جستجوی مقالات مرتبط با کلیدواژه « dental amalgam » در نشریات گروه « پزشکی »

Understanding the reasons for retreatment of dental restorations is crucial to preventing potential tooth failure. Due to limited information on retreatment causes in our region, this study aims to compare the factors leading to the failure of posterior amalgam and composite restorations.

This cross-sectional, observational study was conducted on patients referred to the restorative department of Ilam Faculty of Dentistry and private clinics who required retreatment of existing posterior restorations. Failure criteria for posterior restorations were evaluated based on established reference guidelines.

 The study found that secondary caries had an odds ratio (OR) of 3.08 (95% CI: 2.85 – 3.29; p < 0.001), indicating a strong association with restoration failure. Additionally, restoration fractures were significantly correlated with retreatment, with an adjusted OR of 2.50 (95% CI: 2.46 – 2.86; p < 0.001).

 Secondary caries emerged as the most common reason for retreatment, regardless of whether composite or amalgam materials were used. Restoration fractures also significantly contributed to the need for retreatment. Therefore, it is essential to consider factors such as restoration material, classification, and the number of restoration levels to reduce the likelihood of retreatment.

Teeth bleaching is an accepted and modern treatment in cosmetic dentistry. Bleaching agents may affect amalgam restorations and increase mercury release; therefore, patients are at increased risk of mercury exposure in the body. The aim of this study was to investigate the effect of polishing and universal bonding application on mercury release from aged amalgams exposed to bleaching.

In this in-vitro experimental study, 64 dental amalgam specimens with dimensions of 3×5×10 were prepared and divided into two experimental and control groups. Each group was further divided into 4 subgroups and received one of the following treatments: no intervention, surface bonding, polishing, or polishing and surface bonding. Subsequently, the samples were immersed in bleaching agent containing 7% hydrogen peroxide and the amount of mercury released after 96h was measured. The results were analyzed by two-way ANOVA and Tukey post hoc tests (α≤0.05).

The results showed that the type of solution (P<0.05) and surface treatment (P<0.001) significantly affected the level of mercury release. However, there was no significant interaction between surface treatment methods in the bleaching group and those in the phosphate buffer group (P=0.621).

Bleaching agents were found to enhance mercury release from dental amalgam. The application of polishing and universal bonding on amalgam surfaces exhibited significant effects on the reduction of the mercury release.

This study aimed to evaluate radiofrequency-induced heating of different amalgam restorations and dental implants during 1.5T magnetic resonance imaging (MRI).

Standardized class I cavities (5 mm long, 3 mm wide, and 3 mm deep) were prepared on the occlusal surface of 45 extracted human third molars. The samples were restored by three different types of amalgam including Cinalux amalgam (non-gamma-2, spherical), GS-80 (non-gamma-2, admix), and GK-110 amalgam (non-gamma-2, admix in silver). As a separate intervention group (G4), five titanium mini drive-lock implants with 2mm diameter and 10mm length were also selected and mounted to the base of the Eppendorf tube with 3mm of the implants extending above the mounting putty. The box containing the specimens was placed parallel to the long axis of the standard head and neck coil of the MRI device (64MHz radio-frequency energy with 25kW amplifier, 1.5T). Temperature fluctuations of the metallic materials in each group were monitored during MRI scans using a calibrated thermometer. One-way ANOVA was used to compare temperature changes among the amalgam groups (P<0.05).

Temperature elevations ranged from 0.21°C to 0.70°C in amalgam restorations and from 0.35 to 0.47°C in dental implants. The temperature changes among the three amalgam agents were not statistically significant.

According to our findings, the radiofrequency-induced heating of amalgam restorations and dental implants during MRI examination can be considered within acceptable ranges. Therefore, amalgam restorations and dental implants can be categorized as "MR safe" in terms of radiofrequency-induced heating during 1.5 T MRI.

Diagnosis of dental caries using cone‑beam computed tomography (CBCT) may be hindered due to several introduced and inherent artifacts. The aim of this study was to evaluate the effect of amalgam fillings on the accuracy of diagnosis of proximal caries in CBCT.

In this in vitro study, 102 extracted human teeth (mandibular and maxillary molars and premolars) were used. Six molars were chosen for mesio‑occluso‑distal amalgam restorations. Before obtaining the CBCT images, the 96 remaining teeth were stabilized in dental sockets of six dry human skulls in a way that the proximal contacts re‑established. Thereafter, six of the molar teeth were replaced by the amalgam‑restored teeth and the second group of images was then obtained. All images were evaluated by two independent observers in the panorama view and the presence or absence of caries was recorded. For histopathologic investigations, the teeth were cut and assessed by an oral pathologist using a stereomicroscope. The McNemar test was used for comparison between CBCT assessments and histopathologic evaluations (P < 0.05 was considered statistically significant). In addition, the receiver operating characteristics curve was utilized to evaluate the diagnostic accuracy in different sections of imaging.

