Factors affecting treatment duration of labial inversely impacted maxillary central incisors.

INTRODUCTION: A labial inversely impacted maxillary central incisor is a relatively rare occurrence. The crown of the tooth is directed upward, and its palatal aspect is facing labially. This typical orientation can be the result of trauma to the deciduous incisor transmitted to the palatal side of the crown of the permanent incisor. Labial inversely impacted maxillary central incisors are most commonly combined with labial-lingual root dilacerations. The aim of this study was to examine factors that affect the surgical-orthodontic treatment duration of labial inversely impacted maxillary central incisors. METHOD: The records of 35 consecutively treated patients were retrospectively evaluated. Cone-beam computed tomography images were taken before treatment, and factors affecting treatment time, including age, length, crown-root angle, crown height and depth, angle of inversion, rotation to axial plane, and distance and angle to midline, were measured using Dolphin Imaging software (version 11.8; Patterson Supply, St Paul, Minn). Treatment duration was evaluated for each patient, and logistic regression analyses were applied. RESULTS: The 15 boys and 20 girls had a mean age 8.36 ± 1.36 years. The mean orthodontic traction duration was 11.28 ± 3.08 months. Multiple regression analyses indicated that factors resulting in a longer duration were age (ß = 0.779; P = 0.043), crown height (ß = 0.344; P = 0.007), crown-root angle (ß = -0.037; P = 0.018), and tooth length (ß = -0.623; P = 0.038). CONCLUSIONS: Surgical-orthodontic correction of labial inversely impacted maxillary incisors requires an average of 1 year. Assessments of age, crown height, root dilaceration, and length of incisor can help the orthodontist to better predict treatment duration during consultations with patients and parents.

Survival of labial inversely impacted maxillary central incisors: A retrospective cone-beam computed tomography 2-year follow-up.

INTRODUCTION: The aim of this study was to analyze the development and stability of roots and alveolar bone in orthodontically treated labial inversely impacted maxillary central incisors in a long-term follow-up by cone-beam computed tomography. Comparisons were made between the labial inversely impacted maxillary central incisors after treatment and normally erupted mature contralateral incisors. METHODS: The sample consisted of 12 participants, with a mean age of 7.80 ± 0.91 years. Cone-beam computed tomography scanning data at the completion of treatment and the long-term follow-up were available for each participant.The mean length of follow-up was 24.57 ± 4.33 months. Root length, crown height, root canal width, labial/lingual alveolar bone vertical loss, and bone thickness of the impacted and contralateral incisors were measured with the SimPlant Pro program (version 13.0; Materialise Dental, Leuven, Belgium). RESULTS: In the follow-up, the root lengths of both the labial inversely impacted dilacerated maxillary central incisors (10.99 ± 1.96 mm) and the contralateral mature maxillary central incisors (11.65 ± 1.37 mm) were significantly longer than at posttreatment (8.37 ± 1.74 mm and 9.81 ± 1.65 mm, respectively). The root canal widths of the impacted and contralateral incisors were significantly narrower during the follow-up. The size of the angle between the long axis of the crown and apical third of the root decreased significantly. The lingual alveolar bone loss of the impacted incisors was greater than that of the contralateral incisors. The labial bone thickness at the apex of the impacted incisors increased significantly during the follow-up period. CONCLUSIONS: The treated labial inversely impacted maxillary central incisors had continuous and similar growth as did the mature contralateral incisors in the follow-up period. The roots had an increase in length and a change in direction of the apex, with a relatively stable condition of the surrounding alveolar bone. Neither the labial inversely impacted maxillary central incisors nor the contralateral incisors had further alveolar bone loss.

Silk fibroin/chitosan scaffold: preparation, characterization, and culture with HepG2 cell.

Tissue engineering requires the development of three-dimensional water-stable scaffolds. In this study, silk fibroin/chitosan (SFCS) scaffold was successfully prepared by freeze-drying method. The scaffold is water-stable, only swelling to a limited extent depending on its composition. Fourier Transform Infrared (FTIR) spectra and X-Ray diffraction curves confirmed the different structure of SFCS scaffolds from both chitosan and silk fibroin. The homogeneous porous structure, together with nano-scale compatibility of the two naturally derived polymers, gives rise to the controllable mechanical properties of SFCS scaffolds. By varying the composition, both the compressive modulus and compressive strength of SFCS scaffolds can be controlled. The porosity of SFCS scaffolds is above 95% when the total concentration of silk fibroin and chitosan is below 6 wt%. The pore sizes of the SFCS scaffolds range from 100 microm to 150 microm, which can be regulated by changing the total concentration. MTT assay showed that SFCS scaffolds can promote the proliferation of HepG2 cells (human hepatoma cell line) significantly. All these results make SFCS scaffold a suitable candidate for tissue engineering.