Relationship between vertical skeletal pattern and success rate of orthodontic mini-implants

doi:10.1016/j.ajodo.2008.08.032

American Journal of Orthodontics and Dentofacial Orthopedics

Volume 138, Issue 1, July 2010, Pages 51-57

https://doi.org/10.1016/j.ajodo.2008.08.032 Get rights and content

Introduction

The objective of this research was to determine which clinical and skeletal factors are related to the success rate of orthodontic mini-implants in the maxillary and mandibular posterior buccal areas.

Methods

A total of 778 orthodontic mini-implants (Dual-Top Anchor System, Jeil Medical, Seoul, Korea; 1.6 mm diameter, 8 mm length, cylinder shape, self-drilling type) in 306 patients were retrospectively examined. The success rate was calculated according to clinical variables (sex, age, soft-tissue management, placement position, sagittal skeletal classification, arch-length discrepancy, and side) and skeletal variables (articular angle, mandibular plane to palatal plane angle, Frankfort-mandibular plane angle, mandibular plane angle, gonial angle, upper gonial angle, and lower gonial angle). Analysis of variance (ANOVA), chi-square tests, and multiple logistic regression analysis were used for statistical analysis.

Results

The overall success rate was 79.0%. Almost 80% of the failures occurred within the first 4 months. The clinical variables sex, age, soft-tissue management, sagittal skeletal classification, arch-length discrepancy, and side did not show significant differences in the success rate. Although the success rates were significantly different according to placement position (P <0.01), there was no significant difference in the odds ratios among placement positions. In the skeletal variables, average upper gonial angle (84.2%) had a significantly higher success rate than low (75.7%) and high (71.2%) upper gonial angles (P <0.01). High Frankfort-mandibular plane angle (P <0.05) and low upper gonial angle groups (P <0.05) showed significant lower odds ratios than did the other types.

Conclusions

Vertical skeletal pattern might be an important factor for the success of orthodontic mini-implants placed in posterior buccal areas.

Section snippets

Material and methods

The samples in this retrospective study consisted of 778 OMIs (Dual-Top Anchor System, Jeil Medical, Seoul, Korea; 1.6 mm diameter, 8 mm length, self-drilling type; Fig 1) in 306 patients (110 male, 196 female) treated in the Department of Orthodontics at Gachon Dental Hospital, Inchon, Korea. The OMIs were placed in the maxillary and mandibular posterior buccal areas (427 OMIs in 155 extraction patients and 351 OMIs in 151 nonextraction patients) for anchorage reinforcement between January

Results

The overall success rate was 79.0% with a mean period of 12.21 ± 7.88 months (Table I). The mean period of the failed OMIs was 1.84 ± 2.09 months (Table I). Dislodgement of OMIs occurred most frequently in the first month (32.5%), and 80% of failures occurred within the first 4 months (Table II).

In the clinical variables, age had a marginal significance on the success rate (P = 0.055, Table III). Teenagers (76.1%) had a relatively lower success rate than did the twenties (81.7%) and adults

Discussion

To estimate the success rate of OMIs objectively, we confined the sample to the same type of OMIs from 1 manufacturer. Our overall success rate was 79.0%, and almost 80% of failures occurred within the first 4 months (Table I, Table II). Therefore, if an OMI withstands more than 4 months of force application, it will have a greater chance of success. The average time to failure was 1.84 months (Table I, Table II); this was shorter than the 3.40 months in the study of Park et al.¹⁰

In this study,

Conclusions

1.
In clinical variables, sex, age, soft-tissue management, sagittal skeletal classification, arch-length discrepancy, and side were not related to the success rate of OMIs, but placement position might be.
2.
In the skeletal variables, vertical pattern indicators such as Frankfort-mandibular plane angles and upper gonial angles might be important factors for the success rate of OMIs placed in posterior buccal areas.

