Pain and root resorption due to surgical interventions to accelerate tooth movement in orthodontics: A systematic review and meta-analysis.

BACKGROUND: There are several publications that show the efficacy of surgical interventions in accelerating the rate of tooth movement in orthodontics. Consequently, possible adverse effects must also be evaluated. OBJECTIVES: The aim of the present study was to compare the perception of pain and root resorption between orthodontic treatment with a surgical acceleration intervention vs. conventional orthodontic treatment. MATERIAL AND METHODS: An electronic search was conducted in the MEDLINE, Scopus, Web of Science (WoS), ScienceDirect, Cochrane Library, and Virtual Health Library (VHL) databases up to September 12, 2022. Randomized or non-randomized, controlled, parallel-arm or split-mouth clinical trials were included. Fixed-and random-effects meta-analyses were performed with regard to heterogeneity. The risk of bias (RoB) was assessed using the RoB 2.0 and ROBINS-I tools. RESULTS: A total of 1,395 articles were initially retrieved, 40 studies were finally included in the review and 15 studies were eligible for quantitative analysis. The meta-analysis showed a significant difference in pain perception between acceleration surgery vs. conventional orthodontics at 24 h (p = 0.040); however, this difference was not significant at 7 days (p = 0.080). Overall, the patients who underwent any acceleration procedure presented significantly less resorption as compared to those who were applied conventional treatment (p < 0.001). A similar significant difference was found in retraction movements (p < 0.001) and alignment movements (p = 0.030). CONCLUSIONS: In the first 24 h, surgical interventions for the acceleration of tooth movement produce a greater perception of pain as compared to conventional orthodontic treatment, but the perception is similar after 7 days. Acceleration surgery results in less root resorption - in alignment movements, and especially in retraction movements.

Influence of tube current and metal artifact reduction on the diagnosis of external cervical resorption in teeth adjacent to a dental implant in CBCT: an ex-vivo study.

OBJECTIVES: This ex-vivo study aimed to assess the influence of tube current (mA) and metal artifact reduction (MAR) on the diagnosis of early external cervical resorption (EECR) in cone-beam computed tomography (CBCT) in the presence of an adjacent dental implant. MATERIALS AND METHODS: Twenty-three single-rooted teeth were sectioned longitudinally and EECR was induced using a spherical drill and 5% nitric acid in 10 teeth. Each tooth was positioned in the socket of the lower right canine of a dry human mandible and CBCT scans were acquired using 90 kVp, voxel of 0.085 mm, field of view of 5 x 5 cm, and varying tube current (4, 8 or 12 mA), MAR (enabled or disabled) and implant conditions (with a zirconia implant in the socket of the lower right first premolar or without). Five oral radiologists evaluated the presence of EECR in a 5-point scale and the diagnostic values (area under the receiver operating characteristic curve - AUC, sensitivity, and specificity) were compared using multi-way Analysis of Variance (α = 0.05). Kappa test assessed intra-/inter-evaluator agreement. RESULTS: The tube current only influenced the AUC values in the presence of the implant and when MAR disabled; in this case, 8 mA showed lower values (p<0.007). MAR did not influence the diagnostic values (p>0.05). In general, the presence of an implant reduced the AUC values (p<0.0001); sensitivity values with 8 mA and MAR disabled, and specificity values with 4 mA and MAR enabled and 8 mA regardless MAR were also decreased (p<0.0001). CONCLUSIONS: Variations in tube current and MAR were unable to improve EECR detection, which was impaired by the presence of an adjacent implant. CLINICAL RELEVANCE: Increasing tube current or activating MAR tool does not improve EECR diagnosis, which is hampered by the artifacts generated by dental implants.

Root Regeneration with Photobiomodulation of an Upper Lateral Incisor Associated with Root Resorption Due to an Impacted Maxillary Canine: A Case Report.

