Polymerization time compatibility index of polyvinyl siloxane impression materials with conventional and experimental gingival margin displacement agents Danuta Nowakowska, PhD,a Zbigniew Raszewski, PhD,b Jolanta Saczko, PhD,c Julita Kulbacka, PhD,d and Wlodzimierz Wie˛ckiewicz, PhDe Wroclaw Medical University, Poland Statement of problem. No consensus exists as to the compatibility of chemical agents used with gingival displacement methods with different impression materials. Purpose. The aim of this study was to investigate the effect of conventional and experimental gingival displacement agents on the polymerization time of polyvinyl siloxane impression elastomers. Material and methods. The study comprised 10 gingival displacement agents, including 5 conventional astringents (10%, 20%, and 25% aluminum chloride, 25% aluminum sulfate, and 15.5% ferric sulfate) and 5 experimental adrenergics (0.1% and 0.01% HCl-epinephrine, 0.05% HCl-tetrahydrozoline, 0.05% HCl-oxymetazoline, and 10% HCl-phenylephrine). The polymerization time of 240 specimens (weight 3.3 g) of 4 polyvinyl siloxane (PVS) impression elastomers, type 3 (Colorise Thermochromic, Hydrorise, Express, and Take 1 Advanced), after mixing with 20 mL of each displacement agent, was measured with a viscometer. The 24 specimens from the control group were polymerized without contact with the displacement agents. The studies were performed at 23 C and 37 C (0.1 C). Results. A polymerization time compatibility index (PTCI) was devised, where the polymerization time of PVS mixed with the displacement agents was expressed as the percentage of the standard polymerization time of the impression material. The PTCI values at 23 C were higher than those at 37 C for both groups of displacement agents. At 37 C, the experimental displacement agents achieved higher PTCI values than the conventional agents. Conclusions. All of the evaluated displacement agents at laboratory and intraoral temperatures induced changes in the polymerization time of PVS. Therefore, chemical displacement agents should not come into direct contact with PVS impression materials. (J Prosthet Dent 2014;-:---)
Clinical Implications Chemical agents used in gingival displacement methods at laboratory and intraoral temperatures can induce changes in the polymerization time of polyvinyl siloxane (PVS). The proposed polymerization time compatibility index for impression elastomers is expressed as a comparison of standard polymerization time and setting time after contact with a displacement agent. In a clinical situation, this index can facilitate decisions concerning the choice of displacement agent before the impression procedure with PVS. Compatible dental materials are essential for the precise fitting of fixed prosthodontic restorations. Temporary displacement of the free gingival tissue a
precedes several procedures, including impression making. The chemomechanical method with displacement materials and chemical agents is the most
frequently selected.1-3 Gingival displacement agents belong to different chemical and pharmacological action groups.4,5 They can be divided into 2 classes,
Assistant Professor and Chair, Department of Dental Materials, Wroclaw Medical University. Zhermapol, Dental Materials, Warsaw, Poland. c Professor, Department of Medical Biochemistry, Wroclaw Medical University. d Assistant Professor, Department of Medical Biochemistry, Wroclaw Medical University. e Professor, Department of Prosthodontics, Wroclaw Medical University. b
Nowakowska et al
2
Volume conventional displacement agents (CDAs) and experimental displacement agents (EDAs). CDAs cause hemostatic and tissue protein precipitation and consequently tissue contraction. EDAs are vasoconstrictors, which provide effective vasoconstriction and hemostasis in the microcapillary system of the free gingival margin.4-7 CDAs contain inorganic metal salts, aluminum chloride, aluminum sulfate, or ferric sulfate in various concentrations. Vasoconstrictive agents contain different organic salts of hydrochloric acid, which activate a- and b-receptors (a- and b-adrenergics) or only a-receptors (a-adrenergics). From the a- and badrenergics group, 0.1% HCl-epinephrine is most commonly used, although