Study on quantitative analysis of bracket-induced nonlinear response of labio-cheek soft tissue during the orthodontic process / 生物医学工程学杂志

In the orthodontics process, intervention and sliding of an orthodontic bracket during the orthodontic process can arise large response of the labio-cheek soft tissue. Soft tissue damage and ulcers frequently happen at the early stage of orthodontic treatment. In the field of orthodontic medicine, qualitative analysis is always carried out through statistics of clinical cases, while quantitative explanation of bio-mechanical mechanism is lacking. For this purpose, finite element analysis of a three-dimensional labio-cheek-bracket-tooth model is conducted to quantify the bracket-induced mechanical response of the labio-cheek soft tissue, which involves complex coupling of contact nonlinearity, material nonlinearity and geometric nonlinearity. Firstly, based on the biological composition characteristics of labio-cheek, a second-order Ogden model is optimally selected to describe the adipose-like material of the labio-cheek soft tissue. Secondly, according to the characteristics of oral activity, a two-stage simulation model of bracket intervention and orthogonal sliding is established, and the key contact parameters are optimally set. Finally, the two-level analysis method of overall model and submodel is used to achieve efficient solution of high-precision strains in submodels based on the displacement boundary obtained from the overall model calculation. Calculation results with four typical tooth morphologies during orthodontic treatment show that: ① the maximum strain of soft tissue is distributed along the sharp edges of the bracket, consistent with the clinically observed profile of soft tissue deformation; ② the maximum strain of soft tissue is reduced as the teeth align, consistent with the clinical manifestation of common damage and ulcers at the beginning of orthodontic treatment and reduced patient discomfort at the end of treatment. The method in this paper can provide reference for relevant quantitative analysis studies in the field of orthodontic medical treatment at home and abroad, and further benefit to the product development analysis of new orthodontic devices.

Application of 3D printed personalized breast bracket in IMRT for breast cancer / 中华放射肿瘤学杂志

Objective:By comparing the positioning errors caused by 3D printed personalized breast bracket and common headrest in intensity-modulated radiation therapy (IMRT), the fixation effect of 3D printed personalized breast bracket in IMRT was analyzed.Methods:Thirty-two breast cancer patients from January to July 2021 were randomly divided into a the 3D printed breast bracket group and common headrest group. All patients in two groups were kept in supine position, head tilted to the healthy side, the affected hand held the grip bar on the same side of the horizontal bar, the healthy hand held the opposite side of the vertical bar, and the chest and mandible were fixed with thermoplastic film. CBCT scan was performed weekly, and gray level registration was carried out according to the three registration regions of interest: breast or chest wall field, supraclavicular and inferior field, and axillary field. The positioning errors in the left and right, head and foot, abdomen and back directions were analyzed between two groups.Results:In the 3D printed breast bracket group, the positioning errors of breast or chest wall field, supraclavicular and inferior field and axillary field in the left and right, head and foot, abdomen and back directions were (1.75±1.26), (1.77±1.11) and (1.70±1.08) mm, (1.75±1.25), (1.72±1.09) and (1.70±1.05) mm,(1.86±1.34), (2.14±2.13) and (1.66±1.19) mm, respectively.In the common headrest group, the positioning errors of breast or chest wall field, supraclavicular and inferior field and axillary field in the left and right, the head and feet, the abdomen and back directions were (2.54±1.84), (2.73±3.62) and (2.18±2.45) mm, (3.25±2.02), (3.52±2.26) and (2.62±2.83) mm, (3.25±2.05), (4.44±2.90) and (3.10±3.18) mm, respectively.The positioning errors significantly differed between two groups (all P<0.05). Conclusions:The positioning error of 3D printed personalized breast bracket fixation is less than that of common headrest fixation. The positioning consistency of 3D printed personalized breast bracket in the three target areas of breast or chest wall field, supraclavicular and inferior field and axillary field is better than that of common headrest.

Comparative evaluation of three methods of adhesive remnant removal after orthodontic bracket debonding

ABSTRACT Objective: This study aimed to assess the effects of three methods of adhesive remnant removal (carbide bur and low speed handpiece, carbide bur and high speed handpiece, and zircon-rich glass fiber reinforced composite bur), after orthodontic bracket debonding, on tooth color and enamel surface roughness. Methods: Ninety sound premolar teeth were selected. The baseline tooth color was assessed using Vita spectrophotometer. The teeth were subjected to bracket bonding processes and then randomly divided into three equal groups. In each group, composite remnant was removed by one of the three methods of adhesive removal, and the teeth were then subjected to color assessment again. To measure the surface roughness, a scanning electron microscope (SEM) with x400 magnification was used. Results: ANOVA showed that the effect of the three methods of adhesive remnant removal on ∆L, ∆b and ∆E was statistically significant (p=0.01), but without significant effect on ∆a. Comparison of the means showed that composite bur and high speed carbide bur yielded the highest ∆E (p=0.05), and had a significant difference when compared to carbide bur and low speed handpiece. The highest ∆L and ∆b values belonged to samples approached with composite bur and carbide bur with high speed handpiece, respectively. SEM analysis showed that the composite bur created a very smooth surface, compared to the other two methods. Conclusion: Zircon-rich glass fiber reinforced composite created the smoothest enamel surface and highest color change, when compared to the other two methods.

