Studies have reported a high frequency of iatrogenic damage since it was first noted in association with Class II cavity preparations in the 1970’s. The utilisation of protective devices such as stainless steel matrix bands was recommended by multiple studies, but rarely exercised by dental practitioners. A consequence is unnecessary placement of restorations in a previously healthy tooth, due to caries development in the defect or inappropriate diagnosis of the radiolucency on dental radiographs.
The research for this thesis was divided into two phases. The first phase extended knowledge gained from previous studies on the frequency and extent of iatrogenic damage to the contemporary situation. This phase commenced with an in vitro study that assessed the extent of the clinical problem, the outcome of which confirmed the need to manage it. The relevance of utilisation of plastic typodont teeth for investigating iatrogenic damage was examined. The second phase was dedicated to the development of a model for management of iatrogenic damage. Further in vitro studies were conducted to establish the effectiveness and feasibility of the proposed management model.
The proposed model for the management of iatrogenic damage included: i) prevention of occurrence and minimisation of iatrogenic damage by utilisation of protective devices; ii) the effectiveness of clinical techniques for detection of residual damage occurring in spite of the use of protective devices; and iii) possible methods for mitigation of the consequences of residual damage through the application of a protective coating.
The first in vitro study investigated the impact of various variables on frequency and extent of iatrogenic damage to approximal tooth surfaces during Class II cavity preparations, and the effectiveness of protective devices in minimising damage. A total of 10 experienced dentists and 10 senior students each prepared 24 Class II cavity preparations in typodont teeth without protection, 10 utilising protective stainless steel bands and 10 utilising novel protective wedges. The clinical relevance of the results was tested in a separate investigation that established a relationship in the depth of damage caused by a high-speed diamond bur on typodont versus natural teeth. The frequency of iatrogenic damage inflicted without the use of protective devices was in agreement with the results of previous studies, and the use of protection statistically significantly reduced the occurrence and depth of damage.
The most effective method of reducing iatrogenic damage is prevention. However, before a recommendation for the use of matrix bands and wedges could be made, it was necessary to investigate potential risks or undesirable effects associated with the use of protective devices. The literature review found no information on this topic. Therefore, a study was conducted to test the hypothesis that protective devices impair direct vision of the cavity, resulting in greater destruction through wider and deeper cavity preparations. Further, the preparation time for operators utilising protective devices was examined to assess for a reduction in operator efficiency. 120 Class II cavity preparations on first molars prepared by students and experienced dentists with and without protective devices were examined. There was no significant difference in cavity preparation width or depth for the variable of operator experience, and likewise for the use of stainless steel bands or wedges. Furthermore, there was no increase in cavity preparation time when protective devices were used.
The third study investigated operators’ ability to detect iatrogenic damage caused to adjacent teeth during routine Class II cavity preparations, as well as the possibility of protecting damaged surfaces by coating with a low-viscosity nano-filled adhesive resin. Some 17 second year dental students and 10 experienced dentists examined 5 sets of typodont teeth in phantom heads for iatrogenic damage. Further, 10 natural teeth with varying types of iatrogenic damage were coated with adhesive resin and the defects imaged using SEM. Both experienced dentists and students were able to detect the presence of iatrogenic damage in approximately 80% of cases. However, experienced dentists were significantly better than students in classifying the type of damage. The low-viscosity dental adhesive resin uniformly coated shallow to moderate defects.
A number of recommendations can be made on the basis of these investigations. Firstly, the potential benefits of the use of protective devices in prevention of iatrogenic damage during Class II cavity preparations outweigh the commonly perceived disadvantages to operators and patients, none of which are shown to be valid in this study. Consequently, this study supports the general clinical use of protective devices, particularly in teaching clinics. Secondly, the results stress the need to raise awareness of the potential for iatrogenic damage and to remind clinicians of its consequences. Thirdly, due to the high detectability of iatrogenic damage, it is recommended that practitioners proactively mitigate the risks associated with untreated iatrogenically damaged teeth by examination of potentially damaged surfaces. Coating of fresh iatrogenic defects with an adhesive resin may be a viable clinical option.