Comparative study of 2 software programs for predicting profile changes in Class III patients having double-jaw orthognathic surgery

Introduction: Computer software can be used to predict orthognathic surgery outcomes. The aim of this study was to subjectively compare the soft-tissue surgical simulations of 2 software programs. Methods: Standard profile pictures were taken of 10 patients with a Class III malocclusion and a concave facial profile who were scheduled for double-jaw orthognathic surgery. The patients had horizontal maxillary deficiency or horizontal mandibular excess. Two software programs (Dentofacial Planner Plus [Dentofacial Software, Toronto, Ontario, Canada] and Dolphin Imaging [version 9.0, Dolphin Imaging Software, Canoga Park, Calif]) were used to predict the postsurgical profiles. The predictive images were compared with the actual final photographs. One hundred one orthodontists, oral-maxillofacial surgeons, and general dentists evaluated the images and were asked whether they would use either software program to plan treatment for, or to educate, their patients. Results: Statistical analyses showed differences between the groups when each point was judged. Dolphin Imaging software had better prediction of nasal tip, chin, and submandibular area. Dentofacial Planner Plus software was better in predicting nasolabial angle, and upper and lower lips. The total profile comparison showed no statistical difference between the softwares. Conclusions: The 2 types of software are similar for obtaining 2-dimensional predictive profile images of patients with Class III malocclusion treated with orthognathic surgery. (Am J Orthod Dentofacial Orthop 2010; 137: 452.e1-452.e5)

Correlation between morphology and function of the upper lip: a longitudinal evaluation

In order to evaluate the relationship between the morphology of the upper lip and muscle activity in a sample of 38 subjects (17 males and 21 females) with Angle Class II division 1 malocclusions, cephalometric and electromyographic analyses were conducted. The sample was subdivided into either predominantly nose or mouth breathers. The individuals were evaluated at two different periods, with a 2 year interval. At the first observation, the subjects were 11 years to 14 years 11 months of age and at the second observation, 13 years 4 months to 16 years 6 months of age. Height and thickness of the upper lip were measured on lateral cephalograms with the aid of a digital pachymeter. For each individual, electromyographic records were obtained of the orbicularis oris superior muscle at rest and in a series of 12 movements. The electromyographic data were normalized as a function of amplitude, for achievement of the percentage value of each movement. Pearson and Spearman correlation tests were applied.The results showed some correlation between morphology and muscle function (at a confidence level of 95 per cent). However, as the values of the correlation coefficient (r) were too low to establish associations between variables, it was concluded that the dimensions of the upper lip are not correlated with muscle activity.

Cephalometric Evaluation of Pharyngeal Airway Space Changes in Class III Patients Undergoing Orthognathic Surgery

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Treatment effects produced by the Bionator appliance. Comparison with an untreated Class II sample

The purpose of this retrospective investigation was to evaluate the dentoalveolar and skeletal cephalometric changes of the Bionator appliance on individuals with a Class II division 1 malocclusion. Lateral cephalograms of 44 patients were divided into two equal groups. The control group comprised 22 untreated Class II children (11 males, 11 females), with an initial mean age of 8 years 7 months who were followed without treatment for a period of 13 months. The Bionator group (111 males, 11 females) had an initial mean age of 10 years 8 months, and were treated for a mean period of 16 months. Lateral cephalometric headfilms were obtained of each patient and control at the beginning and end of treatment.The results showed that there were no changes in forward growth of the maxilla in the experimental group compared with the control group. However, the Bionator treatment produced a statistically significant increase in mandibular protrusion, and in total mandibular and body lengths. There were no statistically significant differences in craniofacial growth direction between the Bionator group and the control group, although the treated patients demonstrated a greater increase in posterior face height. The Bionator appliance produced labial tipping of the lower incisors and lingual inclination of the upper incisors, as well as a significant increase (P < 0.01) in mandibular posterior dentoalveolar height. The major effects of the Bionator appliance were dentoalveolar, with a smaller significant skeletal effect. The results indicate that the correction of a Class II division 1 malocclusion with the Bionator appliance is achieved not only by a combination of mandibular skeletal effects, but also by significant dentoalveolar changes.

Comparative study of the Frankel (FR-2) and bionator appliances in the treatment of Class II malocclusion

The purpose of this investigation was to compare the dentoalveolar and skeletal cephalometric changes produced by the Frankel (FR-2) and bionator appliances in persons with Class 11 malocclusion. Lateral cephalograms were available for 66 patients of both sexes, who were divided into 3 groups of 22. The control group included untreated Class 11 children, with an initial mean age of 8 years 7 months; they were followed without treatment for 13 months. The FR-2 appliance group had an initial mean age of 9 years; those children were treated for a mean period of 17 months. The bionator group initially had a mean age of 10 years 8 months; on average, they were treated for 16 months. The results demonstrated no significant changes in maxillary growth during the evaluation period. Both appliances showed statistically significant increases in mandibular growth and mandibular protrusion, with greater increases in patients treated in the bionator group. Both experimental groups showed an improvement in the maxillomandibular relationship. There were no significant changes in growth direction, while the bionator group had a greater increase in posterior facial height. Both appliances produced similar labial tipping and protrusion of the lower incisors, lingual inclination, retrusion of the upper incisors, and a significant increase in mandibular posterior dentoalveolar height. The major treatment effects of bionator and FR-2 appliances were dentoalveolar, with a smaller, but significant, skeletal effect.

