Safe zones of the maxillary alveolar bone in Down syndrome for orthodontic miniscrew placement assessed with cone-beam computed tomography.

The aim of this study was to quantify the available maxillary alveolar bone in a group of individuals with Down syndrome (DS) to determine the best areas for orthodontic miniscrew placement. The study group consisted of 40 patients with DS aged 12-30 years. We also selected an age and sex-matched control group. All measurements were performed on cross-sectional images obtained with cone-beam computed tomography. The selected areas of interest were the 4 interradicular spaces between the distal wall of the canine and the mesial wall of the second molar, in both maxillary quadrants. We measured the vestibular-palatine (VP) and mesiodistal (MD) dimensions to depths of 3, 6 and 9 mm from the alveolar ridge. We also measured the bone density in the same interradicular spaces of interest to 6 mm of depth from the alveolar crest. VP measurements were longer in the more posterior sectors and as the distance from the alveolar ridge increased. MD measurements also increased progressively as the distance from the alveolar ridge increased. In general, both the VP and MD measurements in the DS group were similar among the male and female participants. As age increased, the MD distance increased, while the VP distance decreased. The VP distance was ≥6 mm in at least 75% of the DS group in practically all assessed interdental spaces. The MD distance was ≥2 mm in at least 75% of the DS group only between the first and second molar, to 9 mm of depth from the alveolar ridge. The safe area for inserting orthodontic miniscrews in DS patients is restricted to the most posterior and deepest area of the maxillary alveolar bone.

Miniscrew biomechanics: Guidelines for the use of rigid indirect anchorage mechanics.

Indirect anchorage is an established form of anchorage provided by orthodontic miniscrews. Although there are different ways to set up the mechanics, rigid indirect anchorage offers the greatest biomechanical versatility but is more difficult to install than conventional, nonrigid indirect anchorage or direct anchorage. The purpose of this article was to introduce readers to the concept of rigid indirect anchorage and provide guidelines as to its use.

Factors Affecting the Clinical Success Rate of Miniscrew Implants for Orthodontic Treatment.

PURPOSE: The purpose of this study was to evaluate the various factors that influence the success rate of miniscrew implants used as orthodontic anchorage. MATERIALS AND METHODS: Potential confounding variables examined were sex, age, vertical (FMA) and sagittal (ANB) skeletal facial pattern, site of placement (labial and buccal, palatal, and retromandibular triangle), arch of placement (maxilla and mandible), placement soft tissue type, oral hygiene, diameter and length of miniscrew implants, insertion method (predrilled or drill-free), angle of placement, onset and strength of force application, and clinical purpose. The correlations between success rate and overall variables were investigated by logistic regression analysis, and the effect of each variable on the success rate was utilized by variance analysis. RESULTS: One hundred fourteen patients were included with a total of 253 miniscrew implants. The overall success rate was 88.54% with an average loading period of 9.5 months in successful cases. Age, oral hygiene, vertical skeletal facial pattern (FMA), and general placement sites (maxillary and mandibular) presented significant differences in success rates both by logistic regression analysis and variance analysis (P < .05). CONCLUSION: To minimize the failure of miniscrew implants, proper oral hygiene instruction and effective supervision should be given for patients, especially young (< 12 years) high-angle patients with miniscrew implants placed in the mandible.

Measuring bone density at orthodontic miniscrew implantation sites using microcomputed tomography.

