ADHESIVE RESTORATIVE THERAPEUTICS
Introduction :
The aim of restorative dentistry is to restore the dental organ’s form, function and aesthetics while preserving the vitality and health of the pulp as much as possible.
The keys are better knowledge of pulp biology, improved adhesive techniques and the development of biomaterials.
Since the early 1960s, the quality of adhesive techniques and materials has greatly improved, and probably no other restorative system has been the subject of such intense research.
I/ Definition of restoration:
Restoring a tooth means putting it back in good condition, giving it back the appearance of a healthy tooth.
Immediately, we think of a decayed or fractured tooth, and restoring becomes reestablishing the integrity of the tooth; it is reconstituting it, reconstructing it.
Generally speaking, the definition of restoration is as follows:
The restoration of a tooth consists of restoring, using any material, its morphology and physiology; it is to produce what is commonly called a prosthesis.
II/ The objectives of the restoration :
The question must be asked on two different levels, on the surface, in relation to the physiomorphology of the teeth and in depth, in relation to the tissue structure.
This has the following consequences:
-the chewing potential of the tooth is reduced.
-the masticatory physiology linked to the morphology is disturbed; it becomes pathological:
• Loss of a contact point causes food blockages and interdental plaque which will lead to destruction of the papilla and septum, formation of a pocket and the outbreak of caries on the adjacent tooth.
• Alteration of a cervical bulge promotes rupture of the epithelial attachment of the gum.
The aesthetic appearance of the tooth is all the more altered the more anterior and visible the tooth is.
-the loss of substance may have fractured and sharp enamel edges, likely to injure the soft parts.
For all these reasons, it is therefore necessary to fill the loss of substance in the teeth to restore their shape, their color, their role in the masticatory function, but also to separate, like enamel, dentine from the oral environment and the germs it contains and from all external aggressions.
The current objectives of restorations are oriented towards functional but above all aesthetic restorations, hence the advent and evolution of aesthetic dentistry.
ADHESIVE RESTORATIVE THERAPEUTICS ADHESIVE RESTORATIVE THERAPEUTICS
III/ Principles of adhesive restorative therapies:
Modern aesthetic dentistry today takes the form of an architecture based on biological, biomimetic and aesthetic foundations that guarantee the overall integration of the restoration within the patient.
1- Biological principles : represented by:
•Biocompatibility and pulp protection:
The current model of restorative dentistry has the triple objective of:
– master the causes of aggression before intervention,
– save mineralized tissues and limit operative trauma during surgery,
– to maintain the results over time after filling using a biocompatible, biofunctional and waterproof adhesive restoration.
This model is made possible by the constant progress made in adhesive dentistry. The tissue economy that it allows has a double interest:
* firstly on the biomechanical level by the reduction in the size of the cavities (resistance of the residual dental structures, and their reinforcement by bonding), which is essentially accompanied by the reduction in the number of open tubules, and therefore of the communication pathways towards the pulp parenchyma, which presents a certain biological interest (Simon et al., 2008).
ADHESIVE RESTORATIVE THERAPEUTICS
It is also essential to mention the importance of prior assessment of the terrain (initial state of the pulp-dentin organ), in fact, many failures are due to diagnostic errors.
• Systematic hybridization of bonded interfaces:
Total adhesion means adhesion to all surfaces of the preparation, even those very close to the pulp. It is this notion of “total adhesion” that has raised the controversy over the use of protective bases under adhesive restorations (Ritter et al., 2003).
New adhesive systems are able to reliably ensure this sealing via a so-called hybrid layer.
2 Biomimetic principles:
In restorative dentistry, biomimicry begins with understanding the arrangement of hard tissues and relative stress distribution within the intact tooth.
Thanks to the improvement of bonding protocols and the development of restorative materials, the behavior of the enamel-dentin complex can be partially imitated.
In this context, it is reasonable to conclude that new restorative approaches (infrastructures and superstructures) do not aim to create stronger restorations, but rather restorations compatible with the mechanical and biological properties of the underlying dental tissues: this is biomimetics.
