Genetic Factors in External Apical Root Resorption and Orthodontic Treatment

Genetic and other factors contributing to external apical root resorption in orthodontic patients

OBJECTIVE

External apical root resorption (EARR) is a multifactorial disorder with adverse clinical outcomes in orthodontic practices often resulting in significant root shortening. This study examined the effect that specific single nucleotide polymorphisms (SNPs) have on the risk of developing EARR in orthodontic patients in X. We also evaluated how other selected patient- and treatment-related factors may contribute to root resorption in these patients.

SETTING/SAMPLE

Patients included in this case-control study were treated at the University of Alabama at Birmingham School of Dentistry, Department of Orthodontics.

METHODS

Panoramic radiographs were used to measure root resorption of the maxillary incisors. EARR was recorded when at least 20% of the root length had been lost with orthodontic treatment. Factors evaluated for association with EARR included ethnicity, sex, age, dental and skeletal classifications, ANB, U1-SN, overjet, treatment type and time, and SNPs in IL-1A (rs1800587), IL-1B (rs1143634), IL-1RN (rs419598), P2RX7 (rs1718119 and rs2230912), IRAK1 (rs1059703) and CASP1 (rs530537, rs580253 and rs554344). Chi-square test, Student's t test, Wilcoxon test, Benjamin-Hochberg false discovery rate (FDR) adjustment and logistic regression were used to analyse the data. The significance level was defined as P < .05.

RESULTS

We found that extraction treatment protocol and dental classification displayed significant association with root resorption. Furthermore, the GG genotype of IL-1A rs1800587 variant (in individuals with an increased overjet) predisposed Caucasians to EARR. While CASP1 (rs530537) variant may contribute to the risk of root resorption, it was not statistically significant after FDR adjustment (P = .09).

CONCLUSIONS

Both patient- and treatment-related factors contributed to EARR.

A comparison between two orthodontic archwire sequences in terms of speed of alignment and root resorption: a randomized controlled clinical trial

OBJECTIVES

To compare between two archwire (AW) sequences in terms of alignment speed and root resorption (RR).

MATERIALS AND METHODS

Fifty-four patients (14 males, 40 females) requiring orthodontic treatment were randomly allocated into two groups; in group A (mean age 18.3) treatment started with 0.014″ nickel titanium (NiTi) followed by 0.019″×0.025″ NiTi AW while group B (mean age 18.9) the AW sequence was 0.014″ NiTi, 0.018″ NiTi, 0.016″×0.022″ NiTi, 0.019″×0.025″ NiTi. The primary outcome was to compare the alignment speed of the crowded upper and lower teeth between the two different AW sequences. The secondary outcome was to assess the magnitude of upper and lower incisors' root resorption (RR) measured by digital periapical radiographs taken at the start of treatment and 1 month after the placement of the working AW. t-test was used to compare the alignment speed and RR between the two groups. Statistical significance was predetermined at the P ≤ 0.05 level for all tests.

RESULTS

The 54 patients were randomized in a 1:1 ratio to either group. Seven patients were excluded and complete data were obtained for 47 patients; 24 and 23 patients in group A and group B, respectively. There was no significant difference between the two groups in the alignment speed in the lower arch (P>0.05, mean difference=-0.44, 95% CI=-0.9 to 0.03) and root resorption (P>0.05). Alignment of upper arch was faster in group A (P < 0.0001, mean difference= - 0.9, 95% CI =-1.4 to -0.5).

CONCLUSIONS

There is no significant difference between the two groups in the alignment speed in the lower arch and incisors' RR. Upper arch alignment was faster in group A.

TRIAL REGISTRATION

Not registered.

Relationship of Vitamin D Deficiency with Cervical Vertebral Maturation and Dental Age in Adolescents: A Cross-Sectional Study

Background. Considering the high prevalence of vitamin D deficiency and its effect on growth and development, the assessment of the dental age and skeletal age with regard to vitamin D deficiency status could influence the treatment planning of growth modification treatment. This study aimed to assess the relationship between vitamin D deficiency, cervical vertebral maturation (CVM) as an indicator of skeletal age, and dental age in adolescent patients. Methods. In this cross-sectional study, the chronological age of 52 orthodontic patients aged between 10 and 14 years was recorded, and their serum level of vitamin D was determined using a radioimmunoassay test. The patients were then divided into three groups based on their serum vitamin D level: severe deficiency, moderate deficiency, and the control group with normal vitamin D. The panoramic radiographs of patients were assessed to determine their dental age using Demirjian’s method. CVM was determined on lateral cephalograms using Baccetti’s classification to specify the skeletal age. Data were analyzed using a t-test, linear regression, ordinal logistic regression, and Pearson’s correlation coefficient (at $P<0.05$ , confidence interval = 95%). Results. Skeletal age showed a significant difference between the group with severe vitamin D deficiency and the control group ( $P=0.01$ ); however, such difference was not observed between the group with moderate vitamin D deficiency and the control group ( $P=0.12$ ). Dental age was not significantly different between the groups with vitamin D deficiency and the control group ( $P=0.26$ for severe, and $P=0.39$ for moderate deficiency). Conclusions. A less advanced skeletal maturation was observed in adolescents with severe vitamin D deficiency; however, dental development was not affected by this deficiency. Vitamin D status is better to be considered in decision-making for the initiation of growth modification orthodontic treatments.

Targeted next-generation sequencing for comprehensive genetic analysis of external apical root resorption during orthodontic treatment with premolar extraction in the Korean population

INTRODUCTION

External apical root resorption (EARR) is one of the most common unfavorable consequences of orthodontic treatment and causes loss of tooth structure. The present study aimed to investigate the genetics of EARR using next-generation sequencing comprehensively.

METHODS

Targeted next-generation sequencing was performed for comprehensive genetic analysis of 118 Korean orthodontic patients. The patients were divided into 2 groups on the basis of their EARR value. The association of clinical and genetic parameters with EARR was assessed using the χ2 test or t test for matched pairs, followed by Bonferroni correction and linear regression analysis. In addition, haplotype analysis and in silico prediction were conducted to evaluate functional effects.

RESULTS

No statistically significant difference was observed between clinical and treatment-related parameters and EARR. The single nucleotide polymorphisms SPP1 rs9138 (P = 0.001) and SFRP2 rs3810765 (P = 0.04) showed only nominal significance between EARR groups. However, these 2 SNPs were not significant after Bonferroni correction for multiple testing (cutoff P = 0.05/142 = 3.52 × 10-4). Variations in SPP1 rs9138 and SFRP2 rs3810765 may be related to EARR during orthodontic treatment. In summary, not only genes related to inflammatory reactions but also those related to Wnt signaling to affect the degree of EARR during orthodontic teeth movement.

Influence of clinical factors on the protective or deleterious impact of genetic variants in orthodontically induced external root resorption: an observational study

BACKGROUND

Prediction of susceptibility to Orthodontically Induced External Apical Root Resorption (OIEARR) has been hampered by the complex architecture of this multifactorial phenotype. The aim of this study was to analyze the impact of the interaction of multiple variables in the susceptibility to OIEARR.

METHODS

The study evaluated 195 patients requiring orthodontic treatment. Nine clinical and treatment variables, single nucleotide polymorphisms (SNPs) from five genes and variables interactions were analyzed as risk factors for OIEARR using a multiple linear regression model.

RESULTS

The model explained 29% of OIEARR variability (ANOVA: p < 0.01). Duration of treatment was the most important predictor and gender was the second, closely followed by premolar extraction. For genes encoding osteoprotegerin (OPG), the receptor activator of nuclear factor κ B (RANK) and the IL1 receptor antagonist (IL1RN), the effect of analyzed variants changed from protective to deleterious depending on the duration of treatment and the age of the patient.

