Dent Mater 8:60-64, January, 1992
Direct and indirect evaluation of posterior composite restorations at three years M~A. Freilich 1, A.J. Goldberg 1, R.O. Gilpatrick 2, R.J. Simonsen 3,4 Department of Prosthodontics, University of Connecticut, School of Dental Medicine, Farmington, CT USA 2General Dentistry, 3University of Tennessee, College of Dentistry, Memphis, TN USA 4US & International Dental Products Division, 3M Health Care, St. Paul, MN USA
Abstract. The purpose of this study was to compare the use of direct (USPHS) and indirect (M-L) systems of evaluating the occlusal wear of posterior composite restorations. Additionally, this study has utilized the USPHS method to compare the in vivo performance of posterior resin composite restorations made from four different visible-light-cured materials. Of the 202 restorations placed for this randomized clinical trial, only those restorations that were scored by both direct and indirect evaluation systems were included in these comparisons. Restorations were evaluated by two calibrated examiners from baseline to 36 months. While there were some differences noted among the four materials, the majority (99%) of the restorations evaluated in this study received "alpha" or "bravo" scores for all USPHS parameters, indicating acceptable in vivo performance. The results of this study also indicate that there was a consistent relationship between the direct (USPHS) and indirect (M-L scale) scoring systems. For those restorations that changed anatomic form scores, the mean wear at the alfa/bravo transition was 100 +80 microns. By the 24-month recall examination, the use of the USPHS evaluation system category of anatomic form enabled examiners to differentiate restorations and materials that had experienced little occlusal wear from those that had experienced greater amounts of wear. Recent activities in dental materials research have led to the development of composite restorative materials with muchimproved wear resistance. While the laboratory testing of these newer materials predicts great promise for their successful use in the restoration of posterior teeth, clinical trials are needed to test these materials in the intra-oral environment (Cunningham, 1989). These trials require objective, reliable, and clinically relevant criteria with which to make these assessments. In the early 1970's, Cvar and Ryge (1971) proposed an intraoral (direct) evaluation system, known as the USPHS method, which has been used to evaluate the performance of posterior resin composite restorations (Sturdevant et al., 1986; Feller et al., 1987; Tonn and Ryge, 1988; Sturdevant et. al., 1988; Rowe, 1989; Brunson et al., 1989; Lundin and Koch, 1989). This evaluation system was designed primarily to reflect differences in essence (acceptable/unacceptable), more than in degree. Some differences in degree, however, may be detected through the use of this system. Through the years, the USPHS method has proved to be both valid and reliable. There are several indirect evaluation systems that compare casts of restored teeth to a series of standards exhibiting
60 Freilich et aL/Direct and indirect evaluation of composites
incremental amounts ofocclusal wear. The Leinfelder method (Leinfelder et al., 1983) is widely used and employs a series of six replicas of restored teeth as known standards. The Lugassy and Moffa (1985) indirect evaluation system (the M-L scale) consists of 18 small cylinders with progressive depressions ranging from 0-1000 microns in depth. A system recently developed by Rheinberger (Bryant, 1990) for Ivoclar/Vivadent consists of tooth-sized stone replicas with restoration-like incremental defects ranging from 25-1000 microns. All of these systems have also proved to be reliable (Leinfelder et al., 1986; Goldberg et al., 1987; Bryant, 1990). Recently (1989), the Council on Dental Materials, Instruments and Equipment of the American Dental Association released new guidelines for the submission of composite materials for use as posterior restorative materials. These new guidelines include the use of the USPHS system for the direct evaluation of color match, marginal discoloration, caries, and marginal adaptation. Also included is the requirement that, at two years (as measured from six months), materials demonstrate no more than 50 and 125 microns of occlusal wear for the "unrestricted" and "restricted" categories, respectively. At four years, as measured from six months, these guidelines