Impact of acquisition volume on cone beam computed tomography imaging of marginal bone: an ex vivo study.

OBJECTIVE: The current study explores whether there is a clinically relevant distinction in the measurement of marginal bone loss when comparing high-dose (HD) versus low-dose (LD) cone beam computed tomography (CBCT) protocols in small and large acquisition volumes.  Material and Methods: CBCTs of four human cadaveric preparates were taken in HD and LD mode in two different fields of view 8 × 8 cm2 (LV) and 5 × 5 cm2 (SV). In total, 43 sites of 15 teeth were randomly chosen, and marginal bone loss was measured twice in all protocols at 43 sites of 15 teeth by one calibrated investigator. Bland-Altman plots and Lin's concordance correlation coefficient (CCC) were calculated to assess the extent of agreement of the measurements. Additionally, the rater scored the certainty in each of the measurements. RESULTS: For HD-CBCT CCC of measurements obtained using SV versus LV was 0.991. CCC of measurements obtained using SV versus LV of LD-CBCT was 0.963. Both CCC values indicated excellent agreement between the two volumes in both protocols.  CCC also indicated high intramodality correlation between HD-CBCT and LD-CBCT independent of the acquisition volume (0.963 - 0.992). Bland-Altman plots also indicated no substantial differences. Results of certainty scoring showed significant differences (p = 0.004 (LV), p < 0.001(SV)) between the LD and HD-CBCT. CONCLUSIONS: Accuracy of measurements of bone loss shows no clinical noticeable effects depending on the CBCT volume in this ex vivo study. There appears to be no relevant advantage of SV over LV, neither in HD-CBCT nor in LD-CBCT and additionally no relevant advantage of HD versus LD in visualizing marginal bone loss.

Low-dose CBCT imaging of alveolar buccal bone adjacent to mandibular anterior teeth- a pilot study.

OBJECTIVES: Accurate description of buccal bone adjacent to mandibular anterior teeth is helpful for planning and monitoring periodontal and orthodontic treatment. Low-dose cone beam computed tomography (LD-CBCT) imaging has shown promising results for very small dental structures in animals. This study asserts that LD-CBCT is sufficiently accurate to measure buccal alveolar bone adjacent to human mandibular anterior teeth. MATERIALS AND METHODS: Buccal bone level adjacent to 16 mandibular anterior teeth from four human cadavers was measured radiographically using one high-dose (HD) CBCT protocol and two LD-CBCT protocols. The resulting radiographic measurements of buccal bone height (bl) and thickness (bt) were compared with reference probe and reflected-light microscopy measurements. Measurement medians and Bland-Altman plots were calculated, and a linear mixed model was used to compare raters and imaging modalities. RESULTS: All regression coefficients were approximately 0, indicating high interrater, intrarater, and intermodality agreement. No significant differences were found between reference measurements and CBCT protocols. The mean differences for bl measurements were 0.07 mm (rater 1 [r1]) and 0.12 mm (rater 2 [r2]) for HD-CBCT; 0.07 mm (r1) and 0.13 mm (r2) for LD-CBCT-1; and 0.02 mm (r1) and 0.01 mm (r2) for LD-CBCT-2. For bt measurements, mean differences were 0.02 mm (r1) and 0.02 mm (r2) for HD-CBCT; 0.01 mm (r1) and 0.01 mm (r2) for LD-CBCT-1; and 0.00 mm (r1) and 0.01 mm (r2) for LD-CBCT-2. CONCLUSIONS: Within the limitations of the present study, LD-CBCT seems to be a precise method for describing buccal bone and its thickness adjacent to mandibular anterior teeth in this experimental setting. CLINICAL RELEVANCE: For the first time, this study showed LD-CBCT produces excellent results and is a reliable modality for imaging buccal bone in vitro. If clinical studies confirm these results, LD-CBCT could enable better treatment planning and monitoring at a radiation dose that is far lower than that of conventional HD-CBCT but similar to that of panoramic views.

Neuronal Guidance Molecules in Bone Remodeling and Orthodontic Tooth Movement.