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Failure rates and factors associated with infrazygomatic crestal orthodontic implants - A prospective study
2023, Journal of Oral Biology and Craniofacial Research
Infrazygomatic crestal (IZC) implants have gained increased popularity over the past few years. Hardly any studies have been done to assess the rate and reasons for failure of IZCs. This prospective study was planned and designed with the primary objective of assessing the rate of failure of bone-screws (BS) placed in the infrazygomatic crest. In continuation, the secondary objective was to assess the factors that were associated with the failure.
The study was carried out by taking a detailed case history, (age, gender, vertical skeletal pattern, medical history), photographic records, radiographs, and clinical examination of a total of 32 randomly selected. patients of south indian origin who required infrazygomatic implants bilaterally as the choice of anchorage conservation to retract their incisors. All selected subjects were required to take a PA Cephalogram after the implant placement. The age of the patients ranged from 18 to 33 with an average age of 25 years. The patient log was maintained which included the treatment mechanics, status of oral hygiene, stability of implants, time of loading of the implant, presence of inflammation and time of failure of implant. The angulation of implant was measured on a digital PA cephalogram using Nemoceph software. These parameters were examined to evaluate independent and dependent variables using the Chi-Square test and Fischer's exact test.
A failure rate 28.1% for IZC placed in the infrazygomatic crest region was observed. Patients with a high mandibular plane angle, poor oral hygiene, immediately loaded implant, peri-implantitis, and severe clinical mobility showed higher failure rates. Variables such as age, gender, sagittal skeletal pattern, length of the implant, type of movement, occluso-gingival position, method of force application, and angle of placement were not significantly associated with implant failure.
Oral hygiene and peri-screw inflammation must be controlled to minimize the failure of bone screws placed in the infrazygomatic crest region. Loading of the implant should be done after a latent period of two weeks. A higher failure rate was observed in patients with vertical growth pattern.
Reliability and accuracy of assessing temporary anchorage device-tooth root contact with cone-beam computed tomography
2021, American Journal of Orthodontics and Dentofacial Orthopedics
This study was aimed at investigating the reliability and accuracy of cone-beam computed tomography (CBCT) diagnosis of contact between a temporary anchorage device (TAD) and tooth root and assessing any effect produced by metal brackets, imaging software program, and image segmentation or color enhancement tools.
Eighteen fresh pig mandibles were used. TADs (Vector, 1.4 × 8 mm) were placed at the buccal intermolar alveolar bone on both sides of the mandibles. With soft tissue kept intact, each mandible underwent CBCT scans (voxel size, 400 μm) before and after placing TADs, and after placing metal brackets on involved molars. Alveolar bone specimens containing the TADs were then exposed to microcomputed tomography (microCT) scans (voxel size, 27 μm) after TAD removal. Two independent raters, blinded of image identity, diagnosed TAD-root contact using ImageJ (National Institutes of Health and the Laboratory for Optical and Computational Instrumentation, University of Wisconsin, Madison, Wis) for microCT; Dolphin (Dolphin Imaging and Management Solutions, Chatsworth, Calif) and Anatomage software programs (Anatomage, Santa Clara, Calif) for CBCT images. Intrarater and interrater reliability and diagnostic accuracy were statistically assessed using Cohen kappa and McNemar tests.
Intrarater and interrater reliability of TAD-root contact diagnoses were perfect for microCT diagnoses (κ = 1), generally moderate to good (κ >0.5) for CBCT diagnoses except for the use of color enhancement tools (κ <0.25). For diagnostic accuracy, there was generally a low agreement (κ <0.45) between CBCT and microCT (gold standard). The percent accuracy ranged from 68.1% to 79.2% and was not different among raters, bracket presence/absence, or software choices (chi-square tests, P >0.05). Overall, diagnostic sensitivity was above 80%, whereas specificity was below 55%.
Despite good reliability, diagnoses of TAD-root contact using 400 μm voxel size CBCT imaging tend to be inaccurate, with a likelihood of high false-positive diagnoses.
Ten years of miniscrew use in a U.S. orthodontic residency program
2020, American Journal of Orthodontics and Dentofacial Orthopedics
Orthodontic miniscrews have become popular not only because they can provide an absolute form of anchorage, but also because they can reduce the required patient compliance when compared with traditional orthodontic anchorage. The objective of this study was to examine success rates of miniscrews placed by orthodontic residents and to evaluate which factors may affect insertion outcomes.
The sample consisted of 109 consecutive miniscrews placed in 60 patients (27 males and 33 females). Miniscrews were placed at 4 different insertion sites (anterior palate [n = 31], palatal alveolar process [n = 25], maxillary buccal alveolar process [n = 15], and mandibular buccal alveolar process [n = 38]). Analysis of variance tests were used to evaluate the influence of insertion sites and anchorage type (direct vs indirect) on the success rate.
