Effects of 4-hexylresorcinol on facial skeletal development in growing rats: Considerations for diabetes.

Objective: : To investigate the long-term effects of 4-hexylresorcinol (4HR) on facial skeletal growth in growing male rats, with a focus on diabetic animal models. Methods: : Forty male rats were used. Of them, type 1 diabetes mellitus was induced in 20 animals by administering 40 mg/kg streptozotocin (STZ), and they were assigned to either the STZ or 4HR-injected group (STZ/4HR group). The remaining 20 healthy rats were divided into control and 4HR groups. We administered 4HR subcutaneously at a weekly dose of 10 mg/kg until the rats were euthanized. At 16 weeks of age, whole blood was collected, and micro-computed tomography of the skull and femur was performed. Results: : All craniofacial linear measurements were smaller in the STZ group than in the control group. The mandibular molar width was significantly smaller in the 4HR group than in the control group (P = 0.031) but larger in the STZ/4HR group than in the STZ group (P = 0.011). Among the diabetic animals, the STZ/4HR group exhibited significantly greater cortical bone thickness, bone mineral density, and bone volume than the STZ group. Serum testosterone levels were also significantly higher in the STZ/4HR group than in the STZ group. Conclusions: : 4HR administration may have divergent effects on mandibular growth and bone mass in healthy and diabetic rats. In the context of diabetes, 4HR appears to have beneficial effects, potentially through the modulation of mitochondrial respiration.

Relevant Properties and Potential Applications of Sericin in Bone Regeneration.

The potential of sericin, a protein derived from silkworms, is explored in bone graft applications. Sericin's biocompatibility, hydrophilic nature, and cost-effectiveness make it a promising candidate for enhancing traditional graft materials. Its antioxidant, anti-inflammatory, and UV-resistant properties contribute to a healthier bone-healing environment, and its incorporation into 3D-printed grafts could lead to personalized medical solutions. However, despite these promising attributes, there are still gaps in our understanding. The precise mechanism through which sericin influences bone cell growth and healing is not fully understood, and more comprehensive clinical trials are needed to confirm its long-term biocompatibility in humans. Furthermore, the best methods for incorporating sericin into existing graft materials are still under investigation, and potential allergic reactions or immune responses to sericin need further study.

Denosumab-associated jaw bone necrosis in cancer patients: retrospective descriptive case series study.

BACKGROUND: Denosumab (DMB) is a bone antiresorptive agent used to treat osteoporosis or metastatic cancer of the bones. However, denosumab-associated osteonecrosis of the jaw (DRONJ) has become a common complication in cancer patients. The prevalence of osteonecrosis of the jaw (ONJ) in cancer patients is estimated to be similar for both bisphosphonate-related cases (1.1 to 1.4%) and denosumab-related cases (0.8 to 2%), with the addition of adjunctive therapy with anti-angiogenic agents reportedly increasing its prevalence to 3%. (Spec Care Dentist 36(4):231-236, 2016). The aim of this study is to report on DRONJ in cancer patients treated with DMB (Xgeva®, 120mg). CASE PRESENTATION: In this study, we identified four cases of ONJ among 74 patients receiving DMB therapy for metastatic cancer. Of the four patients, three had prostate cancer and one had breast cancer. Preceding tooth extraction within 2 months of the last DMB injection was found to be a risk factor for DRONJ. Pathological examination revealed that three patients had acute and chronic inflammation, including actinomycosis colonies. Among the four patients with DRONJ referred to us, three were successfully treated without complications and had no recurrence following surgical treatment, while one did not follow up. After healing, one patient experienced a recurrence at a different site. Sequestrectomy in conjunction with antibiotic therapy and cessation of DMB use proved to be effective in managing the condition, and the ONJ site healed after an average 5-month follow-up period. CONCLUSION: Conservative surgery, along with antibiotic therapy and discontinuation of DMB, was found to be effective in managing the condition. Additional studies are needed to investigate the contribution of steroids and anticancer drugs to jaw bone necrosis, the prevalence of multicenter cases, and whether there is any drug interaction with DMB.

