Evaluation of maxillary canine and molar movement during the first phase of extraction space closure: a multilevel analysis.

OBJECTIVE: This study was designed to analyze and compare the cusp and apex movements of the maxillary canines and first molars during canine retraction in the first step of extraction space closure, and to evaluate if these teeth follow a curvilinear (acceleration and/or deceleration) movement rate. MATERIAL AND METHODS: Twenty-five patients (23.3 ± 5.1 years of age) were enrolled. The retraction of the maxillary canines was accomplished using nickel-titanium closed coil springs (100gf) on 0.020-in stainless steel archwire. Oblique cephalograms were traced and superimposed on the anatomic best fit of the maxilla (before the retraction [T0], and after one month [T1], three [T3], five [T5] and seven [T7] months). Statistics was based in a normally distributed data. Multilevel procedures were used to derive polynomials for each of the measurements. Student's t-test and one-way repeated measures ANOVA were conducted. The level of significance of 5% was adopted. RESULTS: Canine cusps and apexes did not follow a quadratic curve regarding horizontal movement (neither accelerate nor decelerate). Canine and molar cusps showed more horizontal movement than apexes (4.80 mm vs. 2.78 mm, and 2.64 mm vs. 2.17 mm, respectively). CONCLUSIONS: Canine did not accelerate or decelerate overtime horizontally; the cusps and apexes of the canines and molars showed more horizontal movement and larger rate at the beginning of canine retraction, followed by significantly smaller and constant movement rate after the first month.

Evaluation of maxillary canine and molar movement during the first phase of extraction space closure: a multilevel analysis

ABSTRACT Objective: This study was designed to analyze and compare the cusp and apex movements of the maxillary canines and first molars during canine retraction in the first step of extraction space closure, and to evaluate if these teeth follow a curvilinear (acceleration and/or deceleration) movement rate. Material and Methods: Twenty-five patients (23.3 ± 5.1 years of age) were enrolled. The retraction of the maxillary canines was accomplished using nickel-titanium closed coil springs (100gf) on 0.020-in stainless steel archwire. Oblique cephalograms were traced and superimposed on the anatomic best fit of the maxilla (before the retraction [T0], and after one month [T1], three [T3], five [T5] and seven [T7] months). Statistics was based in a normally distributed data. Multilevel procedures were used to derive polynomials for each of the measurements. Student's t-test and one-way repeated measures ANOVA were conducted. The level of significance of 5% was adopted. Results: Canine cusps and apexes did not follow a quadratic curve regarding horizontal movement (neither accelerate nor decelerate). Canine and molar cusps showed more horizontal movement than apexes (4.80 mm vs. 2.78 mm, and 2.64 mm vs. 2.17 mm, respectively). Conclusions: Canine did not accelerate or decelerate overtime horizontally; the cusps and apexes of the canines and molars showed more horizontal movement and larger rate at the beginning of canine retraction, followed by significantly smaller and constant movement rate after the first month.

RESUMO Objetivo: O objetivo deste estudo foi analisar a movimentação das cúspides e dos ápices de caninos e primeiros molares superiores durante a retração de caninos na primeira fase do fechamento do espaço pós-extração, e avaliar se esses dentes apresentam mudança na taxa de movimentação (aceleração e/ou desaceleração). Material e Métodos: Vinte e cinco pacientes (idade = 23,3 ± 5,1 anos) foram incluídos. A retração dos caninos superiores foi realizada com molas helicoidais fechadas de níquel-titânio (100gf) em arco 0,020" de aço inoxidável. Foram feitos traçados cefalométricos de telerradiografias oblíquas e sobrepostos ao melhor ajuste anatômico da maxila (antes da retração [T0]; após um mês [T1], três meses [T3], cinco meses [T5] e sete meses [T7]). A estatística foi baseada em dados com distribuição normal. Procedimentos multiníveis foram usados para derivar polinômios para cada uma das medidas. Teste t de Student e ANOVA de uma via para medidas repetidas foram realizados, adotando-se um nível de significância de 5%. Resultados: As cúspides e os ápices dos caninos não seguiram uma curva quadrática em relação ao movimento horizontal (sem aceleração ou desaceleração). As cúspides dos caninos e molares apresentaram mais movimento horizontal do que os ápices (4,80 mm vs. 2,78 mm e 2,64 mm vs. 2,17mm, respectivamente). Conclusões: A movimentação horizontal dos caninos não acelerou ou desacelerou ao longo do tempo; as cúspides e os ápices dos caninos e molares apresentaram maior movimento horizontal e maior taxa de movimentação no início da retração dos caninos, seguida por uma taxa de movimentação significativamente menor e constante após o primeiro mês.

