Enhancing systematic reviews in orthodontics: a comparative examination of GPT-3.5 and GPT-4 for generating PICO-based queries with tailored prompts and configurations.

OBJECTIVES: The rapid advancement of Large Language Models (LLMs) has prompted an exploration of their efficacy in generating PICO-based (Patient, Intervention, Comparison, Outcome) queries, especially in the field of orthodontics. This study aimed to assess the usability of Large Language Models (LLMs), in aiding systematic review processes, with a specific focus on comparing the performance of ChatGPT 3.5 and ChatGPT 4 using a specialized prompt tailored for orthodontics. MATERIALS/METHODS: Five databases were perused to curate a sample of 77 systematic reviews and meta-analyses published between 2016 and 2021. Utilizing prompt engineering techniques, the LLMs were directed to formulate PICO questions, Boolean queries, and relevant keywords. The outputs were subsequently evaluated for accuracy and consistency by independent researchers using three-point and six-point Likert scales. Furthermore, the PICO records of 41 studies, which were compatible with the PROSPERO records, were compared with the responses provided by the models. RESULTS: ChatGPT 3.5 and 4 showcased a consistent ability to craft PICO-based queries. Statistically significant differences in accuracy were observed in specific categories, with GPT-4 often outperforming GPT-3.5. LIMITATIONS: The study's test set might not encapsulate the full range of LLM application scenarios. Emphasis on specific question types may also not reflect the complete capabilities of the models. CONCLUSIONS/IMPLICATIONS: Both ChatGPT 3.5 and 4 can be pivotal tools for generating PICO-driven queries in orthodontics when optimally configured. However, the precision required in medical research necessitates a judicious and critical evaluation of LLM-generated outputs, advocating for a circumspect integration into scientific investigations.

3D evaluation of cranial and dentofacial morphological differences between individuals with mouth breathing and nasal breathing.

INTRODUCTION: The present study aimed to identify the morphological differences in cranial and dentofacial structures between individuals with mouth-breathing and nasal-breathing. MATERIALS AND METHODS: The study included 120 individuals, 60 each in the nasal breathing (NB) and mouth breathing (MB) groups. 3D stereophotogrammetry, lateral cephalometric radiographs, and intraoral examination results were recorded by the researchers to determine the morphological differences between the MB group and the NB group. The study utilized cephalometric radiographs for 2D hard tissue measurements and 3D stereophotogrammetric records for linear and angular measurements. RESULTS: Statistically significant differences were found between the NB and MB groups' SNB angles (respectively, 79.3 ± 3.04, 76.6 ± 4.24, and p=0.002). Also, the NB group's SN-GoGn angle was lower than the MB group's (respectively, 31.5 ± 5.12, 36.0 ± 5.55, and p=0.002). Considering the Jarabak ratio, the NB group's Jarabak ratio was higher than the MB group (respectively,65.7 ± 4.16, 62.6 ± 4.10, and p=0.014). In 3D stereophotogrammetry measurements, increased Li-Me' was detected in the MB group than in NB group. CONCLUSION: Mouth breathing results in significant morphological differences that affect the development of both soft tissues and skeletal structures. Orthodontists utilize these characteristic features observed in mouth-breathing anomalies for early diagnosis and consider referring their patients for medical treatment of mouth breathing.

Clinical comparative study on the accuracy of palatal rugae in models obtained by different impression materials and intraoral scanning.

