In vitro release of silver ions and expression of osteogenic genes by MC3T3-E1 cell line cultured on nano-hydroxyapatite and silver/strontium-coated titanium plates.

Attempts are ongoing to improve the surface properties of dental implants by application of different coatings, aiming to enhance osseointegration, and decrease the adverse effects of titanium and its alloys used in dental implants. Coating of implant surface with hydroxyapatite (HA) is one suggested strategy for this purpose due to its high biocompatibility and similar structure to the adjacent bone. This study aimed to quantify the release of silver ions and expression of osteogenic genes by MC3T3-E1 cells cultured on nano-HA and silver/strontium (Ag/Sr)-coated titanium plates via the electrochemical deposition method. Plates measuring 10 × 10 × 0.9 mm were fabricated from Ti-6Al-4 V alloy, and polished with silicon carbide abrasive papers before electrochemical deposition to create a smooth, mirror-like surface. After applying homogenous nano-HA coatings with/without silver/strontium on the surface of the plates, the composition of coatings was confirmed by energy-dispersive X-ray spectroscopy (EDS), and their morphological properties were analyzed by scanning electron microscopy (SEM). The coated specimens were then immersed in simulated body fluid (SBF), and the concentration of released sliver ions was quantified by spectroscopy at 7-14 days. The MC3T3-E1 osteoblastic cell line was cultured in osteogenic medium for 7-14 days, and after RNA extraction and cDNA synthesis, the expression of runt-related transcription factor 2 (RUNX2), osteocalcin (OCN), and osteopontin (OPN); osteogenic genes was quantified by polymerase chain reaction (PCR) using SYBR Green Master Mix kit. The expression of genes and the released amount of silver ions were compared between the two groups using the Mann-Whitney U test. The two groups were not significantly different regarding silver ion release at 14 days (P > 0.05). However, silver ion release was significantly higher from nano-HA coatings with silver/strontium at 7 days (P = 0.03). The difference in expression of RUNX2 (P = 0.04), OPN (P = 0.04), and OCN (P = 0.03) genes was also significant between nano-HA coating groups with and without silver/strontium at 7 days, and the expressions were higher in nano-HA with silver/strontium group, but this difference was not significant at 14 days. Addition of silver and strontium to specimens coated with nano-HA increased the release of silver ions within the non-toxic range, and enhanced the expression of osteogenic genes particularly after 7 days.

Improvement of oral health knowledge and behavior of diabetic patients: an interventional study using the social media.

BACKGROUND: Diabetic patients are not often aware of relationship between diabetes mellitus (DM) and periodontal diseases, and the researchers recommend further knowledge enhancement of diabetic patients in this regard. This study aimed to enhance oral health knowledge of diabetic adults via an educational intervention. METHODS: In this interventional study, three private offices of endocrinologists specialized in treatment of DM were selected for the recruitment of participants. In total, 120 diabetic adults (40 from each office) took part in an educational intervention in three groups (patients from each office made up one group): (I) physician-aid, (II) researcher-aid, and (III) social media. In group (I), participants received educational materials (brochure and CD) from their endocrinologist, in group (II) participants received educational materials from researcher. Group (III) joining an educational group in WhatsApp for 3 months. A self-reported standard questionnaire was filled out by the patients before, and after the intervention to assess oral health knowledge. Data were analyzed by SPSS version 21 using independent t-test, Mann-Whitney test, Chi-square test, and ANCOVA. RESULTS: The mean oral health knowledge score increased in all three groups after the educational interventions (P < 0.001); the highest increase occurred in the social media group. Toothbrushing twice daily or more had the greatest improvement in the physician-aid group compared with the other two groups (P < 0.001). The greatest improvement in dental flossing once daily or more occurred in the social media group (P = 0.01). The mean level of the hemoglobin A1c (HbA1c) decreased in all three groups, but not significantly (P = 0.83). CONCLUSION: The results showed that educational interventions enhance oral health knowledge, and improve the behavior of diabetic adults. The education via the social media can be an efficient method for knowledge enhancement of diabetic patients.

Biaxial flexural strength and Weibull characteristics of a resin ceramic material after thermal-cycling.

