conventional cavity preparation and carious tissue removal are based on black 's principle of extension for prevention . this principle requires removing healthy tooth structure which is very destructive and leads to excessive tissue loss . in recent years conservative cavity preparation , which includes handpieces and burs , leads to the undesirable removal of healthy tooth structure . due to this excessive loss of sound tissue , efforts have focused on new techniques [ 1 , 2 ] .   over the last few years , new techniques and procedures for hard tissue removal were developed as alternatives to the conventional mechanical procedure . alternative carious dentin removal techniques have been proposed , including hand excavation , air - abrasion , air - polishing , ultrasonication , sonoabrasion , lasers , and chemomechanical methods [ 4 , 5 ] ( table 1 ) . the vector system is a new method combining both ultrasonic effects and microabrasive action of quartz crystal suspension . this method uses specially shaped metal tools for use with an abrasive slurry of silicon carbide ( vector fluid abrasive , grain size 4050  mm ) for micro - invasive preparation countouring and finishing of the tooth substance and nonmetal restorations . heat induction is almost eliminated so that only a small amount of liquid is needed . as a result the conditions of work during the preparation of carious lesions in teeth remain unchanged . the manufacturer suggests that the vector removes biofilm , plaque , calculus , and endotoxins . the resonating ring of the vector system converts the ultrasonic dynamics of 25  khz in a similar way to a hula - hoop . if it is pressed into the horizontal position it moves vertically with 90 degrees deflection . this allows a linear movement of the instruments parallel to the tooth surface and an adhering film of water or particle suspension . the ultrasound 's energy is thereby indirectly coupled onto the tissues to be treated . in contrast to diamond instruments , in the vector system the energy is transmitted indirectly via the silicon carbide particles ( average grain size approximately is 50  m ) carried in the water . preparation with the vector system is therefore carried out without exposure to high temperatures . therefore , the purpose of this study was to evaluate the vector system in comparison to the conventional air - motor technique . four extracted primary teeth without restorations and with similar fissure carious lesions , and four permanent teeth extracted for orthodontic reasons were used . class i cavities were prepared , provided that the cavity depth remained within the dentin limits . two primary and two permanent teeth were treated with an aerotor , and in the other group teeth had their carious lesions removed and cavity preparation was done with the vector system ( duerr dental , bietigheim - bissingen , germany ) . cavity preparation was done according to   manufacturer 's instructions with a special diamond bur with 1.8  mm of diameter . during cavity preparation , the prepared cavities were kept in ultrasounded solution for 30 minutes to eliminate dust and other tooth particules . according to electron microscopy instructions , specimens were coated with gold ( 150 seconds ) with the snonputter technique ( polaron sputter coater ) for electron microscopy images . prepared cavities were evaluated under a scanning electron microscopy ( jeol jsm-5600 , sem ) and dentine and enamel surface roughness and efficiency of carious tissue removal were studied . cavity preparation times with the vector system and the aerotor are shown in table 2 . the time required for cavity preparation using the vector system was much longer than the aerotor treatment . there were bigger and deeper cracks and fractures on the floor of the cavities prepared with the aerotor in comparison to the vector system . in cavities which were prepared with the vector system , cavity bordes which were prepared with the vector system were also as smoother ( figures 1(a)-1(b ) , figures 2(a)-2(b ) ) .   in the dentine surface , typically , these surfaces have previously been described as scaly or flaky , or as an irregular surface . smear layer was less evident at the cavities prepared with the vector system . while in cavities prepared with the vector system open tubule orifices could be observed , at cavities prepared with the aerotor it was observed that most of the tubule orifices were obstructed with a smear layer . also , the dentin surface of the cavity floor was smoother in cavities prepared with the vector system in comparison to the aerotor ( figures 3(a)-3(b ) , figures 4(a)-4(b ) ) . although cavity surfaces seem relatively smooth at 250 magnification , rough cavity surfaces with irregular particules were seen at the higher magnifications ( 500 , 1000 ) . more smear layer was seen in cavities prepared with the vector system than those prepared with the aerator . at vector system cavities , indented structure of dentin tubuluses particules were seen as to be nailed to the smooth dentin surface in the cavities prepared with the vector system . but tubules were observed as obstructed with debris , poor quality , and pointed surface view ( figures 5(a)-5(b ) , figures 6(a)-6(b ) ) . enamel lines were streamlined in both the aerotor and vector system ( figures 7(a)-7(b ) , figures 8(a)-8(b ) ) . this pilot study determined that it is possible to remove carious tissue and perform cavity preparation with the vector system . according to this preliminary evaluation of surface quality , a cavity prepared with the vector treatment system is slicker , and the enamel - dentine line is more regular than that prepared with an aerator . the necessity of using the mechanical nonrotatory instruments has emerged to eliminate the negative effects of the conventional methods . chemomechanical caries removal involves the selective removal of soft carious dentin without the painful removal of sound dentin . the carisolv system that is a popular chemomechanical system for caries removal consists of a gel with amino acids and sodium hypochlorite , and special hand instruments . one of the major advantages is the increased patient compliance to this technique of removing carious dentin compared to drills . in addition , unwanted removal of sound dentin is avoided and the need for local anesthesia is less . however , most of the studies reported that this method prolonged treatment time when compared with rotatory instruments [ 4 , 8 ] . it should be noted that there is as of yet no evidence in the current literature of using the vector system for minimal invasive cavity preparation ( in spite of manufacturer recommendations ) , and hence the initiation of this pilot study . but after applying this method , it is evident that there could be advantages such as high level of patient acceptance because of reduced pain response , reduced risk of injury due to other tissue sound pulp protection ( in deep lesions ) , high touch sensitivity and minimal use of water cooling ( aerosols eliminated and infection minimized ) . there are some limitations of the method such as reduced visualization due to suspended particles ( but there is a possibility of additional flushing of the preparation site ) , reduced removal rate compared with rotating burs , and the method is not suitable for the removal of extensive soft dentine caries . however , on the basis of the findings reported here , further research in a longer term prospective study comparing the vector system with a conventional approach using high speed burs , local analgesia , and a rubber dam is now needed [ 6 , 8 ] . the time required for preparation with the vector system was significantly longer ( 9.5 minutes for cs and 16.8 minutes for cm ) than when using conventional method ( cs 3.9 minutes , cm 5.5 minutes t-3.91 ;   p < .0002 ) . on the other hand , all results consistently showed a definite advantage of the rotatory instrument approach with respect to time . pain perception by hochmans scale showed that 54.8% of individuals treated by the use of the vector system did not experience any pain as opposed to 29.1% using the conventional method . rotatory instruments have some disadvantages , such as the nonselective removal of hard tissue , unpleasentness to the patients , necessity of local anesthesia , and potential adverse effects to the pulp due to heat and pressure [ 3 , 9 ] . it is suggested that the vector systems have higher patient acceptance , and reduced pain response ( sensitive children , anesthetic is often not needed ) [ 8 , 10 ] . the cavities prepared by a diamond bur in a conventional high - speed drill showed a box shaped configuration , with sharp cavo - surface edges and well - defined geometric internal angles , flat floor and wall cavity , with smear layer covering enamel and dentin surface in a typical morphological pattern as observed in freitas et al . in contrast to diamond instruments , the energy is transmitted indirectly via the silicon carbide particles carried in the water with the vector system . preparation with the vector system is therefore carried out without exposure to high temperatures and is extremely gentle on the pulp . loosening of the enamel prisms is avoided , which results in optimum marginal qualities for subsequent restorations , and with a lesser smear layer than cavity preparation with diamond bur . the present study determined that it is possible to remove carious tissue and perform cavity preparation with the vector system . according to both primary and permanent findings , evaluating surface quality , a cavity prepared with the vector treatment system has a cavity floor that is slicker and a more regular enamel - dentin line than a cavity prepared with an aerator . while being soundless , nonvibrating , and not using local anesthesia are advantages for clinical practice , a longer treatment time is a negative point , especially for young patients .
the aim of this study was to evaluate the vector system in comparison to the conventional technique in cavity preparation . 
 four extracted primary teeth with no restorations and similar fissure carious lesions and four permanent teeth extracted for orthodontic reasons were used . 
 class i preparations were made provided that the caries depth remained within the dentin limits . 
 two teeth were treated with an aerator , the other two had carious tissue removed with the vector system . 
 prepared cavities were evaluated with scanning electron microscopy for the surface roughness of the dentine and enamel and for the carious tissue removal efficiency . 
 this pilot study determined that it is possible to remove carious tissue and perform cavity preparation with the vector system . 
 according to this preliminary evaluation of surface quality , a cavity prepared with the vector treatment system , allows for a slicker floor , and a more regular enamel - dentine line than that prepared with an aerator . 
 however , the vector system requires a longer treatment time which we believe may be a negative point , especially for young patients .