CONCLUSIONS

This work shows that in OIEARR the impact of genetic susceptibility factors is dynamic changing according to clinical variables.

The influence of two photobiomodulation protocols on orthodontically induced inflammatory root resorption (a randomized controlled clinical trial)

Background

Controversial results have been reported regarding the impact of photobiomodulation (PBM) on orthodontically induced inflammatory root resorption (OIIRR). The aim of this study was to evaluate the influence of two PBM protocols, one of them requiring a high application frequency (on days 0, 3, 7, 14, then every 2 weeks), while the second requires less frequent applications (every 3 weeks), on OIIRR accompanying orthodontic treatment.

Methods

Twenty female patients were recruited for this randomized controlled trial, requiring the therapeutic extraction of maxillary first premolars, and they were randomly divided into 2 equal groups. In Group A, one side of the maxillary arch randomly received PBM on days 0, 3, 7, 14, and every 2 weeks thereafter, while in Group B, one side was randomly chosen to receive PBM every 3 weeks. The laser applied was a Diode laser with a wavelength of 980 nm, in a continuous mode. Canine retraction in both groups was carried out using closed-coil springs, delivering 150 g of force, and the force level was checked every 3 weeks, over a 12-week study period. Pre-retraction and post-retraction cone-beam computed tomography (CBCT) was done for the evaluation of OIIRR.

Results

No significant differences in the amount of OIIRR have been reported between the laser and control sides in both groups A and B. Also, no significant differences have been reported between the laser sides in both groups.

Conclusions

Photobiomodulation does not affect OIIRR, whether by increasing or decreasing its occurrence, with both laser application protocols. Therefore, it can be stated that PBM does not result in root resorption less than the commonly observed range elicited with conventional orthodontic treatment, and that it has no effect on OIIRR.

Trial registration Two Low-level Laser Irradiation Protocols on the Rate of Canine Retraction (NCT04926389), 15/06/2021—retrospectively registered. https://clinicaltrials.gov/ct2/show/NCT04926389.

Ectopic Eye Tooth Management: Photobiomodulation/Low-Level Laser Emission Role in Root Resorption after Fixed Orthodontic Treatment

Aim: This study evaluates the role of low-level laser emission/photobiomodulation (LE/P) in quantitative measurements of root resorption (QRR). The application of LE/P performed after each orthodontic activation with four types of treatment intervention (TI) on the root resorption (RR) after fixed orthodontic treatment (FOT) of the upper arch with ectopic eye tooth/teeth [EET] was investigated. Materials and Methods: Thirty-two orthodontic patients scheduled for FOT were selected and assigned to the four groups. These were LE/P + Self ligating bracket (SLB), LE/P + Conventional bracket (CB), non-photobiomodulation (non-LE/P) + SLB and non-LE/P + CB. Standard management stages of FOT were followed in the maxilla. Each patient received a single application of LE/P labially/buccally and palatally, a total of five different points were used during each activation or appointment. The main outcome measure was QRR in maxillary anteriors before and after FOT, assessed via cone-beam computed tomography (CBCT) using 3D OnDemand software. Results: Insignificant QRR was found between before and after FOT in SLB, CLB, and LE/P, non-LE/P groups (p > 0.05). QRR in the SLB vs. CB and LE/P vs. non-LE/P group was significantly different in 11, 13, and 23 (p < 0.05). QRR in the LE/P + SLB group (p < 0.05) was significantly different in 11, 13, and 23 than that in the other groups. The most severe QRR was found on 13 (0.88 ± 0.28 mm and 0.87 ± 0.27 mm) and 23 (1.19 ± 0.14 mm and 1.16±0.13 mm) in the CB and non-LE/P group (p < 0.001). LE/P + SLB showed a highly significant superior outcome (p < 0.001) in relation to non-LE/P + CB, the QRR of 23 were 0.813 ± 0.114 mm and 1.156 ± 0.166 mm, respectively. Conclusion: Significantly higher amounts of QRR were found in EET patients after FOT treated with the CB, non-LE/P, and non-LE/P + CB system and warrant further investigation to explore potential specific causes.

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.

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.

Bone turnover markers in gingival crevicular fluid and blood serum of patients with fixed orthodontic appliances

AIM

Bone remodelling can be followed through the bone turnover markers (BTMs). Aim of the present study was to record the fluctuation of an osteoclastic and an osteoblastic BTM [C-terminal telopeptide of type I collagen (CTX) and N-terminal pro-peptide of type I pro-collagen (PINP), respectively] in both the gingival crevicular fluid (GCF) and the serum of orthodontic patients before and after the initial application of orthodontic forces.

MATERIALS AND METHODS

Twenty-one Caucasian patients were prospectively evaluated. GCF and blood samples were collected in order to measure the selected biomarkers by ELISA at three time-points: exactly before, 5 days, and 14 days after bonding of the appliances. Standardized sample handling and patient preparation procedures were adopted in order to reduce pre-analytical variability.

RESULTS

GCF and serum CTX levels were found to be independent of age, although higher in the serum of female subjects. PINP levels were found higher in the serum of patients ≥25 years old, as well as in the GCF of males. A positive correlation between serum and GCF baseline PINP levels was observed.

LIMITATIONS

The effect of orthodontic treatment on bone remodelling might not be absolutely representative of the local bone microenvironment as the levels of the specific BTMs where measured within the GCF of the lower front teeth.

CONCLUSIONS

This is the first time PINP and CTX have been evaluated in the GCF and serum of orthodontic patients with fixed appliances. No statistically significant alterations of CTX and PINP levels in the GCF and the serum of patients were recorded over time during the initial stages of orthodontic treatment.

Association between Polymorphisms in the IL-1β, TNFRSF11B, CASP1, and IL-6 Genes and Orthodontic-Induced External Apical Root Resorption

Orthodontic-induced external apical root resorption (EARR) is a severe condition affecting the roots of the teeth, whose genetic causes have been inconclusive to date. The aim of the present study was to assess the influence of selected single nucleotide polymorphisms (SNPs) IL-1β, TNFRSF11B, CASP1, and IL-6 genes on post-orthodontic EARR. A sample of 101 patients with clearly assessable orthopantomograms and lateral cephalometric radiographs taken before and at the end of the orthodontic treatment was used to evaluate the presence of EARR. The association between genetic polymorphisms and EARR was assessed with the Chi² test. A binary logistic multi-level model was built to evaluate the ability of patient- and tooth-level variables to predict EARR occurrence. The overall prevalence of EARR resulted to be around 40%. Within the limitations of this study, a significant association was found between EARR presence and the SNP for the IL-1β gene but not for the TNFRSF11B, CASP1, and the IL-6 genes. The final multi-level model demonstrated that the SNP for the IL-1β gene increases the odds of developing EARR by around four times. Since there is currently no accurate method to determine which patients will develop EARR prior to orthodontic treatment, further studies are needed to investigate the predictive ability of further genetic variants on EARR development.

Evaluation of apical root resorption occurrence in orthodontic patients treated with fixed braces depending on selected clinical parameters

An aim of the work was analysis of the possible connections between the selected clinical parameters and external apical root resorption (EARR) in patients after orthodontic treatment.

The study comprised 101 persons, who underwent complex orthodontic treatment with the use of fixed braces (straight-arch technique).

The teeth chosen for measurement of resorption level were central and lateral incisors of mandible and maxilla, as well as maxillary first molars, which are the most susceptible to root resorption. The roots were measured on the basis of the dental radiographs taken before and at the end of treatment. The measurements were made on digital radiographs with the use of diagnostic software (Planmeca Romexis® Viewer), which allows the image filters ensure the highest precision when localizing roots end points. Proportional measurements of the chosen teeth were made with the use of Linge’s method and Linge’s method modified by Brezniak et al. For further analysis, the persons taking part in the study were divided into two groups depending on the presence of postorthodontic EARR or its lack, resulting from radiographic measurements: a control group comprising 61 patients without EARR (with 0.90 ≤ rRCR ≤ 1.00) and a study group including 40 patients with EARR (rRCR < 0.90). In statistical analysis there was used verification of statistical hypotheses based on the following tests: Pearson’s chi-squared test, Student’s t-test, Mann-Whitney U test.

