- Email: [email protected]
Effect of restoration quality on periodontal health
DEUTSCH
displace it. The threads are also 1 mm apart, so 1 mm of dentin between each thread must be crushed before the post is loosened. This may require an inordinate amount of force. The Flexi-Post also has a wide-diameter, threaded, second tier that may be responsible for additional retention. It was noted in the second part of the study that as the size of the Flexi-Post increased, the magnitude of force required for dislodgment also increased. Because both the length and the diameter of the post increases as the post size increases, it is difficult to determine which dimension was more responsible for the increased retention of the post.
SUMMARY AND CONCLUSIONS
REFERENCES Guzy, G. E., and Nicholls, J. I.: In vitro comparison of intact endodontically treated teeth with and without endo-post reinforcement. J PROSTHET DENT 4!2:39, 1979. 2. Trabert, K. C., Caputo, A. A.. and Abou-Ross, M.: Tooth fracture-A comparison of endodontic and and restorative treatments. J Endodont 4~341, 1978. 3. Deutsch, A. S., Musikant, B. L., Cavallari, J., and Lepley, J. B.. Prefabricated dowels: A literature review. J PROSTHET DEKI 49~498, 1983. 4. Standlee, J. P., Caputo, A. A., and Hanson, E. C.: Retention ot endodontic dowels: Effects of cement, dowel length, diameter, and design. J PROSTHET DENT 39~401, 1978. 5. Standlee, J. P.. Caputo, A. A., Holcomb, J., and Trabert, K. C.: The retentive and stress-distributing properties of a threaded endodontic dowel. J PROSTHET DENT 44~398. 1980. 1.
Hepnnt requeststo:
Fifty Flexi-Posts were cemented in extracted teeth and tested for tensile strength. 1. The Flexi-Post was the most retentive post tested when compared with posts used in a similar study. 2. The retention of the Flexi-Post became greater as the size of the post increased.
DR. ALLAN S. DEUTSC:H 119 W. 57~~ ST., STE. 700 NEW YORK, NY 10019
Joseph E. Grasso, D.D.S., M.S.,* John NlhbPndian, D.M.D.,** Howard Bailit, D.M.D., Ph.D.‘**+ University
of Connecticut,
School of Dental
Medicine,
Collin Sanford, D.M*D.,***
and
Farmington, Conn.
T
he development of a dental quality assurance policy requires information on three basic issues: (1) the adequacy of dental care in the general population of dental patients, (2) the relationship between inadequate quality care and oral health, and (3) the relative importance of quality care compared with other factors that influence oral health. With this information, policy makers could determine the need for a formal quality assurance system, the form the system might take, and the improvements in oral health that could reasonably be achieved by such a system. In the first report of this series, Grasso et al.’ described the technical quality of restorative care in a sample of 291 adults. They reported that the quahty of Supported by Grant No. 336-75 from the University of Connecticut Research Foundation. *Professor, Department of Restorative Dentistry. **Professor, Department of Periodontology. ***Assistant Professor, Department of Restorative Dentistry. ****Professor, Department of Behavioral Sciences and Community Health. 14
ET AL
amalgam, composite resin, and cast restorations was relatively high for all categories. In contrast, individual crowns, retainers, and pontics were substantially less adequate. In this article, data from the same project are used to investigate the relationship between the quality of restorative dental care and periodontal health. Previous research in animals and humans indicates that (1) there is greater marginal inflammation associated with subgingival restorations when compared with supragingival restorations, (2) better fit and finish of the margins have a significant positive effect on gingival health, and (3) restored teeth are associated with greater inflammation than unrestored teeth.2”Z Other articles have shown that there is a relationship between plaque accumulation caused by inadequate restorations and periodontal disease.2~‘“. “. I3 Building on the previous report, the objectives of the present study were (1) to quantify the effects of inadequate restorations on the health of periodontal tissues, (2) to compare the relative importance of restoration quality with other factors that influence periodontal JANUARY
1985
VOLUME
53
NUMBER
1
RESTORATION QUALITY AND PERIODONTAL
Table I. Analysis
of variance
HEALTH
for amalgams* Gingival cavosurface margin
Plaque Inadequate Adequate No restoration Calculus Inadequate Adequate No restoration Gingivitis Inadequate Adequate No restoration Pocket depth Inadequate Adequate No restoration
Embrasures
Marginal
ridges
No.
x
No.
x
No.
x
414 1633 6126
1.20 1.05 1.05
302 1624 6247
1.15 1.07 1.05
240 1636 6297
1.18 1.07 1.05
412 1621 6137
.43 .33 .47
301 1611 6258
.41 .31 .47
239 1623 6308
.46 .30 .47
414 1633 6129
1.26 1.16 1.01
302 1624 6250
1.25 1.18 1.01
240 1636 6300
1.26 1.19 1.01
414 1632 6118
3.31 3.17 3.03
302 1623 6239
3.21 3.18 3.04
240 1635 6289
3.20 3.19 3.04
x = Mean of sample. *Effects of unrestored, adequately restored, and inadequately restored teeth on plaque, calculus, gingivitis, and pocket depths. Data on mesial and distal surfaces of molars and premolars are included. All ANOVA’s are statistically significant CI, < .Ol).
