Retention Device Research Articles

Letter to Editor: “Cracked vials due to variable faricimab (Vabysmo®) vial sizes used with a vial retention device: A Case Report”

Letter to Editor: “Cracked vials due to variable faricimab (Vabysmo®) vial sizes used with a vial retention device: A Case Report”

Response to: Letter to Editor: “Cracked vials due to variable faricimab (Vabysmo®) vial sizes used with a vial retention device: A Case Report”

Response to: Letter to Editor: “Cracked vials due to variable faricimab (Vabysmo®) vial sizes used with a vial retention device: A Case Report”

Survey - Based Study For Common Retention Practices Among Orthodontists In North Macedonia

Background: Orthodontic therapy always ends with retention to prevent the return of the final occlusal outcome and to maintain the teeth in the correct position after the end of orthodontic therapy. This research aimed to survey retention practices, factors affecting retention protocol and differences regarding retention among orthodontists in North Macedonia. Material and methods: 150 questionnaire copies were distributed by mail or personally to orthodontics in North Macedonia. The survey included 24 single or multiple-answer questions, about retention system, frequently used fixed and removable retainers in certain malocclusions, the duration of the retention period, retainer supervision, instructions for patients, and the need for retention guidelines in order to determine habits and knowledge, and reasons for choosing a particular retention regime. Results : Out of 150 questionnaires, 93 were appropriately filled out and returned, so response rate was 62%. 90% give oral information about retention, only 25% informed their patients both oral and written. The most preferred retainer in maxilla (54%) was vacuum-formed appliance, than removable acrylic plate appliance (41%) and only 9% bonded retainer. In mandible, mostly used are VFR (45%), then acrylic plate appliance (29%), bonded retainers (20%). Dual retention was used more in upper jaw. The retention period was 4 to 5 years or lifelong; the choice of retention device in 77% depended on malocclusion. The reason for the choice of VFR are availability (50,5%), quality (36,56%), low-cost (33,3%). Protocol was influenced by clinical experience (75%), knowledge from residency (58%), courses (56%) and from colleagues (40%). 83% made changes in retention protocol in past years, in appliance time (20%) or in retention period (19%). 95,7% of the surveyed orthodontists believe that general guidelines for retention are needed. Conclusions: The most preferred retainers in North Macedonia were vacuum-formed appliance, than removable acrylic plate appliance and at least bonded retainer. Combination of fixed and removable appliance in mandible were used less than in upper jaw. Reason for choosing was malocclusion. Retention protocols are influenced mostly by the clinical experience. Common retention guidelines are required for most orthodontists.

Magnetic Attachment For Tooth Supported Mandibular Overdenture: A Case Report

The goal of preventive prosthodontics is to highlight the significance of any surgery that can postpone or completely prevent future prosthodontic issues. In terms of preventive prosthodontics, the overdenture is a therapeutic option that is supported by science. Overdentures have been fitted with a variety of attachments to improve retention. Because rare earth magnets like Sm-Co and Nd-Fe-B may be produced in small sizes as retentive devices for complete dentures, detachable partial dentures, obturators, and maxillofacial prosthesis, their application for increasing retention has been widely used in the field of prosthodontics. This article presents a simple method of fabricating mandibular over denture retained by magnets in a patient whose mandibular residual ridge was severely resorbed with few remaining teeth and opposed by maxillary complete denture

Posture Retention Devices for Older Adults Undergoing Horseback Riding Therapy

Posture Retention Devices for Older Adults Undergoing Horseback Riding Therapy

Evaluation of various membranes at different fluxes to enable large-volume single-use perfusion bioreactors.

