Aim: The fracture resistance of the post materials used nowadays significantly impacts the fracture type of the post material. The current study aimed to examine the impact of the fracture resistance of PEEK posts, wh...Aim: The fracture resistance of the post materials used nowadays significantly impacts the fracture type of the post material. The current study aimed to examine the impact of the fracture resistance of PEEK posts, whose use as a post material has not yet become widespread, on the fracture pattern that will occur. Materials and Methods: Sixty-six extracted upper central incisor human teeth were used in the study. Six groups of posts were produced from metal, fiber, and PEEK materials (n = 11). Afterward, the fracture resistance test was applied to the samples. Samples were classified according to fracture type as repairable or irreparable. The ANOVA and test were used in statistical analysis. Post-hoc tests were carried out using Tukey’s and Tamhane’s T2 tests. On the other hand, Pearson’s chi-square test and the Fisher-Freeman-Halton test were conducted for comparisons between categorical variables. The statistical significance level was accepted as p Results: According to the fracture resistance test results, the groups where metal personal posts were used displayed higher fracture resistance in comparison with all other groups. According to the results of the optical microscope examination, the incidence of repairable fractures was significantly higher in the PEEK post group with ferrule preparation (p 0.05). Conclusion: In the absence of the ferrule effect, fractures are catastrophic, regardless of the material used. The use of PEEK as a post material contributes to keeping fractures at a repairable level.展开更多
The aim of this study is to investigate the color change of different restoration thicknesses, backgrounds and resin cement colors on lithium disilicate and zirconium reinforced lithium silicate materials in vitro. In...The aim of this study is to investigate the color change of different restoration thicknesses, backgrounds and resin cement colors on lithium disilicate and zirconium reinforced lithium silicate materials in vitro. In this study, IPS emax CAD (LT C14) and Celtra Duo (LT C14) are used as full ceramic materials, and Variolink Esthetic LC (warm, neutral) used as resin cement and Tokuyama Estelite Sigma Quick (A3, A2) is used as composite materials. A total of 160 samples in the form of 40 pieces of 5 × 5 0.4 mm thick 40 pieces of 5 × 5 0.6 mm thick square discs from each of the all-ceramic materials in block form were obtained using a water jet device (DWJ1525-FA;Dardi International Corporation, Nanjing, China). Glass ceramic samples produced in 2 different thicknesses were cemented on 2 different backgrounds with 2 different resin types of cement. Color measurements of the samples before and after cementation were performed on a grey background with spectrophotometer Vita EasyShade V (Vita Zahnfabrik, Bad Sackingen, Germany) and color parameters (L*, a*, b*, ΔE) were calculated according to the CIE Lab (Commission Internationale de L’Eclairage) system. Average values for each group (ΔE) were not affected by ceramic type, material thickness, background color, resin cement color, and the interaction of these four variables (p > 0.05). When the triple interactions between the groups were examined, there were no statistically significant differences (p > 0.05). In the evaluation of pairwise interactions between two groups (material type-material thickness, material type-background color, and thickness of material-background interactions) statistically significant differences (p Implications: The material type, thickness, background and cement color used did not cause any statistically significant color change in lithium disilicate and zirconium-reinforced lithium silicate glass ceramic materials (p > 0.05).展开更多
Introduction: A scanning acoustic microscope (SAM) is an apparatus for imaging acoustic properties. This apparatus can non-invasively and rapidly evaluate the hardness of materials in the elastic region. This device s...Introduction: A scanning acoustic microscope (SAM) is an apparatus for imaging acoustic properties. This apparatus can non-invasively and rapidly evaluate the hardness of materials in the elastic region. This device shows great potential for the diagnosis of dental caries in the clinical setting. However, since the tissue elastic modulus measured using a SAM is a property of the elastic region and the Knoop hardness is a property of the plastic region, the hardness properties differ completely. Therefore, we investigated whether the acoustic impedance measured using a SAM is related to the Knoop hardness, which is used as the standard for removal of carious dentin. Method: Polished sections were prepared from 20 extracted carious wisdom teeth. The acoustic impedance and Knoop hardness were measured for each section. In addition to comparing carious and healthy dentin in SAM images, we evaluated the difference between the carious and healthy dentin in terms of the acoustic impedance and Knoop hardness. We also evaluated the correlation between the Knoop hardness and acoustic impedance. Results: The SAM images were visualized as two-dimensional color images based on the acoustic impedance values. The mean acoustic impedance of carious dentin was significantly lower than that of healthy dentin, showing a similar trend as Knoop hardness. A strong correlation was observed between the two. Discussion: The acoustic impedance values obtained through acoustic microscopy differed significantly between carious and sound dentin. Both types of dentins were visualized using two-dimensional color images. A strong correlation was observed between the acoustic impedance value, which indicates the hardness of the elastic region, and the Knoop hardness, which indicates the hardness of the plastic region. The results of the present study indicate that acoustic impedance accurately reflects the hardness of dentin.展开更多
