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Objectives: Aim of the present study was to evaluate fracture strength of endodontically treated molars with different preparations/restorations after thermomechanical loading in vitro., Methods: 264 extracted human third molars were used. Beside the control group, 256 teeth in 32 test groups (n=8) received root canal treatment (MTwo #40/.6) and root canal obturation with AH Plus and Guttapercha. After postendodontic sealing and build-up (Syntac, SDR), specimens were additionally prepared MO or MOD. Postendodontic restorations were: Direct restorations (Tetric EvoCeram Bulk Fill bonded with Syntac; as filling or direct partial crown (PC) after reducing the cusps 3mm; amalgam as filling or direct pin-retained partial crown (PC)), vs. indirect adhesive restorations (I: Inlay vs. PC; IPS Empress I/PC; Celtra Duo I/PC; e.max CAD I/PC; Lava Ultimate I/PC; Enamic I/PC - all inserted with Syntac/Variolink) vs. cemented cast gold I/PC. After 300,000 thermocycles (5/55°C) and 1.2 Mio. 100N load cycles, specimens were loaded until fracture., Results: Whereas IPS Empress showed no difference between I and PC (p>0.05), in all other groups PC were significantly more stable than fillings/inlays (p<0.05), this effect was more pronounced after MOD preparations. Cast gold PC exhibited the highest fracture strengths (p<0.05), inlays the lowest (p<0.05). IPS Empress was generally inferior to the other bonded materials under investigation (p<0.05) which as PC almost reached the level of control specimens. Amalgam fillings showed the worst outcome (p<0.05)., Significances: Less invasive preparation designs were not beneficial for the stability of postendodontic restorations. Except for IPS Empress, PC were generally more successful in restabilization of weakened cusps after endodontic treatment and preparation. Cast gold PC remain the ultimate stabilization tool for ETT in terms of fracture resistance., (Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.)

Objectives: To assess the influence of different temporary restorations and luting techniques of labside and chairside ceramic inlays on enamel defects and marginal integrity., Methods: 120 extracted human third molars received MOD preparations with one proximal box each limited in either enamel or dentin. 64 Cerec 2 inlays and 56 IPS Empress I inlays were randomly assigned to the following groups (fabrication mode: chairside (CS)=no temporary restoration (TR), labside (LS)=TR with Luxatemp (L) inserted with TempBond NE, or Systemp.inlay (SI) without temporary cement), luting technique: SV=Syntac/Variolink II, RX=RelyX Unicem: A: Cerec inlays were luted with (1) CS/SV. (2) CS/SV/Heliobond separately light-cured. (3) CS/RX. (4) LS/L/SV. (5) LS/L/RX. (6) LS/SI/SV. (7) LS/SI/RX. (8) LS/SI/RX with selective enamel etching. B: Empress. (9) L/SV. (10) L/SV/Heliobond separately light-cured. (11) L/RX. (12) SI/SV. (13) SI/SV, Heliobond separately lightcured. (14) SI/RX. (15) SI/RX after selective enamel etching. Before and after thermomechanical loading (TML: loading time of TR 1000×50N+25 thermocycles (TC) between +5°C and +55°C; clinical simulation: 100,000×50N+2500 TC) luting gaps, enamel cracks, and marginal adaptation to enamel and dentin were determined under an SEM microscope (200×) using replicas., Results: Loading time of temporary restorations negatively affected enamel integrity and enamel chipping (p<0.05). Luxatemp resulted in less enamel cracks than Systemp.inlay (p<0.05). Syntac/Variolink achieved better marginal enamel quality than RelyX Unicem in all groups (p<0.05). Marginal quality in dentin revealed no differences when no temporary cement was used (p>0.05). Temporary cement negatively affected dentin margins when RelyX Unicem was used (p<0.05)., Significance: Chairside-fabricated Cerec inlays reduce the risk of enamel cracks and marginal enamel chipping due to omitted temporary restorations. Syntac/Variolink revealed a significantly better performance than RelyX Unicem., (Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.)

