3. Dent. 1991;
19: 221-225
221
Performance of 400 adhesive bridges fitted in a restorative dentistry department* D. L. Hussey, C. Pagni and G. J. Linden Department
of Restorative
Dentistry,
School of Clinical Dentistry,
Queen’s
University,
Belfast, UK
ABSTRACT The purpose was to present a descriptive report of the clinical performance of adhesive bridges fitted in a university department of restorative dentistry. The case records of 400 consecutive adhesive bridges fitted between November 1984 and June 1989 in the School of Clinical Dentistry, Queen’s University, Belfast were reviewed. The majority of the bridges (66 per cent) were of a fixed-fixed Maryland design: the remainder were Maryland cantilevers (18 per cent), hybrids, i.e. Maryland cantilevers which slotted into conventional units (8 per cent), and Rochette bridges (6 per cent). The mean duration of clinical service at review was 2.7 years. One hundred (25 per cent) of the bridges debonded on at least one occasion. Of the bridges which debonded the average number of debonds was 1.7, with the first debond happening on average 10.7 months after placement (range 1-42 months). Fifty-seven (14 per cent) debonded on one occasion only; 25 (6 per cent) debonded twice and 18 (5 per cent) debonded on three or four occasions. The length of clinical service was a significant factor in relation to debonding. A lower proportion of posterior than anterior bridges debonded and cantilevered and hybrid designs performed well. It is concluded that this investigation confirms the efficacy of resin-bonded bridgework used to replace both anterior and posterior teeth. KEY WORDS: J. Dent. 1991; 1991)
Bridgework,
Resin bonded, Survey
19: 221-225
(Received 24 November
1990;
reviewed
7 January
1991;
accepted 2 1 March
Correspondence should be addressed to: Mr D. L. Hussey, Department of Restorative Dentistry, School of Clinical Dentistry,
Queen’s University,
Grosvenor
Road, Belfast BT12 6BP. UK.
INTRODUCTION The adhesive resin-bonded
bridge has become an accepted alternative to conventional bridgework and partial dentures (Williams et al., 1989). Development of the technique from the use of perforated cast metal as a periodontal splint (Rochette, 1973) to the use of nonperforated cast frameworks retained with specially designed luting resins has been one of the major advances in modern restorative dentistry (Saunders, 1989). Recently there have been several reports of the clinical performance of adhesive bridgework. Kellett (1987) detailed the fate of 108 such restorations in 91 patients from an analysis of clinical records. Clyde and Boyd (1988) reviewed the clinical performance of 122 bridges and splints in 100 patients. Priest and Donatelli (1988) described 58 adhesive bridges which had been in function for up to 4 years and Creugers et al. (1989) reported a controlled clinical trial involving 203 bridges in 183 *Presented at the British Society for the Study of Prosthetic Dentistry. Manchester 1990. @ 1991 Butterworth-Heinemann 0300-5712/91/040221-05
Ltd.
patients. Williams et al. (1989) reported the performance of 99 bridges, the majority of which were perforated, over a IO-year period with the mean period of observation being 3.4 years. Recently Olin er al. (1990) analysed the success of 95 bridges over a mean period of 3.3 years. Taken together the results of these studies demonstrate the efficacy of adhesive bridgework in clinical practice. The continued monitoring of adhesive bridges is important to allow the profession to predict with some degree of certainty the performance of such prostheses in clinical service. The conditions under which the bridgework is constructed may be an important factor (e.g. the performance of bridges supplied in departments of restorative dentistry may not reflect those supplied in general dental practice). Nevertheless, reports from many centres involved in independent, long-term. clinical assessments are an integral part of the process needed to discover factors which may affect clinical efficacy and as such are important. This report details the experience with adhesive bridgework, provided by both undergraduates
222
J. Dent. 1991; 19: No. 4
and staff, in a university dentistry.
department
length of clinical service and grade of clinician responsible for the provision of each bridge were investigated.
