Deep learning for temporomandibular joint arthropathies: A systematic review and meta-analysis.

BACKGROUND AND OBJECTIVE: The accurate diagnosis of temporomandibular disorders continues to be a challenge, despite the existence of internationally agreed-upon diagnostic criteria. The purpose of this study is to review applications of deep learning models in the diagnosis of temporomandibular joint arthropathies. MATERIALS AND METHODS: An electronic search was conducted on PubMed, Scopus, Embase, Google Scholar, IEEE, arXiv, and medRxiv up to June 2023. Studies that reported the efficacy (outcome) of prediction, object detection or classification of TMJ arthropathies by deep learning models (intervention) of human joint-based or arthrogenous TMDs (population) in comparison to reference standard (comparison) were included. To evaluate the risk of bias, included studies were critically analysed using the quality assessment of diagnostic accuracy studies (QUADAS-2). Diagnostic odds ratios (DOR) were calculated. Forrest plot and funnel plot were created using STATA 17 and MetaDiSc. RESULTS: Full text review was performed on 46 out of the 1056 identified studies and 21 studies met the eligibility criteria and were included in the systematic review. Four studies were graded as having a low risk of bias for all domains of QUADAS-2. The accuracy of all included studies ranged from 74% to 100%. Sensitivity ranged from 54% to 100%, specificity: 85%-100%, Dice coefficient: 85%-98%, and AUC: 77%-99%. The datasets were then pooled based on the sensitivity, specificity, and dataset size of seven studies that qualified for meta-analysis. The pooled sensitivity was 95% (85%-99%), specificity: 92% (86%-96%), and AUC: 97% (96%-98%). DORs were 232 (74-729). According to Deek's funnel plot and statistical evaluation (p =.49), publication bias was not present. CONCLUSION: Deep learning models can detect TMJ arthropathies high sensitivity and specificity. Clinicians, and especially those not specialized in orofacial pain, may benefit from this methodology for assessing TMD as it facilitates a rigorous and evidence-based framework, objective measurements, and advanced analysis techniques, ultimately enhancing diagnostic accuracy.

Comparing the accuracy of 3 different liquid crystal display printers for dental model printing.

INTRODUCTION: This study aimed to evaluate the accuracy in terms of trueness and precision of 3 different liquid crystal display (LCD) printers with different cost levels. METHODS: Three LCD 3-dimensional (3D) printers were categorized into tiers 1-3 on the basis of cost level. The printers' accuracies were assessed in terms of trueness and precision. For this research, 10 standard tessellation language (STL) reference files were used. For trueness, each STL file was printed once with each 3D printer. For precision, 1 randomly chosen STL file was printed 10 times with each 3D printer. After that, a model scanner was used to scan the models, and STL comparisons were performed using reverse engineering software. For the measurements regarding trueness and precision, the Friedman test was used. RESULTS: There were significant differences among the 3 printers (P <0.05). The trueness and precision error were lower in models printed with a tier-1 printer than in the remaining 3D printers (P <0.05). The tier-2 and -3 printers presented very similar performance. CONCLUSIONS: LCD 3D printers can be accurately used in orthodontics for model printing depending on the specific orthodontic use. The cost of a printer is relevant to the results only for the higher expense of the 3D printer in this study.

Comparing efficacy of the mandibular advancement device after drug-induced sleep endoscopy and continuous positive airway pressure in patients with obstructive sleep apnea.

