3.1. Clinical results:
There were no complications or other urgent clinical concerns during the surgical operations or the follow-up period. No postoperative complications or apparent infection were found. Moreover, no implant was excluded from the research.
3.2. Histological results
3.2.1. Haematoxyline and Eosin stain
In the control group, histological examination revealed a wide area of compact bone composed of numerous Haversian systems (Fig. 2).
At day zero
Subgroup IA (traditional drilling) showed thermal osteonecrosis which yields an area with few empty lacunae around this necrosis and microcracks were obviously seen around the drilling site (Fig. 3 a-c). In contrast, subgroup IB (Densah drilling) showed remnants of bone chips enclosing osteocytes which were compressed into the trabecular bone spaces adjacent to the osteotomy wall (Fig. 3 d-f). Also, cracks were rarely seen on the osteotomy wall in subgroup IB.
After 2 months
Subgroup IIA revealed no newly formed osteons at the cervical portion of the bone-implant interface and the inter thread area was occupied by granulation tissue and bone spicules (Fig. 4 a). In the middle portion of the specimen there were newly formed osteons in the inter thread bone. Newly formed woven bone was evident in the middle and apical portions of the specimen but with lesser amount in the apical than the middle portion (Fig. 4 b,c).
Subgroup IIB demonstrated areas of new bone formation and complete disappearance to all bone chips along the entire implant surface and the inter thread area indicating bone remodeling. In the cervical and middle portions of the specimens there were newly formed osteons in proximity to the implant surface. Ossification centers surrounded by extensive network of large blood vessels were obvious in the apical portion at the vicinity of the implant surface (Fig. 4 d-f).
3.2.2. Masson trichrome stain
Masson trichrome stain was used to illustrate the different stages of collagen maturation. Irregularly arranged immature collagen fibers of woven bone stained blue while mature osteons-stained red. Specimens of the control group, group I and group II showed mature osteons stained red, with small immature areas stained blue (Fig. 5 a-c).
Subgroup IIA revealed areas of woven bone formed of irregularly arranged collagen fibers in the most cervical part of the inter thread area. Then moving towards the middle part, the inter thread bone was formed of a rim of mature bone stained red and woven bone stained blue (Fig. 6 a,b). While subgroup IIB revealed areas of woven bone which were present along the entire implant surface and the inter thread area. Moreover, areas of newly formed osteons surrounded by woven bone were evident in proximity to the implant surface especially in the cervical and middle portions (Fig. 6 c,d).
3.3. Histomorphometric analysis:
3.3.1. Statistical analysis of area percentage of newly formed bone (H&E stain):
A significantly higher mean value was recorded in subgroup IIB (22.26±2.58%), in comparison to subgroup IIA (11.11±0.82%). The difference between both subgroups was statistically significant (P=0.000), (Table 1)
Table (1): Descriptive statistics and comparison of bone area percentage (%) using H&E stain (independent t-test).
Groups
|
Mean
|
Std. Dev
|
Difference
|
T
value
|
P
value
|
Mean
|
Std. Dev
|
C.I. lower
|
C.I. upper
|
group IIA
|
11.11
|
.82
|
11.15
|
1.21
|
8.36
|
13.94
|
9.21
|
.000*
|
group IIB
|
22.26
|
2.58
|
|
|
|
|
|
|
Significance level p≤0.05, *significant, C.I. 95% Confidence Interval of the Difference
3.3.2. Statistical analysis of area percentage of newly formed bone (Masson trichrome stain)
A significantly higher mean value was recorded in subgroup IIB (14.55±1.13%), in comparison to subgroup IIA (10.70±1.07%). The difference between both groups was statistically significant (P=0.001), (Table 2)
Table (2): Descriptive statistics and comparison of bone area percentage (%) using Masson trichrome stain (independent t-test).
Groups
|
Mean
|
Std. Dev
|
Difference
|
T
value
|
P
value
|
Mean
|
Std. Dev
|
C.I. lower
|
C.I. upper
|
group IIA
|
10.70
|
1.07
|
3.85
|
.70
|
2.25
|
5.46
|
5.54
|
.001*
|
group IIB
|
14.55
|
1.13
|
|
|
|
|
|
|
Significance level p≤0.05, *significant, C.I. 95% Confidence Interval of the Difference
3.3.3. Statistical analysis of bone density using CBCT (control, subgroup IA and subgroup IB)
Buccal bone:
The mean value in control group was (1123±30.36), in comparison to subgroup IA (1026.75±15.71) and subgroup IB (1164.75±143.57). The difference between groups was not statistically significant (P=0.066), (Table 3a, b)
Palatal bone:
The mean value in control group was (1089.75±85.89), in comparison to subgroup IA (1070.25±168.43) and subgroup IB (1187±53.32). The difference between groups was not statistically significant (P=0.258), (Table 3a, b)
Table (3a): Descriptive statistics and comparison of buccal and palatal bone density (ANOVA test).
