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Objective: The aim of this investigation was to evaluate the effect on clinical and radiological outcomes of the one‐abutment, one‐time protocol (test) versus placing the definitive abutment on the day of functional loading after having disconnected and connected three times the healing abutment during the prosthetic phase (control). Materials and methods: Forty patients with 80 implants were randomly allocated to either the test or the control group. Changes in the radiographic marginal bone levels (MBLs), clinical outcomes, prosthetic‐related outcomes, and patient‐reported outcomes measures (PROMs) were assessed and compared 6 and 12 months after functional loading. Results: Thirty‐seven patients with 74 implants were followed at 12 months. A statistically significant bone remodeling was observed in both groups following implant placement. MBLs were significantly greater in the control group at the 6‐ (−0.13 mm vs. −0.61 mm) and 12‐month visits (−0.01 mm vs. −0.53 mm). Bone loss was significantly greater in the control group from surgery to 6 and 12 months and from loading to 6 and 12 months. The abutment height was significantly greater in the test group, however, there were no significant differences in the restorative angle. Similarly, there were no statistically significant differences between groups for the measured clinical variables (probing depth, plaque, and bleeding index) and PROMs. Conclusions: Disconnecting and reconnecting the healing abutment was associated with significantly higher bone loss after 12 months, as compared to the placement of the definitive abutment at implant installation. [ABSTRACT FROM AUTHOR]

This study conducted five centrifuge model tests to investigate the deformation characteristics of the Geosynthetics Reinforced Soil (GRS) abutments under vertical loads, considering the setback distance a b and beam seat width B as two major influencing factors. Test results show that a linear correlation existed between the maximum lateral facing displacements D L and the maximum settlements at the top of the GRS abutments D v. The a b and the B had different effects on the deformation characteristics of the GRS abutments as well as the relationship between the D L and the D v. The total volumetric strains of the GRS abutments were smaller than 0.3% for all the cases investigated in this study, indicating that it was reasonable to use the assumption of zero-volume change for the deformation calculation of the GRS abutments. This study proposed an improved semi-empirical method to describe the relationship between the D L and the D v. Centrifuge test results and data collected from the literature were used to validate the improved method. It was concluded that the improved method had the advantage of considering the effects of the a b and the B separately and therefore significantly improved the prediction accuracy of the deformations of the GRS abutments. • This study conducted five centrifuge model tests to investigate not only the lateral facing displacements and the settlements at the top of the GRS abutment under vertical loading but also the volumetric deformations which correlate both the lateral and the vertical deformations. • Based on the centrifuge test results and data collected from the literature, this study proposed and verified an improved semi-empirical method to describe the linear correlation between the maximum lateral facing displacements and the maximum settlements of the GRS abutments. • The improved method had the advantages of considering the effects of the setback distance and the beam seat width separately and significantly improves the prediction accuracy of the deformations of the GRS abutments induced by vertical loads. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: The new frontiers of computer-based surgery, technology, and material advances, have allowed for customized 3D printed manufacturing to become widespread in guided bone regeneration (GBR) in oral implantology. The shape, structural, mechanical, and biological manufacturing characteristics achieved through 3D printing technologies allow for the customization of implant-prosthetic rehabilitations and GBR procedures according to patient-specific needs, reducing complications and surgery time. Therefore, the present narrative review aims to elucidate the 3D-printing digital radiographic process, materials, indications, 3D printed manufacturing-controlled characteristics, histological findings, complications, patient-reported outcomes, and short- and long-term clinical considerations of customized 3D printed mesh, membranes, bone substitutes, and dental implants applied to GBR in oral implantology. Methods: An electronic search was performed through MEDLINE/PubMed, Scopus, BioMed Central, and Web of Science until 30 June 2024. Results: Three-dimensionally printed titanium meshes and bone substitutes registered successful outcomes in vertical/horizontal bone defect regeneration. Three-dimensionally printed polymeric membranes could link the advantages of conventional resorbable and non-resorbable membranes. Few data on customized 3D printed dental implants and abutments are available, but in vitro and animal studies have shown new promising designs that could improve their mechanical properties and tribocorrosion-associated complications. Conclusions: While 3D printing technology has demonstrated potential in GBR, additional human studies are needed to evaluate the short- and long-term follow-up of peri-implant bone levels and volumes following prosthetic functional loading. [ABSTRACT FROM AUTHOR]

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Jembatan Jalan Bromo terletak pada Desa Mojounggul, Kecamatan Bareng, Kabupaten Jombang dengan bentang yang direncanakan 10 meter. Jembatan ini awalnya menggunakan struktur pelengkung yang dibangun masa Belanda sehingga harus dilakukan perencanaan struktur jembatan. Di sini peneliti memodifikasi desain jembatan menggunakan balok-T (T-Beam Structure). jembatan Jalan Bromo digunakan sebagai objek penelitian untuk memodifikasi desain struktur jembatan bagian atas yang meliputi: balok-T jembatan dan bangunan bawah meliputi: abutmen, pondasi, dan diafragma dengan menghitung aspek pembebanan mengacu pada SNI 1275-2016, aspek penulangan dan dimensi penulangan pada balok-T, selanjutnya kontrol kekuatan terhadap abutmen dan daya dukung pada tiang pancang. Hasil perhitungan pada redesign jembatan didapatkan hasil momen ultimit (MU) pada balok 116 kNm dan gaya geser ultimit (VU) 598 kN dengan tulangan yang digunakan pada balok tulangan lentur 12 D 32 mm, tulangan bagi 2 D 13 mm tulangan geser D 16-150 mm. Stabilitas guling pada abutmen 12,4 arah x, 4,8 arah y. stabilitas geser pada abutmen didapatkan nilai 14 arah x, dan 432 arah y. Daya dukung tiang pancang 31.899 ton lebih besar dari beban aksial 5.272,2 ton.