health, and (3) to consider the results of the study in the context of national policies on dental quality assurance systems. METHOD Notices were sent to all University of Connecticut Health Center employees (excluding students) to request their participation in the study. Three mailings resulted in the appearance of 291 people, a response rate of about 13%. For each subject, an assessment of the technical quality of individual tooth restorations, crowns and fixed partial dentures and oral health status was made.’ Examinations were performed with mirror, explorer, and Michigan probe (Hu Friedy, Chicago, Ill.), without the use of radiographs. Subjects also completed a questionnaire that provided information on their sociodemographic characteristics, use of dental services, oral hygiene practices, and attitudes and knowledge of dentistry. The technical quality of restorative and prosthetic services was assessedby explicit criteria developed and tested by Bailit et al. I4 The criteria relate to the following services: amalgam restorations, single crowns, retainers, and pontics. Each restoration is rated for several quality categories, such as occlusion and gingival cavosurface margins. Each category has explicit criteria that define adequate care. A category is scored adequate if ail criteria are met. An inadequate score is assigned when one or more criteria are not met. The percent of adequate scores can be averaged per criterion and per quality category or per tooth surface, restoration, and mouth. THE JOURNAL OF PROSTHETIC DENTISTRY
The oral health variables of interest, gingival inflammation and periodontal pocket depth, were measured with the gingivitis index of Liie and Silnessi5 and probing at six locations per tooth with a standardized technique. Plaque was measured by the method of Silness and L6e.16 Calculus was assessedby a modified Ramfjord calculus index.” All teeth except third molars were included in the study. Three faculty members from the University of Connecticut School of Dental Medicine participated in the examination of subjects. Each subject was examined by two participants; the oral health, plaque, and calculus data were first collected by one examiner and the restoration quality was assessedby the other examiner. All examiners were initially trained for 12 hours in the use of the indexes, during which time 25 subjects were each seen independently by pairs of examiners to determine inter-rater reliability. As noted in the previous article on this project, reliability levels were within acceptable limits.’ Two approaches were used to determine the relationship between oral health and the technical quality of care. First, analysis of variance (ANOVA) was used to compare the effects of no restoration, an adequate restoration, and an inadequate restoration on plaque accumulation, calculus deposits, gingivitis, and periodontal pocket depths. This was done for each of the following types of restorations: amalgam restorations with two or more surfaces, single crowns, and retainer crowns. The second approach involved the use of a multiple stepwise regression to relate quality variation to oral 15
GRASS0
Table II. Analysis of variance --___
for crowns*
Gingival cavosurface margins No. Plaque Inadequate Adequate No restoration Calculus Inadequate Adequate No restoration Gingivitis Inadequate Adequate No restoration Pocket depth Inadequate Adequate No restoration
ET Ai.
79 149 14,729 79 141 14,724
Embrasures x
.87 1.09 .99 ,139 ,092 s20
Marginal
ridges
No.
x
No.
x
219 542 29.497
.88 .81 .?I
2: 257 29,974
1.11
213 532 29.490
.34 .14 .40
27 251 29.957 L
79 149 14,732
1.35 1.36 .95
219 542 29,504
1.25 1.09 .75
79 149 14,719
3.31 3.19 2.77
219 542 29,486
2.73 2.67 2.19
i
I 01 .I-1
27 257 29,981 87 257 29,963
3.18 3.21 2.20
x = hlean of the sample. *Effects of unrestored, adequately restored, and inadequately restored teeth on plaque, calculus, gingivitis, and pocket depths. Data on mesial and distal surfaces of molars and premolars are included. All ANOVA’s are statistically significant (p < ,011.
health, with controls for several intervening variables. At issue was the relative importance of restoration quality to periodontal health compared with several patientrelated variables that are essentially beyond the control of the dentist. This analysis was undertaken at the level of the entire dentition and specific surfaces. The dentition analysis allowed investigation of the effects of quality variation on restored and unrestored teeth. The relevant question is whether poor quality restorations in some teeth lead to a general increase in gingivitis and pocket depths throughout the mouth. The analysis at the tooth surface level permitted determination of the association between an inadequately restored surface and gingivitis and pocket depth at that surface. The intervening variables in the multiple stepwise regression were patient age, education, family income, number of visits to the dentist in the past two years, plaque levels, and calculus scores. In terms of the predicted effect of the variables, patient age is associated with increasing periodontal disease, and hence pocket depth should increase in older patients.‘* Gingivitis is also positively related to age but to a lesser extent, especially in adults.” Patient education level measured in years of schooling is related to oral hygiene practices, which in turn influence gingivitis and periodontal disease.‘* Those with more years of education are expected to have less gingivitis and shallower pockets. Patient income is closely related to education and should have the same general effect. I8 Considered separately, education should have a greater effect than income.‘* 16
Number of visits to a dentist in the past two years provided an estimate of the subject’s use of dental services. Other studies have shown that people who receive periodic dental care have less plaque and gingivitis and fewer periodontal pockets.‘9,2”Plaque levels are closely and positively related to gingivitis and increased pocket depth. 21 The separate effects of calculus and periodontal pocket depths are not entirely clear, because both are closely associated with plaque accumulations. RESULTS Table I presents the ANOVA that compared plaque, calculus, gingivitis, and pocket depth scores for unrestored, adequately restored, and inadequately restored Class II amalgam restorations (molars and premolars). The data were available for three aspects of restoration quality: gingival cavosurface margins, embrasures, and marginal ridges. In general, the results indicated that among the three dimensions of amalgam quality, inadequate gingival cavosurface margins had the most negative effect on the health of the periodontium. However, there was a moderate association among quality ratings in the three dimensions of restoration quality (correlation coefficients of 0.4 to 0.6, p <.05). This means that restorations rated inadequate on one quality dimension tend to be rated inadequate for the others as well. Thus, it was difficult to determine their independent effects on periodontal health. Table I also indicates that the mean plaque, gingivitis, and pocket depth scores were highest for inadequate restorations. As with previous studies, poor quality restorations were associated with greater plaque accuJANUARY
1985
VOLUME
53
NUMBER
1
RESTORATION
QUALITY
Table III. Analysis
AND
PERIODONTAL
of variance
HEALTH
for crown retainers*
Gingival cavosurface margins
Plaque Inadequate Adequate No restoration Calculus Inadequate Adequate No restoration Gingivitis Inadequate Adequate No restoration Pocket depth Inadequate Adequate No restoration
Marginal
Embrasures No.
x
.88 .81 .71
27 257 29,974
1.14 1 .Ol .71
213 532 29,490
.34 .I4 .40
27 251 29,957
.ll .I2 .39
1.44 1.08 .95
219 542 29,504
1.25 1.09 .75
27 257 29,981
1.44 1.33 .75
3.40 3.23 2.77
219 542 29,486
2.73 2.67 2.19
87 257 29,963
3.18 3.21 2.20
No.
