Dr. med. dent. Ludwig Hermeler, Rheine, Germany
Temporary restorations play an important role in the fabrication of fixed prostheses. Whilst for dentists the focus is firmly on protecting the prepared teeth and ensuring good fracture-resistant strength, patients increasingly expect temporary restorations to satisfy aesthetic demands and to also have a surface quality that is pleasant to the touch. VOCO has now developed an enhanced self-curing composite for the fabrication of crowns and bridges. Based on VOCO’s own nano-hybrid technology, Structur 3 sets a new standard in three important are as: handling, aesthetics and durability.
The 1:1 cartridge system, containing either a 50 ml cartridge or a 5 ml QuickMix syringe, guarantees homogeneous mixing and uniform curing. It is thus the ideal choice for ensuring error-free and simple application, just like Structur 2 and Structur Premium. The patient-friendly intraoral curing time of 45 seconds is considerably shorter than with comparable competitor products. Heat generation during polymerisation is a key handling parameter. Materials which generate a temperature of 41°C during curing pose the risk of devitalisation due to denaturing. The measurements conducted by Dr. Borchers in his study “Temperature rises in the pulp of prepared teeth when curing temporary restorations made from various composites” at Hanover Medical School (MHH) show that pulpal overheating is not possible with Structur 3 . Compared to the other materials, Structur 3 produces the smallest rise in pulp temperature during intraoral curing. Finishing of the edges can begin just four minutes after the start of mixing, and the only prior step required is to wipe away the inhibition layer, formed by oxygen, using a cloth soaked in alcohol in order to achieve a lustrous shine. The study by Fleming concluded that, amongst other things, Structur 3 has the least surface roughness after removal of the inhibition layer compared to the main competitor materials on the market . Timeconsuming polishing of the Structur 3 surface is not required; so finishing time is reduced even further.
The smoother surface, as demonstrated in the above study, means that patients can remove plaque more easily, so the temporary restoration resists discoloration and remains aesthetically pleasing for longer. The fluorescence of Structur 3 has been adapted to that of human teeth, which further contributes to the optimal appearance of the temporary restoration. A selection of 8 shades enables precise adjustment to the patient’s natural tooth shade.
Fractures in temporary restorations are unpleasant for patients, while for the dental practice, the repair or refabrication of temporary restorations costs time and money. The physical parameters of the materials used for temporary crowns and bridges, including long-term temporaries, must enable them to reliably withstand daily masticatory loads over an extended period of time. In a study at the University of Regensburg , temporary crowns were produced from a variety of materials and their fracture resistance was tested. The study demonstrated that Structur 3 has the highest degree of fracture resistance. With a compressive strength in excess of 500 MPa (based on ISO 9917), efficient fracture resistance is assured.
Anterior trauma suffered by a 57-year-old patient caused the ceramic veneer of her bridge to fracture extensively in several places in the region 13 to 23 (upper canine to upper canine). It was initially restored directly with a composite after the accident. Prior to fabrication of the new restoration, an alginate impression is taken, which serves as the negative mould for the Structur 3 restoration after removal of the bridge and post-preparation. In the past, when making temporary restorations from less resilient materials, our dental practice used to take silicone impressions for the fabrication of the temporary crowns and bridges. These impressions were kept for later use in repair or refabrication in the all-too-frequent event of damage. Since switching to Structur 3, this is no longer necessary, based on our good experience with this material. The alginate impression filled with Structur 3 is reinserted. After 45 seconds of intraoral curing, the material is still slightly elastic and can be easily removed from the stumps. 4 minutes after the start of mixing, the temporary restoration has cured sufficiently to be finished. The inhibition layer is wiped away with a cloth soaked in alcohol, and a lustrous shine is already visible. The bulk of the excess material can be removed with crown scissors and rotary instruments. Interdental finishing is important for ensuring that the temporary restoration can be kept hygienic. After rough finishing, the fit is checked intraorally. The result after polishing the nanohybrid surface, preceded by finishing with rotary instruments, is indeed both highly aesthetic and functional and, at the same time, the finishing time has also been noticeably reduced. The smooth Structur 3 surface is particularly pleasant to the touch for the patient, who can now smile and eat without any worries with this temporary bridge.
Thanks to nano-hybrid technology, Structur 3 from VOCO puts in a “shining” performance in the criteria of handling, aesthetics and durability of self-curing composites. The dentist is able to produce high-quality and aesthetic restorations which feel good in the patient’s mouth and are also extremely durable – as well as taking less time. Reason for both patient and dentist to smile.
1. Fleming et al., Trinity College Dublin, 2012
2. Dr.-Ing. Lothar Borchers, Hanover Medical School (MHH), report on the commissioned study „Temperaturerhöhung in der Pulpa präparierter Zähne bei der Aushärtung von Provisorien aus verschiedenen Kunststoffen“ (Temperature rises in the pulp of prepared teeth when curing temporary restorations made from various composites), 26.07.11
3. Dr. Reinhard Lang, University of Regensburg