Winner 2003 - The IADR.CED Visiting Scholar Stipend

Abdulkadir Sengun

Stipend Recipient:             Abdulkadir SENGUN, DDS, PhD

Department of Conservative Dentistry, Faculty of Dentistry, University of Selcuk, Konya, TURKEY

Hosted by:                           Prof. Dr. Gottfried SCHMALZ

University of Regensburg, Dental School, Operative Dentistry and Periodontology, Regensburg, GERMANY

Duration of the stay:         May 01st –August 31st , 2004

Research topic:                  Cytotoxicity of a Silorane-based Composite in Agar Overlay and Dentin Barrier Tests

Research Objectives:

To evaluate the cytotoxicity of a new silorane-based resin composite material with its corresponding adhesive in comparison with a known material in a dentin barrier test simulating the in vivo situation and by agar overlay test using L-929 mouse fibroblast cell line.

Research Methods:

Three dimensional cultures of SV40 transfected pulp derived Cells (Thonemann and Schmalz, Arch Oral Biol, 45, 857-869, 2000) were transferred into an in vitro dentin barrier test device with dentin slices of 200 and 500 μm thickness. After 24 h incubation at 37°C the test materials were applied into the cavity part of the device: Hermes Composite with its corresponding adhesive (3M ESPE) and Tetric Ceram/Exite (Ivoclar-Vivadent). A light curing glass ionomer cement (Vitrebond, 3M ESPE) was used as reference material and an A-silicone impression material (President, Coltene) as negative control (100% cell vitality).The pulpal part of the device was perfused with cell culture medium. After 24 h exposure, cell survival was measured by MTT test and 15 cultures per material were statistically analyzed (Mann-Whitney-test, α=0.05).

In the agar overlay test, Hermes Composite and its corresponding adhesive (3M ESPE) and Tetric Ceram/Exite (Ivoclar-Vivadent) were tested. A light curing glass ionomer cement (Vitrebond, 3M ESPE) was used as a reference material and an a-silicone impression material (President, Coltene) served as a negative control (100% cell vitality). L929 cells in basal medium Eagle were seeded onto tissue culture dishes and incubated to confluence at 37°C and 5% CO_2.. After 24hours, 3% agar media were poured onto the cell monolayer, and the cells were stained with 0.01% neutral red dye. The solid materials were filled into teflon molds (5 mm diameter, 2mm height). The liquid materials were applied onto a paper disc with 5mm diameter. Two samples were located on one agar plate with positive (PVC) and negative controls and incubated for 24 hours. The width of the decolorization zone, and the percent of cell lysis were obtained, and the toxicity of the materials was interpreted following ISO 7405. Ten plates for one product were statistically analyzed (Mann-Whitney-test, α=0.05).

Results of the Studies:

With 500 μm dentin, cell survival rates for Hermes System (96%) and Tetric Ceram/Exite (98%) were statistically not different from the negative control, but from the reference material (75%). With 200 μm dentin, cytotoxicity of test materials was not changed. However, the glass ionomer cement showed higher cytotoxicity when dentin slices with 200 μm thickness were use (44%).

In the agar overlay test, positive controls showed lysis and a decolorization zone of the fibroblast cells (Li_4, Zi_3) for PVC and (Li_2.5, Zi_2) for Vitrebond, while there was slight lysis and decolorization  zone with the negative control, President (Li_1, Zi_1). Both Excite Bond (Li_1, Zi_3) and Hermes Bond caused lower decolorization  but a similar level of lysis of the fibroblast cells when they were cured. Neither of the composite specimens caused lysis or a decolorization zone (Li_0, Zi_0).

Conclusion: With residual dentin barriers of 200 μm and 500 μm the tested silorane-based composite/adhesive may not alter biologically the dental pulp on a short term basis. In addition, the silorane based composite resin was not toxic, while the bonding of this material was slightly toxic in the in vitro agar overlay test system.

Submitted Abstract:

The abstract was submitted for the Joint Meeting of the Continental European (CED) and the Scandinavian (NOF) Divisions of IADR (Amsterdam, 14 - 17 September 2005).

