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ORIGINAL ARTICLE
Year : 2010  |  Volume : 28  |  Issue : 4  |  Page : 245-250
 

A comparative study of retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements with stainless steel crowns - An in vitro study


1 Professor & Head, Department of Pedodontics & Preventive Dentistry, Uttar Pradesh Dental College & Hospital, Faizabad Road, Lucknow, Utter Pradesh, India
2 Principal, Professor & Head, Department of Pedodontics & Preventive Dentistry, College of Dental Sciences, Pavilion Road, Davangere - 577004, Karnataka, India
3 Professor, Department of Pedodontics & Preventive Dentistry, Bapuji Dental College & Hospital, Davangere - 577004, Karnataka, India

Date of Web Publication25-Jan-2011

Correspondence Address:
M H Raghunath Reddy
Department of Pedodontics & Preventive Dentistry, Uttar Pradesh Dental College & Hospital, Faizabad Road, Lucknow, Utter Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0970-4388.76150

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   Abstract 

An in vitro study was conducted to compare the retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements using Instron universal testing machine. Thirty preformed and pretrimmed stainless steel crowns were used for cementation on 30 extracted human primary molars which were divided into three groups of 10 teeth in each group. Then the teeth were stored in artificial saliva and incubated at 37°C for 24 h. A load was applied on to the crown and was gradually increased till the crown showed dislodgement, and then the readings were recorded using Instron recorder and analyzed for statistical significance. The surface area of crown was measured by graphical method. The retentive strength was expressed in terms of kg/cm 2 , which was calculated by the equation load divided by area. Retentive strengths of zinc phosphate (ranged from a minimum of 16.93 to amaximum of 28.13 kg/cm 2 with mean of 21.28 kg/cm 2 ) and glass ionomer cement (minimum of 13.69 - 28.15 kg/cm 2 with mean of 20.69 kg/cm 2 ) were greater than that of polycarboxylate cement (minimum of 13.26 - 22.69 kg/cm 2 with mean of 16.79 kg/cm 2 ). Negligible difference (0.59 kg/cm 2 ) of retentive strength was observed between zinc phosphate (21.28 kg/cm 2 ) and glass ionomer cements (20.69 kg/cm 2 ). Glass ionomer cements can be recommended for cementation of stainless steel crowns because of its advantages and the retentive strength was almost similar to that of zinc phosphate cement.


Keywords: Luting cements, retentive strength, stainless steel crowns


How to cite this article:
Raghunath Reddy M H, Subba Reddy V V, Basappa N. A comparative study of retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements with stainless steel crowns - An in vitro study . J Indian Soc Pedod Prev Dent 2010;28:245-50

How to cite this URL:
Raghunath Reddy M H, Subba Reddy V V, Basappa N. A comparative study of retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements with stainless steel crowns - An in vitro study . J Indian Soc Pedod Prev Dent [serial online] 2010 [cited 2019 Jul 22];28:245-50. Available from: http://www.jisppd.com/text.asp?2010/28/4/245/76150



   Introduction Top


The restoration of primary and permanent teeth with advanced carious lesions has been a constant and difficult problem for the dentist, to prevent premature loss of primary teeth and to maintain normal occlusion.

Studies have shown that amalgam, a commonly used restorative material, had to be replaced with stainless steel crowns in 70% of multisurface amalgam restorations. Stainless steel crowns have proved to be efficacious and are relatively easy to use, they have become an important factor in the restoration of hypoplastic, endodontically treated teeth, malformed teeth and fracture teeth to perform their normal function. [1],[2]

In 1950, Humphery introduced preformed or stainless steel crowns, later Helm listed indications for stainless steel crowns in pediatric dentistry.

Many studies have investigated the retention of stainless steel crowns and clinicians have suggested that dental cement alone was responsible for retention of stainless steel crowns on primary molars. [3],[4],[5],[6] Jefferey et al, however, believe that the significant retentive feature is the close adaptation of the metal crown margin to the tooth surfaces in the undercut areas of the prepared teeth. [7] Placement of well-fitted, contoured stainless steel crown on different crown preparations, without cement is not possible because of its insufficient strength to fit on the tooth. Stainless steel crowns have been cemented with zinc phosphate cement,[4],[8],[9] polycarboxylate cement,[4],[5],[8],[9] and zinc oxide eugenol cement, but it would appear that glass ionomer cements, due to their adhesive properties to dentin and enamel and fluoride releasing ability, have definite advantages over the other cements.[5],[10]

So this study was planned to compare the retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements with the stainless steel crowns.


