Comparative analysis of the biomechanical behavior of the maxillary central incisors restored with glass fiber post and cast metal post and core submitted to orthodontic forces: A study with finite elements.

INTRODUCTION: Different types of intraradicular restorations and their insertion have an impact on teeth biomechanics. This study aimed to analyze the biomechanical behavior of maxillary central incisors restored with glass fiber post (GFP) and cast metal post and core (CMP) subjected to buccolingual and mesiodistal orthodontic forces using the finite element method. METHODS: Two models of the maxillary central incisor with periodontal ligament, cortical bone, and trabecular bone were made. One of the models included intraradicular restoration with GFP, whereas, in the other, the incisor was restored with CMP. After creating the tridimensional mesh of finite elements, applying 2 orthodontic forces were simulated: 65 g of buccolingual force and 70 g of mesiodistal force. The forces were applied parallel to the palatal plane in the region of the bracket slot, located 4 mm to the incisal edge. RESULTS: The maximum stresses generated in the GFP-restored root were 3.642 × 10-1 MPa and 4.755 × 10-1 MPa from the buccolingual and mesiodistal forces, respectively. Likewise, the stresses in the CMP restored root were 2.777 × 10-1MPa and 3.826 × 10-1MPa. The radicular area with higher stress on both models was located in the cervical third: on the buccal surface when the buccolingual force was applied and on the mesial surface when the mesiodistal force was applied. The highest stress levels were found on the CMP structure. CONCLUSIONS: The incisor restored with cast metal post revealed lower stress values transferred to the root than the one restored with GFP. The stresses on the structure of the GFP were lower and more homogeneous than the ones found on the cast metal post. The difference among the stress values in the materials is within a safe margin for using both materials in relation to orthodontic forces.

Eyes wide open to avoid misleading diagnosis and treatment planning.

INTRODUCTION: The treatment of impacted and transposed teeth is a challenge for clinical practice. A precise assessment of the relative position of the transposed tooth could lessen the risks of adverse effects, such as root resorption and periodontal problems. DESCRIPTION OF THE CASE: An 18-year-old patient went to the Orthodontic Department of the Federal University of Juiz de Fora, Brazil for a re-evaluation of the orthodontic treatment to which she had been receiving since the age of 12. Attempted traction of an impacted maxillary canine resulted in root resorption, marked mobility and alteration in the position of adjacent teeth as well as loss of alveolar bone in the anterior region of the maxilla. This tooth was not only partially transposed, but it also had ankylosis, external and internal tooth resorption, which indicated the need for tooth extraction. A change was made to the treatment plan, with the extraction of the canine, bone graft and mesial movement of the posterior teeth. RESULTS: All the spaces were closed at the end of treatment, with normal overbite and overjet. At the follow-up, the teeth position, the shape of dental arches, disocclusion guides and dental occlusion were preserved. The bone graft in the maxilla showed height and mineral density stability. CONCLUSION: The presence of the maxillary permanent canines in the dental arch is important for both aesthetics and a functional occlusion. However, despite the importance of their maintenance in the arch, it is well advised that each case be analysed individually.

Orthodontic treatment after intrusive dislocation and fracture of the maxillary central incisors.

The treatment for intrusive dislocation is a clinical challenge and must be started soon after the intrusion injury. The affected tooth or teeth must be extruded by using light forces. This case report of traumatic intrusion of permanent central incisors aims to describe and discuss the process of repositioning the teeth in the dental arch. After a domestic accident, a 10-year-2-month-old boy suffered 11-mm intrusion of the maxillary central incisors along with enamel-dentin fracture and subluxation of the maxillary lateral incisors. Treatment started 2 days after the incident with an orthodontic extrusion of the maxillary central incisors with a fixed edgewise standard appliance. Orthodontic arches were used, and the force vectors were directed to the desired locations for the repositioning of the teeth. The treatment for extrusion and stabilization of the maxillary central incisors lasted 5 months and 22 days. Orthodontic traction with a fixed appliance is an effective procedure for the extrusion of both permanent maxillary central incisors intruded after trauma. Correct diagnosis, a short period between the trauma and the beginning of treatment, and appropriate mechanics were determining factors for a successful treatment.

Spontaneous remission of internal root resorption during orthodontic treatment: A clinical follow-up report.

