Journal of Clinical and Diagnostic Research, ISSN - 0973 - 709X

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Sanjay Gandhi institute of trauma and orthopedics,
On Aug 2018

Dr. Mamta Gupta,
"It gives me great pleasure to be associated with JCDR, since last 2-3 years. Since then I have authored, co-authored and reviewed about 25 articles in JCDR. I thank JCDR for giving me an opportunity to improve my own skills as an author and a reviewer.
It 's a multispecialty journal, publishing high quality articles. It gives a platform to the authors to publish their research work which can be available for everyone across the globe to read. The best thing about JCDR is that the full articles of all medical specialties are available as pdf/html for reading free of cost or without institutional subscription, which is not there for other journals. For those who have problem in writing manuscript or do statistical work, JCDR comes for their rescue.
The journal has a monthly publication and the articles are published quite fast. In time compared to other journals. The on-line first publication is also a great advantage and facility to review one's own articles before going to print. The response to any query and permission if required, is quite fast; this is quite commendable. I have a very good experience about seeking quick permission for quoting a photograph (Fig.) from a JCDR article for my chapter authored in an E book. I never thought it would be so easy. No hassles.
Reviewing articles is no less a pain staking process and requires in depth perception, knowledge about the topic for review. It requires time and concentration, yet I enjoy doing it. The JCDR website especially for the reviewers is quite user friendly. My suggestions for improving the journal is, more strict review process, so that only high quality articles are published. I find a a good number of articles in Obst. Gynae, hence, a new journal for this specialty titled JCDR-OG can be started. May be a bimonthly or quarterly publication to begin with. Only selected articles should find a place in it.
An yearly reward for the best article authored can also incentivize the authors. Though the process of finding the best article will be not be very easy. I do not know how reviewing process can be improved. If an article is being reviewed by two reviewers, then opinion of one can be communicated to the other or the final opinion of the editor can be communicated to the reviewer if requested for. This will help one’s reviewing skills.
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Dr. Mamta Gupta
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Aug 2018

Dr. Rajendra Kumar Ghritlaharey

"I wish to thank Dr. Hemant Jain, Editor-in-Chief Journal of Clinical and Diagnostic Research (JCDR), for asking me to write up few words.
Writing is the representation of language in a textual medium i e; into the words and sentences on paper. Quality medical manuscript writing in particular, demands not only a high-quality research, but also requires accurate and concise communication of findings and conclusions, with adherence to particular journal guidelines. In medical field whether working in teaching, private, or in corporate institution, everyone wants to excel in his / her own field and get recognised by making manuscripts publication.

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Salient features of the JCDR: It is a biomedical, multidisciplinary (including all medical and dental specialities), e-journal, with wide scope and extensive author support. At the same time, a free text of manuscript is available in HTML and PDF format. There is fast growing authorship and readership with JCDR as this can be judged by the number of articles published in it i e; in Feb 2007 of its first issue, it contained 5 articles only, and now in its recent volume published in April 2011, it contained 67 manuscripts. This e-journal is fulfilling the commitments and objectives sincerely, (as stated by Editor-in-chief in his preface to first edition) i e; to encourage physicians through the internet, especially from the developing countries who witness a spectrum of disease and acquire a wealth of knowledge to publish their experiences to benefit the medical community in patients care. I also feel that many of us have work of substance, newer ideas, adequate clinical materials but poor in medical writing and hesitation to submit the work and need help. JCDR provides authors help in this regards.
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Indexation and online availability: Indexation transforms the journal in some sense from its local ownership to the worldwide professional community and to the public.JCDR is indexed with Embase & EMbiology, Google Scholar, Index Copernicus, Chemical Abstracts Service, Journal seek Database, Indian Science Abstracts, to name few of them. Manuscriptspublished in JCDR are available on major search engines ie; google, yahoo, msn.
In the era of fast growing newer technologies, and in computer and internet friendly environment the manuscripts preparation, submission, review, revision, etc and all can be done and checked with a click from all corer of the world, at any time. Of course there is always a scope for improvement in every field and none is perfect. To progress, one needs to identify the areas of one's weakness and to strengthen them.
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Thanking you
With sincere regards
Dr. Rajendra Kumar Ghritlaharey, M.S., M. Ch., FAIS
Associate Professor,
Department of Paediatric Surgery, Gandhi Medical College & Associated
Kamla Nehru & Hamidia Hospitals Bhopal, Madhya Pradesh 462 001 (India)
On May 11,2011

Dr. Shankar P.R.

