Clinical reproducibility of three electronic apex locators

Though it is not quite a dental materials subject, I have been involved in clinical testing of electronic apex locators with my colleagues at the University of Belgrade School of Dentistry. This paper has been published in the August issue of the International Endodontic Journal and can be found here. If you have trouble getting access, please email me.
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Miletic V, Beljic-Ivanovic K, Ivanovic V. Clinical reproducibility of three electronic apex locators. International Endodontic Journal, 44, 769–776, 2011.

Abstract

Aim  To compare the reproducibility of three electronic apex locators (EALs), Dentaport ZX, RomiApex A-15 and Raypex 5, under clinical conditions.

Methodology  Forty-eight root canals of incisors, canines and premolars with or without radiographically confirmed periapical lesions required root canal treatment in 42 patients. In each root canal, all three EALs were used to determine the working length (WL) that was defined as the zero reading and indicated by ‘Apex’, ‘0.0’ or ‘red square’ markings on the EAL display. A new K-file of the same size was used for each measurement. The file length was fixed with a rubber stop and measured to an accuracy of 0.01 mm. Measurements were undertaken by two calibrated operators. Differences in zero readings between the three EALs in the same root canal were statistically analysed using paired t-tests with the Bonferroni correction, Bland–Altman plot and Linn’s concordance correlation coefficients at α = 0.05.

Results  Mean and standard deviation values measured by the three EALs showed no statistically significant differences. Identical readings by all three EALs were found in 10.4% of root canals. Forty-three per cent of readings differed by less than ±0.5 mm and 31.3% exceeded a difference of ±1 mm.

Conclusions  The clinical reproducibility of Dentaport ZX, RomiApex A-15 and Raypex 5 was confirmed with the majority of readings within the ±1.0 mm range. However, the small number of identical zero readings suggests that EALs are not reliable as the sole means of WL determination under clinical conditions.

Upcoming event: CED IADR 2011

The 45th Meeting of the Continental European Division (CED) of IADR, organized together with the Scandinavian Division (NOF) will be held in Budapest, Hungary, from August 31 till September 3, 2011. Basic sciences and clinical topics, such as dental materials, cariology, implantology, periodonontology, oral medicine, tissue engineering, craniofacial biology, salivary research etc. will be covered by plenary lectures, symposia, oral and poster presentation sessions etc.

Scientific symposia on dental materials will cover the following subjects:

1. Adhesive technology
2. Needs and requirements of dental materials in combating caries 
3. Biomaterials in periodontal and implant surgery
4. Aesthetic and mechanical aspects of composite materials
5. Implant restoration
6. Nano biomaterials in regenerative dentistry
7. Novel tri-calcium silicate-based dentine substitute

I will present a digital image correlation study on composite shrinkage using a two-camera system which allows 3D measurement of strains and displacements. This study is a result of strengthening research ties between my team from the School of Dentistry and colleagues from the Faculty of Mechanical Engineering, University of Belgrade, Serbia. The abstract of this study is here. Also, other studies that will be presented during the same session on Composites, Shrinkage, Curing, and Fracture Toughness may be found here.

For more information on the scientific programme and registration for the 45th IADR CED&NOF conference please visit the official CED-IADR2011 website.

IADR Toshio Nakao Fellowship

The 89th General Session of the International Association for Dental Research was held last week in San Diego, CA, USA. I was officially awarded the IADR Toshio Nakao Fellowship during the opening ceremony. This Fellowship is generously supported by GC Corporation with the intention to "allow a young investigator to obtain training and experience in dental materials science at a center of excellence". In my case, this means six months post-doctoral research at the University of Edinburgh, Great Britain, commencing in June 2011. It was truly an honour to be among the distinguished scientists whose work has been recognized by the IADR, the leading international organisation in dental research. I am grateful to the IADR and GC Corporation for support. This Fellowship will help me continue research on dental adhesives, particularly monomer to polymer conversion and hybridisation of dentine.

