Angular Deviation Research Articles

Effect of fence tray matching care on excess adhesive and bracket placement accuracy for orthodontic bonding: an in vitro study

ObjectiveThis study aimed to evaluate the effect of fence tray matching care (FTMC) in bracket bonding by measuring excess adhesive, as well as linear and angular deviations, and by comparing it with the half-wrapped tray (HWT).Materials and methodsAn intraoral scanner was used to acquire data on the maxillary dental arch of a patient with periodontitis.Furthermore, 20 maxillary dental arch models were 3D printed. Using 3Shape, PlastyCAD software, and 3D printing technology, 10 FTMC (method I) and HWT (method II) were obtained. By preoperative preparation, intraoperative coordination, and postoperative measurement, the brackets were transferred from the trays to the 3D-printed maxillary dental arch models. Additionally, the bracket’s excess adhesive as well as linear and angular deviations were measured, and the differences between the two methods were analyzed.ResultsExcess adhesive was observed in both methods, with FTMC showing less adhesive (P< 0.001), with a statistical difference. Furthermore, HWT’s vertical, tip and torque, which was significantly greater than FTMC (P< 0.05), with no statistical difference among other respects. The study data of incisors, canines, and premolars, showed that the premolars had more adhesive residue and were more likely to have linear and angular deviations.ConclusionsThe FTMC had higher bracket bonding effect in comparison to HWT, and the adhesive residue, linear and angular deviations are smaller. The fence tray offers an intuitive view of the precise bonding of the bracket, and can remove excess adhesive to prevent white spot lesions via care, providing a different bonding method for clinical applications.

Accuracy of the novel digital non-cross-arch surgical guides with integration of tooth undercut retention and screw-bone support for implant placement in mandibular free-end

BackgroundLarge cross-arch free-end surgical guides can obscure the visual field, compromising surgical accuracy due to insufficient stability at the free-end. This in vitro study aims to evaluate the accuracy of novel digital non-cross-arch surgical guides designed for implant placement at the mandibular free-end, incorporating tooth undercut retention and screw-bone support.Materials and methodsA mandibular dental model lacking left molars was utilized to fabricate unilateral (cross-arch) tooth-supported surgical guides (GT I, n = 20). Subsequently, two additional types of surgical guides were fabricated: GT II (covering two teeth, n = 20) and GT III (covering three teeth, n = 20). These novel surgical guides were designed to utilize the undercut of the supporting teeth for retention and enhance stability with screw-bone support at the guide’s free-end. Furthermore, 60 identical guiding blocks were assembled on the three types of surgical guides to facilitate the implants’ insertion. On a phantom head, 120 implant replicas were placed at the Federal Dentaire Internationale (FDI) teeth positions #36 and #37 on the dental model, employing a combination of surgical guides and guiding blocks. To assess accuracy, planned and placed implant positions were compared using intraoral optical scanning. Discrepancies in angulation and linear deviations, including the coronal/apical 3D deviations, lateral deviation as well as depth deviation, were measured. Statistical analysis was performed using two-way ANOVA and Bonferroni test (α = 0.05).ResultsGT I exhibited significantly largest discrepancies, including angular and linear deviations at the crest and apex at every implant site. Especially in depth, at implant site #36, the mean deviation value of GT I (0.27 ± 0.13 mm) was twice as large as GT III (0.13 ± 0.07 mm), and almost twice as large as GT II (0.14 ± 0.08 mm). However, at implant site #37, this deviation increased to almost a five-fold relationship between GT I (0.63 ± 0.12 mm) and II (0.14 ± 0.09 mm), as well as between GT I and III (0.13 ± 0.09 mm). No significant discrepancies existed between the novel surgical guides at either implant site #36 or #37.ConclusionThis study provides a practical protocol for enhancing accuracy of implant placement and reducing the size of free-end surgical guides used at mandibular molar sites.

