demineralization or white spot lesion ( wsl ) development in the enamel in association with orthodontic treatment with fixed appliances remains a well - known clinical problem for dental specialists .
various methods how to prevent its formation are discussed in the literature , but still it is not determined which one is the most effective .
wsls can become visible around fixed appliances within one month of bracket placement , although the formation of regular caries usually takes at least 6 months ( figure 1 ) .
individuals with malocclusion usually have difficulty in performing proper oral hygiene because of many retention sites .
in addition , bonding attachments to teeth make conventional oral hygiene more difficult , and can prolong plaque accumulation on tooth surfaces .
wsls mainly appear on buccal surfaces of the maxillary teeth in the following order : lateral incisors , canines , premolars , and central incisors . according to the literature the prevalence of wsls after orthodontic treatment
is about 50% and its prevention is the purpose of every orthodontist [ 7 - 12 ] . 

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  primary prevention of wsls can be done adjacent to fixed appliances and secondary prevention ( treatment ) is done when the braces are removed .
wsls can be very difficult or sometimes even impossible to improve when fixed appliances are removed , and complete resolution of the lesions can rarely be achieved , it influences aesthetics and the patients satisfaction with their smile .
moreover , untreated wsls can lead to the formation of dental caries and restorative treatment .
saliva can re - mineralize wsls to some degree , although this process is faster during the first few months , and later it becomes slower .
thus an early prevention of the wsls is one of the goals of modern orthodontic treatment .
natural remineralization through saliva involving mineral gain in the surface layer of wsls has little improvement on the aesthetics and structural properties in the deeper lesions .
therefore , it is necessary to apply remineralizing agents to repair the deeper parts of wsls for better aesthetic results . the use of various fluoride and casein phosphopeptide - amorphous calcium phosphate ( cpp - acp ) derivatives , such as high - fluoride toothpaste , varnish , mouth rinse , gel or topical cream used for remineralization was reported in literature [ 18 - 23 ] . in his study
willmot   concluded that cpp - acp was capable of absorbing through the enamel surface and could influence the carious process .
cpp - acp is a delivering system that allows freely available calcium and phosphate ions to attach to enamel and reform into calcium phosphate crystals . in the clinical studies
it was found that various methods are used for prevention of wsls , but discussion which is the most effective method of the prevention is still proceeding .
the aim of the systematic literature review is to update the evidence for the prevention of wsls , using materials containing fluoride and/or casein phosphopeptide - amorphous calcium phosphate during and after treatment with fixed orthodontic appliances .
protocol and registration this systematic review was conducted following the prisma ( preferred reporting items for systematic reviews and meta - analyses ) statement .
evaluating the results of scientific researches hypothesis arises if it is possible to prevent development of wsls using materials containing fluoride and/or casein phosphopeptide - amorphous calcium phosphate during and after treatment with fixed orthodontic appliances .
the following focus question was developed according to the population , intervention , comparison , and outcome ( picos ) study design ( table 1 ) .
the review included all human prospective and retrospective follow - up studies and clinical trials , cohort studies , case - control studies , and case series studies published between january 2008 and february 2016 , on development and prevention of wsls , using materials containing fluoride and/or cpp - acp during and after treatment with fixed orthodontic appliances .
the literature search was performed in pubmed ( national library of medicine , ncbi ) , embase , sciencedirect and cochrane databases .
the references of each relevant study were screened to discover additional relevant publications and to improve the sensitivity of the search .
the search was conducted using the following keywords : ( casein phosphopeptide - amorphous calcium phosphate nanocomplex or calcium phosphate or casein phosphopeptide - amorphous or cpp - acp or casein phosphopeptide amorphous calcium phosphate ) and ( orthodontic brackets or fixed appliances or dental debonding or bonding ) and ( fluoride or fluoride varnish or fluoride rinse or fluoride toothpaste ) and ( orthodontics or orthodontic treatment or orthodontic treatment complications ) and ( white spot lesion or dental caries or demineralization or decalcification or enamel defects ) .