PURPOSE: The purpose of this study was to compare objective and self-reported outcomes of two treatments for managing mild, moderate, and severe obstructive sleep apnea (OSA) in adults: a mandibular advancement device (MAD) and continuous positive airway pressure (CPAP). METHODS: Patients diagnosed with OSA by means of polysomnography (PSG) included one group treated with a custom-made, two-piece, adjustable MAD and a second group treated with CPAP for 8 weeks. Before the initiation of the treatment, all patients assigned to MAD underwent drug-induced sleep endoscopy (DISE), and all CPAP group patients underwent manual titration of CPAP after PSG. Objective (PSG) and self-reported (Epworth Sleepiness Scale [ESS] and Short Form Health Survey [SF-36]) data were used to assess outcomes. Collected data included apnea-hypopnea index (AHI), mean capillary oxygen saturation (SpO2), oxygen desaturation index (ODI), arousal index (AI), degree of daytime sleepiness, and quality of life. A PSG follow-up after 8 weeks with MAD in situ, and data from the CPAP data card were used to assess the effect of the two treatments. RESULTS: A total of 59 patients included 30 treated with MAD and 29 treated with CPAP. Between baseline and the 8-week follow-up, the mean AHI score decreased significantly from 35.1 to 6.8 episodes/h (p < 0.001) in patients treated with MAD and from 35.2 to 3.0 episodes/h (p < 0.001) in patients treated with CPAP. The mean AHI score at the 8-week follow-up was significantly lower in CPAP group than in MAD group (p = 0.003). The two groups did not differ significantly at follow-up regarding SpO2 (p = 0.571), ODI (p = 0.273), AI (p = 0.100), ESS score (p = 0.648), and SF-36 score (p = 0.237). CONCLUSION: In the short term, patients on CPAP attained better PSG outcomes in terms of AHI reduction. Both MAD after DISE evaluation and CPAP resulted in similar improvements in clinical symptoms and health-related quality of life, even in patients with severe OSA.

Outcome Predictors in Civilian and Iatrogenic Arterial Trauma.

BACKGROUND: Our aim was to identify predictors of mortality and limb loss in iatrogenic and civilian arterial trauma. METHODS: Cases were identified by searching prospectively maintained registries. Multivariable logistic regression was used to identify independent outcome predictors. RESULTS: During the study period, 285 patients with arterial trauma were managed with endovascular (n = 20) or open (n = 265) repair. Iatrogenic injuries increased in frequency during the course of the study, from 23.9% during the first decade to 35.9 and 55.7% during the second and third decade, respectively (p < 0.001). Endovascular management increased in frequency during the course of the study, from 0% during the first decade to 5.1 and 11.1% during the second and third decade, respectively (p = 0.005). Mortality was 9.8%, and limb loss (in cases with injury of the aorta or limb arteries, n = 259) was 6.2%. Independent predictors of mortality included increased age (odds ratio, 95% confidence interval [OR, 95% CI] 1.05 (1.02-1.07), p < 0.001), blunt trauma (OR [95% CI] 4.8 (1.9-12.2), p = 0.001) and the number of RBC units transfused intraoperatively (OR [95% CI] 1.25 (1.1-1.4), p = 0.001). Independent predictors of limb loss included the first half of the study period (OR [95% CI] 3.9 (1.1-14.1), p = 0.04), lower extremity arterial trauma (vs upper extremity, aortic, common or external iliac artery trauma, OR [95% CI] 8.3 (1.9-35.7), p = 0.004), bone fracture (OR [95% CI] 16.9 (4.7-62.5), p < 0.001) and the number of RBC units transfused intraoperatively (OR [95% CI] 1.16 (1.02-1.33), p = 0.024). CONCLUSION: Increasingly iatrogenic in cause and managed by endovascular methods, arterial trauma remains a problem associated with significant mortality and limb loss. Identification of unfavourable outcome predictors may help clinicians involved with arterial trauma to escalate the level of care.

Predictors of Operative Mortality of 928 Intact Aortoiliac Aneurysms.

