Pediatric Patient Experience: Conventional versus Digital Impressions in a Crossover Randomized Trial

ABSTRACT

Objective:  To compare digital impression with the traditional method in 6-year-old children, evaluating preference, comfort, and the time required for each technique.

Material and Methods:  A randomized, controlled, single-center crossover trial was conducted with 32 six-year-old children. Digital impressions were taken with a scanner, and conventional impressions were taken with alginate, with a 1-week interval between procedures. During each procedure, impression time data were recorded, and upon completion, data on comfort and method preference were collected. For statistical analysis, Pearson's chi-square test was used, followed by a paired Student's t-test or the nonparametric Wilcoxon test, with α=0.05.

Results:  Intraoral scanners offer a more pleasant experience for pediatric patients, with a significant reduction in discomfort, such as gag reflex and fear. 96.9% of the children preferred digital impressions, while only 3.1% preferred conventional impressions (p = 0.000). The average time for digital impressions was 128.2 ± 12.4 seconds, compared to 202.1 ± 10.8 seconds for conventional impressions, a highly significant statistical difference (p = 0.000).

Conclusion:  Digital impressions obtained with an intraoral scanner are an effective and promising alternative to conventional methods, especially in pediatric patients.

Keywords:
Pediatric Dentistry; Dental Impression Materials; Child.

Introduction

Dental impressions have been used since the 18th century, when Phillip Pfaff first described the procedure. They are essential for recording intermaxillary relationships and fabricating various dental appliances [¹]. In adults, this is considered a routine procedure, but it is quite different in children. Taking dental impressions in pediatric patients is a significant challenge for the dentist [²,³], as it involves various reactions that complicate the procedure, such as the gag reflex, fear, crying, and limb movement [⁴]. Furthermore, the child's perception of the professional treating them can increase or decrease these reactions [⁵,⁶]. The presence of materials in the child's oral cavity can lead to these complications [⁷], underscoring the need to develop procedures that reduce operational time and complexity.

Technological advancements have enabled the development of intraoral scanners, which offer a promising alternative compared to conventional impressions [⁸,⁹]. Intraoral scanning devices were introduced for dental use in the 1970s [¹⁰]. Currently, intraoral scanners represent an alternative to conventional dental impression methods in children, offering several advantages, including a more pleasant patient experience, greater accuracy, and a more efficient surgical workflow [¹¹-¹³]. In the literature, several studies have compared conventional impressions with digital impressions [¹⁴-¹⁶], but these studies have been conducted on adult patients.

Today, impression-taking remains a procedure that elicits rejection and discomfort among patients in general, with pediatric patients particularly susceptible to discomfort or fear during dental surgery. Given that children have different sensitivity to stimuli than adults, and that reproducing smaller oral structures can be complex, it is essential to conduct a study evaluating children's perceptions during dental impression procedures. For this reason, the present study was designed to investigate and compare the efficacy of conventional impressions with that of digital impressions in six-year-old children, based on comfort, preference, and time required during the procedure. Given the theoretical framework, we hypothesize that digital impressions in children are more effective than conventional dental impressions.

Material and Methods

Study Design and Ethical Clearance

This is a crossover, randomized, controlled, and monocentric trial. The experimental design followed the CONSORT guidelines for reporting clinical trials and the extended checklist for crossover randomized trials. The study protocol was approved by the Research Ethics Committee of the Faculty of Dentistry at the National University of Trujillo (P.I.B. EST. 06 - 0021 - 2023). Informed consent was obtained in writing from the parents and/or legal guardians of the children.

Participants and Cases

The children included in the study were students from a private school located in the city of Trujillo, La Libertad, Peru. Sample size was calculated based on an infinite population formula with a 95% confidence level, 80% power, and a standard deviation of 70 seconds, as described by Yilmaz and Aydin [¹⁷] to detect a minimum difference of 50 seconds in impression-taking time between both groups, resulting in a total of 31 children. Participation was invited from the first two grade levels in primary education, yielding a list of 43 students. The partial sample consisted of 35 patients, as 3 children did not have their parents' or guardians' informed consent signed, and 5 children did not meet the selection criteria. Three male children were randomly selected from the study to achieve gender balance, resulting in a final sample of 32 participants (16 boys and 16 girls).

Simple random sampling was conducted, applying the selection criteria to include those children aged 6 years with no history of digital or conventional impression-taking, no temporomandibular discomfort, no craniofacial anomalies, and whose parents or guardians had signed the informed consent. Children who could not undergo behavior management, had a history of dental anxiety, exhibited a hyperactive gag reflex, or declined to participate in the study were excluded.

Interventions

The process of selecting the study sample and distributing interventions is illustrated in Figure 1. All patients in the sample were assigned consecutive numbers and a study information sheet. To avoid bias from execution order, simple randomization was used to determine whether conventional impression-taking or intraoral scanning would be performed first.

