Effects of monocortical and bicortical mini-implant anchorage on bone-borne palatal expansion using finite element analysis

Tooth-Bone-Borne vs Bone-Borne Rapid Maxillary Expanders on Dentoskeletal Changes

Purpose

This study compared the insertion and thickness of the cortical bone, the parallelism of the midpalatal suture, and the skeletal transverse dimension using a microimplant-assisted rapid palatal expansion (MARPE) with those produced by bone-anchored maxillary expander (BAME) in adults.

Patients and Methods

The sample comprised 18 patients (mean age, 29.9±9.4 years) selected for the MARPE group and 18 (mean age 24.8±6.8 years) selected for the BAME group. Cone-Beam computed tomography scans taken just before and after the expansion.

Results

After treatment, there was a significant palatal depth decrease. In addition, maxillary and mandibular width were increased in both groups. Regarding the cortical bone insertion and cortical bone width, it is shown an increase in both groups but those changes are not significant. However, the anterior suture opening effect occurs more frequently in the BAME than in the MARPE device. There are no differences in the frequency of opening of the midpalatal suture in the cases treated with MARPE and BAME, in both cases the most frequent opening morphology is parallel, independently of midpalatal suture maturation.

Conclusion

There are no differences in the use of MARPE or BAME in the parallelism of the middle palatal suture, the cortical bone insertion, and thickness according to the maturation stages of the midpalatal suture but significantly increases the transverse dimensions of the maxillary skeleton.

Analysis of Stress Distribution and Displacement Based on the Miniscrew Positions of the Palatal Slope Bone-borne Expander: A Finite Element Study

OBJECTIVES

 This study aimed to investigate the stress distribution pattern of the palatal slope bone-borne expander on the maxillary area according to a different anteroposterior position of anchored miniscrews using finite element analysis.

MATERIALS AND METHODS

 Nasomaxillary stereolithography files with three different anteroposterior anchored miniscrew positions of the palatal slope bone-borne expander were determined as model A, B, and C. Each model consists of four supported miniscrews. Model A: two anterior miniscrews were located between the maxillary canine and the first premolar, and two posteriors between the second premolar and the first molar. Model B: two anteriors were between the lateral incisor and the canine, and two posteriors were the same as in model A. Model C: two anteriors were the same as in model A, and two posteriors were distal to the first molar. One turn of expander screws was applied. Maximum principal stress, equivalent elastic strain, equivalent von Mises stress, and transverse displacement were evaluated.

RESULTS

 The maximum principal stress was mostly found at the bone-miniscrew interface. Model A exhibited an intersecting area of stress between the supported miniscrews. The highest value of principal stress was in model B, while model C showed a uniform distribution pattern. The elastic strain pattern was similar to the principal stress in all models. The highest value of equivalent von Mises stress was located on the expander screw. The largest amount of transverse displacement of teeth was in model A, while model C exhibited a more consistent transverse displacement than other models. Vertical displacement of posterior teeth was also noticed.

CONCLUSION

 Based on the result, it revealed that the various anteroposterior miniscrew placements of the palatal slope bone-borne expander had various patterns of stress distribution and resulted in various outcomes. It may be inferred that model A's miniscrew location was advantageous for obtaining expansion quantities, but model C's miniscrew position was advantageous for maintaining consistent biomechanics.

Effect of different palatal expanders with miniscrews in surgically assisted rapid palatal expansion: A non-linear finite element analysis

INTRODUCTION

Surgically assisted rapid palatal expansion (SARPE) has been the treatment of choice in subjects presenting skeletally mature sutures.

OBJECTIVE

The purpose of this study was to analyze stress distribution and displacement of the craniofacial and dentoalveolar structures resulting from three types of palatal expanders with surgical assistance using a non-linear finite element analysis.

MATERIAL AND METHODS

Three different palatal expanders were designed: Model-I (tooth-bone-borne type containing four miniscrews), Model-II (tooth-bone-borne type containing two miniscrews), and Model-III (bone-borne type containing four miniscrews). A Le Fort I osteotomy was performed, and a total of 5.0 mm palatal expansion was simulated. Nonlinear analysis (three theory) method (geometric nonlinear theory, nonlinear contact theory, and nonlinear material methods) was used to evaluate stress and displacement of several craniofacial and dentoalveolar structures.

RESULTS

Regardless of the maxillary expander device type, surgically assisted rapid palatal expansion produces greater anterior maxillary expansion than posterior (ANS ranged from 2.675 mm to 3.444 mm, and PNS ranged from 0.522 mm to 1.721 mm); Model-I showed more parallel midpalatal suture opening pattern - PNS/ANS equal to 54%. In regards to ANS, Model-II (1.159 mm) and Model-III (1.000 mm) presented larger downward displacement than Model-I (0.343 mm). PNS displaced anteriorly more than ANS for all devices; Model-III presented the largest amount of forward displacement for PNS (1.147 mm) and ANS (1.064 mm). All three type of expanders showed similar dental displacement, and minimal craniofacial sutures separation. As expected, different maxillary expander designs produce different primary areas and levels of stresses (the bone-borne expander presented minimal stress at the teeth and the tooth-bone-borne expander with two miniscrews presented the highest).

CONCLUSIONS

Based on this finite element method/finite element analysis, the results showed that different maxillary expander designs produce different primary areas and levels of stresses, minimal displacement of the craniofacial sutures, and different skeletal V-shape expansion.

Effects of different distractor positions on the formation of expansion, stress and displacement patterns in surgically assisted rapid maxillary expansion without pterygomaxillary disjunction: a finite element analysis study

Skeletal orthopedic expansion of maxilla is accepted as a reliable method for the treatment of transverse maxillar deficiency in growing patients. The aim of the study was to evaluate the effects of different palatal distractor positions on the expansion, stress and displacement patterns of the structures of craniofacial complex in surgical assisted rapid maxillary expansion without pterygomaxillary disjunction (PTMD) with the help of finite element analysis(FEA). Four facial skeleton models with different distractor positions (first premolar, second premolar, first molar, second molar regions) were created. In all finite element models median and lateral osteotomies were performed, without PTMD. Stress distribution was evaluated after 5 mm activation of the transpalatal distraction in all models using the nonlinear solution method in FEA. Unilateral displacement(mm) and stress distribution(MPa) were measured in three directions (x, y, and z axes) of craniofacial and maxillofacial structures in the symmetrical finite element models. In all models, the unilateral transverse displacements of the anterior teeth were greater than those of the posterior teeth, and the greatest displacement was at the central incisor level. The greatest displacement values at the central incisor level, at the anterior nasal spine(ANS) and at the posterior nasal spine(PNS) levels was measured in Model-IV, III, II and I, respectively. Mean elemental stress(von Mises stress) in the medial pterygoid plate, screw and lateral pterygoid plate regions from highest to lowest was measured in Model-IV, III, II and I, respectively. The maxilla performed outward rotation and tipping movement in all models during the expansion period. Among the distractor positions, the second molar region was found to be the most advantageous one in terms of expansion pattern. Considering the patient's anatomy and clinical conditions, placing the palatal distractor as posteriorly as possible will result in more effective maxillary expansion.

Stress distribution and displacement with four different types of MARPE on craniofacial complex: A three-dimensional finite element analysis

BACKGROUND

Various designs of mini-implants assisted rapid palatal expander (MARPE) appliances can impact treatment effectiveness through their biomechanical effects. The purpose of the study was to study the stress distribution and displacement with four different designs of the MARPE appliance on the craniofacial complex.

