Evaluate the Efficacy of Endodontic Microsurgery on Teeth Having Undeveloped Root Apex Failed in Non-surgical Treatment with Periapical Inflammation

doi:10.21203/rs.3.rs-2634335/v1

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Evaluate the Efficacy of Endodontic Microsurgery on Teeth Having Undeveloped Root Apex Failed in Non-surgical Treatment with Periapical Inflammation

https://doi.org/10.21203/rs.3.rs-2634335/v1

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published 22 Jun, 2023

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Background: To evaluate the efficacy of endodontic microsurgery on teeth with undeveloped root apex and periapical inflammation caused by an abnormal central cusp fracture due to failed nonsurgical treatment.

Methodology: We performed endodontic microsurgery on 80 teeth in 78 patients with undeveloped root apex and periapical inflammation caused by an abnormal central cusp fracture due to failed nonsurgical treatment. All patients were clinically and radiologically examined 1 year after surgery, and the data were statistically analyzed using the SPSS 27.0 software package.

Results: Of 80 teeth in 78 patients, periapical lesions disappeared in 77 teeth at the 1-year postoperative follow-up, with a success rate of approximately 96.3% (77/80). Sex, age, extent of periapical lesions, and the presence of the sinus tractdid not affect the efficacy of endodontic microsurgery. The differences between groups were not statistically significant (P > 0.05).

Conclusions: On failure of nonsurgical treatment in teeth with undeveloped root apexand periapical inflammation caused by an abnormal central cusp fracture, endodontic microsurgery may be a good clinical treatment option.

abnormal central cusp

periapical inflammation

unclosed apical foramen

endodontic microsurgery

Abnormal central cusps mostly occur in mandibular second premolars, with a prevalence of approximately 2% in Asian populations and of 1.29–3.6%^[1]in Chinese populations. Most abnormal central cusps are worn or fractured and can also cause periapical inflammation by the time they are diagnosed. Abnormal central cusps often cause pulp infection and necrosis via the pulp angle or exposed dentin tube, affecting the growth of the root, resulting in short root, thin root canal wall, and open apical foramina. For teeth with periapical infection caused by pulp necrosis due to abnormal central cusp fracture with an undeveloped root apex, nonsurgical treatments such as apexification, apical barrier technique, and regenerative endodontic procedure are commonly performed. These procedures have certain failure rates, and when they fail, it is more difficult to reperform the treatment, resulting in a poor prognosis, eventually leading to tooth extraction. The development and widespread use of dental microscopes, micro-instruments, ultrasonic instruments, cone-beam computerized tomography (CBCT), and new apical filling materials have contributed to the evolution of endodontic microsurgery in recent years. We performed endodontic microsurgery on 80 teeth in 78 patients with abnormal central apical fracture and periapical inflammation with unclosed apical foramina. Treatments with apexification, apical barrier technique, and regenerative endodontic procedure failed for these patients; thus, the curative effect of endodontic microsurgery was observed.

2.1 Participants

A total of 78 patients who visited the Department of Endodontics of Suzhou Stomatological Hospital from January 2021 to January 2022 were selected. The inclusion criteria were as follows: (1) abnormal central cusp fracture that caused pulp necrosis resulting in periapical inflammation, along with undeveloped tooth apex; (2) bone destruction or the presence of clinical symptoms despite the apical barrier technique or regenerative endodontic procedure being performed; (3) no systemic diseases. The exclusion criteria were as follows: (1) existence of periodontitis and resorption of the alveolar bone beyond one third of the apical or a crown-to-root ratio is less than 1:1; (2) complete absence of bone plate on the labial (buccal) side of the tooth or penetration of periodontal lesions with periapical lesions; (3) root length of < 10 mm with no value to preserve the tooth.

2.2 Data collection

Information regarding the patients’ age, sex, and other parameters was collected. Radiographs were obtained before surgery, immediately after surgery, and at 3 months, 6 months, and 1 year after surgery. The patients’ clinical symptoms, radiological data, and histopathological results were used to evaluate the transformation of the teeth and efficacy of endodontic microsurgery.