The Effect of Buccal Fat Pad Graft in the Palatoplasty and the Risk Factor of Postoperative Palatal Fistula.

PURPOSE: The aim of this study was to evaluate the effect of buccal fat pad (BFP) in the palatoplasty and to investigate the risk factors associated with postoperative palatal fistula formation. MATERIALS AND METHODS: Sixty-five cleft palate patients were enrolled for this study. Clinical data regarding sex, age, type of cleft, surgical technique, the ratio of cleft width, and BFP graft were collected. The ratio of cleft width was measured and calculated using preoperative clinical photographs. In 36 patients, the BFP was harvested and grafted on the cleft palate to prevent palatal fistula formation. The patients were followed up, the incidence of fistula formation was investigated, and the risk factors related with the fistula were evaluated. RESULTS: Four patients had postoperative palatal fistula and were not BFP grafted during operation. The BFP graft and ratio of cleft width are significant factors in palatal fistula formation (P = .035, .003). There was a significant difference in the ratio of cleft width between the normal and fistula groups (P = .006). In the logistic regression analysis, there was significant association between high ratio of cleft width and palatal fistula formation in the no BFP group (odds ratio; 11.15, P = .036). CONCLUSIONS: The ratio of cleft width and BFP graft was a significant factor in palatal fistula formation. The BFP graft is a reliable procedure to prevent palatal fistula formation and increase the success of palatoplasty.

Retrospective comparative clinical study for silk mat application into extraction socket.

BACKGROUND: Silk mats have been approved for clinical trials by the Korean Food and Drug Administration as membranes for guided tissue regeneration (GTR). In this study, silk mat application was compared to high-density polytetrafluoroethylene (dPTFE) membrane application or no membrane group. METHODS: To compare the silk mat group to the dPTFE group or the no membrane group, a retrospective sample collection was conducted. Bony defects were measured at the time of extraction (T0) and then at 3 months (T1) and 6 months after extraction (T2) on a digital panoramic view. Bone gain (BG) was calculated by subtracting from the bony defect at T0 to the bony defect at each follow-up. RESULTS: The BG at T2 was 2.44 ± 2.49 mm, 4.18 ± 1.80 mm, and 4.24 ± 2.05 mm in the no membrane group, silk mat group, and dPTFE group, respectively. Both membrane groups had significantly higher BG than BG in the no membrane group at T2 (P < 0.05). CONCLUSIONS: Both membrane groups showed higher BG than the no membrane group.

Accelerated biodegradation of silk sutures through matrix metalloproteinase activation by incorporating 4-hexylresorcinol.

Silk suture material is primarily composed of silk fibroin and regarded as a non-resorbable material. It is slowly degraded by proteolysis when it is implanted into the body. 4-Hexylresorcinol (4HR) is a well-known antiseptic. In this study, the biodegradability of 4HR-incorporated silk sutures were compared to that of untreated silk sutures and polyglactin 910 sutures, a commercially available resorbable suture. 4HR-incorporated silk sutures exhibited anti-microbial properties. Matrix metalloproteinase (MMP) can digest a wide spectrum of proteins. 4HR increased MMP-2, -3, and -9 expression in RAW264.7 cells. MMP-2, -3, and -9 were able to digest not only silk fibroin but also silk sutures. Consequently, 59.5% of the 4HR-incorporated silk suture material remained at 11 weeks after grafting, which was similar to that of polyglactin 910 degradation (56.4% remained). The residual amount of bare silk suture material at 11 weeks after grafting was 91.5%. The expression levels of MMP-2, -3 and -9 were high in the 4HR-incorporated silk suture-implanted site 12 weeks after implantation. In conclusion, 4HR-treated silk sutures exhibited anti-microbial properties and a similar level of bio-degradation to polyglactin 910 sutures and induced higher expression of MMP-2, -3, and -9 in macrophages.

A New Method of Fixation With the Yang's Keyhole Plate System for the Treatment of Mandible Fractures.

