Clinical and Radiographic Outcomes of Immature Teeth Treated with Different Treatment Protocols of Regenerative Endodontic Procedures: A Retrospective Cohort Study

Clinical, Radiographic, and Histologic Outcomes of Regenerative Endodontic Treatment in Human Immature Teeth Using Different Biological Scaffolds: A Systematic Review and Meta-analysis

BACKGROUND

Biological scaffolds such as blood clot (BC), platelet-rich plasma (PRP), platelet- rich fibrin (PRF), and platelet pellet (PP) are used in regenerative endodontic treatments (RETs).

OBJECTIVE

To systematically and quantitatively evaluate clinical, radiographic, and histologic outcomes of RET studies using different biological scaffolds.

METHODS

MEDLINE, Scopus, Cochrane library, and Embase were searched to identify studies on RET procedures with any scaffold type performed on immature non-vital human teeth, employing any type of biological scaffold. Clinical, radiographic, and histologic outcomes were extracted. Cochrane collaboration risk of bias tool and Newcastle-Ottawa scale were used for quality assessment. Random and fixed model meta-analysis was carried out with 95% confidence interval.

RESULTS

Thirty-two studies were included in the qualitative analysis from the primarily retrieved 1895 studies. Only one study had high risk of bias and 71.8% of the studies had high quality. None of the studies reported any histologic findings. Thirty studies were included in meta-analysis. Clinical success rate of RET using either BC, PRP, or PRF was >99%. Furthermore, 32%, 23%, and 27% of BC, PRP, and PRF cases regained vitality, respectively. Periapical healing was seen in 67%, 75%, and 100% of BC, PRP, and PRF cases, respectively. There was no statistical difference between BC, PRP, or PRF regarding clinical success or any radiographic outcomes.

CONCLUSION

There was no significant difference between BC, PRP, and PRF in terms of clinical and radiographic outcomes. When it is difficult or dangerous to induce bleeding in root canals, PRP and PRF may be employed instead.

Effect of Intracanal Scaffolds on the Success Outcomes of Regenerative Endodontic Therapy - A Systematic Review and Network Meta-analysis

INTRODUCTION

The scaffolds used in regenerative endodontic therapy (RET) provide structural support for cells so that they can adhere to the scaffolds and also are crucial for cellular proliferation and differentiation. The objective of this network meta-analysis was to compare effects of different intracanal scaffolds on success outcomes of RET.

METHODS

PubMed/Medline, EMBASE, Cochrane, CINAHL, Scopus, and Web of Science databases were searched. Studies evaluating and/or comparing clinical and/or radiographic success of RET using different scaffolds with a minimum of 12 months follow-up were included. The Cochrane Collaboration risk of bias (ROB) tool and appropriate tools from Joanna Briggs Institute were used for the assessment of ROB. A network meta-analysis was performed to compare the primary outcome (clinical success) and other success outcomes (root maturation, and pulpal sensibility) using different scaffolds.

RESULTS

Twenty-seven studies fulfilled the desired inclusion criteria of which 25 had a low ROB whereas 2 had a moderate ROB. Clinical success of RET using platelet-rich plasma (PRP), blood clot (BC), and platelet-rich fibrin (PRF) scaffolds ranged between 91.66%-100%, 84.61%-100%, and 77%-100% respectively. The different scaffolds did not show any statistically significant difference in clinical success (PRF vs BC [P = 1.000], PRP vs BC [P = 1.000], and PRF vs PRP [P = .999]), apical root closure (PRF vs BC [P = 1.000], PRP vs BC [P = .835], PRF vs PRP [P = .956]), and pulp sensibility (PRF vs BC [P = .980], PRP versus BC [P = .520], and PRF vs PRP [P = .990]).

CONCLUSION

The intracanal scaffolds used during RET did not result in significant differences in regard to clinical success, root maturation, and pulpal sensibility.

Tissue Characteristics in Endodontic Regeneration: A Systematic Review

The regenerative endodontic procedure (REP) represents a treatment option for immature necrotic teeth with a periapical lesion. Currently, this therapy has a wide field of pre-clinical and clinical applications, but no standardization exists regarding successful criteria. Thus, by analysis of animal and human studies, the aim of this systematic review was to highlight the main characteristics of the tissue generated by REP. A customized search of PubMed, EMBASE, Scopus, and Web of Science databases from January 2000 to January 2022 was conducted. Seventy-five human and forty-nine animal studies were selected. In humans, the evaluation criteria were clinical 2D and 3D radiographic examinations. Most of the studies identified a successful REP with an asymptomatic tooth, apical lesion healing, and increased root thickness and length. In animals, histological and radiological criteria were considered. Newly formed tissues in the canals were fibrous, cementum, or bone-like tissues along the dentine walls depending on the area of the root. REP assured tooth development and viability. However, further studies are needed to identify procedures to successfully reproduce the physiological structure and function of the dentin–pulp complex.