3- Aesthetic principles:
Today, patients’ demands are no longer incompatible with the principles of dental practice. It is possible to make things “beautiful” without transgressing functional and biological imperatives.
The tooth (clinical crown and root), the gingiva and the periodontium form an optical unit. Light diffuses into the tissues, and it is important not to disturb this delicate system by the use of inadequate opaque restorations.
The disappearance of metal in infrastructures (ceramic-ceramic restorations and in superstructures (evolution of the stratification technique and ceramic copings) as well as the use of an invisible assembly method (translucent bonding polymer) have made it possible to offer restorations with a natural appearance, thus ensuring a better aesthetic result.
IV/ Adhesive restoration techniques on vital teeth:
IV/ 1- the different techniques for restoring anterior teeth:
Depending on the extent of the loss of substance, the quality of the residual dental structures, the patient’s assets and the means available, two types of restoration can be considered: direct (direct application of the restorative material) and indirect (via the laboratory stage).
Each technique, direct or indirect, must be well known and well practiced in order to best optimize the functional and aesthetic result.
- Direct composite resin restorations: Layering technique
Direct composite restorations are among the most popular of these because they can be performed in one session, are reliable in the medium term thanks to constantly improving enamel-dentin adhesion, and are financially accessible to most people.
a- Indications and contraindications for direct composite resin restorations:
• fillings of class III, IV and V cavities
• trauma, changes in the shape of teeth, masking malformations and localized discolorations.
This contraindicates the generalization of the prescription of composites in patients who have not all benefited from prior oral sanitation.
b- Stratification technique:
Several authors (Vanini 1996, Dietshi 1995, Magne 1996) have sought to standardize a restoration methodology concerning the stratification steps to obtain reproducible and predictable results.
Stratification is carried out in several stages
1-Establish the chromatic map of the tooth : this is the careful observation of three zones:
• Cervical region: This is the area where the color of the dentin is determined.
• Median region (body of the tooth): We will determine the degree of saturation of the dentin as a whole, knowing that the average color is obtained by a superposition of more or less saturated layers.
The selection of enamel masses is done in this region due to its thickness.
• Incisal third: This is the area of greatest animation where we really bring our restoration to life.
2-Analysis of the tooth : shape and geography
This is an essential step because it determines the integration of the restoration into the smile. Particular attention must be paid to the surface condition of the tooth and its organization.
ADHESIVE RESTORATIVE THERAPEUTICS
Macrogeography (vertical anatomy of the tooth) is made up of the lobes, grooves and pits present on the surface, residues of the embryonic fusion of the lobes. Microgeography (horizontal anatomy) is represented by the surface texture of the tooth, remains of the growth striations.
3-Preliminary clinical steps:
Several clinical steps precede the actual technique (initial periodontal therapy, static and dynamic occlusion control, establishment of a watertight operating field) in order to ensure the functional and biological integration of the restoration.
An important preliminary step before stratification is the bonding procedure which forms the foundation of the restoration. (The manufacturer’s recommendations must be followed depending on the adhesive system used).
ADHESIVE RESTORATIVE THERAPEUTICS
4-Stratification:
a/ Development of the palatal face using the silicone guide: A thin layer of selected enamel composite is placed at the level of the guide in order to obtain a translucent and functional palatal face.
b/ Creation of the proximal face:
This proximal crest fixes the transition lines and regulates a large part of the light phenomena.
For this, a transparent polyester matrix is used, placed in a cradle at the level of the palatal surface, which must be associated with plastic interdental wedges in order to obtain a powerful contact surface.
The masses used for this area are enamel masses, or opalescent effect masses in order to recreate the chromatic animation of the tooth generally dominated by the presence of enamel in significant thickness.
c/ Reproduction of the high diffusion layer: The latter aims to recreate this protein-rich layer that is the enamel-dentin junction. It is reproduced using a weakly charged, white resin, in order to ensure light support.
d/ Dentin stratification proper: We start by using dentin masses of high saturation at the level of the most cervical region then progressively, as we move incisally, we use less saturated dentin masses. It is at the level of the last contribution of dentin mass that we begin to prefigure the future relief of the tooth (macrogeography).
e/ Characterization: Special effect masses may be used to personalize the restoration; interposition of bluish opalescent masses between the dentinal lobes or on the proximal edge, application of intensive white shades to reproduce possible hypoplasia, mainly at the level of the incisal third.
f/ Placement of the vestibular generic enamel layer: Some teeth may have a very transparent incisal edge over the last 2 millimeters; the generic enamel then stops before this area, which is reserved for the application of a specific incisal mass (different opalescents).
