Na-Rae Choi

The factors that influence postoperative stability of the dental implants in posterior edentulous maxilla

BackgroundAll clinicians are aware of the difficulty of installing a dental implant in posterior maxilla because of proximate position of maxillary sinus, insufficient bone width, and lower bone density. This study is to examine which factors will make the implantation in the posterior maxilla more difficult, and which factors will affect the postoperative implant stability in this region.MethodsFive hundred seventy-three fixtures on the maxilla posterior were included for this study from all the patients who underwent an installation of the dental implant fixture from January 2010 to December 2014 at the Department of Oral and Maxillofacial Surgery in Pusan National University Dental Hospital (Yangsan, Korea). The postoperative implant stability quotient (ISQ) value, fixture diameter and length, presence of either bone graft or sinus lift, and graft material were included in the reviewed factors. The width and height of the bone bed was assessed via preoperative cone beam CT image analysis. The postoperative ISQ value was taken just before loading by using the OsstellTM mentor® (Integration Diagnostics AB, Gothenburg, Sweden). The t test and ANOVA methods were used in the statistical analysis of the data.ResultsMean ISQ of all the included data was 79.22. Higher initial bone height, larger fixture diameter, and longer fixture length were factors that influence the implant stability on the posterior edentulous maxilla. On the other hand, the initial bone width, bone graft and sinus elevation procedure, graft material, and approach method for sinus elevation showed no significant impact associated with the implant stability on the posterior edentulous maxilla.ConclusionsIt is recommended to install the fixtures accurately in a larger diameter and longer length by performing bone graft and sinus elevation.

Mandibular reconstruction with a ready-made type and a custom-made type titanium mesh after mandibular resection in patients with oral cancer

BackgroundAfter the resection at the mandibular site involving oral cancer, free vascularized fibular graft, a type of vascularized autograft, is often used for the mandibular reconstruction. Titanium mesh (T-mesh) and particulate cancellous bone and marrow (PCBM), however, a type of non-vascularized autograft, can also be used for the reconstruction. With the T-mesh applied even in the chin and angle areas, an aesthetic contour with adequate strength and stable fixation can be achieved, and the pores of the mesh will allow the rapid revascularization of the bone graft site. Especially, this technique does not require microvascular training; as such, the surgery time can be shortened. This advantage allows older patients to undergo the reconstructive surgery.Case presentationReported in this article are two cases of mandibular reconstruction using the ready-made type and custom-made type T-mesh, respectively, after mandibular resection. We had operated double blind peer-review process. A 79-year-old female patient visited the authors’ clinic with gingival swelling and pain on the left mandibular region. After wide excision and segmental mandibulectomy, a pectoralis major myocutaneous flap was used to cover the intraoral defect. Fourteen months postoperatively, reconstruction using a ready-made type T-mesh (Striker-Leibinger, Freibrug, Germany) and iliac PCBM was done to repair the mandible left body defect.Another 62-year-old female patient visited the authors’ clinic with pain on the right mandibular region. After wide excision and segmental mandibulectomy on the mandibular squamous cell carcinoma (SCC), reconstruction was done with a reconstruction plate and a right fibula free flap. Sixteen months postoperatively, reconstruction using a custom-made type T-mesh and iliac PCBM was done to repair the mandibular defect after the failure of the fibula free flap. The CAD-CAM T-mesh was made prior to the operation.ConclusionsIn both cases, sufficient new-bone formation was observed in terms of volume and strength. In the CAD-CAM custom-made type T-mesh case, especially, it was much easier to fix screws onto the adjacent mandible, and after the removal of the mesh, the appearance of both patients improved, and the neo-mandibular body showed adequate bony volume for implant or prosthetic restoration.

Recombinant human bone morphogenic protein-2 Induces the Differentiation and Mineralization of Osteoblastic Cells Under Hypoxic Conditions via Activation of Protein Kinase D and p38 Mitogen-Activated Protein Kinase Signaling Pathways

Hypoxia suppresses osteoblastic differentiation and the bone-forming capacity. As the leading osteoinductive growth factor used clinically in bone-related regenerative medicine, recombinant human bone morphogenic protein-2 (rhBMP-2) has yielded promising results in unfavorable hypoxic clinical situations. Although many studies have examined the effects of rhBMP-2 on osteoblastic differentiation, mineralization and the related signaling pathways, those of rhBMP-2 on osteoblastic cells remain unknown, particularly under hypoxic conditions. Therefore, this study was conducted under a 1% oxygen tension to examine the differentiating effects of rhBMP-2 on osteoblastic cells under hypoxia. rhBMP-2 could also induce the differentiation and mineralization of Osteoblastic (MC3T3-E1) cells under 1% hypoxic conditions. rhBMP-2 could also induce the differentiation and mineralization of MC3T3-E1 cells under 1% hypoxic conditions. rhBMP-2 increased the alkaline phosphatase {ALP} activity in a time dependent manner, and expression of ALP, collagen type-1 (Col-1) and osteocalcin (OC) mRNA were up-regulated significantly in a time- and concentration-dependent manner. In addition, the area of the mineralized nodules increased gradually in a concentration-dependent manner. Western blot analysis, which was performed to identify the signaling pathways underlying rhBMP-2-induced osteoblastic differentiation under hypoxic conditions, showed that rhBMP-2 significantly promoted the phosphorylation of the p38 mitogen-activated protein kinase (MAPK) in a time-dependent manner. A pretreatment with SB203580, a p38 MAPK inhibitor, inhibited the rhBMP-2-mediated differentiation and mineralization. Moreover, the phosphorylation of p38 induced by rhBMP-2 was inhibited in response to a pretreatment of the cells with Go6976, a protein kinase D {PKD) inhibitor. These findings suggest that rhBMP-2 induces the differentiation and mineralization of MC3T3-E1 cells under hypoxic conditions via activation of the PKD and p38 MAPK signaling pathways.

