Survey of the use of statistical methods in Journal of the Korean Association of Oral and Maxillofacial Surgeons

OBJECTIVES: This study aimed to describe recent patterns in the types of statistical test used in original articles that were published in Journal of the Korean Association of Oral and Maxillofacial Surgeons. MATERIALS AND METHODS: Thirty-six original articles published in the Journal in 2015 and 2016 were ascertained. The type of statistical test was identified by one researcher. Descriptive statistics, such as frequency, rank, and proportion, were calculated. Graphical statistics, such as a histogram, were constructed to reveal the overall utilization pattern of statistical test types. RESULTS: Twenty-two types of statistical test were used. Statistical test type was not reported in four original articles and classified as unclear in 5%. The four most frequently used statistical tests constituted 47% of the total tests and these were the chi-square test, Student's t-test, Fisher's exact test, and Mann-Whitney test in descending order. Regression models, such as the Cox proportional hazard model and multiple logistic regression to adjust for potential confounding variables, were used in only 6% of the studies. Normality tests, including the Kolmogorov-Smirnov test, Levene test, Shapiro-Wilk test, and Scheffé's test, were used diversely but in only 10% of the studies. CONCLUSION: A total of 22 statistical tests were identified, with four tests occupying almost half of the results. Adoption of a nonparametric test is recommended when the status of normality is vague. Adjustment for confounding variables should be pursued using a multiple regression model when the number of potential confounding variables is numerous.

Survey of the use of statistical methods in Journal of the Korean Association of Oral and Maxillofacial Surgeons

OBJECTIVES@#This study aimed to describe recent patterns in the types of statistical test used in original articles that were published in Journal of the Korean Association of Oral and Maxillofacial Surgeons.@*MATERIALS AND METHODS@#Thirty-six original articles published in the Journal in 2015 and 2016 were ascertained. The type of statistical test was identified by one researcher. Descriptive statistics, such as frequency, rank, and proportion, were calculated. Graphical statistics, such as a histogram, were constructed to reveal the overall utilization pattern of statistical test types.@*RESULTS@#Twenty-two types of statistical test were used. Statistical test type was not reported in four original articles and classified as unclear in 5%. The four most frequently used statistical tests constituted 47% of the total tests and these were the chi-square test, Student's t-test, Fisher's exact test, and Mann-Whitney test in descending order. Regression models, such as the Cox proportional hazard model and multiple logistic regression to adjust for potential confounding variables, were used in only 6% of the studies. Normality tests, including the Kolmogorov-Smirnov test, Levene test, Shapiro-Wilk test, and Scheffé's test, were used diversely but in only 10% of the studies.@*CONCLUSION@#A total of 22 statistical tests were identified, with four tests occupying almost half of the results. Adoption of a nonparametric test is recommended when the status of normality is vague. Adjustment for confounding variables should be pursued using a multiple regression model when the number of potential confounding variables is numerous.

The conquest of errors

No abstract available.

The current problem with journal review systems

No abstract available.

Clinical statistics: five key statistical concepts for clinicians

Statistics is the science of data. As the foundation of scientific knowledge, data refers to evidentiary facts from the nature of reality by human action, observation, or experiment. Clinicians should be aware of the conditions of good data to support the validity of clinical modalities in reading scientific articles, one of the resources to revise or update their clinical knowledge and skills. The cause-effect link between clinical modality and outcome is ascertained as pattern statistic. The uniformity of nature guarantees the recurrence of data as the basic scientific evidence. Variation statistics are examined for patterns of recurrence. This provides information on the probability of recurrence of the cause-effect phenomenon. Multiple causal factors of natural phenomenon need a counterproof of absence in terms of the control group. A pattern of relation between a causal factor and an effect becomes recognizable, and thus, should be estimated as relation statistic. The type and meaning of each relation statistic should be well-understood. A study regarding a sample from the population of wide variations require clinicians to be aware of error statistics due to random chance. Incomplete human sense, coarse measurement instrument, and preconceived idea as a hypothesis that tends to bias the research, which gives rise to the necessity of keen critical independent mind with regard to the reported data.

A head and two wings: essential parts of world-class international journal

No abstract available.

A 15-year clinical retrospective study of Branemark implants / 대한치과보철학회지

PURPOSE: This study was to compare the cumulative survival rate (CSR) of Branemark machined surface implants and TiUnite(TM) imlants and to analyze association between risk factors and the CSR of the implants. MATERIALS AND METHODS: A retrospective study design was used to collect long-term follow-up clinical data from dental records of 156 patients treated with 541 Branemark machined and TiUnite(TM) implants at Korea University Guro hospital in South Korea from 1993 through 2008. Machined implant and TiUnite(TM) implant were compared by CSR. Exposure variables such as gender, systemic disease, location, implant length, diameter, prosthesis type, opposing occlusion type, date of implant placement, type of edentulous space, abutment type, existence of splinting with natural teeth, and existence of cantilever were collected. Life table analysis was undertaken to examine the CSR. Cox regression method was conducted to assess the association between potential risk factors and overall CSR (alpha=.05). RESULTS: Patient ages ranged from 16 to 75 years old (mean age, 51 years old). Implants were more frequently placed in men than women (94 men versus 63 women). Since 1993, 264 Branemark machined implants were inserted in 79 patients and since 2001, 277 TiUnite(TM) implants were inserted in 77 patients. A total survival rate of 86.07% was observed in Branemark and Nobel Biocare TiUnite(TM) during 15 years. A survival rate of machined implant during 15 years was 82.89% and that of TiUnite(TM) implant during 5 years was 98.74%. The implant CSR revealed lower rates association with several risk factors such as, systemic disease, other accompanied surgery, implant location, and Kennedy classification. CONCLUSION: Clinical performance of Branemark machined and TiUnite(TM) implant demonstrated a high level of predictability. In this study, TiUnite(TM) implant was more successful than machined implant. The implant CSR was associated with several risk factors.