The Merkel cell-neurite complex initiates the perception of touch and mediates Ab slowly adapting type I responses.Lichen planus is a chronic inflammatory autoimmune disease with T-cell-mediated inflammation,whereas h...The Merkel cell-neurite complex initiates the perception of touch and mediates Ab slowly adapting type I responses.Lichen planus is a chronic inflammatory autoimmune disease with T-cell-mediated inflammation,whereas hyperkeratosis is characterized with or without epithelial dysplasia in the oral mucosa.To determine the effects of lichen planus and hyperkeratosis on the Merkel cell-neurite complex,healthy oral mucosal epithelium and lesional oral mucosal epithelium of lichen planus and hyperkeratosis patients were stained by immunohistochemistry(the avidin-biotin-peroxidase complex and double immunofluorescence methods)using pan cytokeratin,20(K20,a Merkel cell marker),and neurofilament 200(NF200,a myelinated Ab-and Ad-nerve fibre marker)antibodies.NF200-immunoreactive(ir)nerve fibres in healthy tissues and in the lesional oral mucosa epithelium of lichen planus and hyperkeratosis were counted and statistically analysed.In the healthy oral mucosa,K20-positive Merkel cells with and without close association to the intraepithelial NF200-ir nerve fibres were detected.In the lesional oral mucosa of lichen planus and hyperkeratosis patients,extremely rare NF200-ir nerve fibres were detected only in the lamina propria.Compared with healthy tissues,lichen planus and hyperkeratosis tissues had significantly decreased numbers of NF200-ir nerve fibres in the oral mucosal epithelium.Lichen planus and hyperkeratosis were associated with the absence of Ab-nerve endings in the oral mucosal epithelium.Thus,we conclude that mechanosensation mediated by the Merkel cell-neurite complex in the oral mucosal epithelium is impaired in lichen planus and hyperkeratosis.展开更多
Electrical potentials up to 800 mV can be observed between different metallic dental restorations. These potentials produce fields in the mouth that may interfere with microbial communities. The present study focuses ...Electrical potentials up to 800 mV can be observed between different metallic dental restorations. These potentials produce fields in the mouth that may interfere with microbial communities. The present study focuses on the impact of different electric field strengths(EFS) on the growth of Staphylococcus aureus(ATCC 25923) and Escherichia coli(ATCC 25922) in vitro. Cultures of S. aureus and E. coli in fluid and gel medium were exposed to different EFS. Effects were determined by calculation of viable counts and measurement of inhibition zones. In gel medium, anodic inhibition zones for S. aureus were larger than those for E. coli at all field strength levels. In fluid medium, the maximum decrease in the viable count of S. aureus cells was at 10 V·m21. Field-treated S. aureus cells presented ruptured cell walls and disintegrated cytoplasm. Conclusively, S. aureus is more sensitive to increasing electric field strength than E. coli.展开更多
Objective: The aim of this study was to investigate, in vitro, the color changes of the teeth, induced by endodontic sealers. Materials and Methods: Forty-five mature maxillary and mandibular anterior teeth, extracted...Objective: The aim of this study was to investigate, in vitro, the color changes of the teeth, induced by endodontic sealers. Materials and Methods: Forty-five mature maxillary and mandibular anterior teeth, extracted for periodontal reasons, were collected. After the chemo-mechanical instrumentation of the root canal, teeth were filled with four endodontic sealers (Endomethason, AH+, Canason and Apexit). Depending on canal sealers and the CEJ (Cement Enamel Junction), teeth were divided into 8 experimental groups (n = 5) and one control group/CG (n = 5). Teeth color changes (L*a*b*/CIE Commission Internationaled’ Eclaraige) were determinated by a spectrophotometer Vita Easyshade in 4 stages (Baseline, Week 0, 4 and 12). Results: Between the EOCEJ and CG for the parameter L*, there was a statistical significance (p 0.05). The L*a*b* results were: L* (83.6 ± 4.8 → 83.6 ± 4.9);a* (﹣2.68 ± 1.02 → ﹣1.12 ± 0.72) and b* (20.2 ± 4.5 → 24.4 ± 4.2). Conclusions: All endodontic sealers may cause teeth discoloration.展开更多
The aim of this study was to investigate the effects of two bleaching systems on micro hardness, surface roughness and color stability of two novel dental composites. Ormocer based restorative Admira and nano-filled c...The aim of this study was to investigate the effects of two bleaching systems on micro hardness, surface roughness and color stability of two novel dental composites. Ormocer based restorative Admira and nano-filled composite Clearfil Majesty Esthetic were bleached with 10% carbamide peroxide(Opalescence PF) or 35% hydrogen peroxide(Beyond Max 5) and subsequently immersed in four different staining solutions(coffee, tea, red wine, and cola). Distilled water was used as a control. Color measurements were performed with a spectrophotometer. Vickers micro hardness and roughness data were analyzed with twoway analysis of variance for repeated measures. The analysis of variance was used to compare the color change values. Duncan's multiple comparison test was applied to compare the results(α = 5%). ΔEab* values over 3.3 were considered clinically unacceptable. Micro hardness and surface roughness values of the tested composites were decreased significantly after bleaching applications. Red wine and tea storage caused perceptible discolorations in the composite resin materials after 30 days of 3-hour immersion. Home or office bleaching applications can affect the surface properties of resin composites and accelerate the staining process.展开更多
Several capture techniques are used in intraoral optical scanners in the dental market,such as Triangulation(Cerec Omnicam,Dentsply Sirona),Activewave front sampling(3M ESPE)and confocal technology(iTero,Align).The ac...Several capture techniques are used in intraoral optical scanners in the dental market,such as Triangulation(Cerec Omnicam,Dentsply Sirona),Activewave front sampling(3M ESPE)and confocal technology(iTero,Align).The accuracy of intraoral scanners is the most significant focal point for developers to research.This in-vitro study studied the accuracy of confocal scanners launched from 2015-2020(Trios 3,Trios 4,iTero Element;3Shape Trios A/S,Copenhagen,Denmark,and iTero Element2,and iTero Element5D;Align Technologies,San Jose,CA,USA).A 3D printing model modified from the American National Standard No.132 was scanned five times each scanner.Both Trios3 and Trios4 were scanned using regular scan mode(N)and high-resolution mode(HR).All scanning methods followed the recommendations from the manufacturers.Then the digital models were exported and saved as STL files.Various measurements were determined in the digital model from each scan using Rhinoceros 3D Software(Rhino,Robert McNeel&Associates for Windows,Washington DC,USA).Measurements from the 3D printed model were used as control.All data were recorded in Microsoft Excel and then transferred to SPSS.Descriptive statistics were recorded.Multiple comparisons of various measurements were made among the different scanners and with the control using One-way ANOVA and post hoc using Sheffe(p<0.01).The surface area in the X and Y axis ranged from 2–60 mm,while the depth(Z-axis)ranged from 2–8 mm.The Trios and iTero families showed similar accuracy.However,for the diagonal,the Trios series showed better results compared with the iTero series.Within the same brand,different versions showed no significant change regarding accuracy.展开更多
