[Measuring tooth wear with regular intra-oral 3D scanners: for still in the future, or is it already possible?] / Serie: Innovatieve technieken en ontwikkelingen in de mondzorg. Meten van gebitsslijtage met reguliere 3D-scanners: toekomstmuziek, of al mogelijk?

Quantitative tooth wear measurement is a method of increasing importance when measuring tooth wear progression. The Radboud university medical center has developed a protocol that measures height and volumetric differences on regular 3D-scans. Intra-oral scans were made on patients with tooth wear and superimposed. To assess reliability the precision , as well as intra- and inter-rater precision of the protocol was tested. T-tests were performed to determine the structural and random error. Our findings indicate that the method is precise enough to measure height differences in patients with severe tooth wear progression, or tooth wear with an interval longer than 1 year. The method is not precise enough to measure volumetric changes.

The association between radiological spreading pattern and clinical outcomes in necrotizing external otitis.

Objectives: Necrotizing external otitis (NEO) is a rare infectious disease of the skull base. The purpose of this study was to determine whether clinical outcomes of NEO can be correlated to different infectious spread patterns. Methods: Retrospective chart review from 2010 to 2019 with NEO patients, who were divided into two cohorts: single spreading patterns (group A) or complex spreading patterns (group B) as diagnosed by CT. Clinical symptoms, diagnostic and treatment delay, course of disease, complications, and duration of antibiotic exposure were retrospectively collected from patient records. Results: 41 NEO patients were included, of which 27 patients belonged to group A (66%). The disease-related mortality rate was 12.2% among the entire cohort, no differences were found between group A and B. Higher rates of N.VII (42.9% vs 14.8% P = 0.047) and N. IX palsies were found in group B compared to group A (28.6% vs 3.7%, P = 0.039). The median duration of antibiotic use was significantly different for a complex spreading pattern, clinical recovery and hospitalizations. Complications were associated with higher diagnostic delay and with a complex spread pattern. The median duration of follow-up was 12.0 (IQR 6.0-19.5) months. Conclusion: NEO is a severe disease, with significant mortality and morbidity (cranial nerve palsies). The radiological spread pattern may assist in predicting clinical outcome. Furthermore, complex spread patterns are associated with higher rates of clinical nerve palsies (N. VII and N.IX), complications, surgery rates and longer duration of antibiotic use. Diagnostic delay was associated with mortality, complications and facial palsies. Level of evidence: Level IV.

[Should a metal post always be replaced before a new indirect -restoration?] / Moet een metalen stift altijd worden vervangen voor plaatsing van een kroon?

Before realizing a new indirect restoration on an endodontically treated tooth, present restorations and possible posts need to be assessed. In the case of a metal post, the mismatch in flexural modulus between the dentine and the post might increase the risk of a vertical root fracture. Is it therefore prudent to replace such a metal post, before the fabrication of a new indirect restoration? Two scenarios might be considered to answer this question. First, would a glass fibre post result in a lower risk of failure? Two systematic reviews of the literature comparing glass fibre and metal posts for the short term were contradictory. Second, is the occurrence of a vertical root fracture associated with the presence of a post? Such association could not be established either. On the basis of the current literature, there does not appear to be evidence to support actively replacing a metal post.

Precision of orthodontic cephalometric measurements on ultra low dose-low dose CBCT reconstructed cephalograms.