Corrigendum: Relationship between disease stage and renal function in bisphosphonate-related osteonecrosis of the jaw

[This corrects the article on p. 16 in vol. 43, PMID: 28280705.].

Relationship between disease stage and renal function in bisphosphonate-related osteonecrosis of the jaw

Objectives Bisphosphonate is the primary cause of bisphosphonate-related osteonecrosis of the jaw (BRONJ). Bisphosphonates are eliminated from the human body by the kidneys. It is anticipated that bisphosphonate levels in the body will increase if the kidney is in a weak state or if there is systemic disease that affects kidney function. The aim of this study was to analyze the relevance of renal function in the severity of BRONJ. Materials and Methods Ninety-three patients diagnosed with BRONJ in Pusan National University Dental Hospital from January 2012 to December 2014 were included in this study. All patients underwent a clinical exam, radiographs, and serologic lab test, including urine analysis. The patients medical history was also taken, including the type of bisphosphonate drug, the duration of administration and drug holiday, route of administration, and other systemic diseases. In accordance with the guidelines of the 2009 position paper of American Association of Oral and Maxillofacial Surgeons, the BRONJ stage was divided into 4 groups, from stage 0 to 3, according to the severity of disease. IBM SPSS Statistics version 21.0 (IBM Co., USA) was used to perform regression analysis with a 0.05% significance level. Results BRONJ stage and renal factor (estimated glomerular filtration rate) showed a moderate statistically significant correlation. In the group with higher BRONJ stage, the creatinine level was higher, but the increase was not statistically significant. Other factors showed no significant correlation with BRONJ stage. There was a high statistically significant correlation between BRONJ stage and ‘responder group’ and ‘non-responder group,’ but there was no significant difference with the ‘worsened group.’ In addition, the age of the patients was a relative factor with BRONJ stage. Conclusion With older age and lower renal function, BRONJ is more severe, and there may be a decrease in patient response to treatment.

Erratum to: The effects on dermal wound healing using novel peptide modified by bone morphogenic protein-2

New alternatives to growth factors, such as transforming growth factor beta (TGF-β), epidermal growth factor (EGF), fibroblast growth factor (FGF) and bone morphogenetic proteins (BMP), for wound healing have been devised and investigated to maintain their biological properties, as well as to reduce their complicated adverse effects. In this study, we have focused on OP10 peptide modified from BMPs which regulates a variety of cellular processes, such as proliferation, differentiation, bone/cartilage morphogenesis, apoptosis, and wound healing. The wound healing process involves multiple physiological processes, such as proliferation and migration of dermal fibroblasts and epidermal keratinocytes. These processes play an important role in collagen production and the regulation of elastin levels in dermal tissue regeneration. In order to evaluate the promotion of cell proliferation and migration using OP10, MTT and scratch assays were carried out using normal dermal human fibroblast (NHDF). OP10 promoted proliferation and migration of NHDFs similar to those found with FGF. OP10 was focused on this study and was further investigated for its wound skin regeneration capacity and compared to FGF, by mRNA and protein expression. OP10 was found to increase the protein expression of procollagen and the mRNA level of Type I collagen, to levels similar or even higher than that found with FGF. OP10 inhibits not only matrix metalloproteinase (MMP)-1 expression but also elastase secretion, higher than the effects seen with FGF. Based on these results, we conclude that OP10 plays a role in the regeneration of damaged skin by activating dermal fibroblasts in vitro and may have further potential as wound repair or cosmetic materials for wrinkle improvement.

The effects on dermal wound healing using novel peptide modified by bone morphogenic protein-2

New alternatives to growth factors, such as transforming growth factor beta (TGF-β), epidermal growth factor (EGF), fibroblast growth factor (FGF) and bone morphogenetic proteins (BMP), for wound healing have been devised and investigated to maintain their biological properties, as well as to reduce their complicated adverse effects. In this study, we have focused on OP10 peptide modified from BMPs which regulates a variety of cellular processes, such as proliferation, differentiation, bone/cartilage morphogenesis, apoptosis, and wound healing. The wound healing process involves multiple physiological processes, such as proliferation and migration of dermal fibroblasts and epidermal keratinocytes. These processes play an important role in collagen production and the regulation of elastin levels in dermal tissue regeneration. In order to evaluate the promotion of cell proliferation and migration using OP10, MTT and scratch assays were carried out using normal dermal human fibroblast (NHDF). OP10 promoted proliferation and migration of NHDFs similar to those found with FGF. OP10 was focused on this study and was further investigated for its wound skin regeneration capacity and compared to FGF, by mRNA and protein expression. OP10 was found to increase the protein expression of procollagen and the mRNA level of Type I collagen, to levels similar or even higher than that found with FGF. OP10 inhibits not only matrix metalloproteinase (MMP)-1 expression but also elastase secretion, higher than the effects seen with FGF. Based on these results, we conclude that OP10 plays a role in the regeneration of damaged skin by activating dermal fibroblasts in vitro and may have further potential as wound repair or cosmetic materials for wrinkle improvement.