Cobalt-based alloy(Co-30Cr-5.5Mo)is produced by the investment casting process.This alloy complies with the ASTM F75 standard and is widely used in the manufacturing of orthopedic implants because of its high strength...Cobalt-based alloy(Co-30Cr-5.5Mo)is produced by the investment casting process.This alloy complies with the ASTM F75 standard and is widely used in the manufacturing of orthopedic implants because of its high strength,good corrosion resistance and excellent biocompatibility properties.SEM,XRD and microhardness tests are used to examine the mechanical properties of the material.The examined material exhibits the behaviour of indentation size effect(ISE).Our results reveal that Vickers and Knoop microhardness are dependent on indentation test load.The traditional Meyer's law,the proportional specimen resistance(PSR)model and the Hays-Kendall model(HK)are used to analyze the load dependence of the hardness.As a result,the Hays-Kendall model is found to be the most effective to determine the load-independent hardness HLI of CoCrMo alloy.展开更多
Objective To study the influence of carcinogenic factors on tissues and organs of the maxillofacial region(MFR)by measuring the expression of biomarkers in the oral fluid.Methods We recruited 421 patients who were div...Objective To study the influence of carcinogenic factors on tissues and organs of the maxillofacial region(MFR)by measuring the expression of biomarkers in the oral fluid.Methods We recruited 421 patients who were divided into 2 groups:356 patients with a tumour of the MFR and 65 healthy people without somatic pathology in medical history.Results The effects of carcinogenic factors on the expression of biomarkers in the oral fluid in patients with a tumour of the MFR revealed a significant increase in the levels of biomarkers of tobacco use-MMP-8,TIMP-1,TIMP-2,and CA 72-4,CEA and CA 125;frequent use or abuse of alcohol-MMP-8,TIMP-1,TIMP-2,AFP and NSE;use of narcotics-TIMP-1 and TIMP-2;presence of occupational hazards in the medical history-MMP-8,MMP-9,TIMP-1 and TIMP-2;with a diagnostic sensitivity(DS)of over 60%.Also our analysis showed that the use of tobacco was significantly affecting the expression of TIMP-1and CA 125;frequent use or abuse of alcohol-CA 19-9,AFP and CEA;use of drugs had an impact on MMP-8expression.However,the occupational hazards in the medical history did not show a statistically significant effect.Conclusion Factors of carcinogenesis affect the expression of biomarkers in the oral fluid.The expression of the biomarkers of the MFR should be compared with that in the control group of patients with no carcinogenic factors.展开更多
In this study we established a microcomputer based on speech signal processing system and changes of formant frequencies of the vowels/i/accompany the changes in the oral cavity after maxillary surgery and prosthodont...In this study we established a microcomputer based on speech signal processing system and changes of formant frequencies of the vowels/i/accompany the changes in the oral cavity after maxillary surgery and prosthodontic reconstruction. The study found the first formant frequency, for vowel/i/ has no change, while the second formant frequency peak significantly shifted between the preprosthetic and postprosthetic speaking condition after anterior resection of maxillae, and found there is the correlation between the calculation of relative energy error value and the speech intelligible measured aurally (P【0.05).展开更多
Background: The color stability of dental restorative materials is important for long-term clinical success. Objectives: The objective of this study was to examine the effect of thermocycling on the color and transluc...Background: The color stability of dental restorative materials is important for long-term clinical success. Objectives: The objective of this study was to examine the effect of thermocycling on the color and translucency stability of monolithic zirconia. Materials and methods: A total of 80 disc-shaped specimens (1 cm diameter) were produced from monolithic zirconia material, Katana High Translucent (Kuraray Noritake Dental, Kurashiki, Japan). The specimens were prepared in four different thicknesses: 0.5 mm, 1 mm, 1.5 mm and 2 mm. Before thermocycling, color measurements of the specimens were made by a spectrophotometer (Spectro Shade TM MICRO;MHT Optic Research AG, Milan, Italy). After the thermal aging procedure, the color measurement was repeated. Data obtained from the study were analyzed with descriptive statistics, correlation analysis, one-way ANOVA and Tukey’s tests. Results: After thermocycling, the L*, a*, b* values decreased at all thicknesses. The maximum change in the L*, a* and b* values was observed in 0.5-mm-thick specimens, while the least change was observed in 2-mm-thick specimens. The amount of color change in the specimens after thermocycling was found to be the highest in 0.5-mm-thick specimens (ΔE = 0.91 ± 0.02), and the lowest in 2-mm-thick specimens (ΔE = 0.85 ± 0.01). While a statistically significant color change (ΔE) was observed in 0.5-mm-thick specimens (p < 0.05), a statistically insignificant color change (ΔE) was observed (p > 0.05) in 1-mm, 1.5-mm, and 2-mm-thick specimens. After thermocycling, the translucency parameter (TP) values decreased at all thicknesses. The highest change in the TP values was observed in 0.5-mm-thickspecimens (1.09 ± 0.03), while the lowest change was observed in 2-mm-thickspecimens (0.40 ± 0.04). While a statistically significant change in the TP values was observed in 0.5-mm-thick specimens (p < 0.05), there was a statistically insignificant change in the TP values of 1-mm, 1.5-mm and 2-mm-thick specimens (p > 0.05). Conclusion: Although the color and translucency values after thermocycling exhibited statistically significant changes in the 0.5 mm thickness group, a statistically significant difference was not observed in the other thickness groups.展开更多
