Measurement of the midpalatal suture width

Comparison of the Effects of Different Palatal Morphology on Maxillary Expansion via RME and MSE: A Finite Element Analysis

OBJECTIVES

This study aims to compare and analyze the biomechanical effect and the displacement trend of RME and MSE on the maxillofacial complex under different palatal shapes by using finite element analysis.

METHODS

The three-dimensional model of maxillofacial complex was obtained from a computed tomography image of a person with a normal palate. Then, we modified the shape of the palate to obtain the model with a high palate. Additionally, two expander devices were considered. MSE and RME were created and four models were made: Model 1: Normal-palate craniomaxillofacial complex with RME expander; Model 2: Normal-palate craniomaxillofacial complex with MSE expander; Model 3: High-palate craniomaxillofacial complex with RME expander; Model 4: High-palate craniomaxillofacial complex with MSE expander. Then, lateral forced displacement was applied and the analysis results were obtained.

RESULTS

The lateral displacement of the palatal suture of Model 3 is greater than that of Model 1, and the maxilla has more rotation. The crown/root ratio of Model 1 is significantly greater than that of the other three groups. Compared with Model 1, Model 3 has greater stress concentration in the superstructure of the craniomaxillofacial complex. Both of them have greater stress in the anchorage area than Model 2 and Model 4.

CONCLUSION

Different shapes of the palate interfere with the effects of RME and MSE, and its influence on the stress distribution and displacement of the craniomaxillary complex when using RME is greater than MSE. The lateral displacement of the palatal suture of MSE is significantly larger than that of RME. It is more prone to tipping movement of the anchor teeth using RME under normal palate, and MSE may manage the vertical control better due to the smaller crown/root ratio than RME and intrusive movement of molars.

Effect of Different Mini Implant Assisted Rapid Palatal Expansion (MARPE) Designs on Maxillary Protraction in Skeletal Class III malocclusion: An FEM Study

Background

Four different designs of mini-implant-assisted rapid palatal expansion (MARPE) and protraction in nasomaxillary complex and mid-palatal sutures in late adolescent skeletal Class III malocclusion were compared using a three-dimensional finite element analysis.

Methods

A finite element model of skull and related sutures was constructed using the computed tomography scan of a 16-year-old female patient with skeletal Class III and ANB of -2°. Four appliance designs: Type I: MARPE with palatal force, Type II: MARPE with buccal force, Type III: Hybrid hyrax with palatal force, and Type IV: Hybrid hyrax with buccal force. Protraction vectors were and analyzed using Ansys software (ANSYS 2021 R2). The displacement pattern of the nasomaxillary structures and the stress distribution in the sutures were examined in all four appliance designs.

Results

All the appliance designs resulted in a forward movement of the maxilla, while Type I and III, which used palatal protraction force, caused the greatest forward displacement. In Type I, II, and III, along with forward movement, a clockwise rotation of maxilla was observed, while in Type IV, an anticlockwise rotation of maxilla was observed. Type I, II, and III resulted in higher stress distribution around the superior structures, while Type IV resulted in less stress distribution around the superior structures of maxilla.

Conclusion

The forward displacement was enhanced when palatal plates were used to protract the maxilla. The effective appliance design for skeletal class III with open bite case was Type I, II, and III and Type IV for deep bite cases.

Finite element analysis of sagittal screw expander appliance in the treatment of anterior maxillary hypoplasia