PURPOSE: This study was performed to determine the accuracy of measurements of bone mineral density (BMD) and cortical bone thickness (CBT) at miniscrew implantation sites in small animals and to verify the usefulness of in vivo microcomputed tomography (micro-CT). MATERIALS AND METHODS: Rat femurs were scanned before and after placing miniscrews using in vivo micro-CT. The images were superimposed using a subtraction method with bone volume measurement software. At each screw site, the total BMD was calculated as the average BMD of a cylinder 1.6 mm in diameter and 2.0 mm in depth, while the cortical BMD was the average BMD of a cylinder 1.6 mm in diameter and 1.0 mm in depth. CBT was measured three times on transaxial images of the rat femurs, and the average value was used. All miniscrews were placed using the maximum torque, verified with a digital torque tester. To verify the usefulness and accuracy of in vivo micro-CT, CBT on micro-CT images was compared with that measured on histologic sections. RESULTS: Significant correlations were observed between placement torque and cortical BMD (R = 0.572), total BMD (R = 0.732), and CBT (R = 0.788). There was a significant correlation between CBT measured via field-emission scanning electron microscopy images and CBT measured with in vivo micro-CT (R = 0.974). CONCLUSIONS: The BMD over a narrow range can be measured accurately in small animals with high reproducibility of the trabecular structure using a combination of high-resolution in vivo micro-CT and image superimposition using a three-dimensional subtraction method.

Revisiting the stability of mini-implants used for orthodontic anchorage.

BACKGROUND/PURPOSE: The aim of this study is to comprehensively analyze the potential factors affecting the failure rates of three types of mini-implants used for orthodontic anchorage. METHODS: Data were collected on 727 mini-implants (miniplates, predrilled titanium miniscrews, and self-drilling stainless steel miniscrews) in 220 patients. The factors related to mini-implant failure were investigated using a Chi-square test for univariate analysis and a generalized estimating equation model for multivariate analysis. RESULTS: The failure rate for miniplates was significantly lower than for miniscrews. All types of mini-implants, especially the self-drilling stainless steel miniscrews, showed decreased stability if the previous implantation had failed. The stability of predrilled titanium miniscrews and self-drilling stainless steel miniscrews were comparable at the first implantation. However, the failure rate of stainless steel miniscrews increased at the second implantation. The univariate analysis showed that the following variables had a significant influence on the failure rates of mini-implants: age of patient, type of mini-implant, site of implantation, and characteristics of the soft tissue around the mini-implants. The generalized estimating equation analysis revealed that mini-implants with miniscrews used in patients younger than 35 years, subjected to orthodontic loading after 30 days and implanted on the alveolar bone ridge, have a significantly higher risk of failure. CONCLUSION: This study revealed that once the dental surgeon becomes familiar with the procedure, the stability of orthodontic mini-implants depends on the type of mini-implant, age of the patient, implantation site, and the healing time of the mini-implant. Miniplates are a more feasible anchorage system when miniscrews fail repeatedly.

Taxa de sobrevivência clínica de dispositivos temporários de ancoragem (DTAs) / Clinical survival rate of temporary anchorage devices (TADS)

Introdução: uma das maiores preocupações em relação aos tratamentos ortodônticos refere- se ao tipo de ancoragem a ser utilizada. Na busca por um dispositivo temporário de ancoragem que seja eficiente e versátil para o tratamento ortodôntico, descobriu-se que os parafusos para fixação cirúrgica — embora pequenos — possuíam boa resistência para suportar a maioria das forças ortodônticas. Assim, os dispositivos de ancoragem temporária (DTAs) ganharam espaço e credibilidade no campo ortodôntico graças às inúmeras vantagens apresentadas. Objetivo: verificar a taxa de sobrevivência dos DTAs. Métodos: foram analisados 26 pacientes, com idade entre 8 e 42 anos, submetidos a tratamento ortodôntico, nos quais foram implantados 39 dispositivos com diferentes finalidades. Resultados: dos dispositivos inseridos, 32 obtiveram sucesso e 7 fracassaram, resultando em 82% de eficácia. Nossos resultados estão de acordo com a literatura consultada, mostrando sobrevivência satisfatória desses dispositivos, independentemente do profissional que o instalou, da técnica cirúrgica usada e do propósito para o qual foi instalado. Conclusão: eventuais perdas ou insucessos podem estar relacionados a inúmeros fatores, como os procedimentos cirúrgicos de implantação, os cuidados tomados pelo cirurgião-dentista na colocação correta e na aplicação de força ortodôntica, a escolha correta do dispositivo a ser utilizado e o local adequado de inserção; devendo-se considerar que para o bom resultado do tratamento, é necessária a boa higienização bucal e o acompanhamento profissional.

