Marginal breakdown of fired ceramic inlays cemented with glass polyalkenoate (ionomer) cement or resin composite

Clinical Outcomes and Quantitative Margin Analysis of a Universal Adhesive Using a Randomized Clinical Trial over Three Years

The effectiveness of a universal adhesive applied in different application modes for the preparation of Class V composite restorations was evaluated both clinically and by quantitative marginal analysis (QMA). In each of the 22 patients, four non-carious cervical lesions (NCCL) were restored with Filtek^™ Supreme XTE (3M). The adhesive Scotchbond^™ Universal (SBU, 3M) was applied in self-etch (SE), selective-enamel-etch (SEE) or etch-and-rinse (ER) modes. The etch-and-rinse adhesive OptiBond^™ FL (OFL, Kerr) served as a control. The restorations were clinically evaluated (FDI criteria) after 14 days (BL), 6, 12, 24, and 36 months. Additionally, QMA was conducted on all restorations of 11 randomly selected patients. The FDI criteria and marginal gap were statistically compared between the groups at each recall as well as for the time periods between recalls. The cumulative failure rate was non-significantly higher in the OFL group when compared to all of the SBU groups. Marginal adaptation in the OFL and SBU-SE/ER groups was significantly decreased (BL-36 m, p: 0.004) in comparison to the SBU-SEE group (BL-36 m, p: 0.063). More marginal gaps were found in the OFL group than in the SBU-SEE (BL to 36 m, p: 0.063-0.003) and SBU-ER (24/36 m, p: 0.066/0.005) groups as well as in the SBU-SE group when compared to the SBU-SEE (12-36 m, p_i ≤ 0.016) and SBU-ER (24/36 m, p: 0.055/0.001) groups. SBU-SEE performed most effectively. The clinical evaluation and QMA corresponded, yet QMA detected group differences earliest after 6 months and is thus a valuable extension to clinical evaluations.

Three-body wear of luting composites and influence of the ACTA wheel material

The aim of the study was to investigate the wear of luting materials (Variolink Esthetic LC/DC, Multilink Automix, Panavia V5 paste) compared to a resin composite (Tetric EvoFlow) with an ACTA-machine (three-body-wear simulator) using steel and 3D-printed polymer wheels. Wear was measured (software Match3D) and statistically analyzed (ANOVA). Worn surface was examined with a field-emission-scanning-electron-microscope. Finite element analysis was carried out to analyze differences in the mechanical stress of the two different sample wheels. Using the steel wheel, Variolink Esthetic DC exhibited significantly less wear than Tetric EvoFlow after 200,000 cycles (p=0.037). Luting composites on polymer wheels exhibited significantly lower wear values compared to the steel wheels (p<0.001). Finite element analysis showed higher stresses for the steel wheel compared to the polymer wheel. Mechanical properties of the sample wheels had a high influence on wear properties. Dual- or auto-polymerizing materials seem to have a small advantage over the light-curing materials.

Is Optical Coherence Tomography a Potential Tool to Evaluate Marginal Adaptation of Class III/IV Composite Restorations In Vivo?

OBJECTIVE

Margin analysis of Class III and IV composite restorations in vitro and in vivo occurred by scanning electron microscopy (SEM) and optical coherence tomography (OCT). The results were compared and related to clinical evaluation.

METHODS AND MATERIALS

Eight Class III composite restorations were imaged in vitro using OCT and SEM. The margins were analyzed quantitatively. OCT signals were verified by assignment to the criteria perfect margin, gap, and positive/negative ledge. In vivo quantitative margin analysis of Class III/IV composite restorations made of the micro-hybrid composite Venus combined with the self-etch adhesive iBond Gluma inside (1-SE) or etch-and-rinse adhesive Gluma Comfort Bond (2-ER) (all Heraeus Kulzer) was carried out using OCT and SEM after 90 months of clinical function. The results were compared with clinical evaluation (US Public Health Service criteria; marginal integrity, marginal discoloration).

