Micron and submicron scale parameters affecting the adhesion of resin composites to dental glass ceramics

The adhesion properties of the ceramic restorations play a crucial role in the overall performance and success rate of the treatment. Adhesion is required between the resin cement and tooth substance and indirectly made restoration. The aim of this laboratory study was to investigate the effect of some factors which relate to the bond (adhesion) strength. The study parameters included: 1. The effect of acid etching duration on the surface topography, roughness and wettability 2. The effect of surface neutralization on the wettability of silanes (silane coupling agents), adhesive resin and resin composite cement 3. The degree of resin impregnation into the etched micro-patterns 4. The nano-mechanical properties of the resin-ceramic interface 5. The ceramic-luting cement adhesion (shear bond) strength and 6. The effect of provoked degradation of the interface by exposure to boiling water on nano-mechanical properties and the adhesion strength. Silica based glass ceramics were selected and etching was done with 5% hydrofluoric acid and conditioning was done with two silane coupling agents (experimental and commercial silane coupling agents). Various combinations of silane coupling agents and resin cements were evaluated. Results were statistically analyzed with analysis of variance (ANOVA), the post hoc Tukey’s test, and regression analysis. Etching results showed a significant change in the surface topography and, increase in surface roughness, and wettability with increased etching duration. Neutralizing the ceramic surface did not show significant effect on wettability of silanes and, adhesive resin and resin composite cement. A combination of primer treatment and application of adhesive resin not only showed better resin impregnation into the etched micro-pores but also had high nano-hardness, modulus of elasticity, and adhesion (shear bond) strength

Malocclusion Pattern (Angle's) in Mauritian Orthodontic Patients

The aim of the study was to assess the pattern of malocclusion in different ethnic group of Mauritian population visiting the Orthodontic Department at Mauras College of Dentistry and Hospital, Republic of Mauritius. The study population comprised of 624 patients who visited the orthodontic department during 2010. The clinical examination was conducted by a well-calibrated orthodontist. The data were recorded in the case sheets and was analyzed for presence of angles class I, class II, and class III malocclusion in both male and female patients of Asian, African, Caucasian, and Chinese ethnicity aged 5–55 years. Malocclusion was found to be high in females compared to males. 414 patients (150 male + 264 female) presented with class I, 182 patients (52 male + 130 female) presented with class II, and 28 patients (12 male + 16 female) presented with class III. Asian ethnic group were more affected and patient seeking orthodontic treatment was high in 11–15 years age group

Dual-curing resin cement with colour indicator for adhesively cemented restorations to dental tissues: Change of colour by curing and some physical properties

The study was aimed to investigate a color indicator containing dual curing resin composite luting cement and to plot the color change to the time of solidification of the cement. In addition some physical properties were studied. Specimens were made of a dual-cure resin cement (Maxcem Elite™ Chroma, Kerr, Orange, CA, USA) and polymerized by autopolymerization only, or with light initiated polymerization. A spectrophotometer was used to quantify the color change of the cement as plotted with the curing time. The efficacy of the curing process was studied by measuring water sorption and the ultimate flexural properties of the cement. The results showed that the flexural strength of cement after autopolymerization was 27.3 MPa and after light initiated polymerization 48.1 MPa. Young's modulus of bending was 2089.3 MPa and 3781.5 MPa respectively for the same cement samples. Water sorption after two weeks for the autopolymerization cement samples was -1.12 wt% and for the light initiated polymerization samples 0.56 wt%. Non-parametric Spearman's correlation was measured for autopolymerized cement samples between variables for color and solidification load (N), which showed a strong correlation between curing process and color change (p < 0.05). There was a correlation between the color change and degree of monomer conversion of the dual curing resin composite luting cement which contained a color indicator system for polymerization reaction. The study also suggested that autopolymerization only resulted in suboptimal polymerization of the cement. By additional light curing considerably higher flexural properties were obtained.</p

Oralne manifestacije u pedijatrijskih bolesnika zaraženih virusom humane imunodefi cijencije na antiretrovirusnoj terapiji i bez nje: presječno istraživanje

