• Current Optics and Photonics
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• 제7권3호
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• pp.283-296
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• 2023

An intraoral spectral domain optical coherence tomography (SD-OCT) system has been developed, using a custom-built hand-held scanner and spectrometer. The hand-held OCT probe, based on a microelectromechanical systems scanner and a self-built miniaturized drive circuit, had a field of view sufficient for dental diagnosis. The spectrometer using a fabricated f-theta lens provided the image depth required for dental diagnosis. The axial and transverse resolutions of the OCT system in air were 7.5 ㎛ and 12 ㎛ respectively. The hand-held probe could scan an area of 10 × 10 mm², and the spectrometer could image along a depth of 2.5 mm. To verify the utility of the developed OCT system, OCT images of tooth hard and soft tissues were acquired, and a user-interface program for diagnosis was developed. Early caries and microcracks that were difficult to diagnose with existing methods could be found, and the state of restoration could be observed. Measuring the depth of the gingival sulcus, distinguishing subgingival calculus, and detecting an implant under the gingiva suggested the possibility of the SD-OCT system as a diagnostic for dental soft tissues. Through the presented OCT images, the capability of the developed SD-OCT system for dental diagnosis was demonstrated.

• Imaging Science in Dentistry
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• 제46권3호
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• pp.173-178
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• 2016

Purpose: Optical coherence tomography (OCT) has been investigated as a novel diagnostic imaging tool. The utilisation of this equipment has been evaluated through several studies in the field of dentistry. The aim of this preliminary study was to determine through basic experiments the effectiveness of OCT in implant dentistry. Materials and Methods: To assess detection ability, we captured OCT images of implants in each of the following situations: (1) implants covered with mucosae of various thicknesses that were harvested from the mandibles of pigs; (2) implants installed in the mandibles of pigs; and (3) implants with abutments and crowns fixed with temporary cement. The OCT images were captured before cementation, after cementation, and after removing the excess submucosal cement. Results: If the thickness of the mucosa covering the implant body was less than 1 mm, the images of the implants were clearly detected by OCT. In the implants were installed in pigs' mandibles, it was difficult to capture clear images of the implant and alveolar bone in most of the samples. Remnants of excess cement around the implants were visible in most samples that had a mucosa thickness of less than 3 mm. Conclusion: Currently, OCT imaging of implants is limited. Cement remnants at the submucosal area can be detected in some cases, which can be helpful in preventing peri-implant diseases. Still, though there are some restrictions to its application, OCT could have potential as an effective diagnostic instrument in the field of implant dentistry as well.

• 치위생과학회지
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• 제16권4호
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• pp.257-262
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• 2016

TMR은 초기우식 평가의 gold standard로 여겨지나 시편을 파괴하여야만 시편의 무기질 밀도를 확인할 수 있는 실험법이다. 그러나 OCT는 비파괴적인 검사법으로 임상에서도 초기우식을 확인하는 데 사용하므로 본 연구에서는 $200{\mu}m$ 이상의 깊은 법랑질 초기우식에서의 OCT와 TMR에서 구한 integrated mineral loss값 간의 상관성을 확인하고자 하였다. $200{\mu}m$ 이상의 깊이를 갖는 인공 초기우식병소를 제작하여 TMR (${\Delta}Z_{TMR}$)과 OCT (${\Delta}R_{OCT}$)에서 구한 integrated mineral loss를 각각 구하여 상관성 분석을 시행하였으며 Bland-Altman plot을 그려 두 값 간의 오차 분석을 시행하였다. ${\Delta}R_{OCT}$과 ${\Delta}Z_{TMR}$ 간에는 유의한 상관성이 확인되었으며(r=0.491, p=0.003), Bland-Altman plot 상에서도 ${\Delta}Z_{TMR}$과 ${\Delta}R_{OCT}$값 간의 차이가 거의 대부분 오차 구간 내에 있는 것이 확인되어 두 측정 방법 간의 오차가 적은 것으로 확인되었다. 따라서 치과임상에서 OCT를 활용하면 초기우식병소의 탐지 및 모니터링 그리고 초기우식병소의 심도 파악이 가능할 것으로 여겨진다.

