Evaluation of Staining Reduction of Teeth Endodontically Treated with CTZ Paste through the Use of Polytetrafluoroethylene Isolation Tape

ABSTRACT

Objective:  To evaluate the level of staining in teeth endodontically treated with CTZ paste with/without the use of polytetrafluoroethylene (PTFE) insulating tape and to identify the restorative material which is the most stable to pigmentation under different rhizolysis conditions.

Material and Methods:  50 human deciduous incisors were selected. The teeth received CTZ filling and were divided according to whether or not PTFE was used, as well as by the length of the remaining root (1/3 or 2/3 of the root) and by the restorative material (Modified Resin Glass Ionomer Cement or Opus Bulk Resin Fill Flow). Coloration was assessed once a week for six weeks through follow-up photographs. Pearson's chi-square or Fisher's Exact tests were used for intergroup and intragroup comparisons after six follow-up examinations (p < 0.05).

Results:  After six weeks of evaluation, it was possible to notice that 100% of the teeth without PTFE had their crowns stained by CTZ. Only 33.33% with PTFE showed staining (p<0.01). There was no statistical difference regarding the type of filling material (p=0.695) or the residual length of the roots (p=1.00).

Conclusion:  Using PTFE is an effective resource in preventing coronal staining in primary teeth endodontically treated with CTZ paste, regardless of the restorative material used to close the endodontic access or even the length of the root remnant.

Keywords:
Dental Pulp Necrosis; Pulpectomy; Glass Ionomer Cements; Composite Resins; Esthetics

Introduction

Several medical approaches have been proposed to promote the cleaning and disinfection of the root canals of primary teeth [¹], especially considering that the irregular topography of these canals prevents more straightforward instrumentation [²]. Understanding the changes related to molecular and cellular events during teeth development caused by therapeutic agents during tissue repair of endodontically treated primary teeth offers the opportunity to evaluate the biocompatibility of several therapeutic agents related to this treatment [³].

Based on this premise, the concept of Lesion Sterilization and Tissue Repair (LSTR) has been considered as an alternative for pulp therapy in devitalized primary teeth, a technique that does not require mechanical preparation and is based on the use of combinations of broad-spectrum antimicrobial agents’ performance [⁴,⁵]. Although LSTR has been practiced and promoted for over 25 years in Japan and Latin America, it was only recently that the AAPD recognized it as a helpful option in endodontics of primary teeth with irreversible pulpitis or necrosis under various diagnostic criteria [⁶].

Developed by Soller and Cappiello in 1959, CTZ paste comprises chloramphenicol, tetracycline, zinc oxide, and eugenol. It has stood out for its highly reported clinical and radiographic success rate, between 81.8-100% and 63-93%, respectively [¹,⁷]. Its success rate mainly lies in its easy technical execution and reduced clinical time, a condition especially advantageous in non-collaborative patients [⁸]. Even though CTZ paste is shown to be biocompatible with subcutaneous tissues in experimental models [⁹], its use has clear limitations, mainly due to the appearance of staining of the crown of deciduous teeth, turning them into a yellow-orange hue due to chloramphenicol and tetracycline impregnation. In this regard, such aesthetic aspect prevents wider application in anterior teeth.

Although not still widely investigated, some studies have recommended the application of sealing CTZ paste over a therapeutic cavity with the use of polytetrafluoroethylene (PTFE) tapes as an attempt to reduce the pigmentation of the crown in primary teeth, preserving their natural color [¹⁰,¹¹]. This technique is essential for maintaining self-esteem in children since the pigmentation of anterior deciduous teeth can negatively impact the quality of life [¹²,¹³].

Considering the need to avoid such side effects, PTFE tape presents itself as a potential resource for reducing tooth staining by sealing the coronal face of the endodontic access [¹⁴]. This tape comprises an inert, ultra-thin, non-porous, and malleable viscoelastic polymer, easily adapted to different teeth contours and cavities [¹⁰]. The search for innovative methods and materials in pediatric dentistry has been fundamental for expanding access to safe and effective treatments for children. However, some scientific gaps still prevail regarding the effectiveness of sealing the CTZ paste using PTFE tape, the best indication of restorative material for crown color stability, and the presence of different rhizolysis conditions.

