Hong-In Shin

Zinc may increase bone formation through stimulating cell proliferation, alkaline phosphatase activity and collagen synthesis in osteoblastic MC3T3-E1 cells

Zinc is an essential trace element required for bone formation, however not much has been clarified yet for its role in osteoblast. We hypothesized that zinc would increase osteogenetic function in osteoblasts. To test this, we investigated whether zinc treatment enhances bone formation by stimulating osteoblast proliferation, bone marker protein alkaline phosphatase activity and collagen synthesis in osteoblastic MC3T3-E1 cells. MC3T3-E1 cells were cultured and treated with various concentrations of zinc (0, 1, 3, 15, 25 uM) along with a normal osteogenic medium (OSM) as control for 1, 5, 10 days. As measured by MTT assay for mitochondrial metabolic activity, cell proliferation was stimulated even at low zinc treatment (1-3 µM) compared to OSM, and it was stimulated in a zinc concentration-dependent manner during 5 and 10 days, with the most pronounced effect at 15 and 25 uM Zn. Cellular (synthesized) alkaline phosphatase (ALP) activity was increased in a zinc concentration-dependent manner, so did medium (secreted) ALP activity. Cellular collagen concentration was increased by zinc as time went by, therefore with the maximum zinc stimulatory effect in 10 days, and medium collagen concentration showed the same pattern even on 1 and 5 day. This zinc stimulatory effect of collagen synthesis was observed in cell matrix collagen staining. The study results imply that zinc can increase osteogenic effect by stimulating cell proliferation, ALP activity and collagen synthesis in osteoblastic cells.

New bone formation in the maxillary sinus without bone grafts.

Purpose:Various sinus augmentation procedures, using bone substitutes, have been used to place dental implants in the atrophic posterior maxilla. The aim of this article is to evaluate the possibility of new bone formation in the maxillary sinus without a bone graft. Materials:Ten patients without significant sinus pathosis were selected for this study. The bony window was prepared in the lateral wall using the ultrasonic piezoelectric bone surgery device (Surgybone, Silfradent srl, Sofia, Italy). The sinus membrane was elevated superiorly and implants were placed simultaneously to maintain the space under the sinus membrane for new bone formation. As the methods of sealing the lateral access window of the sinus, patients were divided into 2 groups. Nonresorbable membrane was used to seal the lateral access window of the maxillary sinus after implant placement in 5 cases (group A). Replaceable bony window was used to seal the lateral wall of the sinus in another 5 cases (group B). Computed tomograms were taken immediately before and after surgery, at the uncovering of the implant, and after a 6 month healing period. A bone biopsy was taken on the previous bony window area to evaluate new bone formation. Results:A total of 21 implants in lengths of 10 to 15 mm (mean, 13 mm) were placed, with an average residual bone height of 5 mm (range, 1–9 mm). All implants remained stable during the study period in clinical evaluations. New bone formation and new sinus floors were found in radiographic and histologic evaluations. Conclusions:The human study showed the capacity of new bone formation in the maxillary sinus with membrane elevation only and simultaneous implant placement beyond the original sinus floor. New bone formation without additional bone graft in the maxillary sinus is revealed from the clinical, radiographic, and histologic results, but furthermore long-term studies are needed to confirm this.

New Bone Formation in the Maxillary Sinus Using Peripheral Venous Blood Alone

PURPOSE The purpose of this study was to evaluate the amount of bone formation under a sinus membrane tented with implants and filled with venous blood as a graft material. MATERIALS AND METHODS Fourteen patients (17 sinus augmentations) were consecutively treated with sinus floor elevation via the lateral window approach. The lateral bony window was created using a piezoelectric saw, and the sinus membrane was elevated to make a new compartment. After resorbable blast media-surfaced dental implants were placed simultaneously, the collected peripheral venous blood was applied to support the sinus membrane over the implant apex, and the bony portion of the lateral window was repositioned to seal the lateral window. In 6 cases, samples were taken for biopsy at the time of second stage surgery. RESULTS An average of 6.8 months after the sinus augmentation, new bone consolidation in the maxillary sinus was observed by radiographic and histologic evaluation. Vital bone formation was 38.70% according to the histomorphometric data. Of the 31 implants placed, 2 failed. The overall implant survival rate was 93.5%. All failures occurred when implants were placed into the extraction socket and were associated with poor initial stability. CONCLUSION This study suggests that simultaneous placement of dental implants and injection of peripheral venous blood as a graft material appears to be a safe alternative procedure for maxillary sinus augmentation.

Zinc-deficient diet decreases fetal long bone growth through decreased bone matrix formation in mice.

This study evaluated the effects of zinc on skeletal development during fetal development in pregnant ICR mice fed a zinc-deficient (3 mg/kg) or zinc-adequate (30 mg/kg) diet. We also included a group pair-fed with the zinc-deficient group to control for decreased appetite due to zinc deficiency. Developing fetuses at embryonic day 18.5 were removed by cesarean section, and the skeletal development was evaluated by histological analysis as well as by body weight and longitudinal growth measurement. Reduced maternal food intake in the zinc-deficient and pair-fed groups resulted in a marked and significant (P < .05) decrease in fetal weight compared to that of the zinc-adequate group. However, fetal length retardation in the pair-fed group was less marked than in the zinc-deficient group, suggesting that reduced supply of zinc from maternal circulation may play a role in longitudinal growth through skeletal development. The fetal developing tibia of the zinc-deficient group showed marked shortening of diaphysis and a mild narrowing of the hypertrophic chondrocyte zone width with increased osteoclast number, but there was no influence on the mineralization of bone matrix. This may be the result of reduced activation of osteoblasts and maturation of chondrocytes with increased osteoclastic activity, suggesting that zinc deficiency during the fetal development has a greater impact on the matrix formation of bone than the mineralization of bone matrix.

