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Accuracy (trueness and precision) of a dual-structured light facial scanner and interexaminer reliability

The Journal of Prosthetic Dentistry

Available online 7 January 2020

The Journal of Prosthetic Dentistry

Abstract

Statement of problem

Digital waxing procedures should be guided by facial references to improve the esthetic outcome of a restoration. The development of facial scanners has allowed the digitalization of the extraoral soft tissues of the patient’s face. However, the reliability of facial digitizers is questionable.

Purpose

The purpose of this study was to evaluate the accuracy (trueness and precision) of extraoral 3D facial reconstructions performed by using a dual-structured light facial scanner and to measure the interexaminer variability.

Material and methods

Ten participants were included. Six soft-tissue landmarks were determined on each participant, specifically reference (Ref), glabella (Gb), subnasal (Sn), menton (Me), chelion right (ChR), and chelion left (ChL). Interlandmark distances Ref-Sn, Sn-Gb, Ref-Gb, Sn-Me, and ChR-ChL (intercommissural) were measured by 2 different operators by using 2 different methods: directly on the participant’ face (manual group) and digitally (digital group) on the 3D facial reconstruction of the participant (n=20). For the manual group, interlandmark measurements were made by using digital calipers. For the digital group, 10 three-dimensional facial reconstructions were acquired for each participant by using a dual-structured light facial scanner (Face Camera Pro Bellus; Bellus3D). Interlandmark measurements were made by using an open-source software program (Meshlab; Meshlab). Both operators were used to note 10 measurements for each manual and digital interlandmark distance per participant. The intraclass correlation coefficient between the 2 operators was calculated. The Shapiro-Wilk test revealed that the data were not normally distributed. The data were analyzed by using the Mann-Whitney U test.

Results

Significant differences were found between manual and digital interlandmark measurements in all participants. The mean value of the manual and digital group discrepancy was 0.91 ±0.32 mm. The dual-structured light facial scanner tested obtained a trueness mean value of 0.91 mm and a precision mean value of 0.32 mm. Trueness values were always higher than precision mean values, indicating that precision was relatively high. The intraclass correlation coefficient between the 2 operators was 0.99.

Conclusions

The facial digitizing procedure evaluated produced clinically acceptable outcomes for virtual treatment planning. The interexaminer reliability between the 2 operators was rated as excellent, suggesting that the type of facial landmark used in this study provides reproducible results among different examiners.

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Competition and market structure in the dental industry

First Online:

Abstract

We use Survey of Dental Practice data from 1983 to 2012 to examine market power of dentists and hygienists in private practice. Our findings are consistent with a dental market wherein practices use hygienist services as a “loss leader” in order to steer patients into more lucrative dental services, which exhibit the ability to markup price above marginal cost. Both dental care exhibits an elasticity of demand of roughly − 0.2, while hygienist care exhibits and elasticity of demand of nearly − 0.6. Another theme that emerged from our findings is the evidence for significant economies of scale in the dental market. The overall returns to scale parameter of 2.1 suggests significant increasing returns to scale are available to the typical dental practice. Given that the typical practice has 1.5 dentists, the finding is not surprising. While returns to scale diminishes with visit volume, the largest quartile of practices still has meaningful increasing returns to scale of roughly 1.75.
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The incidence of oropharyngeal cancer and rate of human papillomavirus vaccination coverage in Florida, 2011 through 2015.

J Am Dent Assoc. 2020 Jan;151(1):51-58. doi: 10.1016/j.adaj.2019.08.022.

Abstract

OBJECTIVES:

The authors aimed to compare the incidence of oropharyngeal cancer (OPC) from 2011 through 2015 and the rate of human papilloma virus (HPV) vaccination from 2015 through 2017 in the United States overall and in Florida.

METHODS:

Using SEER*Stat software (Surveillance Research Program, National Cancer Institute), the authors calculated age-specific OPC incidence rates for various age groups and age-adjusted rates by sex and race to analyze Surveillance, Epidemiology, and End Results program and National Program of Cancer Registries data. The authors used Joinpoint software (Surveillance Research Program, National Cancer Institute) to model time trends of OPC incidence. They estimated the rate of HPV vaccination among teenagers in Florida and explored the main reasons parents gave for not getting their children vaccinated by means of analyzing data from the National Immunization Survey-Teen. The authors used the χ2 test to determine the association between sociodemographic factors and HPV vaccination and to compare the rate of HPV vaccination in the United States overall with that in Florida.

