Evaluation of the effects of different irrigation activation techniques on the surface roughness of dentin and blood clot in regenerative endodontic models.

Growth factors embedded in the extracellular matrix of the dentin play an important role in the migration, proliferation, and differentiation of dental pulp stem cells in regenerative endodontics. In regenerative endodontic treatments, the type of irrigation solution used is crucial for the release of growth factors (GFs) from the dentin matrix. This study evaluated the effectiveness of different irrigant activation techniques (IAT) using two different chelating agents, 17% ethylenediaminetetraacetic acid (EDTA) and 9% etidronic acid (HEDP), in terms of their GF release. Seventy-two mandibular premolar teeth were prepared to simulate an open apex. The root fragments were irrigated with 20ml of 1.5% sodium hypochlorite and 20ml of saline solution. Eight root fragments were randomly separated for the control group, and the remaining 64 fragments were randomly separated into eight groups based on two different chelating agents (17% EDTA and 9% HEDP) and four different IAT ((conventional needle irrigation (CNI), passive ultrasonic irrigation (PUI), sonic activation with EDDY, and XP-endo Finisher (XPF)). TGF-β1, VEGF-A, BMP-7 and IGF-1 release levels were determined using an ELISA, and statistical analysis was performed using the Kolmogorov-Smirnov test, ANOVA, and the Tukey test (p < .05). Compared to the control group, the experimental groups showed significantly higher GF release when using EDTA or HEDP. Among the activation groups, the EDDY group triggered the highest GF release, and the CNI group triggered the lowest. IAT with EDTA and HEDP can increase GF release, with EDDY being the most effective IAT method. Using chelating agents with IAT may be beneficial in regenerative endodontic treatments.

This study evaluated the effects of three chelating agents-glycolic acid (GA), ethylenediaminetetraacetic acid (EDTA), and etidronic acid (HEDP)-combined with different irrigation activation techniques on the pushout bond strength of Biodentine to root dentin after calcium hydroxide removal. A total of 120 extracted single-rooted mandibular premolars were randomly assigned to nine experimental and one control group (n = 12). Following Ca(OH)2 dressing and incubation, canals were irrigated with GA, EDTA, or HEDP, each activated using passive ultrasonic irrigation (PUI), XP-Endo Finisher (XPF), or conventional needle irrigation (CNI). Biodentine was placed into 2 mm-thick root slices, and pushout bond strength was measured using a universal testing machine. Statistical analysis was performed using one-way ANOVA for group comparisons, and two-way ANOVA was used to evaluate factor effects (α = 0.05). Overall, GA produced higher bond strength than EDTA (p = 0.027). The difference between GA and HEDP was not significant under PUI activation; however, GA yielded significantly higher bond strength than HEDP when activated with CNI or XPF. Using 10% GA with PUI enhanced Biodentine-dentin adhesion, suggesting its potential as a biocompatible and effective alternative to conventional chelators in regenerative endodontic treatments, improving coronal sealing and long-term stability.

Background and Aim:This study aimed to assess the effectiveness of different irrigant activation techniques in dissolving pulp tissue in the chamber of mandibular molars with Truss endodontic access, using a novel in vitro tooth model.Materials and Methods:Twenty-four freshly extracted human mandibular molars were selected, sectioned longitudinally, and standardized volume of bovine pulp tissue was placed into the pulp chamber. The split halves were then reassembled, sealed, and subjected to biomechanical preparation. The samples were randomly assigned to three groups based on the irrigation technique used: Conventional needle irrigation (CNI), modified endovac irrigation (MEV), and passive ultrasonic irrigation (PUI). Tissue dissolution was evaluated using stereomicroscopic imaging at ×10–×22 magnification. Statistical analysis was done using one-way ANOVA and post hoc tests.Results:The PUI group exhibited the highest mean percentage of bovine pulp tissue dissolved, followed by the CNI and MEV groups. However, the differences among the three groups were not statistically significant (P > 0.05). None of the techniques was able to achieve complete dissolution of the pulp tissue.Conclusion:All three irrigant activation techniques, CNI, MEV, and PUI, were similar in terms of bovine pulp tissue dissolution while using the truss access preparation in the new in vitro tooth model.

