Ortho Insight 3D Research Articles

Comparing virtual setup software programs for clear aligner treatment.

The aim of this study was to compare the outcomes of the same amount of tooth movement among four different virtual setup software programs. This retrospective study included 32 patients who underwent Invisalign treatment. Patients' initial stereolithography (STL) files were imported to three different software programs (SureSmile Aligner [Dentsply Sirona, Charlotte, NC], Ortho Insight 3D [Motion View software, Chattanooga, TN], and Ortho Analyzer [3Shape, Copenhagen, Denmark]). After virtually moving teeth based on the numbers from ClinCheck Pro (Align Technology, Inc., Santa Clara, CA) tooth movement tables, final STL files were exported from all four software programs. ClinCheck Pro final STL files were used as references, while final STL files from the other software programs were used as targets. Superimpositions were performed between references and target STL files using Geomagic Control X software (3D Systems, Rock Hill, SC), and color-coded maps were obtained to illustrate potential differences. Intraclass correlation coefficient showed a high degree of reliability for repeated methodology (0.995-0.997). The differences among absolute averages (Abs Avg.), averages of positive values (+Avg.), and negative values (-Avg.) for both upper and lower models were significant among all software programs (ClinCheck Pro, SureSmile Aligner, Ortho Insight 3D, and Ortho Analyzer), for both upper and lower STL files, the smallest difference was found between ClinCheck Pro and SureSmile Aligner with a median of (0.03, 0.31, -0.19) mm for upper and (0.02, 0.29, -0.17) mm for lower STL files (Abs Avg., +Avg. and -Avg.), respectively. The biggest difference was found to be between ClinCheck Pro and Ortho Analyzer with a median of (0.05, 0.46, -0.45) mm for upper and (0.06, 0.48, -0.40) mm for lower STL files. There were no significant differences in the number of aligners per patient. Final outcomes of the same amount of tooth movement in four different software programs differed significantly. The number of aligners per patient remained unchanged.

Comparing 3D Tooth Movement When Implementing the Same Virtual Setup on Different Software Packages.

Background/objectives: The purpose of this study was to compare the differences in tooth movements when implementing the same virtual setup on the following four different software packages: ClinCheck® Pro, Ortho Analyzer®, SureSmile®, and Ortho Insight 3D®. Materials/Methods: Twenty-five adult patients treated with Invisalign® at the Case School of Dental Medicine (CWRU)’s department of orthodontics were retrospectively collected. Initial stereolithography (STL) files were obtained and imported into three software packages. The teeth were moved in order to replicate the virtual setup from ClinCheck® Pro. The final outcomes were exported from each software package. ClinCheck® Pro STL files were used as the reference while STL files produced by the other software packages were used as the targets. Best fit superimpositions were performed using Geomagic® Control X. Based on the results, tooth position was adjusted in the three software packages until the virtual setups from ClinCheck® Pro were replicated. Once confirmed, the tables containing the tooth movements were compared. The number of aligners and number of attachments automatically generated from each of the software packages were also evaluated. Results: Extrusion/intrusion (p ≤ 0.0001) and translation buccal/lingual (p ≤ 0.0004) were significantly different among the software packages. ClinCheck® Pro and SureSmile® (p ≤ 0.000), SureSmile® and Ortho Insight 3D® (p ≤ 0.014), SureSmile® and Ortho Analyzer® (p ≤ 0.009), and Ortho Insight 3D® and Ortho Analyzer® (p ≤ 0.000) generated a significantly different number of maxillary aligners. The results varied slightly for mandibular aligners, with only ClinCheck® Pro and Ortho Insight 3D® (p ≤ 0.000), SureSmile® and Ortho Insight 3D® (p ≤ 0.000), and Ortho Insight 3D® and Ortho Analyzer® (p ≤ 0.000) exhibiting a significant difference. ClinCheck® Pro and SureSmile® (p ≤ 0.000) differed significantly in the number of attachments produced. Conclusions: There are statistically significant differences in extrusion/intrusion, translation buccal/lingual, the number of aligners, and the number of attachments when implementing the same virtual setup on different software packages. Clinicians may need to consider this when utilizing software programs for digital diagnosis and treatment planning.

