Journal of Dental Medicine

Statement of Problem: One of newly presented base metal alloys (Minalux) is produced according to VeraBond2 alloy (Ni- Cr base) composition. Several studies showed that, cytotoxicity of base metal alloys can be occurred due to corrosion and element release.

Purpose: This study evaluated the biocompatibility of these two base metal alloys in three steps: as cast, after polishing and after porcelain firing cycles. Release of Ni and Cr ions were measured to determine if there is any difference between these two alloys.

Materials and Methods: Samples of two base metal alloys were subjected to Neutral Red Assay, MTT Assay and Trypan Blue for biocompatibility tests. Fibroblast Balb/c 3T3 cells were used for cell culture. Samples were contacted directly with cells in 37ºc and 5% Co2 concentration for 72 hours. Teflon samples were used as negative control. ANOVA test was used to compare different groups of two alloys. In addition, the release of Ni and Cr ions in to saline solution was measured by means of atomic absorption spectrometry.

Results: MTT and Trypan Blue didn’t show any significant difference between Minalux, VeraBond2 and Teflon. Neutral Red Assay showed no significant difference between these two base metal alloys but as cast group was higher in cytotoxicity in comparisons with polished and firing groups in both two alloys. Release of Cr ion was non detectable (Cr < 1 PPB) but Ni ion was measured and Ni release was significantly different in as cast groups (P=0.007) of two alloys.

Conclusion: There is no significant difference between cytotoxicity of two base metal alloys and polishing and firing can decrease cytotoxicity of both alloys.

Background and Aims: Despite the significant improvement in dentistry, pain after endodontic therapy is still of concern for patients. Non-steroidal anti-inflammatory drugs are the most commonly prescribed oral analgesics used for dental pain relief after root canal treatment. The purpose of this study was to compare the effectiveness of Ibuprofen versus slow-released Diclofenac Sodium in controlling pain following root canal treatment.

Materials and Methods: In this randomized clinical trial, mandibular molars with irreversible pulpitis in 90 patients were selected. The patients were divided into three groups (Ibuprofen, slow-released Diclofenac Sodium and placebo). After examination patients filled in the consent form. Then they received one of the mentioned drugs. After inferior alveolar nerve block, access cavity was prepared and the root canals were prepared using passive step back method. The canals were dried and temporary filling material was placed. Then the pain evaluation form (visual analog scale) was explained and delivered to the patients. Data were analyzed using Repeated Measurement ANOVA, Kruskal-wallis and Man-Whitney U tests.

Results: The mean pain intensity in slow-released Diclofenac Sodium group was 0.87 0.95, 1.17 1.10 for Ibuprofen group, and 2.14  1.70 for placebo group. The differences between groups were statistically significant (P<0.001). The effect of Ibuprofen in controlling post endodontic pain in the first 2 hours was more than slow-released Diclofenac Sodium (P=0.01), but in 10, 18, and 36 hours after treatment, slow-released Diclofenac Sodium was more effective than Ibuprofen (P<0.001).

Conclusion: Premedication with single dose of slow-released Diclofenac Sodium can control post endodontic pain for a longer period of time compared with Ibuprofen.

.

Background and Aims: In spite of the advances achieved in the field of dentin adhesives, the longevity of bond to dentin is still a challenge. According to recent studies, Matrix Metaloproteinase (MMP) inhibitors can increase clinical longevity of bonding and decrease leakage. The aim of this study was to evaluate the amount and pattern of doxycycline release from an experimental dentin adhesive containing this MMP inhibitor.

Materials and Methods: In this experimental study, specimens containing 0.25 and 0.5 loading percent of doxycycline in an experimental monomer were prepared in cylindrical moulds of 12 mm diameter and 2 mm thickness. The adhesive monomer was composed of 12 wt% Bis-GMA, 10 wt% TMPTMA, 28 wt% HEMA and 50 wt% ethanol. Camphorquinone and amine were used as initiators.

Results: Addition of 0.25 and 0.5 w% doxycycline showed linear release in both groups. Increasing the loading percent of doxycycline caused more release. The release continued during the test period.

Conclusion: Doxycycline release was observed from the experimental adhesive. Further studies in this field will help in preparing adhesive systems with more clinical longevity.

Background and Aims: Considering the application of recycled metallic brackets in orthodontic treatments and probably more resultant metal ion release, which can cause cytotoxic side effects, this study was set up to assess the effect of recycling process of orthodontic brackets on metal ion release.
Materials and Methods: In this experimental study, 80 Discovery direct bond brackets (Dentarum, Germany) were divided into 2 groups, new and recycled brackets (n = 40), then each group was divided into two subgroups (one-week and 6-months subgroups) (n=20). The specimens were maintained in buffered solution of NaNHNo3 (pH=7) at 37°C in an incubator. After periods of one week and 6 months immersion, 0.5 mL of each solution was analyzed by spectrophotometry for the quantity of released Nickel (Ni), Chromium (Cr), and Cobalt (Co) ions. The data were analyzed using two way ANOVA analysis.
Results: After one week, the quantity of Ni, Cr, and Co ions released from new brackets were 0.65, 1.4, and 0.75 (ppb), respectively. The values for recycled brackets were 142, 2.61, and, 1.43 (ppb). These findings indicated significant difference between two groups (P<0.001). After six months, the quantity of Ni, Cr, and Co ions released from new brackets were 1200, 3.4, and 2.4 (ppb) and from recycled brackets were 2330, 6.9, and 10.8 (ppb), which showed significant difference between two groups (P<0.001).
Conclusion: Application of recycled brackets in long fixed orthodontic treatments can lead to metal ion release, specifically Nickel. Thus, the use of recycled brackets in long orthodontic treatments is not recommended.