Dental Conference: It's all about the Margin - 2013 Espertise™ Experts Roundtable
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Dental Conference: It's all about the Margin - 2013 Espertise™ Experts Roundtable
Nov 19-20, 2012 Starnberg, Germany
Discover research papers, videos & information of 3M ESPE's Espertise™ Dental Experts Conference (2013) on success factors of quality restoration margins.
The margin of a restoration is the most vulnerable part of it: inaccuracies in this area may lead to inflammation of the soft tissue. In addition, an imprecise fit or insufficient bond strength at the interface between the tooth and the restoration often results in microleakage and ultimately in failure of it – no matter whether it is a composite filling, a single crown or a multi-unit bridge.
Outcome: All speakers and participants agreed that improving the quality of the restoration margin is an important goal. Proper tissue management and the use of high-quality materials and devices during preparation, impression taking, cementation and all work steps in the laboratory is decisive for precise restorations with good marginal fit. The standardization of workflows – e.g. through the use of digital technologies – may lead to more and consistently more accurate results in the restoration process.
The margin of a restoration is the most vulnerable part of it: inaccuracies in this area may lead to inflammation of the soft tissue. In addition, an imprecise fit or insufficient bond strength at the interface between the tooth and the restoration often results in microleakage and ultimately in failure of it – no matter whether it is a composite filling, a single crown or a multi-unit bridge. In order to address this highly relevant topic in an exclusive group of dental professionals, 3M ESPE organized an Espertise™ Dental Experts Conferences entitled “It’s all about the margin” which took place at November 19 and 20, 2012 in Starnberg, Germany.
After the opening of the event by Prof. Dr. Ivo Krejci (University of Geneva, Switzerland), Dr. Al Viehbeck, Vice President, Research & Development Materials at 3M ESPE, presented the challenges for R & D in developing products that lead to the perfect margin. For him, a high level of innovation and quality management that touches every department and every 3M ESPE employee are key to success.
Afterwards, Prof. Dr. Bernd Wöstmann (University of Gießen, Germany) focused on the preparation and the restoration margin and highlighted the fact that inaccuracies at the margin of a restoration may cause tissue inflammation. According to him, maximum accuracy of a restoration can be achieved by a standardization of every single work step in practice and laboratory – including the selection of the impression material and technique as well as the room temperature during model production. The use of digital technologies can be advantageous in the striving for a standardized workflow. In his conclusion, the lecturer called for a well-structured management of the patient, the tissues and the biomaterials used to advance clinical reality.
Prof. Dr. Albert Feilzer (Academic Center for Dentistry Amsterdam, the Netherlands) tried to answer the question if digital dentistry might be the path towards optimal marginal quality. He pointed out that digital technologies such as optical impression taking eliminate some of the traditional problems that may lead to inaccuracies. At the same time, however, he showed that there are many separate digital technologies which have to be integrated into one system in order to tap the full potential. What is still missing is a standardized data format, infrastructure for data transfer and high performance database software at universities. In order to reach this goal, cooperation of different companies and institutions is necessary.
In five poster presentations, the young researchers Dr. Marco Gesnigt (Groningen, the Netherlands), Dr. Beatriz Giménez Gonzales (Madrid, Spain), Dr. Jan-Frederik Güth (Munich, Germany), Dr. Anne-Kathrin Lührs (Hannover, Germany), Dr. Anke Wald (Gießen, Germany) summarized their research results and focused on different topics: Dr. Gesnigt found that marginal defects leading to failure of ceramic veneers that were placed over existing composite restorations may be prevented by surface conditioning of the composite. Dr. Giménez Gonzales and Dr. Güth focused on accuracy and predictability of dental intraoral scanners, like the 3M™ ESPE™ Lava™ Chairside Oral Scanner C.O.S . They agreed that, while the accuracy of the devices is often better than that of conventional impressions, there are still some thresholds in the digital process that have to be overcome. Dr. Lührs presented the results of a study that investigated the polymerization of bonding systems and its effect on marginal quality, showing that light-curing of resin cements is superior to dark curing with many products. A clinical study on the effect of different soft tissue management systems – including the new 3M™ ESPE™ Astringent Retraction Paste – on sulcus exudate flow was initiated by Dr. Wald. Her conclusion: plain cotton cords did not perform well, but a successful drying of the sulcus was achieved with the tested retraction pastes.
Retraction paste …
3M ESPE Astringent Gingival Retraction Paste took centre stage at the second day of the event: Dr. Andreas Maurer, developer of the innovative product at 3M ESPE, gave insights into the evolution of the development project. In 2008, the team identified the need for a paste that offers mechanical retraction and controls exudation during impression taking and exudation. An additional device for the dental practice should not be required and suitability for digital and conventional impression taking was an important goal. Also, the aim was to make it better, faster and easier than existing pastes. What was particularly challenging during the project was the development of a consistency that was stiff, but easily extrudable from a very fine tip using an existing dispenser. Recent market feedback confirms that the goals were met and the interest in the new product is high.