Objectives: The aim of the present study was to evaluate the ormocer Definite (Degudent, Hanau, Germany) as resin luting cement., Methods: In a controlled prospective clinical study, 57 Cergogold (Degudent) all-ceramic inlays were placed in 24 patients by four dentists. The restorations were luted with two different systems (MD=Definite Multibond+Definite; SV=Syntac+Variolink Ultra, Ivoclar Vivadent, Liechtenstein) without lining. At baseline, after 12, 24, and 48 months, restorations were examined according to modified USPHS scores and criteria., Results: One patient including three restorations missed the 4 years recall (dropout). After 48 months of clinical service, four restorations in four patients (three luted with Definite, one with Variolink) failed due to inlay fracture (n=3) and tooth fracture (n=1), all other fillings were clinically acceptable (survival rate 93.3% for Definite vs. 95.2% for Variolink; Kaplan-Meier algorithm). Except for the rate of hypersensitivity at baseline (MD: 27%; SV 0%; p<0.05), no differences were evident between the luting cements at any recalls (Mann-Whitney U-test; p>0.05). Between the four recalls, a statistically significant deterioration was detected for both groups regarding the criteria marginal adaptation, filling integrity (cracks/chippings/fractures), and tooth integrity (Friedman test; p<0.001). After 4 years, mainly distinct deterioration with marginal fractures or chippings in proximal and marginal areas of the inlays were observed. No differences were found for surface roughness, color matching, and proximal contact (p>0.05)., Conclusions: For luting of ceramic inlays, only slight differences between the two luting systems were detectable.

Objective: The aim of the present study was to clinically evaluate the suitability of Definite Multibond and Definite ormocer resin composite for luting of Cergogold glass ceramic inlays in a two-center trial involving two dentists., Methods: Thirty-nine patients received 98 Cergogold inlays with at least one inlay luted with Definite Multibond/Definite (n=45) and at least one inlay luted with Syntac/Variolink Ultra (n=53) in a split mouth design. Treatments were carried out in two private practices by two operators (Operator A: n=38; Operator B: n=60). Forty-four cavities required caries profunda treatment, 23 cavities exhibited no enamel at the cervical margin. At baseline (2 months), and after 6, 14, 27, and 51 months of clinical service, the restorations were investigated according to modified USPHS criteria., Results: The drop-out rate was 3% after 4 years. After 48 months of clinical service, 21 restorations in 16 patients (9 luted with Definite, 12 with Variolink; 2 placed by operator A and 19 by operator B) had to be replaced due to inlay fracture (n=11), tooth fracture (n=4), hypersensitivities (n=3), or marginal gap formation (n=3). Seventy-seven inlays were in good condition (survival rate 89.9%, median survival time 4.2 years (95% confidence interval +/-0.25; survival analysis by Kaplan-Meier algorithm). Survival rate after 4 years was 97.4% for operator A, and 75.4% for operator B (p=0.002; Log Rank/Mantel-Cox) resulting in annual failure rates of 0.6% and 6.2%, respectively. The operators did not differently judge the clinical behaviour of the luting procedures (Mann-Whitney U-test, p>0.05). Independent of the operator and the used luting system, the following criteria significantly changed over time: color match, marginal integrity, tooth integrity, inlay integrity, sensitivity, hypersensitivity, and X-ray control (p<0.05; Friedman test). Significant differences between operators over the whole period were computed for the criteria marginal integrity, tooth integrity, and inlay integrity (p<0.05, Mann-Whitney test). Differences between luting materials were only present during single recalls., Significances: For luting of ceramic inlays, only slight differences between the two luting systems were detectable. The operator influence on clinical outcome was clearly proven.

Purpose: To prospectively compare the clinical performance of two different resin composites for luting IPS Empress inlays and onlays., Methods: 83 IPS Empress restorations were placed in 30 subjects. All restorations were inserted under rubber dam. 43 inlays/onlays were luted with a self-adhesive resin cement [RelyX Unicem (RX)]. A multistep adhesive (Syntac) was used with Variolink II low viscosity (SV) and served as control (n=40). The restorations were evaluated after 2 weeks: Baseline = 1st recall (R1), after 6 months (R2) and after 1 year (R3) by two calibrated examiners using the modified USPHS criteria., Results: From R1 to R3, one failure was noticed in the SV group (R2) due to marginal enamel chipping. After 1 year of clinical service, SV revealed significantly better results regarding color match and integrity inlay (Mann-Whitney U-test, P< 0.05). No statistically significant differences were observed between SV and RX for the remaining criteria (Mann-Whitney U-test, P>0.05).

