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Current status of conservative treatment of deep carious lesions Juliana Mattos Giulia Marins Soares Apoena de Aguiar Ribeiro Dental Update 2024 41:5, 707-709.
Authors
JulianaMattos
Student at School of Dentistry, Fluminense Federal University
Traditionally, deep carious lesions are treated by removal of all carious tissue, which may lead to pulp exposure. To minimize this risk, conservative carious tissue removal techniques have been proposed, including partial removal and stepwise excavation. However, there is no consensus in the literature about which is the better technique. Thus, the aim of this article is to describe and discuss the main techniques for carious tissue removal, according to scientific evidence. It was observed that both stepwise excavation and partial carious tissue removal presented lower pulp exposure rates and higher success rates.
Clinical Relevance: Clinicians must be aware that conservative carious tissue removal techniques, such as stepwise excavation and partial carious tissue removal, present lower pulp exposure rates and higher success rates than traditional methods.
Article
Dental caries lesions are a localized pathology resulting from biofilm accumulation and its metabolism on tooth surfaces.1 Lesions affect a large proportion of the population, leading to severe problems in the stomatognathic system. In the case of deep caries lesions, complete removal of the carious tissue close to the pulp frequently leads to pulp exposure.2,3 In these cases, many dentists resort to more invasive procedures, such as direct pulp capping, pulpotomy or pulpectomy. However, it is known that vital pulp tissue maintains a capacity of defence against the advance of carious lesions. It is the best barrier that acts against bacterial invasion,4 and this emphasizes the importance of preserving a layer of dentine to protect the pulp.5
In order to prevent or minimize the potential complications of complete excavation of carious dentine close to the pulp, many authors have studied and proposed alternative approaches to the treatment of deep carious lesions. Among these alternatives, partial carious tissue removal3,4,6,7,8 and stepwise excavation2,5,9,10,11,12 are the most common. However, today there is still no scientific evidence about which approach should be preferred in dental practice; that is to say, it has still not been proved whether it is necessary or not to re-open and re-excavate teeth submitted to partial carious tissue removal.6 Thus, the aim of this article is to present the treatment techniques for deep carious lesions and discuss them in the light of evidence-based studies.
Review and discussion
The discussion about the quantity of carious tissue to remove in order to halt the carious process is not new. In 1859, Tomes wrote that ‘it is better to retain a layer of carious dentin to protect the pulp than to run the risk of sacrificing the tooth’. However, in 1908, Black disagreed, saying that ‘it is better to expose the pulp of a tooth than leave it covered with softened dentin’.13
Thus, complete carious tissue removal has been considered an essential step in the treatment of caries lesions, assuming that the success of restorative treatment depends on complete elimination of the bacteria.14 Direct complete excavation consists of complete removal of the carious tissue in only one visit. To perform this, dentine excavators and low speed burs are used until hardened dentine is reached.3,6 In this procedure, the tooth would be ready to be restored when no soft dentine is detected after probing the bottom of the cavity with moderate pressure.3
However, complete carious tissue removal in a single session frequently leads to pulp exposure,2,9 and, therefore, conservative approaches have been proposed for the management of deep lesions, considering that the curative potential of the dentinopulp complex is much greater than was supposed in the past. Therefore, acute caries treatment has been directed towards deterring its progression and promoting cure by dentinal sclerosis and repair.15
One of the conservative approaches for the treatment of deep caries lesions has been stepwise excavation. This technique is indicated for teeth that present high risk of pulp exposure if submitted to direct complete excavation. To be suitable for stepwise excavation, the tooth should not present spontaneous or provoked pain; although moderate pain on thermal stimulation is accepted. In addition, the tooth should respond positively to pulp sensitivity tests and previous radiographic evaluation should not show signs of periapical pathology.10
Stepwise excavation involves the removal of carious tissue in stages.16 Therefore, in the first session, the peripheral demineralized dentine is completely removed as well as only the superficial parts of the necrotic and demineralized central dentine, thus leaving the softened and wet tissue on the pulp wall.12 After this, the base of the cavity may be lined with calcium hydroxide-based medication (although this is not essential) and the tooth is sealed with temporary restorative material.16,17 After a treatment interval of 22,5 to 12 months,12 the temporary restoration and remaining carious tissue are removed,3,5,12 so that the final cavity is as hard as one where there was an indirect complete excavation technique used.2 The base of the cavity is once again lined with calcium hydroxide (although this is not essential) and the tooth is restored with permanent material.3,11Figure 1 shows a clinical case of stepwise excavation.
