Implantation Angle Research Articles

P-56037191-1383 - How the angle of dental implants is affected by the experience of oral and maxillofacial surgeons?

P-56037191-1383 - How the angle of dental implants is affected by the experience of oral and maxillofacial surgeons?

Accuracy of implant abutment level digital impressions using stereophotogrammetry in edentulous jaws: an in vitro pilot study

BackgroundIn edentulous jaws, factors such as the number of implants, cross-arch distribution, and the angle among implants may affect the accuracy of the implant impression. This study explored factors influencing the accuracy of implant abutment-level digital impressions using stereophotogrammetry in edentulous jaws.MethodsTwo standard all-on-4 and all-on-6 models of edentulous jaws were constructed in vitro. In the stereophotogrammetry group (PG), the implant digital impression was made using stereophotogrammetry and saved as an STL file. In the conventional group (CNV), the impression was made using the open-tray splint impression technique. An electronic and optical 3D measuring instrument was used to scan the standard model and the conventional plaster model to obtain STL files. Using 3D data processing software (GOM Inspect Pro, Zeiss), the distance and angle between the abutments in the CNV impression and the PG impression were measured and compared with the data from the standard model.ResultsThe distance deviation in the PG and the CNV was 145 ± 196 μm and 96 ± 150 μm, respectively, with a significant difference (P < 0.001). The angle deviation in the PG and the CNV was 0.82 ± 0.88° and 0.74 ± 0.62°, respectively, with no significant difference (P = 0.267). In the PG, the distance deviation was negatively correlated with the distance between implants (r = -0.145, P = 0.028) and positively correlated with the angle of implants (r = 0.205, P = 0.002). The angle deviation was negatively correlated with the distance between implants (r = -0.198, P = 0.003) and positively correlated with the angle of implants (r = 0.172, P = 0.009). In the CNV, the effect of inter-implant distance on impression accuracy was also shown by Spearman correlation analysis: r = 0.347 (P < 0.001) for distance deviation and r = -0.012 (P = 0.859) for angle deviation. The effect of inter-implant angulation on impression accuracy deviation was r = -0.026 (P = 0.698) for distance deviation and r = 0.056 (P = 0.399) for angle deviation.ConclusionsThe CNV method is closer to the real value of the original model. The distance between implants and the distribution angle had a weak correlation with the accuracy of digital impressions but no significant correlation with the accuracy of traditional impressions.

A Multivariate Approach to Quantifying Risk Factors Impacting Stereotactic Robotic-Guided Stereoelectroencephalography.

Stereoelectroencephalography (SEEG) is an important method for invasive monitoring to establish surgical candidacy in approximately half of refractory epilepsy patients. Identifying factors affecting lead placement can mitigate potential surgical risks. This study applies multivariate analyses to identify perioperative factors affecting stereotactic electrode placement. We collected registration and accuracy data for consecutive patients undergoing SEEG implantation between May 2022 and November 2023. Stereotactic robotic guidance, using intraoperative imaging and a novel frame-based fiducial, was used for planning and SEEG implantation. Entry-point (EE), target-point (TE), and angular errors were measured, and statistical univariate and multivariate linear regression analyses were performed. Twenty-seven refractory epilepsy patients (aged 15-57 years) undergoing SEEG were reviewed. Sixteen patients had unilateral implantation (10 left-sided, 6 right-sided); 11 patients underwent bilateral implantation. The mean number of electrodes per patient was 18 (SD = 3) with an average registration mean error of 0.768 mm (SD = 0.108). Overall, 486 electrodes were reviewed. Univariate analysis showed significant correlations of lead error with skull thickness (EE: P = .003; TE: P = .012); entry angle (EE: P < .001; TE: P < .001; angular error: P = .030); lead length (TE: P = .020); and order of electrode implantation (EE: P = .003; TE: P = .001). Three multiple linear regression models were used. All models featured predictors of implantation region (157 temporal, 241 frontal, 79 parietal, 9 occipital); skull thickness (mean = 5.80 mm, SD = 2.97 mm); order (range: 1-23); and entry angle in degrees (mean = 75.47, SD = 11.66). EE and TE error models additionally incorporated lead length (mean = 44.08 mm, SD = 13.90 mm) as a predictor. Implantation region and entry angle were significant predictors of error (P ≤ .05). Our study identified 2 primary predictors of SEEG lead error, region of implantation and entry angle, with nonsignificant contributions from lead length or order of electrode placement. Future considerations for SEEG may consider varying regional approaches and angles for more optimal accuracy in lead placement.

