Mineral Trioxide Aggregate (MTA) and direct pulp capping

Two papers have been published recently on the use of mineral trioxide aggregate (MTA) for direct pulp capping.

A large clinical trial was conducted between 2001 and 2006 at Ruprecht-Karls-University of Heidelberg, Germany (1). Direct pulp capping with either MTA or Calcium hydroxide was done in 167 teeth of 149 patients. Treatment outcome was evaluated clinically and radiographically by calibrated examiners 12-80 months post-treatment. The authors reported a high recall rate of more than 70% and based the statistical analysis on 108 patients and 122 treated teeth. A significantly greater success rate was found for MTA (78% of teeth) than Calcium hydroxide (60% of teeth). It seems critical to restore such teeth permanently as soon as possible after pulp capping. This study showed that teeth permanently restored ≥2 days after capping had a significantly worse prognosis irrespective of the capping material. The authors concluded that "MTA appears to be more effective than calcium hydroxide for maintaining long-term pulp vitality after direct pulp capping".

Another study is an immunohistological study on Wistar rats (2). It compared the proliferation of pulp cells 1, 3, and 7 days after direct pulp capping with either MTA or Calcium hydroxide. After 3 days, the number of proliferating cells (fibroblasts, endothelial cells and Hoell's cells) was significantly greater when capping was performed irrespective of the material compared to the control group with no capping. After 7 days, however, there were no differences between MTA and Calcium hydroxide groups and the control group. The authors concluded that "Immunohistologic analysis demonstrated that MTA showed similar results when compared with Calcium hydroxide within the first week after direct pulp capping".

(1) Mente J, Geletneky B, Ohle M, Koch MJ, Friedrich Ding PG, Wolff D, Dreyhaupt J, Martin N, Staehle HJ and Pfefferle T. Mineral trioxide aggregate or calcium hydroxide direct pulp capping: an analysis of the clinical treatment outcome. J Endod 2010;36:806-13.

(2) Dammaschke T, Stratmann U, Wolff P, Sagheri D and Schafer E. Direct pulp capping with mineral trioxide aggregate: an immunohistologic comparison with calcium hydroxide in rodents. J Endod 2010;36:814-9.

Reprints of both studies should be available from the authors: (1) johannes.mente@med.uni-heidelberg.de
and (2) tillda@uni-muenster.de

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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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News from Esstech, Inc.

Esstech, Inc. develops and manufactures advanced materials for many biomedical fields including dental materials. In their range of products are various monomers, initiators, silanated glass etc. for resin-based composites and adhesive systems. The latest research by or using Esstech's products includes studies on physical properties of new low shrink resin , optimizing the degee of conversion and certain physical properties of various BisGMA/BisEMA/TEGDMA formulations , optimizing silanated glass , developing a high molecular mass monomer to substitute HEMA etc.

For more information, check out their website and blog.

Esstech, Inc. will be present at the IADR/AADR General Session in Barcelona, Spain (14-17 July 2010) and I really look forward to meeting their representatives, hoping that we could establish scientific collaboration.

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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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Free live dental webinar @ GC Learning

Glass Ionomers: A Therapeutic Alternative to Direct Composite Restorations

Presenter: Dr Daniel Ward, D.D.S.
Time: 23-March-2010. 7:00 pm ET (midnight, 12 am GMT, 24-March-2010)

This webinar is credited with 1 CE credit.
Prior to entering the class, you have to create an account for free.

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News from jobs.ac.uk

Reader in Biomaterials
The University of Manchester - School of Materials

Salary: £46,510 - £60,685 p.a.
Application deadline: 23 - March - 2010
Click here for more information.

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Refractive Index of Methacrylate Monomers & Polymers

It is my pleasure to share this post originally published by Esstech, Inc. www.esstechinc.com
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TECHNICAL BULLETIN:  Refractive Index of Monomers and Their Respective Polymers

The refractive index (RI) of photopolymers is an essential property for many applications.  For optical and coating applications, the RI can be related to the resultant gloss or clarity upon cure.  Within the dental industry, the refractive index of the organic polymer matrix, must match that of the inorganic filler and substrate in order to avoid obvious “lines” where the product is applied.

Various factors affect refractive index values.  The presence of conjugated ring structures contributes to increasing RI.  In general, larger molecular weight monomers have a tendency to possess a higher RI in comparison to their lower molecular weight counterparts.  Similar to this trend, high molecular weight functional groups like methacrylates have higher RI than their acrylate counterparts. Higher atomic weight atoms also seem to be predisposed to having higher RI.

Recognizing the importance of refractive index to our customers, Esstech has assembled RI data for a portion of our existing monomer products as well as their corresponding homopolymers.

Maintaining its position as an industry innovator, Esstech has also created functional, high refractive index materials.  Contact us to learn more about these novel materials and how Esstech can make a material to match your application.

 (P) 800-245-3800 / (P) 610-521-3800 / techsupport@esstechinc.com / www.esstechinc.com

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