Evaluation of the effective dose of cone beam computed tomography and multi-slice computed tomography for temporomandibular joint examinations at optimized exposure levels.

OBJECTIVES: To compare the effective dose to patients from temporomandibular joint examinations using a dental cone-beam CT device and a multi-slice CT device, both before and after dose optimization. METHODS: A Promax3D (Planmeca, Helsinki, Finland) dental cone-beam CT and a Lightspeed VCT (GE, Fairfield, USA) multi-slice CT were used. Organ doses and effective doses were estimated from thermoluminescent dosimeters at 61 positions inside an anthropomorphic phantom at the exposure settings in clinical use. Optimized exposure protocols were obtained through an optimization study using a dry skull phantom, where four observers rated image quality taken at different exposure levels. The optimal exposure level was obtained when all included criteria were rated as acceptable or better by all observers. RESULTS: The effective dose from a bilateral examination was 184 µSv for Promax3D and 113 µSv for Lightspeed VCT before optimization. Post optimization the bilateral effective dose was 92 µSv for Promax3D and 124 µSv for Lightspeed VCT. CONCLUSIONS: At optimized exposure levels, the effective dose from cone-beam CT was comparable to MSCT.

Comparative analysis of upper airway volume with lateral cephalograms and cone-beam computed tomography.

INTRODUCTION: In this study, we aimed to evaluate the adenoidal nasopharyngeal ratio (ANR) on lateral cephalograms by assessing upper airway volumes using cone-beam computed tomography (CBCT) images as the validation method. METHODS: Fifty-five patients were included in the study, and it was essential that the lateral cephalograms and CBCT images taken at their examinations were not more than 1 week apart. There were 32 subjects in group A (age ≤15 years) and 23 subjects in group B (age >15 years). The ANR was measured on the lateral cephalograms. The area and volumetric measurements of the nasopharynx and the total upper airway were obtained from CBCT images. Repeated measurements of the ANR and airway volume were performed on 10 subjects by 2 observers. RESULTS: Group A had a higher correlation (r = -0.78) between the ANR and the nasopharynx volume than did group B (r = -0.57). The ANR had a weak correlation with the total upper airway volume (group A, r = -0.48; group B, r = -0.32). Both measurements made on lateral cephalograms and CBCT were highly reproducible in terms of intraobserver and interobserver agreement. CONCLUSIONS: Based on our results, the measurement of the ANR on lateral cephalograms can be used as an initial screening method to estimate the nasopharynx volumes of younger patients (age ≤15 years).

Comparison of Swedish and Norwegian Use of Cone-Beam Computed Tomography: a Questionnaire Study.

OBJECTIVES: Cone-beam computed tomography in dentistry can be used in some countries by other dentists than specialists in radiology. The frequency of buying cone-beam computed tomography to examine patients is rapidly growing, thus knowledge of how to use it is very important. The aim was to compare the outcome of an investigation on the use of cone-beam computed tomography in Sweden with a previous Norwegian study, regarding specifically technical aspects. MATERIAL AND METHODS: The questionnaire contained 45 questions, including 35 comparable questions to Norwegian clinics one year previous. Results were based on inter-comparison of the outcome from each of the two questionnaire studies. RESULTS: Responses rate was 71% in Sweden. There, most of cone-beam computed tomography (CBCT) examinations performed by dental nurses, while in Norway by specialists. More than two-thirds of the CBCT units had a scout image function, regularly used in both Sweden (79%) and Norway (75%). In Sweden 4% and in Norway 41% of the respondents did not wait for the report from the radiographic specialist before initiating treatment. CONCLUSIONS: The bilateral comparison showed an overall similarity between the two countries. The survey gave explicit and important knowledge of the need for education and training of the whole team, since radiation dose to the patient could vary a lot for the same kind of radiographic examination. It is essential to establish quality assurance protocols with defined responsibilities in the team in order to maintain high diagnostic accuracy for all examinations when using cone-beam computed tomography for patient examinations.

Accuracy of virtually planned and CAD/CAM-guided implant surgery on plastic models.