RESULTS

In vitro, the correlation between OCT and SEM was high for all four margin criteria (Kendall tau b [τ_b] correlation: 0.64-0.92, p_i≤0.026), with no significant differences between OCT and SEM (p_i≥0.63). In vivo, a moderate correlation was observed (τ_b: 0.38-0.45, p_i<0.016). Clinically, the cumulative failure rate in the criterion marginal integrity was higher for the 1-SE group (baseline 90 M, p=0.011). Similarly, OCT and SEM detected higher percentages of the criterion gap in the 1-SE group (p: 0.027/0.002), in contrast to perfect margin. Both, gap and perfect margin ranged widely between 0.0% and 88.7% (OCT) and between 0.0% and 89.0% (SEM).

CONCLUSION

Despite the positive selection bias after 90 months with only a few patients left, quantitative margin analysis allows for differentiation between the two adhesives at this specific date. OCT in particular offers the possibility to evaluate marginal integrity directly in vivo.

Cementation of Glass-Ceramic Posterior Restorations: A Systematic Review

Aim. The aim of this comprehensive review is to systematically organize the current knowledge regarding the cementation of glass-ceramic materials and restorations, with an additional focus on the benefits of Immediate Dentin Sealing (IDS). Materials and Methods. An extensive literature search concerning the cementation of single-unit glass-ceramic posterior restorations was conducted in the databases of MEDLINE (Pubmed), CENTRAL (Cochrane Central Register of Controlled Trials), and EMBASE. To be considered for inclusion, in vitro and in vivo studies should compare different cementation regimes involving a “glass-ceramic/cement/human tooth” complex. Results and Conclusions. 88 studies were included in total. The in vitro data were organized according to the following topics: (micro)shear and (micro)tensile bond strength, fracture strength, and marginal gap and integrity. For in vivo studies survival and quality of survival were considered. In vitro studies showed that adhesive systems (3-step, etch-and-rinse) result in the best (micro)shear bond strength values compared to self-adhesive and self-etch systems when luting glass-ceramic substrates to human dentin. The highest fracture strength is obtained with adhesive cements in particular. No marked clinical preference for one specific procedure could be demonstrated on the basis of the reviewed literature. The possible merits of IDS are most convincingly illustrated by the favorable microtensile bond strengths. No clinical studies regarding IDS were found.

Clinical evaluation of indirect composite restorations at baseline and 36 months after placement

This study determined the differences in clinical performance between materials for indirect composite restorations based on Ormocer (Admira) and nano-hybrid resin composite (Grandio), both at baseline and 36 months after placement. Modified USPHS criteria were used to analyze the degree of quality. Marginal integrity was assessed 36 months after placement, whereupon, the restorations fabricated from Grandio achieved an Alpha 1 score of 70.7% and an Alpha 2 score of 29.3%. The Wilcoxon test revealed a statistically significant difference in the evaluation of marginal integrity (p = 0.003), anatomic form of the marginal step (p = 0.025) and discoloration of the margins (p = 0.014) at baseline and after 36 months. For Admira, the Wilcoxon test showed statistically significant differences in the evaluation of surface texture (p = 0.025), anatomic form of the complete surface (p = 0.034), anatomic form of the marginal step (p = 0.008), marginal integrity (p = 0.002) and discoloration of the margins (p = 0.008) at baseline and after 36 months. According to the number of restorations awarded the Alpha 1 score (excellent), the overall success rates for marginal integrity were 70.7% for Grandio and 71.8% for Admira; both were evaluated 36 months after placement. The results have shown that the indirect restorations were acceptable after 36 months, which indicates a 100% success rate. Over 36 months, no statistically significant differences were noted between the two materials. Indirect resin composite restorations represent a good therapy choice for severely damaged teeth.

Edge strength of indirect restorative materials

OBJECTIVES

To evaluate the edge strength and fracture patterns of different all-ceramic and indirect composite materials used in prosthodontic applications.

