Predictability of orthodontic tooth movement with aligners: effect of treatment design.

BACKGROUNDS: The present study was designed to define: (1) which are the less predictable OTM with Invisalign aligners when the treatment plan is designed by expert operators, (2) if the presence and shape of attachments influence the predictability of OTM and (3) if patients' demographics influence OTM predictability. The sample comprises 79 prospectively recruited patients (mean age 30.8 years; SD 12.0; 23 M, 56 F), treated by expert operators with an average of 27 aligners (SD 15) in the maxillary arch and 25 aligners (SD 11) in the mandibular arch. Post-treatment digital models and final virtual treatment plan models were exported from ClinCheck® software as STL files and subsequently imported into Geomagic Qualify ®software, to compare final teeth positions. The differences were calculated and tested for statistical significance for each tooth in the mesial-distal, vestibular-lingual and occlusal-gingival directions, as well as for angulation, inclination and rotation. In addition, the statistical significance of categorical variables was tested. RESULTS: The lack of correction was significant for all movements and in all group of teeth (P < 0.01) except for the rotation of maxillary first molar. The prescribed OTM, the group of teeth and movement, the frequency of aligner change and the use of attachment influence the outcome. The greatest discrepancies in predicted and achieved tooth position were found for angular movements and rotation of teeth characterized by round-shaped crowns, for a ratio of approximately 0.4° per 1° prescribed. Optimized attachments for upper canines and lower premolar rotation seem not working properly. Second molar movements are mostly unexpressed. Furthermore, changing the aligner every 14 days will reduce the lack of correction of the 12% with respect to 7 days aligner change. CONCLUSIONS: Predictability of orthodontic movement with aligners still has limitations related to the biomechanics of the system: the shape of some attachments and the characteristics of aligner material need to be redefined. However, the results of this study allow to properly design the virtual treatment plan, revealing how much overcorrection is needed and which attachments are most effective.

Scanning electron microscopy analysis of aligner fitting on anchorage attachments.

PURPOSE: The aims of the study were (1) to evaluate the fitting of three different aligners (Invisalign [Align Technology, Santa Clara, CA, USA], CA Clear Aligner [Scheu-Dental, Iserlohn, Germany] and F22 [Sweden&Martina, Due Carrare, Italy]) on anchorage attachments using scanning electron microscopy (SEM), and (2) to analyze the influence of 2 different types of resin used to build attachments on aligner fitting. METHODS: Using STL files of a patient, six resin casts were obtained and rectangular attachments were bonded on them. Conventional bulk-fill resin was used to build upper attachments while a flowable resin was used to build the lower ones. Passive aligners were adapted on each cast and then sectioned buccolingually. Microphotographs of the obtained sections were performed using a SEM and then micrometric measurements of aligner fitting on anchorage attachments were recorded. RESULTS: Analyzing the overall fitting of upper arch aligners, Invisalign provided a significantly better fitting with respect to F22 (P = 0.009); differences were not significant when comparing Invisalign with CA Clear Aligner, and CA Clear Aligner with F22. Analyzing the overall fitting of lower arch aligners, F22 provided a significantly better fitting with respect to CA Clear Aligner (P = 0.008) and Invisalign (P = 0.011). The analysis showed a significantly better fitting on upper attachments, built using conventional bulk-fill resin (P = 0.034). CONCLUSIONS: Invisalign, CA Clear Aligner and F22 have comparable performance in terms of fitting on anchorage attachments. Conventional bulk-fill resin provides the best fitting on anchorage attachments.

Scanning electron microscopy evaluation of aligner fit on teeth.

OBJECTIVES: The fitting of aligners on anchorage teeth is a crucial factor in clear aligner orthodontics. The purpose of this experimental study was to evaluate the fitting of two aligner systems, Invisalign and CA-Clear Aligner, using scanning electron microscopy (SEM). MATERIALS AND METHODS: Passive aligners (Invisalign and CA-Clear Aligner) were adapted on resin casts obtained by stereolithography (STL) files of a patient, and then sectioned buccolingually. Upper and lower central incisors, upper and lower first premolars, and upper and lower first molars were the regions analyzed. Representative microphotographs of sections were taken with a scanning electron microscope (SEM); a total of 160 micrometric measurements were obtained and analyzed with ANOVA tests. RESULTS: Invisalign provided an overall better fit on lower incisors ( F = 11.48, P = .0095) and on lower molars ( F = 19.93, P = .0012). Considering the different regions, Invisalign provided better fit at the gingival edge of the buccal aspect on lower incisors ( F = 11.33, P = 0.0056) and at the gingival edge of the lingual aspect on upper premolars ( F =5.34, P = 0.0047). On the upper molars, Invisalign provided better fit at the gingival edge of the buccal aspect, while CA-Clear Aligner provided better fit at the buccal maximum convexity, on the buccal cusp, on the occlusal groove and at the palatal cusp. On lower molars, Invisalign showed a more accurate fit at the buccal aspect points. CONCLUSIONS: Invisalign and CA-Clear Aligner exhibited comparable fit on anchorage teeth. Invisalign provided better fit at the gingival edges of aligners, while the CA-Clear Aligner provided better fit on complex occlusal surfaces.