METHODS

A 3D finite element model of the craniofacial complex was created from CBCT DICOM data, comprising four distinct groups. Each group consisted of one 4-hole expansion screw positioned between the second premolar and first molar in all models. Group 1 used four single-cortical mini-implants (1.5×8mm) engaging only the palatal cortex. Group 2 employed four mini-implants (1.5×11mm) engaging both the palatal and nasal cortices. Group 3 had monocortical implants on the palatal slopes, while Group 4 was similar to group 3 with implants in the acrylic wings. Comparisons between groups were made for anchorage (groups 1 and 2), mini-implant position (groups 1 and 3) and surface effect (groups 3 and 4). Von Mises stresses and displacements at various skeletal and dental points were evaluated using ANSYS software.

RESULTS

The highest stresses were observed in the maxillary, pterygoid and zygomatic bones, as well as in the mid- palatal suture in all four groups. Downward and forward rotation of the craniofacial complex was noted. Group 2 showed greater skeletal expansion than group 1. Among groups 1 and 3, group 3 showed a better stress distribution. Group 4 showed less dentoalveolar rotation than group 3.

CONCLUSIONS

The MARPE appliances had an impact on the craniofacial complex with stresses on the mid-palatal suture, maxillary bone, pterygoid bones and anterior teeth. Clockwise rotation of the maxilla, zygomatic bones and dentition was noted, while the pterygoid bones and pterygoid suture were displaced backwards. MARPE with bicortical anchorage produces better skeletal expansion. Placing implants on the palatal slopes with acrylic wings results in better skeletal expansion with less clockwise rotation of the dentition.

Comparison of the skeletodental effects of miniscrew-anchored and tooth-anchored facemask treatment in growing patients with skeletal class III malocclusions

INTRODUCTION

This retrospective study aimed to evaluate the skeletal and dental effects of the miniscrew-anchored facemask in skeletal Class III growing patients and compare them with those of conventional tooth-anchored facemasks.

METHODS

Retrospectively a total of 50 patients with skeletal Class III (mean ANB: -1.12°) were investigated and divided into two groups according to the treatment modality. Twenty-five patients were treated using the conventional tooth-anchored facemask (T group: mean age 9.3 ± 1.1 years, mean ANB: -0.93°) whereas the other 25 were treated using a miniscrew-anchored facemask (M group: mean age 9.7 ± 1.3 years. mean ANB: -1.61°). Two miniscrews were placed on the palate for bone anchorage. In both T and M groups, facemasks applied a force of 20-30° down on the occlusal plane, and the force increased from 200 g to 300-350 g per side throughout the treatments. The patients were instructed to wear facemasks for at least 14 h per day. A total of 16 angular and 11 linear cephalometric measurements were analysed to determine the skeletal and dental changes before and after facemask treatment. A paired t-test was used to verify the effects before and after treatment in each group.

RESULTS

All miniscrews were well maintained during treatment. The values of SNA, SN-ANS, ANB and A to N-Perp, which indicate anterior protraction of the maxilla, were significantly higher in the M group compared with the T group (P < .05). Proclination of the maxillary incisors, extrusion and mesialization of the maxillary molars were significantly greater in the T group (P < .05).

CONCLUSIONS

Miniscrew-anchored facemask treatment increased the amount of maxillary protraction and reduced the dental side effects compared with conventional tooth-anchored facemask treatment in growing patients with skeletal Class III malocclusion.

Effects of novel microimplant-assisted rapid palatal expanders manufactured by 3-dimensional printing technology: A finite element study

INTRODUCTION

The expansion effects of several new microimplant-assisted rapid palatal expanders (MARPEs) manufactured by 3-dimensional printing technology were evaluated by finite element analysis (FEA). The aim was to identify a novel MARPE suitable for treating maxillary transverse deficiency.

METHODS

The finite element model was established using MIMICS software (version 19.0; Materialise, Leuven, Belgium). First, the appropriate microimplant insertion characteristics were identified via FEA, and several MARPEs with the above insertion patterns were manufactured by 3-dimensional printing technology. Then, the stress distribution and displacement prediction of the 4 MARPEs and hyrax expander (model E) were evaluated via FEA: bone-borne (model A), bone-tooth-borne (model B), bone-mucous-borne (model C), bone-tooth-mucous-borne (model D).

RESULTS

Monocortical microimplants perpendicular to the cortical bone on the coronal plane resulted in better expansion effects. Compared with a conventional hyrax expander, the orthopedic expansion of each of the 4 MARPEs was far larger, the parallelism was greater, and the posterior teeth tipping rate was lower. Among them, the expansion effects of models C and D were the best; the von Mises peak values on the surfaces of the microimplants were smaller than those of models A and B.

CONCLUSIONS

This study may demonstrate that the 4 MARPEs obtained more advantageous orthopedic expansion effects than a hyrax expander. Models C and D obtained better biomechanical effects and had better primary stability. Overall, model D is the recommended expander for treating maxillary transverse deficiency because its structure acts like an implant guide and is beneficial for the accurate insertion of the microimplant.

Short-term outcomes in the upper airway with tooth-bone-borne vs bone-borne rapid maxillary expanders

BACKGROUND

This study compared the area and minimal section of the nasal cavity, nasopharynx, oropharynx, and hypopharynx in cases treated with different methods of microimplant-assisted expansion.

METHODS

Based on a pilot study to calculate the sample size, 30 patients with transverse maxillary deficiency over 14 years of age were retrospectively selected. These patients had received two different types of microimplant-assisted maxillary expansion treatment (MARPE and BAME). The patient underwent Cone-Beam computed tomography (CBCT) before and after treatment (mean time 1.5 months) with MARPE or BAME and upper airway measurements (volume and minimum cross-sectional area) were taken to assess upper airways changes and compare changes between the groups. A paired sample t-test was performed to evaluate the T0-T1 change of airway measurements obtained with MARPE and BAME, and a student t-test to compare changes in airway measurements between MARPE and BAME.

RESULTS

This investigation shows a statistically significant increase in total nasopharyngeal airway volume (0.59 ± 1.42 cm3; p < 0.01), total oropharyngeal airway volume (3.83 ± 7.53 cm3; p < 0.01) and minimum oropharyngeal cross-section (53.23 ± 126.46 mm2; p < 0.05) in all cases treated with micro-screw assisted expansion. The minimal cross-sectional area of the oropharynx ((79.12 ± 142.28 mm2; p < 0.05) and hypopharynx (59.87 ± 89.79 mm2; p < 0.05) showed significant changes for cases treated with BAME. As for the comparison between cases treated with MARPE and BAME, no differences in upper airway changes have been observed, except for the minimum cross-sectional area of the nasal cavity, which increases for MARPE (52.05 ± 132.91 mm2) and decreases for BAME (-34.10 ± 90.85 mm2).

CONCLUSIONS

A significant increase in total area and minimal section at the level of nasopharynx and oropharynx was observed in cases treated with BAME. Regarding the comparison of MARPE and BAME treatments, no differences were found in the total airway volume and minimal section in upper airway except for the minimum cross section of the nasal cavity that increases for MARPE and decreases for BAME.

What changes in maxillary morphology from distraction osteogenesis maxillary expansion (DOME) correlate with subjective and objective OSA measures?

OBJECTIVES

To correlate skeletal and airway measures on imaging with polysomnographic and self-reported measures after distraction osteogenesis maxillary expansion (DOME), in the effort to identify clinically relevant sites of expansion to guide treatment for adult patients with obstructive sleep apnea (OSA).

MATERIALS AND METHODS

This is a retrospective study reviewing subjects who underwent DOME and had the complete set of the following data: peri-treatment cone-beam computed tomography (CBCT) scans, polysomnography (PSG), Epworth Sleepiness Scale (ESS), and nasal obstruction symptom (NOSE) scores.

