Failure load and stress analysis of orthodontic miniscrews with different transmucosal collar diameter

Evaluation of Palatal Thickness for the Placement of MARPE Device among a Cohort of Iraqi-Kurdish Population: A Retrospective CBCT Study

Objectives

This study aimed to evaluate and compare palatal thickness in adults for the placement of mini-implants for miniscrew-assisted rapid palatal expansion (MARPE) appliances using cone-beam computed tomography (CBCT) in a sample of Iraqi-Kurdish people.

Materials and Methods

CBCT scans from 68 Kurdish patients, aged between 18 and 30 years, were assessed retrospectively. Of these, 37 were males and 31 were females. The measurements were performed at 3 mm from the mid-palatal suture. T-zone was selected for the anterior points, at the level of the palatal cusps of 2nd premolars, and the posterior point at the level of mesio-palatal cusps of 1st molars bilaterally. Palatal thickness of males and females bilaterally, as well as anterior and posterior areas, were measured and compared. An independent t-test was applied for comparison for normally distributed data, and the Mann-Whitney test was utilized for nonnormally distributed data. Additionally, Bonferroni correction was implemented for p-value adjustment.

Results

The mean palatal thickness at the anterior area was 6.06 mm for males, 6.17 mm for females on the right side, 5.94 mm for males, and 5.99 mm for females on the left side. The mean palatal thickness at the posterior area was almost the same for both genders (4.40 mm for males and 4.44 mm for females) on the right side, 4.35 mm for males, and 4.54 mm for females on the left side. Statistically, no significant difference was recorded between males and females, as well as right and left sides in both anterior and posterior regions; however, a very highly statistically significant difference (p  < 0.001) was recorded when comparing total thickness, including both hard and soft tissue, between anterior and posterior regions.

Conclusions

CBCT proves a highly effective modality in assessing palatal thickness and suggesting ideal locations for orthodontic mini-screw placement. Our examination of palatal thickness in a sample of Iraqi-Kurdish individuals revealed no statistical difference between genders or sides, but significant variations were noted between anterior and posterior thicknesses. Comprehensive clinical and pre-expansion CBCT evaluations are crucial for precisely determining the optimal placement of MARPE devices in each patient, ensuring successful outcomes.

Effect of cortical bone thickness on shear stress and force in orthodontic miniscrew-bone interface - A finite element analysis

Miniscrews are widely used in orthodontics as an anchorage device while aligning teeth. Shear stress in the miniscrew-bone interface is an important factor when the miniscrew makes contact with the bone. The objective of this study was to analyze the shear stress and force in the screw-bone interface for varying Cortical Bone Thickness (CBT) using Finite Element Analysis (FEA). Varying CBT of 1.09 mm (1.09CBT) and 2.66 mm (2.66CBT) with miniscrews of Ø1.2 mm, 10 mm length (T1), Ø1.2 mm, 6 mm length (T2) and Ø1.6 mm, 8 mm length (T3) were analyzed. Six Finite Element (FE) models were developed with cortical, cancellous bone, miniscrews and gingiva as a prism. A deflection of 0.1 mm was applied on the neck of the miniscrews at 0°, +30° and -30° angles. The shear stress and force in the screw-bone interface were assessed. The results showed that the CBT affects the shear stress and force in the screw-bone interface region in addition to the screw dimensions and deflection angulations. T1 screw generated lesser shear stress in 1.09CBTand 2.66CBTcompared to T2 and T3 screws. Higher CBT is preferred for better primary stability in shear aspect. Clinically applied forces of 200 gms to 300 gms to an anchorage device induces shear stress in the miniscrew-bone interface region might cause stress shielding. Thus, clinicians need to consider the effect of varying CBT and the size of the miniscrews for the stability, reduced stress shielding and better anchorage during orthodontic treatment.

Clear Aligners and Miniscrews in a Scissor Bite Adult Treatment

Scissor bite does not correct spontaneously. It gradually worsens by overeruption, negatively affecting masticatory function. It is intended with this manuscript to evaluate the different treatment strategies to correct this malocclusion in adult patients, exploring treatment with clear aligners, bite ramps, and MS (miniscrews), especially in this case of a patient with unilateral right scissor bite, with high dental compensation in the three planes of space, asymmetrical sagittal dental position, overeruption on the scissor bite condition, and a high mandibular arch constriction and maxillary expansion. A comprehensive literature research was performed from 2002 until March 2023. PubMed and BVS databases were used, with the following keywords: "scissor bite OR brodie bite" AND "malocclusion" AND "treatment OR correction OR therapeutics". Since correcting skeletal asymmetries after the growth completion is challenging, adult patient cases often involve a combined orthodontic-surgical approach. In the present clinical case, the severe limitations to decompensating tooth positions for a surgical treatment, with the necessity to perform lower asymmetric extraction and a must longer orthodontic treatment, were the major reasons to avoid the surgical approach, after the scissor bite correction. In spite of this, the efficiency of the clear aligners and auxiliaries like bite ramps, MS, and elastics in successfully correcting a complex scissor bite in an adult patient was demonstrated, with significant esthetic and functional commitment, demonstrated by the case reliability PAR (peer assessment rating) index.

Oral Implantology: Current Aspects and Future Perspectives

In recent years, dental implantology has significantly improved with the development of more advanced techniques which have greatly increased the reliability of dental implant therapy while reducing patient morbidity [...]

Characteristics and Risk Factors for the Fracture of One-Piece Implants

Objective

The one-piece dental implant was originally designed to overcome the structural weaknesses of the two-piece implant. However, a fractured one-piece implant requires removal because the abutment cannot be repaired or replaced to support new prosthetic restorations. The aim of this study was to clarify the features and risk factors for fracture of the one-piece implant.

Methods

This study was designed as a retrospective case series research. The subjects were patients who were treated for fractures of the one-piece implant at a clinic in Japan between 2012 and 2021. Fractures of the one-piece implant were diagnosed by cone-beam computed tomography, and the association between age and duration from implant placement to fracture was analyzed by one-way ANOVA followed by the Tukey test.