#0122 Cytotoxicity of a Silorane-Based Composite in a Dentin Barrier Test (A. SENGUN, H. SCHWEIKL, K.-A. HILLER, F. OZER, and G. SCHMALZ)

0122 Cytotoxicity of a Silorane-Based Composite in a Dentin Barrier Test

A. SENGUN¹, H. SCHWEIKL², K.-A. HILLER³, F. OZER¹, and G. SCHMALZ², ¹ Selcuk University, Konya, Turkey, ² Department of Operative Dentistry and Periodontology, University of Regensburg, Germany, ³ University of Regensburg, Germany

The biocompatibility is an important requirement for a dental filling material.

Objective: To evaluate the cytotoxicity of a new silorane-based resin composite material with its corresponding adhesive in comparison with a known material in a dentin barrier test simulating the in vivo situation.

Methods: Three dimensional cultures of SV40 transfected pulp derived Cells (Thonemann and Schmalz, Arch Oral Biol, 45, 857-869, 2000) were transferred into an in vitro dentin barrier test device with dentin slices of 200 and 500 mm thickness. After 24 h incubation at 37°C the test materials were applied into the cavity part of the device: Hermes Composite with its corresponding adhesive (3M ESPE) and Tetric Ceram/Exite (Ivoclar-Vivadent). A light curing glass ionomer cement (Vitrebond, 3M ESPE) was used as reference material and an A-silicone impression material (President, Coltene) as negative control (100% cell vitality).The pulpal part of the device was perfused with cell culture medium. After 24 h exposure, cell survival was measured by MTT test and 15 cultures per material were statistically analyzed (Mann-Whitney-test, α=0.05).

Results: With 500 mm dentin, cell survival rates for Hermes System (96%) and Tetric Ceram/Exite (98%) were statistically not different from the negative control, but from the reference material (75%). With 200 mm dentin, cytotoxicity of test materials was not changed. However, the glass ionomer cement showed higher cytotoxicity when dentin slices with 200 mm thickness were use (44%).

Conclusion: With residual dentin barriers of 200 mm and 500 mm the tested silorane-based composite/adhesive may not alter biologically the dental pulp on a short term basis.
This paper is competing for the following awards: CED Travel Stipend

Joint Meeting of the Continental European and Scandinavian (NOF) Divisions of the IADR (September 14 - 17, 2005)

0207 Effect of Acid Etching and Bonding Systems on Microleakage

M. DEMIRCI¹, F. OZER², M. KUSDEMIR², H. SAR SANCAKLI¹, S. KARAKAYA², and A.K. SENGUN², ¹ University of Istanbul, Turkey, ² Selcuk University, Konya, Turkey

Objectives: The aim of this study was to compare of microleakage of different bonding systems and cavity etching in class V cavities.

Methods: Class V cavities were prepared both on facial and lingual surfaces of 30 noncarious, extracted human premolar teeth. Preparations were centered on the cementoenamel junction and approximately 2 mm deep, 2 mm in height and 3mm in width. 60 cavities on 30 teeth were divided into six group. Each group had 10 cavities. The group 1 was restored Scotchbond Multipurpose and Z 250 (3M), group 2: Clearfil Protect Bond and Clearfil ST (Kuraray), group 3: Reactmer Bond SET and Reactmer Paste (Shofu), group 4: Reactmer Bond SET ve Reactmer Paste (Shofu) after etching procedure, group 5: Prime Bond NT and Dyract Extra (Dentsply), group 6: Prime Bond NT and Dyract Extra (Dentsply) after etching procedure. The specimens were stored in distilled water for one week at room temperature and thermocycled for 1000 cycles (at 5oC to 55oC; 15-second dwell time). After immersion in 0.5% basic fuchsin dye for 24 hours, the teeth were washed for 15 minutes under running water, sectioned longitudinally and evaluated for dye penetration using a binocular stereomicroscope by two examiners.

Results: Statistical analysis (Kruskal-Wallis, Mann-Whitney U-test) revealed significant differences (P<0.05) between the group 5 and group 1, 2, 3 at occlusal wall for the microleakage scores. At the gingival wall, there was significant difference between the group 6 and the group 2 and 5.

Conclusion: Prime Bond NT with Dyract Extra showed significant microleakage at occlusal wall than other bonding systems and acid etching did not effect sealing of Prime Bond NT and Reactmer Bond SET. At gingival wall; also Prime Bond NT with Dyract Extra revealed more leakage than other bonding system and acid etching effected sealing capacity of Prime Bond NT negatively.

