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Resin composites have various applications. At the same time, they have some drawbacks, such as polymerization shrinkage. Conventional composites are polymerized in 2-mm thick layers. However, in posterior restoration, the 2-mm depth of cure is not satisfactory. To find a solution, resin composites have been vastly improved in terms of fillers, matrix and initiators.To evaluate polymerization properties and physical characteristics of fiber-reinforced composites and compare them with bulk-fill composites that are designed for large posterior restorations.Samples were prepared from each resin composite. The 3-point bending test was performed to evaluate the flexural strength of all composites. The depth of cure of the composite from 1 mm to 4 mm of depth was analyzed using Vickers hardness test (VHN). To analyze the degree of conversion, Fourier-transform infrared spectroscopy (FTIR) of the top and bottom surfaces of the samples with 4-mm thickness was calculated. The data were analyzed using one-way analysis of variance (ANOVA) test followed by post hoc test (95% confidence interval (95% CI)).The Filtek showed the highest flexural strength followed by everX and X-tra fil. At 1-mm depth, X-tra fil had the highest and Gradia had the lowest microhardness. At the 4-mm depth, the microhardness trend was as follows: everXFiltekX-tra filGradiaBeautifil. The everX composite had the lowest reduction of the degree of conversion at 4-mm thickness, which showed a significant difference in comparison with Filtek, Gradia and X-tra fil composites.Based on the results of our study, it can be concluded that the fiber-reinforced composite everX showed more favorable results regarding polymerization properties, such as the degree of conversion and the depth of cure. However, the flexural strength results in Filtek were better than those in everX.

Antibacterial photodynamic therapy (aPDT) has drawn increasing attention as a noninvasive approach to remove bacterial contaminants such as E. faecalis from the tooth surface. In this study, curcumin (CUR) was loaded into ZSM-5 zeolite and the prepared photosensitizers (CUR@ZSM) were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet–visible spectroscopy (UV–Vis). The loading efficiency, and release behavior of CUR were studied in CUR@ZSM. The antimicrobial and anti-biofilm potential of the photosensitizer were evaluated against E. faecalis via colony forming unit and crystal violet assays, respectively. No significant changes were observed in the size, morphology and crystallinity of the zeolite after CUR loading. CUR@ZSM showed a significant photodynamic inactivation effect through complete bacterial elimination and reduced the biofilm formation ability of E. faecalis up to about 80%. The results revealed that CUR@ZSM could be considered as a new potential photosensitizer for further study against endodontic infections.

Antimicrobial photodynamic therapy (aPDT) is a high potential strategy for the treatment of microbial infections in endodontics. In this study, a novel antibacterial agent was designed and prepared based on the two morphologies of zinc oxide nanomaterials (NMs) as ZnO nanosphere (ZnOS) and ZnO nanorod (ZnOR). Their surfaces were coated with carnosine (CAR)-functionalized polycyclodextrin (ZnO@PCD-CAR) for higher payload of curcumin (CUR) as a photosensitizer (PS). This system was characterized using FT-IR, XRD, TGA, FE-SEM, zeta potential analysis and UV-visible spectroscopy. The colony forming unit (CFU) assay was carried out to evaluate the antimicrobial properties of the nanoformulations againts Enterococcus faecalis (E. Faecalis). The target products (ZnOS@PCD-CAR/CUR and ZnOR@PCD-CAR/CUR) exhibited a light stability approximately by 2.9 and 2.8 fold, respectively, higher than the free CUR. Compared to the bare CUR, these materials indicated more stability againts pH variations. ZnOS@PCD-CAR/CUR and ZnOR@PCD-CAR/CUR NMs-mediated aPDT, significantly declined the count of E. Faecalis strains about 1.5 and 2 log (P < 0.05). Due to the high CUR loading, proper stability and significant inhibitory effects against E. Faecalis, ZnO@PCD-CAR/CUR could be considered as a promising antimicrobial agent in aPDT for efficient treatment of root canal infections.

Introduction: Due to the increasing prevalence and high mortality rate of oral squamous cell carcinoma (OSCC) and problems with its routine treatments, more recent modalities like photodynamic therapy (PDT) have been developed. PDT effectively destroys tumor cells with minimum side effects. Research on in vitro effects of PDT may be helpful in determining the molecular mechanisms responsible for its effectiveness and can lead to the development of more efficient techniques. The aim of this study was to review the use of PDT in OSCC among in vitro studies. Methods: A literature search for English articles on PDT in OSCC was performed in PubMed, Scopus, Google Scholar, and Web of Science. Data were extracted based on the inclusion/exclusion criteria, which were detailed using the PICO framework: all eligible in vitro studies evaluating the effects of PDT on the viability of OSCC compared to controls without PDT were included. Results: Forty-one out of 567 studies were selected. The tongue was the most common OSCC site, 5-aminolevulinic acid was the most used photosensitizer (PS), cell viability/toxicity and apoptosis were the most evaluated outcomes, and lasers with wavelengths of 600-700 nm were the most common light sources and wavelengths respectively. Conclusion: PDT showed promising effects on reducing the viability of OSCC cells. Cell lines from various sources or even those originating from the same location sometimes responded differently to the same protocol. Considering the favorable results obtained from natural PSs and regarding their additional health-promoting properties, their use in future investigations with different cell lines and light specifications is recommended.

