Bite Force Distribution and Occlusal Adjustment in Stainless Steel Crowns and BioFlx Crowns of Children Aged 4–8 Years

Abstract

Purpose

This study aimed to evaluate and compare occlusal adaptation and bite force distribution following the placement of stainless steel crowns (SSCs) and BioFlx crowns in children aged 4–8 years using the T-scan system.

Materials and methods

A randomized controlled clinical trial was conducted on 50 children requiring pulpectomy and crown restoration in primary molars. The participants were randomly assigned to receive either SSCs (n = 25) or BioFlx crowns (n = 25). Occlusal contacts and bite force parameters were recorded at three intervals: baseline (precementation), immediately postcementation, and at 2 weeks postplacement using the T-scan system. Statistical analysis was carried out using Friedman's test, Mann–Whitney U test, Cochran's Q test, and McNemar's test. A p-value < 0.05 was considered statistically significant.

Results

Both crown types initially disturbed occlusal equilibrium and bite force distribution immediately after placement. At the 2-week follow-up, the BioFlx group demonstrated significantly better occlusal adaptation, with a quicker return to baseline bite force values and fewer persistent premature contacts compared to the SSC group (p < 0.05). Older children (>7 years) showed faster occlusal adaptation in both groups, especially in the BioFlx group.

Conclusion

BioFlx crowns provided superior short-term occlusal adaptation and faster normalization of bite force distribution when compared to SSCs. Their flexibility and biocompatibility may contribute to enhanced patient comfort and rapid occlusal integration. The T-scan system served as a reliable tool for objectively assessing occlusal changes in pediatric restorative procedures.

How to cite this article

Singh T, Devashish, Kannan A, et al. Bite Force Distribution and Occlusal Adjustment in Stainless Steel Crowns and BioFlx Crowns of Children Aged 4–8 Years. Int J Clin Pediatr Dent 2026;19(2):145–149.

Introduction

The restoration of pulpectomized primary molars is a cornerstone of pediatric dentistry, crucial for preserving arch integrity, maintaining masticatory function, and ensuring esthetics in the developing dentition.¹ Premature loss of primary molars can lead to various complications, including space loss, malocclusion, and impaired chewing efficiency, thereby affecting a child's overall oral health and quality of life.² Therefore, selecting an appropriate restorative material that provides durable full coverage protection while facilitating optimal occlusal adaptation is paramount.

For decades, stainless steel crowns (SSCs) have been the gold standard for restoring severely compromised primary molars, particularly after pulpectomy. Their widespread use is attributed to their exceptional durability, cost-effectiveness, and ability to provide complete coronal coverage, effectively protecting the tooth from further degradation and bacterial ingress.³ However, SSCs present certain limitations, including their metallic appearance, which can be esthetically unappealing to both children and parents, and their inherent rigidity. This rigidity can lead to transient occlusal disturbances and a period of discomfort immediately following cementation, often necessitating occlusal adjustments to achieve proper bite alignment.⁴

In recent years, newer restorative options have emerged, offering alternatives to traditional SSCs. Among these, BioFlx crowns represent a significant innovation. These preformed crowns are fabricated from flexible, bioactive resin materials designed to mimic the natural resilience and translucency of tooth structure.⁵ Proponents of BioFlx crowns suggest that their flexibility allows for better marginal adaptation and a more physiological response to masticatory forces, potentially reducing occlusal discrepancies and enhancing patient comfort.⁶ Furthermore, some studies indicate that the bioactive properties of these crowns may contribute to improved gingival health and reduced plaque accumulation compared to SSCs.^7,8 The inherent flexibility of BioFlx crowns may also offer an advantage in accommodating the dynamic eruptive and occlusal changes characteristic of growing children.

Accurate assessment of occlusal contacts and bite force distribution is critical for evaluating the functional success of full coverage restorations. Digital occlusal analysis systems, such as the T-scan (Tekscan Inc., South Boston, MA, United States), provide real-time, objective data on occlusal contacts, force distribution, and premature contacts.^9,10 This technology allows for precise identification of occlusal interferences that may not be detectable with traditional articulating paper methods, offering a more comprehensive understanding of the masticatory system's response to restorative interventions.¹¹ While the pediatric masticatory system is known for its remarkable adaptability, even in the presence of minor occlusal interferences,¹² there remains a paucity of comparative data specifically evaluating the adaptation period and long-term functional outcomes of BioFlx crowns vs SSCs using objective digital analysis.

