the term of the  global budget system  started to appear in medical literature since 50 years ago . the global budget system indicates a payment method  by which hospitals are allotted a specific amount of money and are then free to distribute the funds according to their individual priorities . 
although initial purposes of the system were to provide hospitals and clinics a  greater flexibility in the distribution of funds received  and  a financial incentive to operate as efficiently as possible ,  cost reduction to health care services by  putting hospitals at operating risk  has become an expected effect . by year 2014 , this payment system has been implemented on different scopes of health care services in countries such as canada , germany , switzerland , the united states of america ( usa ) , and taiwan . to the best of our knowledge ,
the earliest inclusion of dental services in the global budget system commenced in germany and was followed by taiwan .
the global budget system applied to dental care services in taiwan was planned and monitored by the ministry of health and welfare ( mohw ) . to implement the system , a budget was allocated to the six regional branches of the national health insurance ( nhi ) administration , including taipei region , northern taiwan , middle taiwan , southern taiwan , kaohsiung - pingtung region , and eastern taiwan .
an expenditure cap was decided according to the expenditure of dental services in the previous year .
although a limited annual increase of the expenditure was included in the cap , the reimbursement value of each item would become lower when the amount of dental services used was larger than a previously planned target .
the expected outcomes of the global budget system in taiwan included an increase in the quantity of preventive dental care and a well - controlled expenditure cap under peer pressure within dental associations .
the government has been satisfied with the effect of the global budget system and expanded the implementation to the scope of traditional chinese medicine and modern medicine years later .
however , dental practitioners were concerned with payment inequity in relation to market competition and disparities of socioeconomic status .
health care provider supply and competition in the health care market have a reciprocal influence for each other .
dentist over - supply is becoming an issue of concern in developed countries such as canada , sweden , united kingdom and the usa , as well as newly industrialized countries including south africa and india . to boost the work capacity of over - supplied dental manpower
, some researchers suggested that the government should offer dental insurance to induce demand for dental services .
a previous study reported that new dental graduates did not follow traditional models of dentist distribution when entering a service market .
indeed , there was no relationship between young dentists selection of practice location and the population size of an area .
the density of dentists in an area was enhanced by factors such as the opportunity of dental training programs , residents per capita income , health care expenditures per resident , the proportion of minority in the community , and the insurance penetration rate .
the situation in taiwan was different 50 years ago when baker and perlman reported a low reputation , mild income , and insufficient manpower of dental practices . at that time , a low registration rate at dental schools in taiwan was also identified . in the early 70 's ,
only three - quarters of dental graduates practiced in private clinics , and 12.1% of them left taiwan for purposes such as advanced studies or immigration .
dynamics of the dental manpower in taiwan depended on the size of the community population although the density was as low as 6.6 dentists per 100,000 population then .
this was different from young american dentists relocation that was motivated by a variety of factors .
an uneven distribution of dentists in taiwan has been reported , and approximately 30% of taiwanese towns have never attracted a qualified dentist before 1990 . by the end of the 20 century , the highest and lowest density of dentists was reported in taipei city ( 67.5 dentists/100,000 population ) and penghu county ( 5.2 dentists/100,000 population ) , respectively .
compared to the capital of the usa which had almost 100 dentists/100,000 population at a similar survey time , the capital of taiwan , taipei city , was not severely overwhelmed by over - supply of dental manpower , not to mention rural and remote areas such as penghu county . when searching the medline literature database with a combination of keywords including  dentist , 
 dental practice ,   dental surgeon  or  dental manpower  and  global budget ,  only four papers were identified . excluding a paper reporting pharmaceutical expenditures but not utilization of dental care services , the remaining studies reported controversial outcomes .
suggested that the implementation of the global budget system failed to improve the distribution of dental manpower because of a declined utilization of dental care services . on the contrary , two studies demonstrated an increase in utilization following a more intense competition of dental care market resulting from the implementation of the global budget system .
although the nhi system in taiwan has established an international reputation for its effectiveness , dynamics of dental manpower in relation to the global budget system remained under - investigated .
