Long-Term Evaluation of Direct Composite Resin Restoration for Traumatic Anterior Crown Fractures in Children and Adolescents

Selin Lee; Seong Joon Lee

doi:10.5933/JKAPD.2024.51.4.407

J Korean Acad Pediatr Dent > Volume 51(4); 2024 > Article

Lee and Lee: Long-Term Evaluation of Direct Composite Resin Restoration for Traumatic Anterior Crown Fractures in Children and Adolescents

Original Article

J Korean Acad Pediatr Dent 2024;51(4): 407-416.

Published online: November 25, 2024

DOI: https://doi.org/10.5933/JKAPD.2024.51.4.407

Long-Term Evaluation of Direct Composite Resin Restoration for Traumatic Anterior Crown Fractures in Children and Adolescents

Selin Lee¹

, Seong Joon Lee^1,²

¹Department of Pediatric Dentistry, Wonju Severance Christian Hospital, Yonsei University, Wonju, Republic of Korea

²Department of Dentistry, Wonju College of Medicine, Yonsei University, Wonju, Republic of Korea

Corresponding author: Seong Joon Lee Department of Pediatric Dentistry, Wonju Severance Christian Hospital, Wonju College of Medicine, Yonsei University, 20, Ilsan-ro, Wonju, 26426, Republic of Korea
Tel: +82-33-741-1313 / Fax: +82-33-741-1442 / E-mail adress: color1513@naver.com

Received August 19, 2024 Revised September 21, 2024 Accepted September 24, 2024

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Direct composite resin restorations are often the first choice in children and adolescents with anterior crown fractures. This study aimed to assess the long-term outcomes of direct composite resin restoration in children and adolescents with traumatic dental injuries. Patients with anterior crown fractures treated with direct composite resin restoration at the Department of Dentistry of Wonju Severance Hospital between March 2011 and February 2022 were included. A total of 86 teeth from 59 patients were evaluated. The survival rate according to the sex, age, history of pulp treatment, and ratio of the resin restoration to the clinical crown were statistically calculated using chi-square test, Fisher’s exact, and Kaplan-Meier methods. Factors associated with failure were evaluated using Cox regression analysis. Survival rates during the follow-up period were significantly different according to the patient’s age at the time of trauma (p = 0.036). The survival rate was not significantly different between the sexes (p = 0.632). The survival rate was not influenced by pulp treatment before resin restoration (p = 0.617). Based on the Kaplan-Meier method, the mean retention time of teeth with and without pulp treatment was 99.35 ± 9.98 and 79.68 ± 9.07 months, respectively. Additionally, there was no significant difference between both survival curves (p = 0.215). Furthermore, the survival rate was not significantly different according to the ratio of the resin restoration to the clinical crown (p = 0.334). Similar to the results from Fisher’s exact test, there was no significant difference in survival rates between Group I (ratio of the resin restoration to the clinical crown < 0.5) and Group II (ratio of the resin restoration to the clinical crown ≥ 0.5) (p = 0.228). This study demonstrates the clinical efficacy of direct composite resin restorations for anterior crown fractures in children and adolescents, with favorable survival rates observed over 10 years of follow-up suggesting it as a conservative and effective primary treatment option across various clinical conditions.

Keywords: Conservative treatment, Tooth fractures, Composite resins, Dental restoration failure

Introduction

Trauma to the permanent teeth is one of the problems that frequently occurs in children and adolescents. Crown fracture is a common traumatic dental injury, especially in the anterior teeth[1,2]. Previous studies suggested that the anterior teeth trauma is the most frequent among dental trauma[3,4]. The common causes of pediatric dental trauma are falls, collisions, traffic accidents, and cycling[5]. These incidents often occur during play, sports activities, or as a result of accidents. The anterior teeth, particularly the maxillary central incisors, are most vulnerable due to their prominent position in the dental arch. The anterior teeth play an important role in aesthetics. The impact of dental trauma, especially to the anterior teeth, extends far beyond physical damage. Therefore, damage due to trauma can have undesirable physical, emotional, and mental effects in daily social and school life[6]. Visible dental injuries can lead to decreased self-esteem, social anxiety, and difficulties in social interactions. Studies have shown that children with untreated dental injuries may experience teasing or bullying, which can negatively impact their academic performance and overall well-being[7]. Therefore, anterior teeth with crown fractures require appropriate treatment.

