Maxillary Incisor Root Research Articles

Diagnostic Approaches of Palatogingival Groove: A Systematic Review

Palatogingival Grooves (PGG) constitute developmental anatomical irregularities primarily situated along the palatal aspects of the roots of maxillary incisors. Literature is sparse on diagnostic approaches of PGG. Our study aimed to alleviate clinicians the process of recognizing anomaly. Systematic electronic searches of scientific literature without publication date or language restriction were undertaken in 2023.11.03 research was conducted in PubMed, Willey Online Library, Science Direct and Medline Ovid. Using specific keywords 54 articles with 67 cases were included in our study according to inclusion and exclusion criteria. Pre-made Cochrane data extraction templates were used for frequency evaluation, nonparametric Spearman’s, Kendall rank correlation coefficients, Mann-Whitney U Test and Odds ratio was assessed by statistic to evaluate significant correlations. Most quantitively expressed symptoms of PGG included increased tooth mobility, appearance of purulent discharge, sinus tract and periodontal pocket with an average mean of 9,14 ± 2,30 mm along with painful vertical per-cussion. However, statistical assessment showed inverse correlation between in-creased mobility and painful percussion. Furthermore, quantitively, deeper perio-dontal pockets were accompanied by more prominent gingival alterations, however only one opposing significant correlation was noted between the depth of per-iodontal pocket and existence of additional root. Frequency evaluation revealed that IPR was the main diagnostic tool used in majority of cases. Deeper periodontal pocket was assessed by conjunction of two or three tools. CBCT was used most with deeper periodontal pocket averaging 9,75 ± 1,02 mm. In conclusion, quantita-tive data suggest that periodontal pockets averaging 9,14 ± 2,30 mm, I or II-degree mobility, painful percussion and purulent discharge are the main PGG characteristics, with sparce significant correlations between them. IPR was noted as the main roentgenological modality as should be used firstly when suspecting PGG, yet both quantitative and statistical data suggest that CBCT is ought to be used to alleviate the assessment.

Quantitative statistical evaluation of maxillary and mandibular incisor root canal morphology in Saudi patients

Abstract Introduction: Clinical practice demands understanding the complexity of the root canal system to achieve desired treatment goals. The statistically detailed morphology of the tooth and root canal morphology is very important to know. Therefore, the present study aims to investigate the statistical analysis of root canal morphology and morphological variations of maxillary and mandibular incisor teeth using cone-beam computed tomography (CBCT) in Saudi patients attending King Saud University Dental Hospital. Materials and Methods: CBCT images of 480 patients were selected. Number of roots and root canal configuration were identified and categorized according to Vertucci’s classification. Tooth length, distance from cementoenamel junction (CEJ) to the area of canal division, and width of the canal at the area of division were also evaluated. Bilateral symmetry and association between gender and age with the different variables were investigated. Data were analyzed using Chi-square, multiple linear regression, and McNemar’s tests. Results: A total of 3412 teeth were evaluated. All maxillary teeth had one root with Type I canal configuration. For mandibular teeth, all exhibited one root with the majority having Type I canal configuration in central (71.2%) and lateral (75%) incisor teeth. There was a statistically significant association between number of canals and age in mandibular incisor teeth observed only in females (P < 0.001), while no association was observed between canal configuration and gender (P = 0.900 and P = 0.721, respectively). Multiple regression analyses showed that age and gender significantly explain the difference of the variance in tooth length (P < 0.001). Moreover, bilateral symmetry was observed in 98.1% of mandibular central and 97.6% of lateral incisor teeth with no statistically significant association (P = 1 and P = 0.058, respectively). Conclusion: All maxillary and most mandibular incisor teeth present with one root and Type I canal configuration. In general, males have longer teeth than females, with a significant decrease in length with each year increase in age. Mandibular lateral incisor teeth exhibited the highest mean distance from CEJ to point of canal separation and highest mean width in the area of canal division.

