The science behind the Invisalign® smile

Yes, the Invisalign® System has been shown to be effective in extraction treatments. Since 2011, 233,000 bicuspid extraction (premolar extraction) patients have been treated with Invisalign® clear aligners (Data on file at Align Technology, as of October 20th, 2019) and, in 2016, the First Premolar Extraction Solution (Invisalign® aligners with G6 protocol) designed for maximum anchorage was released for improved clinical results. Several studies, including a prospective study of more than 150 patients and multiple case studies published in scientific journals, have shown that Invisalign® aligners can close space effectively after incisor or premolar extraction, with good root angulation.

A prospective comparative study comparing braces with Invisalign® aligners in more than 152 patients, and a retrospective case-controlled study recently published in a peer-reviewed scientific journal indicates that Invisalign® aligners are as effective in moving teeth as fixed oral appliances.

A retrospective clinical study to assess the efficacy and efficiency of treatment in teen patients with mild malocclusions, comparing outcomes using clear aligners to fixed appliances showed that even though both presented equivalent results, the clear aligner treatment showed significantly improved results in terms of tooth alignment, occlusal relations, and overjet. Assessment of the number of appointments, number of emergency visits, and overall treatment time showed better outcomes for treatment with clear aligners. (Borda et al 2020)

Borda AF, Garfinkle JS, Covell DA, Wang M, Doyle L, Sedgley CM. Outcome assessment of orthodontic clear aligner vs fixed appliance treatment in a teenage population with mild malocclusions. Angle Orthod. 2020 Jul 1;90(4):485-490.

Prospective case-control study enrolled 24 patients seeking for treatment for malocclusions involving severe dental crowding and arch-length discrepancies. (11 male and 13 female, patients’ age was not specified) Inclusion criteria were permanent dentition, growth completion, severe crowding or bimaxillary malocclusion, and no previous orthodontic treatment. Exclusion criteria were clefts or dentofacial deformities, orthognathic surgical treatment plans, and inadequate oral hygiene. The four first premolars would be extracted in each patient. The test group (Invisalign® clear aligners) and the control group (fixed appliances) each consisted of 12 patients. Invisalign® patients: aligner wear: 2 weeks. Invisalign® aligners with G6 protocol required a mean 2.1 years (35 ± 5 aligners) plus a maximum of seven months for refinement/additional aligners (mean 16.5 aligners; range 15-18). The mean treatment time with fixed appliances was 2 years. (Invisalign® treatment time was based on 2-week wear). All patients received acceptable OGS (Objective grading score) after treatment and were completely satisfied with their results. Invisalign® clear aligners and fixed appliances produced comparable outcomes in terms of skeletal, dental, and facial variables, and acceptable soft tissue profiles were achieved in both groups. Overall, both approaches yielded satisfactory results, including space closure and effective anchorage control.

Gaffuri, Francesca & Cossellu, Gianguido & Lanteri, Valentina & Brotto, Elisabetta & Farronato, Marco. Comparative Effectiveness of Invisalign® and Fixed Appliances in First Premolar Extraction Cases. Journal of Clinical Orthodontics: JCO May 2020. LIV. 294-301.

A retrospective study of 2 groups of 50 adult patients with overbite larger than 5.0 mm and 60% deep (25 for Invisalign® aligners and 25 for fixed appliance) showed that both Invisalign® clear aligners and conventional fixed appliances were effective in treating patients with a severe deep overbite. Invisalign® treatment may be preferable over conventional fixed appliance therapy in patients with high angle and deep overbite.

Fujiyama K, Kera Y, Yujin S, Tanikawa C, Yamashiro T, Guo X, Ni A, Deguchi T. Comparison of clinical outcomes between Invisalign and conventional fixed appliance therapies in adult patients with severe deep overbite treated with nonextraction. Am J Orthod Dentofacial Orthop. 2022 Apr;161(4):542-547. Doi: 10.1016/j.ajodo.2020.08.023. Epub 2021 Oct 8. PMID: 34629236.

In this retrospective study, two treatment groups of adult (≥18 years old) hyperdivergent patients (mandibular plane angles of ≥38°) with anterior open bites were included: 17 fixed appliance patients and 36 clear aligner patients. Thirteen cephalometric measurements representing the vertical dimension were reported for each group. A two-sample t-test was used to assess differences in changes in mandibular plane angle and overbite between the two treatment groups. There were no statistical differences found in the magnitude of overbite correction and the changes in any of the cephalometric measurements for vertical control. The clear aligner group showed a slightly greater amount of lower incisor extrusion (P = .009). The main mechanism of open bite correction was similar between the two treatment groups and was accomplished through retroclination of the upper and lower incisors while maintaining the vertical position of the upper and lower molars. Cephalometric comparison of anterior open bite correction and changes in the mandibular plane angle associated with use of clear aligners and fixed appliances did not demonstrate statistically significant differences in adult hyperdivergent patients.

Shen Garnett B, Mahood K, Nguyen M, Al-Khateeb, A, Liu S, Boyd R, Oh H. Cephalometric comparison of adult anterior open bite treatment using clear aligners and fixed appliances. Angle Orthod 2019 Jan;89(1):3-9.

