Influence of scanning protocol on the accuracy of complete-arch digital implant scans: An in vitro study.

OBJECTIVE: This in-vitro study assessed the influence of two intraoral scanning (IOS) protocols on the accuracy (trueness and precision) of digital scans performed in edentulous arches. METHODS: Twenty-two abutment-level master casts of edentulous arches with at least four implants were scanned repeatedly five times, each with two different scanning protocols. Protocol A (IOS-A) consisted of scanning the edentulous arch before inserting the implant scan bodies, followed by their insertion and its subsequent digital acquisition. Protocol B (IOS-B) consisted of scanning the edentulous arch with the scan bodies inserted from the outset. A reference scan from each edentulous cast was obtained using a laboratory scanner. Trueness and precision were calculated using the spatial fit analysis, cross-arch distance, and virtual Sheffield test. Statistical analysis was performed using generalized estimating equations (GEEs). Statistical significance was set at α = .05. RESULTS: In the spatial fit test, the precision of average 3D distances was 45 µm (±23 µm) with protocol IOS-A and 25 µm (±10 µm) for IOS-B (p < .001), and the trueness of average 3D distances was 44 µm (±24 µm) with protocol IOS-A and 24 µm (±7 µm) for IOS-B (p < .001). Cross-arch distance precision was 59 µm (±53 µm) for IOS-A and 41 µm (±43 µm) for IOS-B (p = .0035), and trueness was 64 µm (±47 µm) for IOS-A and 50 µm (±40 µm) for IOS-B (p = .0021). Virtual Sheffield precision was 286 µm (±198 µm) for IOS-A and 146 µm (±92 µm) for IOS-B (p < .001), and trueness was 228 µm (±171 µm) for IOS-A and 139 µm (±92 µm) for IOS-B (p < .001). CONCLUSIONS: The IOS-B protocol demonstrated significantly superior accuracy. Placement of scan bodies before scanning the edentulous arch is recommended to improve the accuracy of complete-arch intraoral scanning.

Comparison of maxillary transversal changes between auxiliary beta-titanium expansion arch and miniscrew-assisted rapid palatal expansion.

OBJECTIVE(S): This study compared buccal bone thickness, dental inclinations and maxillary transverse width dimensions changes between auxiliary beta-titanium expansion arch (AEA) and miniscrew-assisted rapid palatal expansion (MARPE). MATERIALS AND METHODS: The sample consisted of 29 patients, aged between 18 and 40 years, with transverse maxillary deficiency and treated without extractions, divided into two groups: group AEA: comprised 13 individuals (initial mean age: 29.23 ± 9.13 years) treated using auxiliary beta-titanium expansion arch; group MARPE: comprised 16 patients (initial mean age: 24.92 ± 7.60 years) treated with miniscrew-assisted rapid palatal expansion. Buccal bone thickness, dental inclinations and transverse width dimensions (dental, nasal base and jugular) were measured in cone-bean computed tomographies at pre- and post-treatment stages. The variables were compared using the independent t-test. RESULTS: The buccal bone thickness was similar for both groups at the post-treatment stage. The second premolars were significantly more buccal inclined in the AEA group and the right maxillary first molars in the MARPE group. The intercanine and intermolar distances were statistically significantly greater in the MARPE group. Changes in dental arch transverse dimensions were significantly greater for the MARPE group. CONCLUSION: Both treatment protocols corrected the maxillary transverse discrepancy; however, MARPE provided greater correction.

[Radiological assessment of long-term outcomes of restorative treatment in patients with shortened dental arches]. / Rentgenologicheskaya otsenka otdalennykh rezul'tatov ortopedicheskogo lecheniya patsientov s ukorochennym zubnym ryadom.

BACKGROUND: Restoring the integrity of the dentition with orthopedic structures should be carried out strictly according to indications, taking into account the condition of the supporting teeth and/or teeth limiting the defect. OBJECTIVE: To conduct a retrospective analysis of the results of orthopedic treatment of patients with shortened dentition according to clinical and radiological methods. MATERIALS AND METHODS: The material for the study was data from cone beam computed tomography (CBCT) of 126 patients with shortened dentition (most patients with the absence of a second molar, as well as the absence of the first and second molars), who sought a consultation about missing teeth in the orthopedic and surgical department of the Federal State Budgetary Institution National Medical Research Center TsNIISiCHLKh Ministry of Health of Russia. RESULTS: At the stages of treatment for patients in the study group, insufficient attention is paid to the restoration of terminal defects of the dentition in the upper and lower jaws, especially the restoration of second molars. This may be due to improper planning of dental treatment and insufficient motivation of the patient to carry out comprehensive dental rehabilitation. According to CT studies, the number of complications of orthopedic treatment in the area of supporting teeth and/or teeth limiting the included defect or terminal defect of the dentition in the masticatory region increases depending on the period of use of the orthopedic structure. CONCLUSIONS: The use of cantilever structures leads to functional overload of the supporting teeth. Neglecting the restoration of a full dentition and prosthetics of end defects of the dentition leads to dentoalveolar advancement of antagonists of missing teeth and the appearance of complications such as functional overload of supporting teeth and resorption of alveolar bone.

