Teaching of direct composite restoration repair in undergraduate dental schools in the United Kingdom and Ireland

Transcription

1 European Journal of Dental Education ISSN Teaching of direct composite restoration repair in undergraduate dental schools in the United Kingdom and Ireland I. R. Blum 1, C. D. Lynch 2 and N. H. F. Wilson 3 1 Restorative Dentistry, University of Bristol Dental School and Hospital, Bristol, UK, 2 Tissue Engineering and Reparative Dentistry, School of Dentistry, Cardiff, UK, 3 Restorative Dentistry, King s College London Dental Institute, London, UK Keywords teaching; composite restoration; repair; minimally invasive; dental students. Correspondence Dr Igor Blum Department of Oral and Dental Sciences University of Bristol Dental School and Hospital Lower Maudlin Street Bristol BS1 2LY, UK Tel: + 44 (0) Fax: + 44 (0) i.blum@bristol.ac.uk Accepted: 18 November 2010 doi: /j x Abstract Aim: To investigate aspects of the teaching of restoration repair as a minimally invasive alternative to the replacement of defective direct composite restorations in teaching programmes in undergraduate curricula in dental schools in the United Kingdom and Ireland. Methods: An online questionnaire which sought information in relation to the current teaching of composite restoration repair was developed and distributed to the 17 established UK and Irish dental schools with undergraduate teaching programmes in Spring Results: Completed responses were received from all 17 schools (response rate= 100%). Fifteen schools reported that they included teaching of repair techniques for defective direct composite restorations in their programme. Of the two remaining schools, one indicated that it would introduce teaching of repair techniques during the next five years. The most common indication for a composite repair was that of tooth substance preservation (15 schools). The defects in restorations considered appropriate for repair rather than replacement by the largest number of schools included partial loss of restoration (13 schools) and marginal defects (12 schools). The most commonly taught surface treatment when performing a repair was mechanical roughening of the existing composite with removal of the surface layer (14 schools). Thirteen schools taught etching and the application of an adhesive bonding agent to the prepared surfaces, while the most commonly taught material for completing the repair was a hybrid composite resin (12 schools). Popular finishing implements included diamond finishing instruments (13 schools) and finishing discs (11 schools). Conclusion: Not withstanding reluctance amongst general dental practitioners, the teaching of repair of a defective composite restoration, rather than total restoration replacement, is firmly established within UK and Irish dental school programmes. Repair techniques have clear advantages for patients, not least including a minimally invasive approach to treatment and avoidance of unnecessary loss of tooth tissue and pulpal damage. Dental practitioners should look more to repair techniques when managing defective composite restorations and clinical dental teachers should continue to research and refine composite repair techniques. Introduction Dental practitioners face two principal challenges when addressing the operative dentistry needs of their patients. These are the early detection and minimally invasive treatment of primary dental caries and other diseases of the teeth, and the maintenance of existing restorations in their patients (1). In the United Kingdom, in particular, a special problem is that of managing those patients who received many large and extensive amalgam restorations in the 1960s, 1970s and 1980s, who were referred to in a recent governmental report as the heavy metal generation (2). In the subsequent 20 years, there has been an e53

2 Teaching of direct composite restoration repair Blum et al. increasing realisation of the need for minimally invasive techniques; however, amalgam continued to be the material of choice for the restoration of posterior teeth in dental school curricula (3 7) and even now still predominates in UK dental practice (8, 9). This is despite evidence to demonstrate the comparable longevity of posterior composite and amalgam restorations (10, 11), as well as the clear advantages of composite resin materials in terms of aesthetics, patient preference, biomechanical considerations and opportunities to refurbish and repair rather than replace. Driven by the philosophy of minimally invasive dentistry, an increasing evidence-base to favour the placement of posterior composite restorations and the changing nature of the presentation of dental caries, current dental students in the United Kingdom and Ireland are practising a much less invasive form of clinical intervention than previous generations of students, including the placement of more posterior composite restorations than amalgam restorations (12). On average, the present split between posterior composite and amalgam restorations in UK and Irish dental school is 55:45 in favour of posterior composite restorations (12). This has the potential to change the practice of operative dentistry over the coming years. Notwithstanding the above, there are lingering doubts and suspicions surrounding the clinical performance of composite restorations in posterior teeth. Furthermore, despite evidence from the mid-1990s that a major advantage of posterior composite restorations is their repairability (13, 14), many practitioners remain of the view that the presence of superficial defects and marginal staining necessitates the removal of a posterior composite restoration and the provision of a new, typically larger restoration (15, 16). This decision is often flawed: the presence of marginal defects and staining in association with a posterior composite does not always mean that the restoration requires