the choice of keywords was intended to be broad , in order to collect as much relevant data as possible without relying on electronic means alone to refine the search results .
the resulting articles were independently subjected to clear inclusion and exclusion criteria by two reviewers as follows .
reviewers compared decisions and resolved differences through discussion , consulting a third party when consensus could not be reached .
inclusion and exclusion criteria inclusion criteria for studies were :   patients of any age undergoing orthodontic treatment with fixed appliances ; preventive treatment of wsls with fluoride - containing product and/or casein derivatives .
exclusion criteria for studies were : subjects underwent any non - remineralizing therapy ( bleaching or restoration ) during trial .
sequential search strategy following the initial literature search , all article titles were screened to eliminate irrelevant publications , review articles , case reports , and animal studies .
next , studies were excluded based on data obtained from screening the abstracts . the final stage of screening involved reading the full texts to confirm each study s eligibility , based on the inclusion and exclusion criteria .
the data were independently extracted from studies in the form of variables , according to the aims and themes of the present review , as listed onwards .
data were collected from the included articles and arranged in the following fields : participants , examination methods , preventive treatment methods , study design , main findings .
assessment of methodological quality the risk of bias assessment of the included trials was undertaken independently and in duplicate by at least two review authors as part of the data extraction process .
this was conducted using the recommended approach for assessing risk of bias in studies included in cochrane reviews .
relevant data of interest on the previously stated variables were collected and organised into table .
the initial search identified a total of 326 references . following the screening of the article titles ,
independent screening of the abstracts resulted in the selection of 42 publications for possible inclusion .
finally , 12 articles that met the predefined criteria were included in the systematic review ( figure 2 ) . 

prisma flow diagram illustrating the literature search protocol . 
  the reasons for excluding studies after full - text assessment were as follows : non - human studies ( n = 1 ) , in vitro studies ( n = 6 ) , trials with patients who underwent any non - remineralizing therapy ( bleaching or restoration ) during trial ( n = 1 ) , case reports and review studies ( n = 9 ) , could not be excluded before careful reading ( n = 13 ) . the quality assessment of the included studies revealed an unknown risk of bias ( for one or more key domains ) for the majority of the included studies [ 5,8,19,20,27 - 34 ] , one study   was classified as low risk ( of bias for all key domains ) ( table 2 ) .
study characteristics the included studies were compared regarding to the number of the participants , examination methods , preventive treatment methods , study design , main findings .
the mentioned 12 articles were published between january 2008 and february 2016 , two studies were performed exclusively on topical fluoride , two studies were performed on high - fluoride toothpaste , four studies were performed on casein derivate , there were one mixed study ( fluoride vs. casein vs. oral hygiene ) and one mixed study ( fluoride vs. casein vs. microabrasion ) , also oral hygiene study and study performed on fluoridated chewing sticks ( miswaks ) .
no meta - analysis could be performed due to the heterogeneity in the study designs and treatment modalities .
influence of materials containing fluoride and/or cpp - acp on wsls multiple preventive agents had been tested over years to evaluate their effectiveness in prevention and treatment of wsls associated with orthodontic treatment with fixed appliances .
materials containing fluoride and/or casein phosphopeptide - amorphous calcium phosphate have been proven to be the most effective in fighting demineralization .
number of patients , examination methods , preventive treatment methods , study design , main findings ( statistically significant ) were used to determine which material is more effective in treatment and prevention of wsls ( table 3 ) . 

clinical studies evaluating the effectiveness of fluoride and casein supplements use in vivo 
  four clinical studies   reported no better effect of products containing fluoride ( fluoride varnish , fluoride toothpaste ) on wsls than normal home care for improving the appearance of wsls .
