Mini-implants and miniplates generate sub-absolute and absolute anchorage

Displacement and stress distribution pattern during complete mandibular arch distalization using buccal shelf bone screws - A three-dimensional finite element study

BACKGROUND

To evaluate and compare the distribution of stress and displacement of teeth during mandibular arch distalization using buccal shelf screws.

MATERIALS AND METHODS

Three three-dimensional finite element models of mandibular arch were constructed with third molars extracted. Models 1, 2, and 3 were constructed on the basis of the lever arm heights of 0 mm, 3 mm, and 6 mm, respectively, between the lateral incisor and canine. A buccal shelf screw was placed at the area in the second molar region with the initial point of insertion being inter-dental between the first and second molars and 2 mm below the mucogingival junction. MBT pre-adjusted brackets (slot size 0.022 × 0.028") were placed over the clinical crown's center with a 0.019 × 0.025" stainless-steel archwire on three models. A retraction force of 300 g was applied with buccal shelf screws and a lever arm bilaterally using nickel-titanium closed coil springs. The displacement of each tooth was calculated on X, Y, and Z axes, and the von Mises stress distribution was visualized using color-coded scales using ANSYS 12.1 software.

RESULT

The maximum von Mises stress in the cortical and cancellous bones was observed in model 1. The maximum von Mises stress in the buccal shelf screw and the cortical bone decreased as the height of the lever arm increased. Applying orthodontic forces at the level of 6 mm lever arm height resulted in greater biomechanical bodily movement in distalization of the mandibular molars compared to when the orthodontic forces were applied at the level of 0 mm lever arm height.

CONCLUSION

Displacement of the entire arch may be dictated by a direct relationship between the center of resistance of the whole arch and the line of action generated between the buccal shelf screw and force application points at the archwire, which makes the total arch movement highly predictable.

Finite element analysis of a newly designed miniplate for orthodontic anchorage in the maxillary anterior region

INTRODUCTION

Multiple force vector applications may be indicated when an arch segment or en masse intrusion is needed. This finite element method study aimed to evaluate the total deform the stress yielded in the bone and the miniplate when forces with different directions and magnitudes were applied.

METHODS

First, the prototyped skull model was fabricated on the basis of computed tomography (CT) scans. On this model, the miniplate was fixed, and orthodontic appliances were attached. Then, a 3-dimensional finite element model was constructed by reproducing the characteristics of the physical model. Seven situations were investigated, which diverged in the point of force application, the direction and the number of force vectors, and the force magnitudes.

RESULTS

When the force was applied at 1 point, similar behavior could be observed concerning the deformation and the stress in the miniplate, the maxilla, and the screw holes. Most deformation and stress appeared in the transmucosal arm below the step bend and at the force application point. The angled vectors (-45° and 30°) presented smaller values concerning the vertical vectors. Similar or better performances could be observed when the forces were simultaneously applied at the 2 points.

CONCLUSIONS

The newly designed miniplate showed similar or improved performances when multiple vectors were applied at the 2 points simultaneously compared with the force applied at 1 point. This newly designed miniplate may present improved performance in a clinical situation when multiple forces are demanded.

What changes in the biology of bone movement induced with mini-implants/miniplates is the synchronicity

Introduction:

Induced tooth-bone movement occurs by a synchronicity of dental and bone phenomena, thanks to the osteocytic network, which is a three-dimensional network that controls the bone shape or design.

Objective:

To describe the tooth-bone movement induced by enhanced anchorage, divided into three distinct moments: zero, start and stop.

Question:

From this description, the main question arises: with the use of mini-implants/miniplates, what changes in the biology of induced tooth-bone movement? The answer is: nothing changes, either biologically or microscopically.

Conclusion:

This technique optimizes the treatment time, and the range of therapeutic possibilities is broadened, thanks to the synchronicity of phenomena - which remain the same, in all teeth and bones, yet in a synchronized manner. Bone anchorage represents synchronicity in induced tooth-bone movement.

Effect of platelet-rich plasma on the rate of orthodontic tooth movement

INTRODUCTION

This study aimed to evaluate the effect of platelet-rich plasma (PRP) on the rate of orthodontic tooth movement (OTM) during en-masse anterior retraction.

METHODS

Twenty adult patients with Angles Class I bimaxillary protrusion or crowding requiring first premolar extraction for routine orthodontic treatment were divided into control and experimental groups. The control group did not receive PRP, whereas the experimental group received PRP in the alveolar mucosa of the maxillary 6 anterior teeth just before starting en-masse retraction. Measurements were recorded on digital models made from scanned plaster casts at the beginning of space closure and the end of 3 months. The overall rate of OTM between both groups was compared. The amount of anchorage loss and type of anterior retraction on lateral cephalogram was also compared between the groups.

