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Year : 2021  |  Volume : 24  |  Issue : 2  |  Page : 153-157
An innovative technique to safely perform active cleaning in teeth with open apices: CAB technique

1 Department of Medicine and Surgery, University of Salerno, Salerno, Italy
2 Department of Clinical, Surgical, Diagnostic and Pediatric Sciences, Section of Dentistry, Endodontic Unit, University of Pavia, Pavia, Italy
3 Private Practice, Genova, Italy
4 Department of Endodontics, Faculty of Dentistry, University of Alexandria, Alexandria, Egypt

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Date of Submission21-Jan-2021
Date of Decision10-Feb-2021
Date of Acceptance22-Feb-2021
Date of Web Publication09-Oct-2021


The current study aims to evaluate in vitro the extrusion of NaOCl, using an artificial root canal with an open apex, using different canal irrigation protocols. For this study, a transparent artificial root canal was used. The apex was shaped to be oversized and irregular in form. After root canal mechanical shaping, the artificial cylindrical chamber, which was made below the large apical foramen, was filled with fuchsine-stained bovine pulp tissue. Afterward, irrigation protocols were carried out and compared regarding their safety with regards to irrigant extrusion. Subsequently, the examiner created two groups, Group A: internal heating associated with ultrasonic activation and Group B: internal heating associated with ultrasonic activation, using the CAB technique. In both the groups, 5.25% sodium hypochlorite solution was used as the irrigant. Regarding assessing the presence or absence of the extrusion, photographs at ×20 were taken and analyzed. For the statistical analysis, a t-test for paired samples was used. Extrusion of irrigant beyond the apex was present only in Group A. The main objective of endodontic treatment is the removal of damaged tissues and bacteria. For this reason, active cleaning is crucial in all endodontic treatment cases. Internal heating followed with ultrasonic activation while using the CAB technique was an effective and safe technique to ensure no irrigant extrusion beyond the open apex.

Keywords: Internal heating, irrigants, NaOCl, open apex, safety, ultrasonic activation

How to cite this article:
Iandolo A, Amato A, Pantaleo G, Dagna A, Ivaldi L, di Spirito F, Abdellatif D. An innovative technique to safely perform active cleaning in teeth with open apices: CAB technique. J Conserv Dent 2021;24:153-7

How to cite this URL:
Iandolo A, Amato A, Pantaleo G, Dagna A, Ivaldi L, di Spirito F, Abdellatif D. An innovative technique to safely perform active cleaning in teeth with open apices: CAB technique. J Conserv Dent [serial online] 2021 [cited 2023 Dec 9];24:153-7. Available from:

   Introduction Top

The endodontic treatment's long-term success depends significantly on adequate three-dimensional (3D) cleaning of the complex endodontic space alongside the root canal shaping. Following that, the complete obturation of the complex root canal system.[1],[2],[3],[4] Possibly, a significant percentage of root canal failures can be caused by the presence of residual pulp tissue. The endodontic space consists of areas that are easily accessible to hand and rotary files (main root canals). On the other hand (as confirmed by many clinical and histological studies), some parts can be difficult to access or even completely inaccessible. Those areas can be in the form of isthmuses, apical deltas, loops, lateral and accessory canals, and dentinal tubules.[5] Consequently, root canal mechanical shaping alone is incapable of reaching all areas of the root canal system, regardless of the technique utilized, leaving parts of the canal untreated. Therefore, it is essential to carry out the endodontic biochemical 3D cleaning for both accessible and inaccessible spaces; once cleaned, it can be filled and obturated with gutta-percha and sealer during the obturation phase.

Bacteria and their by-products are the major cause of infection in the pulp and the periapical tissue.[6] An untreated root canal or improperly cleaned, shaped, and obturated can lead to the development or the persistence of a periapical lesion.

In the case of teeth with wide or open apices, it is advisable that the shaping must be minimal. Moreover, irrigation cannot be done actively because there is a risk of irrigant extrusion beyond the apex.[7],[8],[9] One of the proposed safe irrigation techniques for teeth with immature or open apices is negative apical pressure. This technique may avoid extrusion of irrigants beyond the apex, but it is not as powerful as the other techniques in pushing the irrigants inside the lateral anatomies and dentinal tubules.

When treating teeth with immature apices associated with periapical lesions, the resistant biofilms can be formed in the main canal and deep inside the lateral anatomies and dentinal tubules.[10] For this reason, it is critical to use high-performance activation techniques for irrigants. Consequently, the collagen apical barrier (CAB) technique, has been developed. This technique permits irrigants' activation, in case of an open apex, without risking the extrusion.

Hence, it is used after sufficient and minimal mechanical shaping. The CAB technique consists of placing a small part of collagen beyond the apex in teeth with open apices.

