Circadian clock genes REV-ERBα regulates the secretion of IL-1ß in deciduous tooth pulp stem cells by regulating autophagy in the process of physiological root resorption of deciduous teeth.

Physiological root resorption is a common occurrence during the development of deciduous teeth in children. Previous research has shown that the regulation of the inflammatory microenvironment through autophagy in DDPSCs is a significant factor in this process. However, it remains unclear why there are variations in the autophagic status of DDPSCs at different stages of physiological root resorption. To address this gap in knowledge, this study examines the relationship between the circadian clock of DDPSCs, the autophagic status, and the periodicity of masticatory behavior. Samples were collected from deciduous teeth at various stages of physiological root resorption, and DDPSCs were isolated and cultured for analysis. The results indicate that the circadian rhythm of important autophagy genes, such as Beclin-1 and LC3, and the clock gene REV-ERBα in DDPSCs, disappears under mechanical stress. Additionally, the study found that REV-ERBα can regulate Beclin-1 and LC3. Evidence suggests that mechanical stress is a trigger for the regulation of autophagy via REV-ERBα. Overall, this study highlights the importance of mechanical stress in regulating autophagy of DDPSCs via REV-ERBα, which affects the formation of the inflammatory microenvironment and plays a critical role in physiological root resorption in deciduous teeth.

Effect of low-intensity pulsed ultrasound on the mineralization of force-treated cementoblasts and orthodontically induced inflammatory root resorption via the Lamin A/C-Yes associated protein axis.

AIMS: Orthodontic treatment commonly results in orthodontically induced inflammatory root resorption (OIIRR). This condition arises from excessive orthodontic force, which triggerslocal inflammatory responses and impedes cementoblasts' mineralization capacity. Low-intensity pulsed ultrasound (LIPUS) shows potential in reducing OIIRR. However, the precise mechanisms through which LIPUS reduces OIIRR remain unclear. This study aimed to explore the effects and mechanisms of LIPUS on the mineralization of force-treated cementoblasts and its impact on OIIRR. METHODS: We established a rat OIIRR model and locally administered LIPUS stimulation for 7 and 14 days. We analyzed root resorption volume, osteoclast differentiation, and the expression of osteocalcin and yes-associated protein 1 (YAP1) using micro-computed tomography (micro-CT), hematoxylin and eosin, tartrate-resistant acid phosphatase, immunofluorescence and immunohistochemistry staining. In vitro, we applied compressive force and LIPUS to the immortalized mouse cementoblasts (OCCM30). We assessed mineralization using alkaline phosphatase (ALP) staining, alizarin red staining, real-time quantitative polymerase chain reaction, Western blotting and immunofluorescence staining. RESULTS: In rats, LIPUS reduced OIIRR, as evidenced by micro-CT analysis and histological staining. In vitro, LIPUS enhanced mineralization of force-treated OCCM30 cells, as indicated by ALP and alizarin red staining, upregulated mRNA expression of mineralization-related genes, and increased protein expression of mineralization markers. Mechanistically, LIPUS activated YAP1 signaling via the cytoskeleton-Lamin A/C pathway, supported by immunofluorescence and Western blot analysis. CONCLUSION: This study demonstrates that LIPUS promotes mineralization in force-treated cementoblasts and reduces OIIRR by activating YAP1 through the cytoskeletal-Lamin A/C signaling pathway. These findings provide fresh insights into how LIPUS benefits orthodontic treatment and suggest potential strategies for preventing and treating OIIRR.

NLRP3-mediated periodontal ligament cell pyroptosis promotes root resorption.

