Make sure that the horns of the tooth chamber do not contain pulp residues: Remains of the pulp often cause the discoloration to reoccur sometime after internal bleaching, so it is extremely important to clean this part of the tooth chamber

Creating the barrier: Measure the height of the tooth crown from the labial surface and transfer this length (taking the incisal edge as a reference point) to the tooth chamber; create a barrier within the root canal opening 1 mm below the gingival margin (Fig 10-1a). The barrier should protect the alveolar bone and the gingival attachment from the proximal surfaces, which is why the material should be arch-shaped with more material creating the barrier approximately (Figs 10-1b and 10-1c). What is the best material for the barrier? Unfortunately, it cannot be a composite resin due to the bonding system that would block the dentinal tubules and the diffusion of the whitening agent. Glass-ionomer or traditional phosphate cement remains the best material as they are easy to shape and set rapidly. If it is necessary to use a bur or ultrasonic tip to make adjustments, these two materials are easy to correct.

Fig 10-1a
Barrier design for internal bleaching – the sagittal section shows how the material should be positioned so as not to block the penetration of the whitening agent in the labial direction, along the dentinal tubules.

Fig 10-1b
The arch-shaped barrier protects the alveolar bone and the gingival attachment in the interdental space.

Fig 10-1c
Design of the barrier – frontal section.

Application of the bleaching agent: The material of choice (when it comes to bleaching after root canal treatment) is 10% sodium perborate mixed with distilled water or 3% hydrogen peroxide. This material can be used only outside the European Union as it is prohibited within the bloc (Annex III of the cosmetics directive 76/768/EEC).22 In the European Union, the material of choice is 10% carbamide peroxide, which is routinely used for vital teeth whitening. The problem in this case is the proper application of the carbamide peroxide in the consistency of the gel, so it remains in contact with the labial surface and allows diffusion of the whitening agent along the dentinal tubules.

Closing the whitening agent in the tooth chamber: After cleaning the whitening agent from the edges of the cavity, a small cotton ball is inserted into the chamber, leaving space for 0.5–1 mm of restorative material, such as RelyX Unicem (3M), which is a self-adhesive cement and shows good retention in such cases. The whitening agent should be left in the tooth chamber for a period of 3–7 days.

Replacing the bleaching agent: Depending on the need, the bleaching agent can be replaced once or twice (in total, the bleaching agent can be maximally inserted into the tooth chamber up to three times). The faster the whitening is performed and the fewer consecutive visits to replace the whitening agent, the lower the risk of any possible fracture or cracking. Apart from the effect of the whitening agent itself, a possible weakening of the hard dental tissues may occur during functions such as biting or chewing since the tooth during bleaching is a kind of empty tube susceptible to fractures. Decreasing this risk by reducing the bleaching time and providing the patient with accurate information about the precautions to be taken in connection with the bleaching process are indicated

Application of calcium hydroxide paste for the next 14 days: This raises the pH level that was disturbed during internal bleaching. In addition, the hard dental tissues need at least 2 weeks after whitening to be able to bond adhesively

Tooth reconstruction with a composite resin: 14–21 days after teeth whitening^18–26

Case 1: Discolored non-vital teeth

A female patient presented to the dental office in order to improve the esthetics of discolored teeth 11 and 12 (Figs 10-2a and 10-2b). The placement of four porcelain veneers improved the symmetry of the entire smile, along with diastema closure between the central incisors and resolution of the discoloration problem. However, the patient expected a less invasive solution and an attempt was performed to whiten discolored teeth 11 and 12 internally and obtain composite veneers without preparation.

Figs 10-2a and 10-2b
Intraoral photographs of the patient who presented to the dental office in order to improve the esthetics of teeth 11 and 12.

