Position Of Implants Research Articles

The Precision of All-on-Four Implant Position Recorded from Three Different CBCT Machines.

To investigate the dimensional discrepancy and degree of deviation of All-on-Four implant position between different cone-beam computed tomography (CBCT) machines. Four implants (4.5 × 10 mm Superline II, Dentium, South Korea) were placed in an All-on-Four style in an artificial mandible. The jaw was radiated 30 times using three different CBCT machines (Rainbow CT, Dentium; Veraview X800, Morita, Japan; Planmeca Viso G3, Planmeca OY, Finland). A total of 30 Digital Imaging and Communications in Medicine (DICOM) files were exported, n = 10. All-on-Four implants from each DICOM file were segmented and exported as an STL file (three-dimensional image) using Blue Sky Plan software (version 4.12.13/Blue Sky Bio, United States). All-on-Four implant zone dimensions (X, Y, and Z axes) and the total degree of deviation between All-on-Four implants per CBCT machine were measured using Autodesk Meshmixer software (version 3.5.474/California, United States). The data distribution's normality and variances' equality were tested with Shapiro-Wilk's and Levene's tests, respectively (p-value < 0.05). Data were analyzed using Brown-Forsythe one-way analysis of variance and Tamhane's post hoc tests to compare the differences between the groups (p-value <0.05). The respective X, Y, and Z mean dimensions of the All-on-Four implant zone were: Dentium (34.95, 14.71, and 9.97); Morita (34.88, 14.74, and 10.56); and Planmeca (34.73, 15.15, and 12.33). Significant differences between CBCT machines were found in all axes (p-value < 0.05); however, the Z-axis had the most differences. Notably, Planmeca exhibited the highest standard deviation (SD) in all axes (0.16-0.35), exhibiting the lowest consistency in the CBCT machines' readings. The Dentium exhibited the lowest deviation in the implant position, with the lowest SD (0.61). A significant difference in the total degree of deviation was spotted when only Morita was included in the comparison (p-value < 0.05). This study's findings are of significant importance as they reveal that the implant position recorded from the CBCT machines was most discrepant in the buccolingual dimension (Z-axis). Planmeca exhibited the least implant-dimensional accuracy of the CBCT machines, while Dentium exhibited the highest implant position accuracy. These results could significantly impact the choice of CBCT machine for implant placement, especially since an accurate CBCT image is crucial for digital implant planning.

Is immediate dental implant in fibula free flap beneficial for implant survival and osteoradionecrosis in jaw reconstruction?

ObjectivesThis study aimed to compare the risk of osteoradionecrosis and implant survival in oral cancer patients undergoing immediate dental implants during jaw reconstruction, termed “Jaw in a Day” (JIAD), with those receiving no implants or delayed implants (non-JIAD). Patients & methodsClinicopathologic data were collected from prospectively enrolled JIAD patients (n = 10, 29 implants) and retrospectively from non-JIAD patients (n = 117, 86 implants). Survival analyses were performed to assess implant survival and osteoradionecrosis-free survival. ResultsOsteoradionecrosis occurred in 0 % of JIAD cases compared to 19.3 % in non-JIAD cases without implants and 71.4 % in non-JIAD cases with delayed implants (p = 0.008). Osteoradionecrosis-free survival was significantly better in the JIAD group than the non-JIAD group (p = 0.0059). Implants in the JIAD group all survived regardless of radiation therapy (29/29, 100 %) and 95.1 % (58/61) of implants survived in delayed implants in non-irradiated fibula without radiotherapy. Meanwhile, only 11 of 25 implants placed in irradiated fibula flaps survived, even when the implants were placed after a median time interval of 624 days after radiotherapy, and none of them were earlier than 360 days. The survival analysis revealed a significant difference (p < 0.0001). ConclusionJIAD appears to offer superior outcomes in terms of implant survival and osteoradionecrosis prevention compared to delayed implant placement. Placing implants in irradiated fibula, even after years, significantly poses high risk of implant failure and osteoradionecrosis. JIAD represents a promising approach for optimal rehabilitation, particularly in oral cancer patients requiring postoperative radiotherapy. Proper positioning and orientation of implants and flaps are crucial for implant survival.