The skeletal anterior crossbite is a common malocclusion in clinic. However, there have been no reports on the maxillary sagittal expansion to correct the premaxillary hypoplasia, which greatly influences the facial morphology and masticatory function, using finite element analysis. In the present study, a three-dimensional finite element model of craniomaxillofacial complex with maxillary sagittal hypoplasia is constructed and the treatment for premaxillary hypoplasia by the sagittal screw expander appliance is simulated. The hypoplasia of the left premaxilla is more serious than that of the right and thus the size of the left part of premaxillary expander baseplate is designed to be larger than that of the right part and the loading is applied at 10° leftward to the sagittal plane and 30° forward and downward to the maxillary occlusal plane. The displacements or equivalent stress distributions of the maxilla, teeth and their periodontal ligaments, are analyzed under the loads of 5.0 N, 10.0 N, 15.0 N, and 20.0 N. Consequently, as the load increases, the displacements or equivalent stresses of the maxilla, teeth and their periodontal ligaments all increase. Almost the whole premaxilla markedly move forward, downward, and leftward while other areas in the craniomaxillofacial complex remain almost static or have little displacement. The equivalent stress concentration zone of the maxilla mainly occurs around and in front of the incisive foramina. The displacements of left premaxilla are generally greater than those of the right under the loading forces. The maximum equivalent stress on the teeth and their periodontal ligaments are 2.34E-02 MPa and 2.98E-03 MPa, respectively. Taken together, the sagittal screw expander appliance can effectively open the premaxillary suture to promote the growth of the premaxilla. An asymmetrical design of sagittal screw expander appliance achieves the asymmetric expansion of the premaxilla to correct the uneven hypoplasia and obtains the more symmetrical aesthetic presentation. This study might provide a solid basis and theoretical guidance for the clinical application of sagittal screw expander appliance in the efficient, accurate, and personalized treatment of premaxillary hypoplasia.

A novel method for assessment of human midpalatal sutures using CBCT-based geometric morphometrics and complexity scores

INTRODUCTION

Management of dentofacial deficiencies requires knowledge about sutural morphology and complexity. The present study assesses midpalatal sutural morphology based on human cone-beam computed tomography (CBCT) using geometric morphometrics (GMM) and complexity scores. The study is the first to apply a sutural complexity score to human CBCT datasets and demonstrates the potential such a score has to improve objectiveness and comparability when analysing the midpalatal suture.

MATERIALS AND METHODS

CBCTs of various age and sex groups were analysed retrospectively (n = 48). For the geometric morphometric analysis, landmark acquisition and generalised Procrustes superimposition were combined with principal component analysis to detect variability in sutural shape patterns. For complexity analysis, a windowed short-time Fourier transform with a power spectrum density (PSD) calculation was applied to resampled superimposed semi-landmarks.

RESULTS

According to the GMM, younger patients exhibited comparable sutural patterns. With increasing age, the shape variation increased among the samples. The principal components did not sufficiently capture complexity patterns, so an additional methodology was applied to assess characteristics such as sutural interdigitation. According to the complexity analysis, the average PSD complexity score was 1.465 (standard deviation = 0.010). Suture complexity increased with patient age (p < 0.0001), but was not influenced by sex (p = 0.588). The intra-class correlation coefficient exceeded 0.9, indicating intra-rater reliability.

CONCLUSION

Our study demonstrated that GMM applied to human CBCTs can reveal shape variations and allow the comparison of sutural morphologies across samples. We demonstrate that complexity scores can be applied to study human sutures captured in CBCTs and complement GMM for a comprehensive sutural analysis.

Stress distribution and displacement in the maxillofacial complex during intrusion and distalization of the maxillary arch using miniplates versus mini-implants: a 3-dimensional finite element study

OBJECTIVES

To three-dimensionally analyse the stress distribution and displacement pattern in the maxillofacial complex following intrusion and distalization of the maxillary arch using finite element analysis in skeletal class II malocclusion with prognathic maxilla and vertical maxillary excess using miniplates and mini-implants.

MATERIALS AND METHODS

Finite Element models of a skull, Y-shaped stainless steel miniplate, mini-implant and a posted arch were generated. Three force levels (1) 200 g (2) 300 g and (3) 500 g per side were applied to the assembly. The models were pre-processed and the analysis was performed using ANSYS version 18.1 software. Alterations in von mises stress, principal maximum stress, principal minimum stress and compressive stress were analysed around the sutures and surface landmarks.