5- Roughing : its principle is based on:
• development of primary relief: The majority of macrogeography is created during internal stratification to adjust the arrangement and thickness of the dentin and enamel layers.
• Creation of surface texture: microgeography
6-Polishing and buffing of the composite : Direct composite restorations can be integrated as an aesthetic solution in the short and medium term (4 to 7 years), provided that they are carried out in good conditions and associated with regular annual check-ups.
ADHESIVE RESTORATIVE THERAPEUTICS
B-Direct composite vestibular veneers ; Direct composite vestibular veneers have physical and aesthetic limitations.
They are normally used when the enamel undercut is low or when ceramic vestibular veneers are contraindicated.
These veneers are particularly indicated in young children with dyschromia, hyperplasia and severe vestibular erosion. In adults too, they have decisive advantages: only one chairside session is necessary, and there are no laboratory costs.
The therapeutic sequence : it includes:
1- Enamel preparation : partially remove the enamel; leaving enough space to obtain correct contours of the filling.
2- Proximal preparation : a small proximal and cervical cavity will be formed to facilitate the placement and finishing of the composite. The diamond bur must be held parallel to the tooth surface to ensure uniform enamel clearance.
ADHESIVE RESTORATIVE THERAPEUTICS
Application of the etching solution (with phosphoric acid), application of the bonding adhesive and photopolymerization:
Care must be taken to ensure that the teeth are not stuck together by the bonding adhesive. To do this, strips will be placed between the teeth during polymerization.
4- Assembly of the composite stratification : The deepest layer can be made of a slightly more opaque resin; for this purpose, very low viscosity resins are very useful.
5-Modeling the inlay : the installation and rough modelling of the composite can be done using a spatula.
6-Finishing the inlay : after having carried out the direct finishing of the inlay (the excess on the cervical edges will be carefully removed using a scalpel blade), a low viscosity resin will be placed on the surface of the composite
ADHESIVE RESTORATIVE THERAPEUTICS
ADHESIVE RESTORATIVE THERAPEUTICS
C-Direct glass ionomer restorations ; The clinical applications of glass ionomer cements are varied and it is type II.1 cements that are used for aesthetic restorations.
The main reasons for using these restorative materials properly are:
• The ability to achieve aesthetics and translucency with both self-curing products and resin-modified materials
Physical properties are sufficient as long as the restoration is fully supported by the surrounding tooth structure and is not subject to occlusal interference.
• Adhesion with the underlying tooth structure can be achieved by an ion exchange mechanism, thus completely eliminating the risks of micro-infiltration.
• The material acts as a fluorine reservoir.
Implementation technique:
1- Cavity conditioning: Application of 20% polyacrylic acid with a microbrush for
10 seconds (20 seconds if the concentration is 10%).
Then rinse thoroughly for 10 seconds and dry briefly without dehydrating the surface.
ADHESIVE RESTORATIVE THERAPEUTICS
2- Preparation of glass ionomer cement:
For non-pre-dosed products:
Preferably use a non-absorbent spatula and a plastic spatula.
Shake the powder bottle and the liquid bottle before use.
Respect the recommended dosage: 1 level spoon of powder and 1 drop of liquid.
Separate the powder into two piles on the spatula block to make mixing easier.
Recap powder and liquid bottles after use to prevent evaporation or water absorption.
The principle of spatulation is to “wet” each particle of the powder with the liquid in a minimum of time and over a minimum surface area.
Spatulation time should not exceed 30 seconds.
Add the powder to the liquid in 2 batches for ease. The mixture should be shiny before adding, then it will become opaque.