of restorative
METHOD
RESULTS
All patients who have had adhesive bridgework provided in the Department of Restorative Dentistry, School of Clinical Dentistry, Queen’s University, Belfast, since November 1984 have been entered in a prospective longitudinal study. These patients had all necessary conservative and periodontal treatment completed before the provision of their bridgework. The decision as to which type of adhesive bridge was most suitable was made solely on clinical grounds by the consultant in charge of each patient. The design of each bridge and the materials used to construct and bond the bridge were agreed between the operator and the consultant. During the course of the study changes in policy on the most appropriate materials to be used for the construction and bonding of the bridges were made as a result of meetings of the senior staff in the department. The clinical procedures were carried out according to a set of guidelines produced by the Department of Restorative Dentistry. Details of the treatment provided were recorded on a form supplied with the bridge when it was collected from the laboratory for insertion. The completed form was placed in the patient’s record folder after the bridge had been successfully placed. Details of any subsequent clinical problems were added to the form ifthe patient had to reattend for treatment specifically related to the adhesive bridgework. The prospective longitudinal study has been planned to involve 500 adhesive bridges and each patient will be recalled for a clinical examination after their bridgework has been in service for 5 years. The first 400 bridges were inserted by June 1989 and the clinical records of these cases were reviewed in September 1989. Laboratory and clinical data including the age at insertion, gender of patient, teeth replaced, abutments involved, luting resin used, preparation of metal, incidence of debonding, the
General data
UPPER RIGHT
The clinical records of 400 adhesive bridges, which had been fitted in 347 patients, were surveyed. For the purpose of this study a Maryland bridge was considered to be an adhesive bridge which had non-perforated cast wings which might or might not have been electrolytically etched. A cantilever bridge was retained by one adhesive wing. A hybrid bridge had a conventional crown which incorporated a dovetail slot as one abutment. The pontic was seated into the dovetail slot during cementation of the adhesive wing of the hybrid. The majority (263; 66 per cent) of the bridges studied were of a fixed-fixed Maryland design. The remainder of the sample comprised 70 cantilevered Maryland bridges, 45 hybrid bridges and 22 Rochette bridges. More of the bridges (248; 62 per cent) were fitted in females and the distribution of each bridge type followed the same pattern in males and females. The patients treated ranged in age from 13.4to 85.1 years with a mean age at insertion of 33.9 years. Distribution
of pontics
The distribution of pontics in the bridges studied is shown in Fig. 1. There were 488 pontics of which the majority (372; 76 per cent) were in the upper arch. Incisor teeth were the commonest teeth to be replaced in both arches and (226; 46 per cent) of all pontics were upper central or lateral incisors. There was considerable variation, with upper incisors accounting for only 28 per cent of hybrid pontics compared with 43 per cent of Maryland and 67 per cent of cantilever pontics. A higher proportion of the bridges (277; 63 per cent) were classified as anterior, i.e. replaced incisor or canine teeth. There were no cases in which second or third molar teeth were replaced. There
60 -
UPPER LEFT 60 -
LOWER RIGHT
Fig. 1. The distribution of pontics in the 400 adhesive bridges studied.
LOWER LEFT
Hussey et al.: Pelformance
of adhesive
bridges
223
Table 1. The number of debonds by bridge type
Total no. Maryland Cantilever Hybrid Rochette
263 70 45 22
All bridges
400
Bridges which debonded no. % 65 12 7 16 100
were 332 bridges with one pontic, 54with two pontics, eight bridges with three and six bridges with four pontics.
Debonds 2
1 no.
%
no.
3 %
25 17 15 73
38 15 710 5 11 7 32
145 46 A227
25
57
25
14
6
It can be seen from Table I that 100 (25 per cent) of the bridges debonded on at least one occasion. A much higher proportion of the Rochette bridges became detached than any of the other bridge types (Table I). Of ‘the bridges which debonded the average number of debonds was 1.7 (s.d. = 0.9) and the range was from 1 to 4 debonds. Fiftyseven (14 per cent) of the bridges debonded on one occasion only and remained in place following reinsertion. Twenty-five (6 per cent) were inserted twice, 11(3 per cent) on three occasions and seven (2 per cent) debonded subsequent to a third insertion. The first debond happened on average 10.7 (s.d. = 10) months after placement, with a range of from 1 to 42 months. The time to first debond was almost the same for each of the bridge types. The frequency distribution of the interval to first debond is skewed to the left (Fig. 2) and 3 1 per cent occurred within 3 months. A further analysis showed that 17 per cent of first debonds happened within 1 month of insertion. Forty per cent of second debonds occurred within 3 months of reinsertion and 41 per cent of third debonds within 3
4 %
83 11 12 15 113
no.
