Restorative Dentistry & Endodontics

Articles in E-pub version are posted online ahead of regular printed publication.

Research Article

Direct cellular responses of a human periodontal ligament stem cell line to root canal sealers and white mineral trioxide aggregate: an in vitro study: Atsushi Tomokiyo, Kenta Tsuchiya, Keita Ipposhi, Salvatore Sauro, Jukka P. Matinlinna, Fumiko Minowa, Hidehiko Sano, Hidefumi Maeda; Published online October 23, 2026; DOI: https://doi.org/10.5395/rde.2026.51.e45 [Epub ahead of print]

Abstract PDF Supplementary Material: Objectives
Root canal sealers may contact periodontal ligament (PDL) tissues through the apical foramen; therefore, their biological compatibility is critical for periapical healing. This study evaluated the direct cellular responses of human PDL stem cells (PDLSCs) to selected root canal sealers and white mineral trioxide aggregate (WMTA). Methods: Disc-shaped specimens of AH Plus (AH; Dentsply Sirona), GuttaFlow 2 (GF; Coltene), GuttaFlow Bioseal (Bio; Coltene), and ProRoot MTA (WMTA) were directly placed onto cultured clonal human PDLSCs (cell line 2–23). Cell viability, gene expression related to proliferation (CCND1, CCNE1), collagen synthesis (COL1, COL3), and mineralization (BMP2, OPN, CEMP1), collagen deposition, mineralized matrix formation, surface characteristics, and Ca2+ release were evaluated using MTT assay, real-time quantitative polymerase chain reaction, histochemical staining, scanning electron microscopy/ energy-dispersive X-ray spectroscopy, and ion release analysis. Results: AH exhibited marked cytotoxicity, whereas GF, Bio, and WMTA showed higher cytocompatibility. Bio significantly increased proliferation-related gene expression at 7 days. Although early collagen deposition was lower in the Bio and WMTA groups, both materials induced significantly greater mineralized matrix formation after 28 days, accompanied by upregulation of BMP2, OPN, and CEMP1. WMTA showed a rapid initial Ca2+ release, whereas Bio demonstrated a gradual and sustained release profile. Conclusions: The evaluated materials exhibited distinct cellular effects on PDLSCs. The bioceramic silicone-based sealer (Bio) demonstrated favorable cytocompatibility and promoted mineralization-related responses comparable to WMTA, suggesting its potential to support periapical tissue healing. Therefore, Bio and WMTA may enhance PDLSC viability and mineralization, supporting improved periapical healing and long-term treatment outcomes.

164 View
10 Download

Review Article

Evaluation of postoperative pain following foraminal enlargement in asymptomatic necrotic teeth undergoing root canal treatment: a systematic review and meta-analysis: Mohammad Sabeti, Seyed Mohammadreza Masoumi, Rachel Li, Mohammad Hosein Amirzade-Iranaq; Published online October 1, 2026; DOI: https://doi.org/10.5395/rde.2026.51.e40 [Epub ahead of print]

Abstract PDF: Objectives
The apical third is crucial for endodontic success, and while foraminal enlargement (FE) may enhance canal debridement, its effect on postoperative pain remains uncertain. This review aimed to determine whether FE during single-visit nonsurgical root canal treatment (NSRCT) of asymptomatic necrotic permanent teeth leads to increased postoperative pain compared with non-FE.
Methods
This systematic review followed PRISMA 2020 and was registered in PROSPERO (CRD420250652786). MEDLINE, Web of Science, Embase, and Cochrane Central were searched to May 20, 2025, for randomized controlled trials (RCTs) comparing single-visit NSRCT with and without FE. Risk of bias was evaluated with RoB 2, and meta-analysis was conducted using a random-effects model.
Results
Six RCTs involving 426 teeth were included. The overall pooled analysis demonstrated significantly greater postoperative pain in the FE group (standardized mean difference, 1.02; 95% confidence interval, 0.24–1.80; p = 0.01). The certainty of the evidence was low, primarily because of considerable inconsistency. Subgroup analyses showed statistically significant differences at 12 and 72 hours. Overall heterogeneity was substantial (I² = 92.3%) but decreased after exclusion of two influential studies without changing the direction of the pooled effect.
Conclusions
FE is associated with a significant, though transient, increase in postoperative pain during the first week following NSRCT.

