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Purpose: To evaluate the influence of different resin coating protocols on the fracture strength and wear resistance of a commercial glass-ionomer cement (GIC)., Methods: A new restorative concept [Equia (GC Europe)] has been introduced as a system application consisting of a condensable GIC (Fuji IX GP Extra) and a novel nanofilled resin coating material (G-Coat Plus). Four-point fracture strength (FS, 2 x 2 x 25 mm, 14-day storage, distilled water, 37 degrees C) were produced and measured from three experimental protocols: no coating GIC (Group 1), GIC coating before water contamination (Group 2), GIC coating after water contamination (Group 3). The strength data were analyzed using Weibull statistics. Three-body wear resistance (Group 1 vs. Group 2) was measured after each 10,000 wear cycles up to a total of 200,000 cycles using the ACTA method. GIC microstructure and interfaces between GIC and coating materials were investigated under SEM and CLSM., Results: The highest FS of 26.1 MPa and the most homogenous behavior (m = 7.7) has been observed in Group 2. The coated and uncoated GIC showed similar wear resistance until 90,000 cycles. After 200,000 wear cycles, the coated version showed significantly higher wear rate (ANOVA, P< 0.05). The coating protocol has been shown to determine the GIC fracture strength. Coating after water contamination and air drying is leading to surface crack formation thus significantly reducing the FS. The resin coating showed a proper sealing of GIC surface porosities and cracks. In terms of wear, the coating did not improve the wear resistance of the underlying cement as similar or higher wear rates have been measured for Group 1 versus Group 2.

Purpose: To evaluate the clinical behavior of two different resin composites in Class II cavities over a period of 2 years in a controlled prospective split-mouth study., Methods: 30 subjects received 68 direct resin composite restorations (Grandio bonded with Solobond M: n=36, Tetric Ceram bonded with Syntac: n=32) by one dentist in a private practice. All restorations were replacement restorations, 24 cavities (35%) revealed no enamel at the bottom of the proximal box, in 33 cavities (48%) the proximal enamel width was < 0.5 mm. The restorations were examined according to modified USPHS criteria at baseline, and after 0.5, 1, and 2 years. At each recall, impressions were taken to prepare replicas. Replicas of 44 selected subjects were assessed for marginal quality under a stereo light microscope (SLM) at x130, and 22 replicas were assessed under a SEM at x200., Results: Both recall rate and survival rate were 100% after 2 years of clinical service. No significant difference was found between the restorative materials (P > 0.05; Mann-Whitney U-test). A significant deterioration was found over time for marginal integrity, tooth integrity, restoration integrity and proximal contact (P < 0.05; Friedman test). SLM and SEM analysis of restoration margins only revealed differences in the amount of detectable perfect margins, in favor of Tetric Ceram (P < 0.05). Both materials performed satisfactorily over the 2-year observation period.

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).

This review thoroughly accumulated information regarding new technologies for state-of-the-art light curing of resin composite materials. Visible light cured resin-based composites allow the dentist to navigate the initiation of the polymerization step for each layer being applied. Curing technology was regularly subjected to changes during the last decades, but meanwhile the LED era is fully established. Today, four main polymerization types are available, i.e. halogen bulbs, plasma are lamps, argon ion lasers, and light emitting diodes. Additionally, different curing protocols should help to improve photopolymerization in terms of less stress being generated. Conclusions were: (1) with high-power LED units of the latest generation, curing time of 2 mm thick increments of resin composite can be reduced to 20 seconds to obtain durable results; (2) curing depth is fundamentally dependent on the distance of the resin composite to the light source, but only decisive when exceeding 6 mm; (3) polymerization kinetics can be modified for better marginal adaptation by softstart polymerization; however, in the majority of cavities this may not be the case; (4) adhesives should be light-cured separately for at least 10 seconds when resin composite is applied directly; (5) photocuring through indirect restorations such as ceramics is still a problem, therefore, both dual-cured adhesives and dual-cured composites and resin coating in any way are recommended; and (6) heat generation with high-power photopolymerization units should not be underestimated as a biological problem for both gingival and pulpal tissues.

Purpose: To design an artificial mouth in order to evaluate if a new diagnostic tool (Clinpro Cario Diagnosis) can be used for early detection of secondary caries at resin composite margins in vitro., Methods: 32 intact human third molars received standardized Class-V resin composite restorations (Tetric Ceram bonded with Syntac SC). After storage for 4 weeks at 37 degrees C, teeth were subjected to 5,000 or 10,000 thermocycles (+/- 5 degrees C and +/- 55 degrees C) and polysiloxane impressions were taken. Streptococcus mutans 10449 (SM) was used in a nutrition medium to initiate a secondary caries process. Daily, the teeth were incubated for 2 x 2.5 hours in SM containing nutrition medium followed by 2 x 9.5 hours incubation in artificial saliva. Teeth were investigated after total incubation periods of 4, 6, and 8 weeks. After the different incubation protocols, the restoration margins were evaluated for infection and secondary caries processes in using Clinpro Cario Diagnosis which measures site-specifically the lactic acid production of SM in response to a sucrose challenge. The color signal was read 5 minutes after removal of the diagnostic impression. After thermocycling and biological load cycling, precision polysiloxane impressions were taken and replicas were investigated under a light microscope for gap widths at enamel and dentin margins. Demineralization was evaluated by fluorescence microscopy in using a special FITC filter. The demineralization depths at the cavity margin were calculated with Xpert for Windows using a pixel distance of 5 microm., Results: After the different thermocycling protocols, no differences in gap widths and demineralization depths were found (P > 0.05). After SM incubation, gap widths and demineralization depths were significantly dependent on SM incubation time and previous number of thermocycles (P < 0.05). Lactic acid formations of SM were detectable by Clinpro Cario Diagnosis at dentin cavosurface margins formed after 6 weeks of incubation with SM (P < 0.05).