The collagen must be wetted by saline solution and then pushed beyond the apex with a suitable hand plugger. Only then, the irrigant activation can be inducted safely and effectively.

After the completion of irrigant activation, the collagen can be left beyond the apex. Or it can be removed using a modified small suction tip (Surgitip-endo, Coltene, Swiss) after cutting the first millimeters to guarantee its suction.

There are several irrigant activation techniques, and the most commonly used methods are the subsonic, sonic, and ultrasonic activation and the preheating of the irrigant at 50°C. Recently, a new technique has been introduced, as an improved technique, to activate and maximize sodium hypochlorite characteristics (NaOCl). This technique is the controlled heating technique directly inside the root canal, followed by ultrasonic activation of the heated NaOCl.

Iandolo et al. showed how sodium hypochlorite preheated to 50°C, 60°C, and 70°C and inserted into the root canal stabilize at body temperature in few seconds. Iandolo et al. also showed that at the apical and middle thirds, the temperature never exceeds 40°C.[11] It is well proven that sodium hypochlorite at boiling temperature can break up the pulp tissue at a higher speed up to 210 times compared to the same irrigant at room temperature.[12]

Based on that, this recent irrigant activation technique, internal heating combined with ultrasonic activation, is an effective 3D cleaning technique that allows a deeper cleaning inside lateral anatomies and even inside the dentinal tubules.[13]

Furthermore, dentinal tubule penetration of NaOCl and root canal cleanliness were improved significantly by ultrasonic activation of intracanal-heated NaOCl.[14]

The current study aims to evaluate, in vitro, using an artificial root canal with an irregular and open apex the extrusion of NaOCl through different protocols of canal irrigation.

   Materials and Methods Top

An artificial root canal 17 mm in length was used for this research. It was shaped using a ProTaper F3 30, 09 tapers (Protaper Gold, Dentsply Maillefer, Swiss), beyond the apex, then from the external side of the apex, a hand file type K 0.80 was used to enlarge the foramen and to create an irregular area (major diameter 1.62 mm and smaller diameter 0.75 mm) [Figure 1].
Figure 1: Artificial root canal with large and irregular apex

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Afterward, two groups were created: Group A and Group B. For each group, twenty experiments were carried out with a total of forty experiments. The same artificial root canal was a standard in all the experiments.

In Group A, internal heating followed by ultrasonic activation was carried out without using the CAB technique.

In Group B, internal heating followed by ultrasonic activation was done with the CAB technique.

After shaping the root canal, the artificial cylindrical chamber (3.4 mm in diameter and 0.75 mm thick with a volume of 6.98 mm3) below the apical foramen was filled with fuchsine-stained bovine pulp tissue to simulate a periapical lesion and covered with a histological slide.[15]

For each experiment, the fuchsine-stained bovine pulp tissue was changed. The insertion of the fuchsine-stained bovine pulp tissue was done using a ×20 magnification to ensure precision.

Root canal irrigation protocols

For the two groups, room temperature 5.25% sodium hypochlorite solution (CanalPro, Coltene, Swiss) was used as the irrigant. The irrigant extrusion was calculated by evaluating the amount of fuchsine remaining in the artificial cylindrical chamber.

The duration of each test for all the twenty experiments was 10 min. The amount of irrigant for each test was 6 ccs.

The same operator performed all the trials.

For Group A (without CAB technique), the irrigant was initially delivered with a 30G, side-vented needle (CanalPro irrigation tips, Coltene, Swiss), 2 mm away from the apical foramen followed by internal heating and then ultrasonic activation. For the intracanal heating, a heat source (System-B, Kerr, USA) was set to 180°C. The heat carrier used was the tip X-Fine 30/04 reached 3 mm from the main canal's end. During this phase, up-and-down movements of about 2–3 mm with the X-Fine tip were made.

In each activation cycle, 8 s of internal heating was alternated with 30 s of ultrasonic activation (EndoUltra, Coltene, Swiss). During the activation cycle, the tip of the ultrasonic device tip was 3 mm from the main canal's end. After each activation cycle (heat and then ultrasound), a minute of pause was allowed, and then, NaOCl was refreshed. A total of five cycles was performed.

For Group B (CAB technique), the same protocol in Group A was used, but before each experiment, a small part of collagen (Spongostan, Ethicon, USA) soaked in saline solution was positioned beyond the apex using a plugger calibrated at 17 mm [Figure 2].
Figure 2: Collagen beyond the apex

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To ensure precision, the ten parts of collagen were cut under ×20 magnification. After each testing, the collagen was removed and a new piece was inserted.