In childhood and adolescence, traumatized anterior teeth are often immature permanent teeth. Considering the young age of the patients and ongoing dental development, a conservative approach is often preferred. Direct composite resin restorations offer a minimally invasive option that preserves as much tooth structure as possible. This conservative approach is particularly beneficial for young patients, because it allows for future treatment options and adaptation to growth-related changes in the dentition[8]. Furthermore, prioritizing crown prostheses for immature permanent teeth can negatively impact patients and guardians in terms of cost and time, and may be unnecessarily invasive. Therefore, direct composite resin restorations are often the first choice in children and adolescents[9,10]. Direct composite resin restorations for anterior teeth have evolved significantly over the past few decades. Improvements in material properties, including wear resistance, color stability, and bonding strength, have considerably improved their clinical performance[11]. Furthermore, advanced techniques such as layering and shading contribute to the improved aesthetic outcomes of these restorations[12]. Despite these advancements and the widespread use of direct composite restorations in pediatric dental trauma cases, research on their long-term efficacy is limited, and few patients are followed-up into adulthood. Therefore, clarifying the life span and factors affecting the survival rate of direct composite resin restorations is important. This study aimed to evaluate the long-term clinical survival rate of direct composite resin restorations in children and adolescents with anterior crown fractures and to provide crucial evidence to support or refine current treatment guidelines and inform clinical decision-making. Additionally, we aimed to evaluate whether direct composite resin restoration is appropriate as the primary treatment in various clinical conditions through survival analysis. Furthermore, we aimed to comprehensively evaluate factors that influence the success of direct composite resin restorations over time. This information is vital for optimizing treatment protocols, improving patient outcomes, and potentially reducing the need for more invasive procedures in the future.

Materials and Methods

1. Study subjects

This retrospective study was approved by the Medical Ethics Committee of Wonju Severance Hospital (CR324007). The study included children and adolescents who received direct composite resin restorations for anterior crown fractures due to trauma at Wonju Severance Hospital between March 2011 and February 2022. The patients were treated by 16 experienced dentists (11 pediatric dentists and 5 conservative dentists) using standardized techniques for direct composite resin restoration, and were followed up by one pediatric specialist and one conservative specialist. Dentists etched the dentin and enamel with 37% phosphoric acid, then treated them with etch-and-rinse adhesive systems (Adper™ Scotchbond™ 1 XT, 3M ESPE, St. Paul, MN, USA, SB1) according to the manufacturer’s instructions. Light-cured direct composite resin (Denfil Flow, Vericom Laboratories Ltd., Anyang, Korea) was used for restoration. Data from patients were collected according to the following criteria (Fig. 1). We included patients who received direct composite resin restoration for anterior crown fractures in permanent teeth caused by trauma. Patients who were aged 6 to 18 years and had been followed up for at least 12 months after the restoration were included. Among these patients, we excluded patients who did not return for follow-up after treatment, patients with inaccurate electronic medical records, and patients without available pre- and post-treatment radiographs. Additionally, we excluded patients who received treatments other than direct composite resin restoration and patients with physical or mental disabilities.

2. Study design

This study included 59 patients, and data regarding sex, age, history of pulp treatment, ratio of the resin restoration to the clinical crown, and restoration failure were extracted from the electronic medical records and radiographs. In this study, fracture or detachment of the direct composite resin restoration was classified as restoration failure. The restoration survival rate was analyzed by classifying participants into age groups of 6 - 8 years, 9 - 11 years, 12 - 15 years, and 16 - 18 years. Among teeth with pulp treatment, only those in which pulp treatment was started before completing the resin restoration were included in the analysis. The ratio of the resin restoration to the clinical crown was calculated by measuring the areas of the restoration site and clinical crown on periapical radiographs (Fig. 2). The radiographs before and after restoration were imported into Adobe Photoshop 2024 (version 25.0.0; Adobe Systems Inc., San Jose, CA, USA). The two images for each tooth were overlapped using the software, and the ratio of the resin restoration to the clinical crown was calculated to classify teeth into two groups. Group I included teeth with a restoration area ratio < 0.5, and Group II included teeth with a ratio ≥ 0.5.

3. Statistical analysis

Statistical analysis was performed using SPSS 25.0 (IBM Corp., Armonk, NY, USA). The relationships between the survival rate of direct composite resin restorations and age groups, sex, history of pulp treatment, and ratio of resin restoration to clinical crown were analyzed using chi-square tests and Fisher’s exact test. Long-term cumulative survival and survival rate were evaluated using the Kaplan-Meier product-limit estimator in SPSS and compared using the log-rank test. Factors associated with failure were evaluated using Cox regression analysis. This analysis assumes that observations within the same group are correlated and share the same frailty. Hazard ratios and their corresponding 95% confidence intervals were determined. Statistical significance was set at α = 0.05.

