d u r a tio n o f
$
mmmm
TOOTH COLOR CHANGE
AFTER BLEACHING
S T E P H E N F. R O S E N S T IE L, B .D .S ., M .S .D ., A N T H O N Y G. G E G A U F F , D .M .D ., W IL L IA M M. J O H N S T O N , PH .D .
( J ) any dentists currently offer their patients bleaching to lighten tooth color and enhance esthetics. The procedure, first proposed by Chappie in 1877,1was traditionally reserved for patients w ith intrinsic staining, such as from tetracycline. Recently, however, bleaching has become popular for patients who m erely w ant w hiter teeth. This renew ed interest in bleaching has coincided with the publication of a textbook2that described an in-office com bination of heat, light and 37 percent hydrogen peroxide and with a self adm inistered technique devised by Haywood and Heymann34using a vacuum formed sheet to deliver 10 p ercent carbam ine peroxide. Several m anufacturers have made variations on these m ethods available commercially. The biological effects of the heat/peroxide m ethod have been the subject of a num ber of studies th at concluded that any pulpal effects were reversible.^Using a rubber dam, ligatures and a barrier cream prevents contact betw een the peroxide and the soft tissues. There has been more concern about the effects of the self adm inistered systems, particularly w ith their longer-term use w ithout professional supervision.8 Few objective studies have m easured the color change after vital bleaching or duration of whitening. Most clinical reports on tetracycline staining suggest 54
JADA, Vol. 123, April 1991
ABSTRACT
Tooth color change was m onitored after a single, inoffice bleaching technique using a colorim eter. Twenty young adults participated in the double-blind study at The Ohio State University C ollege o f D entistry. H alf o f the participants had their m axillary anterior teeth bleached and h alf w ere controls. By one m onth, the large initial color change w as considerably reversed and only noticed by on e subject. A fter six months, the effect o f bleaching w as small, but still m easurable. variable results, particularly in severe cases with dark gray or blue staining. Severe staining is reported to require three to ten patient visits, each lasting 30 m inutes to 90 m inutes.2W hen treating unstained teeth, fewer visits m ight produce an acceptable result and would m ake the procedure less expensive and thereby m ore acceptable to the patient. Single-visit bleaching was supported by a previous colorim etric study on unstained extracted hum an teeth that showed that repeated bleaching produced very little color change in com parison with the initial treatm ent.9 In this study, we m easured w hether a single in-office
bleaching procedure produced perceivable tooth color change using a double-blind experim ental design with a randomly determ ined control group. We then m onitored the color differences over time. In addition, we asked the subjects to assess the procedure and the results. M E THO D S AND M A T E R IA L S
The 20 young adult subjects for the study (16 males, four females) were selected from non-smoking volunteer incoming dental students. Selection criteria included the presence of the six maxillary anterior teeth caries-free and unrestored, no abnormal tooth sensitivity, no previous bleaching treatm ent and no evidence of fluorosis or tetracycline staining. Mean age of the subjects at the time of treatm ent was 22.5 years (range: 20.2 years to 24.3 years). Ten subjects were randomly assigned to an “active bleaching” group and ten to a “mock bleaching” control group. The groups were not balanced with regard to the age, gender or ethnic origin of the subjects. Neither the investigators nor the subjects were inform ed as to which group an individual belonged. The subjects were instructed not to drink coffee or colored juices for one hour before each appointm ent. After 30 toothbrushing strokes with water,
The clinical procedure was Much better 2 r
than:
Better 1
Same 0
Worse -1
Much worse -2 Fig. 1. Subjects’ perception of vital bleaching as compared with some other dental procedures (expressed as a percentage of respondents with an experience of that procedure).
