Following removal of the previous filling material and chemomechanical preparation, the canal was medicated with calcium hydroxide paste (Farmadental, Buenos Aires, Argentina), and the access cavity was sealed with composite resin (Filtek Z250, 3M ESPE, St. Paul, MN, USA) (Figures 1A–C).

At the subsequent visit, MTA HP (Angelus, Londrina, Brazil) was mixed and placed to create a 4 mm apical plug, with slight extrusion visible on the radiograph. The middle and coronal thirds were restored using fiber posts and dual-cure composite (Core Rebilda DC, VOCO, Cuxhaven, Germany), followed by placement of a provisional acrylic crown (Figures 1D–E). A definitive ceramic crown was delivered two months later.

The tooth remained asymptomatic throughout the follow-up period. Radiographic control at 2 years and 4 months showed evidence of periradicular healing (Figure 1F), which was confirmed at the 8-year follow-up (Figure 1G). The clinical appearance at 8 years is shown in Figure 1H

Case 2

A 52-year-old female patient presented with a sinus tract associated with tooth 11, with no reported history of pain. Periapical radiography and CBCT revealed a wide, poorly obturated canal and a periapical lesion (Figures 2A–B). The apical portion of the root appeared truncated (Figure 2A), although the patient denied any history of apical surgery. This finding suggested ongoing apical root resorption.

Retreatment was initiated by ultrasonic removal of the intracanal post. Following removal of the previous filling and chemomechanical preparation (Figures 2C–D), calcium hydroxide was placed as an intracanal medicament. At the subsequent visit, a 4 mm apical plug was created using MTA HP (Angelus, Londrina, Brazil) (Figure 2E). The remaining canal space in the middle and coronal thirds was restored with fiber posts and dual-cure composite (Core Rebilda DC, VOCO, Cuxhaven, Germany), followed by placement of a provisional crown (Figure 2F). The definitive crown was delivered eight months later.

The tooth remained asymptomatic, and follow-up radiography at six years confirmed complete periradicular healing (Figure 2G).

Case 3 

A 25-year-old female patient presented with diffuse intraoral swelling of the upper lip and acute pain associated with tooth 21. A periapical radiograph (Figure 2H) and CBCT scan (Figure 2I) revealed a wide, previously obturated canal and a periapical lesion. The diagnosis was acute apical abscess.

Non-surgical retreatment was indicated and initiated by removing the fiber post using an ultrasonic insert (E2D, Helse Ultrasonic, Santa Rosa de Viterbo, Brazil) (Figure 2J). After removal of the previous root filling and chemomechanical preparation, a calcium hydroxide paste (Farmadental, Buenos Aires, Argentina) was placed as an intracanal medicament (Figure 2L). At the following visit, ProRoot MTA (Dentsply Maillefer, Ballaigues, Switzerland) was inserted to create a 5 mm apical plug (Figure 2M).

The middle and coronal thirds were restored with fiber posts and dual-cure composite (Core Rebilda DC, VOCO, Cuxhaven, Germany), followed by provisional crown placement (Figure 2N). A definitive crown was delivered a few weeks later.

At the six-month follow-up, the patient remained asymptomatic, and radiographic examination showed advanced periapical healing (Figure 2O). At the one-year follow-up, the periapical lesion had completely resolved (Figure 2P), and the patient reported no symptoms since completion of treatment.

Case 4 

A 16-year-old male patient presented with a chronic apical abscess and a sinus tract associated with tooth 12. Periapical radiography (Figure 3A) and CBCT (Figures 3B–C) revealed a wide root canal and a large periapical lesion.

Following chemomechanical preparation, calcium hydroxide paste was placed as an intracanal medicament. At a subsequent appointment, a 5 mm apical plug was created using MTA HP (Angelus, Londrina, Brazil) (Figure 3D). The middle and coronal thirds of the canal were filled with fiber posts and dual-cure composite (Core Rebilda DC, VOCO, Cuxhaven, Germany), and the coronal restoration was completed with composite resin P60 (3M ESPE, St. Paul, MN, USA) (Figure 3D).