Ten-Year Results of the Fitmore® Hip Stem with a Focus on Varus/Valgus Alignment and Subsidence-A Retrospective Monocentric Analysis.

Background: Hip arthroplasty is a common elective surgery worldwide, with rising numbers due to demographic changes and an emphasis on maintaining physical activity in the elderly. The development of new implant designs, especially shorter uncemented stems, has contributed to the advancement of minimally invasive implantation techniques. However, the long-term in vivo behaviour of these implants, particularly regarding subsidence, stability, and stress shielding, remains to be fully understood. Methods: This retrospective, monocentric cohort study analyses the long-term radiographic outcomes of the first 141 patients who underwent total hip arthroplasty with the Fitmore® Hip Stem between June 2007 and December 2008. It focuses on subsidence, stability, varus-valgus alignment, and the influence of patient-related, anatomical, and surgical factors on implant behaviour over a 10-year follow-up period. Results: The average change in varus/valgus alignment was 0.7° into varus and the average subsidence was 1.7 mm over 10 years, with most changes occurring within the first six weeks postoperatively. The varus-valgus alignment and subsidence did not significantly change after the first year, indicating stable osteointegration of the implant. Neither patient factors (gender, age) nor surgical and implant factors (implantation angle, approach, stem family, size, total offset) had a significant influence on the long-term behaviour of the implant. Conclusions: The Fitmore® Hip Stem shows highly reliable long-term stability and integration, unaffected by various patient, surgical, and implant factors, as confirmed by excellent register data. Nevertheless, monitoring of this and other new implants should be continued in order to determine implant behaviour, possible weaknesses, and indication limits at an early stage for the benefit of the patient.

Analysis of the Application Value of Dynamic Navigation Guidance in Oral Implantation.

To investigate the application of dynamic navigation guidance technology in different implantation scenarios, and to provide a scientific basis for the innovation and advancement of implantation techniques. Fifteen cases of patients with malocclusions admitted between January 2021 and February 2023 were selected as the study subjects. All patients underwent dynamic navigation-guided oral implantation interventions. CBCT scans were taken after implantation surgery to record deviations of implantation points, including implantation point deviation, endpoint deviation, and angle deviation. Dynamic navigation guidance effectively improves the reliability and stability of implantation in oral implant patients. CBCT effectively evaluated the state of the patient's periodontal implant, analyzed the state of the patient's lesion area, and improved the quality of implant intervention through CBCT guidance. The implantation point deviation was (0.407±0.193) mm, the endpoint deviation was (0.492±0.201) mm, and the implant angle deviation was (2.162±0.283)°. There was no significant difference in implantation point deviation in the anterior and posterior parts of the upper and lower jaws after intervention (P>0.05). However, there were significant differences in endpoint deviation and implant angle deviation among the anterior and posterior parts of the upper and lower jaws (P<0.05). Dynamic navigation guidance effectively improves the reliability and stability of implantation in oral implant patients. However, there is relatively greater endpoint deviation and implant angle deviation in the posterior part of the upper jaw.

High-precision all-in-one dual robotic arm strategy in oral implant surgery

IntroductionDental implantation has emerged as an efficient substitute for missing teeth, which is essential for restoring oral function and aesthetics. Compared to traditional denture repair approaches, dental implants offer better stability and sustainability. The position, angle, and depth of dental implants are crucial factors for their long-term success and necessitate high-precision operation and technical support.MethodWe propose an integrated dual-arm high-precision oral implant surgery navigation positioning system and a corresponding control strategy. Compared with traditional implant robots, the integrated dual-arm design greatly shortens the preparation time before surgery and simplifies the operation process. We propose a novel control flow and module for the proposed structure, including an Occluded Target Tracking Module (OTTM) for occlusion tracking, a Planting Plan Development Module (PPDM) for generating implant plans, and a Path Formulation Module (PFM) for controlling the movement path of the two robot arms.ResultUnder the coordinated control of the aforementioned modules, the robot achieved excellent accuracy in clinical trials. The average angular error and entry point error for five patients who underwent implant surgery using the proposed robot were 2.1° and 0.39 mm, respectively.ConclusionIn essence, our study introduces an integrated dual-arm high-precision navigation system for oral implant surgery, resolving issues like lengthy preoperative preparation and static surgical planning. Clinical results confirm its efficacy, emphasizing its accuracy and precision in guiding oral implant procedures.

