Revisiting the Complications of Orthodontic Miniscrew

Miniscrew has been used widely as an effective orthodontic anchorage with reliable stationary quality, ease of insertion and removal techniques, immediate or early loading, flexibility in site insertion, less trauma, minimal patient cooperation, and lower price. Nonetheless, it is not free of complications, and they could impact not only the miniscrew success rate but also patients’ oral health. In this article, literature was searched and reviewed electronically as well as manually to evaluate the complications of orthodontic miniscrew. The selected articles are analyzed and subcategorized into complications during and after insertion, under loading, and during and after removal along with treatment if needed according to the time. In addition, the noteworthy associated factors such as the insertion and removal procedures, characteristics of both regional and local anatomic structures, and features of the miniscrew itself that play a significant role in the performance of miniscrews are also discussed based on literature evidence. Clinicians should notice these complications and their related factors to make a proper treatment plan with better outcomes.

Interradicular distance and alveolar bone thickness for miniscrew insertion: a CBCT study of Persian adults with different sagittal skeletal patterns

Background

This study aimed to assess the interradicular distance and alveolar bone thickness of Persian adults with different sagittal skeletal patterns for miniscrew insertion using cone-beam computed tomography (CBCT).

Methods

This cross-sectional study was conducted on maxillary and mandibular CBCT scans of 60 patients (18–35 years) in three groups (n = 20) of class I, II and III sagittal skeletal pattern. Anatomical and skeletal parameters were measured at 2, 4 and 6 mm apical to the cementoenamel junction (CEJ) by one examiner. The intra- and inter-class correlation coefficients were calculated to assess the intra, and interobserver reliability. Data were analyzed by ANOVA and Tukey’s test (alpha = 0.05).

Results

The intra- and interobserver reliability were > 0.9 for all parameters. The largest inter-radicular distance in the maxilla was between the central incisors (1–1) in classes I and III, and between premolars (4–5) in class II patients. The largest inter-radicular distance in the mandible was between molar teeth (6–7) in all three classes. The buccal cortical plate thickness was maximum at the site of mandibular first and second molars (6–7). The posterior maxilla and mandible showed the maximum thickness of cancellous bone and alveolar process. Wide variations were noted in this respect between class I, II and III patients.

Conclusions

The area with maximum inter-radicular distance and optimal alveolar bone thickness for miniscrew insertion varies in different individuals, depending on their sagittal skeletal pattern.

Interradicular sites and cortical bone thickness for miniscrew insertion: A systematic review with meta-analysis

INTRODUCTION

Safe zone maps are useful for the clinician to plan miniscrew insertion and possibly reduce radiation exposure. This study aimed to investigate the available evidence regarding the presence of sufficient interradicular space and adequate cortical bone thickness in patients with a complete permanent dentition, in the vestibular and palatal or lingual interradicular sites, mesial to the second molar.

METHODS

PubMed, Scopus, Web of Science, Cochrane Library, and OpenGrey databases were searched up to January 2019 for observational studies involving patients with fully erupted second molars that investigated the amount of interradicular space and/or the cortical thickness of the alveolar processes using 3-dimensional data sets. A custom tool was prepared and used to assess the risk of bias in individual studies. A meta-analysis was performed when at least 4 different studies evaluated 1 identical parameter homogeneously. Publication bias was assessed with the Egger linear regression test.

RESULTS

Twenty-seven observational articles were included in the qualitative synthesis. Only 11 articles were at low risk of bias. Fifteen articles were included in the meta-analysis. The results were graphically reported in "safe-zone" maps.

CONCLUSIONS

In the maxilla, the most suitable insertion sites are those from mesial to the first molar to distal to the first premolar, and between the canine and the lateral incisor, all at 6 mm from the cementoenamel junction. In those areas, the cortical bone has adequate thickness, not requiring predrilling. In the mandible, the preferable vestibular interradicular spaces are those between first and second molars and between first and second premolars, both at 5 mm from the cementoenamel junction, and predrilling is suggested in these areas.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42016042081.

Three-dimensional Evaluation of Interradicular Areas and Cortical Bone Thickness for Orthodontic Miniscrew Implant Placement Using Cone-beam Computed Tomography

Background

Factors that influence anchorage of the orthodontic miniscrew implants are interradicular areas and cortical bone thickness.