The growing demand for biological therapeutics has increased interest in large-volume perfusion bioreactors, but the operation and scalability of perfusion membranes remain a challenge. This study evaluates perfusion cell culture performance and monoclonal antibody (mAb) productivity at various membrane fluxes (1.5-5 LMH), utilizing polyvinylidene difluoride (PVDF), polyethersulfone (PES), or polysulfone (PS) membranes in tangential flow filtration mode. At low flux, culture with PVDF membrane maintained higher cell culture growth, permeate titer (1.06-1.34 g/L) and sieving coefficients (≥83%) but showed lower permeate volumetric throughput and higher transmembrane pressure (TMP) (>1.50 psi) in the later part of the run compared to cultures with PES and PS membrane. However, as permeate flux increased, the total mass of product decreased by around 30% for cultures with PVDF membrane, while it remained consistent with PES and PS membrane, and at the highest flux studied, PES membrane generated 12% more product than PVDF membrane. This highlights that membrane selection for large-volume perfusion bioreactors depends on the productivity and permeate flux required. Since operating large-volume perfusion bioreactors at low flux would require several cell retention devices and a complex setup, PVDF membranes are suitable for low-volume operations at low fluxes whereas PES membranes can be a desirable alternative for large-volume higher demand products at higher fluxes.

A modular and multi-functional purification strategy that enables a common framework for manufacturing scale integrated and continuous biomanufacturing.

Biopharmaceutical manufacture is transitioning from batch to integrated and continuous biomanufacturing (ICB). The common framework for most ICB, potentially enables a global biomanufacturing ecosystem utilizing modular and multi-function manufacturing equipment. Integrating unit operation hardware and software from multiple suppliers, complex supply chains enabled by multiple customized single-use flow paths, and large volume buffer production/storage make this ICB vision difficult to achieve with commercially available manufacturing equipment. Thus, we developed SymphonX™, a downstream processing skid with advanced buffer management capabilities, a single disposable generic flow path design that provides plug-and-play flexibility across all downstream unit operations and a single interface to reduce operational risk. Designed for multi-product and multi-process cGMP facilities, SymphonX™ can perform stand-alone batch processing or ICB. This study utilized an Apollo™ X CHO-DG44 mAb-expressing cell line in a steady-state perfusion bioreactor, harvesting product continuously with a cell retention device and connected SymphonX™ purification skids. The downstream process used the same chemistry (resins, buffer composition, membrane composition) as our historical batch processing platform, with SymphonX™ in-line conditioning and buffer concentrates. We used surge vessels between unit operations, single-column chromatography (protein A, cation and anion exchange) and two-tank batch virus inactivation. After the first polishing step (cation exchange), we continuously pooled product for 6 days. These 6 day pools were processed in batch-mode from anion exchange to bulk drug substance. This manufacturing scale proof-of-concept ICB produced 0.54 kg/day of drug substance with consistent product quality attributes and demonstrated successful bioburden control for unit-operations undergoing continuous operation.

Optimization of the condition of organs and tissue of the oral during the retention period of orthodontic treatment

Relevance. The retention period is the most important stage during which the structural and functional state of the organs and tissues of the mouth must be fully restored after long-term orthodontic treatment. An increase in the time spent by orthodontic equipment in the oral cavity associated with the use of retention devices also increases the risk of developing complications from the hard tissues of teeth and periodontal tissue, while the problem of preventing these complications is not fully addressed.Purpose. Based on a multi-level study of the condition of the organs and tissues of the mouth, to evaluate the effectiveness of the use of modern domestic means of intraoral hygiene in the retention period of orthodontic treatment.Materials and methods. 84 patients aged 18 to 45 years during the retention period of orthodontic treatment were examined. The control group consisted of 32 people using usual hygiene products. Patients of the second group (28 people) were prescribed anti-inflammatory hygiene products for the first 7 days after removal of the equipment; then using a combination of anti-inflammatory and remineralizing intraoral agents based on hydroxyapatite. In the third group (24 people), a rinse aid based on benzydamine (0.15%) and chlorhexidine (0.05%) was prescribed for the first 7 days after removal of the equipment; then use your usual hygiene products and any means to remineralize the enamel at night. The condition of periodontal tissues was assessed using the PMA index and the CPITN index. Enamel caries resistance was determined using the TER test. The desensitivity effect was studied using the dental sensitivity index of L.Yu. Orekhova - S.B. Ulitovsky. Examinations of patients were carried out on the day of removal of fixed orthodontic equipment, after 7 days, after a month and after 3 months from the start of the study.Results. The dynamics of changes in the CPITN index in the second group were 9.1% after 7 days of use, 35.6% after a month of study and 46.2% after 3 months from the start of observation. The dynamics of changes in the PMA index were 13.6% after 7 days of use, 39.7% after a month of study and 47.7% after 3 months from the start of observation. Remineralizing efficiency in the second group improved by 13.1% after 7 days, after a month of use to 36.1%, and after 3 months it increased to 57.4%. In patients of the second group, the desensitizing effectiveness was 27%, after 1 month -47%, after three months -56%.Conclusions. The data obtained allow us to recommend proven oral care products during the retention period of orthodontic treatment for the purpose of primary and secondary prevention of diseases of the hard tissues of teeth and periodontal tissue after removal of fixed orthodontic equipment (brackets).

