Complex reconstructions

Complex reconstructions

Plan

1. Introduction
2. Definitions
3. Retention
   1. Definition 
   2. Intrinsic retention  
   3. Extrinsic retention 
4. Dentin posts 
   1. Definition 
   2. Criteria for choosing a dentin post
   3.  Benefits 
   4. Disadvantages

5. The different types of tenons 

5.1. Sealed tenons 

5.1.1. Advantages

5.1.2. Disadvantages 

2. Friction tenons 
   1. Benefits 
   2. Disadvantages 
   3. Indications 
3. “Self-drilling” screwed tenons  
   1. Benefits 
   2. Contraindications:
4. Root posts: (Pulpless teeth)

1. Definition 
2. Metal root posts  
3. Fiber root posts 
4. Carbon fiber tenons 
5. Quartz fiber tenons
6. Fiberglass Tenons 

7. Complex reconstructions on living anterior teeth 
   1. Operating protocol 
   2. Self-curing composite restoration  : 
   3. Light-curing composite restoration  :
8. Complex reconstructions on living posterior teeth:
   1. Operating protocol 
9. Complex reconstructions on devitalized teeth:
   1. Operating protocol

Conclusion

Bibliographic references

Complex reconstructions

1. Introduction :

Caries is an infectious disease that causes progressive destruction of the hard tissues of the tooth. This process ultimately results in irreversible loss of substance.

The practitioner will be required to perform simple or complex fillings depending on the degree of loss of substance.

2. Definitions:

• Simple cavity: this is a cavity that affects only one side of the tooth and takes the name of the side concerned.
• Compound cavity: this is a cavity that involves two faces.
• Complex cavity: involves at least 03 coronal walls, or the only residual part of the dental organ does not ensure stability or retention of the material.
• Simple restoration: This is a restoration that does not require the use of extrinsic retention devices and relies solely on intrinsic effects by replacing the absent tissues with materials.
• Complex restoration: this is a restoration where the residual anatomical elements alone cannot ensure the retention of the filling material and require extrinsic retention means. 

3. Retention
4. Definition  : Retention is the set of forces that oppose the tearing away of structures in contact. A cavity is said to be retentive if:

• It ensures a mechanical union of the shutter in the three directions of space.
• It provides immobilization in three directions perpendicular to each other.

2. Intrinsic retention  : Uses the self-retention of the cavity. These means of retention are:

• Dentin pits
• The grooves 
• The grooves
• Cusp coverings.

3. Extrinsic retention  : Uses external devices such as:

• Dentin posts
• Root tenons
• Or both at the same time.

4. Dentin posts: (On living teeth):
5. Definition: it is a cylindrical or conical metal rod (steel or titanium), threaded or grooved, of small diameter, inserted precisely into a well previously calibrated using a drill in the dentine.
6. Criteria for choosing a dentin post  : it must ensure good retention which is proportional to:

– The depth of the well which must be > 2mm.

– Their number varies from 1 to 4 depending on the dilapidation

– Their diameter varies depending on the dilapidation

– The thickness of the dentine required for the placement of a dentin post must be equal to 03 times the diameter of the post.

– The drilling points are located at the intercuspal level and are parallel to the external surface of the tooth.

– The free part of the tenon is curved according to the requirements of the occlusion.

4.3. Advantages:

– Tissue preservation

– Restoration can be carried out in a single session.

– Significant increase in the retentive value of the cavity.

– Possible increase in resistance form.

4.4. Disadvantages:

-Their placement can create areas of weakness or cracks in the dentin.

– Presence of hiatus (microleakage) around the tenons.

Complex reconstructions

5. The different types of tenons:

5.1. Sealed posts  : they are sealed with a Zn carboxylate or oxyphosphate cement in the wells, prepared in the dentine with a diameter slightly larger than that of the post.

1. Benefits  :

– The tenon can be tested and curved as desired before final insertion and sealing.

– Available in several diameters.

– Their fixing is based on the sealing cement.

The rods are not likely to fracture a weakened tooth.

2. Disadvantages:

• Difficult execution technique.
• Retention is much less satisfactory.

2. Friction tenons:

 They are held by friction in the wells < 0.025mm to that of the tenon with a depth of about 2mm. Their retentive value is 2 to 3 times higher than sealed tenons.

1. Benefits :

• Easy technique
• Inexpensive instrument.
• Low caliber.

2. Disadvantages:

• Its use on posterior teeth presents a certain complexity.
• Contraindication to a test and reinsertion into the well.
• Appearance of cracks following the installation of the tenon.

