Esam Tashkandi

Color difference thresholds in dentistry

PURPOSE The aim of this prospective multicenter study was to determine 50:50% perceptibility threshold (PT) and 50:50% acceptability threshold (AT) of dental ceramic under simulated clinical settings. MATERIALS AND METHODS The spectral radiance of 63 monochromatic ceramic specimens was determined using a non-contact spectroradiometer. A total of 60 specimen pairs, divided into 3 sets of 20 specimen pairs (medium to light shades, medium to dark shades, and dark shades), were selected for psychophysical experiment. The coordinating center and seven research sites obtained the Institutional Review Board (IRB) approvals prior the beginning of the experiment. Each research site had 25 observers, divided into five groups of five observers: dentists-D, dental students-S, dental auxiliaries-A, dental technicians-T, and lay persons-L. There were 35 observers per group (five observers per group at each site ×7 sites), for a total of 175 observers. Visual color comparisons were performed using a viewing booth. Takagi-Sugeno-Kang (TSK) fuzzy approximation was used for fitting the data points. The 50:50% PT and 50:50% AT were determined in CIELAB and CIEDE2000. The t-test was used to evaluate the statistical significance in thresholds differences. RESULTS The CIELAB 50:50% PT was ΔEab  = 1.2, whereas 50:50% AT was ΔEab  = 2.7. Corresponding CIEDE2000 (ΔE00 ) values were 0.8 and 1.8, respectively. 50:50% PT by the observer group revealed differences among groups D, A, T, and L as compared with 50:50% PT for all observers. The 50:50% AT for all observers was statistically different than 50:50% AT in groups T and L. CONCLUSION A 50:50% perceptibility and ATs were significantly different. The same is true for differences between two color difference formulas ΔE00 /ΔEab . Observer groups and sites showed high level of statistical difference in all thresholds. CLINICAL SIGNIFICANCE Visual color difference thresholds can serve as a quality control tool to guide the selection of esthetic dental materials, evaluate clinical performance, and interpret visual and instrumental findings in clinical dentistry, dental research, and subsequent standardization. The importance of quality control in dentistry is reinforced by increased esthetic demands of patients and dental professionals.

Volumetric measurements of removed tooth structure associated with various preparation designs.

The amount of tooth structure that is removed as a consequence of tooth preparation has rarely been quantified. The aim of this study was to quantify the volume of reduction of tooth structure associated with different commonly used preparation designs. Eighty extracted teeth were divided into eight groups according to the type of preparation design and tooth type. Each specimen underwent pre- and post preparation scanning using microcomputed tomography. The volume of the resultant tooth structure removed was analyzed. Significant differences in the amount of tooth structure removal were noted between types of coverage and types of teeth.

Consistency in color parameters of a commonly used shade guide.

OBJECTIVE The use of shade guides to assess the color of natural teeth subjectively remains one of the most common means for dental shade assessment. Any variation in the color parameters of the different shade guides may lead to significant clinical implications. Particularly, since the communication between the clinic and the dental laboratory is based on using the shade guide designation. The purpose of this study was to investigate the consistency of the L∗a∗b∗ color parameters of a sample of a commonly used shade guide. MATERIALS AND METHODS The color parameters of a total of 100 VITAPAN Classical Vacuum shade guide (VITA Zahnfabrik, Bad Säckingen, Germany(were measured using a X-Rite ColorEye 7000A Spectrophotometer (Grand Rapids, Michigan, USA). Each shade guide consists of 16 tabs with different designations. Each shade tab was measured five times and the average values were calculated. RESULTS The ΔE between the average L∗a∗b∗ value for each shade tab and the average of the 100 shade tabs of the same designation was calculated. Using the Student t-test analysis, no significant differences were found among the measured sample. CONCLUSION There is a high consistency level in terms of color parameters of the measured VITAPAN Classical Vacuum shade guide sample tested.

To publish or not to publish, that is the question.

In an era of rapid technologic advancement in the world of communication, social networking, instant messaging, Facebook, Twitter, etc., it is virtually impossible to be isolated even if you want to be. The whole paradigm of obtaining information and the power it brings has shifted. Seeking information used to be a laborious task, but now information is just a few clicks away. But how does this relate to the publishing of dental research? Simply speaking, the dental student or clinician who is the end-user – the consumer of the published word – has become more astute and more demanding. Hence, it behooves dental educators and researchers who wish to publish to cater to the needs of these stake-holders. These people want accurate and reliable information – and they want it now. With Google becoming an actual verb (“I will google it”) the reader is bombarded with a tsunami of sources for information and the onus is on him or her to judge the accuracy and reliability of the obtained information. Take Wikipedia as an example; anyone can upload information in a very dynamic fashion. Even if one wants to get information about a certain clinical procedure or technique, a quick search will provide not only a multitude of written explanations, but more often than not several videos showing in a very graphical way how it’s done. This applies equally to whether you want to know how to make bread from scratch or clean the track ball of your blackberry. But going back to the subject of dental publishing, yes I would like to publish but I will be very picky when it comes to which journal I will submit my manuscript to. Of prime importance, I would like to know in which and how many indexing services the journal is available in. There are a plethora of such services like Medline, PubMed and Scopus to name a few. I obviously want my paper to be as widely accessible as possible. I challenge any author to deny that he or she gets a kick out of learning that his or her paper has been cited. After all, is not it all about the dissemination of information and knowledge? Moreover, many of the reputable publishers will now alert the author when their work has been cited elsewhere. So let this be an open and standing invitation to all the readers to become inspired to actually participate and become authors themselves and to embark on sound research projects which can in turn be published. It is only with the economics of knowledge that nations advance and develop. What might seem as such an insurmountable task is actually a wonderful and rewarding journey. It all usually starts with a simple idea and then when you read the final product you say to yourself, “Why did not I think of that?”