A review of SEM and TEM studies on the hybridisation of dentine

Professors Ario Santini and Egle Milia and Dr Vesna Miletic, members of the Santini Miletic Research Group, published a chapter on dentine hybridisation in the international peer-reviewed book Microscopy: Science, Technology, Applications and Education, edited by A. Mendez-Vilas and J. Diaz and published by Formatex (www.formatex.org). This is the 4th book in the Microscopy series. The chapter is a review of SEM and TEM studies on the hybridisation of dentine with additional findings on the subject using micro-Raman spectroscopy. The chapter can be downloaded free of charge from the publisher's website
http://www.formatex.org/microscopy4/chapters1.html (simply scroll down to Santini, Milia and Miletic).

Santini A, Egle M and Miletic V. A review of SEM and TEM studies on the hybridisation of dentine.
In: Microscopy: Science, Technology, Applications and Education.
Editors: Mendez-Vilas A, Diaz J. Microscopy series No. 4, Volume 1, pages 256-268.       
Publisher: FORMATEX, Badajoz, Spain, 2011.
ISBN-13: 978-84-614-6189-9

Abstract

Current opinion is that the hybridisation of dentine is the principal, though not the exclusive, mode of adhesion of restorations to tooth tissue. Hybrid layer formation is achieved by resin infiltration of acid-etched dentine. This layer provides micromechanical retention for resin composite restorations.

The vast literature on the development of bonding systems is summarised and the differences in the hybrid layer formation are reviewed with specific attention to SEM and TEM studies.

It is concluded that more recently marketed adhesives with simplified application procedures are less successful compared to conventional total-etch adhesives.

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Visit santinimiletic.com for more references of our research group.

Monomer elution from nanohybrid and ormocer-based composites

Recently, a paper on monomer elution from resin-based composites by my research team has been accepted for publication in the leading peer-reviewed journal on dental materials. The paper is available online under "Articles in press" and awaits publication in the paper format of Dental Materials. For reprints, you may contact me at vesna.miletic@gmail.com 

Abstract

Dent Mater. 2010 Dec 17. [Epub ahead of print]

Monomer elution from nanohybrid and ormocer-based composites cured with different light sources

Manojlovic D, Radisic M, Vasiljevic T, Zivkovic S, Lausevic M, Miletic V.

University of Belgrade, School of Dentistry, Department of Restorative Dentistry
and Endodontics, Rankeova 4, 11000 Belgrade, Serbia.

OBJECTIVES: To study monomer elution from four resin-based composites (RBCs)cured with different light sources.  
METHODS: Twenty-eight premolars were randomlyallocated to four groups. Standardized cavities were prepared and restored with ananohybrid (Filtek Supreme XT or Tetric EvoCeram), an ormocer (Admira) or a microhybrid RBC (Filtek Z250) which served as control. Buccal restorations were cured with a halogen and oral restorations with an LED light-curing unit. Elution of diurethane dimethacrylate (UDMA), Bisphenol A diglycidylether methacrylate (BisGMA), triethylene glycol dimethacrylate (TEGDMA) and 2-hydroxyethyl methacrylate (HEMA) was analyzed using high-performance liquid chromatography (HPLC) 1h to 28 days post-immersion in 75% ethanol. Data were analyzed using multivariate and repeated measures analysis of variance (α=0.05).  
RESULTS: The greatest elution of UDMA and BisGMA occurred from Tetric EvoCeram and the least from Filtek Z250 (p<0.05). LED and halogen light-curing units gave similar results for all RBCs (p>0.05) except Tetric EvoCeram which showed greater elution for the LED unit (p<0.05). TEGDMA was below the limit of quantification. HEMA eluted in similar concentrations from Filtek Supreme and Tetric EvoCeram (p>0.05).  
SIGNIFICANCE: The two nanohybrid RBCs eluted more cross-linking monomers than the ormocer and the control microhybrid RBC. Continuous elution over 28 days indicates that RBCs act as a chronic source of monomers in clinical  conditions. Light source may affect monomer elution since differences were found  for one out of four RBCs. Mathematical models for elution kinetics of UDMA and BisGMA indicated two elution mechanisms.

