Survival rate and stability of surface-treated and non-surface-treated orthodontic mini-implants: a randomized clinical trial

ABSTRACT Objectives: This clinical trial was conducted to evaluate the stability and failure rate of surface-treated orthodontic mini-implants and determine whether they differ from those of non-surface-treated orthodontic mini-implants. Trial Design: Randomized clinical trial with a split-mouth study design. Setting: Department of Orthodontics, SRM Dental College, Chennai. Participants: Patients who required orthodontic mini-implants for anterior retraction in both arches. Methods: Self-drilling, tapered, titanium orthodontic mini-implants with and without surface treatment were placed in each patient following a split-mouth design. The maximum insertion and removal torques were measured for each implant using a digital torque driver. The failure rates were calculated for each type of mini-implant. Results: The mean maximum insertion torque was 17.9 ± 5.6 Ncm for surface-treated mini-implants and 16.4 ± 9.0 Ncm for non-surface-treated mini-implants. The mean maximum removal torque was 8.1 ± 2.9 Ncm for surface-treated mini-implants and 3.3 ± 1.9 Ncm for non-surface-treated mini-implants. Among the failed implants, 71.4% were non-surface-treated mini-implants and 28.6% were surface-treated mini-implants. Conclusion: The insertion torque and failure rate did not differ significantly between the groups, whereas the removal torque was significantly higher in the surface-treated group. Thus, surface treatment using sandblasting and acid etching may improve the secondary stability of self-drilling orthodontic mini-implants. Trial registration: The trial was registered in the Clinical Trials Registry, India (ICMR NIMS). Registration number: CTRI/2019/10/021718

RESUMO Objetivos: Este ensaio clínico foi conduzido para avaliar a estabilidade e a taxa de falha de mini-implantes ortodônticos com superfície tratada, e determinar se elas diferem das dos mini-implantes ortodônticos sem superfície tratada. Desenho do estudo: Ensaio clínico randomizado com desenho de boca dividida. Instituição: Department of Orthodontics, SRM Dental College, Chennai/India. Participantes: Pacientes que necessitavam de mini-implantes ortodônticos para retração anterior em ambas as arcadas. Métodos: Mini-implantes ortodônticos autoperfurantes, cônicos, de titânio com ou sem tratamento de superfície, foram colocados em cada paciente, seguindo um desenho de boca dividida. Os torques máximos de inserção e de remoção foram medidos para cada mini-implante, usando um torquímetro digital. As taxas de falha foram calculadas para cada tipo de mini-implante. Resultados: O valor médio do torque máximo de inserção foi de 17,9 ± 5,6 Ncm para mini-implantes com superfície tratada e 16,4 ± 9,0 Ncm para mini-implantes sem superfície tratada. O valor médio do torque máximo de remoção foi de 8,1 ± 2,9 Ncm para mini-implantes com superfície tratada e 3,3 ± 1,9 Ncm para mini-implantes sem superfície tratada. Entre os implantes que falharam, 71,4% eram mini-implantes sem superfície tratada e 28,6% eram mini-implantes com superfície tratada. Conclusão: O torque de inserção e a taxa de falha não diferiram significativamente entre os grupos; porém, o torque de remoção foi significativamente maior no grupo com superfície tratada. Assim, o tratamento de superfície com jateamento e condicionamento ácido pode melhorar a estabilidade secundária dos mini-implantes ortodônticos autoperfurantes. Registro do estudo: Esse estudo foi registrado no Clinical Trials Registry, Índia (ICMR NIMS). Número de registro: CTRI/2019/10/021718

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.

Correlation between cortical bone thickness at mini-implant insertion sites and age of patient

ABSTRACT Introduction: Orthodontic mini-implants (MI) are a reliable alternative to provide temporary orthodontic anchorage. Prior to miniscrew insertion, the best approach would be to evaluate each possible insertion site and measure the cortical bone thickness, and verify whether it would provide adequate primary stability. Objective: This study aimed to evaluate the difference in cortical bone thickness in areas of mini-implants insertion in patients of different ages, by means of cone beam computed tomography (CBCT). Methods: The sample of this retrospective study was composed of 123 CBCT scans, which were used to measure cortical bone thickness in the buccal and palatal inter-radicular space in the mesial region of the first permanent molars. These measures were compared by using the Student's t-test, ANOVA/Tukey tests, and Linear regression between male and female subjects, from 12 to 30 years old. Results: No significant difference was found in cortical bone thickness between sex, race and sagittal facial patterns. Significantly higher measurement values were observed in patients older than 12 years of age at all sites evaluated. The coefficient β at the adjusted linear regression analysis showed that at each increment in age, mean cortical thickness values increased by 0.06mm in the mandible, 0.03mm in the buccal region and 0.02mm in the palatal region of the maxilla. Conclusions: The increase in cortical bone thickness was positively associated with age; that is, the more advanced the patient's age was, the less chance there was of failure due to primary stability.

