Analysis of midpalatal miniscrew-assisted maxillary molar distalization patterns with simultaneous use of fixed appliances: A preliminary study

The effects of palatal anchorage device on molar distalization with clear aligner: Three-dimensional finite element analysis

INTRODUCTION

This study aimed to analyze the biomechanical effects of the combined use of clear aligner and palatal anchorage devices (transpalatal arch [TPA], combination of TPA and microimplant [MI]) during maxillary molar distalization.

METHODS

Three-dimensional finite element models were established to simulate molar distalization, incorporating 7 configurations: Without-TPA, TPA-no-MI, TPA-with-MI1, TPA-with-MI2, TPA-with-MI3, TPA-with-MI4, and TPA-with-MI5. The 3-dimensional displacements of upper teeth and von Mises stress distribution in the periodontal ligament were evaluated.

RESULTS

The use of palatal anchorage devices enhanced the anchorage of anterior teeth and improved molar distalization. The efficacy of anchorage enhancement is related to the relative position of MI and the center of resistance of the maxillary dentition.

CONCLUSIONS

TPA placed on the first premolars effectively reinforces anterior anchorage during molar distalization with clear aligner. The combination of TPA and palatal MI can strengthen anterior tooth anchorage further.

Variations in the alveolar bone morphology in maxillary molar area: a retrospective CBCT study

BACKGROUND

This study quantitatively analyzed the anatomic structure of the alveolar bone in the maxillary molar region at three potential locations for Temporary Anchorage Device (TAD) placement. Additionally, the study compared the variability in this region across different age groups, sagittal skeletal patterns, vertical facial types, and sexes.

METHODS

In this retrospective cone-beam computed tomography study, the buccal alveolar bone was analyzed in the posterior molar area of 200 patients, the measurement items include buccal alveolar bone height, alveolar bone thickness, interradicular distance, and maxillary retromolar space.

RESULTS

Buccal alveolar height was greatest in the U56 region. The interradicular space was largest in the U56 region and increased from the alveolar crest to the sinus floor. Buccal alveolar bone thickness was highest in the U67 region and generally increased from the alveolar crest to the sinus floor. The maxillary retromolar space gradually increased from the alveolar crest to the root apex.

CONCLUSIONS

TADs are safest when placed in the buccal area between the maxillary second premolar and the first molar, particularly at the 9 mm plane. The U67 region is the optimal safe zone for TAD placement for maxillary dentition distalization. TADs placement in adolescents can be challenging. Maxillary third molar extraction can be considered for maxillary dentition distalization.

Palatal temporary skeletal anchorage devices (TSADs): What to know and how to do?

OBJECTIVES

Since palatal temporary skeletal anchorage devices (TSADs) have become important tools for orthodontic treatment, this narrative review was aimed to provide an updated and integrated guidelines for the clinical application of palatal TSADs.

SETTING AND SAMPLE POPULATION

A narrative review article including researches on palatal TSADs in orthodontics related to anatomy, success rate and clinical application.

MATERIALS AND METHODS

The anatomical characteristics, success rate and its consideration factors and clinical application of palatal TSADs based on the direction of tooth movement were evaluated.

RESULTS

To improve the stability of TSADs, hard tissue factors such as bone depth, cortical bone thickness, bone density and soft tissue thickness were evaluated. Anatomically risky structures, including the nasopalatine foramen, canal and the greater palatine foramen, nerve, vessel need to be identified before placement. The success rate of palatal TSADs was greater than that of the buccal inter-radicular space. Palatal TSADs have been used for various purposes because they can control tooth movement in all directions and, three-dimensionally; their applications include the retraction of anterior teeth, protraction of posterior teeth, distalization, intrusion, expansion and constriction. They can be applied directly or indirectly to the lingual arch or transpalatal arch. Design modifications using splinted 2 miniscrews have been suggested.

CONCLUSION

Palatal TSADs allow clinicians to perform minimally invasive and easy placement with good stability by understanding the anatomical characteristics of the palatal region, and they show good control over 3-dimensional tooth movements in various clinical cases.