PURPOSE: The purpose of this in vitro study was to compare the flexural strength and Weibull characteristics of 3 different resin-ceramic materials with a zirconia-reinforced lithium silicate material after thermal-cycling. MATERIAL AND METHODS: Four different computer-aided design and computer-aided manufacturing restorative materials (Vita Enamic, Lava Ultimate, Crystal Ultra, and Vita Suprinity) were tested. A total of 40 Ø12×1.2-mm disks were prepared and divided into 4 groups (n = 10). Their flexural strength was evaluated after 5000 thermal-cycles with a 4-point biaxial flexure test using a universal testing machine. The Weibull modulus and probability of failure were also determined from the biaxial flexural strength data. Data were analyzed with one-way ANOVA and the Tukey pairwise comparison test (α = 0.05). RESULTS: Significant differences were found among the materials in terms of biaxial flexural strength (p < 0.05). Vita Suprinity had the highest mean ±standard deviation flexural strength (289.1 ± 15.1 MPa), and Vita Enamic had the lowest (100.0 ± 3.2 MPa). The highest Weibull modulus was calculated for Crystal Ultra, followed by Vita Enamic, Lava Ultimate, and Vita Suprinity. CONCLUSION: Vita Suprinity had the highest flexural strength when compared with the other materials tested. Crystal Ultra had the highest flexural strength among the resin-ceramic materials. The highest Weibull modulus was calculated for Crystal Ultra and the lowest for Vita Suprinity.

Are there any color match and color correlation between maxillary anterior teeth?

OBJECTIVE: To evaluate the color match and color correlation between maxillary anterior teeth. MATERIALS AND METHODS: CIELab values of 1182 intact maxillary anterior teeth in 197 human specimens were measured through spectrophotometry. ∆E00 color differences between similar regions of the same and different type teeth were calculated and compared with perceptibility and acceptability thresholds using 1-sample t test to evaluate color matches. Regression analyses assessed linear relationships between the color coordinates of similar regions of different type teeth. Percentages of different modes of the color match between the same specimen's teeth (2-tooth/3-tooth color match or color mismatch) were determined. RESULTS: Mean ∆E00 values for the same type teeth were less than 1.8 (p = 1). Mean ∆E00 values for different type teeth were mostly greater than 1.8 (p < 0.001), except for central and lateral teeth in middle (p = 0.29) and incisal (p = 0.75) regions and for lateral and canine teeth in cervical regions (p = 0.33). The 2-tooth color match showed the highest percentage (>50%). CONCLUSIONS: The same type teeth indicated color matches. Central and lateral teeth showed color matches in middle and incisal regions, while lateral and canine teeth disclosed color matches in cervical regions. The corresponding color coordinates of mismatched regions were linearly correlated. CLINICAL SIGNIFICANCE: In order to predict and determine the shade of maxillary anterior teeth and create natural colors for corresponding restorations, some tooth color relationships and equations are presented in this study.

Effect of surface treatment and surface region on the color stainability of a cemented high-translucency monolithic zirconia ceramic after coffee thermocycling.

STATEMENT OF PROBLEM: Restorations should show low color stainability after clinical and laboratory procedures; however, the impacts of surface treatment and surface region on the color stainability of zirconia restorations are unclear. PURPOSE: The purpose of this in vitro study was to evaluate the effect of surface treatment and surface region on the color stainability of a cemented high-translucency monolithic zirconia ceramic after coffee thermocycling. MATERIAL AND METHODS: Thirty high-translucency Ø10×0.5-mm monolithic zirconia disk specimens were divided into 3 groups based on the surface treatment applied: adjusting (A), polishing (P), and glazing (G). Specimens were cemented to composite resin backings and given 10 000 thermocycles in a coffee solution. CIELab values were measured with a spectrophotometer before and after thermocycling in central and marginal surface regions. ΔE00 values were calculated and compared with perceptibility (ΔE00=0.8) and acceptability (ΔE00=1.8) thresholds to interpret the color changes due to coffee thermocycling. Repeated measures ANOVA and Bonferroni tests were used for data analysis (α=.05). RESULTS: Mean ΔE00 values ranged between 0.72 and 1.26. The surface treatment significantly affected the ΔE00 (P=.005); however, the surface region (P=.499) and the interaction of surface treatment and surface region (P=.998) did not affect the ΔE00. The mean ΔE00 values were less than 0.8 for group G, but greater than 0.8 and less than 1.8 for groups A and P. CONCLUSIONS: Glazing provides the lowest color stainability for cemented high-translucency monolithic zirconia, inducing imperceptible color changes after coffee thermocycling.