A method of sealing perforated sinus membrane and histologic finding of bone substitutes: a case report.

To augment the atrophic posterior maxilla, a sinus bone graft has been widely used for sinus floor augmentation. Various bone substitutes have been developed and grafted in the maxillary sinus with and without membranes perforation, although autogenous bone is recommended as a gold standard of grafting materials. Membrane perforation is the most common complication associated with sinus bone graft. To repair a perforation, various methods have been developed. This case report is focused on histologic findings of 1 bovine hydroxyapatite (Bio-Oss®; Geistlich Pharma AG, Wolhusen, Switzerland) and 2 kinds of human mineral allograft- Tutoplast® cancellous microchips (TutoGen Medical GmbH, Neunkirchen am. Brand Germany), and irradiated allogeniccancellous bone and marrow (ICB®; Rocky Mountain Tissue Bank, Aurora, CO) used for sinus graft in the same patient with membrane perforation after various healing periods. Mineral allograft showed favorable new bone regeneration with the repair of membrane perforation. This case report also describes a technique regarding how to repair completely perforated sinus membrane after the removal of a mucocele using human collagen membrane (Tutoplast® pericardium; TutoGen Medical GmbH) and fibrin adhesive (Greenplast®; Green Cross Co., Youngin, Korea) to stabilize collagen membrane.

Fungal infection as a complication of sinus bone grafting and implants: a case report

Sinus bone grafts have been used successfully to augment atrophic posterior maxilla for dental implant placement. Even though sinus bone grafting is generally considered to be a safe surgical procedure, postoperative maxillary sinus infections can occur and therefore need to be considered. Bacteria, as well as viruses and fungi, have been identified as causative agents. Because fungal infection of the maxillary sinus after sinus bone grafting is not well known, we report a case of a middle-aged male patient along with the clinical, radiographic, and histologic findings. The patient was referred from his private dentist because of failed sinus bone grafting and osseointegration of implants. The surgical approach to the sinus yielded a friable mass of brownish-red material from the sinus. Review of pathology slides revealed a noninvasive hyphal mass caused by Aspergillus and polypous mucosa. After surgical removal of the mycotic masses, sinus bone grafting, using allograft, was performed. Bone formation after the healing period was favorable and dental implants were placed. There was no recurrence of fungal sinusitis.

Serotoninergic modulation of GABAergic synaptic transmission in developing rat CA3 pyramidal neurons

Serotoninergic modulation of GABAergic mIPSCs was investigated in immature (postnatal 12–16‐days old) rat CA3 pyramidal neurons using a conventional whole‐cell patch clamp technique. Serotonin or 5‐hydroxytryptamine (5‐HT) (10 μmol/L) transiently and explosively increased mIPSC frequency with a small increase in the current amplitude. However, 5‐HT did not affect the GABA‐induced postsynaptic currents, indicating that 5‐HT acts presynaptically to facilitate the probability of spontaneous GABA release. The 5‐HT action on GABAergic mIPSC frequency was completely blocked by 100 nmol/L MDL72222, a selective 5‐HT3 receptor antagonist, and mimicked by mCPBG, a selective 5‐HT3 receptor agonist. The 5‐HT action on GABAergic mIPSC frequency was completely occluded either in the presence of 200 μmol/L Cd2+ or in the Na+‐free external solution, suggesting that the 5‐HT3 receptor‐mediated facilitation of mIPSC frequency requires a Ca2+influx passing through voltage‐dependent Ca2+channels from the extracellular space, and that presynaptic 5‐HT3 receptors are less permeable to Ca2+. The 5‐HT action on mIPSC frequency in the absence or presence of extracellular Na+ gradually increased with postnatal development. Such a developmental change in the 5‐HT3 receptor‐mediated facilitation of GABAergic transmission would play important roles in the regulation of excitability as well as development in CA3 pyramidal neurons.

Histomorphometric evaluation of mineralized cancellous allograft in the maxillary sinus augmentation: a 4 case report.

Purpose:The aim of this article is to report the histomorphometric analysis and clinical study of mineralized cancellous bone allografts in maxillary sinus augmentation procedures in 4 cases. Materials and Methods:Sinus bone augmentation, using a piezoelectric device and mineralized cancellous allografts, was performed in 3 patients. After an average of about 8 months of healing, a trephine core sample was gained from the lateral windows area for histomorphometric analysis. The mineralized cancellous allografts demonstrated normal healing of hard tissues. Results:Upon reentry for dental implant placement or secondary surgery, the graft materials showed hard bony structures within the maxillary sinus. Histomorphometric analysis of the cores revealed an average vital new bone content of 17.88%. Conclusion:Mineralized cancellous allografts showed favorable bone regeneration histologically and was clinically useful in augmenting bone volume for implant placement in the sinus bone graft.