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Three-dimensional assessment of teeth first-, second- and third-order position in Caucasian and African subjects with ideal occlusion

Prog Orthod. 2015;16:11. doi: 10.1186/s40510-015-0086-9. Epub 2015 May 26.


BACKGROUND: The aim of this study was to provide an updated version of Andrews’ seminal study by exploiting 3D software to analyse the tip, torque and in-out values of two groups of different racial and ethnic background.

METHODS: The analysis was conducted on one Caucasian group (30 individuals) and one of African origin (29). All subjects were adult, in normal occlusion and had no previous history of orthodontic treatment. Rhinoceros™ 3D modelling software was used to identify anatomical reference points, planes and axes and to make the appropriate measurements.

RESULTS: Compared to Andrews’ measurements, we found more positive coronal tip values in both African and Caucasian subjects, while the torque values we measured tended to be less negative in the posterior sectors than those reported by Andrews. We measured greater tip values in the lower jaw of Caucasian with respect to African subjects, particularly in the middle sectors.

CONCLUSIONS: Race and ethnicity have a strong influence on values of tip, torque and in-out. This is translated as a more positive tip in Caucasian subjects and a more positive torque in those of African descent (greater proclination of the incisors). Finally, with respect to the values reported by Andrews, we found a tendency to more positive mean tip (except for at the upper second molars and lower incisors) and less negative torque in the posterior sectors.

PMID:26061990 | PMC:PMC4442781 | DOI:10.1186/s40510-015-0086-9

Three-dimensional assessment of teeth first-, second- and third-order position in Caucasian and African subjects with ideal occlusion2022-11-06T17:18:49+00:00

Temporomandibular Joint Disorders in Patients With Different Facial Morphology. A Systematic Review of the Literature

J Oral Maxillofac Surg. 2016 Jan;74(1):29-46. doi: 10.1016/j.joms.2015.07.006. Epub 2015 Jul 18.


PURPOSE: The present article aimed to review systematically the literature on the relation between facial skeletal structures and temporomandibular joint (TMJ) disorders.

MATERIALS AND METHODS: A systematic search in the dental and medical literature was performed to identify all studies of humans assessing the relation between TMJ disorders and facial morphology. Articles were included based on study design, irrespective of TMJ disorder (eg, disc displacement, osteoarthrosis, or unspecified), skeletal features, diagnostic strategies (e.g., imaging techniques or clinical assessment), and population (eg, demographic features of participants) under investigation. The selected articles were assessed according to a format based on patients, problem, and population, intervention, comparison, and outcome and quality was evaluated based on the Newcastle-Ottawa Scale.

RESULTS: Thirty-four articles were included in the review, 27 of which concerned adult samples and 7 concerned adolescent samples. Quality was generally moderate. The articles dealt with the relation between facial morphology and the following TMJ disorders, assessed clinically or by magnetic resonance (MR): disc displacement (n = 20), osteoarthritis or osteoarthrosis (n = 8), and temporomandibular disorder signs and symptoms (n = 6). The different approaches featuring the various investigations and the presence of some potential methodologic biases complicated a summary of the findings. Most studies reported that some features related to the vertical dimension of the face might help distinguish patients with potential TMJ disc displacement or MR-detected signs of osteoarthrosis from those without TMJ disorders.

CONCLUSIONS: The quality of the available literature is not adequate to provide an evidence base on the topic. Despite the heterogeneity of design and findings of the reviewed articles, it seems reasonable to suggest that skeletal Class II profiles and hyperdivergent growth patterns are likely associated with an increased frequency of TMJ disc displacement and degenerative disorders.

PMID:26255097 | DOI:10.1016/j.joms.2015.07.006

Temporomandibular Joint Disorders in Patients With Different Facial Morphology. A Systematic Review of the Literature2022-11-06T17:18:49+00:00

Orthodontics is temporomandibular disorder-neutral

Angle Orthod. 2016 Jul;86(4):649-54. doi: 10.2319/051015-318.1. Epub 2015 Oct 29.


OBJECTIVES: To assess if subjects with a clinical diagnosis of temporomandibular disorders (TMDs) have a similar prevalence of orthodontic history as a population of TMD-free individuals and to assess if those subjects who have a history of ideal orthodontics have fewer symptoms than those with a history of nonideal orthodontics.