OBJECTIVES: To analyze differences in variation of orthodontic diagnostic measurements on lateral cephalograms reconstructed from ultra low dose-low dose (ULD-LD) cone beam computed tomography (CBCT) scans (RLC) as compared to variation of measurements on standard lateral cephalograms (SLC), and to determine if it is justifiable to replace a traditional orthodontic image set for an ULD-LD CBCT with a reconstructed lateral cephalogram. MATERIAL AND METHODS: ULD-LD CBCT images and SLCs were made of forty-three dry human skulls. From the ULD-LD CBCT dataset, a lateral cephalogram was reconstructed (RLC). Cephalometric landmarks (13 skeletal and 7 dental) were identified on both SLC and RLC twice in two sessions by two calibrated observers. Thirteen cephalometric variables were calculated. Variations of measurements, expressed as standard deviations of the 4 measurements on SLC and RLC, were analyzed using a paired sample t-test. Differences in the number of observations deviating ≥ 2.0 mm or degrees from the grand mean between SLC and RLC were analyzed using a McNemar test. RESULTS: Mean SDs for 7 out of 13 variables were significantly smaller for SLCs than those for RLCs, but differences were small. For 9 out of 13 variables, there was no significant difference between SLC and RLC for the number of measurements outside the range of 2 mm or degrees. CONCLUSIONS: Based on the lower radiation dose and the small differences in variation in cephalometric measurements on reconstructed LC compared to standard dose LC, ULD-LD CBCT with reconstructed LC should be considered for orthodontic diagnostic purposes. CLINICAL RELEVANCE: ULD-LD CBCT with reconstructed LC should be considered for orthodontic purposes.

Wear behavior of a microhybrid composite vs. a nanocomposite in the treatment of severe tooth wear patients: A 5-year clinical study.

OBJECTIVE: This study aimed to compare the wear behavior of a microhybrid composite vs. a nanocomposite in patients suffering from severe tooth wear. METHODS: A convenience sample of 16 severe tooth wear patients from the Radboud Tooth Wear Project was included. Eight of them were treated with a microhybrid composite (Clearfil APX, Kuraray) and the other eight with a nanocomposite (Filtek Supreme XTE, 3M). The Direct Shaping by Occlusion (DSO) technique was used for all patients. Clinical records were collected after 1 month (baseline) as well as 1, 3 and 5 years post-treatment. The maximum height loss at specific areas per tooth was measured with Geomagic Qualify software. Intra-observer reliability was tested with paired t-tests, while multilevel logistic regression analyses were used to compare odds ratios (OR) of "large amount of wear". RESULTS: Intra-observer reliability tests confirmed that two repeated measurements agreed well (p > 0.136). For anterior mandibular teeth, Filtek Supreme showed significantly less wear than Clearfil APX; in maxillary anterior teeth, Clearfil APX showed significantly less wear (OR material = 0.28, OR jaw position = 0.079, p < 0.001). For premolar and molar teeth, Filtek Supreme showed less wear in bearing cusps, whereas Clearfil APX showed less wear in non-bearing cusps (premolar: OR material = 0.42, OR bearing condition = 0.18, p = 0.001; molar: OR material = 0.50, OR bearing condition = 0.14, p < 0.001). SIGNIFICANCE: Nanocomposite restorations showed significantly less wear at bearing cusps, whereas microhybrid composite restorations showed less wear at non-bearing cusps and anterior maxillary teeth.

Multicomponent mass transport modeling of water desalination by reverse osmosis including ion pair formation.

Reverse Osmosis (RO) is one of the main membrane technologies currently used for the desalination of seawater and brackish water to produce freshwater. However, the mechanism of transport and separation of ions in RO membranes is not yet fully understood. Besides acid-base reactions (i.e., including the H+-ion), at high concentrations, the salt ions can associate and form ion pairs. In this study, we investigate how to include the formation of these ion pairs in the extended Donnan steric partitioning pore model. We study the desalination of a water source where three ion pairs can be formed (NaCl, MgCl+, and MgCl2) and also include water self-dissociation and the carbonate system. The model assumes infinitely fast reactions, which means that the participating ions are locally at chemical equilibrium with one another. A square stoichiometric reaction matrix composed of active species, moieties, and reactions is formulated. As the final constraint equation, we use the charge balance. The model predicts profiles in concentration, flux, and reaction rates across the membrane for all species and calculates the retention per group of ions. Ion pair formation has an influence on the fluxes of individual ions and therefore influences the retention of ions.

The influence of time and irrigant refreshment on biofilm removal from lateral morphological features of simulated root canals.

