The minimum attributes for displaying intraoral radiographic digital images under the DICOM standard

Objectives

The purpose of this study was to determine the minimum attributes for display of intraoral (IO) radiographic digital images, on the basis of results of a survey completed by the Japanese Society for Oral and Maxillofacial Radiology (JSOMR). These attributes could then be used to develop proposals for the DICOM Standards Committee.

Methods

In December 2010, the JSOMR Task Group carried out a survey on display mapping and viewing solutions for IO images in university dental hospitals in Japan. The survey showed that a finite number of templates were in use at Japanese university dental hospitals. However, these templates were too complex for proposals to DICOM, and we thus believed that further simplification of the layout format was necessary to improve operating system efficiency, data transferability, and patient welfare. The JSOMR survey found that eight types of layout format were used at university dental hospitals across Japan; using these data as a starting point, we tested whether reducing the number of formats to three patterns was a viable option.

Results

During the reduction of the number of formats, we determined the following discrete imaging attributes: examination classification; image aspect; image size; image location; and projection style. Furthermore, for foreign countries, two patterns, 18 and 22, were added to image location for further clarity.

Conclusions

Five attributes are necessary for an effective new layout of IO images using a reference system.     

Use and implication of the DICOM standard in dentistry

DICOM is an international imaging standard that was developed for medicine and has been extended to support dentistry among other professions. This standard can provide the basis of interoperability for digital system outputs, providing image portability and reducing the danger of obsolescence rendering valuable diagnostic information impossible to display. This paper presents a brief overview of the origins and components of the DICOM standard and reports an ongoing initiative to promote interoperability within the DICOM as the industry standard for digital imaging in dentistry.     

Development and in vitro evaluation of an intra-oral controlled-release delivery system for chlorhexidine

Copolymers of hydroxyethyl methacrylate (HEMA) and methyl methacrylate (MMA) were prepared and used to fabricate a membrane-controlled reservoir-type controlled-release delivery system for chlorhexidine that should be suitable for intra-oral use. The reservoir of the system was prepared by softening an 80:20 mixture of chlorhexidine diacetate and 50:50 HEMA:MMA copolymer with methyl ethyl ketone (MEK), and pressing standard amounts of the resulting dough-like mixture into silicone rubber molds. A membrane was applied to the reservoirs by rotating them through a solution of 30:70 HEMA:MMA copolymer in MEK. The finished oval-shaped controlled-release pellets were approximately 4.7 mm wide, 3.3 mm high, and 7.4 mm long, and contained 45.0 +/- 3.7 mg of chlorhexidine diacetate. The mean in vitro release rate of chlorhexidine diacetate from the pellets into 37 degrees C water was 608 +/- 55 micrograms/24 h for days 2 through 11, and 389 +/- 50 micrograms/24 h for days 15 to 30 of the test period. The chlorhexidine released on day 30 was biologically active, as determined by a serial dilution assay against Streptococcus mutans. The extended release of biologically active chlorhexidine at a controlled rate from this system suggests that it is worthy of further evaluation for the intra-oral therapy of chlorhexidine-treatable oral infections in non-compliant and physically or mentally compromised individuals.     

Film-holding, beam-aiming and collimating devices as an aid to standardization in intra-oral radiography: a review

Comparison of serial films can provide the practitioner with invaluable information, allowing an assessment of the progression or arrest of approximal carious lesions, and of the level of alveolar bone. Meaningful comparisons are difficult however, if different angles and distances in relation to the film, object and focus are used for each exposure; the standardization of these variables by the use of film-holding and beam-aiming devices is therefore advantageous. The evolution of the various designs is reviewed. The development of the separate elements of the devices is considered: film holders, bite blocks, beam-aiming attachments, and additional collimators. These instruments have been used for many applications ranging from routine radiography to clinical research, and differ markedly in their complexity and practicability.The use of film-holding beam-aiming devices provides greater reproducibility in serial examinations, and allows the collection of valuable longitudinal information regarding caries and periodontal disease. In addition, such devices allow a reduction in the dose of radiation received by the patient, an improvement in image quality, and a more efficient technique. Therefore, their use is strongly advocated.     