therefore , this study aimed to investigate into dentistsupply and practice patterns and to assess structural changes of dental manpower following the implementation of the global budget system in taiwan .
an additional interest of this study was to report utilization of dental care services in relation to the application of the payment scheme .
the hypothesis of the study was that the distribution of dental manpower was influenced by socioeconomic factors and the implementation of the global budget system .
this study compared the difference in dental practice patterns with pre- and post - innovation of the global budget system in taiwan .
cross - sectional data were applied to assess distribution of dental manpower among practice locations and longitudinal data were used to analyze transition of practice patterns . because nationwide health care data were unattainable , claim data from the bureau of national health insurance ( bnhi ) from 1995 to 1998 were used .
the data used included frequency of dental visits , diagnoses , treatments and the total fee charged .
socioeconomic data collected from the annual report of the ministry of internal affair ( moi ) , including levels of education , family revenue and health expenditures , were divided into six regions according to regional branches of the bnhi .
demographic data received from the moi were composed of the density and growth rate of the population , as well as the percentages of elderly and young populations .
the elderly and young populations were defined as those residents who were 65-years - or older , and those children who were 14-years - or younger , respectively .
dental manpower data such as registrations for practice locations were received from the mohw . to take the effect of market competition on dental manpower into account ,
the herfindahl - hirschman index ( hhi ) was applied as estimate the level of competition within a domestic dental market .
it was formulated as : where x was the number of dental hospitals / clinics located in a municipality ( a city or county ) , ni was the number of dentists registered at a hospital / clinic of the municipality , and n was the total number of dentists registered in a municipality .
an hhi value closer to 1 indicates a market closer to a monopoly , while an hhi approaching to 0 represents a highly competitive market .
a dentist move - in rate was defined as the quotient having the move - in number divided by the total number of dentists in a municipality .
similarly , a dentist move - out rate was calculated with the same division methods .
data entry and statistical analysis were carried out with ibm spss statistics ( version 19.0 , ibm corporation , somers , ny , usa ) .
a multivariate linear regression method with a step - wise approach was used to assess the individual contribution of socioeconomic and demographic factors in relation to dependent variables of dental manpower .
the dependent variables included the number of dentists per 100,000 population , dentists move - out rate and dentists move - in rate . dental claims from july 1997 to december 1998 were analyzed as the global budget system has been implemented in taiwan since july 1998 .
eight categories of treatment carried out as outpatient dental care services and reimbursed under the global budget system were included in the study .
these included radiographic examinations , endodontic treatments , amalgam restorations , tooth - colored restorations ( composite resin and/or glass ionomer cement restorations ) , periodontal surgeries , nonsurgical periodontal treatments , oral and maxillofacial surgeries , and pulpotomies for deciduous teeth .
utilization of dental services in each treatment category before and after the implementation of the global budget system was examined with a chi - square method .
during the 4 year study , the average number of dentists in a municipality of taiwan ranged from 9.6 to 70.5 dentists/100,000 population .
taipei city and chiayi county ( an agricultural county located in southern taiwan ) reported the highest and lowest density of dentists , respectively .
the difference in the density between taipei city and chiayi county reduced from 8.4 times in 1995 to 6.7 times in 1998 . on the other hand ,
the highest move - out rate was seen in penghu county , while the lowest was identified in tainan county , which was another agricultural county located in southern taiwan .
the move - in rate among dentists ranged from 0.084 to 0.170 , with the lowest and highest value in taipei city and penghu county , respectively .
of further note , the range of the hhi calculated was from 0.002 to 0.117 .
taipei county ( a metropolis surrounding taipei city ; with the name changed to new taipei city in year 2010 ) and penghu county had the lowest and highest values of hhi , respectively .
a municipality that reported a higher percentage of tertiary educated population ( t = 3.718 , p < 0.001 ) , that had a higher per capita income ( t = 6.172 , p < 0.001 ) , that showed a higher population density ( t = 6.172 , p < 0.001 ) , that displayed a lower percentage of elderly population ( t = 2.506 , p = 0.014 ) , or that was located at middle taiwan ( t = 4.234 , p <
0.001 ) was more likely to have a higher number of dentists per 100,000 population [ table 1 ] .
