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Effects of coronal substrates and water storage on the microhardness of a resin cement used for luting ceramic crowns.

Mendonça LM, Pegoraro LF, Lanza MD, Pegoraro TA, Carvalho RM - J Appl Oral Sci (2014 Jul-Aug)

Bottom Line: The success of cementation depends on the achievement of adequate cement curing.Data were first analyzed by three-way ANOVA that did not reveal significant differences between thirds and occlusal surface (p=0.231).The type of material employed for coronal reconstruction of preparations for prosthetic purposes may influence the cement properties.

View Article: PubMed Central - PubMed

Affiliation: Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil.

ABSTRACT

Unlabelled: Composite resin and metallic posts are the materials most employed for reconstruction of teeth presenting partial or total destruction of crowns. Resin-based cements have been widely used for cementation of ceramic crowns. The success of cementation depends on the achievement of adequate cement curing.

Objectives: To evaluate the microhardness of Variolink® II (Ivoclar Vivadent, Schaan, Liechtenstein), used for cementing ceramic crowns onto three different coronal substrate preparations (dentin, metal, and composite resin), after 7 days and 3 months of water storage. The evaluation was performed along the cement line in the cervical, medium and occlusal thirds on the buccal and lingual aspects, and on the occlusal surface.

Material and methods: Thirty molars were distributed in three groups (N=10) according to the type of coronal substrate: Group D- the prepared surfaces were kept in dentin; Groups M (metal) and R (resin)- the crowns were sectioned at the level of the cementoenamel junction and restored with metallic cast posts or resin build-up cores, respectively. The crowns were fabricated in ceramic IPS e.max® Press (Ivoclar Vivadent, Schaan, Liechtenstein) and luted with Variolink II. After 7 days of water storage, 5 specimens of each group were sectioned in buccolingual direction for microhardness measurements. The other specimens (N=5) were kept stored in deionized water at 37ºC for three months, followed by sectioning and microhardness measurements.

Results: Data were first analyzed by three-way ANOVA that did not reveal significant differences between thirds and occlusal surface (p=0.231). Two-way ANOVA showed significant effect of substrates (p<0.001) and the Tukey test revealed that microhardness was significantly lower when crowns were cemented on resin cores and tested after 7 days of water storage (p=0.007).

Conclusion: The type of material employed for coronal reconstruction of preparations for prosthetic purposes may influence the cement properties.

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Related in: MedlinePlus

Scheme of experimental stages: a) prepared tooth; b) wax relief; c) cementedcrown; d) sectioned crown exhibiting microhardness measurements along the cementline and ceramic thicknesses
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f01: Scheme of experimental stages: a) prepared tooth; b) wax relief; c) cementedcrown; d) sectioned crown exhibiting microhardness measurements along the cementline and ceramic thicknesses

Mentions: Thirty human third molars were embedded with plaster in plastic cylinders with thecementoenamel junction approximately 3 mm above the top of the cylinder. The teeth wereprepared with diamond burs for full-ceramic crowns with a shoulder of 1.2 mm withinternal rounded angles, and axial reduction of 1.5 mm with 6 to 10º convergence anglewas performed. Occlusal reduction was performed resulting in an axial height of 4.0 mm(Figure 1a). They were randomly divided into 3groups (N=10) as follows: Group D- the prepared crown surface was kept in dentin; GroupM- the crowns were sectioned at the level of the cementoenamel junction and the core wasmodeled in acrylic resin DuraLay (Reliance Dental Mfg. Co. Worth, Illinois, USA), castin aluminum-copper alloy, and luted with zinc phosphate (S. S. White Artigos DentáriosLtda., Rio de Janeiro, RJ, Brasil); Group R- the crowns were sectioned as in group M,and filling of the cores was performed with composite resin Filtek® Z250 (3MESPE, St Paul, MN, USA) by the incremental technique. Light irradiation was obtainedfrom a Quartz Tungsten Halogen (QTH) device V.I.P. Junior (Bisco, Schaumburg, IL, USA,500 mW/cm2 ) for 20 s for each increment, and 40 s for the last one. The pulpchambers were cleaned and filled with the same composite resin. The reduction,convergence and height of axial walls followed the same principles described above forGroup D.