the midfacial area of each of the six anterior teeth was m easured with a small-area colorim eter (CR-121 Chroma Meter, Minolta) using custom-fabricated acrylic resin jigs to ensure repeatable positioning of the meter. Each tooth was m easured by positioning, removing and repositioning the colorim eter three times to obtain a m ean baseline color before treatm ent. The bleaching protocol closely followed th at described by Feinm an and others.2It consisted of isolating the teeth w ith a rubber dam using floss ligatures, pumicing and etching w ith 37 percent phosphoric acid, applying gauze saturated with 35 percent hydrogen peroxide (Superoxol, Union Broach) and exposing the teeth to a bleaching light (New Image, Union Broach) positioned at 300 millim eters w ith the num bered rheostat set at five. After 30 minutes, the teeth were flushed w ith water, the rubber dam removed, and the teeth polished with prophylaxis paste. The same procedure was used with
the control group except distilled w ater was used instead of the bleaching solution w ithout the explicit knowledge of the experim enter or the subject. It was not possible to tell by direct observation if the active solution or w ater was being used. About 15 m inutes after the polish, the teeth were m easured three times with the colorimeter,
again using the positioning jib. F urther m easurem ents were made at one week, one m onth, three m onths and at six to nine m onths. The color param eters were recorded in the L*a*b* color space as established by the Commission Internationale de L’Eclairage in 1978.10The approxim ate relationship between CIELAB coordinates and Munsell’s value, chroma and hue has been described previously.11The CIELAB system is related to hum an color perception in all three dim ensions or directions of color space. Equal distances in the color space represent approximately equally perceived steps. The colorimeter used in this study had a 45°/0° illum ination/ observation geometry which has correlated well with visual estim ates.12It has been used in several dental research studies including an in vitro bleaching study.9 We asked patients to complete a brief questionnaire about their perception of the in-office vital bleaching procedure a t the threem onth recall. The subjects were asked to com pare the procedure with other dental treatm ents they might have experienced, to state
Percent 40
N o c o lo r chance
2 w eeks
3-4 weeks
3+ months
Fig. 2. Subjects' perception of time whitening appeared to last (active subjects only).
JADA, Vol. 123, April 1991
55
TA BLE 1
REPEATED MEASURES MULTI VARIATE ANOVA OF CIELAR COLOR PARAMETER E* SO U R C E OF V A R IA T IO N
df
MEAN SQUARE
F VALUE
P
A D J. P
T E S T O F H Y P O T H E S E S FO R B E T W E E N -S U B J E C T E F F E C T S :
Group(G ) Error
1 18
390.8 19.9
19.95
$
mmmm
TOOTH COLOR CHANGE
AFTER BLEACHING
S T E P H E N F. R O S E N S T IE L, B .D .S ., M .S .D ., A N T H O N Y G. G E G A U F F , D .M .D ., W IL L IA M M. J O H N S T O N , PH .D .
( J ) any dentists currently offer their patients bleaching to lighten tooth color and enhance esthetics. The procedure, first proposed by Chappie in 1877,1was traditionally reserved for patients w ith intrinsic staining, such as from tetracycline. Recently, however, bleaching has become popular for patients who m erely w ant w hiter teeth. This renew ed interest in bleaching has coincided with the publication of a textbook2that described an in-office com bination of heat, light and 37 percent hydrogen peroxide and with a self adm inistered technique devised by Haywood and Heymann34using a vacuum formed sheet to deliver 10 p ercent carbam ine peroxide. Several m anufacturers have made variations on these m ethods available commercially. The biological effects of the heat/peroxide m ethod have been the subject of a num ber of studies th at concluded that any pulpal effects were reversible.^Using a rubber dam, ligatures and a barrier cream prevents contact betw een the peroxide and the soft tissues. There has been more concern about the effects of the self adm inistered systems, particularly w ith their longer-term use w ithout professional supervision.8 Few objective studies have m easured the color change after vital bleaching or duration of whitening. Most clinical reports on tetracycline staining suggest 54
JADA, Vol. 123, April 1991
ABSTRACT