Results

This study included 86 direct composite resin restorations from 59 patients with anterior crown fracture. Of these, 25 restorations (29.06%) failed during the followup period. The follow-up period ranged from 12 to 132 months, and the mean follow-up duration was 45.88 ± 33.59. The Kaplan-Meier survival curve showed that the mean retention time was 88.65 ± 6.67 months (Fig. 3).

1. Survival rate according to patient age

The survival rates of direct composite resin restorations were 57.1% in 6 - 8 years, 69.4% in 9 - 11 years, 91.3% in 12 - 15 years, and 53.8% in 16 - 18 years (Table 1). Survival rates during the follow-up period were significantly different according to the patient’s age at the time of trauma (p= 0.036).

2. Survival rate according to sex

This study included 35 males and 24 females. Of the total 86 teeth, 53 teeth were included in 35 males and 33 teeth in 24 females (Table 2). The survival rate of direct composite resin restorations during the follow-up period was 73.1% and 67.6% in males and females, respectively. The survival rate during the follow-up period was not significantly different between the sexes (p= 0.632).

3. Survival rate according to pulp treatment

Of the 86 teeth included in the study, 29 had pulp treatment, and restoration failure occurred in 7 of them. In contrast, of the 57 teeth without pulp treatment, restoration failure occurred in 18 (Table 3). Survival rates during the follow-up period were not significantly different between teeth with and without pulp treatment (p= 0.617). Kaplan-Meier survival curves showed that the mean retention time in teeth with and without pulp treatment was 99.35 ± 9.98 and 79.68 ± 9.07 months, respectively. For teeth with pulp treatment, the 1 - and 3 - year cumulative survival rates were 89.2% and 84%, respectively. For teeth without pulp treatment, the 1 - and 3 - year cumulative survival rates were 94.4% and 78%, respectively. Similar to the statistical result from the chi-square test, there was no significant difference between both survival curves (p= 0.215, Fig. 4).

4. Survival rate according to the ratio of the resin restoration to the clinical crown

During the follow-up period, restoration failure occurred 23 out of 72 teeth in Group I and 2 out of 12 teeth in Group II (Table 4). There was no significant difference according to the ratio of the resin restoration to the clinical crown by the Fisher’s exact test (p= 0.334). Kaplan-Meier survival analysis showed that survival rates were not significantly different between the groups (p= 0.228). The mean retention time of Group I and Group II was 84.71 ± 7.30 and 83.11 ± 9.29, respectively. The 1- and 3-year cumulative survival rates in Group I and II were 92.9% and 80.4% and 100% and 77.8%, respectively (Fig. 5).

5. Survival rate according to variable associations

No significant associations were found between the independent variables (Table 5). Females had a 0.7-times lower survival probability compared to males. Teeth without endodontic treatment had 0.69 times lower chances of survival than teeth that underwent endodontic treatment. Regarding the groups, Group II had 1.2 times higher survival probability over time compared to Group I.

Discussion

The anterior teeth play a particularly important role in aesthetics, and fractures due to trauma can have undesirable physical, emotional, and mental effects on affected children. Therefore, fractures of anterior teeth require appropriate treatment[13].

Options for restoration of anterior crown fracture include direct composite resin restoration, fragment reattachment, and crown prostheses[14,15]. Fragment reattachment is useful for restoring the natural existing tooth shape and color; however, the patient must present with an intact fragment at the time of trauma. Although crown prostheses are generally indicated for retention and aesthetic purposes in cases of large fractures, crown prostheses for children and adolescents are challenging. Young permanent teeth in children are incompletely erupted and covered by the gums. Moreover, because they have not undergone attrition, the impression of the point angle is rounded and soft. Furthermore, immature permanent teeth have large pulp chambers compared to the tooth contour, and the pulp horns are protruding. Therefore, tooth preparation for crowns may cause hypersensitivity or pulp exposure. Additionally, crown prostheses performed during childhood and adolescence often require replacement due to aesthetic changes caused by growth.

