Miranda Fernández, Juan Pablo¹; Quintero Sifuentes, Roberto¹; Duhalt Iñigo, Daniel¹; Ríos Szalay, Enrique¹

Language: English/Spanish [Versión en español]
References: 15
Page: 206-213
PDF size: 280.47 Kb.

ABSTRACT

Endocrowns are indirect restorations that, through bonding to dentin with polymeric cements, can rebuild and restore a tooth with a single component of various materials, mainly ceramic. Very favorable results in posterior teeth have been reported, considering them a more conservative alternative to reconstruction with endopost-core and its restoration with a complete crown. Requirements to carry them out are a tooth with successful root canal treatment, at least 3 walls with a minimum height of 2 mm, a thickness of 3 mm, and pulp walls with angles from 5^o to 8^o. This paper presents three clinical cases of endocrowns in teeth with a different diagnosis, materials used, and prognosis.

INTRODUCTION

Endodontically treated teeth might have different characteristics and properties than those of vital teeth in terms of structure, strength, integrity, and hydration.

For several reasons, the tooth structure loss, including its wear during preparation for rehabilitation, affects its firmness, reduces its fracture resistance, and consequently limits its prognosis.¹ According to Meyenberg,² Shemesh,³ and Kishen⁴ this loss directly predisposes to the formation of fissures or cracks in both enamel and dentin.

Fissures in turn can cause fractures weakening (due to extensive and rapid removal of tissue during root canal treatment or during endopost placement) produced by excessive interaction with irrigants or intracanal medications (such as sodium hypochlorite and calcium hydroxide) corrosive effects of some restorative materials (such as excess acid etching) and excessive occlusal forces, whose effect is reinforced by the reduction of proprioception exhibited by devitalized teeth.^2-4

PRESENTATION OF CLINICAL CASES

With the improvement and development of polymeric bonding to enamel and dentin in more than 60 years of study,⁵ it is possible to rely on the marginal sealing, retention, and stability of indirect restorations, partial or total. This is the way endocrowns arose, unitary posterior adhesive restorations that span up to the walls of the pulp chamber in a single block, replacing intracoronal reconstructions and total restorations. Among the materials available for its realization there are ceramics, resins, and silicates study (

Table 1).⁶

Endocrowns are mainly indicated for teeth with a little coronal remnant. Biomechanical principles indicate that the tooth structural strength depends on the amount and proportion of the remaining tissues and the integrity of the anatomical shape. Variations in tissue quality after endodontic treatment were shown to have a non-significant influence on the biomechanical behavior of the tooth.^7,8

Endocrowns do not require more than 3 mm occlusal height to offer the properties of conventional crown preparations, so limited interocclusal space is not an obstacle to their usage.^7,9

Endocrowns are also indicated in cases of the roots of teeth in which endoposts do not offer a favorable prognosis due to curvatures in the middle third or dilacerations, very narrow, very wide or C-shaped canals, or in cases of surgical accidents with large tissue loss, such as chamber floor perforations.⁶

In situations of severe loss of coronal tissue, the main option is a post-core treatment, but this one decreases the resistance to fractures and requires the removal of healthy tissue, increasing the risk of perforation.^6,9 From a clinical perspective, the endocrown design seems to have practical advantages over post-core restorations: it is cheaper, requires less elaboration time, and there is no resin shrinkage associated with the technique.⁹

Three female patients 45 to 55 years of age were selected, attended the Advanced Restorative Dentistry Specialty of the Postgraduate School of the Facultad de Odontología de la UNAM, with different clinical characteristics, diagnoses, and prognosis, with endodontically treated teeth.

CASE 1

A 46-year-old female patient who consulted about the restoration of pulpless teeth 36 and 37 (Figure 1A) with provisional restorations, recurrent caries lesions, and narrowing of the interocclusal space relative to its antagonists; limited coronal remnant tissue in both teeth, especially in tooth 36 and with a minimum thickness at the level of the furcation. Its extraction is indicated for subsequent implant placement.

Regarding tooth 37, 4 mm high and 3 mm thick in all its walls, an endocrown was determined (Figure 1B). Absolutely isolated, the pulp chamber was prepared to create an occlusal divergence between 5^o and 8^o. It was decontaminated with 5% sodium hypochlorite and undermines were compensated with photocurable resin Filtek^TM Z350 (3M-ESPE^®) creating straight walls. Canal accesses were sealed with polymer cement RelyX^TM U200 (3M-ESPE^®); then an impression was taken with polyvinyl siloxane (PVS) Elite HD + (Zhermack^®) (Figure 1C) and temporary sealing with Systemp Onlay (Ivoclar Vivadent^®) was made. The restorative material of choice was ceromer SR Nexco (Ivoclar Vivadent) due to its characteristics in general and especially for its resilience, fracture resistance, and low cost (Figure 1D).

