Keywords
dental - digital periapical radiograph - apical periodontitis - permanent coronal
restoration - root canal treatment
Introduction
The importance of natural teeth preservation cannot be overemphasized. In fact, when
given options are extraction and root canal treatment, endodontic treatment should
be treatment of choice as it can provide the best health and cosmetic result.[1] The intention of nonsurgical root canal treatment is to provide conditions for the
healing of periapical tissues by eliminating infection from the root canal system
and to keep the tooth's function in the oral environment.[2]
[3]
Cross-sectional studies conducted in different European, American, and Asian populations
reported that endodontically treated teeth are prevalent among adults, ranging from
1.5 to 21% out of all examined teeth.[4]
[5]
[6]
[7] Posttreatment disease, a phrase suggested by Friedman, describes the persistence
of apical periodontitis (AP) in endodontically treated teeth.[8] Studies conducted at dental schools, where endodontic treatment was performed or
supervised by an endodontic specialist reported a success rate to be more than 90%.[8]
[9]
[10]
[11] On the other hand, the studies reflecting a more realistic outcome of endodontic
treatments in the general populations reported the prevalence of AP in endodontically
treated teeth to range from 25 to more than 65%.[4]
[12] Therefore, posttreatment AP constitutes a significant health problem in many populations
and attempts have been made to identify prognostic factors for this disease. Yet,
further investigations are required to improve the outcomes of root canal treatment
and benefits related to the oral health of the population.
Postendodontic restoration of the tooth crown is an essential factor in the reinstitution
of the tooth function and the prevention of coronal leakage. Studies have attempted
to disclose the role of the coronal restoration type and quality in outcome of root
canal treatment. A recent study reported that neither the type nor the material of
the restoration was significant for periapical status of endodontically treated teeth
if the quality of the restoration was acceptable.[13] Conversely, a study conducted in Sweden revealed that besides the quality of the
root filling, restoration type may also be predictive of AP in root-filled teeth.[14]
In vivo studies investigating the impact of coronal restoration and root fillings on periapical
status reported inconsistent results. Ray and Trope, and Kirkevang et al reported
that quality of coronal restorations had a significantly greater impact on periapical
status than the quality of root canal filling.[15]
[16] Several studies identified both the coronal restoration and root canal treatment
quality as a predictor of periapical status,[17]
[18]
[19] while some studies implicated a lesser impact of the coronal restoration quality
on the outcome of the endodontic treatment in comparison to the quality of root canal
treatment.[20]
[21]
The hypothesis for the present study was that the periapical condition of endodontically
treated teeth significantly varies with regard to the type and quality of permanent
coronal restorations. This study aimed to explore posttreatment AP in endodontically
treated teeth through a multivariate approach and to analyze the relative importance
of type and quality of coronal restoration as predictors of periapical disease.
Materials and Methods
This study protocol was approved by the Ethical Committee of the Clinical Hospital
Center Rijeka (003-05/13-01/03). Study sample was drawn within 2 years from the 1,072
consecutive patients older than 18 years, who attended the Dental Clinic of the Clinical
Hospital Center Rijeka, Croatia for the first time.
Participants were excluded if they declined to participate in the study, had seven
or less remaining teeth, received endodontic therapy within previous 2 years, and
were unwilling or unable to attend the radiographic diagnostics. To be enrolled in
the survey, the patient's chart had to comprise panoramic radiograph. After applying
these criteria, the sample consisted of 597 participants who agreed to take part by
signing an informed consent. The study was conducted in accordance with the World
Medical Association Declaration of Helsinki principles.