Objective of this study was to develope low temperature sol-gel coatings for shape memory metal (NiTi) and evaluate their biocompatibility on NiTi suture material. A series of low temperature TiO2 and TiO2-SiO2 sol-ge...Objective of this study was to develope low temperature sol-gel coatings for shape memory metal (NiTi) and evaluate their biocompatibility on NiTi suture material. A series of low temperature TiO2 and TiO2-SiO2 sol-gel coatings were prepared on glass substrates. The silica content of TiO2-SiO2 coatings ranged from 0 to 30 mol%. The coatings were also prepared with polyethyleneglycol (PEG). The contact angle and photocatalytic activity measurements were used to evaluate the surface properties of the coatings. Stability of the coatings was tested in simulated body fluid (SBF). The TiO2-SiO2 90/10 film made with PEG was more hydrophilic, showed photocatalytic activity and was crack-free after the SBF test, thus it was chosen to animal experiment as a new experimental coating. Uncoated NiTi suture and the suture coated with high temperature TiO2 were used as reference materials. NiTi sutures were inserted subcutaneously on the back of rat for four weeks. In routine histological examinations all materials showed good biocompatibility with mild inflammatory cell reaction. No significant differences in the soft tissue response among the materials were observed. Both the high and new low temperature processed sol-gel coatings remained attached on the sutures confirming the suitability of the coating technique on thin NiTi sutures.展开更多
The advantage of electronic devices is to eliminate the subjectivity. Based on individual capabilities, visual perception has its disadvantages. The aim of this study was to find out the possible shade difference betw...The advantage of electronic devices is to eliminate the subjectivity. Based on individual capabilities, visual perception has its disadvantages. The aim of this study was to find out the possible shade difference between the upper and lower teeth, visual perception versus spectrophotometry as well as proving that females are better in visual perception of colour matching. 82 subjects (dental students) of this study determined the color of each other’s natural teeth. The color of 1640 teeth (incisors, canines and premolars), was matched by visual perception and by Vita Easyshade spectrophotometer. The matching was focused on the middle third of buccal surfaces of the examined teeth. In this study, it was found that there was a difference of color between the teeth of the upper and lower jaw. The percentage of the accordance between two methods was 28.35% for all examined teeth. The color determination at central incisors showed the highest value of accordance 40.85%. Based on Vitapan 3D Mastershade, the most frequent color was 2M2.展开更多
Although short implants are seen as alternative treatments that require additional surgical techniques in posterior region, they can be applied to anterior maxilla and various studies are required on this subject. The...Although short implants are seen as alternative treatments that require additional surgical techniques in posterior region, they can be applied to anterior maxilla and various studies are required on this subject. The purpose of this study was to examine and compare the peak von Mises stress distributions in the crown, implant and abutment by using finite element analysis (FEA). Besides, a comparison of the implant-abutment connection types in the short implant with the FEA method was established. A short implant (4 × 5 mm) with a taper-lock connection and a regular implant (4 × 9 mm) with a screw connection were used in maxillary central incisor tooth area. Three different titanium abutments with 0?, 15? and 25? angles were used for abutments. In addition, in order to determine whether the stress change in short implants is due to the length of the implant-abutment connection, a screw was designed for a short implant and it was also evaluated in the same three angles. A total of three groups and nine models were generated. 114.6N load was applied to the cingulum area of the crown at an angle of 135? to the long axis of the crowns. A torque load of 25 Ncm was applied to the regular and short implant screw. Von Mises stress distributions of implants, abutments and crowns were evaluated by using FEA. Increased angle in implants increased von Mises stress values of implant, abutment and crown. Screw connection was found higher at all angles in short implants. Close values were found at different angles in taper-lock short implant crowns. The length and the angle in the bone of implant with the type of implant-abutment connection results in the accumulated stress values. Clinical Implications Taper implant-abutment connection system was found to be more promising in terms of stress accumulation in crowns. Although the amount of stress on the abutment increased due to the length of the implant in short implants, taper implant-abutment connection system slightly reduced related to this increase.展开更多
Occlusal force has the main role in determining the teeth health in general and determining the chewing, muscle and TMJ function. The objective of this study was to find if there was any relation between the preferred...Occlusal force has the main role in determining the teeth health in general and determining the chewing, muscle and TMJ function. The objective of this study was to find if there was any relation between the preferred chewing side and the force, measured by T-scan III system. The total number of 90 (46 female and 44 male) dental students was included in this study. They were asked whether their preferred chewing side was right, left or both. Afterwards, the occlusal forces in habitual occlusion, using T-Scan III Electronic device (IP-CO position mode, MA-mode, MA sensitivity setting) were measured. The data were presented as Mean ± SD. Spearman correlation was used to find the correlation between the occlusal force and chewing side. Differences in P 0.05) and the right side (r = 0.143, P > 0.05) according to the preferred chewing side. In this study, the relation between the preferred chewing side and occlusal force was found.展开更多
The maxillary second molar contains three roots and three canals. Variations of the maxillary second molar are reported in numerous studies in vitro and in vivo. Dentists are required to have adequate knowledge relate...The maxillary second molar contains three roots and three canals. Variations of the maxillary second molar are reported in numerous studies in vitro and in vivo. Dentists are required to have adequate knowledge related to root canal morphology and their possible variations. The aim of this study was to present a case report about a diagnosis and treatment in maxillary second molar with single root and single canal. It is concluded that the diagnosing of these unusual cases is of high importance for successful endodontic treatment of these teeth.展开更多
