الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 142 |  |  |
| | | from | 142 | | |
Abstract
Conclusion and summary
This investigation was conducted to compare MTA and the newly introduced Neo MTA as perforation repair materials in terms of cytocompatibility, biocompatibility, bioactivity, inflammatory tissue reaction, after repair of furcal perforation defect. This study included a cell line part and an animal part to evaluate the various characteristics of the test materials.
In the first part (cell line), both materials were mixed according to manufacturer instructions and after setting the materials were sterilized by UV radiation, Periodontal ligament derived mesenchymal stem cells was the cell line of choice, they were isolated by scrapping the root surfaces of freshly extracted teeth, these cells were incubated and after 20 days a cell culture was obtained, PDLSCs from the third passage were seeded on sample discs to conduct the desired tests, for cytocompatibility and viability MTT tests was carried to evaluate the amount of viable mitochondria that reacted and caused the change in the color of formazan and this color change was evaluated by a spectrophotometer, the MTT test was carried on three consecutive days. Evaluation of Alkaline phosphatase activity The relative ALP activity was measured using Alkaline Phosphatase Assay Kit (Colorimetric). The detection was calorimetric, and the assay was enzyme activity and it was read by a microplate reader, the tests was carried on three consecutive days. The ability of materials to upregulate the gene expression of Bone Sialoprotein was evaluated with RT-PCR test to check the bioactivity of the test materials and ability to promote bone deposition.
The second part was animal study, it was performed on 6 healthy beagle dogs, with a total of 72 teeth, each 2 dogs represented a group with a total of 3 groups according to the follow up periods (1 week, 1 month, 3 months) and in each group 3 subgroups representing the materials under study (MTA, Neo MTA, control), each group consisted of 24 teeth and each subgroup of 8 teeth, in the first visit after the dogs were anaesthetized root canal treatment was completed, and perforations were made in the middle of the furcation area, then the access was left open for the development of osseous lesion, the second visit was after 3 weeks, the dogs were anaesthetized again, the cotton was removed, the perforation site was curetted and cleaned then the perforation was repaired by MTA, Neo MTA or with a cotton then the access was sealed. After the follow up periods according to the groups the dogs were sacrificed and samples were decalcified with EDTA for 120 days, then embedded in paraffin blocks and sectioned. Sections were stained with hematoxylin and eosin for both quantitative and qualitative evaluation. In Quantitative evaluation the histomorphometric analysis was performed using Image J image analysis software and for inflammatory cell count, 4 fields for each section were taken at an original magnification of x40 and the inflammatory cells were counted by the software and tabulated in excel sheet, qualitative analysis of the stained sections to describe the condition of bone surrounding the furcation and the inflammatory condition. All data were collected, tabulated and statistically analyzed.
The results of the MTT assay showed significant difference between the test materials in the 24 hours follow up period where MTA showed the highest number of viable cells followed by the control group then the Neo MTA group, as for the 48 hours follow up period there was a significant difference between the test materials where the control showed the highest number of viable cells followed by Neo MTA group and the MTA was the least to show viability, in the 72 hours follow up period there was significant difference between the control showing the highest number of viable cells followed by the Neo MTA and the MTA group. The effect of time on the behavior of the material was evaluated for the three groups, for the control group there was a significant effect of time on the viability of cells and it was a proportional relationship in the MTA group, time had a significant effect on the viability of cells, as time passed the material had a more toxic effect on cells, in the Neo MTa time as well had a significant effect first it showed a negative response then the viability increased and finally it decreased again, as for the ALP activity we compared the two test materials with each other and there was significant difference as Neo MTA promoted more ALP secretion in the 24-hour evaluation period and this was consistent throughout the 48 hour and 72 hours evaluations. When each material was compared to see the effect of time on its behavior , we concluded that the amount of alkaline phosphatase secreted by PDL derived MSCs subjected to MTA was significantly affected by time where the highest value was seen in the 48 hours follow up followed by the 72 hours then the least amount was seen in the 24 hour evaluation period, the results were similar in the Neo MTA group, there was significant effect of time and the highest value was observed in the 48 hours follow up period followed by the 72 hours evaluation and finally the least value was found in the 24 hours evaluation period. The RT-PCR test was carried and bone -sialoprotein (BSP) was highly expressed by both investigated materials compared with control at day 3. The results of the RT-PCR showed significant difference between the upregulation of BSP gene expression of Neo MTA as compared to MTA, where Neo MTA showed higher expression of the promineralization gene.
In the animal study the results showed significant differences between the control group and when the perforation was repaired with the test materials, the control group showed the highest amount of inflammatory cell infiltrate in the 1 week follow up period and was followed by MTA and the least amount of inflammation was observed in the Neo MTA group, this was consistent in the 1 month follow up period, as there was significant difference between the three test groups with the control showing the highest number of inflammatory cell infiltrate followed by the MTA group and the least amount of inflammation was seen with the Neo MTA group, these results were in line with the 3 months follow up period which showed significant difference between the tested groups and the results were similar ,the Neo MTA showed the least inflammation followed by the MTA group the most inflammatory cell infiltrate was as well seen in the control group. When the materials were put into comparison to evaluate the effect of time on the effect of inflammation, the control group showed no significant difference between the three follow up periods. The highest bone loss and the highest inflammatory cell count mean values at the 3month evaluation period. In the Neo MTA group, the inflammation was higher in the first week then decreased by time.
Based on the results of the current study, the following could be concluded
1. The two tested materials; MTA, Neo MTA provided favorable conditions for periodontal tissue repair following perforation. They could cause regeneration of the adjacent periodontium and hence could be used in furcal perforation repairs.
2. Neo MTA showed less toxicity and better ability to induce secretion of Alkaline phosphatase and bone sialoprotein
3. Healing potentiality of the two materials improved by time.
Recommendations:
1. Further investigations on histological and cellular components are recommended to assess new tricalcium silicate cements.
2. Longer follow up period is needed to evaluate the furcal perforation healing.