RESULTS

Of 132 subjects who underwent DOME, 35 met inclusion criteria (71% men, mean age 27.7 ± 6.5 years, mean BMI 26.0 ± 6.4 kg/m2) and were enrolled in the study. There was a significant reduction in the NOSE score from 11.4 ± 5.5 to 3.6 ± 3.1, in the ESS score from 12.0 ± 4.6 to 7.1 ± 4.7, and in the apnea-hypopnea index (AHI) from 17.1 ± 15.8 to 7.01 ± 6.2 (p < 0.0001), after DOME. Nasal floor width at the nasopalatine canal level showed a statistically significant correlation with AHI reduction (p < .0001).

CONCLUSIONS

DOME is significantly associated with reduction of nasal obstruction, sleepiness, and severity of OSA. The findings suggest that expansion at the anterior third of the bony nasal passage, specifically where the nasopalatine canal is located predicts its clinical efficacy. This site may be a useful target anatomically via imaging.

Pattern of microimplant displacement during maxillary skeletal expander treatment: A cone-beam computed tomography study

Objective

To analyze the microimplant (MI) displacement pattern on treatment with a maxillary skeletal expander (MSE) using cone-beam computed tomography (CBCT).

Methods

Thirty-nine participants (12 males and 27 females; mean age, 18.2 ± 4.2 years) were treated successfully with the MSE II appliance. Their pre- and post-expansion CBCT data were superimposed. The pre- and post-expansion anterior and posterior inter-MI angles, neck and apical inter-MI distance, plate angle, palatal bone thickness at the MI positions, and suture opening at the MI positions were measured and compared.

Results

The jackscrew plate was slightly bent in both anterior and posterior areas. There was no significant difference in the extent of suture opening between the anterior and posterior MIs (p > 0.05). The posterior MI to hemiplate line was greater than that anteriorly (p < 0.05). The apical distance between the posterior MIs was greater than that anteriorly (p < 0.05). The palatal thickness at the anterior MIs was significantly greater than that posteriorly (p > 0.01).

Conclusions

In the coronal plane, the angulation between the anterior MIs in relation to the jackscrew plate was greater than that between the posterior MIs owing to the differential palatal bone thickness.

Monitoring the Opening of Rapid Palatal Expansion (RPE) in a 3D-Printed Skull Model Using Fiber Optic F-P Sensors

We present a novel method for the online measurement of multi-point opening distances of midpalatal sutures during a rapid palatal expansion (RPE) using fiber optic Fabry-Perot (F-P) sensors. The sensor consists of an optical fiber with a cut flat end face and an optical reflector, which are implanted into the palatal base structure of an expander and is capable of measuring the precise distance between two optical reflective surfaces. As a demonstration, a 3D-printed skull model containing the maxilla and zygomaticomaxillary complex (ZMC) was produced and a miniscrew-assisted rapid palatal expander (MARPE) with two guide rods was used to generate the midpalatal suture expansion. The reflected spectrums of the sensors were used to dynamically extract cavity length information for full process monitoring of expansion. The dynamic opening of the midpalatal suture during the gradual activation of the expander was measured, and a displacement resolution of 2.5 μm was demonstrated. The angle of expansion was derived and the results suggested that the midpalatal suture was opened with a slight V-type expansion of 0.03 rad at the first loading and subsequently expanded in parallel. This finding might be useful for understanding the mechanical mechanisms that lead to different types of expansion. The use of a fiber optic sensor for mounting the rapid palatal expander facilitates biomechanical studies and experimental and clinical evaluation of the effects of RPE.

Class III treatment with mini-implants anchorage in young adult patients: short and long-term results

INTRODUCTION

Class III malocclusion should be intercepted and treated at early age, to prevent the necessity of future complex and expensive procedures. The orthopedic facemask therapy has the goal to achieve skeletal changes, minimizing side effects on dentition. The use of skeletal anchorage, combined with Alternate Rapid Maxillary Expansion and Constriction (Alt-RAMEC) protocol, may be effective in treating a greater number of growing Class III patients.

OBJECTIVE

To summarize the existing evidence-based literature on Class III malocclusion treatment in young adult patients, and to illustrate its application and effectiveness, by presenting an emblematic case report.

CONCLUSION

The resolution of the present case, its long-term follow up, along with the studies conducted on a larger sample, demonstrate the effectiveness of the strategic combination of orthopedic and orthodontic treatments by using an hybrid rapid palatal expander and Alt-RAMEC protocol for treating Class III malocclusions in adult patients.

Do the miniscrews of the prefabricated systems for the "appliance first" protocol of miniscrew-assisted rapid palatal expansion have lengths that meet the palatal thickness of patients?

INTRODUCTION

In the "appliance first" protocol of miniscrew-assisted rapid palatal expansion, the prefabricated shape of the expanders limits the potential locations for miniscrew placement. Considering the influence of palatal thickness on the selection of the optimal length of miniscrews, this study aimed to evaluate the thickness of both bone and mucosa of the palate of patients aged 6-65 years and suggest optimal lengths of miniscrews for this approach.

METHODS

Two hundred and eighty-two cone-beam computed tomography of patients of both sexes were divided into 3 groups according to age. The thicknesses of bone and mucosa were measured in the anterior and posterior regions of the palate.

RESULTS

Males showed a greater thickness of palatal bone than females. The thickness of both bone and mucosa was greater in the anterior region of the palate. The young patients showed greater bone thickness than adults and mature adults. The mature adults showed thinner bone thickness in the posterior region of the palate and greater mucosal thickness along the palate than young patients and adults. Development of miniscrews with longer thread lengths is necessary. Miniscrews with a 3-mm thread length would prevent excessive extravasation in the posterior region of the palate.

CONCLUSIONS

The thickness of both bone and mucosa of the palate is variable and influenced by sex and age. Manufacturing additional miniscrews with different lengths of thread is suggested to achieve bicortical anchorage in patients undergoing the "appliance first" protocol of miniscrew-assisted rapid palatal expansion.

[Study on quantitative analysis of bracket-induced nonlinear response of labio-cheek soft tissue during the orthodontic process]

In the orthodontics process, intervention and sliding of an orthodontic bracket during the orthodontic process can arise large response of the labio-cheek soft tissue. Soft tissue damage and ulcers frequently happen at the early stage of orthodontic treatment. In the field of orthodontic medicine, qualitative analysis is always carried out through statistics of clinical cases, while quantitative explanation of bio-mechanical mechanism is lacking. For this purpose, finite element analysis of a three-dimensional labio-cheek-bracket-tooth model is conducted to quantify the bracket-induced mechanical response of the labio-cheek soft tissue, which involves complex coupling of contact nonlinearity, material nonlinearity and geometric nonlinearity. Firstly, based on the biological composition characteristics of labio-cheek, a second-order Ogden model is optimally selected to describe the adipose-like material of the labio-cheek soft tissue. Secondly, according to the characteristics of oral activity, a two-stage simulation model of bracket intervention and orthogonal sliding is established, and the key contact parameters are optimally set. Finally, the two-level analysis method of overall model and submodel is used to achieve efficient solution of high-precision strains in submodels based on the displacement boundary obtained from the overall model calculation. Calculation results with four typical tooth morphologies during orthodontic treatment show that: ① the maximum strain of soft tissue is distributed along the sharp edges of the bracket, consistent with the clinically observed profile of soft tissue deformation; ② the maximum strain of soft tissue is reduced as the teeth align, consistent with the clinical manifestation of common damage and ulcers at the beginning of orthodontic treatment and reduced patient discomfort at the end of treatment. The method in this paper can provide reference for relevant quantitative analysis studies in the field of orthodontic medical treatment at home and abroad, and further benefit to the product development analysis of new orthodontic devices.