Purpose: To clinically evaluate two polyacid-modified resin composites (Hytac and Dyract AP) for the restoration of posterior teeth over a 4-year period and to investigate accessible margins by light microscopy., Methods: In a controlled prospective clinical study, 71 cavities (21 occlusal, 41 MO/OD, 9 MOD) in 30 patients were restored with compomers by three dentists. Thirty-eight restorations were placed with the combination OSB/Hytac, the same patients received 33 restorations with Prime&Bond 2.1/Dyract AP. Enamel margins of the cavities were etched with phosphoric acid. At baseline, after 12, 24, and 48 months, the restorations were examined by two independent investigators according to modified USPHS-criteria. Focusing on the 40 restorations available at all recalls, a semi-quantitative margin analysis was carried out at each recall using replicas and light microscopy at x130 magnification., Results: Twenty restorations were not investigated at the 4-year recall (drop-out). After 48 months, 11 restorations (Hytac: n = 8, Dyract AP: n = 3) had to be replaced due to tooth fracture (n = 4), gap formation (n = 5), and adhesive failure (n = 2). Forty restorations were still in function after 4 years (overall failure rate 16%; Hytac: 21%; Dyract: 9%). Between the recalls, statistically significant differences were detected for the criteria marginal integrity (Alpha dropping from 76% at baseline to 32% after 4 years), restoration integrity (Alpha ratings at baseline 99% vs. 40% after 4 years), and occlusion (100% vs. 24%). For the criteria surface roughness (from the 6-month recall) and anatomical shape (after 4 years), a significant difference between the materials was evident in favor of Dyract AP. Except gap-free margins, the predominant criterion in the microscopic analysis at baseline was marginal overhang (24%) and 30% negative step formation after 4 years.

Purpose: To clinically evaluate two different resin-based composites (Solitaire I and Ariston pHc) in order to determine the minimum clinical evaluation time needed to detect critical signs of failure., Methods: In a controlled prospective clinical study, 99 cavities (30 Class I, 69 Class II) in 31 patients were restored (50 Ariston pHc without enamel etching and rubber dam, 49 Solitaire I restorations with total etching and rubber dam) and clinically investigated at baseline, after 6, 12, and 24 months., Results: After 2 years of clinical service, 49 restorations (Ariston pHc: n = 38, Solitaire: n = 11) had to be replaced. The majority of failures occurred after more than 1.5 years. The reasons for replacement were differently distributed in both groups (Ariston pHc: 28 tooth fractures, 3 gap formations, 5 hypersensitivities, 1 bulk fracture, 1 marginal fracture. Solitaire: 5 gap formations, 1 hypersensitivity, 3 bulk fractures, 1 wear of the restorative material, 1 void in the restoration). Forty-four restorations were still in function after 2 years (overall failure rate after 2 years: 14%; Ariston pHc: 17%; Solitaire: 7%; survival analysis algorithm according to Kaplan/Meier). Comparing the materials, no statistical differences were evident except for the criteria "integrity tooth" (= tooth fracture or cracks) and "hypersensitivity" (from the 12-month recall; Mann-Whitney U-test; P< 0.05). In both cases of significant difference, Ariston pHc exhibited inferior results. After 2 years, only three teeth restored with Ariston pHc did not show considerably cracked enamel. The additional marginal analysis showed statistically significant differences for both materials regarding the criteria "perfect margin" (decrease), "gap formation" (increase), and "negative step formation" (increase; P< 0.05; Friedman 2-way ANOVA) between the four recalls. Therefore, a 2-year in vivo evaluation should be recommended prior to marketing a dental restorative material.