Characterization of cellular responses and cell lysis to elevated hydrodynamic stress from benchtop perfusion bioreactors.

The effective design of perfusion cell culture is currently challenging regarding balancing the operating parameters associated with the hydrodynamic conditions due to increased system complexity. To address this issue, cellular responses of an industrial CHO cell line to different types of hydrodynamic stress in benchtop perfusion bioreactors originating from agitation, sparging, and hollow fibers (HF) in the cell retention devices were systematically investigated here with the analysis of cell lysis. It was found that cell lysis was very common and most associated with the sparging stress, followed by the HF and lastly the agitation, consequently heavily impacting the estimation of process descriptors related to biomass. The results indicated that the agitation stress led to a reduced cell growth with a shift toward a more productive phenotype, suggesting an energy redirection from biomass formation to product synthesis, whereas the sparging stress had a small impact on the intracellular metabolic flux distribution but increased the cell death rate drastically. For HF stress, a similar cell maintenance profile was found as the sparging while the activity of glycolysis and the TCA cycle was significantly impeded, potentially leading to the lack of energy and thus a substantial decrease in cell-specific productivity. Moreover, a novel concept of volume average shear stress was developed to further understand the relations of different types of stress and the observed responses for an improved insight for the perfusion cell culture.

Effect of inner diameter, filter length, and pore size on hollow fiber filter fouling during perfusion cell culture.

As the need for higher volumetric productivity in biomanufacturing grows, biopharmaceutical companies are increasingly investing in a perfusion cell culture process, most commonly one that uses a hollow fiber filter as the cell retention device. A current challenge with using hollow fiber filters is fouling of the membrane, which reduces product sieving and can increase transmembrane pressure (TMP) past process limitations. In this work, the impact of hollow fiber filter geometries on product sieving and hydraulic membrane resistance profiles is evaluated in a tangential flow filtration (TFF) perfusion system. The hollow fibers tested had lengths ranging from 19.8 to 41.5 cm, inner diameters (IDs) ranging from 1.0 to 2.6 mm, and pore sizes of 0.2 or 0.65 μm. The results showed that the shortest hollow fibers experienced higher product sieving while larger IDs contributed to both higher product sieving and lower hydraulic membrane resistances, illustrating the impact of filter geometry on process performance. The results also showed 0.2 μm pore size filters maintain higher product sieving, but also higher membrane resistances compared to 0.65 μm pore size filters. This study highlights the need for optimized hollow fiber filter geometries to maximize use of the membrane area, which in turn can reduce production costs and increase scalability of the perfusion process.

Aesthetics in Removable Partial Dentures: Modification of the Proximal Plate and Retentive Lamellae in Kennedy Class II Scenarios

The removable partial denture, despite new technologies and new materials, continues to play a significant role in clinical dental practice. The purpose of the following study was to evaluate the design of new retention devices in Kennedy class II scenarios. For the study of “lamellar” retentive devices, four prosthetists were chosen. According to inclusion and exclusion criteria, prosthetists selected 16 patients (8 women and 8 men) whose upper arches had to be rehabilitated using a removable partial prosthesis. The results showed that the parameters taken into consideration, such as satisfaction, stability, aesthetics, and retention, had an average score that was higher than 3.30 (range 1–4), with an average standard deviation of 0.6225 in the four parameters, indicative that the data were relatively homogeneous and coherent. In conclusion, we can state that the skeletonized prosthesis with lamellar retentions, designed for Kennedy class II scenarios, has shown high acceptance in selected patients.

