Background/Objectives: To assess the cytocompatibility, antibacterial and anti-biofilm efficacy of grape seed extract (GSE) and quercetin hydrogels versus calcium hydroxide (CH) as intracanal medications (ICMs) against an endodontic ex vivo biofilm model. Methods: Single-rooted teeth (n = 50) were prepared and sterilized before being infected with E. faecalis to develop a mature biofilm. They were divided into five equal groups according to the ICM used: G1: medicated with CH paste, G2: medicated with GSE hydrogel, G3: medicated with quercetin hydrogel, G4: positive control group that was infected and not medicated, and G5: negative control group that was neither infected nor medicated. After 1 week, the ICM was removed, and the root canals were cultured to assess the antibacterial efficacy by counting the colony-forming units and the anti-biofilm efficacy by the crystal violet assay. Dead/live bacterial viability was assessed by CFLSM examination, while the cytocompatibility was assessed using the MTT assay. Results: CH had the best antibacterial efficacy, followed by GSE and quercetin hydrogels (p < 0.001). Regarding the anti-biofilm efficacy, GSE was superior, followed by quercetin and CH (p < 0.001). CFLSM examination showed CH and GSE hydrogel to be highly effective in comparison to the positive control (p < 0.0001), with no statistical difference between them (p > 0.05). CH showed significantly higher cell viability percentages using a 500 μg/mL, while quercetin and GSE started to show cell viability > 70% at concentrations of 125 μg/mL and 62.5 μg/mL. Conclusions: CH fulfilled the ideal requirements of ICM as being both antibacterial and non-cytotoxic compared to the other materials tested.

Introduction: This study aimed to evaluate the removal of a bio film-mimicking hydrogel from isthmus structures in a simulated complex root canal system consisting of 2 curved root canals by Laser-activated irrigation (LAI, AdvErl Evo, Morita) and mechanical activation techniques. Methods: A 3D-printed root canal model with 2 parallel root canals (60 degrees - curvature, radius 5 mm, dimension 25/.06) with a total length of 20 mm connected via isthmuses (2.5 ! 0.4 ! 0.2 mm) at 5 mm and 8 mm from the apical endpoint and with lateral canals (diameter 0.2 mm) in all directions at 2, 5, and 8 mm from the apex was filled with a colored bio film-mimicking hydrogel. Irrigation protocols under continuous irrigation with distilled water (3 ! 20s per root canal; 3 ml/20s; n = 20) included conventional needle irrigation ( = NI); manual agitation ( = MA, gutta-percha point 25/.06); EndoActivator ( = SAI-EA, 25/.04); EDDY ( = SAI-E, 25/.04); ultrasonically-activated irrigation ( = UAI) and LAI (Er:YAGlaser; P400FL tip at canal entrance; 25pps, 50 mJ, 300 ms). Removal of the hydrogel was determined as a percentage via standardized photos through a microscope. Statistical analysis was performed using Kruskal -Wallis and Conover tests ( P = .05). Results: Laseractivated irrigation (LAI) was associated with the greatest removal of hydrogel from the entire root canal system ( P < .05), followed by SAI-E. No signi ficant differences were reported for the coronal isthmus between LAI, SAI-E, NI, and MA ( P > .05), but inferior results for SAI-EA and UAI ( P < .05). In the apical isthmus, all techniques outperformed UAI ( P < .05), with LAI, SAI-E, and NI showing the best results ( P < .05). Conclusions: Laser-activated irrigation (LAI) was superior to other irrigation techniques in the entire root canal system. SAI-E and NI performed comparable to LAI in the isthmuses.