AIM: To evaluate the effect of irrigant refreshment and exposure time of a 2% sodium hypochlorite solution (NaOCl) on biofilm removal from simulated lateral root canal spaces using two different flow rates. METHODOLOGY: A dual-species biofilm was formed by a Constant Depth Film Fermenter (CDFF) for 96 h in plug inserts with anatomical features resembling an isthmus or lateral canal-like structures. The inserts were placed in a root canal model facing the main canal. NaOCl 2% and demineralized water (control group) were used as irrigant solutions. Both substances were applied at a flow rate of 0.05 and 0.1 mL s-1 . The samples were divided into three groups with zero, one or two refreshments in a total exposure time of 15 min. A three-way analysis of variance (anova) was performed to investigate the interaction amongst the independent variables and the effect of consecutive irrigant refreshment on percentage of biofilm removal. A Tukey post hoc test was used to evaluate the effect of each independent variable on percentage biofilm removal in the absence of statistically significant interactions. RESULTS: For the lateral canal, NaOCl removed significantly more biofilm irrespective of the number of refreshments and exposure time (P = 0.005). There was no significant effect in biofilm removal between the consecutive irrigant refreshments measured in the same biofilm. For the isthmus, NaOCl removed significantly more biofilm irrespective of the number of refreshments and exposure time; both NaOCl and a high flow rate removed significantly more biofilm when the exposure time was analysed (P = 0.018 and P = 0.029, respectively). Evaluating the effect of consecutive irrigant refreshment on the same biofilm, 2% NaOCl, 0.1 mL s-1 flow rate and one or two refreshments removed significant more biofilm (P = 0.04, 0.034 and 0.003, <0.001, respectively). CONCLUSIONS: In this model, refreshment did not improve biofilm removal from simulated lateral root canal spaces. NaOCl removed more biofilm from the lateral canal- and isthmus-like structure. A higher flow rate removed significantly more biofilm from the isthmus-like structure. There was always remaining biofilm left after the irrigation procedures.

A Persistent Foramen of Huschke: A Small Road to Misery in Necrotizing External Otitis.

BACKGROUND AND PURPOSE: Necrotizing external otitis is a serious complication of external otitis with different spreading patterns. A persistent foramen of Huschke is a dehiscence located antero-inferior in the osseous external ear canal and posterior-medial to the temporomandibular joint. This dehiscence can facilitate extension of infection in an anterior pattern next to classic spread along the fissures of Santorini. The aim of this study was to define the prevalence and size of a persistent foramen of Huschke in patients with necrotizing external otitis. MATERIALS AND METHODS: We retrospectively examined 78 CT temporal bone studies (39 patients with necrotizing external otitis, 39 control subjects). The side and presence of the foramen were noted, and its prevalence was calculated. The maximal width of the foramen of Huschke was measured in the axial plane and classified as subtle, mild, moderate, or extensive. RESULTS: A persistent foramen of Huschke was present in 21 patients (26 ears) and 7 control subjects (9 ears). Prevalence was 50% (20/40) and 11.5% (9/78) in affected ears of patients with necrotizing external otitis and control subjects, respectively. Almost all affected ears showed an anterior distribution pattern of necrotizing external otitis. The extensive dehiscence was most common in affected ears. CONCLUSIONS: An anterior necrotizing external otitis spreading pattern is associated with the presence and increased size of a persistent foramen of Huschke. These findings facilitate the theory that a persistent foramen of Huschke is an additional risk factor the development of necrotizing external otitis.

Advanced Imaging Techniques in Skull Base Osteomyelitis Due to Malignant Otitis Externa.

PURPOSE OF REVIEW: To give an up-to-date overview of the strengths and weaknesses of current imaging modalities in diagnosis and follow-up of skull base osteomyelitis (SBO). RECENT FINDINGS: CT and MRI are both used for anatomical imaging, and nuclear techniques aid in functional process imaging. Hybrid techniques PET-CT and PET-MRI are the newest modalities which combine imaging strengths. SUMMARY: No single modality is able to address the scope of SBO. A combination of functional and anatomical imaging is needed, in the case of newly suspected SBO we suggest the use of PET-MRI (T1, T2, T1-FS-GADO, DWI) and separate HRCT for diagnosis and follow-up.