Endodontically treated teeth were identified from panoramic radiographs. Teeth were
recorded as endodontically treated if radiopaque material was visible in pulp chamber
and/or root canal(s). Teeth with temporary or missing restorations were excluded from
further analysis. Digital periapical radiographs of all permanently restored endodontically
treated teeth were taken with paralleling technique using X-ray unit (Trophy Elitys;
Trophy Radiologie, Marne-la-Vallee, France) and intraoral sensor (One; Owandy Radiology,
Roslyn, New York, United States). The applied exposure parameters were 60 kV, 7 mA,
and 0.25 seconds. Images were analyzed on a 19-inch liquid crystal monitor (P1914S;
Dell, Austin, Texas, United States; resolution: 1.280 × 1.024 32-bit color; graphic
card: HD Graphic; Intel, Santa Clara, California, United States). For each tooth,
the periapical status, root filling quality, intracanal post and separated file presence,
marginal bone loss, and quality and type of coronal restoration were recorded. All
criteria are listed in [Table 1].
Table 1
Variables scored in root-filled teeth
|
Variables
|
Codes
|
|
Tooth type
|
0 = Anterior
1 = Premolar
2 = Molar
|
|
Arch type
|
0 = Maxilla
1 = Mandible
|
|
Apical periodontitis[22]
|
0 = Absent (PAI score = 1, 2)
|
|
1 = Present (PAI score = 3, 4, 5)
|
|
Length of root filling[5]
|
0 = Adequate (ending 0–2 mm short of the radiographic apex)
|
|
1 = Short (ending more than 2 mm from the radiographic apex)
|
|
2 = Long (extruding beyond the radiographic apex)
|
|
Density of root filling[5]
|
0 = Adequate (uniform radiodensity and adaptation of the filling to the root canal
walls)
|
|
1 = Inadequate (visible canal space laterally along the filling or voids within the
filling mass, or identifiable untreated canal)
|
|
Quality of root filling (combined criteria for length and density of root filling)[a]
|
0 = Adequate (ending 0–2 mm from radiographic apex, no voids present)
|
|
1 = Inadequate (ending > 2 mm short of, or extending beyond the radiographic apex,
presence of voids, or untreated canal)
|
|
Intracanal post[17]
|
0 = Absent (absence of a metal or fiber post in the root canal)
|
|
1 = Present (presence of a metal or fiber post in the root canal)
|
|
Separated file
|
0 = Absent
|
|
1 = Present
|
|
Marginal bone loss[13]
|
0 = No marginal bone loss (≤1/3 of the root length)
|
|
1 = Marginal bone loss (>1/3 of the root length)
|
|
Type of coronal restoration[14]
|
0 = 1–3 surfaces amalgam
|
|
1 = 4–5 surfaces amalgam
|
|
2 = 1–3 surfaces composite
|
|
3 = 4–5 surface composite
|
|
4 = Inlay
|
|
5 = Crown
|
|
Quality of coronal restoration (clinically and radiographically)[14]
[23]
[24]
|
0 = Adequate (no defective restoration margin, no signs of recurrent caries)
|
|
1 = Inadequate (defective restoration margin and/or presence of recurrent caries)
|
|
Combined quality of root filling and coronal restoration[a]
|
0 = Adequate root filling/adequate coronal restoration
|
|
1 = Adequate root filling/inadequate coronal restoration
|
|
2 = Inadequate root filling/adequate coronal restoration
|
|
3 = Inadequate root filling/inadequate coronal restoration
|
Abbreviation: PAI, periapical index.
a Variables used only in univariate analysis.
Analysis of the endodontic variables and marginal bone loss was accomplished using
periapical radiographs. The AP presence was assessed utilizing the periapical index
(PAI) system.[22] Visual references for the full-scale PAI were applied to determine the periapical
condition of each tooth. In multirooted teeth, the highest PAI value of all roots
was used to define the periapical status. PAI scores were dichotomized, and AP was
recorded as absent (PAI scores 1 and 2) or present (PAI scores 3, 4, and 5; [Fig. 1]). The root filling quality was scored with respect to length and density according
to previously reported criteria.[5] Marginal bone loss was estimated as less or more than one-third of the root length.[13]
Fig. 1 Periapical radiographs of endodontically treated teeth originating from investigated
material representing each of the five periapical index (PAI) scores. Absence of apical
periodontitis: PAI = 1 and PAI = 2. Presence of apical periodontitis: PAI = 3, PAI = 4,
and PAI = 5.
