A 5-year longitudinal study of cantilevered fixed partial dentures compared with removable partial dentures in a geriatric population

A 5-year dentures geriatric

longitudinal compared population

Ejvind Budtz-J@rgensen, Fleming Isidor, D.D.S.,

study of cantilevered with removable partial

fixed partial dentures in a

D.D.S., Dr.Odont.,* and Lic.Odont., Dr.Odont.**

Universit& de GenBve,Switzerland, and Royal Dental College,Aarhus, Denmark Prosthesis function and dental conditions were observed for 5 years in 27 elderly patients treated with mandibular cantilevered fixed partial dentures (FPDs) and in 26 elderly patients treated with distal-extension removal partial dentures (RPDs). All patients were treated with a complete upper denture. The patients were assigned randomly into two treatment groups that had the same composition with regard to sex, age, and distribution of teeth. The patients were under supervised oral hygiene and prosthodontic care. Clinical examination of prostheses, masticatory system, periodontal status, and caries was carried out yearly. Oral hygiene was good, and the periodontal status was maintained in both groups. Caries was observed six times more frequently in the RPD group than in the group with fixed restorations, however. Occlusal and functional conditions deteriorated in the RPD group only. Eight of 42 fixed partial dentures (19%) failed; of these, six were recemented with composite resin. Generally the need for dental and prosthetic follow-up treatment was more pronounced in the RPD group than in the FPD group. (J PROSTHET DENT 1990;64:42-7.)

E

pidemiologic studies have shown that the anterior mandibular teeth usually are retained for the longest period of time and that the canines are the most persistent.‘12 It has been shown that a dentition of the anterior teeth and one to two premolars is present in 20 % to 30 % of elderly patients.t 4 Thus, treatment for them with a complete maxillary denture and a mandibular removable partial denture (RPD) is a common prosthodontic procedure. Recently it was shown, however, that treatment with simple cantilevered fixed partial dentures (FPDs) was an alternative to RPDs for patients in this situation.5 A subjective improvement of chewing function was observed in patients who previously had successfully worn RPDs. Data have indicated that both FPDs and RPDs may influence oral hygiene and mobility of the abutment teeth and hence contribute to caries and progression of periodontal disease.“,7It has also been demonstrated that with proper oral hygiene, minimal periodontal changes occur adjacent to abutment teeth that support fixed or removable partial denture restorations.*-l1 Prosthodontic, functional, and periodontal conditions Supported by a grant from the Danish Dental Association. *Professor and Chairman, Division de Pro&h&e Adjointe et d’0cclusodontie Prosthetique, Univesiti! de Genitve. **AssociateProfessor,Department of Prosthetic Dentistry, Royal Dental College,Aarhus. 10/l/18986

42

during a a-year period of supervised oral hygiene in patients treated with either RPDs or distally extending cantilevered fixed partial dentures were reported in previous studies.12*I3 It was found that the signs and symptoms of mandibular dysfunction were less pronounced in the group of patients treated with fixed restorations. Furthermore, higher plaque scores and more caries were observed in the RPD group compared with the FPD group. This study compared longitudinally functional and prosthodontic conditions and the need for dental and prosthodontic treatment in two groups of patients during a 5-year study period. A subsequent article will focus on the periodontal conditions.14

MATERIAL

AND METHODS

The testing population originally consisted of 53 patients with complete maxillary dentures and mandibular RPDs who were registered for prosthodontic treatment during 1980-1981 in the Department of Prosthetic Dentistry, Royal Dental College, Aarhus, Denmark. On the basis of radiographs, the patients were divided into a FPD group and a RPD group, with the same distribution of the patients according to age and sex as well as remaining mandibular teeth and periodontal conditions (Table I). The RPDs were designed according to accepted principles. They consisted of a cobalt-chromium framework containing either a sublingual or a dental bar (on teeth), occlusal rests, and two clasps for primary retention.15 Care