RESULTS:

The incidence of OPC was higher and the rate of HPV vaccination was lower in Florida than in the United States overall. The OPC incidence rate was highest in those who were aged 50 through 70 years, non-Hispanic white, and male. The rate of being up-to-date on HPV vaccination in Florida was higher among female teenagers than male teenagers but did not differ significantly by other sociodemographic characteristics. The top reason for not getting an HPV vaccination in Florida was that it had not been recommended.

CONCLUSIONS:

The authors found relatively higher and increasing incidence rate of OPC in Florida and lower rate of HPV vaccination among adolescents in Florida than in the nation overall.

PRACTICAL IMPLICATIONS:

The trends illustrated may stimulate policy changes to increase HPV vaccination for children and enhance the understanding of its benefits.

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Visalys CemCore, Kettenbach Dental

Two opposites make a whole
A single composite for cementation and core build-up

This has long been considered impossible, due to conflicting requirements. By
means of patented Active-Connect-Technology (ACT), however, dental specialists
Kettenbach Dental have succeeded in meeting the challenge without
compromising the material. The result is the Visalys® CemCore system, which
enables both adhesive cementation and core build-up to be achieved with just a
few components. Interlinking brands and the business.
Cementation composites need to be as hydrophilic as possible and highly fluid, whereas
core build-up requires a high degree of stability, and a material that swells as little as
possible. Kettenbach Dental has now developed a groundbreaking technology that
simply eliminates the conflicts: Active Connect Technology allows optimal mixing of the
somewhat hydrophobic cementation composite, Visalys® CemCore, with the hydrophilic
Visalys® Tooth Primer, on the damp surface of the tooth.
Despite its hydrophobic properties, the innovative composite achieves a high adhesive
strength without swelling. Visalys® CemCore flows superbly into every clearance, and
yet displays a high degree of stability: gentle application of pressure ensures the degree
of flow required when carrying out restoration, for example. Release the pressure, and
Visalys® CemCore reverts to its firm consistency so that excess material does not expand
and is easy to remove after application.
The Visalys® CemCore system incorporates three basic components: the composite
cement after which it is named, one single-component primer for teeth and another for
restoration. It is exceptionally convenient to use and can be tailored to the application:
Visalys® CemCore is available in the tried and tested automix syringe. The range of five
different colors (Universal, Translucent, Bleach, Opaque and Dark) ensures an excellent
basis for the aesthetic outcome. For securing restorations where outstanding aesthetics
are demanded, additional color-matched try-in pastes are available where required. The
Tooth Primer can be applied direct to dentine or enamel without mixing, and the
Restorative Primer is suitable for pre-treatment of all restoration surfaces.
This makes the Visalys® CemCore system suitable both for cementation and also for core
build-up using a single composite – the Active-Connect-Technology ensures powerful
adhesion with Visalys® Tooth Primer and Visalys® Restorative Primer, while low liquid
absorption ensures a high degree of dimensional stability in the core build-up and hence
a reduced risk of fracture in the final restoration. Visalys® CemCore is available to try in
Universal color with a starter pack, which includes not only the Visalys® CemCore but
also Visalys® Tooth Primer and Visalys® Restorative Primer, along with the required
accessories.
Company information:
Kettenbach GmbH & Co. KG is an internationally orientated family business based in
Eschenburg, Germany. Kettenbach develops, produces and markets medical products
that satisfy the highest quality requirements in its two business areas, Dental and
Medical. For 75 years now, customers have been relying on its products’ universal
applicability and high quality. And the award of ‘TOP 100 company’ is impressive
evidence that Kettenbach still has its finger on the pulse of the age. www.kettenbach.de
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Chairside 3D digital design and trial restoration workflow

The Journal of Prosthetic Dentistry

Available online 7 January 2020

The Journal of Prosthetic Dentistry

Abstract

Different digital tools have been used in clinical practice to assist in the planning and rehabilitation of patients. Some applications (apps) and software programs used in esthetic planning allow simulation of the smile design, improving communication between patients and professionals. Nonetheless, they are usually difficult to use, time-consuming, unattractive to present to the patient, and complicated to link with the 3D workflow. This article presents a new 3D digital smile design app for esthetic planning, smile simulation, chairside 3D virtual wax pattern, and trial restoration performed with portable devices. In this technique description, a facial frontal photograph, a facial scan standard tessellation language (STL) file, and a maxillary intraoral scan STL file were uploaded to the app. The files were calibrated to each other to allow a 3D facially driven smile design project. The definitive maxillary 3D digital waxing of facial templates was exported to a 3D printer as an STL file. The printed resin templates were directly placed in the mouth with flowable composite resin for an immediate trial restoration without the need for casts, silicone guides, or autopolymerizing resin. The workflow presented in this article linked the 3Dapp project to a printer and allowed straightforward chairside trial restorations.

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