Assessment of Smear Layer Formation After Caries Removal Using Erbium Laser and Papain-Based Chemo-Mechanical Caries Removal Agent: An In Vitro Scanning Electron Microscopy Study

Introduction With the advancement in the field of adhesive dentistry, there has been a significant and groundbreaking shift toward the adoption of minimally invasive caries removal techniques where substrate modification is known to enhance adhesive bonding. The smear layer has always been controversial, as its modification helps in bonding, but if contaminated with bacteria, it compromises the formation of a satisfactory marginal seal. Thus, the recognition of the role played by the smear layer highlights the importance of the type of caries removal method employed. Hence, the aim of the present study was to assess and compare smear layer formation after caries removal using an erbium laser and chemo-mechanical caries removal agent by scanning electron microscopy. Methods The study involved the evaluation of 30 extracted human molars with occlusal caries. Based on the method of caries excavation, the samples were allocated into two separate groups: group 1 - caries removed using erbium laser (Waterlase, Biolase, Lake Forest, CA); group 2 - caries removed using papain-based chemo-mechanical caries removal agent (Carie Fix, Dengen Dental, Bahadurgarh, India). To assess the smear layer, the samples underwent examination using a scanning electron microscope at 1500x and 3000x magnification after removal of caries. Statistical analysis was done using SPSS version 22 software (IBM Corp., Armonk, NY). Mann-Whitney test was used to compare the mean smear layer (nonparametric) between both groups. Results Group 1 (Er:YAG laser) showed significantly greater removal of the smear layer than group 2 (papain-based chemo-mechanical caries removal agent) on the excavated caries surfaces (p < 0.001). In group 1, the dentinal tubules exhibited greater patency when compared to the partial patency observed in group 2. Conclusion Both techniques for caries removal were effective; however, the Er:YAG laser method was determined to be more efficient in comparison to the chemo-mechanical agent. These caries removal methods can be considered the future of minimally invasive dentistry.

Using Antimicrobial Photodynamic Therapy with Ultrasound Devices and Bioactive Glasses as a Combined Approach for Treating Dentin Caries Lesions

Novel approaches for caries lesion removal and treatment have been proposed. This study evaluates the combined use of an experimental ultrasound, aPDT (antimicrobial photodynamic therapy) and bioactive glasses on the removal, decontamination and remineralization of dentin caries lesions. A biological model created with a duo species biofilm (Streptococcus mutans and Lactobacillus acidophilus) was used for the development of a caries-like lesion over the dentin for 7 days. Bovine dentin specimens (4 × 4 × 2 mm) were randomized according to the following caries removal techniques: bur (BUR) or ultrasound (ULT), decontamination (with or without aPDT) and remineralization materials (45S5 or F18 bioactive glasses). The following different groups were investigated: caries lesion (control); sound dentin (control); BUR; BUR + aPDT; ULT; ULT + aPDT; BUR + 45S5, BUR + F18; ULT + 45S5; ULT + F18; BUR + aPDT + 45S5; BUR + aPDT + F18; ULT + aPDT + 45S5; and ULT + aPDT + F18. Transverse microradiography (TMR), cross-sectional microhardness (CSH), FT-Raman spectroscopy and confocal microscopy (CLSM) were performed. A two-way ANOVA and Tukey's test were used (α = 0.05). (3) Results: The TMR revealed a lesion depth of 213.9 ± 49.5 μm and a mineral loss of 4929.3% vol.μm. The CSH increases as a function of depth, regardless of the group (p < 0.05). Removal with BUR (24.40-63.03 KHN) has a greater CSH than ULT (20.01-47.53 KHN; p < 0.05). aPDT did not affect the CSH (p > 0.05). No difference was observed between 45S5 or F18 (p > 0.05), but a change was observed for ULT (p > 0.05). The FT-Raman shows no differences for the phosphate (p > 0.05), but a difference is observed for the carbonate and C-H bonds. The CLSM images show that aPDT effectively inactivates residual bacteria. A combination of ULT, aPDT and bioactive glasses can be a promising minimally invasive treatment.

Pilot study assessing 3D-printed teeth as a caries removal teaching tool

INTRODUCTION

In UK universities, caries removal teaching utilises plastic teeth. This format does not enable students to learn how to distinguish between tooth layers and caries via tactile feedback. The aim of this study was to assess the applicability of a novel, 3D-printed carious tooth within caries removal teaching.

