The gene expression patterns were obtained for the immediate and delayed group for day 1, 3 and 7 by comparing it with 0 hours delayed and 0 hour immediate as the control for the corresponding immediate and delayed group for temporal comparison. For conditional comparison the delayed group was compared with the immediate of the same time point. Nine possible comparisons were done between the 3 replicates. Samplewise hierarchical clustering approaches were performed for PDL as well as Bone to visualize the consistency of gene expression pattern among the various replicate comparisons.
12, Results & Discussion
12.2.1 Periodontal ligament
12.2.1.1 Temporal comparison
In the immediate group, all the nine comparisons were clustered together in their respective time points i.e. day 1, 3 and 7. The comparisons for Day 3 and Day 7 were linked to each other and the dendogram links of Day 7 were at a lower level than that of Day 3 comparisons. The above findings suggested that the expression patterns were consistent and distinct at day 1, 3 and 7 and likely to be beyond genetic variation and more pronounced and distinct at day 7 (Figure 3).
In the delayed group, the nine comparisons for day 1 were clustered together. Three comparisons from day 3 and 7 formed a separate cluster. The remaining 6 comparisons for day 3 and 7 were clustered in their respective time points. These findings suggested that compared to the immediate group, there was lower expression with increasing level beyond day 1(Figure 19) This low level of expression might be related to the RNA degradation due to damage incurred from trauma and extra oral dry period on the PDL in the delayed- replanted group .(Figure 4)
The combined clusters for the immediate and delayed comparisons showed low level of genetic expression at day 1 in both the immediate and delayed groups. The pattern differed thereafter in the two groups, with the immediate group showing more genetic expressions than the delayed group. This is in line with the previous understanding that in the delayed- replanted group, the PDL on the root surface had been damaged while in the immediate- replanted group, the PDL remained viable and are able to bring about biological events leading to optimal healing (Figure 5).
12.2.1.2 Conditional comparison
hour were clustered together. The clustering pattern suggests that biological response at 0 hour and 1 day are similar in the periodontal ligament in the delayed group and the changes are not beyond genetic variation. But at day 3 and day 7 the pattern becomes more distinct and at day 7 biological responses is better as compared to day 3, this conclusion about the biological response on day 7 is based on prior knowledge that samples that have similar biological response unify with the most similar pair gradually reducing till all the genes are united as to be one union as a result of this pairing the height of the dendogram is the lowest and distance greatest from the unpaired genes (Figure 9). Following avulsion, PDL is exposed to a lot of environmental stress and the response of the PDL cells in different animals and among different tooth might be variable. For PDL, the factor of genetic variation seems to be dominant over the biological response elicited by PDL in the delayed group and this probably results in an inconsistent pattern seen at day 1 and at 0 hour. Another possibility could be that RNA degradation may have occurred at the delayed group and therefore a consistent change must have been observed when delayed group was compared with immediate group.
12.2.2 Alveolar bone
12.2.2.1 Temporal comparison
For alveolar bone in both the immediate (Figure 6) and delayed (Figure 7) group all the nine comparisons were clustered together in their respective time points. The clusters for Day 3 and Day 7 were linked to each other and the dendogram links of Day 7 were at a lower level than that of Day 3 comparisons. The above findings showed that the expression patterns were consistent and distinct at day 1, 3 and 7 and the biological processes were independent of genetic variation and more progressive and distinct at day 7.
The combined cluster for the immediate and delayed group showed a very distinct pattern of expression both within the groups and between the time points. Unlike in the
12, Results & Discussion
periodontal ligament, biological process in the alveolar bone is very distinct from day 1 between the immediate and delayed group (
Table 10: Condition comparison: Alveolar Bone)
12.2.2.2 Conditional comparison
The nine comparisons for day 3, 7 and 0 hour were grouped together in their respective cluster. 3 comparisons from day 1 were linked with the day 7 cluster. The dendogram links of day 3 and day 7 were at a lower level as compared to day 7 and 0 hour.
Unlike in the periodontal ligament the biological process are distinct from the onset that is 0 hour and shows a very distinct pattern right from day 3. (Figure 10)
Following avulsion, unlike PDL the alveolar bone retains its vascular and nutritional supply and is better equipped to overcome the side effects of exposure to the environmental stresses. When compared to the PDL in the delayed group the alveolar bone in the same group shows a more distinct biological pattern at all the observation time points.
12.2.3 Topographic comparison
12.2.3.1 Temporal comparison
Topographic comparison between the PDL and the alveolar bone in the immediate group showed a very distinct pattern of cluster for both the tissues. All the 9 comparisons are grouped together in their respective clusters for time point 1, 3 and 7 day. Biological response between bone and PDL is distinct at day 3 and 7. Biological response on day 1 is different in the two tissues but not beyond biological variation. Biological response shown by bone is better than that for PDL. This conclusion is based on prior knowledge that samples that have similar biological response unify with the most similar pair gradually reducing till all
dendogram is the lowest and distance greatest from the unpaired genes This pattern is more evident in the bone (Figure 11).
In the delayed group a very distinct pattern of cluster is evident for alveolar bone.
Biological response following avulsion between alveolar bone and PDL is different at the beginning right from day 1. Biological response is better at day 7 as compared to day 3 for PDL, but difference is not beyond the genetic variation. The expression pattern at day 3 and 7 are similar but the biological response is better on day 7 and is beyond genetic variation (Figure 12).
12.2.3.2 Conditional comparison
Topographic comparison for the conditions showed that the clusters for day 3 and 7 showed a distinct pattern. At 0 hour and day 1 the healing response is not beyond genetic variation for both alveolar bone and PDL in the delayed group as compare to the immediate group. Biological process in bone is more distinct. (Figure 13)