Impacted maxillary canine: Assessment of prevalence, severity and location of root resorption on maxillary incisors: A retrospective CBCT study

The maxillary permanent canine is one of the most frequently impacted teeth, which often requires multidisciplinary management. A common complication of canine impaction is root resorption of the adjacent dentition. The aim of this retrospective study was to report the prevalence of root resorption of maxillary incisors adjacent to impacted maxillary canines from small volume CBCT images by trained clinicians. A secondary objective was to report the location and severity of root resorption. CBCT images of patients with impacted maxillary canines (unilateral and bilateral) who attended a joint orthodontic/surgical multidisciplinary clinic were screened. Descriptive statistics were used to investigate associations of patient characteristics and presence of root resorption. Generalized estimating equations (GEE) logistic regression model were used to identify predictors of root resorption. In all, 148 impacted maxillary canines (122 patients) were analysed. The majority of patients were under 18 years of age (71.6%) with impacted canines present in more females (68.2%) than males (31.8%). Maxillary lateral incisors showed the highest prevalence of root resorption (38.5%). The apical region was the most common location of resorption for lateral incisors (20.9%) with a variable degree of severity evident: slight (10.1%), moderate (15.6%), and severe (12.8%). Although no significant predictors of root resorption were identified, a weak association was evident for age and root development. In this cohort of patients, the roots of maxillary lateral incisors are most likely to suffer from root resorption in the presence of an impacted maxillary canine. Clinicians should consider the extent, location and severity of resorption of adjacent teeth when planning treatment decisions and mechanics in cases of impacted maxillary canines.

Complications of Surgically Assisted Rapid Maxillary/Palatal Expansion (SARME/SARPE)-A Retrospective Analysis of 185 Cases Treated at a Single Center.

Objectives: The study aims to assess and classify complications in patients treated for maxillary transverse deficiency using surgically assisted rapid maxillary/palatal expansion (SARME/SARPE) under general anesthesia. The classification of the complications aimed to assess the difficulty of their treatment as well as estimate its real cost. Methods: The retrospective study covered 185 patients who underwent surgery for a skeletal deformity in the form of maxillary constriction or in which maxillary constriction was one of its components treated by a team of maxillofacial surgeons at one center (97 females and 88 males, aged 15 to 47 years, mean age 26.1 years). Complications were divided into two groups: early complications (up to 3 weeks after surgery) and late complications (>3 weeks after surgery). In relation to the occurrence of complications, we analyzed the demographic characteristics of the group, type of skeletal deformity (class I, II, III), presence of open bite and asymmetry, surgical technique, type and size of appliance used for maxillary expansion, as well as the duration of surgery. Results: In the study group, complications were found in 18 patients (9.73%). Early complications were found in nine patients, while late complications were also found in nine patients. Early complications include no possibility of distraction, palatal mucosa necrosis, perforation of the maxillary alveolar process caused by the distractor and asymmetric distraction. Late complications include maxillary incisor root resorption, no bone formation in the distraction gap, and maxillary incisor necrosis. None of the patients required prolonged hospitalization and only one required reoperation. Conclusions: Complications were found in 18 patients (9.73%). All challenges were classified as minor difficulties since they did not suppress the final outcome of the treatment of skeletal malocclusion. However, the complications that did occur required additional corrective measures. Surgically assisted rapid maxillary expansion, when performed properly and in correlation with the correct orthodontic treatment protocol, is an effective and predictable technique for treating maxillary constriction.

Invasión radicular del conducto incisivo durante el tratamiento de ortodoncia debido a un torque radicular palatino excesivo. Reporte de un caso

Aim: Patients presenting with bimaxillary proclinati-on often have an accompanying maxillary alveolar pro-cumbency. Case Report: Posterior relocation of the anterior alveolus is an important mechanism to reduce this prominence. Torquing the maxillary incisor roots palatally allows the anterior alveolus (point A) to remodel distally. This technique is non-invasive and therefore has good patient acceptance. Results: The following case report demonstrates the involvement of the incisive canal due to increased palatal root torque of the maxillary left central incisor root Conclusions: The use of 3D imaging in the diagnosis, its clinical complications as well as their remedial measures is also discussed. Keywords: Incisive canal; Root resorption; Torque; Orthodontics; Maxilla; Cone-beam computed tomography.

