Bridge Intermediates
1) INTRODUCTION
The span of the bridge that spans the edentulous space and replaces the missing teeth in a functional and aesthetic way, represents the reason for the joint prosthesis. Its design must obey clinical indications based on a careful clinical examination that is the only guarantee of the success or failure of our prosthetic therapy.
The biological integration of the bridge intermediary is essentially linked on the one hand to its morphology, to the nature of the material used and to the constraints exerted on the missing teeth by means of the connections and the anchoring means . Once assured during the production of the prosthesis, the prosthetic manufacture must be able to respect:
- The morphology of the contact surface
- Good occlusal morphology
- Good axial morphology
- All this is associated with the use of material which does not present any aggression at the tissue level, and on the other hand a good surface condition of its materials.
2) DEFINITION
The bridge span is the element that spans the edentulous space and replaces the missing natural teeth ; it is connected by rigid connections or welds to the anchors themselves fixed to the preparations of the natural abutment teeth.
Depending on its length relative to the extent of the tooth loss, there are two types of bridges: short-span or long-span bridges.
Different names with the same meaning are mentioned in the literature such as:
Beam, span, intermediate, pontic
3) OBJECTIVES OF THE SPAN
- Restore function
- Restore aesthetics
- Ensure hygiene
- Maintaining the balance of the masticatory system
- Not be the cause of the degradation of the tissues with which it is related and be biologically acceptable.
4) external morphology of the span
The shape of the spans must be analyzed according to its various faces according to the morphological and physiological factors of the different tissues and organs with which the span maintains relationships, according to hygiene factors, mechanical factors and finally aesthetic factors.
41) Relationship with antagonist teeth
The reestablishment of occlusal relationships with the antagonists allows both to restore masticatory efficiency and to maintain the stability of the occlusion by registering the occlusal face of the trabecula in the patient’s occlusal schema.
This morphology of the surfaces must be conditioned on the one hand by the functional movements of the mandible and on the other hand by the morphology of the antagonist teeth.
The main objective is to direct and distribute the forces on the deep periodontal tissues of the abutment teeth.
The cuspid angulation must be performed or analyzed, which is related to the patient’s age, occlusal pattern and the anterior guide.
This angulation must correspond to that of the antagonist teeth but it is the anterior guide which truly conditions the height, the orientation of the cusps on a semi-adaptable articulator.
The width of the occlusal tables should be analyzed in general, it is recommended to reduce the vestibulo-lingual diameter of the occlusal tables to limit the importance of the forces applied during chewing which will relieve the periodontal support of the abutment teeth, however the reduction in the width of the tables must not lead to too great a reduction in the overjet otherwise there will be a cheek bite or creation of an area suitable for the accumulation of plaque.
42) Relationship with adjacent teeth
To avoid any deformation or fracture, it will be necessary
- Increase the thickness of the anchor opposite the span.
- Establish a wide anchor span contact: at the level of the proximal contacts, the mechanical requirements of the anchor span connection require that a sufficient section of the frame be provided; the proximal faces must delimit wide and easily accessible embrasures necessary to allow hygiene maneuvers by the patient.
- Ensure that the span is of sufficient cross-section to avoid any deformation or fracture.
43) Axial morphology of the span
The vestibular and lingual faces must have a convex profile, the proximal faces must delimit wide and easily accessible embrasures. The contact surface with the element adjacent to the anchors must not exceed the 1/3 occlusal and 1/3 middle zone to allow access for cleaning.
44) Relations with the edentulous crest
The bridge intermediary must not create direct mechanical action, contact with the crest must be reduced and without pressure.
It must not create direct or indirect mechanical aggression through plaque retention, this retention must be minimized by a polished surface and on the other hand the morphology must allow cleaning by maximum clear embrasures.
Depending on the nature of the relationship between the bridge span and the edentulous crest, the extent of the edentulation and the nature of the material used, different types of span are distinguished:
According to the reports with the edentulous crest:
441) The supra mucosal trabecula : also called the hygienic trabecula
This is a type where the span passes in a bridge clearly at a distance from the mucosa of the edentulous crest, it is convex in the vestibulo-lingual and mesio-distal direction. The face located opposite the crest is convex to facilitate cleaning.