Results

Eighteen patients and 20 one-piece implants (under 39 years: 5 patients and 6 implants; 40-59 years: 7 patients and 7 implants; over 60 years: 6 patients and 7 implants) had fractures in their one-piece implants. Of the fractured implants, 11 had a diameter of 3 mm, and 9 had a diameter of 4 mm. The mean durations up to implant fracture were 662 days in the younger group, 1467 days in the middle group, and 1239 days in older group, and the duration was significantly shorter in the younger group. In addition, 83.3% of fracture implants in the younger group were in the molar region. All fractures of the one-piece implants occurred under the bone margin. Two patients had torus mandibularis, and 1 patient was had bruxism.

Conclusions

One-piece implants in younger patients that are located in the lower molar position are the most susceptible to implant fracture, and the fracture occurred under the bone margin in all cases.

The effect of different orthodontic mini-implant brands and geometry on primary stability (an in vitro study)

Background

In orthodontic procedures, mini-implants are routinely used as temporary anchorage devices. Early failure is primarily attributed to a variety of issues, which are mostly connected to the quality and geometry of the screw that lead to insufficient primary stability.

Objectives

To evaluate the primary stability of different sizes and brands of orthodontic mini-implants by optimizing the insertion torque value (ITV) and to clear out which one has the greatest primary stability among the most widely used mini-implants by orthodontists.

Methods

Eighty-two self-drilling mini-implants from three different brands with different sizes were used (Optimus Ortho System (Osteonic made in Korea), Smart anchor (GNI made in Korea) (1.4 × 6, 1.6 × 8 and 1.8 × 10mm) and Morelli (made in Brazil) (1.5 × 6, 1.5 × 8 and 1.5 × 10mm), made from (Ti 6Al 4V). All were drilled at a 60° angle on Sixty artificial bone blocks made from polyurethane foam with a digital torque meter device (Orthonia, Jeil made in Korea), pullout strength (tensile force) was measured with a universal testing machine to find out the best brand and size in the mean of primary stability. Data were analyzed using SPSS Version 25 and JMP Pro Version 16 software using the One-way ANOVA test, the Post hoc and Tukey HCD tests.

Results

There were significant differences between the pullout strength of different sizes for the GNI and OSTEONIC brands, while for the MORELLI brand there were no significant differences between the three different sizes considering ITV (10Ncm) whereas for ITV (20Ncm) there was a significant difference between the different sizes for the pullout of all three brands. GNI was the best brand for all the selected sizes with ITV (10Ncm) and size 1.4 × 6 for ITV (20Ncm), whereas OSTEONIC sizes 1.6 × 8 and 1.8 × 10 were the best for ITV (20Ncm) in term of primary stability.

Conclusion

GNI screws were demonstrated higher primary among the three widely used brands followed by OSTEONIC for size 1.6 × 8 and 1.8 × 10 while MORELLI was the least resistant to dislodgement for the two torque insertion values 10 N/cm and 20 N/cm.

Conservative Treatment of Bilateral Impacted Mandibular Canines Traction

The objectives of the treatment of impacted canines differ according to the characteristics of dental malocclusion. Traction of the tooth is a conservative and viable alternative, which allows for maintaining stability and occlusal function. The following case report describes the treatment of an 11.6-year-old female patient, who presented bilateral impaction of mandibular canines in contact with the midline, mixed dentition in the inter-transitional period, class I angle malocclusion, with light crowding teeth. The treatment comprised three phases. The first phase, verticalization of the mandibular canines in mixed dentition, was performed to pull the impacted bilateral mandibular canines towards the dental arch to achieve their verticalization, maintaining the molar relationship, and the position of the upper and lower incisors. In the second phase, osteogenic rest was planned to relieve post-traction stress while awaiting the replacement of the mixed dentition. Finally, the third phase in permanent dentition was to align and level canines within the arch after extraction of the deciduous canines. For the viability of the permanent mandibular canines in the dental arch, orthosurgical traction was implemented, with a traction system with closed nickel-titanium coil springs with a transitory rigid dental-mucous-supported anchorage device, which allowed control and protection of the adjacent teeth and movements with helical forces of a controlled three-dimensional range. The results of the treatment were adequate, achieving consolidated molar and canine relationships, overjet, overbite, and optimal facial balance.

Improved super-elastic Ti-Ni alloy wire for treating adult skeletal class III with facial asymmetry: A case report

BACKGROUND

Correcting severe skeletal class III malocclusion with facial asymmetry in adults through orthodontic treatment alone is difficult.

CASE SUMMARY

In this case report, we describe orthodontic treatment and lower incisor extraction without orthognathic surgery for a 27-year-old man with a transverse discrepancy. The extraction sites were closed using an elastic chain. The use of intermaxillary elastics, improved super-elastic Ti-Ni alloy wire, and unilateral multibend edgewise arch wire was crucial for correcting facial asymmetry and the midline deviation.

CONCLUSION

After treatment, the patient had a more symmetrical facial appearance, acceptable overjet and overbite, and midline coincidence. The treatment results remained stable 3 years after treatment. This case report demonstrates that a minimally invasive treatment can successfully correct severe skeletal class III malocclusion with facial asymmetry.

Osseointegration of Tantalum Trabecular Metal in Titanium Dental Implants: Histological and Micro-CT Study

This study aimed to investigate the impact of the Tantalum Trabecular Metal dental implant design on implant stability and the process of osseointegration following its placement in the rabbit femoral condyle. The subjects for the experiment consisted of 10 New Zealand white rabbits. Twenty implants, comprising 10 Trabecular Metal (TM) and 10 Traditional Screw Vent (TSV) implants, were placed into the femoral condyles of these rabbits. The implant type was alternated based on a random sequence. Following a healing period of 8 weeks, the implants were retrieved for further analysis using micro-computed tomography (micro-CT), histological studies, and histomorphometry evaluations. The Bone-to-Implant Contact (BIC) ratio and the Bone Volume (BV) percentage in the region of interest were subsequently assessed. The BIC and BV values between TM and TSV implants were compared using the Student t-test. The TM implants exhibited significantly greater BIC and BV scores. In particular, the BIC percentage was recorded as 57.9 ± 6.5 for the TM implants, as opposed to 47.6 ± 8 for the TSV implants. Correspondingly, the BV percentage was 57 ± 7.3 for the TM implants and 46.4 ± 7.4 for the TSV implants. The bone volume percentage measured using micro-CT evaluation was 89.1 ± 8.7 for the TM implants and 79.1 ± 8.6 for the TSV implants. Given the observed results, it is plausible to suggest that the bone growth surrounding the tantalum mesh could have improved the integration of the bone and facilitated its ingrowth into the TM implant.