On the basis of the made analyses and achieved results, it was found out that age, sex, type of skeletal malocclusion, increased overjet and overbite do not constitute risk factors for EARR occurrence. Excessive proclination of central and lateral incisors of mandible and maxilla predisposes to shortening the roots of these teeth during orthodontic treatment with fixed braces (p < 0.01).

The effect of single/multiple micro-osteoperforation on the rate of orthodontic tooth movement and its possible complications: A systematic review and meta-analysis

OBJECTIVE

Different surgical and non-surgical approaches have been proposed to accelerate tooth movement and decrease the duration of orthodontic treatments. Recently, less invasive techniques such as micro-osteoperforation (MOP) are becoming more common. Several clinical trials have been performed to analyse the effect of MOP. This systematic review with meta-analyses was done to evaluate the effect of MOP on the rate of orthodontic tooth movement (OTM) and its complications.

MATERIAL AND METHODS

Electronic search was done in PubMed and Cochrane database for studies published until January 2021. Comparative randomized clinical trial studies with 10 or more participants per group were included. The risk of bias (ROB) of the studies was assessed according to the Cochrane Collaborations tool. Meta-analyses were performed to assess the mean difference in tooth movement rate and compare the level of pain between MOP and control groups.

RESULTS

Among a total of 15 included studies, eight studies were at low ROB, while others had unclear ROB. Ten studies evaluated the effect of MOP on OTM rate in canine retraction, and related meta-analysis showed a significant difference between the MOP and control group [SMD=0.42; 95% CI=0.20 to 0.63, P<0.01]. Besides, quantitative analysis showed MOP caused no significant higher anchorage loss [SMD=0.01; 95% CI=-0.15 to 0.13, P=0.89] and pain [SMD=0.54; 95% CI=-0.25 to 1.33, P=0.18].

CONCLUSIONS

Overall, both single and multiple applications of MOP increased the rate of OTM. However, the meta-analysis results of the four studies with low risk of bias showed that there is no significant difference in the rate of tooth movement between MOP and control groups. Besides, it has been shown that MOP did not significantly increase the level of pain, anchorage loss, and periodontal complications.

Intermittent parathyroid hormone promotes cementogenesis via ephrinB2-EPHB4 forward signaling

Intermittent parathyroid hormone (PTH) promotes periodontal repair, but the underlying mechanisms remained unclear. Recent studies found that ephrinB2-EPHB4 forward signaling mediated the anabolic effect of PTH in bone homeostasis. Considering the similarities between cementum and bone, we aimed to examine the therapeutic effect of PTH on resorbed roots and explore the role of forward signaling in this process. In vivo experiments showed that intermittent PTH significantly accelerated the regeneration of root resorption and promoted expression of EPHB4 and ephrinB2. When the signaling was blocked, the resorption repair was also delayed. In vitro studies showed that intermittent PTH promoted the expression of EPHB4 and ephrinB2 in OCCM-30 cells. The effects of PTH on the mineralization capacity of OCCM-30 cells was mediated through the ephrinB2-EPHB4 forward signaling. These results support the premise that the anabolic effects of intermittent PTH on the regeneration of root resorption is via the ephrinB2-EPHB4 forward signaling pathway.

Polymorphisms of Encoding Genes IL1RN and P2RX7 in Apical Root Resorption in Patients after Orthodontic Treatment

External apical root resorption (EARR) is one of the most serious complications associated with orthodontic treatment. The aim of the study was to analyze the relationships between selected single nucleotide polymorphisms (SNPs) in Interleukin 1 receptor antagonist (IL1RN), purinoreceptor P2X7 (P2RX7) and EARR in patients after orthodontic treatment. The study comprised 101 patients who underwent a complex orthodontic treatment with a combination of fixed appliances. Roots were measured based on orthopantomograms and lateral cephalometric radiographs taken before and at the end of the treatment using diagnostic software. Proportional measurements of selected teeth were made using the modified Linge and Linge methods. Based on the presence or absence of EARR, patients were divided into two groups: control group, 61 patients without EARR (with 0.90 ≤ rRCR ≤ 1.00), and EARR group, 40 patients with EARR (rRCR < 0.90). Root resorption in selected groups was also evaluated with the scores of Malmgren and Levander. SNP analysis was performed using the real-time polymerase chain reaction (PCR) method. The analysis indicated that a specific haplotype of P2RX7 (rs208294) and IL1RN (rs419598) modified the risk of EARR development (p < 0.05), with a Bonferroni correction. The analysis of the P2RX7 and IL1RN gene polymorphisms showed that the presence of SNPs of these genes may predispose individuals to EARR. These findings indicate that EARR is a complex condition influenced not only by environmental factors and needs further study on the genetic risk factors.

Accelerated tooth movement in Rsk2-deficient mice with impaired cementum formation

Coffin–Lowry–Syndrome (CLS) is a X-linked mental retardation characterized by skeletal dysplasia and premature tooth loss. We and others have previously demonstrated that the ribosomal S6 kinase RSK2, mutated in CLS, is essential for bone and cementum formation; however, it remains to be established whether RSK2 plays also a role in mechanically induced bone remodeling during orthodontic tooth movement (OTM). We, therefore, performed OTM in wild-type (WT) mice and Rsk2-deficient mice using Nitinol tension springs that were fixed between the upper left molars and the incisors. The untreated contralateral molars served as internal controls. After 12 days of OTM, the jaws were removed and examined by micro-computed tomography (µCT), decalcified histology, and immunohistochemistry. Our analysis of the untreated teeth confirmed that the periodontal phenotype of Rsk2-deficient mice is characterized by alveolar bone loss and hypoplasia of root cementum. Quantification of OTM using µCT revealed that OTM was more than two-fold faster in Rsk2-deficient mice as compared to WT. We also observed that OTM caused alveolar bone loss and root resorptions in WT and Rsk2-deficient mice. However, quantification of these orthodontic side effects revealed no differences between WT and Rsk2-deficient mice. Taken together, Rsk2 loss-of-function accelerates OTM in mice without causing more side effects.

Long noncoding RNA expression profiles in intermittent parathyroid hormone induced cementogenesis

The aim of this study was to explore the involvement of long noncoding RNAs (lncRNAs) during intermittent parathyroid hormone (PTH) induced cementogenesis. Expression profiles of lncRNAs and mRNAs were obtained using high-throughput microarray. Gene Ontology enrichment analysis, Kyoto Encyclopedia of Genes and Genomes pathway analysis, and coding-noncoding gene coexpression networks construction were performed. We identified 190 lncRNAs and 135 mRNAs that were differentially expressed during intermittent PTH-induced cementogenesis. In this process, the Wnt signaling pathway was negatively regulated, and eight lncRNAs were identified as possible core regulators of Wnt signaling. Based on the results of microarrray analysis, we further verified the repressed expression of Wnt signaling crucial components β-catenin, APC and Axin2. Above all, we speculated that lncRNAs may play important roles in PTH-induced cementogenesis via the negative regulation of Wnt pathway.

A randomized trial on the effects of root resorption after orthodontic treatment using pulsating force

Background

An orthodontic device that moves teeth with pulsating force was invented and underwent a single center, controlled, clinical trial to test its safety and efficacy for treatment. The device has a custom-made thermo-plastic mouthpiece which fits over the teeth with an inflatable silicone element. A console that measures and controls the pulsating force level in real-time controls the air pressure that delivers a pulsating force. In this study, the effect of the device on root resorption during orthodontic treatment was evaluated using 3D cone beam computed tomography and compared with a control group of patients who received Invisalign treatment.

