Removing Carious Tissue: Why and How?

Reduction of microorganisms in carious dentin by photodynamic therapy mediated by potassium iodide added to methylene blue and red laser

OBJECTIVE

To evaluate the effect of the association of potassium iodide to antimicrobial photodynamic therapy on human carious dentin produced with a microcosm biofilm model.

METHODS

A microcosm biofilm model was used to generate a caries lesion on human dentin. Pooled human saliva diluted with glycerol was used as an inoculum on specimens immersed on McBain artificial saliva enriched with 1 % sucrose (24 h at 37 °C in 5 % CO2). After refreshing culture media for 7 days, the dentin specimens were divided in 5 groups (3 specimens per group, in triplicate; n = 9): C (NaCl 0.9 %), CX (2 % chlorhexidine), PKI (0.01 % methylene blue photosensitizer+50 mM KI), L (laser at 15 J, 180 s, 22.7 J/cm2), and PKIL (methylene blue + KI + Laser). After the treatments, dentin was collected, and a 10-fold serial dilution was performed. The number of total microorganisms, total lactobacilli, total streptococci, and Streptococcus mutans was analyzed by microbial counts (CFU/mL). After normality and homoscedasticity analysis, the Welch's ANOVA and Dunnett's tests were used for CFU. All tests used a 5 % significance level.

RESULTS

CX and PKIL groups showed significant bacterial decontamination of dentin, compared to group C (p < 0.05) reaching reductions up to 3.8 log10 for CX for all microorganisms' groups and PKIL showed 0.93, 1.30, 1.45, and 1.22 log10 for total microorganisms, total lactobacilli, total streptococci, and S. mutans, respectively.

CONCLUSION

aPDT mediated by the association of KI and methylene blue with red laser reduced the viability of microorganisms from carious dentin and could be a promising option for cavity decontamination.

Selective Removal to Soft Dentine versus Full Pulpotomy for Management of Proximal Deep Carious Lesions: A Randomized Controlled Non-Inferiority Trial

The management of the deep carious lesion with reversible pulpitis is a dilemma for the dentist. The current study compared selective removal to soft dentine (SRSD) and full pulpotomy (FP) for treating proximal deep carious lesions in teeth with reversible pulpitis. Visual-tactile examination and bitewing radiographs were used to determine the depth of carious lesion, and American Association of Endodontists recommendations were used to formulate pulp diagnosis. Sixty mandibular molar teeth from healthy patients between the ages of 16-35 years and a diagnosis of proximal deep carious lesion with reversible pulpitis were included. Teeth were randomly allocated to two study groups. SRSD group (n = 30): soft dentine was preserved over the pulpal aspect. A hard-setting calcium hydroxide cement liner and resin-modified glass ionomer cement base were applied over the remaining soft carious dentine. FP group (n = 30): complete caries removal followed by mineral trioxide aggregate FP was performed. The teeth in both groups were restored with composite resin restoration. The established criteria for outcome assessment of SRSD and pulpotomy were used. Accordingly, only asymptomatic teeth with no radiological evidence of periapical rarefaction were considered successful at the 12-month follow-up. Two-sample t test, Pearson χ2 test/Fisher's exact test, and percentage agreement were used for statistical evaluation. According to the per-protocol analysis, the success rate of both SRSD and FP treatment was 95.45% and 95.65%, respectively, and the actual difference between the two treatments was 1% (95% CI: [-10, 9]). The data suggests that both treatments (SRSD and FP) appear to have a good success rate (>95%) when used to manage permanent mandibular molar teeth with proximal deep carious lesion and reversible pulpitis. As SRSD is a noninvasive procedure, it should be favored over FP in these instances.

The revolutionary evolution in carious lesion management

Contemporary paradigms of dental caries management focus on the biological approaches to treating the disease and its principal symptom, the carious lesion. This narrative review traces the evolution of carious lesion management from the operative and invasive approaches of G. V. Black's era to the current period of minimally invasive biological approaches. The paper explains the rationale for adopting biological approaches to dental caries management and lists the five core principles of this management approach. The paper also details the aims, features, and the most recent evidence base for the different biological carious lesion management approaches. Based on current practice guidelines, collated clinical pathways for lesion management are also presented in the paper to aid clinicians in their decision-making. It is hoped that the biological rationale and evidence summarized in this paper will bolster the shift to modern biological carious lesion management approaches among dental practitioners.

The Understanding of Vital Pulp Therapy in Permanent Teeth: A New Perspective

The indications of vital pulp therapy (VPT) are expanding, which cases are suitable for VPT, and how to improve the success rate of VPT is a problem that often bothers us. The main purpose of VPT is to eliminate pulpitis by promoting the formation of reparative dentin or calcium bridge, so that it can continue to perform various physiological functions, and finally achieve the purpose of preserving pulp vitality and long-term preservation of affected teeth. Pulp capping and pulpotomy are the most common methods for VPT. The research field of VPT has attracted the attention of many scholars, who have studied it from many aspects (such as indications, material selection, operation requirements, and long-term prognosis). This article reviews the recent advances in the techniques of VPT in permanent teeth.