Step 1: Root canal retreatment

The quality of root canal fillings in teeth 11 and 12 was assessed (Fig 10-2c), and a decision was taken to perform endodontic retreatment. During the treatment, attention was paid to the remnants of the pulp horns of the tooth chamber (a common cause of discoloration) (Fig 10-2d). Retreatment was performed by filling the root canals with thermoplastic condensable gutta-percha (System B, Obtura) (Figs 10-2e and 10-2f).

Fig 10-2c
Radiograph of teeth 11 and 12 after root canal treatment shows that the root canals are probably filled with pastes, and the filling material is not reaching the apex – so endodontic retreatment should be performed.

Fig 10-2d
In tooth 12, visible pulp remnants are located in the horn of the tooth chamber.

Figs 10-2e and 10-f
(e) Retreatment: filling the root canals with thermoplastic condensable gutta-percha (System B). (f) Radiograph of teeth 11 and 12 taken after endodontic retreatment.

Step 2: Bleaching the discolored teeth

A glass-ionomer cement barrier was created (Fig 10-2g), and a bleaching agent (Fig 10-2h) – sodium perborate mixed with 3% hydrogen peroxide (other bleaching agents must currently be used in the European Union) – was applied into the tooth chamber.

Fig 10-2g
Clinical situation after applying the barrier in teeth 11 and 12.

Fig 10-2h
Bleaching agent applied in the chamber of teeth 11 and 12.

The clinical situation after the first whitening session is shown in Fig 10-2i, and after the second one in Fig 10-2j. Next, impressions were taken for the whitening splint (Fig 10-2k). At the following appointment, while keeping the barrier (Fig 10-2l) and with an open pulp chamber from the palatal surface, “inside-outside” bleaching was performed involving the simultaneous use of the bleaching agent (10% carbamide peroxide) inside and outside for 3 days (Fig 10-2m). The modified whitening splint had special openings on the adjacent teeth (Fig 10-2n) to facilitate the removal of excess bleaching agent (Fig 10-2p), so they would not be whitened accidentally. The final result after whitening is shown in Fig 10-2o.

Fig 10-2i
Clinical situation after the first bleaching session – visibly brightening teeth, compared to the initial situation.

Fig 10-2j
Clinical situation after second bleaching session – evident brightening of teeth 11 and 12 compared to the initial situation.

Fig 10-2k
Alginate impression was taken to create a splint and carry out the “inside-outside” bleaching technique.

Fig 10-2l
The barrier was sealed to ensure perfect tightness of the root canals.

Fig 10-2m
The patient was informed how to apply the bleaching gel (10% carbamide peroxide) into the tooth chamber …

Fig 10-2n
… and externally into the whitening splint. Whitening was recommended for the next 3 days with the recommendation of great caution when consuming foods.

Fig 10-2o
Clinical situation after ­completing bleaching of the teeth with root canal ­treatment.

Fig 10-2p
Agents used in the walking bleach technique: (from left) sodium perborate, which should be mixed with 3% hydrogen peroxide or with distilled water; 35% hydrogen peroxide is not recommended in any situation (due to risk of external cervical resorption); 10% carbamide peroxide, which at the moment remains as the material of choice in European Union under the new regulations.

Step 3: Removal of the old composite restorations and obtaining new restorations

Two weeks after the whitening procedure was completed (for this period, calcium hydroxide was placed into the tooth chamber), the restorative phase could be completed. The teeth were isolated with a rubber dam, and the old composite resin restorations were removed (the rubber dam certainly made this easier) with diamond burs, microabrasion, and a scalpel (Figs 10-2q to 10-2t). The clinical situation immediately before the final restorative phase is presented in Figs 10-2u and 10-2v. After thorough air abrasion and etching with orthophosphoric acid (Fig 10-2w), the bonding system was applied. The inside of the tooth chamber was filled with a very bright opaque flowable composite (Essentia ML, GC) (Fig 10-2x) and a layer of a bright dentin composite (UD1 Micerium) (Fig 10-2y).

Fig 10-2q
Rubber dam isolation was placed to better recognize the old restoration margin while removing the fillings.

