pain affects all aspects of a person 's life including sleep , work , leisure and 
 relationships .
it impacts on the lives of sufferers by causing limitations in daily 
 life and this in turn imposes a huge burden on society , due to the high direct costs 
 of treatment and indirect costs from lost productivity [ 1 - 4 ] .
approaches to the measurement of pain 
 include verbal and numeric self - rating scales , behavioural observation scales , and 
 physiologic responses . because of complex nature of the experience of pain and its 
 subjective characteristic ,
self - reported measures of oral health 
 quality of life relate altered functions and symptoms to social and psychological 
 well - being .
however , different oral conditions may affect functioning and physical 
 and emotional problems in different ways and therefore disease specific instruments 
 may be invaluable in investigating the impact of these conditions on 
 individuals .
brazilian studies about disabilities caused by orofacial pain use rdc / tmd ( research 
 diagnostic criteria for temporomandibular disorders ) axis ii , oidp ( oral impact 
 daily performance ) , ohip ( oral health impact profile ) , ghq-12 ( general health 
 questionnaire ) and brazilian version of mcgill pain questionnaire .
although these 
 tools were not specifically developed to assess orofacial pain related disability , 
 they all concluded that oro - facial pain imposes a huge burden on the daily life of 
 sufferers [ 7 - 9 ] .
the manchester orofacial pain disability scale ( mopds ) construction and validation 
 has been previously demonstrated .
this tool has been shown to be robust in measuring 
 orofacial pain related disability and had good construct validity . with
the increasing number of international research projects , the need to adapt 
 measures of health status to use the language of origin has grown rapidly .
most 
 questionnaires were developed in english - speaking countries , but even within those 
 countries , researchers should consider translating these for immigrants , especially 
 when their exclusion may lead to systematic bias in studies of health care related 
 quality of life .
recommend cross - cultural adaptation in addition to simple translation for 
 questionnaires of health status that are going to be used in a different language 
 and culture from which they were originally developed .
this paper therefore aims to adapt the manchester orofacial pain disability scale to 
 a portuguese language version through a formal translation / back - translation process 
 and summarize available data about its psychometric properties .
specific objectives were to determine the internal consistency and reliability of the 
 translated scale and to validate its use for measuring orofacial pain specific 
 disability in brazilian patients .
the guidelines for translation and cross - cultural adaptation process ( beaton et al . 
  and wild et al .  
were used following the stages above : stage i : initial translation two independent translations from english to portuguese were made by two bilingual 
 translators whose mother tongue is the portuguese language in order to accurately 
 reflect the nuances of the language .
both translators had different profiles or 
 backgrounds - one with academic vinculum ( with theme knowledge ) and the second one a 
 clinical dentist .
stage ii : synthesis of the translations a synthesis of these translations was first conducted ( producing one common 
 translation ) by the authors of the research and two non - native english language 
 teachers .
stage iii : back translation working from the synthesis of the translated versions and totally blind to the 
 original version , two different non - native english language teachers without dental 
 knowledge translated the questionnaire back to the english language .
stage iv : expert committee an expert committee reviewed the pre - final version : the researchers , two other 
 non - native english language teachers and one native english speaking professor .
stage v : test of the prefinal version this field test of the new questionnaire was used in 8 patients from the target 
 setting .
each subject completed the questionnaire and was interviewed to probe what 
 he or she believed to be the meaning of each questionnaire item and its response . in 
 this stage these patients suggested to exclude the question " i am irritable , 
 angry and easily frustrated " , justifying that its items are repeated in other 
 questions .
the second question suggested to exclude was " i have lost 
 earnings " because its semantic equivalence with the item " i have had to 
 take time off work " .
stage vi : submission of documentation to the coordinating committee for appraisal of 
 the adaptation process the final stage in the adaptation process was the submission of all the reports to a 
 committee formed by the authors of the research and another portuguese speaking 
 professor . as related in the item above this committee decided to remove the 
 questions " i am irritable , angry and easily frustrated " and " i have 
 lost earnings " .
the brazil - mopds was applied in fifty patients with symptoms of orofacial pain who 
 consulted at the tmj and occlusion clinic of the prosthetic department of so 
 paulo university school of dentistry , brazil .
all patients were recruited before any 
 type of treatment , clinical consultation or other information about orofacial pain 
 was collected and all of approached patients agreed to participate .
initially they 
 were 75 but only 50 concluded the steps of the designed study ( figure 1 ) .
the brasil - mopds was administered twice by an interviewer ( 15 - 20 
 day interval ) and once by a second independent interviewer .
the brazilian version of 
 the short form oral health impact profile ( ohip-14 ) questionnaire and the visual 
 analogue scale ( vas ) were applied on the same day .