JULY

1990

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64

NUMBER

1

CANTILEVERED

FPDs

OR RPDs

Table I. Distribution according to sex, age, and number of remaining mandibular teeth of patients treated with cantilevered fixed partial dentures (FPDs) and removable partial dentures (RPDs) Sex No. of patients

Prosthesis FPD RPD

Table

27 26

Women

Men

Mean

Range

Number of teeth +- SD

14 14

13 12

69.7 68.3

61-83 61-81

6.9 i 1.7 7.5 _t 1.7

II. Classification of prostheses and failures of cantilevered fixed partial dentures No. of patients

9-11-unit

prostheses

3-4-unit prostheses 2-3-unit prostheses

No. of prostheses

3-4 2

1 0

12

21

1

1

The patients were examined 1 to 2 months after comple(day zero examination) and reexamined

tion of treatment

OF PROSTHETIC

No. of abutments fractured

8 12

EXAMINATIONS Intervals

JOURNAL

No. of abutments

8 7

was taken to keep bases, connectors, and clasps as far as possible from the gingivae and to sufficiently extend distal-extension denture basesto obtain maximum support from the alveolar ridge and the buccal shelf of the mandible. Treatment with a RPD/complete denture was performed by dental students, but the final result of treatment was evaluated by an experienced prosthodontist. The design of the FPDs has been described in a previous publication.5 The fixed restorations were performed with minimum preparation of the teeth, and their margins were placed as far as possible from the gingivae. Retention of the restorations was secured by parallel pin preparations whenever possible. The 27 patients were provided with a total of 41 cantilevered FPDs with 83 pontics, and 79 teeth were prepared for retainers. Treatment with fixed restorations and a complete maxillary denture was carried out by one of the authors (E. B.-J.). Eight of the patients were provided with lo-unit cantilevered FPDs (Table II). The remaining patients received simple cantilevered FPDs with one or two abutments and one or two cantilevered pontics placed unilaterally or bilaterally. The restorations were designed with open embrasure spaces and spacing from the mucosa of the alveolar ridge. The FPDs were cast in a silver-palladium alloy (Pallorag, Cendres et Meteaux, Biel-Bienne, Switzerland) with pins in iridioplatinum. Facings and pontics were produced of heat-cured acrylic resin (Biodent Plus, De Trey, Wiesbaden, West Germany). The restorations were cemented with zinc-phosphate cement (De Trey).

THE

Age

DENTISTRY

No. of prostheses with cementation failures 1 2 3

Number of patients treate,d with cantilevered fixed partial dentures (FPDs) and removable partial dentures (RPDs) attending yearly examinations and distribution of patients according to clinical dysfunction index (CDI)

Table III.

Year

FPDs

CD1

0

1

2

3

4

5

0

19 5 3

18 6 3

17 7 3

15 10 2

15 8 2

16 6 1

27 20 4 2

21 15 8 3

27 10 10 5

27 9 8 5

25 9 8 5

23 8 8 4

26

26

25

22

22

20

1 2

Attending recall RPDs

0 1 2

Attending recall

1,2,3,4, and 5 years after the day zero examination (Table III). At all examinations, periodontal, dental, functional, and prosthetic parameters were recorded and periodic identical radiographs were obtained.

Periodontal

conditions

and caries

Gingival inflammation was assessed according to the Gingival Index systemi and the state of the oral hygiene according to the Plaque Index system.l” A more comprehensive description of the periodontal conditions, including pocket depth and radiographic bone level, is presented elsewhere.14 Caries was identified clinically and radiographically.

43

BUDTZ-J@RGENSEN

AND

ISIDOR

%

FPDS

RPDS

ACCEPTABLE FPDS

RPDS

60 40 20 0

012345

1 2 3 4 5 YEARS

Fig. 1. Percentage of patients in FPD and RPD groups exhibiting balanced occlusion in retruded contact position (RCP) at various examinations.