Improved super-elastic Ti–Ni alloy wire intrusion arch for skeletal class II malocclusion combined with deep overbite: A case report

BACKGROUND

Treatment for deep overbite cases can be difficult. This case report presents some techniques with improved super-elastic Ti–Ni alloy wire (ISW) for deep overbite correction.

CASE SUMMARY

A 21-year-old woman had a chief complaint of flaring maxillary teeth. Orthodontic evaluation revealed a skeletal class II malocclusion and a convex profile appearance. A deep overbite with palatal impingement and large overjet were also noted. Bilateral maxillary first premolars were extracted, and spaces were closed using a closed-coil spring and elastic chain. The deep overbite was corrected by applying the ISW curve and ISW intrusion arch. Intermaxillary elastics was used to adjust the intermaxillary relationship. Active treatment took approximately 3 years, and the appearance and dentition alignment noticeably improved.

CONCLUSION

The use of the ISW technique in a case of skeletal class II malocclusion with deep overbite achieved a desirable result, and the patient was satisfied with the treatment outcome.

Camouflage Correction of Skeletal Class III Severe Open Bite with Tooth Ankylosis Treated by Temporary Anchorage Devices: A Case Report

Tooth ankylosis is a disorder characterized by the fusion of tooth and alveolar bone. This case report describes the treatment of a severe open bite due to tooth ankylosis. A 14-year-old female patient with a chief complaint of masticatory dysfunction was diagnosed with skeletal Class III severe anterior open bite and tooth ankylosis. She visited our university hospital with a chief complaint of an anterior open bite. After the surgical luxation of the ankylosed maxillary right central incisor, the tooth was orthodontically retracted using a nickel-titanium wire. The right mandibular lateral incisor and canine were luxated and retracted using intermaxillary elastics from a temporary anchorage device (TAD), which was inserted in the opposite jaw. During the treatment, skeletal Class III malocclusion deteriorated due to anterior growth of the mandible. Therefore, TADs were inserted into the retromolar pad on both sides of the mandible and retracted into the mandibular dental arch. Although the mandibular right canine was luxated several times, it could not be brought to the occlusal line, and was thus extracted; the extraction space was replaced with a prosthesis. Consequently, a normal overjet and overbite with a straight profile were achieved. Extrusion of ankylosed teeth by intermaxillary elastics from a TAD is a valid treatment option for patients with severe open bites.

New Materials and Techniques for Orthodontics

Orthodontics is a specialty of dentistry dealing with the prevention, diagnosis, and treatment of mispositioned jaws and teeth [...].

Clinical Applications for Dentistry and Oral Health

In the last few years, dentistry has expanded the scope of its research and increased its cooperation with other disciplines [...]

The Use of TADs in the Mandibular Arch to Prevent Proclination of the Lower Incisors during the Use of the Mini Scope Herbst Appliance

Class II malocclusions are the most frequent within the Italian population. Normally, these malocclusions are caused by a reduction in a mandibular component whose functional stimulus is still very much cause for debate. The negative effect of all types of Class II functional appliances is in the proclination of the lower incisors, which, in subjects whose incisors are already labially inclined, must be checked at all times to avoid serious consequences to these elements. In this case study, a girl aged 14 years and 5 months presented with Class II malocclusion, 2nd division with a convex profile and a visibly retruded chin. The lower incisors presented a marked proclination (-1/Go-Gn ini = 107.7°) in a brachyfacial patient. To avoid further inclination of the lower incisors a Herbst appliance was mounted in two separate sittings. The first part of the appliance including the tubes was mounted to the upper jaw allowing the vestibularisation of the upper incisors in order to increase the overjet. Once this was obtained the lower part of the appliance was mounted together with the telescopic arms associated with two temporary anchorage devices (TADs) in positions 36-37 and 46-47, and an anterior section 33-43 with distal loop to which two double metallic ligatures were anchored at the TADs to contrast the negative effect of the appliance. At the end of the first functional phase, the treatment was refined using MBK fixed therapy to finish the case. The orthodontic therapy led to a visible improvement of the profile and the achievement of a first-class dental-skeletal result on both sides. From the cephalometric evaluation carried out immediately after the Herbst appliance treatment at time T1 and at the end of the orthodontic therapy T2 it was possible to verify a slight increase in the inclination of the lower incisors (-1/Go-Gn fin = 108°). In conclusion, it can be said that the use of the skeletal anchorage avoided, in this case, the proclination effect in the lower incisors due to the use of a Herbst appliance.

Management of a Complex Dentoalveolar Traumatic Injury with Multiple Avulsions

Background

Dentoalveolar trauma is a major cause of tooth loss in children. Avulsion, luxation, crown, and root fracture are the injuries to primary and permanent dentition. The incidence of trauma for maxillary anterior teeth ranges for 4%-91%. Many case reports have been published regarding the treatment of trauma to anterior teeth; however, case reports comprising multiple avulsions including canines and premolars are rare in literature.

Method

After mouth rinsing was done with 2% betadine solution, the luxated teeth numbers 31 and 42 were repositioned into the tooth socket and were secured with the composite resin-wire splint. Tooth number 32 was extracted because it was disarticulated from the socket, and the socket was disrupted because of the alveolar fracture. The maxillary avulsed teeth could not be reimplanted because of the alveolar socket damage which was due to the alveolar bone fracture.

Results

The patient was reevaluated for the removable prosthesis in recall visits; the patient was well adapted to the appliance with no complaints regarding mastication and speech. The patient was advised to report periodically for further adjustments in the prosthesis and for radiographic evaluation.

Conclusions

This case report includes proper history taking, diagnosis, and treatment of a complex dentoalveolar trauma along with short-term prosthetic rehabilitation for improvement of aesthetics, phonetics, and mastication of growing child.

