OBJECTIVES: To summarize the open-eruption technique of impacted anterior maxillary teeth, this study reports a technically improved operation on surgical exposure based on dental follicles and evaluates post-treatment periodontal health considering the effect of dental follicles. METHODS: Patients who underwent open-eruption technique with unilateral labially impacted maxillary central incisors were selected. The impacted teeth were assigned to the experimental group, and the contralateral unimpacted maxillary central incisors were assigned to the control group. In the surgical exposure, the new technique makes use of dental follicles to manage the soft tissue, so as to preserve soft tissue for better aesthetic results and healthier periodontal tissue. Tooth length, root length, alveolar bone loss, and alveolar bone thickness were recorded after the therapy. RESULTS: A total of 17 patients with unilateral maxillary central incisor impaction were successfully treated. The tooth length and root length of the two groups showed a statistically significant difference between the impacted and homonym teeth, with a shorter length in the impacted tooth (P<0.05). More labial alveolar bone loss was found in the experimental group compared with that in the control group (P<0.05). The outcomes of the cementoenamel junction width, pa- latal alveolar bone loss, and alveolar bone thickness did not indicate statistical significance between the experimental and control groups (P>0.05). CONCLUSIONS In the surgical exposure, the new technique uses dental follicles to manage the soft tissue and preserve it for better aesthetic results and healthier periodontal tissues.
Humans ; Tooth, Impacted/surgery* ; Incisor ; Alveolar Bone Loss/diagnostic imaging* ; Tooth Root ; Dental Sac ; Maxilla/surgery* ; Esthetics, Dental

OBJECTIVES: This study aimed to establish a new treatment of the mandibular second molars with external root resorption caused by impacted teeth to preserve the affected teeth and their vital pulps. METHODS: For mandibular second molars clinically diagnosed as external root resorption caused by impacted teeth, debridement and removal of the root at the resorption site via micro-apical surgery and direct capping of the pulp with bioactive material on the surface of the root amputation via vital pulp therapy were performed immediately after the impacted teeth were extracted. RESULTS: The external root resorption of the affected tooth was ceased. It was asymptomatic with intact crown, normal pulp, periapical alveolar bone reconstruction, normal periodontal ligament, continuous bone sclerosis, and no periapical translucency in radiographic examination at the 1-year postoperative follow-up, thus showing good prognosis. CONCLUSIONS Simultaneous combination of micro-apical surgery and vital pulp therapy after extraction of impacted teeth could successfully preserve mandibular second molars with ERR caused by impacted teeth and their vital pulps.
Humans ; Tooth, Impacted/surgery* ; Molar ; Mandible ; Dental Pulp ; Root Canal Therapy ; Root Resorption/etiology* ; Tooth Extraction

Post-and-core crown is one of the most common forms of restoration of tooth after root canal therapy (RCT). Infection control is the core objective of RCT, which is usually well realized by endodontists. However, many prosthodontists often neglect the infection control of the tooth and the maintenance of the curative effect of RCT during the process of post-and-core crown, which may lead to the failure of the final restoration. The concept of integrated crown-root treatment advocated recently requires clinicians to consider the RCT and final restoration as a whole, rather than simply divided into two parts-endodontic treatment and restorative treatment. As the core content of integrated crown-root treatment, infection control should be taken seriously by clinicians and implemented throughout the whole treatment process, especially in the restorative treatment that is easily overlooked after RCT. Therefore, this article describes the infection control of post-and-core crown restoration, classifies the tooth requiring post-and-core crown restoration, and puts forward the measures of infection control before and during post-and-core crown restoration, in order to provide reference and guidance for clinical practice.
Humans ; Crowns ; Tooth Crown ; Post and Core Technique ; Root Canal Therapy ; Infection Control ; Tooth Fractures