total replacement (17). Such decisions are rooted in a bygone era of excessive intervention, tempered by mechanistic rather than biological approaches to the management of defects in restorations and to a time when restoration repair was at best considered to be a temporary measure, pending proper operative management. Restoration repair involves the removal of part of the restoration giving cause for concern, be it a deficient margin or interfacial staining (18 20). The prepared restoration and tooth surfaces may require careful finishing followed by chemical surface treatment, including acid etching and the application of a dental adhesive to enhance the interfacial bonding, prior to repair placement (21 25). Long-term in vivo clinical studies such as those of Gordan et al. (18) have demonstrated that repair techniques offer viable and non-destructive alternatives to total restoration replacement. In effect, the utilisation of appropriate repair and refurbishment techniques increases the longevity of the affected restoration whilst limiting the extent of any necessary operative intervention and increasing the chances of the restored tooth being one of patient s teeth for life. Evidence from the period demonstrates that the teaching of composite restoration repair had entered into dental school teaching programmes and that a considerable number of dental students were gaining experience in restoration repair techniques prior to graduation (26 29). In consideration of recent advances in materials technology and the drive towards the principles of minimally invasive dentistry, the aim of the present study was to examine the current teaching of direct composite restoration repair in dental schools in the United Kingdom and Ireland. Materials and methods The person identified as being responsible for the delivery of operative dentistry teaching programmes within the 17 established dental schools in the United Kingdom and Ireland was contacted by in Spring 2010 and invited to complete an internet-based survey (Bristol Online Surveys, Bristol, UK) on the teaching of direct composite restoration repair in their dental school. The information sought included: l the teaching of composite restoration repair techniques in their dental school programme; l the nature of this teaching; l the reasons for including this teaching; l clinical indications for repair; l l views on the longevity of composite restoration repairs; techniques taught for composite restoration repair. Question designs included both open and closed styles: in the former, respondents were given some space in which to write a textual response, whilst respondents were given a number of possible responses to a statement and asked to identify the most appropriate in the latter. Non-respondents were followed up by . Information received was analysed using the Bristol Online Surveys software. Descriptive results are reported. Results Completed responses were received from all 17 schools (response rate = 100%). Extent and nature of teaching Fifteen schools indicated that they included the teaching of repair of direct composite restorations in their dental school programmes. Of the two schools currently not teaching this technique, one school indicated that they did not include this teaching given a lack of available time within their dental school curriculum. They did report, however, that they hoped to introduce this teaching over the coming 5 years. The other school noted that it did not intend introducing this teaching, given poor experiences with composite repairs and concerns about the possible presence of recurrent caries under the affected restoration. Of those schools teaching the repair of direct composite restorations, their reported reasons for doing so were as follows: Clinical experience Existing evidence Information from case reports 12 schools 7 schools 2 schools e54

3 Blum et al. Teaching of direct composite restoration repair Free text responses were invited and included: l Technique makes common sense lack of evidence for replacing entire restoration. l Minimise the increase in cavity size so slowing restorative spiral. l We try to promote minimal intervention. Nine schools that included teaching of the repair of direct composite restorations in their dental school curricula reported that this teaching was based on ad hoc clinical experience in student clinics. Seven schools reported that they included formal didactic teaching on this subject, which was followed up with clinical experience. One school reported that their teaching was didactic only with no clinical experience. Indications for repair The most commonly reported indications for the teaching of the repair of direct composite restorations were tooth substance preservation (15 schools) and reduced risk of harmful effects on the pulp (10 schools). Other indications included reduction in treatment time (five schools) and reduced costs to the patient (two schools). Respondents were then asked to indicate which defects in restorations were appropriate for repair rather than replacement of direct composite restorations. The responses are summarised in Table 1. The defects in restorations considered appropriate for repair rather than replacement by the largest number of schools included partial loss of restoration (13 schools) and marginal defects (12 schools). The defects in restorations considered appropriate for repair rather than replacement by the least number of schools included an isthmus fracture of a posterior direct composite restoration (two schools) TABLE 1. Teaching of restoration-related failures considered appropriate for repair rather than replacement of direct composite restorations (maximum possible number of responses = 15) Restoration-related failure Secondary caries 6 Marginal defects 12 Marginal discolouration 11 Superficial/surface colour correction 11 Restoration discolouration labial/buccal 