Visualization of hydraulic conditions inside the feed channel of Reverse Osmosis: A practical comparison of velocity between empty and spacer-filled channel.

It is widely accepted that our understanding about the membrane process increases by investigation of the hydraulic conditions of membranes. While numerical studies have been broadly used for this purpose, the experimental studies of a comparable resolution are scarce. In this study, we compared the pressure drop, the temporal and the spatial velocity maps of a spacer-filled channel and an empty channel of the same size to determine the effect of presence of the feeds spacer on hydraulic conditions. The velocity maps are obtained experimentally by using of the Particle Image Velocimetry (PIV) technique. Application of the feed spacer caused 2-8.5 higher pressure drop increase in the experimental conditions in this research. The flow had a spatial distribution in the form of a unimodal symmetric curve of normal distribution in the empty channel and a bimodal asymmetric curve in the spacer-filled channel. The bimodal curve indicates the presence of high- and low-velocity zones. Additionally, the low-velocity zones showed also a lower variation of velocity in time, which indicates the high fouling potential of these locations. The results from this study may be uses for validation of numerical studies.

[The synergy of radiology and CAD/CAM]. / De synergie van radiologie en CAD/CAM.

For treatment planning purposes, data acquired with cone-beam computer tomography and data from other three-dimensional imaging techniques can be combined in a single dataset. With the aid of this combined dataset extensive treatment planning and prosthetic solutions can be realised. The planning and production of the definitive prosthetic solution can then be accomplished using computer-aided design and computer-aided manufacturing technologies. These technological developments are expected to play an increasingly significant role for chair-side solutions.

Comparison of Particle-Associated Bacteria from a Drinking Water Treatment Plant and Distribution Reservoirs with Different Water Sources.

This study assessed the characteristics of and changes in the suspended particles and the associated bacteria in an unchlorinated drinking water distribution system and its reservoirs with different water sources. The results show that particle-associated bacteria (PAB) were present at a level of 0.8-4.5 × 10(3) cells ml(-1) with a biological activity of 0.01-0.04 ng l(-1) ATP. Different PAB communities in the waters produced from different sources were revealed by a 16S rRNA-based pyrosequencing analysis. The quantified biomass underestimation due to the multiple cells attached per particle was ≥ 85%. The distribution of the biologically stable water increased the number of cells per particle (from 48 to 90) but had minor effects on the PAB community. Significant changes were observed at the mixing reservoir. Our results show the characteristics of and changes in suspended PAB during distribution, and highlight the significance of suspended PAB in the distribution system, because suspended PAB can lead to a considerable underestimation of biomass, and because they exist as biofilm, which has a greater mobility than pipe-wall biofilm and therefore presents a greater risk, given the higher probability that it will reach the customers' taps and be ingested.

Full 3-dimensional digital workflow for multicomponent dental appliances: A proof of concept.

BACKGROUND: The authors used a 3-dimensional (3D) printer and a bending robot to produce a multicomponent dental appliance to assess whether 3D digital models of the dentition are applicable for a full digital workflow. METHODS: The authors scanned a volunteer's dentition with an intraoral scanner (Lava Chairside Oral Scanner C.O.S., 3M). A digital impression was used to design 2 multicomponent orthodontic appliances. Biocompatible acrylic baseplates were produced with the aid of a 3D printer. The metal springs and clasps were produced by a bending robot. The fit of the 2 appliances was assessed by 2 experienced orthodontists. RESULTS: The authors assessed both orthodontic appliances with the volunteer's dentition and found the fit to be excellent. CONCLUSIONS: Clinicians can fully produce a multicomponent dental appliance consisting of both an acrylic baseplate and other parts, such as clasps, springs, or screws, using a digital workflow process without the need for a physical model of the patient's dentition. PRACTICAL IMPLICATIONS: Plaster models can be superfluous for orthodontic treatment as digital models can be used in all phases of a full digital workflow in orthodontics. The arduous task of making a multicomponent dental appliance that involves bending wires can possibly be replaced by a computer, design software, a 3D printer, and a bending robot.

