Evaluation of Healing of Periapical Tissue in Permanent Incisors with Open Apices after Unintentional Extrusion of Mineral Trioxide Aggregate - A Retrospective Study.

AIM: The aim of the present study was to retrospectively assess the healing of periapical lesions in permanent central incisors with open apices after unintentional extrusion of mineral trioxide aggregate (MTA).
MATERIALS AND METHODS: The clinical and radiographic records of 75 maxillary permanent central teeth treated by MTA apexification were evaluated. Teeth with unintentionally extruded MTA formed the study group (Group 1, n = 28), whereas the teeth with no MTA extrusion formed the control group (Group 2, n = 47). For both the groups, the records were analyzed for a follow-up period of 3 years.
RESULTS: Complete healing (CH) was observed in 25 teeth in the study group, whereas all the teeth in the control group showed CH (P > 0.05). Within the study group, 6 teeth (21%) showed CH in the 6th month in Group 1, whereas in the control group, 34 teeth (72.3%) showed CH (P < 0.001). At the 1-year follow-up appointment, 19 teeth (67.8%) showed CH in Group 1, whereas 9 teeth (19.1%) showed the same result in Group 2 (P < 0.001). At the end of the 3-year follow-up period, it was noticed that in 21 (84%) teeth, extruded MTA remained unchanged, whereas it was reduced in 4 (16%) of them (P < 0.001).
CONCLUSION: Extrusion of MTA does not have a significant effect on the healing of the periapical lesion. However, it may lead to a delay in the healing of periapical healing. Patients should be informed about the complication and consequences of extruded MTA and should be kept on follow-up to observe periapical healing. Copyright:

INTRODUCTION

Pulpal involvement due to caries or trauma in a newly erupted permanent tooth can lead to loss of pulp vitality, thus directly affecting the development of root. It may result in short roots and thin walls, producing a higher risk of fracture, affecting the prognosis of the tooth.[1] Apexification was introduced to generate a calcific barrier in roots with open apices or for the sustained apical development of an incomplete root in teeth with necrotic pulp. Various materials are avaialble for this purpose, with calcium hydroxide being the most commonly used, but its multiple shortcomings such as multiple visits, increased chances of tooth fracture, and increased clinical cost led to the utilization of mineral trioxide aggregate (MTA) to fill the apical end.[2]

The various properties of MTA such as biocompatibility, sealing properties, and ability to promote periradicular regeneration make it a material of choice for apexification. Furthermore, MTA minimizes the sittings as apexification with MTA takes one or two visits, thus reducing the risk of vertical or oblique root fractures. During the apexification procedure, MTA is vertically condensed into the canal, leading to unintentional extrusion of the material into periapical tissues because of open apices.[3] The literature reports many case series with the extrusion of MTA during the apexification process. However, limited data is available on the status of periapical healing after the extrusion of MTA.

Thus, the main purpose of our study was to retrospectively assess the healing of periapical tissue in permanent incisors with open apices after unintentional extrusion of MTA.

MATERIALS AND METHODS

The present study was conducted by the department of pedodontics with patient consent and was approved by the institute's ethical committee. Records of 60 healthy patients (37 males and 23 females; age range 8–12 years) who underwent apexification for maxillary central incisor (n = 75) between 2015 and 2019 with MTA were evaluated. Patients with a follow-up period of 3 years were included in the study.

Inclusion criteria

Teeth with periapical pathology irrespective of the pathology size

Patient with 3 years of clinical and radiographic follow-up that were treated with MTA apexification procedure.

Exclusion criteria

Teeth with a root fracture or perforation.

Teeth were divided into two groups: Group 1 forms the study group (Group 1, n = 28), that consists of filled teeth with unintentional extrusion of MTA, which was confirmed by two observers, that is, an oral radiologist and a pedodontist. Teeth with no MTA extrusion formed the control group (Group 2, n = 47).

For every tooth, the clinical and radiographic records were evaluated from the beginning and at 3-month, 6-month, 1-year, 2-year, and 3-year follow-ups. The same two observers evaluated both the clinical and radiographic records and reached to the final decision by Halse and Molven[4] method.

According to the procedure, periapical healing was divided into groups as shown in Table 1.

