Effect of miniscrew placement height on the distribution of biological forces produced by clear aligner for mandibular molar distalization / 口腔疾病防治

Objective@#To explore the effect of different miniscrew placement heights on the distribution of biological forces produced by clear aligner combined with intramaxillary traction for mandibular molar distalization, to identify the miniscrew location that is conducive to the protection of lower anterior tooth anchorage and to provide a reference that can be used when designing clinical treatments.@*Methods@#Mimics, GeomagicStudio 2017, SolidWorks 2016, and Ansys workbench were used to establish finite element analysis models and perform mechanical analysis under the following six working conditions: working condition 1 was the control group without miniscrews; working conditions 2 to 5 had miniscrew in the buccal bone cortex between the first and second molars of the lower jaw 10 mm, 7 mm, 4 mm, and 1 mm from the top of the alveolar crest, respectively; working condition 6 had the miniscrew in the center of the buccal tongue at the anterior edge of the ascending branch of the lower jaw 5 mm above the occlusal plane.@*Results@#On the sagittal axis, miniscrew anchorage caused distal displacement of all teeth. Compared to the control group, in the miniscrew group, the displacement of the anterior molars exceeded that of the second molars. On the vertical axis, the result in the control group was similar to backward bending; the results in the miniscrew groups resembled the effect of a lever, lowering the lateral incisors and canines and raising the central incisors and first premolars. On the coronal axis, the second premolars and the first molars showed lingual displacement in the control group, and only the premolars and first molars showed lingual displacementin the miniscrew groups. The canines were the teeth that were most strongly affected by the change in miniscrew placement height.@*Conclusion@#The higher the miniscrew position is, the stronger the protective effect on the anterior anchorage. According to the miniscrew placement height, the mandibular arch should be properly narrowed, the central incisors and first premolars should be lowered, and the lateral incisors and canines should be raised when designing clinical treatments.

Effect of miniscrew-assisted rapid palatal expansion on mandibular position / 口腔医学

Objective@#To explore the effect of miniscrew-assisted rapid palatal expansion (MARPE) on mandible position in the treatment of adult skeletal Class Ⅰ malocclusion with maxillary transverse deficiency. @*Methods@#In this retrospective study, 20 cases of adult skeletal Class Ⅰ malocclusion with maxillary transverse deficiency treated with MARPE in our hospital from July 2019 to March 2022 were selected as research objects. CBCT data of three time points before treatment (T0), immediately after expansion (T1) and six months after retention (T2) were collected. The head position was standardized and calibrated by Dolphin software, and then mandible landmarks (left and right Condylion, left and right Gonion, Menton) were positioned. The linear distance changes of each landmark relative to the reference plane of coronal plane, axial plane and sagittal plane were measured, which represented the sagittal, vertical and horizontal displacement of mandible respectively. Repeated measurement ANOVA and LSD multiple comparison were used to evaluate the position change of each landmark.@*Results @#The Menton and right Gonion rotated clockwise at T1, and relapsed to the initial position at T2. No lateral displacement of Menton was found.@*Conclusion@#When MARPE is used to treat skeletal Class Ⅰ malocclusion with maxillary transverse deficiency, it causes a transient clockwise rotation of the mandiblar. The mandible does not show sagittal, vertical and horizontal position changes in long-term evaluation.

Tratamiento de Superficie utilizados en Microtornillos de Ortodoncia y su Efecto en la Estabilidad Primaria y Secundaria: Revisión Bibliográfica

