Root Resorption Of Incisors Research Articles

Cone-beam computed tomography-based diagnosis and treatment simulation for a patient with a protrusive profile and a gummy smile

For patients with bimaxillary protrusion, significant retraction and intrusion of the anterior teeth are sometimes essential to improve the facial profile. However, severe root resorption of the maxillary incisors occasionally occurs after treatment because of various factors. For instance, it has been reported that approximation or invasion of the incisive canal by the anterior tooth roots during retraction may cause apical root damage. Thus, determination of the position of the maxillary incisors is key for orthodontic diagnosis and treatment planning in such cases. Cone-beam computed tomography (CBCT) may be useful for simulating the post-treatment position of the maxillary incisors and surrounding structures in order to ensure safe teeth movement. Here, we present a case of Class II malocclusion with bimaxillary protrusion, wherein apical root damage due to treatment was minimized by pretreatment evaluation of the anatomical structures and simulation of the maxillary central incisor movement using CBCT. Considerable retraction and intrusion of the maxillary incisors, which resulted in a significant improvement in the facial profile and smile, were achieved without severe root resorption. Our findings suggest that CBCT-based diagnosis and treatment simulation may facilitate safe and dynamic orthodontic tooth movement, particularly in patients requiring maximum anterior tooth retraction.

Health of periodontal tissues and resorption status after orthodontic treatment of impacted maxillary canines.

The aim of the present study was to evaluate the changes of incisor root resorption associated with impacted maxillary canines and health of periodontal tissues around maxillary canines erupted with orthodontic treatment. Twenty patients with a unilateral palatally impacted maxillary canine were included in the study. Cone-beam computed tomography images taken before and after orthodontic treatment were compared with the contralateral canines serving as control teeth. Root resorption was present in 10% of central and 40% of lateral incisors before treatment. After treatment, the incidence of resorption decreased. The thickness of the buccal bone surrounding the impacted canines was similar to that surrounding the contralateral canines, except in the apical area. Periodontal pocket depth and alveolar bone loss were greater for the impacted canine teeth than for the contralateral canines. Incisor root resorption associated with impacted canine teeth showed signs of repair after orthodontic treatment. Slight differences related to periodontal health were found between the previously impacted teeth and contralateral canine teeth.

Evaluation of maxillary central incisors on the noncleft and cleft sides in patients with unilateral cleft lip and palate-Part 2: Relationship between root resorption, horizontal tooth movement, and quantity of grafted autogenous bone.

To evaluate the relationship between external apical root resorption (EARR) of the maxillary central incisors (U1), horizontal orthodontic tooth movement, and quantity of grafted bone in subjects with unilateral cleft lip and palate (UCLP) over an average duration of 8 years. Thirty subjects with UCLP were evaluated for EARR of U1 after edgewise treatment (T2). The teeth were classified as having no EARR, moderate EARR (combined into "no/moderate" EARR), or severe EARR. Frontal cephalometric radiographs acquired at eruption of U1 (T0), less than 6 months before secondary alveolar bone grafting (T1), and T2 were evaluated to determine the horizontal inclination (U1-axis angle) and distance of the root apex from the median line (U1-root-VL distance). On the cleft side, the quantities of grafted bone at less than 12 months postsecondary bone grafting and at T2 were evaluated using the alveolar bone graft (ABG) scale. Cleft-adjacent teeth exhibited more severe EARR than did teeth on the noncleft side. The cleft side exhibited greater changes in U1-axis angle and U1-root-VL distance between T0 and T2 than did the noncleft side. On the cleft side, the ABG score at T2 in the severe EARR group was significantly lower than that in the no/moderate EARR group. These measurements were correlated with EARR grade. Cleft-adjacent U1 exhibited more severe EARR than did the U1 on the noncleft side, which might be associated with orthodontic treatment-induced changes in horizontal inclination and root apex movement. On the cleft side, severity of EARR may be correlated with the success of ABG.