Reciprocating motion expands the lifetime of endodontic instruments during the preparation of severely curved root canals. This study aimed to investigate the time to fracture (TTF) and number of cycles to failure (NCF) of different reciprocating instruments (n = 20 in each group) at body temperature using a dynamic testing model (amplitude = 3 mm). Reciproc Blue (RPB), size 25/.08, WaveOne Gold (WOG) 25/.07, Procodile (Proc) 25/.06, R-Motion (RM_06) 25/.06 and R-Motion (RM_04) 30/.04 instruments were tested in their specific reciprocating motion in artificial matching root canals (size of the instrument ± 0.02 mm; angle of curvature 60°, radius 5.0 mm, and centre of curvature 5.0 mm from apical endpoint). The number of fractured instruments, TTF, NCF, the and lengths of the fractured instruments were recorded and statistically analysed using the Chi-Square or Kruskal–Wallis test. Both TTF (median 720, 643, 562, 406, 254 s) and the NCF (3600, 3215, 2810, 2032, 1482 cycles) decreased in the following order RM_06 > RPB > RM_04 > Proc > WOG with partially significant differences. During testing, only six RM_06 instruments fractured, whereas 16/20 (RPB), 18/20 (Proc), and 20/20 (RM_04, WOG) fractures were recorded (p < 0.05). Within the limitations of the present study, blue-coloured RPB and RM instruments exhibited a significantly superior cyclic fatigue resistance compared to SE-NiTi and Gold-wire instruments. Heat treatment, cross-sectional design and core mass significantly influenced the longevity of reciprocating instruments in cyclic dynamic testing.

AIM:To investigate the influence of pulse energy, tip geometry and tip position in simulated 3D-printed root canals with multiple side canals at different levels in all directions on the cleaning performance of laser-activated irrigation (LAI) compared to sonic activation (EDDY) and conventional needle irrigation (NI). METHODOLOGY:3D-printed root canal models (25/.06, length 20 mm, curvature 60°, radius 5 mm) with side canals (diameter 0.2 mm) at 2, 5 and 8 mm from the apex were filled with coloured biofilm-mimicking hydrogel. LAI (Morita AdvErL Evo, Kyoto, Japan) was performed with six settings (n = 20; pulse-energy, pulses per second [PPS], tip position): LAI1 (50 mJ, 25 PPS, P400FL, canal entrance [CE]), LAI2 (same as LAI1, but insertion depth 9 mm before the apical endpoint [AE] [corresponding to 1 mm above the first lateral canals]), LAI3 (80 mJ, 25 PPS, P400FL, 9 mm before AE), LAI4 (same as LAI 3, but at CE) for 3 × 20 s each, LAI5 (50 mJ, 25 PPS, P400FL 2 × 20 s, CE & R200T (30 mJ, 25 PPS, 1 × 20 s, 9 mm before AE), LAI6 (30 mJ, 25 PPS, R200T, 9 mm before AE, 3 × 20 s). A continuous irrigation (3 mL/20 s) using distilled water accompanied the irrigation cycles. NI and EDDY (3 × 20 s each; 3 mL/20 s irrigation, insertion AE minus 1 mm, amplitude 4 mm) served as control groups. Biofilm-mimicking hydrogel removal (ImageJ, NIH) was assessed for the entire system, the central canal and the lateral canals using standardized photographs with a microscope (Expert DN, Müller-Optronic) and statistically analysed was performed using Kruskal-Wallis and Dunn tests (p = .05). Irrigant extrusion beyond the foramina was also recorded. RESULTS:LAI2 (99.08%; interquartile range [IQR]: 96.85-100.00) and LAI3 (97.50%; 96.24-100.00) achieved the significantly best and LAI6 (80.08%; 73.41-84.69) the significantly worst removal of hydrogel from the entire root canal system amongst all LAI configurations (p < .05). There were no significant differences between LAI6, EDDY (72.89%; 67.49-76.22) and manual irrigation (54.39%; 51.01-56.94) (p > .05). R200T laser tip caused significantly more often irrigant extrusion than all other techniques (p < .05). CONCLUSION:Tip design, energy settings, and the positioning of the laser tip below the canal entrance caused an improvement in cleaning performance of the LAI. However, the small R200T tip created significantly more procedural errors (irrigant extrusion) due to higher concentrated energy.