Resumen: Los microtornillos de ortodoncia corresponden a dispositivos de anclaje temporal que sirven como coadyuvantes en el tratamiento ortodóncico y cuyo uso se ha ido incrementando en el último tiempo. Las fallas de los microtornillos tienden a ocurrir durante la primera semana de inserción por lo que mejorar la estabilidad es un paso importante para mejorar la confiabilidad del tratamiento. Una posible solución a esto es modificar la superficie del microtornillo. Objetivo: Identificar en la literatura actual los tratamientos de superficie más utilizados que favorezcan la estabilidad primaria y secundaria en el éxito de los microtornillos en ortodoncia. Material y método: Se realizó una búsqueda en Pubmed y EBSCO con los términos en idioma inglés "miniscrew"/"mini implant" AND "surface", "treatment" and "stability". Se incluyeron los estudios realizados in vivo con el objetivo de comparar y/o evaluar el efecto de los tratamientos realizados en la superficie del microtornillo en el éxito o estabilidad de éste, artículos disponibles en inglés y español. Se excluyeron estudios realizados en implantes dentales y/o médicos, in vitro, estudios clínicos sin grupo control. Resultados: 25 publicaciones fueron utilizadas en la revisión, habiendo 11 tipos de tratamiento de superficie estudiados. La generación de ma trices de nanotubos de óxido de titanio, fotofuncionalización mediada por rayos ultravioleta y anodizado de superficie evidenciaron aumento de la estabilidad de los microtornillos. El uso de técnicas convencionales: grabado ácido, arenado-grabado ácido, no es concluyente en cuanto a su efecto en la estabilidad. Conclusión: Hay escasa evidencia sobre los tratamientos de superficie realizados en microtornillos de ortodoncia para la mejora de su estabilidad. Técnicas pioneras como la generación de matrices de nanotubos de óxido de titanio, fotofuncionalización mediada por rayos ultravioleta y anodizado de superficie evidenciaron aumento de la estabilidad de los microtornillos, siendo necesaria la replicación de los estudios en humanos. La utilización de técnicas convencionales tales como grabado ácido y arenado-grabado ácido, no es concluyente en cuanto a su efecto en la estabilidad de los microtornillos.

Abstract: Orthodontic miniscrews are temporary anchoring devices that help as adjuvants in orthodontic treatment and whose use has increased in recent times. Miniscrew failures can happen during the first week of insertion, so improving stability is an important step to enhance treatment reliability. A possible solution to this issue is to modify the miniscrew surface. Objective: To identify in the current literature the most widely used surface treatments that favor the primary and secondary stability and success of orthodontic miniscrews. Material and method: A search was made in Pubmed and EBSCO with the English terms "miniscrew"/"mini implant" AND "surface", "treatment" and "stability". In vivo studies were included with the aim of comparing and/or evaluating the effect of the treatments performed on the miniscrew's surface and their success or stability, articles available in English and Spanish. Studies performed in dental and/or medical implants, in vitro, clinical studies without control group were excluded. Results: 25 publications were used in the review, with 11 types of surface treatment studied. The generation of titanium oxide nanotube matrices, ultraviolet-mediated photofunctionalization and surface anodizing showed an increase in the stability of the miniscrews. The use of conventional techniques: acid etching, sandblasting-acid etching, is inconclusive as to its effect on stability. Conclusion: There is little evidence of surface treatments performed on orthodontic miniscrews to improve their stability. Pioneering techniques such as the generation of titanium oxide nanotube matrices, ultraviolet-mediated photofunctionalization and surface anodizing showed increased stability of the miniscrews, and require their replication on human studies. The use of conventional techniques such as acid etching and acid sandblasting-etching is inconclusive as to its effect on the stability of the miniscrews.

Abordaje quirúrgico para verticalización de tercer molar a través de minitornillo. ¿es necesaria la extracción? / Surgical approach for the verticalization of the third molar through a miniature screw. Is extraction necessary?

RESUMEN Anteriormente se reportaba en la literatura que terceros molares en mala posición como horizontales, mesio y disto angulados, era indicación clara para la extracción del diente. La verticalización de molares con minitornillo en la rama mandibular, corresponde a una técnica ortoquirúrgica en la cual a través de movimientos sobre el eje longitudinal de un diente, se logra un buen posicionamiento en la arcada y la preservación del diente, evitando la extracción. El propósito del trabajo es describir el abordaje quirúrgico y resultados, de la verticalización de un tercer molar inferior incluido en posición mesioangular, a través de la colocación de minitornillo utilizando la rama mandibular como anclaje de un paciente femenino de 35 años de edad.

ABSTRACT Previously, it was reported in the literature that third molars in poor position, such as horizontal, mesial and disto angulated, were a clear indication for tooth extraction. The verticalization of molars with a miniscrew in the mandibular branch corresponds to an ortho-surgical technique in which, through movements on the longitudinal axis of a tooth, a good positioning in the arch and preservation of the tooth is achieved, avoiding extraction. The purpose of this work is to describe the surgical approach and results of the verticalization of an included lower third molar in the mesioangular position, through the placement of a miniature screw using the mandibular branch as anchorage in a 35-year-old female patient.