R
No.
47 127 14,729
1.61 1.07 .99
219 542 29,497
47 127 14,724
.87 .I8 .52
47 127 14,732 47 127 14,719
x
ridges
X = Mean of the sample. *Effects of unrestored, adequately restored, and inadequately restored teeth on plaque, calculus, gingivitis, and pocket depths. Data on mesial and distal surfaces of molars and premolars are included. All ANOVA’s are statistically significant (,b < .Ol).
mulation and presumably in turn with more gingivitis and pocket development. Another important finding was that adequately restored teeth had higher plaque and gingivitis scores and deeper pockets than unrestored teeth. Interestingly, the percent increase in gingivitis and pocket formation was greater between unrestored and adequately restored teeth than between adequately and inadequately restored teeth. This suggests that the major adverse effects to the gingiva and periodontium came from the initial restoration of teeth, even if performed adequately. It is also of interest that calculus scores were highest on unrestored compared with restored teeth. This was an unusual finding and to our knowledge had not been previously reported. Table II presents the data for single crowns. In general the differences between adequate and inadequate restorations were minimal. In contrast, adequately restored and unrestored teeth showed major differences in mean plaque levels, gingivitis scores, and pocket depths. The results for crown retainers are seen in Table III and were essentially the same. The data suggest that the major adverse effects on the periodontium came from the placement of a crown. Within the range of quality variation seen in this study, the differences between adequate and inadequate crowns were minimal. The results of the multiple stepwise regression is presented in Table IV for amalgam restorations with respect to gingival cavosurface margin quality. This analysis was done at the tooth surface level. It can be seen that compared with no restoration, both THE JOURNAL
OF PROSTHETIC
DENTISTRY
Table IV. Standardized
regression coefficients showing relative influence of quality of amalgam cavosurface margins on gingival scores and periodontal pocket depths Variable Adequate restoration Inadequate restoration Patient age Patient income Patient education Dental visits past 2 years Plaque score Calculus score
Gingival score
Pocket depth
,144) ,090’ -.038 ,038 -.005 -.074* .334t .129*
.169* ,115” .070* .003 .020 -.016 ,120’ ,190’
*p < .05. tp < .Ol.
an adequate and inadequate gingivai cavosurface margin had a significantly positive effect on gingivitis and periodontal pocket formation. Other variables that influenced gingivitis were plaque levels and the frequency of dental visits. Patient age was positively associated with pocket depth. This analysis generally confirmed the ANOVA previously discussed. It showed that plaque levels were of equal importance with the quality of the restoration itself to periodontal health. The positive association with dental visits may reflect removal of plaque and calculus, as well as the effect of patient education on proper oral hygiene practices. Table V shows a similar analysis at the level of the entire mouth, with the average quality and health 17
GRASS0
Table V. Standardized regression coefficients showing relative influence of several factors on average gingival index and periodontal pocket depths per subject* Variable Amalgam quality score Patient age Patient education Family income Dental visits past 2 years Plaque score
Gingival index ,006 .047 -.OOl .064 -.114t .674$
Pocket depth -.065 .31t ,021 -.016 -.042 .272t
*Quality score is based on the ratings of gingival cavosurface margins of amalgam restorations. t/l < .05. $/J < .ot.
indexes per patient. This table clearly demonstrates the importance of plaque as a determinant of gingivitis and the relative unimportance of restoration quality. Again, patients with more dental visits had lower gingivitis scores. In terms of pocket depth, Table V indicates that at the level of the entire mouth, age and plaque levels showed a positive and significant association with periodontal disease. Older patients with more plaque had deeper pockets. Average restoration quality had no apparent influence on average pocket depths nor did the other patient related variables. The regression analysis for single and retainer crowns was not presented here but showed essentially the same results.
DISCUSSION The findings of this study suggest that there is a relationship between the quality of restorative care and periodontal health. Teeth with inadequate restorations had significantly more plaque, gingivitis, and periodontal pocket formation than adequately restored teeth. Inadequacies in gingival cavosurface margins of amalgam restorations appear to have the most negative impact on the periodontium. As many investigators have shown, disruption of tooth surface integrity adjacent to gingival tissue increases plaque accumulations and in time inflammation. In contrast to amalgam restorations, the oral health response to crowns appears to relate mainly to inadequate embrasures and contours rather than to cavosurface margins. For both amalgam restorations and crowns, the health of the periodontium is adversely affected by the presence of a restoration. That is, even an adequately restored tooth leads to increased gingivitis and periodontal pocket formation. The multivariate analyses indicate that while both the
18
ET 41.
quality and presence of restorations are significant factors in gingivitis and periodontitis, the amount of plaque is even more important. In fact, considering the health status of the entire mouth rather than individual tooth surfaces alone, plaque accounted for almost all the explained variance. In contrast, restoration quality and selected patient characteristics accounted for a negligible amount of the remaining unexplained variation. There are several important clinical implications to be drawn from this study. 1. Contour of crowns and gingival cavosurface margins of amalgam restorations are important determinants of periodontal health and require the careful attention of dentists. 2. Restorations should be avoided if at all possible consistent with good treatment. This means that cariespreventive services such as topical fluorides and sealants should be stressed, and that teeth should only be restored when a carious lesion can he demonstrated unequivocally. 3. The more restorations placed in a patient’s mouth, the more adverse will be the effect on periodontal health, especially if restoration quality is inadequate. 4. The larger the number of restorations, the more important plaque control measures become in the control of periodontal health. Without effective plaque control, the quality of restorative care is relatively unimportant as a determinant of periodontal health. From a more general perspective, this study indicates that the most significant changes in periodontal health will be brought about by improving plaque control. Better restorations will help to achieve this goal, but improving restorative quality alone is unlikely to have a major effect on the health of the periodontium.