Photobiomodulation is recognized as an effective method for adjunct therapy in periodontal treatments. Our purpose in this study was to investigate the effects of different energy densities of 915 nm diode laser on the viability and viability capacity of human gingival fibroblast cells. Cell samples were examined in five groups, including four irradiation groups with low-level diode laser 915 nm, 1, 2, 3, 4 J cm

Background and Aim: Considering the importance of the clinical significance of the elongated styloid process, this study aimed to assess the prevalence and pattern of calcification and elongation of the styloid process on digital panoramic radiographs of an Iranian population. Materials and Methods: This study was conducted on 500 digital panoramic radiographs of patients over 18 years old with visible styloid processes. The length of styloid processes was measured by software, and the length>30mm was considered as elongated. Prevalence and pattern of elongation and calcification were determined according to the classification proposed by Langlais. The associations of age, sex, and the jaw side of elongation was determined using generalized estimating equations with exchangeable matrix and binary logistic model. Results: Elongation of styloid process was observed in 177 (17.7%) of 1000 evaluated processes were elongated. The Type I pattern of elongation (n=80, 45%) and type A pattern of calcification (n=69, 39%) had the highest frequency. Although the prevalence of elongation seemed to be higher in males, the difference was not significant (P=0.11). No significant association was observed between the side of jaw and elongation (P=0.54). Elongation was more common in the 40-59-year-old group compared to

The aim of this study was to evaluate the effect of neodymium:yttrium–aluminum–garnet (Nd:YAG) laser irradiation before adhesive application on microtensile bond strength of resin composite to dentin surface. Materials and methods: in this experiment, 40 human extracted third molar teeth were chosen and the occlusal surface was cut to achieve a flat dentin surface. Groups were divided based on the adhesives (G-Premio Bond or Clearfil S3 Bond) and the presence or absence of Nd:YAG laser application. All the samples were restored with resin composite and subjected to a universal testing machine for a microtensile bond strength test. Fracture mode for each failure was analyzed under the stereomicroscope. According to the results, there was a significant difference between the two adhesives with Nd:YAG laser irradiation. The application of laser enhanced the microtensile bond strength in both adhesives. In all groups, regardless of laser application, adhesive failure was dominant between fracture patterns. It was concluded that Nd:YAG laser irradiation on dentin surface prior to adhesive application has a positive effect and significantly increases the microtensile bond strength of restoration to the tooth.

The aim of this study was to determine the pulp chamber temperature changes during bleaching procedures with irradiation from 445 nm and 970 nm diode lasers at different powers. A total of 120 human maxillary central incisors were used for this study. Diode lasers at two different wavelengths were irradiated in this evaluation: 970 nm at 1.5 W of power, 970 nm at 2 W, 445 nm at 1 W and 445 nm at 1.5 W. A thermometer was inserted into the pulp chamber and the temperature increase after bleaching was recorded. The results indicated that there was not a significant difference between the groups at the same wavelengths (P > 0.05). However, there was a significant difference between groups at different wavelengths (P < 0.05). The highest recorded pulp temperature increase was for the 970 nm diode laser with 2 W of power (2.0 ± 0.5), and the lowest pulp temperature rise was 0.1 ± 0.2 for the 445 nm diode laser with 1 W of power. According to the results of this study it can be concluded that the temperature elevation after bleaching with the diode laser at the wavelengths 970 nm and 445 nm is in the safe range, and both wavelengths with the parameters applied in this study can be used as prudent in-office bleaching techniques.

Background This study aimed to investigate the penetration depth of two different dyes after root canal preparation using PIPS and SWEEPS methods. Materials and methods A total of 60 single-rooted human teeth which were extracted for periodontal reasons were collected and stored in the sterile saline until using in the study. The crowns of the teeth were cut such that the remaining piece was 12 mm long. The root canals were prepared. Teeth were divided randomly into two initial groups (n = 30): indocyanine green solution (ICG) and methylene blue solution. Then, these teeth were divided into final subgroups (n = 10): Er:YAG laser irradiation with PIPS(photon-induced photoacoustic streaming) technique, Er:YAG laser irradiation with SWEEPS(shock-wave enhanced emission photoacoustic streaming) technique, and no irradiation. The penetration depth measurements were done by the stereo microscope in three zones of each specimen. Results The difference between ICG in the control group and PIPS and SWEEPS in the coronal area was not significant. In the middle section the difference between PIPS and the control group was marginally insignificant (P = 0.053). In the methylene blue group, PIPS had significantly higher penetration depth in the apical area compared to the control group (P = 0.004). In the middle section, both PIPS and SWEEPS showed significantly higher penetration than the control group. Conclusion According to the results of this study, the laser has the potential to increase the penetration of methylene blue. Root canal preparation with the PIPS technique can increase the dye penetration. However, the SWEEPS technique and the conventional method have a similar outcome in terms of dye penetration.