Effects of Material Composition of Heat Retention Devices on Thermal Characteristics

Effects of Material Composition of Heat Retention Devices on Thermal Characteristics

Intestinal retentive systems - recent advances and emerging approaches.

Intestinal retentive devices (IRDs) are devices designed to anchor within the lumen of the intestines for long-term residence in the gastrointestinal tract. IRDs can enable impactful medical device technologies including sustained oral drug delivery systems, indwelling sensors, or real-time diagnostics. The design and testing of IRDs present a myriad of challenges, including precise deployment of the device at desired intestinal locations, secure anchoring within the gastrointestinal tract to allow for natural function, and safe removal of the IRD at user-defined times. Advancing the state-of-the-art of IRD is an interdisciplinary effort that requires innovations such as new materials, novel anchoring mechanisms, and medical device design with consistent input from clinical practitioners and end-users. This perspective briefly reviews the current state-of-the-art for IRDs and charts a path forward to inform the design of future concepts. Specifically, this article will highlight materials, retention mechanisms, and test beds to measure the efficacy of IRDs and their mechanisms. Finally, potential synergies between IRD and other medical device technologies are presented to identify future opportunities.

Influence of attaching mechanical retentive devices onto frameworks on fracture resistance of implant-supported zirconia crowns.

This study investigated the fracture load of implant-supported zirconia crowns (IZCs), in which indirect composite resin or feldspathic porcelain was layered onto zirconia frameworks with mechanical retentive devices. Three different zirconia frameworks were assessed: attaching mechanical retentive devices on glaze and opaque porcelain materials (GL and OP groups, respectively), and no attaching mechanical retentive devices (ND group). The frameworks were layered using feldspathic porcelain (FP veneer) and indirect composite resin (IC veneer). Fracture load of the specimens was measured. In FP veneer, the GL group recorded the highest fracture load. In the IC veneer, the GL and OP groups had significantly higher fracture load than the ND group. The fracture resistance of IZCs can be enhanced by applying glaze material before attaching mechanical retentive devices for porcelain layering. The mechanical retentive devices effectively yielded mechanical interlocking between the zirconia frameworks and the IC veneer in GL and OP groups.

Methods of treatment of patients with skeletal forms of distal occlusion using dental alveolar compensation. The role of digital technologies and the approach to treatment

Improving the effectiveness of complex treatment in patients with distal occlusion of the dentition during the period of active skeletal growth. 202 patients with skeletal distal occlusion were examined and treated. Patients are divided into three subgroups depending on the position/size of the jaw bones and the main link of pathogenesis. The parameters of TRG and CBCT sections were measured before and after treatment. Various parameters were used for the analysis: skeletal (SNA, SNB, ANB, etc.), dental (II/SN, II/ii, APog-I, APog-i, etc.), skeletal profile and soft tissue parameters. Various orthodontic techniques have been applied, including FNTA, the Damon bracket system, the Biederman apparatus and others. In the retention period, non-removable retainers in the frontal section and removable night retention devices of various structures were used. Patients were monitored for up to 15 years after the completion of the active orthodontic treatment stage. The analysis of the X-ray examination data indicates the normalization of the mutual position of the jaw bones in relation to the base of the skull, optimization of the ratios of the bone elements of the TMJ. An algorithm has been developed for the treatment of patients with dental anomalies in the sagittal plane, with narrowing of the upper jaw during the bite of permanent teeth. Comprehensive treatment of patients with distal occlusion during the period of active skeletal growth makes it possible to achieve significant improvements in dentition, position and closure of teeth, as well as skeletal parameters of X-ray examinations. The results indicate the importance of early intervention using modern orthodontic techniques. Long-term follow-up in the retention period shows the stability of the results and the effectiveness of the treatment.

