Comparative evaluation of bioglass nanofiber, dexamethasone-coated bioglass nanofiber, and platelet-rich fibrin, as scaffolds in regenerative endodontic treatment of immature necrotic teeth: A randomized controlled trial

Abstract

Aim:

The aim of this study was to evaluate and compare the regenerative endodontic potential of dexamethasone-coated bioglass nanofiber (Dex-BGnf), bioglass nanofiber (BGnf), and platelet-rich fibrin (PRF) for inducing regeneration in necrotic immature permanent teeth.

Materials and Methods:

A total of 36 (n = 12) immature necrotic teeth with or without evidence of periapical lesion were included in the study. Patients were randomly allocated into three groups, based on the scaffolds used: Group I (PRF), II (BGnf), and III (Dex-BGnf). The clinical (electric pulp test) and radiographic evaluations (percentage increase in apical diameter, root length, root dentin thickness, and periapical healing) were compared at 6 and 12 months after the procedure with baseline records.

Statistical Analysis:

One-way ANOVA, post hoc Tukey analysis, and Kruskal–Wallis test were used for evaluating the data. A 6- and 12-month improvement analysis was done using paired t-test and Friedman test.

Results:

Clinically, all the 36 teeth were asymptomatic, but none gave a positive response to Electric Pulp Test (EPT) in time interval of 12 months. Dex-BGnf showed a statistically significant improvement in terms of increase in root length (P = 0.020) and root dentinal thickness (P = 0.001) when compared to PRF after 12 months.

Conclusion:

The study has shown that Dex-BGnf yielded significantly better results than PRF for inducing apexogenesis in necrotic immature teeth.

INTRODUCTION

Regenerative endodontics is a physiological process that encourages continued root development with an increase in root length, dentin thickness, and apical closure.[1,2] According to Hargreaves et al.,[3] there are three essential components required for a successful procedure: stem cells, growth factors, and scaffold. Ideal scaffolds are biocompatible structures that allow cellular attachment, migration, proliferation, and differentiation and provide mechanical support for the extracellular matrix generation.[4]

Platelet-rich fibrin (PRF) was developed in France by Choukroun et al., in 2001,[5] and is considered the golden standard of scaffolds.[6,7] Positive outcomes may be attributed to the presence of platelet-specific and nonspecific proteins in the granules.[8,9] Activation and degranulation of these granules releases cytokines (interleukin-1β [IL-1 β], IL-6, tumor necrosis factor-α) and tumor growth factors (tumor growth factor β1), platelet-derived growth factor, vascular endothelial growth factor, and epidermal growth factor that stimulates cell migration and proliferation.[9]

Bioactive glass are synthetic reactive materials that possess the ability to support osteogenesis and pro-angiogenesis.[10] With advancement, many biomatrices such as porous foams, microchannel scaffold, and nanofibers have been probed. Nanofiber matrices emerged superior due to their mimicking nature of native extracellular matrix.[11] Addition of bioactive molecules such as dexamethasone (DEX) further improved their osteogenic lineage differentiation by upregulating levels of alkaline phosphatase and bone morphogenetic protein 2 (BMP-2).[12] However, the direct use of DEX has been limited due to its toxic side effects, but delivery via incorporation into biomaterials is favored.[13,14]

The study aims to compare and evaluate the regenerative endodontic potential of PRF, BGnf, and dexamethasone-coated bioglass nanofiber (Dex-BGnf) scaffolds in immature necrotic permanent teeth. Null hypothesis stating no statistical difference in regenerative potential of PRF, BGnf, and Dex-BGnf was formulated.

MATERIALS AND METHODS

This clinical study was conducted in the Department of Conservative Dentistry and Endodontics after receiving approval from the Ethical Committee of the Institute (No. Dean 2019/EC/1715). Trial was registered in Clinical Trials Registry India with CTRI no. CTRI/2021/07/034841. The total sample size of 36 (12/group) with 95% power of the study was calculated using G*Power software (Heinrich Heine University, Dusseldorf, Germany). Thirty-six immature necrotic permanent teeth were selected and divided randomly using a computer-based program (www.random.org) into three groups; PRF, BGnf, and Dex-BGnf.