implementation of the global budget system , per capita health care expenditure , the percentage of young population , the hhi value , geographic locations other than middle taiwan , and the years were not related to the density of dentists ( p  0.097 ) .
individual contribution of socioeconomic and demographic factors to dentists number per 100,000 population in addition , a municipality that reported a higher hhi value ( t = 2.880 , p = 0.005 ) was more likely to show a higher move - out rate among dentists [ table 2 ] .
the rate was lower after the implementation of the global budget system ( t = 2.436 , p = 0.018 ) and in southern taiwan ( t = -2.949 , p = 0.004 ) .
other factors were not associated with dentists move - out rate ( p  0.258 ) .
individual contribution of socioeconomic and demographic factors to dentists move - out rate moreover , a municipality that had a higher percentage of elderly population ( t = 3.628 , p < 0.001 ) , that reported a lower percentage of young population ( t = 2.138 , p = 0.035 ) , or that showed a higher rate of population growth ( t = 4.412 , p <
0.001 ) was more likely to display a higher move - in rate among dentists [ table 3 ] .
year 1996 also showed a higher move - in rate compared to year 1995 ( t = 3.385 , p = 0.001 ) .
none of other factors was in connection with the rate ( p  0.243 ) .
individual contribution of socioeconomic and demographic factors to dentists move - in rate on the other hand , the number of dental management items claimed to the nhi in the years 1997 and 1998 was 11,190,099 and 11,310,202 , respectively [ table 4 ] .
the percentage of amalgam restorations reduced from 19.82% in the year 1997 to 17.94% in the year 1998 , while the percentage of tooth - colored material restorations , increased from 25.46% to 28.79% .
other categories of dental management items showed a negligible range of changes in the percentages of claims .
figures 1 and 2 show a decreasing trend in the percentage of amalgam restorations among total claims , in relation to an increasing trend in tooth - colored material restorations .
all other management items displayed a negligible range of changes according to the monthly data .
percentages of utilisation of dental services number of amalgam and tooth - coloured material restorations claimed to national health insurance .
this is the first study to suggest a stabilizing effect of the global budget system on dynamics of dental manpower .
however , this study did not find a relationship between the global budget system and the number of dentists per 100,000 population as well as dentists move - in rate .
thus , a lower move - out rate reported by this study indicated that the implementation of the payment system contributed to a more stable market .
this resembled a previous study demonstrating that distribution of dentists was not improved by application of the global budget system .
restricted by the predetermined expenditure cap ,  any increase in the service capacity would result in a lower reimbursement value for all items claimed by dentists in a region .
thus , local dental associations could have raised the threshold for entry , such as a high registration fee , to deter new dentists from moving into the market .
this would consequently prevent existing dentists from moving out of a region since the cost of moving into another region could be too high .
nevertheless , new dental graduates could only move in but not move out a market .
this might explain the reason why only the move - out rate was reduced following the implementation of the global budget system .
this study has also reported for the 1 time a positive relationship between hhi and dentists move - out rate . according to literature ,
a higher hhi value indicated a market closer to a monopoly . because data of hhi and dentists move out rate were collected from the corresponding years , it became difficult to interpret a causal relationship between these two variables .
a possibility was that a higher move - out rate reduced the number of dentists in a municipality and consequently led the market toward a status of a monopoly .
on the other hand , a monopoly - like market could indicate a municipality that had fewer dentists .
these municipalities were generally agricultural or island countries characterized by a smaller population size and lower per capita income . furthermore
, an earlier study reported that a higher hhi value contributed to a lower amount of dental care expenditure per person .
thus , dentists could have opted to move out from a high hhi municipality due to a less profitable practicing location and the less preferred living environment .
since both situations could result in a positive relationship between hhi and dentists move - out rate , further investigations are indicated .
in addition , this study demonstrated a positive relationship between the density of dentists and average socioeconomic status of a municipality .
we found that a higher number of dentists per 100,000 population was accompanied by a higher percentage of the tertiary educated population and a higher per capita income of a municipality .