[The use of fixed expanders with orthodontic miniscrews support in children with mesial occlusion]. / Ispol'zovanie nes"emnykh rasshiritelei s vnutrikostnoi oporoi u detei s mezial'noi okklyuziei.

OBJECTIVE: Prevention of the development of pronounced skeletal abnormalities in patients with mesial occlusion. MATERIALS AND METHODS: Biometric analysis of control and diagnostic models of dentition was performed in 60 patients with dental anomalies before and after treatment in 3 mutually perpendicular planes to identify violations in the formation of dental arches by sagittal and transversal dimensions, and alveolar processes - by vertical dimensions (methods of A. Pont, G. Korkhaus). Measurements of 23 parameters of TRG and sections of CBCT were carried out using the modified Nad-Ars technique with analysis of skeletal parameters before and after treatment. Treatment was carried out using dilators for the upper jaw in combination with a facial mask and further dynamic observation using active retention devices. RESULTS: The results of treatment showed an increase in the length of the anterior segment of the upper dental arch by 2.8±0.55 mm (p<0.05 mm); expansion in the area of temporary molars by 2.85±0.65 mm (p<0.05); in the area of permanent molars by 2.75±0.55 mm (p<0.05); in the area of the apical basis of HF by 3.82±0.45 mm (p<0.05). The length of the lower dental arch in the anterior segment has not changed. Analysis of TRG parameters showed a significant increase in the values of

Influence of arch location and scanning pattern on the scanning accuracy, scanning time, and number of photograms of complete-arch intraoral digital implant scans.

OBJECTIVES: To measure the influence of arch location and scanning pattern on the accuracy, scanning time, and number of photograms of complete-arch implant scans acquired using an intraoral scanner (IOS). MATERIALS AND METHODS: A maxillary (maxillary group) and mandibular (mandibular group) model with 6 implant abutments on each cast was digitized using a desktop scanner (control scans). Six subgroups were created based on the scanning pattern used to acquire the scans using an IOS (Trios 4): occluso-buccal-lingual (OBL subgroup), occluso-linguo-buccal (OLB subgroup), bucco-linguo-occlusal (BLO subgroup), linguo-buccal-occlusal (LBO subgroup), zigzag (ZZ subgroup), and circumferential (C subgroup). The control scans were used as a reference to measure the discrepancy with the experimental scans calculating the root mean square error. Two-way ANOVA and the pairwise comparison Tukey tests were used to analyze the data (α = .05). RESULTS: Significant discrepancies in trueness (p < .001), precision (p < .001), scanning time (p < .001), and number of photograms (p < .001) were found. The maxillary group obtained poorer trueness and precision values, higher scanning times, and a larger number of photograms than the mandibular group. The C subgroup obtained the best trueness and precision values, but was not significantly different from the OLB, BLO, and LBO subgroups. The ZZ subgroup obtained the worst trueness and precision values (p < .05). The C subgroup obtained the lowest scanning time and number of photograms (p < .05). CONCLUSIONS: Arch location and scanning pattern influenced scanning accuracy, scanning time, and number of photograms of complete-arch implant scans.

Accuracy and eligibility of Bonwill⁃Hawley arch form established by CBCT image for dental crowding measurement: a comparative study with the conventional brass wire and caliper methods.

