Microhardness of class II composite resin restorations with different matrices and light positions

Kays, Benjamin T.; Sneed, W D; Nuckles, Douglas B.

doi:10.1016/0022-3913(91)90285-5

Cited by 17 publications

(14 citation statements)

References 8 publications

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“…Metal matrix bands only allow light irradiation from the occlusal direction, and they block light from flat surfaces and lightreflecting wedges; therefore, they may impair polymerization at gingival margins. However, one study observed higher hardness values at the gingival margin using a metal matrix band compared to a transparent band (Kays, Sneed & Nuckles, 1991). In this study, the curing light was directed from an angle towards the matrix band, thus allowing for a reflection of the curing light; and the best results were observed using a front surface mirror as a matrix.…”

Section: Discussionmentioning

confidence: 89%

Influence of Curing Methods and Matrix Type on the Marginal Seal of Class II Resin-based Composite Restorations In Vitro

Hofmann

Hunecke

2006

Operative Dentistry

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Selection of photo-curing protocol (high intensity vs soft-start) and matrix type (transparent vs metal) did not influence the margin quality and marginal seal of Class II resin-based composite restorations. SUMMARYThis study determined the influence of light curing protocols and matrix type on the margin quality and marginal seal of Class II resin-based composite restorations.In extracted human molars, box-shaped MOD cavities with 1 mm wide interproximal bevels were prepared with cervical margins located at least 1 mm coronal to the cemento-enamel junction. The prepared teeth were mounted in a jig featuring artificial training teeth that served as adjacent teeth. A contoured sectional metal matrix band was placed in one interproximal area, and a section of a contoured transparent matrix band was placed in the opposite interproximal area. Both were kept in position using 98Operative Dentistry margin quality before and after TC was analyzed in SEM using the replica technique, and the marginal seal was determined using the dye penetration test (50% AgNO 3 , 2 hours) at the end of the study.The matrix type did not significantly influence the quality and seal of the respective margins. For the complete restoration margin, one of the high intensity protocols (APO) produced a higher percentage of "continuous margin" compared to pulse delay irradiation after TC and lower percentages of "marginal opening" compared to halogen standard irradiation before and after TC. Halogen step irradiation produced a superior marginal seal compared to pulse delay curing at the occlusal margins; equivalent results were observed for all curing modes at the cervical margins. Neither a general advantage of soft-start irradiation nor a general disadvantage of high intensity curing was confirmed.

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Section: Discussionmentioning

confidence: 89%

Influence of Curing Methods and Matrix Type on the Marginal Seal of Class II Resin-based Composite Restorations In Vitro

Hofmann

Hunecke

2006

Operative Dentistry

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“…It could be hypothesized that the metal matrix holds enough oxygen in the form of metal oxides to significantly inhibit composite polymerization along its surface or that reaction heat is taken up by the matrix. On the other hand, Kays, Sneed and Nuckles (1991) showed that metal matrices show a higher degree of polymerization than clear matrices. Metal matrices seem to reflect more light than clear matrices, which leads to a higher degree of polymerization.…”

Section: Discussionmentioning

confidence: 99%

Curing Capability of Halogen and LED Light Curing Units in Deep Class II Cavities in Extracted Human Molars

