Cast-Based Guided Implant Placement and Prosthetic Rehabilitation of a Single Edentulous Space: Case Report and Systematic Analysis of Surgical Guides Used in Implant Dentistry.

This report discusses a clinical case of prosthetic rehabilitation of a single edentulous space using cast-based guided implant placement, a surgical protocol for correct implant installation. It also provides a rundown of various techniques used and surgical guides available in dental implantology. Correct and preplanned implant positioning and angulation are the adjuncts to a successful implant-supported restoration. Initially, the residual bone available and its quality were the sole factors that determined implant position and angulation. Lately, prosthetically driven implant prostheses have ensured good aesthetics, function, and hygiene maintenance resulting in long-term success. A surgical guide provides adequate information regarding implant placement and also provides an aid for implant placement at the time of surgical procedure depending on the type of guide fabricated. Cast-based surgical guide fabrication is precise, economical, and time saving in achieving accurate positioning of the implant and subsequently prosthesis placement for correct functioning.

Ultrasensitive and Robust Point-of-Care Immunoassay for the Detection of Plasmodium falciparum Malaria.

Plasmodium falciparum malaria is widespread in the tropical and subtropical regions of the world. There is ongoing effort to eliminate malaria from endemic regions, and sensitive point-of-care (POC) diagnostic tests are required to support this effort. However, current POC tests are not sufficiently sensitive to detect P. falciparum in asymptomatic individuals. After extensive optimization, we have developed a highly sensitive and robust POC test for the detection of P. falciparum infection. The test is based on upconverting nanophosphor-based lateral flow (UCNP-LF) immunoassay. The developed UCNP-LF test was validated using whole blood reference panels containing samples at different parasite densities covering eight strains of P. falciparum from different geographical areas. The limit of detection was compared to a WHO-prequalified rapid diagnostic test (RDT). The UCNP-LF achieved a detection limit of 0.2-2 parasites/µL, depending on the strain, which is 50- to 250-fold improvement in analytical sensitivity over the conventional RDTs. The developed UCNP-LF is highly stable even at 40 °C for at least 5 months. The extensively optimized UCNP-LF assay is as simple as the conventional malaria RDTs and requires 5 µL of whole blood as sample. Results can be read after 20 min from sample addition, with a simple photoluminescence reader. In the absence of a reader device at the testing site, the strips after running the test can be transported and read at a central location with access to a reader. We have found that the test and control line signals are stable for at least 10 months after running the test. The UCNP-LF has potential for diagnostic testing of both symptomatic and asymptomatic individuals.

Development of a Fast SARS-CoV-2 IgG ELISA, Based on Receptor-Binding Domain, and Its Comparative Evaluation Using Temporally Segregated Samples From RT-PCR Positive Individuals.

SARS-CoV-2 antibody detection assays are crucial for gathering seroepidemiological information and monitoring the sustainability of antibody response against the virus. The SARS-CoV-2 Spike protein's receptor-binding domain (RBD) is a very specific target for anti-SARS-CoV-2 antibodies detection. Moreover, many neutralizing antibodies are mapped to this domain, linking antibody response to RBD with neutralizing potential. Detection of IgG antibodies, rather than IgM or total antibodies, against RBD is likely to play a larger role in understanding antibody-mediated protection and vaccine response. Here we describe a rapid and stable RBD-based IgG ELISA test obtained through extensive optimization of the assay components and conditions. The test showed a specificity of 99.79% (95% CI: 98.82-99.99%) in a panel of pre-pandemic samples (n = 470) from different groups, i.e., pregnancy, fever, HCV, HBV, and autoantibodies positive. Test sensitivity was evaluated using sera from SARS-CoV-2 RT-PCR positive individuals (n = 312) and found to be 53.33% (95% CI: 37.87-68.34%), 80.47% (95% CI: 72.53-86.94%), and 88.24% (95% CI: 82.05-92.88%) in panel 1 (days 0-13), panel 2 (days 14-20) and panel 3 (days 21-27), respectively. Higher sensitivity was achieved in symptomatic individuals and reached 92.14% (95% CI: 86.38-96.01%) for panel 3. Our test, with a shorter runtime, showed higher sensitivity than parallelly tested commercial ELISAs for SARS-CoV-2-IgG, i.e., Euroimmun and Zydus, even when equivocal results in the commercial ELISAs were considered positive. None of the tests, which are using different antigens, could detect anti-SARS-CoV-2 IgGs in 10.5% RT-PCR positive individuals by the fourth week, suggesting the lack of IgG response.

Prosthodontic rehabilitation of patient with flabby ridges with different impression techniques.

A fibrous or flabby ridge is a superficial area of mobile soft tissue affecting the maxillary or mandibular alveolar ridges. It can develop when hyperplastic soft tissue replaces the alveolar bone and is a common finding particularly in the upper anterior region of long term denture wearers. Masticatory forces can displace this mobile denture-bearing tissue, leading to altered denture positioning and loss of peripheral seal. Forces exerted during the act of impression making can result in distortion of the mobile tissue. Unless managed appropriately by special impression techniques, such 'flabby ridges' adversely affect the support, retention and stability of complete dentures. This paper presents three case reports for prosthodontic rehabilitation of patient with flabby ridges with three different impression techniques.

Effect of firing cycle and surface finishing on the sag resistance of long-span metal ceramic framework using base metal alloys-an in vitro study.

