Prog Orthod. 2019 Jan 7;20(1):1. doi: 10.1186/s40510-018-0251-z.

ABSTRACT

OBJECTIVES: The aim of this study is to investigate and compare the characteristics of as received and retrieved NiTi archwires at a constant temperature by plotting their load/deflection graphs and quantifying three parameters describing the discharge plateau phase.

MATERIALS AND METHODS: Two hundred four NiTi archwires, traditional and heat-activated, of various cross sections, were obtained from 5 different manufacturers. Specimens prepared from the selected wires were subjected to a three-point bending test where 92 were retrieved through an in vivo retrieval protocol (crowding group C1 and group C2), 56 went through an in vitro retrieval protocol, and 56 were as received. The in vitro retrieval protocol was performed by a gear motor connected to a stainless steel support that performed fatigue cycles to the bent wires in artificial saliva. The load/deflection graphs of as received and retrieved wires were described through three parameters and the results were analyzed with classification and regression trees (CART) and analysis of variance (ANOVA).

RESULTS: Statistically significant differences between as received and retrieved wires were found only for the parameter plateau slope which represents the constancy of force expressed by the wire.

CONCLUSIONS: The aging of NiTi archwires influences the force constancy expressed. The behavior of the wires changes depending on the size, brand, and type of retrieval protocol. In terms of performance, the poorest is represented by all wires retrieved in vitro and in vivo group C2 (moderate to severe crowding).

PMID:30613836 | PMC:PMC6321830 | DOI:10.1186/s40510-018-0251-z

J Orofac Orthop. 2019 Mar;80(2):57-67. doi: 10.1007/s00056-018-00164-4. Epub 2019 Jan 4.

ABSTRACT

AIMS: Mechanical properties along the length of latest generation “multi-force” archwires were measured and compare with commercially available thermally activated and non-thermally activated nickel-titanium (NiTi) archwires.

MATERIALS AND METHODS: A modified deflection test was used to produce load/deflection curves for different positions along the lengths of a sample of 114 NiTi archwires composed by thermal NiTi, non-thermal NiTi, two types of multi-force NiTi and one type of multi-force copper archwires of various cross-sections (0.016 × 0.016 inch, 0.016 × 0.022 inch, 0.018 × 0.025 inch and 0.019 × 0.025 inch). The length, slope and mean force expressed were calculated from the resulting unloading plateaus, enabling comparison between types of archwire at different points along their lengths.

RESULTS: Among conventional thermal, conventional nonthermal and multiforce archwires, all parameters investigated were statistically different, whereby the performance of the latter was superior. Multi-force archwires displayed 27% and 31% lighter mean forces in the upper and lower arches, respectively, in addition to 62% and 40% reductions in unloading plateau slope and length, respectively, as compared to conventional CuNiTi wires. Comparison of the different types of multi-force wires tested revealed statistically significant differences in the three parameters, depending on the testing position but irrespective of their cross-section.

CONCLUSIONS: Although conventional archwires display identical behaviour along their lengths, as advertised the multi-force archwires do indeed exert a progressive force which differs between anterior, medial and posterior sections. The multi-force wires provide lighter, more prolonged and constant forces than conventional wires without cross-section-dependent variation.

PMID:30610250 | DOI:10.1007/s00056-018-00164-4

Eur J Orthod. 2019 Aug 8;41(4):434-443. doi: 10.1093/ejo/cjy076.

ABSTRACT

BACKGROUND: Low-frequency vibrations have been proposed as a means of accelerating tooth movement and reducing orthodontic treatment times.

OBJECTIVE: To determine any differences in the accuracy of dental movement in patients treated with a low-frequency vibration aligner protocol and/or by reducing the aligner replacement interval with respect to a conventional protocol.

DESIGN: This trial was designed as a single-centre, randomized controlled clinical trial.

METHODS: Participants: Patients (aged 27.1 ± 9.0 years) who required orthodontic treatment with aligners. Randomization: Patients were randomly allocated to three arms as determined by a computer-randomization scheme. Group A were assigned a conventional protocol (aligners replaced every 14 days); group B also used a low-frequency vibration device for 20 minutes per day; group C followed the same vibration protocol but replaced their aligners every 7 days. Blinding: The operator who performed the set-up and the one who analysed the data were blinded to the group of the patients. Outcome: Pre- and post-treatment digital models were analysed using VAM software to identify the accuracy/imprecision of dental movements. One-way analysis of variance (P < 0.05) and the Bonferroni post hoc test were used to identify any statistically significant differences between the three arms in terms of the accuracy of tooth movement versus the prescription.