Dental arches in inherited severe isolated growth hormone deficiency

ObjectivesThe growth of the dental arches depends on GH and insulin-like growth factor type 1 (IGF1), but the consequences of GH deficiency (GHD) on their growth are still unclear, probably due to the acquired etiology of GHD in most described series, often associated with additional pituitary deficits (thyrotrophic, corticotrophic and gonadotrophic hormones), and imperfections of related replacement therapies, which may affect the dental arch growth. To avoid these limitations, we took advantage of a unique cohort of subjects with isolated GH deficiency (IGHD) due the same mutation in the GH releasing hormone receptor gene, living with very low serum GH and low to undetectable circulating IGF1 levels. Our purpose was to analyze the dimensions of maxillary and mandibular dental arches. Methods22 adult IGHD (15 untreated and 7 previously partially treated with GH) and 33 controls were enrolled in a cross-sectional study using the Ortho Insight 3D and MeshMixer software, ResultsIn untreated IGHD subjects all maxillary arch measures were smaller than controls, while among mandibular arches, only the mandibular canine width and the mandibular arch length were reduced. In partially GH treated subjects only the palate depth, the maxillary canine width, the maxillary and mandibular arch lengths remained smaller than controls. ConclusionsIGHD reduces the growth of maxillary arch to a greater degree than the mandibular arch, suggesting different control of superior and inferior dental arches. GH treatment increases some of these measures.

Correlation of two different measuring methods for digital models: Manual on printed paper and digital in computer: A retrospective study

Digital models are considered the new standard in the clinical practice of orthodontics. However, they are difficult to use in the absence of a true scale for chairside use during clinical appointments. Therefore, an easy standardized method with true-scale paper print images would be of great utility. The aim of this study was to correlate and compare measurements obtained manually in true-scale paper printed images of digital models with those obtained digitally in the computer. Sixty desktop scanned digital models (30 upper and 30 lower) were analyzed. Ortho Insight 3D software was used for generating the printed images on paper and for measuring the digital models. Intercanine width, interpremolar width (first and second), intermolar width (first), and arch length measures were performed with both methods and were correlated and compared. There was a high correlation between measurements performed with both methods. Values obtained from paper print images were lower and showed statistically significant differences (<0.4 mm; P < 0.001), which did not have any clinical implications. There is a high correlation between orthodontic measurements obtained manually in true-scale paper printed images of digital models and those obtained digitally in computer models, with no clinical differences between the two measurements. True-scale printed images of digital models can be used chairside in clinical appointments for the verification of measurements, or even as a guide for archwire individualization and shape bending without the need for long and complex processes or scale sizing adjustments.

Estimation of root inclination of anterior teeth from virtual study models: accuracy of a commercial software

BackgroundThe aim of the study was to assess the accuracy of commercially available software in estimating anterior tooth root inclination from digital impressions of the crowns of the teeth.Subjects and methodsFollowing sample size calculation and application of inclusion and exclusion criteria, 55 anterior natural teeth derived from 14 dry human skulls were selected. Impressions were taken and plaster study models were fabricated. Plaster models were scanned using the high-resolution mode of an Ortho Insight 3D laser scanner. The teeth on the digital scans were segmented and virtual roots were predicted and constructed by the Ortho Insight 3D software. The 55 natural teeth were removed from the dry skulls and scanned using the Identica extraoral white-light scanner in order to calculate their actual root angulation. The teeth were scanned twice, once to acquire the crown and the cervical part of the root, and a second time to acquire the remaining part of the root, including the apex. The two scanned segments were joined in software by superimposing them along their common part. The accuracy of the digital models generated by the Ortho Insight 3D scanner in predicting root angulation was assessed by comparing these results to the corresponding measurements of the 55 natural teeth. The long axes of the tooth models obtained from the software prediction and the scanning of the actual teeth were computed and the discrepancy between them was evaluated. The error of the methods was evaluated by repeating the measurements on 14 teeth and showed an acceptable range.ResultsThe predicted tooth angulation was found to differ significantly from the actual angulation, both statistically and clinically. The angle between the predicted and actual long axes ranged from 2.0 to 37.6°(average 9.7°; median 7.4°). No statistically significant difference was found between tooth categories.ConclusionsFurther investigations and improvements of the software are needed before it can be considered clinically effective.

