Purpose: This study aimed to evaluate the effect of different coronal restoration methods on stresses in immature central incisors with regenerative endodontic treatment and excessive loss of coronal structure. Methods: A three-dimensional (3D) Finite Element Analysis (FEA) model of a maxillary central incisor treated with a 3 mm MTA coronal plug after regenerative endodontic treatment was created. Six different models were simulated: (1) intact immature tooth (control), (2) direct composite resin build-up, (3) fibre-reinforced composite build-up, (4) hybrid ceramic endocrown, (5) LiSi ceramic endocrown, and (6) endocore and ceramic crown restoration. Analyses were performed with SolidWorks/CosmosWorks, and a 150 N load was applied at a 135° angle. Results: Maximum tensile stresses were concentrated in the cervical region (4.577 MPa). Direct composite and fibre-reinforced restorations showed high stress in root dentin (3.891 and 3.841 MPa, respectively). The endocore/ceramic crown restoration (1.578 MPa) provided the closest stress distribution to the natural tooth (1.322 MPa). Conclusions: The biomechanical performance of the restoration–tooth complex depends on both the restorative material and the restoration design. In immature teeth undergoing regenerative endodontic treatment, the most biomechanically favourable restoration option was an endocore/ceramic crown.

This study aimed to evaluate the biomechanics of maxillary first molar teeth following palatal, disto-buccal, and mesio-buccal root amputation. An intact maxillary molar underwent root canal treatment using Reciproc R25 files (VDW, Munich, Germany). The canals were obturated with gutta-percha (DiaDent, Seoul, Republic of Korea) and 2Seal sealer (VDW, Munich, Germany), and the access cavity was restored with composite resin. A high-resolution CBCT scan of an intact maxillary first molar was obtained using a Planmeca Promax 3D Max system (Planmeca Oy, Helsinki, Finland) at 75 kVp and 10 mA. The acquired data were processed in 3D Slicer software (v5.8.0, BSD license, Boston, MA, USA) to segment enamel, dentin, and pulp based on pixel density variations using the three-point cloud method. A baseline intact model and three root-resected models (palatal, disto-buccal, mesio-buccal) were reconstructed in SolidWorks 2021, with resected roots simulated as being sealed with MTA. Finite element analysis was conducted in CosmosWorks to evaluate von Mises stress distribution under a 300 N static occlusal load. Maximum von Mises stresses were detected at occlusal force application sites. Among root dentin tissues, stress values ranked highest after palatal root resection, followed by the mesio-buccal, disto-buccal, and non-resected models. Conclusions: Palatal root amputation of maxillary first molars generated the highest von Mises stresses in root dentin, suggesting a higher biomechanical risk than disto-buccal or mesio-buccal resections.

Amaç: Bu çalışmanın amacı, tek bir endodontist tarafından kullanılan Reciproc Blue R25 NiTi aletlerdeki kırık ve deformasyon tiplerini stereomikroskop ve taramalı elektron mikroskobu ile analiz etmektir. Gereç ve Yöntem: Çalışmada yaklaşık olarak 4 aylık bir dönemde endodonti kliniğinde 5 molar dişte tek bir endodontist tarafından kullanılmış ve imha edilmek üzere ayrılmış 47 adet Reciproc Blue R25 NiTi alet kullanıldı. Ultrasonik olarak temizlenip, otoklavlanan aletler deformasyon ve kırıkları belirlemek için stereomikroskopta x2,5 ve x4 büyütmede incelendi. Deformasyon şekilleri 1:Kırık, 2:Eğenin yivlerinin açılması/burulması, 3:Sağlam (gözle görülür bir defekt yok) şeklinde sınıflandırıldı. Kırılan eğeler torsiyonel ve fleksural kırılma olarak iki alt grupta sınıflandırıldı. Kırılan ve deforme olan aletler longitudinal ve fraktografik olarak SEM’de incelendi. Bulgular: Stereomikroskopta incelenen toplam 47 Reciproc Blue R25 eğenin % 6,3’ünde (3) kırık gözlendi, % 86,3’nde gözle görülür bir deformasyon gözlenmedi, % 4,2’ sinde torsiyonal, % 2,1’inde fleksural kırık gözlendi. Sonuç: Bu çalışmanın limitasyonları dahilinde, Reciproc Blue R25 eğesinin tek bir endodontist tarafından 5 molar dişe kadar kullanımında kırılma riski düşük bulunmuştur. Anahtar kelimeler: Deformasyon, NiTi eğeler, Kırık, Klinik kullanım

Introduction: Fear of root canal treatment (RCT) may affect care seeking and treatment experience but is often summarized using anxiety scores. This study identified fear severity patterns and trigger-content profiles and examined associations with avoidance and negative experiences. Materials and Methods: In this single-center cross-sectional study, 219 of 247 adults scheduled for primary RCT were analyzed after 28 exclusions. Preoperative anxiety was measured using a 0–10 cm Visual Analog Scale for Anxiety (VAS-A). Hierarchical cluster analysis identified fear severity patterns, and latent class analysis identified trigger-content profiles among participants endorsing at least one trigger. Results: At least one trigger was endorsed by 75.8%; 21.9% had severe anxiety (VAS-A ≥ 7.0). Severe anxiety increased descriptively from 1.9% with no trigger to 54.3% with three or more triggers. Hierarchical clustering identified low-fear (n = 152) and high-fear (n = 67) patterns. In bivariate comparisons, high-fear membership was more common among women, participants postponing dental visits, and those with negative childhood or adult RCT experiences, and less common among regular dental attenders. Hierarchical multivariable logistic regression showed that female sex and negative adult RCT experience were associated with higher odds of high-fear pattern membership, whereas regular dental attendance was associated with lower odds; negative childhood RCT experience and postponement were not independently significant in the fully adjusted model. Latent class analysis yielded needle-focused (n = 38) and procedural (n = 128) profiles; the latter showed a broader trigger range, while VAS-A distributions were similar. Conclusions: Fear of RCT was heterogeneous. Assessing severity, triggers, and avoidance history may support individualized communication. The profiles require external validation before use.

Local cooling may supplement endodontic anesthesia, but its intrapulpal thermal effects remain incompletely characterized. This in vitro study compared peak intrapulpal temperature reduction (ΔT), recovery from the temperature minimum, and maximum cooling rate for gauze-wrapped ice, an Endo-Frost-cooled cotton pellet, and a direct ice stick across unprepared, 2 mm, and 4 mm cavity-preparation conditions. Ten extracted mandibular first molars received 10 applications per protocol and condition. Intrapulpal temperature was recorded every second with the roots in a 37.0 ± 0.1 °C water bath. Outcomes were analyzed using linear mixed-effects models. Protocol, preparation condition, and their interaction affected ΔT (all p < 0.001); estimated reductions increased with preparation depth and ranged from 3.67 to 5.06 °C for direct ice, 4.59 to 6.43 °C for gauze-wrapped ice, and 10.24 to 13.32 °C for the cooled pellet. Recovery to 50, 75, and 100% of the maximal drop showed significant protocol-by-condition interactions (all p ≤ 0.022). Gauze-wrapped ice had the shortest minimum-to-baseline recovery interval at every condition (all p < 0.001 versus the other protocols), whereas the cooled pellet had the highest pooled estimated maximum cooling rate. These findings do not establish clinical anesthetic efficacy or an isolated effect of remaining dentin thickness.