Roots Of Molars Research Articles

Can herbal products be alternative root canal irrigation solutions in primary teeth? An in vitro study

To evaluate antimicrobial properties and smear layer removal efficiency of various plant extracts and apple cider vinegar (AV). A total of 112 primary molars roots were randomly divided into two groups (n = 56) for antimicrobial test and infected with E faecalis and Candida albicans then divided again into 7 groups (n = 8) as physiological saline (PS), NaOCI, white tea (WT), Helichrysum arenarium (HA), AV, Citrus lemon (CL), and Anzer thyme (AT). Disinfecting abilities were measured with ImageJ. In the smear layer removal efficiency test, prepared 70 roots were divided into 7 groups (n = 10) as in the antimicrobial test also 2 subgroups were designed as with or without EDTA usage (n = 5). All samples were examined under SEM. Open dentin tubule percentage was evaluated with ImageJ. HA and CL showed higher antibacterial activity against E. faecalis than PS (p = 0.038, p = 0.009) Antifungal activity of AV against C. albicans was higher than saline (p < 0.001). AV in the coronal third and CL in the middle third removed more smear layer than saline and NaOCI (p < 0.05). In the coronal region, HA and AV showed similar smear layer removal efficacy to NaOCl + EDTA (p > 0.05). CL, HA, and AV presented statistically similar results to NaOCl + EDTA in smear layer removal efficacy in the middle region (p > 0.05). CL and AV have antimicrobial efficacy against E. faecalis and C. albicans respectively and smear layer removal activity.

Dental niche cells directly contribute to tooth reconstitution and morphogenesis.

Mammalian teeth develop from the inductive epithelial-mesenchymal interaction, an important mechanism shared by many organs. The cellular basis for such interaction remains elusive. Here, we generate a dual-fluorescence model to track and analyze dental cells from embryonic to postnatal stages, in which Pitx2+ epithelium and Msx1+ mesenchyme are sufficient for tooth reconstitution. Single-cell RNA sequencing and spatial mapping further revealed critical cellular dynamics during molar development, where tooth germs are organized by Msx1+Sdc1+ dental papilla and surrounding dental niche. Surprisingly, niche cells are more efficient in tooth reconstitution and can directly regenerate papilla cells through interaction with dental epithelium. Finally, from the dental niche, we identify a group of previously unappreciated migratory Msx1+ Sox9+ cells as the potential cell origin for dental papilla. Our results indicate that the dental niche cells directly contribute to tooth organogenesis and provide critical insights into the essential cell composition for tooth engineering.

Root and canal morphology of maxillary second molars in a Black South African subpopulation using cone-beam computed tomography and two classifications.

This study investigated the root and canal morphology of maxillary second molars in a Black South African population using high-resolution cone-beam computed tomography. In total, 386 maxillary second molar teeth were evaluated and described according to the classifications of Vertucci (with the additions of Sert and Bayirli), as well as Ahmed et al. Root number, fusions and canal morphology were recorded. Relationships between morphology, sex and age were assessed using Fisher's exact test (p < 0.05). Maxillary second molars were predominantly three-rooted (96.1%), with root fusion observed in 14%. No relationships between sex, age and canal morphology were found. Additional canals were observed in 67.4% of mesiobuccal roots. The Ahmed et al. classification provided a better overall description of the morphology. In this population, maxillary second molar teeth exhibited a diversity of root and canal morphology. Complex variations may render endodontic management more difficult and increase the possibility of missed anatomy.

Cone-beam computed tomography study of the incidence and characteristics of the second mesiobuccal canal in maxillary permanent molars.