Stability of immediately loaded 3 mm long miniscrew implants: a feasibility study

ABSTRACT Introduction: Shorter miniscrew implants (MSIs) are needed to make orthodontics more effective and efficient. Objective: To evaluate the stability, insertion torque, removal torque and pain associated with 3 mm long MSIs placed in humans by a novice clinician. Methods: 82 MSIs were placed in the buccal maxillae of 26 adults. Pairs of adjacent implants were immediately loaded with 100g. Subjects were recalled after 1, 3, 5, and 8 weeks to verify stability and complete questionnaires pertaining to MSI-related pain and discomfort. Results: The overall failure rate was 32.9%. The anterior and posterior MSIs failed 35.7% and 30.0% of the time, respectively. Excluding the 10 MSIs (12.2%) that were traumatically dislodged, the failure rates in the anterior and posterior sites were 30.1% and 15.2%, respectively; the overall primary failure rate was 23.6%. Failures were significantly (p= 0.010) greater (46.3% vs 19.5%) among the first 41 MSIs than the last 41 MSIs that were placed. Excluding the traumatically lost MSIs, the failures occurred on or before day 42. Subjects experienced very low pain (2.2% of maximum) and discomfort (5.5% of maximum) during the first week only. Conclusions: Shorter 3 mm MSIs placed by a novice operator are highly likely to fail. However, failure rates can be substantially decreased over time with the placement of more MSIs. Pain and discomfort experienced after placing 3 mm MSIs is minimal and temporary.

RESUMO Introdução: Mini-implantes (MIs) mais curtos são necessários para uma Ortodontia mais eficiente e efetiva. Objetivo: Avaliar a estabilidade, torque de inserção e de remoção e dor associada a MIs de 3mm instalados em humanos por um ortodontista principiante. Métodos: 82 MIs foram instalados na região vestibular da arcada superior de 26 adultos. Pares de mini-implantes adjacente receberam carga imediata de 100g. Após 1, 3, 5 e 8 semanas, os pacientes foram reavaliados para verificar a estabilidade e preencher um questionário sobre a dor e o desconforto relacionados aos MIs. Resultados: A taxa geral de falhas foi de 32,9%, sendo de 35,7% para os MIs anteriores e 30% para os MIs posteriores. Excluindo os 10 MIs que foram perdidos por trauma (12,2%), a taxa de falha nas regiões anterior e posterior foram de 30,1% e 15,2%, respectivamente e ocorreram no 420 dia ou antes. A taxa geral de falha primária foi de 23,6%. A taxa de falha foi significativamente maior (p=0,010) nos primeiros 41 MIs do que nos 41 últimos (46,3% vs. 19,5%). As experiências relacionadas à dor foram baixas (2,2% máximo), assim como ao desconforto (5,5% máximo) durante a primeira semana. Conclusão: MIs de 3mm instalados por um novato são mais propensos a falhas. Porém, as taxas de falha podem diminuir substancialmente com a instalação de mais MIs com o decorrer do tempo. A dor e o desconforto após a instalação desses dispositivos são mínimos e temporários.

Treatment of bimaxillary protrusion using intra- and extra-alveolar miniscrews associated to self-ligating brackets system

ABSTRACT Introduction: Moderate and severe bimaxillary protrusion impair the passive lip sealing and the facial and smile esthetics. The extraction of premolars can be avoided by the use of skeletal anchorage to retract both dental arches. This approach brings many advantages such as: prevents premolars extraction; simplifies orthodontic mechanics; there is no volume reduction of a premolar when smiling; control of overbite and gingival exposure. The utilization of this therapeutic approach, when associated with self-ligating brackets, can bring the possibility of spacing the appointments without damage to the treatment efficiency, and allows selection of the most appropriate torque prescriptions for each case. The intra-alveolar miniscrews are indicated for mild cases of bimaxillary protrusion, while extra-alveolar miniscrews may also be indicated for more severe cases. Objective: To report the treatment of three cases of mild, moderate and severe bimaxillary protrusion, in which intra- and extra-alveolar miniscrews were used, according to the retraction required. Conclusion: The retraction of both upper and lower dental arches using orthodontic intra- and extra-alveolar miniscrews, associated with self-ligating brackets, is an excellent tool to correct mild to severe bimaxillary protrusion, thus reducing the need of premolar extraction and simplifying the orthodontic management.