Fazekas et al8 and Csillag et al9 reported that lower concentrations (0.01%) were equally effective as displacement agents. Bowles et al10 proposed the synthetic sympathomimetic amine group of aadrenergics (0.05% HCl-tetrahydrozoline, 0.05% HCl-oxymetazoline, and 0.25% HCl-phenylephrine) as more effective and safer displacement agents. These chemical gingival displacement agents are manufactured in different forms: liquids for soaking or preimpregnated gingival displacement cords and injection-type gels and pastes. Under clinical conditions, all these materials and chemical displacement agents are placed directly into the gingival sulcus for the time required to obtain effective displacement (average from 3 to 10 minutes).11 Immediately before making an impression, they are removed, and the gingival sulcus is rinsed with an air/water spray. However, chemical residues often remain inside the gingival space, and there they come into contact with impression material during polymerization. Additionally, in the double-cord displacement procedure, the thinner nonimpregnated cord placed in the apical extent of the gingival sulcus often gets soaked by contact with thicker impregnated cord during the primary phase of the 2-step putty/wash impression technique.12 After the impression procedure, the gingival sulcus quickly recloses, and the remains of
the chemical displacement agents are washed away and neutralized by gingival fluid and saliva.13,14 The compatibility of CDAs with different elastomer impression materials has not been completely evaluated. Earlier observations of polyvinyl siloxane (PVS) polymerization suggested that its inhibition results from sulfur originating from latex materials such as latex gloves and dental dams or indirectly from sulfur contaminated displacement cords.15-23 Kimoto et al19 reported that latex gloves in contact with displacement cords prolonged the polymerization time of PVS despite cleaning the gloves with water, detergents, or alcohol. An attempt was made to overcome these difficulties by using vinyl or nitrile gloves.22 Bauman15 presumed that PVS polymerization inhibition may be caused by a different compound originating from natural latex gum (zinc diethyl dithiocarbamate). Other studies reported that synthetic latex did not affect PVS polymerization. The introduction of static and dynamic mixing systems for components of impression elastomers with different density eliminated this problem.24 The effects of CDAs on the polymerization of 5 impression elastomer groups-polysulfides (PS), condensation silicones (CS), polyvinyl siloxanes (PVS), polyethers (PE), and the newly introduced hybrid material vinylsiloxanether (VSXE)-have been examined.25-29 25 O’Mahony et al found that ferric subsulfate, ferric sulfate, and aluminum chloride interfere with the quality of detail reproduction by PVS impression, possibly because of the sulfur that delays or inhibits polymerization. Nowakowska et al26 documented the inhibition of the polymerization time of 3 PEs after contact with the sulfur contained in a conventional displacement chemical, 15.5% ferric sulfate solution (Astringedent; Ultradent Products Inc), but observed no such effect with 10% aluminum chloride (Gingiva Liquid; Roeko), 25% aluminum chloride (Racestyptine solution; Septodont), or 15.5% ferric sulfate (Astringedent; Ultradent Products Inc) on 3 PVS and 3 CS. Sábio et al27 assessed
The Journal of Prosthetic Dentistry
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Issue
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the effect of 3 gingival displacement solutions, conventional aluminium chloride (Hemostop; Dentsply Ind.- e Com.