AIM: To investigate the mechanisms by which periodontal ligament cells (PDLCs) convert biomechanical stimulation into inflammatory microenvironment inducing root resorption (RR). MATERIALS AND METHODS: RNA sequencing was employed to explore mechanisms in force-inflammatory signal transduction. Then resorption volume, odontoclastic activity, PDLC pyroptotic ratio and NOD-like receptor protein 3 (NLRP3)-mediated pyroptosis pathway activation were analysed under force and pyroptosis inhibition. Further osteoclast formation, macrophage number and transwell polarization demonstrated the effects of PDLC pyroptosis on osteoclastogenesis and M1 polarization. RESULTS: RNA sequencing revealed that NLRP3-mediated PDLC pyroptosis induced by Toll-like receptor 4 (TLR4)/nuclear factor kappa B (NFκB)/NLRP3 pathway may be involved in mechano-inflammatory signal transduction. PDLC pyroptosis under force and the expression of NLRP3-mediated pyroptosis pathway in force-enhanced PDLCs were significantly increased, both in vivo and in vitro. MCC950 administration was sufficient to reduce PDLC pyroptosis and alleviate RR, odontoclast formation and M1 polarization in vivo. Further in vitro exploration showed that MCC950 treatment reduced PDLC force-promoted pyroptosis and blocked NLRP3-mediated pyroptosis pathway. Moreover, by treating THP-1 with force-pretreated PDLCs or supernatants, NLRP3-mediated PDLC pyroptotic released products induced osteoclast formation and M1 polarization. CONCLUSIONS: NLRP3-mediated PDLC pyroptosis promotes RR. PDLCs transmit excessive force into inflammation signals through TLR4/NFκB/NLRP3 pathway, inducing PDLC pyroptosis, which directly promotes odontoclast formation and subsequent RR or promotes M1 polarization to indirectly trigger odontoclastogenesis and RR.

Hypoxic dental pulp stem cells-released succinate promotes osteoclastogenesis and root resorption.

Introduction: Clinical studies have shown that endodontically-treated nonvital teeth exhibit less root resorption during orthodontic tooth movement. The purpose of this study was to explore whether hypoxic dental pulp stem cells (DPSCs) can promote osteoclastogenesis in orthodontically induced inflammatory root resorption (OIIRR). Methods: Succinate in the supernatant of DPSCs under normal and hypoxic conditions was measured by a succinic acid assay kit. The culture supernatant of hypoxia-treated DPSCs was used as conditioned medium (Hypo-CM). Bone marrow-derived macrophages (BMDMs) from succinate receptor 1 (SUCNR1)-knockout or wild-type mice were cultured with conditioned medium (CM), exogenous succinate or a specific inhibitor of SUCNR1 (4c). Tartrate-resistant acid phosphatase (TRAP) staining, Transwell assays, qPCR, Western blotting, and resorption assays were used to evaluate osteoclastogenesis-related changes. Results: The concentration of succinate reached a maximal concentration at 6 h in the supernatant of hypoxia-treated DPSCs. Hypo-CM-treated macrophages were polarized to M1 proinflammatory macrophages. Hypo-CM treatment significantly increased the formation and differentiation of osteoclasts and increased the expression of osteoclastogenesis-related genes, and this effect was inhibited by the specific succinate inhibitor 4c. Succinate promoted chemotaxis and polarization of M1-type macrophages with increased expression of osteoclast generation-related genes. SUCNR1 knockout decreased macrophage migration, M1 macrophage polarization, differentiation and maturation of osteoclasts, as shown by TRAP and NFATc1 expression and cementum resorption. Conclusions: Hypoxic DPSC-derived succinate may promote osteoclast differentiation and root resorption. The regulation of the succinate-SUCNR1 axis may contribute to the reduction in the OIIRR.

Efficacy of maxillary molar intrusion and quantification of related external apical root resorption - A comparison of two approaches.

