Secondary Caries in the Posterior Teeth of Patients Presenting to the Department of Operative Dentistry, Shahid Beheshti Dental School

Objective: Secondary caries is a common problem in dental treatments and its occurrence is attributed to several factors. The present study aimed at assessing the prevalence of secondary caries in posterior teeth of patients presenting to the Department of Operative Dentistry, Shahid Beheshti Dental School.Methods: This descriptive study was conducted on 350 patients with 1,339 posterior teeth restored with amalgam or composite resin. Restorations older than 3 years were evaluated. Data regarding presence or absence of secondary caries, age of restoration, location of receiving dental care, tooth brushing technique and use of dental floss and mouthwash were recorded in a questionnaire. Statistical analysis was done using chi-square test.Results: The prevalence of secondary caries was 26% among the understudy patients. Mesio Ocluso Distal restorations (19.2%) had the highest prevalence of secondary caries. Composite restorations had higher prevalence of secondary caries compared to amalgam restorations (p=0.01). Teeth restored in private dental offices had a higher prevalence of secondary caries compared to those restored in university clinics (p=0.007). Patients who used mouthwash had a significantly lower prevalence of caries recurrence (p=0.05).Conclusion: The prevalence of secondary caries in patients presenting to the Department of Operative Dentistry of Shahid Beheshti Dental School was higher in the MOD restorations, composite restorations and teeth restored in private dental offices finally it was less in the patients using mouthwash

The Effect of Different Coating Methods on Resin Band Strength to Zirconia

Objective: A clinical challenge of using zirconia frameworks is to achieve adequate bond with different substrates. This study aimed to evaluate the effect of bioglass and silica coating of zirconia substrates on microshear bond strength of resin cement to tetragonal zirconia.Methods: This laboratory experimental study was conducted on zirconia discs. A total of 120 YTZP zirconia (Zirkonzahn) discs were fabricated and based on surface treatments were categorized into 8 groups of 15 including 1. Control, 2.Sandblast, 3. Etch + bioglass powder coating, 4. Silane + etch + bioglass powder coating, 5. Etch + bioglass slurry coating, 6. Silane + etch+ bioglass slurry  coating.7. Silane + colloidal silica coating, and 8. Silane + etch + colloidal silica coating. Samples were subjected to microshear bond strength testing. In coated groups, thickness of the coating was measured as well. Kruskal Wallis test and ANOVA were applied for intragroup statistical analysis and Dunnett’s test and Mann Whitney U test were used for pairwise comparisons.Results: The mean bond strength of silica-coated samples was significantly lower than the sandblasted specimens (p<0.001). No significant difference was detected in the mean bond strength between specimens with different glass coatings and sandblasted samples. In other words, bond strength of sandblasted and different glass-coated samples was not significantly different. The thickness of coating in the slurry group was significantly less than in other groups.Conclusion: Bioglass coating could effectively increase the bond strength of resin cement to  zirconia in short-term

The Effect of Physicochemical Surface Treatment Methods on Bond Strength of Zirconia to Resin Cement: A Review of the Literature

Objective: Zirconium oxide has gained the spotlight during the recent years as a high strength ceramic material. However, despite its mechanical superiorities, it forms a weak bond with different synthetic substrates and tissues due to its neutral nature and resistance against chemical agents. Therefore, it is important to improve the bonding technique in order to prevent microleakage and increase retention and fracture resistance of the restoration.Literature Review: Since the discovery of zirconium oxide, several surface treatment methods have been evaluated to increase its bond strength to resin cement such as surface grinding with micro- abrasion, burs or abrasive papers, tribochemical silica coating, silicoating, glass micropearls, glaze- on technique, selective infiltration etching, hot etching and use of phosphate ester monomers. The mentioned techniques and related articles are reviewed and discussed in the present study.Conclusion: Despite extensive studies, no consensus has been reached about a specific treatment as the standard protocol for improving the bond strength of zirconia restorations

Smartphone photography as a teledentistry method to evaluate anterior composite restorations