- Ltda) and 2 experimental a-adrenergics, tetrahydrozoline hydrochloride (Vislin; Alcon Laboratórios do Brazil Ltda) and oxymetazoline hydrochloride (Afrin; Schering-Plough Productos Farmacêuticos), on the tensile strength and inhibition of the polymerization of 4 types of impression materials: PS, CS, PVS, and PE. In this study, the tensile strength of PS impressions decreased after contact with aluminum chloride and oxymetazoline hydrochloride, which suggests that these chemicals interfere with the polymerization setting. However, none of the chemical solutions prolonged the polymerization time of PS not affected the tensile strength of CS, whereas aluminum chloride inhibited CS polymerization. PE presented lower tensile strength after polymerization in contact with aluminum chloride and both evaluated a-adrenergics. PE polymerization was inhibited only by Hemostop (Dentsply Ind. e Com. Ltda). The PVS specimens polymerized in contact with aluminum chloride had significantly lower tensile strength, whereas the 2 assessed experimental medicaments did not affect the tensile strength of PVS or CS. The results of this study showed that only the experimental medicament Vislin (Alcon Laboratórios do Brazil Ltda) can be used as a gingival displacement agent without affecting the tested properties of the 4 impression materials. Machado and Guedes28 analyzed polymerization inhibition by observing PVS impressions and the molded surface texture and concluded that conventional hemostatic solutions such as aluminum sulfate (Gel Cord; Pascal Intl), ferric sulfate (StatGel FS; Pascal Intl), and aluminum chloride (Hemostop; Dentsply Caulk) did not show any inhibitory potential on the addition silicone. The effects of CDAs and EDAs on PVS are unclear, possibly because different materials and methods were used in all 4 of the previously mentioned studies. In all of the evaluations
Nowakowska et al
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2014
of different displacement agents on the polymerization reaction kinetics of various impression elastomers, the experiments were conducted at laboratory temperature. Berg et al30 reported that the rheological properties of PVS and PE impression materials depended significantly on the temperature at which the polymerization process occurred, as temperature may affect material properties and setting kinetics. Nowakowska and Raszewski29 evaluated the effect of CDAs and EDAs on vinylsiloxanether (Identium Light; Kettenbach) at 23 C and 37 C and found that at the intraoral temperature CDAs exhibited higher compatibility with VSXE than at the laboratory temperature. In contrast, for EDAs, the compatibility was comparably high at both temperatures. The purpose of this study was to evaluate the effect of CDAs and EDAs on the polymerization time of 4 PVS impression elastomers at laboratory and intraoral temperatures. The study tested the null hypothesis that none of the chemical displacement agents from either group changed the polymerization time of PVS.
MATERIAL AND METHODS In the current study, 10 commonly used chemical displacement agents were selected: 5 CDAs (astringents) and 5 EDAs (adrenergics). The CDA group included 3 aluminum chlorides10% Gingiva Liquid, 20% Alustin, 25% Racestyptine solution-as well as aluminum sulfate 25% Orbat sensitive, and ferric sulfate 15.5% Astringedent. The EDA group included 2 a- and b-adrenergics-0.1% HCl-epinephrine Injec. Adrenalini, and a 10 distilled water dilution of 0.01% HCl-epinephrine-as well as 3 a-adrenergics: 0.05% HCltetrahydrozoline Visine classic, 0.05% HCl-oxymetazoline Afrin, and 10% HClphenylephrine Neosynephrin POS 10%. The manufacturers and characteristics of the evaluated chemical displacement agents are shown in Table I. The effects of these agents on the polymerization time of 4 PVS type-3
Nowakowska et al
3
Table I.
Characteristics of evaluated gingival margin displacement agents
Group
Displacement Agent
Manufacturer
CRA
Gingiva liquid
Roeko, Coltène/Whaledent
10% aluminum chloride
Alustin
Chema-Elektromet
20% aluminum chloride
Racestyptine solution
Septodont
25% aluminum chloride
Orbat sensitive
Lege Artis; Pharma GmbH þ Co KG
25% aluminum sulfate
Ultradent Products Inc
15.5% ferric sulfate
Astringedent ERA
Injec. Adrenalini 0.1%
Active Ingredient
Warszawskie Zakłady Farmaceutyczne Polfa S.A.
0.1% HCl-epinephrine
Injec. Adrenalini 0.01%
Self-made 10x diluton of Injec. Adrenalini 0.1% Warszawskie Zakłady Farmaceutyczne Polfa S.A.
0.01% HCL-epinephrine
Visine classic
Heinrich Mack Nachf. GmbH & Co.KG
Afrin
Schering-Plough Labo N.V.
NeosynephrinPOS 10%
Ursapharm, Arzneimittel GmbH& Co. KG
0.05% HCl-tetrahydrozoline 0.05% HCL-oxymetazoline 10% HCL-phenylephrine
CRA, conventional displacement agents; ERA, experimental displacement agents.