Methods

Twenty-eight subjects were enrolled in the investigational arm and 15 in the control group. Subjects were followed until the average score of the mandibular and maxillary teeth achieved a Little’s Irregularity Index of 1.5 mm or less.

Results

There were no adverse events reported throughout the study for either treatment arm. No clinically significant root resorption was observed for either group. The investigational device did not cause root resorption greater than the control group. Both devices produced a safety profile compared to current orthodontic techniques.

Conclusion

The investigational device did not produce more root resorption than similar conventional orthodontic appliances.

Trial registration

ClinicalTrials.gov, NCT03421886. Registered 12 January 2018 - Retrospectively registered.

External apical root resorption in orthodontic patients: molecular and genetic basis

External apical root resorption is one of the most deleterious complications after orthodontic treatment. Studies to explain the causal relationship between orthodontic tooth movement and external apical root resorption have been inconclusive till date. Individual variations in external apical root resorption sometimes overshadow the treatment related factors which indicate genetic predisposition and/or multifactorial etiology. Mechanism of root resorption is not completely understood. Inflammatory root resorption induced by orthodontic treatment is a part of process of elimination of hyaline zone. An imbalance between bone resorption and deposition may contribute to root resorption by the cementoclasts/osteoclasts. This narrative review article explains the molecular pathway involved in external apical root resorption and also role of various genes involved at different level. It also reviews the literature published during the past 20 years concerning the association studies linking EARR to genetic polymorphisms. This literature review provides an insight into genetic predisposition of external apical root resorption that can be used in orthodontic practice to enable 'high-risk' subjects to be identified on the basis of their genetic information before orthodontic treatment is initiated.

GWAS of Post-Orthodontic Aggressive External Apical Root Resorption Identified Multiple Putative Loci at X-Y Chromosomes

Personalized dental medicine requires from precise and customized genomic diagnostic. To conduct an association analysis over multiple putative loci and genes located at chromosomes 2, 4, 8, 12, 18, X, and Y, potentially implicated in an extreme type of external apical root resorption secondary to orthodontic forces (aEARR). A genome-wide association study of aEARR was conducted with 480 patients [ratio~1:3 case/control]. Genomic DNA was extracted and analyzed using the high-throughput Axiom platform with the GeneTitan^® MC Instrument. Up to 14,377 single nucleotide polymorphisms (SNPs) were selected at candidate regions and clinical/diagnostic data were recorded. A descriptive analysis of the data along with a backward conditional binary logistic regression was used to calculate odds ratios, with 95% confidence intervals [p < 0.05]. To select the best SNP candidates, a logistic regression model was fitted assuming a log-additive genetic model using R software [p < 0.0001]. In this sample the top lead genetic variants associated with aEARR were two novel putative genes located in the X chromosome, specifically, STAG 2 gene, rs151184635 and RP1-30E17.2 gene, rs55839915. These variants were found to be associated with an increased risk of aEARR, particularly restricted to men [OR: 6.09; 95%CI: 2.6–14.23 and OR: 6.86; 95%CI: 2.65–17.81, respectively]. Marginal associations were found at previously studied variants such as SSP1: rs11730582 [OR: 0.54; 95%CI: 0.34–0.86; p = 0.008], P2RX7: rs1718119 [OR: 0.6; 95%CI: 0.36–1.01; p = 0.047], and TNFRSF11A: rs8086340 [OR: 0.6; 95%CI: 0.38–0.95; p = 0.024]), found solely in females. Multiple putative genetic variants located at chromosomes X and Y are potentially implicated in an extreme phenotype of aEARR. A gender-linked association was noted.

No Clear Evidence for the Effect of Low-Level Laser Treatment on Orthodontically Induced Inflammatory Root Resorption: More Human Clinical Studies Are Needed

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION

Influence of low-level laser therapy on orthodontically induced inflammatory root resorption. A systematic review. Michelogiannakis D, l-Shammery D, Akram Z, Rossouw PE, Javed F, Romanos GE. Arch Oral Biol 2019;100:1-13.

SOURCE OF FUNDING

The authors reported that this article did not receive any specific grants from funding agencies in the public, commercial, or nonprofit sectors.

TYPE OF STUDY/DESIGN

Systematic review.

Morphologic evaluation of root resorption after miniscrew assisted en mass retraction in adult bialveolar protrusion patients

Background

Bialveolar protrusion is one of the most common chief complaints from the Asian orthodontic patients. Typical orthodontic treatment includes extraction of the bimaxillary premolars and en mass retraction of anterior tooth with maximum anchorage by placing miniscrews. However, excessive pursuit of profile improvement by retraction and intrusion of anterior teeth may result in root resorption, alveolar bone loss, even dehiscence. Thus this retrospective, analytical study was to evaluate the root resorption of anterior teeth after miniscrew assisted en mass retraction in adult bialveolar protrusion patients.

Materials and methods

Thirty six adult patients with bimaxillary protrusion had four first premolars extracted, and then miniscrews were placed to provide anchorage. CBCT scans were performed before (T1) and posttreatment (T2). A new improvement project introduced for 3D CBCT registration assessment of root morphology. The paired t-test was used to compare changes from T1 to T2. The relationship between the root resorption and the movement of anterior teeth were assessed by Pearson correlation coefficient analysis.

Results

The significant differences were only found in apical third of root and the largest resorption in apical third of the root is always noted in the palatal and distal sectors. Significant correlations were observed in the loss of root in distal and palatal sectors, the root length and volume decrease with the amount of anterior teeth retraction and intrusion.

Conclusion

The new 3D registration assessment of root morphology will be helpful for the clinicians. Pursuit of large retraction and intrusion leads to obvious anterior teeth root resorption.

Baicalin inhibits root resorption during tooth movement in a rodent model

OBJECTIVE

Baicalin mediates bone metabolism and has shown protective activity against periodontal tissue damage in a rat model of periodontitis. Therefore, we hypothesized that baicalin may inhibit the root resorption that occurs during orthodontic tooth movement and examined its effect on the histological changes in periodontal tissue that occur during tooth movement.

METHODS

First molars of rats were subjected to traction using excessive orthodontic force to produce a root resorption model. Rats in the baicalin group received baicalin for 3 weeks during tooth movement, and the amount of first molar movement on day 21 after the initiation of traction was measured by three-dimensional micro-computed tomography analysis. After tooth movement, tissue samples from the mesial and tension sides were collected, and successive horizontal sections were prepared and examined using hematoxylin-eosin and tartrate-resistant acid phosphatase (TRAP) staining and immunohistochemical staining for the receptor activator of NF-kB ligand (RANKL) and osteoprotegerin (OPG). The severity of root resorption was also determined by histological analysis.

RESULTS

There was no significant intergroup difference in tooth movement during the experimental exaggerated tooth movement. In comparison with the control group, the baicalin-treated group showed increased OPG expression, suppressed RANKL expression, and significantly fewer TRAP-positive cells in the first molars. The root resorption area was significantly smaller in the baicalin group.

CONCLUSIONS

Treatment with baicalin prevented root resorption without preventing tooth movement. Baicalin may be useful for the management of root resorption during orthodontic treatment.

Relationship between the polymorphism in the interleukin 1-β and the treatment time of patients subjected to a modified piezocision technique

Aim:

We aimed to evaluate the correlation between the polymorphism of the interleukin 1-Beta (IL1-β, +3954 C>T) and tooth movement, in a group of Colombian patients undergoing surgically accelerated orthodontic tooth movement.

Methods:

The study was nested to a controlled clinical trial. Blood samples were taken from 11 women and 29 healthy Colombian male volunteers between 18 and 40 years old, after 1 year of starting orthodontic treatment. The patients presented malocclusion class I, with grade II or III. To detect the genetic polymorphism of the nucleotide +3954 C to T in the IL-1β gene, we used a real-time PCR assay.