OBJECTIVE: Palatal rugae are frequently used in the evaluation of tooth movement after treatment in orthodontics and as a stable region in superimposition. It is important to note that the impression method and material used to record the rugae region affect the accuracy of the impression. The aim of this study is to compare the accuracy of palatal rugae, in three-dimensional (3D) by employing both conventional and digital impression methods. MATERIALS AND METHODS: In this study, 22 patients (12 females, 10 males) mean age of 13.5 ± 1.7 years old were selected with complete permanent dentition. Three different impressions were taken from the maxillae of the patients: conventional impression using silicone rubber impression material, conventional impression using alginate impression material, and optical impression using an intraoral scanner. The impressions' digital data were analyzed by the GOM Inspect (Version 2018, Braunschweig, Germany), a 3D analysis software. The Root Mean Square (RMS) values of the total ruga region were evaluated in this software. The data were statistically analyzed using the Jamovi program. The Kruskal-Wallis test and Mann-Whitney U test were performed due to the non-normal distribution of the data. RESULTS: There is no statistically significant difference between the comparison points of the right and left rugae's medial and lateral points and total rugae regions' RMS values. Although there was no statistically significant difference, the total RMS values of alginate and digital scan measurements showed closer results than the RMS values of silicone and digital scan measurements. CONCLUSION: The study found that there was no statistically significant difference in the total RMS values of the ruga region between traditional and digital impression methods. CLINICAL RELEVANCE: The treatment period in orthodontics is long. Different impression materials and methods can be used for diagnostic, mid-treatment, and final impressions. For superimpositions and treatment and post-treatment palatal ruga evaluations, traditional and digital impression methods are clinically acceptable and can be used as alternatives to each other.

A comparative analysis of AI-based chatbots: Assessing data quality in orthognathic surgery related patient information.

INTRODUCTION: The aim of the current study is to evaluate the quality, reliability, readability, and similarity of data provided by different AI-based chatbots in the field of orthognathic surgery. MATERIALS AND METHODS: Guidelines on orthognathic surgery were reviewed, and a list of questions for patients to ask chatbots was produced by two reasearchers. The questions were categorized into 'General Information and Procedure' and 'Results and Recovery', with 30 questions in each category. Five different scoring criteria were used to evaluate the chatbot responses to 60 questions: Ensuring Quality Information for Patients (EQIP) tool, Reliability Scoring System (adapted from DISCERN), Global Quality Scale (GQS), Simple Measure of Gobbledygook (SMOG) and Similarity Index. RESULTS: The highest mean values were observed in OpenEvidence for EQIP tool, SMOG, and Similarity Index, while for Reliability and GQS assessment criteria, MediSearch showed the highest values. When evaluated in terms of reliability and quality, all three AI-based chatbots demonstrated high reliability and good quality; however, they required at least a college-level education for readability based on the SMOG index. Additionally, upon assessment of similarity, ChatGPT-4 displayed high originality, while OpenEvidence exhibited a high degree of similarity. CONCLUSION: AI-based chatbots with a variety of features have usually provided answers with high quality, reliability, and difficult readability to questions. Although the medical information in the field of orthognathic surgery provided through chatbots is of higher quality, it is recommended that individuals consult their healthcare professionals on this issue.

The Quality of CLP-Related Information for Patients Provided by ChatGPT.

OBJECTIVE: To assess the quality, reliability, readability, and similarity of the data that a recently created NLP-based artificial intelligence model ChatGPT 4 provides to users in Cleft Lip and Palate (CLP)-related information. DESIGN: In the evaluation of the responses provided by the OpenAI ChatGPT to the CLP-related 50 questions, several tools were utilized, including the Ensuring Quality Information for Patients (EQIP) tool, Reliability Scoring System (Adapted from DISCERN), Flesh Reading Ease Formula (FRES) and Flesch-Kinkaid Reading Grade Level (FKRGL) formulas, Global Quality Scale (GQS), and Similarity Index with plagiarism-detection tool. Jamovi (The Jamovi Project, 2022, version 2.3; Sydney, Australia) software was used for all statistical analyses. RESULTS: Based on the reliability and GQS values, ChatGPT demonstrated high reliability and good quality attributable to CLP. Furthermore, according to the FRES results, ChatGPT's readability is difficult, and the similarity index values of this software exhibit an acceptable level of similarity ratio. There is no significant difference in EQIP, Reliability Score System, FRES, FKGRL, GQS, and Similarity Index values among the two categories. CONCLUSION: OpenAI ChatGPT provides a highly reliable, high-quality, but challenging to read, and acceptable similarity rate in providing information related to CLP. Ensuring that information obtained through these models is verified and assessed by a qualified medical expert is crucial.

Three-dimensional evaluation of social smile asymmetry in patients with unilateral impacted maxillary canine: a 3D stereophotogrammetry study.

