An Assessment of the Fit of a Parabolic Curve to Pre- and Post-Treatment Dental Arches

1989 ◽  
Vol 16 (2) ◽  
pp. 85-93 ◽  
Author(s):  
M. L. Jones ◽  
S. Richmond
Keyword(s):  
Three Dimensional ◽  
Post Treatment ◽  
Dental Arch ◽  
Analysis Program ◽  
Treatment Change ◽  
Parabolic Curve ◽  
Analogue Method ◽  
Cast Analysis

Study casts of the teeth are routinely used for diagnosis and to assess treatment change: the crowding of the teeth or shortage of space available within the dental arch is usually assessed visually. A full cast analysis program has been developed previously, making use of the three-dimensional Reflex Plotter linked to a computer. This study examines the validity of the fit of computer generated parabolic curves to dental arches, as performed in the measurement of crowding. Using a visual analogue method it was found that the parabola appeared to fit lower post-treatment dental arches best. However, reservations regarding the fit of symmetrical curves are expressed and other solutions suggested.

scholarly journals A New Method to Evaluate Trueness and Precision of Digital and Conventional Impression Techniques for Complete Dental Arch

2021 ◽  
Vol 11 (10) ◽  
pp. 4612
Author(s):  
KweonSoo Seo ◽  
Sunjai Kim
Keyword(s):  
Intraclass Correlation ◽  
Three Dimensional ◽  
New Method ◽  
Digital Impression ◽  
Dental Arch ◽  
Digital Models ◽  
Digital Impressions ◽  
Measuring Machine ◽  
Master Model ◽  
Conventional Impression

Purpose: The aim of this study was to present a new method to analyze the three-dimensional accuracy of complete-arch dental impressions and verify the reliability of the method. Additionally, the accuracies of conventional and intraoral digital impressions were compared using the new method. Methods: A master model was fabricated using 14 milled polyetheretherketone cylinders and a maxillary acrylic model. Each cylinder was positioned and named according to its corresponding tooth position. Twenty-five definitive stone casts were fabricated using conventional impressions of the master model. An intraoral scanner was used to scan the master model 25 times to fabricate 25 digital models. A coordinate measuring machine was used to physically probe each cylinder in the master model and definitive casts. An inspection software was used to probe cylinders of digital models. A three-dimensional part coordinate system was defined and used to compute the centroid coordinate of each cylinder. Intraclass correlation coefficient (ICC) was evaluated to examine the reliability of the new method. Independent two sample t-test was performed to compare the trueness and precision of conventional and intraoral digital impressions (α = 0.05). Results: ICC results showed that, the new method had almost perfect reliability for the measurements of the master model, conventional and digital impression. Conventional impression showed more accurate absolute trueness and precision than intraoral digital impression for most of the tooth positions (p < 0.05). Conclusions: The new method was reliable to analyze the three-dimensional deviation of complete-arch impressions. Conventional impression was still more accurate than digital intraoral impression for complete arches.

Three-dimensional dental arch and palatal form changes after extraction and nonextraction treatment. Part 2. Palatal volume and height

2004 ◽  
Vol 126 (1) ◽  
pp. 82-90 ◽  
Author(s):  
Wolfgang Heiser ◽  
Andreas Niederwanger ◽  
Beatrix Bancher ◽  
Gabriele Bittermann ◽  
Nikolaus Neunteufel ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Dental Arch

scholarly journals The Contribution of Cognitive Impulsivity to Criminal Risk

2021 ◽  
Author(s):  
◽  
Rebecca K. Bell
Keyword(s):  
Impulse Control ◽  
Post Treatment ◽  
Trait Anger ◽  
Special Treatment ◽  
Treatment Programme ◽  
Treatment Change ◽  
Anger Control ◽  
Treatment Unit ◽  
Cognitive Behavioural ◽  
Pre Treatment

<p>Impulsivity increases risk for general, violent and sexual offending. Accordingly, helping offenders to become better regulators of their impulses is one goal of offender rehabilitation. In a correctional setting, the assessment of impulsivity focuses on personality and behaviour, but not cognition; cognitive impulse control impairments are inferred from personality styles and behavioural patterns suggestive of acting before thinking. However, empirical findings challenge the validity of inferring cognition from personality and behavioural measures. Additionally, without assessing cognition, practitioners are limited in their ability to isolate which cognitive processes are most impaired and therefore worthy of intervention for individual offenders.  To establish the contribution of cognitive impulse control to criminal risk, a theoretically derived, empirically supported neurocognitive assessment framework was adopted. The framework is based on the notion that impulsive behaviour arises from three, potentially dissociable skill domains that support impulse control: decisionmaking, perceptual and motor impulse control. A cohort of 77 men attending intensive cognitive-behavioural rehabilitation was recruited from four of New Zealand’s prison-based Special Treatment Unit Rehabilitation Programmes (STURPs). A neurocognitive battery of five tasks collectively representing each cognitive impulse control domain was administered before and after the 8-month treatment programme.  Study One explored pre-treatment clinically impaired performance within and across each cognitive impulse control domain. Compared to normative data, performance was typically in the average to below average range, but it was not clinically impaired overall. When performance was clinically impaired, it was most pronounced on tasks requiring cognitive flexibility.  Study Two explored treatment change in cognitive impulse control. The study also compared pre-treatment cognitive impulse control between offenders who went on to complete the treatment programme and those who were prematurely removed for responsivity or conduct-related issues. No pre-treatment cognitive impulse control differences were found between treatment completers and non-completers. Treatment completers displayed small pre-post treatment improvements in some areas of cognitive impulse control, but not others.  Study Three explored cross-sectional and predictive relationships between cognitive impulse control, dynamic criminal risk, trait anger and anger control. Although there was little association between these variables before treatment, some cognitive impulse control outcomes predicted post-treatment dynamic criminal risk, trait anger and anger control. Thus, the evidence suggested that certain aspects of cognitive impulse control might function as facilitators of treatment change.  Together, the findings highlighted the importance of evaluating cognitive impulse control as part of the risk assessment, and clinical formulation process. The findings also suggested that interventions designed to develop cognitive impulse control abilities either before, or as a complement to traditional cognitive-behavioural interventions, have the potential to maximise treatment response.</p>

