Comparison of pressure generated by cordless gingival displacement materials Vincent Bennani, DDS, PhD,a Melissa Inger, BSc,b and John M. Aarts, MHealScc Faculty of Dentistry, University of Otago, New Zealand Statement of problem. Because pressure generated by a displacement cord may traumatize the gingiva, cordless gingival displacement materials are available to the clinician as atraumatic alternatives. However, whether the pressures produced by the different systems are equivalent is unclear. Purpose. The purpose of this study was to investigate the pressures generated by 4 different cordless gingival displacement materials. Material and methods. A chamber with a dimension of 5 5 2 mm was made from Type IV stone and silicone material to simulate a rigid and elastic environment. A pressure gauge was embedded into the wall of the chamber, and 4 materials (Expasyl, Expasyl New, 3M ESPE Astringent Retraction Paste, and Magic FoamCord) were injected into the chamber. The maximum and postinjection pressures were recorded with Chart 5 software and the Power Lab system. The pressures generated by the different materials were compared with a post hoc Mann-Whitney U test (a¼.05). Results. The median postinjection pressures generated by Expasyl (142.2 kPa) and Expasyl New (127.6 kPa) were significantly greater than the pressures generated by 3M ESPE Astringent Retraction Paste (58.8 kPa) and Magic Foam Cord (32.8 kPa). Expasyl generated a maximum pressure of 317.4 kPa and Expasyl New of 296.6 kPa during injection, whereas 3M ESPE Astringent Retraction Paste generated 111.0 kPa, and Magic Foam Cord generated 17.8 kPa. Conclusions. All cordless systems produced atraumatic pressures, with Expasyl New and Expasyl generating the highest pressures and, therefore, can be considered the most effective material. (J Prosthet Dent 2014;-:---)
Clinical Implications All of the paste systems tested produced lower pressure than those reported for displacement cord, which makes it less likely that they would traumatize the gingival tissue. However, the pressure generated by cordless systems is more than 10 times less than with displacement cord, and this could result in inadequate displacement. Expasyl and Expasyl New generated significantly greater pressure than 3M ESPE Astringent Retraction Paste and Magic FoamCord. However, to select the appropriate displacement paste material for tissue displacement, further research is required to determine the effectiveness of the different cordless systems. When making impressions of subgingival crown margins or restoring cervical lesions, the clinician must often displace the gingiva to gain access to the prepared margin. The technique used should be atraumatic to a
the periodontal tissues.1-4 Methods for displacing the gingiva include mechanical, chemomechanical (chemicals embedded in cords or in an injectable matrix), and surgical (lasers, electrosurgery, and rotary curettage).5
Senior Lecturer, Department of Oral Rehabilitation. Graduate student, School of Dentistry. c Senior Teaching Fellow, Department of Oral Rehabilitation. b
Bennani et al
Whichever method is used, ideal gingival displacement should ensure the health of the epithelial attachment. This health is compromised when the pressure generated by the gingival displacement method is greater than
2
Volume what the epithelial attachment can withstand. Van der Velden6 recommended an effective probing force of 0.75 N to allow the probe tip to reach the bottom of the sulcus while maintaining an intact coronal connective tissue. Based on a 0.63-mm-diameter probe, it will generates a pressure of 2400 kPa. Conventional displacement cords are physically placed into the crevicular sulcus by the clinician. This is problematic because the pressure generated by placing cords can reach up to 5000 kPa.1 Excessive force can induce bleeding and cause acute injury, which may take more than 1 week to heal.7,8 This potential for trauma has encouraged the use of cordless displacement systems. Investigation into these methods has shown that significantly less pressure is generated than with displacement cord,1 which is likely due to the nature of placement and physical properties of the materials. The cordless systems available are a paste or foam that is injected into the crevicular sulcus. This removes the need for the clinician to physically compress the material into the cervicular sulcus, where it may generate very high pressures and cause injury. Because of their advantages over conventional cord systems, different cordless gingival displacement systems have been developed.9,10 This study investigated the pressure generated by 4 different cordless gingival displacement materials. The null hypothesis was that different cordless gingival displacement materials would not generate different pressures.
