Luting agent

Abstract: Statement of problem In contrast to gold crowns, in vitro determination of the retentive strength of all-ceramic crowns is more difficult because components allowing connection to testing apparatus are not as easily integrated into the all-ceramic material. Nevertheless, retentive strength data are crucial for obtaining information about the potential clinical performance of luting cements for all-ceramic restorations. Therefore, a new in vitro model was necessary to evaluate the retentive strength of all-ceramic crowns. Purpose The purpose of this in vitro study was to determine the retentive strength of 4 resin-cement systems, a compomer, a glass-ionomer cement, a resin-modified glass-ionomer cement, and a self-adhesive resin for luting zirconium oxide ceramic crowns. Material and methods One-hundred-twenty extracted human teeth were randomly divided into 12 groups (n=10) and prepared in a standardized manner (5-degree taper, 3-mm occlusogingival height). All-ceramic crowns (Lava) were fabricated in a standardized manner for each tooth. The following cements and corresponding bonding regimens were used to lute the crowns to the teeth according to manufacturers' recommendations: CO, Compolute/EBS Multi; CO/RT, Compolute/EBS Multi/Rocatec; CB, Superbond CB CB/RT, Superbond CB CB/PL, Superbond CB PA, Panavia F; DC, Dyract Cem Plus/Xeno III; CH/PL, Chemiace II/Porcelain Liner M; RL, RelyX Luting, K/C, Ketac Cem/Ketac Conditioner; K, Ketac Cem; and RU, RelyX Unicem. After thermal cycling (5000 cycles, 5°C-55°C), the outer surfaces of the cemented zirconium oxide ceramic crowns were treated (Rocatec) to improve bonding and then placed into a low-shrinkage epoxy resin block (Paladur). The block/crown and tooth components for each specimen were connected to opposing ends of a universal testing machine so that crown retention could be measured. Crowns were removed from teeth along their path of insertion. The retentive surface area (mm 2 ) was determined individually for each tooth. Statistical analyses were performed using the Wilcoxon exact test, ( α =.05) and a Bonferroni correction ( α =.001). Results The median (minimum/maximum) retentive strength values (MPa) were as follows: CO, 1.7 (0.6/4.3); CO/RT, 3.0 (1.3/5.4); CB, 4.8 (3.7/7.9); CB/RT, 8.1 (4.2/12.7); CB/PL, 5.3 (3.7/10.2); PA, 4.0 (3.3/5.1); DC, 3.3 (2.1/5.6); CH/PL, 4.0 (1.3/6.3); RL, 4.7 (2.8/6.6); K/C, 1.8 (0.6/2.3); K, 1.9 (0.2/4.5); and RU, 4.8 (2.5/6.7). Superbond C&B (+ Rocatec) specimens showed the highest median retentive strength, but were not significantly different from Superbond C&B without Rocatec pretreatment of the all-ceramic crown's inner surface. Compolute specimens also did not benefit significantly from the Rocatec pretreatment. Within the materials used without pretreatment of the ceramic, Superbond C&B, Panavia, Dyract Cem Plus, RelyX Luting, and RelyX Unicem showed the highest median retentive strength values and were not significantly different. Conclusion Within the conditions of this study, the compomer-cement, the resin-modified glass-ionomer cement, and the self-adhesive resin luting agent had the same level of retentive quality as the resin luting agents, Superbond C&B, and Panavia. Rocatec pretreatment of the ceramic surface did not improve the retentive strengths of Compolute and Superbond C&B.

