Cervical limits
1. Introduction
A fixed prosthetic restoration must ensure the maintenance of dento-periodontal health, as well as the durability of the prosthetic element.
How can we create the best conditions of intimacy between dental tissue/material surfaces in order to achieve therapeutic success?
2. Anatomical reminder of the biological space
The preparation limit of a reconstruction must never take the risk of desecrating the integrity of the biological space.
3. Definition of the cervical limit
- Defined as the place where the preparation of the contour shapes of the anchoring means of the prostheses must stop.
- It represents the end in the occluso-apical direction of the preparation.
4. Roles of the cervical limit
- Ensures continuity at the cervical level, of the prosthesis with the tooth without overflow.
- Ensures a watertight seal by preventing the dissolution of the sealing cement.
- Provides strength to the prosthesis due to the thickness of the metal. (support chewing forces).
- Allows readability of the peripheral contour of the preparation both in the clinic and in the lab.
5. Location of the cervical limit
The first condition for correctly locating the cervical limit is the presence of a healthy gingival sulcus. (Rehabilitation)
In the axial plane, the relationships between the marginal edges of the preparations and the free marginal gingiva can be of 3 orders:
- supragingival limit
- juxta-gingival limit.
- subgingival limit
Selection criteria
The choice of the location of the cervical limit of the preparations is directly dependent on the clinical conditions:
- Anatomical considerations: short clinical crowns.
- aesthetic considerations
- notion of biological space
- height and thickness of attached gingiva
- patient’s ability to eliminate plaque.
a) Supra or supragingival cervical margin:
It has no contact with the marginal periodontium, is located above the gingival margin, at a distance of 1 to 2 mm.
- Indications
– Posterior teeth
– Sufficient crown height
– Excellent oral hygiene
- Benefits
– Easy execution
– Without gum irritation
-Good visibility
-Ease of adjustment and finishing
-Economy of dental tissue
- Contraindications
– Anterior teeth
– Insufficient crown height
– Lack of hygiene.
- Disadvantages
– Risk of caries
– Unsightly
- Juxta-gingival cervical margin
Located at the same level as the marginal edge of the gingiva.
- Indications
– good hygiene
– stabilized periodontium
- Benefits
-protection of supragingival enamel
-no lesion of the sulcular epithelium.
-accessible to brushing.
- Contraindications
– poor hygiene
– unstabilized periodontium
- Disadvantages
– Rapid transition to supragingival situation due to passive eruption.
c) Subgingival or intrasulcular limit
The finishing line is located in the gingival sulcus.
The cervical edge of the preparation is not in direct contact with the oral environment
This limit should not exceed half the depth of the furrow, and should respect the biological space.
- Indications
- Anterior and posterior teeth
- Short teeth
- Healthy and stabilized periodontium.
- Benefits
– preserves aesthetics
-increases retention.
-prevents carious lesions
- Disadvantages
-Delicate realization
-Risk of damage to the attachment
-Difficulty in finishing and polishing the joint. (source of marginal irritation)
- Contraindications
– Thin marginal gingiva
– Bonded prosthesis due to gingival fluid.
– Severe valvulopathy.
6. Different shapes of cervical boundaries
There are several types of finishing line
Selection criteria
- Best quality of JDP
- Good foundation for infrastructure
- To be able to accommodate the metal infrastructure and the cosmetic material
- a good recording when imprinting
- better flowability of the metal
a) long bevel : made with a conical cutter.
Advantages: • Preparation is less mutilating
• Ease of execution
Disadvantages:
• Thinness of the underlying metal.
- does not allow the use of cosmetic material.
- unreadable on model.
The Indication – Richmond
– metal crown
b) shoulder : angular molding, made with a flat-ended cutter .
Disadvantages
– significant tissue mutilation
– unsatisfactory metal flowability
– not a good flow of cement
– quality of JDP is reduced
Benefits
– Legible
– Resistance of prosthetic edges
Indicated: – ceramic jacket
– CIV vest
– CCM
Variants:
Chamfered shoulder: the edge is no longer perpendicular to the axial wall but obtuse, the prosthetic edge is therefore acute.
- Good dento-prosthetic joint.
- Allows the cement to flow.
Rounded angle shoulder: where castability is improved
Chamfered rounded angle shoulder
c) fillet : 1/4 circle concave molding made with a round-ended cutter.
Advantages: – Little mutilating limit.
– better distribution of constraints
– Legible
– infrastructure resistance
– better flow of cement
– better flowability of the metal
Indicated: – metal crown
– Oral CIV
Conclusion
A sealed prosthesis can only remain in the oral cavity if its adaptation to the finishing lines of the preparation is precise.
It is therefore important to respect the sealing of the dento-prosthetic joint and the health of the periodontal environment.
Cervical limits
Cervical limits
Cervical limits
Cervical limits
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.