Fig 10-2r
Removal of the old restorations with a small ball-shaped diamond bur with increasing speed red band 1:5 contra-angle handpiece.

Fig 10-2s
Microabrasion with 27 µm particles of aluminum oxide.

Fig 10-2t
Removal of the remaining subgingival excess material by a scalpel no. 12.

Fig 10-2u
Clinical situation after removing the majority of the old composite resin.

Fig 10-2v
A visible chamfer in tooth 11 – the clinical situation after air abrasion of the labial surface.

Fig 10-2w
Etching the labial ­surface of the teeth with ­orthophosphoric acid.

Fig 10-2x
Filling cervical part of the tooth chamber with very bright opaque flowable composite resin.

Fig 10-2y
Placing a very bright dentin layer.

Using an enamel layer of composite resin (BF2, Micerium) and the silicone index, the palatal wall was formed (Fig 10-2z) and then, with the matrix bands for premolars (Quickmat Sectional Matrix, Polydentia) placed perpendicularly, the proximal surfaces were created (Fig 10-2aa). In tooth 11, a Class 4 cavity was restored with dentin composite (UD3, Micerium). After that, a veneer matrix was fixed (Unica Anterior, Polydentia) (Figs 10-2bb and 10-2cc), and the inverted U-shaped “frame” was carried out with a flowable composite (G-aenial Universal Flo, GC), and final enamel layer (BF2, Micerium) was applied inside the “frame” (Fig 10-2dd). The shaping of the veneer was performed with the Profin contra-angle handpiece (Figs 10-2ee and 10-2ff) and a diamond bur no. 832-204-012 (Komet Brasseler) in order to achieve symmetry with the adjacent central incisor (Figs 10-2gg and 10-2hh).

Fig 10-2z
Reconstruction of the palatal surface with enamel composite and silicone index.

Fig 10-2aa
Clinical situation after reconstructing the proximal surface with the enamel composite.

Fig 10-2bb
Unica Anterior Matrix (Polydentia) was adapted with wooden wedges …

Fig 10-2cc
… and, after applying a flowable composite (G-aenial Universal Flo, GC), it was polymerized, and the matrix band was removed. This is how the “frame” was created to facilitate the application of the final layers.

Fig 10-2dd
Situation after applying the external enamel layer on tooth 11 and after restoring tooth 12.

Figs 10-2ee and 10-ff
The veneers were shaped appropriately with a Profin contra-angle handpiece.

Figs 10-2gg and 10-2hh
The shape was performed with a diamond bur no. 832-204-012 (Komet Brasseler).

When the shape was similar to the symmetrically located tooth, characterization was performed. Vertical lines were drawn with a pencil, corresponding to the vertical grooves of the adjacent tooth, and recreated on the composite veneer using a bur no. 832-204-012 (Figs 10-2ii and 10-2jj). Then, the horizontal lines were drawn and appropriate characterization was performed with the same bur (Figs 10-2kk and 10-2ll). The final result is shown in Fig 10-2mm. Photographs taken on a follow-up visit show the natural integration of composite resin restorations into the patient’s smile and the surrounding hard and soft tissues (Figs 10-2nn to 10-2pp). In the meantime, in order to further improve the esthetics, the diastema was reduced through a composite microrestoration of tooth 21 and internal bleaching of discolored tooth 42.

Fig 10-2ii
In order to perform an appropriate characterization, vertical lines were drawn with a pencil, corresponding to vertical grooves …

Fig 10-2jj
… next, the characterization of the vertical grooves of the adjacent central incisor was transferred on the veneer.

Fig 10-2kk
Then, with a pencil, the horizontal characterizations were drawn corresponding to the adjacent central incisor …

Fig 10-2ll
… and adequately delicate horizontal grooves were performed with a diamond bur no. 832-204-012 (Komet Brasseler).

Fig 10-2mm
The final result of ­reconstructing teeth 11 and 12 after internal ­bleaching and endodontic retreatment.

