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Clinical Oral Investigations Nov 2022To evaluate the wear resistance and abrasiveness of monolithic CAD/CAM ceramics.
OBJECTIVES
To evaluate the wear resistance and abrasiveness of monolithic CAD/CAM ceramics.
MATERIALS AND METHODS
Rectangular-shaped specimens (12 mm × 6.5 mm × 1.5 mm) were sectioned from the following CAD/CAM blocks (n = 10); partially crystallized lithium disilicate (PLD), experimental fully crystallized lithium disilicate (FLD), zirconia-reinforced lithium silicate (ZLS), super-translucent monolithic zirconia (SMZ), and ultra-translucent monolithic zirconia (UMZ). Silicon carbide papers were used to mechanically flatten and polish the surfaces. PLD specimens were subjected to a combined crystallization/glazing firing cycle. Ceramic specimens were mounted to the wear device and tested for 200,000 cycles against human premolars at 20 N force and 2 mm sliding distance. Artificial saliva was used as a lubricant. The teeth were scanned using micro-CT before and after the wear test and the generated models were overlapped to determine the volumetric tooth loss. Before and after the test, specimens' weights and surface roughness (R) values were measured, and the differences were calculated. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) were utilized for microstructural and chemical analysis. Statistical analysis was performed using one-way ANOVA or an equivalent test for non-parametric results. Significance level was set at P ≤ 0.05.
RESULTS
The type of ceramic material affected the ceramic and antagonist wear rates (P < 0.001). PLD and ZLS had the highest ceramic and antagonist wear, whereas UMZ and SMZ demonstrated the lowest wear values. The FLD group showed comparable antagonist wear and significantly less ceramic wear than PLD and ZLS.
CONCLUSIONS
Monolithic zirconia demonstrated the best wear resistance and least abrasiveness to the antagonist. The experimental lithium disilicate was more wear-resistant than other glass-ceramic groups.
CLINICAL RELEVANCE
Monolithic zirconia is wear-resistant and gentle on the antagonist. In contrast, glass-ceramics are more abrasive to enamel.
Topics: Humans; Mastication; Materials Testing; Surface Properties; Dental Porcelain; Zirconium; Ceramics; Computer-Aided Design
PubMed: 35819543
DOI: 10.1007/s00784-022-04611-w -
Pharmaceutics Oct 2021Eye injuries due to corneal abrasions, chemical spills, penetrating wounds, and microbial infections cause corneal scarring and opacification that result in impaired...
Eye injuries due to corneal abrasions, chemical spills, penetrating wounds, and microbial infections cause corneal scarring and opacification that result in impaired vision or blindness. However, presently available eye drop formulations of anti-inflammatory and antibiotic drugs are not effective due to their rapid clearance from the ocular surface or due to drug-related side effects such as cataract formation or increased intraocular pressure. In this article, we presented the development of a dextran sulfate-based polymer wafer (DS-wafer) for the effective modulation of inflammation and fibrosis and demonstrated its efficacy in two corneal injury models: corneal abrasion mouse model and alkali induced ocular burn mouse model. The DS-wafers were fabricated by the electrospinning method. We assessed the efficacy of the DS-wafer by light microscopy, qPCR, confocal fluorescence imaging, and histopathological analysis. These studies demonstrated that the DS-wafer treatment is significantly effective in modulating corneal inflammation and fibrosis and inhibited corneal scarring and opacification compared to the unsulfated dextran-wafer treated and untreated corneas. Furthermore, these studies have demonstrated the efficacy of dextran sulfate as an anti-inflammatory and antifibrotic polymer therapeutic.
PubMed: 34683921
DOI: 10.3390/pharmaceutics13101628 -
Brazilian Dental Journal 2022The objective of this study was to evaluate the effect of natural bleaching products on the color, whiteness, and superficial properties of dental enamel. Seventy...