Root Resorption in Mandibular Incisors During Orthodontic Treatment with Invisalign®: A Radiometric Study

Background: Existing literature indicates that orthodontics patients are more likely to have severe apical root shortening, interesting mostly maxillary, followed by mandibular incisors. Objectives: The aim of the present study was to investigate the incidence and severity of root resorption (RR) in mandibular incisors of adult patients treated with aligners. Methods: The study group consisted of 71 adult healthy patients (mean age 32.8 ± 12.7) treated with aligners (Invisalign®, Align Technologies, San Jose, CA, USA) for the intrusion of the lower incisors. Root and crown lengths of a total of 279 lower incisors were measured in panoramic radiographs at the beginning (T0) and at the end (T1) of aligner therapy. Individual root-crown-ratio (RCR) of each tooth and therefore the relative changes of RCR (rRCR) were determined. Results: 44% of the 279 measured teeth presented a reduction of the pre-treatment root length. A reduction in percentage of > 0% up to 10% was found in 26.76% (n = 76), a distinct reduction of > 10% up to 20% in 12.32% (n = 35) of the sample. 4.58% (n = 13) of the teeth were affected by a clinically relevant reduction (> 20%). Conclusions: Orthodontic treatment with Invisalign® aligners could led to RR in cases in which intrusion of the lower incisors is planned. However, the incidence of RR is comparable to data described in case of application of light forces with fixed appliances, and considerably lower than what has been described for traditional comprehensive orthodontic treatments.

Severe root resorption of the upper central incisors as a consequence of playing the flute

This study presents a case of severe root resorption of the maxillary central incisors in an 18-year-old woman who was referred for orthodontic treatment of irregular dental arches. A detailed history revealed that she used to play the block flute on an everyday basis during childhood. Against all warnings, she continued to firmly press her teeth into the mouthpiece of the instrument. Impressions of the upper central incisors were clearly visible on the instrument. Although it is well known that excessive occlusal forces can result in root resorption, to the authors' knowledge,this case involves one of the first reported occurrences of extensive root resorption that was most likely caused by playing a wind instrument during childhood.

Apical Resorption of Upper Incisors and Canines During Orthodontic Treatment in Class III Orthognathic Surgery Patients – a Longitudinal Cone Beam Computer Tomography Study

Summary Introduction. Although severe root resorption is rare, it is a side effect of orthodontic treatment which affects tooth prognosis. Patients with severe dentofacial deformity, for whom orthodontic treatment and orthognathic surgery was done at the age of 18 and later, had long duration orthodontic treatment and orthognathic surgery, and are at a high risk of root resorption. The impact of orthognathic surgery on root resorption has not been sufficiently studied, and therefore is an interesting topic to research. Aim of the Study. To identify the risk factors for apical root resorption of maxillary incisors and canines as a result of orthodontic and surgical treatment of Class III malocclusion involving LeFort I osteotomy. Material and methods. The root lengths of upper incisors and canines were measured on cone beam computer tomography (CBCT) scans obtained from a database of orthognathic surgery patients. As a criteria for root resorption was chosen the difference in root lengths between different time points. The measurements were performed using the scans taken before orthodontic treatment (T1), before surgery (T2), and after post surgery orthodontic treatment (T3), of 28 subjects, aged 20.5 ± 3.81 years, with the mean presurgery treatment time of 19.9 ± 8.8 months, and post-surgery time of 7.1 ± 3.1 months. Changes in root lengths during different time spans were correlated with treatment duration, the initial crown/root ratio, and the severity of dentofacial deformity (Wits appraisal, ANB angle, and overjet). Results. During T1 - T2 the roots of the lateral incisors shortened by a maximum of 0.78 ± 0.83 mm (p < 0.001), at a rate of 0.04 mm per month. During T2 - T3 the lengths of the central incisor roots decreased most by 0.49 ± 0.52 (p < 0.001) at a rate of 0.07 mm per month. The resorption speed for canines increased from 0.03 mm to 0.1 mm per month before and after surgery. There were statistically significant correlations between the crown-root ratio and the incisor root length (r = 0.319 for lateral and r = 303 for central, both p<0,05) and for canines (r = 482, p<0.01). The associations between the shortened root length, in different time spans for different teeth, and the severity of malocclusion were inconsistent. Conclusions. Overall, the shortened root length during combined orthodontic and surgical treatment might not be clinically significant. After surgery, the rate of root resorption (mm per month) increased, especially for canines. The teeth with initially shorter roots showed more resorption during treatment.

Effects of impacted maxillary canines on root resorption of lateral incisors : A cone beam computed tomography study.