MATERIAL AND METHODS A 5 5 2-mm chamber was made from silicone (Deguform; DeguDent) on 4 of the 5 surfaces to simulate a crevicular space. The fifth surface was Type IV stone (GC Fujirock EP; GC Europe N.V.) (Fig. 1). The silicone material used has a Shore hardness A value of 14 to 16, which is similar to human soft tissue (Shore hardness A value 16-21).11 A full bridge active pressure gauge (Model-105S; Precision
Pressure gauge
-
Issue
-
5 x 2 mm opening
Chamber Stone
Silicone
1 Test chamber with pressure gauge. Measurement Company) was embedded into the stone surface. Four materials were tested: Expasyl (Acteon), Expasyl New (Acteon), 3M ESPE Astringent Retraction Paste ARP (3M ESPE), and Magic FoamCord (Coltène/ Whaledent). All 4 of the materials were applied according to the manufacturer’s instructions. Expasyl is a kaolinbased material with 15% aluminum chloride and water. Expasyl New is an oats-based material with 15% aluminum chloride and water. Expasyl New is a new product not yet commercially available. The 3M ESPE ARP paste is made of kaolin material, 15% aluminum chloride, water, mica group minerals, and polydimethylsiloxane. Magic FoamCord is a polyvinyl siloxane elastomer. Expasyl and Expasyl New were injected into the chamber with an Expasyl Power applicator motorized gun with a 1.5-mm-diameter injection tip at 20 000 rpm. The 3M ESPE ARP paste was injected into the chamber with a manual applicator handheld gun with a 1-mm-diameter injection tip supplied by 3M ESPE. Magic FoamCord was injected into the chamber with a handheld applicator with a 1.5mm-diameter injection tip supplied by Coltène/Whaledent. The pressure was recorded 1000 times per second with a recording system (Powerlab, AD Instruments) with the software Chart, version 5 (AD Instruments). Before each series of tests, or if the testing was interrupted, the pressure gauge was calibrated by placing it into a pressure chamber where a known pressure could be applied. After each test, the silicone
The Journal of Prosthetic Dentistry
and stone compartments were separated and the material was removed. If material residue remained within the chamber space, or if any residue remained on the gauge, it was carefully removed with a microbrush (Microbrush) and orange solvent (Orange Solvent; Dux Dental). A clean microbrush was then used to remove all residues, and the area was dried. Every attempt was made to optimize the delivery of the displacement material; this included the use of new capsules and tips for every test and constant delivery of the material. The gun applicator and injection tip recommended by the manufacturer was used for each of the materials. The gun applicator tip was placed at the base and parallel to the long axis of the chamber for each test. All of the materials were injected into the chamber until the space was overfilled and then the tip of the applicator was slowly retracted while injection continued. All of the tests were performed by 1 operator (M.I.). Each group was tested 15 times, and the median maximum injection pressure (kPa) and median postinjection pressure (kPa) were calculated. The postinjection pressure was determined by averaging the median pressure values from the point at which the applicator was withdrawn to 1 minute after withdrawal. The pressure did not fluctuate and was static after 1 minute. Because of abnormal distribution, the data were analyzed with a KruskalWallis test. A post hoc analysis was then performed with pairwise Mann-Whitney U tests. A Bonferroni
Bennani et al
-
2014
Table I.
3 Injection and postinjection pressure values for Expasyl, Expasyl New, 3M ESPE ARP, and Magic FoamCord in kPa
Injection Pressure Materials Tested Minimum Maximum Median
Postinjection Pressure Interquartile Interquartile Range Minimum Maximum Median Range
Expasyl
144.2
317.4
181.5
67.2
110.4
180.8
142.2
40.9
Expasyl New
120.2
296.6
218.8
62.6
103.2
165.9
127.6
30.7
36.4
111.0
63.6
52.3
24.7
77.8
58.8
26.1
6.6
17.8
9.0
3.3
18.0
43.1
32.8
0.5
3M ESPE ARP Magic FoamCord
correction was then done, and the test was not considered statistically significant unless the P value was less than .05/6¼.0083. All statistical analyses were performed with statistical software (SPSS v19.0.0; SPSS Inc).