Objective. Today, teledentistry have gain more attention than past due to the advances in technology. The aim of this study was to compare the use of smartphone photography as a method in teledentistry with the face-to-face examination in the evaluation of anterior composite restorations. Materials and Methods. In this study, photographs of 24 composite restorations in patients attended to the clinic of Ardabil Dental School were obtained using a smartphone without any additional equipment and sent by email to 10 remote observers. As a gold standard method, these restorations were evaluated by an experienced expert in restorative dentistry a face-to-face examination. In both methods FDI criteria were used to evaluate the restorations and classified them as acceptable or not. Sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy of the photographic method relative to face-to-face method were calculated. Furthermore the Mann–Whitney U test was used to statistically compare the two methods in detail. Results. The sensitivity, specificity, positive predictive value, and negative predictive value of the smartphone photography method was 69.35%, 48.72%, 87.34%, and 23.75%, respectively. A diagnostic accuracy of 65.97% was obtained. Statistically, in overall the photographic method rated the restorations as better than they were in reality (face-to-face examination) ( p = 0.002 ). Conclusions. The diagnostic accuracy of the method of evaluating anterior composite restorations by smartphone photography was moderate and the use of this method in teledentistry, although was promising, needs to be improved

Global burden and strength of evidence for 88 risk factors in 204 countries and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

Background: Understanding the health consequences associated with exposure to risk factors is necessary to inform public health policy and practice. To systematically quantify the contributions of risk factor exposures to specific health outcomes, the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 aims to provide comprehensive estimates of exposure levels, relative health risks, and attributable burden of disease for 88 risk factors in 204 countries and territories and 811 subnational locations, from 1990 to 2021. Methods: The GBD 2021 risk factor analysis used data from 54 561 total distinct sources to produce epidemiological estimates for 88 risk factors and their associated health outcomes for a total of 631 risk–outcome pairs. Pairs were included on the basis of data-driven determination of a risk–outcome association. Age-sex-location-year-specific estimates were generated at global, regional, and national levels. Our approach followed the comparative risk assessment framework predicated on a causal web of hierarchically organised, potentially combinative, modifiable risks. Relative risks (RRs) of a given outcome occurring as a function of risk factor exposure were estimated separately for each risk–outcome pair, and summary exposure values (SEVs), representing risk-weighted exposure prevalence, and theoretical minimum risk exposure levels (TMRELs) were estimated for each risk factor. These estimates were used to calculate the population attributable fraction (PAF; ie, the proportional change in health risk that would occur if exposure to a risk factor were reduced to the TMREL). The product of PAFs and disease burden associated with a given outcome, measured in disability-adjusted life-years (DALYs), yielded measures of attributable burden (ie, the proportion of total disease burden attributable to a particular risk factor or combination of risk factors). Adjustments for mediation were applied to account for relationships involving risk factors that act indirectly on outcomes via intermediate risks. Attributable burden estimates were stratified by Socio-demographic Index (SDI) quintile and presented as counts, age-standardised rates, and rankings. To complement estimates of RR and attributable burden, newly developed burden of proof risk function (BPRF) methods were applied to yield supplementary, conservative interpretations of risk–outcome associations based on the consistency of underlying evidence, accounting for unexplained heterogeneity between input data from different studies. Estimates reported represent the mean value across 500 draws from the estimate's distribution, with 95% uncertainty intervals (UIs) calculated as the 2·5th and 97·5th percentile values across the draws. Findings: Among the specific risk factors analysed for this study, particulate matter air pollution was the leading contributor to the global disease burden in 2021, contributing 8·0% (95% UI 6·7–9·4) of total DALYs, followed by high systolic blood pressure (SBP; 7·8% [6·4–9·2]), smoking (5·7% [4·7–6·8]), low birthweight and short gestation (5·6% [4·8–6·3]), and high fasting plasma glucose (FPG; 5·4% [4·8–6·0]). For younger demographics (ie, those aged 0–4 years and 5–14 years), risks such as low birthweight and short gestation and unsafe water, sanitation, and handwashing (WaSH) were among the leading risk factors, while for older age groups, metabolic risks such as high SBP, high body-mass index (BMI), high FPG, and high LDL cholesterol had a greater impact. From 2000 to 2021, there was an observable shift in global health challenges, marked by a decline in the number of all-age DALYs broadly attributable to behavioural risks (decrease of 20·7% [13·9–27·7]) and environmental and occupational risks (decrease of 22·0% [15·5–28·8]), coupled with a 49·4% (42·3–56·9) increase in DALYs attributable to metabolic risks, all reflecting ageing populations and changing lifestyles on a global scale. Age-standardised global DALY rates attributable to high BMI and high FPG rose considerably (15·7% [9·9–21·7] for high BMI and 7·9% [3·3–12·9] for high FPG) over this period, with exposure to these risks increasing annually at rates of 1·8% (1·6–1·9) for high BMI and 1·3% (1·1–1·5) for high FPG. By contrast, the global risk-attributable burden and exposure to many other risk factors declined, notably for risks such as child growth failure and unsafe water source, with age-standardised attributable DALYs decreasing by 71·5% (64·4–78·8) for child growth failure and 66·3% (60·2–72·0) for unsafe water source. We separated risk factors into three groups according to trajectory over time: those with a decreasing attributable burden, due largely to declining risk exposure (eg, diet high in trans-fat and household air pollution) but also to proportionally smaller child and youth populations (eg, child and maternal malnutrition); those for which the burden increased moderately in spite of declining risk exposure, due largely to population ageing (eg, smoking); and those for which the burden increased considerably due to both increasing risk exposure and population ageing (eg, ambient particulate matter air pollution, high BMI, high FPG, and high SBP). Interpretation: Substantial progress has been made in reducing the global disease burden attributable to a range of risk factors, particularly those related to maternal and child health, WaSH, and household air pollution. Maintaining efforts to minimise the impact of these risk factors, especially in low SDI locations, is necessary to sustain progress. Successes in moderating the smoking-related burden by reducing risk exposure highlight the need to advance policies that reduce exposure to other leading risk factors such as ambient particulate matter air pollution and high SBP. Troubling increases in high FPG, high BMI, and other risk factors related to obesity and metabolic syndrome indicate an urgent need to identify and implement interventions