BACKGROUND: The aim of this study is to identify preoperative and intraoperative factors associated with in-hospital mortality of intact abdominal aortoiliac aneurysm repair. METHODS: In this observational study, prospectively collected information included demographics, risk factors, comorbidities, aneurysm characteristics (including special aneurysm presentation, i.e., inflammatory, mycotic/infected, aortocaval fistula), investigations, and operative variables. Receiver operating characteristic) curve analysis of the Glasgow aneurysm score (GAS) and the Vascular Study Group of New England (VSGNE) score was performed in the subgroup of bland aneurysms undergoing isolated elective repair. RESULTS: A total of 928 cases with intact aortoiliac aneurysms had an elective (n = 882) or urgent (n = 46) repair, associated with an in-hospital mortality of 1.7% and 8.7%, respectively (P = 0.01). Open repair (n = 514) was a predictor of higher mortality (3.3% vs. 0.5% for endovascular aneurysm repair [EVAR], n = 414, odds ratio [OR] 7.1, P = 0.003), and so was the pre-EVAR era (4.8% vs. 1.3% in the EVAR era, OR 4.0, P = 0.004). Other significant predictors included the presence of abdominal/back pain (7.5% vs. 1.3%, OR = 6.0, P = 0.001), preoperative angiography (7% vs. 1.6%, OR = 4.5, P = 0.01), special aneurysm presentation (10.9% vs. 1.5%, OR = 8.1, P < 0.001), concomitant major procedures (19% vs. 1.7%, OR = 14.0, P < 0.001), serious intraoperative complications (9.1% vs. 1.5%, OR = 6.6, P = 0.001), median number of transfused units of blood intraoperatively (2 and 0 for cases with and without mortality, respectively, P < 0.001), and procedure duration (270 and 150 min for cases with and without mortality, respectively, P < 0.001). Open repair (OR = 4.5, P = 0.05), special aneurysm presentation (OR = 6.58, P = 0.001), and concomitant major procedures (OR = 14.3, P < 0.001) were independent predictors of higher mortality. ROC curve analysis for the GAS (P = 0.87) and VSGNE score (P = 0.10) failed to demonstrate statistical significance in the subgroup of bland aneurysms undergoing isolated elective repair. CONCLUSIONS: Our study has demonstrated independent risk factors for mortality, which should be considered when contemplating aortoiliac aneurysm repair. We failed to externally validate the GAS and VSGNE score.

Validation of the 3D SYM VEIN Symptom Assessment Tool.

OBJECTIVE: The aim was to validate the SYM VEIN consensus 3D scoring tool in chronic venous disease (CVD). METHODS: This was a prospective cohort study with a total of 35 consecutive patients with CVD. Patients with CVD undergoing saphenectomy were assessed with the revised Venous Clinical Severity Score (r-VCSS), the CIVIQ-20 quality of life score questionnaire, and the SYM VEIN consensus statement 3D system, pre-operatively and four weeks post-operatively. The total 3D score was tested for reliability, construct validity, and responsiveness. RESULTS: The total 3D score demonstrated good reliability and internal consistency (Cronbach's alpha 0.85). Principal component analysis identified three groups of symptoms (paraesthesia, burning pain, and pruritus, vs. heaviness, sensation of swelling and aching/pain, vs. restless leg and throbbing pain) demonstrating a high intragroup correlation and likely to share similar pathophysiology, indicative of adequate construct validity. The total 3D score showed a significant correlation with r-VCSS and CIVIQ-20 score (rho .46, p = .005 and rho .65, p < .001, respectively) indicative of adequate convergent validity. After saphenectomy, significant reductions (p < .001) of the total 3D, and 3D scores for all but two individual venous symptoms were observed, indicative of excellent responsiveness. Median total 3D score was reduced from 31 to 6 (83.8% decrease, p < .001), median r-VCSS was reduced from 6 to 0 (100% decrease, p < .001), and median CIVIQ-20 score was reduced from 24 to 14 (40% decrease, p < .001). The difference of median percentage change between r-VCSS and CIVIQ-20 score vs. total 3D score was significant (p = .005 and p < .001, respectively). CONCLUSION: The total SYM VEIN 3D score has good reliability, construct validity and excellent responsiveness, although less prone to change after saphenectomy compared with r-VCSS.