4 of 12 studies showed significantly better results in wsls appearance when using materials containing fluoride .
the use of cpp - acp was reported to be more beneficial than fluoride rinse for postorthodontic remineralization .
four clinical studies   reported topical treatment with a cpp - acp agent to significantly reduce are of wsls and help in prevention of the development of wsls .
two of 12 studies found no clinical advantage for use of the topical treatment with a cpp - acp agent in improvement of the appearance of wsls . however , 9 of 12 studies proved treatment using materials containing fluoride and/or cpp - acp to be beneficial for managing and preventing wsls .
prevention of demineralization during orthodontic treatment is one of the greatest challenges faced by clinicians despite modern advances in caries prevention . evaluating short duration of time during which wsls can develop and become irreversible ,
early diagnosis is considerably important , as modern dentistry is focused on a preventive approach instead of invasive restorations of carious defects .
the individual oral hygiene status of orthodontic patients must be accurately followed especially in the first months of orthodontic treatment , in order to prevent wsls development and its complications .
the modern methods for the evaluation of wsls are the following : the optical caries monitor , quantitative laser and light - induced fluorescence ( qlf ) , digital imaging with fiber - optic transillumination , and computer analysis of digital photographs .
the well - accepted and most popular methods for wsls evaluation are digital intraoral photography and qlf .
most relevant articles from the literature review used proportional rather than absolute measurements of luminance or size .
other studies used a combined scoring system based on the surface area and the severity of the opacity .
a number of scientific studies were performed over the last eight years in order to evaluate the effectiveness of the various remineralization methods , but data of these clinical researches were controversial . in some clinical studies , it was found that high - concentration fluoride varnish is significantly effective in reducing wsls .
results of the experimental study , evaluating the effect of fluoride varnish , showed that high - concentration fluoride varnish reduces 40% of wsls during orthodontic treatment .
controlled clinical trial stated that fluoride varnish was effective during the first three months after bonding and six months after debonding . in the other study the effectiveness of fluoridated chewing sticks in reducing wsls in post - orthodontic patients
some scientist reported that the usage of highly fluoridated tooth paste and fluoride varnish during orthodontic treatment are significantly beneficial as a preventive material in the reducing wsls around braces . while huang et al .   and bailey et al .  
discussed warnings against the use of high concentrations of fluoride because the superficial layer might prevent calcium and phosphate from penetrating to the deeper layers of the enamel , thus inhibiting deeper remineralization and limiting the cosmetic improvement of the wsls .
richter et al .   concluded that fluoride varnish or fluoride mouth rinse was not effective , no significant association between the decrease in number of new lesions and application of materials containing fluoride was found .
contradictory results were reported in some clinical studies , no significant difference between the use of fluoride varnish , mi paste or the usual oral hygiene using 1100 ppm fluoride toothpaste , a toothbrush , and dental floss was found . in these clinical trials
size of the study sample , duration of the fixed orthodontic treatment , period , when preventive remineralization procedures are used , are variable . the heterogeneous methodology was applied in order to evaluate the formation of wsls .
therefore it influences the outcomes of the studies and clarifies the contradictory results of the effectiveness of the preventive procedures . in recent
scientific researches the use of mi paste during orthodontic treatment was overlooked and its effect in remineralization of wsls was confirmed .
although in some studies there was reported no significant usefulness of mi paste or mi paste plus , some improvement in wsls was found .
compared the effectiveness of mi paste on wsls after orthodontic treatment with control group and stated that the size of the lesion area has not changed significantly over time or between the groups . the other factor that can influence
the reduction of wsls is topical fluoride and cpp - acp applications , which effectiveness was compared in several studies . for the last eight years clinical in vivo studies
have been evaluating the effectiveness of fluoride and cpp - acp therapy during and after orthodontic treatment with fixed appliances .
some studies proved that high - fluoride derivates significantly reduces wsls after 6 weeks to 6 months , while their opponent failed to demonstrate an additional effect of fluoride varnish compared with normal home care over an 8 week period .
the conclusions about the effect of cpp - acp derivates are debatable , bailey et al .   and brchner et al .  
claimed that casein supplements are effective after 4 and 12 weeks , the opponents huang et al .  
proved in their trials that cpp - acp is as effective as normal oral care over a 8 to 12 weeks period . according to present study ,
the most important factors for preventing decalcification and formation of wsls were a good oral hygiene regimen and a modifying diet with low carbohydrate intake .
