The root of late-dental-age labial inversely impacted maxillary central incisors (LIIMCIs) typically develops to severe dilacerated morphology. Therefore, reliable posttreatment periodontal estimates of orthodontic treatment prognosis would be critical to the treatment value of impacted incisors. This study aims to analyze further changes in dimensions of the alveolar bone following the closed-eruption treatment of late-dental-age dilacerated LIIMCIs. Cone beam computed tomography (CBCT) scanning data of 16 patients with unilateral dilacerated late-dental-age LIIMCIs were collected, including the pretreatment (T1) and at the 2.23 ± 0.78 years follow-up stage (T2) respectively. Patients underwent closed-eruption treatments to bring the impacted incisor into the dental arch. Dolphin imaging software was used to measure alveolar bone height labially, palatally, and proximally to the site at T1 and T2, as well as alveolar bone thicknesses at 0, 2, 4, 6 and 8 mm below the initial measurement plane (IMP). The alveolar bone heights on the impacted and contralateral sides increased from T1 to T2 (p < 0.05). Alveolar bone growth on both sides had no significant difference. In T2, the mean values of labial and distal alveolar heights on the contralateral sides were greater than on the impacted sides (p < 0.05). The mean values of total alveolar bone thicknesses on the impacted sides in T1 were significantly smaller than those on the contralateral sides in IMP-0, 2, 4, 6, 8 (p < 0.05). The total thicknesses on the impacted sides in T2 increased and were significantly greater than on the contralateral sides (p < 0.05), except for the thickness in IMP-0. The closed-eruption treatment of dilacerated late-dental-age LIIMCIs results in no significant changes to alveolar bone height, except on the labial and distal sides, with increased alveolar bone thickness, suggesting that this approach may be viable first choice therapy for non-extraction orthodontic cases.

OBJECTIVE: 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.
目的: 总结既往上前牙区埋伏牙开放式牵引方法的基础上，报告一种基于牙囊的软组织处理技术，并监测治疗后埋伏牙牙根长度变化和牙槽骨丢失量，探讨牙囊在埋伏上颌中切牙唇侧微创开放式牵引中的重要作用。方法: 选择单侧唇侧埋伏上颌中切牙并采用开放式牵引技术治疗的患者，将埋伏中切牙纳入试验组，将对侧未受影响的中切牙纳入对照组。在外科手术暴露埋伏上颌中切牙时，利用埋伏牙周围的牙囊组织进行术区软组织管理，最大程度地保存埋伏牙周围软硬组织量。在埋伏上颌中切牙牵引至牙合平面后，记录其牙长、根长、骨丢失量、骨厚度等测量值。结果: 成功牵引了17例单侧唇侧埋伏上颌中切牙。牵引后试验组与对照组之间，牙长、根长、唇侧骨丢失量的差异有统计学意义（P<0.05），唇-腭釉牙骨质界处宽度、腭侧骨丢失量、唇侧骨厚度、腭侧骨厚度、根尖牙槽骨厚度的差异无统计学意义（P>0.05）。结论: 在外科手术暴露唇侧埋伏上颌中切牙时，本方法利用埋伏牙周围的牙囊组织进行术区软组织管理，最大程度地保存埋伏牙周围软硬组织量，尽可能在牵引萌出后获得更好的美学效果和健康的牙周组织。.

BACKGROUND: Morphological anomalies of teeth, including talon cusp, dens evaginatus, gemination, fusion, concrescence, root dilaceration, and taurodontism, always involve changes in the enamel, cementum and dentin. Diagnosing concrescent teeth through routine clinical examination alone is difficult, and most cases of concrescence are found accidentally during extraction. A definite preoperative diagnosis of concrescence would contribute to a better treatment plan and fewer undesirable complications.
METHODS: A 47-year-old woman who complained of left maxillary first molar loss for half a year presented to our department seeking treatment by dental implant restoration. Panoramic radiography and cone-beam computed tomography (CBCT) showed an unclear boundary between the distal root of the second molar and the mesial root of the third molar. The teeth were extracted under local anesthesia, and a definite diagnosis of concrescence was made by histopathological examination.
CONCLUSIONS: CBCT is a useful tool for diagnosing and planning the management of tooth concrescence and may be beneficial for reducing unnecessary complications.

Herein, we described the multidisciplinary treatment of a mixed dentition patient with impacted maxillary right central incisor and adjacent compound odontoma. In contrast to conventional treatment procedures, orthodontic traction was first performed for the affected tooth in this case, followed by resection of the odontoma. The odontoma did not shift after eruption of the incisor and was safely removed after alignment of the impacted tooth. No root resorption, gingival recession or bone defect occurred in this case. These results demonstrated that the orthodontic force can break the connection between the impacted tooth and the odontoma. The increased distance between the impacted tooth and odontoma may facilitate removal of the odontoma. Adhesion between the soft tissue capsule of odontoma and the dental follicle, rather than blocking the tooth, may play a role in tooth impaction.

BACKGROUND: Kissing molars (KMs) are a scarcely reported form of molar impaction in which the occlusal surfaces contact each other within a single dental follicle and the roots point in opposite directions. The direction of KMs impaction is generally tilted. KMs with vertical direction impaction have not been reported in the literature.
METHODS: A 25-year-old female visited a dentist for right maxillary wisdom teeth extraction and was diagnosed with two vertically impacted KMs in the left mandible on panoramic radiography. After cone-beam computed tomography examination confirmed no secondary complication, the patient chose to undergo observation and regular follow-up. A literature review of KMs revealed that vertical impacted KMs are rare; high-quality evidence regarding their prevalence is still lacking. At present, the causality of KMs is controversial. In this study, we have tried to provide a detailed definition of KMs to allow an accurate evaluation of their prevalence and classification based on their impaction direction which may be related to their pathogenesis. The treatment plan of KMs depends on the condition and location of the affected teeth and associated complications; they may be either directly extracted or treated using a multidisciplinary approach including maxillofacial surgeons and orthodontists.
CONCLUSIONS: KMs are a rare clinical condition of impacted teeth with unclear pathogenesis. Vertically impacted KMs were seldom reported. Reasonable definition and classification of KMs can help in the understanding of their causes and prevalence.