Objective: To present a case report of maxillary lateral incisor root regeneration after severe root resorption, treated with photobiomodulation (PBM). Background: Impacted maxillary canines often come with the risk of maxillary lateral incisor root resorption, which is widely recognized as the predominant adverse effect in these situations. This progressive process of root resorption is currently irreversible, with no known way to reverse it. Materials and methods: A male patient was 14 years old. Radiographically it was observed that canine 23 is impacting against the root of 22 producing signs of root resorption and having a less than 1:1 crown-to-root ratio with mobility grade 1. From the beginning of the treatment, PBM-assisted orthodontics was proposed. To address the patient's dental concerns, the treatment plan outlined the extraction of the deciduous upper left canine tooth leaving the lateral as long as possible in the mouth. During each appointment, PBM was applied with a diode laser. The wavelength was 810 nm, Ap = 0.2 W, 4.4 J, 22 sec every 21 days, 13 applications in total (57.2J), with a 400 µm inactive surgical tip, in a scanning movement, 1 mm from the mucosa while moving following the vestibular surface of the upper left lateral and canine roots. Results: After 12 months, the 22 had root neoformation and complete closure of the apex with vitality. Conclusions: PBM with an 810 nm diode laser in this clinical case promoted root regeneration of an upper lateral incisor, with severe root resorption, owing to an impacted maxillary canine while still vital.

Alignment efficiency and three-dimensional assessment of root resorption after alignment with conventional and copper-nickel-titanium archwires: A randomized controlled trial.

OBJECTIVE: To compare alignment efficiency and root resorption between nickel-titanium (NiTi) and copper-nickel-titanium (CuNiTi) archwires after complete alignment in mandibular anterior region. METHODS: In this two-arm parallel single-blind randomized controlled trial, forty-four patients with Class I malocclusion with mandibular anterior crowding were recruited form orthodontic clinic of All India Institute of Medical Sciences (Jodhpur, India). Patients were randomly allocated into NiTi and CuNiTi groups, with a 1:1 allocation. Alignment was performed using 0.014-in, 0.016-in, 0.018-in, 0.019x0.025-in archwire sequence in the respective groups, which terminated in 0.019 x 0.025-in stainless-steel working archwire. The primary outcome was alignment efficiency, measured on study models from baseline (T0) to the first, second, third, fourth and fifth-month (T5). Secondary outcome was root resorption, measured from CBCT scans taken at T0 and T5. Mixed-factorial ANOVA was used to compare Little's Irregularity Index (LII). For assessing the proportion of patients with complete alignment at the end of each month, Kaplan-Meier survival curve was built and time to treatment completion was compared between groups using log rank test. Paired t-test was used to assess external apical root resorption (EARR) within groups, whereas independent t-test was used to evaluate LII and EARR between the groups. RESULTS: Twenty-two patients were recruited in each group. One patient was lost to follow-up in the CuNiTi group. No statistically significant differences were observed in alignment efficiency between the groups (p>0.05). Intergroup comparison revealed that the changes in root measurement in three-dimensions were not statistically significant (p>0.05), except for mandibular right central incisor, which showed increased resorption at root apex in NiTi group (p<0.01). CONCLUSION: The two alignment archwires showed similar rate of alignment at all time points. Root resorption measurement did not differ between the NiTi and CuNiTi groups, except for the mandibular right central incisor, which showed more resorption in NiTi group.

Prevalence and Characterization of External Cervical Resorption Using Cone Beam Computed Tomography.

INTRODUCTION: The aim of this study was to assess the prevalence of external cervical resorption (ECR) and characterize the cases of ECR using cone beam computed tomography (CBCT). METHODS: High-resolution CBCT scans of 6216 patients (2280 males and 3936 females), consecutively acquired during the period July 2021 to March 2022, were analyzed. Identified cases of ECR were characterized by 3 evaluators regarding lesion height, circumferential spread, portal of entry proximity to root canal, stage, location, and width. RESULTS: In a total of 38 patients and 40 teeth, ECR cases demonstrated an incidence of 0.61%. The median age of the patients was 39 years. Prevalence of ERC was 0.78% among males and 0.50% among females. The most affected teeth were the maxillary incisors and canines. The most frequent characteristics of the lesion were: extension up to the cervical third (47.5%), more than 270° circumferential spread (42.55%), probable pulpal involvement (57.5%), progressive stage (65%), supracrestal (52.1%) and mesial (34.7%) localization of >1 mm in size (52.1%) portals of entry. Cases with greater longitudinal involvement also showed greater circumferential progression (P = .008). There was no association between portal of entry location and bone crest or ECR reparative phase (P = .42). Inter-rater agreement ranged from good to very good. No association between portal of entry and ECR progression was observed. CONCLUSIONS: ECR showed low prevalence in the Brazilian population, affecting mostly anterior maxillary teeth of patients within a wide age range. CBCT allowed characterization of ECR lesions with good interobserver agreement.