MATERIALS AND METHODS: Two groups of age- and sex-matched individuals belonging to either a study (“TMD”) or a control group were recruited. Subjects who underwent orthodontic treatment were classified as having a history of ideal or nonideal orthodontics based on the current presence of normal values in five reference occlusal features.

RESULTS: The correlation with a history of orthodontic treatment was not clinically significant for any of the TMD diagnoses (ie, muscle pain, joint pain, disc displacement, arthrosis), with Phi (Φ) coefficient values within the -0.120 to 0.058 range. Within the subset of patients with a history of orthodontics, the correlation of ideal or nonideal orthodontic treatment with TMD diagnoses was, in general, not clinically relevant or was weakly relevant.

CONCLUSIONS: Findings confirmed the substantial absence of clinically significant effects of orthodontics as far as TMD is concerned. The very low correlation values of a negative or positive history of ideal or nonideal orthodontics with the different TMD diagnoses suggest that orthodontic treatment could not have a true role for TMD.

PMID:26512757 | PMC:PMC8601478 | DOI:10.2319/051015-318.1

Orthodontics is temporomandibular disorder-neutral2022-11-06T17:18:48+00:00

Comparison of dental and alveolar arch forms between different ethnic groups

Int Orthod. 2015 Dec;13(4):462-88. doi: 10.1016/j.ortho.2015.09.013. Epub 2015 Nov 4.


OBJECTIVE: The aims of this study were to evaluate, by means of 3D software, any correlation between ethnic group and the shape and size of the dental arcade and its bony support, and to investigate the correspondence between the latter two variables within each ethnic group. The data gathered were also compared with the measurements of commercially available pre-formed archwires to determine which provide the best fit for each arch in each group.

MATERIALS AND METHODS: The shape and size of the dental and alveolar arches of 29 subjects of African origin and 37 Caucasian subjects were compared in terms of linear inter-canine, inter-premolar and inter-molar measurements, overall arch length, and the distance between each tooth and the reference occlusal plane. To determine which pre-formed archwires are best suited to each of the two ethnic groups, the in-out of the brackets was considered, simulating their presence in the oral cavity.

RESULTS: The upper and lower dental and alveolar arches were all wider and longer in African with respect to Caucasian subjects (P<0.05). In general, “Roth small” (index value 1.556) and “Ideal Form Medium” (index value 0.645) archwires were better suited to both upper and lower arcades in the latter group, while “Damon” (index value 1.447) and “Ideal Form Large” (index value 1.695) conformed better to the size and shape of both arcades in the former.

CONCLUSIONS: There are very significant differences in arch form between the two ethnic groups considered, and the range of pre-formed archwires on the market does not provide for the anatomical variability of patients.

PMID:26545346 | DOI:10.1016/j.ortho.2015.09.013

Comparison of dental and alveolar arch forms between different ethnic groups2022-11-06T17:18:48+00:00

Optical properties of orthodontic aligners–spectrophotometry analysis of three types before and after aging

Prog Orthod. 2015;16:41. doi: 10.1186/s40510-015-0111-z. Epub 2015 Nov 18.


BACKGROUND: The aim was to assess and compare absorbance and transmittance values of three types of clear orthodontic aligners before and after two cycles of in vitro aging.

METHODS: Nine samples of orthodontic aligners from three different manufacturers (Invisalign, Align Technology, Santa Clara, CA, USA; All-In, Micerium, Avegno, GE, Italy; F22 Aligner, Sweden & Martina, Due Carrare, PD, Italy) were selected, and each sample was subjected to spectrophotometry analysis of both its transmittance and absorbance a total of 27 times. Samples were subsequently aged in vitro at a constant temperature in artificial saliva supplemented with food colouring for two cycles of 14 days each. The spectrophotometry protocol was then repeated, and the resulting data were analysed and compared by means of ANOVA (p < 0.05).

RESULTS: All types of aligners tested yielded lower transmittance and higher absorbance values after aging, but the difference was not significant in any case. That being said, the F22 aligners were found to be most transparent, both before and after aging, followed by Invisalign and All-In, and these differences were statistically significant.

CONCLUSIONS: Commercial aligners possess significantly different optical, and therefore aesthetic, properties, both as delivered and following aging.

PMID:26582007 | PMC:PMC4651973 | DOI:10.1186/s40510-015-0111-z

Optical properties of orthodontic aligners–spectrophotometry analysis of three types before and after aging2022-11-06T17:18:48+00:00

New Technologies for Insect-Resistant and Herbicide-Tolerant Plants

Trends Biotechnol. 2016 Jan;34(1):49-57. doi: 10.1016/j.tibtech.2015.10.006. Epub 2015 Nov 24.