Silorane technology in restorative dentistry - material properties and clinical application

I recently published a review article in the Serbian professional journal "Stomatolog" ["Dentist"] on Filtek Silorane material properties and clinical application steps. The article is in Serbian but I would be happy to translate it to English for interested colleagues. Contact me at vesna.miletic@gmail.com

Abstract

Polymerization shrinkage remains one of the main weaknesses of composite materials. Silorane technology significantly reduces material shrinkage compared to methacrylate composites. This review article compares chemical composition and polymerization process of methacrylate- and silorane-based composites. Systematically are reviewed studies on mechanical, aesthetic, antibacterial and chemical properties of Filtek Silorane, as well as its interaction with tooth tissues. Lower polymerization shrinkage and microbial adherence and comparable mechanical properties have been reported for Filtek Silorane compared to methacrylate-based composites. In the only clinical study that has been published so far, marginal adaptation of Filtek Silorane was found to be inferior than the nanocomposite Ceram.X  However, low inter-examiner reliability questions the results of this clinical study and scientific literature lacks more information on clinical performance of Filtek Silorane. 

Monomer elution from a dental composite

Recently, I started a series of studies on monomer elution from composites with colleagues from University of Belgrade School of Dentistry and Faculty of Technology and Metallurgy. One of these experiments was presented a month ago at an international material science and engineering conference YUCOMAT.

The nano-hybrid composite Filtek Z250 (3M ESPE) was used to study elution kinetics of monomers UDMA and HEMA over 28 days post-immersion in either distilled water or 75% ethanol. Kinetic models were proposed and it was shown that monomer elution followed the first order law for both UDMA and HEMA irrespective of the medium. However, there were some differences in that UDMA eluted more rapidly during the first 24 h and then much more slowly over the 28-day period. This indicates that during the first 24 h elution from the sample surface occurred whereas the slow phase corresponds to monomer elution from inside the polymer. On the other hand, HEMA did not start to elute immediately, but only after 24 h and the eluted concentrations increased over the 28 days. Though HEMA is not a genuine ingredient of the studied composite, its slow elution and small eluted amounts seem to support a previous statement by other authors that HEMA could elute as a product of degradation of UDMA. (We are currently investigating this hypothesis.)

Dental Materials Blog: Year 1

It has been a year since I started writing on this blog. During this first year, nearly 6700 visits and 12000 pageviews have been made by more than 5300 unique visitors. The average number of visits per day has been increasing constantly and currently is 17.70. What I am particularly proud is that one fifth of all visitors have returned and visited the blog more than once. Another important figure is that visitors come from more than 120 countries in the world (Figure 1.). The importance of this information is not so much related to the blog itself, but shows that in almost every corner of the Earth people search for dental information and want to expand their knowledge.

Figure 1. Map overlay

The most frequently visited posts are related to MTA in endodontics and the list of free full texts, self-adhering composite Vertise Flow and nano-filled, resin-modified glass ionomer Ketac N100. Likewise, the most frequently used keywords are "dental materials", ""MTA dental material", ""MTA dental", "mineral trioxide aggregate",  "Vertise Flow"...

Comments were disabled for most of the year, because I haven't noticed there was a problem, but a visitor drew my attention to it. Comments are now fixed and those received so far are all very positive.

I would like to encourage fellow researchers and clinicians to contribute to the Dental Materials Blog with their own posts, it is free and the choice of topics is entirely up to the authors.

Journal of Esthetic and Restorative Dentistry gets its first impact factor

A Miletic et al. study among the top 5 cited papers

In the latest list of SCI Journal Impact Factors 2009 published by Thomson Reuters, Journal of Esthetic and Restorative Dentistry is listed with the impact factor of 0.797. The Journal thanks all authors, reviewers and readers and allows free access to the top cited articles. Easy online submissions through ScholarOne Manuscripts are encouraged as this speeds up the review process. Hopefully, the Journal will maintain a growing influence in the scientific literature and increase its impact factor in the future.