Positional guidelines for orthodontic mini-implant placement in the anterior alveolar region: a systematic review.

PURPOSE: To investigate the adequacy of potential sites for insertion of orthodontic mini-implants (OMIs) in the anterior alveolar region (delimited by the first premolars) through a systematic review of studies that used computed tomography (CT) or cone beam CT (CBCT) to assess anatomical hard tissue parameters, such as bone thickness, available space, and bone density. MATERIALS AND METHODS: MEDLINE, EMBASE, and the Cochrane Database of Systematic Reviews were searched to identify all relevant papers published between 1980 and September 2011. An extensive search strategy was performed that included the key words "computerized (computed) tomography" and "mini-implants." Information was extracted from the eligible articles for three anatomical areas: maxillary anterior buccal, maxillary anterior palatal, and mandibular anterior buccal. Quantitative data obtained for each anatomical variable under study were evaluated qualitatively with a scoring system. RESULTS: Of the 790 articles identified by the search, 8 were eligible to be included in the study. The most favorable area for OMI insertion in the anterior maxilla (buccally and palatally) and mandible is between the canine and the first premolar. The best alternative area in the maxilla (buccally) and the mandible is between the lateral incisor and the canine, while in the maxillary palatal area it is between the central incisors or between the lateral incisor and the canine. CONCLUSIONS: Although there is considerable heterogeneity among studies, there is a good level of agreement regarding the optimal site for OMI placement in the anterior region among investigations of anatomical hard tissue parameters based on CT or CBCT scans. In this context, the area between the lateral incisor and the first premolar is the most favorable. However, interroot distance seems to be a critical factor that should be evaluated carefully.

Cortical bone thickness of the alveolar process measured with cone-beam computed tomography in patients with different facial types.

INTRODUCTION: The purpose of this study was to determine the cortical bone thickness of the alveolar process in the maxilla and the mandible on cone-beam computed tomographs of adults with low, normal, and increased facial heights. METHODS: This study was conducted on 155 images of adult patients (20-45 years old) who were assigned to the low-angle, normal, and high-angle groups. The thickness of the buccal cortical plates of the maxilla and the mandible, and the palatal cortical plates of the maxilla, were measured. RESULTS: There was no statistically significant difference between the groups regarding mean ages, sex, and sagittal facial types. High-angle patients had significantly lower values than did low-angle patients in all mini-implant insertion sites in both the maxillary and mandibular alveolar bones. The mandibular and maxillary buccal measurements showed a similar pattern; the lowest values were for the high-angle group, followed by the normal group; the highest values were measured in the low-angle patients. CONCLUSIONS: Clinicians should be aware of the probability of thin cortical bone plates and the risk of mini-implant failures at maxillary buccal alveolar mini-implant sites in high-angle patients, and at mandibular buccal alveolar mini-implant sites between the canine and the first premolar in normal and high-angle patients.

Accuracy of orthodontic miniscrew implantation guided by stereolithographic surgical stent based on cone-beam CT-derived 3D images.