Çocuklarda Maksiller Anterior Dişlerin Kökleri ile Komşuluğundaki Anatomik Yapılar Arasındaki İlişkinin Değerlendirilmesi: Konik Işınlı Bilgisayarlı Tomografi Çalışması

ABSTRACT
 Background: In our study, we aimed to evaluate the distances between the roots of maxillary incisors and the nasopalatine canal and the floor of the nasal cavity, and the buccal cortical bone thickness at the apices of the roots of these teeth by Cone Beam Computed Tomography (CBCT) in children in the permanent dentition period.
 Materials and Methods: CBCT images of 49 patients aged 6-14 years were evaluated. In the sagittal plane, the distances of the apices of the maxillary central teeth with the nasopalatine canal and with the floor of the nasal cavity were evaluated. Buccal cortical bone thickness at the apex of the roots of maxillary anterior teeth was examined. These data were compared in terms of gender and whether the teeth had open or closed apices.
 Results: When the mean distance of the maxillary central teeth (11,21) to the nasopalatine canal was evaluated in terms of the open/closed apex status of the teeth and gender, there was no significant relationship (p>0.05). Among the maxillary anterior teeth (11, 21,12, 22), the root apex of tooth 22 was the farthest from the floor of the nasal cavity and the root apex of tooth 12 was the closest. It was found that the mean buccal cortical bone thickness of maxillary anterior teeth 11 and 21 with open apex was significantly higher than those with closed apex (p

OUTCOME EVALUATION OF ENDODONTIC TREATMENT WITH PROTAPER ROTARY INSTRUMENT SYSTEM ON MAXILLARY INCISORS

In recent years, thanks to the rapid advancement of science and technology and a better understanding of the anatomy of the root canal system, many new endodontic instruments and materials have been introduced with the desire to minimize complications in the process of preparing the root canal, help the cleaning and shaping process to complete well. It is noteworthy that the emergence of new endodontic files made of Nickel-Titanium alloy (NiTi files), which, according to the recommendations of manufacturers, make the preparation of root canals faster and more efficient, with a much simpler shaping technique than previous stainless-steel files. This is the topic that attracts great interest from clinicians. Therefore, it is necessary to conduct studies to evaluate these types of instruments. Over the years, there has been a lot of research on NiTi instrument systems carried out in the world, which mainly focused on the current types of rotary NiTi files. In Vietnam, although the NiTi instrument system appears a lot on the market and is increasingly employed by many dentists and endodontic experts, the amount of research on them is limited.
 Therefore, in order to contribute to more understanding and improve the effectiveness of endodontic treatment with niti rotary instrument systems we carry out the research: “Outcome Evaluation of endodontic treatment with Protaper rotary instrument system on maxillary incisors" with two aims:
 
 To evaluate root canal sealing results with cone beam computed tomography (CBCT)
 To evaluate the outcomes of maxillary incisor root canal treatment with the Protaper rotary instrument system.

Evaluation of alveolar bone morphology of incisors with different sagittal skeletal facial types by cone beam computed tomography: A retrospective study