The tooth remained asymptomatic throughout the follow-up period. Radiographs at 3 and 6 years showed progressive reduction of the periapical lesion (Figures 3E–F). A CBCT scan taken after 6 years revealed near-complete healing of the periapical tissues, with a slight widening of the periodontal ligament space on the palatal aspect (Figures 3G–I).

Cases 5 and 6

An 18-year-old male patient presented for retreatment of teeth 11 and 12. Tooth 11 exhibited symptoms of an acute apical abscess, including pain and localized intraoral swelling, while tooth 12 presented as a chronic apical abscess with a sinus tract (clinical appearance shown in Figure 3J). Periapical radiography (Figure 3L) and CBCT imaging (Figures 3M–R) revealed wide, poorly obturated canals with metallic posts and associated periapical lesions in both teeth.

Retreatment began with post removal using an E12 ultrasonic insert (Helse Ultrasonic, Santa Rosa de Viterbo, Brazil) under magnification. Chemomechanical preparation was performed using a Clearsonic insert (Helse Ultrasonic) and hand files (Figure 3S). After drying the canals, absorbable sponges (Spongostan, Johnson & Johnson Ethicon Inc., Somerville, USA) were placed at the apical level to act as a barrier and prevent material extrusion.

Five-millimeter apical plugs were then created using Bio-C Repair (Angelus, Londrina, Brazil) (Figure 3T). The middle and coronal thirds of the canals were filled with fiber posts and dual-cure composite resin (Core Rebilda DC, VOCO, Cuxhaven, Germany), and provisional crowns were placed. These were later replaced with definitive restorations (Figure 3U).

Both teeth remained asymptomatic following obturation. Radiographic follow-ups at 6 months and 1 year showed progressive healing of the periapical tissues. Tomographic images at 1 year revealed reduced periapical lesions—smaller in tooth 11 and larger in tooth 12 (Figures 3V–X).

Cases 7 and 8

An 18-year-old male patient presented for retreatment of teeth 11 and 21. Tooth 11 showed signs of chronic apical periodontitis, while tooth 21 was diagnosed with a chronic apical abscess accompanied by a sinus tract. Periapical radiography (Figure 4A) and CBCT imaging (Figures 4B–D) revealed short metallic posts, wide and poorly obturated canals, and periapical lesions in both teeth.

Metallic posts were removed using the E12 ultrasonic insert (Helse Ultrasonic, Santa Rosa de Viterbo, Brazil). Canal desobturation and shaping were performed using the Clearsonic tip (Helse Ultrasonic) in combination with hand files (Figure 4E). After drying the canals, absorbable sponges (Spongostan, Johnson & Johnson Ethicon Inc., Somerville, USA) were placed at the apical level to act as a barrier.

A 5 mm apical plug of Bio-C Repair (Angelus, Londrina, Brazil) was placed in each tooth (Figure 4F). The middle and coronal thirds were then restored with fiber posts (RTD, Saint-Egrève, France) and dual-cure resin (Rebilda DC, VOCO, Cuxhaven, Germany). The provisional crowns were readapted (Figure 4G).

Since the completion of root canal obturation, both teeth have remained asymptomatic. Radiographic follow-up at 7 months (Figure 4H) and 1 year (Figure 4I) showed healthy periapical tissues. These findings were confirmed by CBCT scans at 1 year (Figures 4J–M).

Cases 9 and 10

An 8-year-old female patient presented with a history of dental trauma. A chronic apical abscess with an associated sinus tract was observed in tooth 21 (Figure 5A). Sensitivity testing yielded negative results for tooth 21 and positive results for tooth 11. Periapical radiography (Figure 5B) and CBCT imaging (Figures 5C–D) revealed an incompletely formed root apex and a periapical lesion in tooth 21. With informed consent from the patient’s parents, apexification was performed for tooth 21, while tooth 11 was kept under observation.

Following chemo-mechanical preparation of tooth 21, a calcium hydroxide paste (Farmadental, Buenos Aires, Argentina) was placed as an intracanal medicament. At the next visit, an apical plug was created using Bio-C Repair (Angelus, Londrina, Brazil). The middle and coronal thirds were obturated with thermoplasticized gutta-percha (Fast Fill, Eighteeth, Korea), and the access cavity was restored with composite resin (Filtek Z350, 3M ESPE, St. Paul, MN, USA). The tooth remained asymptomatic after treatment (Figures 5E–I).