Accuracy and precision of intraoral scanners for shade matching: A systematic review.

STATEMENT OF PROBLEM: The use of intraoral scanners is rising in prosthetic dentistry; however, systematic analysis of their accuracy and precision for shade matching is scarce. PURPOSE: The purpose of this systematic review was to evaluate the accuracy and precision of intraoral scanners for shade matching. MATERIAL AND METHODS: In addition to a manual search, an electronic systematic search was conducted on MEDLINE/PubMed, EMBASE, Web of Science, Cochrane, and Scopus databases. English-language original studies published between January 1, 2010 and March 1, 2022 with intraoral or digital scanners were chosen based on the keywords of tooth color or shade selection or determination, color or shade matching, accuracy, validity, or trueness, and precision, repeatability, or reproducibility as inclusive criteria. Two reviewers independently performed the literature search, selected the studies, collected the data from the studies included, and evaluated the quality of the studies included using a quality assessment method and the Joanna Briggs Institute Critical Appraisal Checklist for Quasi-Experimental Studies. A third reviewer resolved disagreements. RESULTS: A total of 17 articles concerning the shade matching accuracy and precision of intraoral scanners were selected and reviewed. Among them, 4 articles evaluated only accuracy, 4 articles assessed only precision, and 9 articles investigated both accuracy and precision. Ten articles reported low levels of shade matching accuracy for intraoral scanners, while 11 articles reported high levels of shade matching precision for intraoral scanners. CONCLUSIONS: Based on the current literature, intraoral scanners show acceptable precision but unacceptable accuracy for shade matching.

Effect of oral health promotion interventions on pregnant women dental caries: a field trial.

BACKGROUND: Dental caries is a costly and very common disease, especially in pregnant women. Reasons such as not paying attention to oral health, poor diet and also lack of adequate education in this regard cause this to happen. Performing well-designed educational interventions using primary health system's forces, can improve oral health of pregnant women and help control this disease. We conducted this study to evaluate the effectiveness of some oral health interventions on pregnant women dental caries. METHODS: A field trial study was done in comprehensive Health Centers in Varamin, Tehran, Iran to assess 439 mothers' dental health status from pregnancy up to 2 years after delivery in intervention (n = 239) and control groups (n = 200). Mothers in intervention groups received oral health-related education consisted of nutritional and behavioral messages via either of four methods: A: comprehensive method including all following methods together (n = 74), B: group discussion by dentists (n = 59), C: face to face education by primary health care providers (n = 53), and D: social network applications (n = 53); while those in control group only received routine maternal and oral health care. We used a questionnaire to collect mothers' demographic, socioeconomic and dental care behavior data and also performed oral examinations to assess their DMFT at baseline and 24 months after delivery to evaluate the effectiveness of these educational oral health interventions. RESULTS: From 454 mothers participated the examination session, 18 pregnant women discontinued during the follow-ups and 439 were remained with mean age of 27.47. In the intervention group, the frequency of daily brushing among women increased from 64% at baseline to 85.6% at the last follow-up and the mean D significantly decreased nearly 1unit at same period (P < 0.05). Most and least dental caries changes were in comprehensive intervention group and social network intervention group compared to other intervention groups, respectively. CONCLUSIONS: Performing educational interventions during and after pregnancy using various message delivery methods and messengers (oral health professionals and trained PHCPs), could improve oral health status and behaviors of pregnant and lactating mothers in a feasible and applicable manner.

Can identical dental shade guides be used interchangeably?