|
Mean
|
Std. Deviation
|
95% Confidence Interval for Mean
|
Min
|
Max
|
F
value
|
P
value
|
Lower Bound
|
Upper Bound
|
Buccal
|
Control
|
1123.00
|
30.36
|
1085.30
|
1160.70
|
1091
|
1173
|
3.449
|
.066
ns
|
group IA
|
1026.75
|
15.71
|
1007.25
|
1046.25
|
1007
|
1050
|
|
|
group IB
|
1164.75
|
143.57
|
986.48
|
1343.02
|
1011
|
1398
|
|
|
Palatal
|
Control
|
1089.75
|
85.89
|
983.10
|
1196.40
|
961
|
1197
|
1.520
|
.258
ns
|
group IA
|
1070.25
|
168.43
|
861.11
|
1279.39
|
872
|
1301
|
|
|
group IB
|
1187.00
|
53.32
|
1120.79
|
1253.21
|
1116
|
1256
|
|
|
Significance level p≤0.05, ns=non-significant
Table (3b): Results of Bonferroni post hoc test for pairwise comparison of buccal and palatal bone density.
Dependent Variable
|
(I) Drilling
|
(J) Drilling
|
Mean Difference (I-J)
|
Std. Error
|
95% Confidence Interval
|
P value
|
Lower Bound
|
Upper Bound
|
Buccal
|
Control
|
group IA
|
96.25
|
53.89
|
-53.54
|
246.04
|
.30 ns
|
group IB
|
-41.75
|
53.89
|
-191.54
|
108.04
|
1 ns
|
group IA
|
Control
|
-96.25
|
53.89
|
-246.04
|
53.54
|
.30 ns
|
group IB
|
-138.00
|
53.89
|
-287.79
|
11.79
|
.07 ns
|
group IB
|
Control
|
41.75
|
53.89
|
-108.04
|
191.54
|
1 ns
|
group IA
|
138.00
|
53.89
|
-11.79
|
287.79
|
.07 ns
|
Palatal
|
Control
|
group IA
|
19.50
|
71.73
|
-179.88
|
218.88
|
1 ns
|
group IB
|
-97.25
|
71.73
|
-296.63
|
102.13
|
.60 ns
|
group IA
|
Control
|
-19.50
|
71.73
|
-218.88
|
179.88
|
1.00
|
group IB
|
-116.75
|
71.73
|
-316.13
|
82.63
|
.39 ns
|
group IB
|
Control
|
97.25
|
71.73
|
-102.13
|
296.63
|
.60 ns
|
group IA
|
116.75
|
71.73
|
-82.63
|
316.13
|
.39 ns
|
Significance level p≤0.05, ns=non-significant
3.3.4 Statistical analysis of bone density using CBCT (Subgroup IIA and subgroup IIB)
Buccal bone:
A significantly higher mean value was recorded in subgroup IIB (1678.75±73.37), in comparison to subgroup IIA (919.5±220.84). The difference between both groups was (759.25±104.07) which was statistically significant (P=0.000), (Table 4)
Palatal bone:
A significantly higher mean value was recorded in subgroup IIB (1785±213.68), in comparison to subgroup IIA (1186.5±71.32). The difference between both groups was (598.5±100.74) which was statistically significant (P=0.000), (Table 4)
Table (4): Descriptive statistics and comparison of bone density using CBCT (independent t-test).
|
Groups
|
Mean
|
Std. Dev
|
Difference
|
T
Value
|
P Value
|
|
Mean
|
Std. Dev
|
C.I. lower
|
C.I. upper
|
Buccal
|
group IIA
|
919.50
|
220.84
|
759.25
|
104.07
|
519.26
|
999.24
|
7.3
|
.000*
|
group IIB
|
1678.75
|
73.37
|
|
|
|
|
|
|
Palatal
|
group IIA
|
1186.50
|
71.32
|
598.50
|
100.74
|
366.19
|
830.81
|
5.94
|
.000*
|
group IIB
|
1785.00
|
213.68
|
|
|
|
|
|
|
Significance level p≤0.05, *significant