v. 19, no. 1
Dental Press Journal of Orthodontics – ISSN 2176-9451
Dental Press J. Orthod.
v. 19, no. 1
January / February
Writing a scientific paper: Where to start from?
“Our end was just the beginning.” (Yuri Popoff, bassist and composer from Minas Gerais)
It is not our aim, in the next few lines, to make our reader become a contumacious scientific writer. Scientific writing requires practice and there are only a few courses that can guide us to a shortcut. However, there are some useful pieces of advice that I pass on based on the experience I have had as a reviewer, editor and, especially, as an author.
Good scientific research begins with an original idea that is put into practice by means of a robust methodology. If there is a good question, the answer will come in a more interesting way. Once you reliably find the answer, you will only need a low dose of efficient communication. I have come across excellent papers that get lost due to poor writing. However, the opposite is more common. The board of editors will be more interested in correcting minor writing mistakes.
Where to start from? How about the end? Exactly. Start with the conclusion. To my view, one of the most common mistakes is to start writing by the introduction. How can we present something if we do not know what it is? This ordinary path, in my opinion, results from the attempt to make the best of the project that originated the study we write about. As a consequence, we end up with a long introduction that is far from conveying the main message of the research: the conclusion. Thus, starting with the conclusion infuses our mind with the draft of the path that we would like to reveal to our readers.
Afterwards, it is important to keep the conclusion in mind to write the paper in a brief and linear manner. Another common mistake in scientific writing is to be prolix, write more than necessary, especially in the introduction. The researcher intensely lives what he does, sleeping and dreaming about the object of his experiment or observation. And through inebriant osmosis, he starts to believe that everything he writes is utterly important. However, it is worth that the author put himself in the reader’s shoes. In this case, less is more. We live in the age of — fast — communication. Short texts and the right words are more appropriate. For this reason, simply read and reread what you have written, and, without fear or guilt, cut everything you think will hinder the comprehension of the text. Many scientific journals of great impact, such as Nature and Science, require that the authors submit much shorter texts than we are used to in Dentistry field. There is a good reason for that.
Draft. That’s it. Draw up a strategic draft, a sketch of all the information you would like to present and define where every item will be within the structure of the text. Remember to keep the conclusion in mind. As you find new interesting information, first ask yourself whether this knowledge is really important for the comprehension of the text. Only after you find an affirmative convincing answer, point out where this questioning will be in the structure of the text.
Within the IMRaD structure (Introduction, Methodology, Results and Discussion), after the conclusion, I usually move forward to the results, followed by the discussion and the material and methods. The introduction is the last part. In all of these parts, do not hesitate to cut the excesses. Researchers usually find it difficult to discard data that did not produce any useful information in their experiment. Similarly, they find it difficult to understand the reason why we have to take a step back in order to search for new information that may be key to the success of the study. Eliminating excessive data greatly facilitates the process of writing a manuscript.
Leave the title to the end. You may even write a temporary title, however, when the text is ready, analyze if the title is suitable to communicate its content, especially what is in the conclusion. We have to understand that the title is the abstract of the abstract, and that is the reason why it should not be too long. Long titles, as well as long texts, instigate readers’ disinterest. The title does not have to necessarily communicate everything.
Reread the title of this editorial. All right, this is not a research. An editorial is freer to flow. But analyze it. The text does not reflect on how to start writing a manuscript, only. There are other pieces of information. Should I have mentioned all pieces of information in the title, our beginning would have reached its end right there.
Force distribution is more important than its intensity!
Orthodontic forces. Induced tooth movement. Root resorption.
