AUTHORS: Izabella Kaczmarczyk, Borys Tomikowski
ABSTRACT: Endodontic treatment, regardless of the cause that led to it, results in a significant loss of hard tooth tissues. The aim of prosthetic rehabilitation of endodontically treated teeth is to restore the anatomy and strengthen its structure to minimize the risk of cracking or fracture. A major challenge is to obtain a tight restoration that will permanently protect the filled root canals from access by bacteria in the oral cavity and strengthen the remaining tooth structure. Endocrowns are one of the methods of restoring teeth with dead pulp. This restoration uses a large surface of the tooth chamber, which is stabilization and the adhesive cementation method ensuring appropriate microretention. Endocrown is an alternative to the classic reconstruction of endodontically treated teeth using post-and-core posts and crowns. In the era of commonly used adhesive cements, even with significant destruction of supragingival structures, especially molars, it is possible to obtain a strong and stable connection in time.
KEY WORDS: endocrown, endodontically-treated teeth, adhesive restoration
ARTICLE PUBLISHED: March 24, 2023
- Thanks to the possibility of adhesive anchoring in the tooth chamber, the endocrown has become a good alternative in the prosthetic treatment of endodontically treated teeth.
- Endocrowns eliminate the risk of excessive tissue loss and unintended root canal perforation.
- Root canals are not additionally widened, and the preparation procedure for an endocrown is less traumatic compared to the preparation for a post and core and a prosthetic crown
The aim of prosthetic rehabilitation of endodontically treated teeth is to restore their anatomy and strengthen their structure to minimize the risk of cracking or breaking . A major challenge is to obtain a tight restoration that will permanently isolate the filled root canals from the access of bacteria in the oral cavity and strengthen the remaining tooth structure.
Before deciding on endodontic treatment of a tooth, it is necessary to determine the possibility of its later reconstruction, ensuring appropriate tightness and strength. If such reconstruction is impossible, the entire treatment is doomed to failure. One of the most common causes of tooth loss after properly performed endodontic treatment is its incorrect conservative or prosthetic reconstruction (1, 2).
The weakening of an endodontically treated tooth is caused by physical changes occurring in the dentin as a result of its dehydration and a significant loss of hard tooth tissues. Factors that should be taken into account when planning the final restoration include: the amount of hard tooth tissues remaining after treatment, the position of the tooth in the arch, aesthetic requirements and occlusal forces acting on the tooth. Until now, the treatment method of choice was restoration using a post and core and a crown. The development of materials science and minimally invasive adhesive techniques has allowed the use of microretentive bonding forces without the need for aggressive preparation ensuring mechanical retention. Thanks to the possibility of adhesive anchoring in the tooth chamber, the endocrown has become a good alternative in the prosthetic treatment of endodontically treated teeth (3, 4).
Indications for the use of endocrowns
The main indication for the use of endocrowns are molars with dead pulp. Clinicians confirm that of all tooth groups, it is molars that allow for the best results in maintaining such a restoration. This is mainly due to their anatomical structure, large chamber surface compared to other tooth groups, which allows for stable anchoring in a wide chamber and root canal orifices (5). It is believed that endocrowns transfer chewing forces more evenly compared to teeth restored with post-and-core posts and crowns. Moreover, by replacing a post-and-core post with an endocrown, we avoid the risk of excessive weakening of the tooth core and root perforation during its preparation.
Moreover, in specific clinical situations where the use of post and core implants is impossible, such as obliterated, narrow or too short root canals, significant canal curvature or broken instruments that cannot be removed, endocrowns will be the only alternative (6).
There is no clear position on the use of endocrowns in the reconstruction of endodontically treated premolars. These teeth have a smaller adhesive bonding surface and a higher crown that adversely affects mechanical properties. Additionally, the forces acting on these teeth in the case of group management can cause the reconstruction to be balanced. With preserved vestibular and lingual walls and correct occlusal conditions, this method of reconstruction can bring good results, which is why each case should be analyzed individually.