Purpose: To quantify the cumulative oral implant survival rates and changes in radiographic bone levels based on the configuration of the implant-abutment connection type over time. Materials and Methods: An electronic literature search was conducted in four databases (PubMed/MEDLINE, Cochrane Library, Web of Science, and Embase), and records were refereed by two independent reviewers based on the inclusion criteria. Data from included articles were grouped by implant-abutment connection type into four categories ([1] external hex; [2] bone level, internal, narrow cone < 45 degrees; [3] bone level, internal wide cone ≥ 45 degrees or flat; and [4] tissue level) and duration of follow-up (short-term 1 to 2 years, mid-term 2 to 5 years, and long-term > 5 years). Meta-analyses were performed for cumulative survival rate (CSR) and changes in marginal bone level (ΔMBL) from baseline (loading) to last reported follow-up. Studies were split or merged as appropriate based on the implants and follow-up duration in the study and trial design. The study was compiled under PRISMA 2020 guidelines and registered in the PROSPERO database. Results: A total of 3,082 articles were screened. Fulltext review of 465 articles resulted in a total of 270 articles (representing 16,448 subjects with 45,347 implants) included for quantitative synthesis and analysis. Mean ΔMBL (95% CI) was as follows: short-term external hex = 0.68 mm (0.57, 0.79); short-term bone level, internal, narrow cone < 45 degrees = 0.34 mm (0.25, 0.43); short-term bone level, internal wide cone ≥ 45 degrees = 0.63 mm (0.52, 0.74); short-term tissue level = 0.42 mm (0.27, 0.56); mid-term external hex = 1.03 mm (0.72, 1.34); mid-term bone level, internal, narrow cone < 45 degrees = 0.45 mm (0.34, 0.56); mid-term bone level, internal wide cone ≥ 45 degrees = 0.73 mm (0.58, 0.88); mid-term tissue level = 0.4 mm (0.21, 0.61); long-term external hex = 0.98 mm, 0.70, 1.25); long-term bone level, internal, narrow cone < 45 degrees = 0.44 mm (0.31, 0.57); long-term bone level, internal wide cone ≥ 45 degrees = 0.95 mm (0.68, 1.22); and long-term tissue level = 0.43 mm (0.24, 0.61). CSRs (95% CI) were: short-term external hex = 97% (96%, 98%); short-term bone level, internal, narrow cone < 45 degrees = 99% (99%, 99%); short-term bone level, internal wide cone ≥ 45 degrees = 98% (98%, 99%); short-term tissue level = 99% (98%, 100%); mid-term external hex = 97% (96%, 98%); mid-term bone level, internal, narrow cone < 45 degrees = 98% (98%, 99%); midterm bone level, internal wide cone ≥ 45 degrees = 99% (98%, 99%); mid-term tissue level = 98% (97%, 99%); long-term external hex = 96% (95%, 98%); long-term bone level, internal, narrow cone < 45 degrees = 98% (98%, 99%); long-term bone level, internal wide cone ≥ 45 degrees = 99% (98%, 100%); and long-term tissue level = 99% (98%, 100%). Conclusion: The configuration of the implant-abutment interface has a measurable effect on the ΔMBL over time. These changes can be observed over a period of at least 3 to 5 years. At all measured time intervals, similar ΔMBL was noted for external hex and internal wide cone ≥ 45-degree connections, as were internal, narrow cone < 45-degree and tissue-level connections. [ABSTRACT FROM AUTHOR]

Abstract Background Marginal misfit and surface roughness of customized implant abutments is critical for restorative success. However, little is known about the comparison of misfit and surface roughness of CAD-CAM Zirconium oxide (ZrO), selective laser melting (SLM) Cobalt Chrome (CoCr) and preformed abutments. The aim of the study is to investigate the relation of misfit and micro-roughness of selective laser melting (SLM), preformed and CAD-CAM implant abutments. Methods Thirty internal connection, endosseous dental implants (Ø 4.0 mm x 10 mm, Dentium) were mounted in Polymethyl methacrylate vertically. Ten preformed Titanium alloy (Ti) abutments with 1 mm soft tissue height and Ø 4.5 mm were included as controls. Ten each of Y-TZP and SLM-CoCr, abutment/crowns were fabricated using CAD-CAM milling (CAD-CAM-ZrO) and SLM techniques. Surface micro-roughness (Ra) of the fabricated implant abutment/crown was evaluated with a 3D optical non-contact microscope. All implant restorations were torqued to implants (30 Ncm) using a Tohnichi BTGE digital torque gauge and were analyzed with Bruker micro-CT (Skyscan 1173) to detect micro-gaps at pre-selected points at implant abutment interface. The Ra and misfit data were compared using ANOVA, Tukey-Kramer, Kruskal-Wallis test and Pearson correlation (p 0.05). Misfit was significantly higher in Y-TZP samples compared to SLM-CoCr (p = 0.031) and preformed Ti abutments (p = 0.01). Preformed Ti abutments showed significantly lower misfit compared to SLM-CoCr abutments (p = 0.01). A positive linear correlation was observed between the surface roughness (Ra) and vertical misfit (r = 0.61, p

Background: Marginal misfit and surface roughness of customized implant abutments is critical for restorative success. However, little is known about the comparison of misfit and surface roughness of CAD-CAM Zirconium oxide (ZrO), selective laser melting (SLM) Cobalt Chrome (CoCr) and preformed abutments. The aim of the study is to investigate the relation of misfit and micro-roughness of selective laser melting (SLM), preformed and CAD-CAM implant abutments. Methods: Thirty internal connection, endosseous dental implants (Ø 4.0 mm x 10 mm, Dentium) were mounted in Polymethyl methacrylate vertically. Ten preformed Titanium alloy (Ti) abutments with 1 mm soft tissue height and Ø 4.5 mm were included as controls. Ten each of Y-TZP and SLM-CoCr, abutment/crowns were fabricated using CAD-CAM milling (CAD-CAM-ZrO) and SLM techniques. Surface micro-roughness (Ra) of the fabricated implant abutment/crown was evaluated with a 3D optical non-contact microscope. All implant restorations were torqued to implants (30 Ncm) using a Tohnichi BTGE digital torque gauge and were analyzed with Bruker micro-CT (Skyscan 1173) to detect micro-gaps at pre-selected points at implant abutment interface. The Ra and misfit data were compared using ANOVA, Tukey-Kramer, Kruskal-Wallis test and Pearson correlation (p < 0.05). Results: Mean Ra among SLM CoCr abutments [0.88 (0.09) µm] were lower than CAD-CAM-ZrO and higher than preformed Ti abutments. Horizontal misfit among SLM-CoCr [45.43 (9.41) µm] and preformed Ti [36.87 (13.23) µm] abutments was not statistically different (p > 0.05). Misfit was significantly higher in Y-TZP samples compared to SLM-CoCr (p = 0.031) and preformed Ti abutments (p = 0.01). Preformed Ti abutments showed significantly lower misfit compared to SLM-CoCr abutments (p = 0.01). A positive linear correlation was observed between the surface roughness (Ra) and vertical misfit (r = 0.61, p < 0.05). Conclusion: SLM CoCr abutments showed rough surface compared to preformed Ti abutments, while horizontal misfit was comparable among SLM-CoCr and preformed abutments. Misfit was significantly greater in Y-TZP abutments, compared to SLM and preformed abutments. SLM abutment fabrication technique needs further improvement to provide better fit and surface topography. [ABSTRACT FROM AUTHOR]

Implant therapy is today widely regarded as a reliable treatment option to replace missing teeth, both for function and esthetics. Dental implants may be used to replace single teeth, replace multiple teeth, or provide abutments for complete dentures or partials. This topic focuses on the placement of dental implants. The correct surgical placement of a dental implant is mandatory to obtain the ideal aesthetic result. Only through proper treatment planning can the correct position and number of implants be determined. Before surgical placement of a dental implant, the adequate hard and soft tissue must be available. The clinician must consider the time needed for implant integration and soft-tissue healing, creation of emergence profiles, occlusal forces in relationship to progressive loading, and occlusal forces on the final restoration. [ABSTRACT FROM AUTHOR]

This case series elaborates on tooth-supported overdenture for prosthetic rehabilitation as a treatment modality in partially edentulous patients. Loss of teeth causes continuous ridge resorption and poor denture foundation affecting the success of prosthesis. Retained natural teeth act as abutments for prosthetic rehabilitation of partial edentulous arches. Tooth-supported overdenture is the mainstay of preventive prosthodontics which preserves natural teeth and/or roots. The cases describe the use of tooth-supported complete overdenture and removable partial overdenture with metal denture base to rehabilitate partially edentulous arches. The natural teeth maintain proprioception and provide additional support, stability, retention, and psychological benefit to the patient than the conventional complete denture with completely edentulous ridges.

