Non‐stick properties of thin‐film coatings on dental‐restorative instruments

The non‐stick properties of thin‐film coatings on dental‐restorative instruments were investigated by static contact‐angle measurement using dental filler resin as well as by scanning electron microscopy of the amount of sticking dental restorative material. Furthermore, using a customized dipping measurement set‐up, non‐stick properties were evaluated by measuring force‐by‐time when the instrument was pulled out of restorative material. Minor improvements in non‐stick properties were obtained with commercial diamond‐like carbon and commercial polytetrafluoroethylene‐based coatings. Major improvements were obtained with an in‐house fabricated superhydrophobic coating prepared by a multistep process consisting of surface microstructuring by etching in hydrogen fluoride (HF): hydrogen peroxide (H₂O₂) (1:1; vol/vol), atomic layer deposition of a 7 nm coating of aluminium oxide and titanium oxide, and a self‐assembled monolayer of fluorinated organosilicon. Superhydrophobic coatings provide a possible future solution to prevent unwanted adnerence of composite restorative material to dental instruments.     

Effect of Dycal® on dentin permeability

Abstract The ability of 3 formulations of a hard-setting calcium hydroxide-containng base material (Dycal®) to seal dentinal tubules was evaluated in an in vitro model. The latest light-cured generation of the material was clearly superior to the previous formulations at all time periods tested.     

Bacterial colonization on internal surfaces of Brånemark system® implant components

The aim of the present study was to examine the microbiota on the internal surface of the components of 28 Brånemark implants® in 10 partially edentulous patients who had been treated with 1 fixed partial prostheses each. The prostheses had been in function for 1 to 8 years. The fixed prostheses were checked for mobility and removed. The abutment screws were loosened and classified as stable, easily removed or loose. Then, bacterial samples were obtained from the various internal surfaces of the implant system. Estimation and identification of the most predominant species was performed on the blood agar plates. Identification was based on Gram reaction, oxygen sensitivity and biochemical tests. Internal surfaces of different components of the Brånemark implants®, after varying periods of function in the oral cavity, consistently harboured a heterogeneous and primarily anaerobic microbiota. The individual samples showed a great variation. No relation could be seen between type and length of abutment, abutment stability, bone loss and type and number of microorganisms found in the samples. The flora consisted mainly of facultative and anaerobic streptococci, Gram‐positive anaerobic rods such as Propionibacterium, Eubacterium and Actinomyces species and Gram‐negative anaerobic rods including Fusobacterium, Prevotella and Porphyomonas species. There are reasons to suggest that this presence of bacteria is the result of (i) a contamination of the fixture and abutment components during the 1st and/or 2nd stage of implant installation and/or (ii) a transmission of microorganisms from the oral environment during function subsequent to bridge installation.     

Effects of three γ‐alkylidene‐γ‐lactams on the formation of multispecies biofilms

This study evaluated the inhibitory effects of lactams on Streptococcus mutans, Enterococcus faecalis, and Candida glabrata multispecies biofilm formation. γ‐Alkylidene‐γ‐lactams 1, 2, and 3 [solubilized in 3.5% dimethyl sulfoxide (DMSO)] were tested. Glass coverslips were conditioned with either the lactams or 3.5% DMSO (control) for 1 h, inoculated with microbial cultures, and incubated for 48 h. To assess the effect of the lactams on biofilm formation, the following parameters were determined: the biofilm biomass (by both crystal violet staining and protein determination); the amount of insoluble polysaccharides of the extracellular matrix; and the number of viable and total cells [by both colony‐forming unit counting and quantitative real‐time PCR (qPCR)]. Data were analysed using one‐way anova and post‐hoc Tukey tests. Lactams 1, 2, and 3 promoted a statistically significant reduction in the amount of biofilm biomass, but only lactam 3 resulted in a statistically significant reduction in the number of attached viable E. faecalis. Both total protein content and the amount of extracellular polysaccharides decreased significantly. The effects of γ‐alkylidene‐γ‐lactams 1, 2, and 3 on the inhibition of multispecies biofilm formation were evident by their ability to reduce the amount of protein and extracellular polysaccharides.     

The use of a ‘bleach‐etch‐seal’ deproteinization technique on MIH affected enamel

International Journal of Paediatric Dentistry 2012; 22: 427–434 Aims. To ascertain whether deproteinization pretreatment of molar‐incisor hypomineralization (MIH) enamel affects resin sealant infiltration. Design. Thirty one extracted MIH teeth were divided into three sections and randomly allocated into the Control (etch and FS), Treatment 1 (5% NaOCl, etched and fissure sealed), and Treatment 2 (5% NaOCl and fissure sealed with no etch) groups. Two hundred seventy nine sealant tag/enamel grade observations were recorded by scanning electron microscopy. Results. Control and Treatment 1 were similar in their outcomes, and Treatment 2 was markedly different. There was no statistical evidence to suggest that there was any difference between Treatment 1 and the Control Treatment (95% CI, 0.52, 1.51; P = 0.6). There was a marked difference between Treatment 2 and the Control Treatment (95% CI, 0.07, 0.25; P < 0.001). All treatments also demonstrated a high‐predicted probability of obtaining ‘poor’ sealant tags (Control = 47%, Treatment 1 = 49%, and Treatment 2 = 40%). Conclusions. The findings suggest that there was no significant difference in the tag quality between the conventional technique (Control) and the ‘bleach‐etch‐seal’ technique (Treatment 1). There was no benefit in pre‐treating with NaOCl alone (without etch) before sealing. This research also showed that there was a high‐predicted probability of obtaining ‘poor’ sealant tags in MIH enamel, regardless of which of the three treatments was used.     

