Two-year survival analysis of twisted wire fixed retainer versus spiral wire and fiber-reinforced composite retainers: a preliminary explorative single-blind randomized clinical trial / 대한치과교정학회지

OBJECTIVE: Traditional retainers (both metal and fiber-reinforced composite [FRC]) have limitations, and a retainer made from more flexible ligature wires might be advantageous. We aimed to compare an experimental design with two traditional retainers. METHODS: In this prospective preliminary clinical trial, 150 post-treatment patients were enrolled and randomly divided into three groups of 50 patients each to receive mandibular canine-to-canine retainers made of FRC, flexible spiral wire (FSW), and twisted wire (TW). The patients were monitored monthly. The time at which the first signs of breakage/debonding were detected was recorded. The success rates of the retainers were compared using chi-squared, Kaplan-Meier, and Cox proportional-hazard regression analyses (α = 0.05). RESULTS: In total, 42 patients in the FRC group, 41 in the FSW group, and 45 in the TW group completed the study. The 2-year failure rates were 35.7% in the FRC group, 26.8% in the FSW group, and 17.8% in the TW group. These rates differed insignificantly (chi-squared p = 0.167). According to the Kaplan-Meier analysis, failure occurred at 19.95 months in the FRC group, 21.37 months in the FSW group, and 22.36 months in the TW group. The differences between the survival rates in the three groups were not significant (Cox regression p = 0.146). CONCLUSIONS: Although the failure rate of the experimental retainer was two times lower than that of the FRC retainer, the difference was not statistically significant. The experimental TW retainer was successful, and larger studies are warranted to verify these results.

Variations in surface roughness of seven orthodontic archwires: an SEM-profilometry study / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to evaluate the surface roughness (SR) of 2 types of orthodontic archwires made by 4 different manufacturers. METHODS: This in vitro experimental study was conducted on 35 specimens of 7 different orthodontic archwires, namely, 1 nickel-titanium (NiTi) archwire each from the manufacturers American Orthodontics, OrthoTechnology, All-Star Orthodontics, and Smart Technology, and 1 stainless steel (SS) archwire each from the manufacturers American Orthodontics, OrthoTechnology, and All-Star Orthodontics. After analyzing the composition of each wire by energy-dispersive X-ray analysis, the SR of each wire was determined by scanning electron microscopy (SEM) and surface profilometry. Data were analyzed using the Kruskal-Wallis and Mann-Whitney U tests (alpha < 0.05). RESULTS: The average SR of NiTi wires manufactured by Smart Technology, American Orthodontics, OrthoTechnology, and All-Star Orthodontics were 1,289 +/- 915 Adegrees, 1,378 +/- 372 Adegrees, 2,444 +/- 369 Adegrees, and 5,242 +/- 2,832 Adegrees, respectively. The average SR of SS wires manufactured by All-Star Orthodontics, OrthoTechnology, and American Orthodontics were 710 +/- 210 Adegrees, 1,831 +/- 1,156 Adegrees, and 4,018 +/- 2,214 Adegrees, respectively. Similar to the results of profilometry, the SEM images showed more defects and cracks on the SS wire made by American Orthodontics and the NiTi wire made by All-Star Orthodontics than others. CONCLUSIONS: The NiTi wire manufactured by All-Star Orthodontics and the SS wire made by American Orthodontics were the roughest wires.

Association between periodontal pathogens and coronary artery disease: a case-control study

We sought to answer the questions about the role of inflammatory factors in the formation of pathological lesions in the endothelium of the coronary vessels and also the role of host-based bacteria, including chronic periodontitis, in the clot formation in the blood vessels, all of which destabilize the atherosclerotic plaque. This case-control study was done on 40 patients who underwent elective coronary artery bypass grafting surgery [CABG] with the need of coronary endarterectomy. In Group A, patients had chronic periodontitis and group B consisted of patients without it. Both groups were well matched regarding their demographic data. The subgingival plaque was collected by a sterile curette from periodontal pockets >/= 5mm and CAL >/= 4mm. Also, atherosclerotic plaque was collected during the coronary endarterectomy surgery from all of the 40 patients. The specimens were assessed using the PCR technique to detect the specific bacteria responsible for chronic periodontitis such as actinobacillus actinomycetemcomitans [Aa], prevotella intermedia [Pi], porphyromonas gingivalis [Pg], Tanerella forsythensis [Tf], Treponema denticola [Td], and fusobacterium nucleatum [Fn]. In the atherosclerotic plaque of group A patients, Aa was identified in 18 [90%], Pg in 16 [80%], Tf in 13[65%],Td in 11 [55%], Pi in 10 [50%], and Fn in 6 [30%] specimens, whereas in group B the incidence was significantly lower [p< 0.0001]. In the subgingival plaque of group A, Aa and Tf were found in all 20 individuals and Pg, Pi, Td and Fn were identified in 19 specimens [95%]. The differences in the incidence of Aa and Pg in two plaque samples were not significant, but the two plaque samples showed significant differences regarding the incidence of the other pathogens [Pi: p<0.001, Tf: p<0.008, Td: p<0.003 and Fn :p<0.0001]. In the present study, the same organisms were found in both coronary atherosclerotic and subgingival plaques. The findings support the potential role of the periodontopathogenic bacteria species in some steps of the atherosclerotic process as a contributor that worsens this disease. However, further studies are required to achieve more definite results regarding the role of periodontal diseases in the atherosclerotic disease, focusing on patients' background variables

Isolation and in vitro characterization of mesenchymal stem cells derived from the pulp tissue of human third molar tooth

It is still controversial that the stem cells isolated from human dental pulp meets the criteria for mesenchymal stem cells [MSCs]. The aim of the present study was to examine whether or not they are MSCs, or are distinct stem cells population residing in tooth pulp. Adherent fibroblastic cells in the culture of pulp tissue from human third molars were propagated through several successive subcultures. Passaged-3 cells with a tendency to differentiate into odontoblastic cells were used to examine the key properties of MSCs including typical tripotent differentiation potential into bone, cartilage and adipose cell lineages and the expression of typical surface antigens. Moreover, they were examined for growth capacity in culture. Dental pulp stem cells successfully progressed towards differentiation among three skeletal cell lineages. More than 90% of the cell population exhibited the expression of surface antigens known to be found on mesenchymal lineages such as CD105, CD90, CD44, and CD73, while only less than 2% expressed endothelial-hematopoietic epitopes including CD56, CDllb, CD34, CD31, CD33, and CD45. The cells exhibited a relatively high proliferation capacity with population doubling time of about 21.9 hours. The dental pulp stem cells are of MSC population, and may be considered suitable for use in regenerative medicine, owing to their relatively rapid rate of in vitro propagation