Dental abnormalities associated with specific syndromes and/or severe systemic abnormalities in tooth number, form or size are challenging cases in dentistry, affecting esthetics and function. 1 Microdontia is used to...Dental abnormalities associated with specific syndromes and/or severe systemic abnormalities in tooth number, form or size are challenging cases in dentistry, affecting esthetics and function. 1 Microdontia is used to term abnormally small teeth that generally the maxillary lateral incisor or third molar is involved. On the other hand, the entire dentition may be affected as well. 1 Prevalence of microdontia range from 1.5%-2%. 2 The definition of severe hypodontia is four or more lacking teeth. 3-5 The prevalence of severe hypodontia was found to be less than 1% of the unselected population. 6 In another study hypo-dontia is seen with a higher incidence in the permanent dentition (3.5%-6.5%), compared to that of the primary one (0.1%-0.9%). 7 The etiology seems to be inheritance in most cases of hypodontia. However, some are caused by mechanical trauma to jaws during tooth formation, by infection or by the effects of cytostatica and radiation during cancer treatment. 6 There are more than 160 syndromes combined with hypo-dontia. 6 Some of them are ectodermal dysplasia, Rieger syndrome and incontinentia pigmenti. In such cases morphological aberrancies as microdontia and conical crowns may be additional features. 6 In addition to the number of lacking teeth, tooth eruption, occlusion and craniofacial parameters are influenced. The present paper reports the use of maxillary and mandibular overdenture removable complete dentures to treat a patient with class Ⅲ skeletal malocclusion, reduced vertical dimension of occlusion and unacceptable esthetics caused by a rare case of hypodontia and microdontia.展开更多
文摘Aim: The fracture resistance of the post materials used nowadays significantly impacts the fracture type of the post material. The current study aimed to examine the impact of the fracture resistance of PEEK posts, whose use as a post material has not yet become widespread, on the fracture pattern that will occur. Materials and Methods: Sixty-six extracted upper central incisor human teeth were used in the study. Six groups of posts were produced from metal, fiber, and PEEK materials (n = 11). Afterward, the fracture resistance test was applied to the samples. Samples were classified according to fracture type as repairable or irreparable. The ANOVA and test were used in statistical analysis. Post-hoc tests were carried out using Tukey’s and Tamhane’s T2 tests. On the other hand, Pearson’s chi-square test and the Fisher-Freeman-Halton test were conducted for comparisons between categorical variables. The statistical significance level was accepted as p Results: According to the fracture resistance test results, the groups where metal personal posts were used displayed higher fracture resistance in comparison with all other groups. According to the results of the optical microscope examination, the incidence of repairable fractures was significantly higher in the PEEK post group with ferrule preparation (p 0.05). Conclusion: In the absence of the ferrule effect, fractures are catastrophic, regardless of the material used. The use of PEEK as a post material contributes to keeping fractures at a repairable level.
文摘The aim of this study is to investigate the color change of different restoration thicknesses, backgrounds and resin cement colors on lithium disilicate and zirconium reinforced lithium silicate materials in vitro. In this study, IPS emax CAD (LT C14) and Celtra Duo (LT C14) are used as full ceramic materials, and Variolink Esthetic LC (warm, neutral) used as resin cement and Tokuyama Estelite Sigma Quick (A3, A2) is used as composite materials. A total of 160 samples in the form of 40 pieces of 5 × 5 0.4 mm thick 40 pieces of 5 × 5 0.6 mm thick square discs from each of the all-ceramic materials in block form were obtained using a water jet device (DWJ1525-FA;Dardi International Corporation, Nanjing, China). Glass ceramic samples produced in 2 different thicknesses were cemented on 2 different backgrounds with 2 different resin types of cement. Color measurements of the samples before and after cementation were performed on a grey background with spectrophotometer Vita EasyShade V (Vita Zahnfabrik, Bad Sackingen, Germany) and color parameters (L*, a*, b*, ΔE) were calculated according to the CIE Lab (Commission Internationale de L’Eclairage) system. Average values for each group (ΔE) were not affected by ceramic type, material thickness, background color, resin cement color, and the interaction of these four variables (p > 0.05). When the triple interactions between the groups were examined, there were no statistically significant differences (p > 0.05). In the evaluation of pairwise interactions between two groups (material type-material thickness, material type-background color, and thickness of material-background interactions) statistically significant differences (p Implications: The material type, thickness, background and cement color used did not cause any statistically significant color change in lithium disilicate and zirconium-reinforced lithium silicate glass ceramic materials (p > 0.05).
文摘Introduction: A scanning acoustic microscope (SAM) is an apparatus for imaging acoustic properties. This apparatus can non-invasively and rapidly evaluate the hardness of materials in the elastic region. This device shows great potential for the diagnosis of dental caries in the clinical setting. However, since the tissue elastic modulus measured using a SAM is a property of the elastic region and the Knoop hardness is a property of the plastic region, the hardness properties differ completely. Therefore, we investigated whether the acoustic impedance measured using a SAM is related to the Knoop hardness, which is used as the standard for removal of carious dentin. Method: Polished sections were prepared from 20 extracted carious wisdom teeth. The acoustic impedance and Knoop hardness were measured for each section. In addition to comparing carious and healthy dentin in SAM images, we evaluated the difference between the carious and healthy dentin in terms of the acoustic impedance and Knoop hardness. We also evaluated the correlation between the Knoop hardness and acoustic impedance. Results: The SAM images were visualized as two-dimensional color images based on the acoustic impedance values. The mean acoustic impedance of carious dentin was significantly lower than that of healthy dentin, showing a similar trend as Knoop hardness. A strong correlation was observed between the two. Discussion: The acoustic impedance values obtained through acoustic microscopy differed significantly between carious and sound dentin. Both types of dentins were visualized using two-dimensional color images. A strong correlation was observed between the acoustic impedance value, which indicates the hardness of the elastic region, and the Knoop hardness, which indicates the hardness of the plastic region. The results of the present study indicate that acoustic impedance accurately reflects the hardness of dentin.