"On looking back through my Gmail archives after being requested by the journal to write a short editorial about my experiences of publishing with the Journal of Clinical and Diagnostic Research (JCDR), I came across an e-mail from Dr. Hemant Jain, Editor, in March 2007, which introduced the new electronic journal. The main features of the journal which were outlined in the e-mail were extensive author support, cash rewards, the peer review process, and other salient features of the journal.
Over a span of over four years, we (I and my colleagues) have published around 25 articles in the journal. In this editorial, I plan to briefly discuss my experiences of publishing with JCDR and the strengths of the journal and to finally address the areas for improvement.
My experiences of publishing with JCDR: Overall, my experiences of publishing withJCDR have been positive. The best point about the journal is that it responds to queries from the author. This may seem to be simple and not too much to ask for, but unfortunately, many journals in the subcontinent and from many developing countries do not respond or they respond with a long delay to the queries from the authors 1. The reasons could be many, including lack of optimal secretarial and other support. Another problem with many journals is the slowness of the review process. Editorial processing and peer review can take anywhere between a year to two years with some journals. Also, some journals do not keep the contributors informed about the progress of the review process. Due to the long review process, the articles can lose their relevance and topicality. A major benefit with JCDR is the timeliness and promptness of its response. In Dr Jain's e-mail which was sent to me in 2007, before the introduction of the Pre-publishing system, he had stated that he had received my submission and that he would get back to me within seven days and he did!
Most of the manuscripts are published within 3 to 4 months of their submission if they are found to be suitable after the review process. JCDR is published bimonthly and the accepted articles were usually published in the next issue. Recently, due to the increased volume of the submissions, the review process has become slower and it ?? Section can take from 4 to 6 months for the articles to be reviewed. The journal has an extensive author support system and it has recently introduced a paid expedited review process. The journal also mentions the average time for processing the manuscript under different submission systems - regular submission and expedited review.
Strengths of the journal: The journal has an online first facility in which the accepted manuscripts may be published on the website before being included in a regular issue of the journal. This cuts down the time between their acceptance and the publication. The journal is indexed in many databases, though not in PubMed. The editorial board should now take steps to index the journal in PubMed. The journal has a system of notifying readers through e-mail when a new issue is released. Also, the articles are available in both the HTML and the PDF formats. I especially like the new and colorful page format of the journal. Also, the access statistics of the articles are available. The prepublication and the manuscript tracking system are also helpful for the authors.
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Overall, the publishing process with JCDR has been smooth, quick and relatively hassle free and I can recommend other authors to consider the journal as an outlet for their work."

Dr. P. Ravi Shankar
KIST Medical College, P.O. Box 14142, Kathmandu, Nepal.
On April 2011

Dear team JCDR, I would like to thank you for the very professional and polite service provided by everyone at JCDR. While i have been in the field of writing and editing for sometime, this has been my first attempt in publishing a scientific paper.Thank you for hand-holding me through the process.

Dr. Anuradha
On Jan 2020

Important Notice

Original article / research
Year : 2022 | Month : October | Volume : 16 | Issue : 10 | Page : ZC17 - ZC24 Full Version

Comparison of Optical Properties of Clear Aligners Before and After In-vivo Aging

Published: October 1, 2022 | DOI:
Binu Punnoose Gold, Duraisamy Sangeetha, Ravi Kannan

1. Postgraduate Student, Department of Orthodontics and Dentofacial Orthopaedics, SRM Dental College, Chennai, Tamil Nadu, India. 2. Professor, Department of Orthodontics and Dentofacial Orthopaedics, SRM Dental College, Chennai, Tamil Nadu, India. 3. Head, Department of Orthodontics and Dentofacial Orthopaedics, SRM Dental College, Chennai, Tamil Nadu, India.