Should new operating procedures arising from COVID-19 make us re-think our management of deep caries?

COVID-19 has impacted heavily on the delivery of dental services within the UK, particularly in regards to aerosol generating procedures (AGPs). However, it has created an opportunity to reflect on how operative dental procedures, such as the management of dental caries, are undertaken. In light of recent evidence in favour of speed increasing contra-angle handpieces in combination with an electric micromotor to eliminate the generation of aerosols at certain speeds while still allowing the cutting of hard tooth tissue, albeit at a slower rate than the traditional air-turbine, this article explores the evidence for partial caries removal using the electric micromotor system. Aspects of maintaing the health of the pulpal tissue using this system and adopting a logical approach to placing adhesive direct resin composites to faciliate an optimum outcome for the patient are also explored.

M. Is Non-Restorative Cavity Treatment a Practical Choice in Primary Teeth?

For years, “extension for prevention” was considered as the standard protocol for the restoration of caries. With advances in the field of cariology regarding the biofilm and improvement in materials, this perspective is being challenged. This is being challenged by more biological and less-invasive approaches, where the emphasis is on biofilm alteration to arrest carious lesions. This minimally invasive intervention is based on the concept that biofilm overlying the carious lesion is a driving force for the carious process and not the bacteria present in the infected dentin. Hence, daily removal or disruption of this biofilm will slow down the carious process or bring it to halt.

One such approach is non-restorative cavity treatment, where no caries is removed but lesions are made self-cleansable that allows it to be brushed by the parent or the child. This wholesome approach targets the disease at a causal level.

This review of literature describes the various advantages and limitations of this technique and the practicability of its use in pediatric patients during the pandemic COVID-19.

In Vitro Analysis of Organic Ester Functional Groups in Carious Dentine

Background: With the implementation of minimally invasive selective caries removal protocols to treat cavitated, deep carious dentine lesions, there is a need to investigate specific biochemical moiety distributions to help characterise and distinguish between infected (contaminated) and affected (demineralised) zones within the dentine lesion. The present in vitro investigation aimed to compare the distribution of ester functional groups (1740 cm−1) within carious dentine tissue (infected and affected dentine). The null hypothesis stipulated that there are no differences in ester function intensity/distribution within carious dentine lesions. Materials and Methods: From a total of five extracted human molar teeth with carious dentine lesions, 246 points from 10 sections of carious dentine were examined using high-resolution Raman spectroscopy and characterised into infected, affected and sound dentine. The peak intensity of the characteristic vibration mode of the ester function was calculated from sample scans. Results: Analyses indicated a statistically significant difference in the spectroscopic vibration bands of esters between the infected and affected dentine zones. Conclusion: The ester functional group is higher in intensity in the caries-infected dentine zone compared to the affected tissue. This finding could be used to develop an objective indicator for the selective operative management of carious dentine.

Loss of dental tissue after restoration or sealing of occlusal carious lesions: 3-4-year results of randomized clinical trials

Context

Although preservation of the tooth structure is quoted as the main advantage of sealing of carious lesions, there are no long-term studies comparing the maintenance of dental tissue after restoration or after caries sealing.

Aim

To measure the radiographically visible loss of dental tissue after conventional restoration and sealing of carious lesions.

Subjects and Methods

This study was a secondary analysis of two randomized controlled clinical trials, one conducted in Brazil and another in Belgium, which evaluated two different therapies for the treatment of occlusal carious lesions in permanent teeth: sealant (SE) without previous carious tissue removal or restoration (RE) with total removal of carious dentin. The greater depth and width of sealed carious lesions and restorations were compared.

Statistical Analysis

The independent t-test was used to compare therapies at different time points, while the paired t-test was used to compare the same therapy over time.

Results

Carious lesions in the RE and SE groups showed similar measurements at baseline (P > 0.05). Over time, significantly greater loss of tooth structure was observed in the RE group than in the SE group. No increase in lesion depth or width was observed in the SE group, suggesting no progression of sealed lesions.

Conclusion

Sealing of carious lesions resulted in greater preservation of dental tissue.