Yes, since 2011, over 372,000 Class II patients have been treated with Invisalign® clear aligners. *Data on file at Align Technology, as of as of October 20th, 2019). In addition, multiple case studies published in peer-reviewed scientific journals indicate that the Invisalign® System is effective in the treatment of Class II malocclusions.

A prospective study aimed to compare the predictability of maxillary molar distalization. The sample included 142 maxillary molar teeth (71 first molar, 71 second molar) measured from the digital models of 38 participants (4 male, 34 females, age range from 17 years to 39 years). Results of the current study indicated that Invisalign® treatment could be used successfully for adult patients requiring 2.6mm of maxillary molar distalization.

Saif BS, Pan F, Mou Q, Han M, Bu W, Zhao J, Guan L, Wang F, Zou R, Zhou H, Guo YC. Efficiency evaluation of maxillary molar distalization using Invisalign® aligners based on palatal rugae registration. Am J Orthod Dentofacial Orthop. 2022 Apr;161(4):e372-e379.

A two-centre retrospective study of 20 non-growing patients who underwent bilateral sequential distalization of their maxillary dentition with Invisalign® aligners compared pre- and post-treatment lateral cephalograms. The orthodontic intervention was planned following the maxillary molar distalization protocol proposed by Align Technology in order to obtain sequential distalization on the upper arch with staging of 0.25mm per aligner. Intermaxillary Class II elastics were used to prevent loss of anchorage and thus possible flaring of anterior teeth. Rectangular vertical attachments were placed on distalized teeth to control the distalization movement. Interproximal reduction was not applied. The study demonstrated that, after an average treatment period of 24.3 ± 4.2 months, distalization of maxillary molars was successfully accomplished in non-growing patients without significant mesiodistal tipping or vertical movements, nor changes in the facial height. (Ravera et al 2016).

Giulia Gay, Serena Ravera, Tommaso Castroflorio, Francesco Garino, Gabriele Rossini, Simone Parrini , Giovanni Cugliari , Andrea Deregibus. Root resorption during orthodontic treatment with Invisalign®: a radiometric study. Prog Orthod. 2017 Dec;18(1):12. doi: 10.1186/s40510-017-0166-0. Epub 2017 May 15. PMID: 28503724; PMCID: PMC5430001.

A retrospective study done to analyse the effects on vertical dentoskeletal dimension of young adults treated with sequential distalization with aligners concluded that upper molar distalization with aligners provide good control of the vertical dimension representing a good solution for the treatment of hyperdivergent or open bite subjects. It also allows an excellent control of the incisal torque without loss of anchorage during the orthodontic procedure.
Caruso S, Nota A, Ehsani S, Maddalone E, Ojima K, Tecco S. Impact of molar teeth distalization with clear aligners on occlusal vertical dimension: a retrospective study. BMC Oral Health. 2019 Aug 13;19(1):182. doi: 10.1186/s12903-019-0880-8. PMID: 31409348; PMCID: PMC6692944.

Yes, peer-reviewed studies showing efficacy of mandibular advancement feature have been published in scientific journals.

A prospective case-controlled study to evaluate the dentoskeletal effects of the Invisalign® Mandibular Advancement (MA) feature in skeletal Class II growing patients with mandibular retrusion, at pre-pubertal and pubertal stages. In pre-pubertal stage, changes were primarily dentoalveolar. During the pubertal growth spurt, changes were dentoskeletal. When MA applied during the pubertal growth spurt, the appliance promotes a significant additional growth of the mandible and treatment during the pubertal spurt produces skeletal effects with an annual rate of change of 5.8 mm (comparable to what has been previously described for the Twin Block appliance).

Ravera S, Castroflorio T, Galati F, Cugliari G, Garino F, Deregibus A, Quinzi V. Short term dentoskeletal effects of mandibular advancement clear aligners in Class II growing patients. A prospective controlled study according to STROBE Guidelines. Eur J Paediatr Dent. 2021 Jun;22(2):119-124. doi: 10.23804/ejpd.2021.22.02.6. PMID: 34238001.