RESUMO Objetivo: O presente estudo teve como objetivo avaliar os efeitos de três métodos de remoção de adesivo remanescente (broca carbide e peça de mão em baixa rotação, broca carbide e peça de mão em alta rotação, e broca de compósito reforçado com fibra de vidro rica em zircônia), após a descolagem de braquetes ortodônticos, sobre a cor dos dentes e rugosidade superficial do esmalte. Métodos: Noventa pré-molares hígidos foram selecionados. A cor inicial dos dentes foi avaliada usando um espectrofotômetro Vita. Os dentes foram submetidos à etapa de colagem dos braquetes e, então, divididos aleatoriamente em três grupos. Em cada grupo, o adesivo remanescente foi removido usando um dos três métodos de remoção, e os dentes foram novamente submetidos à avaliação de cor. Para medir a rugosidade superficial dos dentes, foi usado um microscópio eletrônico de varredura (MEV) com aumento de 400x. Resultados: A ANOVA mostrou que os três métodos de remoção do adesivo remanescente tiveram efeito estatisticamente significativo (p=0,01) em ∆L, ∆b e ∆E, mas sem efeito significativo em ∆a. A comparação das médias mostrou que a broca de compósito e a broca carbide em alta rotação produziram o maior ∆E (p=0,05) e tiveram uma diferença significativa quando comparadas com a broca carbide e a peça de mão em baixa rotação. Os maiores valores de ∆L e ∆b foram encontrados, respectivamente, nos grupos com broca de compósito e broca carbide usando peça de mão em alta rotação. A análise MEV mostrou que o uso da broca de compósito resultou em uma superfície muito lisa, em comparação com os outros dois métodos. Conclusão: Em comparação aos outros métodos, a broca de compósito reforçado com fibra de vidro rica em zircônia criou a superfície de esmalte mais lisa e resultou em uma maior mudança de cor.

Effectiveness of different orthodontic adhesives and a universal bonding resin on the bond strength of brackets to different ceramics / Eficácia de diferentes adesivos ortodônticos e uma resina de ligação universal na resistência adesiva de bráquetes à diferentes cerâmicas

Objective: The aim of this study was to evaluate the effectiveness of different adhesives on the shear bond strength (SBS) of brackets bonded to different ceramic materials. Material and Methods: Fifty disk-shaped specimens were produced from lithium disilicate (IPS e.max CAD) and monolithic zirconia (Cercon) materials. Each specimen was polished with a three-step diamond polishing system. The polished ceramic surfaces were conditioned with universal bonding resin (Assure Plus) without pre-treatment, except for two specimens. Central brackets were bonded onto different ceramic specimens with different adhesives as follows: group 1: conventional adhesive onto the lithium disilicate; group 2: one-step adhesive onto the lithium disilicate; group 3: conventional adhesive onto the monolithic zirconia; group 4: one-step adhesive onto the monolithic zirconia. After thermal cycling, the specimens were subjected to the SBS test. The adhesive remnant index (ARI) scores were also recorded to evaluate bond failure type. Kruskal­Wallis and Mann-Whitney U tests were used for statistical analysis. Results: There were statistically significant differences among the SBS values (p˂0.05). The monolithic zirconia group with universal bonding resin and conventional orthodontic adhesive demonstrated the highest SBS value (6.34 MPa) and ARI scores. The lithium disilicate group showed the lowest SBS value (2.17 MPa) with the same protocol. No adhesive remained on the lithium disilicate specimens. Conclusion: One-step adhesive and universal bonding resin combination should not be considered as an alternative for lithium disilicate and monolithic zirconia restorations. Conventional adhesive and universal bonding resin application can be effective on non-pretreated ceramic surfaces during orthodontic bonding (AU)

Objetivo: o objetivo deste estudo foi avaliar a eficácia de diferentes adesivos na resistência ao cisalhamento (SBS) de bráquetes colados a diferentes materiais cerâmicos. Material e métodos: Cinquenta espécimes em forma de disco foram produzidos a partir de materiais de dissilicato de lítio (IPS e.max CAD) e zircônia monolítica (Cercon). Cada amostra foi polida com um sistema de polimento de diamante de três passos. As superfícies cerâmicas polidas foram condicionadas com resina de ligação universal (Assure Plus) sem pré-tratamento, exceto para dois corpos-de-prova. Bráquetes centrais foram colados em diferentes corpos de prova cerâmicos com diferentes adesivos da seguinte forma: grupo 1: adesivo convencional sobre dissilicato de lítio; grupo 2: adesivo de uma etapa sobre o dissilicato de lítio; grupo 3: adesivo convencional sobre zircônia monolítica; grupo 4: adesivo de uma etapa sobre a zircônia monolítica. Após a ciclagem térmica, os corpos-de-prova foram submetidos ao teste SBS. Os escores do índice de remanescente adesivo (ARI) também foram registrados para avaliar o tipo de falha de adesão. Os testes U de Kruskal-Wallis e Mann-Whitney foram usados para análise estatística. Resultados: Houve diferenças estatisticamente significativas entre os valores de SBS (p˂0,05). O grupo de zircônia monolítica com resina de colagem universal e adesivo ortodôntico convencional demonstrou o maior valor de SBS (6,34 MPa) e escores de ARI. O grupo de dissilicato de lítio apresentou o menor valor de SBS (2,17 MPa) com o mesmo protocolo. Nenhum adesivo permaneceu nas amostras de dissilicato de lítio. Conclusão: A combinação de adesivo de uma etapa e resina de ligação universal não deve ser considerada como uma alternativa para restaurações de dissilicato de lítio e zircônia monolítica. A aplicação de adesivo convencional e resina de colagem universal podem ser eficazes em superfícies de cerâmica não pré-tratadas durante a colagem ortodôntica (AU)