%
: 02 29
20
72
Tab/e II. Debonds by operator with mean length of clinical service of adhesive bridges fitted by each group of operators Bridges
Debonding
no.
Operator
(no.)
Consultants Junior staff Students
2:: 167
Bridges which debonded no. % 3 :y
395 16
Length (years) of clinical service (mean f s.d.) 1.6 zk 1.2 3.1 f 1.6 2.4 f 1.4
months of the second bond failure. The mean interval to first debond in bridges which became detached on only one occasion was 12.8 (s.d. = 10.6) months, which was significantly greater than for bridges which became detached on two or more occasions at 8 (s.d. = 8.5) months (t = 2.4, P < 0.02). Factors affecting
debonding
There was no relationship between debonding and gender; 38 (23 per cent) bridges in males and 65 (26 per cent) in females became debonded. Neither was there a relationship with age at insertion; 44 (24 per cent) of those fitted in patients aged less than 30 years debonded compared with 56 (28 per cent) in the older patients. Length of clinical
service
The mean duration of clinical service at the time of review was 2.7 (s.d. = 1.6) years. Approximately half (195; 49 per cent) of the bridges surveyed had been in place for 2.5 years or less and these were categorized as short service bridges. The remaining 205 (5 1 per cent) had been inserted for longer than this period and were termed long service bridges. The short service bridges had a substantially lower proportion of debonds (11 per cent) than the long service bridges (38 per cent). Operator
Time
(months)
Fig. 2. The interval until first debond for the 100 bridges which debonded at least once.
Junior staff fitted substantially more of the bridges than the student or consultant groups and there was also a significantly higher proportion of debonds in the bridges supplied by junior staff. The bridges provided by junior staff had in general been in clinical service for longer than those of students or consultants (Table II).
J. Dent. 1991; 19: No. 4
224
Table I//. Adhesive bridges using a combination of Panavia Ex and Talladium
DISCUSSION
length
of clinical service
Short Long
(base = 195) (base = 205)
This is an interim report prepared during the course of a continuing longitudinal prospective study. As such it is a retrospective descriptive study of the performance of adhesive bridgework. The large number of variables (e.g. materials used in construction and luting, different operators, etc.) make analysis of the results difficult. Furthermore, the length of time which the bridges had been in clinical service was a major confounding factor in the analysis and accordingly there were limitations on the conclusions which could be drawn. This can be illustrated from the results for the different groups of operators. The lower proportion of debonds in bridges provided by consultants can be explained by the time factor. However, we do not know whether bridges which have been placed recently will subsequently fail. Factors such as increased experience gained during the early part of the study and changes in materials used may also be important. Differences in the complexity of cases accepted for treatment by the different operator groups may also explain some of the differences in debonding between these groups. A controlled clinical trial would allow more reliable conclusions to be drawn. This would require a protocol which reduced the number of variables (e.g. materials). The present study was planned in 1985 to examine the use and performance of all adhesive bridgework provided by a university department. It was inevitable that moditications which improved the performance of adhesive bridges would be reported during the course of this longterm investigation. Before the study started a decision was taken that advances in materials and techniques would be incorporated. The present cross-sectional study should increase our understanding of the clinical problems associated with adhesive bridgework. There have been limited studies of adhesive bridgework provided in general dental practice. Marine110 ef al. (1988) reported the performance of adhesive bridges placed by 17 different clinicians. However, a large percentage (44 per cent) of these were treated by staff in a university clinic and only seven of the clinicians were in general dental practice. The present study also investigated the performance of bridges constructed by many different operators, using a variety of designs and materials. It was very similar to the investigation of Kellett (1987) who argued that such variations within her large series might give a fair indication of what could be expected from adhesive bridgework in general practice. A high proportion (75 per cent) of the resin-bonded prostheses reviewed did not become debonded. Our study, in agreement with previous studies, found that the bridges which debonded often tended to do so at an early stage after insertion (Creugers et al,, 1987), however, in some cases there was a substantial period prior to first debond (up to 42 months). Bridges which debonded repeatedly usually did so very soon after insertion and subsequent debondings occurred at decreasing time intervals. These