OBJECTIVE: This retrospective study aimed to comprehensively delineate the epidemiological and 3-dimensional radiographic characteristics of non-third molar (non-M3) impacted teeth in a Chinese dental population.
METHODS: Patients with impacted teeth except for the third molar (ITEM3) were retrospectively screened via cone-beam CT images from 75,021 patients treated at our institution from June 2012 to December 2018. Demographic and clinical data of patients with ITEM3 were retrieved from medical records. CBCT coupled with 3-dimensional reconstruction was employed to characterize the radiographic features of ITEM3. Associations between these epidemiological, clinical, and radiographic features were further statistically analyzed.
RESULTS: Among 1975 eligible patients, 2467 ITEM3s were identified with a prevalence of 2.63% (1975/75,021). Females slightly outnumbered males with a ratio of 1.12:1. The majority of ITEM3 was single (1577, 79.85%) in the maxilla. The maxillary canine teeth were the most frequently impacted (52.45%), followed by maxillary incisors. The mesioangular position was the most common orientation (43.8%), followed by vertical and buccal-lingual orientations. The most frequently associated lesion was external root resorption of the adjacent tooth, which was significantly correlated with the morphology and position of the impacted tooth.
CONCLUSIONS: Most ITEM3 was single, mesioangular, found at maxillary canines, sometimes associated with diverse complications. Our data advance the current understanding of ITEM3 and offer insights into the management of this dental abnormality.
CONCLUSIONS: These findings are useful for clinicians to comprehensively understand the prevalence, radiographic features, and complications of non-M3 impacted teeth.

The present study aimed to report a technically improved operation on the surgical exposure of labially impacted maxillary canine, elaborating the management of soft tissue to achieve better aesthetic results, and post-treatment periodontal health.
Patients sought orthodontic treatment with unilateral labially impacted maxillary canines were selected in this study. The impacted teeth were assigned to the experimental group and contralateral unimpacted canines were assigned to the control group. The impacted canines were surgically exposed with dissected dental follicle (DF) stitching to muscle and mucosa surrounding the crowns. The gingival index (GI), probing depth (PD), the width of the keratinized gingiva (WKG), gingival scars (GS), bone loss (BL), and apical root resorption (ARR) were recorded after the removal of the fixed appliance. A two-sample t-test was used for independent samples for parametric variables.
A total of 24 patients with unilateral maxillary canine impaction were successfully treated. The outcomes of GI, WKG, GS, BL, and ARR did not indicate statistical significance between the experimental group and the control group.
The preservation of DF promotes soft tissue management in combined surgical and orthodontic treatment of labially impacted maxillary canine to achieve better periodontal status. Trial Registration Chinese Clinical Trial Registry ChiCTR2000029091, 2020-01-12.

It is a consensus that symptomatic impacted mandibular third molars (MTMs) need to be removed. Although the prophylactic extraction of asymptomatic impacted MTMs remains controversial. This study aims to investigate the effects of MTMs on themselves and adjacent teeth pathophysiology and provide the evidence for prophylactic extraction of impacted MTMs.
A retrospective study of panoramic radiographs of patients visited the Affiliated Stomatology Hospital of Guangzhou Medical University from April 2014 to May 2018 was conducted to investigate the dental and periodontal lesions in MTMs and adjacent mandibular second molars (MSMs), as well as the correlation of tooth lesion severity with patient age.
Among the 2650 impacted MTMs, 6.98% dental lesions and 37.81% periodontal lesions were found, as well as 24.63% dental lesions and 35.30% periodontal lesions in the distal of adjacent MSMs. 9.27%, 2.02%, 0.47%, and 13.33% dental lesions and 48.81%, 17.31%, 5.19%, and 10% periodontal lesions were observed in MTMs with mesioangular, horizontal, inverted and distoangular impaction types, respectively. For the adjacent MSMs, 31.98%, 11.82%, 1.94%, and 13.33% distal dental lesions and 45.74%, 16.95%, 2.91%, and 23.33% distal periodontal lesions were found in mesioangular, horizontal, inverted and distoangular impaction types, respectively. In mesioangular MTMs, the severity of the distal dental and periodontal lesions in the adjacent MSMs showed a high-positive correlation with patient age (P < 0.05) CONCLUSION: Early prophylactic extraction of MTMs with mesioangular-impaction and close monitoring of MTMs with horizontal/inverted-impaction could prevent impacted MTMs-associated lesions in MTMs/MSMs.

The aim of this study was to evaluate the aesthetics and outcome of autotransplantation of impacted canines unsuitable for orthodontic realignment using a combination of surgery with guided bone regeneration and orthodontic treatment. Ten severely impacted canines in nine consecutive patients (mean age 14.8 years) were included. The recipient mesiodistal space was created orthodontically and the recipient socket prepared using dental implant drills. Following transplantation, bone defects were grafted using guided bone regeneration, teeth were aligned and occlusions adjusted orthodontically. Patients were followed-up every 6 months for an average of 7.1 years (range 2-11 years). The mean pink aesthetic score was 13.33 ± 0.87. Pocket depths were less than 3 mm. Radiographic examination showed an uninterrupted periodontal space and lamina dura in seven cases, unclear periodontal space in two, and replacement resorption in one case. The analysis showed that canine transplantation combined with guided bone regeneration and orthodontic treatment gives acceptable and predictable aesthetic results.