Eligibility criterion

10–35-year-old patients with necrotic immature permanent anterior teeth; with or without periapical radiolucency; and presenting with pain, tenderness, swelling, and sinus were randomly selected in the study without any gender predilection. Patients with any medical conditions, tooth that requires post and core, severely curved canals, and patients allergic to any materials used in this study were excluded.

MATERIALS AND METHODS

Nano-biomatrices and dexamethasone loading

Bioglass nanofiber (BGnf) and Dex-BGnf group scaffolds were prepared in the School of Materials Science, IIT, BHU, using sol-gel approach. Nanofibers were generated using electrospinning technique and allowed to adhere on aluminum sheets [Figure 1a and b]. 5 mg/mL DEX was allowed to adsorb on bioglass surface. DEX release pattern was evaluated by absorbance at 242-nm ultraviolet-visible spectrometry (Libra S22, Biochrom) for 150 h [Figure 1c]. The prepared scaffolds were examined for the nanostructure morphologies by scanning electron microscopy [Figure 1d and e].

Figure 1.

(a) Bioglass nanofiber scaffold, (b) Dexamethasone-coated bioglass nanofiber scaffold, (c) Percent drug release in 150 h, (d) SEM of bioglass nanofiber (×4000, ×1100), (e) SEM of dexamethasone-coated bioglass nanofiber (×4000, ×1100), (f) Access cavity preparation, (g) Bleeding induced, (h) Scaffold placed in the canal, (i) 2–3-mm Biodentine barrier, (j) GIC restoration, (k) Case presentation (A. Preoperative IOPA, B. Working length IOPA, C. 3-month postoperative IOPA, D. 6-month IOPA, E. 12-month IOPA). SEM: Scanning electron microscope, GIC: Glass Ionomer Cement, IOPA: Intra Oral Peri-Apical

Clinical procedure

The detailed treatment protocol was explained to the patients (or parents if the patient was <14 years of age), and informed consent was obtained before commencing the treatment.

Preoperative Intra Oral Peri-Apical (IOPA) records were administered and apical diameter, root length, and root dentin thickness were recorded using ImageJ software. Periapical radiolucency was recorded using Peri Apical (PAI) Index (Orstavik et al.):[15]

1. Normal periapical structures

2. Small changes in bone structure

3. Change in bone structure with mineral loss

4. Well-defined radiolucent area

5. Large radiolucent area with exacerbating features and bone expansion.

Under rubber dam isolation, access opening was initiated with #2 round diamond bur (Endo Access Bur, DENTSPLY, Maillefer). Once drop within the pulp chamber was felt, axial wall modifications were done with safe tip Endo-Z bur (DENTSPLY, Maillefer). The canals were then copiously irrigated using 1.5% sodium hypochlorite solution (20 ml) (Septodont, Saint-des-Fosses, France) and sterile normal saline (10 ml) using a 29-G, side-vented needle (Navitip, Ultradent).

After canals were dried using sterile paper points, double antibiotic paste (1:1 ciprofloxacin + metronidazole, self-prepared) was applied to the canals with the help of Lentulo Spiral (DENTSPLY, Maillefer) for 4 weeks. Access cavity [Figure 1f] was then restored using temporary filling material, Cavitemp (AMMDENT, Mohali, India).

After 4 weeks, when patients were reported asymptomatic, local anesthesia without adrenaline (LOX 2%, Neon) was administered. The double antibiotic paste was washed out of the canal using sterile k-file (DENTSPLY, Maillefer) and copious irrigation using 1.5% sodium hypochlorite solution followed by irrigation with sterile saline (10 ml) and 17% ethylenediaminetetraacetic acid (EDTA) (Cerkamed) (10 ml) was done. Canals were finally dried using paper points (DENTSPLY Paper Points). A sterile #20 k-file (DENTSPLY, Maillefer) was purposefully passed 2 mm beyond the confines of working length to evoke bleeding into the canal [Figure 1g]. A tight cotton pellet moistened with normal saline was inserted into the root canal for 10 min, to induce clot formation.

In the PRF group, scaffold was prepared from patients' blood in centrifugal machine with rotations at 2700 rpm for 14 min. The PRF was carefully withdrawn and inserted into the canal using PRF instruments and hand plugger.

