TOTAL UNIMAXILLARY ADJOINING PROSTHESIS
- INTRODUCTION
The production of a complete removable unimaxillary prosthesis opposed to a partially or totally dentate arch poses many difficulties. First of all, there is a difference in support between the two arches, causing excessive forces transmitted to the edentulous ridge, which can lead to a certain number of harmful consequences such as injuries under the prosthesis, fractures of the complete removable prosthesis, excessive resorption of the edentulous ridge followed by prosthetic instability.
Occlusal rehabilitation through a. Complete Unimaxillary Upper PA in relation to a mandibular dentate arch requires a thorough analysis of the occlusal plane and imperative correction of the latter’s disturbances by remodeling the occlusal surface of the antagonist arch. The morphology, nature, and position of the remaining teeth limit and complicate the choice of prosthetic teeth and that of the assembly.
II- TOTAL UNIMAXILLARY EDENTATION OPPOSED TO COMPLETE NATURAL EDENTATION.
A: GENERAL DIAGNOSIS ELEMENTS:
- SEX:
The appliance will be easier for a woman than for a man. The adaptive faculties are more developed. In men there is less natural capacity to support a foreign body, on the other hand, more powerful chewing habits subject the upper support surface to excessive pressure.
- AGE:
The older the patient, and the longer he has been toothless, the less he will feel the need for this restoration and the greater the adaptation difficulties will be.
- BEHAVIOR:
Patient behavior should also influence our treatment plan
Look for the reasons that led to the late arrival of the patient.
- If the gag reflex was the major reason for his prolonged toothlessness, local or general drug treatment should be undertaken.
- If allergy is the reason given by our patient, tests will be carried out.
B: LOCAL DIAGNOSTIC ELEMENTS :
WHAT ARE THE ANATOMICAL AND PHYSIOLOGICAL ELEMENTS WHICH SHOULD LEAD US TO THE ESTABLISHMENT OF A TREATMENT DIAGNOSIS:
- PROSTHETIC VALUE OF THE SUPPORT SURFACE:
The bearing surface will be subjected to pressures greater than those that would be exerted on it if the lower arch were artificial. The direction of the forces is also different. The forces will be projected in as many directions as there are natural teeth. Faced with such a threat to its integrity, the bearing surface may present itself in different aspects and impose a different impression technique on us.
- TONICITY OF PERIPHERAL ORGANS:
The disappearance of the alveolo-dental rampart promotes significant cellular infiltration which fills the useful passive space reserved for the prosthesis.
The tongue spreads and covers the lower arch. The swallowing mechanism is disturbed. The Vertical Dimension is reduced, the DONDERS space has disappeared. Tissue and joint conditioning is required before any device. This will be done using a temporary prosthesis.
- OCCLUSAL SCHEME OF THE LOWER NATURAL ARCH:
In complete unimaxillary prosthesis, frequent occlusal disturbances linked to the dentate arch require an analysis of the orientation of the Prosthetic Occlusal Plane.
This analysis of the occlusal plane very often reveals a disturbance which it
must be corrected.
The objective of this correction is to obtain a harmonious distribution of occlusal loads as well as prosthetic stability in Centric Relation and during diduction movements.
Different techniques / such as the MANUAL SPHERICAL CAP, are at our disposal to evaluate the disturbances of the Occlusal Plane
SPHERICAL CAP TECHNIQUE.
Manual Spherical Cap determines an OCCLUSAL CURVE
“IDEAL”
First, make a cast of the dentate arch. It should be placed, first at the posterior anatomical landmark (1/2 of the retromolar trigone), and its convex face folded down onto the occlusal surfaces of the mandibular teeth. It will provide information on the positional anomalies of the cusps of the lower teeth. It allows us to detect and eliminate cusps in poor position.
(The occlusal surface of the posterior teeth should be tangent to the spherical cap).
In the case of a disturbance of the Occlusion Plane, this method allows to evaluate the existing under-occlusions or over-occlusions.
Manual Spherical Cap determines an OCCLUSAL CURVE
“IDEAL”
- A coronoplasty is necessary in the majority of cases. We will talk about
“Remodeling” and “polishing”. The final goal will be to reestablish generalized contact between all the cusps and the spherical cap.
- In the case of excessive extrusion of teeth without antagonists, pulp removal and the creation of cast caps will be used.
If the inter-arch space at their level is too small, plan to remove the second molars on the prosthesis.
4) CHOICE OF ANTERIOR AND POSTERIOR TEETH:
A. CHOICE OF ANTERIOR TEETH :
It may cause controversy with the patient. They should be the same shade as the lower teeth.
Their assembly must always respect the patient’s intermaxillary relationship.