Aims and Objectives

The aim of this study was to evaluate the three-dimensional interradicular areas and the buccal cortical bone thickness in Indian patients using cone beam computed tomography (CBCT) images, and to find the suitable and safe sites for orthodontic miniscrew implant placement.

Materials and Methods

CBCT images of 20 patients were divided into three planes as axial, coronal, and sagittal. Measurements, that is, mesiodistal distance and buccal cortical bone thickness were taken at five different heights from the cementoenamel junction (CEJ) toward apical region.

Results

In the maxilla, the safe sites for placing miniscrew implant were between the second premolar and first molar at 10-mm height, whereas in the mandible, the safe sites for placing miniscrew implant were between the first and second premolar at 6-, 8-, and 10-mm height, between the second premolar and first molar at 10-mm height, and between the first and second molar at 8- and 10-mm height.

Conclusion

CBCT can be effectively used to evaluate interradicular areas and cortical bone thickness in predicting the safe and suitable sites for placing orthodontic miniscrew implants.

Optimal sites for mini-implant insertion in the lingual or palatal alveolar cortical bone as assessed by cone beam computed tomography in South Indian population

OBJECTIVES

To determine the optimal sites of mini-implant placement in the palatal alveolar cortical bone by using cone beam computed tomography (CBCT).

SUBJECTS AND METHODS

Cone beam computed tomography records of 60 patients were divided into two groups of equal sizes, based on age and sex. The images were analysed using Planmeca Romexis Software (Version 4.1.2). The measurements were made in axial sections of the maxilla and mandible, at 2, 4 and 6 mm from the CEJ. The optimal sites were defined in terms of (a) Palatal or lingual alveolar cortical bone thickness and (b) Mesiodistal palatal or lingual inter-radicular width.

RESULTS

The optimal site for mini-implant insertion, anteriorly, was the canine-lateral incisor embrasure in both the jaws. Posteriorly, the inter-molar embrasure in the mandible and the molar-premolar embrasure in the maxilla were optimal sites. Females demonstrated significantly lesser bone widths in all areas of the maxilla (P < .05) but greater bone thickness in the mandibular regions, as compared to males. The adolescent age group demonstrated a significantly lesser bone thickness but greater mesiodistal widths than the adult population in both the jaws (P < .05).

CONCLUSION

The optimal sites for mini-implant insertion were the anterior canine-lateral incisor and posterior buccal inter-radicular embrasures, in both the jaws. Significant differences existed between age and gender groups, which need to be kept in mind while choosing the locations for placing mini-implants.

Effect of orthodontic treatment on alveolar bone thickness in adults: a systematic review

Objectives:

This review aimed at evaluating changes in alveolar bone thickness after completion of orthodontic treatment.

Methods:

Only prospective clinical studies that reported bone thickness in adult patients undergoing non-surgical orthodontic treatment were considered eligible. MEDLINE, EMBASE and LILACS databases were searched for articles published up to July 2018.

Results:

A total of 12 studies met the selected criteria. Most of the studies showed that orthodontic treatment produces a reduction in bone thickness of incisors, mainly at the palatal side.

Conclusion:

On patients undergoing different orthodontic treatment techniques, there was a significant bone thickness reduction, mainly on the palatal side.

Clinical relevance:

These findings are relevant and have to be considered in diagnosis and planning of tooth movement, in order to prevent the occurrence of dehiscence and fenestration in alveolar bone.

Evaluation of Interdental Spaces of the Mandibular Posterior Area for Orthodontic Mini-Implants with Cone-Beam Computed Tomography

INTRODUCTION

The use of mini-implants has increased in recent years because of their role in absolute anchorage, but the placement sites may affect the success or failure of the procedure, so it is very important to determine the appropriate and safe location for orthodontic mini-implants. On the other hand, the Cone Beam Computed Tomography (CBCT), which offers clear 3-Dimentional (3D) images, has been widely used in orthodontics and implant dentistry for surgical guidance of mini-implant placement.

AIM

The aim of this retrospective study was to evaluate inter-radicular spaces between mandibular canines to second molars using cone beam 3D images.