RESUMO Introdução: Os mini-implantes ortodônticos (MI) são uma alternativa confiável para fornecer ancoragem esquelética temporária. Antes da inserção do mini-implante, a melhor abordagem seria avaliar cada local de inserção possível, medir a espessura do osso cortical e verificar se proporcionaria uma adequada estabilidade primária. Objetivo: O presente estudo teve como objetivo avaliar a diferença na espessura do osso cortical em áreas de inserção dos mini-implantes em pacientes de diferentes idades, por meio da tomografia computadorizada de feixe cônico. Métodos: A amostra desse estudo retrospectivo foi composta por 123 tomografias computadorizadas de feixe cônico, que foram utilizadas para medir a espessura do osso cortical nos espaços inter-radiculares vestibular e palatino na região mesial dos primeiros molares permanentes. Essas medidas foram comparadas por meio dos testes t de Student, ANOVA/Tukey e regressão linear entre os sexos masculino e feminino, de 12 a 30 anos. Resultados: Não houve diferença estatisticamente significativa na espessura cortical, quando comparados sexo, cor da pele e padrão facial sagital. Foram verificadas medidas significativamente maiores em pacientes com idade superior a 12 anos em todos os sítios avaliados. O coeficiente β da análise de regressão linear ajustada mostrou que, a cada incremento da idade, os valores médios da espessura cortical aumentaram 0,06 mm na mandíbula, 0,03 mm na região vestibular e 0,02 mm na região palatina da maxila. Conclusão: O aumento da espessura do osso cortical teve associação positiva com a idade, ou seja, quanto mais avançada a idade do paciente, menor a chance de falha, devido à estabilidade primária.

Research progress on the three-dimensional finite element analysis of bite opening / 口腔疾病防治

@#Deep bite is a common clinical malocclusion that has a great impact on patients’ facial aesthetics and oral function. Bite opening is the key step in the treatment of deep bite, playing a decisive role in the development of mandible and the progress of orthodontic treatment. Torque and tip control during the correction of deep bites is a hot topic in orthodontics. The three-dimensional finite element method can accurately simulate clinical processes and conduct dynamic stress analysis, which provides the basis of the biomechanical mechanism. This paper reviewed the finite element analysis of various orthodontic systems for bite opening to provide a reference for clinical application. The emergence of mini-implants provided a new idea for anchorage control in bite opening. Finite element studies found that high-positioned mini-implants are beneficial for bodily tooth intrusion and proposed the ideal position for force application. For the finite element simulation of the reverse curve archwire, it was found that the intrusion and inclination of the anterior teeth increased with the curve depth of the archwire. The application of clear aligners has also been flourishing, but these forces are still difficult to effectively control. Finite element studies on their attachment design and corresponding tooth movement may be helpful to open the bite quickly and effectively. However, the existing studies still have modeling limitations. The structural simplification, linearization and nonstandard parameter definition of the model reduce model accuracy. Additionally, the existing research mostly focused on initial tooth movement, and studies on long-term tooth movement after bone remodeling are lacking. These studies are needed in the future.

Changes in canine position during maxillary molar distalization with mini-implant and CD appliance: an in vitro study / 口腔疾病防治