Application of different posture fixation methods in radiotherapy of breast cancer / 中华放射医学与防护杂志

Objective:To study the inter-fraction setup errors, intra-fraction movement of patients and its influence on dosimetry, position repeatability of the supraclavicular area, and the plastic stability of the vacuum cushion and styrofoam when one of the three fixation method are applied in the clinical radiotherapy of breast cancer. The three fixation method include acuum negative pressure pad (VP), acuum negative pressure pad combined with a breast bracket (VB), and polyurethane styrofoam combined with a breast bracket (PB).Methods:A total of 96 breast cancer patients who received radiotherapy at Jiangsu Cancer Hospital during 2019-2021 were collected prospectively for study. They were randomly divided into three groups (VP, VB, and PB). Cone-Beam CT and a planning system were used to obtain inter-fraction setup errors, intra-fraction movement of patients and its influence on dosimetry, position repeatability of supraclavicular area, and the plastic stability of vacuum pad and polyurethane tyrofoam.Results:In the left-right (LR) direction, there were no statistical differences in the inter-fraction setup errors among the three groups. In the superior-inferior (SI) direction, inter-fraction setup errors of the PB group were smaller than those of the VB group (3.02 ± 2.04, 3.65 ± 2.64, t=2.35, P=0.031). In the anterior-posterior (AP) direction, the inter-fraction setup errors of both the VB and PB groups were smaller than those of the VP group (3.36 ± 2.93, 3.14 ± 0.98, 4.03 ± 2.55, t=2.29, 3.11, P< 0.05). In the AP direction, the intra-fraction movement of patients of the VP and PB groups were less than that of the VB group (1.31 ± 0.95, 1.24 ± 0.89, 1.88 ± 1.33, t=-2.04, -2.31, P< 0.05). Moreover, the intra-fraction movement of patients had no statistical effect on the dosimetric distribution ( P> 0.05), and the breast bracket did not improve the position repeatability of the supraclavicular region ( P>0.05). In addition, the plastic stability of polyurethane styrofoam was significantly better than that of the acuum negative pressure pad ( t=2.43-5.63, P< 0.05). Conclusions:The inter-fraction setup errors and intra-fraction movement of patients with breast cancer can be reduced by using PB. Compared to an acuum negative pressure pad, polyurethane styrofoam can keep plastic stability throughout the treatment of the patients.

Analysis of setup errors of vacuum pad combined with breast bracket fixation in linear accelerator intensity-modulated radiotherapy for breast cancer / 肿瘤研究与临床

Objective:To explore the setup errors of vacuum pad combined with breast bracket in linear accelerator intensity-modulated radiotherapy for breast cancer.Methods:The clinical data of 72 patients who received linear accelerator intensity-modulated radiotherapy after breast conserving surgery in Hai'an Hospital of Traditional Chinese Medicine from July 2017 to March 2022 were retrospectively analyzed. According to the radiotherapy fixation schemes, they were divided into vacuum pad group (24 patients), breast bracket group (27 patients) and vacuum pad combined with breast bracket group (21 patients). Cone-beam CT was used to analyze the setup errors of the fixation, and the mean value of the overall errors and the standard deviation of the system errors were calculated. The relative factors affecting the fixed setup errors were analyzed.Results:There were statistical differences among vacuum pad group, breast bracket group and vacuum pad combined with breast bracket group in the level of forward and backward (Z) direction translation error (2.11±0.41, 2.67±0.26 and 1.79±0.21) and Z direction rotation error (1.14±0.24, 1.05±0.21 and 0.91±0.22) ( F values were 45.86 and 6.21, both P < 0.05). The level of Z direction translation error in vacuum pad group was higher than that in vacuum pad combined with breast bracket group, and the difference was statistically significant ( t = 12.37, P = 0.001). The level of Z direction rotation error in breast bracket group was higher than that in vacuum pad combined with breast bracket group, and the difference was statistically significant ( t = 3.41, P = 0.001). In the breast bracket group, the planning target volume (PTV) extension boundary values in the left and right (X), up and down (Y), and Z directions were 2.02, 2.09 and 1.97; the PTV release boundary values in X, Y and Z directions of the vacuum pad group were 1.81, 2.07 and 2.25; the external boundary values of PTV in X, Y and Z directions of the vacuum pad combined with breast bracket group were 1.13, 1.51 and 1.49. The result of multifactor analysis showed that body mass index (BMI) ( OR = 4.208, 95% CI 1.438-12.312) and breast volume ( OR = 4.023, 95% CI 1.375-11.769) were the independent influencing factors of fixed setup errors (both P < 0.05). Conclusions:The application of vacuum pad combined with breast bracket in the fixed setup of linear accelerator intensity-modulated radiotherapy of breast cancer is helpful to reduce the fixed setup errors, but at the same time, the fixed setup errors is affected by the patient's BMI, breast volume and other factors.

