Evaluation of the Efficacy of Minimal Invasive Methods Versus Conventional Methods for Caries Removal in Primary Molars

AIM

Evaluating the efficacy of two "minimal invasive methods" of caries removal (Brix 3000/ceramic bur) in comparison with the conventional method in the management of dental caries in primary molars.  Materials and methods: A sum of 60 teeth from children ranging from four to nine years old of both sexes were selected for this study and randomly assigned to three groups: Group I (Brix 3000), Group II (ceramic bur), and Group III (diamond bur), with 20 teeth per group.

RESULTS

Regarding the efficacy of caries removal, the Brix 3000 group had significantly the lowest efficacy, while the ceramic bur and diamond bur groups were significantly the highest without significant differences between the ceramic and diamond groups. Regarding caries removal time, the Brix 3000 group was significantly the highest, while the diamond bur group was significantly the lowest, and the ceramic bur group was intermediate between them. Regarding pain perception, the Brix 3000 and ceramic bur groups were significantly the lowest, with insignificant differences between them, while the diamond bur group was significantly the highest.

CONCLUSION

Ceramic bur is an excellent alternative treatment for caries removal in children in comparison with conventional methods and CMCR. Brix 3000®, despite being less painful in comparison with drilling methods, has lower efficacy and efficiency.

Gas-phase microactuation using kinetically controlled surface states of ultrathin catalytic sheets

Biological systems convert chemical energy into mechanical work by using protein catalysts that assume kinetically controlled conformational states. Synthetic chemomechanical systems using chemical catalysis have been reported, but they are slow, require high temperatures to operate, or indirectly perform work by harnessing reaction products in liquids (e.g., heat or protons). Here, we introduce a bioinspired chemical strategy for gas-phase chemomechanical transduction that sequences the elementary steps of catalytic reactions on ultrathin (<10 nm) platinum sheets to generate surface stresses that directly drive microactuation (bending radii of 700 nm) at ambient conditions (T = 20 °C; Ptotal = 1 atm). When fueled by hydrogen gas and either oxygen or ozone gas, we show how kinetically controlled surface states of the catalyst can be exploited to achieve fast actuation (600 ms/cycle) at 20 °C. We also show that the approach can integrate photochemically controlled reactions and can be used to drive the reconfiguration of microhinges and complex origami- and kirigami-based microstructures.

Physicochemical and Mechanical Effects of Commercial Silver Diamine Fluoride (SDF) Agents on Demineralized Dentin

PURPOSE

To investigate the effects of four commercial silver diamine fluoride (SDF) agents on the chemical composition and microstructural properties of dentin, and its relation to the bond strength of two adhesives.

MATERIALS AND METHODS

Ninety human molars were randomly divided into sound dentin (negative control), demineralized dentin (positive control), and four experimental groups (n = 15) according to the SDF treatments (Cariestop [Biodinamica Quimica y Farmaceutica], RivaStar 1 [SDI], RivaStar 2 [SDI], and Saforide [Tokyo Seiyaku Kasei]). ATR-FTIR, x-ray diffraction, and SEM techniques were employed to characterize the compositional, crystalline, and microstructural properties of the samples. The microtensile bond strength test evaluated the bonding performance of two adhesives in demineralized dentin treated with SDF agents.

RESULTS

Regarding the chemical composition, all SDF-treated groups showed a significantly higher phosphate:organic matrix ratio than the demineralized dentin group (p < 0.05). The XRD analyses revealed that the crystallite size for hydroxyapatite crystals increased on the surface areas (deep, medium, and superficial dentin) for all experimental groups compared to demineralized dentin (p < 0.05). SEM images showed that the behavior of the agents used differs on each surface treated. Bond strength values were adversely affected with both adhesive systems in the four experimental groups (p < 0.05).

CONCLUSIONS

The application of SDF agents resulted in the formation of different crystalline phases of silver salts and the increase of mineralization of the pretreated demineralized dentin. However, SDF application showed a negative effect on the bond strength of the adhesives.

Chemomechanically Stable Ultrahigh-Ni Single-Crystalline Cathodes with Improved Oxygen Retention and Delayed Phase Degradations

The pressing demand in electrical vehicle (EV) markets for high-energy-density lithium-ion batteries (LIBs) requires further increasing the Ni content in high-Ni and low-Co cathodes. However, the commercialization of high-Ni cathodes is hindered by their intrinsic chemomechanical instabilities and fast capacity fade. The emerging single-crystalline strategy offers a promising solution, yet the operation and degradation mechanism of single-crystalline cathodes remain elusive, especially in the extremely challenging ultrahigh-Ni (Ni > 90%) regime whereby the phase transformation, oxygen loss, and mechanical instability are exacerbated with increased Ni content. Herein, we decipher the atomic-scale stabilization mechanism controlling the enhanced cycling performance of an ultrahigh-Ni single-crystalline cathode. We find that the charge/discharge inhomogeneity, the intergranular cracking, and oxygen-loss-related phase degradations that are prominent in ultrahigh-Ni polycrystalline cathodes are considerably suppressed in their single-crystalline counterparts, leading to improved chemomechanical and cycling stabilities of the single-crystalline cathodes. Our work offers important guidance for designing next-generation single-crystalline cathodes for high-capacity, long-life LIBs.

