Dental Materials Research Articles

Synthesis of polymerizable betulin maleic diester derivative for dental restorative resins with antibacterial activity

ObjectiveBisphenol A glycidyl methacrylate (Bis-GMA) is of great importance for dental materials as the preferred monomer. However, the presence of bisphenol-A (BPA) core in Bis-GMA structure causes potential concerns since it is associated with endocrine diseases, developmental abnormalities, and cancer lesions. Therefore, it is desirable to develop an alternative replacement for Bis-GMA and explore the intrinsic relationship between monomer structure and resin properties. MethodsHere, the betulin maleic diester derivative (MABet) was synthesized by a facile esterification reaction using plant-derived betulin and maleic anhydride as raw materials. Its chemical structure was confirmed by 1H and 13C NMR spectra, FT-IR spectra, and HR-MS, respectively. The as-synthesized MABet was then used as polymerizable comonomer to partially or completely substitute Bis-GMA in a 50:50 Bis-GMA: TEGDMA resin (5B5T) to formulate dental restorative resins. These were then determined for the viscosity behavior, light transmittance, real-time degree of conversion, residual monomers, mechanical performance, cytotoxicity, and antibacterial activity against Streptococcus mutans (S. mutans) in detail. ResultsAmong all experimental resins, increasing the MABet concentration to 50 wt% made the resultant 5MABet5T resin have a maximum in viscosity and appear dark yellowish after polymerization. In contrast, the 1MABet4B5T resin with 10 wt% MABet possessed comparable shear viscosity and polymerization conversion (46.6 ± 1.0% in 60 s), higher flexural and compressive strength (89.7 ± 7.8 MPa; 345.5 ± 14.4 MPa) to those of the 5B5T control (48.5 ± 0.6%; 65.7 ± 6.7 MPa; 223.8 ± 57.1 MPa). This optimal resin also had significantly lower S. mutans colony counts (0.35 ×108 CFU/mL) than 5B5T (7.6 ×108 CFU/mL) without affecting cytocompatibility. SignificanceIntroducing plant-derived polymerizable MABet monomer into dental restorative resins is an effective strategy for producing antibacterial dental materials with superior physicochemical property.

Impact of bisphenol A and analogues eluted from resin-based dental materials on cellular and molecular processes: An insight on underlying toxicity mechanisms.

Dental resin systems, used for artificial replacement of teeth and their surrounding structures, have gained popularity due to the Food and Drug Administration's (FDA) recommendation to reduce dental amalgam use in high-risk populations and medical circumstances. Bisphenol A (BPA), an endocrine-disrupting chemical, is an essential monomer within dental resin in the form of various analogues and derivatives. Leaching of monomers from resins results in toxicity, affecting hormone metabolism and causing long-term health risks. Understanding cellular-level toxicity profiles of bisphenol derivatives is crucial for conducting toxicity studies in in vivo models. This review provides insights into the unique expression patterns of BPA and its analogues among different cell types and their underlying toxicity mechanisms. Lack of a consistent cell line for toxic effects necessitates exploring various cell lines. Among the individual monomers, BisGMA was found to be the most toxic; however, BisDMA and BADGE generates BPA endogenously and found to elicit severe adverse reactions. In correlating in vitro data with in vivo findings, further research is necessary to classify the elutes as human carcinogens or xenoestrogens. Though the basic mechanisms underlying toxicity were believed to be the production of intracellular reactive oxygen species and a corresponding decline in glutathione levels, several underlying mechanisms were identified to stimulate cellular responses at low concentrations. The review calls for further research to assess the synergistic interactions of co-monomers and other components in dental resins. The review emphasizes the clinical relevance of these findings, highlighting the necessity for safer dental materials and underscoring the potential health risks associated with current dental resin systems.