Objective@#To investigate changes in the three⁃dimensional position of the maxillary canine during the distal movement of the maxillary first molar by a mini⁃implant combined with a CD appliance.@*Methods@#Ten typodont models of class II malocclusion were selected, and one side was randomly chosen as the experimental group. The CD ap⁃ pliance was bonded to the maxillary canine and first molar of the experimental group, and 1.2 mm stainless steel wire was bent as the anchorage, which was fixed on the model to simulate mini⁃implants implanted in the zygomatic alveolar ridge. Then, 180 g orthodontic force was applied to the canine of the experimental group; the other side was recognized as the control group and was not used for strengthening. Six mini⁃implants were implanted in different parts of the mod⁃ el and used as a reference before and after the experiment. The models were placed in an incubator and heated at 56 ℃ in a water bath for 2 min. The models were scanned before and after thermostatic water bath treatment with a 3⁃shape scanner. Then, the digital models were overlapped through the reference points, and the positions of the canines and first molars were measured before and after the experiment.@*Results@#The sagittal movement distance of the first molar in the experimental group was ( 0.25 ± 0.33) mm, and the vertical movement distance was (0.25 ± 0.28 )mm, which was significantly different from the control group (P < 0.05), while the transverse change was not significantly different (P > 0.05). There was no significant difference in the root position of the first molar in the experimental group (P > 0.05). The lateral and vertical displacement distances of the maxillary canine crown in the experimental group were (4.03 ± 2.11) mm and (1.86 ± 1.01) mm, respectively, which were significantly different from those in the control group (P < 0.001), while the sagittal changes showed no significant differences (P > 0.05). In the experimental group, there was no significant difference in the position of the apex of the maxillary cusp (P > 0.05).@*Conclusion@#Our in vitro study showed that the maxillary canines inclined buccally accompanied by a small amount of intrusion during molar distaliza⁃ tion by a mini⁃implant combined with a CD appliance.

Three-dimensional finite element analysis of mini implants supported mandibular overdentures / 中国组织工程研究

BACKGROUND: Overdenture supported by two to four implants located in the mandibular mental foramen area has been widely used in edentulous patients. However, in patients with severe mandibular resorption, it is a challenging to insert conventional implants. Mini-implants are a better choice in these cases. OBJECTIVE: To compare and analyze the biomechanical characteristics of conventional and mini-implants supported mandibular complete overdenture and to reveal the influence of different implant repair methods on implants and its surrounding tissues. METHODS: The cone beam CT data of a healthy patient scheduled to receive complete edentulous implant supported overdenture was obtained. CT data of the patient, implant and attachment data were imported into the software to create four models: 2 normal implants, 4 normal implants, 4 mini implants, and 5 mini implants supported mandibular overdentures respectively. The overdenture was bilaterally subjected to a vertical load of 150 N. The displacement and stress of implants and the stress of bone were compared. RESULTS AND CONCLUSION: For all models, the lowest and highest maximum values of stress in bone were obtained from 4 normal implant model (2.71 MPa) and 4 mini implant model (7.93 MPa). The lowest and highest maximum values of displacement in implant were obtained from 4 normal implant model (1.37 µm) and 2 normal implant model (1.57 µm). Moreover, the lowest and highest maximum values of stress in implant were demonstrated from 4 normal implant model (12.90 MPa) and 4 mini implant model (22.17 MPa). The biomechanical values of mini implant models were higher than those of conventional models. The biomechanical values of all models were below the critical limits. The distribution was more homogenous and the maximum values of displacement in the implant, stress in implant and stress in bone were reduced as the number of implants increased. Three-dimensional finite element analysis revealed that mandibular overdenture supported by four or five mini implants is a reliable treatment option.

Stability of the anterior arm of three different Hyrax hybrid expanders: an in vitro study

ABSTRACT Introduction: The force applied to the teeth by fixed orthopaedic expanders has previously been studied, but not the force applied to the orthodontic mini-implant (OMI) used to expand the maxilla with Hyrax hybrid expanders (HHE). Objective: The aim of this article was to evaluate the clinical safety of the components (OMI, abutment and double wire arms) of three different force-transmitting systems (FTS) for conducting orthopaedic maxillary expansion: Jeil Medical & Tiger Dental™, Microdent™ and Ortholox™. Methods: For the realization of this in vitro study of the resistance to mechanical load, three different abutment types (bonded, screwed on, and coupling) and three different OMIs' diameters (Jeil™ 2.5 mm, Microdent™ 1.6 mm and Ortholox™ 2.2 mm) were used. Ten tests for each of these three FTS were carried out in a static lateral load in artificial bone blocks (Sawbones™) by a Galdabini universal testing machine, then comparing its performance. Comparisons of loads, deformations and fractures were carried out by means of radiographs of FTS components in each case. Results: At 1- mm load and within the elastic deformation, FTS values ranged from 67 ± 13 N to 183 ± 48 N. Under great deformations, Jeil & Tiger™ was the one who withstood the greatest loads, with an average 378 ± 22 N; followed by Microdent™, with 201 ± 18 N, and Ortholox™, with 103 ± 10 N. At 3 mm load, the OMIs shaft bends and deforms when the diameter is smaller than 2.5 mm. The abutment fixation is crucial to transmit forces and moments. Conclusions: The present study shows the importance of a rigid design of the different components of HHEs, and also that HHEs would be suitable for maxillary expansion in adolescents and young adults, since its mean expansion forces exceed 120N. Furthermore, early abutment detachment or smaller mini-implants diameter would only be appropriate for children.

