Quantification of vital adherent Streptococcus sanguinis cells on protein-coated titanium after disinfectant treatment

The quantification of vital adherent bacteria is challenging, especially when efficacy of antimicrobial agents is to be evaluated. In this study three different methods were compared in order to quantify vital adherent Streptococcus sanguinis cells after exposure to disinfectants. An anaerobic flow chamber model accomplished initial adhesion of S. sanguinis on protein-coated titanium. Effects of chlorhexidine, Betadine®, Octenidol®, and ProntOral® were assessed by quantifying vital cells using Live/Dead BacLight™, conventional culturing and isothermal microcalorimetry (IMC). Results were analysed by Kruskal-Wallis one-way analysis of variance. Live/dead staining revealed highest vital cell counts (P0.05), indicating equivalent numbers of bacteria were created and disinfectants delayed growth but did not eliminate it. In conclusion, contrary to culturing, live/dead staining enables detection of cells that may be viable but non-cultivable. Microcalorimetry allows unique evaluation of relative disinfectant effects by quantifying differences in time delay of regrowth of remaining vital cell

Minimum size and positioning of imaging field for CBCT scans of impacted maxillary canines

Objectives: In children and adolescents, cone-beam computed tomography (CBCT) is frequently used for localization of unerupted or impacted teeth in the anterior maxilla. CBCT causes a higher radiation dose than conventional intraoral and panoramic imaging. The objective was to analyze the location of impacted canines in a three-dimensional coordinate and thereby optimize the CBCT field-of-view (FOV), for radiation dose reduction.Materials and methods: Location of 50 impacted maxillary canines of children under 17 years was retrospectively evaluated from CBCT scans. The minimum and maximum distances of any part of the right- and left-side canines to three anatomic reference planes were measured to assess the adequate size and position of a cylindrical image volume.Results: A cylinder sized 39.0 (diameter)×33.2 (height) mm, with its top situated 13.8 mm above the hard palate, its medial edge 8.4 mm across the midline, and anterior edge 2.5 mm in front of the labial surface of maxillary central incisors fitted all the analyzed canines.Conclusions: In this sample, the FOV required for imaging maxillary impacted canines was smaller than the smallest FOV offered by common CBCT devices. We encourage development of indication-specific CBCT imaging programs and aids to facilitate optimum patient positioning.Clinical relevance: An impacted maxillary canine is a common dental problem and a frequent indication for 3D imaging particularly in growing individuals. This article focuses on the optimization of CBCT of impacted canines. Our recommendation of a reduced FOV promotes radiation safety.</p

A pseudo-randomised clinical trial of in situ gels of fluconazole for the treatment of oropharngeal candidiasis

<p>Abstract</p> <p>Background</p> <p>Oropharyngeal candidasis is a common opportunistic infection seen in immunocompromised patients. Fluconazole has a broad spectrum antifungal activity including a wide variety of <it>candida </it>species. Aim of the present investigation was to formulate and find out the relative efficacy of <it>in situ </it>gels of fluconazole.</p> <p>Method</p> <p>The <it>in situ </it>gels were prepared using polymers which exhibited sol-to-gel phase transition due to change in specific physico-chemical parameters, such as ion triggered system using gellan gum (0.5% w/v) along with sodium carboxylmethylcellulose (0.35%w/v). The study design was bicenter, 'pseudo-randomised, single blind trial conducted in Mangalore., India, which includes 15 HIV positive patients, 15 patients with partial or completes dentures, and 15 patients who were treated with (active control) fluconazole tablets 100 mg/day for 14 days. Severity of disease was scored clinically before treatment and at clinical evaluations on day 3, 7, 14, 18, 21, 35, and 42. Semiquantitative microbiological cultures of oral swabs were also obtained on same days.</p> <p>Results</p> <p>All patients had mycological documented oropharyngeal candidiasis and were treated with fluconazole (0.5%w/v) <it>in situ </it>gels for 14 days Severity of disease was scored clinically before treatment and at different predetermined time intervals along with semi quantitative culture of oral swabs. The clinical response rate showed 97% cure after 14 days in the treated with <it>in situ </it>gel. In comparison, the control group treated with fluconazole tablets showed 85% improvement in symptoms of oral candidiasis. The patients suffering from HIV infection showed relapse in oral candidiasis at the end of 21 days. The patients having oral candidiasis due to partial or complete dentures showed complete recovery and were free from signs and symptoms of oral candidiasis.</p> <p>Conclusions</p> <p>The <it>in situ </it>gel formulation of fluconazole was well tolerated with no severe adverse reaction and offers a better alternative to tablet formulation in the treatment of oropharyngeal candidasis.</p> <p>Trial registration</p> <p>Current Controlled Trails <a href="http://www.controlled-trials.com/ISRCTN90634047">ISRCTN90634047</a></p