Objective: This study aimed to review the characteristics of the second mesiobuccal canal (MB2) in the maxillary first and second permanent molars of 500 patients to analyze the incidence of MB2 and its connection with gender, age, tooth position, and mesiobuccal (MB) root length. The study also aimed to investigate the distribution of the root canal orifice on the pulp chamber floor to obtain an imaging reference for clinical practices related to maxillary molars in Fujian, China. Methods: In accordance with the enrollment criteria, cone-beam computed tomography images of the maxillofacial area were collected from 500 patients, including 1,000 maxillary first molars and 1,000 maxillary secondmolars. The patients were grouped according to gender and tooth position. The incidence of MB2 was observed, and the MB root length and distribution angle of the mesiobuccal-palatal-distobuccal root canal orifices were measured for statistical analysis. Results: The overall incidence of MB2 in maxillary first and secondmolars was 51.1% and 32.9%, respectively. The incidence of MB2 in maxillary molars was 50% in male patients and 35.45% in female patients, with a significant difference (p < 0.05). The incidence of MB2 in maxillary molars was significantly higher in subjects aged below 50 (especially in male patients) than those aged 50 and above. The MB root length of maxillary first and secondmolars with MB2 was longer than that without MB2, and the difference was statistically significant. An association was identified between the incidences of MB2 in contralateral molars of the same type and in ipsilateral adjacent molars. When MB2 occurred in the MB root of maxillary molars, the root canals were mostly classified as type IV, followed by type II. The angle formed by the MB-P-DB orifices on the pulp chamber floor in the maxillary first and secondmolars was (25.23 ± 5.20) and (20.17 ± 10.88)°respectively. Conclusion: The incidence of MB2 in maxillary molars is high in Fujian, China. The occurrence of MB2 is affected by gender, age, and length of MB root, and it occurs symmetrically in adjacent molars and in contralateral molars of the same type. In addition, the distribution law of the main root canal orifice at the pulp chamber floor is conducive to locating MB2, thereby guiding clinical operations.

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

The aim of this study was to compare the difference in length and width of the mandibular retromolar space (RMS) stratified by the different eruption and impaction statuses of the third molars in patients with skeletal Class I malocclusion. The right mandibular RMS in 186 adult patients categorized according to the different statuses of the third molar was analyzed by using cone-beam computed tomography (CBCT). The shortest distances between the inner lingual cortex of the mandibular body and second molar root were measured parallel to the posterior occlusal line (POL) at depths of 2, 4, 6, 8, and 10mm (mandibular retromolar space length in root level, RLin2,4,6,8,10) on the axial slices with the cementoenamel junction (CEJ) as the reference level. The width of the RMS and second molar root was measured vertical to the POL at the terminal point of the molar distalization at depths of 2, 4, 6, 8, and 10mm (width of the mandibular retromolar space, BW2,4,6,8,10/ width of the second molar distal root, TW2,4,6,8,10) from the CEJ. RL in different measurement planes was 2.72 ± 2.22 ~ 3.74 ± 2.26 for Group A, 5.27 ± 1.68 ~ 9.10 ± 2.04 for Group B, 1.94 ± 2.34 ~ 5.71 ± 4.37 for Group C, 1.83 ± 2.95 ~ 5.05 ± 4.24 for Group D, and 5.93 ± 3.97 ~ 10.52 ± 2.16 for Group E. The BW measurement results for A ~ E group were 9.71 ± 1.41 ~ 10.51 ± 1.81, 9.83 ± 1.39 ~ 12.55 ± 2.11, 9.96 ± 1.21 ~ 12.17 ± 1.62, 9.82 ± 1.47 ~ 12.28 ± 2.77, and 10.02 ± 1.20 ~ 12.75 ± 0.82, respectively. There was no significant difference between men and women in any measurements (P > 0.05). Patients with normal third molars erupted and those vertically impacted possessed larger RMS lengths than those in which the third molars were missing, horizontally impacted or mesially impacted (P < 0.05). In each measurement plane, TW was significantly smaller than BW (P < 0.05). Sex had no effect on the length or width of the mandibular RMS. Different statuses of third molars can also differentially affect the mandibular RMS. The mandibular RMS width is not a limit for mandibular molar distalization. When considering the distalization of mandibular molars, more attention should be directed to the lingual cortex of the mandible, and CBCT scans are recommended for patients who require significant mandibular molar distalization. The mandible buccal shelf and retromolar area maybe a safe zone to insert the miniscrew for molar distalization.