Another indication for the use of endocrowns are teeth with low crowns, when there is no space in occlusion for the use of a classic reconstruction with a post and a crown (7–10).
This type of restoration is not recommended when the pulp chamber is shallower than 3 mm. In such cases, too small a surface may not provide sufficient retention. Also, when the wall is lower than 2 mm, the use of endocrowns is risky, as it may result in its cracking or breaking. An unfavorable prognosis also occurs in the case of deep cavities on the contact surfaces, resulting in difficult access and the inability to maintain the dryness necessary in adhesive techniques of cementing prosthetic works. Other contraindications to the use of endocrowns include coexisting occlusal overloads, periapical changes that are not amenable to endodontic and surgical treatment, as well as high caries activity and poor oral hygiene. These restorations are also not recommended for young patients (1, 11, 12).
Endocrown materials
Materials used in the production of endocrowns are mainly feldspathic ceramics, leucite ceramics and lithium disilicate. Laboratory composites are less popular, but cheaper to produce. The economic aspect is the only advantage of choosing this material. In comparison to ceramics, they are characterized by high polymerization shrinkage, and consequently, the risk of leakage at the endocrown-tooth interface, caused by a marginal gap. In addition, they have lower compressive strength and abrasion resistance (13).
Benefits and advantages and disadvantages of using endocrowns
The use of ceramic endocrowns brings many benefits. High aesthetics, less complicated procedure and shorter time of its execution, compared to classical reconstruction using post-and-core posts and crowns, are the basis for choosing this reconstruction method. The costs incurred by patients are also reduced. Endocrowns also eliminate the risk of excessive tissue loss and unintended perforation of the root canal. The treatment is reversible, it allows for easy, repeated revision of the canal system in the event of symptoms from the treated tooth (14).
It should also be emphasized that endocrowns have a significant advantage over common composite restorations, which are still a common method of long-term restoration of endodontically treated teeth. Greater tightness and precision of indirect restorations, especially in the area of contact points, due to the fact that they are made outside the oral cavity and the possibility of direct insight into the area of contact and gingival surfaces, speak in their favor. Covering the cusps of the tooth, which are most susceptible to damage, precise reconstruction of the chewing surface of the tooth and full inclusion of the tooth in the process of chewing food are other advantages of endocrowns (15, 16).
The disadvantages of endocrowns include, first of all, the difficult cementation procedure, especially in the case of subgingival destruction of the tooth, which may consequently lead to marginal leakage, decementation of the work, or even fracture of the tooth crown. Based on studies conducted on molars, it has been proven that the decementation of the endocrown is not influenced by the construction of the restoration, but by the place where the force is applied. A more favorable stress distribution was observed when the forces were applied closer to the tooth-restoration border. It is worth remembering that the best adhesion is not achieved with the enamel, which is why it is necessary to leave as much enamel core as possible on the periphery of the tooth to ensure a stronger connection. It should be emphasized that these restorations are characterized by lower strength compared to traditional restoration on a post and core. In the case of discolored teeth, it should be taken into account that the final aesthetic effect may be unsatisfactory in the case of incomplete coverage of the vestibular wall (7, 8, 9, 10).
Preparation of tooth tissue for endocrown
The preparation of tooth tissue for an endocrown differs from the preparation of tissue for conventional crowns. This monolithic ceramic adhesive restoration requires special preparation techniques to fulfill all biomechanical functions. The preparation of a tooth for an endocrown can be achieved in a simple and quick way.
First, remove caries and all composite fillings. Then reduce the nodules by 2-3 mm, remembering that the remaining supragingival walls should be at least 1.5-2.0 mm wide and 2.0 mm high. A 1.0 mm wide chamfer should be made. The tissue preparation into the pulp chamber should measure 3.0-4.0 mm, and the axial walls should be set divergently towards the chewing surface. Additional retention can be obtained by removing gutta-percha from the coronal part of the canal to a depth of no more than 2 mm. At the end of the preparation, smooth all edges and walls. The supragingival position of the cervical edge protects the marginal periodontium and facilitates taking a precise impression. The forces are distributed between the axial walls and the cervical step, thus reducing the load on the chamber floor. The root canals are not additionally widened, and the preparation procedure itself is less traumatic compared to the preparation for a post and core post and a prosthetic crown (11, 12).