Correspondence Address :
Dr. Sangeetha Duraisamy,
Professor, Department of Orthodontics and Dentofacial Orthopaedics, SRM Dental College, Chennai, Tamil Nadu, India.


Introduction: There is a rising demand for clear aligners among orthodontic patients and after the expiry of invisalign patent many indigenous aligners have been introduced in several part of the globe including India. The major advantage of the aligners is its invisibility which is attributed to its unique optical properties. The optical properties vary between different aligners and any changes in the optical properties during the clinical use is an important factor to be considered.

Aim: To evaluate and compare the optical properties of three different types of indigenous clear orthodontic aligners before and after in-vivo aging.

Materials and Methods: A prospective clinical study was conducted in the Department of Orthodontics and Dentofacial Orthopaedics, SRM Dental College, Chennai, Tamil Nadu, India, from August to December 2021. Total 36 volunteers participated in the study and were divided into three study groups. In group A subjects had Clearbite aligners (JJ Orthodontics Pvt. Ltd, Thrissur, Kerala), group B had Dentcare clear aligners (Dent Care Dental Lab Pvt. Ltd. Ernakulum, Kerala) and group C had Smile aligners (smile aligners Inc. Mumbai, Maharashtra). Polyvinyl siloxane impression of the maxillary arch was obtained and sent for the fabrication of two sets of clear aligners. One set of aligners were used to measure absorbance and transmittance before invivo aging and another set after an intraoral use of 14 days. The measurement of absorbance and transmittance were made at the wavelength range of 400-700 nm using a Shimadzu UV-3600i Plus UV-Vis-NIR spectrophotometer. Intergroup and intragroup comparisons were done using Independent sample t-test and One-way Analysis of Variance (ANOVA).

Results: In all the three groups of aligners evaluated, an increase in the absorbance values was noted at all the wavelengths after in-vivo aging but the increase was not statistically significant (p-value >0.05). Transmittance values of group A samples reduced after in-vivo aging but not significantly, whereas group B values reduced significantly between 400-440 nm (p-value <0.05) and group C values reduced significantly between 400-460 nm and 680-700 nm (p-value <0.05). Intergroup comparison of the mean absorbance and transmittance values of the group A, B and C samples before and after in-vivo aging showed no significant difference at all wavelengths (p-value >0.05).

Conclusion: The absorbance and transmittance values of all the three indigenous aligners did not change significantly after invivo aging at most of the evaluated wavelengths.


Absorbance, Orthodontic aligners, Polyethylene terephthalate glycol, Polyurethane, Spectrophotometry, Transmittance

Clear aligner therapy is an orthodontic treatment modality in which the patient wears a series of customised removable aligners that gradually moves the teeth to a desired position (1),(2). In the past few decades, there has been a substantial increase in the number of patients seeking clear aligner treatment because of its aesthetic superiority over labial orthodontics and improved comfort than lingual orthodontics (1),(2),(3),(4). Even though, labial and lingual orthodontic appliances provide better biomechanical advantage than clear aligners there has been an increasing trend in the practice of clear aligners across the globe as patients prefer the invisibility it provides (2),(5).

Clear aligners offer several advantages including reduced incidence of white spot lesions, caries, gingivitis or periodontal disease compared to patients undergoing fixed orthodontic and are less cumbersome to the orthodontist with substantial reduction in chair side time and total number of visits (5),(6).