Purpose: This controlled clinical trial aimed to evaluate IPS Empress inlays and onlays over 12 years. The null hypothesis was that different luting resins would have no influence on clinical outcome., Materials and Methods: In the course of a prospective clinical long-term trial, 96 ceramic inlays and onlays were placed in 34 patients using one adhesive (Syntac) and four different luting composites (Tetric, Variolink Low, Variolink Ultra, Dual Cement). Recalls were carried out by two calibrated investigators using modified USPHS codes and criteria at baseline, 1, 2, 4, 6, 8, and 12 years., Results: Fifteen of the 96 restorations had to be replaced (failure rate 16%; Kaplan-Meier); 12 of them suffered bulk fractures. After twelve years of clinical service, significantly more bulk fractures were found when light-curing composite was used for luting (p < 0.05). Fractures were noticed between 3 and 4 years of clinical service and later after 11 to 12 years; aside from those times, no single fracture occurred. Secondary caries was not observed., Conclusion: IPS Empress inlays and onlays exhibited satisfactory clinical outcomes over a 12-year clinical period. Restorations luted with dual-cured resin composites revealed significantly fewer bulk fractures.

Purpose: The aim of the present study was to clinically evaluate the effect of two different adhesive/resin composite combinations for luting IPS Empress inlays with a special focus on luting gap wear and marginal adaptation., Materials and Methods: In the course of a controlled prospective clinical split-mouth study, 94 IPS Empress restorations were placed in 31 patients. The inlays were luted with EBS Multi + Compolute (EC; 3M ESPE) or with Syntac + Variolink II low (SV; Ivoclar Vivadent). At baseline and after 0.5, 1, 2, 4, and 8 years, the ceramic restorations were examined according to modified USPHS codes and criteria. Thirty-five selected samples were investigated under an SEM regarding morphological changes; marginal quality analysis was carried out using a stereo light microscope, and luting composite wear was scanned with a profilometer., Results: Eight patients (including 25 restorations) missed the recalls; the recall rate at the last investigation was 72%. After 96 months of clinical service, seven restorations in five patients (six EC, one SV) had to be replaced due to hypersensitivities (n = 5) or inlay fractures (n = 2) resulting in a survival rate of 90%. Over the 8-year period, the restorations revealed no statistically significant differences in terms of surface roughness, color matching, proximal contact, sensitivity, or complaints (p > 0.05, Friedman test). Significant deteriorations were found for marginal integrity (p < 0.05). No significant differences were observed for the different luting systems (p = 0.096, Log rank test/ Mantel Cox). Marginal analysis revealed no statistical difference among the materials (p > 0.05; Mann-Whitney U-test), however, the scans of the luting gap showed that Compolute was more prone to wear (p < 0.05)., Conclusion: For luting of ceramic inlays, no difference between the two luting systems was detectable. The overall failure rate after 8 years was 10%.

Objectives: To measure subcritical crack growth parameters in vitro and to correlate those with clinical observations from the 12 years recall of a prospective clinical study., Methods: Bending bars were manufactured and the inert fracture strength was determined in four-point bending and silicon oil. Weibull statistics were applied and the parameters m and sigma(0) were calculated. Dynamic fatigue experiments were performed in water at four decreasing loading rates from 1.3 to 0.0013MPa/s. The parameters of subcritical crack growth n and A were calculated. Strength-fracture probability-life time (SPT) predictions were derived for 1, 4, 8 and 12 years, based on a static crack growth mechanism. The 12 years clinical recall of a prospective clinical study on the same material was performed. Bulk, chipping and marginal fractures or detoriations were focused here. Failure rates were calculated according to Kaplan-Meier survival analysis and merged into the SPT diagram., Results: Inert fracture strength of the glassceramic was measured to sigma(0)=134MPa and the Weibull modulus to m=8.1. The subcritical crack growth parameter n was calculated to n=19.2 and the extrapolated crack velocity to A=0.0014m/s. Based on a clinical relevant failure probability of P(F)=5%, material strength was predicted to decrease from initial sigma(0.05)=93MPa down to sigma(0.05)=33MPa after 12 years (-64%). The clinical survival rate dropped from 100% (1 year) to 93% (4 years), 92% (8 years) and 86% after 12 years. The incidence of inlay defects like chipping and marginal fractures increased from 1% at baseline, 7% after 4 years, 26% after 8 years to 57% after 12 years., Significance: Clinical data match the slow crack growth measurements in terms of dramatically increased clinical bulk fractures and detoriations from marginal and chipping fractures after 12 years. Clinical survival rate seems to converge towards the in vitro lifetime predictions with increasing time. A failure level of P(F)=5% is clinically exceeded after 4 years of clinical service, which corresponds to an experimental prediction of fracture releasing static loading of 35.5MPa. Since average chewing pressure over time is less deleterious compared to static loading, this regression analysis provides a conservative threshold value.