RESUMO Introdução: As biprotrusões moderadas e severas dificultam o selamento labial passivo, comprometem a estética facial e do sorriso. As extrações de pré-molares podem ser evitadas quando se utiliza a ancoragem esquelética como recurso para retrair ambas as arcadas. Essa abordagem traz as seguintes vantagens: evita que o paciente seja submetido ao processo da extração dos pré-molares; simplifica a mecânica ortodôntica; não reduz o volume de um pré-molar de cada lado no sorriso; e auxilia no controle da sobremordida e da exposição gengival. A utilização dessa terapêutica, quando associada aos aparelhos autoligáveis, possibilita maiores intervalos entre as consultas, sem comprometer a eficiência do tratamento, e permite a seleção dos torques mais adequados para essa mecânica. Os miniparafusos intra-alveolares podem ser utilizados na correção de biprotrusões mais suaves, enquanto os extra-alveolares podem ser indicados, também, nos casos mais severos. Objetivo: Relatar os tratamentos de três casos clínicos de biprotrusão leve, moderada e severa, respectivamente, efetuando a retração das arcadas em uma única fase, utilizando miniparafusos intra- e extra-alveolares, conforme a magnitude da retração necessária. Conclusão: A retração das arcadas superior e inferior com miniparafusos ortodônticos intra- e extra-alveolares associados aos aparelhos autoligáveis é um excelente recurso para a correção das biprotrusões de suave a severa, diminuindo a necessidade de extrações de pré-molares e simplificando a mecânica ortodôntica.

Vectores de fuerza generados con microimplantes en la retrusión en masa del sector anterosuperior / Force vectors generated by microimplants in the mass retrusion of the anterosuperior sector

La incorporación de los microimplantes a la ortodoncia revoluciona la mecánica de cierre de espacios por deslizamiento, ya que mejora sus dos puntos "débiles": el anclaje y el control dentario tridimensional. El propósito de este trabajo es determinar los vectores de fuerza y el tipo de movimiento generado en la retrusión en masa del sector anterosuperior, según las distintas ubicaciones de los microtornillos y la altura del brazo de la palanca anterior. Las nuevas tendencias de utilización de microimplantes para la retrusión producen vectores de fuerza horizontales y verticales y momentos según su ubicación y según el punto de aplicación de la fuerza. Debido a esto último, el conocimiento de la biomecánica adquiere especial importancia para un correcto resultado final en el tratamiento ortodóncico. Un diagnóstico certero, un objetivo de tratamiento claro y realista y la elección de la aparatología correcta se verán frustrados una y otra vez de no contar con un correcto conocimiento de las reacciones biológicas ante las fuerzas ejercidas (AU)

The incorporation of miniscrew into orthodontics revolutionizes the mechanics of sliding closure spaces, since it improves its two "weak" points: anchoring and three-dimensional dental control. The purpose of this work is to determine the force vectors and the type of movement generated in the mass retrusion of the anterior superior sector according to the different miniscrew´s locations and the anterior lever arm´s height. The new trends in the use of miniscrews for retrusion produce horizontal and vertical force vectors and moments according to their location and the point of application. In consequence, the knowledge of biomechanics acquires special importance to get a correct final result in orthodontic treatment. Not having a detailed knowledge of the biological reactions on the forces exerted will cause that the accurate diagnosis, the clear and realistic treatment objective, and the choice of the correct appliances to be frustrated over and over (AU)

Una Descripción General y Actualizada de Miniplacas y Minitornillos. Efectos Dentoalveolares y Esqueléticos / A General and Updated Description of Miniplates and Miniscrews. Dentoalveolar and Skeletal Effects

RESUMEN: En ortodoncia, las miniplacas se utilizan como dispositivo de anclaje temporal (TAD) para la realización de movimientos dentales que permiten el uso de fuerzas ortopédicas en ellos. En comparación con los mini tornillos, las miniplacas tienen la ventaja de una tasa de falla muy baja, pero la desventaja es que para la extracción se necesita el mismo acto quirúrgico que se realizó para la instalación. El objetivo de este estudio es realizar una revisión bibliográfica de las indicaciones de miniplacas en pacientes con mordidas abiertas, clase II y anomalías de clase III, y buscar cómo las miniplacas han mejorado los tratamientos de ortodoncia. La información principal se reunió buscando en PubMed con las palabras clave enumeradas a continuación. Afirmamos que las miniplacas están indicadas para la retracción en masa de la arcada, donde se observó que la fuerza de 150 g aplicada en los molares superiores es suficiente no solo para empujar los molares hacia atrás en una clase I corregida, sino también para iniciar la retracción de premolares, caninos e incisivos. En pacientes con mordida abierta, las miniplacas se definen como un método seguro, una alternativa rápida y menos costosa a la cirugía ortognática. Y en pacientes de las clases II y III se utilizan sin producir efectos dentoalveolares que sustituyan a los dispositivos extraorales como máscaras, con dispositivos intraorales y elásticos (BAMP).