In this study, 29.06% of direct composite resin restorations were failed during the follow-up period. This failure rate is slightly lower than those reported in previous studies, where failure rates ranging from 36.5% to 38% over similar follow-up periods were observed[16,17]. The difference in failure may be attributed to several factors. Firstly, the timing and criteria for assessing treatment outcomes varied between studies. Additionally, the follow-up durations were different for each study. Furthermore, unlike previous studies that primarily focused on adult populations, this study evaluated direct composite resin restorations in a diverse age group, including children and adolescents.

In this study, the survival rate of direct composite resin restorations was significantly different according to the patient’s age (p= 0.036). Notably, the 12 - 15 years showed the highest survival rate (91.3%), whereas the 6 - 8 and 16 - 18 years showed relatively lower survival rates (57.1% and 53.8%, respectively). These results provide interesting insights when considering the developmental stages of anterior teeth and the periods of high trauma risk. Anterior teeth generally erupt around 6 - 9 years of age, with root completion occurring around 9 - 11 years[18,19]. According to previous studies, dental trauma occurs most frequently in children and adolescents aged 8 - 10 years[20,21]. Other studies have reported that dental trauma occurs most frequently in children aged 10 - 12 years[22,23]. These findings suggest that most traumatized anterior teeth in children and adolescents are immature permanent teeth. The differences in survival rates according to age can be interpreted more meaningfully when considering this background. The low survival rate in the 6 - 8 years may reflect the difficulties in restoring teeth that are not fully erupted. In contrast, the high survival rate in the 12 - 15 years may be attributed to increased stability due to completion of root formation. The lower survival rate in the 16 - 18 years could be attributed to the higher severity of trauma in this age group or the influence of other factors such as increased occlusal forces[24]. These results suggest the need for age-based treatment approaches. Particularly in younger patients, more conservative and flexible treatment options may be necessary, along with continuous monitoring and additional interventions as required. Although these results show that direct composite resin restoration is a useful option for the treatment of immature permanent teeth, they emphasize the need for a cautious approach considering age-related risk factors.

In this study, the survival rate of direct composite resin restorations was not significantly different between the sexes (p= 0.632). This finding is consistent with previous studies that have reported no significant difference in the survival rates of anterior composite resin restorations between males and females[9,16]. These results support the rationale for choosing composite resin restorations for anterior crown fracture regardless of sex.

This study evaluated factors that could affect the survival rate of direct composite resin restorations. No significant difference in the survival rate of direct composite resin restorations according to the history of pulp treatment was observed (p= 0.617). Endodontically treated teeth have an increased risk of fracture due to reduced dentin moisture, loss of collagen cross-linking, and loss of coronal tissue connectivity and integrity due to pulp removal[25-27]. However, the resin core that is restored above the root canal filling material increases the surface area in which the bonding agent contacts. Moreover, the resin core adheres to the dentin and improves the overall retention of the resin restoration. Therefore, the presence of a resin core can contribute to increased retention and relatively compensate the risk of crown fracture in teeth with pulp treatment, similar to the better survival rate of post-based restorations[28]. Along with other factors, tooth structure weakening due to pulp treatment and increased retention due to the resin core may contribute to the lack of a significant difference in the survival rates of direct composite resin restorations between teeth with and without pulp treatment. This suggests that restoring the fractured anterior teeth with direct composite resin can be clinically acceptable, regardless of the history of pulp treatment. Based on the results of this study, no significant difference in survival rates according to the ratio of the resin restoration to the clinical crown was observed. This is inconsistent with the findings in previous studies in which larger resin restorations were subject to greater stress, leading to a higher risk of fracture[9,29]. However, recent advancements in composite resin materials and adhesive systems have greatly improved their mechanical properties, allowing them to withstand stress[30-32]. This improvement would be a factor in increasing survival rates for large restorations in this study. Additionally, in this study, experienced dentists performed the restorations using standardized techniques, which may have enabled high-quality restorations regardless of size. The expertise of the practitioners could have mitigated potential issues associated with larger restorations[33]. Furthermore, it is important to consider that the study evaluated children and adolescents. The teeth in children and adolescents have higher elasticity compared to those in adults, potentially helping to better absorb and distribute stress[34]. The combination of these factors might explain why restoration size did not significantly impact restoration survival in this study. However, an important limitation must be considered in interpreting the results of this study. Due to the lack of a sufficient sample size in this study, the number of patients in each group was not equal, which may have affected the results. If the number of patients in Group II had been similar to that in Group I, there might have been a significant difference in survival rates. Given this limitation, the results of this study should be interpreted with caution. Nevertheless, while there have been some recent studies on the survival rates of direct composite resin restorations of anterior teeth, few have provided valid research on survival rates based on the restoration size of direct composite resin[35-37]. Therefore, despite certain limitations, our finding that there was no significant difference in survival rates according to the resin restoration area could be a reasonable result. While additional studies with balanced sample sizes are necessary to confirm these results, this study offers valuable insights into the performance of recent resin restorations. Based on the findings in this study, direct composite resin restorations can be considered for treatment regardless of their size, particularly in children and adolescents.

