Cervical limits and emergence profile
Cervical boundaries and emergence profile
Summary :
1-Introduction………………………………………………..1
2-Definition: cervical limit…………………………..1
3-Anatomical reminders:
*The gingivo-dental sulcus………………………………2
*Biological space………………………………………….2
*cervical limit …………………………………………….2
*Root emergence profile…………………………2
4-The marginal gingiva-cervical limit relationships
4-1- Supra or supragingival margin………………….2
4-2- Juxta gingival margin……………………………..3
4-3- Intrasulcular limit…………………………….3
5- Clinical forms of the cervical limit
5 -1-Cervical limit in the form of finishing areas …4
5-2- Linear cervical limit …………………………4
6-Instrumentation ………………………………………..4
7- Conclusion………………………………………………..5
8- Bibliographic references…………………………..6
1-Introduction: [1]
The cervical limit is probably the most sensitive area of a prophetically restored tooth. It is at this location that the practitioner will sign the success or failure of the prosthetic restoration from both an aesthetic and periodontal point of view.
The cervical limit of a tooth is decisive for the success of fixed prosthesis. It is the place of biological, physiological and aesthetic integration of a prophetically restored tooth. It is also what characterizes the quality of the dento-prosthetic joint, which in turn determines the adjustment and durability of the restoration. And there is no universal type of cervical limit.
2-Definition of the cervical limit: [2]
It represents the end in the occluso-apical direction of the preparation, defined as the place where the preparation must stop, considered as the place of meeting and cohabitation of the dental tissue, the gingival tissue, the epithelial attachment and the prosthetic material, bathed by the gingival fluid and regularly colonized by dental plaque (Fig 1).
Cervical limits and emergence profile
Fig 1 : Cervical limit of a crown and its emergence profile (in blue)
3-Anatomical reminders: [2]
3-1 Gingivodental groove:
The gingivodental groove or sulcus is a V-shaped space between the free gum and the tooth, its depth is between 0.5 and 2 mm.
The sulcus includes:
-A gingival wall
-A dental wall
-A background: junctional epithelium or epithelial attachment constituting a border between the internal environment and the external environment
The sulcus contains the gingival fluid (Fig 2).
Cervical limits and emergence profile
Fig 2: The gingivo-dental sulcus and the biological space
3-2 Biological space: [2,3,4]
It is the space between the bottom of the sulcus and the top of the alveolar bone crest, its average value is 2.04mm
It includes:
An epithelial attachment + a connective tissue attachment
It constitutes the red zone that must be respected without ever crossing it.
The emergence profile: [4,5,6,7]
Croll defines it as “the part of the axial contour of a tooth extending from the base of the gingival sulcus through the free gingiva toward the oral environment.” An emergence in line with the root surface is more favorable to periodontal health. Most teeth have an emergence profile at the cementum-enamel junction that is in line with the root zone (Fig 3).
Cervical limits and emergence profile
Given by Stein. This angle β is the intersection between the
Emergence profile (line b) with the major longitudinal axis of the tooth (line a).
Fig 3: Concept of emergence angle
If the emergence profile is too flat, there is a risk of under-contour and absence of curvature → aesthetic problem. There will also be large embrasures (= part which is under the point of contact), there is then a great risk of food jamming.
If the emergence profile is too large, there is an overhang → hygiene problem (plaque formation and inflammation).
4-Marginal gingiva-cervical limit reports: [1,2,8]
Clinically, the situation of a finishing line is expressed in relation to the marginal gingiva
- 4-1: Supragingival margin:
It is located 1 to 2 mm above the gingival margin.