RESUMO Introdução: a força aplicada sobre os dentes por expansores ortopédicos fixos já foi estudada antes, mas não a força aplicada sobre os mini-implantes ortodônticos (MIOs) usados para expandir a maxila com expansores do tipo Hyrax híbrido (EHH). Objetivo: o objetivo desse artigo foi avaliar a segurança clínica dos componentes (MIO, abutment de fixação, e braços de fio duplo) de três sistemas de transmissão de força (STF) usados para expansão ortopédica da maxila: Jeil Medical & Tiger Dental™, Microdent ™ e Ortholox ™. Métodos: para realizar esse estudo in vitro sobre a resistência à carga mecânica, foram usadas três tipos de sistema de fixação (colado, aparafusado e coupling) e MIOs de três diâmetros diferentes (Jeil™ 2,5 mm; Microdent™ 1,6 mm e Ortholox™ 2,2 mm), com suas respectivas mecânicas de STF. Foram realizados 10 testes para cada STF, usando uma carga lateral estática em blocos de osso artificial (Sawbones™), com uma máquina universal de testes e, depois, comparou-se, por meio de radiografias, os desempenhos, levando-se em consideração as cargas, deformações e fraturas dos componentes de cada STF. Resultados: com a carga a 1 mm e sem exceder o limite de deformação elástica, os valores dos STFs variaram de 67 ± 13 N a 183 ± 48 N. Sob deformações maiores, o sistema Jeil & Tiger™ foi o que apresentou maior resistência às cargas elevadas, com valor de 378 ± 22 N; seguido pelo Microdent™, com 201 ± 18 N, e Ortholox™, com 103 ± 10 N. Com a carga a 3 mm, o eixo do MIO se dobrou e deformou quando seu diâmetro era menor que 2,5 mm. O abutment de fixação é crucial para a transmissão das forças e momentos. Conclusões: o presente estudo evidenciou a importância da rigidez no design dos diferentes componentes dos STFs dos EHH. Também revelou que eles são adequados para a expansão da maxila em adolescentes e adultos jovens, pois as forças de expansão, em média, excederam os 120N. Além disso, a desconexão precoce do abutment ou o uso de mini-implantes de menor diâmetro no design do STF seriam apropriados apenas em crianças.

Vertical Play of Straight Wire Appliance Aids Correction of Gummy Smile and Bimaxillary Incisor Proclination with Mini Implant Anchorage

@#This report aimed to describe an effective biomechanics to control the upper incisors inclination during the correction of gummy smile with bimaxillary proclinations. A 14-year-old female presented with a Class II division I incisor relationship complicated with bimaxillary proclination on a Class 2 skeletal base. The lips were incompetent, showing 7 mm of upper incisors at rest and 5mm maxillary gingival display on smiling with normal upper lip length. Treatment involved extraction of all first permanent premolars followed by upper and lower fixed appliances. Intrusion of the upper incisors with controlled labial crown torque was accomplished with mini-implant anchorage placed bilaterally on the infrazygomatic crests with the retraction forces above the centre of resistance using 0.019x0.025-in stainless steel archwire in 0.022-in slot. The 0.019x0.025-in stainless steel archwire in 0.022-in slot provided the vertical play to favour lingual crown tipping despite having forces above the centre of resistance for concurrent anterior segment intrusion.

Cone-beam computed tomography-based diagnosis and treatment simulation for a patient with a protrusive profile and a gummy smile / 대한치과교정학회지

For patients with bimaxillary protrusion, significant retraction and intrusion of the anterior teeth are sometimes essential to improve the facial profile. However, severe root resorption of the maxillary incisors occasionally occurs after treatment because of various factors. For instance, it has been reported that approximation or invasion of the incisive canal by the anterior tooth roots during retraction may cause apical root damage. Thus, determination of the position of the maxillary incisors is key for orthodontic diagnosis and treatment planning in such cases. Cone-beam computed tomography (CBCT) may be useful for simulating the post-treatment position of the maxillary incisors and surrounding structures in order to ensure safe teeth movement. Here, we present a case of Class II malocclusion with bimaxillary protrusion, wherein apical root damage due to treatment was minimized by pretreatment evaluation of the anatomical structures and simulation of the maxillary central incisor movement using CBCT. Considerable retraction and intrusion of the maxillary incisors, which resulted in a significant improvement in the facial profile and smile, were achieved without severe root resorption. Our findings suggest that CBCT-based diagnosis and treatment simulation may facilitate safe and dynamic orthodontic tooth movement, particularly in patients requiring maximum anterior tooth retraction.