This 2-part randomized parallel triple-blind clinical trial adopts a unique model assessing clinically-set hydraulic calcium silicate-based sealers (HCSBS) after different root canal dryness protocols and obturation techniques. For the first phase of the study, 24 teeth scheduled for orthodontic extractions were allocated into four groups according to the canal dryness protocol and the obturation technique. G1 (CLC-AHP): cold lateral compaction (CLC) with AH Plus sealer, G2 (CLC-ES-SD): CLC with Endosequence (ES) after standard canal(s) dryness (SD); G3 (SC-ES-SD): matching single-cone (SC) with ES after SD; G4 (SC-ES-PD): as G3 but after partial canal(s) dryness (PD). Teeth were extracted after one month of clinical service and examined for intracanal voids by micro-CT (2D 3D). For the 2nd phase, another 24 teeth were allocated into four groups according to the root canal dryness protocol and the HCSBS used (ES or CeraSeal (CeS)). Teeth were extracted after one month and sectioned vertically for energy dispersive X-ray (EDX)/scanning electron microscope (SEM) examination. One-way ANOVA with Games-Howell post-hoc test and Chi-square test with multiple z-tests were used for statistical analysis. SC-PD showed the highest percentage of voids (p < 0.05). MicroCT scans as well as EDX/SEM examination showed that PD resulted in significantly larger interfacial gaps (p < 0.001) with more hydration products at the sealer/dentin interface than SD. Both tested dryness protocols allowed the hydration of HCSBS and the formation of hydration products, thus standard dryness is recommended to reduce the incidence of intracanal voids. When using the single-cone obturation technique, intentional root canal moisture negatively affects the performance of HCSBS. http://www.clinicaltrials.gov, ID: NCT05808062.

Undergraduate students often lack experience in diagnosing dental pain, especially in those cases with pulpal involvement and a need for endodontic treatment. Not all university dental clinics provide participation of the students in providing emergency dental services. During their undergraduate dental education, the students have to be provided with clinical teaching and support how to diagnose and prepare treatment plans for emergency and/or elective dental treatment. Thus, after graduation young dentists would not face challenges in diagnosing the location and cause of the odontogenic pain. Developing an e-learning tool utilizing the Generative Pre-trained Transformer 4 (GPT-4) Model (OpenAI) is to enable students to undergo a proper training on how to diagnose diseases of endodontic origin in realistic conversational setting on virtual patients. Unlike previous linear conversational approaches,1 the GPT-4 model allows for advanced, life-like conversations. International Nursing Association for Clinical Simulation and Learning standards of best practice simulation design were applied.2 Students receive a briefing within the e-learning tool including an introduction to the setting, a program overview, and a guide for a structured diagnostic approach. Afterward, they will engage in diagnosing a virtual patient. Students are required to conduct the diagnostic process, fostering a profound immersion in the topic and thereby cultivating the development of a structured personal approach of diagnosing the cause of dental pain. They will have the opportunity to work simultaneously on their communicative skills. To achieve the necessary realism, each case provides a patient's history and all essential parameters required for a final diagnosis. These include pain history, medical history, clinical presentation, clinical tests, and radiographic findings (Figures 1 and 2). This proposed approach also presents the opportunity for students to learn how to educate their patients on their condition and the proposed treatment plan in order to obtain informed consent for dental treatment. This prompts the student to apply their theoretical knowledge in a reality-based setting and critically examine their own potential knowledge gaps (Figure 3). The completed conversation with the patient is followed by a debriefing, providing information on the correct diagnosis and an exemplary annotated chat protocol conducted by an experienced clinician. In this way, observational learning is facilitated and enhanced in relation to the students’ structured diagnostic and communication approach. The preliminary pilot testing with a selected group of students and teachers has yielded promising results, suggesting this method as a viable means of practicing diagnostic skills in a secure environment. However, the significant effort required to construct patient cases cannot be understated, particularly due to the difficulty in obtaining clinical images and radiographs because of copyright restrictions. Furthermore, careful planning and iterative refining were necessary to obtain reliable outputs from the artificial intelligence model. To mitigate the unwanted behavioral characteristics of GPT models, such as hallucinations, a detailed and comprehensive case design was needed, along with restrictive guidelines for the GPT model. Thus, the model was confined to answer only database-solvable queries and otherwise it would have responded only in an evasive manner. A future pilot study is planned with a more extensive group of undergraduate students to appraise the effectiveness of this program. The objective is to gather additional insights into how it is perceived by a larger student population, which will later help identify areas for further enhancements. The authors have nothing to report. Open access funding enabled and organized by Projekt DEAL. The authors declare they have no conflicts of interest.

