v. 17, no. 3
Dental Press Journal of Orthodontics – ISSN 2176-9451
Dental Press J. Orthod.
v. 17, no. 3
May / June
The statistics of a clinical case
Some interesting discussions have been observed, in social networking, what is preached as an excessive appreciation of researchers for statistical analysis, in lieu of clinical experience. As a clinician and researcher with some learning in statistics, I believe it is a mistake to separate the two issues.
Recently, a 14 year-old patient who came to me for orthodontic retreatment, presented in the routine radiographic records a radiolucent image with clear borders and approximately 1 cm in diameter. Immediately I asked for a pathologist evaluation, who, facing an imminent suspect of idiopathic bone cavity, or traumatic bone cyst, recommended a biopsy. The histological examination confirmed the diagnostic hypothesis. It was indeed a cyst. Her mother said that the remote probability of a neoplasia brought concern to friends and family. She had heard a similar story from a friend whose teenage daughter also would have used braces. The mother?s logic had caused the following inference:
?- So, Doctor... I think the use of these appliances is causing these injuries. Look, two teenagers and these images were detected in both.?
I explained to the mother that, despite the logical observation, we cannot prove this cause-effect relationship imagined, only with the data reported. That?s because she should take into consideration that it is normal for all patients who wear braces to take X-rays often and therefore it is more likely to detect such findings in subjects who underwent orthodontic treatment ? simply because they take more X-rays. The X-ray, in turn, facilitates the discovery of a bone injury, a fact already reported.1 Orthodontic treatment seems to be, moreover, a confounding factor and at least for now, science is lacking in well designed studies on this relationship.
The situation described above illustrates how the human mind is set to find the order, even where there is none. Our mind was built to identify a definite cause for every event, and find it hard to accept the influence of unrelated or random factors. This false logic can lead us to take wrong decisions. Unfortunately, this is the pattern of observations when we consider only our own clinical experience to decide therapy. The fatality of error will be greater the lower our sample is (i.e., clinical experience). Our brain, by several factors, does not have the ability to eliminate the confounding factors associated with a phenomenon. For this reason we appeal to the aid of statistics. But we cannot deceive ourselves, it also does not represent the end of the road and, often reaffirms the thought of Dunkels, in the title.
The hypothesis to be tested should examine, through a well-designed study, the incidence of bone cysts in a group of individuals who received orthodontic treatment, and compare them with a control group without orthodontic intervention. After the data collecting, the results would require a statistical approach to define what is the probability of the observed difference between groups not having occurred by chance ? or, in other words, that the association between the incidence of cysts and orthodontic treatment is actually true. In statistics, the probability of a fortuity (or the difference to be a lie) is measured by the p value, present in almost all scientific studies. Therefore, the smaller the p value is, the smaller the chance of error in stating the association.
Of course, the experience accumulated over the years of clinical activity should not be thrown away. In fact, it is estimated that only 15% of our clinical decisions are supported by scientific evidence.
Therefore, most of the attitudes are taken based on the clinical routine, or what we have been transmitted by our tutors. Science itself, which is settled into solid methods, has been in some battles on the decision about what is more appropriate for a given clinical situation. If we consider solely the opinions held by clinical experience, it increases our probability of error, the same p value. In other words: our truth being, in fact, a lie.
As an orthodontist, with some clinical experience, and a researcher, with some learning in statistics, I believe that the best evidence is not a single study, even a randomized clinical trial, the highest level of evidence from primary studies. Depending on the fact, I consider that, despite its importance, the clinical experience alone is not the best guideline for better treatment in an individual case. Thus, it is not A or B, but the sum A + B. The union of scientific knowledge, derived from the best available evidence ? and therefore, with appropriate statistics ?, and the consolidated clinical experience produces the greatest chances of success when treating a particular patient.
Thus, for younger people, while clinical experience walks slowly, you better hurry up and keep up to date. Enjoy the wealth of scientific research and eminent masters using this modus operandi. For the more experienced clinicians, scientific reading permits a reassessment of its regression or clinical procedures performed on a daily basis, and the identification of the infamous confounders. After all, as the French philosopher Diderot stated: ?He who examined himself is truly advanced in the knowledge of others.? So you have to learn to question your own beliefs. Spend time searching evidences that prove you are wrong, also search for reasons that show how much you?re right. This approach will give you a lower chance of error when treating your next patient. However, consider that this is only the thought of a perpetual learner, who at this time already started doubting his own convictions.
