2018 год

CBCT analyses of advanced cervical resorption aid in selection of treatment modalities: a retrospective analysis

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Abstract

Objectives The selection of treatment for advanced (classes 3 and 4) invasive cervical resorption (ICR) based on a two-dimensional periapical radiograph is challenging. The purpose of the present study is to describe different treatment approaches for advanced invasive cervical resorption based on cone-beam computed tomography evaluation.

Materials and methods All cases of advanced ICR based on CBCT evaluation in our endodontic department between 2011 and 2016 were included in the study. The dimension, circumferential, and coronal-cervical locations of the entry point of the resorption tissue into the tooth were evaluated. The selected treatment approach for each case was documented, and all the data were summarized and analyzed.

Results Twenty-three cases of advanced ICR were included in the study. Approximately, 74% were diagnosed in stage 4, and 26% were diagnosed in stage 3. The narrow entry point was identified in 43% (10 cases), while in 57% (13) of cases, the entry point was wide. Circumferentially, 70% (16) were located on the proximal side. Coronal-cervically, 43% (10) were located more than 1.5 mm above the crestal bone. All narrow entry point cases were treated using a minimally invasive technique, while different treatment approaches were chosen for cases with a wide entry point.

Conclusions The present study proposes different treatment approaches for advanced ICR based on CBCT. The CBCT evaluation of the entry point may facilitate choosing the appropriate treatment approach for advanced ICR cases.

Clinical relevance The description of different treatment approaches for advanced invasive cervical resorption based on cone-beam computed tomography evaluation enables the clinician to choose the optimal treatment approach for each advanced ICR case.

Keywords Invasive cervical resorption ^. Cone-beam computed tomography ^. Minimally invasive treatment ^. Classification

Introduction

Invasive cervical resorption (ICR) is a resorptive dental process that starts with an entry point on the external root surface with the possibility of progression in a coronal-apical direction within the root. Heithersay developed an ICR classification system that divides the condition into four classes according to the extent of the lesion estimated on a periapical two-dimensional radiograph [1]. According to his classification, advanced stages (classes 3 and 4) are characterized by fibro-vascular resorptive tissue extending into the root, accompanied by fibro-osseous bone-like calcifications inside the resorption tissue and the creation of additional resorption channels that burrow deep into the dentin and later interconnect more apically with the peri-odontal ligament through communicating channels. ICR expansion encircles the root canal, and the pulp usually remains unperforated and healthy (uninflamed) due to the presence of a nonmineralized predentin layer [2–4]. However, in long-standing lesions, the advancing resorp-tive lesion may perforate the root canal [2]. The radio-graphic features of such lesions may vary from being well-defined to an irregularly bordered, mottled radiolu-cency, sometimes overlying the outline of the pulp space, with the canal contours remaining distinct [2]. The diag-nosis and management of ICR based on conventional ra-diograph are limited because conventional radiographs are two-dimensional images [5–8]. Cone-beam computed to-mography (CBCT) is a three-dimensional imaging tech-nique that enables evaluating dimension, circumferential location, and coronal-cervical location of the entry point of the resorption tissue into the toot. Therefore, CBCT was found to be superior to periapical radiographs in the diag-nosis and management of ICR [5–8]. Moreover, CBCT imaging has a substantial impact on endodontic decision making, particularly in high difficulty cases [9, 10].

Different treatment approaches for ICR have been de-scribed in the literature [11–18]. Surgical approaches include a flap procedure to allow access to the defect, the mechanical or chemical removal of the resorptive tissue and the placement of dentin-bonded or glass-ionomer cement [12–14]. This sur-gical approach may be accompanied by orthodontic forced eruption of the involved tooth [15]. In long-standing advanced ICR lesions (class 3 or 4), it is very difficult to remove all the resorptive tissue due to the circumferential and coronal-apical extension and additional channels. In addition, a significant amount of bone must be sacrificed, which endangers the periodontal prognosis and crown-root ratio [16, 17]. The exclusive research that studied the prognosis of ICR re-vealed its relationship to the initial extent of the invasive cervical resorption. The researcher concluded that classes 1–3 were treatable, whereas class 4 lesions were not ame-nable to treatment. He suggested that class 4 cases would benefit from alternative treatment options, such as extrac-tion and replacement with an implant-retained crown res-toration [14]. Moreover, a surgical approach should be avoided in patients with, or at risk for, medication-related osteonecrosis of the jaw (MRONJ) [18].

In the last few years, several nonsurgical treatment ap-proaches have been described in the literature. These minimal-ly invasive treatment approaches are based on the mechanical or chemical removal of the resorptive tissue in an internal approach during root canal treatment [19–21].