The mandibular premolars can pose a significant challenge in root canal treatment due to their complex canal system. This study investigated the prevalence of multiple roots and complex canal morphology of mandibular premolars in a selected Egyptian sub-population using cone beam computed tomography (CBCT). 283 CBCT scans (131 males, 152 females, age 18–70) included 1132 mandibular premolars (566 first, and 566 second premolars) were viewed for incidences ofvariation in root numbers and canal configuration according to Vertucci’s classification. CBCT images were assessed by two endodontists, data were statistically analyzed using Fisher exact and Chi-square tests. The majority of first premolars (85.7%) exhibited a single root, whereas 14.7% had 2 roots with a significantly higher frequency in males (19.8%) than in females (9.5%) ( P < .05). The most prevalent type was type I (57.8%), followed by type V (21.7%), while types II and VII made up only 1%. Types V and III were more prevalent among females, while males had a higher prevalence of types I and IV. In 2.5% of cases, mandibular second premolars were found to have 2 roots, with a higher incidence in males ( P < .05). Type I canals were significantly more prevalent (90.8%) than other types, followed by type V (5.3%) ( P < .05). A statistically significant gender correlation was found regarding root number and canal configuration. It is not uncommon to find mandibular first premolars with two roots in the southern Egyptian population, particularly in males. These observations may be valuable for dentists who treat Southern Egyptians, in Egypt and other countries.

Address for correspondence: Edgar Schäfer ZMK-Klinik, Waldeyerstr.30, D-48149 Münster, Germany E-mail: eschaef@uni-muenster.de When the reader first glances through the book (1), he/she will be impressed by the volume (just over 800 pages), the excellent printing quality, the numerous high-quality colour figures, the paper quality and the invariably outstanding documentation of radiographs and clinical pictures of the clinical cases that have been included. The expectations raised are not disappointed on closer inspection of this book. The editors of great renown, Dr. Ahmed is currently the Deputy Editor-in-Chief of the European Endodontic Journal and Prof. Dummer is the former Editor-in-Chief of the International Endodontic Journal, succeeded in attracting proven experts as authors for each chapter – the list of contributors reads like a “who’s who” in endodontics!

Patients diagnosed with an autoimmune disease are often systemically medicated with glucocorticoids. Autoimmune pancreatitis (AIP) Type 1 is considered a rare autoimmune disease, which is very well responsive to glucocorticoids and hence can be treated optionally on a long-term basis using low dose of the drug. Apical lesions of root canal-treated teeth can be solved by retreatment of the preexisting root canal obturation or via surgical approaches. This case report relates to a 76-year-old male patient, whose symptomatic acute apical periodontitis was treated nonsurgically by root canal treatment. However, overtime both roots of tooth 46 were associated with asymptomatic apical lesions. Despite progression of the lesions, due to a painless situation, the patient refrained from proceeding with any further treatment options after explaining the pathological pathway with all its consequences. A few years later the patient was prescribed 2.5 mg glucocorticoid prednisone daily for long-term therapy due to an AIP Type 1. Six years later under strict glucocorticoid therapy the apical lesions healed nearly completely and the patient remained free of symptoms without any further interventions. These observations suggest that prospective clinical studies are required to further elucidate the potential healing effect of systemic long-term low-dose glucocorticoid medication on lesions of endodontic origin.