For pre-dosed capsules:
The capsule is struck to allow the acid and base to come into contact. It is then inserted between the vibrator clamps. The trituration time (8 seconds) is that recommended by the manufacturer.
The capsule is finally placed in the gun, 2 or 3 presses on the piston will allow the material to arrive at the end of the transparent applicator.
3- Placing the material, condensation and sculpture :
The contribution can be made in one go or in several times depending on the clinical situation. It is not necessary to put it in place in successive thin layers unlike the composite.
4- Roughing of the CVI : Use diamond burs with ogival and flame profiles to perfect the anatomy. Check the interfaces
composite-enamel (no under- or over-contours).
ADHESIVE RESTORATIVE THERAPEUTICS
ADHESIVE RESTORATIVE THERAPEUTICS
5- Finishing and polishing the CVI :
Use of red ring diamond cutters (finer grains).
Use of polishing discs with increasingly finer grains (increasingly lighter colours).
In proximal restorations (site 2), polish the proximal area using an abrasive strip without damaging the contact point.
6- Application of the protective varnish : The varnish limits the dissolution caused by water absorption until the material has completely set, which requires several hours.
D-Direct restorations to compomers :
The role of compomers in restorative dentistry remains uncertain and requires further clinical studies to identify their indications and to determine the situations in which they may produce better performance.
The lower fluoride release and the requirement to use an adhesive system before applying the restorative material. Therefore, the indications will be more similar to those of microfilled composites.
Compomers are indicated for erosive/abrasive lesions in visible areas. However, in this latter indication, compomers have not yet demonstrated their clinical superiority over composite resins.
The operating technique:
Selection of shades
Remove external dental plaque or surface stains.
Beveling and die-stamping
Tooth conditioning/dentin pre-treatment, adhesive application
Application of pre-dosed Compomer Restorative Material in Compules Tips: Load the Compules Tip Gun with pre-dosed Compules Tips.
Adapt, shape contours and form with appropriate composite instruments.
Light-curing: Light-cure each area of the restoration surface with a visible light lamp.
Finishing and polishing.
ADHESIVE RESTORATIVE THERAPEUTICS
ADHESIVE RESTORATIVE THERAPEUTICS
E-Indirect techniques : ceramic vestibular veneers
These ceramic veneers have unmatched aesthetic and mechanical qualities, especially when using new generations of adhesives and high-performance bonding materials.
However, their disadvantages are irreversibility, because once the veneer is fixed, any subsequent correction is impossible; as well as the relatively high cost of their production.
The operating protocol:
ADHESIVE RESTORATIVE THERAPEUTICS
a-Preparation of the tooth : the steps of this preparation are:
Anesthesia
Laying a retraction wire
Preparation of deep guide grooves
Enamel preparation of 0.7 mm maximum.
The free edge will be shortened by approximately 1 mm.
Preparation of the peripheral palatal groove: it facilitates the placement of the ceramic.
Impression taking: For impression taking, an elastic material (polyether or silicone A) will preferably be used.
Creation of a temporary restoration: either using a direct composite vestibular veneer or a finished crown.
b-Laboratory technique : this is the creation of the veneer while respecting the treatment objectives, namely the shape and the color.
c-Adhesive fixing
d-Polishing and finishing.
ADHESIVE RESTORATIVE THERAPEUTICS
ADHESIVE RESTORATIVE THERAPEUTICS
IV-2 – The different techniques for restoring posterior teeth :
A- Direct composite restorations :
Intended for small and medium-sized tooth loss in permanent premolars and molars: Lesions site 1 and 2 stages 2 and 3.
The main techniques for direct restoration on posterior teeth are:
Single mass or block technique
The lamination or composite-up technique
The so-called sandwich or dentin substitute technique
And currently a new technique is proposed: it is the Mixed Technique: in block and dentin substitute
A-1 Single mass or block technique : Simple but results in uncontrolled shrinkage during polymerization.
To model the occlusal face, the practitioner must work the composite more or less by subtraction, which creates porosities but above all a morphology that is difficult to achieve.
Setting contraction is minimal in cases where the volume of the composite is reduced.