Results:

Eleven individuals presented the allele 2 (T) heterozygous with the allele 1 (T/C) and 19 individuals were homozygous for the allele 1 (C/C). When analyzing the presence of the SNP, no significant differences were found in any of the variables. The best treatment was reflected in Group 3 (selective upper and lower alveolar decortication and 3D collagen matrix) and Group 4 (only selective alveolar decortication in the upper arch, with 3D collagen matrix), with 27% and 35% more speed respectively than in the control group.

Conclusions:

Our analyses indicated that a reduction in the total treatment time can be mostly potentiated by using decortication and collagen matrices and not for the presence of the allele 2 in the IL-1β. Nevertheless, it is important that further studies investigate if the polymorphism could be associated with the speed of tooth movement and analyze the baseline protein levels.

Effect of interleukin-33 on cementoblast-mediated cementum repair during orthodontic tooth movement

OBJECTIVE

This study aims to uncover the role of interleukin-33 on cementoblast-mediated cementum repair.

METHODS

6-8-week-old C57BL/6 mice were used to establish the model of orthodontic tooth movement. Interleukin-33 and suppression of tumorigenicity2 (ST2) expressions were immunohistochemically detected in the periodontal tissue. In vitro, cementoblast-like (OCCM-30) cells were cultured in the presence of recombinant mouse interleukin-33 protein (rmIL-33) at a 1-14 d time frame. ST2 expressions were immunofluorescently labeled and quantitatively examined. The effects of interleukin-33 on cementoblast differentiation, mineralization and proliferation were examined by alkaline phosphatase, alizarin red staining and cell counting kit-8, respectively. To further clarify the effect of interleukin-33 on cementogenesis-related protein expressions, runt-related transcription factor 2 (RUNX2), osterix, osteopontin, bone sialoprotein(BSP), osteocalcin, osteoprotegerin (OPG) and receptor activator of NF-КB ligand (RANKL) expressions were examined by western blot.

RESULTS

Orthodontic load of high magnitude induces external apical root resorption, and increases interleukin-33 expression in the periodontal tissue of mice. Cells in the cementum express ST2. Interleukin-33 initially down-regulates but later recovers ST2 mRNA and protein levels in OCCM-30 cells. Interleukin-33 abates cementoblast differentiation and mineralization, and suppresses RUNX2, osterix, BSP and osteopontin expressions in OCCM-30 cells at the later stage of the culture period. Interleukin-33 enhances RANKL expression, and reduces the ratio of OPG/RANKL in OCCM-30 cells.

CONCLUSION

Orthodontic load of high magnitude induces interleukin-33 expression in the periodontal tissue. Interleukin-33 has a negative effect on cementogenesis via suppressing cementoblast differentiation, mineralization and cementogenesis-related protein expressions.

The role of sphingosine-1-phosphate signaling pathway in cementocyte mechanotransduction

Iatrogenic external root resorption can become a serious pathological condition with clinical tooth movement. Little is known regarding how cementum responds to mechanical loading in contrast to bone, especially under compressive stress. In the field of bone biology, several studies have established the contribution of sphingosine-1-phosphate (S1P) signaling in bone remodeling, mechanical transduction and homeostasis. As osteocytes and cementocytes share similar morphological and functional characteristics, this study aimed to investigate the mechanotransduction ability of cementocytes and to explore the contribution of S1P signaling under compressive stress induced mechanotransduction. We found that compressive stress inhibited major S1P signaling and promoted the expression of anabolic factors in IDG-CM6 cells, a novel immortalized murine cementocyte cell line. By inhibiting S1P signaling, we verified that S1P signaling played a vital role in regulating the expression of the mechanotransduction factors prostaglandin E2 (PGE₂) and β-catenin, as well as factors responsible for cementogenesis and cementoclastogenesis in IDG-CM6 cells. These results support the hypothesis that cementocytes act as key mechanically responsive cells in cementum, responding to compressive stress and directing local cementum metabolism.

Orthodontically induced root resorption: An updated review

Background/Aim: Root resorption is one of the most common consequences of orthodontic treatment. However, its mechanism, etiology factors, diagnostic methods and the possibility of root repair remain controversial topics. The aim of this paper is to provide an updated review of the current literature concerning the orthodontically induced root resorption. Material and Methods: A literature search was performed using Google Scholar, PubMed and Scopus search engines covering the period January 1930 until June 2019 corresponding to articles investigating the mechanism, etiology, methods of interpretation of root resorption and the stages of root repair. Results: The mechanism of orthodontically induced root resorption involves an interaction between several molecular signaling pathways, which result in the resorption of both cementum and dentin by odontoclasts/cementoclasts. Root resorption can be the result of both treatment and patient-related factors. The main risk factors include prolonged orthodontic treatments, heavy forces, specific tooth movements, method of force application, systemic/genetic factors and aberrant root morphology. Nevertheless, root resorption is repaired to some extend by cellular cementum. Conclusions: Orthodontically root resorption is an unavoidable complication mainly due to its multifactorial etiology. However, its severity can be minimized with careful planning and radiographic monitoring.

Clinical and histopathological characterization of root resorption in replanted teeth: Two case reports

RATIONALE

The frequency of tooth avulsion is on the rise due to increasing rates of maxillofacial trauma. Avulsed teeth present with varying degrees of root resorption, and are generally asymptomatic; therefore, they often go undiagnosed. The etiopathogenesis of root resorption in replanted teeth following avulsion remains unclear.

PATIENT CONCERNS

In case 1, the left upper lateral incisor became loose after 10 years of replantation. In case 2, the patient underwent tooth replantation after external root canal treatment due to tooth dislocation caused by trauma 8 years ago.

DIAGNOSIS

According to the medical history, clinical manifestations and imaging studies of the 2 patients, root resorption after replantation was diagnosed.

INTERVENTIONS

The teeth extraction was given to one patient. Besides the histological examination of extracted teeth was performed.

OUTCOMES

Teeth that underwent pulp treatment presented with external resorption. On the other hand, the tooth that had received no pulp treatment showed both external and internal resorption; residual vital pulp tissue was detected within the pulp cavity.

LESSONS

The dental pulp tissues may be involved in the initiation or development of internal resorption. Trauma to the periodontal ligament might play a major role in external resorption, whereas internal tooth resorption may be caused as a result of injury to the residual pulp tissue. Thus, the effective management of these tissues during the treatment of replanted teeth is essential.

External apical root resorption after nonextraction orthodontic treatment with labial vs. lingual fixed appliances

OBJECTIVES

The aim of this retrospective study is to compare external apical root resorption (EARR) after labial and lingual fixed orthodontic treatment, as detected with panoramic radiographs.

MATERIALS AND METHODS

Sixty subjects were divided into two groups according to the treatment type: lingual (30 patients) and labial (30 patients) fixed orthodontic treatment. Panoramic radiographs which were obtained at the beginning of treatment (T0) and at the end of the treatment (T1) were evaluated. The maxillary and mandibular central and lateral incisors, as well as canine crown and root lengths were measured for T0 and T1. Crown to root ratios were used to determine EARR. Data were evaluated using analysis of variance and χ² analysis.

RESULTS

In all, 5 patients (16.7%) in the lingual group and 7 patients (23.3%) in the labial group had a minimum of one tooth with severe EARR, while 9 patients (30%) in the lingual group and 14 patients (46.7%) in the labial group had no EARR. A total of 26 teeth (7.2%) in the lingual group and 34 teeth (9.4%) in the labial group developed severe EARR; however, 184 teeth (51.1%) in the lingual group and 202 teeth (56.1%) in the labial group did not reveal any EARR. No statistically significant difference was found for the resorption rates between the treatment groups (p > 0.05). Although not statistically significant, there was a higher percentage of severe EARR in the mandible within the labial group.