10 Restoration discolouration occlusal 7 Restoration discolouration cervical 8 Restoration discolouration proximal 4 Discolouration involving more than one surface 5 Partial loss of restoration 13 Abrasion/attrition/erosion 8 Bulk fracture of an anterior restoration (incisal) 6 Bulk fracture of an anterior restoration (proximal) 6 Bulk fracture of an anterior restoration (proximal-incisal) 5 Bulk fracture of a posterior restoration (occlusal) 5 Bulk fracture of a posterior restoration (isthmus fracture) 2 Bulk fracture of a posterior restoration (box fracture) 7 Bulk fracture of a posterior restoration (marginal ridge 5 fracture) Number of schools TABLE 3. Techniques taught for the repair of direct composite restorations Surface treatments of existing composite restoration Mechanical roughening of existing composite with 14 removal of exposed surface Acid etching with phosphoric acid 11 Cleaning with slurry of pumice 7 Aluminium oxide air abrasion 3 Acid etching with hydrofluoric acid 1 No mechanical surface treatment 0 Materials utilised in the repair technique Dentine/enamel bonding agent 13 Silane coupling agent 5 Hybrid composite 12 Flowable composite 5 Nanohybrid composite 4 Glazing resin 2 Finishing techniques for the placed repair Diamond finishing instruments 13 Finishing discs 11 Composite polishing points 8 Composite polishing paste 7 Tungsten carbide finishing instruments 3 and discolouration on the proximal surface of a restoration (four schools). Respondents were then presented with some clinical scenarios involving the fracture of tooth tissue adjacent to an existing direct composite restoration and asked to indicate which scenarios they considered appropriate for repair. Responses are summarised in Table 2. The most commonly agreed scenario considered appropriate for repair rather than restoration replacement was a cusp fracture in a posterior tooth restored with a direct composite restoration (14 schools), whilst the least commonly agreed scenario for repair was a posterior cracked tooth (seven schools). Clinical techniques Number of schools Techniques taught for surface treatments of existing direct composite restorations and the materials selected for use in repair and finishing techniques are summarised in Table 3. The TABLE 2. Teaching of clinical scenarios involving tooth fracture adjacent to existing direct composite restorations considered appropriate for repair rather than replacement of direct composite restorations (maximum possible number of responses = 15) Restoration-related failure Posterior tooth (cusp fracture) 14 Anterior tooth (tooth fracture from incisal region) 11 Anterior tooth (tooth fracture from proximal region) 11 Anterior tooth (tooth fracture from proximal-incisal region) 10 Posterior tooth (cracked tooth) 7 Number of schools e55

4 Teaching of direct composite restoration repair Blum et al. most commonly taught surface treatment was mechanical roughening of the existing composite restoration, including removal of the surface layer of material (14 schools). Thirteen schools taught the application of an adhesive bonding agent to the prepared surface. The most commonly taught material for completing repairs was a hybrid composite resin (12 schools). Popular finishing devices included diamond finishing instruments (13 schools) and finishing discs (11 schools). Patient acceptance and treatment outcome Thirteen schools reported that they found patients willing to accept composite restoration repairs as an alternative to restoration replacement. The other four schools did not respond to this question. Respondents were asked to indicate what they considered to be the acceptable longevity of a repair to an existing composite restoration. Responses were received from eight schools. Their responses were as follows: <3 years 1 school 3 5 years 2 schools 5 years 2 schools 5 10 years 3 schools Only five schools, however, monitored repaired composite restorations as part of a recall system. Of these, three schools estimated that repairs increased the longevity of the direct composite restoration by 30% and two schools estimated that repairs increased longevity of the repaired restoration by 50%. Discussion Stemming from the development of adhesive dental technologies and, amongst other factors an increased understanding of dental caries, minimally invasive approaches should increasingly replace traditional forms of treatment (30). In the context of the present paper, minimally invasive dentistry offers substantial benefits to, in particular, patients with teeth restored by means of direct composite restorations. In reporting the findings of the present study, the limitations of data collection by means of a survey, albeit with 100% response, are fully acknowledged. To minimise these limitations, great care was taken in the preparation of the survey questionnaire to avoid ambiguous and otherwise misleading questions, most of which had been tested and found to be fit for purpose in related studies. Circumstances precluded repeat surveying to test reproducibility, and no attempts were made to collect data from other than the person identified as being responsible for the delivery of operative dentistry teaching within each school to assess commonality of views within each school. The results of the present survey indicate that the teaching of the repair rather than total restoration replacement of direct composite restorations is well established in dental school curricula in the United Kingdom and Ireland, as supported by both in vitro (21 25) and in vivo (18 20) studies. In contrast, there is evidence to suggest that the technique is not readily accepted in e56 UK general dental practice (15), with some evidence to indicate that recent dental school graduates are positively disposed to restoration repair techniques at the outset of vocational training, but less likely to do so following completion of this training (16). The reasons for the reluctance to accept such new techniques amongst practitioners are cause for concern. Previously, reasons were linked to funding arrangements under the NHS contract, in particular, under the old contract in which a specific fee item did not exist for composite restoration repair (16). Under the new contractual arrangements, there is no justification for not undertaking restoration repair procedures. The preference for restoration replacement rather than repair could also be a manifestation of defensive dentistry and a fear of comeback, possibly even litigation based on a possible failure to identify the presence of caries at the time of managing a defective restoration. The practice of defensive dentistry, however, runs the risk of allegations of excessive intervention. This divergence in clinical practice is another example of a disconnect between evidencebased dental school teaching and best practice and subsequent behaviour in independent practice previous examples having been noted in relation to removable partial denture design (31), the appropriate use of rubber dam (32, 33) and a reluctance to embrace minimally invasive posterior composite restoration techniques in preference to more destructive amalgam techniques (12). Such examples of differences in approach in dental school and clinical practice leave, most importantly, patients confused, and may lead to tension in the profession, exemplified by complaints that students are not suitably prepared for dental practice where circumstances may tend to favour continuation of traditional custom and practice rather than change to so-called ivory tower techniques. Basing more teaching in primary care settings with the involvement of astute dental clinicians, promotion of evidence-based practice and further developments in continuing professional development are some of the means whereby apparent disconnections between dental schools and general practice may be addressed (34). Reportedly, one of the most common reasons for choosing total restoration replacement rather than repair is a fear that caries may be present under the remaining part of the restoration (35). It is apparent from the work of, for example, Mjör and Toffenetti (17) that caries developing in relation to existing restorations is typically a new lesion in the remaining tooth tissues adjacent to the margin of the restoration. Under such circumstances, a localised repair technique is appropriate, assuming the existing composite restoration/tooth interface is investigated and the remaining tooth tissues being cut back in the region of the new caries to render the tooth tissues and remaining part of the restoration caries free. Unless the investigation of the composite restoration/tooth interface reveals additional difficulties, in particular caries penetrating below the remaining part of the restoration and in the absence of any special considerations, a repair should be indicated rather than further intervention to replace the restoration. In this way, minimally invasive techniques offer a viable alternative to restoration replacement and prolong the lifetime of the restoration whilst limiting unnecessary tooth tissue loss and pulpal trauma (19, 20). Clinical techniques described in the survey responses for direct composite restoration repair were in the main, in keep-

5 Blum et al. Teaching of direct composite restoration repair ing with current best available evidence. Laboratory-based studies indicate that some form of mechanical roughening of the exposed composite restoration surface is appropriate prior to the application of the repair composite material (21, 36, 37). This technique was taught in 14 of the 15 schools teaching composite restoration repair techniques. Etching and bonding of the exposed tooth and composite resin surfaces is indicated when performing a repair, as is associated with increased bond strength between old and new composite (21 25). This technique was taught by 13 of the schools. It is of special note that five of the 15 schools taught composite restoration repair techniques involving the application of flowable composite materials to repair sites. Whilst flowable materials offer advantages, including ease of placement, they have a low filler loading. As such, flowable composites suffer relatively high polymerisation shrinkage and surface porosity (38) and, as such, should be applied away from margins and in thin section increments, possibly to help wet the internal features of the repair preparation with composite resin. Findings from recent studies (18, 19) indicate that repair procedures of defective composite restorations extend the longevity of the affected restoration. As such, there is much to commend repair techniques in modern clinical practice in which the 10-year survival of direct restorations is less than 60% (39) and the costs associated with unnecessary restoration replacement place significant economic burdens on patients and third-party providers of oral healthcare, notably the NHS in the United Kingdom. Concluding remarks This study has demonstrated that the teaching of the repair of defective composite restorations, rather than their replacement, is well established in dental school teaching programmes in the United Kingdom and Ireland. Such teaching is to be welcomed and encouraged as it is in the best interests of patients, minimising unnecessary loss of tooth tissue and limiting pulpal trauma. There is evidence, however, that such techniques are not routinely applied in general dental practices in at least the United Kingdom. The results of the present survey as well as recently published long-term clinical outcome data will encourage dental practitioners to review their current clinical techniques to expand their practice of modern minimally invasive and evidence-based operative dentistry. 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