During orthodontic tooth movement, mechanically induced remodeling occurs in the alveolar bone due to the action of orthodontic forces. The number of factors identified to be involved in mechanically induced bone remodeling is growing steadily. With the uncovering of the functions of neuronal guidance molecules (NGMs) for skeletal development as well as for bone homeostasis, NGMs are now also among the potentially significant factors for the regulation of bone remodeling during orthodontic tooth movement. This narrative review attempts to summarize the functions of NGMs in bone homeostasis and provides insight into the currently sparse literature on the functions of these molecules during orthodontic tooth movement. Presently, four families of NGMs are known: Netrins, Slits, Semaphorins, ephrins and Eph receptors. A search of electronic databases revealed roles in bone homeostasis for representatives from all four NGM families. Functions during orthodontic tooth movement, however, were only identified for Semaphorins, ephrins and Eph receptors. For these, crucial prerequisites for participation in the regulation of orthodontically induced bone remodeling, such as expression in cells of the periodontal ligament and in the alveolar bone, as well as mechanical inducibility, were shown, which suggests that the importance of NGMs in orthodontic tooth movement may be underappreciated to date and further research might be warranted.

OCT evaluation of orthodontic surface sealants: a 12-month follow-up randomized clinical trial.

OBJECTIVES: The aim of this single-center randomized controlled trial (NCT03753256) was to assess orthodontic surface sealant layer thickness and integrity in vivo during a 12-month follow-up by optical coherence tomography (OCT). MATERIALS AND METHODS: Using a split-mouth design, quadrants of 20 patients treated with fixed orthodontic appliances were included. Quadrants were randomly assigned to the sealants Pro Seal® (PS) or Opal® Seal™ (OS). OCT scans were performed immediately after the application of the sealants and after 3, 6, 9, and 12 months. Sealant layer thicknesses and their integrity were determined at 5 regions of interest (ROIs) known for high risks of demineralization. Sealant integrity loss was determined using a self-developed scale. RESULTS: A total of 16 patients successfully completed the study. The studied sealants showed significant differences in initial layer thickness. Mean layer thickness was significantly lower for PS (67.8 µm, (95% CI, 56.1-79.5)) than for OS (110.7 µm, (95% CI, 97.3-124.1)). Layer thickness loss was significant after 3 months for PS and after 6 months for OS. Sealant integrity was compromised in more than 50% of the ROIs already after 3 months for both sealants. CONCLUSIONS: Patients treated with fixed orthodontic surface sealants lost the integrity of the protective layer in more than 50% of cases after 3 months, and the layer thickness of the sealants was significantly reduced after 3-6 months. CLINICAL RELEVANCE: The protective effect against demineralization lesions of orthodontic sealants in patients treated with fixed appliances appears to be limited in time. Further preventive measures should be investigated. TRIAL REGISTRATION: ClinicalTrials.gov (NCT03753256).

Evaluation of magnetic resonance imaging artifacts caused by fixed orthodontic CAD/CAM retainers-an in vitro study.

OBJECTIVES: Magnetic resonance imaging (MRI) image quality can be severely impaired by artifacts caused by fixed orthodontic retainers. In clinical practice, there is a trend towards using computer-aided design/computer-aided manufacturing (CAD/CAM) retainers. This study aimed to quantify MRI artifacts produced by these novel CAD/CAM retainers. MATERIAL AND METHODS: Three CAD/CAM retainers and a stainless-steel retainer ("Twistflex"; clinical reference standard) were scanned in vitro at 3-T MRI using a high-resolution 3D sequence. The artifact diameters and three-dimensional artifact volumes (AV) were determined for all mandibular (AVmand) and maxillary (AVmax) retainers. Moreover, the corresponding ratio of artifact volume to retainer volume (AV/RVmand, AV/RVmax) was calculated. RESULTS: Twistflex caused large artifact volumes (AVmand: 13530 mm3; AVmax: 15642 mm3; AV/RVmand: 2602; AV/RVmax: 2235). By contrast, artifact volumes for CAD/CAM retainers were substantially smaller: whereas artifact volumes for cobalt-chromium retainers were moderate (381 mm3; 394 mm3; 39; 31), grade-5 titanium (110 mm3; 126 mm3; 12; 12) and nickel-titanium (54 mm3; 78 mm3; 12; 14) both produced very small artifact volumes. CONCLUSION: All CAD/CAM retainers caused substantially smaller volumes of MRI artifacts compared to Twistflex. Grade-5 titanium and nickel-titanium CAD/CAM retainers showed the smallest artifact volumes. CLINICAL RELEVANCE: CAD/CAM retainers made from titanium or nickel-titanium may not relevantly impair image quality in head/neck and dental MRI. Artifacts caused by cobalt-chromium CAD/CAM retainers may mask nearby dental/periodontal structures. In contrast, the large artifacts caused by Twistflex are likely to severely impair diagnosis of oral and adjacent pathologies.

