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2.  Statistical methods used in articles published by the Journal of Periodontal and Implant Science 
The purposes of this study were to assess the trend of use of statistical methods including parametric and nonparametric methods and to evaluate the use of complex statistical methodology in recent periodontal studies.
This study analyzed 123 articles published in the Journal of Periodontal & Implant Science (JPIS) between 2010 and 2014. Frequencies and percentages were calculated according to the number of statistical methods used, the type of statistical method applied, and the type of statistical software used.
Most of the published articles considered (64.4%) used statistical methods. Since 2011, the percentage of JPIS articles using statistics has increased. On the basis of multiple counting, we found that the percentage of studies in JPIS using parametric methods was 61.1%. Further, complex statistical methods were applied in only 6 of the published studies (5.0%), and nonparametric statistical methods were applied in 77 of the published studies (38.9% of a total of 198 studies considered).
We found an increasing trend towards the application of statistical methods and nonparametric methods in recent periodontal studies and thus, concluded that increased use of complex statistical methodology might be preferred by the researchers in the fields of study covered by JPIS.
Graphical Abstract
PMCID: PMC4284377  PMID: 25568809
Nonparametric statistics; Periodontal diseases; Statistical data interpretation; Statistics
6.  Accuracy and precision of polyurethane dental arch models fabricated using a three-dimensional subtractive rapid prototyping method with an intraoral scanning technique 
Korean Journal of Orthodontics  2014;44(2):69-76.
This study aimed to evaluate the accuracy and precision of polyurethane (PUT) dental arch models fabricated using a three-dimensional (3D) subtractive rapid prototyping (RP) method with an intraoral scanning technique by comparing linear measurements obtained from PUT models and conventional plaster models.
Ten plaster models were duplicated using a selected standard master model and conventional impression, and 10 PUT models were duplicated using the 3D subtractive RP technique with an oral scanner. Six linear measurements were evaluated in terms of x, y, and z-axes using a non-contact white light scanner. Accuracy was assessed using mean differences between two measurements, and precision was examined using four quantitative methods and the Bland-Altman graphical method. Repeatability was evaluated in terms of intra-examiner variability, and reproducibility was assessed in terms of inter-examiner and inter-method variability.
The mean difference between plaster models and PUT models ranged from 0.07 mm to 0.33 mm. Relative measurement errors ranged from 2.2% to 7.6% and intraclass correlation coefficients ranged from 0.93 to 0.96, when comparing plaster models and PUT models. The Bland-Altman plot showed good agreement.
The accuracy and precision of PUT dental models for evaluating the performance of oral scanner and subtractive RP technology was acceptable. Because of the recent improvements in block material and computerized numeric control milling machines, the subtractive RP method may be a good choice for dental arch models.
PMCID: PMC3971128  PMID: 24696823
Three-dimensional subtractive rapid prototyping; Intraoral scanning; Accuracy; Precision
7.  Analysis of variance (ANOVA) comparing means of more than two groups 
PMCID: PMC3916511  PMID: 24516834
11.  Peri-implant bone length changes and survival rates of implants penetrating the sinus membrane at the posterior maxilla in patients with limited vertical bone height 
The aim of this study was to measure the peri-implant bone length surrounding implants that penetrate the sinus membrane at the posterior maxilla and to evaluate the survival rate of these implants.
Treatment records and orthopantomographs of 39 patients were reviewed and analyzed. The patients had partial edentulism at the posterior maxilla and limited vertical bone height below the maxillary sinus. Implants were inserted into the posterior maxilla, penetrating the sinus membrane. Four months after implant insertion, provisional resin restorations were temporarily cemented to the abutments and used for one month. Then, a final impression was taken at the abutment level, and final cement-retained restorations were delivered with mutually protected occlusion. The complications from the implant surgery were examined, the number of failed implants was counted, and the survival rate was calculated. The peri-implant bone lengths were measured using radiographs. The changes in initial and final peri-implant bone lengths were statistically analyzed.
Nasal bleeding occurred after implant surgery in three patients. No other complications were found. There were no failures of the investigated implants, resulting in a survival rate of 100%. Significantly more bone gain around the implants (estimated difference=-0.6 mm, P=0.025) occurred when the initial residual bone height was less than 5 mm compared to the >5 mm groups. No significant change in peri-implant bone length was detected when the initial residual bone height was 5 mm or larger.