RESULTS The minimum, maximum, and median pressures during injection into the silicone chamber and the postinjection pressure values of the 4 different materials are shown in Table I. Expasyl, Expasyl New, and 3M ESPE ARP all had injection pressures greater than their respective postinjection pressures. Magic FoamCord was the only material that had a postinjection pressure greater than the injection pressure. Expasyl New and Expasyl generated the greatest injection pressures, followed by 3M ESPE ARP and then Magic FoamCord. Expasyl New and Expasyl also generated the greatest postinjection pressures, followed by 3M ESPE ARP and then Magic FoamCord. The Kruskal-Wallis test was significant (P
Clinical Implications All of the paste systems tested produced lower pressure than those reported for displacement cord, which makes it less likely that they would traumatize the gingival tissue. However, the pressure generated by cordless systems is more than 10 times less than with displacement cord, and this could result in inadequate displacement. Expasyl and Expasyl New generated significantly greater pressure than 3M ESPE Astringent Retraction Paste and Magic FoamCord. However, to select the appropriate displacement paste material for tissue displacement, further research is required to determine the effectiveness of the different cordless systems. When making impressions of subgingival crown margins or restoring cervical lesions, the clinician must often displace the gingiva to gain access to the prepared margin. The technique used should be atraumatic to a
the periodontal tissues.1-4 Methods for displacing the gingiva include mechanical, chemomechanical (chemicals embedded in cords or in an injectable matrix), and surgical (lasers, electrosurgery, and rotary curettage).5
Senior Lecturer, Department of Oral Rehabilitation. Graduate student, School of Dentistry. c Senior Teaching Fellow, Department of Oral Rehabilitation. b
Bennani et al
Whichever method is used, ideal gingival displacement should ensure the health of the epithelial attachment. This health is compromised when the pressure generated by the gingival displacement method is greater than
2
Volume what the epithelial attachment can withstand. Van der Velden6 recommended an effective probing force of 0.75 N to allow the probe tip to reach the bottom of the sulcus while maintaining an intact coronal connective tissue. Based on a 0.63-mm-diameter probe, it will generates a pressure of 2400 kPa. Conventional displacement cords are physically placed into the crevicular sulcus by the clinician. This is problematic because the pressure generated by placing cords can reach up to 5000 kPa.1 Excessive force can induce bleeding and cause acute injury, which may take more than 1 week to heal.7,8 This potential for trauma has encouraged the use of cordless displacement systems. Investigation into these methods has shown that significantly less pressure is generated than with displacement cord,1 which is likely due to the nature of placement and physical properties of the materials. The cordless systems available are a paste or foam that is injected into the crevicular sulcus. This removes the need for the clinician to physically compress the material into the cervicular sulcus, where it may generate very high pressures and cause injury. Because of their advantages over conventional cord systems, different cordless gingival displacement systems have been developed.9,10 This study investigated the pressure generated by 4 different cordless gingival displacement materials. The null hypothesis was that different cordless gingival displacement materials would not generate different pressures.
