Search Results (115)

Background: Prosthetic cementation using the biologically oriented preparation technique (BOPT) presents challenges in removing excess cement from the gingival sulcus, due to the absence of a finishing line and the impossibility of using absolute isolation with a rubber dam. This study aimed to evaluate the effectiveness of relative isolation using polytetrafluoroethylene (PTFE) tape in reducing cement retention during BOPT cementation. Methods: Fifteen 3D-printed resin models were created from an intraoral scan of a patient restored with BOPT in both upper central incisors. Each model included removable gingiva. Splinted polymethylmethacrylate (PMMA) provisional crowns were fabricated and cemented with temporary cement. One central incisor was isolated with PTFE (0.1 mm or 0.2 mm), while the contralateral tooth was left unisolated as a control. After debonding, digital scanning and volumetric analysis using root mean square (RMS) deviation were performed to quantify retained cement. Paired t-tests were applied to compare groups. Results: The mean RMS for the PTFE group was 0.1248 ± 0.0519 mm, compared to 0.1973 ± 0.0361 mm in the non-isolated group (p < 0.001). No significant difference was found between PTFE thicknesses of 0.1 mm and 0.2 mm (p = 0.388). Conclusions: PTFE tape is effective for relative isolation when rubber dam placement is not feasible in BOPT restorations. Further clinical studies are recommended to confirm these findings in vivo. Full article

This study reports the impact of a silver nanoparticles/reduced graphene oxide@titanium dioxide nanocomposite (Ag/rGO@TiO₂) on the mechanical and biocompatibility properties of poly(styrene-co-methylmethacrylate)/poly methyl methacrylate (PS-PMMA/PMMA)-based bone cement. The chemical, structural, mechanical, and thermal characteristics of Ag/rGO@TiO₂ nanocomposite-reinforced PS-PMMA bone cement ((Ag/rGO@TiO₂)/(PS-PMMA)/PMMA) were evaluated using Fourier Transform Infrared spectroscopy (FT-IR), X-ray diffraction (XRD), nano-indentation, and electron microscopy. FT-IR, XRD, and transmission electron microscopy results confirmed the successful synthesis of the nanocomposite and the nanocomposite-incorporated bone cement. The elastic modulus (E) and hardness (H) of the ((Ag/rGO@TiO₂)/(PS-PMMA)/PMMA) bone cement were measured to be 5.09 GPa and 0.202 GPa, respectively, compared to the commercial counterparts, which exhibited E and H values of 1.7 GPa to 3.7 GPa and 0.174 GPa, respectively. Incorporating Ag/rGO@TiO₂ nanocomposites significantly enhanced the thermal properties of the bone cement. Additionally, in vitro studies demonstrated that the bone cement was non-toxic to the MG63 cell line. Full article

Poly(methyl methacrylate) (PMMA)-based bone cements are widely used in orthopaedic surgery, yet their inherent brittleness, lack of bioactivity, and exothermic polymerization remain critical limitations. Recent strategies have focused on modifying PMMA with functional additives to improve not only mechanical performance but also thermal behaviour and biological interactions. This study investigates the mechanical properties of two commercial PMMA cements—Palamed^® (antibiotic-free) and Refobacin Plus G (gentamicin-loaded)—reinforced with glassy carbon (GC) particles of two different grain sizes (0.4–1.2 µm and 20–50 µm) and various concentrations. The results demonstrate that coarse GC particles (20–50 µm) significantly reduced compressive strength, particularly in the antibiotic-loaded cement. In contrast, the incorporation of fine GC particles (0.4–1.2 µm) did not markedly impair mechanical performance in Palamed^®, suggesting better compatibility with the PMMA matrix. In addition to mechanical enhancement, the structural and chemical stability of glassy carbon may contribute to improved biological response and reduced polymerization heat. These findings highlight the potential of glassy carbon as a functional additive for designing PMMA-based biomaterials that combine improved mechanical properties with favourable characteristics for long-term implant integration. Full article