PanavialKalladium No. % 159 64
::
Debonds No. % 14 14
9 22
Luting agent Ex (Kuraray Ltd, Osaka, Japan) was the most popular luting agent and was used for (279; 70 per cent) of the bridges. The remaining bridges were luted with Comspan (L.D. Caulk, Delaware, MI, USA) (42; 10 per cent), ABC cement (Vivadent, Schann, Lichtenstein) (24; 6 per cent), and miscellaneous luting agents (55; 14 per cent). Only 16 per cent of bridges luted with Panavia Ex debonded compared with 45 per cent of those luted with other cements. Talladium (Talladium UK Gerrard’s Cross, Bucks, UK) was used in (299; 75 per cent) of the bridges with PGX (Engelhard, Chessington, Surrey, UK) in 61 (15 per cent), and the remaining 40 (10 per cent) using various other metals. Only 20 per cent of Talladium bridges debonded compared with 30 per cent of PGX and 58 per cent of bridges constructed from other metals. The combination of Talladium and Panavia Ex was used in 223 of the bridges and only 28 (13 per cent) of these became debonded. This was substantially less than the 177 bridges which used other combinations of metal and luting agent, of which 72 (41 per cent) became debonded. It can be seen from Table III that the majority of bridges inserted recently use this combination of Talladium and Panavia Ex and that the proportion of debonds with this combination was related to the length of clinical service. Panavia
Etching Electrolytic etching of the metal did not affect the proportion which debonded. One hundred and fifty-five of the bridges were electrolytically etched of which 25 per cent debonded; 245 were not etched of which 25 per cent debonded. The distribution of the various luting cements and metals between electrolytically etched and sandblasted bridges was similar. The mean length of clinical service was the same (2.7 years) for both etched and sandblasted bridges.
Bridge location The majority (277; 63 per cent) of bridges were categorized as anterior, i.e. they replaced incisor or canine teeth, and the remaining 123 (37 per cent) as posterior. The mean length of clinical service was the same (2.7 years) for both anterior and posterior bridges. Eighty (29 per cent) anterior bridges debonded compared with only (20; 17 per cent) posterior bridges.
Hussey et al.: Performance
Table IV. The success of adhesive bridgework by the length of clinical service. A bridge was classified as a success if it did not debond or remained in situ when recemented after one debond Length of clinical service
Bridges (no.)
Successful No.
bridges %
19: 221-225
221
Performance of 400 adhesive bridges fitted in a restorative dentistry department* D. L. Hussey, C. Pagni and G. J. Linden Department
of Restorative
Dentistry,
School of Clinical Dentistry,
Queen’s
University,
Belfast, UK
ABSTRACT The purpose was to present a descriptive report of the clinical performance of adhesive bridges fitted in a university department of restorative dentistry. The case records of 400 consecutive adhesive bridges fitted between November 1984 and June 1989 in the School of Clinical Dentistry, Queen’s University, Belfast were reviewed. The majority of the bridges (66 per cent) were of a fixed-fixed Maryland design: the remainder were Maryland cantilevers (18 per cent), hybrids, i.e. Maryland cantilevers which slotted into conventional units (8 per cent), and Rochette bridges (6 per cent). The mean duration of clinical service at review was 2.7 years. One hundred (25 per cent) of the bridges debonded on at least one occasion. Of the bridges which debonded the average number of debonds was 1.7, with the first debond happening on average 10.7 months after placement (range 1-42 months). Fifty-seven (14 per cent) debonded on one occasion only; 25 (6 per cent) debonded twice and 18 (5 per cent) debonded on three or four occasions. The length of clinical service was a significant factor in relation to debonding. A lower proportion of posterior than anterior bridges debonded and cantilevered and hybrid designs performed well. It is concluded that this investigation confirms the efficacy of resin-bonded bridgework used to replace both anterior and posterior teeth. KEY WORDS: J. Dent. 1991; 1991)
Bridgework,
Resin bonded, Survey
19: 221-225
(Received 24 November
1990;
reviewed
7 January
1991;
accepted 2 1 March
Correspondence should be addressed to: Mr D. L. Hussey, Department of Restorative Dentistry, School of Clinical Dentistry,
Queen’s University,
Grosvenor
Road, Belfast BT12 6BP. UK.