   Materials and Methods Top


The study was conducted in the Department of Pedodontics and Preventive dentistry, Bapuji Dental College and Hospital, Davangere in collaboration with the Department of Metallurgy, Indian Institute of sciences, Bangalore and Department of civil Engineering, B.D.T., Davangere.

Instron universal testing machine: (Instron - 8502) [Figure 1]
Figure 1 :Instron apparatus and specimen

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The specially designed Instron apparatus were used. The applied force was directed parallel to the long axis of the tooth, at a cross head speed of Instron of 0.05 inch/min.

A total of 30 extracted human maxillary first and second mandibular primary molars (two maxillary primary first molars, 10 maxillary primary second molars, six mandibular primary first molars, 12 mandibular primary second molars) were selected for the study. These teeth had sufficient intact tooth structure so that a good crown marginal seal could be obtained on the basis of a good clinical examination. Each tooth was hand scaled and cleaned to remove soft tissue debris and rinsed with deionized water. Each tooth was mounted in self-cure acrylic resin exposing complete crown. The occlusal surfaces of all teeth were reduced uniformly about 1 mm to 1.5 mm. The proximal surfaces were prepared so that contact was broken and all mesial and distal undercuts were removed. All the sharp angles were made rounded. Then pretrimmed and precontoured stainless steel crown (Ion-3M) was fitted on each tooth and crimped, contoured to allow for the best marginal fit achievable on the basis of a thorough examination with an explorer. The crown had two opposing attachments (Begg's brackets) spot welded to facilitate the attachment of the crown removal apparatus. Then 30 teeth were randomly divided into three groups of 10 teeth in each group, i.e., zinc phosphate cement, polycarboxylate cement and glass ionomer cement, respectively [Figure 2].
Figure 2 :Armamentarium

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The cements were manipulated according to the manufacturer's recommendations. They were loaded into the crown and each crown was seated with hand pressure. All excess cement was removed from crown margins. After 10 min, the teeth were stored in prepared artificial saliva and incubated at 37°C for 24 h. Retentive strength was tested using Instron universal testing machine. The machine [Figure 3] was fitted with an Instron recorder. A specially designed apparatus of Instron was used to remove the cemented crowns. Hole was made for each specimen at the base of the mounted teeth with self cure acrylic resin in order to place the specimen in the specially designed Instron apparatus[Figure 4]. A screw was passed through the Instron apparatus and the hole of the each specimen to stabilize the specimen during crown removal and the screw was made tight.
Figure 3 :Specimen mounted on Instron

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Figure 4 :Instron universal testing machine

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The load was applied from zero reading and then gradually increased. The loading was continued until the cemented stainless steel crowns showed first dislodgement during crown removal. The machine was stopped by pressing the button after cemented stainless steel crowns showed first dislodgement and recorded the readings. The specimen was removed and new specimen was placed in the Instron apparatus and the screw was made tight. The same procedure was followed for all the specimens. The applied load was directed parallel to the long axis of the tooth during crown removal. Cross head speed of Instron was 0.05 inch/min. The retentive strength values were recorded, expressed in terms of kg/cm 2 , which was calculated by the formula: load / area.

The surface areas of crowns have been determined by cut opening of the crowns and their surfaces have been developed on graph sheet and the areas of these developed surfaces have been determined by counting the squares on these developed areas.


   Results Top


An in vitro study of three dental cements was performed to test the retention of stainless steel crowns on extracted primary molars using Instron Universal testing machine.

The Wilcoxon Mann-Whitney ' U ' test was performed to compare the retentive strength between each group to see whether there were any significant differences in strengths among the groups.

Kruskal-Wallis one-way analysis of variance was performed to know the difference in retentive strength exhibited by different cements.

The analysis revealed that there were significant differences in retentive strengths of different cements.

The retentive strength of the zinc phosphate, polycarboxylate and glass ionomer cements were ranged from 16.93 to 28.13, 13.26 to 22.69 and 13.69 to 28.15 kg/cm2 respectively. The mean retentive strength with standard deviation for zinc phosphate, polycarboxylate and glass ionomer cements were 21.28 ± 2.91, 16.79 ± 3.28 and 20.69 ± 4.14 kg/cm2 respectively [Table 1] and [Table 2].
Table 1 :Retentive strengths of the cements (kg/cm2)


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Table 2 :Retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements


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The retentive strength of zinc phosphate ranged from 16.93 kg/cm 2 to 28.13 kg/cm2 with an average of 21.28 ± 2.91 kg/cm2. For polycarboxylate cement, the retentive strength ranged from 13.26 to 22.69kg/cm2 with an average of 16.79 ± 3.28 kg/cm2. The results showed that zinc phosphate cement strength was greater than that of polycarboxylate cement and the difference was statistically significant (P<0.05) [Table 3].
Table 3 :Retentive strengths of zinc phosphate and polycarboxylate cements