High delta angle after reverse total shoulder arthroplasty increases stresses of the acromion: biomechanical study of different implant positions

BackgroundAcromial fractures after Reverse Total Shoulder Arthroplasty (RTSA) are a common complication. Nevertheless, only a few studies have identified risk factors for acromial fractures after RTSA. High delta angle (combination of inferiorization and medialization of the center of rotation) after RTSA was identified as a risk factor in recent studies. The aim of this study was the biomechanical exploration of different delta angles and implant configurations with regard to the acromial stress. MethodsIn a rigid body model of the upper extremity muscle, forces of the deltoid muscle were calculated before and after implanting RTSA in different arm and implant positions. The deltoid muscle was divided into an anterior, middle, and posterior part. Implant positions of the glenoid components were changed in the medialization, lateralization and inferiorization of the center of rotation (COR) as well as lateralization of the humeral component. Further, in a finite element model of the upper extremity, the stresses of the acromion in the same implant design configurations were measured. ResultsDifferences in acromial stress between different delta angle model configurations were observed. Lateralization (5 mm, 10 mm) of the glenosphere reduced maximal acromial stress by 21% (1.5 MPa) and 31% (1.3 MPa), respectively. Inferiorization (5 mm, 10 mm) of the glenosphere increased maximal acromial stress by 5% (2.0 MPa) and 15% (2.2MPa), respectively. Changes in positioning the humeral component was found to have the highest impact in this model configuration. A 10 mm lateralized humeral component reduced acromial stress by 37% (1.2 MPa) while in the 6 mm medialized configuration, an increase in acromial stress by 83% (3.48 MPa) was observed. There was a high correlation between delta angle and acromial stress (R-squared = 0.967). ConclusionImplant design configuration has an impact on the acromial stress. High delta angles correlate with an increase in acromial stress. Both lateralization of the COR and the humerus decreased the acromial stress in our study. The lateralization of the humerus has the highest impact in influencing acromial stress. Due to contrary results in the current literature, further studies with focus on the acromial stress influenced by different anatomical variants of the shoulder and the acromion are needed before a clinical recommendation can be made.

Impact of implant positions in total knee arthroplasty on the postoperative knee kinematics of tibial rotation

IntroductionIn total knee arthroplasty (TKA), the implant positions and knee kinematics, as well as the manifestation of medial pivot motion, play pivotal roles in determining postoperative clinical outcomes. The purpose of the current study was to analyze the correlation between knee kinematics, which was measured during TKA and implant positions derived using computed tomography (CT) examination after TKA. MethodsThis study comprised 64 patients (76 knees) who underwent primary TKA between 2015 and 2022. A navigation system was used in TKA procedures, and intraoperative knee kinematics were automatically calculated with it. Utilizing three-dimensional evaluation software, positioning of implants was quantified with CT images taken pre- and post-operatively. Multiple regression analyses were employed to explore the impact of femoral component position (FP) and tibial component position (TP) on knee kinematics, focusing on the extent of tibial rotational motion (TRM) during passive knee motion. ResultsFP affected TRM between knee extension and 90° flexion (p = 0.003, 95 % confidence interval [CI]: 0.315–1.384) and between knee extension and full flexion (p = 0.0002, 95 % CI: 0.654–1.844) after TKA. FP in internal rotation positively affected internal TRM after TKA. TP was not associated with TRM. ConclusionsFindings of the current study suggest that FP in internal rotation positively impacts knee kinematics after TKA.

Impact of Different Valve-in-Valve Positions on Functional Results of the New Generation of Balloon-Expandable Transcatheter Heart Valve.

Very precise positioning of the transcatheter heart valve (THV) inside the degenerated SAV is a crucial factor for valve-in-valve (ViV) procedure to achieve optimal hemodynamic results. Therefore, our study aimed to investigate the impact of implantation depth on functional results after ViV procedures in a standardized in vitro setting. THV (SAPIEN 3 Ultra 23-mm size) and three SAV models (Magna Ease, Trifecta, and Hancock II-all 21-mm size) were tested at different circulatory conditions in five different positions of the THV (2-6 mm) inside the SAV. Mean pressure gradient (MPG), effective orifice area (EOA), geometric orifice area (GOAmax), and pinwheeling index (PWImean) were analyzed. EOA and MPG of the THV did not differ significantly regarding the position inside the Magna Ease and the Hancock II (p > 0.05). However, EOA differed significantly, depending on the position of the THV inside Trifecta (2 vs. 5 mm; p = 0.021 and 2 vs. 6 mm; p < 0.001). The THV presented the highest EOA (2.047 cm2) and the lowest MPG (5.387 mm Hg) inside the Magna Ease, whereas the lowest EOA (1.335 cm2) and the highest MPG (11.876 mm Hg) were shown inside the Hancock II. Additionally, the highest GOAmax and the lowest PWImean of the THV were noticed inside the Magna Ease. The THV showed lower GOAmax and higher PWImean inside the Trifecta when placed in a deeper position. Deep implantation of the SAPIEN 3 Ultra inside the Trifecta correlates with impaired functional results. In contrast, the implantation position of the SAPIEN 3 Ultra inside the Magna Ease and the Hancock II did not have a significant effect on functional results.