A Potential Role of Semaphorin 3A during Orthodontic Tooth Movement.

BACKGROUND: Induced tooth movement during orthodontic therapy requires mechano-induced bone remodeling. Besides various cytokines and growth-factors, neuronal guidance molecules gained attention for their roles in bone homeostasis and thus, potential roles during tooth movement. Several neuronal guidance molecules have been implicated in the regulation of bone remodeling. Amongst them, Semaphorin 3A is particular interesting as it concurrently induces osteoblast differentiation and disturbs osteoclast differentiation. METHODS: Mechano-regulation of Sema3A and its receptors PlexinA1 and Neuropilin (RT-qPCR, WB) was evaluated by applying compressive and tension forces to primary human periodontal fibroblasts (hPDLF) and alveolar bone osteoblasts (hOB). The association of the transcription factor Osterix (SP7) and SEMA3A was studied by RT-qPCR. Mechanisms involved in SEMA3A-mediated osteoblast differentiation were assessed by Rac1GTPase pull-downs, ß-catenin expression analyses (RT-qPCR) and nuclear translocation assays (IF). Osteogenic markers were analyzed by RT-qPCR. RESULTS: SEMA3A, PLXNA1 and NRP1 were differentially regulated by tension or compressive forces in hPDLF. Osterix (SP7) displayed the same pattern of regulation. Recombinant Sema3A induced the activation of Rac1GTPase, the nuclear translocation of ß-catenin and the expression of osteogenic marker genes. CONCLUSION: Sema3A, its receptors and Osterix are regulated by mechanical forces in hPDLF. SEMA3A upregulation was associated with Osterix (SP7) modulation. Sema3A-enhanced osteogenic marker gene expression in hOB might be dependent on a pathway involving Rac1GTPase and ß-catenin. Thus, Semaphorin 3A might contribute to bone remodeling during induced tooth movement.

Demineralization detection in orthodontics using an ophthalmic optical coherence tomography device equipped with a multicolor fluorescence module.

OBJECTIVES: Demineralizations such as white spot lesions are among the most prevalent side effects during orthodontic treatment. Fluorescence devices, including quantitative light-induced fluorescence (QLF), exploiting the intrinsic fluorescence of enamel and teeth and most recently optical coherence tomography (OCT) were introduced for early demineralization detection. In addition to near-infrared OCT scanning, multicolor modules allow for imaging with different laser wavelengths and the detection of reflective- and fluorescent light. The aim of this study was to evaluate a modified multicolor ophthalmic OCT device for the detection of early carious lesions in vitro and in vivo. MATERIALS AND METHODS: Twenty-seven extracted lesion free human teeth were randomly assigned to three different demineralization protocols. Carious lesion detection was performed using macrophotography, OCT, and reflectance/fluorescence imaging using green laser and blue laser light. In addition, teeth of 5 orthodontic patients were OCT scanned, and fluorescence imaging using blue laser light was performed to assess demineralization after orthodontic therapy. RESULTS: Both in vitro and in vivo, OCT allowed for precise determination of lesion depth and enamel loss. Fluorescence imaging using blue laser light was most sensitive for the detection of early demineralization in vitro and in vivo. However, established and severe demineralizations were also reliably detected by macrophotography in vitro and in vivo. CONCLUSION: Demineralization can be detected with high sensitivity using blue fluorescence imaging with multicolor OCT devices. CLINICAL RELEVANCE: In the future, OCT fluorescence imaging might be considered for longitudinal monitoring of dental hard tissue during orthodontic treatment in clinical trials.

Comparison of acupuncture on specific and non-specific points for the treatment of painful temporomandibular disorders: A randomised controlled trial.