Table 1

Periapical healing parameters in different groups

Periapical healing parameters	Clinically	Radiographically
CH	No signs and symptoms were observed	Normal-width periodontal ligament space
PH	No signs or symptoms	Reduction in lesion size
NH	Signs and symptoms of apical periodontitis present	No change, or an increase in the size of the lesion

CH: Complete healing, PH: Partial healing, NH: No healing

The amount of the MTA extruded unintentionally was radiographically observed in the follow-up periods and was recorded as either unchanged, reduced, almost absent, or absent.

Statistical analysis

The percentages of CH, PH, and NH within the study and control groups were compared. Their percentage was also calculated and analyzed within the same groups according to the follow-up periods. IN addition, the resorption of extruded MTA was recorded in every follow-up for each parameter of periapical healing. The Chi-square test was used for the statistical analysis (SPSS Inc., version 19.0, Chicago, IL, USA), and P ≤ 0.05 was considered statistically significant.

RESULTS

The results for the periapical healing of both are shown in Table 2. It was seen that after the 3-year follow-up, the difference in periapical healing between the study and control groups was not statistically significant (P > 0.05) for CH: it was observed in 25 teeth (89.2%) in the study group, whereas in the control group, it was seen in all the 47 teeth (100%). When the teeth with complete healing (CH) were considered during follow-up periods in both groups, 4 teeth showed CH (8.5%) in the 3rd month in Group 2, whereas none of the teeth in the group showed CH at the same session. In 6-month follow-up session, 6 teeth (21%) showed CH in the 6th month in Group 1, whereas in the control group, 34 teeth (72.3%) showed CH. The difference between them was statistically significant (P < 0.001). At the 1-year follow-up appointment, 19 teeth (67.8%) showed CH in Group 1, whereas 9 teeth (19.1%) showed the same result in Group 2 (P < 0.001). At the 2- and 3-year follow-up, the teeth that had shown CH in both groups were still in the same condition, and no signs of an apical inflammation were observed in these teeth. In Group 1, one tooth (3.5%) showed NH at the 2-year session, whereas two teeth (7.1%) were still in the condition of IH at the end of the 3rd year.

Table 2

Periapical healing results after each follow-up period for the different groups studied

Group	Periapical healing	3 months	6 months	1 year	2 years	3 years
Study group	CH (n=25)	-	6	19	-	-
	PH (n=2)	-	-	-	1	1
	NH (n=1)	-	-	-	1	-
Control group	CH (n=47)	4	34	9	-	-
	PH	-	-	-	-	-
	NH	-	-	-	-	-
P	<0.05		<0.00001	<0.00001

CH: Complete healing, PH: Partial healing, NH: No healing

Table 3 shows the amount of extruded MTA for the CH, IH, and NH groups for the study group. It was seen that in 21 (84%) teeth extruded, MTA remained unchanged, whereas it was reduced in 4 (16%) of them (P < 0.001).

Table 3

Changes in amount of extruded mineral trioxide aggregate for complete healing, partial healing, and no healing groups in the groups

MTA	Unchanged	Reduced	Almost absent	Absent	P
CH (n=25)	21	4	-	-	<0.05
PH (n=2)	-	2	-	-	-
NH (n=1)	1	-	-	-	-

MTA: Mineral trioxide aggregate, CH: Complete healing, PH: Partial healing, NH: No healing

Table 4 shows the amount of MTA as apices of teeth at different follow-ups. It was seen that after I year in teeth no change was seen in the extruded MTA in 68% of the teeth, whereas 32% of the teeth showed reduced extruded MTA; at the 2nd-year follow-up, MTA was unchanged in 8 (32%) teeth and was reduced in 17 (68%) teeth. On the other hand, at the end of the 3-year follow-up period, the amount of extruded MTA was observed to be significantly reduced in 21 teeth (84%) (P < 0.05), as shown in Table 4. In three teeth (12%), the extruded material was almost absent [Table 4], whereas the amount of extruded MTA was unchanged in two teeth (8%).

