Retention, Marginal Leakage, and Cement Solubility of Israel Lewinstein, DMD, PhDa Provisional Crowns Cemented Nitzan Fuhrer, DMDb Katerina Gelfand, DMDc with Temporary Cement Harold Cardash, BDS, LDS RCS Engd Containing Stannous Fluoride Raphael Pilo, DMDa

Purpose: This in vitro study investigated the (1) retention and microleakage of provisional

crowns cemented with temporary cements to which stannous fluoride (SnF2) was added, and (2) solubility of these cements. Materials and Methods: Provisional crowns were constructed of acrylic resin with shoulder preparations for 12 molars. The crowns were luted

with Tempbond, Tempbond NE, and Freegenol temporary cements, and also with SnF2 added to these cements. Specimens were thermocycled 100 times, stored for 6 days, and immersed in 0.5% basic fuschin. Seven days after cementation, crown removal (retention) tests were conducted. Marginal leakage was assessed using a five-level scale to score dye

penetration. Solubility in water of the cements with and without SnF2 was assessed using cement disks. Results: Freegenol was more retentive than the other cements. The

incorporation of SnF2 significantly increased the retention capacity of Freegenol and Tempbond NE but had no effect on Tempbond. Tempbond showed significantly higher dye

penetration than Freegenol. The addition of SnF2 did not alter the dye penetration of the cements. There were no significant differences in the solubility of the cements. However, the

incorporation of SnF2 increased the solubility of Freegenol and Tempbond NE (P < .001) and Tempbond (P < .01). Conclusion: The addition of SnF2 increased the retention of temporary crowns cemented with Tempbond NE and Freegenol but did not affect the retention of those cemented with Tempbond. The marginal leakage of crowns cemented with the tested

temporary cements with and without the incorporation of SnF2 was similar. However, the addition of SnF2 increased the solubility of the cements. Int J Prosthodont 2003;16:189–193.

ermanent and provisional restorations cemented and mechanical protection for the abutments. A tem- Pwith temporary cement need to provide biologic porary cement must be strong enough to retain the restoration but weak enough to enable removal of the restoration without damage to the abutment.1 a Senior Lecturer, Department of Oral Rehabilitation, The Maurice However, provisional crowns luted with temporary and Gabriela Goldschleger School of Dental Medicine, University of Tel Aviv, Israel. cements are susceptible to cement washout, marginal bInstructor, Department of Oral Rehabilitation, The Maurice and leakage, bacterial infiltration, and caries, especially Gabriela Goldschleger School of Dental Medicine, University of when placed for periods longer than a few weeks. Tel Aviv, Israel. The relatively poor marginal fit and marginal leak- c Student, Department of Oral Rehabilitation, The Maurice and age of provisional crowns made of acrylic resin when Gabriela Goldschleger School of Dental Medicine, University of Tel Aviv, Israel. used over the long term raises the need for temporary dAssociate Clinical Professor, Department of Oral Rehabilitation, cements with antibacterial properties. Evidence in vitro The Maurice and Gabriela Goldschleger School of Dental strongly suggests that materials that release fluoride Medicine, University of Tel Aviv, Israel. have anticariogenic potential.2–6 Swartz et al7 reported Reprint requests: Dr Israel Lewinstein, Department of Oral that the solubility of the intact enamel surface is re- Rehabilitation, The Maurice and Gabriela Goldschleger School of duced by contact with zinc-oxide-eugenol (ZOE) for- Dental Medicine, University of Tel Aviv, Tel Aviv 69978, Israel. Fax: mulations to which sodium fluoride or stannous fluo- + 972-3-6409250. e-mail: [email protected] ride (SnF2) was added and suggested the possibility of In partial fulfillment of the DMD degree of K. Gelfand. imparting anticariogenic properties to ZOE cements.