state that there should be no more than 100 and 175 microns for the "unrestricted" and"restricted" categories, respectively. If these amounts of occlusal wear are clinically detectable, a "direct" evaluation method may be well-suited for use in evaluating the occlusal wear of posterior composite restorations. In addition to the relative ease and decreased cost associated with the making of direct clinical evaluations, the difference in essence which these evaluations are designed to reflect is probably of greater interest to the clinician than the number of microns of wear measured by "indirect" methods. Comparisons of direct and indirect methods have indicated that the USPHS system has a limited ability to detect "early" changes in occlusal wear (Lutz et al., 1984; Goldberget al., 1984; Boksman et al. , 1986; Leinfelder et al. , 1986a; Vann et al. , 1988; Taylor et al., 1989). Taylor focused attention on the comparison between direct and indirect evaluations through the quantification of wear in microns measured when restorations exhibit a clinically detectable change in anatomic form at the occlusal surface. Their findings showed that evaluators were able to identify a clinically detectable change in anatomic form with the use of the USPHS system, and that a mean of 192 +_60 microns of wear was calculated at the alpha/bravo transition, as measured by the Leinfelder method. A more recent publication (Taylor et al., 1990), however, showed that this transition oc-
% iOO~o!. i f
°r
8o~
\ "~lfa
/ PHS Rating
t! ~
t
t
i
, "~
\~+-
"
40% -
2o~ -
evaluation included the intra-oral or "direct" assessment of
anatomic form, color match, secondary caries, marginal integrity, and marginal discoloration, with the use of the USPHS
Bravo PHS Rating
"-..,~
eo S 60%4 r a
~
" +~\\
j
\
o
n
S
0% 0-40
",,
~ I I i I '~, 50-90 100-140 150-190 200-240 250-290 300-39
Occlusal Wear in Microns OcclusaJ Wear derived
from M-L Scores
Fig. % Alfa and bravo scores by occlusal wear.
curs at 97 __40 microns when measured by the M-L scale. With consideration of the new ADA Guidelines concerning the occlusal wear of posterior composite restorations, the purpose of this study was to compare direct (USPHS) and indirect (M-L) evaluation systems. Additionally, this study has utilized the USPHS criteria to compare the in vivo performance of posterior resin composite restorations made from four different materials. MATERIALS AND METHODS Study Design.--Two hundred and two Class I and Class II restorations were placed in the posterior teeth of 46 healthy subjects for this randomized clinical trial. Some of these restorations were either conservative in size, covered by sealants, or placed on the buccal or lingual surfaces. The evaluation ofthese restorations will be described elsewhere. Of the remaining restorations, only those that had been scored by both direct and indirect evaluation systems were included for the comparisons reported in this paper. The sample sizes ranged from 90 to 142 restorations at the various re-call examinations. Four different visible-light-cured composites were used to make the restorations in this study. They include three hybrid composites ["J&J Experimental" (Johnson &Johnson, Skillman, NJ), "Marathon" (Den-Mat Inc., Santa Monica, CA), and"P-30" (3M Dental Products Division, St. Paul, MN)] and one microfill composite ["Heliomolar radiopaque" (Vivadent USA, Amherst, NY)]. All restorations were placed by one of two experienced operators. For the restorations described in this paper, the cavity preparations were all of conventional design used for amalgam restorations and were performed under optimal clinical conditions. The manufacturer's recommendations for each different material were followed throughout the various stages of tooth preparation, restoration placement, contouring, and finishing. Collection of Data.--The restorations were evaluated by two independent calibrated examiners at baseline, three months, six months, 12 months, 24 months, and 36 months. This