OBJECTIVE: To determine if identical dental shade guides can be used interchangeably considering their precision. MATERIALS AND METHODS: Twenty Vita classical (VC) and Vita 3D-Master (VM) shade guides were subjected to spectrophotometric measurements and their CIELab values were measured in three shade tab regions: incisal, middle, and cervical and also in total. The mean L*, a*, and b* values for analogous shade tabs were calculated to identify CIELab values for typical shades. ∆E00 color differences between a typical shade and its analogous shade tabs were measured. ∆E00 values were compared with perceptibility (∆E00  = 0.8) and acceptability (∆E00  = 1.8) thresholds using one-sample t test (α = 0.05). An error was considered when the ∆E00 value was greater than the threshold. Subsequently, the shade guides' precision scores were calculated. RESULTS: Mean ∆E00 values ranged between 0.3 and 0.5 for VC tabs and between 0.3 and 0.6 for VM tabs. Precision scores for both shade guides ranged from 83.3% to 100%, considering the perceptibility threshold. Regarding the acceptability threshold, precision scores for VC ranged from 93.3% to 100%, while the precision scores for VM were 100%. CONCLUSIONS: Owing to high precision of VC and VM, identical dental shade guides can be used interchangeably. CLINICAL SIGNIFICANCE: Using identical dental shade guides interchangeably may affect the color results of restorative treatments. This study identified high levels of precision for identical shade tabs of Vita classical and Vita 3D-Master across different batches. Thus, similar dental shade guides can be used interchangeably.

Community-based interventions to reduce dental caries among 24-month old children: a pilot study of a field trial.

BACKGROUND: Early childhood caries (ECC) is the most common dental disease among children worldwide, leading to many difficulties on child's growth. As WHO mentioned, educational interventions in addition to interprofessional collaboration are needed to achieve proper ECC prevention. In present study we've aimed to evaluate the effectiveness of some oral health promotion interventions to reduce dental caries among 24-month old children. METHODS: A field trial study was conducted amongst 439 mothers from pregnancy up to 24 months after delivery in Public Health Centers in Varamin, Tehran, Iran. Participants were allocated to intervention (n = 239) and control groups (n = 200). Demographic, socioeconomic status and dental care behavior data were collected using a questionnaire. The content of our study intervention consisted of nutritional and behavioral oral health-related messages. Mothers received messages via either of four methods (A: comprehensive method including all other methods together (n = 74), B: group discussion by dentists (n = 59), C: face to face education by primary health care providers (n = 53), and D: social network (n = 53). The control group received routine maternal and oral health care. To assess the effectiveness of interventions on promoting children's oral health, the oral health-related behaviors data, the number of decayed teeth (d), and being caries free at the age of two were considered. RESULTS: Among the 436 examined children, with a mean age of 23.7 months, 48.2% were male. The frequency of using finger toothbrush increased from 53.4% to 89.8% in all intervention groups. The mean (SD) of decayed teeth at 24 months in intervention and control group were 0.36 (0.93) and 1.61 (2.61), respectively. All the four intervention groups, except social network, had more chance of being caries free compared to control group (P value < 0.05). Analysis showed that children in comprehensive intervention group had a higher chance of being caries free compared to all other groups, after adjustment for covariates. CONCLUSIONS: Performing oral health interventions could help the prevention of dental caries in newborn children. Also, using a combination of different methods of sending messages can have the best results in promoting oral health.

Color match of high translucency monolithic zirconia restorations with different thicknesses and backgrounds.

OBJECTIVE: To assess the effects of ceramic thickness and background type on the color match of high translucency monolithic zirconia restorations. MATERIALS AND METHODS: Fifty A2 shade high translucency zirconia disk specimens with five different thicknesses (0.7, 0.9, 1.1, 1.4, 1.6 mm) were placed on 12 backgrounds: A1, A2, A3, A3.5, B1, and B2 shade composite resin, A3 shade zirconia, nonprecious gold-colored alloy, nickel-chromium alloy, amalgam, and A2 and A3 shade tooth. Color measurements were performed to determine the specimens' CIELab values. CIEDE2000 formula was used to determine ΔE00 color differences between specimens and A2 VITA classical shade (target). The ΔE00 values were compared with perceptibility (0.8) and acceptability (1.8) thresholds to assess color matches. Data were analyzed using repeated measures ANOVA, Bonferroni, and 1-sample t tests (P < .05). RESULTS: Mean ΔE00 values ranged between 1.3 and 5.7. Ceramic thickness, background type, and their interaction significantly affected the ΔE00 (P < .001). Ceramic thicknesses of ≥1.1 mm with the A2 or A3 shade tooth background showed 0.8 < ΔE00 ≤ 1.8 producing acceptable color matches. CONCLUSIONS: High translucency monolithic zirconia restorations with a minimum thickness of 1.1 mm on tooth backgrounds could create acceptable color matches; however, with other backgrounds tested, they could not. CLINICAL SIGNIFICANCE: Ceramic thickness and background type affect the color of high translucency monolithic zirconia restorations. A minimum zirconia thickness of 1.1 mm and normal color tooth structures, as a background, are essential for achieving the acceptable color match of these restorations.