POLICY IMPLICATIONS The development of a national policy on restoration quality assurance requires knowledge of the magnitude of the problem and the association between restoration quality and oral health. As previously reported, it appears that most amalgam and composite resin restorations are of adequate quality.’ The primary concern is cast crown restoratons, in which nearly half are overcontoured. However, cast crowns are a relatively uncommon service.” Likewise 80% of inadequate amalgam restorations are concentrated in the 10% of the population that has six or more restored teeth.’ This means that most people do not have inadequate amalgam restorations or crowns, and would not be affected by a quality assurance program that focused on restoration quality. Of course, there is a small segment of the population that has many inadequately restored teeth. This is the group that has the potential for benefiting from an effective quality review system.
JANUARY
1985
VOLUME
53
NUMBER
1
RESTORATION
QUALITY
AND
PERIODONTAL
HEALTH
The relationship between the quality of restorations and periodontal health is critical. The question is, What increase in periodontal health can be expected if the quality of restorative care is improved? The findings from this study suggest that major improvements in periodontal health are not likely. While it is clear that inadequate restorative care causes more disease and that dentists should make every effort to avoid overhanging amalgam margins and overcontoured crowns, the quality of restorations does not account for much of the variance in periodontal health. Of far greater importance is the general level of plaque. Unless plaque is controlled, it is unlikely that any other strategy (for example, improved restoration quality) will have much effect on periodontal health. The data also suggest that adequately restored teeth are associated with a’ significant increase in gingivitis scores and pocket depths. Improvements in periodontal health will also require fewer restorations. Thus even if quality assurance programs could improve restorative quality, they are unlikely to lead to major improvements in the health status of the periodontium. Relatively few people have inadequately restored teeth; and the link between restoration quality and periodontal health, while statistically significant, is not particularly strong relative to other factors. It seems clear that to improve oral health, plaque levels and the number of restorations need to be reduced. Both of these require making patients more conscientious in their oral hygiene practices and more regular in attendance at dental offices. This study suggests that quality assurance programs that focus on restorative care cannot be expected to lead to substantial improvements in the population’s periodontal health. Rather, the findings indicate that plaque levels and the number of restored teeth are more important determinants of periodontal health. Thus, primary preventive programs may have the greatest potential for controlling periodontal disease. CONCLUSIONS This study investigated the quality of restorative care and its relationship to gingival and periodontal health. The results suggest that improvements in the quality of crowns and amalgam restorations are unlikely to lead to large gains in the health of the periodontium. Effective caries and plaque preventive programs are far more promising approaches. Fewer restored tooth surfaces, oral hygiene programs, and professional preventive services can be expected to reduce plaque accumulation, the primary cause of gingival and perindontal disease.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
REFERENCES 1. Grasso, J. E., Nalbandian, J., Sanford, C., and Bailit, H.: The quality of restorative dental care. J PROSTHETDENT 42571, 1979. 2. Waerhaug, J,: Tissue reaction around artificial crowns. J Periodontol 24~172, 1953. 3. Alexander, A. G.: Periodontal aspects of conservative dentistry. Br Dent J 125:111, 1968. 4. Bjorn, A. L., Bjorn, H., and Grkovic, B.: Marginal fit of restorations and its relation to periodontal bone level. Part I. Metal filings, Odont Revy 20~311, 1969. 5. Gilmore N., and Sheihan, A.: Overhanging dental restorations and periodontal disease. J Periodontol 428, 1971. 6. Rickter, W. A.: Relationship of crown margin placement to gingival inflammation. J PROSTHETDENT 30~156, 1973. 7. Leon, A. R.: Amalgam restoration and periodontal disease. Br Dent J 14:377, 1976. 8. Trott, J. R., and Sherkat, A.: Effect of Class II amalgam restorations on health of gingiva; A clinical survey. J Can Dent Assoc 30~766, 1964. 9. Silness, J.: Periodontal conditions in patients treated with dental bridges. Part I. J Periodont Res 5~60, 1970. 10. Silness, J.: Periodontal condition in patients treated with dental bridges. Part II. J Periodont Res 5:219, 1970. 11. Silness, J.: Periodontal conditions in patients treated with dental bridges. Part III. J Periodont Res 5:225, 1970. 12. Renggli, H. H., and Regolati, B.: Gingival inflammation and plaque accumulation by well-adapted supragingival and subgingival proximal restorations. Helv Odont Acta 16~99, 1972. 13. Parkinson, C. F.: Excessive crown contours facilitate endemic plaque niches. J PROSTHETDENT 35~424, 1976. 14. Bailit, H. L., Koslowsky, M., Grasso, J., Holaman, S.,Levine, R., Valluzzo, P., and Atwood, P.: Quality of dental care: I. Development of standards. J Am Dent Assoc 89:842, 1974. 15. Loe, H., and Silness, J.: Periodontal disease in pregnancy: I. Prevalence and severity. Acta Odontol Stand 21:533, 1963. 16. Silness, J., and Loe, H.: Periodontal disease in pregnancy: II. Correlation between oral hygiene and periodontal conditions. Acta Odontol Stand 22~121, 1964. 17. Ramfjord, S. P.: The periodontal disease index. J Periodontol 38:602, 1967. 18. National Center for Health Statistics: Basic Data on Dental Examination Findings of Persons l-74 years. DHEW Publication No. (PHS) 79-1662. Series 11, No. 214, Dept of Health, Education and Welfare, 1979, Hyattsville, Md. 19. Ten-State National Study-1968-1970. DHEW Publication No. (HSM) 72-8131, Dept. of Health, Education and Welfare, Center for Disease Control, 1972, Atlanta, Ga. 20. Bailit, H. L.: Effectiveness of personal dental services on improving oral health. J Pub1 Health Dent 38~289, 1978. 21. National Center for Health Statistics: Periodontal Disease in Adults. DHEW Publication No. (HRA) 74-1623, series II, No. 141. Dept. of Health, Education and Welfare, 1965, Rockville, Md. Reprint requests to: DR. JOSEPHE. GRASSO UNIVERSITYOF CONNECTICUT SCHOLLOF DENTAL MEDICINE FARMINGTON, CT 06032
19
displace it. The threads are also 1 mm apart, so 1 mm of dentin between each thread must be crushed before the post is loosened. This may require an inordinate amount of force. The Flexi-Post also has a wide-diameter, threaded, second tier that may be responsible for additional retention. It was noted in the second part of the study that as the size of the Flexi-Post increased, the magnitude of force required for dislodgment also increased. Because both the length and the diameter of the post increases as the post size increases, it is difficult to determine which dimension was more responsible for the increased retention of the post.