RESULTS

The overall rate of OTM was minimally increased but not statistically significant in the experimental vs control group (P = 0.838). Anterior retraction parameters in both groups showed incisors moving primarily by controlled tipping and partly by translation. An intergroup comparison of all cephalometric parameters for anchorage loss and anterior retraction showed statistically insignificant differences between both groups.

CONCLUSIONS

PRP is ineffective in accelerating the rate of OTM during en-masse anterior retraction.

Effect of local administration of bisphosphonate on orthodontic anchorage – A systematic review of animal studies

BACKGROUND:

Pharmacological means of anchorage control can improve patient compliance. Bisphosphonates could be helpful in orthodontic anchorage control if their actions could be localized to limit (or control) unwanted tooth movement while not interfering with the desired tooth movement.

OBJECTIVE:

This systematic review aimed to examine and evaluate the quality of all animal studies that reported the effect of locally administered bisphosphonate on limiting orthodontic tooth movement.

DATA SOURCES:

An electronic search was conducted in the PubMed-Medline, Scopus, Google Scholar, and Cochrane databases till May 2022, using the keywords anchorage, anchorage loss, molar movement, posterior tooth movement, incisor movement, incisor retraction, anterior retraction, unwanted tooth movement, tooth displacement, tooth movement forward, bisphosphonate, local bisphosphonate administration, bisphosphonate injection, and bbisphosphonate vestibular induction. Only studies involving localized bisphosphonate administration for anchorage purposes were taken into account.

DATA SELECTION:

Animal studies that simulated orthodontic tooth movement after localized injection of bisphosphonate and evaluated the rate of tooth movement were included in the review.

DATA EXTRACTION AND ANALYSIS:

The quality of the studies was assessed by using ARRIVE guidelines (Animal Research: Reporting of In Vivo Experiments). Bias in the studies was analyzed by SYRCLE's tool (Systematic Review Centre for Laboratory Animal Experimentation) for risk of bias.

RESULTS:

The search strategy yielded 925 titles. After screening, 908 articles were discarded because they did not fulfill the inclusion/exclusion criteria based on the title and abstract. The remaining 16 articles were read entirely, of which nine were excluded as they involved systemic administration of bisphosphonates. Finally, after careful consideration, seven papers that met our inclusion criteria were included in the qualitative analysis. The majority of studies were assessed to have an uncertain risk of bias, with just one deemed low risk of bias.

CONCLUSION:

This systematic review found that bisphosphonates limit orthodontic tooth movement around the application site without affecting adjacent sites. More potent bisphosphonates in smaller doses or less potent bisphosphonates in higher frequencies have been proposed to improve outcomes. However, the data quality is insufficient to recommend a protocol for bisphosphonate administration for anchoring control. Long-term studies evaluating various types, frequencies, and dosages of bisphosphonates are required to clarify the effects on orthodontic tooth movement.

REGISTRATION NUMBER FOR PROSPERO:

CRD42021224033

Intrusion of posterior teeth using miniplates: intrusive mechanics is not the same as intrusion force

Objective:

Biologically explain some of the bone mechanisms involved in the intrusion, or intrusive effect, of teeth submitted to skeletal open bite correction using four miniplates.

Methods:

The results of dental intrusion were measured and compared in 3D reconstructions of cone beam computed tomography scans taken before and after treatment of 20 patients with skeletal open bite, aged between 18 and 59 years.

Results:

The results allow deducing that the compression and traction forces biologically promoted deformation or deflection of the osteocyte network that controls bone design, and these effects involved the external and internal surfaces of the bone, with the formation of new layers, including the cervical portion of the alveolar bone crest. This helps understanding how dental intrusion occurs in intrusive mechanics, whose forces are of inclination rather than intrusion. The root resorptions caused by the use of miniplates were insignificant, due to the more homogeneous distribution of forces in the several teeth simultaneously involved.

Conclusion:

Imaging studies in CT scans tend to capture in details the subperiosteal and endosteal phenomena of dental intrusion - before and after the application of intrusive mechanics -, in the form of a set of modifications called dental intrusion or intrusive effect .

Orthopaedic and orthodontic treatment with hyrax, Class III elastics on mandibular miniplates, maxillary mini-implants in a Class III adolescent: A case report

BACKGROUND

The treatment of Skeletal Class III malocclusion continues to be considered as one of the biggest challenges in orthodontics as the success of its correction is largely unpredictable. Early diagnosis and treatment are highly recommended to eliminate primary etiological factors and prevent an increase in severity of the existing malocclusion. However, if the diagnosis is delayed until adulthood, treatment becomes restricted to orthognathic surgery due to limited or no remaining growth potential left. The inherent risks involved with the surgical procedures often preclude the patients from opting for it, thus leaving the orthodontist with no option but to perform possible compensatory treatments to improve facial aesthetics and restore functional occlusion.