PURPOSE: This study was designed to assess the clinical outcomes and surgical convenience of a newly designed Yang's Keyhole plate (YK plate) system for treatment of subcondyle and angle fractures of the mandible. To evaluate the system's clinical outcomes and surgical convenience, chart review and surgical simulation using a mandible replica model were performed. METHODS: The YK plate system, which is a slightly modified sliding plate, has 0.8-mm thick titanium and a widened hole in the anterior region to permit a screw head to be inserted. The clinical results and clinical convenience of the newly developed YK plate system and the existing 4-hole miniplate fixation technique were compared using a surgical simulation. Moreover, the clinical results of the patients who underwent mandibular surgery were compared during the follow-up examination periods (ie, weeks 1, 2, 4, 8, and 16). RESULTS: No critical complications in any of the 22 patients were reported during the 4-month follow-up period. The results of the assessment of clinical convenience using the surgical simulation showed that using the YK plate system was more convenient and saved time compared to using the 4-hole miniplate. CONCLUSION: The newly developed YK plate system can be applied to subcondyle and angle fractures of the mandible and can provide reliable and convenient application and use.

Surgically assisted rapid palatal expansion with tent screws and a custom-made palatal expander: a case report.

Rapid palatal expansion(RPE) with the tooth-born appliance is not sufficient to apply to the patients with periodontal problem or insufficient tooth anchorage, and it leads to tipping of the anchorage teeth and increasing teeth mobility and root resorption. To avoid these disadvantages, we present the case using palatal screws and custommade palatal expander. A 23-year-old patient underwent surgically assisted rapid maxillary expansion with the Hyrax expansion using 4 tent screws. The study models were used to measure the pre-/-post surgical width of the anterior and posterior dental arches with a digital sliding caliper. In the result, the custom-made palatal expander with 4 tent screws is suitable for delivering a force to the mid-palatal suture expansion. And it is low cost, small sized and simply applied. The results indicated that maxillary expansion with the custom-made palatal anchorage device is predictable and stable technique without significant complications in patients.

Comparable efficacy of silk fibroin with the collagen membranes for guided bone regeneration in rat calvarial defects.

PURPOSE: Silk fibroin (SF) is a new degradable barrier membrane for guided bone regeneration (GBR) that can reduce the risk of pathogen transmission and the high costs associated with the use of collagen membranes. This study compared the efficacy of SF membranes on GBR with collagen membranes (Bio-Gide®) using a rat calvarial defect model. MATERIALS AND METHODS: Thirty-six male Sprague Dawley rats with two 5 mm-sized circular defects in the calvarial bone were prepared (n=72). The study groups were divided into a control group (no membrane) and two experimental groups (SF membrane and Bio-Gide®). Each group of 24 samples was subdivided at 2, 4, and 8 weeks after implantation. New bone formation was evaluated using microcomputerized tomography and histological examination. RESULTS: Bone regeneration was observed in the SF and Bio-Gide®-treated groups to a greater extent than in the control group (mean volume of new bone was 5.49 ± 1.48 mm(3) at 8 weeks). There were different patterns of bone regeneration between the SF membrane and the Bio-Gide® samples. However, the absolute volume of new bone in the SF membrane-treated group was not significantly different from that in the collagen membrane-treated group at 8 weeks (8.75 ± 0.80 vs. 8.47 ± 0.75 mm(3), respectively, P=.592). CONCLUSION: SF membranes successfully enhanced comparable volumes of bone regeneration in calvarial bone defects compared with collagen membranes. Considering the lower cost and lesser risk of infectious transmission from animal tissue, SF membranes are a viable alternative to collagen membranes for GBR.

Condylar repositioning in bilateral sagittal split ramus osteotomy with centric relation bite.

PURPOSE: Changes in the condylar position after bilateral sagittal split ramus osteotomy (BSSO) can cause many complications, such as condylar dysfunction and increased risk of relapse. This study evaluated a simple approach for condylar repositioning in BSSO as a method to rapidly obtain the patient's centric relation (CR) bite position without prefabricated equipment. METHODS: The study subjects included 9 patients (5 men and 4 women; mean age, 23.7 years) who underwent BSSO in the Department of Oral and Maxillofacial Surgery in Hallym University hospital between December 2009 and March 2012. We performed BSSO with the condylar-repositioning method according to the patient's CR bite. RESULTS: Measurements of changes in the condylar position via radiographic images (lateral cephalometric radiographs) did not indicate significant differences after surgery (P < 0.05). In surveys of temporomandibular joint symptoms, the scores for categories (sound, pain, mouth opening limitation) also did not show any increases after surgery. CONCLUSIONS: Within a standard operating time, the condyle was effectively repositioned using the condylar-repositioning method described in this study. These results indicate this new repositioning method is simple and eliminates the need for any additional device.