The aim of this study was to analyze the amount of root resorption of maxillary lateral incisors by relating the position, location, and angulation of the impacted canine using cone-beam computed tomography (CBCT). The study sample consisted of panoramic and CBCT radiographs of 46 patients with a unilateral impacted canine (16 males and 30 females; mean age: 19.53±6.66 and 19.44±5.77years, respectively). Sector location and canine angulation were measured in panoramics. All tomographs were obtained using CBCT (NewTom 5G, QR, Verona, Italy) and three-dimensional (3D) reconstructions of the maxillary laterals assessed by Mimics 14.01 image analysis software. Upper lateral incisor volume was smaller on the impacted side (401.95±83.69mm3) than on the nonimpacted side (433.54±92.6mm3, P<0.05). There were no significant differences of lateral root resorption volume when comparing the impacted canines being on the labial or palatal sides (P>0.05), but impacted canine angulation was significantly steeper on the labial side (70.85°) than on the palatal side (46.09°, P<0.05). The volume of root resorption of laterals when comparing the various positions of the canine in different sectors or canine angulation in 30o intervals was not statistically significantly different (P>0.05). The impacted canines caused root resorption oflateral incisors. The angulation of the canine was steeper on the labial side thanon the palatal side but root resorption of adjacent laterals was not different. There were no statistically significant differences in the amount of root resorption of the laterals when the canine was evaluated according to localization and angulation.

Root resorption of maxillary incisors retracted with and without skeletal anchorage.

Our objective was to compare root resorption degree of the maxillary central incisors retracted with and without skeletal anchorage. This nonrandomized historical control study included 37 patients requiring maximum anterior retraction and treated with extraction of 2 maxillary premolars. Group 1 consisted of 22 patients (11 male, 11 female) in whom anterior retraction was performed without skeletal anchorage, and group 2 included 15 patients (3 male, 12 female) treated with skeletally anchored anterior retraction. Periapical radiographs were used to evaluate root resorption degree by a scoring system. The groups were compared regarding the resorption score and resorption degree distribution with the Mann-Whitney U test, chi-square test, and Z test on proportions. There was no statistically significant intergroup difference regarding root resorption, but the number of patients with severe and extreme root resorption degrees was significantly greater in group2. Although the root resorption degree of the skeletal anchorage group was not significantly different from the group without skeletal anchorage, the number of patients with severe to extreme resorption in the first group was significantly greater. Therefore, careful clinical monitoring of skeletally anchored anterior retraction is needed, especially when there are known root resorption predisposing factors.

Cone-Beam Computed Tomography Evaluation of the Positions of Unerupted Maxillary Canines with Incisor Root Resorption

Purpose: To establish a new coordinate system using the incisive canal and incisive foramen in cases confirmed to have root resorption in the maxillary incisor region by cone beam computed tomography (CBCT) to investigate the positions of the central and lateral incisor roots and erupting maxillary canine tooth crowns in the horizontal plane. Methods: Nine patients (two males; mean age: 10.5 years old) with suspected incisor root resorption due to erupting maxillary canines on panoramic X-ray images and in whom incisor root resorption was confirmed on CBCT images were evaluated. A control group of 12 patients with a supernumerary tooth on one side (three males; mean age: 8.6 years old) was also examined. X, Y, and Z-axes were defined, and the positions of the centers of the central incisor root (U1) and lateral incisor root (U2) and the canine cusp (U3) were examined, along with alveolar process width and length. Results: In the control group, U1, U2, and U3 were located within a certain range without overlap, while, in the incisor root resorption group, U3 overlapped with U1 and U2 and tended to deviate centrally. U2 tended to be located further posteriorly than U3. The anteroposterior diameter of the alveolar process was 1.2 mm shorter in the incisor root resorption group (p < 0.05). Conclusions: The risk of incisor root resorption accompanying canine eruption can be evaluated early by investigating the canine position on a horizontal plane established on the upper anterior tooth dentition CT images with a coordinate system using the incisive canal and incisive foramen.

The relationships between the arrangement of teeth, root resorption, and dental maturity in bovine mandibular incisors.