Improved effectiveness of the repositionable GORE EXCLUDER AAA endoprosthesis featuring the C3 delivery system compared with the original GORE EXCLUDER AAA endoprosthesis for within the instructions for use treatment of aortoiliac aneurysms.

OBJECTIVE: To compare two endograft types, the original GORE EXCLUDER AAA endoprosthesis (W. L. Gore & Associates, Flagstaff, Ariz) with the repositionable GORE EXCLUDER featuring the C3 delivery system, which allows repositioning of the proximal part of the graft to achieve accurate placement in relation to the renal arteries, in unselected patients with aortoiliac aneurysms. In a second nested, substudy we investigated the relative effect of the standard Gore and Gore Dryseal introducer sheaths on intraoperative transfusion needs. METHODS: We retrospectively analyzed prospectively collected information. The primary composite outcome measure was the intraoperative misdeployment or migration of the endograft's main body, proximally or distally to the renals (leading to technical failure or requiring either placement of aortic cuff extenders or conversion to open repair). Secondary outcome measures included the composite long-term event of rupture and/or type I/III endoleak. RESULTS: A total of 313 consecutive patients (303 males; median age, 73 years) had either an original GORE EXCLUDER device (n = 174) or the new device (n = 139) placed between 2004 and 2011 and 2011 and 2017, respectively, to treat an infrarenal aortoiliac aneurysm or an isolated common iliac artery aneurysm. The primary composite outcome measure occurred more often in patients who had the original GORE EXCLUDER device placed (10.9% vs 3.6% for the new device; odds ratio, 0.30; 95% confidence interval, 0.11-0.84; P = .016), confirmed by multivariate logistic regression analysis. This difference between the two groups was exclusively driven by distal misdeployment or migration of the endograft (10.3% vs 2.9% for the new device; P = .01), mostly requiring aortic extender placement. Intraoperative blood transfusion rates were lower in patients who had the GORE Dryseal introducer sheath used (1.1% vs 18.9% for the original GORE introducer sheath; OR, 0.05; 95% confidence interval, 0.006-0.35; P < .001). At a mean follow-up of 1.7 years (maximum, 13 years), 11 patients developed the composite event. On univariate Cox analysis, significant predictors included female gender (P = .003), absence of dyslipidemia (P = .023), the primary outcome measure (P = .006), and failure to cannulate (P = .009), but not device type or other variables. On multivariate Cox regression, female gender (hazard ratio, 37; P < .001), chronic obstructive pulmonary disease (hazard ratio, 3.99; P = .045), the primary outcome measure of the study (hazard ratio, 8.9; P = .002), and failure to cannulate (hazard ratio, 43; P = .003) were all independent predictors. CONCLUSIONS: Our study has demonstrated that the repositionable GORE EXCLUDER has important safety characteristics compared with the original device and equivalent long-term effectiveness. Additional benefit was obtained with the use of the Gore Dryseal introducer sheath.

Editor's Choice - A Systematic Review and Meta-Analysis of the Efficacy and Safety of Anticoagulation in the Treatment of Venous Thromboembolism in Patients with Cancer.