Design and application of hybrid maxillomandibular fixation for facial bone fractures.

PURPOSE: A novel maxillomandibular fixation (MMF) procedure using a skeletal anchorage screw (SAS) (in the maxilla) and an arch bar (in the mandible), which we call "hybrid maxillomandibular fixation," was explored in this study. The aims of the study were to examine the efficacy of our hybrid MMF method and to compare periodontal tissue health and occlusal rehabilitation among 3 MMF methods. MATERIALS AND METHODS: In total, 112 patients who had undergone open reduction at the Department of Oral and Maxillofacial Surgery between September 2005 and December 2012 were selected for this study. The participants were assigned to one of the following groups: SAS (maxilla), SAS (mandible), SAS-arch bar, or arch bar-arch bar. Periodontal health was evaluated using the Gingival Index, and the perioperative occlusal reproducibility was evaluated using a score of 1 to 3. Statistical analysis was performed using parametric tests (Student t test or 1-way analysis of variance followed by post hoc Tukey test). RESULTS: In the Gingival Index comparison performed 1 month after the surgery, only the group using the arch bars and wiring was significantly different from the other groups (P < 0.05). The occlusal reproducibility scores were not significantly different. The pain and discomfort of the patients were reduced in the hybrid MMF group. CONCLUSIONS: The hybrid MMF takes advantage of MMF using both arch bars and SASs for mandibular fractures. In addition, it overcomes many problems presented by previous MMF methods.

Condylar repositioning using centric relation bite in bimaxillary surgery.

OBJECTIVE: The purpose of this study was to evaluate displacement of the mandibular condyle after orthognathic surgery using a condylar-repositioning device. METHODS: The patient group comprised 20 adults who underwent bimaxillary surgery between August 2008 and July 2011. The degree of condylar displacement was measured by pre- and postoperative tomographic analysis using centric relation bite and a wire during surgery. A survey assessing temporomandibular joint (TMJ) sound, pain, and locking was performed. The 20 tomographs and surveys were analyzed using the Wilcoxon signed-rank test and McNemar's test, respectively. RESULTS: No significant changes were observed in the anterior, superior, or posterior joint space of the TMJ (p > 0.05). In addition, no significant change was observed in TMJ sound (p > 0.05). However, TMJ pain and locking both decreased significantly after surgery (p < 0.05). CONCLUSIONS: Due to its simplicity, this method may be feasible and useful for repositioning condyles.

Cisplatin and 4-hexylresorcinol synergise to decrease metastasis and increase survival rate in an oral mucosal melanoma xenograft model: a preliminary study.

The present study was undertaken to examine the effects of cisplatin plus 4-hexylresorcinol (4-HR) combination therapy on oral mucosal melanoma (OMM) using cultured primary OMM cells in a tumour xenograft model. Cultured primary OMM cells were used for the MTT assay and DNA microarray. OMM cells were implanted into the submandibular glands of nude mice. The mice were then treated with cisplatin only or cisplatin plus 4-HR. Tumour size changes, survival rate and tumour metastasis were compared between the two groups by observation, micro-positron emission tomography (PET) and histological examination. In the MTT assay, the cisplatin plus 4-HR group showed significantly higher inhibition of OMM cell growth compared to the other groups (p<0.05). DNA microarray results showed significant inhibition of matrix metalloproteinase (MMP)-2 gene expression upon 4-HR application. The necropsy and micro-PET results showed that the mice from the cisplatin-only group had more distant metastases than the mice from the cisplatin plus 4-HR combination group (p=0.002). MMP-2 expression was lower in the primary tumours in the cisplatin plus 4-HR combination group than in the cisplatin-only group (p<0.001). Overall survival was longer in mice from the cisplatin plus 4-HR combination group than in the cisplatin-only group (p=0.049). In conclusion, the combined effect of cisplatin and 4-HR resulted in fewer metastases and longer survival than cisplatin-only treatment in the OMM xenograft model.

