Microbial Load After Selective and Complete Caries Removal in Permanent Molars: a Randomized Clinical Trial

3-year randomized clinical trial to evaluate the performance of posterior composite restorations lined with ion-releasing materials

To evaluate the impact of using ion-releasing liners on the 3-year clinical performance of posterior resin composite restorations after selective caries excavation with polymer burs. 20 patients were enrolled in this trial. Each patient had two deep carious lesions, one on each side of the mouth. After selective caries removal using polymer bur (PolyBur P1, Komet, Brasseler GmbH Co. KG, Lemgo, Germany), cavities were lined with bioactive ionic resin composite (Activa Bioactive Base/Liner, Pulpdent, Watertown, MA, USA) or resin-modified glass ionomer liner (Riva Light Cure, SDI, Bayswater, Victoria, Australia). All cavities were then restored with nanofilled resin composite (Filtek Z350XT, 3M Oral Care, St. Paul, MN, USA). All the tested materials were placed according to the manufacturers' instructions. Clinical evaluation was accomplished using World Dental Federation (FDI) criteria at baseline and after 6 months, 1, 2, and 3 years. Data were analyzed using Mann-whitney U and Friedman tests (p < 0.05). The success rates were 100% for all resin composite restorations either lined with ion-releasing resin composite or resin-modified glass ionomer liner. Mann-whitney U test revealed that there were no statistically significant differences between both ion-releasing lining material groups for all criteria during the follow-up periods (p > 0.05). Resin composite restorations showed acceptable clinical performance over 3 years either lined with bioactive ionic or resin-modified glass ionomer liners after selective caries excavation preserving pulp vitality. After the 3-year follow-up period, Activa Bioactive and Riva Light Cure liners were clinically effective and they exhibited with the overlying composite restorations successful clinical performance.Trial registration number: NCT05470959. Date of registration: 22/7/2022. Retrospectively registered.

Er:YAG laser in selective caries removal and dentin treatment with chitosan: a randomized clinical trial in primary molars

This study evaluated the effect of chitosan on dentin treatment after selective removal of caries lesions with Er:YAG laser in reducing Streptococcus mutans, as well as its effect on the performed restorations. The sample consisted of children (aged 7 to 9 years) with active carious lesions and dentin cavitation located on the occlusal surface of deciduous molars. Eighty teeth were randomly distributed into 4 groups according to the caries removal method: Er:YAG laser (250 mJ/4 Hz) or bur and dentin surface treatment: 2.5% chitosan solution or distilled water. The bacterial load of caries-affected dentin was quantified by counting CFU/mg (n = 10). The teeth were restored and evaluated at 7 days, 6 months, and 12 months using modified USPHS criteria (n = 20). Microbiological data was analyzed by Mann-Whitney and clinical analyses were done using Kruskal-Wallis and Dunn test (α = 0.05). The results showed that the Er:YAG laser significantly reduced the amount of Streptococcus mutans (p = 0.0068). After dentin treatment with chitosan, there was a significant reduction in the amount of Streptococcus mutans for both removal methods (p = 0.0424). For the retention and secondary caries criteria, no significant differences were observed along the evaluated time (p > 0.05). The laser-treated group was rated "bravo" for discoloration (p = 0.0089) and marginal adaptation (p = 0.0003) after 6 and 12 months compared to baseline. The Er:YAG laser reduced the amount of Streptococcus mutans and the chitosan showed an additional antibacterial effect. After 1 year, the Er:YAG laser-prepared teeth, regardless of the dentin treatment, showed greater discoloration and marginal adaptation of the restorations.