The quality of coronal restoration was assessed clinically and radiographically with
respect to marginal integrity of restoration and recurrent caries presence. Modified
U.S. Public Health Service/Ryge criteria for marginal integrity and recurrent caries
were used for the clinical evaluation of coronal restoration as reported by Merdad
et al.[23] Marginal integrity was radiographically assessed as adequate (radiographically sealed)
or inadequate (signs of open margins or overhangs) according to previously described
criteria.[24] Recurrent caries was recorded as absent or present in case of clearly visible decrease
in mineral content of a proximal tooth surface contiguous with a restoration.[14]
All data were recorded by one observer. Observer's agreement to PAI scores from 100
reference radiographs resulted in Cohen's kappa value of 0.70.[22] Calibrations for assessment of dental caries, coronal restoration quality, quality
of root canal filing, and marginal bone loss were performed according to the World
Health Organization recommendations.[25] Intraobserver agreement was analyzed by double scoring of the 30 randomly selected
study participants' clinical and radiographic surveys. Kappa values for clinical and
radiographic diagnosis of recurrent caries were 0.85 and 0.92, respectively, while
clinical and radiographic assessment of marginal integrity yielded kappa values of
0.81 and 0.85, respectively. Intraobserver kappa values were 0.75 for PAI, 0.80 and
0.85 for length and density of the root canal filling, and 0.89 for marginal bone
loss.
Statistical Analysis
Statistical calculations were performed using MedCalc statistical software (MedCalc
Software Ltd., Belgium) at level of statistical significance p < 0.05. Lilliefors' test was used to test data for distribution normality. As the
data did not distribute normally, median and interquartile range were used to report
central tendency and dispersion. Mann–Whitney's U test was used to investigate the differences between the groups regarding the continuous
variables. Chi-square tests were used to analyze the significant variations in periapical
status, quality of root canal filling, and quality of coronal restoration according
to the tooth type. Univariate logistic regression was applied to explore the effect
of diverse variables on periapical status. The variables with significant associations
in univariate model were included in multivariate logistic regression analysis to
identify significant predictors of the outcome variable. The outcome variable was
set as the presence versus absence of AP in the tooth.
Results
The majority of sample consisted of women (68.2%). The average age of participant
was 34 years (interquartile range 24–46). No significant differences between male
and female participants were determined regarding age (Mann–Whitney's U test; p = 0.534), median number of root-filled teeth (Mann–Whitney's U test; p = 0.387), or median number of root-filled teeth with AP (Mann–Whitney's U test; p = 0.181). Root-filled teeth were found in 448 (75.0%) participants, while 334 (54.3%)
participants had one or more root-filled teeth with radiological signs of AP. No significant
difference was demonstrated between male and female participants considering the prevalence
of endodontic treatment (χ2 = 0.15; p = 0.697) and posttreatment AP (χ2 = 1.27; p = 0.260).
Of the 1,350 endodontically treated teeth investigated in the present study, the distribution
included 386 (28.6%) anterior, 430 (31.9%) premolar, and 534 molar teeth (39.6%).
AP was present in 634 teeth (47%). Most of examined teeth had inadequate quality of
root filling (67.6%) and coronal restoration (60.1%).
Significant differences in the root filling quality (χ2 = 41.83; p < 0.001) and the coronal restoration quality (χ2 = 15.25; p < 0.001) regarding the tooth type were observed. Molars had significantly higher
proportion of inadequate root fillings than anterior (76.6 vs. 56.6%; p < 0.001) and premolar teeth (76.6 vs. 66.3%; p < 0.001). Also, poor quality of coronal restoration was significantly more frequent
in molar than anterior (66.5 vs. 57.3%; p < 0.005) and premolar teeth (66.5 vs. 54.9%; p < 0.001). Furthermore, the periapical status significantly differed regarding the
tooth type (χ2 = 64.29; p < 0.001). Only 215 molars (40.3%) were designated as periapically healthy, while
255 (66.1%) anterior and 246 (57.2%) premolar teeth had no radiological signs of AP.
