Novel 3-chloro-6-nitro-1H-indazole derivatives as promising antileishmanial candidates: synthesis, biological activity, and molecular modelling studies.

An efficient pathway was disclosed for the synthesis of 3-chloro-6-nitro-1H-indazole derivatives by 1,3-dipolar cycloaddition on dipolarophile compounds 2 and 3. Faced the problem of separation of two regioisomers, a click chemistry method has allowed us to obtain regioisomers of triazole-1,4 with good yields from 82 to 90% were employed. Also, the antileishmanial biological potency of the compounds was achieved using an MTT assay that reported compound 13 as a promising growth inhibitor of Leishmania major. Molecular docking demonstrated highly stable binding with the Leishmania trypanothione reductase enzyme and produced a network of hydrophobic and hydrophilic interactions. Molecular dynamics simulations were performed for TryR-13 complex to understand its structural and intermolecular affinity stability in a biological environment. The studied complex remained in good equilibrium with a structure deviation of ∼1-3 Å. MM/GBSA binding free energies illustrated the high stability of TryR-13 complex. The studied compounds are promising leads for structural optimisation to enhance the antileishmanial activity.

Is computer-guided implant placement with a flapless approach more accurate than with a flapped surgical approach?

Study design Retrospective cohort study.Cohort selection and data analysis In total, 89 implants were placed in 34 patients (19 men and 15 women; average 62.1 years of age) using computer-guided implant surgery with cone beam computed tomography (CBCT). All patients included in this study were adults and the computed-guided implant surgery was planned according to a digital guide protocol based on CBCT. Group 1 patients received the implants with the guide and flapped surgical approach, Group 2 with the guide and flapless approach. Group 3 was the drop-out group which included other patients in who the implant could not be placed according to the guide. CBCT data from before and after the surgeries were superimposed to evaluate the accuracy of implant positioning among all the groups. The differences in distance of the entry point (deviation distance) and in the degree of the insertion angle (deviation angle) were measured on the superimposed CBCT. Statistical analysis was performed with SPSS software and an independent sample t-test was done to analyse the difference of measurements among the groups.Results The authors observed greater accuracy in Group 2 in terms of deviation distance and angulation when compared to Group 1. The deviated position of the implant fixtures was greater in the drop-out group when compared to the guided groups in terms of the displacement of entrance point and the degree of insertion.Conclusions The authors concluded that flapless guided implant surgery is more accurate than flap guided implant surgery. The results of this study can be useful to clinicians in making decisions between flapless surgical approach and flapped approach when using a guide for implant placement.

Does pre-operative clindamycin administration during dental implant surgery reduce implant failure or post-surgical complications?

Study design Prospective randomised placebo-controlled clinical trial.Cohort selection and data analysis Sixty-two healthy adults who underwent single dental implant placement without previous infection of the surgical bed or the need for bone grafting were included in this clinical trial. They were randomly divided into two groups (test and control). The test group was given a single dose of oral clindamycin (600 mg) one hour before surgery and the control group with a placebo. The surgical procedures were carried out by one oral surgeon and all the patients were observed post-operatively on days 1, 7, 14, 28, and 56 by a single observer for clinical, radiological, surgical variables, adverse events, and complications. Statistical analysis was performed with STATA 15 software and the number required to treat or harm (NNT/NNH) was also evaluated.Results In the test group, the authors observed two implant failures and one patient experienced gastrointestinal disturbances and diarrhoea. They also observed post-operative infections in three patients (two in the control group and one in the test group which eventually failed).Conclusions The authors concluded that pre-operative clindamycin administration during dental implant surgery in healthy adults may not reduce implant failure or post-surgical complications.

Are ceramic implant-supported single crowns clinically better than metal-ceramic implant-supported single crowns?