Análisis comparativo in vitro de la resistencia adhesiva al cizallamiento de brackets metálicos adheridos a superficies dentarias tratadas con diferentes agentes blanqueadores / Comparative in vitro analysis of the adhesive resistance to the shear bond strength of metal brackets adhered to dental surfaces treated with different bleaching agents

RESUMEN: Objetivo: Evaluar y comparar el efecto de tres agentes blanqueadores en la resistencia adhesiva al cizallamiento de brackets metálicos. Método: Se cementaron 76 brackets en premolares humanos extraídos por indicación de ortodoncia. Se establecieron 4 grupos: (0) control, (1) esmalte tratado con Peróxido de Carbamida al 16%, (2) Peróxido de Hidrógeno al 35% y (3) tiras de blanqueamiento con Peróxido de Hidrógeno al 10%. Los brackets fueron cementados con Transbond XT (3M Unitek, EE.UU.). Se realizaron 5.000 ciclos de termociclado, luego se evaluó la resistencia adhesiva mediante una máquina Bisco y la cantidad de material adhesivo remanente según el índice adhesivo remanente (ARI). El análisis estadístico incluyó pruebas de Shapiro- Wilk, Kruskal -Wallis y Mann-Whitney. Resultados: Los grupos 0, 1, 2, 3 obtuvieron fuerzas de resistencia de 12.64, 11.06, 6.4 y 9.34 Mpa respectivamente con diferencia estadística entre los grupos (p <0.05). El ARI fue significativamente diferente en algunos grupos (p <0.05), indicando fallas adhesivas para el grupo 2 (p <0.05), cohesivas para el grupo control y de ambos tipos para los grupos 1 y 3. Conclusiones: El peróxido de hidrógeno al 35% reduce la resistencia adhesiva al cizallamiento en brackets metálicos sometidos a termociclado 24 horas luego del blanqueamiento.

ABSTRACT: Aim: To evaluate and compare the effect of three bleaching agents on the shear bond strength of metallic brackets. Method: Brackets were cemented on 76 human premolars extracted for orthodontic reasons. 4 groups were evaluated: (0) Control, (1) enamel treated with Carbamide Peroxide 16%, (2) Hydrogen Peroxide 35% and (3) Hydrogen Peroxide 10% "Whitening strips". All brackets were cemented using Transbond XT adhesive system (3M, Unitek, USA). All samples were thermocycled (5.000 cycles). Shear bond strength was evaluated with a Bisco machine and the amount of adhesive material at the base of the brackets and enamel surface was assessed using the adhesive remnant index (ARI). The statistical analysis included Shapiro-Wilk, Kruskal-Wallis and Mann-Whitney U tests. Results: The results of shear bond strength for groups 0, 1, 2, and 3 were 12.64, 11.06, 6.4 and 9.34 MPa respectively, with statistically significant differences between groups (p <0.05). ARI index was significantly different in some groups (p <0.05), indicating cohesive failure for control, adhesive failure for group 2 (p <0.05), adhesive and cohesive failure for groups 1 and 3. Conclusions: The 35% hydrogen peroxide office bleaching agent reduces adhesion values in the metal brackets thermocycled 24 hours after bleaching.

Influence of radiant exposure values from two third generation LED curing units on polymerization profile and microhardness of orthodontic composite under ceramic and metallic brackets

ABSTRACT Introduction: Third generation of LED light curing units might be used in short exposure periods for orthodontic brackets bonding. Objective: This study evaluated the effect of the different radiant exposure (RE) values: Manufacturers' instructions (MI), ½ MI, 1/4 MI and Turbo mode. Two third-generation LED curing units were used: VALO® and Bluephase 20i® . The degree of conversion (DC) and Vickers hardness (VHN) of an orthodontic composite (OC) (Transbond XT) under metallic (MB) or ceramic brackets (CB) were measured. Methods: OC was applied to the bracket base, which was then placed over an attenuated total reflectance (ATR) table coupled to an infrared light spectroscope, or to a glass surface for the VHN analysis. The specimens were light-cured and DC values were calculated. The VHN was obtained in a microhardness tester. The data were analyzed with 2-way ANOVA followed by Tukey's post-hoc test (pre-set α=0.05). Linear regression analysis evaluated the relationship between RE values and dependent variables. Results: CB allowed higher DC and VHN values than MB (p< 0.001). No significant difference was noted among groups when CB were used. For MB, MI groups showed the highest DC and VHN values. A significant, but weak relationship was found between delivered RE values and dependent variables. Conclusions: The decrease in RE values from third generation LED CU did not jeopardize the DC values when CB were used, but can compromise DC and VHN values when MB are used.

RESUMO Introdução: A terceira geração de LEDs fotopolimerizadores pode ser utilizada em curtos períodos de exposição para a colagem de braquetes ortodônticos. Objetivo: O presente estudo avaliou o efeito dos diferentes valores de irradiância (IR): instruções do fabricante (IF), ½ IF, » IF e modo Turbo. Dois fotopolimerizadores LED de terceira geração (VALO® e Bluephase20i®) foram utilizados. Foram mensurados o grau de conversão (GC) e a dureza Vickers (VHN) de um compósito ortodôntico (CO) (Transbond XT) sob braquetes metálicos (BM) ou cerâmicos (BC). Métodos: O compósito ortodôntico foi aplicado na base do braquete e foi posicionado sobre uma mesa de refletância total atenuada (ATR) acoplada a um espectroscópio de infravermelho ou a uma superfície de vidro para análise de VHN. As amostras foram fotopolimerizadas e os valores de GC foram calculados. O VHN foi obtido em um microdurômetro. Os dados foram analisados com ANOVA de 2 fatores seguida do teste post-hoc de Tukey (predefinido α = 0,05). A análise de regressão linear avaliou a relação entre os valores de IR e as variáveis dependentes. Resultados: BC permitiu valores maiores de GC e VHN do que BM (p<0,001). Nenhuma diferença significativa foi observada entre os grupos quando BC foi utilizado. Para BM, os grupos de IF mostraram os maiores valores de GC e VHN. Uma relação significativa, mas fraca, entre os valores de IR entregue e as variáveis dependentes foi encontrada. Conclusões: A diminuição dos valores de IR dos fotopolimerizadores LED de terceira geração não prejudicou os valores de GC quando BC foram utilizados, mas pode comprometer os valores de GC e VHN quando BM são utilizados.