Have a nice reading!
What´s new in Dentistry
The future of dentistry: How will personalized medicine affect orthodontic treatment?
An interview with Hugo De Clerck
- ?Hugo De Clerck is a graduate of the Rijksuniversiteit Gent?s orthodontic program, he received his PhD in 1986 and he maintains a private practice in Brussels. He received the European Research Essay Award in 1988. He has been Professor and Chairperson of the Department of Orthodontics at the Université Catholique de Louvain from 1989 to 2006. Currently he is Adjunct Professor at the University of North Carolina at Chapel Hill. He is the former President of the Belgian Orthodontic Society and Fellow of the Royal College of Surgeons of England. His main research interests are in skeletal anchorage, biomechanics and orthopedics. He lectured extensively on these topics throughout the world.
There are rare moments in which one can be present in a revolution, a paradigm shift or a promising discovery. If we place this fact into our professional universe, chances are even smaller. Faced with a novelty, we may note optimistic reactions by some, and skeptical by others. The optimists are avid to learn and use the novelty, desiring to offer comfort to those they can be of help. On the other hand, the skeptical, suspiciously, prefer that the optimistic try first, make their mistakes first, so that, afterwards it is worthy to leave their comfort zone ? if possible, while the new is not yet old. If you are an optimist or a skeptical, one thing I guarantee: It is impossible to read this interview without becoming a witness of orthodontic history.
Advances in knowledge about induced tooth movement Part 1: The osteocytes
Osteocytes. Mechanotransduction. Tooth movement. Sclerostin. RANKL.
Osteoblasts and clasts were primary targets for the understanding of bone biopathology. In recent years, evidence has shifted attention to the osteocytes. The biology of induced tooth movement and jaw orthopedics should research the role of osteocytes and the specific effects of mediators such as RANKL and sclerostin. The sclerostin represents a regulatory molecule: When more bone is necessary, osteocytes release less sclerostin, when it is necessary to inhibit bone formation, osteocytes release more sclerostin. RANKL is connected to local osteoclastogenesis in order to have more cells capable of reabsorbing the mineralized matrix. New therapeutic ways of controlling the metabolic bone diseases have been targeted at these mediators.
The orthodontist's profile in Minas Gerais
Orthodontics practice. Orthodontics in Minas Gerais state. Orthodontics in Brazil.
Objective: Due of the growing number of orthodontists and courses in Orthodontics, interest has grown in having a profile of these practitioners in Minas Gerais state (Brazil), showing how do they work in order to promote excellence in orthodontics, showing the most used techniques, the changes in the target public, and other views that impact on the future of the specialty and professional groups.
Methods: Questionnaires were sent to all orthodontists registered with the Regional Council of Dentistry of Minas Gerais (Conselho Regional de Odontologia de Minas Gerais, CRO-MG) until March 30, 2005, consisting of 722 professionals. Questionnaires were sent back by 241 (33%) professionals.
Conclusions: This study clarified some relevant aspects about the profile of orthodontists in Minas Gerais regarding their individuality, training and the techniques used. The patient base was composed mainly of teenagers (33.75%) and young adults (27.45%), with referral predominantly by the patients themselves (46.79%). Among the most important facts, we can mention the lack of use of some individual protection equipment, with only 37.76% using all the features of biological safety. Final exams have been requested less frequently than initial records, and findings from the literature review is even more frightening, considering the importance of these records. Looking at the future of the profession, optimistic orthodontists did not exceed half (45%) of participants.
Quantitative assessment of S. mutans and C. albicans in patients with Haas and Hyrax expanders
Orthodontics. Orthodontic appliances. Streptococcus mutans. Candida albicans. Palatal expansion technique.
Objective: To assess and compare the number of Streptococcus mutans and Candida albicans colonies in patients with Haas and Hyrax appliances before and after insertion.