Perspectives on next steps in classification of oro‐facial pain – part 2: role of psychosocial factors

This study was initiated by a symposium, in which the present authors contributed, organised by the International RDC/TMD Consortium Network in March 2013. The purpose of the study was to review the status of biobehavioural research – both quantitative and qualitative – related to oro‐facial pain (OFP) with respect to the aetiology, pathophysiology, diagnosis and management of OFP conditions, and how this information can optimally be used for developing a structured OFP classification system for research. In particular, we address representation of psychosocial entities in classification systems, use of qualitative research to identify and understand the full scope of psychosocial entities and their interaction, and the usage of classification system for guiding treatment. We then provide recommendations for addressing these problems, including how ontological principles can inform this process.     

Some effects of Ledermix® paste and Pulpdent® paste on mouse fibroblasts and on bacteria in vitro

Abstract Dilutions of Ledermix® paste, Pulpdent® paste and a mixture of equal parts by weight of Ledermix paste and Pulp-dent paste were added to in vitro cultures of mouse fibroblasts or bacteria for 24 h, and various cell functions were then examined: mitosis in and survival of fibroblasts, and survival of Lactobacillus casei or Streptococcus mutans. Ledermix was found to reversibly inhibit mitosis while present in the concentrations range 10^?3 to 10^?6 mg/ml. Mixing with Pulpdent did not modify this antimitotic effect. Ledermix killed mouse fibroblasts at 10^?3 mg/ml and above, while Pulpdent killed at 1 mg/ml and above. The toxic effect of Ledermix was slightly inhibited by mixing it with Pulpdent. Ledermix killed S. mutans at about the same concentration at which it killed the mammalian cells, but required a one thousand-fold greater concentration to kill L. casei. Pulpdent killed both L. casei and S. mutans at approximately one-fifth of the concentration at which it killed the mammalian cells. Pulpdent slightly potentiated the antibacterial effect of Ledermix. The pH of Pulpdent was reduced by approximately 0.3 units by mixing with Ledermix. The present data showed that the 50:50 mix of Ledermix and Pulpdent retained the properties examined that are thought to be of therapeutic benefit, while not increasing the toxicity of the component parts to mammalian cells.     

Effect of CO<Subscript>2</Subscript> laser irradiation on wound healing of exposed rat pulp

This study examined the effects of direct pulp capping treatment using super-pulsed CO₂ laser preirradiation on the wound healing process of exposed rat pulp on days 1, 3, 7, 14, and 28 postoperatively. Group 1 was irradiated with a CO₂ laser and directly capped with a self-etching adhesive system. The laser was operated in super-pulse mode (pulse duration, 200 μs; interval, 5800 μs; 0.003 J/pulse). The irradiation conditions were a power output of 0.5 W, an irradiation time of 3 s, and repeat mode (10 ms of irradiation at 10-ms intervals for a total beam exposure time of 1.5 s), defocused beam diameter of 0.74 mm (approximately 20 mm from the exposed pulp surface), energy density of 0.698 J/cm² per pulse, total applied energy of 0.75 J, and an activated air-cooling system. Group 2 was capped with the self-etching adhesive system. Group 3 was capped with commercially available calcium hydroxide, and the self-etching adhesive system was applied to the cavity. The following parameters were evaluated: pulp tissue disorganization, inflammatory cell infiltration, reparative dentin formation, and bacterial penetration. The results were statistically analyzed using the Kruskal-Wallis test for differences among the groups at each observation period (P < 0.05). There were no significant differences among the experimental groups in any parameters at any postoperative period (P > 0.05). CO₂ laser irradiation was effective in arresting hemorrhaging but showed a tendency to delay reparative dentin formation compared with the application of calcium hydroxide.     

More on “definition and scope of orthodontics”

A modification of the Moorrees mesh diagram analysis takes advantage of the same basic principles and provides the same interpretation as the originally described analysis. In addition, linear and angular measurements may be assessed and compared with the individualized norm drawn through the analysis inherent to the mesh diagram. This modification is particularly useful for planning surgical correction of facial dysmorphology in that an individualized norm for a patient serves as a graphic guide for assessment of the specific characteristics of the patient's face and the correction required to achieve harmonious facial relationship.     

Efficacy of stabilisation splint treatment on the oral health‐related quality of life–A randomised controlled one‐year follow‐up trial

The aim of this randomised controlled trial was to assess the efficacy of stabilisation splint treatment on the oral health‐related quality of life OHRQoL during a 1‐year follow‐up. Originally, the sample consisted of 80 patients (18 men, 62 women) with temporomandibular disorders (TMD) who had been referred to the Oral and Maxillofacial Department, Oulu University Hospital, Finland, for treatment. Patients were randomly designated into splint (n = 39) and control group (n = 41). Patients in the splint group were treated with a stabilisation splint. Additionally, patients in both groups received counselling and instructions on masticatory muscle exercises. The patients filled in the Oral Health Impact Profile‐14 (OHIP‐14) questionnaire before treatment and at 3 months, 6 months and 1 year. At total, 67 patients (35 in the splint group vs. 32 in the control group) completed the questionnaire at baseline. The outcome variables were OHIP prevalence, OHIP severity and OHIP extent. Linear mixed‐effect regression model was used to analyse factors associated with change in OHIP severity during the 1‐year follow‐up, taking into account treatment time, age, gender and group status. OHIP prevalence, severity and extent decreased in both groups during the follow‐up. According to linear mixed‐effect regression, decrease in OHIP severity did not associate significantly with group status. Compared to masticatory muscle exercises and counselling alone, stabilisation splint treatment was not more beneficial on self‐perceived OHRQoL among TMD patients over a 1‐year follow‐up