Journal of Dentistry,
7, No. 1, 1979,
pp. l-9.
Printed in Great Britain
A survey of the teaching of partial denture construction in dental schools in the United Kingdom* M. J. Barsby,
BDS, FDS RCS
W. D. Schwarz, Department
BDS, MDSc
of Prosthetic Dentistry,
The London Hospital Medical College Dental School,
London
ABSTRACT
Previously reported work has suggested that there is a disparity between what is taught to undergraduates regarding the design and construction of metal-based partial dentures and what is done by the practising dentist. A survey of the eighteen dental schools in the United Kingdom (seventeen undergraduate and one postgraduate) was carried out by means of a postal questionnatie. The purpose of this wasto elucidate what is taught concerning the design and construction of partial dentures. A one hundred per cent response was achieved. The results provide evidence that much common ground exists in the teaching of different schools, and comparison with previously reported work supports the hypothesis that there is a divergence between teaching and practice.
INTRODUCTION Teachers of clinical dentistry, dental students and general dental practitioners frequently presume that differences exist between what is taught to undergraduates and what is done in general practice. A survey of commercial dental laboratories specializing in the fabrication of cobalt-chromium castings for partial dentures showed that such differences may not be
restricted to matters of clinical technique (Schwarz and Barsby, 1978). This survey provided evidence that in many instances the responsibility for diagnosis and prescription of partial denture design was abandoned by the dentist and delegated to the laboratory. It was decided to test the hypothesis that there is a disparity between the teaching and practice of partial denture construction by carrying out two further surveys. The purpose of the first of these, the findings of which are presented here, was to elicit what is actually taught in dental schools regarding some aspects of partial denture construction. Later, it is proposed to survey 1000 practitioners to obtain information about what is practised. MATERIALS AND METHODS A questionnaire was sent to the heads of the departments of prosthetic dentistry at the eighteen dental schools in the United Kingdom. This included the one postgraduate school. A covering letter explaining the nature and purpose of the survey and a stamped addressed envelope for the return of the questionnaire were enclosed. The questionnaire included twenty-two questions seeking information about a range of activities involved in partial denture construction. A question was also included on the use *Presented at the Annual Conference of the British Society for the Study of Prosthetic Dentistry in March 1978.
2
Journal of Dentistry, Vol. ~/NO. 1
Table LRecommended texts for students Author
of textbook
Osborne and Lammie (1974) Henderson and Steffel (1973) Fenn, Liddelow and Gimson (1962) Neil1 and Walter (1977) Applegate (1959) Bates (1978) Miller (1973) Harty and Roberts (1974)
No. of schools
8 4 2 2 1 1 1 1
of textbooks. For many questions a graduated response was used. Other questions required a choice of one or two alternative answers. Instructions for the completion of the questionnaire were as follows: a. Please answer as directly as possible. b. If a choice is provided, please give preferred answer. c. The following guidelines are suggested: Never Rarely Occasionally Frequently Generally Always
0 1 - 9 per cent 10 - 49 per cent 50 - 89 per cent 90 - 99 per cent 100 per cent
d. Please complete every question-do not leave blanks. Comments on the questionnaire were invited, for which a separate sheet was included. Individual schools were identified only by numbers. Questionnaires were also distributed to all staff within the Department of Prosthetic Dentistry at The London Hospital Medical College in an attempt to check whether there is a difference between what is actually taught and what the head of a department thinks is taught.
