Selective Removal to Soft Dentine vs Selective Removal to Firm Dentine for Deep Posterior Caries Lesions

Removal of infected dentin contaminated with bacteria and remaining affected dentin detected as firm is the conventional strategy for the management of cavitated caries lesions. Recently, this strategy is termed as selective removal to firm dentin (SRFD) and seems to increase the potential risk of pulp exposure or loss of pulp vitality for deep caries lesions radiographically extending ¾ of dentin tissue. Alternatively, selective removal to soft dentine (SRSD) that refers to removal of caries tissue at the periphery of the cavity to firm dentin and remaining caries tissue detected as soft or leathery in proximity with the pulp might be a less invasive excavation method for deep caries lesions to maintain pulpal health. However, information on clinical advantages or disadvantages of SRSD and SRFD excavation methods is sparse and mostly rely on studies conducted for primary teeth. Moreover, clinical trials are needed to demonstrate the combined effect of carious removal strategies and calcium silicate-based materials.

The aim of this study is comparison of clinical success rates of SRSD and SRFD techniques in posterior deep caries lesions. The primary outcome of the study is comparison of clinical success of SRSD and SRFD techniques by clinical and radiographic examination after 3 months, 6 months, 1 year and 2 years. The secondary outcome of the study is to investigate whether or not calcium silicate-based materials have an effect on the success rate of the treatment.

In recent years, there has been growing number of studies questioning conventional caries tissue removal, especially for deep caries lesions (1). In the concept of conventional caries tissue removal, 'affected dentin' and 'infected dentine' are widely used terms which have been defined by Massler (2) in 1960s. According to this concept, removal of infected dentin contaminated with bacteria and remaining affected dentin detected as firm suggested for the management of cavitated caries lesions. Recently, this removal technique is termed as selective removal to firm dentin (SRFD) and seems to increase the potential risk of pulp exposure or loss of pulp vitality for deep caries lesions radiographically extending ¾ of dentin tissue (3). In case of pulp exposure, direct pulp capping is the treatment of choice for a tooth with a vital pulp and without any inflammation predictors such as prolonged bleeding. However, according to results of a long term (5-10 years) retrospective study evaluating the treatment outcome of direct pulp capping with calcium hydroxide, 44.5% in the 5-yr group and 79.9% in the 10-yr group had a postoperative root canal treatment or an extraction (4). Similarly, another restrospective study showed that over the first year after direct pulp capping with calcium hydroxide , almost 10% and, after 5 years, nearly 20% of the teeth had an unfavourable treatment outcome (5).According to results of these studies, survival rate of directly capped pulp tissue with calcium hydroxide seems to decrease over time.

Recently, Biodentine (BD; Septodont, St Maur-des-Fosses, France), which is a calcium silicate-based material, has gained popularity for pulp capping treatment. The success rate of Biodentine reported to be 91.7% after 3 years in a recent prospective longitudinal randomized controlled study of vital permanent teeth with deep caries (6). Except from the material of choice for pulp capping, some other strategies such as selective removal to soft dentin (SRSD) has been recently recommended for the management of deep caries lesions with the aim of reducing the risk of pulp exposure.

Accorging to report of International CariesConsensus Collaboration (ICCC) group SRSD is strongly recommended in deep cavitated lesions extending into ¾ of dentin tissue. Soft carious tissue is left over the pulp to avoid pulpal exposure and peripheral enamel and dentine are prepared to hard dentine, to provide hermetic sealing and durability of the restoration.

In the literature, there are very few studies concerned with the clinical success of SRSD, incomplete caries removal (ICR) or partial caries removal (PCR). In a long term (10 years) prospective cinical study, the success rates of PCR technique has been reported as, 90% after 3 years, 82% after 5 years and %63 after 10 years (7). In another clinical study comparing 24-month pulp health outcomes of PCR and total caries removal (TCR) in primary molars, no significant diffrence between the two removal techninues and reduced risk for pulp exposure with PCR technique has been reported (8). In a recently published review, it has been reported that SRSD seems to be the best option for the treatment of deep caries lesions and the remaining caries tissue close to the pulp seems not to interfere the longevity of the restorations (9).Nevertheless, not much scientific evidence on clinical success of SRSD and SRFD excavation methods for deep carious lesions in permanent teeth could be found in the currently available literature. Moreover, clinical trials are needed to demonstrate the combined effect of carious removal strategies and calcium silicate-based materials.

The aim of this study is comparison of clinical success rates of SRSD and SRFD techniques in posterior deep caries lesions of permanent teeth. This study will be carried out as a prospective randomized, double-blinded, clinical trial, with 2 parallel groups. Potential patients attending to Istanbul Medipol University Dental Clinics in Istanbul with deep posterior caries lesions will be invited to the study. The patients meeting the inclusion criteria will be recruited and randomized into SRSD group and SRFD group by block randomization of 2.1 ratio.

After giving their consent to take part in the study, defined clinical procedure for each group will be performed. In SRFD group (Goup B), after caries removal to firm dentin calcium silicate based material (Biodentine) will be applied. If the excavations led to pulp exposure, pulp-capping with calcium silicate based material will be performed and this patients will be randomized to another group (Group PC).The patients in SRSD group will be randomized into two subgroups as Group A and Group C. In group A after caries removal to soft dentin calcium silicate based material (Biodentine) will be applied. In group C after caries removal universal adhesive material will be applied without calcium silicate based material placement. All the restorations will be performed by the same operator using the same universal adhesive and resin composite material. The observers (two independent observer) and the patients will be blinded for the actual intervention performed.

The primary outcome of the study is comparison of clinical success of SRSD and SRFD techniques by clinical and radiographic examination after 3 months, 6 months, 1 year and 2 years. The secondary outcome of the study is to investigate whether or not calcium silicate-based materials have an effect on the success rate of the treatment. Statistical comparisons will be performed between Group A and Group B for the primary outcome and between Group A and Group C for the secondary outcome.

Eligibility Criteria:
Inclusion Criteria:

* Deep primary active caries lesion extending at least 3/4 of dentin
* No irreversible pulpitis symptoms
* Positive response to electrical and cold pulp vitality tests
* Good general health
* No untreated periodontal disease
* Acceptance to be included in study

Exclusion Criteria:

* Irreversible pulpitis symptoms
* Negative response to electrical and cold pulp vitality tests
* Radiographically periradicular pathology
* Pregnancy
* Teeth with non-carious lesions (attrition, erosion, abrasion or abfraction)
* Patients planning bleaching or orthodontic treatment
* Known allergy to study material