The objective of this study was to evaluate the effect of natural bleaching products on the color, whiteness, and superficial properties of dental enamel. Seventy fragments of bovine teeth were obtained (6mm x 6mm x 2mm). Initial surface roughness (Surfcorder SE1700, Kosakalab), microhardness (HMV-2, Shimadzu), color (EasyShade, VITA), and surface gloss (Micro-Gloss 45º BYK, Gardner) readings were done. Samples were separated into five groups (n=14) according to the treatments used: CT-conventional toothpaste (negative control); CH-charcoal; TU-turmeric; BP-banana peel, and CP16%-16% carbamide peroxide gel (positive control, 4 h/day for 14 days), and then brushed for 560 cycles (T1) and 1200 cycles (T2), equivalent to 14 and 30 days of brushing. New measurements were performed after T1 and T2. The whiteness index for dentistry change (∆WID) and Weight loss (Wl) were calculated. CP16% demonstrated the highest (p<.05) color change (ΔE00) and ∆WID (2-way ANOVA, Bonferroni, p<.05). Surface gloss alterations were lower for TU, CP16%, and BP. CT and CH increased surface roughness (p<.05). CP16% decreased enamel microhardness. CH presented medium abrasiveness, and CT and TU, low abrasiveness. The popular bleaching products were not efficient for tooth whitening. Furthermore, brushing with charcoal increased the enamel surface roughness, and CP16% decreased enamel microhardness over time.
Topics: Animals; Biological Products; Cattle; Charcoal; Dental Enamel; Tooth Bleaching; Tooth Bleaching Agents
PubMed: 35766717
DOI: 10.1590/0103-6440202204863 -
Journal of Esthetic and Restorative... Jun 2020The aim of this study was to evaluate and compare surface roughness, gloss, and color change of dental enamel after being brushed with toothpastes containing diamond...
OBJECTIVE
The aim of this study was to evaluate and compare surface roughness, gloss, and color change of dental enamel after being brushed with toothpastes containing diamond powder and traditional abrasives.
MATERIALS AND METHODS
Seventy enamel slabs were derived from 70 bovine incisors. The slabs were brushed with six different toothpastes and artificial saliva as a negative control. The specimens were then stained with black tea mixed with citric acid (3 days, pH = 4) and again brushed with the same toothpastes. R (contact profilometer), gloss (glossmeter), and color (CIE L* a* b* system) values were measured after each step.
RESULTS
Emoform-F Diamond (contains diamond powder and traditional abrasives) offered significantly the best improvement of R and gloss values after the first brushing sequence and the best recovery of the brightness of enamel after staining and second brushing sequence (P < .05). AMC 2.5 (contains only diamond powder as abrasive) was not able to offer such improvement.
CONCLUSION
Diamond powder as an additional abrasive in toothpastes could be able to offer a further improvement of R , gloss, and color values of enamel.
Topics: Animals; Cattle; Color; Dental Enamel; Diamond; Surface Properties; Toothbrushing; Toothpastes
PubMed: 32277866
DOI: 10.1111/jerd.12588 -
International Dental Journal Dec 2013A number of factors should be taken into account when designing toothpaste formulations for use by children at the different stages of their development. While adult... (Review)
Review
A number of factors should be taken into account when designing toothpaste formulations for use by children at the different stages of their development. While adult toothpaste formulations may provide caries prevention benefits for children at risk of caries, these formulations may also contain higher levels of abrasive in order to address the staining needs of the adult population owing to smoking and the consumption of dietary chromogens such as coffee and tea, which are not normally found in the diet of children. While toothpastes formulated for adults are also likely to contain higher concentrations of surfactant and flavour, many children prefer toothpastes with mild flavours and modest foaming characteristics. An ideal children's toothpaste formulation should therefore aim to maximise fluoride availability, with appropriate abrasivity, while still delivering effective cleaning, as well as levels and types of flavour and surfactant to provide an acceptable brushing experience. Selection of toothpaste flavour types for children of different ages should ideally be based directly upon preference data from children. Flavours perceived as pleasant during brushing studies have been linked to increased brushing time, which, in turn, can increase the delivery and efficacy of fluoride from toothpastes. Therefore, manufacturers select tested, child-friendly flavours to maximise compliance, providing a more pleasurable brushing experience and oral health benefits.