Transfer accuracy of 3D printed versus CAD/CAM milled surgical guides for temporary orthodontic implants: A preclinical micro CT study

ObjectivesTemporary anchorage devices (TADs) have become an integral part of comprehensive orthodontic treatments. This study evaluated the transfer accuracy of three-dimensional (3D) printed and computer-aided design/computer-aided manufacturing (CAD/CAM) milled surgical guides for orthodontic TADs using micro-computed tomography (CT) imaging in a preclinical trial. MethodsOverall, 30 surgical guides were used to place TADs into typodonts; 3D printing and CAD/CAM milling were used to produce the guides. The virtual target positions of the TADs were compared to the real positions in terms of spatial and angular deviations using digital superimposition. Micro-CT imaging was used to detect the positions. To evaluate reliability, two investigators collected the measurements twice. Intra-rater and inter-rater correlations were tested. ResultsIn total, 60 palatal TADs were evaluated. The mean coronal deviations in the print group ranged from 0.15 ± 0.20 mm to 0.71 ± 0.22 mm, whereas in the mill group, they ranged from 0.09 ± 0.15 mm to 0.83 ± 0.23 mm. At the apical tip, the overall deviations in the print group ranged from 0.14 ± 0.56 mm to 1.27 ± 0.66 mm, whereas in the mill group, they ranged from 0.15 ± 0.57 mm to 1.09 ± 0.44 mm. The mean intra-class and inter-class correlation coefficients ranged from 0.904 to 0.987. No statistically significant differences were found between the groups. ConclusionsCAD/CAM milled guides yielded spatial and angular accuracies comparable to those of 3D printed guides with notable deviations in the vertical positioning of TADs. Clinical significanceDigital planning of orthodontic temporary implants combines clinical predictability and the safety of surrounding tissue. Therefore, the transfer accuracy of the guides is crucial. This preclinical study was the first to evaluate CAD/CAM milling for orthodontic guides and found its accuracy comparable to that of the current "gold standard".

Accuracy analysis of robotic-assisted immediate implant placement: A retrospective case series

ObjectivesThis study aimed to investigate the accuracy of a robotic computer-assisted implant surgery (r-CAIS) for immediate implant placement. MethodsPatients requiring immediate implant placement in the maxillary anterior region were enrolled for r-CAIS. Before surgery, the patients underwent a cone beam computed tomography (CBCT) scan with a positioning marker. Virtual implant placement position and drilling sequences were planned. Following spatial registration and calibration, the implants were placed with the robotic system under supervision. A postoperative CBCT was taken to control the actual implant positions. The DICOM data of the virtually planned and the actually placed implant were superimposed and registered through the accuracy verification software of the robotic system. The accuracy was calculated automatically. The deviation at the mesial–distal, labial–palatal, and apico-coronal directions were recorded. ResultsFifteen patients with 20 implants were included. No adverse surgical events or postoperative complications were reported. The global platform, apex, and angular deviation were 0.75 ± 0.20 mm (95 % CI: 0.65 to 0.84 mm), 0.70 ± 0.27 mm (95 % CI: 0.57 to 0.82 mm), and 1.17 ± 0.73° (95 % CI: 0.83 to 1.51°), respectively. Moreover, the vertical platform and apex deviation were 0.50 ± 0.31 mm, (95 % CI: 0.35 to 0.64 mm) and 0.48 ± 0.32 mm, (95 % CI: 0.33 to 0.63 mm), respectively. All the placed implant positions were further labial and apical than the planned ones, respectively. ConclusionsHigh accuracy of immediate implant placement was achieved with the robotic system. Clinical significanceOur study provided evidence to support the potential of the robotic system in implant placement, even in challenging scenarios.

Accuracy of implant placement using a mixed reality-based dynamic navigation system versus static computer-assisted and freehand surgery: An in Vitro study