It was a pleasure to see that one of the papers I did with my colleagues at the University of Belgrade School of Dentistry was among the top 5 cited articles in the Journal of Esthetic and Restorative Dentistry.

Miletic V, Ivanovic V, Dzeletovic B, Lezaja M.
Temperature Changes in Silorane-, Ormocer-, and Dimethacrylate-Based Composites and Pulp Chamber Roof during Light-Curing.

I look forward to submitting the results of my current studies to the Journal of Esthetic and Restorative Dentistry.

88th IADR General Session (Barcelona, 2010)

Effect of Preparation and Storage on Adhesive Monomer Conversion

V. MILETIC,  University of Belgrade, Belgrade, Serbia,  
A. SANTINI, The University of Edinburgh, Edinburgh, United Kingdom

Objectives: To study the effect of sample preparation and storage conditions on the degree of conversion (DC) of two adhesive systems using micro-Raman spectroscopy.  
Methods: Sixty samples each of an etch-and-rinse (Excite) and a self-etch (Clearfil 3S) adhesive were prepared on glass slides and allocated to groups G1-G6 (n=10). Thirty samples of each adhesive were prepared on dentine discs according to manufacturer's instructions and allocated to groups D1-D6 (n=5). In groups G1 and D1, each sample was covered with a Mylar strip and cured for 10 s with a bluephase LED unit. In groups G2 and D2, samples were cured without the Mylar strip. Micro-Raman spectra were taken 5 min post-curing. Groups G3-G6 and D3-D6 were covered with Mylar strips, cured according to the same protocol and stored for 24 h: G3 and D3 at 22±2ºC and 45±3% humidity; G4 and D4 at 37±1ºC and 90±2% humidity; G5 and D5 in distilled water at 37±1ºC; G6 and D6 in buffered incubation medium at 37±1ºC. Micro-Raman spectra were taken 5 min post-curing and after storage. Data were analyzed using t-tests and repeated measures ANOVA and the level of significance was α=0.05.
Results: Higher DC values were found on dentine than glass for both adhesives (p<0.05). Higher DC values were found for both adhesives when cured on dentine with than without Mylar strips (p<0.05). Higher DC values were found for Excite cured on glass with than without Mylar strips (p<0.05), but there was no difference for Clearfil 3S (p>0.05). Both adhesives cured on dentine gave higher DC after 24 h storage irrespective of the medium (p<0.05). Excite G3 group and Clearfil 3S G3 and G4 groups showed higher DC values after storage (p<0.05).
Conclusions: Sample preparation methods and storage conditions significantly affected the DC of Excite and Clearfil 3S.

IADR 2010

If you can't see this presentation, you should download Adobe Flash Player. It's free. Click here.

Research Methodology in Dentistry seminar

It will be my great honour to lecture again along side my supervisor, Dr Ario Santini, at a seminar on Research Methodology in Dentistry. The seminar will take place at Belgrade University School of Dentistry on Thursday, June 10 (9am-1pm). The seminar is accredited by the Serbian Health Council and each attendee gets 4 CE points.



Programme:

9-9.15 Opening remarks
9.15-9.45 Dr Vesna Miletic: Literature search (MEDLINE and KoBSON)
9.45-10.45 Dr Ario Santini: Designing a study protocol
10.45-11 Break
11-12 Dr Ario Santini: Writing a scientific article
12-12.30 Dr Vesna Miletic: Managing references with EndNote
12.30-1 pm Discussion and practical work

The seminar is free for professors and clinical lecturers of Belgrade School of Dentistry. Contact me at vesna.miletic@gmail.com  to reserve a seat.