Association between C-reactive protein and gestational diabetes: a prospective study.

Studies that examined the impacts of inflammatory factors on gestational diabetes mellitus (GDM) are very sparse. The purpose of this study was to investigate the relationship between C-reactive protein (CRP) and the risk of GDM. Pregnant women who fulfilled the inclusion criteria and their gestational ages were below 10 weeks were recruited to this cohort study and were followed up until the 24-28 weeks of gestation. At the first pre-natal care visit blood samples were taken from all the pregnant women to investigate the serum concentration of CRP and fasting blood sugar. At 24-28 weeks of gestation, an oral glucose tolerance test was done to diagnose GDM as routine. About 5% of the women participating in the study were diagnosed as having GDM. There was a significant association between the increased serum concentration of CRP in the first trimester and the risk of GDM. The risk of GDM in women with the highest serum concentration of CRP is three times higher than that of women with the lowest serum concentration of CRP. Systemic inflammation can be associated with increased risk of gestational diabetes.Impact statementWhat is already known on this subject? Multiple studies have shown that chronic inflammation can increase the risk of developing type2 diabetes. There is incertitude as to the best attitude for screening and diagnosis of GDM. The studies were examined the impacts of inflammatory factors on GDM is very restricted.What do the results of this study add? CRP level measurement in the first trimester can be considered as a screening test. This is an easy and cost-effective test to make decision for performing oral glucose tolerance test at 24-28 weeks of pregnancy.What are the implications of these findings for clinical practice and/or further research? The results of this study could give physicians and other health care providers the hint that increasing serum CRP levels in early pregnancy can be a risk factor for gestational diabetes.

Reliability and validity of Persian version of Brief Self-Control Scale (BSCS) in motorcyclists.

Objective: The present study aimed to investigate the validity and reliability of the Persian version of brief self-control scale (BSCS) in Iranian motorcyclists.Methods: The original English questionnaire of BSCS has been translated into Persian using the direct-reverse approach. A total of 130 motorcyclists aged 18-65 years old in Iran-Kashan completed the questionnaire. Validity was determined by content validity methods, structural validity through factor analysis, and also the convergence and divergence validity using Spearman correlation coefficient. The intra class correlation coefficient (ICC) was calculated to estimate the reliability of the self-control tool. Reliability was calculated using Cronbach's alpha.Results: The mean and standard deviation of the age at the time of study was 38.5 ± 13.5 years old and all of the subjects were male. Cronbach's alpha coefficient of the whole questionnaire (BSCS) was 0.81, which was good in this regard. The ICC coefficient was 0.88 with confidence interval of (0.8-0.93), which confirmed the repeatability of this tool. Exploratory factor analysis (EFA) yielded a two-factor solution accounted for 42% of the observed variance.Conclusion: This study showed that Persian version of BSCS has a good reliability and validity for self-control in the Persian language community.Key pointsThe Brief Self-Control Scale (BSCS) has good internal consistency.The Brief Self-Control Scale (BSCS) has acceptable reliability.Brief Self-control Scale (BSCS) has acceptable validity and reliability in the population studies.

Effect of Resin Cement Brand on the Color of Zirconia-Based Restorations.