BACKGROUND AND OBJECTIVE: The aim of this single-centre, two-arm, parallel-group, double-blinded, randomised controlled trial was to investigate the disputed specific effectiveness of acupuncture by comparing acupuncture on specific and non-specific points among patients with non-chronic, painful TMDs. METHODS: Following predefined eligibility criteria, 49 consecutive patients of both sexes were recruited to the study. All subjects were diagnosed with a non-chronic (Graded Chronic Pain Scale grade <3) painful TMD, as assessed using the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Patients were randomly assigned to group A (acupuncture on specific points) or group B (acupuncture on non-specific points) after the initial examination (T0). Both acupuncture treatment sessions were conducted by a trained dentist once a week for four weeks. The examination was repeated five weeks (T5) after T0 by one calibrated examiner who was unaware of the study groups. Characteristic pain intensity (CPI) was evaluated as the main outcome criterion and compared between times and treatment groups by means of non-parametric tests (significance level set at P = .05). Secondary outcomes comprised the maximum corrected active mouth-opening without pain (MAO); patients' expectations regarding acupuncture treatment and pain development; depressivity; and oral health-related quality of life (OHRQoL). RESULTS: A total of 41 patients (38 female) successfully completed the study (mean age: 40.17 ± 16.61). The two groups did not differ significantly at any time in terms of age and CPI. However, CPI was significantly (P < .05) lower at T5 than at T0 for both groups (29.66 and 30.35% lower in group A and group B, respectively). An increase in MAO was observed at T5 for both groups but was significant for group B only (P = .016). All patients had positive expectations of acupuncture therapy, and the two groups did not differ significantly at T5 with regard to the extent to which their expectations had been fulfilled by the treatment (P = .717). Comparison of T0 and T5 showed a statistically significant reduction of depressivity for group A (P = .0205), but no significant change for group B (P = .329). At T5, OHRQoL had improved significantly for both groups (group A, P = .018; group B, P < .001) compared with at T0. CONCLUSIONS: Acupuncture on both specific and non-specific points reduces the non-dysfunctional pain of TMD patients. The effect of acupuncture on painful TMD cannot be attributed to the specific point selection.

Abrasion of Pro Seal® and Opal® Seal™ by professional tooth cleaning protocols: results from an in vitro study and a randomized controlled trial.

BACKGROUND: The integrity of orthodontic surface sealants after professional tooth cleaning (PTC) has previously only been evaluated in vitro. Recently, we have shown that optical coherence tomography (OCT) can successfully be used for the longitudinal assessments of sealant thickness in vitro and in vivo. OBJECTIVES: Thus, the aim of the present study was to assess the sealant thickness after PTC in vitro and in vivo by OCT. TRIAL DESIGN: Single-centre four-arm parallel-group randomized controlled trial. METHODS: Ninety-six extracted human teeth were randomly assigned to the surface sealants Pro Seal® (PS) and Opal® Seal™ (OS) and to PTC protocols: (1) polishing with brush and prophy paste (Cleanic®) or (2) erythritol air-polishing. Sealant thickness was assessed by OCT immediately after application (baseline), after thermocycling and after polishing for totals of 5, 10, 15, 30, 60, 90, and 120 seconds. Additionally, a clinical trial was conducted. Therefore, using a split-mouth design, quadrants of 20 patients and PTC protocols were randomized by an external randomization centre using computer generated tables to assign the surface sealants and PTC protocols. Sealant thicknesses were analysed at baseline, before and after PTC. Due to the optical properties of sealants, a complete blinding was not feasible. RESULTS: In vitro both sealants revealed significant layer thickness losses after both PTC protocols. PS lost 0.77 µm/s [95% CI (confidence interval): 0.67, 0.87] from air-polishing and 0.43 µm/s (95% CI: 0.37, 0.49) from polishing with brush while OS lost 0.44 µm/s (95% CI: 0.32, 0.55) from air-polishing and 0.79 µm/s (95% CI: 0.68, 0.89) from polishing with brush of layer thickness. Sealant thickness loss of was significantly higher after erythritol air-polishing for PS and after polishing with brush for OS. The results of a concurrent randomized controlled trial (RCT) were comparable to those achieved in the in vitro part of this study. LIMITATIONS: Long-term surface sealant abrasion should be validated by additional RCTs. CONCLUSIONS: For PTC on surface sealant treated teeth, low abrasive protocols should be used. Air-polishing should be avoided on PS protected teeth and polishing with brush on OS treated teeth. TRIAL REGISTRATION: ClinicalTrials.gov NCT03753256.

