Search Results (52)

Background/Objectives: The utility of various biocompatible biological and synthetic polymers as substrates to provide structural support, facilitate cell migration, and promote the healing of full-thickness wounds by secondary intention has been studied. This includes intelligent structures that enable the release of natural products or drugs for these and other purposes. In this study, the primary objective was to analyze and compare, from a macroscopic perspective, the individual behavior of the polymer poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), with Aloe vera (PHBV/Av) or honey (PHBV/Ho), in the healing process of a full-thickness skin wound over 40 days in a murine model, in addition to describing the microscopic ultrastructure of the nanofibers. Methods: Two experimental groups were established, PHVB/AV (n = 5) and PHVB/Ho (n = 5), along with one control group, PHBV (n = 5), all of which underwent biopsies that included the entire thickness of the skin and the panniculus carnosus of the mid-dorsal area of the mouse. Cylindrical pieces of each membrane, measuring approximately 7 × 0.2 mm, were placed in the wound bed and covered with a transparent dressing. No topical treatment was administered during the control process, nor were the implants changed during the healing period. Results: Univariate and multivariate analyses were performed. The data show that the PHBV/Ho scaffolds reduce the diameter of the wounds by 100% after 40 days (p < 0.001), compared with PHBV/Av (100%; p = 0.211) and the control group, PHBV. Conclusions: From a macroscopic perspective, the PHBV/Ho scaffold significantly accelerated wound healing when applied once to the wound bed, outperforming both the PHBV/Av composite and PHBV alone. Notably, this effect was achieved without the need for dressing changes or additional treatment during the healing period. Full article

Background/Objectives: Surgical guides have been used in a variety of dental procedures, such as implant placement to improve clinical accuracy and reduce post-operative complications. This report presents a novel and versatile workflow for the design and fabrication of a “multi-purpose” fully-guided tooth- and bone-supported one-piece surgical guide. Methods: Briefly, intraoral and perioral anatomical features were captured by an intraoral scan and a cone-beam computed tomography scan. The data were segmented and aligned with analysis software to enable the digital design of surgical guides. The versatility of this method was demonstrated through its application in the two cases presented: the first involved a lateral sinus lift with simultaneous implant placement, and the second involved the removal of a foreign object from the alveolar bone prior to implant placement. Results: Positive clinical outcomes were confirmed at follow-up visits for up to 12 months. Conclusions: This method may be applied to a range of challenging clinical scenarios, such as apicectomy, the extraction of supernumerary or unerupted teeth, corticotomy to facilitate orthodontic movement, the precise reduction of bony spurs or exostoses, and the conservative surgical removal of pathologies. Full article

Objectives: CAD-CAM technology has enabled clinicians to provide accurate and predictable restorations. Chairside time has been reduced and patient’s comfort has been improved. A fully digital workflow can be now predictably adopted in implant surgery and implant restorations. Methods: A male patient, 55 years old, was referred for the restoration of his edentulous mandible. Radiographs and clinical evaluation were assembled to plan implant placement. The flapless approach is preferred to provide for a mucosa-supported surgical guide and lessen the patient’s post-operative complications. In flapless cases, the operator does not have any direct overview of the surrounding soft tissues and underlying bone. In this case, a new, minimally invasive H-shaped incision technique was performed. A fully digital protocol is presented with a two-piece stackable surgical guide to confirm accurate implant placement. Results: A high-performance polymer framework (PEEK) combined with zirconia crowns completes the digitally designed edentulous restoration. Conclusions: Adopting this technique offers the clinician benefits in both the surgical and the restorative part. Full article

Prestressed, precast composite panels are a type of building component that combines prestressing technology with composite materials; but, for most of them, it is difficult to balance structural stress performance and assembly efficiency. This paper proposes a series of novel bidirectional, prestressed, prefabricated, composite slabs, aiming to enhance their bidirectional force characteristics and assembly efficiency. By implanting a kind of specially designed concrete movable core rib with the same geometry as the cavity in the hollow-core slab at medium spacing, the transverse stressing performance of the structure is enhanced without affecting the unidirectional structural performance. Then, in the pre-set transverse apertures, several pieces of unidirectional, prestressed, precast hollow-core slabs that are implanted in the core mold are connected in series with high-strength strands and prestressed; finally, we obtain a bidirectional, prestressed, prefabricated composite slab. Two types of slabs (i.e., 3.3 m × 4.5 m and 4.5 m × 4.5 m) are selected and their mechanical behavior is investigated experimentally and by the finite element method, and the results are in good agreement. The proposed bidirectional, prestressed, precast composite slab not only has better overall bearing performance but also improves the structural stiffness and assembly rate, which can greatly improve the economic benefits and is of great significance for the popularization and application of assembled concrete structures. Full article

