangement of maxillary denture



Class III jaw relation in edentulous PT:
a- It will affect size of maxillary teeth.
b- Affect retention of lower denture.
c- Affect esthetic and arrangement of maxillary denture.
d- All of the above.***
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Abstract:
Further to some reminders concerning terminology and resorption, this article presents the full denture prosthetic treatment for two patients with total edentation and a prognathic malocclusion.
The first case presents a tridimensional symptomatology, described by: a progeny; a voluminous mandibular terrain; a concave profile; a rather closed mandibular angle; a mandible ridge which circumscribes the upper jaw; The particularities of the prosthetic treatment in this case are: a lowering of the posterior occlusal plane; a mounting of the teeth in a limited external position, that is to say, the maxillary lingual cuspids and the mandibular mesio-distal groove on the inter-crest line; the mandibular incisors and cuspids placed with a lingual inclination to obtain an edge-to-edge occlusal contact.
The second case is of vertical symptomatology type, described by: a macrogeny; a moderate concavity of the profile; a very marked increase of the vertical dimension; an open mandibular angle; a short ramus; a long mandibule; a very marked overjet between the anterior crests.
The particularities of the prosthetic treatment for this case are: a posterior teeth placement, avoiding cross-bite position, taken into account the strong convergence of the intercrest lines; a strong lingual inclination of the mandibular incisors and cuspids, in order to obtain an edge-to-edge occlusal contact.
In the light of these two specific cases, emphasis is placed on the particularities of the treatment and on the teeth placement proposed in order to avoid any cross-bite teeth mounting.
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The maxilla is an even bone (formerly upper maxillary bone), participating in the facial mass. It is the largest bone of the facial mass. They enter into the constitution of the walls of the nasal cavity, orbital cavities and the oral cavity; they carry the teeth of the upper jaw.
They consist of a hollow body of a maxillary sinus and a frontal process.
On the median line: the nasal incision, of pyramidal shape, which carries the cartilage of the nose.
The two maxillaries articulate with each other to form the upper dental arch and the bony palate. All the bones of the face attach or articulate with the maxillary and make the central bone of the face. These two bones are the ones that carry the teeth.
The skeleton of the face is located at the lower and anterior part of the skull. It is divided into two parts called jaws: the upper jaw and the lower jaw.
The upper jaw consists of 13 bones. Only one is odd, it is the vomer; the others are even and lateral and arranged symmetrically on both sides of the median line. These bones are: the upper jaws, the unguis, the palatines, the lower turbinates, the clean bones of the nose and the malar bones.
The lower jaw is made of a single bone, sometimes referred to as the mandible.

The upper maxillary:
The maxilla is the most important of all the bones of the upper jaw, it is an even bone, located in the central part of the face.
The maxilla is located above the oral cavity, below the orbital cavity, outside the nasal cavity. He takes part in the formation of the walls of these three cavities.
It provides the upper teeth with their implantation surfaces and enters into the constitution of the main regions and cavities of the face, palatal vault, nasal fossae, orbital cavities, zygomatic pits, pterygo-maxillary fossae.
On the descriptive plane, the maxillary superior, fairly regularly quadrilateral and slightly flattened from inside to outside, can be described two faces, one internal, the other external, four edges and four angles.
If the maxillary is relatively large, it is light because of the existence of a cavity, the maxillary sinus, which occupies the upper two-thirds of the thickness of the bone.
We can describe to him, an external face, an internal face and 4 edges

The external face:
In its lower part the outer face has vertical projections in relation to the shape of the teeth. Some are more marked as the canine hump that responds to the root of the canine. Inside this hump, there is a vertical depression, the myrtle fossa into which the muscle of the same name is inserted. It is not uncommon to see the myrectic fossa subdivided into two secondary dimples by a small ridge that responds to the lateral incisor.

Pyramidal or malar apophysis of the maxilla:
Beyond the canine fossa, and above the projections which correspond to the dental roots, the external surface of the maxillary is entirely occupied by a strong transverse projection, affecting the form of a pyramid with triangular base, presenting three faces, three edges, and a vertex.
1- the upper or orbital surface It is flat and regularly smooth, it constitutes a large part of the floor of the orbit. It is tilted slightly "so that it looks upwards, forwards and outwards". "From the middle part of the posterior border a gutter extends, the suborbital gutter, which runs forwards, below and slightly inwards, and continues through the suborbital canal. In the gutter, the canal and the suborbital hole, pass the nerve and the suborbital vessels. The upper wall of the suborbital canal thickens from back to front. It is formed by the welding of the two lips of the gutter which precedes the canal in its development. From this meeting results the formation of a suture of which there are often vestiges in the adult. From the inferior wall of the suborbital canal, and at an average of 5 millimeters behind the suborbital space, a narrow canaliculus, the anterior and superior dental canal, is detached. This canal runs downwards, through the bony wall, and delivers passage to the anterior dental vessels and nerve for the canine and incisors on the same side."
2- The anterior or genial aspect corresponds with the soft parts of the cheek. It presents a large orifice, the suborbital hole, where the preceding canal terminates. This orifice "is situated about 5 or 6 millimeters below the lower edge of the orbit, at the union of its internal third and middle third, about 3 centimeters from the median line, and, consequently, the lowered vertical of the supraorbital cleft. "
"This hole is continued to the anterior surface of the bone by a shallow gutter, obliquely directed downwards and inwards. Below the orbital hole and the gutter that follows, is a depression, the canine fossa, where the canine muscle is born. From the anterior portion of the sub-orbital canal by a small duct, which is carried downwards towards the dental cells, constantly following the thickness of the osseous wall: this is the anterior dental canal. As the name suggests, it houses the anterior nerve, the collateral branch of the suborbital nerve.
3- The posterior or zygomatic face "forms the anterior wall of the pterygo-maxillary fossa and its background. It is slightly convex in its internal part and becomes concave transversely, "outside, near the malar bone". "The convex, prominent internal part is called the tuberosity of the maxilla. On this face are noted some vertical gutters, and several orifices: these are the posterior dental holes through which the posterior dental nerves and the branches of the alveolar artery pass. The posterior surface of the tuberosity is hollowed, at the top, near the upper edge, of a transverse gutter, the depth of which increases from inside to outside to the posterior end of the suborbital gutter. This gutter responds to the upper maxillary nerve. "

Edges:
The pyramidal process has three edges:
1- The lower edge, concave and foam, goes vertically downwards, towards the first big molar. This edge separates the anterior face of the zygomatic face.
2- The anterior edge constitutes the lower and internal portion of the orbital rim; it is below this border that the suborbital canal passes, and in this canal, the nerve and the suborbital vessels.
3- Finally, the posterior border, rounded and foamy, corresponds to the great wing of the sphenoid, from which it remains separated by a slit which runs along the inferior and external angle of the orbit; it is the sphenomaxillary fissure.

The base:
The base of the pyramidal process occupies in height the upper three quarters of the outer surface of the maxilla.