Complex crown-root fractures in the esthetic zone refer to a type of dental trauma occurring in the anterior region, characterized by concurrent fractures involving both the crown and the root, with associated pulp exposure and periodontal tissue injury. These injuries consistently exhibit critical anatomical features, including a fixed palatal fracture location below the alveolar crest, compromised residual tooth structure, and frequent encroachment of the biological width. To predict treatment outcomes, a risk assessment framework based on the restoration-tooth-periodontium interface was developed. Resistance risk was evaluated by assessing the type of residual dentin ferrule and the length of the root within the alveolar bone, while periodontal risk was assessed according to gingival phenotype and alveolar bone morphology. Based on these risk dimensions and the principles of aesthetics, stability, and minimally invasive treatment, a diagnostic classification system was established to categorize fractures into three types: favorable, intervention and high-risk. Type-specific management strategies were proposed: for favorable cases, crown lengthening combined with deep margin elevation to reduce periodontal risk is recommended; for intervention cases, orthodontic extrusion or surgical extrusion is applied to simultaneously address both ferrule deficiency and biological width violation; for high-risk cases, extraction followed by implant restoration is advised due to limited root preservation value. The presented classification enables clinicians to adopt a scientific and structured approach to treatment planning for these complex crown-root fractures in the aesthetic zone.
Humans ; Tooth Fractures/therapy* ; Tooth Root/injuries* ; Risk Assessment ; Tooth Crown/injuries* ; Periodontium ; Esthetics, Dental ; Dental Restoration, Permanent/methods*

OBJECTIVES: This study aimed to evaluate the clinical application value of in-situ crown reattachment technique combined with pulpotomy in the treatment of complicated crown-root fractures in young permanent anterior teeth. METHODS: A prospective study was conducted on 50 children with complicated crown-root fractures in young permanent anterior teeth, who were treated at the Pediatric Dentistry Department, Hospital of Stomatology, Xi'an Jiaotong University from June 2023 to June 2024. All patients underwent in-situ crown reattachment technique combined with pulpotomy. Clinical examinations, radiographic evaluations, and subjective satisfaction surveys (using a Likert scale of 1-10) were conducted at 1, 6, and 12 months postoperatively. Data were analyzed using SPSS 23.0. RESULTS: The loss-to-follow-up rate was 12% (6/50), with 44 cases completing the 12 months of evaluation. The clinical success rate was 93.18% (41/44), and the radiographic success rate was 97.73% (43/44). The subjective satisfaction scores showed a significant improvement in masticatory function from 7.03±0.52 at 1 month to 8.07±0.92 at 12 months postoperatively (P<0.05), whereas the scores for aesthetics, comfort, and quality-of-life impact showed no statistically significant differences (P>0.05). CONCLUSIONS In-situ crown reattachment technique combined with pulpotomy effectively treats complicated crown-root fractures in young permanent anterior teeth, demonstrating a high short-term clinical success rate, significantly improved masticatory function, and minimally invasive preservation of pulp vitality and root development potential. This technique provides an optimized treatment option for dental trauma in children, although its long-term efficacy requires further validation.
Humans ; Pulpotomy ; Tooth Fractures/surgery* ; Child ; Prospective Studies ; Male ; Female ; Tooth Root/injuries* ; Tooth Crown/injuries* ; Treatment Outcome ; Incisor/injuries* ; Child, Preschool

This report presents a case of a 9-year-old child with a complicated crown-root fracture of the maxillary central incisor, accompanied with a root fracture. The treatment strategy was minimally invasive, focusing on vital pulp preservation, root fracture recovery, and crown restoration. The fractured crown was reattached using resin short posts to enhance retention, resulting in aesthetic and functional restoration of the anterior teeth. A 2-year follow-up revealed favorable clinical and radiographic outcomes.
Humans ; Child ; Tooth Fractures/therapy* ; Tooth Root/injuries* ; Incisor/injuries* ; Tooth Crown/injuries* ; Post and Core Technique ; Dental Restoration, Permanent/methods* ; Maxilla

Dental trauma is one of the relatively common emergencies in clinical dental practice, with a high incidence rate, and the maxillary central incisors are the most frequently affected. This article reports a case of a 17-year-old female patient who suffered traumatic complete avulsion of teeth 11 and 21, with tooth 21 lost after avulsion. The prognosis for replantation was poor due to the absence of the buccal alveolar bone wall of tooth 11. Therefore, tooth 11 was treated with extracorporeal root canal therapy and then replanted into the alveolar socket of tooth 21, which had better conditions, followed by elastic splint fixation. After 20 months of follow-up observation, the affected tooth maintained a stable functional position, with no periapical inflammation or ankylosis observed. Subsequently, delayed implant restoration at the site of tooth 11 was performed, ultimately achieving a favorable treatment outcome. This case may provide new insights and references for future clinical practices in tooth replantation.
Humans ; Female ; Tooth Replantation/methods* ; Incisor/injuries* ; Adolescent ; Tooth Avulsion/therapy* ; Maxilla ; Root Canal Therapy