The widely available options of different manufacturers in dental implant systems have complicated the selection criteria process for periodontists, necessitating careful consideration of various factors when selecting suitable solutions for individual patient needs. Optimal implant selection requires careful consideration of the patient-specific factors, implant design, and surgical technique. Understanding the biomechanical behavior of implant–tissue interactions is crucial for achieving successful and long-lasting implant therapy. To adequately address this issue and improve the rigorous selection criteria from a biomechanically numerical approach, this research aims to analyze the stress distribution fields, strain patterns, and load transfer displacements within the implant system and the implant–biological interface (gingival and bony tissues) of titanium three-piece to two–one-piece ceramic implant systems. Thus, three different commercially available dental implants designed to be placed in the jaw molar region were considered for evaluation through the finite element method under both oblique and occlusal loading conditions. The results have exhibited an increasing trend to highlight the outstanding behavior of two-piece ceramic implants to dissipate the stress distribution better (6 and 2 times lower than the three- and one-piece systems under occlusal loads and almost 5 and 1.3 times more efficient for oblique loading, respectively), minimize peak stress values (below 100 MPa), and reduce strain peak patterns compared with the other two evaluated designs. On the other hand, the effects generated in biological tissues are strongly associated with implant geometry features. This biomechanical approach could provide a promising strategy for predicting micro-strains and micromotion in implant system pieces and geometries. Hence, these findings contribute to a deeper understanding of the biomechanics spectrum in the behavior of dental implant systems and emphasize the importance of carefully selecting appropriate material systems for accurate patient-specific biomechanical performance. Full article

The study reviewed the state of the art of the clinical use of a convergent-neck-designed Prama implant. This implant was introduced approximately 10 years ago and was characterized by a specific and unique convergent neck with a microtextured surface (UTM surface) and Zirconium Titanium (ZirTi) implant body surface. The neck design was developed to adopt the biologically oriented preparation technique (BOPT). A critical analysis of the published clinical studies and an evaluation of the adopted clinical protocols were performed. A total of forty-six articles were eligible to be reviewed. Only sixteen clinical studies reported clinical outcomes on Prama implants, and nine of these were selected having the longest follow-up from different research groups. The clinical follow-up/duration of the studies ranged from 12 months to 6 years. The initially proposed protocols explored neck supracrestal–transmucosal placement and gained interest due to its minimally invasive concept and the ability to proceed without a pre-prosthesis second surgery. The following investigations dedicated attention to the subcrestal or equicrestal implant placement with the conventional flap approach. The clinical studies characterized by the transmucosal exposed neck approach reported high survival rates with a stable bone morphology and reduced bone loss during the follow-up. Further recent implementations included the introduction of different convergent neck heights that need to be evaluated. The use of intraoral scanner technologies and digital workflow resulted in a simpler methodology with control of the marginal crown morphology. The studies support the concept that the hard tissue parameters (such as marginal bone level, MBL) and soft tissue parameters (such as pink esthetic score, PES) were stable or improved during the follow-up. Definitive crowns, designed with low invasiveness for soft tissues, were possible thanks to the morphology of the neck. The clinical studies support the use of the Prama implant with the different neck positions, demonstrating hard tissue preservation and optimal esthetic results in the first years following insertion. However, the current body of evidence is not robust enough to draw definitive conclusions, especially in the long term, and further high-quality research (long-term randomized trials) is required to consolidate these early observations. Full article

Implant abutments are essential components of implant prosthetic restorations. The golden standard for abutment material is titanium; however, due to its properties, the esthetic result can be compromised. The most popular esthetic material alternatives are one- and two-piece zirconia. The study aimed to answer the questions of whether zirconia abutments can be used interchangeably with titanium in both anterior and posterior regions and how aging of the abutment affects durability. For this study, an electronic search of MEDLINE (PubMed) and Scopus (Embase) was conducted. The PRISMA guidelines were followed, and a systematic review was registered with PROSPERO. The search revealed 4031 results, of which 17 studies were selected. The strongest material for abutments is titanium, closely followed by two-piece zirconia. One-piece zirconia abutments were the weakest. The cyclic loading above 1,000,000 cycles decreased the fracture resistance of the abutments. Differences in implant diameter, angulation, and restoration affected the fracture strength of all compared materials. The main mode of failure for titanium abutments was screw bending or screw fracture. One-piece zirconia most often presented catastrophic failure with internal hexagon fracture below the implant neck. Two-piece zirconia exhibits a combination of failure modes. Two-piece zirconia abutments may be suitable for use in the posterior region, given their comparable fracture resistance to titanium abutments. Despite the fact that one-piece zirconia is capable of withstanding forces that exceed those exerted during mastication, it is recommended that it be employed primarily in the anterior dentition due to its propensity for unfavorable failure modes. Full article