METHODS

Fourteen rectangular-shaped samples (2-2.5 mm thick) were prepared of each of the following materials: BelleGlass NG (Kerr) (BG), fibre-reinforced BelleGlass/EverStick (Kerr/Stick Tech Ltd.) (BGES), Vita Mark II (Vita Zahnfabrik) (VMII), bilayered IPS e.max Ceram/CAD (Ivoclar-Vivadent) (Ceram/CAD), bilayered IPS e.max Ceram/ZirCAD (Ivoclar-Vivadent) (Ceram/ZirCAD) and unilayered IPS e.max CADLT (Ivoclar-Vivadent) (CADLT). Each group was further subdivided into seven subgroups (n=2) corresponding to different edge distances at which samples were loaded. Samples were tested with an edge strength machine (CK10, Engineering Systems, Nottingham, UK) using a diamond Vickers indenter. The force-to-failure (N) was recorded and four readings were obtained per sample. The mode of failure was analysed microscopically. One-way ANOVA was used to detect differences in edge strength among the groups and correlation and regression analyses were used to detect the correlation between distance of loading and failure force.

RESULTS

The mean values of edge strength (N) were 94.1 (11.2) for BG, 134.4 (10.9) for BGES, 50.5 (8.9) for VMII, 54.4 (7.5) for Ceram/CAD, 53.2 (8.4) for Ceram/ZirCAD and 69.1 (9.1) for CADLT. Significant (p<0.05) strong positive linear correlations were found between the force-to-failure and edge distance among all groups. Three patterns of failure were identified: surface indentation without visible cracking, surface indentation with visible cracking and chipping.

CONCLUSIONS

Indirect composite materials had better edge fracture behaviour than all-ceramic materials. The addition of fibres enhanced the performance of the resin-composite material. Fracture strength increased as the distance from the edge increased. Edge fracture was restricted to the veneer material in bilayared systems and therefore a stronger veneer material is recommended.

Correlation of in vitro fatigue data and in vivo clinical performance of a glassceramic material

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.

Tensile Bond Strength and Flexural Modulus of Resin Cements—Influence on the Fracture Resistance of Teeth Restored with Ceramic Inlays

The mechanical properties of resin cement can influence the fracture resistance of teeth restored with ceramic inlays. In general, cement with a higher elastic modulus resulted in a tooth/ceramic inlay that had a higher fracture resistance.

Influence of bond quality on failure load of leucite- and lithia disilicate–based ceramics

STATEMENT OF PROBLEM

The long-term survival of bonded ceramic restorations for posterior teeth is a clinical concern. The durability of the bond between the ceramic and dentin during clinical service is a factor in the load-bearing capacity of the restoration.

PURPOSE

This study aimed to evaluate the effect of interfacial bonding quality on the interface failure initiation loads of 2 all-ceramic systems.

MATERIAL AND METHODS

One leucite-reinforced ceramic, IPS Empress (E1), and 1 lithia disilicate glass-ceramic, IPS Empress 2 (E2), were used to form disks 8.5 mm in diameter, with an approximate 1.35-mm total thickness (n=45). The ceramic specimens were fabricated in a manner that simulated their clinical application. The E1 specimens were fabricated using the staining technique, and the E2 specimens were made using a layering technique. Completed disks of each ceramic system were divided into 3 subgroups (n=15) that were subsequently cemented using 1 of 3 bonding conditions (Control, Cer, Sub). The control group followed ideal bonding protocol, whereas groups Cer and Sub had bonds that were compromised between the cement and the ceramic (Cer) or the substrate and the cement (Sub). All luted specimens were loaded at the center with a 10-mm-diameter ball indenter at a crosshead speed of 0.01 mm/min in a universal testing machine. Intermittent loads were applied in increasing increments of 50 N until a fracture could be observed in the ceramic substrate by transillumination with x2.6 optical magnification. The maximum load applied prior to crack observation was recorded as the failure initiation load. Survival analytical methods were used to determine differences between groups.