(Colorise Thermochromic light body; and Hydrorise light body; Zhermack Spa, Express light body; 3M ESPE, and Take 1 Advanced light body wash; Kerr Corp) were evaluated by using the rheological method. For this study, 120 VPS specimens of 3.3 g in weight were mixed with 20 mL each of evaluated displacement agents by a Labs CAP 2000þ viscometer (Brookfield Engineering Laboratories). Polymerization time was measured in seconds until the impression material was entirely polymerized (shear forces). The total specimen size was 264 (132 in each temperature condition), including 24 control specimens. The impression materials increased in viscosity until the highest point on the viscosity curve expressed in centipoises [cP] was reached. The time taken to achieve this point was recorded as the elastomer’s polymerization time. The control group specimens, 3 from each impression PVS, were polymerized without contact with the displacement agents. Three series of experiments were performed at laboratory and intraoral temperature: 23 C and 37 C (0.1 C).
Descriptive statistics are presented as mean (SD) values. The significance of the difference between the mean values of different groups of gingival displacement agents was assessed with a t test with a P value of P
Clinical Implications Chemical agents used in gingival displacement methods at laboratory and intraoral temperatures can induce changes in the polymerization time of polyvinyl siloxane (PVS). The proposed polymerization time compatibility index for impression elastomers is expressed as a comparison of standard polymerization time and setting time after contact with a displacement agent. In a clinical situation, this index can facilitate decisions concerning the choice of displacement agent before the impression procedure with PVS. Compatible dental materials are essential for the precise fitting of fixed prosthodontic restorations. Temporary displacement of the free gingival tissue a
precedes several procedures, including impression making. The chemomechanical method with displacement materials and chemical agents is the most
frequently selected.1-3 Gingival displacement agents belong to different chemical and pharmacological action groups.4,5 They can be divided into 2 classes,
Assistant Professor and Chair, Department of Dental Materials, Wroclaw Medical University. Zhermapol, Dental Materials, Warsaw, Poland. c Professor, Department of Medical Biochemistry, Wroclaw Medical University. d Assistant Professor, Department of Medical Biochemistry, Wroclaw Medical University. e Professor, Department of Prosthodontics, Wroclaw Medical University. b
Nowakowska et al
2
Volume conventional displacement agents (CDAs) and experimental displacement agents (EDAs). CDAs cause hemostatic and tissue protein precipitation and consequently tissue contraction. EDAs are vasoconstrictors, which provide effective vasoconstriction and hemostasis in the microcapillary system of the free gingival margin.4-7 CDAs contain inorganic metal salts, aluminum chloride, aluminum sulfate, or ferric sulfate in various concentrations. Vasoconstrictive agents contain different organic salts of hydrochloric acid, which activate a- and b-receptors (a- and b-adrenergics) or only a-receptors (a-adrenergics). From the a- and badrenergics group, 0.1% HCl-epinephrine is most commonly used, although Fazekas et al8 and Csillag et al9 reported that lower concentrations (0.01%) were equally effective as displacement agents. Bowles et al10 proposed the synthetic sympathomimetic amine group of aadrenergics (0.05% HCl-tetrahydrozoline, 0.05% HCl-oxymetazoline, and 0.25% HCl-phenylephrine) as more effective and safer displacement agents. These chemical gingival displacement agents are manufactured in different forms: liquids for soaking or preimpregnated gingival displacement cords and injection-type gels and pastes. Under clinical conditions, all these materials and chemical displacement agents are placed directly into the gingival sulcus for the time required to obtain effective displacement (average from 3 to 10 minutes).11 Immediately before making an impression, they are removed, and the gingival sulcus is rinsed with an air/water spray. However, chemical residues often remain inside the gingival space, and there they come into contact with impression material during polymerization. Additionally, in the double-cord displacement procedure, the thinner nonimpregnated cord placed in the apical extent of the gingival sulcus often gets soaked by contact with thicker impregnated cord during the primary phase of the 2-step putty/wash impression technique.12 After the impression procedure, the gingival sulcus quickly recloses, and the remains of
