Resorbable Membranes for Guided Bone Regeneration: Critical Features, Potentials, and Limitations.

Lack of horizontal and vertical bone at the site of an implant can lead to significant clinical problems that need to be addressed before implant treatment can take place. Guided bone regeneration (GBR) is a commonly used surgical procedure that employs a barrier membrane to encourage the growth of new bone tissue in areas where bone has been lost due to injury or disease. It is a promising approach to achieve desired repair in bone tissue and is widely accepted and used in approximately 40% of patients with bone defects. In this Review, we provide a comprehensive examination of recent advances in resorbable membranes for GBR including natural materials such as chitosan, collagen, silk fibroin, along with synthetic materials such as polyglycolic acid (PGA), polycaprolactone (PCL), polyethylene glycol (PEG), and their copolymers. In addition, the properties of these materials including foreign body reaction, mechanical stability, antibacterial property, and growth factor delivery performance will be compared and discussed. Finally, future directions for resorbable membrane development and potential clinical applications will be highlighted.

Efficacy of synthesized cubic spirulina platensis photosensitizer in anticancer photodynamic therapy: An in vitro study.

Photodynamic therapy (PDT) is an option in select cancer management. Photosensitizers derived from natural sources can offer additional health benefits and play a crucial role in enhancing the efficacy of PDT in cancer treatment. We herein synthesized a cubic form of spirulina platensis (SP) and compared its anticancer-PDT efficacy with the naturally-occurring microhelical SP (MSP) and phycocyanin (Pc) against a tongue cancer cell-line and fibroblast cells. Cubic SP (CSP) was synthesized and characterized using standard analyses. CAL-27 and HGF cell-lines were incubated at different concentrations with each photosensitizer and were irradiated with 635 nm diode-laser. The viability, cellular-uptake, apoptosis and oxidative stress potential were quantitatively analyzed and statistically compared at P<0.05. Our results demonstrated that all three photosensitizers were non-toxic to normal cells before laser irradiation. In CAL-27, viability significantly decreased after PDT in all photosensitizer groups (P<0.05). Whereas, in HGF, Pc exhibited phototoxicity after laser irradiation (P=0.032). Cell-death was mainly apoptotic in Pc and CSP, but necrotic in MSP. Cellular-uptake was significantly higher in Pc, but was similar in MSP and CSP. Increase in reactive oxygen species was significantly higher in the Pc group compared to both SPs (P<0.05). We concluded that both SPs were safe and efficient photosensitizers for anticancer-PDT. CSP exhibited predominant and significant apoptotic death in CAL-27 and HGF cell-lines, while MSP mainly induced necrotic cell death. Despite the good photosensitizing performance of Pc, its use in higher concentrations should be considered with caution, due to the reduced viability that occurred following its use in PDT.

Evaluation of One- and Two-Step Impression Techniques and Vertical Marginal Misfit in Fixed Prothesis.

Methods: 12 impressions were made of a resin maxillary model (second premolar and second molar) with two prepared abutment teeth using vinyl polysiloxane (VPS); the margin of the second premolar was 0.5 mm subgingivally; and the margin of the second molar tooth was at the level of the gingiva. Impressions were made using two techniques: one-step and two-step putty/light materials. A three-unit metal framework was fabricated on the master model using the computer-aided design/computer-aided manufacturing (CAD/CAM) technique. The vertical marginal misfit was evaluated in the buccal, lingual, and mesial and distal surfaces of the abutments on the gypsum casts using a light microscope. Data were analyzed using the independent t-test (α < 0.05). Results: The results showed significantly lower vertical marginal misfit in all six areas evaluated around the two abutments in the two-step impression technique compared with the corresponding values in the one-step technique. Conclusion: Vertical marginal misfit in the two-step technique with a preliminary putty impression was significantly lower than in the one-step putty/light-body technique.

Color Stability of Different Denture Teeth Following Immersion in Staining Solutions.