In dentistry, orthodontic root resorption is a long-lasting issue with no effective treatment strategy, and its mechanisms, especially those related to senescent cells, remain largely unknown. Here, we used an orthodontic intrusion tooth movement model with an L-loop in rats to demonstrate that mechanical stress-induced senescent cells aggravate apical root resorption, which was prevented by administering senolytics (a dasatinib and quercetin cocktail). Our results indicated that cementoblasts and periodontal ligament cells underwent cellular senescence (p21⁺ or p16⁺) and strongly expressed receptor activator of nuclear factor-kappa B (RANKL) from day three, subsequently inducing tartrate-resistant acid phosphatase (TRAP)-positive odontoclasts and provoking apical root resorption. More p21⁺ senescent cells expressed RANKL than p16⁺ senescent cells. We observed only minor changes in the number of RANKL⁺ non-senescent cells, whereas RANKL⁺ senescent cells markedly increased from day seven. Intriguingly, we also found cathepsin K⁺p21⁺p16⁺ cells in the root resorption fossa, suggesting senescent odontoclasts. Oral administration of dasatinib and quercetin markedly reduced these senescent cells and TRAP⁺ cells, eventually alleviating root resorption. Altogether, these results unveil those aberrant stimuli in orthodontic intrusive tooth movement induced RANKL⁺ early senescent cells, which have a pivotal role in odontoclastogenesis and subsequent root resorption. These findings offer a new therapeutic target to prevent root resorption during orthodontic tooth movement.
Rats ; Animals ; Root Resorption/prevention & control* ; Senotherapeutics ; Stress, Mechanical ; Dasatinib/pharmacology* ; Quercetin/pharmacology* ; Osteoclasts ; Tooth Movement Techniques ; Periodontal Ligament ; RANK Ligand

OBJECTIVE: To study the effect of various intracanal materials on the accuracy of oral maxillofacial cone-beam computed tomography (CBCT) for the diagnosis of vertical root fracture (VRF). METHODS: A total of twenty-four structurally intact single root canal dried and isolated teeth extracted for orthodontic treatment or periodontal disease were collected. The teeth were decrowned along the cemento-enamel junction (CEJ) and then used as samples for the study after conventional root canal preparation and post preparation. The 24 samples were divided into two groups with 12 samples in each group. Group A was the control group (no VRF group). According to intracanal materials, they were divided into five subgroups: blank group, fiber post group, gutta-percha point group, titanium post group and gold-palladium post group. Group B was the experimental group (VRF group), and subgroups were grouped as above. The VRF model was prepared by a unified method in the VRF group: the root was completely fractured in the buccolingual direction with a custom root canal nail and then cemented and reset. The control group was not subjected to the simulation of VRF. Titanium post and gold-palladium post were made according to the individuality of the root canal preparation, and the tightness of the post to the root canal wall was confirmed by X-ray radiograph. Then all the samples were scanned by CBCT in the isolate swine mandibular alveolar sockets. The diagnostic accuracy was statistically analyzed via blind interpretation by experienced endodontic specialists and oral and maxillofacial medical imaging specialists. RESULTS: The accuracy of the diagnosis of VRF in the blank group, fiber post group, gutta-percha point group, titanium post group, and gold-palladium post group in CBCT was 95.83%, 91.67%, 87.50%, 79.17%, and 45.83%, respectively. Compared with the blank group, the differences were not statistically significant in the fiber post group (P>0.999), the gutta-percha point group (P=0.500) and the titanium post group (P=0.125). The lowest diagnostic accuracy of VRF was found in the gold-palladium post group, and the difference was statistically significant compared with all other groups (P < 0.001). CONCLUSION Various intracanal materials have different degrees of influence on the diagnostic accuracy of VRF diagnosis in CBCT. The influence of fiber post, gutta-percha point and titanium post was small, while the influence of gold-palladium post was significant.
Animals ; Cone-Beam Computed Tomography/methods* ; Gold ; Gutta-Percha ; Palladium ; Swine ; Titanium ; Tooth Fractures/diagnostic imaging* ; Tooth Root/injuries* ; Reproducibility of Results