Therefore, this study aims to evaluate the reduction of teeth staining endodontically treated with CTZ paste through polytetrafluoroethylene isolation tape. In addition, this work helps identify the restorative material most stable to pigmentation under different rhizolysis conditions.

Material and Methods

Study Design and Ethical Clearance

This in vitro study was reviewed and approved by the research ethics committee of the Federal University of Alagoas (Opinion No. 6.668.063).

Teeth Selection and Preparation

Human deciduous incisors with healthy crowns were selected through the tooth bank of the Faculty of Dentistry. After the initial inspection, teeth with fractures, cracks, and restoration were excluded. Fifty teeth were included in this study. The teeth were cleaned for debris removal and stored in 0.9% saline solution. All teeth were endodontically accessed using 1011 spherical diamond burs (KG Sorensen Indústria e Comércio LTDA, Serra, ES, Brazil) and endo Z drill FG (Microdont Comercio Imp. e Exp. de Produtos Ltda., São Paulo, SP, Brazil) at high speed. Using a 329 carbide drill (KG Sorensen Indústria e Comércio LTDA, Serra, ES, Brazil ), the canal entrances were enlarged to an opening of 1mm in diameter and 2mm in depth, thus creating a therapeutic cavity to receive the CTZ paste. After this step, the canal systems were irrigated with saline solution. Subsequently, The CTZ paste was compounded in a compounding pharmacy (A formula, Maceió, AL, Brazil) in proportions 1:1:2 (chloramphenicol, tetracycline, and zinc oxide) in portioned capsule format. To manipulate the paste, three drops of eugenol (approximately 0.15mL) were added to the capsule content (on a glass plate and spatulated with a spatula 26), forming a sandy paste. Subsequently, the CTZ paste was inserted with a spatula and then condensed with a condenser at the entrance of the root canals. All root apices were closed by inserting composite resin to prevent CTZ paste from escaping through the root foramen under the rhizolysis process.

Thereafter, the teeth were randomized into groups according to whether or not they received the isolation tape (TDV Dental, Pomerode, SC, Brazil). Furthermore, the teeth were also randomized according to the remaining root and type of restorative filling material. The restorative materials were Resin-Modified Glass Ionomer Cement (RMGIC; GC Gold label 2LC Light Cured Universal Restorative) or Opus Bulk Fill Flow Resin (FGM Dental Group, Joinville, SC, Brazil) as a filling material for coronary access. Both fill materials were color A2. The palatal face of both groups was restored with a thin layer of composite resin (Vittra APS Unique, FGM Dental Group, Joinville, SC, Brazil), which has chameleon-like properties. Therefore, this study is composed of 8 groups, as defined below:

• G1 (7 Teeth) - 1/3 of root remaining + isolation tape + restoration with Resin-Modified Glass Ionomer Cement as filling material.

• G2 (7 Teeth) - 1/3 of root remaining + isolation tape + restoration with Opus Bulk Fill Flow resin as filling material.

• G3 (6 Teeth) - 2/3 of root remaining + isolation tape + restoration with Resin-Modified Glass Ionomer Cement as filling material.

• G4 (7 Teeth) - 2/3 of root remaining + isolation tape + restoration with Opus Bulk Fill Flow resin as filling material.

• G5 (5 Teeth) - 1/3 of root remaining + without isolation tape + restoration with Resin-Modified Glass Ionomer Cement as filling material.

• G6 (6 Teeth) - 1/3 of root remaining + without isolation tape + restoration with Opus Bulk Fill Flow resin as filling material.

• G7 (6 Teeth) - 2/3 of root remaining + without isolation tape + restoration with Resin-Modified Glass Ionomer Cement as filling material.

