From 2013 to 2017, 121 young permanent teeth in 115 patients were treated with REPs. By June 2019, 4 patients with 4 teeth were lost within one year follow-up, and 1 tooth was extracted because of orthodontic requirements within 1 year after REPs. Therefore, a total of 116 teeth in 110 patients were included in this study. The included patients’ demographic and clinical details were shown in Supplementary 2 and 3, and Table 1 summarized the demographic and clinical data of the study population. The age of the patients ranged from 7 to 13 years old. The average age of trauma group was 8.9 ± 0.5 years old and that of dens evaginatus group was 10.9 ± 0.8 years old.
Table 1
Demographics and Clinical Data of the Study Population
Variables
|
Categories
|
N (%)
|
Age
|
Years (mean ± SD)
|
10.3 ± 0.7
|
Gender
|
Male
|
52 (47.3%)
|
|
Female
|
58(52.7%)
|
Tooth type
|
Maxillary central incisors
|
32 (27.6%)
|
|
Maxillary lateral incisors
|
2 (1.7%)
|
|
Maxillary second premolars
|
3 (2.6%)
|
|
Mandibular second premolars
|
76 (65.5%)
|
|
Mandibular first premolars
|
3 (2.6%)
|
Aetiology
|
Dental trauma
|
34 (29.3%)
|
|
Dens evaginatus
|
82 (70.7%)
|
Preoperative diagnosis
|
Asymptomatic apical periodontitis
|
77 (66.4%)
|
|
Symptomatic apical periodontitis
|
18 (15.5%)
|
|
Chronic apical abscess
|
16 (13.8%)
|
|
Acute apical abscess
|
5 (4.3%)
|
Apical foramen size in trauma group
|
mm (median)
|
3.00
|
Apical foramen size in dens evaginatus group
|
mm (median)
|
2.65
|
Root length in trauma group
|
mm (median)
|
12.9
|
Root length in dens evaginatus group
|
mm (median)
|
11.50
|
Root thickness in trauma group
|
mm (median)
|
1.41
|
Root thickness in dens evaginatus group
|
mm (median)
|
1.41
|
Among all 116 cases, only 1 case was retreated with apexification due to infection recurrence 3 months after REPs, and 115 cases achieved apical healing and were clinically asymptomatic, reaching a success rate of 99.1% by the primary goal of AAE. Root development was analysed by comparing the CBCT images at the 1-year follow-up (Supplementary 4) to the preoperative CBCT images. A total 104 out of 116 teeth achieved root development (Type I, II or III), with a rate of 89.7% by the secondary goal of AAE. The dens evaginatus group had Type I 86.6% (71/82 cases), Type II 9.8% (8/82 cases), Type III 2.4% (2/82 cases), and Type IV 1.2% (1/82 cases), while the trauma group had Type I 44.1% (15/34 cases), Type II 2.9% (1/34 cases), Type III 20.6% (7/34 cases) and Type IV 32.4% (11/34 cases). The statistical analysis showed a significant difference in the outcome distribution between the dens evaginatus group and trauma group (P < 0.001) (Table 2), indicating that aetiology may affect the root development of REPs.
Next, whether preoperative periapical diagnosis would influence the outcomes of REPs was evaluated. Table 2 showed that most cases achieved Type I outcomes despite different preoperative diagnoses, and overall, no significant difference was found among the four types of distribution of treatment outcomes based on the preoperative diagnosis (P > 0.05), suggesting that preoperative diagnosis may not influence root development of REPs.
The effect of age on REPs outcomes was also analysed. Considering that the overall range of patients’ ages was relatively small (7 to 13 years old), we first analysed the effect of each age subgroup on the outcome of REPs (7, 8, 9, 10, 11, 12, 13 years old) and found no significant difference among all age groups within each aetiology group. Next, the average ages of the dens evaginatus group and trauma group (10.9 and 8.9 years old, respectively) were used for further statistical analysis, and there was no significant difference among them (≥ 10.9 years old. vs. <10.9 years old in the dens evaginatus group and ≥ 8.9 years old vs. <8.9 years old in the trauma group) (P > 0.05) (Table 3).
Statistical analysis was also performed to determine whether preoperative root morphology (apical foramen size, root length and thickness) affected outcomes of REPs. First, we analysed whether there was any difference in REPs outcomes among each range of apical foramen size (1, 2, 3 mm), root length (8, 9, 10, 11, 12 mm) and root wall thickness (1.2, 1.3, 1.4 mm) and found no significant difference among each range. Thus, the median values of these three indexes were calculated for statistical analysis. In the dens evaginatus group, preoperative root morphology did not affect the root development of REPs (P > 0.05) (Table 4). In the trauma group, only the teeth with apical foramen sizes larger than 3 mm achieved significant root development than those smaller than 3 mm (P < 0.01) (Table 4).
To further confirm the above results, multivariate logistic regression was also conducted and the results demonstrated that aetiology was correlated with root development of REPs with a regression coefficient of -2.687, OR 1.31, and 95% CI (0.007, 0.627) (P = 0.018) (Table 5).