Construction of dentin-on-a-chip based on microfluidic technology and tissue engineering

AimThree-dimensional (3D) cell culture systems perform better in resembling tissue or organism structures compared with traditional 2D models. Organs-on-chips (OoCs) are becoming more efficient 3D models. This study aimed to create a novel simplified dentin-on-a-chip using microfluidic chip technology and tissue engineering for screening dental materials. MethodologyA microfluidic device with three channels was designed for creating 3D dental tissue constructs using stem cells from the apical papilla (SCAP) and gelatin methacrylate (GelMA). The study investigated the effect of varying cell densities and GelMA concentrations on the layer features formed within the microfluidic chip. Cell viability and distribution were evaluated through live/dead staining and nuclei/F-actin staining. The osteo/odontogenic potential was assessed through ALP staining and Alizarin red staining. The impact of GelMA concentrations (5 %, 10 %) on the osteo/odontogenic differentiation trajectory of SCAP was also studied. ResultsThe 3D tissue constructs maintained high viability and favorable spreading within the microfluidic chip for 3–7 days. A cell seeding density of 2 × 104 cells/μL was found to be the most optimal choice, ensuring favorable cell proliferation and even distribution. GelMA concentrations of 5 % and 10 % proved to be most effective for promoting cell growth and uniform distribution. Within the 5 % GelMA group, SCAP demonstrated higher osteo/odontogenic differentiation than that in the 10 % GelMA group. ConclusionIn 3D culture, GelMA concentration was found to regulate the osteo/odontogenic differentiation of SCAP. The study recommends a seeding density of 2 × 104 cells/μL of SCAP within 5 % GelMA for constructing simplified dentin-on-a-chip. Clinical SignificanceThis study built up the 3D culture protocol, and induced odontogenic differentiation of SCAP, thus forming the simplified dentin-on-a-chip and paving the way to be used as a well-defined biological model for regenerative endodontics. It may serve as a potential testing platform for cell differentiation.

Evaluation of early bacterial adhesion on CAD/CAM dental materials: an in situ study.

The aim of this research was to determine if there are differences in early bacterial adhesion among CAD/CAM dental materials after 24h exposure in the oral environment. One hundred twenty specimens were prepared according to the manufacturer's recommendations and divided into six groups: RBC (resin-based composite), PMMA (polymethyl methacrylate), PEEK (polyether ether ketone), ZP (zirconia polished), ZG (zirconia glazed), and cobalt-chromium alloy (CoCr alloy). Twenty healthy participants were instructed to carry an intraoral device with six specimens, one per group, for 24h. Thereafter, real-time polymerase chain reaction (qPCR) and scanning electron microscopy (SEM) analyses enabled quantification and 2D view of biofilm formed on the specimens' surfaces. Kruskal-Wallis test and Dunn's post hoc analysis were used for inter-group comparison and data were presented as median (minimum-maximum). RBC specimens accumulated less bacteria, in comparison with ZG (p = 0.017) and PEEK specimens (p = 0.030), that dominated with the highest amount of adhered bacterial biofilm. PMMA, CoCr, and ZP specimens adhered more bacteria than RBC (p > 0.05), and less than ZG (p > 0.05) and PEEK (p > 0.05). The bacterial number varied considerably among participants. The obtained results enable a closer view into the susceptibility of CAD/CAM materials to microorganisms during the presence in the oral environment, which can be beneficial for a proper selection of these materials for a variety of dental restorations.

Effect of beverages, denture cleanser and chlorhexidine gluconate on surface roughness of flexible denture base material: an in vitro study.

The purpose of the study was to evaluate and compare the effect of beverages, denture cleanser and chlorhexidine gluconate solution on surface roughness of flexible denture base material. Fifty flexible denture base resin specimens measuring 50±1mm in diameter and 0.5±0.05 mm in thickness were fabricated. The specimens were divided into five groups each containing ten specimens. The specimens were immersed in distilled water (Control group A); hot coffee (Group B); cold beverage (Group C); sodium perborate containing denture cleanser (Group D) and 2% chlorhexidine gluconate solution (Group E). The specimens were immersed for 10 min daily in mentioned solutions for up to 60 days. Surface roughness (Ra) was evaluated on the 1st, 20th and 60th day with the help of atomic force microscope. The statistical analysis was done using two-way ANOVA and Tukey's Post hoc test. The two- way ANOVA revealed that the average Ra values varied significantly depending on the type of solution used for immersion (p<0.001) and the duration of immersion (p<0.001). Variation in surface roughness with cold beverage was highest (p=0.001). On the 60th day the surface roughness of flexible denture base resin material was higher with cold beverage (0.184 μm) and denture cleanser (0.203 μm) than that of distilled water (0.052 μm) hot coffee (0.030 μm) and 2% chlorhexidine gluconate (0.068 μm). Exposure to cold beverage, which was acidic in nature and peroxide containing denture cleanser, produces much rougher surface in the thermoplastic polyamide flexible denture base resin specimens.