Long-term stability of miniscrew anchored maxillary molar distalization in Class II treatment

OBJECTIVE

To investigate treatment stability of miniscrew-anchored maxillary distalization in Class II malocclusion.

MATERIALS AND METHODS

This retrospective study included a distalization (n = 19) and a control (n = 19) group; a patient group with minor corrections served the control. Lateral cephalograms of 38 adult patients were taken before (T0), immediately after (T1), and 3-4 years after (T2) treatment. Horizontal and vertical movement and tipping of the maxillary first molars (U6) and central incisors (U1) were measured along with skeletal craniofacial parameters at three time points to compare the two groups regarding the achieved treatment effects and their stability.

RESULTS

Total arch distalization therapy led to 4.2 mm of distal movement of U6 without distal crown tipping (0.6° of axis change) and 3.3° of occlusal plane steepening. Over an average retention period of 42 months, maxillary total arch distalization provided high stability of treatment results, showing the same amount of mesial movement (0.7 mm) as the control group.

CONCLUSIONS

In Class II treatment, miniscrew-anchored maxillary total arch distalization can provide stable distal movement of the maxillary first molars and central incisors.

Distalization with a modified C-palatal plate for severe upper crowding and a missing lower incisor

This case report presents the orthodontic treatment of a 25-year-old patient with skeletal Class II and severe maxillary arch crowding, moderate mandibular arch crowding, anterior crossbite, and a missing lower incisor. He was treated with molar distalization using a modified C-palatal plate and temporary anchorage devices to create sufficient space for retraction. The total treatment duration was 21 months. After treatment, his occlusion and smile esthetics showed significant improvement. The modified C-palatal plate represents a treatment modality that enhances the prospects of non-extraction treatment and reduces the need for extraction.

Comparación del grosor óseo palatino bilateral para inserción de miniimplantes

Objetivo: comparar el grosor óseo palatino bilateral e identificar zonas seguras para inserción de miniimplantes. Métodos: se llevó a cabo un estudio transversal que incluyó 100 tomografías de haz cónico (CBCT) pretratamiento de pacientes que asistieron a la Especialidad de Ortodoncia en la Universidad Autónoma de Nayarit (UAN). Las imágenes fueron orientadas utilizando el mismo protocolo. En el corte sagital, las mediciones se realizaron de los 0 a los 24mm, con intervalos de 3mm entre cada una, con la primera medición en el borde posterior del foramen incisivo. Las mediciones del grosor palatino se realizaron en el corte coronal a los 2, 4, 6 y 8mm de la sutura media palatina hacia ambos lados. Resultados: se encontró mayor grosor en la zona anterior en las medidas sagitales de 0 mm y 3 mm, a diferencia del resto del paladar. Se hallaron diferencias estadísticamente significativas al comparar los valores tanto sagitales como transversales. Con la prueba Post Hoc de Tukey no se encontraron diferencias estadísticamente significativas al comparar el lado derecho con el izquierdo en cada una de las medidas transversales. Conclusiones: no se encontraron diferencias significativas entre los dos lados, se determinó como zona segura la región anterior del paladar de 0mm a 6mm y es primordial la CBCT en todos los pacientes con indicación de miniimplantes en paladar.

Kate S, S. Potnis S, E. Kolge N. A simplified method for measurement of palatal bone thickness to select the optimum length of orthodontic mini-implant

Introduction

The palatal bone is a suitable site for mini-implant placement due to it being a “rootless area” with dense bone. This application has increased with mini-implant-assisted rapid palatal expansion becoming the preferred method of expansion. It is necessary to measure the vertical bone height with a reasonable accuracy, at the implant insertion site, to utilize the maximum available bone support, and to avoid the risk of perforations. As an accepted method, full-volume cone-beam computed tomography (CBCT) scan is advised for the same. This requires an additional procedure, further, radiation exposure, and cost to the patient. The aim of the study was to establish the utility of lateral cephalogram as a simple and reliable method to measure palatal bone thickness for placement of mini-implants in the 1st premolar and 1st molar region, which are the most common sites of mini-implant placement.