OBJECTIVE: This study aimed to evaluate social smile asymmetry in patients with unilateral impacted maxillary canine on 3D stereophotogrammetric images. MATERIAL AND METHODS: The 3D social smile images of participants with unilateral impacted maxillary canine (n:20) and without impaction as a control group (n:20) were included. The images were recorded with a hand-held 3D stereophotogrammetry device (Fuel3D® Scanify®) and Geomagic Essentials 2 reverse engineering software were used for analyses. After the orientation process of the 3D records, the tissues around the smile area were divided into five morphological regions: cheek, upper lip lateral and medial, and lower lip lateral and medial. The deviation margins in the negative and positive directions for the 95% mesh rate and the total percentages of meshes between - 0.5- and + 0.5-mm deviations were calculated. ICC, paired samples t test, independent samples t test, and the Mann-Whitney U test were used for statistical analyses. RESULTS: In individuals with impacted canine, the amount of maximum positive deviation in the upper lip medial was 5.64 mm ± 1.46 and maximum negative deviation was - 4.6 mm ± 1.17. In the control group, mean of deviation limits for all parameters was less than 1.19 mm ± 2.62, while in individuals with unilateral impacted maxillary canine, the maximum value was 8.34 mm ± 2.23. The mesh percentage between - 0.5 and 0.5-mm deviations was over 95% in all morphological areas in the control group, while in the impacted canine group, the number of meshes within the specified deviation limits was less than 95%. CONCLUSION: Individuals with unilateral impacted maxillary canine exhibit greater asymmetry in social smile compared to the control group, with the asymmetry being most prominent near the corners of the mouth and cheeks. CLINICAL RELEVANCE: Amount of asymmetry was higher in impaction group compared to the control group in social smile. The quantification of a possible smile asymmetry due to the impacted canine is crucial for the diagnosis and treatment planning of orthodontic and/or orthognathic cases for ideal aesthetic results. Hence, smile asymmetry should not be overlooked and should be considered in diagnosis and treatment planning.

The effect of layer thickness on the accuracy of the different in-house clear aligner attachments.

OBJECTIVE: The accuracy of the attachments, one of the key components of clear aligner therapy, is important for obtaining more precise tooth movement. The aim of this study was to evaluate the accuracy of the ovoid, hemi-ellipsoid, and vertical rectangular attachments produced by the digital light-processing(DLP) 3-dimensional printing technologies with 25 µm, 75 µm, and 125 µm layer thickness. MATERIALS AND METHODS: The ovoid, hemi-ellipsoid, and vertical rectangular attachments were positioned onto the convex surface of the central incisor by the software. The printing process was carried out by a DLP printer using a commercially printed resin with 25 µm, 75 µm, and 125 µm layer thickness (n = 30, for each group). All test models' digital data was exported into the reverse engineering software for the superimposition. After selecting the 5 comparison points for the ovoid and vertical rectangular attachments, and 6 comparison points for the hemi-ellipsoid attachment, the Root Mean Square (RMS) was evaluated for each group. RESULTS: There is a statistically significant difference between the 25 µm and 125 µm layer thickness of total RMS values in the ovoid, hemi-ellipsoid, and vertical rectangular attachment groups (p = 0.001, p = 0.03, and p = 0.00 respectively). The printing time with the 25 µm layer thickness was 4 times longer than with the 125 µm layer thickness. CONCLUSIONS: This study revealed that the accuracy of the attachments used for in-house clear aligner therapy is affected by the layer thickness of the 3D printer. CLINICAL RELEVANCE: The layer thickness of the 3D printer is a crucial factor in determining attachment accuracy, but its clinical significance is minimal. Clinicians should make informed decisions about the appropriate layer thickness, taking into account their workflow preferences, time constraints, and other practical considerations specific to their clinical practice.

The effect of aging on the mechanical properties of 3-dimensional printed biocompatible resin materials used in dental applications: An in vitro study.