Evaluation of palate-related factors of the effectiveness of microimplant-assisted rapid palatal expansion in late adolescents and adults

INTRODUCTION

This study investigated the factors of the effectiveness of microimplant-assisted rapid palatal expansion (MARPE) in late adolescents and adults, such as age, midpalatal suture maturation (MPSM) stage, palate length (PL), palatal index (PI), and midpalatal bone thickness (MBT), and at each microimplant position, the palate bone thickness (PBT), the nasal cortical bone thickness (CoTN), the cancellous bone thickness (CaT), and the palate cortical bone thickness (CoTP) were evaluated.

METHODS

Cone-beam computed tomography (CBCT) images of 50 patients (mean, 23.30 ± 7.03 years; range, 16-51 years) treated with MARPE were evaluated. Maxillary expansion ratio (MER) was used to assess the MARPE effectiveness and grouped patients into low and high MER groups according to the mean of MER. MER was the ratio of maxillary expansion width to MARPE screw expansion measured in CBCT images. The t-test was used to analyze the differences between the low and high MER groups. The Pearson correlation test was performed to investigate the correlation between MER and age, MPSM stage, PL, PI, MBT, PBT, CoTN, CaT, and CoTP.

RESULTS

Age, MPSM stage, and MBT in regions 18 mm and 21 mm behind the incisor foramen correlated negatively with MER ([Formula: see text], - 0.390, - 0.386, and - 0.335, respectively, all [Formula: see text]), whereas PBT and CoTN of anterior microimplant positions correlated positively with MER ([Formula: see text] and 0.418, respectively, all [Formula: see text]). No correlation was observed between other variables and MER.

CONCLUSIONS

MARPE effectiveness decreased as age and midpalatal suture maturation stage increased, respectively. Thinner midpalatal suture bone in regions 18 mm and 21 mm behind the incisor foramen, thicker palate bone, and nasal cortical bone of anterior microimplant positions were related to more effective MARPE.

CLINICAL RELEVANCE

In patients with older chronological age and later MPSM stages, MARPE effectiveness might be unsatisfactory. Clinicians should carefully evaluate the palate bone thickness before MARPE treatment.

Comparison of 3 different bone-borne type expansion appliances used in surgically-assisted rapid palatal expansion: A finite element analysis

INTRODUCTION

This study aimed to compare the effects of 3 different bone-borne type expansion appliances used in the surgically-assisted rapid palatal expansion (SARPE) by finite element analysis.

METHODS

Three different miniscrew-supported palatal expansion appliances were modeled. Median and lateral osteotomies were performed without pterygomaxillary suture separation. Model I consisted of a palatal expander with 2 miniscrews placed 4 mm far from the midpalatal suture. In model II, 2 miniscrews were located at the alveolar ridge between the first molar and the second premolar. In model III, 4 miniscrews were placed as a combination of the first and second models. Stress distributions and amount of displacements were evaluated with Ansys software (version 19.2; Ansys, Canonsburg, Pa) for 5-mm expansion in a symmetrical finite element analysis model to reflect the clinical situation.

RESULTS

SARPE simulation using miniscrew-assisted maxillary expanders for all models showed a rotation and tipping of the maxilla. The largest displacement was found for the anterior part of the palate in model II and the posterior part in model III. Although a wedge-shaped expansion pattern was observed in all models, this form was more prominent in model II. The highest stress value (0.91 MPa) was measured in model I, and the lowest value (0.004 MPa) was measured in model II for the anterior nasal spine region. The highest stress value (0.51 MPa) was measured in model III, and the lowest value (0.12 MPa) was measured in model II for the posterior nasal spine region. The lowest stress values were measured in model II for all the craniofacial and maxillofacial structures.

CONCLUSIONS

Among the models, the lowest stress distribution conditions for craniofacial and maxillofacial structures were found in model II. The largest displacement was found at the incisors and anterior part of the maxilla for model II. The greatest displacement was found at the posterior region for model III.

Analysis of factors associated with the success of microimplant-assisted rapid palatal expansion

INTRODUCTION

Success-related factors of microimplant-assisted rapid palatal expansion (MARPE) were evaluated, including age, palatal depth, suture, and parassutural bone thickness, suture density and maturation, and the relation to corticopuncture (CP) technique, as well as skeletal and dental effects.

METHODS

Sixty-six cone-beam computed tomography scans were analyzed before and after rapid maxillary expansion procedures in 33 patients aged 18-52 years for both sexes. The scans were generated in digital imaging and communications in medicine file format and analyzed in the multiplanar reconstruction of the regions of interest. Palatal depth, suture thickness, density and maturation, age, and CP were assessed. To evaluate dental and skeletal effects, the sample was divided into 4 groups: successful MARPE (SM), SM + CP technique (SMCP), failure MARPE (FM), and FM + CP (FMCP).

RESULTS

Successful groups presented more skeletal expansion and dental tipping than failure groups (P <0.05). The mean age of the FMCP group was significantly higher than the SM groups; suture and parassutural thickness significantly related to the success, and patients who received CP showed a success rate of 81.2% compared with 33.3% in the no CP group (P <0.05). Suture density and palatal depth did not show a difference between the success and failure groups. Suture maturation was higher in SMCP and FM groups (P <0.05).

CONCLUSIONS

Older age, thin palatal bone, and higher stage of maturation can influence the success of MARPE. CP technique in these patients appears to have a positive impact, increasing the chance of treatment success.

Condylar morphology and position changes after miniscrew-assisted rapid palatal expansion in skeletal Class III malocclusion adult patients with mandibular deviation and unilateral posterior crossbite

BACKGROUND

To evaluate the morphological and positional changes of mandibular condyle after miniscrew-assisted rapid palatal expansion (MARPE) in skeletal Class III malocclusion adult patients with horizontal mandibular deviation (MD).

METHODS

The sample consisted of 15 patients with MD (6 males and 9 females, mean age 21.58 ± 3.12 years). The CBCT scans were taken before and after MARPE immediately. The pre- and post-registered images of the cranial base and mandible were measured, respectively, by Mimics.

RESULTS

After expansion, the distance between superior condylar point and the Frankfort horizontal plane on the deviated side and the non-deviated side increased by 0.96 ± 0.60 mm (P = 0.011) and 0.70 ± 0.65 mm (P = 0.046); coronal condylar angle of the deviated side increased by 0.39° ± 0.34 (P = 0.028) and 0.06° ± 0.49 (P = 0.917) on the non-deviated side. No statistically significant differences were found when comparing the condylar position on both sides before and after treatment. The degree of mandibular deviation decreased 0.43 mm (P = 0.270).

CONCLUSIONS

This study suggested that for skeletal Class III malocclusion adult patients with horizontal MD, the condyle on the deviated side rotated toward the non-deviated side in the coronal direction; the condylar remodeling occurred mainly on the deviated side after MARPE in the vertical direction.

Management of Class III Malocclusion and Maxillary Transverse Deficiency with Microimplant-Assisted Rapid Palatal Expansion (MARPE): A Case Report

Microimplant-assisted rapid palatal expansion (MARPE) has been demonstrated successfully in maxillary expansion in late adolescence and adulthood. The maxillary advancement accompanied by expansion is frequently anticipated, which is beneficial for the treatment of class III malocclusion. Airway volume increase can also be noted in some cases from the measurement of cone beam computerized tomography (CBCT) after expansion. The objective of this case report is to demonstrate the feasibility of applying MARPE on late adolescence patients with maxillary transverse deficiency and to present the changes in transverse and anteroposterior dimensions as well as the volume increase in velopharyngeal airway after MARPE. A 15-year-old female presented class III skeletal pattern. She had maxillary transverse deficiency with moderate crowding and posterior/anterior crossbites. Maxillary Skeletal Expander (MSE; Biomaterials Korea Inc.) type-2 was used as a MARPE device in this case. After four weeks of maxillary expansion, a significant amount of expansion was achieved and the anterior crossbite was spontaneously corrected. Fixed appliance treatment was commenced four weeks after MARPE with 0.022-slot preadjusted brackets (MBT prescription). Temporary anchorage devices (TADs) were placed over the mandibular buccal shelves for posterior teeth distalization and crowding relief. After 25 months of treatment, the facial profile was improved with maxillary advancement (SNA: 83° to 83.5°) and mandibular backward rotation (SNB: 83° to 82°; SN-MP: 34.5° to 35°). In this case, MARPE not only engenders significant transverse correction but also aids in anteroposterior change. The treatment effects of maxillary advancement and mandibular backward rotation can lead to a more esthetic profile in skeletal class III cases.