ObjectiveThe objective of this study is to investigate the eruption pattern and root resorption of the bovine anterior dentition in relation to growth-related parameters based on dental maturity.MethodsA cross-sectional study was conducted on 110 bovine anterior mandibles by using standard radiography, cone-beam computed tomography (CBCT), and actual measurements. We determined the relationships between the stages of dental maturity by using a modification of Demirjian's method and various growth-related parameters, such as the activity of the root-resorbing tissue and mobility of the deciduous teeth. The correlation of growth-related parameters with interdental spacing and distal unusual root resorption (DRR) of the deciduous fourth incisor was assessed. The cause of mesial unusual root resorption (MRR) of the deciduous fourth incisor was determined on the basis of the arrangement of the permanent third incisor.ResultsAn independent t-test and chi-square test indicated significant differences in growth-related parameters associated with dental arch length discrepancy and factors related to the shedding of deciduous teeth between the low and high dental maturity groups. The samples with interdental spacing and DRR showed a larger sum of mesiodistal permanent crown widths and higher dental maturity than did the respective controls. Samples with MRR tended to show a lingually rotated distal tip of the adjacent tooth crown.ConclusionsDental maturity has relevance to the interdental spaces and unusual root resorption of mixed dentition. The position of the adjacent tooth crown on CBCT may be correlated with the occurrence of unusual root resorption of the incisor.

The Orthodontic Treatment of a Patient with Idiopathic Root Resorption in Upper Incisors

The Orthodontic Treatment of a Patient with Idiopathic Root Resorption in Upper Incisors

Evaluation of position of maxillary impacted canine and its effect on adjacent teeth - A correlation study between panoramic radiography and cone beam computed tomography

Aims and Objective: The present study was undertaken to evaluate the usefulness of panoramic radiograph in determining labiopalatal position of MIPC and its effect on permanent teeth by assessing the mesiodistal position of MIPC on panoramic radiograph and by correlating it with 3D position on CBCT. Methods: The designed study was a cross-sectional study enrolling total 60 patients of either sex with 76 impacted maxillary canines. Patients were divided into 2 groups based on age criteria i.e age groups: ?15 years and >15 years. Evaluation of MIPC in both groups was done by digital panoramic radiograph and subjects were subjected to CBCT imaging for exact localization of MIPC and detection of root resorption of permanent incisors. The sector location on panoramic radiographs was compared with the labiopalatal position of impacted maxillary canines on CBCT. The statistical correlation between panoramic and CBCT findings was examined using the Pearsons Chi-square test. Results: Most of the positions of MIPC were labial (35%), followed by palatal (34%) and mid-alveolus (30%). Labial MIPC on CBCT were more frequent in sectors 1, 2 and 3 and palatal MIPC were more frequent in sector 4 and 5 on panoramic radiographs. Distribution of mid-alveolus canines showed great variation with most of them located in sector 1 and 5. Root resorption of permanent incisors (28.94%) was observed in sectors 3, 4 and 5. Conclusions: The present study recommended that labiopalatal position of MIPC and resorption of permanent incisors might be predicted using sector location on panoramic radiography.

Maxillary incisor root resorption induced by ectopic canines part 2: clinical management

There is extensive material in the orthodontic literature regarding canine ectopia but far less on the possible sequelae of ectopic canines, such as the resorption of maxillary incisor roots. This is the second paper in a two-part series exploring the subject of ectopic canines inducing root resorption of maxillary incisors. The first paper examined the orthodontic and dental literature in order to compile a review of the prevalence rates and longevity outcomes of maxillary incisor root resorption as a result of impacted maxillary canines. This second paper will explore the clinical management of patients with maxillary incisor resorption as a result of an impacted maxillary canine. Clinical Relevance: Maxillary incisor root resorption induced by ectopic maxillary canines is an issue for all dental specialties; however, the awareness of each stage of management is limited. This paper aims to increase awareness and provide a reference point for appropriate management by clinicians.