Star polymers—macromolecules featuring multiple arms radiating from a central core—offer unique potential for biomedical applications due to their tunable architecture, multifunctionality and ability to incorporate stimuli-responsive and biocompatible components. In this study, functional star polymers with oligo (ethylene glycol) methyl ether methacrylate (OEOMA) arms and 2-(dimethylamino)ethyl methacrylate (DMAEMA) core units were synthesized via atom transfer radical polymerization (ATRP) using the “arm-first” strategy. The star polymers were used as nanoreactors for the in situ reduction of silver nitrate to form silver nanoparticles (AgNPs) without additional reducing agents. UV–Vis spectroscopy confirmed the formation of spherical AgNPs with absorption maxima around 430 nm, and transmission electron microscopy revealed uniform particle morphology. These hybrid nanomaterials (STR-AgNPs) were incorporated into polymethyl methacrylate (PMMA)-based bone cement to impart antibacterial properties. Mechanical testing showed that the compressive strength remained within acceptable limits, while antibacterial assays against E. coli demonstrated a significant inhibition of bacterial growth. These findings suggest that STR-AgNPs serve as promising candidates for infection-resistant bone implants, providing localized antibacterial effects while maintaining mechanical integrity and biocompatibility. Full article

Objective: Trauma is a leading cause of enophthalmos, typically resulting from an increase in the volume of the bony orbit. The general consensus is that post-traumatic primary deformity repair should aim to restore the premorbid volume, shape, and cosmesis of the orbitozygomatic complex (OZC). This study aims to utilise novel three-dimensional (3D) printed patient-specific moulds to intraoperatively fabricate enophthalmos wedges and onlays using polymethylmethacrylate (PMMA) bone cement to reconstruct the OZC. Methods: A total of seven patients underwent digital surgical planning using Freeform software to virtually correct orbitozygomatic complex deformities guided by a design algorithm. Three-dimensionally printed nylon patient-specific moulds were used intraoperatively to fabricate enophthalmos wedges and/or onlays using an industry-standard PMMA bone cement. Clinical examination and application of the proposed design algorithm determined that enophthalmos wedges were indicated for four patients, with one also requiring an onlay; and periorbital onlays were required for the three remaining patients. Results: Hertel exophthalmometry at a mean follow-up of 19.1 months demonstrated good outcomes in the correction of post-traumatic enophthalmos and hypoglobus and with patients reporting good subjective cosmetic results. Patients 5 and 7 had follow-up three-dimensional computed tomography (3D-CT) to confirm correct placement. Conclusion: The use of patient-specific PMMA wedges and onlays, fabricated intraoperatively with the aid of 3D-printed moulds, offers a reliable and effective approach for correcting post-traumatic enophthalmos and hypoglobus. This method allows for the restoration of orbital volume and anatomical contours, addressing both functional and aesthetic concerns. Our results demonstrate that this technique yields favourable outcomes. Full article

Poly (methyl methacrylate) (PMMA) bone cement is widely used in percutaneous vertebroplasty to stabilize osteoporotic vertebral compression fractures. However, its clinical application is limited by its high compressive modulus, risk of thermal necrosis, and poor bone integration, unlike conventional PMMA formulations used in vertebrae or joint arthroplasty, which can reach polymerization temperatures exceeding 100 °C. Spine-specific PMMA is formulated to cure at a reduced polymerization temperature, thereby minimizing the rise in core temperature during the setting process. Consistent with our hypothesis, this moderate thermal output induces localized thermal injury that triggers osteogenic responses and extracellular matrix production, thereby enhancing osteoblast activity in the surrounding bone. This study aimed to evaluate bone remodeling following spine-specific PMMA injection in an osteoporotic Sprague-Dawley (SD) rat model. Twenty-four osteoporotic female SD rats were randomly assigned to three groups: Control (untreated), OVX + spine-specific PMMA (OVX + PMMA), and OVX (OVX + Defect). Bone regeneration was assessed using dual-energy X-ray absorptiometry (DXA), micro-computed tomography (Micro-CT), quantitative PCR (qPCR), immunohistochemistry (IHC), and Western blotting. At 12 weeks post-injection, the OVX + PMMA group exhibited significantly greater bone regeneration than the OVX group. Micro-CT analysis demonstrated a marked increase in trabecular thickness in the PMMA-treated group. Notably, bone formation was more pronounced in regions surrounding the cement compared to adjacent untreated areas. This suggests that spine-specific PMMA promotes osteogenesis via localized thermal necrosis and subsequent osteoblast recruitment. These findings highlight the dual role of spine-specific PMMA in both structural stabilization and biologically driven bone regeneration. Further research is warranted to optimize its clinical applications while minimizing potential adverse effects. Full article