This study aims to address this critical gap in the literature by conducting a randomized controlled clinical trial to evaluate and compare the occlusal adaptation and bite force distribution following restoration with SSCs and BioFlx crowns in children aged 4–8 years. Utilizing T-scan analysis at multiple time intervals postinsertion, this research seeks to provide objective evidence to guide clinical decision-making and enhance patient outcomes in pediatric restorative dentistry.

Aims and Objectives

Primary Aim

To compare the occlusal adaptation and bite force distribution using T-scan in primary molars restored with SSCs vs BioFlx crowns following pulpectomy in children aged 4–8 years.

Objectives

• To evaluate the percentage of bite force on the restored tooth at baseline, immediate postinsertion, and at 2 weeks.

• To assess the presence and resolution of premature occlusal contacts over time.

• To analyze the influence of age and gender on occlusal adaptation and bite force distribution.

Materials and Methods

Study Design

This study was designed as a randomized controlled clinical trial. The protocol for this study received approval from the Institutional Ethics Committee and Declaration of Helsinki. Prior to participation, informed consent was obtained from the parents or legal guardians of all enrolled children.

Participants

Sample Size

A total of 50 healthy children, aged 4–8 years, were recruited for this study. The sample size was determined based on a power analysis to detect a significant difference in occlusal parameters between the two crown types.

Inclusion Criteria

Participants were selected based on the following criteria:

• Healthy children aged 4–8 years.

• Presence of a primary molar indicated for pulpectomy and subsequent full coverage crown restoration.

• Angle's class I molar relationship.

• Absence of parafunctional habits (e.g., bruxism) or temporomandibular joint (TMJ) disorders.

Exclusion Criteria

Children were excluded from the study if they presented with any of the following conditions:

• Systemic illness or special healthcare needs.

• Presence of malocclusion requiring orthodontic intervention.

• Nonrestorable primary molars or multiple carious teeth requiring extensive restorative treatment.

• Preexisting crowns or large restorations that could interfere with occlusal analysis.

Randomization and Group Allocation

Following eligibility assessment and informed consent, participants were randomly allocated into two groups using a computer-generated randomization sequence (e.g., block randomization with a block size of 4). The allocation was concealed from the clinicians performing the restorative procedures. The two study groups were:

• Group A (n = 25): Received SSCs.

• Group B (n = 25): Received BioFlx crowns.

Clinical Protocol

All clinical procedures were performed by a single experienced pediatric dentist to ensure standardization.

Pulpectomy Procedure

Standard pulpectomy procedures were performed on the indicated primary molars. This involved biomechanical preparation of the root canals using K-files (sizes #25− #30) to the appropriate working length. Following preparation, the canals were obturated with a calcium hydroxide/iodoform paste (Metapex, Meta Biomed Co., Ltd., Cheongju, Korea), ensuring complete filling of the root canal system.

Crown Preparation

Stainless steel crowns: For SSCs, a 1− 1.5 mm occlusal reduction was performed, followed by proximal slicing to create adequate interproximal clearance. The crowns were then adapted to the tooth using crimping pliers to ensure a snug fit at the cervical margin.

BioFlx crowns: For BioFlx crowns, a conservative 0.5− 1 mm occlusal reduction was performed. Unlike SSCs, crimping was not required due to the inherent flexibility and precontoured design of the BioFlx crowns.

Cementation

Both SSCs and BioFlx crowns were cemented using a conventional glass ionomer cement (GC Fuji I, GC Corporation, Tokyo, Japan) according to the manufacturer's instructions. Excess cement was meticulously removed after setting.

T-scan Analysis

Occlusal contacts and bite force distribution were objectively assessed using the T-scan III digital occlusal analysis system (Tekscan Inc., South Boston, MA, United States). This system provides real-time, dynamic occlusal data.

Assessment Parameters

The following parameters were recorded and analyzed:

• Bite force percentage: The percentage of total bite force exerted on the restored tooth relative to the entire dental arch.

• Premature contacts: Identification and quantification of occlusal contacts that occur before stable intercuspation.

• Force distribution: Analysis of the distribution of occlusal forces across the dental arches.

Time Points

T-scan recordings were performed at three distinct time points:

• T0 (baseline): Precementation, prior to any restorative intervention, to establish initial occlusal parameters.

• T1 (immediate postcementation): Immediately after crown cementation, to assess initial occlusal changes.

• T2 (2 weeks postcementation): At a 2-week follow-up visit, to evaluate short-term occlusal adaptation and resolution of initial discrepancies.

Procedure

For each recording, the child was seated upright in the dental chair with the Frankfort plane parallel to the floor. The T-scan sensor was individually calibrated for each patient. Three separate occlusal recordings were taken for each time point, and the average of these readings was used for analysis to ensure reliability.