Summary
Endocrown is a promising alternative for the reconstruction of endodontically treated molars. It allows for the preservation of a greater amount of hard tooth tissue, in accordance with the idea of minimally invasive dentistry. This type of tooth reconstruction is still rarely used by clinicians, but this tissue-saving type of reconstruction should be considered every time. Treatment with the use of post-and-core composite direct restorations or inlay/onlay fillings can be replaced with endocrowns in many cases.
BIBLIOGRAPHY:
1. Fages M, Bennasar B: The endocrown: A different type of All-Ceramic reconstruction for molars. J Can Dent Assoc 2013; 79:d140.
2. Żarow M.: Endoprosthetics. Guide for practice. Published as odbudowa Kwintesencja, Warsaw 2013, 5, 6, 103.
3. Dzieciątkowska M.: Endocrown of a tooth after root canal treatment – a method of treatment for everyone. Mag. Stomatol., 2013, XXIII, 3, 76–83.
4. Mannocci F., Cavalli G., Gagliani M.: Adhesive restorations of endodontically treated teeth. Kwintesencja Publishing House, Warsaw 2008, 44, 47.
5. Rumińska M, Zarzecka J: Contemporary methods of prosthetic reconstruction of teeth treated with root canal – a review of the literature. Implantoprotetyka 2007;
6. Żarow M, Steinder J: Reconstruction strategies of posterior teeth after endodontic treatment based on a clinical case. Annales Academiae Medicae Stetinensis Annals of the Pomeranian Medical University in Szczecin 2009;
7. Lin CL et al.: Evaluation of failure risks in ceramic restorations for endodontically treated premolar with MOD preparation, Dent. Materials, 2011, 27, 5, 431–438.
8. Lin CL et al.: Estimation of the risk of failure for an endodontically treated maxillary premolar with MODP preparation and CAD/CAM ceramic restorations. J. Endod., 2009, 35, 10, 1391–1395.
9. Lin CL: Estimation of the failure risk of a maximal premolar with different crack depths with endodontic treatment by computer-aided design/computer-aided manufacturing ceramic restorations. J. Endod., 2013, 39, 3, 375–379.
10. Lin CL et al.: Finite element and Weibull analyzes to estimate failure risks in the ceramic endocrown and classical crown for endodontically treated maxillary premolar. Euro. J. Oral Sci., 2010, 118, 1, 87–93.
11. Żarow M, Steinder J: Reconstruction strategies of posterior teeth after endodontic treatment based on a clinical case. Annales Academiae Medicae Stetinensis Annals of the Pomeranian Medical University in Szczecin 2009; 55 (2): 53–58.
12. Shillingburg HT, Hobo.D.: Fixed dentures. Outline of clinical and laboratory procedures, Kwintesencja Publishing House, Warsaw 1997, 83–85, 98, 163
13. Dzieciątkowska M.: Reconstruction of a tooth after root canal treatment with an endocrown made of composite material. Kerr news, 2013, 3, 16–17.
14. Dejak B.: Finite element analysis of the effort and bonding with tissues of ceramic endocrowns in molars. Protet. Stomatol., 2008, LVIII, 3, 151–1615.
15. El-Damanhoury HM, Haj-Ali RN, Platt JA: Fracture resistance and microleakage of endocrowns utilizing three CAD-CAM blocks. Oper Dent 2015, 40 (2): 201–210.
16. Pryliński M., Majewski S.: Prosthetic reconstruction of teeth after endodontic treatment. Elamed, Katowice 2013, 7-8.
Authors:
DENTAL DOCTOR IZABELLA KACZMARCZYK
1st Clinic of Prosthodontics, Medical University of Lodz.
DR. N. MED. BORYS TOMIKOWSKI
1st Clinic of Prosthodontics, Medical University of Lodz.
Article published on March 24, 2023.
