Curricula for the teaching of complete dentures in Spanish and Portuguese dental schools

Objectives: Given the need to ensure that dentists are sufficiently skilled to offer the best possible care to their patients, this study aims to evaluate the teaching methods and clinical experience achieved by undergraduate dental students in Spain and Portugal as regards complete dentures. Study design: In February 2011, a questionnaire seeking information about the preclinical and clinical teaching of complete dentures was e-mailed to all Spanish and Portuguese dental schools with fully developed undergraduate degree dental programs. Results: A response rate of 82.6% was obtained. The distribution of lectures and hours spent at the laboratory and in clinical activities revealed that teaching complete dentures is eminently a practical issue, this being mostly performed by full-time prosthodontists. All surveyed schools teach the design of the record base, and most of them instruct students in the mounting of teeth in wax. Most schools (94.7%) used a semiadjustable articulator, alginate for primary impressions (73.7%) and elastomeric materials in border-molded custom trays for final impressions (68.4%). In most schools, within the clinical setting students work in pairs, the mean student/ professional staff member ratio being 2.3 ± 0.7. Most schools perform a competence-based assessment (83.3%), although innovative techniques such as problem-based learning are still rarely applied. On average, the students emplaced 1.8 ± 1.2 complete dentures during their clinical training, ranging from 0 to 4, although no clear trend was seen as regards the minimum number of dentures to be made for graduating. Conclusions: Variations in teaching programs and clinical experience concerning complete denture curricula among Spanish and Portuguese dental schools are evident, but all the schools base their teaching mainly on preclinical and clinical practice. However, the low number of dentures made by student per year seems insufficient to ensure clinical skills and cope with social needs. Key words:Dental education, questionnaires, complete dentures, curricula.


Introduction
In 1970 Sharry (1) reported that: "there is some agitation and considerable concern over the fact that prosthodontics in dental school curricula is diminishing somewhat in its importance, and that a few dental school administrators believe that complete and partial edentulousness will disappear from the scene within the passage of a decade or two." However, the need for prosthodontic care could increase for decades in developed countries due to the increasing life expectancy among the elderly and because current denture-wearers require periodic check-ups and replacements. This means that knowledge and skills in treating patients with edentulism will become increasingly important as the century progresses (2). Clark (3) suggested that edentulous patients could be divided into two main groups: those who can cope with dentures and those who have some difficulty. He also stated that "the undergraduate curriculum should aim to equip graduates to treat the first group properly and attempt to recognise the second group and refer them for specialist care". Thus, dental schools must continually evaluate the curriculum as regards the construction of removable dentures in order to ensure that the dental health needs of society at large are being met. It was also predicted that the number of students in dental schools would decline as the 21st century progressed. However, in Spain the number of dentists is in fact growing exponentially (4). It should be noted that operative dentistry and prosthodontics continue to be the two largest areas in dentistry (5), even in the current graduate curricula in dentistry within the European Higher Education Context. Despite this, since the sixties there has been a gradual reduction in the curricular time devoted to the teaching of both the clinical and technological aspects of complete denture (henceforth CD) construction (5). To a certain extent these changes could reflect changes in population trends and treatment requirements. In light of the need to ensure that dentists will be sufficiently skilled to offer the best possible care to their patients and for monitoring the baseline clinical competences among European countries according to the recent mandatory implantation of the Bologna Accord for Convergence in Higher Education in the European Union (settled for the academic year 2010-2011), the present study aims to evaluate the current situation regarding teaching methods for CD construction in Spain and Portugal and to determine which educational techniques and materials are currently used, before the implantation of the Bologna System. To date only U.S (6) and British Dental Schools (7) have been evaluated in terms of CD curricula, and there is a clear need of monitoring dental curricula within European countries for convergence reasons. The purpose of this study was to investigate the current situation regarding the teaching of CD construction in Spain and Portugal and to determine which educational techniques and materials are currently in use at the various dental schools (before the implantation of the Bologna System).

