Measurement of the Occlusal Splint Wear using Computer-Aided Design Software: A Dental Technique

ABSTRACT

Objective:  To describe a technique used to measure wear on the surface of occlusal splints using dental Computer-Aided Design (CAD) software.

Material and Methods:  The technique employs intuitive CAD software (Exocad), which features innovative tools capable of providing qualitative analysis and quantitative data regarding wear and structural modifications of occlusal splints in patients with sleep bruxism. The workflow for file acquisition and wear evaluation is described as follows: Digitization of occlusal splints; Importation of STL files; Initial mesh alignment; Automated superimposition of STL files; Assessment of mesh agreement degree.

Results:  The technique enabled the quantitative analysis of the wear on the occlusal surface of the splints. After the superimposition of the standard tessellation language (STL) files of the splints with and without wear, the CAD software displayed the chromatic deviations that indicated areas of thickness reduction. The highest degrees of wear were observed in the anterior guidance and posterior contact areas. This wear pattern provided evidence of the different muscle activity behaviors associated with the bruxism, including predominantly eccentric movements in the anterior region and centric forces in the posterior region.

Conclusion:  Dental CAD software can be utilized as a viable complementary tool to identify the thickness of occlusal splints after adjustments and, consequently, diagnose the severity level of sleep bruxism, providing predictable treatment and effective patient management during clinical follow-up visits.

Keywords:
Bruxism; Computer-Aided Design; Dimensional Measurement Accuracy; Occlusal Splints.

Introduction

Occlusal splints are interocclusal removable devices used for occlusal stabilization and muscular reprogramming that affect the fitting between the jaws or tooth-to-tooth contact [¹,²]. In dental practice, this non-invasive therapy has been frequently applied to manage Temporomandibular Joint Disorders (TMJD) [³,⁴] and to protect teeth from excessive occlusal forces arising from tooth grinding or clenching among patients suffering from sleep bruxism [⁵,⁶].

Typically, heat-cured Polymethyl Methacrylate (PMMA) based occlusal splints exhibit acceptable mechanical properties regarding durability and wear resistance and, thus, are more suitable for bruxism treatment and patient groups that require long-term therapies [⁷]. However, the excessive load and wear of the occlusal surface of teeth during sleep bruxism lead to ongoing loss of resin surface in oral appliances, and consequently, deformation and thickness reduction [⁸]. Bruxism is an unconscious occlusal habit of dysfunctional rhythmic activity characterized by clenching and grinding of the teeth [⁹].

Quantifying the wear is a paramount evaluation to ensure the effectiveness, longevity, and safety of the sleep bruxism treatment. The wear of occlusal splints' materials over time is a concern in clinical practice due to the risk of complications, such as occlusal contact imbalance and fracture of these dental appliances [¹⁰]. Previous studies have investigated the dental materials and methods for wear testing of occlusal devices, considering several protocols [¹⁰-¹⁴]. A clinical trial evaluated the wear behavior of occlusal splints over a 3-month follow-up period, demonstrating similar rates regardless of the material [¹⁵]. Oppitz et al. [¹⁶] reported higher wear rates for mixed occlusal stabilization splints compared with rigid splints. Conventional assessment of wear on the surface of occlusal splints is limited and imprecise, as it relies on a subjective clinical approach using tactile and visual methods, with the aid of carbon paper and a caliper to identify signs of wear, deformation, or thickness reduction. However, the authors are unaware of digital techniques that have measured the wear of the occlusal splints in the clinical context.

Standardization of the measurement protocols and wear testing in vivo is essential to provide accurate and reliable evaluation regarding the longevity and effectiveness of the occlusal splints. Identifying the wear parameters that are clinically meaningful using area, volume, and depth is a key factor in determining the selective adjustments of the occlusal surface or the need for replacement of the occlusal splints, ensuring a solid and effective treatment [¹⁷]. Given the relevant achievement of detailed information about the amount of wear of occlusal splints, this dental technique presents a reliable, foreseeable, and intuitive workflow that can be conducted by both experts and non-experts, by optimizing the steps of adjustments, qualitative and quantitative evaluation of sleep bruxism activity. The technique may also be applied to occlusal devices and dental prostheses manufactured using different dental materials, including milled, 3D-printed, or heat-cured polymerizing resin, by digital and conventional workflows.

Technique

The technique utilizes intuitive Computer-Aided Design (CAD) software (Exocad GmbH, Darmstadt, Germany), which comprises innovative tools capable of providing qualitative analysis and quantitative data regarding the wear and structural modifications of occlusal splints in patients with sleep bruxism. An occlusal device is fabricated by the milling technique, and a total of two standard tessellation language (STL) files are required to conduct this dental technique. The workflow for the attainment of files and wear evaluation is described as follows:

1. Using a desktop scanner (Autoscan-DS-EX, Shining 3D Tech Co Ltd., Zhejiang, China), digitize both occlusal splints without adjustments (before delivery) (Figure 1A) and after verifying the occlusal contacts using a carbon-paper (Accu Film^®, Parkell Inc.Brentwood, NY, USA) (Figures 1B and 1C). A non-aqueous matt white spray (Metal-Chek D7, Bragança Paulista, SP, Brazil) was applied to assist 3D scanning because is challenging for the scanners to digitize reflective property materials (Figures 2A and 2B).

Figure 1
Occlusal splints. A, Occlusal surface view (prior delivery). B, Occlusal contacts recorded with carbon paper before delivery. C, Occlusal contacts recorded with carbon-paper after occlusal splint wear.

Figure 2
Occlusal splint after adjustment, showing wear on the surface. A, Occlusal splint after adjustment. B, Occlusal splint adapted to the initial scanning position.