OBJECTIVES: The purpose of this study was to develop a novel Bonwill⁃Hawley method (Bonwill⁃Hawley arch form based on CBCT image) for the assessment of dental crowding, and to investigate and compare the accuracy and eligibility with the conventional brass wire and caliper methods under different crowding conditions. MATERIAL AND METHODS: Sixty patients with the pair of plaster casts and CBCT data were collected. All the casts were marked and transformed into digital models using iTero scanner, and imported into OrthoCAD software to measure the required space. Using the conventional brass wire (M1) and caliper methods (M2), the available space and dental crowding were measured and calculated basing on digital models, respectively. Correspondingly, the axial planes in the level of dental arches were oriented and captured from the CBCT images to draw the Bonwill⁃Hawley arch forms (M3), which were used to measure and calculate the available space and dental crowding. For each method, intra and inter-examiner reliabilities were evaluated with intra-class correlation coefficients (ICCs). Wilcoxon test and Kruskal-Wallis test were performed for statistically analyzing the discrepancy among different groups. RESULTS: Both intra- and inter-examiner reliability were generally excellent for all parameters obtained by the three methods, except for the dental crowding measured using M1(ICC: 0.473/0.261). The dental crowding measured using M2 were significantly increased in mild, moderate and severe-crowding groups compared with M1. However, no significant difference was detected between M1 and M3 in severe-crowding group (maxilla, p = 0.108 > 0.05; mandible, p = 0.074 > 0.05). With the deterioration of crowding condition, the discrepancy of dental crowding between M1 and M2, or M1 and M3 were significantly decreased (maxilla, M2-M1, mild VS serve, p = 0.003 < 0.05; maxilla, M3-M1, mild VS serve, p = 0.003 < 0.05; mandible, M2-M1, mild VS serve, p = 0.000 < 0.001; mandible, M3-M1, mild VS serve, p = 0.043 < 0.05). CONCLUSION: Dental crowding measured using the novel Bonwill⁃Hawley method was relatively greater than the caliper method, but not exceeding the brass wire method, which wound gradually come close to the brass wire method with the deterioration of crowding condition. CLINICAL RELEVANCE: The Bonwill⁃Hawley method basing on CBCT image proved to be a reliable and acceptable choice for orthodontists to analyze the dental crowding.

Three-dimensional relationship between the degree of bilateral impacted mandibular third molars angulation and the mandibular dental arch parameters: a cross-sectional comparative study.

OBJECTIVE: The purpose of this study was to three-dimensionally evaluate the relationship between the degree of bilateral impacted mandibular third molar (IM3M) angulation and the mandibular dental arch parameters in normal skeletal and dental malocclusion patients. MATERIALS AND METHODS: In this retrospective cross-sectional comparative study, 120 adult subjects' cone-beam computed tomography (CBCT) images were three-dimensionally analyzed. The sample included 120 adults aged 20-30 years, with a gender distribution of 51 male and 69 female participants. The sample was divided into 100 adults with bilateral IM3M (study group) and 20 adults with normal bilateral erupted M3M (control group). The study group was sub-divided into three groups according to the degree of IM3M buccolingual angulation (BL°): group A, < 12° on the center of the ridge (N = 30), group B, 12-24° off-center of the ridge (N = 40), group C, > 24° off-center of the ridge (N = 30). The study group was also sub-divided into two groups according to IM3M mesiodistal angulation (MD°): group 1 from 10 to 45° (N = 36), group 2 > 45° (N = 64). Comparison within and between groups was performed using one-way ANOVA followed by Tukey's post hoc test. The correlation between IM3M, BL, and MD angulation and the mandibular arch parameter was calculated using Pearson's correlation coefficient. RESULTS: Statistically significant differences (P < 0.001) were found between the IM3M BL° and anterior teeth inclination, arch length (AL), and inter-second molar width (inter 2nd MW) as well as between the IM3M MD° with anterior crowding and the arch length (P < 0.001). A significant positive correlation was found between IM3M BL° and anterior teeth inclination and between IM3M MD° and anterior teeth crowding and inter 2nd MW. A significant negative correlation was observed between IM3M BL° and inter 1st MW and 2nd MW. CONCLUSION: The degree of buccolingual and mesiodistal angulation of the impacted mandibular third molars was related with mandibular dentoalveolar changes. Increased buccolingual angulation is generally associated with increased anterior teeth inclination and decreased 1st and 2nd inter-molar width. The increase in mesiodistal angulations was generally related with increased anterior teeth crowding and 2nd inter-molar width. CLINICAL RELEVANCE: Assessment of the relationship between the impacted mandibular third molars and the degree of arch discrepancy, and the position of mandibular incisors in the three planes of space might help in the decision-making process for the extraction of the impacted third molars in adult patients.

Feasibility of using an intraoral scanner for a complete arch digital scan, part 2: A comparison of scan strategies.

