Fixed partial compromised Martin James University Kentucky, Dentistry,
dentures teeth
A. Freilich, D.D.S.,* G. Keagle, D.D.S.,***
supported
by periodontally
Larry C. Breeding, D.M.D., M.S.Ed.,** and Jerry J. G&nick, D.D.S., M.S.****
of Connecticut, School of Dental College of Dentistry, Lexington, Augusta, Ga.
Medicine, Farmington, Conn., University of Ky., and Medical College of Georgia, School of
This study tested the effect of fixed partial dentures on hypermobile abutment teeth with substantially reduced levels of periodontal attachment. One abutment tooth and one control (nonabutment) tooth of the same type and periodontal condition were selected for study in adults. Treatment consisted of periodontal therapy and a 3- or 4-unit fixed partial denture, after which all subjects were placed on a quarterly maintenance schedule. No differences were found between the mean baseline and 24-month measures for all dependent variables at test or control sites. (J PROSTHET D~~~1991;65:007-11.)
w*
lth both the life expectancy and retention of the dentition increasing for the general population, dentists will undoubtedly be called upon to treat mobile, periodontally compromisedteeth. These teeth are often located adjacent to edentulous spaces,soit is logical to test the abilities of thesecompromisedteeth to serveasabutment teeth for a fixed partial denture (FPD). There ispresently evidencefrom both animal and human retrospective studies indicating that periodontally compromised teeth can be suitable abutment teeth. Studies made with different animal modelshave shownthat there wasno increasein probing depth or lossof periodontal attachment when additional occlusal load was applied to mobile, well maintained teeth with reduced periodontal support.1-4 Swedish researchhas demonstrated that treated abutment teeth exhibiting substantial lossof periodontal support can successfullysupport an FPD in humansfor prolonged periods.5-10These retrospective reports compared abutment teeth supporting prosthesesof various designs
Presented at the American Association for Dental Research meeting, San Francisco, Calif. This study was partially funded by the Medical College of Georgia Biomedical Research Grant No. SO7-RR05795. *Assistant Professor, Prosthodontics, University of Connecticut, School of Dental Medicine. **Associate Professor, Prosthodontics, University of Kentucky, College of Dentistry. ***Associate Professor, Periodontics, Medical College of Georgia, School of Dentistry. ****Professor, Periodontics, Medical College of Georgia, School of Dentistry.
10/l/24060
THEJOURNALOF
PROSTHETIC
DENTISTRY
with similar nonabutment teeth in a different group of patients. Thesefindings, together with other clinical investigations, have shown that plaque control accomplished through personal oral hygiene, periodontal therapy, and consistent professionalmaintenance generally prevented further deterioration of the periodontium.l’-l4 Despite these studies, dentists continue to avoid using periodontally compromisedteeth asabutment teeth for an FPD. Many authors have indicated that abutment teeth for an FPD should possessstability and be “favorably” distributed in the dental arch with “acceptable” crown/ root ratios satisfying Ante’s law.15-lgThese authors have inferred that periodontally compromisedabutment teeth are unsuitable becausethey can be “overstressed” from the additional forces applied to the teeth supporting an FPD. A prospective clinical trial wasconducted to corroborate the retrospective evidence gathered by the Swedish researchers.Specifically, this study compared the probing attachment levels of hypermobile, periodontally compromised abutment teeth supporting a unilateral FPD with levelsin similarly involved nonabutment teeth in the same subject.
MATERIAL
AND
METHODS
The experimental designof the study is illustrated in Fig. To participate in this study, a subject was required to meet specificinitial eligibility criteria. A standardized protocol of dental treatments wasthen administered that enabledthesesubjectsto meet predetermined final eligibility criteria. After a baselineexamination of the periodontium adjacent to the study teeth, the subjectswere reexamined yearly for 2 years. 1.
607
FREILICH
Final Eligibility Criteria Met
Initial Eligibility Criteria Met
Operative Dentistry, Periodontal Therapy, Caries Control
ET AL
Fixed Prosthodontic Treatment, Periodontal Maintenance (2 week intervals for 3 months)
I I
Continued Maintenance irbvals)
Periodontal (3 month
I
Year 0 Exam
Year 1 Exam
Year 2 Exam
I
Data Collection Fig.
Selection
1. Flow chart of study design.
of patients
Twelve healthy adults whosecondition wasdiagnosedas generalizedsevereperiodontitis were selectedfrom a group of patients scheduledfor dental treatment at the Medical Collegeof Georgia,School of Dentistry. To meet the initial criteria of eligibility for this study, eachsubject neededto possess one potential experimental, or abutment tooth, and one control, or nonabutment tooth. This control tooth was the analogoustooth on the contralateral side of the same arch or the opposingarch. The experimental tooth waslocated adjacent to a nonterminal edentulous spaceor to a hopelesslyinvolved tooth requiring extraction. The control tooth waspart of an intact quadrant and wastherefore not located adjacent to a nonterminal edentulous space.All experimental and control teeth satisfiedthe initial eligibility criteria: (1) a minimum of 50% lossof periodontal attachment, asconfirmed by clinical and radiographic examination; (2) presenceof initial probing depths of 5 mm at a minimum of one site adjacent to the study tooth; (3) a tooth mobility of type 2 or 320;and (4) a minimum of 3 mm of osseoussupport, as determined by long-coneperiapical radiographs. The investigation wasexplained to the prospective subjects and informed consentwasobtained. Each subject involved with the study wasawardedan incentive for participation. Nine of the 12 subjectswho entered this study received the necessarydental treatment and were available for the recall and data collection visits. These nine adult subjects,ranging in agefrom 35 to 69years, wereevaluated for a period of 2 years. Two of the three nonparticipants withdrew prior to the completion of periodontal therapy, while one nonparticipant relocated.