PurposeThis in vitro study aimed to compare the accuracy of dental implant placement in partially edentulous maxillary models using a mixed reality-based dynamic navigation (MR-DN) system to conventional static computer-assisted implant surgery (s-CAIS) and a freehand (FH) method. MethodsForty-five partially edentulous models (with teeth missing in positions #15, #16 and #25) were assigned to three groups (15 per group). The same experienced operator performed the model surgeries using an MR-DN system (group 1), s-CAIS (group 2) and FH (group 3). In total, 135 dental implants were placed (45 per group). The primary outcomes were the linear coronal deviation (entry error; En), apical deviation (apex error; Ap), XY and Z deviations, and angular deviation (An) between the planned and actual (post-surgery) position of the implants in the models. These deviations were computed as the distances between the stereolithographic (STL) files for the planned implants and placed implants captured with an intraoral scanner. ResultsAcross the three implant sites, the MR-DN system was significantly more accurate than the FH method (in XY, Z, En, Ap and An) and s-CAIS (in Z, Ap and An), respectively. However, S-CAIS was more accurate than MR-DN in XY, and no difference was found between MR-DN and s-CAIS in En. ConclusionsWithin the limits of this study (in vitro design, only partially edentulous models), implant placement accuracy with MR-DN was superior to that of FH and similar to that of s-CAIS. Statement of Clinical RelevanceIn vitro, MR-DN showed greater accuracy in implant positioning than FH, and similar accuracy to s-CAIS: it could, therefore, represent a new option for the surgeon. However, clinical studies are needed to determine the feasibility of MR-DN.

Pediatric ACL Reconstruction in Children-An Evaluation of the Transphyseal Technique's Efficacy and Safety.

Injuries of the anterior cruciate ligament (ACL) are commonly found in the general population, both among adult and pediatric patients, and their incidence has been increasing in recent years. Most of the late literature agrees that surgical reconstruction of the ACL is effective in improving long-term outcomes in pediatric patients, while others in the past have pleaded for non-surgical management. Our study aims to verify if ACL reconstruction (ACLR) using transphyseal technique in skeletally immature patients will provide angular deviations or growth restrictions. Retrospective cohort study; Level of evidence 4. We perfomed a retrospective study to verify if transphyseal ACLR in children with less than or equal to 2 years of remaining growth leads to either limb length discrepancies or axis deviations. Most patients who were treated using transphyseal technique showed significant improvements in their functional scores. There were statistically significant differences in lateral distal femoral angles (LDFA) and medial proximal tibial angles (MPTA), with no clinical impact. There was no significant limb length discrepancy (LLD) during the 2-year follow-up. Transphyseal ACLR is safe among children who have less than or equal to 2 years of remaining growth and brings no risk of axis deviations or limb length discrepancy.

Phantom and in vivo accuracy of frameless optical navigation in stereotactic laser interstitial thermal therapy.

Targeting accuracy presents a key factor in achieving maximal safe ablation in laser interstitial thermal therapy (LITT). The VarioGuide system has proven precise for brain biopsies, but data showing its accuracy in combination with LITT are limited. The aim of this study was to determine the phantom and in vivo accuracy of LITT probe placement using the VarioGuide system and to evaluate the effect of targeting error on maximum possible ablation volume. Stereotactic LITT probe placement was performed using the VarioGuide system in 3 phantom skulls. The same system was used in 10 patients treated with LITT, for which data were retrospectively analyzed. Target point error (TPE), target depth deviation (TDD), target lateral deviation (TLD), and angular deviation (AD) were derived from intraprocedural MRI scans of both the phantom and in vivo trajectories. In vivo, the effect of targeting error on the maximum reachable ablation was calculated as the difference between the planned maximal achievable tumor ablation (PTA) and the actual maximal achievable tumor ablation (ATA). In total, 24 phantom and 16 in vivo trajectories were analyzed. In the phantom setting, the median TPE was 3.3 mm and median AD was 1.9°. Targeting accuracy significantly decreased for longer trajectories and those less perpendicular to the skull. In patients, the authors observed a comparable median TPE of 4.0 mm but significantly higher AD of 3.2°. In vivo, targeting inaccuracy resulted in a median decrease in maximum achievable ablation volume of 6% as compared to the planned trajectory. The authors' study indicates that utilizing the VarioGuide system in combination with LITT yields an average targeting error as large as 4 mm, which was smaller for shorter and straighter trajectories. In patients, targeting inaccuracy resulted in a median 6% decrease of the planned tumor ablation volume. These are important factors that should be considered in optimal case planning and patient selection in LITT.

Guidance algorithm for reusable launch vehicle considering change in target

To address the design challenges of reentry guidance for high-speed aircraft in complex environments, and in response to the need for target adjustments during reentry, a method for designing reentry guidance laws with extended range has been introduced. The longitudinal guidance law has significantly improved real-time performance by converting infinite-dimensional optimization into a single-parameter search using the reentry flight corridor approach. The lateral guidance law employs line-of-sight angular deviation corridors to achieve target tracking, while the extended-range guidance law rapidly increases the flight distance of the reusable launch vehicle during the flight by optimizing attack angle profiles. Numerical simulations have been conducted to validate the effectiveness of the longitudinal, lateral, and extended-range guidance laws, indicating that they can meet the mission requirements for target adjustments during reentry.