Management and Follow-Up of Complicated Crown Fractures with Intrusive Luxation of Maxillary Incisors in an 8-Year-Old Boy

Intrusive luxation is a severe form of dental injury which causes damage to the pulp and supporting structures of a tooth because of its dislocation into the alveolar process. This paper shows the case of the reeruption of maxillary incisors accompanied by complicated crown fractures after 3 months. An 8-year-old boy patient was referred to the Department of Pedodontic Dentistry of Tehran University of Medical Science, Tehran, Iran, 18 hours after a fall at school. Clinical and radiographic examinations revealed intrusive luxation of both incisors with complicated crown fractures. Cervical pulpotomy is the treatment of choice for traumatized immature intruded teeth with pulp exposure. Two months later, the right central incisor teeth reerupted to a normal position and the final aesthetic restorations were done. The left central incisor was spontaneously repositioned with external root resorption, and the team decided to use interim medication (calcium hydroxide) in the root canal for stopping the process of resorption, and by the 9-month follow-up, the process of resorption had been stopped. An MTA plug was placed into the canal, and the final esthetic restorations were done.

Clinical effectiveness of orthodontic miniscrew implantation guided by a novel cone beam CT image-based computer aided design and computer aided manufacturing (CAD-CAM) template

Background

Although miniscrews are widely used in orthodontic treatment as temporary anchorage devices, their correct and safe placement has attracted little attention. This study aimed to introduce a novel cone beam CT (CBCT) image-based computer aided design and computer aided manufacturing (CAD-CAM) template for orthodontic miniscrew implantation and to evaluate the effectiveness of miniscrews implanted under the guidance of this template.

Methods

The CBCT scans of ten patients requiring miniscrews as anchorage were analyzed in NNT software to predetermine the insertion sites of miniscrew implants. The DICOM data of the scans, along with virtual miniscrews acquired in Solidworks software, were imported into Mimics software to construct three-dimensional (3D) images of teeth and bone and to determine the virtual position of miniscrews and 3D virtual templates were designed following consideration of the virtual implantation plans. A STL (Stereolithography) file of the virtual template was output, and the resin template was then fabricated with a stereolithographic appliance (SLA). 24 Miniscrews were then implanted guided by the template and clinical evaluation of their safety and stability, as well as their placement deviations, were made. A dental casts model and cephalometric analysis before and after orthodontic treatment were made to assess the dentomaxillofacial changes.

Results

All 24 miniscrews had no contact with adjacent roots. 18 miniscrews had a grade I safety score and six had a grade II. The miniscrews were stable at 1, 3, 6, and 9 months after implantation, although there was mild inflammation around two miniscrews. Implantation deviation of miniscrew in the crown was (1.03±0.65) and (1.26±0.72) mm in the apex, on average. Satisfactory dentomaxillofacial changes in 10 patients with these 24 miniscrews as anchorage were acquired.

Conclusions

Miniscrews could be implanted in the targeted position safely and precisely when guided by the novel templates, and remained stable during orthodontic treatment. Patients treated with these miniscrews as anchorage in orthodontic treatment acquired satisfactory dentomaxillofacial changes.

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.

Optimal Implantation Site of Orthodontic Micro-Screws in the Mandibular Anterior Region Based on CBCT

Background: To determine the optimal implantation site of orthodontic micro-screws based on cone beam computed tomography (CBCT) analysis in the mandibular anterior tooth region, provide a theoretical basis for orthodontic implant placement and improve post-implantation stability.

Methods: Forty patients who underwent CBCT scanning were selected for this study. CBCT scanning was applied to measure the interradicular distance, buccolingual dimension, labial cortical bone thickness and lingual cortical bone thickness between mandibular anterior teeth at planes 2, 4, 6, and 8 mm below the alveolar ridge crest. The data were measured and collected to obtain a comprehensive evaluation of the specific site conditions of the alveolar bone.

Results: The interradicular distance, buccolingual dimension and labial cortical bone thickness between the mandibular anterior teeth were positively correlated with the distance below the alveolar ridge crest (below 8 mm). The interradicular distance, buccolingual dimension, labial cortical bone thickness, and lingual cortical bone thickness were all greater than those in other areas between the lateral incisor root and canine incisor root 4, 6, and 8 mm below the alveolar ridge crest.

Conclusion: The area between the lateral incisor root and the canine incisor root in planes 4, 6, and 8 mm from the alveolar ridge crest can be used as safe sites for implantation, while 8 mm below the alveolar ridge crest can be the optimal implantation site. An optimal implantation site can be 8 mm below the alveolar ridge crest between the lateral incisor root and the canine incisor root.

Root Resorption of Maxillary Posterior Teeth after Rapid Maxillary Expansion: A Comprehensive Review of the Current Evidence from in-vitro and in-vivo Studies

Background:

The application of heavy forces to the dentition, as those produced during a Rapid Maxillary Expansion (RME), has been associated in the literature with the development of root resorption of maxillary posterior teeth.

Objective:

The aim of the present manuscript was to report the available data from in-vitro and in-vivo studies that can elucidate the biological processes of resorption and repair of radicular cementum after RME.

Methods:

Studies evaluating the occurrence of root resorption after RME by means of histological and radiographic methodology were included. We detailed the changes of the radicular anatomy after RME and provided a synthesis of the most valuable scientific evidence showing the biological processes behind the potential modifications of radicular anatomy. Results. Loss of cementum material and reduction of radicular volumes were seen after rapid maxillary expansion. A small radicular volumetric recovery of anchored teeth occurred after the retention period; this reparative phenomenon was caused by cementum deposition without the reattachment of periodontal fibers, supporting the detrimental effects associated with RR.

Conclusion:

Retention period and the timing of radiographic examination could influence the extension of radicular resorption detected after RME since root resorption and cementum repair may occur at the same time at this stage.

A study of the effects of hydroxyapatite bioceramic extract on Ang/Tie2 system of umbilical vein endothelial cells

OBJECTIVE:

We aimed to investigate the effects of hydroxyapatite bioceramic extract on Ang/Tie2 system and cell proliferation of umbilical vein endothelial cells.