Data sources Data was collected from six databases (Medline, Embase, Web of Science, The Cochrane Central Register of Controlled Trials [CENTRAL], China National Knowledge Infrastructure [CNKI] and Chinese Biomedical Literature Database). Studies published in English and Chinese languages comparing ceramic and metal-ceramic implant-supported fixed dental prostheses (FDPs) were searched. The literature search was performed on studies published until 2018. Manual search of the reference lists of the identified articles was also performed to find related review articles and studies.Study selection Randomised controlled trials (RCTs), prospective and retrospective cohort studies involving the comparison of ceramic and metal-ceramic implant-supported FDPs were selected using the PICOS model for the meta-analysis. For ceramic and metal-ceramic single crowns, the survival rate, marginal adaptation, marginal bone loss, pocket probing depth, crown colour match and mucosal discolouration were assessed. The authors also included studies on survival rate of implant-supported fixed partial dental prostheses (FPDPs) in this meta-analysis.Data extraction and synthesis Two investigators independently screened the articles from the literature search and extracted and analysed data from the included studies. The quality of the included RCTs were assessed using the Cochrane collaboration tool for assessment of risk of bias. For the selected non-randomised studies, the quality and risk of bias were assessed using the Newcastle-Ottawa scale. Twenty studies were included in data synthesis.Results Of the selected 20 studies, ten were RCTs and ten were prospective or retrospective cohort studies.Conclusions The results of this study can be useful to clinicians in making decisions between ceramic and metal-ceramic implant-supported single crowns. This study concluded that the ceramic implant-supported single crown has better crown colour match over a metal-ceramic single crown, but poorer marginal adaptation, and there was no difference observed in other parameters studied (survival rate, marginal bone loss, pocket probing depth and mucosal discolouration). The conclusions on survival rate of implant-supported FPDPs needs to be further evaluated with RCTs with larger samples.

Reductive domino reaction to access chromeno[2,3-c]isoquinoline-5-amines with antiproliferative activities against human tumor cells.

An interaction of homophthalonitrile with salicylaldehydes proceeds as a novel domino reaction and results in the formation of nineteen 12H-chromeno[2,3-c]isoquinoline-5-amine derivatives. Four new bonds and two cycles are forged in a single synthetic operation, employing cheap and eco-friendly ammonium formate, acting both as a catalyst and a reducing agent. The in vitro cytotoxicity tests revealed antiproliferative activities against five human tumor cell lines, including the cisplatin-resistant ovarian carcinoma one (A2780cp8), with inhibitory potency data (IC50) in the low micromolar range in most cases. Molecular docking calculations and fluorescence quenching studies revealed possible binding properties with DNA of the active compounds.

Microwave-Assisted Synthesis of Fluorescent Pyrido[2,3-b]indolizines from Alkylpyridinium Salts and Enaminones.

Pyridinium ylides are well recognized as dipoles for cycloaddition reactions. In its turn, the microwave-assisted interaction of N-(cyanomethyl)-2-alkylpyridinium salts with enaminones unexpectedly proceeds as a domino sequence of cycloisomerization and cyclocondensation reactions, instead of a 1,3-dipolar cycloaddition. The reaction takes place in the presence of sodium acetate as base and employs benign solvents. The optical properties of the resulting pyrido[2,3-b]indolizines were studied, showing green light emission with high fluorescence quantum yields.

Synthesis, Crystal Structure, Hirshfeld Surface Analysis, and Computational Approach of a New Pyrazolo[3,4-g]isoquinoline Derivative as Potent against Leucine-Rich Repeat Kinase 2 (LRRK2).

Ethyl-2-((8-cyano-3,5,9a-trimethyl-1-(4-oxo-4,5-dihydrothiazol-2-yl)-4-phenyl-3a,4,9,9a-tetrahydro-1H-pyrazolo[3,4-g]isoquinolin-7-yl)thio)acetate (5) was synthesized, and its structure was characterized by IR, MS, and NMR (1H and 13C) and verified by a single-crystal X-ray structure determination. Compound 5 adopts a "pincer" conformation. In the crystal, the hydrogen bonds of -H···O, C-H···O, and O-H···S form thick layers of molecules that are parallel to (101). The layers are linked by C-H···π(ring) interactions. The Hirshfeld surface analysis shows that intermolecular hydrogen bonding plays a more important role than both intramolecular hydrogen bonding and π···π stacking in the crystal. The intramolecular noncovalent interactions in 5 were studied by QTAIM, NCI, and DFT-NBO calculations. Based on structural activity relationship studies, leucine-rich repeat kinase 2 (LRRK2) was found to bind 5 and was further subjected to molecular docking studies, molecular dynamics, and ADMET analysis to probe potential drug candidacy.