BackgroundSafe orthodontic tooth movement should be performed within the alveolar bone. The purpose of this study was to evaluate the morphology of the alveolar bone of incisors. Materials and methodsThis retrospective study included pretreatment cone beam computed tomography of 120 patients with malocclusion. Patients were divided into 4 groups (Class I, Class II division 1, Class II division 2 and Class III) according to the subspinale-nasion-supramental (ANB) angle and occlusal relationship. The sagittal root positions, anterior and posterior root-cortical bone angles (AR-CA and PR-CA), root-crown ratios (RCR) and alveolar bone thickness were evaluated. ResultsThe sagittal root positions were mainly positioned against the labial cortical plate in the maxillary incisors of the Class II division 2 group and engaged by both the labial and palatal cortical plates in the mandibular incisors of the Class III group. The AR-CA was lower than that in the other groups (P < 0.01) in the maxillary incisors of the Class II division 2 group, and the AR-CA and PR-CA were lower than those in the other groups (P < 0.01) in the mandibular incisors of the Class III group. The alveolar thickness showed no significant difference between the Class II division 1 group and the Class I group (P > 0.05), the middle and lower anterior alveolar thickness (LAAT and MAAT) were lower than those in other groups (P < 0.01) in the maxillary incisors of the Class II division 2 group, and the alveolar thickness at the measurement sites of the middle and lower line were lower than those in other groups (P < 0.01) in the mandibular incisors of the Class III group. The RCR had a moderate positive correlation with the LAAT. ConclusionBased on several limitations, this study found that maxillary incisor roots were at risk of penetrating the alveolar bone of Class II division 2 patients, and mandibular incisors may have a relatively small range of safe movement on both the labial and lingual sides of Class III patients during orthodontic treatment.

Maxillary Incisor Root Canal Diameter Assessments Using Cone-Beam Computed Tomography Imaging

Maxillary Incisor Root Canal Diameter Assessments Using Cone-Beam Computed Tomography Imaging

Three-dimensional analysis of root changes after orthodontic treatment for patients at different stages of root development

We investigated changes in the roots of maxillary incisors at different stages of root development after fixed-appliance treatment using cone-beam computed tomography. Data from 52 subjects receiving fixed-appliance treatment were collected retrospectively. The subjects were divided into 3 groups: mixed dentition group (aged 7-10 years; root development stage: Nolla eighth-10th; n= 16), early permanent dentition group (aged 12-18 years; root development stage: Nolla 10th; n= 20), and adult group (aged 18-35 years; root development stage: Nolla 10th; n= 16). Changes in root lengths and volume of the maxillary central incisors were measured using pretreatment and posttreatment cone-beam computed tomography. The root lengths and volumes of maxillary central incisors in the mixed dentition group significantly increased after orthodontic treatment (P>0.05). No significant differences were found when comparing the final root length and volume of the mixed dentition group with the pretreatment maxillary incisor values of the early permanent dentition group (P>0.05). The early permanent dentition group showed a significant decrease in root length (P<0.05), and both the root length and volume of the adult group significantly decreased after treatment (P<0.05). The differences in root length and volume reduction between the 2 groups were not significant (P>0.05). Orthodontic treatment had no significant negative impact on the continued root development of incomplete roots with two-thirds root formation. Both the early permanent dentition and adult groups exhibited root resorption after orthodontic treatment. It seemed age was not a factor that resulted in significant root resorption during routine orthodontic leveling and alignment treatment once the roots were fully developed.

Oral Cleft Related-Genes may be Involved in Root Curvature of Maxillary Lateral Incisors.

The maxilla is formed by the medial nasal and maxillary processes fusion. The dental lamina develops from 2 origins connecting in the lateral incisor. The maxillary lateral incisor region is often affected by dental anomalies and clefting. It is possible that genes involved in oral cleft could also be associated with a variety of phenotypic variations in the maxillary lateral incisor. In this phenotype–genotype study, we explored the association between polymorphisms in the oral-cleft-related genes BMP2 and BMP4 and root curvature of maxillary lateral incisors. Cross-sectional study. Universities and private clinics. Panoramic radiographs and DNA from 231 patients were analyzed. Schneider method (1971) was applied to estimate the degree of root curvature of the maxillary lateral incisors and to classify the root as straight (5° or less) or curved (higher than 5°). Genetic polymorphisms in BMP2 (rs235768 and rs1005464) and BMP4 (rs17563) were genotyped. Statistical analysis was performed. A total of 401 teeth (199 left and 202 right) were evaluated. Genetic analysis demonstrated trends toward association for the rs1005464 in BMP2 ( P = .025) in co-dominant model and in dominant model ( P = .026) for left incisors. The rs235768 in BMP2 showed trends toward association with the degree of root curvature in left incisors in the recessive model ( P = .031). rs17563 in BMP4 also showed trends toward association with the degree of the root curvature in left incisors ( P = .019). BMP2 (rs235768 and rs1005464) and BMP4 (rs17563) might be involved in maxillary lateral incisor root curvature.