RESULTS

The characteristic fracture initiation loads ranged from 223.5 to 760.6 N. Group E2 had the greatest mean observed load to failure (715.6 N), which was significantly greater than group E1 (P<.001). For both the E1 and E2 ceramic systems, the control groups had significantly greater mean fracture initiation loads than either of the interface-inhibited Cer and Sub groups.

CONCLUSIONS

Poor bond quality at either the ceramic-cement or dentin-cement interface can significantly reduce the fracture initiation load-bearing capacity of ceramic disks bonded to compliant dentin-like substrates. For the E2 ceramic material, disruption of the ceramic-cement interface had a more detrimental effect on the load-bearing capacity of the simulated restoration than the disruption of the cement-dentin interface.

Ceramic inlays bonded with two adhesives after 4 years

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%.

Clinical performance of bonded leucite-reinforced glass ceramic inlays and onlays after eight years

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.

In vitro wear simulation measurements of composite versus resin-modified glass ionomer luting cements for all-ceramic restorations

BACKGROUND

Although composite cements are generally indicated for cementation of all-ceramic restorations, some manufacturers of dental cements propose that resin-modified glass ionomers (RMGIs) may be used for cementation of high-strength ceramic restorations.

PURPOSE

This study was undertaken to compare the in vitro abrasion and attrition wear of two dual-cure cements (in dual-cure and self-cure modes) and two RMGI cements when placed between ceramic and enamel to simulate the margin of a restoration.

METHODS

Rectangular fragments of pressed ceramic (Empress 2) were cemented between the halves of bovine incisors sectioned mesiodistally, using one of the following materials: RelyX ARC, Variolink II, RelyX Luting, or ProTec CEM. The two resin cements were tested in dual-cure and self-cure modes. A three-body wear test was performed in the new Oregon Health Sciences University (OHSU) oral wear simulator (100,000 cycles; abrasion load: 20 N; attrition load: 90 N). Degree of conversion of resin cements was determined by Fourier transform infrared spectroscopy. Results were analyzed by analysis of variance and Tukey's test (p = .05). Epoxy replicas of wear specimens were observed in the scanning electron microscope.

RESULTS

No significant differences in abrasion wear (RelyX ARC dual-cure: 11 +/- 4.4 microm; RelyX ARC self-cure: 17 +/- 7.0 microm; Variolink dual-cure: 14 +/- 8.6 microm; Variolink self-cure: 23 +/- 10.7 microm) or attrition wear (RelyX ARC dual-cure: 18 +/- 6.4 microm; RelyX ARC self-cure: 31 +/- 4.5 microm; Variolink dual-cure: 32 +/- 6.8 microm; Variolink self-cure: 39 +/- 15.9 microm) were found between activation modes of the resin cements. ProTec CEM (32 +/- 8.7 microm) showed abrasion similar to that of Variolink II and RelyX ARC self-cure. Resin-modified glass ionomers showed more attrition wear than the resin cements (ProTec CEM: 62 +/- 13.0 microm; RelyX Luting: 69 +/- 7.1 microm). RelyX ARC showed a similar degree of conversion for both activation modes (dual-cure: 70 +/- 4.3%; self-cure: 68 +/- 1.2%), but Variolink II had a higher degree of conversion in dual-cure mode (67 +/- 0.5% vs 60 +/- 1.0%). Cement wear was accompanied by marginal breakdown and increased surface roughness of enamel and ceramic.

CONCLUSIONS

The activation mode of resin cements did not influence their wear resistance. The RMGIs underwent higher attrition wear than the resin cements.

CLINICAL SIGNIFICANCE

Increased submargination associated with marginal breakdown and increased roughness of the surrounding structures may be expected when ceramic inlays are cemented with resin-modified glass ionomers.