Material and Methods
In February 2011, a questionnaire was sent by e-mail to the chairperson identified as being responsible for the course in CD construction at each of the 23 dental Schools in Spain and Portugal. The questionnaire was designed to capture information concerning the curri-cular content of the teaching of CD for undergraduates before the implantation of the Bologna System. Following a second mailing to schools that had not replied to the initial attempt within two weeks, 19 of the 23 dental Schools (16 Spanish schools: 11 public and 5 private; and 7 Portuguese: 3 public and 4 private schools) responded, affording a response rate of 82.6%. The questionnaire consisted of 22 items, and asked the respondents to specify several teaching aspects of their CD programs. Some questions were open, to acquire both quantitative and nominal data with freedom, while others were closed in either a dichotomous or in a multiple-choice format. However, even within these items, the option of providing a specific answer other than the choices listed was also available for some questions. The questions (Q) were pilot-tested by members of dentistry schools of both countries with experience in this field, who approved the questionnaire before it was mailed. Data were imported to SPSS v.18 for Windows (SPSS Inc, Chicago, IL), and descriptive statistical procedures were carried out to summarize the information.

Results
All schools still include CD teaching in their curricula, but there are considerable variations in the experience actually gained by students. The responses distribution to the questionnaire is summarized in tables 1, 2 and 3.
-Preclinical teaching Q1: Preclinical course of tooth mounting and the design of prostheses. Seventeen schools (89.5%) reported that they systematically performed this kind of laboratory teaching in The student-staff member ratio for clinical sessions was on average 10.6 ± 6.9 students, the range being between 5 and 30 students. In 14 schools (82.4%: a valid percentage since two schools did not respond), students work in pairs; in one school they work in threes, and in two schools 4 students work in the same box. The mean ratio for clinical activity was 2.3 ± 0.7 students/staff member. Eighteen schools responded to this question (94.7%). Half of them declared that they had pre-recorded video demonstrations available for their students on the internet.