RESULTS Question 1 asked respondents to list recommended textbooks and department-produced texts (Table I). In addition to the books listed, eight other texts not directly concerned with partial denture construction were mentioned. Two schools made no response to either part of this question. One school answered that no textbooks were considered suitable and one replied that they used alI British and some American publications. Department-produced texts as hand-outs were used by nine schools. Questions 2, 3 and 4 related to the teaching of the use of study casts, whether these are articulated and whether the patient requiring partial dentures should be examined for possible disturbance of maxillomandibular relations (Table II). Questions 5 and 6 dealt with surveying, and the responses were as in Table III. Questions 8 and 9 dealt with tooth preparation. Seventeen schools teach tooth preparation as a standard procedure and one school gave a qualified affirmative response. The purposes
3
Barsby and Schwarz: Teaching of partial denture construction
Tab/a II. Use of study casts and maxillomandibular
Response Always Generally Frequently Occasionally Rarely Never
Use of study casts 15 1 2
Tab/e 111.Surveying of study and master casts
Response
Surveying of study casts
Surveying of mastercast
14 2 1 1
18
Always Generally Frequently Occasionally Rarely Never
relations Examination for disturbance of maxillomandibular relations
Articulated study casts 9 5 1 3
13 1 1 2
Tab/e IV. Purposes for which tooth preparation is Carried out No. of schools
Procedure Rest seat preparation Creation of guide planes Recontouring buccal/lingual shape Others
Tab/e VI. Requirement prescription of denture
Tab/e V. Stage at which records are made Stage For study casts Before casting is made After casting is made
occlusal relationship
No. of schools 18 12 13
Response Always Generally Frequently Occasionally Rarely Never
to
17 11 15 4
submit
full written
Before mouth preparation
As instruction to laboratory
13 3
14 3 1
2
for which tooth preparation is carried out are shown in Table IV. Additional purposes mentioned included ‘correction of anomalies’, occlusal correction, creation of undercuts, improving appearance and cleanability and creation of space. Question 10 sought to determine at which stage occlusal relationship records are made (Table V).
Question 11 related to making a written commitment towards denture design before mouth preparation and the subsequent instructions to the laboratory (Table VZ). Questions 12, 13 and 14 related to the place of other treatment in the treatment plan for the partially edentulous patient. Fourteen schools teach that periodontal treatment should be carried out before prosthetic treatment. Two schools allowed periodontal treatment to proceed concurrently and two schools provided periodontal treatment after prosthetic treatment. With regard to abutment tooth restoration, sixteen schools teach that this should
4
Journal of Dentistry, Vol. ~/NO. 1
Table VII. Use of special trays Response
Table VIII. Choice of impression materials No. of schools Material
Always Generally Frequently Occasionally Rarely Never
Primary impression
Master impression
17 1
17 7 7 3 3
Alginate Silicone rubber Mercaptan rubber Polyether rubber Composition
4
Table IX. Free end saddle dentures No. of schools teaching use of particular procedures
Response ~-
a
Always Generally Frequently Occasionally Rarely Never
4 3 1
Table X. Materials used for major connectors
Response Always Generally Frequently Occasionally Rarely Never
Cast metal P/ /P 2 5
a 2
2 11 2 2
Resin P/ 1 1 7 5 3
/P 1 1 3 1 11
Wrought metal P/ /P 1
3 15
1 3 7 6
be carried out with the partial denture design in mind. One school gave no response and one did not consider abutment tooth restoration from this viewpoint. Question 14 asked whether other departments considered abutment tooth restoration with a view to partial denture design. Almost every school gave a qualified affirmative response. Three schools did not think other departments paid sufficient attention to this. Questions 7 and 15 referred to the use of ‘special’trays and choice of impression material respectively. The responses are shown in Tables VZZand VZZZ. One school used composition as the only material for the primary impression. Schools which indicated the use of composition for the master impression also specified other materials, which were presumably used in combination. Two questions were included concerning free end saddle dentures. Question 16 asked whether particular procedures are taught as applicable for this type of denture and the results are shown in Table IX. Two schools did not respond to this question but did answer Question 17, which asked which procedures are employed. Nine schools teach the use of ‘stress-breaker’devices, and 15 schools teach the use of particular impression procedures.
Barsby and Schwarz:
Teaching
of partial denture
5
construction
. . b * . b ??
. .
.
. .
. .
b
??