OBJECTIVE/BACKGROUND: The aim was to review the relative efficacy and safety of anticoagulation for managing venous thromboembolism (VTE) in patients with cancer. METHODS: A systematic review and meta-analysis was carried out. On 17 May 2018 the MEDLINE and Scopus databases were searched for randomised controlled trials (RCTs). Eligible RCTs had to be performed in patients with cancer exclusively or to report results on a subset of patients with cancer. The main study outcomes (efficacy/recurrent VTE and safety/bleeding events) were expressed as risk ratios (RR) with a 95% confidence interval (CI). The quality of evidence was assessed following the GRADE method. RESULTS: Twenty-three RCTs with 6980 patients were identified. Low molecular weight heparins (LMWHs) were more effective than vitamin K antagonists (VKAs) in preventing recurrent VTE (RR 0.58, 95% CI 0.45-0.75) and deep vein thrombosis (RR 0.44, 95% CI 0.29-0.69) but not pulmonary embolism (PE), bleeding, or overall mortality. Direct oral anticoagulants (DOACs) were more effective than VKAs in preventing recurrent VTE (RR 0.65, 95% CI 0.45-0.95) but not DVT, PE, overall mortality, or bleeding. However, anti-Xa DOACs were more effective (RR for VTE 0.64, 95% CI 0.42-0.97) and caused less bleeding than VKAs, although major bleeding was reduced only with DOACs not requiring initial parenteral anticoagulation (RR 0.45, 95% CI 0.21-0.97). In a direct comparison, DOACs were more effective than LMWHs in preventing VTE recurrence (RR 0.64, 95% CI 0.45-0.90) but caused more major bleeding (RR 1.75, 95% CI 1.10-2.77), with no difference in fatal bleeding and overall mortality. Quality of evidence, where sufficient, was mostly moderate or high. CONCLUSION: Compared with VKAs, LMWHs and DOACs are more effective in treating VTE, but the former caused less bleeding. DOACs are more effective than LMWHs in preventing VTE recurrence but may carry a higher risk of major bleeding, pending additional information by ongoing trials.

Absorbable sutures for the achievement of stable osteosynthesis in surgery for craniosynostosis.

AIM OF THE STUDY: The goal of the present study was to analyse the exclusive use of absorbable suture material (Vicryl) in the fixation of transposed bone segments in cranial vault reshaping without modification of the osteotomy design. CLINICAL RATIONALE FOR THE STUDY: In the surgical correction of craniosynostosis, bone fixation using osteosynthesis is a key step. Absorbable osteosynthesis is a widespread tool in cranial vault remodelling, but only a limited number of studies have described the use of absorbable sutures in the treatment of patients with craniosynostosis. MATERIALS AND METHODS: In 72 children with various types of craniosynostosis, up to 24 months of age, osteosynthesis was conducted exclusively with Vicryl sutures. All patients were evaluated for the stability of postoperative results, and foreign body reactions were examined as part of the routine clinical and radiological follow-up ranging from 1 to 36 months. RESULTS: All examined children exhibited stable postoperative conditions with immediate stability of all remodelled cranial vaults. 2D and 3D radiological examinations demonstrated good bony union in all cases. Significant foreign body reactions were not observed and bone healing was noted at all sites. CONCLUSION AND CLINICAL IMPLICATIONS: The exclusive application of absorbable suture material enables stable and cost-effective osteosynthesis in craniofacial surgery without altering the osteotomy design.

Acute Effects of Graduated Elastic Compression Stockings in Patients with Symptomatic Varicose Veins: A Randomised Double Blind Placebo Controlled Trial.

OBJECTIVES: To investigate the effectiveness of graduated elastic compression stockings (GECS) below the knee in improving symptoms in patients with varicose veins in the absence of high quality evidence. METHODS: This was a randomised double blind placebo controlled trial. Thirty patients with no experience of elastic stockings, presenting with primary varicose veins causing calf pain or aching were randomised to a GECS (18-21 mmHg at the ankle level, n=15) or a placebo stocking (0 mmHg, n=15). Pain or aching of the index leg after 1 week was the primary outcome measure. In patients with bilateral varicose veins the leg with the most severe pain/aching was considered. Other defined symptoms were secondary outcome measures. All symptoms were scored on a visual analogue scale (VAS). RESULTS: The two study groups were well balanced at baseline. At the completion of the study after 1 week, GECS were more effective than placebo stockings in reducing pain or aching (VAS score 1.7±3.0 vs. 4.5±2.8 for placebo, p=.02), while non-significant trends were observed for some of the remaining symptoms of the index leg, including feeling of swelling (VAS score 0.9±1.9 vs. 3.3±3.5 for placebo), paraesthesiae (VAS score 0.2±0.6 vs. 2.1±3.1 for placebo), and the number of symptoms other than pain or aching (1.3±1.1 vs. 2.8±1.7 for placebo). Number needed to treat (95% CI) for a 50% or complete improvement of pain or aching in the index leg was 2 (95% CI 1.2-5.5) and 2 (95% CI 1.2-5.3), respectively. Mean daily use of the placebo stockings and GECS was 8.0 hours and 10.2 hours, respectively (p=.13). CONCLUSIONS: Among patients with varicose veins, GECS seem effective in ameliorating symptoms, particularly pain or aching, compared with placebo stockings after 1 week of use. Long-term studies are justified.

