Cavitation occurs around dental ultrasonic scalers, which are used clinically for removing dental biofilm and calculus. However it is not known if this contributes to the cleaning process. ...Characterisation of the cavitation around ultrasonic scalers will assist in assessing its contribution and in developing new clinical devices for removing biofilm with cavitation. The aim is to use high speed camera imaging to quantify cavitation patterns around an ultrasonic scaler. A Satelec ultrasonic scaler operating at 29 kHz with three different shaped tips has been studied at medium and high operating power using high speed imaging at 15,000, 90,000 and 250,000 frames per second. The tip displacement has been recorded using scanning laser vibrometry. Cavitation occurs at the free end of the tip and increases with power while the area and width of the cavitation cloud varies for different shaped tips. The cavitation starts at the antinodes, with little or no cavitation at the node. High speed image sequences combined with scanning laser vibrometry show individual microbubbles imploding and bubble clouds lifting and moving away from the ultrasonic scaler tip, with larger tip displacement causing more cavitation.
Bacterial biofilms are a cause of contamination in a wide range of medical and biological areas. Ultrasound is a mechanical energy that can remove these biofilms using cavitation and acoustic ...streaming, which generate shear forces to disrupt biofilm from a surface. The aim of this narrative review is to investigate the literature on the mechanical removal of biofilm using acoustic cavitation to identify the different operating parameters affecting its removal using this method. The properties of the liquid and the properties of the ultrasound have a large impact on the type of cavitation generated. These include gas content, temperature, surface tension, frequency of ultrasound and acoustic pressure. For many of these parameters, more research is required to understand their mechanisms in the area of ultrasonic biofilm removal, and further research will help to optimise this method for effective removal of biofilms from different surfaces.
Quantifying biofilm formation on surfaces is challenging because traditional microbiological methods, such as total colony-forming units (CFUs), often rely on manual counting. These are laborious, ...resource intensive techniques, more susceptible to human error. Confocal laser scanning microscopy (CLSM) is a high-resolution technique that allows 3D visualisation of biofilm architecture. In combination with a live/dead stain, it can be used to quantify biofilm viability on both transparent and opaque surfaces. However, there is little consensus on the appropriate methodology to apply in confocal micrograph processing. In this study, we report the development of an image analysis approach to repeatably quantify biofilm viability and surface coverage. We also demonstrate its use for a range of bacterial species and translational applications. This protocol has been created with ease of use and accessibility in mind, to enable researchers who do not specialise in computational techniques to be confident in applying these methods to analyse biofilm micrographs. Furthermore, the simplicity of the method enables the user to adapt it for their bespoke needs. Validation experiments demonstrate the automated analysis is robust and accurate across a range of bacterial species and an improvement on traditional microbiological analysis. Furthermore, application to translational case studies show the automated method is a reliable measurement of biomass and cell viability. This approach will ensure image analysis is an accessible option for those in the microbiology and biomaterials field, improve current detection approaches and ultimately support the development of novel strategies for preventing biofilm formation by ensuring comparability across studies.
Current instruments cannot clean in between dental implant threads and effectively remove biofilm from the rough implant surface without damaging it. Cavitation bubbles have the potential to disrupt ...biofilms. The aim of this study was to see how biofilms can be disrupted using non-contact cavitation from an ultrasonic scaler, imaged inside a restricted implant pocket model using high speed imaging.
Streptococcus sanguinis biofilm was grown for 7 days on dental implants. The implants were placed inside a custom made restricted pocket model and immersed inside a water tank. An ultrasonic scaler tip was placed 0.5mm away from the implant surface and operated at medium power or high power for 2s. The biofilm removal process was imaged using a high speed camera operating at 500 fps. Image analysis was used to calculate the amount of biofilm removed from the high speed images. Scanning electron microscopy was done to visualize the implant surface after cleaning.
Cavitation was able to remove biofilm from dental implants. More biofilm was removed at high power. Scanning electron microscopy showed that the implant surface was clean at the points where the cavitation was most intense. High speed imaging showed biofilm removal underneath implant threads, in areas next to the ultrasonic scaler tip.
A high speed imaging protocol has been developed to visualize and quantify biofilm removal from dental implants in vitro. Cavitation bubbles from dental ultrasonic scalers are able to successfully disrupt biofilm in between implant threads.
Co-cultures allow for the study of cell-cell interactions between different eukaryotic species or with bacteria. Such an approach has enabled researchers to more closely mimic complex tissue ...structures. This review is focused on co-culture systems modelling the oral cavity, which have been used to evaluate this unique cellular environment and understand disease progression. Over time, these systems have developed significantly from simple 2D eukaryotic cultures and planktonic bacteria to more complex 3D tissue engineered structures and biofilms. Careful selection and design of the co-culture along with critical parameters, such as seeding density and choice of analysis method, have resulted in several advances. This review provides a comparison of existing co-culture systems for the oral environment, with emphasis on progression of 3D models and the opportunity to harness techniques from other fields to improve current methods. While filling a gap in navigating this literature, this review ultimately supports the development of this vital technique in the field of oral biology.