Topics: Biological Availability; Cariostatic Agents; Chemistry, Pharmaceutical; Child; Flavoring Agents; Fluorides; Humans; Surface-Active Agents; Toothpastes
PubMed: 24283285
DOI: 10.1111/idj.12083 -
European Journal of Dentistry 2017Oscillating diamond instruments are considered gentle sources for the removal of demineralized tooth hard tissues and the preparation of cavity angles and margins needed... (Review)
Review
Oscillating diamond instruments are considered gentle sources for the removal of demineralized tooth hard tissues and the preparation of cavity angles and margins needed in minimally invasive dentistry. However, there is a question if literature provides enough evidence for their efficacy in restorative dentistry procedures. A literature search until May 2016 was conducted, using PubMed, Scopus, and The Cochrane Central Register of Controlled Trials databases. The quality of the studies was assessed using the recommendation of the Oxford Centre for Evidence-based Medicine. Fifty-five studies were finally included in the study. Of which, 78.2% of them were laboratory studies and only 21.8% were clinical studies. The strength of recommendation was 5 for most of them and D their grade of evidence. Bond strength of adhesives on surfaces prepared with these instruments, effective caries removal and cutting characteristics of the oscillating instruments were the main targets of the studies. Conventional diamond, steel, and chemical vapor deposition diamond tips and systems based on abrasive slurry were the oscillating tips, used in different studies. The strength of recommendation and grade of evidence of the studies were low. Although these devices seem to be useful for many clinical situations, there is a need for more well-structured evidence-based studies with more widely accepted procedures and common devices, to have more meaningful results and conclusions of higher strength.
PubMed: 28729806
DOI: 10.4103/ejd.ejd_232_16 -
Journal (Canadian Dental Association) Sep 1998Dental porcelain has found an increased number of applications in recent years with the development of new methods for the construction of porcelain veneers and... (Review)
Review
BACKGROUND
Dental porcelain has found an increased number of applications in recent years with the development of new methods for the construction of porcelain veneers and intracoronal restorations. In addition, it is used in metal-ceramic and all-porcelain crowns and bridges for the restoration of anterior and posterior teeth.
METHODS
This paper presents a review of a number of studies that have examined the visual and microscopic appearance and roughness of glazed, unglazed and polished porcelain surfaces using techniques such as, scanning electron microscopy and surface profilometry.
FINDINGS
All have agreed that glazed porcelain provides a smooth and dense surface. Many have shown that polishing can produce an equally smooth surface, which may even be esthetically better. Some studies supported the use of polishing as an alternative to glazing. However, reports have shown that unglazed porcelain is more abrasive than glazed.
CLINICAL SIGNIFICANCE
This paper aims to guide general practitioners in the proper polishing of adjusted porcelain in the dental office. The recommendations of various authors are summarized in Table I.
Topics: Crowns; Dental Polishing; Dental Porcelain; Dental Veneers; Denture, Partial; Esthetics, Dental; Hot Temperature; Humans; Inlays; Metal Ceramic Alloys; Microscopy, Electron, Scanning; Surface Properties; Tooth Abrasion
PubMed: 9785688
DOI: No ID Found -
Journal of the Royal Society, Interface Jul 2016Different diets wear teeth in different ways and generate distinguishable wear and microwear patterns that have long been the basis of palaeodiet reconstructions. Little...
Different diets wear teeth in different ways and generate distinguishable wear and microwear patterns that have long been the basis of palaeodiet reconstructions. Little experimental research has been performed to study them together. Here, we show that an artificial mechanical masticator, a chewing machine, occluding real horse teeth in continuous simulated chewing (of 100 000 chewing cycles) is capable of replicating microscopic wear features and gross wear on teeth that resemble wear in specimens collected from nature. Simulating pure attrition (chewing without food) and four plant material diets of different abrasives content (at n = 5 tooth pairs per group), we detected differences in microscopic wear features by stereomicroscopy of the chewing surface in the number and quality of pits and scratches that were not always as expected. Using computed tomography scanning in one tooth per diet, absolute wear was quantified as the mean height change after the simulated chewing. Absolute wear increased with diet abrasiveness, originating from phytoliths and grit. In combination, our findings highlight that differences in actual dental tissue loss can occur at similar microwear patterns, cautioning against a direct transformation of microwear results into predictions about diet or tooth wear rate.
Topics: Animals; Horses; Mastication; Models, Biological; Molar; Tooth Wear
PubMed: 27411727
DOI: 10.1098/rsif.2016.0399 -
Journal of Indian Society of... 2021Adequate plaque control facilitates good gingival and periodontal health, prevents tooth decay, and preserves oral health. Toothbrushing is the primary method of...