文摘The Merkel cell-neurite complex initiates the perception of touch and mediates Ab slowly adapting type I responses.Lichen planus is a chronic inflammatory autoimmune disease with T-cell-mediated inflammation,whereas hyperkeratosis is characterized with or without epithelial dysplasia in the oral mucosa.To determine the effects of lichen planus and hyperkeratosis on the Merkel cell-neurite complex,healthy oral mucosal epithelium and lesional oral mucosal epithelium of lichen planus and hyperkeratosis patients were stained by immunohistochemistry(the avidin-biotin-peroxidase complex and double immunofluorescence methods)using pan cytokeratin,20(K20,a Merkel cell marker),and neurofilament 200(NF200,a myelinated Ab-and Ad-nerve fibre marker)antibodies.NF200-immunoreactive(ir)nerve fibres in healthy tissues and in the lesional oral mucosa epithelium of lichen planus and hyperkeratosis were counted and statistically analysed.In the healthy oral mucosa,K20-positive Merkel cells with and without close association to the intraepithelial NF200-ir nerve fibres were detected.In the lesional oral mucosa of lichen planus and hyperkeratosis patients,extremely rare NF200-ir nerve fibres were detected only in the lamina propria.Compared with healthy tissues,lichen planus and hyperkeratosis tissues had significantly decreased numbers of NF200-ir nerve fibres in the oral mucosal epithelium.Lichen planus and hyperkeratosis were associated with the absence of Ab-nerve endings in the oral mucosal epithelium.Thus,we conclude that mechanosensation mediated by the Merkel cell-neurite complex in the oral mucosal epithelium is impaired in lichen planus and hyperkeratosis.
文摘Electrical potentials up to 800 mV can be observed between different metallic dental restorations. These potentials produce fields in the mouth that may interfere with microbial communities. The present study focuses on the impact of different electric field strengths(EFS) on the growth of Staphylococcus aureus(ATCC 25923) and Escherichia coli(ATCC 25922) in vitro. Cultures of S. aureus and E. coli in fluid and gel medium were exposed to different EFS. Effects were determined by calculation of viable counts and measurement of inhibition zones. In gel medium, anodic inhibition zones for S. aureus were larger than those for E. coli at all field strength levels. In fluid medium, the maximum decrease in the viable count of S. aureus cells was at 10 V·m21. Field-treated S. aureus cells presented ruptured cell walls and disintegrated cytoplasm. Conclusively, S. aureus is more sensitive to increasing electric field strength than E. coli.
文摘Objective: The aim of this study was to investigate, in vitro, the color changes of the teeth, induced by endodontic sealers. Materials and Methods: Forty-five mature maxillary and mandibular anterior teeth, extracted for periodontal reasons, were collected. After the chemo-mechanical instrumentation of the root canal, teeth were filled with four endodontic sealers (Endomethason, AH+, Canason and Apexit). Depending on canal sealers and the CEJ (Cement Enamel Junction), teeth were divided into 8 experimental groups (n = 5) and one control group/CG (n = 5). Teeth color changes (L*a*b*/CIE Commission Internationaled’ Eclaraige) were determinated by a spectrophotometer Vita Easyshade in 4 stages (Baseline, Week 0, 4 and 12). Results: Between the EOCEJ and CG for the parameter L*, there was a statistical significance (p 0.05). The L*a*b* results were: L* (83.6 ± 4.8 → 83.6 ± 4.9);a* (﹣2.68 ± 1.02 → ﹣1.12 ± 0.72) and b* (20.2 ± 4.5 → 24.4 ± 4.2). Conclusions: All endodontic sealers may cause teeth discoloration.
基金Funded by the Research Fund of Ataturk University(Nos.2009/324,2011/43)
文摘The aim of this study was to investigate the effects of two bleaching systems on micro hardness, surface roughness and color stability of two novel dental composites. Ormocer based restorative Admira and nano-filled composite Clearfil Majesty Esthetic were bleached with 10% carbamide peroxide(Opalescence PF) or 35% hydrogen peroxide(Beyond Max 5) and subsequently immersed in four different staining solutions(coffee, tea, red wine, and cola). Distilled water was used as a control. Color measurements were performed with a spectrophotometer. Vickers micro hardness and roughness data were analyzed with twoway analysis of variance for repeated measures. The analysis of variance was used to compare the color change values. Duncan's multiple comparison test was applied to compare the results(α = 5%). ΔEab* values over 3.3 were considered clinically unacceptable. Micro hardness and surface roughness values of the tested composites were decreased significantly after bleaching applications. Red wine and tea storage caused perceptible discolorations in the composite resin materials after 30 days of 3-hour immersion. Home or office bleaching applications can affect the surface properties of resin composites and accelerate the staining process.
基金the Maxillofacial Prosthodontics and Dental Materials Research Unit,Faculty of Dentistry,Prince of Songkla University and Scholarship Award of Thai Ph.D.Student under Thailand’s Education Hub for Southern Region of ASEAN countries,Prince of Songkla University.
文摘Several capture techniques are used in intraoral optical scanners in the dental market,such as Triangulation(Cerec Omnicam,Dentsply Sirona),Activewave front sampling(3M ESPE)and confocal technology(iTero,Align).The accuracy of intraoral scanners is the most significant focal point for developers to research.This in-vitro study studied the accuracy of confocal scanners launched from 2015-2020(Trios 3,Trios 4,iTero Element;3Shape Trios A/S,Copenhagen,Denmark,and iTero Element2,and iTero Element5D;Align Technologies,San Jose,CA,USA).A 3D printing model modified from the American National Standard No.132 was scanned five times each scanner.Both Trios3 and Trios4 were scanned using regular scan mode(N)and high-resolution mode(HR).All scanning methods followed the recommendations from the manufacturers.Then the digital models were exported and saved as STL files.Various measurements were determined in the digital model from each scan using Rhinoceros 3D Software(Rhino,Robert McNeel&Associates for Windows,Washington DC,USA).Measurements from the 3D printed model were used as control.All data were recorded in Microsoft Excel and then transferred to SPSS.Descriptive statistics were recorded.Multiple comparisons of various measurements were made among the different scanners and with the control using One-way ANOVA and post hoc using Sheffe(p<0.01).The surface area in the X and Y axis ranged from 2–60 mm,while the depth(Z-axis)ranged from 2–8 mm.The Trios and iTero families showed similar accuracy.However,for the diagonal,the Trios series showed better results compared with the iTero series.Within the same brand,different versions showed no significant change regarding accuracy.