ohip-14 score were based on its seven dimensions ( physiological discomfort , pain , 
 physiologic inability , physical inability , function limitation , disability and 
 social inability ) and scored from 0 - 4 based on a likert scale : 0 - never , 1 - 
 rarely , 2 - sometimes , 3 - frequently and 4 - always .
this value was then multiplied 
 by the weight of each question to give a score ranging from 0 ( less oral health 
 impact on daily profile ) to 28 points ( more impact ) .
all participants have read and signed informed consent form . the use of human 
 subjects in this study has been reviewed and approved by university of so 
 paulo dentistry school ethics committee .
this study was conduced from august 1 , 2008 
 to march 1 , 2009 ) .
data were tabulated and analyzed in stata 10   and for all tests it were used confidence interval of 95% .
internal 
 consistency was examined by cronbach . in order to find the correlation 
 between each question and the overall outcome of the test , the spearman correlation 
 coefficient ( scc ) was performed , using data from the first interview ( main test ) . 

psychometric properties : reliability was estimated by assessing the internal 
 consistency ( indicated by cronbach  ) and reproducibility ( test - retest ) .
the 
 statistical value of cronbach  was also calculated for each excluded question 
 from the brazil - mopds as the objective of statistical investigation was to 
 numerically represent the interests of uniformity or trend in the responses within 
 each item of the questionnaire .
reliability was checked by the application of brazil - mopds on two occasions by the 
 same rater , called internal reliability .
external reliability was the comparison of 
 the answers obtained by the first and the second evaluator .
for these analysis 
 interclass correlation coefficient ( icc ) and bland - altman test   were used .
the samples were distributed by gender and age . most of the participants were women 
 ( 86% ) with the average age of 40.7 ( sd 14.03 ) years old ( table 1 ) .
the answers of the questionnaire obtained by the first rate ( first and second 
 interview ) and the second rate are described in table 2 .
the correlation between each question , the whole result and 
 cronbach  is shown in table 3 . answers distribution by the three interviews n = number of participants .
correlation between questions and whole brazil - mopds and cronbach 
  if the question were excluded pearson correlation , question - whole result .
reproducibility ( test - retest ) : interobserver correlation data obtained in 
 questionnaire administration indicated an excellent agreement with icc = 0.924 ( ci 
 0.46 - 0.98 ) ( figure 2 ) .
in order to evaluate 
 graphically the agreement or discrepancy between the sums of numerical responses 
 given by patients questioned on the same day by two different interviewers , the 
 results of applications of brazil - mopds were plotted in a bland - altman plot ( figure 3 ) . bland - altman plot with inter observer reproducibility .
this enabled us to recognize the magnitude of variation between the responses as well 
 as the existence of systematic bias between the two interviewers .
the value of the 
 arithmetic mean was equal to - 0.48 ( ci 1.08 - 0.12 ) , showing a strong correlation 
 .
data obtained in the intra - observer correlation in the administration of the 
 questionnaire , also showed an excellent agreement with icc = 0.982 ( ci 0.967 - 
 0.997 ) ( p < 0.001 ) ( figure 3 .
criterion validity was established by comparing the data of the scale with the 
 results of the ohip-14 , vas and the three brazil - mopds interviews ( table 4 ) .
the correlation between the scores of brazil - mopds and ohip-14 was high , r = 0.857 
 ( ci 0.765 - 0.915 ) ( p < 0.001 ) and the correlation of scores of brazil - mopds 
 with vas was also strong - r = 0.758 ( ci 0.615 - 0.852 ) ( p < 0.001 ) .
we have successfully adapted the mopds into the portuguese language . not only were we 
 able to translate it , but also validate and culturally adapt it .
previous 
 instruments have not been specifically designed to measure the impact associated 
 with orofacial pain .
orofacial pain has not only biological but also psychological and social effects on 
 patients .
psychosocial effects are 
 difficult to objectively measure and certainly deserve attention in the evaluation 
 of therapeutic measures for chronic orofacial pain .
in fact they may be the only 
 measures to assess patient improvement particularly where there is no underlying 
 pathology to explain reported symptoms [ 17 - 21 ] .
further , indicators of oral health related quality of life are often used to 
 complement clinical data in cross - sectional and longitudinal studies .
borges et al .   estimated the prevalence of dental and gingival pain and associated 
 factors among 16,126 young brazilians ( 15 - 19 years ) who participated in the 
 epidemiological survey of oral health ( 2002 - 2003 ) in brazil for six months . 
 through simple and multiple poisson regression
there was a high prevalence of dental 
 and gingival pain : 35.6% ( ci : 34.8 - 36.4 ) .
the increased prevalence of pain was 
 associated with female public school students , low income and education gap . 