Volume 16, Number 2, 2003 189 The International Journal of Prosthodontics Provisional Crowns with SF2-Containing Temporary Cement Lewinstein et al

of the teeth were embedded in acrylic resin contained in plastic rings. A standardized crown preparation was adopted to ensure similar tooth reduction. Each tooth was prepared for a complete crown with a 1-mm rounded shoulder. The axial walls were prepared with a convergence angle of 10 degrees using a handpiece clamped to a surveyor.10 Autopolymerizing acrylic a resin (Duralay, Reliance Dental) provisional crowns were fabricated by applying a block of acrylic resin in the doughy stage to each tooth. On setting, the block of acrylic resin was removed and shaped to re- semble a tooth. A layer of approximately 0.5 mm of acrylic was removed from the inner surface of each b crown using a crosscut bur, and a mixture of acrylic resin was placed in the crown. The crown was then firmly seated on the prepared tooth under a load of 50 N. Before final curing, the crown was removed and reseated three times with a 1-minute dwell time to fa- cilitate its removal. Finally, the excess resin was Fig 1 Retentive force test. A steel rod (a) attached to the oc- trimmed, and the relined crowns were stored in water clusal surface of a provisional crown (b) serves as a connector for 24 hours before testing. to the tensile testing machine. A steel rod (dental mandrel for handpiece) with an enlarged tip was attached with acrylic resin to the oc- Table 1 Temporary Cements Tested clusal surface of each provisional crown and paral- Product and Type of Batch lel to the long axis of the tooth, serving as a connec- manufacturer material No. tor to the tensile testing machine (Fig 1). Before cementation, the retention of each crown was tested Tempbond, Kerr Zinc-oxide-eugenol 6-1242 Tempbond NE, Kerr Noneugenol 6-1194 to verify low and similar values of self-retention. The Freegenol, GC Noneugenol 040681 mean value of the retentive force for all crowns with- SnF , Sigma Chemical Stannous fluoride 12H315 2 out cement did not exceed 0.2 ± 0.02 N. Table 1 lists the tested cementing materials. Each crown was ce- mented with three different cements with and with-

Duraphat (Colgate) is a fluoride varnish containing out the addition of SnF2, for a total of six cement 2.26% sodium fluoride (NaF) with a pH of 5.5. The ad- groups, each comprising 12 teeth. The fluoridated ce- dition of Duraphat fluoride varnish to temporary ce- ments were prepared by mixing SnF2 powder with the ments in vitro increased the retentive force of the ce- cement to constitute 0.4% by weight. This concen- ments after 1 hour.8 Duraphat alone or combined with tration was selected after a pilot study in which the temporary cements has also been shown to reduce release of fluoride over 3 months and the setting marginal leakage after 7 days.9 However, the degree properties of the cements were tested. of retention varies with the type of cement. The effect The cements were applied in a thin layer to the of SnF2 on temporary cement retention, microleakage, inner axial walls of the crown. Thirty seconds after and solubility has not been investigated. the start of mixing, each crown was seated on the The objectives of this study were to investigate the prepared tooth, and a static load of 50 N was ap- (1) retention and microleakage of provisional crowns plied for the first minute. Cementation was per- cemented with various temporary cements to which formed at an ambient temperature of 23 ± 1°C.

SnF2 was added, and (2) solubility of temporary ce- Before each cementation, the prepared teeth were ments containing SnF2. The null hypothesis stated that wiped thoroughly with wet gauze to remove rem- there would be no difference in the retention, mi- nants from the previous cementation. After cemen- croleakage, or solubility for the temporary cements tation, specimens were stored in 100% humidity at with and without SnF2. 37°C for 1 hour, thermocycled 100 times (5°C/55°C) with a 10-second dwell time, and then stored in Materials and Methods 100% humidity at 37°C for 6 days. Thermocycling was conducted to simulate thermal stresses and Twelve freshly extracted intact human molars were se- aging of the cemented crowns. Specimens were im- lected and stored in 0.1% thymol solution. The roots mersed in 0.5% basic fuschin solution for 6 hours

The International Journal of Prosthodontics 190 Volume 16, Number 2, 2003 Lewinstein et al Provisional Crowns with SF2-Containing Temporary Cement and then washed, dried, and stored at 100% hu- Table 2 Mean (Standard Deviation) Retention, Dye midity at 37°C. Penetration, and Solubility of Cements Retention Median dye Solubility (% Retention Test Material (N) penetration by weight)