The requirements are as follows:
- Never try to normalize the inter-arch relationship. If there is a lower prognathism, the anterior teeth must be raised to their original position, otherwise a permanent imbalance will be created and the anterior edge will collapse.
- If everything indicates lower retrognathia, one should not try to lingualize the anterior teeth, otherwise the phenomena “Fe and Ve”, “Te and De” and the sibilants “Se and Che” could be disturbed.
In complete unimaxillary P, occlusal control must be frequent because the possible egression of the remaining teeth and especially of the lower incisor-canine group can generate occlusal instability and significant bone resorption linked to the anterior overload.
The maxillary anterior crest risks transforming into a “floating crest” which is very unfavorable for comfort and prosthetic stability.
In this case, the anterior contacts that appeared in centric relation after this egression must be removed in order to always maintain a gap between the anterior natural teeth and the complete unimaxillary P.
TOTAL UNIMAXILLARY ADJOINING PROSTHESIS
B. CHOICE OF POSTERIOR TEETH:
The selection and assembly of posterior teeth also presents problems. Chewing habits result in more or less pronounced abrasion of the cusps of natural molars.
The occlusal anatomy of natural teeth will inform us about the type of chewing and guide the choice of the morphology of the prosthetic teeth which will be rather flat or cuspidate depending on the level and type of abrasion.
To maintain functional occlusion and maintain the integrity of the occlusal structures of the prosthetic teeth and the remaining teeth, it is recommended to oppose materials that are equivalent in hardness and wear resistance.
Ceramic teeth can be placed against natural teeth without much risk of damage.
The very high wear resistance of ceramic encourages the practitioner to choose this material.
In P Complete Uni maxillary, the vestibulolingual diameter of the prosthetic teeth must also take into account the width of the occlusal table of the remaining antagonist teeth.
In P Complete Bi maxillary the discrepancy between the centripetal resorption of the maxilla and the centrifugal resorption of the mandible results in an inclination of the inter-ridge axis in the frontal plane which compromises compliance with the usual rules of functional assembly recommending placing the teeth on the top of the ridge especially in the mandible.
The search for a compromise between aesthetics and function is possible thanks to a mounting outside the crests essentially in the maxilla, sometimes tolerated and which makes it possible to compensate for bone resorption.
In P Complete Uni maxillary upper, the significant inclination of the intercrest axis (Fig.12a, b) resulting from the difference in dimension between the two arches (fig.13), sometimes requires a crossed assembly with risk of lingual and jugal bite.
| Indeed, occlusal stability would be jeopardized by a conventional assembly because the maxillary teeth would project completely outside the crests. For a “totally balanced” occlusion, we will resort to the creation of a compensation curve in the sagittal and frontal plane to recover balancing posterior contacts during propulsion and lateral movements. The creation of such curves at the level of the dentate arch poses difficulties because it requires occlusal corrections often refused by the patient. |
- UPPER TOTAL EDENTATION VERSUS LOWER PARTIAL EDENTATION
- RELATIONSHIPS OBSERVED BETWEEN THE TOTALLY EDENTULOUS UPPER ARCH AND THE POSTERIOR EDENTULOUS LOWER ARCH.
Before any treatment plan, two prerequisites are essential:
- Accurately determine the intermaxillary relationship through correct assessment of the Vertical Dimension and Centric Relation.
- Transfer this relationship to an articulator.
The examination will be conducted in the three planes of space
- In the frontal plane.
- In the anterior region, assess the distance separating the free edge of the lower incisors from the upper alveolar rim: it must be at least 4 mm.
- In the posterior region: Assess the inclination of the inter-alveolar axes and the location of the tuberosities. It is ideal when each tuberosity is equidistant from the occlusal plane and at least 3 nm from the latter.
When the distances are unequal, the assembly is poorly balanced and the occlusal load poorly distributed. Pre-prosthetic surgery is recommended.
Any contact between the tuberosities and the Occlusal Plane must result either in an elevation of the Vertical Dimension, when this is tolerated, or in the removal of the 2nd artificial molars.
TOTAL UNIMAXILLARY ADJOINING PROSTHESIS
- In the sagittal plane
- In the anterior region, one of three inter-arch aspects can be highlighted.
- An upper pro-alveolus opposed to a lower retrognathia.
- An upper retro-alveolus opposed to a lower prognathia.
- A normal relationship between the two jaws.
- In the posterior region, observe the relationship of the tuberosities and retromolar papillae and the orientation of the upper and lower edentulous segments. A space of 3 nm between the tuberosities and the retromolar papillae is necessary. If this space is insufficient, again the Vertical Dimension will be increased within the tolerance limits or a careful remodeling of the tuberosities will be considered.
- In the horizontal plane.