Aiming to kill bacteria in dentin tubules of infected dental pulp cavities, we evaluated the effects of sodium hypochlorite (NaOCl) solution agitated by different irrigation protocols, i.e., conventional needle irrigation (CNI), passive ultrasonic irrigation (PUI), the EDDY tip, and the neodymium-doped yttrium aluminum perovskite (Nd:YAP) laser. The EDDY achieved good antibacterial effects as passive ultrasonic irrigation in the coronal and middle thirds. Nd:YAP laser irradiation and PUI were effective in the apical third of the root canal. To evaluate the ability of NaOCl agitated by high-frequency sonic irrigation-EDDY, PUI, and Nd:YAP laser-to kill bacteria in infected root canal walls and if the associated temperature increases at the root surface during application. Infected root canal models were established, and roots were randomly divided into six groups: negative control, positive control, CNI, PUI, sonic agitation with EDDY, and Nd:YAP laser groups. After irrigation, the teeth were split and stained using the LIVE/DEAD BacLight Bacterial Viability Kit. Dead bacteria depth was evaluated by a confocal laser scanning microscopy and the temperature at the root surface was assessed using a thermal imaging camera during the irrigation process. In the coronal and middle thirds of the root canal, PUI and EDDY had stronger antibacterial effects than CNI (p<0.05); in the apical third, the antibacterial effects of PUI and Nd:YAP laser-activated irrigation were better than CNI (p<0.05). The maximum change in temperature was significantly greater during continuous Nd:YAP laser application compared with the other methods, but intermittent irrigation helped lessening this trend. NaOCl agitated by EDDY tip and PUI exhibited a similar bacteria elimination effect in the coronal and middle root canal. Nd:YAP laser was effective in the apical third and intermittent irrigation reduced its thermal impact.

BackgroundMultispecies biofilms located in the anatomical intricacies of the root canal system remain the greatest challenge in root canal disinfection. The efficacy of Er:YAG laser-activated irrigation techniques for treating multispecies biofilms in these hard-to-reach areas has not been proved. The objective of this laboratory study was to evaluate the effectiveness of two Er:YAG laser-activated irrigation techniques, namely, photon-induced photoacoustic streaming (PIPS) and shock wave-enhanced emission photoacoustic streaming (SWEEPS), in treating multispecies biofilms within apical artificial grooves and dentinal tubules, in comparison with conventional needle irrigation (CNI), passive ultrasonic irrigation (PUI), and sonic-powered irrigation (EDDY). Two types of multispecies root canal biofilm models were established in combination with two assessment methods using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) with the aim to obtain more meaningful results.MethodsNinety extracted human single-rooted premolars were chosen for two multispecies biofilm models. Each tooth was longitudinally split into two halves. In the first model, a deep narrow groove was created in the apical segment of the canal wall. After cultivating a mixed bacterial biofilm for 4 weeks, the split halves were reassembled and subjected to five irrigation techniques: CNI, PUI, EDD, PIPS, and SWEEPS. The residual biofilms inside and outside the groove in Model 1 were analyzed using SEM. For Model 2, the specimens were split longitudinally once more to evaluate the percentage of killed bacteria in the dentinal tubules across different canal sections (apical, middle, and coronal thirds) using CLSM. One-way analysis of variance and post hoc multiple comparisons were used to assess the antibiofilm efficacy of the 5 irrigation techniques.ResultsRobust biofilm growth was observed in all negative controls after 4 weeks. In Model 1, within each group, significantly fewer bacteria remained outside the groove than inside the groove (P < 0.05). SWEEPS, PIPS and EDDY had significantly greater biofilm removal efficacy than CNI and PUI, both from the outside and inside the groove (P < 0.05). Although SWEEPS was more effective than both PIPS and EDDY at removing biofilms inside the groove (P < 0.05), there were no significant differences among these methods outside the groove (P > 0.05). In Model 2, SWEEPS and EDDY exhibited superior bacterial killing efficacy within the dentinal tubules, followed by PIPS, PUI, and CNI (P < 0.05).ConclusionEr:YAG laser-activated irrigation techniques, along with EDDY, demonstrated significant antibiofilm efficacy in apical artificial grooves and dentinal tubules, areas that are typically challenging to access.