Volumetric Evaluation of Maxillary Lateral Incisor Root Resorption due to Positional Variations of Impacted Canine.

Introduction The purpose of this study was to investigate the relationship of the volume of lateral incisor resorption and impacted canine features. Materials and Methods This study consisted of CBCT images of 47 samples with unilateral impacted maxillary canine (13 males and 34 females). The volume of lateral incisors in impacted side and nonimpacted side was calculated with the Mimics 10.01 software. Canine and lateral incisor angulations were measured in panoramic reformatted images. The canine cusp tip distance from midpalatal suture was measured in axial cross-section images. Results The difference between two sides volume was considered as the mean volume of resorption (MVR) that was statistically significant (P < 0.001). MVR was not statistically significant between two sexes (P=0.95), in buccopalatal and mesiodistal positions of impacted canine, and in different angulations or distances of the impacted canine to midline (P > 0.05). The concurrent effect of the canine distance to the midline and the angle of the canine with the lateral incisor on the MVR were statistically significant (P=0.049). Conclusion The maximum rate of lateral root resorption is when the distance from the canine to the midline is less than 5 mm and the angle of the canine to the lateral incisor is 30–60 degrees.

Morphological Evaluation of Impacted Maxillary Canine and Adjacent Teeth Using Three-Dimensional Reconstructed CBCT Images: An Analytical Cross-Sectional Study

Introduction: The structural characteristics of unilaterally impacted maxillary canines and adjacent teeth were compared to the nonimpacted side. Three-dimensional (3D) cone-beam computed tomography (CBCT) was used to analyze and evaluate the various parameters. The aim of this study was a quantitative comparison of teeth adjacent to buccally and palatally impacted maxillary canines. Methods: CBCT records of 40 patients with unilateral impacted maxillary canine were allocated to this study. The morphological characteristics of teeth on the impaction and non-impaction sides of the same patient were examined. 3D reconstructed CBCT images were assessed using the OnDemand 3D program. Results: The dependent samples t test was used for data analysis with a level of statistical significance of 0.05. There was a significant increase in the size of the maxillary canine crown and a decrease in the maxillary lateral incisor root dimensions on the impacted side. No significant difference was observed in the morphology of the maxillary first premolar on either side. Conclusion: The impacted canine showed greater size compared to the eruption side. The decrease in root dimensions of the lateral incisor on the impacted side may indicate the possibility of root resorption.

Morphologic changes of the incisive canal and its proximity to maxillary incisor roots after anterior tooth movement

The objectives were to evaluate the morphologic changes of the incisive canal (IC) and the influence of IC proximity to apical root resorption of maxillary central incisors after anterior tooth movement. Pretreatment and posttreatment cone-beam computed tomography images of adults (aged 18-47years) were retrospectively evaluated. Subjects were divided into control group with minimal incisor movement (n=32; maxillary incisor tip movement<2mm) and maximum retraction group (n=35; maxillary incisor tip movement>4mm). The shape, direction, morphologic changes of the IC, the proximity of the central incisor root to IC, and the amount of apical root resorption associated with the proximity after orthodontic treatment were compared. Changes in the shape of the IC were not observed in both control and retraction groups. However, 11.4% (4 of 35 subjects) in the retraction group indicated changes in the direction of the IC from slanted-straight to slanted-curved type after the direction of anterior retraction. The thickness of the cortical bone surrounding the IC and the distance between the incisor root and IC significantly decreased after orthodontic treatment in both groups (P<0.05). However, these changes were significantly greater in the retraction group than in control (P<0.0001). Contact or invasion of the incisor root to the IC was more prominent in the retraction group (42.8%-54.3%) than the control (10.9%-12.5%) (P<0.0001). The amount of root resorption indicated a tendency to increase in the order of separation, approximation, contact, and invasion in relation to IC. Although remodeling of IC was evident in some patients, contact or invasion of the maxillary central incisor roots to IC was fairly high after maximum anterior retraction.