This study suggests that implants penetrating the sinus membrane at the posterior maxilla in patients with limited vertical bone height may be safe and functional.
PMCID: PMC3651938  PMID: 23678388
Biomechanics; Biostatistics; Maxilla; Maxillary sinus; Sinus floor augmentation
13.  Statistical notes for clinical researchers: assessing normal distribution (1) 
PMCID: PMC3568647  PMID: 23431506
14.  Des-gamma-carboxy Prothrombin and Alpha fetoprotein as Biomarkers for the Early Detection of Hepatocellular Carcinoma 
Gastroenterology  2009;138(2):493.
Background and Aims:
The outcome of patients with hepatocellular carcinoma (HCC) remains poor because of late diagnosis. The aim of this study was to compare the accuracy of alpha fetoprotein (AFP) and des-gamma-carboxy prothrombin (DCP) in the early diagnosis of HCC.
Among 1031 patients randomized in the Hepatitis C Antiviral Long-Term Treatment against Cirrhosis (HALT-C) Trial, a nested case-control study of 39 HCC cases (24 early stage) and 77 matched controls was conducted to compare the performance of AFP and DCP. Testing was performed on sera from 12 months prior (month −12) to the time of HCC diagnosis (month 0).
The sensitivity and specificity of DCP at month 0 was 74% and 86% at a cutoff of 40 mAU/mL and 43% and 100% at a cutoff of 150 mAU/mL. The sensitivity and specificity of AFP at month 0 was 61% and 81% at a cutoff of 20 ng/mL and 22% and 100% at a cutoff of 200 ng/mL. At month −12, the sensitivity and specificity at the low cutoff was 43% and 94% for DCP and 47% and 75% for AFP. Combining both markers increased the sensitivity to 91% at month 0 and 73% at month 12 but the specificity decreased to 74% and 71%. Diagnosis of early HCC was triggered by surveillance ultrasound in 14, doubling of AFP in 5 and combination of tests in 5 patients.
Biomarkers are needed to complement ultrasound in the detection of early HCC but neither DCP nor AFP is optimal.
PMCID: PMC2819612  PMID: 19852963
hepatitis C; interferon; cirrhosis
15.  Hemoglobin H-constant spring in North America: an alpha Thalassemia with frequent complications 
American journal of hematology  2009;84(11):759-761.
Hemoglobin H-constant spring (Hb H-CS), the most common nondeletional alpha thalassemia in Asia is increasingly recognized in North America due to shifts in immigration patterns. In California, alpha (α)-thalassemia syndromes are the second most frequent finding among newborns screened for hemoglobinopathies with a two-fold increase compared to a decade earlier [1,2]. Though known to have a more severe anemia than Hb H disease, the other clinical findings of Hb H-CS are not well described. Moreover, beneficial therapies that have become available in the last decade are often not applied to their care. This analysis of 46 patients enrolled in the Thalassemia Clinical Research Network (TCRN) age 13+/− 10 years old, with Hb H-CS revealed moderate anemia (mean 8.7 ± 1.5 g/dl), regular transfusion therapy in 24% of patients, and splenomegaly or prior splenectomy in one-third of them. Serum transferin receptor (sTfr), was elevated; (44.4 ± 18 mcg/ml normal range 2.9–8.3 mcg/ml), reflecting ineffective erythropoiesis, which in turn leads to high iron absorption and increased ferritin levels in younger (median = 187 ng/ml) and older (median = 465 ng/ml) nontransfused patients. These findings along with moderate growth delay and low bone mass were more prevalent in Hb H-CS patients compared to deletional Hb H disease. Our results highlight the required monitoring of the extent of anemia, growth, splenomegaly, iron overload, gallstones, bone density and assessment of need for transfusions and specific treatments for disease complications.
PMCID: PMC4254706  PMID: 19787795
16.  Human Milk Galectin-3 Binding Protein and Breastfeeding-Associated HIV Transmission 
Analysis of milk from 247 HIV-infected Zambian mothers showed that Galectin-3 Binding Protein (Gal3BP) concentrations were significantly higher among HIV-infected mothers who transmitted HIV through breastfeeding (6.51±2.12 ug/mL) than among non-transmitters but were also correlated with higher milk and plasma HIV RNA copies/ml and lower CD4+ cell counts. The association between Gal3BP and postnatal transmission was attenuated after adjustment for milk and plasma HIV load and CD4+ cell counts. This suggests that although milk Gal3BP is a marker of advanced maternal disease, it does not independently modify transmission risk.