STATEMENT OF PROBLEM: Studies of guided implant surgery have identified various methods that could influence accuracy. The present investigation was designed to limit the factors contributing to accuracy and to compare the results for 5 different surgeons. PURPOSE: The purpose of this study was to evaluate any deviation between virtually planned and actually placed implants by 5 surgeons performing computer-aided design/computer-aided manufacturing (CAD/CAM)-guided implant surgery on duplicate plastic models. MATERIAL AND METHODS: Five surgeons participated in the study, and each received 5 plastic maxillary jaw models. Thus, 25 models were used for implant placement with CAD/CAM-fabricated surgical templates. Each model contained 6 implants; therefore, a total of 150 implants were placed. The virtually planned and actually placed implant positions were compared for the apex, hexagon, depth, and angle with 2 computed tomography scans that were matched with voxel-based registration software. In addition, any differences in the 4 parameters among the surgeons were statistically tested. The data were analyzed with the t test, ANOVA, and Scheffé test (α=.05). RESULTS: A statistically significant difference between the virtually planned and actually placed implant positions was observed for 3 of the 4 outcome variables (the apex, hexagon, and depth; P<.05). A statistically significant difference was also noted among all surgeons regarding the positions of the apex, depth, and angle. CONCLUSIONS: The results of this study provide a better understanding of the differences in accuracy between surgeons when using a CAD/CAM surgical technique. There was a significant difference between the virtually planned and actually placed implant positions and between the surgeons for some of the variable parameters analyzed. The null hypothesis was thus rejected.

Comparison of diagnostic performance on approximal caries detection among Swedish and Chinese senior dental students using analogue and digital radiographs.

UNLABELLED: The objective was to investigate diagnostic performance on approximal caries detection among Swedish and Chinese dental students using analogue and digital radiographs in vitro. Additionally, to compare the diagnostic accuracy of two image modalities for approximal caries detection. 46 extracted premolars and molars were mounted in blocks and exposed with two intra-oral systems, one CCD based digital radiographs and one with conventional films. 10 Swedish and 10 Chinese senior dental students diagnosed the approximal sites of the teeth exposed with the digital and analogue images. A 5 point diagnosis confidence scale was applied for caries registration for all the observers. Subsequently, the teeth were sectioned and histo-pathologically analyzed in order to obtain a gold standard. The data were analyzed in terms of receiver operating characteristic (ROC) curves for evaluation of diagnostic accuracy of the two radiographic methods and for the two groups of students for enamel and dentinal caries detection, respectively. The area under the ROC curve was significantly higher for dentinal caries detection compared with enamel caries detection for both Chinese and Swedish students and for both imaging modalities (p<0.001). The present results indicated that the students' ability for enamel caries detection on approximal surfaces was poor. Neither between the two student groups (p=0.15-0.64) nor between the two image modalities (p=0.34-0.91) a statistically significant difference in detecting approximal caries was found. CONCLUSIONS: The two different intra-oral x-ray systems were equally accurate. Chinese and Swedish students showed similar outcomes in their performance for approximal caries detection.

Inhibition of microsomal prostaglandin E synthase-1 by aminothiazoles decreases prostaglandin E2 synthesis in vitro and ameliorates experimental periodontitis in vivo.

The potent inflammatory mediator prostaglandin E2 (PGE2) is implicated in the pathogenesis of several chronic inflammatory conditions, including periodontitis. The inducible enzyme microsomal prostaglandin E synthase-1 (mPGES-1), catalyzing the terminal step of PGE2 biosynthesis, is an attractive target for selective PGE2 inhibition. To identify mPGES-1 inhibitors, we investigated the effect of aminothiazoles on inflammation-induced PGE2 synthesis in vitro, using human gingival fibroblasts stimulated with the cytokine IL-1ß and a cell-free mPGES-1 activity assay, as well as on inflammation-induced bone resorption in vivo, using ligature-induced experimental periodontitis in Sprague-Dawley rats. Aminothiazoles 4-([4-(2-naphthyl)-1,3-thiazol-2-yl]amino)phenol (TH-848) and 4-(3-fluoro-4-methoxyphenyl)-N-(4-phenoxyphenyl)-1,3-thiazol-2-amine (TH-644) reduced IL-1ß-induced PGE2 production in fibroblasts (IC50 1.1 and 1.5 µM, respectively) as well as recombinant mPGES-1 activity, without affecting activity or expression of the upstream enzyme cyclooxygenase-2. In ligature-induced experimental periodontitis, alveolar bone loss, assessed by X-ray imaging, was reduced by 46% by local treatment with TH-848, compared to vehicle, without any systemic effects on PGE2, 6-keto PGF1α, LTB4 or cytokine levels. In summary, these results demonstrate that the aminothiazoles represent novel mPGES-1 inhibitors for inhibition of PGE2 production and reduction of bone resorption in experimental periodontitis, and may be used as potential anti-inflammatory drugs for treatment of chronic inflammatory diseases, including periodontitis.