Materials and Methods

A total of 30 CBCT scans and digital lateral cephalograms of patients were selected and analyzed at the 1st premolar and molar region and were statistically evaluated using Student’s t-test and Wilcoxon rank-sum test.

Results

The results obtained indicated a highly significant correlation between the measurements obtained on lateral cephalograms at both the 1st premolar and 1st molar areas, P < 0.001.

Conclusion

The data presented show that lateral cephalometry provides a reliable assessment of the quantity of vertical bone for paramedian insertion of a palatal implant.

Comparison of treatment effects between four premolar extraction and total arch distalization using the modified C-palatal plate

Objective

The purpose of this study was to compare the skeletal, dental, and soft-tissue treatment effects of nonextraction therapy using the modified C-palatal plate (MCPP) to those of premolar extraction (PE) treatment in adult patients with Class II malocclusion.

Methods

Pretreatment and posttreatment lateral cephalographs of 40 adult patients with Class II malocclusion were retrospectively analyzed. The MCPP group comprised 20 patients treated with total arch distalization of the maxillary arch while the PE group comprised 20 patients treated with four PE. Fifty-eight linear and angular measurements were analyzed to assess the changes before and after treatment. Descriptive statistics, paired t-test, and multivariate analysis of variance were performed to evaluate the treatment effects within and between the two groups.

Results

The MCPP group presented 3.4 mm of retraction, 1.0 mm of extrusion, and 7.3° lingual inclination of the maxillary central incisor. In comparison, the PE group displayed greater amount of maxillary central incisor retraction and retroclination, mandibular incisor retraction, and upper lip retraction (5.3 mm, 14.8°, 5.1 mm, and 2.0 mm, respectively; p < 0.001 for all). In addition, the MCPP group showed 4.0 mm of distalization and 1.3 mm of intrusion with 2.9° distal tipping of the maxillary first molars.

Conclusions

These findings suggest the MCPP is an effective distalization appliance in the maxillary arch. The amount of incisor retraction, however, was significantly higher in the PE group. Therefore, four PE may be recommended when greater improvement of incisor position and soft-tissue profile is required.

Quantitative evaluation of palatal bone thickness for the placement of orthodontic miniscrews in adults with different facial types

Objectives:

To quantitatively evaluate palatal bone thickness in adults with different facial types using cone beam computed tomography (CBCT).

Methods:

The CBCT volumetric data of 123 adults (mean age, 26.8 years) collected between August 2014 and August 2016 was retrospectively studied. The subjects were divided into a low-angle group (39 subjects), a normal-angle group (48 subjects) and a high-angle group (36 subjects) based on facial types assigned by cephalometric radiography. The thickness of the palatal bone was assessed at designated points. A repeated-measure analysis of variance (rm-ANOVA) test was used to test the relationship between facial types and palatal bone thickness.

Results:

Compared to the low-angle group, the high-angle group had significantly thinner palatal bones (p<0.05), except for the anterior-midline, anterior-medial and middle-midline areas.

Conclusion:

The safest zone for the placement of microimplants is the anterior part of the paramedian palate. Clinicians should pay special attention to the probability of thinner bone plates and the risk of perforation in high-angle patients.

Evaluation of Palatal Bone Thickness for Insertion of Orthodontic Mini-Implants in Adults and Adolescents

OBJECTIVE

The aim of this study was to measure palatal bone thickness and select relatively safe regions for mini-implant insertion, and to determine the effect of age and sex on palatal bone thickness and whether there is any difference between right and left sides.

MATERIALS AND METHODS

Cone beam computed tomographic (CBCT) evaluation was used on 107 healthy orthodontic patients, including 51 adolescents (12.90 ± 1.71 years) and 56 adults (26.09 ± 4.35 years), who were selected from the Zhongshan Hospital, Fudan University (Shanghai, China). Seventy-two sites of bone thickness were measured in the palate. Intragroup, intergroup, and sex differences were analyzed by repeated measures analysis of variance.