A common question about root resorption is raised in orthodontic practice: What is more important, the intensity of force or its distribution along the root, periodontal and alveolar structures? Diffuse distribution of forces applied to periodontal tissues during tooth movement tends not to promote neither extensive areas of cell matrix hyalinization nor significant death of cementoblasts that lead to root resorption. However, focal distribution or concentration of forces within a restricted area — as it occurs in tipping movements, even with forces of lower intensity — tend to induce extensive areas of hyalinization and focal death of cementoblasts, which is commonly associated with root resorption. In tipping movements, the apical regions tend to concentrate more forces in addition to wounding the cementoblasts due to the smaller dimension of their root structure as well as their cone shape. For this reason, there is an increase in root resorption. In the cervical region, on the other hand, the large area resulting from a large diameter and bone crown deflection tends to reduce the effects of forces, even when they are more concentrated, thus rarely inducing death of cementoblasts and root resorption.
What is the meaning of this lowercase “p”?
Most health professionals are resistant to statistics. There is nothing inconsistent about it: if they liked Mathematics as a profession, they would have chosen a career in the exact sciences.
Clinical dentists are not different: most of them prefer to avoid greater proximity to, and as a consequence, understanding of statistics. Undoubtedly, many statistical procedures involve complex and difficult-to-understand calculation for those who do not have expertise in this area.
An interview with Kazuo Tanne
Professor Kazuo Tanne has a degree in Dentistry by the University of Osaka where he also received the title of PhD in Orthodontics. From the 1st of July, 1993 to the 31st of March, 2013 he was the head of the Department of Orthodontics and Craniofacial Development Biology at the University of Hiroshima, in Japan. Professor Tanne has been the head of the Japanese Association of Cleft Lip/Palate, and nowadays is the head of the Asian Orthodontic Society which comprises 18 orthodontic societies in the Asia/Pacific area. He has published more than 700 articles and more than 60 books and/or chapters about many different topics. Professor Tanne has conducted interesting researches that focus on temporomandibular disorders, tooth cryopreservation, cleft lip/palate, molecular/cell biology and genetic engineering for bone repair. I am honored to say that I was advised by Professor Tanne during my Doctorate in Orthodontics between 2006 and 2010. During that period, I had the opportunity to fulfill my expectations towards the excellence of education provided by the University of Hiroshima as well as by Professor Tanne who also proved to be a great human being with a noble heart. We have become great friends and fortunately I had the chance to learn much more than Orthodontics. Tanne Sensei, as he is known in Japan, has a deep admiration for Brazil and the Brazilian culture. He has been in Brazil in three occasions, when he made friends in many different locations.
Emanuel Braga Rêgo
Dental and skeletal components of Class II open bite treatment with a modified Thurow appliance
Angle Class II malocclusion. Open bite. Orthopedics.
Introduction: Due to the lack of studies that distinguish between dentoalveolar and basal changes caused by the Thurow appliance, this clinical study, carried out by the School of Dentistry — State University of São Paulo/Araraquara, aimed at assessing the dental and skeletal changes induced by modified Thurow appliance.
Methods: The sample included an experimental group comprising 13 subjects aged between 7 and 10 years old, with Class II malocclusion and anterior open bite, and a control group comprising 22 subjects similar in age, sex and mandibular plane angle. Maxillary/mandibular, horizontal/vertical, dental/skeletal movements (ANS, PNS, U1, U6, Co, Go, Pog, L1, L6) were assessed, based on 14 landmarks, 8 angles (S-N-ANS, SNA, PPA, S-N-Pog, SNB, MPA, PP/MPA, ANB) and 3 linear measures (N-Me, ANS-Me, S-Go).
Results: Treatment caused significantly greater angle decrease between the palatal and the mandibular plane of the experimental group, primarily due to an increase in the palatal plane angle. ANB, SNA and S-N-ANS angles significantly decreased more in patients from the experimental group. PNS was superiorly remodeled. Lower face height (ANS-Me) decreased in the experimental group and increased in the control group.
Conclusions: The modified Thurow appliance controlled vertical and horizontal displacements of the maxilla, rotated the maxilla and improved open bite malocclusion, decreasing lower facial height.
An assessment of the maxilla after rapid maxillary expansion using cone beam computed tomography in growing children
Palatal expansion technique. Orthodontics. Cone beam computed tomography. Cranial sutures.