Autotransplantation: A biological treatment alternative for a patient after traumatic dental injury / 대한치과교정학회지

Traumatic dental injury is considered a public dental health problem because of a high childhood incidence, high treatment costs, and prolonged treatment time. Although management guidelines for traumatized teeth have been outlined, tooth loss following trauma is occasionally unavoidable. Here, we describe the successful interdisciplinary management of a traumatized central incisor in an 11-year old boy that was extracted because of a poor prognosis and restored by the autotransplantation of an immature donor tooth into the site. The patient underwent orthodontic treatment in order to close the donor site space and bring the autotransplanted tooth to an ideal position. Postorthodontic treatment radiographs and photographs revealed an esthetic and functional natural tooth replacing the lost tooth. The findings from this case suggest that autotransplantation offers unique advantages as a treatment modality for the restoration of missing teeth, particularly in growing children.

Average interradicular sites for miniscrew insertion: should dental crowding be considered?

ABSTRACT Objective: To define a map of interradicular spaces where miniscrew can be likely placed at a level covered by attached gingiva, and to assess if a correlation between crowding and availability of space exists. Methods: Panoramic radiographs and digital models of 40 patients were selected according to the inclusion criteria. Interradicular spaces were measured on panoramic radiographs, while tooth size-arch length discrepancy was assessed on digital models. Statistical analysis was performed to evaluate if interradicular spaces are influenced by the presence of crowding. Results: In the mandible, the most convenient sites for miniscrew insertion were in the spaces comprised between second molars and first premolars; in the maxilla, between first molars and second premolars as well as between canines and lateral incisors and between the two central incisors. The interradicular spaces between the maxillary canines and lateral incisors, and between mandibular first and second premolars revealed to be influenced by the presence of dental crowding. Conclusions: The average interradicular sites map hereby proposed can be used as a general guide for miniscrew insertion at the very beginning of orthodontic treatment planning. Then, the clinician should consider the amount of crowding: if this is large, the actual interradicular space in some areas might be significantly different from what reported on average. Individualized radiographs for every patient are still recommended.

RESUMO Objetivo: elaborar um mapa dos espaços inter-radiculares nos quais os mini-implantes podem ser inseridos, em um nível coberto por gengiva inserida; e avaliar se existe correlação entre o apinhamento dentário e a disponibilidade de espaços. Métodos: radiografias panorâmicas e modelos digitais de 40 pacientes foram selecionados seguindo critérios de inclusão. Os espaços inter-radiculares foram medidos nas radiografias panorâmicas, enquanto a discrepância de modelo foi avaliada nos modelos digitais. Realizou-se, então, uma análise estatística para avaliar se os espaços inter-radiculares foram influenciados pela presença do apinhamento dentário. Resultados: na mandíbula, os locais mais adequados para a inserção dos mini-implantes foram os espaços compreendidos entre os segundos molares e primeiros pré-molares; na maxila, entre os primeiros molares e segundos pré-molares, bem como entre caninos e incisivos laterais, e entre os dois incisivos centrais. Os espaços inter-radiculares entre os caninos e incisivos laterais superiores e entre o primeiro e o segundo pré-molares inferiores mostraram-se influenciados pela presença do apinhamento dentário. Conclusões: o mapa dos espaços inter-radiculares mais adequados aqui proposto pode ser adotado como um guia geral para a inserção de mini-implantes, e pode ser usado logo ao início do planejamento do tratamento ortodôntico. Em seguida, o clínico deve levar em consideração a quantidade de apinhamento: caso esse seja grande, o real espaço inter-radicular, em algumas áreas, poderá ser significativamente diferente da média aqui relatada. Assim, recomenda-se que sempre sejam feitas radiografias individualizadas para cada paciente.