L
1
2
3
4
5
6
Hours Fig. 1. Total average chairside time for dental school staff when treating a patient by provision of a partial denture.
Questions 18, 19 and 20 related to major connectors. The results are shown in Table X. For both cast metal and resin major connectors, one school gave a qualified response stating ‘wherever indicated’. Question 21 asked from which source students obtain patients. The replies indicated that most patients come directly to departments of prosthetic dentistry, followed in order of frequency by referrals from departments of conservative dentistry, periodontology and oral surgery. Two schools reported the use of a common waiting list for all departments. In Question 22 the respondent was asked to indicate the average total chairside time employed by himself or his staff when treating a patient by provision of a partial denture. The results are shown in Fig. 1. Some respondents indicated a range, one quoted time taken by students and one commented that no simple cases were treated by staff. Nine schools made written comments on the questionnaire, mostly in the form of explanatory notes in relation to particular questions. Some respondents pointed out possible ambiguities in the questionnaire and some suggested further topics on which questions might have been included. The intra-departmental questionnaires showed considerable agreement in the teaching of the staff in the one department of prosthetic dentistry examined in this way. DISCUSSION No one textbook of partial denture construction is used universally in the eighteen schools
surveyed. This contrasts with a survey of American dental schools by Bowman (1970) which showed that thirty out of forty-three schools investigated used McCracken’s Partial
6
Journal of Dentistry, Vol. ~/NO. 1
&nme Construction (Henderson and Steffel, 1973). Schools in the United Kingdom often used more than one text and many produce hand-outs and distribute photocopies of select-
ed Papers. Where members of a department had produced a textbook it was recommended. Thirty out of forty-three American schools required the use of a laboratory manual, whereas only one United Kingdom dental school specifically mentioned this. Study casts were almost universally accepted but slightly fewer schools taught the necessity to mount them on an articulator. These findings are at variance with the response to Question 4, since a higher proportion of schools always examine for disturbances of maxillomandibular relations but presumably this is only carried out clinically. Bowman (1970) reported that all of the American schools in his study used study casts and 75 per cent of them insisted that these be mounted on a semi-adjustable articulator. One school in the present survey, using composition primary impressions, always surveyed the resultant study cast. This is incompatible with the ability of the material to reproduce undercuts. The majority of schools teach the use of special trays. It may be that those who do not, teach the use of secondary impression methods such as the ‘altered cast’ technique of Applegate (1959). Question 17 confirms that special impression procedures for the free end saddle denture are widely taught, although it is not clear whether this is done routinely. The use of composition together with an elastomeric material suggests that some schools have a good selection of stock trays available and that these are modified, obviating the use of special trays. Tooth preparation is almost universally taught, and preparation of rest seats is the most common procedure. This contrasts with previously reported data from a survey of commercial laboratories specializing in cobalt-chromium castings (Schwarz and Barsby, 1977), which showed that only 4.6 per cent of 1853 casts had any evidence of tooth preparation. There was universal agreement for the use of occlusal relationship records at some stage of partial denture construction. The laboratory survey previously quoted showed that 40 per cent of casts sent to commercial laboratories for castings to be made were not accompanied by any indication of the occlusal relationship. All schools found it necessary to prepare either written instructions or a drawing of the denture design for the laboratory. This differs from previous findings in which only 36 per cent of work sent to commercial laboratories was accompanied by written or drawn instructions for the cobalt-chromium appliance (Schwarz and Barsby, 1977). Quinn (1971) commented that dental curricula appeared to be ineffective in teaching the use of dental laboratory personnel. He stated: ‘dentists are produced who not only cannot carry out laboratory work to the standard of a laboratory technician nor can they effectively instruct them’. Brown (1965) reported that in thirty-eight states (of the United States of America) dentists are required by law to provide written instructions for laboratory work and the work must only be carried out by the laboratory on receipt of written instructions from a licensed dentist. A survey of dentists’ opinions by the American Dental Association (1959) reported the responsibilities of a dentist with regard to ‘removable partial denture service’. The following items were considered desirable: accurate impressions for study casts; provisional survey and design; preparation of retentive, reciprocal, rest areas and guide planes; final impressions to be cast on dentists’ premises; final survey and design to the drawn on the cast; path of insertion to be marked; free end saddle areas to be reproduced by functional impressions; functional ‘chew-in’for jaw relationships.