Introduction: With the advent of cone beam computed tomography (CBCT), it is now possible to quantitatively evaluate the effects of rapid maxillary expansion (RME) on the entire maxillary complex in growing patients.
Objective: The purpose of this study is to use three-dimensional images to evaluate the displacement that occurs at the circummaxillary sutures (frontonasal, zygomaticomaxillary, intermaxillary, midpalatal, and transpalatal sutures) following rapid maxillary expansion in growing children.
Methods: The CBCT scans of 25 consecutively treated RME patients (10 male, 15 female) with mean age of 12.3 ± 2.6 years, were examined before expansion and immediately following the last activation of the expansion appliance.
Results: Statistically significant (P < 0.05) amounts of separation were found for the displacement of the bones of the frontonasal suture, the intermaxillary suture, the zygomaticomaxillary sutures, and the midpalatal suture. The change in angulation of the maxillary first molars due to RME was also statistically significant. There was no statistically significant displacement of the transpalatal suture.
Conclusions: Rapid maxillary expansion results in significant displacement of the bones of circummaxillary sutures in growing children.
Dentoskeletal effects of Class II malocclusion treatment with the Twin Block appliance in a Brazilian sample: A prospective study
Angle Class II malocclusion. Skull circumference. Functional orthodontic appliances. Prospective studies. Treatment outcome.
Objective: The aim of this study was to assess the dentoskeletal effects of Class II malocclusion treatment performed with the Twin Block appliance.
Methods: The experimental group comprised 20 individuals with initial mean age of 11.76 years and was treated for a period of 1.13 years. The control group comprised 25 individuals with initial mean age of 11.39 years and a follow-up period of 1.07 years. Lateral cephalograms were taken at treatment onset and completion to assess treatment outcomes. Intergroup comparison was performed by means of the chi-square and independent t tests.
Results: The Twin Block appliance did not show significant effects on the maxillary component. The mandibular component showed a statistically significant increase in the effective mandibular length (Co-Gn) and significant improvement in the maxillomandibular relationship. The maxillary and mandibular dentoalveolar components presented a significant inclination of anterior teeth in both arches. The maxillary incisors were lingually tipped and retruded, while the mandibular incisors were labially tipped and protruded.
Conclusions: The Twin Block appliance has great effectiveness for correction of skeletal Class II malocclusion in individuals with growth potential. Most changes are of dentoalveolar nature with a large component of tooth inclination associated with a significant skeletal effect on the mandible.
Dental and skeletal changes in patients with mandibular retrognathism following treatment with Herbst and pre-adjusted fixed appliance
Angle Class II malocclusion. Orthopedics. Orthodontics.
Methods: Lateral cephalograms of 17 adolescents were taken in phase I onset (T1) and completion (T2); in the first thirteen months of phase II (T3) and in phase II completion (T4). Differences among the cephalometric variables were statistically analyzed (Bonferroni variance and multiple comparisons).
Results: From T1 to T4, 42% of overall maxillary growth was observed between T1 and T2 (P < 0.01), 40.3% between T2 and T3 (P < 0.05) and 17.7% between T3 and T4 (n.s.). As for overall mandibular movement, 48.2% was observed between T1 and T2 (P < 0.001) and 51.8% between T2 and T4 (P < 0.01) of which 15.1% was observed between T2 and T3 (n.s.) and 36.7% between T3 and T4 (P < 0.01). Class II molar relationship and overjet were properly corrected. The occlusal plane which rotated clockwise between T1 and T2, returned to its initial position between T2 and T3 remaining stable until T4. The mandibular plane inclination did not change at any time during treatment.
Conclusion: Mandibular growth was significantly greater in comparison to maxillary, allowing sagittal maxillomandibular adjustment. The dentoalveolar changes (upper molar) that overcorrected the malocclusion in phase I, partially recurred in phase II, but did not hinder correction of the malocclusion. Facial type was preserved.
