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.

Laypeople's and dental students' perceptions of a diastema between central and lateral incisors: Evaluation using scanpaths and colour-coded maps.

OBJECTIVE: This study aimed to use eye tracking to analyse people's visual perceptions of smiles with a diastema between the maxillary central and lateral incisors, based on different categories of observers. SETTING AND SAMPLE POPULATIONS: An image of a diastema between the maxillary central and lateral incisors was shown to dental students and laypeople. MATERIALS AND METHODS: Our null hypothesis was that there would be no difference in the visual perception of the different graduations of diastemas between the two groups. The diastemas were edited in Photoshop® to gradually increase the distance between the maxillary central and lateral incisors from no diastema to 1.5 mm and 3.5 mm diastemas. These diastemas were evaluated by using a TheEyeTribe© tracker in conjunction with OGAMA© 5.0 software. A total of 37 dental students and 33 laypeople looked at eight randomly arranged images of smiles. The data were analyzed using color coded maps, scanpaths, and the Kruskal-Wallis test with a level of significance of 5%. RESULTS: Laypeople tended to observe the eyes, focusing more on the right than the left, and spent less time focusing on the diastema region than did the dental students. There were differences for the same magnitude of diastema within participant groups. As the width of the diastema increased, both students and laypeople focused more on the diastema region. CONCLUSIONS: The two groups of evaluators presented different perceptions of smiles in cases of diastema between the maxillary central and lateral incisors when evaluated using eye-tracking.

Classification of the midpalatal suture maturation in individuals older than 15 years: a cone beam computed tomographic study.

PURPOSE: The aim of this study was to classify the maturation of the midpalatal suture (MPS) in a sample of individuals aged 15 years and older. METHODS: Tomographic images in axial sections of the MPS of 289 female individuals and 198 male individuals aged between 15 and 40 years were analyzed and classified in stages of maturation (A, B, C, D, and E), stage A represents the earliest maturation stage of the suture and in stage E the fusion of the MPS has occurred in the maxilla. The Kruskal-Wallis and Student-Newman-Kells tests were used to compare the chronological ages among different maturation stages. Spearman's correlation coefficient was used to assess the correlation between patient's age and the maturation stages of the MPS. RESULTS: Stage A was not observed in the sample. Stages B and C represent, respectively, 1.03% and 34.09% of the sample, stage D was found in 16.63% of the sample while stage E was the most prevalent stage found (48.25%). For females, it was revealed no statistically significant difference in the mean ages among stages C, D and E (p = 0.4753). For males, a statistically significant difference was observed, with the mean age of individuals in stages D and E of the MPS maturation higher than in other stages (p = 0.0001). There was a significant, but weak, correlation between patient's age and the maturation stages of the suture (rs = 0.11/p = 0.01). CONCLUSION: No individuals in stage A of suture maturation were found and stage B was identified in only 1% of the sample. The majority of the patients (64.88%) presented at least partial fusion of the MPS (stages D and E).

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.

Evaluation of the vertical accuracy of bracket placement with the Boone gauge.

INTRODUCTION: In this study, we aimed to evaluate the influence of clinical experience and the type of tooth (incisors, canines, and premolars) on the vertical accuracy of bracket placement with the Boone gauge. METHODS: For this analysis, 4 groups were defined. Group 1 was composed of undergraduate students from the dental school with no previous experience in bonding orthodontic attachments; group 2 was composed of graduate students in the dental school; group 3 consisted of orthodontists with a maximum of 5 years of clinical experience; and group 4 comprised orthodontists with more than 5 years of clinical experience. Each group included 6 participants. A typodont was simulated with a Class I crowded malocclusion that reproduced the same occlusal characteristics for all groups to be bonded. All participants were instructed to bond 0.022 × 0.028-in edgewise brackets on the labial surfaces of the maxillary and mandibular incisors, canines, and premolars at a height of 4 mm from the incisal edge or the labial cusp tip. After each bonding procedure, all teeth were photographed after being removed from the typodont and positioned in a stabilizing device adapted to a camera stand. RESULTS: The analyses of the variations showed that group 1 had the closest mean to 4 mm. However, this group also showed the greatest variance (0.433) (P <0.001). The smallest variations were observed in group 2 (variance, 0.093), followed by group 4 (variance, 0.094). The comparison of the means obtained in the groups of teeth at 4 mm demonstrated that the incisors showed a statistically significant difference (P <0.001), whereas canines (P = 0.133) and premolars (P = 0.913) did not. CONCLUSIONS: Operators are prone to fail in the placement of orthodontic attachments with the Boone gauge, despite their clinical experience in orthodontics. In the comparison of the groups of teeth, the incisors showed a statistically significant difference in relation to the height suggested for bracket placement with the Boone gauge.