Considering the centripetal resorption of the maxilla and the centrifugal resorption of the mandible, three relationships can arise.
- An upper edentulous arch that has barely resorbed, projecting horizontally outside the lower arch in its portion located between the 1st lower right molar and its left counterpart. This is the most favorable case, the diagnosis is: positive
- An upper edentulous arch in the middle stage of resorption projecting into the lower arch very close to the ridge line.
- An upper edentulous arch in the advanced stage of resorption projecting into the lower arch. The prognosis is always reserved and requires special treatment.
2) HOW TO SOLVE THESE CASES BY THE MOST APPROPRIATE TREATMENT
- Pre-prosthetic treatment
In general the patient presents with a reduced Vertical Dimension characterized
by mandibular protraction and lowering of the commissures. Muscular and joint conditioning will be carried out with the help of a temporary prosthesis.
Pre-prosthetic treatment can be surgical. It will concern the
Ridge regularization, correction of mandibular tori or any
Painful exostoses, or that of the upper alveolar rim in its anterior region.
Remodeling of the tuberosities will occur if they are of unequal volume, when they interfere with the Occlusal Plane or with the retromolar papillae.
- Prosthetic treatment:
- The secondary impression of the upper jaw will be analytical and under digital pressure .
- The lower preliminary impression is not sufficient, an anatomical-functional analytical impression will be adopted after regularization of the free edge of the remaining natural teeth.
- The orientation of the Occlusal Plane will be approached in a classical manner.
- The recording of the Centered Relation may be disturbed by the propulsion reflex due to the persistence of the lower incisor-canine block. It is necessary to eliminate any anterior contact by a sufficient height of the ridges, at the level of the edentulous segments, in order to solicit the most posterior and most physiological occlusion reflex.
In the lower jaw: Rigid prosthesis with indirect support: It contributes to the stability of the upper prosthesis.
If there is a dense fibro-mucosa covering the edentulous segment capable of supporting the efforts of mastication,
If the remaining teeth are firmly embedded in dense bone and healthy periodontium,
When the posterior alveolar rim is large and poorly resorbed,
When the retromolar tubercles can play their positive role in stabilizing the stool,
The plaque will be traced in accordance with the positive and negative biological indices highlighted during the clinical examination.
An immobilization arch will consist of a cingulate bar 1.6 mm wide and 1 mm thick. A stabilization arch or lingual bar will have a width of 4.6 mm and a thickness of 2 mm.
The saddles will be as wide as possible and the retromolar tubercles are covered by the base of the prosthesis.
TOTAL UNIMAXILLARY ADJOINING PROSTHESIS
CONCLUSION
The construction of a complete upper denture in relation to a posteriorly edentulous lower arch involves more problems than any
prosthetic restoration
It requires us to make a precise diagnosis, a pre-prosthetic treatment including
tissue conditioning in all its forms.
The occlusal adjustment of the remaining teeth, the judicious choice of teeth (shape, occlusal anatomy), that of the occlusal scheme and the subsequent checks, favorably condition the success of the prosthetic treatment of a patient totally edentulous in the maxilla who has kept his natural teeth in the mandible.
Prosthetic stability and comfort, ensured by the reestablishment of a correct occlusal plane, promotes the functional integration of the prosthesis.
Optimal occlusal reconstruction contributes to the preservation of tissue integrity by limiting the risks of excessive trauma to the residual maxillary crest.
A complete upper single maxillary prosthesis opposed to a natural dentate arch involves significant forces exerted on the edentulous ridge. This pressure can be exaggerated in the event of incorrect occlusal rehabilitation, causing a lot of pain.
The occlusal difficulties of upper unimaxillary complete removable prosthetic restorations opposed to a fully dentate arch are linked to frequent disturbances of the occlusal plane which must be imperatively corrected in order to ensure prosthetic stability as well as to the situation and anatomy of the antagonistic natural occlusal surfaces which condition the choice of prosthetic teeth and that of the occlusal scheme.
Figure
TOTAL UNIMAXILLARY ADJOINING PROSTHESIS
| Figure The retromolar tubercles are covered by the base of the prosthesis; the hooks are pressure breakers. | Figure: The saddles are as wide as possible, a disjunction d is provided due to the differences in resilience existing between the edentulous segments and the periodontium of the remaining teeth |
Figure
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TOTAL UNIMAXILLARY ADJOINING PROSTHESIS
Wisdom teeth can cause infections if not removed.
Dental crowns restore the function and appearance of damaged teeth.
Swollen gums are often a sign of periodontal disease.
Orthodontic treatments can be performed at any age.
Composite fillings are discreet and durable.
Composite fillings are discreet and durable.
Interdental brushes effectively clean tight spaces.
Visiting the dentist every six months prevents dental problems.