|Year : 2016 | Volume
| Issue : 3 | Page : 97-100
Restorative management of grossly mutilated molar teeth using endocrown: A novel concept
Sarika Chaudhary1, Ashok A Rathod1, Pankaj Yadav1, Sangeeta Talwar1, Mahesh Verma2
1 Department of Conservative Dentistry and Endodontics, Maulana Azad Institute of Dental Sciences, New Delhi, India
2 Department of Prosthodontics, Maulana Azad Institute of Dental Sciences, New Delhi, India
|Date of Web Publication||10-Aug-2016|
Dr. Sarika Chaudhary
Department of Conservative Dentistry and Endodontics, Maulana Azad Institute of Dental Sciences, New Delhi
Source of Support: None, Conflict of Interest: None
The endocrown is a restorative option for endodontically treated teeth. It consists of a circular butt-joint margin and a central retention cavity inside the pulp chamber and lacks intraradicular anchorage. Endocrowns are formed from a monoblock containing the coronal portion integrated into the apical projection that fills the pulp chamber space and possibly the root canal ingresses. This article describes the rationale and clinical guidelines for the placement of endocrowns. In the cases presented, extensively damaged teeth were superseded with endocrowns composed of pressed ceramics (Empress 2, Ivoclar), following endodontic and periodontal therapy. The substructure of this technique is to utilize the surface available in the pulpal chamber to assume the stability and retention of the restoration through adhesive procedures. By eliminating the utilization of a post and filling core, the number of adhesive bond interfaces is reduced, thus making the restoration less susceptible to the adverse effects of degradation of the hybrid layer. In these clinical cases, the 24 months survival of the endocrown restoration may be considered prosperous.
Keywords: Endocrown, laser, nonvital teeth
|How to cite this article:|
Chaudhary S, Rathod AA, Yadav P, Talwar S, Verma M. Restorative management of grossly mutilated molar teeth using endocrown: A novel concept. J Res Dent 2016;4:97-100
|How to cite this URL:|
Chaudhary S, Rathod AA, Yadav P, Talwar S, Verma M. Restorative management of grossly mutilated molar teeth using endocrown: A novel concept. J Res Dent [serial online] 2016 [cited 2018 Dec 14];4:97-100. Available from: http://www.jresdent.org/text.asp?2016/4/3/97/188235
| Introduction|| |
Restoration of mutilated endodontically treated tooth is always a challenge due to higher risk for biomechanical failure than a vital tooth. The loss of structural integrity associated with caries, trauma, and extensive cavity preparation leads to reduction in stiffness and fracture resistance of endodontically treated tooth.  The type of restorative materials used and kind of restoration that conserves tooth structure have great influence on the prosperity of the treatment. 
The remaining tooth should be restored congruously as it acts as a platform for the renovation and influences the overall strength of the restored tooth.  The classical approach in such cases would be the utilization of post and core, which has physical properties proximate to those of natural dentin, utilizing adhesive procedures, and subsequent placement of a full-coverage crown.  Several studies support the utilization of post based on the clinical outcomes.  However, many studies have also quoted the risk for contingent root perforation and subsequent root fracture during the post-space preparation.  Therefore, the need for better restorative technique is of prime consequentiality for management of such arduous cases.
With the progress in technology, the need for the macro-retentive design like post is no longer a requisite for restoration of badly damaged tooth. Endocrowns have emerged as good restorative alternative in teeth with short, obliterated, dilacerated, or fragile root.  It is a total porcelain crown well adapted to root canal treated tooth, thus obtaining macromechanical retention (provided by the pulpal walls), and microretention (by utilizing adhesive cementation). It may also be utilized in situations of excessive loss of coronal dental tissue and limited interocclusal space, in which it is not possible to procure adequate thickness of the ceramic covering on the metal or ceramic substructures.  Reinforced, acid-etchable dental ceramics have been the materials of cull for the fabrication of endocrowns because of superior mechanical and bond strength.