The overall success rate for miniscrews was 72.5%. The success rate was 83.9% in the anterior palate, 76% in the palatal alveolar process, 60% in the maxillary buccal alveolar process, and 65.8% in the mandibular buccal alveolar process. The success rate was significantly higher in indirect anchorage (84.2%) compared with direct anchorage (58.8%).
Palatal miniscrews were more successful than buccal miniscrews. Indirect anchorage mechanics had a higher success rate than direct anchorage mechanics.
Distribution and amount of stresses caused by insertion or removal of orthodontic miniscrews into the maxillary bone: A finite element analysis
2019, International Orthodontics
Initial stability of miniscrews is an important factor in their success as orthodontic anchorages. One of the factors affecting this stability is the stresses exerted to the bone by the screw. Since the distribution and extent of stresses and strains produced during insertion or removal of miniscrews had not been measured before, this study used finite element analysis (FEA) to measure these parameters in tapered versus cylindrical screws with or without pilot sockets.
An FEA model of maxilla, pilot hole, and tapered/cylindrical miniscrews were created from 875 CT scan data. The bone cortex was considered 2 mm thick. The cancellous bone was reconstructed below the cortical bone. Miniscrews were modelled on the basis of commercial titanium tapered and cylindrical miniscrews (1.6 mm wide, 8 mm long). The diameter and length of the guiding hole were considered to be 1.1 and 1.5 mm, respectively. The miniscrews were inserted (and removed) between the maxillary second premolar and first molar. Stress/strain produced in the bones or screws were measured.
During screw insertion, in all setups, the highest stress existed within both the bone and screw, when the screw was in the cortical bone; after insertion into the cancellous bone, the stress suddenly dropped. In cylindrical screws, the highest amount of stress was distributed around the neck which was used for screw driving. In tapered screws, the stress was mostly distributed around the front one-third of the screw. During screw removal, the results of four setups were rather similar with stresses concentrated around screw necks, in the depth of the screw hole, and around the bone surface. The greatest bone stress during insertion was caused by the pilot-less tapered screw (10.18 MPa) and the lowest stress was exerted by a pilot-less cylindrical screw (0.74 MPa).
Most of the stress and strain is tolerated by the cortical bone and not the cancellous one. Using cylindrical miniscrews might be more bone-friendly. However, all cases had stresses below tolerable thresholds, and hence are safe.
La stabilité initiale des mini-vis est un facteur déterminant de leur succès en tant qu’ancrage orthodontique. L’un des facteurs influençant cette stabilité est la contrainte exercée sur l’os par la vis. Étant donné que la répartition ainsi que le degré des contraintes et déformations produites lors de l’insertion ou du retrait des mini-vis n’avaient jamais été mesurés auparavant, cette étude a utilisé l’analyse par éléments finis (FEA) pour mesurer ces paramètres sur des vis coniques ou cylindriques avec ou sans douille pilote.
Un modèle FEA de maxillaire, de guide pilote et de mini-vis coniques/cylindriques a été créé à partir de 875 données issues de coupes scanner à faisceaux coniques. Il a été considéré que l’os cortical mesurait 2 mm d’épaisseur. L’os spongieux a été reconstruit sous l’os cortical. Les mini-vis ont été modélisées en se référant aux mini-vis coniques et cylindriques en titane du commerce (1,6 mm de large, 8 mm de long). Le diamètre et la longueur du trou de guidage ont été considérés comme étant respectivement de 1,1 et 1,5 mm. Les mini-vis ont été insérées (et retirées) entre la deuxième prémolaire maxillaire et la première molaire. Les contraintes et déformations produites dans les os ou les vis ont été mesurées.
Lors de l’insertion de la vis, dans toutes les configurations, la contrainte la plus élevée a été relevée à la fois dans l’os et dans la vis, lorsque la vis était dans l’os cortical; après insertion dans l’os spongieux, la contrainte a soudainement diminué. Dans le cas des vis cylindriques, la contrainte la plus forte était répartie autour du col qui a été sollicité lors du vissage. Dans le cas des vis coniques, la contrainte était principalement répartie autour du premier tiers de la vis. Lors du retrait de la vis, les résultats des quatre configurations ont été assez similaires, les contraintes étant concentrées autour du col de la vis, au fond du trou de vis et à proximité de la surface de l’os. La contrainte osseuse la plus forte lors de l’insertion a été causée par la vis conique sans foret pilote (10,18 MPa) et la contrainte la plus faible a été exercée par une vis cylindrique sans foret pilote (0,74 MPa).
La plupart des contraintes et des déformations sont tolérées par l’os cortical mais ne le sont pas par l’os spongieux. L’utilisation de mini-vis cylindriques semblerait respecter davantage les os. Néanmoins, dans toutes les configurations, les contraintes étaient en-dessous de seuils de tolérance, ces mini-vis peuvent par conséquent être utilisées sans risques.
Analysis of the association of IL4 polymorphisms with orthodontic mini-implant loss
2019, International Journal of Oral and Maxillofacial Surgery