A prospective, multicenter clinical study was done to test the safety and effectiveness of Invisalign mandibular advancement appliance in growing patients with Class II malocclusions. A total of 60 subjects were enrolled; 55% were male and 45% were female patients. Mean age was 12.75 years at the start of treatment (13.11 for males and 12.15 for females). Inclusion criteria: fully erupted dentition (not including second premolars and second and third molars) with bilateral Class II malocclusions of at least 3mm. The mean time from the initiation of treatment (T1) to the end of the MA phase (T2) was 12.6 months, and the mean time from T1 to the end of the post-MA phase (T3)—representing the mean total treatment time—was 25.6 months. During the MA phase (T1 to T2), only the MA appliance was used, with no elastics or other auxiliaries. In the post-MA phase (T2 to T3), Class II elastics were used in 90% of the cases. Findings: the primary mechanism of action of functional appliances in achieving Class II correction is dentoalveolar, with a smaller component of skeletal change. While subjects generally experienced a correction from a Class II to a Class I relationship, skeletal changes were consistent with the concept of a lesser component of “growth modification” than of dentoalveolar changes within the overall occlusal correction. Since no Class II elastics or other auxiliaries were used during the MA phase (T1 to T2); it is reasonable to attribute the cephalometric and linear changes noted at T2 to the effects of the MA appliance, along with normal growth. After the MA phase, significant changes were observed at T3 such as reduction in overbite and overjet and an improvement in the molar relationship. There was no significant change in the mandibular plane angle and excellent control of lower-incisor angulation. Even though Invisalign treatment with MA seems to produce similar treatment results (compared to other know MA appliances), it offers several advantages over traditional Class II functional appliances. For example: mandibular incisor angulation and molar extrusion are well controlled, and patients rate their degree of discomfort as low.
Glaser BJ, Tai SK, Blevins R, Daher S. Prospective multicenter investigation of Invisalign treatment with the mandibular-advancement feature: An interim report. J Clin Orthod. 2022 Aug;56(8):458-463. PMID: 36572046.

Yes, peer-reviewed studies showing efficacy of Invisalign First™ have been published in scientific journals.

A retrospective study of 20 patients, 12 females and 8 males, was done to evaluate maxillary arch changes in patients treated with Invisalign® First™ system in mixed dentition, focusing on arch width, arch perimeter, arch depth, molar inclination and alveolar expansion. Arch widths, arch perimeter, arch depth and molar inclination were measured on pre-treatment and post-treatment digital dental models. Superimposition of digital models was performed to evaluate alveolar expansion. Intercanine width showed an average increase of 2.8 mm at cusp tips, first deciduous molars, an average increase of 3.28 mm at cusp tip level, second deciduous molars, an average increase of 3.72 mm and for the upper first permanent molars, the amounts of expansion achieved at cuspid level was 3.05 mm. The main advantages of this treatment lie in its comfort and aesthetics, in the reduction of the risk of additional appointments and in the better oral hygiene compared to fixed appliances. It was concluded that in cases of mild crowding or limited transverse maxillary deficiency, Invisalign® First™ clear aligners could be a reasonable alternative to traditional slow maxillary expanders.

Levrini L, Carganico A, Abbate L. Maxillary expansion with clear aligners in the mixed dentition: A preliminary study with Invisalign® First system. Eur J Paediatr Dent. 2021 Jun;22(2):125-128. doi: 10.23804/ejpd.2021.22.02.7. PMID: 34238002.

A case study of three cases treated with the Invisalign® First™ system in which the patients provide a good representation of Phase I therapeutic needs, including an anterior crossbite. The cases are all well documented and well treated, and the author offers numerous tips and techniques gleaned from her experience with some of the earliest Invisalign® First™ cases. (Blevins, 2019)

Blevins R. Phase I orthodontic treatment using Invisalign First. J Clin Orthod. 2019 Feb;53(2):73-83. PMID: 30978720.

A total of 23 patients (13 female and 10 male, average age of 8.3 ± 1.0 years old.) with interceptive orthodontic malocclusion were selected for orthodontic treatment with Invisalign ® First™ and were examined over 18 months (Phase 1). Measurements taken at the beginning and end of the treatment were compared. All treatment objectives were achieved within 18 months, except for two Class II cases, with 69% of them solved with the first set of aligners. Additional aligners were used in the remaining cases. It was concluded that the Invisalign ® First™ (Phase 1) may be effective in most interceptive problems. The interceptive treatment with Invisalign® First™ system is effective in growing patients, being capable of producing clinical results within 18 months. High treatment compliance was observed with Invisalign clear aligners.

Pinho T, Rocha D, Ribeiro S, Monteiro F, Pascoal S, Azevedo R. Interceptive Treatment with Invisalign® First in Moderate and Severe Cases: A Case Series. Children (Basel). 2022 Aug 5;9(8):1176. doi: 10.3390/children9081176. PMID: 36010067; PMCID: PMC9406487.

A prospective study was done to evaluate the transverse maxillary arch development with the Invisalign® First™ system® in growing subjects. 23 patients were selected for this study (9 females, 14 males, mean age 9.4 ± 1.2 years). Patients were treated nonextraction with Invisalign First™ system® clear aligners with no auxiliaries other than Invisalign® attachments. The ClinCheck® for each patient was planned with the same standardized expansion protocol: sequential staging pattern for upper arch expansion, “molars move first”, followed by simultaneous expansion of all posterior deciduous teeth and canines. The amount of arch expansion was of 0.15mm per stage. It was concluded that the greatest increase of maxillary width was detected at the level of the upper first deciduous molars, followed by the level of the second deciduous molars and by the deciduous canines. Therefore, The Invisalign First™ system® can be considered effective in growing patients who require maxillary arch development and dentoalveolar expansion. Treatment adherence was good/moderate in all treated patients.

Lione R, Cretella Lombardo E, Paoloni V, Meuli S, Pavoni C, Cozza P. Upper arch dimensional changes with clear aligners in the early mixed dentition: A prospective study. J Orofac Orthop. 2023 Jan;84(1):33-40. English. doi: 10.1007/s00056-021-00332-z. Epub 2021 Sep 3. PMID: 34477905.