Evaluation of changes in orbital volume in adult female patients with maxillary transverse deficiency treated with a maxillary skeletal expander

OBJECTIVES

The effects of using a maxillary skeletal expander (MSE) on the orbital volume and width between periorbital bones in the treatment of adult female patients with maxillary transverse deficiency (MTD) were evalua⁃ted.

METHODS

A total of 20 adult female patients with MTD with an average age of (22.60±6.29) years were included in the study. The patients were treated with MSE. Cone beam computed tomography was performed before expansion (T0) and no more than 3 weeks after expansion (T1). Orbital volume and periorbital bone width were measured with Mimics 21.0 and analyzed with SPSS 20.0. Paired t-test was performed, and a P value of <0.05 indicated significant difference.

RESULTS

After expansion, the orbital volume increased by (346.80±275.31) mm3 (P<0.05). The width between the right and left zygomaticomaxillary sutures increased by (1.69±0.57) mm (P<0.05), and the width between the right and left infraorbital points increased by (1.71±0.70) mm (P<0.05). However, the width between the right and left frontozygomatic sutures increased by (0.15±0.32) mm (P>0.05). Finally, the width between the right and left supraorbital points increased by (0.23±0.52) mm (P>0.05).

CONCLUSIONS

The maxillary skeletal expander slightly expanded the orbital volume in the adult female patients and increased the lateral widths of the periorbital bones.

Procedure using CAD/CAM-manufactured insertion guides for purely mini-implant-borne rapid maxillary expanders

With traditional rapid palatal expansion (RPE), orthopaedic forces are transmitted to the skeletal structures via the anchor teeth potentially leading to several unwanted dental side effects. To prevent these issues, tooth–bone-borne or purely bone-borne expanders were introduced using mini-implants in the palate. In this paper, the digitally planned Quadexpander is described which permits palatal expansion with only skeletal anchorage. The use of virtual insertion planning allows for insertion in areas of ideal bone, while avoiding roots and vital structures as well as the possibility of insertion into sites which would otherwise not be considered usable. A second advantage of digital planning is that mini-implants and the expander can be inserted in just one appointment.

Three-dimensional craniofacial changes with maxillary expansion in young adult patients with different craniofacial morphology

Objectives:

Skeletally mature patients with transverse deficiency are best treated with surgically assisted rapid palatal expansion (RPE) procedure. Recent studies have shown that microimplant-assisted RPE (MARPE) appliances can be effective in achieving skeletal expansion in young adults. This retrospective study aimed to evaluate the skeletal and dental alveolar changes in response to treatment with MARPE appliances in three types of anteroposterior skeletal malocclusions using cone-beam computed tomography (CBCT) scans.

Material and Methods:

Seventy-eight subjects diagnosed with maxillary transverse deficiency and treated with the MARPE appliance (mean age of 22.9 ± 4.2 years) were divided into skeletal Class I, II, and III malocclusions with 26 subjects in each group. Pre- and post-treatment CBCT scans were used for superimposition to examine the skeletal and dentoalveolar changes following maxillary expansion treatment.

Results:

Significant lateral separation of the maxilla was found at the levels of the nasal floor, interzygomatic bones, and the inferior palatine margin of the alveolar process (P < 0.05) in the whole sample. Most of the sagittal and vertical variables change significantly in the whole sample and each studied group separately. Intergroup comparisons revealed no significant differences among the three skeletal classes except for the left frontozygomatic angle, left maxillary inclination angle, and torque in the first and second premolars. In Class III patients, the maxilla moved forward significantly in most of the cases (eight of 26 cases) (0.88°, P < 0.05) and the mandible moved downward and backward improving the anteroposterior skeletal relationship. Significant differences were also found in the vertical measurements (N-Me, MMP, and MP/SN, P < 0.05) in all three types of anteroposterior malocclusions.

Conclusion:

Maxillary expansion with the MARPE appliance in young adult patients induced different skeletal and dentoalveolar changes in the anteroposterior and vertical dimensions in each skeletal malocclusion with no significant difference among the three skeletal classes.

Can gray values be converted to Hounsfield units? A systematic review

OBJECTIVES

The purpose of this systematic review was to answer the focus question: "Could the gray values (GVs) from CBCT (cone beam computed tomography) be converted to Hounsfield units (HUs) in multidetector computed tomography (MDCT)?"

METHODS

The included studies try to answer the research question according to the PICO strategy. Studies were gathered by searching several electronic databases and partial grey literature up to January 2021 without language or time restrictions. The methodological assessment of the studies was performed using The Oral Health Assessment Tool (OHAT) for in vitro studies and the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) for in vivo studies. The Grading of Recommendations Assessment, Development and Evaluation (GRADE system) instrument was applied to assess the level of evidence across the studies.

RESULTS

2710 articles were obtained in Phase 1, and 623 citations remained after removing duplicates. Only three studies were included in this review using a two-phase selection process and after applying the eligibility criteria. All studies were methodologically acceptable, although in general terms with low risks of bias. There are some included studies with quite low and limited evidence estimations and recommendation forces; evidencing the need for clinical studies with diagnostic capacity to support its use.

CONCLUSIONS

This systematic review demonstrated that the GVs from CBCT cannot be converted to HUs due to the lack of clinical studies with diagnostic capacity to support its use. However, it is evidenced that three conversion steps (equipment calibration, prediction equation models, and a standard formula (converting GVs to HUs)) are needed to obtain pseudo Hounsfield values instead of only obtaining them from a regression or directly from the software.

MARPE as an adjunct to orthodontic treatment

Introduction:

Miniscrew or microimplant-assisted rapid palatal expansion (MARPE) devices are used to achieve a skeletal expansion of the palate and to increase the arch perimeter.

Objective:

To describe the treatment of a 23-year-old woman with an Angle Class II, division 1 malocclusion with constricted maxillary and mandibular arches.

Case report:

The patient’s main complaint was mandibular anterior crowding. The treatment plan included expansion of the mandibular arch concurrent with maxillary expansion, using a MARPE appliance in combination with a full-fixed appliance to align and level the crowded mandibular teeth, along with miniscrews as anchorage for the maxillary teeth and for distalization of the molars and premolars. A successful non-extraction orthodontic treatment was accomplished after 28 months, and the occlusion and teeth alignment, as well as facial goals, were resolved in a clinically satisfactory manner.

Conclusion:

The treatment objectives were met, and the outcome of the expansion of the maxillary arch with a MARPE appliance as an adjunct to a fixed appliance was considered a success. An esthetic, functional, and stable result after a 1-year follow-up was achieved and was satisfactory to the patient.

Age-dependent effects of transverse maxillary deficiency treated by microimplant-assisted rapid palatal expansion: A prospective cone-beam computed tomography study

INTRODUCTION

This study investigated the results of maxillary discrepancy treated by microimplant-assisted rapid palatal expansion (MARPE) at different ages.