Assessing abrasion of orthodontic surface sealants using a modified ophthalmic optical coherence tomography device.

OBJECTIVE: Optical coherence tomography (OCT) is a clinical standard in ophthalmology. Currently, its application in dentistry is gaining increasing interest. In this study, we tested the possibility to use a modified commercially available spectral domain OCT (SD-OCT) to assess the layer thickness of orthodontic surface sealants. MATERIALS AND METHODS: Reference samples of surface sealants for calibration and repeatability testing were measured using a micrometer screw. SD-OCT measurements were compared with micro-CT and light microscopic analyses. After validating the calibration of the SD-OCT, surface sealant layer thickness after aging (thermo cycling) and simulation of professional tooth cleaning (PTC) was assessed using the SD-OCT on 45 extracted teeth assigned to three test groups (n = 15 each): Light Bond™ Sealant, Pro Seal®, and Opal® Seal. RESULTS: SD-OCT showed excellent repeatability and accuracy for measurements of surface sealant layer thickness. Compared with micro-CT, SD-OCT showed better accordance with the reference measurements. The analysis of surface sealants after thermo cycling and PTC revealed poor resistance of Light Bond after only aging and demonstrated substantial wear of all sealants after aging and PTC. CONCLUSION: Imaging using commercially available ophthalmic SD-OCT might represent a suitable non-invasive methodology for longitudinal assessments of surface sealant layer thickness in vitro and in vivo. CLINICAL RELEVANCE: SD-OCT might be a suitable non-invasive method for longitudinal assessments of surface sealant durability in clinical trials.

Effects of staining and polishing on different types of enamel surface sealants.

OBJECTIVE: To assess surface discoloration of four enamel sealants based on different chemical compositions after exposure to artificial aging and staining solutions. Furthermore, their cleanability after polishing will be evaluated. MATERIALS AND METHODS: Selected sealants were a composite resin-based sealant with fillers (Pro Seal), a composite resin-based sealant without fillers (Light BondSealant), a resin-modified glass ionomer-based sealant (ClinproXT Varnish) and a silicon-based sealant (Protecto). Natural teeth served as medium. Immersion solutions were water, juice, tea, and turmeric. In a standardized setting, all samples were measured seven times with a spectroradiometer (Photoresearch PR670) at baseline, after thermocycling; 7 days; 2 and 4 weeks of immersion; and after finally polishing. RESULTS: Thermocycling had no significant effect on color stability. After exposure to staining solutions, all sealed surfaces showed significant color changes. Color change predominately occurred for all sealants in the first week of staining (P ≤ .01). Best resistance to staining decreased as follows: Protecto > Light Bond Sealant > ProSeal > Clinpro XT Varnish. Surface cleaning by polishing significantly reduced the color change. CONCLUSION: Sealed enamel surfaces are prone to discoloration, which is most prominent in filled composite and glass-ionomer-based sealants. Staining can be reduced by polishing; however, in this in vitro setting the original color could not be restored. CLINICAL SIGNIFICANCE: Enamel sealants might exert adverse effects in terms of discoloration. This should be taken into consideration by clinicians and patients, particularly when sealants are applied in esthetically critical areas.

Efficiency of powered systems for interproximal enamel reduction (IER) and enamel roughness before and after polishing-an in vitro study.

OBJECTIVE: This aims to evaluate the efficiency of three different powered interproximal enamel reduction (IER) systems and to assess enamel roughness before and after polishing using different polishing times. MATERIAL AND METHODS: Four metal strips of the G5 ProLign Set (swissdentacare, SDC, Grancia, Switzerland), four segmental discs of the ASR-Set 4594 and two sonic tips of the SonicLine Set (both Gebr. Basseler GmbH & Co. KG, Komet, Lemgo, Germany) were evaluated. Human extracted incisors served as the medium. Enamel reduction was determined in five intervals of 15 s each. Polishing was performed for 15 and 30 s using the manufacturers' recommended polishing systems. Enamel roughness (Ra) was quantitatively assessed by confocal laser scanning microscopy (CLSM). RESULTS: Significant differences in terms of enamel reduction were found among the working ends of all tested systems. The time needed to remove 0.1, 0.2 and 0.3 mm of enamel was determined. Surface analysis showed significantly higher mean Ra values for nine out of ten working ends before polishing. This was still the case for five working ends after 15 s and for two after 30 s of polishing. CONCLUSION: The graining and the system used have a significant influence on enamel reduction. The time needed for polishing depends on the last working end used; a polishing time of 30 s is not always appropriate. CLINICAL RELEVANCE: Knowledge about the cutting efficiency of powered IER working ends might help the clinician to estimate better the amount of enamel reduction during the stripping process.