PMCID: PMC3907473  PMID: 23899964
HIV transmission; breastfeeding; Galectin-3 Binding Protein; oral transmission
17.  Renal dysfunction in patients with thalassaemia 
British journal of haematology  2011;153(1):111-117.
Little is known about the effects of thalassaemia on the kidney. Characterization of underlying renal function abnormalities in thalassaemia is timely because the newer iron chelator, deferasirox, can be nephrotoxic. We aimed to determine the prevalence and correlates of renal abnormalities in thalassaemia patients, treated before deferasirox was widely available, using 24-h collections of urine. We calculated creatinine clearance and urine calcium-to-creatinine ratio and measured urinary β2-microglobulin, albumin, and protein. We used multivariate modelling to identify clinical, therapeutic, and laboratory predictors of renal dysfunction. One-third of thalassaemia patients who were not regularly transfused had abnormally high creatinine clearance. Regular transfusions were associated with a decrease in clearance (P = 0·004). Almost one-third of patients with thalassaemia had hypercalciuria, and regular transfusions were associated with an increase in the frequency and degree of hypercalciuria (P < 0·0001). Albuminuria was found in over half of patients, but was not consistently associated with transfusion therapy. In summary, renal hyperfiltration, hypercalciuria, and albuminuria are common in thalassaemia. Higher transfusion intensity is associated with lower creatinine clearance but more frequent hypercalciuria. The transfusion effect needs to be better understood. Awareness of underlying renal dysfunction in thalassaemia can inform decisions now about the use and monitoring of iron chelation.
PMCID: PMC4250090  PMID: 21332704
thalassaemia; kidney; creatinine clearance; hyperfiltration; hypercalciuria; albuminuria; proteinuria; transfusion
18.  Accuracy of 3D white light scanning of abutment teeth impressions: evaluation of trueness and precision 
This study aimed to evaluate the accuracy of digitizing dental impressions of abutment teeth using a white light scanner and to compare the findings among teeth types.
To assess precision, impressions of the canine, premolar, and molar prepared to receive all-ceramic crowns were repeatedly scanned to obtain five sets of 3-D data (STL files). Point clouds were compared and error sizes were measured (n=10 per type). Next, to evaluate trueness, impressions of teeth were rotated by 10°-20° and scanned. The obtained data were compared with the first set of data for precision assessment, and the error sizes were measured (n=5 per type). The Kruskal-Wallis test was performed to evaluate precision and trueness among three teeth types, and post-hoc comparisons were performed using the Mann-Whitney U test with Bonferroni correction (α=.05).
Precision discrepancies for the canine, premolar, and molar were 3.7 µm, 3.2 µm, and 7.3 µm, respectively, indicating the poorest precision for the molar (P<.001). Trueness discrepancies for teeth types were 6.2 µm, 11.2 µm, and 21.8 µm, respectively, indicating the poorest trueness for the molar (P=.007).
In respect to accuracy the molar showed the largest discrepancies compared with the canine and premolar. Digitizing of dental impressions of abutment teeth using a white light scanner was assessed to be a highly accurate method and provided discrepancy values in a clinically acceptable range. Further study is needed to improve digitizing performance of white light scanning in axial wall.
PMCID: PMC4279045  PMID: 25551007
White light scanner; Accuracy; Precision and trueness; Impression scanning; 3D shape data; Point cloud
19.  Inflammatory and Tissue Remodeling Urinary Biomarkers Before and After Midurethral Sling Surgery for Stress Urinary Incontinence 
The Journal of urology  2013;191(3):703-709.
Urinary biomarkers were measured from women at baseline and 1 post-surgery for stress urinary incontinence (SUI) and associations with clinicodemographic covariates and outcomes were analyzed.
Pre- and post-surgery urine specimens from 150 women were assayed for inflammatory biomarkers (TNF-α, IFN-γ, IL-1β, IL6, IL10, IL12p70, IL17, NGF) and tissue remodeling biomarkers (collagenase activity, MMPs-1, 2, 9, 13, N-telopeptide cross-linked collagen (NTx), EGF, HB-EGF). Paired t-tests compared changes in biomarker over 1 year (significance p<0.05). Linear regression models correlated baseline and changes in biomarker levels with covariates (significance p≤0.001). Logistic regression models, controlling for age, analyzed associations of baseline and changes in biomarker levels with surgical failure (significance p<0.05).