Background: The purpose of this study was to analyze the effect of vent hole or peripheral groove on retention of differently angled (15 ° and 30 o) abutments in of cement retained implant supported restorations. Methods: A total of sixty standart implant abutments were used. Abutments were divided into two groups at 15 ° and 30 ° angles on CNC. According to the modification, each group were divided into 3 subgroups; (1) no modifications, (2) with peripheral groove and (3) with vent hole. Sixty metal frameworks were prepared using laser sintering to fit all abutments. All laser sintered frameworks were cemented with eugenol-free provisional cement. Then, all specimens were thermocycled. The frameworks were removed from the abutments by using the universal test machine and the peak removal force was recorded. Statistical analysis were performed with two-way ANOVA, post hoc Tukey’s (HSD) test-adjusted independent samples t-tests. Results: According to the results, there were significant differences between 15 ° and 30 ° groups in terms of retention values (p < 0.001). Additional hole and grooves enhanced retention in both groups. The highest mean value of vertical pull-out strength (185.00 ± 23.08 N) was showed in 15 ° additional grooves group, and the lowest mean value of vertical pull-out strength (27.60 ± 14.84 N) was showed in 30° control group. Means values of additional groove specimens had the highest scores in both groups. In all groups, there were significant differences between all subgroups (p < 0.05). Conclusion: Increased abutment angle decreases retention, while addition of hole and groove increases.

Support and stability for a Removable Partial Denture (RPD) are difficult to achieve in a distal extension edentulous ridge and are even more compromised in reduced dentition. The combination of the altered cast technique and milled crown in removable partial denture fabrication would greatly enhance support by redistributing the load more effectively. However, it is not routinely practiced due to the complexity of the treatment and the lack of emphasis in dental curriculum. In the present case of a 54-year-old male, despite several attempts at wearing the denture, the patient was unable to tolerate it. The atrophic mandibular ridge and poor inclination of the abutment tooth seemed to be complicating factors. Therefore, the prosthesis required some modifications. The present case report highlights the Applegate altered cast technique, which can be deployed with a milled crown, including the clinical and laboratory stages involved. This might help to overcome the problems encountered with distal end saddle dentures, making them more tolerable to patients.

Purpose: To evaluate the fracture load of monolithic, single-tooth implant-supported crowns cemented on solid or Ti-base (Variobase C) abutments. Materials and Methods: Besides abutment types (solid and Ti-base abutments), two ceramic systems (IPS e.max CAD and Zirconia inCoris ZI) and two occlusal thicknesses (0.5 and 1.5 mm) were also investigated in this study. In total, eight groups (n = 8) with 64 maxillary second premolar crowns were fabricated. All the crowns were cemented with resin cement, and the screw accesses in Ti-base groups were sealed with composite resin. After mechanical cycling, the specimens were submitted to fracture load test with the maximum force recorded in Newtons (N). Three-way analysis of variance (ANOVA) and Tukey post hoc test were used for statistical analyses (α = .05). Results: Both the abutment type (P = .0001) and the ceramic system (P = .0001) significantly affected the results. Screw-access channels reduced the fracture load of crowns by half compared to those cemented on solid abutments. The 1.5-mm and 0.5-mm zirconia crowns placed on solid abutments had similar highest fracture loads, while the e.max CAD groups positioned on Ti-base abutments showed significantly lower values compared with other groups. Conclusion: The screw access reduces the resistance of crowns supported by Ti-base abutments compared to crowns cemented on solid abutments. The inCoris ZI showed a higher fracture load than the IPS e.max CAD regardless of the abutment type and thickness. [ABSTRACT FROM AUTHOR]

Purpose: The "one-abutment, one-time" concept entails the placement of a definitive abutment at the time of implant placement, without removal during prosthesis manufacture, with the aim to promote a safer environment for the periimplant tissues. Identifying surgical and radiographic parameters that can assist with the abutment height selection would facilitate the adoption of the one-abutment, one-time concept. Therefore, the aim of this study was to assess the role of surgical and radiographic parameters as predictive factors for abutment height selection in implant-retained single crowns. Materials and Methods: This prospective study assessed the role of surgical and radiographic measurements in the implant survival and success rates and marginal bone loss in implant-retained single crowns. Implants were placed in both healed sites and extraction sockets, and the distances between the implant platform and alveolar bone crest, implant platform and gingival margin, and buccal gap (when present) were recorded using a straight periodontal probe. Digital radiographs were made at implant placement (T0), abutment height selection (Ta), and 1-year follow-up (Tf), and the distance between the implant platform and the alveolar bone crest (mm) was assessed. Linear regression models and Pearson correlation were used to assess the influence of primary and secondary outcomes on abutment height. Results: A total of 130 implants were placed in 68 patients. The mean surgical distance between the bone crest and the implant platform was 1.71 ± 1.01 mm, and the mean distance from the gingival margin to the implant platform was 3.94 ± 1.90 mm, while at the abutment selection appointment, the mean transmucosal height was 3.58 ± 1.50 mm. A high linear correlation was found between the selected abutment height and two primary outcomes: the radiographic implant platform to alveolar bone crest distance at T0 (r² = 0.66; P < .001) and the transmucosal height at Ta (r² = 0.81; P < .001). Conclusion: Radiographic measurements of the distance between the implant platform and the alveolar bone crest at implant placement can serve as an important parameter to select the abutment height for definitive restorations. [ABSTRACT FROM AUTHOR]

Copyright of Structural Integrity & Life / Integritet i vek Konstrukcija is the property of University of Belgrade, Faculty of Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The use of titanium as a biomaterial for the treatment of dental implants has been successful and has become the most viable and common option. However, in the last three decades, new alternatives have emerged, such as polymers that could replace metallic materials. The aim of this research work is to demonstrate the structural effects caused by the fatigue phenomenon and the comparison with polymeric materials that may be biomechanically viable by reducing the stress shielding effect at the bone–implant interface. A numerical simulation was performed using the finite element method. Variables such as Young's modulus, Poisson's coefficient, density, yield strength, ultimate strength, and the S-N curve were included. Prior to the simulation, a representative digital model of both a dental implant and the bone was developed. A maximum load of 550 N was applied, and the analysis was considered linear, homogeneous, and isotropic. The results obtained allowed us to observe the mechanical behavior of the dental implant by means of displacements and von Mises forces. They also show the critical areas where the implant tends to fail due to fatigue. Finally, this type of non-destructive analysis proves to be versatile, avoids experimentation on people and/or animals, and reduces costs, and the iteration is unlimited in evaluating various structural parameters (geometry, materials, properties, etc.). [ABSTRACT FROM AUTHOR]