OBJECTIVE: This retrospective single-centre study aimed to compare the efficacy of maxillary second molar intrusion with two different approaches, miniscrew-assisted molar intrusion and traditional segmental archwire intrusion, and to compare orthodontically induced external apical root resorption (OIERR) during intrusion between two groups via cone beam computed tomography (CBCT). MATERIALS AND METHODS: A total of 40 adult patients (33.6 ± 10.3 years old) with supraerupted maxillary second molars due to the loss of antagonistic teeth were recruited, with 20 patients in each group. A segmental archwire with adjacent teeth as an anchorage was used in the control group, and 60-100 g of intrusive force was applied by using miniscrews in the experimental group to intrude the overerupted molars. Full-volume CBCT was performed before and after intrusion, and the amount of intrusion and extent of OIERR of the overerupted molars were compared between the two groups. RESULTS: Supraerupted maxillary second molars could be successfully intruded in an average of 5 months. There was more intrusive movement of the buccal and palatal cusps in the mininscrew group than that in the segmental archwire group (P < .05). The intrusive amount of palatal cusp was 3.67 ± 1.13 mm in the miniscrew group and 2.38 ± 0.74 mm in the segmental archwire group. More palatal OIERR was observed in the miniscrew group (30.3 ± 11.6 mm3) than in the segmental archwire group (21.0 ± 8.66 mm3) (P = .0063). There was no significant difference in OIERR between the two groups for mesial and distal buccal roots (P > .05). CONCLUSION: Miniscrews help effectively with supraerupted maxillary second molar intrusion, especially for palatal cusps. There was more OIERR in the palatal root when using miniscrews compared to the segmental archwire approach.

Preventive and reparative effects of low-level laser therapy on orthodontically induced inflammatory root resorption-An animal study.

BACKGROUND: Orthodontically induced inflammatory root resorption (OIIRR) is one of the most important side effects of orthodontic treatment. Low-level laser therapy (LLLT) is a useful way to reduce the orthodontic treatment duration and may have some effect on preventing and repairing OIIRR. However, the specific effects of LLLT on OIIRR remain unknown. OBJECTIVE: Our research aimed to evaluate the Dentin Sialophosphoprotein (DSPP) expression level and root resorption volume during treatment and retention to explore the role of LLLT in preventing and repairing OIIRR. METHODS: Thirty-seven 6-week-old male Sprague-Dawley rats were selected to establish an OIIRR model; the rats were divided into Group B (blank), Group F (force), Group F(LLLT) (force and LLLT), Group F+R (force and retention) and Group F+R(LLLT) (force, retention and LLLT). The root resorption volume of the distal buccal root and mesial root in the maxillary left first molar was calculated by micro-CT, and the DSPP expression level on the compression side of the periodontal ligament was analysed by immunohistochemical staining. RESULTS: The resorption volume in Group F was greater than that in Group F(LLLT). For the mesial root, the volume in Group F was greater than that in Groups F+R and F+R(LLLT). For the distal buccal root, the volume in Groups F and F+R was greater than that in Group F+R(LLLT). The DSPP level in Group F(LLLT) was greater than that in Group F and there was no difference between Groups F+R and F+R(LLLT). CONCLUSIONS: LLLT has a certain preventive effect and a limited reparative effect on OIIRR in rats.

Apical incisor root resorption due to ectopic maxillary canine eruption: Association with time of diagnosis and type of intervention in a retrospective population-based cohort study.

OBJECTIVES: The primary aim was to study upper incisor severe apical root resorption (RR) related to ectopic canine eruption and its association with timing of diagnosis and type of intervention conducted. The secondary aim was to correlate resorption with other dental anomalies. MATERIALS AND METHODS: Digital journals and radiographic material of all ectopic maxillary canines registered in 2012 in the regional public paediatric dental clinics in the Council of Aarhus were inspected retrospectively. Data related to 10 variables were retrieved. Post-treatment radiographs were used for evaluation of incisor RR. RESULTS: A total of 260 ectopic maxillary canines were diagnosed in 2012. The majority were found in the 9-13-year-old age group (0.8% prevalence within the total population). In all, 244 canines were assessed for eligibility and 181 had adequate final radiographs for evaluation of RR. Among ectopic maxillary canines, 9.4% caused severe incisor RR to neighbouring teeth. Timely palpation for canine eruption significantly reduced the odds for upper incisor resorption by 80%. Multiple regression showed that when the permanent canine cannot be palpated and the deciduous has been extracted, delaying the first X-rays was associated with a 38% odds ratio increase for RR for each year of delay after the age of 10 years. No significant associations were found between incisor RR and intervention conducted or other dental anomalies. CONCLUSION: Palpation of erupting maxillary canines is crucial for timely diagnosis of ectopic eruption and initiation of treatment to avoid RR. If the canine cannot be palpated at 10 years of age, radiographic examination is highly recommendable.