Modified Class II open sandwich restorations: evaluation of interfacial adaptation and influence of different restorative techniques

The sandwich technique with resin-modified glass ionomer cement (RMGIC) has been proposed to relieve the contraction stresses of direct resin composite (RC) restorations. The aim of this study was to evaluate the interfacial adaptation to enamel and dentin of modified Class II open RMGIC/RC sandwich restorations and the influence of different light curing techniques and matrix bands. Forty box-shaped Class II fillings were placed in vivo in premolars scheduled for extraction after one month. In groups I and II, a metal matrix was used; RC was inserted with horizontal (group I) and diagonal (group II) increments and cured with indirect/direct light. Group III was performed as group II, but a transparent matrix was used. Group IV was as group II, but with a separating liner between RMGIC and RC. Group V was a closed sandwich restoration. Interfacial quality was studied using SEM replica technique. Gap-free interfacial adaptation to enamel was observed for RMGIC in 70%, for RC in 70% and to dentin for RMGIC in 81%, for RC in 56%. No significant differences were seen between the experimental groups. At the cervical margins, RMGIC showed significantly better adaptation to enamel than RC, 74% and 42%, respectively. In conclusion, the investigated restorations showed a high percentage of gap-free interfacial adaptation in vivo. Interfacial adaptation to dentin and to cervical enamel was significantly better for RMGIC than for RC.

Interface gap size of manually and CAD/CAM-manufactured ceramic inlays/onlays in vitro

OBJECTIVES

To determine the fit of ceramic inlays manufactured using a recently introduced CAD/CAM-system (Decim) and of two types of laboratory-made heat-pressed ceramics (IPS Empress and Opc).

MATERIALS AND METHODS

Extracted human premolars were prepared to receive mesio-occlusodistal (MOD) ceramic inlays, for which 10 Denzir, 10 IPS Empress, and 10 Opc were fabricated. The Denzir restorations were produced by the manufacturer of the CAD/CAM-system, and the IPS Empress and Opc by student dental technicians. Before luting the internal fit on the diestone models and on the premolars was determined using replicas. After luting on the premolars with a resin composite the marginal and internal fit were measured. The values were analyzed statistically using ANOVA and Scheffe's test at a significance level of p<0.05.

RESULTS

Before luting there were no significant differences (p>0.05) in the internal gap width between the three systems studied when placed on their matching diestone models. When placed on the premolars a significant difference (p<0.01) in the internal fit was seen between Empress and Opc before luting, whereas there were no significant differences (p>0.05) between Empress and Denzir and between Opc and Denzir. Between the diestone models and the premolars there were significant differences (p<0.01) in the internal fit, except for IPS Empress. After luting there were no significant differences (p>0.05) between IPS Empress and Denzir, whereas the marginal gap width was significantly wider (p<0.001) for Opc than for IPS Empress and Denzir. The internal fit was significantly (p<0.001) wider for Opc than for IPS Empress, whereas there were no significant differences (p>0.05) between IPS Empress and Denzir or between Opc and Denzir.

CONCLUSION

After luting there were only slight differences in the fit between the restorations fabricated using the three different manufacturing techniques and ceramics. Therefore, long-term follow-up studies are needed to assess the clinical significance of the slight differences between the three systems.

Direct resin composite inlays/onlays: an 11 year follow-up

OBJECTIVES

The aim of this study was to present an 11-year assessment of direct resin composite inlays/onlays.

METHODS

One-hundred Class II direct resin composite inlays and 34 direct resin composite restorations were placed in 40 patients. The restorations were evaluated clinically, according to modified USPHS criteria, annually over a 11-year period.

RESULTS

Of the 96 inlays/onlays and 33 direct restorations evaluated at 11 years, 17. 7% in the inlay/onlay group and 27.3% in the direct restorations group were assessed as unacceptable. The differences in longevity were not statistically significant. The main reasons for failure for the inlays/onlays and direct restorations were fracture (8.3 and 12. 1%, respectively), occlusal wear in contact areas (4.2 and 6.1%, respectively) and secondary caries (4.2 and 9.1%, respectively). Eight of the non-acceptable inlays/onlays and five of the direct restorations were replaced, while the other ones were repaired with resin composite. Unacceptable wear was observed in occlusal contact areas of six restorations, in patients who were severe bruxers. For the other restorations occlusal wear was not found to be a clinical problem and no difference was observed between the inlays/onlays and direct composite restorations. The marginal adaptation of the inlays/onlays was still good at the end of the study. Ditching was only observed in a few inlays. A higher failure rate was observed in molar teeth than in premolar teeth.