Methods: The sample consisted of 84 patients requiring orthodontic treatment. For all patients a midpalatal suture expansion was indicated. Patients were randomly divided into Group HA, who used the Haas appliance (n = 42) and Group HY, who used the Hyrax appliance (n = 42). Initially and thirty days after appliance insertion all patients were submitted to saliva collections. The saliva was diluted followed by seeding in Mitis Salivarius and CHROMagar media, for growth of S. Mutans and C. Albicans respectively.
Results: Results showed statistically significant difference between groups HA and HY for Streptococcus mutans and Candida albicans (p <0.05). Haas appliance promoted greater S. mutans and C. albicans proliferation when compared to Hyrax appliance.
Conclusion: The Haas appliance favored greater proliferation of S. mutans and C. albicans when compared with the Hyrax appliance. Insertion of the appliances resulted in greater buildup of microorganisms.
Comparative analysis of load/deflection ratios of conventional and heat-activated rectangular NiTi wires
Orthodontics. Orthodontic wires. Qualitative analysis.
Objective: This study compared the load-deflection ratios between 0.019 x 0.025-in rectangular orthodontic wires using 5 conventional preformed nickel-titanium (NiTi) and 5 heat-activated NiTi archwires from four different manufacturers (Abzil, Morelli, 3M Unitek and Ormco), totaling 40 archwires. The archwires were placed in typodonts without tooth # 11 and tested using a universal testing machine connected to a computer.
Results: The comparisons of mean load-deflection values of conventional NiTi wires revealed that the lowest mean-deflection ratio was found for 3M Unitek, followed by Ormco, Morelli and Abzil. Regarding the heat-activated wires, the lowest load-deflection ratio was found for Ormco, followed by 3M Unitek, Abzil, and Morelli.
Conclusion: The comparison of mean load-deflection ratios revealed that the heat-activated wires had lowest mean load-deflection ratios, and this trend was seen during all the study. However, at 2-mm deflection, mean load-deflection ratios for heat-activated Morelli and conventional 3M Unitek wires were very similar, and this difference was not statistically significant.
Influence of certain tooth characteristics on the esthetic evaluation of a smile
Smile. Dental esthetics. Perception.
Objective: To assess the influence of certain dental characteristics on the perception of smile esthetics by undergraduate dentistry students.
Methods: Ten digital photographs of a woman?s smile were modified using Adobe Photoshop software. The following changes were performed: stain removal; incisal edge straightening; gingival leveling; closure of black triangles. A group of 60 undergraduate dental students evaluated the original photograph and the altered images using a visual analog scale to evaluate smile esthetics. Intraexaminer agreement was checked for 30 examiners using the Student t test; for casual error, the Dahlberg formula was used. Data were described as means and standard deviations, and reported in tables.
Results: There were no statistically significant differences between the first and second scores assigned by examiners (p>0.05) in any of the comparisons made. The results of systematic error for the method indicated that the measures obtained were reliable. ANOVA was used to test equality of means, and the level of significance was set at 5%. Equality of variances was evaluated using Levene?s test, and results revealed that variances were equal. Multiple comparisons using the Tukey?s test revealed statistical significance at a 5%level for the presence of black triangular space. No significant values were found for other comparisons.
Conclusions: Some dental characteristics were perceived by undergraduate students, and the black triangular space was classified as the most unfavorable characteristic.
Pigment effect on the long term elasticity of elastomeric ligatures
Ligatures. Elastomers. Color. Elasticity
Objective: To evaluate the response of elastomeric ligatures in several colors for a 4 mm traction over time.
Methods: Morelli® elastomeric ligatures, were submitted to traction forces using two rods of circular cross section, until a 4 mm distance was reached, matching the approximate diameter of an upper central incisor bracket of the same manufacturer. The ligatures were kept in artificial saliva immersion at 37 °C. Forces levels were measured immediately (0 h), 2, 4, 6, 8, 10, 12, 24, 48, 72, 96 hours, 1, 2, 3, 4 weeks and results were submitted to two-way repeated-measures ANOVA statistical analysis.