3D Analysis of maxillary incisor root inclinations in cases of unilateral maxillary canine impaction.

To evaluate the association between maxillary incisor root inclinations and unilateral canine impaction. A retrospective cross-sectional study of 59 pre-treatment CBCT scans (23 palatal impactions, 10 buccal impactions, and 26 comparison patients). Using Dolphin 3-D Imaging software (Chatsworth, CA), relative incisor angulations to a 3D palatal plane and the shortest distance between the canine crown and the root of the closest lateral incisor were calculated. A one-way analysis of variance was used to determine whether there were any differences between the three independent groups of impactions concerning the four continuous dependent variables incisor root inclination for each maxillary incisor. Patients with unilaterally impacted maxillary canines demonstrate significant differences in the root inclination position on the ipsilateral (0.0001 &gt; P = 0.002) but not contralateral side. While palatal impactions (PIC) are associated with buccally positioned roots of the ipsilateral lateral (-9.05 degrees) and central incisors (-7.91 degrees), buccal impactions (BIC) are only associated with palatally positioned roots of the ipsilateral lateral incisors (+10.40 degrees) alone. A more labial position of the lateral incisor root was correlated with a more proximally located, coronally positioned, and medially displaced adjacent PIC (0.013 &gt; P &lt; 0.026). This is a retrospective cross-sectional convenience sample. Patients with impacted maxillary canines, whether PIC or BIC, do not show generalized retroclination or proclination of all four maxillary incisor roots. Instead, changes in incisor root inclination were only ipsilateral to the impacted canine. BIC is only associated with palatal displacement of the ipsilateral lateral incisor root, whereas PIC is associated with labial root displacement of both ipsilateral incisors.

Incisor position and alveolar bone thickness.

To evaluate incisor position and its relationship to alveolar bone in untreated optimal occlusions and in untreated Class II malocclusions. Fifty-seven lateral cephalograms of individuals with naturally occurring optimal occlusions (mean age = 23 years) were used to assess positions of central incisors and their relationships to alveolar bone. Data were compared to a sample of 57 individuals with untreated Class II malocclusions with concurrent anterior-posterior (AP) skeletal discrepancies (mean age = 16.9 years). Significant intergroup differences were found for AP jaw relationship, maxillary alveolar bone thickness, mandibular incisor inclination, maxillary incisor root distance to labial surface of alveolar bone, and mandibular incisor root apex distance to labial surface of alveolar bone. Small differences between females and males existed for several variables. In both samples, maxillary incisor roots were located closer to the labial surface of alveolar process than to the palatal surface by roughly a 2:1 ratio. Mandibular incisor root apices were generally equidistant from the labial and lingual surfaces of the alveolus in the optimal sample but closer to the lingual surface in the Class II sample. Maxillary incisors tend to occupy the anterior one-third of the alveolus in untreated individuals, regardless of AP interarch dental relationships or AP jaw relationships. Mandibular incisor root apices tend to be centered within the alveolus in untreated optimal occlusions but are more positively inclined, and their root apices are more posterior in untreated Class II malocclusions.

Cone beam computed tomography (CBCT) assessment of incisor root resorption (IRR) associated with impacted maxillary canines (IMC). Literature review

CBCT assessment of impacted canine improves canine localization to adjacent teeth and provides higher level of confidence in the treatment plan compared to 2D images. However, there is conflicting evidence to support using CBCT as a routine first-line imaging method in patients with impacted maxillary canine and incisor root resorption. Consequently, there are doubts regarding difference in diagnostic and treatment planning between the use of conventional 2D and CBCT sets. Therefore, the present review will attempt to summarize the new aspects regarding the benefits of three-dimensional (3D) diagnostic techniques (cone-beam computed tomography, CBCT), including the accuracy of localization of impacted canine and the detection of the degree and location of root resorption of maxillary incisors.