Barsby and Schwarz:
Teaching
of partial denture
construction
7
With regard to the restoration of abutment teeth, there was universal consideration by United Kingdom departments of prosthetic dentistry for this to take account of the denture design, but a very qualified response with regard to the view of other departments. This suggests room for improved integration in teaching in most schools. Every school is aware of the problems of free end saddle dentures and all schools teach that special consideration should be given to this, the most common approach being the use of impression materials. Dental schools suggest the use of cast metal major connectors more commonly for lower partial dentures than for upper dentures. Resin major connectors are more commonly used for upper partial dentures than for lower ones. Wrought metal major connectors are used more frequently in the lower jaw than in the upper. The ratio of resin dentures to metal dentures provided within the General Dental Services is approximately 9 : 1 (Dental Estimates Board Annual Report, 1976). Within dental schools the commonest range of time taken by staff for the clinical stages of partial denture construction falls in the range 2-3s hours. Clinical time is important because it indicates the cost of procedures. The cost of partial denture construction by heads of departments of prosthetic dentistry could be between g20 and ti0 if based on a value for practice clinical time within the National Health Service of &l 1 per hour (British Dental Association, 1978). The laboratory cost for partial dentures varies between 225 and ti0, comprising &15-a0 for the cobalt-chromium framework and approximately &lo for the other stages. The total cost for clinical and laboratory work would therefore range between &45 and 035. This contrasts markedly with the current fees allowed within the National Health Service General Dental Services (1976) where the total fee allowed for metal-based partial dentures ranges between 229 and g32 inclusive of laboratory fees. After deduction of laboratory fees, the NHS fees represent a maximum outlay of time on the part of the practitioner of half an hour. More complex appliances would therefore require an investment of time given gratuitously. It is clear that dental schools in the United Kingdom cannot train students to provide partial dentures at the speed required for the rate of remuneration they are likely to encounter in practice. Future reviews of the NHS fee structure for partial denture treatment must remedy this unsatisfactory situation.
Acknowledgements We would like to thank all heads of departments who participated in the survey and the staff of our own department who also completed questionnaires and offered advice on the preparation of this paper. We are indebted to Miss E. Brand for secretarial assistance and to Mr G. Walter for photographic services. REFERENCES
American Dental Association (1959) Survey of dentist opinion III. Dental drugs; dental laboratories; reciprocity. J. Am. Dent. Assoc. 59, 512-5 17. Applegate 0. C. (1959) Essentials of Removable Partial Denture Prosthesis, 2nd ed. Philadelphia, Saunders, pp. 230-256. Bates J. F. (1978) Removable Partial Denture Construction, 2nd ed. Bristol, Wright. Bowman J. F. (1970) Removable partial prosthodontics: comparison surveys-1964 and 1969. J. Dent Educ. 34,93-97.
Journal of Dentistry, Vol. ~/NO. 1
8
British Dental Association (1978) Personal communication. Brown E. T. (1965) The dentist, the laboratory technician and the prescription law. J. Prosthet. Dent. 15, 1132-l 138. Fenn H. R. B., Liddelow K. P. and Gimson A. P. (1962) Clinical Dental Prosthetics, 2nd ed. London, Staples. Harty F. J. and Roberts D. H. (ed.) (1974) Restorative Procedures for the Practising Dentist, Bristol, Wright. Henderson D. and Steffel V. L. (ed.) (1973) McCracken’s Removable Partial Prosthodontics, 4th ed. St Louis, Mosby. Miller E. L. (1973) Removable Partial Prosthodontics. Baltimore, Williams and Wilkins. National Health Service General Dental Services (1976) Statement of Dental Remuneration, Section V. Neil1 D. J. and Walter J. D. (1977) Partial Denture Prosthetics. Oxford, Blackwell. Osborne J. and Lammie G. A. (1974) Partial Dentures, 4th ed. Oxford, Blackwell. Quinn I. (1971) Teaching pre-clinical removable partial dentures. J. Dent. Educ. 35, 54354.5.