the chemical displacement agents are washed away and neutralized by gingival fluid and saliva.13,14 The compatibility of CDAs with different elastomer impression materials has not been completely evaluated. Earlier observations of polyvinyl siloxane (PVS) polymerization suggested that its inhibition results from sulfur originating from latex materials such as latex gloves and dental dams or indirectly from sulfur contaminated displacement cords.15-23 Kimoto et al19 reported that latex gloves in contact with displacement cords prolonged the polymerization time of PVS despite cleaning the gloves with water, detergents, or alcohol. An attempt was made to overcome these difficulties by using vinyl or nitrile gloves.22 Bauman15 presumed that PVS polymerization inhibition may be caused by a different compound originating from natural latex gum (zinc diethyl dithiocarbamate). Other studies reported that synthetic latex did not affect PVS polymerization. The introduction of static and dynamic mixing systems for components of impression elastomers with different density eliminated this problem.24 The effects of CDAs on the polymerization of 5 impression elastomer groups-polysulfides (PS), condensation silicones (CS), polyvinyl siloxanes (PVS), polyethers (PE), and the newly introduced hybrid material vinylsiloxanether (VSXE)-have been examined.25-29 25 O’Mahony et al found that ferric subsulfate, ferric sulfate, and aluminum chloride interfere with the quality of detail reproduction by PVS impression, possibly because of the sulfur that delays or inhibits polymerization. Nowakowska et al26 documented the inhibition of the polymerization time of 3 PEs after contact with the sulfur contained in a conventional displacement chemical, 15.5% ferric sulfate solution (Astringedent; Ultradent Products Inc), but observed no such effect with 10% aluminum chloride (Gingiva Liquid; Roeko), 25% aluminum chloride (Racestyptine solution; Septodont), or 15.5% ferric sulfate (Astringedent; Ultradent Products Inc) on 3 PVS and 3 CS. Sábio et al27 assessed
The Journal of Prosthetic Dentistry
-
Issue
-
the effect of 3 gingival displacement solutions, conventional aluminium chloride (Hemostop; Dentsply Ind.- e Com.- Ltda) and 2 experimental a-adrenergics, tetrahydrozoline hydrochloride (Vislin; Alcon Laboratórios do Brazil Ltda) and oxymetazoline hydrochloride (Afrin; Schering-Plough Productos Farmacêuticos), on the tensile strength and inhibition of the polymerization of 4 types of impression materials: PS, CS, PVS, and PE. In this study, the tensile strength of PS impressions decreased after contact with aluminum chloride and oxymetazoline hydrochloride, which suggests that these chemicals interfere with the polymerization setting. However, none of the chemical solutions prolonged the polymerization time of PS not affected the tensile strength of CS, whereas aluminum chloride inhibited CS polymerization. PE presented lower tensile strength after polymerization in contact with aluminum chloride and both evaluated a-adrenergics. PE polymerization was inhibited only by Hemostop (Dentsply Ind. e Com. Ltda). The PVS specimens polymerized in contact with aluminum chloride had significantly lower tensile strength, whereas the 2 assessed experimental medicaments did not affect the tensile strength of PVS or CS. The results of this study showed that only the experimental medicament Vislin (Alcon Laboratórios do Brazil Ltda) can be used as a gingival displacement agent without affecting the tested properties of the 4 impression materials. Machado and Guedes28 analyzed polymerization inhibition by observing PVS impressions and the molded surface texture and concluded that conventional hemostatic solutions such as aluminum sulfate (Gel Cord; Pascal Intl), ferric sulfate (StatGel FS; Pascal Intl), and aluminum chloride (Hemostop; Dentsply Caulk) did not show any inhibitory potential on the addition silicone. The effects of CDAs and EDAs on PVS are unclear, possibly because different materials and methods were used in all 4 of the previously mentioned studies. In all of the evaluations
Nowakowska et al
-
2014
of different displacement agents on the polymerization reaction kinetics of various impression elastomers, the experiments were conducted at laboratory temperature. Berg et al30 reported that the rheological properties of PVS and PE impression materials depended significantly on the temperature at which the polymerization process occurred, as temperature may affect material properties and setting kinetics. Nowakowska and Raszewski29 evaluated the effect of CDAs and EDAs on vinylsiloxanether (Identium Light; Kettenbach) at 23 C and 37 C and found that at the intraoral temperature CDAs exhibited higher compatibility with VSXE than at the laboratory temperature. In contrast, for EDAs, the compatibility was comparably high at both temperatures. The purpose of this study was to evaluate the effect of CDAs and EDAs on the polymerization time of 4 PVS impression elastomers at laboratory and intraoral temperatures. The study tested the null hypothesis that none of the chemical displacement agents from either group changed the polymerization time of PVS.