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The retentive strength of zinc phosphate ranged from 16.93 to 28.13 kg/cm2 with an average of 21.28 ± 2.91kg/cm2. For glass ionomer cement, the retentive strength ranged from 13.69 to 28.15 kg/cm2 with an average of 20.69 ± 4.14 kg/cm2. The mean retentive strength of the glass ionomer cement was lesser than that of phosphate cement, but the difference was not statistically significant [Table 4].
Table 4 :Retentive strengths of zinc phosphate and glass ionomer cements


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The comparison of the retentive strength of polycarboxylate and glass ionomer cements was also assessed. The retentive strength of polycarboxylate cement ranged from 13.26 to 22.69 kg/cm2 with an average of 16.79 ± 3.28 kg/cm2 with an average of 20.69 ± 4.14 kg/cm2. The mean retentive strength of the glass ionomer cement was greater than that of polycarboxylate cement and the difference was statistically significant (P<0.05) [Table 5].
Table 5 :Retentive strengths of polycarboxylate and glass ionomer cements


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The results showed that zinc phosphate cement had better retentive strength than glass ionomer cements but the difference was not statistically significant. Both the zinc phosphate and glass ionomer cements showed better retentive strength than the polycarboxylate cement and the difference was statistically significant (P<0.05).


   Discussion Top


An in vitro study was carried out to compare the retentive strength of the three luting cements.

Zinc phosphate is the oldest of the luting cements used widely for cementation of stainless steel crowns. This cement is generally considered as adequate for clinical crown retention, even though its retentive properties are purely mechanical in nature. It is brittle, has a relatively high solubility in the mouth, and it does not adhere to tooth structure. They do have high compressive strength and are also a potentially caustic substance, to vital pulp tissue due to their low pH.[11],[12]

The use of fluoride releasing cements with the potential for chemical adhesion and mechanical retention helps in retention of the crown. The polycarboxylates form an ionic bond with enamel and dentin and have a higher adhesive strength than the zinc phosphate. [11] Addition of fluoride to this cement results an increase in strength and anticariogenic properties. [13] They also have a somewhat lower compressive strength than that of zinc phosphate cements and are relatively non toxic to vital tissue.[14],[15],[16] The glass ionomer cements are also used because it forms a strong ionic bond to enamel, dentin and nickel chrome alloys providing a high adhesive strength [16],[17],[18],[19],[20] and releases fluoride from the setting cement. It gives a high compressive strength[18],[21],[22] because of the unique composition and structure of Al3+ and Ca2+ ions and polyacrylic acid solution, which is also found to be relatively nontoxic to vital pulpal tissue. [23]

Studies compared the retention of stainless steel crowns with and without cementation (i.e., mechanical retention from the crown alone and retention due to cementation) and they found the retention due to cementation to be far greater than that gained from mechanical retention alone. This clearly shows that the placement of cement is necessary for the placement of stainless steel crowns.[3],[4],[5],[6]

Zinc phosphate, polycarboxylate and glass ionomer cements were used in this study, because these are the commonly used luting cements for cementation of stainless steel crowns in routine clinical practice.

Primary molars were selected for this study because stainless steel crowns are more widely used on primary molars to prevent premature tooth loss and development of future malocclusion.

Pretrimmed and precontoured stainless steel crowns were used in this study because to standardize the surface area of the crowns as in case of other type of crowns trimming is necessary which gives an intra clinician variation in surface area and the specimens were stored in the artificial saliva because it simulates human saliva.

Instron tensometer, Hounsfield tensometer and Instron universal testing machines were used to measure the retentive strength of the cements. Whereas, in the present study, Instron universal testing machine was used because of the easy availability than Instron tensometer and Hounsfield tensometer.

Mathewson found the highest retentive strength with copper phosphate cement than zinc phosphate and polycarboxylate cements, which he attributed to the low pH of the copper cement during the setting reaction and a possible acid etching effect on the tooth creating a better bond between the cement and the tooth. He also speculated that the acidity of the copper cement potentially was harmful to pulp tissues in vital teeth. So in this study, copper phosphate cement was not considered for testing retentive strength. [4]

David R. Myers and Garcia Godoy reported that no significant difference was found between zinc phosphate and polycarboxylate cements in the retention ability of the cements. Whereas in this study, zinc phosphate cement showed better retentive strength than polycarboxylate cement, which was statistically significant (P<0.05). The difference may be due to the fact that zinc phosphate cement lies on mechanical interlocking for its retentive effect and on close physical adaptation for sealing restorative margins, but it does not provide any chemical bonding to tooth or metal surfaces. [8],[9]