other additional methods such as fluoride varnish , rinse , chewing sticks , or cpp - acp supplements did not totally prevent the formation of wsls , but their incidence could be significantly reduced .
clinical in vivo studies investigating wsls prevention and treatment are still very rare . some clinical studies were not comparable due to small sample sizes , various inclusion criteria , unreliable statistical analyses that failed to account for clustering effects and use of unproven assessment methods without relating them to more accepted techniques ( only visual examination ) .
the lack of high - quality clinical studies makes it difficult to determine whether various agents are effective and which of them are more effective than others .
concerns have been raised against the use of highly concentrated fluoride to assist remineralization since it may lead to unsightly staining .
though , there were no recent trials available that could either confirm or reject this important question .
evaluating the results of the present study , we can claim that the usage of fluoride and casein supplements during and after fixed orthodontic treatment is significantly effective in the reduction of demineralization spots , however the use of cpp - acp can be more beneficial than fluoride rinse for postorthodontic remineralization .
it is also important to analyse if there are any other predictors for the degree of wsls improvement - such as time since the removal of the appliances , or the severity of the lesions .
further clinical studies evaluating the effectiveness of the methods for preventing and treatment of wsls must be performed in order to get more clinically significant evidence of these measurements and standardized procedures have to be presented .
early detection of white spot lesions during orthodontic treatment is of great importance as it would allow implementing preventive measures to control the demineralization process before lesions progress .
the systemic review of studies performed over the last years has showed that the usage of fluoride and casein supplements in ameliorating white spot lesions during and after fixed orthodontic treatment is significantly effective in the reduction of demineralization spots .
clinical evidence showed that treatment using materials containing fluoride and/or casein phosphopeptide - amorphous calcium phosphate is beneficial for managing and preventing white spot lesions . for higher - risk patients additional measures such as high - concentrated fluoride varnish or casein derivate
the use of casein phosphopeptide - amorphous calcium phosphate can be more beneficial than fluoride rinse for postorthodontic remineralization .
it is suggested to use casein phosphopeptide - amorphous calcium phosphate tooth mousse twice in addition to high fluoride toothpaste for 6 months to succeed in treating postorthodontic demineralized white spot lesions .
future clinical studies need to focus on the preventive measures in reducing the prevalence of white spot lesions .
the authors declare that there are no financial or other conflicts of interest related to this publication .
 abstractobjectivesthe aim of the systematic literature review is to update the evidence for the prevention of white spot lesions , using materials containing fluoride and/or casein phosphopeptide - amorphous calcium phosphate during and after treatment with fixed orthodontic appliances.material and methodsinformation search for controlled studies on humans published between january 2008 and february 2016 was performed in pubmed , sciencedirect , embase , the cochrane library . 
 inclusion criteria were : the english language , study on humans , patients undergoing orthodontic treatment with fixed appliances , randomized or quasi - randomized controlled clinical studies fluoride - containing product or casein derivates used throughout the appliance therapy or straightaway after debonding.results326 articles were reviewed ( embase 141 , pubmed 129 , sciencedirect 41 , cochrane 15 ) . 
 twelve clinical studies fulfilled all inclusion criteria . 
 use of fluoridated toothpaste had a remineralizing effect on white spot lesions ( wsls ) ( p < 0.05 ) ; fluoride varnish and casein supplements were effective in prevention and early treatment of wsls ( p < 0.05).conclusionsearly detection of white spot lesions during orthodontic treatment would allow implementing preventive measures to control the demineralization process before lesions progress . 
 the systemic review has showed that the usage of fluoride and casein supplements in ameliorating white spot lesions during and after fixed orthodontic treatment is significantly effective . 
 however the use of casein phosphopeptide - amorphous calcium phosphate can be more beneficial than fluoride rinse in the reduction of demineralization spots . 
INTRODUCTION
MATERIAL AND METHODS
RESULTS
DISCUSSION
CONCLUSIONS
ACKNOWLEDGMENTS AND DISCLOSURE STATEMENTS