Over one year, IL12p70 decreased (0.53±1.4 to 0.28±.62 pg/mg Cr, p=0.04) and NGF increased (0.034 ± 0.046 to 0.044 ± 0.060 pg/ml/mOsm, p=0.03). Baseline NTx level/mg Cr was positively associated with age and post-menopausal status (p=0.001), and negatively associated with current estrogen use (p=0.0001). Baseline collagenase activity/mg Cr was positively associated with age (p=0.001). EGF/mOsm, NTx/mOsm and IFN-γ/mOsm were negatively correlated with age, current estrogen use, and UDI-irritative score, respectively (p≤0.001). Subjects with lower baseline NTx/mg Cr were less likely to experience surgical failure (OR 0.49, 95% CI 0.26, 0.93, p=0.03). Changes in biomarker levels were neither associated with any covariates nor surgical failure.
Women with lower baseline NTx levels were significantly less likely to fail SUI surgery. Studies are needed to validate NTx as a possible independent biomarker for SUI surgery outcomes.
PMCID: PMC4183133  PMID: 24140551
21.  How to design in situ studies: an evaluation of experimental protocols 
Designing in situ models for caries research is a demanding procedure, as both clinical and laboratory parameters need to be incorporated in a single study. This study aimed to construct an informative guideline for planning in situ models relevant to preexisting caries studies.
Materials and Methods
An electronic literature search of the PubMed database was performed. A total 191 of full articles written in English were included and data were extracted from materials and methods. Multiple variables were analyzed in relation to the publication types, participant characteristics, specimen and appliance factors, and other conditions. Frequencies and percentages were displayed to summarize the data and the Pearson's chi-square test was used to assess a statistical significance (p < 0.05).
There were many parameters commonly included in the majority of in situ models such as inclusion criteria, sample sizes, sample allocation methods, tooth types, intraoral appliance types, sterilization methods, study periods, outcome measures, experimental interventions, etc. Interrelationships existed between the main research topics and some parameters (outcome measures and sample allocation methods) among the evaluated articles.
It will be possible to establish standardized in situ protocols according to the research topics. Furthermore, data collaboration from comparable studies would be enhanced by homogeneous study designs.
PMCID: PMC4125579  PMID: 25110639
In situ; Caries; Demineralization; Remineralization; Erosion; Materials and methods
22.  Bond and fracture strength of metal-ceramic restorations formed by selective laser sintering 
The purpose of this study was to compare the fracture strength of the metal and the bond strength in metal-ceramic restorations produced by selective laser sintering (SLS) and by conventional casting (CAST).
Non-precious alloy (StarLoy C, DeguDent, Hanau, Germany) was used in CAST group and metal powder (SP2, EOS GmbH, Munich, Germany) in SLS group. Metal specimens in the form of sheets (25.0 × 3.0 × 0.5 mm) were produced in accordance with ISO 9693:1999 standards (n=30). To measure the bond strength, ceramic was fired on a metal specimen and then three-point bending test was performed. In addition, the metal fracture strength was measured by continuing the application of the load. The values were statistically analyzed by performing independent t-tests (α=.05).
The mean bond strength of the SLS group (50.60 MPa) was higher than that of the CAST group (46.29 MPa), but there was no statistically significant difference. The metal fracture strength of the SLS group (1087.2 MPa) was lower than that of the CAST group (2399.1 MPa), and this difference was statistically significant.
In conclusion the balling phenomenon and the gap formation of the SLS process may increase the metal-ceramic bond strength.
PMCID: PMC4146726  PMID: 25177469
Selective laser sintering; Metal-ceramic restoration; Bond strength; Fracture strength; Balling phenomenon
23.  Ten-Year Effects of the ACTIVE Cognitive Training Trial on Cognition and Everyday Functioning in Older Adults 
To determine the effects of cognitive training on cognitive abilities and everyday function over 10 years.