Objectives: This study aimed to assess the color change (∆E00) of 7 brands of denture teeth (conventional acrylic and composite teeth) following immersion in staining solutions. Materials and Methods: Maxillary central incisor denture teeth made of 4 conventional acrylic resins (Vitapan, SR Vivodent PE, Beta Star and Crystal) and 3 composite resins (Finex, Emeral and Phonares II) were randomly divided into four groups (n=5). Denture teeth of different brands were immersed in tea, coffee, cola, and turmeric solutions. The solutions were incubated at 37°C. The baseline color of the teeth was measured using an intraoral spectrophotometer. The color of the teeth was measured after 24 h (∆E12), 1 week (∆E13), 2 weeks (∆E14), and 1 month (∆E15). ∆E00 was calculated and analyzed using one-way ANOVA. Pairwise comparisons were performed by the Tukey's post-hoc test (P<0.05). Results: The color stability of all teeth was significantly affected by the solutions (P<0.001). The type of tooth and coloring solution had significant interactions at all times (P<0.05). Turmeric caused the maximum color change in all teeth after 1 month. Repeated measures ANOVA showed that ∆E00 of all teeth was significantly affected by the duration of immersion in the solutions (P<0.001). Conclusion: within the limitations of this study, 1-month immersion of denture teeth in coffee, tea and cola solution altered the ∆E values; however, they were within the acceptable range, except for Beta Star. Turmeric solution caused unacceptable color change in all denture teeth even after 24 h of immersion.

Comparative Evaluation of Microtensile Bond Strength of Three Adhesive Systems.

Objectives: The aim of this study was to assess the microtensile bond strength of three universal adhesives to dentin and enamel. Materials and Methods: Sixty extracted human third molar teeth were chosen and divided into six groups regarding the adhesive (G-Premio Bond, Clearfil S3 Bond or Single Bond) and tooth surface. All the applied bonding agents were universal adhesives. The teeth were polished and the adhesives were applied; then the teeth were restored with composite resin. The samples were mounted in acrylic resin and sectioned. The specimens were subjected to a universal testing machine and the microtensile bond strength was measured. The failure mode of each specimen was determined under a stereomicroscope. Data were analyzed using two-way ANOVA (α=0.05). Results: The microtensile bond strength of G-Premio Bond to enamel and dentin was 11.79±8.27 and 17.55±9.47 MPa, respectively which was not significantly different from the values in Single Bond group (15.59±10.66 and 17.19±10.09 MPa to enamel and dentin, respectively; P>0.05). However, the values for Clearfil S3 Bond were 7.11±4.23 and 7.88±8.83 MPa to enamel and dentin, respectively, which were significantly lower than the values for G-Premio Bond (P<0.05). Scanning electron microscopic (SEM) images showed that the adhesive failure was dominant in both enamel and dentin groups and in all adhesive systems. Conclusion: G-Premio Bond and Single Bond provided higher microtensile bond strength compared with Clearfil S3 Bond. Universal adhesives with their acceptable performance can be applied in self-etch mode on both enamel and dentin.

Comparative evaluation of fiber-reinforced, bulk-fill and conventional dental composites: Physical characteristics and polymerization properties.

BACKGROUND: 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. OBJECTIVES: 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. MATERIAL AND METHODS: 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)). RESULTS: 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: everX > Filtek > X-tra fil > Gradia > Beautifil. 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. CONCLUSIONS: 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.

In Vitro Anti-tumor Effects of Photodynamic Therapy on Oral Squamous Cell Carcinoma: A Review.

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.

The effect of photodynamic therapy on head and neck squamous cell carcinoma cell lines using spirulina platensis with different laser energy densities.

BACKGROUND: Considering the anti-cancer properties of spirulina platensis (S. platensis), we aimed to investigate the effectiveness of this algae as a novel natural photosensitizer for photodynamic therapy (PDT) against oral and hypopharyngeal cancer cells. The appropriate laser energy density to apply during PDT was also determined. METHODS AND MATERIALS: CAL-27, FaDu and HGF cell lines were exposed to S. platensis with concentrations of 0.3 g/l and 0.6 g/l and were irradiated with 635 nm diode laser using 2, 4, 12, and 24 J/cm2 energy densities with constant power. MTT assay was performed to investigate cell viability and cytotoxicity after 24 h. The results were analyzed using two-way ANOVA and post hoc Tukey tests (P-value<0.05). RESULTS: survival rate in CAL-27 (P-Value<0.001) and FaDu (P-Value<0.001) cell lines were significantly different following irradiation with various laser energy densities. Different concentrations of S. platensis had no significant effect on the viability of CAL-27 cells (P-Value=0.158) and FaDu cells (P-Value=0.072) and showed no significant cytotoxicity against HGF cells, with or without laser. CONCLUSION: S. platensis could be considered as a novel safe and effective natural photosensitizer for cancer PDT with no cytotoxic effect on normal cells. When combined with laser using appropriate energy densities, it has the ability to induce death in oral and hypopharyngeal cancer cell lines.