In the BGnf and Dex-BGnf groups, scaffolds were cut longitudinally from aluminum foil and rolled using a pair of tweezers and introduced into the canal using hand plugger [Figure 1h]. Then, access cavity was filled with 2–3 mm Biodentine (Septodont, France) [Figure 1i] and the remaining cavity was restored using glass-ionomer cement (GC, Tokyo, Japan) [Figure 1j].

All the radiographic geometries were standardized with the help of XCP positioner (Dentsply). For all the cases, postoperative intraoral periapical radiographs were taken at 6- and 12-month intervals and evaluated by two independent and blinded observers [Figure 1k]. Patients were blinded too to avoid any risk of bias.

An increase in root length, apical diameter, and dentin thickness parameters was measured quantitatively using ImageJ software.

Calculation of percentage increase in root length [Figure 2a]

Figure 2.

(a) Calculation of percentage change in root length, (b) Calculation of percentage change in apical diameter, (c) Calculation of percentage increase in root dentin thickness

Figure 3.

CONSORT flow diagram of eligible patients up-to 12 months follow-up. Group1: PRF; Group 2: Bioglass nanofiber; Group 3: Dexamethasone coated Bioglass nanofiber

The root length was measured as a straight line from the cementoenamel junction (CEJ) to the radiographic apex of the tooth. The average root length was calculated by mean of root length at mesial and distal sides. The mesiodistal width at CEJ of the tooth was considered a reference point for calculating magnification factor among the radiographs.

Calculation of percentage increase in apical diameter[Figure 2b]

The apical diameter was measured as a straight line across the radiographic apical foramen. Change in magnification was found insignificant.

Calculation of percentage increase in dentin thickness [Figure 2c]

The root area was measured using polygon section area measurement tool in ImageJ software. For root dentin thickness measurement, area of the root canal space was subtracted from the area of the root. Postoperative measurements were calibrated for magnification as done in root length measurements.

Statistical analysis

Statistical analysis was conducted using SPSS software (26.0, IBM, Corp, Armonk, New York, USA).

Quantitative percentage increase in apical closure, dentin thickness, and root lengthening was analyzed using one-way ANOVA test. Intergroup comparison was done using post hoc Tukey analysis. Periapical healing being qualitative parameter was evaluated using Kruskal–Wallis Test. Six- and 12-month follow-ups were compared using paired t-test in quantitative data and Friedman test in qualitative data.

OBSERVATIONS AND RESULT

All 36 subjects were completely asymptomatic throughout the study period with no tenderness to palpation and percussion. The swelling and sinus tract resolved completely and did not reappear in 6- and 12-months recall.

All subjects gave negative response to EPT, but showed improvement in terms of apical closure, root lengthening, dentinal wall thickening [Table 1a and b], and periapical healing [Table 2] at an interval of 6 and 12 months.

Table 1a.

Comparative Quantitative analysis of percentage increase in apical diameter, root length and root dentin thickness at end of 6 and 12 months for groups I, II, III.

Group	Percentage change in Apical diameter		Percentage Increase in Root length		Percentage Increase in Root Dentin thickness
	Mean±SD (6 months)	Mean±SD (12 months)	Mean±SD (6 months)	Mean±SD (12 months)	Mean±SD (6 months)	Mean±SD (12 months)
Group I: PRF (12)	5.57±6.44	19.1±10.36	4.39±5.65	4.93±6.04	2.33±2.56	7.34±4.80
Group II: BGnf (12)	5.96±4.05	22.18±16.01	4.36±3.0	7.75±2.23	4.88±4.01	15.53±6.58
Group III: Dex- BGnf (12)	12.77±12.05	35.18±26.60	6.21±7.91	13.08±3.78	7.99±5.45	21.25±11.75
ANOVA Test	F=2.90	F=2.448	F=0.0385	F=4.386	F=5.501	F=8.607
	P=0.669(NS)	P=0.102(NS)	P=0.020(S)	P=0.020(S)	P=0.009(S)	P=0.001(S)
			Post hoc Analysis: III≥II, II≥I, III>I	Post hoc Analysis: III≥II, II≥I, III>I	Post hoc Analysis: III≥II, II≥I, III>I	Post hoc Analysis: III≥II, II≥I, III>I

Table 1b.