MATERIALS AND METHODS

In this retrospective cross-sectional descriptive study, maxillofacial CBCT scan data were obtained from 40 adults. The 3D images were evaluated in five axial sections at 2, 4, 6, 8 and 10 mm from the cementoenamel Junction (CEJ). To determine inter-radicular spaces, tangent lines were drawn buccolingually to the roots in axial section and the minimum distance between these two lines was measured. The data was analysed using Friedman test with SPSS(ver.13).

RESULTS

Interradicular spaces of canine to second molar increased from cervical to apical direction. The maximum distance was recorded at 4 mm from the CEJ between first and second molars.

CONCLUSION

According to our findings there is a distinct pattern of inter-radicular space changes in mandible. Attention to this pattern during placement of mini-implants can ensure the safety of the procedure.

Comparison of interradicular distances and cortical bone thickness in Thai patients with Class I and Class II skeletal patterns using cone-beam computed tomography

Purpose

This study evaluated and compared interradicular distances and cortical bone thickness in Thai patients with Class I and Class II skeletal patterns, using cone-beam computed tomography (CBCT).

Materials and Methods

Pretreatment CBCT images of 24 Thai orthodontic patients with Class I and Class II skeletal patterns were included in the study. Three measurements were chosen for investigation: the mesiodistal distance between the roots, the width of the buccolingual alveolar process, and buccal cortical bone thickness. All distances were recorded at five different levels from the cementoenamel junction (CEJ). Descriptive statistical analysis and t-tests were performed, with the significance level for all tests set at p<0.05.

Results

Patients with a Class II skeletal pattern showed significantly greater maxillary mesiodistal distances (between the first and second premolars) and widths of the buccolingual alveolar process (between the first and second molars) than Class I skeletal pattern patients at 10 mm above the CEJ. The maxillary buccal cortical bone thicknesses between the second premolar and first molar at 8 mm above the CEJ in Class II patients were likewise significantly greater than in Class I patients. Patients with a Class I skeletal pattern showed significantly wider mandibular buccolingual alveolar processes than did Class II patients (between the first and second molars) at 4, 6, and 8 mm below the CEJ.

Conclusion

In both the maxilla and mandible, the mesiodistal distances, the width of the buccolingual alveolar process, and buccal cortical bone thickness tended to increase from the CEJ to the apex in both Class I and Class II skeletal patterns.

Hard and soft tissue considerations at mini-implant insertion sites

Various factors influence where orthodontic mini-implants will be placed. This article highlights the pertinent variables that should find consideration when planning the placement of orthodontic mini-implants.

Biomechanical characteristics and reinsertion guidelines for retrieved orthodontic miniscrews

OBJECTIVES

To analyze morphological variations of retrieved orthodontic miniscrews and to evaluate the mechanical properties that may adversely affect relocation of miniscrews.

MATERIALS AND METHODS

Retrieved miniscrews were classified with scanning electron microscopy according to the degree of morphological deformation of the tip. To evaluate the differences in mechanical characteristics during reinsertion, changes in insertion torque, insertion time and differences in successful insertion load were compared between unused controls and retrieved miniscrews. In addition, surface composition analysis of retrieved miniscrews was performed using energy-dispersive x-ray spectroscopy.

RESULTS

Significant tip deformation was evident in the majority (>84.5%) of retrieved miniscrews. Initial conditions such as insertion site or duration of insertion were not associated with the presence of tip deformation. Insertion load for successful bone penetration increased in proportion to the degree of tip deformation; however, serial changes in insertion torque were similar to those of the controls. Deposited debris such as carbon, calcium, and phosphorus was noted on the retrieved miniscrews.

CONCLUSION

Miniscrews retrieved after primary insertion exhibited decreased cutting ability due to deformation of the tip structure, as well as surface contamination.

A comparison of tapered and cylindrical miniscrew stability

OBJECTIVES

This study compared the stability of tapered miniscrews with cylindrical miniscrews.

MATERIALS/METHODS

One hundred and five tapered and 122 cylindrical self-drilling miniscrews were placed into the maxillary and mandibular buccal alveolar areas of 132 patients (43 males and 89 females). The insertion torque and removal torque were measured and Periotest values (PTVs) were recorded at implantation.