A modified TEGDMA-based resin infiltrant using polyurethane acrylate oligomer and remineralising nano-fillers with improved physical properties and remineralisation potential.

OBJECTIVES: This study aimed to modify an experimental triethylene glycol dimethacrylate (TEGDMA) based resin infiltrant using PUA oligomer and two remineralising fillers, including fluorohydroxyapatite (FHA) and fluoride-doped bioactive glass (FD-BG), to improve the mechanical and physical properties and induce remineralising potential. MATERIALS AND METHODS: The polyurethane acrylate oligomer (PUA) was synthesised and characterised. Experimental resin infiltrant was prepared by mixing 10% of synthesised PUA with 88% TEGDMA. Water contact angle, penetration coefficient, and penetration depth were then measured. The FHA and FD-BG fillers were synthesised and characterised. To prepare nano-filled resin infiltrant, 5% of each powder was mixed with the prepared resin infiltrant. The prepared resin infiltrants were characterised to evaluate their degree of conversion, mechanical properties, water sorption, and solubility. The ion release of filled resin was also assessed. The non-infiltrated and infiltrated enamel specimens underwent fourteen days of pH-cycling, and a surface microhardness was done to assess the resistance to demineralisation. RESULTS: The results showed that the addition of PUA to TEGDMA increased the mechanical properties and decreased water sorption and solubility. The addition of synthesised FD-BG fillers to resin infiltrant significantly improved the resistance to demineralisation of enamel samples compared with other groups (p ≤ 0.001). The FHA fillers also improved the resistance to demineralisation; however, the produced changes were not statistically meaningful (p > 0.05). CONCLUSIONS: Based on the results, the PUA+TEGDMA+ FD-BG/FHA composite can be used as an alternative material for pure TEGDMA in enamel infiltration approaches owing to its better mechanical properties, lower water sorption and solubility, and also remineralisation potential. CLINICAL SIGNIFICANCE: A resin infiltrant with remineralisation potential, lower water sorption and solubility and higher mechanical properties may enhance the management of early caries lesions.

Fabrication of bioactive glass coating on pure titanium by sol-dip method: Dental applications.

This study aimed to assess the mechanical and biological properties of bioactive glass (BG) coating on titanium (Ti). Bioinert Ti substrates were coated by BG to induce bioactivity to the surface. The sol-gel derived BG 58S sol was successfully prepared and coated on the abraded and blasted Ti surface using the sol-dip method. The characterization and cell study for all substrates' surface was carried out. Adhesion test confirmed that a firmly adhered BG coating layer was formed on the abraded and blasted Ti. The measured bonding strength between the coating and the blasted Ti substrate was the highest among all samples, which was 41.03±2.31 MPa. In-vitro cell viability and alkaline phosphatase activity (ALP) tests results also showed that BG coating on the Ti substrate improved the biological properties of the surface. The BG sol-dip coating method could be used to fabricate Ti substrate with a bioactive surface.

Physical and mechanical characteristics of short fiber-reinforced resin composite in comparison with bulk-fill composites.

PURPOSE: The objective of this study was to evaluate the physical and mechanical properties of a short fiber-reinforced resin composite: everX-Posterior and compare it with two bulk-fill composites, namely, Filtek Bulk-fill and Beautifil-Bulk, which are intended for large posterior restorations. METHODS: Investigated properties were flexural strength, flexural modulus, surface roughness, volumetric shrinkage and depth of cure. Scanning electron microscopy images of each specimen after the flexural test were used for cross-sectional comparison. Results were analyzed using ANOVA following Tukey post-hoc test. RESULTS: Flexural strength of everX-Posterior was comparable with two other resin composites, showing higher flexural modulus. EverX-Posterior showed the highest surface roughness after polishing and the lowest volumetric shrinkage (2.29%) among all composites used in this study. Data also showed that the everX-Posterior depth of cure was 4.24 mm, which was the highest among the three groups. CONCLUSION: Based on the results of this study, it was concluded that everX-Posterior as a short fiber-reinforced composite showed improvements and satisfactory performance in mechanical and physical properties, which make it a reliable base material candidate for large posterior restorations.