Multiple lingual cusps trait on mandibular premolars and hypoconulid reduction trait on mandibular first molar in living Jordanian population. Intra- and inter-trait interactions.

The objective was to determine the expression and fluctuating asymmetry of two dental morphological traits in the living Jordanians: The lingual cusp number on the lower premolars (LP1 and LP2) and the hypoconulid (distal cusp) reduction on the lower first molar (LM1). In addition, both intra- trait and inter- trait interactions were analyzed. Three hundred school children (15.5 +/- 0.4 years) were involved. Impressions for the mandibular dental arches were taken, and dental casts were reproduced. The above-mentioned traits were observed. Paired sample t test and nonparametric correlation analysis were used for data analysis. Three-cusped LP1 was found in 11.40 % of the examined students, while the two-cusped LP1 was found in 88.60%. In comparison, the Three-cusped LP2 was found in 61.40% while the two-cusped LP2 was found in 38.60% of the observed subjects. The frequencies of the 4-cusped and 5-cusped LM1 were found to be 8.65% and 91.35%, respectively. Nonparametric correlation analysis revealed positive and statistically significant association between the expression of two lingual cusps on LP1 and on LP2 in both genders (p < 0.01), while there was no significant correlation between expression of two lingual cusps on either LP1 or LP2 and the hypoconulid loss on LM1 in both genders (p > 0.05). Bilateralism was highly significant in the tested traits in both genders (p < 0.001). This finding might be a sign of relatively low environmental stresses experienced by the living Jordanians and/or great ability of its individuals to buffer the adverse effects of such stresses on dental development. This study is a useful addition to the existing literature in that it examines a previously poorly characterized population and assists in placing the contemporary Jordanian population within the current framework of human population groups globally.

Enamel remineralization potential of bioactive glass air abrasion studied via elemental and surface morphology analysis.

Background: This study evaluates the remineralization potential of enamel after bioactive glass (BAG) air abrasion, using Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy Analysis (SEM-EDS), Electron Probe Microanalysis (EPMA), and Atomic Force Microscopy (AFM). Material and Methods: Forty extracted human third molars were divided into four groups with ten samples each. Three groups were subjected to a demineralizing solution of 2.2 mM calcium chloride, 2.2 mM monopotassium phosphate, and 0.05 mM acetic acid, adjusted to a pH of 4.4 using 1 M potassium hydroxide at an intraoral temperature of 37°C for 96 hours. Of the three groups, two were subjected to air abrasion with BAG. One of the air abrasion groups was then further remineralized in 1.5 mM calcium chloride, 0.9 mM sodium phosphate, and 0.15 M potassium chloride, adjusted to a pH of 7.0 at 37°C. The teeth were then evaluated via SEM-EDS and EPMA to measure the calcium-to-phosphorous (Ca:P) ratios, and the surface morphology was investigated using AFM. Results: A measurable decrease in the Ca:P ratio was found after demineralization, which subsequently increased after remineralization. A thin layer of demineralized enamel was removed by the BAG air abrasion. AFM image analysis showed the presence of pits on the surface, which decreased in depth after demineralization, and further after BAG abrasion. Remineralized samples, in contrast, showed a slight increase in pit depth. While the observation of remineralization was statistically significant throughout our study, we could not find any evidence for BAG retention on the surface of the enamel. Conclusions: It is demonstrated that BAG, when delivered via air abrasion, indeed contributes to remineralization of the enamel; however, it does not seem to be a direct result of the presence of retained glass beads on the enamel surface. Given the increase of the Ca:P ratio after remineralization, a possible therapeutic benefit was observed, potentially reducing the probability of fractures in weakened enamel. Key words:Enamel, Demineralization, Remineralization, White Spot Lesions, Bioactive Glass, Air Abrasion, Energy Dispersive X-ray Spectroscopy, Electron Probe Microanalysis, Atomic Force Microscopy, Ca:P ratio, surface morphology.

An overview of orthodontic malpractice liability based on a survey and case assessment review.