ABSTRACT: In orthodontics, miniplates are used as a Temporary Anchoring Device (TAD) for the purpose dental movements, allowing the use of orthopedic forces. In comparison with mini-screws, miniplates have the advantage of a very low rate of failure. Nonetheless, their removal requires the same surgical procedure as during installation, which is an obvious disadvantage. The aim of this study is to review the indications of miniplates in patients with open bite, class II and class III anomalies, and review how miniplates improved orthodontics treatments. Information was obtained by a search in PubMed with the keywords listed below. Miniplates are indicated for retraction in mass of the arcade, where it was seen that the force of 150 g applied on maxillary molars, is sufficient not only to push the molars back into a corrected class I, but also to initiate retraction of premolars, canines, and incisors. In open-bite patients, mini plates, are achieved as a safe method, that is quick and a less expensive alternative to orthognathic surgery. Further, in class II and III patients they are used without producing dentoalveolar effects replacing extraoral devices as facemasks, with intraoral devices and elastics. (BAMP).

Factors affecting the clinical success rate of miniscrew implants for orthodontic treatment / 中国组织工程研究

BACKGROUND: During the orthodontic treatment, the results of related reports on potential risk factors affecting the clinical success rate of miniscrew implants are inconsistent. The influential factors that clinicians concern are not all included in this study, and the conclusions from animal experiments are difficult to apply to clinical practice directly. Therefore, what factors affect the clinical success rate of miniscrew implants need further thorough and systematic research. OBJECTIVE: To investigate the factors that influence the clinical success rate of miniscrew implants used as orthodontic anchorage. METHODS: A total of 114 patients with oral implants, including 42 males and 72 females, aged (19. 26±9. 19) years were included in this study. A total of 253 miniscrew implants were implanted as orthodontic anchorage. The following influential factors were included: Gender, age, vertical skeletal facial pattern, implant site, implant arch, soft tissue type at the implant site, oral hygiene status, diameter and length of the miniscrew implants, implantation method, implantation angle, stress loading timing and intensity, and clinical use. Logistic regression analysis was used to study the correlation between success rate and all variables. Analysis of variance was used to test the effect of each variable on clinical success rate. This trial protocol was approved by the Medical Ethics Committee of Sichuan University. RESULTS AND CONCLUSION: Among 253 successful miniscrew implants, the overall success rate was 88. 54% with an average loading period of 9. 5 months. The average loading period of the 29 failed miniscrew implants was 2. 3 months. The chi-square test, Fisher exact test and Logistic regression revealed that age, oral hygiene, vertical skeletal facial pattern, and implant site were significantly correlated with clinical success rate (P 0. 05). These results suggest that to minimize the failure of miniscrew implants, proper oral hygiene instruction and effective supervision should be given to patients, in particular to those young (< 12 years) high mandibular plane patients.

Advances and applications of the maxillary expansion technique / 口腔疾病防治

@#Transverse maxillary deficiency is a common malocclusion in the clinic. Palatal expansion techniques are commonly used in the treatment of maxillary transverse deficiency. Traditional palatal expansion techniques have good effects on the treatment of children and adolescents whose palatal suture has not yet closed, but the effects on adult patients are unsatisfied. New palatal expansion techniques, such as miniscrew-assisted rapid palatal expansion and surgical-assisted maxillary expansion, have increased the age-related indications for palatal expansion, and their bone expansion effect has been strengthened. With the development of CAD/CAM technology and 3D printing technology, techniques such as Invisalign and personalized appliances have been developed and have promising application prospects. To provide references for the clinical treatment of maxillary transverse deficiency, palatal expansion techniques are reviewed from the following aspects: mechanism and indications, expansion pattern, traditional and new palatal expansion appliances, stability and retention of palatal expansion, outlook of future expanders, etc.