Tempbond 25 (13) 13 0.5 (0.3) On the seventh day, the specimens were mounted on Tempbond + SnF2 29 (13) 12 2.1 (1.2) an Instron testing machine (model 4502). The ce- Tempbond NE 12 (5) 12 0.5 (0.2) Tempbond NE + SnF 35 (18) 9 3.4 (1.6) mented crowns were subjected to tensile dislodgment 2 Freegenol 44 (20) 9 0.7 (0.3) forces using a cross-head speed of 1 mm/min. The re- Freegenol + SnF2 75 (30) 10 4.6 (0.9) tentive force was determined as the maximum force (peak 1) required for crown removal. Data were sub- jected to two-factor analysis of variance (ANOVA), and comparisons of the means were performed by a Bonferroni post hoc test. All hypothesis testing was Where SnF2 was added, it constituted 0.4% of the ce- conducted at the 95% level of confidence. ment weight. The mixed cement was inserted into the holes and smoothed flush with the surface of the Microleakage Test (Dye Penetration) mold. The specimens in the mold were stored for 1 hour at 100% humidity at 37°C and then ejected from After removal of the crowns, microleakage was as- the mold with a plunger. Specimens with visible de- sessed by scoring the extent of dye penetration on the fects were rejected. walls of the prepared tooth and on the inner surface Seventy-two glass bottles were numbered and of the crown. A single operator recorded the mi- weighed. Each specimen was placed in a bottle and croleakage according to a standardized system. reweighed. Twenty milliliters of distilled water was Criteria for evaluation were as follows: added to each bottle, and the stoppered bottles were incubated at 100% humidity and 37°C for 30 days. •0 = no dye penetration The cement specimens were then removed, and the •1 = partial penetration of the shoulder water was evaporated from the bottles in an oven at •2 = complete penetration to the full width of the 95°C for 24 hours. After cooling to room temperature, shoulder the bottles with the residue were reweighed. •3 = dye penetration to the gingival third of the Solubility of the cement was calculated according to axial walls the following formula: •4 = dye penetration beyond the gingival third of the axial walls (M3 – M1)100 M2 – M1 For each tooth, the most severe degree of dye pene- tration was recorded. Since the scores ranged be- where M1 = weight of empty bottle; M2 = weight of tween 0 and 4 for each wall, the maximum score for bottle + specimen; and M3 = weight of bottle + each tooth (four walls) was a possible 16. The final residue. Data were analyzed by a two-factor ANOVA. dye penetration of each cement was calculated as the Comparisons of the means were performed by a median of the scores for each tooth. Bonferroni post hoc test. All hypothesis testing was After the dye penetration assessment, the teeth conducted at the 95% level of confidence. were cleaned of stains and the remnants of the lut- ing cement under running water. The crowns were re- Results lined to verify that the same relationship existed be- tween crown and tooth prior to the next cementation The mean retentive force of the temporary cements and test. Statistical differences in microleakage were ranged from 12 N for Tempbond NE to 44 N for analyzed by the Wilcoxon matched-pairs signed rank Freegenol (Table 2). Statistically significant differ- test at a 95% level of confidence. ences (P < .05) were found between Tempbond NE and the other cements, but not between Tempbond

Solubility Tests and Freegenol (P > .05). The addition of SnF2 signif- icantly increased the retentive force of Tempbond NE A Teflon (DuPont) mold containing 12 cylindric holes (P < .01) and Freegenol (P < .05), with no significant was used to obtain flat disks of cement. The disks were change for Tempbond (P > .05) (Fig 2). There was no 6 mm in diameter and 3 mm thick. Each cement was significant difference in retention between Tempbond mixed according to the manufacturer’s instructions. and Tempbond NE after the addition of SnF2 (P > .05).

Volume 16, Number 2, 2003 191 The International Journal of Prosthodontics Provisional Crowns with SF2-Containing Temporary Cement Lewinstein et al

120 8 Pure 7 Pure 100 SnF2 P < .05 SnF 6 2 P < .001 80 5 P < .001 P < .01 4 P < .01 60 NS 3

40 Solubility (%)

Retentive force (N) 2 20 1

0 0 Tempbond Tempbond NE Freegenol Tempbond Tempbond NE Freegenol Cement type Cement type

Fig 2 Mean retentive force of crowns cemented with and with- Fig 3 Mean solubility of cements with and without SnF2. out SnF2. NS = nonsignificant.