METHODS

Sixty patients (aged 11.0-34.1 years; 23 male and 37 female) were treated by MARPE. Cone-beam computed tomography scans and dental casts were taken before and after expansion. The data were compared among 4 age groups: early adolescents (aged 11-14 years), late adolescents (aged 15-19 years), young adults (aged 20-24 years), and old adults (aged 25-34.1 years).

RESULTS

The success rates of midpalatal suture separation were 100%, 100%, 88.2%, and 85.7% for early adolescents, late adolescents, young adults, and old adults, respectively. Palatal sutures at the level of the first molar were expanded by 4.02 mm, 3.48 mm, 2.63 mm, and 2.10 mm, corresponding to 66.7%, 58.1%, 42.0%, and 37.9% of the total dental expansion. Significant differences were found in the amounts of palatal suture expansion and the ratio of skeletal dental expansion between patients aged <20 years and patients aged ≥20 years (P <0.05). Skeletal expansion constituted 69.4%, 51.3%, 39.0%, and 29.8% of the total screw expansion. Except for the comparison between young adults and old adults, there were significant differences between groups for the ratio of skeletal screw expansion (P <0.05).

CONCLUSIONS

The midpalatal suture can be expanded by MARPE more easily in patients <20 years of age than in patients ≥20 years of age. The ratio of skeletal screw expansion decreases as age increases.

Dentoskeletal changes and their correlations after micro-implant-assisted palatal expansion (MARPE) in adults with advanced midpalatal suture ossification

OBJECTIVES

To evaluate and correlate the dentoskeletal changes of adult patients after miniscrew-assisted rapid palatal expander (MARPE) in the two final stages of midpalatal suture ossification.

MATERIALS AND METHODS

This interventional pre-post clinical study consisted of 20 adults (24.9±1.8 years), with transverse maxillary atresia, divided into two subgroups (n=10) based on the ossification degree of the midpalatal suture: stage D, fusion completed in the palatine bone; and stage E, fusion anteriorly in the maxilla. Cone beam computed tomography (CBCT) in the pre- (T₀) and post-treatment (T₁) time intervals were used to evaluate the anterior and posterior sutural opening, activation of the expander screw, vestibular-lingual inclinations, and widths of first premolars and first molars. Maxillary interincisor diastema was measured on patients' plaster models in the same timepoints. The Wilcoxon-Mann-Whitney test, generalized linear models (GLM), and chi-square (χ²) test were employed.

RESULTS

All variables significantly increased after MARPE therapy regardless of the ossification degree (P<0.05). Patients with stage D suture presented wider interincisal diastema and maxillary suture opening (on both regions, anterior and posterior) when compared with patients with stage E (P<0.05). Maxillary interincisor diastema was positively associated with anterior and posterior suture opening for all subjects (P<0.05). MARPE therapy was unsuccessful in six patients, mostly presented by individuals with E maturation stage of the midpalatal suture.

CONCLUSIONS

After MARPE, a significant correction in the transverse defect of the maxillary basal bone was achieved for adults in the last two midpalatal suture maturation stages.

CLINICAL RELEVANCE

Adult patients in stage D of maxillary suture ossification are more susceptible to dentoskeletal changes following MARPE therapy as compared to patients with stage E.

Digital Planning and Manufacturing of Maxillary Skeletal Expander for Patients with Thin Palatal Bone

The miniscrew-assisted rapid palatal expansion approach has given new opportunities for the treatment of maxilla transverse deficiency by providing an alternative to the surgical approach for adult patients. However, the presence of a thin palatal bone can compromise the success of such approach. Recently, the digital planning of the miniscrew-assisted appliances has offered unique advantages in terms of safety and accuracy of the overall process. The aim of this study is to describe the digital planning and MSE fabrication with cad-cam technology using 6 mini-screws in cases with a palatal bone thickness of less than 2.5 mm.

A Simplified Digital Approach to the Treatment of a Postpuberty Patient with a Class III Malocclusion and Bilateral Crossbite

Monolateral and bilateral crossbites are amongst the most frequent forms of malocclusion in the world population. The lack of early correction of this type of malocclusion leads to the partial or total ossification of the sutures which then require surgical treatment in adult patients. In recent years, devices on minipalatal screws have noticeably increased the time window in which it is possible to correct these types of alterations. In this case report, we show how it is possible to correct a third-class skeletal malocclusion associated with a posterior bilateral crossbite in a young woman using a rapid expander on miniscrews and fixed orthodontic device to finalise the process. The procedure for the insertion of the palatal screws was aided by the use of a digitally printed surgical guide, and the appliance was applied in the same sitting thanks to the use of a digital flow software and a systematic easy driver. The CBCT scans show how the orthopaedic expansion of the upper maxilla was obtained without any important alterations that damaged the permanent teeth. This case report wishes to demonstrate how easy and predictable it can be to resolve cases of this type with optimal aesthetic and functional results even when body growth has ended.

Stress and displacement of mini-implants and appliance in Mini-implant Assisted Rapid Palatal Expansion: analysis by finite element method

Objective:

In this study, simulations were performed by the finite element method (FEM) to determine the tension and displacement in mini-implants and in expander appliance during rapid maxillary expansion, by varying the number and location of the mini-implants.

Methods:

For the computational simulation, a three-dimensional mesh was used for the maxilla, mini-implants and expander appliance. Comparisons were made on six different Mini-implant Assisted Rapid Palatal Expander (MARPE) configurations, by varying the amount and location of mini-implants. A closed suture was design and received two activations of 0.25 mm, and an open suture had a 0.5-mm aperture that received 20 activations, also of 0.25 mm.

Results:

For the closed suture, the maximum displacement values in the mini-implants were between 0.253 and 0.280 mm, and stress was between 1,348.9 and 2,948.2 MPa; in the expander appliance, the displacement values were between 0.256 and 0.281 mm, and stress was between 738.52 and 1,207.6 MPa. For the open suture, the maximum displacement values in the mini-implants were between 2.57 and 2.79 mm, and stress was between 5,765.3 and 10,366 MPa; in the appliance, the maximum displacements was between 2.53 and 2.89 mm, and stress was between 4,859.7 and 9,157.4 MPa.

Conclusions:

There were higher stress concentrations in the mini-implant than in the expander arm. In the simulations with a configuration of three mini-implants, stress overload was observed in the isolated mini-implant. Displacements of the mini-implants and arms of the appliance were similar in all simulations.

Intraperitoneal injection of PDTC on the NF-kB signaling pathway and osteogenesis indexes of young adult rats with anterior palatal suture expansion model

In recent years, many studies have found that mechanical tension can activiate NF-kB signal pathway and NF-kB plays an important role in the process of osteogenesis. However, it is still unclear whether this process exists in the anterior palatal suture expansion. In this paper, we mainly studied the effect of intraperitoneal injection of PDTC on the NF-kB signaling pathway and osteogenesis index of the anterior palatal suture expansion model in young adult rats. The expansion model is grouped and established: 45 male 8-week-old Sprague-Dawley rats were randomly divided into three groups, an expansion only (EO) group, an expansion plus PDTC (PE) group, and a control group. The results revealed that PDTC inhibited the activity of NF-kB signaling pathway and promote one morphogenetic protein 2 (BMP-2), steocalatin (OCN) expression. Compared with the control group, the optical density (OD) value of BMP in the EO group and PE group rats increased significantly from the first day to the seventh day, and the difference was statistically significant (P<0.05). After 6.0Gy irradiation, PDTC administration group could slightly increase the total SOD level in the liver and serum of rats, and reduce the MDA level in the liver and serum, especially the effect of 60mg/kg and 90mg/kg was the most obvious.