In vitro evaluation of the Long-term bond strength of two resin cements to enamel and dentin

  Background and Aims : In this in vitro study, the long-term bond strength of a self-adhesive resin cement and conventional resin cements to human enamel and dentin was compared .   Materials and Methods: 80 sections of intact human third molars were randomly assigned into eight groups according to the cement type [Rely X Unicem (RXU), Rely X ARC (RXA)], bond substrate (enamel, dentin) and the duration of water storage (24 h or 1 year). Rods of cements (0.75×1 mm) were prepared on the top surface of specimens using Tygon tubes. The micro-shear bond strengths of specimens were measured by a micro-tensile tester. Data were analyzed using Wilcoxon signed ranks and Mann Whitney tests ( α =0.05).   Results: The bond strengths of RXA and RXU cements to enamel after 24h were 18.56±4.08 MPa and 14.99±4.17 MPa, and after 1 year were 19.41±6.24 MPa and 15.51±6.17 MPa, respectively. The bond strengths of RXA and RXU cements to dentin were 13.36±4.02 MPa and 14.16±4.69 MPa after 24h , and 14.63±5.96 MPa and 14.08±6.72 MPa after 1 year, respectively. Tooth substrate had significant effect only on the shear bond strength of RXA cement after 24h (P=0.01), while no other significant differences were found in this study (P>0.05).   Conclusion: According to the results of this study, one-step self-adhesive and multi-step conventional resin cements were similarly effective in bonding to enamel and dentin after 1 year water storage

A study on the Frequency of Ectopic Eruption of Permanent First Molar and Canine in Patients Presenting to the university of Ardabil School of Dentistry, 2016- 2018

Background & objectives: Ectopic eruption is a disorder in which the tooth does not follow its usual course and if not diagnosed in a timely manner, leads to occlusal problems. The aim of this study was to determine the frequency of ectopic eruption of the first permanent molar and canine in patients referred to Ardabil dental school. Methods: By observing the panoramic radiographs, recorded from 2016 to 2017, the frequency of ectopic eruption of first permanent molars in children aged 5 to 8 years and permanent canine in children aged 10 to 13 years was determined. The frequency distribution based on sex, involved jaw, unilaterality and bilaterality were evaluated using Chi-Square test. Results: the frequency of ectopic eruption of the first permanent molar and permanent canine was 2.1% and 6.4% respectively. There was no significant difference in the frequency of ectopic eruption of the first molar, based on the patient's gender (p=0.366), jaw (p=0.132), and unilateral or bilateral involvement (p=0.366).Also, there was no significant difference between the frequency of ectopic eruption of permanent canine and the patient's gender (p=0.384), unilateral or bilateral involvement (p=0.056). The ectopic eruption of the permanent canine in the maxilla was greater than the mandible (p=0.012). Conclusions: In this study, the frequency values of ectopic eruption were 2.1% and 6.4% for the first permanent molar and permanent canine respectively that were in the range of other studies reported from other populations