Comparative Qualitative analysis for Group I, II, III at 6 and 12 months interval

Parameter	Percentage change in Apical diameter		Percentage change in Root length		Percentage change in Root dentin thickness
Time Duration	6 months	12 months	6 months	12 months	6 months	12 months
Group I: PRF
Mean±S.D.	5.57±6.44	19.1±10.36	4.39±5.65	4.93±2.93	2.33±2.56	7.33±4.80
Paired t-test	0.000 (S)		0.769 (NS)		0.0009 (S)
Group II: BGnf
Mean±S.D.	5.96±4.05	22.18±16.01	4.36±3.30	12.81±7.75	4.88±2.56	15.5±6.58
Paired t-test	0.001 (S)		0.000 (S)		0.000 (S)
Group III: Dex-BGnf
Mean±S.D.	12.77±12.05	35.18±26.60	6.21±7.41	16.04±13.08	7.99±5.45	21.25±11.75
Paired t-test	0.001 (S)		0.000 (S)		0.000 (S)

Table 2.

Comparative Qualitative analysis of periapical healing at end of 12 months for groups I, II, III

Groups	Pre-operative Score					Score at 6 months					Score at 12 months					Friedman Test
	1	2	3	4	5	1	2	3	4	5	1	2	3	4	5
Group I (12)	0	3	3	5	1	4	7	0	1	0	9	3	0	0	0	Chi-sq=20.6
		(25)	(25)	(41.67)	(8.3)	(33.3)	(58.3)		(8.3)		(75)	(25)				P=0.000(S)
Group II (12)	0	1	2	7	2	3	8	1	0	0	10	2	0	0	0	Chi-sq=21.81
		(8.3)	(16.67)	(58.33)	(16.67)	(25)	(66.7)	(8.3)			(83.33)	(16.67)				P=0.000(S)
Group III (12)	0	1	4	5	2	6	3	3	0	0	11	1	0	0	0	Chi-sq=22.29
		(8.3)	(33.33)	(41.67)	(16.67)	(50)	(25)	(25)			(91.67)	(8.3)				P=0.000(S)

Percentage increase Root lengthening

After 6 months, the mean percentage increase in root length in PRF, BGnf, and Dex-BGnf was 4.39±5.65%, 4.36±3.0% and 6.21±7.91% respectively. [Table 1a] After 12 months recall Dex-BGnf showed the highest improvement to 13.08±3.78%, followed by BGnf and PRF with mean of 7.75±2.23% and 4.93±6.04% respectively. [Table 1a] Statistically significant difference were observed between Dex-BGnf and PRF after 12 months postoperatively (P<0.05).

Percentage Increase in Apical diameter

After 6 months, the mean percentage increase in apical diameter in PRF, BGnf, and Dex-BGnf was 5.57±6.44%, 5.96±4.05% and 12.77±12.05% respectively [Table 1], which statistically improved [Table 1b] to 19.1±10.36%, 22.18±16.01%, 35.18±26.60% respectively [Table 1a] after 12 months recall. Though Dex-BGnf showed highest percentage change, but the results were statistically non-significant (P > 0.05).

Percentage increase in Root Dentinal wall thickening

After 6 months, the mean percentage increase in root in Group PRF, BGnf, and Dex-BGnf was 2.33±2.56%, 4.88±4.01% and 7.99±5.45% respectively. [Table 1a] After 12 months, significant (P = 0.000) [Table 1b] improvement was observed where, Dex-BGnf group was showing the best results with mean increase of 21.2±11.75%, followed by Bgnf (15.53±6.58%.) and PRF (7.34±4.80%). [Table 1a] The difference was statistically significant between Dex-BGnf and PRF (P < 0.05)

Periapical healing

All the groups showed significant improvement in periapical healing from 6 months to 12 months recall (P < 0.05, Table IV). In PRF group, 41% subjects had a preoperative score of 4, which latter improved to 75% subjects having score 1. Similarly, 83% and 92% subjects in BGnf and Dex-BGnf Group respectively, improved to score 1. [Table 2] But when three groups were compared against each other, no significant differences were observed in 6 (P > 0.05) and 12 months (P > 0.05) follow-up.