Bioactive ceramic-based materials: beneficial properties and potential applications in dental repair and regeneration.

Bioactive ceramics, primarily consisting of bioactive glasses, glass-ceramics, calcium orthophosphate ceramics, calcium silicate ceramics and calcium carbonate ceramics, have received great attention in the past decades given their biocompatible nature and excellent bioactivity in stimulating cell proliferation, differentiation and tissue regeneration. Recent studies have tried to combine bioactive ceramics with bioactive ions, polymers, bioactive proteins and other chemicals to improve their mechanical and biological properties, thus rendering them more valid in tissue engineering scaffolds. This review presents the beneficial properties and potential applications of bioactive ceramic-based materials in dentistry, particularly in the repair and regeneration of dental hard tissue, pulp-dentin complex, periodontal tissue and bone tissue. Moreover, greater insights into the mechanisms of bioactive ceramics and the development of ceramic-based materials are provided.

МАТЕМАТИЧЕСКОЕ МОДЕЛИРОВАНИЕ РАСПРЕДЕЛЕНИЯ НАПРЯЖЕНИЙ В СТЕНКАХ КОНУСНЫХ ИМПЛАНТАТОВ ИЗ СПЛАВА ВТ6

Today, an interdisciplinary approach to solving the problems of implantology is the key to the effective use of intraosseous dental implants. The possibilities of preclinical modeling of the state of bone tissue and the future implantation and prosthetic beds allow us to assess the possible risks of implant rejection, calculate the necessary tightening force of screws in implantation systems and predict the points of application and stress distribution of dental implantation materials, taking into account the latter, the desire to improve modeling will allow us to obtain a predictable treatment result. In this study, a mathematical model of the stress distribution on the walls of a conical implant was investigated, taking into account the physical properties of the VT 6 material, an assessment was carried out using the example of computer models with embedded alloy characteristics, and the Mises distribution indicators were calculated. It is worth noting that the VT6 alloy has a very high quality, thanks to alloying additives. This titanium alloy includes aluminum, which has a beneficial effect on the strength of implants, as well as vanadium, which can increase the strength of the metal and make it more ductile. Titanium alloy VT6 has characteristics that are comparable to those of stainless steel, due to which it is considered as an inert metal for use in the oral cavity. The novelty of the proposed model lies in the fact that it operates with the minimum possible set of input data and provides adequate estimates of the most significant output parameters that are necessary for practical application. The obtained analytical results are illustrated by examples of calculating equivalent stresses in implants and peri-implant tissue for real structures of the future orthopedic prosthesis.

Comparison of Blue and Infrared Light Transmission Through Dental Tissues and Restorative Materials.