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Filtek Silorane composite: temperature changes during light-curing

Some time ago, my colleagues and I published a paper on temperature changes during curing of Filtek Silorane, Admira (ormocer) and Herculite XRV (microhybrid, control) composites. It was interesting to notice substantially higher temperature rise in Filtek Silorane compared to the other two materials. However, there was no difference in the temperature rise inside the pulp chamber, probably due to the insulating effect of the remaining dentine.

The abstract of this paper may be found on MEDLINE and I will be happy to email the full text to anyone interested in this subject. Feel free to contact me at vesna.miletic@gmail.com

J Esthet Restor Dent 2009;21(2):122-31.
Temperature changes in silorane-, ormocer-, and dimethacrylate-based composites and pulp chamber roof during light-curing.
Miletic V, Ivanovic V, Dzeletovic B, Lezaja M.

STATEMENT OF THE PROBLEM: Light-curing of resin-based composites (RBCs) is associated with temperature increase in the pulp chamber, which may have a detrimental effect on the vital pulp.
PURPOSE: The purpose of the study was to evaluate temperature changes of silorane-, ormocer-, and dimethacrylate-based RBCs at the bottom surface of the RBC and in the pulp chamber roof dentin (PCRD) during curing.  
MATERIALS AND METHODS: In part A, temperatures were measured for Filtek LS (3M ESPE, St. Paul, MN, USA), Admira (Voco GmbH, Cuxhaven, Germany), and Herculite XRV (Kerr Corp., Orange, CA, USA) with a high-power light-emitting diode (LED) unit by placing thermocouples in contact with the bottom surface of the material in standardized acrylic molds. In part B, temperature changes in PCRD were measured in extracted molars during light-curing of adhesives and RBCs in 2-mm-deep cavities with a remaining dentin thickness (RDT) of 1 mm.
RESULTS: Filtek LS showed a different temperature curve compared with Admira and Herculite XRV. Significantly higher temperatures were recorded for Filtek LS (p < 0.001) than for Admira and Herculite XRV in acrylic molds. Temperature rises recorded in PCRD for adhesives and RBCs were between 4.1 and 6.4 degrees C. No significant differences in PCRD temperatures were found between the three groups during adhesive curing and RBC curing (p > 0.05).  
CONCLUSIONS: Filtek LS showed a different heat-generation pattern from and significantly higher temperatures than Admira and Herculite XRV when the materials were tested in acrylic molds. Similar temperatures were recorded in the PCRD during curing of adhesives and RBCs.
CLINICAL SIGNIFICANCE: Although a substantial temperature rise in the bulk material occurred during light-curing of the three resin-based composites, a remaining dentin thickness of 1 mm caused a significant reduction in pulp chamber roof dentin temperatures. Temperatures measured in the pulp chamber roof dentin corresponding to the zone occupied by the postmitotic odontoblast layer were not statistically different for the three types of resin-based composites.

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The effect of light source on monomer conversion of dental adhesives

The most recent paper by Santini Miletic research group will be published in Journal of Adhesive Dentistry, hopefully in the next issue. The abstract is available on PubMed/MEDLINE.

J Adhes Dent. 2009 Nov 27. doi: 10.3290/j.jad.a17855. [Epub ahead of print]

Micro-Raman Assessment of the Ratio of Carbon-Carbon Double Bonds of Two Adhesive Systems Cured with LED or Halogen Light-curing Units.

Miletic V, Santini A.