The aim of this study was to investigate the association of clinical characteristics and IL4 tag single nucleotide polymorphisms (SNPs; rs2227284 and rs2243268) with orthodontic mini-implant (MI) failure. The sample included 135 subjects of both sexes, mean age 48.7 ± 10 years (range 20–76 years): 104 in the control group (patients without any MI loss) and 31 in the study group (patients presenting ≥1 MI loss). Genotypes were determined by real-time PCR. Bivariate and multivariate analyses were performed (P < 0.05). No association was found between the selected tag SNPs and MI loss. The C allele of the IL4 rs2243268 polymorphism in the recessive model was more frequent in patients who had fewer MIs installed (≤2 vs. >2; P = 0.043, odds ratio 0.65, 95% confidence interval 0.58–0.74). On multivariate analysis, smoking habit was significantly associated with the group with multiple MIs installed (P = 0.036), however the significance of the association with rs2243268 was not maintained. No association was found between the socio-demographic, smoking, or genetic factors studied and MI loss. This study supports the interaction between host and environmental factors and its influence on susceptibility to orthodontic MI failure.
Failure rates of mini-implants inserted in the retromolar area
2019, International Orthodontics
Citation Excerpt :
In terms of the thickness and density of the cortical bone and facial skeletal pattern, there has been consensus that subjects with brachycephalic faces, with small gonial angles and mandibular plane angles, have thicker cortical bone than average and longfaced groups [23–26]. Moon et al. [27] found similar success rates (77%) to those of our study for mini-implants placed inter-radicular in patients with high mandibular plane angle (MPA). This vertical pattern was prevalent in the majority of our patients where the average MPA was 42.2° ± 5.16°.
Anchorage reinforcement is an important issue in orthodontic treatment. There is a lack of evidence regarding the failure rate of mini-implants inserted in the retromolar (RM) area, therefore the purpose of this present study was to evaluate the failure rates of mini-implants inserted in the RM area and to evaluate the factors affecting their stability.
This retrospective cohort study of 102 patients (52 female, 55 male; mean age: 18.6 years; SD: 5.2 years) that had received 110 RM mini-implants for orthodontic treatment from 1.2.2012 to 1.6.2017 was conducted after IRB approval at the department of orthodontics. Clinical notes and photographic images of the patients were analysed to evaluate the dependent and independent variables. The primary outcome was mini-implant failure. Independent variables of patient related factors, mini-implant related factors, orthodontic related factors, surgical related factors, and maintenance-related factors were evaluated by logistic regression models for association to failure rates.
A 23.2% failure rate of mini-implants inserted in the RM area was observed. The patient's right side and inflammation were significantly associated with RM mini-implant failure. The odds ratios (relative risk) for mini-implant failure in the right side, and in mini-implants with inflammation around them were 0.166 and 0.188, respectively.
Failure rate for RM mini-implants were found to be 23.2%. To minimize RM mini-implant failure, clinicians should attempt to reduce inflammation around the mini-implants, especially for mini-implants placed on the right RM area.
Le renforcement de l’ancrage est une question importante en orthodontie. Il n’existe pas suffisamment de données probantes concernant le taux de défaillance des mini-implants insérés dans la zone rétromolaire (RM) ; c’est pourquoi la présente étude visait à évaluer les taux de défaillance des mini-implants insérés dans la zone RM et à évaluer les facteurs qui affectent leur stabilité.
Cette étude de cohorte rétrospective de 102 patients (52 femmes, 55 hommes ; âge moyen : 18,6 ans ; écart-type : 5,2 ans) ayant reçu 110 mini-implants RM pour le traitement orthodontique du 1.2.2012 au 1.6.2017 a été réalisée après approbation du Comité de protection des personnes du département d’orthodontie. Les notes cliniques et les images photographiques des patients ont été analysées pour évaluer les variables dépendantes et indépendantes. Le critère d’évaluation principal était l’échec du mini-implant. Des modèles de régression logistique ont permis de déterminer les facteurs associés au taux d’échec des mini-implants en prenant en compte les variables indépendantes, facteurs liés aux patients, aux mini-implants, à l’orthodontie, à la chirurgie et à l’hygiène.
Un taux de défaillance de 23,2 % des mini-implants insérés dans la zone RM a été observé. Le côté droit du patient et l’inflammation étaient significativement associés à l’échec du mini-implant RM. Les odds ratio (risque relatif) de défaillance des mini-implants du côté droit et de mini-implants avec inflammation périphérique étaient respectivement de 0,166 et 0,188.
Le taux d’échec des mini-implants RM est de 23,2 %. Pour réduire au minimum ce taux, les cliniciens devraient tenter de réduire l’inflammation autour des mini-implants, en particulier les mini-implants placés sur la zone RM droite.

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Original articleRelationship between vertical skeletal pattern and success rate of orthodontic mini-implants

Introduction

Methods

Results

Conclusions

Section snippets

Material and methods

Results

Discussion

Conclusions

Am J Orthod Dentofacial Orthop

Am J Orthod Dentofacial Orthop

Am J Orthod Dentofacial Orthop

Am J Orthod Dentofacial Orthop

Int J Oral Maxillofac Surg

Mini-implant for orthodontic anchorage

J Clin Orthod

Microscrews as orthodontic anchorage

Int J Adult Orthod Orthognath Surg

Microimplant anchorage for treatment of skeletal Class I bialveolar protrusion

J Clin Orthod

Clinical application of micro-implant anchorage

J Clin Orthod

Clinical use and failure of skeletal anchorage system

Original article
Relationship between vertical skeletal pattern and success rate of orthodontic mini-implants