Quality in orthodontics: The role of customized appliances.

Orthodontics as well as dentistry are undergoing a technological revolution with advances in medical imaging, 3D printing and customization of appliances and devices. Digital orthodontics can be defined as the process of manufacturing customized appliances based on a target setup which incorporates tooth positioning in six-degrees-of-freedom. Three-dimensional medical imaging provides better diagnostic tools and allows for fabrication of orthodontic appliances based on the coordinates system of the occlusal plane within the facial anatomy. This article describes the state-of-the-art in goal-driven orthodontic treatment, warns against the commercialization of our profession, and highlights the advantages of lingual orthodontics in terms of protection of the enamel.

Incorrect measurements and misleading conclusions in the article "Comparison of the efficacy of tooth alignment among lingual and labial brackets: an in vitro study".

BACKGROUND/OBJECTIVE: To reproduce the methods and results of the study by Alobeid et al. (2018) in which the efficacy of tooth alignment using conventional labial and lingual orthodontic bracket systems was assessed. MATERIALS/METHODS: We used the identical experimental protocol and tested (i) regular twin bracket (GAC-Twin [Dentsply]) and lingual twin bracket systems (Incognito [3M]), (ii) together with NiTi 0.014" wires (RMO), and (iii) a simulated malocclusion with a displaced maxillary central incisor in the x-axis (2 mm gingivally) and in the z-axis (2 mm labially). RESULTS: The method described by Alobeid et al. (2018) is not reproducible, and cannot be used to assess the efficacy of tooth alignment in labial or lingual orthodontic treatment. Major flaws concern the anteroposterior return of the Thermaloy-NiTi wire ligated with stainless steel ligatures. The reproduced experimental setting showed that a deflected Thermaloy-NiTi wire DOES NOT move back at all to its initial stage (= 0 per cent correction) because of friction and binding (see supplemented video), neither with the tested labial nor with the lingual brackets. Furthermore, an overcorrection of up to 138 per cent, which the authors indicate for some labial bracket-wire combinations and which deserves the characterization "irreal", stresses the inappropriateness of the method of measurement.Further flaws include: a) incorrect interpretation of the measurement results, where a tooth tripping around (overcorrection) is interpreted as a better outcome than a perfect 100 per cent correction; b) using a statistical test in an inappropriate and misleading way; c) uncritical copying of text passages from older publications to describe the method, which do not correspond to this experimental protocol and lead to calculation errors; d) wrong citations; e)differences in table and bar graph values of the same variable; f) using a lingual mushroom shaped 0.013" Thermaloy-NiTi wire which does not exist; g) drawing uncritical conclusions of so called "clinical relevance" from a very limited in vitro testing. CONCLUSIONS: Clinical recommendations based on in vitro measurements using the Orthodontic Measurement and Simulation System (OMSS) should be read with caution.

Evaluating the treatment effectiveness and efficiency of Carriere Distalizer: a cephalometric and study model comparison of Class II appliances.

BACKGROUND: The purpose of this study was to evaluate the treatment effectiveness of Carriere Distalizer in comparison to Class II intermaxillary elastics and Forsus. METHODS: Three groups of patients treated with Class II intermaxillary elastics (n = 18), Carriere Distalizer (n = 18), and Forsus appliance (n = 18) were collected from three private orthodontic practices. Inclusion criteria were as follows: (1) 10-14 years old of start age with permanent dentition, (2) no history of previous orthodontic treatment, (3) complete pre- and post-treatment records, (4) dental Class II division 1 (end-to-end or more), (5) no pre-treatment transverse discrepancy, (6) non-extraction treatment plan, and (7) Class I post-treatment occlusal relationship. The data consisted of cephalometric and study model measurements from pre- and post-treatment records and treatment time. Two-tail Student t test was used to analyze the differences in cephalometric changes and dental corrections between Carriere Distalizer group and Class II elastics/Forsus group. RESULTS: All three groups of patients showed no differences in the age of treatment initiation, pre-treatment cephalometric measurements and discrepancy index (DI). The time of Class II correction for Carriere Distalizer was significantly shorter than that for Class II elastics; there was no difference in the length of Class II correction between Carriere Distalizer and Forsus groups. The amount of Class II correction (canine/molar relationship) was significantly lower for Carriere Distalizer when compared with Forsus appliance. Carriere Distalizer, similarly to Class II elastics, did not induce any statistically significant correction in skeletal component (ANB and Wits appraisal). CONCLUSIONS: There is no clinically significant skeletal correction induced by Carriere Distalizer in growing patients. Carriere Distalizer can be applied to treatment of mild to moderate Class II dental malocclusion over 6 months on average, although the total treatment time may be prolonged due to various side effects. Overall, the Carriere Distalizer appears to be no more effective or efficient than alternatives in the treatment of Class II malocclusion.