It is a basic prerequisite for the successful completion of endodontic treatment to thoroughly understand the root canal space anatomy. With the development of dental devices in dentistry, the root canal morphology of the mandibular first premolars can be presented in more detail. Before conducting root canal therapy on the mandibular first premolar with complex root canal morphology, it should be necessary to evaluate the potential difficulties and risks for making an appropriate treatment plan. The present paper reviews the research progress on the diversities of root canal morphology in mandibular first premolars in recent years, and then makes technologic recommendations based on the morphology diversities.
Humans ; Dental Pulp Cavity/diagnostic imaging* ; Bicuspid/anatomy & histology* ; Mandible ; Tooth Root/anatomy & histology* ; Root Canal Therapy

Objective: To measure and analyze the morphometric changes in the anterior alveolar bone during treatment and retention stage after retraction in bimaxillary adults using cone-beam CT(CBCT). Methods: Fifteen adult patients, four males and 11 females, aged 19 to 28 years[(22.2±3.1) years], who have completed orthodontic treatment and extracted four first premolar teeth for retraction in the Department of Orthodontics, The Affiliated Stomatological Hospital of Nanchang University from January 2016 to December 2018 were selected. CBCT was taken to assess the labial and palatal vertical bone level, total bone thickness at crest area, middle root area and apical area in pre-treatment (T1), post-treatment (T2) and at follow-up (maintained for more than two years) (T3). The differences in alveolar bone morphology at different stages were compared by single factor repeated measure ANOVA, and Pearson correlation analysis was performed on the amount of alveolar bone change in treatment stage and retention stage. Results: There were statistically significant differences in the alveolar bone height of the palatal side of maxillary anterior teeth, the labial side of maxillary lateral incisors and canine among three time points (P<0.05). The height difference of palatal alveolar bone of anterior teeth in T1-T2 stage was statistically significant (P<0.05). Palatal alveolar bone of upper and lower central incisors decreased by (1.52±0.32) and (4.96±0.46) mm, respectively. The height difference of anterior palatal alveolar bone was statistically significant in T2-T3 stage(P<0.05), the palatal alveolar bone height of central incisors increased by (1.20±0.27) and (3.14±0.35) mm respectively. The height difference of palatal alveolar bone in the anterior teeth of T1-T3 stage was statistically significant (P<0.05), and the height of palatal alveolar bone of central incisors was decreased (0.33±0.11) and (1.82±0.39) mm, respectively. There were statistically significant differences in the thickness of the cervical and middle root alveolar bone of anterior teeth among three time points (P<0.05). The difference of alveolar bone thickness of the cervical and middle root of anterior teeth at T1-T2 was statistically significant (P<0.05). decreased by (0.63±0.10) and (0.67±0.09) mm in lateral incisors, respectively. In the T2-T3 stage, the alveolar bone thickness of the crest area of the lower anterior teeth was significantly different (P<0.05), the alveolar bone thickness of mandibular central incisor crest area increased (0.09±0.03) mm. There were statistically significant differences in alveolar bone thickness in crest area and middle root of the incisors during T1-T3 stage (P<0.05), among which the middle root decreased by (0.38±0.16) mm and (0.63±0.13) mm, respectively. There was no statistically significant difference in other areas (P>0.05). The change of alveolar bone height in palatal side of upper anterior teeth at T2-T3 was very strongly negatively correlated with the change in T1-T2. The change of alveolar bone height in labial side of upper anterior teeth and lingual side of lower anterior teeth and the thickness of incisor root and neck were moderately strongly negatively correlated (r≤-0.8, P<0.001), the change of alveolar bone height in labial side of upper anterior teeth and lingual side of lower anterior teeth and the thickness of incisor crest area were moderately strongly negatively correlated (-0.8<r≤-0.4, P<0.05). Conclusions: For adult patients after retraction, anterior alveolar bone decreased significantly. In the retention stage, the same degree of bone apposition will occur, but still have alveolar bone loss compared with pre-treatment. The amount of alveolar bone change in the retention stage correlated with the amount of alveolar bone change in the treatment stage.
Male ; Female ; Humans ; Maxilla/diagnostic imaging* ; Cone-Beam Computed Tomography ; Tooth Root ; Malocclusion ; Palate