A CBCT evaluation of root position in bone, long axis inclination and relationship to the WALA Ridge

Correct tooth position in all planes of space while respecting the boundaries of the underlying bone is important for stability of teeth after orthodontic treatment as well as the health of the supporting periodontium.1,2 The aim of this study was to determine: 1) if mandibular posterior teeth are more centered over basal bone when they are more upright or close to WALA Ridge norms proposed by Andrews3; 2) if mandibular posterior teeth are more centered in alveolar bone when they are more upright or close to the WALA Ridge norms; 3) if the estimated center of resistance mandibular posterior teeth is most often centered in alveolar bone; and 4) if the WALA Ridge is located at or near the estimated center of resistance of mandibular posterior teeth. A sample of 34 pre-treatment CBCT scans and mandibular casts of patients ages 12–18 were included in the study. CBCT scans were digitized and analyzed using the Carestream 3D Imaging Software Version 3.5.7. Casts were digitally scanned using the Ortho Insight 3D scanner. The WALA Ridge horizontal measurements were made using the Six Elements™ software (MotionView, Chattanooga, TN). The WALA Ridge vertical measurements were obtained from the casts using a digital caliper. Coronal CBCT images were used to measure tooth positions of pre-treatment mandibular posterior teeth relative to surrounding bone. Centeredness of teeth within the bone was quantified and compared to their inclination and to the WALA Ridge location: D1, D2, D3 and D4. Data were analyzed using the JMP version 10 SAS Software. Descriptive statistics were used to calculate the mean, standard deviation, minimum, and maximum values for the distance between WALA Ridge vertical and CR, D2, D3 and D4 for each of the posterior teeth. Single linear regression analysis was performed to evaluate the relationship between both the long axis inclination and WALA Ridge variables compared to the D1, D2, D3, variables. No statistical significance was found for centeredness of mandibular posterior teeth over basal bone when they were more upright or approached WALA Ridge norms. No statistical significance was found for centeredness of mandibular posterior teeth in alveolar bone when they were more upright or approached the WALA Ridge norms. Significant differences were found for the mandibular posterior teeth center of resistance being centered in the alveolar bone regardless of the long axis inclination or WALA Ridge norms (p-value <0.05). Significant differences were also found for the Wala Ridge being located at or near the center of resistance of mandibular posterior teeth (p-value <0.05). 1) More upright mandibular posterior teeth based on long axis inclination or mandibular posterior teeth more closely related to the WALA Ridge landmark are not more centered over basal bone. 2) More upright mandibular posterior teeth based on long axis inclination or teeth more closely related to the WALA Ridge landmark are not more centered in alveolar bone. 3) The center of resistance of all mandibular posterior teeth can most often be found in the center of the alveolar bone regardless of inclination. 4) The WALA Ridge is located at or near the center of resistance for all mandibular posterior teeth. 5) The WALA Ridge may be a useful landmark for customizing mandibular arch form if teeth are tipped to an upright position.

Overall and Anterior Tooth Size Ratios in a Group of Emiratis.

