Wagner Dental CEREC Blog

 

Summerlin Cerec Dentist 

 

Temporaries weaken the enamel margins

 

When examining the clinical performance of CEREC it is important to discuss the influence of enamel integrity and marginal quality, as well as the effect of temporaries on cavity treatment. In an experiment involving a chewing simulator Roland Frankenberger, Marburg University established that the placement of temporary restorations has a significant negative impact on the integrity of the tooth enamel. Cracking occurred especially in the oral and vestibular surfaces and marginal chipping was also observed. Such enamel defects did not occur in cavities which had been treated immediately using chairside-fabricated CEREC ceramic inlays. Frankenberger concluded that the elimination of the temporary restoration reduces the risk of enamel cracking and marginal chipping. The CEREC inlay creates a force-locked bond with the hard tooth tissue and reinforces the cavity walls. By contrast, the non adhesively luted temporary inlay lies like a wedge in the cavity and transmits the chewing forces directly to the weakened residual tooth. Under the influence of chewing forces the tooth is subjected to torsional stress due to the low elastic modulus of the temporary composite material. This results in an uneven stress distribution, with stress peaks at the interface between the tooth and the temporary. The transmitted force also deforms the inadequately protected cusp walls. In addition, the contamination of the hard tooth tissue with temporary cement compromises the subsequent bond between the enamel/dentine contact surfaces and the silanized ceramic material. An examination of luting systems revealed that conventional multi-bottle systems are still superior to self-adhesive systems. The selective etching of the enamel enhances the bond with the hard tooth tissue, as well as the quality of the margins. Wider adhesive gaps are not detrimental to margin quality. Total length of enamel cracks according to TML Measurements of enamel margin defects with and without the deployment of temporary restorations. Cavities treated with chairside ceramic restorations shown at the bottom of the graph displayed the least occurrence of enamel cracks. CEREC conforms to the gold standard. More than 250 clinical investigations of CEREC restorations have been carried out. In particular, the long-term studies by Bernd Reiss, Winfried Walther, Tobias Otto, Sabatino de Nisco and David Schneider fulfil the requirements of evidence-based study design. Treatment was carried out under the conditions of a private dental practice. Reiss and Walter monitored 1,010 CEREC inlays and onlays, some of which had been fabricated using the CEREC I system. After a service time of 15 – 18 years 84.4 percent were clinically perfect. If the patients are separated into two groups i.e. patients treated with and without the use of a dental adhesive, a significant difference is revealed. Without dental adhesive the survival rate fell to approx. 80 percent after 16 years; with dental adhesive the survival rate was 90 percent... Beginning in 1989, these dentists monitored a total of 200 inlays and onlays and evaluated them on the basis of modified USPHS criteria after a period of 17 years. 187 of the restorations were still in place. Of these, 95 were still intact after allowing for technical criteria. Failures with Charlie and Delta ratings (USPHS) occurred between the 6th and 13th year. In most cases these failures were attributable to ceramic fractures. Overall a survival rate of 88.7 percent was achieved, while the annual failure rate was 0.75 percent. The success rate was thus significantly higher than that of layered lab-produced ceramic inlays and was approximately equivalent to that of alternative long-term restorations – e.g. cast-gold inlays, which have a survival rate of 87 percent after 20 years and an annual failure rate of 0.7 percent. (Otto, T., Schneider, D.: Long-term clinical results of chairside CEREC CAD/CAM inlays and onlays. A case series. Int J Prosthodontics, 2008; 21: 53-59). Gerwin Arnetzl (Graz University) reported positive findings after 15 years. Between 1988 and 1990 he placed 358 two and three-surface inlays made of Dicor, Optec, Hi-Ceram, Duceram and CEREC 1 (Mark I) using the adhesive bonding technique. The control group consisted of cemented gold inlays. After 15 years CEREC and gold had a survival rate of 93 percent. This was significantly higher than the equivalent figure for lab-produced sintered ceramic inlays, which had a failure rate of 32 percent.(Arnetzl, G.: Different ceramic technologies in a clinical long-term comparison. 20-year CEREC anniversary, Berlin, 2006. - Arnetzl, G.: Different ceramic technologies in a clinical long-term comparison. In: Mörmann, W., (ed). State of the art of CAD/CAM restorations. London: Quintessence, 2006: 65-72). Anja Posselt and Thomas Kerschbaum (Cologne University) analyzed the performance of 2,328 CEREC restorations placed in 794 patients in a dental practice. The survival rate after nine years was 95.5 percent. The filling size, tooth vitality, the prior treatment of caries profunda (CP), the type of tooth and the location of the filling – separated according to the upper and lower jaw – did not have any significant influence on the expected success rate... The CEREC restorations perform better in terms of cost-effectiveness compared with durability. Cast gold inlays occupy second place due to their higher production costs... read more

 

Las Vegas Cerec Dentist

 

                                                     Digital Impressions VS Goop Impressions