10-Year Follow-up of Previously-Traumatized Immature Permanent Incisors Sustaining Second and Third Traumatic Injuries After Revascularization Treatment: Case reports

The long-term prognosis of previously traumatized immature permanent teeth treated with guided endodontic repair is well documented, but little is known about how these teeth respond to further traumatic injury after treatment. This case report presents the 10-year clinical and radiographic findings of two patients with traumatized maxillary incisors who underwent guided endodontic repair treatment and sustained two further traumatic injuries. Three crown-fractured maxillary central incisors with pulp necrosis were treated with a protocol that used 2.5% NaOCl irrigation, 3-4 week medication with calcium hydroxide or ciprofloxacin-metronidazole paste, induction of apical bleeding, and coronal sealing with mineral trioxide aggregate. One tooth sustained subluxation and a crown fracture after 20 months and 7 years, respectively. Two other teeth had a luxation injury at 9 months and subluxation 6.5 years after the regenerative treatment. One subluxated and one luxated tooth remained free of symptoms for 10 years with radiographic evidence of progressive root canal calcification, while the other luxated incisor required root canal treatment after 7.5 years. Although teeth treated with the so-called "regenerative" endodontic techniques do not possess true pulp tissue, the reparative tissue may respond to traumatic injuries in a similar manner to teeth with normal pulps.

Periodontal Ligament Cells Are Involved in the Formation of Intracanal Cementum-Like Tissue After Regenerative Endodontic Procedures: A Mouse in situ Model

Regenerative endodontic cell-homing procedures are frequently performed on injured immature teeth diagnosed with pulp necrosis and/or apical periodontitis. The representative histological finding after those procedures is cementum-like tissues filling in the root canal but details of the healing process remain unknown. We investigated that healing process histologically using a mouse in situ model. Regenerative endodontic procedures were experimentally performed on noninfected maxillary first molars of 6-week-old male C57BL/6 mice, after which the healing process was investigated using histology and immunohistochemistry. Immediately after the regenerative endodontic cell-homing procedures, blood clots were seen in the root canals that disappeared over time. On day 7, the blot clot in the root canal was replaced by granulation tissue. From day 14 onward, cementum-like tissues were filled in the root canals, while the amount of fibrous tissue was reduced. Immunohistochemically, positive reactions for periostin were seen in the fibrous tissue in the root canal, the apex, and periodontal ligament cells. On the other hand, positive reactions for nestin were not detected in the root canal. CD31-positive cells with a luminal structure were also observed in the fibrous tissue around the apex and around the newly formed cementum-like tissues in the root canal. Thus, in this study, we have established an in situ mouse model of regenerative endodontic procedures. The results of this study suggest that periodontal ligament cells and vascular endothelial cells grow into the root canals from the apex, replace the blood clots, and participate in the formation of cementum-like tissues with angiogenesis during the healing process of regenerative endodontic procedures.

A critical analysis of clinical research methods to study regenerative endodontics

Regenerative endodontic treatment such as revitalization provides a treatment option for immature teeth with pulp necrosis. The main difference to the alternative procedure, the apical plug, is the induction of a blood clot inside the canal as a scaffold for healing and new tissue formation. Due to the biology-based and minimally-invasive nature of the treatment, revitalization has raised considerable interest in recent years. Whereas the procedure is fairly new and recommendations from endodontic societies have been in place only for a few years, the treatment protocol has evolved over the past two decades. Evidence has been created, not only from laboratory and animal work, but also from clinical studies including case reports, cohort studies and eventually prospective randomized controlled clinical trials, systematic reviews and meta-analyses. However, the research methods and clinical studies with subsequent reports oftentimes present with methodical limitations, which makes it difficult to objectively assess the value of this treatment modality. Several open questions remain, including the need for a more differentiated indication of revitalization after different traumatic injuries, the long-term prognosis of treated teeth and the true benefits for the patient. Therefore, this review aims to identify and reflect on such limitations, scrutinizing study design, diagnostic tools, procedural details and outcome parameters. A core outcome set is also proposed in this context, which can be considered in future clinical investigations. These considerations may lead to a more detailed and stringent planning and execution of future studies in order to create high-quality evidence for the treatment modality of revitalization and thus provide more robust data, create a larger body of knowledge for clinicians and further specify current recommendations.