METHODS:

Human umbilical vein endothelial cells (HUVECs) were used in this research. There are two induvial groups, control group and hydroxyapatite bioceramics extract treatment group. Cell Counting Kit-8 (CCK-8) was used to evaluate cell proliferation. Western blot and real time quantitative PCR (Q-PCR) were used to evaluate the protein and mRNA expression levels of Ang1, Ang2 and Tie2 in Ang/Tie2 system, respectively. All the results were statistically analyzed by Spss19.0. All data were presented as mean ± standard error of mean (SEM). Student’s t-test was performed to determine the differences among grouped data.

RESULTS:

Hydroxyapatite bioceramics extract showed no effect on the cell morphology and cell proliferation of HUVECs. Interestingly, we found that both Ang2 and Tie2 protein and mRNA level were markedly increased by hydroxyapatite bioceramics extract.

CONCLUSIONS:

Hydroxyapatite bioceramic extract showed no cytotoxicity to HUVECs, and might regulate vascular remodeling by mediating Ang/Tie2 system.

Analysis of Root Canal Curvature and Root Canal Morphology of Maxillary Posterior Teeth in Guizhou, China

Background

We investigated the root canal curvature and morphology of maxillary posterior teeth in Guizhou, China, to provide references for clinical practice.

Material/Methods

We collected 274 maxillary posterior teeth in Guizhou Province, China. The root canal curvature was observed by X-ray film measurement. Two hundred teeth were selected to make transparent tooth models, and root canal configuration was recorded according to Vertucci classification criteria. The position of the MB2 root canal orifice and the mesiobuccal root canal configuration were observed by micro-computed tomographic (micro-CT) scanning. The t test and the chi-square test were used for statistical analysis.

Results

The root canals of the maxillary posterior teeth showed more significant curvature in the mesiodistal direction than in the buccolingual direction (P<0.05). The MB2 root canal of maxillary molars showed severe bending in the mesiodistal direction: 25.16±6.6 degrees and 28.05±8.65 degrees in first and second molars, respectively. The detection rate of MB2 was 48% in maxillary first molars and 32% in maxillary second molars. The results of micro-CT showed that the vertical distances between the MB2 and MB-P line were 0.64±0.34 mm and 0.57±0.28 mm in first and second molars, respectively.

Conclusions

The root canal morphology and curvature of maxillary posterior teeth varied greatly in the Guizhou population, which increases the difficulty of treatment. It is necessary for clinicians to gain understanding of the root canal and to improve the success rate of root canal therapy.

Characteristics and Dynamics of Full Arch Distalization Using Transpalatal Arches with Midpalatal and Interradicular Miniscrews as Temporary Anchorage Devices: A Preliminary Finite Element Analysis

INTRODUCTION

Miniscrews have proved quite effective in fixed orthodontic treatment. They can be placed in areas like palatal interradicular zones or midpalatal suture. Despite the value of these methods and their ever-increasing use, their characteristics are not assessed before when implanted in palatal interradicular areas or in the midpalatal suture. We aimed to assess, for the first time, the dynamics of full arch distalization using such miniscrews.

METHODS

A 3D model of maxilla with all permanent dentition was created from a CT scan volume. Tissues were segmented and differentiated. Afterward, miniscrews and appliances were designed, and the whole model was registered within a finite element analysis software by assigning proper mechanical properties to tissues and orthodontic appliances. The full arches were distalized using transpalatal arches with miniscrews as anchorage devices (in two different models). The extents of stresses and patterns of movements of various elements (teeth, miniscrews, appliances, tissues) were estimated. Results and Conclusions. Comparing the two models, it is obvious that in both models, the stress distribution is the highest in the TPA arms and the head of the miniscrew where the spring is connected. In comparison with the displacement in the X-axis, the "mesial in" rotation is seen in the first molar of both models. But there is one exception and that is the "mesial out" rotation of the right second molar. In all measurements, the amount of movement in Model 2 (with palatal interradicular miniscrews) is more than that in Model 1 (with midpalatal miniscrew). In the Y-axis, more tipping is seen in Model 2, especially the anterior teeth (detorque) and the first molar, but in Model 1, bodily movement of the first molar is more evident. Along the Z-axis, the mesial intrusion of the first molar and the distal extrusion of this tooth can be seen in both models. Again, the displacement values are higher in the second model (with interradicular miniscrews). In comparison with micromotion and stress distribution of miniscrews, in Model 1, maximum stress and micromotion is observed at the head of the miniscrew where it is attached to the spring. Of course, this amount of micromotion increases over time. The same is true for Model 2, but with a lower micromotion. As for the amount of stress, the stress distribution in both miniscrews of both models is almost uniform and rather severe.

Essential Attributes of Clear Aligner Therapy in terms of Appliance Configuration, Hygiene, and Pain Levels during the Pandemic: A Brief Review

Fixed orthodontic treatment has been compromised at many levels during the pandemic period, as clinics underwent a prolonged lockdown and patients could not be treated regularly. With the end of the pandemic nowhere in sight, may be it is time to put newer tools, such as clear aligner therapy, for better use. Fixed orthodontic appliances by nature are not always self-limiting, which, if left unmonitored over a long period may cause undesirable side effects, pain, and discomfort. The undesired tooth movements that may occur with arch wire-guided mechanics in addition to problems with cut wires or removed brackets may be minimized with the use of aligners. While the benefits of using aligners are for all to see, they do require extensive planning and careful evaluation of the progress. This article reviews the advantages of using aligners during the pandemic period and how it can be beneficial in helping orthodontists resume their practice.

Evaluation of Preosteoblast MC3T3-E1 Cells Cultured on a Microporous Titanium Membrane Fabricated Using a Precise Mechanical Punching Process

The surface topography of Titanium (Ti) combined toughness and biocompatibility affects the attachment and migration of cells. Limited information of morphological characteristics, formed by precise machining in micron order, is currently available on the Ti that could promote osteoconduction. In the present study, a pure Ti membrane was pierced with precise 25 μm square holes at 75 μm intervals and appear burrs at the edge of aperture. We defined the surface without burrs as the “Head side” and that with burrs as the “Tail side”. The effects of the machining microtopography on the proliferation and differentiation of the preosteoblasts (MC3T3-E1 cells) were investigated. The cells were more likely to migrate to, and accumulate in, the aperture of holes on the head side, but grew uniformly regardless of holes on the tail side. The topography on the both surfaces increased osteopontin gene expression levels. Osteocalcin expression levels were higher on the head side than one on the blank scaffold and tail side (p < 0.05). The osteocalcin protein expression levels were higher on the tail side than on the head side after 21 days of cultivation, and were comparable to the proportion of the calcified area (p < 0.05). These results demonstrate the capacity of a novel microporous Ti membrane fabricated using a precise mechanical punching process to promote cell proliferation and activity.