Research progress on bracket bonding for dental fluorosis / 口腔疾病防治

@#Bonding of brackets to dental fluorosis has always been a difficult problem for clinicians. At present, clinical research has adopted several methods to facilitate bracket bonding, including prolonging etching time, enamel microabrasion, enamel ground, using adhesion promoter and laser etching. Prolonging etching time is suitable for mild-to-moderate dental fluorosis with easy chair-side operation; however, over-etching may cause severe tooth damage. Microabrasion can be applied to mild dental fluorosis while removing pigment deposition simultaneously; however, rubber dam protection is needed. Enamel ground can improve the bond strength to all kinds of dental fluorosis at the price of removing a relatively large amount of superficial enamel. Adhesion promoters might improve the bond strength of moderate to severe dental fluorosis; however, the current results conflict with one another. This needs further verification using larger-sample clinical trials. Laser etching has no effect on improving bond strength; however, it can remove pigment without destroying tooth enamel, which is worth further modification and enhancement.

Comparison of the impacts of two kinds of brackets on external apical root resorption in orthodontic treatment of bimaxillary protrusion patients / 中国组织工程研究

BACKGROUND: In orthodontic treatment, there will be different degrees of external apical resorption. Severe root resorption will reduce the root/shoot ratio, reduce the stability of teeth, and even cause teeth to loosen and fall out. OBJECTIVE: To compare the difference of external apical root resorption between high torque self-locking bracket and traditional straight wire bracket in orthodontic treatment of bimaxillary protrusion patients. METHODS: Forty-nine patients with bimaxillary protrusion, aged 13-16 years, who were treated in the Hospital of Stomatology of Southwest Medical University from January 2016 to December 2019, were enrolled in this study. The patients were divided into the high torque self-locking bracket group (n=24) and the traditional straight wire bracket group (n=25). Cone beam CT was taken before and after orthodontic treatment. The root morphology and length of maxillary central incisors and lateral incisors were observed by CS 3D Imaging Software. The amount of external apical root resorption between maxillary incisor and lateral incisor was calculated. This study was approved by the Medical Ethics Committee of Hospital of Stomatology of Southwest Medical University. RESULTS AND CONCLUSION: (1) The two groups after orthodontic treatment had achieved a good correction effect. The course of treatment was shorter in the high torque self-locking bracket group than that in the traditional straight wire bracket group (P 0.05). In the same appliance group, the amount of external apical root resorption of the maxillary central incisors was less than the lateral incisors (P < 0.05). (4) Results indicate that compared with the traditional straight wire bracket, the high torque self-locking bracket may have the advantages of short treatment course and low risk of apical absorption in the orthodontic treatment of bimaxillary protrusion.

Efectos de la interrelación arco-bracket, desde el microscopio electrónico de barrido / Effects of the arch-bracket interrelation, from the scanning electron microscope

Los alambres en ortodoncia son elementos activos que tienen la capacidad de almacenar energía y liberar fuerzas. Los brackets permiten la unión directa y selectiva entre el arco de alambre y las piezas dentarias, lo que optimiza el efecto de presiones específicas de forma precisa y controlada, transmitiendo el movimiento en los tres sentidos del espacio. Durante el tratamiento de ortodoncia, estos elementos podrían sufrir alteraciones estructurales impidiendo el movimiento dental óptimo. En el presente trabajo de investigación, se analizó la respuesta que tienen el arco de acero inoxidable 0.019" × 0.025" y el slot de brackets de zafiro, en el sector anterior del maxilar superior, cuando ejercen fricción entre sí, antes y después de ser utilizados clínicamente en un tratamiento de ortodoncia. Para esto, las muestras fueron lavadas con alcohol absoluto al 96 % y secadas para ser observadas en el microscopio electrónico de barrido ambiental (MEB) (ESEM - environmental scanning electron microscope), modelo FEI ESEM QuantaTM 200. Los arcos rectangulares fueron analizados por sus cuatro caras y cuatro aristas (superior, inferior, interna y externa; respectivamente) y los slots de brackets de zafiro fueron observados en un corte sagital y dividido en forma lineal en tres mediciones (interna, media y externa). Los datos obtenidos fueron volcados en una planilla de tabulación de datos para su análisis estadístico, mediante el test de normalidad de Shapiro-Wilk para medidas no paramétricas y el test de Fisher. En conclusión, las zonas más afectadas por el desgaste fueron las caras y aristas internas del arco de acero de 0.019" × 0.025", y la medición interna del slot de brackets de zafiro. Ambas presentaban una pérdida de la solución de continuidad en su estructura, evidenciando un área de mayor fricción(AU)