2.3 Surgical method

Preoperative radiographs and CBCT images were obtained to fully understand the morphology and length of the root, location and extent of periapical lesions, and their relationship with adjacent anatomical structures (including mental foramen and mandibular nerve canal). All procedures were performed by the same endodontic surgeon. The procedures were as follows: (1) After intra- and extra-oral disinfection, the surgical area was locally anesthetized with 1:100,000 epinephrine in 4% articaine. A gingival sulcus incision and a proximal vertical incision were created under the lens of a dental microscope (Zumax 2380, China) on the labial (buccal) side of the affected tooth. The mucoperiosteal flap was subsequently turned upward. (2) The apical of the affected tooth was located, and a contra-angle handpiece (ImpactAir45, Kerr) with a high-speed fissure bur was used to create a bone opening. The lesion tissue was entirely scraped and sent for histopathological examination. From the perpendicular axis to the central axis of the root, 1 mm of the root apex was removed using a long-handled fissure drill. The presence of root microfracture was examined after methylene blue staining under a high-magnification microscope. (3) An ultrasonic instrument was used to perform a 3-mm apical inversion to remove the root canal fillings with minimal damage to the dentin walls. (4) A 3-mm apical inversion filling was performed using iRoot BP (Innovative Bioceramix, Canada). (5) After confirming the absence of foreign bodies in the bone cavity, the bone walls were scratched to be filled with blood. The mucoperiosteal flap was restored and sewed using a 6 − 0 absorbable suture. (6) An X-ray was immediately captured, and the suture was removed 5–7 days after the surgery (Figs. 1 and 2)

2.4 Evaluation criteria

We evaluated the efficacy of the endodontic microsurgery 1 year after the surgery based on patients’ symptoms, clinical examination, and radiographs. (1) Complete healing was indicated by complete disappearance or approximate disappearance of apical dark shadow, lamina dura reappearance, no significant abnormality of periodontal membrane width, and no clinical symptoms and signs. (2) Incomplete healing was considered when the apical showed scar tissue formation with no clinical pain, swelling, or sinus tracts. (3) Uncertain healing was indicated by reduced apical dark shadow that was still larger than normal. (4) Unsatisfactory healing was considered when imaging showed that the size of apical dark shadow remained the same or expanded.

2.5 Statistical analysis

The SPSS 27.0 software package was used for data analysis. Nonparametric Wilcoxon signed rank test was used to analyze the effects of factors such as sex, age, distribution of teeth positions, presence of sinus tract, and extent of periapical lesion on the efficacy of endodontic microsurgery. The differences were considered statistically significant at a P value < 0.05.

The patients were aged 13–39 years, with an average age of 23 years. The study included 44 men and 34 women with 16 mandibular first premolars and 64 mandibular second premolars. Of them, 71 had undergone treatment with the apical barrier technique and 9 had undergone regenerative endodontic procedure. As a result, 77 of the 80 affected teeth were successfully treated, with a success rate of 96.3% (77/80). The endodontic microsurgery outcome showed no statistically significant differences (P > 0.05) with sex, age, distribution of teeth position, extent of periapical lesion, and presence of sinus tract (Table 1).

Table 1

Comparison of success rates between the groups
		Number of successful cases	Number of surgical failures	Total	Success rate
Age (years)	< 16	63	2	65	0.969
	> 16	14	1	15	0.933
Sex	Men	42	2	44	0.955
	Women	35	1	36	0.972
Sinus tract	Yes	54	2	56	0.964
	No	23	1	24	0.958
Teeth position	Mandibular first premolar	15	1	16	0.938
	Mandibular second premolar	62	2	64	0.969
Extent of periapical lesion	< 1 cm²	61	2	63	0.968
	> 1 cm²	16	1	17	0.941

Apexification is a classical method for treating teeth with incomplete apical development. According to a study^[2], the success rate of apexification is approximately 74–100%. Calcium hydroxide is the first choice for apexification; however, its application has many limitations, including long treatment course, unpredictability between apical closure and treatment time, and poor patient compliance with follow-up because of the long treatment course. Another concern is that long periods of calcium hydroxide exposure to the root canal walls will dissolve collagen and other bioactive matrix components of mineralized dentin. The resistance to root fracture will reduce drastically[^3] and may even prevent it from further development^[4]. Therefore, apexification affects the overall prognosis due to these factors.

Lin et al.^[5] compared the efficacies of apexification and regenerative endodontic procedures for periapical periodontitis in immature permanent teeth and found that the former had a slightly lower treatment success rate than the latter (89.8% and 97%, respectively). Furthermore, complications including discoloration and root canal calcification may occur. The root length and thickness increased significantly in apexification compared with those after regenerative endodontic procedures, reducing the possibility of postoperative root fracture in the affected tooth. Nevertheless, it is a challenge to control infection of the root canal during treatment. The choice of root canal disinfectant may directly or indirectly affect the survival of stem cells in the periapical tissue, making it impossible to predict its efficacy accurately^{[6, 7]}. The age of the patient should also be considered before treatment. Immature permanent teeth between the ages of 9 and 18 years can more suitably undergo regenerative endodontic procedures, and the prognosis worsens with an increase in age^[8].