CONCLUSIONS

Both lingual and labial orthodontic techniques showed statistically similar root resorption rates. EARR is a multifactorial issue and individual predispositions must also be taken into consideration.

Predisposing factors for external apical root resorption associated with orthodontic treatment

Objective

This study aimed to identify possible risk factors for external apical root resorption (EARR) in the maxillary incisors after orthodontic treatment.

Methods

The root length of 2,173 maxillary incisors was measured on periapical radiographs of 564 patients who received orthodontic treatment. The Kappa test was performed to evaluate intraexaminer and interexaminer reproducibility. Multiple binary logistic regression was used to determine the association between EARR and various factors. Odds ratios and 95% confidence intervals were reported.

Results

The risk of developing EARR was 70% higher in orthodontic treatment with maxillary premolar extraction (p = 0.004), 58% higher in patients with increased overjet (p = 0.012), 41% lower in two-phase orthodontic treatment (p = 0.037), and 33% lower in patients with deep bite (p = 0.039). The lateral incisors were 54% more likely to develop EARR (p < 0.001), dilacerated roots were 2.26 times more likely to develop EARR (p < 0.001), and for each additional millimeter of root length, the risk of EARR increased by 29% (p < 0.001).

Conclusions

The potential risk factors for EARR after orthodontic treatment included treatment with maxillary premolar extraction, increased overjet at the beginning of treatment, and dilacerated roots.

Association of clinical variables and polymorphisms in RANKL, RANK, and OPG genes with external apical root resorption

OBJECTIVES

The aim of this study was to investigate the association of clinical variables and polymorphisms in the RANKL, RANK, and OPG genes with external apical root resorption (EARR).

METHODS

The sample was composed of 338 unrelated patients of both sexes, average age 14.9 years (range 8-21) with Class II Division 1 malocclusion, orthodontically treated. Periapical radiographs of the maxillary central incisor with the longer root (reference tooth) were taken before treatment and 6 months after starting treatment. DNA was extracted from buccal epithelial cells with the use of 10 mol/L ammonium acetate and 1 mmol/L EDTA. The analysis of 42 polymorphisms in the RANKL, RANK, and OPG genes was performed by means of real-time polymerase chain reaction. Univariate and multivariate analyzes were performed to verify the association of clinical and genetic variables with EARR (P <0.05).

RESULTS

The initial root length and patient age were associated with EARR. Considering the study of polymorphisms of RANKL, no significant association was found of genetic polymorphisms with EARR. For RANK polymorphisms, only rs12455775 was associated with EARR. Regarding OPG polymorphisms, an association of rs3102724, rs2875845, rs1032128, and rs3102728 with EARR was found. After multivariate analysis, the initial root length, rapid maxillary expansion, and rs3102724 of the OPG gene were associated with EARR.

CONCLUSIONS

Longer roots of upper central incisors and rapid maxillary expansion, as well as allele A of the rs3102724 polymorphism of the OPG gene, were associated with EARR in the study population.

Ethnic differences in the root to crown ratios of the permanent dentition

OBJECTIVE

Root resorption due to orthodontic tooth movement may adversely affect the root-crown (R/C) ratios of permanent teeth, especially in patients with Short Root Anomaly (SRA), a poorly understood disorder affecting root development. Evaluation of SRA R/C ratios to normal dentition would facilitate diagnosis and orthodontic treatment planning. However, reference values are not available for all ethnicities. Our goal was to determine R/C ratios of permanent teeth and their relationship to gender and ethnicity.

SETTING/SAMPLE

A retrospective study of 333 patients (109 Caucasians, 112 African Americans and 112 Hispanics) from the University of Alabama at Birmingham School of Dentistry.

MATERIALS/METHODS

Root lengths and crown heights were measured from panoramic radiographs of 6241 teeth using modified Lind's method. A linear mixed model was used to compare the R/C ratios of teeth among subgroups (gender, ethnicity).

RESULTS

The mean R/C ratios varied from 1.80 to 2.21 for the maxillary teeth and 1.83-2.49 for the mandibular teeth. Gender differences in R/C ratios were found to be significant only for the lower central incisors (P < 0.05). Hispanics showed significantly lower ratios for most teeth compared to the other two groups (P < 0.05). There were significant differences in R/C ratios between African Americans and Caucasians in the upper lateral incisors, lower central incisors and lower first premolars (P < 0.05).

CONCLUSION

Our results suggest that ethnicity is an important factor in determining the R/C ratios of permanent teeth. Therefore, when diagnosing developmental conditions such as SRA, ethnic group-specific reference values should be considered.

Clastic cells are absent around the root surface in pulp-exposed periapical periodontitis lesions in mice

INTRODUCTION

Clastic cells, originating from the monocyte-macrophage lineage, resorb mineralized tissues. In periapical periodontitis, alveolar bone around the tooth apex becomes resorbed; however, the roots of the teeth are often left intact by yet unknown mechanisms. Here, we examined the status of clastic cells in a periapical periodontitis model in mice.

METHODS

Periapical periodontitis was induced by performing pulp exposure on the maxillary first molar. The contralateral maxillary first molar was used as a control. The maxillae were harvested, fixed, and subjected to μCT scanning and three-dimensional volumetric analysis. TRAP staining was performed, and osteoclasts were quantified. Immunohistochemical staining was performed for RANKL, OPG, and F4/80, a marker for macrophages.

RESULTS

At the apex of the tooth, pulp exposure resulted in periapical radiolucency with mineralized tissues at the surrounding bone surfaces but not on the root surfaces. Histologically, clastic cells were present on the bone surfaces but absent around the root surfaces. Expression of F4/80 and RANKL was not found at close proximity to the root surfaces, but OPG was globally expressed.

CONCLUSION

The absence of clastic cells around the root surface of pulp-exposed teeth, in part, is associated with the lack of macrophages and RANKL expression.

Apical root resorption during orthodontic treatment with clear aligners: A retrospective study using cone-beam computed tomography

INTRODUCTION

We aimed to investigate the incidence and severity of orthodontically induced inflammatory root resorption (OIIRR) on maxillary incisors with clear aligner therapy using cone-beam computed tomography and to identify possible risk factors.

METHODS

The root lengths of maxillary incisors were measured on orthogonal images from pretreatment and posttreatment cone-beam computed tomography examinations of 160 patients who received comprehensive orthodontic treatment with clear aligners.

RESULTS

Mean absolute reductions in root length varied between 0.47 ± 0.61 mm and 0.55 ± 0.70 mm and were not significantly different between maxillary central and lateral incisors. The prevalence of severe OIIRR, defined as both maxillary central incisors experiencing greater than a 25% reduction in root length, was found to be 1.25%. Potential risk factors included sex, malocclusion, crowding, and posttreatment approximation of apices to the cortical plates. Race, interproximal reduction, previous trauma to the teeth, elastics, age, treatment duration, and pretreatment approximation of apices to the cortical plates did not significantly affect the amount of OIIRR.

CONCLUSIONS

Comprehensive treatment with clear aligners resulted in minimal root resorption. Sex, malocclusion, crowding, and posttreatment approximation to the cortical plates significantly affected the percentage of change in root length. Posttreatment approximation of root apices to the palatal cortical plate showed the strongest association for increased OIIRR.

Incisor root resorption in class II division 2 patients in relation to orthodontic treatment

Background/Objectives

The aims were 1. to analyse differences in the occurrence of orthodontic induced inflammatory root resorption (OIIRR) of the upper and lower incisors in Angle Class II division 2 patients, between patients treated with fixed appliance only (one-phase treatment group) and patients treated with removable appliance before treatment with fixed appliance (two-phase treatment group) and 2. to analyse differences in OIIRR between treatment time, age, gender, craniofacial morphology and deviations in the dentition for the two groups together.