Orthodontic wires are active elements that have the ability to store energy and release forces. The brackets allow the direct and selective bonding between the wire arch and teeth, optimizing the effect of specific pressures in a precise and controlled way, transmitting movement in the three directions of space. During orthodontic treatment, these elements could undergo structural changes preventing optimal dental movement. In the current research work, the response that the 0.019" × 0.025" stainless steel archwire and the sapphire bracket slot have in the anterior sector of the upper jaw when they exert friction on each other, before and after being clinically used in an orthodontic treatment was analyzed. For this purpose, the samples were washed in 96% absolute alcohol and dried to be observed under the environmental scanning electron microscope ESEM (MEB - microscopio electrónico de barrido ambiental), model FEI ESEM QuantaTM 200. The rectangular archwires were analyzed on their 4 faces and 4 edges (upper, lower, internal and external) and the sapphire brackets slots were observed in a sagittal section and linearly divided into three measurements (internal, medium and external). The data obtained were put in a data tabulation spreadsheet for its statistical analysis by using the Shapiro-Wilk normality test for nonparametric measures, and the Fisher test. In conclusion, the areas most affected by wear were the internal face and edges of the 0.019" × 0.025" steel arch and the internal measurement of the sapphire brackets slot. They both presented loss of continuity in their structure, providing evidence of an area of greater friction(AU)

Evaluación de la adhesión de sistemas adhesivos de grabado total en esmalte dental bovino usando un agente desproteinizante: un estudio in vitro / Evaluation of adhesion of total etch adhesive systems on bovine dental enamel using a deproteinizing agent: an in vitro study

Introducción: Hoy en día, la mayoría de los pacientes requieren tratamiento de ortodoncia fija convencional, la cual utiliza procedimientos adhesivos afines con la superficie amelodentinaria. Aunque existen diferentes técnicas adhesivas que pueden ofrecer adecuados niveles de resistencia al desalojo, el uso del hipoclorito de sodio (NaClO) como agente desproteinizante no ha sido bien definido en materiales de cementación en aparatología ortodóncica convencional. Objetivo: El objetivo de este estudio fue determinar los niveles de resistencia al desalojo con pruebas de microtensión y análisis topográfico con microscopia electrónica de barrido. Material y métodos: 20 bloques de esmalte bovino fueron expuestos superficialmente a soluciones acondicionadoras (ácido ortofosfórico al 37%) con y sin agente desproteinizante (NaClO al 5.25%); finalmente, brackets individuales de ortodoncia fueron cementados con sistemas adhesivos y resinas compuestas de casas comerciales (Ormco y 3M). Las pruebas de resistencia al desalojo fueron realizadas con una máquina de fuerzas universales y el análisis topográfico con microscopia electrónica de barrido. Resultados: El uso del NaClO al 5.25% y la marca Ormco tuvieron estadísticamente los mejores niveles de adhesión que el grupo sin desproteinización y la casa comercial 3M, respectivamente. La topografía adamantina expuesta al agente desproteinizante mostró características de superficie relacionadas con el patrón de grabado tipo I. Conclusión: El uso de un agente desproteinizante (NaClO 5.25%) así como una marca comercial (Ormco) en particular podrían definir el aumento en los niveles de adhesión en superficies adamantinas con aparatología ortodóncica convencional (AU)

Introduction: Nowadays, patients require conventional fixed orthodontic treatment, which uses adhesive procedures related to the dentinal denture surface. Although there are different adhesive techniques that can offer adequate levels of bonding resistance, the use of NaClO as a deproteinizing agent has not been well defined in cementing materials in conventional orthodontic appliances. Objective: The objective of this study was to determine the levels of bond resistance using micro tension tests and topographic analysis with scanning electron microscopy. Material and methods: Twenty-blocks of bovine enamel were exposed superficially to conditioning solutions (37% orthophosphoric acid) with and without deproteinizing agent (5.25% NaClO); finally, individual orthodontic brackets were cemented with adhesive systems and resin composites of different trademarks (Ormco and 3M). Bonding resistance tests were performed with a universal force machine and topographic analysis was made with scanning electron microscopy. Results: The use of 5.25% NaClO and the Ormco brand had statistically better levels of adhesion than the group without deproteinization and the 3M brand, respectively. Adamantine topography exposed to the deproteinizing agent showed surface characteristics related to the type I etching pattern. Conclusion: The use of a deproteinizing agent (NaClO 5.25%) as well as a trademark (Ormco) in particular conditions could define the increase in adhesion levels on adamantine surfaces with conventional orthodontic appliances (AU)

The use of epigallocatechin gallate prevents white spot lesions during orthodontic treatment with fixed appliances / 中国组织工程研究