Fig 10-2nn
Intraoral photograph of ­composite restorations 11 and 12 taken from a ­semi-profile.

Figs 10-2oo and 10-pp
(oo) Intraoral photograph before starting the treatment and (pp) the patient’s smile from semi-profile view (restored teeth after internal bleaching and endodontic retreatment).

In conclusion, it is worth emphasizing that the bleaching effect can be extremely beneficial, facilitating the composite as a restorative material. This, in turn, allows simpler and faster implementation of an esthetic restoration, which can also be less invasive.

Case 2: Discolored non-vital teeth

A female patient presented to the dental office to improve the shape and the color of tooth 21 (Figs 10-3a to 10-3c). She expected that the tooth’s esthetics would be improved with an all-ceramic crown. A radiograph was taken, revealing that discolored tooth 21 had undergone root canal treatment. A less invasive procedure was planned in the form of internal bleaching and, in the case of a positive result of bleaching, a direct composite restoration was planned.

Figs 10-3a to 10-3c
Extraoral and intraoral photographs of the patient who presented to the dental office to improve the esthetics of discolored tooth 21.

Step 1: Root canal retreatment

Endodontic retreatment was carried out due to the old root canal endodontic paste (Figs 10-3d and 10-3e), which was not favorable to maintain the bleached color of the tooth in the future (one of the reasons for recurrence of the discoloration are the old endodontic pastes containing dyes).

Fig 10-3d
Radiograph of the discolored tooth. The root canal is filled properly, but the filling material is a paste, which may pose a risk of discoloration reoccurrence after bleaching.

Fig 10-3e
Radiograph of tooth 21 after root canal retreatment. Root canal filled with thermoplastic gutta-percha.

Step 2: Bleaching the discolored tooth

In the next stage, internal bleaching was performed under the procedures described in Case 1, making a barrier (Fig 10-3f), and applying the sodium perborate in three following appointments into the pulp chamber (Fig10-3g). A direct composite resin veneer could be planned since the bleaching gave a positive result (Fig 10-3h). If the whitening procedure had been unsuccessful, the patient should have been offered two indirect veneers on the maxillary central incisors.

Fig 10-3f
A barrier was obtained in the root canal opening before starting the internal bleaching of tooth 21.

Fig 10-3g
After applying the bleaching agent (sodium perborate mixed with 3% hydrogen peroxide) into the pulp chamber – palatal view.

Fig 10-3h
Clinical situation after ­completing the bleaching (three ­sessions).

Step 3: Replacing the old fillings and a fiberglass post cementation

Two weeks after the bleaching, restorative treatment was carried out. A provisional restoration was performed to simulate the tooth’s final shape, and a silicone index was taken (Fig 10-3i). The teeth were isolated with a rubber dam, all old restorations were removed (Fig 10-3j), and a white fiberglass post was cemented (Ena Post, Micerium) (Figs 10-3k to 10-3o). The reason to cement a fiberglass post was the unstable occlusion in the posterior segment (risk of future anterior overloading) and to enhance the fluorescence effect of the final composite restoration.²³

Fig 10-3i
A provisional composite restoration was performed in order to take a silicone index for further tooth reconstruction.

Fig 10-3j
Two weeks after completing the bleaching, the restorative phase was started. The teeth were isolated with a rubber dam, and the old restorations were removed.

Fig 10-3k
The appropriate space for the fiberglass post was prepared, with the root canal dentin being airborne-particle abraded with aluminum oxide 27 µm, and etched with orthophosphoric acid.

Fig 10-3l
… after rinsing thoroughly, the root canal was dried with paper points …

Fig 10-3m
… the appropriate size of fiberglass post was selected …

Fig 10-3n
… and the post was adjusted, so it does not extend beyond the volume of the final reconstruction …

Fig 10-3o
… next, the bonding system was applied, and the fiberglass post was cemented.

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