Orthodontic Treatment and Healthcare Goals: Evaluation of Multibrackets Treatment Results Using PAR Index (Peer Assessment Rating)

Background: The evaluation of orthodontic treatment outcomes using an objective method is important in order to maintain high treatment quality and final healthcare of patients. It allows professionals and university students to raise the level of the therapy. The aim of this study was to assess the orthodontic treatment outcomes in an Italian postgraduate School of Orthodontics using Peer Assessment Rating (PAR) Index. Methods: A sample of 50 patients treated in a postgraduate program was randomly selected. PAR index was used to assess pre-treatment and post-treatment study casts by two different examiners. The influence of different variables such as gender, treatment method, and need for extraction was statistically analyzed. Results: The average numerical reduction of PAR between the beginning and the end of the treatment was 18.74 (CI 95% 16.53–20.95), while the percentage reduction was 94.8% (CI 95% 91.91–97.68). All cases improved: 8% of patients resulted in the improved category, while 92% of them were in the greatly improved group. Conclusions: According to PAR index, the results showed that patients received a high-standard therapy. None of the factors studied influenced significantly the treatment outcomes.

Seven-year follow-up of the nonsurgical expansion of maxillary and mandibular arches in a young adult: A case report

BACKGROUND

Palatal expansion treatment has been used to expand the constricted maxillary arch and has become a routine procedure in orthodontic practice over the past decades. However, the long-term stability of expansion in the permanent dentition without a surgical approach is uncertain.

CASE SUMMARY

We present the case of a 15-year-old boy with Class II malocclusion and constricted arches. The patient was treated with rapid palatal expansion (RPE) followed by a fixed orthodontic appliance. A 7-year follow-up evaluation was performed by analyzing cephalometric radiographs, plaster models, and photographs. The patient’s constricted maxillary and mandibular arches were relived after the expansion treatment. A Class I occlusion and normal arch form were established and maintained in the long-term.

CONCLUSION

RPE treatment is successful in solving constricted dental arch in the permanent dentition without a surgical approach. Permanent retention and even occlusal contact help prevent long-term relapse.

Exposure of Biomimetic Composite Materials to Acidic Challenges: Influence on Flexural Resistance and Elastic Modulus

Acidic conditions of the oral cavity, including soft drinks and cariogenic bacteria, represent a damage for restorative biomimetic composite materials. The aim of this study is to assess the influence of two different acidic challenges on the flexural strength and elastic modulus of five composites: x-tra fil (Group 1, XTF), GrandioSO x-tra (Group 2, GXT), Admira Fusion x-tra (Group 3, AFX), VisCalor bulk (Group 4, VCB), and Enamel Plus HRi (Group 5, EPH). Thirty samples for each group were randomly divided and assigned to three different treatments: storage in distilled water as the controls (subgroups 1a-5a), 3 weeks distilled water + 1 week Coca-Cola (subgroups 1b-5b), and 4 weeks Coca-Cola (subgroups 1c-5c). For each subgroup, the flexural strength and elastic modulus were measured using an Instron universal testing machine, and data were submitted to statistical analysis. Considering subgroups B, no material showed a significant difference in the flexural strength with the controls (p > 0.05), whereas for subgroups C, only GXT and VCB showed significantly lower values (p < 0.05). AFX reported the lowest flexural strength among the materials tested. As regards the elastic modulus, no material showed a significant variation after acidic storages when compared with the respective control (p > 0.05). AFX and EPH reported the lowest elastic modulus compared to the other materials. All composites tested showed adequate flexural properties according to the standards, except for AFX. This biomimetic material, along with EPH, might be indicated for V class (cervical) restorations considering the lowest values of elasticity reported.

Perceived Practitioner Barriers to the Management of Orofacial Pain in the Kingdom of Saudi Arabia: A Cross-sectional Study

Background:

Orofacial Pain (OFP) is a group of non-dental painful conditions affecting the oral cavity and facial area.

Objectives:

The objective of this study was to explore which barriers to manage the patient with chronic OFP as perceived by general dentists versus dental specialists and to investigate whether if professionals with degrees from their home country versus another country or number of years of professional experience differ in their perceptions.

Methods:

A closed-end questionnaire was hand-delivered to 600 participants [300 general dentists and 300 dental specialists] in four major provinces in Saudi Arabia. Demographic data were expressed as frequency. Proportional t-tests and chi-square tests were used to analyse intergroup differences. Statistical significance for all analyses was set at P-value < 0.05.

Results:

Overall, the response rate was 56.6% (340/600). Around two-thirds of the participants were general dentists (60.9%), while the remainder were dental specialists (39.1%). There was an obvious consensus by the participants that “Low payment/reimbursement” and “Lack of OFP knowledge” were among the most common barriers (85% and 83.5%, respectively). In contrast, “Legal risks” were the least frequently reported factor (38.8%). The most commonly reported barrier by general dentists was “Shortage of patients/lack of demand;” this was significantly different from the experience of dental specialists (87% vs. 72.2%; P- value < 0.01). In terms of the country of graduation or years of experience, there were no significant differences.

Conclusion:

The study demonstrates the existence of many significant barriers other than OFP knowledge, such as reimbursement, facility and demand that could present obstacles and challenges to the management of OFP by general dentists and dental specialists. Most participants believed that dentists should manage this condition and that OFP courses should be included in the dental school curriculum.

Assessment of stiffness and load deflection of orthodontic miniscrews used for palatal anchorage: An in vitro biomechanical study

OBJECTIVE

The purpose of this study was to evaluate the biomechanical properties of miniscrews of 5 different lengths, 2 different diameters, and different combinations of insertion used for palatal skeletal anchorage.

