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An implant’s thread design plays a key role in enhancing primary stability by optimising the distribution of loading forces and biomechanical structural interlocking. An increase in bone-to-implant contact (BIC) surface availability affects osseointegration timing and leads to different biomechanical behaviours. To assess their theoretical impacts on osseointegration functionality, this study aims to analyse and compare the surface areas of two different thread designs: progressive knife-edge and V-shaped metric ISO ones. Six implant models are virtually created, with progressive knife-edge threads, non-self-tapping ISO threads, and ISO threads with tapping areas, considering two arbitrary diameters (3.8 mm and 4.6 mm). For both diameters, the models also have identical lengths (9.5 mm) and external outlines. The total, superior half, and inferior half external surface areas are measured using a digital tool (SolidWorks 2023 SP 5.0, Dassault Systèmes, Waltham, MA, USA). Then, the percentage difference in external surface area (ΔESA) is calculated. A greater ΔESA is found in the knife-edge design compared to the ISO thread self-tapping implants for the 4.6 mm diameter (ΔESA = +9.9%). However, for the 3.8 mm diameter, the ΔESA is −1.5% in favour of the ISO self-tapping model. Considering the apical half of the models, the ΔESA is always greater in the knife-edge models, varying from +9.3% to +23.5%. Implants with progressive knife-edge threads offer a significantly larger external surface area than those with ISO threads for the 4.6 mm rather than the 3.8 mm diameter. Considering the apical halves of the implants, the tapping area negatively affects the ΔESA, as well as the ISO thread design. Future research is needed to investigate whether the inspected surface area differences correspond to significant primary and secondary stability variations.

Objective To assess the efficacy of three mechanical decontamination methods in four types of commercially available implants. Material and methods Ninety-six implants of four commercial brands with different designs (regarding thread depth and thread pitch) were soaked in a surrogate biofilm (ink) and air-dried. Circumferential standardized peri-implant defects with 6 mm in depth and 1.55 mm in width were custom-made with a 3D printer. Stained implants were inserted in the defects and instrumented with three different methods: a titanium brush (TNB), a metallic ultrasonic tip (IST) and an air abrasive (PF). Standardized photographs were taken vertically to the implant axis (flat view), and with angulations of 60° (upper view) and 120° (lower view) to the implant long axis. The percentage of residual stain (PRS) was calculated with the image analysis software. Scanning electron microscope evaluations were performed on the buccal aspect of the implants at the central level of the defect. Results The efficacy of PF was significantly inferior to the TNB and IST in all implant designs, while there were no significant differences between TNB and IST. IST showed significantly higher PRS in the implant with the highest thread pitch, while the TNB had the highest PRS in the implant with a marked reverse buttress-thread design. The micro-thread design had the lowest values of PRS for all decontamination methods. The apically facing threads represented the areas with highest PRS for all implant designs and decontamination methods. Conclusion Thread geometry influenced the access of the decontamination devices and in turn its efficacy. Implants with lower thread pitch and thread depth values appeared to have less residual staining. Clinical relevance Clinicians must be aware of the importance of thread geometry in the decontamination efficacy.

Purpose The macrogeometry of a dental implant plays a decisive role in its primary stability. A larger diameter, a conical shape, and a roughened surface increase the contact area of the implant with the surrounding bone and thus improve primary stability. This is considered the basis for successful implant osseointegration that different factors, such as implant design, can influence. This narrative review aims to critically review macro-geometric features affecting the primary stability of dental implants. Methods For this review, a comprehensive literature search and review of relevant studies was conducted based on formulating a research question, searching the literature using keywords and electronic databases such as PubMed, Embase, and Cochrane Library to search for relevant studies. These studies were screened and selected, the study quality was assessed, data were extracted, the results were summarized, and conclusions were drawn. Results The macrogeometry of a dental implant includes its surface characteristics, size, and shape, all of which play a critical role in its primary stability. At the time of placement, the initial stability of an implant is determined by its contact area with the surrounding bone. Larger diameter and a conical shape of an implant result in a larger contact area and better primary stability. But the linear relationship between implant length and primary stability ends at 12 mm. Conclusions Several factors must be considered when choosing the ideal implant geometry, including local factors such as the condition of the bone and soft tissues at the implant site and systemic and patient-specific factors such as osteoporosis, diabetes, or autoimmune diseases. These factors can affect the success of the implant procedure and the long-term stability of an implant. By considering these factors, the surgeon can ensure the greatest possible therapeutic success and minimize the risk of implant failure. Graphical Abstract