Clinical-radiological results of the tibial osteotomy of valgization by internal addition in Gonarthrosis.

In knee osteoarthritis, medial-opening tibial osteotomy remains a good surgical technique, and have been effective in stabilizing and even improving osteoarthritis, Our study is about 20 cases of gonarthrosis on genu varum, treated by opening wedge valgus high tibial osteotomyconducted within the orthopedic trauma department '' B'' of the University Hospital Mohamed VI of Marrakech, over a period of 4 years. The mean age of our patients was 49 years (39-60), with a sex ratio of 1M/4F. In 55% of cases (11 cases) thegonarthrosis was related to primitive genu varum, while 45% cases (9 cases) was secondary to trauma ormeniscectomy. Clinically the knee pain was the main symptom in all cases, with an intensity level 3 on the simple verbal scale. The imagery was designed to measure angular deviations and surgical correction and monitoring the evolution. Angular deviation adjusted mean was 10.3 ° (6 ° -16 °), stages II and III of Ahlback classification, represent the mostcases of tibiofemoral osteoarthritis (90%).The filling was done by autologous bone graft, and the average degree of varus correction was 9.6 °.The results evaluated by the IKS score were excellent or good in 60% of cases for the knee score and 73% for the function score.

Association between eyeball asymmetry and offset of openings in optic nerve head canal assessed by posterior polar eyeball topography.

We investigated three-dimensional (3D) eyeball protrusion and its association with the offset between the lamina cribrosa (LC) and Bruch's membrane opening (BMO). 3D-MRI scans were taken from 93 subjects (186 eyes). An ellipsoid was fitted along the posterior 2/3 contour of each eyeball. Eyeball asymmetry with focal bulging was determined by the existence of an adjacent outward protrusion/reciprocal inward depression pair, and the angular deviation of the outermost protruded point (OPP) was measured from the nasal side of the fovea-BMO axis. The LC/BMO offset was evaluated by measuring the central retinal vascular trunk (CRVT) location from the BMO center: (1) the angular deviation and (2) the offset index as the ratio between the CRVT-BMO center distance and the BMO radius in the same direction. Seventy-nine eyes (42%) were classified as having eyeball asymmetry, which had a more superior LC/BMO offset (P < 0.001) and a larger offset index (P = 0.002). In those eyes, the angular deviation of the OPP showed a significant correlation with that of the LC/BMO offset (r = -0.724, P < 0.001), as did protrusion depth with the offset index (r = 0.291, P = 0.009). The presence of eyeball asymmetry was associated with superior LC/BMO offset (P = 0.004) and larger offset index (P = 0.009). Superior LC/BMO offset was associated with older age (P < 0.001), shorter axial length (P < 0.001) and inferior location of OPP (P < 0.001). The location and extent of focal bulging were closely associated with those of LC/BMO offset. This indicates that focal bulging during expansion might be associated with diverse directionality of LC/BMO offset.

Analyzing the dynamics of a charged rotating rigid body under constant torques

This study explores the dynamical rotary motion of a charged axisymmetric spinning rigid body (RB) under the effect of a gyrostatic moment (GM). The influence of transverse and invariable body fixed torques (IBFTs), and an electromagnetic force field, is also considered. Euler’s equations of motion (EOM) are utilized to derive the regulating system of motion for the problem in a suitable formulation. Due to the lack of torque exerted along the spin axis and the nearly symmetrical nature of the RB, the spin rate is nearly unchanged. Assuming slight angular deviations of the spin axis relative to a fixed direction in space, it is possible to derive approximate analytical solutions (AS) in closed form for the attitude, translational, and rotational movements. These concise solutions that are expressed in complex form are highly effective in analyzing the maneuvers performed by spinning RBs. The study focuses on deriving the AS for various variables including angular velocities, Euler’s angles, angular momentum, transverse displacements, transverse velocities, axial displacement, and axial velocity. The graphical simulation of the subsequently obtained solutions is presented to show their precision. Furthermore, the positive impacts that alterations in the body’s parameters have on the motion’s behavior are presented graphically. The corresponding phase plane curves, highlighting the influence of different values in relation to the electromagnetic force field, the GM, and the IBFTs are drawn to analyze the stability of the body’s motion. This study has a significant role in various scientific and engineering disciplines. Its importance lies in its ability to optimize mechanical systems, explain celestial motion, and enhance spacecraft performance.

