Objectives: To evaluate the condyle-fossa relationship in adolescents with various skeletal patterns using cone-beam computed tomography (CBCT). Materials and Methods: CBCT images obtained in 120 adolescent patients were used for this study. The patients were divided into 3 groups according to 3 criteria: (1) age (early, middle, and late adolescence); (2) facial height ratio or Jarabak quotient (hyperdivergent, normodivergent, and hypodivergent); and (3) ANB classification (Class I, Class II, and Class III). Temporomandibular joint space (TMJS: AS, anterior space; SS, superior space; PS, posterior space; MS, medial space; LS, lateral space), width and depth of the condyle (MLT, mediolateral thickness; APT, anteroposterior thickness), articular slope (ArS) and vertical height of the fossa (VHF) were measured and compared using CBCT. Results: Differences in condyle-fossa relationships were not significantly different between male and female adolescents, but were significantly different (P < .05) between left and right sides. The mean values showed no statistical differences according to age and skeletal pattern. Most measurements in the sagittal view showed that SS was the greatest, and the mean ratio of AS to SS to PS was 1.00 to 1.27 to 1.19, respectively. The mean values of coronal MS and LS were not significantly different. Conclusions: There were almost no statistical differences in the TMJS in adolescents across various factors except between left and right sides.

When inserting OMIs, increasing the distance from the OMI to the root surface will significantly improve success rates.

ObjectiveThe purpose of this study was to determine whether predicting maturation of the midpalatal suture is possible by classifying its morphology on cone-beam computed tomography (CBCT) images and to investigate relationships with other developmental age indices.MethodsThe morphology of the midpalatal suture was assessed by using CBCT images of 99 patients. Axial plane images of the midpalatal suture were classified into five stages according to the classification scheme. To make the assessment more accurate, the morphology and fusion of the midpalatal suture were additionally investigated on coronal cross-sectional planar images and volume-rendered images. Bone age was evaluated using the hand and wrist method (HWM) and cervical vertebrae method (CVM); dental age (Hellman's index), sex, and chronological age were also assessed. To evaluate relationships among variables, Spearman's rho rank test was performed along with crosstabs using contingency coefficients.ResultsThe HWM and CVM showed strong correlations with the maturation stage of the midpalatal suture, while other indices showed relatively weak correlations (p < 0.01). Through crosstabs, the HWM and CVM showed high association values with CBCT stage; the HWM demonstrated slightly higher values (p < 0.0001). Based on the HWM, the midpalatal suture was not fused until stage 6 in both sexes.ConclusionsAmong developmental age indices, the HWM and CVM showed strong correlations and high associations, suggesting that they can be useful in assessing maturation of the midpalatal suture.

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ObjectiveThe purpose of this study was to investigate factors influencing the success rate of orthodontic microimplants (OMIs) using panoramic radiographs (PRs).MethodsWe examined 160 OMIs inserted bilaterally in the maxillary buccal alveolar bone between the second premolars and first molars of 80 patients (51 women, 29 men; mean age, 18.0 ± 6.1 years) undergoing treatment for malocclusion. The angulation and position of OMIs, as well as other parameters, were measured on PRs. The correlation between each measurement and the OMI success rate was then evaluated.ResultsThe overall success rate was 85.0% (136/160). Age was found to be a significant predictor of implant success (p < 0.05), while sex, side of placement, extraction, and position of the OMI tip were not significant predictors (p > 0.05). The highest success rate was observed for OMIs with tips positioned on the interradicular midline (IRML; central position). Univariate analyses revealed that the OMI success rate significantly increased with an increase in the OMI length and placement height of OMI (p = 0.001). However, in simultaneous analyses, only length remained significant (p = 0.027). Root proximity, distance between the OMI tip and IRML, interradicular distance, alveolar crest width, distance between the OMI head and IRML, and placement angle were not factors for success. Correlations between the placement angle and all other measurements except root proximity were statistically significant (p < 0.05).ConclusionsOur findings suggest that OMIs positioned more apically with a lesser angulation, as observed on PRs, exhibit high success rates.

