MicroRNAs (miRs) and Hox transcription factors have decisive roles in postnatal bone formation and homeostasis. In silico analysis identified extensive interaction between HOXA cluster mRNA and microRNAs from the miR-23a cluster. However, Hox regulation by the miR-23a cluster during osteoblast differentiation remains undefined. We examined this regulation in preosteoblasts and in a novel miR-23a cluster-knockdown mouse model. Overexpression and knockdown of the miR-23a cluster in preosteoblasts decreased and increased, respectively, the expression of the proteins HOXA5, HOXA10, and HOXA11; these proteins’ mRNAs exhibited significant binding with the miR-23a cluster miRNAs, and miRNA-3’UTR-reporter assays confirmed repression. Importantly, during periods correlating with development and differentiation of bone cells we found an inverse pattern of expression between HoxA factors and members of the miR-23a cluster. HOXA5 and HOXA11 bound to bone-specific promoters, physically interacted with transcription factor RUNX2, and regulated bone-specific genes. Depletion of HOXA5 or HOXA11 in preosteoblasts also decreased cellular differentiation. Additionally, stable overexpression of the miR-23a cluster in osteoblasts decreased the recruitment of HOXA5 and HOXA11 to osteoblast gene promoters, significantly inhibiting histone H3 acetylation. Heterozygous miR-23a cluster knockdown female mice (miR-23a Cl^WT/ZIP) had significantly increased trabecular bone mass when compared to wild type (WT) mice. Furthermore, miR-23a cluster­­ knockdown in calvarial osteoblasts of these mice increased the recruitment of HOXA5 and HOXA11, with a substantial enrichment of promoter histone H3 acetylation. Taken together, these findings demonstrate that the miR-23a cluster is required for maintaining stage-specific HoxA factor expression during osteogenesis.

Objectives: This study observed whether changes in diagnosis caused by analysis of three-dimensional images can lead to alterations in the treatment plans of impacted lower third molars (ILTMs). Methods: Sets of panoramic (PAN) – cone beam computed tomography (CBCT) of 218 patients were assessed for ILTM classification, contact with mandibular canal, contact and resorption of the lower second molar (LSM), intraoperative planning and post-operative expectations. Results: Percentage agreement and McNemar test compared PAN vs CBCT assessments. Logistic regression analyzed the dependency of change in surgical planning considering the changes in diagnostic features; descriptive statistics was used to observe the expectation of post-operative complications and paresthesia. Differences were found between PAN vs CBCT for classification of impaction and positioning, LSM relationship, choice for crown and root sectioning and expectation of post-operative complications (all with p < 0.001). Logistic regression indicated that the change in diagnosis caused by CBCT examination did not change the clinical decision to extract ILTM but altered the planning of intraoperative steps such as osteotomy, crown sectioning and relaxing incision. The expectation of post-operative complications decreased when professionals planned the ILTM removal using tri-dimensional images. Conclusions: We concluded that changes in the diagnosis after CBCT examination can lead to alterations in the treatment plan of impacted lower third molar.

An unusual case of an impacted right maxillary third molar that was accidentally displaced into the maxillary sinus during exodontia and was surgically retrieved almost 2 years later is described. The tooth was removed under general anesthesia, after maxillary sinus exposure through Caldwell-Luc approach. Postoperative recovery was uneventful. Six months after the retrieval surgery, the maxillary sinus was completely healed and the patient did not present any complaint.