Internal root resorption (IRR) is a pathologic process that occurs because of external stimuli that affect the pulp and result in the loss of dentinal tissue. The occurrence of IRR is considered relatively rare, and the etiology is not fully understood, although trauma is believed to be the main etiologic agent. The current study presented a case report of spontaneous remission of an IRR lesion diagnosed during orthodontic treatment. The lesion was characterized by a circular and delimited radiolucent image, located in the apical third of the root canal of the maxillary right lateral incisor diagnosed during orthodontic treatment. After the diagnosis, clinical and radiographic follow-up was performed without any intervention. The follow-up radiographic images showed loss of contour definition and reduction in the size of the lesion. At the end of orthodontic treatment, 27 months after diagnosis, the space of the lesion had been filled by tissue with similar radiopacity to the adjacent dentin, and the tooth did not change its color and response to mechanical and thermal stimuli. Eight years after the end of the treatment, the maxillary right lateral incisor still presented normal responses to vitality tests and color stability; therefore, it was impossible to notice the root canal space. The reported patient presents a possible behavior of the IRR characterized by spontaneous remission of the lesion. However, nonendodontic treatment after diagnosis should not be the routine therapy adopted for IRR because of the potential risk to the tooth.

Tooth root and alveolar bone grey values derived from cone-beam CT imaging in maxillary incisor teeth with and without apical root resorption.

INTRODUCTION: In orthodontic treatment, an increased bone mineral density of the alveolar bone is considered as a risk factor for apical root resorption (ARR), whereas the mineral density of cementum has been associated with root protection against resorption. METHODS: This study aimed at evaluating the grey values (GVs) of the apical third of the root and of the alveolar bone adjacent to maxillary incisors with and without ARR in orthodontic patients. Twenty-one patients under treatment who presented one incisor with ARR and its corresponding contralateral without ARR were selected and submitted to cone-beam computed tomography. GVs were evaluated on the images obtained of four areas of the apical third of the root and of four areas of the adjacent alveolar bone. RESULTS AND CONCLUSIONS: The radicular tissue of the apical third of the incisors with ARR showed greater root GV (p < .05) than that of the incisors without ARR. Supra-apical alveolar bone exhibited greater GV in the incisors without ARR than incisors with ARR (p < .05). Root GV was not associated with root protection, but rather seemed to have facilitated the process of resorption. The GV of the lingual bone was associated with a higher progression of ARR in the incisors.

Use of gray values in CBCT and MSCT images for determination of density: influence of variation of FOV size.

PURPOSE: To determine the effect of field of view (FOV) size on gray values in cone beam computed tomography (CBCT) and multislice computed tomography (MSCT) images. MATERIAL AND METHODS: A phantom made up of 3 cylinders containing distilled water, plaster, and motor oil was constructed and inserted into an acrylic cylinder filled with distilled water. The phantom was scanned with a CBCT and MSCT device using 3 FOV sizes. Gray value of each material was evaluated in 40 axial slices, and the comparison between the results obtained with the same FOV size was made. RESULTS: In CBCT examinations, there was significant difference between the gray values of different FOVs for the 3 materials. In the MSCT, there was significant difference for the oil. Gray values showed significant difference between the CBCT and MSCT examinations for the 3 materials in the 3 different FOV sizes. CONCLUSIONS: Gray values determined in CBCT images are significantly influenced by the FOV size. Although the gray values obtained in MSCT have shown statistically significant differences between some acquisitions, the analysis of those differences seems to indicate low clinical relevance.

Civil liability of orthodontists and aligner manufacturers in the treatment with orthodontic aligners.

INTRODUCTION: The use of clear aligners as an alternative to fixed orthodontic appliances has become popular due to the aesthetic demands of adult patients seeking orthodontic treatment. However, orthodontists' lack of knowledge about the legal consequences of their activities, and the lack of solid scientific evidence raise concerns regarding civil liability in this type of treatment. Marketing campaigns of manufacturing companies often exaggerate promises of results, and ignore the lack of scientific evidence. Patients, as consumers, are protected by the Consumer Protection Code, whereas orthodontists are considered treatment providers. Therefore, they can be held liable for damage caused to patients, whether by subjective or objective fault. OBJECTIVE: This article aims to identify the civil responsibilities of orthodontists and aligner manufacturing companies, by means of a literature review, providing basic legal guidance to help professionals protect themselves from possible lawsuits related to treatment with orthodontic aligners. CONCLUSIONS: The study highlights the importance of knowledge of legal notions in treatments with orthodontic aligners by orthodontists, who should legally safeguard themselves through individual written contracts, avoiding obligation of results. In addition, in cases of legal claims, it is possible that the manufacturing companies are jointly and severally liable for possible damages claimed by the patient.

Anteroposterior condylar position: a comparative study between subjects with normal occlusion and patients with Class I, Class II Division 1, and Class III malocclusions.