A profilometric and scanning electron microscopic analysis of tooth surface abrasion caused by rotary/oscillatory, linear motion, sonic, and ultrasonic toothbrushes: An study.
BACKGROUND
Adequate plaque control facilitates good gingival and periodontal health, prevents tooth decay, and preserves oral health. Toothbrushing is the primary method of removing plaque and can be classified into powered and manual toothbrushes.
AIM
The primary objective was to compare the abrasiveness and surface roughness caused by four different power-driven toothbrushes with a different mode of action, on tooth surfaces .
MATERIALS AND METHODS
An experiment was conducted on eighty freshly extracted tooth specimens which were equally divided into four groups. Each group was brushed with the specifically assigned electric toothbrush to that group, but keeping parameters such as force applied during brushing, storage of tooth before and after brushing, and toothbrushing time same. A total of the 2-month study was done on each tooth specimen. Tooth surface roughness was recorded before and after the toothbrushing experiment to check the difference between surface roughness readings. Scanning electron microscopic (SEM) analysis was done afterward to analyse the surface topography of each group specimens.
STATISTICAL ANALYSIS USED
Paired -test used for intergroup analysis and intragroup analysis was done using Kruskal-Wallis test.
RESULTS
After comparing the baseline and final readings of each group, it has been found that the mean difference between values is highly significant in Group 1 (rotary/oscillatory). The mean rank of Group 1 was least in all four groups, which showed the highest tooth surface abrasion in that group. SEM analysis also revealed that Group 1 tooth specimens had deeper scratches/lines comparatively to other groups.
CONCLUSION
Rotary/oscillatory toothbrush caused the highest tooth surface abrasion when compared with other electronic toothbrushes.
PubMed: 33888942
DOI: 10.4103/jisp.jisp_162_20 -
Frontiers in Bioengineering and... 2024Dental erosion and abrasion pose significant clinical challenges, often leading to exposed dentinal tubules and dentine demineralization. The aim of this study was to...
Dental erosion and abrasion pose significant clinical challenges, often leading to exposed dentinal tubules and dentine demineralization. The aim of this study was to analyse the efficacy of quercetin-encapsulated hollow mesoporous silica nanocomposites (Q@HMSNs) on the prevention of dentine erosion and abrasion. Q@HMSNs were synthesized, characterized, and evaluated for their biocompatibility. A total of 130 dentine specimens (2 mm × 2 mm × 2 mm) were prepared and randomly distributed into 5 treatment groups (n = 26): DW (deionized water, negative control), NaF (12.3 mg/mL sodium fluoride, positive control), Q (300 μg/mL quercetin), HMSN (5.0 mg/mL HMSNs), and Q@HMSN (5.0 mg/mL Q@HMSNs). All groups were submitted to erosive (4 cycles/d) and abrasive (2 cycles/d) challenges for 7 days. The specimens in the DW, NaF, and Q groups were immersed in the respective solutions for 2 min, while treatment was performed for 30 s in the HMSN and Q@HMSN groups. Subsequently, the specimens were subjected to additional daily erosion/abrasion cycles for another 7 days. The effects of the materials on dentinal tubule occlusion and demineralized organic matrix (DOM) preservation were examined by scanning electron microscopy (SEM). The penetration depth of rhodamine B fluorescein into the etched dentine was assessed using confocal laser scanning microscopy (CLSM). The erosive dentine loss (EDL) and release of type I collagen telopeptide (ICTP) were measured. The data were analysed by one-way analysis of variance (ANOVA) with Tukey's test ( = 0.05). Q@HMSNs were successfully synthesized and showed minimal toxicity to human dental pulp stem cells (HDPSCs) and gingival fibroblasts (HGFs). Q@HMSNs effectively occluded the dentinal tubules, resulting in a thicker DOM in the Q@HMSN group. The CLSM images showed more superficial penetration in the HMSN and Q@HMSN groups than in the quercetin, NaF, and DW groups. The Q@HMSN group exhibited a significantly lower EDL and reduced ICTP levels compared to the other groups ( < 0.05). Q@HMSNs hold promise for inhibiting dentine erosion and abrasion by promoting tubule occlusion and DOM preservation.
PubMed: 38405377
DOI: 10.3389/fbioe.2024.1343329