Purpose: The purpose of the study was to compare the ratio of carbon-carbon double bonds (RDB) of two adhesive systems cured by five different light-curing units (LCUs) using micro-Raman spectroscopy.
Materials and Methods: Ten samples of an etch-and-rinse (Excite), a two-step self-etching adhesive system (AdheSE) - ie, primer and bond mixed - and AdheSE Bond only were prepared and cured with one of the following LEDs: Elipar Freelight2; Bluephase; SmartLite; Coltolux, each for 10 s; or a conventional halogen Prismetics Lite for 10 s or 20 s. Micro-Raman spectra were obtained from uncured and cured samples of all three groups to calculate the RDB. Data were statistically analyzed using ANOVA.  
Results: The mean RDB values were 62% to 76% (Excite), 36% to 50% (AdheSE Primer+Bond) and 58% to 63% (AdheSE Bond). At 20 s, Prismetics Lite produced significantly higher RDB in Excite than the other LCUs and Prismetics Lite at 10 s (p < 0.05). Prismetics Lite at 20 s and Elipar produced comparable RDB values of AdheSE Bond and AdheSE Primer+Bond (p > 0.05). Excite showed significantly higher RDB values than AdheSE (p < 0.05) whilst AdheSE Bond showed significantly higher RDB than AdheSE Primer+Bond (p < 0.05).  
Conclusion: The etch-and-rinse adhesive cured with the halogen LCU for 20 s gave higher conversion than LED LCUs or halogen for 10 s curing time. The highest intensity LED [Elipar] produced higher or comparable conversion compared to the lower intensity LED LCUs for the same curing time. The etch-and-rinse adhesive showed higher RDB than the self-etching adhesive system. The presence of the primer in the self-etching adhesive compromised polymerisation.

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Summary

The end of the year is usually a period when many people like to summarise their achievements and make future plans. I've been using google analytics for slightly more than 3 months now. It's really great to be able to see the statistics about one's blog.

Dental-materials.blogspot.com had exactly 1000 visits between Sept 21 and Dec 25 from 72 countries/territories. The list of top 10 countries with the greatest number of visits includes the USA, India, Egypt, Germany, Indonesia, Canada, Turkey and Iran.




Of 702 absolute uniqe visitors, about one third were returning visitors with more than 300 visits :-) The average time on site was 00:02:26 with an average of 1.90 Pages/Visit.

More than half of all visits came through search engines, Google being the most popular, as expected. About the same number of visits came as direct traffic and from referring sites, such as blogger.com, twitter.com, blogcatalog.com, linkedin.com, facebook.com etc.



Interestingly, this blog appeared in search engines not just when 'dental materials' were used as keywords. In fact, the visitors of this blog entered more than 400 keywords, such as 'dental materials journal', 'mta dental material', 'filtek silorane', 'mta in endodontics', 'free dental material journal', 'books of dental materials' etc.

So, it's been an exciting period for dental-materials.blospot.com and I hope this blog will be even better in the future. I'd like to thank all the visitors and wish Merry Christmas and a very happy and prosperous New Year.

Light curing of resin-based composites and adhesive systems

Light cured resin-based materials are predominantly used in current dental practice. Light curing protocols have changed over time following changes particularly in light-curing units (LCUs) since the photoinitiator system in these materials has remained virtually unchanged. Though there are attempts to modify the photoinitiator system, the most frequently used one is based on camphorquinone and a tertiary amine.

On the other hand, the LCU technology has been developing in several directions. LCUs comprise four different types of light sources: halogen, light-emitting diode (LED), plasma arc and laser. Halogen and LED LCUs are most often used in dental practice and studied in the dental literature. Light intensity and curing time have been identified as important parameters in monomer conversion which affect mechanical characteristics of the resultant polymer and subsequently its clinical performance. As light intensity has increased from about 500 mW/cm2 which is characteristic of the so-called ‘conventional’ LCUs to more than 700 mW/cm2 in the so-called ‘high-power’ LCUs, most manufacturers recommend shorter curing time. Consensus opinion in the current dental literature is that light energy density (light intensity multiplied by curing time) is a more important determinant of the degree of conversion of resin-based composites (RBCs) and adhesives than light intensity. It is currently recommended to cure adhesive systems for 20 s with LCUs operating at intensities of about 500 mW/cm2 and 10 s with LCUs operating at intensities of more than 700 mW/cm2. For RBCs, the recommended curing time is 40 s with the former LCUs and 20 s with the latter ones. The recommended thickness for each layer of RBCs in the incremental technique is still 2 mm.
Though many LCUs possess additional curing modes, such as soft-start or pulse in order to reduce polymerisation shrinkage of RBCs, there is no scientific evidence that these modes affect the long-term clinical performance of resin-based restorations.