OBJECTIVE

To report the case of a 15-year old boy (adolescent) with Skeletal Class III malocclusion, a concave facial profile with an anterior crossbite and no incisor visibility during smile.

METHODS

Intra-oral skeletally anchored maxillary protraction (I-SAMP) and mini-implants associated with fixed appliance to aid in the correction of the skeletal bases and subsequently relieve the dental crowding.

RESULTS

After 36 months of treatment, functional normal occlusion with a Class I molar and canine relation was achieved. The consequential increase in upper lip thickness and decrease in lower lip fullness alongwith an increased exposure of maxillary incisors during smile resulted in a significant improvement of the patient's facial profile and an aesthetically pleasing smile.

Comparison of Anchorage Efficiency of Orthodontic Mini-implant and Conventional Anchorage Reinforcement in Patients Requiring Maximum Orthodontic Anchorage: A Systematic Review and Meta-analysis

OBJECTIVE

To compare the clinical effectiveness of mini-implants (MIs) and conventional anchorage appliances used for orthodontic anchorage reinforcement in patients with class I or II malocclusion with bimaxillary protrusion.

MATERIALS AND METHODS

Literature search was conducted through PubMed, Embase, and Cochrane from inception to July 2018. The following Medical Subject Heading terms were used for the search string: "skeletal anchorage", "temporary anchorage devices", "miniscrew implant", "mini-implant", "micro-implant". Standardized mean difference (SMD) and 95% confidence interval (CI) of horizontal and vertical movements of teeth from baseline were used for comparison.

RESULTS

A total of 12 studies were included in the final analysis. MI group significantly lowered mesial movement of molars compared to conventional anchorage group (SMD = -1.48, 95% CI = -2.25 to -0.72; P = .0002). There was significantly higher retraction of incisors in the MI group than in the conventional group (SMD = -0.47 mm, 95% CI = -0.87 to -0.07; P = .02). No significant difference was seen in vertical movement of molars (SMD = -0.21 mm, 95% CI = -0.87 to 0.45; P = .52) and incisors (SMD = -0.30, 95% CI = -1.18 to 0.58; P = .5).

CONCLUSION

MIs seem to be more effective than the conventional anchorage devices in terms of minimizing unintended mesial movement of molars with maximum retraction of anterior teeth.

Biomechanical analysis of distalization of mandibular molars by placing a mini-plate: A finite element study

Objective

The objective of this study was to analyze the patterns of tooth movements when distalization of mandibular molars using a mini-plate took place. A finite element analysis was applied to analyze patterns of tooth movements.

Methods

The model of the mandible and teeth were used to build a finite element analysis model, and a mini-plate was inserted in the mandibular ramus. Two different orthodontic forces were established for displacement of mandibular molars. Orthodontic forces were applied at the level of the bracket and at the level of the cemento-enamel junction in the mandibular canine respectively.

Results

orthodontic forces at the level of the cemento-enamel junction resulted in a greater biomechanical bodily movement in distalization of the mandibular molars compared to when the orthodontic forces were applied at the level of the bracket. Applying orthodontic forces to the cemento-enamel junction also resulted in unwanted greater extrusive movements in distalization of the mandibular molars compared to the bracket level.

Conclusions

With considering the mode of orthodontic teeth movement, applying different vertical orthodontic forces for distalization of mandibular molars can lead to more effective distalization of teeth.

Orthodontic camouflage of skeletal Class III malocclusion with miniplate: a case report

Introduction:

Skeletal Class III malocclusion is often referred for orthodontic treatment combined with orthognathic surgery. However, with the aid of miniplates, some moderate discrepancies become feasible to be treated without surgery.

Objective:

To report the case of a 24-year-old man with severe skeletal Angle Class III malocclusion with anterior crossbite and a consequent concave facial profile.

Methods:

The patient refused to undergo orthognathic surgery; therefore, orthodontic camouflage treatment with the aid of miniplates placed on the mandibular arch was proposed.

Results:

After 18 months of treatment, a Class I molar and canine relationship was achieved, while anterior crossbite was corrected by retraction of mandibular teeth. The consequent decrease in lower lip fullness and increased exposure of maxillary incisors at smiling resulted in a remarkable improvement of patient's facial profile, in addition to an esthetically pleasing smile, respectively. One year later, follow-up revealed good stability of results.