Temporomandibular joint (TMJ) ankylosis compromises essential functions such as chewing, phonation, and breathing. Surgical treatment aims to restore mandibular mobility and prevent the recurrence of joint fusion. This article describes a technical variation based on Puricelli biconvex arthroplasty, using surgical cement, screw fixation, and 3D-printed cutting guides based on virtual planning, allowing for greater precision in joint reconstruction. In this work, we present the step-by-step process used in the customization of cutting guides, virtual planning, and the production of the interposition material with PMMA associated with fixation with titanium screws as a hybrid method for the treatment of recurrent TMJ ankylosis. This reported technique is demonstrated to be reproducible, low-cost, and effective. Full article

Experimental wear simulation of a PEEK-OPTIMA™ polymer-on-UHMWPE total knee replacement has shown equivalent UHMWPE wear to conventional knee replacement materials (cobalt chrome-on-UHMWPE) when tested in a clean environment. The aim of this study was to experimentally investigate the wear of this all-polymer total knee replacement under third body wear conditions. Three PEEK-OPTIMA™ and three cobalt chrome femoral components articulating against all-polyethylene tibial components were tested in a knee simulator. One million cycles of wear simulation was carried out in clean lubricant under conditions replicating walking followed by one million cycles with the lubricant contaminated with porcine bone particles, then one million cycles with PMMA cement particles. UHMWPE wear was determined gravimetrically. Statistical analysis compared UHMWPE wear against PEEK femoral components to cobalt chrome. In clean lubricant and with bone particles in the lubricant, there was no significant difference (p > 0.05) in UHMWPE wear against the different femoral component materials, and wear rates were similar under both conditions. With PMMA particles, there was a dramatic increase in UHMWPE wear for both knee replacement systems but no significant difference (p > 0.05) in UHMWPE wear between the femoral component materials. This is the first study to investigate wear of an all-polymer knee under third body wear conditions. Full article

Background and Objectives: The use of stereolithographic (SLA) 3D printing technology in dentistry has expanded, particularly for the fabrication of provisional dental restorations. Understanding the mechanical properties and quality of SLA 3D-printed materials is essential to ensure clinical success and patient safety. This systematic review aims to critically evaluate and summarize the available evidence on the mechanical properties and quality of SLA 3D-printed materials. Methods: A comprehensive literature search was conducted in PubMed, Scopus, Embase, Cochrane, and Web of Science up to October 2024. Studies comparing the mechanical properties of SLA 3D-printed provisional restoration materials with those of milled, conventional, or other additive manufacturing methods were included. Nine studies met the inclusion criteria. Data on flexural strength, hardness, fracture resistance, surface roughness, marginal adaptation, accuracy, cement film thickness, shear bond strength, and biofilm formation were extracted and analyzed. Results: The findings from the included studies indicate that SLA 3D-printed materials exhibit varied mechanical properties. Some studies reported that SLA 3D-printed resins had significantly lower flexural strength and hardness compared to milled PMMA and bis-acrylic resins. Other studies found that SLA 3D-printed resins showed clinically acceptable marginal adaptation, surface roughness, and fracture strength comparable to those fabricated by subtractive manufacturing and conventional methods. In terms of accuracy, build orientation influenced the dimensional accuracy of SLA-printed restorations. Studies assessing cement film thickness found that SLA-printed provisional restorations had higher cement film thickness compared to other materials. Regarding repairability and fatigue resistance, limitations were observed in some SLA resins. Conclusions: The mechanical properties and quality of SLA 3D-printed materials for provisional dental restorations vary among studies. While SLA technology holds promise for efficient fabrication of provisional restorations, inconsistencies in material properties suggest a need for further research to optimize materials and printing parameters. Standardization of protocols is necessary to ensure reliable clinical performance of SLA 3D-printed provisional restorations. Full article

Polymethyl methacrylate (PMMA) bone cement has been a transformative material in orthopedics since its introduction in the mid-20th century. Originally used in dental medicine, PMMA was adopted for orthopedic applications by Sir John Charnley in the 1950s, significantly enhancing joint replacement surgeries. The primary appeal of PMMA lies in its biocompatibility, mechanical strength, and ease of handling, making it a favored choice for various orthopedic procedures, including arthroplasties and limb-salvage surgeries. However, the exothermic polymerization process of PMMA poses a risk of thermal necrosis in the surrounding bone tissue, as local temperatures can exceed 70 °C, causing damage to osteocytes. Research has sought to mitigate these risks by optimizing mixing techniques, reducing cement mantle thickness, and incorporating cooling methods. Recent advancements, such as the use of phase-change materials (PCMs) and alternative monomers, have shown promise in lowering the exothermic peak during polymerization. Other strategies include pre-cooling the cement and prosthetic components and using composite cement. Despite these innovations, managing the balance between minimizing heat generation and maintaining mechanical properties remains a challenge. The impact of thermal necrosis is significant, compromising implant stability and osseointegration. Understanding the complex interactions between PMMA’s thermal properties and its clinical outcomes is essential for improving orthopedic surgical practices and patient recovery. Full article