… in clinical use
The use of the paste in general dental practice was illustrated by Dr. Rafal Medzin (Dentura Clinic, Gryfino, Poland), who showed numerous clinical cases and recommended an equigingival preparation whenever possible to protect the soft tissue. He utilizes the gingival retraction paste in several indications, especially in combination with one cord instead of adopting the double cord technique. The cord is placed first and the retraction paste is applied on top of it, the procedure being faster and more comfortable than the use of two cords. Stating that there is always the other side of a margin, Dr. Paulo Monteiro (Santiago de Compostela, Spain) also presented several clinical cases where he used the astringent retraction paste alone or in combination with a thin cord. The results of an evaluation of the novel product in general dental practice were summarized by Prof. Dr. Trevor Burke (University of Birmingham, UK). Twelve evaluators of the PREP Panel tested the astringent retraction paste in their dental practice for ten weeks for a total of 160 impressions and 25 restorations. The rating was very good, with 83% of the evaluators agreeing that the use of the paste makes the retraction procedure more efficient. The overall rating for ease of use was higher for the new system than for the previously used retraction method and a great majority of the evaluators (83%) would recommend the product to their colleagues.
… and from a scientific viewpoint
Prof. Dr. Ralph G. Luthardt (University of Ulm, Germany) presented the results of a study that examined the amount of tissue displacement with retraction cords and with a kaolin-aluminium chloride paste in healthy tissues and tissues with a mild gingivitis. He found that gingivitis does not influence the displacement capacity of the paste while the displacement capacity of the cords was significantly decreased. Permanent gingival recession was not observed. Prof. Dr. Karl-Heinz Kunzelmann (University of Munich) uses 3M ESPE Astringent Retraction Paste on a routine basis and initiated a study to test in vitro by shear bond testing if the material has an impact on dentin bonding. Indeed, all tested hemostatic products caused a decrease of the shear bond strength. Further investigations are necessary to identify the reason for this reaction as well as solutions.
All-ceramics and the margin
Marginal integrity of all-ceramic restorations was the main topic of the lecture of Prof. Dr. Daniel Edelhoff (University of Munich). While all-ceramic materials are the gold standard for aesthetic restorations due to natural light transmission, the dentist has to adhere to strict preparation guidelines in order to ensure long-lasting success. The lecturer recommends a chamfer preparation and the use of finishing burs at the margin. By elevating the margin, the soft tissue can be protected and less tooth structure is removed, an approach that is always desirable. With regard to impression taking, he identified a great potential of the digital technique. The marginal fit should always be passive with ceramics to avoid fracture and adhesive cementation is preferred over the conventional technique in most cases.
Every restoration is temporary
Prof. Dr. Ivo Krejci agreed with Prof. Edelhoff in that tooth structure should be preserved whenever possible – however, he adopted a very different, conservative approach. Due to the demographic change, every restoration is temporary, so that in the opinion of the speaker, there is no reason against the placement of composite restorations. Often, they work for a long time and do not require destruction of natural teeth. Even in severe cases, Prof. Krejci makes a defect-oriented preparation and seals the cavity with direct restorative material. Afterwards, an indirect composite restoration is placed on top of it – to prevent tooth fracture, a thin layer of glass-fibre reinforced composite is applied as a basis. Subgingival preparation margins should be avoided, but when this is impossible the gingiva is retracted by the speaker with rubber dam and a metal matrix.
Numerous clinical cases which were close to the edge were presented by MDT Andreas Nolte. His cases showed non-invasive procedures as well as implant-borne restorations, many of them made of Lava™ Zirconia. For zirconia abutments, he recommended to always use a fluorescent effect shade which has a great effect on the appearance of the restoration –especially at the margin.
Prof. Dr. Albert Feilzer
tried to answer the question of whether digital dentistry might be the path towards optimal marginal quality.
Dr. Anke Wald
shared her findings on the Clinical effectiveness on different retraction techniques on the crevicular fluid flow in vivo.
Dr. Anne-Katrin Leuhrs
shared her findings on: Do ceramic pretreatment and polymerisation influence the dentine bondstrength of Lava Ultimate.
Dr. Beatrize Geminez
talks about how to achieve predictibility and accuracy with intra oral scanners.
Prof. dr. Bernd Wöstmann
talks about the theoretical quality versus the clinical reality at the margin levels of different restorations.
Prof. dr. Daniel Edelhoff
talks about the marginal fit of all ceramic restorations.
Dr. Gerhard Kultermann
expresses his expectations about how science and industry meet during this event.
Dr. Jan Frederik Guth
shared his findings on how to transfer the high accurate scanning data with intra oral scanners into the real geometry into restorations.
Dr. Marco Gresnigt
shared his opinion on how to handle existing restorations underneath indirect restorations.
Dr. Paulo Monteiro
talks about the other side of the margin.
Dr. Rafael Medzin
talks about the haemostasis and tissue management from a practical perspective.
- Espertise™ Experts Roundtable (pdf, 708,5 kB)
- Albert J. Feilzer: How digital technologies may contribute to marginal quality (pdf, 747,6 kB)
- Rafał Medzin: The impact of soft tissue management on marginal quality of restorations (pdf, 797,5 kB)
- Bernd Wöstmann: Improved marginal accuracy through standardization (pdf, 574,6 kB)
- Paulo Monteiro: A conservative approach to indirect restorations (pdf, 835,6 kB)