High precision vertical angle measurement system for calibration of various angle sensors and instruments

A versatile measurement system was developed for efficient calibration of vertical angle sensors or instruments. The vertical angle measurement system (VAMS) comprises a precision rotation stage, a controller, and additional components for fixing an angle sensor or detecting angular deviation. It can generate single-axis rotation within ±120° range with a resolution of 0.01″. To detect angular deviation in angle instrument calibration, a special miniature autocollimator was developed using a diffractive optical element, providing high-precision angle measurement even with the short focal length of its lens. The performance of the VAMS was evaluated by comparing face angles of two optical polygons, measured by the VAMS and other reference systems. As typical exemplary calibrations, an electronic level and vertical angle readouts of a total station were calibrated with expanded uncertainty (k = 2) of 0.19″ and 0.51″, respectively.

Accuracy of flapless surgery using an autonomous robotic system in full-arch immediate implant restoration: A case series

ObjectivesThis observational study aimed to evaluate the accuracy of robotic computer-assisted implant surgery (r-CAIS) for full-arch immediate restoration and to analyse possible factors contributing to deviations. MethodsThree edentulous patients (five arches) underwent r-CAIS. Osteotomies were performed using an autonomous robot under the surgeon's supervision, and implant placement was performed in a freehand or robotic manner. Prefabricated provisional prostheses were delivered immediately after surgery. Postoperative cone beam computed tomography scans were performed to assess the deviations between the planned and placed implants. Statistics were compared with deviations of s-CAIS outlined in a meta-analysis. ResultsA sum of 28 implants were used. The mean global coronal and apical deviations measured 0.91 ± 0.43 mm and 1.01 ± 0.45 mm, respectively, and the mean angular deviation measured 1.21 ± 1.24 º. The r-CAIS showed significantly better precision than the s-CAIS in full-arch cases (P < 0.001). The implants inserted using the robotic arm exhibited fewer deviations than those placed in the freehand manner. Eighty percent of prefabricated provisional prostheses were successfully delivered. ConclusionsWithin the limitations of the present study, our data suggest that autonomous r-CAIS is a feasible approach for simultaneous immediate restoration in edentulous patients, showing better accuracy than s-CAIS. Further large-scale studies are necessary to verify the advantages and disadvantages of this novel technique and to explore possible factors that influence its accuracy. Clinical SignificanceAutonomous r-CAIS can provide clinically acceptable implant placement accuracy in edentulous patients, significantly surpassing s-CAIS. This level of accuracy may represent a viable therapeutic approach for simultaneous immediate full-arch restoration.

Algorithm for correction of geometric distortions of spectral images recorded using an acousto-optical hyperspectrometer under conditions of angular deviations

Algorithm for correction of geometric distortions of spectral images recorded using an acousto-optical hyperspectrometer under conditions of angular deviations

Accuracy of template-based guided dental implant placement-An invitro comparison of different manufacturingmethods.

This study investigates effects of surgical guide manufacturing process on 3D transfer accuracy of planned dental implant position, using three production methods: additive 3D-printed (3DF), subtractive milled (MF), and analog laboratory fabricated templates (LF). Implant position for a single-tooth gap (#26) planned digitally. 3DF and MF templates were designed digitally, while LF templates were analogously created. For each manufacturing type, 10 surgical guides were fabricated. Each guide was used for template-guided implant placement in model replicas. For evaluation of implant placement, cone beam computed tomography scans of all implanted models were superimposed, and implant positions were determined. Deviations at implant shoulder/apex were measured, and median and inter-quartile range (IQR) were determined for mesio-distal, oro-facial, coronal apico, 3D spaces, and angles. At implant shoulder, vertical components dominated position deviations (up to 1.04 mm, IQR 0.28 mm for 3DF). Horizontal deviations were much lower (mesio-distally up to 0.38 mm, IQR 0.36 mm (LF)). Implant apex shows similar vertical deviations, while horizontal deviations clearly increased compared to shoulder, especially in mesio-distal direction. Median angular deviations were between 2.1° (IQR 2.0 mm, max. 4.2°) for 3DF and 3.3° (IQR 1.9 mm, max. 5.3°) for MF. No statistical differences were found between manufacturing types (Kruskal-Wallis test, p = .05). The study showed the method of implant guide fabrication did not affect the accuracy of implant placement within the limits of an invitro environment. All methods resulted in implant placement which did not exceed the accepted safety deviation envelope (1.5-2.0 mm).