Treatment
rendered
After screening was performed and informed consent wasobtained, the subjectsunderwent a similar protocol of
608
dental treatment. This treatment included plaque control instruction with reinforcement, the extraction of hopeless teeth, cariescontrol, periodontal therapy, and fixed prosthodontics. Periodontal therapy consistedof scalingand root planing, followed by surgical pocket reduction at study sites where probing depths remained greater than 4 mm upon reevaluation. Where study teeth were sufficiently mobile to interfere with function, occlusaladjustment, in addition to the removal of local fators, renderedtheseteeth stable for comfortable function. Upon each patient’s completion of active periodontal therapy, a maintenance program of professional plaque control was scheduled every 2 weeks for 3 months,21 followed by a recall scaling/prophylaxis every 3 months. The fixed prosthodontic phaseof treatment began 3 to 6 months after completion of the active periodontal therapy phaseupon attainment of predeterminedperiodontal goals adjacent to the study teeth. The predetermined goalsbecame the final periodontal eligibility criteria that were met prior to the baselineexamination. These were: plaque index (PlI) (Silnessand Liie22)and gingival index (GI) (LBe and Silness23)scoresless than or equal to 0.5; probing depths of lessthan or equal to 4 mm; no bleeding upon probing; and no furcation involvements exceedinggrade I. In addition, eachsubject’soverall PI1 and GI scoresrepresentedby the six Ramfjord teeth24satisfied scoresof 0.5 or less.Fixed prosthodontic treatment consistedof the placement of a three- or four-unit FPD supported by two abutment teeth, onepreviously designatedasthe experimental tooth. The FPDs were constructed with high noble nonceramic alloys and were veneeredwith Isosit (Williams Dental Company, Inc., Buffalo, N.Y.), a steam-curedcomposite resin. The FPDs were assembledintraorally, then presolderedbefore the addition of the veneer. All FPD retainers were madewith supragingival marginsto simplify maintenanceand to serve as a fixed reference for measur-
MAY
1991
VOLUME
96
NUMBER
6
FPDs
AND
PERIODONTALLY
COMPROMISED
TEETH
I. Mean probing attachment levels (7 SD.) at 54 abutment and 54 nonabutment sites for nine subjects at baseline and at 2-year examinations
Table
Abutment Nonabutment
Baseline exam
Two-year exam
4 2 1.3* 521
3.8 5x 1.3 5.2 k 0.9
II. Mean probing depth ( t S.D.) at 54 abutment and 54 nonabutment sites for nine subjects at baseline and at 2-year examinations
Table
Baseline
Change over a-year period + 0.24 - 0.22
Abutment Nonabutment
exam
1.6 -t 0.2* 1.6 t 0.3
Two-year
exam
1.6 + 0.4 1.7 k 0.6
*All values in millimeters.
*All values in millimeters. Table
ing probing attachment levels during the data collection examinations. After placement of the FPD, the subject satisfied the final eligibility criteria and qualified for the baseline examination.
Collection
of data
The periodontium was assessed at six sites adjacent to the experimental and control teeth in each subject at baseline and at the l- and 2-year postinsertion examinations. These assessments were made by measuring attachment levels and probing depths to the nearest millimeter and noting bleeding upon probing to the sulcular base. This examination was accomplished using a 0.70 mm diameter probe tip with Williams markings and a standardized force of 20 gm (Vine Valley Research, Middlesex, N.Y.). Probing attachment levels were measured by using the cementoenamel junction or the retainer margin as a fixed apicocoronal reference to the base of the clinical sulcus. In addition, the PlI and GI scores were recorded at the test sites and at four sites surrounding the six Ramfjord teeth. All measurements were completed by the same examiner and calibrations were made before data collection to attain an acceptable intraexaminer variation.25 The calibration exercises were performed on patients exhibiting similar periodontal disease and restorations who were not included in this study.
Data
analysis
The data were recorded on a computer-ready data collection form, keypunched, and verified. Statistical comparisons were made between the abutment and nonabutment teeth, and between the baseline and a-year measurements. Paired t tests were performed on the attachment level and probing depth measurements and Wilcoxon matched pairs signed-ranks tests were computed for the nonparametric data (PlI, GI, and bleeding upon probing).
RESULTS The mean interval between recall prophylaxis visits from the baseline to the 2-year examination was 4.5 f 2.7 months. Analysis of the 2-year data (n = 9 subjects) was not statistically significant. Clinical differences were also not evident between abutment and nonabutment teeth for probing attachment level, probing depth, bleeding upon
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
III.
Mean plaque and gingival indices (PI1 and
W Baseline
Abutment
exam
Two-year
exam
teeth
PI1 GI Nonabutment PI1 GI
0.15 + 0.19* 0.10 + 0.15
0.37 + 0.31 0.13 f 0.27
0.19 If: 0.14 0.08 * 0.13
0.46 + 0.38 0.28 k 0.35
teeth
*All values in millimeters
probing, and PI1 and GI scores. Statistical differences were not detected between the abutment and nonabutment teeth when the proximal surfaces or facial/lingual surfaces were compared separately. Also, no statistical differences were found between the baseline and a-year measurements for all dependent variables at both abutment and nonabutment teeth. The mean probing attachment level measurements are listed in Table I. After 2 years, there was a mean gain of 0.24 mm for abutment sites and a mean loss of 0.22 mm for nonabutment sites. The mean probing depths for the abutment and nonabutment sites after 2 years were 1.6 + 0.4 and 1.7 & 0.6 mm, respectively (Table II). Six percent of abutment sites bled upon probing after 2 years, compared with 7% of nonabutment sites. There was no bleeding upon probing scored at either the abutment or nonabutment sites at the baseline examination. Mean PlI and GI scores are presented in Table III. The relatively low 2-year PlI and GI scores indicated continued patient compliance with respect to personal oral hygiene. Although no statistical differences were noted for these two variables, there was a trend for higher plaque and gingivitis scores over time.
