Secondary Malignancies in Multiple Myeloma in Korean Patients: A Nationwide Population-Based Study.

Purpose: This study investigated the incidence of secondary malignancy in multiple myeloma (MM) patients compared with that in the general population using a population-based database covering all residents in Korea. Materials and Methods: Based on the national health insurance system in Korea, all people primarily diagnosed with MM between January 1, 2010 to December 31, 2018 were identified. A total of 9,985 MM patients aged ≥20 years in Korea were included. Results: Among them, 237 (2.4%) developed secondary malignancies by 2018. The standardized incidence rates (SIRs) of all secondary malignancies in MM patients were 0.87 (95% confidence interval [CI]=0.76-0.98), with a higher incidence of hematologic malignancies than in the general population with an SIR of 3.80 (95% CI=2.61-5.00). The incidence rates of both lymphoid malignancy (SIR=3.56; 95% CI=2.31-4.82) and myeloid malignancy (SIR=3.78; 95% CI=1.16-6.39) were higher in MM patients than in the general population. In contrast, a lower incidence of solid cancer was observed in MM patients than in the general population (SIR=0.76, 95% CI=0.65-0.86). There was no significant difference in survival in MM patients without secondary malignancies, with hematologic malignancy, and with solid cancer (p-value=0.413). Conclusion: MM patients had a greater risk of secondary malignancies, especially hematologic malignancies, than the general population. Future studies with a focus on analyzing patients' history, treatment details, and genetic information in various stages of MM patients are needed to better understand the mechanism behind this increased risk.

Free Volume Effect via Various Chemical Structured Monomers on Adhesion Property and Relative Permittivity in Acrylic Pressure Sensitive Adhesives.

Acrylic pressure-sensitive adhesives (PSAs) are used as fixatives between layers of a display. PSAs' function is an important factor that determines the performance of the display. Of the various display types available, the touch screen panel (TSP) of smart devices is firmly related to the relative permittivity of the elementals. Therefore, adjusting the relative permittivity of the PSA is indispensable for driving the TSP. Accordingly, selected acrylic pre-polymers were polymerized and the pre-polymer was blended and cross-linked with monomers with different chemical structure to adjust the relative permittivity. The monomers were hexametyldisiloxane (HMDS), N-vinylcaprolactam (NVC), tert-butyl acrylate (TBA), and isooctadecyl acrylate (ISTA). The gel fraction and transmittance as a function of the monomers show a similar result to the pure acrylic PSA. However, the gel fraction value decreased to about 90% and the transmittance decreased to about 85%, due to the immiscibility between nonpolar HMDS and acrylic PSA. On the other hand, the adhesion properties were improved when NVC was added because of the polarity of the nitrogen group. In addition, the relative permittivity of the PSA decreased regardless of the monomer chosen. There was, however, a difference in the optimal content of each monomer, and NVC decreased from 4 phr content to about 3.4 in reducing relative permittivity. Through the above results, it was confirmed that NVC having a nitrogen group is most advantageous in lowering adhesion properties and relative permittivity, and necessitates further research based on the findings.

Assessment of the proximity between the mandibular third molar and inferior alveolar canal using preoperative 3D-CT to prevent inferior alveolar nerve damage.

BACKGROUND: The inferior alveolar nerve (IAN) may be injured during extraction of the mandibular third molar, causing severe postoperative complications. Many methods have been described for evaluating the relative position between the mandibular third molar and the inferior alveolar canal (IAC) on panoramic radiography and computed tomography, but conventional radiography provides limited information on the proximity of these two structures. The present study assessed the benefits of three-dimensional computed tomography (3D-CT) prior to surgical extraction of the mandibular third molar, to prevent IAN damage. METHODS: This retrospective study included 4917 extractions in 3555 patients who presented for extraction of the mandibular third molars. The cases were classified into three groups, according to anatomical relationship between the mandibular third molars and the IAC on panoramic radiography and whether 3D-CT was performed. Symptoms of IAN damage were assessed using the touch-recognition test. Data were compared using the chi-square test and Fisher's exact test. RESULTS: Among the 32 cases of IAN damage, 6 cases were included in group I (0.35 %, n = 1735 cases), 23 cases in group II (1.1 %, n = 2063 cases), and 3 cases in group III (0.27 %, n = 1119 cases). The chi-square test showed a significant difference in the incidence of IAN damage between groups I and II. No significant difference was observed between groups I and III using Fisher's exact test. In the 6 cases of IAN damage in group I, the mandibular third molar roots were located lingual relative to the IAC in 3 cases and middle relative to the IAC in 3 cases. The overlap was ≥2 mm in 3 of 6 cases and 0-2 mm in the remaining 3 cases. The mean distance between the mandibular third molar and IAC was 2.2 mm, the maximum distance 12 mm, and the minimum distance 0.5 mm. Greater than 80 % recovery was observed in 15 of 32 (46.8 %) cases of IAN damage. CONCLUSIONS: 3D-CT may be a useful tool for assessing the three-dimensional anatomical relationship and proximity between the mandibular third molar and IAC in order to prevent IAN damage during extraction of mandibular third molars.

New bone formation between bare titanium surface and hydroxyapatite coating by the aerosol deposition technique in the nasal mucosal penetration model.

OBJECTIVE: The aim of this study was to compare new bone formation with titanium (Ti) surface and hydroxyapatite (HA)-coated titanium surface in mucosal perforation model. MATERIALS AND METHODS: HA coating to the Ti disc and implant were done by aerosol deposition technique. Alkaline phosphatase assay and cell migration assay were done in Ti and HA surface disc with MG63 cells. For the in vivo test, 5 New Zealand white rabbits were used. Two penetration defects were prepared in the nasal bone. Subsequently, 2 types of implants were installed into the defect (diameter: 3.0 mm, length: 6.0 mm). Approximately 5.0 mm of the fixture's surface penetrated into the nasal cavity. In the experimental group, HA-coated implants were used. The same design of implants without coating was used in the control group. The animals were sacrificed 8 weeks postoperatively. Subsequently, a histomorphometric analysis was done. RESULTS: Alkaline phosphatase activity was significantly higher in HA-coated surface than in titanium surface (P < 0.05). In addition, more cells were migrated into the HA-coated surface when compared to Ti surface. In the animal experiments, mean new bone formation was 30.68 ± 14.16% in the experimental group and 6.92 ± 5.12% in the control group (P = 0.001). Mean bone-to-implant contact was 31.71 ± 8.41% in the experimental group and 7.98 ± 5.58% in the control group (P < 0.001). Mean height of the bone regeneration was 3.70 ± 0.76 mm in the experimental group and 1.04 ± 0.67 mm in the control group. The difference between the 2 groups was statistically significant (P < 0.001). CONCLUSIONS: HA-coated implants exhibited more bone regeneration in the mucosal penetration model than the uncoated implants.

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.