A retrospective study was done to compare palatal dimensions and molar inclinations after Invisalign First System (IFS) to those patients treated with slow maxillary expansion (SME) and normal controls. 23 patients (11 males and 12 females, ages between 8-11) with mixed dentition were selected and matched in age and gender with the other 2 groups. In the IFS group, all patients were planned with the same sequential staging expansion protocol, with molars first followed by the simultaneous expansion of deciduous molars and canines. All patients were instructed to change their aligners every week. The mean number of aligners was 28. The duration between the initial and refinement was +-0.36 years. The treatment length of SME was 0.98 +- 0.51 years. It was concluded that IFS produced significant increases in the upper arch expansion with increased intercanine width and intermolar width compared to controls, but the expansion amount is smaller than SME. Unlike SME, IFS has no effects on palatal dimensions and molar inclinations.

Wang J, Bukhari A, Tai SK, Zou B. Dimensional changes in the palate associated with Invisalign First System: a pilot study. Angle Orthod. 2023 Apr 13. doi: 10.2319/110422-755.1. Epub ahead of print. PMID: 37052464.

Yes, multiple case studies published in peer-reviewed scientific journals indicate that the Invisalign® System can be used to treat Class III malocclusions effectively.

A 32-year-old female, with Class III incisor relationship on a Class III skeletal base, was treated with lower right central incisor extraction followed by Invisalign® aligners. The objective was to maintain the Class III molar relationships and improve the overbite. Total treatment time was 16 months and Class III elastics were required. Treatment resulted in well-aligned arches, with positive overjet and improved overbite. Bodily tooth movement was confirmed by panoramic radiograph with the roots of the remaining lower incisors almost completely parallel.

Needham R, Waring DT, Malik OH. Invisalign treatment of Class III malocclusion with lower-incisor extraction. J Clin Orthod. 2015 Jul;49(7):429-41. PMID: 26267545.

Yes, since 2011, over 97,000 moderate to severe open bite patients have been treated with Invisalign clear aligners (Data on file at Align Technology, as of October 20th, 2019). In addition, a retrospective study and several case studies published in peer-reviewed scientific journals indicate that the Invisalign® System can be used to treat open bite effectively.

Retrospective clinical study of 45 patients with open bite, showed that clear aligners are effective in reducing/controlling the vertical dimension in open bite patients due to a combination of maxillary and mandibular incisor extrusion and maxillary and mandibular molar intrusion, with slight mandibular auto rotation.

Harris K, Ojima K, Dan C, Upadhyay M, Alshehri A, Kuo CL, Mu J, Uribe F, Nanda R. Evaluation of open bite closure using clear aligners: a retrospective study. Prog Orthod. 2020 Aug 24;21(1):23. doi: 10.1186/s40510-020-00325-5. PMID: 32830306; PMCID: PMC7443419.

A multi-center retrospective study of 30 adult patients to evaluate, by means of cephalometric appraisal, the vertical effects of non-extraction treatment of adult anterior open bite with clear aligners (Invisalign® System), concluded the Invisalign system is a viable therapeutic modality for non-extraction treatment of adult anterior mild open bites. Bite closure was mainly achieved by a combination of counterclockwise rotation of the mandibular plane, lower molar intrusion and lower incisor extrusion.

Moshiri S, Araújo EA, McCray JF, Thiesen G, Kim KB. Cephalometric evaluation of adult anterior open bite non-extraction treatment with Invisalign. Dental Press J Orthod. 2017 Sep-Oct;22(5):30-38. doi: 10.1590/2177-6709.22.5.030-038.oar. PMID: 29160342; PMCID: PMC5730134.

In a multicenter retrospective study, overbite changes were assessed in 120 adult patients treated between 2010 and 2014 only with Invisalign® aligners only, including 12 patients with mild to moderate open bite. Cephalometric analyses indicated that Invisalign® aligners improved the overbite in these patients with a median deepening of 1.5mm. Overbite correction was mainly accomplished by extrusion of the maxillary and mandibular incisors. The use of attachments to extrude incisors was a common strategy among the study orthodontists. No significant changes were observed in posterior vertical dimension or mandibular plane angle. Furthermore, the results from the 68 patients with normal overbite included in this study suggest that the Invisalign® System is successful in maintaining the anterior and posterior vertical dimension in patients with normal overbite and contradict the notion among some orthodontists that Invisalign® aligners deepen the bite by intruding posterior teeth.

Khosravi R, Cohanim B, Hujoel P, Daher S, Neal M, Liu W, Huang G. Management of overbite with the Invisalign appliance. Am J Orthod Dentofacial Orthop. 2017 Apr;151(4):691-699.e2. doi: 10.1016/j.ajodo.2016.09.022. PMID: 28364892.

Yes, since 2011, over 1,533,000 moderate to severe deep bite patients have been treated with Invisalign® clear aligners. (*Data on file at Align Technology, as of October 20th, 2019). In addition, a multicenter retrospective study and several case studies published in peer-reviewed scientific journals indicate that the Invisalign® System can be used to treat deep bite effectively.