基金Supported by the Research Foundation of Mustafa Kemal University under Grant No 08 F 0501.
文摘Cobalt-based alloy(Co-30Cr-5.5Mo)is produced by the investment casting process.This alloy complies with the ASTM F75 standard and is widely used in the manufacturing of orthopedic implants because of its high strength,good corrosion resistance and excellent biocompatibility properties.SEM,XRD and microhardness tests are used to examine the mechanical properties of the material.The examined material exhibits the behaviour of indentation size effect(ISE).Our results reveal that Vickers and Knoop microhardness are dependent on indentation test load.The traditional Meyer's law,the proportional specimen resistance(PSR)model and the Hays-Kendall model(HK)are used to analyze the load dependence of the hardness.As a result,the Hays-Kendall model is found to be the most effective to determine the load-independent hardness HLI of CoCrMo alloy.
文摘Objective To study the influence of carcinogenic factors on tissues and organs of the maxillofacial region(MFR)by measuring the expression of biomarkers in the oral fluid.Methods We recruited 421 patients who were divided into 2 groups:356 patients with a tumour of the MFR and 65 healthy people without somatic pathology in medical history.Results The effects of carcinogenic factors on the expression of biomarkers in the oral fluid in patients with a tumour of the MFR revealed a significant increase in the levels of biomarkers of tobacco use-MMP-8,TIMP-1,TIMP-2,and CA 72-4,CEA and CA 125;frequent use or abuse of alcohol-MMP-8,TIMP-1,TIMP-2,AFP and NSE;use of narcotics-TIMP-1 and TIMP-2;presence of occupational hazards in the medical history-MMP-8,MMP-9,TIMP-1 and TIMP-2;with a diagnostic sensitivity(DS)of over 60%.Also our analysis showed that the use of tobacco was significantly affecting the expression of TIMP-1and CA 125;frequent use or abuse of alcohol-CA 19-9,AFP and CEA;use of drugs had an impact on MMP-8expression.However,the occupational hazards in the medical history did not show a statistically significant effect.Conclusion Factors of carcinogenesis affect the expression of biomarkers in the oral fluid.The expression of the biomarkers of the MFR should be compared with that in the control group of patients with no carcinogenic factors.
文摘In this study we established a microcomputer based on speech signal processing system and changes of formant frequencies of the vowels/i/accompany the changes in the oral cavity after maxillary surgery and prosthodontic reconstruction. The study found the first formant frequency, for vowel/i/ has no change, while the second formant frequency peak significantly shifted between the preprosthetic and postprosthetic speaking condition after anterior resection of maxillae, and found there is the correlation between the calculation of relative energy error value and the speech intelligible measured aurally (P【0.05).
文摘Background: The color stability of dental restorative materials is important for long-term clinical success. Objectives: The objective of this study was to examine the effect of thermocycling on the color and translucency stability of monolithic zirconia. Materials and methods: A total of 80 disc-shaped specimens (1 cm diameter) were produced from monolithic zirconia material, Katana High Translucent (Kuraray Noritake Dental, Kurashiki, Japan). The specimens were prepared in four different thicknesses: 0.5 mm, 1 mm, 1.5 mm and 2 mm. Before thermocycling, color measurements of the specimens were made by a spectrophotometer (Spectro Shade TM MICRO;MHT Optic Research AG, Milan, Italy). After the thermal aging procedure, the color measurement was repeated. Data obtained from the study were analyzed with descriptive statistics, correlation analysis, one-way ANOVA and Tukey’s tests. Results: After thermocycling, the L*, a*, b* values decreased at all thicknesses. The maximum change in the L*, a* and b* values was observed in 0.5-mm-thick specimens, while the least change was observed in 2-mm-thick specimens. The amount of color change in the specimens after thermocycling was found to be the highest in 0.5-mm-thick specimens (ΔE = 0.91 ± 0.02), and the lowest in 2-mm-thick specimens (ΔE = 0.85 ± 0.01). While a statistically significant color change (ΔE) was observed in 0.5-mm-thick specimens (p < 0.05), a statistically insignificant color change (ΔE) was observed (p > 0.05) in 1-mm, 1.5-mm, and 2-mm-thick specimens. After thermocycling, the translucency parameter (TP) values decreased at all thicknesses. The highest change in the TP values was observed in 0.5-mm-thickspecimens (1.09 ± 0.03), while the lowest change was observed in 2-mm-thickspecimens (0.40 ± 0.04). While a statistically significant change in the TP values was observed in 0.5-mm-thick specimens (p < 0.05), there was a statistically insignificant change in the TP values of 1-mm, 1.5-mm and 2-mm-thick specimens (p > 0.05). Conclusion: Although the color and translucency values after thermocycling exhibited statistically significant changes in the 0.5 mm thickness group, a statistically significant difference was not observed in the other thickness groups.
