Evaluation of stress and displacement of maxillary canine during the single canine retraction in the maxillary first premolar extraction cases- A finite element study

OBJECTIVES

This finite element study aimed to simulate maxillary canine movement during anterior teeth retraction.

MATERIALS AND METHODS

Three methods of maxillary canine movement including miniscrew sliding with high hooks (MSH), miniscrew sliding with low hooks (MSL), and the traditional sliding method (TS) without using miniscrews were simulated using three-dimensional finite element analysis. The initial displacement of the maxillary canine, the maximum principal stress of the periodontal ligament and the Von Mises stress were calculated.

RESULTS

The distolingual tipping movements of the canine were shown in three movement modes. MSH showed a small tendency to lingual tipping movement and a extrusion movement while MSL had the largest lingual inclination. TS demonstrated a tendency toward distolingual torsion displacement. Compressive stress values were mainly concentrated in the range - 0.003 to -0.006 MPa. For tensile stress, the distribution of MSH and MSL was concentrated in the range 0.005 to 0.009 MPa, TS was mainly distributed about 0.003 MPa. Von Mises equivalent stress distribution showed no significant difference.

CONCLUSIONS

The loss of tooth torque was inevitable, irrespective of which method was used to close the extraction space. However, miniscrew application and higher hooks reduced the loss of torque and avoided lingual rotation.

CLINICAL RELEVANCE

This study shows that miniscrew implants with different hooks can better control the movement of the maxillary canines. The non-invasive nature of the finite element analysis and its good simulation of dental stress and instantaneous motion trend have a clinical advantage in the analysis of tooth movement.

Sex estimation by volumetric evaluation of the maxillary canine using cone-beam computed tomographic images

BACKGROUND

Teeth can be a reasonable part of sex estimation in case of being the single evidence available or in doubt although they are not as accurate as bones in sex estimation. The size of teeth is greater in males than in females. In this study, it was aimed to determine cut-off values of the tooth volume (TV) and root volume (RV) of the maxillary canines and to evaluate the validity of the method for discriminating between males and females.

METHODS

Cone beam computed tomography (CBCT) images of 250 individuals aged 18 to 63 years with equal age and sex distribution were assessed retrospectively. The sample divided into reference set including 168 images of 84 females and 84 males and validation set including 82 images of 48 females and 34 males. Receiver operating characteristic (ROC) curve analysis, and Youden's index were used to determine cut-off values of the volumetric measurements and to test the discriminative performance of the method.

RESULTS

The optimal cut-off values of TV ≥ 581 mm3 and RV ≥ 334 mm3 for estimating sex were established from the reference set. The sensitivity (Se), specificity (Sp), and accuracy (Ac) were 0.77 for TV ≥ 581 mm3 while they were 0.82, 0.77, and 0.79 for RV ≥ 334 mm3. When we tested the previously derived cut-off values of TV of the maxillary canine, the Se, Sp, and Ac were found to be respectively 0.71, 0.90, and 0.82 for TV ≥ 619 mm3 and 0.97, 0.27, and 0.56 for TV ≥ 510 / 460 mm3 (right/left).

CONCLUSIONS

The identified cut-off values of TV and RV of the maxillary canines can be used to estimate sex with moderate accuracy when the only evidence available is teeth or in case of doubt. The method's applicability should be assessed for different populations.

Evaluation of skeletal and dentoalveolar dimensions in patients with maxillary unilateral impacted canine: a cone beam computed tomographic study

OBJECTIVE

To assess the skeletal and dentoalveolar dimensions of subjects with the unilateral maxillary-impacted canine and compare it with the non-impacted side using cone beam computed tomography (CBCT).

METHODS

A split-mouth study that included 26 CBCTs (52 sides) with unilateral impacted canine was designed. The parameters analyzed were alveolar height; bucco palatal width at 2 mm, 6 mm, and 10 mm from alveolar crest; premolar width; lateral angulation of incisors; root length of lateral incisors; and crown-root angulation of lateral incisors. Obtained data were statistically analyzed by unpaired independent t-test.

RESULTS

The bucco palatal width at 2 mm and the premolar width from mid-palatal raphe were 1.22 mm and 1.71 mm less on the impacted side, respectively; the central and lateral incisor angulations were less by 3.69 degrees and 3.40 degrees, respectively, on the impacted side; the lateral incisor root length was 2.8 mm shorter on the impacted side; the crown-root angulation for lateral incisor was 2.4 degrees more on the impacted side.