• G8 (6 Teeth) - 2/3 of root remaining + without isolation tape + restoration with Opus Bulk Fill Flow resin as filling material.

Afterward, the teeth were inserted into test tubes with 20 mL of saline solution. Coloration was assessed once a week for six weeks. In this regard, a professional camera EOS T7 (Canon Inc., Tokyo, Japan) with a 100 mm macro EF lens and flash equipment was used 30cm from the tooth. The camera was positioned on a tabletop tripod for photographs. Follow-up photographs were constantly compared with the picture taken in the first week to identify any possible color changes in the tooth's crown (Figure 1). Whenever a color change was observed, the outcome was considered as staining. The examinations were performed by a calibrated examiner for visual examination to change the crown's color. Kappa coefficients for the intra-examiner agreement were K = 0.90.

Figure 1
Change in color after six weeks of evaluation. Group without tape, filled with RMGIV and 2/3 of the remaining root.

Data Analysis

After data collection and the categorization of variables, a database was created for statistical analysis using IBM SPSS Statistics for Windows version 17 (IBM Corp., Armonk, NY, USA). The chi-squared or Fisher's exact test was used to test the association between two categorical variables. The margin of error was 5%.

Results

After six weeks of evaluation, it was possible to notice that 100% of the teeth without PTFE insulation had their crowns stained by CTZ (Figure 2). Only 33.33% showed this staining among those who used this insulation. Moreover, a statistically significant difference was verified between these groups (p<0.001). The relative risk of staining is 3 times higher in the group that did not use PTFE tape.

Figure 2
Temporal analysis of the effectiveness of the use of TPFE against tooth staining.

Analyzing the effectiveness of the use of PTFE in terms of reducing staining caused by CTZ showed that there is no statistically significant difference for the use of RMGIC or Bulk Fill Flow resin (p=0.695), nor in terms of the amount of root remnant (p=1.00) in the group where the tape was applied. On the other hand, all teeth in the group without the tape were stained at the end of the six weeks. Therefore, there is no difference in the filling material type or even the amount of root remaining (Table 1).

Table 1
Coronal staining in deciduous teeth after using CTZ paste and its relationship with PTFE tape, restorative material, and root remnants.

Variables	Tooth Staining			p-value	RR (IC 95%)
	No	Yes	Total
Without PTFE	0	23	23	0.001†*	3 (1.75 to 5.11)
With PTFE	18	9	27		1
Intragroup Analysis - With PTFE
RMGIC	8	5	13	0.695¥	1
Bulk Fill	10	4	14		1.34 (0.45 to 3.95)
1/3 root remaining	9	5	14	1.00†	1.16 (0.39 to 3.40)
2/3 root remaining	9	4	13		1
Intragroup Analysis - Without PTFE
RMGIC	0	11	11	**
Bulk Fill	0	12	12
1/3 root remaining	0	11	11
2/3 root remaining	0	12	12	**

• ^†
  Chi-square test;
• ^¥
  Fisher's Exact test;
• ^*
  Statistically significant;
• ^**
  It is not possible to calculate the p-value due to null frequencies.

Discussion

PTFE tape is a material widely used in several fields, including dentistry. However, the relationship between the use of PTFE tape and the reduction of stains on primary teeth after the use of paste based on chloramphenicol, tetracycline, zinc oxide, and eugenol (CTZ) has not been widely explored in the scientific literature [¹⁰,¹⁴]. Endodontic treatment in primary teeth is essential to preserve oral health and ensure the adequate development of permanent teeth. Therefore, CTZ paste is often used in these procedures due to its antibacterial properties, besides not requiring mechanical instrumentation in the root canals [¹⁵-¹⁷]. However, one of the side effects of this paste is the potential for tooth stains, an aesthetic inconvenience that occurs in primary anterior teeth, constituting a limitation and contraindication of the technique.