The findings of numerous analytical/computational studies, tests, and in-situ observations have highlighted the importance of the deck-abutment-backfill interaction on the seismic response of bridges. These findings have allowed various researchers to develop models for the nonlinear behaviour of the abutment-backfill system. Such models have been extensively used in research, and the simpler among them have been adopted by modern seismic codes and guidelines and have also been incorporated in programs for the nonlinear analysis of structures. Although large-scale tests have captured the behaviour of the abutment-backfill system subsequent to the attainment of peak strength, this critical phase of the response has neither been studied to a sufficient extent from the analysis point of view, nor included in the constitutive models of available nonlinear analysis programs. The softening region of the response of the backfill has been addressed using a number of hardening/softening plasticity models that are rarely used in practical analysis wherein simpler models (like Winkler springs) are typically preferred. Capturing the post-peak range of the abutment-backfill response is very significant in seismic fragility analysis of bridges for the definition of limit states close to failure. In the above context, the main aim of the work presented herein is to introduce a new model capturing this range of the backfill response; it is an extended version of the 'Hyperbolic Gap' 'material' in OpenSees, named 'Hyperbolic Gap Softening' material, which allows the user to define a set of parameters that describe the softening branch of the backbone curve of an abutment-backfill system. In addition to tests of the new model using a simple structural configuration, results of response history analyses of a case-study bridge with different abutment-backfill properties are also reported, with a view to verifying the applicability of the proposed model and assessing the importance of capturing the post-peak abutment-backfill behaviour on the assessment of the seismic response of a bridge. [ABSTRACT FROM AUTHOR]

Support and stability for a Removable Partial Denture (RPD) are difficult to achieve in a distal extension edentulous ridge and are even more compromised in reduced dentition. The combination of the altered cast technique and milled crown in removable partial denture fabrication would greatly enhance support by redistributing the load more effectively. However, it is not routinely practiced due to the complexity of the treatment and the lack of emphasis in dental curriculum. In the present case of a 54-year-old male, despite several attempts at wearing the denture, the patient was unable to tolerate it. The atrophic mandibular ridge and poor inclination of the abutment tooth seemed to be complicating factors. Therefore, the prosthesis required some modifications. The present case report highlights the Applegate altered cast technique, which can be deployed with a milled crown, including the clinical and laboratory stages involved. This might help to overcome the problems encountered with distal end saddle dentures, making them more tolerable to patients. [ABSTRACT FROM AUTHOR]

La socavación de las cimentaciones puede causar fallas estructurales con graves consecuencias. El proceso de socavación tiene un carácter progresivo y, dependiendo de las condiciones en las que se desarrolla, los efectos de este proceso podrían ser controlados oportunamente para evitar el colapso de las estructuras. Este artículo presenta los resultados de la modelización numérica mediante elementos finitos del colapso del puente de la calle Arturo Sandez en el cantón Girón, Ecuador. El análisis se realizó en un modelo de elementos finitos sólidos en el programa Midas Civil. El estudio del estado tenso-deformacional del puente se realizó en diferentes etapas de socavación y los resultados obtenidos demuestran que, si durante una valoración física se detectan daños en una estructura, entonces es necesario realizar una evaluación numérica de su estado tenso-deformacional. Esta acción permitirá pronosticar la evolución del estado tenso-deformacional de la estructura y tomar las medidas correctivas de manera técnica y oportuna para prevenir el colapso. Este estudio muestra que la socavación inicialmente detectada casi un año antes del colapso constituía un 5.86% de la superficie de cimentación, el inicio del fallo del estribo izquierdo se produjo cuando el área de la socavación alcanzó el 25.48%, y el fallo irreversible de la estructura se produjo cuando la socavación alcanzó un el 39.41% de la superficie de cimentación. Los resultados expuestos demuestran que una modelización numérica pudo prevenir el colapso del puente y permitir tomar las medidas necesarias de mitigación. Abstract Foundation scour can cause structural failure with serious consequences. The scour process has a progressive character and, depending on the conditions under which it develops, the effects of this process can be controlled in a timely manner to avoid the collapse of structures. This paper presents the results of the numerical modelling of the collapse of the Arturo Sandez bridge in Girón, Ecuador. The analysis was performed in a solid finite element model in the Midas Civil software. The study of the stress-strain state of the bridge was carried out at different stages of scour and the results obtained show that, if damage to a structure is detected during a physical assessment, it is necessary to carry out a numerical evaluation of its stress-strain state. This action will allow the stress-strain state of the structure to be predicted and corrective measures to be taken in a technical and timely manner to prevent collapse. This study shows that the scour initially detected almost one year before the collapse constituted 5.86% of the foundation area, the onset of failure of the left abutment occurred when the scour area reached 25.48%, and the irreversible failure of the structure occurred when the scour reached an area of 39.41%. The above results demonstrate that numerical modelling was able to prevent the collapse of the bridge and allow the necessary mitigation measures to be implemented.

Today, abutments disrupt the normal flow of rivers and cause scouring and erosion of sedimentary materials around them, creating holes and resulting in much damage every year. Researchers have proposed various methods to reduce the power of water erosion. One of the essential methods in this regard is creating slots in abutments. Since the expansion of the scour hole endangers the stability of the bridge structure, this study examined the effect of slot dimensions in the support on the scour hole dimensions. The findings demonstrated that the presence of slots in abutments effectively reduces the dimensions of scour holes. With the slot, the volume of the scour hole can be reduced by up to 50%. Furthermore, as the relative speed of scouring increases by 75%, the depth of the scour hole also increased up to 140%. An increase in slot depth leads to a decrease in scour hole depth of up to 85%.

Abstract Background In-vitro data from a clinically well-known lithium disilicate ceramic reference was used to assess the expected performance of resin-based materials in implant dentistry. The purpose of the study was to compare the bond strength and marginal adaptation of nano-ceramic hybrid composite crowns cemented to stock cement-retained abutments to lithium disilicate crowns. Methods Twenty abutment analogs were embedded into auto-polymerizing acrylic resin blocks. The blocks were divided into 2 groups according to the restorative crown material. The 2 groups were divided as follows: Resin nano-ceramic group and lithium disilicate group. Abutment analogs in both groups were scanned using a laboratory scanner, and the restorations were designed, manufactured, and cemented with resin cement over the corresponding group. All samples were tested for marginal adaptation and bond strength after storage for 24 hours at 37 °C in 100% humidity. Data were collected, tabulated, and statistically analysed using the appropriate tests. Normality was checked using Shapiro Wilk test and Q-Q plots. Data were normally distributed. Variables were presented using mean, 95% Confidence Interval (CI) and standard deviation in addition to median and Inter Quartile Range (IQR). Differences between groups regarding debonding forces was assessed using independent t test. Two Way ANOVA was performed to assess the effect of material and bonding on marginal gap. All tests were two tailed and p value was set at