RESULTS

With miniplates, there was a maximum stress concentration at the zygomatic buttress with even stress distribution at the fronto-maxillary, zygomatico-temporal, zygomatico-frontal and pterygomaxillary sutures along with anatomical landmarks such as frontal process of maxilla, ANS, Point A, prosthion and maxillary process of zygoma. First molars experienced greater distalization effects with buccal flaring when miniplates were used. With mini-implants, canine and premolars also exhibited greater distalization effects. In the root apices, lateral incisors showed increased lingual root movement with mini-implants.

CONCLUSION

Miniplates provide a greater distalizing effect while mini-implants produce increased intrusive effect. The distalizing effect is greater when 500 g of force is applied using miniplates with significantly even stress distribution and displacement pattern.

Midpalatal Suture CBCT Image Quantitive Characteristics Analysis Based on Machine Learning Algorithm Construction and Optimization

Background: Midpalatal suture maturation and ossification status is the basis for appraising maxillary transverse developmental status. Methods: We established a midpalatal suture cone-beam computed tomography (CBCT) normalized database of the growth population, including 1006 CBCT files from 690 participants younger than 24 years old. The midpalatal suture region of interest (ROI) labeling was completed by two experienced clinical experts. The CBCT image fusion algorithm and image texture feature analysis algorithm were constructed and optimized. The age range prediction convolutional neural network (CNN) was conducted and tested. Results: The midpalatal suture fusion images contain complete semantic information for appraising midpalatal suture maturation and ossification status during the fast growth and development period. Correlation and homogeneity are the two texture features with the strongest relevance to chronological age. The overall performance of the age range prediction CNN model is satisfactory, especially in the 4 to 10 years range and the 17 to 23 years range, while for the 13 to 14 years range, the model performance is compromised. Conclusions: The image fusion algorithm can help show the overall perspective of the midpalatal suture in one fused image effectively. Furthermore, clinical decisions for maxillary transverse deficiency should be appraised by midpalatal suture image features directly rather than by age, especially in the 13 to 14 years range.

Finite element and clinical analyses of effects of a new intraoral device (VomPress) combined with extraoral RAMPA on improving the overjet of craniofacial complex

This research intends to investigate the effects of a new intraoral device, VomPress, combined with a Right Angle Maxillary Protraction Appliance (RAMPA) extraoral device on the treatment of maxillary hypoplasia. To this end, finite element (FE) method has been employed and a skull model, including all sutures, has been investigated. In addition, the effects of VomPress combined with RAMPA on a seven-year-old girl with the malocclusion and other side problems were monitored. The results of both FE simulations and the clinical data revealed that VomPress combined with RAMPA effectively improved the malocclusion and straight neck problem by creating more space in the patient's mouth and anterosuperior protraction effects.

Effect of microimplant assisted rapid palatal expansion on bone-anchored maxillary protraction: A finite element analysis

INTRODUCTION

This study aimed to evaluate the craniofacial effects of microimplant assisted rapid palatal expansion (MARPE) on bone-anchored maxillary protraction (BAMP) through a finite element analysis.

METHODS

A 3-dimensional finite element model of the skull with associated sutures was created from the computed tomography image of a 12-year-old male patient. Two protraction protocols: BAMP without MARPE (protocol 1) and BAMP with MARPE (protocol 2), were analyzed using Ansys software (Ansys, Canonsburg, Pa). Stress distribution in the sutures and displacement pattern of craniofacial structures were analyzed in the 2 protocols using finite element analysis.

RESULTS

Both protocols produced changes in craniofacial structures in all the 3 planes. Displacement of the maxilla was more pronounced in protocol 2 in all directions with mild clockwise rotation. Protocol 1 displayed a translatory movement of the maxilla without any rotation and mild constriction in the anterior region. In protocol 2, an expansion of the maxilla, which increased in the superoinferior direction, was also observed. Von Mises stress in circummaxillary sutures was significantly more in protocol 2, indicating an increased displacement of craniomaxillary structures.