MATERIALS AND METHODS

Single-material 3D-printed teeth containing simulated tactile caries were developed and 14 final-year undergraduates were briefed to remove caries and minimise damage to healthy tissue within the tooth. Students completed evaluation questionnaires for their opinion of 3D-printed teeth in comparison to plastic teeth and perceived confidence to subsequently treat patients. Cavity preparation perimeters were measured, using photographs with a standard protocol. Heat map analysis illustrated variation in location and extent of cavity preparations produced by the cohort.

RESULTS

Student feedback indicated the 3D-printed caries exercise was positively received, 71.4% agreed 3D-printed teeth would have better prepared students for patient treatment; 78.6% rated their preclinical stress/anxiety as 'very high' or 'high' and 57.1% agreed that if preclinical teaching incorporated 3D-printed teeth, their stress/anxiety when treating their first caries patient would have been reduced. The average perimeter of cavity preparation indicated relative variation, with a maximum perimeter of 19.6 mm and a minimum of 10.7 mm, and a range of 8.9 mm.

DISCUSSION

Introducing 3D-printed teeth into preclinical teaching would allow students to gain confidence in clinically relevant experience in tactile aspects of caries treatment earlier in their training than currently possible.

CONCLUSION

This study demonstrates student acceptance of an alternative caries removal teaching method, with potential to increase aptitude in caries removal in a clinically relevant manner.

Selective removal compared to complete removal for deep carious lesions

INTRODUCTION

Dental caries have been conventionally managed by non-selective removal of carious tissue (total complete removal); however, the adverse effects of this procedure have promoted the use of conservative caries removal techniques (selective removal), but there is still controversy regarding its effectiveness.

METHODS

We searched in Epistemonikos, the largest database of systematic reviews in health, which is maintained by screening multiple information sources, including MEDLINE, EMBASE, Cochrane, among others. We extracted data from the systematic reviews, reanalyzed data of primary studies, conducted a meta-analysis and generated a summary of findings table using the GRADE approach.

RESULTS AND CONCLUSIONS

We identified seven systematic reviews including seven studies overall, of which all were randomized trials. We concluded that selective caries removal may decrease the need for root canal treatment and the risk of pulp exposure in teeth with deep caries, but the certainty of the evidence is low. It is not clear whether the selective removal of caries reduces the risk of appearance of signs and symptoms of pulp disease and the risk of restorations failure, as the certainty of the evidence is very low.

Evaluation of the Efficacy of Visual, Tactile Method, Caries Detector Dye, and Laser Fluorescence in Removal of Dental Caries and Confirmation by Culture and Polymerase Chain Reaction: An In Vivo Study

Aim

To determine the degree of association between visual and tactile methods of caries removal compared with caries detector dye and laser fluorescence device (DIAGNOdent), which detects the degree of demineralization; to determine the presence of Streptococcus mutans via culture and polymerase chain reaction (PCR) techniques; and to find a suitable method for caries removal.

Materials and Methods

A total of 75 patients were divided into three groups: visual and tactile (Group A), visual and tactile with caries detector dye (Group B), and visual and tactile with caries detector dye along with laser florescence readings (Group C). Caries removal was carried out using visual and tactile methods, caries detector dye, and laser fluorescence, and the samples obtained were subjected to culture and PCR. The data obtained were statistically analyzed using Pearson's chi-square test, analysis of variance (ANOVA), and Tukey's post hoc test.

Results

Visual and tactile along with caries detector dye and laser florescence (Group C) is the most efficient method for caries removal.

Conclusion

Caries detector dye along with visual, tactile examination and laser fluorescence is a valuable and superior tool for clinicians that aids in better caries removal and can prevent the overzealous removal of tooth structure.

Selective Ablation of Carious Lesions using an Integrated Near-IR Imaging System and a Novel 9.3-µm CO2 Laser

Previous studies have shown that reflectance imaging at wavelengths greater than 1200-nm can be used to image demineralization on tooth occlusal surfaces with high contrast and without the interference of stains. In addition, these near-IR imaging systems can be integrated with laser ablation systems for the selective removal of carious lesions. Higher wavelengths, such as 1950-nm, yield higher lesion contrast due to higher water absorption and lower scattering. In this study, a point-to-point scanning system employing diode and fiber lasers operating at 1450, 1860, 1880, and 1950-nm was used to acquire reflected light images of the tooth surface. Artificial lesions were imaged at these wavelengths to determine the highest lesion contrast. Near-IR images at 1880-nm were used to demarcate lesion areas for subsequent selective carious lesion removal using a new compact air-cooled CO₂ laser prototype operating at 9.3-µm. The highest lesion contrast was at 1950-nm and the dual NIR/CO₂ laser system selectively removed the simulated lesions with a mean loss of only 12-µm of sound enamel.

