Vertical root fracture (VRF) is a complication in endodontically treated teeth. This study aimed to assess the clinical outcomes of treatment of 6 VRF teeth with intentional replantation and root fragment bonding with 4-methacryloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane (4-META/MMA-TBB) resin. A series of 6 complete VRF teeth (one incisor, one canine, one premolar, and 3 M) were treated through intentional replantation and root fragment bonding with 4-META/MMA-TBB resin. This study included 6 VRF teeth in 6 patients (one man and 5 women; mean age, 44 ± 8 years). All 6 teeth had VRF in the bucco-lingual direction and one tooth had concomitant VRF in the mesio-distal direction. The root thickness was classified as thick in all 6 teeth. Of the 6 VRF teeth, 4 had biting, percussion, or palpation pain, 4 had gingival swelling, 3 had sinus tracts, 3 had discomfort, and one had tooth mobility. Radiographically, 5 of the 6 teeth had periradicular radiolucent lesions, 4 of which exhibited complete regression and one of which exhibited nearly complete regression after root fragment bonding therapy. Because all 6 treated teeth exhibited sound function in the oral cavity after a follow-up period ranging from 33 to 74 (mean, 50 ± 15) months, the clinical outcomes were all considered to be successful. For a VRF tooth, in addition to tooth extraction, intentional replantation combined with root fragment bonding with 4-META/MMA-TBB resin is a successful treatment modality that can be used to preserve a complete VRF tooth.

Background/purpose: Chronic fatigue root fracture describes a root fracture in a non-root canal treated (non-RCT) tooth. This study aimed to report the incidence and contributing factors of non-RCT teeth with chronic fatigue root fracture in a Taiwanese population. Methods: This cross-sectional study included teeth extracted at Taipei Veterans General Hospital in Taiwan between 2018 and 2019. The reasons for extractions were recorded and included vertical and horizontal root fractures (VRF and HRF). Comparisons of clinical factors between teeth with fatigue VRF and teeth with fatigue HRF were performed by chi-square or Results: Of the 4207 extracted teeth examined, 263 (6.25%) had tooth fracture. Thirty-two non-RCT teeth had chronic fatigue root fracture, including 16 with VRF and 16 with HRF. The incidence was 0.76% (32/4207). The occurrence of chronic fatigue root fracture was higher in males (83.9%). The mean age of the 31 patients with chronic fatigue root fracture was 71.7 +/- 13.1 years. More than half of these teeth had intact crowns with severe attrition. The fatigue VRF occurred more frequently in molars (P = 0.003), in roots with a long oval cross-section (P = 0.037), and in terminal teeth (P = 0.013) than the fatigue HRF. Conclusion: The incidence of chronic fatigue root fracture is 0.76%. Both VRF and HRF occur mainly in aged males, in posterior teeth with attrition, and in teeth without restoration. Tooth position, cross-section root morphology, and terminal tooth are contributing factors related to

Robotic technologies are increasingly used in dentistry for their precision in delicate procedures. While most dental robots focus on implant surgery, automating root canal treatment (RCT) remains challenging due to the need to guide a thin, flexible endodontic file through a narrow, curved root canal without causing ledging or file fracture. Patient movements—particularly those that induce additional file bending during insertion—further complicate robot-assisted procedures. This study presents an autonomous approach for root canal cleaning and shaping by combining force admittance and position tracking. A novel Patient Tracking Module, which connects the patient’s dental brace to the robot end-effector via string potentiometers, is developed to estimate real-time robot-patient pose. Additionally, a file flexibility model is proposed to predict and compensate for file deflection during insertion. A hybrid position/force control strategy, which integrates these estimations, autonomously guides file manipulation, minimizes misalignment, and therefore reduces the risk of file fracture. Experimental validation demonstrates the system’s feasibility and potential for clinical application in precision endodontic procedures. Note to Practitioners—This paper addresses the challenge of automating root canal treatment in robot-assisted endodontics, which is complicated by unpredictable patient movements and bending of endodontic files. The proposed system follows a structured workflow: (1) the dentist first diagnoses the case, labels the working length of the canal on preoperative cone-beam computed tomography (CBCT) scans, and performs access opening to the pulp chamber; (2) a custom-designed tooth brace is then installed; (3) the endodontic file held by the robot is aligned with the root canal entrance; (4) the robot is connected to the patient via a string-based Patient Tracking Module (PTM); and (5) the robot autonomously performs canal cleaning and shaping until the working length is reached. The PTM estimates patient movement in real time and compensates for it. Combined with force sensing and file deflection compensation, the system dynamically adjusts the surgical path to maintain alignment and reduce the risk of file fracture. This improves procedural safety, precision, and efficiency. Preclinical tests on acrylic models and 3D-printed teeth show promising results, but further validation in live patient settings is needed. Future work will explore automating additional steps, such as access opening and obturation, to enhance the overall treatment workflow.

Stains produced by bacteria or those found in blood and food byproducts accumulate in highly porous caries lesions. They can interfere with accurate diagnosis and the selective removal of carious tissue during cavity preparations. Short-wavelength infrared (SWIR) imaging studies have shown that stain molecules do not absorb light beyond 1200 nm. The objective of this study was to image affected and infected dentin atSWIR wavelengths. Sections of 3 mm thickness were cut from the extracted teeth with deep dentinal lesions. The sound (normal), affected (stained), and infected (demineralized) dentin on each section were examined with reflected light at wavelengths from 400 to 1700 nm, red and green fluorescence, and with optical coherence tomography (OCT). Microcomputed tomography (microCT) was used to measure the mineral density at each location investigated. Significant (p < 0.05) differences were observed in the reflected light intensity at 400–850 nm and for fluorescence between the sound, affected, and infected dentin. SWIR imaging did not show significant reductions in reflectivity for the affected and infected dentin. SWIR images may be valuable for monitoring the lateral spread of dentinal lesions on the occlusal surfaces of teeth.