Objectives: This study compared long-term surgical outcomes of the scleral flap versus scleral pocket technique for sutureless intrascleral one-piece intraocular lens (IOL) fixation. Methods: A retrospective comparative study was conducted at a single center, involving consecutive patients undergoing sutureless intrascleral one-piece IOL implantation, between January 2020 and May 2022. Eyes were divided into two groups based on the surgical technique: group 1 underwent scleral flap (n = 64), and group 2 received scleral pocket technique (n = 59). Visual acuity, refractive outcomes, and complications were assessed over a minimum 24-month follow-up period. Results: Both groups showed improvements in best-corrected visual acuity (BCVA), increasing from 0.84 ± 0.56 logMAR at baseline to 0.39 ± 0.23 logMAR (p = 0.042) at 24 months in group 1 and from 0.91 ± 0.63 logMAR at baseline to 0.45 ± 0.38 logMAR (p = 0.039) at 24 months in group 2. No significant differences in BCVA were observed between the groups at baseline (p = 0.991), 12 (p = 0.496) and 24 months (p = 0.557). Mean spherical equivalent (−0.73 ± 1.32 D in group 1 and −0.92 ± 0.99 D in group 2, p = 0.447), refractive prediction error (−0.21 ± 1.1 D in group 1 and −0.35 ± 1.8 D in group 2, p = 0.377), and surgically induced astigmatism (0.74 ± 0.89 D in group 1 and 0.85 ± 0.76 in group 2, p = 0.651) were comparable between the two groups. An IOL tilt of 5.5 ± 1.8 and 5.8 ± 2.0 degrees (p = 0.867) and an IOL decentration of 0.41 ± 0.21 mm and 0.29 ± 0.11 mm (p = 0.955) were obtained, respectively, in group 1 and group 2 at 24 months. Mean endothelial cell density remained stable at 24 months in both groups (p = 0.832 in group 1 and p = 0.443 in group 2), and it was 1747.20 ± 588.03 cells/mm² in group 1 and 1883.71 ± 621.29 cells/mm² in group 2 (p = 0.327) at baseline, 1545.36 ± 442.3 cells/mm² in group 1 and 1417.44 ± 623.40 cells/mm² in group 2 (p = 0.483) at 24 months. No cases of endophthalmitis were observed. Conclusions: The scleral pocket technique for sutureless intrascleral one-piece IOL fixation is comparable to the traditional scleral flap technique in terms of long-term visual outcomes and safety. The scleral pocket technique offers a simplified approach and a viable option even for less experienced surgeons. Full article

This study evaluates the dynamic shift in the microbiota at the peri-implant site of titanium (Ti) and zirconia (Zr) implants subjected to experimental peri-implantitis (PI) and, for the first time, of implants made of ceria-stabilized alumina-reinforced zirconia (Ce-TZP/Al), a revolutionary zirconia that is set to play a key role in modern implant dentistry. One- and two-piece (TP) implants, including Ce-TZP/AL TP/G3 glass, were placed bilaterally (six implants/side) in five beagle dogs to mimic a natural vs. ligature-induced PI following a split-mouth design. The experiment spanned 30 weeks from tooth extraction. Both PI models promoted plaque deposition at peri-implant sites. Comparatively, the PI induced by ligatures favored the deposition of anaerobes (p = 0.047 vs. natural). Regardless of the model, the plaque deposition pattern was entirely dependent on the implanted material. Ligated Ti and Zr implant sites accumulated up to 2.14 log CFU/mL unit anaerobic load (p ≤ 0.033 vs. non-ligated implant sites), predominantly comprising obligate anaerobes. Naturally occurring PI induced the deposition of co-occurring networks of obligate anaerobes and less oxygen-dependent bacteria. PI induction favored the enrichment of Ti and Zr sites with bacterial taxa belonging to the orange and red complexes (up to 28% increase naturally and up to 71% in the ligated hemiarch). Anaerobic deposition was significantly lower in ligated Ce-TZP/Al implant sites (p ≤ 0.014 vs. TI and Zr) and independent of the induction model (0.63–1 log units of increase). Facultative bacteria prevailed at Ce-TZP/AL sites. The abundance was lower in the Ce-TZP/AL TP implant. Unlike Ti and Zr sites, taxa from the orange and red complexes were negligible. Biofilms configured at the Ti and Zr sites after ligation-induced PI resemble those found in severe IP. We hypothesize that, although surface properties (surface energy and surface roughness) and physicochemical properties of the substrate play an important role in bacterial adhesion and subsequent plaque formation, Ce-TZP/Al modulates several biological activities that preserve the integrity of the gingival seal by limiting PI progression. In conclusion, biofilm progression differs in peri-implant sites according to the specific properties of the material. Ce-TZP/A, unlike titanium or zirconia, prevents dysbiosis in sites subjected to experimental PI and preserves the microbial signature of emergent obligate anaerobes related to PI development. Full article