Tempond showed significantly higher dye pene- Freegenol after 1 hour.8 In the present study, Freegenol

tration than Freegenol (P < .05). The differences be- with SnF2 had the highest retentive value. The differ- tween Tempbond and Tempbond NE, and between ences in the results of the present study and those of Tempbond NE and Freegenol, were not statistically other researchers may be attributed to different testing significant (P > .05). The addition of SnF2 did not sig- conditions and the time elapsing before testing. In the nificantly affect the dye penetration. present study, the cemented crowns were thermocy- There were no significant differences in solubility cled and tested 6 days later. These test conditions are of the different cements. However, the incorporation more relevant to simulation of long-term provisional of SnF2 significantly increased the solubility of all cementation. three cements (Freegenol and Tempbond NE, P < The incorporation of SnF2 nearly tripled the reten- .001; Tempbond, P < .01) (Fig 3). Freegenol with SnF2 tive strength of Tempbond NE, the weakest of the ce- showed the highest solubility and differed signifi- ments, and significantly improved the strength of

cantly from Tempbond with SnF2 (P < .001). With the Freegenol but not Tempbond. Since the first cements addition of SnF2, the solubility of Tempbond NE did are acid-base-oxide cements, it might be that SnF2 re- not differ from that of Tempbond or Freegenol. acts with the noneugenol cements to create a stronger structure, with no effect on the eugenol type of cement. Discussion In vitro microleakage studies with low–molecular weight dyes or isotopes are more severe than those

In this study, the incorporation of SnF2 to three tem- carried out in the mouth or with clinically relevant porary cements increased the retention and solubility macromolecular materials such as lipopolysaccha- but did not affect the microleakage. Without the ad- rides.12 Therefore, if a cement resists dye penetration dition of SnF2, the retentive force of Tempbond NE was in vitro, it is likely to perform even better clinically. significantly lower than that of the other two tempo- In our study, the dye penetrations of Tempbond and rary cements. No statistically significant difference in Tempbond NE were similar, while Freegenol was the retentive strength was found between Freegenol and most resistant. This may be attributed to Freegenol Tempbond. This is in accordance with a study that being more stable under thermocycling. Another found no statistically significant difference between study13 found that the leakage of crowns cemented Tempbond and Freegenol 24 hours after cementation with Tempbond NE is higher than that of those ce- of base-metal crowns.11 However, others1 found no mented with Tempbond, but this may be attributed significant difference after 24 hours in the retention of to different testing methods. In both studies, the me- provisional crowns cemented with Tempbond and dian values of the microleakage tests were relatively Tempbond NE. Another study8 has shown that tem- high, with different degrees of dye penetration in the porary crowns cemented with Tempbond are 2.5 times tested temporary cements. Our results indicate that

more retentive than those cemented with Freegenol 1 the addition of 0.4% SnF2 did not significantly alter hour after cementation. Also, the addition of Duraphat the dye penetration. fluoride varnish to the cements showed an increase in There is no American standard for temporary retentive strength with Tempbond and a decrease with dental cement. The American Dental Association’s

The International Journal of Prosthodontics 192 Volume 16, Number 2, 2003 Lewinstein et al Provisional Crowns with SF2-Containing Temporary Cement