Objectives:The aims of this investigation in a group of Emiratis were (1) To study overall and anterior tooth size ratios in Class I normal occlusion, (2) To estimate overall and anterior tooth size ratios in different malocclusion groups, (3) To compare overall and anterior tooth size ratios in Class I normal occlusion with the Bolton standards, and (4) To determine the distribution of overall and anterior tooth size ratios ± 2 SD from Bolton mean values in all occlusion groups.Materials and Methods:In this cross-sectional investigation, consecutive patients’ files, including dental casts, were selected from the archives of orthodontic clinics of the Dubai Health Authority. The final sample was formed following the application of specific inclusion criteria. The sample consisted of 521 pairs of dental casts representing both sexes (males: 188; females: 333) and different malocclusion groups (Class I: 288; Class II: 110; Class III: 30) and Class I normal occlusion (93). The mean age of patients was 16.18y for Class I, 15.73y for Class II, 15.83y for Class III, and 16.55y for Class I normal occlusion. The dental casts were scanned and digitized by the first author using the Ortho Insight 3D laser scanner. Measurements were made regarding maxillary and mandibular sums of mesiodistal tooth dimension of the overall (6-6) and anterior (3-3) groups of teeth. Statistical analysis included descriptive statistics, paired t-test and Analysis of Variance (ANOVA). The level of significance was set at p<0.05.Results:There were statistically significant differences among malocclusion groups with regard to overall and anterior tooth size ratios. However, the comparison between the Class I normal occlusion group and the Bolton standards showed no statistically significant differences. Only five cases in Class II malocclusion presented an anterior tooth size discrepancy outside plus 2 SD from Bolton mean values and one case in Class I malocclusion presented with an overall tooth size discrepancy outside plus 2 SD from Bolton mean values.Conclusion:This study of the different occlusion groups of the Emirati sample concluded that (a) Class I normal occlusion cases presented similar overall and anterior tooth size ratios to Bolton standards; (b) Overall and anterior tooth size ratios among different malocclusion groups exhibited statistically significant differences; (c) Five cases in Class II malocclusion presented an anterior tooth size discrepancy outside plus 2 SD from Bolton mean values, and (d) One case in Class I malocclusion presented an overall tooth size discrepancy outside plus 2 SD from Bolton mean values.

Anterior teeth root inclination prediction derived from digital models: A comparative study of plaster study casts and CBCT images.

BackgroundTo assess the accuracy of digital models generated using commercially available software to predict anterior teeth root inclination characteristics and compare the results to relevant data obtained from CBCT images.Material and MethodsFollowing sample size calculation and after application of inclusion and exclusion criteria, pre-treatment maxillary and mandibular plaster models and the corresponding CBCT scans of 31 patients attending a private orthodontic clinic were selected. The subjects were 10 males and 21 females with age range 12 to 40 years. Plaster models were scanned using the high resolution mode of an Ortho Insight 3D scanner and CBCT scans were taken using a Kodak 9500 Cone Beam 3D System machine. The teeth on the digital scans were segmented and virtual roots were predicted and constructed by the Ortho Insight 3D software. The long axes of the predicted roots and the actual roots, as segmented from the CBCT images, were computed using best-fit lines. The inter-axis angle was used to assess error in root inclination prediction by the software. Mann-Whitney and Kruskal-Wallis tests were used. Intra-examiner error was evaluated using the Bland-Altman method.ResultsThe maximum disparity in angle between images derived from digital models and CBCT data was almost 40 degrees (upper left canine). The upper and lower canines produced the worst results, followed by the lower lateral incisors. The upper central incisors showed the best results, although the maximum angle of difference exceeded 20 degrees (with the median around 8 degrees).ConclusionsRoot morphology imaging prediction is not a primary function of this software and this study confirmed its limitation as a sole tool in routine clinical applications. At present these predictions cannot be considered accurate or reliable unless correlated clinically with a radiographic image. Key words:Digital models, CBCT, tooth root inclination prediction software.

Palatal and Alveolar Tissue Deficiency in Infants With Complete Unilateral Cleft Lip and Palate.

