Factors related to root resorption in edgewise practice

Assessment of mandibular retromolar space in adults with regard to third molar eruption status

OBJECTIVE

The aim of this study was to compare the difference in length and width of the mandibular retromolar space (RMS) stratified by the different eruption and impaction statuses of the third molars in patients with skeletal Class I malocclusion.

MATERIALS AND METHODS

The right mandibular RMS in 186 adult patients categorized according to the different statuses of the third molar was analyzed by using cone-beam computed tomography (CBCT). The shortest distances between the inner lingual cortex of the mandibular body and second molar root were measured parallel to the posterior occlusal line (POL) at depths of 2, 4, 6, 8, and 10 mm (mandibular retromolar space length in root level, RL_in2,4,6,8,10) on the axial slices with the cementoenamel junction (CEJ) as the reference level. The width of the RMS and second molar root was measured vertical to the POL at the terminal point of the molar distalization at depths of 2, 4, 6, 8, and 10 mm (width of the mandibular retromolar space, BW_2,4,6,8,10/ width of the second molar distal root, TW_2,4,6,8,10) from the CEJ.

RESULTS

RL in different measurement planes was 2.72 ± 2.22 ~ 3.74 ± 2.26 for Group A, 5.27 ± 1.68 ~ 9.10 ± 2.04 for Group B, 1.94 ± 2.34 ~ 5.71 ± 4.37 for Group C, 1.83 ± 2.95 ~ 5.05 ± 4.24 for Group D, and 5.93 ± 3.97 ~ 10.52 ± 2.16 for Group E. The BW measurement results for A ~ E group were 9.71 ± 1.41 ~ 10.51 ± 1.81, 9.83 ± 1.39 ~ 12.55 ± 2.11, 9.96 ± 1.21 ~ 12.17 ± 1.62, 9.82 ± 1.47 ~ 12.28 ± 2.77, and 10.02 ± 1.20 ~ 12.75 ± 0.82, respectively. There was no significant difference between men and women in any measurements (P > 0.05). Patients with normal third molars erupted and those vertically impacted possessed larger RMS lengths than those in which the third molars were missing, horizontally impacted or mesially impacted (P < 0.05). In each measurement plane, TW was significantly smaller than BW (P < 0.05).

CONCLUSIONS

Sex had no effect on the length or width of the mandibular RMS. Different statuses of third molars can also differentially affect the mandibular RMS. The mandibular RMS width is not a limit for mandibular molar distalization.

CLINICAL RELEVANCE

When considering the distalization of mandibular molars, more attention should be directed to the lingual cortex of the mandible, and CBCT scans are recommended for patients who require significant mandibular molar distalization. The mandible buccal shelf and retromolar area maybe a safe zone to insert the miniscrew for molar distalization.

Comparison of surface roughness of root cementum and orthodontically induced root resorption craters from high- and low-fluoridation areas: a 3D confocal microscopy study

Background

Fluoride has a major role in strengthening the structure of enamel against acids. Despite differences between caries and root resorption processes, both events inherently involve acidic dissolution of dental tissues. The aim of the present study was to investigate the effects of water fluoridation levels on the surface roughness of root cementum and resorption craters. The findings provided more insight into the influence of fluoride on the surfaces of intact cementum surface and resorption craters.

Methods

Twenty-eight orthodontic patients were recruited from two cities in Turkey, with high (≥ 2 ppm) and low (≤ 0.05 ppm) water fluoridation. These patients needed bilateral maxillary first premolar extraction as part of their orthodontic treatment and were allocated into two study groups (n = 14 in each group) based on water fluoridation exposure level: the high-fluoride group (HF) and low-fluoride group (LF). 150 g of buccal tipping forces was applied to all maxillary first premolar teeth for 12 weeks with a beta-titanium spring which was reactivated every 4 weeks. All maxillary premolars were removed at the end of the experiment for surface roughness assessment using three-dimensional confocal microscopy and the associated software. The buccal root surface and the largest buccal resorption crater were investigated.

Results

Resorption craters were significantly rougher in LF group compared to HF group (p = 0.002). Craters were rougher than the intact root surfaces (p = 0.000). Cervical and apical regions were significantly rougher than the middle region (p = 0.000 and p = 0.024, respectively).

Conclusions

Higher water fluoridation level of ≥ 2 ppm resulted in significantly smoother root resorption craters than low water fluoridation level of ≤ 0.05 ppm when the teeth were subjected to 150 g of buccal tipping force. Fluoride seems to have a protective role at the interface of root resorption, and further mineral or histological studies may shed light on the exact protective process against root resorption.

The Shape of Nasopalatine Canal as a Determining Factor in Therapeutic Approach for Orthodontic Teeth Movement-A CBCT Study

The aim of this study was to evaluate the impact of the nasopalatine canal (NPC) shape and its morphometric characteristics on expected teeth movement by assessing the distance to maxillary central incisors (MCIs) according to NPC type. The retrospective study was performed on 133 CBCT images. The following parameters were obtained: the antero-posterior diameter (A-P) of the nasal foramen (NF), canal length, A-P and mediolateral diameter (M-L) of the incisive foramen (IF), and the distance between NPC and MCIs. With the exception of being hourglass-shaped, each NPC shape showed specific impacts of NPC shape on the relationship between NPC diameters at different sections and distances to MCIs. In banana-shaped NPC, a significant correlation was observed for A-P NF diameter, while in cylindrical-shaped NPC, a significant correlation was observed for NPC length. The increase in M-L IF, A-P IF, A-P NF, and NPC length in funnel-shaped NPC may be a risk factor for interventions that could result in teeth movement. According to the results, it seems that the proposed methodological approach for analysis of CBCT slices in the anterior maxilla may offer detailed information that could be an additional tool in planning the procedures that result in expected teeth movement.

Surgical-orthodontic retreatment of a severe skeletal Class III malocclusion following an orthodontic camouflage

Introduction:

Class III malocclusions are some of the most difficult occlusal anomalies to be treated. Some patients with this condition may require orthognathic surgery, while others may be treated with dental camouflage. Proper patient assessment and selection remains critical in order to achieve favorable results.

Objectives:

This report outlines the case of an 18-year-old male who sought retreatment for a severe skeletal Class III dentofacial deformity after undergoing orthodontic camouflage treatment involving mandibular arch extractions. A treatment plan comprising dental decompensation and orthognathic surgery was implemented in order to achieve optimal facial and occlusal results.

Results:

After 28 months of treatment, skeletal and dental correction was achieved and facial features were significantly improved. The orthognathic surgery required a 20-mm sagittal maxillomandibular skeletal correction, combined with a 4-mm correction of the midlines and a 2-mm impaction of the maxilla.

