The building of an accurate 3D physical model of the skull and maxillary dentition.

3D rapid prototyping is a useful tool for the production of 3D models of the human skull taken from cone beam computed tomography scans. Although the accuracy of these models is acceptable the dentition is distorted. The aim of the study is to replace the inaccurately reproduced dental arch of a 3D printed skull model with accurate, correctly proportioned plaster teeth, obtained from a dental impression. 6 dried human skulls were scanned using a Faro laser arm scanner. Impressions of the dentition were taken using silicone impression material. Plaster dental casts were produced using dental stone. Following removal of the inaccurate dentition from the 3D printed skull model, the corresponding plaster dental cast was attached to the 3D printed skull model using a custom designed technique. The six modified 3D printed skull models with replaced dentition were laser scanned using a Faro arm. VRmesh software was used to superimpose the laser scanned skull images

Caries progression in non-cavitated fissures after infiltrant application: a 3-year follow-up of a randomized controlled clinical trial

Objectives To evaluate the efficacy of a conservative treatment to prevent the progression of caries using an infiltrant on non-cavitated pit and fissures. Material and Methods This controlled clinical trial selected 23 volunteers with clinically and radiographically non-cavitated occlusal caries among patients presenting a “rather low” to “very high” caries risk. Eighty-six teeth were randomly divided into two experimental groups: teeth receiving a commercial pit-and-fissure sealant (Alpha Seal-DFL) and contralateral teeth receiving Icon infiltrant (DMG). Caries progression was monitored by clinical (laser fluorescence caries detection) and radiographic examination at 12-month intervals over a period of 3 years of monitored caries progression. Probing the sealing materials to detect areas of retention was also used to evaluate marginal integrity. Results Statistical analysis showed no difference in caries progression using laser fluorescence caries detection when both materials were compared, regardless of the evaluation times (p>;0.05). No significance was observed when the marginal sealant integrity of both materials was compared, regardless of the evaluation time (

Accuracy of Digital Impressions at Varying Implant Depths: An In-vitro Study

Introduction: Implants placed at variable depths may vary the amount of visible scannable surface of a scan body. Intraoral scanner technology uses advanced optical principles to record the surface of the scan body to accurately capture the implant position. Purpose: To investigate the effect implant placement depth has on the accuracy of digital implant impressions using an intraoral scanner. Materials & Methods: A partially edentulous gypsum master model was fabricated to allow the positioning of a single implant analog at different depths. Four groups based on the planned implant depths of 0, 3, 6 and 7mm and corresponding visibility of the scan body at 9, 6, 3 and 2mm were created. The model was digitized with a laboratory scanner for the reference scan and with an intraoral scanner to generate 15 test scans per group. The test scans were superimposed onto the reference scan using the best fit algorithm to analyze and measure the positional (dXYZ) and angular deviation (d⍬) of the scan body using 3D metrology software. Statistical analysis was performed using a One way ANOVA and pairwise comparison was done with a Tukey-Kramer HSD test. (α= .05) Results:The one-way analysis of variance of the groups for the dXYZ and d⍬ parameters was statistically significant (P Conclusions: The accuracy of digital impressions is influenced by the implant depth and the amount of visibility of the scan body. The trueness and precision of the digital impressions are highest when the implant is placed at 0mm depth with complete visibility of the scan body and decreases with subgingival implant placement

Algorithms & Techniques for Studying In Vitro Oral Biofilms

Dental caries and periodontal disease affect billions of people annually with a global prevalence estimated at 35% and 11%, respectively. Oral biofilms that develop on tooth surfaces and within gingival crevices are a major risk factor. Disease prevention efforts are focused on controlling the overgrowth of biofilms by removal (e.g., toothbrushing), antimicrobial-containing mouth rinses, and dentifrices. A number of laboratory (in vitro) models of biofilms are used to understand how biofilms develop and their response to mouth rinses and dentifrices. However, there are two major limitations to currently available in vitro biofilm model systems. First, there is no biofilm model system validated for the development of representative dental plaque biofilms. Second, there is no standard approach to analyze biofilm images. Current techniques rely on thresholding algorithms that are not designed for fluorescent images. Combined, these limitations can lead to differences in quantification of biofilm outcomes and thus raise questions regarding the relevance of the model system to the “real-world”. This dissertation seeks to bridge the gap between current laboratory techniques and software algorithms and provide investigators additional tools to conduct in vitro oral biofilm studies. First, a distillation of model systems relevant to modern in vitro oral biofilm research is provided. Second, we adapted one of these described model systems, the 24-well BiofluxTM to reproducibly grow multi-species dental biofilms. An objective imaging strategy was further developed to capture all biofilm architectural features. Before analyzing biofilm images, a novel thresholding algorithm, the biovolume elasticity method (BEM), was developed to threshold fluorescent signal. Finally, a software package called Biofilm Architecture Inference Tool (BAIT) was built and evaluated to measure core architectural features of biofilms. In summary, this dissertation describes the modification of a 24-well Bioflux system that facilitates the reproducible development of biofilms. For better visualization and quantification of in vitro biofilms, a novel thresholding algorithm was described. Finally, a software package integrating the BEM thresholding method was developed to measure architectural outcomes. The work presented here represents the outcome of a combinatorial approach to redefine techniques to study oral biofilms, and may also be relevant to the study of biofilms that exist outside the oral cavity.PHDEpidemiological ScienceUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/145880/1/tingluo_1.pd

A pilot study for the digital replacement of a distorted dentition acquired by Cone Beam Computed Tomography (CBCT)