BACKGROUND: Plenty of studies have already proved the effective usage of epigallocatechin gallate (EGCG) in clinical treatment. However, no current research has focused on the application of EGCG in preventing white spot lesions (WSLs) during orthodontics treatment with fixed appliances. OBJECTIVE: To study the value of EGCG in the prevention of WSLs during orthodontic treatment with fixed appliances. METHODS: In total 50 patients undergoing orthodontic treatment with fixed appliances were carefully screened and enrolled. Split-mouth design was adopted: the right side of teeth received experimental adhesive (1 g/L EGCG + Adper™ Single Bond 2); the left side of teeth acted as control. All the other clinical procedures and materials used were same. The enamel demineralization index (EDI) and the WSLs prevalence of targeted teeth (16, 11, 46, 26, 31, and 36) were detected at 3, 6, and 12 months during the treatment, and the percentage of bracket bonding failure was calculated for each group. The study protocol was implemented in line with the relevant ethical requirements of Liuzhou People’s Hospital. Patients and their guardians were fully informed of the whole trial procedures. RESULTS AND CONCLUSION: In this trial, the percentage of bracket bonding failure was significantly different between the EGCG group and control group (P > 0.05). After 3 months of treatment, the values of WSLs and EDI had no significant difference between the EGCG group and control group (P > 0.05). However, after 6 months and 12 months treatment, the EGCG group manifested significantly lower WSL and EDI values than the control group (P < 0.05). Therefore, addition of the adhesive containing 1 g/L EGCG has a considerable effect in preventing enamel demineralization and the occurrence of WSLs without influencing the enamel bonding strength, and it has a long-time effect which deserves the clinical expansion.

Comparison of WALA ridge and dental arch dimensions changes after orthodontic treatment using a passive self-ligating system or conventional fixed appliance

Objective: To compare changes in WALA ridge and mandibular dental arch dimensions in orthodontic patients treated with a passive self-ligating system and conventional appliances. Design: Original paper. Setting: Orthodontic department at Inga University Center, Maringá, PR, Brazil. Materials and Methods: Pretreatment (T1) and posttreatment (T2) dental casts of 60 patients with Class I malocclusion treated with slight to moderate crowding that were divided into two groups. Group 1: 30 patients treated with a passive self-ligating system, at a mean initial age of 17.68 years and mean treatment time of 2.31 years. Group 2: 30 patients treated with conventional appliances, at a mean initial age of 19.23 years and mean treatment time of 2.56 years. Measurements were taken using a digital caliper directly on pre and posttreatment dental casts to evaluate the transversal dimension behavior of the mandibular dental arch and the WALA ridge width. Results: Self-ligating group presented an increase in WALA ridge width and mandibular transversal dimensions significantly greater than the conventional group, with the exception of intermolar cusp tip distance and intercanine WALA ridge. There was no statistically significant difference between the groups. There was also observed a significantly greater increase of the transversal buccal axis dimensions in the premolar area when compared to the WALA ridge increase in both groups. Conclusions: Treatment with a passive self-ligating system resulted in a significantly greater increase of the WALA ridge width and mandibular arch dimensions when compared to conventional appliance.

Comparison of Shear Bond Strength of Occlusal Pad Debonding Pliers Before and After Er-YAG Laser Application: An In vitro Study

Background: Er-YAG laser showed to be effective in debonding ceramic bracket from the enamel surface. Until lately, no previous study was conducted to assess the outcome of the laser in debonding ceramic brackets from tooth surface comparing it with conventional occlusal pad debonding pliers. Materials and methods: Total 60 ceramic brackets were bonded on the tooth surface which was divided randomly into 2 groups. One was assigned as a control non-lased group and the other was experimental lased groups. Er-YAG laser irradiated the experimental groups at the power of 5 W for 10 seconds with swiping motion and 50% air-water cooling. In the lased experimental group, the laser was applied at energy of 250 mJ, 20 Hz frequency, and pulse duration of 100 μs. Results: Shear bond strengths and adhesive remnant index scores were statistically calculated. A highly significant difference of SBS between the non-lased control group and the lased experimental group was observed (p<0.000). A non-significant difference in ARI scores was observed when the non-lased control group was compared with the lased experimental group. Conclusion: It could be concluded that Er-YAG laser is effective in ceramic bracket debonding. This protocol promotes debonding without bracket fracture or enamel surface cracks or damage.

Effect of Fixed Orthodontic Appliances on Subgingival Plaque Microbiota

Introduction: The present study aimed to examine changes insubgingival microbiota and clinical parameters before and afterplacement of bracket.Methods: Clinical parameters such as plaque index (PI),probing depth (PD), bleeding on probing (BOP), clinicalattachment level (CAL), and gingival index (GI) were recorded.Additionally, subgingival microbial samples were collected from30 individuals aged between 13 and 25.A total of 15 individualsas the control group were matched in terms of age and sexwithout needing orthodontic treatment using specific primers.Furthermore, SYBER Green Real-Time PCR was conducted todetermine bacterial flora in stored samples. All the mentionedprocedures were reexamined in the experimental and controlgroups three months after band and bracket bonding. Adescriptive analysis was conducted, and paired t-test andWilcoxon test were employed for differences between thegroups (P<0.05).Results: No changes in the level of clinical attachment wereseen, but scores for plaque index, bleeding on probing andgingival index increased 3 months after placement of bracketin the experimental group (P<0.05). P. nigrescence in theexperimental group increased after placement of bracketscompared to the control group, but P. gingivalis and T.Denticola proportions increased.Conclusions: Fixed orthodontic appliances may raise thegrowth of periodontopathogenic bacteria and consequentlyleads to gingival inflammation without destructive effect ondeep periodontal tissues.