scholarly journals Effect of cervical headgear on dental arch area, shape and interarch dimensions

2020 ◽  
Author(s):  
Toni Heino ◽  
Heta Kokko ◽  
Ville Vuollo ◽  
Pertti Pirttiniemi
Keyword(s):  
Standard Deviation ◽  
Early Phase ◽  
Three Dimensional ◽  
Polynomial Equation ◽  
Control Group ◽  
Dental Arch ◽  
Study Group ◽  
Class Ii Malocclusion ◽  
Angle Class Ii

Abstract Purpose The goal was to study the effects of early cervical headgear treatment on maxillary and mandibular dental arch area, shape and interarch dimensions. Methods The total study group comprised 67 children aged 7.6 years (standard deviation 0.3) with Angle class II malocclusion collected between 1992 and 1996. The children were randomly divided into two groups of equal size. In the first group, cervical headgear treatment was started immediately and undertaken for 2 years. The remaining patients served as untreated controls. Dental casts were taken and scanned at the beginning of treatment (T0) and at the 2‑year (T1) and 4‑year follow-up (T2). Three-dimensional landmarks describing the positions of maxillary and mandibular incisors, canines, first and second premolars and first molars were used to calculate and visualize the maxillary and mandibular dental arch area and shape using the polynomial equation y = Ax6 + Bx2. Results Significant changes in the shape and area of both maxillary and mandibular dental arches were induced with cervical headgear. The headgear increased dental arch area, sagittal dimensions at the mid-sagittal line and transversal dimensions at all of the measured levels in both dental arches compared to the control group. Conclusions Cervical headgear is an effective treatment device to gain space in both dental arches. Furthermore, when used as an early phase treatment, relapse is relatively small compared to the gained space.

scholarly journals The Effect of the Length and Distribution of Implants for Fixed Prosthetic Reconstructions in the Atrophic Posterior Maxilla: A Finite Element Analysis

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2556
Author(s):  
Brunilda Cenkoglu ◽  
Nilufer Balcioglu ◽  
Tayfun Ozdemir ◽  
Eitan Mijiritsky
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Minimum Principle ◽  
Three Dimensional ◽  
Surgical Techniques ◽  
Dental Arch ◽  
Element Analysis ◽  
The Maximum Principle ◽  
Posterior Maxilla ◽  
Atrophic Maxilla

In this study, different prosthetic designs that could be applied instead of advanced surgical techniques in atrophic maxilla were evaluated with finite element analysis. Atrophic posterior maxilla was modeled using computer tomography images and four models were prepared as follows: Model 1 (M1), two implants supporting a three-unit distal cantilever prosthesis; Model 2 (M2), two implants supporting a three-unit conventional fixed partial denture; Model 3 (M3), three implants supporting three connected crowns; and Model 4 (M4), two implants supporting two connected crowns. Implants 4 mm in width and 8 mm or 13 mm in length were used. A linear three-dimensional finite element programme was used for analysis. The maximum principle stress (tensile) and minimum principle stress (compressive) were used to display stress in cortical and cancellous bones. The von Mises criteria were used to evaluate the stress on the implants. M1 was found to be the most risky model. The short dental arch case (M4) revealed the lowest stresses among the models but is not recommended when one more implant can be placed because of the bending forces that could occur at the mesial implant. In M2 and M3, the distal implants were placed bicortically between the crestal and sinus cortical plates, causing a fall of the stresses because of the bicortical stability of these implants.

scholarly journals Blood derived treatment from two allogeneic sources for severe dry eye associated to keratopathy: a multicentre randomised cross over clinical trial

2019 ◽  
Vol 104 (8) ◽  
pp. 1142-1147 ◽  
Author(s):  
Emilio Campos ◽  
Piera Versura ◽  
Marina Buzzi ◽  
Luigi Fontana ◽  
Giuseppe Giannaccare ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Growth Factor ◽  
Blood Serum ◽  
Cord Blood ◽  
Dry Eye ◽  
Post Treatment ◽  
Subjective Symptoms ◽  
Treatment Change ◽  
Factor Content ◽  
Group A