When compared with anterior and premolar teeth, molars had significantly higher proportion
of periapical disease (both p < 0.001; [Table 2]).
Table 2
Distribution of teeth according to the tooth type with differences in the quality
of the root filling, quality of coronal restoration, and periapical status
|
Tooth type
|
No. of teeth
|
Quality of root filling
|
|
Quality of coronal restorations
|
|
Periapical status
|
|
|
Adequate
N (%)
|
Inadequate
N (%)
|
Adequate
N (%)
|
Inadequate
N (%)
|
AP absence
|
AP presence
|
|
Anterior
|
386
|
168 (43.5)
|
218 (56.5)
|
[b]
|
165 (42.7)
|
221 (57.3)
|
[c]
|
255 (66.1)
|
131 (33.9)
|
[b]
|
|
Premolar
|
430
|
145 (33.7)
|
285 (66.3)
|
[b]
|
194 (45.1)
|
236 (54.9)
|
[c]
|
246 (57.2)
|
184 (42.8)
|
[b]
|
|
Molar
|
534
|
125 (23.4)
|
409 (76.6)
|
[b]
|
179 (33.5)
|
355 (66.5)
|
[b]
|
215 (40.3)
|
319 (59.7)
|
[b]
|
|
Total
|
1350
|
438 (32.4)
|
912 (67.6)
|
|
538 (39.9)
|
812 (60.1)
|
|
716 (53.0)
|
634 (47.0)
|
|
|
Statistics
|
|
χ2 = 41.83
p < 0.001[a]
|
|
χ2 = 15.25
p < 0.001[a]
|
|
χ2 = 64.29
p < 0.001[a]
|
|
Abbreviation: AP, apical periodontitis.
a Statistically significant (chi-square test).
b Significant difference versus both other tooth types.
c Significant difference versus molars.
[Table 3] demonstrates the distribution of root-filled teeth presenting with and without AP
according to independent variables and their associations with periapical status.
An increased risk for AP presence was demonstrated for premolars (odds ratio [OR] = 1.46;
95% confidence interval [CI]: 1.10–1.94; p = 0.010) and molars (OR = 2.89; 95% CI: 2.20–3.79; p < 0.001). Mandibular teeth were more frequently affected than maxillary teeth constituting
56.1% of AP findings with an increased odds of AP presence (OR = 1.73; 95% CI: 1.30–2.17;
p < 0.001). Significant variations in periapical status regarding quality of root filling
were found. Based on combined criteria for length and density of the root canal filing,
the overall quality of the root canal filling was rated as adequate in only 438 (32.4%)
of the examined teeth. Of these teeth, 385 (87.9%) had no radiologic signs of AP.
AP was the least frequent in teeth with adequate length of root canal filing (17.1%)
compared with teeth with short length of root canal filling (69.8%) and teeth with
root canal filling extended beyond the apex (40.0%). An increased risk for AP was
demonstrated in underfilled (OR = 11.19; 95% CI: 8.51–17.71; p < 0.001) and overfilled teeth (OR = 3.23; 95% CI: 1.93–5.39; p < 0.001). It was observed that 56.7% of teeth had inadequate density of root filling
with AP prevalence of 68%. This group demonstrated an increased risk for AP presence
(OR = 8.86; 95% CI: 6.90–11.44; p < 0.001). Intracanal post was detected in 276 teeth (20.4%). The proportion of AP
in teeth restored with intracanal post was 52.9%, demonstrating higher odds for AP
than in teeth without the post (OR = 1.35; 95% CI: 1.03–1.76; p = 0.030).