It has been shown that maximum absorption range of camphorquinone is about 468 nm and therefore most LCUs, especially LED and plasma arc, have a very narrow emission range. However, the absorption range of co-initiators may be outside the emission range of such LCUs, thus, leading to insufficient conversion. Most recently, the so-called ‘poly-wave’ LCUs have been introduced on the market in an attempt to cover the absorption range of the entire photoinitiator system and produce maximum conversion for a given material. Future studies will show whether this new approach ensures such monomer to polymer conversion which would lead to better mechanical properties of RBCs and adhesives.

Studies have shown that increased curing distances lead to lower degree of conversion and it has recently been suggested that 6 mm may be a cut-off distance. However, it should be noted that various LCUs and materials may exhibit differences in curing efficiency at various distances. Therefore, as a general rule, the LCU tip should be placed as close as possible to the surface of RBCs and adhesives.

The superficial layer of RBCs and adhesives is insufficiently cured due to oxygen inhibition. It is removed by polishing RBCs but in adhesives, this layer serves as an intermediate zone enabling the formation of the RBC-adhesive bond. It is, therefore, important to use RBCs and adhesives with compatible chemical composition in order to achieve optimal RBC-adhesive bond by interaction of compatible monomers from both materials.

Surface roughness of resin-based composites

The study "Surface characterisation of resin-based composite materials using atomic force microscopy" was successfully presented by Ana Ergic and Dejan Nedeljkovic at the IADR-CED conference in Munich. Click on the image to enlarge the poster. Ana and Dejan are my former students who were involved in this study as part of their student research project. They have recently graduated at the University of Belgrade School of Dentistry.
I'd like to point out that a custom-made device was used in this study to standardise mechanical aging which was performed as a series of brushing cycles using commercial toothbrushes and abrasive toothpaste.

More recent RBCs showed lower surface roughness values before and after aging compared to the control mycrohybrid RBC, Filtek Z250. Surface roughness for N'Durance was found to be similar before and after aging whilst Tetric EvoCeram and Filtek Silorane showed increased roughness after aging.
Keywords: dental materials, resin-based composites, roughness, AFM

The Dental Materials Blog Team expands

Alexander A. Spriggs BSc joins the Dental Materials Blog

It is my pleasure to announce that Alexander A. Spriggs has joined the Dental Materials Blog. Alexander has a BSc Major in Biology and, at the moment, is pursuing second degree in Biochemistry while awaiting Dentistry acceptance at Dalhousie University, Halifax, NS, Canada.

In addition to his academic activities, Alexander owns and operates a construction company, Evolve Construction Services (http://www.evolveconstruction.ca/). It specializes in delivering environmental impact assessments along with construction services to suggest and execute a more environmentally sustainable project. He is conducting research for new solvents frequently used in the construction industry. The objective is to produce a specific solvent from non/low toxic materials that would eventually replace a current solvent on the market with a high toxicity.

Alexander is also doing a case study on Oral Health Care of Remote Populations: Nunavut, Canada, aimed at evaluating how isolated and remote communities suffer from dramatically different oral health standards when compared to more developed regions of the same country. Inclusive to this study was the aboriginal peoples of the remote province of Nunavut, Canada, and their understanding and application of modern medicine.

During 2007 Winter Semester, he presented an Industrial Microbiology Research Project for Dalhousie on the inception of Thymol into a breath mint to determine if the antimicrobial properties would be effective in improving oral health.

During the course of his education, Alexander has become competent in many laboratory techniques, such as:

• Agar plate preparation, inoculation, and experimentation on bacterial / fungal communities
• Bacterial staining / Slide preparation
• Recombinant DNA techniques
• Read and analyze most NMR print outs
• Microscope technique / operation

In addition, he is a skilled web designer, competent in web creation via HTML and PHP code. I’m sure the Dental Materials Blog will soon have a much nicer layout.