Systematic review on alternative methods for caries removal in permanent teeth

Introduction:

Dental caries is the most common chronic dental disease in the world. It is defined as a multifactorial microbial infectious disease characterized by demineralization of the inorganic and destruction of the organic substance of the tooth. The host, flora, and the substrate should be there for the formation of dental caries. There are various microorganisms responsible for caries. The treatment for caries is essential to prevent teeth from involving pulp, leading to further damage. There are various methods in removing caries such as minimally invasive technique, rotary method with different types of burs, chemomechanical caries removal, and lasers. There are no data in literature for various methods of removing caries in permanent teeth.

Materials and Methods:

Research question was formulated based on the PICO strategy. A comprehensive electronic literature search was conducted, independently by two reviewers. Based on the specified inclusion and exclusion criteria's, the selected articles were subjected to quality assessment and the risk of bias was evaluated.

Objective:

The objective of this study was to evaluate the efficiency of caries removal by various methods in permanent teeth.

Search Strategy:

A search was performed in electronic database (i.e. PubMed and Medline) using search terms alone and in combination by means of PubMed search builder from January 1985 to January 2018.

Selection Criteria:

Studies were selected if they met the following criteria: in vivo studies comparing various methods of caries removal in permanent teeth.

Results:

The search identified 338 publications, out of which 328 were excluded after examination of the title and 2 were excluded after examination of the abstract. Through the hand search, three articles were included. Eight articles were retrieved for more detailed evaluation from the search. A total of 11 publications fulfilled all the criteria for inclusion.

Conclusion:

With the available evidence, this review concludes that the studies included in this review have a high risk of quality evidence.

Antimicrobial activity of chemomechanical gingival retraction products

BACKGROUND

Application of astringent hemostatic agents is the most widely used technique for gingival retraction, and a variety of products are offered commercially. However, these products may have additional unintended yet clinically beneficial properties. The authors assessed the antimicrobial activities of marketed retraction products against plaque-associated bacteria in both planktonic and biofilm assays, in vitro.

METHODS

The authors assessed hemostatic solutions, gels, pellets, retraction cords, pastes, and their listed active agents against a collection of microorganisms by means of conventional agar diffusion and minimum bacteriostatic and bactericidal concentration determinations. The authors then tested the most active products against monospecies biofilms grown on hydroxyapatite disks.

RESULTS

All of the tested retraction products exhibited some antimicrobial activity. The results of the most active products were comparable with those of a marketed mouthwash. The listed retraction-active agents displayed relatively little activity when tested in pure form. At 10% dilution, some products evidenced inhibitory activity against most tested bacteria within 3 minutes of exposure, whereas others displayed variable effects after 10 minutes. The most active agents reduced, but did not completely prevent, the metabolic activity of a monospecies biofilm.

CONCLUSIONS

Commercial gingival retraction products exhibit antimicrobial effects to various degrees in vitro. Some products display rapid bactericidal activity. The antimicrobial activity is not owing to the retraction-active agents. Biofilm bacteria are less sensitive to the antimicrobial effects of the agents.

PRACTICAL IMPLICATIONS

The rapidity of killing by some hemostatic agents suggests an antimicrobial effect that may be efficacious during clinical placement. The results of this in vitro study suggest that clinicians should be aware of the potential antimicrobial effects of some hemostatic agents, but more research is needed to confirm these observations in clinical use.

Rotary Drill: A Systematic Review

Background:

Chemomechanical caries removal is an effective alternative to the traditional rotary drilling method. The advantages of chemomechanical techniques in terms of the need for anesthesia, pain perception and patient preference are systematically reviewed and a meta-analysis of the time required for caries removal is reported.

Method:

Randomized controlled studies of comparison of chemomechanical techniques with conventional rotary drill were selected from a systematic search of standard biomedical databases, including the PubMed and Cochrane clinical trials. Non-repeated search results were screened for relevance and risk of bias assessment, followed by methodology assessment. Statistical models were applied to the outcome parameters - time required, pain perception, need of anesthesia and patient preference - extracted from the studies.

Results:

Out of the 111 non-repeated search results, 26 studies receiving a low bias score were selected for the review, and 16 randomized clinical trials of rotary and Carisolv techniques were considered for meta-analysis. Meta-analysis by fixed effect as well as random effect models indicate that Carisolv takes more time (3.65 ± 0.05 and 4.09 ± 0.29 min) than rotary drill (8.65 ± 0.09 and 8.97 ± 0.66 min) method. Advantages of reduced pain (14.67 for Carisolv vs. 6.76 for rotary drill), need for anesthesia (1.59% vs. 10.52%) outweigh the longer time requirement and make it the preferred (18.68% vs. 4.69%) method.

Conclusion:

Chemomechanical techniques stand out as a minimally invasive and preferred method based on the meta-analyses. Evaluation of pain experienced using robust methods is needed to strengthen the evidence for their use.