Valorization of Seaweed: Using Brown Algae Waste in Papermaking

In this work, the brown alga Dictyota dichotoma was explored as a new reinforcing material for papermaking. Performing the typical chemical tests for cellulosic substrates on D. dichotoma evidenced large amounts of ethanol:benzene extractable substances (7.2%) and ashes, algae-specific results. Also, even if lipophilic compounds are removed, brown seaweed are not a primary source of fibers because it contains low proportion of cellulose. However, its elevated content of insoluble carbohydrates (51.4%) suggest there is some potential in association with conventional cellulosic pulps, as fibrous elements contribute to sheet forming and other components fill the spaces in the paper web without noteworthy loss of strength. Extraction was carried out with clean processes: hydrogen peroxide and mixtures (hydrogen peroxide-hydrochloric acid and hydrogen peroxide-sodium perborate), sodium hydroxide and sodium hypochlorite, always aiming for low reagent concentrations, in the range of 1-12%. The results show that sodium hydroxide and sodium hypochlorite were the treatments that lead to paper sheets with better structural and mechanical properties without further bleaching or refining, thus highlighting the suitability of these algae for papermaking applications.

Minimally Invasive Multidisciplinary Restorative Approach to the Esthetic Zone Including a Single Discolored Tooth

SUMMARY Objectives: The case report describes a minimally invasive, multidisciplinary approach to a single discolored anterior tooth, with internal bleaching using traditional Japanese paper (Washi), a gingivoplasty with a three-dimensional (3D) printed surgical guide, and ultrathin feldspathic porcelain veneers. Clinical consideration: The patient’s primary concern was improving her smile. After clinical evaluation, internal tooth bleaching for the discolored tooth and gingivoplasty with restoration of the maxillary anterior six teeth and first premolars was recommended. The internal tooth whitening was accomplished with sodium perborate mixed with 30% hydrogen peroxide impregnated in Washi and sealed in the root canal with glass ionomer. Once the tooth bleaching was completed, the 3D printed surgical guide was placed in the patient’s maxillary anterior region and used to guide soft tissue recontouring. After 6 months, ultrathin feldspathic porcelain veneers were placed. Conclusion: Well-planned restorative procedures combining internal tooth bleaching using Washi, gingivoplasty performed with electrosurgery using a 3D printed surgical guide, and ultrathin feldspathic porcelain veneers can achieve the desired results in the esthetic zone and remain successful for 4 years.

Prerequisites to Use Preservative-Free Drugs in Medication Therapy of Glaucoma

Purpose — to analyze the literature data on the benefits of preservative-free medication therapy for glaucoma.Materials and methods. 482 articles in the Pubmed database published from 1975 to 2020 were analyzed using the terms: “glaucoma”, “preservatives”, “preservative-free therapy”, “benzalkonium chloride”. The review includes 78 articles. Inclusion criteria: studies that examined the effect of local antihypertensive therapy on the condition of the ocular surface in comparison with preservative-free drugs.Discussion. BAC is the most common preservative used in ophthalmology, accounting for 70 % of eye drop formulations. But it has a pronounced toxic effect on the ocular surface, so other classes of preservatives have been developed. These include polyquaternium-1 detergent; oxidizing preservatives — stabilized oxychlorocomplex and sodium perborate; ionic buffer preservative. However, most of the publications are devoted to BAC, as it is considered the most toxic and, at the same time, the most commonly used preservative. There is a large number of switching studies from preservative therapy to preservative-free, in which almost all groups of drugs used for the treatment of glaucoma were studied, but the use of antihypertensive drugs is associated not only with the action of preservatives, but also with the active substance, excipients and buffers. However, most switching studies demonstrate the benefits of preservative-free drugs. Other studies compared preservative and preservative-free drugs with the same active ingredients, in which a comparable hypotensive effect and safety profile was revealed, which indicates that BAC is not required for adequate penetration of the active substance to the point of application. At the same time, statistically significant advantages in the tolerability of preservativefree therapy were also revealed.Conclusion. Glaucoma preservative therapy has a toxic effect on the ocular surface, which leads to a decrease in the quality of life and compliance. Switching to preservative-free drugs can help reduce iatrogenic complications during long-term treatment of patients with glaucoma

Influence of Irrigation Protocol on Peroxide Penetration into Dentinal Tubules Following Internal Bleaching: A Confocal Laser Scanning Microscopy Study

