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ORIGINAL ARTICLE
Year : 2016  |  Volume : 5  |  Issue : 1  |  Page : 29-33

A comparative study to evaluate retention of full metal crowns cemented with various luting agents with and without application of dentine conditioners: An in vitro study


Department of Prosthodontics, Sibar Institute of Dental Sciences, Guntur, Andra Pradesh, India

Date of Web Publication18-Mar-2016

Correspondence Address:
Phani Praneetha Boppana
Department of Prosthodontics, Sibar Institute of Dental Sciences, Guntur - 522 509, Andra Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2277-8632.178975

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  Abstract 

Aim: The aim of the study is to assess the effect of dentin conditioners and luting cements on the retention of full metal crowns.
Materials and Methods: Sixty recently extracted caries free molar teeth were prepared using airotor hand piece mounted to a surveyor with a custom made jig, to obtain a standardized 26° total convergence and 4 mm of axial height. Individual crowns were fabricated using base metal alloy. Thus prepared specimens were divided into six groups: 1) Two groups with no dentin conditioning (Control groups A and B), 2) Two groups, dentin conditioned with 10% polyacrylic acid conditioner (First test groups C and D), and 3) Two groups, dentin conditioned with 17% Ethylenediaminetetraacetic acid (EDTA) (Second test groups E and F). Groups A, C, and E were cemented with conventional glass ionomer whereas Groups B, D, and F were cemented with resin-modified glass ionomer. De-cementation was done using universal testing machine at a cross head speed of 1 mm/min after 48 hours of cementation. The obtained results were analysed using One-way analysis of variance (ANOVA) and Post hoc test.
Results: The mean retentive (tensile) strength of Group A specimens was 2.26 ± 0.15 MPa, Group B specimens was 2.71 ± 0.15 MPa, Group C specimens was 12.26 ± 0.67 MPa, Group D specimens was 14.28 ± 1.47 MPa. Similarly, Group E specimens was 5.23 ± 0.62 MPa, and Group F specimens was 7.36 ± 0.51 MPa.
Conclusion: Within the limitations of the study, retentive (tensile) strength required to dislodge the metal crowns was higher with the combination of resin-modified glass ionomer luting cement and 10% polyacrylic acid dentin conditioner.

Keywords: Conventional glass ionomer, dentin conditioner, resin-modified glass ionomer, retentive strength


How to cite this article:
Anne G, Manne P, Kadiyala KK, Chiramana S, Oliganti SH, Boppana PP. A comparative study to evaluate retention of full metal crowns cemented with various luting agents with and without application of dentine conditioners: An in vitro study. J NTR Univ Health Sci 2016;5:29-33

How to cite this URL:
Anne G, Manne P, Kadiyala KK, Chiramana S, Oliganti SH, Boppana PP. A comparative study to evaluate retention of full metal crowns cemented with various luting agents with and without application of dentine conditioners: An in vitro study. J NTR Univ Health Sci [serial online] 2016 [cited 2022 Jan 20];5:29-33. Available from: https://www.jdrntruhs.org/text.asp?2016/5/1/29/178975


  Introduction Top


Retention is an important factor for long term clinical success of crowns. The smear layer formed on prepared teeth serves as a contaminant and prevents adequate penetration of luting agent into the tooth surface, which in turn affects the retention of crowns. Conditioning of the surfaces to remove the smear layer and, thereby, promoting the bond strength has been proposed. The purpose of this study was to evaluate the effect of dentin conditioners and luting cements on the retentive strength required to dislodge the full metal crowns cemented to prepared teeth with controlled surface areas and high convergence angles.


  Materials and methods Top


Sixty recently extracted caries free intact human molar teeth were prepared using airotor hand piece mounted to a surveyor with a custom made jig [Figure 1] to obtain a standardized 26° total convergence [1],[2] and 4 mm of axial height. [3] Impressions were then made with polyvinyl siloxane using putty reline technique and were poured with type IV die stone. Wax patterns were prepared with a flat occlusal surface by attaching round sprue wax as a loop to facilitate the connection of metal crown to universal testing machine. Wax patterns [Figure 2] were invested, burnout and casting procedures were performed using base metal alloy in a conventional way. Castings were divested and checked for seating discrepancies and later finishing of the crowns was done [Figure 3].
Figure 1: Airotor hand piece mounted to surveyor using custom made jig

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Figure 2: Wax pattern for copings with loop

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Figure 3: Finished copings with loop

