Immediate Implant Placement in the Maxillary Aesthetic Zone: A Cone Beam Computed Tomography Study

This study aimed to investigate the factors that could be associated with the risk of labial cortical bone wall perforation with immediate implant placement (IIP) in the maxillary aesthetic zone, in a cone-beam computed tomography (CBCT) virtual study. CBCT exams from 126 qualified subjects (756 teeth) were included. Implants were virtually positioned in two different positions: in the long axis of the tooth (prosthetically-driven position) and in an ideal position in relation to adjacent anatomical structures (bone-driven position). Two different implant diameters were planned for each tooth position, namely, 3.75 and 4.3 mm for central incisors and canines, and 3.0 and 3.3 mm for lateral incisors. The incidence of perforation was nearly 80% and 5% for prosthetically- and bone-driven position, respectively. Factors associated with a higher risk of cortical bone wall perforation (bone-driven position), according to logistic regression analysis, were women, wider implants, Sagittal Root Position class IV, and decrease of the labial concavity angle. Perforation of the labial cortical bone wall can be greatly minimized when the implant is placed in a bone-driven position compared to a prosthetically-driven position. It is important to preoperatively evaluate the morphological features of the implant site for risk assessment and to individualize the treatment plan.

Oral rehabilitation using immediate implant placement in mandibular lateral incisors – a case report

Background: Dental problems often lead to missing teeth. After tooth extraction, the alveolar bone will undergo a healing phase, and this will cause some vertical and horizontal resorption. Immediate implant placement can shorten treatment time and preserve the rest of the alveolar bone. Purpose: The purpose of this study is to present a case of oral function, equilibrium and aesthetic rehabilitation using immediate implant placement. Case: A male patient aged 31 came to Dental Hospital Universitas Airlangga with a fractured anterior tooth. The tooth had fractured two weeks before he came to the hospital, and he wanted to improve his appearance. Case management: The mandibular incisor was fractured, and its residual root remained. The treatment plan was to undertake an immediate implant placement. The type of implant chosen was a bone level tapered implant SC roxolid® SLA Ø 2.9 mm and 10 mm long. Surgery was performed in two stages. The first stage was to extract the residual root, position the implant and apply the bone graft. The second stage was to position the healing abutment. A crown impression was made using the closed tray technique. The crown was cemented to the abutment. Conclusion: Immediate implant placement is an aesthetic means of rehabilitating a missing tooth, such as an anterior mandibular tooth.

Influence of sagittal root positions on the stress distribution around custom-made root-analogue implants: a three-dimensional finite element analysis

Background Stress concentration may cause bone resorption even lead to the failure of implantation. This study was designed to investigate whether a certain sagittal root position could cause stress concentration around maxillary anterior custom-made root-analogue implants via three-dimensional finite element analysis. Methods The von Mises stresses in the bone around implants in different groups were compared by finite element analysis. Six models were constructed and divided into two groups through Geomagic Studio 2012 software. The smooth group included models of unthreaded custom-made implants in Class I, II or III sagittal root positions. The threaded group included models of reverse buttress-threaded implants in the three positions. The von Mises stress distributions and the range of the stresses under vertical and oblique loads of 100 N were analyzed through ANSYS 16.0 software. Results Stress concentrations around the labial lamella area were more prominent in the Class I position than in the Class II and Class III positions under oblique loading. Under vertical loading, the most obvious stress concentration areas were the labial lamella and palatal apical areas in the Class I and Class III positions, respectively. Stress was relatively distributed in the labial and palatal lamellae in the Class II position. The maximum von Mises stresses in the bone around the custom-made root-analogue implants in this study were lower than around traditional implants reported in the literature. The maximum von Mises stresses in this study were all less than 25 MPa in cortical bone and less than 6 MPa in cancellous bone. Additionally, compared to the smooth group, the threaded group showed lower von Mises stress concentration in the bone around the implants. Conclusions The sagittal root position affected the von Mises stress distribution around custom-made root-analogue implants. There was no certain sagittal root position that could cause excessive stress concentration around the custom-made root-analogue implants. Among the three sagittal root positions, the Class II position would be the most appropriate site for custom-made root-analogue implants.