Statistical Analysis

Descriptive statistics were calculated for all variables. For within-group comparisons across different time points, Friedman's test was employed. Between-group comparisons at each time point were performed using the Mann–Whitney U test. For categorical data, such as the presence or absence of premature contacts, Cochran's Q test and McNemar's test were utilized. A p-value of <0.05 (p < 0.05) was considered statistically significant.

Results

Demographics

A total of 50 children (25 in the SSC group and 25 in the BioFlx group) successfully completed the study. The mean age of the participants was 6.7 ± 1.2 years. The gender distribution was approximately equal across both groups, and no participants dropped out during the study period.

Bite Force Distribution

The mean percentage of bite force on the restored tooth at different time points for both groups is presented in Table 1 (Figs 1A to C and Figs 2A to C). At baseline (T0), there was no statistically significant difference in bite force distribution between the SSC and BioFlx groups (p = 0.62), indicating comparable initial occlusal conditions.

Table 1:

Comparative bite force distribution on restored tooth (mean ± SD, %) (Fig. 4)

Time point	SSC group (mean ± SD, %)	BioFlx group (mean ± SD, %)	p-value
T0 (baseline)	15.8 ± 5.1	16.2 ± 4.7	0.62
T1 (immediate post)	20.9 ± 6.3	17.2 ± 5.4	0.03*
T2 (2 weeks post)	17.1 ± 5.0	15.7 ± 4.2	0.18

*Statistically significant (p < 0.05)

Figs 1A to C:

Bite force distribution pre-op (SSC)

Figs 2A to C:

Bite force distribution post-op (SSC)

Immediately postcementation (T1), the SSC group exhibited a statistically significant increase in bite force on the restored tooth (mean ± SD: 20.9 ± 6.3%) compared to the BioFlx group (mean ± SD: 17.2 ± 5.4%) (p = 0.03). This suggests a greater initial occlusal interference with SSC placement.

At the 2-week follow-up (T2), the bite force values in both groups showed a trend toward normalization. While the SSC group's bite force decreased to 17.1 ± 5.0%, and the BioFlx group's decreased to 15.7 ± 4.2%, the difference between the groups at this time point was no longer statistically significant (p = 0.18). Notably, the BioFlx group demonstrated values closer to their baseline, indicating a quicker return to physiological bite force distribution.

Premature Occlusal Contacts

The prevalence of premature occlusal contacts at T1 and T2 for both groups is summarized in Table 2. Immediately postcementation (T1), both groups showed a high incidence of premature contacts, with no statistically significant difference between the SSC group (63%) and the BioFlx group (57%) (p = NS).

Table 2:

Prevalence of premature occlusal contacts (%) (Fig. 5)

Time point	SSC group (%)	BioFlx group (%)	p-value
T1 (immediate post)	63	57	NS
T2 (2 weeks post)	30	10	0.02*

*Statistically significant (p < 0.05)

However, at the 2-week follow-up (T2), a significant difference was observed. The BioFlx group demonstrated a substantially lower percentage of persistent premature contacts (10%) compared to the SSC group (30%) (p = 0.02). This indicates that BioFlx crowns facilitated a more effective and rapid resolution of initial occlusal interferences.

Age and Gender Influence

Analysis of age-related differences revealed that children older than 7 years demonstrated faster occlusal adaptation across both crown groups. This effect was particularly pronounced and statistically significant in the BioFlx group (p < 0.05). No statistically significant differences in occlusal adaptation or bite force distribution were observed based on gender.

Subjective Observations

Qualitative feedback from parents indicated that children in the SSC group reported more instances of initial discomfort and sensations of a “high point” immediately after crown placement. Conversely, the BioFlx group was associated with higher esthetic acceptance and greater overall comfort reported by both children and parents.

Discussion

The present randomized controlled clinical trial provides valuable insights into the comparative occlusal adaptation and bite force distribution following the restoration of pulpectomized primary molars with either SSCs or BioFlx crowns in children aged 4–8 years. Our findings demonstrate that while both full coverage restorations initially disrupt the delicate occlusal equilibrium, BioFlx crowns facilitate a more rapid and complete return to physiological occlusal function within the short-term observation period.

Consistent with previous literature,^4,13 our study confirms that the immediate postcementation period (T1) for both crown types is characterized by an increase in bite force on the restored tooth and a higher incidence of premature contacts. This initial disturbance is an expected physiological response to the introduction of a new restorative material into the occlusal scheme. However, the statistically significant difference observed at T1, with the SSC group exhibiting a greater increase in bite force, suggests a more pronounced initial occlusal interference associated with the rigid nature of SSCs (Figs 1B and 2B). This aligns with subjective reports of discomfort and “high points” from parents in the SSC group, as noted in our qualitative observations.