On the limit cycles of a class of piecewise linear differential systems in R-4 with two zones

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Treatment Effects Produced by Fränkel Appliance in Patients with Class II, Division 1 Malocclusion

The purpose of this investigation was to evaluate the dentoalveolar and skeletal cephalometric changes produced by the Fränkel appliance in individuals with a Class II, division 1 malocclusion. Lateral cephalograms of 44 patients of both sexes were divided in two groups of 22 each. The control group was comprised of untreated Class II children with an initial mean age of eight years and seven months who were followed without treatment for a period of 13 months. The Fränkel group had an initial mean age of nine years and was treated for a mean period of 17 months. Lateral cephalometric headfilms of each patient were obtained at the beginning and end of treatment. The Fränkel appliance produced no significant changes in maxillary growth during the evaluation period, while a statistically significant increase in mandibular length was observed. The maxillomandibular relationship improved mostly because of an increase in mandibular length. In addition, there were no statistically significant differences in the craniofacial growth direction between the Fränkel and the control group, both showing a slight downward rotation of the palatal plane. The Fränkel appliance produced a labial tipping of the lower incisors and a lingual inclination of the upper incisors as well as a significant increase in mandibular posterior dentoalveolar height. It was concluded that the main effects of the Fränkel appliance during this time period were mostly dentoalveolar with a smaller but significant skeletal mandibular effect.

Electromyographic evaluation of the upper lip according to the breathing mode: A longitudinal study

The present study aimed at analyzing and comparing longitudinally the EMG (electromyographic activity) of the superior orbicularis oris muscle according to the breathing mode. The sample, 38 adolescents with Angle Class II Division 1 malocclusion with predominantly nose (PNB) or mouth (PMB) breathing, was evaluated at two different periods, with a two-year interval between them. For that purpose, a 16-channel electromyography machine was employed, which was properly calibrated in a PC equipped with an analogue-digital converter, with utilization of surface, passive and bipolar electrodes. The RMS data (root mean square) were collected at rest and in 12 movements and normalized according to time and amplitude, by the peak value of EMG, in order to allow comparisons between subjects and between periods. Comparison of the muscle function of PNB and PMB subjects at period 1 (P1), period 2 (P2) and the variation between periods (Δ) did not reveal statistically significant differences between groups (p < 0.05). However, longitudinal evaluation of the muscle function in PNB and PMB subjects demonstrated different evolutions in the percentage of required EMG for accomplishment of the movements investigated. It was possible to conclude that there are differences in the percentage of electric activity of the upper lip with the growth of the subjects according to the breathing mode.

Influence of the construction bite vertical and horizontal dimensions on dentoskeletal structures induced by the Klammt appliance in Class II treatment

Aim: To evaluate the influence of construction bite in the dentoskeletal changes induced by Klammt Appliance. Methods: The sample consisted of 17 children, with Class II malocclusion and initial mean age of 8.5 years. The construction bite was obtained using an Exactobite on edge-toedge anteroposterior relationship with 3 mm interincisal clearance. The height of the acrylic was determined by initial overbite associated to interincisal clearance and measured with digital caliper. The amount of advancement was obtained and measured by initial overjet in the lateral radiography. Pearson's correlation, linear regression and ANOVA were used to determine the relationship between dentoskeletal and construction bite variables. Results: The increase in the height of the acrylic promotes a greater inhibition of the forward displacement of the nasal spine and reduction in the facial growth index. The increase in the mandibular advancement induces more downward displacement of nasal spine and pogonion; a counter-clockwise rotation of palatine plane; an increase in mandibular length, maxillary alveolar height and interincisal angle; a decrease in mandibular alveolar height, the intermaxillary discrepancy and overjet; and palatal tipping of upper incisors. Conclusions: The different dimensions of the construction bite influence the dentoskeletal changes induced by the appliance in Class II treatment.

Post-sphaleron baryogenesis and an upper limit on the neutron-antineutron oscillation time

A recently proposed scenario for baryogenesis, called post-sphaleron baryogenesis (PSB), is discussed within a class of quark-lepton unified framework based on the gauge symmetry SU(2)L×SU(2) R×SU(4)c realized in the multi-TeV scale. The baryon asymmetry of the Universe in this model is produced below the electroweak phase transition temperature after the sphalerons have decoupled from the Hubble expansion. These models embed naturally the seesaw mechanism for neutrino masses and predict color-sextet scalar particles in the TeV range which may be accessible to the LHC experiments. A necessary consequence of this scenario is the baryon-number-violating ΔB=2 process of neutron-antineutron (n-n̄) oscillations. In this paper we show that the constraints of PSB, when combined with the neutrino oscillation data and restrictions from flavor changing neutral currents mediated by the colored scalars, imply an upper limit on the n-n̄ oscillation time of 5×1010 sec regardless of the quark-lepton unification scale. If this scale is relatively low, in the (200-250) TeV range, τn-n̄ is predicted to be less than 1010 sec, which is accessible to the next generation of proposed experiments. © 2013 American Physical Society.