CONCLUSIONS

The use of MARPE during BAMP enhanced maxillary protraction and reduced the counterclockwise rotation tendency of the maxilla. Hence, it may be inferred that incorporation of MARPE during BAMP protocol may prove beneficial in the treatment of patients with skeletal Class III malocclusion with open bite tendency or hyperdivergent growth pattern.

Finite element simulations of the effects of an extraoral device, RAMPA, on anterosuperior protraction of the maxilla and comparison with gHu-1 intraoral device

OBJECTIVES

To investigate the effects of an extraoral device, right-angle maxillary protraction appliance (RAMPA), combined with a semi-rapid maxillary expansion intraoral device (gHu-1) on the anterosuperior protraction of maxillary bone.

MATERIALS AND METHODS

The finite element (FE) model included craniofacial bones and all sutures. The linear assumption was assumed for the FE simulations and the material properties of bones and sutures. The gHu-1 was simulated under screw activations equal to Δx = 0.25 and 0.5 mm in the lateral direction with and without RAMPA under a set of external forces {F1 = 2.94, F2 = 1.47, F3 = 4.44} N.

RESULTS

Displacement contours, nodal displacements of 12 landmarks, and von Mises stresses were compared. Combining RAMPA and gHu-1 (with Δx = 0.25 mm) resulted in changes in the displacement of the front part of the maxilla near the mid-palatal suture from (0.02, -0.1, -0.02) mm to (0.02, 0.3, 0.8) mm. For gHu-1 with Δx = 0.5 mm, the displacement of the same part changed from (0.04, -0.04, -0.2) mm to (0.04, 0.3, 0) mm. Similar trends were found in other locations.

CONCLUSIONS

The findings are in agreement with the previous cephalometric clinical data of an 8-year-old patient and prove the positive effects of RAMPA on the anterosuperior protraction of the maxilla when it is combined with the intraoral device gHu-1. In addition, RAMPA does not interfere with the lateral expansion generated by the intraoral device.

Mathematical modeling of palatal suture pattern formation: morphological differences between sagittal and palatal sutures

The median palatal suture serves as a growth center for the maxilla; inadequate growth at this site causes malocclusion and dental crowding. However, the pattern formation mechanism of palatal sutures is poorly understood compared with that of calvarial sutures such as the sagittal suture. In the present study, therefore, we compared the morphological characteristics of sagittal and palatal sutures in human bone specimens. We found that palatal suture width was narrower than sagittal suture width, and the interdigitation amplitude of the palatal suture was lower than that of the sagittal suture. These tendencies were also observed in the neonatal stage. However, such differences were not observed in other animals such as chimpanzees and mice. We also used a mathematical model to reproduce the differences between palatal and sagittal sutures. After an extensive parameter search, we found two conditions that could generate the difference in interdigitation amplitude and suture width: bone differentiation threshold [Formula: see text] and growth speed c. We discuss possible biological interpretations of the observed pattern difference and its cause.

Finite element analysis of stress caused by palatal orthodontic anchor screws

This study used finite element (FE) analysis to investigate the stability of miniscrews (screws) placed at the median palate. FE models with variable suture maturity and screw-suture distances were used to examine the relationship with screw stability. Four groups were classified by extent of maturation of the midpalatal suture (0%, 60%, 75%, and 100%). The placement position was set at the center of the suture (0.0 mm), or 0.5, 1.0, and 1.5 mm to the side of the suture, and von Mises stress values in bone and screw displacement were compared among models. The stress value for the unsutured model, in which the screw was placed at the center of the suture, was greater than 30 MPa. Stress values for models in which screws were placed to the side (0.5-1.5 mm) were less than 28 MPa. Maximum screw displacement was greater in the 0.0-mm incomplete suture model than at other placement positions. Because bone conditions vary among patients, placement position and suture maturation should be examined on cone beam-computed tomography images, to ensure screw stability.