RESULTS

Palatal bone thickness exhibited significant differences in 3 anteroposterior areas of the 2 groups. From anterior to posterior region, palatal bone thickness gradually decreased. Meanwhile, on the sagittal plane, palatal bone thickness decreased gradually from reference line 0 to 9 mm among adults, and from reference line 0 to 12 mm among adolescents posterior to the level of the posterior rim of the incisive foramen. However, on the coronal plane, no significant differences were found in the palatal bone thickness among reference lines 2, 4, 6, and 8 mm lateral to the midpalatal suture. Nor were there differences between right and left sides, between adults and adolescents or between males and females.

CONCLUSIONS

In terms of bone thickness, the anterior region is relatively safe for orthodontic mini-implant insertion. However, since subjects vary greatly, CBCT scans are needed before undertaking mini-implant insertion.

A comparison of treatment effects of total arch distalization using modified C-palatal plate vs buccal miniscrews

OBJECTIVE

The purpose of this study was to compare the treatment effects of palatally vs buccally placed temporary anchorage devices.

MATERIALS AND METHODS

Of 40 Class II division 1 malocclusion patients, 22 were treated with modified C-palatal plate (MCPP) appliances (age 21.9 ± 6.6 years), and 18 (age 24.2 ± 6.8 years) were treated with buccally placed miniscrews between the maxillary first molar and second premolar. A total of 26 linear and angular measurements were analyzed on pre- and posttreatment lateral cephalograms. Multivariate analysis of variance was performed to evaluate the treatment effects within each group and to compare the effects between groups.

RESULTS

Overall, the MCPP appliances showed 4.2 mm of distalization, 1.6 mm of intrusion of the first molar with 2° tipping, and 0.8 mm extrusion of incisors. The miniscrew group resulted in 2.0 mm of distalization, 0.1 mm intrusion of the first molar with 7.2° tipping, and 0.3 mm of incisor extrusion. Regarding soft tissue change, in the MCPP group, the upper lip was significantly retracted ( P < .001).

CONCLUSIONS

Comparing the treatment effects between MCPP appliances and buccal miniscrews, the MCPP appliances showed greater distalization and intrusion with less distal tipping of the first molar and less extrusion of the incisor compared to the buccal miniscrews.

Three-dimensional evaluation of tooth movement in Class II malocclusions treated without extraction by orthodontic mini-implant anchorage

OBJECTIVE

The aim of this study was to analyze tooth movement and arch width changes in maxillary dentition following nonextraction treatment with orthodontic mini-implant (OMI) anchorage in Class II division 1 malocclusions.

METHODS

Seventeen adult patients diagnosed with Angle's Class II division 1 malocclusion were treated by nonextraction with OMIs as anchorage for distalization of whole maxillary dentition. Three-dimensional virtual maxillary models were superimposed with the best-fit method at the pretreatment and post-treatment stages. Linear, angular, and arch width variables were measured using Rapidform 2006 software, and analyzed by the paired t-test.

RESULTS

All maxillary teeth showed statistically significant movement posteriorly (p < 0.05). There were no significant changes in the vertical position of the maxillary teeth, except that the second molars were extruded (0.86 mm, p < 0.01). The maxillary first and second molars were rotated distal-in (4.5°, p < 0.001; 3.0°, p < 0.05, respectively). The intersecond molar width increased slightly (0.1 mm, p > 0.05) and the intercanine, interfirst premolar, intersecond premolar, and interfirst molar widths increased significantly (2.2 mm, p < 0.01; 2.2 mm, p < 0.05; 1.9 mm, p < 0.01; 2.0 mm, p < 0.01; respectively).

CONCLUSIONS

Nonextraction treatment with OMI anchorage for Class II division 1 malocclusions could retract the whole maxillary dentition to achieve a Class I canine and molar relationship without a change in the vertical position of the teeth; however, the second molars were significantly extruded. Simultaneously, the maxillary arch was shown to be expanded with distal-in rotation of the molars.