Speech performance in adult patients undergoing Invisalign treatment.

OBJECTIVES: To assess speech performance of adult patients undergoing orthodontic treatment with Invisalign. MATERIALS AND METHODS: Twenty-four adult patients with Invisalign (Invisalign group: 6 men, 18 women; average age; 34.88 years) and 20 adult patients with fixed labial appliances (fixed group: 5 men, 15 women; average age; 38.85 years) were evaluated. Speech was recorded immediately before delivery of the first set of clear aligners or bonding of labial appliances (T0), immediately after delivery or bonding (T1), and 2 months after delivery or bonding (T2). Speech was evaluated via a combination of three auditory analyses: (1) objective acoustic analysis through digital sonography, (2) semiobjective assessment by six speech and language pathologists, and (3) subjective assessment patient questionnaire. RESULTS: The objective acoustic analysis showed a statistically significant difference over time from T0 to T1, T1 to T2, and T0 to T2 for Invisalign patients. The semiobjective analysis revealed a significant speech alteration from T0 to T1 and T1 to T2 for both groups, and from T0 to T2 in the Invisalign group. The subjective analysis showed a significant difference between means of Invisalign and fixed group patient perception at both T1 and T2. CONCLUSIONS: Invisalign treatment significantly affected speech, and although patients experience some level of adaptation, speech does not return to normal after 2 months of treatment.

Class II malocclusion correction with Invisalign: Is it possible?

INTRODUCTION: This research aimed to determine whether Class II malocclusion can be treated with clear aligners after completing treatment with the initial set of aligners. METHODS: A sample of 80 adult patients were divided into Group 1 with Class I molar malocclusions (n = 40 [11 men and 29 women]; 38.70 ± 15.90 years) and Group 2 with Class II molar malocclusions (n = 40 [11 men and 29 women]; 35.25 ± 15.21 years). All patients had finished treatment with the initial set of Invisalign aligners (Align Technology, Santa Jose, Calif) without known centric occlusion-centric relation discrepancies, issues of compliance, or overcorrection. The 7 measurements using the American Board of Orthodontics (ABO) Model Grading System and millimetric measurements for anteroposterior (AP) and vertical dimensions were assessed and compared between the 2 groups at pretreatment, posttreatment ClinCheck (Align Technology) prediction, and posttreatment. RESULTS: No improvements were observed in the AP correction. The amount of AP correction in patients with Class II malocclusion was 6.8% of the predicted amount. The amount of overbite correction achieved was 28.8% and 38.9% of the predicted amounts in patients with Class I and Class II malocclusion, respectively. Significant improvements in alignment and interproximal contact scores were observed, with only slight improvements in total ABO scores. An increase in mean occlusal contacts score was observed after treatment. No patient with Class II malocclusions would meet the ABO standards after Invisalign treatment. CONCLUSIONS: The Invisalign system successfully achieves certain tooth movements but fails to achieve other movements predictably. No significant Class II correction or overjet reduction was observed with elastics for an average of 7-month duration in the adult population. Additional refinements may be necessary to address problems created during treatment, as evidenced by a posterior open bite incidence.

Esthetic perception of clear aligner therapy attachments using eye-tracking technology.

INTRODUCTION: The purpose of this research was to assess and compare esthetic perceptions of clear aligner therapy with attachments and esthetic brackets by measuring differences in eye fixations using eye-tracking technology. METHODS: The sample involved 250 adult subjects. The subjects gave verbal consent, then viewed photographs showing 4 variations of orthodontic appliances: clear aligner control with minimal attachments, clear aligner with anterior and posterior attachments, esthetic brackets, and clear aligner with posterior attachments. Images were displayed for 6 seconds each on a computer monitor. Location and time to first fixation, total fixation duration, and total visit count and duration for each type of appliance were measured. Subjects were then asked to complete an online survey. RESULTS: Participants spent the least amount of time looking at the photograph of the control, followed by those of the ceramic brackets, posterior attachments, and anterior and/or posterior attachments. The anterior and/or posterior image had the least number of visits but garnered the longest visit duration (1.32 visits averaging 0.74 seconds per visit). This was followed by the images of the posterior attachments (1.40 visits, 0.70 seconds per visit), ceramic brackets (1.43 visits, 0.65 seconds per visit), and minimal attachments control (1.45 visits, 0.61 seconds per visit). The hierarchy of most preferred appliances across all 250 respondents was as follows: minimal attachments control, ceramic brackets, posterior attachments, and anterior and/or posterior attachments. Overall, 88.4% of subjects would compromise appliance esthetics during treatment for a better outcome (n = 221). CONCLUSIONS: Eye-tracking data show that time to the first fixation was negatively correlated with its survey ranking and that an increase in attachments led to an increase in total fixation duration. There is a general desire for clear aligners without attachments and ceramic brackets over clear aligners with multiple attachments. Survey data suggest that although respondents viewed appliance esthetics as highly important, nearly all would compromise appliance esthetics during treatment if it resulted in a better outcome.