Accuracy of virtually planned and template guided implant surgery on edentate patients.

PURPOSE: Scientific evidence regarding the accuracy of implants placed into patients by the aid of a surgical template is limited. The objective of the present study was to verify if any variation exists between virtually planned implants' position using a computer, compared with the subsequently clinically placed implants with the aid of a surgical template in the mandible and the maxilla. MATERIAL AND METHODS: A total number of 25 edentate jaws were treated with the aid of a surgical template. In total, 139 implants were inserted. Fifty implants were inserted in the mandible and 89 in the maxilla. A voxel-based registration method was used to match two separate cone-beam computed tomography scans of the patients. The implant positions were calculated and compared between the planned implants and the implants' clinical position after more than 1 year after surgery. The results included the linear differences in distance at the level of the hex, the apex, and the depth. The angular differences were presented in degrees. RESULTS: Statistical results indicated some factors with significant deviations. The greatest errors were found when comparing between patients moving during the computed tomography scans and those that did not move. The results showed significant divergence at the level of the hex and apex of the implants. CONCLUSION: The hypothesis was rejected, as the statistical results indicated that there were significant differences between virtually planned implants' position and the final position of implants placed clinically.

Soft tissue conditions and marginal bone changes around immediately loaded implants inserted in edentate jaws following computer guided treatment planning and flapless surgery: a ≥1-year clinical follow-up study.

BACKGROUND: Evaluation of the clinical conditions following computer guided treatment planning and flapless surgery is still limited. OBJECTIVES: The objective was to evaluate the soft tissue conditions and marginal bone changes after 1 year of function around immediately loaded implants inserted in edentate jaws following computer guided treatment planning and flapless surgery. MATERIAL AND METHODS: Twenty-nine edentate jaws (19 maxillae, 10 mandibles) treated with 165 implants using the Teeth-in-an-Hour™ protocol were included. In these patients, peri-implant soft tissue conditions and radiographic marginal bone changes were evaluated after ≥1 year of functional loading (mean: 19 months). RESULTS: The mean probing depth at case level was 2.6 mm (SD: 0.6). Bleeding on probing was recorded as a mean of 81.9% (SD: 23.0). Plaque index showed a wide range of 0-100%. The mean marginal bone change of measured sites evaluated on intraoral radiographs was -1.2 mm (SD: 1.4). A marginal bone loss more than 1.5 mm or 2.0 mm was observed in 42% and 27% of the measured sites, respectively. A pressure-like-ulcer was found in 9 cases. Implants with marginal bone loss of >1.5 mm were more frequently observed in cases with an ulcer than cases where no ulcer was found. CONCLUSION: Although the mean marginal bone loss after function in the present study was within the range of other reports presenting mean bone loss data after immediate implant loading, our patients showed a wide range of bone loss with several sites, where the bone loss was greater than the commonly used successful level (>1.5 mm).

Virtually planned and template-guided implant surgery: an experimental model matching approach.

OBJECTIVES: The objective of this study was to assess positional deviations between the implant replicas in the pre-operative plaster model created from a computer-aided design/computer-aided manufacturing (CAD/CAM) surgical template and the implant replicas in the post-operative plaster model that was made from patients' impressions taken at ≥1-year follow-up. MATERIAL AND METHODS: One hundred and thirty-nine implants were inserted in 25 edentulous jaws using Nobel Guide(™). Plaster models containing the implant replicas, one created from the surgical template before surgery and the other created from patients' impressions at ≥1-year follow-up, were scanned using a measuring device. Implant positions were matched with the best-fit alignment. Deviation was calculated at the level of the hex and the apex. The results were compared with a computed tomography matching study. Data were analysed using the paired t-test (α=0.05). RESULTS: There were positional deviations of implant replicas between pre- and post-operative plaster models both at the hex and the apex. The geometric mean of the deviation at the apex was 0.59 mm in the maxilla and 0.4 mm in the mandible. At the hex, it was 0.59 mm in the maxilla and 0.39 mm in the mandible. CONCLUSIONS: Statistically significant differences were observed in positions between the implant replicas in the pre-operative plaster models created from a CAD/CAM surgical template and the implant replicas in the post-operative plaster models that were made from patients' impressions taken at ≥1-year follow-up. Due to the lack of reference objects in the pre- and post-operative working casts, additional refinements are required in order to validate the impression matching method and recommend the method to be used.

