Experimental Investigation of the Biomechanical Properties of a Newly Introduced Self-ligating Bracket

Orthodontic tooth movement is the result of a combination of biological and biomechanical phenomena, which occur under the application of specific forces by means of orthodontic appliances. Both the behavior of elastic materials and the mechanical factors, that control and influence the effectiveness of the applied forces, must be thoroughly considered in the design of an optimal orthodontic system. In addition, self-ligating brackets have gained lately a broad acceptation in the scientific society and have been extensively investigated. Nevertheless, in these days of multifaceted versatile brackets, the available evidence concerning the potential forces applied to the teeth by the various combinations of self-ligating mechanisms and archwires is limited. Under the perspective of the biomechanical principles applied to the orthodontic mechanotheraphy, an in-vitro study was designed and carried out, presenting mainly the following objectives: (a) comparative investigation of the forces generated during the initial stages of complex orthodontic tooth malalignment correction with various bracket-archwire combinations, by means of an experimental biomechanical set-up, (b) assessment of torque effectiveness in the sagittal plane during later stages of a simulated orthodontic tooth movement by utilizing diverse bracket designs combined with a variety of rectangular archwires. In terms of this experimental investigation have been used a newly introduced 0.016 inch twin slot bracket (Swiss Nonligating Bracket/ SNB), as well as 3 different kinds of 0.018 inch slot brackets (Speed, Mini mono, Brilliant). A variety of archwire combinations has been used in order to evaluate the amount of the correction of a complex malalignment and the torque efficiency of the above mentioned bracket systems. These archwires are differentiated basically according to both their material and cross-section dimensions. The Orthodontic Measurement and Simulation System (OMSS) allowed us in each measurement cycle simultaneously a three-dimensional registration of the force and moment systems, which affected the left mandibular incisor during the performance of a mock orthodontic tooth movement. Analyzing the obtained results on the whole, it is obvious that the various ligation types applied in each bracket system exert a significant influence on the degree of the malalignment’s correction. Specifically, the degree of correction concerning the self-ligating brackets ranges from 72 % - 98 %, respectively, whereas the same measurements for the conventional brackets demonstrate values of 51.7 % - 77.39 %. The constricting alignment capabilities by the conventional brackets can be attributed to the frictional forces generated between bracket and archwire. In the current study the values referring to the mean maximal forces in the inciso-gingival axis by using the 0.007" NiTi and the 0.009" NiTi combined with all bracket designs did not overcome 0.88 N. However, the relevant values by utilizing the 0.0135" NiTi archwires, as well as those with wider cross-sections, were significantly higher and reached magnitudes up to 6.55 N. The moments generated in this in vitro investigation approach principally the limits set from the previous investigations, including though some restrictions. In particular, all the evaluated moments exert greater magnitude than 10 N with an exception of the SNB combined with 0.016 x 0.016" BioTorque archwire, where the values are only 4.9 Nmm and cannot display sufficient clinical efficiency. On the contrary, SPEED brackets demonstrate enhanced torque capabilities by expressing torsional movement of 17 Nmm by application of a 0.016" x 0,016" stainless steel archwire and have reached the value of 35.2 Nmm by ligation of a 0.016" x 0.022" stainless steel archwire. The superiority of the self-ligating brackets against the conventional ones is suggested through this study, as far as the exertion of light and constant forces is concerned. Moreover, the active self-ligating brackets have demonstrated slightly better results as the passive ones. The qualities of the NiTi spring play a prominent role in the demonstration of these advantageous biomechanical properties. Additionally, it should be underlined that the greater impact factor on the expression of better torque capabilities is imposed by the archwire dimension, rather than its material properties

Development and BiomechanicalInvestigation of a New Compound Palatal Arch

Abstract. : Background and Aim: : There are many advantages in using a transpalatal arch in orthodontic treatment. In addition to the active movement of individual teeth, such an arch can be used to provide additional anchorage. The aim of this study was to further develop and improve both the clinical and the biomechanical properties of the conventional transpalatal arch. Material and Methods: : Currently available compound material components form an established part of orthodontic therapy. The Compound palatal arch® broadens the scope of this treatment system. The biomechanical effects of the newly developed Compound palatal arch® were verified by comparing them with those of commercially available conventional transpalatal arches. The recently developed Compound palatal arch® is made of one compound element: nickel-titanium/stainless steel. The specific dimensions and design of the nickel-titanium element are aimed at exploiting its superelasticity, even during active molar movement. The biomechanical investigation was carried out using sixcomponent measuring sensors to register the forces and moments in the three spatial dimensions (x, y and z) at 37 °C. The following appliances were investigated: Goshgarian transpalatal arch, quad-helix appliance, Arndt memory expander®, and Compound palatal arch®. Results: : Transpalatal arches could not be inserted without the arch being under tension. This is particularly important when the arch is being used for anchorage purposes. The Goshgarian arch had to be classified as problematic for the movement of single teeth as the load/deflection rate was high. However, this can be utilized for anchorage purposes. The clinical advantage of a quad-helix appliance is the option for asymmetric tooth movement. Conclusions: : This study showed that the quad-helix was effective for both unilateral and bilateral derotation as well as for transversal tooth movement. However, expansions should be confined to ≤ 4 mm, and derotations to < 10°, as forces and moments are otherwise not within the physiologic range. The Arndt memory expander® displayed no advantages over either the quad-helix appliance or the Goshgarian transpalatal arch. Nor did it display any superelastic properties. The linear relationship, the relatively high forces and moments, and the lack of clinical adjustability cast doubts on the benefits of this appliance. The newly developed Compound palatal arch® showed substantial advantages in molar derotation compared with conventional transpalatal arches. Superelastic properties were achieved through the design and positioning of the nickel-titanium element. Expansion with the Compound palatal arch® was comparable with that with conventional transpalatal arches. The clinical advantage is in the fact that this appliance can be reactivated and that dental asymmetries can be treate

