Layering techniques

Layering techniques

Layering techniques:

Introduction :

Direct anterior restorations in composite resin using the stratification technique have seen significant development over the last 10 years due to significant progress in the mechanical and, above all, optical properties of resins, in order to meet the aesthetic requirements of the patient while also meeting functional and biological imperatives.

1. Definition of Stratification:

Stratification: nf (layering incremental placement(of restorative material):

Technique of placing a composite by adding successive increments, allowing the use of different colors and consistencies, to improve quality

functional and final aesthetics of the restoration ( French dictionary of Conservative Odontology terms)

2. Objectives of stratification techniques:

• the reproduction of nature
• favor the circulation of light
• an operating methodology that allows for predictable and reproducible results.

3. Indications and contraindications:
   1. INDICATIONS:

• Coronal fracture following trauma
• Resumption of a restoration that had become unsightly
• Carious lesion
• Defect in shape or color.

2. CONTRAINDICATIONS:

• Large-scale lesion
• Significant dyschromia
• Difficulty reproducing the shade (significant dyschromia)
• Difficulty in reproducing the shape and hermeticity of restorations

4. Evolution of stratification concepts:
   1. Historical two-layer technique:

A first layer is made with a composite having the overall aesthetic properties of the tooth, then an incisal or transparent composite is then added to mimic the incisal edge.

The aesthetic success of this type of restoration is based on the mimicry properties of the composite used in a single shade.

2. Historical three-layer technique

It is a three-layer technique using:

• opaque dentin,
• a body dentin
• an enamel composite.
  • The biggest difficulty is to measure the thicknesses of the different materials.
  • If this technique is poorly mastered, less satisfactory results are obtained from an aesthetic point of view than with two-layer techniques with a “mimetic” composite.

Opaque wall → enamel-dentin body → incisal:

3. The “modern” concept in 2 layers:

Two base masses, enamel and dentin, will be applied reproducing the arrangement of the natural tissues of the tooth.

• The materials used must have the same optical characteristics as the tooth
• The dentin masses of decreasing saturation will be applied successively, while the enamel masses will be applied according to the spatial configuration of the natural tooth

4. The “modern” concept in 3 layers:

This layering method is the most advanced. It will be based on the same enamel and dentin bases as the modern two-layer concept, and will include additional effect materials.

These latter, interposed between the dentin and enamel layers, will make it possible to recreate the tiny variations in the internal anatomy of the natural tooth.

Palatal enamel → Dentin → (Effect masses) → Vestibular enamel

Here the limits are prepared in the form of a rounded chamfer in order to provide sufficient thickness for the dentin which will be covered by a thin layer of enamel in order to obtain optical continuity between the restoration and the natural tooth.

5. Stratification method:
   1. Development of the tooth color map:

• The tooth will need to be cleaned first with polishing paste to remove the exogenous film. The contralateral tooth will be observed to establish an accurate map.
• The observation is structured around three areas:

-The cervical region

• The middle region (body of the tooth)
• The incisal third

1. the cervical region : This is the area where the color of the dentin is determined because the enamel is thin and has little influence on the perception of the shade.
2. Middle region (body of the tooth): We will determine the degree of saturation of the dentin as a whole. The selection of the enamel mass is done

also in this area because the thickness is maximum there

3. the incisal third: Here we will have to observe the internal dentin architecture, the more or less translucent areas, the chromatically saturated areas (in the case of hypoplasia), the presence of opalescence effects and the anatomy of the free edge. This is the most complex area, where it will be possible to animate the restoration.
4. Tooth analysis
   1. Choice of shade:

• The shade is taken on a clean mouth, before preparation and placement of the dam and on hydrated teeth.
• Lighting: turn off the surgical light and any stray lighting (neon lights).
• Place the patient in front of a dimly lit window with natural light
• Remove interfering colors (red scarf, lipstick, bright makeup)
• Work with the naked eye for colors and with a magnifying glass for surface condition details
• We take the shade guide knowing that the schematized color is significantly different from that of the composite once photopolymerized

2. Shape and geography:

The macrogeography (anatomy of the tooth in the vertical direction) is made up of the lobes, grooves and pits present on the surface, residues of the embryonic fusion of the lobes

Microgeography (anatomy in the horizontal direction) is represented by the surface texture of the tooth , remnants of growth striations

3. Operating protocol for stratification on anterior teeth:
   1. Preliminary clinical steps:

• initial periodontal therapy
• static and dynamic occlusion control
• establishment of a watertight operating field
• vestibular and proximal chamfer

2. Stratification itself;
   1. Development of the palatal face using the silicone guide:

A thin layer of selected enamel composite is placed at the guide level to obtain a translucent and functional palatal surface. In low thickness

2. Production of the proximal face

This is a delicate step because it will fix the framework of the restoration and its future contours. with the same composite used to recreate the palatal wall

3. Dentin stratification itself:

The assembly of the dentin masses is done by varying the saturations and respecting the internal architecture (arrangement of the dentin lobes, shape, number).

Restoration of the dentin lobes with less saturated dentin masses and placement of bluish opalescent masses between these lobes.

4. Placement of the enamel mass for the reconstruction of the enamel wall .
5. Finishes:

The finishing stage involves recreating the morphology and surface condition of the reconstruction. A thorough polishing process will then be necessary for optimal aesthetic and functional integration.

Firstly, the general anatomy of the tooth is controlled by the use of discs with increasingly finer grains.

In a second, macromorphology is carried out: the use of diamond cutters of decreasing grain size at low speed allows the vertical anatomy to be recreated on the surface of the composite (concavities, convexities, grooves, transition lines, flats, etc.).

In a third step, the micromorphology of the restoration is carried out . This is the surface texture of the composite. With a diamond burr of grain size corresponding to the relief to be recreated, and by a horizontal movement at slow speed

4. Polishing.

Finally comes the polishing phase. We can proceed in two main ways: on the one hand using polishing discs of decreasing grain size, and on the other hand using silicone cups and grinding wheels.

6. Conclusion :

The design of aesthetic restorations is constantly evolving thanks to increasingly efficient materials in terms of aesthetic rendering, light circulation and

surface condition.

The practitioner must consider smile restoration as part of a multidisciplinary approach depending on the different clinical situations and patient complaints.

The principles of colorimetry and stratification allow the practitioner to reproduce a natural appearance of the tooth .

Layering techniques

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Layering techniques