Teeth with insufficient coronal tooth structure may require additional vertical ferrule and surgical recontouring of the hard and soft tissues for retention of the restoration. Lasers are currently proving very efficacious in a broad range of restorative and esthetic procedures, including crown lengthening.  Crown lengthening availed with laser technology is less invasive than utilizing a scalpel and high-speed handpiece to accomplish the same end result. The main advantages of utilizing a dental laser over conventional surgery include minimal or no bleeding, detailed control of tissue abstraction, rapid wound rejuvenating, and minimal postoperative discomfort. 
The present case report describes the utilization of endocrown as an alternative approach for renovating extensively damaged tooth after crown lengthening with a laser.
| Case Report|| |
A 35-year-old female patient reported with extensively damaged tooth in the upper right region of the mouth. She gave a history of previous pain and root canal treatment 4 months back, but her symptoms resolved only temporarily. There were no drug allergies or relevant medical history. Clinical examination showed 16 to be badly destroyed with thin remaining walls [Figure 1]a. The radiograph revealed poorly obturated mandibular molar [Figure 1]b. On analysis of all the factors, it was decided to retreat the tooth and plan for endocrown restoration. The access cavity was modified by means of Endo-Z bur (Dentsply Maillefer, Ballaigues, Switzerland). Coronal flaring was accomplished with Gates-Glidden burs (sizes 3 and 4) (Dentsply Maillefer). Old gutta-percha and sealer was removed by means of rotary ProTaper retreatment files and Endosolv E (Septodont, New Castle, DE, USA). The apical calcified portion of the root canal was negotiated using C-files (Dentsply Maillefer, Ballaigues, Switzerland) and EDTA (Dentsply Maillefer, Ballaigues, Switzerland). This was followed by usage of 10 and 15 K-files till the apical end. The working length was estimated with an electronic apex locator (Root ZX, J Morita, Tokyo, Japan) and confirmed with periapical radiograph. The canal was instrumented using rotary ProTaper treatment files up to master apical file F3 under copious irrigation, with 5% sodium hypochlorite. After being cleaned and shaped, the canal was dried and obturated by cold lateral condensation of gutta-percha (Dentsply Maillefer) and sealer (AH Plus, Dentsply DeTrey, Konstanz, Germany) [Figure 2]a. As there was insufficient remaining coronal tooth structure, it was decided to undertake a crown lengthening procedure using erbium, chromium: yttrium-scandium-gallium-garnet (Er, Cr: YSGG) laser [Figure 2]b. Local infiltrative anesthesia (lidocaine with epinephrine 1: 100,000) was administered. The patient and staff used special eyeglasses for protection. A scalloped external bevel incision was made using Er, Cr: YSGG laser (Waterlase C100® ). The application (short pulse "H" mode) was done using a 600 μm sapphire tip, 1.5 W, 13% air, and 9% water in noncontact mode. A laser bandage was applied with 0.5 W with air and water switched off. The patient was recalled after 1 week for preparation [Figure 2]c.
|Figure 1: (a) Preoperative radiograph revealing inadequate obturation. (b) Grossly destroyed 16 with missing palatal and distal wall|
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|Figure 2: (a) Postoperative radiograph after retreatment. (b) Crown lengthening procedure on palatal aspect of 16 with laser. (c) Healed palatal aspect after crown lengthening procedure. (d) Impression made using elastomeric impression material|
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After the removal of the provisional restorations, preparation for endocrowns was initiated on tooth; the pulpal chamber floor was exposed, and appropriate leveling of residual buccal and lingual walls was achieved. The goal in preparation was to achieve an overall reduction in the height of the occlusal surface of at least 2 mm in the axial direction. This reduction can be achieved by drilling 2 mm deep grooves as guides then, using a green diamond wheel bur to reduce the occlusal surface. The bur was oriented along the major axis of the tooth and held parallel to the occlusal plane. The cervical margins were supragingival; however, if clinical factors or esthetics require, the margin can follow the gingival margin. Enamel walls <2 mm thick were removed. A cylindrical-conical green diamond bur with a total occlusal convergence of 7° was used to make the coronal pulp chamber and endodontic access cavity continuous. This step primarily involved eliminating undercuts in the access cavity. With the bur orientated along the long axis of the tooth, the preparation was carried out without excessive pressure and without touching the pulpal floor. Then, retraction cords were placed and an impression made with a polyvinyl siloxane material (President light body and heavy body, Coltene Whaledent) [Figure 2]d. After the impression was poured with hard stone, dies were cut and prepared for the fabrication of models. Provisional restoration was done using Tempron and the patient was recalled after 1 week for cementation of the final restoration.