AimOrthograde retreatment after failed apicectomy maybe a treatment alternative to endodontic resurgery. The purpose of this study was to examine the clinical outcome of orthograde endodontic retreatment after failed apicectomy. MethodologySuccess was rated radiographically in 191 cases of orthograde retreatment after failed apicectomy that were treated in a private practice with a documented recall of at least 12 months. The radiographs were rated individually by two observers, in cases of disagreement a consensus was reached by joint discussion with a third observer. Success or failure were evaluated according to previously described criteria. The success rate and the median survival were calculated using the Kaplan-Meier survival analysis. The log rank test was used to evaluate the effect of prognostic factors/predictors. Hazard ratios of predictors were analysed using Univariate Cox Proportional Hazard regression analysis. ResultsThe mean follow-up of the included 191 patients (124 females, 67 males) was 32.13 (+/- 23.68) months and the median was 25 months. The overall recall rate was 54%. Cohen Kappa analysis revealed nearly perfect agreement between both observers (k = 0.81; p = 1.0). The overall percentage of success was 84.82% (complete healing 79.06%, incomplete healing 5.76%). The median survival was 86 months (95% CI: 56-86). None of the selected predictors had an influence on the treatment outcome (p > .05). ConclusionsOrthograde retreatment should be considered a valuable treatment option after failed apicectomy. A surgical endodontic retreatment can still be a treatment option after orthograde retreatment to obtain outcome for the patient.

Der Anteil älterer und alter Menschen an der Bevölkerung nimmt seit Jahrzehnten deutlich zu, sodass im Jahr 2030 etwa jeder dritte Mensch in Deutschland 60 Jahre oder älter sein wird. Gleichzeitig behalten unsere Patienten immer länger, oft bis ins hohe Lebensalter, ihre eigenen Zähne. Vor diesem Hintergrund wird die Wahrscheinlichkeit, dass bei einem Patienten mit einer relevanten Allgemeinerkrankung oder mit einer umfassenden medikamentösen Therapie eine Wurzelkanalbehandlung indiziert ist, in den kommenden Jahren kontinuierlich zunehmen 1. Dieser Beitrag zeigt, wann die endodontische Therapie an die gesundheitlichen Einschränkungen eines Patienten angepasst werden muss und welche Risiken mit einer endodontischen Therapie einhergehen können.

OBJECTIVES:To investigate the effect of three different calcium silicate-based materials (CSBM) on the biological behavior of human periodontal ligament stem cells (hPDLSCs). METHODS:Eluates of Biodentine, NeoPutty and TheraCal PT prepared at 1:1, 1:2, and 1:4 ratios were extracted under sterile conditions. The cytotoxicity of the extracts to the hPDLSCs was assessed using the MTT assay. Scratch wound healing assay was utilized for assessing cell migration. Scanning electron microscopy was used to detect cell attachment and morphology. Calcium ion release was measured using inductively coupled plasma-optical emission spectrometry; the pH-value was evaluated with a pH-meter. ANOVA with post hoc Tukey test was used for statistical analysis. RESULTS:Cell viability was significantly higher for Biodentine and NeoPutty at day 1 with all dilutions (p < 0.05), while at day 3 and day 7 with dilutions 1:2 and 1:4; all materials showed similar behavior (p > 0.05). Biodentine had the highest percentage of cell migration into the scratched area at day 1 for all dilutions (p < 0.05). Stem cells were attached favorably on Biodentine and NeoPutty with evident spreading, and intercellular communications; however, this was not shown for TheraCal PT. Biodentine showed the highest pH values and calcium ion release (p < 0.05). CONCLUSIONS:The resin-free CSBM showed better performance and favorable biological effects on hPDLSCs and were therefore considered promising for usage as endodontic repair materials. CLINICAL SIGNIFICANCE:Proper selection of materials with favorable impact on the host stem cells is crucial to ensure outcome in different clinical scenarios.