A retrospective study was done to evaluate and compare levelling of the curve of Spee achieved by traditional fixed appliances and Invisalign® clear aligners. Invisalign® clear aligner group included 30 subjects (13 males, 17 females; mean age, 24 years 5 months +- 19 months). The fixed appliance group included 32 subjects (12 males, 20 females; mean age, 22 years 4 months +- 21 months). It was concluded that traditional continuous archwire treatment and the Invisalign® System effectively level the curve of Spee, the full-fixed appliance group presented a statistically significant extrusion of posterior teeth, with a flaring of the mandibular incisors. The Invisalign® aligner group showed a statistically significant intrusion of the mandibular incisors, with excellent control in the proclination of incisors during the intrusion movement.

Rozzi M, Giulia Tiberti,a Manuela Mucedero,a and Paola Cozza. Leveling the curve of Spee: Comparison between continuous arch wire treatment and Invisalign® System: A retrospective study. American Journal of Orthodontics and Dentofacial Orthopedics. August 2022 (Online) November 2022 Vol 162 Issue 5

Yes, case studies published in peer-reviewed scientific journals indicate that the Invisalign® System can be used to treat crossbite effectively.

In adult patients, treatment of skeletal crossbite requires combined treatment by fixed or removable appliances and orthognathic surgery. In cases of dentoalveolar crossbite, expansion can be achieved with fixed multibrackets and removable transparent aligners. Various researchers have already assessed the Invisalign system's predictability for arch expansion. A sample of 114 patients with transverse malocclusion were treated with SmartTrack. The predictability of the system's software (ClinCheck®) was assessed by comparing planned measurements (width of canines, premolars and molars rotations and inclinations) with the real measurements achieved at the end of the first treatment phase. Measurements were imported to ClinCheck software to create three data sets; T1: initial measurements at start of treatment; T2: ClinCheck predicted measurements at end of first treatment phase; T3: measurements taken at start of the second treatment phase. All the treatment plan's estimations, with the exception of the second molar, were significantly higher than the actual outcomes. Aligners are an effective tool for producing arch expansion, being more effective in premolar area and less effective in canine and second molar area

Morales-Burruezo, Ignacio & Gandia Franco, Jose & Cobo, Juan & Vela-Hernández, Arturo & Bellot-Arcis, Carlos. Arch expansion with the Invisalign® System: Efficacy and predictability. (2020). PLOS ONE. 15. e0242979. 10.1371/journal.pone.0242979.

Yes, Invisalign® aligners can rotate teeth effectively, while the use of Optimized Attachments can improve the efficacy of tooth rotations.

A retrospective study of 30 patients (aged 13−72 years) demonstrated that significantly higher forces can be achieved by using Optimized Rotation attachments. Attachments were associated with substantial differences in the measured movements of the premolar derotation group, especially in teeth with short crowns and undercuts.

Simon M, Keilig L, Schwarze J, Jung BA, Bourauel C. Forces and moments generated by removable thermoplastic aligners: incisor torque, premolar derotation, and molar distalization. Am J Orthod Dentofacial Orthop. 2014 Jun;145(6):728-36. doi: 10.1016/j.ajodo.2014.03.015. Erratum in: Am J Orthod Dentofacial Orthop. 2014 Oct;146(4):411. PMID: 24880843.

In a finite element study to evaluate the orthodontic rotational movement of a lower second premolar obtained with clear aligners, analysing different staging and attachment configurations concluded that the model with a single attachment and 1.2 degrees of aligner activation was the most efficient.

Cortona A, Rossini G, Parrini S, Deregibus A, Castroflorio T. Clear aligner orthodontic therapy of rotated mandibular round-shaped teeth: A finite element study. Angle Orthod. 2020 Mar;90(2):247-254. doi: 10.2319/020719-86.1. Epub 2019 Aug 30. PMID: 31469592; PMCID: PMC8051248.

Yes, case studies published in peer-reviewed scientific journals indicate that the Invisalign® System can be used to expand arches effectively.

A retrospective clinical study in 19 patients (16 females and 3 males, 15 to 50 years of age) that required expansion with Invisalign® aligners. For this study, in the 19 selected patients, the upper first and upper second premolars were analyzed. Clinical and tomographic measurements were taken before beginning expansion treatment and at 12 months. The average expansion was 1.93 mm (range 0.5 to 5.1 mm) for first premolar and 1.67 mm (range 0.3 to 3.9 mm) for second premolar. Seventy-six teeth (n=76), corresponding to upper 1^st premolar and 2^nd premolar were evaluated in the 19 patients. At the end of the study, it was also concluded that during the first year of Invisalign® treatment for expansion movements did not produce substantial changes in the evaluated periodontal clinical parameters (plaque index, gingival index, pocket depth, and clinical attachment level) or in the bone level measurements. Removable appliances reduce plaque retentive factors and encourage adequate oral hygiene.