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Total samples (60) were divided into six groups based on the total surface area of the teeth, with 10 samples in each group. Crowns of Groups A and B (Control groups) were cemented with conventional glass ionomer and resin modified glass ionomer cement, respectively, without using dentin conditioner. Crowns of Groups C and D (First test groups) were cemented with conventional glass ionomer and resin modified glass ionomer, respectively, after the prepared teeth dentin was conditioned with 10% polyacrylic acid. Crowns of Groups E and F (Second test groups) were cemented with conventional glass ionomer and resin modified glass ionomer, respectively, after the prepared teeth dentin was conditioned with 17% Ethylenediaminetetraacetic acid (EDTA). After 48 hours, de-cementation of all the specimens was done using universal testing machine at a cross head speed of 1 mm/min [Figure 4] and [Figure 5].
Figure 4: Positioning of specimen in UTM for testing

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Figure 5: Crown separated from tooth upon tensile force application

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  Results Top


The tensile strength values for Group A specimens was 2.26 ± 0.15 MPa. This was significantly lower than that of Group B specimens, which was 2.71 ± 0.15 MPa. The tensile strength values for Group C specimens was 12.26 ± 0.67 MPa which was significantly lower than that of Group D specimens, i.e.,14.28 ± 1.47 MPa. The mean retentive strength of Group E specimens was 5.23 ± 0.62 MPa which was significantly lower than that of Group F specimens, i.e., 7.36 ± 0.51 MPa.

The one-way analysis of variance (ANOVA) analysis [Table 1] showed a significant difference between the mean tensile strengths among the six groups compared and the difference between them was found to be statistically significant (P = 0.000). It is inferred that retentive tensile strength values required to dislodge the metal crowns were higher for the crowns cemented with resin-modified glass ionomer cement.
Table 1: Comparison of statistical values


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Among the all specimens cemented with resin-modified glass ionomer cement, the specimens (D Group) that were conditioned with 10% polyacrylic acid showed higher retentive (tensile strength when compared to that of 17% EDTA conditioned specimens (F Group) [Table 2]. And on the whole the conditioned specimens (Groups D and F) showed higher retentive strength values than the unconditioned groups (Control groups A and B) [Figure 6].
Figure 6: Graphical representation of comparison between mean tensile strengths of six groups

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Table 2: Mean tensile strengths


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  Discussion Top


The clinical success of fixed prostheses is heavily dependent on the cementation procedure apart from tooth preparation and casting procedures. [4] A Study by Walyon et al., listed un-cemented restorations as the third leading cause of prosthetic replacement with failure occurring after only 5.8 years of service. Although the establishment of optimal resistance and retention forms in the tooth preparation is of primary importance. [5] Durable bond of restorative material to dentin plays an undisputedly pivotal role in a successful dental restorative treatment. To have a durable bond and to improve the wetting of tooth surface with luting agent, the prepared tooth surface should be free of smear layer. The procedure of removal of smear layer is called dentin conditioning. Even though there are large formulations of dentin conditioners available in the market as there is proven compatibility of polyacrylic acid conditioner (10%) with glass ionomer luting cement and with known advantages of EDTA (17%) compared to acid conditioners, these two conditioners were selected to test along with the most commonly used cements like conventional and resin-modified glass ionomer luting cements. According to Blomtof J et al., the concentration of EDTA should be between 15% and 24% to obtain an acceptable smear removing and collagen-exposing effect within a clinically acceptable time period.

Yim et al., [6] conducted a study on freshly extracted human molars prepared for a standardized crown preparation with 26° total convergence 4 mm axial height using custom-made pantograph. Twelve teeth were prepared for each test condition (144 teeth total). According to this study, relative retentive strengths of cementing agents were in the order of resin cement > resin-modified glass ionomer cement > glass ionomer cement > zinc phosphate cement. The retentive strength value of resin-modified glass ionomer cement (2.96 ± 0.18 MPa) was higher than conventional glass ionomer cement (2.36 ± 0.20 MPa) without conditioning of the tooth surface.

Tay et al., [7] examined the ultrastructure and bond strength of a conventional glass ionomer cement to sound dentin that was conditioned with various techniques. The teeth were tested for tensile bond strength and Scanning Electron Microscope (SEM) evaluation. The study concludes by saying that added pre-treatment dissolves the smear layer, creates a zone of partially demineralized dentin, and allows the polyacrylic acid to interact with dentin via the intermediate layer which might be responsible for increased bond strength (14.0 ± 3.0 MPa) compared to control group.

Ergin and Gemalmaz [8] conducted a study to evaluate the retentive properties of different luting cements on base and noble metal copings to short and over-tapered preparations. Eighty recently extracted caries free mandibular premolars of similar size were selected. Tooth preparation had 33 ° angle of convergence. The occlusal surfaces were made flat with an axial wall height of 3 mm and were prepared entirely in dentin. The results of the study showed that retentive force required to dislodge the crowns were higher with resin-modified glass ionomer cement (381.02 N) compared to value of conventional glass ionomer cement (220.71 N).

