Clinical evaluation of ceramic inlays and onlays fabricated with two systems: five-year follow-up.

This study evaluated the five-year clinical performance of ceramic inlays and onlays made with two systems: sintered Duceram (Dentsply-Degussa) and pressable IPS Empress (Ivoclar Vivadent). Eighty-six restorations were placed by a single operator in 35 patients with a median age of 33 years. The restorations were cemented with dual-cured resin cement (Variolink II, Ivoclar Vivadent) and Syntac Classic adhesive under rubber dam. The evaluations were conducted by two independent investigators at baseline, and at one, two, three, and five years using the modified United States Public Health Service (USPHS) criteria. At the five-year recall, 26 patients were evaluated (74.28%), totalling 62 (72.09%) restorations. Four IPS restorations were fractured, two restorations presented secondary caries (one from IPS and one from Duceram), and two restorations showed unacceptable defects at the restoration margin and needed replacement (one restoration from each ceramic system). A general success rate of 87% was recorded. The Fisher exact test revealed no significant difference between Duceram and IPS Empress ceramic systems for all aspects evaluated at different recall appointments (p>0.05). The McNemar chi-square test showed significant differences in relation to marginal discoloration, marginal integrity, and surface texture between the baseline and five-year recall for both systems (p<0.001), with an increased percentage of Bravo scores. However, few Charlie or Delta scores were attributed to these restorations. In conclusion, these two types of ceramic materials demonstrated acceptable clinical performance after five years.

Enamel wetness effects on bond strength using different adhesive systems.

OBJECTIVE: To evaluate, through the application of different dentin bonding systems, the influence of wetness on shear bond strength in enamel. METHODS: This study evaluated three etch-and-rinse adhesive systems (Scotchbond MP [used with and without primer]; Singlebond; and Prime&Bond 2.1) and two self-etching adhesive systems (Clearfil SE Bond; and Xeno IV). Flat bovine enamel surfaces were either air-dried for 30 seconds or blotted with absorbent paper after acid-etching for the conventional bonding agents or before the application of self-etching bonding agents. The resin composite EsthetX was bonded to flat surfaces that had been treated with one of the adhesives, following the manufacturer's instructions. After being stored in water at 37°C for one week, bonded specimens were broken in shear. Data were evaluated with two-way analysis of variance (ANOVA) and Student-Newman-Keuls tests (α=0.05). For comparing each condition individually, regardless of the adhesive or wetness condition, a one-way ANOVA and a Student-Newman-Keuls test (α=0.05) were applied. RESULTS: The two-way ANOVA showed significant differences among adhesive systems. An interaction effect was also observed (p<0.05), but wetness did not influence shear bond strength (p=0.98). The one-way ANOVA showed that the all-in-one adhesive was the only material influenced by the presence of water at the enamel's surface. CONCLUSION: The all-in-one adhesive behaved differently depending on whether the enamel surface was dry or wet.

Three-year evaluation of the ART approach in Class III and V restorations in permanent anterior teeth.

This study evaluated the survival of class III and V restorations using the atraumatic restorative treatment (ART) approach in permanent anterior teeth, after 3 years. A total of 151 restorations were performed in 60 patients. After 3 years, 107 restorations (47 patients) were evaluated. Data were analyzed using exact 95% confidence interval. A total of 97 restorations (91% with 95% CI = 83-99), 76 class III (92% with 95% CI = 82-100) and 21 class V (88% with 95% CI = 77-98) were classified as successful. The survival rate of the ART approach in class III and V restorations in permanent anterior teeth was considered high.

Effect of light curing method on volumetric polymerization shrinkage of resin composites.

Volumetric polymerization shrinkage of three resin composites (Suprafil, Z100 and Filtek P60) was determined using four light curing methods: method 1: continuous output with conventional intensity light; method 2: continuous output with higher intensity light; method 3: ramp output and method 4: pulse-delay output. Five disc-shaped specimens were prepared from each material for each curing method. Specimen weight was determined with an analytical electronic hydrostatic balance in air and in water before and after curing. Specific gravity values were then determined. Volumetric polymerization shrinkage was calculated using mathematical formulas. Mean volumetric polymerization shrinkage ranged from 1.882 (.015)% to 2.169 (.028)%. ANOVA indicated significant differences among the materials (p<.05). Light curing methods had no effect on volumetric polymerization shrinkage except for Z-100, where method 2 resulted in significantly higher shrinkage than methods 1 and 4. Suprafil shrunk significantly less than the other two materials in all curing methods.

Clinical evaluation of ceramic inlays and onlays fabricated with two systems: two-year clinical follow up.