By the 2-week follow-up (T2), both groups showed a trend toward normalization of bite force, indicating the remarkable adaptability of the pediatric masticatory system (Figs 1C and 2C).¹² However, the BioFlx group demonstrated a significantly lower percentage of persistent premature contacts and bite force values closer to baseline, signifying a superior short-term occlusal adaptation. This rapid equilibration can be attributed to the unique material properties of BioFlx crowns (Figs 3A to C).

Figs 3A to C:

Bite force distribution 2 weeks post-op (SSC)

These crowns are composed of a flexible, biocompatible resin, often reinforced with glass fibers or bioactive fillers, resulting in a modulus of elasticity closer to that of natural dentin.^5,6 This inherent flexibility allows BioFlx crowns to flex slightly under masticatory load, accommodating minor occlusal discrepancies and facilitating a more harmonious integration into the existing occlusion without the need for extensive adjustments.^14,15 This contrasts with the rigid nature of SSCs, which transmit occlusal forces more directly to the underlying tooth and periodontium, potentially prolonging the adaptive phase.¹⁶

The strict inclusion criteria of our study, limiting participants to those requiring only a single crown restoration without additional fillings or active carious lesions, were crucial for minimizing confounding factors and ensuring the reliability of T-scan readings. The presence of existing restorations, proximal caries, or sharp cusp tips can introduce artifacts and lead to false-positive readings on the T-scan, thereby compromising the accuracy of occlusal force and contact distribution recordings.¹⁷

Our findings regarding age influence are consistent with existing pediatric bite force literature, which suggests that older children (above 7 years) possess enhanced neuromuscular coordination and more mature masticatory musculature, contributing to faster occlusal adaptation.¹⁸

The more pronounced and statistically significant faster adaptation observed in the BioFlx group among older children further underscores the synergistic effect of the crown's material properties and the child's developing oral motor skills. The absence of significant gender differences in occlusal adaptation aligns with previous research in this age-group.¹⁹

Clinical Implications

The results of this study carry several important clinical implications for pediatric dental practice:

• Crown selection: BioFlx crowns present a compelling alternative to traditional SSCs, particularly in situations where rapid occlusal adaptation, enhanced esthetics, and improved patient comfort are primary considerations. Their superior short-term occlusal integration may reduce the need for multiple postoperative adjustments and improve initial patient acceptance.

• Patient comfort and acceptance: The qualitative findings suggest that BioFlx crowns are associated with less initial discomfort and higher esthetic acceptance, which can significantly improve the overall patient and parent experience in pediatric restorative procedures.

• Objective occlusal assessment: The effective utilization of T-scan analysis in this study highlights its value as an objective, real-time tool for monitoring occlusal adaptation in pediatric restorative dentistry. Its ability to precisely identify and quantify occlusal interferences can guide clinicians in achieving optimal occlusal harmony postrestoration.

• Material properties: The study reinforces the importance of material properties in restorative dentistry. The flexibility and biocompatibility of BioFlx crowns appear to confer distinct functional advantages during the critical occlusal adaptation period.

Future Directions

While this study provides robust short-term comparative data, several avenues for future research are warranted.

• Longer-term studies: Future research should focus on longer-term comparative studies with larger sample sizes to evaluate the wear characteristics, durability, marginal integrity, and gingival health associated with both crown types over extended periods.

• Patient-reported outcomes: Incorporating more comprehensive patient-reported outcome measures (PROMs) and parental satisfaction surveys would provide a more holistic understanding of the impact of these restorations on children's quality of life.

• In-depth material analysis: Further in vitro and in vivo studies focusing on the specific bioactive properties of BioFlx crowns and their long-term effects on the surrounding oral environment are needed.

Conclusion

In conclusion, BioFlx crowns represent a promising and clinically effective alternative to SSCs for the restoration of pulpectomized primary molars in children. This study demonstrates their superior short-term occlusal adaptation, characterized by a quicker return to physiological bite force distribution and significantly fewer persistent premature contacts. Furthermore, BioFlx crowns offer enhanced patient comfort and esthetic appeal. While both materials are effective in restoring primary molars, the inherent flexible and potentially bioactive properties of BioFlx crowns appear to confer distinct functional advantages during the crucial initial adaptation period postrestoration. The integration of objective digital occlusal analysis, such as T-scan, is highly recommended as a standard adjunct in both pediatric restorative research and clinical practice to ensure optimal functional outcomes.

Fig. 4:

Bite force distribution (%)

Fig. 5:

Premature occlusal contacts