Purpose: To evaluate different resin-based composites using a variety of in vitro investigation methods to predict their clinical behavior., Methods: Materials selected for this study were Heliomolar radiopaque (microfilled), Tetric Ceram, Pertac II (minifilled hybrids), Ariston pHc (ion releasing hybrid), and Solitaire I (hybrid with porous fillers). The evaluated in vitro criteria were three-body wear according to the ACTA method, microtensile bond strengths to enamel and dentin, flexural strength (four-point bending strength), flexural fatigue behavior (flexural fatigue limit), and calcium ion release (for Ariston pHc)., Results: Concerning wear resistance, Ariston pHc (20.5 microm after 200,000 cycles) was inferior to the other materials (13.7-15.9 microm). Microtensile bond strengths to dentin were similar for Heliomolar (32.0 MPa), Tetric Ceram (30.4 MPa; both bonded with Syntac Classic), and Pertac II (30.8 MPa; bonded with EBS Multi) being above Solitaire I (22.5 MPa; bonded with Solidbond) being above Ariston pHc (13.2 MPa; bonded with Ariston Liner). Enamel bond strengths for Heliomolar (40.0 MPa), Tetric Ceram (36.5 MPa), and Pertac II (38.9 MPa) were significantly higher than for Solitaire I (26.6 MPa) which was above Ariston pHc (7.2 MPa). Heliomolar, Tetric Ceram, and Pertac II revealed higher micro-TBS to enamel than to dentin, Ariston showed the contrary, and Solitare exhibited no difference between enamel and dentin micro-TBS. Solitaire I exhibited a lower initial flexural strength than the other materials, the computed fatigue strength of the material even dropped to the level of glass ionomer cements (17.9 MPa). Long-term calcium release data for Ariston exhibited a continuously high calcium release becoming lower at the end of the observation beyond 21 months.

Purposes: (1) To evaluate different pre-treatment modes for partial resin-based composite repair using a shear bond strength fatigue design on aged specimens, and (2) to investigate the effect of these pre-treatments on aged and partially replaced Class II resin-based composite restorations., Materials and Methods: (Study 1) 150 composite discs (Tetric Ceram) were light-cured, secondary cured, and stored in water for 365 days. The specimens were randomly assigned to five pretreatment groups (n=30): (1) Roughening with a finishing diamond bur + dentin bonding system (DBS, Syntac Classic), (2) Roughening with a silicon carbide bur + DBS, (3) Roughening with a silicon carbide bur + DBS + Tetric Flow, (4) silica-coating (CoJet) + DBS, and (5) silica-coating + dentin bonding agent + Tetric Flow. The disks were restored with fresh repair composite cylinders and after 24-hour water storage, initial bond strengths (n=10) and fatigue bond strengths (n=20; 5,000 cycles in shear mode) were evaluated and fracture modes determined under a SEM. (Study 2): 40 Class II restorations (EBS Multi/Pertac II) were placed in extracted human third molars. The specimens were stored for 365 days and then replaced partially by removing the proximal box and leaving the occlusal part. The partial repairs (Pertac II) were placed after identical pre-treatment modes A-E (n=8). After thermomechanical loading (100,000 x 50 N, simultaneously x2,500 at 5 degrees C/55 degrees C), marginal quality between old and fresh composite was evaluated by SEM at x200 magnification and dye penetration was observed by light microscopy under x50 magnification., Results: Initial repair bond strengths were significantly higher for the groups with additional application of flowable composite compared to composite only (P<0.05; Mann Whitney U test). Diamond finishing revealed the lowest bond strengths. Fatigue bond strengths exhibited the worst results for Group 1 as well, but were similar for Groups 2-5. In the Class II partial repair simulation, Groups 3 and 5 with additional flowable lining exhibited significantly better marginal quality and significantly lower leakage, whereas the other groups revealed up to 100% separation between aged and freshly applied composite.

Purpose: To describe the potential of adhesive luting procedures with respect to (1) material characteristics and classifications, (2) film thickness, (3) overhang control, (4) bonding to different inlay materials, (5) adhesion to tooth substrates and the problem of hypersensitivities, (6) wear of luting composites, and (7) clinical performance., Materials and Methods: A literature review of relevant studies of various in vitro and in vivo studies enables an overview of possibilities and limitations of adhesively luted indirect restorations., Results: (1) Resin-based composites are the material of choice for adhesive luting. Both material properties and wear behavior of fine particle hybrid-type resin-based composites are superior to other materials. The use of compomers is questionable due to hygroscopic expansion and possible crack formation as proven for IPS Empress caps in vitro and in vivo. (2) Recent luting cements exhibit excellent flow characteristics with mean film thicknesses ranging between 8 microm and 21 microm. The ultrasonic insertion technique is recommended for viscous luting composites or conventional restorative composites utilizing their thixotropic properties. (3) For successful overhang control, good fit of the restoration (during luting) and high radiopacity of the cement (after luting) are indispensable. Overhang control is estimated easier when the ultrasonic insertion technique is applied. (4) The pre-treatments of ceramic inlays using hydrofluoric acid or silica coating result in effective bonding; for pre-treatment of resin-based composite inlays, silica coating is promising as well. (5) Bonding to enamel and dentin is proven clinically acceptable, but it should be performed with multi-step systems providing separate primers and bonding agents producing a perfect internal seal with almost no hypersensitivities. Dual-cured multi-step bonding agents provide the most promising potential. (6) The viscosity and filler content of the resin composite used for luting does not influence the wear characteristics within the marginal luting area in vivo. However, the ultrasonic insertion technique involving high viscosity materials provides enhanced handling characteristics for luting of tooth-colored inlays. (7) Clinical results with tooth-colored inlays and veneers are promising over periods of up to 10 yrs, including use in severely destroyed teeth.