To optimize the thread design of a commercial dental implant for ideal stress distribution in the peri-implant bone. The models of the BLT ® Φ4.1 × 10 implant (Institut Straumann AG) and the alveolar bone were created. Dynamic von Mises stress ( σ vM ) in the peri-implant cortical bone during and immediately after implantation was calculated using explicit dynamics finite element analysis (EDFEA). The combination of thread pitch, depth, tip width (TW), and coronal/apical surface angle (CSA/ASA), which produced minimal σ vM was determined as the optimal thread design by orthogonal experimental design. The implants with optimal and original thread designs were fabricated and implanted into rabbits’ tibias. Implant stability quotient (ISQ), bone-to-implant contact (BIC), and bone volume fraction in 500 μm (BV/TV-500) and 1000 μm range (BV/TV-1000) were measured to evaluate the osseointegration performance of the implants. The implant thread design of 0.8-mm pitch, 0.2-mm depth, 0.15-mm TW, 10-degree CSA, and 10-degree ASA produced minimal σ vM for the maxillary posterior region (OPT-max). The thread design of 1.0-mm pitch, 0.3-mm depth, 0.2-mm TW, 0-degree CSA, and 20-degree ASA produced minimal σ vM for the mandibular posterior region (OPT-man). Optimized implants showed significantly improved ISQ value ( p  < 0.05) 4 weeks after implantation. The BV/TV-500 and BV/TV-1000 around the OPT-max, and the BIC and BV/TV-500 around the OPT-man implant were significantly higher than those around the originally designed implant, respectively ( p  < 0.05). The thread design significantly affects the stress in the peri-implant bone during and immediately after the implantation. The optimal thread design based on EDFEA promoted the osteogenesis around the implant.

Background Dental implants assisting unilateral free end mandibular partial dentures (RPDs) improve their performance and prognosis, however, no consensus exists on the type of thread used in these implants. The current work studied the effect of dental implant thread design on stress distribution around dental implants assisting unilateral free end RPDs using strain gauges and finite element analysis to select the best performing thread design. Methods Twenty-four custom made titanium-aluminum-vanadium (Ti-6Al-4 V) implants were designed and milled 4 thread designs; V-shaped, buttress, reverse-buttress and trapezoid, and were inserted in the approximate locations of tooth number 36 in 6 polymethyl methacrylate Class II Kennedy models, which had teeth number 36, 37, and 38 missing, and unilateral removable partial dentures were constructed to fit each model, with a metal housings and O-rings in their fitting surface attaching to the ball abutment. Surface strains were measured with strain gauges, and mean stresses around the implants, and principal abutments in each tested model were compared using one way analysis of variance (ANOVA). The finite element analysis, recorded stresses, around each dental implant thread design, in the form of colorcoded maps using Von Mises stress analysis. Results The recorded micro-strains around V-shaped threads and their related abutments were higher than those recorded around the buttress threads and their related abutments, reverse buttress threads and their related abutments, and trapezoid threads and their related abutments in descending order as determined by one‑way ANOVA (F = 284.489, p  < 0.001), and Tukey post hoc pairwise comparison ( p  < 0.001). FEA results presented the stresses generated around each thread design, under vertical load, the highest stress concentration values were observed around V-shaped threads, followed by the buttress threads, the reverse buttress threads, and finally the least stresses were observed around the trapezoid threads. Under oblique load, more stresses were observed than those under vertical load, being also greatest around V-shaped threads, then decreasing around buttress, reverse buttress, and trapezoid threads. Conclusions The strain gauge and finite element analysis revealed that the trapezoid threads demonstrated least stress concentration at the bone implant interface, followed by the reverse buttress, buttress, and finally the V-shaped threads.

This paper proposes an algorithm for the conversion of raster data to hexagonal DGGSs in the GPU by redevising the encoding and decoding mechanisms. The researchers first designed a data structure based on rhombic tiles to convert the hexagonal DGGS to a texture format acceptable for GPUs, thus avoiding the irregularity of the hexagonal DGGS. Then, the encoding and decoding methods of the tile data based on space-filling curves were designed, respectively, so as to reduce the amount of data transmission from the CPU to the GPU. Finally, the researchers improved the algorithmic efficiency through thread design. To validate the above design, raster integration experiments were conducted based on the global Aster 30 m digital elevation dataDEM, and the experimental results showed that the raster integration accuracy of this algorithms was around 1 m, while its efficiency could be improved to more than 600 times that of the algorithm for integrating the raster data to the hexagonal DGGS data, executed in the CPU. Therefore, the researchers believe that this study will provide a feasible method for the efficient and stable integration of massive raster data based on a hexagonal grid, which may well support the organization of massive raster data in the field of GIS.