The aim of the study was to assess and compare oral manifestations of human immunodefi ciency virus (HIV) infected pediatric patients undergoing antiretroviral therapy (ART) and those not undergoing ART. A cross sectional study included HIV positive children (receiving and not receiving ART) aged 5-15 years, registered at the District Hospital ART Centre, Udaipur, and HIV negative schoolchildren. HIV related oral lesions were diagnosed according to the World Health Organization criteria. Sociodemographic and other related information were also recorded. CD4+ cell count was determined in all study subjects. The χ2 -test, stepwise multiple linear regression and logistic regression were used on statistical analysis. In all tests, confi dence interval and p-value were set at 95% and ≤0.05, respectively. A greater proportion of HIV patients receiving treatment had CD4+ cell count of more than 750 cells/mm3 . The majority of HIV patients receiving ART for more than three years and only 20% of those not receiving ART were free from any oral lesions. The results of the present study demonstrated ART to be eff ective in reducing the prevalence of HIV related oral lesions, as already described in the literature; however, unlike previous studies, the present paper reports more valid fi ndings for having included most of the confounding variablesCilj istraživanja bio je procijeniti i usporediti oralne manifestacije u pedijatrijskih bolesnika zaraženih virusom humane imunodefi - cijencije (HIV) koji primaju antiretrovirusnu terapiju (ART) i onih koji ne primaju ovu terapiju. Ovo presječno istraživanje uključilo je HIV pozitivnu djecu (djecu koja primaju ART i djecu koja ne primaju ART) u dobi od 5-15 godina, registriranu pri Centru za ART u Pokrajinskoj bolnici u Udaipuru te HIV negativnu školsku djecu. Oralne promjene povezane s HIV-om dijagnosticirane su prema kriterijima Svjetske zdravstvene organizacije. Prikupljeni su socio-demografski te ostali podaci za svu djecu uključenu u ispitivanje. U svih je određen broj CD4+ stanica. U statističkoj analizi primijenjen je χ2 -test te postupna višestruka linearna regresija i logistička regresija. U svim testovima interval vjerodostojnosti i vrijednost p utvrđeni su na razini od 95% odnosno ≤0,05. Broj CD4+ stanica veći od 750 stanica/mm3 zabilježen je u većem postotku HIV bolesnika na ART. Bez oralnih promjena bila je većina HIV bolesnika koji su primali ART duže od tri godine, ali samo 20% onih koji nisu primali ART. Rezultati ovoga istraživanja pokazuju da ART učinkovito snižava učestalost oralnih promjena povezanih s HIV-om, što je već prije opisano u literaturi. Međutim, za razliku od prijašnjih ispitivanja, nalazi prikazani u ovom radu imaju veću vrijednost, jer uključuju većinu čimbenika koji bi mogli utjecati na rezultate

Photoactivated disinfection (PAD) of dental root canal system – An ex-vivo study

AbstractAimTo investigate the efficacy of photo activated disinfection (PAD) in reducing colony-forming unit (CFU) counts of Enterococcus faecalis (E. faecalis) in infected dental root canals. The study compared the efficacy of PAD with conventional endodontic treatment (CET) and also a combination of CET along with PAD.Material and Methods53 maxillary incisors were taken for the study. Teeth were divided into 3 groups, CET (Group I) (n=11), PAD (Group II) (n=21), and a combination of CET and PAD (Group III) which consisted of (n=21) samples, Group II and Group III were further divided into 2 subgroups, Group IIa, IIb and Group IIIa, IIIb. Strains of E. faecalis were inoculated in all the root canals. CET group samples were treated by chemo-mechanical preparation (CMP) alone, PAD samples were treated with laser alone at 2 different exposure time (4min and 2min). In the combination treatment, samples were treated initially by CET and then by PAD for a time period of 4min and 2min. Contents of the root canal were aspirated, diluted and plated in Tryptone Soya Broth (TSB) and plates were incubated for 24h to observe the bacterial regrowth.ResultsShowed PAD used along with CMP reduced the bacterial load of E. faecalis by 99.5% at 4min and 98.89% at 2min.ConclusionPAD may be an adjunctive procedure to kill residual bacteria in the dental root canal systems after standard endodontic root canal preparation

Influence of Monomer Systems on the Bond Strength Between Resin Composites and Polymerized Fiber-Reinforced Composite upon Aging

Purpose: This study examined the influence of different monomer systems on the tensile bond strength between a resin composite and a polymerized fiber-reinforced composite (FRC). The influence of the age (shelf-life) of the FRC prepreg (reinforcing fiber pre-impregnated with a resin system) before preparing the FRC substrate for the bonding test was also assessed.Materials and Methods: Semi-interpenetrating polymer network (semi-IPN)-based glass FRC prepregs were aged for various durations (1, 1.5, and 3 years) at 4 degrees C before being used to prepare FRC substrates via light polymerization. Four groups of aged prepregs were prepared through different treatments with: 1. no primer; 2. a dimethacrylate-based adhesive primer; 3. a universal primer; and 4. a specific composite primer. Subsequently, a resin composite luting cement was applied on the treated FRC substrates and cured with light. The water sorption of the FRC-composite specimens was determined. Then, the differences in the tensile bond strength were evaluated using ANOVA (p <= 0.05).Results: There were significant differences in the tensile bond strength between the composite cement and the FRC according to the primer used (p < 0.001), aging time (p < 0.001), and their interactive effect (p < 0.001).Conclusion: The monomers of the universal primer demonstrated the best ability to diffuse into the semi-IPN structure of the polymer matrix of FRC. This improved the interfacial bond strength between the composite cement and the FRC substrate

The effect of ethanol on surface of semi-interpenetrating polymer network (IPN) polymer matrix of glass-fibre reinforced composite

