A comparison of perceived diagnostic image quality in direct digital panoramic images between standard and advanced external GOP image processing.

Objective: The objective of the present study was to study the effect of adaptive image processing (GOP processing) on the visibility of anatomical structures in direct digital panoramic images. Material and methods: The study comprised panoramic images of 50 consecutive adult individuals aged 18-60 years. Nine dentists working with dental radiology compared the structural image quality of all standard-processed and GOP-processed panoramic images for six anatomical structures, using a six-point scale for visual grading characteristics analysis. Results: For all anatomic structures a statistically significant difference in favour of the GOP was found. Conclusions: The present study shows that it is possible to improve perceived diagnostic image quality of direct digital panoramic radiography using GOP technology compared to the manufacturers' standard processing. Manufacturers' image-processing programs can be further developed, as there is a possibility of improving the perceived diagnostic content of an image with external processing.

Can adaptive post-processing of storage phosphor plate panoramic radiographs provide better image quality? A comparison of anatomical image quality of panoramic radiographs before and after adaptive processing.

OBJECTIVE: The objective of the present study was to study the effect of adaptive image processing on the visibility of anatomical structures in storage phosphor plate (SPP) panoramic images. MATERIALS AND METHODS: Three hundred SPP panoramic X-ray radiographs of children and adolescents were used. The radiographs were post-processed using general operator processor (GOP) technology, resulting in both a standard-processed and a GOP-processed radiograph. Four specialists in dental radiology compared the structural image quality of all standard-processed and GOP-processed panorama images for six anatomical structures, using a six-point scale for visual grading characteristics (VGC) analysis. RESULTS: For three of the anatomic structures - the root canal space of the mandibular left first premolar, mandibular canal left side and periodontal ligament space of the mandibular right first molar - there was a statistically significant difference to the GOP's advantage. For the three remaining structures - dentino-enamel junction of the maxillary right first molar, crista alveolaris of the mandibular left molar area and floor of maxillary sinus right side - no significant difference between standard processing and GOP processing was obtained. CONCLUSIONS: The study demonstrates that it is possible to improve the quality of SPP radiographs and the visibility of anatomical structures by using the GOP technique. Manufacturers' image-processing programs can be further developed, as there is a possibility of improving the diagnostic content of an image with external processing.

Dentists' use of digital radiographic techniques: Part II - extraoral radiography: a questionnaire study of Swedish dentists.

OBJECTIVE: The present study aims to gain knowledge about the dentist's use and choice of digital extraoral imaging methods, panoramic radiography and cone beam computed tomography (CBCT). MATERIALS AND METHODS: A questionnaire sent to 2481 dentists within the Swedish Dental Society contained questions about the panoramic technique and CBCT technique used, education, clinic size and type of service. The response rate was 53%. RESULTS: The study showed that 61% of the Swedish dentists had access to panoramic techniques and that 84% used a direct digital sensor, while 6% used storage phosphor plate techniques. Around 8% of the Swedish dentists had access to CBCT. It was also observed that group practices had two times higher odds of having panoramic equipment compared with solo practices. Approximately 40% of the dentists had undergone postgraduate education in oral radiology during the last 5 years. Dental nurses and dental hygienists exposed 92% of the panoramic radiographs and 75% of the CBCTs. Thirty per cent of those clinics with access to a panoramic unit exposed >30 panoramic radiographs per month and 56% of the clinics having access to CBCT did more than 75 examinations per year. CONCLUSIONS: Today 61% of Swedish dentists have access to panoramic radiography and 8% have access to CBCT. There is a greater likelihood of having access if the dentist works in the public dental health service or in a group practice and if the dentist has undergone any postgraduate course in oral radiology.

Surgical treatment of peri-implantitis using enamel matrix derivative, an RCT: 3- and 5-year follow-up.