Threads of dental implants with healing chamber configurations have become a target to improve osseointegration. This biomechanical and histometric study aimed to evaluate the influence of implant healing chamber configurations on the torque removal value (RTv), percentage of bone-to-implant contact (BIC%), bone fraction occupancy inside the thread area (BAFO%), and bone and osteocyte density (Ost) in the rabbit tibia after two months of healing. Titanium implants with three different thread configurations were evaluated: Group 1 (G1), with a conventional “v” thread-shaped implant design; Group 2 (G2), with square threads; and Group 3 (G3), the experimental group with longer threads (healing chamber). Ten rabbits (4.5 ± 0.5 kg) received three implants in each tibia (one per group), distributed in a randomized manner. After a period of two months, the tibia blocks (implants and the surrounding tissue) were removed and processed for ground sectioning to evaluate BIC%, BAFO%, and osteocyte density. The ANOVA one-way statistical test was used followed by the Bonferoni’s multiple comparison test to determine individual difference among groups, considering a statistical difference when p < 0.05. Histometric evaluation showed a higher BAFO% values and Ost density for G3 in comparison with the other two groups (G1 and G2), with p < 0.05. However, the RTv and BIC% parameters were not significantly different between groups (p > 0.05). The histological data suggest that the healing chambers in the implant macrogeometry can improve the bone reaction in comparison with the conventional thread design.

Objectives: We wished to compare the primary and secondary stability of dental implants with a progressive design (PL) versus a conventional thread design (SL) across various clinical settings. Methods: A total of 100 implants (50 PL and 50 SL) were placed in 62 patients. The stability of the implants was assessed using a resonance frequency analysis (RFA) at the time of placement (T1) and 20 weeks postoperatively before prosthetic loading (T2). Bone density was measured in Hounsfield units (HU) using cone-beam computed tomography (CBCT). The ISQ values were recorded for each group and anatomical region, including both inter- and intragroup comparisons over time. Results: Both implant designs showed a significant increase in stability during the healing period. At T1, the ISQ values were comparable between groups (SL: 71.3 ± 8.6; PL: 71.1 ± 8.7). At T2, the ISQ values increased significantly in both groups (SL and PL: p < 0.01), with no statistically significant difference in the degree of the gain in stability. The ISQ values were generally lower in the maxilla compared to those in the mandible. In the posterior mandible, the SL implants demonstrated a greater increase in stability compared to that with the PL implants. A strong positive correlation between the HU and ISQ values was observed for both groups (SL: r = 0.95; PL: r = 1.00), without reaching statistical significance. Conclusions: While the progressive thread design aims to enhance the primary stability, it did not outperform the conventional design in this study. Both implant types proved effective in achieving stable and predictable clinical outcomes.

The surgical effectiveness of dental implants is entirely reliant on the biomechanical behaviour of the implant material, the pitch of the implant, and the kind of implant thread design. An enhancement in the implant’s efficacy may be achieved by the selection of the appropriate settings. This research aimed to examine the stress distribution in cortical and cancelous bone by using various kinds of implant thread designs with a pitch value of 0.8mm and a 30% carbon fiber reinforced plastic (30% CFR-PEEK). 30% CFR-PEEK, which stands for carbon fiber reinforced (30%) poly ether ether ketone, has shown its efficacy as a viable alternative to titanium in orthopaedic applications. This research investigated four implants with distinct thread designs, namely V-thread, square thread, buttress and reverse buttress. The mandibular molar area, consisting of both cortical and cancellous bone, is often regarded as isotropic and homogenous. The implant was created using SolidWorks software, and a vertical force of 200 N was exerted. The stress values were determined by the use of the Finite Element Analysis (FEA) technique using ANSYS software. When the bone implant interface was taken into consideration, the von Mises stresses were found to be at their lowest at the cancellous bone for the V thread design, whereas the square thread design showed the highest stresses at the cancellous bone under 200N axial load. When cortical bone was taken into consideration, the square thread design seemed to have the lowest von Mises stresses, whereas the V thread design had the highest stress value. Therefore, the findings that were obtained may be employed therapeutically for the purpose of making a suitable selection of implant thread design in order to achieve a predicted level of success with implant treatment, within the constraints of this research.