3. Indications:

• Anterior teeth.
• Small volume posterior teeth.

5.3. “Self-drilling” screwed tenons: their diameter is 0.03 to 0.01 mm < that of the tenon. They exist in 03 dimensions:

– “Regular” tenons screw diameter = 0.8mm and drill diameter = 0.65mm.

– “Minim” tenons screw diameter = 0.57mm and drill diameter = 0.53mm.

– “Minikin” tenon screw diameter = 0.45mm and drill diameter = 0.43mm.

They are fitted using a contra-angle (8000 rpm) and screwed in using a hand wrench.

1. Benefits :

• Easy technique
• Much higher retention
• Tenons can be cut or curved.
• The gap around this type of tenon is less.

2. Contraindications:

• Anterior teeth (aesthetic order)
• PM and M of reduced morphology.

6. Root posts: (Pulpless teeth)
7. Definition  : 

It is a metal or fiber rod with a pointed or threaded end topped with a cast head, inserted into a root canal, treated and prepared for this purpose.

2. Metal root posts  : 

They can be made of stainless steel, gold-plated steel or titanium. They are of different lengths and sections. They can have a shape: cylindrical, conical or cylindro-conical. They are either: screwed, sealed or screw-sealed. Titanium tenons have high mechanical resistance, they are biologically neutral and the phenomenon of corrosion is reduced.

• Presentation  : these tenons come in the form of a box including:

• Tenons of variable section and length.
• Calibrated drills for preparing the tenon housing.
• A chuck
• A key for screwing the tenon

3. Fiber Root Posts  : There are three types of fiber posts: carbon fiber post, quartz fiber post, and fiberglass post.
4. Carbon fiber tenons:

• Are made of an epoxy resin matrix with 64% carbon fiber
• Their diameter is 7 µm
• These are double-conical, cylindrical-conical tenons with a beveled end.
• No “electrochemically stable” corrosion, easy removal and less stress on periodontal tissues.

5. Quartz fiber tenons  : 

Are made of a modified, transparent epoxy resin matrix with quartz fibers. 

• The tenon is translucent and aesthetic
• They can have a cylindrical or conical shape.
• They have the same modulus of elasticity as dentin, hence the risk of fractures is reduced. 
• They are radiopaque
• They are bonded with a composite resin that chemically bonds to epoxy resin and are compatible with self-curing or dual-curing adhesives and sealing composites.

6. Fiberglass Tenons  : These are bundles of fiberglass braided in a multiaxial arrangement, with a composite binder, providing high resistance to bending and torsion.

• They have a cylindrical shape with a long apical cone
• Aesthetic and white, easy removal from the canal
• Physicochemical compatibility and perfect bond between the post, the cement and the dentin
• Color coded for perfect identification.

Complex reconstructions

7. Complex reconstructions on living anterior teeth:
   1. Operating protocol:

• Preliminary X-ray 
• Local anesthesia 
• Operating field
• Cavity preparation
• Choice of tenon and the number which will depend on the importance of the loss of substance
• It is placed 0.5 mm from the enamel-dentine junction
• Length: will depend on the depth of the cavity
• Their orientation: it must fit into the volume of the reconstruction and be placed parallel to the root wall to avoid any perforation.

• Creation of the dentinal well: using a round bur, a guide notch at the location marked for their position
• Drilling the housing using a low-speed drill bit, up to the maximum depth of the latter in one go to avoid widening the well.
• Positioning and fixing the tenon: it is placed on the contra angle, exerting light pressure, associated with a low rotation speed which will allow the tenon to fix itself and cut automatically
• Checking the stability of the tenon
•  Installation of the protective base
• Tooth restoration.

2. Self-curing composite restoration  : 

Either Angulus dies or Celluloid molds are used.

 Using the Angulus Matrix:

• For IV cases, the Angulus matrix is ​​cut and then adjusted so that it extends over the beveled part by 1 mm.
• A transparent wooden wedge blocks the cervical part

Using the Odus mold:

• The choice of mold is made according to the size and shape of the tooth to be treated.
• Adjustment of the mold by referring to the height of the symmetrical tooth.
• It is drilled at the proximo-incisal angle to allow excess composite to escape to avoid air bubbles during compression.
• The mold is then filled with previously prepared composite, then placed under pressure and the excess is removed.
• After the composite has set, the mold is removed by cutting it using a turbine cutter.  
• Finishing the composite while checking the occlusion;
• Polishing using discs with different grain sizes.