DISCUSSION The data in this study revealed no statistical or clinically important differences between experimental and control teeth with respect to probing attachment levels or other periodontal parameters. Further, there were no detectable changes in probing attachment levels and probing depths measured at 2 years compared with baseline measures for abutment and nonabutment teeth. The mobile, periodontally compromised experimental and control teeth exhib-
609
FREILICH
ited “stable” probing attachment levels and continued function without discomfort after 2 years. There was no indication that unilateral FPDs without cross arch bracing were detrimental to the supporting periodontium. The small sample size in this study limited the power to detect statistically significant differences. However, the degree of similarity between the abutment and nonabutment sites supported the contention that there were no clinical differences. Before universal application of these findings to the general population, it would be appropriate to retest this study hypothesis with a larger number of subjects. The Swedish reports91 lo, 13*I4 demonstrated that unilateral FPDs were as successful as the cross arch bilateral FPDs for periodontal stability. However, the results they reported continue to be associated with the cross arch stabilization available from extensive multiunit bilateral FPDs with a bilaterally balanced occlusion. The abutment teeth in this study supported only three- to four-unit unilateral FPDs without cross arch bracing. The retention of these periodontally compromised teeth is noteworthy, but their prognosis remains guarded because of the levels of periodontal support. Furthermore, the optimism regarding successful results should be tempered by the limitations of a a-year study and the number of subjects. Earlier studies, 11-14however have previously indicated that the successful long-term maintenance of probing attachment levels at sites susceptible to periodontitis is largely a function of meticulous maintenance by the patient and dentist.
CLINICAL
IMPLICATIONS
OF RESULTS
It is recommended that periodontally compromised, mobile abutment teeth be considered to support FPDs under the following conditions: (1) when there is a lack of other favorably distributed abutment teeth with greater levels of periodontal support; (2) for a carefully selected patient with advanced loss of periodontal support who requires tooth replacement and who has a strong desire to retain the existing dentition; (3) when the patient and dentist are committed to a fastidious plaque control program; (4) when there is a recognition of the guarded prognosis associated with an FPD supported by periodontally compromised teeth because of the higher incidence of tooth fracture2‘j and pulpal problems27; and (5) when there is an awareness of the technical difficulties and prosthodontic failure associated with the management of poorly supported, mobile abutment teeth. With all the factors considered, the use of periodontally compromised abutment teeth to support a unilateral FPD for a highly motivated patient may be the best treatment alternative to an extensive fixed or removable prosthesis. This study concluded that with careful patient selection and good patient oral hygiene, hypermobile, periodontally compromised abutment teeth can support a unilateral FPD comfortably for 2 years. 610
ET AL
SUMMARY This study tested the effect of FPDs on hypermobile abutment teeth with substantially reduced periodontal support. One abutment and one control (nonabutment) tooth of the same type and periodontal condition were selected for study in adult subjects. The treatment consisted of periodontal therapy, placement of a three- and four-unit FPD, and active participation in a 3-month maintenance schedule. The 2-year data (n = 9 subjects) revealed no statistically significant differences (at p < 0.01) between test and control sites for mean probing attachment levels, probing depths, bleeding upon probing, and PI1 and GI scores. No differences were revealed between the mean baseline and 24-month measures for these dependent variables at test and control sites. At 2 years the mean probing depths for test and control sites were 1.64 + 0.44 and 1.74 + 0.60 mm, respectively.
REFERENCES 1. Bhaskar SN, Orban B. Experimental occlusal trauma. J Periodontol 1955;26:2’70-84. 2. Svanberg G. Influence of trauma from occlusion on the periodontium of dogs with normal or inflamed gingivae. Odontol Rev 1974;25:165-78. 3. Poison AM, Meitner SW, Zander HA. Trauma and progression of marginal periodontitis in squirrel monkeys. III. Adpatation of interproximal alveolar bone to repetitive injury. J Periodont Res 1976;11:279-89. 4. Ericsson I, Lindhe 3. Lack of effect of trauma from occlusion on the recurrence of experimental periodontitis. J Clin Periodontol1977;4:115n”
IL,.
5. Nyman S, Lindhe J, Lundgren D. The role of occlusion for the stability of fixed bridges in patients with reduced periodontal tissue support. J Clin Periodontol 1975;2:53-6. 6. Lundgren D, Nyman S, Heijl L, Carlsson FE. Functional analysis of fixed bridges on abutment teeth with reduced periodontal support. J Oral Rehabil 1975;2:105-16. 7. Nyman S, Lindhe J. Persistent tooth hypermobility following completion of periodontal treatment. J Clin Periodontol 1976881-93. 8. Nyman S, Lindhe J. Considerations on the design of occlusion in prosthetic rehabilitation of patients with advanced periodontal disease. J Clin Periodontol 1977;4:1-15. 9. Nyman S, Lindhe J. A longitudinal study of combined periodontal and prosthetic treatment of patients with advanced periodontal disease. J Periodontol 1979;50:163-9. 10. Nyman S, Ericsson I. The capacity of reduced periodontal tissues to support fixed bridge work. J Clin Periodontol 1982;9:469-14. 11. Suomi JD, Greene JC, Vermillion JR, Doyle J, Chang JJ, Leatherwood C. The effect of controlled oral hygiene procedures on the progression of periodontal disease in adults: results after third and final year. J Periodontol 1971;42152-60. 12. Ramfjord SP, Knowles JW, Nissle RR, Shick RA, Burgett FG. Longitudinal study of periodontal therapy. J Periodontol 1973;44:66-77. 13. Lindhe J, Nyman S. The effect of plaque control and surgical pocket elimination on the establishment and maintenance of periodontal health. A longitudinal study of periodontal therapy in cases of advanced periodontal disease. J Clin Periodontol 1975;2:67-79. 14. Axelsson P, Lindhe J. The significance of maintenance care in the treatment of periodontal disease. J Clin Periodontol 1981;8:281-94. 15. Ante IH. The fundamental principles of abutments. Mich State Dent Sot Bull 1926;8:14. 16. Reynolds MJ. Abutment selection for fixed prosthodontics. J PROSTHET DENT 1968;19:483-8. 1’7. Johnston JF, Phillips RW, Dykema RW. Modern practice in crown and bridge prosthodontice. 3rd ed. Philadelphia: WB Saunders Co, 1971. 18. Tylman SD, Malone WFP. Theory and practice of fixed prosthodontics. 7th ed. St Louis: CV Mosby Co, 1978.