A digital SLR or intra-oral camera: preference for acquisition within an image analysis system for measurement of disclosed dental plaque area within clinical trials

Objectives:  The aim of this investigation was to compare the accuracy and reproducibility of images acquired from two types of camera (digital SLR camera, Kodak DCS410, KJP, UK and an intra-oral camera, Schick Technologies, UK) for application within an imaging system used for the quantification of disclosed dental plaque.
Methods:  Subjects refrained from brushing their teeth for 24 h. Their teeth were then disclosed with Erythrosin FDC Red 3 and duplicate sets of images were obtained by each examiner of the upper central and lateral incisors. Images were then saved and measured for dental plaque area. These data were used to calculate reliability.
Results:  No statistically significant bias in the measurements of plaque area was found. The reliability results showed the method was reliable. However, the image analysis system incorporating the 35 mm SRL camera was more reliable for both operators, as demonstrated by their intra-operator results. This was also collaborated by the inter-operator results.
Conclusion:  In this investigation the digital SLR camera combined with the image analysis system and frame permitted greater reliability of dental plaque surface area measurements than the digital intra-oral camera. This conclusion was derived both from the reliability data and from the perceived ease of use and flexibility of both camera types. When combined with the use of the custom-made frame, the images using the digital SLR camera were highly reproducible, confirming the systems application within clinical trials.     

Integration of the digital imaging and communications in medicine standard into an oral and maxillofacial image management and communication system

OBJECTIVE: The purpose of this study was to provide developmental information about digital imaging and communications in medicine (DICOM) support applications for an image management and communication system (IMACS). STUDY DESIGN: An oral and maxillofacial radiology IMACS that uses a proprietary image format was implemented in March 1997 in a general hospital dental clinic that supports more than 100 cubicles. DICOM was implemented into this system in 1998. RESULTS: In March 1997, the clinic directly began processing oral and maxillofacial radiographs with digital image acquisition devices or converted them into proprietary digital format with a film digitizer. The digital images could then be viewed at workstations in the 11 different divisions of the department. A DICOM module was implemented to convert proprietary images into DICOM in June 1998. After the release of DICOM Supplement 32 on a digital x-ray, DICOM was implemented into the oral and maxillofacial radiology IMACS with a DICOM server and browser in June 1999. We describe the steps we took to implement this system in our institution with a brief report on the evaluation of this system. CONCLUSION: We implemented a DICOM oral and maxillofacial IMACS that complies with the American College of Radiology and the National Electrical Manufacturers Association Standard DICOM, version 3.0. Most DICOM service classes and roles are supported.     

The establishment of a diagnostic reference level for intra-oral dental radiography in Co. Wicklow

The use of diagnostic reference levels (DRLs) is part of the optimisation process of radiation protection, in that it identifies practices that are in need of corrective action, resulting in dose reduction. Their use is provided for in Irish and European legislation. In this project, measurements were carried out at 42 of the 46 licensed intra-oral xray machines in Co. Wicklow using an Unfors Mult-0-Meter. The third quartile patient entrance dose for a maxillary molar was calculated at 2.31 mGy, and all the measurements were below the European DRL of 4 mGy. The effect of digital radiography was analysed. There is always scope for the optimisation of patient dose. To facilitate this, a DRL of 2.5 mGy (patient entrance dose) is suggested for Ireland.     

Comparison of intra-oral long-cone paralleling radiographic surveys and orthopantomographs with special reference to the bone height

A comparison between bone height scores from long-cone paralleling radiographic surveys and orthopantomographs (Panex-EC) of forty-one patients was made. Intra-examiner reliability and inter-examiner objectivity of the measuring method (Schei ruler) proved to be very good (r = 0.954 and r = 0.923 respectively for the intra-oral surveys; r = 0.928 and r = 0.916 respectively for the orthopantomographs). Distribution and frequency of the non-measurable surfaces were evaluated. In each technique an attempt was made to discern the main cause of non-measurability: overlapping of adjacent structures, absence of the surface and absence of the apical region on the image. For twenty of the thirty-six surfaces significant differences were found between bone height scores for corresponding surfaces in the long-cone survey and in the orthopantomograph. In periodontal, prosthetic and conservative dentistry the long-cone paralleling technique should be considered as the best radiographic technique.     

Comparison of visual shade determination and an intra-oral dental colourimeter

The choice of correct tooth shade for the fabrication of a restoration remains a challenge, even for experienced clinicians. The aim of this research was to evaluate and compare the precision of two different shade determination methods in terms of repeatability. Maxillary right central incisor of 10 patients was evaluated visually with the use of Vitapan Classical shade guide by five observers and instrumentally with the Vitapan classical shade guide values of ShadeEye NCC intra-oral colourimeter three times consecutively. The in vivo repeatability of methods were analysed with the spectrophotometric L*, a*, b* values of the shade guide (Vitapan Classical). Within the limitations of this study, the repeatability of instrumental (intra-oral dental colourimeter) and visual shade determinations were acceptable.     