Results: The gray samples showed the higher initial values of tensile strength. The lowest values were presented by purple, light pink, green, black and red groups. The greater tensile strength instability was presented by red, black, silver, green and gray groups. The greater tensile strength stability was presented by deep pink, dark blue, blue, purple and light pink groups.
Conclusion: Elastomeric ligatures do not present stable behavior when suffering traction forces over time and different colors display different behaviors. Deep pink, dark blue, blue, purple and light pink groups, displayed the most stable forces, suggesting that they should be used during the treatment to obtain constant forces.
Interrelation between orthodontics and phonoaudiology in the clinical decision-making of individuals with mouth breathing
Mouth breathing. Orthodontics. Speech therapy.
Objective: The purpose of this study was to investigate the decision making of orthodontists of Passo Fundo district - Rio Grande do Sul (RS)/Brazil, in the Orthodontics/Speech Therapy interdisciplinary treatment of mouth breathing individuals.
Methods: The present study is a quantitative approach and the design is descriptive, using as instrument data collection of a questionnaire sent to 22 orthodontists practicing in the above-mentioned district. The project was approved the the Ethics in Research Committee and all individuals signed a free informed consent.
Results: All professionals considered the inter-relation between Orthodontics and Speech Therapy necessary, but divergences were found in situations where a associated therapy may exist, considering that 54.5% trust the inter-relation to develop aspects associated to language, oral facial motricity and habits. In cases of associated treatment, the results obtained were considered satisfactory by 73.7% of professionals, even though they consider that only 6 to 20% of their patients collaborate with treatment.
Conclusion: In relation to decision-making in treatment of mouth breathing individuals, the orthodontists in Passo Fundo/RS agree that there is need for speech therapy. The full vision of the individual in a multidisciplinary team is of fundamental importance in the treatment of patients with mouth breathing syndrome.
Influence of Ortho Primer Morelli adhesion booster on orthodontic brackets shear bond strength
Primer. Adhesion. Shear adhesive strength.
Objective: This work aimed at assessing the bond strength (AS), the site of the flaw and the relation between them and Ortho Primer Morelli® (OPM) adhesion optimizer.
Methods: Sixty test specimens, made out of bovine permanent lower incisors, were divided into three groups: TXT Primer (control), in which a conventional adhesive system was applied (primer and paste); OPM, in which TXT primer was replaced by OPM; and TXT without Primer, in which only TXT paste was used. A shear force was applied at a speed of 0,5 mm/min. Failure site was assessed by the Remaining Adhesion Index (RAI).
Results: Kruskal-Wallis demonstrated that OPM (8.54 ± 1.86 MPa) presented a statistically higher AS (p < 0.05) IF compared to TXT Primer (6.83 ± 2.05 MPa). There was no statistically significant difference (p > 0.05) between TXT with or without Primer (6.42 ± 2.12 MPa). Regarding the RAI, the K test demonstrated that TXT Primer and OPM (prevailing scores 2 and 3) showed higher values (p < 0.05) IF compared to TXT without Primer (prevailing scores 0 and 1). Spearman demonstrated that there was no correlation between AS and RAI (p > 0.05).
Conclusion: OPM increases AS and presents the same bond failure location if compared to a conventional adhesive system; the use of the TXT adhesive system paste only was shown to have the same AS if compared to conventional systems, except it does not allow to predict the adhesive failure site; there is no correlation between AS and bond failure location, regardless of the use of any adhesion optimizer.
Assessment of the mandibular symphysis of Caucasian Brazilian adults with well-balanced faces and normal occlusion: The influence of gender and facial type
Mandibular symphysis. Gender. Facial type. Facial balance.
Objective: This study aimed to establish cephalometric reference values for mandibular symphysis in adults. Dentoalveolar, skeletal and soft tissue variables were measured considering the influence of gender and facial type.
Methods: The sample consisted of sixty cephalometric radiographs of white Brazilian adult patients, with a mean age of 27 years and 6 months, who had not undergone orthodontic treatment and who presented well-balanced faces and normal occlusion. The sample was standardized according to gender (30 males and 30 females) and facial type (20 were dolichofacial, 20 mesofacial and 20 brachyfacial).