BACKGROUND: The present study aimed to determine and compare the anteroposterior position of the condyle in the mandibular fossa between groups of asymptomatic subjects with normal occlusion and asymptomatic subjects with Class I, Class II Division 1, and Class III malocclusions. MATERIAL AND METHODS: Thirty persons with normal occlusion, 30 with Class I malocclusion, 30 with Class II Division 1, and 30 with Class III had computed tomography scans of their temporomandibular joints. The anterior joint space/posterior joint space (AJS/PJS) ratio was determined for the right and left joints. The paired t test was used to analyze the AJS/PJS ratio between both sides for each group. The ANOVA test was applied to verify the differences between the groups for the measurements of the right and left sides. In case the ANOVA test confirmed significance, the Dunnett's t test was performed to compare the groups of malocclusion with that of normal occlusion. RESULTS: The paired t test between the AJS/PJS relationships in the right and left sides showed the following p values: Class I (0.168), Class II Division 1 (0.662), Class III (0.991), and normal occlusion (0.390). The ANOVA test showed a p value of 0.445 for the comparisons of the right side and 0.040 for the left side. The Dunnett's t test demonstrated a statistically significant difference between the Class II group and the normal occlusion group (p value of 0.026) in the joints of the left side. CONCLUSIONS: Bilateral symmetry and lack of condyle centralization were common characteristics among all groups. The greatest condylar decentralization was observed in the Class II group, whereas the least condylar decentralization was found in the normal occlusion group.

Apical root resorption: the dark side of the root.

INTRODUCTION: The diagnosis of apical root resorption is usually based on routine radiographs. However, these methods are limited because the images reflect the superimposition of the whole root structure and can lead to underestimation of the extent of apical root resorption. In this study, we aimed to determine the lengths of the labial and lingual surfaces of incisors with apical root resorption and compare them with the longest radicular length obtained on sagittal images of cone-beam computed tomography, and to create a qualitative visual scale of the different patterns of apical root resorption. METHODS: Eighty-two incisors with apical root resorption from 25 patients had their labial and lingual root surfaces and the longest radicular lengths determined in the sagittal plane and compared. Five orthodontists, at 2 times, classified the images of each incisor according to a visual scale developed by the authors. RESULTS: There was no significant difference between the labial and lingual surfaces; however, the longest radicular length was significantly greater than the shortest surface length. The visual scale showed intraobserver agreement of 0.615 and interobserver agreements of 0.74 and 0.52 at both times, respectively. CONCLUSIONS: The difference between the longest and shortest root lengths suggests that radiographic superimposition underestimates the extent of the resorption lesion. The proposed visual scale showed a frequency of agreement above 65% and a coefficient of reproducibility varying from moderate to substantial.

Elementary school teachers' knowledge and attitudes toward emergency management of traumatic dental injuries.

The consequences of traumatic dental injuries can be even more serious when their emergency management procedures are inadequate. Since traumatic accidents frequently occur at school, it is crucial that teachers be knowledgeable enough to assist an injured child. This study aimed to assess the knowledge and attitudes of the elementary school teachers of a Brazilian city toward dental trauma in permanent teeth, and its emergency practices. A combination of convenience and snowball sampling methods was used. An online questionnaire was distributed through social media, consisting of three parts: demographic characteristics and professional information; previous experiences and attitudes toward dental trauma; teachers' knowledge of this subject. Descriptive and statistical analyses were carried out. Pearson chi-squared test (p < 0.05) was used. A total of 217 teachers participated in the study. The power of the sample was 95%. Half of the teachers had already witnessed a dental trauma incident involving students, and 70.5% never received any information on the subject. The teachers who were provided previous information were the ones who opted to search for the tooth fragment (p=0.036) in cases of crown fracture, and for the lost tooth (p = 0.025) in cases of avulsion. They were also the ones who chose to wash the tooth in running water (p = 0.018), and look for a dentist in the first 30 or 60 minutes after the trauma (p = 0.026). Most of the teachers assessed did not have adequate knowledge of dental trauma. Having previous information was associated with more assertive practices in trauma management.

Traumatic dental injuries in children: experience during the Covid-19 pandemic and parents' knowledge about their management.