Occlusal adjustment under the control of intra-oral recording with the aid of the functiograph

Objective diagnosis of occlusal relationships is possible with the aid of a new instrument called the 'Functiograph'. It enables recordings of both the free and tooth-guided mandibular movements to be made intra-orally on the same tracing plate. A series of twenty cases has been undertaken and a number of selected examples are illustrated. Occlusal equilibration under the control of tooth-guided movement records enables the estimation of the results of occlusal correction in an objective and methodical way.     

A comprehensive in vitro study of image accuracy and quality for periodontal diagnosis. Part 2: The influence of intra-oral image receptor on periodontal measurements

The aim of the study was to determine the image receptors' influence on exposure levels, image accuracy, and quality for periodontal diagnosis. Periodontal defects from cadaver specimens were imaged using two intra-oral conventional films (E-, F/E-speed), four indirect receptors (Digora 8 bit, Vistascan 12 bit with/without filter, Vistascan 16 bit), and two solid-state sensors (Sigma 12 bit, VistaRay 14 bit) at rising exposure (20–160 ms). Three observers assessed the standardized radiographs for alveolar bone measurements (1,732, 31 sites) and for subjective rating of lamina dura, contrast, trabecularization, crater, and furcation involvements. The measurements were compared to the gold standard. For the imaging plates, highest measurement accuracy was found with Vistascan 16 bit (100% within 0.5 mm) and for solid-state sensors with VistaRay 14 bit (100%, 0.5 mm), although the latter are mostly not significantly different. Higher contrast resolution imaging plates require up to 50% less exposure time, but for solid-state sensors, the dose remains unchanged. For the latter, a higher bit depth does seem to provide more accurate depiction of the alveolar crest, counteracting blooming artifacts. The use of a dedicated periodontal filter contributes to higher accuracy at all exposure times (p < 0.05–0.0001). Accuracy of periodontal diagnosis increases with higher contrast resolution. Digital exposure levels are thus dependent of image receptor as well as X-ray generator.     

牙齿磨损非接触式三维图象检测系统的研制和检测

目的研制并检测用于牙齿磨损测量的非接触式三维图象检测系统。方法通过数据轮量化手控移动平台使被测模型在水平方向移动,由线状光条和一个面阵CCD(Charge Coupled Device)摄像机获得单个牙齿咬合面3000～4000个点的三维坐标(在0.5mm移动步长条件下)。在Windows环境下完成图象采集、图象显示和相关测量。结果该系统测量范围为15mm×15mm×15mm,测量的精确度达到0.01mm,平均测量误差小于0.01mm,具有良好的操作稳定性。用本系统与万能工具显微镜对一组有微小高度变化的标准块进行测量,二者间差异无显著性(P<0.05)。结论该系统具有较高的精确度,其非接触方式、良好的稳定性、简单快捷的操作优于传统测量方法。     

Selection of Streptococcus mutans and lactobacilli in an intra-oral human caries model

Microbiologic changes during caries development underneath a plaque-retaining band were investigated by the use of selective media for streptococci, Streptococcus mutans, and lactobacilli. The final four-week plaque samples on 16 experimental teeth in six young subjects were assessed. Seven experimental teeth in three other subjects were sampled at baseline and after one, two, and four weeks. All 23 experimental teeth developed a white spot lesion. In the final four-week plaque samples on the lesions, S. mutans accounted for 8% and lactobacilli 0.1% of the total CFU, both being significantly higher than in plaque from unbanded control surfaces. All experimental teeth sampled during lesion formation showed consistently elevated plaque levels of S. mutans and lactobacilli in comparison with baseline and control values at weeks one, two, and four. The results demonstrated a cariogenic environment in the human mouth associated with rapid selection of aciduric bacterial species such as S. mutans and lactobacilli.     

Peri-implant bone tissue assessment by comparing the outcome of intra-oral radiograph and cone beam computed tomography analyses to the histological standard