Comparative Analysis of Sliding Resistance of Different Lingual Systems

Objective:&nbsp;To analyse and compare the frictional properties of 4 lingual systems combined with two types of stainless steel archwire (0.016x0.022, 0.018x0.025) and a 0.018x0.025 TMA archwire by simulating different misalignment situations in vitro.&nbsp;Material and Methods:&nbsp;Five randomly chosen brackets from each system (e-Brace, Harmony, Incognito, and STb) were used for the measurements and to simulate an upper first premolar extraction case. The friction tests were performed using a material testing machine in combination with a specialized test rig.&nbsp;Results:&nbsp;The lowest absolute friction values were found with the 0.016x0.022 SS wire in a passive configuration. STb provided the lowest mean friction, while Harmony brackets displayed the highest friction. The TMA Beta Titanium wire showed the highest friction values, but maintained proportions similar to those of the other wires as tip and torsion increased.&nbsp;Conclusion:&nbsp;The type of bracket has a significant impact on friction, and there is a positive correlation between mesiodistal bracket width and resistance to sliding. The archwire sections and materials and the vertical displacement, also significantly affect the friction generated by the system

Learning about tooth removal with robot technology

Deze PhD-thesis richt zich op een fundamenteel onderzoek van de extractieleer en maakt daarbij gebruik van robottechnologie. Het onderzoek omvat zes inhoudelijke hoofdstukken, waarin verschillende aspecten van dit onderwerp worden behandeld. Het tweede hoofdstuk analyseert de literatuur over robottechnologie in de tandheelkunde en wijst op de matige kwaliteit van beschikbare literatuur, zeker als het op klinische toepassingen aankomt. Hoofdstuk 3 biedt een overzicht van robotsystemen in alle deelgebieden van de tandheelkunde sinds 1985. Hoofdstuk 4 introduceert een meetopstelling om krachten en bewegingen bij tandextracties nauwkeurig vast te leggen, terwijl hoofdstuk 5 de resultaten van een serie experimenten voor wat betreft krachten en momenten weergeeft. Hoofdstuk 6 beschrijft het bewegingsbereik en de snelheden tijdens tandheelkundige extracties, zoals gemeten met een robotarm. Hoofdstuk 7 beschrijft de ontwikkeling en eigenschappen van een classificatiemodel voor extracties op basis van kracht- en bewegingsgegevens. De conclusie benadrukt de toenemende interesse in robotinitiatieven in de tandheelkunde, de behoefte aan wetenschappelijke validatie van de toegevoegde waarde daarvan en het potentieel van robottechnologie om ons fundamentele begrip van de extractieleer te vergroten. De studies benadrukken het belang van gegevensverzameling, analyse en samenwerking tussen verschillende disciplines om ons fundamentele begrip van extracties te verbeteren, met een focus op tandheelkundig onderwijs en uiteindelijk de patiëntenzorg

Comparative Analysis of Sliding Resistance of Different Lingual Systems

Objective: To analyse and compare the frictional properties of 4 lingual systems combined with two types of stainless steel archwire (0.016x0.022, 0.018x0.025) and a 0.018x0.025 TMA archwire by simulating different misalignment situations in vitro. Material and Methods: Five randomly chosen brackets from each system (e-Brace, Harmony, Incognito, and STb) were used for the measurements and to simulate an upper first premolar extraction case. The friction tests were performed using a material testing machine in combination with a specialized test rig. Results: The lowest absolute friction values were found with the 0.016x0.022 SS wire in a passive configuration. STb provided the lowest mean friction, while Harmony brackets displayed the highest friction. The TMA Beta Titanium wire showed the highest friction values, but maintained proportions similar to those of the other wires as tip and torsion increased. Conclusion: The type of bracket has a significant impact on friction, and there is a positive correlation between mesiodistal bracket width and resistance to sliding. The archwire sections and materials and the vertical displacement, also significantly affect the friction generated by the system

Evaluation of the results of orthodontic treatment by non-rigid image registration and deformation-based morphometry