RESULTS: Numbers analysed: A total of 45 patients (15 for group) were analysed (i.e. 2286 dental movements). Outcome: No statistically significant differences emerged between groups A and C in the upper arch, or among groups A, B, and C in the lower. Group B displayed significantly greater accuracy with respect to group A in upper incisor rotation (P = 0.016), and to group C in vestibulolingual (P = 0.007) and mesiodistal tipping (P = 0.029) of the upper canines, and vestibulolingual tipping of the upper molars (P = 0.0001). Harms: No adverse events or side-effects were registered.

CONCLUSIONS: Considering all tooth and movement types of the 45 participants, the mean total imprecision was 2.1 ± 0.9 degrees, with respect to a mean prescription of 5.7 ± 2.2 degrees. There was no difference in accuracy between replacing the aligners accompanied by low-frequency vibration every 7 days and replacing them every 14 days without vibration. Moreover, low-frequency vibration seemed to improve the accuracy of a conventional protocol in terms of upper incisor rotation.

TRIAL REGISTRATION: The German Clinical Trials Register (DRK00015613).

PMID:30423130 | DOI:10.1093/ejo/cjy076

Acta Otorhinolaryngol Ital. 2020 Feb;40(1):50-56. doi: 10.14639/0392-100X-2290. Epub 2019 Sep 30.

NO ABSTRACT

PMID:31570902 | PMC:PMC7147537 | DOI:10.14639/0392-100X-2290

Nanomaterials (Basel). 2019 Jul 12;9(7):1010. doi: 10.3390/nano9071010.

ABSTRACT

The analysis of forces, moments and pressure points has long been of great interest in orthodontics. Hence, we set out to define a method for measuring the pressure exerted by aligners on the teeth, and specifically to identify the precise points of pressure exertion. Intraoral scans were performed on a patient with optimal alignment and levelling before and after 2º vestibularisation of the upper central incisor. Pressure sensor film was placed in a dedicated housing between the aligner and teeth in order to record the pressure exerted after 15 s of aligner application. The images captured by the film were scanned, digitised, and subsequently analysed. Areas and amounts of pressure generated by the aligners were evaluated, and the net force of each was calculated, adjusted to take into consideration passive values. The method revealed the areas of contact by which the aligner transmits force on the teeth, and the pressures at which it does so. The pressure exerted by an aligner is not evenly distributed across the entire surface of the tooth during lingual tipping of an upper incisor. The areas of force concentration were not identical, as these are influenced by factors resulting from the manufacturing and casting processes.

PMID:31336979 | PMC:PMC6669747 | DOI:10.3390/nano9071010

Int Orthod. 2019 Jun;17(2):365-374. doi: 10.1016/j.ortho.2019.03.019. Epub 2019 Apr 22.

ABSTRACT

This case report discussed a combined surgical-orthodontic rescue of two impacted teeth in a large dentigerous cyst by the means of fixed orthodontic appliances. After careful evaluation of the 3D radiographic exams, extraction of the deciduous elements was carried out, followed by marsupialization and orthodontic traction of the impacted teeth. Surgical procedures, pre- and posttreatment records and orthodontic biomechanical evaluations are discussed.

PMID:31023587 | DOI:10.1016/j.ortho.2019.03.019

J Oral Facial Pain Headache. 2019 Spring;33(2):199-204. doi: 10.11607/ofph.2081.

ABSTRACT

AIMS: To assess the correlation between tooth wear and sleep-time masseter muscle activity (sMMA) in a group of healthy young adults who underwent home electromyographic/electrocardiographic (EMG/ECG) recordings with a portable device.

METHODS: A total of 41 healthy volunteers (23 women, 18 men; mean age 28.8 years, range 25 to 40) with good natural dentition underwent a 2-night in-home evaluation with a portable device that allowed a simultaneous sleep-time recording of EMG signals from both masseter muscles and heart rate. The number of sleep bruxism (SB) episodes per sleep hour (SB index), the number of phasic, tonic, and mixed sMMA events per hour, and the total number of sMMA events per night were calculated. All individuals also underwent an assessment of tooth wear on digital casts with the adoption of a six-degree rating scale. Correlations between sMMA variables and tooth wear were assessed using Pearson test. The null hypothesis was that correlation between the two conditions would not be significant.