Today, abutments disrupt the normal flow of rivers and cause scouring and erosion of sedimentary materials around them, creating holes and resulting in much damage every year. Researchers have proposed various methods to reduce the power of water erosion. One of the essential methods in this regard is creating slots in abutments. Since the expansion of the scour hole endangers the stability of the bridge structure, this study examined the effect of slot dimensions in the support on the scour hole dimensions. The findings demonstrated that the presence of slots in abutments effectively reduces the dimensions of scour holes. With the slot, the volume of the scour hole can be reduced by up to 50%. Furthermore, as the relative speed of scouring increases by 75%, the depth of the scour hole also increased up to 140%. An increase in slot depth leads to a decrease in scour hole depth of up to 85%. [ABSTRACT FROM AUTHOR]

Dental implants have been a popular treatment for replacing missing teeth. The purpose of this study was to investigate the impact of engaging (hexagonal) and non-engaging (non-hexagonal) abutments in various six-unit fixed prosthesis on the stress distribution and loading located in the implant neck, implant abutment, and surrounding bone. Three implants were digitally designed and inserted parallel to each other in edentulous sites of the maxillary right canine, maxillary right central incisor, and maxillary left canine. Titanium base engaging abutments, non-engaging abutments and connecting screws were designed. Five distinct models of 6-unit fixed dental prosthesis were created, each featuring different combinations of various abutments. Forces (45-degree angle) were applied to the prosthesis, allowing for the analysis of the stress distribution on the implant neck and abutments, and the maximum and minimum principal stress values on the cortical and trabecular bone. Von Mises stress values and stress distributions located in the implant neck region due to the applied loading forces were analyzed. The overall stress values were highest while employing the hexagonal abutments. The maxillary left canine with a hexagonal abutment (model 5) reported the highest von mises value (64.71 MPa) while the maxillary right canine with a non-hexagonal abutment (model 4) presented lowest von mises value (56.69 MPa). The results suggest that both the various abutment combinations (engaging and non-engaging) on five different models have a similar influence on the distribution of stress within the implant system. [ABSTRACT FROM AUTHOR]

Copyright of Selcuk Dental Journal is the property of Selcuk Dental Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: In-vitro data from a clinically well-known lithium disilicate ceramic reference was used to assess the expected performance of resin-based materials in implant dentistry. The purpose of the study was to compare the bond strength and marginal adaptation of nano-ceramic hybrid composite crowns cemented to stock cement-retained abutments to lithium disilicate crowns. Methods: Twenty abutment analogs were embedded into auto-polymerizing acrylic resin blocks. The blocks were divided into 2 groups according to the restorative crown material. The 2 groups were divided as follows: Resin nano-ceramic group and lithium disilicate group. Abutment analogs in both groups were scanned using a laboratory scanner, and the restorations were designed, manufactured, and cemented with resin cement over the corresponding group. All samples were tested for marginal adaptation and bond strength after storage for 24 hours at 37 °C in 100% humidity. Data were collected, tabulated, and statistically analysed using the appropriate tests. Normality was checked using Shapiro Wilk test and Q-Q plots. Data were normally distributed. Variables were presented using mean, 95% Confidence Interval (CI) and standard deviation in addition to median and Inter Quartile Range (IQR). Differences between groups regarding debonding forces was assessed using independent t test. Two Way ANOVA was performed to assess the effect of material and bonding on marginal gap. All tests were two tailed and p value was set at < 0.05. Results: Marginal gap and debonding force values were significantly different according to the type of material used (P <.05). Resin nano-ceramic crowns presented lower marginal gap values before (20.80 ± 8.87 μm) and after (52.11 ± 22.92 μm) bonding than lithium disilicate crowns. The debonding force value for resin nano-ceramic crowns (284.30 ± 26.44 N) was significantly higher than that for lithium disilicate crowns (253.30 ± 33.26 N). Adhesive failure mode was detected in all the specimens in both groups. Conclusions: The type of material used for implant-supported cement-retained crowns had a statistically significant effect on marginal adaptation and bond strength. Resin nano-ceramic implant-supported cement-retained crowns had better marginal adaptation and higher bond strength than those manufactured using lithium disilicate. [ABSTRACT FROM AUTHOR]

Statement of problem: The extraction of fractured abutment screws can be a difficult challenge to overcome. Purpose: To compare the removal capacity, dental implant connection damage, and time required to remove the fractured abutment screws between three drilling techniques and a conventional method. Materials and methods: A total of 180 prefabricated screw-retained abutments were intentionally fractured in internal connection dental implants after being subjected to a cyclic load and a static compression load. Afterwards, three operators randomly removed the fractured abutment screws with the following drilling techniques and a conventional method: A: a conventional technique using an exploration probe and ultrasonic appliance (n = 45), Rhein83® (n = 45); B: Sanhigia® (n = 45); C: Phibo® (n = 45). Two-way ANOVA models were estimated to evaluate the mean time according to the method and operator used. Results: The probability of removal of the screws with mobility was twelve times higher than that of the screws without mobility (OR = 12.4; p < 0.001). The success rate according to the operators did not show statistically significant differences (p = 0.371). The location of the fractured screw did not affect removal success (p = 0.530). The internal thread of the implant was affected after the removal process in 9.8% of the cases. The mean extraction time was 3.17 ± 2.52 min. The Rhein83® method showed a success rate of 84.4%, followed by the Phibo® and conventional methods (71.1%) and the Sanhigia® method (46.7%). Conclusions: The Rhein83® drilling technique increases the removal probability of fractured abutment screws. The initial mobility of the fragment is also a significant factor in the removal success. [ABSTRACT FROM AUTHOR]

The article describes the product range of the company Zirkonzahn, which offers components for more than 140 implant systems. The company produces all products itself and uses a medical titanium alloy. New components are introduced, including the Zirkonzahn LOC-Connectors anchoring system for implants and bridges for the fixation of removable dental prostheses. In addition, angled Zirkonzahn Multi Unit Abutments and titanium bases for stability and aesthetics are mentioned. The titanium bases can be gold-plated or anodized to improve biocompatibility and promote osseointegration. Zirkonzahn also offers a warranty of up to 30 years on their implant structures. [Extracted from the article]

Abstract Background It is well established that nanotopography and wettability of implant surfaces contribute to osseointegration and long-term implant success. However, the effects of a hydrogenated surface with nanotubular and superhydrophilic properties on peri-implant soft tissue remain unclear. This study was designed to study the impact of a modified abutment surface on early soft tissue integration compared with a machined surface. Methods Thirty-six implants were placed at the bone level in the bilateral mandible of six beagles, followed by healing abutments belonging to the standard machined Ti-6Al-4V alloy abutments (TC4-M), anodized abutments with nanotubes (TC4-Nano), and hydrogenated abutments (TC4-H/Nano) groups, which were randomly screwed to the implants. After two and four weeks of wound healing, the animals were euthanized for histological evaluation. Results A superhydrophilic nanotubular surface developed on the hydrogenated abutment. Histological and histometric analyses revealed similar peri-implant soft tissue healing and dimensions for the three types of abutments at two and four weeks. Connective tissue (CT) length was longer around TC4-H/Nano abutments compared with standard abutments; however, the differences were not statistically significant. Moreover, collagen fibers in the TC4-H/Nano group extended and were attached perpendicularly to the superhydrophilic surface. Conclusions Our results revealed that the soft tissue interface adjacent to the hydrogenated abutment is comparable to that of the machined abutment. A tendency of increased CT length and perpendicular collagen fibers was observed around the modified abutment. This study suggests that nanotubular/superhydrophilic surfaces could be a promising modification to enhance soft tissue sealing. However, comprehensive studies should be conducted to evaluate the peri-implant soft tissue around the modified abutment immunohistochemically, histopathologically, and clinically.