A quantitative analysis of macrophage-colony-stimulating factor in peri-miniscrew implant crevicular fluid before and after orthodontic loading.

To analyze macrophage-colony-stimulating factor (M-CSF), a bone remodeling biomarker in the peri-miniscrew implant crevicular fluid (PMICF) after insertion and orthodontic loading. This prospective study included 40 miniscrew implant (MSI) sites in 10 subjects undergoing fixed orthodontic mechanotherapy utilizing miniscrew anchorage. After dental alignment, miniscrews were inserted between the second premolar and first molar roots. After 21 days of insertion, MSIs were direct loaded with closed-coil springs (200 g force) for en masse retraction of anterior teeth. PMICF was collected with Periopaper™ strips from the gingival crevice around MSIs at six time points (T1-T6: 1 hour, 1 day, 21 days postinsertion, and 7, 21, and 42 days postloading). PMICF was quantified for M-CSF by enzyme-linked immunosorbent assay. Paired comparison of mean M-CSF concentrations before and after loading stages (T1-T6) was made using the Wilcoxon signed-rank test. The mean M-CSF concentration showed a significant peak at T3 (21 days postinsertion; 12.646 pg/mL; T1 vs T3: P < .0001). After orthodontic loading of miniscrews, M-CSF levels increased to 13.570 pg/mL at T4 (7 days after loading; T1 vs T4: P < .001) and maintained at a plateau to T5 (21 days postloading; 11.994 pg/mL). However, the difference between preloading and postloading was not statistically significant (T3 vs T4). The maximum M-CSF activity around MSIs was observed at around 3 weeks of miniscrew insertion, suggesting underlying bone remodeling after surgical injury. However, orthodontic force on MSIs did not cause any significant surge in M-CSF levels postloading.

Assessment of the Proximity of the Inferior Alveolar Canal with the Mandibular Root Apices and Cortical Plates-A Retrospective Cone Beam Computed Tomographic Analysis.

116 cone beam computed tomography (CBCT) scans were examined and the shortest distance of IAC with the root apices of mandibular canines, premolars and molars, and with cortical plates was analyzed. The data were statistically analyzed using SPSS. The shortest mean distance between IAC and lingual cortical plate (LCP) was found in the third molar area, and between IAC and buccal cortical plate (BCP) in the second premolar area. A high incidence of 60% direct communication (DC) was present in mandibular second molars; 38% in mandibular third molars; 13% in mandibular second premolars; 12% in mandibular first molars; and 1% in mandibular first premolars. Anteriorly, IAC was found to be significantly present in close approximation to the roots of mandibular canines. Posteriorly, IAC was found to be in significant proximity to the distal roots of mandibular second molars.

Clinical effectiveness of buccally and palatally anchored maxillary molar distalization: The miniscrew-supported 3-dimensional maxillary bimetric distalizing arch vs the Beneslider

This study aimed to investigate the dentoalveolar and skeletal changes achieved with a novel miniscrew-supported 3-dimensional maxillary bimetric distalizing arch (3D-MBDA) and the Beneslider. In addition, the study aimed to compare these changes between each other and with an untreated control group. Sixty-five patients with bilateral Class II molar relationship and fully-erupted maxillary second molars were included in the study. Of these patients, 23 received the miniscrew-supported 3D-MBDA (group 1), 21 received the Beneslider (group 2), and 21 served as untreated control subjects (group 3). Lateral cephalometric films and dental casts, taken at the beginning and the end of maxillary molar distalization, were analyzed to study the differences between the groups. The crown distalization of the first molars was similar between the treatment groups (group 1, 3.1 mm; group 2, 3.3 mm); however, root distalization was significantly more in group 1 (5 mm) when compared with group 2 (1.7 mm). The first molars tipped 6.2° in the mesial direction in group 1 and 8.2° in the distal direction in group 2. The mesiobuccal cusp tip of the first molars extruded for 1.2 mm and increased vertical dimensions in group 2, whereas it intruded for 1.7 mm in group 1. Meanwhile, aforementioned parameters presented insignificant changes throughout the observation period in the control group. Inter-first molar width increased significantly in group 2 (2.7 mm). Distalization time was similar between the groups (group 1, 14 months; group 2, 15 months). The distalization rate was higher in group 2 (0.27 mm/mo) than in group 1 (0.23 mm/mo) measured from the crowns; however, it was similar between the groups (group 1, 0.25 mm/mo; group 2, 0.19 mm/mo) when measured from the trifurcation point. The miniscrew-supported 3D-MBDA was more effective in distalizing molar roots and maintaining vertical parameters and dental arch width while tipping the molars mesially. In contrast, the Beneslider distalized molar crowns faster, resulting in significant distal tipping.