INTRODUCTION The adhesive resin-bonded
bridge has become an accepted alternative to conventional bridgework and partial dentures (Williams et al., 1989). Development of the technique from the use of perforated cast metal as a periodontal splint (Rochette, 1973) to the use of nonperforated cast frameworks retained with specially designed luting resins has been one of the major advances in modern restorative dentistry (Saunders, 1989). Recently there have been several reports of the clinical performance of adhesive bridgework. Kellett (1987) detailed the fate of 108 such restorations in 91 patients from an analysis of clinical records. Clyde and Boyd (1988) reviewed the clinical performance of 122 bridges and splints in 100 patients. Priest and Donatelli (1988) described 58 adhesive bridges which had been in function for up to 4 years and Creugers et al. (1989) reported a controlled clinical trial involving 203 bridges in 183 *Presented at the British Society for the Study of Prosthetic Dentistry. Manchester 1990. @ 1991 Butterworth-Heinemann 0300-5712/91/040221-05
Ltd.
patients. Williams et al. (1989) reported the performance of 99 bridges, the majority of which were perforated, over a IO-year period with the mean period of observation being 3.4 years. Recently Olin er al. (1990) analysed the success of 95 bridges over a mean period of 3.3 years. Taken together the results of these studies demonstrate the efficacy of adhesive bridgework in clinical practice. The continued monitoring of adhesive bridges is important to allow the profession to predict with some degree of certainty the performance of such prostheses in clinical service. The conditions under which the bridgework is constructed may be an important factor (e.g. the performance of bridges supplied in departments of restorative dentistry may not reflect those supplied in general dental practice). Nevertheless, reports from many centres involved in independent, long-term. clinical assessments are an integral part of the process needed to discover factors which may affect clinical efficacy and as such are important. This report details the experience with adhesive bridgework, provided by both undergraduates
222
J. Dent. 1991; 19: No. 4
and staff, in a university dentistry.
department
length of clinical service and grade of clinician responsible for the provision of each bridge were investigated.
of restorative
METHOD
RESULTS
All patients who have had adhesive bridgework provided in the Department of Restorative Dentistry, School of Clinical Dentistry, Queen’s University, Belfast, since November 1984 have been entered in a prospective longitudinal study. These patients had all necessary conservative and periodontal treatment completed before the provision of their bridgework. The decision as to which type of adhesive bridge was most suitable was made solely on clinical grounds by the consultant in charge of each patient. The design of each bridge and the materials used to construct and bond the bridge were agreed between the operator and the consultant. During the course of the study changes in policy on the most appropriate materials to be used for the construction and bonding of the bridges were made as a result of meetings of the senior staff in the department. The clinical procedures were carried out according to a set of guidelines produced by the Department of Restorative Dentistry. Details of the treatment provided were recorded on a form supplied with the bridge when it was collected from the laboratory for insertion. The completed form was placed in the patient’s record folder after the bridge had been successfully placed. Details of any subsequent clinical problems were added to the form ifthe patient had to reattend for treatment specifically related to the adhesive bridgework. The prospective longitudinal study has been planned to involve 500 adhesive bridges and each patient will be recalled for a clinical examination after their bridgework has been in service for 5 years. The first 400 bridges were inserted by June 1989 and the clinical records of these cases were reviewed in September 1989. Laboratory and clinical data including the age at insertion, gender of patient, teeth replaced, abutments involved, luting resin used, preparation of metal, incidence of debonding, the
General data
UPPER RIGHT
The clinical records of 400 adhesive bridges, which had been fitted in 347 patients, were surveyed. For the purpose of this study a Maryland bridge was considered to be an adhesive bridge which had non-perforated cast wings which might or might not have been electrolytically etched. A cantilever bridge was retained by one adhesive wing. A hybrid bridge had a conventional crown which incorporated a dovetail slot as one abutment. The pontic was seated into the dovetail slot during cementation of the adhesive wing of the hybrid. The majority (263; 66 per cent) of the bridges studied were of a fixed-fixed Maryland design. The remainder of the sample comprised 70 cantilevered Maryland bridges, 45 hybrid bridges and 22 Rochette bridges. More of the bridges (248; 62 per cent) were fitted in females and the distribution of each bridge type followed the same pattern in males and females. The patients treated ranged in age from 13.4to 85.1 years with a mean age at insertion of 33.9 years. Distribution
of pontics
The distribution of pontics in the bridges studied is shown in Fig. 1. There were 488 pontics of which the majority (372; 76 per cent) were in the upper arch. Incisor teeth were the commonest teeth to be replaced in both arches and (226; 46 per cent) of all pontics were upper central or lateral incisors. There was considerable variation, with upper incisors accounting for only 28 per cent of hybrid pontics compared with 43 per cent of Maryland and 67 per cent of cantilever pontics. A higher proportion of the bridges (277; 63 per cent) were classified as anterior, i.e. replaced incisor or canine teeth. There were no cases in which second or third molar teeth were replaced. There
60 -
UPPER LEFT 60 -
LOWER RIGHT
Fig. 1. The distribution of pontics in the 400 adhesive bridges studied.