Evaluation of Midpalatal Suture Ossification Using Cone-Beam Computed Tomography: A Digital Radiographic Study

BACKGROUND

Cone beam computed tomography (CBCT) imaging techniques are the recent rage in the field of oral diagnostic imaging modality. It is noninvasive, faster and lacks anatomic superimposition. Earlier maxillary occlusal radiographs were used to assess and evaluate the mid palatal suture, but being a two dimensional imaging modality it could not assess the ossification process which takes place in multiple planes mostly due to curved nature of the palate. In this study we assessed the mid palatal suture morphology and classify them according to the variants using CBCT images.

MATERIALS AND METHODS

A total of 200 CBCT scans (95 males and 105 females) were evaluated in the present study from the archives of an imaging center. As per Angelieri classification the midpalatal suture was classified into five categories (A-E) depending on the degree of ossification that had taken place. Statistical analysis was done by Chi Square test using SPSS version 23.0.

RESULTS

There is statistically significant difference present in the stages of maturity of mid palatal suture in various age groups with Stage B is most common in Group 1 (50%), Stage C most common in Group 2 (60%) and Group 3 (40%) and Stage E more common in Group 4 (50%).

CONCLUSION

The results of the present study showed a wide variation in the initiation time and the degree of ossification and morphology of the midpalatal suture in different age groups. Although there was an increase in the closure of the suture with aging, age is not a reliable criterion for determining the open or closed nature of the suture. This finding is important in providing an idea as to how diverse is the ossification of maxillary sutures.

Evaluation of the degree of fusion of midpalatal suture at various stages of cervical vertebrae maturation

Introduction:

Rapid palatal expansion was initially done during circumpubertal age. However, the correct evidence suggests visualizing the patency of midpalatal suture (MPS) radiologically at different chronological age as there can be early or late fusion of suture in some cases.

Objective:

This study was aimed at assessing the fusion of MPS at different stages of cervical vertebrae maturation and to find any correlation between them from the patients of two South Indian districts.

Design and Setting:

A total of 144 subjects aged 10–20 years were included in our study.

Materials and Methods:

Skeletal age based on cervical vertebrae was assessed from lateral cephalograms. MPS staging was done by two observers using cone-beam computed tomography at 2-time intervals. Inter- and intra- examiner reliability for suture staging was analyzed by kappa statistics. Correlation of skeletal age to sutural maturation was done using Kendall’s tau-b test.

Results:

A fair agreement was obtained by kappa test for inter (0.313) and intraexaminer reliability (0.219 for first and 0.451 for the second observer) for 144 subjects. Kendall’s tau-b test showed a significant correlation between skeletal age and suture maturation, with the maximum association between CS 4 skeletal age and Stage C of MPS, with P < 0.001.

Conclusion:

A strong correlation was found between skeletal age and sutural fusion. Predominantly, Stage C coincided with CS 4 with greater gender predilection toward females.

Anterosuperior protraction of maxillae using the extraoral device, RAMPA; finite element method

This paper presents a boosting effect against gravity by analyzing the displacement and stress distribution of craniofacial structures due to the protraction of the extraoral device, the Right Angle Maxillary Protraction Appliance(RAMPA) system, including semi-rapid maxillary expansion (sRME) using the finite element method. In addition, a patient case was illustrated and compared with the results calculated from a simulation. The results from the finite element method were obtained for 0.5 mm activation using the screw of the intraoral device, gHu-1. This study reveals that RAMPA rotates the patient's maxilla and mandible in the forward direction and forces them to move forward and upward.

Displacement and stress distribution of the maxillofacial complex during maxillary protraction using palatal plates: A three-dimensional finite element analysis

Objective

The purpose of this study was to analyze initial displacement and stress distribution of the maxillofacial complex during dentoskeletal maxillary protraction with various appliance designs placed on the palatal region by using three-dimensional finite element analysis.