Conclusion:

Dental compensation may be a risky treatment alternative for severe dentoskeletal discrepancies. In these patients, orthodontics combined with orthognathic surgery is the recommended treatment option.

Morphological changes of the anterior alveolar bone due to retraction of anterior teeth: a retrospective study

Backgroud

To analyze the morphological changes of the anterior alveolar bone after the retraction of incisors in premolar extraction cases and the relationship between incisor retraction and remodeling of the alveolar base represented by points A and B displacements.

Methods

Pre- (T0) and post-treatment (T1) lateral cephalograms of 308 subjects in the maxilla and 154 subjects in the mandible who underwent the orthodontic treatment with extraction of 2 premolars in upper or lower arches were included. Alveolar bone width and height in both the maxillary and mandible incisor area were measured at T0 and T1 respectively. By superimposing the T0 and T1 cephalometric tracings, changes of points A and B, and the movement of the incisors were also measured. Then the correlation between incisor movement and the displacements of points A and B was analyzed.

Results

The alveolar bone width (ABW) showed a significant decrease in both maxilla and mandible (P < 0.001) except the labial side of the mandible (P > 0.05). The alveolar bone height (ABH) showed a significant increase in the labial side of maxilla and a significant decrease in the lingual side of maxilla and mandible. A strong positive correlation was verified between incisor movement and position changes of points A and B in both horizontal and vertical directions.

Conclusions

Anterior alveolar bone width and height generally decreased after orthodontic treatment. Incisor retraction led to significant position changes of points A and B. The decrease of anterior alveolar bone due to significant incisor retraction should be taken into account in treatment planning.

Impact of piezocision-assisted orthodontics on root resorption and alveolar bone: a prospective observational study

OBJECTIVES

To assess the impact of orthodontic treatment combined with piezocision (OT-PC) on root structure and alveolar bone.

MATERIALS AND METHODS

Twelve adults were treated with OT-PC. Pre- and post-treatment CBCT examinations evaluated apical root resorption (ARR) and alveolar bone height and thickness changes. Pre- and post-treatment differences were compared using one-sample t test and Wilcoxon signed-rank test.

RESULTS

ARRs were generalized and significantly more severe in both anterior sextants compared with posterior sextants. Bone thickness decreased significantly in the maxilla at mid-root and apex areas. The majority of mandibular alveolar bone dehiscences occurred on the buccal aspect at the mid-root level, especially where thickness was less than 0.3 mm. Overall bone height decreased twice as much on the buccal aspect (1.43 mm, P < 0.001) compared with the lingual aspect (0.67 mm, P = 0.001), most significantly in the lower incisors, where the average median loss was 2.10 mm (P = 0.003).

CONCLUSION

OT-PC causes minor negative effects on both alveolar bone and root resorption.

CLINICAL RELEVANCE

Orthodontic treatment combined with piezocision causes minor negative effects on periodontal support. Nevertheless, mild bone height loss on the buccal aspect of the mandibular teeth and root resorption in both anterior sextants have been detected with this new treatment.

Stainless steel and NiTi torque archwires and apical root resorption

Objective

The amount of apical root resorption when using the torque-segmented archwire (TSA) was investigated as well as the extent and direction of the therapeutically indicated apical movement and the treatment duration.

Materials and methods

The degree of apical root resorption in 18 randomly chosen Class II and Class I patients treated with the TSA, as well as in 18 conventionally treated patients were evaluated using pre- and posttreatment panoramic radiographs. The sagittal and vertical apical movements and inclination changes were determined based on pre- and posttreatment lateral cephalograms. Nonparametric tests were applied to test between treatment groups and steps. The Mann–Whitney U test, Kruskal–Wallis, Pearson correlation and Wilcoxon signed-rank test were applied for statistical analysis (p < 0.05).

Results

The incidence of root resorptions was 89–94.4% in low or moderate level. The relative root–crown ratio (rRCR) was not statistically different between the TSA and control groups except tooth 12. The axis of the incisors in the TSA group was significantly improved. The main direction of movement of the apices of the central incisors was retrusion and extrusion. No interdependence between the amount of resorption and the parameters of treatment duration, extent and direction of apical movement were found.

Conclusion

The results of the study showed that the amount of apical root resorption with the TSA is slight to moderate and can be compared to conventional orthodontic treatment. The TSA is hence a suitable method for applying targeted torques to the incisors.

A novel method for alveolar bone grafting assessment in cleft lip and palate patients: cone-beam computed tomography evaluation

Objectives

This retrospective cross-sectional study aimed to present a new method for secondary alveolar bone grafting (SABG) assessment and to qualitatively evaluate the SABG results in unilateral cleft lip and palate patients.

Materials and methods

Research was conducted according to the STROBE guidelines. The study group consisted of 21 patients with a mean age of 16 years. High-resolution cone-beam computed tomography (CBCT) was performed at least 1 year after grafting. The experimental side was the cleft side, and the contralateral side without a congenital cleft was the control. Measurements were performed at four levels of the maxillary central incisors’ roots according to the new scale with scores from 0 to 3. The sum of the scores provided a general assessment of bone architecture. The Wilcoxon signed-rank test was used for intergroup comparisons, and a Kappa coefficient was used for reproducibility measurements.

Results

High individual variability was found, and the bone architecture was significantly worse on the cleft side than on the noncleft side. The results showed 28.57% failure, 33.33% poor, 19.05% moderate, and 19.05% good results from the surgical procedure. Kappa coefficients produced results from 0.92 to 1.00 for intra-rater and from 0.81 to 1.00 for inter-rater reproducibility.

Conclusions

CBCT provides detailed information about alveolar bone morphology. The new assessment method is useful at every treatment stage and provides excellent repeatability. SABG did not provide good bone morphology, in most cases.

Clinical relevance

This research presents a new universal alternative for the assessment of SABG by utilizing CBCT.

Electronic supplementary material

The online version of this article (10.1007/s00784-020-03505-z) contains supplementary material, which is available to authorized users.

Prevalence and severity of apical root resorption during orthodontic treatment with clear aligners and fixed appliances: a cone beam computed tomography study

Background

Fixed appliances have been the mainstream for orthodontic treatment, while clear aligners, such as Invisalign system, have become increasingly popular. The prevalence of apical root resorption (ARR) in patients with clear aligners is still controversial. The aim of this study was to investigate and compare the prevalence and severity of ARR in patients treated with clear aligners and fixed appliances using cone beam computed tomography (CBCT).

