Journal of Research in Dental and Maxillofacial Sciences
Volume:4 Issue: 2, Spring 2019

The purpose of this study was to examine the effect of alcohol and non-alcohol mouthwashes on the color change of two types of bleach shade composite.

Twenty-two samples of IPS empress direct composite (Ivoclar Vivadent, Schaan, Liechtenstein) and 22 samples of Vitalescence snow white composite (Ultradent Products, South Jordan, UT, USA) were prepared in 10 mm diameter and 2 mm thickness. The specimens were polished with Sof-Lex (3M ESPE, USA) abrasive papers in supra fine, fine, and medium sizes. The specimens were then stored for 24 hours in distilled water at 37°C, and an initial colorimetric assay was performed using SP64 spectrophotometer. Samples were randomly divided to be placed in 20 ml of alcohol and non-alcohol Listerine mouthwashes and were incubated at 37°C for 24 hours. The color of the specimens was again measured, and color change (ΔE) was calculated. Data were analyzed using two-way analysis of variance (ANOVA) at 95% confidence level.

None of the mouthwashes caused clinically significant discoloration in the samples. The effect of both mouthwashes on composite discoloration was statistically significant (P=0.0001), and the interaction between the mouthwash and type of restorative material was significant (P=0.0001).

According to the findings of this study, alcohol mouthwashes cause more discoloration in composite resins.

The present study introduces photofunctionalization as a technique for tackling biological aging and increasing the bioactivity of titanium. This in-vitro study evaluated the effects of ultraviolet (UVC) light treatment of titanium surfaces with different time-related changes on the behavior and function of human mesenchymal stem cells (MSCs).

MSCs were cultured on nine untreated titanium surfaces (four-week-old surfaces; group 1), nine fresh UVC-treated surfaces (immediately after UV treatment; group 2), and nine three-day-old UVC-treated surfaces (group 3). Cellular proliferation and attachment were measured by MTT. Alkaline phosphatase (ALP) was assessed by total protein extraction, and the enzyme activity was evaluated using a special ALP kit. One-way analysis of variance (ANOVA) and post-hoc Tukey’s test were used to examine the effect of UVC on titanium surfaces.

The mean attachment of MSCs to titanium disks in groups 1 to 3 was 0.118±0.003, 0.103±0.007, and 0.155±0.009, respectively. The mean proliferation of MSCs in groups 1 to 3 was 0.229±0.004, 0.189±0.023, and 0.298±0.020, respectively. The proliferation and attachment in group 3 were significantly higher compared to other groups (P<0.05). Speeds of MSCs growth in groups 1 to 3 were 94%, 81%, and 92%, respectively. The ALP activity of MSCs in groups 1 to 3 was 0.153±0.003, 0.187±0.003, and 0.161±0.003, respectively. The ALP activity in group 2 was significantly higher compared to other groups (P<0.05).

UVC pretreatment of titanium surfaces increases the ALP activity. However, cellular attachment and proliferation were not increased in the present study due to the high probability of laboratory error.

Screw loosening is a common problem with both screw-retained and cemented implant restorations. It is assumed that the abutment diameter affects detorque value and screw loosening. We aimed to determine the effect of two different abutment diameters on detorque value using cyclic loading and thermocycling.

This in-vitro experimental study was conducted on sixteen Morse-taper implants (4×10 mm) with two different diameters (3.9 and 5.2 mm) installed with a 25-Ncm torque (n=8). Eight screws from each group (3.9- and 5.2-mm abutments) were maintained for a month in a stable state while the rest of the screws underwent cyclic loading for 10,000 cycles with the frequency of 1 Hz and force of 75 N/cm. Then, thermocycling was done at 5-55°C. Detorque value was determined using the torque meter used for screw tightening. Removal torque values were recorded. Maximum deformation force and fracture resistance were documented. Data were analyzed according to Student's t-test using SPSS 21.0 software.

Detorque values were 18.25±1.91 and 21.13±1.46 Ncm with 3.9- and 5.2-mm abutments, respectively. Detorque loss value was 15.50±5.83% with 5.2-mm abutment and 27±7.63% with 3.9-mm abutment. The mean difference between the two abutment diameters was 2.87±0.85 Ncm. Significant differences were observed on torque loss with 3.9-mm- compared to 5.2-mm-diameter abutments (P=0.004).

The results suggested that torque loss was lower with 5.2-mm abutment diameter.

Bacterial contamination of clinical surfaces of dental units that have been touched or been exposed to patients’ blood or saliva can be a reservoir for infections, leading to cross-contamination. This study aimed to evaluate bacterial contamination in the clinical environment of Sari Dental School in 2018.