Buccolingual Inclination Control of Upper Central Incisors of Aligners: A Comparison with Conventional and Self-Ligating Brackets.

OBJECTIVE: The upper incisors torque expression is essential for the orthodontic treatment accuracy. Various orthodontic devices are claimed to have different inclination control capacity. The purpose of this retrospective study was to compare the radiographic buccolingual inclination of upper incisors in patients treated with three different orthodontic techniques. MATERIAL AND METHODS: Conventional brackets (Victory, 3M), self-ligating appliances (Damon Q, Ormco), and aligners (Invisalign, Align Technology) were tested. Cephalometric data of 25 patients with similar skeletal and dental pretreatment parameters were collected for each technique. Position changes of upper central incisors were assessed with radiographic evaluation before and after therapy. Three different parameters were considered: 11∧SnaSnp, 11∧Ocl and I+ TVL. All variables were measured before (T0) and after (T1) treatment and their variation over treatment was assessed. RESULTS: When evaluating angular measurements, 11∧SnaSnp and 11∧Ocl angles showed the highest numeric variation with conventional brackets. Lowest values were reported with aligners. However, the differences among various techniques were not significant for both angles (P>0.05). Also I+ TVL linear value variation did not show significant differences among the different groups tested (P>0.05). CONCLUSION: Conventional multibrackets appliance showed the highest incisal position variations over treatment, but the differences among various groups were not significantly different.

Root resorption during orthodontic treatment with Invisalign®: a radiometric study.

BACKGROUND: Root resorption (RR) is described as a permanent loss of tooth structure from the root apex. Many reports in the literature indicate that orthodontically treated patients are more likely to have severe apical root shortening, interesting mostly maxillary, followed by mandibular incisors. The aim of the study was to investigate the incidence and severity of RR in adult patients treated with aligners. The study group consisted of 71 class I adult healthy patients (mean age 32.8 ± 12.7) treated with aligners (Invisalign®, Align Technologies, Santa Clara, CA, USA). All incisors, canines, upper first premolars, and first molars were assessed. Root and crown lengths of 1083 teeth were measured in panoramic radiographs at the beginning (T0) and at the end (T1) of clear aligner therapy. Individual root-crown ratio (RCR) of each tooth and therefore the relative changes of RCR (rRCR) were determined. A decrease of rRCR was assessed as a reduction of the root length during treatment. RESULTS: All patients had a minimum of one teeth affected with a reduction of root length, on average 6.38 ± 2.28 teeth per patient. Forty one, 81% of the 1083, measured teeth presented a reduction of the pre-treatment root length. A reduction in percentage of >0% up to 10% was found in 25.94% (n = 281), a distinct reduction of >10% up to 20% in 12.18% (n = 132) of the sample. 3.69% (n = 40) of the teeth were affected with a considerable reduction (>20%). CONCLUSIONS: Orthodontic treatment with Invisalign® aligners could lead to RR. However, its incidence resulted to be very similar to that described for orthodontic light forces, with an average percentage of RR < 10% of the original root length.

Use of clear aligners in open bite cases: an unexpected treatment option.

In open bite case treatments, a proper diagnostic differentiation is essential in determining the appropriate corrective procedures. Dental open bites are generally more responsive to treatment with orthodontics alone, whereas skeletal open bites often require a combination of orthodontics and orthognathic surgery. Patient selection and treatment principles for non-surgical open bite treatment routinely include fixed appliances both labial or lingual. However, removable clear aligners have gained a consistent popularity in the treatment of complex cases including open bite malocclusions. In this article, the authors describe three different clinical cases in which open bite cases had been satisfactorily treated by using clear aligners.

