Spectrophotometric evaluation of staining of different types of light-cure composite resins after exposure with different light-cure intensities: An in vitro study.

Context: Relation between the adequate intensity output of curing lights on color stability of composite resin is well accepted. Aims: To investigate the effect of different light-curing intensities and its relation to color stability of different polymerized composite resin materials using the spectophotometric analysis. Settings and Design: Comparative in vitro study done on composite resin discs. Subjects and Methods: A total of 180 discs comprising sixty discs prepared from three different composite resins, namely microhybrid composite resin (Filtek Z100,3M ESPE), nanohybrid composite resin (Filtek Z250 XT, 3M ESPE), and nanofilled composite resin (Filtek Z350 XT,3M ESPE) using three different light curing intensities, viz., 325-425 mW/cm2, 750-850 mW/cm2, and 1000-1100 mW/cm2. Later these discs were stained with 2% methylene blue followed by re-absorption in absolute alcohol for supernatant solution preparation which is used for the spectrophotometric analysis. Statistical Analysis Used: Spectrophotometric absorption values were analyzed using the one-way ANOVA test for intergroup analysis. Results: Mean stain absorption was the highest with nanofilled composite resin (Filtek Z350 XT,3M ESPE) after exposure with light-curing intensity of 325-425 mW/cm2 and least with microhybrid composite resin (Filtek Z100, 3M ESPE) after exposure with light-curing intensity of 750-850 mW/cm2 and this difference found was highly significant statistically (P < 0.001). Conclusions: Microhybrid composite resin (Filtek Z100, 3M ESPE) cured with intensity of 750-850 mW/cm2 showed least stain absorption indication most color stability and esthetic function.

The effect of pressure changes during simulated diving on the shear bond strength of orthodontic brackets.

INTRODUCTION: This study investigated the effect of pressure variations to which divers are subjected on shear bond strength of orthodontic brackets bonded to teeth with resin modified glass ionomer cement (RMGIC) or composite resin. METHODS: Eighty extracted premolars were randomly divided into two groups. Group 1: orthodontic brackets were bonded with RMGIC. Group 2: orthodontic brackets were bonded with composite resin. Each group was further divided into two subgroups. Subgroup A: The samples were kept at sea level pressure (101 kPa). Subgroup B: The samples were pressurised once from 101 kPa to 405 kPa for five minutes, then depressurised to 101 kPa. Shear bond strength was then measured. RESULTS: Shear bond strength of brackets bonded with RMGIC in the simulated diving group was significantly less than that of ambient pressure group (P = 0.019), while no significant difference was found between the simulated diving group and ambient pressure group for brackets bonded with resin cement (P = 0.935). At ambient pressure, there was no significant difference between shear bond strength of brackets bonded with RMGIC and composite resin (P = 0.83). In simulated diving conditions, there was a statistically significant difference between shear bond strength of brackets bonded with the RMGIC and composite (P = 0.009). CONCLUSIONS: Pressure changes during scuba diving may have an adverse effect on the retention of brackets bonded with RMGIC. Using composite resin for bonding brackets appears to be good strategy for patients such as divers who will be exposed to pressurised environments.

Evaluation of YouTube Videos as a Source of Information About Oral Self-examination to Detect Oral Cancer and Precancerous Lesions.

Objectives: The aim of this study was to investigate quality, reliability, and comprehensiveness of YouTube videos about oral self-examination to detect oral cancer and precancerous lesions and to assess whether the source, duration, quality, reliability, and/or comprehensiveness of videos influence their visibility and popularity. Materials and Methods: Videos on YouTube were searched using eight keywords similar to oral self-examination. The first 100 videos for each search term were included. Strict inclusion and exclusion criteria were adhered to, and videos were assessed for quality, reliability, and comprehensiveness. Upload date, views, likes, dislikes, duration, and source of the videos were noted. Viewing rate and interaction index were calculated for each video. Results: A total of 800 videos were analyzed, 24 of which met the inclusion criteria. Majority of videos (87%) were uploaded by the healthcare group. The visibility, quality, reliability, and comprehensiveness were higher in videos uploaded by the healthcare group when compared with the non-healthcare group, but not at a level of statistical significance. The mean interaction index score of the non-healthcare group was found to be higher than the healthcare group, with statistically significant difference. Duration of videos showed an impact on the comprehensiveness of the videos. Conclusion: There are relatively few videos on oral self-examination on YouTube, and most do not have satisfactory quality, reliability, and comprehensiveness. There is a potential to increase public awareness about oral self-examination by utilizing this tool. Videos with complete and accurate information regarding oral self-examination must be uploaded to YouTube, which is currently an important source of information for the general public.

Effect of Commonly Consumed Beverages on Microhardness of Two Types of Composites.