CONCLUSIONS

Good durability was observed for the direct resin composite inlay/onlay technique. Excellent marginal adaptation and low frequency of secondary caries in patients with high caries risk were shown. No apparent improvement of mechanical properties was obtained by the secondary heat treatment of the inlays. Also, the difference in failure rate between the resin composite direct technique and the inlay technique was not large, indicating that the more time-consuming and expensive inlay technique may not be justified. The direct inlay/onlay technique is recommended to be used in Class II cavities of high caries risk patients with cervical marginal placed in dentin.

Clinical performance of pressed ceramic inlays luted with resin-modified glass ionomer and autopolymerizing resin composite cements

STATEMENT OF PROBLEM

Several in vitro studies have been published showing the incapability of the chemical cure of dual-cured resin composite luting agents to compensate for absence of visible light activation.

PURPOSE

This study evaluated and compared pairs of Empress ceramic inlays luted with 2 chemical-cured luting agents: a resin-modified glass ionomer cement and a resin composite within individual patients.

MATERIAL AND METHODS

Seventy-nine ceramic inlays were placed in class II cavities in 29 patients. In each patient half of the inlays were luted with a resin-modified glass ionomer cement and the other half with a chemical-cured resin composite cement. The inlays were evaluated clinically, according to modified USPHS criteria, at baseline, after 6 months, and 1 and 2 years.

RESULTS

No failed inlays were observed during the 2-year follow-up. A slight ditching of the cement margins was observed in both luting groups. No significant difference was seen between the 2 luting techniques.

CONCLUSION

IPS Empress inlays luted with both chemical-cured luting agents functioned satisfactorily in the short-term follow-up. Longer observation periods are necessary to evaluate the long-term clinical behavior of both luting techniques.

IPS Empress inlays and onlays after four years--a clinical study

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.

Mechanical properties of dental luting cements

STATEMENT OF PROBLEM

Dental luting cements fail by microcrack formation and bacterial ingress or by gross failure and crown dislodgment. Both of these failure modes are related to mechanical properties and deformation.

PURPOSE

This study evaluated those mechanical properties of cements. METHODS AND MATERIAL. Elastic modulus for 8 representative cements (zinc phosphate, polycarboxylate, glass ionomer, encapsulated glass ionomer, resin-modified glass ionomer, resin composite, and adhesive resin composite) was measured by using a nondestructive technique and evaluated for cement type and storage time (1 hour, 1 day, 1 week, 1 month, 1 year) by 2-way ANOVA (P <.05). Compressive properties (proportional limit, resilience, and toughness), ultimate strengths (compressive, diametral tensile, and flexural), and flexural toughness were determined and evaluated by 2-way ANOVA for 2 crosshead testing rates (5 and 0.5 mm/min) and cement type (P <.05).

RESULTS

Cements varied with respect to elastic moduli, compressive proportional limit, compressive resilience, compressive strength, compressive toughness, diametral tensile strength, flexural strength, and flexural toughness. Storage time affected the elastic moduli of different materials in different ways. Elastic moduli of polycarboxylate and glass ionomer cements increased over time, whereas the other materials changed little after the first day. Crosshead rate only significantly affected compressive proportional limit and resilience.

CONCLUSIONS

Luting cements differed considerably with respect to mechanical properties.

The effect of pretreatment with an oxalic acid solution on marginal adaptation to enamel in vivo

STATEMENT OF PROBLEM

New acids such as oxalic acid have been introduced as a conditioning agent in the total-etch technique. There is concern about long-term retention of the acid on enamel in relation to the superficial etch effect.

PURPOSE

This in vivo study evaluated the marginal adaptation to enamel conditioned with either and oxalic acid solution or a phosphoric acid with SEM replica technique.