Effects of isotretinoin on tooth movement, orthodontically induced and non-orthodontic root resorption: A micro-CT and study.

OBJECTIVES: This study aims to investigate whether cumulative dose-dependent isotretinoin (Roaccutane®) could affect orthodontic tooth movement (OTM) and root resorption. MATERIALS AND METHODS: Ninety male Wistar Albino rats were divided into 4 groups. While, the control (SALINE), solvent (SOYBEAN) and orthodontic drug (ISOTM) groups underwent orthodontic force, the non-orthodontic drug group (ISO) did not. The rats were administrated saline, soybean oil (SBO) and isotretinoin diluted in SBO (ISOTM, ISO) for 30 days, respectively. Six rats were euthanized in each orthodontic group. Fifty grams of orthodontic force was applied to the remaining rats' first molars using the incisors as anchorage. Six more rats in each group were euthanized on the 7th, 14th and 21st days of the force application. In the ISO group, six rats were euthanized on the 37th, 44th and 51st days of administration. Six rats that were euthanized for ISOTM on the 30th day were also used for ISO to reduce the number of rats used. Micro-computed tomography (micro-CT) and histological analysis were performed. RESULTS: Independent of orthodontic force, isotretinoin caused root resorption in the apical region. However, there was no statistically significant influence of isotretinoin on OTM and orthodontically induced root resorption (OIRR). CONCLUSIONS: Despite the lack of strong evidence supporting the orthodontically induced resorptive effect of isotretinoin, this study provided findings regarding the resorptive effects of isotretinoin on non-orthodontic root resorption. Therefore, the present results underscore the importance of close monitoring during orthodontic treatment to mitigate potential root resorption in patients who use isotretinoin because of acne complaints.

Three-dimensional volumetric evaluation of root resorption in maxillary anteriors following en-masse retraction with varying force vectors - a randomized control trial.

BACKGROUND: Root resorption in orthodontics is associated with direction and magnitude of force application as primary etiological factors. Well-controlled trials that utilize three-dimensional segmentation to detect volumetric changes in tooth structure are required to assess the quantitative nature of root resorption. OBJECTIVE: To assess the severity of root resorption (RR) during retraction of maxillary anteriors with three different force vectors (with and without skeletal anchorage) via cone-beam computed tomography (CBCT) superimpositions. TRIAL DESIGN: Three-arm parallel randomized clinical trial (RCT). MATERIALS AND METHODS: Forty-two (16 males, 26 females) patients, (17-28 years), in permanent dentition with bimaxillary protrusion were randomly allocated to three groups of 14 patients each using block randomization (1:1:1 ratio) and allocation concealment. En-masse anterior retraction post first premolar extractions was carried out with modified force vectors in the three groups based on anchorage type [Molar, Mini-implant and Infrazygomatic crest (IZC) bone screws]. Volumetric root loss and linear dimensional changes were blindly assessed on initial (T0) and final (T1, end of space closure) CBCT scans. Normality distribution of values was done using Shapiro-Wilk's test. ANOVA and Post-hoc Tukey HSD test were done to compare measurements between groups at significance levels (P < .05). RESULTS: Forty patients were analysed (14, 14, and 12 in three groups). Significant volumetric loss was noted in all groups. Central incisors demonstrated a significant reduction in IZC group (81.5 ± 21.1 mm3 ) compared to conventional (50.1 ± 26.5 mm3 ) and mini-implant groups (76.1 ± 27.6 mm3 ). Canines demonstrated a significant reduction in mini-implant group (108.9 ± 33.9 mm3 ) compared to conventional (68.8 ± 42.5 mm3 ) and IZC groups (103.1 ± 29.1 mm3 ). Regarding linear parameters, central incisors and canines revealed significant root length reduction in both skeletal anchorage groups. Lateral incisors showed no significant changes between groups. CONCLUSIONS: Intrusive force vectors generated during skeletally anchored retraction can predispose anteriors to an increased risk of resorption. Greater loss of root volume was noted in the centrals and canines when retracted with skeletal anchorage. LIMITATIONS: Small sample size and variations during CBCT acquisition. HARMS: Low-dose CBCT scans were taken at T0 and T1 treatment intervals.