Methods

Six models of maxillary protraction were developed: conventional facemask (Type A), facemask with dentoskeletal hybrid anchorage (Type B), facemask with a palatal plate (Type C), intraoral traction using a Class III palatal plate (Type D), facemask with a palatal plate combined with rapid maxillary expansion (RME; Type E), and Class III palatal plate intraoral traction with RME (Type F). In Types A, B, C, and D, maxillary protraction alone was performed, whereas in Types E and F, transverse expansion was performed simultaneously with maxillary protraction.

Results

Type C displayed the greatest amount of anterior dentoskeletal displacement in the sagittal plane. Types A and B resulted in similar amounts of anterior displacement of all the maxillofacial landmarks. Type D showed little movement, but Type E with expansion and the palatal plate displayed a larger range of movement of the maxillofacial landmarks in all directions.

Conclusions

The palatal plate served as an effective skeletal anchor for use with the facemask in maxillary protraction. In contrast, the intraoral use of Class III palatal plates showed minimal skeletal and dental effects in maxillary protraction. In addition, palatal expansion with the protraction force showed minimal effect on the forward movement of the maxillary complex.

Displacement and stress distribution by different bone-borne palatal expanders with facemask: A 3-dimensional finite element analysis

INTRODUCTION

The purpose of this study was to analyze displacement and stress distribution in the maxilla during maxillary expansion followed by protraction using bone-borne and conventional tooth-borne palatal expanders and a facemask via 3-dimensional finite element analysis.

METHODS

A finite element model of an adolescent skull was created, and 4 different types of appliances were integrated into it: facemask (type A); facemask with paramedian bone-borne expander (type B), facemask with palatal-slope bone-borne expander (type C), and facemask with conventional expander (type D). Expansion of 0.25 mm followed by 500 g of force per side was applied.

RESULTS

Type A showed anterior displacement of the dentition combined with downward displacement of posterior teeth and upward displacement of anterior teeth. The combination of protraction and expansion in type D showed the greatest anterior displacement. In types B and C, the expansion forces resulted in posterior displacement decreasing the net displacement of the combination. Stresses concentrated around the miniscrews in types B and C. In types A and D, stresses concentrated at the first premolar and first molar. Type B had the highest stresses followed by type C and then D.

CONCLUSIONS

The conventional tooth-borne expander (type D) enhanced the effect of maxillary protraction. Facemask alone (type A) resulted in more anterior displacement of the maxilla than the combination of facemask and bone-borne expanders (types B and C). The clinician should be aware of the initial stresses and movements from different expanders with facemask found in this study and confirm the movements in future clinical Class III studies.

Assessment of midpalatal suture ossification using cone-beam computed tomography

BACKGROUND AND OBJECTIVE

The degree of ossification of the midpalatal suture is an important factor in the selection of treatment procedure, especially in young individuals. Considering the discrepancies in the results of studies on the exact time of the closure of this suture, the present study was undertaken to evaluate ossification and morphology of the suture with the use of CBCT.

METHODS

In the present cross-sectional study, the CBCT images of the maxilla in 144 Iranian subjects (72 males, 72 females) with an age range of 10 to 70 years, referring to a private radiology center in Sari, Iran, were evaluated. The CBCT images were evaluated in the axial cross-sectional slice at 1 mm intervals to determine morphology and the maturation stage of the suture and its degree of ossification. The six developmental stages that were observed were as follows: stage A, a direct line without disturbances; stage B, a scalloped appearance in the suture; stage C, two parallel lines with a scalloped appearance that were connected at some points; stage CD, the anterior portion was similar to stage C, and the posterior region was similar to stage D; stage D, ossification only in the palatine bone; stage E, complete ossification of the suture. The degree of ossification of the suture was calculated with the use of the ratio of the length of the ossified segment to the entire length of the suture. Data were analyzed with Spearman's correlation test, Chi-squared test, t-test, ANOVA, Mann-Whitney U, and Kruskal-Wallis test. Intra-observer agreement was calculated with the use of weighted kappa coefficient. Data were analyzed with SPSS 17.