STATEMENT OF PROBLEM: Various strategies for intraoral scanners (IOSs) can be used to scan the oral cavity. However, research on the scan range that can be clinically is lacking. PURPOSE: The purpose of this in vitro study was to compare the 3-dimensional (3D) distortion of complete arch scans as part of the scan strategy and analyze the clinically recommended scan range. MATERIAL AND METHODS: A computer-aided design (CAD) reference model was obtained with an industrial scanner. A CAD test model was obtained by using 6 IOSs (TRIOS2, TRIOS3, CS3500, CS3600, i500, and Primescan) to apply 2 scan strategies and 2 dental laboratory scanners (DOF and E1) (N=15). All the teeth were segmented in the reference model by using 3D inspection software (Geomagic control X). The 3D analysis was performed by aligning the test model to the reference model and evaluating the root mean square values of all segmented teeth. The Mann-Whitney U-test was performed for a statistical comparison of the 2 scan strategies (α=.05), the Kruskal-Wallis test (α=.05) was used to compare the scanners, and the Mann-Whitney U-test and Bonferroni correction method were used as post hoc tests (α=.0017). RESULTS: The 8 scanners obtained significant differences in the root mean square values of all teeth (P<.001). The root mean square value of IOSs increased from the left maxillary second molar to the right maxillary second molar. The difference in the 2 scan strategies showed different patterns depending on the IOS. CONCLUSIONS: Scan strategy 2 improved the accuracy of the IOSs. TRIOS2 and CS3500 are for single crowns; TRIOS3, CS3600, and i500 are for short-span prostheses; and Primescan is for long-span prostheses.

Accuracy of photogrammetric imaging versus conventional impressions for complete arch implant-supported fixed dental prostheses: A comparative clinical study.

STATEMENT OF PROBLEM: Clinical studies on the accuracy of the photogrammetric imaging technique for complete arch implant-supported fixed dental prostheses are lacking. PURPOSE: The purpose of this clinical study was to evaluate the accuracy (trueness) of photogrammetric imaging for complete arch implant-supported prostheses by comparing photogrammetric imaging with verified conventional splinted impressions. MATERIAL AND METHODS: Completely edentulous arches with at least 4 implants were included. Both photogrammetric imaging and conventional splinted impressions were performed in each jaw. The conventional casts were verified and scanned by using a laboratory scanner as the control. The distances and angulations between different implants (interimplant distances and interimplant angulations) were measured in all photogrammetric and conventional standard tessellation language (STL) files by using a reverse-engineering software program. The distance deviations between the photogrammetric and conventional impressions of the same participant were calculated as the primary outcome, and the angular deviations were obtained as the secondary outcome with descriptive analyses. The comparison between distance deviations and the clinically acceptable level of deviations (150 µm) was conducted by using the 1-sample t test. The effect of interimplant distances, interimplant angulations, and jaw (maxilla or mandible) on deviations was analyzed by using the Spearman correlation analysis, Kruskal-Wallis test, or Student t test, depending on the type of data (α=0.05 for all tests). RESULTS: Fourteen edentulous jaws were included. The overall distance deviation of photogrammetric imaging was 70 ±57 µm, significantly lower than the clinically acceptable level of misfit (150 µm; P<.001). The overall angular deviation was 0.432 ±0.348 degrees. The distance deviations were correlated with interimplant distances with a correlation coefficient (r) of 0.371 (P=.002). Interimplant angulation was not correlated with distance or angular deviations (P=.914, P=.914). Jaw was not correlated with distance or angular deviations either (P=.190, P=.209). CONCLUSIONS: The accuracy (trueness) of photogrammetric imaging of complete arch implant-supported prostheses was within a clinically acceptable range of errors. Distance deviations increased with greater interimplant distances. Interimplant angulations and jaw (maxilla or mandible) had no significant effect on the accuracy of photogrammetric imaging.

Maxillary dimensions and arch shape with palatally displaced canines.

BACKGROUND/OBJECTIVES: The aim of this study was to explore the effect of palatally displaced canines on maxillary dimensions and arch shape. METHODS: Occlusal and skeletal landmarks were plotted on cone beam computed tomography (CBCT) images of 156 orthodontic patients: 78 with palatally displaced canines (PDC) (27 left, 28 right, and 23 bilateral) and 78 controls using Mimics™ (Materialise, Belgium). Arch forms were created, and arch width, depth, and skeletal dimensions were measured. T-test (P < 0.05) was used to compare the groups. Geometric Morphometrics (GM) analysis was used to compare the groups and to explore the pattern of covariation between two sets of landmarks. RESULTS: The unilateral PDC group showed an increased first premolar, second premolar, molar widths, and an increased molar depth. No significant difference was found in arch form. The skeletal measurements were generally larger in the PDC group, but the transverse measurements were the most significant. Discriminant Function Analysis (DFA) with cross-validation allowed an accurate classification of 85.9% of the control group and 66.7% of the PDC group. The Mahalanobis distance displayed significant differences among three combinations of groups. Strong covariance was found between the second premolar and all other landmarks. LIMITATIONS: The small sample sizes of the stratified groups precluded recognition of statistical significance. CONCLUSIONS: Patients with unilateral PDC displayed significantly wider first, second premolar, and first molar widths, and increased first molar depths. There were no significant differences in arch form; however, GM showed significant differences between the groups and a prominent covariance function for the 2nd premolars.