Background: The purpose of this survey study and case review was to identify 1) the common causes related to filing a malpractice claim against an orthodontist and, 2) the factors mitigating against a potential malpractice claim in the United States (U.S). The objectives of the case review were to examine the current state of orthodontic malpractice litigation from a cause and mitigating point of view. Material and Methods: Data for this research was collected and reviewed using the following two methods: 1) A survey questionnaire on aspects of malpractice liability was electronically distributed to 2,241 active U.S. members of the American Association of Orthodontists (AAO). 2) Legal cases were reviewed on the online legal research database Lexis Advance Research, and 35 cases were analyzed. Results: Survey questionnaire results and legal case review results are as follows: 1) 77 orthodontists completed the survey. 9.1% of the respondents reported a malpractice claim having been filed against them with periodontal issues accounting for most of the claims. Survey participants reported good doctor-patient communication as being the most relevant contributory factor and most relevant mitigating factor in malpractice claims. 2) Negligence is the main reason patients sue a doctor for clinically related litigation, and failure to obtain a proper informed consent from the patient is the main cause of action for non-clinically related litigation. Conclusions: Most respondents reported doctor-patient communication, periodontal issues, and a lack of informed consent as the main triggering elements of a lawsuit, which is similar to other studies and case review analysis. Good doctor-patient rapport was ranked as being most helpful in mitigating a potential claim, which is also similar to other studies. Another aspect of the survey questionnaire that was evaluated was whether a non-orthodontist can provide expert testimony against an orthodontist, with most respondents reporting that this is not possible. It has been ruled, though, that a general dentist can be an expert witness and provide expert testimony against an orthodontist in a lawsuit depending on the circumstances. Negligence was the most common cause of clinically related orthodontic litigation, and a failure of the practitioner to obtain a proper informed consent from the patient was the most common cause of non-clinically related orthodontic litigation. Key words:Orthodontist, malpractice, legal, lawsuit, liability, medicolegal.

Screening for obstructive sleep apnea by orthodontists in the United States - A survey study.

Background: Obstructive Sleep Apnea (OSA), a sleep-related breathing disorder that can affect both children and adults with systemic co-morbidities beyond disrupted sleep yet remains underdiagnosed in a substantial portion of the pediatric and adult orthodontic patient populations. The objective of this study was to assess the prevalance of orthodontists screening patients for OSA, their confidence level in screening, and to identify the various screening methods most commonly used in practice. Material and Methods: A survey on screening for OSA was emailed to 6,675 members of the American Association of Orthodontists (AAO) in the United States. Frequency distribution of different responses and their association with various demographic factors was assessed. Results: Out of 234 orthodontists completing the survey, 62% reported screening all of their patients for OSA, while 38% reported doing no OSA screening at all. More hours of continuing education (CE) and younger ages were observed to be statistically significantly associated with practice of screening for OSA (p<0.001 and 0.034, respectively, on regression analysis). Role of longer practice duration observed to be significant on univariate analysis, lost its statistical significance on regression analysis. Conclusions: CE hours on OSA seemed to be the most important factor that motivated the orthodontist to screen for OSA. A majority of orthodontists in the 35-54 year old age-group were screening their patients for OSA. Key words:Orthodontics, obstructive sleep apnea, screening, survey study.

Public Perceptions and Understanding of Risks Associated with Do-It-Yourself Orthodontics: A Survey Study.

Background: The purpose of this study was to evaluate general public's perception, knowledge and preferences on orthodontic treatment rendered by an orthodontist versus the "Do-It-Yourself" orthodontics (DIYO) concept without professional supervision. The secondary objective was to assess laypeople's awareness on the risks and limitations of DIYO. Material and Methods: A 24-question online survey questionnaire was administered to 526 laypeople who had no professional experience or background in dentistry and orthodontics. All data was collected over 3 days (July 20-23, 2020) by Qualtrics server and forwarded to the principal investigator. Statistical analysis was done with statistical software SPSS® version 26. Results: The most important reason for laypeople to opt for DIYO is financial reason. People who have undergone orthodontic treatment know the difference between a general dentist and an orthodontist, whereas people who have not had orthodontic treatment are less likely to know the difference. Of the 285 people who did not receive orthodontic treatment before by a dental professional, 43 have considered DIYO. 122 of the 526 people considered DIYO, and 79 of the 122 had orthodontic treatment before. 26 of the 122 did not consider the clinical exam and diagnostic records important and would be comfortable without in-person supervision. 83 of the 122 would be comfortable not having in-person supervision, and still considered this treatment modality "Doctor-Directed". Conclusions: The main reason laypeople utilize DIYO is the low cost. Some DIYO users do not consider risks involved and a small percentage consider their own dentist to be responsible if any issues arise with DIYO. One third of survey respondents will consider DIYO in the future. Key words:Do-It-Yourself (DIY), Direct-To-Consumer (DTC), Adult, Orthodontics, Dentistry, Surveys and Questionnaires.