The social isolation measures adopted during the critical phase of the COVID-19 pandemic led children to spend most of their time at home. Isolation may alter the pattern of traumatic dental injury occurrences, inasmuch as studies point out that most traumatic accidents occur at home. Considering this scenario and the influence of emergency management on the prognosis of the injury, the aim of this study was to evaluate the experience of traumatic dental injuries in children before and during the pandemic, and the knowledge of this topic by the children's guardians. This cross-sectional study was conducted with guardians of children aged 0 to 6 years, residing in Juiz de Fora, MG, Brazil. The guardians answered an online questionnaire addressing personal information, traumatic dental injury experience before and during the pandemic, and knowledge of this topic. Descriptive and statistical analyses were performed using Pearson's chi-square test at a 5% significance level. The total sample consisted of 343 volunteers. A total of 95 and 92 injuries were reported before and during the pandemic, respectively; the home was the place of greatest occurrence. Most volunteers (88.1%) agreed that traumatic dental injuries are emergency situations, and were aware that the tooth/fragment had to be taken to the dentist after a fracture or avulsion (97.4%). This study revealed that the traumatic dental injury experience was similar before and during the pandemic, and that the volunteers had satisfactory knowledge, especially in recognizing the importance of immediate attention for a more favorable prognosis of these injuries.

The role of orthodontic tooth movement in bone and root mineral density: a study of patients submitted and not submitted to orthodontic treatment.

BACKGROUND: Orthodontic force application to the teeth is responsible for a series of biological responses in the bone and dentin, which lead to some alterations of the mineral density of the tissues. Our objective was determine, through cone-beam computed tomography (CBCT), the mineral density of the apical third of the roots of the upper central incisors and of the periapical bone portion surrounding these teeth, in patients submitted to orthodontic treated and untreated individuals. MATERIAL/METHODS: 30 untreated individuals and 15 treated ones (treatment cessation at least 1 year before the study) underwent CBCT. Mineral density was assessed in the apical third of the root of the upper central incisors and in the alveolar bone in the periapical region of these teeth. In order to reduce CBCT-related mineral density variability, we standardized the cone-beam tomography device, the image-acquisition settings and the field of view positioning and size. Student's t test was used for the analyses. RESULTS: bone mineral density (BMD) and root mineral density (RMD), in Hounsfield Units, were 674.84 and 1282.26 for the untreated group and 630.28 and 1370.29 for the treated group, respectively. The differences between the group means were statistically significant for RMD (p<0.05). CONCLUSIONS: untreated individuals had a significant lower mean RMD in comparison with those submitted to orthodontic treatment.

The absence of proximal contact point on periodontal parameters of teeth moved into extraction sites.

The aim of study was to evaluate periodontal conditions of upper canines and second premolars with and without proximal contact of individuals undergoing orthodontic treatment associated to extractions of the upper first premolars. The study selected upper canines and premolars of individuals undergoing orthodontic treatment without extractions (30 hemiarches - control group), or with extraction of the upper first premolars and whose canines and second premolars had interproximal contact (16 hemiarches - group 1) or diastema (17 hemiarches - group 2). Clinical (plaque index, probing depth, gingival bleeding index, height of the gingival margin, clinical attachment loss and gingival clefts) and radiographic (crest height, bone height and bone-crest discrepancy) parameters of the distal surfaces of canines and mesial surfaces of premolars were evaluated. Group 1 had worse results when compared to the control group for the levels of plaque in canines and premolars and for probing depth in canines (distal and mean) and in premolars (lingual and mean), as well as increasing tendency of clinical attachment loss (lingual and mean) in premolars. Plaque level in canines in group 1 was also significantly higher than in group 2. There was no difference between group 2 and the control group. The lack of proximal contact between canines and second premolars did not significantly affect their periodontal characteristics.

Effect of Yellow Propolis on Biocompatibility of Cements: Morphological and Immunohistochemistry Analysis.

OBJECTIVE: The focus of this study was to evaluate the biocompatibility of ionomer cements modified with ethanolic extracts of propolis (EEP) in different concentrations and time intervals. MATERIALS AND METHODS: In total, one hundred and thirty-five male Wistar rats were randomized into nine groups: Control, Groups Meron, and Groups Ketac (conventional, and added with 10, 25, 50% EEP, respectively). Histological analyses of inflammatory infiltrate and collagen fibers, and immunohistochemistry of CD68+ for macrophages (MOs) and multinucleated giant cells (MGCs) were performed. STATISTICAL ANALYSIS: Data were analyzed using the Kruskal-Wallis and Dunn (p < 0.05) tests. RESULTS: Intense inflammatory infiltrate was demonstrated in the cements with 10% EEP at 7 days and 15 days (p < 0.05), only Group Ketac 10% EEP (p = 0.01) at 30 days. A smaller quantity of collagen fibers was observed in the cements with 10% EEP (p = 0.01) at 7 days, and Group Meron 10% EEP (p = 0.04) at 15 days. MOs and MGCs showed significant difference for the cements with 10% EEP (p = 0.01) at 7 and 15 days. At 30 days, MOs persisted in the Groups with 10% EEP. CONCLUSIONS: The concentration of 10% EEP had the greatest influence on the inflammatory and tissue repair processes. The concentrations of 25 and 50% EEP demonstrated biocompatibility similar to that of cements that did not receive EEP.