Table 2
The influence of aetiology and preoperative diagnosis on root changes after REPs
Factors
|
Categories
|
Type I
n = 86
|
Type II
n = 9
|
Type III
n = 9
|
Type IV
n = 12
|
In total
n = 116
|
P
|
Aetiology
|
Dens Evaginatus
|
71 (86.6%)
|
8 (9.8%)
|
2 (2.4%)
|
1 (1.2%)
|
82 (70.7%)
|
<0.001***
|
|
Trauma
|
15 (44.1%)
|
1 (2.9%)
|
7 (20.6%)
|
11 (32.4%)
|
34 (29.3%)
|
Diagnosis
|
Symptomatic apical periodontitis
|
14 (77.8%)
|
0 (0.0%)
|
3 (16.7%)
|
1 (5.6%)
|
18 (15.5%)
|
0.608
|
|
Asymptomatic apical periodontitis
|
56 (72.7%)
|
6 (7.8%)
|
6 (7.8%)
|
9 (11.7%)
|
77 (66.4%)
|
|
|
Acute apical abscess
|
4(80.0%)
|
1(20.0%)
|
0(0.0%)
|
0(0.0%)
|
5 (4.3%)
|
|
|
Chronic apical abscess
|
12(75.0%)
|
2 (12.5%)
|
0 (0.0%)
|
2 (12.5%)
|
16 (13.8%)
|
|
* P<0.05, ** P<0.01, *** P<0.001,△Fisher's exact test
Table 3
The influence of age on root changes after REPs
Aetiology
|
Age
|
Type I
n = 86
|
Type II
n = 9
|
Type III
n = 9
|
Type IV
n = 12
|
In total
n = 116
|
p
|
Dens evaginatus
|
< 10.9
|
32 (84.2%)
|
4 (10.5%)
|
2 (5.3%)
|
0 (0.0%)
|
38 (46.3%)
|
0.413
|
≥ 10.9
|
39 (88.6%)
|
4 (9.1%)
|
0 (0.0%)
|
1 (2.3%)
|
44 (53.7%)
|
|
Trauma
|
< 8.9
|
8 (47.1%)
|
0 (0.0%)
|
3 (17.6%)
|
6 (35.3%)
|
17 (50.0%)
|
1.000
|
≥ 8.9
|
7 (41.2%)
|
1 (5.9%)
|
4 (23.5%)
|
5 (29.4%)
|
17 (50.0%)
|
|
* P<0.05, * * P<0.01, * * * P<0.001, △Fisher's exact test |
Table 4
The influence of preoperative root morphology on root changes after REPs
Aetiology
|
Root morphology
|
(mm)
|
Type I
|
Type II
|
Type III
|
Type IV
|
In total
n = 116
|
p
|
Dens evaginatus
|
Apical foramen size
|
<2.65
|
31 (81.6%)
|
4 (10.5%)
|
2 (5.3%)
|
1 (2.6%)
|
38 (46.3%)
|
0.319
|
≥ 2.65
|
40 (90.9%)
|
4 (9.1%)
|
0 (0.0%)
|
0 (0.0%)
|
44 (53.7%)
|
|
Root length
|
<11.50
|
35 (87.5%)
|
5 (12.5%)
|
0 (0.0%)
|
0 (0.0%)
|
40 (48.8%)
|
0.486
|
≥ 11.50
|
36 (85.7%)
|
3 (7.1%)
|
2 (4.8%)
|
1 (2.4%)
|
42 (51.2%)
|
|
Root thickness
|
<1.41
|
39 (81.3%)
|
7 (14.6%)
|
1 (2.1%)
|
1 (2.1%)
|
48 (58.5%)
|
0.182
|
≥ 1.41
|
32 (94.1%)
|
1 (2.9%)
|
1 (2.9%)
|
0 (0.0%)
|
34 (41.5%)
|
|
Trauma
|
Apical foramen size
|
<3.00
|
13 (52.0%)
|
1 (4.0%)
|
1 (1.0%)
|
10 (40.0%)
|
25 (73.5%)
|
0.001**
|
|
≥ 3.00
|
2 (22.2%)
|
0 (0.0%)
|
6 (66.7%)
|
1 (11.1%)
|
9(26.5%)
|
|
Root length
|
<12.90
|
8(42.1%)
|
1 (5.3%)
|
4 (21.1%)
|
6 (31.6%)
|
19 (55.9%)
|
1.000
|
|
≥ 12.90
|
7 (46.7%)
|
0 (0.0%)
|
3 (20.0%)
|
5 (33.3%
|
15 (44.1%)
|
|
Root thickness
|
<1.41
|
4 (40.0%)
|
0 (0.0%)
|
2 (20.0%)
|
4 (40.0%)
|
10 (29.4%)
|
0.921
|
|
≥ 1.41
|
11 (45.8%)
|
1 (4.2%)
|
5 (20.8%)
|
7 (63.6%)
|
(70.6%)
|
|
* P<0.05, * * P<0.01, * * * P<0.001, △Fisher's exact test |
Table 5
Multivariate analysis of root changes after REP
Factors
|
Regression coefficient
|
Standard error
|
OR 95% CI
|
p△
|
Aetiology
|
-2.687
|
1.133
|
(0.007, 0.627)
|
0.018*
|
* P<0.05, △multivariate logistic regression