The final restoration was found to be esthetically good [Figure 3]a and the margins were flushing well with the preparation [Figure 3]b and c. High points and occlusion were checked, the patient was satisfied, and postoperative radiograph was taken [Figure 3]d. The patient was recalled at 1, 6, 12, and 24 months for evaluation.
|Figure 3: (a) Tissue surface of endocrown depicting the core and crown fabricated as single unit. (b) Occlusal view after endocrown cementation. (c) Buccal view after endocrown cementation. (d) Postoperative radiograph after endocrown cementation|
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| Discussion|| |
Factors such as trauma and caries, as well as endodontic procedures, can lead to the excessive flared root canals. Flared canals are then more susceptible to fracture because of thin remaining walls, necessitates the utilization of only those restorative techniques that will not further affect the integrity of remaining tooth structure.  The amount and quality of remaining coronal and radicular structure determine the potential vigor and the retention of core materials and final restoration. Guidelines for the application of endocrowns and other restorative techniques for nonvital posterior teeth have evolved, and indications relate to the integrity of residual tooth structure.
Endocrown is contraindicated if adhesion cannot be assured, if the pulpal chamber is <3 mm deep, or if the cervical margin is <2 mm wide for most of its circumference. The all-ceramic monolithic-type construction made by pressure molding or machining endows the endocrown with good mechanical strength. The butt joint, or cervical sidewalk, is the base of the restoration - with a band of peripheral enamel that optimizes bonding.  The goal is to achieve a wide, even, stable surface that resists the compressive stresses that are most common on molars. The prepared surface is parallel to the occlusal plane to ascertain stress resistance along the major axis of the tooth. The pulpal chamber cavity ascertains retention and stability, and the root canals do not require any categorical shape; therefore, they are not weakened by the drilling and they will not be subject to the stresses associated with the utilization of post.  The compressive stresses are reduced, being distributed over the cervical butt joint and the walls of the pulp chamber. The endocrown fits impeccably with the concept of biointegration and belongs among the restorative options for posterior endodontically treated deplorably damaged molars.
Glass-ceramic because of its excellent biocompatibility and its wear coefficient is proximate to that of the natural tooth is very opportune option for fabrication of endocrown. The bonding material constitutes the crucial interface between the restoration and the prepared tooth. In integration to its adhesive properties, its modulus of elasticity is paramount as it must be able to absorb pressure, just as the dentin-enamel junction does. 
The versatility of the Er, Cr: YSGG laser and its ability to recontour both hard and soft tissues creates the opportunity for a minimally invasive approach in many clinical situations that require repositioning of the periodontal structures for esthetic or restorative reasons. Surgical techniques utilizing the laser also have been shown to decrease the need for suturing, reduce postoperative discomfort, and shorten healing times. The Er, Cr: YSGG laser is an excellent choice for this application as it rapidly removes and recontours the gingival tissues with good hemostasis and also very efficiently removes bony tissue. Er, Cr: YSGG lasers represent an excellent alternative to the classical technique because it causes less postoperative morbidity, the tissue healing is faster, and the wound shows less gingival retraction.  This article demonstrated the use of the Er, Cr: YSGG laser for soft-tissue crown lengthening procedure as part of postendodontic rehabilitation of a mutilated molars.
| Conclusion|| |
The restorative management of endodontically treated teeth has been widely discussed in the literature. Conservation of remaining salubrious dental structures is of prime importance for the stabilization of tooth-restoration complex. Endocrown increases surfaces available for adhesion, therefore impacting positively the treatment long-term prosperity. In this case report, endocrowns were found to be a feasible option to full crowns or composite overlays for the restoration of nonvital posterior teeth, especially those with minimal crown height and sufficient tissue available for stable and durable adhesive cementation.
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[Figure 1], [Figure 2], [Figure 3]