INTRODUCTION: The mechanical properties of biocompatible printable resin materials in an intraoral environment is still being investigated. This study aimed to assess the effect of the aging process on the mechanical properties of resin samples produced by stereolithography appearance (SLA) and digital light processing (DLP) 3-dimensional printer systems. METHODS: The cylindrical sample (4.00 × 20.00 mm) was designed by software, and the data were transformed into digital format. A DLP printer (n = 40) and an SLA printer (n = 40) carried out the printing process. The aging procedure was applied to 20 samples from each group using a thermocycling device. After the aging procedure, the samples were placed in the universal testing device for the 3-point bending test. RESULTS: This study showed that the aging procedure decreased maximum load, bending stress, and Young's modulus values and increased maximum deflection values of the DLP group (P <0.01). However, no statistical difference was detected in the parameters compared with the SLA group except for the maximum deflection values. Furthermore, statistically significant differences were found between maximum deflection and Young's module values of SLA and DLP control and study groups (P <0.05). CONCLUSIONS: This in vitro study revealed that the biocompatible printable resin materials produced by DLP and SLA printers had the mechanical strength to resist the values resembling the physiological occlusal forces even after the aging procedure and could produce intraoral appliances.

Comparing the physical and mechanical properties of different biocompatible three-dimensional resin materials in possible use of dental appliances: An in vitro study.

OBJECTIVE: This study aimed to assess the colour stability, water sorption, microhardness and water contact angle of two different 3D printing systems (SLA and DLP) in a possible use of producing paediatric and orthodontic dental appliances. MATERIALS AND METHODS: SLA and DLP printer systems produced a total of 160 disk samples with a diameter of 15.00 mm and a height of 2.00 mm. Colour changes of 64 samples were assessed in distilled water, coffee, coke and cherry juice and Vicker's microhardness tests were also conducted. Solubility and water sorption were held following the water contact angle assessment. Statistical analyses were performed using the SPSS software. Mann-Whitney-U test, Friedman test and Bonferroni post hoc Multiple Comparison Test were performed. RESULTS: In DLP and SLA groups, coffee had a statistically significant colouring effect regarding the assessment periods (P = .001, 20.09 ± 2.96, 22.09 ± 3.51, respectively), and the discolouration effect of coffee was higher in the SLA group at all endpoints (P < .05). At the same time, DLP was more affected by coke solution in T0-T1 and T0-T7 (P < .05). The values of water sorption showed statistically significant differences in the group of DLP compared to the SLA (P = .01, 121.11 ± 10.54, 92.78 ± 8.70, respectively). No statistical significance was detected between the solubility values and water contact angle of SLA and DLP groups. The SLA printer's microhardness values revealed statistically significantly higher values than the DLP group (P = .001) and a decrease was detected following the immersion period in the microhardness values of the SLA group (P = .022). CONCLUSION: The compared groups exposed to staining solutions revealed colour changes above the clinically acceptable values at all periods (ΔE00 = 2.25).

Evaluation of the accuracy of fully automatic cephalometric analysis software with artificial intelligence algorithm.

OBJECTIVE: The aim of this study is to evaluate whether fully automatic cephalometric analysis software with artificial intelligence algorithms is as accurate as non-automated cephalometric analysis software for clinical diagnosis and research. MATERIALS AND METHODS: This is a retrospective archive study using lateral cephalometric radiographs taken from individuals aged 12-20 years. Cephalometric measurement data were obtained from these lateral cephalometric radiographs by manual landmark marking with non-automated computer software (Dolphin 11.8). Again, the same radiographs were made using fully automatic digital cephalometric analysis software OrthoDx™ (AI-Powered Orthodontic Imaging System, Phimentum) and WebCeph (Assemblecircle, Seoul, Korea) with artificial intelligence algorithm, without manual intervention of the researcher and fully automatic markings and measurements were made by the software. RESULTS: According to the consistency test, a statistically significant good level of consistency was found between Dolphin and OrthoDx™ measurements and Dolphin and WebCeph measurements in angular measurements (ICC > 0.75, P < .01, ICC > 0.75, P < 0, respectively. 01). A weak level of consistency was found in linear measurement and soft tissue parameters in both software (ICC < 0.50, P < .05, ICC < 0.50, P < .05), and the difference between measurements was statistically found to be different from "0." CONCLUSION: The results obtained from fully automatic cephalometric analysis software with artificial intelligence algorithms are similar to the results of non-automated cephalometric analysis software, although there are differences in some parameters. To minimize the margin of error in artificial intelligence-based fully automatic cephalometric software, the manual intervention of the observer is needed.