767 View
27 Download

Research Articles

Optimizing post-space drying: insights from an in vitro study using standardized three-dimensional-printed models: Takanori Sakai, Hideshi Sekine, Syuntaro Nomoto, Mamoru Yotsuya, Esha Mukherjee, Hidehiko Watanabe; Published online September 18, 2026; DOI: https://doi.org/10.5395/rde.2026.51.e43 [Epub ahead of print]

Abstract PDF: Objectives
This study aimed to evaluate the efficiency of four post-space drying methods using standardized three-dimensional (3D)-printed resin tooth specimens, with emphasis on clinical implications for adhesive post retention. Methods: Maxillary central incisor models with post spaces of three diameters (1.4, 1.7, 2.0 mm) and three lengths (6.0, 9.0, 12.0 mm) were digitally designed and 3D-printed. A total of 81 specimens (n = 9 per post-space condition) were evaluated. Four drying methods were tested: air-syringe (AS), post-air-blow (PAB), paper-point (PP), and root-canal suction (RCS). Remaining moisture amount and content were quantified gravimetrically and analyzed using two-way and oneway analysis of variance with Tukey honestly significant difference (α = 0.05). Results: Drying performance depended on both geometry and technique. AS consistently left greater remaining moisture, whereas PP and RCS showed stable, efficient drying. PAB was generally effective but technique-sensitive in long, narrow geometries. Conclusions: Standardized 3D-printed models enabled reproducible evaluation of post-space drying and revealed clinically relevant limitations of commonly used methods. Selecting drying protocols tailored to post-space geometry may reduce residual moisture prior to adhesive cementing.

719 View
15 Download

Influence of osteoporosis on tissue repair promoted by different dental materials: an in vivo study in a rat model: Guilherme Ferreira da Silva, Antônio Carlos Medina Junior, Mariza Akemi Matsumoto, Roberta Okamoto, João Pedro Gasparin Tadano, João Vitor Oliveira de Amorim, Marco Antônio Húngaro Duarte, Murilo Priori Alcalde, Rodrigo Ricci Vivan; Published online September 18, 2026; DOI: https://doi.org/10.5395/rde.2026.51.e44 [Epub ahead of print]

Abstract PDF: Objectives
Osteoporosis is a prevalent metabolic disorder, and its impact on the biological response to dental materials is not fully understood. This study evaluated whether osteoporosis affects tissue repair promoted by MTA-Angelus (MTA) and an epoxy resin-based sealer containing calcium hydroxide (ER-Ca) after implantation in rat dental sockets. The null hypothesis was that osteoporosis would not impair alveolar tissue repair or bone formation. Methods: Seventy-two female rats were assigned to ovariectomized (OVX) or sham-operated (SHAM) groups (n = 36). After osteoporosis confirmation, right upper incisors were extracted, and polyethylene tubes containing MTA, ER-Ca, or left empty (control) were implanted in the sockets for 30 and 60 days (n = 6/group). Histology quantified inflammatory cells (ICs), fibroblasts (FBs), capsule thickness, and bone formation. Data were analyzed using Kruskal-Wallis and Dunn tests (p < 0.05). Results: At 30 days, the material groups showed high IC counts (50–75 and >75 cells/field), whereas the control groups exhibited lower inflammatory scores. By 60 days, ICs decreased, FB counts increased (25–50 and 50–75 cells/field), and connective tissue thickness reduced. The OVX groups exhibited higher IC counts than SHAM at both time points (p < 0.05). MTA and ER-Ca showed comparable repair patterns. Bone formation occurred in SHAM groups treated with MTA and ER-Ca at 30 days (62.3 and 63.4 μm), and in all treated groups at 60 days, except controls. Conclusions: Osteoporosis delays inflammation resolution and new bone formation during alveolar healing. However, MTA and ER-Ca demonstrate favorable biocompatibility, supporting their clinical use in osteoporotic conditions. Further research should focus on optimizing materials and adjuvant therapies to enhance bone regeneration under compromised conditions.