Table 3
Univariate logistic regression for associations of diverse variables and apical periodontitis
in root-filled teeth
|
Variables
|
Total
|
AP absent
N (%)
|
AP present
N (%)
|
OR
|
95% CI
|
p-Value
|
|
Tooth type
|
|
Anterior
|
386
|
255 (66.1)
|
131 (33.9)
|
1
|
Reference
|
|
|
Premolar
|
430
|
246 (57.2)
|
184 (42.8)
|
1.46
|
1.10–1.94
|
0.010[a]
|
|
Molar
|
534
|
215 (40.3)
|
319 (59.7)
|
2.89
|
2.20–3.79
|
<0.001[a]
|
|
Arch type
|
|
Maxilla
|
906
|
521 (57.5)
|
385 (42.5)
|
1
|
Reference
|
|
|
Mandible
|
444
|
195 (43.9)
|
249 (56.1)
|
1.73
|
1.3–2.17
|
<0.001[a]
|
|
Length of root filling
|
|
Adequate
|
543
|
450 (82.9)
|
93 (17.1)
|
1
|
Reference
|
|
|
Short
|
732
|
221 (30.2)
|
511 (69.8)
|
11.19
|
8.51–14.71
|
<0.001[a]
|
|
Long
|
75
|
45 (60.0)
|
30 (40.0)
|
3.23
|
1.93–5.39
|
<0.001[a]
|
|
Density of root filling
|
|
Adequate
|
584
|
471 (80.7)
|
113 (19.3)
|
1
|
Reference
|
|
|
Inadequate
|
766
|
245 (32.0)
|
521 (68.0)
|
8.86
|
6.90–11.44
|
<0.001[a]
|
|
Quality of root filling
|
|
Adequate
|
438
|
385 (87.9)
|
53 (12.1)
|
1
|
Reference
|
|
|
Inadequate
|
912
|
331 (36.3)
|
581 (63.7)
|
12.75
|
9.28–17.51
|
<0.001[a]
|
|
Intracanal post
|
|
Absent
|
1,074
|
586 (54.6)
|
488 (45.4)
|
1
|
Reference
|
|
|
Present
|
276
|
130 (47.1)
|
146 (52.9)
|
1.35
|
1.03–1.76
|
0.030[a]
|
|
Separated file
|
|
Absent
|
1,311
|
701 (53.5)
|
610 (46.5)
|
1
|
Reference
|
|
|
Present
|
39
|
15 (38.5)
|
24 (61.5)
|
1.84
|
0.96–3.54
|
0.068
|
|
Marginal bone loss
|
|
≤1/3 root length
|
963
|
506 (52.5)
|
457 (47.5)
|
1
|
Reference
|
|
|
> 1/3 root length
|
387
|
210 (54.3)
|
177 (45.7)
|
0.933
|
0.74–1.18
|
0.567
|
|
Type of coronal restoration
|
|
1–3 surface amalgam
|
48
|
21 (43.8)
|
27 (56.2)
|
1
|
Reference
|
|
|
4–5 surface amalgam
|
67
|
29 (43.3)
|
38 (56.7)
|
1.02
|
0.48–2.15
|
0.960
|
|
1–3 surface composite
|
472
|
259 (54.9)
|
213 (45.1)
|
0.64
|
0.35–1.16
|
0.143
|
|
4–5 surface composite
|
312
|
171 (54.8)
|
141 (45.2)
|
0.64
|
0.35–1.18
|
0.155
|
|
Inlay
|
13
|
8 (61.5)
|
5 (38.5)
|
0.49
|
0.14–1.70
|
0.260
|
|
Crown
|
438
|
228 (52.1)
|
210 (47.9)
|
0.72
|
0.39–1.31
|
0.276
|
|
Quality of coronal restoration
|
|
Adequate
|
538
|
330 (61.3)
|
208 (38.66)
|
1
|
Reference
|
|
|
Inadequate
|
812
|
386 (47.5)
|
426 (52.5)
|
1.75
|
1.40–2.19
|
<0.001[a]
|
Abbreviations: AP, apical periodontitis; CI, confidence interval; OR, odds ratio.
a Statistically significant.