[Three dimensional technology and reconstructions of large defects of the jaw]. / Driedimensionale technologie en reconstructies van grote kaakdefecten.

3D technology is increasingly being applied in dentistry and in oral and maxillofacial surgery. An important field of application is reconstructive surgery, especially in the reconstruction of large defects ofthe jaw. In such cases of reconstruction, the goal is the restoration of both the continuity of the defective area and its function. For the functional restoration implant supported dental structures are often employed. In such cases, CAD/CAM superstructures, 3D printed drill and saw templates, anatomical models, wafers and surgical outcome models are used. The combination of the digital planning and the digital fabrication ofsuperstructures and surgical aids offers many preoperative advantages. The use of saw, drill and positioning templates provides for accurate segmentation and implant positioning, by means of which the reconstruction can be carried out in a predictable way.

Validity, reliability, and reproducibility of linear measurements on digital models obtained from intraoral and cone-beam computed tomography scans of alginate impressions.

INTRODUCTION: Digital 3-dimensional models are widely used for orthodontic diagnosis. The aim of this study was to assess the validity, reliability, and reproducibility of digital models obtained from the Lava Chairside Oral scanner (3M ESPE, Seefeld, Germany) and cone-beam computed tomography scans of alginate impressions for tooth-width measurements and the Bolton analysis. METHODS: A digital model, an intraoral scan, and a plaster model were made for each of 22 subjects. Tooth-width measurements on the digital model and the intraoral scan were compared with those on the corresponding plaster models (gold standard). Intraclass correlation coefficients were calculated to determine the interexaminer reliability of the measurements of each method. The anterior and overall Bolton ratios were calculated for each participant and for each method. The paired t test was used to determine the validity. The scanning time for the intraoral scanner was registered and analyzed. RESULTS: Tooth-width measurements of each tooth on the digital models and the intraoral scans did not differ significantly from those on the plaster models (P >0.05). The overall and anterior Bolton ratios from the 2 types of digital models differed significantly from the gold standard (P <0.05). However, the differences never exceeded 1.5 mm; this could be regarded as clinically insignificant. The scanning times of the intraoral scanner decreased significantly with the number of scans performed. CONCLUSIONS: Both intraoral scanning and cone-beam computed tomography scanning of alginate impressions are valid, reliable, and reproducible methods to obtain dental measurements for diagnostic purposes.

Fully 3-dimensional digitally planned reconstruction of a mandible with a free vascularized fibula and immediate placement of an implant-supported prosthetic construction.

BACKGROUND: Reconstruction of craniofacial defects becomes complex when dental implants are included for functional rehabilitation. We describe a fully 3-dimensional (3D) digitally planned reconstruction of a mandible and immediate prosthetic loading with a fibula graft in a 2-step surgical approach. METHODS: A 54-year-old man had development of osteoradionecrosis of the mandible. The resection, cutting and implant placement in the fibula were virtually planned. Cutting/drilling guides were 3D printed, and the suprastructure was computer-aided design and computer-aided manufacturing milled. RESULTS: For the first operation, the implants were inserted in the fibula, and the position was registered by an optical scanning technique that defined the final planning of the suprastructure. For the second operation, the osteoradionecrosis was resected, the fibula was harvested and, with the denture fixed on the preinserted implants, placed in the mandibula guided by the occlusion. CONCLUSION: It was possible to plan a mandibular reconstruction with immediate prosthetic loading completely by 3D virtual techniques.

Digitally designed surgical guides for placing extraoral implants in the mastoid area.