SUMMARY AND CONCLUSIONS
REFERENCES Guzy, G. E., and Nicholls, J. I.: In vitro comparison of intact endodontically treated teeth with and without endo-post reinforcement. J PROSTHET DENT 4!2:39, 1979. 2. Trabert, K. C., Caputo, A. A.. and Abou-Ross, M.: Tooth fracture-A comparison of endodontic and and restorative treatments. J Endodont 4~341, 1978. 3. Deutsch, A. S., Musikant, B. L., Cavallari, J., and Lepley, J. B.. Prefabricated dowels: A literature review. J PROSTHET DEKI 49~498, 1983. 4. Standlee, J. P., Caputo, A. A., and Hanson, E. C.: Retention ot endodontic dowels: Effects of cement, dowel length, diameter, and design. J PROSTHET DENT 39~401, 1978. 5. Standlee, J. P.. Caputo, A. A., Holcomb, J., and Trabert, K. C.: The retentive and stress-distributing properties of a threaded endodontic dowel. J PROSTHET DENT 44~398. 1980. 1.
Hepnnt requeststo:
Fifty Flexi-Posts were cemented in extracted teeth and tested for tensile strength. 1. The Flexi-Post was the most retentive post tested when compared with posts used in a similar study. 2. The retention of the Flexi-Post became greater as the size of the post increased.
DR. ALLAN S. DEUTSC:H 119 W. 57~~ ST., STE. 700 NEW YORK, NY 10019
Joseph E. Grasso, D.D.S., M.S.,* John NlhbPndian, D.M.D.,** Howard Bailit, D.M.D., Ph.D.‘**+ University
of Connecticut,
School of Dental
Medicine,
Collin Sanford, D.M*D.,***
and
Farmington, Conn.
T
he development of a dental quality assurance policy requires information on three basic issues: (1) the adequacy of dental care in the general population of dental patients, (2) the relationship between inadequate quality care and oral health, and (3) the relative importance of quality care compared with other factors that influence oral health. With this information, policy makers could determine the need for a formal quality assurance system, the form the system might take, and the improvements in oral health that could reasonably be achieved by such a system. In the first report of this series, Grasso et al.’ described the technical quality of restorative care in a sample of 291 adults. They reported that the quahty of Supported by Grant No. 336-75 from the University of Connecticut Research Foundation. *Professor, Department of Restorative Dentistry. **Professor, Department of Periodontology. ***Assistant Professor, Department of Restorative Dentistry. ****Professor, Department of Behavioral Sciences and Community Health. 14
ET AL
amalgam, composite resin, and cast restorations was relatively high for all categories. In contrast, individual crowns, retainers, and pontics were substantially less adequate. In this article, data from the same project are used to investigate the relationship between the quality of restorative dental care and periodontal health. Previous research in animals and humans indicates that (1) there is greater marginal inflammation associated with subgingival restorations when compared with supragingival restorations, (2) better fit and finish of the margins have a significant positive effect on gingival health, and (3) restored teeth are associated with greater inflammation than unrestored teeth.2”Z Other articles have shown that there is a relationship between plaque accumulation caused by inadequate restorations and periodontal disease.2~‘“. “. I3 Building on the previous report, the objectives of the present study were (1) to quantify the effects of inadequate restorations on the health of periodontal tissues, (2) to compare the relative importance of restoration quality with other factors that influence periodontal JANUARY
1985
VOLUME
53
NUMBER
1
RESTORATION QUALITY AND PERIODONTAL
Table I. Analysis
of variance
HEALTH
for amalgams* Gingival cavosurface margin
Plaque Inadequate Adequate No restoration Calculus Inadequate Adequate No restoration Gingivitis Inadequate Adequate No restoration Pocket depth Inadequate Adequate No restoration
Embrasures
Marginal
ridges
No.
x
No.
x
No.
x
414 1633 6126
1.20 1.05 1.05
302 1624 6247
1.15 1.07 1.05
240 1636 6297
1.18 1.07 1.05
412 1621 6137
.43 .33 .47
301 1611 6258
.41 .31 .47
239 1623 6308
.46 .30 .47
414 1633 6129
1.26 1.16 1.01
302 1624 6250
1.25 1.18 1.01
240 1636 6300
1.26 1.19 1.01
414 1632 6118
3.31 3.17 3.03
302 1623 6239
3.21 3.18 3.04
240 1635 6289
3.20 3.19 3.04
x = Mean of sample. *Effects of unrestored, adequately restored, and inadequately restored teeth on plaque, calculus, gingivitis, and pocket depths. Data on mesial and distal surfaces of molars and premolars are included. All ANOVA’s are statistically significant CI, < .Ol).