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.

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.

Characteristics of patients seeking orthodontic retreatment.

BACKGROUND: The aim of this cross-sectional study was to investigate patients' experiences with previous orthodontic treatment for those seeking retreatment, and their expectations and motivation for doing so. METHODS: A total of 72 patients were invited to answer an anonymous questionnaire. Of these, 36 (13 men and 23 women, mean age 26.3 ± 5.8 years) were seeking retreatment (study group), and 36 (13 men and 23 women, mean age 25.5 ± 6.8 years) were seeking treatment for the first time (control group). Casts from both groups were assessed with the index of complexity, outcome, and need (ICON) score, to objectively determine the treatment need and complexity. Student`s t test for independent samples, and paired Student`s t test, were performed for comparisons between the retreatment and control groups, and between retreatment and previous treatment, respectively. RESULTS: There was no statistically significant difference between retreatment patients` motivation for the previous treatment and motivation for the retreatment. However, the mean visual analog scale (VAS) scores for motivation differed significantly between the retreatment and control groups (73.8 ± 23.9 and 87.5 ± 14.5, respectively). The mean ICON score of the retreatment group was lower than that for the control group (25 ± 14 and 31 ± 16, respectively). CONCLUSIONS: Patients seeking retreatment were less motivated for treatment, and tooth irregularity was the chief reason for seeking treatment in both groups. Although an objective treatment need was not observed in the 2 groups, all of them had some occlusal traits that clinically justified the orthodontic treatment.

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.

Temporomandibular joint and normal occlusion: Is there anything singular about it? A computed tomographic evaluation.

INTRODUCTION: The purpose of this study was to investigate the condyle-fossa relationship, the position of the condyles in their respective mandibular fossae, and the dimensional and positional symmetries between the right and left condyles in a sample with normal occlusion. METHODS: Thirty subjects from 15 to 32 years of age with normal occlusion had computed tomography scans of their temporomandibular joints. The images obtained from the axial slices were evaluated for possible asymmetries in size and position between the condylar processes. The images obtained from the sagittal slices were used to assess the depth of the mandibular fossa, the condyle-fossa relationship, and the centralization of the condyles in their respective mandibular fossae. Paired Student t tests were applied, and Pearson product moment correlations were determined after measurements on both sides were obtained. RESULTS: The largest mediolateral diameter of the mandibular condylar processes (P = 0.022) and the posterior joint spaces (P = 0.048) showed statistically significant differences between the right and left sides. Statistically significant (P <0.05) anterior positioning of the condyles (noncentralized position) was observed. CONCLUSIONS: No singular characteristic in the temporomandibular joints of the normal occlusion group was verified. The largest mediolateral diameter of the mandibular condylar processes and the posterior joint spaces showed statistically significant differences between the right and left sides. Evaluation of the position of the condyles in their respective mandibular fossae showed noncentralized positioning for the right and left sides.

Multiple hyperdontia: Report of an unusual case.

Supernumerary teeth are an infrequent developmental anomaly that can appear in any area of the dental arch and can affect any dental organ. Multiple supernumerary teeth, or hyperdontia, is rare in people with no other associated diseases or syndromes. Conditions commonly associated with hyperdontia include cleft lip and palate, trichorhinophalangeal syndrome, cleidocranial dysplasia, and Gardner's syndrome. A black girl, aged 11 years 8 months, came for consultation; radiographs showed 81 teeth: 18 deciduous, 32 permanent, and 31 supernumerary. The main concern initially was to determine whether she was syndromic, and she was referred to a geneticist. G banding analysis showed pericentric inversion of chromosome 9; the chromosome formula was 46, XX, inv (9) (p13q21). Orthodontic treatment for this patient will be a clinical challenge because of the great number of teeth to be extracted and the alterations in the shapes of the teeth. Treatment goals should be established by a multidisciplinary team, where oral surgeon, orthodontist, periodontist, and prosthodontist come together to solve a medical and dental puzzle, eliminating the pieces that do not fit and searching for new ones to obtain an occlusion that will give the patient physiologic conditions of normality and esthetic satisfaction.