Indication:
– Reserved for the lateral mandibular sectors not visible for aesthetic reasons
– Sufficient space available: ridge too resorbed
Benefits :
- very hygienic
- very solid because it is entirely metallic
- non-irritating
Disadvantages:
-unsightly
-requires a certain occlusion height given the 03mm space between the crest and the span.
Bridge Intermediates
442) contra or juxta mucosal trabeculae :
Two main forms:
4421) Ovoid type:
Egg or shell shaped, convex intrados, small area of contact with the top of the ridge, large clearance of the embrasures, easy to clean, well tolerated.
Disadvantages:
- Vestibular face in its cervical part is not always aligned with the adjacent teeth, are not very aesthetic
- Used for less visible mandibular teeth.
4422) Classic saddle type:
The span having a shape very close to that of the tooth, it covers the crest with a large concave contact surface. Hygiene maneuvers are not easy, it is a source of inflammation
4423) Stein modified saddle type:
This author proposes to modify the classic saddle and to keep only the vestibular part which is aesthetic, the lingual covering up to the top of the crest inclusive is eliminated, only a vestibular contact surface close to the top of the crest of small extent remains, the entire gingival surface is convex. It has the advantage of being aesthetic and hygienic
- Intra or infra mucosal trabeculae :
It penetrates the crest in the form of an alveolar outline
To be avoided, large contact surface with the crest, difficulty in cleaning -> causes inflammation, the results are satisfactory at the beginning but random thereafter, sometimes catastrophic due to lack of hygiene
45) Depending on the extent of the tooth loss : we distinguish
1) short span : it has excellent resistance, it replaces one or two teeth
2) long span : it is subject to mechanical deformations, it replaces more than three teeth, it will be necessary to reduce the width of the occlusal faces to reduce the masticatory forces while avoiding the relief of the occlusal face being too marked
46) According to the topography of the tooth loss : we distinguish
1) straight span : it is located at the level of the lateral sectors
2) curved span : it is located at the level of the anterior incisor-canine sector, and in addition to the forces exerted on the straight spans, the rotational forces are added to this type of span, the metal undergoes additional twists which will transmit much more harmful forces to the pillars.
5) Materials used
51) Selection criteria :
511) Aesthetic conditions: the span must be entirely metallic but for aesthetic reasons the span must have a cosmetic vestibular facet with an unalterable material
512) Biological conditions: the material must not irritate surrounding biological products.
513) Functional conditions: the material must have sufficient resistance to the masticatory function.
52) The various materials used
521) Cosmetic materials :
It must be unalterable, must not oxidize under the influence of saliva and oral flora
- Resin: The resin intermediate eventually gives off a foul odor due to the degradation of the surface by oral bacteria.
- Porcelain
- Ceramics
522) The metallic material:
- Precious alloys:
- platinum or type 3 gold (hard gold)
- platinum or type 4 gold (very hard gold)
5222) Non-precious alloys:
- nickel chrome
- cobalt chrome
In all cases, it is necessary to avoid placing the junction of the two materials in contact with the mucous membrane.
The intermediary should approximate the shape of natural teeth to promote aesthetics.
Bridge Intermediates
6) Conclusion : In the design of a joint prosthesis, the essential objective regarding the design of the trabecula is to minimize the possibilities of accumulation of bacterial plaque, for this it is necessary to motivate the patient to daily oral hygiene essential for the daily elimination of plaque. Also it is essential to achieve an adequate morphology and surface condition of the trabecula and adapt it to the clinical situation of the edentulous ridge.
Bridge Intermediates
Deep cavities may require root canal treatment.
Interdental brushes effectively clean between teeth.
Misaligned teeth can cause chewing problems.
Untreated dental infections can spread to other parts of the body.
Whitening trays are used for gradual results.
Cracked teeth can be repaired with composite resins.
Proper hydration helps maintain a healthy mouth.