Noffsinger et al found that no significant difference between the overall mean retentive forces of the two glass ionomer cements and polycarboxylate cement using preformed crowns fitted to extracted third molar teeth, whereas in this study glass ionomer cement showed better retentive strength than polycarboxylate cement, which was statistically significant (P<0.05). [5] The exact reason for this difference is not known, but it may due to powder - liquid ratio, viscosity and shorter working time. Advantage of the glass ionomer over the zinc polycarboxylate is the fluidity or lower viscosity of the mixed glass ionomer cement. [24] Studies have shown that glass ionomers have higher adhesive strength and form stronger bonds to tooth structure and stainless steel than the polycarboxylate cements. [16],[17],[18],[19],[20]

Polycarboxylates form an ionic bond with enamel and dentin and have a higher adhesive strength than zinc phosphate.[11] The chemical reaction of polycarboxylate cement is by which zinc ions link adjacent poly acrylic acid molecules producing a large cross-linked chelate structure. The poly acrylic acid molecules have the ability to chelate to calcium ions in tooth enamel as well as to stainless steel. This shows that polycarboxylate cements are suitable for cementation of stainless steel crowns. [25],[26]

In the present study, zinc phosphate cement showed better retentive strength than glass ionomer cement. The lesser retentive strength of glass ionomer may be due to the advantage of the cement during initial phase of setting, moisture can adversely affect the hardness of the surface.[27],[28],[29]

From this study, glass ionomer cements can be recommended for cementation of stainless steel crowns. Because these cements have the ability to bond to enamel and base metals, [16],[17],[18],[19],[20] release fluoride from setting cement [21] and are found to be nontoxic to vital pulp tissue. [23] In the present study, the mean retentive strength of zinc phosphate cement was 21.28kg/cm2 and glass ionomer cement showed 20.69 kg/cm2, which was not of much difference. So glass ionomer cements can be recommended for cementation of stainless steel crowns.


   Summary and Conclusion Top


This in vitro study was conducted to compare the retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements using Instron universal testing machine. Thirty preformed and pretrimmed stainless steel crowns were used for cementation on 30 extracted human primary molars.

A load was applied on to the crown and was gradually increased till the crown showed dislodgement, and then the readings were recorded and analyzed for statistical significance. The surface area of crown was measured by graphical method. The retentive strength was expressed in terms of kg/cm2, which was calculated by the equation load divided by area.

From the present study, it can be concluded that:

  • The retentive strength of zinc phosphate cement ranged from a minimum of 16.93 to a maximum of 28.13 kg/cm2 with the mean of 21.28 kg/cm2.
  • The retentive strength of polycarboxylate cement ranged from a minimum of 13.26 to a maximum of 22.69 kg/cm2 with the mean of 16.79 kg/cm2.
  • The retentive strength of glass ionomer cement ranged from a minimum of 13.69 to a maximum of 28.15 kg/cm2 with the mean of 20.69 kg/cm2.
  • The retentive strengths of zinc phosphate and glass ionomer cements were greater than the retentive strength of polycarboxylate cement.
  • Negligible difference (0.59 kg/cm2) of retentive strength was observed between zinc phosphate (21.28 kg/cm2) and glass ionomer cements (20.69 kg/cm2).
  • Glass ionomer cements can be recommended for cementation of stainless steel crowns because of its advantages and the retentive strength was almost similar to that of zinc phosphate cement.


 
   References Top

1.Braff MH. A comparison between stainless steel crowns and multi - surface amalgams in primary molars. ASDC J Dent Child 1975;42:474-8.  Back to cited text no. 1
[PUBMED]    
2.Dawson LR, Simon JE, Taylor PP. Use of amalgam and stainless steel restorations for primary molars. ASDC J Dent Child 1981;48:420-2.  Back to cited text no. 2
    
3.David R Myers. A clinical study of the response of the gingival tissue surrounding stainless steel crowns. J Dent Child 1975;42:33-6.  Back to cited text no. 3
    
4.Mathewson RJ, Lu Kh, Talebi R. Dental cement retentive force comparison on stainless steel crowns. J Calif Dent Assoc 1974;2:42-5.  Back to cited text no. 4
[PUBMED]    
5.Noffsinger DR, Jedrychowski JR, Caputo AA. Effects of polycarboxylate and glass ionomer cements on stainless steel crown retention. Pediatr Dent 1983;5:68-71.  Back to cited text no. 5
    