Which one closes extraction spaces faster: en masse retraction or two-step retraction? A randomized prospective clinical trial.

OBJECTIVES: To compare the time to close extraction spaces between en masse (ER) and two-step retraction (TSR). MATERIALS AND METHODS: Forty-eight patients with bimaxillary protrusion underwent treatment with extraction of four first premolars. All patients were randomly allocated to one of two groups: ER (n = 24) or TSR (n = 24). The main outcome was the time required to close spaces between ER and TSR; the closing time of spaces between females and males was a secondary outcome. The size of premolars was measured on the models and data were collected on clinical records at the following times: retraction start date (T1) and space closure completion date (T2). The total time to close the extraction spaces was calculated for each extracted premolar (T1 to T2). The Kaplan Meier method and the Log-Rank test were used to compare the groups. RESULTS: The time to close extraction spaces showed significant differences between the ER and TSR groups. While ER took between 12.1 and 13.8 months, TSR took between 24.7 and 26.8 months. The TSR group showed a significant difference between sexes; male patients took 5.5 months longer than female patients for the extraction spaces to close. CONCLUSIONS: TSR takes between 1.8 and 2.2 times longer than ER to close the extraction spaces and it took longer in males than females.

Comparison of anterior retraction and anchorage control between en masse retraction and two-step retraction: A randomized prospective clinical trial.

OBJECTIVES: The purpose of this two-arm parallel trial was to compare en masse (ER) and two-step retraction (TSR) during space closure. MATERIALS AND METHODS: Forty-eight adult patients with bimaxillary protrusion who were planned for treatment with extraction of four first premolars were enrolled. All patients were randomly allocated in a 1:1 ratio to either the ER (n = 24) group or the TSR (n = 24) group. The main outcome was the amount of posterior anchorage loss in the molars and the retraction of the incisors between ER and TSR; the difference in incisor and molar inclination was a secondary outcome. Lateral cephalometric radiographs and oblique cephalometric radiographs at 45° were taken before retraction (T1) and after space closure (T2). Cephalograms were digitized and superimposed on the anatomic best fit of the maxilla and mandible by one operator who was blinded to the treatment group. RESULTS: Neither incisor nor molar crown movements showed any significant differences between the ER and TSR. There were no significant differences in the tipping of incisors and molars between the two groups. CONCLUSIONS: No significant differences existed in the amount of retraction of incisors and anchorage loss of molars between ER and TSR. Changes in incisor and molar tipping were similar, with the crowns showing more movement than the apex.

Efeito da contaminação por saliva na resistência adesiva de braquetes cerâmicos utilizando uma resina ortodôntica hidrofílica / Saliva contamination effect on shear bond strength of ceramic brackets with an orthodontic hydrophilic resin

Introdução: Alguns fatores, como a presença de saliva, são capazes de influenciar a adesão do braquete ao dente durante o procedimento de colagem e podem causar falha da resistência adesiva. Objetivo: O objetivo deste estudo foi avaliar a resistência ao cisalhamento de braquetes cerâmicos ortodônticos colados com Transbond XT e Transbond Plus Color Change em esmalte de dentes bovinos, contaminado e não contaminado por saliva, além de analisar o local da falha adesiva. Material e método: Sessenta incisivos bovinos foram divididos aleatoriamente em quatro grupos (n=15), de acordo com o material de colagem e a presença de contaminação: Grupo 1 (G1): colagem com Transbond XT na ausência de contaminação; Grupo 2 (G2): colagem com Self Etching Pimer e Transbond Color Change na ausência de contaminação; Grupo 3 (G3): colagem com Transbond XT na presença de contaminação, e Grupo 4 (G4): colagem com Self Etching Primer e Transbond Color Change na presença de contaminação. Resultado: O teste não paramétrico de Kruskal-Wallis mostrou que G1 diferiu estatisticamente (p<0,05) de G2 e G3. Não houve diferença estatística significativa entre os demais grupos. O índice de adesivo remanescente (IAR) variou entre 2 e 3 no G1 e entre 0 e 1 nos outros grupos. Conclusão: A contaminação por saliva diminui a resistência adesiva ao cisalhamento de braquetes cerâmicos colados com a resina hidrofóbica Transbond XT convencional. Por outro lado, a utilização da resina hidrofílica Transbond Plus Color Change associada ao Self Etching Primer, em ambiente contaminado por saliva, confere resistência adesiva adequada para o seu uso clínico.