RESULTS

There was a strong correlation between the age groups and the developmental stages of the midpalatal suture in both genders (r=0.681, p<0.001). The ossification process occurred in the posterior to anterior direction in 98% of the cases. There was a significant relationship between aging and the degree of ossification (p<0.001); however, the difference was not significant between the two genders (p=0.193).

CONCLUSION

Although the rate of suture closure increased with aging, age was not a reliable factor alone to determine the developmental stage of the suture. Use of CBCT is necessary in all the patients to determine the degree of ossification and morphology of the midpalatal suture.

Rapid maxillary expansion in adults: Can multislice computed tomography help choose between orthopedic or surgical treatment?

INTRODUCTION

The aim of this study was to evaluate the accuracy of Multislice Computed Tomography (MSCT) in the detection resistance areas on the midpalatal suture (MPS) and thus to evaluate if MSCT could be a help in the kind of maxillary expansion to be used (pure orthodontic or surgically-aided) for the correction of transverse maxillary deficiencies in adults.

METHODS

Ten MSCT were obtained from 10 MPS removed from fresh corpses (mean age: 79.4; extreme: 70-86). Three standardized radiological regions of interest (ROI) were identified on each MPS and were classified into "open" (group 1) or "closed" (group 2) by 3 independent radiologists. The 30 ROI were then histologically analyzed according to 3 criteria: mean suture width (MSW), obliteration index (OI) and interdigitation index (Ii).

RESULTS

Nine ROI were classified in group 1 (closed) and 21 in group 2 (open). On the histological examination, the mean MSW was 396.9μm in group 1 and 227.1μm in group 2. OI was 3.098% and 9.309% and Ii was 1.25 and 1.34 respectively. Statistically significant difference between the 2 groups was only found for the MSW. We conclude that MSCT allows for the evaluation of the width of the MPS, but not for the evaluation of the other possible parameters of resistance we used. Therefore, it cannot predict precisely the amount of résistance in the MPS and is not suited for the choice between pure orthodontic or surgically-aided expansion.

A comparison of three-dimensional stress distribution and displacement of naso-maxillary complex on application of forces using quad-helix and nickel titanium palatal expander 2 (NPE2): a FEM study

Background

Our objectives are to analyse and to compare the stress distribution and displacement of the craniofacial structures, following the application of forces from quad-helix and Nickel Titanium Palatal Expander-2 (NPE2) using finite element analysis.

Methods

Three-dimensional finite element models of young dried human skull, quad-helix appliance and NPE2 were constructed, and the initial activation of the expanders was stimulated to carry out the analysis and to evaluate the Von Misses stresses and displacement.

Results

Both the models demonstrated the highest stresses at the mid-palatal suture, with maximum posterior dislocation. The second highest stress was recorded at the fronto-zygomatic suture. The pattern of stress distribution was almost similar in both the groups, but NPE2 revealed lower magnitude stresses than quad-helix. The only exception being quad-helix model showed high stress levels around pterygo-maxillary suture whereas minimal stress around pterygo-maxillary suture was noticed after NPE2 activation. The cusp of the erupting canine and the erupting mesiobuccal cusp of the second molar showed outward, backward and downward displacement signifying increase in their eruption pattern following maxillary expansion.

Conclusions

Maxillary expansion using quad-helix and NPE2 can be used in posterior crossbite correction in cases where maximum skeletal changes are desirable at a younger age; it is furthermore effective in treating young patients with impacted or displaced teeth. Quad-helix and NPE2 produced acceptable forces for orthopaedic treatment even after being orthodontic appliances; their clinical application should be correctly planned as the effects of these appliances are largely age dependent.