Mauro et al., [9] conducted a study to evaluate the effect of pre-conditioning step using different dentin conditioners on the retentive strength of resin-modified glass ionomer luting cement to dentin. The dentin surface was conditioned with 10% polyacrylic acid and resin-modified glass ionomer cement was used for luting. The retentive strength value was higher i.e, 11.30 ± 1.24 MPa compared to control group (no dentin conditioning).

Askary and Nassif [10] conducted a study to evaluate the effect of pre-conditioning step using different dentin conditioners on the retentive strength of resin-modified glass ionomer to dentin. The dentin surface was conditioned with EDTA and blot dried and resin-modified glass ionomer cement is applied. According to this study 18.87% EDTA (11.9 ± 4.4 MPa), reported significantly higher bond strength than resin-modified glass ionomer cement without dentin conditioning (5.5 ± 2.2 MPa).

In the present study, 60 extracted teeth were prepared to receive full metal crowns; total specimens were divided into six groups with 10 in each group. Two groups are taken as control groups without dentin conditioning, in other two groups dentin was conditioned with 10% polyacrylic acid before cementation with conventional and resin-modified glass ionomer cement, respectively, in the last two groups dentin was conditioned with 17% EDTA before cementation of crowns with conventional and resin-modified glass ionomer cement respectively. All the specimens were then subjected to testing using instron testing machine. The retentive strength value of resin-modified glass ionomer cement after dentin conditioning with 10% polyacrylic acid was 14.28 ± 1.47 MPa. That was the highest value obtained when compared to all other evaluated groups.


  Conclusion Top


The combination of luting agents and dentin conditioners showed increased crown retentive strength values compared to control groups tested. The combination of resin-modified glass ionomer cement with 10% polyacrylic acid dentin conditioner showed 5 times increase and with 17% EDTA showed 3 times increase in retentive strength values compared to control group.

Though dentin conditioning improved retentive tensile strength with both conventional and resin-modified glass ionomer cement, more detailed clinical trials have to be performed to suggest its use in regular clinical practice.

 
  References Top

1.
Mitchell CA, Pintado MR, Gear L. Retention of adhesive cement on the tooth surface after crown cementation. J Prosthet Dent 1999;81:668-77.  Back to cited text no. 1
    
2.
Chen CC, Huang TH. Effect of conditioners on bond durability of resin composite to Nd: YAP laser irradiated dentin. Dent Mater J 2006;25:463-9.  Back to cited text no. 2
    
3.
Abreu A, Loza MA, Elias A. Effect of metal type and surface treatment on in vitro tensile strength of copings cemented to minimally retentive preparations. J Prosthet Dent 2007;98:199-207.  Back to cited text no. 3
    
4.
Diaz-Arnold M, Marcos A. Vargas. Current status of luting agents for fixed prosthodontics. J Prosthet Dent 1999;81:135-41.  Back to cited text no. 4
    
5.
Shillingburg HT. Fundamentals of Fixed Prosthodontics. Preparations for Full Veneer Crowns. 3 rd ed. Kimberly Drive, Quintessence Publishing Co. in, 1997. p. 119-23.  Back to cited text no. 5
    
6.
Yim NH, Rueggeberg FA, Caughman WA. Effect of dentin desensitizers and cementing agents on retention of full crowns using standardized crown preparations. J Prosthet Dent 2000;83:459-65.  Back to cited text no. 6
    
7.
Tay FR, Smales RJ, Ngo H. Effect of different conditioning protocols on adhesion of a GIC to dentin. J Adhes Dent 2001;3:153-67.  Back to cited text no. 7
    
8.
Ergin S, Gemalmaz D. Retentive properties of five different luting cements on base and noble metal copings. J Prosthet Dent 2002;88:491-7.  Back to cited text no. 8
    
9.
Mauro SJ, Sundfeld RH, Bedran-Russo AK. Bond strength of resin-modified glass ionomer to dentin: The effect of dentin surface treatment. J Minim Interv Dent 2009;2:45-53.  Back to cited text no. 9
    
10.
Askary FS, Nassif MS. The effect of the pre-conditioning step on the bond strength of nano-filled resin-modified glass-ionomer to dentin. Eur J Dent 2011;5:150-6.  Back to cited text no. 10
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
 
 
    Tables

  [Table 1], [Table 2]



 

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Abstract
Introduction
Materials and me...
Discussion
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