Open versus closed surgical exposure of palatally impacted maxillary canines: comparison of the different treatment outcomes-a systematic review.

Objective: This study aims to compare the effectiveness of two different canine exposure techniques (open and closed) regarding periodontal outcomes, duration of surgical treatment and canine's eruption, patient's inconvenience, aesthetics, and orthodontic treatment complications. Search methods: Electronic database searches of published and unpublished literature were performed. The reference lists of eligible studies were hand searched for additional studies. Selection criteria: Randomized clinical trials (RCTs), quasi-randomized clinical trials (Q-RCTs) and non-randomized trials of prospective and retrospective design with patients of any age that compared group with palatally impacted canines treated by open exposure to a similar group treated by closed exposure technique were selected. There was not any restriction in language or year of publication. Data collection and analysis: Study selection, data extraction, and risk of bias assessment were performed individually and in duplicate. Results: Search strategy resulted in 159 articles and nine articles were selected for the final analysis. They were three non-randomized trials, one Q-RCT, and two reports of another Q-RCT and three reports of one RCT. The level of reported evidence was high for the RCT and one Q-RCT but poorer for the other trials. Four articles reported periodontal outcomes, three searched the duration of surgical procedure, two the duration of canine eruption, two investigated patient's inconvenience, two reported on failure rates and two addressed aesthetic outcomes. The results are inconsistent and there is considerable disagreement for the majority of the outcomes among studies. Conclusion: According to existing articles we may conclude that there is no difference between the two techniques regarding the periodontal outcomes and aesthetic appearance. The surgical procedure is shorter in the open exposure group and the amount of postoperative pain during the first day is similar between the open and closed surgical exposure patients. However, these conclusions are based on two single trials with high level of evidence, while the rest of the studies present high risk of bias.

Endarterectomy achieves lower stroke and death rates compared with stenting in patients with asymptomatic carotid stenosis.