Discussion
The results of this survey demonstrate the broad variety in the ways of the teaching of CD among Spanish and Portuguese universities before the implantation of the Bologna System, although several trends in the materials and procedures used are detected. The main coincidence is that all the schools surveyed teach the design of the record base on the plaster model. Also, most schools (89.5%) have a preclinical course of tooth mounting and denture design, mainly implemented during the third academic year of their respective courses (73.7%). This preclinical course is widely applied in both U.S. (6) and British Dental Schools (7), but in contrast to our results the majority of British Schools teach CD in the 4th and 5th years of their degree courses (7). Furthermore, our results demonstrate that the use of a manikin head for preliminary impressions in laboratory teaching is more widespread than in U.S. schools (6), although comparable to the situation in British schools (7). In terms of quantitative teaching, the distribution of hours dedicated to lectures, laboratory work and clinical activities reveals that the teaching of CD is eminently a practical issue (Table 1: Q3). The theoretical background is mainly conveyed through lectures or seminars, the use of innovative techniques, such as problem-based learning, and the use of online lectures (Table 1: Q4) being exceptional, in agreement with Rashedi et al. (6), even though these techniques have proven effectiveness for students (8). However, it does appear that a virtual teaching is partially used for video demonstrations and uploading lectures (Table 3: Q22). According to Rashedi et al. (6), the overall mean of laboratory hours in preclinical courses among U.S. dental Schools is 74 hours, ranging from 31.5 to 160, which doubled the results of the present study. Castillo de Oyagüe et al. (9) reported that the duration of the preclinical course for removable partial dentures is clearly shorter in Spain, in comparison with U.S. and Great Britain. However, the mean number of lecture hours reported for U.S dental schools (6) (28 hours, ranging from 12 to 80) is similar to what was observed here. Our findings also seem to be in agreement with those reported by Sukotjo et al. (8) , referring to the preclinical hours spent on prosthetics implemented at the Harvard School of Dental Medicine. Starting in 1970, some authors have documented the broad variations in student/professional staff ratios in Dental Schools (ranging from 1:3 to 1:33) (10). The student/staff ratio in clinical teaching found in the present survey (Table 1: Q5) is similar to those reported for U.S. dental Schools (6,8), most of which have a ratio of 8:1 or higher, with an overall mean of 12:1. These results ( Table 1: Q5) are also fairly similar to those reported for British dental schools, ranging from 6 to 12 students per member of the professional staff (7). Nevertheless, these ratios are less than ideal, since the paired teaching (one student acting as the dentist and the partner as the assistant) reported by most of the schools surveyed (Table 2: Q13) reduces the time available for individual students to gain hands-on experience. On the other hand, it is not convenient for a dentist to work alone, and hence a pair-based system could improve students' team-working abilities. McGiveny (11) recommended a preclinical ratio of 1:10, and a clinical ratio ranging from 1:4 (first year) to 1:6 (for fixed and removable prostheses). Accordingly, the ratios reported here are slightly higher than this recommendation. The percentage of full-time prosthodontists supervising CD teaching is similar to that reported by Rashedi et al. (6) for U.S. schools, and is perhaps one of the strengths of our traditional CD teaching. However, it is noticeable that full-time prosthodontists are mainly involved in theoretical teaching (84.2%) instead of in practical teaching (63.2%). This finding may be explained since in preclinical and clinical teaching several groups of student works simultaneously, each supervised by one member of the professional staff. However, in theory lectures there is only a single group, and this activity is mainly covered by full-time prosthodontists. In terms of materials and procedures, most programs (95%) report using a semi-adjustable articulator and teaching jaw manipulation tests to establish the mandibular centric relation and eccentric records in order to customize the parameters of the articulator. The proportion of schools teaching a custom setting of semiadjustable articulators instead of using average parameters is surprisingly high (  (7) for British schools, although there is a certain tendency to use silicones or polyether as the primary option, as reported Petrie et al. (13) for U.S. prosthodontists and dental schools. Nevertheless, in contrast to these authors (13), who reported a large proportion of prosthodontists using polysulfides for working impressions, among the Spanish and Portuguese schools surveyed polysulfide is not used. Furthermore, most schools use custom trays for final impressions, although the percentage is lower than that reported among U.S. Schools (98%) (12). Most Spanish and Portuguese schools mold the border tray using plastic compounds, as reported elsewhere (13,14). Elastomeric impression materials have also been reported as alternative materials for border molding (13). It is noteworthy that although the Bologna Declaration Agreement has only been introduced recently, and this system has not already affected to the subject of Prosthodontics, most schools do apply a uniform system of competence assessment, and most of them include an evaluation of clinical or preclinical skills in their final examination ( Table 2: Q16). Dentists in general and prosthodontists in particular, base their teaching on clinical practice, (Table 1, Q3), affording newly graduated students a reasonably adequate professional training to enter the job market. However, this clinical evaluation has traditionally been based on the tutor's continuous assessment of the gradual acquisition of clinical skills, and currently tutors have been called on (i.e., from the Bologna Accord) to standardize the minimum skills or procedural requirements to ensure the acquisition of professional competence. In this sense, we observed that there is no agreement about the minimum number of CD that students should make before graduation ( Table 2, Q17). Some reports indicate that most U.S schools establish a minimum of CD to be completed, but no official numbers have been published (12). In Great Britain, it has been suggested that students treating 6 or more edentulous patients would be adequately equipped for CD construction in vocational training (3). None of the schools surveyed reach this level, and thus authors consider that nowadays our students are not adequately skilled to treat edentulous patients by their own and without supervision. In addition, the mean number of CD constructed by each student per year in the present study (1.8 ± 1.2) seems to be insufficient to ensure adequate clinical skills. Clark et al. (3) pointed out this gradual decline in British dental schools. In any case, with this situation, recent Spanish and Portuguese graduates will be doomed to follow postgraduate courses to be instructed in this field, or to derive patients to trained prosthodontists. Current evidence suggests that there will be a need for CD to be made in Spain (15) for decades. To our knowledge no epidemiological studies have been car-e114 ried out in Portugal reporting data concerning edentulism in the elderly (16,17) but a similar pattern to that found in Spain would be expected. The data from the last national dental survey in Spain (15) revealed that the prevalence of CD wearers among the elderly has declined from 21.5% in 2000 to 15.6% in 2006. Moreover, the needs for CD in this latter survey were 4% and 5% in the upper and lower jaws of the elderly respectively. This need for CD will gradually decrease, but it is foreseen that, in general, cases will become more difficult since the supporting oral tissues and tolerance to dentures are reduced with aging (18). The present study highlights the main descriptors of the teaching of CD in Spain and Portugal, although this is only based on the perceptions of instructors. Thus, there is clearly a need to contrast this information by incorporating the views of trainees and this should be addressed in future studies.