Objectives: The present study aims to identify radiographic methods revealing data that are most representative for the true peri‐implant bone as assessed by histology. Materials and methods: Eighty implants were placed in 10 minipigs. To assess matching between different image modalities, measurements conducted on intra‐oral digital radiographs (IO), cone beam computer tomography (CBCT) and histological images were correlated using Spearman's correlation. Paired tests (Wilcoxon test) were used to determine changes in the bone parameters after 2 and 3 months of healing. Results: Significant correlations between bone defect depth on IO and histological slices (r=+0.7, P<0.01), as well as on CBCT images and histological slices (r=+0.61, P<0.01), were found. CBCT and IO images deviate, respectively, 1.20 and 1.17 mm from the histology regarding bone defects. No significant correlations were detected between fractal analysis on CBCT, intra‐oral radiography and histology. For bone density assessment, significant but weaker correlations (r=+0.5, P<0.01) were found for intra‐oral radiography vs. histology. Significant marginal bone‐level changes could be observed after 3 months of healing using intra‐oral radiography. Conclusions: This study allowed linking radiographic bone defect depth to the histological observations of the peri‐implant bone. Minute bone changes during a short‐term period can be followed up using digital intra‐oral radiography. Radiographic fractal analysis did not seem to match histological fractal analysis. CBCT was not found to be reliable for bone density measures, but might hold potential with regard to the structural analysis of the trabecular bone. To cite this article:
Corpas LS, Jacobs R, Quirynen M, Huang Y, Naert I, Duyck J. Peri‐implant bone tissue assessment by comparing the outcome of intra‐oral radiograph and cone beam computed tomography analyses to the histological standard
Clin. Oral Impl. Res. 22 , 2011; 492–499
doi: 10.1111/j.1600‐0501.2010.02029.x     

The use of an intra-oral injection of ketorolac in the treatment of irreversible pulpitis

AIM: To examine whether an intra-oral injection of a nonsteroidal anti-inflammatory drug (ketorolac), in association with conventional local anaesthetic techniques, would improve the pulp extirpation rate in teeth with irreversible pulpitis. METHODOLOGY: A two group double-blind clinical trial was undertaken in the Dental Casualty Department of the University of Manchester School of Dentistry. Patients were randomly allocated to either the test or control group. The test group received an intra-oral injection of ketorolac (30 mg in 1 mL) in the buccal sulcus adjacent to the tooth being treated. After an interval of 15 min, they then received 2.2 mL of 2% lidocaine with 1 : 80 000 epinephrine by buccal infiltration in the maxilla or by inferior dental block in the mandible. The control group received an intra-oral injection of normal saline (1 mL) in the buccal sulcus adjacent to the tooth being treated, followed by the same local anaesthetic regime as the test group after the 15 min interval. Fifteen minutes after the local anaesthetic injections, pulp extirpation was attempted. All patients completed the short-form McGill pain questionnaire prior to treatment and completed identical questionnaires at 6 and 24 h after treatment. RESULTS: The study protocol set the number of patients to be treated at twenty. However, as the study progressed it became apparent that the intra-oral injection of ketorolac caused significant pain to four of the five patients who received it; therefore the study was terminated after ten patients had been treated. The results from the patients treated showed no significant difference in the pulp extirpation rate between the test and control groups. However, patients with higher pain scores at baseline were less likely to have the pulp completely extirpated, irrespective of whether they were in the test or control group. Pain scores for all patients decreased significantly from baseline to 24 h. CONCLUSION: An intra-oral injection of ketorolac did not improve the pulp extirpation rate in a small group of patients with irreversible pulpitis compared with a placebo. In addition, it was associated with such significant pain on injection that it cannot be recommended as a treatment in this situation.     

The measurement threshold and limitations of an intra-oral scanner on polished human enamel

ObjectiveTo investigate the measurement threshold of an intra-oral scanner (IOS) on polished human enamel.MethodsThe optical performance of an IOS was compared to a gold-standard non contacting laser profilometer (NCLP), on a painted microscope slide, compared to increasing particle size of silicon-carbide papers (21.8–269.0 μm) and separately on polished human enamel with increasing step-heights. The enamel samples were randomised (n = 80) and scanned using the IOS and NCLP at increasing step-height depths (μm) (1.87–86.46 μm) and quantified according to ISO:5436-1. The measurement threshold of the IOS was determined using a custom designed automated lesion localisation algorithm, corroborated by Gaussian skewness (Ssk) and kurtosis (Sku) analysis, to assess the minimum step-height measured on each enamel sample.ResultsThe NCLP showed statistically increased Sq surface roughness for all silicon carbide particle sizes compared to the microscope slide, whereas, the IOS Sq roughness discriminated silicon-carbide particles above 68.0 μm compared to the glass slide (p ≤ 0.02). On polished enamel, the automated minimum detectable step-height measurable on each sample was 44 μm. No statistically significantly different step-height enamel lesion measurements were observed between NCLP and IOS above this threshold (p > 0.05).SignificanceThis study revealed the fundamental optical metrological parameters for the IOS, was step-heights above 44 μm and this reflects the data acquisition of the system. These results highlight the limitations of IOS used in this study, mandating further research to optimise the performance of other IOS systems, for measuring wear of materials or tooth wear on human unpolished natural enamel surfaces.