To investigate intrinsic palatal and alveolar tissue deficiency in patients with unilateral cleft lip and palate (UCLP) as compared to age-matched individuals without UCLP using surface area measurements on 3D scans of plaster casts. 22 maxillary casts of infants with UCLP from the Wyss Department of Plastic Surgery of NYU Langone Medical Center and 37 maxillary casts from infants without clefts from Sillman's longitudinal study were scanned by Ortho Insight 3D by Motion View Software, LLC (Chattanooga, TN) and measured using Checkpoint software (Stratovan, Davis, CA). The palatal and alveolar surface areas of each cast were measured. The most superior point of the alveolar ridge in front of the incisive papilla and the most superior point of each maxillary tuberosity were connected by a line that ran along the highest part of the alveolar ridge. This line was used to set boundaries for the palatal surface area measurements. The surface areas of greater and lesser segments were measured independently on UCLP casts. A total palatal surface area for the UCLP sample including width of the cleft gap was also measured. There was a statistically significant difference in surface area (P > .001) when we compared the UCLP area of the cleft segments alone with the non-cleft sample. There was a positive correlation (determine the statistical significance) between the surface area of the cleft segments and cleft gap. In addition, there was a statistically significant difference between UCLP plus cleft area and the non-cleft samples in surface area (P < .0001). An intrinsic palatal and alveolar tissue deficiency exists in patients born with UCLP. The amount of tissue deficiency for a patient with UCLP should be considered when developing and executing a patient-specific treatment plan.

Digital models: How can dental arch form be verified chairside?

ABSTRACTIntroduction: Plaster dental casts are routinely used during clinical practice to access maxillary dental arch form and assist on fabrication of individualized orthodontic archwires. Recently introduced, digital model technology may offer a limitation for the obtainment of a dental physical record. In this context, a tool for dental arch form assessment for chairside use is necessary when employing digital models. In this regard, paper print of the dental arch seems thus to be useful. Methods: In the present study, 37 lower arch models were used. Intercanine and intermolar widths and dental arch length measurements were performed and compared using plaster dental casts, digital models and paper print image of the models. Ortho Insight 3D scanner was employed for model digitalization. Results: No statistically significant differences were noted regarding the measurements performed on the plaster or digital models (p> 0.05). Paper print images, however, showed subestimated values for intercanine and intermolar widths and overestimated values for dental arch length. Despite being statistically significant (p< 0.001), the differences were considered clinically negligible. Conclusion: The present study suggests that paper print images obtained from digital models are clinically accurate and can be used as a tool for dental arch form assessment for fabrication of individualized orthodontic archwires.

Accuracy of Bolton analysis measured in laser scanned digital models compared with plaster models (gold standard) and cone-beam computer tomography images.

ObjectiveThe aim of this study was to compare the accuracy of Bolton analysis obtained from digital models scanned with the Ortho Insight three-dimensional (3D) laser scanner system to those obtained from cone-beam computed tomography (CBCT) images and traditional plaster models.MethodsCBCT scans and plaster models were obtained from 50 patients. Plaster models were scanned using the Ortho Insight 3D laser scanner; Bolton ratios were calculated with its software. CBCT scans were imported and analyzed using AVIZO software. Plaster models were measured with a digital caliper. Data were analyzed with descriptive statistics and the intraclass correlation coefficient (ICC).ResultsAnterior and overall Bolton ratios obtained by the three different modalities exhibited excellent agreement (> 0.970). The mean differences between the scanned digital models and physical models and between the CBCT images and scanned digital models for overall Bolton ratios were 0.41 ± 0.305% and 0.45 ± 0.456%, respectively; for anterior Bolton ratios, 0.59 ± 0.520% and 1.01 ± 0.780%, respectively. ICC results showed that intraexaminer error reliability was generally excellent (> 0.858 for all three diagnostic modalities), with < 1.45% discrepancy in the Bolton analysis.ConclusionsLaser scanned digital models are highly accurate compared to physical models and CBCT scans for assessing the spatial relationships of dental arches for orthodontic diagnosis.

Reliability and validity of intraoral and extraoral scanners.