Deep learning-based approach for 3D bone segmentation and prediction of missing tooth region for dental implant planning

Recent studies have shown that dental implants have high long-term survival rates, indicating their effectiveness compared to other treatments. However, there is still a concern regarding treatment failure. Deep learning methods, specifically U-Net models, have been effectively applied to analyze medical and dental images. This study aims to utilize U-Net models to segment bone in regions where teeth are missing in cone-beam computerized tomography (CBCT) scans and predict the positions of implants. The proposed models were applied to a CBCT dataset of Taibah University Dental Hospital (TUDH) patients between 2018 and 2023. They were evaluated using different performance metrics and validated by a domain expert. The experimental results demonstrated outstanding performance in terms of dice, precision, and recall for bone segmentation (0.93, 0.94, and 0.93, respectively) with a low volume error (0.01). The proposed models offer promising automated dental implant planning for dental implantologists.

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.

Comparison of range of motion between 2-year clinical outcomes and predictions of a static scapula preoperative planning software for reverse shoulder arthroplasty

BackgroundPreoperative planning has gained popularity in the management of reverse shoulder arthroplasty (RSA). Commercially available software provides 3-dimensional segmentation of scapula and humerus, as well as providing arc of motion for the implanted articulation and identifying potential areas of bony impingement. However, these software algorithms use a fixed scapula model, disregarding the preoperative clinical range of motion (C-ROM) of the patient, be it glenohumeral or scapulothoracic, as well as any soft tissue parameters. This study aims to compare the ROM based on preoperative planning software by using the implant position from postoperative computed tomography (CT) images (predicted ROM using preoperative planning software [P-ROM]), with the C-ROM assessed at minimum of 2 years of follow-up. MethodsPreoperative and postoperative CT scans of 46 patients who underwent primary RSA between 2017 and 2021 were analyzed. At the postoperative 2-year review, each patient was assessed for active ROM. Implant size and position based on operative notes and postoperative CT scans were used to replicate the performed surgery in the planning software. Abduction, flexion, and external rotation motion were simulated and recorded. The relationship between C-ROM and P-ROM was investigated using linear regression analysis, Pearson correlation coefficient, and paired t-test. ResultsP-ROM was significantly lower than C-ROM at 2 years postoperatively (P < .001), with an average discrepancy of 78° in abduction, 47° in flexion, and 37° in external rotation (C-ROM: abduction 155° ± 21° [80°-180°]; flexion 160° ± 17° [90°-180°]; external rotation 52° ± 14° [10°-80°] vs. P-ROM: abduction 77° ± 13° [53°-107°]; flexion 112° ± 25° [67°-180°]; external rotation 15° ± 21° [0°-79°]). The linear regression analysis indicated weak agreement between C-ROM and P-ROM (abduction R2 = 0.03; flexion R2 = 0.01; external rotation R2 = 0.04). Pearson’s correlation coefficients revealed weak correlations of −0.18, 0.03, and 0.21 for abduction, flexion, and external rotation, respectively. ConclusionP-ROM based on preoperative software in its current form does not allow the prediction of the C-ROM at 2 years of follow-up for patients undergoing RSA.