MAY
19!31
VOLUME
65
NUMBER
5
FPDsANDPERIODONTALLYCOMPROMISEDTEETH
26. Lindhe J. Textbook of clinical periodontology. Copenhagen, Denmark: Munksgaard Publishing Co, 1984. 27. Langeland K, Rodriques H, Dowden W. Periodontal disease bacteria and pulpal histopathology. Oral Surg 1974;37:257-70.
19. Dykems RW, Goodacre CJ, Phillips RW. Johnston’s modern practice in fixed prosthodontics. 4th ed. Philadelphia: WB Saunders Co, 1986. 20. Miller SC. Textbook in periodontia. Philadelphia: Blakiston Division/ McGraw-Hill Book Co, 1950. 21. Lindhe J, Nyman S, Westfelt E. Critical probing depths in periodontal therapy. J Clin Periodontol 1982;9:323-36. 22. Silneas J, L6e H. Periodontal disease in pregnancy. II. Correlation between oral hygiene and periodontal condition. Acta Odontol Stand 1964;22:121-35. 23. L6e H, Silness J. Periodontal disease in pregnancy. I. Prevalence and severity. Acta Odontol Stand 1963;21:532-51. 24. Ramfjord SP. Indices for prevalence and incidence of periodontal disease. J Periodontol 1959;30:51-9. 25. Smith LW, Suomi JD, Greene JC, et al. A study of intra-examiner variation in scoring oral hygiene status, gingivai infiammation and epithelial attachment level. J Periodontol 1970;41:671-4.
Effect of metal characteristics Donald M. Belles, E. S. Duke, D.D.S., University
of Texas
Reprint requeststo: DR. MARTIN
A. FREILICH SCHOOL OF DENTAL. MEDICINE UNIVERSITY OF CONNECTICUT FARMINGTON, CT 06032
HEALTH
CENTER
Contributing author Ralph V. Katz, D.M.D., Ph.D., Associate Professor, Behavioral Sciences and Community Health, University of Connecticut, School of Dental Medicine, Farmington, Conn.
design and technique on the marginal of the collarless metal ceramic restoration D.D.S., M.S.,* M.S.D.***
Health
Science
Center,
Robert Dental
J. Cronin, School,
Jr., D.D.S.,**
San Antonio,
and
Tex.
This investigation examined the marginal characteristics of the collarless metal ceramic restoration made with two commonly used direct-lift techniques: (1) a porcelain/wax paste and (2) a porcelain/liquid slurry. The metal copings touched the shoulder in half of the groups and were left 0.6 mm short in the other half to comprise the four experimental groups. Marginal seal was evaluated at facial and lingual surfaces on embedded and sectioned specimens for each group. Photo negatives were made of each specimen and projected at a constant magnillcation so that tracings could be made of the space between the die shoulder and corresponding porcelain. Composite surface measurements were made for each sample with a Zeiss Interactive Digital Analysis System instrument to evaluate porcelain adaptation to the shoulder. The porcelainfliquid groups demonstrated significantly smaller (p 5 0.05) facial marginal openings than the porcelain/wax groups. The group made with the porcelain/liquid technique with the metal on the die shoulder produced the most consistent overall results. The porcelain/liquid group with the metal off the shoulder had a statistically larger (p 5 0.05) mean marginal opening from the external margin to a point 0.75 mm to the interior than both techniques with the metal on the shoulder. Lingual marginal adaptation did not vary with each of the four experimental groups. (J PROSTHET DENT 1991;65:61 l-9.)
The opinions contained in this article are those of the authors end are not to be construed as official or as reflecting the views of the United States Air Force or the Department of Defense. Based on a thesis submitted to the graduate faculty, University of Texas, Graduate School of Biomedical Sciences, San Antonio, Tex., in partial fulfillment of the requirements for the Master of
Science degree. Third place, American College of Prosthodontists, John J. Sharry Research Award Competition, Charleston, SC. *Lieutenant Colonel, U.S. Air Force, DC; Assistant Director, Area Dental Laboratory, USAF Clinic Kadene/SGDL, APO San
Francisco. **Colonel, U.S. Air Force, DC; Chairman, Department of Prosthodontics, Wilford Hell Medical Center, San Antonio, Tex. ***Associate Professor, Department of Restorative Dentistry.
10/l/27304
THEJOURNALOFPROSTHETICDENTISTRY
T
he esthetic demand in the region of the labial margin combined with the strength of conventional metal ceramic restorations may explain the increasing popularity of the collarless metal ceramic restoration.’ To simplify these restorations, several techniques have evolved over the years.2-5 A technique introduced by Prince et a1.6 used wax as a binder for the porcelain powder. The use of a wax suspension allows a more consistent separation of condensed porcelain from the die material. It also enhances flowing wax and porcelain into the small marginal gap that results from shrinkage in the original firing. Shrader et al.’ found 11.4% less shrinkage with the porcelain/wax method than with the conventional porcelain/
611
dentures teeth
A. Freilich, D.D.S.,* G. Keagle, D.D.S.,***
supported
by periodontally
Larry C. Breeding, D.M.D., M.S.Ed.,** and Jerry J. G&nick, D.D.S., M.S.****
of Connecticut, School of Dental College of Dentistry, Lexington, Augusta, Ga.