The accidental displacement of tooth roots into the mandibular canal is a serious complication during tooth extractions in oral and maxillofacial surgery, often resulting in direct damage to the structural and functional integrity of the inferior alveolar neurovascular bundle (IANB). This article reviews the anatomical features of the mandibular canal, the IANB, and adjacent tooth roots; identifies high-risk factors and anatomically vulnerable sites for root displacement; and outlines the clinical manifestations and radiographic characteristics of intraoperative root intrusion into the mandibular canal. Furthermore, management principles, surgical approaches and techniques, inferior alveolar nerve injury treatment, and prognostic considerations are discussed. The aim of this review is to provide a comprehensive clinical reference for improving surgical outcomes, and reducing postoperative complications.
Humans ; Tooth Extraction/adverse effects* ; Mandible/surgery* ; Tooth Root ; Mandibular Nerve/anatomy & histology* ; Postoperative Complications/prevention & control* ; Intraoperative Complications ; Mandibular Nerve Injuries/etiology*

Dental trauma is a common oral condition in children. For single-type trauma to young permanent teeth, timely treatment often results in a high survival rate for both the teeth and the pulp. However, in cases of complex dental trauma or when supernumerary teeth are impacted near the apex of the injured tooth, the prognosis is less predictable. This article reports a case of root fracture in an immature maxillary permanent central incisor combined with impacted supernumerary tooth in the apical region. After supernumerary tooth extraction and pulp revascularization therapy, the case demonstrated a good treatment outcome over a nearly 10-year follow-up period.
Child ; Humans ; Incisor/injuries* ; Maxilla ; Tooth Extraction ; Tooth Fractures/complications* ; Tooth Root/injuries* ; Tooth, Impacted/surgery* ; Tooth, Supernumerary/surgery*

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

The biomolecular mechanisms that regulate tooth root development and odontoblast differentiation are poorly understood. We found that Atp6i deficient mice (Atp6i^-/-) arrested tooth root formation, indicated by truncated Hertwig's epithelial root sheath (HERS) progression. Furthermore, Atp6i deficiency significantly reduced the proliferation and differentiation of radicular odontogenic cells responsible for root formation. Atp6i^-/- mice had largely decreased expression of odontoblast differentiation marker gene expression profiles (Col1a1, Nfic, Dspp, and Osx) in the alveolar bone. Atp6i^-/- mice sample RNA-seq analysis results showed decreased expression levels of odontoblast markers. Additionally, there was a significant reduction in Smad2/3 activation, inhibiting transforming growth factor-β (TGF-β) signaling in Atp6i^-/- odontoblasts. Through treating pulp precursor cells with Atp6i^-/- or wild-type OC bone resorption-conditioned medium, we found the latter medium to promote odontoblast differentiation, as shown by increased odontoblast differentiation marker genes expression (Nfic, Dspp, Osx, and Runx2). This increased expression was significantly blocked by anti-TGF-β1 antibody neutralization, whereas odontoblast differentiation and Smad2/3 activation were significantly attenuated by Atp6i^-/- OC conditioned medium. Importantly, ectopic TGF-β1 partially rescued root development and root dentin deposition of Atp6i^-/- mice tooth germs were transplanted under mouse kidney capsules. Collectively, our novel data shows that the prevention of TGF-β1 release from the alveolar bone matrix due to OC dysfunction may lead to osteopetrosis-associated root formation via impaired radicular odontoblast differentiation. As such, this study uncovers TGF-β1 /Smad2/3 as a key signaling pathway regulating odontoblast differentiation and tooth root formation and may contribute to future therapeutic approaches to tooth root regeneration.
Female ; Animals ; Mice ; Transforming Growth Factor beta1 ; Odontoblasts ; Culture Media, Conditioned ; Cell Differentiation ; Signal Transduction ; Disease Models, Animal ; Tooth Root

Tooth root development involves intricate spatiotemporal cellular dynamics and molecular regulation. The initiation of Hertwig's epithelial root sheath (HERS) induces odontoblast differentiation and the subsequent radicular dentin deposition. Precisely controlled signaling pathways modulate the behaviors of HERS and the fates of dental mesenchymal stem cells (DMSCs). Disruptions in these pathways lead to defects in root development, such as shortened roots and furcation abnormalities. Advances in dental stem cells, biomaterials, and bioprinting show immense promise for bioengineered tooth root regeneration. However, replicating the developmental intricacies of odontogenesis has not been resolved in clinical treatment and remains a major challenge in this field. Ongoing research focusing on the mechanisms of root development, advanced biomaterials, and manufacturing techniques will enable next-generation biological root regeneration that restores the physiological structure and function of the tooth root. This review summarizes recent discoveries in the underlying mechanisms governing root ontogeny and discusses some recent key findings in developing of new biologically based dental therapies.
Female ; Humans ; Tooth Root/metabolism* ; Odontogenesis ; Epithelial Cells ; Cell Differentiation ; Biocompatible Materials/metabolism*