Does leukocyte-platelet-rich fibrin (L-PRF) cause long term acceleration in the rate of canine retraction? A split-mouth, two-arm parallel group, randomized control trial.

OBJECTIVE: The present study was conducted to investigate the effects of leukocyte-platelet-rich fibrin (L-PRF) on the rate of maxillary canine retraction for a period of 5 months. METHODS: A split-mouth study was conducted on 16 subjects (9 males and 7 females; age range 17-25 years; mean age, 21.85±2.45 years) who required therapeutic extraction of bilateral maxillary first premolars. After the initial leveling and alignment, L-PRF plugs were placed in a randomly selected extraction socket (Experimental Group), and the other side served as a control (Control Group). Canine retraction was carried out by the activation of nickel-titanium (NiTi) closed-coil springs delivering 150 g of force. The rates of canine movement, canine rotation, tipping, root resorption, and molar movement were assessed at monthly intervals for five months (T0-T5). Pain, swelling and discomfort accompanying the procedure were assessed using a Likert scale. RESULTS: The study revealed a significant increase in the rate of canine movement on the experimental side in the first two months, and significant molar anchorage loss was observed only in the first month for control side. There were no statistically significant differences between the groups regarding canine rotation, tipping, probing depth, root resorption, and pain perception. CONCLUSIONS: The use of L-PRF plugs in extraction sockets considerably enhanced the rate of canine movement only in the first two months, and long-term efficacy was not observed in this study.

Orthodontic treatment in traumatized permanent teeth: a systematic review / Tratamento ortodôntico em dentes permanentes traumatizados: uma revisão sistemática

Objective: to analyze, through literature review, the available literature on orthodontic treatment in traumatized permanent teeth. Methods: A literature search was performed in electronic databases (PubMed and SciELO) using the descriptors [tooth injuries] OR [injuries, teeth] OR [injury, teeth] OR [teeth injury] OR [injuries, tooth] OR [injury, tooth] OR [tooth injury] OR [teeth injuries] AND [orthodontics]. Observational studies and clinical trials were included, narrative reviews, laboratory and in vitro studies, case reports and series as well as articles that presented abstracts written in languages other than Portuguese, English and Spanish were excluded from the study. Two reviewers considered the eligibility, the risk of bias of the analyzed data and the qualitative synthesis of the studies included. A total of 1,322 references were found and 4 articles met all inclusion criteria and were included in the qualitative analysis. Some consequences like pulp necrosis and root resorption have been highlighted and trauma severity should be considered when orthodontically intervening in previously traumatized teeth. Final considerations: The traumatized teeth can be orthodontically treated as long as the time of tissue reorganization is respected, and the pull and periodontal conditions are followed up.(AU)

Objetivos: analisar, por meio de revisão de literatura, a respeito do tratamento ortodôntico em dentes permanentes traumatizados. Metodologia: Uma pesquisa bibliográfica foi realizada em bancos de dados eletrônicos (PubMed e SciELO) usando os descritores [tooth injuries] ou [injuries, teeth] ou [injury, teeth] ou [teeth injury] ou [injuries, tooth] ou [injury, tooth] ou [tooth injury] ou [teeth injuries] e [orthodontics]. Foram incluídos estudos observacionais e ensaios clínicos, revisões narrativas, estudos laboratoriais e in vitro, relatos de casos e séries, bem como artigos que apresentassem resumos redigidos em idiomas diferentes do português, inglês e espanhol foram excluídos do estudo. Dois revisores consideraram a elegibilidade, o risco de viés dos dados analisados e a síntese qualitativa dos estudos incluídos. Foram encontradas 1.322 referências e 4 artigos atenderam a todos os critérios de inclusão e foram incluídos na análise qualitativa. Algumas consequências como necrose pulpar e reabsorção radicular têm sido destacadas e a gravidade do trauma deve ser considerada na intervenção ortodôntica em dentes previamente traumatizados. Considerações finais: Os estudos incluídos nesta revisão sugerem que dentes traumatizados podem ser tratados ortodônticamente desde que respeitado o tempo de reorganização tecidual e acompanhadas as condições pulpares e periodontais.(AU)