Memotain: A CAD/CAM nickel-titanium lingual retainer.

Approximately 1/2 of maxillary and 1/5 of mandibular multi-stranded lingual retainers fail during retention in some form, either bond failure or wire breakage. Memotain is a new CAD/CAM fabricated lingual retainer wire made of custom-cut nickel-titanium, as an alternative to multi-stranded lingual retainers. It offers numerous perceived advantages to the traditional multi-stranded stainless steel wire, including precision fit, avoidance of interferences, corrosion resistance and even the potential for minor tooth movement as an active lingual retainer.

A contemporary review of white spot lesions in orthodontics.

UNLABELLED: White spot lesions (WSL) associated with fixed orthodontic appliances are a common adverse effect of orthodontic treatment and represent a significant challenge to achieving esthetic excellence. The purpose of this article is to review the current evidence regarding diagnosis, risk assessment, prevention, intratreatment management, and postorthodontic treatment of WSL, and to provide clinical recommendations useful for both the orthodontist and the general dentist. Caries risk assessment should be incorporated into initial evaluations of orthodontic patients, and risk-specific prevention and management protocols can help to eliminate or minimize this clinical problem. There are multiple options for treatment of WSL, ranging from conservative to invasive techniques; the severity of lesions is a determinant of which option is most appropriate. CLINICAL SIGNIFICANCE: White spot lesions associated with orthodontic treatment are a common problem that can be minimized with appropriate prevention, management, and treatment approaches.

A novel biomechanical model assessing continuous orthodontic archwire activation.

INTRODUCTION: The biomechanics of a continuous archwire inserted into multiple orthodontic brackets is poorly understood. The purpose of this research was to apply the birth-death technique to simulate the insertion of an orthodontic wire and the consequent transfer of forces to the dentition in an anatomically accurate model. METHODS: A digital model containing the maxillary dentition, periodontal ligament, and surrounding bone was constructed from computerized tomography data. Virtual brackets were placed on 4 teeth (central and lateral incisors, canine, and first premolar), and a steel archwire (0.019 × 0.025 in) with a 0.5-mm step bend to intrude the lateral incisor was virtually inserted into the bracket slots. Forces applied to the dentition and surrounding structures were simulated by using the birth-death technique. RESULTS: The goal of simulating a complete bracket-wire system on accurate anatomy including multiple teeth was achieved. Orthodontic forces delivered by the wire-bracket interaction were 19.1 N on the central incisor, 21.9 N on the lateral incisor, and 19.9 N on the canine. Loading the model with equivalent point forces showed a different stress distribution in the periodontal ligament. CONCLUSIONS: The birth-death technique proved to be a useful biomechanical simulation method for placement of a continuous archwire in orthodontic brackets. The ability to view the stress distribution with proper anatomy and appliances advances our understanding of orthodontic biomechanics.

Imaging software accuracy for 3-dimensional analysis of the upper airway.