Root resorption following periodontally accelerated osteogenic orthodontics

Background Literature evidence suggests that root resorption, an adverse side effect of orthodontic therapy, may be decreased under conditions of alveolar osteopenia, a condition characterized by diminished bone density and created secondary to alveolar corticotomy (Cort) surgery. Purpose To compare root resorption of the maxillary central incisors following nonextraction orthodontic therapy with and without Cort surgery. Materials and Methods The sample comprised two groups, with and without Cort and was matched by age and gender: Cort-facilitated nonextraction orthodontics with 27 subjects, 53 central incisors of mean age 24.8 ± 10.2 years, and conventional (Conv) nonextraction orthodontics with 27 subjects, 54 incisors with mean age of 19.6 ± 8.8 years. All periapical radiographs were taken with the paralleling technique; total tooth lengths of the right and left central incisors were measured by projecting and enlarging the periapical radiographs exactly 8 times. Results t-tests revealed a significant decrease in treatment time in the Cort group (6.3 ± 8.0 vs. 17.4 ± 20.2 months,P = 0.000). Pretreatment root lengths were not significantly different (P = 0.11), but Conv had significantly shorter roots at posttreatment when compared with Cort (P = 0.03). Significant root resorption (P &lt; 0.01) occurred in both Cort (0.3 mm) and Conv (0.7 mm), but the increment of change was significantly greater in Conv (P &lt; 0.03). The variable SNA increased significantly in the Cort (P = 0.001) group and decreased significantly in the Conv group (P &lt; 0.001). Conclusions Based on the conditions of this study, it may be concluded that Cort-facilitated nonextraction orthodontic therapy results in less root resorption and enhanced alveolar support within a significantly reduced clinical service delivery time frame. Rapid orthodontic treatment and reduced apical root resorption are probably due to the transient osteopenia induced by the Cort surgery and inspired by regional acceleratory phenomenon.

Orthodontic Treatment of Maxillary Incisors with Severe Root Resorption Caused by Bilateral Canine Impaction in a Class II Division 1 Patient.

This case report shows the successful alignment of bilateral impacted maxillary canines. A 12-year-old male with the chief complaint of the protrusion of his maxillary anterior teeth happened to have bilateral maxillary canine impaction on the labial side of his maxillary incisors. Four maxillary incisors showed severe root resorption because of the impacted canines. The patient was diagnosed as skeletal Class II malocclusion with proclined maxillary incisors. The impacted canine was carefully retracted using sectional buccal arch wires to avoid further root resorption of the maxillary incisors. To distalize the maxillary dentition, two palatal miniscrews were used. After 25 months of treatment, the maxillary canines were well aligned without any additional root resorption of the maxillary incisors.

Maxillary incisor root resorption induced by ectopic canines part 1: prevalence rates and longevity outcomes

Root resorption of maxillary incisors as a result of impacted maxillary canines is a sequelae of canine ectopia that has been reported in the literature in terms of case reports and retrospective case series. However, to our knowledge there has been no work done that consolidates the available information on the subject, particularly since the advent of improved imaging techniques with higher rates of detection of maxillary incisor root resorption. This paper aims to review the prevalence rates of maxillary incisor root resorption induced by impacted maxillary canines, as well as to discuss the diagnosis and prognosis of teeth affected by this phenomenon. Clinical Relevance: Maxillary incisor root resorption induced by ectopic maxillary canines is an issue which may be encountered by all dental specialties; however, the awareness of each stage of management is frequently unknown by clinicians. This paper aims to increase awareness and provide a reference point for appropriate management.

A posteriori registration and subtraction of periapical radiographs for the evaluation of external apical root resorption after orthodontic treatment.

PurposeThis study employed a posteriori registration and subtraction of radiographic images to quantify the apical root resorption in maxillary permanent central incisors after orthodontic treatment, and assessed whether the external apical root resorption (EARR) was related to a range of parameters involved in the treatment.Materials and MethodsA sample of 79 patients (mean age, 13.5±2.2 years) with no history of trauma or endodontic treatment of the maxillary permanent central incisors was selected. Periapical radiographs taken before and after orthodontic treatment were digitized and imported to the Regeemy software. Based on an analysis of the posttreatment radiographs, the length of the incisors was measured using Image J software. The mean EARR was described in pixels and relative root resorption (%). The patient's age and gender, tooth extraction, use of elastics, and treatment duration were evaluated to identify possible correlations with EARR.ResultsThe mean EARR observed was 15.44±12.1 pixels (5.1% resorption). No differences in the mean EARR were observed according to patient characteristics (gender, age) or treatment parameters (use of elastics, treatment duration). The only parameter that influenced the mean EARR of a patient was the need for tooth extraction.ConclusionA posteriori registration and subtraction of periapical radiographs was a suitable method to quantify EARR after orthodontic treatment, and the need for tooth extraction increased the extent of root resorption after orthodontic treatment.