OBJECTIVE: To investigate the clinical application of cone-beam computed tomography (CBCT) among endodontic practitioners, and to analyze the indications and reasonability of CBCT in the diagnosis and treatment of pulpal and periapical diseases. METHODS: The clinical data were collected from patients who visited the Department of Cariology and Endodontology, Peking University School and Hospital of Stomatology and underwent CBCT examination from January to December, 2021. The data with their complete clinical information (including clinical records, radiology request forms/reports, two-dimensional and three-dimensional imaging data) were included. Those who underwent CBCT examination for orthodontic or prosthodontics were excluded. The experience and training background of the endodontic specialists, the number of patients treated in the whole year, the objective and region of interest (ROI) of CBCT examination, technical parameters, such as machine type, field of view (FoV) and radiographic reports were collected and analyzed to evaluate the impact on diagnosis. Wilcoxon and Mann-Whitney tests were used to compare the distribution of CBCT ROI. Chi-squared test and pairwise comparison were used to compare the application of CBCT by endodontic specialists with different clinical experience (senior, middle and junior). RESULTS: In 2021, a total of 3 308 CBCT scans were prescribed by 61 endodontic specialists who treated 34 952 patients throughout the year. 3 218 patients (male ∶female about 1 ∶2) amounting for 10% of the patients treated in the whole year who received CBCT scans with an median age of 35 years (28, 49). Around 98% CBCT examinations were performed after clinical examination and two-dimensional periapical radiographs were taken. The FoV of CBCT scanning less than 10 cm×10 cm accounted for 96% of the total number of the images. Among the 3 308 CBCT scans, 83% of the ROI were in posterior teeth, with a higher number of anterior teeth (Z=-2.278, P < 0.05). Maxillary and mandibular first molars accounted for 35% of the examined teeth. The objectives of CBCT scanning included three aspects: clarifying clinical diagnosis, guiding surgical and non-surgical endodontic treatment (including management of endodontic complications), and outcome assessment, accounting for 1 111 (34%), 1 745 (54%), 311 (10%), respectively. and the others 2%. In the diagnosis process, CBCT was mainly used for the diagnosis of chronic periapical periodontitis, root fracture, root resorption and dental trauma. In the study, 353 CBCT were used in the diagnosis of root fracture, with a positive diagnosis rate of 35% (125/353). 846 CBCT used to reveal the anatomy of the root canal system, of which 297 cases were used to find missed/extra canals after treatment failure, and 58% (171/297) were used to confirm the missed/extra canals. In the management of complications or errors, CBCT was mainly used to assist the diagnosis of perforation and to locate the separated instruments. In the study, 311 CBCT scans were used for outcome assessment, including 240 cases related to non-surgical treatment and 71 cases related to surgical endodontic treatment for follow-up or presence of clinical symptoms, and persistent lesions on 2D films. Among the 61 endodontic specialists who used CBCT, 23 (45%) were with senior experience, 15 (30%) with middle experience, and 23 (25%) with junior experience. The proportion of senior or junior experience prescribing CBCT examination was 10%, higher than that of middle experience (8%, χ₁²=39.4, χ₂²=29.1, P < 0.001). The application rate of chief endodontists was 18%, which was higher than that of associate chief endodontists (9%, χ₁²=139.4, P < 0.001). 31% (1 109/3 308) cases of diagnosis or treatment plans were changed after CBCT was taken. CONCLUSION Use of CBCT in endodontic practice could provide more clinical information, which is helpful for diagnosis, accurate treatment and prognosis evaluation.
Humans ; Male ; Adult ; Prevalence ; Root Canal Therapy/methods* ; Cone-Beam Computed Tomography/methods* ; Tooth ; Imaging, Three-Dimensional