Wear phenomena of ceramic inlays are not fully understood. The aim of the present study was to evaluate ceramic wear, antagonist enamel wear, and luting cement wear over 8 years. The two-fold null hypothesis was that there would be (1) no difference in wear behavior between ceramic and enamel, and (2) no influence of filler content of luting composites on composite wear. From 96 restorations, 36 Class II inlays from 16 participants were selected. For inlays with opposing enamel cusps (n=17), replicas of inlays and enamel were scanned with a 3-D laser scanner. Luting gaps of inlays (n=36) were analyzed with a profilometer, including 3-D data analysis. Ceramic and enamel wear increased between 4 and 8 years, with significantly higher values for enamel after 6 years (p<0.05). Luting gap wear increased continuously up to 8 years (p<0.05), with no influence of luting composites (p>0.05) and location of teeth (p>0.05).

Objective: The aim of the present study was to clinically evaluate the effect of two different adhesive/resin composite combinations for luting of IPS Empress inlays., Methods: Ninety-four IPS Empress restorations were placed in 31 patients in a controlled prospective clinical split-mouth study. The restorations were luted with EBS Multi/Compolute (3M Espe) or with Syntac/Variolink II low (Ivoclar Vivadent) without lining. At baseline and after 0.5, 1, 2, and 4 years, the ceramic restorations were examined according to modified USPHS codes and criteria., Results: Two patients including four restorations missed the 4 years recall (drop out). After 4 years of clinical service, four restorations in two patients (three luted with Compolute, one with Variolink II) had to be replaced due to hypersensitivities, 90 inlays and onlays were acceptable (failure rate 4%; Kaplan-Meier survival analysis). Between the five recalls, a statistically significant deterioration was found for the criteria marginal adaptation and inlay fracture (Friedman 2-way ANOVA; p < 0.05). Between the adhesives no statistical difference was found. At baseline, 95% of the restorations revealed luting composite overhangs. After 4 years, 55% of cases had overhangs and 38% showed marginal ditching. No differences were found for surface roughness, color matching, integrity tooth, proximal contact, hypersensitivity, and satisfaction (p > 0.05)., Conclusion: For luting of ceramic inlays, no difference between the two luting systems was detectable. The overall failure rate after 4 years was 4%.

Objective: Ceramic inlays and onlays are a tooth colored alternative to metallic restorations. Clinical long-term data are scarce though, especially about inlays and onlays having proximal margins in dentin. The present prospective controlled clinical study evaluated the clinical performance of IPS Empress inlays and onlays with cuspal replacements and proximal margins below the cementoenamel junction over eight years., Methods: Ninety six ceramic restorations were placed in 34 patients by six dentists. The restorations were bonded with an enamel/dentin bonding system (Syntac Classic) and four different resin composite systems. The restorations were assessed after placement by two calibrated investigators using modified USPHS codes and criteria at the following time periods: baseline, 1,2,4,6 and 8 years., Results: Eight of the 96 restorations investigated had to be replaced (failure rate 8%; Kaplan-Meier): Six inlays suffered cohesive bulk fractures, two teeth required endodontic treatment. After eight years of clinical service, significant deterioration (Friedman 2-way ANOVA; P < 0.05) was found for marginal adaptation of the remaining restorations. 98% of the surviving restorations exhibited marginal deficiencies, independent of the luting composite., Conclusions: IPS Empress inlays and onlays demonstrated to be successful even in large defects. Neither the absence of enamel margins, nor cuspal replacement significantly affected the quality of the restorations.