Root resorptions related to ectopic and normal eruption of maxillary canine teeth – A 3D study

Objective. To assess the incidence and severity of root resorption of maxillary incisors caused by ectopically and normally erupting maxillary canines and to analyse factors influencing root resorption of incisors using cone beam computed tomography. Subjects and methods. The study sample comprised 59 patients with a total of 80 canines. Forty-six of the canines, in 37 patients, were defined as ectopic and 34 canines, in 22 patients, were defined as normal. The severity of root resorptions were analysed according to studies by Ericson and Kurol. Multiple logistics regression was used to evaluate the association between various factors and root resorptions. Results. The prevalence of root resorptions was significantly higher in the ectopic canine group, 11.0% of the central incisors and 67.6% of the lateral incisors in comparison to 0% and 36.2% in the normal erupting group. Most resorptions were defined as ‘slight’ and were located in the middle third of the root. There was a statistically significant relationship between canines located mesial to the midline of the lateral incisor and root resorption on the maxillary incisors. Conclusion. The present results show that root resorption of maxillary lateral incisors was common in patients referred to CBCT imaging due to maxillary canine eruption disturbances. Although significantly more frequent in patients with ectopically erupting canines, lateral incisor resorption was also found in association with approximately every third of the normally erupting canines. The best predictor for root resorption seemed to be location of the canine mesial in relation to the midline of the lateral incisor root.

Incisal Apical Root Resorption Evaluation after Low-Friction Orthodontic Treatment Using Two-Dimensional Radiographic Imaging and Trigonometric Correction.

Root resorption shall be taken into consideration during every orthodontic treatment, and it can be effected by the use of different techniques, such as the application of low friction mechanics. However, its routinely assessment on orthopantomography has limitations related to distortions and changes in dental inclination. The aim of this investigation was to evaluate the severity of apical root resorption of maxillary and mandibular incisors after low-friction orthodontic treatment, using the combination of panoramic and lateral radiographs, and applying a trigonometric correction. A hospital based Retrospective study at the orthodontic Department (Dental School, University of Brescia, Spedali Civili di Brescia, Brescia, Italy). Ninety-three subjects (53 females and 40 males; mean age, 14 years) with mild teeth crowding were treated without extractions by the same operator using a low-friction fixed appliance following an integrated straight wire (ISW) protocol. The pre- and post-treatment tooth lengths of the maxillary and mandibular incisors were measured on panoramic radiographs. A trigonometric factor of correction for the pre-treatment length was calculated based on the difference between the pre and post-treatment incisal inclination on lateral cephalograms. The changes in lengths were investigated using the Student's t-test for paired values (p<0.05). Maxillary central incisors showed no changes (0.3%, 0.6%), maxillary lateral incisors showed a small increase (1.4%, 1.8%) that was attributed to the completion of root development in younger patients, mandibular central and lateral incisors underwent slight resorption (-3.1%, -3.4%). A statistically significant difference was found for the mandibular incisors but not for the maxillary ones. In patients with mild crowding and consequent low amount of root movement, a low-friction orthodontic treatment can lead to slight apical root resorption, mainly involving lower incisors. The use of a trigonometric correction in the panoramic radiograph analysis may reduce the limitations of this 2D evaluation.

Predisposing factors for severe incisor root resorption associated with impacted maxillary canines

Severe incisor root resorption (SIRR) associated with impacted maxillary canines is rare but has important implications. Early diagnosis and treatment are imperative. In this investigation, we aimed to identify predisposing factors for impacted canine-linked SIRR. Clinical and radiographic data of 55 consecutive patients (77 canines) with SIRR of 96 incisors were compared with data from 57 consecutive control subjects (72 canines). The studied variables were age, sex, position of the impacted canine, size of the dental follicle, and incidence of anomalous lateral incisors. Lateral incisors were more often affected than central incisors, and bilateral SIRR was common. When each variable was examined separately, SIRR was significantly associated with female sex, severely mesiodistally displaced and vertically positioned canines in the middle third of the adjacent incisor root, dental follicles wider than 2 mm, and normal lateral incisors. The multivariate statistical analysis showed that the risk for SIRR was significantly higher in female subjects (4.2 times) with enlarged dental follicles (8.3 times) and normal lateral incisors (5.8 times). SIRR should be carefully screened in female patients with enlarged dental follicles and normal lateral incisors. A greater degree of canine displacement might also be associated with SIRR.