Optimizing hook implantation angle of the clavicular hook plate: a cadaveric study.

While Clavicle hook plates have demonstrated favorable results regarding bone and shoulder function, their design can potentially lead to complications due to pressure concentration at the plate's tip. This study aims to investigate the impact of different hook implantation angles on the contact surface area between the hook plate and acromion, with the goal of minimizing mismatch and maximizing contact surface area. Twenty soft shoulder cadavers were included in the study, and the contact surface area of the hook plate was measured in different positions based on the hook implantation angle. The results showed variations in compatibility, width, and length of the contact surface area depending on the hook implantation angle and the medial or lateral row placement. The lateral row generally demonstrated superior compatibility (84.0% vs 46.67%, p-value < 0.001), with a broader contact area (3.55 ± 0.08 mm vs 3.09 ± 0.10 mm, p-value = 0.004) and a longer contact area (7.36 ± 0.19 mm vs 5.10 ± 0.23 mm, p-value < 0.001) at specific angles. A detailed analysis of the lateral position revealed that the zero angle of implantation resulted in the greatest contact surface area, measuring 3.91 ± 0.70 mm in width (p value = 0.083) and 8.85 ± 1.24 mm in length (p value < 0.001). Placing the hook laterally and at the zero position according to the hook implantation angle can maximize contact surface area, may reduce stress concentration, and minimize complications in hook plate fixation. Further research and consideration of anatomical variations are warranted to refine the placement technique and enhance patient outcomes. Level V evidence.

Stemless reverse shoulder arthroplasty neck shaft angle influences humeral component time-zero fixation and survivorship: a cadaveric biomechanical assessment

Stemless humeral components are being clinically investigated for reverse shoulder arthroplasty (RSA) procedures. There is, however, a paucity of basic science literature on the surgical parameters that influence the success of these procedures. Therefore, this cadaveric biomechanical study evaluated the neck shaft angle (NSA) of implantation on the survivability and performance of stemless RSA humeral components during cyclical loading. Twelve paired cadaveric humeri were implanted with stemless RSA humeral components at NSAs of 135° and 145°. Implant-bone motion at the periphery of the implant was measured with 3 optical machine vision USB3 cameras outfitted with c-mount premium lenses and quantified with ProAnalyst software. A custom 3-dimensional loading apparatus was used to cyclically apply 3 loading directions representative of physiological states at 5 progressively increasing loading magnitudes. Stemless 135° and 145° implants were compared based on the maximum implant-bone relative distraction detected, as well as the survivorship of the implants throughout the loading protocol. Primary fixation and implant biomechanical survivorship were substantially better in the 145° NSA implants. The 135° NSA implants elicited significantly higher implant-bone distractions during cyclical loading (P=.001), and implant survivorship was considerably lower in the 135° NSA specimens when compared to the 145° NSA specimens (135° NSA: 0%, 145° NSA: 50%) (P<.001). NSA is a modifiable parameter that influences time-zero implant stability, as well as the early survivorship of the stemless RSA humeral components tested in this study. NSA resections of 145° appear to promote better stability than those utilizing 135° NSAs during early postoperative eccentric loads. Further studies are required to assess if other stemless reversed humeral implant designs have improved time-zero fixation at higher NSAs.

Numerical investigation of LDL nanoparticle collision in coronary artery grafts with porous wall and different implantation angles and two state of inlet velocity.

This study aimed to reduce the risk of graft occlusion by evaluating the two-phase flow of blood and LDL nanoparticles in coronary artery grafts. The study considered blood as an incompressible Newtonian fluid, with the addition of LDL nanoparticles, and the artery wall as a porous medium. Two scenarios were compared, with constant inlet velocity (CIV) and other with pulsatile inlet velocity (PIV), with LDL nanoparticles experiencing drag, wall-induced lift, and induced Saffman lift forces, or drag force only. The study also evaluated the concentration polarization of LDLs (CP of LDLs) near the walls, by considering the artery wall with and without permeation. To model LDL nanoparticles, the study randomly injected 100, 500, and 1000 nanoparticles in three release states at each time step, using different geometries. Numerical simulations were performed using COMSOL software, and the results were presented as relative collision of nanoparticles to the walls in tables, diagrams, and shear stress contours. The study found that a graft implantation angle of 15° had the most desirable conditions compared to larger angles, in terms of nanoparticle collision with surfaces and occlusion. The nanoparticle release modes behaved similarly in terms of collision with the surfaces. A difference was observed between CIV and PIV. Saffman lift and wall-induced lift forces having no effect, possibly due to the assumption of a porous artery wall and perpendicular outlet flow. In case of permeable artery walls, relative collision of particles with the graft wall was larger, suggesting the effect of CP of LDLs.