INTRODUCTION: The aim of this study was to compare the precision and accuracy of 6 imaging software programs for measuring upper airway volumes in cone-beam computed tomography data. METHODS: The sample consisted of 33 growing patients and an oropharynx acrylic phantom, scanned with an i-CAT scanner (Imaging Sciences International, Hatfield, Pa). The known oropharynx acrylic phantom volume was used as the gold standard. Semi-automatic segmentations with interactive and fixed threshold protocols of the patients' oropharynx and oropharynx acrylic phantom were performed by using Mimics (Materialise, Leuven, Belgium), ITK-Snap (www.itksnap.org), OsiriX (Pixmeo, Geneva, Switzerland), Dolphin3D (Dolphin Imaging & Management Solutions, Chatsworth, Calif), InVivo Dental (Anatomage, San Jose, Calif), and Ondemand3D (CyberMed, Seoul, Korea) software programs. The intraclass correlation coefficient was used for the reliability tests. A repeated measurements analysis of variance (ANOVA) test and post-hoc tests (Bonferroni) were used to compare the software programs. RESULTS: The reliability was high for all programs. With the interactive threshold protocol, the oropharynx acrylic phantom segmentations with Mimics, Dolphin3D, OsiriX, and ITK-Snap showed less than 2% errors in volumes compared with the gold standard. Ondemand3D and InVivo Dental had more than 5% errors compared with the gold standard. With the fixed threshold protocol, the volume errors were similar (-11.1% to -11.7%) among the programs. In the oropharynx segmentation with the interactive protocol, ITK-Snap, Mimics, OsiriX, and Dolphin3D were statistically significantly different (P <0.05) from InVivo Dental. No statistical difference (P >0.05) was found between InVivo Dental and OnDemand3D. CONCLUSIONS: All 6 imaging software programs were reliable but had errors in the volume segmentations of the oropharynx. Mimics, Dolphin3D, ITK-Snap, and OsiriX were similar and more accurate than InVivo Dental and Ondemand3D for upper airway assessment.

Accuracy in tooth positioning with a fully customized lingual orthodontic appliance.

INTRODUCTION: To understand orthodontic tooth movement, a method of quantification of tooth position discrepancies in 3 dimensions is needed. Brackets and wires now can be fabricated by CAD/CAM technology on a setup made at the beginning of treatment, so that treatment should produce a reasonably precise duplicate of the setup. The extent of discrepancies between the planned and actual tooth movements can be quantified by registration of the setup and final models. The goal of this study was to evaluate the accuracy of a CAD/CAM lingual orthodontic technique. METHODS: Dental casts of 94 consecutive patients from 1 practice, representing a broad range of orthodontic problems, were scanned to create digital models, and then the setup and final models for each patient were registered individually for the maxillary and mandibular dental arches. Individual tooth discrepancies between the setup and actual outcome were computed and expressed in terms of a six-degrees-of-freedom rectangular coordinate system. RESULTS: Discrepancies in position and rotation between the setup and outcome were small for all teeth (generally less than 1 mm and 4°) except for the second molars, where some larger discrepancies were observed. Faciolingual expansion in the posterior teeth was greater in the setup than in the final models, especially at the second molars. Linear mixed models showed that age, type of tooth, jaw, initial crowding, time in slot-filling wire, use of elastics, days in treatment, interproximal reduction, and rebonding, were all influences on the final differences, but, for most of these factors, the influence was small, explaining only a small amount of the discrepancy between the planned and the actual outcomes. CONCLUSION: These fully customized lingual orthodontic appliances were accurate in achieving the goals planned at the initial setup, except for the full amount of planned expansion and the inclination at the second molars. This methodology is the first step toward understanding and measuring tooth movement in 3 dimensions.

Clinical application of 3D imaging for assessment of treatment outcomes.

This paper outlines the clinical application of CBCT for assessment of treatment outcomes, and discusses current work to superimpose digital dental models and 3D photographs. Superimposition of CBCTs on stable structures of reference now allow assessment of 3D dental, skeletal and soft tissue changes for both growing and non-growing patients. Additionally, we describe clinical findings from CBCT superimpositions in assessment of surgery and skeletal anchorage treatment.