Evaluation of dental explorer and visual inspection for the detection of residual caries among Greek dentists

Objectives

The objective of this study was to assess the effect of the operator's degree of clinical experience on the residual caries diagnosis through visual inspection and tactile sensation.

Materials and Methods

The participants were asked about the years of their clinical practice, any further training concerning cariology, their familiarity with the minimal invasive philosophy, and the techniques that they use to remove dental caries and detect when to stop the removal of carious tissues. In addition, an in vitro diagnostic test was conducted. Carious teeth were excavated to a level selected in random. Teeth were examined by each participant individually. Initial examination was performed by visual inspection. Subsequently, a dental explorer was used concerning the potential need for further removal of dental tissues. A sample of 380 dentists and dental school students were selected for the purposes of this study.

Results

Dental students presented statistically significant better sensitivity, than dentists from both age groups, during both visual inspection and tactile sensation of residual caries. Participants' ability to diagnose residual caries during cavity preparation was independent of their years of experience.

Conclusions

During the removal of carious lesions, with the goal of limiting the sacrifice of healthy structures and the leftover of residual caries, clinicians should combine a selective removal technique and the attentive visual inspection, with at least one further diagnostic method, aside from the dental explorer. Tactile examination of residual caries solely with the dental explorer must be used with attention.

Image-guided Removal of Interproximal Lesions with a CO2 Laser

Recent studies have shown that near-IR (NIR) imaging methods such as NIR reflectance can be used to image lesions on proximal surfaces, and optical coherence tomography (OCT) can be used to measure the depth of those lesions below the tooth surface. These imaging modalities can be used to acquire high contrast images of demineralized tooth surfaces, and 2-D and 3-D images can be extracted from this data. At NIR wavelengths longer than 1200-nm, there is no interference from stains and the contrast is only due to the increased light scattering of the demineralization. Previous studies have shown that image-guided laser ablation can be used to remove occlusal lesions, but its use for the removal of subsurface lesions on proximal surfaces has not been investigated. The objective of this study is to demonstrate that simultaneously scanned NIR and CO2 lasers can be used to selectively remove natural and artificial interproximal caries lesions with minimal damage to sound tooth structure. In this study, images of simulated and natural interproximal lesions on extracted teeth were imaged using a digital microscope, a scanned 1460-nm superluminescent laser diode with an InGaAs detector and a cross polarization OCT system operating at 1300-nm. The lesions were subsequently removed with a CO2 laser operating at 9.3-µm and the dental handpiece and the volume of sound tissue removed was compared.

Exploring How U.S. Dental Schools Teach Removal of Carious Tissues During Cavity Preparations

Approaches for managing carious tissues during cavity preparations vary considerably among clinicians, which may reflect inconsistencies in the teaching of this subject by dental schools. The aims of this study were to investigate practices related to the preclinical and clinical teaching of caries removal at U.S. dental schools and the relationship between that teaching and requirements for U.S. dental licensure examinations. The electronic survey included questions about terminology, methods, instruments and materials, treatment planning, criteria for clinical exams, faculty calibration sessions, and licensure exams. The faculty members at U.S. dental schools responsible for teaching cariology were invited to participate; 54 of the 65 schools had identified a contact person at the time of the survey in October 2015. Of those 54 invited to participate, 43 completed the survey (response rate of 79.6%). Most of the respondents indicated that depth of carious lesions was a clinical determinant of the amount of carious dentin being removed in cavity preparations. Caries removal was used as a criterion in restorative clinical examinations by 95% of responding schools. Marked differences were observed regarding the criteria used for assessment and removal of carious tissues, management of deep carious lesions, and definition of "caries remaining at cavity preparations," which is considered a critical error on licensure exams. Faculty calibration sessions on caries removal were reported to occur in 65% of these schools and at different time frames. Overall, the study found a wide range of teaching practices related to caries removal. Best evidence in caries management needs to be aligned with teaching and the criteria used to calibrate faculty members and examiners.

Chemomechanical caries removal method versus mechanical caries removal methods in clinical and community-based setting: A comparative in vivo study

Objective:

To compare the effectiveness of various caries removal techniques in mandibular primary molars using Smart Burs, atraumatic restorative technique (ART) (mechanical caries removal) and Carie-care (chemomechanical caries removal [CMCR]) among primary school children in clinical and community-based settings.