To establish whether irrigant activation techniques, namely manual dynamic activation (MDA), passive ultrasonic irrigation (PUI) and sonic irrigation (SI), improve the tubular penetration of sodium hypochlorite (NaOCl) into root dentine when compared with conventional needle irrigation (CNI). Secondly, investigate if increasing NaOCl concentration and/or contact time improves the performance of these techniques. A total of 83 extracted human maxillary permanent canines were decoronated to 15mm, and root canals prepared to a size 40, .10 taper. Root dentine was stained with crystal violet for 72h and embedded in silicone. Eighty specimens were randomly distributed into 16 groups (n=5) according to the irrigant activation technique, NaOCl concentration (2%; 5.25%) and irrigant contact time (10min; 20min). All activation techniques were used for 60s in the last minute of irrigation. Additionally, three teeth were not exposed to NaOCl to confirm adequate dentine staining had occurred (i.e. negative control). All specimens were subsequently dissected, observed under a light microscope and NaOCl penetration depth (µm) determined by measuring the average width of bleached dentine using ImageJ software. Statistical comparisons were made with paired and unpaired t-tests, anovas followed by post hoc Tukey's and Dunnett's tests, and a general linear model (α<0.05). Overall, NaOCl penetration ranged from 38.8 to 411.0µm with MDA, PUI and SI consistently resulting in significantly greater tubular infiltration than CNI (P<0.05). The deepest measurements in the coronal, middle and apical segments were all recorded in the MDA; 5.25%; 20min group and the least in the CNI; 2%; 10min group. Increasing either irrigant concentration or contact time resulted in significantly greater NaOCl penetration depths for all techniques and segments of the canal (P<0.05). However, when irrigant concentration and contact time were increased together, a significant interaction effect between these two independent variables was observed on overall NaOCl penetration (P<0.05). Agitating irrigants with MDA, PUI or SI, as well as using greater irrigant concentrations or contact times, potentiated NaOCl penetration into root dentine. However, longer durations of NaOCl exposure at lower concentrations resulted in similar depths of tubular penetration as those achieved at higher concentrations.

Measurement of eroded dentine tubule patency and roughness following novel dab-on or brushing abrasion

The study evaluated sealer penetration after calcium hydroxide (Ca(OH)2 ) removal from the root canals. Sixty single-rooted mandibular premolars were divided into six groups. Ca(OH)2 paste placed into the root canals except for the control group (CG) was removed using the following irrigation techniques: conventional needle irrigation (CNI), EndoActivator (EA), EndoVac (EV), passive ultrasonic irrigation (PUI) and photon-induced photoacoustic streaming (PIPS) technique. After canal filling, the penetration depth, penetration area and penetration percentage of the sealer were determined using confocal microscopy. The CG and EA had a greater penetration depth than CNI in the middle section. The CG exhibited a higher dentinal tubule penetration area than CNI, EV and PUI in the middle section. EA was significantly more effective than PUI in the coronal section for the percentage of sealer penetration. EA and PIPS removed Ca(OH)2 from root canals effectively because they presented similar penetration to the CG in all sections.

Introduction: Laser irradiation of dentin surface can affect its surface topography and roughness. Atomic force microscopy (AFM) is among the most efficient tools for determination of surface topography of natural biomolecules in nano-scales. Surface roughness affects plaque retention especially in the cervical region. This study aimed to assess and compare the obstruction of dentinal tubules and dentin surface roughness after irradiation of erbium: yttrium aluminum garnet (Er:YAG ) and CO2 lasers for treatment of dentin hypersensitivity (DH). Methods: Five disc-shaped samples measuring 3 mm in thickness were fabricated by horizontal sectioning of the cervical area of five extracted human molars using a low speed saw. Each disc was divided into 3 segments by a bur under water coolant. The three segments of each disc were placed on a glass slide. First segment: No intervention (control group). Second segment: Er:YAG laser irradiation (2940 nm, 50 mJ, 10 Hz and 0.5 W, 30 seconds) along with water coolant. Third segment: CO2 laser irradiation (10600 nm, 80 Hz, 0.3 W, 30 seconds) along with water coolant. After that, the surfaces underwent non-contact AFM. The diameters of dentinal tubules as well as surface roughness were then measured and statistically analyzed using repeated measures ANOVA. Results: The surface roughness parameters (Ra, Rq) showed increased roughness after laser irradiation and this increase in roughness after Er:YAG laser application was significant compared to the control group (P=0.048). However, CO2 laser caused no significant change in surface roughness. Also, after Er:YAG laser application, fewer open dentinal tubules were observed and the remaining open tubules had a smaller diameter. Conclusion: Based on the results, Er:YAG laser irradiation obstructs the dentinal tubules and increases the dentin surface roughness. This increase in surface roughness can cause microbial plaque retention and increase the risk of caries and periodontal disease. Application of CO2 laser (compared to Er:YAG) lead to slight but clinically significant obstruction of dentinal tubules and surface roughness.

