Microleakage effect of in-office bleaching on two types of nanohybrid composites with or without surface sealer

BACKGROUND

Bleaching is a highly common method used nowadays to treat tooth discolouration because it is a significant cosmetic issue, particularly with anterior teeth, however bleaching itself results in microleakage.

OBJECTIVE

This study aims to evaluate the impact of in-office bleaching on class V restoration microleakage with type 1 and type 2 composite restorations.

METHODS

Three hundred and twenty healthy, caries-free removed human anterior teeth were used in this in-vitro study. All extracted teeth had their buccal and lingual surfaces uniformly prepped for class V cavities. The 120 removed teeth were divided into two groups, with Group 1 receiving Tetric N-Ceram nanohybrid composite restorations and Group 2 receiving 3 M Filtek Z350 XT nanohybrid composite restorations. Groups 1 and 2 were further broken into four more subgroups of four each. The restorations were sealed with a G-Coat Plus resin. The p-value was kept at 0.005 for the data analysis using the Chi-square and Fisher exact tests.

RESULTS

Allocating microleakage among 320 study models revealed that 141 (44.1%) study samples had no microleakage, whereas 20 (6.3%), 54 (16.9%), and 105 (32.8%) study samples had microleakage up to, between, and greater than two-thirds of cavity depth. With a statistically significant p-value of 0.001, no microleakage was discovered in 85 (53.1%) lingual surfaces with Tetric N-Ceram nanohybrid composite restoration and 56 (35%) buccal surfaces with 3M Filtek Z350 XT nanohybrid composite restoration. 19.1% of samples of N-Ceram that were sealed and not bleached had no microleakage, according to analysis of microleakage across several groups. With a p-value of 0.001, the distribution of microleakage among various clusters was statistically notable.

CONCLUSION

According to the findings of the study, hydrogen peroxide bleaching has an enhanced impact on micro escape during dye dispersion. Both with and without bleaching, resin coating can be utilised to minimise marginal microleakage.

Mechanical and Thermal Stress Analysis of Cervical Resin Composite Restorations Containing Different Ratios of Zinc Oxide Nanoparticles: A 3D Finite Element Study

Due to an increase in prevalence of cervical lesions, it is important to use appropriate restorative materials to reduce the incidence of secondary lesions. Owing to having antibacterial properties, cervical composite restorations containing different ratios of Zinc Oxide nanoparticles (ZnO NPs) have been analyzed using the Finite Element method to determine the optimal incorporation ratio from mechanical and thermal perspectives. A numerical simulation is conducted for a mandibular first premolar with a cervical lesion (1.5 × 2 × 3 mm³) restored with composites containing 0 to 5% wt. ZnO NPs. Subsequently, the samples are exposed to different thermo-mechanical boundary conditions, and stress distributions at different margins are examined. The accumulated stress in the restoration part increases for the 1% wt. sample, whereas the higher percentage of ZnO NPs leads to the reduction of stress values. In terms of different loading conditions, the least and most stress values in the restoration part are observed in central loading and lingually oblique force, respectively. The change in the surface temperature is inversely correlated with the ratio of ZnO NPs. In conclusion, the composite containing 5% wt. ZnO NPs showed the most proper thermo-mechanical behavior among all samples.

Treatment of Tooth Wear Associated with Reduced Occlusal Vertical Dimension Using Direct Composite Restorations and a Removable Prosthesis

Tooth wear is increasing in prevalence within the United Kingdom. Treatment of tooth surface loss can be daunting for both the clinician and patient. However, use of additive resin composite restorations is a minimally invasive treatment modality. This case illustrates the treatment of tooth surface loss in both the maxillary and mandibular arches with direct composites restorations using putty indices generated from a diagnostic wax-up recorded in centric relation. The tooth surface loss had resulted in reduced restorative space on the right hand side. The restorative treatment involved increasing the anterior vertical dimension, enabling the provision of a cobalt-chrome partial denture. This case shows the restoration of form, function and aesthetics using a reorganised occlusal approach.

Fall of amalgam restoration: a 10-year analysis of an Australian university dental clinic

BACKGROUND

The use of amalgam in Dentistry has decreased since the 1980s. This study aimed to (i) assess the time trend in the usage of amalgam and composite in posterior teeth at Griffith University Dental Clinic from 2010 to 2019; (ii) to test whether this trend varied according to the dental health provider.

METHODS

We analysed clinic records from 2010 to 2019. Prais-Winsten analyses were performed, and the average annual percentages change (AAPC) for amalgam and composite was estimated.

RESULTS

There were 397,013 procedures, including 80,995 direct posterior restorations. Amalgam use decreased from 12.9% in 2010 to 0.5% in 2019 among students, while composite use increased from 87.1% to 99.5% of posterior restorations. The annual increase of the composite was 1.4% per year for students, while amalgam decreased by 30.2% per year on average. A similar trend was noted among the dentists.

CONCLUSIONS

A significant decrease in the use of amalgam was observed over time for both students and professionals. This trend raises questions about curriculum reviews, focusing on the repair, maintenance and safe removal of amalgam while reinforcing the learning on Minimally Invasive Dentistry and composite restorations based on the patient's caries risk.