Fracture strength of orthodontic mini-implants

ABSTRACT Objective: This study aimed at evaluating the design and dimensions of five different brands of orthodontic mini-implants, as well as their influence on torsional fracture strength. Methods: Fifty mini-implants were divided into five groups corresponding to different manufactures (DEN, RMO, CON, NEO, SIN). Twenty-five mini-implants were subjected to fracture test by torsion in the neck and the tip, through arbors attached to a Universal Mechanical Testing Machine. The other 25 mini-implants were subjected to insertion torque test into blocks of pork ribs using a torquimeter and contra-angle handpiece mounted in a surgical motor. The shape of the active tip of the mini-implants was evaluated under microscopy. The non-parametric Friedman test and Snedecor's F in analysis of variance (ANOVA) were used to evaluate the differences between groups. Results: The fracture torque of the neck ranged from 23.45 N.cm (DEN) to 34.82 N.cm (SIN), and of the tip ranged from 9.35 N.cm (CON) to 24.36 N.cm (NEO). Insertion torque values ranged from 6.6 N.cm (RMO) to 10.2 N.cm (NEO). The characteristics that most influenced the results were outer diameter, inner diameter, the ratio between internal and external diameters, and the existence of milling in the apical region of the mini-implant. Conclusions: The fracture torques were different for both the neck and the tip of the five types evaluated. NEO and SIN mini-implants showed the highest resistance to fracture of the neck and tip. The fracture torques of both tip and neck were higher than the torque required to insert mini-implants.

RESUMO Objetivo: o objetivo do presente estudo foi avaliar o desenho e as medidas de cinco marcas diferentes de mini-implantes ortodônticos, e sua influência na resistência à fratura em torção. Métodos: cinquenta mini-implantes foram divididos em cinco grupos, correspondentes a diferentes fabricantes (DEN, Dentaurum; RMO, Rocky Mountain Orthodontics; CON, Conexão; NEO, Neodent; SIN, Sistema de Implantes Nacional). Vinte e cinco mini-implantes foram submetidos ao teste de fratura por torção no pescoço e na ponta, com mandris fixados a uma máquina universal de testes mecânicos. Os outros 25 mini-implantes foram submetidos ao teste de torque de inserção em blocos de costelas suínas, utilizando-se um torquímetro e um contra-ângulo montado em motor cirúrgico. O formato da ponta ativa dos mini-implantes foi avaliado por microscopia. O teste não-paramétrico de Friedman e o teste F de Snedecor na análise de variância (ANOVA) foram utilizados para avaliar as diferenças entre os grupos. Resultados: o torque de fratura do pescoço variou de 23,45 N.cm (DEN) a 34,82 N.cm (SIN); e o da ponta, entre 9,35 N.cm (CON) e 24,36 N.cm (NEO). O valor do torque de inserção variou de 6,6 N.cm (RMO) a 10,2 N.cm (NEO). As características que mais influenciaram os resultados foram: diâmetro externo, diâmetro interno, razão entre o diâmetro interno e o externo, e a presença de fresagem na região apical do mini-implante. Conclusões: os torques de fratura foram diferentes entre os cinco tipos avaliados, tanto no pescoço quanto na ponta. Os mini-implantes NEO e SIN foram os mais resistentes à fratura do pescoço e da ponta. Os torques de fratura tanto na ponta quanto no pescoço foram maiores do que o torque necessário para a inserção dos mini-implantes.

Spiral CT evaluation of the alveolar cortical bone mineral density and bone cortex thickness of teenagers and adults / 实用口腔医学杂志

Objective:To compare the alveolar cortical bone density and thickness of jaw bones between teenagers (12-18 years of age) and adults(19-48 years of age).Methods:Spiral computed tomographic images of 60 cases were obtained from the subjects with the ages of 12 to 48 years(27 Males and 33 females,35 teenagers and 25 adults).Buccal cortical bone thickness and density in Hounsfield units were measured at 12 interradicular sites and to a depth of 14 mm.Results:The alveolar cortical bone thicknesses and densities of the jaw bones significantly increased from the crest to base of alveolar crest.The average cortical bone thicknesses rangedfrom 1.0 to 1.5 mm in the anterior part of the jaw bones,1.1 to 1.8 mm in maxillary posterior area and 1.5 to 2.8 mm in the mandible posterior areas.The cortical bone thickness and density were greater in the mandible than in the maxilla(P ＜ 0.05).The thickness values did not show difference between males and females,between adolescents and adults.Higher values of bone density were found in the adults than in the teenagers(P ＜0.05).The highest bone density in the mandible posterior area of adults was observed,and the lowest bone density in the maxillary posterior area of adolescents.Conclusion:Alveolar cortical bone density of adolescents is lower than that of adults,especially in the maxilla posterior region.