RESULTS: On average, the SB index was 4.5 ± 2.6, while the total number of sleep-time masseter contractions was 97.2 ± 55.2. Of those contractions, almost 60% were phasic. Average tooth wear was 1.5 ± 0.7, with the canines and mandibular incisors showing the highest wear scores. For all pairwise analyses, correlation values were not significant (P values .11 to .69), with r values ranging from 0.064 to 0.253.

CONCLUSION: The null hypothesis of an absence of correlation between tooth wear and sMMA could not be rejected, implying that tooth wear cannot be used as an indicator of ongoing SB or sMMA. Future studies taking into account the multifaceted nature of tooth wear and the complex natural course of sleep phenomena are encouraged to investigate the issue further, at the individual level.

PMID:31013339 | DOI:10.11607/ofph.2081

Cranio. 2021 Mar;39(2):113-118. doi: 10.1080/08869634.2019.1587854. Epub 2019 Mar 25.

ABSTRACT

Objective: To assess the association between self-reported awake bruxism (AB) and the chronotype profile among Brazilian, Portuguese, and Italian dental students.Methods: A cross-sectional study involving 205 dental students was developed. Self-reported AB as well as information on sleep characteristics were collected from a questionnaire. The Morningness-Eveningness Questionnaire (MEQ) was used to measure the chronotype profile. Descriptive statistical analysis, the chi-square test, and univariate analysis were used to evaluate the factors associated with AB.Results: The prevalence of AB in all groups was 33.7%. The intermediate chronotype profile was the most prevalent (60.4%), and only 16.7% of the participants had the morning profile. The univariate analysis showed that older dental students (OR = 2.640, 95% CI 1.388-5.021) and those with the eveningness chronotype profile (OR = 3.370, 95% CI 1.302-8.725) are associated with AB.Discussion: Students over the age of 22 and those with the eveningness chronotype profile were prone to AB.

PMID:30907703 | DOI:10.1080/08869634.2019.1587854

J Clin Orthod. 2019;53(9):508-517.

NO ABSTRACT

PMID:32053497

Am J Orthod Dentofacial Orthop. 2020 Feb;157(2):218-227. doi: 10.1016/j.ajodo.2019.03.024.

ABSTRACT

INTRODUCTION: The aim of this study was to investigate the vestibular anatomy of teeth in samples of adult Italian and Mozambican subjects in ideal occlusion and permanent dentition and identify any anatomic characteristics that may influence bonding in the straight-wire technique.

METHODS: Linear measurements and coordinates of each curve representing the clinical crown height and width of each tooth were acquired from digital models of each subject categorized to 1 of 2 groups: Italian (18 males, 22 females; mean age, 29.6 ± 5.7 years) or Mozambican (14 males, 15 females; mean age, 23.4 ± 5.9 years). All subjects had normal dentition and no previous orthodontic treatment, fillings, or prostheses. Method error and systematic error were calculated according to the Dahlberg formula (S2 = ∑ d2/2n) and dependent Student t test (P <0.05), respectively. Tooth symmetry was investigated through a paired-samples t test (P <0.05) and sex difference via an independent-samples t test (P <0.05). After neither asymmetry nor sexual dimorphism was found, all data were pooled, inverting the signs of the X coordinates and then mirroring data. Subsequently, a 2-samples t test (P <0.05) and a multivariate cluster analysis were performed on the mirrored data to compare the 2 groups and to identify any within-group diversity for number of clusters for each tooth. Means of all linear measurements and coordinates (crown height and width) calculated for each cluster were reported and compared using a standard 2-samples t test (P <0.05).

RESULTS: Two clusters were identified for the maxillary second premolars and molars in Italian subjects, whereas in the Mozambican subjects, there were 2 clusters for the maxillary first premolars and lateral incisors and 3 clusters for the maxillary canines and central incisors. The mandibular arch was remarkably homogeneous, with only 1 cluster per tooth in each group. In the mandibular arch, statistical differences were recorded between ethnic groups in crown height at the central incisors and second molars and in crown width in the sector from the second premolar to the second molar.

CONCLUSIONS: There were considerable differences both between and within racial groups in crown height, crown width, and numbers of clusters, which should be taken into account during bonding. Although single-bracket placement guides specific for ethnicity may be feasible for the mandibular arch, the significant diversity in number of clusters in the maxillary arch indicates that more accurate bracket placement guides that take into account such heterogeneity are required.

PMID:32005474 | DOI:10.1016/j.ajodo.2019.03.024