PURPOSE: The purpose of this in vitro study was to evaluate the effect of resin cement brand on the color of zirconia-based restorations. MATERIALS AND METHODS: Ninety A2 shade veneered zirconia disc specimens (0.5 mm zirconia thickness, 1 mm veneer thickness, 10 mm diameter) and 90 A3.5 shade composite resin background specimens (10 mm height, 10 mm diameter) with a superficial cement space (0.1 mm depth, 8 mm diameter) were fabricated. The zirconia specimens were cemented to the background specimens using universal resin cements: RelyX Unicem 2 (RU), PANAVIA SA Cement Plus (PS), and NX3 Nexus (NN). CIELab values were measured with a spectrophotometer before and after cementation. ∆E values were calculated to determine the color differences between before and after cementation of specimens (∆E1 ), and between the A2 VITA classical shade tab and specimens before cementation (∆E2 ) and after cementation (∆E3 ). The ΔE values were compared with an acceptability threshold (ΔE = 3.7) to evaluate color changes/matches. Welch, 1-way ANOVA, Games-Howell, Tukey HSD, and 1-sample t test were used to analyze data (p < 0.05). RESULTS: Mean ΔE1 values were 0.6 ± 0.3 for RU, 0.8 ± 0.4 for PS, and 0.6 ± 0.2 for NN. Resin cement brand significantly affected the ΔE1 (p = 0.029) and the ΔE3 (p < 0.001). Mean ΔE3 values were 3.6 ± 0.3 for RU, 3.5 ± 0.3 for PS, and 3.9 ± 0.3 for NN. RU (p = 0.960) and PS (p = 0.999) showed a color match, but NN did not (p < 0.001). CONCLUSIONS: The resin cement brand affected the color match of zirconia-based restorations. Although the tested cements created minor color changes, RU and PS were better than NN for color match. The use of resin cements with the corresponding shade to the target shade is indicated.

Influence of coping and veneer thickness on the color of zirconia-based restorations on different implant abutment backgrounds.

STATEMENT OF PROBLEM: The effects of coping and veneer thickness on the color of zirconia-based restorations are unknown. PURPOSE: The purpose of this in vitro study was to evaluate the influence of coping and veneer thickness on the color of zirconia-based restorations on different implant abutment backgrounds and to define minimum coping and veneer thicknesses for the backgrounds investigated to achieve a target color. MATERIAL AND METHODS: Thirty zirconia disk specimens with thicknesses of 0.4, 0.6, and 0.8 mm and 30 veneering ceramic disk specimens with thicknesses of 0.8, 1.0, and 1.2 mm were fabricated. Three backgrounds were prepared: titanium alloy, zirconia ceramic, and base metal alloy. The zirconia specimens were placed on the backgrounds, and the veneering ceramic specimens were located on the zirconia specimens. Spectrophotometric measurements were made to determine CIELab values. Color difference (ΔE) values were calculated to measure color differences between the specimens and the A2 VITA classical shade tab. ΔE values were compared with a perceptibility threshold (ΔE=2.6). Repeated measures ANOVA, Bonferroni test, and 1-sample t test were used to analyze data (α=.05). RESULTS: Mean ΔE values ranged from 2.0 to 9.8. Coping thickness, veneer thickness, and their combination significantly affected ΔE (P<.001). CONCLUSIONS: To achieve the target color with zirconia-based restorations, regardless of the backgrounds tested, the minimum thickness of zirconia coping should be 0.6 mm, and the minimum thickness of veneering ceramic should be 1.2 mm.

Oral health status in relation to socioeconomic and behavioral factors among pregnant women: a community-based cross-sectional study.

BACKGROUND: Oral health of women during pregnancy is an important issue. Not only it can compromise pregnancy outcomes, but also it may affect their newborn's overall health. The aim of this study was to assess the oral health status and associated factors in pregnant women. METHODS: A cross-sectional study was conducted amongst 407 pregnant women in the second and third trimester of pregnancy in Varamin, Iran. Oral health status was examined, and demographic, socioeconomic status and dental care behavior data were collected. Oral health indices included periodontal pocket, bleeding on probing (BOP) and decayed, missed, filled teeth (DMFT). Regression analysis of DMFT was used to study the association between demographic, dental care behaviors indicators and outcome variables using the count ratios (CR) and 95% confidence intervals (CI). RESULTS: The mean (SD, Standard Deviation) age of participants was 27.35 (5.57). Daily brushing, flossing habit were observed in 64.1, and 20.6% of mothers, respectively. Mean (SD) of DMFT, D, M, F were 10.34(5.10), 6.94(4.40), 2.22 (2.68) and 1.19(2.23), respectively. Women older than 35 years had significantly more DMFT [CR = 1.35 (95% CI 1.13; 1.60)], less D [CR = 0.75 (95% CI 0.59; 0.94)], and more M [CR = 3.63 (95% CI 2.57; 5.14)] compared to women under 25 years after controlling for education and dental care behaviors. Women with academic education had significantly less decayed teeth [CR = 0.63 (95% CI 0.48; 0.84)], compared to women with under 12 years of education. CONCLUSIONS: Oral health status of pregnant women was not satisfactory, having an average of seven decayed teeth in their mouth.