health, and (3) to consider the results of the study in the context of national policies on dental quality assurance systems. METHOD Notices were sent to all University of Connecticut Health Center employees (excluding students) to request their participation in the study. Three mailings resulted in the appearance of 291 people, a response rate of about 13%. For each subject, an assessment of the technical quality of individual tooth restorations, crowns and fixed partial dentures and oral health status was made.’ Examinations were performed with mirror, explorer, and Michigan probe (Hu Friedy, Chicago, Ill.), without the use of radiographs. Subjects also completed a questionnaire that provided information on their sociodemographic characteristics, use of dental services, oral hygiene practices, and attitudes and knowledge of dentistry. The technical quality of restorative and prosthetic services was assessedby explicit criteria developed and tested by Bailit et al. I4 The criteria relate to the following services: amalgam restorations, single crowns, retainers, and pontics. Each restoration is rated for several quality categories, such as occlusion and gingival cavosurface margins. Each category has explicit criteria that define adequate care. A category is scored adequate if ail criteria are met. An inadequate score is assigned when one or more criteria are not met. The percent of adequate scores can be averaged per criterion and per quality category or per tooth surface, restoration, and mouth. THE JOURNAL OF PROSTHETIC DENTISTRY
The oral health variables of interest, gingival inflammation and periodontal pocket depth, were measured with the gingivitis index of Liie and Silnessi5 and probing at six locations per tooth with a standardized technique. Plaque was measured by the method of Silness and L6e.16 Calculus was assessedby a modified Ramfjord calculus index.” All teeth except third molars were included in the study. Three faculty members from the University of Connecticut School of Dental Medicine participated in the examination of subjects. Each subject was examined by two participants; the oral health, plaque, and calculus data were first collected by one examiner and the restoration quality was assessedby the other examiner. All examiners were initially trained for 12 hours in the use of the indexes, during which time 25 subjects were each seen independently by pairs of examiners to determine inter-rater reliability. As noted in the previous article on this project, reliability levels were within acceptable limits.’ Two approaches were used to determine the relationship between oral health and the technical quality of care. First, analysis of variance (ANOVA) was used to compare the effects of no restoration, an adequate restoration, and an inadequate restoration on plaque accumulation, calculus deposits, gingivitis, and periodontal pocket depths. This was done for each of the following types of restorations: amalgam restorations with two or more surfaces, single crowns, and retainer crowns. The second approach involved the use of a multiple stepwise regression to relate quality variation to oral 15
GRASS0
Table II. Analysis of variance --___
for crowns*
Gingival cavosurface margins No. Plaque Inadequate Adequate No restoration Calculus Inadequate Adequate No restoration Gingivitis Inadequate Adequate No restoration Pocket depth Inadequate Adequate No restoration
ET Ai.
79 149 14,729 79 141 14,724
Embrasures x
.87 1.09 .99 ,139 ,092 s20
Marginal
ridges
No.
x
No.
x
219 542 29.497
.88 .81 .?I
2: 257 29,974
1.11
213 532 29.490
.34 .14 .40
27 251 29.957 L
79 149 14,732
1.35 1.36 .95
219 542 29,504
1.25 1.09 .75
79 149 14,719
3.31 3.19 2.77
219 542 29,486
2.73 2.67 2.19
i
I 01 .I-1
27 257 29,981 87 257 29,963
3.18 3.21 2.20
x = hlean of the sample. *Effects of unrestored, adequately restored, and inadequately restored teeth on plaque, calculus, gingivitis, and pocket depths. Data on mesial and distal surfaces of molars and premolars are included. All ANOVA’s are statistically significant (p < ,011.
health, with controls for several intervening variables. At issue was the relative importance of restoration quality to periodontal health compared with several patientrelated variables that are essentially beyond the control of the dentist. This analysis was undertaken at the level of the entire dentition and specific surfaces. The dentition analysis allowed investigation of the effects of quality variation on restored and unrestored teeth. The relevant question is whether poor quality restorations in some teeth lead to a general increase in gingivitis and pocket depths throughout the mouth. The analysis at the tooth surface level permitted determination of the association between an inadequately restored surface and gingivitis and pocket depth at that surface. The intervening variables in the multiple stepwise regression were patient age, education, family income, number of visits to the dentist in the past two years, plaque levels, and calculus scores. In terms of the predicted effect of the variables, patient age is associated with increasing periodontal disease, and hence pocket depth should increase in older patients.‘* Gingivitis is also positively related to age but to a lesser extent, especially in adults.” Patient education level measured in years of schooling is related to oral hygiene practices, which in turn influence gingivitis and periodontal disease.‘* Those with more years of education are expected to have less gingivitis and shallower pockets. Patient income is closely related to education and should have the same general effect. I8 Considered separately, education should have a greater effect than income.‘* 16
Number of visits to a dentist in the past two years provided an estimate of the subject’s use of dental services. Other studies have shown that people who receive periodic dental care have less plaque and gingivitis and fewer periodontal pockets.‘9,2”Plaque levels are closely and positively related to gingivitis and increased pocket depth. 21 The separate effects of calculus and periodontal pocket depths are not entirely clear, because both are closely associated with plaque accumulations. RESULTS Table I presents the ANOVA that compared plaque, calculus, gingivitis, and pocket depth scores for unrestored, adequately restored, and inadequately restored Class II amalgam restorations (molars and premolars). The data were available for three aspects of restoration quality: gingival cavosurface margins, embrasures, and marginal ridges. In general, the results indicated that among the three dimensions of amalgam quality, inadequate gingival cavosurface margins had the most negative effect on the health of the periodontium. However, there was a moderate association among quality ratings in the three dimensions of restoration quality (correlation coefficients of 0.4 to 0.6, p <.05). This means that restorations rated inadequate on one quality dimension tend to be rated inadequate for the others as well. Thus, it was difficult to determine their independent effects on periodontal health. Table I also indicates that the mean plaque, gingivitis, and pocket depth scores were highest for inadequate restorations. As with previous studies, poor quality restorations were associated with greater plaque accuJANUARY
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Table III. Analysis
AND
PERIODONTAL
of variance
HEALTH
for crown retainers*
Gingival cavosurface margins
Plaque Inadequate Adequate No restoration Calculus Inadequate Adequate No restoration Gingivitis Inadequate Adequate No restoration Pocket depth Inadequate Adequate No restoration
Marginal
Embrasures No.
x
.88 .81 .71
27 257 29,974
1.14 1 .Ol .71
213 532 29,490
.34 .I4 .40
27 251 29,957
.ll .I2 .39
1.44 1.08 .95
219 542 29,504
1.25 1.09 .75
27 257 29,981
1.44 1.33 .75
3.40 3.23 2.77
219 542 29,486
2.73 2.67 2.19
87 257 29,963
3.18 3.21 2.20
No.