Results: The results showed that male and female symphyses are similar, except for symphyseal height, which was greater in males. In terms of facial type, the dolichofacial group presented narrower symphysis in dentoalveolar and basal areas, with a more accentuated lingual dentoalveolar inclination.
Conclusion: The brachyfacial group showed broader symphysis in the dentoalveolar and basal areas and a greater buccal dentoalveolar inclination. The projection of the chin was 6.67 mm below the subnasal vertical line and there was no significant difference between the genders or facial types.
Evaluation of the lower incisor inclination during alignment and leveling using superelastic NiTi archwires: A laboratory study
Arch shape. Superelastic NiTi archwire. Arch length. Incisor tipping.
Objective: The aim of this laboratory study is to evaluate the influence of the shape and the length limitation of superelastic nickel-titanium (NiTi) archwires on lower incisors inclination during alignment and leveling.
Methods: Metal teeth mounted on a typodont articulator device were used to simulate a malocclusion of the mandibular arch (-3.5 mm model discrepancy). Three different shapes (Standard, Accuform and Ideal) of superelastic NiTi archwires (Sentalloy, GAC, USA) were tested. Specimens were divided in two groups: Group I, with no limitation of the archwire length; and Group II, with distal limitation. Each group had thirty specimens divided into three subgroups differentiated by the archwire shape. All groups used round wires with diameters of 0.014-in, 0.016-in, 0.018-in and 0.020-in. The recording of all intervals was accomplished using standardized digital photographs with orthogonal norm in relation to median sagittal plane. The buccolingual inclination of the incisor was registered using photographs and software CorelDraw.
Results: The results were obtained using ANOVA and Tukey?s test at a significant level of 5%. The inclination of the lower incisor increased in both groups and subgroups. The shape of the archwire had statistically significant influence only in Group I ? Standard (11.76°), Ideal (5.88°) and Accuform (1.93°). Analyzing the influence of the length limitation, despite the mean incisor tipping in Group II (3.91°) had been smaller than Group I (6.52°), no statistically significant difference was found, except for Standard, 3.89° with limitation and 11.76° without limitation. The greatest incisor tipping occurred with the 0.014-in archwires.
Snoring and Obstructive Sleep Apnea Syndrome: A reflection on the role of Dentistry in the current scientific scenario
Snoring. Obstructive sleep apnea and hypopnea. Occlusal plates.
Introduction: Finally the dentist has awaken to the fact that by being a health professional, he has as primary function to take good care of the welfare of patients. In face of this challenge, the dentist starts to understand his role in the treatment of snoring and of obstructive sleep apnea and hypopnea.
Objective: The current paper has the purpose of discussing the role of this professional in the diagnosis and treatment of these diseases, most specifically of the therapy involving inter-occlusal devices, emphasizing the importance of multidisciplinarity in the reestablishment of the quality of life of the patient.
Comparative study of classic friction among different archwire ligation systems
Corrective Orthodontics. Orthodontic brackets. Friction.
Objective: To describe and compare three alternative methods for controlling classical friction: Self-ligating brackets (SLB), special brackets (SB) and special elastomeric ligatures (SEB).
Methods: The study compared Damon MX, Smart Clip, In-Ovation and Easy Clip self-ligating bracket systems, the special Synergy brackets and Morelli?s twin bracket with special 8-shaped elastomeric ligatures. New and used Morelli brackets with new and used elastomeric ligatures were used as control. All brackets had 0.022 x 0.028-in slots. 0.014-in nickel-titanium and stainless steel 0.019 x 0.025-in wires were tied to first premolar steel brackets using each archwire ligation method and pulled by an Instron machine at a speed of 0.5 mm/minute. Prior to the mechanical tests the absence of binding in the device was ruled out. Statistical analysis consisted of the Kruskal-Wallis test and multiple non-parametric analyses at a 1% significance level.
Results: When a 0.014-in archwire was employed, all ligation methods exhibited classical friction forces close to zero, except Morelli brackets with new and old elastomeric ligatures, which displayed 64 and 44 centiNewtons, respectively. When a 0.019 x 0.025-in archwire was employed, all ligation methods exhibited values close to zero, except the In-Ovation brackets, which yielded 45 cN, and the Morelli brackets with new and old elastomeric ligatures, which displayed 82 and 49 centiNewtons, respectively.