BACKGROUND: It is currently unclear if carotid artery stenting (CAS) is as safe as carotid endarterectomy (CEA) for patients with significant asymptomatic stenosis. The aim of our study was to perform a systematic review and meta-analysis of trials comparing CAS with CEA. METHODS: On March 17, 2017, a search for randomized controlled trials was performed in MEDLINE and Scopus databases with no time limits. We performed meta-analyses with Peto odds ratios (ORs) and 95% confidence intervals (CIs). Quality of evidence was assessed with the Grading of Recommendations Assessment, Development, and Evaluation method. The primary safety and efficacy outcome measures were stroke or death rate at 30 days and ipsilateral stroke at 1 year (including ipsilateral stroke and death rate at 30 days), respectively. Perioperative stroke, ipsilateral stroke, myocardial infarction (MI), and cranial nerve injury (CNI) were all secondary outcome measures. RESULTS: The systematic review of the literature identified nine randomized controlled trials reporting on 3709 patients allocated into CEA (n = 1479) or CAS (n = 2230). Stroke or death rate at 30 days was significantly higher for CAS (64/2176 [2.94%]) compared with CEA (27/1431 [1.89%]; OR, 1.57; 95% CI, 1.01-2.44; P = .044), with low level of heterogeneity beyond chance (I2 = 0%). Also, stroke rate at 30 days was significantly higher for CAS (63/2176 [2.90%]) than for CEA (26/1431 [1.82%]; OR, 1.63; 95% CI, 1.04-2.54; P = .032; I2 = 0%). MI at 30 days was nonsignificantly lower for CAS (12/1815 [0.66%]) compared with CEA (16/1070 [1.50%]; OR, 0.53; 95% CI, 0.24-1.14; P = .105; I2 = 0%); however, CNI at 30 days was significantly lower for CAS (2/1794 [0.11%]) than for CEA (33/1061 [3.21%]; OR, 0.13; 95% CI, 0.07-0.26; P < .00001; I2 = 0%). Regarding the long-term outcome of stroke or death rate at 30 days plus ipsilateral stroke during follow-up, this was significantly higher for CAS (79/2173 [3.64%]) than for CEA (35/1430 [2.45%]; OR, 1.51; 95% CI, 1.02-2.24; P = .04; I2 = 0%). Quality of evidence for all stroke outcomes was graded moderate. CONCLUSIONS: Among patients with asymptomatic stenosis undergoing carotid intervention, there is moderate-quality evidence to suggest that CEA had significantly lower 30-day stroke and also stroke or death rates compared with CAS at the cost of higher CNI and nonsignificantly higher MI rates. The long-term efficacy of CEA in ipsilateral stroke prevention, taking into account perioperative stroke and death, was preserved during follow-up. There is an urgent need for high-quality research before a firm recommendation is made that CAS is inferior or not to CEA.

When static meets dynamic: Comparing cone-beam computed tomography and acoustic reflection for upper airway analysis.

INTRODUCTION: Upper airway measurement can be important for the diagnosis of breathing disorders. Acoustic reflection (AR) is an accepted tool for studying the airway. Our objective was to investigate the differences between cone-beam computed tomography (CBCT) and AR in calculating airway volumes and areas. METHODS: Subjects with prescribed CBCT images as part of their records were also asked to have AR performed. A total of 59 subjects (mean age, 15 ± 3.8 years) had their upper airway (5 areas) measured from CBCT images, acoustic rhinometry, and acoustic pharyngometry. Volumes and minimal cross-sectional areas were extracted and compared with software. RESULTS: Intraclass correlation on 20 randomly selected subjects, remeasured 2 weeks apart, showed high reliability (r >0.77). Means of total nasal volume were significantly different between the 2 methods (P = 0.035), but anterior nasal volume and minimal cross-sectional area showed no differences (P = 0.532 and P = 0.066, respectively). Pharyngeal volume showed significant differences (P = 0.01) with high correlation (r = 0.755), whereas pharyngeal minimal cross-sectional area showed no differences (P = 0.109). The pharyngeal volume difference may not be considered clinically significant, since it is 758 mm3 for measurements showing means of 11,000 ± 4000 mm3. CONCLUSIONS: CBCT is an accurate method for measuring anterior nasal volume, nasal minimal cross-sectional area, pharyngeal volume, and pharyngeal minimal cross-sectional area.

Comparing CBCT to model scanner for dental model scanning. An in vitro imaging accuracy study.

OBJECTIVE: The aim of this study is to compare the accuracy of cone beam computed tomography (CBCT) for dental model scanning to the accuracy of model scanners. METHODS: Subjects from private practice were collected and scanned according to specific selection criteria. A total of 10 STL files were produced and used as reference files. They were printed with a three-dimensional (3D) printer and then scanned with CBCT and model scanner. For trueness evaluation, all models were scanned once with both equipments. Each file derived from each scan was compared with the corresponding reference model file. For the precision measurements, the physical model from the first master reference model file was scanned 10 times with each equipment and compared with the reference STL file. A reverse engineering software was used for all 3D best-fit comparisons. RESULTS: With regard to the measurement of trueness of each method, the calculated mean root mean square (RMS) value was 0.06±0.01mm for the CBCT, and 0.15±0.02mm for the model scanner. There was a significant difference between the two methods (P<0.01). For the evaluation of precision of each scanner, the mean RMS value was 0.0056±0.001mm for the CBCT, and 0.153±0.002mm for model scanner. There was a significant difference between the two methods (P<0.01). CONCLUSIONS: Cone Beam Computed Tomography seems to be an accurate method for scanning dental models. CBCT performs better than model scanners to scan dental models in terms of trueness and precision.