Salivary alpha-amylase activity: a possible indicator of pain-induced stress in orthodontic patients.

INTRODUCTION: Pain, a common experience reported by orthodontic patients, has its intensity assessed with the help of subjective scales, which have a limited and disputable value. Such unpleasant experience, which may raise stress levels, is reflected by an increase in the salivary concentration of alpha-amylase. OBJECTIVE: Assess the correlation between the salivary levels of alpha-amylase and pain intensity reported by patients during orthodontic treatment. PATIENTS: Twenty male patients (11-37 years of age) were assessed daily, before treatment, after bracket bonding, and after initial arch wire insertion. DESIGN: Saliva was sampled for alpha-amylase analysis, and pain intensity was measured with the visual analog scale. RESULTS: There was no correlation between alpha-amylase concentrations in the saliva and pain intensity, although the patients had a significant and progressive increase of alpha-amylase levels during the assessment period. CONCLUSIONS: The findings may reflect the psychological stress caused by the presence and activation of the fixed appliance.

Analysis of Chlorhexidine Modified Cement in Orthodontic Patients: A Double-Blinded, Randomized, Controlled Trial.

OBJECTIVES: The aim of this study was to evaluate the microbiological and mechanical properties of glass ionomer cement (GIC) modified by chlorhexidine (CLX) for the purpose of cementing bands to the teeth of orthodontic patients. MATERIALS AND METHODS: Ten patients, between the ages of 19 and 33 years, in the initial stage of orthodontic treatment, were randomly designated to two groups using the split-mouth design (n = 10). One group (GICEX) had bands cemented with GIC modified by CLX and a Control group (GIC), evaluated at time intervals before (T0), 3 months (T3), and 6 months (T6) after cementation. Total microbiological counts were performed, and color stability of tooth enamel, salivary pH, and the adhesive remnant index (ARI) were evaluated. STATISTICAL ANALYSIS: The Friedman and Dunn's tests, Mann-Whitney, one-way analysis of variance, and Tukey, and paired and non-paired t-tests (p< 0.05) were used. RESULTS: In T3, there was evidence of significant reduction in the quantity of colony forming unit (CFU) in GICEX group in comparison with the Control (p = 0.041). In T6, the quantity of CFU was similar to the quantity in T3 and significantly different to control (p = 0.045); Control group demonstrated a similar quantity of CFU between the experimental time intervals (p = 0.066). Salivary pH demonstrated significant difference only between the time intervals T0 and T6 (p = 0.022). The tooth enamel color (p = 0.366) and ARI (p = 0.343) values demonstrated no significant changes. CONCLUSION: The incorporation of CLX into GIC demonstrated effective antibacterial action, allowed a good bond of the cement to the enamel, a high rate of survival of the bands, did not change the color of the tooth enamel, and maintained the salivary pH at physiological levels.

Corrosion resistance assessment of nickel-titanium endodontic files with and without heat treatment.

OBJECTIVES: The aim of this study was to evaluate the corrosion resistance of heat-treated (Reciproc and WaveOne) and non-heat-treated (ProTaper and Mtwo) superelastic nickel-titanium endodontic files when immersed in a 5.25% sodium hypochlorite solution. MATERIALS AND METHODS: Anodic polarization curves were obtained with potential sweeps that began at the open circuit potential or corrosion potential (Ecorr). The pitting potential (Epit) was identified on the anodic polarization curve as the potential at which a sudden increase in current was observed. The micromorphology of the 28 tested files was analyzed before and after the electrochemical assay using scanning electron microscope (SEM). The data were analyzed using 1-way analysis of variance with the post hoc Bonferroni test (for Ecorr) and the Student t-test for independent samples (for Epit). RESULTS: The mean Ecorr values were 0.506 V for ProTaper, 0.348 V for Mtwo, 0.542 V for Reciproc, and 0.321 V for WaveOne files. Only WaveOne and Protaper files exhibited pitting corrosion, with Epit values of 0.879 V and 0.904 V, respectively. On the SEM images of the ProTaper and WaveOne files, cavities suggestive of pitting corrosion were detected. CONCLUSIONS: Signs of corrosion were observed in both heat-treated and non-heat-treated files. Of the evaluated files, WaveOne (a heat-treated file) and ProTaper (a non-heat-treated file) exhibited the lowest corrosion resistance.