LOWER LEFT
Hussey et al.: Pelformance
of adhesive
bridges
223
Table 1. The number of debonds by bridge type
Total no. Maryland Cantilever Hybrid Rochette
263 70 45 22
All bridges
400
Bridges which debonded no. % 65 12 7 16 100
were 332 bridges with one pontic, 54with two pontics, eight bridges with three and six bridges with four pontics.
Debonds 2
1 no.
%
no.
3 %
25 17 15 73
38 15 710 5 11 7 32
145 46 A227
25
57
25
14
6
It can be seen from Table I that 100 (25 per cent) of the bridges debonded on at least one occasion. A much higher proportion of the Rochette bridges became detached than any of the other bridge types (Table I). Of ‘the bridges which debonded the average number of debonds was 1.7 (s.d. = 0.9) and the range was from 1 to 4 debonds. Fiftyseven (14 per cent) of the bridges debonded on one occasion only and remained in place following reinsertion. Twenty-five (6 per cent) were inserted twice, 11(3 per cent) on three occasions and seven (2 per cent) debonded subsequent to a third insertion. The first debond happened on average 10.7 (s.d. = 10) months after placement, with a range of from 1 to 42 months. The time to first debond was almost the same for each of the bridge types. The frequency distribution of the interval to first debond is skewed to the left (Fig. 2) and 3 1 per cent occurred within 3 months. A further analysis showed that 17 per cent of first debonds happened within 1 month of insertion. Forty per cent of second debonds occurred within 3 months of reinsertion and 41 per cent of third debonds within 3
4 %
83 11 12 15 113
no.
%
: 02 29
20
72
Tab/e II. Debonds by operator with mean length of clinical service of adhesive bridges fitted by each group of operators Bridges
Debonding
no.
Operator
(no.)
Consultants Junior staff Students
2:: 167
Bridges which debonded no. % 3 :y
395 16
Length (years) of clinical service (mean f s.d.) 1.6 zk 1.2 3.1 f 1.6 2.4 f 1.4
months of the second bond failure. The mean interval to first debond in bridges which became detached on only one occasion was 12.8 (s.d. = 10.6) months, which was significantly greater than for bridges which became detached on two or more occasions at 8 (s.d. = 8.5) months (t = 2.4, P < 0.02). Factors affecting
debonding
There was no relationship between debonding and gender; 38 (23 per cent) bridges in males and 65 (26 per cent) in females became debonded. Neither was there a relationship with age at insertion; 44 (24 per cent) of those fitted in patients aged less than 30 years debonded compared with 56 (28 per cent) in the older patients. Length of clinical
service
The mean duration of clinical service at the time of review was 2.7 (s.d. = 1.6) years. Approximately half (195; 49 per cent) of the bridges surveyed had been in place for 2.5 years or less and these were categorized as short service bridges. The remaining 205 (5 1 per cent) had been inserted for longer than this period and were termed long service bridges. The short service bridges had a substantially lower proportion of debonds (11 per cent) than the long service bridges (38 per cent). Operator
Time
(months)
Fig. 2. The interval until first debond for the 100 bridges which debonded at least once.
Junior staff fitted substantially more of the bridges than the student or consultant groups and there was also a significantly higher proportion of debonds in the bridges supplied by junior staff. The bridges provided by junior staff had in general been in clinical service for longer than those of students or consultants (Table II).