BackgroundThis study evaluated the reliability and validity of one extraoral [Ortho Insight 3D™ (Motionview Software, Hixson, TN/USA)] and two intraoral [ITero™ (Align Technologies, San Jose, CA/USA) and Lythos™ (Ormco Corp., Orange, CA/USA)] scanners.MethodsFifteen dry human mandibles were scanned twice with each of the scanners, and digital models were generated. Five measurements were made on the dry mandibles and on each of the generated models, including intermolar width, intercanine width, posterior arch length, premolar crown diameter, and canine height. Systematic and random errors were evaluated based on replicate analyses. Differences were assessed using paired Student’s t tests.ResultsReplicate analyses showed statistically significant systematic errors for only one measure (intermolar width measured from Ortho Insight 3D scans). Measurements taken from all three scanners were highly reliable, with intraclass correlations ranging from .926 to .999. Method errors were all less than 0.25 mm (averaged ≈0.12 mm). Posterior arch length and canine height were significantly smaller when measured on the Ortho Insight 3D scans than when measured on the dry mandibles and significantly smaller than when measured from the ITero and Lythos models.ConclusionsWhile all three scanners produced reliable measures, Ortho Insight 3D systematically underestimated arch length and canine height.

Accuracy of digital American Board of Orthodontics Discrepancy Index measurements.

A digital analysis that is shown to be accurate will ease the demonstration of initial case complexity. To date, no literature exists on the accuracy of the digital American Board of Orthodontics Discrepancy Index (DI) calculations when applied to pretreatment digital models. Plaster models were obtained from 45 previous patients with varying degrees of malocclusion. Total DI scores and the target disorders were computed manually with a periodontal probe on the original plaster casts (gold standard) and digitally using Ortho Insight 3D (Motion View Software, Hixson, Tenn) and OrthoCAD (Cadent, Carlstadt, NJ). Intrarater and interrater reliabilities were assessed for 15 subjects using the Spearman rho correlation test. Accuracies of the DI scores and target disorders were assessed for all 45 subjects using Wilcoxon signed ranks tests. Intrarater and interrater reliabilities were high for total DI scores and most target disorders (r>0.8). No significant difference was found between total DI score when measured with OrthoCAD compared with manual calculations. The total DI scores calculated by Ortho Insight 3D were found to be significantly greater than those by manual calculation by 2.71 points. The findings indicate that a DI calculated by Ortho Insight 3D may lead the clinician to overestimate case complexity. OrthoCAD's DI module was demonstrated to be a clinically acceptable alternative to manual calculation of the total scores.

Comparison of 3-dimensional dental models from different sources: Diagnostic accuracy and surface registration analysis

The aim of this study was to assess the diagnostic accuracy and surface matching characteristics of 3-dimensional digital dental models obtained from various sources. Three sets of maxillary and mandibular digital models of 30 subjects were included in this study. Three-dimensional stereolithography model files were obtained from a 3-dimensional laser desktop scanner (Ortho-Insight 3D; Motionview Software, Hixson, Tenn), the emodel system (GeoDigm, Chanhassen, Minn), and cone-beam computerized tomography. Arch-length discrepancy measurements were made on the 3-dimensional digital models and compared with direct caliper measurements. Additionally, stereolithography files from the 3 digital model systems were paired and superimposed using a best-fit algorithm. Average linear differences between the stereolithography shells were computed together with surface correlation amounts at various tolerance levels. Data were evaluated using intraclass correlation coefficients and the Tukey mean difference test. Although all 3 digital model groups displayed good correlation with caliper measurements, the virtual scan models had the highest correlation with the manual method (ICC> 0.95). The Tukey mean difference test showed no consistent bias of one approach vs the others compared with caliper measurements; random errors were detected in all the comparisons. For the estimation of arch-length discrepancy, the mean bias of the scanned virtual models in comparison with caliper measurements (0.24 ± 0.67 mm) was smaller than the mean biases of the emodels and the models generated from cone-beam computed tomography. Additionally, the best surface overlap correlation was observed between the virtual scanned models and the emodels. The mean linear distances between the stereolithography shells of these 2 model systems were 0.14 and 0.13 mm for the maxillary and mandibular arches, respectively. All 3 digital model systems can provide diagnostic information similar to caliper measurements, with varying degrees of agreement limits. The scanned virtual models had the least mean bias. A strong surface match correlation was observed between the virtual scanned models and the emodels, indicating that these could be used interchangeably.