Medicine, Farmington, Conn., University of Ky., and Medical College of Georgia, School of
This study tested the effect of fixed partial dentures on hypermobile abutment teeth with substantially reduced levels of periodontal attachment. One abutment tooth and one control (nonabutment) tooth of the same type and periodontal condition were selected for study in adults. Treatment consisted of periodontal therapy and a 3- or 4-unit fixed partial denture, after which all subjects were placed on a quarterly maintenance schedule. No differences were found between the mean baseline and 24-month measures for all dependent variables at test or control sites. (J PROSTHET D~~~1991;65:007-11.)
w*
lth both the life expectancy and retention of the dentition increasing for the general population, dentists will undoubtedly be called upon to treat mobile, periodontally compromisedteeth. These teeth are often located adjacent to edentulous spaces,soit is logical to test the abilities of thesecompromisedteeth to serveasabutment teeth for a fixed partial denture (FPD). There ispresently evidencefrom both animal and human retrospective studies indicating that periodontally compromised teeth can be suitable abutment teeth. Studies made with different animal modelshave shownthat there wasno increasein probing depth or lossof periodontal attachment when additional occlusal load was applied to mobile, well maintained teeth with reduced periodontal support.1-4 Swedish researchhas demonstrated that treated abutment teeth exhibiting substantial lossof periodontal support can successfullysupport an FPD in humansfor prolonged periods.5-10These retrospective reports compared abutment teeth supporting prosthesesof various designs
Presented at the American Association for Dental Research meeting, San Francisco, Calif. This study was partially funded by the Medical College of Georgia Biomedical Research Grant No. SO7-RR05795. *Assistant Professor, Prosthodontics, University of Connecticut, School of Dental Medicine. **Associate Professor, Prosthodontics, University of Kentucky, College of Dentistry. ***Associate Professor, Periodontics, Medical College of Georgia, School of Dentistry. ****Professor, Periodontics, Medical College of Georgia, School of Dentistry.
10/l/24060
THEJOURNALOF
PROSTHETIC
DENTISTRY
with similar nonabutment teeth in a different group of patients. Thesefindings, together with other clinical investigations, have shown that plaque control accomplished through personal oral hygiene, periodontal therapy, and consistent professionalmaintenance generally prevented further deterioration of the periodontium.l’-l4 Despite these studies, dentists continue to avoid using periodontally compromisedteeth asabutment teeth for an FPD. Many authors have indicated that abutment teeth for an FPD should possessstability and be “favorably” distributed in the dental arch with “acceptable” crown/ root ratios satisfying Ante’s law.15-lgThese authors have inferred that periodontally compromisedabutment teeth are unsuitable becausethey can be “overstressed” from the additional forces applied to the teeth supporting an FPD. A prospective clinical trial wasconducted to corroborate the retrospective evidence gathered by the Swedish researchers.Specifically, this study compared the probing attachment levels of hypermobile, periodontally compromised abutment teeth supporting a unilateral FPD with levelsin similarly involved nonabutment teeth in the same subject.
MATERIAL
AND
METHODS
The experimental designof the study is illustrated in Fig. To participate in this study, a subject was required to meet specificinitial eligibility criteria. A standardized protocol of dental treatments wasthen administered that enabledthesesubjectsto meet predetermined final eligibility criteria. After a baselineexamination of the periodontium adjacent to the study teeth, the subjectswere reexamined yearly for 2 years. 1.
607
FREILICH
Final Eligibility Criteria Met
Initial Eligibility Criteria Met
Operative Dentistry, Periodontal Therapy, Caries Control
ET AL
Fixed Prosthodontic Treatment, Periodontal Maintenance (2 week intervals for 3 months)
I I
Continued Maintenance irbvals)
Periodontal (3 month
I
Year 0 Exam
Year 1 Exam
Year 2 Exam
I
Data Collection Fig.
Selection
1. Flow chart of study design.
of patients
Twelve healthy adults whosecondition wasdiagnosedas generalizedsevereperiodontitis were selectedfrom a group of patients scheduledfor dental treatment at the Medical Collegeof Georgia,School of Dentistry. To meet the initial criteria of eligibility for this study, eachsubject neededto possess one potential experimental, or abutment tooth, and one control, or nonabutment tooth. This control tooth was the analogoustooth on the contralateral side of the same arch or the opposingarch. The experimental tooth waslocated adjacent to a nonterminal edentulous spaceor to a hopelesslyinvolved tooth requiring extraction. The control tooth waspart of an intact quadrant and wastherefore not located adjacent to a nonterminal edentulous space.All experimental and control teeth satisfiedthe initial eligibility criteria: (1) a minimum of 50% lossof periodontal attachment, asconfirmed by clinical and radiographic examination; (2) presenceof initial probing depths of 5 mm at a minimum of one site adjacent to the study tooth; (3) a tooth mobility of type 2 or 320;and (4) a minimum of 3 mm of osseoussupport, as determined by long-coneperiapical radiographs. The investigation wasexplained to the prospective subjects and informed consentwasobtained. Each subject involved with the study wasawardedan incentive for participation. Nine of the 12 subjectswho entered this study received the necessarydental treatment and were available for the recall and data collection visits. These nine adult subjects,ranging in agefrom 35 to 69years, wereevaluated for a period of 2 years. Two of the three nonparticipants withdrew prior to the completion of periodontal therapy, while one nonparticipant relocated.