evaluation system (Cvar and Ryge, 1971). The USPHS evaluation system consists of a progressive rating scale where the first two scores of "alfa" and "bravo" of each category are considered to represent standards which are "clinically acceptable". The next progressive scores of"charlie" and "delta" represent evaluations which indicate unsatisfactory performance. A description of the anatomic form evaluation is shown in Table 1. For this study, the criteria used to define "bravo" scores were modified by including the loss of developmental grooves in the occlusal surface of the restoration. A consensus score was determined for all USPHS assessments of each restoration at each re-call exam. The indirect assessment of occlusal wear was evaluated through the use of stone replicas made from vinyl polysiloxane [Express, 3M Dental Products Division, St. Paul, MN] impressions of the experimental teeth. These replicas were independently scored by two examiners using the M-L scale (Lugassy and Moffa, 1985) to make comparisons ofthe wear ofthe replica restorations with the scale of 18 small cylinders with progressive depressions ranging from 0-1000 microns in depth. This scale is intended to be read in 25-micron increments from 0 to 100 microns, in 50-micron increments between 100 and 500 microns, and 100-micron steps from 500 to 1000 microns (1.0 mm). The examiners in this study, as well as examiners from other centers, have been able to differentiate intermediary values between the standard scores. Each examiner determined the overall average score for each restoration at the cavosurface margin. The two examiners' scores for each restoration were then averaged to obtain a mean score for each restoration at each re-call. The examiners were trained and calibrated prior to both the direct and indirect scoring of the restorations. Statistical Analysis.--The consensus USPHS scores and mean M-L measurements were used for data analysis. All data were recorded, keypunched, verified, and analyzed by use of an SPSS software package on an IBM PS-2 computer. The M-L measurements of wear were converted to microns and treated as parametric data. A one-way analysis of variance (ANOVA) was used to make comparisons between the data derived from the M-L measurements. A Chi-square analysis was used to compare the USPHS scores. RESULTS
Direct (USPHS) Evaluations.--When reviewing the clinical evaluations of these four posterior composites, it is important to recognize that, although there were some differences noted between and among materials, all but one of the 105 restorations evaluated at 36 months were considered to be "clinically acceptable" according to the USPHS evaluation system. There were no differences noted among the four composites with regard to the USPHS categories of caries, marginal adaptation, and marginal discoloration at all re-calls. The
TABLE 1: USPHS CRITERIA FOR RATING RESTORATIONS FOR ANATOMIC FORM (Wear)
Alfa
Restoration is continuous with existing anatomical form.
Bravo
Restorationis discontinuouswith existinganatomical form, but missingmaterialis not sufficientto exposedentinor base.
Charlie
Sufficient materialis lost to exposedentinor base.
Vann et al., 1988.
Dental Materials~January 1992 61
TABLE 2: PERCENTAGEOF "ALFA"SCORESAT BASELINEAND 36 MONTHSFOR USPHSCATEGORIES WHERE NO STATISTICALDIFFERENCESWERE DETECTEDBETWEENMATERIALS Heliomolar
J&J EXD
Marathon
P-30
Baseline
36 Mo
Baseline
36 Mo
Baseline
36 Mo
Baseline
36 Mo
n= 14
n= 12
n=46
n =44
n=32
n=29
n= 13
n=20
MarginalDisco~ration
100
100
98
100
100
97
100
go
SecondaryCaries
100
100
100
100
100
100
100
100
Marg~alAdap~tion
100
100
100
86
100
90
100
100
Note: All otherscoresare "bravo"exceptfor 3% "delta"scoresfor marginaladaptationat 36 monthsfor Marathon.
data and the comparisons made among materials for these categories can be seen in Table 2. This Table demonstrates that there was little or no change in these scores over time, and that there was a very low percentage of"bravo" scores for all of these categories at all exams. As seen in Table 3, there was a significant difference (p < 0.05) in scores for anatomic form between Marathon and the other three resin composites at 24 and 36 months. Values at 36 months were 72% and 32-42% "bravo" scores, respectively. There were, however, no "charlie" scores given for any of the materials at any of the re-calls. All color match scores were also found to be "bravo" or better. Therefore, no restorations were evaluated to be outside the normal range of tooth color. The percent agreement between examiners for all USPHS scores (for all categories and re-calls) was 85% or better, with the exception of the categories of anatomic form at 36 months and color match at 24 and 36 months, where the percent agreement was 66 and 77-78%, respectively. This decreased percent agreement for anatomic form coincides with the increase in the number of restorations making the transition from"alfa" to "bravo" scores.