Figure 1
Flow diagram of the study sample selection process and distribution of interventions.

For the conventional impression-taking using alginate, the child was correctly positioned in the dental unit, the impression tray was selected, and the alginate Tropicalgin Extra Fast (Zhermack SpA, Badia Polesine, Italy) was prepared using a semi-automatic technique with a mechanical mixer Alghamix II (Zhermack SpA, Badia Polesine, Italy) (Figure 2).

Figure 2
A. Conventional impression-taking, B. Digital impression-taking, C. Patient smiling upon completing both procedures, D. Delivery of clinical reports, scanning images, and plaster models from the procedures performed.

For digital impression-taking with an intraoral scanner, the child was correctly positioned at the dental unit, and the impression was captured with the Aoralscan 3 (SHINING 3D Dental, Hangzhou, China). The entire surface of the upper arch was scanned, following the procedure as the scan progressed (Figure 2).

Impression-taking in the children started according to their assigned group. After the first dental impression, a 7-day waiting period was observed before proceeding with the second impression. During the process, data on impression time and total procedure time were recorded, and once the impression was completed, data on comfort and preference for the methods were noted. At the end of the study, the parents of each child were provided with the clinical findings, such as the odontogram and gingival indices, as well as the images obtained from the intraoral scanner and the plaster model obtained from the conventional impression, to which a Carrea Analysis was applied to assess the symmetry of the upper arch (Figure 2).

Randomisation

On the first day, the order of the two main procedures (digital or conventional impression of the upper arch) was determined by simple randomization, such that 16 subjects received the conventional impression method as their first impression, and 16 received the digital impression with the Shining 3D Dental - Aoralscan 3 as their first impression. The method was carried out through a simple drawing to decide who would start with the conventional method and who with the digital method.

Statistical Method

The collected data were processed automatically using IBM SPSS Statistics 26 (IBM Corp., Armonk, NY, USA). To compare the two impression techniques, the chi-square test was employed; to evaluate differences between groups according to scores, the Student's t-test for related data was applied; and, as an alternative, the nonparametric Wilcoxon test was used. Statistically significant differences were considered when the probability of error was less than 5% (p < 0.05).

Results

It was reported that 90.6% of the children considered digital impressions effective, whereas only 3.1% considered conventional impressions effective, showing a statistically significant difference (p=0.000) (Table 1).

Table 1
Efficacy of digital impressions and conventional impressions in children.

Efficacy	Type of Impression				p-value
	Digital		Conventional
	N	%	N	%
Effective	29	90.6	1	3.1	0.000
Not Effective	3	9.4	31	96.9

Regarding comfort, among males, 87.5% felt comfortable with the digital impression, compared with 62.5% with the conventional impression. Among females, 100% felt comfortable with the digital impression, while only 43.7% felt comfortable with the conventional impression (Table 2). Digital impressions were reported as the preferred method, with a 96.9% acceptance rate (Table 2). Finally, significant differences (p=0.000) were found in impression working time, with a shorter average time for digital impressions than for conventional impressions. The test confirms this disparity, showing a statistically significant difference in average partial impression time and total procedure time (Table 2).

Table 2
Comfort, preference, and time of digital impressions and conventional impressions in children, by sex.

Comfort	Male				Female				Total
	Digital		Conventional		Digital		Conventional		Digital		Conventional
	N	%	N	%	N	%	N	%	N	%	N	%
Comfortable	14	87.5	10	62.5	16	100.0	7	43.8	30	93.8	17	53.2
Tolerable	2	12.5	4	25.0	0	0.0	6	37.5	2	6.2	10	31.2
Uncomfortable	0	0.0	2	12.5	0	0.0	3	18.7	0	0.0	5	15.6
p-value	0.221				0.002				0.000
Preference
Preferred	15	93.8	1	6.2	16	100.0	0	0.0	31	96.9	1	3.1
Not Preferred	1	6.2	15	93.8	0	0.0	16	100.0	1	3.1	31	96.9
p-value	0.018				0.004				0.000
Time	$$\overline{x}\pm SD$$		$$\overline{x}\pm SD$$		$$\overline{x}\pm SD$$		$$\overline{x}\pm SD$$		$$\overline{x}\pm SD$$		$$\overline{x}\pm SD$$
Partial	67.9 ± 13.0		126.3 ± 8.9		69.9 ± 8.9		126.4 ± 10.7		68.6 ± 11.0		126.4 ± 9.7
p-value	0.000				0.000				0.000
Total	126.6 ± 12.8		200.2 ± 10.4		129.8 ± 12.1		204.0 ± 11.2		128.2 ± 12.4		202.1 ± 10.8
p-value	0.000				0.000				0.000

Discussion

In recent years, digital impression-taking has become increasingly popular, proving highly useful across dental specialties such as orthodontics, oral rehabilitation, and pediatric dentistry. However, research on digital impressions has predominantly been conducted with adult patients, with very few studies involving child patients, despite the significant proportion of orthodontic and pediatric patients being children and/or adolescents. The present study included a sample of 32 six-year-old children and reported a notable advantage of digital impressions over conventional impressions with alginate in terms of comfort, preference, and time.

