Fardad Shakibaie

Differential reflectometry versus tactile sense detection of subgingival calculus in dentistry

Abstract. Detecting dental calculus is clinically challenging in dentistry. This study used typodonts with extracted premolar and molar teeth and simulated gingival tissue to compare the performance of differential reflectometry and periodontal probing. A total of 30 extracted teeth were set in an anatomical configuration in stone to create three typodonts. Clear polyvinyl siloxane impression material was placed to replicate the periodontal soft tissues. Pocket depths ranged from 10 to 15 mm. The three models were placed in a phantom head, and an experienced dentist assessed the presence of subgingival calculus first using the DetecTar (differential reflectometry) and then a periodontal probe. Scores from these two different methods were compared to the gold standard (direct examination of the root surface using 20× magnification) to determine the accuracy and reproducibility. Differential reflectometry was more accurate than tactile assessment (79% versus 60%), and its reproducibility was also higher (Cohen kappa 0.54 versus 0.39). Both methods performed better on single rooted premolar teeth than on multirooted teeth. These laboratory results indicate that differential reflectometry allows more accurate and reproducible detection of subgingival calculus than conventional probing, and supports its use for supplementing traditional periodontal examination methods in dental practice.

Violet and blue light-induced green fluorescence emissions from dental caries

BACKGROUND The objective of this laboratory study was to compare violet and visible blue LED light-elicited green fluorescence emissions from enamel and dentine in healthy or carious states. METHODS Microscopic digital photography was undertaken using violet and blue LED illumination (405 nm and 455 nm wavelengths) of tooth surfaces, which were photographed through a custom-made stack of green compensating filters which removed the excitation light and allowed green fluorescence emissions to pass. Green channel pixel data were analysed. RESULTS Dry sound enamel and sound root surfaces showed strong green fluorescence when excited by violet or blue lights. Regions of cavitated dental caries gave lower green fluorescence, and this was similar whether the dentine in the lesions was the same colour as normal dentine or was darkly coloured. The presence of saliva on the surface did not significantly change the green fluorescence, while the presence of blood diluted in saliva depressed green fluorescence. CONCLUSIONS Using violet or blue illumination in combination with green compensating filters could potentially aid in the assessment of areas of mineral loss.

DIAGNOdent Pen versus tactile sense for detection of subgingival calculus: an in vitro study

The objective of this study is to compare the performance of the DIAGNOdent laser fluorescence (LF) Pen to conventional periodontal probing for detection of subgingival calculus under defined laboratory conditions. Extracted teeth with various levels of subgingival deposits of calculus were mounted anatomically in stone casts, and an impression material was used to replicate periodontal soft tissues. The casts were examined for the presence of subgingival calculus at eight surfaces per tooth (240 sites) using LF and a periodontal probe. Sites were rescored after 1 and 3 weeks. Direct imaging of the root surfaces under magnification was the gold standard. As a result, for an experienced operator, LF was more accurate than tactile assessment (across all sites, 84.0% vs. 59.8%). The performance difference was greater for multi‐rooted teeth (85.8% vs. 56.9%) than single‐rooted teeth (77.2% vs. 66.7%). The performance of LF in this laboratory trial was influenced strongly by clinician skill and experience. When used by an experienced operator, LF was more sensitive (75.1% vs. 69.2%), specific (92.6% vs. 86.3%), and accurate (84% vs. 77.9%) than for an inexperienced operator. In conclusion, under the defined laboratory conditions used, LF had better performance than tactile examination, particularly for multi‐rooted teeth. This method may have value clinically as an adjunct for detecting subgingival deposits of calculus in clinical practice. The usefulness of the method improves with operator experience.