OBJECTIVE: To assess the clinical and radiographic outcomes 3 and 5 years after the surgical treatment of peri-implantitis per se or in combination with an enamel matrix derivative (EMD). MATERIALS AND METHODS: At baseline, 29 patients were randomized to surgical treatment with adjunctive EMD or no EMD. One year after the surgical treatment of peri-implantitis, 25 patients remained eligible for survival analyses at the 3- and 5-year follow-up. The primary outcomes were implant loss and bone level (BL) change measured on radiographs, and the secondary outcomes, bleeding on probing, pus and plaque at each implant were analysed in 18 and 14 patients at the 3- and 5-year follow-up, respectively. RESULTS: After exclusion of four patients who discontinued the study, at the 3-year follow-up, 13 (100%) implants survived in the EMD group, and 10 of 12 (83%) in the non-EMD group. At the 5-year follow-up, 11 of 13 (85%) implants in the EMD group and nine of 12 (75%) in the non-EMD group survived. In multivariate modelling, BL changes and EMD treatment were positively associated with implant survival. Similarly, the same trend was seen in univariate analysis. CONCLUSIONS: An exploratory analysis suggests that adjunctive EMD is positively associated with implant survival up to 5 years, but larger studies are needed.

Dentists' use of digital radiographic techniques: Part I - intraoral X-ray: a questionnaire study of Swedish dentists.

OBJECTIVE: The present study aims to gain knowledge about the dentist's use and choice of digital intraoral imaging methods. MATERIALS AND METHODS: A questionnaire sent to 2481 dentists within the Swedish Dental Society contained questions about the type of X-ray technique used, problems experienced with digital radiography, and reasons for choosing digital technology, and about indications, clinic size and type of service. Response rate was 53%. RESULTS: Ninety-eight percent of the dentists had made the transition to digital radiography; only 2% used film technique, and solid-state detector (SSD) was the most used digital technique. More years in service decreases the likelihood of applying individual indications for performing a full mouth examination. More retakes were done with SSDs compared to storage phosphor plates. Reasons for choosing digital techniques were that work was easier and communication with the patients improved. However, dentists also experienced problems with digital techniques, such as exposure and projection errors and inadequate image quality. The Swedish Radiation Safety Authority states that all radiological examinations should be justified, something not always followed. CONCLUSIONS: This study showed that 98% of the respondents, Swedish dentists within the Swedish Dental Society, used digital techniques, and the most used was the solid-state technique.

Effectiveness of enamel matrix derivative on the clinical and microbiological outcomes following surgical regenerative treatment of peri-implantitis. A randomized controlled trial.

OBJECTIVE: This randomized clinical trial aimed at comparing radiological, clinical and microbial effects of surgical treatment of peri-implantitis alone or in combination with enamel matrix derivative (EMD). METHODS: Twenty-six subjects were treated with open flap debridement and decontamination of the implant surfaces with gauze and saline preceding adjunctive EMD or no EMD. Bone level (BL) change was primary outcome and secondary outcomes were changes in pocket depth (PD), plaque, pus, bleeding and the microbiota of the peri-implant biofilm analyzed by the Human Oral Microbe Identification Microarray over a time period of 12 months. RESULTS: In multivariate modelling, increased marginal BL at implant site was significantly associated with EMD, the number of osseous walls in the peri-implant bone defect and a Gram+/aerobic microbial flora, whereas reduced BL was associated with a Gram-/anaerobic microbial flora and presence of bleeding and pus, with a cross-validated predictive capacity (Q(2) ) of 36.4%. Similar, but statistically non-significant, trends were seen for BL, PD, plaque, pus and bleeding in univariate analysis. CONCLUSION: Adjunctive EMD to surgical treatment of peri-implantitis was associated with prevalence of Gram+/aerobic bacteria during the follow-up period and increased marginal BL 12 months after treatment.

The effect of anatomical noise on perception of low contrast in intra-oral radiographs: an in vitro study.