Considering all the four parameters, null hypothesis was rejected (P < 0.05). Dex-BGnf Group was showing better results with respect to PRF in terms of increase in root length and dentinal wall thickening. While no significant difference was observed in terms of apical closure and post operative healing.

DISCUSSION

A successful regenerative endodontic therapy depends on proper disinfection, biocompatible scaffold, transport of signaling molecules, and a coronal seal to prevent reinfection.[3,4]

1.5% sodium hypochlorite (NaOCl) irrigation provides adequate disinfection with maximum survival of Stem Cell from Apical Papilla (SCAP) and greater dentin sialophosphoprotein (DSPP) expression, which are crucial for regeneration.[16] 17% EDTA irrigant was used just before inducing bleeding, which facilitates liberation of growth factors from root dentin, increasing survival, and expression of DSPP and partially reverses deleterious effects of NaOCl.[17]

In tissue regeneration, selection of the suitable scaffold is critical. According Chandrahasa et al.,[18] different chemical compositions of scaffolds adversely influence the rate of dental pulp cell proliferation.

Till date, nine different in vitro and in vivo studies have been conducted comparing regenerative potential of PRF with blood clot and different natural and artificial scaffolds. PRF has shown superior results in almost all the studies. Except for one where Platelet Rich Plasma (PRP) shows better results due to the presence of 3–5 times higher platelet concentration than PRF.[10] This may also be seen because of shorter follow-up duration and dropouts in that study. One meta-analysis study conducted by Murray[19] reviewed 222 cases treated using PRF, PRP, and blood clot, where PRF proved to possess superior regenerative potential with a success rate of 85.2%.

Mandakhbayar et al.[20] conducted an in vitro study comparing conventional and nano-bioglass. The latter yielded better results in terms of healing, dentin deposition, and root lengthening, as seen in our study too. Total 7 in vitro and 3 animal studies have been conducted where, in every study, nano-bioglass has shown excellent potential for odontogenesis of Dental Pulp Stem Cells (DPSCs).[21,22] The nanotopological cues are possible explanation behind such findings. Stem cells recognize nanofibrous topology to adhere and spread well, which later accentuates the osteoblastic activity of human dental pulp cells (HDPCs).[22]

Odontogenic potential of DEX has been explored in 7 in vitro and 2 animal studies till date, but no human trial has yet been conducted. In an in vitro study by Kim et al.,[23] delivery of DEX drug with nano-bioglass vehicle potentiated the odontogenic differentiation of HDPCs by upregulating expression of BMP-2, Akt (protein kinase B), and mammalian target of rapamycin pathways. In the present study, release of DEX drug was recorded for up to 150 h [Figure 1c]. The release was observed in 2 stages, initial rapid release (10 h), which may be due to the presence of trapped DEX molecules in the biopolymer matrix. Later, the release was consistent to the period tested. El-Fiqi et al.[24] supported this pattern, where a continued release of DEX over a period of time is believed a great merit in inducing odontogenesis.

In our study, none of our test subjects yielded positive EPT; this may be due to short 12-month postoperative follow-up. Out of all 36 cases, 8 cases were showing ongoing apical closure (percentage apical closure >40%), out of which 5 cases were in Group Dex-BGnf. Maximum percentage apical closure was seen in 2 cases at 12-month interval, 85.7% and 82.3%, respectively, both in Group Dex-BGnf. Maximum percentage increase in dentin thickness and root length was also appreciated with Dex-BGnf, 48.85% and 40.24%, respectively. Thus, one may confer the promising regenerative potential of the scaffold.

Limitations of the study

Short-term follow-up period and two-dimensional radiographic analysis are the drawbacks of the study, because pulp sensibility tests and radiographic changes generally take time of 14–18 months to show positive responses.

CONCLUSION

This study compared regenerative potential of two nano-scaffolds: BGnf and Dex-BGnf with PRF in immature necrotic tooth. Considering all regenerative objectives and methods used in this study, Dex-BGnf scaffold is found to be a significantly (P < 0.05) better scaffold with respect to PRF. However, further in vivo long-term studies are warranted for better understanding of the potential of dexamethasone-coated nano-drug delivery system in regenerative endodontics.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.