PURPOSE: When planning implant therapy, knowledge of the bone volume in the implant area is needed to plan and place implants in the most appropriate locations from the prosthetic and surgical perspectives. Commercial software for digital planning of implants in the craniofacial region is not yet available. This article describes a method that enables digital planning of extraoral implants in the mastoid region utilizing commercially available computer-aided design (CAD) software and rapid-prototyping techniques to manufacture a corresponding surgical guide. MATERIALS AND METHODS: With the aid of CAD software designed for reverse engineering and three-dimensional animation, digital implant planning based on cone beam computed tomography (CBCT) scanning was performed. On the basis of this planning, surgical guides were digitally designed to facilitate the placement of dental implants in the mastoid area. The guides were fabricated using rapid prototyping. The appropriateness of the digitally designed surgical guides for placing extraoral implants was tested on six human cadaver heads with simulated bilateral ear defects. After implant placement, a second CBCT scan was performed to compare preoperative planning with the actual postoperative implant positions. RESULTS: Twenty-four implants were placed. The surgical guide helped the surgeon to place the implants at the preoperatively planned positions. Comparison of the CBCT scans revealed that adequate accuracy of implant placement was achieved, both for deviation of the neck (1.56 ± 0.56 mm) and the tip (1.40 ± 0.53 mm) of the implant, and for deviation of the angulation of the implant (0.97 ± 2.33 deg). CONCLUSION: The presented method for digitally planning extraoral implants in the mastoid area and designing surgical guides allows for placement of implants in the mastoid area in close proximity to the preoperatively planned implant position. The actual implant positions were satisfactory both surgically and prosthetically.

Digitally designed surgical guides for placing implants in the nasal floor of dentate patients: a series of three cases.

PURPOSE: Insight into the bone volume and position of natural teeth is essential when placing implants to retain nasal prostheses. This paper describes a series of three cases in which a new method was applied for implant placement in the nasal floor of dentate patients using digital planning techniques. MATERIALS AND METHODS: With the aid of computer software, digital planning of implants in the nasal floor based on cone beam computed tomography was performed. Next, surgical guides for implant placement were digitally designed and fabricated using rapid prototyping. RESULTS: In all three patients, implants could be placed and nasal prostheses could be manufactured as planned. All anterior teeth remained vital. Analysis of planning and post-implant placement cone beam computed tomography scans revealed high accuracy of implant placement. CONCLUSION: The applied method allows for reliable implant placement in close proximity to the preoperatively planned implant position.

A prospective non-randomized two-centre study of patients with passive faecal incontinence after birth trauma and patients with soiling after anal surgery, treated by elastomer implants versus rectal irrigation.

AIM: This study is a prospective evaluation of patients with passive faecal incontinence and patients with soiling treated by elastomer implants and rectal irrigation. PATIENTS AND METHODS: Patients with passive faecal incontinence after birth trauma resulting from a defect of the internal sphincter and patients with soiling after previous anal surgery were included. All patients underwent endo-anal ultrasound, magnetic resonance imaging, and anal manometry. The patients with passive faecal incontinence were initially treated by anal sphincter exercises and biofeedback therapy during half a year. The patients completed incontinence scores, a quality of life questionnaire, and a 2-week diary card. RESULTS: The elastomer group consisted of 30 males and 45 females with a mean age of 53 years (25-77). The rectal irrigation group consisted of 32 males and 43 females with a mean age of 50 years (25-74). At 6 months follow-up, 30 patients with soiling of the rectal irrigation group and only nine patients of the elastomer group were completely cured (p = 0.02). Only three patients with passive faecal incontinence were cured in the rectal irrigation group and none in the elastomer group. Three distal migrations of elastomer implants required removal at follow-up. CONCLUSIONS: After patients had performed anal sphincter exercises, no clear improvement of passive faecal incontinence was obtained by elastomer implants or rectal irrigation. However, rectal irrigation is far more effective than elastomer implants in patients with soiling.

[Validity and reliability of digital diagnostic measurements on digital three-dimensional dental models]. / Validiteit en betrouwbaarheid van digitale diagnostische metingen op digitale driedimensionale gebitsmodellen.

Digital three-dimensional dental models are widely used for orthodontic diagnosis. The aim of this clinical study was to assess the validity and reliability of digital diagnostic measurements on digital three-dimensional dental models. Two types of digital three-dimensional dental models and a plaster dental model were made of 10 volunteers. Digital measurements of the tooth width were compared with the physical measurements of the plaster models. None of the digital diagnostic measurements appeared to differ significantly from the physical measurements.