During the second appointment, the temporary restorer was removed; the cavity was absolutely isolated and then it was cleaned with Consepsis^TM Scrub 2% chlorhexidine paste (Ultradent), the adaptation, and the occlusal height of the restoration were verified and then cemented with RelyXTM U200 (3M-ESPE) cement. The surpluses were removed and after a 3-second pre-polymerization, the insulation was removed. Then, the occlusion was checked with a 12 μm articulating paper. Finally, the polishing was carried out with rubber and polishing paste for resins (Figure 1E-F).

CASE 2

A 48-year-old female patient with secondary Sjögren’s syndrome attended consultation for comprehensive treatment.

To rehabilitate teeth 36 and 37, previous fillings and surrounding caries lesions were removed. In the cervical area of tooth 36 (Figure 2A) a great loss of both coronal and root tissue was evident. With an endodontic diagnosis of asymptomatic irreversible pulpitis, the canal was treated, a conical root and a C-shaped canal arrangement were observed (Figure 2B-C).

Subsequently, given the impossibility of retention of an intraradicular post due to the arrangement of the canals and the thickness of the root walls, it was decided to place an endocrown. The cervical third was sealed with Vitrebond™ (3M-ESPE) light-curing glass ionomer (Figure 2D).

At the next appointment, the intrapulpal walls and the compromised lingual area were shaped with a frusto-conical bur 856 (Figure 2B), all remaining fragile tissue was removed and the coronal preparation was completed. Afterward, the impression was obtained with VPS Virtual^® XD (Ivoclar Vivadent) applying ceromer as the final restorative material, and a temporary filling was placed.

During the third appointment, we proceeded with the test and subsequent cementation of the SR Nexco (Ivoclar Vivadent) restoration with RelyX^TM U200 (3M-ESPE) cement; immediately, the surpluses were removed and the occlusion control and final polishing were carried out (Figure 2E).

CASE 3

A 57-year-old female patient consulted for a change due to a mismatch of metal amalgam restorations and metal inlay on teeth 36 and 37, respectively (Figure 3A).

After removing the metal restorations and cleaning them, it was observed that the root canal in tooth 36 needed treatment, due to the diagnosis of asymptomatic irreversible pulpitis.

While the canal was permeabilized, perforation of the pulp floor was produced, which was sealed with a bioactive dentin substitute based on tricalcium silicate, Biodentine^TM (Septodont), and the canal treatment was continued, leaving the tooth under observation for a week (Figure 3B).

During the second appointment, the signs and symptoms made it possible to finish the root canal treatment and seal the pulp cavity with a glass ionomer layer of 2 mm thick, Vitrebond^TM (3M-ESPE). Due to the fact that there were few tooth remnants and the impossibility of placing an endopost due to the null existence of axial walls for retention, it was decided to use a lithium disilicate endocrown e.max CAD (Ivoclar Vivadent AG) on tooth 36 and a conventional onlay on tooth 37; then, an impression with (PVS) Elite HD + (Zhermack) was taken and C&B resin was applied to temporary seal (Figure 3C-E).

At the third appointment, the temporary fillings were removed and definitive ceramic restorations were tested, verifying their adaptation, tooth 36 contact areas, interocclusal contacts in centric position, lateral and protrusive excursions. The remaining tissue was then disinfected with 2% chlorhexidine paste Consepsis^TM Scrub (Ultradent). The restorations were etched with 9% hydrofluoric acid porcelain (Ultradent) for 20 seconds,^10,11 neutralization with 35% orthophosphoric acid (3M), and silane placement for 1 minute. Cementation was also done with RelyXTM U200 (3M-ESPE) dual polymeric cement; afterward, surpluses were removed and the necessary occlusion adjustments were made (Figure 3F).

DISCUSSION

The importance of the cases that we present agrees with the parameters proposed by Pissis¹² in 1995 when fabricating metal-free ceramic restorations that encompassed the walls of the pulp chamber in a single block, calling them “endo-crowns”.¹³

Various authors use these principles with great heterogeneity in terms of the technique, methodology, materials used and parameters studied and compared. The main parameters are survival rates, failure models, and clinical criteria.⁶

Having fragile remaining tissue, root canal treatment posterior teeth require a total covering to minimize the risk of fractures, therefore a coronal seal is necessary to prevent bacterial contamination and restore function.¹⁴