Relationship of Angulation of Maxillary Impacted Canines with Maxillary Lateral Incisor Root Resorption

Objective: To assess the relationship of ɑ and s angles of maxillary impacted canines with maxillary lateral incisor root resorption . Material and Methods: For this, 40 patients (between 11 and 45 years) with impacted maxillary canines presenting to a private orthodontic clinic were evaluated.20% of the cases were male and 80% were female. The ɑ and s angles were measured on panoramic radiographs to determine the angulation of impacted canine. CBCT scans had been taken by ProMax 3D CBCT system were used to examine lateral root reorption. The relationship between the size of ɑ and s angles of impacted maxillary canines and root resorption in the adjacent maxillary lateral incisor was analyzed using SPSS version 22. Results: The mean size of ɑ and s angles had no significant correlation with the presence/absence, location, or severity of root resorption in the adjacent lateral incisor or the buccolingual position of impacted canine. The ɑ and s angles in impacted maxillary canines cannot be used to determine the incidence or severity of root resorption in the adjacent lateral incisor . Conclusion: No significant association between ɑ and s angles and incidence or severity of root resorption in the adjacent lateral incisor was found.

Risk factors for maxillary impacted canine–linked severe lateral incisor root resorption: A cone-beam computed tomography study

Impacted maxillary canine-linked severe lateral incisor root resorption (SIRRc) is rare, but it greatly influences the survival of the affected teeth. Our study was designed to investigate the risk factors for SIRRc. Eighty-two patients with SIRRc and 81 patients with impacted maxillary canines but without SIRRc were included and evaluated by cone-beam computed tomography in software programs by 1 examiner (H.W.). Age, sex, positions, and dental follicles and angular inclinations of impacted canines were measured in this study. Binary logistic regression was used to analyze the risk factors for SIRRc. SIRRc was highly related to sex, vertical and mesiodistal position, dental follicles sizes of canines, and intersection angles in 3dimensions.The regression analysis showed female sex, dental follicles between 1mm and 3mm, mesial third and apical third position, vertical angle smaller than 30°, and the relative angle between 30° and 60° were significant risk factors for SIRRc. Early diagnosis and treatment for SIRRc are imperative, especially in Asian patients that are female with apically and mesially positioned canines as well as wider dental follicles. Vertical angles and relative angles of impacted canines should also be noticed.

Controlling incisor torque with completely customized lingual appliances.

PurposeTo test the null hypothesis of no significant deviation between the center of rotation (CROT) and the center of resistance (CRES) during space closure in Angle class II division 2 subjects achieved using a completely customized lingual appliance (CCLA) in combination with class II elastics and elastic chains.MethodsThis retrospective study included 29 patients (male/female 11/18; mean age 15.6 [13–27] years) with inclusion criteria of an Angle class II/2 occlusion of least of half of a cusp, maxillary dental arch spacing, completed CCLA treatment (WIN, DW Lingual Systems, Bad Essen, Germany) in one center with a standardized archwire sequence and use of class II elastics and elastic chains only. Maxillary incisor root inclination was assessed by X‑ray superimpositions of the maxilla at the beginning (T1) and the end (T3) of CCLA treatment. Using Keynote software (Apple®, Cupertino, CA, USA), the incisor’s CROT was assessed with the point of intersection of the incisor axes (T1; T3) following vertical correction of overbite changes. CRES was defined at 36% of the incisor’s apex–incisal edge distance.ResultsThe null hypothesis was rejected: the mean CROT − CRES difference was 52.6% (p < 0.001). The mean CROT was located at 88.6% (min–max 51–100%) of the incisor’s apex–incisal edge distance. Although 6.9% of CROT were located between the CRES and the alveolar crest, the vast majority (93.1%) were assessed between the alveolar crest and the incisal edge, or beyond.ConclusionCCLAs can create upper incisor palatal root torque even in cases in which lingually oriented forces applied incisally to the center of resistance of the upper incisors counteract these intended root movements.