Guided bone regeneration with a synthetic biodegradable membrane: a comparative study in dogs.

OBJECTIVES: The aim of the present study was to compare a newly developed biodegradable polylactide/polyglycolide/N-methyl-2-pyrrolidone (PLGA/NMP) membrane with a standard resorbable collagen membrane (RCM) in combination with and without the use of a bone substitute material (deproteinized bovine bone mineral [DBBM]) looking at the proposed tenting effect and bone regeneration. MATERIALS AND METHODS: In five adult German sheepdogs, the mandibular premolars P2, P3, P4, and the molar M1 were bilaterally extracted creating two bony defects on each site. A total of 20 dental implants were inserted and allocated to four different treatment modalities within each dog: PLGA/NMP membrane only (Test 1), PLGA/NMP membrane with DBBM (Test 2), RCM only (negative control), and RCM with DBBM (positive control). A histomorphometric analysis was performed 12 weeks after implantation. For statistical analysis, a Friedman test and subsequently a Wilcoxon signed ranks test were applied. RESULTS: In four out of five PLGA/NMP membrane-treated defects, the membranes had broken into pieces without the support of DBBM. This led to a worse outcome than in the RCM group. In combination with DBBM, both membranes revealed similar amounts of area of bone regeneration and bone-to-implant contact without significant differences. On the level of the third implant thread, the PLGA/NMP membrane induced more horizontal bone formation beyond the graft than the RCM. CONCLUSION: The newly developed PLGA/NMP membrane performs equally well as the RCM when applied in combination with DBBM. Without bone substitute material, the PLGA/NMP membrane performed worse than the RCM in challenging defects, and therefore, a combination with a bone substitute material is recommended.

Hypocone reduction and Carabelli's traits in contemporary Jordanians and the association between Carabelli's trait and the dimensions of the maxillary first permanent molar.

The objective of this study is to determine the prevalence of expression and bilateralism of two dental morphological traits in contemporary Jordanians: The hypocone reduction trait on the maxillary second permanent molar and Carabelli's trait on maxillary permanent first and second molars. Furthermore, inter-trait correlation and the relationship of Carabelli's traits with upper first molar dimensions were investigated. Three hundred subjects of school children at their 10th grade and of an average age of 15.5 +/- 0.4 years were involved. Alginate impressions for the maxillary arch were taken, dental casts were reproduced. The selected accurate casts were of 132 male- and 155 female-students. The frequencies of hypocone reduction trait on the maxillary second molar and Carabelli's trait on the maxillary molars were examined. Buccolingual and mesiodistal diameters of the maxillary first molar were measured and recorded. Paired Sample t test and Nonparametric Correlation analysis were used for data analysis. Hypocone reduction trait on the maxillary second molar was found in 29.8% of the examined students. Positive forms of Carabelli's trait on first and second molars were observed in 65.0% and 3.8%, respectively. Nonparametric correlation analysis revealed positive association between Carabelli's trait on first molar and hypocone reduction trait on the maxillary second molar. The presence of Carabelli's trait on first molar was strongly associated with the increase of buccolingual, but not the mesiodistal, diameter. Bilateralism was found highly significant in the tested traits and both genders (p < 0.001). This finding might be a sign of relatively low environmental stresses in the living Jordanian population and/or great ability of its individuals to buffer the adverse effects of such stresses.

Practice of lingual orthodontics and practitioners' opinion and experience with lingual braces in the United States.