• 대한치과보철학회지
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• 제55권1호
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• pp.100-110
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• 2017

목적: 본 논문은 다양한 의료분야 진단에 사용되고 있는 비침습적 영상진단장치 중 낮은 투과 깊이를 가지지만 우수한 분해능과 실시간 영상획득이 가능한 광간섭 단층영상기기(OCT)의 기본 작동 원리, 종류, 장단점 및 응용분야 등을 소개한다. 재료 및 방법: 본 논문에 사용된 연구 데이터는 PubMed, 의료저널 및 관련논문을 검색하여 작성하였다. 결과: OCT를 이용하여 비치습적인 방법으로 실시간 영상 획득 및 고해상도의 생물학적 미세구조 관찰이 가능하며 이는 치아균열, 치아우식, 치아의 마모, 치주질환, 구강암, 그리고 수복물의 미세누출 평가 등에 유용하다. 결론: 현재 다양한 치의학적 진단에 OCT가 사용되고 있으며, 특히 치과보철학 분야에 있어서 지르코니아와 같은 재료의 발전과 함께 더욱 활용범위가 넓어질 것으로 판단된다.

• 한국콘텐츠학회논문지
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• 제12권8호
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• pp.240-247
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• 2012

보철물이 구강 내 제 기능을 하기 위해 가장 중요한 요소 중 하나는 적합도이다. 본 연구의 목적은 그 동안 시도되지 않았던 광간섭단층영상기를 이용하여 비파괴적인 방법으로 적합도를 측정해보고, 측정된 값을 기존의 방법으로 측정된 값과 비교하여 보고자 한다. 실험을 위해 상악 우측 중절치가 지대치인 석고모형 10개를 제작하고 치과용 캐드캠으로 각각의 모형에 해당하는 지르코니아 코어를 10개 제작하였다. 시편 당 5부위 씩 광간섭단층영상기로 적합도를 측정하고, 같은 부위를 기존의 방법인 실리 복제본 기술로 측정하였다. 두 집단 간의 평균 값에 유의한 차이가 있는지 알아보기 위해 독립표본 t-검정을 실시하였다(${\alpha}$=0.05). 그 결과 측정된 두 집단 간의 평균 값에는 유의한 차이를 보이지 않았고(P>0.05), 이러한 결과로 미루어 볼 때 앞으로 광간섭단층영상기를 이용한 보철물의 적합도 측정이 가능할 것으로 사료된다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2004년도 춘계종합학술대회
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• pp.140-143
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• 2004

본 논문은 치아 OCT영상에 웨이블릿 계수를 적용하여 영상을 향상한 연구이다. 처리 과정은 치아 OCT영상을 전처리하여 그래이 영상으로 만들고 웨이블릿 변환하여 상세계수들을 획득한 후 상세계수들로부터 고주파 성분을 추출하고 입력영상에 적용시켜 에지를 강조한다. 실험 결과 치아 OCT영상의 명암 대비가 강화되었으며, 화질이 개선되었다.

• Journal of Periodontal and Implant Science
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• 제47권1호
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• pp.30-40
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• 2017

Purpose: Optical coherence tomography (OCT) is a noninvasive diagnostic technique that may be useful for both qualitative and quantitative analyses of the periodontium. Micro-computed tomography (micro-CT) is another noninvasive imaging technique capable of providing submicron spatial resolution. The purpose of this study was to present periodontal images obtained using ex vivo dental OCT and to compare OCT images with micro-CT images and histologic sections. Methods: Images of ex vivo canine periodontal structures were obtained using OCT. Biologic depth measurements made using OCT were compared to measurements made on histologic sections prepared from the same sites. Visual comparisons were made among OCT, micro-CT, and histologic sections to evaluate whether anatomical details were accurately revealed by OCT. Results: The periodontal tissue contour, gingival sulcus, and the presence of supragingival and subgingival calculus could be visualized using OCT. OCT was able to depict the surface topography of the dentogingival complex with higher resolution than micro-CT, but the imaging depth was typically limited to 1.2-1.5 mm. Biologic depth measurements made using OCT were a mean of 0.51 mm shallower than the histologic measurements. Conclusions: Dental OCT as used in this study was able to generate high-resolution, cross-sectional images of the superficial portions of periodontal structures. Improvements in imaging depth and the development of an intraoral sensor are likely to make OCT a useful technique for periodontal applications.

