Distinctive Nucleic Acid Recognition by Lysine-Embedded Phenanthridine Peptides.

Three new phenanthridine peptide derivatives (19, 22, and 23) were synthesized to explore their potential as spectrophotometric probes for DNA and RNA. UV/Vis and circular dichroism (CD) spectra, mass spectroscopy, and computational analysis confirmed the presence of intramolecular interactions in all three compounds. Computational analysis revealed that compounds alternate between bent and open conformations, highlighting the latter's crucial influence on successful polynucleotide recognition. Substituting one glycine with lysine in two regioisomers (22, 23) resulted in stronger binding interactions with DNA and RNA than for a compound containing two glycines (19), thus emphasizing the importance of lysine. The regioisomer with lysine closer to the phenanthridine ring (23) exhibited a dual and selective fluorimetric response with non-alternating AT and ATT polynucleotides and induction of triplex formation from the AT duplex. The best binding constant (K) with a value of 2.5 × 107 M-1 was obtained for the interaction with AT and ATT polynucleotides. Furthermore, apart from distinguishing between different types of ds-DNA and ds-RNA, the same compound could recognize GC-rich DNA through distinct induced CD signals.

Undergraduate Students' Knowledge on Temporomandibular Disorders in Croatia.

The aim of this study was to evaluate Croatian undergraduate students' knowledge based on what they learned in the recent course, as well as the students' own judgment and opinions about geriatric dentistry education concerning temporomandibular disorders (TMDs) of the elderly. The study was carried out by means of a questionnaire administered in the last study year to students of the School of Dental Medicine, University of Zagreb and students of the Department of Dental Medicine at the School of Medicine, University of Rijeka. Th e questionnaire included questions about relevant specific knowledge on TMD, and statements related to their own opinion about geriatric dentistry education received during the study. Regarding students' knowledge related to TMDs, students from Rijeka gave more positive answers (p=0.012). Students from Rijeka gave more positive answers regarding physical therapy for treatment of TMD (p=0.004) and disc displacement and osteoarthritis as the most common disorders of the temporomandibular joint (p=0.031). Students from Zagreb were more unsatisfi ed with the skills in the field of geriatric dentistry (disagreed 57.45%) than students from Rijeka (45.83% had neutral standpoint and 37.50% agreed) (p=0.005). The level of the participants' knowledge pointed to the need of improving undergraduate dental teaching about the specific geriatric education, including knowledge about TMD.

Evaluation of Bone Healing After Osteotomies Prepared With Er:YAG Laser in Contact and Noncontact Modes and Piezosurgery--An Animal Study.

PURPOSE: To analyze the healing of bone tissue treated with Er:YAG laser contact and noncontact modes of and piezosurgery in a rat model using triangular laser profilometry. MATERIALS AND METHODS: Twenty-four 10-week-old adult male Wistar rats were used in the study. Three osteotomies on the medial part of tibia were performed in each animal, 1 in the right tibia and 2 in the left tibia. The osteotomies were performed with a piezoelectric device set at maximal power and the Er:YAG laser in contact mode (power, 7.5 W; pulse energy, 375 mJ; repetition rate, 20 Hz; MSP mode) and noncontact mode (power, 7.5 W; pulse energy, 750 mJ; repetition rate, 10 Hz; QSP mode) with a novel type of circular, digitally controlled handpiece (x-Runner). After surgery, 6 animals were immediately euthanized (group 1), and the others were euthanized after 1 week (group 2, n = 6), 2 weeks (group 3, n = 6), and 3 weeks (group 4, n = 6). Bone healing after osteotomy was analyzed using a 3-dimensional laser scanning technique (ie, laser triangulation profilometry). RESULTS: The volume reduction rates are similar for all 3 techniques (0.2 to 0.25 mm(3) per week). Greater volume reduction of 0.25 mm3 per week was observed for the Er:YAG laser in noncontact mode (x-Runner). After 3 weeks, almost complete healing of the prepared osteotomy was observed. CONCLUSION: Within the limitations of this study, the osteotomies performed by the Er:YAG laser in digitally controlled noncontact mode healed the fastest.

Antimicrobial efficacy of photodynamic therapy, Nd:YAG laser and QMiX solution against Enterococcus faecalis biofilm.