Assessment of early dental arch growth modification with removable maxillary expansion by cone-beam computed tomography and lateral cephalometric radiographs: a retrospective study.

BACKGROUND: This study evaluated the skeletal and dental changes of patients brought by early removable maxillary expansion (ERME) treatment to explore the clinical treatment effect of ERME on early dental arch growth modification. METHODS: Subject children aged 6-10 years with a maxillary transverse deficiency received ERME treatment, cone-beam computed tomography (CBCT) and lateral cephalometric radiographs were measured before and after treatment, and statistical differences in the measured items were evaluated with corresponding statistical methods to explore the skeletal and dental changes. RESULTS: After ERME treatment, there was a statistical increase in the maxillary basal bone arch width, nasal cavity width, maxillary alveolar bone arch width, and maxillary dental arch width. A buccal inclination of the maxillary alveolar bone and a buccal inclination and buccal movement in the alveolar bone of maxillary first molars were found. The maxillary skeletal expansion was statistically greater than the dental expansion. Increases in the mandibular alveolar bone arch width and dental arch width happened after treatment. A decrease in angle ANB and an increase in Ptm-A, U1-SN, U1-PP, L1-MP, and L6-MP were found after treatment. No statistical changes in the growth pattern-related measured items were observed. CONCLUSIONS: ERME could expand the maxillary basal bone arch width, nasal cavity width, maxillary alveolar bone arch width, and maxillary dental arch width. The maxillary skeletal expansion was greater than the dental expansion. Secondary increases in the mandibular alveolar bone and dental arch widths would happen after ERME. ERME would result in a mandibular advancement, a labial inclination of maxillary anterior teeth, and an increase of maxillary sagittal length, and would not change the patient's growth pattern. TRIAL REGISTRATION: This study was approved by the Institutional Review Board of the West China Hospital of Stomatology, Sichuan University. (WCHSIRB-D-2020-446).

Trueness of intraoral scanning of edentulous arches: A comparative clinical study.

PURPOSE: To compare the accuracy of intraoral scanning (IOS) of the edentulous arch with the hybrid protocol of cast digitization (CD), and to investigate the effect of arch type and area on trueness. MATERIALS AND METHODS: Participants that were edentulous in both arches were recruited. Two impression protocols were used; the IOS as the test protocol with an IOS device (TRIOS 4; 3Shape, Denmark), and the CD as the control, including tracing compound (TRACING STICKS; Kemdent, UK) for border molding, polyvinyl siloxane (Hydrorise Monophase; Zhermack, Italy) for impression, and cast digitization with a laboratory scanner (ceramill® map400, AMANNGIRRBACH, Germany). Scanned files were exported to a 3D inspection software (Geomagic Control X; 3D Systems, NC) for trueness analysis. The CD file (reference file) for each participant was split into 2 areas; the dynamic area representing the mobile tissues at the peripheral border, and the static area representing the rest of the arch. Statistical analyses were performed with 1-sample t-test for the difference between CD and IOS protocols, paired sample t-test for the difference between the static and dynamic areas for each arch, and an independent sample t-test for the difference between the maxillary and mandibular arches for each area, with α = 0.05. Effect size was calculated with Cohen's d (d), with 0.2 as small, 0.5 as medium, and 0.8 as large. RESULTS: A total of 21 participants were included. The difference between the IOS and CD protocol was significant for all subset comparisons (p < 0.001, d: 2.5-6.2, large effect size). Dynamic areas had lower trueness in comparison with static areas (p < 0.001, d = 4.57, large effect size for the maxillary arch, p < 0.001, d = 3.96, large effect size for the mandibular arch). Mandibular arch had lower trueness in comparison with the maxillary arch (p < 0.001, d = 1.45, large effect size for the static areas, p = 0.009, d = 0.85, large effect size for the dynamic areas, p < 0.001, d = 1.71, large effect size for all areas). Color difference map showed marked positive deviation in the buccal dynamic areas of both arches, and nonmatching areas with evident overstretching. CONCLUSIONS: While the IOS of edentulous arches could be feasible for attached mucosa, providing a functional shape for the peripheral border remains a challenge, with a thinner and more outward border for the IOS in comparison with the CD protocol. The IOS of the mandibular arch is more difficult and has lower trueness in comparison with the maxillary arch.

The Correlation between Mandibular Arch Shape and Vertical Skeletal Pattern.