Does a novel 3D printed individualized guiding template based on cutaneous fiducial markers contribute to accurate percutaneous insertion of pelvic screws? A preliminary phantom and cadaver study

BackgroundMost 3D-printed guiding templates require dissection of soft tissues to match the corresponding surfaces of the guiding templates. This study sought to explore the accuracy and acceptability of the novel 3D printed individualized guiding templates based on cutaneous fiducial markers in minimally invasive screw placement for pelvic fractures.MethodsThe printed template was tested on five high-fidelity biomimetic phantom models of the bony pelvis and its surrounding soft tissues as well as on two fresh frozen cadavers. Four cutaneous fiducial markers were transfixed on each phantom model prior to performing CT scans to reconstruct their 3D models. Personalized templates for guiding screw insertion were designed based on the positions of the fiducial markers and virtually planned target screw channels after scanning, followed by 3D printing of the guide. Phase 1 consisted of five expert surgeons inserting one anterograde supra-pubic screw and one sacroiliac screw percutaneously into each phantom model using the 3D-printed guide. The deviation of screw positions between the pre-operative planned and post-operative actual ones was measured after registering their 3D modelling. A Likert scale questionnaire was completed by the expert surgeons to assess their satisfaction and acceptability with the guiding template. Phase 2 consisted of repeating the same procedures on the fresh frozen cadavers in order to demonstrate face, content and concurrent validity.ResultsIn Phase 1, all ten screws were successfully implanted with the assistance of the guiding template. Postoperative CT scans confirmed that all screws were safely positioned within the bony pelvic channels without breaching the far cortex. The mean longitudinal deviation at the bony entry point and screw tip between the pre-operative planned and post-operative actual screw paths were 2.83 ± 0.60 mm and 3.12 ± 0.81 mm respectively, with a mean angular deviation of 1.25 ± 0.41°. Results from the Likert questionnaire indicated a high level of satisfaction for using the guiding template among surgeons. In Phase 2, results were similar to those in Phase 1.ConclusionsThe 3D-printed guiding template based on cutaneous fiducial markers shows potential for assisting in the accurate insertion of percutaneous screws in the pelvis.

Damage evaluation of the austenitic heat-resistance steel subjected to creep by using Kikuchi pattern parameters

Abstract Austenitic heat-resistance steel is widely employed in ultra-supercritical power generation because of its superior performance. This article reports the evaluation of creep damage of a typical Super304H austenitic heat-resistance steel by using the Kikuchi pattern parameters, such as band contrast (BC), mean angular deviation (MAD), and band slope (BS). It was found that the mean BC and MAD values did not show a monotonic changing trend and then an in-depth research that distinguished grain boundary and grain interior regions of Super304H steel was studied, respectively. The results manifested that, with the increase of creep time, both the mean BC and BS values showed a monotonic decreasing trend, while the MAD did not. Besides, compared with the BC, the change amplitude of BS was larger. The results indicate that the BS could be a useful indicator, which can be utilized to evaluate the creep degree of Super304H steel in a quantitative way.

Effect of using scan body accessories and inter-implant distances on the accuracy of complete arch implant digital impressions: An in vitro study.

