Analysis on Mandibular Anterior Tooth Intrusion with Clear Aligners / 医用生物力学

国家自然科学基金项目(11932012、81400536),上海申康医院发展中心临床创新三年行动计划(SHDC2020CR3009A),上海交通大学医工(理)交叉基金(JYJC202130)

Mandibular advancement with clear aligners and functional appliances in the treatment of skeletal ClassⅡmalocclusion: a systematic review and meta-analysis / 华西口腔医学杂志

OBJECTIVES@#This study aimed to conduct a meta-analysis of the efficacy of mandibular advance clear alig-ners with traditional functional appliances as the control group.@*METHODS@#PubMed, Web of Science, Embase, Cochrane Library, China Biomedical Abstracts Database, China Knowledge Network Database, Wanfang Database, and Weipu Database were used in this study. The two groups of researchers screened the literature and extracted data based on the inclusion and exclusion criteria established by PICOS entries, and used the ROBINS-I scale for quality evaluation. Revman 5.4 and Stata 17.0 software were used for meta-analysis.@*RESULTS@#Nine clinical controlled trials were included in this study with a total sample size of 283 cases. No significant difference was found in SNA, SNB, ANB, Go-Pog, U1-SN, Overjet, and other aspects between the invisible group and the traditional group in the treatment of skeletal class Ⅱ ma-locclusion patients; there was a 0.90° difference in mandibular plane angle between the two groups; the growth of the mandibular ramus (Co-Go) in the traditional group was 1.10 mm more than that in the invisible group; the lip inclination of the lower teeth in the invisible group was better controlled, 1.94° less than that in the control group.@*CONCLUSIONS@#The invisible group can better control the lip inclination of the mandibular anterior teeth when guiding the mandible. Furthermore, the mandibular plane angle (MP-SN) can remain unchanged, but the growth of the mandibular ramus is not as good as the traditional group, and auxiliary measures should be taken to improve it in clinical practice.

Factors influencing mechanical properties of clear aligners and research progress / 口腔医学

@#In recent years, clear aligner technology has been maturing and is rapidly gaining popularity in the orthodontic market for its aesthetic and removable properties. However, despite the background of its large-scale clinical application, mechanical properties of clear aligners need to be studied in depth. This paper reviews the factors influencing mechanical properties of clear aligners and the current status of research to provide evidence-based guidance for clinical application.

Response of masticatory muscles to treatment with orthodontic aligners: a preliminary prospective longitudinal study

ABSTRACT Introduction: The emergence of orthodontic aligners has provided an aesthetic and comfortable option for orthodontic treatment. However, the encapsulated design of the aligners can influence the masticatory muscles, and might compromise safe treatment. Objective: This preliminary longitudinal study aimed to investigate whether the use of orthodontic aligners affects the biting force and myoelectric activity of the superficial masseter and anterior temporal muscles. Methods: Ten subjects participated in the study and underwent treatment during an 8-month follow-up period. The root mean square (RMS), the median power frequency (MPF) of the surface electromyography (sEMG) signals, and the biting force (kgf) were recorded and normalized relative to the pretreatment condition. The data were analyzed by repeated-measure analysis of variance (ANOVA), with the significance level set at 5%. Results: Both the superficial masseter and the anterior temporal muscles presented an increase in sEMG signal activity during the treatment, with a marked increase in the latter compared to the former (p<0.05). Moreover, a significant decrease in bite force was evidenced (p<0.05). Conclusions: This preliminary study observed that the orthodontic aligners affected the muscle recruitment pattern of masticatory muscles, and reduced biting performance during the 8-month follow-up period.