The use of fixed expanders with orthodontic miniscrews support in children with mesial occlusion

Prevention of the development of pronounced skeletal abnormalities in patients with mesial occlusion. Biometric analysis of control and diagnostic models of dentition was performed in 60 patients with dental anomalies before and after treatment in 3 mutually perpendicular planes to identify violations in the formation of dental arches by sagittal and transversal dimensions, and alveolar processes - by vertical dimensions (methods of A. Pont, G. Korkhaus). Measurements of 23 parameters of TRG and sections of CBCT were carried out using the modified Nad-Ars technique with analysis of skeletal parameters before and after treatment. Treatment was carried out using dilators for the upper jaw in combination with a facial mask and further dynamic observation using active retention devices. The results of treatment showed an increase in the length of the anterior segment of the upper dental arch by 2.8±0.55 mm (p<0.05 mm); expansion in the area of temporary molars by 2.85±0.65 mm (p<0.05); in the area of permanent molars by 2.75±0.55 mm (p<0.05); in the area of the apical basis of HF by 3.82±0.45 mm (p<0.05). The length of the lower dental arch in the anterior segment has not changed. Analysis of TRG parameters showed a significant increase in the values of <ANB - by 1.55±0.52° (p<0.05); Wits - number by 2.85±0.45 mm (p<0.05); total anterior morphological height of the facial skeleton by 4.25±1.53 mm (p<0.05). As a result of the orthodontic treatment, the optimal position of the teeth, the shape of the dental alveolar arches, the inclination of the occlusal plane, and the improvement of the bite were achieved. Early orthodontic treatment made it possible to create favorable conditions and prepare the patient's occlusion for a change of teeth, to form dental alveolar arches, to reduce the degree of complexity of therapeutic measures that may be needed after the completion of skeletal growth.

Intensified Influenza Virus Production in Suspension HEK293SF Cell Cultures Operated in Fed-Batch or Perfusion with Continuous Harvest.

Major efforts in the intensification of cell culture-based viral vaccine manufacturing focus on the development of high-cell-density (HCD) processes, often operated in perfusion. While perfusion operations allow for higher viable cell densities and volumetric productivities, the high perfusion rates (PR) normally adopted-typically between 2 and 4 vessel volumes per day (VVD)-dramatically increase media consumption, resulting in a higher burden on the cell retention device and raising challenges for the handling and disposal of high volumes of media. In this study, we explore high inoculum fed-batch (HIFB) and low-PR perfusion operations to intensify a cell culture-based process for influenza virus production while minimizing media consumption. To reduce product retention time in the bioreactor, produced viral particles were continuously harvested using a tangential flow depth filtration (TFDF) system as a cell retention device and harvest unit. The feeding strategies developed-a hybrid fed-batch with continuous harvest and a low-PR perfusion-allowed for infections in the range of 8-10 × 106 cells/mL while maintaining cell-specific productivity comparable to the batch control, resulting in a global increase in the process productivity. Overall, our work demonstrates that feeding strategies that minimize media consumption are suitable for large-scale influenza vaccine production.

Integrated Semi-Continuous Manufacturing of Lentiviral Vectors Using a HEK-293 Producer Cell Line

There have been considerable efforts on improving the lentiviral vector (LV) system and their production. However, there remains the persisting challenge of producing a sufficient quantity of LVs at manufacturing scale to support treatments beyond early clinical trials. Furthermore, their innately labile nature poses an equally important obstacle in LV production. As LVs lose function over time and they are sensitive to environmental factors in each unit operation in the bioprocess workflow, integrated continuous manufacturing is an attractive strategy for process intensification. This manuscript describes the implementation of nuclease treatment, clarification, and capture step in a semi-continuous mode. Combining the clarification and loading of the capture step as well as operating those steps in parallel to the purification of the capture step expedite the processing time, reducing it by 4-fold as compared to processing the same volume in batch mode using the same membrane size. This semi-continuous operation also improves the recoveries of functional vector particles and total vector particles by 26% and 18%, respectively, showing an added benefit in loading the capture membranes in series in continuous flow chromatography. Building on previously published upstream work using a scalable cell retention device in perfusion mode, this manuscript demonstrates the integration of upstream and downstream in a semi-continuous manner, reducing processing and hold times as well as showing improvements in LV product quality and recovery.