(ADA) specification No. 3014 for solubility and dis- References integration of ZOE cements is less than 2.5% after 24 hours. Although the sample diameters and time 1. Lepe X, Bales DJ, Johnson GH. Retention of provisional crowns interval were different from the aforementioned fabricated from two materials with use of four temporary cements J Prosthet Dent 1999;81:469–475. specification, the solubility of tested temporary ce- 2. Donly KJ. Enamel and dentin demineralization inhibition of flu- ments in distilled water in our study was 0.6% to oride releasing materials. Am Dent J 1994;7:275–278. 0.7% after 30 days. Following the addition of SnF2, 3. ten Cate JM, van Duinen RN. Hypermineralization of dentinal the solubility and disintegration of Tempbond in- lesions adjacent to glass ionomer cement restorations. J Dent Res creased fourfold, Tempbond NE increased sixfold, 1995;74:1266–1267. 4. Garcia-Godoy F, Jensen ME. Artificial recurrent caries in glass and Freegenol increased sevenfold. However, the ionomer-lined amalgam restorations. Am J Dent 1990;3:83–89. solubility was below the ADA specification for ZOE 5. Tantbirojn D, Douglas WH, Versluis A. Inhibitive effect of a resin cements even though the specimens were immersed modified glass ionomer cement on remote enamel artificial for 30 days. Since fluoride salts are very soluble in caries. Caries Res 1997;31:275–280. water, it might be that the addition of SnF creates 6. Segura A, Donly KJ, Stratman RG. Enamel remineralization on 2 teeth adjacent to Class II glass ionomer restorations. Am J Dent a more soluble cement. Tempbond with SnF2 1997;10:247–250. showed relatively low solubility (2.1% after 30 7. Swartz ML, Phillips RW, Norman RD. Effect of fluoride-con- days). An increase in solubility of the cement may taining zinc oxide-eugenol cements on solubility of enamel. J improve its antibacterial properties by releasing flu- Dent Res 1970;49:576–580. oride, thereby reducing the demineralization of the 8. Lewinstein I, Daniel Z, Azaz B, Gedalia I. Effect of fluoride var- 15,16 nish on the retentive strength of provisional crowns luted with tooth substance. various temporary cements. J Prosthet Dent 1992;68:733–736. Tests in vitro cannot accurately reproduce clinical 9. Lewinstein I, Fuhrer N, Ganor Y. Effect of a fluoride varnish on factors such as oral temperature changes, occlusal the margin leakage and retention of luted provisional crowns. J forces, saliva of varying pH, buffer capacity and flow Prosthet Dent (forthcoming). rate, abrasion resistance of the cement,17 and the 10. Grajower R, Lewinstein I, Zeltser C. The effective minimum ce- ment thickness of zinc phosphate cement for luted-non precious acid environment produced by bacteria such as crowns. J Oral Rehabil 1985;12:234–245. Streptococcus mutans and lactobacilli, which may af- 11. Olin PS, Rudney JD, Hill EME. Retentive strength of six tempo- fect the degradation of the cement.12 Cement disso- rary dental cements. Quintessence Int 1990;21:197–200. lution may be minimized by accurately fitting restora- 12. Coleman AJ, Moses MS, Rickerby HHD. Macromolecular leak- tions. Microgaps at the margins of restorations expose age beneath full cast crowns: A two-year in vitro investigation. J Prosthet Dent 2001;85:20–25. the cement to the oral fluids, resulting in cement dis- 13. Baldissara P, Comin G, Martone F, Scotti R. Comparative study solution and marginal leakage. Marginal openings of of the marginal microleakage of six cements in fixed provisional 150 µm showed significantly increased solubility of crowns. J Prosthet Dent 1998;80:417–422. zinc-phosphate cement compared to smaller open- 14. American Dental Association, Council on Dental Materials and ings.18 It has been shown that careful selection of the Devices. New American Dental Association specification No. 30 for dental zinc oxide-eugenol type restorative materials. J Am acrylic resin and relining can reduce the marginal gap Dent Assoc 1977;95:991–995. 19 in provisional crowns. Further studies on the opti- 15. Mesu FP, Reedijk T. Degradation of luting cements measured in mal SnF2:cement ratios with regard to physical prop- vitro and in vivo. J Dent Res 1983;62:1236–1240. erties and long-term antibacterial effects are required. 16. Mirth DB, Adderly DD, Amsbaugh SM, Monel-Torens E, Li SH, The addition of SnF increased the retention of Bowen WH. Inhibition of experimental caries using an intrao- 2 ral fluoride-releasing device. J Am Dent Assoc 1983;107:55–58. temporary crowns cemented with Tempbond NE and 17. Norman RD, Swartz ML, Phillips RW, Virmani R. A comparison Freegenol but did not affect the retention of those ce- of intraoral disintegration of three dental cements. J Am Dent Assoc mented with Tempbond. The marginal leakage of 1961;78:772–782. temporary crowns cemented with the tested tempo- 18. Jacobs MS, Windeler AS. An investigation of dental luting ce- rary cements with and without the addition of SnF ment solubility as a function of the marginal gap. J Prosthet Dent 2 1991;65:436–442. was similar. However, incorporation of SnF2 in- 19. Ehrenberg DS, Weiner S. Changes in marginal gap size of pro- creased the solubility of the cements. visional resin crowns after occlusal loading and thermal cycling. J Prosthet Dent 2000;84:139–148.

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