RESUMO Introdução: O surgimento dos alinhadores ortodônticos tem proporcionado uma opção estética e confortável para o tratamento ortodôntico. No entanto, o design encapsulado dos alinhadores pode influenciar os músculos mastigatórios e comprometer a segurança do tratamento. Objetivo: Este estudo longitudinal preliminar teve como objetivo investigar se o uso de alinhadores ortodônticos afeta a força de mordida e a atividade mioelétrica dos músculos masseter superficial e temporal anterior. Métodos: Dez indivíduos participaram do estudo e foram submetidos a tratamento durante um período de acompanhamento de 8 meses. A raiz quadrada média (RMS), a frequência mediana de potência (FMP) dos sinais de superfície da eletromiografia (sEMG) e a força de mordida (kgf) foram registradas e normalizadas em relação à condição de pré-tratamento. Os dados foram analisados por análise de variância para medidas repetidas (ANOVA), com nível de significância estabelecido em 5%. Resultados: Tanto o masseter superficial quanto o temporal anterior apresentaram aumento da atividade do sinal sEMG durante o tratamento, com aumento acentuado desse último em comparação ao primeiro (p<0,05). Além disso, foi evidenciada uma diminuição significativa da força de mordida (p<0,05). Conclusões: Esse estudo preliminar observou que os alinhadores ortodônticos afetaram o padrão de recrutamento muscular dos músculos mastigatórios e reduziram o desempenho da mordida durante o período de acompanhamento de oito meses.

Morphology changes of maxillary molar distalization by clear aligner therapy / Cambios de la morfología en la distalización de molares maxilares mediante terapia con alineadores transparentes

SUMMARY: To evaluate the skeletal, dento-alveolar and soft tissue morphology changes after maxillary molar distalization by clear aligner therapy and identify the significant efficacy of molar distalization,18 patients in conformity with the inclusion criteria were selected. Pre- and post-treatment Cone Beam Computed Tomography (CBCT) were examined to measure the angular and linear parameters. All subjects were completed non-extraction clear aligner treatment by distalizing molars. A paired-t test and independent-samples t-test were performed to observe the difference between before and after treatment and the difference between the first molar and second molar respectively. P-values <0.05 were considered statistically significant. Predicted movement rate was calculated by the formula: (actual movement(mm)/planned movement(mm)) x100%. Most variables of pre- and post-treatment showed no statistical difference(P<0.05), excepting SNA angle (P<0.05) and Upper lip/E-line linear (P<0.01) due to incisor retraction. The first and second molar revealed a translation movement without significant tipping and vertical movement. Clear aligners provided a high predictability (83.44 %) of distalization the maxillary first molar, and 85.14 % of the maxillary second molar. Clear aligners can effectively achieve distal displacement of molars.

RESUMEN: Se seleccionaron 18 pacientes, de acuerdo con los criterios de inclusión, para evaluar los cambios en la morfología esquelética, dentoalveolar y de los tejidos blandos después de la distalización de los molares maxilares, mediante la terapia con alineadores transparentes e así identificar la significativa eficacia de la distalización de los molares. Se examinó a través de tomografía computarizada de haz cónico (CBCT) antes y después del tratamiento para medir los parámetros angulares y lineales. Todos los sujetos completaron el tratamiento con alineadores transparentes sin extracción mediante la distalización de los molares. Se realizó una prueba t pareada y una prueba t de muestras independientes para observar la diferencia entre antes y después del tratamiento y la diferencia entre el primer molar y el segundo molar, respectivamente. Los valores de p<0,05 se consideraron estadísticamente significativos. La tasa de movimiento prevista se calculó mediante la fórmula: (movimiento real (mm)/movimiento planificado (mm)) x 100 %. La mayoría de las variables de pre y postratamiento no mostraron diferencia estadística (P<0,05), excepto el ángulo SNA (P<0,05) y el labio superior/línea E lineal (P<0,01) debido a la retracción del incisivo. El primer y segundo molar revelaron un movimiento de traslación sin inclinación significativa y movimiento vertical. Los alineadores transparentes proporcionaron una alta previsibilidad (83,44 %) de la distalización del primer molar superior y del 85,14 % del segundo molar superior. Los alineadores transparentes pueden lograr efectivamente el desplazamiento distal de los molares.