Background and Aim: Discoloration is a major concern with regard to the use of tooth-colored restorations. Type of restorative material and surface treatment are believed to play a role in this regard. This study sought to compare the color change of glazed and polished dental porcelain after 30 days of immersion in chlorhexidine (CHX). Materials and Methods: In this in vitro, experimental study, 20 discs with 10 mm diameter and 2 mm thickness were fabricated of A1 shade of Noritake porcelain using a gypsum mold. All samples had one opaque layer. They were then randomly divided into two groups of 10. Glaze powder was added to porcelain in group 1, and group 2 was polished using a polishing kit. The CIE L*a*b color parameters of samples were then measured using a spectrophotometer. All samples were immersed in 0.02% chlorhexidine solution for 30 days and color parameters were then measured again. Change in each color parameter was compared between the two groups (polished and glazed) using t-test. Results: After 30 days of immersion in CHX, ∆E was 0.76±0.16 in the glazed and 0.89±0.16 in the polished group. The difference in this regard between the two groups was not significant (P=0.092). Conclusion: Both polishing and glazing confer optimal color stability to dental porcelain.

Background The appearance of the teeth is of great importance to patients, particularly tooth color. In recent years, tooth whitening has been one of the most popular ways to restore tooth color. Bleaching gels can be affected by heat, light or laser, which can improve its effects. This study intends to examine the effects of two different wavelengths of diode laser (445 & 915 nm) after the bleaching process, on the enamel micro-hardness. Methods A total of 65 caries-free humans third molars were randomly divided into five groups (N = 13): first group: bleaching gel activated with 915 nm diode laser (1.5 W), second: bleaching gel activated with 915-nm (2.5 W), third: bleaching gel activated with 445-nm (1 W), fourth: bleaching gel activated with 445-nm (1.5 W), fifth (control group): bleaching gel without laser activation. Micro-hardness test (Vickers test) was performed before and after the treatment. The data were submitted to repeated measurement ANOVA and Tukey's HSD post hoc test (α = 0.05). Results Enamel micro-hardness did not change significantly in groups 3 and 4 but decreased in groups 1 and 2. Group 2 showed the most reduction in micro-hardness. There were no significant changes in the control group. Conclusion According to the results of this study, 445 nm Diode laser did not reduce enamel micro-hardness, making it suitable for bleaching treatments. However, more studies are required to consider other factors, such as color changes and pulp temperature.

Introduction : T Laser irradiation of dentin surface can affect its surface topography and roughness. Atomic force microscopy (AFM) is among the most efficient tools for determination of surface topography of natural biomolecules in nano-scales. Surface roughness affects plaque retention especially in the cervical region. This study aimed to assess and compare the obstruction of dentinal tubules and dentin surface roughness after irradiation of erbium: yttrium aluminum garnet (Er:YAG )and CO2 lasers for treatment of dentin hypersensitivity (DH) . Methods : Five disc-shaped samples measuring 3 mm in thickness were fabricated by horizontal sectioning of the cervical area of five extracted human molars using a low speed saw. Each disc was divided into 3 segments by a bur under water coolant. The three segments of each disc were placed on a glass slide. First segment: No intervention (control group). Second segment: Er:YAG laser irradiation (2940 nm, 50 mJ, 10 Hz and 0.5 W, 30 seconds) along with water coolant. Third segment: CO2 laser irradiation (10600 nm, 80 Hz, 0.3 W, 30 seconds) along with water coolant. After that, the surfaces underwent non-contact AFM. The diameters of dentinal tubules as well as surface roughness were then measured and statistically analyzed using repeated measures ANOVA. Results : The surface roughness parameters (Ra, Rq) showed increased roughness after laser irradiation and this increase in roughness after Er:YAG laser application was significant compared to the control group (P = 0.048). However, CO2 laser caused no significant change in surface roughness. Also, after Er:YAG laser application, fewer open dentinal tubules were observed and the remaining open tubules had a smaller diameter. Conclusion : Based on the results, Er:YAG laser irradiation obstructs the dentinal tubules and increases the dentin surface roughness. This increase in surface roughness can cause microbial plaque retention and increase the risk of caries and periodontal disease. Application of CO2 laser (compared to Er:YAG) lead to slight but clinically significant obstruction of dentinal tubules and surface roughness