Aim of the study:The aim of this laboratory study was to evaluate the effect of ethanol treatment on the surfaceroughness (Sa), nano-mechanical properties (NMP) and surface characterization of dentalfiber reinforcedcomposite (FRC) with semi-interpenetrating polymer network (IPN).Materials and methods:A total of 240 FRC specimens with bisphenol A-glycidyl methacrylate - triethyleneglycoldimethacrylate–Poly (methylmetahcrylate) (bis-GMA-TEGDMA-PMMA) IPN matrix system were light cured for40 s and divided into 2 groups (L and LH). The group LH was further post-cured by heat at 95 °C for 25 min. Thespecimens were exposed to 99.9%, 70% and 40% for 15, 30, 60 and 120 s respectively. The treated specimenswere evaluated for Sausing non-contact profilometer. NMP were determined using nanoindentation techniqueand chemical characterization was assessed by Fourier Transform-Infrared (FTIR) spectroscopic analyses.Scanning electron microscopic (SEM) images were made to evaluate the surface topographical changes.Results:Both the L and LH group showed changes in the Saand NMP after being treated by different con-centrations of ethanol and at different time interval. The highest Sawas observed with L-group (0.733μm)treated with 99.9% ethanol for 120 s. Specimens in LH-group treated with 99.9% ethanol for 120 s (1.91 GPa)demonstrated increased nano-hardness, and group treated with 40% ethanol for 120 s demonstrated increasedYoung's modulus of elasticity (22.90 GPa). FTIR analyses revealed changes in the intensity and bandwidth inboth the L and LH groups.Conclusion:The present study demonstrated that both light-cured and heat post-cured FRC were prone forethanol induced alteration in the surface roughness (Sa), nano-mechanical properties (NMP) and chemicalcharacterization. The interphase between the glassfibers and the organic matrix was affected by ethanol. Thechanges were considerably less in magnitude in the heat post-cured FRC specimens.</p

Preliminary fabrication and characterization of electron beam melted Ti–6Al–4V customized dental implant

The current study was aimed to fabricate customized root form dental implant using additive manufacturing technique for the replacement of missing teeth. The root form dental implant was designed using GeomagicTM and MagicsTM, the designed implant was directly manufactured by layering technique using ARCAM A2TM electron beam melting system by employing medical grade Ti–6Al–4V alloy powder. Furthermore, the fabricated implant was characterized in terms of certain clinically important parameters such as surface microstructure, surface topography, chemical purity and internal porosity. Results confirmed that, fabrication of customized dental implants using additive rapid manufacturing technology offers an attractive method to produce extremely pure form of customized titanium dental implants, the rough and porous surface texture obtained is expected to provide better initial implant stabilization and superior osseointegration

Occurrence of vancomycin-resistant Staphylococcus aureus in the oral cavity of patients with dental caries

Oral streptococci are the major group of microbes isolated from oral microflora. They represent frequent pathogens of infective endocarditis (IE), and it is assumed that in most of the cases oral streptococci are acquired via mucosa layer of oral cavity. Staphylococcus aureus is also frequently isolated from IE as it accounts for 20%–30% of all cases. Vancomycin has been the most reliable therapeutic agent against infections caused by methicillin-resistant S. aureus (MRSA). The main objective of this study was to examine the occurrence of S. aureus species in dental caries specimens. Antimicrobial susceptibility testing of S. aureus to four antibiotics namely vancomycin, linezolid, teicoplanin, and daptomycin was performed. Detection of vancomycin resistance was conducted using polymerase chain reaction. Among the tested 150 strains, 98 were MRSA and of that 54 were vancomycin sensitive and 27 were resistant. All 98 MRSA strains were positive for mecA and 36 yielded pvl, whereas 13 carried vanA and only 2 were positive for vanB. Majority of the isolates showed sensitivity toward daptomycin and linezolid. Strains of S. aureus exhibiting decreased susceptibility to different antibiotics like vancomycin, daptomycin, and linezolid severely compromise the therapeutic alternatives and require a considerable amount of time, public awareness, and integrative health-care strategies to prevent the emergence of resistance to these compounds

Applications of raman spectroscopy in dentistry part II: Soft tissue analysis

Raman spectroscopy is rapidly moving from an experimental technique for the analysis of biological molecules to a tool for the real-time clinical diagnosis and in situ evaluation of the oral tissue in medical and dental research. The purpose of this study is to identify various applications of Raman spectroscopy, to evaluate the contemporary status and to explore future directions in the field of dentistry. Several in-depth applications are presented to illustrate Raman spectroscopy in early diagnosis of soft tissue abnormalities. Raman spectroscopy allows to analyze histological and biochemical composition of biological tissues. The technique not only demonstrates its role in the disclosure of dysplasia and malignancy but also in performing guided biopsies, diagnosing sialoliths, and assessment of surgical margins. Raman spectroscopy is used to identify the molecular structures and its components to give substantial information about the chemical structure properties of these molecules. In this paper, we acquaint the utilization of Raman spectroscopy in analyzing the soft tissues in relation to dentistry