Materials/Methods

Seventy-four subjects treated for Class II division 2 malocclusion were divided into two groups: 46 patients in the one-phase treatment group (28 girls, 18 boys, mean age 14.4) and 28 patients in the two-phase treatment group (18 girls, 10 boys, mean age 12.4) where 336 and 201 incisors were analysed respectively. OIIRR was assessed on intra oral radiographs, deviations of the dentition were assessed on orthopantomograms and the craniofacial morphology was assessed on lateral cephalograms. Differences were tested by Fisher Exact test, McNemar, and multiple regression analysis.

Results

The one-phase treatment group showed significantly more OIIRR for lower central incisors (P = 0.002) compared to the two-phase treatment group. For the both groups combined, boys showed more OIIRR than girls (P = 0.002) and patients with agenesis showed more OIIRR than patients without agenesis (P = 0.019) for the lower central incisors.

Conclusion

The results indicate that two-phase treatment modalities may be considered as an option for Angle Class II division 2 patients with enhanced risk for OIIRR.

Physical properties of root cementum: Part 26. Effects of micro-osteoperforations on orthodontic root resorption: A microcomputed tomography study

INTRODUCTION

Studies have demonstrated the potential efficacy of micro-osteoperforations in accelerating tooth movement by amplifying the expression of inflammatory markers. The aim of this investigation was to examine the effects of micro-osteoperforations on orthodontic root resorption with microcomputed tomography.

METHODS

This prospective controlled clinical trial involved 20 subjects requiring extraction of the maxillary first premolars as part of their orthodontic treatment. A buccal tipping force of 150 g was applied to both premolars. Using the Propel appliance (Propel Orthodontics, San Jose, Calif), micro-osteoperforations were applied at a depth of 5 mm on the mesial and distal aspects in the midroot region of the experimental side of the first premolar root; the contralateral side served as the control. After 28 days, both premolars were extracted. The teeth were scanned under microcomputed tomography, and the volumes of root resorption craters were calculated and compared.

RESULTS

Premolars treated with micro-osteoperforation exhibited significantly greater average total amounts of root resorption than did the control teeth (0.576 vs 0.406 mm³). The total average volumetric root loss of premolars treated with micro-osteoperforation was 42% greater than that of the control teeth.

CONCLUSIONS

This 28-day trial showed that micro-osteoperforations resulted in greater orthodontic root resorption. However, these results should be verified in patients who are undergoing full-length orthodontic treatment.

Tooth root and alveolar bone grey values derived from cone-beam CT imaging in maxillary incisor teeth with and without apical root resorption

INTRODUCTION

In orthodontic treatment, an increased bone mineral density of the alveolar bone is considered as a risk factor for apical root resorption (ARR), whereas the mineral density of cementum has been associated with root protection against resorption.

METHODS

This study aimed at evaluating the grey values (GVs) of the apical third of the root and of the alveolar bone adjacent to maxillary incisors with and without ARR in orthodontic patients. Twenty-one patients under treatment who presented one incisor with ARR and its corresponding contralateral without ARR were selected and submitted to cone-beam computed tomography. GVs were evaluated on the images obtained of four areas of the apical third of the root and of four areas of the adjacent alveolar bone.

RESULTS AND CONCLUSIONS

The radicular tissue of the apical third of the incisors with ARR showed greater root GV (p < .05) than that of the incisors without ARR. Supra-apical alveolar bone exhibited greater GV in the incisors without ARR than incisors with ARR (p < .05). Root GV was not associated with root protection, but rather seemed to have facilitated the process of resorption. The GV of the lingual bone was associated with a higher progression of ARR in the incisors.

Comparison between anterior segmental osteotomy versus conventional orthodontic treatment in root resorption: a radiographic study using cone-beam computed tomography

Background

Patients who received orthodontic treatment are likely to have apical root shortening. It appears that external apical root resorption results from a combination of patient-related risk factors such as genetic influences, systemic factors, and orthodontic treatment-related factors. Regarding the fact that the anterior segmental osteotomy (ASO) has been known for its possibility of complementing external apical root resorption and of buffering periodontal problems, it has been the preferred treatment. However, the studies on the efficacy of ASO in preserving the root are not sufficient. In this study, we compared the amount of root resorption between the patients who only received orthodontic treatment and the patients who received orthodontic treatment with ASO.

Methods

This study included 28 patients (the number of incisor = 198) who received orthodontic treatment with or without ASO. We categorize them into groups A and B by the type of orthodontic treatment (group A: conventional orthodontic treatment; group B: orthodontic treatment with ASO). Cone-beam computed tomographic and cephalometric evaluations were retrospectively performed on the radiographs taken for the diagnosis of the treatment before treatment and at the end of active treatment.

Results

In group B, root resorption itself and its rate both turned out to have significantly lower than those in group A. Also, the change of incisal angle is significantly smaller in group B than in group A. On the other hand, in group A, the change of incisal angle was positively correlated with the change of AP (anteroposterior) position. In group B, the change of incisal angle was negatively correlated with the duration of the orthodontic treatment. In group B, amount of root resorption (mm) was positively correlated with the duration of the orthodontic treatment.

Conclusions

The results show lesser root resorption and shorter treatment duration with ASO than with conventional orthodontic treatment. Therefore, if the indications are accurately determined, ASO can be an effective treatment option when the amount of root resorption is expected to be high, especially in late adults.

Heredity, Genetics and Orthodontics - How Much Has This Research Really Helped?

Uncovering the genetic factors that correlate with a clinical deviation of previously unknown etiology helps to diminish the unknown variation influencing the phenotype. Clinical studies, particularly those that consider the effects of an appliance or treatment regimen on growth, need to be a part of these types of genetic investigations in the future. While the day-to-day utilization of "testing" for genetic factors is not ready for practice yet, genetic testing for monogenic traits such as Primary Failure of Eruption (PFE) and Class III malocclusion is showing more promise as knowledge and technology advances. Although the heterogeneous complexity of such things as facial and dental development, the physiology of tooth movement, and the occurrence of External Apical Root Resorption (EARR) make their precise prediction untenable, investigations into the genetic factors that influence different phenotypes, and how these factors may relate to or impact environmental factors (including orthodontic treatment) are becoming better understood. The most important "genetic test" the practitioner can do today is to gather the patient's individual and family history. This would greatly benefit the patient, and augment the usefulness of these families in future clinical research in which clinical findings, environmental, and genetic factors can be studied.

A preliminary investigation of short-term cytokine expression in gingival crevicular fluid secondary to high-level orthodontic forces and the associated root resorption: case series analytical study

BACKGROUND

Orthodontically induced iatrogenic root resorption (OIIRR) is an unavoidable inflammatory process. Several factors claimed to be related to the severity of OIIRR. Orthodontic forces cause micro-trauma to the periodontal ligament and activate a cascade of cellular events associated with local periodontal inflammation. The purpose of this split-mouth study were (1) to investigate the changes in cytokine profile in the gingival crevicular fluid (GCF) secondary to heavy orthodontic forces and (2) to compare the cytokine expression between participants showing high and low root resorption.

METHODS

Eight participants requiring maxillary first premolar extractions involved in this study. The teeth on the tested side (TS) received 225 g of controlled buccal tipping force for 28 days, while the contralateral teeth act as a control (CS). GCF was collected from both TS and CS teeth at 0 h (prior to application of force) and 3 h, 1 day, 3 days, 7 days and 28 days after the application of force, and analysed with multiplex bead immunoassay to determine the cytokine levels.