Abstract Introduction: Cone beam CT (CBCT) is becoming a routine imaging modality designed for the maxillofacial region. Imaging patients with intra-oral metallic objects cause streak artefacts. Artefacts impair any virtual model by obliterating the teeth. This is a major obstacle for occlusal registration and the fabrication of orthognathic wafers to guide the surgical correction of dentofacial deformities. Aims and Objectives: To develop a method of replacing the inaccurate CBCT images of the dentition with an accurate representation and test the feasibility of the technique in the clinical environment. Materials and Method: Impressions of the teeth are acquired and acrylic baseplates constructed on dental casts incorporating radiopaque registration markers. The appliances are fitted and a preoperative CBCT is performed. Impressions are taken of the dentition with the devices in situ and subsequent dental models produced. The models are scanned to produce a virtual model. Both images of the patient and the model are imported into a virtual reality software program and aligned on the virtual markers. This allows the alignment of the dentition without relying on the teeth for superimposition. The occlusal surfaces of the dentition can be replaced with the occlusal image of the model. Results: The absolute mean distance of the mesh between the markers in the skulls was in the region of 0.09mm ± 0.03mm; the replacement dentition had an absolute mean distance of about 0.24mm ± 0.09mm. In patients the absolute mean distance between markers increased to 0.14mm ± 0.03mm. It was not possible to establish the discrepancies in the patient’s dentition, since the original image of the dentition is inherently inaccurate. Conclusion: It is possible to replace the CBCT virtual dentition of cadaveric skulls with an accurate representation to create a composite skull. The feasibility study was successful in the clinical arena. This could be a significant advancement in the accuracy of surgical prediction planning, with the ultimate goal of fabrication of a physical orthognathic wafer using reverse engineering

Craniofacial Growth Series Volume 56

https://deepblue.lib.umich.edu/bitstream/2027.42/153991/1/56th volume CF growth series FINAL 02262020.pdfDescription of 56th volume CF growth series FINAL 02262020.pdf : Proceedings of the 46th Annual Moyers Symposium and 44th Moyers Presymposiu

The Methodological Issues of the C.S.I Effect and it’s Controversial Impact on Criminal Investigation

With the rising success of crime-scene related television shows in recent years, and forensic science as a new hot topic in multiple settings, the world of criminal justice faces new complications as this phenomenon continues to grow. This is popularly known as “The C.S.I Effect.” Contrary to belief, much of what the public perceives, or think they know about the operations of law enforcement and the legal system, comes from television. Consequently, as these television programs appeal to greater audiences around the world, increasingly unreasonable expectations are established in the forensic world, both inside and out of the courtroom. In light of this issue, research has discussed the many television shows that have greatly influenced the public perception such as C.S.I, Dexter and Sherlock, and provides a myriad of examples, describing the inconsistencies and flaws that these shows are able to portray in the span of a 40-minute program time slot. With each example, the correct methods, linguistics and techniques that are used in real-world investigations will be explained and the efficiency they provide to criminal cases. Throughout this research, the extension of the C.S.I Effect will be discussed, as well as its impact on a student’s decision in choosing a major in Forensic Science- are they truly satisfied with their choice or disappointed by the reality? Comparative analysis of the C.S.I Effect in the courtroom will be presented, as well as the controversy behind such a theory, will also be discussed at length. The goal of this research is to determine any empirical evidence behind the commonly-held belief that juror expectations for forensic evidence are linked to watching law-related television shows and if there can or cannot be anything to fix this detrimental issue

The Use of Digital Study Models and Perceptions Towards Existing Digital Model Software in Orthodontic Practice

VitaIncludes bibliographical references (pages 31-33)Thesis (M.S.)--School of Dentistry. University of Missouri--Kansas City, 2017Thesis advisors: Mary P. Walker and Jeff NickelThe purpose of this project was to determine what demographic factors, if any, lead to private practice orthodontists creating digital models and then taking the additional step of using these models in treatment planning. A 22-question survey, approved by the UMKC IRB, was constructed and distributed to 2,300 private practice orthodontists by email through the American Association of Orthodontists Partners in Research program. Orthodontic residency graduation year, gender, primary office location, and the use of other digital health records were just a few of the demographics examined in the survey. The survey was divided into two domains, orthodontist demographics and orthodontic office demographics. Additional questions addressed observational items such as the likes and dislikes of the software the orthodontist is currently using. Demographic factors were coded and one-way ANOVA testing was performed with a significance level of α = 0.05. Overall, this study found a statistically significant association between orthodontist and orthodontic office demographics with the practitioner creating digital models and using of these models in treatment planning. In particular, recent orthodontic residents were more likely to create digital models. Orthodontists in certain geographic regions and that used digital dental records were also more likely to create digital models. No other statistically significant results were found and no factors showed a significant association with digital treatment planning; however, the majority of the respondents did create digital models. Observational questions revealed that cost and the preference for plaster models were the two main reasons orthodontists did not use digital models. Another interesting observation was that several orthodontists felt that photographs eliminate the need for models. This survey revealed that the top four programs used for digital models and treatment planning were OrthoCAD®, OrthoTrac®, Invisalign® ClinCheck®, and SureSmile®.Introduction -- Materials and methods -- Results -- Discussion -- Conclusions -- Appendix A. Survey -- Appendix B, Focus group evaluation form -- Appendix C. Survey email prompt -- Appendix D. Informed script for survey -- Appendix E. IRB approval letter -- Appendix F. Composite scoreTitle from PDF of title page, viewed December 13, 201