Conclusions: Damon MX, Easy Clip, Smart Clip, Synergy bracket systems and 8-shaped ligatures proved to be equally effective alternatives for controlling classical friction using 0.014-in nickel-titanium archwires and 0.019 x 0.025-in steel archwires, while the In-Ovation was efficient with 0.014-in archwires but with 0.019 x 0.025-in archwires it exhibited friction that was similar to conventional brackets with used elastomeric ligatures.
Nickel-titanium alloys: A systematic review
Nickel-titanium wires. Thermoelasticity. Shape memory alloys. Superelasticity.
Objective: A systematic review on nickel-titanium wires was performed. The strategy was focused on Entrez-PubMed-OLDMEDLINE, Scopus and BioMed Central from 1963 to 2008.
Methods: Papers in English and French describing the behavior of these wires and laboratorial methods to identify crystalline transformation were considered. A total of 29 papers were selected.
Results: Nickel-titanium wires show exceptional features in terms of elasticity and shape memory effects. However, clinical applications request a deeper knowledge of these properties in order to allow the professional to use them in a rational manner. In addition, the necessary information regarding each alloy often does not correspond to the information given by the manufacturer. Many alloys called ?superelastic? do not present this effect; they just behave as less stiff alloys, with a larger springback if compared to the stainless steel wires.
Conclusions: Laboratory tests are the only means to observe the real behavior of these materials, including temperature transition range (TTR) and applied tensions. However, it is also possible to determine in which TTR these alloys change the crystalline structure.
Evaluation of the mechanical behaviour of different devices for canine retraction
Corrective Orthodontics. Canine tooth. Malocclusion.
Objective: To mechanically evaluate different systems used for canine retraction.
Methods: Three different methods for partial canine retraction were evaluated: retraction with elastic chain directly attached to bracket; elastic chain connected to bracket hook and with sliding jig activated with the aid of an elastic chain attached to a mini-implant. For this evaluation, a Typodont was adapted to simulate the desired movements when exposed to a heat source. After obtaining the measurements of the movements, statistical analysis was performed.
Results: The mini-implant/sliding jig system (Groups M 0.018-in and M 0.019 x 0.026-in) favored less extrusion and distal inclination of the canines in the retraction stage (p < 0.005). Meanwhile, the retraction system with elastic chain directly attached to the orthodontic brackets (Groups C 0.018-in and 0.019 x 0.026-in) favored greater inclination and extrusion than the others, followed by the system of elastic chain attached to the hook (Groups G 0.018-in and 0.019 x 0.026-in).
Conclusions: Canine retraction with the mini-implant/sliding jig system showed the best mechanical control. The worst results were observed with a 0.018 archwire when the elastic chain was attached to the bracket.
Assessment of divine proportion in the cranial structure of individuals with Angle Class II malocclusion on lateral cephalograms
Divine Proportion. Class II malocclusion. Cephalometry.
Introduction: The study of the Divine Proportion (? = 1.618) began with the Greeks, having as main researchers the mathematician Pythagoras and the sculptor Phidias. In Dentistry, Ricketts (1981-82) was an early to study this issue.
Objective: This study proposed to evaluate how some cephalometric measures are presented in relation to the Divine Proportion, with the total of 52 proportions, formed by 28 cephalometric landmarks.
Methods: Lateral cephalograms of 40 Class II adults patients aging from 17 to 45 years (13 male and 27 female) were evaluated. The linear distances between the landmarks were measured using Radiocef Studio software.
Results: After statistical analysis, the data shown an average of 65,48% in the Divine Proportion, 17,5% in the relation Ans-Op/V1S-DM16 and 97,5% in the relations Na-Me/Na-PoNa e Na-PoNa/Na-Gn.
Conclusion: Among all cephalometric measurements investigated, the lower facial third and the dental arches showed the smallest percentages of Divine Proportion.
Orthodontics as a therapeutic option for temporomandibular disorders: A systematic review
Temporomandibular joint dysfunction syndrome. Temporomandibular joint disorders. Craniomandibular disorders. Temporomandibular joint. Orthodontics. Dental occlusion.