Barreda GJ, Dzierewianko EA, Mazza V, Muñoz KA, Piccoli GI, Romanelli HJ. Expansion treatment using Invisalign® System: Periodontal health status and maxillary buccal bone changes. A clinical and tomographic evaluation. Acta Odontol Latinoam. 2020 Sep 1;33(2):69-81. English. PMID: 32920608.

Yes, since 2011, 1,900,000 patients with complex cases, including Class II, open bite, premolar extraction, and deep bite, have been treated with Invisalign® aligners (Data on file at Align Technology, as of October 20th, 2019). The Invisalign® System can be used in conjunction with auxiliaries, or with surgery, to correct highly complex conditions. Multiple case studies published in peer-reviewed scientific journals indicate that Invisalign® aligners can be used to treat complex cases effectively.

A multi-center retrospective study in 30 adult patients (22 females, 8 males; mean age at start of treatment: 28 years and 10 months; mean anterior open bite at start of treatment: 1.8 mm) anterior mild open bite patients treated with Invisalign that were finished between 2011 and 2015 were retrospectively collected from three orthodontic private practices. Sample consisted of 24 Angle Class I patients and 6 Angle Class II patients. No patient presented crowding exceeding 6 mm either in the maxillary or in the mandibular dental arch. 24 practice A, 4 practice B, 2 practice C. Statistically significant (p< 0.01) changes were found in SN-MxOP, SN-MnOP, MP-MnOP, SN-MP, SN-GoGn, LAFH, overbite, and L1-MP. Statistically significant (p< 0.05) changes were also observed in L6-MP. But SN-PP, U1-PP, and U6-PP did not undergo any statistically significant changes. Average treatment time was 21 months (ranging from 11 to 34 months). Bite closure was mainly achieved by a combination of counterclockwise rotation of the mandibular plane, lower molar intrusion and lower incisor extrusion.

Moshiri S, Araujo EA, McCary JF, Thiesen G, Kim KB. Cephalometric evaluation of adult anterior open bite non-extraction treatment with Invisalign® aligners. Dental Press J Orthod 2017 Sep-Oct; 22(5): 30-38

Yes, since 2001, over 3,000,000 teenager patients (age 19 or younger) have been treated with the Invisalign® System. (Data on file at Align Technology, as of September 30, 2021). Multiple case studies published in peer-reviewed scientific journals indicate that the Invisalign® System can treat malocclusions in teenagers effectively. Invisalign® aligners are accepted by teenagers as a more aesthetic option compared with wires and brackets (Walton et al, 2010). Compliance is critical in teenager treatments. Close monitoring is recommended to check erupting teeth are moving as planned.

A retrospective study assessed the outcomes of orthodontic treatment in teens with mild malocclusions, comparing results achieved with clear aligners to those achieved with fixed appliances. It was concluded that treatment with clear aligners for mild malocclusions resulted in significantly better results in terms of the assessments of tooth alignment, occlusal relations, overjet, and overall CRE (Cast-Radiograph Evaluation) scoring. Regarding treatment efficiency, treatment with aligners showed more favorable outcomes for treatment duration, number of emergency visits, and number of overall appointments.

Borda AF, Garfinkle JS, Covell DA, Wang M, Doyle L, Sedgley CM. Outcome assessment of orthodontic clear aligner vs fixed appliance treatment in a teenage population with mild malocclusions. Angle Orthod. 2020 Jul 1;90(4):485-490. doi: 10.2319/122919-844.1. PMID: 33378505; PMCID: PMC8028462.

Yes, Invisalign® aligners are associated with good oral hygiene procedures and help provide better periodontal health in teenagers. In addition, the Invisalign® System is associated with less pain^* in the initial stages of treatment than fixed appliances, thus promoting a good quality of life.

^*In a survey of patients age 13-18 rating on a scale of 1-9, with 1 as 'extremely painful' and 9 as 'not at all painful', traditional metal braces patients (n=141) rated 5.1, while Invisalign patients (n=106) rated pain lower at 6.5. Data on file at Align Technology, December 28, 2022.

During 12 months of orthodontic therapy, teenagers (teenager patients) treated with Invisalign® clear aligners demonstrate better compliance with oral hygiene and present less plaque and gingival inflammatory reactions than their peers with fixed appliances.^*

^*Based on significantly lower Plaque Index (PI), probing depth (PD), and Bleeding on Probing (BOP) of the upper right first molar and upper left central incisors at initial, 3,6, and 12 months as well as full month plaque score (FMPS) and full mouth bleeding score (FMBS) score at initial and 12 months and better higher compliance with oral hygiene on 50 teenager patients (age 10-18, 25 invisalign treatment, 25 fixed appliances).

Abbate GM, Caria MP, Montanari P, Mannu C, Orrù G, Caprioglio A, Levrini L. Periodontal health in teenagers treated with removable aligners and fixed orthodontic appliances. J Orofac Orthop. 2015 May;76(3):240-50. doi: 10.1007/s00056-015-0285-5. PMID: 25929710.

As shown in multiple studies recently published in peer-reviewed scientific journals, the Invisalign® System can be considered as a useful tool for pre-restorative treatments.