ABSTRACTPreserving the natural dentition in its normal form and function is one of the major goals of endodontic treatment. Re-establishing the lost vitality and development of root maturation in immature permanent teeth with pulp necrosis/apical periodontitis is quiet challenging clinically. The very basis of regenerative endodontics relies on the concept of tissue engineering using stem cells, biomimetic scaffold, and bioactive growth factors to regenerate the pulp tissue damaged by microbial infection, injury, or developmental defects. In clinical endodontics, this approach is referred to as a “paradigm shift.” Even though repair instead of true regeneration is achieved with current protocols, it is hoped that further research in the area of stem-cell-based tissue engineering will allow for true regeneration and improved treatment outcomes. The aim of this review is to discuss about the various aspects of regenerative endodontics, current clinical protocols, and the future of pulp regeneration techniques.

Different final irrigation protocols on postoperative pain and swelling following single-visit non-surgical root canal treatment in necrotic mandibular first molars: a randomized controlled trial

ObjectiveThis article compares the effect of ultrasonic, sonic activation of intracanal heated 3% sodium hypochlorite and laser-activated 3% sodium hypochlorite (NaOCl) on root canal cleanliness using scanning electron microscope.Materials and MethodsEighty-eight permanent mandibular premolars were extracted and decoronated to obtain 14 mm of standardized root length. Working length was calculated and canals were prepared till size 25/0.04. Samples were randomly divided into four groups according to the method of irrigation employed (n = 22)—group A: passive ultrasonic irrigation (PUI) of 3% intracanal heated NaOCl, group B: sonic activation of 3% intracanal heated NaOCl, group C: activation of 3% NaOCl by diode laser, and group D: conventional needle irrigation (CNI). Samples were split into two halves and the presence of debris at these regions was graded under scanning electron microscope. The chi-square test was employed to assess significant differences in cleanliness scores and pairwise comparisons using the Dunn test were performed to identify specific group difference. Ap-value of < 0.05 was kept as level of significance for all analysis.ResultsGroup A and group B showed maximum cleanliness in middle third as compared with apical third. Group C (laser) showed better cleanliness in apical third as compared with middle third. While group D (CNI) irrigation showed the lowest cleaning efficiency both in the middle third and apical third.ConclusionIt was concluded that PUI with intracanal heating of 3% NaOCl and diode laser activation of 3% NaOCl can be recommended as a potential irrigant activation strategy to effectively clean inaccessible areas of the root canal system.

To establish whether irrigant activation techniques (IATs) result in greater intracanal smear layer and debris removal than conventional needle irrigation (CNI). Six electronic databases were searched to identify scanning electron microscopy studies evaluating smear layer and/or debris removal following the use of manual dynamic activation (MDA), passive ultrasonic irrigation (PUI), sonic irrigation (SI) or apical negative pressure (ANP) IATs in mature permanent teeth. Meta-analyses were performed for each canal segment (coronal, middle, apical and apical 1mm) in addition to subgroup analyses for individual IATs with respect to CNI. Outcomes were presented as standardized mean differences (SMD) alongside 95% confidence intervals (95% CI) and chi-squared analysis. From 252 citations, 16 studies were identified. The meta-analyses demonstrated significant improvements in coronal (SMD: 1.15, 95% CI: 0.72-1.57/SMD: 0.54, 95% CI: 0.29-0.80), middle (SMD: 1.30, 95% CI: 0.59-2.53/SMD: 0.8, 95% CI: 0.58-1.13) and apical thirds (SMD: 1.22, 95% CI: 0.83-1.62/SMD: 1.86, 95% CI: 0.76-2.96) for smear layer and debris removal, respectively. In the apical 1mm IATs improved cleanliness; however, differences were insignificant (SMD: 1.15, 95% CI: -0.47-2.77). Chi-squared analysis revealed heterogeneity scores of 79.3-92.8% and 0.0-93.5% for smear layer and debris removal, respectively. IATs improve intracanal cleanliness across a substantial portion of the canal, and therefore, their use is recommended throughout root canal preparation. However, current data is too heterogeneous to compare and identify superiority of an individual technique highlighting the need to standardize experimental protocols and develop a more representative research model to investigate the in vivo impact of IATs on clinical outcomes and periapical healing following root canal treatment.