The prevalence of posterior tongue tie in patients with transverse maxillary deficiency

Objectives

To investigate the prevalence of posterior tongue tie in orthodontic patients using numerical and clinical assessment methods in order to identify an association between posterior tongue tie and transverse maxillary deficiency.

Materials and methods

Seventy-nine participants from an orthodontic clinic were divided into two groups. The first group of 44 patients exhibited a skeletally narrow maxilla and required maxillary skeletal expansion (MSE group) and 35 patients without a transverse discrepancy comprised a control group. Posterior tongue tie was examined by the Kotlow tongue tie classification, tongue range of motion ratio (TRMR) and via a clinical assessment. The prevalence of posterior tongue tie was compared between the two groups.

Results

There was no significant difference in the level of the Kotlow classification grade between the two groups (p > 0.05) and the overall majority was diagnosed as normal. However, a higher proportion of posterior tongue tie was found in the MSE group than in the control group by clinical assessment (MSE group, 72.7%; control group, 42.9%; p = 0.005). The proportion of TRMR grade 2 was also higher in the MSE group than in the control group (p = 0.001). Of the subjects diagnosed with posterior tongue tie by clinical findings, approximately 94% showed TRMR grades 2 or 3.

Conclusions

A clinical assessment of posterior tongue tie was found to be simple and accurate, whereas a numerical assessment alone provided diagnostic difficulty. Considering the high prevalence of observed posterior tongue tie in the MSE group, there was a significant association between posterior tongue tie and transverse maxillary deficiency.

Stress distribution and displacement of three different types of micro-implant assisted rapid maxillary expansion (MARME): a three-dimensional finite element study

Abstract

Background/objective

Until 2010, adults underwent surgical treatment for maxillary expansion; however, with the advent of micro-implant-assisted rapid maxillary expansion (MARME), the availability of less invasive treatment options has increased. Nevertheless, individuals with severe transverse maxillary deficiency do not benefit from this therapy. This has aroused interest in creating a new device that allows the benefit of maxillary expansion for these individuals. The aim of this study was to evaluate the efficacy of three MARME models according to tension points, force distribution, and areas of concentration in the craniofacial complex when transverse forces are applied using finite element analysis.

Materials and methods

Digital modeling of the three MARME models was performed. Model A comprised five components: one body screw expander and four adjustable arms with rings for mini-implant insertion. These arms have an individualized height adjustment that allows MARME positioning according to the patient’s palatal anatomy, thereby preventing body screw expander collision with the lateral mucosa in severe cases of maxillary deficiency. Model B was a maxillary expander with screw rings joined to the body, and model C was similar to model B, except that model C had open rings for the insertion of the mini-implants. Through the MEF (Ansys software), the stresses, distribution, and area of concentration of the stresses were evaluated when transverse forces of 7.85 N were applied.

Results

The three models maintained the following pattern: model C presented weak stress peaks with limited distribution and lower concentration area, model B obtained median stress peaks with better distribution when compared to that of model C, and model A showed better stress distribution and larger concentration area. In model A, tensions were located in the lateral lamina of the pterygoid process, which is an important site for maxillary expansion. The limitation of the present study was that it did not include the periodontal tissues and muscles in the finite element method evaluation.

Conclusions

Model A showed the best stress distribution conditions. In cases of severe atresia, model A seems to be an excellent option.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40510-021-00357-5.

Effect of Different Head Hole Position on the Rotational Resistance and Stability of Orthodontic Miniscrews: A Three-Dimensional Finite Element Study

The orthodontic miniscrew is driven into bone in a clockwise direction. Counter-clockwise rotational force applied to the implanted miniscrew can degrade the stability. The purpose of this three-dimensional finite element study was to figure out the effect of shifting the miniscrew head hole position from the long axis. Two miniscrew models were developed, one with the head hole at the long axis and the other with an eccentric hole position. One degree of counter-clockwise rotation was applied to both groups, and the maximum Von-Mises stress and moment was measured under various wire insertion angles from −60° to +60°. All Von-Mises stress and moments increased with an increase in rotational angle or wire insertion angle. The increasing slope of moment in the eccentric hole group was significantly higher than that in the centric hole group. Although the maximum Von-Mises stress was higher in the eccentric hole group, the distribution of stress was not very different from the centric hole group. As the positive wire insertion angles generated a higher moment under a counter-clockwise rotational force, it is recommended to place the head hole considering the implanting direction of the miniscrew. Clinically, multidirectional and higher forces can be applied to the miniscrew with an eccentric head hole position.

Mesioangulation of mandibular second molars: A case report

This case report describes a simple alternative for treatment of mesioangulation of mandibular second molars. An 11-year-old girl was diagnosed with unilateral posterior crossbite, moderate incisor crowding and mesioangulation of the right mandibular second molar. The ectopic second molar was uprighted using a modified lingual arch with a distal hook and elastic chains. Orthodontic traction began after appliance installation and was activated once per month using 120 g of force. After six months, the right mandibular second molar was in an upright position. Orthodontic treatment continued with teeth levelling and alignment until acceptable occlusal and aesthetic results were achieved. Adequate stability was observed one year after debonding. The modified mandibular lingual arch with a distal hook is a simple and effective alternative to manage mesioangulation of mandibular second molars with minimum adverse effects and stable outcomes.

Skeletal width changes after mini-implant-assisted rapid maxillary expansion (MARME) in young adults

OBJECTIVES

To observe skeletal width changes after mini-implant-assisted rapid maxillary expansion (MARME) and determine the possible factors that may affect the postexpansion changes using cone-beam computed tomography (CBCT) in young adults.

MATERIALS AND METHODS

Thirty-one patients (mean age 22.14 ± 4.76 years) who were treated with MARME over 1 year were enrolled. Four mini-implants were inserted in the midpalatal region, and the number of activations ranged from 40 to 60 turns (0.13 per turn). CBCT was performed before MARME (T0), after activation (T1), and after 1 year of retention (T2). The mean period between T1 and T0 was 6 ± 1.9 months and between T2 and T1 was 13 ± 2.18 months. A paired t-test was performed to compare T0, T1, and T2. The correlations between the postexpansion changes and possible contributing factors were analyzed by Pearson correlation analysis.

RESULTS

The widths increased significantly after T1. After T2, the palatal suture width decreased from 2.50 mm to 0.75 mm. From T1 to T2, decreases recorded among skeletal variables varied from 0.13 mm to 0.41 mm. This decrease accounted for 5.75% of the total expansion (2.26 mm) in nasal width (N-N) and 19.75% at the lateral pterygoid plate. A significant correlation was found between postexpansion change and palatal cortical bone thickness and inclination of the palatal plane (ANS-PNS/SN; P < .05).

CONCLUSIONS

Expanded skeletal width was generally stable after MARME. However, some amount of relapse occurred over time. Patients with thicker cortical bone of the palate and/or flatter palatal planes seemed to demonstrate better stability.

In-vitro trabecular bone damage following mono- and bicortical mini implants anchorage in mini-implant assisted rapid palatal expansion (MARPE)

OBJECTIVES

To assess in-vitro trabecular bone damage following mono- and bicortical mini-implant (MI) anchorage in mini-implant assisted rapid palatal expansion (MARPE).

MATERIAL AND METHODS

Sixteen self-drilling MI (four MARPE appliances) were distributed in two groups according to bone insertion (monocortical and bicortical) in bovine rib. The device was activated five times (0.5mm each). Trabecular bone damage was assessed using micro-CT scans made at baseline and after each activation by trabecular spacing parameter (Tb.Sp) (distance [mm] between the trabecular bone structure). These measurements were made in five different regions of interest (ROI) surrounding the screw (whole, superior, inferior, anterior and posterior). Two-way ANOVA with Tukey post-hoc analysis (α=0.05) was used to evaluate the effect of insertion type (monocortical vs. bicortical) and activation cycle (0-5) on trabecular damage. The time effect was evaluated using ANOVA-MR test effect with Bonferroni correction (α=0.003). The micro-CT images were also examined qualitatively.