Tooth color change was m onitored after a single, inoffice bleaching technique using a colorim eter. Twenty young adults participated in the double-blind study at The Ohio State University C ollege o f D entistry. H alf o f the participants had their m axillary anterior teeth bleached and h alf w ere controls. By one m onth, the large initial color change w as considerably reversed and only noticed by on e subject. A fter six months, the effect o f bleaching w as small, but still m easurable. variable results, particularly in severe cases with dark gray or blue staining. Severe staining is reported to require three to ten patient visits, each lasting 30 m inutes to 90 m inutes.2W hen treating unstained teeth, fewer visits m ight produce an acceptable result and would m ake the procedure less expensive and thereby m ore acceptable to the patient. Single-visit bleaching was supported by a previous colorim etric study on unstained extracted hum an teeth that showed that repeated bleaching produced very little color change in com parison with the initial treatm ent.9 In this study, we m easured w hether a single in-office
bleaching procedure produced perceivable tooth color change using a double-blind experim ental design with a randomly determ ined control group. We then m onitored the color differences over time. In addition, we asked the subjects to assess the procedure and the results. M E THO D S AND M A T E R IA L S
The 20 young adult subjects for the study (16 males, four females) were selected from non-smoking volunteer incoming dental students. Selection criteria included the presence of the six maxillary anterior teeth caries-free and unrestored, no abnormal tooth sensitivity, no previous bleaching treatm ent and no evidence of fluorosis or tetracycline staining. Mean age of the subjects at the time of treatm ent was 22.5 years (range: 20.2 years to 24.3 years). Ten subjects were randomly assigned to an “active bleaching” group and ten to a “mock bleaching” control group. The groups were not balanced with regard to the age, gender or ethnic origin of the subjects. Neither the investigators nor the subjects were inform ed as to which group an individual belonged. The subjects were instructed not to drink coffee or colored juices for one hour before each appointm ent. After 30 toothbrushing strokes with water,
The clinical procedure was Much better 2 r
than:
Better 1
Same 0
Worse -1
Much worse -2 Fig. 1. Subjects’ perception of vital bleaching as compared with some other dental procedures (expressed as a percentage of respondents with an experience of that procedure).
the midfacial area of each of the six anterior teeth was m easured with a small-area colorim eter (CR-121 Chroma Meter, Minolta) using custom-fabricated acrylic resin jigs to ensure repeatable positioning of the meter. Each tooth was m easured by positioning, removing and repositioning the colorim eter three times to obtain a m ean baseline color before treatm ent. The bleaching protocol closely followed th at described by Feinm an and others.2It consisted of isolating the teeth w ith a rubber dam using floss ligatures, pumicing and etching w ith 37 percent phosphoric acid, applying gauze saturated with 35 percent hydrogen peroxide (Superoxol, Union Broach) and exposing the teeth to a bleaching light (New Image, Union Broach) positioned at 300 millim eters w ith the num bered rheostat set at five. After 30 minutes, the teeth were flushed w ith water, the rubber dam removed, and the teeth polished with prophylaxis paste. The same procedure was used with
the control group except distilled w ater was used instead of the bleaching solution w ithout the explicit knowledge of the experim enter or the subject. It was not possible to tell by direct observation if the active solution or w ater was being used. About 15 m inutes after the polish, the teeth were m easured three times with the colorimeter,
again using the positioning jib. F urther m easurem ents were made at one week, one m onth, three m onths and at six to nine m onths. The color param eters were recorded in the L*a*b* color space as established by the Commission Internationale de L’Eclairage in 1978.10The approxim ate relationship between CIELAB coordinates and Munsell’s value, chroma and hue has been described previously.11The CIELAB system is related to hum an color perception in all three dim ensions or directions of color space. Equal distances in the color space represent approximately equally perceived steps. The colorimeter used in this study had a 45°/0° illum ination/ observation geometry which has correlated well with visual estim ates.12It has been used in several dental research studies including an in vitro bleaching study.9 We asked patients to complete a brief questionnaire about their perception of the in-office vital bleaching procedure a t the threem onth recall. The subjects were asked to com pare the procedure with other dental treatm ents they might have experienced, to state
Percent 40
N o c o lo r chance
2 w eeks
3-4 weeks
3+ months
Fig. 2. Subjects' perception of time whitening appeared to last (active subjects only).
JADA, Vol. 123, April 1991
55
TA BLE 1
REPEATED MEASURES MULTI VARIATE ANOVA OF CIELAR COLOR PARAMETER E* SO U R C E OF V A R IA T IO N
df
MEAN SQUARE
F VALUE
P
A D J. P
T E S T O F H Y P O T H E S E S FO R B E T W E E N -S U B J E C T E F F E C T S :
Group(G ) Error
1 18
390.8 19.9
19.95