Class II malocclusion treatment using high-pull headgear with a splint: a systematic review

Objective: To systematically review the scientific evidence pertaining to the effectiveness of high-pull headgear in growing Class II subjects. Methods: A literature survey was performed by electronic database search. The survey covered the period from January 1966 to December 2008 and used Medical Subject Headings (MeSH). Articles were initially selected based on their titles and abstracts; the full articles were then retrieved. The inclusion criteria included growing subjects between 8 to 15 years of age, Class II malocclusion treatment with high-pull headgear, and a control group with Class II malocclusion. References from selected articles were hand-searched for additional publications. Selected studies were evaluated methodologically. Results: Four articles were selected; none were randomized controlled trials. All of the articles clearly formulated their objectives and used appropriate measures. The studies showed that high-pull headgear treatment improves skeletal and dental relationship, distal displacement of the maxilla, vertical eruption control and upper molars distalization. One of the studies showed a slight clockwise rotation of the palatal plane; the others showed no significant treatment effect. The mandible was not affected by the treatment. Conclusion: While there is still a lack of strong evidence demonstrating the effects of high-pull headgear with a splint, other studies indicate that the AP relations improve due to distalization of the maxilla and upper molars, with little or no treatment effects in the mandible. Greater attention to the design should be given to improve the quality of such trials. © 2013 Dental Press Journal of Orthodontics.

Assessment of first molars sagittal and rotational position in Class II, division 1 malocclusion

OBJECTIVE: This study assessed the anterior-posterior positioning of the upper and lower first molars, and the degree of rotation of the upper first molars in individuals with Class II, division 1, malocclusion. METHODS: Asymmetry I, an accurate device, was used to assess sixty sets of dental casts from 27 females and 33 males, aged between 12 and 21 years old, with bilateral Class II, division 1. The sagittal position of the molars was determined by positioning the casts onto the device, considering the midpalatal suture as a symmetry reference, and then measuring the distance between the mesial marginal ridge of the most distal molar and the mesial marginal ridge of its counterpart. With regard to the degree of rotation of the upper molar, the distance between landmarks on the mesial marginal ridge was measured. Chi-square test with a 5% significance level was used to verify the variation in molars position. Student's t test at 5% significance was used for statistical analysis. RESULTS: A great number of lower molars mesially positioned was registered, and the comparison between the right and left sides also demonstrated a higher number of mesially positioned molars on the right side of both arches. The average rotation of the molars was found to be 0.76 mm and 0.93 mm for the right and left sides, respectively. CONCLUSION: No statistically significant difference was detected between the mean values of molars mesialization regardless of the side and arch. Molars rotation, measured in millimeters, represented ¼ of Class II.

Impact of Quantity of Resin, C-factor, and Geometry on Resin Composite Polymerization Shrinkage Stress in Class V Restorations

Objective: This study evaluated the effect of quantity of resin composite, C-factor, and geometry in Class V restorations on shrinkage stress after bulk fill insertion of resin using two-dimensional finite element analysis.Methods: An image of a buccolingual longitudinal plane in the middle of an upper first premolar and supporting tissues was used for modeling 10 groups: cylindrical cavity, erosion, and abfraction lesions with the same C-factor (1.57), a second cylindrical cavity and abfraction lesion with the same quantity of resin (QR) as the erosion lesion, and then all repeated with a bevel on the occlusal cavosurface angle. The 10 groups were imported into Ansys 13.0 for two-dimensional finite element analysis. The mesh was built with 30,000 triangle and square elements of 0.1 mm in length for all the models. All materials were considered isotropic, homogeneous, elastic, and linear, and the resin composite shrinkage was simulated by thermal analogy. The maximum principal (MPS) and von Mises stresses (VMS) were analyzed for comparing the behavior of the groups.Results: Different values of angles for the cavosurface margin in enamel and dentin were obtained for all groups and the higher the angle, the lower the stress concentration. When the groups with the same C-factor and QR were compared, the erosion shape cavity showed the highest MPS and VMS values, and abfraction shape, the lowest. A cavosurface bevel decreased the stress values on the occlusal margin. The geometry factor overcame the effects of C-factor and QR in some situations.Conclusion: Within the limitations of the current methodology, it is possible to conclude that the combination of all variables studied influences the stress, but the geometry is the most important factor to be considered by the operator.

Three-dimensional dental arch changes of patients submitted to orthodontic-surgical treatment for correction of Class II malocclusion

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)