An in vitro comparison of fluorescence-aided caries excavation and conventional excavation by microhardness testing

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.

Does the heat generated by fluorescence-aided caries excavation system effect the pulp temperature of primary teeth irreversibly? An in-vitro evaluation of the temperature changes in the pulp chamber

Background

This study aimed to analyze the effect of the Fluorescence Aided Caries Excavation (FACE) and the remaining dentin thickness on the temperature changes of the pulp chamber.

Material and Methods

Freshly extracted deciduous molars and a pulpal microcirculation model were used in the study. The sample size was calculated according to power analyses (power at 90%) based on previous studies. Thus, 40 samples were needed. Standard cavities (3x3 mm) were designed to obtain a 2 mm distance through to the pulp chamber, and in each tooth (n=10), these cavities were modified to obtain 1.5 mm, 1mm, and 0.5 mm final distance through to the pulp. Coronal parts of the teeth were placed on an acrylic plate with three gaps for feeding and extraction needles and the thermocouple. The temperature changes were recorded from the initial time to 15 s and 30 s,1 min, 1.5 min, 2 min, 2.5 min, 3 min intervals.

Results

The results showed that hence the thickness between cavity floor and pulp chamber was decreased, and application time of FACE was increased, an increase in temperature changes was detected. However, the recorded values were not mean to cause irreversible damages to the pulp chamber.

Conclusions

The recent study showed that Face is an appropriate caries detecting system that does not affect the pulp chamber's health, and it can be safely used in the primary teeth. Key words:Caries assessment, dental caries, dental pulp, pediatric dentistry.

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.

Microhardness and shear bond-strength of carious dentin after fluorescence-aided or conventionally excavation: (An in-vitro comparison)

Background

To compare the fluorescence-aided and conventionally excavated dentin with microhardness and shear bond strength(SBS) tests.

Material and Methods

Twenty-four teeth with dentin caries were bisected through the center of the lesion into two halves. Forty-eight dentin specimens were embedded and mounted in an acrylic resin. All carious tissue was removed and classified as caries free using conventional visual tactile criteria. Then half of the specimens(n=24) were reinspected with fluorescence-aided caries excavation light(FACE) (FaceLight, W&H Dentalwerk, Bürmoos GmbH, Austria). Specimens were subjected to microhardness and shear bond strength testings. The fracture mode analysis was also performed. The data were compared with Student's t test and Chi-square test.

Results

Residual caries was observed in 2 out of 24 conventionally excavated specimens with FACE inspection(p>0.05). Mean Vickers hardness of the dentin was 61.5±5 in the FACE group and 70.3±3 kg/mm2 in the conventionally excavated group(p>0.05). The mean SBS value of FACE group was 11.42±1.63 MPa and 18.27±1.43 MPa in conventionally excavated group. There was no statistically significant difference between conventional and FACE groups for microhardness and SBS tests(p>0.05). There were also no significant differences on the fracture mode distributions of the groups(p>0.05).

Conclusions

FACE method could be considered as a promising technique for removing infected dentin. Key words:FACE, conventional excavation, residual caries detection, shear bond strength, microhardness.

The interrelationship of microstructure and hardness of human coronal dentin using reference point indentation technique and micro-Raman spectroscopy

OBJECTIVES

The aim of this paper is to determine the interrelationship between the microstructure - in terms of chemical composition and crystallinity - to the microhardness of coronal dentin.

METHODS

Dentin microhardness was tested by a novel reference point indenter and compared to the traditional Knoop hardness method. Micro-Raman spectroscopy was used to determine the chemical composition and crystallinity of dentin.

RESULTS

From the occlusal groove to the border of the coronal pulp chamber, dentin hardness decreased from superficial dentin (SD) to deep dentin (DD). Mineral/organic matrix ratios (phosphate/CH and phosphate/amide I) also decreased from SD to DD; however, this change was significant (P<0.05) in the phosphate/amide I ratio only. The phosphate/carbonate ratio decreased significantly by varying position from SD to DD. The degree of the crystallinity, as measured by the full width at half maximum (FWHM) of the peak at 960cm^-1, decreased significantly going from superficial to deep dentin.

SIGNIFICANCE

For the first time, the interrelationship between the microstructure and the mechanical properties of coronal dentin was determined by using the novel reference point indentation technique and micro-Raman spectroscopy. We hypothesize that the decrease in hardness from superficial to deep dentin can potentially be explained by decreased mineral content and increased carbonate content, which is also associated with decreased crystallinity. Collectively, there is a positive association between dentin hardness and mineral content and a negative association between dentin hardness and carbonate content.

Comparison of two different methods of detecting residual caries

Objectives

The aim of this study was to investigate the ability of the fluorescence-aided caries excavation (FACE) device to detect residual caries by comparing conventional methods in vivo.

Materials and Methods

A total of 301 females and 202 males with carious teeth participated in this study. The cavity preparations were done by grade 4 (Group 1, 154 teeth), grade 5 (Group 2, 176 teeth), and postgraduate (Group 3, 173 teeth) students. After caries excavation using a handpiece and hand instruments, the presence of residual caries was evaluated by 2 investigators who were previously calibrated for visual-tactile assessment with and without magnifying glasses and trained in the use of a FACE device. The tooth number, cavity type, and presence or absence of residual caries were recorded. The data were analyzed using the Chi-square test, the Fisher's Exact test, or the McNemar test as appropriate. Kappa statistics was used for calibration. In all tests, the level of significance was set at p = 0.05.

Results

Almost half of the cavities prepared were Class II (Class I, 20.9%; Class II, 48.9%; Class III, 20.1%; Class IV, 3.4%; Class V, 6.8%). Higher numbers of cavities left with caries were observed in Groups 1 and 2 than in Group 3 for all examination methods. Significant differences were found between visual inspection with or without magnifying glasses and inspection with a FACE device for all groups (p < 0.001). More residual caries were detected through inspection with a FACE device (46.5%) than through either visual inspection (31.8%) or inspection with a magnifying glass (37.6%).

Conclusions

Within the limitations of this study, the FACE device may be an effective method for the detection of residual caries.