Histomophometrical evaluation of biodegradable mini-implants for orthodontic anchorage in the mandibu-lar of beagle dogs / 实用医学杂志

Objective To investigate the biocompatibility and biodegradability of mini-implants of PLA-based composites in experimental animals by histomorphometry, and to study its clinical application in orthodontic treatment. Methods Six adult male Beagle dogs were randomly divided into 3 groups, a total of 72 mini-implants were implanted to the mandibular. Two Beagle dogs were sacrificed at 2 months、4 months and 6 months after surgery. Animals were intramuscularly injected with tetracycline on 14 and 4 days before sacrifice. Mandibular specimens and the surfaces of mini-implants were examined with Cone beam CT, CBCT and Scanning Electronic Microscopy and SEM respectively. Histopathologocal changes were observed with toluidine blue staining and HE staining. Results The results of CBCT assay showed that the mini-implants were gradually radiopacity with the extension of time. SEM assay showed that the morphology of mini-implants surface was significantly changed;micro-implants degradation occured gradually.New bone formation was observed around the micro-implants within 10 days.Toluidine blue staining showed the formation of new bone around the mini-implants. However, the inflamma-tion around the implants was not observed. Conclusion The biocompatibility of biodegradable mini-implant is good. This mini-implant is biodegradable in vivo and can promote the formation of the surrounding bone tissue.

Mandibular implant supported overdentures with two different mini-implant systems: A case report / 대한치과보철학회지

This case report describes the treatment of two fully edentulous patients with mini-implant overdentures using different implant systems on narrow mandibular alveolar bone ridge. They were complaining about discomfort and pain wearing mandibular conventional complete dentures caused by insufficient retention. Each patient received four mini-implants in the interforaminal area of the mandible using the non-submerged flapless surgical approach. One-body type implant (Slimline, Dentium, Seoul, Korea) was used for a patient and loaded immediately after surgery. Metal housings of O-ring were attached by direct technique. For the other patient, two-piece type implant (LODI, Zest Anchors, Escondido, CA, USA) was used and impressions were made for attachment connection of the Locator's metal housings after 8 weeks of surgery. Within this case report, mandibular mini-implant overdentures using different implant systems showed improvement of patient satisfaction with favorable peri-implant tissue response 6 months after attachment connection. However, long-term follow-up is needed for further evaluation.

Finite element analysis of maxillary incisor displacement during en-masse retraction according to orthodontic mini-implant position / 대한치과교정학회지

OBJECTIVE: Orthodontic mini-implants (OMI) generate various horizontal and vertical force vectors and moments according to their insertion positions. This study aimed to help select ideal biomechanics during maxillary incisor retraction by varying the length in the anterior retraction hook (ARH) and OMI position. METHODS: Two extraction models were constructed to analyze the three-dimentional finite element: a first premolar extraction model (Model 1, M1) and a residual 1-mm space post-extraction model (Model 2, M2). The OMI position was set at a height of 8 mm from the arch wire between the second maxillary premolar and the first molar (low OMI traction) or at a 12-mm height in the mesial second maxillary premolar (high OMI traction). Retraction force vectors of 200 g from the ARH (-1, +1, +3, and +6 mm) at low or high OMI traction were resolved into X-, Y-, and Z-axis components. RESULTS: In M1 (low and high OMI traction) and M2 (low OMI traction), the maxillary incisor tip was extruded, but the apex was intruded, and the occlusal plane was rotated clockwise. Significant intrusion and counter-clockwise rotation in the occlusal plane were observed under high OMI traction and -1 mm ARH in M2. CONCLUSIONS: This study observed orthodontic tooth movement according to the OMI position and ARH height, and M2 under high OMI traction with short ARH showed retraction with maxillary incisor intrusion.