Accuracy of laser-scanned models compared to plaster models and cone-beam computed tomography

To compare the accuracy of measurements obtained from the three-dimensional (3D) laser scans to those taken from the cone-beam computed tomography (CBCT) scans and those obtained from plaster models. Eighteen different measurements, encompassing mesiodistal width of teeth and both maxillary and mandibular arch length and width, were selected using various landmarks. CBCT scans and plaster models were prepared from 60 patients. Plaster models were scanned using the Ortho Insight 3D laser scanner, and the selected landmarks were measured using its software. CBCT scans were imported and analyzed using the Avizo software, and the 26 landmarks corresponding to the selected measurements were located and recorded. The plaster models were also measured using a digital caliper. Descriptive statistics and intraclass correlation coefficient (ICC) were used to analyze the data. The ICC result showed that the values obtained by the three different methods were highly correlated in all measurements, all having correlations>0.808. When checking the differences between values and methods, the largest mean difference found was 0.59 mm±0.38 mm. In conclusion, plaster models, CBCT models, and laser-scanned models are three different diagnostic records, each with its own advantages and disadvantages. The present results showed that the laser-scanned models are highly accurate to plaster models and CBCT scans. This gives general clinicians an alternative to take into consideration the advantages of laser-scanned models over plaster models and CBCT reconstructions.

Predicting tooth-size discrepancy: A new formula utilizing revised landmarks and 3-dimensional laser scanning technology

The goal of this study was to develop a more accurate formula to forecast tooth-size discrepancies in patients based on not only the size of the whole teeth but also functional arch components derived from normal cusp-fossa interdigitation that should be obtained as the final treatment goal. A total of 141 dental casts from Dr Larry Andrews' collection of "normal occlusions" that never received orthodontic treatment were scanned with an Ortho Insight 3D Laser Scanner (Motion View Software, Chattanooga, Tenn). Individual tooth sizes and portions of tooth sizes were measured with the Motion View Software. For each set of models, potential tooth-size discrepancies were calculated by using both the original Bolton analysis and the new Johnson/Bailey analysis developed by this team at the University of California at San Francisco (UCSF). Six tooth-size discrepancy ratios were computed and included the Bolton (2) and the new (4) Johnson/Bailey analysis ratios for the anterior arch component, posterior arch component, and overall ratio of the maxillary and mandibular arches. The Johnson/Bailey analysis utilized different landmarks and groups of teeth. It consequently divided the maxillary segment by the mandibular segment, in contrast to the Bolton ratios, which divided the mandibular sums by the maxillary totals. The Bolton anterior segment ratio ranged from 70.68 to 84.81, with a mean of 77.91 (SD, 2.43) (3.1%). The Bolton overall ratio ranged from 86.19 to 96.62, with a mean of 91.64 (SD, ±1.74) (1.8%). The Johnson/Bailey posterior discrepancy ratio ranged from 0.98 to 1.23, with a mean of 1.10 (SD, ±0.04) (3.6%). Its anterior discrepancy ratio ranged from 0.91 to 1.14, with a mean of 1.03 (SD, ±0.04) (3.9%). The Johnson/Bailey overall discrepancy ratio ranged from 0.98 to 1.15, with a mean of 1.06 (SD, ±0.03) (2.8%). Two methods were used to forecast tooth-size discrepancies between opposing arches in a sample with clinically acceptable occlusions. The new approach provided more specific ratios utilizing more clinically relevant functional archcomponents derived from dental cusp-fossa interdigitation.