Restorative Dentistry & Endodontics

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

Research Articles

Impact of bacteriological testing using an anaerobic culture system on the success of non-surgical endodontic treatment: a retrospective study: Jun Nakanishi, Noriko Saito-Nakayama, Shizu Hirata-Tsuchiya, Daisuke Furutama, Ayaka Miyata-Arita, Tomoki Kawayanagi, Takuya Arita, Saki Nishihama, Tomoya Naruse, Wang Chutian, Song Bingxin, Naoki Sadaoka, Tomoki Kumagai, Kazuma Yoshida, Katsuhiro Takeda, Hideki Shiba; Published online July 16, 2026; DOI: https://doi.org/10.5395/rde.2026.51.e33 [Epub ahead of print]

Abstract PDF PubReader ePub: Objectives
Residual bacteria at the time of root canal obturation significantly influence endodontic treatment outcomes in teeth with apical periodontitis, and confirmation of bacterial elimination from the root canal prior to obturation may improve long-term prognosis. However, the contribution of root canal bacterial culture to treatment outcomes in teeth with infected root canals is debated. This study aimed to retrospectively evaluate treatment outcomes in cases in which root canal obturation was performed after confirming negative bacteriological test results.
Methods
The medical records of patients with apical periodontitis or pulp necrosis in whom root canal obturation was performed after confirming a negative bacteriological test result using an anaerobic culture system at the Department of Endodontics and Operative Dentistry at Hiroshima University Hospital between April 1, 2015, and September 30, 2023, were retrospectively reviewed. Treatment outcomes were assessed by comparing dental radiographs obtained before treatment with those obtained during the follow-up, ranging from 3 to 24 months after root canal obturation.
Results
This retrospective study included 284 teeth from 218 patients, and the success rate was 89.1%. Tooth type, number of root canals, type of treatment, preoperative radiolucency around the root apex, preoperative root canal obturation material, dentist experience, and postoperative extent of root canal obturation material did not significantly affect treatment outcomes.
Conclusions
The findings of this retrospective study suggest that infection control incorporating bacteriological examination of root canals using an anaerobic culture system may contribute to a high success rate of nonsurgical endodontic treatment, regardless of other prognostic factors.

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Diagnostic accuracy of ChatGPT-5 in evaluating root canal treatment and periapical pathosis on periapical radiographs: Waleed Almutairi, Mujahid Alnasser, Hanan Alharbi, Obadah Austah; Published online July 8, 2026; DOI: https://doi.org/10.5395/rde.2026.51.e29 [Epub ahead of print]

Abstract PDF PubReader ePub: Objectives
Artificial intelligence (AI) chatbots such as ChatGPT-5 (OpenAI) are increasingly used for dental radiograph interpretation, especially among patients seeking self-assessment. However, their diagnostic accuracy in endodontics remains unclear. Methods: This cross-sectional STARD-AI-compliant study analyzed 271 anonymized periapical radiographs of endodontically treated posterior teeth, classified as straightforward (n = 167) or complex (n = 104), using standardized ChatGPT-5 prompts. Diagnostic criteria included obturation length (short, adequate, long), presence of voids, and periapical pathosis. Results were compared to those of a panel of general dentists and a reference standard from endodontic specialists. Sensitivity, specificity, and accuracy were calculated using the McNemar test (p < 0.05). Results: ChatGPT-5 demonstrated high specificity (up to 99.3%) for normal or adequately treated findings but low sensitivity for short (13.7%) or long (0.0%) obturations, voids (9.0%–22.7%), and periapical lesions (10.5%–28.6%). Overall accuracy (54.0%–63.2%) was significantly lower than that of general dentists (76.0%–85.6%) (p < 0.001). Conclusions: Although ChatGPT-5 achieved high specificity, its low sensitivity and overall accuracy limit diagnostic reliability. Expert clinician oversight remains essential for accurate interpretation and treatment planning.

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The influence of various adhesive applicators on the bond strength to dentin: an in vitro experimental study: Ahmed Alshawi, Benin Dikmen, Fadimeana Lal, Sevda Ozel Yildiz, Ugur Erdemir; Published online June 22, 2026; DOI: https://doi.org/10.5395/rde.2026.51.e30 [Epub ahead of print]

Abstract PDF PubReader ePub: Objectives
The aim of this in vitro study was to evaluate the influence of various adhesive applicators on the microshear bond strength (µSBS) of flowable resin composite to dentin. Methods: Forty-two extracted molars were prepared as disks and divided into two groups. In the first group, GLUMA Bond Universal (Heraeus Kulzer GmbH) was applied to the tooth surface for 20 seconds using a bristle brush, while in the second group, the same adhesive was applied by the same operator using a microbrush. Photopolymerization was performed for 10 seconds using a Valo light-curing unit (Ultradent Products Inc.). Microcylindrical silicone tubes (2 mm long, 0.8 mm inner diameter) were used as molds on the bonded dentin surfaces, and Charisma Bulk Flow ONE resin composite (Heraeus Kulzer GmbH) was injected and cured for 20 seconds. Both groups underwent a µSBS test, and the failure modes were examined microscopically. Student t-test compared the failure stress between the groups (p < 0.05). Results: The bristle brush group had the highest mean stress at failure (49.09 ± 8.76 MPa) compared to the microbrush group (37.20 ± 6.77 MPa), which also had the highest percentage of adhesive failure (95.24%). Conclusions: The choice of adhesive applicator plays a significant role in determining the µSBS of flowable resin composite to dentin. It is advisable to use a bristle brush applicator when applying adhesive.

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Review Article

Educational implications of a novel system for classifying root and canal anatomy in the human dentition: a narrative review: Hany Mohamed Aly Ahmed, Paul Michael Howell Dummer; Published online May 20, 2026; DOI: https://doi.org/10.5395/rde.2026.51.e28 [Epub ahead of print]

Abstract PDF PubReader ePub: A comprehensive understanding of both the external and internal anatomy of teeth is fundamental for the effective diagnosis and management of pulp and periapical pathoses. Recent progress in noninvasive, high-resolution imaging modalities, including cone-beam computed tomography and micro-computed tomography, has significantly enhanced the ability to examine the complex morphology of dental structures. These technological advancements have facilitated a level of anatomical detail that was previously unattainable, particularly in the assessment of crown, root, and canal systems. In response to this wealth of new anatomical data, a novel classification framework has been developed, enabling the systematic coding of root and canal configurations across all tooth types. This system offers a more nuanced and comprehensive representation of root canal anatomy compared to earlier classification models. This narrative review explores the implementation of this contemporary classification scheme in education, with a particular focus on its utility in recognizing anatomical variations and accessory canals for the benefit of undergraduate and postgraduate dental students as well as general dental practitioners.

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