The role of infection in signalling root resorption: A narrative review.

BACKGROUND: Root resorption consists of complex, multistep processes that involve cell signalling caused by inflammation and stromal cells, which promotes the secretion of receptor activator of nuclear factor κB ligand/ macrophage-colony stimulating factor (RANKL/M-CSF) resulting in a resorptive process. OBJECTIVE: The aim of this narrative review was to analyse the literature related to root resorption resulting from microbial infection and to comparing it with non-microbial infection. METHODS: An electronic literature search was performed using the PubMed database and applying keywords of articles published in English. Eligible papers were reviewed to reveal the descriptions of bone and root resorption processes. The abstracts were searched manually to identify articles about infection-stimulating bone and root resorption. RESULTS: Three main types of root resorption were identified, two associated with primary bacterial infection and one secondary to bacterial infection. These include external inflammatory resorption, internal inflammatory resorption and external cervical (invasive) resorption. DISCUSSION: The magnitude of cytokine involvement that promotes resorption and M-CSF/RANKL production depends on multiple factors, including pathogen virulence, site of infection and host genetic factors that activate the inflammation at the infection site. Two mechanisms activate the resorption mechanisms-the canonical and non-canonical pathways that can activate clastic cells independently of the RANKL/RANK canonical pathways. CONCLUSIONS: Two pathways of root resorption co-exist in the body. When resorption is caused by infection, chronic inflammation due to bacterial infection prolongs the secretions of pro-inflammatory cytokines that intensify root and bone resorption. The second pathway is bacterial independent of the non-infection root resorption that is part of the wound healing process, which is limited in time due to its innate ability.

Evaluation of the efficacy of different irrigation activation techniques in removing of calcium hydroxide on teeth with the simulated internal root resorption cavity: a confocal laser scanning microscope analysis.

The aim of this study is to evaluate the effect of different irrigation activation methods on root canal sealer penetration in teeth with simulated internal root resorption (IRR) and calcium hydroxide (CH) applied using a confocal laser scanning microscope (CLSM). 60 incisors with a single root and a single canal were included in the study. IRR cavities were created in the middle third of the root canal, and CH was placed. The samples were randomly divided into 4 groups (n = 15) according to the irrigation activation method to be tested: standard needle irrigation (SNI), sonic activation (EDDY), photon-induced photoacoustic flow (PIPS), and shock wave enhanced emission photoacoustic flow (SWEEPS). After irrigation activation applications, the root canals were obturated. Sections of 1.0 ± 0.1 mm were taken from the apical, middle, and coronal regions of each sample. The penetration area (µm2) and maximum penetration depth (µm) of the root canal sealer were examined by CLSM and analyzed using ImageJ software. Statistical analysis was performed with a one-way ANOVA and post-hoc Tukey test at the P < 0.05 significance level. Among all irrigation activation methods tested, both the penetration area and maximum penetration depth of the root canal sealer were greater in the coronal region than in the apical region (p < 0.05). In the IRR region, there was no difference in terms of maximum penetration depth between PIPS and SWEEPS (p > 0.05), it was highest in SWEEPS (p < 0.05). PIPS and SWEEPS were better than other irrigation activation methods in the penetration of root canal sealer in the resorption areas of teeth with IRR.

Histological effects of photobiomodulation on delayed tooth replantation: a systematic review.