6.Savide Nl, Caputo AA, Luke LS. The effect of tooth preparation on the retention of stainless steel crowns. ASDC J Dent Child 1979;46:385-9.  Back to cited text no. 6
[PUBMED]    
7.Rector JA, Mitchell RJ, Spedding RH. The influence of tooth preparation and crown manipulation on the mechanical retention of stainless steel crowns. ASDC J Dent Child 1985;52:422-7.  Back to cited text no. 7
    
8.Myers DR, Bell RA, Barenie JT. The effect of cement type and tooth preparation on the retention of stainless steel crowns. J Pedod 1981;5:275-80.  Back to cited text no. 8
[PUBMED]    
9.Garcia Godoy F. Clinical evaluation of the retention of preformed crowns using two dental cements. J Pedod 1984;8:278-81.  Back to cited text no. 9
    
10.Garcia-Godoy F, Bugg JL. Clinical evaluation of glass cementation on stainless steel crown retention. J Pedod 1987;11:339-44.  Back to cited text no. 10
[PUBMED]    
11.Grieve AR. A study of dental cements. Br Dent J 1969;127:405-10.  Back to cited text no. 11
[PUBMED]    
12.Wilson AD. Zinc oxide dental cements in scientific aspects of dental materials. In: Von Fraunhofer JA, editor. 1 st ed. London: Butterworth's; 1975. p. 305.  Back to cited text no. 12
    
13.Tsukiboshi M, Tani Y. Physical properties of a Polycarboxylate cement containing a tannin fluoride preparation. J Prosthet Dent 1984;51:503-8.  Back to cited text no. 13
[PUBMED]    
14.Plant CG. The effect of Polycarboxylate containing stannous fluoride on the pulp. Br Dent J 1973;134:317-21.  Back to cited text no. 14
    
15.Plant CG, Jones DW. The damaging effects of restorative materials. Br Dent J 1976;140:373- 406.  Back to cited text no. 15
[PUBMED]    
16.Plant CG. The use of a glass Ionomer cement in deciduous teeth. Br Dent J 1977;143:271-4.  Back to cited text no. 16
    
17.Hotz P. The bonding of glass Ionomer cements to metal and tooth substrates. Br Dent J 1977;142:41-7.  Back to cited text no. 17
    
18.Kent BE, Wilson AD. The properties of a glass Ionomer comment. Br Dent J 1971;135:322-6.  Back to cited text no. 18
    
19.Prodger TE, Symonds M. ASPA adhesion study. Br Dent J 1977;143:266-70.  Back to cited text no. 19
[PUBMED]    
20.McLean JW. Status report on the Glass Ionomer cements: Council on dental materials and devices. J Am Dent Assoc 1979;99:221-6.  Back to cited text no. 20
[PUBMED]    
21.Crisp S, Ferner AJ, Lewis BG, Wilson AD. Properties of improved glass Ionomer cement formulations. J Dent 1975;3:125-30.  Back to cited text no. 21
[PUBMED]    
22.Wilson AD. Experimental luting agents based on the glass Ionomer cements. Br Dent J 1977;142:117-22.  Back to cited text no. 22
    
23.Tobias RS, Browne RM, Plant CG, Ingrah DV. Pulpal response to a glass Ionomer cement. Br Dent J 1978;144:345-50.  Back to cited text no. 23
    
24.Reisbick MH. Working qualities of glass Ionomer cements. J Prosthet Dent 1981;46:525-30.  Back to cited text no. 24
[PUBMED]    
25.Mizrahi E. The recementation of orthodontic bands using different cements. Angle Orthod 1979;49:239-46.  Back to cited text no. 25
[PUBMED]    
26.Rich JM, Leinfelder KF, Hershay HG. An invitro study of cement retention as related to orthodontics. Angle Orthod 1975;45:219-22.  Back to cited text no. 26
    
27.Klockowski R, Davis EL, Joynt RB, Wieczkowski G Jr, MacDonald A. Bond strength and durability of glass Ionomer cements used as bonding agents in the placement of orthodontic brackets. Am J Orthod Dentofacial Orthop 1989;96:60-4.  Back to cited text no. 27
[PUBMED]    
28.Swartz ML, Phillips RW, Clark HE, Norman RD, Potter R. Fluoride distribution in teeth using a silicate model. J Dent Res 1980;59:1596-603.  Back to cited text no. 28
[PUBMED]  [FULLTEXT]  
29.Swartz ML, Phillips RW, Clark HE. Long term fluoride release from glass ionomer cements. J Dent Res 1984;63:158-60.  Back to cited text no. 29
[PUBMED]  [FULLTEXT]  


    Figures

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

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]


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