Impact of low intensity pulsed ultrasound on volumetric root resorption of maxillary incisors in patients treated with clear aligner therapy: A retrospective study.

OBJECTIVE: The aim of this study was to evaluate the volumetric root resorption in maxillary incisors following clear aligner therapy (CAT) with low-intensity pulsed ultrasound (LIPUS), and compare the results to CAT alone. MATERIAL AND METHODS: This retrospective study evaluated pretreatment (T0) and post-treatment (T1) cone-beam computed tomography imaging of 42 adult patients. Twenty-one patients (14 females, 7 males, mean age= 38.1±12.96 years) were treated using CAT with LIPUS device, whereas the other twenty-one matching controls patients (15 females, 6 males, mean age= 35.6±11.7 years) were treated using CAT alone. Images were analyzed and a segmentation protocol was applied on the maxillary incisors. Each segmented tooth volume was exported as a surface mesh in the Visualization Toolkit (VTK) file format. The VTK files for all maxillary incisors were coded and corresponding teeth volumes from T0 and T1 were superimposed. Clipping the crown of each tooth was done, then measurements of root volumes and differences between groups were performed. Changes in root volumes were assessed (p<0.05). RESULTS: Root loss was evident in all teeth in both groups, but was significantly increased in all maxillary incisors of the control group (p<0.001) and in upper left central incisor of LIPUS group (p=0.009). When both groups were compared, there was statistically significant minimal volumetric root loss in LIPUS group (3.50-7.32 mm3), when compared to control group (11.48-12.95 mm3) (p<0.05). CONCLUSION: LIPUS group showed less volumetric root resorption compared to control group during the studied treatment time using clear aligners.

External apical root resorption after orthodontic treatment: analysis in different chronological periods.

INTRODUCTION: External apical root resorption (EARR) is characterized by the definitive loss of tooth root structure, with a higher incidence in lateral and central maxillary incisors. OBJECTIVE: To identify, in different chronological periods, the incidence of EARR in the maxillary incisors (MI) of patients orthodontically treated with or without premolars extraction. METHODS: Periapical radiographs before and after orthodontic treatment of 1,304 MIs from 326 patients (205 women and 121 men) were evaluated for EARR, divided into five groups, according to the chronological period in which treatments were started: G90) from 1990 to 1994, G95) from 1995 to 1999, G00) from 2000 to 2004, G05) from 2005 to 2009, G10) from 2010 to 2015. The evaluation was performed in each group, in patients who underwent maxillary first premolars extraction and those who did not. For statistical analysis, Fisher's exact test was used, with a significance level of p < 0.05. The EARR was measured using the adapted Levander and Malmgren classification. RESULTS: Incidence of EARR was higher in MIs of patients treated with maxillary premolar extraction (p < 0.05) in two chronological periods (G00 and G10), also being influenced by orthodontic treatments with longer duration, and due to possible individual genetic factors. CONCLUSION: Even with the limitations of a retrospective study, the lack of a defined EARR pattern in the MIs at different chronological periods was larger in the experimental group, due to the sum of factors such as premolars extraction, prolonged orthodontic treatment, possible genetic characteristics, and root shape, without the influence of the sex and age.

External Apical Root Resorption in Orthodontic Patients Who Practice Combat Sports: A Case-Control Observational Pilot Study.