Considering high prevalence of teeth with inadequate quality of coronal restoration,
a significant association with periapical disease presence was found (OR = 1.75; 95%
CI: 1.40–2.19; p < 0.001; [Table 3]). Variables separated file, marginal bone loss, or type of coronal restoration was
not significantly associated with the presence of periapical disease.
Association of outcome variable (AP) and combined data for root filling quality and
coronal restoration quality were analyzed by means of univariate logistic regression
([Table 4]). Teeth with both adequate quality of root filling and restoration exhibited the
lowest prevalence of AP (12.2%) and were used as a reference category. In case of
adequate root filling and inadequate restoration, AP was observed in 12.2% of teeth;
however, the risk for AP presence was not increased in this group. Conversely, combination
of inadequate quality of root filling and adequate quality of restoration was significantly
associated with AP (OR = 10.35; 95% CI: 6.59–16.24; p < 0.001). The highest association with AP presence was observed in case of inadequate
quality of both analyzed parameters (OR = 13.76; 95% CI: 9.02–21.00; p < 0.001). The highest prevalence of AP of 65.6% occurred in this group ([Table 4]).
Table 4
Univariate logistic regression for association of combined quality of root canal filling
and coronal restoration with apical periodontitis
|
Covariate
|
No. of teeth
|
AP absence
N (%)
|
AP presence
N (%)
|
OR
|
95% CI
|
p-Value
|
|
Adequate root filling/adequate restoration
|
238
|
209 (87.8)
|
29 (12.2)
|
1
|
Reference
|
|
|
Adequate root filling/inadequate restoration
|
196
|
172 (87.8)
|
24 (12.2)
|
1.01
|
0.57–1.79
|
0.985
|
|
Inadequate root filling/adequate restoration
|
302
|
124 (41.1)
|
178 (58.9)
|
10.35
|
6.59–16.24
|
<0.001[a]
|
|
Inadequate root filling/inadequate restoration
|
614
|
211 (34.4)
|
403 (65.6)
|
13.77
|
9.02–21.00
|
<0.001[a]
|
Abbreviations: AP, apical periodontitis; CI, confidence interval; OR, odds ratio.
a Statistically significant.
The results of multivariate logistic regression analysis are presented in [Table 5]. Only variables with significant associations in univariate analysis (except overall
quality of root filling) were included in multivariate model. Five variables maintained
significant associations with the AP presence: tooth type, dental arch, length and
density of the root canal filling, and intracanal post. Regarding the tooth type and
dental arch, the OR for AP presence was 2.15 times higher in molars (OR = 2.15; 95%
CI: 1.51–3.06; p < 0.001) than in anterior teeth, while compared with maxillary dental arch, teeth
positioned in mandible had 1.49 times increased odds of AP presence (OR = 1.49; 95%
CI: 1.11–1.99; p = 0.007). When compared with teeth with adequate length of the root filling, the
OR for the presence of AP was 4.08 times higher if the length of the root filling
was short (OR = 4.08; 95% CI: 2.93–5.69; p < 0.001) and 2.99 times higher in the case of the overfilling (OR = 2.99; 95% CI:
1.71–5.24; p = 0.001). Teeth with inadequate density of root filling had 4.14 times increased
odds of AP presence (OR = 4.14; 95% CI: 3.01–5.69; p < 0.001) than those with adequate density. The presence of intracanal post increased
the risk for tooth having AP 1.57 times (OR = 1.57; 95% CI: 1.12–2.22; p = 0.009; [Table 5]).