In this cross-sectional (descriptive-analytical) study,
samples were randomly collected from 15 active dental units of five departments of Sari Dental School, including surgical, pediatrics, prosthodontics, endodontics, and restorative dentistry departments. Samples were collected from headrests, light handles, and dental seats using moist sterile swabs, and air samples were collected using agar plates. Sampling was carried out before and after dental practice. The samples were transferred to the microbiology laboratory to determine the number of various microorganism colonies. Data were analyzed using Chi-square, McNemar, and Kruskal-Wallis tests. P-values lower than 0.05 were considered significant.

A significant difference was found between the frequency of contamination before and after clinical practice based on McNemar test results. Staphylococci were more prevalent on the surfaces. Kruskal-Wallis test revealed no significant difference in the total number of microorganisms between different departments after dental practice. Bacterial contamination of air was greater than other parts, followed by dental seats.

Microbial contamination of dental units considerably increases after treatment of each patient. Therefore, disinfection of dental unit surfaces and seats between each patient is essential. Also, methods of infection control must be supervised to prevent cross-infection.

The complications of unwanted surface roughness of composite restorations are highly common due to the increasing use of this restorative material. Therefore, the present study was designed to compare the effect of four finishing and polishing (F&P) tools on surface roughness of microhybrid resin composites.

This experimental study was performed on 42 samples of CLEARFIL™ AP-X ​​microhybrid composite, which were divided into four groups of different F&P methods and one control group as follows: control (n=2), Flexi-D discs (n=10), Flexi-D + diamond polishing paste (n=10), Intensive twisted rubber polisher (n=10), and Rubber Polisher Teco (n=10). The samples were examined by profilometry. Surface roughness (Ra) of each specimen was measured at three points, and the mean value was considered as surface roughness. The results were analyzed by analysis of variance (ANOVA) and post hoc statistical tests.

The surface roughness of composite discs in an ascending order was as follows: control (0.048±0.014 µm), Flexi-D disc (0.179±0.132 µm), Intensive twisted rubber polisher (0.233±0.105 µm), Flexi-D disc with diamond polishing paste (0.232±0.141 µm), and Rubber Polisher Teco (0.251±0.087 µm; P=0.001). The difference between the two groups of Flexi-D disc with diamond polishing paste and Rubber Polisher Teco was not statistically significant (P=0.742). The level of surface roughness in Flexi-D samples was significantly lower than that of the other samples (P<0.05).

It seems that the Flexi-D disc is the best F&P tool for microhybrid resin composites.

One of the main goals of endodontic treatments is to disinfect the root canal and dentin tubules. This study compared the antimicrobial effect of different concentrations of green tea extract with that of two common irrigants on Enterococcus faecalis (E. faecalis) in the root canal system.

In this experimental study on 124 single canal teeth, suspensions derived from the 24-hour culture of E. faecalis were inoculated into the canals, and the samples were incubated for two weeks. Then, the teeth were divided into six experimental groups (n=20) and two control groups (n=2). In the first group, 5% sodium hypochlorite (NaOCl), in the second group, 2% chlorhexidine gluconate (CHX), in the third group, 3.125% green tea extract, in the fourth group, 12.5% green tea extract, in the fifth group, 25% green tea extract, and in the sixth group, normal saline was used for root canal irrigation. The next day, the extracted liquid from vortexed dentin fragments was cultured, and the colony-forming units (CFU) were counted 48 hours later. Data were analyzed using Mann-U-Whitney test.

The CFU count for NaOCl and CHX showed a statistically significant difference compared to different groups of green tea extract (P<0.001). The percentage of microorganism reduction was 100% with NaOCl, 98.9% with CHX, 58.35% with 3.125% green tea, 8.1% with 12.5% green tea, 94.8% with 25% green tea, and 57.5% with normal saline.

The results of this study showed that green tea extract can be used in endodontic treatment as the final root canal irrigant considering its naturalness and its antimicrobial ability.

Dentin dysplasia (DD) is a rare disturbance of dentin formation, characterized by normal enamel but atypical dentin formation with abnormal pulpal morphology. In DD type I, the teeth appear clinically normal in morphologic appearance and color. Radiographic analysis shows obliteration of all pulp chambers as well as short, blunted, and malformed or absent roots with multiple periapical radiolucencies involving apparently intact teeth.

We present a case of a 15-year-old girl with a developmental disturbance of dentin similar to DD type 1. Radiographic examination revealed multiple affected teeth with unique findings in accordance with DD 1d subtype. This article highlights the clinical and radiographic findings of this condition along with the differential diagnosis and management.

Management of patients with DD is difficult and requires a multidisciplinary approach. Early diagnosis of the condition is important for the initiation of effective preventive treatment.