The depth of cure using blue-light photocuring units (BL) is limited by tooth structure and qualities of the restorative material through which the activating wavelength must pass. Recent developments incorporate an infrared (IR) activated upconversion (UC) fluorescence of a lining agent filled with nanocrystals of NaYF4 and doped with YB+3 and Tm+3 that emit both blue and violet light locally at the interface of the liner and restorative resin. The purpose of this study was to evaluate the BL and 975 nm infrared (IR) light power transmission through dental tissues and restorative materials. Power transmissions of the IR laser (975 nm) and a monowave blue-only light-curing unit (Bluephase 16i) through dental tissues (enamel, dentin, and enamel/dentin junction, or DEJ), eight (8) various dental resin composites, and eight (8) dental ceramics, each at four thicknesses (1, 2, 3 and 4 mm) were evaluated (n=5) using a thermopile sensor (PM10, Coherent Inc) connected to a laser power meter (Fieldmate, Coherent Inc). Power transmission values of each light source and restorative material were subjected to analysis of variance and Tukey test at a pre-set alpha of 0.05. A linear correlation (r=0.9884) between the supplied current and emitted IR power of the laser diode was found, showing no statistical power reduction with increased distances (collimated beam). For tooth tissues, the highest power transmissions for both light sources were observed using 1.0 mm enamel while the lowest values were found for 2.0 mm dentin and an association of 2.0 mm DEJ and 1.0 mm dentin. The only group where IR demonstrated significantly higher transmission when compared to BL was 1.0 mm enamel. For all resin composites and dental ceramics, increased thickness resulted in a reduction of IR power transmission (except for EverX Posterior fiber-reinforced composite and e.max HT ceramic). IR resulted in higher transmission through all resin composites, except for Tetric EvoCeram White. The highest BL transmission was observed for SDR Flow, at all thicknesses. Higher IR/BL ratios were observed for EverX Posterior, Herculite Ultra, and Lava Ultimate, while the lowest ratio was observed for Tetric EvoCeram White. Reduced translucency shades within the same material resulted in lower power ratio values, especially for BL transmission. Higher IR/BL ratios were observed for e.Max LT, VitaVM7 Base Dentin, and e.max CAD HT, while the lowest values were found for VitaVM7 Enamel and Paradigm C. IR power transmission through enamel was higher when compared to blue light, while no difference was observed for dentin. The power transmission of IR was higher than BL for resin composites, except for a high value and low chroma shade. Fiber-reinforced resin composite demonstrated the highest IR/BL power transmission ratio. A greater IR/BL ratio was observed for lower translucency ceramics when compared to high translucency.

Titanium- and Strontium-Infused Calcium Silicates Toward Restorative and Regenerative Purposes.

Dental materials with dentine regenerative properties are preferred over conventional materials. Calcium silicate cements, such as Biodentine, are bioactive and offer excellent sealing ability, making them ideal for various dental treatments. This study aimed to fabricate bioactive calcium silicates infused with titanium (Ti) and strontium (Sr) to optimize their neo-angiogenic, antimicrobial, and regenerative propertieswhile maintaining mechanical stability. Ti- and Sr-infused calcium silicate cements were synthesized, and their mineral phases were characterized using X-ray diffraction. Morphological and elemental analyses were performed using field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDS). Raman spectroscopy was used to confirm the formation of bioactive material. A hemocompatibility assessment was conducted to evaluate blood compatibility. The presence of Ca2, SiO4, and SrTiO3 mineral phases indicated the successful infusion of Ti and Sr into the calcium silicate cement. FESEM and EDS revealed interconnected small spheres and rods in the silicate network with the relevant elemental compositions. Raman spectra verified that Si-O-Si and Ti-O-Ti vibrations exist, validating the formation of a bioactive material. The hemocompatibility assessment demonstrated optimal blood compatibility. This study successfully fabricated an improved calcium silicate-based material with enhanced regenerative properties and excellent biocompatibility. This newly formed substrate holds promise for providing superior restorative solutions and aiding in conservative treatment modalities during dental procedures.

Investigation of zinc polycarboxylate cement used in dental treatments in terms of retrospective dosimeter.

Zinc polycarboxylate cement is one of the few dental materials that demonstrate true adhesion to tooth structure. It is suitable for use in living organisms without causing harm. Its strong adhesion to teeth and low level of irritancy are two important parameters for the dental applications. In this study, the dosimetry properties of zinc polycarboxylate cement using thermoluminescence (TL) method were investigated and determined the effectiveness of its use as a good dosimeter. According to the results of this study, the sample shows a good TL properties with three main peaks found around 140°C, 220°C and 330°C. It has a wide linear dose response between 72 Gy and 2.3kGy and good reusability of the TL peak found at 330°C. Unfortunately, the TL peak intensity values are rapidly faded within a short waiting time interval. Zinc polycarboxylate cement, which is frequently used in dental crowns, can be used as a retrospective dosimeter for measuring the amount of radiation in space studies and nuclear accidents due to its wide linear dose-response curve in the high dose region.