CONCLUSION

The following conclusions can be drawn: (1) The premolar width is less on the impacted side. (2) The incisors are more distally angulated on the impacted side. (3) The crown-root angulation of the lateral incisor is mesially directed on the impacted side.

CLINICAL RELEVANCE

Asymmetric arch expansions should be undertaken in severe transverse asymmetries. In the beginning stages of treatment, the arch alignment, excluding incisors, must be undertaken to safeguard the roots of incisors.

Association between maxillary canine impaction and other dental anomalies: radiological study of a mixed dentition children's cohort from an orthodontic clinic

PURPOSE

To investigate the significance of association between maxillary impacted canines and various dental anomalies.

METHODS

Files of 874 orthodontic patients were evaluated for the presence of maxillary impacted canines. From this sample, a group of 97 patients (39 males and 58 females) with at least 1 impacted maxillary canine consisted the study group. This group was compared to a control group of 97 patients (42 males and 55 females) that was created by random selection from the initial sample without maxillary canine impaction. The impaction diagnosis was made from the panoramic radiographs. Chi-square test was used to perform the analysis for significant associations. Stepwise discriminant analysis, binary logistic regression and classification tree were used to identify best combinations.

RESULTS

Statistically significant difference was found for peg-shaped maxillary lateral incisors and infraoccluded deciduous molars. The presence of peg-shaped upper lateral incisors arises the probability of impacted canine to 83.3%, a distal displaced unerupted second premolar to 63.16% and the impaction of any other teeth to 80% as showed by the classification tree.

CONCLUSIONS

The presence of peg-shaped maxillary lateral incisors and infraocclusion of deciduous molars can be considered major valuable early risk indicators for maxillary canine impaction, because they manifest before the maxillary canine eruption. Special consideration should be given on distal displaced unerupted second premolar and the impaction of any other teeth. Patients with these dental anomalies are candidates for future interceptive treatment for canine eruption.

Evaluation of maxillary sinus dimensions and volume using cone beam computed tomography in patients with unilaterally displaced palatal and buccal maxillary canines

OBJECTIVES

To evaluate and compare the maxillary sinus (MS) dimensions and volume in unilaterally displaced palatal and buccal maxillary canines.

METHODS

CBCT images for 133 patients were included in the study. Maxillary canines were unilaterally displaced palatally in 83 patients (PDCs) and buccally in 50 patients(BDCs). The following variables were measured: canine position in relation to MS walls, MS pneumatization and MS dimensions and volume.

RESULTS

MS was extended to the incisor region in 10% and 13% and to the canine region in 48% and 23% in BDCs and PDCs subjects, respectively. In BDC subjects, maxillary canine crown tip was more laterally (24.23 mm compared to 22.93 mm (p < 0.05)) and closer vertically (5.82 mm compared to 9.58 mm (p < 0.001)) to the MS, maxillary canine root tip was closer to the MS anterior (0 mm compared to 1.64 mm (p < 0.05)) and lateral (19.70 mm compared to 22.02 mm (p < 0.001)) walls and the MS volume (11.57mm³ compared to 9.09 mm³ (p < 0.001)) was increased in the displaced side compared to the non-displaced side. In PDC subjects, a significant difference between the displaced and non-displaced sides was detected in the vertical (3.28 mm compared to 5.89 mm (p < 0.001)) and lateral (21.63 mm compared to 24.25 mm (p < 0.001)) position of maxillary canine to the MS wall, the anterior (- 0.84 mm compared to 1.13 mm (p < 0.05)) and lateral (20.48 mm compared to 22.44 mm (p < 0.001)) position of canine root tip to the MS and the MS volume (7.71mm³ compared to 9.14mm³ (p < 0.001)). PDC sides differed from BDC sides in the lateral and vertical position of canine crown tip to MS and in MS volume. PDC showed negative association with MS volume and anteroposterior skeletal relationship and a positive association with MS height.

CONCLUSIONS

PDCs subjects have a reduced MS volume and BDCs subjects have an increased MS volume. PDCs are associated with reduced MS volume, increased MS height and Class III skeletal relationship.

Performance of deep learning technology for evaluation of positioning quality in periapical radiography of the maxillary canine

Objectives

The aim of the present study was to create and test an automatic system for assessing the technical quality of positioning in periapical radiography of the maxillary canines using deep learning classification and segmentation techniques.