Preclinical and clinical research on two-piece zirconia implants are warranted. Therefore, we evaluated the in vitro fracture resistance of such a zirconia oral implant system. The present study comprised 32 two-piece zirconia implants and abutments attached to the implants using a titanium (n = 16) or a zirconia abutment screw (n = 16). Both groups were subdivided (n = 8): group T-0 comprised implants with a titanium abutment screw and no artificial loading; group T-HL was the titanium screw group exposed to hydro-thermomechanical loading in a chewing simulator; group Z-0 was the zirconia abutment screw group with no artificial loading; and group Z-HL comprised the zirconia screw group with hydro-thermomechanical loading. Groups T-HL and Z-HL were loaded with 98 N and aged in 85 °C hot water for 10⁷ chewing cycles. All samples were loaded to fracture. Kruskal–Wallis tests were executed to assess the loading/bending moment group differences. The significance level was established at a probability of 0.05. During the artificial loading, there was a single occurrence of an implant fracture. The mean fracture resistances measured in a universal testing machine were 749 N for group T-0, 828 N for group Z-0, 652 N for group T-HL, and 826 N for group Z-HL. The corresponding bending moments were as follows: group T-0, 411 Ncm; group Z-0, 452 Ncm; group T-HL, 356 Ncm; and group Z-HL, 456 Ncm. There were no statistically significant differences found between the experimental groups. Therefore, the conclusion was that loading and aging did not diminish the fracture resistance of the evaluated implant system. Full article

The modern approach to the recovery of damaged and missing bone tissue is increasingly focused on the application of implants capable of supporting the growth and recovery of parent tissue, rather than replacing the tissue itself. In this regard, the primary task of modern bone implants is to enable the targeted deformation of the implant against the expected load that that piece of bone should bear. The paper presents research related to anatomically shaped lattice scaffolds (ASLSs) made by the direct metal laser sintering (DMLS) of Ti-6Al-4V powder, and refers to the influence of the crossing angle between the outer lattice struts on the rigidity of the scaffold structure. The study includes the measurement of the deformation of two ASLSs designed for the same missing piece of rabbit tibia; these differed in terms of the crossing angle of the struts in the outer lattice and were exposed to quasi-uniaxial compression. The results show that the ASLS with outer struts that intersect at 60° (the angle between the compression direction and the strut axes is 30°) is more flexible compared to the ASLS with outer struts that intersect at 90° (the compression direction and the strut axes are colinear), even though its porosity is lower and volume is bigger. Full article

The purpose of the present study was to assess the fracture resistance of a two-piece alumina-toughened zirconia implant system with a carbon-reinforced PEEK abutment screw. Methods: Thirty-two implants with screw-retained zirconia abutments were divided into four groups of eight samples each. Group 0 (control group) was neither loaded nor aged in a chewing simulator; group H was hydrothermally aged; group L was loaded with 98 N; and group HL was subjected to both hydrothermal aging and loading in a chewing simulator. One sample of each group was evaluated for t-m phase transformation, and the others were loaded until fracture. A one-way ANOVA was applied to evaluate differences between the groups. Results: No implant fracture occurred during the artificial chewing simulation. Furthermore, there were no statistically significant differences (p > 0.05) between the groups in terms of fracture resistance (group 0: 783 ± 43 N; group H: 742 ± 43 N; group L: 757 ± 86 N; group HL: 740 ± 43 N) and bending moment (group 0: 433 ± 26 Ncm; group H: 413 ± 23 Ncm; group L: 422 ± 49 Ncm; group HL: 408 ± 27 Ncm). Conclusions: Within the limitations of the present investigation, it can be concluded that artificial loading and hydrothermal aging do not reduce the fracture resistance of the investigated implant system. Full article