Recently, several case series have presented the treat-ment of ICR based on CBCT evaluation [20, 21]. Recommendations for choosing the appropriate treatment approach for advanced ICR lesions have never been pub-lished. The purposes of the present study are to describe and discuss different treatment approaches for advanced invasive cervical resorption based on cone-beam comput-ed tomography evaluation.

Materials and methods

The study protocol was reviewed and approved by the Ethics Committee of Medical Corps, IDF (IDF-1684).

All patients who were diagnosed with ICR class 3 or 4 using CBCT in the Department of Endodontics, Israel Defense Forces (IDF) Medical Corps, Tel Hashomer, Israel, between 2011 and 2016 were included in this study.

The CBCT images were displayed using OnDemand3D software (CyberMed, Irvine, USA) in a darkroom. The con-trast and brightness of the images were adjusted using the image processing tool in the software to ensure optimal visu-alization. All CBCT images were analyzed simultaneously by two graduate endodontic residents to reach a consensus for the interpretation of the radiographic findings. In cases of dis-agreement, a third, definitive evaluation was performed by an endodontist with 10 years of experience who was calibrat-ed based on the same criteria and variants.

The data collected from CBCT evaluation included the class of the ICR and the dimension, circumferential location, and coronal-cervical location of the entry point of the resorp-tion tissue into the tooth (Fig. 1). Dimension was classified as narrow (up to 1-mm diameter) or wide (more than 1-mm di-ameter). The circumferential location was classified as proxi-mal or buccal and lingual. The coronal-cervical location was classified as coronal (1.5 mm or more above the crestal bone), cervical (less than 1.5 mm from the crestal bone), or apical (apical to the crestal bone). Different treatment approaches were used in our department for these cases: conservative (minimally invasive) treatment, surgical treatment, and a com-bination of surgical treatment and forced eruption or extrac-tion. Conservative treatment includes endodontic preparation with perforation to area of resorption using irrigation of sodi-um hypochlorite and calcium hydroxide dressing in order to dissolve resorption tissue and combination technique of obtu-ration by gutta-percha and epoxy sealer [21]. Surgical treat-ment includes flap elevation followed by mechanical or chem-ical elimination of the resorption tissue with or without bone grafting and/or periodontal membrane [14].

The selected treatment approach for each case was docu-mented, and all the data were summarized and evaluated.

Results

A total of 23 cases of advanced ICR that were evaluated by CBCT were identified between 2011 and 2016. Twelve cases were in maxillary incisors and canines, eight cases were in mandibular molars, and the other three cases were in a maxil-lary premolar, mandibular premolar, and mandibular incisor. Seventeen cases (74%) of ICR were diagnosed as stage 4, and six cases (26%) were diagnosed as stage 3 according to Heithersay’s classification (Table 1). Class 3 was found only in the maxillary incisors and canines and in the mandibulary molars.

The entry point of the resorption into the tooth was narrow (less than 1-mm diameter) in ten cases (43%), while in 13 cases (57%), the entry point was wide (greater than 1-mm diameter).

Fig. 1 CBCT evaluation of entry point in advanced ICR. a, b Narrow, distal, and cervical. c, d Narrow, distal, and coronal. e, f Wide, mesial, and cervical. g, h Narrow, palatal, and cervical

Table 1 Class 3 and class 4 distribution

	Class 4	Class 3
Maxillary incisors	8	1
Maxillary canines	2	1
Maxillary premolars	1	0
Maxillary molars	0	0
Mandibular incisors	1	0
Mandibular canines	0	0
Mandibular premolars	1	0
Mandibular molars	4	4

Table 2 The chosen treatment approaches for narrow and wide entry points

	Narrow entry point	Wide entry point
Minimally invasive approach	10	4
Surgical approach		5
Surgical + orthodontic eruption		2
Extraction		2
Total	10	13

Examination of the circumferential location of the entry point revealed that in 16 cases (70%), the entry point was on the proximal side (mesial or distal side), and in seven cases (30%), it was on the lingual and buccal sides.

Evaluation of the coronal-cervical location revealed that ten cases (43%) were coronal and 12 cases were cervical (53%), and in one case (4%), the entry point was located 3 mm apical to the crestal bone.

Analysis of the chosen treatment approach revealed that all the cases with a narrow entry point (10 cases) were treated using a minimally invasive technique based on the internal approach to remove the resorptive tissue with obturation of the canal and the resorption area. Two of the 13 cases (15%) with a wide entry point were extracted, while the chosen treatment approach for the other 11 cases with a wide entry point was variable, as described in Table 2.

Discussion

Literature review revealed several publications that described different treatment approaches for advanced ICR lesions [11–15, 18–20]. The variety of treatment approaches for treating advanced ICR lesions illustrates the fact that recom-mendations for choosing the appropriate treatment approach for advanced ICR lesions have never been published.

