Influence of building direction on physical and mechanical properties of titanium implants: A systematic review.

The objective of the systematic review is to find an answer to a question: "What is the influence of the building direction of titanium implants produced by additive manufacturing on their physical and mechanical properties?" This review followed the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA 2020) and was registered in the Open Science Framework (OSF) (osf.io/rdc84). Searches were performed in PubMed, Scopus, Science Direct, Embase, and Google Scholar databases on February 17th, 2024. Articles were chosen in 2 steps by 2 blinded reviewers based on previously selected inclusion criteria: In vitro studies that evaluated the influence of the impression direction of titanium implants produced by additive manufacturing on their physical and mechanical properties were selected. Articles were excluded that (1) did not use additive technology to obtain the implants, 2) used surfaces other than titanium, 3) did not evaluate the direction of impression, 4) Studies with only in vivo analyses, clinical studies, systematic reviews, book chapters, short communications, conference abstracts, case reports, and personal opinions.). In the initial search, 581 results were found. Of this total, 108 were excluded for duplication and, after applying the eligibility criteria, 16 articles were included in the present review. The risk of bias was analyzed using the RoBDEMAT. The risk of bias was analyzed using the RoBDEMAT. In addition, the coefficient of interagreement of the reviewers (Cohen's Kappa) and the certainty of evidence by GRADE were analyzed. In general, different impression angles showed variations in the physical and mechanical characteristics of the groups evaluated, including roughness, tensile strength, hardness, and modulus of elasticity. While some impression orientations resulted in greater strength or hardness, others showed greater elasticity or lower surface roughness. These findings suggest that print orientation plays a significant role in determining material properties. It can be concluded that printing directions influence the physical and mechanical properties of titanium implants and the studies included showed that the 0°, 45°, and 90° directions are the most evaluated as they present lower probabilities of structural anisotropies and provide better results in their roughness, hardness, tensile and compressive strength.

Comparative analysis of the physical, chemical, and microbiological properties of Ti-6Al-4V disks produced by different methods and subjected to surface treatments.

STATEMENT OF PROBLEM: To improve the osseointegration of dental implants and reduce microbiological growth, different micro- and nanoscale surface topographies can be used. PURPOSE: The purpose of this in vitro study was to evaluate the influence of Ti-6Al-4V with 4 surfaces, machined (DU), machined+hydroxyapatite (DUHAp), machined+acid-alkali treatment (DUAA), and additive manufacturing (DMA), on the physical, chemical, and microbiological properties. MATERIAL AND METHODS: The topography of Ti-6Al-4V disks with the 4 surfaces was evaluated by scanning electron microscopy (SEM), the chemical composition by energy dispersive X-ray spectroscopy (EDS), and the crystalline structure by X-ray diffraction (XRD). Physical and chemical properties were analyzed by using wettability and surface free energy, roughness, and microbial adhesion against Staphylococcus aureus by colony forming units (CFU). One-way ANOVA analysis of variance and the Tukey multiple comparisons test were applied to evaluate the data, except CFU, which was submitted to the Kruskal-Wallis nonparametric test (α=.05). RESULTS: DU photomicrographs showed a topography characteristic of a polished machined surface, DUHAp and DUAA exhibited patterns corresponding to the surface modifications performed, and in DMA the presence of partially fused spherical particles was observed. The EDS identified chemical elements inherent in the Ti-6Al-4V, and the DUHAp and DUAA disks also had the ions from the treatments applied. XRD patterns revealed similarities between DU and DMA, as well as characteristic peaks of hydroxyapatite (HA) in the DUHAp disk and the DUAA. Compared with DU and DMA the DUHAp and DUAA groups showed hydrophilic behavior with smaller contact angles and higher surface free energy (P<.05). DMA showed a higher mean value of roughness, different from the others (P<.05), and a higher CFU for S. aureus (P=.006). CONCLUSIONS: DUHAp and DUAA showed similar behaviors regarding wettability, surface free energy, and bacterial adhesion. Among the untreated groups, DMA exhibited higher roughness, bacterial adhesion, and lower wettability and surface free energy.

Artificial teeth obtained by additive manufacturing: Wear resistance aspects. A systematic review of in vitro studies.

Wear resistance is one of the properties that must be considered for maintaining the long-term functionality of artificial teeth in dental prostheses. This property can be altered by the method of tooth fabrication, the material, the chewing force, and the relationship to the antagonist tooth. This systematic review evaluated the wear resistance of artificial teeth obtained by the additive manufacturing method and aims to answer the question, "Do artificial teeth for dental prostheses obtained by additive manufacturing show wear resistance similar to prefabricated ones?" The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Checklist guidelines were followed with a customized search in Scopus, PubMed/Medline, Embase, Science Direct, and Google Scholar databases on August 30, 2023. The inclusion criteria were artificial teeth for dental prostheses in acrylic resin by additive manufacturing and comparing the wear resistance with conventional prefabricated teeth, in vitro and English studies, without time restriction. And excluded if 1) do not make artificial teeth by additive manufacturing or that were metal or ceramic teeth; 2) clinical trials, animal studies, review articles, case reports, letters to the editor, short communication, book chapters; 3) another language that is not English. The selection was in two steps, reading the titles and abstracts, followed by reading the selected studies in full. The risk of bias analysis was performed with the adaptation of the quasi-experimental studies tool by Joanna Briggs Institute. Four hundred and twelve articles were found in the databases, after the selection steps and application of eligibility criteria, 6 articles were included for qualitative data analysis and presented low risk of bias. For teeth obtained by additive manufacturing, 2 studies reported lower wear resistance, 2 studies had higher resistance, and 2 similar compared to prefabricated ones. Additive manufactured teeth compared to prefabricated teeth show influences on wear resistance due to differences in material composition, relationship to the antagonist's tooth, applied force, chewing cycles, and processing methods.