A 5-year retrospective clinical study of the Dentium implants

PURPOSE: The aim of this retrospective study was to evaluate cumulative survival rate (CSR) of Implantium implants followed for 5 years and association between risk factors and the CSR. MATERIALS AND METHODS: A total of two hundred forty-nine Implantium Implants System (Dentium, Seoul, Korea) placed in ninety-five patients from 2004 to 2009 were investigated with several identified risk factors (sex, systemic disease, smoking, alchohol, reason of tooth loss, length, arch (maxilla or mandible), replace tooth type (incisor, canine, premolar or molar) Kennedy classification, prosthodontic type, prosthodontic design, opposite dentition, abutment type, occlusal material, occlusal unit, splint to tooth, cantilever, other surgery). Clinical examination (mobility, percussion, screw loosening, discomfort, etc.) and radiographic examination data were collected from patient records including all problems during follow-up period according to protocols described earlier. Life table analysis was undertaken to examine the CSR. Cox regression method was conducted to assess the association between potential risk factors and overall CSR. RESULTS: Five of 249 implants were failed. Four of these were lost before loading. The 5-year implant cumulative survival rate was 97.37%. Cox regression analysis demonstrated a significant predictive association between overall CSR and systemic disease, smoking, reason of tooth loss, arch, Kennedy classification and prosthodontic design (P<.05). The screw related complication was rare. Two abutment screw fractures were found. Another complications of prosthetic components were porcelain fracture, resin facing fracture and denture fracture (n=19). CONCLUSION: The 5-year CSR of Implantium implants was 97.37%. Implant survival may be dependent upon systemic disease, smoking reason of tooth loss, arch, Kennedy classification and prosthodontic design (P<.05). The presence of systemic diseases and combination of other surgical procedures may be associated with increased implant failure.

An assessment of statistical errors of articles in the Journal of Korean Academy of Prosthodontics: Comparison between Korean version and English version / 대한치과보철학회지

STATEMENT OF PROBLEM: The aim of dental research is to advance scientific knowledge and leads to improvement in the treatment and prevention of dental disease. Utilizing an effective research design and adequate statistical methods are essential procedures ensuring that the results of researches are based on evidences. A research should utilize proper statistical methods without statistical errors; Otherwise, it could adversely affect clinical practice and future research. PURPOSE: This study was made to investigate the statistical methods used in the Journal of Korean Academy of Prosthodontics (JKAP) and then to assess them for the statistical errors. MATERIAL AND METHODS: Among the total of 399 articles in the JKAP published from 2000 to 2006, 292 articles using statistics were reviewed. The validity of the statistical methods used in them were assessed using a checklist based on the guideline for statistical reporting in the uniform requirements for manuscripts submitted to biomedical journals by International Committee of Medical Journal Editors. The checklist consisted of three categories of statistical errors: 1) Unspecified computer statistical packages, 2) Inadequate description of statistical methods, 3) Misuse of statistical terms. Then, the results were compared between the Korean version and the English version in the JKAP. RESULTS: Among the 212 articles using statistics in the Korean version, 115 articles (54%) and among the 80 articles using statistics in the English version, 47 articles (59%) were shown to have unspecified computer statistical packages without statistically significant difference (P = .66). Likewise, 101 articles (48%) in the Korean version and 25 articles (31%) in the English version were shown to have the inadequate description of statistical methods without statistically significant difference (P = .09). However, 114 articles (54%) in the Korean version and 19 articles (24%) in the English version were shown to have the misuse of statistical terms with statistically significant difference (P = .01). CONCLUSION: Some of the articles in the JKAP had inadequate statistical validity, given the statistical errors identified in this assessment. Hence, dental researchers should be more careful when it comes to describing and applying statistical methods.

The kinds and impact of demographic and clinical factors associated with stress of patients going through maxillofacial surgery

Surgical process of oral and maxillofacial area as well as dental treatment are stressful situations to the patients. It is well known that serum level of stress hormones including adrenocorticotropic hormone(ACTH) and cortisol increase when the body is exposed to stress. However, there have been few studies on demographic and clinical factors related with stress. Therefore, the purpose of this study was to supply data to cope with stress more comprehensively and efficiently by analyzing the effect of factors related with stress in addition to surgical procedure. Prospective cohort study method was selected. Serum levels of ACTH and cortisol were measured by sampling bloods pre-operatively and post-operatively from 45 patients who had been operated at the Bundang Jesaeng Hospital department of oral and maxillofacial surgery. To evaluate factors associated with stress, patients were classified according to gender, age, method of payment(insurance or self), experiences of operation, kind of operations(expected operations or unexpected operations). Relative risk was calculated to assess relationships between changes of serum level of ACTH and cortisol and factors related with stress, whereas Chi-square analysis was executed to evaluate statistical significance. With regard to serum level of ACTH, relative risk was 1.3 in the group of the patients who were less than 40 years old. With regard to serum level of cortisol, relative risk was 1.8 for women compared with men, 1.4 in the group of the patients who were less than 40 years old and 1.6 in the group of the patients who had not experienced any other operations. In addition to surgical procedure, factors related with stress included gender, age, method of payments, experiences of operation and kind of operations. Therefore, we should provide comprehensive schemes to reduce stress of the patients going through oral and maxillofacial surgery.