Effect of Thickness of Zirconia Ceramic on Its Masking Ability: An In Vitro Study.

PURPOSE: Color-masking ability of zirconia ceramics as coping materials has not been clearly understood in zirconia-based restorations. This in vitro study aimed to evaluate the effect of zirconia ceramic thickness on its masking ability, and to define a thickness cutoff for the tested ceramic. MATERIALS AND METHODS: Ninety zirconia disc specimens, in nine thickness groups including 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, and 2 mm were fabricated. A white substrate and a black substrate were prepared. The disc specimens were placed onto the substrates for spectrophotometric measurements. A spectrophotometer measured L* , a* , and b* color attributes for the specimens. ΔE value was calculated to determine the color difference of specimens on the white and black substrate. Then the ΔE values were compared with an acceptable clinical threshold (ΔE = 5.5) and an ideal threshold (ΔE = 2.6). Welch test, Games-Howell Post Hoc, one-sample t-test, and a regression analysis were performed (p < 0.05). RESULTS: The means of ΔE values for the thickness groups of 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, and 2 mm were 13.0, 11.9, 9.7, 5.0, 4.2, 3.9, 2.2, 1.9, and 1.5, respectively. A significant difference was found in the ΔE value among the groups (p < 0.0001). An exponential relation was detected between the thickness and the ΔE by the regression analysis (∆E = 25.68e-1.45 (thickness) ). CONCLUSIONS: The masking ability increased as the zirconia ceramic thickness increased. The tested zirconia ceramic had an acceptable clinical masking ability with a minimum thickness of 1 mm, and an ideal masking ability with a minimum thickness of 1.6 mm.

Effect of coping thickness and background type on the masking ability of a zirconia ceramic.

STATEMENT OF PROBLEM: The masking ability of zirconia ceramics as copings is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the effect of coping thickness and background type on the masking ability of a zirconia ceramic and to determine zirconia coping thickness cut offs for masking the backgrounds investigated. MATERIAL AND METHODS: Thirty zirconia disks in 3 thickness groups of 0.4, 0.6, and 0.8 mm were placed on 9 backgrounds to measure CIELab color attributes using a spectrophotometer. The backgrounds included A1, A2, and A3.5 shade composite resin, A3 shade zirconia, nickel-chromium alloy, nonprecious gold-colored alloy, amalgam, black, and white. ΔE values were measured to determine color differences between the specimens on the A2 shade composite resin background and the same specimens on the other backgrounds. The color change (ΔE) values were compared with threshold values for acceptability (ΔE=5.5) and perceptibility (ΔE=2.6). Repeated measures ANOVA, the Bonferroni test, and 1-sample t tests were used to analyze data (α=.05). RESULTS: Mean ΔE values ranged between 1.44 and 7.88. The zirconia coping thickness, the background type, and their interaction affected the CIELab and ΔE values (P<.001). CONCLUSIONS: To achieve ideal masking, the minimum thickness of a zirconia coping should be 0.4 mm for A1 and A3.5 shade composite resin, A3 shade zirconia, and nonprecious gold-colored alloy, 0.6 mm for amalgam, and 0.8 mm for nickel-chromium alloy.

Effect of thickness of monolithic zirconia ceramic on final color.

STATEMENT OF PROBLEM: Achieving excellent esthetics with monolithic zirconia restorations is challenging, and the impact of monolithic zirconia thickness on the final color is unclear. PURPOSE: The purpose of this in vitro study was to assess the effect of thickness of monolithic zirconia ceramic on its final color and to define the minimum thickness needed to gain an acceptable final color. MATERIAL AND METHODS: Sixty monolithic zirconia disk specimens with a 10-mm diameter and 3 different thicknesses (0.7, 0.9, and 1.1 mm) were fabricated from 2 zirconia brands. The specimens were divided into 6 groups of 10 based on the thickness and brand. All the specimens were colored with an A2 shade liquid. The specimens were placed on an A4 shade substrate, and their CIELab values were measured with a spectrophotometer. ΔE values were calculated to determine color differences between the specimens and the A2 VITA classical shade tab. The ΔE values were compared with an acceptability threshold (ΔE=3.3). Two-way ANOVA, the Bonferroni test, and 1-sample t test were used to analyze data (α=.05). RESULTS: Mean ΔE values ranged between 2.4 and 4.1. The zirconia thickness affected the ΔE (P<.001); however, the zirconia brand did not affect the ΔE (P=.059). The mean ΔE values for the zirconia thickness of 0.7 mm for both brands were more than the threshold (P<.05). CONCLUSIONS: The thickness of monolithic zirconia ceramic affected its final color. The minimum thickness of a monolithic zirconia ceramic should be 0.9 mm to gain the acceptable final color.