J. Dent. 1991; 19: No. 4
224
Table I//. Adhesive bridges using a combination of Panavia Ex and Talladium
DISCUSSION
length
of clinical service
Short Long
(base = 195) (base = 205)
This is an interim report prepared during the course of a continuing longitudinal prospective study. As such it is a retrospective descriptive study of the performance of adhesive bridgework. The large number of variables (e.g. materials used in construction and luting, different operators, etc.) make analysis of the results difficult. Furthermore, the length of time which the bridges had been in clinical service was a major confounding factor in the analysis and accordingly there were limitations on the conclusions which could be drawn. This can be illustrated from the results for the different groups of operators. The lower proportion of debonds in bridges provided by consultants can be explained by the time factor. However, we do not know whether bridges which have been placed recently will subsequently fail. Factors such as increased experience gained during the early part of the study and changes in materials used may also be important. Differences in the complexity of cases accepted for treatment by the different operator groups may also explain some of the differences in debonding between these groups. A controlled clinical trial would allow more reliable conclusions to be drawn. This would require a protocol which reduced the number of variables (e.g. materials). The present study was planned in 1985 to examine the use and performance of all adhesive bridgework provided by a university department. It was inevitable that moditications which improved the performance of adhesive bridges would be reported during the course of this longterm investigation. Before the study started a decision was taken that advances in materials and techniques would be incorporated. The present cross-sectional study should increase our understanding of the clinical problems associated with adhesive bridgework. There have been limited studies of adhesive bridgework provided in general dental practice. Marine110 ef al. (1988) reported the performance of adhesive bridges placed by 17 different clinicians. However, a large percentage (44 per cent) of these were treated by staff in a university clinic and only seven of the clinicians were in general dental practice. The present study also investigated the performance of bridges constructed by many different operators, using a variety of designs and materials. It was very similar to the investigation of Kellett (1987) who argued that such variations within her large series might give a fair indication of what could be expected from adhesive bridgework in general practice. A high proportion (75 per cent) of the resin-bonded prostheses reviewed did not become debonded. Our study, in agreement with previous studies, found that the bridges which debonded often tended to do so at an early stage after insertion (Creugers et al,, 1987), however, in some cases there was a substantial period prior to first debond (up to 42 months). Bridges which debonded repeatedly usually did so very soon after insertion and subsequent debondings occurred at decreasing time intervals. These
PanavialKalladium No. % 159 64
::
Debonds No. % 14 14
9 22
Luting agent Ex (Kuraray Ltd, Osaka, Japan) was the most popular luting agent and was used for (279; 70 per cent) of the bridges. The remaining bridges were luted with Comspan (L.D. Caulk, Delaware, MI, USA) (42; 10 per cent), ABC cement (Vivadent, Schann, Lichtenstein) (24; 6 per cent), and miscellaneous luting agents (55; 14 per cent). Only 16 per cent of bridges luted with Panavia Ex debonded compared with 45 per cent of those luted with other cements. Talladium (Talladium UK Gerrard’s Cross, Bucks, UK) was used in (299; 75 per cent) of the bridges with PGX (Engelhard, Chessington, Surrey, UK) in 61 (15 per cent), and the remaining 40 (10 per cent) using various other metals. Only 20 per cent of Talladium bridges debonded compared with 30 per cent of PGX and 58 per cent of bridges constructed from other metals. The combination of Talladium and Panavia Ex was used in 223 of the bridges and only 28 (13 per cent) of these became debonded. This was substantially less than the 177 bridges which used other combinations of metal and luting agent, of which 72 (41 per cent) became debonded. It can be seen from Table III that the majority of bridges inserted recently use this combination of Talladium and Panavia Ex and that the proportion of debonds with this combination was related to the length of clinical service. Panavia
Etching Electrolytic etching of the metal did not affect the proportion which debonded. One hundred and fifty-five of the bridges were electrolytically etched of which 25 per cent debonded; 245 were not etched of which 25 per cent debonded. The distribution of the various luting cements and metals between electrolytically etched and sandblasted bridges was similar. The mean length of clinical service was the same (2.7 years) for both etched and sandblasted bridges.
Bridge location The majority (277; 63 per cent) of bridges were categorized as anterior, i.e. they replaced incisor or canine teeth, and the remaining 123 (37 per cent) as posterior. The mean length of clinical service was the same (2.7 years) for both anterior and posterior bridges. Eighty (29 per cent) anterior bridges debonded compared with only (20; 17 per cent) posterior bridges.
Hussey et al.: Performance
Table IV. The success of adhesive bridgework by the length of clinical service. A bridge was classified as a success if it did not debond or remained in situ when recemented after one debond Length of clinical service
Bridges (no.)
Successful No.
bridges %