&lt;p dir="ltr"&gt;&lt;b&gt;Introduction&lt;/b&gt;&lt;b&gt;:&lt;/b&gt; Presently, calcium hydroxide (CH) apexification and mineral trioxide aggregate (MTA) apexification are the available treatments for traumatized immature necrotic teeth. Although these treatments have been available for many years, few studies have assessed these techniques for long- term survival of teeth. Recently, a new treatment modality has emerged - regenerative endodontic treatment (RET). However, RET's clinical, radiographic, and disinfection protocols need to be evaluated.&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Aims&lt;/b&gt;&lt;b&gt;:&lt;/b&gt; This thesis investigates the clinical, radiographical, and microbiological outcomes of regenerative endodontic treatment. In addition, this thesis investigates the long-term survival of traumatized immature necrotic teeth after the use of apexification and identifies the risk factors for premature tooth loss.&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Materials and methods:&lt;/b&gt; This thesis includes a systematic literature review (Study I), an observational prospective cohort design (Study II), a randomized clinical trial (Study III), and a retrospective longitudinal observational cohort design (Study IV).&lt;/p&gt;&lt;p dir="ltr"&gt;In Study I, five scientific databases were screened (PubMed, Web of Science, Cochrane Library, Ovid/Medline, and Embase) for intervention studies on RET and/or apexification of traumatized immature necrotic teeth. Only peer- reviewed studies with a study size of at least 20 cases with a follow-up of 24 months were included. Eligibility assessment was blinded and performed independently. Subgroup analyses were performed on three outcomes: survival, success, and continued root development.&lt;/p&gt;&lt;p dir="ltr"&gt;In Study II, RET was performed on 75 traumatized necrotic immature incisors. The radiographic outcome measures were continued root formation (width and length), root resorption, apex closure, periapical index, and root development stage. The clinical outcome measures were percussion pain, palpation pain, pathological tooth mobility, swelling, sinus tract, ankylosis, crown discolouration, and subjective pain. Treatment outcomes were categorized as a success or failure based on the clinical and radiographic outcome measures.&lt;/p&gt;&lt;p dir="ltr"&gt;In Study III, microbiological assessment was based on root canal samples from 41 traumatized immature necrotic teeth treated with RET where two different root canal dressing were used in a randomized order (CH and CHD). Analysis of the average bacterial load (CFU/sample) and bacterial diversity (taxa/sample) was performed at three timepoints - before root canal dressing (S2); after debridement (S); and after root canal dressing (S5).&lt;/p&gt;&lt;p dir="ltr"&gt;In Study IV, records of 2400 children and adolescents were screened for presence of TDI to immature incisors where endodontic treatment with the two apexification techniques was performed between January 2003 and December 2022. These incisors were compared to a control group of mature teeth treated with conventional endodontic techniques. The following variables were studied: age, sex, apexification technique, presence of luxation and hard tissue injuries, preoperative root development stage (RDS), preoperative and postoperative periapical index (PAI), when tooth loss occurred, and overall survival time in years.&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Results:&lt;/b&gt; Seven studies with heterogenous designs were included in the final synthesis. The included articles in Study I revealed that both regenerative and apexification techniques had equal rates of success and survival and proved to be effective in the treatment of immature necrotic permanent teeth. Regenerative endodontic techniques appeared to be superior to apexification techniques in terms of stimulation of root maturation - i.e., root wall thickening and root lengthening.&lt;/p&gt;&lt;p dir="ltr"&gt;Study II revealed that RET was successful in 60% of the cases. When successful, RET presented meaningful outcomes, with a resolution of periapical infection, increased root length and width, and apex closure. Two predictive variables for continued root maturation were identified - preoperative root development stage and preoperative dentine wall thickness. The failed cases were related to lack of bleeding and persistent infections.