Purpose: The aim of this systematic review was to evaluate the influence of zirconia and titanium as abutment materials on peri-implant soft tissue color. Materials and Methods: The searched electronic databases included MEDLINE/PubMed, LILACS, Web of Science, Scopus, and LIVIVO. Two types of studies were included: randomized clinical trials (RCTs) and controlled clinical trials (CCTs) that compared zirconia (Zr) and titanium (Ti) abutments. The outcomes measured were as follows: implant crown esthetic index, visual analog scale, esthetic index, gingiva discoloration index-spectrophotometry, papilla index, recession index, and pink esthetic score. Two reviewers selected the records, assessed quality, and extracted data of included studies independently. Results: A total of 323 patients enrolled in 13 studies were included in this analysis with 11 RCTs and 2 CCTs. Due to the wide variety of methodologies used, meta-analysis was only possible for RCTs that performed spectrophotometric analysis. The use of zirconia or titanium for implant abutments does not seem to be the principal factor for influencing peri-implant soft tissue color. The meta-analysis showed no difference between zirconia and titanium abutments. Conclusion: This study does not support any better advantage of the use of zirconia in comparison to the use of titanium related to peri-implant tissue color. [ABSTRACT FROM AUTHOR]

Abstract Objective To evaluate and compare the impact of two removable partial dentures (acrylic removable partial denture [ARPD] and metallic removable partial denture [MRPD]) on periodontal tissues of the remaining teeth in the first 12 months of denture use. Materials and Methods This prospective clinical study included 40 patients, of which 20 received ARPDs, 20 received MRPDs, nine in the maxilla, and 11 in the mandible each. The patients were 45–65 years old; 24 were females, and 16 were males. Patients’ demographic details, clinical indicators of periodontal complications, and biochemical measurement of Hs‐C‐reactive protein (CRP) and alkaline phosphatase (ALP) were considered. One‐way analysis of covariance and Friedman were used to measure the differences in clinical periodontal parameters between the two types of dentures. Results The significant findings were: Plaque index (PLAQ) scores for abutment teeth were higher in MRPD wearers (mean = 12.15) than ARPD wearers (mean = 10.45), whereas ARPD users had significantly higher mean bleeding on probing (BOP) values (mean = 1.5) than MRPD users (mean = 0.00); mobility of abutment teeth showed no significant differences; timeline comparisons showed a significant increase in the percentage of nonabutment teeth mobility in ARPD users (p = .028) compared with MRPD users over the same follow‐up period (p = .102). Conclusions For a short‐term period of 1 year, periodontal and mobility parameters have no significant impact on the abutment and nonabutment teeth of ARPD and MRPD users. Moreover, biochemical markers (CRP and ALP) for periodontal inflammation exhibited no significant difference in both types of dentures.

One of the causes of the failure of dental implants is bone loss due to bacterial infiltration. To minimize this problem, biofilm adhesion on the abutments must be avoided to improve soft tissue sealing. The present work aimed the functionalization of titanium abutment surface with antimicrobials graphene oxide and copper oxide. The samples were divided into 4 groups: G1 (Cu2O coating); G2 (GO coating); G3 (GO + Cu2O coating) and G4 (no coating). They were characterized by Scanning Electron Microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, roughness, and wettability. Bacterial viability on the abutment surface was also investigated using a qualitative live/dead assay. After surface functionalization, all groups had adequate roughness values for soft tissue sealing, less than 0,4 μm. G1 samples had the lowest wettability (2.16 ± 6.23 mJ/m2). The surface of G2 samples had the largest number of dead bacteria (226.334 AU/42.38%). The roughness of G3 (0.094 ± 0.018 μm) had the most similarity to that of natural teeth (0.099 μm). G4 samples had the highest wettability (38.57 ± 10.51 mJ/m2) and allowed the greatest adherence of S. mutans strains (399.056 AU/32.10%).

Abstract Background The purpose of this study is to investigate the performance and fracture resistance of different resin-matrix ceramic materials for use in implant-supported single crowns with respect to the abutment design (crown thickness: 1 mm, 2 and 3 mm). Methods Forty-eight abutments and crowns were fabricated on implants in the right lower first molar. Two resin-matrix ceramic materials for dental crowns were selected for study: (1) a glass-ceramic in a resin interpenetrating matrix (Vita Enamic, Vita, Germany) and (2) a resin-based composite with nanoparticle ceramic filler (Lava Ultimate, 3 M ESPE, USA). Three types of abutments were designed: 1 mm thick crown + custom titanium abutment, 2 mm thick crown + custom titanium abutment and 3 mm thick crown + prefabricated titanium abutment. The experiment was divided into 6 groups (n = 8) according to the crown materials and abutment designs. After 10,000 thermocycles, fracture resistance was measured using a universal testing machine. The statistical significance of differences between various groups were analysed with ANOVA followed by a post hoc Tukey’s honestly significant difference test. The surfaces of the fractured specimens were examined with scanning electron microscopy (SEM). Results Two-way ANOVA revealed that the abutment design (F = 28.44, P = 1.52 × 10− 8

Scouring around bridge abutments is a crucial and complex process that sometimes may lead to the failure of the bridge abutment. Therefore, in the present research, scouring around bridge abutments under clear water conditions was examined without and with countermeasures for providing an economical solution. A total of forty-five experiments were performed under clear water conditions to find the maximum scour depth around the bridge abutment. Experiments were performed in two different phases. In the first phase, scour depth was investigated without any countermeasures. In the second phase, scour depth was investigated using marble and brick waste as a countermeasure. The results showed that the maximum scour depth around the bridge abutment (at a distance of 10 cm on the upstream side and 15 cm on the downstream side of the abutment) for the Froude's number of 0.22 was 0.137 m without any countermeasure. The scouring depth increased up to 40% with an increase in the Froude's number from 0.13 to 0.22. The maximum reduction of scour depth was observed to be 40% and 55% when brick and marble waste were used as a countermeasure, respectively, compared to without a countermeasure case. It was concluded that marble and brick waste not only reduced scour depth to a significant level but also provided an economical solution. [ABSTRACT FROM AUTHOR]