The result sensitivity and specificity of CBCT imaging in the first group of images before placement of the restored teeth were 0.96 and 0.36, respectively. In the second group of images after placement of the restored teeth, these values were 0.78 and 0.18, respectively. Moreover, statistical analysis showed that there is a good agreement in interproximal caries diagnosis between histopathologic and CBCT imaging findings without placement of amalgam restorations (P < 0.001). However, this agreement does not exist after amalgam restorations (P = 0.84).

Diagnosis of proximal caries using CBCT is not an efficient method where there are amalgam restorations adjacent to the suspected teeth.

 Mercury is a neurotoxic element that is released from dental amalgam restorations. Since circumstantial evidence exists that the pathology of multiple sclerosis (MS) disease might be in part caused or exacerbated by inorganic mercury, we conducted a systematic review and meta-analysis using a comprehensive search strategy.

 Data bases (PubMed, Google scholar, Cochrane, Embase, Scopus, Ovid, Proquest, and Web of Science) were searched systematically to find the relationship between dental amalgam and MS. Studies were screened according to a pre-defined protocol. The quality of the articles was evaluated by two individuals. The titles and abstracts of the articles were organized and duplicate articles were discovered with the help of Endnote X5 resource management software. Finally, 6 articles were included in the meta-analysis. Random effect model was chosen to conduct the meta-analysis.

 Pooled mean difference of restoration numbers between two groups was 0.58 (95% CI: 0.33-0.83, P value<0.001) with greater numbers in MS patients. The pooled OR was 1.02 (95% CI, 0.86-1021, P=0.81), which was slightly higher for those with amalgam so they were more likely to develop MS. This slight increase in risk was not statistically significant.

 Although those who underwent a large number of amalgam fillings were at higher risk for MS, the difference between the two groups of patients and controls was statistically insignificant. It seems that the number of amalgam fillings can be an influential factor in the possibility of developing MS.

From the perspectives of longevity, mechanical performance, and economics, amalgam has long been considered the material of choice, especially for certain types of restorations in posterior teeth, including replacement therapy for existing amalgam fillings. In spite of numerous advantages over other filling materials, its use has been decreasing in recent years and the alternative tooth‑colored filling materials are increasingly used. There is a trend towards minimal interventional, adhesive, techniques in dentistry, which are based on adhesion to tooth structure by chemical interaction and/or micromechanical retention. At the same time, the quality and durability of alternative materials have improved. Mercury is the metallic element of concern used in dental amalgam. Mercury is a well‑documented toxicant, with reasonably well‑defined characteristics for the major forms of exposure, involving elemental mercury as well as organic and inorganic mercury compounds. Looking into the kind of practice and its popularity among dentists and the patients in India, even we have to comply with the use of amalgam by implementing the best possible ways to minimize the extent of damage to nature.

This study was conducted to evaluate and compare the effect of using three adhesive systems on the shear bond strength between composite resin and fresh amalgam.

Amalgam samples were assigned into three groups according to the adhesive systems being used prior to the composite resin application. Group A (n= 10): universal self-etch bonding system (Single Bond Universal Adhesive, 3M, Neuss, Germany) was applied and light cured. Group B (n=10): universal self-etch bonding was applied and light cured, followed by a thin layer of nanohybrid flowable composite (Tetric N-Flow, Ivoclar Vivadent, Liechtenstein), then light cured. Group C (n=10): self-adhesive dual-cure luting resin cement (Calibra Universal, Dentsply Sirona, Charlotte, NC) was applied in equal quantity for each sample over amalgam surface. Composite resin was then applied by plastic instrument in a single increment to the height of the hole (2 mm), then celluloid strip was placed and light cured. After thermocycling, a shear bond test was performed.

Resin luting cement interface showed the higher significant bond strength, followed by universal bonding agent − flowable composite interface. The universal bonding interface group yielded the lowest results.

The application of self-adhesive dual-cure luting resin cement resulted in significant increase in bond strength between composite resin and fresh amalgam.

 Recently, a new category of dental bonding agents called universal adhesives has been introduced to the market, which are claimed to be able to create a strong bond between composite resins and teeth, metal surfaces and all types of ceramics alone and without the use of other primers. The aim of this study was to evaluate the performance of universal adhesives in the repair of amalgam restorations with composite resins in comparison with the conventional method.

 In this experimental in vitro study, 80 amalgam blocks were prepared and after abrading the surface with an intraoral sandblaster and performing the aging process, the specimens were divided into 4 groups of 20 each, depending on how each surface was prepared by different bonding in the following order: Single Bond2 (S), Alloy Primer and Single Bond (AS), G-Premio Bond (G) and Alloy Primer and G-Premio Bond (AG). The composite blocks were then cured on the surface of the specimens. Finally, the specimens were tested for micro-shear bond strength (µSBS) using a micro-tensile tester and their cross-section was examined for fracture pattern under a stereomicroscope. Data were analyzed using Kruskal-Wallis, Man Whitney, and chi-square tests. A value of P<0.05 was considered significant.