The apical barrier technique involves the addition of a biocompatible artificial barrier directly in the apical region after controlling infection to achieve immediate root canal closure. It greatly reduces the treatment time and has become a preferred technique for treating teeth with open apices. Novel bioceramic materials such as iRoot BP have good biocompatibility, osteoconductivity, and clinical operability. This could enhance MC3T3-E1 preosteoblast activity in the acidic environment formed by anaerobic bacterial infection, facilitating periapical healing^{[3, 7, 9]}.

For permanent teeth with undeveloped apical foramina, whether apexification, apical barrier technique, or regenerative endodontic procedure is performed, a certain rate of failure exists due to the difficulty to control infection in the root canal, the lesion of periapical inflammation, and patients’ age and general condition. It may be difficult to treat teeth that failed nonsurgical treatment; thus, endodontic microsurgery can be performed to preserve the affected teeth. The advantage of endodontic microsurgery is that it promotes tissue healing by tightly sealing the root canal system under direct vision and creating an effective barrier preventing microorganisms from entering the periapical tissue. A recent retrospective analysis^[10] on endodontic microsurgery revealed a long-term survival rate of 95.2% in the affected teeth.

All 80 affected teeth included in this study were permanent premolars with abnormal central cusp fractures and open apical foramen, resulting in periapical inflammation. All had undergone treatment with the apical barrier technique or regenerative endodontic procedure. If the root canal infection is not effectively controlled during the follow-up of the previous treatment, apical surgery may be the sole option. Because the root is incompletely developed, the possibility of the existence of apical ramification of the lateral canal is low, and therefore, we did not perform the classical 3-mm apical resection required in endodontic microsurgery. Only 1-mm apical resection was performed to ensure an adequate crown-to-root ratio. Subsequently, we performed 3-mm apical inversion preparation and 3-mm apical inversion filling.

In both two failed cases, we found the existence of vertical root fracture (VRF) after tooth extraction. Endodontic treatment was the most common reason for VRF^[11]. The reasons^[12–14] were followed: (1) reduction of dentin thickness, (2) the existence of flat root, (3) use of EDTA and calcium hydroxide, and (4) dehydration of dentine. Thus, undeveloped root apex might be an important risk factor for VRF. Research^[15] showed that dentine thickness less than 1.3 mm increased the incidence rate of VRF. We removed a part of the dentin and root in the surgery. Therefore, protected dentine during endodontic microsurgery should be paid more attention. How to keep balance between removing bacteria and preserving dental tissue needs more research.

At the 1-year postoperative follow-up, failed surgery was noted in only 3 of the 80 affected teeth, with a success rate of approximately 96.3%. This demonstrates the feasibility of the endodontic microsurgery for preserving such teeth. However, the roots of the affected teeth were undeveloped. Long-term observation is required to understand whether the short length of the root or the thin dentine walls decreases root fracture resistance after endodontic microsurgery.

Availability of Data and Materials

The datasets generated and/ or analyzed during the current study are not publicly available due to privacy or ethical restrictions but are available from the corresponding author on reasonable request.

Consent for publication

Not Applicable.

Ethics approval and consent to participate

All experiments were performed in accordance with the ethical standards of the Research Ethics Committee, Suzhou Stomatological Hospital. The experiment was approved by the Ethics Committee of Suzhou Stomatological Hospital (20210101081) on 1/4/2021. Informed consent signed by their legal guardian and/ or themselves.

Acknowledgements

We thank TopEdit (www.topeditsci.com) for its linguistic assistance during the preparation of this manuscript.

Author Contributions

Y.T. wrote the main manuscript text; Y.C. and K.X. analyze data; and L.L. was responsible for supervising. All authors reviewed the manuscript.

Funding

The authors received no specific funding for this study.

Competing interests

The authors declare that they have no competing interests.

Author details

¹Department of Endodontics, Suzhou Stomatological Hospital, Suzhou 215005, China

²Department of Orthodontics, Suzhou Stomatological Hospital, Suzhou 215005, China

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No competing interests reported.

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You are reading this latest preprint version

Evaluate the Efficacy of Endodontic Microsurgery on Teeth Having Undeveloped Root Apex Failed in Non-surgical Treatment with Periapical Inflammation

Status:

Journal Publication

Version 1

Abstract

Figures

1. Background

2. Materials And Methods

2.1 Participants

2.2 Data collection

2.3 Surgical method

2.4 Evaluation criteria

2.5 Statistical analysis

3. Result

4. Discussion

5. Conclusion

Declarations

References

Additional Declarations

Status:

Journal Publication

Version 1