Radicular dentinal microcracks during biomechanical root canal preparation using four minimally invasive endodontic files.

The aim of the study was to compare the dentinal microcrack formation on human mandibular molars using 4 different minimally invasive file systems at 3, 6 and 9 mm from apex using a stereomicroscope. 125 mesial roots of mandibular molars were randomly divided into 5 groups and instrumented (n=25). Group 1: Control Group (CG), Group 2: Self Adjusting File (SAF), Group 3: XP-Endoshaper (XP), Group 4: TRUShape (TS), Group 5: V Taper 2H (VT). After instrumentation was completed, the roots were sectioned at 3 mm, 6 mm, and 9 mm from apex using a slow-speed circular saw. Digital images were captured using a 24× stereomicroscope by using a digital camera. Two operators independently checked each specimen for the presence of dentinal defects. Statistical comparison between the file systems was done using Chi-square (p<0.05). There was no statistically significant difference in the frequency of microcracks between the groups of file systems (X2=4.509, p>0.05). VT file system exhibited higher microcracks (25%) but was not statistically significantly higher than XP (12%), TRUShape (12%), and SAF (4%) endodontic file systems. Within the limitations of this study, it can be concluded that all the file systems used in our research are minimally invasive files and produced few dentinal microcracks. VT files produced maximum while SAF produced the least number of micro-cracks.

3D biomechanical intrusion effects of infra zygomatic bone screws and temporary anchorage device on total maxillary dentition in treatment of vertical maxillary excess: A FEM study

Many studies have reported on the application and clinical efficiency of full arch maxillary dentition intrusion mechanics; however, studies about biomechanical effects such as stress, strain, and displacements on the teeth and the surrounding tissues are limited. The objectives of study was to evaluate and compare the stress distribution and displacement of total maxillary dentition under intrusion mechanics using a three-dimensional finite element analysisA three-dimensional finite element model was constructed based on computed tomography scan data, and it served basic model. The geometric model was converted to finite element model using Altair HyperMesh software. Model A with pre-adjusted edgewise appliance (PEA) setup and Model B with occlusal Splint setup was evaluated and compared for von mises stress distribution and displacement of total (full arch) maxillary dentition by using three dimensional finite element analysis; with force delivered from infrazygomatic screws and miniscrew. Force levels for Model A and Model B includes a total of 300grams of intrusive force (each side) on maxillary posterior segment from IZC bone screw and 100grams of intrusive force on anterior segment from miniscrew.In the model A; with PEA setup reinforced with two trans-palatal arches, highest von Mises stress of 0.970 Mpa was produced on second molar roots followed by molar roots and premolars and central and lateral incisors roots. In the Model A, maximum intrusive values was seen on crown tip of central and lateral incisors (8.671µm), and lowest displacement values on second molars (2.230µm). Similar pattern of von Mises stress distribution and displacement was observed in the Model B. Model A and Model B provided an effective en masse vertical control of the full arch maxillary dentition. Higher intrusion displacement values were seen in anterior segment than the posterior segments