In the case of large cavities, the setting contraction can detach the composite from the tooth walls, hence the need to establish a technique which places small quantities of composite in multiple layers (strata).
A-2 The stratification or composite-up technique :
The composite can be laid in horizontal layers (Horizontal stratification) or oblique layers (Oblique stratification).
A more precise technique is introduced: composite up technique:
The technique requires construction under a dam and involves 4 stages:
1. Cavity preparation and dentin hybridization to effectively protect the dentino-pulp complex.
2. Placement of an interdental wedge and a thin, curved metal matrix to facilitate the creation of contact points.
3. After reconstruction of the proximal faces, placement of a chemo-polymerizable fluid composite on the base of the cavity (2/3 cervical) in order to accelerate the restoration procedure and limit the constraints associated with polymerization withdrawal.
4. Restoration of the occlusal portion : The technique involves a multilayer method, each layer of which is light-cured for 3 seconds. Once the occlusal portion is in place, the surface of the restoration is finished by applying and light-curing (40 seconds) a thin layer of flowable composite to reduce microcracks.
A- 3 The Sandwich technique :
The sandwich technique is a mixed restoration technique, combining a dentin substitute (CVIMAR, flowable-auto, dual or bulk- or biodentine composites) with composite resins.
A-4 Mixed technique : Currently, with some bulk modelable composites, practitioners can use a mixed technique (in block and dentin substitute) with restricted contributions (in general, 2 layers of 4 mm each), which limits the operating time with a single material going up to the occlusal surface with another composite.
The surface is modeled by composite instruments and by subtraction.
B-Semi-direct composite restorations :
Semi-direct techniques are those that allow an inlay to be performed on the chair in a single session, unlike indirect techniques which require two sessions.
Semi-direct techniques are done either intra-orally or extra-orally requiring impressions.
ADHESIVE RESTORATIVE THERAPEUTICS
B-1 Semi-direct intraoral technique (direct composite inlays)
This technique is indicated for the restoration of one or two teeth at the same time at most.
The inlay is made in the same session without going through laboratory steps.
After modeling and photopolymerization of the composite in the mouth, the inlay is removed and the proximal anatomy, if necessary, is corrected and refined.
After firing and light-curing treatments in a special oven, the restoration can be bonded with composite resin cement.
B-2 Semi-direct extra-oral technique (indirect composite inlays) :
Composite inlays and onlays can be performed chairside , with the involvement of extraoral steps. This method is best indicated for the restoration of large intracoronal cavities (occlusal and proximal cavities).
This technique is based on the preparation of the composite restoration on a silicone model obtained from an impression . Unlike the intraoral technique, the walls must have a divergence of only 10°, allowing a more conservative method during cavity preparation .
A silicone model is prepared and the dies are separated with a scalpel.
The inlay is made on the model: a dentin composite is applied to the floor of the preparation. An enamel composite is used to build the proximal wall, and a layer of enamel composite is placed occlusally.
During the same session, the inlay is placed in the cavity for a fitting in the mouth.
After adjustment, the inlay is permanently bonded to the tooth.
C- Indirect restorations : Composite or ceramic inlays-onlays Indirect restoration is the set of reconstructions of substance losses which are made outside the oral cavity after taking impressions and making the prosthetic piece in the laboratory.
This type of restoration requires clinical steps in several sessions and laboratory steps.
Indications:
Width of the preparation greater than 1/3 in both transverse and antero-posterior directions (1/3 for premolars, we can go up to ½ for molars, it will depend on the coronal height and the shape of the tooth), importance of the residual walls.
Cervical bonding joint if possible on the enamel (best situation), at worst on the dentine and at the very worst on the cementum.
Multiple restorations with multiple touchpoints
Complex cavities that are difficult to access due to dental malpositions or vestibulo-lingual misalignment (especially 1st and 2nd molars)
SiSta 1.3 / 1.4/ 2.3/ 2.4
Operating protocol : 2 clinical stages and 1 provisional stage.
We talk about inlays but we are most often led to create inlays and onlays with cusp coverage when we have a very thin residual wall which risks breaking if we keep it.