For the forty experiments, the operator did photos of the artificial cylindrical chamber at ×20 before and after each irrigant activation cycle. The photos were taken using an operating microscope (Kaps Som 32, Germany). Through the color change, the captured photos demonstrated whether or not there was an extrusion of irrigant beyond the apex. The photos were taken from the same distance and with the same intensity of light. During taking each picture, the sample was fixed in the same position. All photos of Group A and Group B were analyzed to evaluate the presence or absence of irrigant extrusion beyond the apex.

t-test for paired samples was used to assess the differences between the test and control groups. The statistically significant difference was evaluated between the two groups.

Case report, root canal treatment of tooth number 2.1 with open apex was done using the CAB technique [Figure 3].
Figure 3: Endodontic treatment of tooth number 2.1 with an open apex. (a) Preoperative radiograph, (b) Insertion of collagen for CAB technique, (c) Postoperative radiograph showing obturation, (d) Follow-up at 1-year showing healing

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A 22-year-old male patient was presented at our clinic with pain associated with the anterior maxillary area. Upon radiographic examination, a periapical lesion was noticed associated with tooth number 2.1.

The tooth had an open apex caused by previous trauma.

The treatment of choice was root canal treatment using the CAB technique followed by MTA apical plug and obturation.

After tooth isolation with a rubber dam, the access cavity was performed. The shaping phase was minimally done using only a hand K-file 0.20. Afterward, a collagen barrier was inserted through the root canal beyond the apical foramen. Then, the 3D irrigation protocol was carried out using internal heating followed by ultrasonic activation, as previously explained. Using an endodontic aspirating tip with a 0.60 mm diameter tip ( Surgitip-endo, Coltene), the apical collagen barrier was removed. Then, an apical plug of MTA (Aureoseal, Ogna, Italy) was placed.

In the 1-year follow-up, healing is observed [Figure 3].

   Results Top

In-Group A, all the experiments caused extrusion of irrigant beyond the apex. In contrast, Group B showed no extrusion in any of the tests.

Apical extrusion

Only Group A was associated with extrusion of the irrigant beyond the apex. The CAB technique suggests that it was safe under the experimental conditions [Figure 4] and [Figure 5].
Figure 4: Group A showing color change resulted from irrigant extrusionirrigant extrusion

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Figure 5: Group B showing no color change resulted from no irrigant extrusionirrigant extrusion

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   Discussion Top

The current study aimed to compare irrigant activation protocols in open apices with and without the CAB technique using an artificial root canal.

Bacteria and their by-products are the major etiological causative factors of pulp and periapical infection. Modern literature shows how problematic it can be to completely remove all the pulp tissue and bacteria from the whole complex endodontic space.[3],[4]

Furthermore, to gain short- and long-term positive results, it is necessary to use techniques and imply technologies that increase the profundity of root canal cleaning.[16]

Subsequently, it is crucial to perform irrigant activation in all root canal treatment cases, above all in open apex cases.

In such a situation with an open apex, it is well known that the shaping must be kept minimal to avoid further weakening of the root. Another challenging aspect in treating such teeth is that irrigation cannot be carried out actively because of the risk of extrusion of irrigant beyond the apex.

However, a safe irrigation technique for teeth with immature/open apices can be the negative apical pressure, and this technique will not cause extrusion of irrigant beyond the apex. Despite this technique's safety, it lacks the force to push the irrigant inside the lateral anatomies and dentinal tubules.

The situation can be further complicated in teeth with immature or open apices associated with periapical lesions. The latter case can be accompanied by biofilms inside the main canal and inside the lateral anatomies and dentinal tubules. For this reason, it is essential to use high-performance activation techniques for irrigants. Consequently, the CAB technique, collagen apical barrier technique, has been developed, which allows the activation of irrigants in case of an open apex without the risk of extrusion beyond the apex.[17],[18],[19],[20]

The CAB technique explained in the current study appears to yield promising results.

Irrigant activation techniques are many and vary.[13],[14],[21] Nonetheless, an effective and well-tested 3D cleaning technique involves internal heating of sodium hypochlorite followed by ultrasonic activation. With the aid of the CAB technique, this powerful technique can be used safely even in cases of teeth with open apices.[2],[14],[22],[23],[24],[25],[26]

However, the results gained in this study should be confirmed by prospective clinical trials.

   Conclusions Top

Only the protocol of irrigant activation associated with the CAB technique was able to avoid apical extrusion. Without using the CAB technique, the irrigant extruded beyond the apex.

In the case of open apices, the CAB technique allows performing irrigant activation safely.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

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Correspondence Address:
Prof. Alfredo Iandolo
Department of Medicine and Surgery, University of Salerno, Salerno
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jcd.jcd_42_21

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]

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