The purposes of this study were to describe and discuss different treatment approaches for advanced invasive cervical resorption based on cone-beam computed tomography evalu-ation based on our experience in our endodontic department with the goal of facilitating decision making in those cases.

The existing classification of ICR was created in 1999 by the evaluation of two-dimensional periapical radiographs [1]. CBCT has proven to be crucial in confirming ICR diagnoses and in choosing the most appropriate and effective treatment approach to remove the resorptive tissue [6, 22–24]. The pres-ent study focuses on the important factors from CBCT evalu-ation (dimension and location of entry point) and recommends different treatment approaches based on these factors.

The important information that CBCT can provide includes the dimension, the coronal-cervical location, and the circumferential location of the entry point of the resorption into the tooth.

Based on our experience, the most important factor is the dimension of the entry point. Narrow entry point was defined as a diameter of the entry point of the resorption tissue into the root of less than 1 mm, while a wide entry point was defined as a diameter of the entry point of the resorption tissue into the root of more than 1 mm in diam-eter. In the present study, ten cases (43%) had a narrow entry point, while 13 cases (57%) had a wide entry point. All cases with narrow entry points were treated with a minimally invasive approach (Fig. 2). In this treatment approach, the crucial step of removing the resorptive tissue was based on the dissolution effects of sodium hypochlo-rite and calcium hydroxide [25]. This treatment approach enables the removal of resorption tissue along the root, even in the middle and apical third. Later, a combination technique for obturation was used. This method includes the lateral compaction in the apical part of the root canal and a warm component in the coronal and middle part of the root canal. This method is currently best for obturating the irregular form of a canal with resorptive areas [26]. In wide entry point cases, the ability to remove all the re-sorptive tissue during an internal approach decreases, and the risk for procedural mistakes during irrigation or ob-turation, such as overfilling of obturation materials, can be increased. Therefore, a surgical approach must be con-sidered as the main treatment, and extraction should be chosen in nontreatable cases. A surgical approach may be considered with or without orthodontic treatment. In some cases, the pulp status may necessitate endodontic treatment (Fig. 3).

Fig. 2 Adopted from previous study [21]. Maxillary left incisor. a Preoperative periapical radiograph. b CBCT cross-sectional view. c CBCT sagital views—narrow, palatal, and apical entry points. d Postoperative radiograph. e 48 months follow-up

Information that can determine whether a case is treatable or not include the circumferential location and the coronal-cervical location of the entry point.

Circumferentially, with a buccal or lingual location of the entry point, a surgical approach may be accepted as opposed to a proximal location. This surgery may be complicated, es-pecially in the molar area.

Fig. 3 Maxillary left incisor. a Preoperative periapical radiograph. b CBCT coronal views—wide, distal, and cervical entry points. c Postoperative radiograph. d 36 months follow-up

In the present study, in 16 cases (70%), the entry point was on the proximal side (mesial or distal side), and in seven cases (30%), it was on the lingual or buccal side. Of all 13 cases with a wide entry point, only three cases had a lingual or buccal entry point.

In cases with the coronal location of the entry of point (1.5 mm or more above the crestal bone), class 2 cavity treatment or a surgical approach may be considered (Fig. 4). In cases with a cervical location of the entry point (less than 1.5 mm from the crestal bone), a surgical ap-proach will sacrifice too much bone and an orthodontic approach (forced eruption) may be considered to expose the resorptive tissue (Fig. 3). If the final crown-root ratio is less than 1:1, extraction is recommended [15].

In cases with a wide entry point that complicates a surgical approach (proximal location and cervical or apical location), an internal approach may be chosen before resorting to extrac-tion (Fig. 4).

In conclusion, this article describes different treatment approaches for advanced invasive cervical resorption based on cone-beam computed tomography evaluation. Clinicians are provided with crucial three-dimensional information that can influence decision making for the treatment of these lesions.

Fig. 4 Mandibulary left first molar. a Preoperative periapical radiograph. b CBCT coronal view—wide, cervical, and mesial entry points. c CBCT cross-sectional view. d Postoperative radiograph. e 48 months follow-up

Further case series and longer follow-up periods will surely be needed to confirm the different treatment approaches for advanced ICR discussed in this study.

Compliance with ethical standards

Conflict of interest The authors declare that they have no conflict of interest.

Ethical approval This article does not contain any studies with human participants or animals performed by any of the authors. The study was approved by the Ethics Committee of Medical Corps, IDF (IDF-1684). The study was performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments.

Informed consent The Ethics Committee approved Informed Consent dismissal.

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