Cost-effectiveness of selective caries removal versus stepwise excavation for deep caries lesions

A multicenter, randomized controlled clinical trial evaluated the effectiveness of two treatments for deep caries lesions in permanent molars - selective caries removal (SCR) to soft dentin with restoration in a single visit, and stepwise excavation (SW) - regarding pulp vitality for a 5-year follow-up period. The present study aimed to determine the cost-effectiveness of these treatments. Treatments were conducted in two Brazilian cities (Brasília and Porto Alegre). At baseline, 299 permanent molars (233 patients) were treated and 229 teeth (174 patients) were evaluated after 5 years. The discounted cash flow method was adopted. The total cost of each treatment was calculated, and the failure cost (endodontic treatment + restoration) was added to the final cost, according to the 5-year failure rates of each therapy (20% for SCR and 44% for SW). A public health service unit composed of three dentists in 4-hour work shifts was used to calculate the monetary value of the treatments, assuming a total of 528 treatments/month. Considering the 229 teeth evaluated after 5 years (115 SCR and 114 SW), SCR provided savings of 43% (amalgam) and 41% (resin composite) per treatment, compared to SW. The SCR technique provides benefits for public finances (direct economy) and for public health services (increase in the number of treatments performed). Considering that maximizing profit and reducing costs are powerful motivating factors for adopting a certain treatment, this study provides data to better support the decision-making process, regarding the management of deep caries lesions in permanent molars.

Microshear Bond Strength of Bioactive Materials to Dentin and Resin Composite

OBJECTIVES

 The aim of this study was to comparatively evaluate microshear bond strength (μSBS) of bioactive ionic resin composite and resin-modified glass ionomer liner (RMGI) to dentin and resin composite.

MATERIALS AND METHODS

 The enamel of 11 posterior molar teeth was removed to expose dentin and then placed in acrylic blocks. Each specimen received three microcylindrical Tygon tubes filled with bioactive ionic resin composite (Activa Bioactive base/liner (PULPDENT: , MA, USA)), RMGI (Riva light cure SDI LTD, Bayswater, Australia), and resin composite (Filtek Z350xt, MN, USA). Composite discs (n = 11) were fabricated from nanofilled resin composite (Filtek Z350xt) and then fixed in acrylic blocks. Each specimen received two microcylindrical Tygon tubes filled with Activa Bioactive base/liner and Riva RMGI. All specimens were mounted individually to universal testing machine for μSBS test. Failure modes were analyzed using stereomicroscope and scanning electron microscope.

RESULTS

 Filtek Z350xt nanofilled resin composite showed the highest μSBS values. No statistical significant difference was found between Activa Bioactive and Riva RMGI (p > 0.05).

CONCLUSION

 Bioactive ionic resin composite liner exhibited similar bond strength as RMGI to dentin and resin composite.

Current Strategies to Control Recurrent and Residual Caries with Resin Composite Restorations: Operator- and Material-Related Factors

This review addresses the rationale of recurrent and/or residual caries associated with resin composite restorations alongside current strategies and evidence-based recommendations to arrest residual caries and restrain recurrent caries. The PubMed and MEDLINE databases were searched for composite-associated recurrent/residual caries focusing on predisposing factors related to materials and operator’s skills; patient-related factors were out of scope. Recurrent caries and fractures are the main reasons for the failure of resin composites. Recurrent and residual caries are evaluated differently with no exact distinguishment, especially for wall lesions. Recurrent caries correlates to patient factors, the operator’s skills of cavity preparation, and material selection and insertion. Material-related factors are significant. Strong evidence validates the minimally invasive management of deep caries, with concerns regarding residual infected dentin. Promising technologies promote resin composites with antibacterial and remineralizing potentials. Insertion techniques influence adaptation, marginal seal, and proximal contact tightness. A reliable diagnostic method for recurrent or residual caries is urgently required. Ongoing endeavors cannot eliminate recurrent caries or precisely validate residual caries. The operator’s responsibility to precisely diagnose original caries and remaining tooth structure, consider oral environmental conditions, accurately prepare cavities, and select and apply restorative materials are integral aspects. Recurrent caries around composites requires a triad of attention where the operator’s skills are cornerstones.