Objective: Orthodontics as an option for treatment and prevention of Temporomandibular Disorders (TMD) is a topic that has generated discussion over time. While an occlusion current defends Orthodontics as an alternative to treatment, another current defends more conservative and reversible treatments. The objective of this study, through a systematic literature review, was to analyze the relationship between Orthodontics and TMD, checking the effects of orthodontic therapy in treatment and prevention of TMD.
Methods: Survey in research bases: MEDLINE, Cochrane, EMBASE, Pubmed, Lilacs and BBO, between the years of 1966 and May 2009, with focus in randomized clinical trials, non-randomized prospective longitudinal studies, systematic reviews and meta-analysis was performed.
Results: After application of the inclusion criteria 11 articles were selected, 9 which were non-randomized prospective longitudinal studies, 1 randomized clinical trial and 1 systematic review.
Conclusions: According to the literature, there is a lack of specific studies that evaluated Orthodontics as an option for treatment and prevention of TMD. Thus the data conclude that there is no significant scientific evidences that orthodontic treatment treats or prevents TMD.
In vitro evaluation of flexural strength of different brands of expansion screws
Palatal expansion technique. Corrective orthodontics. Malocclusion.
Objective: The objective of this study was to compare the flexural strength of the stems of three maxillary expanders screws of Morelli, Forestadent and Dentaurum brands.
Methods: The sample consisted of nine expander screws (totalizing of 36 stems), three from each brand, all stainless steel and 12 mm of expansion capacity. The stems of the expander screws were cut with cutting pliers close to the weld region with screw body, then fixed in a universal testing machine Instron 4411 for tests of bending resistance of three points. The ultimate strength in kgF exerted by the machine to bend the stem of the 5 mm screw was recorded and the flexural strength was calculated using a mathematical formula. During the flexural strength test it was verified the modulus of elasticity of the stems by means of Bluehill 2 software. The flexural strength data were subjected to ANOVA with one criterion and Tukey?s test, with significance level of 5%.
Results: Forestadent screw brand showed the greatest bending strength, significantly higher than Dentaurum. Morelli showed the lowest resistance.
Conclusion: The flexural strength of the screws varied according to the brand. Forestadent screw showed the greatest resistance and Morelli the lowest. All the three screws were found adequate for use in procedures for rapid maxillary expansion.
Histomorphometric evaluation of periodontal compression and tension sides during orthodontic tooth movement in rats
Tooth movement. Periodontal ligament. Periodontium.
Objective: The purpose of this study was to evaluate the thickness of the periodontal ligament of rat molars during orthodontic tooth movement (OTM).
Methods: Thirty Wistar rats were divided into three groups of 10 animals each: GI, GII and GIII and the mice were euthanized at 7, 14 and 21 days, respectively. Experimental subjects were compared to their respective controls by the Mann-Whitney test. Comparison of values between compression and tension sides were performed during the same and different time periods through Analysis of Variance (ANOVA), Kruskal-Wallis test and, subsequently, Tukey?s test.
Results: Groups GI and GII showed decreased PDL size in the apical regions of the mesiobuccal root and in the cervical region of the distobuccal root. There was also an increased PDL in the cervical regions of the mesiobuccal root, apical region of the distobuccal root and middle region of both roots.
Conclusion: The reduction and increase in PDL size were seen in the same root, which characterizes tooth inclination. The apical, middle and cervical regions were compared with one another in each time period and at three times: 7, 14 and 21 days. They were also compared in each region, confirming a tipping movement in GI and GII and a gradual decreased intensity between GI to GII, reaching normal dimension in GIII.
Orthopedic treatment of Class III malocclusion with rapid maxillary expansion combined with a face mask: A cephalometric assessment of craniofacial growth patterns
Angle Class III malocclusion. Cephalometrics. Headgear appliances. Maxillary expansion.
Methods: Lateral cephalometric radiographs were taken at beginning (T1) and immediately after removal of the appliances (T2), average of 11 months of treatment. Linear and angular measurements were used to evaluate the cranial base, dentoskeletal changes and facial growth pattern.