OBJECTIVE: The objective of the present in vitro study was to assess the influence of commonly consumed beverages on the microhardness of microhybrid and nanofilled composite resins. MATERIALS AND METHODS: Two hundred and forty cylindrical specimens were produced using circular aluminum molds of an internal diameter of 10 mm and a thickness of 2 mm, 120 samples each from microhybrid composite (Filtek Z250, 3M, ESPE, USA) and nanofilled composite (filtek Z250, 3M, ESPE, USA). They were divided into 4 subgroups of 30 specimens each. These specimens were immersed in distilled water, tea, coffee, and cola drink, respectively. Microhardness was calculated using Vickers microhardness tester (MMT-X7 Matsuzawa, Japan). Data were statistically analyzed using paired t-test and one-way analysis of variance (ANOVA) using Tukey's correction was used for multiple subgroup comparison. RESULTS: Microhardness of both the composites reduced after immersing in different beverages compared to water. Nanofilled composites showed more change in microhardness than microhybrid composite. Cola caused a significant reduction in microhardness followed by coffee, tea, and water. CONCLUSION: The beverages used have negative effects on the hardness of both the type of composites. The surface microhardness of nanofilled composite is significantly reduced when immersed in carbonated beverages like cola. HOW TO CITE THIS ARTICLE: Barve D, Dave PN, Gulve MN, et al. Effect of Commonly Consumed Beverages on Microhardness of Two Types of Composites. Int J Clin Pediatr Dent 2020;13(6):663-667.

Microcomputed tomographic evaluation of shaping ability of two thermo mechanically treated single-file systems in severely curved roots.

CONTEXT: Canal shaping abilities such as canal transportation, centering ability, and preparation time are important and have to be considered before using any Nickel-Titanium file system. AIM: This in vitro study aimed to evaluate and compare the amount of canal transportation, centering ability, and time required for the shaping of severely curved canals with WaveOne Gold (WOG) Primary Reciprocating file and One Curve (OC) Rotary file using the micro computed tomography (µCT). MATERIALS AND METHODS: Thirty intact mesial roots of extracted human mandibular first molars having severe curvature (25°-35°) were selected. Samples were divided into two groups. Samples in Group I and II were shaped with WOG primary reciprocating files and OC rotary files, respectively, to the working length. Time required to prepare each canal was recorded. µCT pre- and post-instrumentation scans of all samples were taken. The cross-sectional images at 3, 6, and 9 mm from the radiographic apex were selected for analysis. Statistical analysis was performed using the Kruskal-Wallis and unpaired t-test. RESULTS: At 3 mm, OC showed statistically lower canal transportation with mean value (0.17 ± 0.10) than WOG (0.55 ± 0.42). Furthermore, OC showed statistically significant better centering ability (0.59 ± 0.25) than WOG (0.39 ± 0.20) at 3 mm level. However, the differences between both instruments were not statistical significant at 6 and 9 mm level for canal transportation and centering ratio. WOG reciprocating file required less time for canal preparation than OC file. CONCLUSIONS: OC rotary file showed less canal transportation and better canal centring ability than WOG file, during the preparation of severely curved canals. However, WOG required less time for canal preparation.

Management of Horizontal Root Fracture in the Middle Third via Intraradicular Splinting Using a Fiber Post.

Radicular fractures in permanent teeth are uncommon injuries and account for only 0.5-7% of dental traumas. These fractures commonly result from a horizontal impact and are transverse to oblique in direction. Their incidence is more in the middle third of the root than at the apical and cervical thirds. This paper describes a case of complicated crown fracture of maxillary incisors along with horizontal root fracture at the middle third of maxillary right central and lateral incisor. The fractured root fragments of the upper right central and lateral incisor were united with the help of a glass fiber post after receiving an endodontic treatment. The other two incisors were treated endodontically followed by post endodontic restorations. Eventually the four incisors were restored with porcelain fused to metal crowns. A one-year follow-up revealed a well stabilized assembly of the root fragments and the post.

The effect of environmental pressure changes on the retentive strength of cements for orthodontic bands.

OBJECTIVES: The purpose of this study was to evaluate the effect of environmental pressure changes on the retentive strength of orthodontic bands cemented with conventional glass ionomer cement or resin-modified glass ionomer cement. MATERIALS AND METHODS: Stainless steel bands were cemented to 80 extracted first and second molars in two equal groups comprising conventional glass ionomer cement and resin-modified glass ionomer cement. Each group was randomly divided into two sub-groups of 20 samples each, one sub-group to act as a control, and the other to be used experimentally. After seven days of storage, the experimental groups were subjected to simulated dives to 405 kPa [corrected] for 3 minutes, 15 times in a pressure pot, after which the force required to deband was tested using a universal testing machine. The data were statistically analysed using Student's t-tests, significance being assumed at P < 0.001. RESULTS: The retentive strength of bands cemented with conventional glass ionomer in the pressure-cycled group was statistically significantly less than that in the control group. No statistically significant difference in strength was found between the two groups cemented with resin-modified glass ionomer. CONCLUSIONS: This study showed that the retentive strength of bands cemented with conventional glass ionomer is reduced after pressure cycling. We suggest that dentists should consider using resin-modified glass ionomer cement for cementing orthodontic bands for patients who are divers and thus likely to be exposed to raised-pressure cycling.