The presence of defective restorations or restorations with the clinical diagnosis of secondary caries is one of the most frequent problems encountered by general practitioners today. The diagnosis is inconsistent among dental practitioners and often does not rely on objective criteria. If in doubt, most general dental practitioners choose replacement as opposed to options of non-surgical treatment, including systematic restoration monitoring. Restoration replacement is especially common for restorations not originally placed by the evaluating practitioner. A dental practice-based research study involving 197 clinicians from the USA and Scandinavian countries, and close to 10,000 restorations, indicated that practitioners chose replacement over repair of defective dental restorations in over 75% of cases. The same study confirmed that practitioners who did not place the original restoration were more likely to replace it than practitioners who did.
In summary, replacement of restorations constitutes over 50 per cent of the work performed by general dental practitioners in their practices and it has contributed to the perpetuation of the “Repeat Restoration Cycle”. Consequently, the diagnostic finding ‘defective’ for an existing restoration is a critical step in treatment planning and it invariably affects the longevity of the restored tooth.
Secondary caries and staining of the margins of existing restorations are the most commons reasons for restoration replacement in permanent and primary teeth. Without objective criteria, it is difficult to differentiate secondary caries from marginal staining clinically. Despite the fact that some studies have associated microleakage with secondary carious lesion formation, the majority of the evidence demonstrates no relationship between the development of secondary carious lesions and the size of the leakage or gap alongside a restoration, except in cases in which the crevice exceeds 400 µm. Although the criteria for the diagnosis of a defective restoration may be based solely on visual and tactile examination, the subsequent management plan for this restored tooth should be based on the caries risk assessment of the patient as well.
When is repair or replacement required?
Laboratory and clinical studies have shown that removal of the existing restoration will remove significant healthy tooth structure, subsequently resulting in larger dental restorations. The removal of existing restorations may also cause additional stress on the tooth, with possible pulp reaction to thermal, chemical, bacterial, or mechanical stimuli, depending on the size and depth of the existing restoration.
Therefore, the decision to replace existing restorations should be taken cautiously, as it may significantly affect the remaining tooth structure and, consequently, impact the longevity of future restorations and the lifespan of the tooth. Studies have demonstrated that replacing an existing restoration will not necessarily guarantee that the new restoration will surpass the clinical performance of other alternative treatments such as repair, sealing or monitoring.
Long-term clinical studies have also shown that when alternative treatments fail, the failure usually takes place within 24 months. When the clinician is evaluating an existing restoration with one or more localized clinical features that deviate from ideal and the restoration is considered defective, the clinician should assess whether the tooth in question will truly benefit from a new restoration. When the practitioner is faced with a borderline situation, the patient’s past dental history and current caries risk status, and the best treatment for the tooth in question should be considered. If the practitioner is unsure whether the defective area can be removed by polishing or by sealing the affected area, another conservative and predictable approach would be to repair the restoration by removing the deteriorated area and re-restoring this area only.
Generally, replacement should only take place if the practitioner cannot properly manage the defective areas without removing the entire restoration, or if there are pulpal symptoms.
How successful are repaired restorations?
Minimal Intervention Dentistry aimed to limit unnecessary removal of healthy tooth structure, and repair of defective restorations is one of its strategies. Although the repair of resin composite restorations has been investigated extensively and found successful, dental practitioners do not routinely consider this treatment option in the management of defective restorations.
Although considered a long lasting treatment by the schools teaching this practice, a practice-based research study showed that only practitioners who practiced in non-fee service settings, practitioners with fewer years since graduation from dental school, and practitioners who assessed caries risk, chose preventive treatment options more often than replacement when assessing defective restorations The preference for replacement of restorations may be the result of a complex interplay between the lack of clear standards for replacing restorations and lack of an existing reimbursement for these treatments. That same study reported that general practitioners would most likely intervene surgically in a defective resin composite restoration but not in a defective amalgam restoration.
So far, prospective studies have shown that repaired restorations in permanent teeth have the same or increased longevity as restorations that were replaced completely. Repair treatment remained stable over a 7-year observation period. Additionally, the reason that repaired restorations may even outlast those that were replaced probably relates to the fact that most of the restoration’s original form is kept intact, limiting the introduction of new elements that can affect the success of the restoration. When other restoration stress factors are considered, such as stress on the tooth, post-operative sensitivity, and re-exposure of the dentinal tubules with possible pulpal reactions to thermal or mechanical stimulus, damage to the adjacent tooth and the possibility of more complex restorations, it makes perfect sense to pursue the repair of defective restorations as a predictable and conservative approach to preserving tooth structure. A recent overview regarding restoration margins concludes that margin defects, without visible evidence of soft dentin on the wall or base of the defect, should be monitored, repaired or resealed, in lieu of total restoration replacement.
Besides being a successful treatment, restoration repair is also practical. Defective restorations can be repaired more quickly and with lower operational costs than replacement. Therefore, repaired restorations could present a reduction in patient and/or the third party payers’ expenses which would potentially increase the number of individuals who could afford dental care. The cost of care and oral health are severely impacted by the replacement of existing restorations. Examining outcomes of alternative treatment to the replacement of restorations and establishing consistent criteria that will affect general practitioners’ treatment decisions is a critical issue that may profoundly change the over-treatment of existing restorations.
In summary, dental practitioners should consider repairing truly defective restorations, an appropriate minimal invasive operative intervention worth pursuing.