Introduction: To compare the biofilm-mimicking hydrogel removal efficiency of laser-activated irrigation (LAI) with five other irrigation techniques in simulated curved root canals with lateral canals. Methods: Three-dimensional-printed root canal models (60 degrees-curvature, radius 5 mm; dimension 25/.06) with a total length of 20 mm and lateral canals in all directions at 2, 5, and 8mm(diameter 0.2 mm) from the apex were filled with a colored biofilm-mimicking hydrogel. The following protocols (each 3 x 20 seconds continuous irrigation with distilled water 3 ml/20 seconds; n 5 20) were carried out: conventional needle irrigation; manual agitation ([MA], gutta-percha point 25/.06); EndoActivator (=sonically-activated irrigation EndoActivator, 25/.04); EDDY (5sonically-activated irrigation EDDY [SAI-E]; 25/.04); ultrasonically-activated irrigation and LAI (Erbium-doped Yttrium Aluminum Garnet laser; P400FL tip at canal entrance; 25 pps, 50 mJ, 300 ms). Standardized photos were taken with a microscope and the removal of the hydrogel was determined as a percentage for the entire system, the main canal and the lateral canals. Statistical analysis was performed using analysis of variance and Scheffe test (P 5.05). Results: LAI (89.3% +/- 5.9%) showed the greatest hydrogel removal followed by SAI-E (65.5% +/- 3.3%) and ultrasonically-activated irrigation (59.1% +/- 4.7%), with significant differences between these groups (P < .05). Needle irrigation, MA, and sonically-activated irrigation EndoActivator performed equally (P > .05) and obtained the significantly lowest values (P < .05). LAI and SAI-E showed the significantly best hydrogel removal from the main canal (P < .05). At all three levels, LAI removed significantly more hydrogel from the lateral canals than all other techniques (P,.05). Conclusions: LAI was superior to other techniques in both the entire systemand the lateral canals in removing the hydrogel. SAI-E achieved comparable results in the main canal.

BACKGROUND:There is tendency for unavoidable sealer extrusion in some clinical cases. This might adversely affect host stem cells and affect healing. This study aimed to investigate the effect of different sealers on the cytocompatibility and osteogenic potential of human periodontal ligament stem cells (hPDLSCs).METHODS:The cytotoxic effect of the extracted elutes of VDW.1Seal (VDW.1), Endosequence BC Sealer HiFlow (ES), GuttaFlow-2 (GF), and ADSeal (AD-S) on the hPDLSCs was determined using the MTT assay. Cell proliferation and migration were assessed by the scratch wound healing assay. Osteogenic differentiation potential was assessed. Measurement of pH values and calcium ions release was performed.RESULTS:GF had a significantly higher percentage of viable cells. The cell migration assay showed that GF demonstrated the lowest open wound area percentage. GF and AD-S showed the highest calcium nodule deposition. GF demonstrated higher ALP activity than ES. Expression of RUNX2 and OC genes was similar for all sealers, while OPG gene expression was significantly higher for VDW.1 and GF. ES and AD-S displayed the highest pH values on day 1. Calcium ion release of ES and VDW.1 was significantly the highest.CONCLUSIONS:GuttaFlow-2 and VDW.1Seal sealers have favorable behavior toward host stem cells.

The circulating low-density lipoprotein concentration in blood can be reduced by the administration of statins. Frequently simvastatin (SV) is prescribed. Due to the reported pleiotropic effects of SV the aim of this study was to evaluate mineralization effects on human adipose tissue-derived stromal cells upon administration of SV. After informed consent human adipose tissue-derived stromal cells were obtained from tissue surplus of regular treatments of 14 individuals. According to established protocols after adding various SV concentrations (0.01 µM, 0.1 µM, 1.0 µM, 2.0 µM), alkaline phosphate (osteoblastic marker), mineralization capability and viability were determined at day 18, 21 and 28. The Kruskal–Wallis test was performed for statistical analysis. After adding SV a dose-dependent significant decreased viability and levels of alkaline phosphatase (p < 0.01) and a significantly increased mineralization (p < 0.01) of the primary cultures was recognized during the late mineralization stage. Mineralization of the human adipose tissue-derived stromal cells was induced by SV, possibly originated from alternative pathways than the alkaline phosphatase pathway. Further investigations should be performed regarding switching into the osteoblastic differentiation and as a possible source of cells that can be used as the basis for a potential bone graft substitute, which may allow an extension of the field of application.