Background and Objectives: The aim of this study was to evaluate the correlation between the mandibular arch shape and the vertical skeletal pattern in growing patients. Materials and Methods: A total of 73 Caucasian patients (33 males and 40 females; mean age 9.4) were retrospectively enrolled from a pool of patients treated in chronological order at the Department of Orthodontics, University of Foggia, Italy, from April 2018 to December 2021. Each patient received a laterolateral radiograph and a digital scan of the dental arch. Eight cephalometric parameters (lower gonial angle, intermaxillary angle, divergence angle, Wits index, Jarabak ratio, OP-MP angle, PP-OP angle, and ANB) and five dental measurements (posterior mandibular arch width, anterior mandibular arch width, mandibular occlusal angle, posterior width on distobuccal molar cusps, and molar angle) were analyzed and then compared. A Spearman's rho correlation test between the cephalometric measurements and the dental measurements was performed. Statistical significance was set at p < 0.05. Results: A negative statistically significant correlation was found between the Jarabak ratio and the intermolar angle; a statistically significant correlation was also observed between the Wits index, the posterior mandibular width, and the occlusal mandibular angle; the ANB angle and the occlusal mandibular angle; the intermaxillary angle (PP-PM) and the mandibular occlusal angle, posterior mandibular width on the disto-vestibular cusp, and the intermolar angle; and the OP-MP angle and mandibular occlusal angle and the posterior mandibular width on the disto-vestibular cusp. Conclusions: The mandibular arch form may be related to certain predisposing features in craniofacial morphology, such as jaw divergence, the Jarabak ratio, and the intermaxillary angle.

Accuracy of three digital scanning methods for complete-arch tooth preparation: An in vitro comparison.

STATEMENT OF PROBLEM: The accuracy of digital scanning for complete dental arch and implant-supported complete-arch restorations has been reported. However, research addressing the accuracy of digital scanning methods for complete-arch tooth preparation is lacking. PURPOSE: The purpose of this in vitro study was to compare the accuracy of intraoral scanning, impression scanning, and cast scanning for complete-arch preparation. MATERIAL AND METHODS: Maxillary and mandibular jaw typodonts with 28 teeth prepared for complete crowns were used as reference casts and digitized as reference data sets with a desktop scanner. Three digital scanning methods were applied. First, the reference casts were each scanned 10 times with an intraoral scanner to generate the intraoral scanning group data sets. Second, the reference casts were each captured 10 times by using polyvinyl siloxane impression material, and the impressions were scanned with a desktop scanner to generate the impression scanning group data sets. Third, the impressions obtained in the impression scanning group were used to make gypsum casts which were then digitized with a desktop scanner to generate the cast scanning group data sets. Accuracy was determined by trueness and precision. Three-dimensional deviations of the prepared arches and anterior and posterior segments were measured from root mean square values and depicted on color-difference maps. Differences among test groups were analyzed by using a 1-way ANOVA and the post hoc Bonferroni test for normally distributed data or the Kruskal-Wallis test with Bonferroni correction for non-normally distributed data (α=.05). RESULTS: The trueness of the maxillary arch was significantly higher in the impression scanning group than in the cast scanning and intraoral scanning groups (P<.05), but no significant differences were found among the 3 groups of the mandibular arch (P>.05). The precision of both arches was significantly higher in the impression scanning and intraoral scanning groups than in the cast scanning group (P<.05). Color maps showed horizontal symmetrical displacement in the intraoral scanning group relative to the reference data sets and within-group unilateral distal-end distortion. Irregular arch deformations were noted in the impression scanning group, and buccal and occlusal expansion occurred in the anterior-posterior direction in the cast scanning group. Pooled data for anterior teeth indicated that the trueness was lowest in the intraoral scanning group; however, that for the maxillary anterior teeth did not differ, while that for the mandibular anterior teeth differed significantly among groups (P<.05). For the posterior teeth, deviation was the lowest in the impression scanning group, and significant differences were noted in both arches among the 3 groups (P<.05). CONCLUSIONS: Of the methods tested, impression scanning was the most accurate for the creation of a digital cast of a complete prepared arch.

Impact of orthodontic brackets on intraoral and extraoral scans.

INTRODUCTION: The purpose of this study was to evaluate whether the presence of orthodontic brackets influences the accuracy of digital models generated by intraoral and extraoral scanning from the same patients. METHODS: Eighteen orthodontic patients in permanent dentition underwent full-arch intraoral scanning with a CEREC Omnicam scanner (Dentsply Sirona, York, Pa). Alginate impressions from each patient's arch were taken, and plaster models were made and scanned. Intermolar, intercanine, and mesiodistal width of the incisors were measured on 2 digital and 1 plaster models. Analysis of variance or Friedman's test was used, with differences between pairs verified by the Bonferroni test or Wilcoxon test, respectively. Both digital models were superimposed using surface-based registration. RESULTS: Lin's lowest coefficient of agreement was 0.960 (95% confidence interval, 0.900-0.984), which was clinically adequate. No statistically significant differences between the 3 types of model measurements were observed, except for the mandibular left lateral incisor in which scanned intraoral digital models presented Δmedium of 0.05 mm, which was higher than the plaster model. The superimposition of the extraoral and intraoral digital models revealed a minimum difference between models with a mean of means of 0.12 ± 0.03 mm. CONCLUSIONS: Brackets bonded to teeth affected intraoral scanning; however, the intraoral digital models are clinically comparable and present fewer distortions than plaster models. Moreover, measurements on intraoral and extraoral digital models are excellent in terms of trueness and precision and can be used clinically and in plaster models.