Design, Setting, and Participants
Ten-year follow-up of a randomized, controlled single-blind trial with 3 intervention groups and a no-contact control group. A volunteer sample of 2832 persons (mean baseline age, 73.6 years; 26% African American) living independently in 6 US cities.
Ten-session training for memory, reasoning, or speed-of-processing.; 4-session booster training at 11 and at 35 months after training.
Objectively measured cognitive abilities and self-reported and performance-based measures of everyday function.
Participants in each intervention group reported less difficulty with instrumental activities of daily living (IADL) (memory: effect size, 0.48 [99% CI, 0.12-0.84]; reasoning: effect size, 0.38 [99% CI, 0.02-0.74]; speed-of-processing: effect size, 0.36 [99% CI, 0.01-0.72]). At mean age of 82 years, about 60% of trained participants compared to 50% of controls (p<.05) were at or above their baseline level of self-reported IADL function at 10 years. The reasoning and speed-of-processing interventions maintained their effects on their targeted cognitive abilities at 10 years (reasoning: effect size, 0.23 [99% CI, 0.09-0.38]; speed-of-processing: effect size, 0.66 [99% CI, 0.43-0.88]). Memory training effects were no longer maintained for memory performance. Booster training produced additional and durable improvement for the reasoning intervention for reasoning performance (effect size, 0.21 [99% CI, 0.01-0.41]) and the speed-of-processing intervention for speed-of-processing performance (effect size, 0.62 [99% CI, 0.31-0.93]).
Each ACTIVE cognitive intervention resulted in less decline in self-reported IADL compared with the control group. Reasoning and speed, but not memory, training resulted in improved targeted cognitive abilities for 10 years.
PMCID: PMC4055506  PMID: 24417410
cognitive training; elderly; cognitive abilities; everyday function; training maintenance
24.  Two Cases of Infantile Intra-abdominal Inflammatory Myofibroblastic Tumor 
Inflammatory myofibroblastic tumor (IMT) is rare mesenchymal solid tumor that consists of proliferating myofibroblasts with an inflammatory infiltrate background. It has a very low prevalence in infants and occurs mainly in children and young adults. IMT are mainly located in the thoracic cavity, but intra-abdominal lesions are rare. IMT can exhibit locally aggressive neoplastic processes and metastases similar to malignancies, so, have clinical importance. Herein, we describe two infantile intra-abdominal IMT cases presenting with incidentally found palpable abdominal mass. A 4-month-old male infant had IMT at the ileal mesentery and a 5-month-old male infant had IMT at liver. Both cases were successfully treated by complete surgical resection without complication or recurrence. Considering the biological behavior of the intermediate type of neoplasm in IMT, we expect good survivals when achieving appropriate surgical resection without adjuvant therapy in infantile intra-abdominal IMT.
PMCID: PMC4107219  PMID: 25061588
Inflammatory myofibroblastic tumor; Intraabdominal; Infant
25.  Fundoplication in Neonates and Infants with Primary Gastroesophageal Reflux 
Gastroesophageal reflux in infant is a physiological process. However, surgery is performed in high risk infants with severe gastroesophageal reflux disease (GERD) when medical management fails. This study focuses on efficacy and safety of Nissen fundoplication for GERD in infants under age 12 months.
This study was a retrospective case analysis of 11 neonates and infants under 12 months of age who underwent Nissen fundoplication following a failure of medical treatment between June 2010 and June 2013 at Pusan National University Children's Hospital. The records were reviewed to determine the effect of fundoplication on symptoms and post-operative complications.
A total of 11 infants consist of four males and seven females. Mean birth weight was 2,305.5±558.6 g (1,390-3,130 g). They had some underlying disease, which are not related with GERD such as congenital heart disease (54.5%), prematurity (45.5%), neurologic disease (18.2%), respiratory disease (18.2%), and other gastrointestinal disease. Mean body weight at surgery was 3,803.6±1,864.9 g (1,938.7-5,668.5 g). Mean age at operation was 99.9±107.6 days (17-276 days). Duration from operation to full enteral feeding was 10.9 days. Symptoms related GERD disappeared in all patients including one who got reoperation. One infant died of congenital heart disease unrelated to surgery. There were no complications related to fundoplication.
Fundoplication is effective and safe treatment in the neonates and infants with severe GERD.
PMCID: PMC4107226  PMID: 25061584
Gastroesophageal reflux; Fundoplication; Infant

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