Effect of Volume and Renewal of the Storage Media on the Release of Monomer from Dental Composites.

This study evaluated the effect of the volume and renewing of storage media on monomer leachability from dental composite. Samples of two dental composites (BEAUTIFIL II Gingiva (BG) and Filtek Bulk-Fill Flowable (FBF)) were stored after polymerization in 1 and 3 milt storage media (ethanol/water 75%) for seven days. Refreshing of storage media was done in half of the samples of each group. The amounts of releasing monomers (UDMA, BisGMA, TEGDMA) in storage media were measured by high-performance liquid chromatography (HPLC). Data was analyzed using two-way ANOVA and t-test (α = 0.05). Elution of TEGDMA and UDMA from both composites was significantly higher in 3 mL storage media. In groups with refreshing of storage media, BisGMA had higher amounts of release. Saturation makes the storage media volume important factor in monomer elution. Refreshing of storage media had significant effect on monomer release before the elution of 50% of total released monomer.

Optimization of antimicrobial efficiency of silver nanoparticles against three oral microorganisms in irreversible hydrocolloid impressions.

BACKGROUND AND OBJECTIVES: Silver nanoparticles (Ag-NPs) are potent antimicrobial agents, which have recently been used in dentistry. The aim of the current study was to optimize antimicrobial activity of Ag-NPs used in preparing irreversible hydrocolloid impressions against three microorganisms of Escherichia coli, Streptococcus mutans and Candida albicans. MATERIALS AND METHODS: After assessing antimicrobial activity of the compound using disk diffusion method, three parameters of concentration of Ag-NPs (250-1000 ppm), ratio of hydrocolloid impression material powder to water (0.30-0.50) and time of mixing (20.0-60.0 s), affecting antimicrobial activity of irreversible hydrocolloid impression materials against the three microorganisms, were optimized. This combined process was successfully modeled and optimized using Box-Behnken design with response surface methodology (RSM). Decreases in colony number of E. coli, S. mutans and C. albicans were proposed as responses. RESULTS: Qualitative antimicrobial assessments respectively showed average zone of inhibition (ZOI) of 3.7 mm for E. coli, 3.5 mm for S. mutans and 4 mm for C. albicans. For all responses, when the mixing duration and powder-to-water ratio increased, the circumstances (mixing duration of 59.38 s, powder-to-water ratio of 0.4 and Ag-NP concentration of 992 response) increased. Results showed that in optimum ppm, the proportion of decreases in colony numbers was maximum (89.03% for E. coli, 87.08% for S. mutans and 74.54% for C. albicans). Regression analysis illustrated a good fit of the experimental data to the predicted model as high correlation coefficients validated that the predicted model was well fitted with data. Values of R2Adj with R2Pred were associated to the accuracy of this model in all responses. CONCLUSION: Disinfection efficiency dramatically increased with increasing of Ag-NP concentration, powder-to-water ratio and mixing time.

The effect of laser-activated bleaching with 445 nm and 915 nm diode lasers on enamel micro-hardness; an in vitro study.

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.

Insulin within the Arcuate Nucleus Has Paradoxical Effects on Nociception in Healthy and Diabetic Rats.

INTRODUCTION: Broad neural circuits originate from the hypothalamic arcuate nucleus and project to many parts of the brain which are related to pain perception. Insulin receptors are found in the arcuate nucleus. Since nociception may be affected in type 1 diabetes, the present study aimed to investigate the intra-arcuate nucleus insulin role in pain perception in streptozotocin (STZ)-induced diabetic and healthy rats. METHODS: Regular insulin was microinjected within the arcuate nucleus and the pain tolerance was measured using the hot plate and the tail-flick apparatus in diabetic rats. RESULTS: The results showed that the arcuate nucleus suppression with lidocaine could increase thermal nociception in non-diabetic animals. Also, insulin within the arcuate nucleus decreased the acute thermal pain perception in these animals. STZ-induced diabetes produced hypoalgesia which the latency of these tests, progressively increased over time after induction of diabetes. Also, in the same animal group, intra-arcuate injection of insulin reduced the latency of nociception. CONCLUSION: Intra-arcuate insulin has paradoxical and controversial effects in healthy and diabetic rats' nociception. These effects seem to be due to the insulin effect on releasing proopiomelanocortin and its derivatives.