&lt;/p&gt;&lt;p dir="ltr"&gt;Study III revealed that the primary microflora were more diverse in successful cases than in failed cases. Decreases in bacterial loads and diversity/sample occurred between S2 and S3, although new increases were seen at S5 in the CHD subgroup (successful and failed) and load/sample in the CH subgroup (failed). At S5, the successful cases showed more bacterial decreases. No specific species were associated with the outcomes with no statistical differences between the disinfection efficacies.&lt;/p&gt;&lt;p dir="ltr"&gt;Study IV showed that the median survival time was up to 10 years for CH apexification, 16.1 years for MTA apexification, 15.5 years for luxation injuries other than intrusions and avulsions, 12.5 years for intrusions, and 6.8 years for avulsions. The variables with significant negative impact on tooth survival were CH apexification, avulsion, and postoperative PAI of 3-5. No significant relationships were found for the variables MTA apexification, concussion, subluxation, lateral luxation, extrusion, intrusion, hard tissue injuries, preoperative RDS, preoperative PAI scores and postoperative PAI scores of 1-2. After adjustment, the risk for premature tooth loss was 13.5 times higher in CH apexification, approximately 2 to 4 times higher in PAI 3-5, and 5.6 times higher in avulsions.&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Conclusion:&lt;/b&gt; According to the published literature, both RET and apexification techniques have equal rates of success, survival, and effectiveness in the treatment of immature necrotic permanent teeth, although only RET stimulates root maturation. Knowledge gaps were identified regarding the treatment and follow-up protocols for both techniques. When successful, RET provides satisfactory clinical and radiographical outcomes. The failed cases were related to lack of bleeding and persistent infections, indicating that new techniques are needed to improve the predictability of RET. For microbiological outcomes, there were no statistical differences in CH and CHD efficacy. After root canal dressing (S5), microflora persisted in both successful and failed outcomes, but the abundance and diversity increased significantly only in the failed cases. Compared to the failed outcomes, the successful outcomes presented higher diversity and higher decreases of the primary microflora at S5. Only the failed cases had significant increases in abundance and diversity at S5. The analysis of the long-term outcomes identified CH apexification, avulsion, and postoperative PAI of 3-5 as prognostic variables with significant negative impact on the risk for premature tooth loss.&lt;/p&gt;&lt;h3&gt;List of scientific papers&lt;/h3&gt;&lt;p dir="ltr"&gt;I. What is the best long-term treatment modality for immature permanent teeth with pulp necrosis and apical periodontitis? &lt;b&gt;Wikström A,&lt;/b&gt; Brundin M, Lopes MF, El Sayed M, Tsilingaridis G. Eur Arch Paediatr Dent. 2021;22(3):311-340 &lt;a href="https://doi.org/10.1007/s40368-020-00575-1" rel="noreferrer" target="_blank"&gt;https://doi.org/10.1007/s40368-020-00575-1&lt;/a&gt;&lt;/p&gt;&lt;p dir="ltr"&gt;II. Endodontic pulp revitalization in traumatized necrotic immature permanent incisors: Early failures and long-term outcomes - A longitudinal cohort study. &lt;b&gt;Wikström A,&lt;/b&gt; Brundin M, Romani Vestman N, Rakhimova O, Tsilingaridis G. Int Endod J. 2022;55(6):630-645 &lt;a href="https://doi.org/10.1111/iej.13735" target="_blank"&gt;https://doi.org/10.1111/iej.13735&lt;/a&gt;&lt;/p&gt;&lt;p dir="ltr"&gt;III. Microbiological assessment of success and failure in pulp revitalization: A randomized clinical trial using calcium hydroxide and chlorhexidine gluconate in traumatized immature teeth. &lt;b&gt;Wikström A,&lt;/b&gt; Romani Vestman N, Rakhimova O, Gimeno DL, Tsilingaridis G, Brundin M. J Oral Microbiol. 2024 Apr 24;16(1):2343518 &lt;a href="https://doi.org/10.1080/20002297.2024.2343518" target="_blank"&gt;https://doi.org/10.1080/20002297.2024.2343518&lt;/a&gt;&lt;/p&gt;&lt;p dir="ltr"&gt;IV. Outcomes of apexification in immature traumatized necrotic teeth and risk factors for premature tooth loss: A 20-year longitudinal study. &lt;b&gt;Wikström A,&lt;/b&gt; Brundin M, Mohmud A, Andersson M, Tsilingaridis G. Dent Traumatol. 2024 Dec;40(6):658-671 &lt;a href="https://doi.org/10.1111/edt.12973" target="_blank"&gt;https://doi.org/10.1111/edt.12973&lt;/a&gt;&lt;/p&gt;