Metals subjected to the oral environment are prone to corrosion over time and this can be harmful. Metallic restoration components such as dental subgingival implant abutments are exposed to pH changes and different ions while in contact with saliva. The aim of the study was to evaluate the corrosion resistance of titanium dental implant abutments and to compare and contrast the surface characteristics of these alloys before and after corrosion. The corrosion examination (Ecorr, jcorr, OCP, polarization curve) of two implant abutments (TiDesign EV, Astra Tech, Dentsply, York, PA, USA; Individual Titanium Abutment, Apollo Implants Components, Pabianice, Poland) was performed in 0.9% NaCl and 5% HCl. Moreover, specimens were investigated using SEM-EDS before and after the corrosion test. The value of jcorr in NaCl was higher for Astra (34.2 × 10−8 ± 2.5 × 10−8 A/cm2) than for Apollo (8.8 × 10−8 ± 2.5 × 10−8 A/cm2). Whereas, in HCl, the opposite relationship was observed (Astra 2.9 × 10−4 ± 0.8 × 10−4 A/cm2 and Apollo 62.7 × 10−4 ± 9.3 × 10−4 A/cm2). An average reactive anodic current density in NaCl for Astra amounted up to ~0.2 × 10−5–1.5 × 10−5 A/cm2, while for Apollo-up to ~3.3–9.7 × 10−7 A/cm2. The composition of both alloys after corrosion in NaCl demonstrated some changes: a decrease in the Ti, and Al and an increase in oxygen content. Hence, both alloys after corrosion in HCl demonstrated some minor changes in the elemental composition. Based on the results it can be concluded that: 1. Astra and Apollo abutments revealed good corrosion resistance and a passivation layer on the surface. 2. Apollo abutments exhibited better corrosion resistance in a neutral environment, suggesting that Astra abutments were found to be more resistant to corrosion in an acidic medium. [ABSTRACT FROM AUTHOR]

Excessive surface settlement of fill behind abutment and high lateral earth pressure acting on the abutment wall will develop abutment movement and bump at the end of the bridge. A crucial approach to solving these problems is to select a proper backfill and disposal scheme behind the abutment. The present study is aimed to examine the pressure and deformation properties of various fills behind the bridge abutment by the use of centrifuge. The experimental design follows the similitude relationship of centrifugal model test. This includes scaling of model geometry, geosynthetic reinforcement stiffness, backfill soil modulus, EPS interlayer modulus, and abutment back structure and foundation. Finally, the test results of centrifugal model are compared with the field measurement results. The achieved results indicate that the earth pressure and surface settlement of ceramsite fly ash concrete behind abutment are remarkably lower than those of other backfill, which could be preferred as backfill materials. Further, the higher compaction level of the backfill leads to a decrease in the settlement of the backfill. It is also noticed that the geogrid reinforcements result in the enhancements of the strength of the backfill and the reduction of the lateral earth pressure exerting on the back of the abutment. Additionally, the earth pressure of backfill is noticeably lessened after installing the EPS panel on the back of the abutment, and for the structure equipped with geogrid reinforcement and EPS panel, further lessening of the earth pressure is detectable. Finally, the normalized soil settlement of the pile-supported abutment is remarkably higher than that of the gravity abutment, and the deformation characteristics of backfill considerably are determined by supporting capacity of the subgrade. The present research provides a preliminary basis for decreasing the bump at the end of the bridge. [ABSTRACT FROM AUTHOR]

Purpose: This systematic review aimed to evaluate the effect of the abutment material on peri-implant soft tissue health and stability. Study Selection: An electronic and hand search was conducted until February 2022. Only prospective randomized trials (RCTs) and controlled clinical trials (CCTs) comparing titanium abutments with abutments made of different materials, with a follow-up of at least 6 months, were selected by two independent reviewers. Data on marginal bone loss (MBL) and periimplant tissue indexes, i.e., plaque index (PI), bleeding on probing (BOP), probing depth (PD), and recession (REC), were collected. The risk of bias for RCTs and non-RCTs was evaluated according to the tool reported in the Cochrane Handbook for Systematic Reviews of Interventions and the ROBINS-I tool, respectively. Both pairwise and network meta-analyses (NMA) were performed. Results: We included 18 relevant studies from 1,437 identified studies. Overall, 612 patients were treated, and 848 abutments were inserted. Five studies presented a low risk of bias. Pairwise meta-analysis showed that, as compared to titanium, zirconia abutments presented a significantly reduced MBL (0.20 mm, 95% Confidence Interval CI [0.14-0.26], P < 0.00001). No significant differences were found for the other outcomes. In the NMA, zirconia abutments demonstrated an 83.3% probability of achieving the highest rank in PI, an 87.0% in BOP, and a 65.0% in PD outcome, suggesting that zirconia abutments generally performed better than titanium and alumina abutments. Conclusions: Within the limits of the present study, zirconia abutments seem a viable alternative to titanium ones. [ABSTRACT FROM AUTHOR]

The present study focused on investigating whether universal screwdriver kits cause less friction between the screwdriver and the abutment screw than original screwdrivers. For this purpose, 2 original screwdrivers (Straumann and BEGO) and a universal screwdriver kit (bredent) were investigated. On 1 implant per screwdriver, 26 abutments were properly attached one after the other with the corresponding abutment screws. After tightening the abutment screw, the force required to pull the screwdriver off the screw head was determined with a spring balance. For both manufacturers, greater pull-off forces were measured when using the original screwdrivers than when using the universal screwdriver. The pull-off force (mean ± SD) required for the Straumann original screwdriver was 3.7 ± 1.4 N, while that required for the universal screwdriver was 0.1 ± 0.1 N (P <.001). The pull-off force was 1.5 ± 1.5 N for the BEGO original screwdriver and 0.7 ± 0.9 N for the universal screwdriver (P =.19). Using original manufacturer-supplied screwdrivers could thus minimize the risk of the screwdriver slipping out of the screw head during dental treatment and being swallowed or aspirated by the patient. [ABSTRACT FROM AUTHOR]

Background: It is well established that nanotopography and wettability of implant surfaces contribute to osseointegration and long-term implant success. However, the effects of a hydrogenated surface with nanotubular and superhydrophilic properties on peri-implant soft tissue remain unclear. This study was designed to study the impact of a modified abutment surface on early soft tissue integration compared with a machined surface. Methods: Thirty-six implants were placed at the bone level in the bilateral mandible of six beagles, followed by healing abutments belonging to the standard machined Ti-6Al-4V alloy abutments (TC4-M), anodized abutments with nanotubes (TC4-Nano), and hydrogenated abutments (TC4-H/Nano) groups, which were randomly screwed to the implants. After two and four weeks of wound healing, the animals were euthanized for histological evaluation. Results: A superhydrophilic nanotubular surface developed on the hydrogenated abutment. Histological and histometric analyses revealed similar peri-implant soft tissue healing and dimensions for the three types of abutments at two and four weeks. Connective tissue (CT) length was longer around TC4-H/Nano abutments compared with standard abutments; however, the differences were not statistically significant. Moreover, collagen fibers in the TC4-H/Nano group extended and were attached perpendicularly to the superhydrophilic surface. Conclusions: Our results revealed that the soft tissue interface adjacent to the hydrogenated abutment is comparable to that of the machined abutment. A tendency of increased CT length and perpendicular collagen fibers was observed around the modified abutment. This study suggests that nanotubular/superhydrophilic surfaces could be a promising modification to enhance soft tissue sealing. However, comprehensive studies should be conducted to evaluate the peri-implant soft tissue around the modified abutment immunohistochemically, histopathologically, and clinically. [ABSTRACT FROM AUTHOR]