Schwarz W. D. and Barsby M. J. (1978) Design of partial dentures in dental practice. J. Dent. 6,166-170.
7, No. 1, 1979,
pp. l-9.
Printed in Great Britain
A survey of the teaching of partial denture construction in dental schools in the United Kingdom* M. J. Barsby,
BDS, FDS RCS
W. D. Schwarz, Department
BDS, MDSc
of Prosthetic Dentistry,
The London Hospital Medical College Dental School,
London
ABSTRACT
Previously reported work has suggested that there is a disparity between what is taught to undergraduates regarding the design and construction of metal-based partial dentures and what is done by the practising dentist. A survey of the eighteen dental schools in the United Kingdom (seventeen undergraduate and one postgraduate) was carried out by means of a postal questionnatie. The purpose of this wasto elucidate what is taught concerning the design and construction of partial dentures. A one hundred per cent response was achieved. The results provide evidence that much common ground exists in the teaching of different schools, and comparison with previously reported work supports the hypothesis that there is a divergence between teaching and practice.
INTRODUCTION Teachers of clinical dentistry, dental students and general dental practitioners frequently presume that differences exist between what is taught to undergraduates and what is done in general practice. A survey of commercial dental laboratories specializing in the fabrication of cobalt-chromium castings for partial dentures showed that such differences may not be
restricted to matters of clinical technique (Schwarz and Barsby, 1978). This survey provided evidence that in many instances the responsibility for diagnosis and prescription of partial denture design was abandoned by the dentist and delegated to the laboratory. It was decided to test the hypothesis that there is a disparity between the teaching and practice of partial denture construction by carrying out two further surveys. The purpose of the first of these, the findings of which are presented here, was to elicit what is actually taught in dental schools regarding some aspects of partial denture construction. Later, it is proposed to survey 1000 practitioners to obtain information about what is practised. MATERIALS AND METHODS A questionnaire was sent to the heads of the departments of prosthetic dentistry at the eighteen dental schools in the United Kingdom. This included the one postgraduate school. A covering letter explaining the nature and purpose of the survey and a stamped addressed envelope for the return of the questionnaire were enclosed. The questionnaire included twenty-two questions seeking information about a range of activities involved in partial denture construction. A question was also included on the use *Presented at the Annual Conference of the British Society for the Study of Prosthetic Dentistry in March 1978.
2
Journal of Dentistry, Vol. ~/NO. 1
Table LRecommended texts for students Author
of textbook
Osborne and Lammie (1974) Henderson and Steffel (1973) Fenn, Liddelow and Gimson (1962) Neil1 and Walter (1977) Applegate (1959) Bates (1978) Miller (1973) Harty and Roberts (1974)
No. of schools
8 4 2 2 1 1 1 1
of textbooks. For many questions a graduated response was used. Other questions required a choice of one or two alternative answers. Instructions for the completion of the questionnaire were as follows: a. Please answer as directly as possible. b. If a choice is provided, please give preferred answer. c. The following guidelines are suggested: Never Rarely Occasionally Frequently Generally Always
0 1 - 9 per cent 10 - 49 per cent 50 - 89 per cent 90 - 99 per cent 100 per cent
d. Please complete every question-do not leave blanks. Comments on the questionnaire were invited, for which a separate sheet was included. Individual schools were identified only by numbers. Questionnaires were also distributed to all staff within the Department of Prosthetic Dentistry at The London Hospital Medical College in an attempt to check whether there is a difference between what is actually taught and what the head of a department thinks is taught.