MATERIAL AND METHODS A 5 5 2-mm chamber was made from silicone (Deguform; DeguDent) on 4 of the 5 surfaces to simulate a crevicular space. The fifth surface was Type IV stone (GC Fujirock EP; GC Europe N.V.) (Fig. 1). The silicone material used has a Shore hardness A value of 14 to 16, which is similar to human soft tissue (Shore hardness A value 16-21).11 A full bridge active pressure gauge (Model-105S; Precision
Pressure gauge
-
Issue
-
5 x 2 mm opening
Chamber Stone
Silicone
1 Test chamber with pressure gauge. Measurement Company) was embedded into the stone surface. Four materials were tested: Expasyl (Acteon), Expasyl New (Acteon), 3M ESPE Astringent Retraction Paste ARP (3M ESPE), and Magic FoamCord (Coltène/ Whaledent). All 4 of the materials were applied according to the manufacturer’s instructions. Expasyl is a kaolinbased material with 15% aluminum chloride and water. Expasyl New is an oats-based material with 15% aluminum chloride and water. Expasyl New is a new product not yet commercially available. The 3M ESPE ARP paste is made of kaolin material, 15% aluminum chloride, water, mica group minerals, and polydimethylsiloxane. Magic FoamCord is a polyvinyl siloxane elastomer. Expasyl and Expasyl New were injected into the chamber with an Expasyl Power applicator motorized gun with a 1.5-mm-diameter injection tip at 20 000 rpm. The 3M ESPE ARP paste was injected into the chamber with a manual applicator handheld gun with a 1-mm-diameter injection tip supplied by 3M ESPE. Magic FoamCord was injected into the chamber with a handheld applicator with a 1.5mm-diameter injection tip supplied by Coltène/Whaledent. The pressure was recorded 1000 times per second with a recording system (Powerlab, AD Instruments) with the software Chart, version 5 (AD Instruments). Before each series of tests, or if the testing was interrupted, the pressure gauge was calibrated by placing it into a pressure chamber where a known pressure could be applied. After each test, the silicone
The Journal of Prosthetic Dentistry
and stone compartments were separated and the material was removed. If material residue remained within the chamber space, or if any residue remained on the gauge, it was carefully removed with a microbrush (Microbrush) and orange solvent (Orange Solvent; Dux Dental). A clean microbrush was then used to remove all residues, and the area was dried. Every attempt was made to optimize the delivery of the displacement material; this included the use of new capsules and tips for every test and constant delivery of the material. The gun applicator and injection tip recommended by the manufacturer was used for each of the materials. The gun applicator tip was placed at the base and parallel to the long axis of the chamber for each test. All of the materials were injected into the chamber until the space was overfilled and then the tip of the applicator was slowly retracted while injection continued. All of the tests were performed by 1 operator (M.I.). Each group was tested 15 times, and the median maximum injection pressure (kPa) and median postinjection pressure (kPa) were calculated. The postinjection pressure was determined by averaging the median pressure values from the point at which the applicator was withdrawn to 1 minute after withdrawal. The pressure did not fluctuate and was static after 1 minute. Because of abnormal distribution, the data were analyzed with a KruskalWallis test. A post hoc analysis was then performed with pairwise Mann-Whitney U tests. A Bonferroni
Bennani et al
-
2014
Table I.
3 Injection and postinjection pressure values for Expasyl, Expasyl New, 3M ESPE ARP, and Magic FoamCord in kPa
Injection Pressure Materials Tested Minimum Maximum Median
Postinjection Pressure Interquartile Interquartile Range Minimum Maximum Median Range
Expasyl
144.2
317.4
181.5
67.2
110.4
180.8
142.2
40.9
Expasyl New
120.2
296.6
218.8
62.6
103.2
165.9
127.6
30.7
36.4
111.0
63.6
52.3
24.7
77.8
58.8
26.1
6.6
17.8
9.0
3.3
18.0
43.1
32.8
0.5
3M ESPE ARP Magic FoamCord
correction was then done, and the test was not considered statistically significant unless the P value was less than .05/6¼.0083. All statistical analyses were performed with statistical software (SPSS v19.0.0; SPSS Inc).
RESULTS The minimum, maximum, and median pressures during injection into the silicone chamber and the postinjection pressure values of the 4 different materials are shown in Table I. Expasyl, Expasyl New, and 3M ESPE ARP all had injection pressures greater than their respective postinjection pressures. Magic FoamCord was the only material that had a postinjection pressure greater than the injection pressure. Expasyl New and Expasyl generated the greatest injection pressures, followed by 3M ESPE ARP and then Magic FoamCord. Expasyl New and Expasyl also generated the greatest postinjection pressures, followed by 3M ESPE ARP and then Magic FoamCord. The Kruskal-Wallis test was significant (P