The Association Between Trajectory-Skull Angle and Accuracy of Stereoelectroencephalography Electrode Implantation in Drug-Resistant Epilepsy

OBJECTIVETo analyze the relationship between trajectory-skull angle and stereoelectroencephalography (SEEG) electrode implantation accuracy in drug-resistant epilepsy patients, aiming to guide clinical electrode placement and enhance surgical precision and safety. METHODSWe conducted a retrospective analysis of medical records and surgical characteristics of 32 consecutive patients diagnosed with drug-resistant epilepsy, who underwent SEEG procedures at our center from June 2020 to June 2023. To evaluate the accuracy of electrode implantation, we utilized preoperative and postoperative CT scans fused with SinoPlan software-planned trajectories. Entry radial error and target vector error were assessed as measurements of electrode implantation accuracy. RESULTSAfter adjusting for confounders, we found a significant positive correlation between trajectory-skull angle and entry radial error (β=0.02, 95% CI: 0.01–0.03, P<0.001). Likewise, a significant positive correlation existed between trajectory-skull angle and target vector error in all three models (β=0.03, 95% CI: 0.01–0.04, P<0.001). Additionally, a U-shaped relationship between trajectory-skull angle and target vector error was identified using smooth curve fitting. This U-shaped pattern persisted in both frame-based and robot-guided stereotactic techniques. According to the two-piecewise linear regression model, the inflection points were 9° in the frame-based group and 16° in the robot-guided group. CONCLUSIONSThis study establishes a significant positive linear correlation between trajectory-skull angle and entry radial error, along with a distinctive U-shaped pattern in the relationship between trajectory-skull angle and target vector error. Our findings suggest that trajectory-skull angles of 9° (frame-based) and 16° (robot-guided) may optimize the accuracy of target vector error.

Predictors for new-onset conduction block in patients with pure native aortic regurgitation after transcatheter aortic valve replacement with a new-generation self-expanding valve (VitaFlow Liberty™): a retrospective cohort study

BackgroundNew-generation self-expanding valves can improve the success rate of transcatheter aortic valve replacement (TAVR) for severe pure native aortic regurgitation (PNAR). However, predictors of new-onset conduction block post-TAVR using new-generation self-expanding valves in patients with PNAR remain to be established. Therefore, this study aimed to identify predictors of new-onset conduction block post-TAVR using new-generation self-expanding valves (VitaFlow Liberty™) in patients with PNAR.MethodsIn this retrospective cohort study, patients were categorized into pacemaker and non-pacemaker groups based on their need for new postoperative permanent pacemaker implantation (PPI). Based on the postoperative presence of either new-onset complete left bundle branch block (cLBBB) or high-grade atrioventricular block (AVB), patients were further classified into conduction disorder and non-conduction disorder groups. Laboratory, echocardiographic, computed tomography, preoperative and postoperative electrocardiography, and procedural and clinical data were collected immediately after TAVR and during hospitalization and compared between the groups. Multivariate logistic regression analysis was performed incorporating the significant variables from the univariate analyses.ResultsThis study examined 68 consecutive patients with severe PNAR who underwent TAVR. In 20 patients, a permanent pacemaker was fitted postoperatively. Multivariate logistic regression analysis revealed an association between the need for postoperative PPI and preoperative complete right bundle branch block (cRBBB) or first-degree AVB, as well as a non-tubular left ventricular outflow tract (LVOT). In addition, valve implantation depth and angle of aortic root were independent predictors of new-onset cLBBB or high-grade AVB developing post-TAVR. The predictive value of valve implantation depth and angle of aortic root was further supported by receiver operating characteristic curve analysis results.ConclusionsIn patients with PNAR undergoing TAVR using self-expanding valves, preoperative cRBBB or first-degree AVB and a non-tubular LVOT were indicators of a higher likelihood of PPI requirement. Moreover, deeper valve implantation depth and greater angle of aortic root may be independent risk factors for new-onset cLBBB or high-grade AVB post-TAVR. Valve implantation depth and angle of aortic root values may be used to predict the possibility of new cLBBB or high-grade AVB post-TAVR.