Is YouTubeTM an adequate source of oral hygiene education for orthodontic patients?

INTRODUCTION: The present study aims to assess the quality, reliability and content of the information provided by the YouTubeTM videos on oral hygiene during orthodontic treatment, to reveal the efficacy of the videos for patients and to help dentists who use this platform as a source to guide their patients accurately. METHOD: In the beginning, it was found that the most common search term on oral hygiene during orthodontic treatment in Google Trends was 'how to clean braces'. A total of 150 videos containing keywords were reviewed, and 56 videos were assessed within the scope of the study. Videos were analysed for reliability score, content analysis and GQS criteria. RESULTS: According to the results, the mean video length was statistically significantly greater in rich-content videos than in poor-content videos (p = 0.024). In addition, the reliability score of rich-content videos was statistically significantly higher than that of poor-content videos (p = 0.026). Likewise, the GQS of rich-content videos was statistically significantly higher than that of poor-content videos (p < 0.001). However, the number of views, the number of likes, the number of dislikes, the number of comments, the number of days since upload, the interaction index and the view rate did not statistically significantly differ by content categories (p > 0.05). CONCLUSION: The present study concluded that the YouTubeTM videos providing oral hygiene education for patients receiving or scheduled for orthodontic treatment had poor content and overall medium quality. The instantaneous data collection was one of the study's limitations.

Evaluation of an automated approach for facial midline detection and asymmetry assessment: A preliminary study.

OBJECTIVE: To examine the level of agreement between the conventional method and a machine-learning approach to facial midline determination and asymmetry assessment. SETTINGS AND SAMPLE POPULATION: The study included a total of 90 samples (53 females; 37 males) with different levels of mandibular asymmetry. MATERIALS AND METHODS: Two researchers placed predefined soft tissue landmarks individually on selected facial frontal photographs and created 10 reference lines. The midsagittal line was determined as perpendicular to the midpoint of the bipupillary line, and the same two reference lines and facial landmarks were automatically determined by the software using machine-learning algorithms, and researchers created the other 8 reference lines using the facial landmarks that were determined automatically by the software. In the following stage, 2 linear and 10 angular measurements were made by a single researcher on 270 photographs, and the consistency and differences between the measurements were evaluated with a one-sample t test, an intraclass correlation coefficient (ICC) and Bland-Altman Plots. RESULTS: The level of agreement of measurements between the researchers and the software was low for eight parameters (ICC˂0.70). The one-sample t test revealed that differences between the software and researcher measurements of lip canting and pronasale deviation were not statistically significantly different (P > .05). Aside from the body inclination difference in Group 3 (samples with a mandibular body inclination difference >6°), there was no clinically significant difference (˂3°) between the measurements of the two methods. CONCLUSIONS: Machine-learning algorithms have the potential for clinical use in asymmetry assessment and midline determination and can help clinicians in a manual approach.

Displacement and stress distribution of Kilroy spring and nickel-titanium closed-coil spring during traction of palatally impacted canine: A 3-dimensional finite element analysis.

OBJECTIVE: To compare the stress distribution and initial displacements during traction of palatally impacted canine between Kilroy and nickel-titanium (NiTi) closed-coil springs by means of the finite element analysis. SETTING AND SAMPLE POPULATION: A finite element method analysis of two traction methods for a maxillary impacted canine. MATERIALS AND METHODS: The corresponding periodontal ligaments (PDLs), brackets, molar tubes and a 0.019 × 0.025-in base stainless-steel (SS) wire were modelled and imported to ANSYS SpaceClaim version 2020 R1. Traction was simulated under two different set-ups with equal force magnitude (60 g); (1) the Kilroy spring, which is made of 0.016-inch SS, and (2) the NiTi closed -coil spring. Von Mises stress distributions and initial displacements of the maxillary teeth were analysed. RESULTS: In both mechanics, while the highest stress was seen on the impacted canine (Kilroy, 10.41 kPa; NiTi closed-coil, 5.27 kPa), the stress distribution decreased as the distance from the impacted canine increased. The Kilroy spring showed a greater total displacement (465.60 µm) on the impacted canine. The higher stresses on the adjacent lateral (5.29 kPa) and premolar (6.41 kPa) occurred with the Kilroy spring. CONCLUSIONS: The Kilroy spring yielded higher stresses than the NiTi closed-coil spring on the impacted canine and the adjacent teeth. The difference between distribution of the stresses over the impacted canine induced greater displacement with the Kilroy spring, particularly in the vertical direction.