RESULTS

When analysing the individual ROIs, only the superior ROI had a significant difference (P<0.003) beginning at the fourth activation cycle. For the monocortical group, trabecular spacing was affected when the whole ROI was analysed beginning at the fourth activation cycle, while for the superior ROI, this difference became apparent beginning with the third activation cycle (P<0.003). For the qualitative analysis, it seems that only monocortical anchorage influences the trabecular bone in the superior area.

CONCLUSIONS

Monocortical anchorage is more susceptible to bone damage around the MIs, with the superior (cervical) region most strongly affected.

Miniscrew-assisted rapid palatal expansion (MARPE): how to achieve greater stability. In vitro study

Objective:

Assess the influence of mono- and bicortical anchorage and diameter of mini-implants (MIs) on the primary stability of these devices.

Methods:

60 self-drilling MIs were distributed in six groups according to diameter (1.5mm, 1.8mm or 2.0mm) and type of anchorage (monocortical and bicortical) in bovine rib. The primary stability was evaluated by insertion torque, micromobility and pull-out strength tests. ANOVA and/or Tukey analysis were used to conduct intergroup comparisons (p< 0.05). Non-parametric statistics (Kruskal-Wallis and Mann-Whitney) were performed when normality was not found (p< 0.05).

Results:

MIs with larger diameters and bicortical anchorage showed greater primary stability regarding insertion torque (p< 0.05) and micromobility (p< 0.05). Only MI diameter had an effect on the pull-out strength test. Larger diameter MIs presented better retention in pull-out strength tests (p< 0.001), regardless of mono- or bicortical anchorage.

Conclusions:

MI primary stability is dependent on its diameter and type of anchorage. Bicortical anchorage showed greater stability when compared with monocortical anchorage, independently of other variables.

Evaluation of factors related to the success of miniscrew-assisted rapid palatal expansion

OBJECTIVES

To evaluate whether the success of miniscrew-assisted rapid palatal expansion (MARPE), performed in patients with advanced bone maturation is related to factors such as midpalatal suture (MPS) maturation, age, sex, or bicortical mini-implant anchorage.

MATERIALS AND METHODS

Twenty-eight cone beam computed tomography (CBCT) scans of adults and post-pubertal adolescents treated by MARPE were included in the sample. CBCT images before (T0) and after expansion (T1) were used to evaluate the skeletal changes and the success or failure of MARPE. Axial images of MPS were extracted from T0 and classified into one of the five maturation stages. The correlation between MARPE success and the factors of age, sex, MPS maturation, and bicortical mini-implant anchorage was investigated.

RESULTS

Only the age showed a statistically significant negative correlation with MARPE success and all the skeletal measures. There was an 83.3% success rate among individuals aged 15 to 19 years, 81.8% from 20 to 29 years, and 20% from 30 to 37 years. MPS maturation showed a negative correlation with the expansion effect. Subjects with stages B or C of MPS maturation showed a 100% success rate, followed by stage D (62.5%) and stage E (58.3%).

CONCLUSIONS

As age increased, there was a decrease in MARPE success and the skeletal effects of maxillary expansion. Sex and bicortical mini-implant anchorage were not shown to be relevant factors. There was no correlation between MPS maturation and MARPE success; however, it was observed that all cases of MARPE failure were classified as stage D or E of MPS maturation.

Effects of bicortical anchorage on pterygopalatine suture opening with microimplant-assisted maxillary skeletal expansion

INTRODUCTION

The objectives of this study were to evaluate the effects of bicortical engagement by microimplants with maxillary skeletal expanders on pterygopalatine sutures opening and to analyze the postexpansion skeletal changes associated with it.

METHODS

Eighteen subjects treated with maxillary skeletal expanders were examined for pterygopalatine suture openings. Eight subjects who showed no evidence of the suture opening were assigned to the nonsplit group (NG), whereas 10 subjects with opened sutures were assigned to the split group (SG). Preexpansion and postexpansion cone-beam computed tomography images were superimposed for each group, and the changes in the 2 groups were compared. Finally, cone-beam computed tomography volumes were reoriented along the axis of each microimplant to check the bicortical engagement of the 4 microimplants.

RESULTS

There was a significant correlation between the bicortical engagement of the orthodontic microimplants and the pterygopalatine suture opening (P = 0.0003). In the NG, the average amount of transverse expansion measured at the center of resistance of the maxillary first molars, anterior nasal spine, and posterior nasal spine (PNS) was 4.33 mm, 2.22 mm, and 1.58 mm, respectively, whereas the transverse expansion in the SG was 5.29 mm, 2.21 mm, and 2.46 mm, respectively. The magnitude of transverse expansion at PNS was significantly higher in the SG than in the NG (P = 0.036). The PNS also showed a significant anterior displacement in the SG (0.89 mm) compared with the NG (0.06 mm) (P = 0.033).

CONCLUSIONS

Bicortical microimplant anchorage is essential for pterygopalatine suture opening in microimplant-assisted maxillary skeletal expansion, which may result in further skeletal expansion and forward movement in the posterior part of the palatomaxillary complex.

Radiological evaluation of the bone and soft tissue thicknesses of the palate for using a miniscrew-supported maxillary skeletal expander

PURPOSE

The purpose of this study was to determine the palatal bone and soft tissue thicknesses using a miniscrew-supported maxillary skeletal expander (MSE) in Class III malocclusion.

METHODS

The thicknesses of the palatal bone and soft tissue were measured in cone-beam computed tomography images obtained from 58 patients. All 20 points were crossing points between five levels, which were defined at 3 mm intervals relative to the line connecting the central fossae of the first molar (Level 0), and 2 mm and 4 mm lateral to the anteroposterior reference line (AP line).

RESULTS

The palatal bone was significantly thicker in males than females in the anterior palate up to Level 0, while there was no significant sex-related difference in the posterior palate. There was a tendency for the thickness to decrease in the posterior direction, except in females at 2 mm lateral to the AP line. The palatal soft tissue was significantly thicker in males than females in all positions. At 2 mm lateral to the AP line, the palatal soft tissue thickness decreased in the posterior direction. A 4 mm lateral to the AP line, it initially decreased in the posterior direction, and then increasing again at Level - 6 (6 mm posterior of Level 0). As the lateral distance from the AP line increased, the palatal bone thickness decreased while the palatal soft tissue thickness increased.

CONCLUSIONS

These findings provide quantitative data on the palatal bone and soft tissue thicknesses for the miniscrew-supported MSE in the posterior palate.

The role of micro-implant-assisted rapid palatal expansion (MARPE) in clinical orthodontics — a literature review

A maxillary transverse deficiency is a common craniofacial problem. Rapid palatal expansion (RPE) has been traditionally considered for the treatment of children and young adolescents, but this is not applicable in late adolescents or adults due to the ossification of facial sutures. A surgically assisted rapid palatal expansion (SARPE) was initially advocated for this group of patients, but the surgical procedure is associated with morbidity. As temporary anchorage devices (TADs) have been recently and popularly applied in clinical orthodontics, micro-implant-assisted rapid palatal expansion (MARPE) has been employed to facilitate maxillary expansion in skeletally mature patients. There have been various proposed MARPE designs and the outcomes appear promising. The aim of the present article is to discuss the role of MARPE in clinical orthodontics by reviewing its background, design, indications, treatment effects, stability, and limitations in the current literature. The treatment effects of two types of MARPE, bone-borne and tooth-bone-borne (hybrid), will be individually assessed.