One month later, the patient returned with signs of chronic apical abscess in tooth 11, including a sinus tract. Sensitivity testing confirmed pulp necrosis, and the tooth was treated following the same protocol used for tooth 21 (Figures 5J–O).

At the 1-year follow-up, both teeth were asymptomatic, and radiographic examination showed healthy periapical tissues (Figure 5P).

Case 11

A 24-year-old male patient presented for endodontic treatment of tooth 26, which had a persistent sinus tract. The tooth had already been accessed prior to referral and arrived in an open condition. Radiographic examination revealed a large periapical lesion and a wide mesiobuccal (MB) canal in the middle and apical thirds, with notably thin dentinal walls (Figure 6A). The palatal (P) and distobuccal (DB) canals exhibited normal morphology and were treated with conventional root canal therapy.

Apexification of the MB canal was performed using calcium hydroxide paste (Farmadental, Buenos Aires, Argentina) as an intracanal medicament. Subsequently, a 5 mm apical plug was created using ProRoot MTA (Dentsply Maillefer, Ballaigues, Switzerland) (Figure 6B), and the remainder of the MB canal was fully obturated with MTA. A metal post was placed in the P canal, and the coronal restoration was completed using composite resin (Filtek P60, 3M ESPE, St. Paul, MN, USA).

Since obturation, the tooth has remained asymptomatic, with complete resolution of the sinus tract. Follow-up radiographs taken at 1 year and 11 months (Figure 6C), and at 3 years and 5 months (Figure 6D), confirmed sustained periapical healing and the health of surrounding tissues.

Case 12

A 24-year-old female patient was referred for endodontic treatment of tooth 12, which presented with a sinus tract. The tooth had already been accessed prior to referral and arrived in that condition. Radiographic examination revealed a wide root canal and a large periapical lesion (Figure 6E).

Following chemomechanical preparation, a calcium hydroxide paste (Farmadental, Buenos Aires, Argentina) was placed as an intracanal medicament. At the subsequent appointment, a 5 mm apical plug was created using MTA HP (Angelus, Londrina, Brazil). The middle and coronal thirds were then restored with a metal post (Exatec, Hahnenkratt, Germany) and dual-cure resin (Core Rebilda DC, VOCO, Cuxhaven, Germany) (Figure 6F). A provisional crown was placed and replaced by a definitive crown six months later.

Since obturation, the tooth has remained asymptomatic. Follow-up radiographs taken at various intervals demonstrated progressive healing and the maintenance of healthy periapical tissues (Figures 6G–J).

Case 13 and 14

A 7-year-old male presented for consultation following dental trauma. Initial emergency care included soft tissue suturing, after which the patient was referred for the management of an intrusive luxation of tooth 11 and an uncomplicated crown fracture of tooth 21, involving the incisal third. Both teeth showed incomplete root formation (Figures 7A–B).

At the first visit, tooth 21 was managed conservatively with the placement of calcium hydroxide (Dycal, Dentsply) over the exposed dentin and protected with a polycarbonate crown to maintain pulp vitality and support continued root development. Tooth 11 was left for passive eruption under observation.

At the one-month follow-up, spontaneous re-eruption of tooth 11 had not occurred, and tooth 21 no longer responded to pulp sensitivity testing. As a result, tooth 11 was referred for orthodontic repositioning. Three months later, endodontic treatment of tooth 21 was initiated. This included chemo-mechanical preparation, placement of calcium hydroxide paste, and temporary sealing with Vitremer (3M ESPE) (Figure 7C). After one month, the intracanal medicament was replenished.

Seven months after trauma, and following the orthodontic repositioning of tooth 11, inductive (apexification) treatment was started on both teeth (Figure 7D). Radiographic imaging revealed significant inflammatory root resorption in both teeth, prompting further reassessment and repeated intracanal calcium hydroxide applications.