A prospective, longitudinal cohort study involving 60 adult orthodontic patients (33 with Invisalign aligners, 27 with fixed appliances) was completed by using a daily diary to measure treatment impacts including functional, psychosocial, and pain-related outcomes. A baseline survey was completed before the start of treatment; diary entries were made for 7 consecutive days to measure various impacts of the subjects' orthodontic treatment over time. The data were then analyzed for differences between treatment modalities in terms of the subjects' reported impacts from their orthodontic treatment.

Miller KB, McGorray SP, Womack R, Quintero JC, Perelmuter M, Gibson J, Dolan TA, Wheeler TT. A comparison of treatment impacts between Invisalign aligner and fixed appliance therapy during the first week of treatment. Am J Orthod Dentofacial Orthop. 2007 Mar;131(3):302.e1-9. doi: 10.1016/j.ajodo.2006.05.031. PMID: 17346581.

The aim of this prospective study was to compare the periodontal health and the microbiological changes via real-time polymerase chain reaction (PCR) in adult patients treated with fixed orthodontic appliances and Invisalign® System. Concluded patients undergoing orthodontic treatment with the Invisalign® System show a superior periodontal health in the short-term when compared to patients in treatment with fixed orthodontic appliances. Invisalign should be considered as a first treatment option in patients with risk of developing periodontal disease.

Levrini L, Mangano A, Montanari P, Margherini S, Caprioglio A, Abbate GM. Periodontal health status in patients treated with the Invisalign(®) system and fixed orthodontic appliances: A 3 months clinical and microbiological evaluation. Eur J Dent. 2015 Jul-Sep;9(3):404-410. doi: 10.4103/1305-7456.163218. PMID: 26430371; PMCID: PMC4569994.

Yes, treatment with Invisalign® clear aligners is completed 5 months faster on average than treatment with fixed appliances. (Buschang et al, 2014, Gu et al, 2017). This was demonstrated in a retrospective case-controlled study of Invisalign® aligners versus conventional fixed appliances in 48 patients with mild-to-moderate malocclusion. While being equally effective as fixed oral appliances in the treatment of orthodontic conditions, treatment with Invisalign® aligners is associated with the ability to better maintain oral hygiene, better periodontal health, increased quality of life, and less pain in the initial stages of treatment than fixed oral appliances, as shown in multiple studies published in peer-reviewed journals.

A controlled retrospective study compared the time efficiency of 150 conventional edgewise braces cases and 150 aligner therapy (Invisalign® System) cases matched based on mandibular crowding and number of rotated teeth. The results of this study showed that Invisalign® patients required significantly fewer visits to the orthodontist (approximately four), shorter treatment duration (5.5 months shorter), fewer emergency visits, and less total chair time (93.4 minutes) than patients treated with conventional edgewise braces.

Buschang PH, Shaw SG, Ross M, Crosby D, Campbell PM. Comparative time efficiency of aligner therapy and conventional edgewise braces. Angle Orthodontist, Vol 84, No 3, 2014

A retrospective case-control study was to compare the treatment effectiveness and efficiency of the Invisalign system with conventional fixed appliances in treating orthodontic patients with mild to moderate malocclusion in a graduate orthodontic clinic. Data showed that both Invisalign and fixed appliances were able to improve the malocclusion. Invisalign patients finished treatment faster than did those with fixed appliances.

Gu J, Tang JS, Skulski B, Fields HW Jr, Beck FM, Firestone AR, Kim DG, Deguchi T. Evaluation of Invisalign treatment effectiveness and efficiency compared with conventional fixed appliances using the Peer Assessment Rating index. Am J Orthod Dentofacial Orthop. 2017 Feb;151(2):259-266. doi: 10.1016/j.ajodo.2016.06.041. PMID: 28153154.

A retrospective study assessed the outcomes of orthodontic treatment in teens with mild malocclusions, comparing results achieved with clear aligners to those achieved with fixed appliances concluded that treatment with clear aligners for mild malocclusions resulted in significantly better results in terms of the assessments of tooth alignment, occlusal relations, overjet, and overall CRE (Cast-Radiograph Evaluation) scoring. Regarding treatment efficiency, treatment with aligners showed more favorable outcomes for treatment duration, number of emergency visits, and number of overall appointments *Invisalign® patients require on average 30% fewer doctor visits than fixed appliance patients.

Borda AF, Garfinkle JS, Covell DA, Wang M, Doyle L, Sedgley CM. Outcome assessment of orthodontic clear aligner vs fixed appliance treatment in a teenage population with mild malocclusions. Angle Orthod. 2020 Jul 1;90(4):485-490. doi: 10.2319/122919-844.1. PMID: 33378505; PMCID: PMC8028462.

In a retrospective study to compare the time efficiency of aligner therapy and conventional braces, 300 patients were evaluated (150 with aligners and 150 with braces). All of the patients had mild-to-moderate Class I malocclusions and were treated with no extraction. It was concluded that conventional braces patients required significantly more visits, a longer treatment duration, more emergency visits, greater emergency chair time, and greater total chair time than aligner therapy. *Invisalign® patients require on average 30% fewer doctor visits than fixed appliance patients. Invisalign® treatment duration was 5month/5.5 months shorter than conventional braces treatment.