Prevalence of dental anomalies of number in different subphenotypes of isolated cleft palate
Cleft palate. Tooth abnormalities. Panoramic radiograph.
Objective: This study aimed at carrying out a radiographic analysis on the prevalence of dental anomalies of number (agenesis and supernumerary teeth) in permanent dentition, in different subphenotypes of isolated cleft palate pre-adolescent patients.
Methods: Panoramic radiographs of 300 patients aged between 9 and 12 years, with cleft palate and enrolled in a single treatment center, were retrospectively analyzed. The sample was divided into two groups according to the extension/severity of the cleft palate: complete and incomplete . The chi-square test was used for intergroup comparison regarding the prevalence of the investigated dental anomalies (P < 0.05).
Results: Agenesis was found in 34.14% of patients with complete cleft palate and in 30.27% of patients with incomplete cleft palate. Supernumerary teeth were found in 2.43% of patients with complete cleft palate and in 0.91% of patients with incomplete cleft palate. No statistically significant difference was found between groups with regard to the prevalence of agenesis and supernumerary teeth. There was no difference in cleft prevalence between genders within each study group.
Conclusion: The prevalence of dental anomalies of number in pre-adolescents with cleft palate was higher than that reported for the general population. The severity of cleft palate did not seem to be associated with the prevalence of dental anomalies of number.
Are self-ligating brackets related to less formation of Streptococcus mutans colonies? A systematic review
Biofilms. Orthodontic brackets. Streptococcus mutans. Review.
Objective: To verify, by means of a systematic review, whether the design of brackets (conventional or self-ligating) influences adhesion and formation of Streptococcus mutans colonies.
Methods: Search strategy: four databases (Cochrane Central Register of Controlled Trials, Ovid ALL EMB Reviews, PubMed and BIREME) were selected to search relevant articles covering the period from January 1965 to December 2012. Selection Criteria: in first consensus by reading the title and abstract. The full text was obtained from publications that met the inclusion criteria. Data collection and analysis: Two reviewers independently extracted data using the keywords: conventional, self-ligating, biofilm, Streptococcus mutans, and systematic review; and independently evaluated the quality of the studies. In case of divergence, the technique of consensus was adopted.
Results: The search strategy resulted in 1,401 articles. The classification of scientific relevance revealed the high quality of the 6 eligible articles of which outcomes were not unanimous in reporting not only the influence of the design of the brackets (conventional or self-ligating) over adhesion and formation of colonies of Streptococcus mutans, but also that other factors such as the quality of the bracket type, the level of individual oral hygiene, bonding and age may have greater influence. Statistical analysis was not feasible because of the heterogeneous methodological design.
Conclusions: Within the limitations of this study, it was concluded that there is no evidence for a possible influence of the design of the brackets (conventional or self-ligating) over colony formation and adhesion of Streptococcus mutans.
Mechanical properties of NiTi and CuNiTi wires used in orthodontic treatment. Part 2: Microscopic surface appraisal and metallurgical characteristics
Physical properties. Orthodontic wires. Scanning electron microscopy. Nickel. Titanium. Copper.
Objective: This research aimed at comparing the qualitative chemical compositions and the surface morphology of fracture regions of eight types of Nickel (Ni) Titanium (Ti) conventional wires, superelastic and heat-activated (GAC, TP, Ormco, Masel, Morelli and Unitek), to the wires with addition of copper (CuNiTi 27oC and 35oC, Ormco) after traction test.
Methods: The analyses were performed in a scanning electronic microscope (JEOL, model JSM-5800 LV) with EDS system of microanalysis (energy dispersive spectroscopy).