RESULTS

The success rates of the tapered and cylindrical miniscrews examined were similar. In the maxilla, the insertion torque of the tapered miniscrews (8.3 Ncm) was significantly higher than that of the cylindrical miniscrews (6.3 Ncm) (P < 0.05). The PTVs of the tapered miniscrews were statistically significantly lower in the maxilla (P < 0.05). The removal torque values showed no significant difference between the tapered and cylindrical miniscrews in the upper and lower buccal areas (P > 0.05).

CONCLUSIONS

Tapered miniscrews had higher initial stability when compared to cylindrical miniscrews, whereas the clinical success rates and removal torques were similar between the two designs. The long-term stability is not directly affected by the miniscrew design.

Evaluation of mandibular cortical bone thickness for placement of temporary anchorage devices (TADs)

Objective

In this study, we measured the cortical bone thickness in the mandibular buccal and lingual areas using computed tomography in order to evaluate the suitability of these areas for application of temporary anchorage devices (TADs) and to suggest a clinical guide for TADs.

Methods

The buccal and lingual cortical bone thickness was measured in 15 men and 15 women. Bone thickness was measured 4 mm apical to the interdental cementoenamel junction between the mandibular canine and the 2nd molar using the transaxial slices in computed tomography images.

Results

The cortical bone in the mandibular buccal and lingual areas was thicker in men than in women. In men, the mandibular lingual cortical bone was thicker than the buccal cortical bone, except between the 1st and 2nd molars on both sides. In women, the mandibular lingual cortical bone was thicker in all regions when compared to the buccal cortical bone. The mandibular buccal cortical bone thickness increased from the canine to the molars. The mandibular lingual cortical bone was thickest between the 1st and 2nd premolars, followed by the areas between the canine and 1st premolar, between the 2nd premolar and 1st molar, and between the 1st molar and 2nd molar.

Conclusions

There is sufficient cortical bone for TAD applications in the mandibular buccal and lingual areas. This provides the basis and guidelines for the clinical use of TADs in the mandibular buccal and lingual areas.

Direct and tomographic dimensional analysis of the inter-radicular distance and thickness of the vestibular cortical bone in the parasymphyseal region of adult human mandibles

We calculated the inter-radicular distances between the canine, and first and second premolars, of human mandibles and the thickness of the cortical bone at adjacent sites using computed tomographic (CT) imaging, and assessed the precision of the dimensional assessment made by CT compared with the same measurement made directly with calipers. We examined 100 adult cadaveric dentate human hemimandibles. At the level at which monocortical screws are inserted to place miniplates according to the current technique used to treat mandibular fractures, points A, B, and C referred to the canine, and first and second premolars, and were marked to calculate the level of the CT slice and as the reference for sectioning of the hemimandible. Our findings showed that there was no significant difference in the inter-radicular distance or in the thickness of cortical bone between the sides of the mandible. The vestibular cortical bone was less than 3.0mm thick in 91 of the samples. In 98 of the samples the inter-radicular distance between the canine and the first and second premolars was more than 2mm. There was no significant difference in micrometric precision between the dimensional assessment on CT and direct measurement using a caliper. In the region of the mental foramen the screws have cortical bone less than 3mm thick in which to be anchored. The inter-radicular distance suggests that there is a minimal risk of radicular injury when miniscrews are inserted between the alveolar structures. CT is a reliable tool for measuring the inter-radicular distance and the thickness of mandibular cortical bone.

"Safe zones" for miniscrew implant placement in different dentoskeletal patterns

OBJECTIVE

To assess the influence of different dentoskeletal patterns on the availability of interradicular spaces and to determine the safe zones for miniscrew implant placement.

MATERIALS AND METHODS

Periapical radiographs of 60 subjects with skeletal Class I, II, or III patterns were examined. For each interradicular site, the areas and distances at 3, 5, 7, 9, and 11 mm from the alveolar crest were measured.

RESULTS

In the maxilla, the greatest interradicular space was between the second premolar and the first molar. In the mandible, the greatest interradicular space was between the first and second molars, followed by the first and second premolars. Significant differences in interradicular spaces among the skeletal patterns were observed. Maxillary interradicular spaces, particularly between the first and second molars, in the subjects with skeletal Class II patterns, were greater than those in the subjects with skeletal Class III patterns. In contrast, in the mandible, interradicular spaces in the subjects with skeletal Class III patterns were greater than those in the subjects with skeletal Class II patterns.