OBJECTIVE: To develop surgical stents for cone-beam computed tomography (CBCT) 3-dimensional (3D) image-based stent-guided orthodontic miniscrew implantation and to evaluate its accuracy. MATERIALS AND METHODS: Ten surgical stents were fabricated with stereolithographic appliances (SLAs) according to 3D CBCT image-based virtual implantation plans. Thirty self-drilling miniscrews were implanted at two to three positions on each side of the maxillary or mandibular posterior arches in three phantoms: 20 guided by 10 surgical stents in two phantoms (stent group) and 10 guided freehand in one phantom (freehand group). Six parameters (mesiodistal and vertical deviations at the corona and apex and mesiodistal and vertical angular deviations) were measured to compare variations between the groups. RESULTS: No root damage was found in the stent group, whereas four of 10 miniscrews contacted with roots in the freehand group. In the stent group, deviations in the mesiodistal and vertical directions were 0.15 ± 0.09 and 0.19 ± 0.19 mm at the corona, respectively, and 0.28 ± 0.23 and 0.33 ± 0.25 mm at the apex, respectively; angular deviations in the mesiodistal and vertical directions were 1.47° ± 0.92° and 2.13° ± 1.48°, respectively. In the freehand group, the corresponding results were 0.48 ± 0.46 mm and 0.94 ± 0.87 mm (corona), 0.81 ± 0.61 mm and 0.78 ± 0.49 mm (apex), and 7.49° ± 6.09° and 6.31° ± 3.82°. Significant differences were found in all six parameters between the two groups (Student's t-test, P < .05). CONCLUSIONS: 3D CBCT image-based SLA-fabricated surgical stents can provide a safe and accurate method for miniscrew implantation.

Accuracy of a cone beam computed tomography-guided surgical stent for orthodontic mini-implant placement.

OBJECTIVE: To validate the accuracy of a cone-beam computed tomography (CBCT)-guided surgical stent for orthodontic mini-implant (OMI) placement by quantitatively evaluating the difference between CBCT-prescribed and actual position of mini-implants in preoperative and postoperative CBCT images. MATERIALS AND METHODS: A surgical stent was fabricated using Teflon-Perfluoroalkoxy, which has appropriate biological x-ray attenuation properties. Polyvinylsiloxane impression material was used to secure the custom-made surgical stent onto swine mandibles. CBCT scanning was done with the stent in place to virtually plan mini-implants using a three-dimensional (3D) software program. An appropriate insertion point was determined using 3D reconstruction data, and the vertical and horizontal angulations were determined using four prescribed angles. A custom-designed surveyor was used to drill a guide hole within the surgical stent as prescribed on the CBCT images for insertion of 32 OMIs. The mandibles with a surgical stent in place were rescanned with CBCT to measure the deviations between the virtual planning data and surgical results. RESULTS: The difference between the prescribed and actual vertical angle was 1.01 ± 7.25, and the horizontal difference was 1.16 ± 6.08. The correlation coefficient confirms that there was no intrarater variability in either the horizontal (R  =  .97) or vertical (R  =  .74) vectors. CONCLUSIONS: The surgical stent in this study guides mini-implants to the prescribed position as planned in CBCT. Since the statistical difference was not significant, the surgical stent can be considered to be an accurate guide tool for mini-implant placement in clinical use.

Tomographic mapping of mandibular interradicular spaces for placement of orthodontic mini-implants.

INTRODUCTION: The purposes of this study were to determine the ideal sites for placement of orthodontic mini-implants in mandibular interradicular spaces by using computed tomography (CT) and to suggest length, diameter, and angulation of the mini-implants. METHODS: CT scans were performed on 15 dry human mandibles with 1-mm tomography slices. Measurements were made at 3, 5, 7, 9, and 11 mm heights from the bone crest. Bone thickness was obtained for the buccolingual, lingual cortex, and buccal cortex areas. The mesiodistal interradicular distance and the distance from the bone crest to the mental foramen were also measured. Simulated placement of 1.5 x 9 mm mini-implants was performed in the tomographic images at angulations 10 degrees , 20 degrees , and 30 degrees . Twenty-four 1.5 x 9 mm mini-implants were then placed in the mandibles, and a new set of CT scans was obtained. Mandibles with implants were sectioned, enabling direct observation. RESULTS: Based on 3000 measurements, means and standard deviations were obtained. The thickness of the mandibular alveolar bone in the cortical buccal and lingual areas, and the interradicular distances increased from the cervical toward the apical aspects. In descending order, the widest spaces were found between the first and second molars, the second premolars and the first molars, and the first and second premolars. Between the premolars, caution should be exercised starting at 9 mm from the bone crest because of the mental foramen. Between the incisors, the placement of interradicular mini-implants is not feasible. Between the first premolars and the canines, no appropriate region was found. Between the lateral incisor and the canine, at a height of 11 mm, a device can be placed but only with utmost care. CONCLUSIONS: The most convenient site for implant placement in a mandible was between the first and second molars, with a 10 degrees to 20 degrees inclination, but orthodontic mini-implants should not exceed 1.5 mm in diameter and 6 mm in length.