BACKGROUND: A survey was done on practicing Orthodontists in the United States on their experience with lingual orthodontics. The objectives of this survey study were to assess 1) the satisfaction level with cases treated with lingual orthodontics, 2) factors that influence clinicians' decision to utilize or not utilize lingual braces in their current practices, and 3) intention of using lingual braces in their future practices, if not used currently, in the U.S. MATERIAL AND METHODS: A survey questionnaire was electronically distributed to 2,200 active U.S. members of the American Association of Orthodontists (AAO). RESULTS: 85 orthodontists completed the survey. About 25% of respondents practiced lingual orthodontics. Direct mentorship was the most common approach used by orthodontists to learn lingual technique. The most used lingual system among the clinicians that use lingual braces was INBRACE® (34.6%). All respondents were either satisfied or very satisfied with their treatment outcome of cases treated with lingual braces. Improved esthetics and practice differentiation were perceived to be the biggest advantages of practicing lingual orthodontics. Biggest challenges with lingual orthodontics were found to be patient discomfort, cost, longer chair time and technical difficulties. Most common reason for not using lingual braces was technical difficulty, followed by availability of alternative appliances, lack of demand and patient discomfort. Approximately, 70% of those that did not use lingual orthodontics in their current practices responded that they were very likely to incorporate lingual orthodontics in their future practices. CONCLUSIONS: Overall outcome satisfaction level with cases treated with lingual braces was high among the orthodontists that practiced lingual orthodontics. There seemed to be a strong interest in incorporating lingual orthodontics in future practices by clinicians that did not use lingual braces in their current practices. Some of the factors that influenced clinicians' decision to practice lingual orthodontics were improved esthetics, practice differentiation and increased case acceptance. Technical difficulties, availability of alternative appliances, lack of demand and patient discomfort were some of the factors that were identified to have influenced practitioners' decision to not offer lingual orthodontics in their current practices. Key words:Orthodontic brackets, Lingual braces, Lingual orthodontics.

Orthodontists' preference on type of rigid fixed functional appliance for skeletal Class II correction: A survey study.

BACKGROUND: Rigid fixed functional appliances are most commonly used to correct skeletal Class II malocclusions. The objective of this study was to assess orthodontists' preference of different rigid fixed functional appliances used in the U.S.A for correction of skeletal Class II malocclusions. MATERIAL AND METHODS: A survey on use and preference of rigid fixed functional appliances for skeletal Class II correction was emailed to 2,227 members of the American Association of Orthodontists (AAO) in the U.S.A. Frequency distribution of different responses and their association with demographic factors was assessed. RESULTS: Out of 140 orthodontists completing the survey, 110 responded as using rigid fixed functional appliances. Eight incomplete responses were eliminated from data analysis. 51.5% (68/132) orthodontists used rigid fixed functional appliances. The most preferred rigid fixed functional appliance was the Herbst appliance with 72% response followed by Mandibular Anterior Repositioning Appliance (24%) and AdvanSync (4%). There was no statistically significant difference in use of rigid fixed functional appliances between different age groups (p=0.284). However, the 40-54 age group used the most rigid fixed functional appliances in practice, followed by the 25-39 year age group and the 55-69 age group using these appliances the least. There was statistical significance between the type of practice setting one works in and the use of rigid fixed functional appliances in practice (p=0.022). CONCLUSIONS: About 52% of orthodontists use rigid fixed functional appliances to correct skeletal Class II malocclusions. The Herbst appliance is the most commonly used and most preferred amongst all rigid fixed functional appliances with a 72% preferred rate. Key words:Orthodontic, Rigid fixed functional appliance, Skeletal Class II, Class II Malocclusion, Mandibular retrognathism, Herbst, Mandibular Anterior Repositioning Appliance (MARA), AdvanSync, Molar to molar, M2M.

Enhanced Emission of Zinc Nitride Colloidal Nanoparticles with Organic Dyes for Optical Sensors and Imaging Application.