Methods

We created and tested two deep learning systems using 500 periapical radiographs (250 each of good- and bad-quality images). We assigned 350, 70, and 80 images as the training, validation, and test datasets, respectively. The learning model of system 1 was created with only the classification process, whereas system 2 consisted of both the segmentation and classification models. In each model, 500 epochs of training were performed using AlexNet and U-net for classification and segmentation, respectively. The segmentation results were evaluated by the intersection over union method, with values of 0.6 or more considered as success. The classification results were compared between the two systems.

Results

The segmentation performance of system 2 was recall, precision, and F measure of 0.937, 0.961, and 0.949, respectively. System 2 showed better classification performance values than those obtained by system 1. The area under the receiver operating characteristic curve values differed significantly between system 1 (0.649) and system 2 (0.927).

Conclusions

The deep learning systems we created appeared to have potential benefits in evaluation of the technical positioning quality of periapical radiographs through the use of segmentation and classification functions.

Different Management Approaches in Impacted Maxillary Canines: An Overview on Current Trends and Literature

AIM

This study aimed to overview and collect the current trends and techniques in managing maxillary impacted canines by retrieving recent literature, in a chronological manner from the prevention to the very late stages of treatment in adults.

BACKGROUND

We performed a review on the recent literature regarding the current trends on the management of impacted canines. We have researched various types of available articles such as clinical trials and case presentations, meta- and systematic analyses, and literature reviews focusing on clinical management of impacted canines and their outcome evaluations. We adhered to those articles published within the last decade with a focus on treatment planning for impacted and displaced canines.

REVIEW RESULTS

Depending on the diagnosis and its timing of it, a maxillary impacted canine can be managed by either prevention or interception, surgical opening followed by autonomous eruption or orthodontically traction, autotransplantation, and at last by removal and space closure. These techniques are elaborated one by one according to the age and severity of the diagnosis.

CONCLUSION

Impaction of the canines is a manageable abnormality which is highly dependent on the timing and localization of the displaced tooth. Early detection will give the upper hand to orthodontists to engage by either prevention through extraction of deciduous canines or intercepting via assistant devices to create more space. According to the clinical situation, open or closed surgical uncovering might be required to bond an attachment. However, generally, those techniques did not show any significant clinical distinction in the outcome assessments.

CLINICAL SIGNIFICANCE

These approaches are highly technique sensitive and require collaborations with other specialties. Proper diagnosis and prognosis assessment are necessary before making any decision to bring an impacted canine in alignment.

Orthopantomographic analysis of the intraosseus position of the maxillary canines

The aim of this work was to analyse the intraosseous position of the maxillary canine in orthodontic patients. It was an exploratory pilot study prior to the next research work to develop a predictive model based on a regression analysis initially including a large number of variables. 105 subjects from 6 to 12 years from both genders were included in this study. Four variables were used. The study showed that there was no marked gender dimorphism concerning the intrabony position of the canine; the latter is quite similar on both sides, and the older the age, the smaller the angulation of the canine. The values obtained for the angulation of the canine, its depth of impaction, its position in relation to the lateral incisor and the premolars, correspond to an average impaction severity and treatment difficulties.

Impacted maxillary canine in unilateral cleft lip and palate: A literature review

Background

The incidence of canine impaction in unilateral cleft lip and palate (UCLP) is increasing and in most cases is a part of a syndrome. The provision of different treatment modalities in these patients is a challenging and daunting task.

Objective

The objective of the present review was to scrutinize the available evidence on canine impaction in UCLP patients.

Materials and methods

Using PRISMA guidelines, a review was conducted via the PubMed (MEDLINE), ISI Web of Knowledge, Google Scholar, and Embase databases using different keywords. Studies were shortlisted and inspected according to the following inclusion criteria: (1) papers published in English over the past 40 years, (2) study participants with maxillary canine impaction in unilateral cleft lip and palate, (3) studies reporting on canine impaction and cleft lip and palate, and (4) no age limit was applied so studies published on both children and adults with unilateral cleft lip and palate and canine impaction were included. Studies which justified inclusion criteria were included whereas the rest of the studies were removed.

Results

A total of 279 studies were retrieved using the search strategy. After removing duplicate reports and scrutinizing those based on title and abstract, 54 studies were shortlisted for full text review. Following the review, 22 studies were included in the final list. The presentation of data was based on the year of study, type of cleft, gender, age of bone graft, spontaneous eruption, and surgical exposure.

Conclusion

Every UCLP patient is different and treatment modalities should vary according to the characteristics, subjective response, and variability of the malformation.