Dental imaging in clinical photon-counting CT at a quarter of DVT dose.

OBJECTIVE: To investigate the image quality of a low-dose dental imaging protocol in the first clinical photon-counting computed tomography (PCCT) system in comparison to a normal-dose acquisition in a digital volume tomography (DVT) system. MATERIALS AND METHODS: Clinical PCCT systems offer an increased spatial resolution compared to previous generations of clinical systems. Their spatial resolution is in the order of dental DVT systems. Resolution-matched acquisitions of ten porcine jaws were performed in a PCCT (Naeotom Alpha, Siemens Healthineers) and in a DVT (Orthophos XL, Dentsply Sirona). PCCT images were acquired with 90 kV at a dose of 1 mGy CTDI16 cm. DVT used 85 kV at 4 mGy. Image reconstruction was performed using the standard algorithms of each system to a voxel size of 160 × 160 × 200 µm. The dose-normalized contrast-to-noise ratio (CNRD) was measured between dentine and enamel and dentine and bone. Two readers evaluated overall diagnostic quality of images and quality of relevant structures such as root channels and dentine. RESULTS: CNRD is higher in all PCCT acquisitions. CNRD is 37 % higher for the contrast dentine-enamel and 31 % higher for the dentine-bone contrast (p < 0.05). Overall diagnostic image quality was higher for PCCT over DVT (p < 0.02 and p < 0.04 for readers 1 and 2). Quality scores for anatomical structures were higher in PCCT compared to DVT (all p < 0.05). Inter- and intrareader reproducibility were acceptable (all ICC>0.64). CONCLUSIONS: PCCT provides an increased image quality over DVT even at a lower dose level and might enable complex dental imaging protocols in the future. CLINICAL SIGNIFICANCE: The evolution of photon-counting technology and it's optimization will increasingly move dental imaging towards standardized 3D visualizations providing both minimal radiation exposure and high diagnostic accuracy.

Ex-vivo imaging of buccal and oral periodontal bone with low-dose CBCT in porcine jaws.

OBJECTIVES: New CBCT devices have been developed which can provide "low-dose CBCTs (LD-CBCT)". Aim of this study is to investigate the suitability of LD-CBCT for measurement of alveolar buccal/oral bone. METHODS AND MATERIALS: Vestibular and oral bone loss of the teeth of seven porcine mandibles free of soft tissues were investigated by Micro-CT and three CBCT-modes: high-dose (HD), standard-dose (SD) and low-dose (LD). Radiographic measurements of bone loss (bl) and vestibular and oral bone thickness (bt) were made by two raters at 69 sites. Measurement means and differences, Intraclass correlation (ICC) and Bland-Altman plots were calculated. RESULTS: ICCs between raters(r) concerning bl were 0.954 for HD, 0.949 for SD and 0.945 for LD; concerning bt they were 0.872 for HD, 0.845 for SD and 0.783 for LD. Means of differences of bt measurements were -0.01 mm(r1)/0.00 mm(r2) for HD, 0.04 mm(r1)/0.02 mm(r2) for SD and 0.02 mm(r1)/0.04 mm(r2) for LD; for bl measurements they were 0.06 mm(r1)/0.05 mm(r2) for HD, -0.01 mm(r1)/0.13 mm(r2) for SD and 0.07 mm(r1)/0.16 mm(r2) for LD.Linear regression indicates no noticeable differences between methods and the raters with respect to bl and bt. CONCLUSIONS: Relating to the CBCT-device used in this study, LD-CBCT is a promising method to detect and describe buccal and oral periodontal bl and bt. Further studies with human anatomic structures must confirm these results.

Imaging furcation defects with low-dose cone beam computed tomography.