Treatment
rendered
After screening was performed and informed consent wasobtained, the subjectsunderwent a similar protocol of
608
dental treatment. This treatment included plaque control instruction with reinforcement, the extraction of hopeless teeth, cariescontrol, periodontal therapy, and fixed prosthodontics. Periodontal therapy consistedof scalingand root planing, followed by surgical pocket reduction at study sites where probing depths remained greater than 4 mm upon reevaluation. Where study teeth were sufficiently mobile to interfere with function, occlusaladjustment, in addition to the removal of local fators, renderedtheseteeth stable for comfortable function. Upon each patient’s completion of active periodontal therapy, a maintenance program of professional plaque control was scheduled every 2 weeks for 3 months,21 followed by a recall scaling/prophylaxis every 3 months. The fixed prosthodontic phaseof treatment began 3 to 6 months after completion of the active periodontal therapy phaseupon attainment of predeterminedperiodontal goals adjacent to the study teeth. The predetermined goalsbecame the final periodontal eligibility criteria that were met prior to the baselineexamination. These were: plaque index (PlI) (Silnessand Liie22)and gingival index (GI) (LBe and Silness23)scoresless than or equal to 0.5; probing depths of lessthan or equal to 4 mm; no bleeding upon probing; and no furcation involvements exceedinggrade I. In addition, eachsubject’soverall PI1 and GI scoresrepresentedby the six Ramfjord teeth24satisfied scoresof 0.5 or less.Fixed prosthodontic treatment consistedof the placement of a three- or four-unit FPD supported by two abutment teeth, onepreviously designatedasthe experimental tooth. The FPDs were constructed with high noble nonceramic alloys and were veneeredwith Isosit (Williams Dental Company, Inc., Buffalo, N.Y.), a steam-curedcomposite resin. The FPDs were assembledintraorally, then presolderedbefore the addition of the veneer. All FPD retainers were madewith supragingival marginsto simplify maintenanceand to serve as a fixed reference for measur-
MAY
1991
VOLUME
96
NUMBER
6
FPDs
AND
PERIODONTALLY
COMPROMISED
TEETH
I. Mean probing attachment levels (7 SD.) at 54 abutment and 54 nonabutment sites for nine subjects at baseline and at 2-year examinations
Table
Abutment Nonabutment
Baseline exam
Two-year exam
4 2 1.3* 521
3.8 5x 1.3 5.2 k 0.9
II. Mean probing depth ( t S.D.) at 54 abutment and 54 nonabutment sites for nine subjects at baseline and at 2-year examinations
Table
Baseline
Change over a-year period + 0.24 - 0.22
Abutment Nonabutment
exam
1.6 -t 0.2* 1.6 t 0.3
Two-year
exam
1.6 + 0.4 1.7 k 0.6
*All values in millimeters.
*All values in millimeters. Table
ing probing attachment levels during the data collection examinations. After placement of the FPD, the subject satisfied the final eligibility criteria and qualified for the baseline examination.
Collection
of data
The periodontium was assessed at six sites adjacent to the experimental and control teeth in each subject at baseline and at the l- and 2-year postinsertion examinations. These assessments were made by measuring attachment levels and probing depths to the nearest millimeter and noting bleeding upon probing to the sulcular base. This examination was accomplished using a 0.70 mm diameter probe tip with Williams markings and a standardized force of 20 gm (Vine Valley Research, Middlesex, N.Y.). Probing attachment levels were measured by using the cementoenamel junction or the retainer margin as a fixed apicocoronal reference to the base of the clinical sulcus. In addition, the PlI and GI scores were recorded at the test sites and at four sites surrounding the six Ramfjord teeth. All measurements were completed by the same examiner and calibrations were made before data collection to attain an acceptable intraexaminer variation.25 The calibration exercises were performed on patients exhibiting similar periodontal disease and restorations who were not included in this study.
Data
analysis
The data were recorded on a computer-ready data collection form, keypunched, and verified. Statistical comparisons were made between the abutment and nonabutment teeth, and between the baseline and a-year measurements. Paired t tests were performed on the attachment level and probing depth measurements and Wilcoxon matched pairs signed-ranks tests were computed for the nonparametric data (PlI, GI, and bleeding upon probing).
RESULTS The mean interval between recall prophylaxis visits from the baseline to the 2-year examination was 4.5 f 2.7 months. Analysis of the 2-year data (n = 9 subjects) was not statistically significant. Clinical differences were also not evident between abutment and nonabutment teeth for probing attachment level, probing depth, bleeding upon
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
III.
Mean plaque and gingival indices (PI1 and
W Baseline
Abutment
exam
Two-year
exam
teeth
PI1 GI Nonabutment PI1 GI
0.15 + 0.19* 0.10 + 0.15
0.37 + 0.31 0.13 f 0.27
0.19 If: 0.14 0.08 * 0.13
0.46 + 0.38 0.28 k 0.35
teeth
*All values in millimeters
probing, and PI1 and GI scores. Statistical differences were not detected between the abutment and nonabutment teeth when the proximal surfaces or facial/lingual surfaces were compared separately. Also, no statistical differences were found between the baseline and a-year measurements for all dependent variables at both abutment and nonabutment teeth. The mean probing attachment level measurements are listed in Table I. After 2 years, there was a mean gain of 0.24 mm for abutment sites and a mean loss of 0.22 mm for nonabutment sites. The mean probing depths for the abutment and nonabutment sites after 2 years were 1.6 + 0.4 and 1.7 & 0.6 mm, respectively (Table II). Six percent of abutment sites bled upon probing after 2 years, compared with 7% of nonabutment sites. There was no bleeding upon probing scored at either the abutment or nonabutment sites at the baseline examination. Mean PlI and GI scores are presented in Table III. The relatively low 2-year PlI and GI scores indicated continued patient compliance with respect to personal oral hygiene. Although no statistical differences were noted for these two variables, there was a trend for higher plaque and gingivitis scores over time.