BACKGROUND: The search for the ideal restorative material or combination of materials in dentistry is still the subject of modern dental research. In clinical practice, there are increased numbers of ceramo-metal restorations being fabricated which replace multiple missing teeth in a single framework. The literature is scanty with regard to investigations of the 'sag' resistance of base metal alloys commonly used for ceramo-metal restorations and specifically for long-span restorations. An in vitro study was carried out to investigate the effects of surface finishing and simulated porcelain-firing on the sag resistance of long-span ceramo-metal frameworks using base metal alloys. METHOD: Four types of alloys were used. A total of 80 samples were selected for the study and they were divided into four groups of 20 samples each. 'As cast' metal specimens in group I, group II and with surface finishing in group III and group IV. Each test sample was mounted on the sample holding accessory of the custom made thermo mechanical analyser and subjected to three firing cycles. Each sample was evaluated for the sag-related deflection recorded by the dial gauge with an accuracy of 1 µm. The data recorded was subjected to a statistical analysis using unpaired t-test to compare the relative difference in the sag-related deflection values. RESULTS: It was observed that the values for sag-related deflection were significantly less for the 'as cast' samples of all the alloy groups. Nickelchromium (NiCr) and cobaltchromium (CoCr) exhibited value of 19.4 µm and 14.8 µm, respectively. CONCLUSION: Among the four groups of alloys tested, CoCr based alloy exhibited the least amount of sag-related deflection. The results show that the sag-related deflection was less in Co-Cr alloys as compared with the NiCr alloys, still Ni-Cr alloys in fixed dental prostheses frameworks are used due to their desirable physical and chemical properties.

Dimensional Accuracy of Castings Fabricated with Ring-less and Metal Ring Investment Systems for Implant Supported Fixed Dental Prosthesis: An In-vitro Comparative Study.

BACKGROUND: The ring-less investment system is in use for dental casting, although there was no adequate scientific data to support its use either for conventional fixed dental prosthesis or implant retained fixed dental prosthesis. METHODS: An in-vitro study was undertaken to compare the vertical marginal accuracy of single full coverage metal restorations, between ring-less and metal ring investment techniques, using two different investment materials, for implant supported fixed dental prosthesis. Three groups were made of ten samples each. Group I consisted of metal ring with PCT® FlexVest (phosphate bonded investment material). Group II consisted of metal ring with Bellasun® investment material. Group III and the final group consisted of ring-less investment system and Bellasun® investment material. The wax patterns were prepared on a metal die, cast and finished. The cast restorations (samples) were again seated on the metal die and the accuracy of fit was evaluated by measuring the gap between the finish line on the die and the margins of the sample at four specific sites using a profile projector (Helios-350H, Microtecnica, LTF, Italy) having accuracy of 1µm. RESULT: Mean marginal accuracy for Group-III was found to be the least (58.87 +17.87 µm) followed by Group-II (97.23 + 16.37 µm), and Group-I (109 + 7.55 µm). However, Group I showed the least variability among the readings (SD=7.55). CONCLUSION: Ring-less system of casting can be recommended for use in fabricating implant supported fixed dental restorations.

Effect of water temperature and duration of immersion on the marginal accuracy of provisional crowns.

BACKGROUND: Fabrication of fixed restorations is time consuming. It is vital that the prepared teeth be protected by means of an interim restoration till the time definitive prostheses can be delivered. Marginal adaptation is one of the most important requirements for an interim restoration. METHOD: This study was done to investigate the effect of water temperature and duration of immersion on the marginal accuracy of provisional restoration fabricated in autopolymerizing resin. The experimental model simulating a clinical situation was made. The test material was autopolymerizing methyl methacrylate. Specimens were subjected to different water temperatures for 5 and 10 minutes', duration for continuing the polymerization. Marginal accuracy was determined by a travelling microscope under 100 × magnification. RESULTS: The measurements were tabulated and statistically analyzed using two way ANOVA technique. Results showed significant difference at all water temperatures. Marginal gaps were least when crowns were polymerized at 20°C for 5 minutes. CONCLUSION: Study concluded that polymerizing the polymethyl methacrylate resin provisional crowns by direct technique in the water maintained at 20-30°C temperature for 10 minutes resulted in better marginal fit and this method can be utilized in clinical conditions for better results.

An evaluation of fracture resistance of interim fixed partial denture fabricated using polymethylmethacrylate and reinforced by different fibres for its optimal placement: an in vitro study.

BACKGROUND: Polymethylmethacrylate (PMMA) is the most common material used to fabricate interim fixed partial denture (FPD). Several attempts have been made to improve fracture strength of this material with various methods of reinforcement, but its effect on the fracture resistance of interim FPD was not evaluated. METHOD: The study was designed in two stages. In the first stage various methods of reinforcement (glass fibre, polyethylene, combination of glass and polyethylene, and stainless steel) for interim FPD of PMMA were used and its effect on the fracture resistance of interim FPD was evaluated by three point bending test using universal testing machine. In the second stage, fibres which showed the highest fracture resistance value was used to ascertain the most appropriate site of placement for reinforcing interim FPD. Comparisons were made with analysis of variance. RESULTS: Stainless steel and glass fibres showed significantly higher fracture resistance value than polyethylene alone or mixed with glass fibres (P < 0.001). Fibre placement in the occlusal third region of the pontic resulted in higher fracture resistance than the other locations (P < 0.05). CONCLUSION: There was a definite improvement in the fracture resistance after reinforcement with fibres and stainless steel. The occlusal third region of the pontic is the most appropriate site of placement for reinforcement in interim FPD.