Orthodontic treatment could lead to undesirable effects such as external apical root resorption (EARR). Moreover, trauma to both the face and teeth can predispose to EARR. On the other hand, the practice of combat sports results in increased maxillofacial injuries. Consequently, our objective was to determine if there is a statistically significant difference in the EARR of the patients undergoing fixed orthodontic treatment who practice combat sports and controls. Our null hypothesis was that there is no difference in the EARR between patients undergoing orthodontic treatment who practice combat sports and the patients under the same treatment that do not practice combat sports. An observational, descriptive, and prospective case-control pilot study was designed. The exposed group consisted of patients that practice combat sports. Whereas the control group was conformed of patients that do not practice combat sports without a previous history of facial trauma and without face trauma during the orthodontic treatment. EARR of the maxillary and mandibular anterior teeth was measured using cone-beam computed tomography (CBCT). The CBCT scans were obtained from all patients prior to the beginning of the orthodontic treatment and 1 year later. At the end of the follow-up for the maxillary right central and lateral incisors of the exposed group, the EARR was significantly higher than the homologous teeth of the control group (p < 0.05). As a consequence, the patients treated orthodontically who practice combat sports could be more susceptible to EARR.

Root resorption factors associated with orthodontic treatment with fixed appliances: A systematic review and meta-analysis.

External apical root resorption (EARR) is a serious complication that should be avoided during orthodontic treatment; this pathology depends on multiple factors. Data from clinical studies should be assessed to determine the influence these factors have on the development of EARR. This systematic review aims to compare EARR produced by different factors (orthodontic systems, dental trauma, and dental vitality). The protocol was registered on the PROSPERO database. The search was performed on 5 databases. Accepted study designs included randomized controlled trials, nonrandomized clinical trials, and observational studies. Full-text articles from clinical studies of EARR associated with orthodontic treatment in English, Spanish, or Portuguese with no publication date restrictions were selected. Data from the studies, such as age, population, study groups, and outcome measures, were recorded. Multiple meta-analyses were performed with data from the included studies. Evidence suggests that EARR induced by orthodontic treatment is similar, regardless of the technique used. Evidence of the effect of previous dental trauma on EARR during orthodontic treatment is limited. There is less EARR associated with orthodontic treatment in endodontically treated teeth than in vital teeth. These conclusions should be considered with caution due to the low certainty of the evidence.

External root resorption evaluated by CBCT 3D models superimposition.

INTRODUCTION: The literature reports the association of external root resorption (ERR) with orthodontic movement. In cases of premolars extractions, orthodontic movement of anterior teeth is usually quite expressive, which are precisely the most susceptible teeth to suffer from ERR. OBJECTIVE: The aim of this study was to assess the root morphology of maxillary canines and incisors in patients submitted to four premolar extraction and orthodontic retraction of the anterior teeth, by means of 3D surface models superimposition and mapping. METHODS: The sample consisted of six adult patients, five female and one male, with a mean age of 23.5 ± 6.5 years, who underwent orthodontic treatment. All patients presented bimaxillary dental protrusion, with indication of maxillary and mandibular first premolar extractions, followed by the retraction of anterior teeth and space closure. Cone beam CT scans were performed before the beginning of the treatment (T0) and right after space closure (T1). 3D models were built at both times and superimposed to identify the root changes for the given period. RESULTS: All average differences were close to zero and, even when evaluating the extreme values, the observed changes were always smaller than the accuracy of the CBCT. CONCLUSION: A mild resorption trend was observed, although it was not clinically significant, with values lower than the tomography accuracy.

Canines and inflammatory external apical resorption in healthy maxillary lateral incisors due to occlusal trauma: when to detect the position of maxillary canines, to prevent it?