MATERIALS AND METHODS

Twenty-four different combinations of a total of 120 miniscrews of two different diameters (2.0mm and 2.3mm) and five different lengths (9mm, 11mm, 13mm and 15mm) were tested at different angles of insertion (90° and 45°) and distances from a synthetic bone block (3mm, 5mm, 7mm). Samples were fixed in an Instron Universal Testing Machine and a load was applied in single cantilever mode to the neck of each miniscrew. The stiffness and maximum load before permanent deformation were recorded. Model-based recursive partitioning testing (CART) was used to evaluate differences between groups.

RESULTS

Significantly higher forces were necessary to deform miniscrews of diameter 2.3mm than those of 2.0mm, those inserted at an angle of 45° with respect to 90°, and at smaller distances between the miniscrew neck and block; in addition, the maximum load and stiffness increased with increasing screw length.

CONCLUSION

This in vitro experimental study showed strong correlations between deformation load and miniscrew geometry, insertion angle and distance from the synthetic block, results that should be considered when planning miniscrew insertion in order to reduce the risk of unwanted fracture.

Evaluation of the Relationship Between Maxillary Sinus Wall and Maxillary Canines and Posterior Teeth Using Cone-Beam Computed Tomography

Background

The proximity between the maxillary sinus and dental roots may impede orthodontic tooth movement. This study aimed to explore the relationship between the maxillary sinus wall (MSW) and maxillary canines and posterior teeth using cone-beam computed tomography (CBCT).

Material/Methods

CBCT images (317) were examined for whether the mesial, distal, buccal, and palatal surfaces of the examined root contacted the MSW, and the contact distance of each root surface with the MSW was measured. The effects of age and sex were analyzed using logistic regression and linear regression analyses.

Results

The highest contact ratios with the MSW (ranging from 62.0% to 73.2%) were observed at the palatal root surfaces of the first molar mesiobuccal and distobuccal roots (1M MB and DB), the buccal root surface of the first molar palatal roots (1M P), and the mesial and buccal root surfaces of the second molars (2M), followed by the distal root surface of the second premolars (2PM) and the mesial root surfaces of the 1M MB and P (ranging from 49.2% to 59.3%). At these root surfaces, the contact ratios decreased with age (P<0.05), but the lowest still reached a range of 29.4% to 57.9% in the 30- to 47-year-old group.

Conclusions

The 2PM distal root surface, the 1M MB mesial and palatal root surfaces, the 1M DB palatal root surface, and the 1M P and 2M mesial and buccal root surfaces most frequently contacted the MSW. Clinicians should observe the contact of root surfaces with the MSW, even in aged patients.

Multifunctional Templates for Minimized Osteotomy, Implantation, and Palatal Distraction with a Mini-Screw-Assisted Expander in Schizodontism and Maxillary Deficit

Purpose

Schizodontism is complete separation of a dental germ. It results in a twin tooth and supernumerary teeth. The treatment of transverse constriction in combination with supernumerary dental germs and impacted central incisors can pose a challenge, especially in young patients, when the number of permanent teeth is not adequate to ensure secure anchorage. The use of navigation templates based on three-dimensional X-ray images allows for precise insertion of temporary mini-implants for the acquisition of palatal distractors. In addition, templates allow for minimally invasive biopsies and osteotomies.

Methods

The treatment of schizodontism, dentitio tarda, and transverse constriction is to be assessed as an interdisciplinary method by using mini-screw-assisted devices. Minimized osteotomy of impacted supernumerary teeth or dental implantation can be carried out in a one-step-procedure based on digital preplanning and prefabrication of orthodontic devices.

Results

Multifunctional templates allow for early planning, preoperative fabrication, and intraoral fixation of orthodontic appliances. In the case of an adolescent patient, a sustainable, interdisciplinary treatment concept could be demonstrated that shows age-appropriate gnathological development and stable growth conditions over a follow-up period of 10 years.

Conclusion

One can likely assume that multifunctional templates allow for minimally invasive one-step surgeries as an interdisciplinary tool between orofacial surgery and modern orthodontics.

Influence of General Mineral Condition on Collagen-Guided Alveolar Crest Augmentation

The local regeneration of bone defects is regulated by general hormone, enzyme, ion, and vitamin levels. General diseases and dysregulation of the human mineral system can impact this process, even in alveolar crest. The aim of this study is to investigate a relation between bone density, measured in two-dimensional X-rays, and general mineral condition of patients. The study included 42 patients on whom tooth extractions were performed. Data were divided into two groups: the region where collagen scaffold (BRM) was used and the reference region of intact normal bone (REF). Two-dimensional intraoral radiographs were taken in all cases just after the surgery (00 M) and 12 months later (12 M). Thyrotropin (TSH), parathormone (PTH), Ca²⁺ in serum, HbA1c, vitamin 25(OH)D₃, and spine densitometry were checked. Digital texture analysis in MaZda 4.6 software was done. Texture Index (TI: BRM 1.66 ± 0.34 in 00 M, 1.51 ± 0.41 in 12 M, and REF 1.72 ± 0.28) and Bone Index (BI: BRM 0.73 ± 0.17 in 00 M, 0.65 ± 0.22 41 in 12 M, and REF 0.80 ± 0.14) were calculated to evaluate bone regeneration process after 12 months of healing (TI (p < 0.05) and BI (p < 0.01) are lower in BRM 12 M than in REF). This showed a relation between BI and TSH (R² = 26%, p < 0.05), as well as a between BI and patient age (R² = 65%, p < 0.001), and a weak relation between TI and TSH level (R² = 10%, p < 0.05). This study proved that a collagen scaffold can be successfully used in alveolar crest regeneration, especially in patients with a high normal level of TSH in the middle-aged population.

Imaging Software Programs for Reliable Mathematical Measurements in Orthodontics

AIM

To evaluate the reliability of linear and angular measurements taken using different software programs in orthodontics.