Reliability and accuracy of intraoperative fluoroscopy assessment of acetabular cup anteversion in supine direct anterior approach total hip arthroplasty

Poor implantation positioning of hip prostheses is considered the primary factor affecting postoperative joint wear. Cup anteversion in direct anterior approach (DAA) total hip arthroplasty (THA) is often excessive. Intraoperative fluoroscopy (IF) are effective for improving implant placement accuracy. This study aimed to analyze IF’s reliability and accuracy in assessing intraoperative anteversion. Sixty-two consecutive hips underwent primary THA utilizing DAA alongside IF for cup placement. Intraoperative anteversion was measured using IF images, while postoperative CT and standard anteroposterior (AP) radiographs were used to calculate true anteversion component angles. Differences and correlations between intraoperative and true anteversions were analyzed, and intraclass correlation coefficients (ICC) determined the inter- and intra-observer reliabilities. Excellent intra- and inter-observer reliabilities were observed for all radiographic and CT methods (ICC > 0.9). Strong correlations (PCC > 0.6) existed between anteversion measured on IF image and postoperative CT and AP pelvic measurements. Intraoperative anteversion measured on IF images (16.8 ± 3.2°) was smaller than anteversion measured postoperatively on AP X-rays (21.3 ± 4.7°, P < 0.001) and CT (22.0 ± 4.9°, P < 0.001), with average differences of 4.5°and 5.3°, respectively. Under several influencing factors, the accuracy of IF in assessing cup anteversion in DAA-THA may be limited. However, this still requires large-sample experiments for verification.

In vivo study of a novel 3D-printed motion-preservation artificial cervical corpectomy construct: short-term imaging and biocompatibility evaluations in a goat model

BackgroundNonfusion technologies, such as motion-preservation devices, have begun a new era of treatment options in spine surgery. Motion-preservation approaches mainly include total disc replacement for anterior cervical discectomy and fusion. However, for multisegment fusion, such as anterior cervical corpectomy and fusion, the options are more limited. Therefore, we designed a novel 3D-printed motion-preservation artificial cervical corpectomy construct (ACCC) for multisegment fusion. The aim of this study was to explore the feasibility of ACCC in a goat model.MethodsGoats were treated with anterior C3 corpectomy and ACCC implantation and randomly divided into two groups evaluated at 3 or 6 months. Radiography, 3D CT reconstruction and MRI evaluations were performed. Biocompatibility was evaluated using micro-CT and histology.ResultsPostoperatively, all goats were in good condition, with free neck movement. Implant positioning was optimal. The relationship between facet joints was stable. The range of motion of the C2-C4 segments during flexion–extension at 3 and 6 months postoperatively was 7.8° and 7.3°, respectively. The implants were wrapped by new bone tissue, which had grown into the porous structure. Cartilage tissue, ossification centres, new blood vessels, and bone mineralization were observed at the porous metal vertebrae-bone interface and in the metal pores.ConclusionsThe ACCC provided stabilization while preserving the motion of the functional spinal unit and promoting bone regeneration and vascularization. In this study, the ACCC was used for anterior cervical corpectomy and fusion (ACCF) in a goat model. We hope that this study will propel further research of motion-preservation devices.

Association between socioeconomic position and discontinuation of pharmacotherapy for heart failure after cardiac resynchronization therapy.

Pharmacological therapy remains a cornerstone in heart failure (HF) treatment despite implantation of a cardiac resynchronization therapy (CRT) device. The aim of this study was to investigate the association between 1) drug discontinuation, and 2) long-term adherence to HF pharmacotherapy after CRT implantation and socioeconomic position and multimorbidity. We conducted a registry-based cohort study including all patients who underwent a first-time CRT implantation at Aarhus University Hospital from 2000-2017. HF pharmacotherapy included beta blockers (BBs), renin angiotensin system inhibitors (ACEI/ARB), and mineralocorticoid receptor antagonists (MRAs). Patients were identified using the Danish Pacemaker and ICD Registry, and information about medication and comorbidities was obtained through linkage to the Danish health registries. We identified 2,007 patients of whom 1,880 (94%) were eligible for inclusion. The cumulative incidence of drug discontinuation at 10 years was 6% (95% confidence interval [CI] 5-8%) for BB, 10% (95% CI 9-12%) for ACEI/ARB, and 24% (95% CI 20-27%) for MRAs. Living alone was associated with higher BB discontinuation rates (hazard ratio [HR] 1.83, 95%CI 1.20-2.79), whereas patients with multimorbidity were more likely to discontinue ACEI/ARB- (HR 1.92, 95%CI 1.33-2.80) and MRA therapy (HR 1.51, 95% CI 1.10-2.09). Income- and educational level did not influence drug discontinuation rates, and similar adherence patterns were observed across all strata of socioeconomic position and multimorbidity. In patients with CRTs, drug discontinuation rates were low, and adherence to HF pharmacotherapy was comparable regardless of socioeconomic position. Living alone and multimorbidity were associated with discontinuation of specific HF drugs.