Biomechanics, Bioactive and Biomimetic philosophy in restorative dentistry ̶ Quo vadis?

IntroductionIn recent years, restorative dentistry has embraced various techniques, including direct, semi-direct, and indirect restorations, to address the replacement of lost tooth tissue. The focus has been on integrating the principles of Biomechanics, Bioactivity, and Biomimicry (3-Bio) as key drivers behind these innovations. MethodsThe aim of this article is to provide a concise overview of three important aspects of restorative dental materials: biomechanics, bioactivity and biomimetics. Further, the aim is to provide readers with relevant information on the 3-Bio concept, offering insights in to the innovative approaches shaping modern restorative dentistry. ResultsDeveloping restorative materials with interactive properties aligned with the 3-Bio concept poses a significant challenge. Currently, dentistry lacks a comprehensive system in this regard. The development of dental materials based on the 3-Bio concept could potentially elicit positive mechanical and biological responses in targeted tooth tissues. ConclusionAssessing several parameters through a battery of in vitro and in silico assays could help in tailoring the different aspects of the 3-Bio concept, spanning from bioactivity to biomimetics via biomechanics. This approach could allow the prediction and translation of the clinical performance of the assessed restorative materials. Clinical significanceThe findings of this opinion article highlight that the development of restorative materials aligned with the 3-Bio concept could enhance the management of dental defects and extend the longevity of bonded restorations, thereby improving patient care through tissue preservation. More collective efforts between clinicians, researchers, and even industrial partners are required to fully understand the correlation between bioactive behavior, biomechanical limitations, and biomimetics to provide suitable restorative materials for specific clinical applications.

Engineering antibacterial tannic acid/polyethyleneimine coatings on lithium disilicate glass-ceramics for dental applications

This study introduces an innovative approach to enhance the antibacterial properties of lithium disilicate glass ceramics, widely used in dental restorations. We explored the efficacy of tannic acid (TA) and polyethyleneimine (PEI) as coating agents, capitalizing on a robust defense against microbial colonization and biofilm formation. We employed various analytical techniques, including differential thermal analysis (DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), to characterize the physical, chemical, and antibacterial properties of the TA/PEI coated glass-ceramics. Results indicated a notable improvement in the mechanical properties, such as Weibull modulus, elastic modulus, and fracture toughness of the coated samples. Moreover, the TA/PEI coatings displayed superior thermal stability and effective leaching behavior in different pH, pertinent to dental applications. Significantly, the TA/PEI coatings exhibited high antibacterial activity against Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria, making them promising candidates for enhancing the bioactivity of dental restorative materials. This study lays the foundation for developing advanced antibacterial coatings for dental applications, aiming to improve patient outcomes in dental care.

Restoration of Root-filled Teeth: A Literature Review

Abstract The continued evolution of dental materials and techniques, combined with a trend towards more conservative endodontic-restorative procedures, prompts re-evaluation of the scientific literature. The aim of this literature review was to provide an updated overview of the existing clinical literature relating to the restoration of root filled teeth.

The Revival of Essay-Type Questions in Medical Education: Harnessing Artificial Intelligence and Machine Learning.

To analyse and compare the assessment and grading of human-written and machine-written formative essays. Quasi-experimental, qualitative cross-sectional study. Place and Duration of the Study: Department of Science of Dental Materials, Hamdard College of Medicine & Dentistry, Hamdard University, Karachi, from February to April 2023. Ten short formative essays of final-year dental students were manually assessed and graded. These essays were then graded using ChatGPT version 3.5. The chatbot responses and prompts were recorded and matched with manually graded essays. Qualitative analysis of the chatbot responses was then performed. Four different prompts were given to the artificial intelligence (AI) driven platform of ChatGPT to grade the summative essays. These were the chatbot's initial responses without grading, the chatbot's response to grading against criteria, the chatbot's response to criteria-wise grading, and the chatbot's response to questions for the difference in grading. Based on the results, four innovative ways of using AI and machine learning (ML) have been proposed for medical educators: Automated grading, content analysis, plagiarism detection, and formative assessment. ChatGPT provided a comprehensive report with feedback on writing skills, as opposed to manual grading of essays. The chatbot's responses were fascinating and thought-provoking. AI and ML technologies can potentially supplement human grading in the assessment of essays. Medical educators need to embrace AI and ML technology to enhance the standards and quality of medical education, particularly when assessing long and short essay-type questions. Further empirical research and evaluation are needed to confirm their effectiveness. Machine learning, Artificial intelligence, Essays, ChatGPT, Formative assessment.