Prosthodontic

system

Clinical examination of the masticatory system included palpation of the temporomandibular joints (TMJs) and masticatory muscles, evaluation of function of the TMJs, and movement capability of the mandible. A modification of Helkimo’s Dysfunction Index21 was used to describe the degree of dysfunction.22 Group Die: No dysfunction, evidenced by lack of signs and symptoms of dysfunction Group Dir: Slight dysfunction, evidenced by symptoms such as clicking or crepitation of the TMJ, tenderness to palpation of one muscle, deviation of the mandible on opening (>2 mm), and TMJ sounds Group DI2: Moderate dysfunction evidenced by additional symptoms such as slight or infrequent pain in muscles or TMJ, significant tenderness of several muscles and TMJ on palpation, and slight pain on opening of the mandible (<30 mm) Group DIs: Severe dysfunction as evidenced by additional symptoms such as difficulty in opening the jaws, chewing and swallowing, significant pain by movement of the mandible, and luxation or locking of the mandible Differences between the two groups and differences within the groups at the various examinations were analyzed with the chi square test.

RESULTS The number of patients participating in the yearly examinations are shown in Table I. All patients attended 44

0

1 2 3 4 5 YEARS

Fig. 2. Percentage of patients in FPD and RPD groups exhibiting distinct stability of complete upper denture during occlusion in muscular contact position at various examinations.

conditions

Retention, stability, and occlusal conditions of the complete upper denture and RPD were assessedaccording to the criteria described by Bergman et al.18,ls Presence of denture-induced lesions of the oral mucosa was recorded and classified.20 Soreness to palpation of the anterior part of the alveolar ridge was recorded.

Masticatory

012345

the l- and 2-year examination, but at the 5-year examination, 10 patients were missing. Of these, eight had died and two were unable to come because of debilitating diseases. Initially the mean number of posterior teeth, including pontics of the FPDs, that occluded with the complete upper denture was 4.1 teeth in the group of patients treated with FPDs, corresponding to about two premolars on each side. In the RPD group, the mean number of occluding posterior teeth was 7.3, including the denture teeth of the RPD, corresponding to 2 premolars and one to two molars on each side.

Functional

aspects

By day zero, about 2 months after completion of prosthodontic treatment, slight or moderate signs and symptoms of mandibular dysfunction were present in 30% of the patients with FPDs and 23% of the patients with RPDs (Table III). In two patients who had shown severe signs and symptoms of dysfunction (Da) before treatment with FPDs, the signs and symptoms declined after the restorations were inserted (Dz), but persisted throughout the study period. After 1 year, 33 % of the patients with FPDs and 50% of the patients with RPDs showed signs and symptoms of TMJ dysfunction. Thus, signs and symptoms became significantly aggravated in the RPD group during the study period (p < 0.05). In the group with FPDs, signs and symptoms of dysfunction did not change during the study period (Table III). No significant deterioration of occlusion in the retruded contact position was observed in the two groups of patients (Fig. 1). In the muscular contact position, however, the occlusal stability gradually deteriorated in the RPD group and was significantly reduced at the 5-year examination (p < 0.05). This finding was not so in the group with FPDs (Fig. 2). Acceptable retention of the complete upper denture was observed in most patients in both groups throughout the 5-year study period (Fig. 3). Stability of the complete upJULY

1990

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64

NUMBER

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CANTILEVERED

FPDs

OR RPDs

Table IV. Clinical findings in 5-year follow-up period in patients treated cantilevered fixed partial dentures (FPDs) and removable partial dentures (RPDs) FPDs (2’7 patients)

Findings

57 5 5 17 7 12 10

10 2 2 15 4 8 1 -

Dental caries Endodontic complications Tooth fractures Denture stomatitis Denture ulcer Irritation from sublingual bar Prosthesis failures Denture failures Clasp fractures

RPDs (26 patients)