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.

Analysis of the correlation between peri-implant probing depth and radiographic bone level

Objective: To evaluate the correlation between peri-implant probing depth (PPD) and radiographic bone level (rBL) in implants with peri-implantitis. Methods: From January 2019 to December 2022, 24 patients with 30 implants who suffered from peri-implantitis at the Department of Periodontology, Peking University School and Hospital of Stomatology were included in the present research. SPSS 26.0 software was used to simple random sampling select 30 healthy implants from which with electronic examination records in Department of Periodontology, Peking University School and Hospital of Stomatology from January 2007 to June 2023 as the control group. On the premise of retaining the implant prosthesis, PPD (distance between pocket bottom and peri-implant soft tissue margin) was examined using a Williams periodontal probe with a light force (about 0.2 N), and a total of 4 sites were recorded for each implant. Periapical radiography and cone beam CT were applied to measure the rBL (distance between the reference point at the neck of the implant and the apical point of the bone defect) and the width of the bone defect (DW), and the type of the bone defect was recorded. The correlation and consistency between the diagnosis of PPD and rBL were analyzed. Results: PPD was significantly correlated with rBL in a total of 60 implants in 180 sites (r=0.64, P<0.001). The chi-square test showed an 8.15-fold increase in the detection rate of PD≥6 mm at sites with rBL≥1 mm (P<0.001). Multivariate logistic regression analysis showed that rBL was still statistically associated with PPD after adjustment for jaw position and examination position of implants. Take rBL <1 mm as reference, the odds ratios (OR) of 1 mm≤rBL<2 mm, 2 mm≤rBL<3 mm and rBL≥3 mm group with PPD were 6.23 (P=0.014), 2.77 (P=0.183) and 10.87 (P=0.001), respectively. Conclusions: There is a positive correlation between PPD and rBL in implants with peri-implantitis. PPD can be used as a clinical examination index to assist in estimating the level of peri-implant bone under the premise of retaining the prosthesis.

Enhancing robotic precision in medial UKA: Image-based robot-assisted system had higher accuracy in implant positioning than imageless robot-assisted system across 292 knees.

The objective of this study was to compare the degree of accuracy in implant positioning and limb alignment offered by two robot-assisted (RA) systems: an image-based robot-assisted (IBRA) versus an imageless robot-assisted (ILRA) system for the treatment of medial knee osteoarthritis with unicompartmental knee arthroplasty (UKA). This retrospective radiographic study included medial UKAs performed between 2011 and 2023. Radiographic measurements taken preoperatively and at 1-year postoperative control visit focusing on hip-knee-ankle angle (HKA), posterior tibial slope (PTS), tibial component coronal alignment relative to Cartier's angle and restoration of proper joint line (JL) height were analyzed. Outliers for postoperative measurements were defined as follows: HKA <175° or >180°, PTS <2° or >8°, >3° or <-3° alterations in Cartier's angle and ±2 mm changes in the height of the joint line. The final sample consisted of 292 medial UKAs: 95 (32.5%) with an IBRA system and 197 (67.5%) with an ILRA system. Implant positioning and limb alignment were more accurate in the group of patients treated with IBRA, HKA (77.9% vs. 67.5%, p = 0.07), PTS (93.7% vs. 82.7%, p = 0.01), restoration of tibial varus relative to Cartier's angle (87.4% vs. 65%, p < 0.001) and restoration of JL height (81.1% vs. 69.5%, p = 0.04). Medial UKA surgery using an IBRA system was associated with a higher degree of accuracy in implant positioning and postoperative limb alignment as compared to an ILRA system. This is a valuable contribution to help communicate the advantages of using this surgical technique and improve its reproducibility. Level III, Retrospective cohort study.

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).

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.

A Retrospective Study to Compare Patient Outcomes from Standard Total Knee Arthroplasty (TKA) versus Navigation-Guided Arthroplasty Using the Brainlab Software-Guided Surgical System at a Center in Hebei Province January 2021 to July 2023.