Introduction: Despite the rising global awareness and improvement of socioeconomic and living standards, the prevalence of diabetic osteomyelitis (DOM) and its complications has been increasing rapidly. This study aims to investigate the long-term prognosis of DOM of the foot treated using antibiotic-impregnated cement spacer (ACS) and the contributing risk factors for reoperation. Methods and Materials: We retrospectively reviewed the data of 55 diabetic patients with Meggitt-Wagner Grade IIB wounds diagnosed with osteomyelitis of the foot, treated in our institution with excessive debridement, excision of the infected tissue, and implantation of antibiotic-impregnated cement spacer fixed with a Kirschner wire. Descriptive statistics, including patient demographics, were analyzed. Statistical analysis was performed using point-biserial correlation and a Chi-square test with Cramer’s V effect-size estimation to determine the relationship between reoperation and various parameters. Results: 55 patients (36 (65.45%) males and 19 (34.55%) females) with a median age of 64 (39–84) years were thoroughly analyzed throughout a median follow-up of 884 days (2–4671 days). Of the entire cohort, 29 (52.72%) patients achieved primary successful infection eradication without any further intervention, and 8 (14.54%) patients were successfully treated using a secondary procedure. More than half of the reoperated patients underwent the secondary intervention within less than a month after the primary ACS. When assessing correlation, age (r = 0.28, p = 0.04), gender (r = 0.31, p = 0.02), Staphylococcus aureus (r = −0.10, p = 0.04), and the use of gentamicin-only antibiotic cement spacer (r = 0.34, p = 0.01) demonstrated statistically significant correlation to reoperation. 89.18% of the patients who achieved infection eradication did not undergo cement removal. Conclusions: ACS has shown excellent results in eradicating bone infection with up to 7.23 years of follow-up, acting as a structural stabilizer, preventing soft tissue contractures, and delivering highly concentrated local antibiotic treatment both to soft tissue and bone. Regardless, specific factors should be thoroughly evaluated prior to surgery, as advancing age, gender, and the use of gentamicin-only antibiotics appear to be positively associated with a higher likelihood of reoperation. Conversely, infections caused by cultured Staphylococcus aureus seem to be inversely related to reoperation. Full article

Background: The use of antibiotic-loaded bone cements (ALBCs) in arthroplasty has been well established for the prevention and treatment of infections. Tigecycline (Tig), a broad-spectrum antibiotic, has shown efficacy against various pathogens, including vancomycin-resistant strains. Method: ISO and DIN mechanical and microbiological inhibition zone tests were performed on PMMA cement with manually added Tigecycline. Results: Manually adding 0.5 and 1.0 g Tigecycline to PMMA always meets the mechanical requirements of ISO and DIN standards. Mixtures containing 0.5 g were microbiologically effective for up to 7 days and those containing 1.0 g were effective for 28–42 days. Conclusion: In revision surgery, manually adding Tigecycline in doses of 0.5–1 g to 40 g of PMMA is effective against MRSA, VRE, and ESBL without negatively affecting the cement’s properties. Full article

Esthetically pleasing temporary prostheses are often necessary for extended periods in a variety of clinical scenarios. Adjustments to the occlusion or margins are commonly needed before cementing the temporary prosthesis. Therefore, it is clinically necessary to repolish the rough surface to avoid biological and esthetic issues associated with rough surfaces. The purpose of this in vitro study was to assess and compare the impact of various polishing protocols on the surface roughness and color stability of three resin materials used for provisional crowns. A total of 150 specimens were fabricated from auto-polymerizing polymethyl methacrylate, bis-acryl composite, and Methyl methacrylate-LC resin using a stainless steel mold. Each material group was divided into five groups (n = 10) based on the applied surface treatment: positive control group (G1): no roughening or surface treatment, Negative control group (G2): acrylic bur-roughened surface without any polishing, the different surface treatment groups of silicon carbide and aluminum oxide stone polishing (G3), diamond-coated rubber twist (G4), and Surface Glaze (G5). An optical profilometer was used to assess the surface roughness of all samples. After undergoing 6000 cycles of thermocycling followed by immersion in a coffee solution for 15 days at 37 °C, color parameters were measured using a spectrophotometer both before and after a storage period to evaluate color differences. A two-way ANOVA test with α = 0.05 significance level was carried out to determine the impacts of both the materials utilized and the polishing protocol. Among the three types of resin examined, the bisacryl group exhibited superior surface quality in positive control groups, while PMMA resin demonstrated higher polishability. The diamond-coated rubber twits resulted in lower Ra values of 0.36 (0.01) µm, 0.52 (0.11) µm, and 0.28 (0.05) µm for PMMA, BAMA, and MMLC resins, respectively. The application of photo-polymerized surface glaze led to a plaque accumulation threshold of 0.2 µm across all resin groups. The greatest mean color change occurred in the negative control group, indicating a propensity for more staining on rougher surfaces. The Bisacryl resin exhibited higher ΔE values, whereas PMMA showed better color stability. The lowest ΔE values were found when the surface glaze was applied to all of the provisional crown resins. Untreated Bisacryl resin exhibited the lowest Ra values, while PMMA resins demonstrated superior surface morphology after polishing. PMMA provisional crown resins showed increased resistance to staining. The use of surface glaze enhanced both smoothness and color stability on the surfaces. Full article