JUSTIFICATION: Canines represent corners in the dental arch, and are important features in facial esthetics, as they support the upper lip, wing of the nose, and influence the nasolabial fold and the appearance of facial aging. In the laterality movements, the canines guidance coordinate the opening and closing of the teeth, saving the TMJ from sudden movements. DISCUSSION: As a result of the lack of eruption or the inadequate positioning of the maxillary canine, the loss of the laterality guide may occur, which will then occur in the maxillary lateral incisor, inducing lesions of "occlusal trauma", such as inflammatory root resorption. Likewise, without well positioned canines, there may be premature aging and change in facial esthetics. CONCLUSION: In order to avoid problems with eruption and positioning of the maxillary canines, early diagnosis is made by analyzing their position and their relationship with the other teeth, and in the three-dimensional context of the maxilla, between 8-10 years of age. Preventive measures can create bone space and direction so that the maxillary canines can occupy their position in the dental arch.

The two extremes of physiological tooth resorption in primary tooth with or without the permanent successor tooth.

INTRODUCTION: Assessment of two radiographic images reveals two distinct, extreme situations of physiological tooth resorption, characteristic of primary teeth with or without permanent successor, due to partial anodontia. DISCUSSION: In all primary teeth, rhizolysis begins after the completion of formation, thanks to the apoptosis of their cells. When apoptosis induced by cementoblasts has denuded the root of these cells, the process of rhizolysis inevitably begins: This will be accelerated by mediators arising from the pericoronal follicle. When there is no permanent successor due to partial anodontia, rhizolysis occurs extremely slowly, and months later, without the epithelial rests of Malassez that were dead due to apoptosis, alveolodental ankylosis becomes established, and the tooth will gradually be replaced by bone, still within a physiological context. CONCLUSION: Rhizolysis and physiological tooth resorption may occur rapidly or slowly, early or late, and this depends on the presence of the permanent tooth, or its absence due to partial anodontia.

The correlation between external apical root resorption and electric pulp test responses: a prospective clinical trial.

OBJECTIVE: The current study investigated the correlation between pulpal sensitivity to the electric pulp tester (EPT) and external apical root resorption (EARR) in four types of maxillary anterior teeth of fixed orthodontic treatment patients. METHODS: In this prospective cohort study, 232 anterior teeth of 58 patients (mean age 18.96 ± 6.13 years) treated with fixed orthodontic treatment were examined. The EPT readings were recorded at twelve time points immediately before archwire insertion. Root resorption of four maxillary incisors were measured by means of parallel periapical radiographs at three time intervals (six months interval from the start) through design-to-purpose software to optimize data collection. A multiple linear regression model and Pearson correlation coefficient were used to assess the association of EPT values and observed EARR (p< 0.05). RESULTS: The highest level of EPT measurement was recorded at initial visit, and then there was a decreasing trend in EPT level during treatment for the next six and twelve months. There was another increasing trend after six months till the finishing time of the treatment. There was a significant correlation between changes in root length and time of recording the root length (p< 0.001). There was significant positive correlation between changes in EPT level and amount of observed root resorption (p< 0.001). CONCLUSION: The relative decrease in electric pulp test level could be a diagnostic sign of root resorption during orthodontic treatment. Further studies with longer follow up are needed to confirm the current results.

Allergies/asthma and root resorption: a systematic review.

BACKGROUND: This review synthesizes the available evidence about the predisposition of individuals with asthma or allergies to orthodontically induced inflammatory root resorption (OIIRR) and possible factors related to root resorption that were investigated in the included studies, such as the type of malocclusion, duration of orthodontic treatment, and tooth units. MATERIAL AND METHODS: Six electronic databases and partial gray literature were searched without date or language restrictions until September 2020. Prospective and retrospective observational cohort and case-control studies were included. The risk of bias (RoB) was assessed using the checklists from the Joanna Briggs Institute and the certainty of the evidence using the GRADE tool. To complement the case-control studies, the odds ratio (OR) of the individuals with allergies/asthma to develop root resorption was calculated. RESULTS: Six studies were included. One study with low RoB, one with moderate, and one with high RoB stated that allergic patients did not report a greater chance of developing OIIRR (OR = 1.17 to 2.10, p = 0.1 to 1), while only one study with low RoB reported that individuals with allergies tend to develop root resorption (OR = 2.4, 95% CI = 1.08-5.37). Three studies with low RoB and one with moderate showed no significant association between asthma and OIIRR (OR = 1.05 to 3.42, p = 0.12 to 0.94). No association was identified between the type of malocclusion and the degree of OIIRR. Uniradicular dental units and a prolonged treatment time seem to be associated with an increased risk of resorption. The certainty of the evidence was considered low for both exposure factors. CONCLUSION: Evidence with a low level of certainty indicates that individuals with allergies or asthma are not more predisposed to OIIRR. Uniradicular teeth and long-term orthodontic treatments are associated with a higher risk of OIIRR. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42020188463.

