Linear interpolation error in measured surfaces in a dental erosion study

An overview of three-dimensional imaging devices in dentistry

OBJECTIVE

To review four types of three-dimensional imaging devices: intraoral scanners, extraoral scanners, cone-beam computed tomography (CBCT), and facial scanners, in terms of their development, technologies, advantages, disadvantages, accuracy, influencing factors, and applications in dentistry.

METHODS

PubMed (National Library of Medicine) and Google Scholar databases were searched. Additionally, the scanner manufacturers' websites were accessed to obtain relevant data. Four authors independently selected the articles, books, and websites. To exclude duplicates and scrutinize the data, they were uploaded to Mendeley Data. In total, 135 articles, two books, and 17 websites were included.

RESULTS

Research and clinical practice have shown that oral and facial scanners and CBCT can be used widely in various areas of dentistry with high accuracy.

CONCLUSION

Although further advancement of these devices is desirable, there is no doubt that digital technology represents the future of dentistry. Furthermore, the combined use of different devices may bring dentistry into a new era. These four devices will play a significant role in clinical utility with high accuracy. The combined use of these devices should be explored further.

CLINICAL SIGNIFICANCE

The four devices will play a significant role in clinical use with high accuracy. The combined use of these devices should be explored further.

Influence of Scanner Precision and Analysis Software in Quantifying Three-Dimensional Intraoral Changes: Two-Factor Factorial Experimental Design

BACKGROUND

Three-dimensional scans are increasingly used to quantify biological topographical changes and clinical health outcomes. Traditionally, the use of 3D scans has been limited to specialized centers owing to the high cost of the scanning equipment and the necessity for complex analysis software. Technological advances have made cheaper, more accessible methods of data capture and analysis available in the field of dentistry, potentially facilitating a primary care system to quantify disease progression. However, this system has yet to be compared with previous high-precision methods in university hospital settings.

OBJECTIVE

The aim of this study was to compare a dental primary care method of data capture (intraoral scanner) with a precision hospital-based method (laser profilometer) in addition to comparing open source and commercial software available for data analysis.

METHODS

Longitudinal dental wear data from 30 patients were analyzed using a two-factor factorial experimental design. Bimaxillary intraoral digital scans (TrueDefinition, 3M, UK) and conventional silicone impressions, poured in type-4 dental stone, were made at both baseline and follow-up appointments (mean 36 months, SD 10.9). Stone models were scanned using precision laser profilometry (Taicaan, Southampton, UK). Three-dimensional changes in both forms of digital scans of the first molars (n=76) were quantitatively analyzed using the engineering software Geomagic Control (3D Systems, Germany) and freeware WearCompare (Leeds Digital Dentistry, UK). Volume change (mm³) was the primary measurement outcome. The maximum point loss (μm) and the average profile loss (μm) were also recorded. Data were paired and skewed, and were therefore compared using Wilcoxon signed-rank tests with Bonferroni correction.

RESULTS

The median (IQR) volume change for Geomagic using profilometry and using the intraoral scan was -0.37 mm³ (-3.75-2.30) and +0.51 mm³ (-2.17-4.26), respectively (P<.001). Using WearCompare, the median (IQR) volume change for profilometry and intraoral scanning was -1.21 mm³ (-3.48-0.56) and -0.39 mm³ (-3.96-2.76), respectively (P=.04). WearCompare detected significantly greater volume loss than Geomagic regardless of scanner type. No differences were observed between groups with respect to the maximum point loss or average profile loss.

CONCLUSIONS

As expected, the method of data capture, software used, and measurement metric all significantly influenced the measurement outcome. However, when appropriate analysis was used, the primary care system was able to quantify the degree of change and can be recommended depending on the accuracy needed to diagnose a condition. Lower-resolution scanners may underestimate complex changes when measuring at the micron level.

Investigation into the validity of WearCompare, a purpose-built software to quantify erosive tooth wear progression

OBJECTIVES

The use of surface matching software with intraoral scanners is developing rapidly which increases the need for accessible, accurate and validated measurement software. This investigation compared the current gold-standard Geomagic Control software to a purpose-built software "WearCompare".

METHODS

Artificially created occlusal defects of a known size were created on 10 natural molar teeth scanned with a structured-light model-scanner (Rexcan DS2, Europac 3D, Crewe). The volume change, maximum profilometric loss and mean profilometric loss were obtained from both Geomagic Control (3D Systems, Darmstadt, Germany) and WearCompare (leedsdigitaldentistry.com). Duplicated datasets were randomly repositioned and re-alignment performed. The effect of the re-alignment was calculated by analysing differences between the known defect size and defect size after re-alignment using the same measurement metrics. Lastly, clinical wear measurements were compared on natural molar surfaces (n=60) over 6 months using study models collected from a previous longitudinal trial. Data analysis was performed in SPSS v25 (paired t-tests, Pearson correlations, p<0.05).

RESULTS

Measurement correlation between the softwares was greater than 0.97 (p<0.001) for all measurement metrics. The volume change error (SD) after alignment was -0.67mm³(1.14) for Geomagic and -0.06mm³(0.93) for WearCompare (p=0.140 and r=0.065, p=0.86). Measurement errors were observed after alignment in both softwares and no statistical differences were observed between softwares. The volume change on the clinical dataset over 6 months was +0.29 mm³(3.97) in Geomagic and -0.30mm³(1.82) for WearCompare (p=0.19 and r=0.61, p<0.001). The mean profile gain was 42.86μm(40.19) for Geomagic and 32.17μm(23.72) for WearCompare (p=0.048). Correlations between the softwares were greater than 0.6 for all measurement metrics except for mean profile gain.

SIGNIFICANCE

WearCompare is a comparable tool to Geomagic for quantifying erosive tooth wear. WearCompare reported statistically less profile gain indicating less error but further research is needed to reduce the human errors in both softwares.

3D Simulation Modeling of the Tooth Wear Process

Severe tooth wear is the most common non-caries dental disease, and it can seriously affect oral health. Studying the tooth wear process is time-consuming and difficult, and technological tools are frequently lacking. This paper presents a novel method of digital simulation modeling that represents a new way to study tooth wear. First, a feature extraction algorithm is used to obtain anatomical feature points of the tooth without attrition. Second, after the alignment of non-attrition areas, the initial homogeneous surface is generated by means of the RBF (Radial Basic Function) implicit surface and then deformed to the final homogeneous by the contraction and bounding algorithm. Finally, the method of bilinear interpolation based on Laplacian coordinates between tooth with attrition and without attrition is used to inversely reconstruct the sequence of changes of the 3D tooth morphology during gradual tooth wear process. This method can also be used to generate a process simulation of nonlinear tooth wear by means of fitting an attrition curve to the statistical data of attrition index in a certain region. The effectiveness and efficiency of the attrition simulation algorithm are verified through experimental simulation.