OBJECTIVES: Radiographic images suffer from varying amounts of noise. The most studied and discussed of these is random noise. However, recent research has shown that the projected anatomy contributes substantially to noise, especially when detecting low-contrast objects in the images. Our aim, therefore, was to evaluate the extent to which overprojected anatomical noise affects the detection of low-contrast objects in intra-oral images. METHODS: Our study used four common sensor models. With each sensor, we took four series of images, three series with and one series without an anatomical phantom present. In each series, we exposed a low-contrast phantom at 18 different exposure times using a standardized method. 4 observers evaluated all 288 images. RESULTS: The low-contrast characteristics differed substantially when imaging low contrast on a homogeneous background compared with imaging low contrast when an anatomical phantom was present. For three of the sensors, optimal exposure times for low-contrast imaging were found, while the fourth sensor displayed a completely different behaviour. CONCLUSIONS: Calibrating the low-contrast properties of an imaging system using low-contrast objects on a homogeneous background is not recommended. On an anatomical background, low-contrast properties are completely different, and these will mimic the clinical situation much more closely, directing the operator how to best use the system. There is a clear demand for further research on this subject.

Optimization of exposure in panoramic radiography while maintaining image quality using adaptive filtering.

Objective The purpose of the present study was to investigate the potential of using advanced external adaptive image processing for maintaining image quality while reducing exposure in dental panoramic storage phosphor plate (SPP) radiography. Materials and methods Thirty-seven SPP radiographs of a skull phantom were acquired using a Scanora panoramic X-ray machine with various tube load, tube voltage, SPP sensitivity and filtration settings. The radiographs were processed using General Operator Processor (GOP) technology. Fifteen dentists, all within the dental radiology field, compared the structural image quality of each radiograph with a reference image on a 5-point rating scale in a visual grading characteristics (VGC) study. The reference image was acquired with the acquisition parameters commonly used in daily operation (70 kVp, 150 mAs and sensitivity class 200) and processed using the standard process parameters supplied by the modality vendor. Results All GOP-processed images with similar (or higher) dose as the reference image resulted in higher image quality than the reference. All GOP-processed images with similar image quality as the reference image were acquired at a lower dose than the reference. This indicates that the external image processing improved the image quality compared with the standard processing. Regarding acquisition parameters, no strong dependency of the image quality on the radiation quality was seen and the image quality was mainly affected by the dose. Conclusions The present study indicates that advanced external adaptive image processing may be beneficial in panoramic radiography for increasing the image quality of SPP radiographs or for reducing the exposure while maintaining image quality.

Reduction of absorbed doses to the thyroid gland in orthodontic treatment planning by reducing the area of irradiation.

The objectives were to study whether a smaller area of irradiation resulted in a significant reduction in the dose of absorbed radiation to the thyroid gland for three radiographic modalities commonly used in cephalometric treatment planning. The aim of this research, was to study the effect of the field size on the absorbed dose of radiation to the thyroid gland, as measured with thermoluminescent dosimeters (TLD) in a phantom. Three radiographic modalities were used: panoramic, cephalometric, and intra-oral. For each modality, a large and a small collimator were used. A Rando Alderson phantom comprising a natural human cranium and cervical vertebrae embedded in a thermoplastic material simulating human soft tissue was used to measure absorbed dose to the thyroid gland. These measurements were made using lithium fluoride (LiF) TLDs. A significant reduction in absorbed dose to the thyroid gland was obtained by reducing the collimator in all three modalities. A 15% reduction in absorbed dose to the thyroid gland was achieved for the combination of small field sizes compared to the combination of large field sizes. Combining the use of selection criteria together with a smaller field of irradiation than normally used made a reduction in absorbed dose to the thyroid gland of around 30% possible.

Validation of measurements of mandibular protrusion in the treatment of obstructive sleep apnoea and snoring with a mandibular protruding device.