Comparison between USPHS Scores and M-L Scale Measurements.--The mean M-L wear in microns for all restorations with "alfa" and "bravo" USPHS scores for anatomic form is shown in Table 4. At the 36-month re-call, those restorations that were given "alfa" anatomic form scores had a mean (M-L) occlusal wear of 55 _+ 48 microns, which was significantly different (p < 0.01) from those restorations that had "bravo" scores, which had a mean occlusal wear of 121 + 90 microns. The Fig. compares the percentages of restorations (for all recalls combined) with"alfa" and "bravo" anatomic form scores at increasing amounts ofM-L occlusal wear. As expected, this Fig. shows that there was a consistent relationship between the direct (USPHS) and indirect (M-L scale) scoring systems used in this study. Restorations with low M-L measurements are more likely to be rated "alfa", while those with high M-L measurements are more likely to be rated "bravo". Between approximately 150 and 290 microns of wear, a restoration has an equal chance of receiving either an "alfa" or a "bravo" score. The mean wear at the "alfa" to "bravo" transition was determined by averaging the occlusal wear measured for these restorations at that exam where the "bravo" was first scored with the occlusal wear for those same restorations at the prior exam (Taylor et al., 1989). The mean wear at this alfa/bravo transition was 100 _+80 microns. Five of the 51 restorations (9.8%) that were scored as "bravo" for anatomic form were scored "alfa" at the next re-call. The mean occlusal wear for these five restorations was 82 _+27 microns, which was not significantly different from the remainder of the "bravo"-scored restorations, whose
62 Freilich et aL/Direct and indirect evaluation of composites
mean wear was 116 + 88 microns. Table 5 compares the abilities of the M-L and USPHS systems to detect differences between and among materials. Note that the use of the M-L scale detected a difference between Marathon and the other three materials by the three-month exam, while the USPHS system detected the difference between Marathon and the other materials at the 24-month exam. DISCUSSION At three years, 99% of the 105 restorations evaluated for this study continued to function satisfactorily. With regard to the USPHS or direct evaluations, there were no differences seen among the four light-cured composites with regard to the caries, marginal adaptation, and marginal discoloration categories. There were, however, significant differences in anatomic form seen between Marathon and the other three materials at both 24 and 36 months. Additionally, while all color match scores were found to be "bravo" or better, the J&J Experimental restorations had significantly more "bravo" scores than the other restorations, even at baseline. This was not due to any apparent color instability, but resulted from the fact that this material was only available in one shade at the time of restoration placement. The J&J Experimental material is now marketed under the proprietary name of "Adaptic II", and is currently available in a variety of shades. As stated earlier, recently reported clinical trials have utilized the USPHS criteria to evaluate the clinical performance of posterior composites. Most of these studies have found a very high percentage of "alfa" USPHS scores for caries, marginal adaptation, marginal discoloration, and color match from three- to five-year observation periods. Many of these studies also reported a notably higher percentage of"bravo" scores for
TABLE 3: PERCENTAGEOF USPHS"BRAVO"ANATOMIC FORMSCORES FOR ALL MATERIALS Re-call
Heliornolar J&J Exp Marathon
P-30 Significance
Baseline
0
0
0
0
NS
3 Months
0
0
0
0
NS
6 Months
0
0
0
0
NS
12 Months
5
2
10
4
NS
24 Months
0
5
28*
10
p < 0.05
36 Months
42
32
72*
42
p < 0.05
*Denotesmaterialthat is significantlydifferentfrom the otherthree materials.
TABLE 4: MEANOCCLUSALWEAR IN MICRONSFOR USPHSANATOMICFORMSCORES Alfa
Bravo
M e a n S.D.
n
M e a n S.D.