Effect of printing technology and orientation on the accuracy of three-dimensional printed retainers.

OBJECTIVES: To evaluate the impact of printer technology and print orientation on the accuracy of directly printed retainers. MATERIALS AND METHODS: Digital retainers were printed with two different printing technologies: digital light processing (DLP) and stereolithography (SLA), using two different orientations: 0° and 90°. After printing, the retainers (n = 40) were scanned using cone-beam computed tomography. The DICOM files were then converted into standard tessellation language (STL) files. Comparison of the printed retainers with a master file was done by superimposition using a three-dimensional (3D) best-fit tool in Geomagic software. A ±0.25 mm tolerance was set to detect differences between the superimposed files. Statistical analysis was conducted (Kruskal-Wallis and Wilcoxon-Mann-Whitney tests, with Bonferroni correction). RESULTS: The lowest median average deviation was observed for the DLP horizontally printed models (median, [interquartile range (IQR)] = 0.01 mm, [-0.01, 0.02]) followed by the SLA horizontally printed retainers (median, [IQR] = 0.05 mm, [0.03, 0.07]). The highest median inside the tolerance levels ratio was observed for the horizontally SLA printed retainers (median, [IQR] = 78.9%, [74.4, 82.4%]) followed by the horizontally DLP printed retainers (median, [IQR] = 78.2%, [74.5, 80.7%]). CONCLUSIONS: Both technologies (DLP and SLA) showed 3D printed results compatible with orthodontic clinical needs. Printing orientation was more important than printer type regarding its accuracy. Additional studies are needed to evaluate the accuracy of direct printed appliances clinically.

Effect of printing technology, layer height, and orientation on assessment of 3D-printed models.

BACKGROUND: Three-dimensional (3D) printing technologies have become popular in orthodontics. The aim of this study is to determine the effect of printing technology, orientation, and layer height on the accuracy of 3D-printed dental models. METHODS: The maxillary arch of a post-treatment patient was scanned and printed at different orientations (0°, 90°) and layer thicknesses (25 µm, 50 µm, 100 µm, and 175 µm) using two different printing technologies (digital light processing and stereolithography). The 120 models were digitally scanned, and their average deviation from the initial model was analyzed using 3D algorithm. A multivariable linear regression analysis was used to estimate the effect of all variables on the average deviation from the initial model for the common layer thicknesses (50/100 µm). Finally, one-way ANOVA and Tukey posthoc test was used to compare the stereolithography (SLA) 25 µm and digital light processing (DLP) 175 µm groups with the groups that showed the least average deviation in the former analysis. RESULTS: The multivariable linear regression analysis showed that the DLP 50 µm (mean ± SD: -0.022 ± 0.012 mm) and 100 µm (mean ± SD: -0.02 ± 0.009 mm) horizontally printed models showed the least average deviation from the initial model. Finally, the DLP 175 µm horizontally printed models (mean ± SD: 0.015 ± 0.005 mm) and the SLA 25 µm horizontally (mean ± SD: 0.011 ± 0.005 mm) printed models were more accurate. CONCLUSIONS: All the models showed dimensional accuracy within the reported clinically acceptable limits. The highest accuracy was observed with DLP printer, 175 µm layer thickness, and horizontal orientation followed by SLA printer, 25 µm layer thickness, and horizontal orientation.