The aims of this study were to compare the maximum range of protrusion determined with a ruler with measurements made using a George Gauge (GG) and to validate the methods of measurement (ruler and GG) of the advancement established by mandibular protruding devices (MPDs), using cephalograms as the gold standard. The study comprised 77 patients (63 males, 14 females, mean age 54 years, range 31-73 years) with obstructive sleep apnoea (OSA) (n = 50) or complaints of snoring (n = 27). After a medical examination that included an overnight somnographic registration and a dental and stomatognathic examination, each patient was given a MPD. Measurements of the maximum range of protrusion with the GG and a ruler were compared. Pairs of upright cephalograms were taken with and without the MPD. The position of the mandible on the cephalograms was compared with ruler measurements of the device-induced protrusion in the incisor and premolar regions, the vertical opening in the anterior region, and GG construction bite registration. The maximum range of protrusion was significantly greater with GG than ruler measurements, on average +1.2 mm (P < 0.001). The mandibular position as measured in the incisor or premolar region with a ruler or on the cephalogram was not significantly different. GG values, however, were higher and differed significantly from ruler and cephalometric measurements (P < 0.001). The degree of anterior mandibular advancement with a MPD measured with a ruler in the incisor or premolar regions compared well with corresponding cephalometric measurements. The ruler and cephalometric measurements of the vertical opening with the MPD coincided well in the incisor region. The GG overestimated the maximum range of protrusion compared with ruler measurements.

Influence of mandibular protruding device on airway passages and dentofacial characteristics in obstructive sleep apnea and snoring.

The aim of the study was to evaluate the influence of a mandibular protruding device (MPD) after 2 years of nocturnal use on the upper airway and its surrounding structures. Lateral cephalograms in the upright position were taken of patients with obstructive sleep apnea (OSA) and of patients with snoring problems at the beginning of treatment and at the 2-year follow-up. Two computer programs were used to analyze the cephalograms. A total of 65 patients, 44 with OSA and 21 snorers, were analyzed. The linear distances in the pharynx had increased significantly at the 2-year follow-up; the calculated pharyngeal area had increased on average by 9% (mean, +58.3 mm(2)). The velum area had decreased (mean, -31.5 mm(2)), which accounts for about half the increase in the relative area of the pharynx. The average linear distances between the hyoid bone and the 2 reference lines, ie, nasal line (NL) and mandibular line (ML), had increased significantly. Mandibular protrusion (SNB) was slightly reduced, on average -0.4 degrees (P <.01), and the lower incisors were proclined (ILi/ML), on average +1.5 degrees (P <.05). In conclusion, nocturnal use of an MPD for 2 years increased the airway passage because of an increase in the relative area of the pharynx by a mean of 9% in OSA patients and snorers. A mandibular posterior rotation and a proclination of the lower incisors were observed but considered modest.

The effect of posture and a mandibular protruding device on pharyngeal dimensions: a cephalometric study.

The objectives were to evaluate the impact of body posture on cephalometric measures and the level and the extent to which treatment with a mandibular protruding device (MPD) affects pharyngeal width. The study was composed of 77 patients: 50 were diagnosed with obstructive sleep apnea (OSA) and 27 snored. After each patient underwent a baseline medical (including a somnographic registration), dental and stomatognathic examination, an MPD that would protrude the mandible 75% of the maximal protrusion range was fabricated. In a radiographic examination, four cephalograms were taken: two in the upright position with and without the MPD and two in the supine position with and without the MPD. The cephalometric measures focused on the pharyngeal structures. MPD treatment significantly increased the relative pharyngeal area (at the level of the oropharynx and the hypopharynx) by a mean of +89.6 mm2 (P < 0.01) in the upright posture. The relative pharyngeal area, however, was reduced by more than 50% in the supine position compared with the upright position, independent of MPD treatment. In the supine position, compared with upright, most pharyngeal measures decreased significantly; the hyoid was significantly lower and displaced posteriorly, and the area of the velum increased by a mean of +201.2 mm2 (P < 0.001). We conclude that the MPD significantly increased most pharyngeal measures except the linear distance between the hyoid bone and the third vertebra and decreased the area of the velum.