Effect of personalized miniscrew-assisted rapid palatal expander on expansion of the median palatal suture in adults / 口腔疾病防治

Objective@# To investigate the manufacturing procedures of personalized miniscrew-assisted rapid palatal expanders (pMARPE) using digital technologies and to evaluate the effect of the expanders when expanding the midpalatal suture of an adult. @*Methods@# Digital technologies were used to make pMARPE, which was used to treat a 21-year-old woman with maxillary transverse deficiency (MTD). The relevant literature on MARPE was reviewed.@* Results@#PMARPE could be manufactured using intraoral digital scanning, computer-aided design and computer-aided manufacturing(CAD/CAM ), and 3D printing technologies. After expansion, the width of the anterior midpalatal suture, posterior midpalatal suture and maxillary skeletal width increased by 3.9 mm, 3.2 mm and 4.7 mm, respectively. There was no significant change in the inclination of maxillary first molars, and the height of alveolar ridge decreased slightly. It could be seen that using digital technologies to manufacture personalized expanders was possible for MARPE , and the initial stability of miniscrews played an important role in the expansion success rate, the increase of molar inclination is composed of many parts, and the decrease of alveolar ridge height may be overestimated due to the measurement method, as shown by a literature review. @*Conclusion@#The midpalatal suture of an adult patient with MTD could be expanded by pMARPE. However, the effect of this expander on the inclination of the first molar and alveolar bone height needs to be further studied with a larger sample size.

Evaluation of Change in Dento-Skeletal Vertical Dimensions using Two Retraction Methods: A Comparative Study

Introduction: The goal of Orthodontic treatment is toimprove the patient’s life through enhancement of Dentofacialfunctions and esthetics. Paradigms have started to shift inOrthodontic world since the introduction of mini-implantsin the anchorage armamentarium. So the present study wasundertaken to analyse and compare the amount of Intrusionin maxillary anterior teeth segment using one and twominiscrews, while paying an utmost attention to patientscomfort and esthetics during the treatment.Material and Methods: The sample consisted of 20 subjectswith deep overbite and complete root formation with increasedincisor show. Lateral cephlogram and P.A Cephalogram wererecorded before placement of implant. Sample was furtherdivided in to two groups, Group I (Implant group one implantis placed between maxillary central incisors and two implantsplaced between second premolar and first molar) and GroupII (Implant Group with Power arms, one implant is placedbetween maxillary central incisor and power arms fabricatedon first molar bilaterally). Clinical evaluation of intrusion wasrecorded on every six weeks.Results: The mean intrusion achieved is 0.28mm per 6weeks interval of time in both groups suggesting there is nodifference in amount of intrusion achieved in both groups withp value of 0.697 which is statistically non-significant. Changein Frankfort mandibular plane angle was observed with GroupI and Group II.Conclusion: On the base of study it was concluded thatimplant and power arm is better choice for intrusion inmaxillary anterior segment for correction of deep overbite andcorrection of gummy smile with minimal effect on posteriorsegment

Advance and review: miniscrew-assisted rapid palatal expansion / 中华口腔医学杂志

Rapid palatal expansion (RPE) is commonly used to correct transverse maxillary deficiencies and recognized as a reliable orthopedic procedure in children and adolescents. For adults, however, conventional RPE has been considered rarely successful and can produce undesirable dental effects. Along with the development of digital techniques and mini-implant anchorage, a novel method called miniscrew-assisted RPE (MARPE) has become available for the treatment of maxillary transverse deficiency in older patients recently. In this article, the biomechanical principles and indications of MARPE, the advances in device design, the clinical effects, the matters needing attention and limitations of this method, and the stability after expansion are discussed.

Repositioning of overerupted upper molar for facilitating lower implant placement with miniscrews

@#Loss of the mandibular first molar often leads to the overeruption of the opposing maxillary first molar, resulting in inadequate interocclusal space. In this report, two miniscrews were placed into the buccal and palatal region of the upper first molar to correct the overerupted teeth using power chains. Progress of treatment was evaluated every two weeks for five months. The clinical results showed significant intrusion while maintaining periodontal health, tooth vitality, and root length.