Human mandibular shape is associated with masticatory muscle force

Understanding how and to what extent forces applied to the mandible by the masticatory muscles influence its form, is of considerable importance from clinical, anthropological and evolutionary perspectives. This study investigates these questions. Head CT scans of 382 adults were utilized to measure masseter and temporalis muscle cross-sectional areas (CSA) as a surrogate for muscle force, and 17 mandibular anthropometric measurements. Sixty-two mandibles of young individuals (20-40 years) whose scans were without artefacts (e.g., due to tooth filling) were segmented and landmarked for geometric morphometric analysis. The association between shape and muscle CSA (controlled for size) was assessed using two-block partial least squares analysis. Correlations were computed between mandibular variables and muscle CSAs (all controlled for size). A significant association was found between mandibular shape and muscle CSAs, i.e. larger CSAs are associated with a wider more trapezoidal ramus, more massive coronoid, more rectangular body and a more curved basal arch. Linear measurements yielded low correlations with muscle CSAs. In conclusion, this study demonstrates an association between mandibular muscle force and mandibular shape, which is not as readily identified from linear measurements. Retrodiction of masticatory muscle force and so of mandibular loading is therefore best based on overall mandibular shape

Review of nanomaterials in dentistry: interactions with the oral microenvironment, clinical applications, hazards, and benefits.

Interest in the use of engineered nanomaterials (ENMs) as either nanomedicines or dental materials/devices in clinical dentistry is growing. This review aims to detail the ultrafine structure, chemical composition, and reactivity of dental tissues in the context of interactions with ENMs, including the saliva, pellicle layer, and oral biofilm; then describes the applications of ENMs in dentistry in context with beneficial clinical outcomes versus potential risks. The flow rate and quality of saliva are likely to influence the behavior of ENMs in the oral cavity, but how the protein corona formed on the ENMs will alter bioavailability, or interact with the structure and proteins of the pellicle layer, as well as microbes in the biofilm, remains unclear. The tooth enamel is a dense crystalline structure that is likely to act as a barrier to ENM penetration, but underlying dentinal tubules are not. Consequently, ENMs may be used to strengthen dentine or regenerate pulp tissue. ENMs have dental applications as antibacterials for infection control, as nanofillers to improve the mechanical and bioactive properties of restoration materials, and as novel coatings on dental implants. Dentifrices and some related personal care products are already available for oral health applications. Overall, the clinical benefits generally outweigh the hazards of using ENMs in the oral cavity, and the latter should not prevent the responsible innovation of nanotechnology in dentistry. However, the clinical safety regulations for dental materials have not been specifically updated for ENMs, and some guidance on occupational health for practitioners is also needed. Knowledge gaps for future research include the formation of protein corona in the oral cavity, ENM diffusion through clinically relevant biofilms, and mechanistic investigations on how ENMs strengthen the tooth structure

Distinctive features of the microbiota associated with different forms of apical periodontitis

Microorganisms infecting the dental root canal system play an unequivocal role as causative agents of apical periodontitis. Although fungi, archaea, and viruses have been found in association with some forms of apical periodontitis, bacteria are the main microbial etiologic agents of this disease. Bacteria colonizing the root canal are usually organized in communities similar to biofilm structures. Culture and molecular biology technologies have demonstrated that the endodontic bacterial communities vary in species richness and abundance depending on the different types of infection and different forms of apical periodontitis. This review paper highlights the distinctive features of the endodontic microbiota associated with diverse clinical conditions

Biological Tissue Response to a New Formulation of a Silicone Based Endodontic Sealer

Satisfactory biological behavior is a necessary requirement for clinical application of endodontic materials. In this study, the connective tissue responses to silicone (GuttaFlow 2), epoxy resin (AH Plus) and zinc oxide and eugenol (Endofill) based sealers were compared. Twelve Wistar rats had polyethylene tubes (four per animal) containing one of the tested sealers and empty tubes (negative control) implanted in their subcutaneous tissue. The tubes were randomly placed 2 cm from the spine and at least 2 cm apart from one another. Tissue samples with implants were processed for histological analysis after 7 or 60 days (n=6 animals per period). Inflammatory cells, fibrous condensation and abscess were scored according to their intensity. Friedman, followed by Dunn’s post hoc, was used to compare sealers. Differences between the two experimental periods were verified using Mann-Witney U test (p<0.05). At 7 days, most of the histological parameters showed no significant differences amongst groups. Endofill group scored higher than the others for giant cells (o<0.05) and promoted a greater number of samples presenting abscess formation. GuttaFlow 2 tended to show a less intense inflammatory infiltrate compared to the other materials. At 60 days, there were no significant differences between groups in most of the histological parameters evaluated. However, it was observed that Endofill scored higher for macrophages (p<0.05) compared to the control group, and GuttaFlow 2 tended to present lower scores than the others for neutrophils and abscess. GuttaFlow 2 showed proper biological behavior and should be considered adequate for clinical practice