Chapter 9.4: Operative Treatment and Monitoring of Coronal Caries in Daily Practice

After the caries lesion reaches a certain extent of tooth structure loss, a restoration is often needed to repair the defect. Operative interventions in cariology aim to aid biofilm removal and lesion arrest by cavity sealing, avoid pulpal damage, and restore form, function, and esthetics. There are no clear evidence-based parameters to determine the most appropriate treatment option for each clinical situation. Despite of this, direct composite resins have been the preferable restorative treatment. Scientific literature shows that composites and adhesive strategies play a minor role in treatment success. Patient-related risk factors (mainly those associated with lifestyle and health choices), in addition to the dentist's decision-making process, play a significant role in longevity of the restorations, which tend to fail for the same reasons that lead to the need for restoration (dental caries, tooth/restoration fracture, and esthetics). Therefore, monitoring old restorations in clinical service, even if those present clear signs of degradation, is possible and reasonable within the concept of minimal intervention in dentistry. Unnecessary reinterventions are harmful and costly to health systems, and the clinician's efforts must be directed to eliminating or reducing the etiological factors that can cause the restoration to fail. Thus, patient risk factors assessment is a crucial point in monitoring restorations. Clinician should - whenever possible - postpone operative reinterventions, monitoring the etiological factors that may compromise the restoration's longevity. Also, when operative reintervention is necessary, refurbishment, polishing, and repair should be prioritized over replacement.

Influence of the Inoculum Source on the Cariogenicity of in vitro Microcosm Biofilms

This study investigated the cariogenic potential of biofilms originating from different types of inoculum (saliva and dental plaque) from caries-active and caries-free individuals. Ten volunteers were selected from each caries condition for the paired collection of saliva and dental plaque. Microcosm biofilms were grown in triplicate from each inoculum on enamel specimens in 24-well plates under cariogenic challenge. After 10 days, the biofilms were collected for analysis of outcome variables: percentage of surface hardness change (%SHC) and microbiological composition of biofilms. Statistical analysis was performed using the t test, the linear multivariate analysis model and Pearson's correlation coefficients (α = 0.05). A comparative analysis between microbiological baseline data showed higher counts of mutans streptococci in plaque samples within caries-active individuals; a comparative analysis of colony-forming unit (CFU) counts between individuals with different caries status showed higher counts of acid-tolerant microorganisms and mutans streptococci in dental plaque and of acid-tolerant microorganisms in saliva. After 10 days of biofilm growth, the CFU values for total microorganisms, lactobacilli, mutans streptococci and acid-tolerant bacteria, as well as for SHC, were not statistically significant, considering the type of inoculum and caries condition (p > 0.05). A positive correlation was found for %SHC and CFU counts of acid-tolerant bacteria (r = 0.406) and lactobacilli (r = 0.379). Under the limits of this study, the cariogenic potential of biofilms, formed under identical conditions in vitro, is similar, regardless of baseline differences between the source and type of inoculum.

Secondary Caries Development in in situ Gaps next to Composite and Amalgam

This in situ study investigated the secondary caries development in dentin in gaps next to composite and amalgam. For 21 days, 14 volunteers wore a modified occlusal splint containing human dentin samples with an average gap of 215 µm (SD=55 µm) restored with three different materials: Filtek Supreme composite, Clearfil AP-X composite and Tytin amalgam. Eight times a day, the splint with samples was dipped in a 20% sucrose solution for 10 min. Before and after caries development, specimens were imaged with transversal wavelength independent microradiography, and lesion depth (LD) and mineral loss (ML) were calculated. The LD and ML of the three restoration materials were compared within patients using paired t tests (α=5%). In total 38 composite samples (Filtek n=19 and AP-X n=19) and 19 amalgam samples could be used for data analysis. AP-X composite presented the highest mean values of LD and ML of the three restorative materials. Amalgam showed statistically significantly less ML (Δ=452 µm×vol%) than the combined composite materials (p=0.036). When comparing amalgam to the separate composite materials, only AP-X composite showed higher ML (Δ=515 µm×vol%) than amalgam (p=0.034). Analysis of LD showed the same trends, but these were not statistically significant. In conclusion, amalgam showed reduced secondary caries progression in dentin in gaps compared to composite materials tested in this in situ model.

The influence of different restorative materials on secondary caries development in situ

OBJECTIVES

The effect of direct restorative materials on caries lesion formation was investigated with an 8-week in situ study with split-mouth design, testing the hypothesis that no difference in mineral loss next to a restoration would be found between different composite-based-materials and amalgam.

METHODS

Six groups (n=18) of restored dentine samples were prepared using amalgam, a microhybrid, a nanohybrid and a silorane composite. The composites were adhesively bonded with systems with or without an antibacterial monomer (Clearfil-SE-Protect, Clearfil-SE-bond, respectively), except for the silorane group (Silorane-System-Adhesive). Non-restored dentine samples were used as control (primary caries). Samples were inserted into slots, in lower prosthesis especially made for the experiment. Subjects were instructed to dip the lower prosthesis in a sucrose solution 4 times per day. At baseline and 8 weeks, samples were radiographed extra-orally and the integrated mineral loss was calculated. Data were statistically analyzed using multiple linear regression with a multilevel model (p=0.05).

RESULTS

Nine subjects were selected, and only outer lesions were observed. The hypothesis was partially rejected, as the microhybrid composite bonded with the antibacterial system and the nanohybrid composite presented statistically significant lower mineral loss compared to amalgam. Also, no significant differences were seen for these groups compared to control.

CONCLUSION

Within the limits of this study, the restorative material may influence outer lesion progression. Amalgam was not found to be related to lower secondary caries progression in dentine compared to composite-based materials after 8 weeks in situ.

CLINICAL SIGNIFICANCE

Although patient factors play a major role in caries progression, the restorative material may affect outer secondary lesion progression.