MATERIAL AND METHODS

Twenty-four patients received one of each of three class III restorations. Two cavity preparations were pretreated with aluminum nitrate/oxalic acid/glycine solution 1 of the Gluma 2000 system. The first cavity was primed and sealed with Gluma 2000 solution 2, the second cavity with Gluma 3 and 4. The third cavity was conditioned with phosphoric acid (Gluma 1) and sealed with the bonding resin Gluma 4. All three cavities were restored with a hybrid resin composite (Pekafill). At baseline and after 1 year, replica impressions were made to study the margins with SEM. Semiquantitative analysis of the enamel interfaces was performed (x200 and x1000 magnifications). Marginal quality of the three restorative systems were compared and tested intraindividually.

RESULTS

The three restorations exhibited good enamel marginal adaptation and a high percentage of gap-free margins at baseline, 96% to 97% of the total length of margins investigated. Marginal quality decreased significantly after 1 year for all three groups. Gap-free margins were observed in 81% to 85% of the marginal length. No significant differences were found among the groups.

CONCLUSION

Despite a less pronounced etch pattern created by conditioning of enamel with the oxalic acid solution, a good enamel marginal quality was observed at both evaluation times, comparable to the marginal adaptation of the phosphoric acid conditioned cavities.

Fired ceramic inlays: a 6-year follow up

OBJECTIVES

The aim of this study was to evaluate feldspathic ceramic inlays luted with dual-cured resin composite or glass polyalkenoate (ionomer) cement (GIC) during a 6-year follow-up.

METHODS

One-hundred and eighteen Class II fired feldspathic ceramic inlays were placed in 50 patients. In each patient half of the inlays were luted with a dual-cured resin composite and the other half with a conventional glass ionomer cement. The inlays were evaluated clinically, according to modified USPHS criteria, at baseline, after 6 months and then annually over a 6-year period.

RESULTS

Of the 115 inlays evaluated at 6 years, 12% in the resin composite group and 26% in the GIC group were assessed as having failed. The main reason for failure in both groups was partial fracture or total loss of the inlays. Secondary caries was found to be associated with three inlays in one high caries risk patient. One inlay was replaced because of postoperative sensitivity.

CONCLUSION

A relatively high and increasing failure rate was observed over the 6-year period of the study. The failure rate was more pronounced in the GIC group.

Filler content and gap width after luting of ceramic inlays, using the ultrasonic insertion technique and composite resin cements. An in vitro study

The effect of ultrasonic insertion on the filler content and the gap width for two brands of composite resin luting agents, intended for luting with the ultrasonic insertion technique, were studied after MOD ceramic inlays (Cerec) had been placed. In addition, the internal and marginal gap widths were determined after MOD ceramic inlays (Celay) bad been luted on extracted premolars with this technique. No statistically significant differences (P > 0.05) were observed for either brand between the filler content obtained from the internal surfaces, from the excess luting agent, or from the luting agent as delivered. There were no statistically significant differences (P > 0.05) between the final internal and marginal gap widths when the two brands of luting agent were compared with each other. Except for the final occlusal and internal gap widths obtained for the inlays luted with the Sono-Cem luting agent, no statistically significant differences (P > 0.05) were observed between the gap widths at the different locations determined. Thus, the ultrasonic insertion technique used did not significantly influence the filler ratio of the hybrid luting agents studied. Judged by the findings in this study, the properties of luting agents seem to greatly influence the final marginal and internal gap widths.

Marginal breakdown of 5-year-old direct composite inlays

OBJECTIVES

The marginal fit of tooth-coloured inlays luted with composite resin luting materials has been considered to be the weak link of the inlays. The marginal breakdown of 5-year-old direct composite resin inlays was evaluated by scanning electron microscopy.

METHODS

Replica impressions were made of the occlusal, axial-proximal and accessible cervical-proximal margins of 21 inlays and the marginal quality was quantified.