Comparative subcutaneous and submuscular implantation of an electroencephalography device for long term electroencephalographic monitoring in dogs.

Implantable electroencephalography (EEG) recording devices have been used for ultra-long-term epilepsy monitoring both in clinical and home settings in people. Objective and accurate seizure detection and recording at home could be of great benefit in diagnosis, management and research in canine idiopathic epilepsy (IE). Continuous EEG monitoring would allow accurate detection of seizure patterns, seizure cycles, and seizure frequency. An EEG acquisition system usable in an "out of clinic" setting could improve owner and veterinary compliance for EEG diagnostics and seizure management. Whether a subcutaneous ultra-long term EEG monitoring device designed for humans could be implanted in dogs. Cadaver study with 8 medium to large breed dogs. Comparatively using a subcutaneous and submuscular approach to implant the UNEEG SubQ-Implant in each dog. Positioning was controlled via CT post implantation and cranial measurements were taken. In four of the eight dogs a submuscular implantation without any complications was possible. Complications were close contact to the optic nerve in the first approaches, before the implantation angle was changed and in the smallest dog contact of the implant with the orbital fat body. Cranial measurements of less than 95 mm length proved to be too small for reliable implantation via this approach. The subcutaneous approach showed severe limitations and the implant was prone to dislocation. The UNEEQ SubQ-Implant can be implanted in dogs, via submuscular approach. CT imaging and cranial measurements should be taken prior to implantation.

The lowest point of fibula (LPF) could be used as a reliable bony landmark for arthroscopic anchor placement of lateral ankle ligaments ----compared with open Broström procedure

BackgroundArthroscopic technique procedures was wide accepted for the treatment of chronic ankle instability (CAI). But little acknowledge was involved to the bony landmarks and anatomic features of different bundles of lateral ligaments under arthroscopic view.MethodsSixty patients with acute or chronic lateral ankle ligaments injury (LAI) were collected prospectively, and divided randomly into two groups. In arthroscopic group, the bone tunnels were made on the LPF arthroscopically. And in open group, the bone tunnels were made on the Fibular obscure tubercle (FOT) in open procedure. The inferior bundle of ATFL and Arcuate fibre was also identified reference to the LPF and labeled by a PDS II suture penetration. Following that, The distances of the bone tunnels to the different bony markers were measured and compare between two groups. The penetrating locations of PDS II on the inferior bundle of ATFL and Arcuate fibre were also confirmed intraoperatively. And the safe angle of anchor implantation on the axial view was measured on postoperative CT scan.ResultsThe distances of bone tunnel to the fibular tip, the fibular insertion of anterior-inferior tibiofibular ligament (AITFL), and the FOT in arthroscopic and open locating groups were 4.9 ± 2.2 and 6.3 ± 2.2 mm, 13.5 ± 2.7 and 12.4 ± 1.1 mm, 5.8 ± 2.2 and 5.6 ± 1.0 mm, respectively. The distances of bone tunnels to the FOT and fibular tip on 3d-CT view was 4.4 ± 1.5 and 4.6 ± 0.9 mm, 14.4 ± 3.2 and 13.2 ± 1.8 mm in arthroscopic and open group, and there were no significant differences between two groups. The safe angle of arthroscopic anchor placement on the axial plan was ranged from 24.9 ± 6.3o to 58.1 ± 8.0o. The PDS II sutures penetrating on the inferior bundles of ATFL and the arciform fibres were also comfirmed successfully by open visualizaion.The average distance of penetration point to the horizontal line cross the fibular tip was 2.3 ± 2.7 mm (ranged from − 3.1 to 6.0 mm), and to the vertical line cross the FOT was 2.7 ± 2.7 mm (ranged from − 2.5 to 7.5 mm).ConclusionTake the lowest point of fibula under arthroscopy (LPF) as a bony reference, we could identify the iATFL under arthroscopic visualization. By this way, we could place the suture anchors properly to the fibular footprint and suture the iATFL fibres successfully.