The concept of using transparent tooth positioner was pioneered by Kesling HD, followed by clear retainers by Pontiz RJ, vacuum formed dental contour appliance by Nahoum HI and the Essix retainers by Sheridan J (5),(7),(8),(9). In 1997 Align Technology introduced Invisalign and since then it dominated the world market of clear aligners for two decades and was holding more than 40 patents (10),(11). The patents expired in October 2017. This marked a sudden influx of aligner companies across the globe including India (11).

The absorbance and the transmittance value of the clear aligners is mainly determined by the chemical composition of the materials used in the manufacturing of the aligner (12),(13),(14). From an aesthetic point of view, the colour stability and transparency of orthodontic clear aligners are expected to be stable throughout the treatment (15). The initial aligners systems used single layer of rigid polyurethane sheets for fabrication of clear aligners. Later Polyvinyl Chloride (PVC), Polyethylene Terephthalate Glycol (PET-G) and elastomer reinforced materials with superior aesthetic and mechanical properties were introduced (16),(17),(18),(19),(20),(21),(22),(23). Each manufacturer use one of these materials for the fabrication of clear aligners but the specific composition is mostly kept as a trade secret, hence the optical and mechanical properties of a clear aligner cannot be concluded based on the generic material used (12),(13),(14),(15),(16),(17),(18),(19),(20),(21),(22),(23).

The mechanical properties of various clear aligners have been widely investigated with in-vitro and clinical studies (18),(20),(24),(25),(26). Though, studies evaluating the optical properties of clear aligners are there in the literature, the studies were done only under laboratory conditions where exact oral environment including masticatory stress, varying oral temperature and pH could not be simulated and there are no published studies on the indigenous aligners manufactured in India (7),(13),(14),(16),(25).

Considering this lacunae in the existing literature the current study was designed to evaluate and compare the absorbance, transmittance and staining of three indigenous clear aligners; Clearbite aligners (JJ Orthodontics Pvt. Ltd, Thrissur, Kerala), Dentcare clear aligners (DentCare Dental Lab Pvt. Ltd. Ernakulum, Kerala), and Smile aligners, (smile aligners Inc. Mumbai, Maharashtra) after in-vivo aging. The result of this study will help us to determine the aesthetic stability of the three indigenous aligners and also it will help us to understand if these values of clear aligner is a prerequisite for the clear aligner selection.

Material and Methods

A prospective clinical study was conducted in the Department of Orthodontics and Dentofacial Orthopaedics, SRM Dental College, Chennai, Tamil Nadu, India, from August to December 2021. This study was approved by Institutional Review Board and Institutional Ethical Committee (SRMDC/IRB/2019/MDS/No.107). This clinical study is registered in clinical trial registry of India with a registration number CTRI/2021/08/035866.

Sample size calculation: The sample size was calculated using G Power software. The estimated sample size with power of 85% and α error of 0.05% was 36 with 12 in each group. The data for sample size determination was obtained from the study published by Lombardo L et al., in 2015 (7). Convenience sampling technique was used, 36 volunteers who fulfilled the inclusion criteria and gave informed consent to participate in the study were selected.

Inclusion criteria: Subjects falling in the age group of 18-28 years with Decayed, Missing and Filled Teeth (DMFT) score not more than 2, plaque index not more than 2, without previous history of orthodontic treatment or bruxism were included in the study. The 36 volunteers were divided into three groups of 12 each in order of their enrollment.

Group A (n=12): Subjects received aligners from Clearbite (JJ Orthodontics Pvt.Ltd, Thrissur, Kerala).

Group B (n=12): Subjects received aligners from Dentcare (Dent Care Dental Lab Pvt.Ltd. Ernakulam, Kerala).

Group C (n=12): Subjects received aligners from Smile aligners (smile aligners Inc. Mumbai, Maharashtra).

Study Procedure

The maxillary impression of the 36 subjects belonging to three study groups were obtained with polyvinyl siloxane material and sent to the respective laboratories for the fabrication of clear aligners. Two sets of aligners with a thickness of 0.8 mm were fabricated from each impression for the clinical study (Table/Fig 1).