The goal of this research was to find out, whether the non-rigid registration of dental casts can be used in the evaluation of orthodontic treatment and to develop a program, which would at least partially automatize the evaluation process of images. The aim was also to experiment the evaluation of three-dimensional models of the casts. This research was delimited to cover only the evaluation of malocclusions within the dental arch. The relationships between the dental arches were not considered. This thesis was done in the University of Vaasa at the Department of Electrical Engineering and Energy Technology as a part of the HammasSkanneri research project, whose aim is to automatize the digitization and archiving of dental casts. This research used two-dimensional images of dental casts which were taken of orthodontically treated patients before and after orthodontic treatment. Non-rigid registration was performed by using a registration tool of Fiji software. The evaluation of the accuracy of the registration was performed by measuring distances between manually inserted landmarks, and by comparing the linear and angular parameters of the registered images and the original target images. The displacements of the teeth were approximated with the help of deformation-based morphometry. The accuracy of registration is within reasonable error limits, if the image is taken straight from above of the cast and the registration is performed with the help of landmarks inserted by a human. Estimation of the changes showed that the movement of teeth can be coarsely measured by using deformation-based morphometry based on change estimates that resemble the Jacobian estimates. A set of programs, which partially automatize the evaluation of the accuracy and the changes, were developed. Three-dimensional imaging of the casts was unsuccessful, and thus the development of 3D evaluation system was left as a future research topic.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format

Remote digital monitoring during the retention phase of orthodontic treatment: A prospective feasibility study

Objective: To evaluate if a remote digital monitoring system added at the end of orthodontic treatment could positively influence the retention phase by reducing the occurrence of misfit of removable appliances, number of emergency appointments (EA), and orthodontic relapse. Methods: Twenty-seven patients who completed active orthodontic treatment were divided into the study and control groups. In addition to the standard chairside follow-up appointments at month 1 (T1), month 3 (T2), month 6 (T3), the study group patients were monitored using Dental Monitoring® with monthly intra-oral scans. Occurrence of misfit of removable retainers, number of EAs, and intercanine width change were recorded for both groups. Differences in EAs and retainer fit were assessed using the chi-square test. Intra-group and inter-group differences in the intercanine width were assessed with Friedman test and Mann–Whitney U test, respectively (α = 0.05). Results: The study group showed a significantly lower occurrence of misfit of removable retainers (p = 0.027) compared to the control group. No significant inter-and intra-group difference was found in the EAs and intercanine width change at each time-point. Conclusions: Integrating remote monitoring systems, such as Dental Monitoring®, to the retention phase of the orthodontic treatment may lower the occurrence of misfit of removable retainers. However, a small sample size and a short observation period limit the strength of this evidence. These preliminary results tentatively suggest that remote monitoring technologies may be beneficial, especially during the COVID-19 pandemic, when the regularity of in-office visits might be disrupted

Evaluation of Transverse, Bodily Tooth Movement and Its Effects on the Surrounding Hard Tissue

Orthodontic expansion has been associated with uncontrolled tipping and alveolar bone loss. Recent research evaluating orthodontic expansion has shown osteoblastic activity on the buccal cortical bone apical to the dehiscence. We hypothesize that the negative effects seen during orthodontic expansion is a result of tipping rather than expansion. The aim of the present study was to produce buccal translation, with little or no coronal tipping, and evaluate hard tissue changes of the dental-alveolar complex. A prospective, randomized, split-mouth study was conducted with 11 patients (average age 14.1 years, range 12.5-16.9 years) requiring maxillary first premolar extractions for comprehensive orthodontic treatment. Pre and post-treatment records included models, photographs, and small field of view cone beam computed tomographic images (FOV CBCT) of the right and left maxillae. One maxillary first premolar was randomly chosen and moved to the buccal with 50 grams of force applied approximately at the tooth’s center of resistance. The other premolar served as the control tooth. Forces were re-activated every 3 weeks for approximately 9 weeks of active movement, after which the tooth was held in place for 3 weeks to allow for maturation of the surrounding tissue. Pre and post treatment records were analyzed and superimposed to evaluate changes in the dental-alveolar complex. The results showed significant movement (0.96 mm, p=0.008) of the experimental premolar occurred 3 mm apical to the CEJ. There was minimal buccal tipping (2.2°, p=0.003). Maximum and minimum buccal bone heights decreased 0.60 mm (p=0.003) and 0.25 mm (p=0.262) respectively. The distribution of the maximum bone height measurement was bimodal, with 6 patients showing 0.42 mm (IQR -0.25 mm to 0.52mm) and 5 patients showing 8.3 mm (IQR 7.15 to 10.05) of vertical bone loss. Buccal bone thickness at the midline 3 mm apical to the CEJ decreased 0.63 mm (p=0.016). Based on direct measurements and CBCT superimpositions, buccal bone grew 0.46 mm (p=0.005) and 0.51 mm (p=0.036), respectively. Using light continuous forces, it is possible to produce buccal tooth movement with only limited amounts of tipping. With such movements buccal bone growth occurs, but there are potential limitations