R
No.
47 127 14,729
1.61 1.07 .99
219 542 29,497
47 127 14,724
.87 .I8 .52
47 127 14,732 47 127 14,719
x
ridges
X = Mean of the sample. *Effects of unrestored, adequately restored, and inadequately restored teeth on plaque, calculus, gingivitis, and pocket depths. Data on mesial and distal surfaces of molars and premolars are included. All ANOVA’s are statistically significant (,b < .Ol).
mulation and presumably in turn with more gingivitis and pocket development. Another important finding was that adequately restored teeth had higher plaque and gingivitis scores and deeper pockets than unrestored teeth. Interestingly, the percent increase in gingivitis and pocket formation was greater between unrestored and adequately restored teeth than between adequately and inadequately restored teeth. This suggests that the major adverse effects to the gingiva and periodontium came from the initial restoration of teeth, even if performed adequately. It is also of interest that calculus scores were highest on unrestored compared with restored teeth. This was an unusual finding and to our knowledge had not been previously reported. Table II presents the data for single crowns. In general the differences between adequate and inadequate restorations were minimal. In contrast, adequately restored and unrestored teeth showed major differences in mean plaque levels, gingivitis scores, and pocket depths. The results for crown retainers are seen in Table III and were essentially the same. The data suggest that the major adverse effects on the periodontium came from the placement of a crown. Within the range of quality variation seen in this study, the differences between adequate and inadequate crowns were minimal. The results of the multiple stepwise regression is presented in Table IV for amalgam restorations with respect to gingival cavosurface margin quality. This analysis was done at the tooth surface level. It can be seen that compared with no restoration, both THE JOURNAL
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Table IV. Standardized
regression coefficients showing relative influence of quality of amalgam cavosurface margins on gingival scores and periodontal pocket depths Variable Adequate restoration Inadequate restoration Patient age Patient income Patient education Dental visits past 2 years Plaque score Calculus score
Gingival score
Pocket depth
,144) ,090’ -.038 ,038 -.005 -.074* .334t .129*
.169* ,115” .070* .003 .020 -.016 ,120’ ,190’
*p < .05. tp < .Ol.
an adequate and inadequate gingivai cavosurface margin had a significantly positive effect on gingivitis and periodontal pocket formation. Other variables that influenced gingivitis were plaque levels and the frequency of dental visits. Patient age was positively associated with pocket depth. This analysis generally confirmed the ANOVA previously discussed. It showed that plaque levels were of equal importance with the quality of the restoration itself to periodontal health. The positive association with dental visits may reflect removal of plaque and calculus, as well as the effect of patient education on proper oral hygiene practices. Table V shows a similar analysis at the level of the entire mouth, with the average quality and health 17
GRASS0
Table V. Standardized regression coefficients showing relative influence of several factors on average gingival index and periodontal pocket depths per subject* Variable Amalgam quality score Patient age Patient education Family income Dental visits past 2 years Plaque score
Gingival index ,006 .047 -.OOl .064 -.114t .674$
Pocket depth -.065 .31t ,021 -.016 -.042 .272t
*Quality score is based on the ratings of gingival cavosurface margins of amalgam restorations. t/l < .05. $/J < .ot.
indexes per patient. This table clearly demonstrates the importance of plaque as a determinant of gingivitis and the relative unimportance of restoration quality. Again, patients with more dental visits had lower gingivitis scores. In terms of pocket depth, Table V indicates that at the level of the entire mouth, age and plaque levels showed a positive and significant association with periodontal disease. Older patients with more plaque had deeper pockets. Average restoration quality had no apparent influence on average pocket depths nor did the other patient related variables. The regression analysis for single and retainer crowns was not presented here but showed essentially the same results.
DISCUSSION The findings of this study suggest that there is a relationship between the quality of restorative care and periodontal health. Teeth with inadequate restorations had significantly more plaque, gingivitis, and periodontal pocket formation than adequately restored teeth. Inadequacies in gingival cavosurface margins of amalgam restorations appear to have the most negative impact on the periodontium. As many investigators have shown, disruption of tooth surface integrity adjacent to gingival tissue increases plaque accumulations and in time inflammation. In contrast to amalgam restorations, the oral health response to crowns appears to relate mainly to inadequate embrasures and contours rather than to cavosurface margins. For both amalgam restorations and crowns, the health of the periodontium is adversely affected by the presence of a restoration. That is, even an adequately restored tooth leads to increased gingivitis and periodontal pocket formation. The multivariate analyses indicate that while both the
18
ET 41.
quality and presence of restorations are significant factors in gingivitis and periodontitis, the amount of plaque is even more important. In fact, considering the health status of the entire mouth rather than individual tooth surfaces alone, plaque accounted for almost all the explained variance. In contrast, restoration quality and selected patient characteristics accounted for a negligible amount of the remaining unexplained variation. There are several important clinical implications to be drawn from this study. 1. Contour of crowns and gingival cavosurface margins of amalgam restorations are important determinants of periodontal health and require the careful attention of dentists. 2. Restorations should be avoided if at all possible consistent with good treatment. This means that cariespreventive services such as topical fluorides and sealants should be stressed, and that teeth should only be restored when a carious lesion can he demonstrated unequivocally. 3. The more restorations placed in a patient’s mouth, the more adverse will be the effect on periodontal health, especially if restoration quality is inadequate. 4. The larger the number of restorations, the more important plaque control measures become in the control of periodontal health. Without effective plaque control, the quality of restorative care is relatively unimportant as a determinant of periodontal health. From a more general perspective, this study indicates that the most significant changes in periodontal health will be brought about by improving plaque control. Better restorations will help to achieve this goal, but improving restorative quality alone is unlikely to have a major effect on the health of the periodontium.