This study had several limitations. First, this study was limited to a single medical institution, resulting in a small sample size. Second, this long-term survival rate study included restorative treatments performed by multiple dentists. Third, due to a lack of clinical photographs, the exact size of the fractured area and differences in retention due to the attachment area could not be evaluated.

Conclusion

This study demonstrated the clinical efficacy of direct composite resin restorations for traumatic anterior crown fractures in children and adolescents. The favorable 10 - year survival rate observed regardless of sex, history of pulp treatment, or the ratio of the resin restoration to the clinical crown suggests that composite resin restorations can be considered a primary treatment option for various clinical conditions.

NOTES

Conflicts of Interest

The authors have no potential conflicts of interest to disclose.

Fig 1.

Study flow.

Fig 2.

Ratio of the resin restoration to the clinical crown calculation. The ratio of the resin restoration was defined as the surface area of composite resin restoration divided by the whole clinical crown surface area.

Fig 3.

Kaplan-Meier survival curve of teeth evaluated in this study.

Fig 4.

Kaplan-Meier survival curve of teeth with pulp treatment and without pulp treatment. Both curves were not significantly different (p = 0.215).

Fig 5.

Kaplan-Meier survival curve of Group I and Group II. There was no significant difference in survival curve (p = 0.228).

Group I: ratio of the resin restoration to the clinical crown < 0.5; Group II: ratio of the resin restoration to the clinical crown ≥ 0.5.

Table 1.

Failure of the direct composite resin restoration according to age

	Patients	Tooth				Total	p value
		Failure		Success
		n	%	n	%
6 - 8	13	6	42.9	8	57.1	14	0.036^*
9 - 11	24	11	30.6	25	69.4	36
12 - 15	13	2	8.7	21	91.3	23
16 - 18	9	6	46.2	7	53.8	13
Total	59	25	29.1	61	70.9	86

p value from the independent Fisher’s exact;

* p < 0.05.

Table 2.

Failure of the direct composite resin restoration according to sex

	Patients	Tooth				Total	p value
		Failure		Success
		n	%	n	%
Male	35	14	26.9	38	73.1	53	0.632
Female	24	11	32.4	23	67.6	33	0.632
Total	59	25	29.1	61	70.9	86

p value from the independent chi-square test;

* p < 0.05.

Table 3.

Failure of the resin restoration according to the pulp treatment

	Tooth				Mean retention time (months ± SD)	Total	p value
	Failure		Success
	n	%	n	%
With pulp treatment	7	24.1	22	75.9	99.3 ± 9.9	29	0.617
Without pulp treatment	18	31.6	39	68.4	79.6 ± 9.0	57	0.617
Total	25	29.1	61	70.9		86

p value from the independent chi-square test;

* p < 0.05.

Table 4.

Failure of the resin restoration according to the ratio of the resin restoration to the clinical crown

	Tooth				Mean retention time (months ± SD)	Total	p value
	Failure		Success
	n	%	n	%
Group I	23	51.9	49	51.1	84.7 ± 7.3	72	0.334
Group II	2	14.3	12	85.7	83.1 ± 9.2	14	0.334
Total	25	29.1	61	70.9		86

p value from the independent Fisher’s exact;

* p < 0.05.

Group I: ratio of the resin restoration to the clinical crown < 0.5; Group II: ratio of the resin restoration to the clinical crown ≥ 0.5.

Table 5.

Hazard ratios (HR) for independent variables and survival rate of the direct composite resin restorations

Independent variables	HR (95% Cl)	p value
Sex
Male	1	0.393
Female	0.700 (0.309 - 1.587)
History of pulp treatment
With pulp treatment	1	0.421
Without pulp treatment	0.688 (0.277 - 1.708)
the ratio of the resin restoration to the clinical crown
Group I	1	0.770
Group II	1.206 (0.344 - 4.224)

p value from the independent Cox regression analysis;

* p < 0.05.

Group I: ratio of the resin restoration to the clinical crown < 0.5; Group II: ratio of the resin restoration to the clinical crown ≥ 0.5; Cl: confidence interval.

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