Purpose: To evaluate the performance of traditional vergence formulas with segmented axial length (AL) compared to traditional composite AL in extremely long eyes, and to determine whether the segmented AL can be extended to the new-generation formulas, including the Barrett Universal II, Emmetropia Verifying Optical 2.0 (EVO2), Hill-RBF 3.0 (Hill3), Kane, and Ladas Super formula (LSF) formulas in extremely long eyes. Setting: National Hospital. Organization, Tokyo Medical Center, Japan. Design: Retrospective case series. Methods: Consecutive patients who underwent uncomplicated cataract surgery implanted with a three-piece intraocular lens between December 2015 and March 2021 were retrospectively reviewed. The composite AL was measured with a swept-source optical coherence tomography (SS-OCT) biometer using a mean refractive index. The segmented AL was calculated by summing the geometric lengths of the ocular segments (cornea, aqueous, lens, and vitreous) using multiple specific refractive indices based on the data obtained by the SS-OCT-based biometer. When refraction was measured at three months postoperatively, the median absolute errors (MedAEs) were calculated with two ALs for each formula. Results: The study included 31 eyes of 22 patients. The segmented AL (30.45 ± 1.23 mm) was significantly shorter than the composite AL (30.71 ± 1.28 mm, p < 0.001). The MedAEs were significantly reduced when using segmented AL for SRK/T, Haigis, Hill3, and LSF, compared to those obtained using composite AL (0.38 vs. 0.62, 0.48 vs. 0.79, 0.50 vs. 0.90, 0.34 vs. 0.61, p < 0.001 for all formulas, respectively). On the contrary, the MedAE obtained by Kane with segmented AL was significantly worse compared to the one with composite AL (0.35 vs. 0.27, p = 0.03). Conclusion: In extremely high myopic eyes, the segmented AL improves the performance of SRK/T, Haigis, Hill3, and LSF formulas compared to the composite AL, while the segmented AL worsens the prediction accuracy of the Kane formula. Full article

Background: The purpose of this in vitro study was to compare the inter-implant distance, inter-implant axis, and intra-implant axis of three implants in a straight line by using a laboratory scanner (LBS) versus an intra-oral scanner (IOS) with two different intra-oral scan bodies (ISBs). Methods: A 3D model was printed with internal hex implant analogs of three implants in positions 15#, 16#, and 17#. Two standard intra-oral scan bodies (ISBs) were used: MIS ISB (two-piece titanium) and Zirkonzhan ISB (two-piece titanium). Both ISBs were scanned using 7 Series dental wings (LBS) and 30 times using Primescan (IOS). For each scan, a stereolithography (STL) file was created and a comparison between all the scans was performed through superimposition of the STL files by using 3D analysis software (PolyWorks^® 2020; InnovMetric, Québec, QC, Canada). A Kolmogorov–Smirnov test was performed followed by a Mann–Whitney test (p < 0.05). Results: The change in inter-implant distance for the MIS ISB was significantly lower compared to the ZZ (p < 0.05). The change in intra-implant angle was significantly lower for the ZZ ISB compared to MIS (p < 0.05). The changes in inter-implant angle between the mesial and middle and between the middle and distal were significantly lower for MIS compared to ZZ in contrast to mesial to distal, which was significantly higher (p < 0.05). Conclusions: Both ISBs showed differences in all the parameters between the LBS and the IOS. The geometry of the scan abutment had an impact on the inter-implant distance as the changes in the inter-implant distance were significantly lower for the MIS ISB. The changes in the intra-implant angle were significantly lower for the ZZ ISB. There is a need for further research examining the influence of geometry, material, and scan abutment parts on the trueness. Full article

This study investigated the effects of antirotational titanium bases on the mechanical behavior of CAD/CAM titanium bases used for implant-supported prostheses. The aim was to assess the impact on the marginal fit, fatigue behavior, stress concentration, and fracture load of implant-supported CAD/CAM zirconia crowns. Forty titanium implants were divided into two groups: those with antirotational titanium bases (ARs) and those with rotational titanium bases (RTs). Torque loosening and vertical misfit were evaluated before and after cyclic fatigue testing (200 N, 2 Hz, 2 × 10⁶ cycles). Fracture resistance was assessed using a universal testing machine (1 mm/min, 1000 kgf), and failed specimens were examined with microscopy. Three-dimensional models were created, and FEA was used to calculate stress. Statistical analysis was performed on the in vitro test data using two-way analysis of variance and Tukey’s test (α = 0.5). Results show that the presence of an antirotational feature between the implant and titanium base reduced preload loss and stress concentration compared to rotational titanium bases. However, there were no differences in vertical misfit and resistance to compressive load. Full article