We have cultured and phenotyped human adipose tissue-derived mesenchymal stem/stromal cells (AT MSCs) and inoculated these cultures with bacteria common to infected skin wounds, i.e. Staphylococcus ...aureus and Pseudomonas aeruginosa. Cell interactions were examined by scanning electron microscopy (SEM), whilst bacterial growth was measured by colony forming unit (c.f.u.) and biofilm assays. AT MSCs appeared to attach to the bacteria and to engulf S. aureus. Significantly fewer bacterial c.f.u. were present in AT MSC : bacterial co-cultures compared with bacteria cultured alone. Antibacterial activity, including an inhibition of P. aeruginosa biofilm formation, was observed when bacteria were treated with conditioned medium harvested from the AT MSC : bacterial co-cultures, irrespective of the bacterial species to which the AT MSCs had been exposed to previously. Hence, we have demonstrated that AT MSCs inhibit the growth of two common bacterial species. This was associated with bacterial adhesion, potential engulfment or phagocytosis, and the secretion of antibacterial factors.
To evaluate the outcome of narrow-diameter (3.3-mm) locking-taper implants used in the rehabilitation of partially and fully edentulous patients over a 10-year period.
Between January 2002 and ...December 2011, all patients referred to a private dental clinic for treatment with narrow-diameter implants were enrolled in this study. At each annual follow-up session, clinical and radiographic parameters were assessed; the outcome measurements were implant failure, peri-implant marginal bone loss (distance between the implant shoulder and the first visible bone-to-implant contact DIB), and biologic and technical complications. The cumulative survival rate (CSR) was assessed using the Kaplan-Meier survival estimator; Tarone-Ware and chi-square analyses were used to evaluate correlations between the study variables. The statistical analysis was performed at the patient- and implant-level.
A total of 324 narrow-diameter implants were placed in 279 patients (159 men, 120 women; age: 25 to 73 years). Four implants failed, for an overall CSR of 98.5% (patient-based) and 98.7% (implant-based) at the 10-year follow-up. The survival rate did not differ significantly with respect to patients' sex, age, smoking or parafunctional habits, bone type, prosthetic restoration, or implant location, position, or length. Among the surviving implants, a mean DIB of 0.31 ± 0.23 mm, 0.45 ± 0.27 mm, and 0.69 ± 0.28 mm was observed at the 1-, 5-, and 10-year follow-up examinations, respectively. A few biologic (1.2%) and technical complications (7.5%) were reported.
Within the limitations of this study, it can be concluded that narrow-diameter locking-taper implants represent a good treatment option for the prosthetic rehabilitation of partially and totally edentulous patients.
To compare interactions between rat calvarial osteoblasts and titanium dental implants with different microstructured surfaces.
Seven commercially available implants were used. Surfaces included ...plasma-sprayed, grit-blasted and/or acid-etched, smooth-machined and anodised titanium. Two methods were used to compare cell behaviour: (1) A cell-spreading assay in which percentages of cells at four different stages of attachment were identified by scanning electron microscopy and quantified within a 30 min attachment period. (2) Implants were placed in 'pocket culture' within nylon mesh sacs in contact with explanted calvarial bone fragments for 2 and 4 weeks.
Surfaces combining grit blasting and acid etching, of microporous topography, showed significantly enhanced rates of cell spreading in comparison with the others. Differential cell morphology was observed in both suspension assays and pocket cultures. In the latter, cells migrated onto all surfaces. Multicellular layers with extracellular matrix (ECM) were present between the layers and on the material surfaces after 2 weeks. After 4 weeks, cell layers were more consolidated, and microstructures were obscured by layers of cells and ECM. Mineralised tissue was seen in association with ECM on grit-blasted surfaces of rough and smooth microtopography.
The two methods provided complementary information: a rough surface of porous microstructure may enhance the rate of cell spreading. Differentiation and calcification occurred on surfaces of both rough and smooth microstructure.
The aim of this study is to evaluate the implant survival, the implant-crown success, and the prosthetic complications of 2,549 Morse taper interference-fit connection implants.
A total of 2,549 ...Morse taper connection implants were inserted in 893 patients from January 2003 until December 2008. At each annual recall, clinical, radiographic, and prosthetic parameters were assessed. The implant-crown success criteria included the absence of pain, suppuration, and clinical mobility; an average distance between the implant shoulder and the first visible bone contact <2 mm from initial surgery; and the absence of prosthetic complications at the implant-abutment interface. Prosthetic restorations were fixed partial prostheses (462 units); fixed full-arch prostheses (60 units); single crowns (531 units); and overdentures (93 units).
The cumulative implant survival rate was 98.23% (97.25% maxilla, 99.05% mandible). The implant-crown success was 92.49%. A few prosthetic complications at implant-abutment interface were reported (0.37%). After 6 years, distance between the implant shoulder and the first visible bone contact was 1.10 mm (± 0.30 mm).
The use of Morse taper connection implants represents a successful procedure for the rehabilitation of partially and completely edentulous arches.
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