Computed tomographic analysis of tooth-bearing alveolar bone for orthodontic miniscrew placement.

INTRODUCTION: When monocortical orthodontic miniscrews are placed in interdental alveolar bone, the safe position of the miniscrew tip should be ensured. This study was designed to quantify the periradicular space in the tooth-bearing area to provide practical guidelines for miniscrew placement. METHODS: Computerized tomographs of 30 maxillae and mandibles were taken from nonorthodontic adults with normal occlusion. Both mesiodistal interradicular distance and bone thickness over the narrowest interradicular space (safety depth) were measured at 2, 4, 6, and 8 mm from the cementoenamel junction. RESULTS: Mesiodistal space greater than 3 mm was available at the 8-mm level in the maxillary anterior region, between the premolars, and between the second premolar and the first molar at 4 mm. In the mandible, sufficient mesiodistal space was found between the premolars, between the molars, and between the second premolar and the first molar at the 4-mm level. Safety depth greater than 4 mm was found in the maxillary and mandibular intermolar regions, and between the second premolar and the first molar in both arches. CONCLUSIONS: Subapical placement is advocated in the anterior segment. Premolar areas appear reliable in both arches. Angulated placement in the intermolar area is suggested to use the sufficient safety depth in this area.

Which region of the median palate is a suitable location of temporary orthodontic anchorage devices? A histomorphometric study on human cadavers aged 15-20 years.

INTRODUCTION: Endosseus implants can provide a reliable anchorage during orthodontic treatment. The midpalatal structures around the sutura palatina mediana (SPM) are of special interest due to increasing placement of orthodontic implants in this area. Knowledge about the osseous conditions at this site is necessary to predict the expected degree of implant osseointegration. METHODS: The upper jaws of 10 human cadavers, aged 15-20 years, were decalcified, and cross-sectional specimens were obtained from four anterior-to-posterior palatal regions for histomorphometric analysis. The analyses focused on the amount of bone and the width of the SPM to determine the anatomical requirements for reliable insertion of palatal implants. RESULTS: Bone density [bone-volume (BV)/ tissue-volume (TV)] in all measured areas was 40-60%. The maximum density was measured at the level of the first premolars (54.9+/-5.9%) and the least values (44.2+/-9.6%) were measured at the level of the interconnecting line of the canines. The mean width of the SPM varies from 1.2 to 0.3 mm in different sections of the palate. In the median sagittal plane, the mean values of bone height to nasal cavity reached >5 mm as far as the level distal of the second premolars. Bone height 2 mm paramedian to the SPM decreased consistently from anterior (4.3+/-0.9 mm) to posterior (2.5+/-0.8 mm). CONCLUSIONS: Our results indicate that the amount and quality of bone along the anterior palatal midline in 15-to-20-year olds is sufficient for orthodontic implantation. Even implantation posterior to the recommended first premolar level, at which orthodontic implants are most often placed, may be suitable. There are some limitations, however, due to small number of samples and variations of anatomical structures.

Assessment of infrazygomatic bone depth for mini-screw insertion.

OBJECTIVE: To investigate the bone depth at the infrazygomatic crest with regard to orthodontic mini-screw insertion. MATERIAL AND METHODS: Twenty-nine adult human dry skulls were imaged using CBCT technology, slice data were generated and multiple measurements were undertaken at three sites associated with the infrazygomatic crest and five different measurement levels. The data were analyzed using intraclass correlation and repeated measures ANOVA. RESULTS: The greatest bone depth was available at, on average, 11.48+/-1.92 mm apical from the cemento-enamel junction of the maxillary first molar and decreased rapidly further apically. Maximum bone depth (7.05+/-3.7 mm) was present at the lowest measurement level. However, here, insufficient clearance to the molar roots was present. Both the measurement site and the level at which the measurements were conducted had a significant impact on bone depth. CONCLUSIONS: When inserting orthodontic mini-screws (6 mm or longer) into the infrazygomatic crest while staying clear of the molar roots perforation of the maxillary sinus or the nasal cavity can be expected, but bone depth varies considerably between individuals.

