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Fiber post reconstruction. Update and clinical protocol

Adhesive reconstruction of dental structure has become the new standard since the 90’s. Many aspects of the treatment were modified in order to make such reconstruction more feasible, predictable and long-lasting.
Advantages of such approach can be summarized as followed:
Good esthetics, thanks to the tooth-like color making such restorations compatible with glass ceramic crowns.
Biological, as adhesion allows for more conservative preparation of the post space to achieve retention.
Mechanical, due to the significant improvement regarding stress distribution along the root instead of being concentrated at the bottom of the metal post. This homogeneity created between the dentin, adhesive system, core build-up and fiber post can create «all-in-one» concept.
The purpose of this article is to present through a clinical case the updated clinical concept for fiber post reconstruction in order to make it accessible in the everyday practice.

old crown on upper right incisor style italiano styleitaliano

Fig.1
This female 35-year-old patient had old crown placed five years earlier on tooth 11. She was looking for a new restoration with «less opacity and grey color in the cervical area».
To achieve a highly aesthetic result, we decided to replace the old crown and the old restoration underneath, and to perform connective tissue grafting to get thicker cervical gum.

old abutment restoration style italiano styleitaliano

Fig.2
After the removal of the crown a short preparation and corroded tooth structure were found.

discolored abutment style italiano styleitaliano

Fig.3
The old bulid-up was removed and a the tooth structure was cleaned to prepare it for efficient bonding.

large fiber post space style italiano styleitaliano

Fig.4
A large endodontic access was found. In this case, a finer post restoration will also improve the mechanical behavior of the tooth.

isolation of juxtagingival abutment style italiano styleitaliano

Fig.5
The rubber dam is positioned to perfectly isolate the tooth from the biological fluids (saliva and blood).

clean post space under rubber dam isolation styleitaliano style italiano

Fig.6
When the loss of structure is in the juxta gingival position it is highly recommended to use dental floss to isolate this area by pushing the rubber dam inside the sulcus. Therefore the practitioner should have a clear peripheral occlusal vision in which all margins are visible.

abutment buildup matrix styleitaliano style italiano

Fig.7
A core shape matrix is used to guide the shape and homogeneity of the core build-up material.

try in of double fiber post style italiano styleitaliano

Fig.8
Because of the width of the root canal preparation, a double post (LuxaPost DMG) restoration can be an interesting option to reduce the volume of composite more significantly, and thus the polymerization stress of the core build-up. The more the composite volume, the higher the contraction. This is why two small diameter fiber can be preferrable to one big fiber diameter.
Moreover, bis-GMA resin embedded fibers are our first choice to reinforce the connection with the core build-up.

try in of single fiber post styleitaliano style italiano

Fig.9
A larger fiber post was also tried. In both cases the mechanical key point is the freedom of the fiber in the root to avoid adjustments. This is what is called passive post to let the core build-up resin between the dentin wall and the fiber and offer the mechanical advantages described previously.

shortening of fiber post styleitaliano style italiano

Fig.10
In order not to damage the fiber when reducing the length of the post, a diamond disk is recommended. Diamond burs destroy the fibers.

try in of fiber post height style italiano styleitaliano

Fig.11
After shortening the fiber posts, the core shape is checked again for marginal fit. After the try-in, the posts are placed in alcohol for 15 seconds. As fiber posts are already pre-silanized, the adhesive is placed (LuxaBond Universal, DMG) and then light cured.

etching of abutment before bull dup style italiano styleitaliano

Fig.12
Phosphoric acid etching for 45 sec is applied in order to compensate the reduction of tubular dentin in the root, even though the manufacturer recommends 15-20 seconds only.

endodontic microbrush with bonding agent style italiano styleitaliano

Fig.13
A dual-cure Adhesive system (LuxaBond Universal DMG) is applied with a dedicated micro-brush for the root access to improve friction in the root. After drying to remove excess bonding, a 30 seconds are left to let the chemical curing process. Then a 45 second light exposure is performed.

injection of build-up seal cure composite styleitaliano style italiano

Fig.14
A universal mixer tip with bendable metal tip is used (Colibri breakable plus Sulzer Mixpac) to inject the dual cure composite (LuxaCore Z DMG) inside the root and simultaneously in the core form to get the ideal homogeneity between the root and the coronal part.

composite build up with flowing excess material style italiano styleitaliano

Fig.15
A 3-second spot cure is applied to remove the cervical excess. Then it is important to wait the setting time of the dual cure core build up for 2 minutes until it reaches a plastic phase. Only after this previous setting time a light curing of 1 minute is recommended. Why? To avoid a massive stress of polymerization due to the important volume of injected resin. This is the reason LuxaCore Z (DMG) is suitable for this core build-up technique.

provisional resin crown styleitaliano style italiano

Fig.16
A provisional crown was fabricate using a new generation of solid syringeable resin (LuxaCrown DMG).

gingival tissue grafting style italiano styleitaliano

Fig.17
In order to improve the thickness the keratinized gingiva and to prevent the grayish color from being seen through the marginal gingiva, a connective tissue graft was placed in the cervical area with flapless technique to be minimally invasive.

provisional crown and gums after connective tissue grafting style italiano styleitaliano

Fig.18
After one week the healing of the gum is not complete, but we can already see the integration of the graft.

final ceramic crown on upper right incisor style italiano styleitaliano

Fig.19
One month later, the final crown is cemented and is well integrated. As you can see, the pink volume is only slightly modified.

Fig.20
Three years later we can note proliferation of the graft which overlapped on the ceramic. This phenomenon is frequent with connective tissue graft and has to be fixed with delicate gingivectomy to lengthen the crown back to the ideal proportion.

Conclusions

Fiber post reconstruction has esthetic, biologic and mechanical advantages. The preservation of the remaining structure is mandatory, therefore the clinical protocol has to be followed strictly as any bonding protocol. The cleaning of the surface, the selection of the fiber post, the choice of adhesive system, the quality of injection , type of core built up resin, residual wall and the clinical protocol are key factors which will make your restoration the best possible one.

Bibliography

1. Diana H, Oliveira J, de Lara Ferro M, Silva-Sousa Y, Gomes E. Stress Distribution in Roots Restored with Fiber Posts and An Experimental Dentin Post: 3D-FEA.Braz Dent J . Mar-Apr 2016;27(2):223-7.

2. Nahar R, Mishra SK, Chowdhary R. Evaluation of stress distribution in an endodontically treated tooth restored with four different post systems and two different crowns- A finite element analysis. J Oral Biol Craniofac Res. 2020 OctDec;10(4):719-726. doi: 10.1016/j.jobcr.2020.10.004. Epub 2020 Oct 9.

3. Zarow M, Vadini M, Chojnacka-Brozek A, Szczeklik K, Milewski G, Biferi V, D’Arcangelo C, De Angelis F. Effect of Fiber Posts on Stress Distribution of Endodontically Treated Upper Premolars: Finite Element Analysis. Nanomaterials (Basel). 2020 Aug 29;10(9)

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