Statistical Difference
Total n
n
Baseline
105
105
4
8
3 months
90
90
21
20
6 months
98
98
33
30
12 months
142
135
47
47
7
95
46
p < 0.01
24 months
111
98
69
63
13
124
81
p
Direct and indirect evaluation of posterior composite restorations at three years M~A. Freilich 1, A.J. Goldberg 1, R.O. Gilpatrick 2, R.J. Simonsen 3,4 Department of Prosthodontics, University of Connecticut, School of Dental Medicine, Farmington, CT USA 2General Dentistry, 3University of Tennessee, College of Dentistry, Memphis, TN USA 4US & International Dental Products Division, 3M Health Care, St. Paul, MN USA
Abstract. The purpose of this study was to compare the use of direct (USPHS) and indirect (M-L) systems of evaluating the occlusal wear of posterior composite restorations. Additionally, this study has utilized the USPHS method to compare the in vivo performance of posterior resin composite restorations made from four different visible-light-cured materials. Of the 202 restorations placed for this randomized clinical trial, only those restorations that were scored by both direct and indirect evaluation systems were included in these comparisons. Restorations were evaluated by two calibrated examiners from baseline to 36 months. While there were some differences noted among the four materials, the majority (99%) of the restorations evaluated in this study received "alpha" or "bravo" scores for all USPHS parameters, indicating acceptable in vivo performance. The results of this study also indicate that there was a consistent relationship between the direct (USPHS) and indirect (M-L scale) scoring systems. For those restorations that changed anatomic form scores, the mean wear at the alfa/bravo transition was 100 +80 microns. By the 24-month recall examination, the use of the USPHS evaluation system category of anatomic form enabled examiners to differentiate restorations and materials that had experienced little occlusal wear from those that had experienced greater amounts of wear. Recent activities in dental materials research have led to the development of composite restorative materials with muchimproved wear resistance. While the laboratory testing of these newer materials predicts great promise for their successful use in the restoration of posterior teeth, clinical trials are needed to test these materials in the intra-oral environment (Cunningham, 1989). These trials require objective, reliable, and clinically relevant criteria with which to make these assessments. In the early 1970's, Cvar and Ryge (1971) proposed an intraoral (direct) evaluation system, known as the USPHS method, which has been used to evaluate the performance of posterior resin composite restorations (Sturdevant et al., 1986; Feller et al., 1987; Tonn and Ryge, 1988; Sturdevant et. al., 1988; Rowe, 1989; Brunson et al., 1989; Lundin and Koch, 1989). This evaluation system was designed primarily to reflect differences in essence (acceptable/unacceptable), more than in degree. Some differences in degree, however, may be detected through the use of this system. Through the years, the USPHS method has proved to be both valid and reliable. There are several indirect evaluation systems that compare casts of restored teeth to a series of standards exhibiting
60 Freilich et aL/Direct and indirect evaluation of composites
incremental amounts ofocclusal wear. The Leinfelder method (Leinfelder et al., 1983) is widely used and employs a series of six replicas of restored teeth as known standards. The Lugassy and Moffa (1985) indirect evaluation system (the M-L scale) consists of 18 small cylinders with progressive depressions ranging from 0-1000 microns in depth. A system recently developed by Rheinberger (Bryant, 1990) for Ivoclar/Vivadent consists of tooth-sized stone replicas with restoration-like incremental defects ranging from 25-1000 microns. All of these systems have also proved to be reliable (Leinfelder et al., 1986; Goldberg et al., 1987; Bryant, 1990). Recently (1989), the Council on Dental Materials, Instruments and Equipment of the American Dental Association released new guidelines for the submission of composite materials for use as posterior restorative materials. These new guidelines include the use of the USPHS system for the direct evaluation of color match, marginal discoloration, caries, and marginal adaptation. Also included is the requirement that, at two years (as measured from six months), materials demonstrate no more than 50 and 125 microns of occlusal wear for the "unrestricted" and "restricted" categories, respectively. At four years, as measured from six months, these guidelines state that there should be no more than 100 and 175 microns for the "unrestricted" and"restricted" categories, respectively. If these amounts of occlusal wear are clinically detectable, a "direct" evaluation method may be well-suited for use in evaluating the occlusal wear of posterior composite restorations. In addition to the relative ease and decreased cost associated with the making of direct clinical evaluations, the difference in essence which these evaluations are designed to reflect is probably of greater interest to the clinician than the number of microns of wear measured by "indirect" methods. Comparisons of direct and indirect methods have indicated that the USPHS system has a limited ability to detect "early" changes in occlusal wear (Lutz et al., 1984; Goldberget al., 1984; Boksman et al. , 1986; Leinfelder et al. , 1986a; Vann et al. , 1988; Taylor et al., 1989). Taylor focused attention on the comparison between direct and indirect evaluations through the quantification of wear in microns measured when restorations exhibit a clinically detectable change in anatomic form at the occlusal surface. Their findings showed that evaluators were able to identify a clinically detectable change in anatomic form with the use of the USPHS system, and that a mean of 192 +_60 microns of wear was calculated at the alpha/bravo transition, as measured by the Leinfelder method. A more recent publication (Taylor et al., 1990), however, showed that this transition oc-
% iOO~o!. i f
°r
8o~
\ "~lfa
/ PHS Rating
t! ~
t
t
i
, "~
\~+-
"
40% -
2o~ -
evaluation included the intra-oral or "direct" assessment of
anatomic form, color match, secondary caries, marginal integrity, and marginal discoloration, with the use of the USPHS
Bravo PHS Rating
"-..,~
eo S 60%4 r a
~
" +~\\
j
\
o
n
S
0% 0-40
",,
~ I I i I '~, 50-90 100-140 150-190 200-240 250-290 300-39
Occlusal Wear in Microns OcclusaJ Wear derived
from M-L Scores
Fig. % Alfa and bravo scores by occlusal wear.
curs at 97 __40 microns when measured by the M-L scale. With consideration of the new ADA Guidelines concerning the occlusal wear of posterior composite restorations, the purpose of this study was to compare direct (USPHS) and indirect (M-L) evaluation systems. Additionally, this study has utilized the USPHS criteria to compare the in vivo performance of posterior resin composite restorations made from four different materials. MATERIALS AND METHODS Study Design.--Two hundred and two Class I and Class II restorations were placed in the posterior teeth of 46 healthy subjects for this randomized clinical trial. Some of these restorations were either conservative in size, covered by sealants, or placed on the buccal or lingual surfaces. The evaluation ofthese restorations will be described elsewhere. Of the remaining restorations, only those that had been scored by both direct and indirect evaluation systems were included for the comparisons reported in this paper. The sample sizes ranged from 90 to 142 restorations at the various re-call examinations. Four different visible-light-cured composites were used to make the restorations in this study. They include three hybrid composites ["J&J Experimental" (Johnson &Johnson, Skillman, NJ), "Marathon" (Den-Mat Inc., Santa Monica, CA), and"P-30" (3M Dental Products Division, St. Paul, MN)] and one microfill composite ["Heliomolar radiopaque" (Vivadent USA, Amherst, NY)]. All restorations were placed by one of two experienced operators. For the restorations described in this paper, the cavity preparations were all of conventional design used for amalgam restorations and were performed under optimal clinical conditions. The manufacturer's recommendations for each different material were followed throughout the various stages of tooth preparation, restoration placement, contouring, and finishing. Collection of Data.--The restorations were evaluated by two independent calibrated examiners at baseline, three months, six months, 12 months, 24 months, and 36 months. This