DISCUSSION The data in this study revealed no statistical or clinically important differences between experimental and control teeth with respect to probing attachment levels or other periodontal parameters. Further, there were no detectable changes in probing attachment levels and probing depths measured at 2 years compared with baseline measures for abutment and nonabutment teeth. The mobile, periodontally compromised experimental and control teeth exhib-
609
FREILICH
ited “stable” probing attachment levels and continued function without discomfort after 2 years. There was no indication that unilateral FPDs without cross arch bracing were detrimental to the supporting periodontium. The small sample size in this study limited the power to detect statistically significant differences. However, the degree of similarity between the abutment and nonabutment sites supported the contention that there were no clinical differences. Before universal application of these findings to the general population, it would be appropriate to retest this study hypothesis with a larger number of subjects. The Swedish reports91 lo, 13*I4 demonstrated that unilateral FPDs were as successful as the cross arch bilateral FPDs for periodontal stability. However, the results they reported continue to be associated with the cross arch stabilization available from extensive multiunit bilateral FPDs with a bilaterally balanced occlusion. The abutment teeth in this study supported only three- to four-unit unilateral FPDs without cross arch bracing. The retention of these periodontally compromised teeth is noteworthy, but their prognosis remains guarded because of the levels of periodontal support. Furthermore, the optimism regarding successful results should be tempered by the limitations of a a-year study and the number of subjects. Earlier studies, 11-14however have previously indicated that the successful long-term maintenance of probing attachment levels at sites susceptible to periodontitis is largely a function of meticulous maintenance by the patient and dentist.
CLINICAL
IMPLICATIONS
OF RESULTS
It is recommended that periodontally compromised, mobile abutment teeth be considered to support FPDs under the following conditions: (1) when there is a lack of other favorably distributed abutment teeth with greater levels of periodontal support; (2) for a carefully selected patient with advanced loss of periodontal support who requires tooth replacement and who has a strong desire to retain the existing dentition; (3) when the patient and dentist are committed to a fastidious plaque control program; (4) when there is a recognition of the guarded prognosis associated with an FPD supported by periodontally compromised teeth because of the higher incidence of tooth fracture2‘j and pulpal problems27; and (5) when there is an awareness of the technical difficulties and prosthodontic failure associated with the management of poorly supported, mobile abutment teeth. With all the factors considered, the use of periodontally compromised abutment teeth to support a unilateral FPD for a highly motivated patient may be the best treatment alternative to an extensive fixed or removable prosthesis. This study concluded that with careful patient selection and good patient oral hygiene, hypermobile, periodontally compromised abutment teeth can support a unilateral FPD comfortably for 2 years. 610
ET AL
SUMMARY This study tested the effect of FPDs on hypermobile abutment teeth with substantially reduced periodontal support. One abutment and one control (nonabutment) tooth of the same type and periodontal condition were selected for study in adult subjects. The treatment consisted of periodontal therapy, placement of a three- and four-unit FPD, and active participation in a 3-month maintenance schedule. The 2-year data (n = 9 subjects) revealed no statistically significant differences (at p < 0.01) between test and control sites for mean probing attachment levels, probing depths, bleeding upon probing, and PI1 and GI scores. No differences were revealed between the mean baseline and 24-month measures for these dependent variables at test and control sites. At 2 years the mean probing depths for test and control sites were 1.64 + 0.44 and 1.74 + 0.60 mm, respectively.
REFERENCES 1. Bhaskar SN, Orban B. Experimental occlusal trauma. J Periodontol 1955;26:2’70-84. 2. Svanberg G. Influence of trauma from occlusion on the periodontium of dogs with normal or inflamed gingivae. Odontol Rev 1974;25:165-78. 3. Poison AM, Meitner SW, Zander HA. Trauma and progression of marginal periodontitis in squirrel monkeys. III. Adpatation of interproximal alveolar bone to repetitive injury. J Periodont Res 1976;11:279-89. 4. Ericsson I, Lindhe 3. Lack of effect of trauma from occlusion on the recurrence of experimental periodontitis. J Clin Periodontol1977;4:115n”
IL,.
5. Nyman S, Lindhe J, Lundgren D. The role of occlusion for the stability of fixed bridges in patients with reduced periodontal tissue support. J Clin Periodontol 1975;2:53-6. 6. Lundgren D, Nyman S, Heijl L, Carlsson FE. Functional analysis of fixed bridges on abutment teeth with reduced periodontal support. J Oral Rehabil 1975;2:105-16. 7. Nyman S, Lindhe J. Persistent tooth hypermobility following completion of periodontal treatment. J Clin Periodontol 1976881-93. 8. Nyman S, Lindhe J. Considerations on the design of occlusion in prosthetic rehabilitation of patients with advanced periodontal disease. J Clin Periodontol 1977;4:1-15. 9. Nyman S, Lindhe J. A longitudinal study of combined periodontal and prosthetic treatment of patients with advanced periodontal disease. J Periodontol 1979;50:163-9. 10. Nyman S, Ericsson I. The capacity of reduced periodontal tissues to support fixed bridge work. J Clin Periodontol 1982;9:469-14. 11. Suomi JD, Greene JC, Vermillion JR, Doyle J, Chang JJ, Leatherwood C. The effect of controlled oral hygiene procedures on the progression of periodontal disease in adults: results after third and final year. J Periodontol 1971;42152-60. 12. Ramfjord SP, Knowles JW, Nissle RR, Shick RA, Burgett FG. Longitudinal study of periodontal therapy. J Periodontol 1973;44:66-77. 13. Lindhe J, Nyman S. The effect of plaque control and surgical pocket elimination on the establishment and maintenance of periodontal health. A longitudinal study of periodontal therapy in cases of advanced periodontal disease. J Clin Periodontol 1975;2:67-79. 14. Axelsson P, Lindhe J. The significance of maintenance care in the treatment of periodontal disease. J Clin Periodontol 1981;8:281-94. 15. Ante IH. The fundamental principles of abutments. Mich State Dent Sot Bull 1926;8:14. 16. Reynolds MJ. Abutment selection for fixed prosthodontics. J PROSTHET DENT 1968;19:483-8. 1’7. Johnston JF, Phillips RW, Dykema RW. Modern practice in crown and bridge prosthodontice. 3rd ed. Philadelphia: WB Saunders Co, 1971. 18. Tylman SD, Malone WFP. Theory and practice of fixed prosthodontics. 7th ed. St Louis: CV Mosby Co, 1978.