Materials and Methods:

A total of 80 carious primary mandibular molars were selected for the study from the dental clinic and community. They were equally assigned to four groups according to caries removal technique and also by the operating site. In Group 1, caries was removed using Carie-care in the dental clinic and in Group 2, with Smart Burs in the dental clinic. In Group 3, caries was removed using Carie-care in the field and in Group 4, with the ART in the field. The time taken for caries removal, the efficacy of caries removal and patient acceptance were evaluated with different caries removal techniques.

Statistical Analysis:

The obtained data were subjected to statistical analysis by ANOVA test.

Results:

In clinical settings, Carie-care was time-consuming but was more efficient with increased acceptance than Smart Burs and the result was found to be significant statistically (P < 0.05). In community-based settings, Carie-care was more efficient, less time consuming, and showed an increased acceptance when compared to atraumatic restorative treatment and the result was found to be significant statistically (P < 0.05).

Conclusions:

The CMCR technique was superior to the mechanical caries removal technique in primary teeth among school children in terms of time, efficacy, and acceptance in both clinical- and community-based settings.

Selective removal of esthetic composite restorations with spectral guided laser ablation

Dental composites are used for a wide range of applications such as fillings for cavities, adhesives for orthodontic brackets, and closure of gaps (diastemas) between teeth by esthetic bonding. Anterior restorations are used to replace missing, diseased and unsightly tooth structure for both appearance and function. When these restorations must be replaced, they are difficult to remove mechanically without causing excessive removal or damage to enamel because dental composites are color matched to teeth. Previous studies have shown that CO₂ lasers have high ablation selectivity and are well suited for removal of composite on occlusal surfaces while minimizing healthy tissue loss. A spectral feedback guidance system may be used to discriminate between dental composite and dental hard tissue for selective ablation of composite material. The removal of composite restorations filling diastemas is more challenging due to the esthetic concern for anterior teeth. The objective of this study is to determine if composite spanning a diastema between anterior teeth can be removed by spectral guided laser ablation at clinically relevant rates with minimal damage to peripheral healthy tissue and with higher selectivity than a high speed dental hand-piece.

Selective removal of demineralized enamel using a CO2 laser coupled with near-IR reflectance imaging

Detection and diagnosis of early dental caries lesions can be difficult due to variable tooth coloration, staining of the teeth and poor contrast between sound and demineralized enamel. These problems can be overcome by using near-infrared (NIR) imaging. Previous studies have demonstrated that lasers can be integrated with NIR imaging devices, allowing image-guided ablation. The aim of this study was to demonstrate that NIR light at 1500 - 1700 nm can be used to guide a 9.3-μm CO₂ laser for the selective ablation of early demineralization on tooth occlusal surfaces. The occlusal surfaces of ten sound human molars were used in this in-vitro study. Shallow simulated caries lesions of varying depth and position were produced on tooth occlusal surfaces using a demineralization solution. Sequential NIR reflectance images at 1500 - 1700 nm were used to guide the laser for selective ablation of the lesion areas. Digital microscopy and polarization sensitive optical coherence tomography (PS-OCT) were used to assess the selectivity of removal. This study demonstrates that high contrast NIR reflectance images can be used for the image-guided laser ablation of early demineralization from tooth occlusal surfaces.

Do educational methods affect students' ability to remove artificial carious dentine? A randomised controlled trial

This trial aimed to evaluate the influence of two educational methods on students' ability to remove artificial carious dentine. Traditional lecture and lecture plus a live demonstration of artificial carious tissue removal were compared in a blind two-parallel-group design. Twenty-six students were randomly divided into two groups, and their skills were evaluated according to the following criteria: time spent on the dentine excavation procedure (in min), students' perceived confidence in conducting the procedure (graded assessed on a scale from 0 to 10), and the outcome of artificial carious tissue removal, evaluated by measuring the residual dyed artificial carious dentine layer (in μm). Statistical analyses were carried out using a t-test to compare the students' confidence and time spent on the procedure, and a two-way ANOVA was used to compare residual artificial decayed dentine with educational methods and tooth region (incisal, medium, and cervical thirds) as factors. There were no differences between the methods regarding excavation time (P = 0.898) and students' confidence (P = 0.382). The residual artificial carious dentine results showed that the educational method (P < 0.001) and cavity region (P < 0.001) were statistically significant, as was their interaction (P = 0.040). The lecture plus live demonstration group presented the best results for artificial caries removal. Although there were no differences between the two groups for the cervical region, the best results for the lecture plus live demonstration group was in the other two-thirds of the tooth.