RESULTS Question 1 asked respondents to list recommended textbooks and department-produced texts (Table I). In addition to the books listed, eight other texts not directly concerned with partial denture construction were mentioned. Two schools made no response to either part of this question. One school answered that no textbooks were considered suitable and one replied that they used alI British and some American publications. Department-produced texts as hand-outs were used by nine schools. Questions 2, 3 and 4 related to the teaching of the use of study casts, whether these are articulated and whether the patient requiring partial dentures should be examined for possible disturbance of maxillomandibular relations (Table II). Questions 5 and 6 dealt with surveying, and the responses were as in Table III. Questions 8 and 9 dealt with tooth preparation. Seventeen schools teach tooth preparation as a standard procedure and one school gave a qualified affirmative response. The purposes
3
Barsby and Schwarz: Teaching of partial denture construction
Tab/a II. Use of study casts and maxillomandibular
Response Always Generally Frequently Occasionally Rarely Never
Use of study casts 15 1 2
Tab/e 111.Surveying of study and master casts
Response
Surveying of study casts
Surveying of mastercast
14 2 1 1
18
Always Generally Frequently Occasionally Rarely Never
relations Examination for disturbance of maxillomandibular relations
Articulated study casts 9 5 1 3
13 1 1 2
Tab/e IV. Purposes for which tooth preparation is Carried out No. of schools
Procedure Rest seat preparation Creation of guide planes Recontouring buccal/lingual shape Others
Tab/e VI. Requirement prescription of denture
Tab/e V. Stage at which records are made Stage For study casts Before casting is made After casting is made
occlusal relationship
No. of schools 18 12 13
Response Always Generally Frequently Occasionally Rarely Never
to
17 11 15 4
submit
full written
Before mouth preparation
As instruction to laboratory
13 3
14 3 1
2
for which tooth preparation is carried out are shown in Table IV. Additional purposes mentioned included ‘correction of anomalies’, occlusal correction, creation of undercuts, improving appearance and cleanability and creation of space. Question 10 sought to determine at which stage occlusal relationship records are made (Table V).
Question 11 related to making a written commitment towards denture design before mouth preparation and the subsequent instructions to the laboratory (Table VZ). Questions 12, 13 and 14 related to the place of other treatment in the treatment plan for the partially edentulous patient. Fourteen schools teach that periodontal treatment should be carried out before prosthetic treatment. Two schools allowed periodontal treatment to proceed concurrently and two schools provided periodontal treatment after prosthetic treatment. With regard to abutment tooth restoration, sixteen schools teach that this should
4
Journal of Dentistry, Vol. ~/NO. 1
Table VII. Use of special trays Response
Table VIII. Choice of impression materials No. of schools Material
Always Generally Frequently Occasionally Rarely Never
Primary impression
Master impression
17 1
17 7 7 3 3
Alginate Silicone rubber Mercaptan rubber Polyether rubber Composition
4
Table IX. Free end saddle dentures No. of schools teaching use of particular procedures
Response ~-
a
Always Generally Frequently Occasionally Rarely Never
4 3 1
Table X. Materials used for major connectors
Response Always Generally Frequently Occasionally Rarely Never
Cast metal P/ /P 2 5
a 2
2 11 2 2
Resin P/ 1 1 7 5 3
/P 1 1 3 1 11
Wrought metal P/ /P 1
3 15
1 3 7 6
be carried out with the partial denture design in mind. One school gave no response and one did not consider abutment tooth restoration from this viewpoint. Question 14 asked whether other departments considered abutment tooth restoration with a view to partial denture design. Almost every school gave a qualified affirmative response. Three schools did not think other departments paid sufficient attention to this. Questions 7 and 15 referred to the use of ‘special’trays and choice of impression material respectively. The responses are shown in Tables VZZand VZZZ. One school used composition as the only material for the primary impression. Schools which indicated the use of composition for the master impression also specified other materials, which were presumably used in combination. Two questions were included concerning free end saddle dentures. Question 16 asked whether particular procedures are taught as applicable for this type of denture and the results are shown in Table IX. Two schools did not respond to this question but did answer Question 17, which asked which procedures are employed. Nine schools teach the use of ‘stress-breaker’devices, and 15 schools teach the use of particular impression procedures.