BACKGROUND: Lasers have been recommended in final root canal disinfection protocol, however, there is no clear evidence about their efficacy against bacteria in biofilms. The aim of the study was to evaluate and compare the disinfection effect of antimicrobial photodynamic therapy (aPDT), Nd:YAG laser and QMiX solution against Enterococcus faecalis biofilm. METHODS: The study sample consisted of 65 dentine slices, which were inoculated with E. faecalis and incubated anaerobically for three weeks. The dentine discs were randomly allocated to one of the following experimental groups: aPDT (100 mW, 10 mg/ml phenothiazinium chloride, 1 min), Nd:YAG laser (2 W, 15 Hz, 4×5 s), QMiX solution (1 min). Positive controls did not receive any treatment and negative controls were treated with 5.25% NaOCl. To harvest surviving adherent cells, each dentine sample was transffered to a test tube containing of TSB, serial ten-fold dilutions were made and aliquot of 1 ml was plated onto blood agar plates and incubated for 48 h. Colony forming units grown were counted and transformed into actual counts based on the dilution factor. The remaining viable cells after each protocol were analysed by FISH. RESULTS: The aPDT and the QMiX solution were equally effective, with the reduction rate of E. faecalis CFUs of 98.8% and 99.3% respectively (p=1.107). The Nd:YAG laser caused 96% reduction of E. faecalis (P<0.001). CONCLUSION: The aPDT and the QMiX solution showed similar antibacterial efficacy against old E. faecalis biofilm, followed by Nd:YAG irradiation.

Implant stability comparison of immediate and delayed maxillary implant placement by use of resonance frequency analysis--a clinical study.

The purpose of this study was to objectively evaluate the stability of dental implants by use of resonance frequency analysis (RFA). In this study, 60 Nobel Replace Tapered Groovy implants were placed in the premolar region of the maxilla in 60 patients. Thirty implants were placed immediately after tooth extraction and 30 implants were placed in healed bone sites. Implant stability quotient (ISQ) was obtained by use of the Osstell Mentor device and was recorded at the time of implant placement (T1) and 20 weeks after placement, at the time of implant loading (T2). All implants were not functionally loaded during the follow up period. Data were analyzed using simple linear regression. No implant failures were reported in the 6-month follow up period. The mean ISQvalue for immediate implant placement was 61.43 at T1 and 66.23 at T2. The implants placed in healed bone showed higher ISQvalues compared to the immediately placed implants (mean ISQvalue was 64.17 at T1 and 68.83 at T2). Differences in the mean ISQ values were statistically significant (p < 0.001). After the completed period of osseointegration, the mean ISQ value was 4.8 for immediately placed implants compared to 4.67 for implants placed in delayed sites.

The antimicrobial effectiveness of photodynamic therapy used as an addition to the conventional endodontic re-treatment: a clinical study.

BACKGROUND: The purpose of the study was to evaluate the efficacy of antimicrobial photodynamic therapy (aPDT) used as an adjunct to the endodontic re-treatment in the eradication of microorganisms from previously filled root canals. METHODS: The study sample consisted of 21 randomly selected patients with root filled and infected root canal system with chronic apical periodontitis on incisors or canines, who have had previously endodontic treatment. Microbiological samples from the root canals were collected after accessing the canal, following the endodontic re-treatment and after the aPDT procedure. During instrumentation, the root canals were irrigated with 2.5% sodium hypochlorite (NaOCl), and the final irrigation protocol included 17% ethylenediaminetetraacetic acid followed by NaOCl. Root canals were filled with a phenothiazinium chloride and irradiated with a diode laser (λ=660 nm, 100 mW) for 1 min. Microbiological samples from the root canals were cultivated on selective plates, and the identification was done by micromorphology, macromorphology and different API strips as well as bacterial counts (colony forming units). RESULTS: Fourteen bacteria species were isolated from the root canals initially, with a mean value of 4.57 species per canal. Although endodontic re-treatment alone produced a significant reduction in the number of bacteria species (p<0.001), the combination of endodontic treatment and aPDT was statistically more effective (p<0.001). No bacteria were cultivated from the main root canals of 11 teeth. CONCLUSION: The results indicated that the aPDT used as an adjunct to the conventional endodontic therapy achieved a significant further reduction of intracanal microbial load.

Antimicrobial efficacy of Er,Cr:YSGG laser-activated irrigation compared with passive ultrasonic irrigation and RinsEndo(®) against intracanal Enterococcus faecalis.

OBJECTIVE: The aim of this study was to evaluate the antibacterial efficacy of active irrigation techniques: Erbium, chromium: yttrium, scandium, gallium, garnet (Er,Cr:YSGG) laser-activated irrigation (LAI), passive ultrasonic irrigation (PUI), RinsEndo(®), and conventional syringe irrigation, against intracanal Enterococcus faecalis. MATERIALS AND METHODS: Root canals of 100 human extracted teeth were instrumented, sterilized in plasma, contaminated with E. faecalis, and incubated for 10 days. The samples were randomly distributed into four experimental groups (n=20 each): I: LAI by Er,Cr:YSGG (1.25 W, 20 Hz) for 4×5 sec; II. PUI for 60 sec; III. RinsEndo(®) system for 60 sec; IV. 30 gauge syringe irrigation for 60 sec; and one positive control group (n=10). In all experimental groups, 2.5% sodium hypochlorite (NaOCl) was used as an irrigant, whereas the positive controls were rinsed with saline. The root canals were sampled by flushing with saline solution before and after the treatments, serially diluted, and cultured. The presence or absence of E. faecalis in the root canals was checked by polymerase chain reaction. RESULTS: There were no differences among the three active irrigation techniques (p>0.05), which were more effective than the conventional syringe irrigation (p<0.001). CONCLUSIONS: LAI, PUI, and RinsEndo were equally effective in the elimination of intracanal 10-day-old E. faecalis. However, LAI generated more negative bacterial samples, which warrants further investigations.