evaluation system (Cvar and Ryge, 1971). The USPHS evaluation system consists of a progressive rating scale where the first two scores of "alfa" and "bravo" of each category are considered to represent standards which are "clinically acceptable". The next progressive scores of"charlie" and "delta" represent evaluations which indicate unsatisfactory performance. A description of the anatomic form evaluation is shown in Table 1. For this study, the criteria used to define "bravo" scores were modified by including the loss of developmental grooves in the occlusal surface of the restoration. A consensus score was determined for all USPHS assessments of each restoration at each re-call exam. The indirect assessment of occlusal wear was evaluated through the use of stone replicas made from vinyl polysiloxane [Express, 3M Dental Products Division, St. Paul, MN] impressions of the experimental teeth. These replicas were independently scored by two examiners using the M-L scale (Lugassy and Moffa, 1985) to make comparisons ofthe wear ofthe replica restorations with the scale of 18 small cylinders with progressive depressions ranging from 0-1000 microns in depth. This scale is intended to be read in 25-micron increments from 0 to 100 microns, in 50-micron increments between 100 and 500 microns, and 100-micron steps from 500 to 1000 microns (1.0 mm). The examiners in this study, as well as examiners from other centers, have been able to differentiate intermediary values between the standard scores. Each examiner determined the overall average score for each restoration at the cavosurface margin. The two examiners' scores for each restoration were then averaged to obtain a mean score for each restoration at each re-call. The examiners were trained and calibrated prior to both the direct and indirect scoring of the restorations. Statistical Analysis.--The consensus USPHS scores and mean M-L measurements were used for data analysis. All data were recorded, keypunched, verified, and analyzed by use of an SPSS software package on an IBM PS-2 computer. The M-L measurements of wear were converted to microns and treated as parametric data. A one-way analysis of variance (ANOVA) was used to make comparisons between the data derived from the M-L measurements. A Chi-square analysis was used to compare the USPHS scores. RESULTS
Direct (USPHS) Evaluations.--When reviewing the clinical evaluations of these four posterior composites, it is important to recognize that, although there were some differences noted between and among materials, all but one of the 105 restorations evaluated at 36 months were considered to be "clinically acceptable" according to the USPHS evaluation system. There were no differences noted among the four composites with regard to the USPHS categories of caries, marginal adaptation, and marginal discoloration at all re-calls. The
TABLE 1: USPHS CRITERIA FOR RATING RESTORATIONS FOR ANATOMIC FORM (Wear)
Alfa
Restoration is continuous with existing anatomical form.
Bravo
Restorationis discontinuouswith existinganatomical form, but missingmaterialis not sufficientto exposedentinor base.
Charlie
Sufficient materialis lost to exposedentinor base.
Vann et al., 1988.
Dental Materials~January 1992 61
TABLE 2: PERCENTAGEOF "ALFA"SCORESAT BASELINEAND 36 MONTHSFOR USPHSCATEGORIES WHERE NO STATISTICALDIFFERENCESWERE DETECTEDBETWEENMATERIALS Heliomolar
J&J EXD
Marathon
P-30
Baseline
36 Mo
Baseline
36 Mo
Baseline
36 Mo
Baseline
36 Mo
n= 14
n= 12
n=46
n =44
n=32
n=29
n= 13
n=20
MarginalDisco~ration
100
100
98
100
100
97
100
go
SecondaryCaries
100
100
100
100
100
100
100
100
Marg~alAdap~tion
100
100
100
86
100
90
100
100
Note: All otherscoresare "bravo"exceptfor 3% "delta"scoresfor marginaladaptationat 36 monthsfor Marathon.
data and the comparisons made among materials for these categories can be seen in Table 2. This Table demonstrates that there was little or no change in these scores over time, and that there was a very low percentage of"bravo" scores for all of these categories at all exams. As seen in Table 3, there was a significant difference (p < 0.05) in scores for anatomic form between Marathon and the other three resin composites at 24 and 36 months. Values at 36 months were 72% and 32-42% "bravo" scores, respectively. There were, however, no "charlie" scores given for any of the materials at any of the re-calls. All color match scores were also found to be "bravo" or better. Therefore, no restorations were evaluated to be outside the normal range of tooth color. The percent agreement between examiners for all USPHS scores (for all categories and re-calls) was 85% or better, with the exception of the categories of anatomic form at 36 months and color match at 24 and 36 months, where the percent agreement was 66 and 77-78%, respectively. This decreased percent agreement for anatomic form coincides with the increase in the number of restorations making the transition from"alfa" to "bravo" scores.