Effects of aging on the evolution of Apical Periodontitis lesions in rats

This study aimed to evaluate the effects of aging on the evolution of Apical Periodontitis (AP) lesions in rats. Elderly males (study group, n = 12) and young males (control group, n = 12) Wistar rats were used. When the study group were 24 months old and the control group were 3 months old, AP lesions were induced by creating pulp exposure of the mandibular left first molars. After 21 and 40 days, the animals were euthanized and the mandibles were removed. The left hemi- mandibles were radiographed and the AP lesions of the mesial roots of the first molars were measured using ImageJ software (National Institute of Mental Health, Bethesda, USA). The AP lesions were significantly larger in the Elderly (E) group (p = 0.0006) compared to the Control (C) group (E 21: 218.8 ± 72.96, C 21: 94.77 ± 9.44, E 40: 237.8 ± 57.20, C 40: 85.23 ± 6.63). The lesions of the animals in the elderly groups were significantly larger than the lesions in the younger animals. These findings suggest that the bone and immunological changes caused by aging can influence the progression of AP lesions.

Microtomographic Assessment of the Shaping Ability of the Hyflex CM and XP-endo Shaper Systems in Curved Root Canals.

This study compared the shaping ability of the Hyflex CM and XP-endo Shaper rotary file systems in curved mesial canals of mandibular molars using micro-computed tomography. Seventeen mesial roots of extracted first mandibular molars with two independent mesial canals were scanned before and after root canal preparation with the tested rotatory file systems. Each mesial canal from the same specimen was prepared with one of the two systems. The parameters analyzed were canal centering (transportation) for the cervical, middle, and apical segments, as well as for the entire canal (0-10 mm from the apex); and canal volume increase, canal surface area increase, and unprepared canal walls for two segments, 0 to 4 mm and 0 to 10 mm from the apex. There was no significant difference between both systems regarding canal centering (transportation), volume increase, and unprepared canal walls for the 0 to 10 mm segment (p> 0.05); however, a significant difference was observed for the 0 to 4 mm segment (p <0.01), where the Hyflex CM left 28.46% of unprepared walls and XP-endo Shaper left 13.26%. The shaping ability of the two tested rotatory file systems in mesial roots of first mandibular molars was similar for all parameters in all the segments evaluated, except for the 0 to 4 mm segment, where XP-endo Shaper left a smaller area of unprepared canal walls than Hyflex CM.

Evidence of late root formation of molars in Anderson’s red-backed vole, Eothenomys andersoni (Thomas, 1905) (Cricetidae, Rodentia), and arguments for its generic allocation

We evaluated the molars in Anderson's red-backed vole (n = 114) from the Kii Peninsula of Honshu, Japan. Two of the specimens are considered extremely old aged based on their dimensions and on the loss of alveolar capsules of M2, and a third one is also old based on its strongly worn left M3 and M1. Of the former two individuals, one showed an incipient closure of re-entrant angles at its basal end, as estimated from the difference between the occlusal patterns of the occlusal and basal surfaces of the left M2. The latter individual also showed a complete closure of the basal end in the left M3. These patterns differ from incipient roots observed in other vole taxa but were similar to a previous example of incipient roots in Anderson's red-backed vole. Therefore, we suggest that molar roots in this species form at an extremely late age or by strong wear. Root formation in molars is considered an important diagnostic character, as Eothenomys molars lack roots, while Craseomys molars develop roots at a late age. However, this dental character may be particularly difficult to assess in voles under natural conditions. Considering previous phylogenetic findings based on molecular analyses, Craseomys is the most appropriate genus for Anderson's and other Asiatic red-backed voles.