&lt;p dir="ltr"&gt;&lt;b&gt;Introduction&lt;/b&gt;&lt;b&gt;:&lt;/b&gt; Presently, calcium hydroxide (CH) apexification and mineral trioxide aggregate (MTA) apexification are the available treatments for traumatized immature necrotic teeth. Although these treatments have been available for many years, few studies have assessed these techniques for long- term survival of teeth. Recently, a new treatment modality has emerged - regenerative endodontic treatment (RET). However, RET's clinical, radiographic, and disinfection protocols need to be evaluated.&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Aims&lt;/b&gt;&lt;b&gt;:&lt;/b&gt; This thesis investigates the clinical, radiographical, and microbiological outcomes of regenerative endodontic treatment. In addition, this thesis investigates the long-term survival of traumatized immature necrotic teeth after the use of apexification and identifies the risk factors for premature tooth loss.&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Materials and methods:&lt;/b&gt; This thesis includes a systematic literature review (Study I), an observational prospective cohort design (Study II), a randomized clinical trial (Study III), and a retrospective longitudinal observational cohort design (Study IV).&lt;/p&gt;&lt;p dir="ltr"&gt;In Study I, five scientific databases were screened (PubMed, Web of Science, Cochrane Library, Ovid/Medline, and Embase) for intervention studies on RET and/or apexification of traumatized immature necrotic teeth. Only peer- reviewed studies with a study size of at least 20 cases with a follow-up of 24 months were included. Eligibility assessment was blinded and performed independently. Subgroup analyses were performed on three outcomes: survival, success, and continued root development.&lt;/p&gt;&lt;p dir="ltr"&gt;In Study II, RET was performed on 75 traumatized necrotic immature incisors. The radiographic outcome measures were continued root formation (width and length), root resorption, apex closure, periapical index, and root development stage. The clinical outcome measures were percussion pain, palpation pain, pathological tooth mobility, swelling, sinus tract, ankylosis, crown discolouration, and subjective pain. Treatment outcomes were categorized as a success or failure based on the clinical and radiographic outcome measures.&lt;/p&gt;&lt;p dir="ltr"&gt;In Study III, microbiological assessment was based on root canal samples from 41 traumatized immature necrotic teeth treated with RET where two different root canal dressing were used in a randomized order (CH and CHD). Analysis of the average bacterial load (CFU/sample) and bacterial diversity (taxa/sample) was performed at three timepoints - before root canal dressing (S2); after debridement (S); and after root canal dressing (S5).&lt;/p&gt;&lt;p dir="ltr"&gt;In Study IV, records of 2400 children and adolescents were screened for presence of TDI to immature incisors where endodontic treatment with the two apexification techniques was performed between January 2003 and December 2022. These incisors were compared to a control group of mature teeth treated with conventional endodontic techniques. The following variables were studied: age, sex, apexification technique, presence of luxation and hard tissue injuries, preoperative root development stage (RDS), preoperative and postoperative periapical index (PAI), when tooth loss occurred, and overall survival time in years.&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Results:&lt;/b&gt; Seven studies with heterogenous designs were included in the final synthesis. The included articles in Study I revealed that both regenerative and apexification techniques had equal rates of success and survival and proved to be effective in the treatment of immature necrotic permanent teeth. Regenerative endodontic techniques appeared to be superior to apexification techniques in terms of stimulation of root maturation - i.e., root wall thickening and root lengthening.&lt;/p&gt;&lt;p dir="ltr"&gt;Study II revealed that RET was successful in 60% of the cases. When successful, RET presented meaningful outcomes, with a resolution of periapical infection, increased root length and width, and apex closure. Two predictive variables for continued root maturation were identified - preoperative root development stage and preoperative dentine wall thickness. The failed cases were related to lack of bleeding and persistent infections.