5.4. Dentine formation
The amounts of the dentine formed during the experimental periods and the results of statistical comparison (independent samples t-test) are given in Table 6. For easier comparison, dentine formation in the second molars (as an example) is also presented in Fig. 11 and 12.
Table 6. Mean dentine formation in three molars in square micrometers x103 during the experimental period.
| Group | 1st Molar | 2nd Molar | 3rd Molar | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| n | Mean | SD | n | Mean | SD | n | Mean | SD | |||
| 6 weeks | |||||||||||
| 1 (m-acid-suc) | 10 | 180 | 25 | 10 | 148 | 32 | 8 | 341 | 34 | ||
| 2 (m-acid-stan) | 10 | 209* | 42 | 11 | 181* | 33 | 12 | 349* | 22 | ||
| 3 (m-alk-suc) | 13 | 206# | 28 | 14 | 168# | 19 | 13 | 368 | 36 | ||
| 4 (m-alk-stan) | 16 | 260 | 34 | 15 | 207* | 23 | 16 | 391 | 34 | ||
| 5 (r-alk-suc) | 14 | 176# | 34 | 14 | 153# | 25 | 13 | 342 | 25 | ||
| 6 (r-alk-stan) | 18 | 243 | 21 | 18 | 204* | 22 | 16 | 357* | 34 | ||
| 7 (norm-suc) | 16 | 197# | 44 | 16 | 170# | 34 | 15 | 353# | 24 | ||
| 8 (norm-stan) | 13 | 262 | 24 | 13 | 242 | 27 | 12 | 398 | 27 | ||
| 7 weeks | |||||||||||
| 9 (m-acid-stan) | 14 | 210* | 27 | 11 | 163* | 21 | 12 | 322* | 45 | ||
| 10 (m-alk-stan) | 18 | 249* | 21 | 18 | 200* | 20 | 155 | 380 | 42 | ||
| 11 (norm-stan) | 17 | 292 | 20 | 17 | 238 | 22 | 168 | 387 | 36 | ||
| Abbreviations: n = number, SD = standard deviation, * = significant difference (connected by ];) between the experimental and corresponding control group (groups 1, 3 and 5 versus group 7, groups 2, 4 and 6 versus 8 and groups 9 and 10 versus 11, each molar separately). # = significant difference (connected by <) between high-sucrose and standard diet group (group 1 versus 2, 3 versus 4, 5 versus 6 and 7 versus 8, each molar separately) (p = 0.01 or less in independent samples t-test). | |||||||||||
Figure 11. Dentine formation in square micrometers in the second molars in the six week"s experiments. The box presents the 1st and 3rd (upper and lower) quartiles with the median value inbetween. The whiskers give the lowest and highest values. n = number of the teeth.
Figure 12. Dentine formation in square micrometers in the second molars in the seven weeks"s experiments. For box plot presentation: see Fig. 11.
According to Table 6, the reducing effect of the high-sucrose diet, as compared to the standard diet on dentine apposition, was visible in all the high-sucrose groups (groups 1, 3, 5 and 7). In the first and second molars it was more apparent (p<0.001 in group 3 vs. group 4, 5 vs. 6, and 7 vs. 8 in both first and second molars, independent samples t-test) than in the third molars. In the third molars, the difference was significant between the groups 7 and 8 (p<0.001).
When the rat groups with an acid-base disturbance and the high-sucrose diet were compared to the controls with the high-sucrose diet (group 1 vs. 7, 3 vs. 7 and 5 vs. 7, each molar separately), no significant differences were found, although the results followed the same patterns as in the groups with the standard diet. The effect of the high-sucrose diet seemed to be independent of the acid-base disturbance.
In the groups with metabolic acidosis and the standard diet (groups 2 and 10), the amount of dentine apposition was reduced in all the molars when compared to those in the control groups (groups 8 and 11) (6 weeks: 1st molar p=0.003, 2nd p<0.001 and 3rd p<0.001, 7 weeks: p<0.001 in all the molars.)
In metabolic alkalosis and the standard diet (groups 4 and 11), a difference (reduction) was found in the second molar (p=0.001) in the group with 6-week"s experimental period (group 4), when compared to the controls with the standard diet (group 8). In the 7-week"s experiment (group 10), the amount of dentine was reduced in the first (p<0.001) and second (p<0.001) molar compared to the controls (group 11).
Statistically significant reduction in the dentine formation was also observed in respiratory alkalosis (group 6) in the second (p<0.001) and third (p=0.002) molars in the rats fed the standard diet for 6 weeks, as compared to the group 8.