Results: The results showed that NiTi wires presented Ni and Ti as the main elements of the alloy with minimum differences in their composition. The CuNiTi wires, however, presented Ni and Ti with a significant percentage of copper (Cu). As for surface morphology, the wires that presented the lowest wire-surface roughness were the superelastic ones by Masel and Morelli, while those that presented the greatest wire-surface roughness were the CuNiTi 27oC and 35oC ones by Ormco, due to presence of microcavity formed as a result of pulling out some particles, possibly of NiTi4. The fracture surfaces presented characteristics of ductile fracture, with presence of microcavities. The superelastic wires by GAC and the CuNiTi 27oC and the heat-activated ones by Unitek presented the smallest microcavities and the lowest wire-surface roughness with regard to fracture, while the CuNiTi 35oC wires presented inadequate wire-surface roughness in the fracture region.
Conclusion: CuNiTi 35oC wires did not present better morphologic characteristics in comparison to the other wires with regard to surfaces and fracture region.
Shear bond resistance and enamel surface comparison after the bonding and debonding of ceramic and metallic brackets
Shear bond strength. Tooth enamel. Orthodontic brackets. Scanning electron microscopy.
Objective: To evaluate, in vitro, the shear bond strength presented by three brands of polycrystalline ceramic brackets and one brand of metallic bracket; verify the adhesive remnant index (ARI) after the tests, and analyze, through scanning electron microscopy (SEM) the enamel surface topography after debonding, detecting the release of mineral particles.
Methods: Sixty bovine lower incisors were used. Three ceramic brackets (Allure®, InVu®, and Clarity®) and one metallic bracket (Geneus®) were bonded with Transbond XT®. Kruskal-Wallis’s test (significance level set at 5%) was applied to the results of shear bond and ARI. Mann Whitney’s test was performed to compare the pairs of brackets in relation to their ARI. Brown-Forsythe’s test (significance level set at 5%) was applied to the results of enamel chemical composition. Comparisons between groups were made with Games-Howell’s and the Post-hoc tests.
Results: No statistically significant difference was observed in relation to the shear bond strength loads. Clarity® brackets were the most affected in relation to the surface topography and to the release of mineral particles of enamel (calcium ions).
Conclusion: With regard to the ARI, there was a prevalence of score 4 (40.4%). As for enamel surface topography, the Geneus® bracket was the only one which did not show superficial tissue loss. The InVu® and Clarity® ones showed cohesive fractures in 33.3% and the Allure® in 50%, the latter being the one that presented most fractures during removal.
Comparison of friction produced by two types of orthodontic bracket protectors
Orthodontics. Orthodontic brackets. Friction.
Introduction: Fixed orthodontic appliances have been regarded as a common causative factor of oral lesions. To manage soft tissue discomfort, most orthodontists recommend using a small amount of utility wax over the brackets in order to alleviate trauma. This in vitro study aimed at evaluating friction generated by two types of bracket protectors (customized acetate protector [CAP] and temporary resin protector [TRP]) during the initial stages of orthodontic treatment.
Methods: An experimental model (test unit) was used to assess friction. In order to measure the friction produced in each test, the model was attached to a mechanical testing machine which simulated maxillary canines alignment. Intergroup comparison was carried out by one-way ANOVA with level of significance set at 5%.
Results: The friction presented by the TRP group was statistically higher than that of the control group at 6 mm. It was also higher than in the control and CAP groups in terms of maximum friction.
Conclusion: The customized acetate protector (CAP) demonstrated not to interfere in friction between the wire and the orthodontic bracket slot.
Microscopic evaluation of induced tooth movement after subluxation trauma: an experimental study in rats
Orthodontics. Tooth injuries. Periodontium.
Objective: The objective of this study was to assess the histological alterations that occurred in the periodontal area of rat molars submitted to induced tooth movement (ITM) right after an intentional trauma (subluxation).
Methods: Forty adult male Wistar rats (Rattus norvegicus albinus) were selected. The animals were divided into eight groups (n = 5), according to the combination of variables: Group 1 - control (neither trauma nor ITM); Group 2 - ITM; Groups 3, 4, 5 and 6 - dentoalveolar trauma groups corresponding, respectively, to 1, 3, 8 and 10 days after trauma; Groups 7 and 8 - the animals’ molars were subjected to a 900 cN impact and, one and three days after the trauma event, tooth movement was induced. The rats’ maxillary first molars were mesially moved during seven days with a closed coil (50 cN). After the experimental period of each group, the animals were sacrificed by anesthetic overdose and the right maxillas were removed and processed for histological analysis under light microscopy.