Materials and methods

A total of 373 roots from 70 subjects, with similar baseline characteristics and the ABO discrepancy index scores (i.e., treatment difficulty), were included into two groups: the clear aligners group (Invisalign, Align Technology, California, USA) and fixed appliances group (Victory Series; 3 M Unitek, California, USA). Root length of each anterior tooth was measured on the CBCT images by two blinded investigators. The ARR on each tooth was calculated as the difference of root length before and after orthodontic treatment. Chi-square test and paired t test was used to compare the ARR between the two groups as well as before and after orthodontic treatments.

Results

Prevalence of ARR in the clear aligners group (56.30%) was significantly lower than that in the fixed appliances group (82.11%) (P < 0.001). The severity of ARR in the clear aligners group (0.13 ± 0.47 mm) was significantly less than that in the fixed appliances group (1.12 ± 1.34 mm) (P < 0.001). The most severe ARR was found on the maxillary canine (1.53 ± 1.92 mm) and lateral incisor (1.31 ± 1.33 mm) in the fixed appliances group; the least ARR was found on the mandibular canine (− 0.06 ± 0.47 mm) and lateral incisor (0.04 ± 0.48 mm) in the clear aligners group (P < 0.001).

Conclusions

The prevalence and severity of ARR measured on CBCT in patients with clear aligners were less than those in patients with fixed appliances.

Effects Of Triptolide On Tooth Movement And Root Resorption In Rats

Purpose

The aim of this study was to investigate the effects of triptolide on the tooth movement and root resorption in rats during orthodontic treatment.

Material and methods

A total of 48 male Wistar rats were divided into three groups of 16 each. The right maxillary first molars of rats were drawn mesially by closed coil nickel-titanium spring with a force of 50 g. The two experimental groups received intraperitoneal injections of triptolide for 14 days at a dose of 15 µg/kg/day and 30 µg/kg/day, respectively. The control group received vehicle injections. After 14 days, the rats were humanely killed. The amount of tooth movement was measured. Eight rats from each group were randomly chosen for analysis of the percentage of root resorption area by scanning electron microscopy. For the remaining eight rats in each group, the H&E staining, tartrate-resistant acid phosphatase (TRAP) staining and immunohistochemistry analysis were performed.

Results

The amount of tooth movement and the ratio of root resorption area were significantly decreased in the triptolide-treated rats. The number of TRAP-positive cells was significantly lower in triptolide-treated groups. Moreover, the expression of nuclear factor kappa B ligand (RANKL) was reduced. In contrast, the expression of osteoprotegerin was significantly up-regulated. In the tension side, the expressions of runt-related transcription factor 2 and osteocalcin were significantly enhanced by triptolide injection.

Conclusion

Triptolide injection could arrest orthodontic tooth movement and reduce root resorption in rats via inhibition of osteoclastogenesis. In addition, triptolide may exert a positive effect on osteoblastogenesis.

Relationship between periodontal status of mandibular incisors and selected cephalometric parameters : Preliminary results

Purpose

The aim of this cross-sectional study was to evaluate the correlation between the periodontal tissue of mandibular incisors and several dentoalveolar and skeletal cephalometric parameters.

Materials and methods

The sample consisted of 35 patients (mean age 26.42 ± 8.02 years). Eligibility criteria included good overall health status with no history of dental trauma, congenital defects, active periodontal diseases, restorative and prosthetic treatment in the area of the mandibular incisors. Gingival recession width and height (GRW, GRH), gingival thickness (GT), width of keratinized gingiva (WKT) and clinical attachment loss (CAL) were evaluated at 140 lower incisors. Incisors inclination (1-:ML), skeletal class (ANB, WITS), intermaxillary angle (NL:ML) and mandibular symphysis dimensions (symph. length and width) were assessed in cephalograms. Spearman’s correlation coefficient was used for statistical analysis at the P < 0.05 level.

Results

A statistically significant positive moderate correlation was found for GT and WITS and also symph. length. WKT correlated positively with ANB, WITS and symph. length, with moderate strength of the correlation. GRW, GRH and CAL did not correlate with any cephalometric parameters.

Conclusion

The results of this study indicated evidence for an association between WKT and GT and some cephalometric variables—ANB, WITS, and symphysis length.

Management of Maxillary Impacted Teeth and Complex Odontome: A Review of Literature and Case Report

BACKGROUND

Teeth impaction has become a common problem faced by orthodontic clinicians with the greatest incidence reported among third molars and maxillary canines. The great challenge lies in successfully treating these cases without deleteriously affecting the impacted as well as adjacent teeth while achieving acceptable functional and esthetic results. Several etiological factors have been associated with impactions including the presence of an odontome which is an asymptomatic odontogenic hamartomatous lesion.

CASE REPORT

This article presents a detailed orthodontic assessment and treatment of a 16 years old female having impacted right maxillary lateral incisor and canine caused by complex odontome.

CONCLUSION

Successful orthodontic treatment of multiple impactions can be achieved with minimal side effects even when odontomes are associated, through 3D radiographic examination, detailed evaluation as well as proper biomechanical control.

Correlation between the cross-sectional morphology of the mandible and the three-dimensional facial skeletal pattern: A structural equation modeling approach

OBJECTIVE

To clarify the relationship between the cross-sectional morphology of the mandible and vertical, transverse, and anteroposterior facial skeletal patterns using statistical shape analysis and structural equation modeling (SEM).

MATERIALS AND METHODS

We used 150 cone beam computed tomography (CBCT) images to obtain three-dimensional (3D) facial landmarks and cross-sectional images of the mandible. The morphology of the inner and outer cortices of the mandible was analyzed using statistical shape analysis, including generalized Procrustes analysis and principal component analysis (PCA). Factor analysis was performed to determine factors pertaining to the skeletal measurements and shape variations for the inner and outer cortices, following which a structural equation model was constructed.

RESULTS

Using factor analysis, characteristics of the vertical, transverse, and anteroposterior facial skeletal patterns were determined. PCA of the cross-sectional morphology of the mandible revealed 70% of the cumulative proportion by PC1 and PC2 after generalized Procrustes superimpositions. SEM showed complex relationships between the facial skeletal patterns and variations in the cross-sectional morphology of the mandibular cortices. The influence of the transverse factors on the outer cortex as a latent variable was relatively significant ( P = .057). However, the influence of the vertical factors on the outer and inner cortices was not significant.

CONCLUSIONS

The transverse skeletal pattern is associated with the morphology of the outer cortex of the mandible.