[Quality assessment of aesthetic restorations according to FDI criteria]

The problem of hard dental tissues diseases treatment, the high need of the population to replace poor-quality restorations, as well as the constant dentistry market updating make it necessary to evaluate dental restorations using objective criteria. The purpose of this article is to present the new FDI criteria for evaluating aesthetic restorations and explanations of their use, as well as a quality comparative assessment of restorations made from various light-curing composites. The clinical part of the work was to assess the restoration quality III and IV Black classes. A total of 33 restorations were made. All patients had good oral hygiene (OHIS <0.6±0.02) was characterized by the absence of inflammation or mild inflammation of the gums (GI <0.66±0.04) and high intensity of the carious process (KPU=12.2±0.8). The analysis of the obtained data from the pilot clinical study leads to the following conclusions: new advanced FDI criteria provide complete information about quality of the restorations and can be recommended for evaluating the clinical efficacy of various materials; this evaluation system of restorations is flexible, it can change over time and it allows you to follow the new trends in materials science and restoration methods as accurately as possible.

Knowledge, Attitude, and Behavior of Restorative, Orthodontic, and Pediatric Departments' Members toward Bisphenol A Dental Exposures

AIM AND OBJECTIVES

The aim of this study is to evaluate the knowledge, attitude, and behavior of Restorative, Orthodontic, and Pediatric Dentistry Departments' members at King Abdulaziz University (KAU), Jeddah, Saudi Arabia, toward bisphenol A (BPA) dental exposure.

MATERIALS AND METHODS

A survey was pretested for face and content validity. It included ten knowledge-, four attitude-, and five behavior-based items. The collected data were analyzed using Windows SPSS software version 22 (IBM Corp., Armonk, NY, USA). Significant levels were set at 0.05.

RESULTS

A total of 109 members participated in this study. Most of them (80 [73.4]) had never attended a lecture or read an article on BPA dental exposure previously. The restorative department members showed the highest (mean ± standard deviation score) in knowledge-based questions (3.32 ± 3.323), and those who reported that they had heard of BPA previously, read an article, or attended a lecture on BPA received significantly higher mean knowledge scores (P < 0.0001). The pediatric dentistry departments' members showed significantly higher agreements to attitude questions. Only ten participants (9.2%) followed the recommended guidelines to reduce patients' exposure to BPA during the application of BPA-containing dental materials.

CONCLUSIONS

Reading an article or attending a lecture on BPA significantly improves the knowledge scores. Therefore, there is a need to increase the awareness on BPA dental exposure among different departments' members in KAU to ensure that BPA exposure to patients is minimized and to ensure the spread of this knowledge to the dental students.

Aging Reduces the Anticaries Effect of Antibacterial Adhesive - An In Vitro Biofilm Study

PURPOSE

This in vitro study investigated whether aging different restorative materials influences secondary caries development using a short-term in vitro biofilm model, hypothesizing that the antibacterial adhesive employed may lose its effect over time.

MATERIALS AND METHODS

Sixty enamel-dentin blocks were divided into 6 groups with n = 10 per group. The groups were restored with three different restorative materials, of which each sample contained an artificial gap: composite with conventional adhesive (CCA; negative control), composite with an antibacterial adhesive (CAA), and amalgam (A; positive control). Half of the groups were prepared fresh and half of the groups were submitted to an aging protocol consisting of water storage, thermocycling, storage in human saliva, and storage in 0.9% saline solution. All specimens were subjected to an intermittent 1% sucrose biofilm model for 20 days to create artificial caries lesions. Lesion progression in the enamel and dentin next to the different materials was measured as lesion depth (LD) and mineral loss (ML), using transverse wavelength independent microradiography (T-WIM). Regression analysis was used to evaluate the effect of aging on LD and ML per restorative material, corrected for gap size.

RESULTS

In the amalgam group, aging led to shallower lesions and less mineral loss. Fresh amalgam samples showed an average lesion depth of 156.65 ± 39.18 µm at wall dentin locations. Aged amalgam samples had an average lesion depth of 73.42 ± 73.50 µm. Fresh CAA samples showed lower average surface mineral loss values (9104 ± 2631 µm•vol%) than did fresh CCA samples (13166 ± 4769 µm•vol%). After aging, this effect was absent, and the average mineral loss in the CAA group was 13382 ± 5586 µm•vol%, while in the CCA group it was 15518 ± 9283 µm•vol%.

CONCLUSION

Aging can influence secondary caries development either positively or negatively depending on the kind of restorative material. Antibacterial adhesives may lose their effectiveness over time.

Curriculum time compared to clinical procedures in amalgam and composite posterior restorations in U.S. dental schools: a preliminary study

Dental clinicians have an expanding range of biomaterial choices for restoring tooth structure. Scientific developments in cariology, advances in dental biomaterials, and patients' esthetic concerns have led to a reduction in amalgam restorations and an increase in composite restorations. The aim of this study was to compare teaching time with students' clinical procedures in amalgam and composite posterior restorations in dental schools across the United States. Academic deans in 60 schools were invited to complete a survey that asked for the amount of instructional time for amalgam and composite posterior restorations and the number of clinical restorations performed by their Classes of 2009, 2010, and 2011. Of these 60, 12 returned surveys with complete data, for a 20% response rate. Responses from these schools showed little change in lecture and preclinical laboratory instruction from 2009 to 2011. There was a slight increase in two-surface restorations for both amalgam and composites; however, the total number of reported composite and amalgam restorations remained the same. Of 204,864 restorations reported, 53% were composite, and 47% were amalgam. There were twice as many multisurface large or complex amalgam restorations as composites. One-surface composite restorations exceeded amalgams. Among the participating schools, there was little to no change between curriculum time and clinical procedures. Findings from this preliminary study reflect a modest increase in two-surface resin-based restorations placed by dental students from 2009 to 2011 and little change in curricular time devoted to teaching amalgam restorations. The total number of posterior composite restorations placed by students in these schools was slightly higher than amalgams.