Aligners: The Science of Clear Orthodontics

Since their inception, clear aligners have undergone multitude of advancements that aimed to make the orthodontic treatment less conspicuous. Used for moving teeth for alignment and creating healthy and beautiful smiles, like many other orthodontic appliances, clear aligners have proven to be a much more comfortable and esthetic alternative. The treatment success relies on clinicians’ knowledge and experience with the aligners, proper case selection, and the patients’ adherence to the treatment protocols. The area of exploration of this review is limited to providing an overview of the clear aligner treatment including benefits and limitations, principles and biomechanics of clear aligner treatment, materials used, methods of fabrication, and wear time. Umpteen manufacturers have emerged accounting for the increased demand by patients seeking orthodontic treatment, with the number increasing every year. It is outside the purview of this article to elucidate and compare the array of clear aligner systems available today.

Maxillary expansion efficiency with clear aligner and its possible influencing factors / 中华口腔医学杂志

Objective@#To evaluate the efficiency of maxillary expansion with clear aligners and to analyze the possible influence factors.@*Methods@#Thiry-one clear aligner cases (Invisalign) with maxillary expansion were enrolled in this study. The three-dimensional (3D) digital models of pre-treatment, planned in Clincheck software and post-treatment were collected. Upper dental arch width, buccal inclination of posterior teeth, and the expansion efficiency (expansion acquired/expansion planned) were measured and calculated. The impact of factors such as planned buccal inclination, planned expansion amount, attachment, and the mode of expansion on the expansion efficiency were analyzed.@*Results@#The increases of upper arch width in canine, 1st and 2nd premolar, 1st and 2nd molar were (2.0±1.3), (2.8±1.5), (3.0±1.4), (1.8±1.0) and 0.5 (0.1, 1.1) mm, with their efficiency of 68%, 70%, 68%, 55% and 29%, respectively. The posterior teeth showed significantly more buccal inclination than the planned position (P<0.05). However, the most buccally inclined tooth detected in 1st molars was only 3.1°±3.9°. When the planned inter-molar width increase was less than 2 mm (n=15), the expansion efficiency of premolars was higher compared with those cases with the planned inter-molar width increase more than 2 mm (n=16, P<0.05). The planned buccal inclination, attachments, and the expansion mode had no significant effect on the expansion efficiency (P>0.05).@*Conclusions@#The expansion of maxillary arch with clear aligners was achieved by the buccal movement of the posterior teeth with limited buccal inclination. The efficiency of expansion declines from 1st premolars to second molars. The planned inter-molar width had a significant influence on the efficiency of premolar expansion.

Advantages and disadvantages of clear aligner treatment in orthodontics / 中华口腔医学杂志

As biomaterial and biomechanics have been growing and developing rapidly, the indication of clear aligner treatment has been broadened from simple crowding or spacing to moderate malocclusion including either extraction or non-extraction cases. Considering the advantage of its prospective three-dimensional digital planning as well as the disadvantage of limited capability of three-dimensional tooth movement control, orthodontists have to be fully aware of the characteristics and weakness of this appliance so as to choose proper indications and achieve good treatment results. Meanwhile, orthodontists also have to play an important role in modifying the three-dimensional digital plan with pouring in their clinical experience on treating cases and estimating different tooth movement efficiency in various kinds of malocclusions.

Extraction cases using clear aligners / 中华口腔医学杂志

Clear aligner treatment achieves patients' precise tooth movements through utilizing patients' digital dental models and tooth movement planning by orthodontists. Originated from the rudimentary form in 1940's, clear aligner has undergone many innovations and developments. A strict selection of extraction patients for clear aligner treatments is a prerequisite of good treatment outcomes. Orthodontists should first master the unique features of aligner biomechanics and mechanisms. For extraction patients treated with clear aligners, orthodontists should focus on anchorage control, torque control and vertical control, and strictly monitoring treatment progressions, as to achieve satisfactory treatment outcomes. With the development of dental materials and techniques, we believe that clear aligner treatment will be a mainstay of future orthodontic treatments.