Alkyl trimethyl ammonium bromide for the formulation of antibacterial orthodontic resins

OBJECTIVES

This study aimed at formulating antibacterial orthodontic resins containing alkyl trimethyl ammonium bromide (ATAB) and evaluating their physicochemical and biological properties.

MATERIALS AND METHODS

The chemical composition and microstructure of ATAB was characterized through FTIR and SEM, respectively. Experimental orthodontic BisGMA/TEGDMA-based resins were formulated, and the ATAB filler was incorporated at 1wt%, 5wt%, and 10wt%, along with colloidal silica (5wt%). The degree of conversion, softening in solvent, and flexural strength of the experimental resins were analyzed. Biological properties were also assessed through cytotoxicity and antibacterial analyses.

RESULTS

The incorporation of ATAB, due to the presence of ⎯N⁺(CH₃)₃ alkyl groups, had no adverse effect on the degree of conversion of the resins (p > 0.05). The %ΔKHN values at 5wt% and 10wt% were comparable to those of the control group, while the flexural strength was reduced at all concentrations of ATAB. The viability of the gingival fibroblast was reduced with the addition of ATAB (p < 0.05). The viability of biofilm and planktonic bacteria was reduced when ATAB was incorporated at 5wt% and 10wt%.

CONCLUSIONS

The addition of ATAB at 5wt% resulted suitable for the formulation of orthodontic resins with the ability to control the biofilm formation and planktonic activity of S.mutans, without jeopardizing some specific physicochemical properties.

CLINICAL RELEVANCE

White spot lesions in orthodontic patients may be controlled by preventive treatments. Non-patient-dependent strategies, such as the use of orthodontic resins containing ATAB, may avoid accumulation of bacteria, especially in those areas surrounding orthodontic appliances.

The effect of selective carious tissue removal and cavity treatments on the residual intratubular bacteria in coronal dentine

Background/purpose

The use of cavity treatments may help in the reduction of bacteria remaining in dentinal tubules after selective carious tissue removal. This study aimed to investigate the effect of selective carious tissue removal and treatment with either 35% phosphoric acid +0.12% chlorhexidine or dentine conditioner on the residual intratubular bacteria in coronal dentine of deep carious lesions.

Materials and methods

Thirty carious human molars were randomly divided into three groups; group 1: untreated carious teeth (positive control), group 2: carious teeth treated with 35% phosphoric acid and chlorhexidine disinfectant after selective carious tissue removal and group 3: carious teeth treated with dentine conditioner after selective carious tissue removal. Another six non-carious teeth was used as negative control. The presence of bacteria and depth of bacteria remaining in dentinal tubules were determined by scanning electron microscopy (SEM). Chi square test and one-way, repeated-measures analysis of variance were used for statistical analysis.

Results

Using SEM, coronal dentine of group 1, 2 and 3 revealed cocci, rod and filamentous bacteria within dentinal tubules. Positive rates of bacteria detection in coronal dentine of group 1 were significant higher than those of group 2 and 3 (P < 0.05). The distance of bacteria remaining in the dentinal tubules in group 1, 2 and 3 were 1149.14 ± 384.44, 707.98 ± 357.19 and 869.25 ± 470.75 μm, respectively.

Conclusion

Both treatment groups had similar ability to reduce the number of intratubular bacteria in coronal dentine of carious teeth, but not complete elimination.

Characterization of Lactobacilli isolated from carious dentin after selective caries removal and cavity sealing

OBJECTIVE

To characterize lactobacilli isolated from residual carious dentin after selective caries removal (SCR), by observing the changes detected in their prevalence, diversity, and cariogenic potential after starvation stress caused by cavity sealing (CS).

DESIGN

Lactobacilli were cultured from carious dentin lesions (n = 16 patients) treated in a clinical trial, three months before and after CS. Presumptive lactobacilli were selected, isolated, and analyzed by Gram staining. Housekeeping gene sequences were used to identify the species (groEL, rpoA, pheS, and 16S rRNA).