Surface analysis of metal clips of ceramic self-ligating brackets / 대한치과교정학회지

OBJECTIVE: The aim of this study was to analyze the surface composition, roughness, and relative friction of metal clips from various ceramic self-ligating brackets. METHODS: Six kinds of brackets were examined. The control group (mC) consisted of interactive metal self-ligating brackets while the experimental group (CC, EC, MA, QK, and WA) consisted of interactive ceramic self-ligating brackets. Atomic force microscopy-lateral force microscopy and scanning electron microscopy-energy-dispersive X-ray spectroscopy were used to analyze the surface of each bracket clip. RESULTS: All the clips in the experimental groups were coated with rhodium except for the QK clip. The results showed that the QK clip had the lowest average roughness on the outer surface, followed by the MA, EC, WA, and CC clips. However, the CC clip had the lowest average roughness on the inner surface, followed by the QK, WA, MA, and EC clips. The QK clip also had the lowest relative friction on the outer surface, followed by the MA, EC, CC, and WA clips. Likewise, the CC clip had the lowest relative friction on the inner surface, followed by the QK, WA, MA, and EC clips. CONCLUSIONS: The surface roughness and relative friction of the rhodium-coated clips were generally higher than those of the uncoated clips.

Effect of different combinations of bracket, archwire and ligature on resistance to sliding and axial rotational control during the first stage of orthodontic treatment: An in-vitro study / 대한치과교정학회지

OBJECTIVE: This study was performed to explore the effect of different bracket, archwire, and ligature combinations on resistance to sliding (RS) and rotational control in first-order angulation. METHODS: Three types of brackets (multi-level low friction [MLF], self-ligating, and conventional brackets) coupled with four nickel-titanium archwires (0.012, 0.014, 0.016, and 0.018-inch diameter) and two stainless steel ligatures (0.20 and 0.25 mm) were tested in different first-order angulations (0°, 2°, 4°, 6°, 8°, 10°, 15°, 20°) by using an Instron universal mechanical machine in the dry state at room temperature. RS value was evaluated and compared by one-way ANOVA. RESULTS: Under the same angulation, the RS values showed the following order: conventional brackets > MLF brackets > self-ligating brackets. The RS was the highest for conventional brackets and showed a tendency to increase. The RS for MLF brackets coupled with thinner archwires and ligatures showed a similar tendency as the RS for the self-ligating bracket. In contrast, the RS for MLF brackets coupled with thicker archwires and ligatures increased like that for conventional brackets. MLF brackets showed the greatest range of critical contact angles in first-order angulation. CONCLUSIONS: The RS in first-order angulation is influenced by bracket design, archwire, and ligature dimension. In comparison with self-ligating and conventional brackets, MLF brackets could express low friction and rotational control with their greater range of critical contact angles.

Research progress of orthodontic indirect bonding technology / 口腔疾病防治

@#Accurate positioning of brackets is a necessary condition for ideal orthodontic treatment. Traditional bracket bonding technology has certain limitations, such as long operation time and poor accuracy. Indirect bonding technology is a method that bonding brackets on the model through intraoral impression or scanning, and then the brackets are accurately bonded to the tooth crowns using a transfer tray. In this article, the progression of transfer trays and adhesive agents, the application of digital technology in indirect bonding technology, indirect bonding for invisible appliances, and the prospect of this technology are reviewed. The literature review results show that indirect bonding technology can locate the bracket accurately, the operation is simple, the patient’s experience is comfortable, and the clinical efficiency can be significantly improved, the photocurable adhesive is an ideal adhesive for indirect bonding technology. With the development of digital technology, indirect bonding technology will be able to locate the brackets with increasing accuracy, thus achieving the "digital precision movement" of the teeth. The bonding technology of invisible appliance accessories is essentially a type of indirect bonding technology, It requires indirect bonding technology and digital technology to highly fit the needs of computer design accessories for the visual tooth movement and the use of indirect bonding technology to accurately bond accessories, ultimately achieving the desired tooth movement. Indirect bonding technology will play an increasingly important role with the development of digital technology and invisible correction technology.

Influence of the SmartClip self-ligating bracket on plaque control in orthodontic patients / 口腔疾病防治

Objective@#To explore the influence of the SmartClip self-ligating bracket and traditional metal bi-wing brackets on plaque control and to provide a reference for the oral healthcare of orthodontic patients.@*Methods@#The patients were divided into the SmartClip self-ligating bracket group, the metal bi-wing bracket group, and the control group, consisting of untreated volunteers, and the patients were examined before treatment, 1 month after the treatment started, 3 months after the treatment started, and when the treatment ended. The oral hygiene status was recorded at four time points, and the plaque index of the following six teeth was compared among the time points: the upper-right central incisor (UR1), the lower-left central incisor (LL1), the upper-right first molar (UR6), the lower-left first molar (LL6), and the upper left canine (UL3) and the lower-right canine (LR3).@*Results@#Compared with before treatment, after first month, third month and end of treatment the plaque index of LL1, LR3, LL6 and UR6 in both the SmartClip self-ligating bracket group and the traditional metal bi-wing bracket group was increased, and the difference was statistically significant (P < 0.05). There was no significant difference in PLI index between the end of treatment and 3 months after orthodontic treatment (P > 0.05). There was no statistically significant difference in PLI index in the control group at each time period (P > 0.05). After three months of orthodontic treatment, the plaque index of LL1 and LR3 in the SmartClip self-ligating bracket group was higher than that in the traditional metal bi-wing bracket group, and the difference was statistically significant (P < 0.05).@*Conclusion@#Lower anterior and posterior areas are susceptible to plaque accumulation in treatment with fixed orthodontic appliances. The SmartClip self-ligating bracket system has no advantage over the traditional metal bi-wing bracket in terms of oral hygiene.