Restoration of a peri-implant defect by platelet-rich fibrin.

OBJECTIVE: The objective of this study was to evaluate the application of platelet-rich fibrin (PRF) into a peri-implant defect in vivo. STUDY DESIGN: Eight New Zealand white rabbits were used for this study. Two peri-implants with defects sized 3.0 × 5.0 mm (width × length) were prepared after drilling to host the dental implant in the tibia. Subsequently, the 2 dental implants were installed (diameter, 3.0 mm and length, 8.0 mm). In the experimental group, PRF was applied into the bony defect. In the control group, the peri-implant defect was left unfilled. The animals were humanely killed 8 weeks after implantation and histomorphometric analysis was done. RESULTS: In the histomorphometric analysis, mean new bone formation was 29.30% ± 7.50% in the experimental group and 11.06% ± 8.94% in the control group (P = .020). Mean bone-to-implant contact was 39.43% ± 7.39% in the experimental group and 17.11% ± 8.12% in the control group (P = .006). CONCLUSIONS: In the animal model, peri-implant defect sized 3.0 × 5.0 mm (width × length) was successfully repaired by the application of PRF alone.

Accelerated healing with the use of a silk fibroin membrane for the guided bone regeneration technique.

OBJECTIVE: The purpose of this study was to evaluate the bone regeneration ability of silk fibroin (SF) membrane. STUDY DESIGN: Fourier-transform infrared (FT-IR) and solubility test against distilled water were performed with 3 different types of SF membrane (SM1, SM2, and SM3). Subsequently, microscopic computerized tomography (µ-CT) and histomorphometric analyses were performed in rabbit calvarial defect model after SF membrane application at 4 and 8 weeks after surgery. RESULTS: FT-IR showed that the conformation of the SF membrane was a random coil structure and that SM1 was the least soluble. When SM1 was used in the animal model, the groups with SM1 had significantly higher new bone formation than the uncovered control in both the µ-CT and the histomorphometric analyses (P < .05). CONCLUSIONS: The SF membrane had more new bone formation compared with the uncovered control.

Development of nano-hydroxyapatite graft with silk fibroin scaffold as a new bone substitute.

PURPOSE: This study involves a comparison between the bone regeneration of nano-hydroxyapatite (nHA), as derived from eggshells either with or without silk fibroin scaffolds, and the unfilled control in the rabbit calvarial bony defect model. MATERIALS AND METHODS: Sixteen 4-month-old New Zealand white rabbits, with a mean weight of 2.8 kg (range, 2.5-3.0 kg), were used in this experiment. After the formation of bilateral parietal bony defects (diameter, 8.0 mm), either an nHA or an nHA+silk fibroin combination (nHA+silk) was grafted. The control was unfilled defect. The bone regeneration was evaluated by micro-computed tomography (µCT) and histomorphometric analyses at 4 and 8 weeks. RESULTS: All measured variables of the µCT analysis were significantly higher in the grafted groups (nHA and nHA+silk) than in the unfilled control groups at both 4 and 8 weeks after operation (P < .05). On histomorphometric analysis, there was no significant difference between the groups at 4 weeks after operation. However, the nHA group exerted significantly higher bone regeneration (40.16% ± 8.27%) compared with the unfilled control group (25.66% ± 10.98%) or the nHA+silk group (16.62% ± 3.05%) (P < .05). CONCLUSION: The nHA from eggshells exerted better bone formation than the unfilled control group on both µCT and histomorphometric analyses. Considering the rapid healing in bony defect and easy availability, the nHA from the eggshells could prove to be a good new bone substitute.

Effects of installation depth on survival of an hydroxyapatite-coated Bicon implant for single-tooth restoration.