4

Table V. Number of procedures performed during &year follow-up period for patients treated with cantilevered fixed partial dentures (FPDs) and removable partial dentures (RPDs) FPD (27 patients)

Amalgam or composite filling Endodontic treatment Tooth extraction Treatment with FPDs Treatment with RPDs Major repair of framework New complete upper denture Relining of complete upper denture Relining of RPD Recementation of FPD

RPD (26 patients)

10

61

2

5

1 1

11 -

2 6

2 6 3 8

-

-

7 6

-

per denture to pressure by the index finger in the premolar region declined in the RPD group, however, and was significantly reduced at the examination after 4 and 5 years (p < O.Ol), but not in the group with FPDs (Fig. 4). Stability and retention of RPDs were maintained during the study period. Soreness to palpation of the anterior part of the alveolar ridge of the maxillae was observed most frequently in the RPD group. Soreness was observed in five of the 159 examinations of patients with fixed restorations compared with 17 of 143 examinations of RPD patients.

Oral hygiene

and periodontal

conditions

Generally, the patients showed an acceptable oral hygiene through the study period, with a mean plaque index of 0.4 to 0.7 in the FPD group and 0.7 to 1 in the RPD group. A more thorough evaluation of the periodontal aspects of this study is presented elsewhere.i4 There was no progression of periodontal disease adjacent to the abutment teeth, however, in any of the groups. THE

JOURNAL

OF PROSTHETIC

DENTISTRY

% ACCEPTABLE 100

r

FPOS

RPDS

80 60

0

0123L5

1 2

3 .% 5 YEARS

Fig. 3. Percentage of patients in FPD and RPD groups with distinct retention of complete upper denture at various examinations.

% ACCEPTABLE 100

QPDS

FPDS

80 60

0

0123L5

1 2 3 4 5 YEARS

Fig. 4. Percentage of patients in FPD and RPD groups with distinct stability of complete upper denture to pressure by index finger in premolar region at various examinations.

Other clinical

findings

Clinical findings observed during the &year study period are listed in Table IV. The most striking observation was that 57 dental carious lesions were observed in the RPD group compared with 10 lesions in the group with FPDs. Mainly root caries was observed, but tooth surfaces in contact with the RPD did not exhibit frequent caries. Tooth fractures in the RPD group included three abutment and two nonabutment teeth. Two abutment teeth fractured for FPDs. Of these, one was vital and an abutment in a IO-unit restoration; the other was a nonvital abutment for a twounit cantilevered restoration. Retention failed in six FPDs that were one of 10 units, two of three units, and three of two units (Table II). During the follow-up period, 10 upper RPDs failed because of framework fracture, loss of framework fit, or tooth extractions. During the study period, lesions in the mucosa adjacent to the sublingual bar were observed in 12 of 16 patients wearing RPDs with this type of major connector (Table IV). 45

BUDTZ-J@tGENSEN

Treatment During the 5-year study period, the need for dental and prosthodontic treatment was more pronounced in the RPD group than in the FPD group (Table V). Thus, 61 fillings were placed in the RPD group compared with 10 in the FPD group. Eleven teeth, including five direct abutment and two indirect abutment teeth, were extracted in the RPD group compared with one abutment tooth for an FPD. The reasons for the extractions were endodontic or cariologic complications as well as tooth fractures. Several of these teeth could have been maintained if the patients had been willing to accept more costly treatment with crowns, however. One three-unit fixed cantilevered restoration had to be remade because of fracture of the pins. One two-unit fixed cantilevered restoration that failed was not replaced. The remaining six FPDs that failed were recemented with composite resin using the acid-etched technique and an enamel bonding agent. All failed abutments, except one, were with parallel pin preparations. During the observation period, treatment with new prostheses and relining of existing prostheses in the mandible or the maxillae were performed more frequently in the RPD group than in the FPD group.

