Optical Coherence Tomography : A new era in dentistry

Introduction: During the last 20 years, optical coherence tomography (OCT) has evolved into a powerful technique for imaging of transparent and translucent structures1. OCT is an attractive noninvasive, nontouch imaging technique for obtaining high-resolution images. The first application in the biomedical optics field was for the measurement of the eye length. Optical Coherence Tomography (OCT) is an optical imaging method with medium penetration and high resolution primarily used in medicine. It has the potential to create live cross-sectional images even of non-transparent tissue at depths of up to 3 millimeters at a resolution of little more than a micrometer2.


Review article Optical Coherence Tomography: A new era in dentistry
Gupta G 1 , Dhaded S 2 , BN Shalini 3

Introduction:
During the last 20 years, optical coherence tomography (OCT) has evolved into a powerful technique for imaging of transparent and translucent struc- OCT is useful widely in almost all the fields of dentistry as it is capable of imaging both the hard and soft tissues and also can be used both in vitro and in

Conclusion:
OCT represents a valuable method for investigation and assessment of the health status of soft oral tissues and of hard dental structures.OCT can be used for evaluation of dental treatments reducing their failure rate and saving time and resources, by eliminating incorrect restorations before their insertion in the oral cavity.

tures 1 .
OCT is an attractive noninvasive, nontouch imaging technique for obtaining high-resolution images.The first application in the biomedical optics field was for the measurement of the eye length.Optical Coherence Tomography (OCT) is an optical imaging method with medium penetration and high resolution primarily used in medicine.It has the potential to create live cross-sectional images even of non-transparent tissue at depths of up to 3 millimeters at a resolution of little more than a micrometer 2 .Principles: One of the light characteristics which is used in the OCT is the phenomenon of interference.Two electromagnetic waves can interfere, add up or subtract each other and create a new one.Interferences could be fully constructive interference or completely destructive, but are usually partially destructive or constructive.(Fig.a) The light source has low-coherence like an SLD.Light is driven through the fibre to the beam splitter which divide by two (50/50) the beam.The first 50% are driven in direction of the sample (sample arm) to be reflected or backscattered by the different sample's tissues.The second 50% go through the reference arm ended by a movable mirror.Both are reflected back to the detection arm which has a detector to convert light intensity into electrical current.That current is converted to a digital signal and analyzed by a computer which generates an image of the sample 3 .(Fig.b) Uses In Dentistry:
vivo.The various applications are:A) To detect the presence or absence of material defects and microleakage at the prosthetic interfaces 4 .The investigations upon fixed partial prosthesis presented many defects that can lead to their deterioration.These defects are usually located inside the material and cannot be depicted visually or by other conventional imagistic method.B) OCT imaging offers the exciting potential to detect periimplantitis before significant osseous destruction occurs.OCT images of soft tissue surrounding failing implants are characterized by linear signal deficits, low-intensity collagen signals, and

Table 1 :Applications of OCT level
that are digitally recorded.These images pinpoint with great accuracy sites of disease progression.OCT also provides quantitative information regarding the thickness and character of the gingiva, root surface irregularities, and the distribution of subgingival calculus 2 .
G) Malignant lesions of oral mucosa: Accounting for 96% of all oral cancers, squamous cell carcinoma (SCC) is usually preceded by dysplasia presenting as white epithelial lesions on the oral mucosa (leucoplakia).This high-resolution optical technique permits minimally invasive imaging of near-surface abnormalities in complex tissues, having a penetration depth of 1-2 mm 8,9 .This permits in vivo noninvasive imaging of the macroscopic characteristics of epithelial and subepithelial structures, including: depth and thickness, histopathological appearance and peripheral margins.H) In the Todea C. et al. study 10 the quality of endodontic treatments and root canal fillings were investigated with eFOCT/CM technology.Areas