Antibacterial and Antibiofilm Efficacy of Antimicrobial Photodynamic Therapy Against Intracanal Enterococcus faecalis: An In Vitro Comparative Study with Traditional Endodontic Irrigation Solutions.

OBJECTIVES: Enterococcus faecalis (E. faecalis), an infecting microorganism of the root canals, is difficult to eliminate during endodontic therapy. In this study, the effect of root canal disinfection with sodium hypochlorite (NaOCl) and chlorhexidine (CHX) was evaluated on planktonic and biofilm forms of E. faecalis in comparison with antimicrobial photodynamic therapy (aPDT) as an alternative strategy for root canal disinfection. MATERIALS AND METHODS: In this study, E. faecalis (ATCC 29212) was used. The experimental procedures included aPDT with curcumin (CUR) and indocyanine green (ICG) as photosensitizers, irrigation with 5.25% NaOCl, 0.2% and 2.0% CHX solutions as traditional endodontic irrigating solutions, and the control group. The antibacterial and anti-biofilm potentials were assessed by counting the colony forming units and also using the crystal violet assay, respectively. RESULTS: According to the results, E. faecalis biofilm was disrupted by 65.3%, 81.0% and 92.6% using 0.2% CHX, 2.0% CHX, and 5.25% NaOCl, respectively (P<0.05). In addition, CUR- and ICG-mediated aPDT displayed a significant reduction in E. faecalis count (90.2% and 82.5%, respectively) and its biofilm (83.6% and 75.2%, respectively) in comparison to the control group (P<0.05). CONCLUSIONS: APDT has a high potential for elimination of E. faecalis and is almost equivalent to NaOCl and CHX. It can be used as an adjucnt to conventional endodontic irrigating solutions.

The effect of sublethal photodynamic therapy on the expression of Enterococcal surface protein (esp) encoding gene in Enterococcus faecalis: Quantitative real-time PCR assessment.

BACKGROUND: During antimicrobial photodynamic therapy (aPDT) in the treatment of endodontic intracanal infection, it is extremely likely that microorganisms would be exposed to sub-lethal doses of PDT (sPDT). Although sPDT would not result in microorganism death, it can considerably influence microbial virulence. This study evaluated the effect of sPDT on gene expression of Enterococci surface protein (esp) as a major virulence factor for biofilm formation in Enterococcus faecalis. MATERIALS AND METHODS: The lethal and sub-lethal potential of aPDT using indocyanine green (ICG), toluidine blue O (TBO), and methylene blue (MB), as the photosensitizers (PSs) and 660, 635, and 810 nm diode laser against E. faecalis was analyzed using colony-forming unit assays. Considering sub-lethal doses of PSs and photo-irradiation time of the diode laser, the expression of esp was evaluated through quantitative Real-time PCR (qRT-PCR). RESULTS: ICG at a concentration of 31.2-1000 µg/mL and both TBO and MB at 6.2-100 µg/mL significantly reducedE. faecalis growth. 660, 635, and 810 nm diode laser with energy density of 93.75-140.62, 137.5-206.25, and 31.25-62.5 J/cm2, reduced the bacterial count. ICG with a concentration of 15.6 µg/mL and irradiation time of 0.5 min, TBO with a concentration of 3.1 µg/mL and irradiation time of 3 min, and MB with a concentration of 3.1 µg/mL and irradiation time of 3 min were found as a sPDT dose against E. faecalis. The esp expression was significantly reduced at sub-lethal doses of ICG compared to TBO (2 fold) and MB (2.4 fold). CONCLUSION: Although all tested PSs showed bacterial reduction, ICG may be considered as the best PS in treating endodontic infection due to its higher efficacy in reduction of esp expression which has a main role in biofilm formation of E. faecalis.

Relationship between Er,Cr:YSGG laser power and surface roughness of lased radicular dentin.

