Scanning electron microscopy evaluation of aligner fit on teeth

Mantovani, Edoardo; Castroflorio, Enrico; Rossini, Gabriele; Garino, Francesco; Cugliari, Giovanni; Deregibus, Andrea; Castroflorio, Tommaso

doi:10.2319/120417-827.1

Cited by 29 publications

(31 citation statements)

References 19 publications

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“…Therefore, we set out to investigate both the gap and aligner thickness in six aligner systems, performing both 2D and 3D measurements. Data were obtained using nano-CT, an investigative method that does not cause even microscopic alterations in the sample, and should therefore provide more accurate data than cutting machine and SEM analysis [21,22].…”

Section: Discussionmentioning

confidence: 99%

“…the gap between the inner surface of aligners and the external surface of the tooth. The fit is determined by the thermoforming process (pressure and temperature), the elastic modulus of the materials used [21], the presence of divots or attachments [22] and the hygroscopic expansion that occurs in contact with saliva [23].…”

Section: Introductionmentioning

confidence: 99%

“…The only studies focusing on the topic have been carried out using a scanning electron microscope (SEM) to obtain microphotography of buccolingual sections of passive aligners, created by a cutting machine and fitted to stereolithographic models [21,22]. The first of these studies concluded that both Invisalign (Align Technology, San Jose, CA, USA) and CA-Clear Aligner (Scheu-Dental, Iserlohn, Germany) systems provided good fit.…”

Section: Introductionmentioning

confidence: 99%

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MicroCT X-ray comparison of aligner gap and thickness of six brands of aligners: an in-vitro study

et al. 2020

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Background: To investigate and compare the gap (i.e. fit) and thickness of six aligner systems (Airnivol, ALL IN, Arc Angel, F22, Invisalign and Nuvola) using industrial computed tomography (CT). The null hypothesis was that there would be no detectable differences in either measurement between the aligners investigated. Materials and methods: Passive aligners of each brand were fitted to one single resin cast prototyped from an STL file from a single patient. The samples obtained were examined under high-resolution micro-CT, and the resulting tomographic microphotographs and volumetric data were compared. 3D analysis investigated the gap volume, the mean gap width and the maximum gap width of each sample. A total of 204 linear 2D measurements were made on 18 microtomographic images to investigate the aligner gap and thickness among different systems. Investigated regions were the central incisor, canine and first molar. The resulting measurements were analysed by ANOVA and compared using Tukey's post hoc analysis (P < 0.05). Results: 3D analysis revealed that the F22 displayed lower gap volume and mean gap width, followed by Airnivol and Invisalign, whereas Airnivol the lowest maximum gap width. 2D analysis showed that F22 had the lowest mean gap and aligner thickness at all teeth investigated. Comparison of the 2D point values revealed statistically significant differences between brands in terms of both measurements (P < 0.05), with the exception of six points in the gap analysis and one in the thickness analysis. Conclusions: There are differences between the six aligner systems examined in terms of 2D and 3D measurements of aligner thickness and gap.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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MicroCT X-ray comparison of aligner gap and thickness of six brands of aligners: an in-vitro study

et al. 2020

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“…Our results demonstrate that attachments on active units are actively involved in producing tooth movement, since in the ATT 3-7 configuration, the maximum stress area is located on the buccal surface of the attachment, differently from other configurations where the active area is located on gingival surfaces of aligners. Aligner fitting depends on the selected material and the thermoforming technique [17]. However, the aligners' gingival margin is known to be the most elastic section of the aligner and, consequently, the one with more chances to lose fitting [18].…”

Section: Discussionmentioning

confidence: 99%

Upper Second Molar Distalization with Clear Aligners: A Finite Element Study

et al. 2020

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Among orthodontists and scientists, in the last years, upper molar distalization has been a debated topic in the orthodontic aligner field. However, despite that few clinical studies have been published, no insights on aligners’ biomechanics regarding this movement are available. The aim of this study was to assess, through finite element analysis, the force system resulting in the upper arch during second maxillary molar distalization with clear aligners and variable attachments settings. The average tooth distalization was found to be 0.029, with buccal flaring of the upper incisors in all attachment configurations. The mesial deformation of the aligner was registered to be 0.2 mm on average. Different pressure areas on the interface between aligners and upper molars were registered, with the mesial attachment surface to be directly involved when present. Periodontal ligament pressure was reported to range between 67 g/cm2 and 132 g/cm2. Configurations with rectangular attachments from second molar-to-canine and from first molar-to-canine present, in an in silico environment, almost equal efficiency in distalizing the upper second molar. However, attachments from the second molar to the canine are suggested to be adopted in clinical environments due to greater feasibility in everyday practice.

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“…For patients with unilateral mastication, the occlusal function of the functional side is greater than that of the opposite side. When eating with the appliance inserted, the aligner on the functional side ts more closely with the tooth surface [30], and the difference between the actual tooth movement and the prescription value is smaller. Therefore, the attachment loss rate is also lower than opposite side.…”

Section: Mastication Habitmentioning

confidence: 97%

Risk Factors of Composite Attachment Loss During Orthodontic Clear Aligner Therapy

Chen¹,

Mohamed²,

Wang³

et al. 2020

Preprint

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Background The composite attachment loss during orthodontic clear aligner therapy is an adverse event that commonly happens in our daily practice. However, there is a lack of related statistical analysis, and studies analyzing the related risk factors. Therefore, the aim of this study is to assess the incidence of attachment loss during orthodontic clear aligner therapy and to identify rick factors that may predict such event.Methods The demographics and clinical variables of 94 patients undergoing clear aligner therapy (27 males and 67 females; average age: 27.60± 0.86 years) were recorded. Both patient-related and tooth-related attachment loss was recorded. The chi-square test and logistic regressive analysis were applied to identify the potential risk factors. SPSS for Mac (version 23.0, IBM, USA) was used for statistical analyses. P＜0.05 was considered statistically significant. Results Our study suggested that the risk factors for attachment loss include: frequent aligner removal (>= 5 times a day) (losing rate=60.0%, P=0.005); aligner wear time less than 18 hours a day (losing rate=50.8%, P=0.014); eating without aligners inserted (losing rate=47.9%, P=0.034); utilizing aligner tray seaters (losing rate=48.2%, P=0.006) and unilateral mastication (losing rate=52.1%, P=0.002). The multivariable logistic regression analysis indicates that aligner wear time less than 18 hours a day (P=0.020, B=0.925), using aligner tray seaters (P=0.007, B=1.168) and unilateral mastication (P=0.034, B=-0.458) were considered independent factors that can predict the composite attachment loss in orthodontic clear aligner therapy.Conclusion Wearing aligner less than 18 hours a day, using aligner tray seaters and unilateral mastication may contribute to increased incidence of composite attachment loss during orthodontic clear aligner therapy.

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Scanning electron microscopy evaluation of aligner fit on teeth

Abstract: 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.

Cited by 29 publications

References 19 publications

MicroCT X-ray comparison of aligner gap and thickness of six brands of aligners: an in-vitro study

MicroCT X-ray comparison of aligner gap and thickness of six brands of aligners: an in-vitro study

Upper Second Molar Distalization with Clear Aligners: A Finite Element Study

Risk Factors of Composite Attachment Loss During Orthodontic Clear Aligner Therapy

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