The Contribution of Scanning Force Microscopy on Dental Research: A Narrative Review.

Scanning force microscopy (SFM) is one of the most widely used techniques in biomaterials research. In addition to imaging the materials of interest, SFM enables the mapping of mechanical properties and biological responses with sub-nanometer resolution and piconewton sensitivity. This review aims to give an overview of using the scanning force microscope (SFM) for investigations on dental materials. In particular, SFM-derived methods such as force-distance curves (scanning force spectroscopy), lateral force spectroscopy, and applications of the FluidFM® will be presented. In addition to the properties of dental materials, this paper reports the development of the pellicle by the interaction of biopolymers such as proteins and polysaccharides, as well as the interaction of bacteria with dental materials.

Influence of Immediate Dentin Sealing on Bond Strength of Resin-Based CAD/CAM Restoratives to Dentin: A Systematic Review of In Vitro Studies.

Immediate dentin sealing (IDS) is a method of improving the bond strength of indirect dental restorative materials to dentin and belongs to the biomimetic protocols of contemporary dentistry. The purpose of this systematic review was to evaluate the effect of IDS on the bond strength of resin-based CAD/CAM materials to dentin. PubMed and MEDLINE, Scopus, and the Web of Science were searched by two individual researchers, namely for studies that have been published in English between 1 January 2005 and 31 December 2023 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The inclusion criteria encompassed articles related to in vitro studies, measuring the bond strength through microtensile bond strength (μ-TBS), micro-shear bond strength (μ-SBS), tensile bond strength (TBS) or shear bond strength (SBS) tests after the use of the IDS technique. The included restorative materials comprised resin-based CAD/CAM materials bonded to dentin. A total of 1821 studies were identified, of which 7 met the inclusion criteria. A meta-analysis was not deemed appropriate due to the high level of diversity inthe publications and techniques. The use of IDS yielded higher bond strength outcomesin various experimental conditions and resin-based CAD/CAM materials. Overall, IDS in CAD/CAM restorations may contribute to better clinical outcomesand improved restoration longevity due to this property.

Bond Integrity and Microleakage of Orthodontic Bands Cemented by Glass Ionomer Cements Stored in Static Magnetic Field

Aim: Improving the band-tooth bond integrity by glass ionomer cement (GIC) is essential in orthodontic treatments. As, microleakage under bands induced enamel demineralization. Storing the dental material to updated magnets improved their mechanical properties. This research aimed to assess the microleakage of GIC after storing in a static magnetic field (SMF). Material and Methods: Forty premolars and their suitable bands were randomly classified into two main groups according to the types of GIC tested in this research; resin-modified GIC (RMGIC) and conventional GIC (CGIC). Each group was subdivided according to the exposure to SMF before polymerization into two subgroups. CGIC not exposed to SMF (CC), CGIC exposed to SMF (CM), RMGIC not exposed to SMF (LC) and RMGIC exposed to SMF (LM). SMF intensity performed was 0.225 Tesla, exposed for 48 hours at room temperature. The entire tube of RMGIC was inserted in SMF, where the powder of CGIC was stored in SMF. The microleakage under the band was evaluated under a 20× stereomicroscope by dye penetration technique at the cement band interface. Wilcoxon signed-rank test was used for data analysis, p ≤ .05. Results: The main (SD) microleakage of GIC reduced significantly ( p = .043) after being exposed to SMF from 3.1950 (0.632) mm to 1.7095 (0.1176) mm and from 0.8745 (0.1104) mm to 0.6430(0.094) mm for CGIC and RMGIC, respectively. Conclusion: Storing the CGIC powder in (0.225 T) SMF improves band-tooth bond integrity. Additionally, the preservation of RMGIC in SMF minimized the microleakage under orthodontic bands.