Effect of caspases and RANKL induced by heavy force in orthodontic root resorption

Objective

Orthodontic root resorption (ORR) due to orthodontic tooth movement is a difficult treatment-related adverse event. Caspases are important effector molecules for apoptosis. At present, little is known about the mechanisms underlying ORR and apoptosis in the cementum. The aim of the present in vivo study was to investigate the expression of tartrate-resistant acid phosphatase (TRAP), caspase 3, caspase 8, and receptor activator of nuclear factor kappa-B ligand (RANKL) in the cementum in response to a heavy or an optimum orthodontic force.

Methods

The maxillary molars of male Wistar rats were subjected to an orthodontic force of 10 g or 50 g using a closed coil spring. The rats were sacrificed each experimental period on days 1, 3, 5, and 7 after orthodontic force application. And the rats were subjected to histopathological and immunohistochemical analyses.

Results

On day 7 for the 50-g group, hematoxylin and eosin staining revealed numerous root resorption lacunae with odontoclasts on the root, while immunohistochemistry showed increased TRAP- and RANKL-positive cells. Caspase 3- and caspase 8-positive cells were increased on the cementum surfaces in the 50-g group on days 3 and 5. Moreover, the number of caspase 3- and caspase 8-positive cells and RANKL-positive cells was significantly higher in the 50-g group than in the 10-g group.

Conclusions

In our rat model, ORR occurred after apoptosis was induced in the cementum by a heavy orthodontic force. These findings suggest that apoptosis of cementoblasts is involved in ORR.

Evaluation of root resorption after comprehensive orthodontic treatment using cone beam computed tomography (CBCT): a meta-analysis

Background

Orthodontic treatment can result in root resorption (RR). Traditional two-dimensional (2D) data exhibit magnification, deformation and positioning problems. Cone beam computed tomography (CBCT) contains more accurate three-dimensional (3D) information. This study identified and qualified the extent and location of root resorption using cone beam computed tomography (CBCT) after comprehensive orthodontic treatment.

Methods

Studies comparing the RR before and after comprehensive orthodontic treatment using CBCT were identified using electronic searches of databases, including Cochrane, PubMed, EMBASE, China National Knowledge Infrastructure (CNKI) and Web of Science, and manual searches in relevant journals and the reference lists of the included studies until Oct 25, 2017. The extraction of data and the risk of bias evaluation were conducted by two investigators independently. The methodological quality of the included studies was assessed using the methodological index for non-randomized studies (MINORS). Studies that reported the length and volume of teeth were used for quantitative analyses.

Results

Twelve studies were included in the meta-analysis. The length of all teeth after intervention was significantly shorter than that before treatment (MD = 0.80, 95% CI 0.56, 1.03, P < 0.00001). The sequence of RR from heaviest to lightest was maxillary lateral incisors, maxillary central incisors, mandibular anterior teeth, and maxillary canines. Studies were divided into two subgroups based on the use of tooth extraction. Root shortening after treatment was observed in both groups, and extraction caused more root resorption than was observed in the non-extraction group.

Conclusions

There were different degrees of root resorption after orthodontics, but it was clinically acceptable. Root resorption established in CBCT research was less serious and more accurate than that observed in the two-dimensional research. Current evidence suggests that root length and volume were reduced after orthodontic treatment. The order of the amount of RR was maxillary lateral incisors, maxillary central incisors and mandibular anterior teeth. Most of the articles were complicated by different confounding factors. Therefore, more high-quality clinical trials are needed to determine the risk factors of root resorption and optimal protocols for treatment and to draw more reliable conclusions.

Volumetric evaluation of root resorption on the upper incisors using cone beam computed tomography after 1 year of orthodontic treatment in adult patients with marginal bone loss

OBJECTIVES:

To determine upper incisor root resorption, volume loss, and the relationship between root volume loss and tooth movement after 1 year of orthodontic treatment in patients with marginal bone loss.

MATERIALS AND METHODS:

A total of 30 women (46.3 ± 5.4 years old) with moderate upper incisor bone loss who required intrusion during orthodontic treatment were recruited. Pre- and post-treatment cone beam computed tomography images were reconstructed. Upper incisors at pre- and post-treatment were superimposed; labio- and palato-apical, middle, and coronal third root volumes were assessed. Tooth movement and alveolar bone height were measured from lateral cephalometric radiographs and cone beam computed tomography. Changes in root volume/alveolar bone height were compared using paired-sample t-tests, percentage root volume loss for each tooth/segment was evaluated by one-way analysis of variance, and the relationship between percentage root loss and degree of tooth movement was assessed by linear regression.

RESULTS:

Mean root volume significantly decreased on the labio- and palato-apical aspects of 12 and labio-apical aspects of 21 and 22 ( P ≤ .024). Palato-apical segment volume loss was greater on lateral than central incisors ( P ≤ .016). Two-dimensional root length and cementoenamel junction-bone crest distance did not change between T0 and T1, with no significant relationship between tooth movement amount and percentage root volume loss.

CONCLUSIONS:

Delivery of 40 g intrusive force to the four upper incisors using a T-loop and the leveling phase lead to more apical root volume loss on lateral than central incisors. There was no relationship between extent of tooth movement and upper incisor root volume loss.

Effects of loxoprofen on the apical root resorption during orthodontic tooth movement in rats

Studies have revealed that severe apical root resorption during tooth movement is caused by the noninfective inflammatory reaction of apical root tissues. We hypothesized that loxoprofen can suppress apical root resorption during tooth movement. Cyclic tensile force (CTF) of 10 kPa was applied to the human pulp cells for 48 hours by the Flexcell Strain Unit. Loxoprofen (10 and 100 μM) was added to the culture cells, and expression of cyclooxygenase (COX)-1, COX-2, interleukin (IL)-1β, receptor activator of nuclear factor kappa-B ligand (RANKL), tumor necrosis factor (TNF)-α, and macrophage colony-stimulating factor (M-CSF) were examined. To determine the effects of loxoprofen sodium on apical root reabsorption during tooth movement, the upper first molars of 7-week-old rats were subjected to mesial movement by 10g force for 30 days with or without the oral administration of loxoprofen. Gene expression and protein concentration of COX-1, COX-2, IL-1β, TNF-α, RANKL and M-CSF were significantly higher in the CTF group than in the control group. However, these levels were decreased by loxoprofen administration. After orthodontic tooth movement, the expression of IL-1β, TNF-α, RANKL and M-CSF decreased in the loxoprofen group than in the control group by immunohistochemical staining. In comparison to control group, less number of odontoclasts and a decrease in the amount of apical root resorption was observed in the loxoprofen group. Many osteoclasts became visible on the pressure side of the alveolar bone in the both groups, and the amount of tooth movement did not show a significant difference. These findings demonstrate that severe apical root resorption may be suppressed by loxoprofen administration, without a disturbance of tooth movement.