OBJECTIVE: To investigate the effect of human subcutaneous adipose-derived stem cells (hADSCs) local transplantation on orthodontically induced root resorption (OIRR) and provide theoretical and experimental basis for the clinical application of hADSCs to inhibit OIRR. METHODS: Forty 8-week-old male Sprague Dawley rats were randomly divided into experimental group and control group, with 20 rats in each group, to establish the first molar mesial orthodontic tooth movement (OTM) model of rat right maxillary. The rats in the experimental group were injected with 25 μL of cell suspension containing 2.5×10 ⁵ hADSCs on the 1st, 4th, 8th, and 12th day of modeling, while the rats in the control group were injected with 25 μL of PBS. The rat maxillary models were obtained before and after 7 and 14 days of force application, and 10 rats in each group were killed and sampled after 7 and 14 days of force application. The OTM distance was measured by stereomicroscope, the root morphology of the pressure side was observed by scanning electron microscope and the root resorption area ratio was measured. The root resorption and periodontal tissue remodeling of the pressure side were observed by HE staining and the root resorption index was calculated. The number of cementoclast and osteoclast in the periodontal tissue on the pressure side was counted by tartrate resistant acid phosphatase staining. RESULTS: The TOM distance of both groups increased with the extension of the force application time, and there was no significant difference ( P<0.05). There was no significant difference in OTM distance between the experimental group and the control group after 7 and 14 days of force application ( P>0.05). Scanning electron microscope observation showed that small and shallow scattered resorption lacunae were observed on the root surface of the experimental group and the control group after 7 days of force application, and there was no significant difference in the root resorption area ratio between the two groups ( P>0.05); after 14 days of application, the root resorption lacunae deepened and became larger in both groups, and the root resorption area ratio in the experimental group was significantly lower than that in the control group ( P<0.05). The range and depth of root absorption in the experimental group were smaller and shallower than those in the control group, and the root absorption index in the experimental group was significantly lower than that in the control group after 14 days of force application ( P<0.05). The number of cementoclast in the experimental group was significantly lower than that in the control group after 7 and 14 days of force application ( P<0.05); the number of osteoclasts in the experimental group was significantly lower than that in the control group after 14 days of force application ( P<0.05). CONCLUSION Local transplantation of hADSCs may reduce the area and depth of root resorption by reducing the number of cementoclasts and osteoclasts during OTM in rats, thereby inhibiting orthodontic-derived root resorption.
Rats ; Male ; Humans ; Animals ; Root Resorption/therapy* ; Rats, Sprague-Dawley ; Osteoclasts ; Tooth Movement Techniques ; Stem Cells

Over the past decade, dramatic progress has been made in dental research areas involving laser therapy. The photobiomodulatory effect of laser light regulates the behavior of periodontal tissues and promotes damaged tissues to heal faster. Additionally, photobiomodulation therapy (PBMT), a non-invasive treatment, when applied in orthodontics, contributes to alleviating pain and reducing inflammation induced by orthodontic forces, along with improving tissue healing processes. Moreover, PBMT is attracting more attention as a possible approach to prevent the incidence of orthodontically induced inflammatory root resorption (OIIRR) during orthodontic treatment (OT) due to its capacity to modulate inflammatory, apoptotic, and anti-antioxidant responses. However, a systematic review revealed that PBMT has only a moderate grade of evidence-based effectiveness during orthodontic tooth movement (OTM) in relation to OIIRR, casting doubt on its beneficial effects. In PBMT-assisted orthodontics, delivering sufficient energy to the tooth root to achieve optimal stimulation is challenging due to the exponential attenuation of light penetration in periodontal tissues. The penetration of light to the root surface is another crucial unknown factor. Both the penetration depth and distribution of light in periodontal tissues are unknown. Thus, advanced approaches specific to orthodontic application of PBMT need to be established to overcome these limitations. This review explores possibilities for improving the application and effectiveness of PBMT during OTM. The aim was to investigate the current evidence related to the underlying mechanisms of action of PBMT on various periodontal tissues and cells, with a special focus on immunomodulatory effects during OTM.
Humans ; Inflammation ; Low-Level Light Therapy/adverse effects* ; Orthodontics ; Root Resorption/therapy* ; Tooth Movement Techniques