A unique functional craniofacial suture that may normally never ossify: A cone-beam computed tomography-based report of two cases

The premise of complete ossification of midpalatal suture in early adulthood still has its popularity, though conflicting data are emerging in the literature. A 49-year-old male and a 54-year-old female Iranian patient, both dentulous, were referred to a Maxillofacial Radiology Center to be evaluated for implant insertion. In cone-beam computed tomography (CBCT) evaluation, an in-ossified suture was found in anterior two-third of midpalatal region of both individuals. The application of clinical vignettes from CBCT findings for maxillofacial orthodontic and orthopedic purposes is of value. Existing cases of successful nonsurgical rapid palatal expansion of maxilla in adults could surrogate this dogma about timing for ossification of midpalatal suture which is considered as a purely chronologic-related phenomenon and transmitted masticatory forces may be one possible cause (functional hypothesis).

Displacement and stress distribution of the maxillofacial complex during maxillary protraction with buccal versus palatal plates: finite element analysis

OBJECTIVES

The aim of this study was to analyse the displacement and stress distribution in the maxillofacial complex during maxillary protraction with buccal and palatal plates using three-dimensional finite element analysis.

MATERIALS AND METHODS

Three anchorage appliance models-palatal plate (Type A), miniplate at the infrazygomatic crest (Type B), and conventional tooth-borne appliance (Type C)-were designed and integrated into a skull model. Protraction force was 500 g per side and force direction was forward and 30 degree downward to the maxillary occlusal plane. The stress distribution around the circum-maxillary sutures and the displacement of the surface landmarks were analysed.

RESULTS

All models showed forward and upward displacement at anterior nasal spine, Point A, and prosthion and forward and downward displacement at posterior nasal spine resulting in a counter-clockwise rotation. This anterior displacement was greatest in Type A. At the maxillary process of the zygoma, upward movement was shown only in Type A, whereas downward movement was observed in Types B and C. The greatest stresses in Type A were at the pterygomaxillary and the zygomaticotemporal sutures. Type B showed the greatest stress at the frontomaxillary suture.

LIMITATIONS

Type A showed asymmetric results; however, it was not of clinical significance.

CONCLUSION

The palatal plate resulted in wider stress distribution and more forward displacement compared to miniplate at the infrazygomatic crest area and conventional tooth-borne appliances. It might be recommended to consider the application of the palatal plate for maxillary protraction in Class III patients.

Effect of bone-borne rapid maxillary expanders with and without surgical assistance on the craniofacial structures using finite element analysis

INTRODUCTION

The aim of this study was to analyze stress distribution and displacement of the craniofacial structures resulting from bone-borne rapid maxillary expanders with and without surgical assistance using finite element analysis.

METHODS

Five designs of rapid maxillary expanders were made: a tooth-borne hyrax expander (type A); a bone-borne expander (type B); and 3 bone-borne surgically assisted modalities: separation of the midpalatal suture (type C), added separation of the pterygomaxillary sutures (type D), and added LeFort I corticotomy (type E). The geometric nonlinear theory was applied to evaluate the Von Mises stress distribution and displacement.

RESULTS

The surgical types C, D, and E demonstrated more transverse movement than did the nonsurgical types A and B. The amounts of expansion were greater in the posterior teeth in types A and B, but in types C, D, and E, the amounts of expansion were greater in the anterior teeth. At the midpalatal suture, the nonsurgical types showed more anterior expansion than did the posterior region, and higher stresses than with the surgical types. Type B showed the highest stresses at the infraorbital margin, anterior and posterior nasal spines, maxillary tuberosity, and pterygoid plate and hamulus.

CONCLUSIONS

The 3 surgical models showed similar amounts of stress and displacement along the teeth, midpalatal sutures, and craniofacial sutures. Therefore, when using a bone-borne rapid maxillary expander in an adult, it is recommended to assist it with midpalatal suture separation, which requires minimal surgical intervention.