3. Light-curing composite restoration  :

• In this case the restoration will be done with a smooth strip, since the cavity is filled in successive layers while polymerizing each layer using a polymerization lamp.
• Finishing is polishing of the composite, with verification of the occlusion.

8. Complex reconstructions on living posterior teeth:
   1. Operating protocol:

• Preliminary radio
• Anesthesia
• Setting up the operating field

• Cavity preparation: removal of unsupported enamel and fragile walls
• Number of tenons is a function of the loss of substance (one tenon/cusp missing).
• The post must be located 0.5 mm from the enamel-dentine junction, taking into account: the length from which its coverage by the material must be 2 mm)
• They must be adjusted to fit within the volume of the restoration.
• They must be parallel to the root wall to avoid any perforation.
• Creation of the dentinal well (steps already mentioned).
• Restoration with silver amalgam: a metal matrix and matrix holder are used if the damage is not too severe. If the lesion is very extensive, copper rings for the formwork are used.
• The choice of these rings is made according to the extent of the lesion, the diameter will be slightly less than that of the tooth to maintain the ring.
• Adjust the ring using a pair of scissors, taking care not to damage the gum at the cervical level, and while respecting the height of the occlusion.
• Identification of the vestibular and palatal faces for the correct orientation of the ring.
• After the ring is adjusted, the edges are polished so as not to injure the gum and to properly crimp the tooth at the neck.
• The ring is placed and it is wedged by two interdental wedges at the proximal level.
• Amalgam restoration, left in place for 24 to 48 hours.
• After this period, the ring is cut using a turbine cutter and then removed.
• Sculpture and polishing of amalgam.

Complex reconstructions

9. Complex reconstructions on devitalized teeth:

Retention at the level of devitalized teeth is ensured by root posts. If the decay is very significant, dentin posts can be added to increase retention. 

1. Operating protocol:

• An X-ray is taken to check the tightness of the root canal filling.
• Setting up the operating field
• Removal of the temporary filling

• Edge correction and residual wall evaluation.
• Visualization of the canal orifices.
• The choice of the location of the root post which must be made at the level of the most robust root (the palatine canal for the upper molars and the distal canal for the lower molars).
• The choice of the root tenon: its shape and length will be chosen according to the root anatomy (the cylindro-conical tenon is best suited to the root anatomy

Complex reconstructions

• Preparation of the root post housing  : it must respect

• Obturation of the apical third
• Should be done on half the canal length (5 to 8mm)
• The canal is unobturation manually using a large diameter pin with a stop using a solvent or using a GATES drill bit. This unobturation is completed by a drill bit corresponding to the chosen tenon.
• Trying out the tenon: it must enter its housing freely and without friction.
• Its coronal length must be at least 2 mm. 
• The tenon must be covered with a sufficient thickness of material for better stress distribution.
• The head must be clear of the walls of the cavity. 
• Tenon sealing: using polycarboxylate, Zn oxyphosphate or glass ionomers.
• The walls are induced with cement, then the tenon is placed on the mandrel by coating its end with cement and brought to the level of the canal.
• In the case of a screwed tenon, the screw must be tightened ¼ turn and no more to avoid any risk of fracture.
• Remove excess cement and wait for the cement to harden.
• Final restoration either with amalgam or composite, following the entire protocol cited above.

Complex reconstructions

Conclusion

 The reconstruction of pulped and depulped teeth is a delicate but necessary procedure to maintain the dental organ in function.

This construction uses different techniques. The elements of choice and the limits are clearly codified. They thus make it possible to objectively guide the therapeutic choice.

The decision, arises from a logical analysis dictated by the clinical parameters and

radiographic while taking into account the physico-mechanical, retentive and biological qualities of the materials

Complex reconstructions

Bibliographic references

1.   L ASFARGUES JJ – Conservative restorations of devitalized teeth. Réal. Clin., 1: 211-221, 1990.

2. M OUNT GJ and HUME WR – A new classification of

cavities. Clinic, 18 (8): 457-463, 1997.

3.   Robert PA, Compagnon D. Conororadicular reconstructions of devitalized teeth. Therapeutic choices. Prosthetic Strategy. 2006; 6:175-182.

5. B rouillet JL, Koubi S. Bonded coronal root reconstructions and fiber-based tenon. Cah Prothese. 2001; 116:51-59.

Complex reconstructions

Untreated cavities can damage the pulp.
Orthodontics aligns teeth and jaws.
Implants replace missing teeth permanently.
Dental floss removes debris between teeth.
A visit to the dentist every 6 months is recommended.
Fixed bridges replace one or more missing teeth.
 

Complex reconstructions