This study evaluated the clinical performance of ceramic inlays and onlays made with two systems: sintered (Duceram, Dentsply-Degussa)--D and pressable (IPS Empress, Ivoclar-Vivadent)--IPS after two years. Eighty-six restorations, 44 IPS and 42 D, were cemented into the mouths of 35 patients. Twenty-seven premolars and 59 molars received Class II preparations totaling 33 onlays and 53 inlays. All restorations were cemented with dual-cured resin cement (Variolink II, Ivoclar-Vivadent) and Syntac Classic adhesive under rubber dam. The evaluations were conducted by two independent investigators at the baseline and after one and two years using the modified USPHS criteria. Additionally, radiographs and slides were made. After two years, 100% of the restorations were assessed and all the restorations were considered clinically excellent or acceptable. Among the analyzed criteria, the following received Bravo ratings: marginal discoloration--IPS (31.82%), D (23.81%); marginal integrity--IPS (18.18%), D (11.9%), color match-IPS (4.55%), D (9.52%) and surface texture-IPS (2.27%); D (14.29%). No "Charlie" or "Delta" scores were attributed to the restorations. The results were subjected to the Fisher and McNemar Statistical Tests. No significant differences were noticed between the two ceramic materials. Among the analyzed criteria, only marginal discoloration presented an increased percentage of "Bravo" scores that increased with time for both ceramic materials. Compared with the baseline data, the difference was statistically significant (p < 0.05). No difference was found between inlay and onlay restorations or between restorations placed in premolars or molars. In conclusion, these two types of ceramic materials demonstrated excellent clinical performance after two years.

Clinical evaluation of two "packable" posterior composite resins: two-year results.

The purpose of this study was to evaluate the clinical performance of two "packable" posterior composites: Prodigy Condensable/Optibond Solo-Kerr (PC-OS) and Definite/Etch & Prime-Degussa (D-EP). Thirty-six patients participated in this study. A total of 78 restorations (40 with D-EP and 38 with PC-OS) were made. Each patient received at least two restorations (one of each studied material). The materials were handled according to the manufacturer's instructions. The occlusal adjustments were made at the placement visit. The restorations were finished and polished after 1 week. They were evaluated at baseline, and after 1 year and 2 years by two independent evaluators using the USPHS criteria. Colored slides were made of all the restorations. After 2 years, 34 patients and 74 restorations (38 with D-EP and 36 with PC-OS) were available for evaluation. A total of 50% of PC-OS restorations received A criterion and 50% received B criterion (2.8% color, 11.1% marginal staining, 27.8% superficial staining, 2.8% anatomic form and 5.6% marginal adaptation). For D-EP, 60.5% of restorations received A criterion and 39.5% received B criterion (2.6% color, 5.3% marginal staining, 10.5% superficial staining, 7.9% anatomic form and 13.2% marginal adaptation). The C criterion was observed only for marginal adaptation with D-EP (2 restorations-5.3%). The obtained data were tabulated and statistically analyzed using the Fisher, Chi-square and McNemar tests. After 2 years, PC-OS showed a significant increase in superficial and marginal staining. For D-EP the marginal adaptation and superficial staining became significantly worse than baseline.

Clinical evaluation of two "packable" posterior composite resins.

The purpose of this study was to evaluate the clinical performance of two "packable" posterior composites: Prodigy Condensable (P) (Kerr) and Definite (D) (Degussa). Thirty-six patients participated in the study. A total of 78 restorations were made, 40 with D and 38 with P. Each patient received at least two restorations, one of each studied material. The materials were handled according to the manufacturer's instructions. The restorations were finished and polished after 1 week. They were evaluated at baseline and after 1 year by two independent evaluators using the United States Public Health Service (USPHS) criteria. Colored slides were made of all the restorations. After 1 year, 35 patients and 76 restorations (39 with D and 37 with P) were available for evaluation. All restorations received A criteria except the following ones, which received B criteria: color P (one restoration) and D (one restoration), marginal staining P (three restorations) and D (two restorations), surface staining P (nine restorations) and D (three restorations), anatomic form P (one restoration) and D (three restorations), and marginal adaptation P (one restoration) and D (eight restorations). The obtained data were tabulated and statistically analyzed using the Fisher and McNemar tests. After 1 year, P showed a significant increase in superficial staining. For D, the marginal adaptation became significantly worse than baseline and P. The studied materials can be considered acceptable during this evaluation period. Further evaluations are necessary for a better clinical performance analysis.

Effect of time on the diametral tensile strength of resin-modified restorative glass ionomer cements and compomer.

The aim of this study was to analyze the diametral tensile strengths of three resin-modified restorative glass ionomer cements--Vitremer, Fuji II LC and Photac Fil and one compomer--Dyract. They were tested at 1 hour, 1 day and 1 week. Kratos testing machine was used to load the specimens at a cross-head speed of 0.5 mm/min. The data were analyzed by two-way ANOVA and Tukey's test that showed statistically significant differences among the materials. The tested materials presented an increase in strength from 1 hour to 1 week and were as follows for each material respectively: Vitremer (19.22-27.29), Fuji II LC (23.91-28.67), Photac Fil (19.35-22.86), Dyract (28.83-46.95). Dyract presented the highest strengths.

Fracture strength of weakened human premolars restored with amalgam with and without cusp coverage.