Joint Meeting of the Continental European and Scandinavian (NOF) Divisions of the IADR (September 14 - 17, 2005)

0055 Volumetric Polymerization Shrinkage and Water Sorption of Restorative Resin Materials

F. ÖZER, N. ÜNLÜ, A. SENGUN, and Y. SENER, Selcuk University, Konya, Turkey

Objectives:The purpose of this study was to compare the volumetric polymerization shrinkage and water sorption of eight different restorative resin materials (Admira-Voco, Ælite-Bisco, Surefil-Dentsply, Artglass-Heraeus Kulzer, Estenia-Kuraray, Clearfil Photo Posterior-Kuraray, Polofil Supra-Voco, P60-3M Espe).

Methods:120 glass rings 8 mm in diameter and 2 mm high were used in the study. The density and volume of the rings were calculated . 15 specimens were made by light or heat curing of each material. The specimens were weighed in air and in water to calculate final volumetric shrinkage (%) values of materials and then placed in distilled water at 37° C for 30 days. Water sorption was assessed gravimetrically as a percentage mass change. For statistical analysis One Way ANOVA and Tukey HSD tests were used.

Results:

Materials                               Shrinkage                              Water Sorption

Mean±S.D (%)                     Mean±S.D (%)

Admira (A)                            2.77 ± 0.97 ^b,c                         0.53 ± 0.10 ^b,c

Ælite (AE)                              2.54 ± 0.84 ^a,b,c                       0.34 ± 0.18 ^b

Surefil (S)                              2.99 ± 0.89 ^b,c                         1.34 ± 1.00 ^c,d

Estenia (E)                             2.30 ± 0.76 ^a,b                         0.16 ± 0.07 ^a

Clearfil Photo Posterior (CPP)1.68 ± 0.91 ^a                          0.11 ± 0.07 ^a

Artglass (AG)                        2.46 ± 0.46 ^a,b                         0.35 ± 0.14 ^b,c

Polofil Supra (PS)                  4.16 ± 0.81 ^d                           2.35 ± 1.14 ^d,e

P60 (P)                                  3.42 ± 0.72 ^c,d                         3.73 ± 1.82 ^e

Means with same supercript letter at same column are not statistically different (p>0.05).

CPP exhibited the lowest volumetric shrinkage and followed by E, AG and AE. PS showed the highest shrinkage. Water sorption was also low for the materials CPP and E. The materials with high polymerization shrinkage also revealed high water sorption.

Conclusions: The shrinkage and water sorption behaviour of materials tested seem to be related to the organic matrix and chemical composition of the fillers.

IADR/AADR/CADR 82nd General Session (March 10-13, 2004)

3110 Effect of Antimicrobial Agents on Bond Strength

S. MALKOC¹, A. DEMIR¹, A. SENGUN¹, and F. OZER², ¹ Selcuk University, Konya, Turkey, ² University of Selcuk, Konya, Turkey

Objective: The aim of this present study was to determine whether the application of different antibacterial agent containing primers (Micro PrimeTM, Seal Protect, and Gluma Desensitizer) can affect the shear bond strength of an orthodontic resin composite.

Methods: Seventy two crowns of extracted lower human incisors were mounted in acrylic resin by leaving their vestibule faces parallel to the base of the molds. The teeth were randomly divided into three experimental groups and one control group, each containing 18 teeth. In each experimental group, the primers were applied to the etched enamel surfaces. In control group, antibacterial primer was not used. An orthodontic composite resin(Transbond XT,3M Unitek)was applied to the surface into cylindrical shaped plastic matrixes after an orthodontic bonding agent (Transbond XT, 3M Unitek) application. For shear bond testing a stubby-shape apparatus (Ultradent, USA) was applied at a cross head speed of 1 mm/min to each specimen at interface between tooth and composite until failure occurred. Kruskal Wallis one way ANOVA and Mann Whitney-U with a Bonferroni adjustment test were used for statistical analysis.

Results: There was no significant difference between the bond strength values of Seal&Protect (27.98±8.73) and control (35.15±7.85) groups (p>0.05). However, Gluma (21.61±7.96) and Microprime (14.89±5.55) caused a decrease in bond strength of the orthodontic bonding agent(p<0.05).

Conclusion: Since triclosan containing Seal&Protect did not cause any change in bond strength, it is advisable to use it under orthodontic resin composites to get benefit from its antibacterial effect.

IADR/AADR/CADR 82nd General Session (March 10-13, 2004)