Introduction: Discoloration of anterior teeth can result in cosmetic impairment in young children. The walking bleach technique stands out because of its esthetic results with minor side effects. Little information is available regarding the influence of various irrigation solutions on peroxide penetration. The aim of this study is to evaluate the influence of different irrigation protocols on peroxide penetration into dentinal tubules using confocal laser scanning microscopy (CLSM). Study design: Cavity preparations were made in 50 extracted permanent premolars. The teeth went through different irrigation sequences: A. control B. saline C. EDTA, NaOCl D. phosphoric acid E. EDTA, NaOCl, phosphoric acid. Then, mixture of fluorescent dyed sodium perborate paste was placed along the pulp chamber and the coronal access cavity, and was refilled at days 7, 14 and 21. Results: The minimal and maximal penetration depths were 324 and 3045 μm, respectively, with a mean of 1607μm. The stained areas were significantly larger in the buccal and lingual directions (P<0.05). Groups B and C showed significantly larger penetration in weeks 2 and 3 compared to week 1 (P<0.05). Group D and E showed significantly larger penetration compared to groups B and C at all times (P<0.05). Conclusion: Bleaching agents penetrate to the extra-radicular region of teeth; however, the level of peroxide penetration is significantly higher when the irrigation sequence consists of phosphoric acid prior the bleaching agent placement.

Management of non-vital maxillary central incisor with intrinsic discoloration using walking bleach technique

Non-vital bleaching is a non-invasive technique for the treatment of intrinsic discoloration of teeth. Hydrogen peroxide and sodium perborate are commonly used bleaching agents. The aim of this case report is to demonstrate the non-vital bleaching technique in maxillary anterior teeth. Maxillary central incisors were isolated and root canal treatment was performed. Barrier space preparation was done using a heated instrument. Glass ionomer cement was used a barrier material. Mixture of hydrogen peroxide was placed in the canal and sealed with intermediate restorative material. After 1 week, the procedure was repeated to achieve the desired results. Non-vital bleaching is a minimally invasive procedure to restore the esthetics of a discoloured non-vital tooth. However, care should be taken to prevent any post-operative complications.

Dentists’ preference for Vital and Non-vital Tooth Bleaching Material in Teaching Institutions of Multan

Objective: The objective of this study was three fold; to investigate the preference of dentists regarding the technique for vital and non-vital tooth bleaching, to find out the materials used for vital and non-vital tooth bleaching and to evaluate the influence of post-graduate training, working place and clinical experience on techniques and material used. Methodology: A cross sectional study was carried out using a questionnaire with dentists working in three teaching institutes of Multan, Nishtar Institute of Dentistry (NID), Bakhtawar Amin Medical & Dental College (BAMDC) and Multan Medical & Dental College (MMDC). A total of 170 questionnaires were distributed and 154 recovered, at a response rate of 90.5%. Information about post-graduate training, working place and clinical experience was obtained. The information regarding technique and material used for vital and non-vital tooth bleaching was also collected. Data were analyzed using SPSS version 22 and frequencies and percentages were calculated along with association between the treatment options and other variables. Results: Majority of the dentists 81.8% and 75.3% preferred in-office technique for vital and non-vital tooth bleaching respectively. For vital tooth bleaching, 31.8% selected HP 6% and 28.4% opted CP10-22%. For non-vital tooth bleaching, 34.8% selected SP mixed with water/HP and 26.6% opted HP37%. Conclusion: Clinical experience and working place significantly influenced the bleaching technique for vital teeth not for the non-vital. No significant influence of post-graduation, clinical experience and working place was found on material used for vital or non-vital bleaching. Key Words: Vital tooth bleaching, Non-vital tooth bleaching, Hydrogen peroxide, Carbamide peroxide, Sodium perborate

Assessment of Oxygen Expansion during Internal Bleaching with Enamel and Dentin: A Comparative In Vitro Study