PURPOSE: To determine the effect of cusp coverage with amalgam restorations on the fracture strength of weakened human maxillary premolars. MATERIALS AND METHODS: 30 extracted human maxillary premolars were divided into three groups; Group A (control): uncut teeth, Group B: wide MOD cavities prepared and the pulp chamber's roof removed. The teeth were restored with amalgam without cusp coverage, Group C: same as Group B plus cusp reduction and restored with amalgam. The teeth were included in metal rings with self-curing polystyrene resin and stored in water for 24 hrs. The restorations were refined with rubber points, polished and further stored in water for 24 hrs before being subjected to a compressive axial load in a Universal testing machine at 0.5 mm/min. RESULTS: The mean fracture strength obtained was: Group A: 173.3 Kgf, Group B: 47.3 Kgf and Group C: 127.7 Kgf. All values were statistically significantly different (P < 0.05). The amalgam restoration of weakened human premolars with cusp coverage amalgam significantly increased the fracture strength of the teeth (63%) as compared to teeth restored without cusp coverage. The results showed that cusp coverage with amalgam might be an option for restoring weakened endodontically-treated teeth.

1H-NMR study and structure determination of 4,4- and 4,6-dimers from electrochemical reduction of NADP+.

The products arising from one-electron electrochemical reduction of the coenzyme nicotinamide adenine dinucleotide phosphate (NADP+) have been studied by HPLC chromatography and 1H-NMR spectroscopy. HPLC and NMR analyses have shown seven dimeric species, the most abundant of which (40%) has been isolated and has resulted to be an NADP 4,4-linked dimer. The other two diastereoisomeric 4,4-dimers present for the 25% and 10%, respectively, have been detected in the crude reaction mixture, but have not been isolated. The 4,4-tetrahydrobipyridine structure and the stereochemistry at the ring-ring junction for these three isomers have been determined on the basis of their NMR parameters. Preparative HPLC chromatography also led to two fractions enriched in another four dimers, present in the crude mixture, which turned out to have a 4,6-tetrahydrobipyridine structure. All the chemical shifts and the H,H coupling constants of the 4,4- and 4,6-tetrahydrobipyridine systems have been obtained for the seven compounds. For the most abundant among the 4,4-dimers the NMR analysis also gave the coupling constant values of the ribose-diphosphate chain.

1H-, 13C-, 31P-NMR studies and conformational analysis of NADP+, NADPH coenzymes and of dimers from electrochemical reduction of NADP+.

All H,H, H,P and several C,P coupling constants, including those between C-4' and the vicinal phosphorus atom, have been determined for NADP+, NADPH coenzymes and for a 4,4-dimer obtained from one-electron electrochemical reduction of NADP+. From these data the preferred conformation of the ribose, that of the 1,4-dihydronicotinamide rings, and the conformation about bonds C(4')-C(5') and C(5')-O(5') were deduced. The preferred form of the 1,4- and 1,6-dihydropyridine rings and the conformation about the ring-ring junction were also obtained for all the other 4,4- and 4,6-dimers formed in the same reduction. All the dimers show a puckered structure, i.e., a boat form for the 1,4- and a twist-boat for the 1,6-dihydronicotinamide ring; both protons at the ring-ring junctions are equatorial and have preferred gauche orientation. On the contrary, the reduced coenzyme NADPH displays a planar or highly flexible conformation, rapidly flipping between two limiting boat structures. The conformation of the ribose rings, already suggested for the NADP coenzymes to be an equilibrium mixture of C(2')-endo (S-type) and C(3')-endo (N-type) puckering modes, has been reexamined by using the Altona procedure and the relative proportion of the two modes has been obtained. The S and N families of conformers have almost equal population for the adenine-ribose, whereas for the nicotinamide-ribose rings the S-type reaches the 90%. The rotation about the ester bond C(5')-O(5') and about C(4')-C(5'), defined by torsion angles beta and gamma respectively, displays a constant high preference for the trans conformer beta t (75-80%), whereas the rotamers gamma are spread out in a range of different populations. The values are distributed between the gauche gamma + (48-69%) and the trans gamma t forms (28-73%). The gamma + conformer reaches a 90% value in the case of NADP+ and NMN+. The conformations of the mononucleotides 5'-AMP, NMN+ and NMNH were also calculated from the experimental coupling constant values of the literature.

31P NMR study of daunorubicin-d(CGTACG) complex in solution. Evidence of the intercalation sites.

The interaction of daunorubicin with the self-complementary DNA fragment d(CGTACG) was studied by 31P NMR spectroscopy. The individual phosphates have been assigned for the nucleotide and the complex and signals from bound and free species in slow exchange at 19 degrees C were detected. In solution, the hexanucleotide binds two molecules of daunorubicin, which intercalate in the d(CG) sequence at both ends of the helix. Evidence for local deformations of the backbone at the sites of C5pG6, C1pG2 and G2pT3 phosphates is given. The binding constants for the stepwise equilibrium and the rate of dissociation of the intercalated duplex were also determined.