Table 5
Multivariate logistic regression for association of diverse variables and apical periodontitis
in root-filled teeth
|
Variables
|
No. of teeth
|
Odds ratio
|
95% CI
|
p-Value
|
|
Tooth type
|
|
Anterior
|
386
|
1
|
|
|
|
Premolar
|
430
|
1.28
|
0.91–1.81
|
0.162
|
|
Molar
|
534
|
2.15
|
1.51–3.06
|
<0.001[a]
|
|
Arch type
|
|
Maxilla
|
906
|
1
|
|
|
|
Mandible
|
444
|
1.49
|
1.11–1.99
|
0.007[a]
|
|
Length of root filling
|
|
Adequate
|
543
|
1
|
|
|
|
Short
|
732
|
4.08
|
2.93–5.69
|
<0.001[a]
|
|
Long
|
75
|
2.99
|
1.71–5.24
|
<0.001[a]
|
|
Density of root filling
|
|
Adequate
|
584
|
1
|
|
|
|
Inadequate
|
766
|
4.14
|
3.01–5.69
|
<0.001[a]
|
|
Intracanal post
|
|
Absent
|
1074
|
1
|
|
|
|
Present
|
276
|
1.57
|
1.12–2.22
|
0.009[a]
|
|
Quality of coronal restoration
|
|
Adequate
|
538
|
1
|
|
|
|
Inadequate
|
812
|
1.29
|
0.98–1.70
|
0.070
|
Abbreviations: AP, apical periodontitis; CI, confidence interval; OR, odds ratio.
a Statistically significant.
Discussion
The prevalence of posttreatment AP in endodontically treated teeth in the current
study was 47%, which was rather high but comparable to the range reported by other
cross-sectional studies conducted among different populations.[4]
[5]
[6]
[7]
[17] Approximately 68% of teeth had poor quality of root filling, while 60% had substandard
quality of coronal restoration. Molar teeth yielded the highest prevalence of AP (59.7%).
This is not surprising since almost 77% of them had inadequate root canal filling
quality, and the quality of coronal restoration was categorized as substandard in
more than 66% molars. Difficulties encountered in treatment of molar teeth include
inherent anatomical complexity and distal position. These limitations may be the explanations
why most molars have substandard quality of root filling, yet the reasons for poor
quality of coronal restorations remain unclear. Our results are consistent with most
of the other studies reporting the highest prevalence of AP in endodontically treated
molars.[5]
[6]
[17]
Most of the analyzed teeth had inadequate quality of root filling (63.7%). As expected,
teeth with both adequate length and density of root filling exhibited significantly
less posttreatment AP than teeth with inadequate features of root filling. Interestingly,
while underfilled teeth were most frequently affected with AP constituting almost
70% of the findings, teeth with root filling extending beyond the apex had significantly
better periapical condition with AP prevalence of 40%. A recent systematic analysis
reported a significantly increased risk of nonhealing outcome in case of endodontic
material extrusion.[26] Others report that sealer extrusion did not compromise the success of endodontic
treatment.[27]
[28] Given that currently used root filling materials vary regarding biocompatibility,
physical and chemical properties, further studies are necessary to clarify this issue.
Instrument separation is an unpleasant complication occurring during the preparation
of root canal and may affect the endodontic treatment outcome.[29] The present study revealed no significant difference in the periapical status regarding
the presence of separated file. Treatment outcome is likely to be influenced by the
stage of canal preparation and control of microbial infection when instrument separation
occurs. Instrument fracture occurring in early stages of canal preparation would compromise
disinfection and obturation of the root canal and significantly influence tooth prognosis.[30] However, it seems that tooth prognosis is not significantly affected by instrument
separation in case the treatment is performed under high technical standards.[31]
A study evaluating periodontal status of teeth indicated for undergoing endodontic
treatment reported the rate of the periodontally compromised teeth to be almost 20%.[32] The present results demonstrated marginal bone loss of more than one-third of the
root length in almost 29% of teeth. Though previous studies reported an association
between marginal bone level and AP,[13]
[33] our results did not demonstrate any significant variations in periapical condition
regarding the marginal bone loss.
Combined data for the root filling and coronal restoration quality were analyzed.
Same prevalence of AP was observed in teeth with both adequate root filling and adequate
coronal restoration, and in teeth with adequate root filling and inadequate restoration
(both 12.2%). Significantly, worse outcome was observed in case of inadequate root
filling quality, regardless of the coronal restoration quality. Congruent with previous
investigation, our results may imply that the root filling quality may be more significant
prognostic variable for posttreatment AP than quality of coronal restoration.[34]
In the present study, the type of coronal restoration was not correlated with AP presence.