• Journal of Periodontal and Implant Science
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• 제48권2호
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• pp.84-91
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• 2018

Purpose: The purpose of this study was to visualize and identify peri-implant bone defects in optical coherence tomography (OCT) images and to obtain quantitative measurements of the defect depth. Methods: Dehiscence defects were intentionally formed in porcine mandibles and implants were simultaneously placed without flap elevation. Only the threads of the fixture could be seen at the bone defect site in the OCT images, so the depth of the peri-implant bone defect could be measured through the length of the visible threads. To analyze the reliability of the OCT measurements, the flaps were elevated and the depth of the dehiscence defects was measured with a digital caliper. Results: The average defect depth measured by a digital caliper was $4.88{\pm}1.28mm$, and the corresponding OCT measurement was $5.11{\pm}1.33mm$. Very thin bone areas that were sufficiently transparent in the coronal portion were penetrated by the optical beam in OCT imaging and regarded as bone loss. The intraclass correlation coefficient between the 2 methods was high, with a 95% confidence interval (CI) close to 1. In the Bland-Altman analysis, most measured values were within the threshold of the 95% CI, suggesting close agreement of the OCT measurements with the caliper measurements. Conclusions: OCT images can be used to visualize the peri-implant bone level and to identify bone defects. The potential of quantitative non-invasive measurements of the amount of bone loss was also confirmed.

• 센서학회지
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• 제21권3호
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• pp.217-222
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• 2012

Optical coherence tomography(OCT) is a noninvasive optical imaging tool for biomedical applications. OCT can provide depth resolved two/three dimensional morphological images on biological samples. In this paper, we integrated an OCT system that was composed of an SLED(Superluminescent Light Emitting Diode, ${\lambda}_0$=1305 nm bandwith= 141 nm), a reference arm adopting a rapid scanning optical delay line(RSOD) to get high speed imaging, and a sample arm that used a micro electro mechanical systems(MEMS) scanning mirror. The sample arm contained a compact probe for imaging dental structures. The performance of the system was evaluated by imaging in-vivo human teeth with dental calculus, and the results indicated distinct appearance of dental calculus from enamel, gum or decayed teeth. The developed probe and system could successfully confirm the presence of dental calculus with a very high spatial resolution($6{\mu}m$).

• Journal of Periodontal and Implant Science
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• 제47권1호
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• pp.41-50
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• 2017

Purpose: The aims of the present study were to compare the image quality and visibility of tooth cracks between conventional methods and swept-source optical coherence tomography (SS-OCT) and to develop an automatic detection technique for tooth cracks by SS-OCT imaging. Methods: We evaluated SS-OCT with a near-infrared wavelength centered at 1,310 nm over a spectral bandwidth of 100 nm at a rate of 50 kHz as a new diagnostic tool for the detection of tooth cracks. The reliability of the SS-OCT images was verified by comparing the crack lines with those detected using conventional methods. After performing preprocessing of the obtained SS-OCT images to emphasize cracks, an algorithm was developed and verified to detect tooth cracks automatically. Results: The detection capability of SS-OCT was superior or comparable to that of trans-illumination, which did not discriminate among the cracks according to depth. Other conventional methods for the detection of tooth cracks did not sense initial cracks with a width of less than $100{\mu}m$. However, SS-OCT detected cracks of all sizes, ranging from craze lines to split teeth, and the crack lines were automatically detected in images using the Hough transform. Conclusions: We were able to distinguish structural cracks, craze lines, and split lines in tooth cracks using SS-OCT images, and to automatically detect the position of various cracks in the OCT images. Therefore, the detection capability of SS-OCT images provides a useful diagnostic tool for cracked tooth syndrome.