BACKGROUND This retrospective study aimed to compare patient outcomes from standard total knee arthroplasty (TKA) vs navigation-guided arthroplasty using the Brainlab software-guided surgical system at Cangzhou Hospital of Integrated TCM-WM, Hebei, Hebei Province, China from January 2021 to July 2023. MATERIAL AND METHODS A total of 239 patients who underwent total knee arthroplasty in Cangzhou Hospital of Integrated TCM-WM, Hebei from January 2021 to July 2023 were retrospectively analyzed. According to the inclusion criteria, 212 eligible patients were selected for analysis and divided into a Navigation Group (NG) (n=105) and a Traditional Group (TG) (n=107) according to surgical method used. Outcomes measured included duration of disease, operative time, intraoperative blood loss volume, postoperative length of hospital stay, and pain measured by the hospital for special surgery knee score (HSS), Western Ontario and McMaster University Osteoarthritis Index (WOMAC), and forgotten joint score (FJS). RESULTS The comparison of perioperative results between the 2 groups showed that the incision length in the NG was significantly longer than that in the TG (P<0.001, 95% Cl 2.59-3.35). At 3 months after surgery, the HSS score of the NG was statistically higher than that of the TG (P=0.002, 95% Cl 3.42-4.46); the WOMAC score of the NG was lower than that of the TG (P<0.001, 95% Cl -4.41-2.87); and the FJS score of the NG was significantly higher than that of the TG (P=0.003, 95% Cl 2.39-3.67). CONCLUSIONS Compared with conventional TKA, use of the Brainlab navigation system is associated with a longer incision, more accurate implantation position of the prosthesis, faster recovery of knee joint function, and helps patients to "forget" about their knee prosthesis in the short term.

A comparative evaluation of masticatory load distribution in different types of prosthesis with varying number of implants: A FEM analysis

AimTo identify the optimal number and position of implants to reduce stress concentration on the implant, denture, and attachment system for sustaining an overdenture prosthesis. Materials and methodsBy incorporating one to eight indigenous implants with bar-type attachments, eight 3D finite element models of mandibular overdentures were created. All models received a 200 N vertical load, and the biomechanical characteristics of peri-implant bone were assessed. ResultThe study observed that with a vertical load of 200 N, the maximum equivalent stress around peri-implant tissue in all models was within the physiological tolerance threshold of bone. The von Mises stress values ranged from 116.18 MPa to 536.7 MPa. ConclusionThe three-implant-supported overdenture model revealed superior peri-implant stress, stability, cost-effectiveness, and hygiene maintenance outcomes. Placing a third implant in the mid-symphysis region may offer a practical solution to reduce rotations in two-implant-supported overdentures.

Dental Implant Positioning Accuracy Using a Key or Keyless Static Fully Guided Surgical System: A Prospective Systematic Review and Meta-analysis.

To realize a systematic review with prospective meta-analysis aiming to compare the accuracy of static fully guided implant placement depending on the drill key modality (conventional drill key surgery systems vs newer keyless systems) and evaluate the impact of deviation factors. An electronic systematic search was conducted to identify prospective clinical trials matching inclusion criteria. The variables of interest were coronal global, apical, vertical, and angular deviations. The types of edentulism and surgical guide support were investigated as deviation factors. Meta-regression (mixed-effect model) was performed. Heterogeneity was assessed using Cochrane's I. test and interpretation thresholds. A total of 1,233 implants in 475 patients were analyzed (18 studies included). Coronal global deviation was significantly lower in the keyless group than in the key group (-0.36 mm; 95% CI -0.62, -0.09; P = .008). Angulation control of the keyless system was superior to that of the key system (-0.36 degrees; 95% CI -0.75, 0.02; P = .063). Nonsignificant differences were found between both groups in apical (P = .684) and vertical deviations (P = .958). Significant influence of the type of edentulism (single, partial, total) and surgical guide support (tooth, mucosa, bone) on the overall amount of coronal global, apical, and angular deviations was found (P < .001). The lowest deviations were found in partial edentulism and tooth-supported surgical guide groups. (P < .001). Keyless static fully guided surgical systems allowed significantly better control of coronal and angular deviations than conventional systems. The types of edentulism and surgical guide support seemed to influence the positioning accuracy.

Stress Transmission on Bone and Prosthetic Screws Influenced by Implant Position: A Finite Element Analysis

Stress Transmission on Bone and Prosthetic Screws Influenced by Implant Position: A Finite Element Analysis