Challenges of Dental Material' Ordering at Governmental PHC clinics, Specialized Dental Centers, and Hospitals in KSA; Observational study

Background: Ordering of dental materials (DM) at Ministry of Health (MOH) dental facilities is restricted by many challenges in time and supply among other factors Methods: a questionnaire was distributed among dentists working at MOH dental facilities exploring the ordering way of DM and challenges if exist. Result: 53.8% of dentists still use paper slip for ordering DM. Shortage is still a major obstacle as cited by 59.8% and it may take up to two weeks to receive the ordered DM Conclusion: Atomization of DM ordering will save effort and time and enact efficient utilization of DM and reduce waste in expired or discarded materials.

Community social responsibility of continued and appropriate use of silver amalgam as dental restorative material in southern India: A cross-sectional study

Background For more than 150 years, dental amalgam (DA) has been popular as a dental restorative material. Many organizations oppose its use due to perceived toxicity and environmental concerns. Hence, this study aimed to explore the continued use of DA from a South Indian dental practitioners’ perspective. Methods This cross-sectional study was conducted among fifty-two private and public dental practitioners of Udupi district in Southern India. A self‑administered questionnaire was distributed, that involved assessment of their preferences, continuation of use and concerns of using DA as a restorative material. The percentage contribution of each variable was calculated. Preferences for continuation of use of silver amalgam based upon the age, experience and mercury toxicity as a risk factor were analyzed using Students-t test and Chi-square test. Results Most dentists were satisfied (87%) with the results of the DA, found minimal failures (96%) and found DA more economical (89%). More than half (54%) of the participants reported that they would not continue the use of DA owing to mercury toxicity and environmental concerns. Dentists with higher age and longer clinical experience preferred continuation of DA. Conclusions Despite satisfaction with DA for its minimal failure, longevity and affordability, the authors found that most practitioners did not prefer its continued usage. This highlights their concerns over mercury toxicity and soft tissue lesions and accentuates their community social responsibility. There is also an urgent need to educate dentists on mercury hygiene, mercury waste management and disposal.

The Impact of Repeated Steam Sterilization Cycles on the Efficacy of Chairside Adjustment Kits for Polishing Monolithic Multi-Layered Zirconia Dental Restoration Material.

BACKGROUND Before insertion, chairside adjustment kits are heat sterilized for positioning and polishing dental restorations. This study aimed to evaluate the effects of 2 steam sterilization cycles on the efficacy of polishing highly translucent monolithic zirconia (HTMLZ) dental restoration material. MATERIAL AND METHODS 100 HTMLZ disc-shaped specimens were adjusted (grinding, finishing, polishing) with EVE Diacera kit. Two steam sterilization techniques [standard (Gp S), immediate/flash (Gp (F)] of CAK were further subgrouped based on number of sterilization cycles [cycle 1 (control), cycle 5, 10, 15, and 20 (experimental)] (n=10 each). Each subgroup accordingly was evaluated for average surface roughness (Ra) and root mean square roughness (Rq) using a profilometer. Mean and standard deviation of 5 subgroups were statistically analyzed using one-way ANOVA/post hoc Tukey's test. Scanning electron microscopy complemented Ra, Rq measurements. Statistical differences of P≤0.05 were considered significant. RESULTS HTMLZ specimens in both groups showed increased (Ra/Rq) values after repeated sterilization of EVE Diacera kit, with Gp F showing lesser increase than Gp S (20 cycles). Gp F at 10 cycles and Gp S at 15 cycles showed clinically unacceptable roughness threshold (0.25 μm). Differences between subgroups for Ra and Rq values were significant (P≤0.05) with less differences within groups observed in early cycles (1, 10). Results validate the manufacturer's recommendations of using flash sterilization/10 cycles for EVE Diacera kit. CONCLUSIONS Repeated sterilization reduces efficacy of chairside adjustment kit to produce smooth surfaces on HTMLZ. This study recommends flash sterilization to a maximum of 10 times to get the clinically acceptable results of Ra and Rq.