Bone cutting capacity and osseointegration of surface-treated orthodontic mini-implants / 대한치과교정학회지

OBJECTIVE: The objective of the study was to evaluate the practicality and the validity of different surface treatments of self-drilling orthodontic mini-implants (OMIs) by comparing bone cutting capacity and osseointegration. METHODS: Self-drilling OMIs were surface-treated in three ways: Acid etched (Etched), resorbable blasting media (RBM), partially resorbabla balsting media (Hybrid). We compared the bone cutting capacity by measuring insertion depths into artificial bone (polyurethane foam). To compare osseointegration, OMIs were placed in the tibia of 25 rabbits and the removal torque value was measured at 1, 2, 4, and 8 weeks after placement. The specimens were analyzed by optical microscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). RESULTS: The bone cutting capacity of the etched and hybrid group was lower than the machined (control) group, and was most inhibited in the RBM group (p < 0.05). At 4 weeks, the removal torque in the machined group was significantly decreased (p < 0.05), but was increased in the etched group (p < 0.05). In the hybrid group, the removal torque significantly increased at 2 weeks, and was the highest among all measured values at 8 weeks (p < 0.05). The infiltration of bone-like tissue surface was evaluated by SEM, and calcium and phosphorus were detected via EDS only in the hybrid group. CONCLUSIONS: Partial RBM surface treatment (hybrid type in this study) produced the most stable self-drilling OMIs, without a corresponding reduction in bone cutting capacity.

Three-dimensional evaluation of tooth movement in Class II malocclusions treated without extraction by orthodontic mini-implant anchorage / 대한치과교정학회지

OBJECTIVE: The aim of this study was to analyze tooth movement and arch width changes in maxillary dentition following nonextraction treatment with orthodontic mini-implant (OMI) anchorage in Class II division 1 malocclusions. METHODS: Seventeen adult patients diagnosed with Angle's Class II division 1 malocclusion were treated by nonextraction with OMIs as anchorage for distalization of whole maxillary dentition. Three-dimensional virtual maxillary models were superimposed with the best-fit method at the pretreatment and post-treatment stages. Linear, angular, and arch width variables were measured using Rapidform 2006 software, and analyzed by the paired t-test. RESULTS: All maxillary teeth showed statistically significant movement posteriorly (p 0.05) and the intercanine, interfirst premolar, intersecond premolar, and interfirst molar widths increased significantly (2.2 mm, p < 0.01; 2.2 mm, p < 0.05; 1.9 mm, p < 0.01; 2.0 mm, p < 0.01; respectively). CONCLUSIONS: Nonextraction treatment with OMI anchorage for Class II division 1 malocclusions could retract the whole maxillary dentition to achieve a Class I canine and molar relationship without a change in the vertical position of the teeth; however, the second molars were significantly extruded. Simultaneously, the maxillary arch was shown to be expanded with distal-in rotation of the molars.

Analysis of midpalatal miniscrew-assisted maxillary molar distalization patterns with simultaneous use of fixed appliances: A preliminary study / 대한치과교정학회지

Skeletal anchorage-assisted upper molar distalization has become one of the standard treatment modalities for the correction of Class II malocclusion. The purpose of this study was to analyze maxillary molar movement patterns according to appliance design, with the simultaneous use of buccal fixed orthodontic appliances. The authors devised two distinct types of midpalatal miniscrew-assisted maxillary molar distalizers, a lingual arch type and a pendulum type. Fourteen patients treated with one of the two types of distalizers were enrolled in the study, and the patterns of tooth movement associated with each type were compared. Pre- and post-treatment lateral cephalograms were analyzed. The lingual arch type was associated with relatively bodily upper molar distalization, while the pendulum type was associated with distal tipping with intrusion of the upper molar. Clinicians should be aware of the expected tooth movement associated with each appliance design. Further well designed studies with larger sample sizes are required.

Application of one-part form mini-implant in immediately and delayed repair of edentulous space / 局解手术学杂志

Objective To analyze the effect of one-part form mini-implant in treatment of immediately and delayed repair of edentulous space. Methods Retrospectively analyzed 80 cases of edentulous space patients in our hospital from Jan. 2009 to Jan. 2011, and divided them into the immediately repair group ( observation group) and the delayed repair group ( control group) according to time of edentulous space repair. Patients of the two groups were given permanent PFM 3 months later, and regular clinical and X-ray examinations were made to evaluated clinical efficacy and complications of the two groups. Results The score of ISQ of the observation group was higher than that in the control group with significant difference (P <0. 05); and the postoperative complications of the observation group was significantly decreased compared to the control group with a significant difference (P <0. 05). Conclusion Mini-implant used in immediately repair in edentulous space can remove pain in a short time with less postoperative complications, it has more advantages than delayed repair of edentulous space.