RESULTS

N = 86 Lactobacillus spp. (n = 41 before and n = 45 after sealing) were genotyped by AP-PCR and analyzed for their cariogenic potential (acid production and acid tolerance). The proportion of lactobacilli to the total anaerobic counts was high, and a significant decrease was observed after sealing (median before sealing = 78.9; 25th-75th = 60.25-97.35; median after sealing = 0.00; 25th-75th = 0.00-77.08; p = 0.001). L. paracasei was the most prevalent species of lactobacilli in carious dentin (p = 0.02). L. rhamnosus prevalence increased to a proportion similar to L. paracasei after CS (p = 0.001). A total of 28 and 14 different genotypes were found before and after CS, respectively. There was no difference between the L. paracasei and the L. rhamnosus isolated from carious dentin, neither regarding acid production nor acid tolerance.

CONCLUSIONS

Although there was a significant reduction in lactobacilli in the residual carious dentin after SCR, some strains were capable of surviving after three months of CS. However, the sealed available nutrients are low and not sufficient for caries progression. Also, we believe that a longer follow up period may eliminate all the residual lactobacilli. L. paracasei prevailed in carious dentin in a proportion similar to L. rhamnosus in the sealed dentin. Characterization of lactobacilli after SCR and sealing may help the understanding the importance of genotyping of lactobacilli in carious microbiota.

Influence of selective caries excavation on marginal penetration of class II composite restorations in vitro

Selective caries excavation may support pulp preservation. This in vitro study investigated the influence of selective removal of demineralized dentin on marginal integrity of composite restorations as determined by dye penetration. Dentinal caries-like lesions were produced in the approximal surfaces of 40 extracted human molars (ethylenediaminetetraacetate, 0.5 M, 96 h). The following test procedures were established: complete excavation, selective excavation, and caries-free control. Two class II cavities with enamel at the cervical margins were prepared per tooth and demineralization volume was determined by micro-computed tomography for the purpose of a stratified distribution to receive complete excavation or selective excavation. After complete or selective excavation (30 cavities each), adhesive composite restorations were placed. Cavities without demineralized dentin (20 cavities) served as control. The marginal integrity of restorations was evaluated by dye penetration with and without thermocycling or mechanical loading. Results were analyzed by non-parametrical statistical tests (Mann-Whitney U Test) with an α = 0.05 level of significance. Dye penetration did not differ significantly among completely excavated, selectively excavated, or undemineralized teeth, but was increased by thermocycling and mechanical loading in all experimental groups. Selective caries removal did not increase marginal penetration in class II restorations. The presence of remaining demineralized dentin surrounded by sound dentin did not impair marginal integrity of restorations with margins placed in sound enamel.

Influence of black tea on Streptococcus mutans and Lactobacillus levels in saliva in a Saudi cohort

Objectives

Dental caries are associated with high counts of Streptococcus mutans (SM) and Lactobacillus (LB) and low saliva buffering capacity (BC). This study aimed to evaluate the antimicrobial activity of black tea on salivary cariogenic microflora, SM and LB species in an adult population. Antimicrobial activity was measured from the number of colony forming units (CFUs) of SM and LB, and BC of saliva.

Methods

In this prospective experimental study, unstimulated saliva samples were acquired from the participants before, immediately after, and 1 h after drinking tea by collecting saliva in sterilised containers. Samples were taken to the laboratory for incubation and subsequent counting. SM and LB counts and BC of saliva were calculated using the caries risk test (CRT).

Results

A total of 21 participants, 13 males and 8 females, with a mean age of 32.6 ± 8.02, were recruited in this study. Black tea had no significant effect on reducing the cariogenic bacterial counts (p > 0.05).

Conclusion

Based on this study, it can be deduced that black tea exhibits an insignificant antimicrobial effect against Streptococcus mutans and Lactobacillus bacteria.