Herein, we have reported on the efficiency of inorganic Zn3N2 nanoparticles for labeling plant cells and animal cells toward imaging applications with negligible toxicity. We have synthesized zinc nitride (Zn3N2) colloidal nanoparticles with an average size of 25 nm at room temperature. The optical band gap of the prepared Zn3N2 nanoparticles is 2.8 eV and gives a visible range emission at 415 nm. With the addition of Zn3N2 colloids to organic dyes such as protoporphyrin, flavin adenine dinucleotide, fluorescein, and neutral red, the emission intensity of the organic dyes enhanced from 3 to 20 times. The molecular simulation and lifetime studies evidence the possibility of energy transfer from zinc nitride to organic dyes. The enhancement of dye intensity in the presence of Zn3N2 enhanced the vicinity of the cellular environment during confocal imaging of plant cells and animal cells. The detailed results suggested Zn3N2 for bioimaging and biosensor applications.

Survey on awareness and preference of ceramic bracket debonding techniques among orthodontists.

BACKGROUND: The objectives of this study was to evaluate the awareness of different ceramic bracket debonding techniques among orthodontists in the USA and the most commonly used debonding technique for ceramic bracket removal. MATERIAL AND METHODS: A survey on preference for debonding and awareness of debonding techniques was emailed to 2,227 members of the American Association of Orthodontists (AAO). RESULTS: 119 orthodontists completed the survey. 111 responses were included in the study analysis of ceramic bracket users. The most common technique used was mechanical debonding. 86.5% used a specially designed bracket removing plier from the manufacturer. Overall, there were 59.5% of surveyed orthodontists who were aware of electrothermal debonding, 73% were unaware of ultrasonic debonding and 83.8% were unaware of laser debonding. There were more orthodontists with an affiliation with an academic institution aware of electrothermal debonding (p=0.002). There also was a trend of orthodontists having no affiliation with an institution who were unaware of laser debonding (p=0.015). CONCLUSIONS: This survey showed that the majority of orthodontists who responded to the questionnaire were unaware of alternative debonding techniques of ceramic brackets. All orthodontists who use ceramic brackets utilized mechanical debonding technique. Key words:Orthodontic ceramic brackets, mechanical, electrothermal, ultrasonic, laser debonding.

Aza-Henry and aza-Knoevenagel reactions of nitriles for the synthesis of pyrido[1,2-a]indoles.

N-(Propargyl)indole-2-carbonitriles undergo DBU-catalyzed addition of CH-acids to nitriles, followed by cyclization to give 9-aminopyrido[1,2-a]indoles. The reaction proceeds through the initial formation of a push-pull enamine, alkyne-allene rearrangement and intramolecular nucleophilic cyclization. Nitromethane and malonate esters can be employed as the CH-acids. The resulting compounds were found to exhibit fluorescence properties.

Biofilm on dental implants: a review of the literature.

PURPOSE: The aim of this article was to review the current literature with regard to biofilm formation on dental implants and the influence of surface characteristics (chemistry, surface free energy, and roughness) of dental implant and abutment materials and their design features on biofilm formation and its sequelae. MATERIALS AND METHODS: An electronic MEDLINE literature search was conducted of studies published between 1966 and June 2007. The following search terms were used: biofilm and dental implants, biofilm formation/plaque bacterial adhesion and implants, plaque/biofilm and surface characteristics/roughness/surface free energy of titanium dental implants, implant-abutment interface and plaque/biofilm, biofilm and supragingival/subgingival plaque microbiology, biofilm/plaque and implant infection, antibacterial/bacteriostatic titanium, titanium nanocoating/nanopatterning, antimicrobial drug/titanium implant. Both in vitro and in vivo studies were included in this review. RESULTS: Fifty-three articles were identified in this review process. The articles were categorized with respect to their context on biofilm formation on teeth and dental implant surfaces and with regard to the influence of surface characteristics of implant biomaterials (especially titanium) and design features of implant and abutment components on biofilm formation. The current state of literature is more descriptive, rather than providing strong data that could be analyzed through meta-analysis. Basic research articles on surface modification of titanium were also included in the review to analyze the applications of such studies on the fabrication of implant surfaces that could possibly decrease early bacterial colonization and biofilm formation. CONCLUSIONS: Increase in surface roughness and surface free energy facilitates biofilm formation on dental implant and abutment surfaces, although this conclusion is derived from largely descriptive literature. Surface chemistry and the design features of the implant-abutment configuration also play a significant role in biofilm formation.