Accuracy of intraoral scan images in full arch with orthodontic brackets: a retrospective in vivo study.

OBJECTIVES: The purpose of this retrospective study was to evaluate the accuracy of intraoral scan (IOS) images in the maxillary and mandibular arches with orthodontic brackets. MATERIAL AND METHODS: From digital impressions of 140 patients who underwent orthodontic treatment, consecutive IOS images were selected based on standardized inclusion criteria: Two pre-orthodontic IOS images (IOS1 and IOS2) of permanent dentition with fully erupted second molars and IOS images obtained immediately after orthodontic bracket bonding (IOSb). Superimpositions were performed to evaluate the reproducibility of repeated IOS images. Accuracy of IOSb images was analyzed by comparing the average surface errors between IOS1c and IOS2c images, which were IOS images cut based on the same region of the interest as between IOS1 and IOSb images. RESULTS: A total of 84 IOS images was analyzed. The average surface errors between IOS1 and IOS2 images were 57 ± 8 µm and 59 ± 14 µm in the maxillary and mandibular arch, respectively, and their reliability was almost perfect. The average errors between IOSb and IOS1c images exhibited an increase, which measured 97 ± 28 µm in the maxillary arch and 95 ± 29 µm in the mandibular arch. These surface deviations between IOSb and IOS1c images were significantly larger in each region as well as entire dentition (P < 0.001) compared to those between IOS1c and IOS2c images. CONCLUSIONS: The average surface errors of the scans with brackets showed increased values compared with those without brackets. This suggests that orthodontic brackets could affect the trueness of intraoral scan images. CLINICAL RELEVANCE: It is necessary for clinicians to consider the effect of brackets on digital impression when using IOS images in orthodontic patients.

Arch Asymmetry in Patients With Cleft Lip and Palate After Rehabilitation Treatment Using Stereophotogrammetry.

ABSTRACT: Arch asymmetry in cleft patients is a current problem that interdisciplinary treatment aims to solve. This research proposed to analyze the final rehabilitation, according to the arch symmetry of these patients. Thirty-five patients aged between 18 and 30 years, rehabilitated with a fixed partial denture or implants in the cleft area. The analysis was performed using digitalized dental casts with a laser model scanner (R700TM; 3Shape A/S, Holmens Kanal 7, 1060, Copenhagen/Denmark), analyzed with a Vectra Analysis Module software program (VECTRA H1; Canfield Scientific, 4 Wood Hollow Road, Parsippany, NJ 07054). Three linear measurements were evaluated, incisal-canine, canine-molar, and incisal-molar distance. The Student t test was applied to test the significance (P = 0.05) of an observed sample by correlation coefficient test (r-value). Female patients showed a significant correlation in arch symmetry. According to the rehabilitation treatment, patients who received implants showed a high correlation and significant symmetry at all maxillary distances. Finally, according to the cleft side in the maxillary dimensions, even though the majority of patients had clefts on the left side, only patients with a cleft on the right side showed symmetry in this area. Patients rehabilitated with implants in the cleft area showed a more symmetrical maxillary arch than those restored with fixed partial dentures.

An Investigation of Three-Dimensional Maxillary Arch Morphometry of Children With Unilateral Cleft Lip and Palate.

ABSTRACT: The aim of this study was to evaluate the effects of multiple factors (congenital and postnatal treatment factors) on the treatment outcome by assessing the maxillary arch dimension of children with unilateral cleft lip and palate (UCLP). Eighty-five Pakistani children with UCLP were taken who received cheiloplasty and palatoplasty. Laser scanned 3D digital models of UCLP subjects were prepared before any orthodontic treatment and bone grafting at 7.69 ±â€Š2.46 (mean ±â€Šstandard deviation) years of age. Inter-canine width (ICW), inter-molar width (IMW), and arch depth (AD) measurements of maxillary arch were measured with Mimics software. Multiple linear regression analyses were used to evaluate the association between congenital factors (age, gender, UCLP side, family history of cleft) and postnatal treatment factors (techniques of cheiloplasty and techniques of palatoplasty) with maxillary arch dimensions (ICW, IMW, and AD). P value was set at 5%. The mean (standard deviation) dimensions of ICW, IMW, and AD are 26.7 (5.70) mm, 43.3 (4.66) mm, and 27.1 (5.26) mm, respectively. There is no significant association found between multiple factors and maxillary arch dimensions. This regression analysis shows no significant association between multiple factors and MAD in this sample.