Barsby and Schwarz:
Teaching
of partial denture
5
construction
. . b * . b ??
. .
.
. .
. .
b
??
L
1
2
3
4
5
6
Hours Fig. 1. Total average chairside time for dental school staff when treating a patient by provision of a partial denture.
Questions 18, 19 and 20 related to major connectors. The results are shown in Table X. For both cast metal and resin major connectors, one school gave a qualified response stating ‘wherever indicated’. Question 21 asked from which source students obtain patients. The replies indicated that most patients come directly to departments of prosthetic dentistry, followed in order of frequency by referrals from departments of conservative dentistry, periodontology and oral surgery. Two schools reported the use of a common waiting list for all departments. In Question 22 the respondent was asked to indicate the average total chairside time employed by himself or his staff when treating a patient by provision of a partial denture. The results are shown in Fig. 1. Some respondents indicated a range, one quoted time taken by students and one commented that no simple cases were treated by staff. Nine schools made written comments on the questionnaire, mostly in the form of explanatory notes in relation to particular questions. Some respondents pointed out possible ambiguities in the questionnaire and some suggested further topics on which questions might have been included. The intra-departmental questionnaires showed considerable agreement in the teaching of the staff in the one department of prosthetic dentistry examined in this way. DISCUSSION No one textbook of partial denture construction is used universally in the eighteen schools
surveyed. This contrasts with a survey of American dental schools by Bowman (1970) which showed that thirty out of forty-three schools investigated used McCracken’s Partial
6
Journal of Dentistry, Vol. ~/NO. 1
&nme Construction (Henderson and Steffel, 1973). Schools in the United Kingdom often used more than one text and many produce hand-outs and distribute photocopies of select-
ed Papers. Where members of a department had produced a textbook it was recommended. Thirty out of forty-three American schools required the use of a laboratory manual, whereas only one United Kingdom dental school specifically mentioned this. Study casts were almost universally accepted but slightly fewer schools taught the necessity to mount them on an articulator. These findings are at variance with the response to Question 4, since a higher proportion of schools always examine for disturbances of maxillomandibular relations but presumably this is only carried out clinically. Bowman (1970) reported that all of the American schools in his study used study casts and 75 per cent of them insisted that these be mounted on a semi-adjustable articulator. One school in the present survey, using composition primary impressions, always surveyed the resultant study cast. This is incompatible with the ability of the material to reproduce undercuts. The majority of schools teach the use of special trays. It may be that those who do not, teach the use of secondary impression methods such as the ‘altered cast’ technique of Applegate (1959). Question 17 confirms that special impression procedures for the free end saddle denture are widely taught, although it is not clear whether this is done routinely. The use of composition together with an elastomeric material suggests that some schools have a good selection of stock trays available and that these are modified, obviating the use of special trays. Tooth preparation is almost universally taught, and preparation of rest seats is the most common procedure. This contrasts with previously reported data from a survey of commercial laboratories specializing in cobalt-chromium castings (Schwarz and Barsby, 1977), which showed that only 4.6 per cent of 1853 casts had any evidence of tooth preparation. There was universal agreement for the use of occlusal relationship records at some stage of partial denture construction. The laboratory survey previously quoted showed that 40 per cent of casts sent to commercial laboratories for castings to be made were not accompanied by any indication of the occlusal relationship. All schools found it necessary to prepare either written instructions or a drawing of the denture design for the laboratory. This differs from previous findings in which only 36 per cent of work sent to commercial laboratories was accompanied by written or drawn instructions for the cobalt-chromium appliance (Schwarz and Barsby, 1977). Quinn (1971) commented that dental curricula appeared to be ineffective in teaching the use of dental laboratory personnel. He stated: ‘dentists are produced who not only cannot carry out laboratory work to the standard of a laboratory technician nor can they effectively instruct them’. Brown (1965) reported that in thirty-eight states (of the United States of America) dentists are required by law to provide written instructions for laboratory work and the work must only be carried out by the laboratory on receipt of written instructions from a licensed dentist. A survey of dentists’ opinions by the American Dental Association (1959) reported the responsibilities of a dentist with regard to ‘removable partial denture service’. The following items were considered desirable: accurate impressions for study casts; provisional survey and design; preparation of retentive, reciprocal, rest areas and guide planes; final impressions to be cast on dentists’ premises; final survey and design to the drawn on the cast; path of insertion to be marked; free end saddle areas to be reproduced by functional impressions; functional ‘chew-in’for jaw relationships.