A Critical Review of the Differential Diagnosis of Root Fracture Line in CBCT scans

The objective of this critical review of literature is to discuss relevant clinical factors associated with root fractures (RF) visualized by using a new CBCT software. RF constitutes a common occurrence and a challenge in clinical practice, in which the diagnosis becomes essential for the definition of rapid and precise decision-making. The characterization of RF may involve different aspects, such as orientation of the fracture line (horizontal, vertical, oblique), root position of the fracture (cervical, middle, apical third), fracture's coronal-radicular position (coronary, coronal-radicular, radicular), continuity of the fracture (crack, incomplete fracture, complete), bone extension of the fracture (supraosseous, bone level, infraosseous fracture). Imaging examinations have been routinely used to aid in the RF diagnosis. Even with high-resolution cone-beam computed tomography (CBCT) scans, many doubts often remain about the diagnostic outcome. Many interferences in the analysis of image quality to determine the diagnosis are identified, such as the sharpness, the noise, light and dark artifacts, among others. The professional's knowledge is essential for identifying the different patterns of fracture lines and their repercussions on adjacent bone tissues, as well as for the analysis of artifacts that may hide or show similarities to fracture lines. Fractures lines and root fractures that may be associated with phantom conditions that mimic fractures should be carefully analyzed. CBCT is the exam indicated to identify a root fracture. It is also added to the success of the diagnosis that the professional has scientific knowledge, training and mastery of advanced CBCT software.

Potential Circumferential Bone Engagement following Tooth Extraction in the Posterior Mandible: Computed Tomography Assessment

Background and Objectives: Immediate implant placement (IIP) is a popular surgical procedure with a 94.9–98.4% survival rate and 97.8–100% success rate. In the posterior mandible, it poses a risk of injury to adjacent anatomical structures if the implant engages apical bone. This study sought to assess the implant dimensions that allow for circumferential bone engagement at each position in the posterior mandible without additional apical drilling. Materials and Methods: An observational, cross-sectional study design was used. The pre-extraction cone beam computed tomography scans of 100 candidates for IIP were analyzed. Measurements of each root of the posterior mandibular second premolar, first molar, and second molar were taken from three aspects: buccolingual, mesiodistal, and vertical. Two-sided p values < 0.05 were considered statistically significant. Results: A total of 478 mandibular teeth and 781 roots were assessed. Based on Straumann® BLX/BLT implant-drilling protocols, predicted rates of radiological circumferential engagement (RCE) were 96% for implants 5 mm in diameter in the second premolar root position; 94% for implants 4.0–4.2 mm in diameter in the first molar root position; and 99% for implants 4.5–4.8 mm in diameter in the second molar root position. Corresponding rates of achieving an available implant length (AIL) of 10 mm were 99%, 90%, and 86%. Patients <40 years old were at higher risk of lower RCE and lower AIL (p < 0.005) than older patients for all roots measured. Conclusions: The high primary stability prediction rates based on the calculation of RCE and AIL support the use of IIPs without further apical drilling in the posterior mandible in most cases.

A Novel Method of Hyperbola Recognition in Ground Penetrating Radar (GPR) B-Scan Image for Tree Roots Detection

Ground penetrating radar (GPR), as a newly nondestructive testing technology (NDT), has been adopted to explore the spatial position and the structure of the tree roots. Due to the complexity of soil distribution and the randomness of the root position in the natural environment, it is difficult to locate the root in the GPR B-Scan image. In this study, a novel method for root detection in the B-scan image by considering both multidirectional features and symmetry of hyperbola was proposed. Firstly, a mixed dataset B-Scan images were employed to train Faster RCNN (Regions with CNN features) to obtain the potential hyperbola region. Then, the peak area and its connected region were filtered from the four directional gradient graphs in the proposed region. The symmetry test was applied to segment the intersecting hyperbolas. Finally, two rounds of coordinate transformation and line detection based on Hough transform were employed for the hyperbola recognition and root radius and position estimation. To validate the effectiveness of this approach for tree root detection, a mixed dataset was made, including synthetic data from gprMax as well as field data collected from 35 ancient tree roots and fresh grapevine controlled experiments. From the results of hyperbola recognition as well as the estimation for the radius and position of the root, our method shows a significant effect in root detection.