Root resorption during orthodontic treatment with Invisalign®: a radiometric study

Background

Root resorption (RR) is described as a permanent loss of tooth structure from the root apex. Many reports in the literature indicate that orthodontically treated patients are more likely to have severe apical root shortening, interesting mostly maxillary, followed by mandibular incisors. The aim of the study was to investigate the incidence and severity of RR in adult patients treated with aligners. The study group consisted of 71 class I adult healthy patients (mean age 32.8 ± 12.7) treated with aligners (Invisalign®, Align Technologies, Santa Clara, CA, USA). All incisors, canines, upper first premolars, and first molars were assessed. Root and crown lengths of 1083 teeth were measured in panoramic radiographs at the beginning (T0) and at the end (T1) of clear aligner therapy. Individual root-crown ratio (RCR) of each tooth and therefore the relative changes of RCR (rRCR) were determined. A decrease of rRCR was assessed as a reduction of the root length during treatment.

Results

All patients had a minimum of one teeth affected with a reduction of root length, on average 6.38 ± 2.28 teeth per patient. Forty one, 81% of the 1083, measured teeth presented a reduction of the pre-treatment root length. A reduction in percentage of >0% up to 10% was found in 25.94% (n = 281), a distinct reduction of >10% up to 20% in 12.18% (n = 132) of the sample. 3.69% (n = 40) of the teeth were affected with a considerable reduction (>20%).

Conclusions

Orthodontic treatment with Invisalign® aligners could lead to RR. However, its incidence resulted to be very similar to that described for orthodontic light forces, with an average percentage of RR < 10% of the original root length.

Torque differences due to the material variation of the orthodontic appliance: a finite element study

Background

Torque of the maxillary incisors is crucial to occlusal relationship and esthetics and can be influenced by many factors. The aim of this study was to assess the relative influence of the material of the orthodontic appliance (adhesive, bracket, ligature, and wire) on tooth displacements and developed stresses/strains after torque application.

Methods

A three-dimensional upper right central incisor with its periodontal ligament (PDL) and alveolus was modeled. A 0.018-in. slot discovery® (Dentaurum, Ispringen, Germany) bracket with a rectangular 0.018 x 0.025-in. wire was generated. The orthodontic appliance varied in the material of its components: adhesive (composite resin or resin-modified glass ionomer cement), bracket (titanium, steel, or ceramic), wire (beta-titanium or steel), and ligature (elastomeric or steel). A total of 24 models were generated, and a palatal root torque of 5° was applied. Afterwards, crown and apex displacement, strains in the PDL, and stresses in the bracket were calculated and analyzed.

Results

The labial crown displacement and the palatal root displacement of the tooth were mainly influenced by the material of the wire (up to 150% variation), followed by the material of the bracket (up to 19% variation). The magnitude of strains developed in the PDL was primarily influenced by the material of the wire (up to 127% variation), followed by the material of the bracket (up to 30% variation) and the ligature (up to 13% variation). Finally, stresses developed at the bracket were mainly influenced by the material of the wire (up to 118% variation) and the bracket (up to 59% variation).

Conclusions

The material properties of the orthodontic appliance and all its components should be considered during torque application. However, these in silico results need to be validated in vivo before they can be clinically extrapolated.

Electronic supplementary material

The online version of this article (doi:10.1186/s40510-017-0161-5) contains supplementary material, which is available to authorized users.

Comparisons of orthodontic root resorption under heavy and jiggling reciprocating forces during experimental tooth movement in a rat model

OBJECTIVE

Root mobility due to reciprocating movement of the tooth (jiggling) may exacerbate orthodontic root resorption (ORR). "Jiggling" describes mesiodistal or buccolingual movement of the roots of the teeth during orthodontic treatment. In the present study, buccolingual movement is described as "jiggling." We aimed to investigate the relationship between ORR and jiggling and to test for positive cell expression in odontoclasts in resorbed roots during experimental tooth movement (jiggling) in vivo.

METHODS

Male Wistar rats were divided into control, heavy force (HF), optimal force (OF), and jiggling force (JF) groups. The expression levels of cathepsin K, matrix metalloproteinase (MMP)-9 protein, interleukin (IL)-6, cytokine-induced neutrophil chemoattractant 1 (CINC-1; an IL-8-related protein in rodents), receptor activator of nuclear factor κB ligand (RANKL), and osteoprotegerin protein in the dental root were determined using immunohistochemistry.

RESULTS

On day 21, a greater number of root resorption lacunae, which contained multinucleated odontoclasts, were observed in the palatal roots of rats in the JF group than in rats from other groups. Furthermore, there was a significant increase in the numbers of cathepsin K-positive and MMP-9-positive odontoclasts in the JF group on day 21. Immunoreactivities for IL-6, CINC-1, and RANKL were stronger in resorbed roots exposed to jiggling than in the other groups on day 21. Negative reactivity was observed in the controls.

CONCLUSIONS

These results suggest that jiggling may induce ORR via inflammatory cytokine production during orthodontic tooth movement, and that jiggling may be a risk factor for ORR.

External root resorption with the self-ligating Damon system-a retrospective study

Background

The aim of this study was to compare the degree of external apical root resorption (EARR) in patients treated with self-ligating Damon appliances and with conventional preadjusted appliances.

Methods

The sample comprised 52 patients, divided into two groups. Group 1 consisted of 25 patients treated with self-ligating Damon appliances, with an initial age of 16.04 years, final age of 18.06 years, and treatment time of 2.02 years. Group 2 consisted of 27 patients, treated with conventional preadjusted appliances, with an initial age of 16.77 years, final age of 18.47 years and treatment time of 1.70 years. The groups were matched regarding the initial and final ages, treatment time, type of malocclusion, and treatment protocol without extractions. Root resorption was evaluated on periapical radiographs of the maxillary and mandibular incisors at the end of orthodontic treatment with the scores of Levander and Malmgren. Intergroup comparisons of root resorption were performed with Mann-Whitney tests.

Results

No significant difference in the degree of root resorption between the two groups was found.

Conclusions

Similar degrees of resorption can be expected after non-extraction treatment with Damon self-ligating or conventional preadjusted appliances.

Measurement accuracy and reliability of tooth length on conventional and CBCT reconstructed panoramic radiographs

INTRODUCTION:

This in vivo study assessed accuracy and reliability of tooth length measurements obtained from conventional panoramic radiographs and CBCT panoramic reconstructions to that of a digital caliper (gold standard).

