Adsorption and wettability study of methyl ester sulphonate on precipitated asphaltene

Asphaltene precipitation from crude oil and its subsequent aggregation forms solid, which preferentially deposit on rock surfaces causing formation damage and wettability changes leading to loss of crude oil production. To resolve this problem, asphaltene inhibitor has been injected into the formation to prevent the precipitation of asphaltene. Asphaltene inhibitors that are usually employed are generally toxic and non-biodegradable. This paper presents a new environmentally friendly asphaltene inhibitor (methyl ester sulphonate), an anionic surfactant, which has excellent sorption on formation rock surfaces. Result from adsorption study validated by Langmuir and Freundlich models indicate a favourable adsorption. At low volumes injected, methyl ester sulphonate is capable of reverting oil-wet sandstone surface to water-wet surface. Biodegradability test profile shows that for concentrations of 100-5000ppm it is biodegradable by 65-80%

Oral biofilm models for mechanical plaque removal

In vitro plaque removal studies require biofilm models that resemble in vivo dental plaque. Here, we compare contact and non-contact removal of single and dual-species biofilms as well as of biofilms grown from human whole saliva in vitro using different biofilm models. Bacteria were adhered to a salivary pellicle for 2 h or grown after adhesion for 16 h, after which, their removal was evaluated. In a contact mode, no differences were observed between the manual, rotating, or sonic brushing; and removal was on average 39%, 84%, and 95% for Streptococcus mutans, Streptococcus oralis, and Actinomyces naeslundii, respectively, and 90% and 54% for the dual- and multi-species biofilms, respectively. However, in a non-contact mode, rotating and sonic brushes still removed considerable numbers of bacteria (24–40%), while the manual brush as a control (5–11%) did not. Single A. naeslundii and dual-species (A. naeslundii and S. oralis) biofilms were more difficult to remove after 16 h growth than after 2 h adhesion (on average, 62% and 93% for 16- and 2-h-old biofilms, respectively), while in contrast, biofilms grown from whole saliva were easier to remove (97% after 16 h and 54% after 2 h of growth). Considering the strong adhesion of dual-species biofilms and their easier more reproducible growth compared with biofilms grown from whole saliva, dual-species biofilms of A. naeslundii and S. oralis are suggested to be preferred for use in mechanical plaque removal studies in vitro

How effective is a powered toothbrush as compared to a manual toothbrush? A systematic review and meta‐analysis of single brushing exercises

Objectives: In adult participants, what is, following a single brushing exercise, the efficacy of a powered toothbrush (PTB) as compared to a manual toothbrush (MTB) on plaque removal?. Methods: MEDLINE-PubMed and Cochrane-CENTRAL were searched from inception to February 2019. The inclusion criteria were (randomized) controlled clinical trials conducted in human subjects ≥18 years of age, in good general health and without periodontitis, orthodontic treatment, implants and/or removable prosthesis. Papers evaluating a PTB compared with a MTB in a single brushing exercise were included. When plaque scores were assessed according to the Quigley-Hein plaque index (Q&HPI) or the Rustogi modified Navy plaque index (RMNPI). From the eligible studies, data were extracted. A meta-analysis and subanalysis for brands and mode of action being oscillating-rotating (OR) and side-to-side (SS) were performed when feasible. Results: Independent screening of 3450 unique papers resulted in 17 eligible publications presenting 36 comparisons. In total, 28 comparisons assessed toothbrushing efficacy according to the Q&HPI and eight comparisons used the RMNPI. Results showed a significant effect in favour of the PTB. The difference of Means (DiffM) was −0.14 (P < 0.001; 95%CI [−0.19; −0.09]) for the Q&HPI and −0.10 (P < 0.001; 95%CI [−0.14; −0.06]) for the RMNPI, respectively. The subanalysis on the OR mode of action showed a DiffM −0.16 (P < 0.001; 95%CI [−0.22, −0.10]) for the Q&HPI. For the SS mode of action using RMNPI, the DiffM showed −0.10 (P < 0.001; 95%CI [−0.15; −0.05]). The subanalysis for brands showed for the P&G OR PTB using the Q&HPI a DiffM of −0.15 (P < 0.001; 95%CI [−0.22; −0.08]) and the Colgate SS for RMNPI showed a DiffM of −0.15 (P < 0.001; 95%CI [−0.18; −0.12]). Conclusion: There is moderate certainty that the PTB was more effective than the MTB with respect to plaque removal following a single brushing exercise independent of the plaque index scale that was used