One set of aligners from each group were sent to the laboratory for measurement of absorbance and transmittance before in-vivo aging. The next set of aligners were delivered to the study subjects and were instructed to wear the aligners for 24 hours for 14 days except while brushing and eating and to clean the aligner with soft texture tooth brush under running water once in the morning and once at night. The aligners were retrieved at the end of 14 days and transported to the lab for measurement of absorbance and transmittance after in-vivo aging.

The absorbance and transmittance were measured using a Shimadzu UV-3600i Plus UV-Vis-NIR spectrophotometer (Table/Fig 2). The aligners were sectioned from canine to canine to remove the lingual portion by using a rotating saw before spectrophotometer analysis to expose the labial wall. The aligners were mounted on the holder and placed inside the spectrophotometer for the measurement (Table/Fig 3). The absorbance and transmittance was measured in the wavelength of 400-700 nm, within the visible spectrum of light at intervals of 20 nm.

Statistical Analysis

Descriptive and Inferential statistics were analysed using Statistical Package for Social Sciences (SPSS) (IBM Corp. Released 2011. IBM SPSS Statistics for Windows Version 20.0. Armonk, NY:IBM Corp). Paired t-test was done for intra group readings and Oneway Analysis of Variance (ANOVA) was used to compare the values among the groups.


In all the three groups of aligners evaluated an increase in the absorbance value was noted at all the wavelengths after in-vivo aging in patient’s mouth for 14 days but the increase was not statistically significant (p-value >0.05) [Table/Fig-4-6]. The lowest absorbance value of 0.8873±0.006 was recorded in the group C samples at the wavelength of 420 nm and the highest of 1.000±0.000 was recorded in group B samples at 440 nm before aging. But one-way ANOVA comparing the mean absorbance of the samples belonging to the three experimental groups at all wavelengths measured before In-vivo aging showed no significant difference between the values obtained (Table/Fig 7).

The lowest absorbance value of 1.0270±.235 was recorded in the group B samples at the wavelength of 660 nm and the highest of 1.85±0.543 was recorded in group C samples at 440 nm after aging. But an one-way ANOVA comparing the mean absorbance of the group A, B and C samples after in-vivo aging showed no significant difference between the values obtained at all wavelengths (Table/Fig 8).

Transmittance values of group A samples reduced after 14 days of intraoral use but the difference was not statistically significant (Table/Fig 9). The transmittance values of group B reduced significantly between 400- 440 nm above which the reduction was not significant (Table/Fig 10). In group C, the reduction was significant only at wavelengths between 400-460 nm and 680-700 nm (Table/Fig 11). The lowest transmittance value of 8.7627±0.032 was recorded in the group A samples at the wavelength of 620 nm and the highest of 11.9787±1.64587 was recorded in group C samples at 420 nm before aging.

The lowest transmittance value of 5.2017±1.56050 was recorded in the group B samples at the wavelength of 420 nm and the highest of 9.5747±5.23260 was recorded in group A samples at 420 nm after aging. The mean transmittance values of the samples from the group A, B and C before aging and after aging were compared using oneway ANOVA test. The comparison did not reveal a significant difference between the mean values at all wavelengths (Table/Fig 12),(Table/Fig 13).


The current study demonstrated no significant difference in the optical properties of the three aligners evaluated before and after in-vivo aging for 14 days as measured by absorbance and transmittance values. They exhibited similar optical properties after in-vivo aging though there was a trend of increased absorbance and reduced transmittance noted in all the three aligners.

The properties of the aligners are hugely dependent on the chemical composition, thickness of the material used and the manufacturing process (7),(12),(15). Amorphous polymers like polyurethane, PET-G, polyvinylchloride and polysulfone exhibit high translucency and preferred as aligner materials over crystalline polymers which are highly opaque and unaesthetic (12),(15),(24),(26),(27). All the aligners are not created equal, and those currently on the market differ in terms of their material, thickness and manufacturing process. Alexandropoulos A et al., evaluated the chemical and mechanical properties of three contemporary thermoplastic orthodontic materials (polyurethane, polyester and polyethylene glycol terephthalate) and observed significant differences in their chemical structure and mechanical properties and therefore anticipated differences in their clinical behaviour (28).