Retention loss and wear assessment of three attachment systems for implant retained-mandibular overdentures: An in vitro study

BackgroundThe stud-shaped attachment systems (AS) with different shape designs (ball, cylindrical, conical) and materials (metallic, plastic, or a combination of both) are commonly used to provide better retention and stability in implant-retained mandibular overdentures (IRMO). PurposeThe purpose of the present study was to evaluate and compare the retention loss and the wear (patterns, location, material loss) of three resilient unsplinted AS: a well-established ball attachment system (BAS) and two more recent cylindrical attachment systems (CAS), Locator R-Tx® and Novaloc®. Materials and methodsThe implants, their corresponding abutments, the color-coded or position-coded retention devices (RD), the matrix metal housing were incorporated within CAD/CAM resin blocks and cyclically loaded with 19.6 N along the implant axis in a chewing machine to simulate 10,000 insertion-removal cycles (IRC). At cycle 10, 100, 1,000, 5,000, and 10,000, the retention force was measured using a universal testing machine. The wear was qualitatively examined using a binocular magnifier for both systems, and quantitatively assessed from micro-computed tomography acquisitions for CAS. Material loss exceeding 50 μm was considered significant. ResultsThe three AS showed different retentive behavior along time. All the Locator R-Tx® RD lost more than 50 % of their retention after 10,000 IRC. The retention of the Ball System slightly varied over time, the final retention loss in Bmed and Bmax groups being lower than 25 % of the initial retention. Wear was located at the tip of their gold RD and at the equator area of their ball abutment. For Locator R-Tx®, the more retentive the plastic RD, the greater its wear and retention loss. Only Novaloc® maintained a stable retention with even a slight tendency to increase and showed a negligible wear. Implant abutments of the CAS showed no significant wear. ConclusionAfter 10,000 IRC, corresponding to approximately 5-years clinical use, almost all RD provided retention force over 5 N, which could be sufficient to maintain satisfaction in most of the patients. The retention loss observed most prominently for the Locator R-Tx®, then for the Ball System, seemed to correlate with the wear observed on their RD. The practitioner may expect less RD maintenance with the Novaloc® stable retention overtime.

Appliances Therapy in Obstructive Sleep Apnoea: A Systematic Review and Meta-Analysis.

Obstructive sleep apnea (OSA) is a recurrent partial or complete obstruction of the upper airway during sleep caused by narrowing or collapse of the pharyngeal wall. It leads to microstimulation and oxyhemoglobin desaturation, resulting in sleepiness and loud snoring. OSA negatively affects the cardiovascular system and may contribute to neurocognitive impairment. The aim of this systematic review is to evaluate the effectiveness and efficacy of appliance therapy in obstructive sleep apnea. The effectiveness was assessed by using the Apnea Hypopnea Index (AHI). An electronic search of the Cochrane Library, PubMed, and Google Scholar was conducted between 1998 and 2021. Articles were independently assessed by three reviewers. The quality of a randomised control trial (RCT) is assessed using the Cochrane risk of bias method. The tool GRADE was used to achieve the desired level of confidence for each outcome reported.Several studies used continuous positive airway pressure (CPAP), mandibular advancement devices (MAD), and tongue retention devices (TRD). The meta-analysis included a total of six papers that met the inclusion criteria. Results showed that CPAP significantly improved AHI compared with an oral appliance (random effects: difference in means = 8.40, 95% CI = 7.21 to 9.60). It was also found that oral appliance (OA) therapy significantly improved AHI compared with baseline before appliance therapy (random effects: mean difference = 13.40, 95% CI = 10.87 to 15.93; p.00001). For mild to moderate OSA, CPAP is considered the gold standard. Our meta-analysis of six RCTs found favorable evidence for OSA patients receiving oral devices; however, they were less effective than CPAP. A subgroup analysis found that MAD may be a beneficial treatment for mild to moderate OSA patients who do not respond to CPAP. The findings suggest that oral appliances may be an effective treatment for OSA, especially in patients with mild to moderate OSA.