To introduce a novel design for scan body accessory parts that are reusable, easy to attach and detach without permanent change of the scan body, and can be used with different inter-implant distances to enhance the accuracy of complete arch implant scans. A maxillary polymethylmethacrylate (PMMA) model with a soft tissue replica was fabricated with four implant analogs located at tooth positions 17, 13, 22, and 27 with 18, 25, and 30mm inter-implant distances. Four scan bodies (SBs) were attached to the implants. The model was scanned with a laboratory scanner to be used as a reference scan. A total of 40 scans were made with the same intraoral scanner and they were divided equally into two groups. Group A: Complete arch implant scans without scan body accessories (n = 20), and Group B: Complete arch implant scans with scan body accessories (n = 20). Intraoral scans were exported and superimposed on the reference scan using reverse engineering inspection software to be evaluated for 3D deviations, angular deviations, and linear deviations. Statistical analysis was performed with student t-test and analysis of variance (ANOVA) with repeated measures followed by post hoc adjusted Bonferroni test. The level of significance was set at P = 0.05. The scan body accessories decreased both the 3D and linear deviations, with a statistically significant difference at SB4 for the 3D deviation (P = 0.043) and the linear inter-implant discrepancies between SB1-SB2 and SB3-SB4 (P = 0.029 and < 0.001), respectively. However, there was no statistically significant difference in angular deviation between the study groups. Implant positions had significant differences within each group. A significant improvement in the accuracy of the complete arch implant digital impression was achieved by using the scan body accessories, particularly in reducing the 3D and linear deviations at the most distant implant positions.

Accuracy of open-sleeved vs. closed-sleeved static computer-assisted implant systems in immediate maxillary molar implant placement: An invitro study.

The objective of this study is (1) to compare the accuracy of an open-sleeved static computer-assisted implant system (sCAIS) with a closed-sleeve sCAIS and free-hand approach in immediate implant placement (IIP) of maxillary molar sites and (2) to investigate the influence of socket morphology on these approaches. Ninety partially edentulous duplicated maxillary models simulating three different molar sockets (type A, B, and C based on Smith and Tarnow's classification) were investigated. Three modalities, including sCAIS with open-sleeves, sCAIS with closed-sleeves, and free-hand approach, were applied separately to 30 models with 120 sockets. A customized Python script automatically measured the deviations between the virtual and actual implant positions for all 360 implants. The 3D deviations of sCAIS were significantly influenced by the socket and sleeve types. Both guided groups exhibited significantly less deviation than the free-hand approach. Type A and C sockets resulted in better implant positions than type B socket sites. In type B sockets, the open-sleeve group achieved significantly less deviation compared to the closed-sleeve group, with respect to apical global (1.34 ± 0.53 vs. 1.84 ± 0.59 mm), coronal horizontal (0.68 ± 0.36 vs. 0.93 ± 0.34 mm), apical horizontal (1.21 ± 0.59 vs. 1.74 ± 0.63 mm), and angular (3.30 ± 1.41 vs. 4.41 ± 1.96°) deviations. Guided implant surgery significantly reduces deviations during molar IIP compared to free-hand procedures. Furthermore, the use of open-sleeve sCAIS appears to be more effective in minimizing deviations in type B sockets when compared with the closed-sleeve guided system.

Influence of augmented reality technique on the accuracy of autotransplanted teeth in surgically created sockets

BackgroundThe objective of the present study was to evaluate the reliability of an augmented reality drilling approach and a freehand drilling technique for the autotransplantation of single-rooted teeth. Materials and methodsForty samples were assigned to the following surgical techniques for drilling guidance of the artificial sockets: A. augmented reality technique (AR) (n = 20) and B. conventional free-hand technique (FT) (n = 20). Then, two models with 10 teeth each were submitted to a preoperative cone-beam computed tomography (CBCT) scan and a digital impression by a 3D intraoral scan. Afterwards, the autotrasplanted teeth were planned in a 3D dental implant planning software and transferred to the augmented reality device. Then, a postoperative CBCT scan was performed. Data sets from postoperative CBCT scans were aligned to the planning in the 3D implant planning software to analize the coronal, apical and angular deviations. Student’s t-test and Mann–Whitney non-parametric statistical analysis were used to analyze the results.ResultsNo statistically significant differences were shown at coronal (p = 0.123) and angular (p = 0.340) level; however, apical deviations between AR and FT study groups (p = 0.008) were statistically significant different.ConclusionThe augmented reality appliance provides higher accuracy in the positioning of single-root autotransplanted teeth compared to the conventional free-hand technique.