Due to various situations, the cases presented were not candidates for conventional endopost-core-crown rehabilitation. For this reason, the parameters proposed by Fages,⁷ Menezes Silva,⁸ Taha,⁹ and Einhorn¹⁴ among others, were followed, performing endocrowns. The restoration was successful in the short term and awaiting medium and long term results such as those obtained by Borgia in 2016 which constituted a 90% success in cases that were monitored for a period of up to 19 years, mentioning that the coronal remnant is the most important factor in the success of endocrowns.¹³

In his 2016 systematic review and meta-analysis, Sedrez-Porto, in five studies, reviewed a total of 102 molars and premolars in which endocrowns of various materials such as ceromers, resins, and ceramics were used with self-etching cement and conventional dual cement. When comparing the results, the different materials did not produce any significant relevance.¹⁵

Regarding studies about teeth with loss of coronal remnant, a lower success was found in not endodontically treated teeth (62%); those in which a fiberglass endopost was used got 80% success^9,14 and the endocrowns got a 90 to 94% success, but more studies are required to confirm the great capacity for success of this technique.^9,15

Relating to the adhesion factor, there is a controversy about the effectiveness of self-etching systems. Some researches show that they provide a dentin bond strength comparable to that obtained with the etching and rinse system, while others have observed a significantly lower bond strength.^6,15

CONCLUSIONS

Endocrowns are an alternative to conventional treatment since they are directed towards the trend of adhesive dentistry that allows being more conservative in situations such as those presented in clinical cases. Knowing its advantages and disadvantages as well as its indications allows treatment to be predictable and ensure long-term success.

REFERENCES

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2. Meyenberg K. The ideal restoration of endodontically treated teeth - structural and esthetic considerations: a review of the literature and clinical guidelines for the restorative clinician. Eur J Esthet Dent. 2013; 8: 238-268.

3. Shemesh H, Lindtner T, Portoles CA, Zaslansky P. Dehydration induces cracking in root dentin irrespective of instrumentation: a two-dimensional and three-dimensional study. J Endod. 2018; 44: 120-125.

4. Kishen A. Mechanisms and risk factors for fracture predilection in endodontically treated teeth. Endodontic Topics. 2006; 13: 57-83.

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7. Fages M, Bennasar B. The endocrown: a different type of all-ceramic reconstruction for molars. J Can Dent Assoc. 2013; 79: d140.

8. Menezes-Silva R, Espinoza CAV, Atta MT, de Lima Navarro MF, Ishikiriama SK, Mondelli RFL. Endocrown: a conservative approach. Brazilian Dent Sci. 2016; 19: 121-131.

9. Taha D, Spintzyk S, Schille C, Sabet A, Wahsh M, Salah T et al. Fracture resistance and failure modes of polymer infiltrated ceramic endocrown restorations with variations in margin design and occlusal thickness. J Prosthodont Res. 2018; 62 (3): 293-297.

10. Puppin-Rontani J, Sundfeld D, Costa AR, Correr AB, Puppin-Rontani RM, Borges GA et al. Effect of hydrofluoric acid concentration and etching time on bond strength to lithium disilicate glass ceramic. Oper Dent. 2017; 42 (6): 606-615.

11. Bajraktarova-Valjakova E, Grozdanov A, Guguvcevski L, Korunoska-Stevkovska V, Kapusevska B, Gigovski N et al. Acid Etching as surface treatment method for luting of glass-ceramic restorations, part 1: acids, application protocol and etching effectiveness. Open Access Maced J Med Sci. 2018; 6 (3): 568-573.

12. Pissis P. Fabrication of a metal-free ceramic restoration utilizing the monobloc technique. Pract Periodontics Aesthet Dent. 1995; 7 (5): 83-94.

13. Borgia Botto E, Barón R, Borgia JL. Endocrown: estudio clínico retrospectivo de una serie de pacientes, en un período de 8 a 19 años. Odontoestomatología. 2016; 18 (28): 48-59.

14. Einhorn M, DuVall N, Wajdowicz M, Brewster J, Roberts H. Preparation ferrule design effect on endocrown failure resistance. J Prosthodont. 2019; 28: e237-e242.

15. Sedrez-Porto JA, de Oliveira da Rosa WL, Fernandes da Silva A, Aldrighi Münchow EA, Pereira-Cenci T. Endocrown restorations: A systematic review and meta-analysis. J Dent. 2016; 52: 8-14.

AFFILIATIONS

¹ Especialidad de Odontología Restauradora Avanzada, División de Estudios de Postgrado e Investigación, Facultad de Odontología, Universidad Nacional Autónoma de México. México.

CORRESPONDENCE

Juan Pablo Miranda Fernández. E-mail: jpmfariad@gmail.com

Recibido: Octubre 2019. Aceptado: Enero 2020.