MATERIALS AND METHODS

A sample of four software programs from different manufacturers, namely MicroDicom viewer, Photoshop® CS3, AutoCAD®, and Image-Pro®, were used for measuring the geometric features of four types of miniscrews from different manufacturers. Each miniscrew type presented a group: Group I, Tomas® (Dentaurum, Ispringen, Germany); Group II, HUBIT® (HUBIT, Gyeonggi-do, Korea); Group III, AbsoAnchor® (Dentos, Daegu, Korea); and Group IV, Creative (Creative, Zhejiang, China). Measurements of apical face angle, thread angle, lead angle, flank, pitch depth, and width were taken on 45 × magnification scanning electron microscope images of the shafts of the miniscrews. One assessor measured the seven geometric features for the four types of miniscrews using the four software programs twice in two sessions separated by a three week interval.

RESULTS

Pairwise comparisons, for each of the four miniscrew groups, showed that the only common result observed was the significant difference (p < 0.001) between measurements of flank taken by the four software programs. When measurements of the four types of miniscrews were pooled into one group, a high degree of intra-rater reliability (ICC range from 0.9 to 1.0) for all the seven geometric features was found with all the four software programs. The paired t-test showed insignificant difference (at p ≤ 0.05) between the first and second measurements, except for a few measurements including pitch width measured by Image-Pro® (p = 0.012), MicroDicom (p = 0.023), and Photoshop® (p = 0.001).

CONCLUSIONS

Results did not give absolute superiority to one software program over the others and suggested an assessor effect. Assessor estimates could have been affected, among other factors, by the design of the miniscrews and the technical features of the software programs.

Minimally Invasive Diastema Restoration with Prefabricated Sectional Veneers

This case report presents a new technique for sectional veneer fabrication and diastema restoration with a prefabricated composite veneer. For the purpose of diastema restoration, a prefabricated sectional veneer provides the same benefits of a traditional ceramic sectional veneer (highly esthetic restoration with no need for tooth preparation) but involves a less technically demanding and time-consuming clinical procedure and a less delicate restoration with a reduced risk of accidental breakage and post-bonding crack formation. The technique presented in this case report bridges the gap between a direct and indirect technique for diastema restoration and introduces a new treatment option to close anterior spacing with a highly esthetic sectional veneer in a predictable and timely manner.

Characterization of the Cellular Reaction to a Collagen-Based Matrix: An In Vivo Histological and Histomorphometrical Analysis

The permeability and inflammatory tissue reaction to Mucomaix^® matrix (MM), a non- cross-linked collagen-based matrix was evaluated in both ex vivo and in vivo settings. Liquid platelet rich fibrin (PRF), a blood concentrate system, was used to assess its capacity to absorb human proteins and interact with blood cells ex vivo. In the in vivo aspect, 12 Wister rats had MM implanted subcutaneously, whereas another 12 rats (control) were sham-operated without biomaterial implantation. On days 3, 15 and 30, explantation was completed (four rats per time-point) to evaluate the tissue reactions to the matrix. Data collected were statistically analyzed using analysis of variance (ANOVA) and Tukey multiple comparisons tests (GraphPad Prism 8). The matrix absorbed the liquid PRF in the ex vivo study. Day 3 post-implantation revealed mild tissue inflammatory reaction with presence of mononuclear cells in the implantation site and on the biomaterial surface (mostly CD68-positive macrophages). The control group at this stage had more mononuclear cells than the test group. From day 15, multinucleated giant cells (MNGCs) were seen in the implantation site and the outer third of the matrix with marked increase on day 30 and spread to the matrix core. The presence of these CD68-positive MNGCs was associated with significant matrix vascularization. The matrix degraded significantly over the study period, but its core was still visible as of day 30 post-implantation. The high permeability and fast degradation properties of MM were highlighted.

The ideal insertion angle after immediate loading in Jeil, Storm, and Thunder miniscrews: A 3D-FEM study

OBJECTIVE

The miniscrew is effectively used to provide additional anchorage for orthodontic purposes. The aim of this study was to identify an optimal insertion angle for Jeil, Storm, and Thunder miniscrews on stress distribution at the bone miniscrew interface.

MATERIALS AND METHODS

To perform 3-dimensional finite element model analysis, a 3-dimensional model with a bone block was constructed with type D2 of bone quality, and with miniscrews of Storm, Thunder, Jeil, with the diameter of 2, 1.5. 1.6mm and length 15.9, 12.4, 14.4mm respectively. The miniscrews were inserted at 15° 30°, 45°, 60°, 75° and 90° to the bone surface. A simulated horizontal orthodontic force of 200 gram was applied to the centre of the miniscrews head in all models, and stress distribution and its magnitude were evaluated with a 3-dimensional finite element analysis program.

RESULTS

In the cancellous bone, minimum stress was found at placement angles of 90° for Jeil and Storm, which was 0.37 and 0.39MPa respectively, and 15° for Thunder, which was 0.85MPa. The maximum von Mises stresses in the cancellous bone for Jeil was at 60°, which was 0.92MPa, and for Thunder at 90°, which was 1.3MPa.

CONCLUSION

Each miniscrew has an ideal insertion angle, optimal insertion positions were found within 90° for Jeil and for Storm but 15° for Thunder. Clinical significance 3-dimensional finite element analysis confirmed that each miniscrew has an ideal insertion angle according to its characteristics.

Evaluation of the long-term stability of micro-screws under different loading protocols: a systematic review

The aim of this systematic review was to investigate the association between the different factors of loading protocols and the long-term stability of micro-screws from biomechanical and histological viewpoints. Searches were performed on PubMed, Embase, Cochrane Library, Wanfang and CNKI databases for animal experiments comparing loading protocols and the long-term stability of micro-screws. Among 1011 detected papers, 16 studies met the eligibility criteria and were selected for analysis. Most studies showed medium methodological quality for evaluation of micro-screws' long-term stability. Five studies reported that loading would not destroy the long-term stability of micro-screws. Three studies indicated that low-intensity immediate loading or a 3-week minimal healing time was acceptable. Two studies reported that the loading magnitude was a controversial issue with regard to the micro-screws' long-term stability. Two studies suggested that counterclockwise loading could decrease the long-term stability of micro-screws. In conclusion, immediate loading below 100g force, healing time greater than 3 weeks, regular loading below 200g force and a clockwise direction of force supported the long-term stability of micro-screws. Further studies relating to the combination of varying loading conditions will be needed.