Deconvolution of the particle size distribution of ProRoot MTA and MTA Angelus

Abstract Objective Mineral trioxide aggregate (MTA) cements contain two types of particles, namely Portland cement (PC) (nominally 80% w/w) and bismuth oxide (BO) (20%). This study aims to determine the particle size distribution (PSD) of PC and BO found in MTA. Materials and methods The PSDs of ProRoot MTA (MTA-P) and MTA Angelus (MTA-A) powder were determined using laser diffraction, and compared to samples of PC (at three different particle sizes) and BO. The non-linear least squares method was used to deconvolute the PSDs into the constituents. MTA-P and MTA-A powders were also assessed with scanning electron microscopy. Results BO showed a near Gaussian distribution for particle size, with a mode distribution peak at 10.48 μm. PC samples milled to differing degrees of fineness had mode distribution peaks from 19.31 down to 4.88 μm. MTA-P had a complex PSD composed of both fine and large PC particles, with BO at an intermediate size, whereas MTA-A had only small BO particles and large PC particles. Conclusions The PSD of MTA cement products is bimodal or more complex, which has implications for understanding how particle size influences the overall properties of the material. Smaller particles may be reactive PC or unreactive radiopaque agent. Manufacturers should disclose particle size information for PC and radiopaque agents to prevent simplistic conclusions being drawn from statements of average particle size for MTA materials.

Effect of oral fluids on dental caries detection by the VistaCam

The VistaCam® system (Durr Dental, Bietigheim‐Bissingen, Germany) has been suggested as an adjunct to clinical examination for dental caries. This study assessed whether the digital scores obtained for tooth surfaces were affected by the colour of the carious lesions present and by the presence of saliva or blood on the tooth surface. The VistaCam intra‐oral ries, or with sound enamel and root surfaces, with or without overlying dental plaque biofilm. Teeth that had undergone root treatment or were stained by tetracycline were also assessed. Readings were taken in the dry state and after application of human stimulated saliva or venous blood onto the surface of the samples. VistaCam fluorescence scores for all samples were similar in the dry state, and when covered with saliva (P > 0.05), however a coating of dilute blood elevated the readings for most samples to a high level (P < 0.01), other than tetracycline stained teeth and dental caries (P > 0.05). Readings for healthy enamel were 0.9–1.1, and these increased up to 2.8 in the presence of blood. VistaCam fluorescence scores are not affected by dryness or moisture from the presence of saliva but increase when traces of blood are present. This problem needs to be taken into account when the device is used clinically, because blood from the gingival crevice is a common contaminant of tooth surfaces when patients have widespread gingival inflammation. There are also issues with elevated scores from background fluorescence from tetracyclines, which need to be considered when the system is in clinical use.

Fluorescence imaging of dental restorations using the VistaCam intra-oral camera

Abstract Optical fluorescence imaging methods have a range of forensic applications. The VistaCam system (Dürr Dental) is an existing intra-oral fluorescence camera, which was designed to aid detection of dental caries using 405 nm wavelength light generated by light emitting diodes (LEDs). This study assessed whether this fluorescence imaging device could also be used to recognize dental restorative materials, which is essential for accurate dental charting of deceased persons who are unidentified. The effect of body fluids (saliva and blood) on performance was also assessed. The VistaCam was used on the bench to assess 55 extracted human teeth with restorations, and samples of restorative materials. Readings were first taken in the moist state and then after the application of human saliva or venous blood. Fluorescence scores were compared using one-way ANOVA. Human enamel gave lower fluorescence than restorations. Different tooth-coloured restorative materials gave similar strong fluorescence scores, without statistically significant differences between them. Fluorescence scores were not affected by the presence of ambient fluids (saliva or blood). Using violet 405 nm light to elicit fluorescence may aid in the recognition of dental restorative materials.

Dental calculus detection using the VistaCam

The VistaCam® intra‐oral camera system (Dürr Dental, Bietigheim‐Bissingen, Germany) is a fluorescence system using light emitting diodes that produce a 405‐nm violet light. This wavelength has potential application for detection of dental calculus based on red emissions from porphyrin molecules. This study assessed the digital scores obtained for both supragingival and subgingival calculus on 60 extracted teeth and compared these with lesions of dental caries. It has also examined the effect of saliva and blood on the fluorescence readings for dental calculus. VistaCam fluorescence scores for both supragingival (1.7–3.3) and subgingival calculus (1.3–2.4) were higher than those for sound root surfaces (0.9–1.1) and dental caries (0.9–2.2) (p < .05). The readings for calculus samples were not affected by the presence of saliva or blood. These results suggest that the use of violet light fluorescence could be a possible adjunct to clinical examination for deposits of dental calculus.