Cell cultures can provide useful in vitro models. Since odontoblasts are postmitotic cells, they cannot be expanded in cell cultures. Due to their extension into the dentin, injuries are inevitable during isolation. Therefore, "odontoblast-like" cell culture models have been established. Nowadays, there is no accepted definition of odontoblast-like cell cultures, i.e., isolation, induction, and characterization of cells are not standardized. Furthermore, no quality-control procedures are defined yet. Thus, the aim of this review was to evaluate both the methods used for establishment of cell cultures and the validity of molecular methods used for their characterization. An electronic search was performed in February 2022 using the Medline, Scopus, and Web of Science database identifying publications that used human primary odontoblast-like cell cultures as models and were published between 2016 and 2022. Data related to (I) cell culture conditions, (II) stem cell screening, (III) induction media, (IV) mineralization, and (V) cell characterization were analyzed. The included publications were not able to confirm an odontoblast-like nature of their cell cultures. For their characterization, not only a similarity to dentin but also a distinction from bone must be demonstrated. This is challenging, due to the developmental and evolutionary proximity of these two tissue types.

Background The aim was to evaluate the remineralization potential as well as the extent of protection against renewed demineralization of enamel by hydroxyapatite-containing toothpaste (Karex) in comparison to fluoride-containing (Elmex) and fluoride- and hydroxyapatite-free toothpaste (Ajona) as control. Methods Fifty-seven enamel samples were obtained from 19 human teeth. Five demarcated surfaces were created on each tooth (S0—S4). Four of the surfaces (S1—S4) were exposed to lactic acid (pH 3) for 8 h (demineralization). S0 was left untreated as control. S1 was solely treated with acid. After demineralization, S2 was exposed to Karex for 2 min, of which 15 s were brushing. S3 was treated with Elmex and S4 with Ajona, accordingly. Then, the samples were evaluated using a scanning electron microscope and ImageJ image analysis software to determine the percentage of demineralization. Afterwards, S2-S4 were again exposed to lactic acid for 2 h, and subjected to pixel analysis another time. Data were statistically analysed using ANOVA with post-hoc Scheffé test and the Kurskal-Wallis test. Results The surfaces treated with Elmex showed the lowest percentage of demineralization (mean 5.01 ± 0.98%) ( p < 0.01). Thus, Elmex remineralized more effectively compared to Ajona (8.89 ± 1.41%) and Karex (9.85 ± 1.63%) ( p < 0.01). Furthermore, Elmex showed the lowest percentage of demineralized enamel after new demineralization (median 6.29%), followed by Ajona (11.92%) and Karex (13.46%) ( p < 0.001). Conclusion In terms of remineralization and protection against renewed demineralization, a hydroxyapatite-containing toothpaste (Karex) appears to be inferior to a fluoride-containing toothpaste (Elmex) and a fluoride- and hydroxyapatite-free toothpaste (Ajona). Hence, the recommendation to use Karex to protect against demineralization should be critically questioned.

This study aimed to investigate the short- and long-term solubility, alkalizing potential, and suitability for warm-vertical compaction of AH Plus Bioceramic Sealer (AHBC), and Total Fill BC Sealer (TFBC) compared to the epoxy-resin sealer AH Plus (AHP). A solubility test was performed according to ISO specification 6876 and further similar to ISO requirements over a period of 1 month in distilled water (AD) and 4 months in phosphate-buffered saline (PBS). The pH of the immersion solution was determined weekly. Sealers were exposed to thermal treatment at 37, 57, 67, and 97 °C for 30 s. Furthermore, heat treatment at 97 °C was performed for 180 s to simulate inappropriate implementation of warm vertical filling techniques. Physical properties (setting time, flow, film thickness according to ISO 6876) and chemical properties (Fourier transformed infrared spectroscopy) were assessed. AHBC and TFBC were associated with significantly higher solubility than AHP over 1 month in AD and 4 months in PBS (p < 0.05). AHBC and TFBC both reached high initial alkaline pH, while TFBC was associated with a longer-lasting alkaline potential than AHBC. Initial pH of AHBC and TFBC was higher in AD than in PBS. None of the sealers were compromised by thermal treatment.