(1) Background: There is an ongoing discussion on the elution efficacy of antibiotic-impregnated cements. Our experiments were intended to clarify if there are differences in the antibiotic elution of HPLC compared with inhibition zone testing using eluates or PMMA discs. (2) Materials and Methods: Two cement brands with different concentrations of the active ingredient were tested in antimicrobial Kirby–Bauer (disc diffusion) assays. Cement platelets were directly applied on the agar plates and their zone of inhibition was measured. In parallel, the platelets were incubated in phosphate buffered saline (PBS) and at distinct points of time transferred into new buffer. At these time points, 50 µL of the bone cement eluates was used for zone of inhibition testing. Standard gentamicin sulfate solutions served as a control in the same test setup. To verify the microbiological investigations, the antibiotic content of the eluates was also measured via high-performance liquid chromatography (HPLC). (3) Results: The experiments with cement eluates showed better differentiable results than the direct application of the cement discs. The results were also comparable to investigations with HPLC and gentamicin sulfate standard solutions. (4) Conclusions: The results of elution rates are influenced by the test system and the period of observation chosen. The microbial test systems reflect the results of HPLC to the same degree and give evidence of the efficacy of the antibiotics. The HPLC tests on eluates were more suitable in representing differences in release characteristics. Full article

(1) Background: The addition of antibiotics to bone cements is a common practice in the treatment of periprosthetic joint infections. In revision cases, the amount and type of antibiotic is often insufficient and additional antibiotics must be added. The addition, however, changes the product itself, and the surgeon becomes the “manufacturer” of the bone cement. PMMAe wished to clarify whether the admixture of antibiotics changes the mechanical stability of the bone cements used and if the added antibiotics were still functional and released in sufficient quantities. (2) Methods: We compared two industrially manufactured vancomycin-containing PMMA cements; the low-viscous VancogenX^® (TECRES, Sommacampagna, Italy) and the high-viscous Copal^® G+V (Heraeus Medical GmbH, Wehrheim, Germany), with two PMMA cements loaded with aminoglycosides, to which 2.0 g of vancomycin (Hexal CT1631) were manually added—the high-viscous Smartset^® GHV and the medium-viscous Antibiotic Simplex with Tobramycin (antibiotic Simplex^® T). Test specimens of the bone cements were used to determine mechanical stability (bending strength and bending module), and the release of the antibiotics was determined by HLPC and modified Kirby–Bauer assays. (3) Results: All tested bone cements showed an initial high release within the first hours. Repeated testing after 24 h showed a reduced efficacy of VancogenX^® and Smartset^® GHV in Kirby–Bauer assays. Long-time release over days showed a release of functional antimicrobial active ingredients over this period of time in anti-microbial assays, but no activity of VancogenX^® from day 21 onward. No significant differences in the ISO bending modules could be detected, but in contrast to the bending module, the ISO bending strength was substantially reduced by 10–15 mPal in comparison to both cements of the reference group. The Simplex^®T met just the ISO 5833; the Smartset^® GHV did not after adding vancomycin. (4) Conclusions: In conclusion, the manual addition of 2 g of vancomycin to 40 g of PMMA powder is recommended for the treatment of methicillin-resistant staphylococci. Vancomycin is released over a period of 42 days with concentrations above the MIC for typical staphylococci. The mechanical properties of the PMMA just met, or did not fulfill, ISO mechanical specification. Copal^® G+V showed a better elution than VancogenX^® over time. Full article