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Nitric oxide (NO), synthesized from L-arginine by a family of constitutive and inducible NO synthases (iNOS), is a small, diffusible, diatomic, highly reactive molecule with a variety of cellular functions in all mammalian cells. 1) Recently, it was shown that NO plays an important role in stem cell proliferation and differentiation. It has been reported that, at physiological concentrations, NO functions as a negative regulator of stem/progenitor cell proliferation and is critical to the initiation of cell differentiation.2,3) NO also promotes bone and chondrocyte terminal differentiation ; stimulates preadipocyte differentiation in rat 6) ; and mediates osteoblastic differentiation.7) In addition, NO synthase inhibitors have been shown to arrest differentiation toward a cardiac phenotype in mouse embryonic stem cells; differentiation is rescued by NO donors. 8) In contrast, NO donor sodium nitroprusside (SNP) inhibits mineralization in the mouse chondrocyte-like ATDC5 cell line. 9) However, whether NO can affect the differentiation of periodontal ligament (PDL) cells is unknown.The PDL is a non-mineralized connective tissue which surrounds the tooth and exhibits osteoblast-like features, such as high alkaline phosphatase (ALP) activity and expression of osteonectin (ON), bone sialoprotein (BSP), osteocalcin (OC), and osteopontin (OPN). The cells that compose the PDL are capable of differentiating into osteoblasts or cementoblasts.10) Moreover, PDL cells have demonstrated stem cell properties such as self-renewal, clonogenicity, and multitissue differentiation potential.11) In addition, PDL cells can differentiate in response to a variety of extracellular stimuli, serving either to maintain homeostasis or to remodel, repair, and regenerate the surrounding hard tissue.12) Recently, increased NO production during osteogenic differentiation has been reported in human PDL cells, 13) but the role of NO in osteoblastic differentiation of these cells requires further investigation.Heme oxygenase (HO) is the rate-limiting enzyme involved in the catabolism of heme, yielding equimolar quantities of carbon monoxide (CO), free iron, and biliverdin; the latter two compounds are converted to ferritin and bilirubin, respectively. 14) One of three mammalian HO isoforms, HO-1 (also called heat shock protein 32), is a stress-responsive protein induced by various agents and is involved in a variety of regulatory and protective mechanisms in cells. 15,16) We previously reported that HO-1 is induced by pro-inflammatory cytokines, NO, substance P, hydrogen peroxide, and mechanical stress, [17][18][19][20][21][22][23] and that it may play a cytoprotective role in human pulp and PDL cells. However, HO-1-mediated NOinductive effects of osteoblastic differentiation in PDL cells has not yet been reported.Understanding the mechanisms that regulate osteogenic differentiation in human PDL cells will have important implications for the development of new therapeutic strategies in periodontal defects. This study aimed to investigate whether h...

Objective: To systematically review the effects of cortical bone thickness (CBT) and bone mass density (BMD) on miniscrew success rates. Methods: MEDLINE, the Cochrane Library and Scopus were searched up to June 2020. Of a total of 5734 articles, seven studies were finally selected for the review. Results: The overall mean success rate weighted by the number of miniscrews was 87.21% (89.87% in the maxilla and 79.24% in the mandible). There was a significantly higher success rate for miniscrews placed in the maxilla compared with those in the mandible (P < .05). CBT showed small positive effect on the success rate of the miniscrews although it failed to reach a statistical significance. The cortical BMD had a minimal effect on the success of the miniscrews. The cancellous BMD demonstrated a very strong effect on the success of the miniscrews in the maxilla, whereas it showed a moderately negative effect in the mandible. Limitations: Because of the small number and clinical heterogeneity of the included studies, the results should be interpreted with caution. Further randomized clinical studies with a large sample size are recommended.