DISCUSSION This study seems to be the first investigation designed to compare longitudinally functional, periodontal, and prosthodontic aspects of treatment with CantileveredFPDs or RPDs for distal-extension ridges. The composition of the two treatment groups was comparable with regard to age, sex, and distribution of remaining teeth as well as the initial dental and periodontal status. In both groups of patients, prosthodontic treatment seemedto improve chewing ability and occlusal stability of the complete maxillary denture.5 During the 5-year study period, eight, or about 20%, of the FPDs failed because of loss of retention or fracture of abutments. This relatively high failure rate is comparable to that observed by Randow et aLz3 who found technical failures in 16.1% of patients with one-unit cantilevered pontics and 33.7% of patients with two-unit cantilevered pontics after 6 to 7 years. On the other hand, it was shown that in a population with severe loss of alveolar bone support where fixed reconstructions with cantilevered pontics were used to splint the remaining teeth and balance the occlusion, the failure rate was about 8% after 5 to 10 years.l’* 24Thus, it is likely that the relatively high failurerate in the present study was because pin restorations were mainly used for the retainers. The reason for use of pins was to conserve tooth structure and to allow substitution of the FPDs with RPDs if the FPDs did not provide satisfactory occlusal support for the maxillary complete denture. Undoubtedly, some of the failures might have been prevented by using full crowns as retainers. It is noteworthy, however, that the FPDs did not work loose again when the acid-etch

46

AND

ISIDOR

technique and an enamel bonding agent were used for recementation. In the RPD group, the caries activity appeared to be higher than in the FPD group, since six times as many carious lesions were observed in the RPD group during the 5-year study period. In a study by Bergman et al.,s 112 fillings were placed in 27 patients during a lo-year observation period, which corresponds well with the 61 fillings placed in the present study during a 5-year period. One possible reason for the relatively high incidence of caries in the RPD group compared with the group of patients with FPDs is that some of the tooth surfaces at caries risk were covered by retainers and relatively few teeth in the RPD group were restored by crowns.12 This cannot account for the relatively low incidence of root caries in the group with fixed restorations, however. Another reason could be that plaque accumulation tended to be highest in the RPD group,14 although the patients in both groups were subjected to the same follow-up treatment. Furthermore, insertion of RPDs has been shown to be associated with a quantitative increase of Streptococcus mutans in saliva, thereby contributing to the increased risk of caries in RPD wearers.25 That more teeth were extracted in the RPD group than in the group with FPDs was not entirely a reflection that tooth morbidity was increased in the RPD group. Some of the carious or fractured teeth were extracted because the patients did not want necessary treatment with crowns. During the study period, no severe signs or symptoms of TMJ dysfunction were observed in any of the treatment groups. Compared with the situation by day zero, however, signs and symptoms of mandibular dysfunction became more pronounced in the RPD group, whereas no significant changes were observed in the FPD group. Furthermore, deterioration of stability of the maxillary denture and occlusal stability, as well as increased soreness of the anterior part of the maxillary ridge, were more pronounced in the RPD group than in the FPD group. The reason could be altered occlusal relationships due to resorption of the residual alveolar ridge under the distal-extension denture bases. That changes of the relationship between the denture and the supporting structures did take place in the RPD group was supported by the fact that lesions of the oral mucosa adjacent to the sublingual bar were a frequent finding.

CONCLUSION This study has confirmed previous observations that treatment with distally extending cantilevered FPDs is a favorable alternative to treatment with RPDs in elderly patients. Signs and symptoms of TMJ dysfunction developed in the RPD group during the study period, but not in the FPD group. Furthermore, occlusal stability and denture stability deteriorated more often in the RPD group than in the FPD group. Together, these findings indicate