Objective: Ceramic inlays are used as esthetic alternatives to amalgam and other metallic materials for the restoration of badly damaged teeth. However, only limited clinical data are available regarding adhesive inlays and onlays with proximal margins located in dentine. In a prospective, controlled clinical study, the performance of IPS Empress inlays and onlays with cuspal replacements and margins below the amelocemental junction was examined., Materials and Methods: Ninety-six IPS Empress fillings were placed in 34 patients by six clinicians. The restorations were luted with four different composite systems. The dentin bonding system Syntac Classic was used in addition to the acid-etch-technique. At baseline and after 6 months, one, two and four years after placement the restorations were assessed by two calibrated investigators using modified USPHS codes and criteria. A representative sample of the restorations was investigated by scanning electron microscopy to evaluate wear., Results: Seven of the 96 restorations investigated had to be replaced (failure rate 7%; Kaplan-Meier). Four inlays had suffered cohesive bulk fractures and three teeth required endodontic treatment. After four years in clinical service, significant deterioration (Friedman 2-way Anova; p < 0.05) was found to have occurred in the marginal adaptation of the remaining restorations. Seventy-nine percent of the surviving restorations exhibited marginal deficiencies, independent of the luting composite. Neither the absence of enamel margins, nor cuspal replacement significantly affected the adhesion or marginal quality of the restorations., Conclusion: After four years, extensive IPS Empress inlays and onlays bonded with the dentin bonding system Syntac Classic were found to have a 7% failure rate with 79% of the remaining restorations having marginal deficiencies.

The aim of this in vitro study was to compare the dentin bond strength and marginal adaptation of directly and indirectly inserted restorations. A conically modified push-out test was designed to consider polymerization shrinkage and facilitate inlay placement. A total of 260 cavities were prepared into disks of freshly extracted human third molars and filled with direct composite resins or with adhesively luted ceramic inlays. Dentin adhesives of the third--(with self-etching primer: ART Bond, Syntac Classic), fourth--(with total etching: Scotchbond Multi-Purpose Plus), and fifth-generation (one-bottle adhesives: Syntac Single Component, Prime & Bond 2.1) were used in combination with one hybrid composite (Tetric) or luting composite (Variolink Low). Control groups did not use an adhesive. Polymerization of the bonding agent was carried out prior to insertion of the filling/inlay or afterwards simultaneously with the composite/luting composite. The thickness of the adhesive layer and luting composite was recorded, and after 7 days of storage and 24 hours of thermocycling (1150 cycles) replicas were made and extrusion testing performed. Fracture modes were determined and replicas were examined regarding marginal adaptation using SEM (X200 magnification). Precuring of the bonding resin increased dentin bond strength independent of the material combination or insertion mode (P < 0.05). In general, third- and fourth-generation dentin adhesives produced better results in bond strength and marginal adaptation than one-bottle systems (P < 0.05). In the third generation, ART Bond achieved significantly higher push-out values than Syntac (P < 0.05), but no better marginal adaptation. Cohesive fractures within the dentin were only observed in the inlay groups with precured resin. Precuring of the bonding resin is an important factor for both direct and indirect restorations. Nevertheless, precuring of the bonding resin prior to insertion of adhesive inlays cannot be recommended clinically, because the 120-micron luting spaces were too large. In simulated cavities, direct composite fillings with precuring achieved bond strengths similar to inlays without precuring. One-bottle adhesive systems performed poorly compared with multi-step adhesives of the third and fourth generation.

Objectives: The aim of this in vitro study was to evaluate various core build-up and luting materials regarding their effect on crack formation of all-ceramic crowns., Methods: Fifty-six freshly extracted sound human third molars were prepared according to a standardized procedure obtaining a circular shoulder of 1.5 mm with all margins located in dentin. Sixty percent of the dentin volume were removed and restored with totally bonded build-up composite resins or resin-modified glass ionomer cements (RMGIC) or compomers. Cast IPS-Empress caps were manufactured and luted with the different materials. For each material group, the volumes of the core build-ups and of the luting cements were determined. The caps were examined for cracks after 1, 3, 6, 9 and 12 months storage in 0.9% saline solution at 37 degrees C., Results: The tested groups revealed no major differences in the percentage of the core build-ups and in the volume of the luting cements. After 12 months only the group with composite resin build-up and luting showed no crack formation. RMGIC/compomer build-up or RMGIC/compomer luting always resulted in cracking of the caps., Conclusions: Within the limits of this study it can be concluded that the hygroscopic expansion of RMGIC/compomer materials led to failure of all-ceramic crowns, when the materials are used for both core build-up or adhesive bonding.