Selective carious tissue removal and glass ionomer liner reduction of pulp stress in bulk fill resin composite restorations

To evaluate the effect of selective or nonselective carious tissue removal and the use of a resin-modified glass ionomer (RMGIC) liner under bulk fill resin composite restoration on the stress at the pulp chamber, the elastic moduli of hard, firm, soft and intact dentin were calculated using nanoindentation. Post-gel shrinkage of the bulk fill resin composite and RMGIC were determined using the strain-gauge method. Six finite element models were created by using digital radiography with the combination of two study factors: a) carious tissue removal: selective removal or nonselective removal of carious tissue, and b) use of RMGIC liner: with or without 1.0 mm of RMGIC liner. The modified von Mises stresses (mvm) (MPa) were extracted on the nodes of the internal wall of the pulp ceiling chamber at 100 N occlusal loading. Data were analyzed descriptively and recorded quantitively. Both study factors influenced the stress distribution. The mvm stress during the restorative procedure was higher for nonselective carious tissue removal without RMGIC (25.9 MPa) and lower for selective carious tissue removal associated with RMGIC (13.5 MPa). The dentin elastic modulus increased from soft carious (3.6 ± 0.3 MPa) to firm carious (5.2 ± 1.0 MPa) to hard carious (10.9 ± 1.2 MPa) to intact dentin (22.7 ± 3.0 MPa). Molars with carious lesions showed high mvm stress at the pulp ceiling (89.6 MPa) and at fragilized coronal structure remaining. Selective carious tissue removal followed by restoration using a Vitrebond liner and Tetric N-Ceram Bulk fill reduced the stress at the pulp chamber ceiling.

Teaching Minimally Invasive Interventions in Paediatric Dentistry: A Cross-Sectional Survey of Dental Schools in Iran

BACKGROUND

Dental caries is a significant public health problem in Iran. Teaching  minimally invasive interventions in paediatric dentistry may facilitate the provision of treatment for untreated dental caries in children. We evaluated the teaching of such interventions in both undergraduate dental curriculum and Paediatric Dentistry Specialty Training Programme (PDSTP) in Iran.

METHODS

This was a cross-sectional questionnaire-based survey. Participants in this study were the directors of 40 undergraduate programmes and 15 PDSTPs in all Iranian dental schools (response rate = 100%). Descriptive statistics were reported.

RESULTS

The most commonly taught methods were preventive fissure sealant and preventive resin restoration (PRR), which were taught 'both didactically and clinically' in all undergraduate dental programmes. The least commonly taught methods were silver diamine fluoride (SDF), the Hall technique and resin infiltration, which were taught 'both didactically and clinically' in less than 5% of dental schools. The same three methods were the least commonly approaches taught in PDSTP, further, they were less often perceived to be 'essential'.

CONCLUSIONS

There was a notable variation in the teaching of the management of dental caries in Iran's dental education. Some minimally invasive approaches including SDF, the Hall technique and resin infiltration are not being commonly taught in Iranian dental schools despite the evidence base for these techniques.

Pulp liner materials in selective caries removal: study protocol for a randomised controlled trial

INTRODUCTION

The literature shows that selective carious tissue removal (SCTR) decreases the number and diversity of bacteria, stops the caries process and reduces the risk of pulp exposure. However, no consensus exists on which pulp liner would be suitable for teeth undergoing SCTR. So, this study will verify the in vivo response of dentine-pulp complex after SCTR in primary teeth with or without pulp liner material.

METHODS AND ANALYSIS

A randomised clinical trial, double-blinded, parallel-group and allocation concealment will be conducted with the enrolment of 384 patients from 5 to 9 years, with one maxillary/mandibular first/second primary molars with deep occlusal/occlusoproximal cavities. The remaining dentine will be lined with calcium hydroxide cement-group 1; mineral trioxide aggregate-group 2 and without liner-group 3. The primary outcome will be success of the of dentine-pulp complex evaluated clinically and radiographically at 6, 12 and 24 months, while the secondary outcomes will be the measurement of the dentine barrier on periapical radiographs. During all study, two trained and calibrated examiners will evaluate the treated teeth clinically and radiographically. Interexaminer and intraexaminer reliability will be verified by casual and systematic error. The Kolmogorov-Smirnov test will be adopted to test the normality of continuous variables. Comparisons among groups will be performed by using the χ² test and anaylsis of variance, followed by Tukey test (p<0.05). The logistic regression will be applied, and the degrees of this association will be measured using the OR and 95% CI.

ETHICS AND DISSEMINATION

The present protocol was submitted and approved by the Ethical Committee of the University of São Paulo, Bauru, São Paulo, Brazil (CAAE: 79123517.0.0000.5417). Consent for publication will be obtained from all parents or legal guardians. Results of this study will be reported in full through peer-reviewed journals.

TRIAL REGISTRATION NUMBER

RBR-9fsxnn.