Different cone beam computed tomography (CBCT) protocols have shown promising results for imaging furcation defects. This study evaluates the suitability of low-dose (LD)-CBCT for this purpose. Fifty-nine furcation defects of nine upper and 16 lower molars in six human cadavers were measured by a high-dose (HD)-CBCT protocol, a LD-CBCT protocol, and a surgical protocol. HD-CBCT and LD-CBCT measurements were made twice by two investigators and were compared with the intrasurgical measurements, which served as the reference. Furcation defect volumes generated from HD-CBCT and LD-CBCT imaging were segmented by one rater. Cohen's kappa and intraclass correlation coefficient (ICC) values were calculated to determine intra- and interrater reliability. The level of significance was set at α = 0.05. In total, 59 furcation defects of nine upper and 16 lower human molars were assessed. Comparing CBCT furcation defect measurements with surgical measurements revealed a Cohen's kappa of 0.5975 (HD-and LD-CBCT), indicating moderate agreement. All furcation defects identified by HD-CBCT were also detected by LD-CBCT by both raters, resulting in a Cohen's kappa of 1. For interrater agreement, linear furcation defect measurements showed an ICC of 0.992 for HD-CBCT and 0.987 for LD-CBCT. The intrarater agreement was 0.994(r1)/0.992(r2) for HD-CBCT and 0.987(r1)/0.991(r2) for LD-CBCT. The intermodality agreement was 0.988(r1)/0.991(r2). Paired t-test showed no significant differences between HD-CBCT and LD-CBCT measurements. LD-CBCT is a precise and reliable method for detecting and measuring furcation defects in mandibular and maxillary molars in this experimental setting. It has the potential to improve treatment planning and treatment monitoring with a far lower radiation dose than conventional HD-CBCT.

In-vitro assessment of the efficiency of cold atmospheric plasma on decontamination of titanium dental implants.

BACKGROUND: The aim of the current study was to comparatively assess the efficiency of three different adjunctive therapy options (cold atmospheric plasma, [CAP], photodynamic therapy [PDT] and chemical decontamination via 35% phosphoric acid gel [PAG]) on decontamination of titanium implant surfaces in-vitro. MATERIALS AND METHODS: Implants were inserted in concavities of four mm in depth mimicking a bone defect at the implant recipient site. In each model, two implants were inserted in the fourth and one implant in the third quadrants. After contamination with E. faecalis, the first group has been treated with CAP for 3 min, the second group with 35% PAG (and the third group with PDT. After treatment, quantification of bacterial colonization was assessed by quantification via colony forming units and qualitatively by fluorescence microscopy and scanning electron microscopy. RESULTS: With a mean value of 1.24 × 105 CFU/ml, the CAP treated implants have showed the least microorganisms. The highest number of CFU was found after PDT with mean value of 8.28 × 106 CFU/ml. For the implants that were processed with phosphoric acid, a mean value of 3.14 × 106 CFU/ml could be detected. When the groups were compared, only the CAP and PDT groups differed significantly from each other (p = 0.005). CONCLUSION: A complete cleaning of the micro-textured implant surface or the killing of the bacteria could not be achieved by any of the investigated treatment options, thus bacteria in the microstructure of the titanium surface cannot be completely reached by mechanical and physico-chemical processes. CLINICAL RELEVANCE: The main goal of the adjunctive peri-implantitis treatment is the decontamination of the implant surface. However, there is still an ongoing need to define the most appropriate adjunctive therapy method. Due to its antimicrobial effects, CAP combined with mechanical debridement could be a feasible treatment modality in the management of peri-implantitis.

Dental imaging using an ultra-high resolution photon-counting CT system.

Clinical photon-counting CT (PCCT) offers a spatial resolution of about 200 µm and might allow for acquisitions close to conventional dental CBCTs. In this study, the capabilities of this new system in comparison to dental CBCTs shall be evaluated. All 8 apical osteolysis identified in CBCT were identified by both readers in all three PCCT scan protocols. Mean visibility scores showed statistical significant differences for root canals(p = 0.0001), periodontal space(p = 0.0090), cortical(p = 0.0003) and spongious bone(p = 0.0293) in favor of high and medium dose PCCT acquisitions. Overall, both devices showed excellent image quality of all structures assessed. Interrater-agreement showed high values for all protocols in all structures. Bland-Altman plots revealed a high concordance of both modalities with the reference measurements. In vitro, ultra-high resolution PCCT can reliably identify different diagnostic entities and structures relevant for dental diagnostics similar to conventional dental CBCT with similar radiation dose. Acquisitions of five cadaveric heads were performed in an experimental CT-system containing an ultra-high resolution PC detector (0.25 mm pixel size in isocenter) as well as in a dental CBCT scanner. Acquisitions were performed using dose levels of 8.5 mGy, 38.0 mGy and 66.5 mGy (CTDI16cm) in case of PCCT and of 8.94 mGy (CTDI16cm) in case of CBCT. The quality of delineation of hard tissues, root-canals, periodontal-space as well as apical osteolysis was assessed by two readers. Mean visibility scores and interrater-agreement (overall agreement (%)) were calculated. Vertical bone loss (bl) and thickness (bt) of the buccal bone lamina of 15 lower incisors were measured and compared to reference measurements by ore microscopy and clinical probing.