'Bone map' for a safe placement of miniscrews generated by computed tomography.

OBJECTIVES: The aim of this manuscript is to provide a bone map that can be used as a general guide to determine the areas where miniscrews can be safely anchored. MATERIALS AND METHODS: Twenty-one computed tomographies (CTs) of maxilla and mandible were taken by the imaging centre ORTOSCAN and two measures were taken: --first, the interradicular space in the mesiodistal plane of the maxillary and mandible teeth with slices taken at 3, 6, and 9 mm from the alveolar crest, in the palatine and vestibular slices, --second, the interradicular space in the vestibular-lingual direction. RESULTS: We can see that the greatest amount of mesiodistal bone is between the first and second inferior molars on the vestibular side and between the second and first inferior molars on the lingual side, whereas the least amount of bone on the mesiodistal plane is between the inferior incisors on the vestibular side. To determine the length of the miniscrew, we must take into account that the greatest amount of vestibular-lingual bone is between the first and second inferior molar, whereas the least amount is between the central and lateral inferior incisors. CONCLUSIONS: Mesiodistal values in vestibular are those that must be considered when inserting the microscrew so as not to damage the dental tissue. Mesiodistal measurements taken in palatal-lingual do not present problems when inserting microscrews.

A comparative evaluation of current orthodontic miniscrew systems.

Miniscrew placement has achieved widespread acceptance in orthodontic practice. However, selecting a suitable miniscrew system from among the available brands is not easy. The aim of this article is to help the clinician better understand the features of miniscrew systems currently available on the market and provide a useful guideline for their clinical use. The authors find that the ideal miniscrew design should include biocompatibility, bone-density-guided insertion, immediate loading, and compatibility with modern orthodontic accessories for 3-dimensional orthodontic control.

Anclaje en ortodoncia / Orthodontic Anchorage

El anclaje en ortodoncia es un componente fundamental al momento de realizar una terapia con aparatos fijos, más aún el control del anclaje y los dispositivos que se emplean para tal efecto representan un pilar básico cuando se busca conseguir tratamiento ortodóncico de éxito. Este trabajo de revisión tiene como objetivo analizar y distinguir las características y particularidades básicas de los distintos tipos de anclaje empleados para el control de la fuerza empleada durante la terapia ortodóncica. Para ello se conceptualiza, clasifica y describe los principios de anclaje, así como ventajas, indicaciones y aplicaciones de algunos dispositivos de refuerzo de anclaje como la barra transpalatina (en adelante BTP), arco lingual, botón de Nace y los microtornillos, con el propósito de seleccionar adecuadamente la aparatología de acuerdo a un buen diagnóstico

Pegado directo de braquetes ortodóncicos / Direct Paste orthodontic Braquet

La aparente simplicidad del procedimiento de pegado de braquetes puede llevar a cometer errores. La técnica puede indudablemente ser mal realizada, hasta por ortodoncistas con experiencia, quienes no realizan los procedimientos con los cuidados requeridos y la técnica adecuada. El propósito de esta monografía, fue hacer una revisión de la literatura existente con la finalidad de optimizar los resultados y mejorar el tratamiento del paciente, describiendo los mejores resultados obtenidos en experiencias previas, en varios pasos clínicos que envuelve el pegamento de braquetes, sean ellos metálicos o no, en superficies de esmalte, metálica, porcelana y otras, además de comparar el pegamento con dos materiales más utilizados para ese fin: resina compuesta e ionómero de vidrio