Cavities: shapes and preparation:
Maximum respect and conservation of dental tissue
Conservation of overhangs
Cavity with morphology easy to manage in the laboratory
Compensation for undercuts, we create a flat bottom (not by cutting healthy tissue but by adding CVI or composite flow material).
Persistence of sufficient thickness at the level of all the walls (1.5 mm for the composite and 2 mm for the ceramic). It is the morphology of the carious destruction which will guide the morphology of the cavity.
Edges: short oval bevel of 1 to 1.5 mm. Cylindrical or cylindro-conical burs are never used, all preparations are made with rounded edges in the form of a fillet without right angles or shoulders (this is to promote the wettability of the materials imprinted in the cavity and also the wettability of the glue).
Impression taking (hydroalginate, silicone with a moderately compressive technique because we do not touch the soft tissue, we do not need to push back the gum. We favor a single-manipulation technique such as double mix, alginate, single-phase and therefore no wash technique because of the repositioning problem).
Taking the shade (dentin, enamel, cervical).
Creation of the provisional ( photopolymerizing provisional inlay sealed with eugenol-free cement).
ADHESIVE RESTORATIVE THERAPEUTICS
Laboratory procedure:
Casting the plaster impression: obtaining an MPU
We mark limits with wax pencil
Insulator/separator on the model
Mounting the dentin layers: starting from the central layers at the level of the groove with saturated shades +1.5 to +2 compared to the base shade, the further you go to the surface the less saturated the layers are and the closer you get to the shade chosen initially.
Cervical shade assembly
Mounting the cusp tips
Occlusal control
Enamel tint and surface effect
Polishing, silicone wheels, polishing paste
Polymerization in a conventional light enclosure, or light enclosure under an Argon or CO2 type atmosphere, or enclosure containing liquid and under temperature.
Dental tissue adhesion procedure
Bonding protocol: under dam with etching and adhesive
At the inlay level: sandblasting of the surface for all types of inlays, etching with hydrofluoric acid for ceramic inlays, silanization of the intrados for composite and ceramic inlays (in order to resolve post-polymerization problems).
The choice of composite glue: regardless of the brand and range, what is important is to strictly respect the manufacturer’s bonding protocol. And the choice can be personal in relation to the ease of handling of one brand more than another.
Finishing the joints
Joint quality is very essential in bonding techniques
Touch up the joint as little as possible with cutters.
Polishing with silicone wheels under spray (never dry) and then with polishing pastes with decreasing grain size (from 5-7 micro to 0.5-1 micro).
5) Adhesive restorations on non-vital teeth
The evolution of adhesive techniques has allowed the emergence of new principles in the treatment of devitalized teeth.
Clinical and radiological evaluation of residual dental tissues should allow the clinician to choose the most appropriate and least iatrogenic technique for the tooth.
In cases of small volume (access cavity) to moderate loss of substance on teeth with recent pulp loss, our choice should be composite adhesive restorations or glass-ionomers “sandwich technique”.
The surgical protocol remains unchanged except for a few opinions which incriminate dehydration of the devitalized tooth, hence the absolute necessity of wet bonding.
In the case of more significant loss of substance: The preservation of dental tissues but also the risks inherent in each stage of the creation of a post and its sealing must lead to a careful assessment of whether the placement of a root post is really necessary to reconstruct a devitalized tooth.
In fact, in some cases, teeth without root anchorage are considered to be significantly more resistant.
For this, the surgical technique is the same as for living teeth; adhesive restoration is the treatment of choice and also exploits the access cavity to increase the retention and resistance of the restoration.
If the tooth is weakened by the presence of several cavities or by significant loss of substance, the installation of a root anchor must be considered.
Conclusion
The study of natural teeth, knowledge and understanding of the physical phenomena that govern the circulation of light have given access to a modern dimension of conservative dental medicine: biomimetics.
This discipline not only contributes to the development of the materials themselves, it also aims to integrate existing materials into a rational approach that includes biology, biomechanics and aesthetics.
The current state of knowledge directs restoration protocols towards adhesive technology, tissue economy and bio-integration of the material into its environment.