Maxillary molar distalization with aligners in adult patients: a multicenter retrospective study.

BACKGROUND: The aim of the present study was to test the hypothesis that bodily maxillary molar distalization was not achievable in aligner orthodontics. METHODS: Forty lateral cephalograms obtained from 20 non-growing subjects (9 male, 11 female; average age 29.73 years) (group S), who underwent bilateral distalization of their maxillary dentition with Invisalign aligners (Align Technology, Inc., San José, CA, USA), were considered for the study. Skeletal class I or class II malocclusion and a bilateral end-to-end class II molar relationship were the main inclusion criteria. Cephalograms were taken at two time points: (T0) pretreatment and (T2) post-treatment. Treatment changes were evaluated between the time points using 39 variables by means of paired t test. The level of significance was set at P < 0.05. Reproducibility of measurements was assessed by the intraclass correlation coefficient (ICC). RESULTS: The mean treatment time was 24.3 ± 4.2 months. At the post-treatment point, the first molar moved distally 2.25 mm without significant tipping (P = 0.27) and vertical movements (P = 0.43). The second molar distalization was 2.52 mm without significant tipping (P = 0.056) and vertical movements (P = 0.25). No significant movements were detected on the lower arch. SN^GoGn and SPP^GoGn angles showed no significant differences between pre- and post-treatment cephalograms (P = 0.22 and P = 0.85, respectively). CONCLUSIONS: Aligner therapy in association with composite attachments and class II elastics can distalize maxillary first molars by 2.25 mm without significant tipping and vertical movements of the crown. No changes to the facial height were revealed.

Lower incisor extraction treatment with the Invisalign® technique: three case reports.

The extraction of a lower incisor can lead to satisfactory orthodontic results for patients with moderate to severe lower incisor crowding. Invisalign(®) is a treatment modality for such treatments, moving teeth with precision and reducing inconvenience for the patient. Three case reports are presented in this article supporting the above statements.

Orthodontics in the Mediterranean Area.

The article describes on the results of the first Workshop that SIDO organized in December 2005 in Cairo getting together twenty Countries who discussed Orthodontics in the Mediterranean Area. The aim was to take a picture, for the first time, of the state of Orthodontics in the different Mediterranean Countries using it as basis for a further co-operation. Progress in Orthodontics (published in English, indexed in Medline, free of charge website and downloading) was offered by SIDO as the means for a scientific and organizational sharing, and to spread a Mediterranean Orthodontic culture all over the world. The first step toward mutual understanding was completed and for the first time we collected data and the Mediterranean Orthodontic Integration Project (MOIP), on which we can base a coming meeting and debate, was introduced.

Computer-aided interactive indirect bonding.

INTRODUCTION: The introduction of the virtual occlusal set-up, limited to the permanent dentition with dento-dental and dento-alveolar discrepancies, based on the straight wire technique with final arches .020" x .025" ss in straight wire brackets .022" x .028" is an evolution of the 3D digital model with clinical impact. AIM: To present a computer-aided solution to orthodontic indirect bonding, allowing accurate positioning of straight-wire brackets based on a virtual occlusal set-up resulting from the treatment plan. MATERIAL AND METHODS: Computer-aided indirect bonding was applied in two cases: a Class II patient in the permanent dentition, crowding, rotation of upper and lower bicuspids and a Class I patient in the permanent dentition with already extracted 1.4, 2.4, 3.4, 4.4, severe crowding, rotation, arch form reduction. Speed brackets were utilized in both cases. RESULTS: In the first case the brackets' starting position on the patient corresponds to the final position on the virtual occlusal set-up. In the second case the resulting occlusion at the end of treatment corresponds to the final occlusion on the virtual occlusal set-up. DISCUSSION: The computerized tools employed in the process enabled precise bracket placement on the stone model. An algorithm from the virtual set-up is the determinant for the precision. CONCLUSION: Computer aided indirect bonding is a method of placing brackets precisely.

Effect of different light sources and guides on shear bond strength of brackets bonded with 2 adhesive systems.