845 View
19 Download

Comparative evaluation of tip diameter of different gutta-percha cones according to ISO 6877 measurement method and direct measurement method: an in vitro study: Rémy Balthazard, Renaud Giess, Loïs Martrette, Jean-Marc Martrette, Marin Vincent, Éric Mortier; Published online September 17, 2026; DOI: https://doi.org/10.5395/rde.2026.51.e42 [Epub ahead of print]

Abstract PDF: Objectives
Accurate fitting of the gutta-percha master cone is essential to ensure apical sealing and the success of endodontic treatment. The purpose of this study was to analyze the dimensional variability of gutta-percha cones by assessing the conformity of their apical tip diameter to manufacturer-specified values, and to compare tip diameter (D0) determination according to ISO 6877 with a direct measurement method. Methods: Ten size 25/.06 and ten size 30/.04 gutta-percha cones from ten commercial brands were evaluated. The apical tip diameter was determined according to the ISO 6877 measurement protocol and compared with a direct measurement obtained using a profilometer. Results: A substantial number of gutta-percha cones exhibited apical tip diameters that did not correspond to manufacturer-declared values. ISO 6877-based determination of D0 yielded heterogeneous results, likely due to morphological irregularities and taper variations. In contrast, direct measurement provided more homogeneous values that were generally closer to the nominal diameter. Cones manufactured using an injection molding process demonstrated the highest dimensional consistency. Conclusions: These findings highlight the need to revise the dimensional tolerances defined by ISO standard 6877. The adoption of more precise manufacturing and quality-control processes, together with the use of direct measurement as a complementary assessment tool, may improve the reliability of the nominal dimensions of gutta-percha cones.

703 View
29 Download

Statistical Review Article

Practical considerations and methods for determining sample size to estimate a population mean: a narrative review: Mohamad Adam Bujang; Published online August 12, 2026; DOI: https://doi.org/10.5395/rde.2026.51.e41 [Epub ahead of print]

Abstract PDF: Sample size determination plays a crucial role in ensuring the validity and precision of research findings. This paper reviews the concept, rationale, and application of the sample size formula for estimating the mean of a population. It outlines the theoretical foundation, practical calculation steps, and appropriate contexts for its use in descriptive and estimation-based studies. This formula is often overlooked, as many researchers focus primarily on hypothesis testing frameworks rather than estimation approaches. Although it is a classical method, it remains highly relevant and essential in contemporary research. Therefore, this paper highlights the importance of this formula across various research settings and provides detailed guidance on how to compute the required sample size accurately. By doing so, it aims to support proper sample size planning, strengthen research design validity, and ultimately enhance the quality and credibility of scientific investigations.

952 View
50 Download

Research Article

Prevalence of periapical abscesses in psoriasis patients: a retrospective cross-sectional study: Ilan Rotstein, Joseph Katz, Simone Grandini, Giulia Malvicini, Franklin Garcia-Godoy; Published online August 10, 2026; DOI: https://doi.org/10.5395/rde.2026.51.e39 [Epub ahead of print]

Abstract PDF: Objective: This study was performed to assess the prevalence of acute periapical abscesses (PAs) in patients with psoriasis and to determine whether this relationship remains after adjusting for related systemic, behavioral, and treatment-related confounders.
Methods
A retrospective hospital-based analysis of 2,108,676 patients was conducted using de-identified clinical data. Diagnoses of psoriasis and acute PA without sinus involvement were identified using standardized coding. The association between psoriasis and acute PAs was assessed using odds ratios (ORs) with 95% confidence intervals (CIs). Multivariable logistic regression analyses were performed to adjust for diabetes, nicotine dependence, alcohol related disorders, and biologic therapy use.
Results
Among 16,084 patients with psoriasis, 224 were diagnosed with acute PAs. Psoriasis was associated with a significantly higher prevalence of acute PAs than in the overall hospital population (OR, 2.21; 95% CI, 1.94–2.53; p < 0.0001). This association remained statistically significant after adjustment for diabetes (OR, 1.40), nicotine dependence (OR, 1.31), alcohol related disorders (OR, 1.89), and biologic therapy use (OR, 1.77). Female patients and white patients with psoriasis exhibited a higher prevalence of acute PAs compared with other demographic groups.
Conclusions
Psoriasis is independently associated with an increased risk of acute PAs, even after accounting for common medical and behavioral risk factors. Greater awareness among clinicians and closer collaboration between dermatology and oral healthcare providers can facilitate earlier diagnosis and preventive treatment.

718 View
36 Download

First
Prev
Page of 1
Next
Last

Ahead-of-print articles