Ideal mechanical properties and chemical stability is a basic requisite of clear aligners. The transparency of the aligner is the major key to their success and popularity (1),(2),(7),(12),(13),(14),(16),(17),(18). Studies evaluating the optical properties of clear aligners are there in the literature but there are no published studies on the indigenous aligners manufactured in India (Table/Fig 14) (7),(13),(22),(25),(29).

Most aligner companies recommend a 14 days consecutive wear of appliance for a minimum of 22 hours per day. The transparency of rthodontic clear aligners should be stable during this period or else the aligners may become less aesthetically appealing during this time period which may be of a clinical concern [12,27]. Clear aligners are exposed to various masticatory stress, salivary enzymes, staining food and beverages, mouthwashes in the oral environment during their two weeks of continuous wear [11,13,22]. These variables are very difficult to simulate in an experimental setup and in-vitro protocols exaggerate the time of exposure of the aligners to the staining agents. Hence, in this study the optical properties of the aligners were evaluated after in-vivo aging for 14 days in patients mouth.

The absorbance and transmittance before and after in-vivo aging and in-vitro staining was measured using a Shimadzu 3600 plus UV-VIS-NIR spectrophotometer using the method recommended by Lombardo L et al., to expose the labial wall (7). Absorbance is defined as a measure of the capacity of a substance to absorb light of a specified wavelength. Transmittance is the fraction of incident light, at an established wavelength that passes through the material. Greater the transmittance, the more transparent the material and greater the absorbance value, less transparent the material (7).

The result of the current study is in contradiction with the previous study conducted by Lambardo L et al., Liu CL et al., and Bernard G et al., who absorbed significant differences in their optical properties and colour stability of different clear aligner brands (7),(25),(29). This may be due to the reason that these studies were conducted under in-vitro conditions where the aligners underwent prolonged exposure to the food stains which were greater than the average time to which the aligners are exposed to stains during intraoral use. Further, the aligners used in these studies differed in their chemical composition, thickness and the method of processing which may affect the optical properties to a great extent.

The clearbite aligners were made from Polyurethane and Polyethylene Terephthalate Glycol (PET-G) where Dentcare aligners and Smile aligners were fabricated from PET-G. Though, the composition of the aligner materials used to fabricate the three aligners evaluated in the current study differed slightly. The thickness of the material (0.8 mm) and processing methods (thermoforming) were essentially same (30),(31),(32).

Gracco A et al., investigated the optical properties of clear aligners before and after intraoral use and noted that the intraoral conditions influence the optical properties and chemical stability of the aligners. (22). A similar study conducted by Zafeiriadis AA et al., assessed the in-vivo colour alterations of two different clear retainers and observed that used retainers exhibited greater colour change and the colour change increased with time for both materials (13).

The fact that the current study did not demonstrate any such difference may be attributed to the huge improvement in the quality of materials available for aligner fabrication and better methods of aligner processing and finishing available in the current era.


This study did not include the dietary variables that affect the staining characteristics of the aligner material.


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DOI and Others

DOI: 10.7860/JCDR/2022/59186.17033

Date of Submission: Jul 21, 2022
Date of Peer Review: Aug 22, 2022
Date of Acceptance: Sep 06, 2022
Date of Publishing: Oct 01, 2022

• Financial or Other Competing Interests: None
• Was Ethics Committee Approval obtained for this study? Yes
• Was informed consent obtained from the subjects involved in the study? Yes
• For any images presented appropriate consent has been obtained from the subjects. No

• Plagiarism X-checker: Jul 27, 2022
• Manual Googling: Aug 25, 2022
• iThenticate Software: Aug 31, 2022 (9%)

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