INTRODUCTION: This study assessed the effect of different light sources and light guides on the shear bond strength and failure site of orthodontic brackets bonded with 2 adhesive systems (Quick Cure [Reliance Orthodontic Products, Itasca, Ill] and Transbond XT [3M/Unitek, Monrovia, Calif]). METHODS: Ninety bovine permanent mandibular incisors were randomly divided into 6 groups according to the adhesive system and light-curing procedure used. Each group consisted of 15 specimens; 90 stainless steel brackets were bonded to the teeth. Each adhesive system was light-cured with a halogen light (Ortholux XT, 3M/Unitek) for 20 seconds and the conventional light guide as controls. The remaining groups were cured with a halogen light (Ortho 2000 [Reliance Orthodontic Products, Itasca, Ill]) and a Power Slot light guide (Reliance Orthodontic Products) for 6 and 10 seconds. After bonding, all samples were stored in distilled water for 24 hours and then tested in a shear mode on a universal testing machine. RESULTS: No significant differences in terms of bond strength values were found among the 6 groups, but significant differences in debond locations were found among the 6 groups tested. CONCLUSIONS: Power Slot light guides can be recommended as advantageous alternatives for fast-curing composite resins during orthodontic bonding.

Digital treatment objectives: procedure and clinical application.

OBJECTIVES: the introduction of digital study models in the orthodontic practice changed the traditional stone gipsotec to a virtual gipsotec and the orthodontist has the possibility to see, immediately on the computer, this basic analysis with a great reduction of space and time. The aim of this study is to extend the use of digital models to the occlusal virtual set-up in 3D and have the orthodontist simulate and visualize the resulting occlusion from a suggested treatment plan for the malocclusion. METHODS AND MATERIALS: a case is presented where the treatment plan involvers extractions. The malocclusion is a Class II division 1 in the permanent dentition where an extraction treatment of 1.4, 2.4, 3.5 et 4.5 is planned: the final result shows the new occlusal relationship with proper anchorage management of the extraction spaces. From the primary silicon impression, a digital model is obtained followed by the virtual set up according the prescription of the treatment plan. More digital treatment objectives can be performed for the same malocclusion from the primary digital models, according to different treatment plans and the resulting occlusion visualized. RESULTS: the basic principle for the virtual occlusal set-up is the straight-wire system with the final position of the teeth resulting both from the bracket prescription and the final rectangular wire in a full slot engagement. CONCLUSIONS: the resulting dental arches show a correct arch form, arch coordination and a proper dental intercuspation. The results coming from different virtual simulations are analyzed; all these simulations need only one pair of impressions. Limits of this virtual method are that it can be used only in full permanent dentition and for cases of dento-alveolar or dento-dental discrepancy.

Distalization of maxillary molars using the speed system: a clinical and radiological evaluation.

AIM: To show how a self-ligating system can provide bodily movement of maxillary molars without extraoral devices or lingual appliances, reducing the need for patient compliance. The control of these tooth movements has been clinically and radiologically substantiated. METHODS: The biomechanical principles, patient selection, and steps of the treatment are described. Some reference points are shown on the lateral cephalogram for superimposition, to evaluate the sagittal, vertical, and angular changes. RESULTS: A number of cases have been treated with this technique, both distalization of maxillary first and second molars, with bodily movement and satisfactory anchorage management. CONCLUSION: The described system works efficiently, all with only intraoral appliances, but the use of light and continuous forces to reach bodily distal movement without secondary effects is mandatory. The described system also produces the desired objectives with a short treatment time.

Control of tooth movements with the Speed system.

Steps taken to evolve the straight-wire system eventually led to the development of self-ligating brackets. The Speed system, comprehensive of bracket, wires, force, and anchorage management, is a significant evolutionary development. The design property of the fourth wall in the Speed bracket allows the Ni-Ti wire to be placed in the slot fully. Closure of the gate activates the wire for the desired type and direction of tooth movement. A sequence of round, square, rectangular wires, Ni-Ti and stainless steel, permits a complete control of the tooth position during the different phases of the orthodontic treatment. In this study, the effectiveness of the system is investigated in four groups of patients: Class II, div 1 with four first bicuspid extractions; Class II, div 2 non-extraction; Class II div 1 non-extraction in mixed dentition; Skeletal Class III skeletal treated with an orthodontic-surgical treatment plan. Treatment results were assessed using the intra-oral photographs, and radiographs taken at the start of treatment, at the end of active treatment, and in retention. Satisfactory control of tooth positions during the horizontal, mesio-distal and torque movements, both in the extraction and non-extraction cases were observed. During the course of treatment, in extraction cases where sliding mechanics are used, shifting of the anchorage from posterior to the anterior unit is possible as a result of increased forces. This shift is facilitated by the activation of the spring clip on the anterior teeth. The advantages of the self-ligating Speed system are the low levels of force used, low friction, and precise control of tooth movements.