Buschang PH, Shaw SG, Ross M, Crosby D, Campbell PM. Comparative time efficiency of aligner therapy and conventional edgewise braces. Angle Orthod. 2014 May;84(3):391-6. doi: 10.2319/062113-466. PMID: 24749702; PMCID: PMC8667515.

No, the current literature suggests that root resorption is similar or less of a problem with aligners. The risk of root resorption is a concern in all orthodontic cases with increased treatment time and, in particular, in cases with greater amounts of tooth movement. Evidence suggests that the incidence and severity of root resorption might be lower with clear aligners, including Invisalign® aligners, than with fixed braces.

A retrospective clinical study was done in 80 non-extraction patients to comparatively evaluate the amount of external apical root resorption in non-extraction patients receiving clear aligner therapy (CAT) or fixed orthodontic treatment (FOT). The overall external apical root resorption in the CAT patients was significantly less than the FOT. Clear aligner therapy may have a superiority of reducing external apical root resorption compared to fixed orthodontic treatment in non-extraction patients.

Yi J, Xiao J, Li Y, Li X, Zhao Z. External apical root resorption in non-extraction cases after clear aligner therapy or fixed orthodontic treatment. J Dent Sci. 2018 Mar;13(1):48-53. doi: 10.1016/j.jds.2017.09.007. Epub 2018 Feb 1. PMID: 30895094; PMCID: PMC6388840.

A retrospective cohort study of 373 roots from 70 subjects (mean age 23.61 ± 7.03 years, 21 males and 49 females) conclude that the prevalence and severity of apical root resorption on CBCT in patients treated with clear aligners was less than those in patients treated with fixed appliances.

Li Y, Deng S, Mei L, Li Z, Zhang X, Yang C, Li Y. Prevalence and severity of apical root resorption during orthodontic treatment with clear aligners and fixed appliances: a cone beam computed tomography study. Prog Orthod. 2020 Jan 6;21(1):1. doi: 10.1186/s40510-019-0301-1. PMID: 31903505; PMCID: PMC6943096.

Our technology, including SmartTrack™ aligner material, attachments, software and manufacturing, sets us apart. The Invisalign® System combines multiple smart innovations designed specifically for treatment of difficult malocclusions, such as open bite, deep bite and first premolar extraction (planned for maximum or moderate anchorage). SmartTrack™ material, when combined with SmartForce™ attachments features and SmartStage™ treatment planning software, allows more predictable tooth movement, compared to Invisalign® aligners previously made from single-layer (EX30) material.

A single-centre randomized clinical trial was done to investigate the effect of SmartTrack™ material on orthodontic tooth movement over a 25-day period, compared with the EX30 material. 33 patients (17 females and 16 males), between 18 and 40 years old were selected to use the aligners 22 h per day for 25 days. It was concluded that SmartTrack™ material achieved a significantly higher mean orthodontic tooth movement (73.1% of planned tooth movement), compared with EX30 (42.8% of planned tooth movement) by day 14. Overall, SmartTrack™ material achieved a higher mean orthodontic tooth movement compared with the EX30 material over a 25-day period.

Wheeler, T., Patel, N., & McGorray, S. Effect of aligner material on orthodontic tooth movement. J.Aligner Orthod. 2017; 1(1):21-27.

Three case reports of adults with pre-restorative concerns that were treated with Invisalign clear aligners were analysed. One a 41-year-old male with a missing molar who wanted to have an implant replacement. A 37-year-old woman that wished to improve the aesthetic look of her smile but did not want a fixed appliance and 34year old male who presented an unpleasant smile. (missing left upper lateral incisor, microdontia of right lateral incisor, and upper midline drifted to the left side). It was concluded, at the end of these reports that the Invisalign clear aligners showed good effectiveness in successfully performing complex adult treatments. All required dental movements were enacted with no relevant counter-effects thanks to high-quality biomechanical features of the aligners. Also, patient satisfaction was recorded as very high, because they underwent an invisible orthodontic treatment and they reached optimal esthetics and, above all, their occlusion was functionally rehabilitated.

Mampieri G, Giancotti A. Invisalign technique in the treatment of adults with pre-restorative concerns. Prog Orthod. 2013 Oct 20;14(1):40. doi: 10.1186/2196-1042-14-40. PMID: 24325954; PMCID: PMC3903075.

Two case reports described the advantages of clear aligner therapy (Invisalign Go™) in interdisciplinary treatments. It was shown that clear aligner therapy is extremely useful in multidisciplinary treatment plan in order to straighten teeth especially in a pre-restorative phase to allow minimally invasive and adhesive restorations.

Weinstein T, Marano G, Aulakh R. Five-to-five clear aligner therapy: predictable orthodontic movement for general dentist to achieve minimally invasive dentistry. BMC Oral Health. 2021 Dec 29;21(1):671. doi: 10.1186/s12903-021-02034-9. PMID: 34965879; PMCID: PMC8717640.