Accuracy of complete-arch intraoral scans based on confocal microscopy versus optical triangulation: A comparative in vitro study.

STATEMENT OF PROBLEM: Fully digital dentistry is contingent on an accurate digital scan of the complete arch; however, the dimensional accuracy of different scanners for digitizing a complete arch is unclear. PURPOSE: The purpose of this in vitro study was to compare the accuracy of 2 intraoral scanners, TRIOS 3 (TR) and CEREC Omnicam (OC). Accuracy was assessed from changes to reference distances defined along the complete arch of a reference cast including 3 precision balls and 3 prepared teeth. The local accuracy (trueness and precision) of the scanned surface of each prepared tooth was also assessed. MATERIAL AND METHODS: Each intraoral scanner was used to scan a metal mandibular reference cast 20 times in a randomized sequence. The complete dental arch of a mandible in which the second left premolar was missing contained 2 prepared teeth, the first left premolar (LP) and the first left molar (LM) to accommodate a fixed partial denture (FPD) with complete crowns. The arch also contained an inlay preparation on the right second premolar (RP). Stainless-steel precision balls (ball centers P1, P2, and P3), which were welded onto the left second molar (P1), the incisal contact point of the central incisors (P3), and the right first molar (P2), were used to determine dimensional changes over the complete arch. Powder (CEREC Optispray) was applied to the reference cast to reduce reflections. Deviations between the reference cast (digitized with high precision before the tests) and the intraoral scans were calculated using Matlab R2015a and Geomagic Design X. To evaluate dimensional changes, the centers of the balls were determined, and their absolute changes in distance (ΔP1P2, ΔP1P3, and ΔP2P3) were calculated. To calculate accuracy (trueness and precision) in relation to the prepared teeth, the mesh deviation between the intraoral scans and the superimposed reference teeth was determined. The data were statistically analyzed by using a nonparametric rank-based 2-way repeated-measures ANOVA, and differences in least square means for pairwise comparisons were calculated (α=.05). RESULTS: The following mean absolute changes in distance were determined: ΔP1P2, TR: 74.4 µm, OC: 119.6 µm; ΔP1P3, TR: 24.7 µm, OC: 17.2 µm; ΔP2P3, TR: 68.6 µm, OC: 41.2 µm. The scanner did not have a statistically significant effect (P=.118) for distance, and the different distances differed significantly from each other (P<.001). Both scanners provided results acceptable for the fabrication of inlays and short-span FPDs. A complete-crown scan was more accurate than an inlay scan (P<.001). Accuracy and precision were better for TR than for OC (P<.001). CONCLUSIONS: With maximum discrepancies of 192.5 to 294.6 µm across the dental arch, complete-arch scans cannot yet be recommended for the fabrication of long-span FPDs.

Dental arch perimeter changes as a result from premature loss of primary anterior teeth due to trauma: A case series in infant and pre-school children.

BACKGROUND: The premature loss of primary anterior teeth in deciduous arches is a controversial topic in the literature, especially due to the lack of robust scientific evidence about the consequences in the arch perimeter space and magnitudes of the effects involved. AIM: Evaluate the association between premature loss of primary anterior teeth and dental arch perimeter changes, according to clinical variables as deciduous arch type, erupted primary canines, midline involvement and deleterious oral habits, on infants and pre-school children. DESIGN: Patients with avulsion or referral to extraction due to traumatic dental injuries (TDI) were evaluated. After the tooth loss, two trained operators measured the tooth/teeth space, both with a digital caliper and a dry tip compass. The clinical documentation included photographs and radiographs. Follow-up visits occurred from the baseline and every two months over a 12-month period. Chi-square test was used to evaluate the association between arch perimeter changes and clinical variables (α = 0.05). A descriptive statistic was performed to explore the magnitude of space changes, with 95% confidence intervals. RESULTS: Eighteen infants/children (mean, 2.78 ± 1.39 years) were included. Nine patients presented space loss (50.0%) (mean, -1.32 mm), six patients gained space (33.3%) (mean, +1.55 mm), and three patients presented space maintenance (16.7%). Clinical variables did not influence dental arch perimeter changes. CONCLUSIONS: Premature loss of primary anterior teeth, as well as deleterious oral habits, deciduous arch type, midline involvement and erupted primary canines, were not associated with dental arch perimeter changes.