2. Import the STL files of the occlusal splints (STL1 and STL2) into CAD software (Exocad GmbH, Darmstadt, Germany) (Figure 3A).

Figure 3
Acquisition and superimposition of STL files. A. Importation of STL files for CAD software. B, Selection of 4 points on the surface of occlusal splints (1 and 2 in the anterior region; 3 and 4 in the posterior region). C, Alignment of STL files (1 and 2 in the anterior region; 3 and 4 in the posterior region).

3. Navigate the alignment tools in the Exocad design software. Then, select 4 points in the occlusal surface of the device, considering 2 points in the anterior region (canine guide) and the other 2 points in the posterior region (molar teeth) (Figures 3B and 3C).

4. Provide the prompt for automated superimposition of the STL files using self-alignment tools in the CAD software (Figure 4A). The software works based on the improved adjustment method, aligning the entire occlusal surface. To ensure the proper alignment, coronal slices are made considering the segmentation areas in the position of the anterior and posterior teeth (Figure 4B).

Figure 4
Agreement level between the meshes. A, Qualitative measurement of mandibular excursive movements over the splint. B, Quantitative measurement of occlusal splint thickness loss.

5. Evaluate the agreement degree of the meshes considering the color gradient scale (Figure 4B). The color gradient scale ranges from blue (minimum values) to pink (maximum values) and states the surface wear of the occlusal splints in the anterior and posterior regions. So, color strips closer to blue imply a higher level of agreement between the meshes and non-wear in the areas, while color strips closer to pink indicate greater gaps and wear.

Discussion

Teeth clenching and grinding interfere with the equilibrium of occlusal contacts; therefore, splint therapy is essential to reduce the intensity of pain and symptoms of muscle tenderness [⁹]. The wear of occlusal splints adversely influences their longevity and can compromise the treatment outcomes. In this context, this study described a dental technique based on digital technology to measure the occlusal splint thickness after adjustment or regular use considering the color gradient scale. Measuring the wear loss using intuitive dental CAD software is a straightforward and reliable procedure that allows dental clinicians to associate the intensity level of sleep bruxism activity and the severity of occlusal splint wear. Based on this, the professional can define proper treatment plans and patient management in the recall appointments.

With advances in the Computer-Aided Design and Manufacturing (CAD-CAM) system, different approaches have been utilized to replicate and measure the wear loss of occlusal devices, including 3D scanning, accuracy, manufacturing process, and material’s mechanical properties. Grymak et al. [¹³] conducted a systematic review that evaluated the behavior of various materials and methods used for wear testing of the occlusal splint and their antagonists. The findings demonstrated similarity between the conventional and digital occlusal splints regarding the wear; however, the results remain inconsistent because of a wide variety of testing protocols and no standardization considering the occlusal force, polishing standards previously to testing, and the antagonist.

Several techniques for imaging wear measurement of occlusal splints or removable dental prostheses have been stated, considering the advanced metrology tools. In this context, Geomagic software emerges as a method used for assessing the volumetric wear loss of the occlusal splint surface [¹⁵,¹⁸-²⁰]. Although effective for surface image comparison, the software features a complex interface, the handling of tools by clinical or technical professionals still depends on a learning curve, and the high licensing fees present a further hurdle to widespread adoption.

For this study, the Exocad software was used to evaluate the wear of occlusal splints, providing a more simplified, user-friendly, and accessible approach. Exocad is widely recognized for its intuitive interface and powerful tools, enabling the precise and customized creation of removable devices. This dental technique streamlines the evaluation process, representing a significant clinical advancement by integrating design and analysis within a single platform, thereby enhancing efficiency, accuracy, and accessibility in digital dental practices.

Moreover, the described technique offers advantages because enables determining the region of the higher incidence of bruxism regarding the muscle contraction activity. Coronal slices are made, and the measurement of the wear is displayed. The depth of the wear observed in this technique is comparable with a tactile method performed by Huettig et al. [²¹] The wear on the incisive edges, particularly in the canine guide, results in the prevalence of isotonic muscle activity, jeopardizing the idea of occlusal splint orientation and disregarding the principle of the mutually protected occlusion. On the other hand, damage in the posterior zone is associated with masticatory muscles and temporomandibular joint activities creating the continuous pressing of the teeth that can lead to fractures because the layer thickness of the occlusal surface is critically reduced [⁹]. Furthermore, it improves the predictability of clinical performance of the occlusal splints regardless of the dental materials, affording assessment of structural integrity and the survival of the intraoral appliances.

Challenges addressed in this technique included digital workflow to manufacturing and processing of the occlusal splint, and 3D scanning for acquisition of the STL files. Moreover, other limitations included the availability of the design CAD software that requires a license key and the need for an operator with expertise in the software tools. Although scanners are capable of digitizing most objects easily, in this study the application of a powder spray was required to mitigate reflectivity. Reproducing coatings with regular thickness remains a challenge, and the application of each layer should be meticulously controlled when using the scanning spray to ensure accurate and reliable results. Clinical studies with long-term follow-up are recommended to evaluate the accuracy of the technique considering several dental CAD systems.

Conclusion

This dental technique described how to measure occlusal splint wear by superimposing the STL files using a desktop scanner. Dental CAD software can be utilized as a viable complementary tool to identify occlusal splint thickness after adjustments and, consequently, diagnose the severity level of sleep bruxism, providing predictable treatment and patients’ management in the recall clinical visits.

• 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
  12 Jan 2026
• Date of issue
  2026

History

• Received
  15 Jan 2025
• Reviewed
  21 Apr 2025
• Accepted
  24 Apr 2025