Results: In the animals of group 3, 4, 5 and 6, the histological alterations were not very significant. Consequently, the effect of induced tooth movement right after a subluxation event (groups 7 and 8) was very similar to those described for Group 2.
Conclusion: There was no difference in the quality of periodontal repair when ITM was applied to teeth that had suffered a subluxation trauma.
Comparative photoelastic study of dental and skeletal anchorages in the canine retraction
Orthodontics. Tooth movement. Orthodontic anchorage. Procedures.
Objective: To compare dental and skeletal anchorages in mandibular canine retraction by means of a stress distribution analysis.
Methods: A photoelastic model was produced from second molar to canine, without the first premolar, and mandibular canine retraction was simulated by a rubber band tied to two types of anchorage: dental anchorage, in the first molar attached to adjacent teeth, and skeletal anchorage with a hook simulating the mini-implant. The forces were applied 10 times and observed in a circular polariscope. The stresses located in the mandibular canine were recorded in 7 regions. The Mann-Whitney test was employed to compare the stress in each region and between both anchorage systems. The stresses in the mandibular canine periradicular regions were compared by the Kruskal-Wallis test.
Results: Stresses were similar in the cervical region and the middle third. In the apical third, the stresses associated with skeletal anchorage were higher than the stresses associated with dental anchorage. The results of the Kruskal-Wallis test showed that the highest stresses were identified in the cervical-distal, apical-distal, and apex regions with the use of dental anchorage, and in the apical-distal, apical-mesial, cervical-distal, and apex regions with the use of skeletal anchorage.
Conclusions: The use of skeletal anchorage in canine retraction caused greater stress in the apical third than the use of dental anchorage, which indicates an intrusive component resulting from the direction of the force due to the position of the mini-implant and the bracket hook of the canine.
Dental transposition of canine and lateral incisor and impacted central incisor treatment: A case report
Impacted tooth. Ectopic tooth eruption. Corrective orthodontics.
Introduction: Dental transposition and impaction are disorders related to ectopic eruption or failure in tooth eruption, which can affect child physical, mental and social development and may be difficult to be clinically solved.
Methods: We describe a case of transposition between the upper left canine and lateral incisor associated with impaction of the central incisor on the same side, in a 12-year-old patient. Conservative treatment involving surgical-orthodontic correction of transposed teeth and traction of the central incisor was conducted.
Conclusion: The option of correcting transposition and orthodontic traction by means of the segmented arch technique with devices such as cantilever and TMA rectangular wire loops, although a complex alternative, was proved to be esthetically and functionally effective.
BBO Case Report
Compensatory orthodontic treatment of skeletal Class III malocclusion with anterior crossbite
Crossbite. Tooth extraction. Corrective orthodontics.
Introduction: This case report describes the orthodontic treatment of an adult patient with skeletal Class III malocclusion and anterior crossbite. A short cranial base led to difficulties in establishing a cephalometric diagnosis. The patient’s main complaint comprised esthetics of his smile and difficulties in mastication.
Methods: The patient did not have the maxillary first premolars and refused orthognathic surgery. Therefore, the treatment chosen was orthodontic camouflage and extraction of mandibular first premolars. For maxillary retraction, the vertical dimension was temporarily increased to avoid obstacles to orthodontic movement.
Results: At the end of the treatment, ideal overjet and overbite were achieved.
Conclusion: Examination eight years after orthodontic treatment revealed adequate clinical stability. This case report was submitted to the Brazilian Board of Orthodontics and Facial Orthopedics (BBO) as part of the requirements to become a BBO diplomate.
Life-quality of orthognathic surgery patients: The search for an integral diagnosis
Quality of life. Orthodontics. Orthognathic surgery.