For Alexander’s full CV, you may contact him at a.spriggs@gmail.com

BSDR Conference in Glasgow

As previously announced, the BSDR Conference is taking place in Glasgow. The Santini Miletic Research Group presented a study entitled "The ratio of carbon-carbon double bonds in different BisGMA/HEMA mixtures". Click on the image.
Prior to the poster session, I attended the Ceramics session chaired by professor Richard Van Noort. Several very interesting studies were presented regarding CAD-CAM ceramic strength, ceramic reinforcements, fluoride-containing bioactive glasses, leucite glass-ceramic crystallisation, coating materials for zirconia ceramics and wear quantification using profilometry. It was quite impressive to see the very high standard of research carried out at various universities in the UK.

Sponsored by 3M ESPE, the Dental Materials Group Symposium was held during the afternoon session. After the opening remarks by Dr Garry Fleming and Professor R. Van Noort, lectures were given by Dr Rainer Guggenberger (The chemistry of new resin systems), Professor David Watts (The measurement of shrinkage and contraction stress), Professor Tim Watson (The quality of adhesion) and Professor Trevor Burke (Early thoughts of clinical experience using the novel silorane-based composite material). The lectures increased our knowledge on various aspects of resin-based composites and the silorane-based material in particular. The 'non-shrink' resin composites are still not a reality but dental technology has made substantial improvements towards this goal.

Publishing papers: initial observations as an author and a referee

Three basic rules for referees

I've published 9 papers in peer-reviewed dental journals in the last 2 years and have refereed half a dozen papers regarding dental materials, adhesives, resin-based composites, adhesive cements, adhesion, marginal adaptation... Since there's no 'school' or 'course' for referees that I'm aware of, I've started developing my own style. Judging from other people's reviews of my papers, this seems to be the case with most referees out there. I know that the following are very basic rules, but sometimes, even such basic rules are not followed.

Though editors put a lot of effort in finding the right referees for a particular paper, it's possible that a paper ends up in wrong hands, with someone whose field of expertise has almost nothing to do with the subject of the paper. I've noticed very 'interesting' remarks regarding one of my papers indicating that the referee wasn't an expert in the field he/she was referring to. Obviuosly, nowadays a lot of studies are multidisciplinary and this makes it even more difficult for editors to find competent referees. A potential referee may be an expert regarding only a part of a particular study. It's only fair to comment on that part and indicate this to the editor so that a competent person is invited to comment on the other part(s).

So, rule No.1: accept an invitation to review a paper only if you're an expert in the field or at least a part of it and indicate this to the editor. Decline review if the subject of the paper is not your area of expertise.

Another thing I've noticed with people refereeing my papers is that this process sometimes takes ages. Though some journals have taken steps to ensure speedy review within 3-6 weeks, with some journals this may take even more than 6 months. This is simply unacceptable. Being in a referee's position myself, I've realised that even 3 weeks is more than enough to complete a review. Of course, I'm well aware of the fact that referees are very busy and have many, many other things to do. But so are the authors and referees should respect that. It's unfair to keep someone's paper 'under review' for more than a month.

So, rule No.2: accept an invitation to review a paper only if you can complete the review in less than 3 weeks.

Also, I've noticed that there are people who just don't care about the paper they're reviewing. They tend to write and overall impression of the paper without going into specific details. This is not helpful even if the paper is good and especially if it needs to be improved. It's almost like they just skimmed through the paper. On the other hand, there are people who write extensive reviews and I find these extremely helpful.

So, rule No.3: be fully committed to reviewing a paper. Go into minute details when writing a review.

Keywords: dental materials, research, publishing papers, review process.

Santini Miletic Research Group: new website

The new website of the Santini Miletic Research Group is up and running. Please visit us at http://www.santinimiletic.com/

In addition to the short CVs of group members, there is a list of selected papers published recently in international peer-reviewed journals. There is also information on research facilities available to the Group and various methods of knowledge transfer.