Abstract: Aim To investigate the effects of luting agent and thermocycling on bond strengths to root canal dentine. Methodology Extracted maxillary canines (n =144) were root filled and divided into six groups of 24 teeth each. Fibre posts (FRC Postec) were inserted using six luting agents: Panavia F, Multilink, Variolink II, PermaFlo DC, RelyX Unicem and Clearfil Core. Each root was sliced into six discs (thickness 1 mm) representing the coronal, middle and apical part of the root canal. Push-out tests were performed 24 h after post insertion (n = 12) as well as after thermocycling (5000×; 5–55 °C, 30 s) (n = 12). Statistical analysis was conducted using analysis of variance (anova) followed by post-hoc comparisons (Tukey-B). The influence of thermocycling on bond strengths was investigated for each material and region separately using t-tests. Results The bond strengths were significantly affected by the luting agent (P < 0.001), the root position (P = 0.003) and thermocycling (P < 0.001; three-way anova). RelyX had significantly higher bond strengths compared with all other materials (P < 0.05; Tukey-B). The apical region of the root canal had significantly higher bond strengths compared with the middle and coronal region (P < 0.05; Tukey-B). After thermocycling for RelyX a significant increase in bond strengths was detected for the middle and apical region (P < 0.01; t-test, Bonferroni factor 18). Conclusions Bond strengths were affected significantly by luting agent and root position. RelyX had higher bond strengths compared with other materials. The apical region of the canals was characterized by significantly higher bond strengths.

Abstract: Purpose To review the literature on adhesive luting of fiber-reinforced composite posts (FRC) to provide evidence for the clinical procedure of restoring endodontically treated teeth using FRC posts. Methods Data focusing on bonding behavior between root canal dentin, luting agent, and FRC post in vitro as well as in vivo performance of teeth restored with FRC posts were reported. These data were identified by searches of "PubMed", "Scopus", and "Cochrane Library" databases with the terms "post-endodontic restoration", "fiber post", "adhesive luting", "root canal dentin", "clinical study", and "pre-treatment fiber post". Papers published up to September 2007 were selected, and most relevant references were chosen. Cross-referencing of significant papers identified additional relevant articles. Results FRC posts seem to have become increasingly popular for the restoration of endodontically treated teeth. Compared to metal posts, FRC posts revealed reduced fracture resistance in vitro, along with a usually restorable failure mode. Bonding behavior among FRC post, luting agents, and root canal dentin demonstrated varying results. Bond strengths between FRC posts and resin cements can be enhanced by using various pre-treatment procedures; however, bonding to root canal dentin still seems to be challenging. Most clinical studies investigating survival rates of teeth restored with FRC posts revealed promising results, but risk factors (e.g., the loss of coronal tooth structure) have not been studied intensively. In addition, randomized controlled clinical long term trials are scarce.

Abstract: Statement of problem Because of their specific mechanical properties, all-ceramic restorations demonstrate a lower fracture resistance than ceramic restorations supported by metal substructures. However, advances have been made in the fabrication of high-strength all-ceramic abutments for anterior implants. No previous study has compared the fracture loads between 2 different all-ceramic abutments restored by glass-ceramic crowns. Purpose The purpose of this in vitro investigation was to quantify the fracture load of implanted-supported Al 2 O 3 and ZrO 2 abutments restored with glass-ceramic crowns. Material and methods Two ceramic abutments were tested: an Al 2 O 3 abutment (CerAdapt) and a ZrO 2 abutment (Wohlwend Innovative). The abutments (n = 10) were placed on Branemark dental implants and prepared for restoration with glass-ceramic crowns (IPS Empress). After fabrication, in accordance with the manufacturer's guidelines, the crowns were bonded to the all-ceramic abutments with a dual-polymerizing resin luting agent. The fracture loads (N) were determined by force application at an angle of 30 degrees by use of a computer-controlled universal testing device. The data were analyzed with the unpaired t test (α=.05). Results Statistical analysis showed significant differences between both groups ( P =.001) of all-ceramic abutments, with mean fracture load values of 280.1 N (± 103.1) for the Al 2 O 3 abutments and 737.6 N (± 245.0) for the ZrO 2 abutments. Conclusion Within the limitations of this study, both all-ceramic abutments exceeded the established values for maximum incisal forces reported in the literature (90 to 370 N). The ZrO 2 abutments were more than twice as resistant to fracture as the Al 2 O 3 -abutments.