JULY

1990

VOLUME

64

NUMBER

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CANTILEVERED

FPDs OR RPDs

that a cantilevered prosthesis provides more long-term occlusal stability than a RPD. The risk of caries and its consequences, such as tooth fractures, extractions, and endodontic treatments, was much higher in the RPD group than in the FPD group. The reason could be that the denture wearers develop a more caries-active plaque and that the RPDs contributed more to plaque accumulation than the FPDs. In addition, the number of tooth surfaces at caries risk was possibly higher in the RPD group than in the FPD group, since relatively few teeth had been restored with crowns in the RPD group. It is likely that the retention failures of the cantilevered FPDs could be minimized by (1) cementation of pin restorations, using the acid-etch technique, enamel bonding agents, and composite resin for cementation, and (2) using full crowns instead of pin restorations. This study suggests that the economic advantages of treatment with RPDs become less obvious when the long-term need for various dental treatments is evaluated against those needed after treatment with cantilevered FPDs.

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TEE JOURNAL

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9. Chandler JA, Brudvik JS. Clinical evaluation of patients eight to nine years after placement of removable partial dentures. J PROSTHET DENT 1984;51:736-43. 10. Rissin L, Feldman RS, Kapur KK, Chauncey HH. Six-year report of the periodontal health of fixed and removable partial denture abutment teeth. J PROSTHET DENT 1985;54:461-7. 11. Valderhaug J. Periodontal conditions and cartous lesions following the insertion of fixed prostheses: a lo-year follow-up study. Int Dent J 1980;30:296-304. E, Isidor F. Cantilever bridges or removable partial 12. Budtx-Jdrgensen denture in geriatric patients: a two-year study. J Oral Rehabil 1987; 14:239-49. conditions following treat13. Isidor F, Budtx-J@rgensen E. Periodontal ment with cantilever bridges or removable partial dentures in geriatric patients. A 2-year study. Gerodontics 1987;3:117-21. E. Periodontal conditions following treat14. Isidor F, Budtx-J$rgensen ment with bridges or removable partial dentures. A B-year study. J Periodontol 1990,61:21-6. 15. Derry A, Bertram U. A clinical survey of remcvable partial dentures of 2 years usage. Acta Odontol Stand 1970;28:581-98. 16. Lee H, Silness J. Periodontal disease in pregnancy. I. Prevalence and severity. Acta Odontol Stand 1963;21:532-51. 17. Silness J, LBe H. Periodontal disease in pregnancy. II. Correlation between oral hygiene and periodontal condition. Acta Odontol Stand 1964;22:121-35. a-year study of 18. Bergman B, Carlsson GE, Hedegdrd B. A longitudinal a number of full denture cases. Acta Odontol Stand 1964;22:3-26. 19. Bergman B, Hugoson A, Olsson C-O. Periodontal and prosthetic conditions in patients treated with removable partial dentures and artificial crowns. A longitudinal 2-year study. Acta Odontol Stand 1971; 29621.38. E. Oral mucosal lesions associated with wearing of re20. Budtz-Jdrgensen movable dentures. J Oral Path01 1981;10:65-80. 21. Helkimo M. Studies on function and dysfunction of the masticatory system. Swed Dent J 1974;67:101-21. P, Fejerskov 0. Man22. Budtz-Jdrgensen E, Luan W-M, Holm-Pederaen dibular dysfunction related to dental, occlusal .md prosthetic conditions in a selected elderly population. Gerodontics 1985;1:28-33. 23. Randow K, Glantx PO, Zijger B. Technical failures and some related clinical complications in extensive fixed prosthodontics. An epidemiological study of long-term clinical quality. Acta Odontol Stand 1986; 44241.55. 24. 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. 25. Mihalow DM, Tinanoff N. The influence of removable partial dentures on the level of Streptococcus mutans in saliva. J PROSTHET DENT 1988;59:49-51. Reprint requests to: DR. &VIND BUDTZ-J@RGENSEN DIVISION DE PROSTH~~SE ADJOINTE ET D’OCCLUSODONTIE PROSTHETIQUE 18 RUE BARTHI~~L~~MY-MENN, CH-1211 GEN~~VE SWITZERLAND

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