Offspring sex ratio of Iranian dentists.

OBJECTIVE: To assess the impact of occupational factors on the sex ratio of dentists' children. METHODS: A randomly selected 501 Iranian dentists participated in a telephone interview. The participants were contacted by their mobile number to answer questions about demographic variables (gender, age, marriage status), practice-related variables (year of graduation as general or specialist dentist, years of clinical work, working hours, average number of radiographs taken in a day, and spouse's job), and questions about their children (number, gender and date of birth of each child). Kruskal-Wallis and Chi-square tests served for statistical evaluation. RESULTS: Of all participating dentists, 71 % were men, about two-thirds were 35- to 50-year olds, and 89 % were married. In total, the dentists had 768 children; about 21 % had no child. Of all the children, 54 % were boys (overall sex ratio = 1.17). The offspring sex ratio was 1.13 among male dentists, 1.50 for female dentists, and 1.44 when both parents were dentists. Higher percentages of boys were prevalent among female dentists, younger dentists, and general dental practitioners (p < 0.008). CONCLUSION: Demographic and practice-related factors showed some impact on proportions of both sexes of dentists' children in this study. However, the result needs evaluation in further studies.

Knowledge of and Attitude Toward Preventive Care Among Iraqi Dentists and Senior Dental Students: A Cross-Sectional Study.

OBJECTIVES: Acquiring knowledge and maintaining a positive mindset are essential for dental care providers to offer optimal dental services. Dental professionals are expected to follow preventive dentistry principles to ensure the best oral health maintenance for their patients, as prevention is a key component of public health initiatives. This study aims to assess the knowledge and attitudes toward preventive dental care among Iraqi dentists and senior dental students. METHODOLOGY: A cross-sectional study, conducted from June to August 2023, involved 876 Iraqi dentists and 587 senior dental students in Baghdad, utilizing a physically paper-based self-administered questionnaire. Participants' level of knowledge was assessed based on a 5-point Likert scale to 12 statements on preventive dental care. Their attitudes were inquired by selecting one option from a 7-point Likert scale on four pairs of bipolar adjectives describing preventive dentistry. Higher scores were considered more accurate knowledge and more positive attitudes. Statistical evaluation included the Chi-square test and regression analysis. RESULTS: In total, data from 841 dentists and 567 students were analyzed (response rate: 96%). Around 90% of dentists (N=745) and students (N=502) acknowledged the impact of sugar, sealant, and water fluoridation on dental caries, but about 80% of dentists (N=662) and students (N=446) undervalued the role of fluoridated toothpaste. Women (OR=1.4, 95% CI: 1.02-2.1) and dentists, within one year of their graduation (OR=1.9, 95% CI: 1.1-3.5), exhibited higher levels of knowledge. More favorable attitudes towards preventive dentistry were associated with a higher level of knowledge among dentists (OR=1.6, 95% CI: 1.2-2.3). Regarding dental students, those from private dental schools showed higher scores of knowledge than their counterparts from public schools (OR=2.1, 95% CI: 1.3-3.4). The majority of participants held the belief that preventive dentistry is beneficial for the community but just about 60% of dentists (N=477) and students (N=300) exhibited a positive attitude toward the economic advantages of preventive dentistry for dentists, as well as the ease of engaging in preventive dental practices. CONCLUSIONS: The dentists and dental students in this study demonstrated satisfactory knowledge and a favorable attitude toward most aspects of preventive dentistry. However, deficiencies were noted in certain areas, such as the application of topical fluoride for preventing dental caries, as well as a substantial proportion of individuals who lacked a positive perspective on the economic benefits of preventive dentistry. Hence, there is a clear need for educational interventions during their undergraduate training and postgraduate continuing education to enhance their knowledge levels and cultivate a more positive attitude towards preventive dentistry.