Temporomandibular joint bone tissue resorption in patients with early rheumatoid arthritis can be predicted by joint crepitus and plasma glutamate level.

The aim was to investigate whether bone tissue resorption in early RA is related to crepitus of the temporomandibular joint (TMJ) and systemic levels of inflammatory mediators and markers and sex steroid hormones. Twentynine women and 18 men with recently diagnosed RA were examined for TMJ bone erosions with computerized tomography and TMJ crepitus was assessed. Blood samples were analyzed for glutamate, 5-HT, TNF, IL-1beta, IL-6, VEGF, inflammatory markers, and estradiol, progesterone and testosterone. The TMJ erosion score was positively correlated to glutamate, and TMJ crepitus where crepitus, glutamate and ESR explained 40% of the variation in the bone erosion score. In the patients without crepitus, bone erosion score was positively correlated to glutamate, which was not the case in the patients with crepitus. In conclusion, the results of this study show that TMJ bone tissue resorption can be predicted by TMJ crepitus and glutamate in early RA.

Virtual variation simulation of CAD/CAM template-guided surgeries performed on human cadavers: Part II.

STATEMENT OF PROBLEM: CAD/CAM template-guided surgery has gained attention as a method of improving the predictability of dental implant placement. However, due to possible variations during the manufacturing process and in the robustness of the template design, a virtual prediction of the potential positioning of the implants is needed. PURPOSE: The purpose of this study was to perform virtual variation simulations on virtually planned implant placements and to compare them with corresponding results from actual surgeries performed on human cadavers in a previous study. MATERIAL AND METHODS: Seventeen computer-aided plans were used for virtual variation simulation of surgeries conducted on 17 human cadavers and 145 implants placed in the cadavers. For each surgery, 10,000 virtual surgeries were performed, resulting in 1,450,000 implant placements. The results from the virtual variation simulations were statistically compared with the results from the actual surgeries. The Mann-Whitney U test was used to compare the implant distributions (alpha=.05). RESULTS: In the maxillae, the difference between the simulated average mean of the mean and the compared surgical average of the median was 0.22 mm (apex) and -0.35 mm (hex), and for the mandible, the corresponding values were -0.19 mm (apex) and -0.69 mm (hex). The simulated average mean of the range compared to the mean range of the maximum deviation results from the surgeries of the maxillae was 2.96 mm (apex) and 0.44 mm (hex), and 2.3 mm (apex) and 0.26 mm (hex) for the mandible. The implant distributions between the simulations and the surgeries were significantly different at both the hex (P<.001) and apex (P<.001). CONCLUSIONS: The implant distributions were neither static nor normally distributed. Thus, within the limitations of this study, the definitive geometrical variations of the implants were not static, as they depend on the individual anatomy of the jaws and the ability to place the CAD/CAM-guided surgical template in the proper position.

Accuracy of CAD/CAM-guided surgical template implant surgery on human cadavers: Part I.