MAY
19!31
VOLUME
65
NUMBER
5
FPDsANDPERIODONTALLYCOMPROMISEDTEETH
26. Lindhe J. Textbook of clinical periodontology. Copenhagen, Denmark: Munksgaard Publishing Co, 1984. 27. Langeland K, Rodriques H, Dowden W. Periodontal disease bacteria and pulpal histopathology. Oral Surg 1974;37:257-70.
19. Dykems RW, Goodacre CJ, Phillips RW. Johnston’s modern practice in fixed prosthodontics. 4th ed. Philadelphia: WB Saunders Co, 1986. 20. Miller SC. Textbook in periodontia. Philadelphia: Blakiston Division/ McGraw-Hill Book Co, 1950. 21. Lindhe J, Nyman S, Westfelt E. Critical probing depths in periodontal therapy. J Clin Periodontol 1982;9:323-36. 22. Silneas J, L6e H. Periodontal disease in pregnancy. II. Correlation between oral hygiene and periodontal condition. Acta Odontol Stand 1964;22:121-35. 23. L6e H, Silness J. Periodontal disease in pregnancy. I. Prevalence and severity. Acta Odontol Stand 1963;21:532-51. 24. Ramfjord SP. Indices for prevalence and incidence of periodontal disease. J Periodontol 1959;30:51-9. 25. Smith LW, Suomi JD, Greene JC, et al. A study of intra-examiner variation in scoring oral hygiene status, gingivai infiammation and epithelial attachment level. J Periodontol 1970;41:671-4.
Effect of metal characteristics Donald M. Belles, E. S. Duke, D.D.S., University
of Texas
Reprint requeststo: DR. MARTIN
A. FREILICH SCHOOL OF DENTAL. MEDICINE UNIVERSITY OF CONNECTICUT FARMINGTON, CT 06032
HEALTH
CENTER
Contributing author Ralph V. Katz, D.M.D., Ph.D., Associate Professor, Behavioral Sciences and Community Health, University of Connecticut, School of Dental Medicine, Farmington, Conn.
design and technique on the marginal of the collarless metal ceramic restoration D.D.S., M.S.,* M.S.D.***
Health
Science
Center,
Robert Dental
J. Cronin, School,
Jr., D.D.S.,**
San Antonio,
and
Tex.
This investigation examined the marginal characteristics of the collarless metal ceramic restoration made with two commonly used direct-lift techniques: (1) a porcelain/wax paste and (2) a porcelain/liquid slurry. The metal copings touched the shoulder in half of the groups and were left 0.6 mm short in the other half to comprise the four experimental groups. Marginal seal was evaluated at facial and lingual surfaces on embedded and sectioned specimens for each group. Photo negatives were made of each specimen and projected at a constant magnillcation so that tracings could be made of the space between the die shoulder and corresponding porcelain. Composite surface measurements were made for each sample with a Zeiss Interactive Digital Analysis System instrument to evaluate porcelain adaptation to the shoulder. The porcelainfliquid groups demonstrated significantly smaller (p 5 0.05) facial marginal openings than the porcelain/wax groups. The group made with the porcelain/liquid technique with the metal on the die shoulder produced the most consistent overall results. The porcelain/liquid group with the metal off the shoulder had a statistically larger (p 5 0.05) mean marginal opening from the external margin to a point 0.75 mm to the interior than both techniques with the metal on the shoulder. Lingual marginal adaptation did not vary with each of the four experimental groups. (J PROSTHET DENT 1991;65:61 l-9.)
The opinions contained in this article are those of the authors end are not to be construed as official or as reflecting the views of the United States Air Force or the Department of Defense. Based on a thesis submitted to the graduate faculty, University of Texas, Graduate School of Biomedical Sciences, San Antonio, Tex., in partial fulfillment of the requirements for the Master of
Science degree. Third place, American College of Prosthodontists, John J. Sharry Research Award Competition, Charleston, SC. *Lieutenant Colonel, U.S. Air Force, DC; Assistant Director, Area Dental Laboratory, USAF Clinic Kadene/SGDL, APO San
Francisco. **Colonel, U.S. Air Force, DC; Chairman, Department of Prosthodontics, Wilford Hell Medical Center, San Antonio, Tex. ***Associate Professor, Department of Restorative Dentistry.
10/l/27304
THEJOURNALOFPROSTHETICDENTISTRY
T
he esthetic demand in the region of the labial margin combined with the strength of conventional metal ceramic restorations may explain the increasing popularity of the collarless metal ceramic restoration.’ To simplify these restorations, several techniques have evolved over the years.2-5 A technique introduced by Prince et a1.6 used wax as a binder for the porcelain powder. The use of a wax suspension allows a more consistent separation of condensed porcelain from the die material. It also enhances flowing wax and porcelain into the small marginal gap that results from shrinkage in the original firing. Shrader et al.’ found 11.4% less shrinkage with the porcelain/wax method than with the conventional porcelain/
611