RESULTS

Statistically significant temporal increase was found in the TS teeth for tumour necrosis factor alpha (TNF-α) at 3 h and 28 days (p = 0.01). Interleukin 7 (IL-7) significantly peaked at the 28th day. Comparing cytokine profile for participants with high and low root resorption (>0.35 and <0.15 mm3, respectively), the levels of GM-CSF was significantly greater in low root resorption cases (p < 0.05). The amounts of root resorption which craters on mesial, distal surfaces and middle third region were significant in the TS teeth (p < 0.05).

CONCLUSIONS

IL-7 and TNF-α (pro-resorptive cytokine) increased significantly secondary to a high-level of orthodontic force application. Significantly high levels of granulocyte macrophage colony-stimulating factor (anti-resorptive cytokine) were detected in mild root resorption cases secondary to high-level orthodontic force application. A future long-term randomised clinical trial with larger sample taking in consideration gender, age and growth pattern distribution would be recommended.

Markers in blood and saliva for prediction of orthodontically induced inflammatory root resorption: a retrospective case controlled-study

BACKGROUND

Hormonal and enzymatic factors may render certain individuals more susceptible to orthodontically induced inflammatory root resorption (OIIRR). The objectives of this study are (1) to identify biochemical key markers in blood and saliva that may be correlated to the trend of extensive OIIRR and (2) to utilise these markers to predict a susceptible patient-receiving orthodontic treatment.

METHODS

Nine patients (mean age 23 + 2.9 years) who had moderate to severe OIIRR that assessed via orthopantomograms and met the inclusion criteria were classified as the root resorption group (RRG). Blood chemistry was evaluated using the collection of fasting blood and unstimulated saliva samples. Multiplex enzyme-linked immunosorbent assay (ELISA) arrays were used to screen blood and saliva samples for human cytokines, chemokines and several key enzymes that may play a role in root resorption following orthodontic force application. Biochemical findings from 16 matching subjects were used as the control (CG) for comparative measurements.

RESULTS

Patients with moderate to severe OIIRR showed a significant increase in salivary cytokines including interleukin (IL) 7, IL-10, IL-12p70 and interferon-gamma (IFN-γ) level as well as a significant decrease in IL-4 level. Osteocalcin and procollagen type I N-terminal peptide (P1NP) appeared to be the only blood factors that showed a significant difference, more in the CG than the RRG.

CONCLUSIONS

Saliva might be a more valuable way of measuring changes in cytokine expression than blood secondary to orthodontic treatment. Although the increased expression of pro-inflammatory and anti-inflammatory cytokines may be determinants in the development of moderate to severe OIIRR, cytokine expression may be affected by several potential inflammations in another part of the body. Future research could investigate the cause/effect relationship of different cytokines, in a larger group of patients and at different time intervals, using digital subtraction radiography techniques and microfluidic biosensors.

Root resorptions associated with canine retraction treatment

INTRODUCTION

The hypothesis of this study was that multiple factors are dominant in causing external apical root resorption (EARR). The objective of this investigation was to better understand the clinical factors that may lead to EARR.

METHODS

Maxillary cone-beam computed tomography scans of 18 subjects who were treated with bilateral canine retractions during orthodontics were used to calculate EARR. The subjects were treated using well-calibrated segmental T-loops for delivering a 124-cN retraction force and the moment-to-force ratio suitable for moving the canine under either translation or controlled tipping. The subjects' age, sex, treatment duration, and genotype were collected.

RESULTS

Six subjects of the 18 showed definite EARR, meaning that load was not the only causing factor. All 5 subjects with the genotype identified had GG genotype of IL-1β rs11143634, indicating that people with this genotype may be at high risk. Longer treatment duration, female sex, and older age may also contribute to EARR, although the findings were not statistically significant.

CONCLUSIONS

EARR appears to be related to multiple factors. The orthodontic load and the genotype should be the focuses for future studies.

Three-dimensional characterization of root morphology for maxillary incisors

The aim of this study was to test the reproducibility of three-dimensional (3D) surface models of maxillary incisors and to propose a characterization of root morphology. The sample was comprised of pre-treatment cone-beam computed tomography (CBCT) images of fifty-five patients. The CBCTs were used to construct 3D surface models of the maxillary incisors. The reproducibility of surface models was tested by repeated construction of them by two observers. A 3D surface model that corresponded to the average of all lateral and all central incisors was generated. 3D surface distances and vector differences were calculated for each individual tooth and the average of the teeth considered. The corresponding points on the 3D surface mesh for each subgroup were compared statistically to those of the neutral subgroup using shape analysis MANCOVA and Hotelling's t-statistic (p < 0.05). Repeated construction of surface models demonstrated adequate inter-rater reproducibility. The distribution of 3D models into root morphology subgroups was: blunt (11% and 26% of the central and lateral incisors, respectively), conical (15% of the central incisors), long (27% and 20% of the central and lateral incisors, respectively), and short (15% and 4% of the central and lateral incisors, respectively). Compared to the neutral average, statistically significant differences in root morphology were found for blunt, long, conical, and short central incisors and for blunt, long, and short lateral incisors. We can conclude that 3D surface models construction for upper incisors is reproducible. 3D shape analysis using CBCT images allows a phenotypic characterization of incisor root morphology.

External apical root resorption concurrent with orthodontic forces: the genetic influence

Root resorption is a pathological process of multifactorial origin related to the permanent loss of dental root structure in response to a mechanical, inflammatory, autoimmune or infectious stimulus. External apical root resorption (EARR) is a frequent clinical complication secondary to orthodontic tooth movement; apart from variables related to treatment, environmental factors and/or interindividual genetic variations can confer susceptibility or resistance to its occurrence. In this context, genetic predisposition has been described as an etiological factor, together with mechanical factors derived from orthodontic treatment. In recent years, international research groups have determined the degree of influence of some genetic biomarkers in defining increased/reduced susceptibility to postorthodontic EARR. The influences of the IL1 gene cluster (IL1B, IL1A, IL1RN, IL6), P2RX7, CASP1, OPG (TNFRSF11B), RANK (TNFRSF11A), Osteopontin (OPN), TNFα, the vitamin D receptor (TaqI), TNSALP and IRAK1 have been analyzed. The objective of the present review study was to compile and analyze the latest information about the genetic background predisposing to EARR during orthodontic treatment. Genetics-based studies along with other basic science research in the field might help to clarify the exact nature of EARR, the influence of genetic inheritance and possibly lead to the prevention or even eradication of this phenomenon during orthodontic treatment.

Genetic and clinical risk factors of root resorption associated with orthodontic treatment

INTRODUCTION

External apical root resorption (EARR) is a common complication in orthodontic treatment. Despite many studies on EARR, great controversies remain with regard to its risk factors. The objective of this study was to explore the relationship among sex, root movement, IL-1RN single nucleotide polymorphism (SNP) rs419598, IL-6 SNP rs1800796, and EARR associated with orthodontic treatment.

METHODS

Altogether 174 patients (with 174 maxillary left central incisors) were selected for this study. Cone-beam computed tomography was performed before the start of the treatment and at the end of the treatment. Cone-beam computed tomography data were used to reconstruct a 3-dimensional image of each tooth; the volume and the root resorption volume of each tooth were calculated. Three-dimensional matching was used to measure the amount of movement of each root. Genomic DNA was extracted from buccal swabs, and genotypes of SNP rs419598 and SNP rs1800796 of each subject were determined using TaqMan polymerase chain reaction genotyping (Applied Biosystems, Foster City, Calif). The data were analyzed with multiple linear regression analysis.

RESULTS

The statistical analysis indicated no relationship between sex, tooth movement amount, and IL-1RN SNP rs419598 with EARR. The IL-6 SNP rs1800796 GC was associated with EARR, and root resorption differed significantly between SNP rs1800796 GC and CC.

CONCLUSIONS

IL-6 SNP rs1800796 GC is a risk factor for EARR. The amount of root movement, IL-1RN SNP rs419598, and sex as risk factors for EARR need further study.