CONCLUSIONS

For all skeletal patterns, the safest zones were the spaces between the second premolar and the first molar in the maxilla, and between the first and second premolars and between the first and second molars in the mandible.

Effects of mandibular incisor intrusion obtained using a conventional utility arch vs bone anchorage

OBJECTIVE

To compare the dentofacial effects of mandibular incisor intrusion using mini-implants with those of a conventional incisor intrusion mechanic, the utility arch.

MATERIALS AND METHODS

Twenty-six deep-bite patients were enrolled to one of the two groups. In group 1 the mandibular incisors were intruded using a 0.16 × 0.22-inch stainless-steel segmental wire connected to two mini-implants. In group 2 the mandibular incisor intrusion was performed using a conventional utility arch. Conventional lateral cephalometric radiographs were taken at pretreatment and at the end of intrusion. Thirty landmarks were identified to measure 23 linear and 20 angular measurements. Intragroup comparisons were made using a paired t-test or a Wilcoxon test. Intergroup comparisons were made using a Student's t-test or a Mann-Whitney U-test.

RESULTS

The duration of intrusion was 5 months for group 1 and 4 months for group 2. In the implant group, the mean amount of change was 0.4 mm/mo for the incisor tip and 0.3 mm/mo for the center of resistance, and in the utility arch group, the mean amount of change was 0.25 mm/mo for the incisor tip and 0.2 mm/mo for the center of resistance. The mandibular incisors showed an average protrusion of 7° in the implant group and 8° in the utility arch group.

CONCLUSIONS

Incisor intrusion that was achieved using an implant-supported segmented archwire was no different than the movement achieved with a conventional intrusion utility arch. The only difference between the two methods was in the molar movement.

Influência da largura do septo inter-radicular sobre a estabilidade dos mini-implantes

OBJETIVO: este estudo teve como objetivo avaliar a influência da largura do septo inter-radicular no local de inserção de mini-implantes autoperfurantes sobre o grau de estabilidade desses dispositivos de ancoragem. MÉTODOS: a amostra consistiu de 40 mini-implantes inseridos entre as raízes do primeiro molar e segundo pré-molar superiores de 21 pacientes, com o intuito de fornecer ancoragem para retração anterior. A largura do septo no local de inserção (LSI) foi mensurada nas radiografias pós-cirúrgicas e, sob esse aspecto, os mini-implantes foram divididos em dois grupos: grupo 1 (áreas críticas, LSI<3mm) e grupo 2 (áreas não críticas, LSI>3mm). A estabilidade dos mini-implantes foi avaliada mensalmente pela quantificação do grau de mobilidade e a partir dessa variável foi calculada a proporção de sucesso. Avaliou-se também: a quantidade de placa, altura de inserção, grau de sensibilidade e período de observação. RESULTADOS: os resultados obtidos demonstraram que não houve diferença estatisticamente significativa para o grau de mobilidade e proporção de sucesso entre os mini-implantes inseridos em septos de largura mesiodistal crítica e não crítica. A proporção de sucesso total encontrada foi de 90% e nenhuma variável demonstrou estar relacionada ao insucesso dos mini-implantes. No entanto, observou-se maior sensibilidade nos pacientes cujos mini-implantes apresentavam mobilidade, e que a falha desses dispositivos de ancoragem ocorria logo após sua inserção. CONCLUSÃO: a largura do septo inter-radicular no local de inserção não interferiu na estabilidade dos mini-implantes autoperfurantes avaliados neste estudo.

[Mapping mini-implant anatomic sites in the area of the maxillary first molar with the aid of the NewTom 3G® system]

INTRODUCTION

The goal of our study was to construct a map of the implant sites in the region of the attached gingiva around the maxillary first molars that would be appropriate locations for placement of miniscrews to serve as orthodontic anchorage.

METHOD

We conducted 58 radiographic examinations with the NewTom 3G(®) cone beam technique. For each interdental space, between upper second bicuspids and first molars (5/6) and between upper first and second molars (6/7), we studied the mesio-distal width and depth of bucco-lingual bone at two different levels, L1 and L2, that corresponded to the lower and upper limits of the attached gingiva in the general population.