AimTo compare the efficacy of cord blood and peripheral adult donor blood serum eyedrops, controlled for growth factor content, in the treatment of severe dry eye diseases (DED) resistant to conventional therapy.MethodsThis was a multicentre randomised, double-masked, cross-over clinical trial. Sixty patients diagnosed as severe DED, associated to persistent corneal epithelial defects were randomised and equally assigned to group A (treated with cord blood serum (CBS)) or group B (treated with PBS), eyedrops administered eight times/day for 1 month. Primary outcome was the pretreatment and post-treatment change in corneal fluorescein staining. Secondary outcomes included the pretreatment and post-treatment change in Ocular Surface Disease Index (OSDI) questionnaire and Visual Analogue Score (VAS) of subjective symptoms, Schirmer I test, tear break-up time and conjunctival staining. Patients with relapse in signs or symptoms after further 2 months switched to the remaining group for one additional month. Data were statistically analysed (p<0.05).ResultsCorneal staining was more significantly reduced after the CBS treatment, both VAS and OSDI score reduction was observed in both groups, but group A reported significantly less grittiness and pain. Nineteen patients shifted in the crossover period, the within individual comparison confirmed a better recovery in the CBS treatment period. Reduction in epithelial damage was positively associated with epidermal growth factor, transforming growth factorα and platelet-derived growth factor content. Levels of interleukins (IL-13) were positively associated with symptom decrease.ConclusionsOverall, DED signs improved after both CBS and PBS treatments, with potential advantages of CBS for subjective symptoms and corneal damage reduction.Clinical trial registrationNCT03064984.

The Screening and Categorization of Patients: A Case for Natural Selection?

1987 ◽  
Vol 14 (3) ◽  
pp. 181-186 ◽  
Author(s):  
N. R. E. Robertson ◽  
M. L. Jones ◽  
S. Richmond ◽  
E. May
Keyword(s):  
Measurement Techniques ◽  
Three Dimensional ◽  
Method Error ◽  
Fixed Appliance ◽  
Treatment Groups ◽  
Preliminary Study ◽  
Improved Technique ◽  
Cast Analysis ◽  
Range Of Values ◽  
Lower Arch

A preliminary study was performed on the feasibility and validity of objective categorization of patients into basic ‘treatment types’. The Reflex Metrograph was used for a three-dimensional cast analysis, and an H.P. 9874 A digitizer was used for a two-dimensional radiograph analysis. In both measurement techniques the method error was found to be acceptable. Using the Ricketts 10 Factor Analysis, it was found that by means of ‘Clinical deviators’ radiographs could be used to distinguish orthognathic cases from the other treatment groups. The three-dimensional study cast analysis showed promise, distinguishing a number of statistically significant factors within the lower arch and between simple and fixed appliance cases. A number of variables which might have been expected to be significant were confounded by their range of values within the groups. Further investigation is required with an improved technique of initial categorization of patients, perhaps by means of a panel of clinicians, and more sophisticated statistical techniques.

scholarly journals A new elastic slot system and V-wire mechanics

2017 ◽  
Vol 87 (5) ◽  
pp. 774-781 ◽  
Author(s):  
Andrea Wichelhaus
Keyword(s):  
Permanent Deformation ◽  
Biomechanical Testing ◽  
Three Dimensional ◽  
Nickel Titanium ◽  
Dental Arch ◽  
Rectangular Slot ◽  
Torque Measurements ◽  
Conventional Brackets ◽  
The Wire ◽  
The Moment

ABSTRACT Objective: To biomechanically test a new elastic slot system and V-wire mechanics. Materials and Methods: Conventional twin and self-ligating brackets and the new elastodynamic bracket were biomechanically tested. The conventional brackets had a rectangular 0.022′′ slot and the new elastodynamic bracket had a V-slot, a new slot geometry. Torque measurements were performed with 0.018′′ × 0.025′′ and 0.019′′ × 0.025′′ stainless steel (ss) archwires. A nickel-titanium V wire was used for the biomechanical measurements on the elastodynamic bracket. The measurements were done with the aid of a six-component measuring sensor. Results: The results of the biomechanical testing revealed play in the brackets with rectangular slot geometry. The V slot in the elastodynamic bracket assured that the wire fit perfectly in the slot. Dynamic moments of 5 to 10 Nmm were transmitted without any play. No permanent deformation of the slot occurred in the new elastodynamic bracket because of the elastic slot. Conclusion: Control of torque for three-dimensional positioning of the teeth in the dental arch with rectangular slot geometry as used in straight-wire therapy is difficult. If torque is bent into the wire, because of the play there is a high risk that either too much, too little, or no moment is transmitted to the teeth. The V-slot archwire/bracket geometry in conjunction with nickel titanium composition has no play and allows a reduction of forces and moments with direct and continuous transmission of torque in the bracket. Because of the elasticity of the bracket, there is an upper limit to the moment possible.

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