Contraindicated internal bleaching: What to do?
Before reconstruction of a root canal treated anterior tooth, the walking bleach technique should always be considered. If the treatment plan includes a prosthetic crown, the aim of internal bleaching is to improve in the colour around the cervical area and coronal portion of the root. These details will determine the final aesthetics within the gingival area. The walking bleach technique is therefore the procedure of choice in such cases. The protocol of internal bleaching was carefully described in the article “Non-Vital Tooth bleaching” published on StyleItaliano (http://www.styleitaliano.org/maciej-zarow-non-vital-tooth-bleaching). The most popular and the safest material for this purpose is still that which has been used routinely in clinical practice for several decades. This is, a paste prepared ad hoc, composed of sodium perborate and 3% H2O2 or distilled water. This article presents a case report of the aesthetic treatment in a case of a severely discoloured root canal treated tooth, where there was a contraindication for internal bleaching.
What are the contraindications for internal bleaching?
The most important factor in bleaching effectiveness seems to be precise removal of all restorative materials from the access cavity without additional dentin elimination. Dentin has to be cleaned in order to facilitate diffusion of the bleaching agent through the dentinal tubules. If a fiber post was cemented in the root canal and the pulp chamber was filled with composite resin, removing the restorative material and post can compromise the amount of sound dentin. Therefore, such a case calls for careful evaluation of aesthetic benefits vs. structural sacrifice. Other contraindications for internal bleaching include:
discolourations caused by amalgam or other metallic materials (not bleachable)
Significant dentin loss in the cervical portion (risk of fracture and leakage of bleaching agent)
Visible cracks, especially with subgingival extension (risk of bleaching agent penetrating towards periodontal ligaments)
Young patients (<19 years old) A 31-year-old male patient presented in our dental clinic in order to improve the aesthetics of a severely discoloured root canal treated right central incisor (Img. 1-4). Discoloration had been present for more than 10 years, and previous treatment had included fiber post placement. The discoloured tooth had two old composite resin III-class restorations: mesial one, and distal one, and additionally slightly worn incisal edge (Img. 3). The patient was deprogrammed using the Kois Deprogrammer, for four weeks. Minor premature occlusal interferences in posteriors were removed (the patient was occlusally equilibrated). The root canal obturation performed in the past was acceptable. The treatment plan did not consider internal bleaching, as the fiber post had been cemented in the past. The walking bleach technique would, in this case, require the removal of sound structure, thus creating structural risk. Therefore the aesthetic treatment without intervention into the pulp chamber was planned. External bleaching with 6% hydrogen peroxide (Novon technology, Optident) was carried out on the upper and lower arch (Img. 5-7). Three weeks after external bleaching, the composite restorations were replaced and two porcelain veneers were considered to be the best possible treatment option in this case. It can be concluded that three main benefits arose from the above-mentioned treatment plan: 1. It is easier to mask severe discoloration using laboratory techniques; 2. It is much more predictable to perform two symmetrical veneers on two central incisors, than a single, asymmetrical one with unpredictable aesthetic outcome 3. We could improve the symmetry of anterior guidance with the veneers (benefiting function) A digital smile design (DSD) plan was created and sent to the laboratory so that a wax-up could be created (Img. 8). Then the temporary resin mock up was made, and presented to the patient in order to discuss the final outcome (Img. 9). After the patient’s acceptance, two upper central incisors were prepared for porcelain veneers with the use of a silicon index in the horizontal and vertical planes (Img. 10-12). An impression was taken using polyvinyl-siloxane material (Flexitime, Hereus), and the dental laboratory created two feldspathic porcelain veneers. At the next appointment the porcelain veneers were tried in by means of glycerin gel (Img. 13). Then the porcelain was etched with 10% HF for 90 s and cleaned in an ultrasonic bath (5 min). Finally, silane was applied to the dried porcelain surface in several layers, and one coat of adhesive resin was applied followed by gentle thinning with air. After rubber dam isolation the porcelain veneers were cemented simultaneously with the composite resin cement (Img. 14-18).
Img. 1 – The photo of the patient’s smile.
Img. 2 – Upper and lower anteriors during static occlusion.
Img. 3 – Palatal view of upper central incisors.
Img. 4 – Lips in the rest position.
Img. 5 – Upper and lower anteriors in static occlusion after bleaching therapy.
Img. 6 – The photo of anterior guidance after bleaching therapy.
Img. 7 – Upper anteriors after bleaching therapy.
Img. 8 – DSD plan before wax up.
Img. 9 – Mock up procedure (on the right) made based on DSD and wax up.
Img. 10 – Teeth preparation with silicone guide (horizontal plane).
Img. 11 – Teeth preparation with silicone guide cut at different levels.
Img. 12 – Teeth preparation with silicone guide (vertical plane).
Img. 13 – Porcelain veneers try in (with glycerin gel).
Img. 14 – Porcelain veneers after cementation.
Img. 15 – Porcelain veneers after cementation – profile view.
Img. 16 – Patient’s apperance after two porcelain veneer therapy.
Img. 17 – Upper central incisors after porcelain veneers cementation – palatal view.
Img. 19 – Patient’s smile before (left) and after (right) treatment.
In cases where the internal bleaching technique compromises the remaining tooth structure, other options, such as porcelain or composite veneers should be considered.
It is much easier and more predicable to perform two symmetrical porcelain veneers than a single, asymmetrical one.
Although it may seem counterintuitive, performing two symmetrical additive veneers in fact results in a more conservative approach. Simultaneous increase of buccal volume results in decreased enamel reduction.