METHODS:

The sample consisted of subjects who had CBCT and conventional panoramic radiographic imaging and who required maxillary premolar extraction for routine orthodontic treatment. A total of 48 teeth extracted from 26 subjects were measured directly with digital calipers. Radiographic images were scanned and digitally measured in Dolphin 3D software. Accuracy of tooth length measurements made by CBCT panoramic reconstructions, conventional panoramic radiographs and digital caliper (gold standard) were compared to each other by repeated measures one-way ANOVA with Bonferroni correction and by single measures intraclass correlation coefficient.

RESULTS:

Repeated root length measures with digital calipers, panoramic radiographs and CBCT constructed panoramic-like images were all individually highly reliable. Compared to the caliper (gold standard), tooth measurements obtained from conventional panoramic radiographs were on average 6.3 mm (SD = 2.0 mm) longer, while tooth measurements from CBCT panoramic reconstructions were an average of 1.7 mm (SD = 1.2 mm) shorter.

CONCLUSIONS:

In comparison to actual tooth lengths, conventional panoramic radiographs were relatively inaccurate, overestimating the lengths by 29%, while CBCT panoramic reconstructions underestimated the lengths by 4%.

Analysis of correlation between initial alveolar bone density and apical root resorption after 12 months of orthodontic treatment without extraction

OBJECTIVE

The aim of the present study was to investigate the correlation between initial alveolar bone density of upper central incisors (ABD-UI) and external apical root resorption (EARR) after 12 months of orthodontic movement in cases without extraction.

METHODS

A total of 47 orthodontic patients 11 years old or older were submitted to periapical radiography of upper incisors prior to treatment (T1) and after 12 months of treatment (T2). ABD-UI and EARR were measured by means of densitometry.

RESULTS

No statistically significant correlation was found between initial ABD-UI and EARR at T2 (r = 0.149; p = 0.157).

CONCLUSION

Based on the present findings, alveolar density assessed through periapical radiography is not predictive of root resorption after 12 months of orthodontic treatment in cases without extraction.

Torque efficiency of square and rectangular archwires into 0.018 and 0.022 in. conventional brackets

BACKGROUND

The aim of this study was to compare the torque efficacy of square and rectangular wires in 0.018- and 0.022-in. conventionally ligated brackets.

METHODS

Brackets of the same prescription were evaluated in both slot dimensions. Identical acrylic resin models of the maxilla were bonded with the brackets and mounted on the Orthodontic Measurement and Simulation System. Ten 0.018 × 0.018 in., 0.018 × 0.022 in., and 0.018 × 0.025 in. stainless steel wires were evaluated in the 0.018-in. brackets and ten 0.019 × 0.019 in., 0.019 × 0.025 in., and 0.019 × 0.026 in. stainless steel wires were evaluated in the 0.022-in. brackets. A 15° buccal root torque was gradually applied to the right central incisor bracket, and the moments were recorded at this position. One-way ANOVA was applied for both bracket slot sizes along with post hoc analysis for the various archwire sizes.

RESULTS

The mean measured moments varied between 10.78 and 30.60 Nmm among the assessed wire-and-bracket combinations. Both square and rectangular archwires in the 0.018-in. bracket system exerted statistically significantly higher moments in comparison with their counterparts in the 0.022-in. bracket system. Rectangular archwires exerted statistically significantly higher moments than square archwires, both for the 0.018- and the 0.022-in. bracket system.

CONCLUSIONS

Rectangular archwires seem to be more efficient in torque exertion, especially in 0.018-in. brackets.

Curve of Spee - from orthodontic perspective

The presence of a curve of Spee (COS) of variable depth is common finding in the occlusal arrangement and is sixth key of occlusion The understanding of COS in the field of orthodontics is very important as orthodontists deal with it in virtually every patient they treat. An excessive COS is a common form of malocclusion that may be addressed in many ways, including posterior extrusion, anterior intrusion, and incisor proclination. The specific approach to leveling of COS should be selected based on each patient's needs. Soft tissue, crown–gingival relations, occlusal plane, and skeletofacial concerns are among the special considerations for treatment planning for leveling of COS.

Differences in the mandibular premolar positions in Angle Class I subjects with different vertical facial types: A cone-beam computed tomography study

Objective

To compare the positions of the mandibular premolars in Angle Class I subjects according to vertical facial type. The results will provide a theoretical basis for predicting effective tooth movement in orthodontic treatment.

Methods

Cephalometric parameters were determined using cone-beam computed tomography in 120 Angle Class I subjects. Subjects were categorized as short, normal, and long face types according to the Frankfort mandibular angle. Parameters indicating the position of the mandibular right premolars and the mandible were also measured.

Results

The angle between the mandibular first premolar axis and buccal cortex, the distance between the root apex and buccal cortex, angle of vestibularization, arc of vestibularization, and root apex maximum movable distance were significantly greater in the short face type than in the long and norm face types. The angle between the mandibular second premolar axis and buccal cortex, the distance from root apex to buccal cortex, and the arc of vestibularization were significantly greater in the short face type than in the normal face type.

Conclusions

There are significant differences in the mandibular premolar positions in Class I subjects according to vertical facial type.

Assessing lower incisor inclination change: a comparison of four cephalometric methods

OBJECTIVE

Cephalometric inclination change of the lower incisors during orthodontics is used to assess treatment outcome. The lower border of the mandible is commonly used for measuring inclination change, despite it being subject to remodelling in growing patients. Superimposition of radiographs using Björk's 'stable structures' is intended to exclude these growth changes. We tested whether there is a significant difference for three commonly used methods to assess inclination change induced by orthodontic treatment (Me-Go, Go-Gn, the tangent to the lower border of the mandible) when comparing it to Björk's 'stable structures'.

METHODS

Björk's superimposition does not allow measuring incisor inclination changes directly; hence, one pre- and mid-treatment cephalogram of 39 growing orthodontic patients were superimposed in this retrospective study. The radiographs were taken at least 1 year apart (120 weeks; SD = 34.4). Patients undergoing growth modification treatment were excluded. Standardized cephalograms were hand traced and changes in lower incisor inclination, using the three mandibular planes, were compared to the changes obtained by anatomical superimposition of Björk's 'stable structures'.

RESULTS

Linear regression showed good intra-class correlation (ICC) between all methods. ICC was 0.96 for Me-Go, 0.94 for Go-Gn, and 0.92 for the lower border tangent. ICC for operator reliability was 0.99.

LIMITATIONS

Measurement errors affect all investigations of both analogue and digital radiographs, but movement artefacts particularly apply to the latter. Cephalometry uses two-dimensional measurements of a three-dimensional subject, which can lead to further inaccuracies. These limitations have to be taken into account when interpreting the results of our investigation.

CONCLUSION

Data obtained from Björk's superimposition did not vary significantly from the other more commonly used techniques (Me-Go, Go-Gn, and the tangent to the lower border of the mandible). Remodelling of the lower border of the mandible was insignificant for the time period investigated.