RESULTS

More than 84% of the total investigated length of the enamel/luting composite agent-luting composite/composite inlay interfaces revealed gap free margins. Proximal margins showed the largest breakdown at the enamel/composite resin interface, while the occlusal margin interfaces showed only a slight difference between the interfaces. The composite inlay and the luting composite resin showed a similar degree of wear in more than 50% of the evaluated marginal length. Medium gap width varied between 60 microns for the occlusal and axial-proximal and 87 microns for the cervical-proximal margins, with a range of 7.6-266 microns.

CONCLUSIONS

The direct composite inlays investigated showed good marginal integrity after 5 years in clinical service.

The teaching of all-ceramic restorations in Scandinavian dental schools: a survey

The study was designed to survey the curricular requirements, types of clinical experience, and materials/ techniques used in teaching programs for all-ceramic restorations in Scandinavian dental schools. All 13 dental schools responded. Ten offered some clinical experience to pre-doctoral students, but only one required one all-ceramic restoration. The departments of fixed prosthodontics had the main teaching responsibility. All-ceramic crowns were taught at 9, veneers at 7, and inlays/onlays at 10 dental schools. A wide range of different teaching concepts, materials, and views on indications and contraindications was reported. It appears as if all-ceramic restorations are regarded as experimental by the teaching institutions, although the dental industry and some practitioners strongly recommend these types of restorations.

Ceramic inlays (Cerec) cemented with either a dual-cured or a chemically cured composite resin luting agent. A 2-year clinical study

On the basis of the criteria of the California Dental Association (CDA), 66 CAD/CAM-manufactured ceramic class-II inlays (Cerec) were compared intraindividually after they had been cemented with either a chemically cured or a dual-cured composite resin luting agent in 27 patients. Plaque and gingival conditions, the overall time consumption for producing each inlay, and the frequency of postoperative sensitivity were also evaluated. There was no statistically significant difference between the two luting agents with regard to the properties evaluated. One inlay was replaced owing to fracture of the restored tooth just before the 24-month re-examination. After 2 years excellent CDA ratings were obtained for color in 92% of the remaining 65 inlays. The corresponding figures for surface and for anatomic form were 100% and 85%, respectively. For margin integrity 85% of the 33 inlays cemented with the dual-cured luting agent and 88% of the 33 inlays cemented with the chemically cured luting agent were rated excellent after 2 years.

Resin-modified glass ionomers for luting posterior ceramic restorations

OBJECTIVES

Until recently, esthetic inlay restorations in posterior teeth have been limited to cavities surrounded by enamel. Dentin adhesive systems in combination with luting composites and light-cured resin-modified glass ionomer cements offer a possibility for bonding ceramic inlays to cavities when the cervical margin is in dentin. This study was designed to compare in vitro marginal integrity of ceramic inlays bonded to dentin to restorations placed in cavities with margins located entirely in the enamel.

METHODS

In the present in vitro study, the sealing abilities of a dentin bonding agent/luting composite combination (Syntac/Dual Cement, Vivadent) and resin-modified glass ionomers (Photac Fil, Photac Bond, ESPE; Dyract, De Trey Dentsply; Fuji II LC, GC Dental Industrial Corp.; and Vitremer, 3M Dental Products) used as luting agents in cavities extending beyond the cemento-enamel junction, were compared to the sealing abilities of a conventional luting composite (Vita Cerec Duo Cement, Vita) in cavities within sound enamel. SEM analysis and dye penetration were performed to evaluate marginal integrity at the cervical cavity margins.

RESULTS

The dentin bonding agent/luting composite combination (Syntac/Dual Cement) rendered a marginal seal within the dentin similar to the quality obtained with the conventional luting procedures within sound enamel. When three out of the five resin-modified glass ionomers were used as luting agents (Dyract, Fuji II LC and Vitremer), the results were comparable to those reported for the dentin bonding agents and the conventional method.

SIGNIFICANCE

Light-cured resin-modified glass ionomer cements may be considered as an alternative to dentin bonding agents when the cavity margins of ceramic inlay restorations are within the dentin. However, further studies, e.g., wear resistance, must be performed.