adolescents with high levels of caries and dental calculus also reported a higher 
 prevalence of dental pain .
the successful translation and cross - cultural adaptation of the mopds , which had its development based on people 
 who had just this specific condition will therefore be extremely valuable to measure 
 the specific effects of orofacial pain in brazilian populations .
other questionnaires like gohai ( geriatric oral health assessment index , rdc / tmd , 
 ohip , mcgill pain questionnaire and oidp have been translated and validated for use 
 in brazilian researches [ 24 - 29 ] .
however , these instruments have not been 
 specifically designed to measure the impact associated with orofacial pain .
although some english terms do not have equivalent descriptors in portuguese , 
 trans - cultural adjustments proved to be a valid and efficient alternative to 
 overcome this difficulty , which can be confirmed in the application of the final 
 version of the questionnaire .
adaptation to local culture is essential for a correct 
 evaluation of the process of pain .
therefore the brazil - mopds was obtained from translation and cultural adaptation as 
 performed according to current and internationally accepted guidelines . 

it showed excellent reproducibility , validity and practicality application with high 
 cronbach 's  scores , and good correlation co - efficient .
the bland - altmann test , 
 associated with the icc was used for providing more information than the use of a 
 test alone .
one of the main advantages of this method , in which differences between 
 the scores of the first and second evaluation are plotted on the mean values 
 is to allow the recognition of both the amplitude of variation as to 
 the existence of systematic bias between the two interviews it is necessary at least 
 50 individuals for the use of this method .
however , our study was conducted on patients referred into a tertiary setting who may 
 represent the most severe and intractable cases of orofacial pain .
further research 
 is needed in establishing the validity of the brazil - mopds in population settings 
 and also its responsiveness as a measurement of treatment outcomes in clinical 
 trials of chronic orofacial pain .
we envisage that it will be an important tool for 
 such patients where improvement can not be assessed in terms of structural 
 improvement ( elimination of infection or removal of diseased tissue ) as there is no 
 underlying cause for reported symptoms .
rather , measurements of disability before 
 and after treatment may provide important information on treatment outcomes and 
 therefore influence further management of the patient .
the data showed that the process of translation and cross - cultural adaptation of 
 manchester orofacial pain disability scale was successful and that brazil orofacial 
 pain disability scale seems to be a valid and reliable instrument for describing 
 pain - related impact among patients with symptoms of orofacial pain .
the 
 study was funded by the author and school of dentistry of university of 
 so paulo , brazil .
vishal aggarwal is funded by a clinician scientist 
 award issued by the nihr - grant number cs/2008/08/001 .
the views expressed in 
 this publication are those of the author(s ) and not necessarily those of the 
 nhs , the national institute for health research or the department of health uk . 

vishal aggarwal also has a 
 substantive part - time appointment as a senior lecturer in academic general 
 dental practice at queen mary 's university london , uk .
no external funding , apart from the support of the authors ' institution , was 
 available for this study .
 abstractobjectivesthe purpose of the present study was to translate and perform a 
 cross - cultural adaptation of manchester orofacial pain disability scale to 
 the portuguese language.material and methodsa synthesis of two independent translations done by bilingual translators 
 whose mother tongue was the portuguese language began the process of 
 translation . from the synthesis of the translated version and totally blind 
 to the original version , two different non - native english language teachers 
 without dental knowledge translated the questionnaire back to english . 
 the 
 pre - final version was done by an expert committee : the researchers , two 
 other non - native english language teachers and one native english language 
 speaker . 
 the new questionnaire was then piloted among 8 patients from the 
 target setting that were interviewed to probe it on their perceived meaning 
 of each question . 
 the manchester orofacial pain disability scale ( mopds ) 
 thus translated was called brasil - mopds and was validated in 50 patients 
 with orofacial pain from tmj and occlusion clinic ambulatory of so 
 paulo university school of dentistry . 
 the brasil - mopds was administered 
 twice by an interviewer ( 15 - 20 day interval ) and once by a second 
 independent interviewer . 
 the brazilian version of the short form oral health 
 impact profile ( ohip-14 ) questionnaire and the visual analogue pain scale 
 ( vas ) were applied on the same day.resultsinternal consistency ( cronbach 's  = 0.9 ) , inter - observer ( icc = 0.92 ) 
 and intra - observer ( icc = 0.98 ) correlations presented high scores . 
 validity 
 of brasil - mopds compared to ohip-14 ( r = 0.85 ) and vas ( r = 0.75 ) shown high 
 correlations.conclusionsbrasil-mopds was successfully translated and adapted to be applied to 
 brazilian patients , with satisfactory internal and external reliability . 
INTRODUCTION
MATERIAL AND METHODS
RESULTS
DISCUSSION
CONCLUSIONS
ACKNOWLEDGMENTS AND DISCLOSURE STATEMENTS