POLICY IMPLICATIONS The development of a national policy on restoration quality assurance requires knowledge of the magnitude of the problem and the association between restoration quality and oral health. As previously reported, it appears that most amalgam and composite resin restorations are of adequate quality.’ The primary concern is cast crown restoratons, in which nearly half are overcontoured. However, cast crowns are a relatively uncommon service.” Likewise 80% of inadequate amalgam restorations are concentrated in the 10% of the population that has six or more restored teeth.’ This means that most people do not have inadequate amalgam restorations or crowns, and would not be affected by a quality assurance program that focused on restoration quality. Of course, there is a small segment of the population that has many inadequately restored teeth. This is the group that has the potential for benefiting from an effective quality review system.
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RESTORATION
QUALITY
AND
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HEALTH
The relationship between the quality of restorations and periodontal health is critical. The question is, What increase in periodontal health can be expected if the quality of restorative care is improved? The findings from this study suggest that major improvements in periodontal health are not likely. While it is clear that inadequate restorative care causes more disease and that dentists should make every effort to avoid overhanging amalgam margins and overcontoured crowns, the quality of restorations does not account for much of the variance in periodontal health. Of far greater importance is the general level of plaque. Unless plaque is controlled, it is unlikely that any other strategy (for example, improved restoration quality) will have much effect on periodontal health. The data also suggest that adequately restored teeth are associated with a’ significant increase in gingivitis scores and pocket depths. Improvements in periodontal health will also require fewer restorations. Thus even if quality assurance programs could improve restorative quality, they are unlikely to lead to major improvements in the health status of the periodontium. Relatively few people have inadequately restored teeth; and the link between restoration quality and periodontal health, while statistically significant, is not particularly strong relative to other factors. It seems clear that to improve oral health, plaque levels and the number of restorations need to be reduced. Both of these require making patients more conscientious in their oral hygiene practices and more regular in attendance at dental offices. This study suggests that quality assurance programs that focus on restorative care cannot be expected to lead to substantial improvements in the population’s periodontal health. Rather, the findings indicate that plaque levels and the number of restored teeth are more important determinants of periodontal health. Thus, primary preventive programs may have the greatest potential for controlling periodontal disease. CONCLUSIONS This study investigated the quality of restorative care and its relationship to gingival and periodontal health. The results suggest that improvements in the quality of crowns and amalgam restorations are unlikely to lead to large gains in the health of the periodontium. Effective caries and plaque preventive programs are far more promising approaches. Fewer restored tooth surfaces, oral hygiene programs, and professional preventive services can be expected to reduce plaque accumulation, the primary cause of gingival and perindontal disease.
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REFERENCES 1. Grasso, J. E., Nalbandian, J., Sanford, C., and Bailit, H.: The quality of restorative dental care. J PROSTHETDENT 42571, 1979. 2. Waerhaug, J,: Tissue reaction around artificial crowns. J Periodontol 24~172, 1953. 3. Alexander, A. G.: Periodontal aspects of conservative dentistry. Br Dent J 125:111, 1968. 4. Bjorn, A. L., Bjorn, H., and Grkovic, B.: Marginal fit of restorations and its relation to periodontal bone level. Part I. Metal filings, Odont Revy 20~311, 1969. 5. Gilmore N., and Sheihan, A.: Overhanging dental restorations and periodontal disease. J Periodontol 428, 1971. 6. Rickter, W. A.: Relationship of crown margin placement to gingival inflammation. J PROSTHETDENT 30~156, 1973. 7. Leon, A. R.: Amalgam restoration and periodontal disease. Br Dent J 14:377, 1976. 8. Trott, J. R., and Sherkat, A.: Effect of Class II amalgam restorations on health of gingiva; A clinical survey. J Can Dent Assoc 30~766, 1964. 9. Silness, J.: Periodontal conditions in patients treated with dental bridges. Part I. J Periodont Res 5~60, 1970. 10. Silness, J.: Periodontal condition in patients treated with dental bridges. Part II. J Periodont Res 5:219, 1970. 11. Silness, J.: Periodontal conditions in patients treated with dental bridges. Part III. J Periodont Res 5:225, 1970. 12. Renggli, H. H., and Regolati, B.: Gingival inflammation and plaque accumulation by well-adapted supragingival and subgingival proximal restorations. Helv Odont Acta 16~99, 1972. 13. Parkinson, C. F.: Excessive crown contours facilitate endemic plaque niches. J PROSTHETDENT 35~424, 1976. 14. Bailit, H. L., Koslowsky, M., Grasso, J., Holaman, S.,Levine, R., Valluzzo, P., and Atwood, P.: Quality of dental care: I. Development of standards. J Am Dent Assoc 89:842, 1974. 15. Loe, H., and Silness, J.: Periodontal disease in pregnancy: I. Prevalence and severity. Acta Odontol Stand 21:533, 1963. 16. Silness, J., and Loe, H.: Periodontal disease in pregnancy: II. Correlation between oral hygiene and periodontal conditions. Acta Odontol Stand 22~121, 1964. 17. Ramfjord, S. P.: The periodontal disease index. J Periodontol 38:602, 1967. 18. National Center for Health Statistics: Basic Data on Dental Examination Findings of Persons l-74 years. DHEW Publication No. (PHS) 79-1662. Series 11, No. 214, Dept of Health, Education and Welfare, 1979, Hyattsville, Md. 19. Ten-State National Study-1968-1970. DHEW Publication No. (HSM) 72-8131, Dept. of Health, Education and Welfare, Center for Disease Control, 1972, Atlanta, Ga. 20. Bailit, H. L.: Effectiveness of personal dental services on improving oral health. J Pub1 Health Dent 38~289, 1978. 21. National Center for Health Statistics: Periodontal Disease in Adults. DHEW Publication No. (HRA) 74-1623, series II, No. 141. Dept. of Health, Education and Welfare, 1965, Rockville, Md. Reprint requests to: DR. JOSEPHE. GRASSO UNIVERSITYOF CONNECTICUT SCHOLLOF DENTAL MEDICINE FARMINGTON, CT 06032
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