A Case of Chronic Maxillary Sinusitis in a Late Neanderthal Population of the Altai Mountains

We describe a likely case of chronic maxillary sinusitis (CMS) in a Neanderthal skeletal sample from Chagyrskaya Cave, in the Altai Mountains. Signs of CMS were recorded in the Chagyrskaya 57 specimen, which is a fragment of a left maxilla. Alveoli of the upper fi rst molar are partially preserved, and so are the second and third upper molars, with adjacent parts of the walls, and the fl oor of the maxillary sinus. The fragment was found in layer 6b, dating to 53,100–51,100 BP. We analyze the factors that had caused the development of the disease, and assess its etiology. In the 3D-model, generated by computed microtomography, and in the original specimen, porotic changes were registered, situated at the fracture line of the alveoli of M1, lost post-mortem, and near the vestibular roots of both preserved molars. Also, there were isolated bone spicules, 1.0–2.6 mm in size. These signs indicate incipient CMS, evidently caused by chronic periodontal disease combined with a deep alveolar recess of the maxillary sinus. As the periodontal gap expanded, several small nutrient foramina, piercing the bottom of the sinus, merged. As a result, several oro-antral channels formed, whereupon the infection spread into the maxillary sinus. Since the deep alveolar recess is observed in the vast majority of Neanderthal crania with published images or reconstructed maxillary cavities, it can be assumed that Neanderthals were predisposed to odontogenic CMS.

Is it necessary to remove bone-impacted teeth? A retrospective study

BackgroundIn clinical practice, it is risky to extract bone-impacted teeth and they're prone to a variety of complications, such as pathological fracture, adjacent tooth fracture, maxillary sinus perforation, and so on, making it difficult for clinicians to decide whether to extract them. PurposeIn order to illustrate our opinions on the possibility of extracting full third molars (M3), 360 examples of complete third molars were analyzed in this study. Materials and methodWe investigated 2189 patients, and 261 of them provided CBCT images of 360 teeth. assessing the degree of second molar(M2) root absorption in connection to age, impacted relationship, contact part, calculating the odds ratio (OR) and 95% confidence interval using the Logistic regression analysis equation. ResultBone-impacted M3 occurred in 11.92% (261/2189) of patients with "impacted teeth" diagnoses. There was a significant difference between the occurrence of M2ERR and the contact parts (P value<0.001), and only the type of vertical impaction differed significantly from Level 3 (P < 0.05). Conclusions1) M3 should be removed if root resorption has not occurred in M2. 2) Root resorption is more likely to occur when M3 crown and M2 apical contact. 3) Enough experience, precise preoperative assessment can reduce the dangers to a minimum.

Complex root anatomy of upper molar with presence of three mesiobuccal canals

The mesiobuccal root of the upper molars usually presents anatomical complexities that limit the correct cleaning and shaping. This results in treatments with a high incidence of failure, which is why knowledge of the internal anatomy is essential. The presence of three main canals in the mesiobuccal root of maxillary molars is infrequent, which can make root canal treatment difficult. A clinical case of a maxillary left first molar with three mesiobuccal canals is presented here.

Analysis of the mandibular molars root canals morphology. Study by computed tomography.

This study aimed to analyze the root and root canal morphology of mandibular first and second molars using CBCT images. A total of 2,400 mandibular molars exams were selected from 600 patients aged between 18 and 75 years. The number of roots, number of root canals, and root canal configuration according to the Vertucci classification were verified. Overall, 94.92% of mandibular first molars and 90.17% of mandibular second molars had two separate roots. Among the biradicular molars, the first molars showed a greater incidence of type IV canals in the mesial root and type I in the distal root. In the second molars, the most common canal form was type IV in the mesial root and type I in the distal root. In the triradicular molars, the type IV and type I configurations were the most common in the mesial root of the first molar and second molar, respectively. In both triradicular molars, there was a prevalence of type I canal in the distal and DL roots. Statistical analysis was performed at a significance level of 0.05. The number of roots was correlated with gender (Spearman test), and the canal's configuration with gender and bilaterality (Wilcoxon test). The subpopulation studied has a high incidence of bilateral symmetry and mandibular molars with two roots with two distinct mesial canals and one distal canal. The bilateral configuration is possible to estimate the number of canals, especially in images that are difficult to visualize, such as atresic canals.