Comparison between USPHS Scores and M-L Scale Measurements.--The mean M-L wear in microns for all restorations with "alfa" and "bravo" USPHS scores for anatomic form is shown in Table 4. At the 36-month re-call, those restorations that were given "alfa" anatomic form scores had a mean (M-L) occlusal wear of 55 _+ 48 microns, which was significantly different (p < 0.01) from those restorations that had "bravo" scores, which had a mean occlusal wear of 121 + 90 microns. The Fig. compares the percentages of restorations (for all recalls combined) with"alfa" and "bravo" anatomic form scores at increasing amounts ofM-L occlusal wear. As expected, this Fig. shows that there was a consistent relationship between the direct (USPHS) and indirect (M-L scale) scoring systems used in this study. Restorations with low M-L measurements are more likely to be rated "alfa", while those with high M-L measurements are more likely to be rated "bravo". Between approximately 150 and 290 microns of wear, a restoration has an equal chance of receiving either an "alfa" or a "bravo" score. The mean wear at the "alfa" to "bravo" transition was determined by averaging the occlusal wear measured for these restorations at that exam where the "bravo" was first scored with the occlusal wear for those same restorations at the prior exam (Taylor et al., 1989). The mean wear at this alfa/bravo transition was 100 _+80 microns. Five of the 51 restorations (9.8%) that were scored as "bravo" for anatomic form were scored "alfa" at the next re-call. The mean occlusal wear for these five restorations was 82 _+27 microns, which was not significantly different from the remainder of the "bravo"-scored restorations, whose
62 Freilich et aL/Direct and indirect evaluation of composites
mean wear was 116 + 88 microns. Table 5 compares the abilities of the M-L and USPHS systems to detect differences between and among materials. Note that the use of the M-L scale detected a difference between Marathon and the other three materials by the three-month exam, while the USPHS system detected the difference between Marathon and the other materials at the 24-month exam. DISCUSSION At three years, 99% of the 105 restorations evaluated for this study continued to function satisfactorily. With regard to the USPHS or direct evaluations, there were no differences seen among the four light-cured composites with regard to the caries, marginal adaptation, and marginal discoloration categories. There were, however, significant differences in anatomic form seen between Marathon and the other three materials at both 24 and 36 months. Additionally, while all color match scores were found to be "bravo" or better, the J&J Experimental restorations had significantly more "bravo" scores than the other restorations, even at baseline. This was not due to any apparent color instability, but resulted from the fact that this material was only available in one shade at the time of restoration placement. The J&J Experimental material is now marketed under the proprietary name of "Adaptic II", and is currently available in a variety of shades. As stated earlier, recently reported clinical trials have utilized the USPHS criteria to evaluate the clinical performance of posterior composites. Most of these studies have found a very high percentage of "alfa" USPHS scores for caries, marginal adaptation, marginal discoloration, and color match from three- to five-year observation periods. Many of these studies also reported a notably higher percentage of"bravo" scores for
TABLE 3: PERCENTAGEOF USPHS"BRAVO"ANATOMIC FORMSCORES FOR ALL MATERIALS Re-call
Heliornolar J&J Exp Marathon
P-30 Significance
Baseline
0
0
0
0
NS
3 Months
0
0
0
0
NS
6 Months
0
0
0
0
NS
12 Months
5
2
10
4
NS
24 Months
0
5
28*
10
p < 0.05
36 Months
42
32
72*
42
p < 0.05
*Denotesmaterialthat is significantlydifferentfrom the otherthree materials.
TABLE 4: MEANOCCLUSALWEAR IN MICRONSFOR USPHSANATOMICFORMSCORES Alfa
Bravo
M e a n S.D.
n
M e a n S.D.
Statistical Difference
Total n
n
Baseline
105
105
4
8
3 months
90
90
21
20
6 months
98
98
33
30
12 months
142
135
47
47
7
95
46
p < 0.01
24 months
111
98
69
63
13
124
81
p