Internal bleaching is a conservative, non-invasive, and simple treatment that is frequently performed in daily clinical practice. The present in vitro study analyzes the oxygen expansion of different bleaching agents resulting from the oxidation reaction when interacting with enamel and dentin. Enamel and dentin were crushed separately until obtaining a fine powder with particles of an approximate size between 0.06 and 0.2 mm. Each enamel and dentin sample were mixed with 37% carbamide peroxide (CP 37%), 30% hydrogen peroxide (HP 30%), sodium perborate (SP) combined with HP 30% (HP 30% + SP) and SP with distilled water (SP). A total of 280 1 mm diameter glass tubes were used with 70 for each bleaching agent (30 for powdered enamel evaluation, 30 for powdered dentin evaluation, and 10 controls). The bleaching agents were placed in the prepared tubes immediately after mixing the components. As expansion occurred, the oil inside the tube was displaced, through which the resulting expansion was evaluated and measured for 10 days. A significant expansion was observed that varied in magnitude according to the bleaching agent and the tooth structure used. Student’s t test and Welch’s ANOVA were used to analyze the data obtained. The highest mean expansion of both enamel and dentin was observed with 30% HP (66.6 mm for enamel, 94.5 mm for dentin) followed by HP 30% + SP (48.6 mm for enamel, 52.7 mm for dentin), CP 37% (38.4 mm for enamel, 52.6 mm for dentin) and finally SP with water (12.7 mm for enamel, 4.4 mm for dentin). It was observed that the expansion in the SP group with enamel was significantly lower than in the rest of the groups, while that registered for HP 30% was significantly higher. (p < 0.001). The results with dentin were similar, with a significantly lower expansion for SP and higher for HP 30% (p < 0.001). The oxygen expansion observed as a result of the interaction between bleaching agents and dental tissues could contribute to improving our understanding of bleaching and its results. These results suggest that bleaching agents react with the organic component of the tooth structure.

Spectrophotometric analysis of internal bleaching of traumatized teeth with coronal discoloration following regenerative endodontic procedures

Aim: The objective of this study was to describe a case series concerning internal bleaching of anterior traumatized teeth that underwent regenerative endodontic procedures (REP). Methods: Seven non-vital maxillary anterior teeth discolored after regenerative endodontic procedures were included and divided into two groups according to the medication protocol used in the REP: (1) Triple antibiotic paste (TAP) group (n=4); (2) Calcium hydroxide and 2% chlorhexidine gel (HC+CHX) (n=3). The bleaching technique used was walking bleach, where sodium perborate associated with distilled water was used. Bleaching agent was replaced weekly until the darkened tooth was slightly lighter than the adjacent tooth. The color was recorded with the aid of a digital spectrophotometer in two moments (T1: prior the first session of bleaching, T2: fourteen days after the last session of bleaching). The change in color after the procedure (ΔE) was calculated and reported in a descriptive analysis. Results: The ΔE for all teeth showed color differences exceeding the perceptibility threshold (ΔE > 3.7). Both groups showed similar ΔE (TAP: 18.3 ± 11.5; HC+CHX: 14 ± 11.2) at the end of the treatment. The average number of sessions needed to achieve satisfactory results was 1.7 ± 0.6 for HC+CHX group and 2.3 ± 0.5 for TAP group. Conclusion: Internal bleaching with sodium perborate associated with distilled water is effective in treating discolored teeth after regenerative endodontic procedures.

Efficacy of Carbamide Peroxide and Sodium Perborate as Bleaching Agent in Non-Vital Discolored Teeth

To estimate the effectiveness of sodium perborate with carbamide-peroxide (urea peroxide) to remove the staining of non-vital discolored teeth. Comparative cross sectional study. Dental department of operative dentistry, LUMHS, Jamshoro Sindh, Pakistan, from December 15-12-2014 to June 15-6-2015. A total of 160 single rooted teeth with intact clinical crowns have been collected. Using human blood, the teeth were discolored. With the vita shade guide, shades of discolored teeth were taken. Each tooth was handled with the root canal. 2 mm of root-canal-filling material cleaned under the junction of cement-enamel. In addition, it was then coated with glass ionomer cement 1 mm thickness. Teeth were divided randomly into two groups based on bleaching content used in the pulp chamber; group-A (C.P): 16% Carbamide-peroxide. Group-B (S.P): tetra-hydrate sodium-perborate mixed with distilled water. After 21days, the results were checked for efficacy. The analysis included a total of 160 teeth extracted (80 teeth extracted in each group). In group A, 78 (51.7%) found effectiveness compared to 73 (48.3%) in group B. The experimental groups showed statistically similar bleaching results at the end of twenty one days and p value found to be not significantly different (p=0.078). With a significant result, intracoronal bleaching of non-vital colored teeth is less invasive, comparatively safe and effective to remove the staining of non-vital discolored teeth.