Radiologically determined orthodontically induced external apical root resorption in incisors after non-surgical orthodontic treatment of class II division 1 malocclusion: a systematic review

This study aims to critically evaluate orthodontically induced external apical root resorption (OIEARR) in incisors of patients undergoing non-surgical orthodontic treatment of class II division 1 malocclusion by a systematic review of the published data. An electronic search of two databases was performed; the bibliographies of relevant articles were also reviewed. Studies were included if they examined the amount of OIEARR in incisors produced during non-surgical orthodontic treatment of individuals with class II division I malocclusion in the permanent dentition. Individuals had no previous history of OIEARR, syndromes, pathologies, or general diseases. Study selections, risk of bias assessment, and data extraction were performed in duplicate. Eight studies of moderate methodological quality were finally included. An increased prevalence (65.6% to 98.1%) and mild to moderate severity of OIEARR (<4 mm and <1/3 original root) were reported. No sex difference in root resorption was found. For the maxillary incisors, there was no evidence that either the central or lateral incisor was more susceptible to OIEARR. A weak to moderate positive correlation between treatment duration and root resorption, and anteroposterior apical displacement and root resorption was found. Current limited evidence suggests that non-surgical comprehensive orthodontic treatment to correct class II division 1 malocclusions causes increased prevalence and severity of OIEARR the more the incisor roots are displaced and the longer this movement takes.

The effect of central incisor's root proximity to the cortical plate and apical root resorption in extraction and non-extraction treatment

Aims:

The present study was conducted to investigate the relevance of cortical plate proximity of maxillary central incisor root, maxillary alveolar bone width, and the apical root resorption in extraction and non-extraction orthodontically treated cases. Further, the correlation between the apical root resorption and the various parameters was investigated.

Materials and Methods:

A total of 80 lateral head cephalographs, 40 pre-treatment and 40 post-treatment, of orthodontic subjects with a mean age of 15 years treated with fixed standard edgewise appliance were obtained. All subjects were divided into two groups as extraction and non-extraction cases. Twelve linear and three angular parameters were measured and evaluated. The paired “t”-test, Pearson's correlation coefficient, and the stepwise regression analysis were done to test the relationship between the apical root resorption and the various parameters.

Results and Conclusions:

The study revealed slightly greater amount of apical root resorption in extraction subjects as compared to non-extraction subjects. However, no statistically significant difference was found between the two treatment modalities. In extraction subjects, the apical root resorption was directly proportional to the pre-treatment length of maxillary central incisor and inversely proportional to the root width in apical one-third region, though there was a weak correlation. In non-extraction subjects, the pre-treatment anteroposterior position of the root apex of maxillary central incisor in the alveolar bone, in combination with its root width in the apical one-third region formed the predictive factors for the variance in the amount of the apical root resorption, though there was a weak correlation. Furthermore, the changes in the alveolar widths at the root apex and mid-root region were considered as predictive factors for the amount of apical root resorption during extraction and non-extraction treatment, respectively.

The effect of orthodontic therapy on periodontal health: a review of the literature

Objectives. This review aims to evaluate the effect of orthodontic therapy on periodontal health. Data. Original articles that reported on the effect of orthodontic therapy on periodontal health were included. The reference lists of potentially relevant review articles were also sought. Sources. A literature search was conducted using the databases, Medline, EMBASE, Cochrane Library, Web of Science, Google Scholar, and Scopus databases for relevant studies. The search was carried out by using a combined text and the MeSH search strategies: using the key words in different combinations: “periodontal disease,” “orthodontics” and “root resorption.” This was supplemented by hand-searching in peer-reviewed journals and cross-referenced with the articles accessed. Articles published only in English language were included. Letters to the Editor, historical reviews and unpublished articles were not sought. Conclusions. Within the limitations of the present literature review, it was observed that there is a very close inter-relationship between the periodontal health and the outcome of orthodontic therapy.

Root resorption after leveling with super-elastic and conventional steel arch wires: a prospective study

BACKGROUND

The aim of this prospective study was to compare root resorption after the leveling phase of treatment, performed by either super-elastic or conventional multi-stranded stainless steel arch wires.

METHODS

From a total of 156 future orthodontic patients in a private clinic, 82 were included in the study after excluding those who earlier had orthodontic or endodontic treatment or signs of resorption. Patients were equally arbitrary allocated into two groups, where leveling was performed either with super-elastic heat-activated or conventional multi-stranded stainless steel arch wires. Root length loss was calculated using pre-treatment and post-leveling periapical radiographs.

RESULTS

The use of super-elastic arch wires did not significantly increase the severity of root resorption, except for tooth 31, while it reduced leveling time compared to conventional stainless steel wires. Crossbite of maxillary lateral incisors seemed to be a risk factor for resorption.

CONCLUSION

Incisor root resorption after leveling did not differ significantly between patients treated with super-elastic and conventional stainless steel arch wires, except for a mandibular incisor.

Root resorption, treatment time and extraction rate during orthodontic treatment with self-ligating and conventional brackets

INTRODUCTION

This study determined the amount and severity of EARR (external apical root resorption) after orthodontic treatment with self-ligating (SL) and conventional (Non-SL) brackets. Differences regarding rate of extraction cases, appointments and treatment time were evaluated.

MATERIAL AND METHODS

213 patients with a mean age of 12.4 ± 2.2 years were evaluated retrospectively. The treatments were performed with SL brackets (n = 139, Smartclip, 3 M Unitek, USA) or Non-SL brackets (n = 74, Victory Series, 3 M Unitek, USA). Measurements of the crown and root length of the incisors were taken using panoramic radiographs. Three-factor analysis of variance (ANOVA) was performed for an appliance effect.

RESULTS

There was no difference between patients treated with Non-SL or SL brackets regarding the amount (in percentage) of EARR (Non-SL: 4.5 ± 6.6 vs. SL: 3.0 ± 5.6). Occurrence of severe EARR (sEARR) did also not differ between the two groups (Non-SL 0.5 vs. SL: 0.3). The percentage of patients with need of tooth extraction for treatment (Non SL: 8.1 vs. SL: 6.9) and the number of appointments (Non-SL: 12.4 ± 3.4 vs. SL: 13.9 ± 3.3) did not show any differences. The treatment time was shorter with Non-SL brackets (Non-SL: 18.1 ± 5.3 vs. SL: 20.7 ± 4.9 months).

CONCLUSIONS

This is the largest study showing that there is no difference in the amount of EARR, number of appointments and extraction rate between conventional and self-ligating brackets. For the first time we could demonstrate that occurrence of sEARR does not differ between the two types of brackets.