&lt;/p&gt;&lt;p dir="ltr"&gt;Study III revealed that the primary microflora were more diverse in successful cases than in failed cases. Decreases in bacterial loads and diversity/sample occurred between S2 and S3, although new increases were seen at S5 in the CHD subgroup (successful and failed) and load/sample in the CH subgroup (failed). At S5, the successful cases showed more bacterial decreases. No specific species were associated with the outcomes with no statistical differences between the disinfection efficacies.&lt;/p&gt;&lt;p dir="ltr"&gt;Study IV showed that the median survival time was up to 10 years for CH apexification, 16.1 years for MTA apexification, 15.5 years for luxation injuries other than intrusions and avulsions, 12.5 years for intrusions, and 6.8 years for avulsions. The variables with significant negative impact on tooth survival were CH apexification, avulsion, and postoperative PAI of 3-5. No significant relationships were found for the variables MTA apexification, concussion, subluxation, lateral luxation, extrusion, intrusion, hard tissue injuries, preoperative RDS, preoperative PAI scores and postoperative PAI scores of 1-2. After adjustment, the risk for premature tooth loss was 13.5 times higher in CH apexification, approximately 2 to 4 times higher in PAI 3-5, and 5.6 times higher in avulsions.&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Conclusion:&lt;/b&gt; According to the published literature, both RET and apexification techniques have equal rates of success, survival, and effectiveness in the treatment of immature necrotic permanent teeth, although only RET stimulates root maturation. Knowledge gaps were identified regarding the treatment and follow-up protocols for both techniques. When successful, RET provides satisfactory clinical and radiographical outcomes. The failed cases were related to lack of bleeding and persistent infections, indicating that new techniques are needed to improve the predictability of RET. For microbiological outcomes, there were no statistical differences in CH and CHD efficacy. After root canal dressing (S5), microflora persisted in both successful and failed outcomes, but the abundance and diversity increased significantly only in the failed cases. Compared to the failed outcomes, the successful outcomes presented higher diversity and higher decreases of the primary microflora at S5. Only the failed cases had significant increases in abundance and diversity at S5. The analysis of the long-term outcomes identified CH apexification, avulsion, and postoperative PAI of 3-5 as prognostic variables with significant negative impact on the risk for premature tooth loss.&lt;/p&gt;&lt;h3&gt;List of scientific papers&lt;/h3&gt;&lt;p dir="ltr"&gt;I. What is the best long-term treatment modality for immature permanent teeth with pulp necrosis and apical periodontitis? &lt;b&gt;Wikström A,&lt;/b&gt; Brundin M, Lopes MF, El Sayed M, Tsilingaridis G. Eur Arch Paediatr Dent. 2021;22(3):311-340 &lt;a href="https://doi.org/10.1007/s40368-020-00575-1" rel="noreferrer" target="_blank"&gt;https://doi.org/10.1007/s40368-020-00575-1&lt;/a&gt;&lt;/p&gt;&lt;p dir="ltr"&gt;II. Endodontic pulp revitalization in traumatized necrotic immature permanent incisors: Early failures and long-term outcomes - A longitudinal cohort study. &lt;b&gt;Wikström A,&lt;/b&gt; Brundin M, Romani Vestman N, Rakhimova O, Tsilingaridis G. Int Endod J. 2022;55(6):630-645 &lt;a href="https://doi.org/10.1111/iej.13735" target="_blank"&gt;https://doi.org/10.1111/iej.13735&lt;/a&gt;&lt;/p&gt;&lt;p dir="ltr"&gt;III. Microbiological assessment of success and failure in pulp revitalization: A randomized clinical trial using calcium hydroxide and chlorhexidine gluconate in traumatized immature teeth. &lt;b&gt;Wikström A,&lt;/b&gt; Romani Vestman N, Rakhimova O, Gimeno DL, Tsilingaridis G, Brundin M. J Oral Microbiol. 2024 Apr 24;16(1):2343518 &lt;a href="https://doi.org/10.1080/20002297.2024.2343518" target="_blank"&gt;https://doi.org/10.1080/20002297.2024.2343518&lt;/a&gt;&lt;/p&gt;&lt;p dir="ltr"&gt;IV. Outcomes of apexification in immature traumatized necrotic teeth and risk factors for premature tooth loss: A 20-year longitudinal study. &lt;b&gt;Wikström A,&lt;/b&gt; Brundin M, Mohmud A, Andersson M, Tsilingaridis G. Dent Traumatol. 2024 Dec;40(6):658-671 &lt;a href="https://doi.org/10.1111/edt.12973" target="_blank"&gt;https://doi.org/10.1111/edt.12973&lt;/a&gt;&lt;/p&gt;