- Benefits :
- No risk of gum damage
- Good visibility
- Easy to adjust and finish
- Saving dental tissue
- Easy control of the dento-prosthetic junction
- Disadvantages:
Unsightly
- Indications:
- Posterior tooth
- Sufficient crown height
- Minimal attached gingiva
- Excellent hygiene control quality
4-2-Juxta-gingival limit:
Same level as the gingival margin
- Benefits :
- Without risk of damage to the attachment
- Accessibility to brushing
- Disadvantages:
- Quickly moves to the supragingival situation
- Indications:
- Good hygiene
- In the presence of stabilized periodontium
- In young patients
4-3-Intra-sulcular limit:
- Benefits :
- Aesthetic
- Disadvantages:
- Delicate realization
- Risk of damage to the attachment
- Difficulty in polishing the bonding joint
- Indications:
- Anterior tooth
- Dyschromia of the pulpless pillars
- Healthy, stabilized periodontium
- Root sensitivity
- Loss of tooth substance
5-Clinical forms of cervical limit: [1,2,8]
5-1 Cervical limit in the form of finishing areas:
A boundary in the form of a finishing area is not clearly demarcated from the intact part of the tooth. Although simple clearance (Fig. 4-1) and trace finishing (or knife edge—Fig. 4-2) are valid cervical finishes, they are less used in practice.
Easy to make, very economical, however not recommended because they do not allow sufficient thickness for the prosthesis. The majority of authors agree that today this form of finishing is no longer justified : an apparent tissue economy is paid for by a real imprecision of the limits in the laboratory and by a possible over-dimensioning of the prosthesis which induces unacceptable chronic periodontal aggression.
- Used as a cervical limit when making inlays, onlays, inlay cores.
Cervical limits and emergence profile
Fig4-1: Stripping Fig 4-2: Trace
5-2- Linear cervical limits:
5-2-a- The Fillet: fillet or ¼ round or ¼ oval
- Allows for better distribution of stresses, Readable, resistance of the infrastructure; Better flow of the sealing cement, Better flowability of the metal
- Used as the best cervical limit for a cast crown, resin CIV
5-2-b- The shoulder: is a wide flat area forming a clear boundary, provides enough space for the prosthetic material, however very mutilating; Better flow of the sealing cement
- Used as cervical limit for ceramic-ceramic crown; ceramic vestibular inlay crown, metal-ceramic crown
The shoulder has three variations:
Obtuse angle shoulder: 135º
Right angle shoulder: 90º
Rounded internal angle shoulder
Cervical limits and emergence profile
Fig 5: Shoulder variations
a- Obtuse angle shoulder: 135º b- Right angle shoulder: 90º c- Rounded internal angle shoulder
NB: The straight shoulder with a rounded internal angle can be approached in two ways: either a straight shoulder is first produced (with a flat-ended conical cutter) whose internal angle is then rounded (with a conical cutter with rounded angles), or the shoulder is produced in a single operation with the cylindrical cutter with rounded angles.
Fig 6: The different forms of cervical limit
6-Instrumentation: [1,2]
The practitioner must ensure a match between the shape and diameter of the bur according to its grain size, i.e. the size of its diamond chips (coarse grain, medium grain, or fine grain bur).
Cervical limits and emergence profile
The choice of the shape of the cervical boundary depends on: [1,2,8]
1 – From the clinical situation
2-The type of prosthetic restoration
3- The aesthetic requirement
Conclusion :
In fixed prosthesis, impression techniques require access to the limits which call for either deflection or gingival eviction.
In this regard, access to the infrasulcular cervical limits is the clinical factor determining the restoration of a natural-looking dento-gingival aesthetic.
Bibliographic references:
1- Shillingburg. The fundamental bases in fixed prosthesis. Editions CDP 1982.
2- J Schittly. Impressions in fixed prosthesis. Editions CDP 1998
3- Malidin Clémentine. Thesis University of Nantes: Techniques for accessing cervical limits in fixed prosthesis : Indications and Impacts on periodontal health. Year 2016
4-2013S. Armand, H. Couret: Emergence profile in fixed prosthesis: Interests of the double impression. Prosthesis notebooks no. 125 March year 2004.
5-S. Armand: Access to cervical limits in fixed prosthesis: Indications. ADF notebooks – No. 7 – 2000.
6-Aude Vallata. Thesis University of Nancy. Cervical limit in fixed prosthesis: Concepts and Precepts. No. 3652 year 2011.
7-Louise Voillaume.These University of Lorraine. The emergence profile on natural teeth in fixed prosthesis: Concept and precepts. No. 9437 2017
8-Philippe Viargue. The position of the cervical limits of preparation in fixed prosthesis: Analysis of the literature. Revue d’ondonto stomatologie 2005;34:3-18
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