Dental implant brand and angle identification using deep neural networks

Determining the brand and angle of an implant clinically or radiographically can be challenging. Whether artificial intelligence can assist is unclear. The purpose of the present study was to determine the brand and angle of implants from panoramic radiographs with artificial intelligence. Panoramic radiographs were used to classify the accuracy of different dental implant brands through deep convolutional neural networks (CNNs) with transfer-learning strategies. The implant classification performance of 5 deep CNN models was evaluated using a total of 11904 images of 5 different implant types extracted from 2634 radiographs. In addition, the angle of implant images was estimated by calculating the angle of 2634 implant images by applying a regression model based on deep CNN. Among the 5 deep CNN models, the highest performance was obtained in the Visual Geometry Group (VGG)-19 model with a 98.3% accuracy rate. By applying a fusion approach based on majority voting, the accuracy rate was slightly improved to 98.9%. In addition, the root mean square error value of 2.91 degrees was obtained as a result of the regression model used in the implant angle estimation problem. Implant images from panoramic radiographs could be classified with a high accuracy, and their angles estimated with a low mean error.

Improved performance of FDSOI FETs at cryogenic temperatures by optimizing ion implantation into silicide

Band tailing is a critical issue for cryogenic CMOS, which significantly degrades the performance of conventional MOSFETs at cryogenic temperature. The band tail arises primarily due to Gaussian-distributed localized states, which can be induced by ion implantation during source/drain formation. In this study, we investigate the impact of various ion implantation schemes on the subthreshold behavior of cryogenic fully depleted (FD) SOI MOSFETs. By optimizing the ion implantation into silicide (IIS) process, we were able to reduce the density of localized states and achieve a steep switching performance at 5 K. We systematically examine the effects of ion implantation angle and activation temperature of IIS on the device performance at cryogenic temperatures.

Implant retained prosthesis on a free fibula flap: A challenging procedure for prosthetic and soft tissue management

A 39-year-old woman who had undergone fibular flap reconstruction and simultaneous implant placement after the surgical removal of a cemento-ossifying fibroma was experiencing mild discomfort 3 years later and requested an implant-supported prosthesis to restore her edentulous left maxillary quadrant. Initially, an interim removable partial denture was provided and later duplicated with clear resin. The interim prosthesis identified the excessive thickness of the grafted cutaneous soft tissue and the inadequate emergence angle of the nonfunctioning implants. By using the interim prosthesis as a surgical guide, vestibuloplasty was performed to thin the peri-implant soft tissue and the excessive skin graft from the initial maxillofacial surgery. Concurrently, the emergence angle of the implant was corrected with angled multi-unit abutments. A tissue compression stent was then made and attached to the abutments to guide the soft tissue healing process. When the peri-implant soft tissue had stabilized, a definitive implant-supported prosthesis was provided.

Stemless reverse humeral component neck-shaft angle has an influence on initial fixation

Stemless anatomic humeral components are commonly used and are an accepted alternative to traditional stemmed implants in patients with good bone quality. Presently, little literature exists on the design and implantation parameters that influence primary time-zero fixation of stemless reverse humeral implants. Accordingly, this finite element analysis study assessed the surgical implantation variable of neck shaft angle, and its effect on the primary time-zero fixation of reversed stemless humeral implants. Eight CT-derived humeral finite element models were used to examine a generic stemless humeral implant at varying neck shaft angles of 130°, 135°, 140°, 145°, and 150°. Four loading scenarios [30° shoulder abduction with neutral forearm rotation, 30° shoulder abduction with forearm supination, a head-height lifting motion, and a single-arm steering motion] were employed. Implantation inclinations were compared based on the maximum bone-implant interface distraction detected after loading. The implant-bone distraction was greatest in the 130° neck shaft angle implantation cases. All implant loading scenarios elicited significantly lower micromotion magnitudes when neck shaft angle was increased (P = 0.0001). With every 5° increase in neck shaft angle, there was an average 17% reduction in bone-implant distraction. The neck shaft angle of implantation for a stemless reverse humeral component is a modifiable parameter that appears to influence time zero implant stability. Lower, more varus, neck shaft angles increase bone-implant distractions with simulated activities of daily living. It is therefore suggested that humeral head osteotomies at a higher neck shaft angle may be beneficial to maximize stemless humeral component stability.