Effect of facial profile convexity on the perception of mandibular asymmetry using three-dimensional stereophotogrammetric images.

OBJECTIVE: The aim of this study was to test the hypothesis that sagittal anomalies have an effect on the perception of mandibular asymmetry. Secondly, it aimed to determine the asymmetry perception threshold of orthodontist and laypeople. SETTING AND SAMPLE POPULATION: A total of 90 individuals were included in the study from different professions (Orthodontist: n:45, layperson: n:45). MATERIALS & METHODS: The reference image was obtained with 3dMD device and selected from among the individuals with class I soft tissue relationship. In the sagittal direction, the chin area has been moved as to produce 5 and 10 degrees of change in facial convexity angle. Similarly, 0, 2, 4, 6, 8 and 10 mm changes were made and recorded in video format. Manipulated images were scored by participants with VAS method. RESULTS: When differences between the groups were evaluated, the reference image was scored similarly by orthodontists and layperson (P: .017). No statistically significant difference was observed between the groups in other parameters (P > .05). Asymmetry in 0-2 mm range was evaluated by orthodontist and layperson and statistically insignificant (P > .05). Similarly, the change between 8 mm and 10 mm was different in both groups and statistically insignificant (P > .05). Also, when there was no asymmetry, the sagittal direction was differently scored by the participants in both groups and statistically insignificant (P > .05). CONCLUSIONS: It was observed that the effect of sagittal direction changes on asymmetry perception was not statistically significant.

Dental crown symmetry in unilateral cleft lip and palate patients: A three-dimensional analysis on digital dental models.

OBJECTIVES: The purpose of this study was to conduct a 3-dimensional assessment of possible dental crown asymmetry in dental crown shape and/or size that was not clinically visible in unilateral cleft lip and palate (UCLP) patients on the maxilla and mandible and make a comparison to the control group without CLP. SETTING AND SAMPLE POPULATION: The maxillary and mandibular digital models of orthodontically treated 35 individuals with non-syndromic UCLP (mean age: 14.6 ± 2.1 years) and 35 class I individuals without CLP (mean age 14.1 ± 1.5 years). MATERIALS AND METHODS: The crowns of the anterior and posterior teeth were segmented and the teeth on the cleft side were mirrored in UCLP patients considering the arbitrary midsagittal plane as reference. The first alignment was landmark-based and it was followed by the best-fit method. After aligning the images, millimetric differences (deviation analysis) between aligned surfaces were analysed. Independent Samples t test and Mann-Whitney U test were used for statistical comparisons. RESULTS: The highest difference between the cleft side and non-cleft side in the UCLP group was observed in the central incisors (1.85 ± 0.79 mm). The mean difference between the groups in the central incisors was 1.20 mm (95% CI: -1.70; -0.69; P < 0.001). The mean of median values was found to be highest in the central incisors in the UCLP group as 0.72 ± 0.27 mm. It was 0.15 ± 0.05 mm in the control group. CONCLUSION: The difference between the cleft and non-cleft side may exceed 1 mm in the maxillary central incisors of unilateral CLP patients.

Hard- and soft-tissue symmetry comparison in patients with Class III malocclusion.