The quality of coronal restoration demonstrated significant association with periapical
status in univariate analysis; however, this association did not remain significant
when multivariate analysis was applied. This may be due to the influence of other
significant variables in the multivariate logistic regression model. Therefore, the
hypothesis that the periapical status of endodontically treated teeth significantly
varies with regard to the type and quality of permanent coronal restorations could
not be verified. As in previous studies, the present results confirmed the strong
association between the technical quality of root filling and AP presence.[13]
[14]
[17] The mandibular teeth had a higher risk for AP, and molars likewise presented significantly
increased risk for AP presence. A significant association between the intracanal post
presence and periapical disease was observed. It was argued that this may be due to
root canal contamination during restoration procedure.[8] Other studies reported no difference between teeth with or without a post.[17]
[18]
[19]
Considering the variety of factors that can influence the endodontic treatment failure,
posttreatment AP should be investigated through multivariate models as they reflect
better approximation to reality and allow for estimation of the relative importance
of each predictor variable. However, it should be kept in mind that due to cross-sectional
study design, there are variables that could not have been controlled and yet might
have impacted the results. Endodontic treatment of teeth is a highly demanding procedure,
and besides the obturation quality, its success also depends on mechanical instrumentation
and disinfection effectiveness. Personal skills of operator are likely to influence
the outcome of root canal treatment. This survey included participants who attended
the dental clinic for the first time. According to the data reported by participants,
general practitioners were providers of endodontic treatment in teeth included in
the present study. However, no information regarding the endodontic treatment protocol
were available. Time of postendodontic coronal restoration placement and proper aseptic
technique application are also aspects that could not be assessed in this study.
Only participants who had endodontic treatment performed more than 2 years ago were
recruited in the present study. A comprehensive study investigating factors affecting
nonsurgical root canal treatment reported that more than 95% of periapical lesions
completely healed within 2 years following root canal treatment.[35] Therefore, recruiting the participants who had endodontic treatment performed more
than 2 years prior to this study seemed a reasonable time interval to avoid possible
overestimation of AP presence in case of the periapical radiolucency that represents
a stage of healing.
The limitations of conventional radiography, such as periapical and panoramic radiographs,
are well established.[36]
[37] The main disadvantages are a two-dimensional nature of generated image with anatomical
noise, masking the area of interest, and geometric distortion.[37] Due to high sensitivity in detection of periapical lesion and ability to provide
high detail of the root canal system, the use of small field of views cone beam computed
tomography (CBCT) in diagnosis and management of endodontic disease is increasing.
When compared with CBCT, both panoramic and periapical radiographs correctly identify
AP only in advanced stages, and therefore, the prevalence of AP may be underestimated.[38] However, the potential benefits of CBCT must be balanced with comparatively higher
levels of risk from radiation exposure. The presence of metallic restorations (e.g.,
amalgam restorations, metal posts, crowns, and implants) or even gutta-percha can
cause significant radiographic artifact, sufficient to compromise details of root
canal anatomy and relevant pathosis.[37] Furthermore, it was demonstrated that the diagnostic accuracy of CBCT in detection
of AP was high for non-root-filled teeth, while the diagnosis of AP on root-filled
teeth was less accurate.[39] Despite the excellent accuracy of CBCT in AP diagnostics, it is still recommended
to limit its use in endodontics on cases when conventional radiographic techniques
do not provide sufficient information for confident diagnosis and treatment planning.[40] Considering the advantages and limitations inherent in each technique, and the cross-sectional
design of the present study involving a large number of participants, the authors
opted for periapical radiographs for AP diagnosis.
Conclusion
Within the limitations of the present survey, it may be concluded that even though
the coronal restoration quality is important in outcome of endodontic treatment, it
seems that it is not a decisive factor. Multivariate analysis revealed that molars,
mandibular teeth, short and long root fillings, inadequate density of root filling,
and intracanal post are most important predictors for posttreatment periapical disease.