Accuracy of Microimplant Placement Using a 3D Guide Plate for Orthodontic Anchorage.

This study aimed to design a three-dimensional (3D) guide plate using computer-aided design and a 3D printing system for precise implantation of microimplants for orthodontic treatment and investigate the accuracy and feasibility of a 3D guide plate in clinical practice. A total of 30 microimplants were placed in 15 patients in the Department of Stomatology, Affiliated Hospital of Jiangnan University. Before surgery, DICOM data from cone-beam computed tomography (CBCT) scans and STereoLithography data from the 3D model scan were imported to 3Shape Dental System. Data fitting and matching were performed, and 3D guide plates were designed primarily focusing on the thickness of guide plates, amount of concave compensation, and dimensions of the ring. Assist implantation method was used to place the microimplants, and postoperative CBCT images were used to evaluate the position and implantation angle. The feasibility of placing microimplants and precise implantation guided by the 3D guide plate. CBCT data before and after the placement of microimplants were compared. Regarding the secure positioning of microimplants based on CBCT data, 26 implants were categorized as Grade i, four as Grade ii, and none as Grade iii. No loosening of microimplants 1 and 3 months after surgery was reported. The implantation of microimplants is more accurate under the guidance of a 3D guide plate. This technology can achieve accurate implant positioning, thus ensuring safety, stability, and improved success rates after implantation.

Clinical analysis of successful insertion of orthodontic mini-implants in infrazygomatic crest

BackgroundThe insertion positions of mini-implant in infrazygomatic crest has been reported, but due to the anatomical variation, the precise location of this site is not clear yet. This study used cone-beam computed tomography (CBCT) to analyze the position and angle of mini-implants successfully inserted in the infrazygomatic crest, with the goal of providing reference data for clinical practice.MethodsCBCT was used to image 40 mini-implants and their surrounding tissues in adult orthodontic patients who successfully underwent mini-implant insertion in the infrazygomatic crest. The insertion positions and angles of mini-implants were measured, and the thicknesses of buccal and palatal bone adjacent to the mini-implants were also recorded. Then, we proposed the position and implantation angle for infrazygomatic crest insertion. According to the position and angle, the cortical bone thickness and distance to the root of another 54 randomly selected infrazygomatic crests were recorded to verify its feasibility.ResultsIn the coordinate system, the implantation position of the 40 successful mini-implants was (-0.4 ± 2, 8.2 ± 2.5) and the implantation angle between the long axis of the mini-implant and horizontal reference plane was 56.4° ± 7.7°. The bone thicknesses on buccal and palatal sides of infrazygomatic crest adjacent to mini-implants were 4.1 ± 2.5 mm and 7.2 ± 3.2 mm, respectively, and the cortical bone thickness was 2.4 ± 0.6 mm. Among 54 infrazygomatic crests, 75.9% of them met the safety and stability requirements. When the implantation height was increased by 1, 2, and 3 mm, the proportions of implants that met requirements for success were 81.5%, 90.7%, and 94.4%, respectively. But, the proportions of eligible implants were limited at implantation angle increases of 5° and 10°.ConclusionsUsing the long axis of the maxillary first permanent molar (U6) as the vertical reference line, mini-implants could be safely inserted in the infrazygomatic crest at a distal distance of 0.4 mm and height of 8.2 mm from the central cementum-enamel junction of U6, with an implantation angle of 56.4°. The success rate increased when the implant height increased, but the proportion of eligible implantation was limited with the increase of implantation angle.

Atomic-scale observation and prediction of gallium ion implantation induced amorphization on natural diamond surface

Gallium ion implantation is an important solution to modify the physical properties of diamonds, in which the critical condition of gallium ion implantation-induced amorphization of diamond has a crucial influence on the modification effect. Therefore, this work attempts to establish an analytical prediction model of the critical implantation dose for diamond amorphization considering the acceleration voltage, implantation angle and crystal orientation. The prediction accuracy of the model is validated with the electron backscatter diffraction pattern technology. The results show that the model has a satisfactory prediction accuracy when the acceleration voltage is higher. Moreover, the atomic-scale observation of gallium ion implantation-induced amorphization of natural diamonds is realized on a spherical aberration projection electron microscope. The results presented in this work are significant to modify the natural diamond tool for service life improvement with focused ion beams in the future as well as to guide doping diamonds to manufacture n-type semiconductor diamonds.