This systematic review evaluated preclinical studies to assess whether PBM has a more favorable histological response than other treatments used before delayed replantation of avulsed teeth. This review followed the PRISMA checklist and was registered in PROSPERO. MEDLINE (PubMed), Embase, Scopus and Web of Science were searched from their inception to July 14, 2022. Data were independently extracted by two reviewers. Data were collected about species, number of animals, number and type of teeth, groups evaluated, extra-alveolar time, parameters for PBM and other study groups, presence and characteristics of containment, observation time points, evaluation methods, characteristics evaluated, and significant results. The ARRIVE and SYRCLE tools were used to assess the methodological quality and risk of bias (RoB) of the studies. After screening, six studies were included in the review synthesis. Three of the four studies that evaluated root resorption as an outcome found that PBM decreases its occurrence after delayed tooth replantation. A meta-analysis was not conducted because some data were missing in the included studies. Half of the studies evaluating ankylosis found an increase in its occurrence after PBM. Two studies evaluated inflammatory responses and found a reduction of inflammation after PBM. In general, studies had high methodological heterogeneity, intermediate reporting quality and high RoB. Despite the methodological quality and RoB limitations of the studies, the histological responses after delayed tooth replantation were more favourable in the PBM groups. Preclinical studies supported by guidelines should define laser parameters for future clinical studies.

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.

Prevalence and predictive parameters of external root resorption caused by retained wisdom teeth.

OBJECTIVES: The aim of this study was to estimate the prevalence and severity of external root resorption (RR) caused by retained third molars (M3), to compare the sensitivity of panoramic radiography (PAN) and cone beam computed tomography (CBCT) and to determine predictive factors for root resorption. MATERIALS AND METHODS: In a retrospective cross-sectional analysis, we included patients (N = 367) who underwent PAN and CBCT imaging between December 2017 and July 2019. Previous orthodontic treatment, age, gender, superimposition of second molars (M2) and M3 on PAN, retention depth, inclination angle and vertical level of contact with the M2 were used as predictor variables. The outcome variable was RR of the M2, graded according to Ericson et al. [1]. Subgroup analyses compared patients with and without suspected resorption in the PAN. RESULTS: While less than 5% of PANs suggested RR associated with M3, CBCT showed RR in 20% of all M2 with adjacent retained M3. The angle of inclination of M3, patient age and vertical level of molar contact emerged as predictive parameters, with mesial inclination, older age and deeper retention associated with increased severity of M2. CONCLUSION: Within the limitations of our study, these data confirm the poor performance of PAN in the diagnosis of RR. CBCT may be helpful in detecting RR in mesioangulated and deeply retained M3 in elderly patients, even when PAN did not suggest pathology. CLINICAL RELEVANCE: Our study may help to decide whether CBCT should be considered prior to M3 surgery.

Is there a relationship between the presence of external root resorption in second molars adjacent to impacted mandibular third molars with awake bruxism and masticatory muscle activity?

OBJECTIVES: This study aimed to assess whether awake bruxism and masticatory muscle activity could be related to external root resorption (ERR) in second molars adjacent to impacted mandibular third molars. MATERIALS AND METHODS: Sixty patients, with requests for a cone-beam, computed tomography, were divided into two groups: ERR (patients with ERR in the second molar, n = 30), and control group (n = 30). Awake bruxism was assessed through the Oral Behaviors Checklist (OBC) and an ecological momentary assessment (EMA). Surface electromyography (EMG) was used to assess the masseter and anterior temporal muscle function. Normality and homogeneity of variances were demonstrated. Descriptive analysis was performed, using the T-test and Chi-square test to compare the characteristics of the groups. A multiple regression model was performed. RESULTS: The ERR group presented more non-functional oral activities related to awake bruxism than the control group, according to OBC (p = 0.027) and EMA (p = 0.035). In addition, the ERR group had higher EMG activity than the control group in rest and isotonic protocols (p < 0.05). CONCLUSIONS: Awake bruxism and greater masticatory muscle activity seem to be related to the presence of ERR in second molars adjacent to impacted mandibular third molars. CLINICAL RELEVANCE: The results of the present study can reinforce the theory that triggering ERR in the second molars adjacent to impacted mandibular third molars may be related to mechanical forces coming from the masticatory function.