Final root canal obturation for both teeth was completed at the 3-year mark using ProRoot MTA (Dentsply Maillefer, Ballaigues, Switzerland), followed by coronal sealing with composite resin (Figure 7E). At that point, radiographs showed partial apical closure in tooth 21 but incomplete healing in tooth 11 (Figure 7F).

At the 13-year follow-up, extraction of tooth 11 was indicated due to progressive external root resorption. The tooth was removed to allow for future implant placement (Figure 7G).

At 26 years of age, a long-term follow-up of tooth 21 revealed excellent periapical repair, cortical bone continuity, and full functional integrity. The patient has remained asymptomatic since the final root canal filling (Figure 7H).

DISCUSSION

Apexification remains a dependable treatment for necrotic teeth with open apices, offering predictability and proven success with materials like Ca(OH)2 and MTA. In the present cases, more recent materials were also used with satisfactory outcomes, such as MTA HP and Bio C Repair. The outcomes of all cases were favorable, with 13 out of 15 teeth achieving complete healing, two teeth showing signs of healing, and one failure.

Apexification provides a controlled apical barrier, effectively minimizing the risk of extrusion and procedural errors. Its simplicity is also a significant advantage. In contrast, REPs aim to restore tooth vitality through pulp tissue regeneration. However, these techniques require the induction of bleeding into the canal, which can be unpredictable and may lead to complications (Lee & Song 2022). Additionally, there is an intrinsic risk of extrusion, as over-instrumentation is often necessary to facilitate bleeding.  

Also, the successful regeneration of the pulp-dentin complex is not achieved following REPs, because histological examinations have uncovered the presence of cementum-like tissue and uninflamed fibrous connective tissue within the canal and not pulp exactly (Martin et al., 2013). Despite this, a systematic review revealed that both regenerative and apexification using MTA had equal success and survival rates in treating immature necrotic teeth. Both groups showed high survival rates in the short term, of 95% until 24 months of follow-up (Wikstrom et al., 2021). This may be attributed to the common use of Ca(OH)2 in both modalities (Galler et al., 2016).    

In line with the results of the present case series, findings from a retrospective cohort study analyzing 632 apexification cases reinforce the high survival rates observed with apexification (Burns et al., 2023). The study reports survival rates of 95% at 1 year, 93% at 2 years, and 86% at 5 years.

In the present study, Ca(OH)2 was used as an intracanal medication or apical barrier. By creating an alkaline environment, it promotes osteoblastic activity and enhances mineral deposition in the apical region. Additionally, Ca(OH)2 stimulates bone and periodontal repair by increasing enzyme activity and inducing the differentiation of periodontal ligament cells into cementoblasts, contributing to tissue regeneration and the prevention of resorption (Paula-Silva et al., 2010; Kim et al., 2018).

The choice of an appropriate filling material for necrotic teeth with an open apex is crucial for treatment success, particularly regarding the apical plug. Due to the wide canals and absence of an apical constriction, biocompatible materials such as MTA and other calcium-silicate-based materials, are often recommended (Torabinejad et al., 2018). A significant advantage of these materials is that their properties are not compromised by moisture; on the contrary, moisture enhances their biological properties (Tabrizizadeh et al., 2015; Ayatollahi et al., 2016). A clinical study reported a success rate of 98% for immature incisors treated using the MTA plug in conjunction with adhesive materials (Ree & Schwartz 2017).

The root reinforcement and crown restoration also influence the treatment outcome of teeth with an open apex (Santos et al., 2022). The selected materials must account for the fragility of the thin dentinal walls, ensuring minimal stress on tooth structure while providing sufficient strength for long-term restoration.

A limitation of this study is the follow-up period of 1–2 years in some cases. Although 1 year is the minimum observation period, favorable outcomes may reverse if infection or reinfection occurs (European Society of Endodontology 2006). While the majority of healing typically occurs within the first year (Orstavik 1996), apexification failures are most likely to happen within the first three years (Burns et al., 2023), emphasizing the importance of regular monitoring during this critical time.

In conclusion, the simplicity and reliability of apexification in cases with open apices, especially those requiring intracanal posts, including in retreatments. The results reinforce apexification as a predictable and effective treatment option, with a high likelihood of long-term survival, particularly when supported by a permanent coronal restoration and regular monitoring.