Table 4

Distribution of teeth according to unchanged, reduced, almost absent, and absent amounts of extruded mineral trioxide aggregate at the beginning and at 1-, 2-, and 3-year follow-ups

MTA	Unchanged	Reduced	Almost absent	Absent	P
Beginning	25	-	-	-	-
1 year	17	8	-	-	<0.05
2 years	8	17	-	<0.05
3 years	2	21	3	-	<0.05

MTA: Mineral trioxide aggregate

DISCUSSION

Immature teeth have a wide, apical opening, thus achieving a favorable apical seal in these teeth is difficult. It necessitates the use of a large amount of filling material that may project into the periapical area, triggering inflammatory reactions. The absence of an apical seat or step may also result in the squeezing material projecting apically. Special placement techniques have also been suggested for MTA delivery to minimize the projection of the material. Despite advances in dentistry, sometimes apical projection of the material occurs while filling the canal from an orthograde direction.[5] This may result in various complications such as delayed healing of periapical infection, severe inflammation, necrosis of the bone tissue, or foreign body reaction.[6] Several studies have documented the different results regarding the healing of lesion and resorption of MTA. It ranges from no healing to complete healing of the lesion; however, the data on the status of healing and resorption at different follow-ups are still lacking.

MTA offers various benefits because of its superior physiochemical and bioactive properties. It helps form an effective seal against dentin and cementum, thus helping in root-end induction and helping in perforation repair. It also enhances the biologic repair and regeneration of the periodontal ligament (PDL).[7] Due to the above-mentioned properties, the use of MTA as an obturation material provides long-term benefits that enhance the prognosis and retention of the natural dentition. El-Meligy and Avery in their study compared MTA with calcium hydroxide (Ca[OH]2) clinically and radiographically as materials used to induce root-end closure in necrotic permanent teeth with immature apices (apexification).[8] They found that MTA is a better material than calcium hydroxide and can be used as a replacement material in teeth with immature apices. Similar results were shown by Damle et al.[9] and Pradhan et al.[10] in their studies.

Thus, in the present study, records of patients with open apices and periapical lesion in whom unintentional extrusion of MTA occurred while apexification was evaluated at different periods. Mente et al.[11] in their study showed the healing rate of 85% in MTA-treated teeth with periapical radiolucencies as compared to 96% of teeth without preoperative periapical radiolucencies, which was comparable to the healed lesion of 100% [Table 2] in our study in Group 2.

Chang et al.[5] in their case series concluded that direct contact with MTA had no harmful effects on the healing of the periapical tissues. All the three cases attained complete healing by 36–54 months. The results were in accordance with our study, whereby at the end of 1 year, 89% of cases have achieved complete healing, thus showing that extruded MTA does not affect the healing of the periapical tissue. The present study results were also in agreement with Azim et al.,[12] who reported that the average time required for a periapical lesion to heal was 11.78 months [Table 2], which was similar to our finding. Our study also showed that extruded MTA does not affect the healing.

Tahan et al.[13] in their case series reported that extruded MTA through the periradicular lesion associated with necrotic pulps shows no complications and teeth are free of symptoms throughout the healing period, which was similar to our results, in which only one (3%) [Table 2] tooth showed no healing. In their case series, complete resorption of the filling material did not occur, although the periradicular and periextrusion radiolucency disappeared after 12-month recall, which was similar to our results which showed that although the marked reduction in MTA was seen at the end of 3-year follow-up [Table 4], it was not wholly absent. Similar results were observed by the case series reported by Comin Chiaramonti and Cavalleri.[14] They found that at follow-up, the tooth was asymptomatic after MTA extrusion in molar and at repair of the lesion was evident radiographically. Our results were also in accordance with the study performed by Demiriz et al.,[15] who showed that MTA extrusion was reduced in 85% and was almost absent in 10% teeth compared with 84% and 12%, respectively, in our study.

The present study's findings showed that the extrusion of MTA does not have a significant effect on the healing of the periapical lesion. However, it may lead to a delay in the healing of periapical healing. Patients should be informed about the complication and consequences of extruded MTA and should be kept on follow up to observe periapical healing.

CONCLUSION

MTA has proved to be superior to other materials due to its biochemical and physical nature. Its root induction property effectively forms a seal against dentin and cementum, helping in perforation repair. It also promotes the biologic repair and regeneration of the periodontal ligament. Our study showed that extrusion of MTA in periapical lesion does not have major effect on the healing of the peri-radicular tissue. However, it takes times for the complete resorption of MTA to occur and hence follow-up should be kept to observe the healing and resorption of MTA.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.