Studies have shown that the composition of CTZ paste, especially the presence of tetracycline, can cause teeth stains, especially in primary teeth. In this context, the search for strategies to reduce or prevent this staining becomes relevant to guarantee the success of endodontic treatment and the aesthetics of children's smiles. This adverse effect becomes evident three weeks after its application, as shown in the present study's findings (Figure 2). In anterior teeth, intense yellowing of the dental crown, such as that caused by CTZ paste, can generate aesthetic discomfort for children and their relatives [¹²,¹³]. Although this problem could traditionally be resolved with composite resin veneers or zirconia crowns, this decision would significantly increase costs [¹⁸,¹⁹] and sessions, leading to iatrogenic events inherent to dental conduct and techniques [²⁰].

From this scenario emerges a simple and low-cost technique related to the isolation of the CTZ paste, limiting it to the root canal. This management is associated with using PTFE tape at the entrance to the root canal, more precisely over the entire therapeutic cavity created for inserting this paste, isolating the root canal from the coronary access region to be filled with restorative material [¹⁰,¹¹]. This technique takes advantage of the malleable properties of PTFE tape, which easily adapts to dental contours and is non-porous, preventing contact with different materials used for dental rehabilitation [¹⁴]. Although such application is not widespread and its success is limited to its applications in primary dentition [¹⁰,¹⁴], this research's results indicate that using such insulating tapes prevents tooth staining caused by the use of CTZ paste. Results show that using PTFE tapes prevented staining in 66.67% of teeth treated with CTZ after six weeks. On the other hand, 100% of the teeth were stained after this period in the group that did not use the tape.

Absorption is the material's ability to incorporate or assimilate another substance or material, entering its constitution. Adsorption is the material's ability to retain another substance or material only on its subsurface [²¹,²²]. Both properties provide the basis for the change in color of the filling materials used in this study (RMGIC and bulk fill flow). However, although they are color-stable materials over time, their use in conjunction with CTZ paste caused pigmentation to occur in these materials, regardless of whether or not PTFE tape was used. Therefore, the choice of material was not a condition that interfered with preventing stains caused by this contact, both in the group with and in the group without using PTFE tape.

A systematic review [²³] recommended using LSTR only in teeth with resorbed roots, as with antimicrobial pastes, especially CTZ [¹⁷]. As this paste is placed in the therapeutic cavity, located at the entrance to the root canal, it acts across the entire length of the root through diffusion and in both directions, coronal and radicular. In this study, it was possible to verify that, for coronal staining, the length of the root remnant does not influence the prevention of this side effect. Although staining occurred in two groups, using PTFE tape isolates the main communication between CTZ and the pulp chamber, protecting it from staining, similar to the results of the indices presented herein. However, staining may also have occurred due to diffusion by the dentinal tubules, a condition that would not be protected by using the tape alone.

However, it is worth highlighting that in vitro laboratory studies have some critical limitations and disadvantages to be considered, such as a controlled environment, which may not reflect interactions with a biological environment; limitations in clinical applicability, as some techniques and results are limited to the effect achieved in the laboratory, leading to results that are not possible to extrapolate for use in humans; as well as possible experimental artifacts and ethical and regulatory limitations. Therefore, although in vitro studies are valuable tools for scientific research, it is essential to be aware of their limitations and complement these studies with other approaches, such as randomized clinical trials.

Conclusion

The use of polytetrafluoroethylene tape is an effective resource for preventing coronal staining in primary teeth that have been endodontically treated with CTZ paste, regardless of the restorative material used to close the endodontic access or even the length of the root remnant.

• Financial Support
  None.

Data Availability

The data used to support the findings of this study can be made available upon request to the corresponding author.

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Edited by

• Academic Editor:
  Alessandro Leite Cavalcanti

Publication Dates

• Publication in this collection
  17 Mar 2025
• Date of issue
  2025

History

• Received
  28 May 2024
• Reviewed
  30 July 2024
• Accepted
  16 Sept 2024