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Statement of problem: The demand for immediate implant placement (IIP) in the esthetic zone is rapidly increasing. Despite the treatment's benefits, the sagittal root position often dictates implant angulation, commonly necessitating the use of cement-retained restorations. This study investigates the impact of angulated screw channel on IIP in the esthetic zone. Purpose: The purpose of this cone-beam computed tomography (CBCT) study was to determine the probability of IIP in the esthetic zone, using four different implant angulations. Materials and methods: A retrospective review of CBCT images was conducted and accessed on 9 June 2021. The midsagittal images of maxillary anterior teeth were input into an implant planning software (Implant Studio®). Bone Level X Straumann® implant (BLX 3.5, 3.75, 4.0, 4.5, 5.0 mm) and Bone Level Tapered implant (BLT 2.9, 3.3 mm) were selected for 3D implant planning of IIP in the esthetic zone. The frequency distribution and probability of IIP were recorded and compared among all maxillary anterior teeth. Results: CBCT images from 720 teeth (120 patient) were evaluated, revealing an overall probability of IIP in the esthetic zone is 76.11% (548/720). Different implant restoration type was evaluated in this study, with the following results; straight screw-retained prosthesis at 3.47% (19/548), cement-retained prosthesis at 14.59% (80/548) and angle screw-retained prosthesis at 85.40% (468/548). Conclusion: IIP with traditional straight screw-retained prosthesis demonstrated the lowest probability. Nevertheless, the use of angulated screw channels enhances the probability of achieving straight screw-retained prostheses. Clinical implications: The angulated screw channel is essential for increasing the probability of screw-retained prosthesis in IIP in the esthetic zone. However, limitation in screw angle correction still necessitate the use of cement-retained prostheses for numbers of patients undergoing IIP. [ABSTRACT FROM AUTHOR]

Objectives: Diffusion tensor imaging (DTI) can provide structural information and objective values for nerves. The aims of this study were to perform quantitative evaluation and fibre tracking of the normal inferior alveolar nerve (IAN) using DTI on 3.0-T MRI., Methods: DTI was applied to 92 IANs of 46 healthy volunteers. Circular regions of interest (ROIs) were placed on three different positions at the mandibular foramen, second molar and mental foramen of each nerve on apparent diffusion coefficient (ADC) and fractional anisotropy (FA) maps, and the ADC and FA of each ROI were measured. Differences in the values arising from the nerve positions were evaluated. Furthermore, fibre tracking of the IANs was performed by tractography, and the quality of visualization was evaluated., Results: There were no significant differences in the ADC and FA between the right and left sides regardless of the anteroposterior positions. Regarding differences arising from the anteroposterior measurement positions, the ADC and FA showed no significant differences (p > 0.017), except for the ADCs between the positions at the mandibular foramen and mental foramen in the left side (p = 0.0068). Overall, 70 (76%) of the 92 IANs could be visualized fully or partially by tractography., Conclusions: The ADC and FA of the IAN were successfully obtained from healthy volunteers using DTI and were confirmed to be symmetrical regardless of the measurement positions. DTI is a feasible technique for the quantitative evaluation and visualization of the IAN.