基金supported in part by the National Technology Agency of Finland(40222/05,40171/06)supported by the Biomaterial and Tissue Engineering Graduate School in Finland
文摘Objective of this study was to develope low temperature sol-gel coatings for shape memory metal (NiTi) and evaluate their biocompatibility on NiTi suture material. A series of low temperature TiO2 and TiO2-SiO2 sol-gel coatings were prepared on glass substrates. The silica content of TiO2-SiO2 coatings ranged from 0 to 30 mol%. The coatings were also prepared with polyethyleneglycol (PEG). The contact angle and photocatalytic activity measurements were used to evaluate the surface properties of the coatings. Stability of the coatings was tested in simulated body fluid (SBF). The TiO2-SiO2 90/10 film made with PEG was more hydrophilic, showed photocatalytic activity and was crack-free after the SBF test, thus it was chosen to animal experiment as a new experimental coating. Uncoated NiTi suture and the suture coated with high temperature TiO2 were used as reference materials. NiTi sutures were inserted subcutaneously on the back of rat for four weeks. In routine histological examinations all materials showed good biocompatibility with mild inflammatory cell reaction. No significant differences in the soft tissue response among the materials were observed. Both the high and new low temperature processed sol-gel coatings remained attached on the sutures confirming the suitability of the coating technique on thin NiTi sutures.
文摘The advantage of electronic devices is to eliminate the subjectivity. Based on individual capabilities, visual perception has its disadvantages. The aim of this study was to find out the possible shade difference between the upper and lower teeth, visual perception versus spectrophotometry as well as proving that females are better in visual perception of colour matching. 82 subjects (dental students) of this study determined the color of each other’s natural teeth. The color of 1640 teeth (incisors, canines and premolars), was matched by visual perception and by Vita Easyshade spectrophotometer. The matching was focused on the middle third of buccal surfaces of the examined teeth. In this study, it was found that there was a difference of color between the teeth of the upper and lower jaw. The percentage of the accordance between two methods was 28.35% for all examined teeth. The color determination at central incisors showed the highest value of accordance 40.85%. Based on Vitapan 3D Mastershade, the most frequent color was 2M2.
文摘Although short implants are seen as alternative treatments that require additional surgical techniques in posterior region, they can be applied to anterior maxilla and various studies are required on this subject. The purpose of this study was to examine and compare the peak von Mises stress distributions in the crown, implant and abutment by using finite element analysis (FEA). Besides, a comparison of the implant-abutment connection types in the short implant with the FEA method was established. A short implant (4 × 5 mm) with a taper-lock connection and a regular implant (4 × 9 mm) with a screw connection were used in maxillary central incisor tooth area. Three different titanium abutments with 0?, 15? and 25? angles were used for abutments. In addition, in order to determine whether the stress change in short implants is due to the length of the implant-abutment connection, a screw was designed for a short implant and it was also evaluated in the same three angles. A total of three groups and nine models were generated. 114.6N load was applied to the cingulum area of the crown at an angle of 135? to the long axis of the crowns. A torque load of 25 Ncm was applied to the regular and short implant screw. Von Mises stress distributions of implants, abutments and crowns were evaluated by using FEA. Increased angle in implants increased von Mises stress values of implant, abutment and crown. Screw connection was found higher at all angles in short implants. Close values were found at different angles in taper-lock short implant crowns. The length and the angle in the bone of implant with the type of implant-abutment connection results in the accumulated stress values. Clinical Implications Taper implant-abutment connection system was found to be more promising in terms of stress accumulation in crowns. Although the amount of stress on the abutment increased due to the length of the implant in short implants, taper implant-abutment connection system slightly reduced related to this increase.
文摘Occlusal force has the main role in determining the teeth health in general and determining the chewing, muscle and TMJ function. The objective of this study was to find if there was any relation between the preferred chewing side and the force, measured by T-scan III system. The total number of 90 (46 female and 44 male) dental students was included in this study. They were asked whether their preferred chewing side was right, left or both. Afterwards, the occlusal forces in habitual occlusion, using T-Scan III Electronic device (IP-CO position mode, MA-mode, MA sensitivity setting) were measured. The data were presented as Mean ± SD. Spearman correlation was used to find the correlation between the occlusal force and chewing side. Differences in P 0.05) and the right side (r = 0.143, P > 0.05) according to the preferred chewing side. In this study, the relation between the preferred chewing side and occlusal force was found.
文摘The maxillary second molar contains three roots and three canals. Variations of the maxillary second molar are reported in numerous studies in vitro and in vivo. Dentists are required to have adequate knowledge related to root canal morphology and their possible variations. The aim of this study was to present a case report about a diagnosis and treatment in maxillary second molar with single root and single canal. It is concluded that the diagnosing of these unusual cases is of high importance for successful endodontic treatment of these teeth.
文摘Dental abnormalities associated with specific syndromes and/or severe systemic abnormalities in tooth number, form or size are challenging cases in dentistry, affecting esthetics and function. 1 Microdontia is used to term abnormally small teeth that generally the maxillary lateral incisor or third molar is involved. On the other hand, the entire dentition may be affected as well. 1 Prevalence of microdontia range from 1.5%-2%. 2 The definition of severe hypodontia is four or more lacking teeth. 3-5 The prevalence of severe hypodontia was found to be less than 1% of the unselected population. 6 In another study hypo-dontia is seen with a higher incidence in the permanent dentition (3.5%-6.5%), compared to that of the primary one (0.1%-0.9%). 7 The etiology seems to be inheritance in most cases of hypodontia. However, some are caused by mechanical trauma to jaws during tooth formation, by infection or by the effects of cytostatica and radiation during cancer treatment. 6 There are more than 160 syndromes combined with hypo-dontia. 6 Some of them are ectodermal dysplasia, Rieger syndrome and incontinentia pigmenti. In such cases morphological aberrancies as microdontia and conical crowns may be additional features. 6 In addition to the number of lacking teeth, tooth eruption, occlusion and craniofacial parameters are influenced. The present paper reports the use of maxillary and mandibular overdenture removable complete dentures to treat a patient with class Ⅲ skeletal malocclusion, reduced vertical dimension of occlusion and unacceptable esthetics caused by a rare case of hypodontia and microdontia.