Background: This study sought to assess the effect of Er,Cr:YSGG laser power on the surface roughness of lased radicular dentin using atomic force microscopy (AFM). Methods: Fifteen human radicular dentin samples were randomly divided into five groups: one control (G1, intact) and four experimental groups treated with 0.25W (G2), 0.5W (G3), 0.75W (G4) and 1W (G5) powers of Er,Cr:YSGG laser (2.78µm) at a repetition rate of 20 Hz, with a 600-µm-diameter sapphire tip. After irradiation, surface topography was analyzed by AFM using a Si probe in tapping mode. Quantitative information concerning the arithmetic average roughness (Ra) and quadratic mean roughness (Rq) was obtained from three 5×5µm areas of each sample. The data were analyzed using one-way ANOVA (P<0.05). Results: The Ra and Rq values increased in G2 and G5 and decreased in G3 and G4 groups compared to the control group. The maximum Ra and Rq values were noted in G5, which were significantly higher than the corresponding values in G3 (P<0.05). Conclusion: No direct correlation was found between Er,Cr:YSGG laser power and surface roughness of lased radicular dentin. Laser therapy with a mean power of 0.5W and 1W caused the lowest and highest surface roughness, respectively.

Inhibitory Effects of Antimicrobial Photodynamic Therapy with Curcumin on Biofilm-Associated Gene Expression Profile of Aggregatibacter actinomycetemcomitans.

OBJECTIVES: Periodontitis is an inflammation of periodontal tissues that is caused by the biofilm of periodontal pathogens. Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) is an opportunistic periodontopathogen that can be the cause of periodontal diseases via fimbriae as a virulence factor. In this study, we aimed to determine the expression level of A. actinomycetemcomitans rcpA gene as a virulence factor associated with biofilm formation after antimicrobial photodynamic therapy (aPDT) as a relatively new therapeutic modality. MATERIALS AND METHODS: To determine sub-lethal doses of aPDT against A. actinomycetemcomitans ATCC 33384 strain, we used curcumin (CUR) as a photosensitizer at a final concentration of 40 µmol/ml, which was excited with a light-emitting diode (LED) at the wavelength of 450 nm. Quantitative real-time polymerase chain reaction (qRT-PCR) was then applied to monitor rcpA gene expression in A. actinomycetemcomitans. RESULTS: 10-40 µmol/ml of CUR caused a significant reduction in the growth of A. actinomycetemcomitans compared to control group (P<0.05). Also, the cell viability of A. actinomycetemcomitans was significantly decreased after more than four minutes of LED irradiation. Therefore, the sub-lethal dose of aPDT against A. actinomycetemcomitans was 5 µmol/ml of CUR with three minutes of LED irradiation at a fluency of 180-240 J/cm2, which reduced the expression of the rcpA gene by approximately 8.5-fold. CONCLUSIONS: aPDT with CUR leads to decreased cell survival and virulence of A. actinomycetemcomitans. Thus, CUR-aPDT can be used as an alternative approach for the successful treatment of periodontitis in vivo.

Effect of Various Laser Wavelengths on Temperature Changes During Periimplantitis Treatment: An in vitro Study.

PURPOSE: This study aimed to investigate and compare temperature change during implant decontamination with different laser types (carbon dioxide [Co2]/diode/neodymium-doped yttrium aluminum garnet [Nd:YAG]/erbium-doped yttrium aluminum garnet [Er:YAG]/antimicrobial photodynamic therapy [aPDT]). MATERIAL AND METHODS: Sixty implants were inserted into a bone block cut from a sheep's mandible. A 3 × 8 mm vertical lesion was made at the buccal of each implant. The bone block was placed into a 37°C water bath to simulate the in vivo oral condition. A K-type thermocouple was placed in contact with the implant to register temperature changes at 3 points (apical/middle/coronal). RESULTS: In the entire laser irradiations, the mean of temperature changes remains below 10°C. The apical temperature rise was higher than the coronal and middle regions (P < 0.05), and the apical temperature took longer time to reach the initial temperature (37°C) (P < 0.001). Temperature changes over 10°C occurred at the apical point of the implants with the Co2, Nd:YAG, and diode laser irradiations; however, only the Co2 laser reached the statistical significance in this regard (P < 0.05). CONCLUSION: Our findings indicate the promising results of Er:YAG laser and aPDT in implant decontamination. Precaution should be taken in the application of Nd:YAG, diode, and especially Co2 lasers.