Hasler

Zimmerli

Lussi

2006

Operative Dentistry

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SUMMARYClass II cavities were prepared in extracted lower molars filled and cured in three 2-mm increments using a metal matrix. Three composites (Spectrum TPH A4, Ceram X mono M7 and Tetric Ceram A4) were cured with both the SmartLite PS LED LCU and the Spectrum 800 continuous cure halogen LCU using curing cycles of 10, 20 and 40 seconds. Each increment was cured before adding the next. After a sevenday incubation period, the composite specimens were removed from the teeth, embedded in selfcuring resin and ground to half the orofacial width. Knoop microhardness was determined 100, 200, 500, 1000, 1500, 2500, 3500, 4500 and 5500 µm from the occlusal surface at a distance of 150 µm and 1000 µm from the metal matrix. The total degree of polymerization of a composite specimen for any given curing time and curing light was determined by calculating the area under the hardness curve.Hardness values 150 µm from the metal matrix never reached maximum values and were generally lower than those 1000 µm from the matrix. The hardest composite was usually encountered between 200 µm and 1000 µm from the occlusal surface. For every composite-curing time combination, there was an increase in microhardness at the top of each increment (measurements at 500, 2500 and 4500 µm) and a decrease towards the bottom of each increment (measurements at 1500, 3500 and 5500 µm). Longer curing times were usually combined with harder composite samples. Spectrum TPH composite was the only composite showing a satisfactory degree of polymerization for all three curing times and both LCUs.Multiple linear regression showed that only the curing time (p<0.001) and composite material (p<0.001) had a significant association with the Clinical RelevanceKnoop hardness testing showed that the new generation of light-emitting diodes (LED) have enough power to cure composites in the same time as light curing units (LCU). The composite material and curing time have a significant association with the degree of polymerization.

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“…• The 1.5 mm increments used to place the composite resin in this study • The use of extracted teeth for cavity preparations rather than using other synthetic material (metal blocks) 6,9 • The type and positioning of the light-curing unit • The week-long storage of the specimens • Employment of 1000 cycles of thermocycling.…”

Section: Resultsmentioning

confidence: 99%

“…the material cured from the occlusal surface had minimal hardness at the gingival surface, but substantially greater hardness at the occlusal surface." 6 No statistically significant difference in microhardness was found at any depth of composite restorations when either the bulk or incremental insertion techniques were used. 7 Szep et al 4 suggested, "The highest surface hardness of composite resin was related to transparent matrices.…”

mentioning

confidence: 86%

The Effect of Various Placement Techniques on the Microhardness of Class II (Slot) Resin Composite Restorations

Moosavi

Abedini²

2009

The Journal of Contemporary Dental Practice

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Aim:To analyze the influence of various placement techniques on Vickers microhardness of Class II cavities restored using resin composite in different depths and layers. Methods and Materials:Sixty-four standardized Class II cavities (5.0 × 3.0 × 1.5 mm 3 ) were prepared in sound human, maxillary premolars. The cavities were divided into four experimental groups (n=16) according to the composite placement technique used: incremental technique using a Palodent matrix (IP), incremental technique using a transparent matrix (IT), centripetal technique using a Palodent matrix (CP), and the centripetal technique using a transparent matrix (CT). The cavities were restored with Single Bond, Z100 composite resin system. After 24 hours of storage in envelopes in an amber-colored box, the restorations were finished, polished, and kept for one week before conducting a hardness test. The microhardness test was carried out using a 0.5 kg load for 20 seconds at different depths and layers of proximal surfaces. Statistical analysis was done using a t-test, ANOVA, and a Tukey's test (α=0.05). Results:In contrast, the matrix bands, the methods of composite insertion, had a significant effect on hardness. The greatest surface hardness of resin composite was related to the use of the centripetal technique and a transparent matrix (p<0.05). With regard to cavity depths, the hardness at the top surface was significantly greater, followed by the middle and bottom cavity depths. A greater hardness was obtained in the mesial-distal direction within the external layer compared with the middle and internal layers using the centripetal method (p<0.05). Conclusion:The kind of matrix and filling technique could have a significant effect on surface microhardness. The top surface had the greatest hardness in comparison to different depths. In the centripetal technique, the external layer of the proximal wall had greater hardness than the other layers.Clinical Significance: While the microhardness of all of the experimental placement techniques in the different depths and layers was within a

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Microhardness of class II composite resin restorations with different matrices and light positions

Cited by 17 publications

References 8 publications

Influence of Curing Methods and Matrix Type on the Marginal Seal of Class II Resin-based Composite Restorations In Vitro

Influence of Curing Methods and Matrix Type on the Marginal Seal of Class II Resin-based Composite Restorations In Vitro

Curing Capability of Halogen and LED Light Curing Units in Deep Class II Cavities in Extracted Human Molars

The Effect of Various Placement Techniques on the Microhardness of Class II (Slot) Resin Composite Restorations

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