The purpose of the first stepwise excavation session is to halt the progression of the lesion, by changing the cariogenic environment, rather than removing the carious dentine close to the pulp.18 After the treatment interval, it is easier to distinguish between hardened and softened dentine. This facilitates final excavation and reduces the risks of pulp exposure.2
Figure 1. Clinical case of a second primary molar, treated with stepwise excavation technique. First session: (a) Initial aspect of the dentine lesion. (b) The peripheral demineralized dentine was completely removed as well as only the superficial parts of the necrotic and demineralized central dentine, thus leaving the softened and wet tissue on the pulp wall. (c) The tooth was sealed with temporary restorative material (glass ionomer cement). Second session: (d) After a treatment interval of 4 months, the clinical aspect of the demineralized dentine, immediately after temporary filling removal. (e) The remaining carious tissue was removed. (f) The tooth was restored with permanent material (composite).
One of the advantages of stepwise excavation is the possibility of clinically monitoring the alterations that occur in the dentine during the treatment interval. Various studies have demonstrated that, after the treatment interval, the dentine becomes dried, hardened and darker, indicating that the carious lesion has been arrested.3,11,12,16 Moreover, the results of microbiologic analysis between the stages of stepwise excavation have demonstrated that the total colony forming unit (CFU) counts of S. mutans and Lactobacillus were gradually reduced during the treatment.3,11,12 It has also been demonstrated that the distribution of the species found in the dentine after the treatment interval did not characterize the typical microbiota of deep lesions, which confirms the clinical findings that lesions had been arrested.11
An even more controversial technique for the treatment of deep caries lesions is the conservative or ultraconservative removal of carious tissue, sometimes called partial carious tissue removal. This technique is based on the concept that the carious process is guided by caries activity in the biofilm, therefore, this process could be halted simply by sealing the cavity.13
The partial removal protocol recommends that, after total elimination of the superficial parts of necrotic dentine, excavation continues until a partial removal of demineralized central dentine (similar to the first stage of stepwise excavation) and then leaving a thick layer of softened dentine on the pulp wall.3,6,16,17 After this, the carious tissue must be completely removed only from the cavity walls, in order to obtain adequate sealing of the restoration. After partial excavation, the base of the cavity may be lined with calcium hydroxide (although this is not essential) and the cavity is filled with a permanent restorative material, with no re-entry in the cavity.7,16,17
Some studies have made longitudinal evaluations of teeth with deep caries lesions treated with partial carious tissue removal. Maltz et al,7 after 36–45 months of follow-up, observed a success rate (that is to say, maintenance of pulp vitality and absence of symptoms) of 88% of the permanent teeth treated. Similarly, in the study of Gruythuysen et al,4 a success rate was observed (that is to say, absence of symptoms and clinical and radiographic signs of pathology) in 96% of primary and 93% of permanent molars, after 3 years.
Considering that there is no consensus about the best treatment technique for deep carious lesions, it is important to carry out clinical trials. Table 1 presents the studies that compared direct complete excavation and stepwise excavation.
Reference
Dentition
Percentage of pulp exposure in direct complete excavation
Percentage of pulp exposure in stepwise excavation
No statistically significant difference in the total CFU counts.
Those who defend the partial removal technique allege that re-opening the cavity during stepwise excavation may lead to pulp exposure and result in future damage to the pulp. This hypothesis may be verified in the study of Orhan et al,6 in which it was demonstrated that pulp exposures in the group treated with stepwise excavation always occurred during cavity re-opening. Another point questioned in stepwise excavation is the use of temporary restoration between sessions, which may become lost or are forgotten by patients, which would increase the chances of failure of the technique.6
Stepwise excavation has advantages. Final excavation helps the dentist to control the reaction of the tooth, and allows the removal of dentine with slow progression of demineralization, but nevertheless infected, before performing the permanent restoration.6,10,17,18,20
Conclusion
Based on the studies cited in this review, the authors suggest that the conservative techniques for the treatment of deep carious lesions, namely stepwise excavation and partial removal, are preferable to direct complete excavation, since they present less risk of pulp exposure and higher success rates. There is no consensus about which technique is better – partial removal or stepwise excavation.