Introduction: Some fator, such as the presence of saliva, are able to influence the adhesion of the bracket to the tooth enamel during the orthodontic bonding procedure and may cause the adhesive failure. Objective: The aim of this study was to evaluate the shear strength of orthodontic ceramic brackets bonded with Transbond XT and Transbond Plus Color Change to bovine teeth, under saliva contamination and the adhesive failure mode. Material and method: Sixty bovine permanent incisors were randomly divided into 4 groups (n=15) according to bonding material and saliva contamination: Group 1 (G1) bonded with Transbond XT with no saliva contamination; Group 2 (G2) bonded with Self Etching Primer and Transbond Plus Color Change with no saliva contamination; Group 3 (G3) bonded with Transbond XT with saliva contamination and Group 4 (G4) bonded with Transbond Plus Color Change with saliva contamination. Result: The Kruskal-Wallis non-parametric test (p<0,05) was used and showed that G1 differed statistically from G2 and G3. There was no statistical difference between the other groups. The adhesive remnant index (ARI) ranged between 2 and 3 in G1 and between 0 and 1 score in the other groups. Conclusion: Saliva contamination decreases the shear bond strength of ceramic brackets bonded with conventional Transbond XT hydrophobic resin. On the other hand, the Transbond Plus Color Change hydrophilic resin associated with a Self Etching Primer, under saliva contamination, provide a sufficient shear bond strength, suitable for their clinical use.

Histological evaluation of the effects of corticotomy on induced orthodontic movement in rats / Avaliação histológica dos efeitos da corticotomia no movimento ortodôntico induzido em ratos

Introduction: Alveolar corticotomy is a surgical procedure used to increase the velocity of tooth movement. Objective: Identify histological evidence of the effect of corticotomy on orthodontic movement in rats. Material and method: Forty-five Wistar rats (Rattusnorvegicus Albinus) were equally divided into three groups: Control Group (CG) - no tooth movement or corticotomy; Movement Group (MG) - tooth orthodontic movement only; and Corticotomy and Movement Group (CMG) - tooth orthodontic movement surgically assisted by corticotomy. In the CMG, surgical procedures consisted in an incision in the palatal, reaching from the mesial to the distal regions of the maxillary right first molar. Tooth movement in the MG and CMG was applied with coil spring force of 40 gF from the maxillary right first molar to the maxillary right incisor. The rats were sacrificed at days 1, 3, and 7, and histological sections were performed to evaluate the counting of osteoblasts and osteoclasts throughout the areas of tension and pressure. Result: Histological analysis showed that the CMG presented better cell response to bone neoformation compared with that of the other groups. Greater proliferation of osteoclasts was observed in areas of pressure on day 3, resulting in increased reabsorption, whereas greater proliferation of osteoblasts was observed in areas of tension on day 1, indicating increased bone formation. Conclusion: Differences between the treated groups occurred only in the initial period of tooth movement. Therefore, the changes caused by corticotomy are not significant in orthodontic movement to justify this invasive procedure.

Introdução: A corticotomia alveolar é um procedimento cirúrgico utilizado para aumentar a velocidade do movimento dentário. Objetivo: Identificar evidências histológicas do efeito da corticotomia no movimento ortodôntico no rato. Material e método: Quarenta e cinco ratos Wistar (Rattusnorvegicus Albinus) foram igualmente divididos em três grupos: Grupo de Controle (GC) - sem movimento dentário ou corticotomia; Grupo de movimento (GM) - apenas movimento ortodôntico do dente; e Corticotomia e Movimento Grupo (GCM) - movimento ortodôntico dentário cirurgicamente assistido por corticotomia. Os procedimentos cirúrgicos de GCM consistiram de uma incisão no palato, da mesial a distal do primeiro molar superior direito. O movimento do dente no GM e GCM foi aplicado com uma força da mola helicoidal de 40 gF do primeiro molar superior direito para o incisivo superior direito. Os ratos foram sacrificados no 1º, 3º e 7º dia e, após este período, foram realizadas seções histológicas para avaliar a contagem de osteoblastos e osteoclastos nas áreas de tensão e pressão. Resultado: A análise histológica mostrou que o GCM apresentou melhor resposta celular na neoformação óssea quando comparado aos outros grupos. Em áreas de pressão, no 3º dia, houve uma maior proliferação de osteoclastos, resultando em maior reabsorção. Em áreas de tensão, no 1º dia, houve uma maior proliferação de osteoblastos, indicando aumento da formação óssea. Conclusão: A diferença entre os grupos tratados ocorreu apenas no período inicial do movimento. Portanto, as alterações causadas pela corticotomia não são significativas no movimento ortodôntico para justificar o procedimento invasivo.