STATEMENT OF PROBLEM: An optimal method for approaching the clinical surgical situation, when using preoperatively, virtually planned implant positioning, is to transfer data to a CAD/CAM-guided surgical template with the definitive position of the implant placed after surgery. The accuracy of CAD/CAM-guided surgeries must be determined to provide safe treatment. PURPOSE: The purpose of this study was to compare the deviation between the position of virtually planned implants and the position of implants placed with a CAD/CAM-guided surgical template in the mandible and the maxilla in human cadavers. MATERIAL AND METHODS: Ten maxillae and 7 mandibles, from completely edentulous cadavers, were scanned with CT, and 145 implants (Brånemark RP Groovy) were planned with software and placed with the aid of a CAD/CAM-guided surgical template. The preoperative CT scan was matched with the postoperative CT scan using voxel-based registration. The positions of the virtually planned implants were compared with the actual positions of the implants. Data were analyzed with a t test (alpha=.05). RESULTS: The mean measurement differences between the computer-planned implants and implants placed after surgery for all implants placed were 1.25 mm (95% CI: 1.13-1.36) for the apex, 1.06 mm (95% CI: 0.97-1.16) for the hex, 0.28 mm (95% CI: 0.18-0.38) for the depth deviation, 2.64 degrees (95% CI: 2.41-2.87) for the angular deviation, and 0.71 mm (95% CI: 0.61-0.81 mm) for the translation deviation. CONCLUSIONS: The results demonstrated a statistically significant difference between mandibles and maxillae for the hex, apex, and depth measurements in the variation between the virtually planned implant positions and the positions of the implants placed after surgery with a CAD/CAM-guided surgical template.

Endogenous glutamate in association with inflammatory and hormonal factors modulates bone tissue resorption of the temporomandibular joint in patients with early rheumatoid arthritis.

PURPOSE: The aim of this study was to investigate the relation between plasma level of glutamate and extent of radiographic bone erosion of the temporomandibular joint (TMJ) in patients with early rheumatoid arthritis (RA) in relation to inflammatory disease activity as well as estradiol and testosterone. MATERIALS AND METHODS: A total of 47 patients (29 women and 18 men) of whom 24 were seropositive were included shortly after being diagnosed with RA. Radiographic signs of bone tissue resorption (erosions) in the TMJ were recorded by cone-beam CT images, and an erosion score (0 to 24) was calculated for each patient. Venous blood was analyzed for rheumatoid factor, C-reactive protein, erythrocyte sedimentation rate, leukocyte particle count, glutamate, estradiol, and testosterone. Nonparametric statistical methods were used in the analysis. RESULTS: Resorptive changes of the TMJ were found in a major part of the patients. There was a significant positive correlation between plasma level of glutamate and extension of radiographic erosions that was strongest in the patients with low levels of C-reactive protein, estradiol, or testosterone. By contrast, erosions were correlated with C-reactive protein in patients with high levels of estradiol. The highest levels of glutamate were found in patients with low levels of C-reactive protein and estradiol. CONCLUSIONS: This study shows that a majority of patients with early RA presents radiographic signs of bone tissue resorption of the TMJ and that circulating glutamate is associated with the extent of these changes. The relationship between glutamate and bone resorption seems to be influenced by systemic inflammatory activity as well as estradiol and testosterone levels.

Comparison of periodontal and socioeconomic status between subjects with type 2 diabetes mellitus and non-diabetic controls.

BACKGROUND: The association among periodontal conditions, socioeconomic status (SES), and diabetes has been reported. However, there is a lack of published data comparing periodontal conditions among individuals with poorly controlled type 2 diabetes mellitus (T2D). The aim of the present study was to compare the periodontal conditions and SES between subjects with T2D and non-diabetic controls. METHODS: A total of 75 (31 males and 44 females) individuals with T2D (62 poorly controlled and 13 well-controlled) and 99 non-diabetic patients (healthy controls; 51 males and 48 females) participated in the study. Plaque index (PI), bleeding on probing (BOP), and probing depth (PD) were investigated. Random blood glucose level was recorded. Premolar and molar marginal bone loss (MBL) was measured digitally on scanned orthopantomograms. RESULTS: Individuals with poorly controlled T2D had increased MBL in molars and maxillary premolars (P<0.05) compared to individuals with well-controlled T2D. PI, BOP, and PD of 4 to <6 mm were increased in individuals with poorly controlled T2D compared to those with well-controlled T2D (P<0.001). There was no difference between the diabetic groups when PD was >or=6 mm. Individuals with poorly controlled T2D had a lower SES compared to patients with well-controlled T2D (P<0.05). Illiteracy and the number of missing teeth were not different between the groups. CONCLUSIONS: Radiologic and clinical indicators of periodontal destruction were increased in individuals with poorly controlled T2D. Low SES aggravated the periodontal condition in individuals with T2D.