The children indicated that impressions made with digitalization were significantly more comfortable than those made with conventional alginate methods, yielding results similar to those reported in the literature [⁴,¹⁵,¹⁸,¹⁹]. These results may be related to the fact that digital impressions are much less invasive than the conventional alginate impression technique, and the absence of alginate-filled impression trays led to a lack of gag reflex, respiratory difficulties, or pain. A previous study [²⁰] found a preference for conventional alginate impressions, likely due to less advanced intraoral scanner technology at the time. The use of cheek retractors and powder in that study may also have contributed to patient discomfort. Currently, this technique is no longer used.

Regarding preference, the children chose digital impressions over conventional alginate impressions, with results similar to those of other investigations [⁴,¹⁵,¹⁸]. These results relate to the comfort children experienced and their perception of reduced time in the dental chair. It is also noteworthy that studies evaluating preference for impression methods were predominantly conducted with adults, in contrast to the present study, underscoring the importance of considering age as a decisive factor when comparing results across studies. This is because children have much smaller mouths, making impressions more challenging. Moreover, adults are accustomed to impression-taking, whereas children view it as new.

In terms of time, both the partial impression time (or actual impression time) and the total procedure time were studied. For partial time, the digital impression demonstrated the best timing, a result similar to that of Yilmaz and Aydin [¹⁷]. However, for strict timing purposes, Yilmaz and Aydin [¹⁷] reported nearly one additional minute for both conventional and digital impressions, compared with the authors' findings in the present study. This discrepancy arises from differences in research procedures, as studies do not follow a standardized protocol for impression-taking and time measurement, leading to variations in results [²¹]. Yilmaz and Aydin [¹⁷] used Hydrogum 5 alginate (Zhermack) and the manual mixing technique.

In contrast, the authors of the present study used Tropicalgin ExtraFast alginate (Zhermack SpA, Badia Polesine, Italy), which has a shorter intraoral time and a shorter gelation time. Additionally, the mixing technique employed was semi-automatic with a mechanical mixer (Alghamix II - Zhermack SpA, Badia Polesine, Italy). Both factors contributed to the difference in time observed between the two studies.

In the present study, digital impression-taking had the best working time. The literature does not reach consensus on which technique offers the best timing, as some report the conventional alginate technique as more advantageous [¹⁸,¹⁹], while others favor digital impressions [⁴,¹⁵,¹⁷,²⁰]. However, for strict timing purposes, reported times (in minutes or seconds) differ across studies. This relates to the fact that both the software and hardware of intraoral scanners used for digital impressions are continually improved and updated; furthermore, the operator's experience also influences this variable. Thus, finding equal or "standardized" times across all studies is difficult, even when using the same intraoral scanner system. Therefore, the time reported in the literature is influenced by the time or period during which each study was conducted.

Finally, regarding efficacy, digital impressions showcased a significant advantage over conventional impressions. The literature does not report studies that have directly evaluated this variable, but its dimensions have been assessed. It is demonstrated that the most effective impression technique for treating children is digital impression-taking supported by an intraoral scanner.

The study has some limitations that should be considered when interpreting its results. First, the small sample size (n=32) and the inclusion of only six-year-old children limit the generalizability of the findings to other age groups in the pediatric population. Furthermore, the lack of a standardized protocol for measuring impression time may explain the variations observed compared with other published studies.

It is recommended that multicenter clinical trials with larger sample sizes and a wider age range be conducted to validate the results and establish uniform protocols for measuring impression time and accuracy. The development of intraoral scanners tailored to pediatric patient anatomy is necessary. Finally, integrating digital impressions and training in digital technologies into dental education will help consolidate the transition towards more precise and efficient pediatric dentistry, focused on a positive patient experience.

Conclusion

The present research suggests that digital impression-taking with an intraoral scanner is an effective and promising alternative to conventional impression methods for pediatric patients. Intraoral scanners provide a more pleasant patient experience, significantly reduce discomfort, and simplify clinical procedures. However, they also present some limitations that must be taken into account, such as the learning curve, cost, and access to the technology. Further large-scale clinical studies are required to evaluate the long-term performance of this technology in pediatric dentistry.

• 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
  27 July 2026
• Date of issue
  2026

History

• Received
  11 June 2025
• Reviewed
  20 Nov 2025
• Accepted
  05 Dec 2025