Barsby and Schwarz:
Teaching
of partial denture
construction
7
With regard to the restoration of abutment teeth, there was universal consideration by United Kingdom departments of prosthetic dentistry for this to take account of the denture design, but a very qualified response with regard to the view of other departments. This suggests room for improved integration in teaching in most schools. Every school is aware of the problems of free end saddle dentures and all schools teach that special consideration should be given to this, the most common approach being the use of impression materials. Dental schools suggest the use of cast metal major connectors more commonly for lower partial dentures than for upper dentures. Resin major connectors are more commonly used for upper partial dentures than for lower ones. Wrought metal major connectors are used more frequently in the lower jaw than in the upper. The ratio of resin dentures to metal dentures provided within the General Dental Services is approximately 9 : 1 (Dental Estimates Board Annual Report, 1976). Within dental schools the commonest range of time taken by staff for the clinical stages of partial denture construction falls in the range 2-3s hours. Clinical time is important because it indicates the cost of procedures. The cost of partial denture construction by heads of departments of prosthetic dentistry could be between g20 and ti0 if based on a value for practice clinical time within the National Health Service of &l 1 per hour (British Dental Association, 1978). The laboratory cost for partial dentures varies between 225 and ti0, comprising &15-a0 for the cobalt-chromium framework and approximately &lo for the other stages. The total cost for clinical and laboratory work would therefore range between &45 and 035. This contrasts markedly with the current fees allowed within the National Health Service General Dental Services (1976) where the total fee allowed for metal-based partial dentures ranges between 229 and g32 inclusive of laboratory fees. After deduction of laboratory fees, the NHS fees represent a maximum outlay of time on the part of the practitioner of half an hour. More complex appliances would therefore require an investment of time given gratuitously. It is clear that dental schools in the United Kingdom cannot train students to provide partial dentures at the speed required for the rate of remuneration they are likely to encounter in practice. Future reviews of the NHS fee structure for partial denture treatment must remedy this unsatisfactory situation.
Acknowledgements We would like to thank all heads of departments who participated in the survey and the staff of our own department who also completed questionnaires and offered advice on the preparation of this paper. We are indebted to Miss E. Brand for secretarial assistance and to Mr G. Walter for photographic services. REFERENCES
American Dental Association (1959) Survey of dentist opinion III. Dental drugs; dental laboratories; reciprocity. J. Am. Dent. Assoc. 59, 512-5 17. Applegate 0. C. (1959) Essentials of Removable Partial Denture Prosthesis, 2nd ed. Philadelphia, Saunders, pp. 230-256. Bates J. F. (1978) Removable Partial Denture Construction, 2nd ed. Bristol, Wright. Bowman J. F. (1970) Removable partial prosthodontics: comparison surveys-1964 and 1969. J. Dent Educ. 34,93-97.
Journal of Dentistry, Vol. ~/NO. 1
8
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