Results: The length of the anterior cranial base experienced a reduction while the posterior cranial base assumed a more vertical position at T1. Some maxillary movement occurred, there was no rotation of the palatal plane, there was a slight clockwise rotation of the mandible, although not significant. The ANB angle increased, thereby improving the relationship between the jaws; dentoalveolar compensation was more evident in the lower incisors. Five out of 12 cases (29.41%) showed the following changes: In one case the pattern became more horizontal and in four cases more vertical.
Conclusions: It was concluded after a short-term assessment that treatment with rapid maxillary expansion (RME) associated with a face mask was effective in the correction of Class III malocclusion despite the changes in facial growth pattern observed in a few cases.
Evaluation of the position of lower incisors in the mandibular symphysis of individuals with Class II malocclusion and Pattern II profiles
Diagnosis. Angle Class II malocclusion. Cranial circumference.
Objectives: This study evaluated the position of mandibular incisors in the mandibular symphysis of individuals with Class II malocclusion and Pattern II profiles.
Methods: The sample consisted of 40 Caucasian patients (20 male and 20 female) with Class II malocclusion and Pattern II profile from 10 to 18 years of age (mean age of 12.84 years) who were selected from the records of the School of Dentistry of Universidade de Passo Fundo, Brazil. The linear cephalometric measurements used in this study were Ricketts? 1- AP, Interlandi?s line I and Vigorito?s 1-VT; and the angular measurement studied was the mandibular plane angle (IMPA).
Results: Mandibular incisors of individuals with Class II malocclusion and Pattern II profile tended to be buccally inclined and protruded.
Assessment of facial profile changes in Class I biprotrusion adolescent subjects submitted to orthodontic treatment with extractions of four premolars
Class I Angle malocclusion. Dental extraction. Dental esthetics. Facial profile.
Objective: To evaluate cephalometric changes in tooth and profile position in young adolescent individuals with Class I biprotrusion submitted to orthodontic treatment with extractions of four first premolars.
Methods: Pre and post-treatment lateral cephalometric radiographs from 20 patients with Class I biprotrusion malocclusion were used to evaluate the following measurements: nasolabial angle, distance from lips to E line, distance from lips, incisors, tip of the nose and soft tissue pogonion to Sy line.
Results: All measurements showed significant changes after treatment (p<0.05), except the distance from lips and soft tissue pogonion to Sy line. There was a positive correlation between the retraction of incisors and the change of upper and lower lips (0.803/0.925; p<0.001).
Conclusion: The profile retrusion observed occurred more due to nose growth than to lips retraction. The response from soft tissues to incisors retraction showed a great variability.
BBO Case Report
Compensatory treatment of Angle Class III malocclusion with anterior open bite and mandibular asymmetry
Facial asymmetry. Orthodontics. Angle Class III malocclusion.
Class III malocclusion is characterized by anterior posterior dental disharmony, either with or without skeletal discrepancies. Facial esthetics may be compromised to a greater or lesser degree, depending on the magnitude of the discrepancy, and is one of the main factors motivating individuals to seek orthodontic treatment. In adult patients, therapy may be performed by means of dental compensation, in simpler cases, or in more severe situations, by means of association between Orthodontics and Orthognathic Surgery. The present article is a clinical case report of a patient with a vertical facial pattern, Angle Class III malocclusion, with open bite and important facial asymmetry. The patient was treated in a compensatory manner with extractions, using extra-oral appliances on the mandibular arch with high pull, applying the principles of the Tweed-Merrifield technique. This case was presented to the Brazilian Board of Orthodontics and Facial Orthopedics (BBO) as part of the requisites for becoming a BBO Diplomate.
Preparation and evaluation of orthodontic setup
Orthodontics. Diagnosis and planning. Dental casts
Introduction: An orthodontic or diagnostic setup consists in cutting and realigning the teeth in plaster models, making it an important resource in orthodontic treatment planning.
Objective: The aim of this article is to provide a detailed description of a technique to build an orthodontic setup model and a method to evaluate it.
Conclusions: Although laborious, orthodontic setup procedure and analysis can provide important information such as the need for dental extractions, interproximal stripping, anchorage system, among others.