PURPOSE: The present retrospective study evaluated various implant surface factors associated with Bicon implant survival for single-tooth restoration in the healthy individual. PATIENTS AND METHODS: A retrospective cohort study design was used. A total of 613 Bicon (Bicon System, Boston, MA) implants (272 patients) were included. Because the use of hydroxyapatite (HA) coating has been controversial, the surface type was chosen according to the patient's preference. A total of 308 HA-coated implants and 305 titanium plasma-sprayed (TPS) implants were used. The macroanatomy of both implant types was identical. Patients who had systemic disease, poor quality bone, or removable prosthetics were excluded from the present study. A chart review was conducted to record age, gender, implant diameter, implant length, installation depth, installation location, and the use of bone grafting. Implant failure was recorded, and the data were analyzed using the chi(2) test and logistic regression analysis. RESULTS: The installation depth was an important prognostic factor in the HA-coated implants. The failure rate for the HA-coated implants installed at margin level and 2 mm below level was 10.29% and 3.01%, respectively (chi(2) = 6.035, P = .014). The implant length was an important prognostic factor for the TPS-treated implants. The failure rate recorded for the TPS-treated implants installed with a length of less than 10 mm and 10 mm or longer was 15.46% and 2.40%, respectively (chi(2) = 18.414, P < .001). CONCLUSION: Many factors can influence the failure rate of TPS and HA-coated Bicon implants. Among these, installation depth played an especially significant role in the success of HA-coated Bicon implants in the present study.

Low molecular weight silk fibroin increases alkaline phosphatase and type I collagen expression in MG63 cells.

Silk fibroin, produced by the silkworm Bombyx mori, has been widely studied as a scaffold in tissue engineering. Although it has been shown to be slowly biodegradable, cellular responses to degraded silk fibroin fragments are largely unknown. In this study, silk fibroin was added to MG-63 cell cultures, and changes in gene expression in the MG-63 cells were screened by DNA microarray analysis. Genes showing a significant (2-fold) change were selected and their expression changes confirmed by quantitative RT-PCR and western blotting. DNA microarray results showed that alkaline phosphatase (ALP), collagen type-I alpha-1, fibronectin, and transforming growth factor-beta1 expressions significantly increased. The effect of degraded silk fibroin on osteoblastogenic gene expression was confirmed by observing up-regulation of ALP activity in MG-63 cells. The finding that small fragments of silk fibroin are able to increase the expression of osteoblastogenic genes suggests that controlled degradation of silk fibroin might accelerate new bone formation. [BMB reports 2010; 43(1): 52-56].

A combination graft of low-molecular-weight silk fibroin with Choukroun platelet-rich fibrin for rabbit calvarial defect.

OBJECTIVE: The objective of this study was to determine the capabilities of silk fibroin as a biomaterial template for bone formation when mixed with Choukroun platelet-rich fibrin (PRF) in vivo. STUDY DESIGN: Ten New Zealand white rabbits were used for this study and bilateral round shaped defects were formed in the parietal bone (diameter 9.0 mm). The silk fibroin was digested by acid and made into powder (molecular weight <1.0 kDa). The right side (experimental group) received the silk fibroin plus platelet-rich fibroin and the left side (control group) did not receive a graft. Animals were killed at 6 weeks and 12 weeks. The specimens were examined by microscopic computerized tomography (micro-CT). Subsequently, they underwent decalcification and were stained for histologic analysis. RESULTS: There was no significant difference between groups at 6 weeks after operation. In the micro-CT results, however, tissue mineral content in the experimental group at 12 weeks after operation was 132.09 +/- 4.41 and that in the control group was 126.42 +/- 6.62 (P = .011). Tissue mineral density in the experimental group was 2,088.88 +/- 648.34, and that in the control group was 2,029.72 +/- 668.22 (P = .013). The results of the histomorphometric analysis were in accordance with the micro-CT results. The total new bone was 49.86 +/- 7.49% in the control group at 12 weeks after the operation and 59.83 +/- 10.92% in the experimental group (P = .021). CONCLUSION: A combined application of Choukroun PRF with acid-digested silk fibroin showed more rapid bone healing than unfilled control.