Histocompatibility of Light-Curing Composites Used in Pediatric Dentistry in Human Oral Fibroblast Cells.

Statement of the Problem: Tooth-colored composites are used to repair caries lesions and other dental defects, particularly in anterior regions in children. Although a wide range of composites is using, little attention has been paid to the important indicators such as biological profiles or products released from these materials. Purpose: The current study aimed to compare the histocompatibility and cytotoxicity of light-curing resin used to repair children's teeth with different brands (3M, DenFil, and Opallis) in curing times of 20 and 40 seconds in human oral fibroblast cells (HGF1). Materials and Method: In this in vitro study, Three types of flow composites (3M, Opallis, and DenFil), all at A2 shade, were used. The composites were at 4×2mm with separate exposure times of 20 and 40 seconds. MTT test was used to determine the cytotoxicity of composites on oral fibroblast cells. This test is based on the conversion of tetrazolium bromide to a purple compound known as formazan that its color intensity can be evaluated using the ELISA. The higher intensity of the color reveals the higher survival rate of the mitochondria, which indicates less toxicity. One-way variance analysis and unpaired t-test were used to compare the cytotoxicity of each brand in two conditions of 20 and 40 seconds of curing. Statistical significance was considered when p< 0.05. Results: 3M and Opallis composites were significantly reduced vitality of cells compared to control group in both 20s and 40s curing status. While DenFil brand did not show marked cytotoxicity. In each brand, there are no significant deference between 20s and 40s curing times. Conclusion: Histocompatibility depends on the type of composite resin. In the current study, DenFil brand showed the highest histocompatibility, followed by 3M and Opallis.

Comparison of Marginal Circumference of Two Different Pre-Crimped Stainless Steel Crowns for Primary Molars After Re-Crimping.

OBJECTIVES: It is not clear what type of pre-crimped crown is more successful in achieving greater marginal adaptation following re-crimping. This study aimed to assess the changes in the circumference of 3M ESPE and MIB pre-crimped stainless steel crowns (SSCs) for the primary maxillary and mandibular first and second molars following re-crimping. MATERIALS AND METHODS: This was an in-vitro, experimental study. Initial photographs were obtained from the margins of 3M and MIB SSCs for the upper and lower primary molars using a digital camera. Crown margins were crimped by applying 0.2N force using 114 and 137 pliers. Post-crimping photographs were also obtained and the changes in crown circumference after crimping were calculated using AutoCad software. The percentage of reduction in the circumference of crowns for each tooth was statistically analyzed based on the type of crown using student t-test. The effect of crown design and the associated teeth on the decreased circumference percentage was statistically analyzed by two-sided ANOVA. RESULTS: The percentage of reduction in lower E SSC circumference was 3.71±0.39% in MIB and 6.29±0.62% in 3M crowns. These values were 3.55±0.55% and 7.15±1.13% for the lower Ds, and 3.95±0.43 and 6.24±0.85% for the upper Ds, respectively. For the upper Es, these values were found to be 3.12±0.65% and 5.14±0.94%, respectively. For each tooth, a significant difference was found between MIB and 3M SSCs in terms of the percentage of reduction in crown circumference following crimping. The magnitude of this reduction was smaller in MIB compared to 3M SSCs (P<0.001). CONCLUSION: Considering the significant reduction in the marginal circumference of precrimped SSCs following re-crimping, it appears that this manipulation must be necessarily performed for MIB and 3M pre-crimped SSCs. By using 3M SSCs, higher marginal adaptation can be achieved following crimping.

In vitro computer analysis of crown discolouration from commonly used endodontic sealers.

The aim of this study was to assess the degree of staining of tooth crowns by commonly used endodontic sealers using a computer analysis method. Crown discolouration by root canal sealers AH26, Endofill, Tubliseal, Zinc oxide eugenol (ZnOE), Apatite root canal sealer III as well as gutta-percha and Cavizol (a filling material containing ZnOE) were tested on extracted human premolar teeth. The roots of the teeth were resected 3 mm below the cemento-enamel junction. The pulp chambers were then cleaned and irrigated. The samples were divided into nine groups of five samples each and filled with test materials. Ten teeth were used as control groups: five positive (amalgam) and five negative (distilled water). The degree of tooth discolouration was analysed at 3, 6 and 9 months. The crown discolouration was assessed by computer analysis of digital images taken from the samples using the CIE Lab colour system. Statistical analysis was carried out using anova, repeated measure anova and Tukey's HSD tests. All sealers caused a degree of tooth discolouration, which increased with time. Endofill and ZnOE caused the greatest discolouration and Apatite root canal sealer III caused the least discolouration after 9 months. The most discolouration during the test periods occurred in the cervical third of the crown.