Evaluation of the Ability of Panoramic Radiography in the Determining the Morphology and Position of third Molar Roots

Introduction: Most third molars eventually need to be extracted, and this tooth has the most varied and unpredictable root position of all teeth. Therefore, considering the importance of accurate diagnosis of the roots of molar teeth before surgery to reduce its surgical complications, the aim of this study was to evaluate the ability of panoramic radiography to diagnose the situation of roots of third molars. the relationship of the roots to each other and the angle of the crown to the root in panoramic and clinical radiographs, respectively, using Romexis viewer and digimizer software were investigated.&#x0D; Methods: In this cross-sectional-analytical study, 104 third molars of 93 patients referred for wisdom tooth extraction were examined clinically for the number of roots, the relationship of roots to each other and the angle of the crown to the root in panoramic radiography using Romexis Viewer software and clinically after providing photograph and measuring the angle using digimizer software.&#x0D; Results: In evaluating the roots of third molars, the accuracy of panoramic radiographic interpretation regarding the number of roots was 63.27% and in the presence or absence of root, adhesion was 55.89%. In addition, Pearson correlation analysis showed that there was a significant relationship between the reported angle in radiographic interpretation and the actual angle (r = 0.318 and P value = 0.001).&#x0D; Conclusion: Therefore, panoramic radiography is a valuable guide for third molar surgery. It is only necessary to consider its high error rate in terms of morphological details such as the number of roots and their relationship to each other.

A Case Treated with Maxillary Molar Distalization through the Maxillary Sinus: Three-Dimensional Assessment with a Cone-Beam Computed Tomography Superimposition

In this report, we describe a successful orthodontic treatment through the maxillary sinus and show the utility of cone-beam computed tomography (CBCT) for this procedure. A 20-year-old man with Class I molar relationships and crowding of the maxillary and mandibular anterior teeth came to us to improve his malocclusion. Maxillary molar distalization was necessary to reduce the crowding of the teeth. This was achieved by the use of temporary anchorage devices (TADs) and the uprighting of the mandibular molars. However, several roots of the maxillary molars protruded into the maxillary sinus. The maxillary sinus is a known barrier to orthodontic tooth movement, leading to root resorption and/or tipping movement. We aimed to distalize the maxillary molars through the maxillary sinus by bodily movement. The findings were three-dimensionally confirmed by using the superimposition of CBCT obtained before and after the treatment.

Macrophages with Different Polarization Phenotypes Influence Cementoblast Mineralization through Exosomes.

Root resorption is a common dental challenge that can lead to tooth loosening or even tooth loss. Among the cells involved in root resorption, cementoblasts are responsible for laying down the cementum, while macrophages with different phenotypes have also been shown to have bidirectional effects on root resorption. However, the relationship between macrophages and cementoblasts remains largely unknown. In this study, we examined the effect of macrophages with different polarization phenotypes on the mineralization of cementoblasts. Using the transwell coculture system and a conditioned medium-based coculture system, we found that compared with M0 (unpolarized macrophages), M1-polarized macrophages attenuated cementoblast mineralization, while M2-polarized macrophages enhanced cementoblast mineralization. Furthermore, by extracting M0/M1/M2 macrophage exosomes and examining their effects on the mineralization of cementoblasts, we found that the effects of macrophages on cementoblast mineralization were, at least partially, exerted by exosomes. Moreover, in vivo studies also indicated that an increased M1/M2 ratio could suppress cementoblast mineralization and bring about root resorption. During mechanical force-induced orthodontic tooth movement (OTM), root resorption was evident on the compression side of periodontal tissue, and a higher M1/M2 ratio and weaker cementoblast mineralization were observed on the compression side than on the tension side. We also used localized lipopolysaccharide (LPS) injection to increase the M1/M2 ratio around the roots of maxillary molars, where root resorption and decreased cementoblast mineralization were also observed. Furthermore, when we injected the exosomes from M0 and M1- and M2-polarized macrophages into mice, it was observed that the cementoblast mineralization was attenuated in the group injected with M1-polarized macrophage exosomes, while it was augmented in the group injected with M2-polarized macrophage exosomes.