Biochemical characterisation of carious dentine zones using Raman spectroscopy

OBJECTIVE

Carious tissue discrimination in clinical operative caries management relies traditionally on the subjective hardness of carious dentine. Biochemical alterations within the lesion have the potential to discriminate the lesion zones objectively. This study aimed to determine the correlation between the biochemical proportions of amide I and phosphate moieties as these are the most prominent peaks found in dentine with the Knoop microhardness of carious dentine zones, using non-contact Raman spectroscopy. The null hypothesis investigated was that there was no correlation between Raman peak ratios, amide I: phosphateν1, and the Knoop microhardness within specific zones of a carious lesion.

METHODS

423 scan points from 20 carious dentine lesion samples examined using high-resolution Raman spectroscopy. The peak ratio of the characteristic vibration mode of amide I (1650 cm^-1) and phosphate (960 cm^-1) bands were calculated, following a straight line path through the lesion to the pulp and correlated to corresponding Knoop microhardness measurements.

RESULTS

Using logistic regression analysis, clear correlations were found between the Knoop microhardness and Raman peak ratio cut-off values between caries-infected and caries-affected dentine (81.5 % sensitivity / 92.7 % specificity), with a lower specificity (2.7 %) found between caries-affected and sound dentine.

CONCLUSION

This study concluded that non-contact Raman spectroscopy can be used in vitro to discriminate objectively between the different zones of a carious dentine lesion at high resolution, using the Raman peak ratios, amide I : phosphate ν₁.

CLINICAL SIGNIFICANCE

Specific biochemical alterations have the potential to be used in-vitro and in-vivo to identify the end-point of selective carious lesion excavation.

Minimally invasive judgement calls: managing compromised first permanent molars in children

This paper aims to update the reader on how minimally invasive (MI) techniques may be used to improve the longevity of carious or defective/compromised first permanent molars (cFPMs) in young children. Clinical and radiographic diagnosis and the prognostic factors will be discussed in view of recent studies showing that these teeth can be kept in function and have an improved prognosis as the child gets older. Clinical protocols for their care, based on the latest evidence and techniques for MI restorations, together with longevity information of possible restorative options, are described. This paper also explores the rationale behind enforced extractions and related morbidity, in order to help oral healthcare practitioners to determine the optimal management of these key elements in the dentition for the benefit of the patients.

Chemo-mechanical characterization of carious dentine using Raman microscopy and Knoop microhardness

One of the aims in the clinical operative management of dental carious lesions is to remove selectively the highly infected and structurally denatured dentine tissue, while retaining the deeper, repairable affected and intact, healthy tissues for long-term mechanical strength. The present study examined the correlation of chemical functional groups and the microhardness through the different depths of a carious lesion using Raman spectroscopy and Knoop microhardness testing. The null hypothesis investigated was that there was no correlation between Raman peak ratios (amide I : phosphate ν1 ) and equivalent Knoop microhardness measurements. Ten freshly extracted human permanent teeth with carious dentine lesions were sectioned and examined using high-resolution Raman microscopy. The ratio of absorbency at the amide I and phosphate bands were calculated from 139 scan points through the depth of the lesions and correlated with 139 juxtaposed Knoop microhardness indentations. The results indicated a high correlation (p < 0.01) between the peak ratio and the equivalent Knoop hardness within carious dentine lesions. This study concluded that Raman spectroscopy can be used as a non-invasive analytical technology for in vitro studies to discriminate the hardness of carious dentine layers using the peak ratio as an alternative to the invasive, mechanical Knoop hardness test.

Success rates of preformed metal crowns placed with the modified and standard hall technique in a paediatric dentistry setting

BACKGROUND

The Hall Technique is a less invasive caries management technique for treating carious primary molars. It has become a routine treatment at specialists' practices.

AIM

To retrospectively evaluate the clinical success and survival rates of preformed metal crowns placed on primary molars using the Hall Technique in a Paediatric Dentistry Setting.

DESIGN

Patient records of children receiving Hall crowns (with or without proximal slicing) between 2011 and 2017 were reviewed. Teeth with no clinical or radiographic evidence of pulp involvement at baseline and at least six months' follow-up were included. Kaplan-Meier survival analyses and Mantel-Cox statistics were carried out.

RESULTS

In total, 181 Hall crowns performed in 2- to 10-year-olds with a mean follow-up period of 22 months were included for analysis. Mean d₃ mft/D₃ MFT was 6.55 ± 3.48/0.18 ± 0.66. The majority of crowns were successful (92.3%; n = 167), four presented at least one minor failure (2.2%; reversible pulpitis, crown lost, or secondary caries) and ten were major failures (5.5%; irreversible pulpitis or abscess). When comparing crowns performed with no tooth preparation to crowns performed with proximal slicing, no differences were observed (P = 0.70, CI = 0.68-0.83).

CONCLUSION

The survival rate and clinical efficacy of Hall crowns were high in a secondary care-based setting. The HT is an effective and less invasive management option for asymptomatic carious primary molars.