RESULTS

The widths of the interdental spaces varied very little between L1 and L2 and their variances were comparable. At the level of the 5/6 space, the interdental widths displayed a Gaussian distribution, which made it possible for us to determine the confidence intervals at the two borders of attached gingiva as a function of age: IC(99%) of L1 = [2.045 ; 3.462] from 12 to 17 years or [1.594 ; 2.519] from 18 to 24 or [1.613 ; 2.5] from 25 to 48 years and IC(99%) of L2 = [2.37 ; 3.69] from 12 to 17 years or [1.5 ; 2.613] from 18 to 24 or [1.546 ; 2.619] from 25 to 48 ans. The interdental depths increased in an apical direction and their variance diminished. Even if the adequacy of the Gaussian law is less reliable in the sagittal plane, we find a greater consistency in depths in the spaces around 5/6 that allows us to establish very precise confidence levels: IC(99%) of L1 = [9.213; 10.575] and IC(99%) of L2 = [10.295; 11.593].

CONCLUSION

The mesial areas of the first molars constitute safe zones for implantation of miniscrews with a maximum of 2-2.3 mm for 12 to 17 years old or 1.5-1.6 mm for 18 to 48 year olds and of a maximum of 9-10 mm in length whether the attached gingival level is strong or feeble. The distal areas of the first molars, because of their great variability, require an individualized radiographic study before any mini/screw can be placed.

Optimal sites for orthodontic mini-implant placement assessed by cone beam computed tomography

OBJECTIVES

To determine (1) the optimal sites for mini-implant placement in the maxilla and the mandible based on dimensional mapping of the interradicular spaces and cortical bone thickness and (2) The effect of age and sex on the studied anatomic measurements.

MATERIAL AND METHODS

The cone beam computed tomography images of 100 patients (46 males, 54 females) divided into two age groups (13-18 years), and (19-27 years) were used. The following interradicular measurements were performed: (1) Buccolingual bone thickness; (2) Mesiodistal spaces both buccally and palatally/lingually; and (3) Buccal and palatal/lingual cortical thicknesses.

RESULTS

In the maxilla, the highest buccolingual thickness existed between first and second molars; the highest mesiodistal buccal/palatal distances were between the second premolar and the first molar. The highest buccal cortical thickness was between the first and second premolars. The highest palatal cortical thickness was between central and lateral incisors. In the mandible, the highest buccolingual and buccal cortical thicknesses were between the first and second molars. The highest mesiodistal buccal distance was between the second premolar and the first molar. The highest mesiodistal lingual distance was between the first and second premolars. The highest lingual cortical thickness was between the canine and the first premolar. The males and the older age group had significantly higher buccolingual, buccal, and palatal cortical thicknesses at specific sites and levels in the maxilla and the mandible.

CONCLUSIONS

A clinical guideline for optimal sites for mini-implant placement is suggested. Sex and age affected the anatomic measurements in certain areas in the maxilla and the mandible.

Tomographic analysis of the interalveolar space and thickness of the vestibular cortical bone in the parasymphyseal region of adult human mandibles

PURPOSE

The aim of this study was to determine by computed tomography (CT) the interalveolar distance on mandible relative to the canine, first and second pre-molar, and the thickness of the cortical bone in the same region.

METHODS

A hundred adult cadaveric dentate human hemi-mandibles were examined. A point (P) above the upper margin of the mental foramen was determined, the height at which monocortical screws are inserted to place miniplate according to the technique to treat mandibular fracture. Then, points A, B and C at the same height as point P, referring to the dental units namely canine, first and second pre-molars were marked to determine the CT cut level to measure cortical bone thickness and the interalveolar distance.

RESULTS

The figures showed no statistically significant difference between the sides. The thickness of the vestibular cortical bone was less than 3.0 mm in 96% of the samples. In 91% of the samples the interalveolar distance between canine, first and second pre-molars was greater than 2 mm, a potentially safe condition to insert 2.0-mm diameter monocortical screws at the study points.

CONCLUSIONS

The individual actual anatomy of the region where screws are to be inserted above the mental foramen is important to perform the technique safely. We believe that the minimal cortical thickness to obtain sufficient screw anchorage should be studied in order to determine the actually safe shortest screw length. It is important to minimize the risk of tooth root damage or nerve injury and the amount of titanium in the human tissues.