Evaluation of different irrigation activation techniques for the removal of various medicaments from a simulated internal resorption cavity: an in vitro study.

OBJECTIVES: This study aimed to assess the efficacy of different activation techniques in removing calcium hydroxide (Ultracal XS), Ledermix, and Bio-C Temp from simulated internal root resorption (IRR) cavities. MATERIALS AND METHODS: 108 single-rooted maxillary incisors were prepared using Reciproc R50 files. Simulated IRR cavities, 2 mm in diameter and located 8 mm from the apex, were created. Ultracal XS, Ledermix, and Bio-C Temp were applied to the samples, grouped by irrigation activation techniques: Standard Needle Irrigation (SNI), EDDY, Passive Ultrasonic Irrigation (PUI), and XP-endo Finisher (XPF). Medicament removal efficacy was evaluated using a standardized scoring system. Statistical analysis was performed using the Kruskal-Wallis test. RESULTS: XPF and PUI were more effective than SNI in medicament removal across the groups, with no significant difference. EDDY showed no significant difference than other groups. Ledermix was more effectively removed in all activation groups compared to Bio-C Temp. The XPF was superior in removing Ultracal XS compared to Bio-C Temp. However, none of the groups achieved complete medicament removal. CONCLUSIONS: XPF and PUI techniques enhance medicament removal efficacy. Bio-C Temp was more difficult to remove from the IRR cavities than other medicaments. CLINICAL RELEVANCE: Bio-C Temp could be removed from the canals less effectively compared to calcium hydroxide and Ledermix. Among the tested irrigation activation methods, XPF and PUI were found to be more effective at removing the tested medicaments.

Effect of ELVAX polymer subgingival implants with echistatin on extracted and reimplanted rats' teeth.

To investigate the effect of ELVAX polymer subgingival implants incorporated with echistatin peptide on incisor reimplanted tooth in rats. Forty-two male Wistars rats were divided into two groups: echistatin-treated rats (E) and control rats (C). The animals had their right maxillary incisors extracted and treated according to the International Association of Dental Traumatology replantation protocol. The extra-alveolar dry period was 30 and 60 min, and the post-surgical experimental periods were 15, 60, and 90 days. The samples were stained with H&E and analyzed for the presence of an inflammatory response, incidence of resorptions, and dental ankylosis. Results were statistically analyzed (p < 0.05). The presence of inflammatory resorption was significantly higher in group C at 30 and 60 min extra-alveolar time, in the 15-day postoperative period as compared with the E group (p < 0.05). Dental ankylosis was significantly more prevalent in group E in 30 min extra-alveolar time and 15 days postoperative period (p < 0.05). However, in 60 min extra-alveolar time and 60 days postoperative period, dental ankylosis was more prevalent in C group (p < 0.05). The use of ELVAX subgingival implants with echistatin demonstrated therapeutic potential in preventing the experimental resorption process after replantation of maxillary incisors in rats.

The consequences of orthodontic extrusion on previously intruded permanent incisors-A retrospective study.

AIM: The aim of this study is to compare the adverse effects that occur after orthodontic extrusion of teeth that have been traumatically intruded with those of similar teeth that have not experienced any trauma. BACKGROUND: The outcome of incisors intrusion can be affected by the patient's age, extent of injury, root development, and malocclusion. Orthodontic extrusion is a potential solution, but it may also cause complications. MATERIALS AND METHODS: A retrospective study of the effects of extrusion of traumatically intruded teeth was carried out. The study group included 21 teeth in 14 patients. The control group included 32 teeth in 10 patients that underwent orthodontic extrusion with no history of trauma. Patients' age, gender, and stage of root development were recorded. The severity of the intrusion was classified as mild (<3 mm), moderate (3-6 mm), and severe (≥7 mm). A comparison of signs of pulp necrosis and root resorptions between the groups was made. RESULTS: The central incisor is the tooth that is most injured in 80.9% of cases. A majority of these incidents involve severe intrusion, which was found in 42.9% of cases. 90% of the traumatized teeth had already lost their vitality prior to orthodontic treatment. Various forms of root resorption were observed in the study group. In the control group, 31.2% of teeth showed signs of external root resorption, but no endodontic intervention was carried out during the follow-up period, as these teeth remained vital. CONCLUSIONS: Following intrusion, there is a high risk for root resorption and pulp necrosis. Orthodontic repositioning should be carried out with caution and mild force to prevent complications. Long-term follow-ups are required to ensure the best possible outcome.