 The highest and lowest bond strengths belonged to the AG and S groups, respectively. The mean difference of µSBS in the four groups was significant, except in the AS and G groups.

 G-Premio universal bond is able to create sufficient bond strength between composite and amalgam. However, it is recommended to use a combination of Alloy Primer with all bonding systems to improve bond strength.

This study was conducted to compare the shear bond strength (SBS) of orthodontic brackets to amalgam surfaces by two surface treatment methods, two different adhesives, and one intermediate resin and also to evaluate surface roughness after two preparation methods as well as bond failure mode.

In this in‑vitro study forty‑eight amalgam samples were randomly allocated to four groups. In Groups 1–3, specimens were sandblasted with 50 μm aluminum oxide, followed by application of Alloy primer in Groups 1 and 2. In Group 3 Alloy primer had not used. In Group 4, samples were prepared by silica coating using a silane coupling agent. Surface roughness analysis was performed in 10 additional samples after two surface treatments. The brackets in Group 1 were bonded with Transbond XT and those in other groups were bonded with Panavia V5. All specimens were examined for SBS following 5000 times thermocycling at 5°C–50°C. Modified adhesive remnant index was utilized for the bond failure mode. Data analysis was done by one‑way analysis of variance, post hoc Tukey, Kruskal–Walli and Mann–Whitney U tests. Statistical significance was set at P < 0.05.

The findings indicated the mean SBS were low (ranged from 0.19 to 4.66 MPa) and significantly lower in Group 3 than in Group 4 (P = 0.009). Bond failure occurred in adhesive/ amalgam interface in nearly all samples. Silica coating produced significantly lower roughness than sandblast (P = 0.009).

Silica coating had a significant higher bond strength than sandblast without application of Alloy primer. However compared to sandblast with Alloy primer, silica coating did not significantly improve the bond strength. Chemical bond between PanaviaV5 and sandblasted amalgam was not considerable.

The goal of this study was to test the impact of both diabetes type and control via the hemoglobin A1C biomarker on oral health outcomes.

In this observational study, data were extracted from the University of Pittsburgh Dental Registry and DNA Repository and analyzed. From 6,026 subjects, 414 ones with a diagnosis of diabetes were matched by sex, age and ethnicity with 414 individuals without diabetes. A number of statistical approaches (chi-square, Fisher’s exact, Student’s t, Wilcox, and Mann Whitney tests) were used and all comparisons were set with an alpha of 0.05.

Patients with type 1 diabetes experienced xerostomia more often compared to non-diabetic matched pairs (p=0.02). Patients with diabetes (n=414) experienced temporomandibular joint (TMJ) discomfort more often than their non-diabetic matched pairs, as did type 1 diabetic patients alone, in comparison to both their matched pairs and type 2 diabetic patients (p=0.01, p=0.004, and p=0.02, respectively). Among patients grouped by diabetic control, all patients reporting control (n=39) experienced xerostomia more often than their non-diabetic matched pairs (p=0.05). Patients in poor diabetic control experienced restoration failure more often than patients in good control (p=0.04). The experience of restoration failure was no different between patients in good diabetic control and their matched controls (p=0.26). The number of restoration failures was higher in patients in poor control, as compared to their matched non-diabetic controls (p=0.03).

Patients with diabetes experienced xerostomia but not necessarily more severe caries experience, and may be protected from TMJ discomfort. Patients in good control of their diabetes were at no greater risk for restoration failure as compared to non-diabetic patients; however, the patients in poor control were at higher risk for failed restorations.

Streptococcus mutans (S. mutans) is a cariogenic microorganism. The restorative materials which harbor a biofilm with high levels of S. mutans can accelerate the occurrence of dental caries. The purpose of this study was to evaluate the influence of different restorative materials on S. mutans colonization in a simple in-vitro biofilm formation model.

Thirteen discs of each material (nanohybrid resin composite, microhybrid resin composite, and amalgam) were prepared, polished, and sterilized in a gamma radiation chamber. The saliva-free specimens were exposed to the S. mutans bacterial suspension (0.5 McFarland) and were incubated for 4 hours. Afterwards, the specimens were rinsed and sonicated in normal saline. 10µl of the obtained suspension was cultured in a sterile blood agar medium. After 24 hours, the number of colony forming units (CFU) of S. mutans was counted. A sterility test control was considered for each group of materials. The data were analyzed by one-way ANOVA at 5% significance level.

The means and standard deviations of the logarithmic values of the colonies on the surfaces of amalgam, microhybrid, and nanohybrid resin composites were equal to 3.76±0.64, 3.91±0.52 and 3.34±0.74, respectively.

There were no significant differences between the restorative materials in terms of S. mutans adhesion rate. The evaluated resin composites showed comparable numbers of CFUs, which could imply the importance of the polishing procedures.