REGISTRATION OF ORTHODONTIC DIGITAL MODELS.

Current methods to assess outcomes and change in orthodontics are comparison of photographs, cephalometric measurements and superimpositions, and comparisons/measurements on dental casts. Digital models are a relatively new records modality in orthodontics. They offer numerous advantages in terms of storage space, spatial registration and superimposition. The purpose of this chapter is to determine the reproducibility of: 1) establishing occlusion of independently scanned digital models; and 2) registering digital models obtained after treatment on their homologous digital model setups produced before treatment. Reliability of both procedures was assessed with two random samples of five patient's models. In both experiments, three replicate positionings of the models per patient were created and variability in position was evaluated by the maximum surface difference between replicates, and the standard deviation of the surface distances between replicates respectively. Based on the data obtained, we concluded that it is reliable to register independently scanned models to a scanned surface of the models in occlusion. Surface-to-surface registration of final orthodontic digital models to planned setup models also is reproducible.

Accuracy and landmark error calculation using cone-beam computed tomography-generated cephalograms.

OBJECTIVE: To evaluate systematic differences in landmark position between cone-beam computed tomography (CBCT)-generated cephalograms and conventional digital cephalograms and to estimate how much variability should be taken into account when both modalities are used within the same longitudinal study. MATERIALS AND METHODS: Landmarks on homologous cone-beam computed tomographic-generated cephalograms and conventional digital cephalograms of 46 patients were digitized, registered, and compared via the Hotelling T(2) test. RESULTS: There were no systematic differences between modalities in the position of most landmarks. Three landmarks showed statistically significant differences but did not reach clinical significance. A method for error calculation while combining both modalities in the same individual is presented. CONCLUSION: In a longitudinal follow-up for assessment of treatment outcomes and growth of one individual, the error due to the combination of the two modalities might be larger than previously estimated.

Pharyngeal airway volume and shape from cone-beam computed tomography: relationship to facial morphology.

INTRODUCTION: The aim of this study was to assess the differences in airway shape and volume among subjects with various facial patterns. METHODS: Cone-beam computed tomography records of 62 nongrowing patients were used to evaluate the pharyngeal airway volume (superior and inferior compartments) and shape. This was done by using 3-dimensional virtual surface models to calculate airway volumes instead of estimates based on linear measurements. Subgroups of the sample were determined by anteroposterior jaw relationships and vertical proportions. RESULTS: There was a statistically significant relationship between the volume of the inferior component of the airway and the anteroposterior jaw relationship (P = 0.02), and between airway volume and both size of the face and sex (P = 0.02, P = 0.01). No differences in airway volumes related to vertical facial proportions were found. Skeletal Class II patients often had forward inclination of the airway (P <0.001), whereas skeletal Class III patients had a more vertically oriented airway (P = 0.002). CONCLUSIONS: Airway volume and shape vary among patients with different anteroposterior jaw relationships; airway shape but not volume differs with various vertical jaw relationships. The methods developed in this study make it possible to determine the relationship of 3-dimensional pharyngeal airway surface models to facial morphology, while controlling for variability in facial size.

Working with DICOM craniofacial images.

The increasing use of cone-beam computed tomography (CBCT) requires changes in our diagnosis and treatment planning methods as well as additional training. The standard for digital computed tomography images is called digital imaging and communications in medicine (DICOM). In this article we discuss the following concepts: visualization of CBCT images in orthodontics, measurement in CBCT images, creation of 2-dimensional radiographs from DICOM files, segmentation engines and multimodal images, registration and superimposition of 3-dimensional (3D) images, special applications for quantitative analysis, and 3D surgical prediction. CBCT manufacturers and software companies are continually working to improve their products to help clinicians diagnose and plan treatment using 3D craniofacial images.