Invisible orthodontics: clear aligners and customized lingual appliances / 中华口腔医学杂志

In recent years, invisible orthodontics has been one of the concerns of both orthodontists and patients. As two types of invisible orthodontics, clear aligners fit for cases that have high demand for living quality, need distalization of molars or intrusion of incisors, suffer from severe periodontitis, or that have non-abundant time for visits. While customized lingual appliances fit for cases that have high demand for aesthetics, have deep overbite or complex malocclusion, need maxillary expansion or retraction of incisors, or that have low compliance and good economic conditions. Based on aspects of clinical application, this article presents the characteristics of these two types of invisible orthodontics, in order to provide reference for individualized options according to different situations.

A oportunidade de tratamentos híbridos na era da ortodontia digital / Hybrid treatment option in the digital orthodontics era

Tratamentos híbridos associados à Ortodontia Digital são uma eficiente opção para tratamentos de casos clínicos simples e complexos. O propósito desse trabalho é atualizar os ortodontistas sobre a realidade e oportunidade de realizar tratamentos combinados, assim como usufruir das últimas tecnologias da odontologia digital para modernizar sua prática ortodôntica e consultório.(AU)

Hybrid treatments associated to Digital Orthodontics are an efficient treatment option to moderate and complex clinical cases. The aim of this paper is to offer an update to orthodontists about the reality and opportunity to perform combined treatments and to present the latest dental digital technologies for their practice as well.(AU)

The combined use of computer-guided, minimally invasive, flapless corticotomy and clear aligners as a novel approach to moderate crowding: A case report / 대한치과교정학회지

The aim of this case report was to describe an innovative orthodontic treatment method that combined surgical and orthodontic techniques. The novel method was used to achieve a positive result in a case of moderate crowding by employing a computer-guided piezocision procedure followed by the use of clear aligners. A 23-year-old woman had a malocclusion with moderate crowding. Her periodontal indices, oral health-related quality of life (OHRQoL), and treatment time were evaluated. The treatment included interproximal corticotomy cuts extending through the entire thickness of the cortical layer, without a full-thickness flap reflection. This was achieved with a three-dimensionally printed surgical guide using computer-aided design and computer-aided manufacturing. Orthodontic force was applied to the teeth immediately after surgery by using clear appliances for better control of tooth movement. The total treatment time was 8 months. The periodontal indices improved after crowding correction, but the oral health impact profile showed a slight deterioration of OHRQoL during the 3 days following surgery. At the 2-year retention follow-up, the stability of treatment was excellent. The reduction in surgical time and patient discomfort, increased periodontal safety and patient acceptability, and accurate control of orthodontic movement without the risk of losing anchorage may encourage the use of this combined technique in appropriate cases.

Integrated three-dimensional digital assessment of accuracy of anterior tooth movement using clear aligners / 대한치과교정학회지

OBJECTIVE: To assess the accuracy of anterior tooth movement using clear aligners in integrated three-dimensional digital models. METHODS: Cone-beam computed tomography was performed before and after treatment with clear aligners in 32 patients. Plaster casts were laser-scanned for virtual setup and aligner fabrication. Differences in predicted and achieved root and crown positions of anterior teeth were compared on superimposed maxillofacial digital images and virtual models and analyzed by Student's t-test. RESULTS: The mean discrepancies in maxillary and mandibular crown positions were 0.376 +/- 0.041 mm and 0.398 +/- 0.037 mm, respectively. Maxillary and mandibular root positions differed by 2.062 +/- 0.128 mm and 1.941 +/- 0.154 mm, respectively. CONCLUSIONS: Crowns but not roots of anterior teeth can be moved to designated positions using clear aligners, because these appliances cause tooth movement by tilting motion.