Morphological and ultrastructural comparative analysis of bone tissue after Er:YAG laser and surgical drill osteotomy.

OBJECTIVE: The purpose of this study was to analyze morphological, chemical, and crystallographic changes of bone tissue after osteotomy performed with an erbium:yttrium-aluminium-garnet (Er:YAG) laser and a low speed pilot drill. MATERIALS AND METHODS: Bone blocks were prepared from porcine ribs, and on each block, two tunnel preparations were performed using the Er:YAG laser (pulse energy: 1000 mJ, pulse duration: 300 µs, pulse repetition rate: 20 Hz) or the low-speed surgical pilot drill. The morphological changes of the cortical and the spongious surface of the tunnel preparations were analyzed under the field emission scanning electron microscopy (FE-SEM) at low and high resolution. The distribution and the level of chemical elements in the treated surfaces were evaluated by qualitative and semiquantitative energy dispersive x-ray analysis (SEM-EDX). Diffraction x-ray analysis was used to detect any differences and thermally induced modifications of hydroxyapatite crystals. RESULTS: FE-SEM revealed sharp edges of the Er:YAG preparations, with empty intertrabecular spaces and no signs of carbonization. In the drill group, the surface of the preparations was smooth, completely covered with smear layer and microcracks, and with hairy-like irregularities on the edges. SEM-EDX analysis did not reveal any differences in the number of specific chemical elements between the laser and the drill group. There were no thermally induced modifications of hydroxyapatite crystal structure in the bone tissue in either group. CONCLUSIONS: The Er:YAG laser ablation did not cause any chemical or crystallographic changes of the bone tissue. Compared with the drill, Er:YAG laser created well-defined edges of the preparations, and cortical bone had no smear layer.

The Use of Lasers in Disinfection and Cleanliness of Root Canals: a Review.

The outcome of root canal treatment is based on efficient disinfection of the root canal system and prevention of reinfection. Current chemomechanical cleaning methods do not always achieve these goals, and insufficient root canal disinfection is the main reason for endodontic failure. Due to high energy content and specific characteristics of laser light, laser treatment has been proposed for cleaning and disinfecting the root canal system. This paper reviews the literature covering the effect of Er:YAG, Er,Cr:YSGG, Nd:YAG and diode laser on the root canal wall in the removal of smear layer and against intracanal bacteria. Recently, the use of laser energy to induce cavitation and acoustic streaming of intracanal irrigants has been investigated. Based on recent literature, it can be concluded that lasers have bactericidal effects. However, they still cannot replace sodium hypochlorite and should be considered as an adjunct to the current chemical root canal disinfection protocols. Certain lasers can help in removing the smear layer and debris and can modify the morphology of the root canal wall. Unfortunately, there have not been enough randomized clinical studies evaluating endodontic treatment outcome following the use of laser.

Assessing Health-Related Quality of Life with Antimicrobial Photodynamic Therapy (APDT) and Low Level Laser Therapy (LLLT) after Third Molar Removal.

INTRODUCTION: The purpose of this study was to evaluate the antimicrobial photodynamic therapy (APDT) and low level laser therapy (LLLT) on wound healing, pain intensity, swelling problems, halitosis and the postoperative usage of analgesics after surgical removal of lower third molars. METHODS: One hundred and fifty patients, randomly divided into three groups were selected (50 per each group). The P1 group received the APDT after a third molar surgery, the P2 group received the LLLT and the C group (control group) was without any additional therapy after surgery. A photoactive substance was applied in the APDT study group before suturing. After 60 seconds the photosensitive substance was thoroughly washed with saline water and the laser light was applied in two intervals (30 seconds each). The irradiation power was 50 mW while the wavelength was 660 nm. The laser therapy in P2 group was performed before suturing and the laser light was applied also in two intervals (90 seconds each), the irradiation power was 90 mW while the wavelength was the same as in the first group - 660 nm. Postoperative follow-ups were scheduled on the third and the seventh day in patients who received laser therapy. RESULTS: The results of the postoperative evaluation showed that there was a statistically significant difference in the postoperative wound healing, pain intensity, swelling problems, halitosis and analgesics intake between patients in all three groups (p<0.001). The patients that were subjected to APDT (P1) had the least postoperative problems. After the laser therapy (P1 and P2) wound healing was without any complications, opposite from the patients from the C group (p<0.001). Postoperative application of a laser therapy significantly reduced patient's use of analgesics over the observed period of time (p<0.001). CONCLUSION: Both modalities of laser therapy significantly reduced postoperative problems after surgical removal of third lower molars with the best results in both laser groups.