OBJECTIVE: Our aim was to describe hard- and soft-tissue asymmetry in people who have a skeletal Class III malocclusion, and to compare with those without asymmetry. We also performed a regional analysis of a possible correlation between facial soft- and hard-tissue asymmetries. METHODS: This retrospective study was performed with the use of the computed tomographic scans of 60 subjects. The skeletal Class III subjects were categorized into 2 subgroups: soft-tissue menton deviation ≤4 mm (n = 20) versus >4 mm (n = 20). The Class III groups were compared with a Class I symmetry group (n = 20). Hard and soft tissues were segmented into different morphologic areas and deviation calculated. Pearson correlation coefficients were obtained, and 1-way analysis of variance was conducted for statistical analysis. RESULTS: The highest deviation in the hard tissues of the Class III asymmetry group was in the corpus region (5.55 ± 3.05 mm), with the second highest in the angulus region (4.70 ± 2.43 mm). The highest average deviation in the soft tissues was seen in the lower cheek (7.04 ± 3.46 mm). In the different study groups, the amounts of asymmetry measured in anatomic structures on the mandible were found to be highly correlated between neighboring structures. CONCLUSIONS: Clinically and statistically significant differences were found in the anatomic regions located in the middle and lower thirds of the face. There was a medium or high correlation between condyle, coronoid process, ramus, and angulus regions. A low level of correlation was observed between middle face and mandibular asymmetries in hard-tissue upper cheek and lower cheek regions were correlated with different mandibular regions.

Three-dimensional evaluation of morphologic tooth symmetry in various malocclusions.

INTRODUCTION: The aim of this study was to evaluate the morphologic symmetry of the maxillary and mandibular teeth between the left and right quadrants in 3 dimensions using advanced engineering software. METHODS: The total sample comprised 120 dental casts of 60 patients with dental and skeletal Class I, Class II, and Class III malocclusions. They were divided into 3 groups of 40 dental casts (20 maxillary, 20 mandibular) belonging to 20 patients. The dental casts were digitized with an intraoral 3-dimensional scanner (TRIOS; 3Shape, Copenhagen, Denmark). Segmentation and superimposition procedures were carried out using Rapidform software (Inus Technology, Seoul, Korea). Teeth in the left and right quadrants (except for the second molars) in both jaws were superimposed using 3-point registration followed by surface-based registration; 3-Matic software (Materialise, Leuven, Belgium) was used for deviation analysis. RESULTS: The maximum mean deviations observed in the positive and negative directions were 0.14 ± 0.10 mm in the maxilla (for the Class I group) and 0.16 ± 0.09 mm for the Class III group. The differences of the maximum deviation amounts among the malocclusion groups were 0.47 ± 0.08 mm in negative direction in the maxillary teeth and 0.79 ± 0.17 mm in the mandibular arch. CONCLUSIONS: In the 3 malocclusion groups investigated, morphologic deviations were low and clinically insignificant. Symmetry of tooth morphology did not differ among Class I, Class II, and Class III malocclusions.

Three-dimensional analysis of tooth movements after palatal miniscrew-supported molar distalization.

INTRODUCTION: The aim of this prospective clinical study was to evaluate the dentoalveolar effects of a palatal miniscrew-supported molar distalization appliance using a 3-dimensional reverse engineering method. METHODS: This study sample comprised 21 patients at an average age of 13.6 years with a bilateral Class II molar relationship. Distalization was performed using skeletal anchorage. Dental casts were obtained just before treatment and after appliance removal, and they were scanned with a 3-dimensional dental scanner. The digital dental cast images were aligned. Four points and 2 lines were determined on each tooth, and the correlations between tooth movements and the linear and angular changes were analyzed 3 dimensionally. RESULTS: In the sagittal direction, the first molars showed a mean linear movement of 4.10 ± 1.57 mm, with distal tipping of 11.02°; the central incisors showed a mean distal movement of 0.95 ± 0.40 mm, with retroclination of 1.59 ± 0.59°. In the vertical direction, only the first molars showed intrusion, with a mean value of -0.59 ± 0.50 mm. Rotation of the first molars was 4.92° ± 3.09°. The second molars had the greatest rotation. The highest correlation among tooth movements was found between the first and second molars. CONCLUSIONS: Through support from the anterior palatal region, the maxillary first molars were distalized without anchorage loss. Furthermore, movement was observed in all 3 planes of space with reduction from the posterior to the anterior in the maxillary arch.