Reliability of information in YouTube™ videos on types of root resorption and related stimulating factors.

BACKGROUND/AIM: Root resorption occurs for various reasons and can also be seen as a treatment complication in orthodontics. This study aimed to assess the reliability and quality of YouTube™ videos on root resorption and to assess whether the videos referred to orthodontic treatment and other stimulation factors. MATERIALS AND METHODS: YouTube was searched using the keyword 'root resorption', which is the most searched term on Google Trends. The first 200 videos identified using the default filter 'sort by relevance' were used. Information such as the source, type, duration, and number of likes were recorded. Videos were analyzed using a 23-point content scale related to root resorption and divided into groups (poor, moderate, and excellent) based on the Global Quality Score. RESULTS: A total of 95 videos were included in the study. Most were uploaded by dentists or dental clinics (n = 64, 67.4%). The mean number of days since upload was 1536 ± 1254, and the mean duration was 5 ± 4 min. The videos had a mean of 80 ± 515 likes and 7043 ± 35,382 views, and a mean viewing rate of 1131.71 ± 8736.83. The most discussed topic was radiographic signs of root resorption. While the highest content score for the videos was 21, the average score was only 4. The mean GQS was 2 ± 1. Grouping videos by GQS showed that 55 (57.9%) were poor, 38 (40%) were moderate, and 2 (2.1%) were excellent. There was a significant relationship between videos that mentioned orthodontics (n = 62; 65.3%) and higher GQS (p = .036), and a significant difference was between GQS groups for total content levels (p < .001). CONCLUSIONS: YouTube videos related to root resorption lack sufficient information and clarity, and their quality needs to be improved. Oral health professionals should strive to produce higher-quality videos.

Risk of ankylosis of avulsed teeth immediately replanted or stored under favorable storage conditions before replantation: A long-term clinical study.

BACKGROUND/AIM: There are few long-term clinical follow-up studies on human teeth replanted immediately or after storage in a suitable storage medium prior to replantation. This study aimed to assess the risk of ankylosis in avulsed human teeth replanted immediately or after storage in physiological media for a short time. MATERIAL: Data from 116 patients with 145 replanted avulsed permanent teeth were selected from a comprehensive dental trauma database in Copenhagen University Hospital. The following teeth were selected: Group 1 comprised 36 teeth replanted immediately (dry time <6 min; wet time <6 min). Group 2 comprised 61 teeth replanted after physiologic storage media (saliva and saline) (dry time <6 min; wet time >5 min; wet time ranged from 7 to 170 min, and mean wet time was 59 min). Group 3 (control) included 48 teeth replanted after dry storage (dry time > 60 min). METHOD: Clinical and radiographic registrations were carried out according to a standardized protocol; follow-up ranged from 7 months to 23 years. Ankylosis was diagnosed by percussion test and radiographs and related to the conditions prior to replantation and stage of root development. RESULTS: The overall risk of ankylosis was 17.2% [95% CI: 4.61; 29.79] for immediately replanted teeth, 55.3% [95% CI: 42.54; 68.00] for teeth stored in physiologic media before replantation, and 85.7% [95% CI: 75.70; 95.73] for teeth stored dry more than 1 h. Mature teeth showed a significantly higher risk of ankylosis than immature teeth. CONCLUSION: This clinical long-term study has verified earlier experimental studies showing that immediate reimplantation has the lowest risk of ankylosis. Physiologic storage media are good alternatives that also reduce the risk of ankylosis compared to dry storage, where ankylosis is more likely although not always seen. Mature teeth are significantly more likely to develop ankylosis.