MATERIAL AND METHODS In the current study, 10 commonly used chemical displacement agents were selected: 5 CDAs (astringents) and 5 EDAs (adrenergics). The CDA group included 3 aluminum chlorides10% Gingiva Liquid, 20% Alustin, 25% Racestyptine solution-as well as aluminum sulfate 25% Orbat sensitive, and ferric sulfate 15.5% Astringedent. The EDA group included 2 a- and b-adrenergics-0.1% HCl-epinephrine Injec. Adrenalini, and a 10 distilled water dilution of 0.01% HCl-epinephrine-as well as 3 a-adrenergics: 0.05% HCltetrahydrozoline Visine classic, 0.05% HCl-oxymetazoline Afrin, and 10% HClphenylephrine Neosynephrin POS 10%. The manufacturers and characteristics of the evaluated chemical displacement agents are shown in Table I. The effects of these agents on the polymerization time of 4 PVS type-3
Nowakowska et al
3
Table I.
Characteristics of evaluated gingival margin displacement agents
Group
Displacement Agent
Manufacturer
CRA
Gingiva liquid
Roeko, Coltène/Whaledent
10% aluminum chloride
Alustin
Chema-Elektromet
20% aluminum chloride
Racestyptine solution
Septodont
25% aluminum chloride
Orbat sensitive
Lege Artis; Pharma GmbH þ Co KG
25% aluminum sulfate
Ultradent Products Inc
15.5% ferric sulfate
Astringedent ERA
Injec. Adrenalini 0.1%
Active Ingredient
Warszawskie Zakłady Farmaceutyczne Polfa S.A.
0.1% HCl-epinephrine
Injec. Adrenalini 0.01%
Self-made 10x diluton of Injec. Adrenalini 0.1% Warszawskie Zakłady Farmaceutyczne Polfa S.A.
0.01% HCL-epinephrine
Visine classic
Heinrich Mack Nachf. GmbH & Co.KG
Afrin
Schering-Plough Labo N.V.
NeosynephrinPOS 10%
Ursapharm, Arzneimittel GmbH& Co. KG
0.05% HCl-tetrahydrozoline 0.05% HCL-oxymetazoline 10% HCL-phenylephrine
CRA, conventional displacement agents; ERA, experimental displacement agents.
(Colorise Thermochromic light body; and Hydrorise light body; Zhermack Spa, Express light body; 3M ESPE, and Take 1 Advanced light body wash; Kerr Corp) were evaluated by using the rheological method. For this study, 120 VPS specimens of 3.3 g in weight were mixed with 20 mL each of evaluated displacement agents by a Labs CAP 2000þ viscometer (Brookfield Engineering Laboratories). Polymerization time was measured in seconds until the impression material was entirely polymerized (shear forces). The total specimen size was 264 (132 in each temperature condition), including 24 control specimens. The impression materials increased in viscosity until the highest point on the viscosity curve expressed in centipoises [cP] was reached. The time taken to achieve this point was recorded as the elastomer’s polymerization time. The control group specimens, 3 from each impression PVS, were polymerized without contact with the displacement agents. Three series of experiments were performed at laboratory and intraoral temperature: 23 C and 37 C (0.1 C).
Descriptive statistics are presented as mean (SD) values. The significance of the difference between the mean values of different groups of gingival displacement agents was assessed with a t test with a P value of P