Pulp healing in immature replanted permanent teeth: A competing risk analysis.

BACKGROUND/AIM: Tooth displacement during avulsion causes total rupture of the pulp's neurovascular supply. Revascularization and pulp healing may occur in immature teeth, which gives rise to the recommendation that root canal treatment may not be required. The aim of this study was to evaluate the prognostic factors for the pulp's response after replantation of young permanent teeth. METHODS: Records from 117 patients with 133 replanted permanent immature teeth were reviewed, and pulp outcomes were classified as healing (hard tissue deposition on the dentinal walls followed by narrowing of the pulp lumen or ingrowth of bone-like tissue inside the pulp canal) or non-healing (pulp necrosis with infection). The effect of clinical and demographic co-variates on the hazards of both outcomes was assessed performing a competing risk model. RESULTS: Pulp necrosis with infection was diagnosed in 78.2% of the teeth, and healing was observed in 12.8% of the teeth. A total of 12 teeth (9.0%) were censored due to prophylactic removal of the pulp or severe external root resorption caused by eruption of adjacent canines. The cs-Cox model demonstrated that the hazards of pulp healing increased in teeth with extra-alveolar periods <15 min (csHR: 7.83, 95% CI 1.76-34.80, p = .01), while the hazards of pulp necrosis with infection decreased (csHR: 0.31, 95% CI: 0.10-0.92, p = .04). Teeth replanted with Moorrees' stages 4 and 5 of root development had higher hazards of pulp necrosis with infection than teeth with stage 2 of root development (csHR: 2.23, 95% CI 1.11-4.50, p = .03; csHR: 2.89, 95% CI: 1.40-5.95; p = .01). CONCLUSIONS: Pulp healing rarely occurred after replantation of young permanent teeth being associated with short extra-alveolar periods <15 min. Early stages of root development decreased the hazards of pulp necrosis with infection.

Effect of orthodontic forces on root length of immature mandibular second premolars: a split-mouth randomized clinical trial.

OBJECTIVE: To assess the effect of orthodontic forces on changes in root length of immature mandibular second premolars. METHODS: Sixty-four mandibular second premolars (MSP) with immature apices (left and right sides) of 32 patients aged between 10 and 13 years were evaluated. Orthodontic treatment was started after obtaining periapical radiographs (T1) from the MSPs of each patient. Brackets were bonded, except the ones of MSPs (left or right by random as control MSP, and the other side as test MSP). After 9-12 months, a second periapical radiograph (T2) was obtained from the MSPs of each patient. Then, brackets were bonded to the control MSPs, which were not bonded before. After 18 ± 3 months, a third periapical radiograph (T3) was obtained. Changes in root length were evaluated by using a new formula. The test and control MSPs at T1, T2 and T3 were compared using repeated measures ANOVA and parametric tests. P-value smaller than 0.05 was statistically significant. RESULTS: There was no significant difference between the test and control groups in the mean root length of MSP at T1 (p= 0.48) and T3 (p= 0.078). The root length at T2 (p= 0.001) was significantly different between test and control MSPs, and the test group showed longer root length than the control group. CONCLUSIONS: Orthodontic force applied for leveling and alignment of immature MSPs may not have destructive effects on the roots, and may accelerates root formation in short-term. Normal root length was achieved at the end of root development.