Osseointegration in additive-manufactured titanium implants: A systematic review of animal studies on the need for surface treatment.

The objective of the systematic review is to find an answer to a question: "Do surface treatments on titanium implants produced by additive manufacturing improve osseointegration, compared to untreated surfaces?". This review followed the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA 2020) and was registered in the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42022321351). Searches were performed in PubMed, Scopus, Science Direct, Embase, and Google Scholar databases on March 22nd, 2022. Articles were chosen in 2 steps by 2 blinded reviewers based on previously selected inclusion criteria: articles in animals that addressed the influence of surface treatments on osseointegration in implants produced by additive manufacturing. Articles were excluded that (1) did not use titanium surface, 2) that did not evaluate surface treatments, 3) that did not described osseointegration, 4) Studies with only in vitro analyses, clinical studies, systematic reviews, book chapters, short communications, conference abstracts, case reports and personal opinions.). 1003 articles were found and, after applying the eligibility criteria, 17 were used for the construction of this review. All included studies found positive osseointegration results from performing surface treatments on titanium. The risk of bias was analyzed using the SYRCLE assessment tool. Surface treatments are proposed to promote changes in the microstructure and composition of the implant surface to favor the adhesion of bone cells responsible for osseointegration. It is observed that despite the benefits generated by the additive manufacturing process in the microstructure of the implant surface, surface treatments are still indispensable, as they can promote more suitable characteristics for bone-implant integration. It can be concluded that the surface treatments evaluated in this systematic review, performed on implants produced by additive manufacturing, optimize osseointegration, as it allows the creation of a micro-nano-textured structure that makes the surface more hydrophilic and allows better contact bone-implant.

Effect of pores on cell adhesion to additively manufactured titanium implants: A systematic review.

STATEMENT OF PROBLEM: Titanium dental implants produced by additive manufacturing have pores that, depending on their size and quantity, may improve osteogenic cell adhesion without impairing mechanical properties. A systematic review of in vitro studies on this topic is lacking. PURPOSE: The purpose of this systematic review was to answer the question "What is the influence of pores on osteogenic cell adhesion on titanium surfaces produced by additive manufacturing?". MATERIAL AND METHODS: The study was designed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) 2020 standards and registered in the Open Science Framework (OSF) (osf.io/baw59). A manual search of published articles without language or time restrictions was conducted in November 2022 in the electronic databases PubMed, Scopus, ScienceDirect, Embase, and in the nonpeer-reviewed literature via Google Scholar. RESULTS: A total of 1338 initial results were found, and after removing duplicates and applying eligibility criteria, 13 articles were included in this review that, according to the Joanna Briggs Institute (JBI) tool, presented a low risk of bias. Pores with larger diameters provide greater a surface area that favors cell filopodia adhesion and has interconnection that optimizes the transport of nutrients and oxygen and bone cell activity. CONCLUSIONS: The presence of pores on the surface of titanium produced by additive manufacturing increases the adhesion, migration, proliferation, and viability of osteogenic cells.

Protein absorption on titanium surfaces treated with a high-power laser: A systematic review.

STATEMENT OF PROBLEM: The surface of titanium dental implants treated with a high-power laser has been reported to favor osseointegration, mainly by altering protein uptake. Despite the large number of articles that address the topic, the heterogeneity of methodologies and results makes an understanding of the treatment's benefits difficult, and a systematic review is needed. PURPOSE: The purpose of this systematic review was to further the knowledge on protein uptake on titanium surfaces that have undergone treatment with a high-power laser. MATERIAL AND METHODS: This review followed the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines and was registered with the Open Science Framework (OSF) (osf.io/gcbna). Searches were performed in PubMed, Scopus, Web of Science, Embase, and Google Scholar databases. The articles were selected in 2 steps by 2 independent reviewers according to the previously selected eligibility criteria. The risk of bias was analyzed by using the Joanna Briggs Institute (JBI)-adapted quasi-experimental study evaluation tool. RESULTS: The studies addressed have shown that applying a high-power laser to the implant surface, depending on its settings, generates topographical changes that can optimize the protein absorption process and thus accelerate the other biological processes. CONCLUSIONS: The studies identified in this systematic review showed that surface treatment with a high-power laser represents a promising technique with a positive influence on protein uptake and osseointegration.