Correlation between tooth size-arch length discrepancy and interradicular distances measured on CBCT and panoramic radiograph: an evaluation for miniscrew insertion

Abstract Introduction: The selection of appropriate sites for miniscrew insertion is critical for clinical success. Objectives: The aim of the present study was to evaluate how interradicular spaces measured on panoramic radiograph compare with Cone-Beam Computed Tomography (CBCT), and how crowding can influence the presence of available space for miniscrew insertion, in order to define a new "safe zones" map. Methods: A total of 80 pre-treatment panoramic radiographs and 80 CBCT scans with corresponding digital models were selected from the archives of the department of Dentistry, Aarhus University. Crowding was measured on digital models, while interradicular spaces mesial to the second molars were measured on panoramic radiographs and CBCTs. For panoramic radiographs, a magnification factor was calculated using tooth widths measured on digital models. Statistical analyses were performed to investigate the correlation between the amount of crowding and the available interradicular space. Visual maps showing the amount of interradicular spaces measured were drawn. Results: The most convenient interradicular spaces are those between the second molar and the first premolar in the mandible, and between the central incisors in the maxilla. However, some spaces were revealed to be influenced by crowding. Conclusions: Calibration of panoramic radiographs is of utmost importance. Generally, panoramic radiographs underestimate the available space. Preliminary assessment of miniscrew insertion feasibility and the related selection of required radiographs can be facilitated using the new "safe zone" maps presented in this article.

Resumo Introdução: a seleção de locais apropriados para a inserção de mini-implantes é crítica para o sucesso clínico. Objetivo: os objetivos do presente estudo foram avaliar as medições de espaços inter-radiculares feitas em radiografias panorâmicas e compará-las com as medições feitas com tomografia computadorizada de feixe cônico (TCFC), além de avaliar como o apinhamento pode influenciar na disponibilidade de espaços para inserção dos mini-implantes, no intuito de definir um novo mapa de "áreas seguras". Métodos: foram selecionadas, nos arquivos do departamento de Ortodontia da Aarhus University, 80 radiografias panorâmicas pré-tratamento e 80 imagens de TCFC com os modelos digitais correspondentes. O apinhamento foi medido nos modelos digitais, enquanto os espaços inter-radiculares mesiais aos segundos molares foram medidos nas radiografias panorâmicas e na TCFC. O fator de magnificação das radiografias panorâmicas foi calculado utilizando-se as larguras dentárias medidas nos modelos digitais. Análises estatísticas foram realizadas para investigar a correlação entre a quantidade de apinhamento e o espaço inter-radicular disponível. Foram desenhados mapas visuais mostrando a quantidade dos espaços inter-radiculares medidos. Resultados: os espaços inter-radiculares mais adequados são aqueles entre o segundo molar e o primeiro pré-molar inferior, e entre os incisivos centrais superiores. Porém, verificou-se que alguns espaços são influenciados pelo apinhamento. Conclusões: A calibração das radiografias panorâmicas é de suma importância, pois, geralmente, as radiografias panorâmicas subestimam o espaço disponível. A avaliação preliminar da viabilidade de inserção dos mini-implantes e a seleção das radiografias necessárias para isso podem ser facilitadas utilizando-se os novos mapas de "áreas seguras" aqui apresentados.

Comprehensive Orthodontic Treatment in a Middle-Aged Patient with Missing Maxillary Left First Premolar: A Case Report

As the adult population continues to increase, orthodontic treatment for adult patients is becoming more common. This case report describes comprehensive orthodontic treatment of a middle-aged patient with closure of the extraction space without prosthetic restoration. A 55-year-old woman with her maxillary left first premolar extracted because of a periodontal problem, wanted to close the space with orthodontic treatment. Since she had generalized crowding and mild skeletal discrepancy, we planned comprehensive orthodontic treatment, including closure of the extraction space by protraction of the left maxillary molars using miniscrews and aesthetic alignment of anterior teeth. The total treatment period was 28 months. As a result of these treatments, the extraction space was successfully closed, good tooth alignment and satisfactory occlusion were achieved.

Advances in studies on distal molar movement with temporary anchorage devices / 中华口腔医学杂志

Crowding and protrusion of the dentition are often the chief complaint of orthodontic patients. For patients with severe crowding or protrusion, orthodontist often improve their profile with premolar extraction treatment. However, for patients with mild crowding and protrusion, orthodontist usually achieve treatment objective using distal molar movement with temporary anchorage devices (TAD). The present article reviewed the advances in the use of TAD in total arch distalization, including therapeutic effect measured in three-dimensions, factors that affected distal movement and the stability of curative effect.