The correlation between external apical root resorption and electric pulp test responses: a prospective clinical trial

ABSTRACT Objective: The current study investigated the correlation between pulpal sensitivity to the electric pulp tester (EPT) and external apical root resorption (EARR) in four types of maxillary anterior teeth of fixed orthodontic treatment patients. Methods: In this prospective cohort study, 232 anterior teeth of 58 patients (mean age 18.96 ± 6.13 years) treated with fixed orthodontic treatment were examined. The EPT readings were recorded at twelve time points immediately before archwire insertion. Root resorption of four maxillary incisors were measured by means of parallel periapical radiographs at three time intervals (six months interval from the start) through design-to-purpose software to optimize data collection. A multiple linear regression model and Pearson correlation coefficient were used to assess the association of EPT values and observed EARR (p< 0.05). Results: The highest level of EPT measurement was recorded at initial visit, and then there was a decreasing trend in EPT level during treatment for the next six and twelve months. There was another increasing trend after six months till the finishing time of the treatment. There was a significant correlation between changes in root length and time of recording the root length (p< 0.001). There was significant positive correlation between changes in EPT level and amount of observed root resorption (p< 0.001). Conclusion: The relative decrease in electric pulp test level could be a diagnostic sign of root resorption during orthodontic treatment. Further studies with longer follow up are needed to confirm the current results.

RESUMO Objetivo: O presente estudo investigou a correlação entre a sensibilidade pulpar ao teste pulpar elétrico (TPE) e a reabsorção radicular apical externa (RRAE) nos quatro dentes anteriores superiores de pacientes em tratamento ortodôntico com aparelho fixo. Métodos: Nesse estudo de coorte prospectivo, foram avaliados 232 dentes anteriores de 58 pacientes (idade média 18,96 ± 6,13 anos) tratados com aparelho ortodôntico fixo. As leituras do TPE foram registradas em doze tempos de avaliação, imediatamente antes da inserção dos arcos. As reabsorções radiculares dos quatro incisivos superiores foram aferidas por meio da média das radiografias periapicais, em três intervalos de tempo (em intervalos de seis meses desde o início) por um software desenvolvido para essa finalidade, com o intuito de otimizar a coleta de dados. Para aferir a associação entre os valores de TPE e as RRAE observadas (p< 0,05), foram utilizados o modelo de regressão linear múltiplo e o coeficiente de correlação de Pearson. Resultados: O nível mais alto das medidas do TPE foi registrado na primeira visita e, daí em diante, houve uma tendência de diminuição no nível do TPE durante o tratamento, nos seis a doze meses seguintes. Houve, também, outra tendência de aumento após os seis meses até o término do tratamento, além de uma correlação significativa entre as mudanças no comprimento radicular e o tempo de registro do comprimento radicular (p< 0,001), bem como uma correlação positiva significativa entre as mudanças no nível do TPE e a quantidade de reabsorção radicular observada (p< 0,001). Conclusão: Uma diminuição relativa no nível de sensibilidade ao teste pulpar elétrico pode ser um sinal diagnóstico de reabsorção radicular durante o tratamento ortodôntico. Estudos futuros com acompanhamentos mais longos são necessários para confirmar os presentes resultados.

Alteraciones dentarias en piezas sometidas a fuerzas de ortodoncia con técnica de Arco Recto / Dental alterations in pieces subjected to orthodontic forces with the straight wire technique

El objetivo fue evaluar radiográficamente las alteraciones dentarias en piezas sometidas a fuerzas ortodóncicas. Se analizaron 2871 piezas dentarias por observación radiográfica pre y post tratamiento. Variables registradas: sexo, edad, tipo de alteración, pieza dentaria y grado de reabsorción. Se calcularon intervalos de confianza 95% por método score de Wilson. Se utilizó prueba de bondad de ajuste Chi cuadrado, comparando frecuencias observadas con frecuencias esperadas bajo independencia. Se utilizó prueba de diferencia de proporciones, estadístico de Fisher y prueba Chi-cuadrado de asociación. Se concluyó que las alteraciones dentarias post tratamiento de ortodoncia son frecuentes y se originan en factores biológicos y mecánicos. La mayor tasa de prevalencia son las reabsorciones radiculares. Es responsabilidad del ortodoncista conocer todos los factores de riesgo con el fin de prevenirlas o detenerlas a tiempo (AU)