Iatrogenic possibilities of orthodontic treatment and modalities of prevention

The benefits of orthodontic treatment are numerous and in most cases, the benefits outweigh the possible disadvantages. Orthodontic treatment can play an important role in enhancing esthetics, function, and self-esteem in patients. However, it carries with it the risks of enamel demineralization, tissue damage, root resorption, open gingival embrasures in the form of triangular spaces, allergic reactions to nickel, and treatment failure in the form of relapse. These potential complications are easily avoidable by undertaking certain precautions and timely interventions by both the orthodontist and the patient. The orthodontist must ensure that the patient is aware of the associated risks and stress the importance of the patient's role in preventing these untoward outcomes. The decision whether to proceed with the orthodontic treatment is essentially a risk-benefit analysis, where the perceived benefits of commencing treatment outweigh the potential risks. This article provides an overview of the iatrogenic possibilities of orthodontic treatment and the role of the patient as well as the orthodontist in preventing the associated risks.

Tooth resorption part II - external resorption: Case series

External tooth resorption usually follows trauma to the periodontal ligament. It can be classified into five categories based on its clinical and histological manifestations. Calcium hydroxide has long been used as an intracanal medicament to slow down the resorption process due to its alkaline pH. A combination of both external and internal resorptions can also occur on the same tooth, making the management more complex. Five case reports of external resorption have been presented in this article along with pertinent review of literature. Successful management was possible in two cases, while extractions had to be advised in 3 cases due to advanced nature of the lesions.

Significance of curve of Spee: An orthodontic review

Exaggerated curve of Spee is frequently observed in dental malocclusions with deep overbites. Such excessive curve of Spee alters the muscle imbalance, ultimately leading to the improper functional occlusion. It has been proposed that an imbalance between the anterior and the posterior components of occlusal force can cause the lower incisors to overerupt, the premolars to infraerupt, and the lower molars to be mesially inclined. This altered condition requires specialized skills for the practitioner. It would be useful if we have a thorough knowledge of how and when this curve of Spee develops, so that it will aid us in our treatment. The understanding of why the curve of Spee develops is limited in literature. The purpose of this article is to increase our knowledge regarding the development and its effect on dentition and its treatment in exaggerated cases.

Severe external apical root resorption--local cause or genetic predisposition?

BACKGROUND

Current data suggest that a large extent of the variation in orthodontic root resorption may be explained by differences in individual genetic predisposition. This would imply, however, a similar root resorption reaction in all teeth.

OBJECTIVE

To determine the incidence and extent of severe external apical root resorptions (SEARR) in maxillary incisors during multibracket (MB) appliance treatment.

PATIENTS AND METHODS

Of the whole sample of patients having completed MB treatment at the University of Giessen between 1991 and 2010 (P(Total)=3198), all subjects exhibiting severe root resorptions on at least one maxillary incisor were selected. SEARR were defined according to Malmgren et al. [39] (grade-IV RR=resorption >1/3 root length). Evaluation was performed using orthopantomograms from before and after MB treatment. The crown and root length of the affected teeth were measured. The extent of SEARR was assessed taking pretreatment crown length into consideration.

RESULTS

SEARR was detected in 16 patients. Thus, the incidence of SEARR on maxillary incisors during MB treatment totalled 0.5%. The median of SEARR of the affected incisors was 38.6% of the initial root length (minimum=33.4%, maximum=61.0%). Most subjects exhibited only single affected teeth. Only two subjects (0.06% absolute/12.5% relative) presented four maxillary incisors with SEARR.

CONCLUSIONS

The incidence of SEARR on maxillary incisors during MB treatment (0.5%) was very low compared to the literature. With only 12.5% of SEARR patients presenting four affected teeth, local rather than systemic/genetic factors seem to have predisposed the present subjects to SEARR.

External root resorption after orthodontic treatment: a study of contributing factors

Purpose

The purpose of this study was to examine the patient- and treatment-related etiologic factors of external root resorption.

Materials and Methods

This study consisted of 163 patients who had completed orthodontic treatments and taken the pre- and post-treatment panoramic and lateral cephalometric radiographs. The length of tooth was measured from the tooth apex to the incisal edge or cusp tip on the panoramic radiograph. Overbite and overjet were measured from the pre- and post-treatment lateral cephalometric radiographs. The root resorption of each tooth and the factors of malocclusion were analyzed with an analysis of variance. A paired t test was performed to compare the mean amount of root resorption between male and female, between extraction and non-extraction cases, and between surgery and non-surgery groups. Correlation coefficients were measured to assess the relationship between the amount of root resorption and the age in which the orthodontic treatment started, the degree of changes in overbite and overjet, and the duration of treatment.

Results

Maxillary central incisor was the most resorbed tooth, followed by the maxillary lateral incisor, the mandibular central incisor, and the mandibular lateral incisor. The history of tooth extraction was significantly associated with the root resorption. The duration of orthodontic treatment was positively correlated with the amount of root resorption.

Conclusion

These findings show that orthodontic treatment should be carefully performed in patients who need the treatment for a long period and with a pre-treatment extraction of teeth.

Biological markers for evaluation of root resorption

BACKGROUND

External apical root resorption is a pathologic consequence of orthodontic tooth movement. Cementum and dentin are removed from the root surface while active force is present.

OBJECTIVE

The aim of this study was to identify and quantify extracellular matrix proteins, dentin matrix protein 1 (DMP1), dentin phosphophoryn (PP), and dentin sialoprotein (DSP) in the gingival crevicular fluid (GCF) of subjects undergoing orthodontic treatment.

METHODS

Subjects with mild (less than 2mm) and severe (more than 2mm) root resorption during orthodontic treatment were identified by radiographs. A control group of subjects with neither signs of root loss nor undergoing orthodontic treatment was also identified. GCF was collected from the upper incisors by using filter paper strips (Periopaper). The absorbed GCF was eluted and the proteins were separated by SDS-PAGE analysis and stained. Western blot and ELISA were also performed. One-way ANOVA and Scheffé test were used for statistical analysis.

RESULTS

SDS-PAGE analysis identified proteins at 77, 66, 55, 50 and 26kDa. Immunoblotting did not show any differential expression pattern between control and study groups. ELISA results revealed a significant difference in the concentrations of DMP1, PP and DSP between control and root resorption groups. Concentration of PP and DSP in severe root resorption group was also statistically higher than in mild root resorption group.

CONCLUSION

DSP and PP could be suitable biological markers for monitoring root resorption during orthodontic treatment, since a significant difference in the level of these dentin specific proteins is detected in all groups.