Morphometric analysis of the infrazygomatic crest zone in 84 mini-implants using cone-beam CT / 中华口腔医学杂志

Objective@#To investigate the soft and hard tissue morphology in the infrazygomatic crest zone by observing the cone-beam computed tomography (CBCT) scans in patients with mini-implants.@*Methods@#CBCT scans of 43 patients performed from January 2014 to December 2016 in the Department of Stomatology, Beijing Friendship Hospital, Capital Medical University, with 84 existing mini-implants in the infrazygomatic crest region were collected. The bone thickness and cortical bone thickness were measured in the palatal and buccal side of the mini-implant. The maxillary sinus membrane thickness, sinus septa, reverse fold, and the sinus opening angle were also determined and analyzed in the maxillary posterior region.@*Results@#The bone thicknesses in the buccal and palatal side of the existing mini-implant were 2.5 (1.5, 3.2) and 5.2 (4.0, 6.4) mm, respectively. However, the corresponding cortical bone thicknesses were only 2.1 (1.3, 2.8) and 1.5 (1.0, 1.9) mm, respectively. The prevalences of the septa and the reverse fold were 33% (28/84) and 45% (38/84), respectively. The sinus opening angle was the largest in the mid-coronal plane of the maxillary first molar (71.6°±15.6°). In the coronal plane located at 10 mm mesially, the angle was the smallest (46.1°±18.0°), and in this area, 20% (16/82) of the angle was less than 30°.@*Conclusions@#The outer cortical plate of the infrazygomatic crest along with the cortical plate of sinus floor could be related to the initial stability of mini-implant anchorage. The anatomic variation such as the reverse fold indicated thorough consideration of insertion depth and angle to avoid unexpected sinus injury.

Histomorphometric evaluation of the bone surrounding orthodontic miniscrews according to their adjacent root proximity / 대한치과교정학회지

OBJECTIVE: This study was conducted to perform histomorphometric evaluations of the bone surrounding orthodontic miniscrews according to their proximity to the adjacent tooth roots in the posterior mandible of beagle dogs. METHODS: Four male beagle dogs were used for this study. Six orthodontic miniscrews were placed in the interradicular spaces in the posterior mandible of each dog (n = 24). The implanted miniscrews were classified into no loading, immediate loading, and delayed loading groups according to the loading time. At 6 weeks after screw placement, the animals were sacrificed, and tissue blocks including the miniscrews were harvested for histological examinations. After analysis of the histological sections, the miniscrews were categorized into three additional groups according to the root proximity: high root proximity, low root proximity, and safe distance groups. Differences in the bone–implant contact (BIC, %) among the root proximity groups and loading time groups were determined using statistical analyses. RESULTS: No BIC was observed within the bundle bone invaded by the miniscrew threads. Narrowing of the periodontal ligament space was observed in cases where the miniscrew threads touched the bundle bone. BIC (%) was significantly lower in the high root proximity group than in the low root proximity and safe distance groups. However, BIC (%) showed no significant differences among the loading time groups. CONCLUSIONS: Regardless of the loading time, the stability of an orthodontic miniscrew is decreased if it is in contact with the bundle bone as well as the adjacent tooth root.

The safe zones of posterior miniscrew implant placement in different sagittal skeletal features / 实用口腔医学杂志

Objective:To measure the mesio-distal interradicular space of posterior teeth at different height by CBCT.Methods:60 subjects with skeletal Class Ⅰ,Ⅱ and Ⅲ patterns were included(n =20).From the distal of first premolar to the mesial of second molar,the mesiodistal width at the height of 2,4,6,8 and 10 mm from the alveolar crest were measured and analysed.Results:The interradicular distance was larger than 3 mm within 4-10 mm height in maxilla and in mandible.The maxillary mesiodistal width values measured between the first premolar and second premolar in skeletal Class Ⅰ and Class Ⅱ pattern was greater than that in Class Ⅲ(P ＜0.05) and there was no significant difference in other zones.In the mandible,the values of skeletal Class Ⅲ pattern were greater than those of skeletal Class Ⅰ and Class Ⅱ pattern(P ＜0.05).Conclusion:The suitable interradicular zone is within 4-8 mm to the alveolar crest between the second premolar and first molar for miniscrew implant placement in maxilla,and over 4 mm between the first molar and second molar in mandible.The difference of interradicular spaces in sagittal skeletal features is existed.