Effects of coronal substrates and water storage on the microhardness of a resin cement used for luting ceramic crowns.

Mendonça LM, Pegoraro LF, Lanza MD, Pegoraro TA, Carvalho RM - J Appl Oral Sci (2014 Jul-Aug)

Scheme of experimental stages: a) prepared tooth; b) wax relief; c) cementedcrown; d) sectioned crown exhibiting microhardness measurements along the cementline and ceramic thicknesses
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4126824&req=5

f01: Scheme of experimental stages: a) prepared tooth; b) wax relief; c) cementedcrown; d) sectioned crown exhibiting microhardness measurements along the cementline and ceramic thicknesses
Mentions: Thirty human third molars were embedded with plaster in plastic cylinders with thecementoenamel junction approximately 3 mm above the top of the cylinder. The teeth wereprepared with diamond burs for full-ceramic crowns with a shoulder of 1.2 mm withinternal rounded angles, and axial reduction of 1.5 mm with 6 to 10º convergence anglewas performed. Occlusal reduction was performed resulting in an axial height of 4.0 mm(Figure 1a). They were randomly divided into 3groups (N=10) as follows: Group D- the prepared crown surface was kept in dentin; GroupM- the crowns were sectioned at the level of the cementoenamel junction and the core wasmodeled in acrylic resin DuraLay (Reliance Dental Mfg. Co. Worth, Illinois, USA), castin aluminum-copper alloy, and luted with zinc phosphate (S. S. White Artigos DentáriosLtda., Rio de Janeiro, RJ, Brasil); Group R- the crowns were sectioned as in group M,and filling of the cores was performed with composite resin Filtek® Z250 (3MESPE, St Paul, MN, USA) by the incremental technique. Light irradiation was obtainedfrom a Quartz Tungsten Halogen (QTH) device V.I.P. Junior (Bisco, Schaumburg, IL, USA,500 mW/cm2 ) for 20 s for each increment, and 40 s for the last one. The pulpchambers were cleaned and filled with the same composite resin. The reduction,convergence and height of axial walls followed the same principles described above forGroup D.

Bottom Line: The success of cementation depends on the achievement of adequate cement curing.Data were first analyzed by three-way ANOVA that did not reveal significant differences between thirds and occlusal surface (p=0.231).The type of material employed for coronal reconstruction of preparations for prosthetic purposes may influence the cement properties.

View Article: PubMed Central - PubMed

Affiliation: Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil.

ABSTRACT

Unlabelled: Composite resin and metallic posts are the materials most employed for reconstruction of teeth presenting partial or total destruction of crowns. Resin-based cements have been widely used for cementation of ceramic crowns. The success of cementation depends on the achievement of adequate cement curing.

Objectives: To evaluate the microhardness of Variolink® II (Ivoclar Vivadent, Schaan, Liechtenstein), used for cementing ceramic crowns onto three different coronal substrate preparations (dentin, metal, and composite resin), after 7 days and 3 months of water storage. The evaluation was performed along the cement line in the cervical, medium and occlusal thirds on the buccal and lingual aspects, and on the occlusal surface.

Material and methods: Thirty molars were distributed in three groups (N=10) according to the type of coronal substrate: Group D- the prepared surfaces were kept in dentin; Groups M (metal) and R (resin)- the crowns were sectioned at the level of the cementoenamel junction and restored with metallic cast posts or resin build-up cores, respectively. The crowns were fabricated in ceramic IPS e.max® Press (Ivoclar Vivadent, Schaan, Liechtenstein) and luted with Variolink II. After 7 days of water storage, 5 specimens of each group were sectioned in buccolingual direction for microhardness measurements. The other specimens (N=5) were kept stored in deionized water at 37ºC for three months, followed by sectioning and microhardness measurements.

Results: Data were first analyzed by three-way ANOVA that did not reveal significant differences between thirds and occlusal surface (p=0.231). Two-way ANOVA showed significant effect of substrates (p<0.001) and the Tukey test revealed that microhardness was significantly lower when crowns were cemented on resin cores and tested after 7 days of water storage (p=0.007).

Conclusion: The type of material employed for coronal reconstruction of preparations for prosthetic purposes may influence the cement properties.

Show MeSH
Related in: MedlinePlus