Copyright of ABE: Advances in Building Education is the property of Departamento de Tecnologia de la Edificacion, Universidad Politecnica de Madrid and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: The objective of this study was to evaluate the influence of the oxide layer removal procedure using acid on the roughness and internal fit of overcast universal castable long abutments (UCLAs) for a taper connection. Materials and Methods: For this, maxillary first premolars were waxed on the plastic sleeve of 15 UCLAs with a premachined interface. The specimens were overcast using the NiCr alloy, and the frameworks were randomly distributed to undergo one of two different oxide layer removal methods: blasting with 100-µm particles of aluminum oxide at 0.60-MPa pressure or bathing for 5 hours in 0.5% hydrofluoric acid. The surface roughness was evaluated by a light interferometer at the subcritical contour of each abutment. Next, the frameworks were attached to the respective analogs for internal fit evaluation. The central cross section of each assembly was exposed, and three regions were visualized by scanning electron microscopy (SEM): taper interface, axial wall, and index region. The premachined base was used as the control. The groups were compared using analysis of variance (ANOVA) and Tukey post hoc test (a = .05). Results: The results showed that acid bathing produced intermediary roughness between premachined and blasted surfaces (P < .05). SEM images showed a sealed interface at the taper region of all groups, despite some irregularities after alumina blasting. Increased discrepancies at the axial wall and index region were found after the alumina blasting procedure (P < .05). Conclusion: It was concluded that acid bathing should be used, instead of blasting to remove the oxide layer, to produce a better fit and smoother surface on UCLAs. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this in vitro study was to evaluate the load-to-fracture values of cement-, screw-, and multiscrew-retained abutments for implant-supported fixed partial dentures (FPDs). Materials and Methods: Thirty-six implants with a diameter and length of 4.5 and 13 mm, respectively, were used to prepare 18 samples of FPDs. Based upon the variations on abutment design, the FPDs were divided into three categories as follows: cement-retained, screw-retained, and multiunit screw-retained abutments. Using a chewing simulator, cyclic loads of 1,250,000 load cycles with a load of 70 N were applied on all samples to simulate 5 years of human functional chewing. The samples were loaded until failure using an electromechanical test machine. Sample-size estimation was done, and fracture-load values were recorded as means and corresponding standard deviations; group comparisons were done using one-way analysis of variance and Tukey post hoc tests. A P value < .01 was considered as an indicator of statistical significance. Results: The fracture-load values for cement-, screw-, and multiunit screw-retained abutments were 2,109.2 ± 139.6 N, 3,888.8 ± 70 N, and 3,319.4 ± 218.9 N, respectively. The load-to-fracture values were significantly higher in screw-retained abutments (3,888.8 ± 70 N; P < .001) than in cement-retained (2,109.2 ± 139.6 N) and multiunit screw-retained abutments (3,319.4 ± 218.9 N). Conclusion: Screw-retained implant-supported FPDs withstand higher occlusal forces compared with cement- and multiunit screw-based retention techniques. However, the results should be cautiously interpreted, as they were based on a relatively small sample size. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this in vitro study was to evaluate the mechanical behavior regarding dynamic fatigue of different implant-abutment connections and the unitary indication of abutments for all regions of the mouth. Materials and Methods: This experimental study developed according to international standards (ISO 14801:2007) was performed using five types of implants and abutments: G1--external hex smart implant and 17-degree universal abutment (EHS); G2--cortical external hex implant and 17-degree universal abutment (EHTi); G3--internal hex implant and 30-degree universal abutment (IH); G4--Morse taper implant (11.5 degrees) and 17-degree universal abutment (MT11.5); and G5--Morse taper implant (16 degrees) and 30-degree universal abutment (MT16). A 15-Hz cyclic loading was applied to the specimens with the maximum number of cycles set at 5 x 106. Success was defined when three samples supported 5 million cycles without failure. The maximum load supported from each group after dynamic loading was recorded. The Spearman correlation and the Lowess method were used to analyze the correlation between the number of cycles and the applied load, and the Kruskal-Wallis and Nemenyi tests were used for comparison between the abutments when reaching 5 million cycles. Results: There was a negative correlation (r < 0.00) and significant difference (P < .05) between the number of cycles and the load for each type of implant and abutment. The load values supported by each group after cyclic loading to achieve 5 million cycles were as follows: EHS, 225 N; EHTi, 215 N; IH, 220 N; MT11.5, 210 N; and MT16, 240 N. The MT16 implant-abutment assembly presented a significantly higher load (P = .024) than the MT11.5 implant-abutment assembly. Conclusion: All implant-abutment connections investigated in this study resisted average occlusal force values reported as acceptable in the literature and may be indicated for any region of the mouth. [ABSTRACT FROM AUTHOR]

Local scour around bridge piers and abutments is one of the most significant causes of bridge failure. Despite a plethora of studies on scour around individual bridge piers or abutments, few studies have focused on the joint impact of a pier and an abutment in proximity to one another on scour. This study conducted laboratory experiments and flow analyses to examine the interaction of piers and abutments and their effect on clear-water scour. The experiments were conducted in a rectangular laboratory flume. They included 18 main tests (with a combination of different types of piers and abutments) and five control tests (with individual piers or abutments). Three pier types (a rectangular pier with a rounded edge, a group of three cylindrical piers, and a single cylindrical pier) and two abutment types (a wing–wall abutment and a semi-circular abutment) were used. An acoustic Doppler velocimeter was used to measure the three-dimensional flow velocity for analyses of streamline, velocity magnitude, vertical velocity, and bed shear stress. The results showed that the velocity near the pier and abutment increased by up to 80%. The maximum scour depth around the abutment increased by up to 19%. In contrast, the maximum scour depth around the pier increased significantly by up to l71%. The presence of the pier in the vicinity of the abutment led to an increase in the scour hole volume by up to 87% relative to the case with a solitary abutment. Empirical equations were also derived to accurately estimate the maximum scour depth at the pier adjacent to the abutment.

The use of titanium as a biomaterial for the treatment of dental implants has been successful and has become the most viable and common option. However, in the last three decades, new alternatives have emerged, such as polymers that could replace metallic materials. The aim of this research work is to demonstrate the structural effects caused by the fatigue phenomenon and the comparison with polymeric materials that may be biomechanically viable by reducing the stress shielding effect at the bone–implant interface. A numerical simulation was performed using the finite element method. Variables such as Young’s modulus, Poisson’s coefficient, density, yield strength, ultimate strength, and the S-N curve were included. Prior to the simulation, a representative digital model of both a dental implant and the bone was developed. A maximum load of 550 N was applied, and the analysis was considered linear, homogeneous, and isotropic. The results obtained allowed us to observe the mechanical behavior of the dental implant by means of displacements and von Mises forces. They also show the critical areas where the implant tends to fail due to fatigue. Finally, this type of non-destructive analysis proves to be versatile, avoids experimentation on people and/or animals, and reduces costs, and the iteration is unlimited in evaluating various structural parameters (geometry, materials, properties, etc.).