this agreed with an earlier study reporting that more dentists opted to practice in areas of high socioeconomic status .
relevant reasons for the concentration of dentists in high socioeconomic areas included children 's education , family reasons , financial reasons , and professional development . as a higher number of dentists with more years experience opted to practice in wealthier areas ,
new dental graduates could have consequently moved into low socioeconomic areas such as municipalities showing a higher percentage of the elderly population .
this was also confirmed by our study , since a lower density of dentists and a higher move - in rate among dentists were seen in municipalities with a higher percentage of the elderly population . even though young dental graduates showed a higher likelihood to practice dentistry in disadvantaged areas compared to experienced dentists , years later they may still leave these areas for municipalities with a higher average socioeconomic status .
although the implementation of the global budget system had a stabilizing effect on dynamics of dental manpower , establishment of professional development programs and an attractive reimbursement value at underserved areas are indicated . on the other hand , this study has identified a complementary relationship between amalgam and tooth - colored material restorations in the aspect of utilization of dental services . an upward trend of utilization of tooth - colored material restorations
this connection could have resulted from a higher reimbursement value of composite resin over amalgam restorations . nevertheless , the influence from the implementation of the global budget system was unclear , as the complementary effect has been seen since a year prior to the commencement of the payment system . of further note ,
a previous study has reported a transition of dental materials used from amalgam toward tooth - colored materials due to patients esthetic considerations . despite the fact that health risks from dental amalgam restorations remained controversial ,
amalgam has been permanently replaced by other materials for restorative dentistry in countries such as sweden and norway .
thus , the international trend could also have contributed to the complementary relationship between amalgam and tooth - colored materials in taiwan .
this study has demonstrated a stabilizing effect of the global budget system on dynamics of dental manpower in taiwan .
a positive relationship between hhi and dentists move - out rate has been reported by this study .
the relationship between the socioeconomic status of a municipality and the density of dentists has also been confirmed .
in addition , reduced utilization of amalgam restorations was accompanied by increased utilization of tooth - colored material restorations .
the authors of this manuscript declare that they have no conflicts of interest , real or perceived , financial or non - financial in this article .
the authors of this manuscript declare that they have no conflicts of interest , real or perceived , financial or non - financial in this article .
 background : this study aimed to investigate dentists supply and practice patterns following the implementation of the global budget system in taiwan.materials and methods : data of reimbursement claims , municipal socioeconomic status and dental manpower were collected from the national health insurance administration , the ministry of internal affair , and the ministry of health and welfare , respectively . a multivariate linear regression method was used for data analysis.results:a municipality that reported a higher percentage of tertiary educated population ( t = 3.718 , p < 0.001 ) , a higher per capita income ( t = 6.172 , p < 0.001 ) , a higher population density ( t = 6.172 , p < 0.001 ) , or a lower percentage of elderly population ( t = 2.506 , p = 0.014 ) was more likely to have a higher number of dentists per 100,000 population . a municipality that reported a higher herfindahl - hirschman index ( hhi ) value ( t = 2.880 , p = 0.005 ) was more likely to show a higher move - out rate among dentists . 
 the rate was lower after the implementation of the global budget system ( t = 2.436 , p = 0.018 ) . 
 a municipality that had a higher percentage of elderly population ( t = 3.628 , p < 0.001 ) , a lower percentage of young population ( t = 2.138 , p = 0.035 ) , or a higher rate of population growth ( t = 4.412 , p < 0.001 ) was more likely to display a higher move - in rate among dentists . 
 the percentage of amalgam restorations in total claims reduced from 19.82% to 17.94% , while the percentage of tooth - colored material restorations increased from 25.46% to 28.79%.conclusion : this study has demonstrated a stabilizing effect of the global budget system on dynamics of dental manpower in taiwan . a relationship between hhi and dentists move - out rate has been found . 
 the relationship between municipal socioeconomic status and the density of dentists has also been confirmed . 
 in addition , reduced utilization of amalgam restorations was accompanied by increased utilization of tooth - colored material restorations . 
 further investigations are indicated . 
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
CONCLUSION
Financial support and sponsorship
Conflicts of interest