The advent of modern molecular biology and recombinant DNA technology has resulted in a dramatic increase in the number of insect-resistant (IR) and herbicide-tolerant (HT) plant varieties, with great economic benefits for farmers. Nevertheless, the high selection pressure generated by control strategies for weed and insect populations has led to the evolution of herbicide and pesticide resistance. In the short term, the development of new techniques or the improvement of existing ones will provide further instruments to counter the appearance of resistant weeds and insects and to reduce the use of agrochemicals. In this review, we examine some of the most promising new technologies for developing IR and HT plants, such as genome editing and antisense technologies.

PMID:26620971 | DOI:10.1016/j.tibtech.2015.10.006

New Technologies for Insect-Resistant and Herbicide-Tolerant Plants2022-11-06T17:18:48+00:00

Load deflection characteristics of square and rectangular archwires

Int Orthod. 2016 Mar;14(1):1-14. doi: 10.1016/j.ortho.2015.12.011. Epub 2016 Jan 27.


AIMS: To determine and compare the relative stiffness of a large selection of commonly-used square and rectangular steel, super-tempered steel, NiTi, and TMA orthodontic archwires of various cross-sections, in order to provide the clinician with a useful, easy-to-consult guide to archwire sequence selection.

MATERIALS AND METHODS: Twenty-four archwires of different cross-section shape, size and material were selected. Each type was subjected to a modified three-point bending test, performed in triplicate using an Instron 4467 dynamometer. Each sample was deflected by 1mm, and the corresponding load recorded. The relative stiffness of each archwire sample was calculated, and samples were compared by material and by cross-section.

RESULTS: A considerable difference in resistance to deflection was revealed between all the tested archwires. As expected, the resistance to deflection of archwires of the same cross-section was found to increase with increasing stiffness of their construction material. Specifically, steel archwires can be as much as 8 times stiffer than NiTi archwires of the same shape and cross-section, and super-tempered steel archwires are invariably stiffer than traditional steel versions. Marked differences in resistance to deflection were also found between NiTi archwires made of the same material but with different shape characteristics.

CONCLUSIONS: In archwires of the same cross-section, steel is always stiffer than TMA and NiTi, and super-tempered steel is always stiffer than conventional steels. In archwires of the same material, the stiffness increases with the cross-section, in particular with its height.

PMID:26826971 | DOI:10.1016/j.ortho.2015.12.011

Load deflection characteristics of square and rectangular archwires2022-11-06T17:18:48+00:00

Caries prevention during orthodontic treatment: In-vivo assessment of high-fluoride varnish to prevent white spot lesions

Am J Orthod Dentofacial Orthop. 2016 Feb;149(2):238-43. doi: 10.1016/j.ajodo.2015.07.039.


INTRODUCTION: Our objective was to evaluate the efficacy of a fluoridated varnish in preventing white spot lesions in patients with fixed appliances. A laser-induced fluorescence device was used to determine any correlations between the degree of demineralization and the length of the observation period, the arch sector, the frequency of varnish application, and the specific tooth site.

METHODS: A split-mouth study design was used for 24 orthodontic patients, allocated randomly to 2 subgroups with differing frequencies of Duraphat varnish (Colgate-Palmolive, New York, NY) application. Repeated measures of the degree of demineralization were taken on the vestibular surfaces of 12 teeth (6 varnished and 6 unvarnished controls). Measurements were taken at 4 sites using a DIAGNOdent Pen 2190 laser (KaVo, Biberach an der Riss, Germany) and then subjected to statistical analysis.

RESULTS: Generalized linear model and coefficient model analysis showed differences in the degrees of demineralization between treated and untreated teeth, but this was not statistically significant in terms of time point, frequency of application, or specific tooth site. However, when we analyzed the position of the teeth, the varnished anterior teeth showed a statistically significant reduction in demineralization compared with their unvarnished counterparts.

CONCLUSIONS: Periodic application of fluoride varnish can offer some protection against white spots, but not to a statistically significant degree if the patients have excellent oral hygiene.

PMID:26827980 | DOI:10.1016/j.ajodo.2015.07.039

Caries prevention during orthodontic treatment: In-vivo assessment of high-fluoride varnish to prevent white spot lesions2022-11-06T17:18:47+00:00