Non-invasive three-dimensional thickness analysis of oral epithelium based on optical coherence tomography-development and diagnostic performance.

OBJECTIVES: Evaluating structural changes in oral epithelium can assist with the diagnosis of cancerous lesions. Two-dimensional (2D) non-invasive optical coherence tomography (OCT) is an established technique for this purpose. The objective of this study was to develop and test the diagnostic accuracy of a three-dimensional (3D) evaluation method. METHODS: The oral lip mucosa of 10 healthy volunteers was scanned using an 870-nm spectral-domain OCT device (SD-OCT) with enhanced depth imaging (EDI). Four raters semi-automatically segmented the epithelial layer twice. Thus, eighty 3D datasets were created and analyzed for epithelial thickness. To provide a reference standard for comparison, the raters took cross-sectional 2D measurements at representative sites. The correlation between the 2D and 3D measurements, as well as intra- and inter-rater reliability, were analyzed using intraclass correlation coefficients (ICC). RESULTS: Mean epithelial thickness was 280 ± 64µm (range 178-500 µm) and 268 ± 49µm (range 163-425 µm) for the 2D and 3D analysis, respectively. The inter-modality correlation of the thickness values was good (ICC: 0.76 [0.626-0.846]), indicating that 3D analysis of epithelial thickness provides valid results. Intra-rater and inter-rater reliability were good (3D analysis) and excellent (2D analysis), suggesting high reproducibility. CONCLUSIONS: Diagnostic accuracy was high for the developed 3D analysis of oral epithelia using non-invasive, radiation-free OCT imaging. CLINICAL SIGNIFICANCE: This new 3D technique could potentially be used to improve time-efficiency and quality in the diagnosis of epithelial lesions compared with the 2D reference standard.

Fixation Methods for Mandibular Advancement and Their Effects on Temporomandibular Joint: A Finite Element Analysis Study.

OBJECTIVES: Bilateral sagittal split osteotomy (BSSO) is a common surgical procedure to correct dentofacial deformities that involve the mandible. Usually bicortical bone fixation screw or miniplates with monocortical bone fixation screw were used to gain stability after BSSO. On the other hand, the use of resorbable screw materials had been reported. In this study, our aim is to determine first stress distribution values at the temporomandibular joint (TMJ) and second displacement amounts of each mandibular bone segment. METHODS: A three-dimensional virtual mesh model of the mandible was constructed. Then, BSSO with 9 mm advancement was simulated using the finite element model (FEM). Fixation between each mandibular segment was also virtually performed using seven different combinations of fixation materials, as follows: miniplate only (M), miniplate and a titanium bicortical bone fixation screw (H), miniplate and a resorbable bicortical bone fixation screw (HR), 3 L-shaped titanium bicortical bone fixation screws (L), 3 L-shaped resorbable bicortical bone fixation screws (LR), 3 inverted L-shaped titanium bicortical bone fixation screws (IL), and 3 inverted L-shaped resorbable bicortical bone fixation screws (ILR). RESULTS: At 9 mm advancement, the biggest stress values at the anterior area TMJ was seen at M fixation and LR fixation at posterior TMJ. The minimum stress values on anterior TMJ were seen at L fixation and M fixation at posterior TMJ. Minimum displacement was seen in IL method. It was followed by L, H, HR, M, ILR, and LR, respectively. CONCLUSION: According to our results, bicortical screw fixation was associated with more stress on the condyle. In terms of total stress value, especially LR and ILR lead to higher amounts.